Bosch Diesel Engine Management.pdf

D ystie em 75 l Fu fro S ISBN-3-934584-62-4 Order Number 1 987 722 138 AA/PDT-09.03-En The Bosch Yellow Jackets Edition 2003 Expert Know-How on Automotive Technology se s Ye e l - m Diesel-Engine Management ar Inj Bo s ec sc of t i o h n 2003 Diesel-Engine Management: The Bosch Yellow Jackets An Overview Æ The Program Order Number ISBN Diesel-Engine Management: An Overview Automotive Electrics/Automotive Electronics Motor-Vehicle Batteries and Electrical Systems 1 987 722 143 3-934584-71-3 Automotive Technology Alternators and Starter Motors 1 987 722 128 3-934584-69-1 Automotive Lighting Technology, Windshield and Rear-Window Cleaning 1 987 722 176 3-934584-70-5 Automotive Sensors 1 987 722 131 3-934584-50-0 Automotive Microelectronics 1 987 722 122 3-934584-49-7 Diesel-Engine Management Diesel-Engine Management: An Overview 1 987 722 138 3-934584-62-4 Electronic Diesel Control EDC 1 987 722 135 3-934584-47-0 Diesel Accumulator Fuel-Injection System Common Rail CR 1 987 722 175 3-934584-40-3 Diesel Fuel-Injection Systems • Engine, supercharging and turbocharging, Expert Know-How on Automotive Technology Unit Injector System/Unit Pump System 1 987 722 179 3-934584-41-1 Distributor-Type Diesel Fuel-Injection Pumps 1 987 722 144 3-934584-65-9 fuel injection, emission control Diesel In-Line Fuel-Injection Pumps 1 987 722 137 3-934584-68-3 • Overview of all fuel-injection systems • Fuels Gasoline-Engine Management Emissions-Control Technology for Gasoline Engines 1 987 722 102 3-934584-26-8 Gasoline Fuel-Injection System K-Jetronic 1 987 722 159 3-934584-27-6 Gasoline Fuel-Injection System KE-Jetronic 1 987 722 101 3-934584-28-4 Gasoline Fuel-Injection System L-Jetronic 1 987 722 160 3-934584-29-2 Gasoline Fuel-Injection System Mono-Jetronic 1 987 722 105 3-934584-30-6 Ignition Systems for Gasoline Engines 1 987 722 130 3-934584-63-2 Gasoline-Engine Management: Basics and Components 1 987 722 136 3-934584-48-9 Gasoline-Engine Management: Motronic Systems 1 987 722 139 3-934584-75-6 Safety, Comfort and Convenience Systems Conventional and Electronic Braking Systems 1 987 722 103 3-934584-60-8 ESP Electronic Stability Program 1 987 722 177 3-934584-44-6 ACC Adaptive Cruise Control 1 987 722 134 3-934584-64-0 Compressed-Air Systems for Commercial Vehicles (1): Systems and Schematic Diagrams 1 987 722 165 3-934584-45-4 Compressed-Air Systems for Commercial Vehicles (2): Equipment 1 987 722 166 3-934584-46-2 Safety, Comfort and Convenience Systems 1 987 722 150 3-934584-25-X Audio, Navigation and Telematics in the Vehicle 1 987 722 132 3-934584-53-5 The up-to-date program is available on the Internet at: www.bosch.de/aa/de/fachliteratur/index.htm Robert Bosch GmbH Imprint Published by: Reproduction, duplication and translation of this © Robert Bosch GmbH, 2003 publication, including excerpts therefrom, is only Postfach 1129, to ensue with our prior written consent and with D-73201 Plochingen. particulars of source. Automotive Aftermarket Business Sector, Illustrations, descriptions, schematic diagrams Department of Product Marketing Diagnostics & and the like are for explanatory purposes and Test Equipment (AA/PDT5). illustration of the text only. They cannot be used as the basis for the design, installation, or speci- Editor-in-chief: fication of products. We accept no liability for Horst Bauer, Dipl.-Ing. (FH) the accuracy of the content of this document in respect of applicable statutory regulations. Editorial team: Robert Bosch GmbH is exempt from liability, Jürgen Crepin, Dipl.-Ing. (BA) Subject to alteration and amendment. Karl-Heinz Dietsche, Dipl.-Ing. Printed in Germany. Authors: Imprimé en Allemagne. Stefan Becher, Dr.-Ing. (Application-related adaptation for commercial 1st edition, September 2003. vehicles), English translation of the 1st German edition Henri Bruognolo dated: March 2003 (In-line fuel-injection pumps), (1.0) Michael Durst, Dr.-Ing., Filterwerk Mann+Hummel (Intake air filters), Klaus Grabmaier, Dipl.-Ing. (BA) (Calibration tools), Hermann Grieshaber, Dipl.-Ing. (FH) (Basic principles of the diesel engine, Basic principles of diesel-fuel injection, Application-related adaptation), Thomas Kügler, Dipl.-Ing. (Fuel injectors, Injector sockets), Joachim Lackner, Dipl.-Ing. (Large-scale engines), Werner Pape, Dipl.-Ing. (Actuators), Ulrich Projahn, Dr.-Ing. (UIS/UPS), Johannes K. Schaller, Priv.-Doz. Dr.-Ing. (Emission-control systems), Herbert Schumacher, Dr.-Ing. (Areas of application for diesel engines, Application-related adaptation for cars), Helmut Simon, Dipl.-Ing. (FH) (Distributor injection pumps), Theodor Stipek, Dr. tech. (Discrete cylinder systems for large engines), Jens Wiesner, Dipl.-Ing. (Calibration tools), Thomas Wintrich, Dr.-Ing. (Cylinder-charge control systems) and the editorial team in cooperation with the responsible technical departments of Robert Bosch GmbH. Unless stated otherwise, the above are employees of Robert Bosch GmbH, Stuttgart. Robert Bosch GmbH Diesel-Engine Management: An Overview Robert Bosch GmbH Types 124 Nozzle holders 71 Design. Design 24 Fuel-injection system 93 Method of operation 25 Combustion chambers 96 System diagram for cars 28 Diesel fuels 98 System diagram for commercial 32 Alternative fuels vehicles 34 Cylinder-charge control systems 100 Electronic diesel control EDC 34 Overview 100 Requirements.and closed-loop control 55 Injection characteristics 114 Data processing 60 Injection pressure 61 Injection direction and number 116 Actuators of injection jets 116 Electropneumatic converters 117 Continuous-operation braking 62 Overview of diesel fuel-injection systems systems 117 Fan control function 62 Requirements 118 Start-assist systems 64 Designs 120 Nozzles 70 Overview of in-line fuel-injection 122 Future development of the nozzle pump systems 70 Areas of application.and closed-loop 52 Start of injection and delivery electronic control 54 Injected-fuel quantity 114 Open. Control 126 Exhaust-gas treatment systems 74 Overview of distributor 126 Diesel oxidation-type catalytic fuel-injection pump systems converter 74 Areas of application. Robert Bosch GmbH Contents 4 Areas of use for diesel engines 82 Overview of discrete 4 Suitability criteria cylinder systems 4 Applications 82 Single-plunger fuel-injection 8 Engine characteristic data pumps PF 84 Unit injector system (UIS) and 10 Basic principles of the unit pump system (UPS) diesel engine 88 System diagram of UIS for cars 10 Method of operation 90 System diagram of UIS and UPS 13 Torque and power output for commercial vehicles 14 Engine efficiency 17 Operating statuses 92 Overview of common-rail system 21 Operating conditions 92 Areas of application. Designs 126 Particulate filter 76 Port-controlled systems 127 NOX accumulator-type catalytic 78 Solenoid-valve-controlled systems converter 129 SCR principle 129 Combination systems 130 Index of technical terms 131 Abbreviations . System overview 35 Intake-air filters 101 System structure 38 Swirl flaps 102 Application-related adaptation 38 Turbochargers and superchargers of car engines 49 Exhaust-gas recirculation 106 Application-related adaptation of commercial-vehicle engines 50 Basic principles of diesel 111 Calibration tools fuel-injection 50 Mixture distribution 114 Open. modern diesel engines with high-pressure fuel injection have made substantial progress in respect of driving smoothness and pollutant emission. Furthermore. . the desire to understand more about it has also grown. it provides a comprehensive view of components in diesel- engine management systems. They need no longer fear comparison with any other type of internal-combustion engine. This series of publications also includes other titles that examine in more detail the diesel fuel-injection systems and the electronic diesel-control system EDC outlined in this manual. Robert Bosch GmbH The diesel engine is enjoying a period of increased popularity among motorists. reliability and high-torque output. This manual in the “Automotive Technology” series offers an up-to-date insight into the workings of the diesel engine. This has led to the diesel engine becoming a much more popular choice for cars – including sports cars and luxury-performance cars. Consequently. Its traditional strengths are economy. The continuing development of the diesel engine – and particularly of the direct-injection design – coupled with the rapid advances made in high-pressure fuel-injection systems have consistently brought about further improvements in performance and consumption. It also describes the various Bosch fuel-injection systems. That is why it became established as the engine of choice for commercial vehicles a long time ago. With the increasingly widespread use of the diesel engine. 000 2. Production costs construction and agricultural machinery. Environmental compatibility User-friendliness Diesel engines are produced as inline or Convenience (e. A lot more development work was required. Robert Bosch GmbH 4 Areas of use for diesel engines Suitability criteria. Operational safety heavy goods vehicles. jection system can be optimized specifically 1 Car diesel engine with unit injector system (example) kW 110 90 1 Power P 2 70 3 6 50 30 4 Nm Fig. engine-compartment V-configuration units. are significant for diesel-engine applications (examples): The chief areas of use for diesel engines are Engine power fixed-installation engines. Applications Areas of use for diesel engines No other internal-combustion engine is Suitability criteria as widely used as the diesel engine 1).000 4. This is due primarily to its high degree of effi. for driving 1892. 1 Torque M 320 1 Valve gear 2 Injector 240 æ UMM0603E 3 Piston with gudgeon pin and con rod 5 1.g. ing to the type of application. Applications 1) Fixed-installation engines Named after Rudolf Diesel (1858 to 1913) who first applied for a patent for his “New rational thermal engines” in Fixed-installation engines (e. however. Specific power output cars and light commercial vehicles. They are ideally design) suited to turbocharger or supercharger aspiration as – unlike the gasoline engine – they The relative importance of those character- are not susceptible to knocking (refer to the istics affect engine design and vary accord- chapter “Cylinder-charge control systems”).000 rpm 4 Intercooler Engine speed n 5 Coolant pump 6 Cylinder . The following features and characteristics ciency and resulting fuel economy. Economy of operation railway locomotives and Reliability ships.000 3. the engine and fuel-in- MAN in Augsburg in 1897. power generators) are often run at a fixed before the first functional diesel engine was produced at speed.g. Consequently. the ing emission characteristics will continue to diesel engine has forced its way into the be a major challenge for diesel-engine devel- executive and luxury-car markets. Great progress has been made in not by the engine but by the power-trans- these areas by refinements in engine design mission system. used in large saloons to 3-cylinder 800-cc injection systems are still used.500 rpm 2 Injector Engine speed n 3 Fuel rail 4 High-pressure pump .000 1.500 2. posed and continually increasing power de- stantial improvements in the power output mands require fuel-injection systems with and torque characteristics of diesel engines extremely high injection pressures. models for small subcompacts. Cars use fast-running diesel engines capable nor adjusts the quantity of fuel injected de. now almost exclusively fitted with turbochargers. of speeds up to 5. 2 400 1 Alternator 1. further innovations can be expected in the area of exhaust-gas treatment in years to come. ble gasoline engines. offer considerably Cars and light commercial vehicles better torque characteristics than compara- Car engines (Figure 1) in particular are ex. The ever more stringent emission limits im- Those advances have paved the way for sub. The range of pendent on engine load. direct-injection (DI) designs as they offer However. the engine-control system may fuel consumption reductions of 15 to 20% have to be modified to suit the different in comparison with indirect-injection en- conditions. opers in the future.500 rpm. and the development of new fuel-injection with Electronic Diesel Control (EDC). The maximum torque pected to produce high torque and run available to a vehicle is generally determined smoothly. Car and commercial-vehicle engines can In Europe. And as a result. 2 Commercial-vehicle diesel engine with common-rail fuel-injection system (example) kW 2 160 1 120 Power P 3 80 40 0 Nm 700 Torque M 4 600 500 æ UMM0604E Fig. Improv- since the early 1990s. Consequently. gines. Robert Bosch GmbH Areas of use for diesel engines Applications 5 for operation at that speed. all new diesel engines are now also be used as fixed-installation engines. mechanically governed fuel. Such engines. An engine gover. For this type of sizes extends from 10-cylinder 5-liter units application.000 2. There are out-and-out high- for car engines. Maximizing power uti. In why diesel engines for this type of applica. the ruggedness and simplicity of the air- gines that run at speeds of up to 3. reliability and Ships ease of maintenance. For large commercial vehicles too. continuous-duty considerations in mind.500 rpm and have up to 3 Marine diesel engine with single-plunger fuel-injection pumps (example) kW v 1 1. They are generally medium-fast en. power outputs can range from around or speedboats.1. Railway locomotives That means exacting demands on the fuel. For this type of performance engines for fast naval vessels use. for example. for example. Construction and agricultural machinery is they range from the equivalent of a large the traditional domain of the diesel engine. contrast with all other areas of application. These tend to 3 kW to the equivalent of HGV engines.000 rpm curve Engine speed n v Full-load limitation zone . like heavy-duty marine injection system used and a need to develop diesel engines.200 b Power P P 800 Fig. places particular emphasis not only on economy but also on durability. tion are exclusively direct-injection (DI) where water-cooled engines are the norm. Robert Bosch GmbH 6 Areas of use for diesel engines Applications Heavy goods vehicles Many engines used in construction-industry The prime requirement for engines for heavy and agricultural machines still have mechan- goods vehicles (Figure 2) is economy.600 a 1. cooled engine remain important factors in the building and farming industries. truck engine to that of a medium-sized The design of engines for such applications marine engine. The demands placed on marine engines vary lization and minimizing noise output are less considerably according to the particular type important considerations than they would be of application. That is ically governed fuel-injection systems... Locomotive engines. 3 1 Turbocharger 2 Flywheel 2 400 a Engine power æ UMM0605E output 0 b Running-resistance 400 600 800 1. the emission limits are continually being lowered. they often have to cope with Construction and agricultural machinery poorer quality diesel fuel. are designed primarily with new emission-control systems.500 rpm. be 4-stroke medium-fast engines that run at speeds of 400. In addition. designs. In terms of size. The first volume-production car to be fit- The biggest obstacle to the development of ted with a diesel engine was the Mercedes- a fast-revving diesel engine was the fuel sup.580 cc and produced 27 horsepower (about 20 kW). It developed 20 horsepower at 175 rpm. . plete. The air-blast method used at that Diesel’s vision had at last become reality. After many years of hard work. In addition. the not be significantly reduced. engine speeds. 50 hp). Since that time it were the demands for a smaller. the more insistent speeds in diesel engines.. world’s first diesel engine was produced in 1897. Robert Bosch GmbH Areas of use for diesel engines History of the diesel engine 7 History of the diesel engine In 1892 Rudolf Diesel (1858 to 1913) em. By the beginning of 1923. Rudolf ply system. The engine had a capacity of 2. the compressor required which the fuel would be ignited by compres. there were problems in achieving higher Stuttgart factory in 1927. was not barked on research work at MAN in Augsburg capable of adaptation to higher engine based on his idea of a totally new engine in speeds. tion. a dozen different designs for fuel-injection self was cheaper to begin with) and could be pumps had been produced. faster-running has conquered ever wider areas of applica- version. this engine had a number of advan. The more widespread the Those Bosch fuel-injection pumps were diesel engine became. How. tion chamber by compressed air. The first series-production units left the ever. By the summer of 1925. was very large so that size and weight could sion. Diesel’s invention rapidly established itself in the design of the injection pump was com- the marine and fixed-installation sectors. In the latter part of 1922. The first tests of dimensioned for much higher power outputs.580 cc. and the more widely the breakthrough in achieving higher running known its advantages were. time. 1 This fuel-injection pump æ SMK1752Y was tested out in a Stoewer motor car in 1927. around tages: It used substantially less fuel (which it. where fuel was sprayed into the combus- One of the first series-production Bosch Type PE. Robert Bosch Compared with the conventional power decided to direct its attention to the develop- units of the time (steam engines and gasoline ment of a fuel-injection system for diesel engines). Benz 260D in 1936 (2. engines.A fuel-injection pumps Fig. the system fitted to the engine started in the middle of that year. .11:1 12..500.500.. Such slow-running engines tures or for military use).000. Table 1 shows the most important compari- Smaller vessels often use engines originally son data for various types of diesel and intended for large commercial vehicles.....9 20. The compression ratio of such engines can be as much as 13:1....190 25 Marine engines (2-stroke) 50...250 Indirect Injection 4) Turbocharged car engines 5..18 1:9.. At the same to the different service profile....500.30 1:6....3....190 Mspec [Nm].. capable of running on a variety of different ciency of up to 55 %...600...23 6.105 1:2...200 15..205 the specific torque.. an economical propulsion unit The average pressure in petrol engines with low development costs can be pro..24:1 7..........4.. emissions and performance characteristics..15 85.. In gasoline engine..20:1 8..26 1:16. and agricultural machine engines 1..20 15.......18:1 7. engines with i/clr 5) 1...1... the specific fuel consumption is up to 25 % lower.45 1:4...600 16. with direct fuel injection is around 10 % duced..000 20. diesel engines (< 300 rpm) achieve effective levels of effi. This requires pretreatment meeting the current demands in respect of of the fuel on board..... Only then is its viscosity reduced to a level at which it can be filtered and Engine characteristic data pumped. pe.4.240 Table 1 DI 4) conventionally aspirated car engines 3.. veh.....9:1 8.60 1:4.7..000 12.220 1) The average pres.....2 225. however.5.5...4 260..1. by Construct. aspirated comm...3 320...21:1 7..3 230.500.28 1:10..3..........7...250 Direct Injection 5) Comm. time...1 280..2 210.8:1 14.26 10.18:1 15..8 1:32. veh.20:1 7.18:1 15....240 IDI 3) turbocharged car engines 3. engines 2.200 19.10 10...500 10.400 16.. Once again.22 30. it has to be heated to temperatures as high as 160 °C.24:1 9.250 6.500 20....3......12 30.25 1:8.1 380.23 1:10. At present they are of virtually no significance whatsoever within Large-scale engines are generally run on the overall picture..210 used to calculate DI 4) turbocharged comm. veh.500 13...9 20. spec [kW/l] Rated speed Fuel-injection system Specific fuel nrated [rpm] be [g/kWh] pe [bar] output ratio ratio ε Diesel engines IDI 3) conventionally aspirated car engines 3...... At the other end of Multi-fuel engines the scale there are 2-stroke heavy-duty en. comm.. can be DI 4) convent...35 1:5..35 1:5.15 50. 1 Comparison of diesel and gasoline engines Mean pressure 1) Power-to-weight consumption 2) Specific power mspec [kW/kg] Compression pe.000.. DI 4) turbocharged car engines with i/clr 5) 3...2.. that way.500. DI 4) turboch.000 7. Robert Bosch GmbH 8 Areas of use for diesel engines Applications..10 20.. veh..3 240.190 means of the Locomotive engines 750..1 350..23 20.2 290... engines 2.000. engines 2. have been developed.18 3..15:1 17... For specialized applications (such as opera- gines designed for maximum economy in tion in regions with undeveloped infrastruc- continuous duty.5 210...... Engine characteristic data 24 cylinders (Figure 3)...000...75 1:2...16 180. as they are incapable of cheap heavy oil.800. the engine higher than for the engines listed in the table management system has to be adapted with inlet-manifold injection..... which represent the fuels including diesel.270 Intercooler .200 following equation: Marine engines (4-stroke) 400.500 16...000 7.35 1:5.160 Mspec = π · pe Gasoline engines 2) Best consumption 3) Conventionally aspirated car engines 4..... gasoline and others highest attainable with piston engines.25 25.17:1 18.600 16.13 210.....9:1 11..195 sure. Depending on quality.4.3 380.... diesels had a number of other fea.400 hp) take-off power. Based on the experience gained from that engine. It was that fuel-injection system which was a major factor in the breakthrough of the Jumo 205. In those days. The injection pressure was in excess of 500 bar. a take-off power output of 645 kW (880 hp).g. Around 900 units of this reliable engine were built. It had a take-off power output of up to 645 kW (880 hp). with the new engine could reach altitudes of tures in their favor such as a lower fire risk and up to 14. fitted in numerous planes. Munich) . of diesel aircraft engines was the experimental tion engine would provide good performance 24-cylinder opposed-piston Jumo 224 pro- at high altitudes. ignition system was subject to atmospheric This “square configuration” engine had its pressure. involved controlling the fuel/air mixture effectively and handling the higher mechanical and A whole series of diesel aircraft engines were thermal stresses. The technical high point in the development neers also hoped that the compression-igni. nomical consumption and the lower price of Thanks to its turbocharger aspiration. The fuel injection system for the Jumo 205 con- sisted of two pumps and two injectors for each cylinder. (Source: Deutsches Museum. Engi. diesel aircraft engine e. However. Following its introduction in 1933 it was ignition engines with fuel injection. Robert Bosch GmbH Areas of use for diesel engines Diesel aircraft engines 9 Diesel aircraft engines of the 1920s and 30s In the 1920s and 1930s numerous two and The Jumo 205 was followed in 1939 by the four-stroke diesel engines were developed for Jumo 207 high-altitude engine which also had use as aircraft engines. Its strengths primarily lay in its suitability for Junkers Jumo 205 two-stroke opposed-piston long-distance flights at constant speeds. for transatlantic postal services. spark plugs and magneto. The main problems associated with cylinders arranged in a cross formation driving the development of a diesel aircraft engine four separate crankshafts. Apart from their eco. progress made with high-performance spark- tion). simpler maintenance due to the absence of carburetor. developed by other manufacturers as well. development work æ SMM0606Y was also started on direct fuel-injection for spark-ignition aircraft engines in the 1930s. spark-ignition duced in the early 1940s which developed as engines were liable to misfire because the much as 3.000 metres. none of them progressed beyond The most successful production aircraft diesel the experimental stage.330 kW (4. aircraft diesel fuel. In later years interest engine was the Jumo 205 6-cylinder two-stroke in diesel aircraft engines waned because of opposed-piston heavy-oil engine (see illustra. the piston (Figure 1. its low-emission exhaust and cylinder (5) performs up-and-down move- quieter running characteristics assisted. The types injected into the cylinder. 1 1 7 11 Camshaft 12 Valves 2 13 Piston 8 14 Fuel-injection system 3 15 Cylinder 43 6 9 16 Exhaust-gas recirculation 10 11 5 17 Intake manifold 15 18 Turbocharger 19 Exhaust pipe 14 10 Cooling system 12 æ SMM0608Y 11 Connecting rod 13 12 Lubrication system 13 Cylinder block 14 Crankshaft 15 Flywheel . ders. to the end of the crankshaft helps to maintain lutant emissions and combustion noise. Driven by the combustion of the air/fuel slow-running types). This method of operation is why it example. The associated low fuel mixture. converts Diesel engines are particularly suited to aspi. Robert Bosch GmbH 10 Basic principles of the diesel engine Method of operation Basic principles of the diesel engine The diesel engine is a compression-ignition take manifold (exhaust-gas recirculation). The speed of rotation of the crank- exhaust gas is fed back into the engine’s in. engine in which the fuel and air are mixed An even greater reduction of NOx emissions inside the engine. give the diesel engine its present significance. The diesel engine used in motor vehicles are generally four- thus uses heat to release the chemical en. continuous crankshaft rotation and reduce unevenness of rotation caused by the periodic In order to reduce NOx emissions on cars nature of fuel combustion in the individual and commercial vehicles. shaft is also referred to as engine speed. for ments. can be achieved by cooling the recirculated bustion is highly compressed inside the exhaust gas. The connecting rod. a proportion of the cylinders. Item 3) in each consumption. Method of operation The diesel engine is the internal-combustion engine that offers the greatest overall effi. ergy contained within the diesel fuel and convert it into mechanical force. This not only improves the engine’s crankshaft (14). stroke designs. 1 Four-cylinder diesel engine without auxiliary units (schematic) Fig. it also reduces pol. into rotational movement on the part of the charger. or conrod (11). This generates high temperatures which are sufficient for the Diesel engines may operate either as two- diesel fuel to spontaneously ignite when it is stroke or four-stroke engines. the linear reciprocating action of the piston ration by means of a turbocharger or super. A flywheel (15) connected power yield and efficiency. The air required for com. A diesel engine contains one or more cylin- ciency (more than 50% in the case of large. combustion chamber. by pre-injection have combined to was named the “reciprocating-piston engine”. The into the cylinder without restriction by a pressure forces the piston downwards. pressurized gases flow out of the engines to 24 : 1 in car engines). the cylinder capacity is at its smallest (compression volume. 2 a b c d a Induction stroke 1 10 b Compression stroke 2 c Ignition stroke d Exhaust stroke 3 TDC Vc Vh 4 11 Inlet-valve camshaft s d 12 Fuel injector 5 13 Inlet valve BDC 14 Exhaust valve 6 15 Combustion 7 chamber æ UMM0013-3Y 8 16 Piston 9 α 17 Cylinder wall 18 Connecting rod M 19 Crankshaft 10 Exhaust-valve camshaft Four-stroke cycle 3. The inlet and exhaust valves are now closed. As a result. . Each inlet and ex. ratio (this can vary from 6 : 1 in large-scale The hot. When the piston reaches bot.000 bar in modern engines) into the hot. and the four-stroke operating cycle starts compressed air. the cylinder capac. the exhaust valve (4) opens. The ity is at its greatest (Vh+Vc). When the piston reaches top again with the induction stroke. the pressure in the cylinder rises further as well. the injects fuel at high pressure (as much as crankshaft has completed two revolutions 2. diesel fuel spontaneously ignites and burns Vc Compression haust port may have one or two valves. cylinder. chemical energy released by combustion is tom dead center (BDC). the fuel-injection system On completion of the exhaust stroke. In the pro. The piston moves upwards and compresses 4. of rotation inlet and exhaust valves control the intake of d Bore air and expulsion of burned gases after com. Vc). the air heats up to temperatures as high it forces the remaining exhaust gases out. thus converted into kinetic energy. After the ignition lag (a few degrees of α Crankshaft angle crankshaft rotation) has elapsed. At the same time tion is essentially determined by the mass of the inlet valve (3) is opened and air is drawn fuel injected (quality-based control). BDC Bottom dead The amount of energy released by combus. tion stroke (working cycle) begins. Fractionally before the piston reaches bot- gree determined by the engine’s compression tom dead center. cess. When the compression stroke is almost complete. Exhaust stroke (d) the air trapped inside the cylinder to the de. The M Turning force bustion. They open and close the cylinder’s finely atomized and easily combustible s Piston stroke inlet and exhaust ports. the Vh Swept volume 1. due to the heat of the compressed air in the volume combustion chamber (5). The throttle valve. as 900 °C. crankshaft drive translates the piston’s kinetic energy into a turning force (torque) 2. Induction stroke (a) cylinder charge heats up even more and the TDC Top dead center Starting from top dead center (TDC). Robert Bosch GmbH Basic principles of the diesel engine Method of operation 11 2 Operating cycle of a four-stroke diesel engine Fig. the igni. dead center. center piston (6) moves downwards increasing the capacity of the cylinder. Compression stroke (b) available at the crankshaft. Ignition stroke (c) On a four-stroke diesel engine (Figure 2). As the piston moves upwards again. the engine’s cold-starting characteristics tion stroke. °C 900 Valve timing involves synchronizing the Temperature in cylinder opening and closing of the valves with the rotation of the crankshaft (Figure 4).50 bar (conven- E xh IO Inlet opens uc IC Inlet closes tionally aspirated engine) or 70. and its tions of the crankshaft. The compression ratio. Therefore. the speed compression volume.13 : 1). For Ignition temperature æ SMM0609E of diesel fuel that reason. valve timing is specified in Fig. a rocker-arm mechanism transmits the action of the cams to the valves. . This TDC Top dead center æ UMM0610E IC generates temperatures ranging from 700 to 20 BDC BDC Bottom dead … ° 60° 60 900 °C (Figure 3). On a four-stroke engine. is generally between 16:1 and 24:1 in engines for cars and 4 Valve-timing diagram for a four-stroke diesel engine commercial vehicles. The transmission ratio ε= Vc between the crankshaft and the camshaft is thus 2 : 1.. thus: of rotation of the camshaft is only half that Vh + Vc of the crankshaft. On engines with a single camshaft. Robert Bosch GmbH 12 Basic principles of the diesel engine Method of operation Valve timing 3 Temperature rise during compression The cams on the inlet and exhaust camshafts open and close the inlet and exhaust valves respectively. Due to the suscepti- 25° 0… bility of gasoline to knocking... The ignition temperature center (70°) 40 … of the most easily combustible components Valve overlap of diesel fuel is around 250 °C. cylinders. tion SOC Start of combustion The air inside a diesel engine is com- tion pressed to a pressure of 30.. Vh. results from its swept volume. 8° It is therefore higher than in gasoline en- 0… 2…15° 5…30° gines (ε = 7 : 1. and out” the remaining exhaust and cool the the pollutant emissions. the inlet and exhaust valves are the torque generated open simultaneously for a certain period its fuel consumption of time. 40 TDC Top dead center TDC Piston stroke BDC BDC Bottom dead The crankshaft drives the camshaft by center means of a toothed belt or a chain (the timing belt or timing chain) or sometimes by Compression a series of gears. 3 degrees of crankshaft rotation. ε. of a cylinder a complete operating cycle takes two revolu.150 bar au nd t I s IP Injection point EO (turbocharged/supercharged engine). depending on the engine design and the fuel-injection method. This “valve overlap” helps to “flush how noisy it is. 4 SOC C combustion-chamber temperatures would on om EO Exhaust opens IO ssi EA EC cause the air/fuel mixture to spontaneously bus EC Exhaust closes Compre combust in an uncontrolled manner. The compression ratio of an engine has a decisive effect on the following: At the changeover from exhaust to induc. The compression ratio. Vc. higher com- IP TDC pression ratios and the resulting higher Fig.. ε.. with engine speed until it reaches its maxi- The output torque.000 2. By comparison. gasoline engines achieve levels of 7. 0 1. that the engine can deliver is determined by its design (cubic capacity. As the engine speed in. Engine power output increases shaft.000 rpm) because at those speeds fuel 100 1 consumption is at its most economical and nrated 1 1968 engine æ NMM0556-1E 0 2 1998 engine the engine’s response characteristics are per. is reached (Figure 1). until maximum torque. Mod- The mean pressure can reach levels of ern diesel engines for cars have rated speeds 8. Prated Torque increases in relation to engine 25 1 speed. gine’s rated speed. The torque output is adjusted Prated to the requirements of the driving situation 75 2 essentially by altering the fuel and air mass Power P 50 and the mixing ratio.000 3.. 2 Fig.000 4.22 bar in small turbocharged diesel of between 3. 0 creases beyond that point. n. The force with which the ex- panding air/fuel mixture forces the piston Figure 1a shows a comparison between the downwards is thus translated into a turning power curves of diesel engines made in 1968 force or torque by the leverage of the crank.. 2.11 bar..000 rpm ceived as positive (good “pulling power”).500 and 5. VH is the cubic capacity of the engine and Because of their low maximum engine π ≈ 3. Robert Bosch GmbH Basic principles of the diesel engine Torque and power output 13 Torque and power output Power output The power. M. Engine speed n Mmax Maximum torque Prated Rated power nrated Rated speed . gearbox design).000 rpm. the torque begins b Nm • to fall again (maximum permissible engine Mmax 300 load. diesel engines have a lower specific power output than gasoline engines. n. The re- of the piston into a rotational movement on lationship is expressed by the equation: the part of the crankshaft because its point of action is offset from the crankshaft’s cen. and in 1998. 1 Torque and power curves for two diesel car engines with a capacity of approx. of the engine is mum level. speeds.. method of aspira.). nrated. pe (mean piston or operating pressure).2l (example) The maximum achievable torque.14. It is expressed by the equation: The power-output and torque characteristics of the internal-combustion engine require pe · VH M= the use of a gearbox that can adapt engine 4π output to the varying requirements of dif- where ferent driving situations. etc. Mmax. or rated power Prated at the en- therefore dependent on the mean pressure. Mmax b Torque curve der 2. M. and engine speed. desired performance. engines for cars. a kW tion. gener- Torque ated by the engine increases in relation to The conrod converts the linear movement torque. P=2·π·n·M ter of rotation. P (work per unit of time). Mmax. 1 Engine design efforts are aimed at generating Torque M 200 a Power curve maximum torque at low engine speeds (un. e. sion at constant entropy. This takes place at a con- 2–3 Isochoric heat stant gas volume (completely and at infinite p propagation qBp speed). that it performs. For as- W center sisted-aspiration engines. The heat therefore the work theoretically achievable propagation (qBV) that takes place as a result by the diesel engine. W. Seiliger process The Seiliger process (Figure 1) describes the Isochoric heat propagation (2–3) thermodynamic comparison process and The air/fuel mixture starts to burn. theoretically achievable Pressure-volume diagram (p-V diagram) in the course of an operating cycle. During isentropic compression (compres- resented by a pressure-volume work dia. 3‘–4 Isentropic 3 3' expansion Real process Cylinder pressure 4–1 Isochoric heat qBV The real process can also be represented by dissipation a p-V diagram (indicator diagram. They are rep. sign is to achieve a real process that approxi. The fol- The changes in gas pressure and consequent lowing individual stages make up the process: variations in volume that take place inside a diesel engine are responsible for the theoret. The initial situation is thus restored 3–3’ Isobaric heat propagation and a new operating cycle begins. W Theoretical work . or p-V diagram. mates the Seiliger process as closely as possible. does so at a constant gas volume (isochoric). the gas-exchange 4 qA area (WG) has to be added to that since the qA Quantity of heat 1 compressed air delivered by the turbo- dissipated during charger/supercharger also helps to press the gas exchange piston downwards on the induction stroke. Gas pressure also increases. Robert Bosch GmbH 14 Basic principles of the diesel engine Engine efficiency Engine efficiency The enclosed area in the p-V diagram describes the work. without transfer gram. of heat) pressure in the cylinder increases while the volume of the gas decreases. the remaining compression heat is removed (qA). Fig. W. bottom dead center. 1 Isochoric heat dissipation (4–1) 1–2 Isentropic 1 Seiliger process for diesel engines During the gas-exchange phase. No further heat transfer takes place. The aim of engine de. i. dissipation no flow-related losses as the theoretical Isentropic expansion (3‘–4) process does not take account of the The piston continues to move downwards to processes involved in charge cycles. Isentropic compression (1–2) ical work. The ideal process is based on the follow. Isobaric heat propagation (3–3’) ing simplifications: Further heat propagation (qBp) takes place ideal gas quality when the piston moves downwards (the gas constant specific heat volume increases). The indicated (generated) work is the upper TDC Top dead center 2 BDCBottom dead enclosed area on the diagram (WM). The gas volume increases. qBp Combustion heat at TDC BDC V æ SMM0611E The process is also frequently represented constant pressure Cylinder volume qBV Combustion heat by a graph of cylinder pressure versus crank- at constant volume shaft rotation (Figure 3). Figure 2). the pressure remains infinite speed of heat input and constant (isobaric). 2 EO Exhaust opens EC Exhaust closes SOC Start of combustion IO Inlet opens TDC BDC IC Inlet closes TDC Top dead center pZ BDC Bottom dead center Cylinder pressure SOC pU Ambient pressure pL Charge-air pres- WM sure pZ Maximum cylinder pressure EO Vc Compression IC EC volume pL WG Vh Swept volume pU IO WM Useful work æ SMM0612E Vc Vh WG Work during gas exchange Swept volume (turbocharger/ supercharger) 3 Pressure vs. Robert Bosch GmbH Basic principles of the diesel engine Engine efficiency 15 2 Real process in a turbocharged/supercharged diesel engine represented by p-V indicator diagram (recorded using a pressure sensor) Fig. 3 EO Exhaust opens EC Exhaust closes SOC Start of combustion IO Inlet opens IC Inlet closes pU TDC Top dead center BDC Bottom dead IO IC IO center æ SMM0613E EC EO EC pU Ambient pressure pL Charging pressure pZ Maximum cylinder pressure . crankshaft rotation curve (p-α diagram) for a turbocharged/supercharged diesel engine Crankshaft angle of rotation 0 180° 360° 540° 720° TDC BDC TDC BDC TDC pZ Cylinder pressure SOC Fig. This efficiency figure takes ac- WB count of the heat and flow-related losses where We is the work effectively available of the real gas-exchange phase. ence to the indicated process. It represents the theoretical work Mechanical efficiency. of the diesel work process. 5 %. Frictional and As previously outlined. The best 30…45% and gasoline engine efficiency levels are The higher overall efficiency of the diesel achieved by large-scale ηm=75…90% slow-running engines. this must they are designed. Useful work Comparison of diesel engine cantly as well. real gas quality heat losses That overall efficiency figure is the com. 20 % dissipation oil pump approx. their levels of efficiency differ signifi. the parameters of power-transmission losses increase with this “ideal process” are: engine speed.5 MJ/kg for tion including ancillary systems with refer- diesel engines. at the flywheel and WB is the energy content Its parameters are: of the fuel consumed. also be included. Diesel engines vary 4 Efficiency losses of motor-vehicle diesel engine greatly in size and at full power application for which If the engine has a supercharger. 10 % Fig. . and dissipation. It therefore describes the real engine. 4 fuel-injection pump approx. 10 % no flow-related losses coolant pump approx. ηe. ηg engine is represented by the equation ηg describes the real high-pressure work process in relation to the theoretical process We ηe = (Figure 2). the frictional ideal gas quality losses are made up as follows: constant specific heat pistons and piston rings approx. ηth influence on thermal efficiency. ratio ε and the ηth=50…60% greater excess air (made possible by het- excess-air factor λ) æ SMM0614E erogeneous internal air/fuel mixing). and ηg Efficiency of the high-pressure work absence of throttle flap – and conse- process quently no throttle-related losses in the ηm Mechanical efficiency part-load range. finite rate of heat propagation bined result of a series of individual effi. Therefore. Robert Bosch GmbH 16 Basic principles of the diesel engine Engine efficiency Efficiencies Efficiency of high-pressure The overall efficiency. ηm in relation to the energy content of the fuel ηm defines the mechanical losses due to fric- consumed and is around 42. At rated speed. and ciency ratings (Figure 4) which all constitute variable specific heat energy losses: ηe = ηth · ηg · ηm All air/fuel mixture parameters have an effect on combustion and therefore a decisive Theoretical efficiency. ηg=75…80% engine compared with the conventional gasoline engine is essentially due to three ηth Theoretical efficiency factors: (alters in relation to higher compression ratio (giving a larger the compression area on the p-V indicator diagram). 5 % valve-gear approx. 50 % infinite speed of heat propagation and bearings approx. ηth is the theoretical efficiency of the Seiliger process. The minimum ignition In addition. ignition and running during the compression stroke. the ical factors as outlined below. ultimate temperature (Figure 1). Because the precipitation of paraffin crystals. Robert Bosch GmbH Basic principles of the diesel engine Operating statuses 17 Operating statuses maximum compression temperature is reached a few degrees before TDC Starting (thermodynamic loss angle. A filter heater or direct fuel heater (Figure 3 tween the piston and the cylinder wall overleaf) can prevent fuel problems which and the fact that when the engine is first generally occur at low temperatures due to started. Starting an engine involves the following When the engine is cold. The oil of the heat loss during compression. (combustion start). The hot. a sufficient degree of certainty at low engine Furthermore. rect-injection (IDI) engines. the internal friction of the temperature required for diesel fuel is engine is higher at low temperatures than approx. parameters which tend to oppose that aim: The lower the engine speed. 2 ta Outside temperature tZ Ignition temperature æ UMK0794-1E æ UMK0791-1E of diesel fuel 0 100 200 300 rpm 100° 80° 60° 40° 20° αT Thermodynamic loss angle Engine speed n Crankshaft degrees before TDC n ≈ 200 rpm . The reasons for this phenomenon are the leakage Fuel modification losses through the piston ring gaps be. Figure 2). an oil film is not present. that heat loss compressed air produced by the compres. 250 °C. the speed of the starter mo- speeds and in cold weather conditions with a tor is slower when it is cold because the cold engine. heat loss occurs stages: cranking. at normal operating temperature because That temperature must be achievable with of the higher viscosity of the engine oil. On indi- up to self-sustained operation. There are a number of physical battery voltage drops at low temperatures. the lower is There are a number of measures that can be the ultimate pressure at the end of the employed in order to counteract those phys- compression stroke and accordingly. the industry also supplies fuels suitable for use 1 Compression pressure and ultimate temperature 2 Compression temperature when starting from cold relative to engine speed relative to angle of crankshaft rotation bar °C Compression pressure pc αt pc 400 Compression temperature 300 tZ C 200 ta 0° C Final compression tc ta – 20° C temperature tc 100 Fig. is particularly high due to the larger sur- sion stroke has to ignite the injected fuel face area of the combustion chamber. must be achieved as precisely as possible fore facilitate reliable combustion of the within tight tolerance limits. On A further method involves advancing the indirect-injection (IDI) engines. Both the above methods assist fuel perature. these “winter-grade fuels” (refer to the section “Diesel fuels”). phase) and the piston is not fully accelerated. ignition occurs plugs also enables even longer post-glow pe. The addition of paraf. This reduces not only harmful pollu. The optimum start of injection vaporization and air/fuel mixing and there. 3 Diesel fuel heater 4 Temperature progression of two glow plugs in still air °C 1 1 1. during the downward stroke (expansion riods. since at require only a few seconds to preheat to the that point the temperature of the air charge required temperature and thus enable quick is too low. The lower post-glow temperature of the latest generation of glow If the fuel is injected too late. assisted to compensate for condensation and leakage starting is achieved partially by pre-heating losses and to increase the engine torque in the intake air (commercial vehicles) or by the running-up phase. tant emissions but also noise levels during fin or gasoline is no longer necessary with the engine’s warm-up period. Injection adaptation Another means of assisted starting is the in- Start-assist systems jection of an excess amount of fuel for starting On direct-injection (DI) engines. 3 950 1 Fuel tank 2 Fuel heater 3 Fuel filter 4 Fuel-injection pump 850 3 4 Fig. air/fuel mixture. at the maximum final compression tem- chamber. Robert Bosch GmbH 18 Basic principles of the diesel engine Operating statuses in cold temperatures. assisted start of injection to offset ignition lag and to starting is achieved exclusively by means of ensure reliable ignition at top dead center. starting (Figure 4).050 2 2 Temperature t Fig. glow plugs in the prechamber or swirl i. it con- denses on the cold cylinder walls. If the fuel is injected too soon. the use of sheathed-element glow plugs (cars) (refer to the section “Actuators”).e. 4 750 Filament material: 1 Nickel (conventional æ UMS0665-1E æ UMK0792-1Y glow plug type 650 S-RSK) 0 10 20 30 40 50 s 2 CoFe alloy (2nd- Time t generation glow plug type GSK2) . Only a The most technically advanced glow plugs small proportion of it vaporizes. including breakaway speed are possible. Start of injection is controlled very possible (lower) full-load torque with the precisely to coincide with that point. Pre-injection of approx. within a small range of piston travel near sure) the engine develops the maximum TDC. chamber is relatively cool (even when the gine is not generating any output torque. All engine speeds up to and nated on diesels with pre-injection. “Diesel knock” that was internal friction. Under non steady-state conditions combustion temperature is reached only (limited by turbocharger/supercharger pres. This (breakaway speed) is then called the upper is particularly true of engines with precham- idle speed. sible torque output under steady-state con. At low loads and with pre-injection. The greater the increase possible torque. quantity of air available. The accelerator pedal may be ularly when cold – has virtually been elimi- in any position. the accelerator pedal is fully de. The engine gener- combustion chamber is achieved by opti. start of injection and injected fuel quantity. This may extend to full mum fuel atomization and delivery (see the load. chapter “Basic principles of diesel fuel injection”). the governor holds and efficiency of air/fuel mixing inside the the engine at idle speed. the combustion accelerator pedal is not depressed. in pressure. 1 mm3 of fuel virtually cancels out the ignition lag at . The en. the quantity of fuel in the Part load combustion chamber determines the sudden Part load covers the range between no load increase in pressure in the cylinder. ber or swirl chambers because the larger surface area means that heat loss is greater. the energy input and therefore the tempera- Some sources refer to the entire no-load ture rise is necessarily smaller. the more clearly perceptible is the noise. The comparison with full load. amount of fuel may be injected since. In running at the lowest no-load speed. The combus- range as idle. ates torque output. In this situation. Full load At full load. only pressed or the governor acts independently a few mm3 are delivered in each injection within the range up to fuel shutoff. Robert Bosch GmbH Basic principles of the diesel engine Operating statuses 19 The injection system has to ensure that the Part load at idle speed correct fuel-droplet size for optimum speed In this particular case. at the point of ignition. The cycle. only a small possible. the highest ditions. the Idle final compression temperature is lower at The engine is said to be idling when it is lower engine speeds and at lower loads. particularly high maximum possible fuel volume is injected demands are placed on the accuracy of the and the engine generates its maximum pos. As explained in the “Starting” section. All engines speeds from idle speed to nominal speed are During the ignition-lag period. As during the starting phase. The engine is generating an of combustion noise is directly related to this output between zero and the maximum pressure increase. Lower part-load range This is the operating range in which the No load diesel engine’s fuel consumption is particu- No load refers to all engine operating statuses larly economical in comparison with the in which the engine overcomes only its own gasoline engine. engine is at operating temperature) because It overcomes only internal friction. The upper no-load range tion chamber heats up relatively slowly. The level and full load. It does not produce any a problem on earlier diesel engines – partic- torque output. Transition between operating statuses tially reduces combustion noise (see the The response characteristics of an engine chapter “Basic principles of diesel fuel can be defined by means of characteristic injection”). The engine speed is con. data diagrams or maps.g.g. the required torque. the engine speed or the accelerator- Overrun pedal position change. the power demand and the en- Non-steady-state operation gine’s power output are equal. the engine’s operat- The engine is said to be overrunning when it ing status changes (e. The engine The engine’s torque output is not equal to speed has increased from nA to nD. for example. The map in Figure 5 shows an example of how the engine speed changes when the ac- Steady-state operation celerator-pedal position changes from 40% The engine’s torque output is equal to the to 70% depressed. the new part-load point D is stant. reached via the full-load curve (B–C). If. Starting from point A required torque. when descending an incline). the load. At that point. the drivetrain (e. its speed or torque is driven by an external force acting through output). Robert Bosch GmbH 20 Basic principles of the diesel engine Operating statuses the main injection point and thus substan. The engine speed is not constant. 5 Injected-fuel quantity relative to engine speed and accelerator-pedal position (example) mm3 Start quantity Power requirement Stroke Full-load curve Injected fuel quantity QH C B D 70% A 50% 40% Speed- regulation breakaway 10% æ SMK1876E nA nD rpm Engine speed n . on the map. for commercial vehicles virtu- 1 Comparison of power and torque curves of gasoline and diesel engines of similar power a kW Effective power output P 100 Prated 1 80 60 2 40 20 0 Fig. In Particulate/smoke emission limits addition. Whereas. for any combination of engine operat. specific air-fuel ratios λ). In addition to optimum air/fuel mixture fore. limits) The fuel-injection system thus plays a de. requires taking account of engine or vehicle- tion limits (i.2 l 4-cylinder 180 2 diesel engine with common-rail fuel 120 injection 60 2 2. the fuel is injected di. it has to take account of the condi. for cars only. passenger car. and circumstances.000 5. Robert Bosch GmbH Basic principles of the diesel engine Operating conditions 21 Operating conditions the correct amount of fuel at the correct time The operating conditions of a diesel engine at the correct pressure are based on a number of process-specific with the correct timing pattern. combustion pressure limits cisive role in engine operation.000 rpm Engine speed n Mmax Maximum torque Prated Rated power . emission restrictions (e. chamber rectly into the highly compressed hot air which causes it to ignite spontaneously. and because of the heterogeneous air/fuel considerations.g. cial vehicle) and from one country to an- ing parameters.000 3. There. smoke content.000 2. the fuel-injection system other. There are prescribed statutory limits for tion of the intake air in terms of pressure particulate emissions and maximum exhaust and temperature. related operating limits such as: with a constant air volume in the cylinder. the diesel engine – in contrast with amount of fuel to be delivered frequently the gasoline engine – is not restricted by igni. commer- Thus. determination of the correct mixture.000 6. at the correct point in the combustion In a diesel engine. They differ according to the type of vehicle (e. It is responsi. 1 b Nm a Power curve 1 b Torque curve 300 240 Mmax Torque M 1 2.000 4.g.e. and required and “even” distribution throughout vehicle or engine-specific load limits the cylinder charge – and it has to perform those tasks at all engine speeds and loads. exhaust temperature limits ble for delivery of the precise amount of fuel engine speed and torque limits. smoke emission only the fuel quantity is regulated. Thus. the lower power must deliver band is tested.3 l 5-cylinder gasoline engine æ SMM0615E 0 1. speed or intermediate-speed governors. If high initial thermal-release peak (without pre. The dimensioning and expected to maintain a constant speed or to durability of the engine and drivetrain com. exhaust temperature of a diesel engine. keep their speed within certain upper and ponents therefore limit the permissible maxi. tion place periodic alternating stresses on the Diesel engines that drive machinery are engine components. bustion chamber. The high thermal stresses placed on the engine components surrounding the hot com- The largest proportion of particulate emis. the fuel supply is not reduced before the en- injection). the partially va. Robert Bosch GmbH 22 Basic principles of the diesel engine Operating conditions ally the entire output range is taken into Exhaust-gas temperature limits consideration. output at a constant engine speed is basically dependent solely on the amount of fuel in- Combustion pressure limits jected. then the engine speed will rise. is absolutely essential on a diesel engine. Conse- produced and this requires a relatively heavy quently. The fact that diesel engines operate on the els of excess air. gine reaches a critical speed. High combustion pressure peaks are rev itself to the point of destruction. diesel engine is increased without a corre- porized fuel mixed with the air burns under sponding increase in the load that it is work- high compression at a rapid rate and with a ing against. jected-fuel quantity means that the power sure of the efficiency of air utilization. localized over-enrichment occurs and this in some cases leads to an increase in Engine speed limits black smoke emissions even at moderate lev. there are variable- the amount of fuel injected. lower limits regardless of the load applied. bustion. The air-fuel ratio usable at basis of excess air with regulation of the in- the statutory full-load smoke limit is a mea. the engine may bustion. As a large part of the air/fuel mixing and cylinder head determine the maximum process only takes place in the course of com. an engine speed limiter or governor engine. If the amount of fuel supplied to a During the ignition process. the heat resistance of the sions is made up of soot particles (black exhaust valves and of the exhaust system smoke). The forces generated during combus. 2 Fuel-injection volume relative to engine speed and load with adjustment for temperature and atmospheric pressure mm 3 Stroke Starting Full power Turbocharged engine Injected-fuel quantity Q Torque matching Conventionally aspirated engine Atmospheric pressure compensation Breakaway Temperature compensation æ UMK0788-1E Idling Engine speed n rpm . This is referred to as “hard” com. mum compression pressure and consequently For such requirements. This has resulted in better Altitude and turbocharger/ specific power output of engines (Figures 3 supercharger pressure limits and 4). sumed that air density decreases by approx. by turbocharger/supercharger pressure). This map (Figure 2) shows the fuel Improvements in precision regulation of quantity in relation to the engine speed and fuel-injection systems and enhancements in load. when the engine is under level. the cylinder charge during dynamic opera- nors which regulate only the idling and tion is lower than in steady-state operation. the engine speed must be infinitely are reduced for that altitude. the engine speed must not be allowed equation. ments described. The intermediate range on which the maximum injection volume is of speeds is controlled by means of the based. it can be as- to drop below the idling speed to a standstill. ate across the entire engine-speed range With turbocharged/supercharged engines. together with the necessary adjustments air charge are factors that allow ever greater for temperature and air-pressure variations. The following two types of governor sys. the performance figures vehicles. Therefore. accuracy in complying with the limits described above. the fuel-injec- Variable-speed governors which are oper. as with high altitudes. In order to re- tem are distinguished: main within the smoke limit. Robert Bosch GmbH Basic principles of the diesel engine Operating conditions 23 On diesel engines used to drive road-going level. a characteristic data map can be defined for the operating range of an Development potential engine. 7% per 1. Idle-speed and maximum-speed gover. the accelerator pedal. In addition. The setting of fuel-injection volumes is generally based on atmospheric pressure at sea 3 Development of diesel engines for 4 Engine speed and torque of car engines mid-range cars with D3 certification 180 Engine versions Torque of largest engine [Nm] 470 N•m/l Torque of smallest engine [Nm] Rated power of largest engine [kW] 150 Maximum specific torque Rated power of smallest engine [kW] 120 250 210 185 172 126 150 145 90 118 123 113 113 101 100 80 70 75 44 æ NMM0625E 59 æ NMM0616E 53 40 40 40 30 60 1953 1961 1968 1976 1984 1995 2000 20 40 60 80 kW/l Fig. justed according to the barometric altitude leased. 4 Year of construction Specific rated power Diesel engines (DI) + Gasoline engines . If the engine is variable by the driver using the accelerator operated at altitudes significantly above sea pedal. As a general guide. fuel volume has to be reduced according to the smaller quantity of air (full load limited Taking into consideration all the require. maximum speeds.000 m of altitude. In other words. the fuel-injection volume must be ad- load or when the accelerator pedal is re. tion volume has to be reduced accordingly. and finishes later at higher speeds than indicated by the purely geometrical calculations. injection (1 mm3 per injection). vehicle speed.8 each cylinder and thus achieves particularly l smooth engine running. Even the the effective stroke under real conditions is minutest variations have a negative effect greater than the calculated effective stroke. the exacting demands on the precision of the fuel consumption of diesel engines is lower fuel-injection system. Thus. Even greater precision is demanded at idling as the fuel displays inertial characteristics speed (5 mm3 per injection) and for pre. in dynamic changes to the effective stroke and a rising or falling fuel-delivery curve. The mathematically calculated injected 0. speed of 2.g. æ UMK0790-1E 1. payload. cylinder peak pressure. it also has to do so for each individual cylinder of a multi-cylinder engine. electrical equipment in use. 37 kW The fuel consumption of a vehicle depends Distance travelled (50 bhp) on a variety of factors (e. under dynamic flow conditions. there are 288.4 load curve is limited by the engine’s smoke limit and at higher speeds by the permissible maximum exhaust-gas/component temper. The delivery rate of a piston pump is cal- rate injections of fuel per hour. The fuel-injection system not only has to Solenoid-valve controlled fuel-injection deliver precisely the right amount of fuel systems also have to take account of the to suit the exact operating conditions at any timing characteristics. By comparison. This can be illustrated than that of gasoline engines (Figure 1). The Electronic Diesel 1 Comparison of cumulative fuel consumption after cold start (10 °C) Control (EDC) system allows the injected- fuel quantity to be adjusted individually for 0. crown by the effective stroke. fuel-injection and regu- (102 bhp) and a specific fuel consumption lation systems have to be matched very pre- of 200 g/kWh demands an overall fuel cisely to one another. As a result. particular moment. 2 0. the full. Furthermore.6 fuel quantity serves as a guide figure for the 1 Fuel consumption dimensioning of a fuel-injection system. On a four-cylinder variety of factors must be considered. 1 ature as well as by the maximum permissible 1 Gasoline engine. a wide supply rate of 15 kg/h.5 l. At lower engine speeds in particular. tire pressure. pump delivery starts sooner has a volume of approximately 30 mm3. each culated by multiplying the area of the piston individual injection of fuel involves a quan.and post-delivery effects” results emission and black smoke levels. 37 kW (50 bhp) 0 2 Diesel engine. a raindrop trolled systems. on the smooth running of the engine.000 sepa. noise This “pre. In port-con- tity of 59 mm3. vehicle.400 rpm. 0. Robert Bosch GmbH 24 Basic principles of the diesel engine Fuel injection system Fuel-injection system route topography. This four-stroke engine turning at an engine can be illustrated by the following example. by the following example. In this regard. . The full-load injected-fuel quantity for Calibrating the regulation systems an engine with a power output of 75 kW The engine. it has to prevent accuracy drift over time. The operating conditions referred to place and air filter condition).2 Fig. driving style. Fuel consumption 0 2 4 6 8 km 1. In principle.1 l. 3 Glow plug . chambers now hardly figure at all among new developments. the special shape of the intake port in the cylinder head creates an air vortex inside of The proportion of direct-injection engines the cylinder. This injection (DI) engines) and places exacting demands on fuel and air deliv- divided combustion chamber (indirect ery. the direct-injection to improve distribution of liquid fuel or air process involves injecting the fuel directly into and fuel vapor inside of the combustion the combustion chamber. In addition to creating effective air turbulence. The positions of the jets have to be optimized to suit the combustion chamber design. they are used in all types a diesel engine. the action of the piston can produce swirl. 1 In practice. direct-injection engines use multihole injectors (1). The shape of the combustion is increasing due to their more economical chamber also contributes to the air flow pat- fuel consumption (up to 20%). 1 virtually exclusively by means of fuel 1 Multihole injector injection and largely dispense with any 2 ω piston recess air-flow effects. and æ UMK0315-1Y systems which control mixture formation Fig. of the diesel engine. part of which is chamber. combustion noise (particularly under accel. heating. squish and turbulence effects that are used As the name suggests. the technology must also ensure that the fuel is delivered in such a way that it is 1 Direct injection “evenly” distributed throughout the combustion chamber so as to facilitate rapid mixing. Fuel atomization. the most widely used at jection. The following technologies are used: vaporization and mixing with the air must undivided combustion chamber (direct therefore take place in rapid succession. During the induction and compression injection (IDI) engines) strokes.e. Of the com- eration) can be reduced to the level of indi. Accordingly. Engines with divided combustion present is the ω piston crown recess. The harsher tern at the end of the compression stroke (i. Robert Bosch GmbH Basic principles of the diesel engine Combustion chambers 25 Combustion chambers Undivided combustion chamber (direct-injection engines) The shape of the combustion chamber is Direct-injection engines (Figure 1) have a one of the decisive factors in determining higher level of efficiency and operate more the quality of combustion and therefore the economically than indirect-injection en- performance and exhaust characteristics of gines. there are two types of direct fuel injection: 2 systems in which mixture formation is assisted by specifically created air-flow effects. 2). bustion chamber designs used over the history rect-injection engines by (minimal) pre-in. In contrast with the indirect-injection engine with its single-jet throttling-pintle injector. Appropriate design of com. at the moment of fuel injection). of commercial vehicles and most modern bustion-chamber geometry combined with diesel cars. Direct fuel injection also requires very 3 high injection pressures (up to 2.000 bar). formed by the shape of the piston crown (piston crown recess. Combustion initiates inside the precombustion chamber. (Figure 2. sures in order to obtain the required short injection times and atomization quality. no effort is expended in Precombustion chamber system creating air-turbulence effects and this is evi. A specially shaped nozzle jets and degree of atomization baffle (3) in the center of the chamber dif- (achieved by small spray-hole apertures). There are two types of indirect-injection A differently shaped precombustion cham- system: ber with a vaporization recess and a differ- the precombustion chamber system and ently shaped and positioned baffle (“spheri- the whirl-chamber system. The short ignition lag and the controlled re- however. that advantage has disappeared. electronic (diesel) engine management and pre-injection are possible. number of pressure (up to 450 bar). æ UMK0313-1Y chamber 3 Spherical pin with baffle surface The ratio of precombustion chamber vol- 4 Connecting channel ume to main combustion chamber volume 5 Glow plug is approx. however. stress. cal pin”) apply a defined degree of swirl to the air that passes from the cylinder into the precombustion chamber during the com- 2 Precombustion chamber system (optimized version) pression stroke. indirect-injection engines are effect with low levels of noise and engine no longer used in new vehicles. A controlled 3 post-glow period of up to 1 minute after a 5 cold start (dependent on coolant tempera- 4 Fig. tion pressures. The fuel is injected ments are placed on the fuel-injection system through a pintle nozzle (1) at a relatively low with regard to nozzle positioning. That was the thoroughly with the air in the main combus- reason why they were used in cars and light tion chamber so that combustion spreads commercial vehicles. thereby raising the tempera- Divided combustion chamber ture and pressure and forcing the partially (indirect injection) combusted air/fuel mixture through chan- For a long time. and is completed. 1 So as not to disrupt the progression of combustion. There it mixes noise and exhaust emissions. it thoroughly with the air. Robert Bosch GmbH 26 Basic principles of the diesel engine Combustion chambers In the latter case. diesel engines with divided nels at the lower end of the precombustion combustion chambers held an advantage chamber and into the main combustion over direct-injection engines in terms of chamber above the piston. 2 ture) helps to improve exhaust-gas charac- 1 Pintle nozzle teristics and reduce engine noise during the 2 Precombustion warm-up period. In the precombustion chamber system. lease of energy produce a “soft” combustion As a result. the dent in smaller gas replacement losses and fuel is injected into a hot precombustion more effective cylinder charging. . At the same chamber recessed into the cylinder head time. the glow plug (5) is positioned on 2 the “lee side” of the air flow. 1/3 to 2/3. Now that high injec. not fuses the jet of fuel that strikes it and mixes to mention extremely high injection pres. far more demanding require. Item 2). The fuel is injected at an angle of 5 degrees to the precombustion chamber axis in the direction of flow of the air. 2 Tangential tion noise is louder than with the precom. Item 2). it vaporizes direct fuel injec- and is absorbed by the air. During the compression stroke. This re. be achieved. combustion is also initi. though in this case swirl chamber. place as completely as possible inside the ated in separate chamber. the losses due to gas flow between the main combustion chamber and the swirl chamber are less than with the precombus. a single-jet nozzle sprays the fuel economical consumption compared with at a low injection pressure against the wall of induced air-flow the piston crown recess. 3 tion chamber system because the connecting channel has a larger cross-section. the air/fuel 3 Swirl-chamber system mixture is forced under pressure through the connecting channel into the cylinder 1 chamber where it is turbulently mixed with the remaining air. The nozzle jet is positioned preventing unburned hydrocarbons (blue so that the jet of fuel enters the swirling air smoke) during the warm-up period. This system thus tion. the air en. therefore. combus. the M sys- uses the heat of the piston recess wall to tem is no longer æ UMK0786-1Y vaporize the fuel. because of its less fuel engines. However. the alignment and shape of the fuel jet sion volume. ditions. connecting bustion chamber system. Another demand is for rapid heating of the tering through the connecting channel is swirl chamber after a cold start. 3 consequent benefits for internal efficiency æ UMK0314-1Y 1 Fuel injector and fuel consumption. low pressure in- deposition (M system) for commercial-vehicle crease and. As soon as combustion starts. The shape of the swirl cham- it accommodates almost the entire compres. ber. flow perpendicular to its axis and meets a hot section of chamber wall on the opposite side of the chamber. Robert Bosch GmbH Basic principles of the diesel engine Combustion chambers 27 Swirl-chamber system It is important that mixture formation takes With this system. If the air flow inside of the used. 2 sults in smaller throttle-effect losses and Fig. channel 3 Glow plug M System In the direct-injection system with recess-wall long combustion period. Nevertheless. With the swirl-chamber system. an extremely homogeneous air/fuel mixture with a . quiet combustion can and fixed-installation diesel engines and multi. This reduces made to swirl and the fuel is injected in the ignition lag and combustion noise as well as swirling air flow. There. The combustion process takes and the position of the glow plug must be place inside a spherical or cylindrical swirl carefully matched to the engine in order to chamber with a tangentially aligned channel obtain optimum mixture formation at all connecting it to the cylinder chamber engine speeds and under all operating con- (Figure 3. combustion chamber is properly adapted. . the fuel standards are less stringent or in some cases Cetane number nonexistent. High cetane number In order to cover the growing demand for Relatively low upper boiling limit diesel fuels. In many other individually below.e. They all have boiling points in keep vehicle emissions within present and the range 160. They are obtained by polyaromatic compounds) content cracking large heavy-oil molecules. 1 Selected EN 590 grading criteria compared with the requirements of the European motor manufacturers European motor vehicle Criterion EN 590 manufacturers Cetane number ≥ 51 ≥ 58 Density 820.840 kg/m3 Table 1 Aromatic compounds content – ≤ 20 % by vol.10 ppm for compliance with 1/1/2003 and Euro IV and V emission limits throughout the Lubricity (HFRR) ≤ 460 µm ≤ 400 µm EU from 1/1/2005. The higher the cetane criteria..845 kg/m3 820.. thermal and catalytic.380 °C (middle distillates).. Some of the most important grading criteria specified by EN 590 are Diesel fuels are distilled from crude oil. Robert Bosch GmbH 28 Basic principles of the diesel engine Diesel fuels Diesel fuels demanding. some of which have a consistent function of fuel-injection systems: decisive effect (see Table 2 at the end of this Good lubricant qualities section). Such criteria help to compounds. countries around the world. the following characteristics are The basic fuel grade is improved by the use particularly important for the service life and of a series of additives. olefins. ments for diesel-fuel grade which are also i-paraffins. i. Low sulfur content (≤ 10 ppm) Quality and grading criteria In addition. It also shows the consist of a large number of different hydro. The requirements for marine and number.. Diesel fuel ignites on average at approximately 350 °C.. the more easily combustible the fixed-installation engines are also much less fuel is. High-quality diesel fuels are characterized parison with gasoline (500 °C) (lower limit by the following features: 250 °C). naphthenes and aromatic subscribed to by Bosch.. the refineries also add “conver.. Low aromatic compounds (particularly cracking products. a sulfur content Boiling point (95 %) ≤ 360 °C ≤ 340 °C of 10 ppm will be available throughout Upper boiling limit – ≤ 350 °C Germany from Sulfur content1) (by mass) ≤ 350 ppm 5. ≤ 1 % by vol. 1) Diesel fuel with Polyaromatic compounds content ≤ 11 % by vol. European motor manufacturers’ require- carbon compounds including n-paraffins. They listed in Table 1 below. for example. which is very early in com. The US standard for diesel fuels The cetane number indicates the ease with ASTM D975. future limits. Absence of free water Low dirt content 16 grading criteria are specified by the standard EN 590 for motor vehicles which now The most important criteria are explained applies throughout Europe. specifies fewer which a diesel fuel ignites and is therefore of criteria and applies less strict limits to these decisive importance. Narrow density and viscosity spread sion products”. . fies narrow tolerance limits for diesel-fuel The proportion of cetane then gives the cetane viscosity. The energy content of diesel fuel per unit of volume increases with density. The boiling range is the temperature range within which the fuel boils. The engine is at low engine speeds in particular and there- then run on a reference fuel made up of a fore also to power deficiencies and hot-start mixture of cetane and α-methylnaphthalene problems. There is a greater density H H C H spread found in fuels around the world than H C C H C C C permitted by EN 590. The requirement of diesel fuel is therefore α-methylnaphthaline (C11 H10) “narrow grade-based density spread”. it will (Figure 1) using the same compression ratio. Paraffin fuel components have a high cetane A low initial boiling point makes a fuel number while aromatic compounds (chiefly suitable for use in cold weather but also cracking products) have a low cetane num. Fuels are sold by volume and delivered to the combustion chamber by fuel-injection systems on the same basis. 1 H H C Carbon H Hydrogen –– Chemical bond . engine performance and soot emission increase. All types Polyaromatic compounds with three or of emission. they diminish if a lower-den. C C C æ SMK1877E H C C H Fig. Robert Bosch GmbH Basic principles of the diesel engine Diesel fuels 29 The cetane number is tested using a standard. particularly NOx. then if it is run on higher-density fuel (based on fuel Cetane (n-hexadecane C16 H34) highly combustible (CZ 100) grade). number (for example. Ignition accelerators can be added to the fuel to improve its cetane number. means a lower cetane number and poor lu- ber. The igni. impair pump function and result in poor The proportion of cetane in the mixture is al. If an engine is designed for use 1 Reference fuels for testing cetane number with a “medium-density” fuel. H H H H H H H H H H H H H H H H H C C C C C C C C C C C C C C C C H sity fuel is used. gives long-chained paraffins poor cold-starting properties but a higher cetane number. as does the but a low cetane number. diminish as more rings also have a high boiling point the cetane number increases. Temperature-dependent H H H H H H H H H H H H H H H H variations in fuel density are compensated for by the EDC system. olefins and naphthenes have bricant properties. a mixture of 52% cetane and 48% α-methylnaphthalene has a Boiling range cetane number of 52). non-combustible (CZ 0) sity sensor could also provide a solution H to the problem. Viscosity ized single-cylinder testing engine. more soot is produced as a by- Density product of combustion. it will lead tion lag is set for the fuel under test by means to leakage losses in the fuel-injection system of a variable compression ratio. Therefore. fuel atomization. A high upper boiling limit a medium cetane number. If the viscosity of a fuel is too low. i-paraffins. matic-compound content of diesel fuel increases. EN 590 speci- tered until the same ignition lag is obtained. As the polyaro- combustion noise. If the viscosity is too high. A den. the fuel such as sand. the vehicle Germany). For this reason. organic components. analysis of diesel fuels reveals higher add flow enhancers to diesel fuel in the win. The ACEA requirement for WSD ≤ 400 µm. i. Frequency Reciprocating Rig) (in which Such wear causes valve leakage which lowers a steel ball is moved rapidly to and fro) the injection pressure and engine perfor- by EN 590 and ISO 12 156-1 and 12156-2. this figure related problems started to occur on distrib. In addition.g. pumps. by adding lubricant additives.60 °C. in varying proportions depending on temperature. it is hydrogenated. tion systems.. Even a fraction of the permis- however. wear. In cold parts of the world. The oil industry was to precision-made high-pressure fuel-injec- able to fully restore the lubricant qualities. 50. At temperatures ≤ 0 °C.. this property is therefore 350 °C. EN 590 permits a maximum water con- cipitate paraffin crystals which can clog up tent of 200 mg/kg. the hydrogenation total of undissolved foreign particles in process also removes the ionic fuel compo. However. A water separator and a water i. In addition Overall contamination refers to the sum to removing sulfur. Robert Bosch GmbH 30 Basic principles of the diesel engine Diesel fuels With a view to avoiding poor cold-starting mined according to the HFRR method of properties (paraffins) and high soot emis.g. the The presence of water in the fuel tank as a oil industry produces winter diesel fuel with result of condensation from the air cannot a CFPP rating (Cold Filter Plugging Point. is too high.200 ppm (by weight) at Cold-weather properties 25. caused by the steel ball) deter- .. tion system and the fuel-filler neck so as to prevent additional water from entering. 460 µm. therefore. is adequate to protect fuel-injection sions (polyaromatic compounds). oil companies ever. maximum of 24 mg/kg. Diameter. how- the fuel filter. mance as well as increasing exhaust particu- A maximum permissible WSD (Wear Scar late emissions. which cannot be dissolved in filter pores. at the seats of solenoid valves). at least –20 °C for solutely essential. e. After the intro. be prevented. the point at which it clogs the filter in sensor on the fuel filter are therefore ab- cold weather) (e. EN 590 permits a duction of low-sulfur diesel fuels. diesel fuels may pre. the fuel. Free wa- size still allows them to pass through the ter. Particularly the very hard sili- utor-type fuel-injection pumps which are cates that occur in mineral dust are harmful lubricated by the fuel.. Lubricant properties (“lubricity”) In order to reduce the sulfur content of Overall contamination diesel fuel. For brand new pumps. Bosch rec- the upper limit of the boiling range should ommends the use of a diesel fuel with a not be too high. it is offset Diesel fuel can absorb water in solution by a lower level of crude-oil exploitation. and also dangerous because it lowers the flash point. however.e. sible overall contamination level of hard Since 1998 lubricity has been standardized particles would produce erosive and abrasive on the basis of the HFRR method (High wear (e. rust and undissolved nents that aid lubrication. Dissolved water does ter to limit crystal formation so that their not harm the fuel-injection system. In many countries. For Arctic regions. But although such a requirement is valuable in Water in diesel fuel terms of combustion efficiency. water concentrations. can cause damage to fuel-lubricated injection pumps within a very short space The previously common practice of adding of time and even when it is present only in gasoline or kerosene is no longer necessary very small quantities. the CFPP is manufacturer must design the tank ventila- substantially lower (as much as –44 °C).e.g. fur in chemically bonded form depending on the quality of the crude oil. tremely complex process. Since the beginning of 2000 the EN 590 Flash point maximum limit for the sulfur content of The “flash point” indicates the storage tem- diesel fuel has been 350 ppm. sulfur-free fuels. tors “coke up” (resulting in restriction of fide (H2S) which is subsequently converted flow). 10 ppm of sulfur. only achieve very good filtration results but also have long replacement intervals can Regardless of the function of the systems help to solve the problem. sulfur reactions would take place and the catalytic converter would 2 Effects of the most important diesel-fuel additives Additives Effect Ignition accelerators (cetane improvers) Increase cetane number Improve Engine starting characteristics Exhaust white-smoke emission Engine noise levels Exhaust emission levels Fuel consumption Detergents Keep nozzles cleaner Flow improvers Improve reliability at low temperatures Table 2 Wax anti-setting additives Improve storage properties at low temperatures Different additives can Lubricity enhancers Reduce fuel-injection component wear especially with have similar effects. into pure sulfur. High-efficiency fuel filters that not its intended function. it is above 55 °C require all diesel fuels to contain less than (Hazard Class A III). used for emission control in the future. sulfur dioxide (SO2) and sulfate particle emis- Sulfur content sions can also be eliminated by the use of Diesel fuels contain varying amounts of sul. especially considering the fact that nated” for the purposes of emission elimina- 100 ml of fuel can contain millions of such tion. Robert Bosch GmbH Basic principles of the diesel engine Diesel fuels 31 A particle size of 6. and therefore incapable of performing particles. (≤ 10 ppm). The coking factor ture in the presence of a catalyst. The initial indicates the degree to which the fuel injec- by-product of this process is hydrogen sul. The sulfur is Coking extracted from the middle distillate by hy. From 2005 perature at which flammable vapors are onwards the EU (European Union) will produced. Their concentra- and have to be run on sulfur-free fuel tion level in the fuel is generally < 1 %. .7 µm in the fuel is be to a greater or lesser degree “contami- critical. Otherwise.. For diesel fuels. Emission-control systems such as NOX Additives in diesel fuel catalytic converters and particulate filters The most important additives and their function on the basis of catalytic effects effects are listed in Table 2.. hydrogenated low-sulfur fuels The arrows indicate the Antifoaming additives Make refuelling easier (reduce tendency to slosh over) effects of each additive Anti-corrosive additives (corrosion inhibitors) Protect the fuel system independently of other components. The coking tendency of a fuel is an ex- drogenation at high pressure and tempera. instead of the NOX and HC reactions. they etable oil methyl ester in Europe is RME do not genuinely belong in this category. . (excessively high injection pressures fore requires the use of large quantities of can damage the fuel-injection pump) solubilizers. Methanol The transesterification of the raw materials can be produced from raw materials con. poor (leakage at seals) lubricating qualities. transesterification of vegetable and animal Diesel-and-water emulsions are also re. harvesting.. Thus. although it should be pointed out free glycerines (deposits. etc. essentially improves their cold-weather taining carbon. CO2 cycle. transesterified vegetable oils fuel-injection system.8). and this would demand substantial modifications to the engine design concept and the Nevertheless. Nor do they represent a closed economy of these concepts. Furthermore. therefore. such as tics (cetane number: 3. the only advantage that can be claimed for the sustainable fuel RME is the 65% maximum fossil-fuel saving.. transport and The advantages of the use of alcohol fuels processing (more than in the case of diesel in diesel engines are their low soot and NOx fuel). still present a large number of problems Alcohols have poor ignition characteris. The best known veg- ferred to as alternative fuels. sugar cane). viscosity and thermal stabil- Brazil). der refinery conditions. sunflower and palm-oil methyl esters. fats using methanol. however. The maximum saving of fossil fuels achieved by using RME is theoretically 65 % (50 % in practice). have inher. oils are rather more suitable than pure veg- Both of these fuels. Figure 1a) that they are practically immiscible without high modulus of elasticity the use of additives. ucts. Alcohol fuels among others.g. etable oils for use as alternative fuels for ent disadvantages in comparison with diesel diesel engines. as energy has to be introduced for sowing the crops. ethanol is extracted from biomass ity. Ultimately. The most important Fatty acid methyl esters are produced by among them are alcohols and vegetable oils. RME is the fuels in their pure forms is to mix them with most suitable in this respect) diesel fuel. the poor ignition characteristics demand the use of a high proportion of Vegetable-oil methyl esters do not offer any ignition accelerators. However. free water in mixtures with diesel insufficient oxidation stability Another possibility instead of using alcohol (chemical contaminants. transesterified vegetable (e. high evaporation heat. high volatility and a corrosion of aluminum and zinc high tendency to produce corrosion. significant advantages with regard to emis- the high proportion of additives reduces the sion levels. In some countries (e. Consequently. high viscosity at low temperatures (high exhaust emissions). emissions. Such a concept there. The alternative fuels methanol and ethanol can also be used in diesel engines. characteristics.g. There are also soya. (Rape seed oil Methyl Ester). a low volumetric elastomer incompatibility calorific value. Robert Bosch GmbH 32 Basic principles of the diesel engine Alternative fuels Alternative fuels FAME FAME (Fatty Acid Methyl Ester) is the Alternative fuels for diesel engines are fuels generic term for vegetable and animal prod- that are not produced from mineral oil un. Robert Bosch GmbH Basic principles of the diesel engine Alternative fuels 33 Since the end of 2000 there has been a draft ter separator. As far pected to come into force by the beginning as is known. For that reason. In many by “contaminated” RME æ SMK1878Y such systems. b Fig. The 1 Damage to a fuel-injection pump caused by poor HC emission levels increase. these emulsions have been tested (not by Bosch) in commercial vehicles with in-line fuel-injection pumps. mechanism caused not be sold on the open market. that water would cause dam- European standard for FAME which is ex. are not necessarily removed by a water sepa- ity standards on offer in the marketplace re. Diesel-and-water emulsions Diesel-and-water emulsions reduce soot and NOx emissions but also lower power output relative to the proportion of water (if the injection system is set up for pure diesel). especially at fuel quality low engine loads and/or when the engine is cold. age to the fuel-injection components. growth of micro-organisms.e. the extremely fine emulsion of 2003. Without a wa. meaning that the water would caused by free wa- vaporize and subsequently condense as free ter (vehicle mileage water within the fuel system. etc. fect. Denso and anti-corrosive additives Bosch indicates that it is likely they will only anti-freeze accept a maximum proportion of 5 % “good lubricant additives quality” RME (i. a The companies Elf and Lubrizol have plans to sell diesel-and-water emulsions under the respective brand names “Aquazole” and “Purinox” for use in closed commercial-vehicle fleets. approx. As far is known.600 km) . emulsifiers to stabilize the emulsion ufacturers Delphi. Until that time the properties of droplets measuring only a few nanometers FAME remain unstandardized and the qual. they can. rator. as defined by the draft biocides or the like for preventing the EU standard) until a standard comes into ef. Apart from that. some vehicle manufacturers have issued RME approvals (in some cases only for new specifically designed fuel- injection pumps with special seals). 5. emissions can be immediately reduced for a limited period without having to take any other measures. the fuel temperature can ex- b Bearing damage ceed 100 °C. Diesel-and-water emul. main widely divergent (ranging from “safe” to “fatal” for the fuel-injection system). on older vehicles. 1 sions are not suitable for more modern fuel. Diesel-and-water emulsions contain numer- A common position statement on FAME ous additives such as issued by the fuel-injection equipment man. The advantage quoted is that. a Deposits on actuator injection systems. Stanadyne. In are fitted on all modern diesel cars and some principle. the (Figure 1): density and the composition (e. aspiration and air-intake systems have the job of the intake air and For that reason. the engine requires percharged. Robert Bosch GmbH 34 Cylinder-charge control systems Overview Cylinder-charge control systems 1) The cylinder charge In diesel engines. camshafts. clean the intake air and affect the flow. trolled by valves operated by one or more mum possible engine power output. Beyond that. Gas exchange is thus con- which the cylinder is charged and the maxi. slow-running ma- injected for full load. only four-stroke engines are relationship between the amount of air with used nowadays. the greater the amount of fuel that can be Apart from very large. the oxy. 1 2 1 Air filter 2 Turbocharger/ supercharger with intercooler 5 3 Engine control unit 4 Exhaust-gas recircu. 6 lation and cooler æ SMM0617Y 5 Swirl flap 6 Engine cylinder 7 Inlet valve 8 Exhaust valve . Valve and combustion-chamber design has a is the mixture of jected and the air mass with which it is major effect on the efficiency of the cylinder gases trapped in mixed are decisive factors in determining charging process (see the chapter “Basic prin- the cylinder when the inlet valves are the torque output and therefore engine per. Systems used on cars are for combustion in the combustion chamber.g. It consists formance and exhaust-gas composition. ciples of the diesel engine”). the closed. both the fuel mass in. Swirl flaps (5) Turbocharger/supercharger (2) Exhaust-gas recirculation system (4) Overview Most diesel engines are turbocharged or su- In order to burn the fuel. Those cylinder-charge control systems made up of the following components cycle. There is thus a direct rine engines. 1 Cylinder-charge control systems on a diesel engine 3 1 4 7 8 Fig. the more oxygen there is available commercial vehicles. Air filter (1) gen content) of the cylinder charge. the systems that control of conditioning the intake air and ensuring the residual burned the cylinder-air charge 1) have an important that the cylinders are properly charged. role to play as well as the fuel-injection sys. Exhaust-gas recirculation systems oxygen which it extracts from the intake air. Systems with variable valve timing are under development. The cylinder-charge control systems are ceding combustion tem. gases from the pre. not transferrable to commercial vehicles. The mass concentration in the in. every two to four or. ticles entering the engine and the engine oil and thereby reduces the wear on compo. Around 75% of the particles (based Generally cellulose-fiber based. 2 Prevailing particle sizes encountered in road traffic nents such as bearings. Filters of inadequate surface. Industrial emissions ter housings are also capable of preventing Diesel soot the ingress of water in heavy rain. The dust tangular or cylindrical. i. quality have greater dust passage rates under tention capacities are always preferable when such circumstances. large flow volumes with low particle concentrations need to be efficiently filtered. This might otherwise cause incorrect readings resulting in higher fuel Bacteria consumption and pollutant emission levels Dust above the allowable limits. in some cases. up to 99. piston rings and cylinder walls. Abraded matter specification air-filter element designs in combination with appropriately shaped fil.8% (cars) and 99. which may be rec- widely with regard to particle size. Such figures must be capable of generally deep-bed filters which – in con. the filter on mass) are in the size range from 5 µm to medium is compressed and impregnated to 100 µm. pressure losses Typical air contaminants are illustrated can be kept to a minimum and the high fil- in Figure 2. grains). Deep-bed filters with high dust re. or when the The air filter prevents mineral dust and par. For a car over a period of ten vals specified by the vehicle manufacturer years it may range from the extremes of a (for cars.01 0.000 km or every 90.95% (commercial cles contained in the intake air. give it the required structural strength.000 km. even every six years. Robert Bosch GmbH Cylinder-charge control systems Intake air filters 35 Intake air filters Air filters which incorporate the latest technology achieve total mass filtration rates of Intake air filters reduce the amount of parti. motorway ter elements have to be replaced at the inter- or dirt track).001 0. wet take air depends heavily on the environment rigidity and resistance to chemicals.1 1 10 m 100 Particle size . They are vehicles). consist of a filter particles drawn in together with the intake medium that is folded so that the maximum air have a diameter of between 0. Special high. few grams to several kilograms of dust. The fil- in which the vehicle is used (e. The filter elements.g.000 to 60. It also protects the sensitive Pollen air-mass meter by preventing dust being Viruses deposited on it. being maintained under all prevailing contrast with surface filters – trap the particles ditions including the dynamic conditions in the internal structure of the filter element that exist in the air-intake system of an rather than obstructing their passage on the engine (pulsation). every 40.01 µm possible filter surface area can be accommo- (mostly soot particles) and 2 mm (sand dated within the smallest possible space.e. The filter elements are individually designed for each engine. In that way. They consist of particles from tration rates are not dependent on the flow both natural and artificial sources and vary rate. back pressure reaches 20 mbar). Aerosols Fog æ UKH0376-1E Oil spray 0. new air-filter media. Robert Bosch GmbH 36 Cylinder-charge control systems Intake air filters 3 Photograph of a filter medium made of synthetic The demands for small and highly efficient fibers taken using an electron microscope filter elements (smaller space requirements) that also offer longer servicing intervals is the driving force behind the development of innovative.g. paper with melt-blown layer) and special nano-fiber filter media which Fig. Source: Freudenberg Vliesstoffe KG 4 Air-intake module for a car (example) 1 6 2 3 5 Fig. New air- filter media made of synthetic fibers which have substantially improved performance figures in some cases are already entering production. Figure 3 shows a photograph of a synthetic high-performance filter medium (felt) with continuously increasing density and decreasing fiber diameter across the filter section from the input side to the output side. 3 consist of a relatively coarse base layer made æ NMM0624Y The arrows indicate the of cellulose to which ultra-thin fibers with direction of flow of the intake air diameters of only 30 to 40 nm are applied. 4 1 Housing lid 4 2 Filter element æ SMM0619Y 3 Filter housing 4 Air-intake module 5 Intake duct 6 Intake duct . Better results than with purely cellulose- based media can be achieved with composite materials (e. the individual components can machines. With In countries with high levels of atmospheric the aid of this type of overall system opti. a pre-filter is fitted upstream of the be better matched to one another. thereby sub- output restrictions. 5 Housing partment. In addition to having. dust. oval as well as stepped and trape. In its most simple form. . The pre-filter filters out coarse- to comply with the ever stricter noise. However. it incorporates all air-intake ducts (5 viously mentioned. heavy dust particles. a very high filtration rate. grained. and on construction and agricultural mization. Previously. as pre- (2). similar to diesel soot filters. filter element. air-filter housings were almost 2 exclusively designed as “muffler filters”. are soon to be introduced on the market. pipes in between for noise reduction. the stantially increasing the service life of the fine engine control unit is integrated in the air. In this example. it is a intake system so that the air flow cools the ring of deflector vanes which set the air flow electronic circuitry. And that results in very slim filters 1 Air outlet 2 Air inlet æ SMM0618Y which can be integrated in the engine trim 3 Filter element covers while the mufflers are placed in less 4 Supporting tube accessible positions inside the engine com. 6 Dust collector Air filters for cars Air filters for commercial vehicles Figure 4 shows a complete air-intake module Figure 5 shows an easy-to-maintain and for a car. The resulting centrifugal force separates out the coarse dust particles. into a rotating motion. only mini-cyclone pre-filter batteries optimized for use in conjunction with the main filter element can properly utilize the potential of centrifugal separators in commercial-vehicle air filters. 5 4 3 Their large volume was designed for the supplementary function of reducing air intake noise. and 6) and the air-intake module (4) as well the elements for this filter are dimensioned as Helmholtz resonators and lambda quarter for servicing intervals of over 100.000 km. Robert Bosch GmbH Cylinder-charge control systems Intake air filters 37 New folded structures with alternately sealed 5 Paper air filter for commercial vehicles (example) channels. 5 in size. the two functions of filtration and engine-noise reduction are increasingly separated and the different components independently optimized. Conical. This helps filter element. This 6 means that the filter housing can be reduced Fig. In addition to the air-filter housing weight-optimized plastic air filter for com- (1 and 3) with the cylindrical filter element mercial vehicles. 1 zoidal geometries add to the range of shapes available in order to optimize use of the space under the hood which is becoming ever more confined. Nowadays. cial-vehicle engines output are increased at higher engine were built in 1938. in combi- 40 % (the patent the flap opens. are currently used on some car engines. or supercharged engine. a further increase in mean pressure (and therefore torque) is achieved by higher turbocharger 1 Intake-port shutoff (example) pressures and lower compression. the turbo- 1 charger is itself a type of supercharger. Such “intake-port shutoff ” systems The diesel engine is particularly suited to They became estab. The first tur- though the intake port (5). results in a higher power bocharged commer. 1 4 1 Intake-valve Volumetric efficiency æ NMM0555Y 2 Swirl port Volumetric efficiency refers to the relation- 3 Engine cylinder 4 Piston ship of the actual air charge trapped inside 5 Intake-port the cylinder to the theoretical air charge 6 Flap determined by the cylinder capacity under . it has also been mance. the air is forced into the a turbocharger in closed at low engine speeds. This produces cylinders under pressure in a turbocharged 1925 – it boosted a large degree of swirl combined with suffi. In the cars 2). but is offset by poorer cold-starting characteristics. cles. the cylinder charge and the engine power yield from the same engine capacity. the swirl can be regulated according adopted for fast-running diesel engines in the Swiss Alfred Büchi who first suc- to varying operating requirements. turbochargers and superchargers 1) Even the pioneers of automotive engi- Swirl flaps Turbochargers and neering. the 2 terms turbocharger and supercharger are now generally used to distinguish between 3 6 different methods of operation. Although. speeds. At high speeds. ture of fuel and air. With larger commercial-vehicle engines. while the term supercharger generally refers only to one that is driven directly by the engine (and usually by the crankshaft). strictly speaking. the flap (6) is aspirated engine. mass of the cylinder charge and. But it was nels. Using appropriate flaps and chan. In more recent times. This means that jected fuel mass. and it can be economically 2) It became widely combined with a supercharger/turbocharger established from because of its quality-based method of control. This increases the power output by cient air flow to the cylinder. allowing unrestricted air flow nation with a correspondingly greater in- was registered in 1905). In contrast to a conventionally cessfully produced example shown in Figure 1. assisted aspiration as its compressed cylinder lished by the early charge consists only of air rather than a mix- 1950s. Fig. considered on mixture formation. so that 5 the term turbocharger is used to refer to a supercharger driven by the flow of exhaust gas from the engine. the 1970s onwards. That rotating motion for fixed installations and marine propul- intake air in order enables better mixing of fuel and air to be sion systems as well as on commercial vehi- to improve perfor- achieved. The term “swirl” ers or superchargers has been around for the possibility of refers to a circular motion of the intake air many years1) on large-scale diesel engines precompressing the inside the cylinder. Gottlieb The pattern of air flow inside the cylinders superchargers Daimler (1885) and Rudolf Diesel of a diesel engine has a fundamental effect Assisted aspiration by means of turbocharg- (1896). Robert Bosch GmbH 38 Cylinder-charge control systems Swirl flaps. At the relatively low speeds at which diesel engines run. at low to medium engine speeds. tics and better control characteristics on the part Dynamic supercharging of the exhaust-gas recirculation system. The ad- assisted aspiration.. it is now increasingly Since virtually all modern diesel engines are used to improve the maximum torque figure equipped with turbochargers. power-to-weight ratio.013 hPa. In diesel engines. 2 Turbocharger with variable turbine geometry 8 1 7 6 5 Fig.0. the creation of swirl effects and commercial vehicles as well as on large. This is par- fit that could be achieved would be under ticularly true in connection with systems in non steady-state operating conditions where which the turbocharger pressure is electron- the turbocharger has not reached full deliv. ery pressure. the intake manifold on a diesel 1. In addition. engines to achieve high torque and power ution of the air charge between all cylinders output with a good level of engine efficiency. inside the cylinders is also of importance. ically controlled. vantages of this are bocharged diesel engines. Of the methods of assisted aspiration. Dynamic supercharg. the ing effects of this type are less important in exhaust-gas-driven turbocharger is by far diesel engines than they are for gasoline en. This method of as- gines. temperature T0 = 273 K) without engine is kept as short as possible. the volumetric improved dynamic response characteris- efficiency is in the range 0. the most widely used.85. the only bene. Robert Bosch GmbH Cylinder-charge control systems Turbochargers and superchargers 39 standard conditions (air pressure p0 = In general. 2 1 Exhaust inlet 2 Turbine 3 Deflector blades 4 4 Vacuum tube æ SMM0620Y 5 Adjusting ring 6 Lubricant supply connection 2 3 7 Intake-air inlet 8 Intake-air outlet . designing the intake manifold Whereas the turbocharger was originally specifically to obtain dynamic supercharging conceived as a means of improving the effects would require it to be extremely long.. the main emphasis sisted aspiration enables even small-capacity of intake-manifold design is on even distrib. A degree of supercharging can be achieved simply by the utilization of dynamic effects Turbocharging in the intake manifold. heavy-duty marine and locomotive engines. and distribution of the recirculated exhaust Turbochargers are used on engines for cars gas.3. For supercharged/tur. Robert Bosch GmbH 40 Cylinder-charge control systems Turbochargers and superchargers Design and method of operation On large-scale engines, axial-flow turbines The hot exhaust gas expelled under pressure are also used. In that case, the exhaust gas from an internal-combustion engine repre- flows through the turbine in an axial direc- sents a substantial loss of energy. It makes tion. Axial-flow turbines are more efficient sense, therefore, to utilize some of that energy on such engines and are cheaper to produce to generate pressure in the intake manifold. than radial-flow turbines. For car and commercial-vehicle engines, the radial-flow tur- The turbocharger (Figure 3) is a combina- bine is more economical. tion of two fluid-flow devices: Because of the exhaust-gas back pressure a turbine (7) that is driven by the flow of that builds up upstream of the turbine, the exhaust gas, and engine has to work harder to expel the ex- a compressor (2) that is directly coupled haust gas on the exhaust stroke. Neverthe- with the turbine by means of a shaft (11) less, the engine efficiency across broad areas and which compresses the intake air. of the characteristic-data map is greater. The hot exhaust gas flows over the turbine For fixed-installation engines running at and by so doing forces it to rotate at high constant speed, the turbine and turbocharger speeds (in diesel engines, up to around characteristics can be tuned to a high level 200,000 rpm). The inward-facing blades of of efficiency and turbocharger pressure. Tur- the turbine divert the flow of gas into the bocharger design becomes more complicated center from where it passes out to the side when it is applied to motor-vehicle engines (8, radial-flow turbine). The connecting that do not run under steady-state condi- shaft drives the radial-flow compressor. This tions - because they are expected to produce is the exact reverse of the turbine: The intake high torque levels particularly when acceler- air (3) is drawn in at the center of the com- ating from slow speeds. Low exhaust temper- pressor and is driven outwards by the blades atures, low exhaust-flow volumes and the in- of the impeller so that it is compressed (4). ertia of the turbocharger itself all contribute 3 Commercial-vehicle turbocharger with twin-flow turbine 4 5 Fig. 3 6 11 Compressor housing 1 12 Centrifugal compressor 7 2 13 Intake air 14 Compressed 3 11 8 intake air 15 Lubricant inlet 9 16 Turbine housing 17 Turbine 18 Exhaust outflow æ UMM0516-1Y 19 Bearing housing 12 10 Exhaust inflow 11 Shaft 10 12 Lubricant return outlet Robert Bosch GmbH Cylinder-charge control systems Turbochargers and superchargers 41 to a slow build-up of pressure in the com- to be prevented because of the fire risk – tur- pressor at the start of acceleration. On turbochargers are water-cooled or enclosed in bocharged car engines, this phenomenon heat-insulating material. Turbochargers for is referred to as “turbo lag”. gasoline engines, where the exhaust-gas tem- Because of this effect, turbochargers with peratures can be 200...300 °C higher than on a low inertial mass that respond at lower diesel engines, may also be water-cooled. exhaust-gas flow rates have been developed especially for cars and commercial vehicles. Designs Engine responsiveness is substantially im- Engines need to be able to generate high proved by using such turbochargers – par- torque even at low speeds. For that reason, ticularly at low engine speeds. turbochargers are designed for low exhaust- gas mass flow rates (e.g. full load at an engine A distinction is made between two methods speed of n ≤ 1,800 rpm). To prevent the tur- of turbocharging. bocharger from overloading the engine at Constant-pressure turbocharging involves the higher exhaust-gas mass flow rates, or being use of an exhaust-gas accumulator upstream damaged itself, the turbocharger pressure has of the turbine to smooth out the pressure to be controlled. There are three turbo- pulsations in the exhaust system. As a result, charger designs which can achieve this: the turbine can accommodate a higher ex- the wastegate turbocharger haust-gas flow rate at a lower pressure at high the variable-turbine-geometry tur- engine speeds. As the exhaust-gas back pres- bocharger, and sure that the engine is working against is the variable-inlet-valve turbocharger. lower under those operating conditions, fuel consumption is also lower. Constant-pressure Wastegate turbocharger (Figure 4) turbocharging is used for large-scale marine, At higher engine speeds or loads, part of the generator and fixed-installation engines. exhaust flow is diverted past the turbine by a bypass valve – the “wastegate” (5). This re- Pulse turbocharging utilizes the kinetic energy duces the exhaust-gas flow passing through of the pressure pulsations caused by the expulsion of the exhaust gas from the cylinders. 4 Turbocharger with wastegate Pulse turbocharging achieves higher torques at lower engine speeds. It is the principle used by turbochargers for cars and commer- 9 cial vehicles. Separate exhaust manifolds are 7 used for different banks of cylinders to prevent individual cylinders from interfering with each other during gas exchange, e.g. two groups of three cylinders on a six-cylinder 6 Fig. 4 engine. If twin-flow turbines – which have 8 4 3 1 Charge-pressure two outer channels – are used (Figure 3), actuator the exhaust flows are kept separate in the 2 Vacuum pump 5 turbocharger as well. 3 Pressure actuator 4 Turbocharger In order to obtain good response characteris- 5 Wastegate tics, the turbocharger is positioned as close as 1 2 (bypass valve) æ UMK1551-9Y 6 Exhaust flow possible to the exhaust valves in the flow of 7 Intake air flow hot exhaust gas. It therefore has to be made 8 Turbine of highly durable materials. On ships – 9 Centrifugal where hot surfaces in the engine room have compressor Robert Bosch GmbH 42 Cylinder-charge control systems Turbochargers and superchargers the turbine and lowers the exhaust-gas back reach the turbine (variation of geometry). pressure, thereby preventing excessive turbo- By so doing, they adjust the exhaust-gas charger speed. pressure acting on the turbine in response At low engine speeds or loads, the waste- to the required turbocharger pressure. gate closes and the entire exhaust flow passes through and drives the turbine. At low engine speeds or loads, they allow only The wastegate usually takes the form of a a small gap for the exhaust gas to pass through flap integrated in the turbine housing. In the so that the exhaust-gas back pressure in- early days of turbocharger design, a poppet creases. The exhaust-gas flow velocity through valve was used in a separate housing parallel the turbine is then higher so that the turbine to the turbine. turns at a higher speed (a). In addition, the exhaust-gas flow is directed at the outer ends of The wastegate is operated by an electro- the turbine blades. This generates more lever- pneumatic charge-pressure actuator (1). age which in turn produces greater torque. That actuator is an electrically operated 3/2-way valve that is connected to a vacuum At high engine speeds or loads, the deflector pump (2). In its neutral position (de-ener- blades open up a larger gap for the exhaust gized) it allows atmospheric pressure to act gas to flow through with the result that the on the pressure actuator (3). The spring in flow velocity is lower (b). Consequently, the the pressure actuator opens the wastegate. turbocharger turns more slowly if the flow If a current is applied to the charge-pres- volume remains the same, or else its speed sure actuator by the engine control unit, it does not increase as much if the flow vol- opens the connection between the pressure ume increases. In that way, the turbocharger actuator and the vacuum pump so that the pressure is limited. diaphragm is drawn back against the action of the spring. The wastegate closes and the 5 Variable turbine geometry of VTG turbocharger turbocharger speed increases. The turbocharger is designed in such a a 1 2 3 4 5 way that the wastegate will always open if the control system fails. This insures that, at high engine speeds, excessive turbocharger pressure which might damage the engine or the turbocharger itself cannot be produced. 6 Fig. 5 On gasoline engines, sufficient vacuum is cre- a Deflector blade ated by the intake manifold. Therefore, unlike setting for high tur- diesel engines, they do not require a vacuum bocharger pressure pump. Both types of engine may also use a b Deflector blade purely electrical wastegate actuator. b setting for low turbocharger pressure Variable-turbine-geometry (VTG) 1 Turbine turbocharger (Figure 5) 2 Adjusting ring Varying the rate of gas flow through the tur- 3 Deflector blade bine by means of variable turbine geometry 4 Adjusting lever (VTG) is another method by which the ex- æ UMM0594Y 5 Pneumatic actuator haust-gas flow rate can be limited at high 6 Exhaust flow engine speeds. The adjustable deflector – High flow rate blades (3) alter the size of the gap through – Low flow rate which the exhaust gas flows in order to ables. There is merely a loss turbine (1). of power at low engine speeds. an intake slide valve (4) alters trols the actuator. used on small car engines. if the control system fails. The engine control unit module controls the a 1 2 3 4 5 6 valve setting by means of a pneumatic actuator. and consequently results in the turbocharger nor the engine suffers a high speed of rotation on the part of the damage as a result. It has not been sets the deflector blades to the desired angle able to establish itself as the preferred choice by operating them either directly using ad. b Fig. 6 a Only one intake port open b Both intake ports open 1 Turbine æ UMM0552-1Y 2 1st intake port 3 2nd intake port 4 Inlet slide valve 5 Bypass channel 6 Valve actuator . When the required turbocharger pressure is reached. ports (2. for gasoline engines because of the high justing levers (4) attached to the blades or thermal stresses and the higher exhaust indirectly by means of adjuster cams. At low engine speeds or loads. The small in- The VTG turbocharger is fully open in its let aperture produces high exhaust-gas back neutral position and therefore inherently pressure combined with a high exhaust-gas safe. or alternatively by an The variable-intake-valve turbocharger is electric motor with position feedback (posi. The engine control unit con. the intake valve gradually opens the second intake port (3). There is also a bypass channel (5) integrated in the turbine housing so that virtually the entire exhaust gas flow can be diverted past the turbine in order to obtain a very low turbocharger pressure. only one of the intake ports is open (2). On this type of tion sensor). This used on diesel engines today. 3). i. Thus the turbocharger the cross-section of the inlet flow to the tur- pressure can be adjusted to the optimum bine by opening one or both of the intake setting in response to a range of input vari. neither flow velocity. adjusting ring is operated by a pneumatic actuator (5) to which positive or negative Variable-intake-valve turbocharger (Figure 6) pressure is applied. turbocharger.e. The temperatures encountered. Robert Bosch GmbH Cylinder-charge control systems Turbochargers and superchargers 43 The deflector blade angle is adjusted very This is the type of turbocharger most widely simply by turning an adjuster ring (2). The flow velocity Method of operation of variable-intake-valve of the exhaust gas – and therefore the tur- 6 turbocharger bine speed and the turbocharger pressure – then gradually reduce. quently. lighter weight and smaller dimensions. the turbo is shifted to a position where frictional losses lag can be minimized by utilizing the dy- are lower. with therefore. the use of turbochargers with variable turbine geometry provides a 7 Power and torque curves for a turbocharged engine means of significantly reducing turbo lag. the “turbo lag” effect occurs. compared with a conventionally aspirated engine Another design variation is the electrically b assisted turbocharger which is aided by an electric motor. aspirated engine under steady-state consumption Specific fuel E conditions Lower æ SMM0621E b Turbocharged en- D consumption gine under steady- state conditions c Turbocharged 1/4 1/2 3/4 1 n engine under Specific engine speed n rated dynamic conditions . At that aspirated engine of equal power. The motor accelerates the Engine power output P B C impeller on the compressor side of the tur- Equal More bocharger independently of the exhaust-gas a power power at lower flow through the turbine. the turbocharger’s response characteristics. the power output at a given speed the torque output remains similar to that is higher (A – B) at the same specific fuel of a conventionally aspirated engine even at consumption. Under dynamic operating conditions. the design of a the turbocharger must ensure that the tur- Fig. The result of this is lower fuel namic supercharging effect. This partially offsets the Torque M c lower density of air. the useful speed range (Figure 7). the usable energy from the exhaust- advantage of a turbocharged engine is its gas flow is insufficient to drive the turbine. On acceleration from slow speeds. torque characteristics (B – C). However. On diesel engines. It No turbocharger pressure is generated in also has better torque characteristics within this way. the point at which a required amount of power is produced On gasoline engines in particular. the prime point. the basic torque Downsizing of a turbocharged engine is similar to that When compared with a conventionally of a conventionally aspirated engine. medium engine speeds (c). Robert Bosch GmbH 44 Cylinder-charge control systems Turbochargers and superchargers Advantages and disadvantages Torque curve of turbocharging At very low engine speeds. This is because The same amount of power is available at of the delay in the build-up of the exhaust- a lower engine speed because of the superior gas flow. This type of turbocharger is currently in the course of development. a turbocharged engine. Conse. 7 a Conventionally bine does not over-rev in such conditions. speed Equal The response of turbocharged engines as altitude increases is very good because the pressure differential is greater at lower at- b mospheric pressure. This improves consumption (E – D). thereby reducing A speed turbo lag. Thus. superchargers are rarely used on diesel engines. 9 Helical-vane supercharger (Figure 10): Two 4 1 Inlet valve inter-meshing helical vanes (4) compress 2 Outlet valve the air. 10 1 Drive pulley 3 4 2 Intake air 3 Compressed air 4 Helical vane . æ NMM0623Y Fig. 3 Diaphragm 4 Drive shaft 10 Helical-vane supercharger 2 1 æ UMM0592-1Y Fig. Compared with 1 2 turbochargers. Robert Bosch GmbH Cylinder-charge control systems Turbochargers and superchargers 45 Supercharging 8 Principle of reciprocating-piston supercharger A supercharger consists of a compressor dri. 3 Positive-displacement supercharger The most common type of supercharger is the positive-displacement supercharger. The engine and the compressor are generally rigidly linked. by a belt drive system. 1 2 Reciprocating-piston supercharger: This type 3 has either a rigid piston (Figure 8) or a diaphragm (Figure 9). It is used mainly on small and medium-sized car Fig. The 9 Principle of reciprocating-piston supercharger with diaphragm types used on diesel engines are the reciprocating-piston supercharger and the helical- vane supercharger. the air is compressed inside the compressor.g. e. A piston (similar to an engine piston) compresses the air which then passes through an outlet valve to the engine cylinder. 8 engines. with rigid piston ven directly by the engine. The following types of supercharger 4 1 Inlet valve æ NMM0622Y are used on diesel engines: 2 Outlet valve 5 3 Piston Positive-displacement supercharger with 4 Drive shaft internal compression 5 Casing With this type of supercharger. a system of gears. to a gear pump and in that way compress the intake air. higher engine 1 Housing torque and better response characteristics are 2 Rotary vane obtained than with a turbocharger. those advantages are offset by a some- 1 Low-pressure stage 4 what higher rate of fuel consumption than (turbocharger with with a turbocharger. 10.15 kW for cars) is not available as effective engine Fig. æ UMM0553-1Y intercooler) 1 This. If variable- speed gearing is used. the necessary power output for driving the compressor (approx.. The remainder flows through the bypass and is returned to the intake side. Another 5 Bypass valve disadvantage of the supercharger is the greater 6 Bypass pipe amount of space it requires. This means that under Fig. the air is perchargers. That disadvantage is mit- 5 2 intercooler) igated if the compressor can be disconnected 2 High-pressure stage 6 at low engine speeds and loads by means of (turbocharger with a clutch operated by the engine control unit. In order to obtain the high pe- diesel engines was the Rootes supercharger ripheral velocity required. they are driven via (Figure 11) which was fitted to some two. however. Controlling supercharger pressure The pressure generated by a supercharger can be controlled by means of a bypass. . A proportion of the compressed air flow enters 11 Cross-section of Rootes supercharger the cylinder and determines the cylinder charge. rotary vanes (2) linked by gears rotate in Centrifugal turbochargers are rarely used on contact with one another in similar fashion medium-sized or larger car engines. Robert Bosch GmbH 46 Cylinder-charge control systems Turbochargers and superchargers Positive-displacement supercharger without Centrifugal supercharger internal compression In addition to the positive-displacement su- With this type of supercharger. Advantages and disadvantages of supercharging Because the supercharger is driven directly by 2 the crankshaft. makes the super- 3 Intake manifold 4 Exhaust manifold charger more expensive to produce. This type of supercharger stroke diesels. on the other hand. 1 The bypass valve is controlled by the engine control unit. there are also centrifugal super- compressed outside of the supercharger chargers (centrifugal-flow compressors) in by the action of the fluid flow generated. 3 Since. 11 dynamic operating conditions.. offers good volumetric efficiency over a wide range of speeds and can be seen as an alter- Rootes supercharger: Two contra-rotating native to the turbocharger for small engines. 12 output. the engine response to 12 Two-stage turbocharging (schematic) load changes can also be improved. which the compressor is similar to that in a The only example of this type to be used on turbocharger. any increase in engine speed is instantaneously mirrored by an increase æ UMM0509-1Y in compressor speed. the electric booster supplies the engine Sequential supercharging involves the use of with extra air. both steady-state and dynamic operating conditions and at the same time improve Electric booster the specific fuel consumption of the engine. This is an additional compressor mounted Two methods of turbocharging have proved upstream of the turbocharger. A particularly Reduced knocking tendency on the part high level of compressor efficiency can be of gasoline engines achieved with two-stage turbocharging. 180 °C). generated during the compression stroke. . Conse. An intercooler dominantly used on marine propulsion between the turbocharger and the engine is systems or generator engines. hot air is less dense than cold air. sequential supercharging is pre. torque and therefore greater power output Items 1 and 2). In circuit. the bypass valve Intercoolers achieve heat extraction either gradually opens until eventually only the by cooling the air or with a separate coolant low-pressure turbocharger is operating. air also heats up (to as much as optimum levels of operation can be ob. so that both turbochargers are Small reduction in NOx emissions as a re- working. under otherwise identical contained. It means that there two differently dimensioned turbochargers is more oxygen available for combustion. Thus. Since. the turbocharging system adjusts Multistage turbocharging is an improvement evenly to the engine’s requirements. the supercharger sequencing control system. the relatively small high-pressure This has a number of advantages: compressor in the second turbocharger is op. Intercooling consequently Controlled two-stage turbocharging helps to further improve the efficiency of the Controlled two-stage turbocharging involves cylinder charging process. two intercoolers (Figure 12. a high-pressure turbocharger (2). The first turbocharger is a is available at a given engine speed. Because of the added expense of the ditions. sult of the lower combustion temperature opment of a high turbocharger pressure. As engine speed increases. Robert Bosch GmbH Cylinder-charge control systems Turbochargers and superchargers 47 Multistage turbocharging this way. automotive applications because of its jective here is to improve air supply under straightforward control characteristics. effect on the cylinder charge. It is similar in successful in this respect. higher temperature of the air has a negative however. in comparison with a single Intercooling larger turbocharger which is geared to the In the process of being compressed by the engine’s rated power output. so that it can deliver the sion on the part of diesel engines required air-mass flow rate. two or more turbocharger. The ob. design to the turbocharger’s compressor but is driven by an electric motor. quently. Greater thermal efficiency and therefore erating at a higher input pressure with a low lower fuel consumption and soot emis- volumetric flow rate. which successively cut in as engine load increases. Under acceler- Sequential supercharging ation. The The lower temperature of the air entering intake air first undergoes precompression the cylinder also reduces the temperatures by the low-pressure turbocharger. Lower thermal stresses on the cylinder At lower engine speeds. thereby improving its response multiple turbochargers connected in parallel characteristics at low speeds in particular. This provides for very rapid devel. ideally. on single-stage turbocharging in that power This method of turbocharging is used in limits can be significantly extended. connected in series with a controlled bypass with the result that a higher maximum and. therefore used to reduce the temperature of the compressed air. low-pressure turbocharger (1) and the second. the bypass valve block/head (5) is closed. In that way. If the gearing ratio between the engine and the pressure. A vane rotor (2) driven by the engine rotates inside a The vane rotor and exhaust pipe arrangement cylindrical housing. It can also 6 Low-pressure 3 produce torque response exhaust 7 Vane rotor characteristics that are not 8 Vents in housing . The exchange of energy takes place at the speed of sound. The ne- air flow (5). since an optimized turbocharger using the lat- The characteristic feature of pressure-wave est technology provides the best compromise superchargers is the direct exchange of en. Specially shaped vane a large amount of space in comparison with enclosures created by the rotor vanes insure other methods of supercharging. Consequently. This makes that the pressure waves of the exhaust-gas it difficult to accommodate in engine compart- flow (4) produce a pressure rise in the intake ments where space is at a premium. 4 wave supercharger is invariable. An integral governing mechanism cessity of balancing the exhaust-gas oscilla- regulates supercharger pressure according tions at all engine speeds and loads demands to engine requirements. the super- 1 High-pressure charger can be made efficient intake air over a relatively broad operat. the exchange of energy is optimum only for a specific point on the power curve. Robert Bosch GmbH 48 Cylinder-charge control systems Pressure-wave superchargers Pressure-wave superchargers A variation of the supercharger for car engines obtainable in the same way with other super- is the pressure-wave supercharger known by charging methods. 7 2 Drive belt ing range. 8 æ UMM0517-1Y exhaust state operation. a very costly control system. the proprietary name “Comprex®”. this type of super- ergy between the exhaust and intake air flows charger has failed to establish itself. 5 But by the use of appropriate “pockets” in the ends of the 1 housing and clever design 6 of the vane rotor. without any intermediate mechanical components. between function and cost. A pres. The system is not subject to the negative effects of turbo lag. the 3 Low-pressure pressure-wave supercharger 2 intake air 4 Engine piston can achieve good supercharg- 5 High-pressure ing characteristics for steady. Pressure-wave superchargers sure-wave supercharger – like other types of supercharger – responds instantaneously to load changes. the ends of which each of a pressure-wave supercharger requires have two vents (7). in order to ignition characteris- Addition of recirculated exhaust gas to the effect exhaust-gas recirculation.25 % for com. it closes off a channel con. The inert gas ularly effective. quired negative pressure differential must the levels of the emissions that occur as a be used. the turbocharger turbine on a commercial ve. The size of that proportion can be deliberately deter. mined by valve timing.e. be up to 50 % on cars and 5. downstream of the turbocharger compressor however. Under normal circumstances. Exhaust-gas recirculation can be downstream of the turbocharger compressor. high loads whenever a pressure pulse is cre- haust-gas recirculation is an absolute necessity. NOx-reducing effect of exhaust-gas recirculation is based on three mechanisms: Exhaust-gas recirculation in commercial Reduction of the oxygen concentration vehicles in the combustion chamber In the future exhaust-gas recirculation will Reduction of the amount of exhaust gas also be used on commercial vehicles (heavy- expelled. Another possibility is a flutter valve result of insufficient air (CO. tics and combustion propagation. Today it is used amount of burned gas left in the cylinder on most car diesel engines. 1) Constituents of the the inert gases1) H2O and CO2. Robert Bosch GmbH Cylinder-charge control systems Exhaust-gas recirculation 49 Exhaust-gas recirculation Exhaust-gas recirculation in cars Exhaust-gas recirculation was first intro- After combustion. tion. This will be the case at quently. The recirculation). a lambda sensor sensor or the signal from To make the EGR valve operate precisely. and duty) in order to obtain lower NOx emis- Reduction of temperature by virtue of the sions. do not the exhaust-gas back pressure upstream of take part in combus- Recirculation of cooled exhaust gas is partic. Conse. it has a differential pressure sensor on a venturi to be designed to be resistant to deposits. Fuel consumption also increases if haust is greater than in the intake duct so that too much exhaust gas is recirculated. charger with wastegate or variable-turbine Sometimes referred to as EGR (exhaust-gas geometry) for exhaust-gas recirculation. precise monitoring and control of ex. and intercooler.. more ex. Yet another alternative is the use of an ad- In its neutral setting. (commercial vehicles). i. there is always a certain duced on cars in the 1970s. influence mercial vehicles. ated by the exhaust stroke of a cylinder. cylinder charge reduces its oxygen content bocharger must be suitably modified or a (the excess-air factor λ diminishes). controlled on the basis of differential air The EGR valve is controlled by the engine con. At low loads. The recirculation rates can hicle is lower than the turbocharger pressure components do. at high loads cylinder charge that are inert. mass using an air-mass flow meter (cars). For this reason. HC and soot) which opens whenever the pressure in the ex- increase. (internal exhaust-gas recirculation). the tur. This will require its use across virtu- greater thermal capacity (specific heat) of ally the entire operating range. there is always a pressure and returned (via a recirculated-exhaust-gas differential between exhaust-gas back pres- cooler if required) to the intake side of the sure and turbocharger pressure (turbo- engine (external exhaust-gas recirculation). justable venturi tube (lower pressure at the necting the exhaust-gas system upstream of constriction point) in the bypass to the air the turbocharger turbine to the intake system intake. Exhaust-gas recirculation is controlled by the exhaust-gas recirculation valve (EGR valve). The means of a valve. . If too VTG turbocharger that can generate the re- much exhaust gas is fed back into the cylinder. In accordance with statutory requirements. exhaust-gas recirculation on cars haust gas can be diverted from the exhaust is used only within the lower speed/power system by an exhaust-gas recirculation valve band. trol unit in response to engine speed and load. this process is a useful exhaust gas can therefore be recirculated by method for reducing NOx emissions.. In addition. exhaust recirculates. For diesel fuel. thus: of fuel injected relative to engine load. and observed. therefore. 1 start of injection Special engines with injection characteristics (injection dura- glass inserts and mirrors tion and rate-of-discharge curve) allow the fuel injection and combustion injection pressure processes to be injection direction. The quality and effectiveness of the 1) The stoichiometric ratio indicates the air mass in kg mixture formation is largely attributable to required to completely burn 1 kg of fuel (mL/mK). and the total amount bustion. torque (and therefore power output). exhaust-gas composition and combustion noise. all of these variable factors must be carefully balanced. on an engine’s specific fuel consumption. some amount required and therefore the mixture of which are in conflict with one another. As a variety of λ < 1: The intake air mass is less than the factors have to be taken into account. engine power output. λ < 1: The intake air mass is greater than the The composition and conditioning of the amount required and therefore the mixture air/fuel mixture has a fundamental effect is lean. ratio. Robert Bosch GmbH 50 Basic principles of diesel fuel injection Mixture Basic principles of diesel fuel injection The combustion processes that take place Mixture distribution inside a diesel engine are essentially dependent on the way in which the fuel is injected Excess-air factor λ into the combustion chamber. final design can only ever be a compromise. λ = 1: The intake air mass is equal to the air mass theoretically required to burn all of the The design of the fuel-injection system must fuel injected. 1 Progress of combustion in a direct-injection test engine with a multihole nozzle bustion inside the combustion chamber and. the mass of the fuel injected relative to required air mass for stoichiometric com- to crankshaft rotation. It indicates the ratio of intake air mass nition.5. be precisely matched to the engine concerned and its application. to indicate the degree to which the actual ration of injection. air/fuel mixture achieved in reality diverges tion and the distribution of the fuel inside from the theoretical (stoichiometric 1)) mass the combustion chamber. 14. the number of injection jets c d The times are measured The injection mass and the engine speed are from the start of sponta- operating parameters that determine the neous combustion. The excess-air factor λ was devised in order portant criteria are the timing and the du. this is approx. the is rich. A number of fuel-injection variables affect mixture formation and the course of com. the fuel-injection system. The most im. They are: Fig. the timing of ig. the engine’s emission levels and a b power output/efficiency. the degree of atomiza. æ SMK1865Y a 200 µs b 400 µs c 522 µs d 1. In Air mass order that a diesel engine and its fuel-injec.200 µs . λ= Fuel mass · Stoichiometric ratio tion system function properly. Robert Bosch GmbH Basic principles of diesel fuel injection Mixture 51 Lambda levels in diesel engines reveals that around the outer zone of the Rich areas of mixture are responsible for sooty droplet (vapor envelope). 3 3 0. The effect of this conditions. the aim is to obtain as much power air charge prior to or during combustion. But injection starts (ignition lag).e. those figures rise to λ >10. achieve that aim. high levels of excess air and The lambda levels for turbocharged diesel “moderate” motion of the air charge produce engines at full load are between λ = 1. the countered in a diesel engine. spontaneous ignition and pol. the total masses of fuel and air in the cylin. jection pressures (the highest currently used lutant formation are determined essentially is over 2. Within the heterogeneous mixture en. mixture formation and auto-ignition. However..20 µm) 2 2 Liquid fuel Lean 1. From this. 2 Air-fuel ratio curve for a static fuel droplet 3 Air-fuel ratio patterns for a moving fuel droplet λ= Excess-air factor λ Pure air a b 1 1 Fig. bustible lambda levels of 0. With a view to reducing engine weight and neous mixing of the injected fuel with the cost.5 droplet Ignition limits Fig. in principle.g. the localized fuel volume delivered must be precisely pro- excess-air factors can cover the entire range portioned to match the available amount of from λ = 0 (pure fuel) in the eye of the jet air and the speed of the engine. at high al- outer extremities of the spray jet. Good atomization is achieved by high in- der. as possible from a given engine capacity. In order to prevent the forma. diesel ures 2 and 3). is that less soot and. 2 Flame d Droplet diameter edge zone (approx. it can be deduced engines – in contrast to gasoline engines – that good atomization (large numbers of very have to be run with an overall excess of air.. To Auto-ignition occurs a few degrees of crank.0. small air excesses increase emission levels.3. the engine “must” be run shaft rotation after the point at which fuel with a “small” air excess at high loads.. Closer ex. 2. less NOX is Those excess-air factor figures represent produced during combustion. tive velocity between the jet of fuel and the air in the cylinder which has the effect of Diesel engines operate with heterogeneous scattering the fuel jet.. com- combustion. i. localized. This results is a high rela- by localized lambda levels. Therefore.3 3 a Low relative velocity Rich d b High relative velocity æ UMK0849-1E 0 Distance r æ SMK1866Y 1 Flame zone 4 λ=0 Combustible zone 2 Vapor envelope 4 3 Fuel droplet Eye of jet (flame zone) 4 Air flow . small droplets). they have to be limited. When idling and under no-load combustible lambda levels.15 and large numbers of localized zones with lean λ = 2. close to the injector to λ = ∞ (pure air) at the Low atmospheric pressures (e.1. It is not possible to achieve completely homoge.000 bar). titudes) also require the fuel volume to be ad- amination of a single droplet of liquid fuel justed to the smaller amount of available air.5 occur (Fig- tion of too many rich areas of mixture. nitrogen oxides (NOX). αV 10° BTDC αN Fig. determines the (Figure 2). fuel consumption and combustion noise. 2 HC jection for emissions 180 Emission Injection point BTDC at no load. nature of the air flow inside the combustion chamber. 140 tions αV Optimum start of injection for emissions 100 2 at full load. The characteristic operat- The point at which injection of fuel starts is ing data of each engine is thus determined the position stated in degrees of crankshaft and stored electronically in the form of an rotation relative to crankshaft top dead engine data map. Consequently. the degree of mixing of air and fuel is also dependent on start of Start of injection injection. injection tim. Thus. start of injection affects The point at which injection of fuel into the emissions such as soot. 1 Example of an 220 6 application: αN Optimum start of in. 2 Advanced Retarded 1 Cold start (< 0 °C) Start of injection 200 1. and the density and temperature 1 Distribution patterns for NOX and HC emissions 2 Start of injection versus engine speed and load plotted against start of injection for a commercial for a car engine started from cold and at normal vehicle without exhaust-gas recirculation operating temperature (example) % Crank- shaft ° 260 Up to approx. engine load. a product of incom- combustion chamber starts has a decisive plete combustion. and therefore on monoxide (CO). effect on the point at which combustion of unburned hydrocarbons (HC) and carbon the air/fuel mixture starts. speed and temperature. This fact performance characteristics. It also takes account of fuel-consumption consider- The position of the piston relative to top ations. The start of injection requirements differ ac- ing plays a major role in optimizing engine cording to engine load (Figure 1). demands load-dependent adjustment of the start of injection. pollutant-emission requirements and dead center at that moment (as well as the noise levels at any given power output shape of the intake port). The engine data map plots center (TDC) at which the nozzle opens and the required start of injection points against fuel starts to enter the combustion chamber. emission levels. Accordingly. 60 TDC tions 4 3 2 1 1 2 3 4 5 6 0 æ UMK0796-2E æ UMK0797-1E Fig.000 rpm 2 Full load Engine speed 3 Medium load . Robert Bosch GmbH 52 Basic principles of diesel fuel injection Start of injection and delivery Start of injection and delivery of the air. as HC emissions are lower under those condi. as NOX 4 emissions are lower NOX 1 3 under those condi. This is pos. An advanced start of injection increases the temperature in the combustion cham... sible because there is a definite relationship to start of injection crease in compression pressure also makes between the start of delivery and the start of combustion much noisier.. The start-of-injection map (without exhaust-gas recirculation): (Figure 2) shows the inter relationship be- No load: 4. of fuel delivery creases its fuel consumption. a different start of Full load: 6. It relates to the point at which the fuel injection pump starts to deliver fuel to the Advanced start of injection injector. the NOX emission levels rise travel from the high-pressure pump to the while HC emissions are lower (Figure 1).. very tight tolerances when modifying the the start of injection points are as follows: start of injection to suit a particular engine. higher speeds 2). The steep in. If combustion is initiated the start of delivery is easier to determine a long way before TDC. The duration of combustion at livery is another aspect that is often consid- full load is 40. load and speed for a car engine...12° crankshaft before TDC tween the start of injection and engine tem- Full load: 3. As a result. (particularly in the case of in-line and dis- The heat lost in the process diminishes the tributor injection pumps) is performed on 1) Time from start efficiency of the engine and therefore in. the start of injection Start of delivery for car and commercial-vehicle engines is In addition to start of injection. ered. nozzle depends on the length of the pipe and produces an injection lag stated in degrees of 2) Time from start of Retarded start of injection crankshaft rotation that varies according to injection to start of A retarded start of injection under no-load engine speed. ignition conditions can result in incomplete combus. the combustion than the actual injection point. compensated for – which is the reason why a tion takes place at a time when the tempera. the optimum specific fuel consumption and hydrocarbon points of combustion start for low fuel con. . start of de- 3. Robert Bosch GmbH Basic principles of diesel fuel injection Start of injection and delivery 53 Guide figures (EURO III) The partially conflicting interdependence of On a diesel engine’s data map.. Since. demand a trade-off combined with on the statutory exhaust-gas emission limits.60 ° of crankshaft rotation. Direct-injection car engines: Minimizing blue and white smoke levels No load: 2 ° crankshaft before TDC to requires advanced start of injection and/or 4 ° crankshaft after TDC pre-injection when the engine is cold. on older fuel-injection sys- The highest final compression temperature tems and when the engine is not running..10 ° earlier. nition lag (in terms of crankshaft rotation) at tion and therefore in the emission of un. 2° crankshaft after TDC When the engine is cold. On that basis and based other. The engine also has a longer ig. load and temperature. the basis of the start of delivery. synchroniza- pressure rises steeply and acts as a retarding tion of the start of injection with the engine force against the movement of the piston.. and soot sumption are in the range of 0. Part load: 6° crankshaft before TDC to In order to keep noise and pollutant emis- 4 ° crankshaft after TDC sions at acceptable levels. fuel-injection system must be able to adjust ture in the combustion chamber is dropping the start of delivery/start of injection in re- (Figure 1).15° crankshaft before TDC injection is frequently necessary when the engine is running at part load than when it is Direct-injection commercial-vehicle engines at full power. emission levels on the one hand. Both these effects must be burned hydrocarbons (HC) since combus.8 ° crank. is reached at TDC. sponse to engine speed... (black smoke) and NOX emissions on the shaft before TDC.. injection (injection lag 1)).6° crankshaft before TDC to perature. The time it takes for the pressure wave to ber. the BTDC BTDC injection duration is 10 15 20 25 30 35 ° 10 15 20 25 30 35 ° varied by variation of Duration Duration the injection pressure. i. in mm3/stroke or tion control system.0 40 ° .0 engine with common. 1 Specific fuel consumption be in g/kWh versus 2 Specific nitrogen oxide (NOX) emission in g/kWh start of injection and injection duration versus start of injection and injection duration Cranksh.0 Six-cylinder diesel commercial-vehicle -5 210 -5 5. gine’s power output at a constant level of efficiency (η 1/be) is directly proportional to the injected fuel quantity.5 Figures 1 to 4 Start of injection Start of injection Engine: 0 225 0 3. systems controlled by an electronic gover- nor. the diesel fuel is com- z is the number of cylinders in the engine pressible.400 rpm. Fuel density.0 ° æ SMK1868E æ SMK1867E In this example.0 20 7 30 50% power -20 0 -20 .° ATDC ATDC 300 10 10 2. ° Cranksh.000 QH = [mm3/stroke] lead to fluctuations in the level of pollutant 30 · n · z · emissions and in the engine’s power output.0 15 Operating conditions: -15 -15 . the required injected fuel quantity can It is evident from this equation that the en. it is. mm3/injection cycle is then: Variations in the injected-fuel quantity P · be · 1. be delivered with a high degree of accuracy. . compressed. ables: gine cylinder per power stroke is calculated the fuel-metering cross-section of the using the following equation: nozzle the injection duration P · be · 33. me. the density of the fuel tion in g/kWh n is the engine speed in rpm and At high pressures.e. in fact. and be is the engine’s specific fuel consump.2 275 5 250 5 2. 19 . . Robert Bosch GmbH 54 Basic principles of diesel fuel injection Injected-fuel quantity Injected-fuel quantity The mass of fuel injected by the fuel-injection system depends on the following vari- The required fuel mass.0 rail fuel injection -10 200 -10 10 197 . in mg/mm3 is temperature. in mg for an en.33 me = [mg/stroke] the variation over time of the pressure n·z difference between the injection pressure where and the pressure in the combustion cham- P is the engine’s power output in kW ber. 7.0 20 n = 1. By the use of high-precision fuel-injection dependent. This affects the injected fuel quantity and must The corresponding fuel volume (injected therefore be taken into account by the injec- fuel quantity). QH. direct-injection commercial-vehicle ble to suit the demands of all engine oper. The injection must be reliably terminated. the following demands onds.40 ° It should be possible to vary the injec.0 01 -20 -20 æ SMK1869E 0.1 00 10 0. or in millisec- tions. ° ATDC ATDC 1. rotation.00 10 10 0.40 Start of injection Start of injection 0 0 0 0. ating conditions (e.36 ° of crankshaft rotation.20 0..000 rpm. engines: 25.20 5 5 0 0.. (approximate figures at rated power): tial effect on fuel consumption.08 0. illustrated by the following examples Even small discrepancies have a substan.08 ° æ SMK1870E ° BTDC BTDC 10 15 20 25 30 35 ° 10 15 20 25 30 35 ° Injection duration Injection duration . shaft or camshaft rotation.30 0. that is equal 1) Equal to half the The term “injection characteristics” refers to an injection duration of 1. emission direct-injection car engines: 32. speed).0 0. and tion pressure as independently as possi.0 9 0. This refers 3 Specific emission of unburned hydrocarbons (HC) in 4 Specific soot emission in g/kWh versus start g/kWh versus start of injection and injection duration of injection and injection duration Cranksh.38 ° of levels and combustion noise (Figures 1 crankshaft rotation to 4). load.0 -15 50 -15 0. It is specified in degrees of crank- characteristics are very important considera. In terms of time at an injection pump speed 1) of 2..1 0. 15 10 0 0. Different diesel combustion processes are placed on the fuel-injection system: demand different injection durations as Fuel injection must be precisely timed... For that reason. Robert Bosch GmbH Basic principles of diesel fuel injection Injection characteristics 55 Injection characteristics to the period of time that the nozzle is open and allows fuel to flow into the combustion An engine’s emission and fuel-consumption chamber.25 ms. of crankshaft rotation. indirect-injection car engines: 35.50 0.. An injection duration of 30° of crankshaft Uncontrolled “post-injection” rotation corresponds to 15° of camshaft leads to higher emission levels. One of the main parameters of the injection pattern is the injection duration.g. the injection duration of time. engine speed on to the pattern of the fuel quantity injected In order to minimize fuel consumption four-stroke engines into the combustion chamber as a function and soot emission.09 0 -5 -5 0. ° Cranksh. -10 -10 0. must be defined on the basis of the engine operating conditions and the start of injec- Injection duration tion (Figures 1 and 4). or post-injec- phase Two-stage pressure gradient (4) during the tion (Figure 5. BTDC) æ UMK1721-3E combustion for Crankshaft ° pre-injection phase TDC ZV Ignition lag for main Crankshaft angle of rotation injection phase without pre-injection . slightly less steep with ZV* *ZV: w/o PI: 4…10° cranksh. or injection pump in conventional systems. espe. injection pumps.) regeneration of a particulate filter (Figure 6) 5 Gradual pressure gradient (conventional fuel injection) 5 Injection patterns 6 Gradual pressure drop (in-line and distributor injection pumps) v b (up to 40…60° cranksh. Robert Bosch GmbH 56 Basic principles of diesel fuel injection Injection characteristics Fig. tub needle lift curve [but not pressure Retarded post-injection (9) of fuel as a This has the following consequences for the gradient]. common rail) 5…15° cranksh. pre-injection is currently controlled 4 Two-stage pressure injection phase (3. 7) in order to reduce by hydromechanical means. the speed of the pump has delivery point is signifi. of injection close to TDC engine is intended. out exhaust-gas recirculation ble (1). Cars with PI: 1… 2° cranksh. On unit injector systems (UIS) for rail system) Constant high pressure during the main cars. v Duration of cars up to 15° cranksh. BTDC …5° cranksh. combustion for main injection phase Start of MI (comm. the following injection the pressure is generated continuously at maximum load (engines without exhaust-gas functions are required (Figure 5): throughout the injection cycle by an injec- recirculation). 5 Adjustments aimed at low Injection pattern Conventional injection pattern NOX levels require starts Depending on the type of use for which the With conventional fuel-injection systems. i. a direct effect on the fuel delivery rate and cantly in advance of the cially on DI engines consequently on injection pressure. The fuel Pre-injection (1) in order to reduce com. 2 Main injection (MI) main injection phase in order to reduce With solenoid-valve controlled distributor phase 3 Steep pressure NOX and soot emissions on engines with.) 7 Steep pressure drop ps (UIS. Post-injection immediately following the injected fuel quantity are interdependent by holder assemblies main injection phase (8) in order to virtue of the link between the cam and the can produce a bath. start of injection and is Positive pressure gradient during the main In the case of port-controlled distributor dependent on the injection system injection phase (3) in order to reduce and in-line injection pumps. UPS. Items 5 and 6). tion pump. the injection NOX emissions on engines without pattern consists exclusively of a main injec- 1 Pre-injection (PI) exhaust-gas recirculation tion phase. 8 Advanced Comm. ATDC. reduce soot emissions. vehs at high loads 5° cranksh. 1…5° 9 Retarded post-injection 1 9 ps Peak pressure po Injector opening po pressure b Duration of 2 (up to 36°) 90…180° cranksh. without pre. Thus.e. injection characteristics: duces combustion type catalytic converter and/or in order Injection pressure increases with engine noise but not always to raise the exhaust-gas temperature for speed and injected fuel quantity soot emission levels. bustion noise and NOX emissions. This re. vehs 3 4 5 6 7 8 Injection pressure pe post-injection (PO) 6…12° cranksh. gradient (UPS with CCRS two-stage soot emissions on engines with exhaust- solenoid valve) gas recirculation Pressure generation and delivery of the (dual-spring nozzle. pre-injection is also possi- gradient (common. reducing agent for an NOX accumulator. The gradient then rises steeply from the start of combustion. Peak pressure is also a measure of the quality of fuel atomization in the Injection pressure pe combustion chamber. This has the following effects: The ignition lag of the main-injection The consequences of this are the following: phase is shortened. The pattern of combustion is af- æ UMK1587-6E fected in such a way that combustion noise.. Depending on the timing of the main injec- bustion in an engine without exhaust-gas tion phase and the gap between the pre- recirculation (shallow pressure gradient injection and main-injection phases. 7 ignition lag of the main injection quantity is b h MI a Without pre-injection h PI stroke h a. Injection volume m e speeds This produces a gradual increase in pressure 3 Low engine speeds and consequently. 7 Effect of pre-injection on combustion-pressure pattern Pre-injection The pressure curve of an engine without pre- injection (Figure 7a) shows only a shallow Combustion pressure pz gradient leading up to TDC in keeping with the compression. 6 fuel and determine the shape of the injection 1 High engine speeds pattern. The determining factor for the stresses to 6 Injection-pressure curve for conventional fuel injection which the components of an injection pump and its drive system are subjected is peak pressure. and steep (Figure 7b). Pre-injection involves the injection of a jection but drops again before the end of small quantity of fuel (1.b b With pre-injection very short. the and therefore quiet combustion). TDC hPI Needle lift during fuel consumption and – depending on the pre-injection Crankshaft angle of rotation type of combustion – NOX and HC emis. and Small injected fuel quantities are injected The combustion pressure gradient is less at low pressures. 1 On indirect-injection engines (precombustion 2 or swirl-chamber engines)..4 mm3) in ad- the injection period (as from the end of vance of the main injection phase in order the fuel-delivery period) down to the to “precondition” the combustion chamber. Pre-injection enables a less abrupt rise in Valve needle combustion pressure to be achieved. The Fig. injector closing pressure. hMI Needle lift during sions are reduced. “quiet combustion”. main injection . as is required for good com. specific fuel consumption will vary. That b rapid rise in pressure is the cause of the nois- a ier combustion encountered on diesel engines without pre-injection. throttling-pintle 3 nozzles are used which produce a single jet of æ UMK1722-1E Fig. The injection pattern is approximately triangular. This type of nozzle controls the outlet 2 Medium engine cross-section as a function of the needle lift. Robert Bosch GmbH Basic principles of diesel fuel injection Injection characteristics 57 Injection pressure rises at the start of in. Rapidly closing noz- In contrast with the pre-injection and zles with a sufficiently high closing pressure main-injection phases. nent similarly increases the level of un- Another means of reducing NOX emissions burned hydrocarbons in the exhaust gas is the NOX accumulator-type catalytic convert. Retarded post-injection can lead to thinning 8 Effect of injector design on hydrocarbon emissions of the engine oil by the diesel fuel. 0 æ UMK0800-1E 0 1 2 3 mm3 duced by 20. It introduces a precisely mea. Post-injection occurs when of delivering a measured amount of reducing the nozzle momentarily re-opens after closing agent for a particular type of NOX catalytic and allows “poorly conditioned” fuel to escape converter. jection orifices are drilled into the needle- seal seats have the smallest dead volume. (Figure 8). In this case. The effect to post-injection. This fuel is not completely or exhaust stroke at a point up to 200° crank. That dead volume fuel in the exhaust gas acts as a reducing runs into the cylinder after the combustion agent for nitrogen oxides in suitable NOX process has finished and also partially es- catalytic converters. It is therefore essential that the injection system is designed in consultation with the engine g/kWh manufacturer. The resulting mixture of fuel and exhaust gas is expelled Fuel retained in the nozzle on the cylinder through the exhaust ports into the exhaust. Sac-less nozzles in which the in- er (see chapter “Emission control systems”). Robert Bosch GmbH 58 Basic principles of diesel fuel injection Injection characteristics Post-injection Post-injection and dead volumes Retarded post-injection Unintended post-injection has a particularly Post-injection can be employed as a means undesirable effect. As a result.. burned. Retarded post-injection can also be used to raise the exhaust temperature in an oxidation-type catalytic converter in order to assist regeneration on the part of a particulate filter. 1 Engine with Injection and blind hole 1 l/cylinder Camshaft-driven injection systems that volume of injector 2 Engine with are capable of post-injection are also under 2 l/cylinder development. soot particles are micro-blind hole re-burned and soot emissions can be re. side of the needle-seal seats has a similar gas system during the exhaust stroke. with the shaft after TDC. 8 of any post-injection for an NOX catalytic a Injector without converter or particulate filter. heat of the exhaust gas.70 %. or may not be burned at all. 2 1 2 Advanced post-injection HC emission The common-rail fuel-injection system can perform post-injection immediately following the main-injection phase independently 1 Fig. In that way.. . This fuel compo- emission levels are moderately reduced. b blind hole the fuel is injected while combustion is still a b Injector with in progress. The post-injection phase follows into the cylinder at a late stage in the combus- the main-injection phase during the ignition tion process. the NOX capes into the exhaust gas. unburned hydrocarbons. the fuel injected is and a low static pressure in the supply line can not burned but is merely vaporized by the prevent this undesirable effect. result that it is released into the exhaust gas as sured amount of fuel into the exhaust gas. Robert Bosch GmbH Basic principles of diesel fuel injection Injection characteristics 59 Timing characteristics of 9 Chain of interaction from cam pitch to injection fuel-injection systems pattern plotted against camshaft angle Taking as its example a radial-piston distributor injection pump (VP 44). 0 without pre-injection trol for the benefit of the engine. 1.000 bar unit pumps) the characteristics are similar. unit injectors and 2. It shows that 3 the pressure and injection patterns vary 2 Cam pitch greatly between the pump and the nozzle Rate of lift vH and are determined by the characteristics of 1 the components that control injection (cam. As 400 a result.4 system must be precisely matched to the hM engine. compression losses occur and a fuel 0 injection lag is produced. mm m/s trates how the cam on the cam ring initiates 4 hN delivery of fuel by the pump and the fuel ultimately exits from the nozzle. high-pressure valve. The fuel volume mm inside the pipes is compressed by the dy.600 The common-rail system on the other hand 1.200 pLD Line pressure pressure fuel lines and the nozzle. 800 nozzle side Every time fuel is injected. stroke In all fuel-injection systems in which 0 the pressure is generated by a pump piston (in-line injection pumps. 1. 0.000 bar the fuel-injection system for an individual 1. in pipe . -24° -16° -8° TDC 8° 16° mental volume must be equal for all cylin. 0 The greater the detrimental volume.600 nozzle. A major consideration 4 when developing a fuel-injection system is therefore to keep the detrimental volume as Fig. Figure 9 illus.25 Needle lift namic processes generated by the pressure hD wave. the high. fuel line and mm Solenoid-valve nozzle). ° injection system.200 behaves entirely differently. 9 Injection rate Q small as possible. Camshaft angle tL Fuel transit time ders. æ UMK0798-1E pump (VP 44) at full load In order to guarantee consistency of con. the detri. the fuel-injection 0. the detrimental volume is pressurized and depressurized. Line pressure 800 pLP pump side Detrimental volume in conventional 400 injection systems The term “detrimental volume” refers to the 0 volume of fuel in the high-pressure side of 2. the mm 3 poorer the hydraulic efficiency of the fuel. This is made up of the high-pressure tL side of the fuel-injection pump. The unit injector system 2 Example of radial-piston distributor injection has the smallest detrimental volume. For that reason. 0 pump. 11 pe = 800 bar Direct-injection engine. Robert Bosch GmbH 60 Basic principles of diesel fuel injection Injection characteristics. 10 Injection pattern of common-rail injection system 11 Effect of injection pressure on black-smoke emission and fuel consumption SZB +1° pe = 435 bar αS Black smoke Pre-injection 2 + 4° Fig. Multiple pre.2 bar 200 435 bar – 8° 190 pe Injection pressure 2 4 6 8 g/kWh αS Start of injection Time t Nitrogen oxides NOX after TDC . A high fuel- ally constant for the entire injection cycle system pressure results in a high rate of fuel (Figure 10). 10 Main injection 1 Injection pressure p pr Fuel-rail pressure –12° po Nozzle-opening 800 bar pr –8° pressure 0 g/kWh αS Fuel consumption be 220 +1° + 4° Fig. The degree of swirl increases as are controlled by the crankshaft-position/ the piston approaches TDC. Since the control unit controls the in. and the higher tors. 210 engine speed 1. all engine operating points and optimized to This effect is assisted by the movement of the engine's operating requirements.and post-injection pressure at the nozzle can be higher than in phases are possible. swirl effect).200 rpm. the time that the injector valve is open and en. Thus. speed of movement of the air inside the tirely independent of the engine or pump combustion chamber is relatively slow as it speed (time-based injection system). the higher the relative Short pipes join the fuel rail to the injec. po –12° æ UMK0801-1E æ UMK1585-3E mean pressure 16. Because of the almost uniform outflow at the nozzle. the high-pressure pump caused by the collision of the turbulent jet can be significantly smaller and designed of fuel with the air inside the combustion for a lower peak drive torque. For a given system pressure. time-based system of the electronic diesel control (EDC) system. Fuel atomization is delivery pattern. Therefore. Injection pressure Injection characteristics of Injection pressure common-rail system A high-pressure pump generates the fuel. the more finely the jectors. start of injection. The fuel-rail pressure remains virtu. velocity between fuel and air. By clever dimensioning tion are infinitely variable in engine applica. They the piston. the density of the air. the injected fuel Direct-injection (DI) engines quantity is proportional to the length of In diesel engines with direct injection. chamber. of fuel through the injector jets. fuel is atomized.e. the fuel-injection pump. the injection tions. only moves as a result of its mass inertia (i. duration and the air “attempts” to maintain the velocity pressure can be individually regulated to suit at which it enters the cylinder. start of injection and end of injec. The process of fuel injection uses the pres- rail pressure independently of the injection sure in the fuel system to induce the flow cycle. of the high-pressure fuel line. in which rising swirl chamber in such a way that the glow combustion pressure propels the air/fuel plug is just within the injection jet. Number and alignment of injector jets 61 In a direct-injection engine. Injection pressures as high as 2.1. The in- mixture out of the swirl/precombustion jection direction is matched precisely to the chamber. Robert Bosch GmbH Basic principles of diesel fuel injection Injection pressure. have hole-type nozzles with between 4 and sures of 1. see chapter “Nozzles”) However.050 bar for car engines and 10 injection orifices (most commonly 6. the consumption.. injection orifices. target figures at maximum torque for cars and commercial vehicles are in the range Indirect-injection engines 800. No post-injection – – (Soot h) – – – – low-emission and economical diesel- Incorrect injection pattern () () – engine operation.1. a good the combustion chamber. .. 1 Effect of most important injection parameters Effect engine damage NOX emissions Loss of engine consumption HC and soot Poor engine Higher fuel emissions Increased Increased response Possible Uneven running power Problem Injection too early () () – Table 1 This table illustrates Injection too late – how greatly fuel-injection Injection pressure too low – – parameters affect engine Dirt in nozzle – – characteristics. The nozzle Indirect-injection (IDI) engines injects the fuel into the precombustion or Indirect-injection engines.2. Overall..000. Only a (poor dispersal and insufficient fuel well matched and injected) precisely functioning fuel-injection system No pre-injection – – (HC h) – – can guarantee quiet.. in black smoke and hydrocarbon emissions.8 1.000. Modern direct-injec. Inaccuracies in injec- swirl/precombustion chamber and in the tion direction result in poorer utilization of channel connecting it to the main combus. Indirect-injection engines use pintle nozzles with only a single injection jet. no ad. combustion air and therefore to an increase tion chamber..800 bar for commercial vehicles... Divergences of the torque curve combined with low smoke order of only 2 degrees from the optimum emission demands a high injection pressure injection direction lead to a detectable in- when the engine is under maximum load at crease in black-smoke emission and fuel low speeds.000 bar number of injection jets enable smoke and particulate emissions to be Direct-injection engines substantially reduced. In this type of engine. have high rates of air flow in the combustion chamber.. vantage is gained by increasing injection pressure above about 450 bar. fuel is injected Injection direction and into the combustion chamber at high pressure.400 bar. Based on those conditions. Diesel engines with direct injection generally tion systems now generate full-load peak pres. peak pressure is available only arranged as centrally as possible. The injec- at the higher engine speeds (except with tion direction is very precisely matched to the common-rail system). for example Basically. All new diesel-injection systems for cars 160 kW/cylinder) and commercial vehicles are electronically as engines for railway locomotives and controlled. 1 Applications for Bosch diesel fuel-injection systems M M M A/P P/H ZWM ZWM MW MW MW MW CW CW PF PF PF PF PF PF Fig. fuel-injection systems have experi. P. Electronic Diesel Control (EDC) systems. ZWM. Mechanical control of diesel fuel-injection 80 kW/cylinder) systems is being increasingly displaced by to drive fixed installations such as emer. design for many different purposes (Figure 1 and Table 1). as engines for heavy trucks. Robert Bosch GmbH 62 Overview of diesel fuel-injection systems Requirements Overview of diesel fuel-injection systems Diesel engines are characterized by high fuel Requirements economy. H. 10 kW/cylinder) in such a way that it mixes effectively with the as fast-running engines for cars and air in the cylinder as demanded by the type of light commercial vehicles (up to approx. ships (up to 1000 kW/cylinder). Since the first volume-production fuel-injection pump was introduced by Bosch Ever stricter statutory regulations on noise in 1927. more economical fuel consumption continually place greater demands on the fuel-in- Diesel engines are used in a wide variety of jection system of a diesel engine. CW In-line fuel-injection VR VR VR VR VR pumps of increasing size PF Discrete fuel. 1 M. UIS UIS UIS UIS UIS injection pumps VE Axial-piston pumps UPS UPS UPS UPS VR Radial-piston PF(R) PF(R) æ UMK1563-1Y pumps UPS Unit pump system CR CR CR CR CR CR UIS Unit injector system CR Common-rail system . omnibuses and tractor vehicles (up to approx. the fuel-injection system is required to inject a precisely metered amount of fuel at to drive mobile power generators high pressure into the combustion chamber (up to approx. and exhaust-gas emissions and the desire for enced a process of continual advancement. means of the injected fuel volume as it has no 50 kW/cylinder) air intake throttle. The power output as engines for construction-industry and and speed of a diesel engine is controlled by agricultural machinery (up to approx. engine (direct or indirect-injection) and its 50 kW/cylinder) present operating status. gency power generators (up to approx. MW. VE VE VE VE VE VE A. .250 – em7) DI 3 ..200 – m. O 125 800 – m DI 4. PO6) Mv DI 6 .... 6 4. Robert Bosch GmbH Overview of diesel fuel-injection systems Requirements 63 1 Properties and characteristic data of the most important fuel-injection systems for diesel engines Control Fuel-injection system Type of use Injection parameters Engine-related data method O Off-road vehicles 1) Max.400 75 ATDC 6) PI up to 30° BTDC..800 25 UIS 30 N 160 1.600 PI..800 – Mv DI 82) 2.200 – m. 12 2.. 8 2...300 45 2a) EDC 16 and above: Discrete/cylinder-pump systems 6 cylinders 3) PI up to 90° BTDC.000 20 A O 120 750 – m DI/IDI 2 . construction VP37 (VE.. 12 2.400 25 and agricultural VP37 (VE. h DI/IDI 4 . 6 3.MV) O 125 800 PI Mv7) DI 4.350 – em DI 5 .600 30 cylinders are also Radial-piston pumps possible with two VP44 (VR) P 85 1.. em DI/IDI Any 4. 8 5.500 25 2) Larger numbers of VP30 (VE.300 – m.600 45 P7100 N. 12 2..600 – Mv DI 82) 2.EDC) O 125 800 – em7) DI 4... em DI/IDI Any 300 .. 6 4.. rated speed Max. 6 5.. O 900 950 – m.400 PI Mv7) DI 4 . permissible IDI Indirect injection Injected volume DI Direct injection Solenoid valve pressure at jet injection cycle PO Post-injection PI Pre-injection S Ships/trains per cylinder Mechanical per stroke/ Number of Hydraulic P Cars and cylinders Type h m em Mv bar mm3 (0..600 – Mv DI 82) 2. 8 2. O. 12 2. 10 1.800 – Mv DI 82) 3.500 – Mv7) DI 4... O 250 950 – m. 75 . PO5) Mv DI 3 ..500 55 H1 N 240 1.150 30 PO possible 4) Up to 5500 rpm PF(R)… large-scale P. 8 2.. diesel 18. 12 2. O 250 1.EDC) P 70 1.000 1. 6 2. em.. h DI/IDI 6 . N.8004) 30 8) This type of pump CR 2nd generation P 100 1.800 30 gines.600 – Mv DI 82) 4. 120 1. 6 4.800 27 MW8) P.. em DI 4 . 12 2.500 1. em DI 4 .400 25 1) Fixed-installation en- VE.000 when overrunning 5) PI up to 90° BTDC... h DI/IDI 6 ... – m. 12 2. 6 3.050 PI Mv DI 52. UIS 32 N 400 1. O 1... 6 4.000 80 UPS (PF.. em.350 PI. UIS P1 P 60 2.. em DI 4 . em. S 400 1. power output Electromechanical light commercials N Trucks and buses Max. h DI/IDI 6 ..500 25 control units VP44 (VR) N 175 1.000 1..500 2.1 MPa) rpm kW In-line injection pumps M P..300 – em DI 6 . 16 2... em.300 – m.800 200 Axial-piston pumps VE....400 55 H1000 N 250 1.200 1.250 – m DI 4 . 6 4.F N. O 800 1.MV) P 70 1.. N.. O 250 1..400 PI. O 1. 800 ..400 35 PO possible 7) Electrohydraulic UPS 20 N 250 1.500 55 P8500 N. 6 3. O 60 550 – m.400 80 UPS 12 N 180 1. PF(R)… O 13 .F P 70 350 – m IDI 3 .000 450 injection timing adjustment using Common-rail injection systems solenoid valve CR 1st generation P 100 1...000 4 .200 – m.000 1. em DI 6 ..000 35 PO up to 210° UIS 31 N 300 1.400 160 P9 S..200 70 P10 S... O 150 1. em IDI 4 . O 250 1..000 180 CW S..600 36 P3000 N.900 PI Mv7) DI 4. PO3) Mv DI 3 .MV) S 3.....600 – Mv DI 6 .000 – m.500 55 P8000 N.100 – m DI 4 . – m.800 200 with new systems .800 25 Table 1 VE..800 30 machinery VP30 (VE. 2a) 4..200 30 is no longer used CR N....F P 70 1. 12 2..400 140 ZW (M) S. 450 .. 8 4. S 150 . 20 1. The the fuel pressure. to move upwards. Robert Bosch GmbH 64 Overview of diesel fuel-injection systems Designs Designs running control. system is the method by which they generate The stroke of the plunger is invariable. the nozzle opens and fuel is in- Electronic control concepts enable systems jected into the combustion chamber. the inlet port. fuel can escape and pressure is Fig. generally arranged in-line (hence the name tween the different types of fuel-injection in-line fuel-injection pump). active surge damping. the camshaft (7) integrated in the injection nally controlled – at a specific opening pres.g. generation phase. pump and driven by the engine. All components must be precisely the start of delivery. and is re- sure that is set to suit the engine and the turned to its starting position by the plunger fuel-injection system. The nozzle opens – if it is not exter. The essential difference be. It closes when the fuel spring (5). to perform a variety of supplementary func. The pump plunger is moved in the bustion chamber. When the helix (3) of the plunger clears. In-line fuel-injection pumps (Figure 1) have a separate pump unit consisting of a cylinder The nozzle projects into either the swirl/ (1) and plunger (4) for each cylinder of the precombustion chamber or the main com. in the Standard in-line fuel-injection pumps precise quantity required. The fuel pressure therefore increases. The plunger continues matched to one another. The individual pump units are pressure drops. cruise control and boost- pressure control). stroke marks the beginning of the pressure precision tolerances from high-strength ma. depending on the type of delivery direction (in this case upwards) by engine. 1 a Type PE standard 1 Method of operation of an in-line fuel-injection pump in-line fuel-injection pump b In-line control-sleeve a 10 b 10 fuel-injection pump 1 1 2 1 Pump cylinder 9 2 2 Inlet port X 3 Helix X 3 4 Pump plunger 3 5 Plunger spring 4 8 6 Adjustment range 4 using control rod 5 5 (injected-fuel 6 6 quantity) 7 Camshaft 8 Control sleeve 9 Adjustment range using actuator shaft æ UMK1759Y (start of delivery) 7 7 10 Fuel outflow to nozzle X Effective stroke . smooth. The function of a fuel-injection system for a diesel engine is to inject the fuel into the In-line fuel-injection pumps combustion chamber at high pressure. all closes off the inlet port (2) on its upward individual components are made to high. This point is referred to as terials. engine. point at which the top edge of the plunger Because of the high pressures involved. and at precisely (Type PE) the right moment. tions (e. Item 4). In the course of each rotation of pendent control in comparison with a Type the drive shaft. Distributor injection pumps have only one pump unit that serves all cylinders (Fig- Plunger travel between the points at which ures 2 and 3). is equal to the number of cylinders in the This changes the start of delivery. 2 1 Injection timing adjustment range on roller ring 2 Roller 6 3 Cam plate 4 Axial piston 5 Control sleeve 7 6 High-pressure chamber æ UMK1760Y 7 Fuel outflow to nozzle 1 X 8 8 Metering slot X Effective stroke lost. (Figure 3. A vane pump forces the fuel the inlet port is closed and opened into the high-pressure chamber (6). A rotating central effective stroke and therefore the injected. It allows plunger lift to port A rotating cam plate (Figure 2. The nozzle closes and fuel injection Distributor injection pumps ceases. High- is termed the effective stroke (X). engine. Item 4) or several radial means of a control rod (6). fers from a conventional type by virtue of a control sleeve (8) which slides over the Axial-piston distributor pumps pump plunger. The control rod is controlled slots (8) and spill ports. Item 5). They travel over rollers (2) on the roller ring and thus cause the distributor The control-sleeve in-line fuel-injection piston to describe a rotating as well as a lift- pump thus has an additional degree of inde. Control-sleeve in-line fuel-injection pump Item 5) or a high-pressure solenoid valve This type of in-line fuel-injection pump dif. Robert Bosch GmbH Overview of diesel fuel-injection systems Designs 65 2 Method of operation of port-controlled axial-piston distributor injection pump 2 3 4 5 Fig. Item 3) is closing – that is the distance travel by the driven by the engine. . pressure generation is performed by an axial The position of the helix can be altered by piston (Figure 2. gine (7). independently of engine speed. The number of cam plunger before it closes off the inlet port – to lobes on the underneath of the cam plate be altered by means of an actuator shaft (9). distributor piston opens and closes metering fuel quantity. The injection duration can be varied by means of a control sleeve (Figure 2. ing action. thereby distributing by a mechanical governor or an electrical the fuel to the individual cylinders of the en- actuator mechanism. the piston accordingly com- PE standard in-line fuel-injection pump – pletes a number of strokes equal to the it allows the start of injection to be varied number of engine cylinders to be supplied. This alters the pistons (Figure 3. They are also suitable for use (1). construction machinery and small- The cam ring is rotated by the timing device scale engines. with high-viscosity heavy oils. With this type of distributor injection nism. an electronically controlled high- effective stroke. On large-scale . They operate in the same way as Type PE in-line fuel-injection pumps. primarily on marine engines. locomotive engines. high-pressure is generated by control unit and engine control unit) gener- a radial-piston pump with a cam ring (Fig. the fuel es- capes so that no pressure build-up occurs Radial-piston distributor injection pump and therefore fuel injection is not possible. When it is open. But – in common with all discrete cylinder systems – discrete fuel-injection pumps do not have their own camshaft (externally driven). The cams which drive the discrete fuel-injection pumps are on the same camshaft that operates the engine valvegear. When the solenoid valve is closed. The timing device can vary the pump’s start pressure can build up in the high-pressure of delivery by turning the roller ring (1). ate the control and regulation signals. However. One or two electronic control units (pump piston pump. jected-fuel quantity and varies the start of injection. a control sleeve (5) determines the pump. they have to be capable of Type PF discrete injection pumps are used withstanding greater mechanical stresses. Robert Bosch GmbH 66 Overview of diesel fuel-injection systems Designs 3 Method of operation of solenoid-valve controlled radial-piston distributor injection pump 8 6 7 Fig. chamber (6). thereby controlling the pressure solenoid valve (5) meters the in- injected-fuel quantity. ure 3. Radial-piston pumps can generate Discrete cylinder systems higher injection pressures than axial-piston Type PF discrete injection pumps pumps. Instead of the cam plate used on the axial. With radial-piston distributor pumps. the start of injection and start of delivery are always controlled by solenoid valve. 3 1 Injection timing 2 adjustment range 4 on cam ring 2 Rollers 3 Cam ring 4 Radial piston 5 High-pressure 3 solenoid valve 6 High-pressure æ UMK1765Y 1 chamber 7 Fuel outflow to 5 injector 8 Metering slot In a Type VE port-controlled axial-piston Solenoid-valve controlled distributor distributor pump with mechanical governor injection pumps or electronically controlled actuator mecha. Item 3) and two to four radial pistons (4). holder assembly (2) and the fuel-injection pump are linked by a short high-pressure line Unit injector system (UIS) (3) specifically designed for the system com- In a unit injector system (UIS). There is a unit injector for each allows for more straightforward attachment cylinder fitted in the cylinder head. the fuel-in. however.050 bar) is possible than is As with the unit injector system. There is one unit pump assem- actuated either directly by a tappet or indi. It adjusts the injected-fuel by opening and closing the high-pressure quantity by means of a linkage integrated solenoid valve (3). in the engine. an ates on the same principle as the unit injector adjustable roller can be used to provide an system (Figure 5). a significantly higher fuel-injection pressure (as much as 2. 4 Method of operation of high-pressure components 5 Method of operation of high-pressure components of unit injector system of unit pump system 3 Fig. Robert Bosch GmbH Overview of diesel fuel-injection systems Designs 67 engines. pump system uses an electronically controlled fast-switching high-pressure solenoid valve (4) to regulate injection duration and start of injection. the hydro-mechanical or electronic The fuel-injection parameters are calculated control system is mounted directly on the by an electronic control unit and controlled engine block. ponents. the nozzle-and- by solenoid valves is also possible. In this case. it is Unit pump system (UPS) not possible to vary fuel-injection timing by The modular unit pump system (UPS) oper- adjusting the camshaft. It is to the engine. driven by the engine camshaft (6). In contrast with the unit adjustment range of a few degrees. 5 1 Nozzle 2 Nozzle-and-holder assembly 3 High-pressure fuel line æ UMK1766Y æ UMK1761Y 4 4 High-pressure 6 solenoid valve 5 Pump plunger 6 Drive cam . the unit achievable with in-line or distributor pumps. This separation of high-pressure jection pump and nozzle form a single unit generation and nozzle-and-holder assembly (Figure 4). Due to the fact that the pump is linked directly to the engine camshaft. The unit pump assemblies are Since there are no high-pressure fuel lines. bly (fuel-injection pump. fuel line and noz- rectly by a rocker arm driven by the engine zle-and-holder assembly) for each cylinder of camshaft. the engine. Control injector system. 4 1 Drive cam 1 2 2 Pump plunger 4 3 High-pressure 2 solenoid valve 3 1 5 4 Nozzle Fig. The injection pressure is largely independent of engine speed or injected-fuel quantity. the functions of pressure gener. 2 Fuel rail (pressure accumulator) æ UMK1762Y 3 High-pressure There is a nozzle (4) fitted in each cylinder solenoid valve of the engine. This system thus offers the greatest degree 4 Fig. The pressure is held in a pressure accumulator. 7 Examples of high-pressure components of Bosch diesel injection systems 2 3 1 Fig. 6 of flexibility in the choice of fuel-injection 1 High-pressure pump parameters. the “fuel 1 3 rail” (2). and is generated and controlled by a high-pressure pump (1). Robert Bosch GmbH 68 Overview of diesel fuel-injection systems Designs Common-rail (CR) system 6 Method of operation of high-pressure components In the common-rail accumulator fuel-injec. Start of injection and injected-fuel quantity are calculated by an electronic control unit. Fuel injection is effected by 5 4 Nozzle opening and closing the high-pressure sole- 5 Nozzle noid valve (3). of common-rail system tion system. 2 ation and fuel injection are separated (Fig- ure 6). 7 1 Unit injector Type P1 (cars) 2 Common-rail high- pressure pump Type CP3 (commercial 5 vehicles) 3 Fuel rail and nozzles (common-rail system for commercial vehicles) 4 4 Distributor injection pump Type VP30 (cars) 5 Control-sleeve æ UMK1767Y in-line fuel-injection pump Type RP39 10 cm (commercial vehicles) . this step was still a substantial risk for Bosch as there were still many difficul. the technological advancement of the diesel engine and its fuel-injection systems has continued unabated. Robert Bosch GmbH Overview of diesel fuel-injection systems History of diesel fuel injection 69 History of diesel fuel injection Development by Bosch of a fuel-injection sys. They were small. engine 1998 performance has been continually improved First unit injector system while noise and exhaust-gas emissions have for cars been consistently lowered. 1994 First unit injector system In 1962. the level of precision of the product was unmatched. In addition. 1996 First radial-piston creasing the injection pressure is a constant distributor injection challenge for developers. The technological omens were good: Bosch had 1927 experience with internal-combustion engines. 1962 First Type EP-VM ties to be overcome. 1997 In terms of fuel consumption and energy First common-rail injection system efficiency. æ UMK1753E . More than two decades later. Since that time. 1995 nated in the arrival of the electronically con. light. the compression-ignition engine remains the benchmark. above all. expertise developed in the production of lubrication pumps could be utilized. This has led to many pump more innovations in the design of fuel-injection systems (see graphic). First unit pump system trolled diesel fuel-injection system. New fuel-injection systems have helped to further exploit its potential. At the time. the distributor injection pump with for commercial vehicles automatic timing device developed by Bosch gave the diesel engine an additional boost. The pursuit of ever more precise metering of minute volumes of fuel delivered at exactly the right moment coupled with the aim of in. First volume-production its production systems were highly advanced in-line fuel-injection pump and. axial-piston distributor pump The first volume-production fuel-injection pumps appeared in 1927. and enabled diesel en- 1986 gines to run at higher speeds. These in-line First electronically fuel-injection pumps were used on commercial controlled axial-piston distributor pump vehicles from 1932 and in cars from 1936. many years of intensive development work at Bosch culmi. Nevertheless. Milestones in diesel fuel injection tem for diesel engines started in 1922. The fuel-injection system supplies the diesel engine with fuel. injected-fuel quantity and injection du- sary fuel pressure for injection and delivers ration. next with the aid of two control rods and thus double page).. arrangement enables the control of the start bined with a timing device. 12 cyl.8 cyl. a a large number of pump types (see Table 1.150 bar bustion chamber... 12 cyl. also includes the control-sleeve version (Type H)..200 bar the dispersal of fuel throughout the com. up to 1.. which allows the start-of-delivery The in-line fuel-injection pump is used all point to be varied in addition to the injec- over the world in medium-sized and heavy. the in-line fuel-injection pump Type H1 for 6..200 bar ria in that regard are Type ZW(M) for 4 . up to 950 bar the timing and duration of fuel injection Type P9 for 6. 200 kW per cylinder (see also Table 1 in the chapter “Overview of diesel fuel-injection systems”). As a result.300 bar which the fuel is introduced into the com. Over the years..... It is controlled either by which has two actuator mechanisms. They are equally suitable for use Areas of application on direct-injection (DI) or indirect-injection (IDI) engines. of injection and the injected-fuel quantity tronic actuator mechanism (Table 1.. it is capable of handling poorer fuel qualities. trolled by a Type RE electronic controller installation engines. the following versions are available: the fuel at the required rate. Type R for 4 . . The particular strength of these engines with anything from 2 to 12 cylinders pumps is their rugged durability and ease and ranging in power output from 10 to of maintenance. For that reason. up to 750 bar the nozzle... makes the automatic timing device superflu- In contrast with all other fuel-injection ous. 8 cyl.. which may be com. They are used on diesel use today.350 bar system. up to 1. The fuel is Type M for 4 .12 cyl. tion quantity. Type CW for 6 . 12 cyl. The Type H pump is con- duty trucks as well as on marine and fixed. this system has been The range of standard in-line fuel-injection continually refined and adapted to suit its pumps currently produced encompasses many areas of application.200 bar processes in a diesel engine are primarily Type P8000 for 6 . up to 1.000 bar bustion chamber The version most commonly fitted in com- the point at which ignition is initiated mercial vehicles is the Type P.300 bar is lubricated by the engine’s lubrication Type H1000 for 5 . up to 1.. The most important crite... Robert Bosch GmbH 70 Overview of in-line fuel-injection pump systems Areas of application. Depending on the required injection pres- the fuel-injection pump generates the neces. The following versions are available: systems. The combustion Type P7100 for 4. large variety of different versions are still in next double page). 12 cyl. 12 cyl.300 bar dependent on the quantity and manner in Type P8500 for 4 . To perform that function. sure. Standard in-line fuel-injection pumps ogy. up to 1..... 10 cyl. up to 1.12 cyl. 6 cyl. This a mechanical governor.. the volume of fuel injected relative to crankshaft rotation. up to 1... up to 550 bar pumped through a high-pressure fuel line to Type A for 2 . up to 1. and Control-sleeve in-line fuel-injection pump the total volume of fuel injected relative The range of in-line fuel-injection pumps to the desired power output of the engine.12 cyl. Type P10 for 6.. up to 950 bar combustion chamber. which injects it into the engine’s Type P3000 for 4 . or by an elec. 12 cyl. Types Overview of in-line fuel-injection pump systems No other fuel-injection system is as widely Types used as the in-line fuel-injection pump – the “classic” diesel fuel-injection technol.. up to 1. The Type RQ maximum-speed governor limits the maximum speed. teristics are required of the governor: holder assemblies. 1 11 Fuel tank 4 12 Fuel filter with overflow valve 7 8 (option) 2 13 Timing device 6 3 14 In-line fuel-injection 9 pump 15 Fuel pump (mounted 5 10 on injection pump) 16 Governor 17 Accelerator pedal 11 18 High-pressure fuel line 19 Nozzle-and-holder 12 æ UMK0784-1Y assembly 10 Fuel-return line 11 Type GSK glow plug 12 Type GZS glow plug control unit 13 Battery 1 13 14 15 14 Glow plug/starter switch (“ignition switch”) 15 Diesel engine (IDI) . a mechanical governor or electronic control system for controlling the engine Mechanical governors speed and the injected-fuel quantity Mechanical governors used with in-line a timing device (if required) for varying fuel-injection pumps are centrifugal gover- the start of delivery according to engine nors. Robert Bosch GmbH Overview of in-line fuel-injection pump systems Design. different control charac- a corresponding number of nozzle-and. The engine’s torque output is the fuel tank through the fuel filter and approximately proportional to the quantity the fuel line to the injection pump of fuel injected per piston stroke. it sponding to the number of cylinders in operates the pump’s control rod. On its output side. This type of governor is linked to the speed accelerator pedal by means of a rod linkage a set of high-pressure fuel lines corre. Control 71 Design Control Apart from the in-line fuel-injection pump. all of those components must be mum-speed governors also control the matched to each other. 1 Fuel-injection system with mechanically governed standard in-line fuel-injection pump Fig. In order for the diesel engine to function The Type RQ and RQU minimum/maxi- properly. and on the type of use. The operating parameters are controlled the complete diesel fuel-injection system by the injection pump and the governor (Figures 1 and 2) comprises which operates the fuel-injection pump’s a fuel pump for pumping the fuel from control rod. and an adjusting lever. idle speed in addition to limiting the maximum speed. Depending the engine. By means of electrical compensate for the time taken by the pres. more precise metering of fuel delivery. there rack sensor and speed sensor is an accelerator-pedal sensor which is con. measuring processes. Electronic control of diesel engines im- 19 Nozzle-and-holder nected to the electronic control unit. for FGR. An electronic control system performs sig- Timing devices nificantly more extensive functions than the In order to control start of injection and mechanical governor..K. standard in-line fuel-injection with electrical actuators. Diesel-engine load and speed Electronic diesel control systems can also 16 Fuel-temperature are controlled by the injected-fuel quantity exchange data with other electronic control sensor without exerting any throttle action on the systems on the vehicle (e. System. it enables more 13 Type ELAB electric pumps use a timing device which “advances” comprehensive response to variable factors shut-off valve the start of delivery of the fuel-injection than is possible with the mechanical gover- 14 In-line fuel-injection pump as the engine speed increases. HGB or ZDR 12 13 21 Tachograph or vehi- 24 cle-speed sensor 22 Switch on clutch. e. electronic transmission control) and actuator mechanism can therefore be integrated in a vehicle’s 18 Fuel-quantity posi. a load-dependent control system 15 Fuel pre-delivery pump is employed. trol the intermediate speed range. 23 brake pedal æ UMK0657-1Y 23 Battery 19 20 21 22 25 24 Diagnosis interface 25 Glow plug/starter 1 switch (“ignition switch”) . 10 Glow plug position signal into a corresponding nomi- 11 Engine-temperature sensor (in coolant 2 Fuel-injection system with electronically controlled control-sleeve in-line fuel-injection pump system) 12 Crankshaft-speed 14 sensor 13 Diesel engine (DI) 15 14 Type GZS glow control unit 4 7 15 Engine control unit 9 16 Air-temperature sensor 3 6 8 17 Boost-pressure 2 sensor 10 16 17 18 18 Turbocharger 19 Accelerator-pedal 5 sensor 11 20 Operating unit. RQUV. pump cial cases. tioner with control- If an electronic control system is used. nor. EDR. account the engine speed. flexible electronic data Fig. In spe. Traction Control 17 Start-of-delivery intake air. brake and engine. RSV and nal control-rack travel while taking into RSUV variable-speed governors also con. RQV.g. 2 11 Fuel tank sure wave to travel along the high-pressure processing and closed-loop control systems 12 Fuel filter fuel line. Electronic control systems overall system network.g. The proves their emission characteristics by assembly control unit then converts the accelerator. Robert Bosch GmbH 72 Overview of in-line fuel-injection pump systems Control The Type RQV. Variable-speed governor Type RSUV – – – – – 2) Same design as Type Type RE (electric actuator mechanism) – – – – P but for heavier duty. Robert Bosch GmbH Overview of in-line fuel-injection pump systems Control 73 1 Areas of application for the most important in-line fuel-injection pumps and their governors and agricultur- Fixed-installa- Railway loco- Construction al machinery tion engines Commercial vehicles Area of application motives Ships Cars Pump type Standard in-line fuel-injection pump Type M – – – – Standard in-line fuel-injection pump Type A – – – – Standard in-line fuel-injection pump Type MW 1) – – – – Standard in-line fuel-injection pump Type P – Standard in-line fuel-injection pump Type R 2) – – Standard in-line fuel-injection pump Type P10 – – Standard in-line fuel-injection pump Type ZW(U) – – – – Standard in-line fuel-injection pump Type P9 – – Standard in-line fuel-injection pump Type CW – – – – Control-sleeve in-line fuel-injection pump Type O – – – – – Governor type Minimum/maximum speed governor Type RSF – – – – Minimum/maximum speed governor Type RQ – – – – Minimum/maximum speed governor Type RQU – – – – – Variable-speed governor Type RQV – – – Table 1 Variable-speed governor Type RQUV – – – – 1) This type of pump is Variable-speed governor Type RQV.K – – – – – no longer used with Variable-speed governor Type RSV – – – – new systems. 3 Pump types: a ZWM (8 cylinders) b CW (6 cylinders) c H (control-sleeve type) æ NMK1813Y (6 cylinders) f 20 cm d P9/P10 (8 cylinders) e P7100 (6 cylinders) f A (3 cylinders) . 3 Examples of in-line fuel-injection pumps b a d c e Fig.. An increase in the fuel-injection pressure was required in order to achieve Three types of distributor injection pump lower fuel consumption and exhaust-gas are distinguished according to the method emissions on engines with direct injection. The pump and its control system have been continually improved over that Designs period. tion pumps meet those requirements. Solenoid-valve-controlled injection pumps tor injection pumps are used. the most widely used fuel-injection pump for cars. commercial vehicles. The fuel is deliv. It generates the necessary fuel characteristic feature of distributor injection pressure for fuel injection. The fuel- injection pump plays a decisive role in that Apart from their compact dimensions. machinery (off-road vehicles). actuator mechanisms. the nozzle. while radial-piston types are suit- Areas of application able for outputs of up to 45 kW per cylinder. fixed-installation en- tion chamber. which in turn inject it into the combus. injection system capable of rapid injection The rated speed. Distributor injection pumps are lubri- Since its introduction in 1962. model of distributor injection pump chosen. Designs Overview of distributor fuel-injection pump systems The combustion processes that take place by electronic control systems with electrical inside a diesel engine are essentially depen. high-pressure fuel-injection pump and control mechanism. and construction and agricultural engines require a high-performance fuel. They produce A high-pressure solenoid valve opens and pressures of up to 900 bar (90 MPa) for closes the high-pressure chamber outlet. cated by the fuel and are therefore mainte- ton distributor injection pump has become nance-free. power output and design sequences. and up to 1900 bar thereby controlling start of injection and (190 MPa) for fast-running diesels. that is also light in weight and of the diesel engine determine the type and compact in dimensions. high-pressure solenoid valves were developed. Later on. between 1962 and 2001. injection duration. channels and slide valves. ered by the fuel-injection system. which allows them to be used on cars. Radial-piston distributor injection pumps are always controlled by The mechanical governors originally used on solenoid valves. type of control A total of more than 45 million distributor system and method of high-pressure genera- injection pumps were produced by Bosch tion (Figure 1). slow-running engines. the connection. A with indirect injection (IDI) generate pres. They They are used on engines with between consist of a small. distributor injection pumps were succeeded . the axial-pis. pumps with dent on the way in which the fuel is deliv. The available designs and overall system configurations are Method of fuel-quantity control accordingly varied. pumps is their versatility of application ered via high-pressure fuel lines to the noz. both axial-piston and radial-piston distribu. light zles. compact unit comprising 3 and 6 cylinders. of fuel-quantity control. Axial-piston distributor pumps are used on engines with power outputs of up to 30 kW per cylinder. For direct-injection (DI) engines. Port-controlled injection pumps The injection duration is varied by means of Axial-piston distributor pumps for engines control ports. the fuel pump. fast-running diesel gines. Distributor injec. hydraulic timing device varies the start of sures of as much as 350 bar (35 MPa) at injection. Small. Robert Bosch GmbH 74 Overview of distributor fuel-injection pump systems Areas of application. g. engine coolant ton which moves in an axial direction rela. trol systems (e. and fuel. higher power output and torque by virtue Type of control system of more precise control of fuel quantity Mechanical governor and start of injection.g. vacuum to auxiliary systems (e. idling. pedal (sensor). etc. cruise The driver signals the desired torque output/ control).).g. therefore integration in the vehicle’s count of the current engine operating status overall control network. EDC VE . springs. crankshaft Type VE axial-piston distributor pumps position and speed. traction control system. 1 Types of distributor injection pump Distributor injection pumps Fuel- quantity Port-controlled Solenoid-valve controlled control Control Mechanically controlled Electronically controlled (EDC) method Generation of high Axial-piston pump Radial-piston pump pressure æ NMK1794E VE . heating function. These compress the fuel by means of a pis. charge-air pressure control. engine speed by means of the accelerator Improved diagnostic functions. air conditioning) actuators.. Using that stored information and the Data exchange with other electronic con- actual values from the sensors. Radial-piston pumps can offers many advantages over a mechanical produce higher pressures than axial-piston governor: versions.. tings for the fuel-injection pump actuators electronic transmission control) and are calculated. temperature of intake air. The fuel-injection pump is controlled by a Lower idling speed and ability to adjust governor linked to levers. tronic engine immobilisation). These compress the fuel by means of several pistons arranged radially in relation to the The EDC (Electronic Diesel Control) system pump drive shaft. smooth-running control. elec- characteristics. lower emissions. smoke limits and pump tion. Lower fuel consumption. exhaust-gas recircula- erator characteristics.. The con- tive to the pump drive shaft. The resulting settings take ac. active surge Electronic control system damping. etc. Greater sophistication (e. MV VR . specified set. charge-air pressure. pre- data maps for starting.g. trol unit then operates the actuators or the solenoid valves in the fuel-injection pump Type VR radial-piston distributor pumps according to the required settings. F VE . Robert Bosch GmbH Overview of distributor fuel-injection pump systems Designs 75 Method of high-pressure generation and the ambient conditions (e. full load. vehicle road speed. accel. by virtue of better control of engine speed.g. Stored in the control unit are Additional control functions (e. the idle speed.F 11 Fuel supply line 12 Linkage 2 13 Accelerator pedal 14 Distributor injection 1 3 pump 15 Type ELAB electric 5 6 shut-off valve 16 High-pressure 4 fuel line 17 Fuel-return line 7 8 18 Nozzle-and-holder assembly 19 Type GSK glow plug 9 10 Fuel filter 10 11 Fuel tank 12 Fuel pump (only 11 in the case of long fuel lines or large 15 12 vertical separation between fuel tank and fuel-injection pump) 13 Battery 14 Glow plug/starter æ UMK1199-1Y switch (“ignition switch”) 13 14 16 15 Type GZS glow control unit 16 Diesel engine (IDI) . essentially determines the injection pattern case. precisely the oppo- and relatively straightforward to maintain. 6 and 7). atmospheric pressure The type designation VE. Fig. The Type ELAB elec- valve is open when high-quality mixture formation. In that Mechanical governing responds to differ. the fuel pump (12). In addition. assemblies. the fuel injection pumps filter (10). the shut-off ences in operating status and guarantees and the spray pattern. Robert Bosch GmbH 76 Overview of distributor fuel-injection pump systems Port-controlled systems Port-controlled systems In addition to the fuel-injection pump (4).1) status of the following engine operating The accelerator pedal (3) and a cable or parameters: rod linkage (2) transmits the driver’s desired engine speed engine response to the fuel-injection pump engine load governor. and controlled by additional mechanisms. the nozzle- Mechanical governing is used only with ax. Additional tric shut-off valve (5) cuts off the fuel supply de-energized. control linkages vary the start of injection to the pump’s high-pressure chamber when and injection quantity to suit the current the “ignition” is switched off. the overall diesel fuel-injection system (Fig- Mechanically governed distributor ure 1) consists of the fuel tank (11).. A major role is played by the 1) is the fact that it is economical to produce injector nozzles in the nozzle-and-holder On marine engines.. The design of the injector nozzle site is true. inter- engine temperature mediate speeds and maximum speed can be charge-air pressure. Its advantage (1. 1 1 Fuel-injection system with mechanically governed axial-piston distributor pump Type VE. and-holder assemblies (8) and the fuel lines ial-piston distributor pumps.F is used for distributor injection pumps that are controlled by a centrifugal (flyweight) governor. chanically governed fuel-injection pump. control unit and actua. turbocharger. and response. As with the me- capable of processing a wider range of vari. injection pumps exhaust-gas recirculation. 2 Figure 2 shows the components of a fully control unit calculates the setting for the 11 Fuel tank 12 Fuel filter configured fuel-injection system with an fuel-injection pump’s solenoid actuator on 13 Distributor injection electronically controlled axial-piston distrib. the ports are opened sooner or later depend- not take account of. The Fig. actuator. flexible mechanical governor and linkages.EDC cylinder no. adjustment omitted depending on the type of application An angle sensor (e.g. the basis of stored data maps and the actual pump with solenoid utor pump. sensor the fuel-supply system (low-pressure tion of the control collar to the control unit. ing on the position of the control collar. and glow con- The electronic control system EDC takes ac. a semi-differential travel sensor and and vehicle concerned. the distributor injection pump replaces the By the use of electrical detectors. 16 Nozzle-and-holder up of the sensors. it is control sleeve via a shaft. 14 Type ELAB electric shut-off valve system) The speed-dependent internal pump- 15 Timing-device the fuel-injection pump chamber pressure acts by way of a cyclically solenoid valve the electronic control system EDC made actuated solenoid valve on the timing de. needle-motion sensor (usually on 2 Fuel-injection system with electronically controlled axial-piston distributor pump Type VE. count of additional demands on top of those The solenoid actuator (rotary actuator) on accommodated by the mechanical governor. Robert Bosch GmbH Overview of distributor fuel-injection pump systems Port-controlled systems 77 Electronically controlled distributor the peripheral systems (e. which varies the start of injection in assembly with tors. 1) 17 Type GSK glow plug 22 18 Engine-temperature sensor (in coolant 1 system) 19 Crankshaft-speed 19 sensor 10 Diesel engine (DI) 11 Engine control unit 6 20 21 12 Type GZS glow 2 3 control unit 13 Vehicle-speed 7 sensor 4 14 Accelerator-pedal sensor 8 15 Operator unit for cruise control 5 16 Glow plug/starter 9 10 switch (“ignition switch”) 17 Battery 18 18 Diagnosis interface 19 Air-temperature 13 14 15 sensor æ UMK1797Y 11 12 20 Charge-air pressure 16 17 sensor 21 Turbocharger 22 Air-mass meter . It varies electronic data processing and closed-loop the injected-fuel quantity by operating the control circuits with electric actuators. Certain components may be values from the sensors. The system consists of short-circuiting ring sensor) signals the angular fuel-temperature four sections: position of the actuator and therefore the posi.. vice.g. able factors that a mechanical governor can. trol unit). up of the sensors. control unit(s) and actuators. sensors. Secondly. Air intake and pressure system) exhaust-gas systems System with EDC separate control units Engine Signals High-pressure system æ NMK1795E Diesel fuel . Robert Bosch GmbH 78 Overview of distributor fuel-injection pump systems Solenoid-valve-controlled systems Solenoid-valve-controlled Control-unit configuration Separate control units systems First-generation diesel fuel-injection systems Solenoid-valve-controlled fuel-injection sys.. with solenoid-valve-controlled distributor tems allow greater flexibility in the metering injection pumps (Types VE. and While the pump control unit receives the the air-intake and exhaust-gas systems internal pump-sensor signals for angle of (air intake. by having short control the fuel-supply system (low-pressure system) lines for the solenoid valve.MV [VP30]. injected-fuel quantity.MV [VP29] injection than port-controlled systems.. interfaces Integrated control unit Fuel supply (low. They for IDI engines) require two electronic con- also permit pre-injection for noise reduction trol units (ECUs): a Type MSG engine con- purposes and cylinder-specific correction of trol unit and a Type PSG pump control unit. emission control and exhaust. VR of fuel delivery and the variation of start of [VP44] for DI engines and VE. them for the purposes of adjusting the start 1 Components of an engine-management system with a solenoid-valve-controlled fuel-injection pump EDC Electronic Diesel Control: engine management. it prevents A fuel-injection system using a solenoid. There are two reasons for separation of the control units in this way: Firstly. rotation and fuel temperature and analyzes gas recirculation). certain electronic components from over- valve-controlled distributor injection pump heating by being very close to the engine and can be subdivided into four areas (Figure 1): pump. it eliminates the the high-pressure system including all the effect of interference signals which can oc- injection components cur as a result of the high currents (up to 20 the electronic control system EDC made A) that are generated. some vehicles will need separate Heat-resistant hybrid printed-circuit boards emission-control systems. pre-injec- The engine control unit and pump con. tant among them are dealt with in a separate chapter. Integrated control unit however. 2 Example of a diesel fuel-injection system with solenoid-valve-controlled radial-piston distributor pump and separate engine and pump control units 2 1 4 Fig. shape the injection pattern (e. have made it possible to integrate the engine control unit in the pump control unit on Various emission-control systems are cur- second-generation solenoid-valve-controlled rently under development. Robert Bosch GmbH Overview of distributor fuel-injection pump systems Solenoid-valve-controlled systems 79 of injection. This method of will eventually become established is as yet control-unit integration allows a more an unanswered question.g. The most impor- space-saving design. the engine-management mod. Emission control ule processes all engine and ambient-condi. These include such things to calculate the actuator adjustments to be as exhaust-gas recirculation. Which of them distributor injection pumps. Various features improve exhaust emission tions data from external sensors and uses it characteristics. order to be able to meet the ever more stringent exhaust-gas emission requirements. tion) and the higher injection pressure. 2 3 11 Engine control unit 12 Type GZS glow 5 control unit 13 Fuel filter 6 14 Air-mass meter 15 Nozzle-and-holder assembly 7 16 Type GSK glow plug 17 Type VP44 radial- piston distributor injection pump with PSG5 pump control unit 8 9 10 11 18 Alternator 19 Engine-temperature sensor (in coolant æ UMK1206-1Y system) 10 Crankshaft-speed sensor 11 Accelerator-pedal sensor . the ability to made on the fuel-injection pump. In trol unit communicate via a CAN interface. not shown in their fitted positions. Even the instrument cluster (12) and the air- For the sake of clarity of the diagram. 3 Engine. Fig. VTG) A Sensors and setpoint generators 28 Charge-air pressure actuator 11 Accelerator-pedal sensor 12 Clutch switch E Emission control 13 Brake switches (2) 29 Diesel oxidation-type catalytic converter 14 Operator unit for cruise control 15 Glow plug/starter switch (“ignition switch”) 16 Vehicle-speed sensor 17 Crankshaft-speed sensor (inductive) 18 Engine-temperature sensor (in coolant system) 19 Intake-air temperature sensor 10 Charge-air pressure sensor 11 Hot-film air-mass meter (intake air) B Interfaces 12 Instrument cluster with signal output for fuel consumption. The only exception to this is the needle-motion sensor (21). The diagram shows the fully config. the traction control system TCS. 13 Air-conditioning compressor with control 14 Diagnosis interface 15 Glow control unit CAN Controller Area Network (vehicle’s serial data bus) . the conditioning system (13) can be connected sensors and desired-value generators (A) are to the CAN bus. engine speed. some of the components the electronic stability program ESP may not be used. Robert Bosch GmbH 80 Overview of distributor fuel-injection pump systems Solenoid-valve-controlled systems System diagram The CAN bus in the interfaces section (B) Figure 3 shows an example of a diesel fuel. The pump is fitted with the alternator an engine control unit and pump control the electronic immobilizer unit. engine control unit and high-pressure C Fuel supply (low-pressure system) fuel-injection components 19 Fuel filter with overflow valve 16 Fuel-injection-pump drive 20 Fuel tank with pre-filter and fuel pump (only required 17 Integrated engine control unit/pump control unit with long fuel lines or large vertical separation between Type PSG16 fuel tank and fuel-injection pump) 18 Radial-piston distributor injection pump (VP44) 21 Nozzle-and-holder assembly with needle-motion sensor D Air supply (cylinder no. the transmission control system ured system. 1) 24 EGR valve and EGR positioner 22 Glow plug 25 Vacuum pump 23 Diesel engine (DI) 26 Control flap M Torque 27 Turbocharger (in this case with variable turbine geometry. riety of systems and components including piston distributor pump on a four-cylinder the starter motor diesel engine (DI). etc. Depending on the type of vehi. and cle and application. enables exchange of data between a wide va- injection system using a Type VR radial. Robert Bosch GmbH Overview of distributor fuel-injection pump systems Solenoid-valve-controlled systems 81 3 Diesel fuel-injection system with Solenoid-valve-controlled radial-piston distributor pump Type VP44 and integrated engine control unit and pump control unit Type PSG16 B CAN C 12 19 13 17 16 20 14 15 18 A 1 21 22 2 3 23 4 M 5 24 D 6 26 7 25 8 27 28 9 10 E 29 æ NMK1796Y 11 . These versions are economy.Power generators . gines with outputs of between 75 kW and gines must offer low emissions.Railway locomotives .Commercial vehicles . The short high-pressure fuel Type PF discrete injection pumps are partic- lines enable the achievement of particularly ularly easy to maintain. diesel fuel and heavy oil. each of which is suited to fuel-injection pumps for large-scale en- different requirements. They are used in the good injection characteristics and extremely “off-highway” sector as high injection pressures.Construction and . ate in the same way as Type PE in-line fuel- noid-valve controlled unit injector and unit injection pumps. Those systems differ not only unit on which the injection quantity can be in their design but also in their performance varied by means of a helix. and injection systems. and the sole. Robert Bosch GmbH 82 Overview of discrete cylinder systems Single-plunger fuel-injection pumps PF Overview of discrete cylinder systems Diesel engines with discrete cylinder systems Single-plunger fuel- have a separate fuel-injection pump for each cylinder of the engine.Ships .Tractors agricultural machinery æ NMK1873E . Each discrete fuel-injection pump is sepa- rately flanged-mounted to the engine and driven by the camshaft that controls the en- 1 Discrete cylinder system designs and areas of application Discrete cylinder systems Fuel- quantity Port-controlled Solenoid-valve controlled control Control Mechanical/hydraulic Electronic method Type PF discrete injection Type pumps Unit pump system (UPS) Unit injector system (UIS) Area .Heavy-duty trucks . the development of a variety of diesel fuel. fuel-injection pumps for diesel engines with outputs of 4…75 kW/cylinder in Continually increasing demands have led to small construction-industry machines.000 kW per cylinder. Such individual fuel- injection pumps PF injection pumps are easily adaptable to par. Modern diesel en.Ships . tractors and power generators. good fuel 1. pumps. They have a single pump pump systems.Railway locomotives . data and areas of application (Figure 1). high torque and power output capable of working with high-viscosity while also being quiet-running.Cars of use . There are basically three types of discrete Design and method of operation cylinder system: the Type PF port-controlled Type PF discrete fuel-injection pumps oper- discrete fuel-injection pump. Application ticular engines.Pumps .Construction machinery . Fig. injection viscosity of 10. 150 °C. In such cases they have The fuel is filtered by fine-pore filters with the type designation PFR.. cause premature wear on the part of the high-precision fuel. in 2. a con. In order to do so.20 mm2/s is purely mechanical governors. 2 a Type PFE 1 for b small engines a b Type PFR 1 for æ UMK0455-1Y small engines c Type PFR 1 W for large-scale engines d Type PF 1 D for large-scale engines . to be pre-heated to temperatures as high as dro-mechanical governors or electronic con.5 times as much fuel as the majority of designs supply only a single the maximum full-load delivery of all indi- cylinder and are therefore known as discrete vidual fuel-injection pumps. Heavy oil operation trol rod incorporated in the engine acts on Discrete fuel-injection pumps for engines the fuel-injection pump units. The fuel is fed to the individual fuel-injec- Some of the smaller Type PF pumps come tion pumps by a gear-type presupply pump. They are thereby varying the fuel delivery and also suitable for use with high-viscosity injected-fuel quantity. the governor is at 50 °C. This ensures that the required fuel- trol systems may be used.. in the event that the adjusting mechanism on one of the pumps jams. Such particles would otherwise the type designation PFE..10 bar. It delivers around 3. They fuel-injection pumps. 10 cm Fuel supply Supply and filtering of the fuel and removal of air from the fuel-injection system is performed in the same way with Type PF dis.30 µm in order to keep sus- signs for smaller engines. the roller tappet is pended particles out of the fuel-injection mounted on the engine. a pore size of 5.. Between the control rack for the discrete fuel-injection pumps and the actuating linkage from the governor. or more rarely. Those versions have system. The fuel pres- or cylinder fuel-injection pumps. Hy. not only used to pump diesel fuel. Robert Bosch GmbH Overview of discrete cylinder systems Single-plunger fuel-injection pumps PF 83 gine valve timing. Many discrete fuel-injection pumps have an integral roller tappet. sure in this part of the system is around 3. may also be referred to as plug-in pumps..injection components.. the heavy oil has mounted directly on the engine block. 3 and 4-cylinder versions.. They can therefore be crete fuel-injection pumps as for in-line described as externally driven pumps. obtained. With some de. However.. there is a sprung 2 Examples of Type PF discrete fuel-injection pumps compensating link so that. control of the c d other pumps is not compromised. heavy oils with viscosities up to 700 mm2/s On large-scale engines. Control As with in-line fuel-injection pumps. A governor or with outputs of over 100 kW/cylinder are control system moves the control rack. unit injector system has excellent hydraulic The air-intake and exhaust-gas-systems characteristics. railway locomotives in 1994 and for cars in 1998. the interfaces. direct injection (DI) diesel engines. The UPS12 for commercial-vehicle en- nomical and quiet to run. outputs of up to 35 kW/cylinder The UPS20 for heavy commercial-vehicle Areas of application engines with up to 8 cylinders and power Unit injector system (UIS) outputs of up to 80 kW/cylinder The unit injector system (UIS) went into UPS for engines in construction and agri- volume production for commercial vehicles cultural machinery.MV for large- The unit injector and unit pump fuel-injec. There tus. control unit and actua- heavy-duty trucks developing up to tors performs all diesel engine manage- 80 kW/cylinder. The modular design of the individual subsystems allows the entire fuel-injection system to be easily adapted to individual engine designs. fuel-injection pumps for diesel engines with direct injection (DI). ing of the sensors. 5 l the fuel into the combustion chamber. are eco. tion systems achieve the highest injection pressures of all diesel fuel-injection systems Like the unit injector system. It can be used on are made up of four subsystems (Figure 1): a wide range of modern diesel engines for The fuel supply system (low-pressure sys- cars and commercial vehicles extending to tem) provides suitably filtered fuel at the cars and light commercials with engines correct pressure. are three versions: tems produce low emission levels. This system offers a Design significantly greater degree of adaptability to System structure individual engine designs than conventional The unit injector and unit pump systems port-controlled systems. It is a fuel-in. unit injector system for cars also offers the option of pre-injection.2 l units The high-pressure system generates the producing 45 kW (61 bhp) of power and necessary injection pressure and injects 195 Nm of torque to 10-cylinder. Robert Bosch GmbH 84 Overview of discrete cylinder systems Unit injector system (UIS) and unit pump system (UPS) Unit injector system (UIS) Unit pump system (UPS) The unit pump system (UPS) is also referred and unit pump system (UPS) to by the type designation PF. They are capable of system is a fuel-injection system with timer- high-precision fuel injection that is infinitely controlled discrete fuel-injection pumps for variable in response to engine operating sta. and ships with power outputs of up to jection system with timer-controlled discrete 500 kW/cylinder and up to 20 cylinders.050 bar). ment and control functions as well as providing all electrical and electronic As it requires no high-pressure fuel lines. The treatment. scale engines.. Diesel engines equipped with these sys. . and offer high gines with up to 8 cylinders and power performance and torque characteristics. That is the reason why this handle the supply of air for combustion. system is capable of producing the highest exhaust-gas recirculation and exhaust-gas injection pressures (up to 2. ranging from three-cylinder 1. engines with power outputs of 230 kW The EDC electronic control system consist- (bhp) and torque levels of 750 Nm. the unit pump currently available. This arrangement has advan- fitted in each cylinder of the engine. sensors. As there tages in terms of use of space. Robert Bosch GmbH Overview of discrete cylinder systems Unit injector system (UIS) and unit pump system (UPS) 85 Differences and precisely controlled injection patterns The essential difference between the unit can be produced. high injection pressures can be generated 1 Structure of unit injector and unit pump systems Electronic Diesel Control EDC: engine management. interfaces Fuel supply Air intake and High-pressure system (low-pressure system) exhaust-gas systems æ NMK1724-1E Engine Signals Diesel fuel Fig. injector system and the unit pump system lies in the way in which high pressure is With the unit pump system. and servicing and maintenance. pump-drive are no high-pressure fuel lines. 2 2 High-pressure generation in unit injector and unit pump systems a Unit injector system for cars b Unit injector system a b c for commercial vehicles c Unit pump system 1 1 for commercial 6 2 vehicles 2 3 7 3 1 Rocker arm 4 4 5 2 Camshaft 3 3 High-pressure 5 solenoid valve 5 8 4 Unit injector 5 Engine combustion chamber 2 6 Nozzle-and-holder æ UMK1874Y assembly 7 Short high-pressure line 8 Unit pump . There is a unit injector pressure pipe. the high-pres. the high pres- generated (Figure 2). sure pump – the “unit pump” – and the noz- In the unit injector system. zle-and-holder assembly are separate units sure pump and the nozzle form a single unit that are connected by a short length of high- – the “unit injector”. extremely system. the pressure is dissipated and the be dynamically allocated to one or other of nozzle closes again. there is rocker arms running off the camshaft. For some commercial- charge-air pressure vehicle applications. and in particular the opera. Other functions can opens.g. recording of sensor signals). When the solenoid valve (e. The length of time the valve re. For engines with more than six cylinders. Some functions are perma- high-pressure pump generates pressure and nently allocated to a specific control unit the nozzle opens. A diagnosis interface enables analysis of grammed engine data maps. The calculation stored system data when the vehicle is ser- process also takes account of the current en. the control units as situations demand (e.g. With this stages for controlling the solenoid valves. information. The point at which the sole. In addition to the input circuitry and the microcontroller. Master-and-slave configuration tion of the engine. volume balancing). quantity and pressure. etc. the control unit is able to control the vehicle. gine operating status and the ambient conditions. low-consumption and smooth-running characteristics. As a result. The input data includes the following: Control unit configuration accelerator pedal position The Type MSG engine control unit is fitted crankshaft angle of rotation inside the engine compartment (partially camshaft speed engine-mounted). the These parameters are recorded by sensors control unit also incorporates all output and processed by the control unit. the piston in the pacity available. They are linked via a dedi- The high-pressure pumps are driven directly cated high-speed CAN interface in a master- by one of the engine’s camshafts or by and-slave configuration. stages for the injectors. Some examples are: which the valve closes – determines the start Exhaust-gas recirculation of delivery. . While also a higher microcontroller processing ca- the solenoid valve is closed. (control unit cooler). two engine control Generation of high pressure units are used. Charge-air pressure control mains closed is a measure of the injected-fuel Cruise control quantity. Robert Bosch GmbH 86 Overview of discrete cylinder systems Unit injector system (UIS) and unit pump system (UPS) Method of operation Additional functions UIS and UPS are both diesel fuel-injection Additional control functions perform the systems that use timer-controlled integral tasks of reducing exhaust-gas emissions and solenoid valves. Control Basic functions The basic functions involve the precise control of injection timing. engine coolant electronic components has to be dissipated and fuel through an integral heat sink to the fuel vehicle road speed. fuel consumption or providing added safety noid valve is actuated – and consequently at and convenience. The valve actuation point and Electronic immobilizer closed period are determined by the electronic control unit on the basis of the pro. the heat given off by the temperature of intake air. they ensure that the diesel engine has low-emission. in such a way as to ensure Present-day control units contain six output optimum efficiency. viced. In this way. . 3 1 Nozzle æ UMK1875Y 2 High-pressure solenoid valve 3 Ball pin for driving 1 pump plunger sions. This method has been the state of the NOX accumulator-type catalytic converters art for diesel cars for a number of years. 3 gines. Robert Bosch GmbH Overview of discrete cylinder systems Unit injector system (UIS) and unit pump system (UPS) 87 Air-intake and exhaust-gas systems This is particularly true for larger cars and Exhaust-gas recirculation for cars commercial vehicles. They can then reduce not only The vast majority of modern diesel engines NOX but also HC. Fig. The SCR (selective catalytic reduction) cat- exhaust gas is recirculated at low engine loads alytic converters. There are many sys- Exhaust-gas recirculation is an effective tems currently in the process of develop- method of reducing NOX components in the ment. additional features such as turbochargers with variable turbine geometry (VTG). In combination systems (also called four-way Exhaust-gas recirculation for systems). Such systems demand very powerful engine management systems. exhaust-gas treatment will become increasingly important for diesel engines in the future despite advances in internal engine design. CO and particulate emis- are fitted with exhaust-gas turbochargers. If the recirculated exhaust Diesel-oxidation catalytic converters gas is also cooled. Since exhaust-gas recirculation and cooling cannot be 2 dispensed with even at the higher end of the load curve on commercial-vehicle en. several individual systems are commercial vehicles combined. wastegates or flutter valves are necessary. The most important emission control Exhaust-gas treatment systems are dealt with in a separate chapter. Such engines do not generally have a negative pressure differential between the exhaust manifold upstream of the turbine and 3 Example of a unit injector for cars the inlet manifold downstream of the compressor at high engine loads. The possibilities include: intake manifold. Which of them will eventually be- exhaust gas. and speeds. It involves the use of a valve come established remains an unanswered which returns some of the exhaust gas to the question. further advantages can be Various particulate filters (PF) gained. In order to be able to comply with stricter emission-control legislation. 1 Engine. conditioning system (13) can be connected ceptions to this are the components of the to the CAN bus. engine speed. TCS and the electronic stability program ESP For the sake of clarity of the diagram. exhaust-gas treatment systems (F) as their proper fitted positions are necessary in order For emission control. the sensors and desired-value generators (A) Even the instrument cluster (12) and the air- are not shown in their fitted positions. Robert Bosch GmbH 88 Overview of discrete cylinder systems System diagram of UIS for cars System diagram of UIS The CAN bus in the interfaces section (B) enables exchange of data between a wide va- for cars riety of systems and components including: Figure 1 shows all the components of a fully the starter motor equipped unit injector system for an eight. the alternator cylinder diesel car engine. Fig. some of the the transmission control system components may not be used. bination systems are shown (a. the traction control system. Depending on the the electronic immobilizer type of vehicle and application. 41 Exhaust heater 13 Air-conditioning compressor with control 42 NOX sensor 14 Diagnosis interface 43 Broadband oxygen sensor Type LSU 15 Glow plug control unit 44 NOX accumulator-type catalytic converter CAN Controller Area Network 45 Two-point oxygen sensor Type LSF (vehicle’s serial data bus) 46 Catalyzed soot filter Type CSF . etc. three alternative com- to understand the system. b and c). engine control unit and high-pressure C Fuel supply system (low-pressure system) fuel-injection components 16 Fuel filter with overflow valve 24 Fuel rail 17 Fuel tank with filter and electric presupply pump 25 Camshaft 18 Fuel level sensor 26 Unit injector 19 Fuel cooler 27 Glow plug 20 Pressure limiting valve 28 Diesel engine (DI) 29 Engine control unit (master) D Additive system 30 Engine control unit (slave) 21 Additive metering unit M Torque 22 Additive control unit 23 Additive tank A Sensors and desired-value generators 1 Accelerator-pedal sensor E Air-intake system 2 Clutch switch 31 Exhaust-gas recirculation cooler 3 Brake switches (2) 32 Charge-air pressure actuator 4 Operator unit for cruise control 33 Charge-air (in this case with variable 5 Glow plug/starter switch (“ignition switch”) turbine geometry) 6 Vehicle-speed sensor 34 Intake manifold flap 7 Crankshaft speed sensor (inductive) 35 Exhaust-gas recirculation actuator 8 Engine-temperature sensor (in coolant system) 36 Vacuum pump 9 Intake-air temperature sensor 10 Charge-air pressure sensor F Emission control systems 11 Hot-film air-mass flow sensor (intake air) 37 Exhaust temperature sensor 38 Oxidation catalytic converter B Interfaces 39 Particulate filter 12 Instrument cluster with signal output for fuel 40 Differential-pressure sensor consumption. Ex. 45 9 37 42 43 or 42 38 44 10 40 c 43. Robert Bosch GmbH Overview of discrete cylinder systems System diagram of UIS for cars 89 1 Diesel fuel-injection system for cars using unit injector system B 16 C D CAN 12 21 17 18 13 19 14 20 15 24 22 23 25 A 26 1 27 29 2 31 28 3 CAN M E 4 30 35 34 5 36 33 6 32 a 37 37 F 7 38 39 8 40 b 41 37 43. 45 37 42 43 or 42 æ NMK1821Y 11 46 44 . oil quality sensor. tacho- components may not be used. retarder. pressure section of the overall system. transmission control system. only tive combination systems are shown (a. cruise control. starter motor. three alterna- For the sake of clarity of the diagram.g. fan) 36 Pressure limiting valve 29 Diesel engine (DI) 30 Flame glow plug (alternatively grid heater) D Air intake system M Torque 37 Exhaust-gas recirculation cooler 38 Control flap A Sensors and setpoint generators 39 Exhaust-gas recirculation actuator with exhaust-gas 1 Accelerator-pedal sensor recirculation valve and position sensor 2 Clutch switch 40 Intercooler with bypass for cold starting 3 Brake switches (2) 41 Turbocharger (in this case with VTG) with 4 Engine brake switch position sensor 5 Parking brake switch 42 Charge-air pressure actuator 6 Control switch (e. engine speed and torque reduction) E Emission control systems 7 Starter switch (“ignition switch”) 43 Exhaust-gas temperature sensor 8 Charge-air speed sensor 44 Oxidation-type catalytic converter 9 Crankshaft speed sensor (inductive) 45 Differential-pressure sensor 10 Camshaft speed sensor 46 Particulate filter 11 Fuel temperature sensor 47 Soot sensor 12 Engine-temperature sensor (in coolant system) 48 Fluid level sensor 13 Charge-air temperature sensor 49 Reducing agent tank 14 Charge-air pressure sensor 50 Reducing agent pump 15 Fan speed sensor 51 Reducing agent injector 16 Air-filter differential-pressure sensor 52 NOX sensor 53 SCR catalytic converter B Interfaces 54 NH3 sensor 17 Air-conditioning compressor with control 55 Blocking catalytic converter 18 Alternator 56 Catalyzed soot filter Type CSF 19 Diagnosis interface 57 Hydrolyzing catalytic converter 20 SCR control unit . Figure 2 shows all the components of a unit Data exchange with a wide range of other injector system for a six-cylinder diesel com. the fuel-supply system. Fig. vehicle manage- The components of the electronic diesel ment system. brake co-ordinator. fleet man- control system EDC (sensors. They differ only in the high. some of the bility program ESP. b those sensors and desired-value generators and c). engine control unit and high-pressure CAN Controller Area Network (vehicle’s serial data bus) injection components (up to three data busses) 22 Unit pump and nozzle-and-holder assembly 23 Unit injector C Fuel supply system (low-pressure system) 24 Camshaft 31 Fuel pump 25 Rocker arm 32 Fuel filter with water-level and pressure sensors 26 Engine control unit 33 Control unit cooler 27 Relay 34 Fuel tank with filter 28 Auxiliary equipment (e.g. Robert Bosch GmbH 90 Overview of discrete cylinder systems System diagram of UIS/UPS for commercial vehicles System diagram of UIS/UPS whose true position is necessary in order to understand the system are shown in their for commercial vehicles fitted locations. radar ranging sensor. Depending on the traction control system TCS. interfaces and agement system) involving up to 30 control engine control unit). graph. exhaust flap 35 Fuel level sensor for engine brake. electronic sta- type of vehicle and application. mercial-vehicle engine. For exhaust-gas treatment. units is possible via the CAN bus in the air-intake system and exhaust-gas treatment “Interfaces” section. intermediate speed control. systems (e. be connected to the CAN bus. 2 21 Air compressor Engine. Even the alternator (18) are very similar in the unit injector and unit and the air-conditioning system (17) can pump systems.g. Robert Bosch GmbH Overview of discrete cylinder systems System diagram of UIS/UPS for commercial vehicles 91 2 Diesel fuel-injection system for commercial vehicles using unit injector or unit pump system B C CAN 31 32 22 17 24 33 or 34 18 G 35 25 19 23 24 36 20 26 21 A 27 1 28 2 37 30 3 29 38 4 D M 5 39 6 40 7 41 8 42 45 E 9 43 43 47 a 44 46 10 48 50 11 52 49 or 12 51 52 43 54 54 b 44 53 55 13 14 48 50 49 45 52 15 or 43 51 52 43 54 æ NMK1822Y 16 c 56 57 53 44 . wide range of applications (see above) The modular design of the common-rail high injection pressures (up to approx. Design Overview of common-rail system The demands placed on diesel-engine fuel. They incorporate a fast-switching solenoid puts of up to 30 kW/cylinder.8 l engines producing tors. This The engine control unit using the common- is made possible by separating the functions rail fuel-injection system is made up of four of pressure generation and fuel injection. 3. Design rail system is its ability to vary injection pressure and timing over a broad scale. control unit and actua- three-cylinder. railway locomotives and opened and closed. and valve by means of which the nozzle is heavy-duty trucks. and 30 kW (41 bhp) of power and 100 Nm the air-intake and exhaust-gas systems of torque. the common-rail injector injects fuel when- cantly higher level of adaptability to engine ever the solenoid valve is open.1.. rail. the nozzles and the direct injection (DI) is used in the following high-pressure fuel lines types of vehicle: the electronic control system EDC made cars ranging from economy models with up of the sensors. In addition. injection systems is the pressure-accumulator system known as common-rail fuel injection. high-pressure accu- fuel-injection system for diesel engines with mulator (fuel rail). operating conditions tem is becoming more and more integrated in the overall network of vehicle systems. .5 l/100 km (NETC) to luxury sedans gas recirculation). All the injectors are fed by a common fuel tem than cam-operated systems. diesel engines have even broken into role in increasing specific power output.9 l engines developing 180 kW (245 bhp) of power and Among the most important components of 560 Nm of torque the common-rail system are the injectors. system simplifies adaptation to individual 1. cleaner and more (230.600 bar) according to engine powerful. Robert Bosch GmbH 92 Overview of common-rail system Areas of application.600 bar) engine designs. faster switching times and injection phases (even extremely retarded greater adaptability of the injection pattern post-injection is possible) to engine operating conditions make diesel variation of injection pressure engines more economical. capability of multiple pre. subsystems (Figure 1): the low-pressure system comprising the Areas of application components of the fuel-supply system the high-pressure system consisting of the The pressure-accumulator common-rail high-pressure pump. light commercial vehicles with power out. The common-rail system offers a signifi. design on the part of the fuel-injection sys. with eight-cylinder.and post- Higher pressures. hence the name “common-rail fuel denced by its: injection”. emission control and exhaust- 3. In contrast with other solenoid-valve controlled fuel-injection systems. low- the luxury-car market. As The common-rail system thus plays a major a result. The main advantage of the common. each cylinder. ering fuel consumption and decreasing noise One of the most advanced of these fuel.. and with fuel consumption of (air intake. This enables the injec- ships with engines producing up to 200 tion cycle to be individually controlled for kW/cylinder. 0. the fuel-injection sys. as evi. variable injection timing injection systems are continually increasing. and exhaust emissions from diesel engines. The EDC electronic-control system Fuel injection controls the individual fuel-injection com. the fuel quan- the engine speed as it is driven by a system tity injected is proportional to the length of with a fixed transmission ratio. Robert Bosch GmbH Overview of common-rail system Method of operation 93 Method of operation Pressure is controlled by means of a pressure control valve and/or a controlled inlet on the In the common-rail pressure-accumulator high-pressure pump. Because of time that the solenoid valve is open and thus the almost uniform injection pattern. electronic engine control unit. The speed of the high- pressure pump is directly proportional to At a constant system pressure. The pressurized fuel is fuel-injection system. As that pressure jector nozzle by means of mechanical actua- is stored in the pressure accumulator. engine’s combustion chambers. jected-fuel quantity. it is tors. smaller and designed for a lower peak drive- system torque than conventional fuel-injection systems. the functions of pres. The nozzles inject the fuel directly into the ponents. the entirely independent of the engine or pump high-pressure pump can be significantly speed (time-based fuel-injection system). A nozzle consists A continuously operating high-pressure essentially of an injector nozzle and a fast- pump driven by the engine produces the switching solenoid valve that controls the in- desired injection pressure. sensors. held in the fuel rail ready for injection. interfaces Fuel supply Air-intake and (low-pressure system) exhaust-gas systems Engine 1 2 3 æ NMK1871E Signals Fig. 1 Structure of an engine control unit using common-rail fuel injection Electronic Diesel Control EDC: engine control unit. 1 High-pressure system Diesel fuel 1 High-pressure pump 2 Fuel rail 3 Nozzle . sure generation and fuel injection are separate. The solenoid valve is controlled by the largely independent of engine speed and in. They are supplied by short high-pressure fuel lines Pressure generation connected to the fuel rail. Control unit configuration As the engine control unit has only six out- The position-time system matches the start put stages for the nozzles. etc. vol- and convenience. they ensure that engine and the vehicle (see also the chapter the diesel engine has low consumption and “Electronic diesel control EDC”).g. ume balancing). there is also a ble to precisely meter fuel injection.g. Electronic immobilizer. They are linked via an internal high- camshaft sensors (time-based control). Robert Bosch GmbH 94 Overview of common-rail system Method of operation Control Basic functions With the aid of a range of sensors. climate-control system or the transmission- culation valve or the charge-air actuator. In addi. A diagnosis interface enables analysis of The extremely fast switching times de. Cruise control. the nozzles and the other actuators. engines with more of injection to the rotation of the engine than six cylinders require two engine control using the data from the crankshaft and units. Others can be dynamically allocated to one or other of the control units as situations demand (e. higher microcontroller processing capacity tion. Some examples are: coolant and fuel Control of exhaust-gas recirculation the mass of the air charge Charge-air pressure control the road speed of the vehicle. Integration of EDC in an overall network trol signals required for the high-pressure of vehicle systems also opens up a range of pump. the The basic functions involve the precise con- engine control unit records the accelerator. example. for control system). Some functions are permanently functions that can improve engine response allocated to a specific control unit (e. collected includes: the crankshaft angle of rotation Additional functions the camshaft speed Additional control functions perform the the fuel rail pressure tasks of reducing exhaust-gas emissions and the charge-air pressure fuel consumption or providing added safety the temperature of intake air. new possibilities (e. In this way. As a result. recording of sensor signals). trol of injection timing and quantity at the pedal position and the current status of the set pressure. engine and convenience. configuration. The control unit analyzes the input signals and calculates within a split second the con. data exchange with the The latter may include the exhaust-gas recir. stored system data when the vehicle is ser- manded of the nozzles are achieved with the viced. aid of optimized high-pressure solenoid valves and a special control method. The data smooth running characteristics. etc. .g. The speed CAN interface in a master-and-slave electronic diesel control EDC makes it possi. EDC offers the potential for additional available. In more recent SCR systems. as turbochargers with variable turbine geom. control units . CO and despite advances particulate emis- in internal sions. Such sys- engine de. Which of are dealt with in 3 High-pressure pump them will eventually be. tems demand sign. Exhaust-gas recirculation greater adaptability on the part of the fuel- Cars injection system will be necessary. The com- Exhaust-gas recirculation is an effective mon-rail system offers a broad range of pos- method of reducing NOX components in sibilities: exhaust gas. passing it through a hydrolyzing catalytic cial vehicle engines. then reduce not portant for diesel en. 4 components on a mercial vehicles. A version for use in car diesel Such engines do not generally have a nega. In combination systems (also called four-way Exhaust-gas treatment systems systems). control systems 2 Fuel rail velopment. The SCR (Selective Catalytic Reduction) let manifold downstream of the compressor catalytic converter reduces NOX emissions at high engine loads. additional features such converter. the hydrolyzing catalytic converter is inte- etry (VTG).g. Robert Bosch GmbH Overview of common-rail system Method of operation 95 Air-intake and exhaust-gas systems unanswered question. Commercial vehicles An NOX accumulator-type catalytic The vast majority of modern diesel engines converter reduces the nitrogen oxides NO are fitted with an exhaust-gas turbocharger. emission control will 1 bined. Ammonia is culation and cooling is essential even at the obtained from the reducing agent urea by higher end of the power curve on commer. more detail in a 4 Electronic engine come established remains an separate chapter. This is 3 very powerful particularly engine control Fig. It involves the use of a valve A diesel-oxidation catalytic converter which returns some of the exhaust gas to the (DOC) primarily reduces hydrocarbon intake manifold. tems are com- tion. and NO2. however. necessary. This method has been the state of volatile particulate components. Common-rail system cars and com. They can become increasingly im. engines is currently in the process of de- tive pressure differential between the exhaust velopment. If the recirculated exhaust (HC) and carbon monoxide (CO) emis- gas is also cooled. CRT (Continuous Regeneration Trap) system or an additive system). only NOX but 2 gines in the future also HC. manifold upstream of the turbine and the in. The most impor. further advantages can be sions as well as a proportion of the gained. Since exhaust-gas recir. Various types of particulate filter (PF) The exhaust gas is recirculated at low engine filter the soot particles from the exhaust loads and speeds. commercial-vehicle diesel engine There are many tant emission 1 Injector æ UMK1872Y systems under de. several In order to be able to comply with individual sys- stricter emission-control legisla. with the help of ammonia. As a rule. 2 true for larger units. gas (e. wastegate or flutter valve are grated in the SCR catalytic converter. the art for diesel cars for a number of years. the the electronic stability program ESP sensors and setpoint generators (A) are not shown in their fitted positions. as their proper fitted positions are necessary in order to understand the system. Depending on the the alternator type of vehicle and application. Fig. some of the the electronic immobilizer components may not be used. b and c). engine speed. Exceptions to Even the instrument cluster (12) and the air- this are the sensors of the exhaust-gas treat. 43 NOX accumulator-type catalytic converter 13 Air-conditioning compressor with control 44 Two-point oxygen sensor Type LSF 14 Diagnosis interface 45 Catalyzed soot filter Type CSF 15 Glow plug control unit CAN Controller Area Network (vehicle’s serial data bus) . the starter motor cylinder diesel car engine. For emission control. engine control unit and high-pressure C Fuel supply system (low-pressure system) fuel-injection components 17 Fuel filter with overflow valve 16 High-pressure pump 18 Fuel tank with filter and electric fuel pump 23 Engine control unit (master) 19 Fuel level sensor 24 Engine control unit (slave) 25 Fuel rail D Additive system 26 Fuel-rail pressure sensor 20 Additive metering unit 27 Injector 21 Additive control unit 28 Glow plug 22 Additive tank 29 Diesel engine (DI) M Torque E Air-intake system 30 Exhaust-gas recirculation cooler A Sensors and setpoint generators 31 Charge-air pressure actuator 1 Accelerator-pedal sensor 32 Turbocharger (in this case with variable 2 Clutch switch turbine geometry) 3 Brake switches (2) 33 Control flap 4 Operator unit for cruise control 34 Exhaust-gas recirculation actuator 5 Glow plug/starter switch (“ignition switch”) 35 Vacuum pump 6 Vehicle-speed sensor 7 Crankshaft speed sensor (inductive) F Emission control systems 8 Engine-temperature sensor (in coolant system) 36 Exhaust temperature sensor 9 Intake-air temperature sensor 37 Oxidation catalytic converter 10 Charge-air pressure sensor 38 Particulate filter 11 Hot-film air-mass flow sensor (intake air) 39 Differential-pressure sensor 40 Exhaust heater B Interfaces 41 NOX sensor 12 Instrument cluster with signal output for 42 Broadband oxygen sensor Type LSU fuel consumption. and For the sake of clarity of the diagram. the transmission control system the traction control system TCS. conditioning system (13) can be connected ment systems (F) and the fuel-rail pressure to the CAN bus. sensors. 3 Engine. three alternative combination systems are shown (a. etc. Robert Bosch GmbH 96 Overview of common-rail system System diagram for cars System diagram for cars The CAN bus in the interfaces section (B) enables exchange of data between a wide va- Figure 3 shows all the components of a fully riety of systems and components including equipped common-rail system for an eight. Robert Bosch GmbH Overview of common-rail system System diagram for cars 97 3 Common-rail diesel fuel-injection system for cars B 17 C D CAN 12 16 20 18 19 13 14 26 25 15 21 22 A 27 1 28 23 2 30 29 3 M CAN E 4 24 33 5 34 35 32 6 31 a 36 36 F 7 37 38 8 39 b 40 36 42. 44 36 41 42 or 41 æ NMK1819Y 11 45 43 . 44 9 36 41 42 or 41 37 43 10 c 39 42. b fitted locations. whose true position is necessary to the un. starter motor. For exhaust-gas treatment. agement system) involving up to 30 control some of the components may not be used.g. tacho- equipped common-rail system for a six-cylin. vehicle manage- der diesel commercial-vehicle engine. and c). radar sensor ACC. transmission control system. exhaust flap 27 Pressure limiting valve for engine brake. brake co-ordinator. Depend. retarder. three alterna- derstanding of the system are shown in their tive combination systems are shown (a. engine control unit and high-pressure CAN Controller Area Network (vehicle’s serial data bus) injection components (up to three data busses) 22 High-pressure pump 29 Electronic engine control unit C Fuel supply system (low-pressure system) 30 Fuel rail 23 Fuel pump 31 Fuel-rail pressure sensor 24 Fuel filter with water-level and pressure sensors 32 Fuel injector 25 Control unit cooler 33 Relay 26 Fuel tank with filter 34 Auxiliary equipment (e. 4 21 Air compressor Engine. ment system. cruise control. fan) 28 Fuel level sensor 35 Diesel engine (DI) 36 Flame glow plug (alternatively grid heater) D Air intake system M Torque 37 Exhaust-gas recirculation cooler 38 Control flap A Sensors and desired-value generators 39 Exhaust-gas recirculation actuator with exhaust 1 Accelerator-pedal sensor recirculation valve and position sensor 2 Clutch switch 40 Intercooler with bypass for cold starting 3 Brake switches (2) 41 Turbocharger (in this case with variable 4 Engine brake switch turbine geometry) with position sensor 5 Parking brake switch 42 Charge-air pressure actuator 6 Control switch (e. engine speed and torque reduction) E Exhaust-gas treatment systems 7 Starter switch (“ignition switch”) 43 Exhaust-gas temperature sensor 8 Charge-air speed sensor 44 Oxidation-type catalytic converter 9 Crankshaft speed sensor (inductive) 45 Differential-pressure sensor 10 Camshaft speed sensor 46 Particulate filter 11 Fuel temperature sensor 47 Soot sensor 12 Engine-temperature sensor (in coolant system) 48 Fluid level sensor 13 Charge-air temperature sensor 49 Reducing agent tank 14 Charge-air pressure sensor 50 Reducing agent pump 15 Fan speed sensor 51 Reducing agent injector 16 Air-filter differential-pressure sensor 52 NOX sensor 53 SCR catalytic converter B Interfaces 54 NH3 sensor 17 Air-conditioning compressor with control 55 Blocking catalytic converter 18 Alternator 56 Catalyzed soot filter Type CSF 19 Diagnosis interface 57 Hydrolyzing catalytic converter 20 SCR control unit . only (18) and the air-conditioning system (17) the sensors and desired-value generators can be connected to the CAN bus. units is possible via the CAN bus in the “Interfaces” section (B). fleet man- ing on the type of vehicle and application. Robert Bosch GmbH 98 Overview of common-rail system System diagram for commercial vehicles System diagram for Data exchange with a wide range of other systems (e. intermediate speed control. oil quality sensor. Even the alternator For the sake of clarity of the diagram. commercial vehicles traction control system TCS.g. graph. Fig.g. electronic sta- Figure 4 shows all the components of a fully bility program ESP. Robert Bosch GmbH Overview of common-rail system System diagram for commercial vehicles 99 4 Common-rail diesel fuel-injection system for commercial vehicles B 23 24 C CAN 17 22 27 25 28 26 18 G 19 20 31 30 29 21 A 32 1 33 34 2 37 3 36 35 38 4 39 M D 5 40 6 7 41 42 8 45 E 43 43 47 9 a 44 46 10 48 50 11 52 49 or 51 52 43 54 54 12 b 44 53 55 13 14 48 50 49 45 15 43 51 52 43 54 æ NMK1820Y 16 c 56 57 53 44 . It can form part of an chamber and the main combustion chamber. Due to the rapid improvement in microcon- As a result. Robert Bosch GmbH 100 Electronic diesel control EDC Requirements. overall electronic vehicle-control system the fuel consumption of direct-injection en. the in- variation of injected-fuel quantity. System overview Electronic diesel control EDC Electronic management of a diesel engine temperature-based variation of start enables precise and differentiated variation quantity of fuel-injection parameters. what was origi- injection pressures than indirect-injection nally a straightforward system using electric (IDI) engines with swirl or precombustion actuators has developed into the present-day chambers. Noise levels too are subject to more and more demanding expectations. the performance demanded of troller performance over recent years. jection quantity is determined by a number air pressure and start of injection to suit of variable factors. CO. diesel-engine development has been influenced by the high levels of comfort and convenience demanded in modern System overview cars. And as a result of increas- gines is 10 . the the fuel-injection and engine-management electronic diesel control EDC is capable of systems has also increased. the control-system circuitry can be accommodated in a very small space. EDC. par. system capable of processing large amounts lated losses between the swirl/precombustion of data in real time. Because of the more efficient mix. regard to In contrast with diesel-engined vehicles with conventional mechanically governed high injection pressures fuel-injection pumps. erating conditions and ensures high-quality ticulates) combined with simultaneous im. of mixture formation. in the popularity of the direct-injection (DI) diesel engine which uses much higher fuel. high precision over the service life of the system (long-term performance). Requirements Conventional mechanical governing of engine speed uses a number of adjusting The lowering of fuel consumption and mechanisms to adapt to different engine op- pollutant emissions (NOX. Instead. HC. “sensors and desired-value genera.. over the injected fuel quantity through the post-injection accelerator pedal and cable. As demands have increased. The EDC (Electronic Diesel cruise control. this has led to an increase cannot respond quickly enough to. where applicable. and Control) system is subdivided into three tight tolerances for start of injection and areas. (“drive by wire”). 20 % lower than that of indirect. “control unit” and “actuators”. ing integration of electronic components. injection designs.. specifically with meeting all the demands outlined above. a complex electronic engine-control ture preparation and the absence of flow-re. Nevertheless. the driver of a vehicle injection-pattern variability equipped with EDC has no direct control pre-injection and. variables that it cannot take account of or In recent years. They include: operating conditions . In addition. That is control of idle speed independently the only means by which a modern diesel of engine load engine is able to satisfy the many demands controlled exhaust-gas recirculation placed upon it. charge. injected-fuel quantity and maintenance of tors”. it is re- provement of engine power output and stricted to a simple engine-based control torque are the guiding principles of current loop and there are a number of important development work on diesel-engine design. Robert Bosch GmbH Electronic diesel control EDC System overview, System structure 101 the vehicle response desired by the driver System structure (accelerator-pedal position) the engine operating status Electronic diesel control EDC is subdivided the engine temperature into three sections (Figure 1): intervention by other systems (e.g. traction control) 1. The sensors and desired-value generators the effect on pollutant emission levels, etc. (1) detect the engine operating conditions (e.g. engine speed) and the driver’s control The control unit calculates the injected-fuel commands (e.g. switch positions). They quantity on the basis of all those factors. convert physical variables into electrical The start of injection can also be varied. signals. This demands a comprehensive monitoring concept that detects inconsistencies and ini- 2. The control unit (2) processes the infor- tiates appropriate actions in accordance with mation received from the sensors and de- the effects (e.g. torque limitation or emer- sired-value generators using specific mathe- gency mode in the idle-speed range). EDC matical calculation sequences (control algo- therefore incorporates a number of control rithms). It controls the actuators by means loops. of electrical output signals. It also provides interfaces with other systems (4) and with The Electronic Diesel Control system is the vehicle’s diagnostic system (5). also capable of data exchange with other electronic systems such as traction control, 3. The actuators (3) convert the electrical out- transmission control or dynamic handling put signals from the control unit into physical systems such as ESP (Electronic Stability variables (e.g. the solenoid valve for fuel in- Program). As a result, the engine control jection or the solenoid pump-actuator sole- unit can be integrated in the vehicle’s overall noid). control-system network, thereby enabling functions such as reduction of engine torque when the automatic transmission changes gear, regulation of engine torque to compen- 1 EDC system structure sate for wheel slip, enabling fuel injection by the engine immobilizer, etc. The EDC system is fully integrated in the vehicle’s diagnostic system. It meets all OBD 2 4 5 (On-Board Diagnosis) and EOBD (Euro- pean OBD) requirements. 1 3 Fig. 1 1 Sensors and desired-value generators (input signals) 2 Control unit æ UAE0734Y 3 Actuators 4 Interface with other systems 5 Diagnosis interface Robert Bosch GmbH 102 Electronic diesel control EDC Application-related adaptation of car engines Application-related data maps (e.g. injection point tE as a function of engine speed n, injected-fuel 1) Some parts of the adaptation1) of car engines quantity me and start of delivery FB). adaptation process are also referred to Application-related adaptation means modi- as calibration. fication of an engine to suit a particular type The optimization potential of EDC systems of vehicle intended for a specific type of use. has become so great that it is now limited Adaptation of the fuel-injection system – only by the constraints of time available and and specifically of electronic diesel control the cost of the personnel and the work in- EDC – is a major part of that process. volved in adapting and testing the various functions and their interaction. All new diesel engines for cars are now direct- injection (DI) engines. And they all have to Adaptation phases comply with the Euro III emission control Application-related adaptation of car en- standards that have been in force since 2000, or gines is subdivided into the three stages other comparable standards. These emission described below. standards – combined with the higher expectations in the area of vehicle user-friendliness – Hardware adaptation can only be met by the use of sophisticated In the context of application-related adapta- electronic control systems. Such systems have tion of car engines, items such as the com- the capability – and reflect the necessity – of bustion chamber, the injection pump and controlling thousands of parameters (approx. the injectors are referred to as hardware. 6,000 in the case of the present EDC genera- That hardware is primarily adapted in such tion). Those parameters are subdivided into: a way that the performance and emission individual parameter values figures demanded are obtained. Hardware (e.g. temperature thresholds at which adaptation is performed initially on an en- specific functions are activated) and gine test bench under static conditions. If ranges of parameter values in the form dynamic tests are possible on the test bench, of two-dimensional or multi-dimensional they are used to further optimize the engine and the fuel-injection system. 1 Vehicle-specific calibration using PC tools has become the standard æ SAE 0922Y Robert Bosch GmbH Electronic diesel control EDC Application-related adaptation of car engines 103 Software adaptation For example, at low engine loads a very high Once the hardware adaptation is complete, exhaust-gas recirculation rate is aimed at in the control-unit software is accordingly order to reduce the NOX emissions. Under configured and adapted for optimum mix- dynamic conditions, this can lead to poor ture preparation and combustion control. “accelerator response” on the part of the For example, this includes calculating and engine. In order to obtain good acceleration programming the engine data maps for start characteristics, the static emissions settings of injection, exhaust-gas recirculation and programmed in the software adaptation charge-air pressure. As with hardware adap- phase must be re-adjusted. In turn, this may tation, this work is carried out on the test result in negative effects on emissions under bench. certain engine operating conditions which have to be compensated for under other Vehicle-related adaptation conditions. When the basis for the initial vehicle trials has been established, adaptation of all para- In the example outlined, there is a funda- meters that affect engine response and dy- mental conflict between the various objec- namic characteristics takes place. This third tives: on the one hand, strict requirements stage involves the essential adaptation to the have to be met (e.g. statutory limits for ex- particular vehicle concerned. The work is for haust emission levels), while on the other the greater part performed with the engine hand there are “optional” demands that are in situ (Figure 1). more attributable to the desire for comfort and performance (engine response, noise, Interaction between the three phases etc.). The latter can result in opposing con- As there are reciprocal effects between the clusions. A compromise between the differ- adaptation phases, recursions (repeated pro- ent objectives offers the vehicle manufac- cedures) are required. As soon as possible, it turer the opportunity to imbue the vehicle is also necessary to run all three phases si- with some of the features that make up its multaneously with the engine in the vehicle characteristic brand identity. and on the test bench. 2 Stages in the calibration of a control function Abrupt response Amplitude and phase response Stability limit Excitation Input Output Measurement of system characteristics Frequency analyser System parameters Bode diagram Description of z sm +…+ zo G(s) = m n KRkrit, Tkrit system characteristics nn s +…+ no Ziegler/ Nichols Chien/ Hrones/ Amplitude Phase Ziegler/ Nichols (Tt, Ks, Ts) Reswick boundary method boundary method (KRkrit, Tkrit) æ SAE 0923Y Definition of controller parameters functions that require adaptation (e.g. a special communication code is employed (input and output variables). winter trials in would be destroyed by over-revving. there are several tudes with a cold engine. torque available at the driving wheels would be insufficient.g. in Spain’s Sierra Nevada or Such safety functions are primarily in- in the Alps). the glow ety of different ambient conditions. The EDC also provides adaptation functions for extreme ambient conditions. very specific adjustments ambient conditions have to be made to the injected fuel quantity The various controllers and adjustment pa. to prevent engine damage). the clutch is engaged or disengaged. as the there are as many as 50 parameter sets.g. At high alti- trol idle speed. plugs have to be switched on. passes (e. in the Alps) and emission levels. . To con. e. 3 Screen of an engine test-bench monitor (example) Communication There are also numerous functions which require communication between the engine control unit and other control units on the vehicle (e. additional measured data has to be calculated and encoded in the appropriate form.g. Altitude compensation for turbocharged erally have to be verified by specifically tar. transmission control for automatic transmission and electronic immobilizer). Sweden) hot-weather testing in temperatures over Other adjustments 40 °C (e. For which are further differentiated according some applications. For this reason. Robert Bosch GmbH 104 Electronic diesel control EDC Application-related adaptation of car engines Adaptation to differing For cold starting. for example. ESP. tended to restore the vehicle to a safe operating condition for the driver and/or to ensure the safe operation of the engine (e.g.g. and the start of delivery based on engine rameters must be configured for a wide vari. power output and user- combined hot-weather and altitude or friendliness. These gen. the effectively parameter sets for each individual gear available pull-away torque is very low. engines demands limitation of the required geted special trials involving turbocharger pressure in response to atmos- cold-weather testing in temperatures pheric pressure. traction control. re- towing a heavy trailer over mountain sponse to failure of a sensor or actuator). there are also numerous safety cold-weather and altitude testing. summer trials in Arizona) Safety functions high-altitude/low atmospheric pressure As well as the functions that determine testing (e. coolant temperature. In addition. Particularly in the case of vehicles with automatic transmission.g. as otherwise the turbocharger down to –25 °C (e.g. EDC suspends tur- to whether bocharger operation for that short period the vehicle is stationary or moving because it would otherwise “use up” a large the engine is warm or cold proportion of the engine’s torque output. vehicle from pulling away at all. this would prevent the That means that for this function alone. Where neces- æ SAE 0924Y sary. reliable protection of the engine against ex- This is followed by a comprehensive road cessive charge-air pressure and consequent test. Idle-speed control must function may attempt to even them out by al- operate with absolute reliability under all teration of the injected-fuel quantity volume possible engine operating conditions. The con- is idling and to a harder response when the trol function then has the task of maintaining engine is under load. for example. the charge-air pressure is controlled definition (i. optimum response characteristics (rapid gen- trolled system by algorithms and definition eration of charge-air pressure) while ensuring of the control parameters). for individual cylinders. this func- cially with regard to the interplay with the tion must be thoroughly tested under all oper- twin-mass flywheels generally used. is highly involved. conditions. The aim is to obtain system response. Depending on the This function controls the speed at which frequencies generated as a result of periodic the engine runs when the accelerator pedal speed fluctuations. In order to ensure smokeless and low- order to diminish the various conflicts in NOX combustion. all engine operating conditions. extensive adaptation work is required. even more unevenly. This ating conditions.e. power-steering pump. have cylinders and in so doing improves engine considerably expanded. A circular track (test track) provides the excessively high cylinder pressure. On most of those The first stage of the process is an analytical engines. conflict between objectives can Exhaust-gas recirculation EGR is now a stan- arise as this function may prevent rapid dard feature of DI car diesel engines. description of the con. the engine factor in the amount of air that enters the en- mountings also play an important part. the engine smooth-running is not depressed. together with the control in engine speed or load. air-conditioning com- Idle-speed control pressor) significantly alter. possibility for virtually unlimited flat-road driving. . Under unfavourable fore. conform to precisely defined parameters for ploy variable-characteristic engine mount. control functions) circumstances. alternator. Almost all existing DI car diesel engines are fitted with turbochargers. espe.g. type of flywheel produces highly complex rotational vibration effects throughout the Pressure-charging controller drivetrain. those parameters under dynamic operating conditions without adversely affecting the response characteristics of the engine. Particularly with active surge Exhaust-gas recirculation EGR damping. Those para- ings which are controlled by the EDC. The engine smooth-running function ensures the possibilities for optimization. drive systems for auxiliary units (e. therefore. some applications em.g. These meters are initially optimized under static can be set to a softer setting when the engine conditions on the engine test bench. For that reason. As pre- compensation in response to abrupt changes viously indicated. In gine. recording of the controlled by the EDC system. all of which have to be specifically high or very low ambient temperatures if the adapted to each individual vehicle. a malfunction can occur at very are used. of turbocharger pressure it is a determining Apart from the drivetrain. especially that the injection volumes are the same for all with regard to the convenience features. Under certain software functions (e. Some vibration damping characteristics of the belt examples are outlined below. There. Robert Bosch GmbH Electronic diesel control EDC Application-related adaptation of car engines 105 Examples of adaptation Smooth-running control Since the arrival of the EDC system in 1986. A wide variety of smoothness and emission levels. this may then result in higher ex- Adjustment of the coasting response in all haust-emission levels or make the engine run gears. the air-fuel mixture must objectives. the follow. Particularly because of its economy and into account. For that reason fuel consumption • curves. when ne. HC and CO emission and ex.g. etc. Other criteria: particulate. i. sure.e. Engine system gotiating steep gradients or using PTO drives). Yes pected to be able to complete over a million Emissions test Fig. OK? ✔ Smoothness. fuel-rail pres- on control unit in engine adaptation. objectives outlined above are achieved as fully as possible. Hardware adaptation 2) der to be able to move heavy loads in even Fuel-injection the most difficult situations (e. Today all new engines are direct-injec. OK? cles registered in the European Union have Vehicle-related Yes adaptation 4) 3) Additional criterion: been required to conform to the Euro III Vehicle. idle. altitude. that the best possible Optimization objectives compromise is reached between competing For commercial-vehicle engines. . engine response.g. Dynamic adaptation emission-control standard. new commercial vehi. demands. maximum permissible and combustion cylinder pressure and exhaust temperature) as well as the smoke emission limit have to No No OK? be taken into account. engine test bench • data maps. The aim of adaptation is to ensure that the tion (DI) designs. occupies a position of greater importance No • factors. and fuel-injection hardware components as Torque 1 Flow chart for engine adaptation process The aim is to obtain the maximum possible torque under all operating conditions in or. When pursuing that objective. cold start Full-load response Emissions Pollutant emissions No Fuel consumption Since October 2000. Minimizing fuel consumption (or CO2 Controller configuration. 1 kilometers of service. No Yes Starting characteristics haust opacity are reliably complied with. quietness. the diesel has established itself as the engine of choice for commercial vehi. smoothness and adaptation process are also referred to vehicle engines starting characteristics must also be taken as calibration. Robert Bosch GmbH 106 Electronic diesel control EDC Application-related adaptation of commercial-vehicle engines Application-related Comfort/convenience The demands relating to such aspects as 1) Some parts of the adaptation1) of commercial. Engine adapta. Yes cars. sive factor. durability. This involves adaptation of engine ing attributes are optimized. dynamic) 2) Criteria: warm start. summer and winter trials æ SAE0925E 4) tion must ensure that the limits for NOX. emissions) is therefore of prime significance start of injection. Adaptation phases cles. economy is a deci. etc. exhaust-gas recirculation No Durability OK? Modern commercial-vehicle engines are ex. (static. the Mixture formation engine’s limits (e. Software adaptation 3) Yes Fuel consumption Adaptation of Calibration on For commercial vehicles. OK? for commercial vehicles than is the case with • switches. Robert Bosch GmbH Electronic diesel control EDC Application-related adaptation of commercial-vehicle engines 107 well as software functions performed by the components) and. if necessary. Because of the ever increasing number of Specification by remote such parameters. engine. the control-unit software is configured ac- cant engine-hardware components include cordingly. curve injection pressure. the turbocharger. the exhaust- engine-management module. of the fuel-injection system are the injection ware. Signifi. Hardware adaptation Hardware adaptation involves making modi. if applicable. etc. atmospheric pressure.). fuel consumption. tionships between a vast number of engine the air-intake system (e. ble. and the injectors. the appropriate parameter values. for dynamic conditions data curves and data maps are then calculated and programmed (Figure 3 overleaf). Significant components As with car engines. software and vehicle-related adapta. Remote- control Fig. Stored in the software are the rela- the combustion chamber. bypass data maps coolant temperature and fuel temperature during calibration . data map activation point activation point under static operating conditions Control function configuration Adjustment Calibration of compensation data maps Basic activa. recirculation system. exhaust-gas recirculation. temperature speed quantity The following tasks are performed in the course of software adaptation: Start quantity Basic data map. the phases of hard. Software adaptation fications to all significant “components” of Once the hardware adaptation is complete. provides access to the software injected fuel to be adapted. 2 æ SAE0926E Following adaptation of the basic data maps. which – as with the adaptation of car engines – is linked to a PC with oper- Coolant Engine Specified ator software. automation of parameter control 5) configuration is a continuing aim. Compensation Calibration of the basic engine-data maps data map.g. see Figure 2). Hardware adaptation is carried out on the engine test bench. An application 2 Schematic diagram for timing of main-injection phase control unit. This work too is carried out on the engine test bench. the engine and fuel-injection system. 5) switch Specification of set the effect of such variables as ambient tem. pump. Based on those conditions Adjustment results. values in order to Activation point perature. swirl-imparting and fuel-injection parameters (for examples. pre- and post-injection – are carried out under Starting signal static operating conditions on the engine test bench. adjustments to the system-spe- Adjustment cific parameters – such as start of injection. The test results are assessed with reference to the target criteria (emission lev- Activation point under static els. Starter switch charge-air pressure and. for engine Optimisation of engine-data maps under tion point temperature dynamic conditions First of all. the high-pressure fuel lines if application can be distinguished (Figure 1). This en- ating conditions is finally optimized under sures good pulling away and manoeuvring dynamic conditions. charge-air pressure con. the control function engine for long-distance operation would be parameters can be adapted to the require- designed more for reliable and economical ments of the driven machine. When higher operating speed that is unaffected by adapting an engine for use in a bus. Robert Bosch GmbH 108 Electronic diesel control EDC Application-related adaptation of commercial-vehicle engines on the major parameters is factored into so. that are used to drive cranes. lifting plat- formed in the same way as for cars. used. response and minimal undershoot. engine response Many commercial vehicles have PTO drives and starting characteristics is essentially per. pumps. Vehicle-related adaptation The behavior of the drivetrain as a con- The process of vehicle-related adaptation trolled system depends heavily on tempera- involves modifying the basic design of the ture and transmission ratio.g. for ex. to the particular type of application. whereas a truck function. capabilities even when carrying heavy loads. Idle-speed control existing control functions are adapted (e. more emphasis is placed on comfort tem using the “intermediate-speed control” aspects or low noise output. major injection systems. The data established under static oper. load. Examples of adaptation called compensation data maps. When defining those parameters. etc. emphasis is generally placed on good load trol). changes ments under as wide a range as possible of in the drivetrain response over its service life real operating and ambient conditions. When adapting the idle-speed control func- fuel-rail pressure control for common-rail tion for a commercial-vehicle engine. though forms. must also be taken into account. and testing conformity with require. In addition. For that reason engine arrived at on the test bench to the the engine-management module has multi- specifics of the vehicle in which it is to be ple parameter sets for idle-speed control. 3 Data maps for start of injection and smoke limitation Start of injection Smoke limitation Advanced Maximum permissible injected-fuel quantity Retarded Inje cte Cha n d-fu rge. The adaptation/testing of the basic functions Power take-off (PTO) drives such as idle-speed control. Once again. These often require the the assessment criteria may differ according diesel engine to run at a virtually constant. ed dn air p pe æ SAE0927E el ee es qua ntit ine sp ress ure gin yQ Eng pL En . transportation of heavy loads. This can be governed by the EDC sys- ample. GPS navigation sys. maximum speed only able through control-unit configuration. transmission.e. control units and sensors concerned. the way in which tems and the wide use of other electronic 6) Control function accelerator-pedal position is translated into communications equipment (e. and on the other. The exchange of cable runs. Reliable diagnosis of faults ensures A typical example of the interaction between maximum possible vehicle availability. length of electronic control units. tems) in commercial vehicles make it neces. cuits to ground or to battery voltage. Robert Bosch GmbH Electronic diesel control EDC Application-related adaptation of commercial-vehicle engines 109 Engine response characteristics Electromagnetic compatibility In the process of adaptation. testing and. EMC room is absolutely essential. Once the operation is complete. detected faults have to be stored in a fault memory in order that service technicians can quickly locate and remedy the problem. a large proportion of this optimization work Communication is carried out during the development of the The EDC control unit on a commercial vehi. are to a large extent infinitely vari. The engine control unit constantly checks sion. brake the wiring looms in the actual vehicle has a and engine control units takes place via an major influence on immunity to and creation electronic data bus (usually a CAN). engine re. hot or cold weather. defined by the application developer. short cir- the gear-shifting operation. two-way radios. or a mixture of the two. 7) Variable-speed or ultimately depends on the application as to bility (EMC) of the engine-management incremental control whether an “RQ characteristic6)” or “RQV module and all its connecting leads in terms function characteristic7)” engine response is pro. type of shielding) and routing of data between vehicle.g. sufficiently narrow trol over the injected fuel quantity is passed to provide adequate sensitivity to real faults. The engine con. . Since. The signal – without input from the driver – thus en. As with engage the current gear. con. maximum speed or output. two vehicle control units is the process of changing gear with an automatic transmis. Of course. if necessary.g. fault response procedures must be defined which specify whether and in what way the engine may continue to be operated if a specific fault is detected. point to facilitate engagement of the new high altitudes) do not produce false diag- gear. the car engines. If necessary. The large number of electronic vehicle sys- sponse characteristics. mized until they are installed in the vehicle. It sary to optimize the electromagnetic compati. of emission of interference signals. commercial-vehicle systems are also very extensive. i. Finally. both of immunity to external interference and grammed. the dimensioning (e. Correct of interference.g. range limits and plausibility criteria must be abling the transmission control unit to dis. cle is normally part of a network of multiple however. noses. back to the driver. The transmission control unit sends that the signals from all connected sensors a request via the data bus for a reduction in and actuators are within the specified limits injection quantity at the optimum point in and also tests for loose contacts. radio tele- for minimum and injected-fuel quantity and engine torque phones. as the process of basic configuration on the Fault diagnosis engine test bench usually involves only the The diagnostic capabilities demanded of engine-management module on its own. those limits must on the one transmission control unit may request an hand be sufficiently broad to ensure that ex- increase in engine speed at the appropriate treme conditions (e. and for trol unit then makes the requested reduction plausibility with other signals. In addition. opti- interaction between the various control units mization of the complete vehicle inside an involved cannot be fully tested and opti. (e.g. The test-bench computer (20) is responsible 5 Fuel take air. 14 Control and sensor traveling downhill). 25 24 21 20 particle counter) 23 Dilution tunnel 26 30 24 Dilution air 25 Mixing section 29 27 26 Volume meter 27 Fan æ SWT0076Y 30 28 Particle sampling system 29 CVS bag system 30 Changeover valve . With the aid of system automation software. 6 3 opacimeter. Using appropriate simula- signals 15 Catalytic converter 16 Power supply 17 Measuring-data Basic layout of an engine test bench interface 18 Electric dynamometer 19 Accelerator 8 17 10 11 positioner 1 20 Test-bench computer 2 14 21 Indexing system 3 4 12 13 16 19 18 (rapid synchronized 7 9 measured-data 15 acquisition) 5 3 22 Exhaust-gas analyzing equipment (e. 10 Engine control unit load and engine-speed changes are increas- (EDC) 11 Intercooler ingly demanded. the testing equipment. for controlling and monitoring the engine and 6 Coolant 7 Heater ling their temperature and/or pressure) repro. in order to simulate overrun when This increases test-bench capacity utilization. dynamic tests with rapid out very efficiently. data recording and storage. (i. mass spectrometer. the engine in situ. calibration operations 9 Transfer modules In addition to measurements under static op. fuel and engine coolant. Fourier Transformed Infra-Red (FTIR) 28 22 23 spectroscope. Robert Bosch GmbH 110 Electronic diesel control EDC Engine test bench Engine test bench A fuel-injection system is tested on an engine tion software.g. data-map measurements) can be carried for supply fluids erating conditions. For such purposes there are Using a suitable quick-change system (8).e. pallets with the engines to be tested can be system They can not only retard but also drive the test changed over within about twenty minutes. control. It also takes care of 8 Quick-change ducible results can be obtained. 13 Engine vehicle (e. analyzers for gaseous emissions. the 12 Fuel-injection test benches with electric dynamometers (18). 3 Cold-water inlet 4 Hot-water inlet By conditioning the supply fluids such as in. the statutory emission control test bench as part of its development process.g. tests can then be run on the test bench rather 1 Intake air Engine test benches are designed to allow than on a vehicle tester with 2 Filter easy access to the various parts of the engine. ment and adjustment functions. A large part of the adaptation work. One such calibration tool The traditional calibration tools (for car and is the INCA (Integrated Calibration and commercial-vehicle applications) include Acquisition System) program. of a typical calibration process. stress. can be illustrated by the description below ware components is also becoming increas. The use and function of the calibration tools Computer simulation of hardware and soft. the engine test bench The Offline Tools (standard specification) the EMC room. is carried out using PC- based calibration tools. ing a number of different tools. ingly important. 1 a Thermo-Scan Interface module for temperature sensors b Dual-Scan Interface module for analog signals and temperature sensors f d e c Lambda Meter Interface module for broadband oxygen sensor d Baro-Scan Testing module for pressures e AD-Scan Interface module for analog signals f CAN-link card æ SAE 0928Y g g KIC 2 Calibration module for diagnostic interface . Such programs allow 1 Hardware for use with INCA calibration tool a b c Fig. and comprise the software for analysis of mea- a wide variety of special devices such as sured data and management of adjust- microphones for measuring sound levels ment data. however. and the programming tool for or strain gauges for measuring mechanical the Flash EPROM. It is made cylinder engine which has small windows up of the following components: and mirrors that allow the combustion The Core System incorporates all measure- process to be observed). Robert Bosch GmbH Electronic diesel control EDC Calibration tools 111 Calibration tools developers to modify the engine-management software. compromis- the “transparent” engine (usually a single. The aim of calibration is to alter the characteristics Preparations of the engine so that those requirements are met. exhaust composition) characteristics are defined by the engine manufacturer and the (exhaust emissions) legislation. measured data The measured data can not only be viewed after the measurements have been taken but while measurement is still in progress. Compared with the control units used on the production models. tem- Adjustment of various perature sensors.g. engine starting). Robert Bosch GmbH 112 Electronic diesel control EDC Calibration tools 2 Stages of calibration process Software calibration process Defining the desired characteristics The desired characteristics (e. noise output. flow meters) enables the parameters recording of other physical variables for special tests. An important aspect of the preparations is choos- ing and setting up the appropriate hardware and/or software interface. control units æ SAE 0929E Clearance for volume production .g. Additional measuring equipment (e. dynamic re- Definition of desired sponse. Documentation of modified In that way. they allow the alteration of parameters Identification of possibilities for manipulation that are fixed for normal operation. Establishment and documentation Preparations of actual system responses Special electronic engine control units are used for calibration. The data can also be recorded for subsequent analysis of tran- Programming of additional sient processes (e. The information concerned can be displayed on the screen and analyzed in the form of nu- Analysis of merical values or graphs.g. This necessitates testing on the engine test bench and in the vehicle. the response of the engine to parameters changes (e. in the exhaust-gas recirculation rate) can be investigated. Establishing and documenting the actual Observation system responses of changes The recording of specific measured data is carried out using the INCA core system.g. Robert Bosch GmbH Electronic diesel control EDC Calibration tools 113 Identifying possibilities for manipulation Documentation is important because several With the help of the control-unit software people will be involved in the process of en- documentation (data framework) it is possi. This necessitates re- processes (e. recorded during the course of a test. a single data record. This is done Alteration of selected parameters with the offline tool ADM (Application The parameters stored in the control-unit Data Manager). In such INCA core system tool PROF (Program- cases. ues (in tables) or as graphs (curves) on the The calibration data obtained by various PC and altered. the system response is observed. All parameters can be altered while the Programming additional control units engine is running so that the effects are The new parameter settings arrived at can immediately observable and measurable. Such documentation æ SAE 0930Y encompasses improvements as well as problems and malfunctions. Analyzing measured data 3 Software calibration screen (example) Analysis and documentation of the measured data is performed with the aid of the offline tool MDA (Measured Data Analyzer). ing of the steps described above may take Further tests are performed in order to place. . This is carried out using the while the process is in progress. This stage of the calibration process involves com- paring and documenting the system behavior before and after alteration of parameters. the measured data saved in a file and then the Depending on the extent of the calibration parameters that are to be altered identified and the design innovations. The changes to the parameters are also compared and documented. engine starting) it is effec. gine optimization at different times. sometimes also called CDM software can be displayed as numerical val. Each time an alteration is technicians is compared and merged into made. programming of the Flash EPROMs of those tively impossible to alter the parameters control units. evaluate the success of the adjustments made or to learn more about the process.g. therefore. the process has to be ming of Flash EPROM). multiple loop- by analyzing the recorded data. (Calibration Data Manager). also be used on other engine control units In the case of short-lived or transient for further calibration. ble to identify which parameters are best suited to altering system behavior in the Documenting the modified parameters manner desired. thermore. it is imperative that the EDC functions be precisely matched to every vehicle Data processing (DP) and every engine (Fig. The final results are not checked The required degree of accuracy together (open control loop). enough. The “Common Rail” accumulator “Electronic Control Unit” has become so fuel-injection system also controls injection widespread that it is still used even though pressure. characteristic maps. The stance. the micro- quantities processor calculates injection timing and its duration. detected.g. Fur- from outside are detected and taken into ac. EGR positioner. This information is then con- Open-loop control verted to a signal characteristic which is syn- With open-loop control. or boost-pressure ac- closed control loop. one or more input Using these input data. and algorithms. ators. Here. “ECU software”. Furthermore. the actuators are chronized the engine’s piston movements. The ECU processes the incoming signals from the external sensors and limits them Open. for in. The output signals are applied to output stages which provide adequate Closed-loop control power for the actuators (for instance. engine ECU monitors the complete fuel- injection system within the framework of a safety concept. the On the other hand. systems in the vehicle via the interfaces. on all systems. The advantage of closed. Robert Bosch GmbH 114 Open. triggered by the output signals which the This calculation program is termed the ECU has calculated using input variables. the actual value at tuator). Faulty signal characteristics are detected by loop control lies in the fact that disturbances the output-stage diagnosis functions. puting power. as its name implies.and closed-loop electronic control Data processing (DP) Open. to control the engine’s idle speed.and of the injected-fuel quantity and the start of closed-loop control unit”. and as soon as a deviation is relay and air conditioner) are triggered. namic response necessitate high-level com- trol. Closed-loop control is used. stipulated data. A number control of the incoming signals are also checked for plausibility. Apart from this. therefore. In fact. the the word “control” alone is not explicit engine ECU also controls a number of actu. . The term ECU injection. This principle is used with the diesel engine’s outstanding dy- for instance for the glow-plug sequence con. this is corrected by a change in the actuator control. glow desired value. signals are exchanged with other count. high-pressure solenoid valves for fuel injec- closed-loop control is characterized by a tion.and closed-loop to the permissible voltage level. the EDC Electronic tronic Diesel Control (EDC) is the control Control Unit (ECU) is really an “open. together with quantities influence one or more output stored characteristic curves. a number of other the output is continually checked against the auxiliary-function components (e.and closed-loop electronic control The most important assignment of Elec. 1). In both forms of control. For all components to operate eff- ciently. .. . .Continuous-operation braking system Fuel .. .Supercharging..Traction Control System (TCS). . Robert Bosch GmbH Open.In-line injection pumps.Climate control .Nozzles and nozzle holders. . injection components .Distributor injection pumps.Cruise Control (CC)..Fans. .Electropneumatic transducer .. Triggering of the fuel.and closed-loop electronic control Data processing (DP) 115 1 Electronic Diesel Control (EDC): Basic sequence Fuel control loop 1 (fuel-injection components) Air control loop Fuel control loop 2 (engine) Data and information flow “Detour” by way of the driver EDC ECU Exchange of data with other systems . . CAN Closed-loop control Closed-loop control of the fuel-injection system and triggering of the remaining actuators Demands from Sensors and desired- the driver value generators ..Switches . . .Rotational-speed sensor..Transmission-shift control.Accelerator-pedal sensor.Common Rail high-pressure pump and injectors. .Exhaust brake . Air Actuators . æ NMK1793E ..Unit Injector / Unit Pump. blowers.Driver input.Glow control . .Exhaust-gas recirculation (EGR). Engine System for electronic cylinder-charge control . Fuel-injection components . valve which cuts off the air supply when turned to the intake manifold in order to the engine is switched off. The degree of swirl is controlled by means of a swirl valve actuator which operates a flap or valve near to the inlet valve. Swirl is generally 4 Turbocharger induced by means of spiral-shaped intake æ UMK1551-9Y 5 Bypass valve 1 2 ports. position of the degree at high speeds. The control flap operated by an electro- In future.g. pneumatically controlled intake shut-off a proportion of the exhaust-gas flow is re. 3 8 4 Fig. 1 Swirl valve actuator 1 Wastegate actuator The swirl control function on car engines 5 2 Vacuum pump controls the swirling motion of the intake 3 Pressure actuator air inside the cylinder. 9 Systems with variable turbine geometry (VTG) turbochargers also adjust the tur. range. electric valves will also be used. the charge-air pressure control function operates a wastegate actuator which uses an electropneumatic bypass valve (the Charge-air pressure control using wastegate 1 wastegate) to divert a certain amount of the actuator exhaust-gas flow away from the turbocharger turbine (Figure 1). pneumatic valve on a diesel engine has an entirely different function from the throttle Wastegate actuator valve of a gasoline engine – it is used to in- The turbocharger is designed to deliver a crease the exhaust-gas recirculation rate by high charge-air pressure even at low engine lowering pressure in the intake manifold. 7 bocharger output. an electric or electropneumatic valve alters the angle of the deflector blades in the turbocharger inlet 6 channel. a connection between the exhaust manifold and the intake manifold controls the Control flap (throttle valve) amount of exhaust gas that is recirculated. amount of air being compressed and the An electropneumatic valve that provides engine cuts out more smoothly. As a rule. Swirl is a determining factor in the 6 Exhaust-gas flow 7 Intake air flow efficiency with which the fuel and air are 8 Turbine mixed in the combustion chamber and 9 Compressor therefore has a major effect on the quality of . Robert Bosch GmbH 116 Actuators Electropneumatic converters Actuators Actuators are the devices which convert the combustion. exhaust-gas recirculation valve or the control flap). a large degree of swirl electric output signals from the control unit is induced at low engine speeds and a lesser into physical quantities (e. In such cases. Thus. speeds in order to enable high engine-torque The control flap control function is only output right from the lower end of the speed active at low engine loads and speeds. This reduces the reduce the level of pollutant emissions. in order to prevent the charge- air pressure rising to excessive levels at high speeds. Electropneumatic converters Intake shut-off valve Exhaust-gas recirculation valve UIS systems for cars incorporate an electro- On a vehicle with exhaust-gas recirculation. kinetic energy is converted into heat and is tardation on long descents as the heat gener. . The engine control unit switches the radia- ally only air) to be expelled by the engine tor fan on and off as required according to through the exhaust system. The actuating fluid is engine oil. trollable electromagnetic field created by the power supply from the battery. This Fan control function makes it more difficult for the “exhaust” (because the fuel has been shut off it is actu. but static. The resulting air the temperature of the engine coolant. As a con. This cushion inside the cylinder slows down the is done by means of an electromagnetic piston during the compression and exhaust clutch. tion. There are two types as described below. sequence. the friction brakes are used significantly less and so remain cool and fully ef. The braking effect is infi- haust brake) is switched on. bladed component (the stator) facing oppo- mercial vehicles are non-wearing systems site it. The con. Braking systems of this type for heavy com. the fuel-injec. they offer Supplementary engine brake greater scope with regard to choice of loca- When the engine needs to be braked. continuous oil flow while the stator slows it down. The resulting Engine brake eddy currents retard the disk and therefore When the engine brake (also called an ex. The rotor is mechanically linked to that can reduce the speed of the vehicle – the vehicle’s drivetrain. are filled with oil. The braking systems are primarily suited to re. The engine brake is not capable of Electric fans are also increasingly em- graduated application – it is either on or off. In contrast is operated. The brak- ated can still be effectively dissipated in the ing effect is infinitely variable by controlling course of long periods of braking. trohydraulically operated valve-actuating device opens the exhaust valve at the end of the compression stroke. When the retarder but not bring it to a standstill. This type of retarder consists of an air- tinuous braking systems are controlled by cooled soft-iron disk that rotates in a con- the engine management module. The cylinder pressure is thus released and energy is lost from the system. Robert Bosch GmbH Actuators Continuous-operation braking systems. strokes. It is fitted to the drivetrain between the gearbox and the wheels and is therefore effective even when the drive between engine and gearbox is disengaged. As they do not have to be driven by a belt running off an engine pulley. Retarder A retarder is a continuous braking device that is independent of the engine. an elec. The rotor accelerates the tion brakes on the road wheels. Electrodynamic retarder fective if needed in an emergency. the quantity of oil in the retarder. Fan control function 117 Continuous-operation Hydrodynamic retarder This type of retarder consists of a rotating braking systems turbine (the rotor) and a similar. the road wheels. nitely variable. ployed. dissipated by the engine coolant. the rotor and stator chambers with service-brake systems which use fric. tion system cuts off the fuel supply to the engine and an electropneumatic valve moves a slide valve or a flap in the exhaust pipe. Item 3). That is why a warm diesel glow plug element and mixes with the intake engine will start spontaneously and a direct. and the by burning fuel in the intake port. On smaller in the air intake system on and off. direct-injection engines (up to 1l/cylinder). Whereas the heating is usually fed to the flame glow plug by the filament has an electrical impedance that is fuel-injection system’s injection pump via virtually independent of temperature. the a solenoid valve. En- gines with precombustion or swirl chambers Electric heater (grid heater) have a glow plug in the precombustion/swirl A relay switches a series of heater elements chamber to initiate combustion. vice which is set to allow a specific amount 1 Type GSK2 sheathed-element glow plug 1 2 3 4 5 6 7 Fig.000 °C. The fuel control filament (5). Intake-air preheating system That filament is made up of two resistors Flame glow plug connected in series – the heating filament A flame glow plug heats up the intake air (7) located in the tip of the sheath. The amount of heat is achieved with the engine turning at start. It consists of a hot-gas more easily combustible fuel for starting and corrosion-resistant element sheath (4) which is injected into the intake system. air. The passes over the glow-plug element that is spontaneous ignition temperature of 250 °C heated to over 1. ing inside a vapourizing tube around the ily combustible. there is a filter and a metering de. The fuel-and-air mixture then ignites at injection (DI) model will do so even when the front end of the flame glow plug as it started from cold at temperatures ≥ 0 °C. while direct-injection engines only bustion inside the cylinder. Large direct-injection engines for The element of the glow plug is permanently commercial-vehicles sometimes also have an sealed inside the gas-tight glow plug body intake-air preheating system or use a special (Figure 1. need help at temperatures below 0 °C. The fuel vaporiz- Compared with petrol. 1 1 Connector 2 Insulating washer 3 Glow-plug body 4 Element sheath 5 Control filament æ UMS0685-2Y 6 Packing powder 7 Heating filament 10 9 8 1 cm 8 Element seal 9 Double seal 10 Threaded collar . coefficient (PTC). which encloses a filament surrounded by compressed magnesium oxide powder (6). In the union of the flame control filament has a positive temperature glow plug. it is placed at the edge of the combustion Glow plug chamber. Robert Bosch GmbH 118 Actuators Start-assist systems Start-assist systems of fuel to pass through as required by the engine in which it is fitted. diesel fuel is very eas. produced is limited by the fact that the heating speed. Indirect-injection (IDI) engines ing flame is only allowed to burn a certain always require assistance when starting from proportion of the oxygen required for com- cold. thereby reducing smoke the older designs (Type S-RSK). This post-glow func. 4 To battery 1 æ UMS0691-2Y 5 Indicator lamp Operating sequence 6 Control line to The glow plug and starting sequence is engine management (in similar fashion to a gasoline engine) module governed by the glow-plug/starter switch 7 Diagnosis lead (“ignition switch”). A Type GZS glow plug control unit controls the glow plugs via a power relay. The fault is then 3 Glow-plug/ indicated to the driver. Fig. 3 ing phase begins when the key is turned to 3 Typical glow-plug sequence 1 Glow-plug/ the “Ignition On” position (Figure 3). safety cut-out for the glow-plugs prevents perature is kept below the critical level for the battery from discharging. Robert Bosch GmbH Actuators Start-assist systems 119 In the latest generation of glow plugs (Type A post-glow phase after the engine has GSK2). (“ignition switch”) 2 Starter ment cluster goes out. This means that the tem. 1 Glow-plug 2 3 tions. It receives its starting signal from the engine management module or a temperature sensor. tronic Diesel Control). The new emission and combustion noise while the Type GSK2 glow plugs are faster at reaching engine is below normal operating tempera- the temperature required for ignition ture. The glow-plug preheat. its impedance increases even more started helps to prevent misfiring during the steeply as the temperature rises than with warm-up phase. In the 4 Load switch subsequent starting phase. for any reason. droplets of in. ent engine operating conditions. the latter can use the tion results in a more effective engine warm. the glow plugs are hot 1 3 Indicator lamp enough for the engine to be started. 2 EDC controlled glow-plug system on direct-injection diesel engine The glow-plug control unit controls how long the glow plugs remain switched on and Fig. Consequently. 2 also performs safety and monitoring func. the engine is not (850 °C in 4 s) and also have a lower steady. information at its disposal to effect opti- up phase with substantially lower noise and mum control of the glow plugs under differ- emission output. it can remain If the glow-plug control unit is linked in operation for up to three minutes after with the control unit for the EDC (Elec- the engine has started. independently 4 æ UMS0667-2E τV Glow-plug tV tS tN preheating phase 5 τS Engine ready for 6 Time t starting τN Post-glow phase . 3 6 Point from which leased further assists in the propagation of engine runs combustion. When starter switch the glow-plug indicator lamp on the instru. 2 5 Glow-plug ON jected fuel vaporize and ignite on contact period with the hot. a state temperature. This provides a further means of minimizing blue Glow-plug control unit smoke and noise emission. started after the ignition is switched on. compressed air. If. The heat re. Advanced glow-plug control units can 2 Glow-plug control use the diagnosis functions to detect failure unit 4 5 of individual glow plugs. The control signal starter switch 6 7 (“ignition switch”) inputs are in the form of multi-connectors. the glow plug. combined with the minimum of component stant pulsating mechanical and thermal diversity. injection duration and termining factor in the efficiency of mixture rate-of-discharge curve (injection pattern) are formation and combustion and therefore the essential determinants of injected fuel has a fundamental effect on engine perfor. The nozzles are opened by the fuel pressure. The nozzle plays a major role in the geometry of the combustion chamber shaping the rate-of-discharge curve (pre. The nozzle must be designed specifically The nozzle is a central component of any for the type of engine in which it is used as fuel-injection system. When the engine is overrun. the required penetration and atomization tribution relative to crankshaft rotation) of the fuel jet optimum atomization and distribution the required injection duration. when no fuel is being injected. the nozzle is subjected to con. the nozzle is com- UP bined with the nozzle holder to form the nozzle-and-holder assembly (Figure 1) and UI installed in the engine. they have to be mum combustion pressure in order to prevent designed to match the fuel-injection system unwanted post-injection or intrusion of com- and engine in which they are used. In high-pressure fuel-injection systems such as the common Nozzle holder rail (CR) and unit injector systems (UIS) the nozzle is a single integrated unit so that the Nozzle nozzle holder is not required. the required injection-jet shape and direction cise progression of pressure and fuel dis. tion (and therefore hole-type nozzles). all new engine designs use direct injec- must also cool it. In reliably when the fuel pressure drops. quantity. it 1 The nozzle as the interface between fuel-injection system and diesel engine must have sufficient high-temperature resistance to cope with these conditions. It requires highly spe. the nozzle temperature increases steeply. PE In fuel-injection systems based on in-line injection pumps (Type PE) and distributor VE/VR injection pumps (Type VE/VR). determined by cialized technical knowledge on the part of the injection method (direct or indirect) its designers. The nozzles must close rapidly and mance. The clos- order that nozzles can perform their func. The fuel flowing through the nozzle offers. and in unit CR pump systems (UPS). Standardized dimensions and combinations Because of its exposed position in the combus. provide the required degree of adaptability tion chamber. and of fuel in the combustion chamber. It is a de. . tion chamber of the diesel engine. exhaust-gas behavior and noise. Therefore. bustion gases into the nozzle. The nozzle opening. ning. while direct-injection engines have diesel engine hole-type nozzles. the combustion chamber. Robert Bosch GmbH 120 Nozzles Nozzles The nozzle injects the fuel into the combus. ing pressure is at least 40 bar above the maxi- tion as effectively as possible. and the required injected fuel quantity relative sealing off the fuel-injection system from to crankshaft rotation. Because of the superior performance stresses from the engine and the fuel-injection combined with lower fuel consumption that it system. æ NMK1856E Indirect-injection (IDI) engines use pintle Combustion chamber of nozzles. (2 µm). zle will open and close the nozzle more than The injection durations on a car engine vary a billion times in the course of its service life. Such high-precision technology demands The pressure in the fuel-injection chamber an enormous amount of expertise in develop- can be as high as 2. 350 mm3 is closing (on cars this can take place as fre.000 times a minute if there (30 mm3 per raindrop). about the same as 12 large raindrops quently as 10.050 bar. (ms).. the sound wave from a loudspeaker only travels about The valve needle of a commercial-vehicle noz. and in the space of only 2 ms. the pressure and temperature of the com. That amount of are pre.and post-injection phases) fuel is forced at a velocity of 2.. A human hair is 30 times as thick (0.000 km/h the high flow-related stresses during fuel through an opening of less than 0. In one millisecond.050 bar as well as having to withstand between 3 mm3 (pre-injection) and 350 many other stresses such as mm3 (full-load delivery).33 m/ms Injected fuel quantity æ NMK1708-2E 1. 1 mm3 is equivalent the shocks caused by rapid opening and to half the size of a pinhead. on a commercial vehicle as 2.050 bar Clearance 0. materials. 33 cm.06 mm). between 1 mm3 (pre-injection) and 50 mm3 It provides a reliable seal at pressures as high (full-load delivery).06mm) Pressure 2.002mm Pinhead (2 mm3) Speed of sound 0.. Human hair (dia. The facts and figures below illustrate what modern nozzles are capable of. Robert Bosch GmbH Nozzles Dimensions of diesel fuel injection technology 121 Dimensions of diesel fuel-injection technology The world of diesel fuel injection is a world of The injection duration is 1..25 mm2 injection.002 mm bustion chamber. ment. 0. of a large executive car acting on an area the size of a fingernail...2 milliseconds superlatives. The valve-needle clearance is 0. That is equiva. production and measurement lent to the pressure produced by the weight techniques. 2 ms . 350 mm3 Injection duration 1. Robert Bosch GmbH 122 Nozzles Future development Future development 1 Main points of focus of nozzle development of the nozzle In view of the rapid development of new, high- Tribology performance engines and fuel-injection systems with sophisticated functionality (e.g. mul- Pressure-wave tiple injection phases), continual development resistance of the nozzle is a necessity. In addition, there Dead volume are a number of aspects of nozzle design which Injection- offer scope for innovation and further im- pattern shaping provement of diesel-engine performance in the future. The most important aims are: minimising untreated emissions in order Flow tolerance to reduce or even eliminate the expense of costly emission-control equipment that also presents difficulties with regard to waste disposal (e.g. soot filters) minimizing fuel consumption optimizing engine noise. There are various areas on which attention can be focussed in the future development of the injector (Figure 1) and a corresponding variety of development tools (Figure 2). New materials are also constantly being developed which Long-term stability offer improvements in durability. The use of Seat geometry multiple injection phases also has conse- Body heat quences for the nozzle design. resistance Orifice If different types of fuel (e.g. designer fu- Detrimental volume - diameter els) are used, this also affects injector design Blind hole - leading-edge contour æ NMK1861E because of the differences in viscosity or flow - shape - surface characteristics. Such changes in some cases - variability also demand new production processes such as laser machining for the injector jets. 2 Development tools for nozzles 3D flow simulation (a) Transparent nozzle Mechanical jet examination Optical jet examination (b) Transparent engine Test engine a b æ NMK1862E Robert Bosch GmbH Nozzles High-precision technology 123 High-precision technology The image associated with diesel engines the leading edges of the injection orifices are in many people’s minds is more one of heavy- rounded off by special abrasive fluids (hydro- duty machinery than high-precision engineer- erosion machining). ing. But modern diesel fuel-injection systems are made up of components that are manufac- These minute tolerances demand the use of tured to the highest degrees of accuracy and highly specialized and ultra-accurate measur- required to withstand enormous stresses. ing equipment such as optical 3-D coordinate measuring machines The nozzle is the interface between the fuel- for measuring the injection orifices, or injection system and the engine. It has to open laser interferometers for checking the and close precisely and reliably for the entire smoothness of the nozzle sealing faces. life of the engine. When it is closed, it must not leak. Because that would increase fuel The manufacture of diesel fuel-injection compo- consumption, adversely affect exhaust-gas nents is thus “high-volume, high-technology”. emissions and might even cause engine damage. In order that the nozzles seal reliably at the A matter of high-precision high pressures generated in modern fuel-injection systems such as the VR (VP44), CR, UPS and UIS designs (up to 2,050 bar), they 1 have to be specially designed and very precisely manufactured. By way of illustration, here are some examples: In order that the sealing face of the nozzle 2 body (1) provides a reliable seal, it has a dimensional tolerance of 0.001 mm (1 µm). That means it must be accurate to within approximately 4,000 metal atom layers! The valve-needle clearance (2) is 0.002...0.004 mm (2...4 µm). Finish- machining must be applied to obtain the dimensional tolerances of less than 0.001 mm (1 µm). The injection orifices (3) in the nozzles are created by an electro-erosion machining process. This process erodes the metal by vaporization caused by the high temperature generated by the spark discharge between an electrode and the workpiece. Using high-precision electrodes and accurately configured parameters, extremely precise holes with diameters of 0.12 æ NMK1709-2Y mm can be produced. Which means that the smallest injection orifice diameter is only twice 1 Nozzle-body sealing the thickness of a human hair (0.06 mm). In or- 3 face der to obtain better injection characteristics, 2 Valve-needle clearance 3 Injection orifice Robert Bosch GmbH 124 Nozzle holders Nozzle holders A nozzle holder combines with the matching Depending on design, the nozzle holder may nozzle to form the nozzle-and-holder assem- also contain seals and spacers. Standardized bly. There is a nozzle-and-holder assembly dimensions and combinations provide the fitted in the cylinder head for each engine required degree of adaptability combined cylinder (Figure 1). These components form with the minimum of component diversity. an important part of the fuel-injection system and help to shape engine performance, exhaust emissions and noise characteristics. In order that they are able to perform their func- 1 Schematic diagram of a nozzle-and-holder assembly on a direct-injection engine tion properly, they must be designed to suit the engine in which they are used. 1 The nozzle (4) in the nozzle holder sprays fuel into the diesel-engine combustion 11 2 chamber (6). The nozzle holder contains the Fig. 1 following essential components: 10 3 11 Fuel supply valve spring(s) (9) 9 12 Holder body 13 Fuel return which act(s) against the nozzle needle 8 14 Nozzle so as to close the nozzle; 15 Sealing gasket nozzle-retaining nut (8) 4 16 Combustion which retains and centers the nozzle; 7 5 chamber of filter (11) diesel engine for keeping dirt out of the nozzle; 6 æ UMK1719-1Y 17 Cylinder head 18 Nozzle-retaining nut connections for the fuel supply and return 19 Valve spring lines which are linked via the pressure 10 Pressure channel channel (10). 11 Filter 2 Bosch type designation codes for nozzle holders K B A L Z 105 S V XX… Ser. no. Specimen: last 7 digits of the K Nozzle holder drawing number B Attached by flange or clamp C External thread on nozzle-retaining nut V Test holder D Sleeve nut No letter = Standard nozzle holder A Spring at bottom Nozzle-holder dia. 17 mm (Type P nozzle), dia. 25 mm (Type S nozzle) P Nozzle (collar dia. 14.3 mm) E Spring at bottom S Nozzle (collar dia. 17 mm) Nozzle-holder dia. 21 mm (Type P and S nozzle) N Spring at bottom Nozzle-holder dia. 17/21 mm (Type P nozzle) Length (mm) L Long nozzle collar No letter = Short nozzle collar Fig. 2 æ SMK1831E Z Two inlet passages This number is stamped No letter = One inlet passage on the nozzle holder and enables precise identification. In addition. start of injection to the engine control unit. is in the center or at the side. depending on The fuel in the spring chamber has a damp- the required injection pattern. The needle-motion sensor signals the precise jection (DI) and indirect-injection (IDI) en. a Stepped nozzle For large-scale engines with a per-cylinder holder for commer- Depending on the fuel-injection system in output of more than 75 kW. the nozzle-and-holder assemblies or external threads. The descriptions.e. there are appli. Fig. clamps. In the common-rail and unit-injector high- pressure fuel-injection systems. can be applied to The fuel that leaks past the nozzle needle IDI nozzles as well. cial vehicles b Standard nozzle which they are used. engine types c Two-spring nozzle 3 Examples of nozzle-and-holder assemblies holder for cars d Standard nozzle holder for various engine types e Stepped nozzle holder without fuel- leakage connection for commercial vehicles f Stepped nozzle holder for commercial vehicles g Stepped nozzle holder for various engine types h Two-spring nozzle holder for cars i Stepped nozzle holder for various 2 cm a b c d e f g h i j engine types æ SMK1830Y j Standard nozzle holder with pintle nozzle for various types of IDI engine . But since modern Nozzle holders may be attached to the diesel engines are almost exclusively direct. Robert Bosch GmbH Nozzle holders 125 The design of the nozzle holder for direct-in. however. range of nozzles. there is a ing effect on the needle stroke at high injec- choice of tion volumes and engine speeds so that a standard nozzle holder (single-spring similar injection pattern to that of a two- nozzle holder) or spring nozzle holder is generated. without a fuel-return line. gines is basically the same. which may also be cooled. In many nozzle-holder the latter use pintle nozzles rather than the designs. so that a nozzle- holder which is particularly suited to situa. but bearing in mind that acts as lubrication. sleeve nuts injection. two-spring nozzle holder (not for unit pump systems). 3 tions where space is limited. Some nozzle holders function without Nozzle holders can be combined with a fuel leakage – i. a fuel-return line. and-holder assembly is unnecessary. The fuel-line connection illustrated here are mainly for DI engines. it is returned to the fuel tank by hole-type nozzles found in DI engines. nozzle holders may or cation-specific fuel-injector assemblies holder for various may not be fitted with needle-motion sensors. cylinder block by flanges. the nozzle A variation of those designs is the stepped is integral with the injector. (NOX) together with the HC and CO com. materials are preferred. which are caused by hetero. filters made of porous ceramic particulates. NO2. though the NOX conversion is quired oxidation catalytic converters. opment. The temperatures of over 600 °C required come established is as yet an unanswered to burn off the soot are not achieved by the question. There are of soot retained. spite the advances in internal engine design. Neverthe- has already been drastically reduced in less. Particulate filter Exhaust-gas treatment systems In order to be able to comply with ever Particulate filter stricter exhaust-gas emission limits. at a temperature substantially lower components of the particulate emissions. diesel engine under normal operation. Special catalytic-converter designs can being tested on selected fleets of busses with also simultaneously reduce nitrogen oxides a view to use in commercial vehicles. water (H2O) and carbon dioxide (CO2). the filter has to be regenerated. volume. and nitrogen oxides (NOX). It reduces hydro. Above a specific retention a number of different systems under devel. Item 9) so that filter and oxidizes the NO in the exhaust to it reaches its optimum operating tempera. The CRT system is currently cles. Temperature sensors. use on volume-production cars. of harmful emission: At present. emission control will become increasingly im. En- gine modifications such as retarded injec- Exhaust-gas treatment systems for diesel tion and intake air-flow constriction can engines aim primarily to reduce two types increase the temperature of the exhaust gas. Diesel oxidation-type catalytic converter CRT system With the CRT (Continuous Regeneration The diesel oxidation-type catalytic converter Trap) system.10 %. The pressure drop across the particulate This is particularly true for larger cars and filter is a possible indicator of the amount all types of commercial vehicle. sulfur fuel is stipulated. The soot that collects in the filter is ture as quickly as possible. Robert Bosch GmbH 126 Exhaust-gas treatment systems Diesel oxidation-type catalytic converter.. low- limited to 5. the exhaust-gas back pressure gradually recent years by developments such as high. fuel in the tank can reduce the temperature required to burn off the particulates in the The untreated emission of such substances particulate filter by about 100 °C. an oxidation catalytic con- (DOC) is fitted in the exhaust-gas system verter is fitted upstream of the particulate close to the engine (Figure 1. Which of them will eventually be. then continuously burned with NO2 as soon carbon (HC) and carbon monoxide (CO) as the temperature exceeds 250 °C – in other emissions. They are already in geneous mixture distribution in the com. A particulate filter (Figure 1.. a differential-pressure sensor and a soot sensor downstream of Oxidation-type catalytic converters are the particulate filter monitor the operation already in use on volume-production vehi. This increases fuel consumption and limits the life of the filter. out the particulates from the exhaust gas. together with some of the volatile words. bustion chamber. which result from Additive system the high temperatures at which diesel The use of an additive that is mixed with the combustion takes place. Item 10) filters portant for diesel engines in the future de. than required by conventional particulate fil- It converts these exhaust-gas products into ters where combustion with O2 takes place. . Because of the sensitivity to sulfur of the re- ponents. increases over time as the non-combustible pressure fuel-injection systems. deposits (the additive ash) remain in the filter. of the system. Because of that. by an oxidation-type catalytic converter (3) a three-way catalytic converter as used for which is either upstream of or integrated in gasoline engines with manifold fuel injec. This type of filter is called a Cat. converter is charged to such a degree that verter is being developed as a means of re. the storage phase needs to be terminated. This process is assisted excess (lean mixture. ducing the nitrogen-oxide emissions on car A model-based procedure calculates the diesel engines. This process involves the oxidation-type catalytic converter and the following two stages: particulate filter can be incorporated in a NOX storage in high-oxygen exhaust single unit.. 1 Exhaust system with oxidation-type catalytic converter and particulate filter with additive system 1 2 Fig. the ability to continue to ducing the NOX to nitrogen (N2). alyzed Soot Filter (CSF). CO and HC react with the excess oxygen in the exhaust gas to form CO2 As the amount of stored nitrogen oxide (the and H2O. an air excess. and are thus not available for re. Robert Bosch GmbH Exhaust-gas treatment systems Particulate filter. λ > 1). 2. Particulate Filter) system. When there is component to NO2. nitrogen oxides combine with metal catalytic converter oxides on the surface of the NOX accumulator-type catalytic converter to form nitrates A diesel engine always operates with an air (Figure 2 overleaf).10 seconds). There are two ways of detecting when the catalytic The NOX accumulator-type catalytic con. NOX accumulator-type catalytic converter 127 By using a catalytic coating on the filter. NOX storage When the oxygen content of the exhaust is NOX accumulator-type high.. the NOX accumulator-type catalytic con- tion cannot be used to reduce the nitrogen verter and which oxidizes the NO exhaust oxides (NOX) in the exhaust. (λ > 1. It is also sometimes NOX release and conversion in low-oxy- referred to as a CDPF (Catalyzed Diesel gen exhaust (λ < 1. from 30 seconds to several minutes). the convert them. 1 11 Additive control unit 12 Engine control unit 13 Additive pump 12 14 Fluid-level sensor 15 Additive tank 11 11 13 16 Additive metering 3 4 unit 17 Fuel tank 5 8 9 10 18 Diesel engine 19 Oxidation-type 2CO + O2 → 2CO2 catalytic converter 6 2NO + O2 → 2NO2 (DOC) 4 2C2H6 + 7O2 → 4CO2 + 6H2O 10 Particulate filter æ NMA0043Y 11 Temperature sensor 7 12 Differential-pressure sensor 13 Soot sensor . charge) increases. It breaks down the nitrogen quantity of stored nitrogen oxides on the oxides in a different way – this is because it basis of the temperature of the catalytic is able to store nitrogen oxides and then converter. bind nitrogen oxides decreases. because of the frequency of desul- amount of nitrogen oxides remaining in phation. “low oxygen” that the regeneration phase sures the nitrogen-oxide concentration in is complete (CO breakthrough). the NOX from cold. the engine “contaminates” the catalytic converter. pacity for NOX. i. measures the oxygen concentration in the exhaust gas and indicates by means of the . The NOX accumulator-type catalytic An oxygen sensor (Figure 2. a high sulfur content in the fuel has the NOX accumulator-type catalytic con. fuel with as volving the production of carbon dioxide low a sulfur content as possible (< 10 ppm) (CO2) and nitrogen (N2) (Figure 2). is required. Release/regeneration ( λ <1): type catalytic Ba(NO3)2 + CO → BaCO3 + 2NO + O2 æ NMA0044Y converter 2NO + 2CO → N2 + 2CO2 7 NOX sensor or oxygen sensor 8 Engine control unit An NOX sensor downstream of the NOX change of its signal from “high oxygen” to accumulator-type catalytic converter mea. The model-based procedure calculates the However. This is briefly run with a rich mixture (λ ≈ 0.e. By heating the exhaust gas to around There are two different methods of detecting 650 °C at λ ≈ 1. the stored nitrogen oxides have to be released and converted into Sulfur from the fuel and from lubricants N2. reversed to a large degree (desulfurization). be regenerated. is because the sulfur uses up the storage ca- Regeneration takes place in two stages in. In order for this to take place. an adverse effect on fuel consumption. For that reason. an electric exhaust-gas heater (2) accumulator-type catalytic converter has to can be used.95). sulfur contamination can be when the regeneration phase is complete. the exhaust. In order that good NOX reduction rates are NOX release and conversion also achieved when the engine is started Once a certain charge is reached. 2 1 Diesel engine 2 Exhaust heater (optional) 4 5 7 3 Oxidation-type catalytic converter 1 (optional) 2 3 6 4 Temperature sensor Storage ( λ >1): 5 Broadband oxygen 2NO + O2 → 2NO2 BaO3 + 2NO2 + 1/2O2 Ba(NO3)2 + CO2 sensor Type LSU 6 NOX accumulator. Item 7) converter is sometimes also called an NOX downstream of the catalytic converter Storage Catalyst (NSC). Robert Bosch GmbH 128 Exhaust-gas treatment systems NOX accumulator-type catalytic converter 2 Schematic diagram of exhaust-gas system with NOX accumulator-type catalytic converter 8 Fig. verter. Such systems will also be known as hydrolyzing catalytic converter then extracts four-way systems because they will limit not ammonia from the urea solution (Figure 3). stream of the reducing-agent injection point increases the efficiency of the system. consump. catalytic converter to form nitrogen and Combination systems demand very pow- water. Robert Bosch GmbH Exhaust-gas treatment systems SCR principle. A content. is added to the exhaust tion and highly efficient reduction of NOX gas in very precisely metered quantities. 3 11 Diesel engine 12 Temperature sensor 12 10 13 Oxidation-type 13 11 catalytic converter NO + NO2 + 2NH3 14 Injector for reducing → 2N2 + 3H2O agent 15 NOX sensor 16 Hydrolyzing catalytic converter 2 4 5 2 5 9 17 SCR catalytic converter 1 18 NH3 blocking 3 6 7 8 catalytic converter 19 NH3 sensor Thermolysis: (NH3)2CO → 2NH3 + HNCO 10 Engine control unit æ NMA0046Y Hydrolysis: HNCO + H2O → NH3 + CO2 11 Reducing-agent 2NO + O2 → NO2 pump 12 Reducing-agent tank 13 Fluid-level sensor . such systems can save as much as overall system is monitored by gas sensors 10% on fuel consumption. Systems combin- also perform the function of the hydrolyzing ing NOX accumulator-type catalytic convert- converter so that a separate unit is not ers with particulate filters. the detected NOX concentration upstream of tion-optimized engine calibration is possible. downstream SCR system reduces the NOX emissions. Combination systems 129 SCR principle Combination systems In exhaust-gas denitrification processes In order to be able to comply with future based on the SCR (Selective Catalytic Re. being ready for volume production. rently in the course of development. only NOX and particulate output but also The ammonia reacts with NOX in the SCR HC and CO emissions. such as vehicles will require exhaust-gas treatment a dilute urea solution with a concentration systems that enable both particulate filtra- of 32. or SCR catalytic required. a reducing agent. A reducing agent is injected in Because of the high NOX reduction rates quantities based on a stored data map and (up to 90 % in the European transient test exhaust-gas temperature or on the basis of cycle for commercial vehicles). the catalytic converter. Soot is continuously oxidized by a catalyzed ing catalytic converter) downstream of the diesel particulate filter (CDPF) while the SCR converter prevents NH3 emission. An ox. 3 SCR system Fig. many diesel duction) principle.5% by weight. converters with particulate filters are cur- An oxidation-type catalytic converter up. SCR systems for (for NOX and/or NH3) and temperature commercial-vehicle applications are close to testing points. The function of the As a result. Modern SCR catalytic converters can erful engine control units. exhaust-gas emission limits. Example system idation-type catalytic converter (NH3 block. Centrifugal turbocharger. 27 –. 117 Master-and-slave configuration Compression. 116 Combustion pressure limit. 4ff Discrete cylinder systems. 82ff Idling. Because of the commercial-vehicle engines. Additive system. 70 Fuels. 126ff M method. 64 Characteristic data of injection E –. 56ff most important alternati. 118f indicates a synonym Actuators. 32f technology. 82f Injection pattern. 121 p Superchargers now spanning more than Altitude limits. 49 Multi-stage turbocharging. 82 Indirect-injection engine concepts will be known Basic principles (diesel engine). 19 O Operating conditions. 22 Electric booster (turbocharger). 116 M –. 12 Engine characteristic data. 119 (e. 33 H Over the history of the Air-intake module. 50ff –. 114 Glow-plug control unit. 41 Exhaust-gas temperature limit. 126 Diesel aircraft engines. 55 ves in such cases. 19 Comprex supercharger Excess-air factor λ. 86 Compressor p Supercharger Engine test bench. 117 N Control valve. 47 Intercooler. 69 technical terms and ab. 74ff Inlet flaps.g. Indirect injection. 46 Downsizing. 74 Injection pressure. 54 rison with other technical Calibration tools. Method of operation. 120 Combustion chambers. 55ff This index includes the –. 23 Direct injection. 7 breviations have been Application-related adaptation of p Unit injector system coined. Cetane number. Basic principles (fuel injection). System overview. 92 Electropneumatic transducers. 116 F NOx accumulator-type catalytic Control. 25 Efficiency. 110 Medium power. 20 Oxidation-type catalytic converter. System overview. 65f Injection quantity. System overview. 14ff Intake-manifold valve. 58 Glow-plug preheating. 63 Eco-fuels p Alternative fuels Intake-air heating. 28ff Cylinder-charge control. 114 Fan control function. Method of operation. 102ff p Discrete-fuel-injection pumps History of the diesel engine. 22 Continuous braking systems. Injection duration. p Compression) A Dead volume. 44 In-line injection pumps. 118 Nozzle holder. 111ff –. 8 (control units). 11 Nozzle-and-holder assembly. 124f turbocharging. 118f or related term. 126 . 116ff Detrimental volume. 70 Characteristic data (engine). Electronic Diesel Control. 106ff p Unit pump system I wide range of areas in Areas of use (diesel engine). 38 literature. 70ff systems (overview). 35ff Diesel-and-water emulsions. System overview. 123 a century – numerous Application-related adaptation Discrete cylinder systems History of diesel fuel injection. 28f Dynamic supercharging. 25f High-precision technology. 8 –. 10ff –. 47 Four-stroke cycle. 100ff Areas of application. 9 Air filter. 124f Control-sleeve in-line fuel-injection Fuel delivery point. of car engines. 60f facilitating easier compa. 83 Injection characteristics. Method of operation. 34ff Full power. 26f it is inevitable that some B Applications. 127f Controlled two-stage Flame glow plug. p Application-related adaptation –. 50f p Pressure-wave supercharger Exhaust-gas recirculation. Use with heavy oil. 53 Nozzles. 120ff pump. C Distributor injection pump. 50f Mixture homogeneity. thus Calibration Areas of application. Robert Bosch GmbH 130 Index of technical terms Index of technical terms An arrow pointing to Technical Terms D G a term printed in italics Data processing (control unit). 68 Emission control systems. Method of operation. 36 Dimensions of diesel fuel-injection Helical-vane supercharger diesel engine – a period Alternative fuels. Discrete injection pump. 92ff Engine brake. 39 Areas of application. 59 Glow plugs. 19 which the diesel is used. 47 Constant-pressure turbocharging. 117 converter. 47 Common-rail system. 17ff Overrunning. 66 p Indirect injection by more than one term. 21ff Operating statuses. 42f SCR principle. 47 Volumetric efficiency. 39ff p Distributor injection pumps Two-stage injection pattern Positive-displacement supercharger (Unit Pump System). 58 nozzles. 41 Areas of application. 14f Throttle valve p Control valve p-ª diagram. 52f Starting assistance systems. Robert Bosch GmbH Index of technical terms 131 P T p-V diagram. 83 Retarder. 84 p Common-rail system –. 67 R –. 84 –. 57 p Direct injection Pressure-accumulator Unit injector system. 32 Valve timing. 31 Superchargers. 13 Port-controlled fuel-injection systems Turbocharger pressure limits. 84ff Reciprocating piston supercharger Use with heavy oil p Superchargers (large-scale engines). 14f –. 118f Starting. 38ff Swirl actuator. 38 Smoke limit. 14 (turbocharger). 15 Timing characteristics (injection). 84ff Pressure-wave supercharger. 20 Sulfur content (fuel). 41f p Common-rail system Z p Unit injector system Zero load. 22 Split combustion chamber p Indirect injection Start of injection. 124 Power output. Post-injection. fuel-injection system Areas of application. 45f Supercharging and turbocharging. 123 Particulate filter. 117 Rootes supercharger V p Superchargers Valve overlap. 23 p In-line-fuel-injection pumps Turbocharger. 21 Solenoid-valve controlled W injection systems Wastegate turbocharger. 35 Tolerances. 13 Precombustion chamber system U p Indirect injection Undivided combustion chamber Pre-injection. 43 Sequential turbocharging. System overview. (fuel injectors). 17ff Static operating conditions. Method of operation. 126f Torque. Method of operation. 56 p Superchargers Type designation codes. 48 Unit pump system Pulse turbocharging. 129 Variable-inlet-valve turbine Seiliger process. System overview. 12 Running on alcohol. 19 p Unit pump system p Distributor injection pumps Speed limits. 12 Variable turbine geometry S (turbocharger). 38 Swirl-chamber system p Indirect injection . 67 Pressure-volume diagram. 59 Particle sizes (intake air). IV.3596 hp) p Calibration tools p ADM V CDPF: Catalyzed Diesel Particulate M Vh: Swept volume of an engine Filter (p Particulate filter) MDA: Measured Data Analyzer cylinder CFPP: Cold Filter Plugging Point p Calibration tools VH: Overall cylinder capacity CN: p Cetane number MI: Main Injection (phase) of an engine CO: Carbon monoxide VTG turbocharger: Turbocharger with CO2: Carbon dioxide N p variable turbine geometry CR system: p Common-rail system NEDC: New European Driving Cycle CRS: p Common Rail System (exhaust testing cycle) W CRT: Continuous Regeneration Trap NH3: Ammonia WSD: Wear Scar Diameter (p Particulate filter system) NOx:Collective abbreviation for (HFRR method) CSF: Catalyzed Soot Filter nitrogen oxides (p Particulate filter) NO (nitrogen monoxide) and NO2 (nitrogen dioxide) D DI: Direct Injection P DOC: Diesel Oxidation Catalyst PF: p Particulate filter PI: Pre-injection E PO: Post Injection EDC: Electronic Diesel Control ppm: Parts per million EMC: Electromagnetic compatibility (1. II.1%) EN: European standard PROF: Programming of Flash- ESP: Electronic stability program EPROM p Calibration tools EU: European Union EURO I.000 ppm = 0. V: Exhaust emission standards in the p EU . III.7355 kW) I TCS: Traction Control System IDI: Indirect Injection TDC: Top Dead Center C INCA: Integrated Calibration (piston/crankshaft) CAN: Controller Area Network and Acquisition System CCRS: Current Control Rate Shaping (p Calibration tools) U (p Two-stage injection pattern) UIS: p Unit Injector System CDM: Calibration Data Manager K UPS: p Unit Pump System (Application Data Manager) kW: Kilowatt (1 kW = 1. Robert Bosch GmbH 132 Index of technical terms Abbreviations Abbreviations F R FAME: Fatty Acid Methyl Ester RME: Rape-oil methyl ester A (p Alternative fuels) p Alternative fuels ABS: Antilock braking system Flash EPROM: Flash Erasable ACC: Adaptive Cruise Control Programmable Read Only Memory S ADM: Application Data Manager SCR: Selective Catalytic Reduction p Calibration tools p CDM H (p SCR ) AGR: p Exhaust-Gas Recirculation H2S: Hydrogen sulphide SO2: Sulfur dioxide HC: Hydrocarbon SULEV: Super Ultra-Low Emission B HFM: Hot film air mass-flow meter Vehicle (USA exhaust-gas emission BDC: Bottom Dead Center HFRR method: High Frequency legislation for cars) (piston/crankshaft) Reciprocating Rig method bhp: brake horse power T (1 bhp = 0.

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