Fuel Injection System Components

10/5/13Fuel Injection System Components DieselNet Technology Guide » Diesel Fuel Injection www.DieselNet.com. Copyright © Ecopoint Inc. Revision 2013.06 Fuel Injection System Components Hannu Jääskeläinen, Magdi K. Khair This is a preview of the paper, limited to some initial content. Full access requires DieselNet subscription. Please log in to view the complete version of this paper. Abstract: The fuel injection system can be divided into low-pressure and high-pressure sides. The low-pressure components include the fuel tank, fuel supply pump and fuel filter. The high-pressure side components include a high pressure pump, accumulator, fuel injector and fuel injector nozzle. A number of injection nozzle designs and different actuation methods have been developed for use with different types of fuel injection systems. Low-Pressure Side Components Overview Fuel Tank and Fuel Supply Pump Fuel Filter Fuel Heaters & Coolers High-Pressure Side Components Overview High Pressure Pump Accumulator Fuel Injector and Fuel Injection Nozzle Fuel Metering Nozzle Needle Control Actuators 1. Low-Pressure Side Components 1.1 Overview In order for the fuel injection system to fulfill its purpose, fuel must be transferred to it from the fuel tank. This is the role of the low-pressure fuel system components. The low pressure side of the fuel system consists of a number of components including the fuel tank, one or more fuel supply pumps and one or more fuel filters. In addition, many fuel systems contain coolers and/or heaters to better control fuel temperature. Figure 1 illustrates two examples of schematics for low pressure fuel systems, one for a www.dieselnet.com/tech/diesel_fi_comp.php#hpintro 1/5 Examples of Low Pressure Fuel Systems for Heavy-Duty and Light-Duty Diesel Vehicles 1. the excess fuel that is heated by its contact with hot engine components can be returned to the tank or fuel filter to improve the vehicle’s low temperature operability.10/5/13 Fuel Injection System Components heavy-duty diesel truck and one for a light-duty diesel passenger car [CRC 2007][CRC 2008]. incorporate a mechanically driven supply pump and the high pressure pump in one unit. The fuel tank should be corrosion-resistant and leakproof to pressures of at least 30 kPa. often referred to as the lift pump. Fuel pumps are commonly sized to deliver more fuel than is consumed by the engine at any particular operating system. The fuel supply pump. is responsible for drawing fuel from the tank and delivering it to the high pressure pump.3 Fuel Filter www. so called tandem pumps are units that incorporate a fuel pump and a vacuum pump for the brake booster.com/tech/diesel_fi_comp. It must also use some means to prevent excessive pressure accumulation such as a vent or a safety valve. For example. Some fuel pumps may be incorporated into units that serve other functions.php#hpintro 2/5 . Fuel return Injector pump supply Fuel return Injector pump supply Secondary fuel filter Fuel pump Fuel filter Thermostatic control Primary fuel filter Fuel tank Fuel pump Fuel tank MY 2003 Caterpillar C12 fuel system in an International truck MY 2005 Volkswagen Passat with 2. The fuel tank also serves as an important means of dissipating heat from the fuel that is returned from the engine [Bosch 1971].0 L TDI engine fuel system Figure 1. 1. pumps and other engine components and maintaining a more constant temperature of the fuel in the entire fuel system. Some fuel systems. Also.2 Fuel Tank and Fuel Supply Pump The fuel tank is a reservoir that holds the fuel supply and helps maintain its temperature at a level below its flash point.dieselnet. such as those based on a distributor type pump. Using an electrically driven fuel pump allows the pump to be placed anywhere in the fuel system including inside the fuel tank. Pumps driven by the engine are attached to the engine. This extra fuel flow can serve a number of important functions including providing extra fuel to help to cool injectors. Modern day fuel pumps can be electrically or mechanically driven by the engine. In many cases. a mixture of packed cotton thread and wood fibres and wound cotton have also been used [Brady 1996]. clearances and stresses on high pressure components increase and the need for clean fuel becomes event more critical. The degree of filtration required depends on the specific application. Micro glass fibres can also be used but because of the risk of migration of small glass fibre pieces broken off from the main element into critical fuel system components. In addition to keeping solid particles out of the fuel supply and injection equipment. wood chips.dieselnet. pleated paper. As shown in Figure 1.php#hpintro 3/5 . In the past. As fuel systems evolve. Two Types of Fuel Filters (a) Box type. In general. as shown in Figure 2. when two filters are used in series. Filters can be constructed of metal or plastic. while the secondary filter is capable of retaining particles greater than 2-10 µm. the primary filter retains particles down to about 10 . Filters with a replaceable element have to be thoroughly cleaned when replacing elements and care must be taken to avoid any dirt residue that could migrate to the intricate parts of the fuel injection system. One-stage systems remove larger and smaller particles in a single filter.com/tech/diesel_fi_comp. Fuel filters help reduce damage and premature wear from contaminants by retaining very fine particles and water to prevent them from entering the fuel injection system. packed cotton thread. The secondary filter is required to withstand higher pressures and remove smaller particles that can damage the engine components. Two stage filter system typically uses a primary filter on the inlet side of the fuel transfer pump and a secondary filter on the outlet side. their use in some applications is avoided [Petiteaux 2009].10/5/13 Fuel Injection System Components Trouble-free operation of a diesel injection system is possible only with filtered fuel. a course screen is also located at the fuel intake located in the fuel tank. (b) Element type Common materials for modern fuel filter elements are synthetic fibres and/or cellulose. fuel systems can contain one or more stages of filtration. Figure 2. The box-type filter is that which can be completely replaced as needed and does not require cleaning.30 µm. Both the capability of fuel filters to keep up with demands for cleaner fuel [Salvador 2009] as well as methods quantifying acceptable fuel contamination levels have needed to evolve [van Stockhausen 2009]. Filters can be a box-type or replacement element design. water in fuel must www. The primary filter is required to remove larger particles. Figure 3. Hydrophobic barrier media. Water can also freeze in cold temperature conditions and ice may block small fuel injection system passages thus cutting off the fuel supply to the rest of the fuel injection system. massive droplets are formed. Increased use of surface active fuel additives and fuel components such as biodiesel have rendered conventional separating media less effective and filter manufacturers have needed to develop new approaches such as composite media and ultra-high surface area coalescing media [Stanfel 2009] [Pangestu 2009][Bessee 2009]. Free water can damage fuel lubricated components in the fuel injection system.php#hpintro 4/5 . The water moves through the filter with the fuel and on the downstream side. such as glass micro-fibre.com/tech/diesel_fi_comp. Water can be removed from the fuel using two common approaches. Hydrophilic depth coalescing media. falls out of the fuel flow into a collection cup. Much better removal efficiencies can be achieved with a filter media that separates water. rejects water and causes it to bead up on the upstream surface. www. The incoming fuel can be subject to centrifugal forces that separates the denser water from the fuel. Fuel Filter Equipped with Water Separator Different water separation media operate under different principles. The water in the fuel associates with the glass fibres and over time as more water enters from the upstream side. Figure 3 shows a filter using a combination of media-type and centrifugal approaches.dieselnet.10/5/13 Fuel Injection System Components also be prevented from entering critical fuel injection system components. they run down the face of the element into a cup under the force of gravity. As the beads become larger. such as silicone treated cellulose. Methods of quantifying fuel/water separation performance have also been affected [Stone 2009]. has a high affinity for water. .com/tech/diesel_fi_comp.D. Vancouver Community College and HiTech Consulting Limited. SAE Technical Paper 2009-01-0871. et al. C.4271/2009-01-0874 Stanfel. 2007. The presence of gaseous substances in the fuel can cause difficulties in starting as well as normal engine operation in high temperature environments.Fuel Injection Pumps PE and PF”.M . “Filtration technology challenges for common-rail diesel engine fuel systems”. “The effects of diesel fuel additives and water separation performance”. 1996.dieselnet.crcao. Fuel overflow and leak-off fuel returning to the tank also carries air and fuel vapor. 2009. SAE Technical Paper 2009-010874. F. 2009.. 22-25 Stone.4271/2009-01-0875 van Stockhausen. Robert Bosch GmbH. Therefore.M . SAE Technical Paper 2009-01-0868. “M odern Diesel Technology”.. M . “Fuel filtration: protecting the diesel engine”. M ay/June 2009. filter change indicators.. Hutzler. engine coolant or recirculated fuel. Atlanta.N.crcao. 650. CRC Report No. Inc. C. 2009. thermal diverter valves.pdf Pangestu. Filtration + Separation. http://www.4271/2009-01-0868 Bosch. Englewood Cliffs. doi:10. 2009.. GA. 649. de-aerators.php#hpintro 5/5 . doi:10. SAE Technical Paper 2009-01-0870. bleeder valves and de-aerators are used to rid the fuel supply of vapors and air to ensure trouble-free engine operation.where we are and where we are going”. “M edia for water separation from biodiesel-ultra low sulfur diesel blends”. SAE Technical Paper 2009-01-0875. 1971 Brady. doi:10. http://www. “Procedure for determining the allowable particle contamination for diesel fuel injection equipment (FIE)”.. Stanfel. et al. “Diesel fuel/water separation test methods . A.B. C. GA. “Biodiesel Blend Low-Temperature Performance Validation”. S. Coordinating Research Council. Common heating methods use electric heaters. CRC Report No.. Coordinating Research Council.4271/2009-01-0871 Petiteaux. “Innovative Water Separation Technology and Electrostatic Discharge System Developed and Validated for the New Diesel Fuel Filtration M odule of the Future Ford Diesel F-Series”. G. Inc. Atlanta. 2008. SAE Technical Paper 2009-01-1459.com/reports/recentstudies2007/CRC%20649%20Complete%20Report..10/5/13 Fuel Injection System Components Fuel filters can also contain additional features such as fuel heaters.4271/2009-01-1459 Salvador. Two approaches that use warm return fuel to heat the incoming fuel are shown in Figure 1. “Evaluation Of Low Temperature Operability Performance Of Light-Duty Diesel Vehicles For North America”. 2009.. “Fuel Injection Equipment for Diesel Engines . R. Prentice Hall. water-in-fuel sensors. A fuel preheater helps minimize the accumulation of wax crystals that can form in the fuel as it cools to low temperatures. 1st ed. doi:10.. References Bessee. 2009. doi:10..pdf CRC..4271/2009-01-0870 ### www.. 1971. doi:10.org/reports/recentstudies2008/DP-2a-07/CRC%20650.. 2009. W. New Jersey CRC..