BYG.Sulochana Babu B.Nagendra Prasad 21/03/15 VCR Engines 1 Outline of Presentation 21/03/15 VCR Engines 2 . In a VCR engine high compression ratio is employed for greater efficiency and low load operation. Low compression ratio is employed at full load allowing the turbo charger to work without problem of detonation. 21/03/15 VCR Engines 3 .What is VCR engines? It is the technology to adjust internal combustion engine cylinder compression ratio. 21/03/15 VCR Engines 4 . Fuel consumption is 30 percent lower than conventional engine by achieving variation of compression ratio from 8:1 to 16:1 depending on the load.SAAB Automobile Introduced variable compression to the world at the Geneva motor show in 2000. VCR Engines reduces combustion chamber temperature and increases charge and thermal efficiency. Methods to obtainVCR 21/03/15 VCR Engines 5 . 21/03/15 VCR Engines 6 . The piston could be maintained at an intermediate position corresponding to the optimum compression ratio for a particular condition.Variation of combustion chamber volume The volume of combustion chamber is changed to obtain the variable compression ratio by moving a small secondary piston which communicates with the chamber. 21/03/15 VCR Engines 7 .2. 3.Variable Compression height piston Variation on compression height of the piston offers potentially the most attractive route to the production of VCR engine. 21/03/15 VCR Engines 8 . But it requires relatively minor changes to the base engine architecture when compared to other options. Movement of the crankshaft or crankpins 21/03/15 VCR Engines 9 .4. Multilink mechanisms A popular approach has been to replace the connecting rod with a two piece design in which an upper member connects with the piston while a lower member connects with the crankshaft. 21/03/15 VCR Engines 10 .5. 21/03/15 VCR Engines 11 . Experimental Setup 21/03/15 VCR Engines 12 . which in turn is fixed. which joins the link 2 to crank shaft. Now the power transmitting link to the crank shaft is link 3.The connecting rod is made of three links. 21/03/15 VCR Engines 13 . Link 1 connects the piston to the intermediate link 2. thus giving a constant injection without stopping the crank shaft. 21/03/15 VCR Engines 14 .Working of VCR engine When the piston is moving to the bottom dead center the link 1 pushes the link 2 directly. when the piston is moving towards the top dead center the link 3 will continue to be in motion but keeping the link 1 in a constant. As main link 1 will dwell at the top dead center. thus the crank shaft also moving thus producing no dwell at the bottom dead center. The dwell that is required at the top dead center will depend on the positioning and the length of the links. 21/03/15 VCR Engines 15 . This enable low vibration property of in-line 4 cylinder engine. the piston's reciprocal action achieves ideal simple harmonic motion. With the multilink VCR mechanism. 21/03/15 VCR Engines 16 .Conclusions The newly developed multi link mechanism enables optimum compression ratio control such as the fuel economy (thermal efficiency) of a engine. 21/03/15 VCR Engines 17 . 21/03/15 VCR Engines 18 .