RESEARCH OF A USING DIESEL ENGINE WITH AUTOMATIC VARIABLE COMPRESSION RATIO

Abstract

In conventional engines, the compression ratio is constant, and their performances are therefore a compromise between conflicting requirements. One fundamental problem is that drive units in the vehicles must successfully run at variable regimes in a different ambient condition. If a diesel engine has a fixed compression ratio, a minimum value must be chosen that can achieve a reliable self-ignition when starting engines in cold start conditions. At diesel engines, variable compression ratio (VCR) provides control and directions over peak cylinder pressure and increase specific power output if supercharging is in use. Furthermore, VCR improves cold start ability, light load operation, multi-fuel capability, fuel economy and reduces toxic exhaust emission. Specifically, it’s possible to reduce emissions of nitric oxides at high levels, when the compression ratio value is automatically reduced. When automatic compression ratio change, normal levels of moving bearing pairs in the engine is reduced and thereby mechanical levels, that result in lower fuel consumptions. This paper contains results both, theoretical and laboratory research, of the impact automatic variable compression ratio have on parameters combustion process in diesel engines. Alternative methods of implementing VCR are illustrated and critically examined.