Introduction on engines with variable compression ratio and interest overview Adrian CLENCI and Pierre PODEVIN. University of Pitesti, Romania. Conservatoire National des Arts et Métiers in Paris, France
One of the essential features of the automobile engine is its wide operating range in terms of engine speeds and loads. The full load "foot to the floor" is rare, the use of the engine is mainly done in partial loads. The maximum efficiency of the spark ignition engine, which is approximately 30%, does not exceed 10 at 15% at low partial loads. It is this last case which is mainly met, 80 at 90% of the time, in urban use of the vehicle.
To overcome this deficit, it is necessary to look for the constructive solutions which make it possible to obtain in this interval of operation a significant increase of the yield. One of them consists of a variation of the volumetric ratio of compression by the variation of the volume of the combustion chamber.