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 characteristics of the automobile engine is its wide operating range in terms of 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 to 15% at low partial loads. It is the latter case which is mainly encountered, 80 to 90% of the time, in urban vehicle use.
To overcome this deficit, constructive solutions must be sought which make it possible to obtain a significant increase in efficiency within this operating interval. One of them consists of a variation of the compression volumetric ratio by the variation of the volume of the combustion chamber.