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 speeds and loads. The full load "foot to the floor" is rare, the use of the motor is mainly done in partial loads. The maximum efficiency of the spark ignition engine, which is about 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, we must seek constructive solutions that achieve operation in this interval a significant increase in yield. One of them consists in a variation of the compression ratio by varying the volume of the combustion chamber.