Control system compression ratio for a combustion engine

The invention relates to a system (1) compression ratio control for an internal combustion engine, this system comprising: - a cylinder (3), - a movable piston (4) forming with the cylinder a combustion chamber (5 ), - a connecting rod (6) arranged to move the piston, a grip member (10) interposed between the connecting rod and a crankshaft so that the rod is slidable relative to this body grip, this grip member comprising an electrorheological fluid or magnetorheologigue arranged to regulate the stroke of the rod relative to the grip body.