Abstract: A heat engine includes a system for varying the compression ratio of the engine. The compression ratio varying system comprises: at least one eccentric part rotatably mounted on a crank pin. The eccentric part has an eccentric outer face that co-operates with one end of a rod, as well as at least one ring gear. A device for controlling the angular position of the eccentric part, includes an actuating pinion mounted on an actuating shaft. The control device also comprises at least one stepped intermediate pinion having at least first and second steps each formed by a pinion, the pinion of the first step meshing with the actuating pinion and the pinion of the second step meshing with the gear of the eccentric part.

Abstract: A heat engine includes a system for varying compression ratio, which comprises a crankshaft including at least a crank pin and an arm, and an eccentric part rotatably mounted on the crank pin. The eccentric part includes an eccentric outer surface intended for engaging with one end of a connecting rod and one toothed ring gear. A control device controls the angular position of the eccentric part. The control device includes an actuating shaft provided with an actuating pinion, at least one intermediate shaft passing axially, from side to side, through a journal and the arm of said crankshaft via a corresponding bore. The intermediate shaft is provided with a first intermediate pinion meshing with said actuating pinion and a second intermediate pinion meshing with an eccentric part.

Abstract: A heat engine includes a system for varying the compression ratio of the engine. The compression ratio varying system comprises: at least one eccentric part rotatably mounted on a crank pin. The eccentric part has an eccentric outer face that co-operates with one end of a rod, as well as at least one ring gear. A device for controlling the angular position of the eccentric part, includes an actuating pinion mounted on an actuating shaft. The control device also comprises at least one stepped intermediate pinion having at least first and second steps each formed by a pinion, the pinion of the first step meshing with the actuating pinion and the pinion of the second step meshing with the gear of the eccentric part.