Abstract: A four-stroke internal combustion engine including variable compression ratio comprises a crankcase including a crankshaft having a crankpin and being supported by the crankcase and rotatable with respect thereto about a crankshaft axis, a connecting rod including a big end and a small end, a crank member being rotatably mounted on the crankpin, and comprising at least a bearing portion which is eccentrically disposed with respect to the crankpin, a crank member drive system for rotating the crank member at a rotation frequency with respect to the crankcase which is half of that of the crankshaft, and a control system for operating the engine with repetitive cycles, wherein the compression ratio in the compression stroke is changed. The control system is configured to interrupt the repetitive cycles by rotating the crankshaft an additional single revolution between two successive combustion strokes for switching between a high and low compression ratio.

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 reciprocating piston mechanism comprises a crankcase and a crankshaft. The crankshaft is supported by the crankcase and rotatable with respect thereto about a crankshaft axis. The mechanism further comprises at least a connecting rod including a big end and a small end, a piston which is rotatably connected to the small end, and a crank member which is rotatably mounted on the crankpin. The crank member comprises at least a bearing portion and has an outer circumferential wall which bears the big end of the rod such that the rod is rotatably mounted on the bearing portion of the crank member via the big end. The crank member is provided with a crank member gear. The crank member gear meshes with at least an intermediate gear, which also meshes with an auxiliary gear. The auxiliary gear is fixed to an auxiliary shaft that extends concentrically through the crankshaft.

Abstract: A method of assembling a crankshaft and a crank member comprises supplying a crankshaft including a crankpin which extends between crank arms, supplying two halves of a crank member, which are fixed to each other about the crankpin such that in assembled condition the crank member is rotatable about the crankpin and comprises a bearing portion having an outer circumferential wall for bearing a big end of a connecting rod and an external crank member gear for driving the crank member about the crankpin, wherein the halves are fitted about the crankpin, hence creating two contact faces at opposite sides of the crankpin, after which both halves are fixed to each other in circumferential direction by means of applying at least a fixation at a fixing place located remote from the bearing portion and the toothed surface of the crank member gear.

Abstract: A reciprocating piston mechanism comprises a crankcase and a crankshaft. The crankshaft is supported by the crankcase and rotatable with respect thereto about a crankshaft axis. The mechanism further comprises at least a connecting rod including a big end and a small end, a piston which is rotatably connected to the small end, and a crank member which is rotatably mounted on the crankpin. The crank member comprises at least a bearing portion and has an outer circumferential wall which bears the big end of the rod such that the rod is rotatably mounted on the bearing portion of the crank member via the big end. The crank member is provided with a crank member gear. The crank member gear meshes with at least an intermediate gear, which also meshes with an auxiliary gear. The auxiliary gear is fixed to an auxiliary shaft that extends concentrically through the crankshaft.

Abstract: An engine comprises a crankcase and a crankshaft. The crankshaft has a central main portion, a crankpin and a crankshaft web. A crank member is rotatably and eccentrically mounted on the crankpin. An external crank member gear meshes with an external drive shaft gear. A driven portion of the drive shaft is located at a side of the crankshaft web which is opposite to its side where the crankpin is located and is drivably coupled via a first transmission to an intermediate member which is rotatably mounted to the crankshaft. The intermediate member is drivably coupled to a control shaft portion of a control shaft via a second transmission which control shaft portion is located at axial distance of the driven portion of the drive shaft and the control shaft is rotatable at a fixed rotational position with respect to the crankcase under operating conditions at fixed compression ratio.

Abstract: A four-stroke internal combustion engine with variable compression ratio, comprises a crankcase, a crankshaft, a connecting rod having a big end and a small end. A piston is rotatably connected to the small end. A crank member rotatably mounted on the crankpin has a bearing portion which is eccentrically disposed with respect to the crankpin, wherein the bearing portion has an outer circumferential wall including a location of maximum eccentricity (P) which bears the big end of the connecting rod such that the connecting rod is rotatably mounted on the bearing portion of the crank member via the big end. Under operating conditions at or close to top dead center of the piston the angle between the connecting rod plane and the piston plane changes from a pre-angle before top dead center to a post-angle after top dead center.

Abstract: A reciprocating piston mechanism comprises a crankcase and a crankshaft (rotatable about a crankshaft axis) which has at least a crankpin having a crankpin. A connecting rod includes a big end rotatably mounted on the crankpin and a small end rotatably connected to a piston. The crank member is provided with a crank member gear that meshes with an intermediate gear, both gears of which are external gears along with first and second auxiliary gears. The intermediate gear meshes with the first auxiliary gear. The first auxiliary gear is fixed to the second auxiliary gear via a common auxiliary shaft that mounts to the crankshaft and rotates with respect thereto about an auxiliary shaft axis that extends parallel to the crankshaft axis. The second auxiliary gear meshes with a central gear. The central gear is an internal gear, which has a center line that coincides with the crankshaft axis.

Abstract: A crank-connecting rod mechanism for an internal combustion engine or the like comprising a shaft rotating around its axis, a first crank fixed to the shaft and a crank pin fixed to the first crank. A crank pin extends parallel to but at a first radial distance from the shaft. A second crank rotatably mounted onto the first crank pin is fixed to a second crank pin having an axis at a second radial distance from the axis of the first crank pin. A connecting rod is rotatably mounted on the second crank pin. Rotary means are provided to force the second crank to rotate relative to the first crank upon a rotation of the shaft.