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.

A cam rotary engine power system of internal combustion type, making use of the cam and a plurality of cam followers to form cam mechanisms, and forming a plurality of circumferential distributed sealing working chambers with the inner-cavity-member, the external-rotating-surface-member and the end-cover-member. The volume of those chambers change with the relative rotation of the cam and the cam followers, in which the intake, compression, power and exhaust processes of the Otto cycle are completed by valve coordination. The chemical energy produced by gas combustion is directly converted into the mechanical energy of the rotor in the form of fixed axis rotation. The power system does not set the crankshaft of piston engine, and the high pressure gas directly drives the rotor to rotate and output power. The structure of this power system is relatively simple and its parameters can be adjusted in a wide range.

A cam rotary engine power system of internal combustion type, making use of the cam and a plurality of cam followers to form cam mechanisms, and forming a plurality of circumferential distributed sealing working chambers with the inner-cavity-member, the external-rotating-surface-member and the end-cover-member. The volume of those chambers change with the relative rotation of the cam and the cam followers, in which the intake, compression, power and exhaust processes of the Otto cycle are completed by valve coordination. The chemical energy produced by gas combustion is directly converted into the mechanical energy of the rotor in the form of fixed axis rotation. The power system does not set the crankshaft of piston engine, and the high pressure gas directly drives the rotor to rotate and output power. The structure of this power system is relatively simple and its parameters can be adjusted in a wide range.

There is a problem of a difficulty in estimating the temporal change of the MBT for each of cylinders with light calculation load and high accuracy. An object of the present invention is to provide a control device capable of detecting a temporal change in the fuel efficiency optimum ignition timing (MBT) for each of cylinders. Therefore, the control device for internal combustion engine includes a control unit (CPU) that estimates an optimum ignition timing of each of cylinders from the relationship between the phase angle (Tmax) at which the torque peaks and the phase angle (Pmax) at which the in-cylinder pressure peaks with respect to the ignition timing of the cylinder.

There is a problem of a difficulty in estimating the temporal change of the MBT for each of cylinders with light calculation load and high accuracy. An object of the present invention is to provide a control device capable of detecting a temporal change in the fuel efficiency optimum ignition timing (MBT) for each of cylinders. Therefore, the control device for internal combustion engine includes a control unit (CPU) that estimates an optimum ignition timing of each of cylinders from the relationship between the phase angle (Tmax) at which the torque peaks and the phase angle (Pmax) at which the in-cylinder pressure peaks with respect to the ignition timing of the cylinder.

An eccentric member for a system for varying compression ratio of an internal combustion engine comprises two circumferential bearing portions for bearing respective big ends of connecting rods of a V-type internal combustion engine. The bearing portions are eccentric with respect to an inner surface of the eccentric member and located at a distance from each other in axial direction of the eccentric member. The eccentric member also comprises two external gears between which the bearing portions are located. The eccentric member is made of two half-sleeves which are fixed to each other at least between the bearing portions.

An eccentric member for a system for varying compression ratio of an internal combustion engine comprises two circumferential bearing portions for bearing respective big ends of connecting rods of a V-type internal combustion engine. The bearing portions are eccentric with respect to an inner surface of the eccentric member and located at a distance from each other in axial direction of the eccentric member. The eccentric member also comprises two external gears between which the bearing portions are located. The eccentric member is made of two half-sleeves which are fixed to each other at least between the bearing portions.

A method is provided for producing an assembly of an eccentric rod (15, 16) and a piston (20, 21) of a connecting rod of an internal combustion engine having an adjustable compression ratio. The method includes providing an eccentric rod (15, 16) having a first end (36, 37) for attachment to an eccentric lever of an eccentric adjusting device of the connecting rod and a second end (38, 39) for attachment to a piston (20, 21) that can be guided in a hydraulic chamber of the connecting rod. The method then includes arranging the second end (38, 39) of the eccentric rod (15, 16) in the piston (20, 21); introducing an injection-molding tool (47) into the piston (20, 21); and injection-molding a circumferentially closed retaining ring (43) between the piston (20, 21), the second end (38, 39) of the eccentric rod (15, 16) and the injection-molding tool (47).

A method is provided for producing an assembly of an eccentric rod (15, 16) and a piston (20, 21) of a connecting rod of an internal combustion engine having an adjustable compression ratio. The method includes providing an eccentric rod (15, 16) having a first end (36, 37) for attachment to an eccentric lever of an eccentric adjusting device of the connecting rod and a second end (38, 39) for attachment to a piston (20, 21) that can be guided in a hydraulic chamber of the connecting rod. The method then includes arranging the second end (38, 39) of the eccentric rod (15, 16) in the piston (20, 21); introducing an injection-molding tool (47) into the piston (20, 21); and injection-molding a circumferentially closed retaining ring (43) between the piston (20, 21), the second end (38, 39) of the eccentric rod (15, 16) and the injection-molding tool (47).

A device for controlling the compression rate of a variable compression ratio engine comprises: an actuating cylinder comprising a piston defining two chambers for receiving a pressure fluid, a pressure accumulator supplying the pressure fluid, a first fluid circuit connecting the upper chamber to the accumulator and comprising a first valve assembly for controlling the flow of the fluid in the first fluid circuit, and a second fluid circuit connecting the lower chamber to the accumulator and comprising a second valve assembly for controlling the flow of a fluid in the second fluid circuit. At least one of the fluid circuits comprises a bypass conduit arranged so as to connect one of the chambers to the accumulator. The bypass conduit comprises a non-return valve.