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.

For example, two intake valves for each cylinder each are driven by a selected one of cams via a corresponding rocker arm. Each rocker arm includes a support portion and a pressing portion (distal end portion). The support portion is rockably supported by a cylinder head. The pressing portion is configured to press a stem of the corresponding intake valve. The support portion of one of the rocker arms deviates to one side in an axis X direction (cam axial direction) with respect to the distal end portion. The support portion of the other one of the rocker arms deviates to the other side in the axis X direction with respect to the distal end portion.

In starting the engine, if it is determined that large cams are not completely prepared for all driving cams, valve closing timings of all intake valves are changed by driving the VVT so that all of the cylinders have equal in-cylinder filling efficiency. A fuel injection amount of each cylinder is determined by a feedforward control assuming that the large cams are completely prepared for all of the driving cams. When the valve closing timing of all of the intake valves are changed by driving the VVT to equalize the in-cylinder filling efficiencies of all of the cylinders, all of the cylinders have substantially equal in-cylinder air-fuel ratios.

A slider control module, based on a mode command: selectively extends pins into one or more slider actuators of a camshaft slider. Contact between the pins and the grooves in the slider actuator(s) during rotation of a camshaft slides the camshaft slider axially along the intake camshaft. An actual mode module: determines a last stored indicator of the mode command; commands the slider control module to extend one of the pins to slide the camshaft slider and achieve the last stored indicator of the mode command; and, based on whether the one of the pins extended in response to the command, indicates that an actual mode is either: (i) the last stored indicator of the mode command; or (ii) another mode. The mode command module updates the mode command to the actual mode.

A camshaft module may include a module body in which at least one camshaft for controlling valves for a charge cycle of an internal combustion engine is accommodated. The camshaft may comprise a support shaft and sliding cam pieces that are accommodated on the support shaft so as to be displaceable in an axial direction of the support shaft. A support element may also be provided on which actuators for the axial displacement of the sliding cam pieces are accommodated. The support element may extend in the axial direction and therefore parallel to the support shaft. In some cases, a coefficient of thermal expansion of the support element substantially corresponds to a coefficient of thermal expansion of the support shaft.

The present invention relates to an adjusting element for the axial displacement of a camshaft, supported displaceably along an axis of the camshaft, or a camshaft section arranged displaceably on a shaft along the axis of the camshaft, with the adjusting element being mobile between a first position and a second position, the adjusting element showing a guide section by which one or more projections of a camshaft, supported in an axially displaceable fashion, or a camshaft section, supported in an axially displaceable fashion, can cooperate in the first position such that the camshaft or the camshaft section can be axially displaced by a rotation about the axis of the camshaft, and the projection does not cooperate with the guide section in the second position. Furthermore, the invention relates to a device which comprises an axially displaceable camshaft, which shows one or more projections and such an adjusting element.

A cam follower for operable attachment to a valve lifter assembly for use with a variable cam lobe camshaft in a variable valve timing system includes a housing with a central cavity and a mushroom head with a stem pivotably connected to the housing in the central cavity, the mushroom head having a radiused surface for contacting a cam lobe surface. The cam follower is used in combination with a variable cam surface of an axially displaceable camshaft to obtain improvements in idling speed and volumetric efficiency.

Valve trains employing a splined interface between phaser(s) and a concentric camshaft, actuator at rear of camshaft actuated by an actuation rod, adding a clearance hole to the lobe pin for clearance to the actuation rod, supplying oil to camshaft bearings via the concentric camshaft inner tube, and bolt on front camshaft bearing. The valve trains may further employ a third rocker lever that is usable for a selectable valve event (e.g. compression release brake) while also implementing variable valve timing and a concentric camshaft.

A continuous variable valve duration apparatus includes a camshaft, a plurality of wheels mounted to the camshaft, of which a wheel key is formed thereto respectively, a plurality of cam portions of which a cam and a cam key are formed thereto respectively, of which the camshaft is inserted thereto, of which relative phase angle with respect to the camshaft is variable, a plurality of inner brackets connected with the each wheel key and the each cam key, a slider housing of which the each inner bracket is rotatably inserted thereto, and rotatably configured around a hinge bracket connected to a cylinder head and a control portion selectively moving the slider housings to change relative position of a rotation center of the inner brackets.

A slider control module, based on a mode command: selectively extends pins into one or more slider actuators of a camshaft slider. Contact between the pins and the grooves in the slider actuator(s) during rotation of a camshaft slides the camshaft slider axially along the intake camshaft. An actual mode module: determines a last stored indicator of the mode command; commands the slider control module to extend one of the pins to slide the camshaft slider and achieve the last stored indicator of the mode command; and, based on whether the one of the pins extended in response to the command, indicates that an actual mode is either: (i) the last stored indicator of the mode command; or (ii) another mode. The mode command module updates the mode command to the actual mode.