The disclosure concerns a method for vibration reduction in a compression ignition four- stroke internal combustion engine. The internal combustion engine comprises exhaust and intake valves controlled by exhaust and intake camshafts. The method comprises, when operating the internal combustion engine below a threshold rotational speed, steps of: changing a timing of the exhaust camshaft to advance closing of the exhaust valve, and - changing a timing of the intake camshaft to delay opening of the intake valve.

An engine variable camshaft timing (VCT) phaser assembly is equipped in an internal combustion engine (ICE) to adjust the rotation of the engine's camshaft relative to the engine's crankshaft. The adjustments advance and retard the opening and closing movements of the engine's intake and exhaust valves. An electric motor and a planetary gear set work together amid use of the VCT phaser assembly. The planetary gear set can include two or more ring gears, planet gears, and a sun gear. A backlash condition sometimes experienced in previous VCTs is minimized in the VCT phaser assembly by one or more springs that urge the planet gears into engagement with the ring gears.

A camless valve control system for an internal combustion engine in disclosed. The system includes a hydraulic distributor, having a rotating distributor shaft timed to the operation of the engine, the rotating distributor shaft comprising an internal flow dividing plug channeling an internal hydraulic flow to first and second portions of the rotating distributor shaft; an opening control ring oriented coaxially with the rotating distributor shaft with at least one hole configured to cyclically align with the rotating distributor shaft and provide opening hydraulic control to open a controlled valve, and a closing control ring oriented coaxially with the rotating distributor shaft with at least one hole configured to cyclically align with the rotating distributor shaft and provide closing hydraulic control to close the controlled valve.

A reciprocating exhaust valve for a two-stroke internal combustion engine has a shaft for connection to a valve actuator, the shaft defining a reciprocation axis of the valve, the reciprocation axis defining a longitudinal direction of the valve; and a blade having: a first end having an arcuate edge, a second end connected to the shaft, two side portions, and a central portion. The blade has a first end portion adjacent the first end that includes a part of the central portion and of each of the two side portions. A width of the central portion is greater than a width of each of the side portions. In the first end portion, a thickness of the part of each of the two side portions is greater than a thickness of the part of the central portion.

A reciprocating exhaust valve for a two-stroke internal combustion engine has a shaft for connection to a valve actuator, the shaft defining a reciprocation axis of the valve, the reciprocation axis defining a longitudinal direction of the valve; and a blade having: a first end having an arcuate edge, a second end connected to the shaft, two side portions, and a central portion. The blade has a first end portion adjacent the first end that includes a part of the central portion and of each of the two side portions. A width of the central portion is greater than a width of each of the side portions. In the first end portion, a thickness of the part of each of the two side portions is greater than a thickness of the part of the central portion.

An exhaust valve system for a two-stroke internal combustion engine having: at least one exhaust valve movable between open and closed positions; an actuator for moving the at least one exhaust valve; a valve position sensor; a controller communicating with the actuator and the valve position sensor. The controller being programmed for: controlling the actuator to attempt to move the at least one exhaust valve to a desired one of the open and closed positions; determining if the at least one exhaust valve has failed to reach the desired position based on the position of the at least one exhaust valve sensed by the valve position sensor; and controlling the actuator to move the at least one exhaust valve to an intermediate position when the at least one exhaust valve has failed to reach the desired position.

An exhaust valve assembly for a two-stroke internal combustion engine has a housing adapted for connection to an engine block of the two-stroke internal combustion engine; an electric actuator having an electric motor, the electric motor being disposed in the housing; and at least one reciprocating exhaust valve operatively connected to the electric actuator. The at least one exhaust valve is linearly movable by the electric motor. A portion of the at least one exhaust valve is disposed in the housing.

A synchronous belt drive system having: a synchronous belt with a tensile cord of high-modulus fiber such as glass, carbon, PBO, or aramid; a driver sprocket and at least one driven sprocket, at least one of which is an obround sprocket; and a tensioner having: a base having a cylindrical portion extending axially with a radially outer surface and a receiving portion, an eccentric arm pivotally engaged with the radially outer surface, a torsion spring disposed within the receiving portion, the torsion spring applying a biasing force to the eccentric arm, and a pulley journalled to the eccentric arm. Preferably, no one of the eccentric arm, pulley, or torsion spring is axially displaced along an axis A-A from the others. The obround sprocket has a toothed surface and at least one linear portion disposed between two arcuate portions having a constant radius, the linear portion having a predetermined length.

A drive-side rotor is rotated synchronously with a crankshaft. A driven-side rotor is rotated integrally with a camshaft. An internal gear section is formed at the driven-side rotor. An Oldham coupling includes: a driven Oldham flange that is formed at the drive-side rotor; a drive Oldham flange that is formed at the planetary rotor; and an Oldham intermediate that is configured to synchronize rotation of the driven Oldham flange and rotation of the drive Oldham flange while permitting eccentricity between the driven Oldham flange and the drive Oldham flange. There is satisfied a relationship of θ2<θ1 where: θ1 is a maximum tilt amount of the planetary rotor relative to the driven Oldham flange; and θ2 is a maximum tilt amount of the planetary rotor in a clearance formed at the Oldham coupling.

A continuously variable valve duration apparatus includes a camshaft, a cam unit on which a cam is formed, a guide bracket including an upper guide boss, an internal wheel configured to transmit rotation of the camshaft to the cam unit, a wheel housing in which the internal wheel is rotatably inserted, wherein a guide thread is formed in a portion of the wheel housing, and of which a guide shaft is formed to be movably inserted into the upper guide boss, a worm wheel to which an internal thread engaging with the guide thread is formed in the worm wheel, and to which an external thread is formed thereon, a control shaft on which a control worm engaged with the external thread is formed, and an upper bushing mounted on a lower portion of the upper guide boss to support the guide shaft.