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.

A variable valve timing assembly includes an electric motor; a first set of gears driven by the electric motor; a first set of grooves and ball bearings driven by the first set of gears; a second set of grooves and ball bearings driven by the first of grooves and ball bearings; wherein the first set of grooves and ball bearings converts rotational movement of the first set of gears to axial rotational movement of the first set of ball bearings; wherein the axial movement of the first set of ball bearings causes rotational movement of the second set of grooves; whereby the rotational movement of the second set of grooves enables rotation of a camshaft engaged to a valve.

A cam phaser is described for selectively engaging in a torque transmitting mode or an angle control mode. In the torque transmitting mode, torque from a camshaft is transmitted to an e-motor, which functions as a generator and provides electrical energy.

An electrically-controlled variable camshaft timing (VCT) system including a sun gear, having an inner axial surface, configured to communicate torque from an output shaft of an electric motor to a gearbox assembly; and a collet sleeve having at least one slot configured to engage the output shaft of the electric motor and a relief section permitting radial-inward compression and an outer axial surface that releasably engages the inner axial surface of the sun gear such that the outer axial surface of the collet sleeve is engaged with the inner axial surface of the sun gear while an amount of torque applied to the sun gear by the output shaft is below a predetermined torque threshold and the sun gear and the collet sleeve are angularly displaced relative to each other when an amount of torque applied to the sun gear by the output shaft is at or above the predetermined torque threshold.

A continuous variable valve duration apparatus includes: a camshaft, a front cam unit and a rear cam unit of which the phase relative to the camshaft can be varied, a front inner wheel and a rear inner wheel, a front guide bracket and a rear guide bracket, a front wheel housing and a rear wheel housing, a front control shaft, a rear control shaft, a phase controller selectively changing the relative phase of the front control shaft and the rear control shaft, a main driving unit for driving the rear control shaft, vibration sensors that measure the vibration of each cylinder corresponding to the front cam unit and the rear cam unit and output a corresponding signal, and a controller for controlling the operation of the main driving unit and the phase controller according to the output signals of the respective vibration sensors.

An electrically-actuated variable camshaft timing (VCT) phaser assembly, comprises a sun gear configured to receive input from an electric motor and one or more planet gears having radially-outwardly-extending gear teeth that engage the sun gear; a first ring gear, having radially-inwardly extending gear teeth that engage the radially-outwardly-extending gear teeth of the sun gear, configured to receive rotational output provided by a crankshaft; a second ring gear, having radially-inwardly extending gear teeth that engage the radially-outwardly-extending gear teeth of the sun gear, configured to couple to a camshaft; one or more planet gear pins that carry the planet gear(s) and engage a planetary gear set to prevent the relative rotation of the planet gear pin(s) relative to the planetary gear set; and one or more springs that bias the planet gear pin(s) and the planetary gear(s) toward the first ring gear and the second ring gear.

An electrically-actuated variable camshaft timing (VCT) device, comprising: an input configured to receive rotational force from an electric motor; an output configured to couple with a camshaft of an internal combustion engine; a planet gear having radially outwardly extending gear teeth configured to engage ring gears and a radially-inwardly-facing surface; a planet pin, supporting the planet gear, having an outer surface and an axis of rotation about which the planet gear rotates; and a spring applying force in a substantially axial direction along the axis of rotation that moves the planet gear in a radial direction.

A method includes determining a value of an operational motor current limit and setting a value of a startup current limit equal to a predetermined value in excess of the value of the operational motor current limit if a set of predetermined conditions is satisfied. The method includes determining that operation of the engine has been interrupted, operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the startup current limit after determining that operation of the engine has been interrupted, determining that operation of the engine has resumed, and operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the operational motor current limit after determining that operation of the engine has resumed.

A variable valve timing assembly includes an electric motor; a first set of gears driven by the electric motor; a first set of grooves and ball bearings driven by the first set of gears; a second set of grooves and ball bearings driven by the first of grooves and ball bearings; wherein the first set of grooves and ball bearings converts rotational movement of the first set of gears to axial rotational movement of the first set of ball bearings; wherein the axial movement of the first set of ball bearings causes rotational movement of the second set of grooves; whereby the rotational movement of the second set of grooves enables rotation of a camshaft engaged to a valve.

The valve timing control unit includes a valve timing control mechanism that includes a driving rotary body, a driven rotary body, an electric motor and a deceleration gear each for setting the relative rotational phase of the driving rotary body and the driven rotary body, and a phase sensor unit that detects the actual phase of the driving rotary body and the driven rotary body. The valve timing control unit includes a controller that controls the electric motor to reduce a phase difference between the actual phase and a target phase, and the controller includes a swing controller that swings the target phase in vicinity of the target phase when the target phase is maintained and the actual phase having a fluctuation amount is held in a holding region, in which the fluctuation amount is less than a preset value.