An internal combustion engine comprises a crankshaft, at least one camshaft adjustable electromechanically by an actuating gearing, an engine control unit, and a camshaft control unit for controlling an actuating motor which operates the actuating gearing. The engine control unit is linked to a device for detecting the angular position of the crankshaft, and the camshaft control unit is linked to the engine control unit. A device for detecting a reference position of the camshaft and a device for detecting the angular position of the shaft of the actuating motor are provided as sole mechanisms for detecting the angular position of the camshaft. The camshaft control unit is designed to determine the phase angle of the camshaft in relation to the crankshaft on the basis of the information items provided by said devices in combination with the detected angular position of the crankshaft and the transmission ratio of the actuating gearing.

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 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.

An electromechanical camshaft phaser (3) comprises a setting gear (4) and an electric motor (5), which is controlled by means of an electric-motor control unit (6). Data concerning the operation of the electric motor (5) including position changes of its motor shaft are transferred via a data bus (8) from the electric-motor control unit (6) to an engine control unit (7) of the internal combustion engine (1) comprising the camshaft phaser (3). In addition, recurring time signals are transferred from the electric-motor control unit (6) to the engine control unit (7) via a separate line (9), by which harder real-time requirements are met than by the data bus (8). The time signals are used to generate a time difference signal in the engine control unit (7) by comparison with the data received by the engine control unit (7), which time difference signal is fed back to the electric-motor control unit (6) via the data bus (8) and is used there to synchronize the electric-motor control unit (6) with the engine control unit (7).

In a variable valve control device, a variable valve control system and a method for controlling a variable valve mechanism according to the present invention, An ECM (201) transmits a phase detection value (RA1) computed based on a crank angle signal (CRANK) and a cam angle signal (CAM) to a VTC control unit (202) via a communication network (211), and VTC control unit (202) computes a phase detection value (RA2) based on a motor angle signal (MAS), controls a variable valve timing mechanism (114) based on phase detection value (RA2) in the transient state of an internal combustion engine, and controls variable valve timing mechanism (114) based on phase detection value (RA1) in the steady state of the internal combustion engine.

When an EDU determines that a motor is in a control unstable state where the motor cannot be controlled to a target rotation speed due to a drive voltage output duty value being smaller than a threshold value, the EDU performs a control point shifting operation to shift a control point between a first control point, which is in the control unstable state, and a second control point, which is a control stable state outside the control unstable state. Thus, even when the motor is in a stepping rotation state, it is possible to control the target rotation speed regardless of influence of a cogging torque, and appropriately control the cam phase of the intake camshaft to a target phase when the engine is stopped.

A valve timing adjusting device adjusts an opening/closing timing of a first valve driven by a rotation of a first camshaft and an opening/closing timing of a second valve driven by a rotation of a second camshaft. The valve timing adjusting device includes a first driving circuit controlling a first motor configured to generate a torque to shift a rotation phase of the first camshaft and a second driving circuit controlling a second motor configured to generate a torque to shift a rotation phase of the second camshaft. A first switching element of the first driving circuit operates at a switching frequency that is different from that of a second switching element of the second driving circuit.

An electrically-actuated variable camshaft timing (VCT) phaser is employed for use with an internal combustion engine (ICE). The electrically-actuated VCT phaser includes a gear set assembly and a fixture. The gear set assembly has an input gear and an output gear, among other possible components. The input gear receives rotational drive input from an engine crankshaft, and the output gear transmits rotational drive output to an engine camshaft. The fixture is secured in the gear set assembly. Amid installation of the electrically-actuated VCT phaser on the ICE, the fixture constrains rotational movement of the gear set assembly. After installation, the fixture can be removed from the gear set assembly.