A motor drive device for valve timing control of an internal combustion engine includes: a motor drive unit that controls a phase of a camshaft to drive a motor for controlling opening and closing operation of a valve; and a determination unit that determines whether a timing is to start up the motor or to normally drive the motor. The motor drive unit drives the motor with an advance angle when it is determined that the timing is to normally drive the motor by the determination unit, and the motor drive unit normally drives the motor without the advance angle when it is determined that the timing is to start up the motor.

A control shaft of a cam shaft adjustment unit has axially spaced adjustment cams, which are designed in a first axial section of the control shaft for a continuous operation of a cylinder and in a second axial section for a cylinder shut-off. The adjustment cams for the continuous operation of a cylinder have, over the entire circumference of the cam circle, a radial extension which is greater than a zero stroke extension and the adjustment cams for the cylinder shut-off have, around their circumference, a shut-off section of the cam circle with a radial extension which is less than or equal to the zero stroke extension. The control shaft has a stop that reduces the rotation in both circumferential directions and functions as the calibration point for an engine electronics system.

A variable valve timing device applied to an engine system may include a rotor supplied with oil and rotated in clockwise and counterclockwise directions, one-way clutches coupled to the rotor to limit an amount of rotation of the rotor, a sprocket having a rotor hole surrounding an external diameter portion of the rotor, a rotation shaft fitted into a shaft hole of the rotor for the supply of oil to oil grooves, and a shaft fixing member coupled to the rotation shaft to fix the rotor and the rotation shaft, wherein the one-way clutches restrict clockwise/counterclockwise rotation of the rotor by torque of a camshaft, achieving an improvement in fuel efficiency/emission material (EM) of an engine.

Methods and systems are provided for controlling a variable camshaft timing system. In one example, a method may include actuating a camshaft phaser with a camshaft duty cycle determined based on a sampled camshaft position and an estimated camshaft position, the estimated camshaft position determined based on a previously determined camshaft duty cycle.

A modified rocker assembly having an offset end is designed for engine heads having an obstruction preventing use of a symmetric switching rocker arm. The modified rocker assembly has an obstructed side and a non-obstructed side and has an outer structure with a first end, and an inner rocker structure fitting within the outer structure, the inner structure also having a first end. The modified rocker assembly has an axle pivotally connecting the first ends of inner structure to the outer structure, such that the inner structure pivots within the outer structure around the axle. At least one torsion spring on one side of the axle rotationally biases the inner structure relative to the outer structure. The outer structure is offset on the obstructed side as it extends from the second end toward the first end, creating the first offset portion to provide additional clearance on the obstructed side.

A variable cam timing system in an engine is provided. The variable cam timing system includes a camshaft receiving rotational input from a crankshaft. The camshaft includes a valve cam rotationally actuating a valve coupled to a cylinder and a null cam actuating a null follower including a null spring exerting a return force on the null cam during interaction between the null cam and the null follower, where the null follower is independent from the cylinder.

A variable cam timing system in an engine is provided. The variable cam timing system includes a camshaft receiving rotational input from a crankshaft. The camshaft includes a valve cam rotationally actuating a valve coupled to a cylinder and a null cam actuating a null follower including a null spring exerting a return force on the null cam during interaction between the null cam and the null follower, where the null follower is independent from the cylinder.

An actuating system of an engine valve comprises a movable member, for example, in the form of a master piston controlled by a cam of a camshaft. A slave piston is hydraulically controlled by the master piston by means of a volume of pressurized fluid, to open said engine valve against the action of a return spring. The system also comprises an auxiliary device for applying an additional force to the engine valve to keep the engine valve in a closed position. The auxiliary device is configured or controlled in such a way that the total force tending to keep the engine valve in its closed position varies during each rotation cycle of the cam. The total force is higher at least in one part of the rotation cycle of the cam wherein the engine valve must remain in its closed position, and is, instead, reduced at least in one part of the rotation cycle of the cam wherein the engine valve is not in its closed position.

The present disclosure provides systems and methods to compensate for backlash within a cam phasing system. For example, compensating for backlash by commanding a predetermined amount of additional actuator movement to account for backlash within a cam phaser. According to some aspects, a spring is provided within a cam phaser to unidirectionally take up the backlash within the cam phasing system.

To provide a control device capable of calculating a cam phase equal to an actual cam angle even when a corresponding cam angle signal detection range is exceeded by changing a cam phase by a variable valve mechanism. In addition to the conventional cam angle measuring function, a cam angle measuring means for advancing or retarding beyond a cam angle measurement reference position, and a means for determining that the cam angle signal advances or retards beyond the cam angle measurement reference position are provided. By switching the cam angle measuring function according to a determination result as to whether the cam angle signal exceeds the cam angle measurement reference position, it is possible to improve the time resolution of the angle measurement while maintaining the cam phase change amount at the same wide angle as the conventional one.