Valve timing adjuster

Abstract

A valve timing adjuster according to the present invention, comprises a pulley rotationally connected to one of an output shaft of engine and a cam shaft, a sleeve which is supported on the pulley, which is rotatable within a predetermined angle of rotation on the pulley and which is rotationally connected to the other one of the output shaft of engine and the cam shaft, an electromagnet mounted on one of the pulley and the sleeve, an armature mounted on the other one of the pulley and the sleeve so that magnetic flux including a magnetic flux component extending in the circumferential direction of the valve timing adjuster is generated, the armature is drawn by the magnetic flux toward the electromagnet and the sleeve is rotated within the predetermined angle of rotation on the pulley when the electromagnet is energized, and a control device which controls the operation of electromagnet so that the phase difference between the cam shaft and the output shaft is suitably adjusted during operation of a vehicle. Since the valve timing adjuster according to the present invention does not need means for converting an axial movement of the pulley to a circumferential or rotational movement thereof, does not have many friction regions and does not have the hydraulically-operated actuator and the hydraulic pipe lines, the durability and response speed are increased and the cost of modification of engine is not needed.