Abstract: A restraining hole for restraining a stopper piston is constituted by a straight hole having an axis perpendicular to the direction of a relative rotation of a vane rotor with respect to a shoe housing and a tapered hole formed on a deep side of the straight hole and reduced in diameter on a deep side thereof. According to this construction, by virtue of a wedge effect between the tapered hole and the stopper piston, a relative rotation between a driving shaft system and a driven shaft system can be restrained at a predetermined angular position and it is possible to suppress the occurrence of a striking sound.

Abstract: A restraining hole for restraining a stopper piston is constituted by a straight hole having an axis perpendicular to the direction of a relative rotation of a vane rotor with respect to a shoe housing and a tapered hole formed on a deep side of the straight hole and reduced in diameter on a deep side thereof. According to this construction, by virtue of a wedge effect between the tapered hole and the stopper piston, a relative rotation between a driving shaft system and a driven shaft system can be restrained at a predetermined angular position and it is possible to suppress the occurrence of a striking sound.

Abstract: A seal plate partitions a sectorial space which houses a vane and a circumferential groove which houses a torsion spring, so that the sectorial space is formed to prevent the communication between an advance angle pressure chamber and a retard angle pressure chamber regardless of the space of the circumferential groove. As a result, by setting the inner diameter of the vane smaller than the outer diameter of the torsion spring, the outer diameter of the vane can be made relatively small without lowering the engine performance. Therefore, it is possible to reduce the actuator in size without lowering the engine performance, to reduce the weight of a valve timing adjusting device and to obtain a mounting space easily for mounting the valve timing adjusting device on the engine.

Abstract: According to the present invention, in a valve timing adjustment device, an arc-shaped gears are assembled alternately on a piston in the peripheral direction. A spring biases an annular member and the arc-shaped gear in the direction as to be away from the piston. A pin is press-fitted into a retainer ring. A spring biases the arc-shaped gear toward the retainer ring, that is, in the direction as to be closer to the piston. An annular member, an annular groove, the head of the pin, a cap, and a containing hole function as a hydraulic damper, respectively. Accordingly, the collision speed of the annular member with the piston accompanied by the movement of the arc-shaped gears, and the piston and the collision speed of the head of the pin with the piston are slowed down. In this way, the respective collision noises can be reduced.