| 摘要 |
A valve timing control device includes a rotatable shaft, a housing including a timing wheel axially immovable but angularly movable with respect to the rotatable shaft, a piston disposed coaxially with the rotatable shaft and the timing wheel, a hydraulic chamber for applying a hydraulic pressure to move the piston axially, a servovalve disposed between the hydraulic pressure chamber and hydraulic pressure supply and release passages and comprising a sleeve and a spool, an actuator for axially moving the spool, and a phase adjusting mechanism operatively coupling the piston, the housing, and the rotatable shaft for varying angular relationship between the timing wheel and the rotatable shaft in response to axial movement of the piston. The actuator may be a hydraulic actuator or an electric actuator. The phase adjusting mechanism may comprise roller pins mounted on the piston and rollingly fitted in a guide groove defined in the rotatable shaft and a guide slot defined in the housing, or meshing helical teeth on the piston, the housing, and the rotatable shaft. |
