| 摘要 |
A variable valve control apparatus includes an oscillating arm and a pivot lever pivotably mounted to each other via a swivel joint. A first roller, which is rotatably mounted on an arm of the pivot lever engages with the camming surface of a cam, while a second roller which is rotatably mounted on another arm of the pivot lever makes contact with a contact surface of an arcuate sliding block disposed within a housing of the valve control apparatus. The contact surface of the sliding block includes a first region which has an arcuate contour, and a radius that is centered on a pivot axis of the swivel joint when the valve is in the closed position, as well as a second region which adjoins the first region and has a curved spur that extends inwardly toward the swivel joint. The sliding block is slidable along an arcuate path between a first position in which the second roller engages the first region of the contact surface and a second position in which it engages the second region of the contact surface, so that, when the sliding block is in the first position, the pivot joint remains stationary, and the valve remains closed. When the sliding block is in the second position, the second roller engages with the spur, so that camming movement of the first roller actuates the valve to an open position. |
