US Patent 7302923 Variable valve timing device adapted for internal combustion engine

A variable valve timing device includes a cam shaft, a rocker arm rotatably supporting the first roller and enabling a valve to be opened by a swing movement thereof when a first roller is pressed, a swing cam with a second cam surface, and an actuator for controlling the support shaft to move along a circular arc with a center at a center of the first roller in a valve-open state. The swing cam is swingable at a center of the support shaft, when a second roller is pressed by the cam shaft, so that the second cam surface presses the first roller. A contact position, between the first cam surface and the second roller, moves in a direction opposite to a rotational direction of the cam shaft when the support shaft is moved in a direction where a maximum lift amount of the valve becomes smaller.