Patent ID: 7913658

Claim:
An engine valve actuating mechanism, comprising: a cylinder head having a plurality of valves mounted therein for reciprocal movement thereof; a camshaft rotatably mounted in the cylinder head, the camshaft including a first cam and a second cam for selective alternating use in operation of one of the valves; a rocker arm shaft having a rocker arm supported thereon, the rocker arm shaft arranged parallel to the camshaft such that the rocker arm is pivotally movable about the axis of the rocker arm shaft, and is also movable in an axial direction of the rocker arm shaft so as to be selectively movable either to a first operation position, at which the rocker arm is brought into contact with the first cam, or to a second operation position at which the rocker arm is brought into contact with the second cam; a first rocker arm moving mechanism for moving the rocker arm from the first operation position to the second operation position; a second rocker arm moving mechanism for moving the rocker arm from the second operation position to the first operation position, and a trigger member which is pivotally supported on the cylinder head for selectively restricting axial movement of the rocker arm in response to a rocking state of the rocker arm, wherein each of the rocker arm and the trigger member includes a rocker-side key portion and a trigger-side key portion, the rocker-side key portion and the trigger-side portion being capable of being brought into contact with each other in the axial direction; wherein the respective key portions are configured to increase or decrease contact margins thereof in the axial direction in response to the rocking state of the rocker arm and to eliminate the contact margin thereof when the engine valve is closed; and wherein during engine operation, the rocker arm is brought into contact with a selected one of the cams in response to rotation of the camshaft to operably open or close the valve, thus allowing the valve actuating mechanism to selectively use either the first cam or the second cam for operating the valve.