Valve gear for engine

Abstract

A valve gear includes a camshaft, a first cam and a second cam that drive an intake valve or an exhaust valve, and a synchronous cam that rotates in synchronism with the first and second cams. The valve gear includes a rocker shaft, a rocker arm, and a cam follower swingably supported by the rocker shaft and that comes into contact with the synchronous cam. The valve gear includes a thruster that converts the swinging motion of the cam follower into a thrust and moves the rocker arm to a first side or a second side in the axial direction. The valve gear makes the camshaft compact, and also increases the reliability of operation at high rotations and reduces an operation sound at low rotations.

1 - 4 . (canceled) 
     
     
         5 : A valve gear for an engine comprising:
 a camshaft rotatably supported by a cylinder head;   a first cam on the camshaft that drives one of an intake valve and an exhaust valve;   a second cam on the camshaft spaced apart from the first cam in an axial direction, and that drives the other of the intake valve and the exhaust valve, the second cam including a cam profile different from a cam profile of the first cam;   a synchronous cam on the camshaft that rotates in synchronism with the first cam and the second cam;   a rocker shaft parallel or substantially parallel to the camshaft;   a rocker arm supported by the rocker shaft to swing and move in the axial direction and to convert a rotation of one of the first cam and the second cam into a reciprocal motion and transmit the reciprocal motion to one of the intake valve and the exhaust valve;   a cam follower swingably supported by the rocker shaft and that comes into contact with the synchronous cam; and   a thruster that converts a swinging motion of the cam follower into a thrust in the axial direction and moves the rocker arm to one of a first side and a second side in the axial direction.   
     
     
         6 : The valve gear for the engine according to  claim 5 , wherein the thruster includes:
 a slide portion that swings integrally with the cam follower and moves in the axial direction integrally with the rocker arm; and   a switching portion supported by the cylinder head and including a first switch and a second switch, wherein the first switch and the second switch selectively come into contact with the slide portion; and   the slide portion includes:   a first inclined cam surface that receives a force at a first side thereof in the axial direction, wherein the force is generated by one of the first switch and the second switch in contact with the first inclined cam surface; and   a second inclined cam surface that receives a force at a second side thereof in the axial direction, wherein the force is generated by the other of the first switch and the second switch in contact with the second inclined cam surface.   
     
     
         7 : The valve gear for the engine according to  claim 6 , wherein the cam follower cannot move in the axial direction; and
 the slide portion is separate from the cam follower and is movable in the axial direction relative to the cam follower.   
     
     
         8 : The valve gear for the engine according to  claim 6 , wherein each of the first switch and the second switch includes a pin that moves between an advancing position such that a first end of the pin comes into contact with the slide portion and a retreating position at which the first end of the pin separates from the slide portion;
 a second end of the pin abuts against a pin cam of a moving member that moves in a direction perpendicular or substantially perpendicular to a direction in which the pin moves; and   the pin cam has a shape such that when the moving member moves to a first side, the first switch moves to the advancing position and the second switch moves to the retreating position, and when the moving member moves to a second side, the first switch moves to the retreating position and the second switch moves to the advancing position.