VALVE OPERATING SYSTEM IN INTERNAL COMBUSTION ENGINE

摘要

A valve operating system in an internal combustion engine includes a cam shaft provided with a valve operating cam, a rocker arm having a pair of support wall portions which are integrally connected at their base ends to a swinging support portion swingably supported on a support member mounted on a cylinder head and which are opposed to each other at a distance in a direction along the swinging axis of the swinging support portion, a support shaft supported between the support wall portions, and a roller which is rotatably supported on the support shaft with a bearing interposed therebetween so as to be in rolling contact with the valve operating cam. A lower connecting wall interconnecting lower portions of the base ends of the support wall portions is projectingly provided on the swinging support portion in a manner opposed to an outer peripheral surface of a lower portion of the roller. Thus, it is possible to increase the rigidity of the rocker arm, while avoiding an increase in size of the rocker arm.