Patent ID: 6874456

Claim:
A valve operating apparatus of an internal combustion engine for causing an engine valve to open and close, comprising: a drive shaft having an oil passage formed therein; a drive cam, which is integrally fixed to an outer periphery of the drive shaft and whose axis is eccentric to an axis of the drive shaft; a link arm formed at one end with a bore rotatably fitted onto an outer peripheral surface of the drive cam; a rocker arm having a first armed portion that is rotatably fitted to the other end of the link arm via a pivotally linked portion between the link arm and the rocker arm, and a second armed portion through which the engine valve is opened and closed by oscillating motion of the rocker arm; a lubricating system comprising: (a) a first communicating passage formed in the drive cam and having a first opening end communicating the oil passage formed in the drive shaft; and (b) a second communicating passage formed in the link arm and having a first opening end opening to an inner peripheral surface of the bore of the link arm for proper fluid communication with a second opening end of the first communicating passage, and having a second opening end opening to the pivotally linked portion between the link arm and the rocker arm; and a clearance space defined between the outer peripheral surface of the drive cam and the inner peripheral surface of the bore of the link arm is formed as a crescent-shaped clearance except an area of maximum loading during rotary motion of the drive cam.