SOHC-type valve operating system in internal combustion engine.

摘要

An SOHC-type valve operating system in an internal combustion engine having a single cam shaft commonly provided for a pair of intake valves (16) and a pair of exhaust valves (20). A plurality of intake valve driving members (271) are rockably disposed between the cam shaft and the pair of intake valves (16) and have an operative-connection switchover mechanism for switching over the connection and disconnection of the intake valve driving members (271). A pair of exhaust valve driving members (272) are rockably disposed between the cam shaft and the pair of exhaust valves (20) and independently operate each of the exhaust valves (20). The operative-connection switchover mechanism includes a switchover pin movable between a position for operatively connecting adjacent intake valve driving members (271) and a position for releasing such connection, which pin is slidably mounted in a cylindrical sleeve secured to the intake valve driving members for guiding the movement of the switchover pin. The cylindrical sleeve also rotatably supports a cylindrical rotor (45,46,47,48) in rolling contact with a cam (29,30,31,32) provided on the cam shaft. The operative-connection switchover mechanism is disposed on the opposite side of the intake valves (16) with respect to the rocking axis (37) of the intake valve driving member (271) whereby space for disposing a component such as an ignition plug (79) is available on the intake side of the engine. <IMAGE>