Valve mechanism for an internal combustion engine

Claim 1

A valve mechanism for an internal combustion engine having at least one intake valve and at least one exhaust valve, a cam shaft having a low-speed cam and a high-speed cam, a low-speed rocker arm operatively connected to said at least one of said valves and a high-speed rocker arm which are rocked by the cams to operate the at least one valve, changeover means for connecting the low-speed rocker arm and the high-speed rocker arm with each other so as to be rocked together by the high-speed cam, an improvement of the mechanism comprises: a base circle of said low-speed cam having a larger diameter than that of the base circle of the high-speed cam; a roller follower rotatably mounted on a shaft provided in the low-speed rocker arm, a part of a peripheral portion of the roller follower being projected from the low-speed rocker arm to be engaged with the low-speed cam; said high-speed rocker arm having a slipper engaging with the high-speed cam; and said changeover means comprising a piston slidably mounted in said high-speed rocker arm and means for pushing the piston so as to connect the high-speed rocker arm with the low-speed rocker arm.