Rocker arm mechanism in overhead cam type engine

Claim 1

A rocker arm mechanism in an OHC type engine; an intake valve, an exhaust valve, and a cam shaft comprising: a cam rotatable while interlocking with said cam shaft; and a rocker arm which oscillates in accordance with the rotation of said cam so as to open and close one of said intake valve and said exhaust valve, wherein said rocker arm further comprises a rocker arm body and a pad member rotatably fitted to said rocker arm body for contacting said cam, said cam and said pad member being brought into contact with each other such that said pad member may rotate due to a frictional force generated between said cam and said pad member as said cam rotates, wherein said contact of said pad member to said cam is eccentrically located with respect to a center of rotation of said pad member; said pad member further comprises a shaft portion and a substantially half-spherical cam receiving portion integrally formed with one end of said shaft portion, said rocker arm body includes a shaft hole bored therein orthogonal to said cam shaft, and said shaft portion is rotatably supported in said shaft hole; and wherein said cam further comprises a curved surface parallel to said cam shaft, a tapered surface continuously formed with said curved surface and a joint formed between said curved surface and said tapered surface which contacts with said flat portion of said cam receiving member such that said cam and said pad member may be brought into point-contact with each other.