Valve performance control apparatus for internal combustion engines

Abstract

A valve performance control apparatus has a low speed cam, a high speed cam, and an intermediate speed cam. A rocker arm is arranged between the cams and a valve. The rocker arm contacts the low speed cam. A pair of cam followers are reciprocally supported in the rocker arm to contact the high speed and intermediate speed cams. Lock members are slidably received in bores (or grooves) of the rocker arm. The lock members, when positioned in an unlocked position, permit the free reciprocation of the associated cam followers with respect to the rocker arm, which causes the valve to be driven by the low speed cam. When locked, the lock members abut against the associated cam followers and lock the cam followers to the rocker arm, which causes the valve to be driven by the cam with the largest profile. The lock member has an abutment surface, which contacts and is pressed by the cam follower. The bore has a supporting wall for supporting the lock member opposite to the abutment surface when the abutment surface of the lock member is positioned in the lock position and is pressed by the cam follower. The lock member is not subjected to bending or shear, which improves the reliability of the apparatus.