US Patent 7603971 Valve operating mechanism

A valve operating mechanism for an internal combustion engine includes a drive member that engages a control arm at a contact point spaced apart from the pivot axis of the control arm, and a control member that operates to vary the contact point in order to vary a spacing between the contact point and the pivot axis of the control arm to vary the amplitude of reciprocation of a cam surface of the control arm and to vary the portion of the cam surface which is engaged by a cam follower member during pivoting of the control arm to thereby vary the amount of lift and/or opening duration of the engine valve.