Adjustable valve train for an internal combustion engine, and engine and motorcycle incorporating same

摘要

A valve train for an internal combustion engine includes a camshaft, a valve-operating cam for operating an engine valve, and a link mechanism for swinging the valve-operating cam. The valve train also includes a holder member operable to turn around the camshaft, and a drive mechanism operable to turn the holder member for varying positions of the link mechanism. The drive mechanism includes a ball screw provided perpendicularly to the camshaft, a slider threadably engaged with the ball screw, an arm member swingably attached to the slider, and a connecting bolt having one end secured to an arm-connecting portion of the arm member, and the other end secured to the holder member. In such movable valve train for an internal combustion engine, the holder member and the drive mechanism are connected to each other with a small and lightweight configuration, requiring a minimal number of parts.