Variable valve timing system in an engine having a rotating cam-shaft

Abstract

A variable valve timing system includes a first timing member driven by the engine, a second timing member rotatably fixed to the crankshaft, a helical device engaged between the first and second timing members and including a piston movable for adjusting an angular position between the first and second timing members, a hydraulic circuit device for selectively applying a hydraulic pressure to the piston for selectively moving the piston to adjust the angular position, and a damper device on the first and second timing members for hydraulically damping rotational vibrations between the first timing member and the second timing member. The damper device includes the first timing member, a ring-member engaged with the second timing member and a viscous fluid between the first timing member and the ring-member.