Valve timing regulation apparatus for engine

摘要

For enhancing engine startability and reducing discharge of unburned fuel from an engine, a camshaft is rotated toward the most advance side when an exhaust valve is opened. In one aspect, the camshaft is urged toward the advance side with respect to a timing pulley by the urging force of a spring. A stopper is received displaceably in a diametrical direction in a receiving hole and is fitted in a stopper hole when the camshaft is at the most advance position. In another aspect, at engine starting where operating fluid is not supplied to a release fluid chamber, a clutch piston is coupled to a front plate by a spring, and gear teeth of the front plate and the clutch piston are engaged with each other.