Valve Timing Changing Apparatus

摘要

A valve timing changing apparatus according to the present invention includes: a housing rotor; a vane rotor; an advancement path which communicates with an advancement chamber and through which a hydraulic oil passes; a retardation path which communicates with a retardation chamber and through which the hydraulic oil passes; and a lock mechanism which locks the vane rotor at an intermediate position with respect to the housing rotor and whose locked state is released by hydraulic pressure of the hydraulic oil, the lock mechanism includes: an advancement lock bar and a retardation lock bar each of which oscillates about a predetermined oscillation center within a vertical plane vertical to a rotation axis; an advancement restriction spring; and a retardation restriction spring, and the center of gravity of each of the advancement lock bar and the retardation lock bar is positioned so as to produce centrifugal force in a direction to maintain the locked state in an entire oscillation range.