Rotational phase adjusting apparatus

摘要

In a rotational phase adjusting apparatus which may be used for adjusting valve timing of an engine, a stopper piston is set engageably into and disengageably from a tapered hole of a shoe housing so that relative pivotal motion between the shoe housing and a vane rotor is constrained at the most retarted position. A hydraulic pressure chamber communicates with a retard-side hydraulic pressure chamber while a hydraulic pressure chamber communicates with an advance-side hydraulic pressure chamber. A pressurized area of the stopper piston receiving hydraulic pressure from the hydraulic pressure chamber in a direction of releasing constraint is set to be larger than a pressurized area of the stopper piston receiving hydraulic pressure from the hydraulic pressure chamber in the direction of releasing constraint. When working oil is supplied to the advance-side hydraulic pressure chamber from a state where the stopper piston is fitted into the tapered hole, the stopper piston is drawn out from the tapered hole assuredly even in the case of low hydraulic pressure.