Patent ID: 7434554

Claim:
A controller for a vane-type variable valve timing adjusting mechanism in which each of a plurality of vane accommodating chambers formed in a housing of the vane-type variable valve timing adjusting mechanism is divided into two chambers, an advance hydraulic chamber and a retard hydraulic chamber, by a vane, the controller comprising: a hydraulic control valve for controlling a hydraulic pressure in the advance hydraulic chamber and a hydraulic pressure in the retard hydraulic chamber; and a control means for controlling an electric current applied to the hydraulic control valve in accordance with a deviation between a target displacement angle and an actual displacement angle of the variable valve timing adjusting mechanism, wherein: the control means performs pulse-current application control to apply pulse current to the hydraulic control valve to drive the variable valve timing adjusting mechanism in a direction of a target displacement angle, and further comprising: a one-way valve disposed in each of hydraulic supply passages of the advance hydraulic chamber and the retard hydraulic chamber in at least one of the vane accommodating chambers for preventing a reverse flow of operating oil from the hydraulic chamber; a drain oil passage disposed in parallel to the hydraulic supply passage of each of the hydraulic chambers for bypassing the one-way valve; a drain switching valve disposed in the drain oil passage and driven by a hydraulic pressure; and a hydraulic switching valve switching the hydraulic pressure to drive the drain switching valve, wherein: when an advance operation of the variable valve timing adjusting mechanism is performed, the control means controls the hydraulic switching valve to close the drain switching valve for the advance hydraulic chamber into which the operating oil flows and to open the drain switching valve for the retard hydraulic chamber from which the operating oil is discharged; and when a retard operation of the variable valve timing adjusting mechanism is performed, the control means controls the hydraulic switching valve to close the drain switching valve for the retard hydraulic chamber into which the operating oil flows and to open the drain switching valve for the advance hydraulic chamber from which the operating oil is discharged.