Patent ID: 6532922
Filing Date: 2003-03-18
Classification: F01L

Abstract:
A variable valve timing control device comprising:a housing member provided on a drive train for transmitting a driving force from a crankshaft of an internal combustion engine to a camshaft for opening and closing an intake valve and an exhaust valve of the internal combustion engine for being unitarily rotated with the crankshaft or the camshaft; a rotor member relatively rotatably assembled in the housing member to form a hydraulic pressure chamber with the housing member, the rotor member having a vane portion dividing the hydraulic pressure chamber into an advanced angle hydraulic chamber and a retarded angle hydraulic chamber; a relative rotation control mechanism allowing relative rotation between the housing member and the rotor member by performing an unlocking operation through supply of an operation fluid and restricting relative rotation between the housing member and the rotor member at an intermediate phase position between a most advanced angle phase position and a most retarded angle phase position through discharge of the operation fluid; a hydraulic pressure circuit controlling the supply and discharge of the operation fluid with respect to the advanced angle hydraulic chamber and the retarded angle hydraulic chamber and controlling the supply and discharge of the operation fluid with respect to the relative rotation control mechanism; a control valve provided in the hydraulic pressure circuit, the control valve discharging the operation fluid from the advanced angle hydraulic chamber and the retarded angle hydraulic chamber and from the relative rotation control mechanism; the control valve including a variable electromagnetic spool valve having different exhaust opening widths at a both drain function region in which the operation fluid is discharged from the advanced angle hydraulic chamber and the retarded angle hydraulic chamber and having a larger opening for a passage in communication with the retarded angle hydraulic chamber or the advanced angle hydraulic chamber whose volume is relatively large at idling of the internal combustion engine.