Patent ID: 6758176
Filing Date: 2004-07-06
Classification: F01L,F02D,Y02T

Abstract:
A valve timing control apparatus for an internal combustion engine, comprising:a cam phase actuator including a first rotor capable of rotating in synchronism with a crank shaft of an internal combustion engine, a second rotor fixedly mounted on a cam shaft for opening and closing an intake valve or alternatively an exhaust valve of said internal combustion engine, and a lock mechanism for locking said second rotor to said first rotor at a first relative angle; an oil pump for generating a hydraulic pressure for said internal combustion engine; arithmetic means for arithmetically determining a current value corresponding to a hydraulic pressure for releasing a locked state at said first relative angle to thereby shift said first relative angle to a second relative angle; and hydraulic pressure regulating means for supplying a hydraulic pressure for regulating a cam phase of said second rotor in dependence on said current value, wherein oil pressure is supplied to only one of the advancing side or the retarding side of said actuator in order to release said lock mechanism, and wherein said arithmetic means is so designed as to arithmetically determine said first current value on the basis of a hold current value for holding said cam phase actuator at said second relative angle, said first current value is set to the value offset by a predetermined amount with said hold current as a reference in a direction incapable of releasing said lock mechanism.