Patent ID: 8261704

Claim:
A variable valve timing control apparatus for an internal combustion engine that has: a crankshaft; a camshaft; a hydraulic variable valve timing unit configured to adjust valve timing by changing a variable cam timing (VCT) phase that is a rotational phase of the camshaft relative to the crankshaft; a lock pin configured to lock the VCT phase at an intermediate lock position located within an adjustable range of the VCT phase; and a hydraulic control valve configured to control oil pressure that actuates the variable valve timing unit and the lock pin, the variable valve timing control apparatus comprising: VCT control means for switching a control, based on an operational state, between (a) a VCT phase control for controlling the VCT phase to a target phase and (b) a lock pin projection control for allowing the lock pin to project; and foreign object release control means for executing, when an abnormality occurs, a foreign object release control for changing a control amount of the hydraulic control valve based on a predetermined pattern, wherein the foreign object release control means changes the predetermined pattern depending on the abnormality in the execution of the foreign object release control.