Patent ID: 8297240

Claim:
A variable valve timing control apparatus for an internal combustion engine having a crankshaft and a camshaft, comprising: a hydraulic variable valve timing device 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; an intermediate lock mechanism configured to lock the VCT phase at an intermediate lock position located between a full retard position and a full advance position of an adjustable range of the VCT phase; an oil pressure control device configured to control oil pressure that actuates the variable valve timing device and the intermediate lock mechanism, wherein the oil pressure control device causes the intermediate lock mechanism to lock the VCT phase at the intermediate lock position when rotation of the internal combustion engine is to be stopped; intermediate lock position learning means for learning the intermediate lock position as a reference phase to obtain a learning value of the intermediate lock position when the intermediate lock mechanism locks the VCT phase at the intermediate lock position; actual VCT phase computing means for computing an actual VCT phase based on the learning value of the intermediate lock position; target VCT phase computing means for computing a target VCT phase in accordance with an operational condition of the internal combustion engine based on the learning value of the intermediate lock position; and variable valve timing controlling means for controlling a control amount of the oil pressure control device such that the actual VCT phase becomes the target VCT phase.