Patent ID: 8215272
Filing Date: 2012-07-10
Classification: F01L

Abstract:
1. A variable valve timing control apparatus for an internal combustion engine having a camshaft and a crankshaft, the variable valve timing control apparatus comprising: a hydraulic variable valve timing device configured to adjust valve timing by changing a 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 between a full retard position and a full advance position within 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 lock pin; a lock control unit configured to control the oil pressure control device to execute a lock control, in which the lock pin is displaced in a lock direction to lock the VCT phase at the intermediate lock position when a lock request is generated; and a rotational speed detector configured to detect a rotational speed of the internal combustion engine, wherein: the oil pressure control device has a hydraulic control valve that integrally includes: the oil pressure control device is operated under the following operational modes based on a control amount of the oil pressure control device: the lock control unit controls the oil pressure control device to shift the VCT phase in a direction opposite from a VCT phase shift direction if the VCT phase is located on the lock-mode VCT phase shift direction side of the intermediate lock position when the rotational speed of the internal combustion engine becomes equal to or less than a first rotational speed that is lower than a target idle rotation speed during a stop of rotation of the internal combustion engine; and the lock control unit controls the oil pressure control device to allow the lock pin to be displaced in the lock direction if the VCT phase is not located on the lock-mode VCT phase shift direction side of the intermediate lock position when the rotational speed of the internal combustion engine becomes equal to or less than the first rotational speed during the stop of the rotation.