Variable valve timing control device for internal combustion engine

A variable valve timing control device of an internal combustion engine, comprising:

• a hydraulic drive type variable valve timing device that changes a rotation phase of a camshaft, which is referred to as a camshaft phase, with respect to a crankshaft of an internal combustion engine and adjusts a valve timing;
• a lock mechanism that includes a lock pin movable between a lock position for locking the camshaft phase at a predetermined lock phase and a lock release position for releasing lock of the camshaft phase;
• a hydraulic control valve that controls an oil pressure that drives the variable valve timing device and the lock mechanism;
• and
• a control unit that switches a control mode of the hydraulic control valve among a timing advancing mode for supplying a hydraulic oil to a timing advance chamber of the variable valve timing device and advancing the camshaft phase, a timing retarding mode for supplying the hydraulic oil to a timing retard chamber of the variable valve timing device and retarding the camshaft phase, a holding mode for holding the oil pressure of the timing advance chamber and the timing retard chamber and holding the camshaft phase, a locking mode for releasing the oil pressure of an oil pressure chamber of the lock mechanism and moving the lock pin to the lock position, and a filling mode for filling a space, which is referred to as a back space, formed by movement of the lock pint to the lock position with the hydraulic oil, wherein
• the control unit executes a locking time filling control of switching the control mode to the filling mode and filling the back space with the hydraulic oil in a state the control mode is switched to the locking mode and the lock pin is moved to the lock position, and thereafter returning the control mode to the locking mode when a lock demand of the camshaft phase occurs.