Patent ID: 7107951

Claim:
A variable valve timing control device of an internal combustion engine for controlling a variable valve timing device which varies valve timing of intake valves or exhaust valves driven to open and close by a camshaft by varying a rotation phase of the camshaft (hereinafter, referred to as “camshaft phase”) with respect to a crankshaft of the internal combustion engine, said variable valve timing device comprising: a first rotating member disposed concentrically with said camshaft and rotationally driven by rotary drive power from said crankshaft; a second rotating member that rotates integrally with said camshaft; a phase-varying member that transmits rotary power from said first rotating member to said second rotating member and varies rotation phase of said second rotating member with respect to said first rotating member; and a motor disposed concentrically with said camshaft so as to control the rotation phase of this phase-varying member, wherein said variable valve timing device is constructed so that when said valve timing is not to be changed a speed of said motor is matched to a speed of said camshaft to match a turning speed of said phase-varying member to the speed of said camshaft and thereby hold a difference in rotation phase between said first rotating member and said second rotating member steady and thus hold said camshaft phase steady, and when said valve timing is to be changed the speed of said motor is changed with respect to the speed of said camshaft to change the turning speed of said phase-varying member with respect to the speed of said camshaft and thereby vary the difference in rotation phase between said first rotating member and said second rotating member and thus vary said camshaft phase, said variable valve timing control device comprising: required valve timing change rate calculating means for calculating a required valve timing change rate on a basis of a deviation between a target valve timing and an actual valve timing; required speed difference calculating means for calculating a required speed difference between said motor and said camshaft on a basis of said required valve timing change rate; and motor control value calculating means for calculating a motor control value so as to control a speed difference between said motor and said camshaft to said required speed difference.