Patent ID: 8220426

Claim:
A valve timing control device in an internal combustion engine, the valve timing control device for controlling valve timing of at least one of an intake valve and an exhaust valve opened/closed by a cam shaft through torque transmission from a crank shaft, the valve timing control device comprising: an electric motor including a motor shaft, the electric motor generating a magnetic retaining torque and a motor torque in the motor shaft based on a power supply supplied thereto; a control unit coupled to the electric motor and controlling the motor torque by controlling the power supply supplied to the electric motor; and a phase control mechanism coupled to the cam shaft and the motor shaft, the phase control mechanism transmitting a cam torque alternating between a positive and a negative direction in response to rotation of the cam shaft to the motor shaft and controlling a relative phase between the crank shaft and the cam shaft in accordance with a torque balance in the motor shaft, wherein: the control unit includes: engine determining means for determining an operating state of the internal combustion engine; and power supply control means for performing control of the power supply supplied to the electric motor, the power supply control means stopping the power supply supplied to the electric motor after an amount of the power supply supplied to the electric motor is first reduced and then increased when the engine determining means makes an engine stop determination.