US Patent 7950623 Valve opening and closing control apparatus

When a control unit variably controls an electric power supplied to an electric motor to repeat a valve opening and closing movement of a valve between a first intermediate position and a second intermediate position through a neutral position, the control unit initially sets the neutral position as a control target value until a valve position, which is sensed with a valve opening degree sensor, is located immediately before the neutral position. The control unit thereafter changes the control target value to the first intermediate position or the second intermediate position when the control unit determines that the valve position, which is sensed with the valve opening degree sensor, reaches the neutral position.