Device for controlling the idling operation of an internal combustion

Abstract

A device for controlling idling operation of an internal combustion engine comprising an actuator operatively connected to a throttle valve for controlling the opening degree of the throttle valve during engine idling operation, an actuator position sensor for sensing an operating position of the actuator, a first control unit adapted to receive output signals from an engine RPM sensor, a water temperature sensor which senses the temperature of engine cooling water and the actuator position sensor to control the operation of the actuator such that the opening degree of the throttle valve is adjusted to an appropriate level to maintain the RPMs of the engine during idling at a predetermined value corresponding to the sensed temperature of the cooling water, and a second control unit independently operated from said first control unit to control the operation of the actuator in accordance with the operating position of the actuator and the temperature of the cooling water so as to limit the operating position of the actuator and thereby limit the RPMs of the engine to the predetermined value corresponding to the sensed temperature of the cooling water notwithstanding a higher value of RPMs being called for by the first control unit. As a result, abnormal increases in RPMs during the idling operation of the engine are prevented even when the first control unit malfunctions.