Abstract: Feedback control is carried out to maintain the rotational speed of an internal combustion engine during idling at a desirable speed determined according to the operating conditions of the engine by controlling an adjusting valve for controlling the amount of air to be fed to the engine. The actual rotational speed of the engine and the actual opening angle of the throttle valve are detected and when the actual rotational speed is lower than a predetermined value and at the same time the actual opening angle of the throttle valve is smaller than a predetermined value, the feedback control is carried out. Further, whether or not the driving power of the engine is operatively transmitted to the driving wheels is detected, and the predetermined value for the rotational speed of the engine is set at a higher value when the driving power is not transmitted to the driving wheels than when the driving power is transmitted to the driving wheels.

Abstract: A fuel supply system for an internal combustion engine having at least one combustion chamber comprises a supercharger, a fuel intake passage system leading from a source of air to the combustion chamber through the supercharger. A portion of the fuel intake passage system between the supercharger and the combustion chamber is divided into first and second intake passages having incorporated therein primary and secondary throttle valves. The primary throttle valve is operatively associated with a foot-operated acceleration pedal whereas the secondary throttle is adapted to be controlled by a pressure developed inside the fuel intake passage system at a position downstream of the throttle valves. A diaphragm valve unit is utilized to control the secondary throttle valve in response to the pressure inside the fuel intake passage system at that position.

Abstract: An exhaust gas purifying system for an automobile engine including at least first and second engine cylinder has a shutter valve for interrupting the supply of a combustible air-fuel mixture to the first engine cylinder during a particular engine operating condition, a three-way electromagnetically operated valve for controlling the operation of the shutter valve, and a secondary air supply unit including a switching valve for selectively supplying a secondary air to a portion of an exhaust passage upstream of at least one catalyst unit disposed in the exhaust passage.