| 摘要 |
A system for controlling the air-fuel ratio for an internal combustion engine having a detector for detecting the concentration of a constituent of exhaust gases passing through the exhaust passage, air-fuel mixture supply device for supplying an air fuel mixture to the induction passage, electromagnetic valves for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply device, a comparator for comparing the output signal of the detector with respect to a predetermined value, an integrating circuit having a proportional circuit for integrating the output of the comparator, a driving circuit for driving the electromagnetic valves in dependency upon the output signal of the integrating circuit. The system has a throttle valve switch actuated by the operation of the throttle valve in an idling condition, steady state and full load condition of the engine and a vacuum switch actuated by vacuum pressure in the induction passage of the engine when the throttle valve is opened to a predetermined degree. A switching circuit is provided to change the proportional constant and integrating constant of the integrating circuit and a decision circuit is provided to actuate the switching circuit in dependency on signals from the throttle valve switch and the vacuum switch, whereby the proportional constant and integrating constant may be changed according to the engine operation.
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