| 摘要 |
A control system for the fuel/air ratio of an internal combustion engine is provided, having an intake duct, an exhaust pipe, a feed device for the fuel/air mixture, an electromagnetic ON/OFF valve for correcting the fuel/air ratio of the fuel/air mixture which is fed by the feed device for the fuel/air mixture, a circuit for producing a periodic jitter signal with a pattern, a displacement control circuit for displacing the level of the centre of the jitter signal, a drive circuit for producing a drive output in accordance with the jitter signal and an O2 measuring sensor for detecting the oxygen concentration in the exhaust gases flowing through the exhaust pipe. The control system comprises a device for detecting the transition state of the engine mode and a control circuit with an integration circuit which is connected to the O2 measuring sensor and a circuit for producing square-wave pulses in accordance with the integration output of the integration circuit for driving the electromagnetic valve. In addition, a switching device is provided which, with reference to the output signal of the device which perceives the transition state, closes the circuit from the O2 measuring sensor to the drive circuit via the control circuit and interrupts the circuit from the O2 measuring sensor to the drive circuit via the displacement control circuit. Therefore, during a transition state, the fuel/air ratio is controlled by the integration output signal of the control circuit so that the fuel/air ratio can be quickly adjusted to the stoichiometric fuel/air ratio.
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