| 摘要 |
PURPOSE:To prevent an air-fuel ratio from greatly fluctuating from a set value, by interrupting a feedback correction of the air-fuel ratio based on a integration processing when an output from an O2 sensor exceeds continuously a set value for discriminating an abnormal condition. CONSTITUTION:A comparator 32 compares an output from an O2 sensor applied thereto with a prescribed value. The output from the comparator 32 is subjected to the integration process by an integrator 30 as well as to the proportional process by a proportional amplifier 31 and the outputs from them are combined by an adder 33 to be an air-fuel ratio feedback control signal. On the other hand, the output from the O2 sensor is compared with the set values corresponding the maximum value and the minimum value and when it keeps the maximum value or the minimum value for a period linger than a prescribed period, an interruption signal is issued for closing a contact 34a and opening a contact 34b. As a result, the integrator 30 has a gain of zero and an output from the proportional amplifier 31 is not applied to the adder 33 for interrupting a feedback control of an air-fuel ratio.
|
