| 摘要 |
PURPOSE:To restrain the hunting of air-fuel ratio and prevent the deterioration in exhaust cleaning performance by increasing an increasing/reducing quantity in an integral control in accordance with the changing quantity per unit time of the density of an exhaust gas ingredient while fixing said increasing/reducing quantity to a defined value when a low load is detected. CONSTITUTION:When an engine 5 is operated, it is judged by a control circuit 20 whether an air-fuel ratio feedback control condition is satisfied or not and, when judged yes, a reference current value is retrieved in accordance with the outputs of an absolute pressure sensor 10 and a crank angle sensor 11. And, the output of an O2 sensor 14 is compared with a reference value corresponding to a target air-fuel ratio, and a integral control for increasing or reducing an air-fuel ratio controlling value is carried out in accordance with the compared result. In this case, the increasing/ reducing quantity per defined period in the integral control is increased in accordance with the changing quantity per unit time of the detected value of oxygen density detected by the O2 sensor 14. Also, when the low load condition of the engine is detected, the increasing/reducing quantity per defined period in an integral control is fixed to a defined value.
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