| 摘要 |
An air-fuel ratio controller for an internal combustion engine with a catalytic converter in an exhaust passage has an air-fuel ratio sensor, an engine sensor, and a control unit. The air-fuel ratio sensor produces a signal indicative of an air-fuel ratio of an exhaust gas in the exhaust passage on an upstream side of the catalytic converter. The engine sensor produces a signal indicative of misfiring of the engine. The control unit is operatively coupled to the air-fuel ratio sensor and the engine sensor. The control unit computes an estimated quantity of oxygen to be stored in the catalytic converter based on the signal from the air-fuel ratio sensor, and determines if the engine is misfiring based on the signal from the engine sensor. The control unit also produces an estimated adjustment value and adjusts an air-fuel ratio of intake air based on the estimated adjustment value such that the estimated quantity of oxygen to be stored substantially coincides with a predetermined target quantity of oxygen to be stored. However, when misfiring is determined based on the signal from the engine sensor, the computation of the estimated quantity of oxygen to be stored is stopped or not used, and a predetermined value is used to control the air-fuel ratio of intake air. With the air-fuel ratio controller of the present invention, influence of misfiring on air-fuel ratio control can be reduced.
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