| 摘要 |
PURPOSE:To suppress hunting of air-fuel ratio in transient operation so as to improve exhaust gas cleaning performance of the engine in the caption, by computing predicted values of the pressure in an intake pipe and/or the rotating speed of an engine and determining a proportional value or a integrated value according to said predicted values to increase or decrease the control value for air-fuel ratio. CONSTITUTION:During an engine 5 is in operation, a control circuit 20 reads signals from an absolute pressure sensor 10, a crack angle sensor 11, an oxigen concentration sensor 14, and other sensors and computes predicted absolute pressure and predicted rotational speed of said engine 1 and then determines whether the oxigen concentration is leaner than the standard concentration which corresponds to the intended air-fuel ratio or not. It the case is judged that the air-fuel ratio is changed from being rich to lean, a proportional value is determined computing from the predicted absolute pressure, the predicted speed, and a standard proportional value. While, if it is judged that the air-fuel ratio will stay lean continuingly, an integrated value is computed in the same way as the above. A air-fuel ratio correction factor is then corrected corresponding to the result of the computation, and the air-fuel ratio is controlled by controlling a linear type solenoid valve 9 according to the corrected correction factor.
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