| 摘要 |
<p>PROBLEM TO BE SOLVED: To further improve accuracy of air-fuel ratio control by preventing excessive correction of a fuel injection amount.SOLUTION: In air-fuel ratio feedback control referring to an output signal of an air-fuel ratio sensor provided at an upstream of a catalyst for exhaust emission control, the output signal of the air-fuel ratio sensor is compared with a target value corresponding to a target air-fuel ratio, it is determined whether the present air-fuel ratio is leaner or richer than the target air-fuel ratio according to a magnitude relationship, and while the present air-fuel ratio is determined to be leaner than the target air-fuel ratio, a correction amount is changed so as to gradually increase a fuel injection amount, and while the present air-fuel ratio is determined to be richer than the target air-fuel ratio, the correction amount is changed so as to gradually decrease the fuel injection amount. Then, when the output signal of the air-fuel ratio sensor changes so as to traverse the target value, determination is performed after waiting for elapse of delay time, a change amount of the correction amount per unit time in the delay time is made to be smaller than the change amount of the correction amount per unit time outside of the delay time.</p> |
