| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the following problems: an oxygen sensor is slow in reaction in an operating condition immediately after the oxygen sensor is activated, a delay period is lengthened during warm-up operation having a small control gain set based on engine operating condition, and when delay time for determining a change in an air-fuel ratio is changed based on the control gain at that time immediately after the oxygen sensor is activated, a control cycle is lengthened and the air-fuel ratio deviates from a target air-fuel ratio. <P>SOLUTION: This air-fuel ratio control method for an internal combustion engine controls the air-fuel ratio by using an air-fuel ratio correction constant set based on the output of the oxygen sensor after detecting that the oxygen sensor is activated, in the internal combustion engine including a catalyst provided in an exhaust passage and the oxygen sensor provided upstream of the catalyst. Elapsed time is timed soon after detecting that the oxygen sensor is activated (S1). Until the timed elapsed time reaches a predetermined time until the oxygen sensor is sufficiently activated, the air-fuel ratio correction constant is adjusted in a direction to accelerate response of air-fuel ratio control after determination of the air-fuel ratio. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
