| 摘要 |
PROBLEM TO BE SOLVED: To reconcile improvement of drivability and reduction of emission in an internal combustion engine controlling O2 storage amount in catalyst to fixed amount by a feedback control using an air-fuel ratio sensor. SOLUTION: When gain to be used in an air-fuel ratio(A/F) feedback control routine is set to a large value, A/F hunting is generated after a transient state and drivability is deteriorated (curve C1). When gain is set to a small value, an A/F fluctuation width is reduced and as a result, emission is increased (curve C2). In this case, when an engine operation state is in the transient state, gain is set to the large value, a feedback correction is performed for A/F, gain is set to the small value for deviation of A/F generated as a result and the feedback control is performed for A/F.
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