| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device for an internal combustion engine, for suppressing the worsening of exhaust emission even when disturbance occurs after learning determined to be converged is restricted. Ž<P>SOLUTION: The internal combustion engine 10 has a plurality of cylinder groups (a first bank 11 and a second bank 12). In each cylinder group, an air-fuel ratio feedback control system is provided including a catalyst 18, a main air-fuel ratio sensor 20 and a sub oxygen sensor 22. When the learning of sub feedback control is determined to be converged, subsequent learning is restricted. When the learning is determined to be converged in each cylinder group, a predetermined index value for one cylinder group, calculated in accordance with the output of the sub oxygen sensor 22, is compared with that for the other. When a difference between the index value for one cylinder group and that for the other exceeds a predetermined value, the restriction of the learning is cancelled. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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