| 摘要 |
PROBLEM TO BE SOLVED: To keep exhaust emission excellent even in performing a rich control after fuel cut in an air-fuel ratio control device for an internal combustion engine. SOLUTION: In an exhaust passage 14 of an internal combustion engine 10, a main air-fuel ratio sensor 42 is arranged on the upstream side of a catalyst 40, and a sub oxygen sensor 44 is arranged on the downstream side of the catalyst 40. Main feedback control of the air-fuel ratio is performed according to the output of the main air-fuel ratio sensor 42, and sub feedback control of the air-fuel ratio is performed according to the output of the sub oxygen sensor 44. Also, after performing the fuel cut of the internal combustion engine 10 and performing the rich control, an air-fuel ratio dither control alternately reversing the air-fuel ratio between the rich side and lean side is performed. Further, while the air-fuel ratio dither control is performed, operation of the sub feedback control is stopped or inhibited to avoid interference with the dither control. COPYRIGHT: (C)2009,JPO&INPIT
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