| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent the deterioration of emission by promoting the warmup of a catalyst by properly controlling an air-fuel ratio, when starting an internal combustion engine which uses alcohol-containing fuel. Ž<P>SOLUTION: In an air-fuel control device, when requiring the warmup of the catalyst of the internal combustion engine, an air-fuel ratio control means controls the air-fuel ratio to be lean over a predetermined lean control time. The warmup of the catalyst is promoted by raising a combustion temperature by maintaining the air-fuel ratio to be lean. Here, a lean control time is set long as an alcohol concentration in fuel becomes high. Thus, the warmup of the catalyst can be promoted without deteriorating the exhaustion of NOx. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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