| 摘要 |
PROBLEM TO BE SOLVED: To quickly materialize temperature rise of a catalyst by controlling combustion air fuel ratio at the time of request for catalyst warming up. SOLUTION: In an internal combustion engine controlling combustion air fuel ratio in a combustion chamber to rich and supplying secondary air to an exhaust gas passage at a time of request of catalyst warming up, it is judged whether an exhaust gas air fuel ratio sensor detecting exhaust gas air fuel ratio at a position on an upstream side of catalyst and on a downstream side of a secondary air supply position in an exhaust gas passage is active or inactive, combustion air fuel ratio is open-controlled to first combustion air fuel ratio KAP1 enabling stable combustion between theoretical air fuel ratio and flammable limit air fuel ratio richer than theoretical air fuel ratio (S7-S9) when the exhaust gas air fuel ratio sensor is inactive at a time of request of catalyst warming up (S2), and combustion air fuel ratio is feedback-controlled to second combustion air fuel ratio KAP2 richer than the first combustion air fuel ratio KAP1 and near flammable limit air fuel ratio (S10, S13-S18) while estimating combustion air fuel ratio in the combustion chamber based on exhaust gas air fuel ratio detected by an exhaust gas air fuel ratio sensor when the exhaust gas air fuel ratio sensor is active. COPYRIGHT: (C)2007,JPO&INPIT
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