| 摘要 |
PROBLEM TO BE SOLVED: To suitably suppress instability of an engine speed in idling operation due to a change-over of an engine combustion mode in an internal combustion engine changing over the engine combustion mode between a normal combustion mode and a temperature raising combustion mode. SOLUTION: The engine 10 changes the engine combustion mode between a stoichiometric combustion mode of controlling an air-fuel ratio of each cylinder #1-#4 in a stoichiometric air-fuel ratio, and the temperature raising combustion mode of controlling an air-fuel ratio of a part of the cylinders #1-#4 in a richer side than the stoichiometric air-fuel ratio and controlling air-fuel ratios of other cylinders in leaner sides than the stoichiometric air-fuel ratio on the basis of a temperature raising request of an NOx catalyst 22. An electronic controller 50 controls an opening of a throttle valve 21 so that an actual engine speed in idling matches a target engine speed. The electronic controller 50 learns an ISC learning controlled variable for neutralizing a dissociating trend of the target engine speed and the actual engine speed per each combustion mode individually, and it changes the ISC learning controlled variables in response to each combustion mode. COPYRIGHT: (C)2004,JPO
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