| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control device for performing an air-fuel ratio feedback control based on feedback gains for each catalyst part properly set, in an internal combustion engine having a plurality of catalysts (catalyst parts) arranged in series with an exhaust passage. SOLUTION: Over-and-short amount of oxygen in exhaust gas flowing out of first to third catalysts 53 to 55 constituting a catalyst device are calculated, by using a catalyst model in consideration of oxygen occlusion reaction in the catalysts. The feedback gains (proportional gains) of the first to third catalysts 53 to 55 are set to become larger, as a position of the catalyst is nearer to downstream of the exhaust passage. Feedback controlled variables for each catalyst are calculated based on values calculated by multiplying each feedback gain to the over-and-short amount of oxygen. Air-fuel mixture supplied to an engine is feedback-controlled, so that feedback controlled variables for the catalyst device, calculated by summing up the feedback control variables for the catalysts, becomes "0". COPYRIGHT: (C)2004,JPO&NCIPI
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