| 摘要 |
<P>PROBLEM TO BE SOLVED: To perform feedback control of an air-fuel ratio at least based on a time integral value calculated from deviation of a catalyst upstream air-fuel ratio sensor output value from a target value, so as not to unnecessarily and excessively correct the air-fuel ratio. <P>SOLUTION: An exhaust emission control device calculates feedback controlled variables DFi for correcting a corrected reference fuel injection amount Fbase to perform the air-fuel ratio feedback control, based on an expression DFi=Gp×DFc+Gi×(OSAall-(Cmaxall/2)). Deviation DFc of a fuel supply amount in a cylinder is controlled to become zero by a proportional Gp×DFc, balance of deviation of an air-fuel ratio abyfs that flows into a first catalyst 53 from a stoichiometric air-fuel ratio is controlled to become zero and an oxygen occlusion amount OSAall of the first catalyst 53 is controlled to become a target oxygen occlusion amount (half of maximum oxygen occlusion amount Cmaxall), by an integral term Gi×(OSAall-(Cmaxall/2))limited within a predetermined range value. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
