| 摘要 |
PROBLEM TO BE SOLVED: To reduce concern about increase in emissions of carbon monoxide and hydrocarbon during rich injection.SOLUTION: Combustion gas discharged from an internal combustion engine 12 is supplied to a catalyst 52 via an exhaust passage 34. When fuel injection to the internal combustion engine 12 is temporarily stopped due to a fuel cut function, the amount of oxygen occluded in the catalyst 52 is increased. Rich injection is executed after the fuel cut is completed to make the amount of oxygen occluded in the catalyst 52 appropriate. An engine ECU 60 determines the degree of deterioration of the catalyst 52 by detecting an oxygen concentration on the downstream side of the catalyst 52, and adjusts the rich injection amount on the basis of the determined deterioration degree and time length of the fuel cut.SELECTED DRAWING: Figure 1 |
