| 摘要 |
PROBLEM TO BE SOLVED: To improve purifying capacity of a front-end catalyst without degrading purifying capacity of an NOx catalyst, in an exhaust emission control device for an internal combustion engine where the front-end catalyst having oxygen storing capacity is disposed upstream of the NOx catalyst. SOLUTION: The exhaust emission control device for an internal combustion engine disposes the front-end catalyst 46 having oxygen storing capacity upstream of the NOx catalyst 48, and executes air-fuel ratio reduction control to consume stored oxygen in the front-end catalyst 46 just before execution of rich spike control. During the execution of rich spike control, lean spike control for increasing an exhaust air-fuel ratio temporarily is executed. |
