| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve a problem in reducing NO stored in an NOx storage type reduction catalyst by a rich spike in the normal operation condition that a large quantity of fuel may be required. SOLUTION: When the quantity of NOx stored in the NOx storage type reduction catalyst, disposed in an exhaust passage of an internal combustion engine with a throttle valve in the air intake system and a spark plug above a cylinder, reaches at least a first prescribed value, the quantity of the stored NOx is reduced by the rich spike for enriching the air/fuel ratio temporarily. In this method of controlling the exhaust emission, the rich spike is carried out during the reduced speed fuel cut control operation with the throttle valve being closed when it is judged that the quantity of stored NOx is at least a second prescribed value smaller than the first prescribed value.</p> |
