| 摘要 |
<p>PROBLEM TO BE SOLVED: To aim at improvement in purification rate of NOX contained in exhaust gas when NOX absorbent is applied to an engine in which an engine air/fuel ratio is controlled within a narrow air/fuel ratio range centering round a theoretical air/fuel ratio. SOLUTION: An O2 sensor 25, an NOX absorbent 18 and an O2 sensor 20 are arranged in this sequence from upper stream side in the exhaust gas passage 17 of an engine 1 and also the fuel injection quantity of the engine 1 is controlled on the basis of the output of the O2 sensor 20. ECU 30 slowly increases a fuel injection quantity when an exhaust gas air/fuel ratio detected by the O2 sensor 20 is lean and slowly decreases it when it is rich and also when the output of the O2 sensor 20 is changed from rich to lean, the fuel injection quantity is increased in a step state for a specific period.</p> |
