| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent deterioration of the exhaust performance in a diesel engine. <P>SOLUTION: A rich spike controlling means for desorbing the NOx deposited on an NOx trap catalyst 12 by reducing the excess air ratio of the exhaust gas starts a rich spike control when the deposition amount NOx0 of the NOx deposited on the NOx trap catalyst 12 is same as or more than a rich spike execution judging threshold value NOx1. The rich spike execution judging threshold value NOx1 is calculated by correcting a preset base execution judging threshold value NOx1base using at least one of the temperature of the NOx trap catalyst 12 and the exhaust gas flow rate. Thereby, since the temperature of the NOx trap catalyst 12 and the exhaust gas flow rate, which affect the purification ability of the NOx trap catalyst 12, are taken into consideration, deterioration of the exhaust performance due to execution of the rich spike control is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT |
