| 摘要 |
<P>PROBLEM TO BE SOLVED: To properly control exhaust emission by improving the accuracy for determining the purification performance of a catalyst. <P>SOLUTION: In this engine system, the NOx storage/reduction type catalyst 21 is installed in the exhaust pipe 18 of an engine 10, and a fuel adding valve 25 is installed on the upstream side of the catalyst. An ECU 30 performs NOx reduction control for supplying an NOx reduction component to the catalyst 21 for reducing and removing the NOx stored in the NOx catalyst 21 and determines the purification performance of the NOx catalyst 21 based on the supplied amount of the reduction component required for the reduction and removal of the NOx when the NOx reduction control is performed or the parameters relating to the supplied amount. In particular, the ECU 30 determines whether the unburned fuel supplied to the NOx catalyst 21 is excessive or not when the NOx reduction control is performed. When the ECU 30 determines that the unburned fuel is excessive, it prohibits the determination of the purification performance of the NOx catalyst 21. <P>COPYRIGHT: (C)2007,JPO&INPIT |
