| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To determine whether an NOx clean-up rate is lowered due to the degradation of an NOx selective reduction catalyst or due to the abnormality of urea water. <P>SOLUTION: When the NOx selective reduction catalyst 15 is degraded, the clean-up rate NR is increased according to the rise of a catalyst temperature TC as shown by a curve B1. When the supply amount or quality of the urea water is abnormal, the NOx clean-up rate NR is uniformly lowered as shown by a curve C. When the NOx clean-up rate NR comes within an area X<SB>2</SB>and also comes within an area Y<SB>1</SB>, the degradation of the catalyst occurs. When the clean-up rate comes within an area Y<SB>2</SB>, the supply amount or quality of the urea water is considered to be abnormal. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
