| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect the poisoning (particularly, sulfur poisoning) of at least one of a plurality of storage/reduction NOx catalysts. <P>SOLUTION: In this deterioration diagnosing device for the plurality of storage/reduction NOx catalysts 16, 18 installed in series in an exhaust passage, the NOx storage capacity of each NOx catalyst is measured, and based on at least one of the ratio and the difference between these NOx storage capacities, the poisoning of at least the NOx catalyst 16 on the upstream side is detected. The degree of the poisoning is larger in the upstream side NOx catalyst 16 than in the downstream side NOx catalyst 18, and the ratio or the difference in NOx storage capacity between these catalysts when the catalysts are normally deteriorated is different from that when the catalysts are subject to a sulfur poisoning. By using the degree and the difference, the poisoning of at least the former is detected separately from the normal deterioration. <P>COPYRIGHT: (C)2009,JPO&INPIT |
