| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a catalyst deterioration judgment device capable of accurately performing deterioration judgment of a catalyst without being influenced by operation conditions of the engine. <P>SOLUTION: The maximum value of hydrogen concentration in a downstream of the catalyst is detected (step 108) after starting supply of a reducing agent to the catalyst (step 104). It is judged whether the maximum value of hydrogen concentration is smaller than a predetermined value (step 112) after predetermined time T2 passes from start of supply of the reducing agent. If it is judged that the maximum value of hydrogen concentration is smaller than the predetermined value in the step 102, it is judged that the catalyst is deteriorated (step 114). On the other hand, if it is judged that the maximum value of hydrogen concentration is the predetermined value or higher, it is judged that the catalyst is normal (step 116). <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
