| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a catalyst deterioration diagnosis device capable of accurately diagnosing the deterioration of a storage reduction type NOx catalyst arranged in an exhaust gas passage of an internal combustion engine. <P>SOLUTION: The device diagnoses deterioration of the storage reduction type NOx catalyst 18 arranged in the exhaust gas passage 12 of the internal combustion engine 10, and includes a NOx sensor 25 arranged in a downstream side of the NOx catalyst 18. NOx sensor output integration value is calculated by integrating output of the NOx sensor 25 during a period including a time near completion of rich spike. Deterioration of the NOx catalyst 18 is diagnosed based on the NOx sensor output integration value. The NOx sensor 25 also has a function detecting NH<SB>3</SB>, and is, in an embodiment, a limit current type NOx sensor. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
