| 摘要 |
<p>PROBLEM TO BE SOLVED: To highly accurately determine the deterioration state of an NOx catalyst by correcting one output value of any of upstream and downstream side temperature sensors according to a differential value at the time of starting an internal combustion engine in a detector for detecting the deterioration state of the catalyst based on a difference between an upstream and a downstream side temperatures of the exhaust catalyst. SOLUTION: Exhaust temperature sensors 10 and 11 are installed in the upstream and downstream sides of an NOx catalyst 9 provided in an exhaust pipe 8, an cooling water sensor 12 and an external temperature sensor 14 are provided, and the output signals thereof are inputted to an ECU 16. Then, a difference value between a upstream and downstream side exhaust temperatures of the exhaust pipe 8 at the time of starting the engine is calculated based on the detecting signals of the exhaust temperature sensors 10 and 11, and according to this difference value, the output value of any one of the temperature sensors 10 and 11 is corrected. That is, a map is collected for each temperature difference, the corrected value of the exhaust temperature sensor 11 is calculated for each temperature sensor 10 according to a value indicated by the exhaust temperature sensor 10 for each temperature difference, this corrected value is added to the value detected by the temperature sensor 11 and an obtained value is treated as a temperature after the correction of the temperature sensor 11.</p> |
