| 摘要 |
<p>PURPOSE: To detect deterioration according to the degree of an increase in emission so as to properly monitor a catalyst. CONSTITUTION: A ternary catalyst 13 is provided in the exhaust pipe 12 of an internal combustion engine 1, an A/F sensor 26 is arranged in its upstream side and a downstream side O2 sensor 27 is arranged in its downstream side. A CPU 3 in an ECU 31 executes air-fuel ration feedback control according to the detected result of the A/F sensor 26. The CPU 3 determined the activation of the ternary catalyst 3 when the inversion cycle of an air-fuel ration by the downstream side O2 sensor 27 exceeds a specified time and in this case, the amount of heat needed from an engine starting time to catalyst activation is estimated. This heat amount is calculated based on the integrated value of the amount of intake air (integrated intake air amount) from the engine starting to the catalyst activation. Then, the CPU 3 determines the deterioration of the ternary catalyst 3 according to the integrated value of the heat amount.</p> |
