| 摘要 |
<p>PURPOSE:To measure any variation in a detecting signal in a highly accurate manner by compensating the effect of response time to the detecting signal of an exhaust sensor downstream of a catalytic body on the basis of an exhaust side downstream temperature at the of this body, thereby judging a state of deterioration in the downstream side exhaust sensor. CONSTITUTION:In this air-fuel ratio controller of an internal combustion engine 2, both first and second exhaust sensors 28, 30 are installed in top and bottom of a catalytic case 26 set up in an exhaust pipe 22. On the basis of each detecting signal out of these sensors 28, 30, an air-fuel ratio is controlled for its feedback by a control means. In this case, an exhaust temperature at the downstream side of a catalytic body 24 is detected by an exhaust temperature sensor 32. In addition, on the basis of the detected exhaust temperature, both effects of response time to the detecting signal of the second exhaust sensor 30 due to a stored oxygen quantity of the catalytic body 24 and a temperature of this second exhaust sensor 30 itself are compensated respectively. Moreover, in response to the compensated value, a state of deterioration in the second exhaust sensor 30 is judged by a judging element 34a.</p> |
