| 摘要 |
<p>PURPOSE:To make the discrimination of the deterioration of a catalizer possible in an air-fuel ratio control device for a V-type or a horizontal opposed type internal combustion engine whose cylinders are divided into plural partial cylinder groups, and especially to make the discrimination possible as for a catalytic converter rhodium in a double air-fuel ratio sensor system applied to an internal combustion engine whose cylinders are divided into plural banks. CONSTITUTION:In a double O2 sensor system in which many cylinders are divided into plural partial cylinder groups (A, B banks), and each partial cylinder group is provided with O2 sensors 13A, 13B on the upstream side, and an exhaust collecting part is provided with a O2 sensor 17 on the downstream side, and in addition to that, a catalytic converter rhodium is provided on a side above the O2 sensor 17 on the downstream side, when the deterioration of a catalizer is discriminated, the control period of the air-fuel ratio in each partial cylinder group is made identical for eliminating the disturbance caused by interference of an exhaust gas in the exhaust collecting part, and then relationship between the air-fuel ratios above and below the catalizer is examined.</p> |
