| 摘要 |
PURPOSE:To reduce the exhaust emission by installing the air-fuel ratio sensors an the upstream and downstream sides of a catalyst and varying the comparison voltage of the second sensor on the downstream side according to the load and calculating the air-fuel ratio control quantity set according to the load, according to the result of the second comparison. CONSTITUTION:Air-fuel ratio sensors 13 and 15 are installed on the upstream and downstream sides of a catalytic converter 12 in an exhaust pipe 11. A controller 10 detects the engine load by receiving the signal of an air flow meter 3, and varies the comparison voltage of the second air-fuel ratio sensor 15 according to the load. Further, each air-fuel ratio control quantity which is provided according to the load is calculated according to the result of the comparison by the second comparator. The air-fuel ratio is controlled according to the result of the comparison by the first air-fuel ratio sensor and the air-fuel ratio control quantity corresponding to the load. Thus, the exhaust emission can be reduced.
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