| 摘要 |
PURPOSE:To enable control of an air-fuel ratio to a target air-fuel ratio by discriminating whether the air-fuel ratio is larger or smaller than the target air-fuel ratio by the output from the 1st oxygen sensor and discriminating the deviation thereof from the target air-fuel ratio according to the flush current value to the 2nd oxygen sensor. CONSTITUTION:Whether an air-fuel ratio is larger or smaller than a target air- fuel is discriminating by the output Vs1 of the 1st oxygen sensor 20. Whether said ratio is to be corrected for an increase or for a decrease is determined according to the result of the discrimination. On the other hand, the magnitude of the deviation of the air-fuel ratio from the target air-fuel ratio is judged by detecting the magnitude of the flush current I2 to the 2nd oxygen sensor 21. The fuel can be therefore gradually increased or decreased when the deviation of the air-fuel ratio from the target air-fuel ratio is small and the air-fuel ratio can be controlled always to the target air-fuel ratio without deviating the air-fuel ratio more than necessarily from the target air-fuel ratio. If the air-fuel deviates considerably from the target air-fuel ratio on account of fuel cut, etc., the fuel can be quickly increased or decreased, by which the air-fuel ratio is controlled quickly to the target air-fuel ratio. |
