| 摘要 |
PROBLEM TO BE SOLVED: To obtain an air-fuel ratio detector by which an air-fuel ratio is detected precisely and with high accuracy by judging the air-fuel ratio to be a nonactive state and correcting error with reference to the air-fuel ratio in the output value of an air-fuel ratio sensor circuit on the basis of the output value of the air-fuel ratio sensor circuit when the temperature difference between a first cooling-water temperature at the stop of a previous operation and a second cooling-water temperature at the start of a present operation is at a prescribed temperature or higher. SOLUTION: An air-fuel ratio sensor 20 generates a current corresponding to an air-fuel ratio when a voltage is applied to an air-fuel ratio sensor circuit 30, the sensor circuit 30 generates an output which is proportional to the current, and the air-fuel ratio, of an internal- combustion engine 10, which corresponds to an output value stored in the sensor circuit 30 is read out by an air-fuel ratio detection means 40 on the basis of the map of the air-fuel ratio with reference to the output value. On the other hand, an active-state judgement means A judges the sensor 20 to be a nonactive state when the temperature difference between a first cooling-water temperature at the stop of the previous operation of the engine and a second cooling-water temperature at the start of its recent operation is at a prescribed temperature or higher, and an error with reference to the air-fuel ratio in the output value due to the individual difference of the sensor circuit 30 is corrected on the basis of the sensor circuit 30 by an error correction means B. |
