| 摘要 |
PURPOSE:To enable to detect air-fuel ratio as a function corresponding to 1:1, by detecting air-fuel ratio by the relative value of ionized currents by a plurality of flame rod sensors. CONSTITUTION:The characteristics of ionized-currents to air-fuel ratio can be changed with the position in flames where flame rod sensors are inserted. In the characteristics of ionized-current to air-fuel ratio detected by flame rod sensors 5a and 5b, the air-fuel ratio (P) in which the ionized currents Ifa and Ifb come to their peaks respectively are different from each other such as P=Pa and P=Pb, while the characteristics of output voltages V7a and V7b from current detecting circuits 7a and 7b are respectively proportional to the ionized currents Ifa and Ifb. The output voltages V7a and Vf7b from the current-detecting circuits 7a and 7b are fed into an air-fuel ratio detecting part 14. Both output voltage V1a and V1b from a logarithmic conversion circuit are proportional to the logarithmsof V7a and V7b, and the outut voltage Vout from a differential amplifying circuit is proportional to V1b-V1a. Accordingly, the characteristic of air-fuel ratio is a function corresponding to 1 to 1. |
