| 摘要 |
PURPOSE:To detect exactly the entire region of an air-fuel ratio and theoretical air-fuel ratio by disposing an oxygen pump and an oxygen sensor to face each other apart at a slight space and changing over suitably the electrode polarities thereof. CONSTITUTION:A solid electrolyte oxygen pump 6 and a solid electrolyte oxygen sensor 10 are disposed to face each other at a slight space (d) of about 0.1mm. in an exhaust pipe 1. The electromotive force (e) generated between the electrodes 8, 9 of the sensor 10 is impressed via a polarity change-over switch SW and a resistor R1 to the inversion input terminal of an effect amplifier A and a transistor TR is driven by the output proportional to a difference from the reference voltage VRef impressed to the non-inversion input terminal, by which the pump current IP flowing between the electrodes 4 and 5 of the pump 6 is controlled. The electromotive force of the sensor 10 is controlled to about 200mV by the above-mentioned constitution, by which the change in the pump current IP of the pump 6 is detected and the exact detection of the theoretical air-fuel ratio and the entire region of the air-fuel ratio is made possible. |
