| 摘要 |
PURPOSE:To prompt the timing of starting the use of an oxygen sensor with an accurate and quick discrimination of active state, by feeding a discrimination voltage alone until active state is discriminated while the supply of a sensor driving voltage is stopped. CONSTITUTION:When power is supplied to a constant voltage circuit 5 and a control unit 9 with the starting of an engine, a discrimination voltage Vz is fed to an oxygen sensor 1 from a discrimination voltage supply means 6. The sensor output Es varies only with changes in the resistance value r3 of a thermistor 3, namely, the sensor temperature T alone thereby enabling accurate discrimination of active state without being affected by the concentration oxygen. When judging that the oxygen sensor 1 is active, a discrimination means 21 outputs a switching signal Sz to have a reference voltage supply means 22 supplying a sensor driving voltage V1 to the oxygen sensor 1 closing the contact of a relay 23. The sensor output Es is inputted into an oxygen concentration detecting means 24 and a rich/lean signal R/L is outputted into a control unit 9. |
