| 摘要 |
PURPOSE:To prevent a blackening phenomenon in inactive operation by supplying a fine current between electrodes made of oxygen pump elements, detecting the inner resistance value of the oxygen pump element and supplying a current detecting an oxygen concentration below a reference one to the oxygen pump element. CONSTITUTION:When the contents of Ip value command data is set so that a pump current value Ip can be the prescribed fine current value I1, the pump current of the fine current value I1 flows between electrode plates 5 and 6 made of the oxygen pump element 1. The output voltage of a differential amplifier circuit 18 is read as a pump voltage Vp between the electrode plates 5 and 6 made of the oxygen pump element 1, and the output voltage Vs of a noninversion amplifier 30 is read. The pump voltage Vp is divided by the fine current value I1 to take for a pump resistance value Rp, and the reference value R1 of the pump resistance value Rp is set in accordance with a voltage Vs'. Since the reference value R1 determined by the voltage Vs' is previously written in an air/fuel ratio control circuit 31, data on the corresponding reference value R1 is retrieved. If Rp>R1, the oxygen pump element 1 and a battery element 2 are inactive, and accordingly there is concern that the blackening phenomenon will occur. |
