| 摘要 |
PURPOSE:To detect an accurate air fuel ratio regardless of variance of characteristics among individual oxygen sensor bodies by setting the target voltage of the output voltage of a sensor part and the inflow current of a pump part to prescribed values. CONSTITUTION:An oxygen sensor 18 consists of a sensor part 16 and a pump part 17. A pump current Ip is supplied from a current supply means 23 to the pump part 17 of the oxygen sensor 18, and the current supply means 23 consists of a current control circuit 24 and a difference detecting circuit 25; and the pump current Ip of the pump part 17 is so set that the output voltage Vs of the sensor part 16 is switched to the target voltage Va which varies abruptly depending upon the air fuel ratio. When a fuel cut signal F/C is outptted from a control means 28, this target voltage Va is set by the air in an exhaust pipe properly according to the output Viair of a current value detecting means 27. Consequently, even when the oxygen sensor 18 has variance in individual difference, variance of Ip-A/F characteristics is eliminated. |
