| 摘要 |
PURPOSE:To enhance the durability and detection accuracy of a sensor, by cyclically changing over objective voltage to positive and negative predetermined values and calculating the same on the basis of at least one of a pump current value when the objective voltage is a positive predetermined value and that when a negative predetermined value. CONSTITUTION:The sensor part 14 of an oxygen sensor 1 has a measuring electrode and a reference electrode arranged thereto and outputs voltage Vs corresponding to the oxygen partial pressure ratio between both electrodes. A pump electrode is arranged to a pump part 15 and the oxygen partial pressure ratio between both electrodes of the sensor part is determined corresponding to the value of an influent current Ip. A current supply means 31 supplies the current Ip to the pump part 15 so as to bring voltage Vs to predetermined objective voltage Va and an objective voltage change- over means 32 cyclically changes over voltage Va to positive and negative predetermined values. An oxygen concn. detection means 37 detects the current Ip and outputs a voltage signal Vi corresponding to oxygen concn. from the value of the current Ip when voltage Va is a positive predetermined value and that when a negative predetermined value. By this method, the durability and detection accuracy of the sensor can be enhanced. |
