| 摘要 |
PURPOSE:To correctly discriminate the activity of a sensor by supplying a prescribed voltage between electrodes of a battery element, stopping the supply, detecting the inter-electrode voltage of the element, determining the detected voltages as the 1st detected value and 2nd detected value and calculating the difference between the detected values. CONSTITUTION:The battery element 9 is constituted by providing an exhaust gas stagnating chamber to the inside of an oxygen ion conductive solid electrolyte member and an atm. gas chamber to the outside thereof, and attaching a pair of electrodes to the electrolyte member. The prescribed voltage VB is supplied via a resistor 11 to the battery element 9 and the inter-electrode voltage of the battery element 9 is read and is determined as the 1st detected value by a discriminating circuit 15. The supply of the voltage VB is then stopped and the inter-electrode voltage of the battery element 9 is read and is determined as the 2nd detected value by the circuit 15. The voltage difference DELTAV between the 1st detected value and the 2nd detected value is calculated and is compared with a reference voltage DELTAVr in the stage of a theoretical air-fuel ratio. The activity of an oxygen concn. sensor is discriminated to be normal when the voltage difference DELTAV < reference value DELTAVr is attained. The air-fuel ratio is detected from the current value of an oxygen pump element 8. The activity of the sensor is exactly discriminated in accordance with the 1st and 2nd detected values by which control of the air-fuel ratio from the starting stage of an engine is executed. |
