| 摘要 |
PURPOSE:To easily and accurately detect the deterioration of the title detector by detecting the change quantity of an oxygen concn. detected value and comparing the same with a predetermined deterioration discriminating value to judge the deterioration of the detector. CONSTITUTION:An oxygen concn. detecting sensor 10 is formed by providing the introducing port 24 connected to an exhaust pipe to the gas diffusion chamber 22 formed to the substrate of an oxygen ion conductive solid electrolyte material 20 and exhaust gas is introduced through said port 24. An atmospheric reference chamber 26 is provided to one outside of the diffusion chamber 22 and electrode pairs 28a, 28b, and 30a, 30b are formed to the diffusion chamber to be allowed to respectively function as the electrolyte material 20, a pump element 32 and a battery element 34. The electromotive force of the element 34 corresponding to oxygen concn. is detected to be compared with reference voltage and the voltage corresponding thereto is applied to the element 32 to output a detected value on the basis of the pump current thereof. At this time, said current is changed in its direction corresponding to oxygen concn. and the oxygen concn. is controlled to predetermined concn. through the directional change of said current and the change of the current value is detected as the change of a voltage value through a detection resistor and subjected to linearization processing to detect a wide range of a concn. proportion value. |
