| 摘要 |
This device is a degradation judging device for an oxygen sensor having a reference electrode 23 and a measuring electrode 22 , both of which hold a solid electrolyte layer therebetween, and measuring oxygen concentrations based on an electromotive force that occurs in accordance with a difference between an oxygen partial pressure of the reference electrode 23 and an oxygen partial pressure of the measuring electrode 22 . A control unit 10 , which controls operations of intake and exhaust valves, a spark plug and a fuel injection valve, has a degradation judging means that detects an internal resistance value "R 1 " of the solid electrolyte layer 21 by applying a high-frequency alternating current between the reference electrode 23 and the measuring electrode 22 , and judges degradation of the solid electrolyte layer 21 by comparing an average value of the detected internal resistance value "R 1 " with a reference value. By this judgment, the degradation of the solid electrolyte layer 21 can accurately be judged, and an occurrence of the engine stall or emission failure can be prevented.
|
