| 摘要 |
PURPOSE:To heighten the accuracy of detection over a wide range by detecting a current value and air-fuel ratio supplied to make an output of the oxygen partial pressure ratio detecting section of an oxgen sensor coincides with a target value, and judging abnormality of the sensor from the result and result of detection of voltage between two poles of a controlling section. CONSTITUTION:An atmosphere introducing section 15 is formed by laminating the first solid electrolyte 14 on an atmosphere introducing plate 13, and a gas introducing section 18 is formed by laminating the second solid electrolyte 17 on the electrolyte 14 through a spacer plate 16. An anode 20 and cathode 21 of a sensor cell, and a cathode 22 and anode 23 of a pump cell are provided on both faces of electrolytes 14, 17 opposite to each other. Current IP is supplied from a pump current supply circuit 37 of an air-fuel ratio detecting circuit 33 to make potential VS between sensor cells 20, 21 a target voltage Va, and air fuel ratio detection output V1 from the current IP and current VP between pump cells 23, 22 are outputted to an abnormality judging circuit 34 to detect the abnormality of the sensor 11 due to adhesion of carbon particles. At the same time, an output Vi is made monotonous and continuous over whole range of air fuel ratio. |
