| 摘要 |
PURPOSE:To improve a low-temperature responsiveness and to arbitrarily control an air excess rate, by a method wherein, in a detector for oxygen concentration in exhaust gas from an internal combustion engine, a solid electrolyte, which is charged with a DC current, is located adjoining an oxygen concentration cell which self-heats through application of an AC voltage. CONSTITUTION:A resistor 11, consisting of a plural number of minute particles having a negative resistance temperature factor, and a high resistance region layer, is of an oxygen ion conductive solid electrolyte. A resistor 10, togehter with a reference electrode 12 and a measured gas electrode 13, constitutes an oxygen concentration cell, the resistor 11 is firmly adhered to the electrode 13, and an electrode 14 is attached to the surface. A power source 15 with a frequency, in which polarization of an AC component consists of mainly polarization of the inside of the resistor 10, is connected between the electrodes 12 and 13. Additionally, a DC power source 18, supplying a DC current to the resistor 11, is joined to the electrodes 14, functioning as an anode, and the electrode 13. The resistor 11 is formed in a porous manner and the electrodes 12 and 14 are exposed to the air and gas to be measured, respectively. The surface oxygen concentration of the electrode 13 is controlled, and this permits the reliable detection of an oxygen concentration in exhaust gas with an air excess rate of other than 1.0. |
