| 摘要 |
PURPOSE:To enable proper air-fuel-ratio detection and also to detect nitrogen oxide concentration by providing an electrode which is made of platinum and rhodium alloy as the exhaust-side electrode of an oxygen sensor of a solid electrolyte. CONSTITUTION:The oxygen sensor is formed of a detecting element 23 of a zirconia solid electrolyte with a cavity part 22 where air is admitted and provided with a heater 21, an air-side platinum electrode 25, the exhaust-side platinum electrode 26, and the electrode 27 of platinum and rhodium alloy. Further, the electrode 27 which provides reducing operation decomposes nitrogen oxide in exhaust gas into nitrogen and oxide, the concentration of oxygen including a component which is used as nitrogen oxide is detected, and the detection result is processed to determine a proper air fuel ratio. Concentration which is detected through the electrode 26 is subtracted from the detected concentration to detect the concentration of nitrogen oxide from the concentration of oxygen used for nitrogen oxide production. |
