| 摘要 |
PURPOSE:To easily detect the shift from a theoretical air/fuel ratio by simple and highly durable constitution by exposing a solid electrolyte substrate having an electrode and a gas diffusion limiting means mounted on the surface thereof to gas to be measured and detecting the internal resistance change of the substrate and comparing the detected value with the max. value of internal resistance showing a theoretical air/fuel ratio. CONSTITUTION:Porous electrodes 4, 6 composed of an yttria-zirconia solid solution and platinum, a platinum heater 8 and the porous gas rate limiting layer 12 for limiting gas diffusion covering the electrodes 4, 6 are provided to the single surface of a solid electrolyte substrate composed of a yttria- zirconia solid solution to form an air/fuel ratio sensor 1. When this sensor 1 is exposed to the exhaust gas of a vehicle passing through a catalyst, the internal resistance of the substrate 2 is changed corresponding to an air/fuel ratio and the corresponding output is taken out through the electrodes 4, 6 and compared with the output corresponding to the theoretical air/fuel ratio making internal resistance max. to detect the shift from the theoretical air/fuel ratio. By this method, the shift from the theoretical air/fuel ratio can be easily and certainly detected by simple and highly durable constitution. |
