| 摘要 |
PURPOSE:To obtain an air-fuel ratio sensor which can detect rich-burn by a method wherein a measurement chamber is equipped with an oxygen control and supply means and a chemical equivalent point detection means and exhaust gas is introduced into this measurement chamber. CONSTITUTION:An oxygen control and supply means is composed of zirconia solid electrolytic plates 11a, 12a and a chemical equivalent point detection means is composed of zirconia solid electrolytic plates 11b, 12b. Measured gas (exhaust gas) is introduced into a space chamber (measurement chamber) B through a fine diffusion hole 14. The difference between the oxygen density in a reference air chamber A' and the oxygen concentration in the space chamber B is detected by the chemical equivalent point detection means. As an output voltage of an oxygen concentration cell which is the chemical equivalent point detection means changes step by step in the rich-side from a theoretical air-fuel ratio point, the theoretical air-fuel ratio point can be detected. Because the quantity of the oxygen introduced into the space chamber B can be optionally controlled by an oxygen pump which is the oxygen control and supply means, the air-fuel ratio can be shifted to the rich-side from the theoretical air-fuel ratio point and the optional air-fuel ratio can be detected. |
