| 摘要 |
PURPOSE:To detect oxygen with high accuracy by eliminating the diffusion irregularity of oxygen to a space part, by calibrating the current value of a pump corresponding to the concn. of oxygen in gas to be measured on the basis of the current value of a pump corresponding to the concn. of oxygen in the open air by a oxygen sensor. CONSTITUTION:A reference electrode 8 and a pump anode 9 are provided inside a solid electrolyte 7 and a pump cathode 10 is provided outside said electrolyte. A space part 15 is provided in an oxygen sensor and oxygen in reference gas is diffused and introduced into said space part 15 through a small orifice 5a. Electromotive force is generated by the difference between the oxygen partial pressure inside the solid electrolyte 7 and that of gas to be measured outside said electrolyte 7 but a pump current is flowed to electrodes 9, 10 so as to bring said electromotive force to a predetermined value and the current value thereof is detected to calculate the concn. of oxygen. Further, the pump current is flowed, in such a state that the oxygen partial pressure of the space part 15 is brought to that of the open air, to calibrate the pump current value corresponding to the concn. of oxygen in the gas to be measured on the basis of that to the concn. of oxygen in the open air. Therefore, the influence of diffusion factor of oxygen to the space part is removed and the concn. of oxygen in exhaust gas is detected with high accuracy and an air/fuel ratio can be made at optimum value. |
