| 摘要 |
PURPOSE:To reduce deterioration in the lapse of time in characteristics and perform air fuel ratio detection without any influence of temperature variation of an atmosphere to be measured by communicating one of a couple of oxygen sensors with the atmosphere to be measured and bringing the other into contact with an atmosphere whose oxygen concentration is controlled, and detecting an air fuel ratio from the potential at the intermediate point between both sensors. CONSTITUTION:Oxygen sensors 26 and 36 consisting of transition metal oxides 23 and 33, and electrodes 24 and 25, and 34 and 35 are provided on both surfaces of a plate type electric insulator 22. A pump current Ip is flowed from a pump current source 63 to the oxygen pump 46 consisting of an oxygen ion conductive electrolyte 43 and a couple of electrodes 44 and 45 to control the oxygen concentration of a control atmosphere space 43. The small hole 46 of the oxygen pump 46 contacts the atmosphere to be measured together with the oxygen sensor 36. Both sensors 26 and 36 are connected to a power source 61 in series and the voltage Vs at the intermediate point is measured by a voltage measuring instrument 62. The resistance of the sensor decreases when Ip is flowed, so Ip when Vs is constant is measured to detect the air fuel ratio. Deterioration in the lapse of time in characteristics which is caused by clogging, etc., is reduced because of multilayer structure. |
