PURPOSE: To achieve a better response with a better low temperature operability by communicating one electrode formed on the surface of a solid electrolyte with an exhaust gas atmosphere through a groove and a porous member to minimize the space capacity of the electrode section while confining the flow of gas.
CONSTITUTION: Electrodes 13, 14 and 15, 16 are made of Pt or the like respectively on solid electrotytes 11 and 12 each made of stabilized ZrO2, a shallow groove 18 about 1μm thick is provided between the electrode 14 and 15 and then, the electrolytes 11 and 12 are laminated. 1V is applied surrounding a porous member 17 while a pump current Ip to the electrolyte 11 with the electrode 13 as cathode and the electrode 14 as anode. With such an arrangement, O2 in the exhaust gas passes through the electrolyte 11 as oxygen ion and then, returns to O2 with the electrode 14. Here, the groove regulates the amount of oxygen passing through the member 17 therefrom 18 to an extremely low level to check the current Ip thereby enabling a highly accurate detection even at a low temperature (about 300°C) in proportion to the concentration of O2 in the exhaust gas. An electromotive power es between the electrolyte 12 and the electrodes 15 and 16 is provided to compensate effect of temperature on the current Ip. When a heater is provided at the detector section to control the constant temperature the electrolyte 12 is eliminated and in stead, an alumina substrate or the like is provided.
MIKI MASAYUKI
SASAYAMA TAKAO
