| 摘要 |
PURPOSE:To measure the density of O2 accurately and thereby perform control of the air-fuel ratio of a mixture gas supplied by providing a porous ceramic layer and a porous catalyst layer on the detection side in the leg part of a detecting element and by bringing the reaction on the surface of an electrode on the side of the detected gas to the state of chemical equilibrium in a short time. CONSTITUTION:The electrode 2 on the side of the detected gas of the leg part 1b projecting into the exhaust pipe of the O2 density detecting element 1 of the detector for the density of O2 in the exhaust gas is formed of film-shaped porous Pt or the like. On the surface of the electrode 2 the porous ceramic layer 4 is formed of MgO.Al2O3 or the like and then on the layer 4 is provided a part of the leg part 1b, composing 30-75% of the whole surface area thereof, in such a manner that it covers the element 1 from the closing end of the leg part toward the opening of the element 1. Next, on the layer 4 is formed the porous catalyst layer 5 prepared by making an alumina carrier bear Pt-Rh. Since the reaction of the constituents of the gas can be brought rapidly to the chemical equilibrium on the surface of the electrode 2 on the side of the detected gas by this constitution, the detection is performed accurately without the divergence of a characteristic curve of electromotive force from an expected position. |
