AIR-FUEL RATIO SENSOR WITH HEATER

摘要

PURPOSE:To eliminate the influence generated by the rate determination of gas diffusion on the detection of an air-fuel ratio and to widen the detection range of the air-fuel ratio by constituting the inside surface of a zirconia solid electrolyte to a tapered shape so that a spacing with a heater is sufficiently provided. CONSTITUTION:A platinum electrode 2 to come into contact with an exhaust gas is provided on the inside surface of the solid electrolyte having a bag tubular shape and a platinum electrode 3 to come into contact with the atmospheric air is provided on the outside surface. The bar-shaped heater 5 consisting of ceramics is inserted into the electrolyte 1. The inside surface of the electrolyte 1 is tapered from the aperture near to the electrode 3 so that the sufficient spacing from the heater 5 is obtd.; in addition, a parallel part to diminish the spacing with the heater 5 is provided on the part of the electrode 3 so that the temp. stability of the detecting part is obtd. The rate determination of the gas diffusion in this spacing is prevented by increasing the spacing between the solid electrolyte 1 and the heater 1 in such a manner, by which the sufficient amt. of oxygen can be supplied from the atm. side into the bag tube and the detection range of the air-fuel ratio particularly in a rich region is widened.