Patent ID: 6770181
Filing Date: 2004-08-03
Classification: G01N

Abstract:
A nitrogen oxide sensor for measuring an amount of a nitrogen oxide component contained in a measurement gas existing in an external space, said nitrogen oxide sensor at least comprising:a substrate composed of an oxygen ion-conductive solid electrolyte to make contact with the external space; a first internal space formed at the inside of said substrate and communicating with the external space; a gas-introducing port for introducing measurement gas from the external space into said first internal space; a first diffusion rate-determining slit passage for introducing the measurement gas into said first internal space via said gas-introducing port under a predetermined diffusion resistance; a main pumping means including a first inner pumping electrode and a first outer pumping electrode formed at the inside and outside of said first internal space respectively, for pumping-processing oxygen contained in the measurement gas introduced from said external space, on the basis of a control voltage applied between said electrodes so that a partial pressure of oxygen in said first internal space is controlled to have a predetermined value at which NO is not substantially decomposable; a second internal space communicating with said first internal space; a second diffusion rate-determining slit passage for introducing an atmosphere pumping-processed in said first internal space into said second internal space under a predetermined diffusion resistance; and a measuring pumping means including a second inner pumping electrode and a second outer pumping electrode formed at the inside and outside of said second internal space respectively, for decomposing NO contained in said atmosphere introduced from said first internal space, by means of catalytic action and/or electrolysis to pumping-process oxygen produced by said decomposition, wherein: said amount of nitrogen oxide contained in the measurement gas is measured on the basis of a pumping current flowing through said measuring pumping means in accordance with said pumping-process effected by said measuring pumping means; each of said first and second slit passages has, when viewed in a plane substantially perpendicular to a longitudinal extension axis thereof, two dimensions, and at least one dimension is not more than 10 &mgr;m, and said at least one dimension is less than a smallest dimension of said first and second internal spaces.