Patent ID: 6319377
Filing Date: 2001-11-20
Classification: G01N,Y02A

Abstract:
A nitrogen oxide sensor comprising:a gas chamber communicating with an environment to be detected,an oxygen pumping portion mounted on a solid electrolyte body forming a wall of said chamber for sucking or discharging an oxygen gas electrochemically and including an oxygen pumping electrode in said gas chamber, said oxygen pumping electrode also serving as an NOx converting electrode and comprising an alloy of Pt and 1 to 20 wt. % of Rh;a NOx gas detecting portion for detecting NOx including a detecting electrode and a counter electrode mounted on a solid electrolyte body separate from that on which said oxygen pumping portion is mounted and either the detecting electrode or the detecting electrode and the counter electrode of said NOx gas detecting portion being arranged in said gas chamber so that at least said detecting electrode faces said oxygen pumping electrode serving as an NOx converting electrode,a gas inlet port for introducing a gas to be measured from said environment into said gas chamber and having a diffusion resistance such that NOx is converted in said gas chamber at a voltage of of 1.5 V or lower applied to said oxygen pumping electrode serving as an NOx converting electrode;a heating mechanism for keeping said oxygen pumping portion and said NOx gas detecting portion within a predetermined temperature range, andmeans for measuring the NOx concentration on a basis of an electromotive force generated between said detecting electrode and said counter electrode.