NOx gas detecting apparatus

#1. Field of the Invention

#The present invention relates to a NOx gas detecting apparatus. More particularly, the present invention relates to a NOx gas detecting apparatus capable of detecting a nitrogen oxide gas (a NOx gas) contained in exhaust gas discharged from boilers, automobiles and the like, or in living environments with high sensitivity.

#2. Description of Related Art

#The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the objects, advantages and principles of the invention. In the drawings,

#FIG. 1 is a cross sectional view showing a NOx detecting apparatus consistent with the present invention;

#FIG. 2 is a view showing current-voltage characteristics with respect to an oxygen gas exhibited by oxygen pumping cells each having a Pt-Au electrode as a cathode;

#A detailed description of preferred embodiments of the present invention will now be given referring to the accompanying drawings. In FIG. 1, there is shown a cross section of a NOx gas detecting apparatus (hereinafter referred to as a “detecting apparatus”) consistent with a first preferred embodiment of the present invention. In FIG. 1, the detecting apparatus 10 is constructed of solid electrolytes 12a-12h, insulating layers 14a, 14b, 14c, each of which are disposed between the solid electrolytes 12d and 12e, between the solid electrolytes 12d and 12f, and between the solid electrolytes 12c and 12g, respectively, and an insulating layer 40a disposed at the undermost layer.

#Disposed inside the detecting apparatus 10 is a gas introducing chamber 16 and a gas discharging chamber 18. The gas introducing chamber 16 is a closed space provided with a gas introducing section 16a from which a measurement gas is introduced thereinto by gas diffusion. Inner walls of the gas introducing chamber 16 is constructed of the solid electrolytes 12b, 12c, 12f and 12d. Also, the gas discharging chamber 18 is a closed space provided with a gas discharging section 18a for discharging an oxygen gas which has been discharged thereinto through the solid electrolytes 12d and 12f. Inner walls of the gas discharging chamber 18 is constructed of the solid electrolytes 12d, 12e, 12f, 12g and 12h.

#In addition, the detecting apparatus 10 comprises an oxygen gas supplying cell 20, an oxygen pumping cell 24, an oxygen reference electrode generating cell 28, an oxygen monitoring cell 32, a NOx detecting cell 36, and a heater section 40.