Heated solid electrolyte oxygen sensor

Claim 1

In a galvanic exhaust gas sensor having a circular solid electrolyte member, a heater in subassembly with an outwardly flanged concentric tubular terminal for a reference electrode on said electrolyte member, an inwardly flanged concentric tubular metal shell surrounding said member and said heater-terminal subassembly, and means coacting with said terminal and shell flanges for holding said member, heater-terminal subassembly and shell together in a fixed predetermined concentric relationship, the improvement wherein said solid electrolyte member is a substantially flat circular disc having a reference electrode on one face, said heater includes a spiral resistance heating element having a substantially flat heating face, and said subassembly includes an elongated heating element terminal coaxially extending through said tubular electrode terminal, and electrical insulating means for supporting said heating element terminal on said electrode terminal in a fixed placement along the longitudial axis of said electrode terminal, each of said terminals having one end adjacent one end on the other terminal, said adjacent ends on said terminals respectively affixed to opposite ends of said heating element spiral with said flat heating face normal to said longitudinal axis, whereby coaxial assembly of said electrolyte disc, heater-terminal subassembly, and shell inherently aligns said disc and element faces and generally parallelly spaces them a fixed predetermined distance apart.