Gas sensor element, gas sensor, and production method thereof

Abstract

A gas sensor element includes an insulating ceramic base, a solid electrolyte body, and a heating element. The solid electrolyte body is disposed in an opening of the insulating ceramic base and has a measuring electrode affixed to one of major surfaces thereof and a reference electrode affixed to the other major surface. The measuring electrode is exposed to gas to be measured. The reference electrode is exposed to a reference gas. The heating element works to activate the solid electrolyte body and is mounted on one of opposed surfaces of the insulating ceramic base on the same side as the major surface of the solid electrolyte body on which the reference electrode is disposed. Specifically, the insulating ceramic base is located between the solid electrolyte body and the heating element, thereby ensuring a desired degree of electric insulation between the heating element and the reference electrode.

What is claimed is: 
     
         1 . A gas sensor element production method comprising:
 forming an insulating ceramic member which is planar and made of an electrically insulating ceramic material, the insulating ceramic member having opposed surfaces and a through hole;   forming a solid electrolyte body in the through hole of the insulating ceramic member, the solid electrolyte body being made of a ceramic material which conducts at least a given ion and having a first major surface and a second major surface;   forming a measuring electrode disposed on the first major surface of the solid electrolyte body to be exposed to the gas;   forming a reference electrode disposed on the second major surface of the solid electrolyte body to be exposed to a reference gas;   arranging a heating element disposed on one of the opposed surfaces of the insulating ceramic member on the same side as the second major surface of the solid electrolyte body, the heating element working to activate the solid electrolyte body;   preparing a hollow cylindrical ceramic member which is made of an electrically insulating ceramic material and has a closed end and an open end, the hollow cylindrical ceramic member also having a window formed in a peripheral surface thereof;   wrapping the insulating ceramic member around the hollow cylindrical ceramic member with the reference electrode facing the window of the hollow cylindrical ceramic member; and   firing the hollow cylindrical ceramic member around which the insulating ceramic member is wrapped.   
     
     
         2 . A gas sensor element production method as set forth in  claim 1 , wherein said forming steps of the insulating ceramic member and the solid electrolyte body prepare a stack of a planar solid electrolyte material and a planer insulating ceramic material and punch the stack to make the through hole in the insulating ceramic member and the solid electrolyte body cut from the planar solid electrolyte material to have a size substantially identical with that of the through hole and simultaneously to place the solid electrolyte body in the through hole.