Ngk Spark Plug Company, Limited

Yasumitsu Shimizu

Seiji Oya

Takayuki Kito

Disclosed is a stacked-type plate-shaped sensor element for detecting the concentration of a specific gas component in a gas under measurement. The sensor element includes: a first ceramic layer; a pair of measurement and reference electrodes stacked on a front end part of the first ceramic layer; a through hole formed through at least the first ceramic layer in a rear end side of the sensor element; a through hole conductor disposed on an inner wall of the through hole; a porous reference lead extending between the reference electrode and the through hole conductor; a gas-impermeable second ceramic layer arranged on the first ceramic layer to cover at least the reference lead; and a ventilation portion provided, in the form of a hollow space or a porous substance, between the first and second ceramic layers at a position facing the through hole and communicating with the reference lead.

Gas sensor

A gas sensor element of an air/fuel ratio sensor has a structure in which at least a part of an end portion of a porous electrode is sandwiched between a porous member and a solid electrolyte member. Therefore, it is possible to restrain shrinkage of the porous electrode during manufacture of the gas sensor element, which shrinkage would otherwise occur at the time of heating in a debindering step or at the beginning of a firing step, whereby occurrence of green breakage in the solid electrolyte member is restrained. Thus, cracking due to green breakage is restrained from occurring in the solid electrolyte member produced through firing. Since the end portion of the porous electrode can receive oxygen through the porous member, blackening of the solid electrolyte member can be prevented.

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Kiyosu, Japan

Yasumitsu Shimizu