Ngk Spark Plug Company, Limited

Kunio Yanagi

Yoshiaki Kuroki

Hiroyuki Hayashi

Shinya Awano

Tomohiro Mabuchi

Takao Kojima

A sensor element including an insulative base (), a heating resistor (), an oxygen pump cell (), an oxygen detection cell (), and a diffusion-chamber-forming member () having a rate-controlling introduction portion () and defining a diffusion chamber () in cooperation with electrodes (), wherein these components have been subjected to simultaneous firing (i.e., cofiring) to form a unitary sensor element. A partition wall (), which extends from the diffusion-chamber-forming member and is made of alumina, is joined to a surface of a solid electrolyte () between two electrodes () of an Ip cell. Preferably, a region within 20 &#x3bc;m from the plane of junction joining the partition wall () to the solid electrolyte () contains no portion whose amount of non-alumina substances exceeds by 2% by mass (by weight) or more the amount of non-alumina substances of the diffusion-chamber-forming member ().

Gas sensor element having at least two cells

A multi-layer gas sensor element is described which comprises a solid electrolytic member, a substrate, and a porous member, wherein each of the substrate and the porous member has a thickness larger than that of the solid electrolytic member with respect to a lamination direction; the substrate and the porous member face each other and sandwich the solid electrolytic member; a ceramic component constituting the substrate in the highest volume percent is the same as the ceramic component constituting the porous member in the highest volume percent thereof; and the volume percent (R2) of the ceramic component contained in the porous member is 80% or more the volume percent (R1) of the ceramic component contained in the substrate.

Multi-layer gas sensor element and gas sensor comprising the same

A ceramic heater for heating a sensor such as an oxygen sensor has a ceramic substrate and a heater pattern formed on the substrate. A heater pattern 22 is tightly interposed between first and second alumina substrates 15 and 21. This heater pattern 22 has a meandering heating section 25 and a pair of leads 26 for connecting both ends of the heating section 25 to two terminals at the base side end. The heating section 25 is divided into a tip side subsection 25a located near the tip side end of the device, and a base side subsection 25b. Specifically, the wire width is made greater in the tip side subsection 25a than in the base side subsection 25b so that the resistance per unit length is lower in the tip side subsection 25a. The thus-designed heater section 25 produces a less amount of heat in the tip side subsection than in the base side subsection, and this distribution of heat generation can reduce the possibility of cracks and breakage of a wire.

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Aichi, Japan

Kunio Yanagi