Ngk Spark Plug Company, Limited

Koji Shiono

Takayoshi Atsumi

Hiroshi Isomura

Masamine Takagi

Kentaro Mori

Naoki Yamada

Takanori Ishikawa

Kunio Imai

A gas sensor element () includes: a solid electrolyte body () having a bottomed tubular shape and a closed front end, and extending in the direction of an axial line O; an inside electrode () which is provided on an inner surface of the solid electrolyte body; an outside electrode () which is provided on an outer surface of the solid electrolyte body; and a porous protective layer () which covers the outside electrode, the porous protective layer has an inside region () which covers the outside electrode and an outside region () which covers the inside region and has a lower porosity than the inside region, and the outside region is formed of a sintered body of ceramic and glass.

Gas sensor element and gas sensor

A gas sensor comprising: a gas detecting element extending in an axial direction and including a detecting electrode provided on an outer surface of a leading end side of the gas detecting element, and a lead portion connecting to the detecting electrode and extending toward a rear end side of the gas detecting element; a cylindrical metal shell housing the gas detecting element such that the gas detecting element protrudes from a leading end side of the metal shell; a powder layer filling a gap between the gas detecting element and the metal shell and covering at least a portion of the lead portion; and an insulating layer provided between the powder layer and the lead portion. Also disclosed is a method for manufacturing the gas sensor which includes forming the insulating layer by at least: applying a glass paste; drying the glass paste; and heat-treating the glass paste.

Gas sensor, and gas sensor manufacturing method

To provide a gas sensor element having a base body whose durability is unlikely to deteriorate during the use and exhibiting excellent endurance and responsiveness. [Means for Solution] A gas sensor elementcomprising: a closed-bottomed cylindrical base bodymade of solid electrolyte which contains zirconia as a principal component; an outer electrodeformed on an outer surface of the base body; an inner electrodeformed on an inner surface of the base body; and an adhesive layerformed between the base bodyand the outer electrodeand containing zirconia as a principal component, wherein a proportion of tetragonal in zirconia particles of the base bodyfalls within the range from 45% or more to 60% or less and, wherein a proportion of tetragonal in zirconia particles of the adhesive layeris greater than that of tetragonal in zirconia particles of the base body

The oxygen sensor of the present invention has excellent durability capable of effectively preventing contamination with lead or the like for a detection electrode even in low temperature exhaust gases, and having stable response over a long period of time. The contamination preventive layer provided in the sensor device comprises composite powders having coarse powders covered therearound with fine powders, and hollows not filled with fine powders are scattered in gaps among the composite powders. Both the coarse and fine powders comprise ceramic powders. Further, it is particularly preferred that the ceramic powders are powders of a titania powder having a peak at 1 &#x3bc;m or less and a composite ceramic powder containing alumina such as spinel having a peak at 10 &#x3bc;m or more. The contamination preventive layer can be formed by coating a slurry containing ceramic powders of different specific surface areas, an organic binder and a solvent such as methanol on the surface of the electrode protection layer followed by drying.

Oxygen sensor and a manufacturing method of the sensor device

The oxygen sensor of the present invention has excellent durability capable of effectively preventing contamination with lead or the like for a detection electrode even in low temperature exhaust gases, and having stable response over a long period of time. The contamination preventive layer provided in the sensor device comprises composite powders having coarse powders covered therearound with fine powders, and hollows not filled with fine powders are scattered in gaps among the composite powders. Both the coarse and fine powders comprise ceramic powders. Further, it is particularly preferred that the ceramic powders are powders of a titania powder having a peak at 1 &mgr;m or less and a composite ceramic powder containing alumina such as spinel having a peak at 10 &mgr;m or more. The contamination preventive layer can be formed by coating a slurry containing ceramic powders of different specific surface areas, an organic binder and a solvent such as methanol on the surface of the electrode protection layer followed by drying.

Oxygen sensor and manufacturing method of sensor element

A gas sensor element includes a solid electrolyte layer having a plurality of projections formed on its outer surface, an inner electrode formed on the inner surface of the solid electrolyte layer, an outer electrode formed on the outer surface of the solid electrolyte layer, an outer electrode formed on the outer surface of the solid electrolyte layer and a spinel protection layer formed on the outer electrode for protection. The projections are formed on the outer surface of the solid electrolyte layer such that they are formed in a single layer; an area occupied by the projections accounts for 10% to 85% of the outer surface of the solid electrolyte layer and the distance between the neighboring projections is 5 &mgr;m to 300 &mgr;m. Thus, the outer electrode is formed on the solid electrolyte layer in such a manner as to penetrate into pits formed between neighboring projections and is thus strongly bonded to the solid electrolyte layer, thereby improving thermal durability. Also, since pores are hardly formed or are not formed at all between projections, a strong bond is established among the solid electrolyte layer, the outer electrode, and the protection layer, thereby improving durability against high temperature and high humidity.

Growing community of inventors

Komaki, Japan

Koji Shiono