Ngk Spark Plug Company, Limited

Other

Niterra Co., Ltd.

Hiroshi Isomura

Takayoshi Atsumi

Shoji Akatsuka

Akio Mizutani

Koji Shiono

Osamu Shinkai

Masamine Takagi

Takao Kojima

Hisaharu Nishio

Takaya Yoshikawa

Nobuhiro Hayakawa

Seiichi Hosogai

Keita Nakagawa

Hiroshi Kubota

Hiroyuki Fujita

Junji Kawai

Teppei Okawa

Toru Furuichi

Katsuyoshi Hidaka

Midori Matsumura

Kazuki Yoshioka

Ryosuke Ota

Aya Sato

Yukichika Ito

Kazuma Ito

Takanori Ishikawa

A gas sensor element includes a solid electrolyte body, a first electrode, a second electrode, and a protective layer. The protective layer includes at least a first catalyst layer that supports a first catalyst metal other than a metal facilitating a reduction reaction of nitrogen oxide and a second catalyst layer that supports only a second catalyst metal facilitating the reduction reaction of the nitrogen oxide. The first catalyst layer and the second catalyst layer are arranged in a path through which a gas under measurement is supplied from the outside of the gas sensor element to the first electrode in such a manner that the first catalyst layer and the second catalyst layer are not in direct contact with each other.

Gas sensor element and gas sensor

Disclosed is a gas sensor element having: a solid electrolyte body containing oxygen-ion conductive ZrO; a detection electrode disposed on the solid electrolyte body to be exposed to a gas under measurement; and a reference electrode disposed on the solid electrolyte body to be exposed to a reference gas. In the gas sensor element, the detection electrode contains Pt and ZrO; the detection electrode has a thickness of 3 to 10 &#x3bc;m; the amount of ZrOcontained relative to Pt in the detection electrode is 12 to 18 wt %; the detection electrode has a porosity of 5% or lower; and, in a particle size distribution graph of ZrOparticles in the detection electrode, a cumulative value of peaks appearing in a range of 0.025 &#x3bc;m to 0.200 &#x3bc;m is 60 to 75%, and a cumulative value of peaks appearing in a range of 1.000 &#x3bc;m to 3.162 &#x3bc;m is 2 to 7%.

A gas sensor according to the present invention includes a sensor element made of a solid electrolyte and having at least a cylindrical portion arranged coaxially with an axis of the sensor element and a front end portion closing a front end of the cylindrical portion and a heater formed into either a cylindrical shape or a cylindrical column shape and located inside the sensor element to heat the sensor element by heat generation thereof, wherein a front end portion of the heater is in contact with an inner surface of the front end portion of the sensor element; and wherein a lateral portion of the heater is in contact with an inner circumferential surface of the cylindrical portion of the sensor element.

Gas sensor

A gas sensor including a detection element (), wherein a detection electrode (D) and a reference electrode (B) are provided on an outer circumferential surface (A) and an inner circumferential surface, respectively, of a closed-bottomed tubular solid electrolyte body (). A heater inserted into the tubular hole of the detection element () is in contact with the reference electrode at point Q. The detection electrode (D) is partially formed in the vicinity of a position which faces the point Q with the solid electrolyte body () intervening therebetween, and the surface area of the detection electrode (D) is 8% to 20% of the surface area of a detection portion ().

A gas sensor includes an inner electrode formed on an inner surface of a base body. The inner electrode has an inner sensing portion formed in a gas contact inner region such that the inner sensing portion is located on the whole of a heat-facing area of the gas contact inner region facing a heating portion in a radial direction of the base body, a terminal contact portion formed in a rear end region such that the terminal contact portion is located in at least a part of the rear end region in a circumferential direction of the base body and a lead portion formed only on a part of the inner surface of the base body in the circumferential direction of the base body so as to connect the inner sensing portion and the terminal contact portion to each other.

A gas sensor comprising: the gas sensor element defined; the cylindrical metal shell defined herein; and the protector defined herein, wherein the protector defined herein has a double structure including the cylindrical inner cover portion and the outer cover portion both defined herein, and a leading end portion positioned on a leading end side of the support face of the metal shell, the outer cylindrical portion and the inner cylindrical portion are arranged to construct an inner gas introducing passage for guiding the object gas introduced from the outer gas introducing apertures, between the outer cylindrical portion and the inner cylindrical portion, across a trailing end of the inner cylindrical portion closer to a leading end side, as viewed in an axial direction, than an inner circumferential side end edge of a joining face joining an inner circumference and an outer circumference of a leading end portion of said metal shell, into a clearance between the inner cover portion and the leading end portion of the gas sensor element.

A sensor of the present invention includes a sensor element; a metallic shell; an outer tube member fixed to a rear end portion of the metallic shell; and a protective outer tube member covering an outer surface of the outer tube member. The outer tube member has a seal portion being circumferentially in contact with the protective outer tube member directly or via another member, and a front-side separation portion located frontward of the seal portion and spaced apart from and facing the protective outer tube member. A metal coating layer (plating layer) is formed on the outer surface of at least the front-side separation portion of the outer tube member.

Sensor

A gas sensor having a gas sensor element which includes: a reference electrode; a solid electrolyte layer having oxygen ion conductivity; a detection electrode; and an electrode-protecting layer covering the detection electrode. The electrode-protecting layer is a porous body carrying catalytic metal, and includes: a detection electrode side portion having a catalytic metal loading ratio of more than 0% by weight and not more than 0.005% by weight; and a surface side portion provided closer to the outer surface of the electrode-protecting layer than the detection electrode side portion, the surface side portion having a catalytic metal loading ratio of 0.01% by weight or more.

Gas sensor and method for manufacturing the same

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

A gas sensor comprising: a gas sensor element extending in an axial direction; a cylindrical metal shell enclosing said gas sensor element such that a leading end portion of said gas sensor element protrudes from its own leading end; and a protector fixed on said metal shell and covering said leading end portion of said gas sensor element, wherein said protector includes: a cylindrical outer cover portion fixed on said metal shell and having gas introducing apertures; and a cylindrical inner cover portion arranged on an inner side of said outer cover portion and having elastic portions being capable of being elastically deformed by a pushing force acting in an axial direction, and said inner cover portion is so clamped between said metal shell and said outer cover portion that said elastic portions are elastically deformed by said axial pushing force.

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

There is disclosed an oxygen sensor disposed before an exhaust gas purifying catalyst of an engine which uses a hydrocarbon containing fuel with a H/C ratio of three or more. An oxygen sensor,is provided with a solid electrolytic body,which can generate a difference in oxygen concentration with reference gas and measured gas, a reference electrode,and a detection electrode,formed on inner and outer surfaces of the solid electrolytic body,, and a porous protective layer,for covering the detection electrode,. The detection electrode,is formed only of a metal like Pt which promotes oxidizing reaction of methane to have a thickness of 1 to 2 &mgr;m. In the protective layer,, only a second protective layer,carries Pt catalyst,which promotes oxidizing reaction of hydrogen, and the amount of carried catalyst is in the range of 0.5 to 7 mol % relative to the whole of the second protective layer,. According to the oxygen sensor,, even if a large amount of hydrogen is exhausted, for example, from CNG engine, or even if a large amount of methane is exhausted, an excellent engine control can be realized.

Oxygen sensor

Disclosed is a process for the formation of an electrode for sensor element which comprises the formation of a platinum electrode on a solid electrolyte formed in a predetermined shape as a sensor element by electroless plating, wherein said electroless plating is effected in a platinum (II) complex solution as a plating solution on which a reducing agent for reducing said platinum (II) complex is acted.

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Nagoya, Japan

Hiroshi Isomura