Nippondenso Co., Ltd.

Denso Corporation

Other

Nippon Soken, Inc.

Toshitaka Saito

Hiromi Sano

Masatoshi Suzuki

Naoto Miwa

Akio Tanaka

Keigo Mizutani

Satoru Nomura

Tomio Sugiyama

Kiyomi Kobayashi

Masaya Fujimoto

Masami Ouki

Katsuhiko Tanaka

Namitsugu Fujii

Daisuke Makino

Yasumichi Hotta

Kazunori Suzuki

Toru Katafuchi

Mitihiro Yamakawa

Akira Miyashita

Tadashi Inaba

Hideaki Takahashi

Masahiro Shibata

Jiro Sakata

Syuichi Nakano

Tadashi Nakamura

Keiichi Saji

Hiroo Imamura

Yumi Masuoka

Hiroshi Furuhashi

Katsuhiro Ishikawa

Syohei Udo

Syozo Tanida

Makato Nakae

Soji Ota

A gas sensor includes a measurement gas chamber into which a measurement gas is introduced. An oxygen pumping cell adjusts an oxygen concentration in the measurement gas chamber. An oxygen monitor cell has a monitor electrode exposed in the measurement gas chamber. The monitor electrode has an oxidizing activity with respect to a specific component of the measurement gas. A sensor cell has a sensor electrode exposed in the measurement gas chamber. The sensor electrode has an oxidizing activity with respect to the specific component of the measurement gas which is lower than the oxidizing activity of the monitor electrode. An oxygen-ion current in the oxygen monitor cell is detected. An oxygen-ion current in the sensor cell is detected. A concentration of the specific component of the measurement gas is detected from a relation between the detected oxygen-ion currents in the oxygen monitor cell and the sensor cell.

Gas sensor and method of detecting gas concentration

The oxygen concentration detector of the present invention includes a sensor element having a solid electrolyte and having an external electrode and an internal electrode provided on the external surface and the internal surface, respectively, and a heater provided adjacent to the internal surface of the sensor element, in which a high-emissivity layer consisting of a material having a high emissivity is provided on the internal surface of the sensor element and/or the surface of the heater.

Oxygen concentration detector

In order to raise accuracy of measurement, a compound layered type of sensing device is provided. The device comprises a plurality of solid electrolyte plates and first to third electrochemical cells. Each cell has a single pair of electrodes disposed on the solid electrolyte plates. A concentration of a gas specified from a gas to be measured pre-processed based on oxygen pumping by the first electrochemical cell is detected by the second electrochemical cell. A difference in electromotive force between the gas to be measured and a reference gas is detected by the third electrochemical cell. The single pair of electrodes of the third electrochemical cell is disposed on the same surface of one of the solid electrolyte plates, and both of the first and third electrochemical cells are located with different ones of the solid electrolyte plates.

Compound layered type of sensing device for multiple measurement

A NO gas detecting apparatus including an oxygen pumping cell for removing oxygen from a measurement gas, and a NO detecting cell positioned downstream from the oxygen pumping cell to detect concentration of NO in the measurement gas, the NO detecting cell being configured to measure current which flows when oxygen generated from reducing NO is pumped, wherein the NO detecting cell has a NO detecting cathode made of an electrode material including at least one alloy selected from the group consisting of a Pt-Pd alloy, a Pt-Au-Pd alloy, and a Pt-Pd-Rh alloy.

NOx gas detecting apparatus

An objective gas to be measured is introduced into first and second chambers which are connected via a diffusion resistive passage. A first electrochemical cell is provided in the first chamber for pumping in and out oxygen in accordance with an applied voltage. A second electrochemical cell is provided in the second chamber and responsive to application of a predetermined voltage for generating a sensor current representing a specific gas concentration in the objective gas. The first electrochemical cell is located between the first chamber and a reference gas chamber so that oxygen pumping in and out operation can be performed between the first chamber and the reference gas chamber.

Multilayered gas sensing element employable in an exhaust system of an internal combustion engine

An exhaust gas side electrode is provided on one surface of a solid electrolytic substrate. A reference gas side electrode is provided on an opposite surface of the solid electrolytic substrate so as to be exposed to a reference gas stored in a reference gas chamber. Each lead of the electrode is connected to a signal output terminal. This sensor satisfies a relationship B/A<0.5, wherein 'A' represents an overall resistance value of an electric path including the solid electrolytic substrate, the electrodes, and their leads in a sensor activated condition, while 'B' represents a resistance value of the leads at a room temperature. Some embodiments may be arranged such that at least one of the leads has a low resistance portion located in the vicinity of the electrodes and a high resistance portion located in the vicinity of signal output terminals. For example, at least one lead may have a smaller resistance per unit length near the electrodes as compared to the resistance per unit length at a location far from the electrodes.

Multilayered gas sensor and a related gas concentration detecting system

An objective gas is successively introduced into first and second chambers which are connected via a narrow passage. A first monitor cell, provided on a surface of the first chamber, generates an electromotive force representing an oxygen concentration in the first chamber. A second monitor cell, provided on a surface of the second chamber, generates an electromotive force representing an oxygen concentration in the second chamber. A voltage applied to a pump cell is controlled based on the electromotive forces obtained from the first and second monitor cells.

Gas sensing element employable in an exhaust system of an internal combustion engine

An oxygen sensor element includes a solid electrolyte having cavities on a surface thereof and an electrode formed on the surface of the solid electrolyte. In a method of producing the oxygen sensor element, a solution containing a noble metal compound for nucleus formation is first applied to an electrode forming portion of the solid electrolyte to form a coating film. Then, the coating film is heat-treated to form a nucleus forming portion where noble metal nuclei are deposited. Subsequently, metal plating is applied to the nucleus forming portion to form a plating film deeply entering the cavities. Thereafter, the plating film is burned to form the electrode deeply entering the cavities.

Method of producing oxygen sensor element

A method for manufacturing an oxygen sensor unit of the type which includes at least a shaped body of a solid electrolyte, an inner electrode provided on an inside surface of the shaped body and exposed to a reference gas, an outer electrode provided on an outside surface of the shaped body and exposed to a gas to be measured, and a porous protective layer covering the outer electrode and a portion of the shaped body adjoining to said outer electrode wherein the solid electrolyte is made of a mixture of zirconia and a stabilizer therefor and is constituted of a sintered product of partially stabilized zirconia. The method is characterized in that the partially stabilized, sintered zirconia is obtained according to a high temperature sintering process which includes at least the step of sintering the mixture at a temperature of 1200&deg; C. or over for a duration of 2 to 6 hours wherein a value obtained by integrating a variation in the sintering temperature with the duration in the sintering process is in the range of 300 to 1500&deg; C.&middot;hour.

Method for manufacturing a gas sensor unit

Oxygen sensor element

An air-fuel ratio sensing element comprises a cup-shaped solid electrolyte with one end opened and the other end closed, an external electrode provided on an outer wall surface of the solid electrolyte so as to be exposed to measured gas, and an internal electrode provided on an inner wall surface of the solid electrolyte in a confronting relationship to the external electrode. A first insulating layer, made of a gas-permeable and nonconductive porous material, is provided on the external electrode at least in a region used for detecting of an air-fuel ratio. A second insulating layer is provided outside the first insulating layer and, a heater layer as provided between the first insulating layer and the second insulating layer.

Air-fuel ratio sensor

According to the present invention, an oxygen sensor element includes a solid electrolyte having a side surface at one side thereof, the side surface being contactable with a gas to be measured, a skeletal electrode provided on the side surface and having a plurality of pore portions, each of the pore portions passing through the skeletal electrode up to the solid electrolyte, and a reactive electrode made of a porous film and provided in each of the pore portions, a thickness of the porous film being smaller than that of said skeletal electrode. An area percentage (SH/SZ) which is a ratio of a total area (SH) of the reactive electrode to a total area (SZ) of the skeletal electrode and the reactive electrode is in a range from 10 to 50%, an average area (SA) of the pore portions is 100 .mu.m.sup.2 or less, a film thickness of the skeletal electrode is in a range from 1.5 to 4 .mu.m, and the film thickness of the reactive electrode is in a range from 0.6 to 1.5 .mu.m. The oxygen sensor element is superior in the heat resistance characteristics and the response characteristics.

A measuring electrode and a reference plate are formed on the front and rear surfaces, respectively, of the electrolytic plate. The vent plate is provided with a vent channel. The heater base comprises a heating element. The electrolytic plate is made of a green sheet of zirconium oxide consisting of 5 to 7 molar % Y.sub.2 O.sub.3 and 0 to 5 parts by weight of aluminum oxide. The average particle diameter of the zirconium oxide powder is less than 2.0 .mu.m. The green sheet of zirconium oxide has a thickness of 50 to 300 .mu.m. The heater base is made of a green sheet of aluminum oxide consisting of aluminum oxide powder having an average particle diameter of less than 1.0 .mu.m and 0 to 10 parts by weight of zirconium oxide or yttria-stabilized zirconium oxide. The green sheet of aluminum oxide is at least 4 times the thickness of the green sheet of zirconium oxide. To complete the oxygen sensor, these four components are sintered together at 1300.degree. to 1600.degree. C. to be integrated.

Oxygen sensor

An oxygen concentration detecting device has a solid electrolyte made of a partially stabilized zirconia on one face of which is formed a measuring electrode exposed to a gas to be measured and on the other face of which a standard electrode exposed to a standard gas. An oxygen concentration detecting device provided with a protecting layer covers the measuring electrode formed on the oxygen concentration detecting device on the face exposed to the gas to be measured, the protecting layer being made of a partially stabilized sintered material of a partially stabilized zirconia material having a specific surface area of not less than 3 m.sup.2 /g and not more than 6.4 m.sup.2 /g to which a divalent or trivalent metal oxide, such as yttria, is added.

Oxygen sensor and a process for production thereof

An oxygen concentration detector provides high durability by increasing the thermal stability of coating layers applied to an electrode face thereof. A catalyst layer is formed on an outer surface of an electrode at the analysis gas side of a partition wall made of an ion oxygen conductive ceramic for generating electromotive force according to the difference between the concentration of oxygen in the analysis gas and the concentration of oxygen in the reference gas. The catalyst layer is composed of heat resistant ceramic particles and a particulate metallic catalyst made of platinum, rhodium or the like, supported by the surface of the heat resistant ceramic particles. The catalyst layer is formed so that the catalyst is supported by the heat resistant support particles. The support particles are heat treated to grow to a particle size so that particle growth can be restrained when the support particles are exposed to the exhaust gas from an internal combustion engine. The outside of the electrode of the partition wall is covered with support particles having such heat treated large cohered catalyst particles, and good responsivity of the sensor is thereby maintained.

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Toyohashi, Japan

Toshitaka Saito