Ngk Insulators, Inc.

Ngk Ceramic Device Co., Ltd.

Sumiko Horisaka

Mika Murakami

Hiroki Fujita

Takashi Ito

Sang Jae Lee

Takayuki Sekiya

Shinji Fujisaki

Takeshi Omori

Naoya Saito

Yukimasa Mori

Tetsuya Ishikawa

Yuji Okuda

Aya Sato

San Jae Lee

Kosuke Nakagawa

Provided is a gas sensor free from an unbonded space being in communication with an internal space. A gas sensor, which includes a sensor element including a plurality of layers that are bonded and formed of an oxygen-ion conductive solid electrolyte and which reduces a predetermined gas component of a measurement gas to identify a concentration of the gas component on the basis of a current flowing through the solid electrolyte, includes an internal space in which a measurement gas having the ability to reduce the gas component is provided. Of the plurality of layers, an interlaminar bonding layer, which bonds a layer forming a bottom surface of the internal space and a layer forming a side surface of the internal space, projects into the internal space.

Gas sensor

A sensor elementof a gas sensorincludes a blocking portionincluding an outer blocking layerthat is formed to cover, in an upper surface of a multilayer body, at least a part of an upper closest regionwhere an outer pump electrodeis not disposed and a distance up to a third inner cavityis minimal. The outer blocking layerdoes not have conductivity for one or more among various types of substances containing oxygen. The outer blocking layeris disposed between a lead linefor the outer pump electrode and the upper surface of the multilayer body to provide insulation therebetween, and is disposed between an upper connector padand the upper surface of the multilayer body to provide insulation therebetween. A porous protective layercovers the outer pump electrode

Sensor element and gas sensor

A gas sensor including an internal space, a first electrode, a second electrode, a pumping cell, a third electrode, a fourth electrode, a measuring cell, and a porous diffusion layer. The first and third electrodes, and the second and fourth electrodes are formed inside and outside the internal space, respectively. The pumping cell includes the first and second electrodes, and the measuring cell includes the third and fourth electrodes. The pumping cell pumps oxygen from the internal space when a predetermined voltage is applied between the first and second electrodes. The third electrode reduces an oxide gas component in a predetermined gas component to which a predetermined diffusion resistance has been applied by the porous diffusion layer. The measuring cell measures current flow between the third and fourth electrodes when a voltage corresponding to the degree of reduction in the third electrode is applied between the third and fourth electrodes.

A gas sensor including a sensor element constituted by an oxygen-ion conductive solid electrolyte as a main component and detecting a predetermined gas component in a measurement gas includes: an external communication part having an opening opened to the outside, and introducing the measurement gas from the outside under a predetermined diffusion resistance; an internal space communicating with the external communication part; a first electrode formed on a surface of the internal space; a second electrode formed in a space different from the internal space; and a pumping cell operable to pump out oxygen existing in the internal space when a predetermined voltage is applied between the first electrode and the second electrode. The thickness of the external communication part is 50% or more and 100% or less of the thickness of the internal space.

A NOx sensorincludes a sensor deviceand a heatercapable of heating the sensor device. The sensor deviceincludes an inner pump electrodeand an outer pump electrodedisposed respectively on the inner side and the outer side of a solid electrolyte layer. The sensor devicedetects the concentration of NOx by introducing a gas to be measured into a first inner vacancy, pumping out oxygen in the gas to be measured from the inner pump electrodeto the outer pump electrode, introducing the gas to be measured, from which the oxygen has been pumped out, into a second inner vacancy, reducing the NOx in the gas to be measured, to thereby generate oxygen, and detecting the generated oxygen. A characteristic stabilizing layercovers the outer pump electrodeand is made of a porous body with a thickness of 10 to 200 &#x3bc;m and a thickness variation of 20% or less.

Gas sensor and method for manufacturing same

A method of processing a sensor element includes the steps of: (a) preparing a gas atmosphere containing hydrocarbon, having an air-fuel ratio of 0.80 to 0.9999, and having a small amount of oxidizing gas added thereto; and (b) subjecting a sensor element to a heat treatment in the gas atmosphere at a temperature of 500&#xb0; C. or higher for 15 minutes or longer. The sensor element includes an electrochemical pumping cell constituted of an oxygen-ion conductive solid electrolyte and an electrode having a NOx reduction ability. A NOx gas in a measurement gas is reduced or decomposed in the electrode. A NOx concentration in the measurement gas is obtained based on a current which flows in the electrochemical pumping cell at a time of the reduction or decomposition.

Method of processing sensor element and sensor element

A gas sensor includes an internal space, diffusion control part, pumping cell, and measuring cell. The diffusion control part communicates with the internal space and has a slit-like shape with a smaller thickness than that of the internal space. The pumping cell pumps out oxygen from the internal space when voltage is applied between a first electrode fowled on a surface of the internal space and a second electrode formed outside the internal space. The measuring cell measures a current flowing between a third and fourth electrodes when a voltage is applied between the third and fourth electrodes. The third electrode is formed in the diffusion control part, and can reduce an oxide gas component in a predetermined gas component to which a predetermined diffusion resistance has been applied by the diffusion control part. The fourth electrode is formed in a part different from the diffusion control part.

A gas sensor having a sensor element that includes an inner space for introducing a measurement gas therein from an external space and a pump cell which has a first electrode formed on a surface of the inner space and a second electrode formed in a space different from the inner space and is provided to pump oxygen out of the inner space by applying a predetermined voltage between the first electrode and the second electrode. Assuming that the length of the inner space in a short-side direction of the sensor element as viewed from the front end portion side thereof is xand the length of the inner space in a longitudinal direction of the sensor element as viewed from the front end portion side thereof is x, the following inequality is satisfied: 0.05&#x2266;xx&#x2266;0.25.

A gas sensor including a pump electrode and a method for manufacturing a conductive paste for forming the pump electrode. When the pump electrode constituting an electrochemical pump cell for adjusting an oxygen partial pressure inside a gas sensor to measure a concentration of a gas component in a measurement gas by a current-limiting method is formed of a cermet of a noble metal and an oxide having oxygen ion conductivity, the noble metal contains a first noble metal having a catalytic activity, and a second noble metal having a catalytic activity suppressing ability to suppress the catalytic activity of the first noble metal with respect to an oxide gas except for oxygen, and an abundance ratio of the second noble metal with respect to the first noble metal in a particle surface of the first noble metal existing in the pump electrode is to be 0.01 to 0.3.

Pumping electrode of gas sensor, method of manufacturing conductive paste, and gas sensor

A sensor for specifying a concentration of a predetermined gas component in a measurement gas on the basis of a current flowing in an electrolyte by decomposition of the predetermined gas component, includes an internal space; a reference gas space; a pumping cell capable of pumping out oxygen in the internal space by applying a predetermined voltage between a first electrode and a second electrode; and a measuring cell including third and fourth electrodes and measuring a current flowing when a voltage is applied between the third electrode and the fourth electrode; wherein the first electrode is formed of porous cermet consisted of a noble metal and an oxygen ion conductive solid electrolyte, and the porosity of the first electrode is greater than or equal to 10% and less than or equal to 50%.

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Nagoya, Japan

Sumiko Horisaka