Ngk Insulators, Inc.

Mika Murakami

Takayuki Sekiya

Kunihiko Yoshioka

Hiroki Fujita

Sumiko Horisaka

Takashi Ito

Takashi Hino

Koichi Masuda

Tomoya Seimori

Hironori Sakakibara

Naoya Saito

Sang Jae Lee

Shingo Sokawa

Yosuke Okabe

Kengo Takeuchi

Satoko Moriyama

A sensor element includes an element body having an elongate rectangular parallelepiped shape and including solid electrolyte layers with oxygen ion conductivity, an outer pump electrode disposed on a first surface of the element body, and a protective layer covering at least a part of a second surface of the element body on a side opposite to the first surface and including one or more exposed spaces (a lower space) to which the second surface is exposed.

Sensor element and gas sensor

A sensor element includes an element body having an elongate rectangular parallelepiped shape and including solid electrolyte layers with oxygen ion conductivity, an outer pump electrode disposed on a first surface of the element body, and a protective layer covering at least a part of the first surface of the element body and including one or more exposed spaces (an upper space) to which the first surface is exposed.

A sensor element includes an element body having an elongate rectangular parallelepiped shape and including solid electrolyte layers with oxygen ion conductivity, an outer pump electrode disposed on a first surface of the element body, and a protective layer covering at least a part of the first surface of the element body and including one or more spaces (an upper space) that are present apart from the first surface in a direction perpendicular to the first surface.

A sensor element includes an element body having an elongate rectangular parallelepiped shape and including solid electrolyte layers with oxygen ion conductivity, an outer pump electrode disposed on a first surface of the element body, and a protective layer covering at least a part of a second surface of the element body on a side opposite to the first surface and including one or more spaces (a lower space) that are present apart from the second surface in a direction perpendicular to the second surface.

In a sensor element, a fourth diffusion rate-controlling portion includes a diffusion rate-controlling portion. The diffusion rate-controlling portion is formed between one or more and three or less surfaces, e.g., an upper surface, of upper, lower, left and right inner peripheral surfaces of a measurement-object gas flowing portion and a partition wall. A measurement electrode is formed on one, e.g., a lower surface, of upper, lower, left and right inner peripheral surfaces of a third inner cavity, the one surface being different in orientation from the Csurface along which the diffusion rate-controlling portion is formed. The diffusion rate-controlling portion and the measurement electrode may be formed on surfaces opposite to each other. A distance L between the measurement electrode and the diffusion rate-controlling portion may be 0.1 mm or more.

A gas sensor includes a sensor element that includes a gas inlet through which a measurement target gas is introduced into the sensor element and a protective cover that contains a substance having a capability of decomposing ammonia. The protective cover has a gas-contact surface area within a range of 450 mmto 1145 mm, the gas-contact surface area being a sum of a surface area of a portion facing the inlet-side gas flow path and a surface area of a portion facing an in-element-chamber flow path of the sensor element chamber that is a shortest flow path for the measurement target gas from the element-chamber inlet to the gas inlet.

Gas sensor

The gas sensorhas a gas flow channelformed therein by an inner protection cover. The gas flow channelis formed in the pathway of measured gas from a first outer gas holeformed in an outer protection coverthat covers the tip end of a sensor elementto a gas inlet portof the sensor element. The gas flow channelextends from the rear end side to the tip end side of the sensor elementand is open to the sensor element chamberhaving the gas inlet portdisposed therein.

Gas sensor with flow channel formed by inner protective cover

First inner gas holesand first outer gas holesof a gas sensor are formed so that the following conditions are satisfied: a first-inner-hole count Nin&#x2267;3, 0&#x3c;an inner/outer hole count ratio Nr&#x2266;0.5, and 0&#x3c;an inner/outer hole-area ratio Ar&#x2266;0.25, where the first-inner-hole count Nin represents the number of first inner gas holes, a first-inner-hole average area Ain [mm] represents (the total opening area of the first inner gas holes)/(the first-inner-hole count Nin), a first-outer-hole count Nout represents the number of the first outer gas holes, a first-outer-hole average area Aout represents (the total opening area of the first outer gas holes)/(the first-outer-hole count Nout), the inner/outer hole count ratio Nr represents the first-inner-hole count Nin/the first-outer-hole count Nout, and the inner/outer hole-area ratio Ar represents the first-inner-hole average area Ain/the first-outer-hole average area Aout.

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

In a gas sensor, a ratio A/Adefined by a ratio of an opening area Aper first inner gas hole and an opening area Aper second inner gas hole is set to higher than or equal to 0.9 and lower than or equal to 3.8 and, more preferably, to higher than or equal to 1.5 and lower than or equal to 1.9. Accordingly, adhesion of water to a sensor element can be sufficiently prevented. In addition, a ratio B/Bdefined by a ratio of a total opening area Bof the first inner gas holes to a total opening area Bof the second inner gas holes is set to higher than or equal to 0.85 and, more preferably, higher than or equal to 1.5. Accordingly, adhesion of water to the sensor element can be more reliably, effectively prevented.

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 gas sensor is provided with a multilayer body of solid electrolyte layers, a measurement electrode, a reference electrode, a reference gas introduction layer, a detection unit and a heater. The reference electrode and the measurement electrode are formed directly on the same first solid electrolyte layer. Thus, heat from the heater is transferred from a third substrate layer to the first solid electrolyte layer, and also to the reference electrode and the measurement electrode through the same first solid electrolyte layer. The reference electrode is covered with a reference gas introduction layer, formed of a porous body. The transference of heat from the heater to the reference electrode through the reference gas introduction layer is smaller than the transference of heat from the heater to the reference electrode through the first solid electrolyte layer on which the reference electrode is formed directly.

Growing community of inventors

Nagoya, Japan

Mika Murakami