Abstract: 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.

Abstract: A sensor element 101 of a gas sensor 100 includes a blocking portion 65 including an outer blocking layer 67 that is formed to cover, in an upper surface of a multilayer body, at least a part of an upper closest region 6a where an outer pump electrode 23 is not disposed and a distance up to a third inner cavity 61 is minimal. The outer blocking layer 67 does not have conductivity for one or more among various types of substances containing oxygen. The outer blocking layer 67 is disposed between a lead line 93 for the outer pump electrode and the upper surface of the multilayer body to provide insulation therebetween, and is disposed between an upper connector pad 91 and the upper surface of the multilayer body to provide insulation therebetween. A porous protective layer 24 covers the outer pump electrode 23.

Abstract: A sensor element 101 of a gas sensor 100 includes a blocking portion 65 including an outer blocking layer 67 that is formed to cover, in an upper surface of a multilayer body, at least a part of an upper closest region 6a where an outer pump electrode 23 is not disposed and a distance up to a third inner cavity 61 is minimal. The outer blocking layer 67 does not have conductivity for one or more among various types of substances containing oxygen. The outer blocking layer 67 is disposed between a lead line 93 for the outer pump electrode and the upper surface of the multilayer body to provide insulation therebetween, and is disposed between an upper connector pad 91 and the upper surface of the multilayer body to provide insulation therebetween. A porous protective layer 24 covers the outer pump electrode 23.

Abstract: A gas sensor includes a blocking portion 65 including an inner blocking layer 66 and outer blocking layer 67. The inner blocking layer 66 covers at least part of an exposed portion where solid-electrolyte layers are exposed as inner surfaces of a third internal cavity 61. The outer blocking layer 67 covers at least part of a nearest portion 6a that is at the shortest distance from the third internal cavity 61 among portions of outer surfaces of a multilayer structure where the solid-electrolyte layers are exposed. The inner blocking layer 66 and the outer blocking layer 67 do not each conduct one or more kinds of substances that contain oxygen.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A NOx sensor 100 includes a sensor device 110 and a heater 70 capable of heating the sensor device 110. The sensor device 110 includes an inner pump electrode 22 and an outer pump electrode 23 disposed respectively on the inner side and the outer side of a solid electrolyte layer 6. The sensor device 110 detects the concentration of NOx by introducing a gas to be measured into a first inner vacancy 20, pumping out oxygen in the gas to be measured from the inner pump electrode 22 to the outer pump electrode 23, introducing the gas to be measured, from which the oxygen has been pumped out, into a second inner vacancy 40, reducing the NOx in the gas to be measured, to thereby generate oxygen, and detecting the generated oxygen. A characteristic stabilizing layer 24 covers the outer pump electrode 23 and is made of a porous body with a thickness of 10 to 200 ?m and a thickness variation of 20% or less.

Abstract: 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° 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 x1 and the length of the inner space in a longitudinal direction of the sensor element as viewed from the front end portion side thereof is x2, the following inequality is satisfied: 0.05?x1/x2?0.25.

Abstract: 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.

Abstract: 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%.

Abstract: 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° 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.

Abstract: 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.

Abstract: 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.

Abstract: A NOx sensor 100 includes a sensor device 110 and a heater 70 capable of heating the sensor device 110. The sensor device 110 includes an inner pump electrode 22 and an outer pump electrode 23 disposed respectively on the inner side and the outer side of a solid electrolyte layer 6. The sensor device 110 detects the concentration of NOx by introducing a gas to be measured into a first inner vacancy 20, pumping out oxygen in the gas to be measured from the inner pump electrode 22 to the outer pump electrode 23, introducing the gas to be measured, from which the oxygen has been pumped out, into a second inner vacancy 40, reducing the NOx in the gas to be measured, to thereby generate oxygen, and detecting the generated oxygen. A characteristic stabilizing layer 24 covers the outer pump electrode 23 and is made of a porous body with a thickness of 10 to 200 ?m and a thickness variation of 20% or less.

Abstract: A gas sensor capable of a high-accuracy measurement which is realized by a high responsiveness and a strength that prevents a sensor element from being damaged by a stress occurring in assemblage and usage. This gas sensor includes a sensor element formed of an oxygen-ion conductive solid electrolyte as a main component, and the sensor element includes: an internal space to which a measurement gas is introduced from the outside; 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 including the first and second electrodes. The pumping cell is operable to pump out oxygen existing in the internal space when a predetermined voltage is applied to between the first and second electrodes. The thickness of the internal space is 50 ?m or more and 180 ?m or less.