JP2005156465A - Solid electrolyte type gas sensor, solid electrolyte type gas sensor structure, and gas concentration measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte type gas sensor and a gas concentration measuring apparatus of high measuring precision and measuring sensitivity for a gas concentration reduced in temperature differences between both faces and on the same face of a solid electrolyte substrate inside, in a limiting current type gas sensor using a solid electrolyte substrate. <P>SOLUTION: This limiting current type solid electrolyte gas sensor has the solid electrolyte substrate formed with a pair of electrode films on its both faces, a gas diffusion rate-limiting part forming substrate with at least one portion joined directly onto the first face of the solid electrolyte substrate or via other member arranged in an outer circumference of the electrode films to form a gas diffusion rate-limiting hole, and a gas flow part forming substrate with at least one portion joined directly onto the second face of the solid electrolyte substrate or via other member arranged in the outer circumference of the electrode films to form a gas flow hole, and the gas diffusion rate-limiting part forming substrate and the gas flow part forming substrate are a ceramic substrate or a porous substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solid electrolyte gas sensor, a solid electrolyte gas sensor structure, and a gas concentration measuring device. More specifically, the present invention relates to a limiting current type solid electrolyte gas sensor, a solid electrolyte gas sensor structure, and a gas concentration measuring device.

  In recent years, as a method for measuring gas concentration, a method utilizing a solid electrolyte having ion conductivity has been developed and put into practical use. As a method for measuring a gas concentration using a solid electrolyte, a limiting current type and an electromotive force type are known.

  Japanese Patent Application Laid-Open No. 2000-193637 discloses a sensor structure of Conventional Example 1. The sensor structure of Conventional Example 1 has a limiting current type solid electrolyte gas sensor which is a hydrocarbon sensor. FIG. 16 is a cross-sectional view of the sensor portion 751 of the sensor structure of Conventional Example 1. A sensor unit 751 that is a hydrocarbon sensor includes a solid electrolyte substrate 711, a ceramic substrate 712 (heater substrate), and an auxiliary substrate 713.

  The solid electrolyte substrate 711 is formed of an oxide of Ba, Ce, and Gd and has proton conductivity. The solid electrolyte substrate 711 has a cathode electrode film 722 and an anode electrode film 721. The ceramic substrate 712 and the auxiliary substrate 713 are made of partially stabilized zirconia ceramics. A ceramic substrate 712 is bonded to the anode electrode film 721 side of the solid electrolyte substrate 711 with an inorganic adhesive 723. The gas diffusion rate limiting hole 725 is an opening formed in a part of the inorganic adhesive 723. Reference numeral 726 denotes an anode electrode chamber. The ceramic substrate 712 (heater substrate) has a heating element 714 on the surface side not facing the anode electrode film 721. The heating element 714 is obtained by printing and baking a platinum paste. An auxiliary substrate 713 is bonded to the surface of the ceramic substrate 712 having the heating element 714 with an inorganic adhesive 724.

  The hydrocarbon sensor of Conventional Example 1 uses materials having substantially the same thermal expansion coefficient for the solid electrolyte substrate 711, the ceramic substrate 712, and the auxiliary substrate 713, and is considered so that thermal stress between the substrates does not occur during heating. . An auxiliary substrate 713 is bonded to the surface of the heating element 714 of the ceramic substrate 712 so that the ceramic substrate 712 is not damaged when the temperature is raised.

  FIG. 17 is an exploded perspective view of the sensor structure of Conventional Example 1. FIG. 17, 753 is a ceramic cylinder (sensor mounting member), 752 is a flat portion communicating with the ceramic cylinder 753, 754 is a lead wire, 761 is a metal case, 762 is a metal can, and 763 is a vent hole. , 755 is a metal lid, and 765 is an external lead wire.

  The sensor part 751 is joined to the flat part 752 with an inorganic adhesive. The sensor output and heater lead wires 754 are passed through the ceramic cylinder 753, and the lead wires 754 are electrically connected to external lead wires 765 drawn from the rear of the metal lid 755, respectively. Yes. The ceramic cylinder 753 is attached to a metal lid 755 via a lead wire 754. The ceramic cylinder 753 is housed in a metal case 761, and is fixed by fastening the metal lid 755 and the metal case 761 with a screw portion. A metal can 762 whose other end is sealed is joined to the metal case 761. The metal can 762 has a vent hole 763 for passing gas at a position corresponding to the sensor portion 751.

Next, the operation of the sensor structure of Conventional Example 1 will be described. A constant voltage is applied to the anode electrode film 721 and the cathode electrode film 722. The solid electrolyte substrate 711 is heated and activated by the heating element 714. The hydrocarbon gas in the atmosphere diffuses and moves to the anode electrode chamber 726 through the vent hole 763 and the gas diffusion rate controlling hole 725. A hydrocarbon gas corresponding to the hydrocarbon gas partial pressure in the atmosphere is supplied to the anode electrode chamber 726 by diffusion. The hydrocarbon gas introduced into the anode electrode chamber 726 is dissociated on the surface of the anode electrode film 721 to generate protons (meaning H ⁺ ). Protons move through the solid electrolyte substrate 711 toward the cathode electrode film 722 and are released as hydrogen molecules at the cathode electrode film 722. A current proportional to the amount of protons per unit time flowing through the solid electrolyte substrate 711 flows between the electrode films. Since the amount of this current is proportional to the hydrocarbon gas partial pressure in the atmosphere, the concentration of the hydrocarbon gas can be measured.

  Japanese Patent Laid-Open No. 2001-21533 discloses a solid electrolyte gas sensor of Conventional Example 2. FIG. 18 is a cross-sectional view of a gas sensor element of a solid electrolyte gas sensor of Conventional Example 2. The gas sensor element of Conventional Example 2 is an electromotive force type. In FIG. 18, 811 is a solid electrolyte made of an alkali metal ion conductor, 812 is a detection electrode made of alkali metal carbonate, 813 is a reference electrode made of an alkali metal complex oxide, and 822 is a detection electrode 812 and a reference electrode 813, respectively. The provided collector electrode, 824 is a lead wire attached to the collector electrode 822, 814 is a panel heater disposed outside the detection electrode 812 and the reference electrode 813, and 821 constitutes a heating part of the panel heater 814. A heating element, 823 is a heater lead wire.

The solid electrolyte 811 is heated by a panel heater 814 from both sides and operated. An electromotive force is generated between the detection electrode 812 and the reference electrode 813, and the gas concentration can be measured by the electromotive force extracted from the current collecting electrode 822. Since the solid electrolyte 811 is heated from both sides, both sides of the solid electrolyte 811 are heated to substantially the same temperature, and the measurement accuracy of the gas concentration can be improved.
JP 2000-193637 A (page 2-6, FIGS. 1 and 4) JP 2001-21533 A (page 2-4, FIG. 1)

  In the hydrocarbon sensor of Conventional Example 1, the amount of protons that move in the solid electrolyte substrate 711 from the anode electrode film 721 to the cathode electrode film 722 side depends on the conductivity of the solid electrolyte substrate 711. FIG. 19 shows an Arrhenius plot of the conductivity of stabilized zirconia, which is often used as a solid electrolyte substrate of a solid oxide gas sensor. In FIG. 19, the horizontal axis represents a value obtained by multiplying the reciprocal of the absolute temperature T (K) of stabilized zirconia by 1000, and the vertical axis represents the conductivity (S / cm). The conductivity of stabilized zirconia is larger as the temperature is higher. That is, the higher the temperature, the larger the proton conductivity and the easier the current flows. Other solid electrolytes have similar characteristics. Therefore, in order to obtain a highly accurate measurement value of the gas concentration by using the solid electrolyte for the gas sensor, it is necessary to control the temporal and spatial distribution of the temperature of the solid electrolyte within about ± 5 ° C.

  In the hydrocarbon gas sensor of Conventional Example 1, the heating element 714 is disposed only on one side of the solid electrolyte substrate 711. Therefore, when the sensor unit 751 is actually manufactured and operated, both sides of the solid electrolyte substrate 711 are 40 ° C. A temperature difference of ˜50 ° C. occurred. For this reason, the measured current value deviated from the true value, or the current value continuously measured in the gas flow having a constant concentration changed with time. Actually, when the entire sensor part 751 was inserted into a tubular furnace using a quartz glass tube, the temperature of both surfaces of the solid electrolyte substrate 711 was made the same, and the same measurement was performed, the measured current value did not vary. .

  In the solid electrolyte gas sensor of Conventional Example 2, an ion conductor of barium, cerium, zirconium, and indium oxide having a size of 10 mm × 10 mm × 0.5 mm (thickness) is used as the solid electrolyte 811, and each point of the solid electrolyte 811 is used. The temperature at was measured. Although the temperature was substantially the same between the same positions on both surfaces of the solid electrolyte 811 facing each other, in the same surface, the center portion showed the highest temperature, and the temperature decreased toward the periphery. When the temperature at a position 1.5 mm from the corner of the solid electrolyte base 811 was controlled at 350 ° C., the central portion was 380 ° C., and a temperature difference of 30 ° C. was generated.

For example, the conductivity when the temperature of the stabilized zirconia is 400 ° C. is 2 × 10 ⁻⁴ (S / cm), and the conductivity when the temperature is 430 ° C. is 3.7 × 10 ⁻⁴ (S / cm) ( (See FIG. 19). Therefore, in the solid electrolyte gas sensor of Conventional Example 2, the conductivity changes 1.85 times between the central portion and the end portion of the solid electrolyte 811, and protons or oxide ions are mainly in the central portion of the solid electrolyte 811. It was not flowing. For example, even when a solid electrolyte substrate having a size of 10 mm × 10 mm is used, only the central portion functions as a gas sensor, and the gas concentration measurement sensitivity may be lowered. When the rate of temperature increase of the solid electrolyte substrate is about 10 ° C./min or more, there is a risk that the solid electrolyte substrate may be broken due to a temperature difference in the solid electrolyte substrate.

The present invention solves the above-described conventional problems. In a limiting current type gas sensor using a solid electrolyte substrate, the temperature difference between both surfaces inside the solid electrolyte substrate is reduced, and the measurement accuracy and sensitivity of the gas concentration are reduced. An object of the present invention is to provide a solid electrolyte type gas sensor, a solid oxide type gas sensor structure, and a gas concentration measuring device that are high in the gas concentration.
The present invention relates to a limiting current type gas sensor using a solid electrolyte substrate, which reduces the temperature difference between both surfaces of the solid electrolyte substrate and within the same surface, and has high gas concentration measurement accuracy and measurement sensitivity. An object is to provide a sensor, a solid electrolyte gas sensor structure, and a gas concentration measuring device.

The invention according to claim 1 is a solid electrolyte substrate in which a pair of electrode films are formed on both sides, and another member disposed directly on the first surface of the solid electrolyte substrate or on the outer periphery of the electrode film. At least partly bonded to form a gas diffusion rate controlling hole, a gas diffusion rate controlling portion forming substrate, and at least via another member disposed directly on the second surface of the solid electrolyte substrate or on the outer periphery of the electrode film A gas flow-portion-forming substrate partially bonded to form a gas flow hole, wherein the gas diffusion-controlling portion-forming substrate and the gas flow-portion-forming substrate are a ceramic substrate or a porous substrate, This is a limiting current type solid electrolyte gas sensor.
The gas diffusion rate controlling hole may be a gap provided between the ceramic substrate and the solid electrolyte substrate, an opening provided in the ceramic substrate itself or a hole in the porous substrate, and it is easy to diffuse the detection gas for measuring the gas concentration, Larger molecular sizes are difficult to diffuse. The gas flow hole may be a gap provided between the ceramic substrate and the solid electrolyte substrate, an opening provided in the ceramic substrate itself, or a hole in the porous substrate.

According to the second aspect of the present invention, the gas diffusion rate controlling part forming substrate and the gas flow part forming substrate are formed of the same material, and the thermal expansion coefficient of the material is ± 20% of the thermal expansion coefficient of the solid electrolyte substrate. The solid oxide gas sensor according to claim 1, wherein
According to the present invention, the solid electrolyte substrate can be heated equally from both sides. Since the thermal expansion coefficients of the gas diffusion rate controlling part forming substrate and the gas flow part forming substrate are equal and approximate to the thermal expansion coefficient of the solid electrolyte substrate, it is possible to realize a solid electrolyte type gas sensor that is not easily damaged due to temperature changes. A highly reliable solid electrolyte type gas sensor capable of rapid heating or cooling can be realized from the solid electrolyte type gas sensor of the conventional example. The solid electrolyte gas sensor of Conventional Example 2 is an electromotive force type gas sensor. In that configuration, the material formed on both surfaces of the solid electrolyte substrate is not a material applied for the purpose of heating both surfaces of the solid electrolyte substrate uniformly, but a material for measuring the target gas concentration. . Conventional Example 2 is based on an idea that is fundamentally different from the configuration of the present invention.

  According to a third aspect of the present invention, a planar heater substrate is disposed in close contact with the surfaces of the gas diffusion rate controlling portion forming substrate and the gas flow portion forming substrate that do not face the solid electrolyte substrate. The solid electrolyte gas sensor according to claim 1 or 2, wherein the gas sensor is a solid electrolyte gas sensor. By heating the solid electrolyte substrate equally from both sides, the temperature difference between both sides of the solid electrolyte substrate can be reduced. The present invention can realize a solid electrolyte gas sensor having high measurement accuracy.

According to a fourth aspect of the present invention, there is provided a first heat conductive substrate disposed in close contact with the upper and lower substrates between the gas diffusion rate controlling portion forming substrate and the heater substrate, and the gas circulation portion. A second good heat conductive substrate disposed in close contact with the upper and lower substrates between the formation substrate and the heater substrate, and the first and second good heat conductive substrates. 4. The solid electrolyte gas sensor according to claim 3, wherein the thermal conductivity is higher than the thermal conductivity of the gas diffusion rate controlling part forming substrate and the gas flow part forming substrate.
Since heat from the heater substrate is uniformly transmitted to the entire solid electrolyte substrate through the highly heat conductive substrate, the temperature difference between both surfaces of the solid electrolyte substrate and the temperature difference between the central portion and the peripheral portion in the same surface can be reduced.

  According to a fifth aspect of the present invention, the size of the heater substrate and / or the size of the first and second good thermal conductive substrates are determined depending on whether the solid electrolyte substrate, the gas diffusion rate controlling portion forming substrate, or the gas is used. 5. The solid electrolyte gas sensor according to claim 3, wherein the gas sensor is larger than the flow part forming substrate. Generally, the temperature of the outer peripheral part of a heater substrate and the 1st and 2nd good heat conductive board | substrate becomes lower than the temperature of those center part. In the present invention, the heater substrate and / or the first and second good heat conductive substrates are enlarged so that they face the solid electrolyte substrate, the gas diffusion rate limiting portion forming substrate, and the gas flow portion forming substrate. In FIG. 2, the entire surface is at a substantially uniform temperature. Thereby, the temperature difference of the center part and peripheral part in the same surface of a solid electrolyte substrate can be made small.

  The invention according to claim 6 is the solid electrolyte gas sensor according to any one of claims 3 to 5, wherein the heater substrate is made of a highly heat conductive material. . Thereby, the temperature difference of the center part and peripheral part in the same surface of a solid electrolyte substrate can be made small.

  The invention described in claim 7 is characterized in that the first and second good thermal conductive substrates have a thermal conductivity of 20 W / m · K or more. A solid electrolyte gas sensor according to claim. Thereby, the temperature difference of the center part and peripheral part in the same surface of a solid electrolyte substrate can be made small.

  The invention according to claim 8 is characterized in that the first and second heat-conductive substrates are alumina or ceramics mainly composed of alumina, beryllia ceramics, aluminum nitride ceramics, silicon carbide ceramics, aluminum, copper or high quality. The solid electrolyte gas sensor according to any one of claims 4 to 7, wherein the solid electrolyte gas sensor is formed of a graphite sheet.

According to a ninth aspect of the present invention, there is provided a third highly heat conductive substrate that is in close communication with the respective surfaces of the gas diffusion rate controlling portion forming substrate and the gas flow portion forming substrate that are not opposed to the solid electrolyte substrate. The planar heater substrate is disposed in close contact with the first surface outside the third good heat conductive substrate or a surface parallel to the second surface. 1. The solid electrolyte gas sensor according to 1.
According to the present invention, the heater substrate is disposed on one side of the solid electrolyte substrate, and the solid electrolyte substrate is heated to a relatively uniform temperature from both sides, so that the temperature non-uniformity in the solid electrolyte substrate can be reduced. The “communication good thermal conductive substrate” is, for example, a substrate bent into a U-shape.

The invention according to claim 10 is the first good heat conductive substrate disposed in close contact with the surface of the gas diffusion rate controlling portion forming substrate that does not face the solid electrolyte substrate, and the gas circulation portion forming A second heat-conductive substrate disposed in close contact with the surface of the substrate that does not face the solid electrolyte substrate; and the gas diffusion rate-determining portion forming substrate of the first heat-conductive substrate is not opposed. A third good thermal conductive substrate that is in close communication with a side surface and a side of the second good thermal conductive substrate that does not face the gas flow portion forming substrate, and the third good thermal conductivity substrate, And a planar heater substrate arranged in close contact with a surface parallel to the first surface or the second surface outside the good heat conductive substrate, and the first good heat conductivity. The thermal conductivity of the substrate, the second good thermal conductivity substrate, and the third good thermal conductivity substrate is the gas diffusion rate limiting portion forming substrate, and Serial is a solid electrolyte gas sensor according to claim 1, wherein the greater than the thermal conductivity of the gas passage portion substrate.
According to the present invention, the heater substrate is disposed on one side of the solid electrolyte substrate, and the solid electrolyte substrate is heated to a relatively uniform temperature from both sides, so that the temperature non-uniformity in the solid electrolyte substrate can be reduced.

  The invention according to claim 11 is the size of each surface parallel to the first surface and the second surface of the third good heat conductive substrate and the size of the heater substrate, or the third good heat conductivity substrate. The sizes of the first surface and the second surface of the heat conductive substrate parallel to the second surface, the heater substrate, the first good heat conductive substrate, and the second good heat conductive substrate, 11. The solid electrolyte gas sensor according to claim 9, wherein the solid electrolyte gas sensor is larger than the solid electrolyte substrate, the gas diffusion rate controlling portion forming substrate, and the gas circulation portion forming substrate. Thereby, the temperature difference of the center part and peripheral part in the same surface of a solid electrolyte substrate can be made small.

According to a twelfth aspect of the present invention, the solid electrolyte substrate is formed of a barium / cerium / zirconium / indium oxide. A solid electrolyte gas sensor according to any claim.
According to the present invention, it is possible to realize a solid electrolyte gas sensor with high selectivity that can detect the hydrogen gas concentration in a reducing atmosphere.

According to a thirteenth aspect of the present invention, there is provided an anode electrode on one surface of a solid electrolyte substrate made of a ceramic material of a proton and an oxide ion conductor of barium / cerium / zirconium / indium oxide, and a cathode electrode on the other surface. A porous substrate or a ceramic substrate is joined so as to cover the anode electrode so that a gas diffusion rate controlling hole is formed or formed, and a gas flow hole is formed or formed. A porous substrate or a ceramic substrate is bonded so as to cover the other cathode electrode, and a heat conductive substrate having a size larger than that of the porous substrate or the ceramic substrate is formed on the outer surface of the porous substrate or the ceramic substrate. Disposed on both outer side surfaces of the good heat conductive substrate. A solid electrolyte type hydrogen gas sensors, characterized in that the planar heater's are disposed.
The present invention realizes a solid electrolyte type gas sensor that reduces the temperature difference between both surfaces of the solid electrolyte substrate and within the same surface, and has high gas concentration measurement accuracy and measurement sensitivity.
The ceramic material having a perovskite structure composed of an ion conductor of barium, cerium, zirconium, and indium oxide according to the present invention has almost proton conductivity and low oxygen ion conductivity. A highly selective hydrogen gas sensor can be realized by optimizing the hole diameter and length of the diffusion-controlled hole. In particular, a hydrogen gas sensor using a solid electrolyte material has not been realized in a reducing atmosphere, but hydrogen gas in a reducing atmosphere can be measured using the material of the present invention.

The invention according to claim 14 is characterized in that a heating element is arranged on the surface of the heater substrate so that the surface temperature is higher in the peripheral portion than in the central portion. The solid oxide gas sensor according to any one of claims 11 and 13.
According to the present invention, it is possible to further reduce the temperature difference between the central portion and the peripheral portion in the same plane of the solid electrolyte substrate. Therefore, a portion having a high electrical conductivity of the solid electrolyte substrate can be widened, and a solid electrolyte gas sensor with high detection sensitivity can be realized.

According to a fifteenth aspect of the present invention, each of the first and second heat-conductive substrates is composed of a first substrate and a second substrate, and the first substrate has a through hole in a central portion. The second substrate is fitted into the through hole, and the thermal conductivity of the first substrate is larger than the thermal conductivity of the second substrate. And a solid oxide gas sensor according to any one of claims 13 and 13.
According to the present invention, it is possible to further reduce the temperature difference between the central portion and the peripheral portion in the same plane of the solid electrolyte substrate. Therefore, a portion having a high electrical conductivity of the solid electrolyte substrate can be widened, and a solid electrolyte gas sensor with high detection sensitivity can be realized.

The invention according to claim 16 covers the whole with a heat insulating material having an opening portion communicating with the gas diffusion rate controlling hole and the gas flow hole, according to claims 3-5, 9-11 and 13 A solid electrolyte gas sensor according to any claim.
According to the present invention, it is possible to further reduce the temperature difference between both surfaces of the solid electrolyte substrate and the temperature difference between the central portion and the peripheral portion in the same plane. Therefore, a portion having a high electrical conductivity of the solid electrolyte substrate can be widened, and a solid electrolyte gas sensor with high detection sensitivity can be realized.

  The invention according to claim 17 is characterized in that the cross-sectional area of the gas flow hole is larger than the gas diffusion-controlling hole, and the solid according to any one of claims 1 to 5, 9 to 11 and 13 It is an electrolyte type gas sensor. Since the cross-sectional area of the gas flow hole is larger than the cross-sectional area of the gas diffusion-control hole, the solid electrolyte gas sensor is based only on the gas diffusion rate in the gas diffusion-control hole (the gas in the gas flow hole (for example, returned to the molecule) The current value can be measured without being affected by the diffusion rate of hydrogen).

  According to an eighteenth aspect of the present invention, the solid electrolyte type gas sensor according to any one of the first to seventeenth aspects of the present invention and the solid electrolyte type gas sensor are held, and are formed of a ceramic material and have a cylindrical shape. A sensor mounting member having a shape, a metal explosion-proof member covering the whole solid oxide gas sensor, a metal base member made of stainless steel having a cylindrical shape and attached to one end of the sensor mounting member, and the metal base member A lead terminal connected to the solid electrolyte gas sensor through the internal cavities of the sensor mounting member and the metal base member. Connected to one end of the electrode pin, and an external lead wire is connected to the other end of the electrode pin. A solid body characterized in that a peripheral portion and a mounting surface of the gas concentration detection device, the metal base member and the airtight terminal plate portion, and the airtight terminal plate and the insertion portion of the electrode pin are connected in an airtight state, respectively. It is an electrolyte type gas sensor structure. Since the gas sensor structure using the solid electrolyte of the present invention has a structure in which the sensor portion and the external lead wire portion can be shut off in an airtight state, the gas concentration in the atmosphere isolated from the outside world such as in a specific container or in a pipeline is low. In addition, a gas sensor that can measure the concentration of combustible gas, explosive gas, toxic gas, etc. or another gas in the gas can be realized.

  The invention according to claim 19 is the solid electrolyte type gas sensor structure according to claim 18, wherein the solid electrolyte type gas sensor is attached to the sensor attachment member while maintaining a gap. Highly accurate and low power consumption due to the structure in which heat is not easily transferred from the solid electrolyte gas sensor to the sensor mounting member, so there is little temperature difference between the two sides of the solid electrolyte substrate, and between the central part and the peripheral part in the same plane. The solid oxide gas sensor structure can be realized.

  The invention described in claim 20 is a solid electrolyte gas sensor according to any one of claims 1 to 17, a temperature control unit that heats the solid electrolyte substrate and controls the solid electrolyte substrate to a predetermined temperature, A voltage control unit for applying a predetermined voltage between the pair of electrode films; a current detection unit for detecting a current flowing between the pair of electrode films; and a gas concentration from at least the current detected by the current detection unit. A gas concentration measuring device comprising: a gas concentration calculating unit for calculating. The present invention realizes a highly accurate gas concentration measuring device.

According to the present invention, a limit current type solid electrolyte gas sensor, a solid electrolyte gas sensor structure, and a temperature difference between both surfaces inside a solid electrolyte substrate are small, and gas concentration measurement accuracy and measurement sensitivity are high. There is an effect that the gas concentration measuring device used can be realized.
According to the present invention, the limiting current type solid electrolyte type gas sensor, the solid electrolyte type gas sensor structure, which has a small temperature difference between both surfaces in the solid electrolyte substrate and within the same plane, and high gas concentration measurement accuracy and measurement sensitivity. The body and the gas concentration measuring device using the body can be realized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.
In all the following embodiments, a structure including a solid electrolyte substrate and two ceramic substrates is referred to as a sensor unit. A structure in which a good heat conductive substrate and / or a heater substrate is arranged outside the sensor portion is called a sensor block. A structure in which the sensor block is covered with a heat insulating material is called a sensor module.

Embodiment 1
A sensor unit and a sensor block according to the first embodiment of the present invention will be described with reference to FIGS. 1, FIG. 2, and FIG. 3 are a cross-sectional view, a perspective view, and an exploded perspective view, respectively, of the sensor unit according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of the sensor block according to the first embodiment of the present invention. In order to simplify the drawing, description of lead wires electrically connected to the cathode electrode film 111, the anode electrode film 112, and the heating elements 172a and 172b is omitted. The sensor block of the first embodiment detects gas (hydrogen) using a known limit current detection method.

  First, the sensor unit 101 according to the first embodiment will be described. The sensor unit 101 according to Embodiment 1 includes a solid electrolyte substrate 110, an anode electrode film 112, a cathode electrode film 111, an adhesive 116, an adhesive 117, a ceramic substrate 113a, and a ceramic substrate 113b.

  The anode electrode film 112 is formed on one surface of the solid electrolyte substrate 110, and the ceramic substrate 113b is bonded by an inorganic adhesive 116 applied to the outer peripheral portion (excluding the gas diffusion rate limiting hole 114). . A cathode electrode film 111 is formed on the other surface of the solid electrolyte substrate 110, and the ceramic substrate 113a is joined by an inorganic adhesive 117 applied to the outer periphery (excluding the gas flow holes 115). The ceramic substrates 113a and 113b have the same material or the same thermal expansion coefficient, size, and thickness. A gap is formed between the solid electrolyte substrate 110 and the ceramic substrates 113a and 113b. The distance between the solid electrolyte substrate 110 and the ceramic substrate 113a (in the first embodiment, 100 μm) is the distance between the solid electrolyte substrate 110 and the ceramic substrate 113b (in the first embodiment, 20 μm). Is greater than.)

  Reference numeral 118 denotes an electrode terminal portion electrically connected to the cathode electrode film 111 (see FIGS. 2 and 3). The electrode terminal portion 118 is disposed at one corner of the solid electrolyte substrate 110. Reference numeral 119 denotes an electrode terminal portion electrically connected to the anode electrode film 112. The electrode terminal portion 119 is disposed at a corner on the opposite side of the electrode terminal portion 118 of the solid electrolyte substrate 110. Lead wires (not shown) are connected to the electrode terminal portion 118 and the electrode terminal portion 119, respectively. The ceramic substrate 113a and the ceramic substrate 113b have notches and have a structure in which the lead wire does not hit the ceramic substrate 113a or 113b.

  The adhesive 116 is formed in a C-shape along the edge of the ceramic substrate 113b. The gas diffusion control hole 114 is a gap formed between the opening of the adhesive 116 and the ceramic substrate 113 b and the solid electrolyte substrate 110. The gas diffusion rate controlling hole 114 has a size (cross-sectional area and depth) that is easy to diffuse a detection gas (hydrogen gas in the first embodiment) for measuring the gas concentration, and that has a molecular size larger than that.

  The adhesive 117 is formed in a C-shape along the edge of the ceramic substrate 113a. The gas flow hole 115 is a gap formed between the opening portion of the adhesive 117 and the ceramic substrate 113 a and the solid electrolyte substrate 110. The cross-sectional area of the gas flow hole 115 is at least twice the cross-sectional area of the gas diffusion control hole 114. The length (depth) of the gas flow hole 115 is shorter than the length (depth) of the gas diffusion control hole 114. With this configuration, the gas generated in the cathode electrode film 111 is discharged from the gas flow hole 115 without any delay.

  Next, the sensor block 103 of Embodiment 1 will be described (see FIG. 4). The sensor block 103 includes a heater substrate 171b arranged outside the ceramic substrate 113b (anode electrode film 112 side) of the sensor unit 101, and a heater substrate 171a arranged outside the ceramic substrate 113a (cathode electrode film 111 side). is there. The planar heater substrates 171a and 171b are not bonded to the ceramic substrates 113a and 113b, but are only in close contact with each other. The heater substrates 171 a and 171 b have the same size and are larger than the size of the sensor unit 101. The heater substrate 171a has a heating element 172a on the outer surface thereof. The heater substrate 171b has a heating element 172b on the outer surface thereof. The heating element 172a and the heating element 172b are planar heaters. The rectangle defined by the outer circumferences of the heating elements 172a and 172b has a size larger than that of the sensor unit 101.

Next, materials and characteristics of each part constituting the sensor block 103 of Embodiment 1 will be described.
The size of the solid electrolyte substrate 110 is 10 mm × 10 mm × 0.4 mm (thickness), and is formed from a perovskite-type sintered body made of barium, zirconium, cerium, indium oxide. A perovskite-type sintered body made of barium, zirconium, cerium, and indium oxide is a material that conducts only protons. A platinum paste containing fine platinum powder is printed on both surfaces of the solid electrolyte substrate 110 by a thick film printing method, dried at a temperature of 150 ° C. for 10 minutes, and then fired at an optimum firing temperature and time for the platinum paste to be an anode electrode film. 112 and the cathode electrode film 111 were formed.

  The ceramic substrates 113a and 113b have a size of 10 mm × 10 mm × 0.5 mm (thickness) and are made of a forsterite material. The thermal expansion coefficient of the forsterite material is within ± 10% of the thermal expansion coefficient of the perovskite-type sintered body made of barium, zirconium, cerium, and indium oxide.

  As the adhesives 116 and 117, inorganic glass paste was used. On the upper surface of the ceramic substrate 113b, a paste obtained by mixing an inorganic glass paste with a spacer material for controlling the thickness of the gas diffusion rate controlling hole 114 was printed in the shape (adhesive 116) shown in FIG. The ceramic substrate 113b was positioned and pressed against the anode electrode film 112 side of the solid electrolyte substrate 110. Further, after drying at 150 ° C. for 10 minutes in that state, the ceramic substrate 113b was joined to the solid electrolyte substrate 110 by firing at an optimum firing temperature and time for the inorganic glass paste, and a gas diffusion rate controlling hole 114 was formed. The ceramic substrate 113a was joined to the cathode electrode film 111 side of the solid electrolyte substrate 110 by the same method as the joining method of the ceramic substrate 113b to form the gas flow holes 115.

  The size of the heater substrates 171a and 171b is 12 mm × 12 mm × 0.5 mm (thickness). As the heater substrates 171a and 171b, electrothermal mica substrates were used. A 0.05 mm thick iron-chromium metal foil (No. 4L, manufactured by Nippon Metal Industry Co., Ltd.) is formed in a zigzag manner on one side of the mica substrate for electric heating, and the heating element 172a (or 172b) is formed. It was. The heater blocks 171 a and 171 b were brought into close contact with the upper and lower surfaces of the sensor unit 101 to form the sensor block 103.

  The sensor module and sensor structure of Embodiment 1 will be described. The sensor module according to the first embodiment has a configuration in which the sensor block 104 in FIG. 13 (cross-sectional view of the sensor module 107 according to the eighth embodiment) is replaced with a sensor block 103. The sensor module of Embodiment 1 has a structure in which the sensor block 103 is covered with heat insulating materials 411 to 417. The sensor structure of the first embodiment has a configuration in which the sensor module 107 in FIGS. 14 and 15 (cross-sectional view of the sensor structure 108 of the eighth embodiment) is replaced with the sensor module of the first embodiment. The structure of the sensor module and the sensor structure (including the heat insulating materials 411 to 417, the sensor mounting member 513, and the metal base member 621) will be described in detail in Embodiment 8.

  The sensor module of Embodiment 1 was attached to the sensor attachment member 513 and the metal base member 621 (FIG. 15), and the temperature at each point on the solid electrolyte substrate 110 was measured. A temperature control thermocouple is placed at a position 1.5 mm from the corner of the solid electrolyte substrate 110, and a temperature measurement thermocouple is provided at the center of the ceramic substrate 113a on the cathode electrode film 111 side and the center of the ceramic substrate 113b on the anode electrode film 112 side. The pair was joined with Aaron ceramics (inorganic adhesive). The temperature detected by the thermocouple for temperature measurement attached to the ceramic substrates 113a and 113b is the temperature at the center of both surfaces of the solid electrolyte substrate 110 (the thermocouple cannot be attached because electrodes are formed). It is thought that it is almost the same.

  The temperature of the corner portion of the solid electrolyte substrate 110 (temperature detected by the thermocouple for temperature control) was controlled at 350 ° C., and the temperature was measured. As a result, the temperature difference between the central portions of the ceramic substrates 113a and 113b on the electrode film side was within 5 ° C. In the sensor part of Conventional Example 1 in which the heater substrate is arranged only on one side of the solid electrolyte substrate, the temperature difference between both sides of the solid electrolyte substrate was about 40 ° C. to 50 ° C., which was greatly improved.

  Further, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate 110 (the temperature detected by the thermocouple for temperature measurement attached to the central portion of the surface of the ceramic substrate facing the solid electrolyte substrate 110, and the solid electrolyte) The difference between the detected temperature (control temperature) of the thermocouple for temperature control attached to the end of the substrate 110 was about 25 ° C. In the solid electrolyte gas sensor of Conventional Example 2, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate was improved as compared with about 30 ° C.

  In the sensor block 103 of the first embodiment, heater substrates 171 a and 171 b having a size larger than that of the solid electrolyte substrate 110 are brought into close contact with both sides of the sensor unit 101. The heater substrate 171a and the heater substrate 171b were formed of the same material having the same thermal expansion coefficient as that of the solid electrolyte substrate 110. Since the sensor block 103 is configured in this way, the solid electrolyte substrate 110 can be heated equally from both sides, and the temperature spatial distribution can be made more uniform than in the prior art.

  Conventionally, since the temperature in the solid electrolyte substrate is not uniform, the solid electrolyte substrate can be destroyed if the rate of temperature rise at the start of gas concentration measurement or the rate of temperature decrease at the end of measurement is greater than about 10 ° C / min. There was sex. By using the sensor block 103 according to the first embodiment, the temperature increase / decrease rate can be set to 20 ° C./min or more, and a gas concentration measurement device capable of quickly measuring the gas concentration can be realized.

  Since the thermal expansion coefficients of the ceramic substrates 113a and 113b are within ± 10% of that of the solid electrolyte substrate and the heater substrates 171a and 171b and the sensor unit 101 are not joined (closely contacted), the adhesives 116 and 117 are fired. Alternatively, the solid electrolyte substrate 110 does not break when the sensor unit 101 is heated or lowered.

  The solid electrolyte substrate 110 of Embodiment 1 was formed from a ceramic material having a perovskite structure made of an ion conductor of barium, cerium, zirconium, and indium oxide. This material has high proton conductivity and low oxygen ion conductivity. Therefore, the sensor unit 101 of the first embodiment is useful as a sensor unit of a hydrogen gas sensor having high hydrogen gas selectivity. The sensor unit 101 of the first embodiment is useful as a sensor unit of a hydrogen gas sensor using a solid electrolyte material that can be used in a reducing atmosphere as in the measurement of the hydrogen concentration in natural gas.

  In the sensor unit 101 of the first embodiment, since the cross-sectional area of the gas flow hole 115 is larger than the cross-sectional area of the gas diffusion-controlling hole 114, the gas can be discharged from the gas flow hole 115 regardless of the molecular size, and the selectivity is improved. A highly sensitive gas sensor and gas concentration measuring device can be realized.

  Instead of the ceramic substrates 113a and 113b, a porous substrate formed of a porous material may be used, and gas may be passed through the pores of the porous material. In this case, the gas diffusion rate limiting hole 114 and the gas flow hole 115 are unnecessary, and a sensor unit with a simple configuration can be realized.

<< Embodiment 2 >>
The sensor unit according to the second embodiment of the present invention will be described with reference to FIG. It is sectional drawing of the sensor part of Embodiment 2 of this invention. The sensor unit 102 according to the second embodiment includes a solid electrolyte substrate 110, an anode electrode film 112, a cathode electrode film 111, an adhesive 154, an adhesive 155, a ceramic substrate 153a, and a ceramic substrate 153b. The sensor unit 102 of the second embodiment includes an adhesive 116, an adhesive 117, a ceramic substrate 113a, and a ceramic substrate 113b of the sensor unit 101 of the first embodiment, and an adhesive 154, an adhesive 155, a ceramic substrate 153a, and a ceramic substrate. 153b, the same reference numerals are used for the common parts, and the description is omitted.

  The adhesive 154, the adhesive 155, the ceramic substrate 153a, and the ceramic substrate 153b are respectively formed from the same material as the adhesive 116, the adhesive 117, the ceramic substrate 113a, and the ceramic substrate 113b.

  The ceramic substrate 153a has the same outer shape as the ceramic substrate 113a, and has a circular gas flow hole 157 at the center. The ceramic substrate 153b has the same outer shape as the ceramic substrate 113b, and has a circular gas diffusion control hole 156 in the center. The cross-sectional area of the gas flow hole 157 is larger than the cross-sectional area of the gas diffusion control hole 156. The gas diffusion control hole 156 has a size (cross-sectional area) in which a gas for measuring a gas concentration (hydrogen gas in the second embodiment) is easily diffused, and molecules having a larger molecular size are difficult to diffuse.

  The adhesive 154 is formed in an annular shape (the periphery is closed) along the edge of the ceramic substrate 153a. The adhesive 155 is formed in an annular shape (the periphery is closed) along the edge of the ceramic substrate 153b.

  As a result of performing the same temperature measurement as in the first embodiment using the sensor unit 102 in the second embodiment, the spatial distribution of the temperature in the solid electrolyte substrate 110 is more uniform than the conventional one, as in the first embodiment. It was confirmed that there was. The sensor unit 102 according to the second embodiment has the same effects as the sensor unit 101 according to the first embodiment.

<< Embodiment 3 >>
A sensor block according to Embodiment 3 of the present invention will be described with reference to FIGS. 6 and 7 are a sectional view and an exploded perspective view of a sensor block according to Embodiment 3 of the present invention. The sensor block of the third embodiment detects gas (hydrogen) using a known limit current detection method. The sensor block 104 of the third embodiment includes a heater substrate 171a having a heating element 172a, a good heat conductive substrate 201a, a sensor unit 101 (the sensor unit of the first embodiment), a good heat conductive substrate 201b, and a heating element 172b. The heater substrate 171b is provided. The difference from the sensor block 103 (FIG. 4) of the first embodiment is that a good heat conductive substrate 201a is arranged between the sensor unit 101 and the heater substrate 171a, and the good condition is obtained between the sensor unit 101 and the heater substrate 171b. This is the point where the thermally conductive substrate 201b is arranged. Since the other configuration is the same as that of the sensor block 103 of the first embodiment, the same reference numerals are used for common portions, and description thereof is omitted.

  The size of the good heat conductive substrates 201a and 201b is 12 mm × 12 mm × 0.5 mm, and is formed from a sintered body of aluminum nitride. The sintered body of aluminum nitride is a good thermal conductor and has a thermal conductivity of 170 W / m · K. The sizes of the thermally conductive substrates 201a and 201b are the same as the heater substrates 171a and 171b, and are larger than the size of the sensor unit 101 (10 mm × 10 mm). The good thermal conductive substrate 201a is not bonded to the heater substrate 171a and the ceramic substrate 113a, and is in close contact. The thermally conductive substrate 201b is not bonded to the heater substrate 171b and the ceramic substrate 113b, and is in close contact.

  For the sensor block 104 of the third embodiment, the temperature of the corner portion of the solid electrolyte substrate 110 was controlled at 350 ° C. as in the first embodiment, and the temperature was measured. As a result, the temperature difference between the central portions of the ceramic substrates 113a and 113b on the electrode film side was within 2 ° C. In the sensor part of Conventional Example 1 in which the heater substrate is arranged only on one side of the solid electrolyte substrate, the temperature difference between both sides of the solid electrolyte substrate was about 40 ° C. to 50 ° C., which was greatly improved.

  Further, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate 110 (the temperature detected by the thermocouple for temperature measurement attached to the central portion of the surface of the ceramic substrate facing the solid electrolyte substrate 110, and the solid electrolyte) The difference between the temperature control thermocouple attached to the edge of the substrate 110 and the detected temperature (control temperature) was about 15 ° C. ± 3 ° C. In the solid electrolyte gas sensor of Conventional Example 2, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate was about 30 ° C., which was improved to half.

  In the sensor block 104 of the third embodiment, the good thermal conductive substrates 201a and 201b having a size larger than the solid electrolyte substrate 110 and the heater substrates 171a and 171b are in close contact with both sides of the sensor unit 101. The heater substrate 171a and the heater substrate 171b were formed of the same material having the same thermal expansion coefficient as that of the solid electrolyte substrate 110. Since the sensor block 103 is configured in this way, the solid electrolyte substrate 110 can be heated equally from both sides, and the temperature spatial distribution can be made more uniform than in the prior art. The entire surface of the sensor unit could be heated from the heater substrate through the good heat conductive substrate.

  The heat conductivity of the good heat conductive substrates 201a and 201b is larger than that of the ceramic substrates 113a and 113b (forsterite substrate in the third embodiment, and the heat conductivity is 4 W / m · K). Heat from 171a and 171b can be efficiently conducted to the sensor unit 101. Actually, the thermal conductivity of the good thermal conductive substrate may be 20 W / m · K or more. It has been confirmed that when the alumina ceramic substrate (thermal conductivity: 23 W / m · K) is used as the good heat conductive substrates 201 a and 201 b, a sufficient effect can be obtained. Other than this, ceramic materials such as alumina or ceramics mainly composed of alumina, beryllia, aluminum nitride, silicon carbide, metal materials such as aluminum, copper, silver, and materials such as high-quality graphite sheets can be used as heat conductive substrates. 201a and 201b may be formed.

The thermal expansion coefficients of the ceramic substrates 113a and 113b are set to be within ± 10% of those of the solid electrolyte substrate 110, and the heater substrates 171a and 171b, the heat conductive substrates 201a and 201b, and the sensor unit 101 are not joined (closely contacted). Therefore, the solid electrolyte substrate 110 is not destroyed when the adhesives 116 and 117 are fired or when the temperature and temperature of the sensor unit 101 are increased or decreased.
Since the sensor block 104 of the third embodiment can make the temperature distribution in the solid electrolyte substrate 110 more uniform than the sensor block 101 of the first embodiment, a highly accurate gas sensor and gas concentration detection device can be realized.

In FIG. 6, the heater substrates 171a and 171b and the good heat conductive substrates 201a and 201b are larger than the solid electrolyte substrate 110 and the ceramic substrates 113a and 113b. Instead of this configuration, the size of the good thermal conductive substrates 201a and 201b is made larger than that of the solid electrolyte substrate 110 and the ceramic substrates 113a and 113b, and the size of the heater substrates 171a and 171b is set to be the solid electrolyte substrate 110 and the ceramic substrate 113a. , 113b. However, the configuration of FIG. 6 is preferable in order to reduce the temperature difference between the central portion and the end portion of the solid electrolyte substrate 110 in the same plane.
The size of the heater substrates 171a and 171b may be larger than that of the good thermal conductive substrates 201a and 201b.

<< Embodiment 4 >>
A sensor block according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view of a sensor block according to Embodiment 4 of the present invention. The sensor block of Embodiment 4 detects gas (hydrogen) using a known limit current detection method. The sensor block 105 according to the fourth embodiment includes a heater substrate 171b having a good heat conductive substrate 251, a sensor unit 101 (a sensor unit according to the first embodiment), and a heating element 172b communicating with each other. The difference from the sensor block 103 (FIG. 4) of the first embodiment is that a good thermal conductive substrate 251 communicated between the sensor unit 101 and the heater substrate 171b is disposed and the heater substrate 171a is removed. . Since the other configuration is the same as that of the sensor block 103 of the first embodiment, the same reference numerals are used for common portions, and description thereof is omitted.

The good thermal conductive substrate 251 has a U-shape and is disposed in close contact with the upper and lower surfaces of the sensor unit 101. A heater substrate 171b having a heating element 172b is closely attached to the outside of the good heat conductive substrate 251 (in the fourth embodiment, the anode electrode film 112 side). The good heat conductive substrate 251 is formed of a metal aluminum substrate (thermal conductivity: 236 W / m · K) having a thickness of 0.5 mm.
The surfaces of the good thermal conductive substrate 251 parallel to the anode electrode film 112 and the cathode electrode film 111 and the size of the heater substrate 171b are larger than those of the solid electrolyte substrate 110 and the ceramic substrates 113a and 113b.

  For the sensor block 105 of the fourth embodiment, the temperature of the corner portion of the solid electrolyte substrate 110 was controlled at 350 ° C. as in the first embodiment, and the temperature was measured. As a result, the temperature difference between the central portions of the ceramic substrates 113a and 113b on the electrode film side was within about 30 ° C. In the sensor part of Conventional Example 1 in which the heater substrate is arranged only on one side of the solid electrolyte substrate, the temperature difference between both sides of the solid electrolyte substrate was about 40 ° C. to 50 ° C., which was greatly improved. That is, although the heater substrate is attached to only one surface with respect to the solid electrolyte substrate 110, the heat from the heater substrate 171 b is transferred to the other surface of the solid electrolyte substrate 110 through the good heat conductive substrate 251. I was able to tell. The temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate 110 was slightly improved as compared with the conventional case.

The sensor block 105 of the fourth embodiment has a simple configuration and can reduce the temperature distribution in the solid electrolyte substrate 110 to some extent. Although the sensor block 105 cannot be used for a highly accurate gas sensor and gas concentration measuring device, a gas sensor and a gas concentration measuring device that do not require strict measurement accuracy such as determination of the presence or absence of a detection gas can be realized with a simple configuration.
In FIG. 8, the heater substrate 171b may be removed and the heater substrate 171a may be provided. The good heat conductive substrate 251 is disposed between the sensor unit 101 and the heater substrate 171a.

<< Embodiment 5 >>
The sensor block according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a sectional view of a sensor block according to the fifth embodiment of the present invention. The sensor block of Embodiment 5 detects gas (hydrogen) using a known limit current detection method. The sensor block 106 according to the fifth embodiment includes a good heat conductive substrate 264, a good heat conductive substrate 201a, a sensor unit 101 (a sensor unit according to the first embodiment), a good heat conductive substrate 201b, and a heating element 172b that communicate with each other. Has a heater substrate 171b.

  A difference from the sensor block 104 (FIG. 6) of the third embodiment is that a good heat conductive substrate 264 communicated with the good heat conductive substrate 201b and the heater substrate 171b is disposed, and the heater substrate 171a is removed. Is a point. Since the other configuration is the same as that of the sensor block 104 of the third embodiment, the same reference numerals are used for common portions, and description thereof is omitted.

The good heat conductive substrate 264 has a U-shape and is disposed in close contact with the outside of the good heat conductive substrates 201a and 201b. A heater substrate 171b having a heating element 172b is closely attached to the outside of the good heat conductive substrate 264 (in the fifth embodiment, on the anode electrode film 112 side). The good heat conductive substrate 264 is formed of a metal aluminum substrate (thermal conductivity: 236 W / m · K) having a thickness of 0.5 mm.
The surfaces of the good heat conductive substrate 264 parallel to the anode electrode film 112 and the cathode electrode film 111, the heater substrate 171b, and the good heat conductive substrates 201a and 201b are as follows: the solid electrolyte substrate 110, the ceramic substrates 113a and 113b. Bigger than.

  For the sensor block 106 of the fifth embodiment, as in the first embodiment, the temperature of the corner portion of the solid electrolyte substrate 110 was controlled at 350 ° C., and the temperature was measured. As a result, the temperature difference between the central portions of the ceramic substrates 113a and 113b on the electrode film side was within about 30 ° C. (similar to the fourth embodiment). Compared to the temperature difference between the two surfaces of the solid electrolyte substrate of about 40 ° C. to 50 ° C. in the sensor portion of Conventional Example 1 in which the heater substrate is disposed only on one side of the solid electrolyte substrate, the improvement was possible. That is, although the heater substrate is attached to only one surface with respect to the solid electrolyte substrate 110, the heat from the heater substrate 171b is transferred to the other surface of the solid electrolyte substrate 110 through the good heat conductive substrate 264. I was able to tell.

Further, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate 110 (the temperature detected by the thermocouple for temperature measurement attached to the central portion of the surface of the ceramic substrate facing the solid electrolyte substrate 110, and the solid electrolyte) The difference between the detected temperature (control temperature) of the thermocouple for temperature control attached to the end of the substrate 110 was about 25 ° C. Compared with the solid electrolyte type gas sensor of Conventional Example 2, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate was about 30 ° C., which was improved.
The sensor block 106 according to the fifth embodiment has a simple configuration and can reduce the temperature distribution in the solid electrolyte substrate 110 to some extent. The sensor block 106 according to the fifth embodiment has a simple configuration and can reduce the temperature distribution in the solid electrolyte substrate 110 to some extent. Although the sensor block 106 cannot be used for a highly accurate gas sensor and gas concentration measurement device, a gas sensor and a gas concentration measurement device that do not require strict measurement accuracy such as determination of the presence or absence of a detection gas can be realized with a simple configuration.
In FIG. 9, the heater substrate 171b may be removed and the heater substrate 171a may be provided. The good heat conductive substrate 264 is disposed between the good heat conductive substrate 201a and the heater substrate 171a.

<< Embodiment 6 >>
A heating element according to the sixth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a perspective view of a heating element according to the sixth embodiment of the present invention. The heating element 301 is formed in a spiral shape from an iron-chromium thin plate material (in the sixth embodiment, it is a metal foil No. 4L made by Nippon Metal Industry Co., Ltd. having a thickness of 0.05 mm). The interval between the spirals is wider toward the inner side (in the order of intervals 303, 304, and 305). Wide terminal portions 306 and 307 for connecting lead wires are provided at both ends of the heating element. By attaching the heating element 301 to the surface of the heater substrate, the surface temperature of the heater substrate itself is higher in the peripheral portion than in the central portion. The terminal part 306 and the terminal part 307 are bent at an angle of 90 degrees with respect to the heating element 301 and inserted into an opening (not shown) of the heater substrate. When the heating element 301 is brought into close contact with the heater substrate and electric power is supplied between the terminal portion 306 and the terminal portion 307, a sensor block having a smaller temperature difference between the peripheral portion and the central portion of the solid electrolyte substrate 110 can be realized.

  A sensor block is created by replacing the heating elements 172a and 172b of the sensor block 104 (FIG. 6) of the third embodiment with the heating element 301, and the temperature of the corner of the solid electrolyte substrate 110 is set to 350 ° C. as in the first embodiment. The temperature was measured. As a result, the temperature difference between the central portions of the ceramic substrates 113a and 113b on the electrode film side was within 2 ° C. (similar to the third embodiment). In the sensor part of Conventional Example 1 in which the heater substrate is arranged only on one side of the solid electrolyte substrate, the temperature difference between both sides of the solid electrolyte substrate was about 40 ° C. to 50 ° C., which was greatly improved.

  Further, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate 110 (the temperature detected by the thermocouple for temperature measurement attached to the central portion of the surface of the ceramic substrate facing the solid electrolyte substrate 110, and the solid electrolyte) The difference between the detected temperature (control temperature) of the thermocouple for temperature control attached to the end of the substrate 110 was about 5 ° C to 10 ° C. In the solid electrolyte type gas sensor of Conventional Example 2, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate was about 30 ° C., which was greatly improved.

  In the sensor block using the heating element 301 according to the sixth embodiment, it is possible to keep the temperature variation of almost the entire region of the electrode film formed on the solid electrolyte substrate within 5 ° C. The heating temperature of the solid electrolyte substrate 110 can be lowered. Therefore, it is possible to realize a gas sensor and a gas concentration measuring device that have a wide proton conduction area, high detection sensitivity, and can ensure long-term stability of measurement values.

<< Embodiment 7 >>
A good heat conductive substrate according to the seventh embodiment of the present invention will be described with reference to FIG. FIG. 11 is a perspective view of a good heat conductive substrate according to the seventh embodiment of the present invention. The good heat conductive substrate 350 is composed of good heat conductive substrates 351 and 352. The size of the good heat conductive substrate 351 is 12 mm × 12 mm × 0.5 mm, and is made of aluminum nitride. The good heat conductive substrate 351 has an opening of 5 mm × 5 mm in the center. The good heat conductive substrate 352 is made of alumina having a purity of 96%, and has almost the same size as the opening portion of the good heat conductive substrate 351. The good thermal conductivity substrate 351 has a higher thermal conductivity than the good thermal conductivity substrate 352.

  Instead of the good heat conductive substrates 201a and 201b of the sensor block 104 (FIG. 6) of the third embodiment, a sensor block using the good heat conductive substrate 350 is created, and the solid electrolyte substrate 110 is the same as in the first embodiment. The temperature of the corner portion was controlled at 350 ° C. to measure the temperature. As a result, the temperature difference between the central portions of the ceramic substrates 113a and 113b on the electrode film side was within 2 ° C. to 3 ° C. (slightly larger than Embodiment 3). In the sensor part of Conventional Example 1 in which the heater substrate is arranged only on one side of the solid electrolyte substrate, the temperature difference between both sides of the solid electrolyte substrate was about 40 ° C. to 50 ° C., which was greatly improved.

  Further, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate 110 (the temperature detected by the thermocouple for temperature measurement attached to the central portion of the surface of the ceramic substrate facing the solid electrolyte substrate 110, and the solid electrolyte) The difference between the temperature control thermocouple attached to the end of the substrate 110 (the difference from the detected temperature (control temperature)) was about 10 ° C. although it varied slightly. Compared with the solid electrolyte type gas sensor of Conventional Example 2, the temperature difference between the central portion and the end portion in the same plane of the solid electrolyte substrate was about 30 ° C., which was improved.

  In the sensor block using the highly heat conductive substrate 350 according to the seventh embodiment, it is possible to reduce the temperature variation in almost the entire region of the electrode film formed on the solid electrolyte substrate as compared with the conventional case. The heating temperature of the solid electrolyte substrate can be lowered. Therefore, it is possible to realize a gas sensor and a gas concentration measuring device that have a wide proton conduction area, high detection sensitivity, and can ensure long-term stability of measurement values.

<< Embodiment 8 >>
A gas sensor structure and a gas concentration measurement device (a hydrogen gas concentration measurement device) according to an eighth embodiment of the present invention will be described with reference to FIGS.
FIG. 12 is a block diagram showing the configuration of the gas concentration measuring apparatus according to the eighth embodiment of the present invention. The gas concentration measuring device 109 includes a sensor structure 108, a temperature control unit 121, a voltage control unit 122, a current detection unit 123, and a gas concentration calculation unit 124. The sensor structure 108 includes a sensor module 107.

  FIG. 13 is a cross-sectional view of the sensor module according to the eighth embodiment of the present invention. The sensor module 107 has a configuration in which the sensor block 104 (the sensor block according to the third embodiment, see FIG. 6) is covered with heat insulating materials 411 to 417. The heat insulating materials 411 to 417 are formed from mica materials. A gas inlet / outlet port 421 is formed on the gas diffusion rate controlling hole 114 and the gas flow hole 115 side of the sensor block 104.

  The sensor module 107 is attached to the sensor attachment member 513 of the sensor structure 108. FIG. 14 is a cross-sectional view of a sensor module mounting member according to Embodiment 8 of the present invention. The sensor mounting member 513 is made of machinable ceramics (Morcol manufactured by Corning). The sensor attachment member 513 has a plurality of screw holes 514 at the tip.

  In the periphery of the sensor module 107, the same number of openings as the screw holes 514 are provided. The sensor module 107 is fixed to the sensor mounting member 513 by a sensor module support 519 inserted in the opening. Specifically, first, the sensor module support 519 is fixed to the screw hole 514 of the sensor attachment member 513 with the screw 520, and then the sensor module 107 is fitted into the sensor module support 519. Finally, the heat-resistant spring 515 is fitted to the tip of the sensor module support 519 (the end opposite to the screw 520), and the E-ring 516 is compressed in the groove at the tip of the sensor module support 519 with the heat-resistant spring 515 compressed. Insert into. In this way, the sensor module 107 was fixed to the sensor attachment member 513. A gap forming portion 512 that is thicker than the other portions and larger in diameter than the peripheral opening portion of the sensor module 107 is formed on the upper portion of the screw 520 of the sensor module support 519. A predetermined distance is maintained between the member 513 and the member 513. With this configuration, heat generated from the sensor module 107 is not easily transmitted to the sensor mounting member 513.

  Reference numeral 517 denotes an explosion-proof cap that covers the entire sensor module 107 and the sensor module support 519. The explosion-proof cap 517 is formed of a porous material (SUS fine powder) obtained by sintering fine metal powder. The explosion-proof cap 517 has a function of mitigating fluctuations in measured values due to fluctuations in the measurement gas flow rate, a function of protecting the sensor unit, and an explosion-proof function. The measurement gas passes through the explosion-proof cap 517.

  Reference numeral 518 denotes a ceramic heat-resistant insulating tube having a plurality of through holes. The heater substrates 171a and 171b derived from the sensor module 107, the temperature control thermocouple (not shown) of the solid electrolyte substrate 110, and the anode electrode film 112 and the cathode electrode film 111 of the solid electrolyte substrate 110 are connected to the respective through holes. Inserted lead wires are respectively inserted. The heat resistant insulating tube 518 protects each lead wire and insulates between the lead wires. These lead wires are collectively referred to as “lead wire 692”.

  FIG. 15 is a sectional view of the entire gas sensor structure according to the eighth embodiment of the present invention. Reference numeral 621 denotes a metal base member to which the sensor attachment member 513 is attached. The metal base member 621 is fitted into the cap 622. The cap 622 is fitted into the lead wire protection cap 624. The entire sensor structure 108 is screwed to the through hole of the measurement unit outer wall 652.

  The lead wire 692 connected to the sensor module is inserted into the heat resistant insulating tube 518, further inserted into the insulating tube 654, and connected to the electrode pin 651. The external lead wire 693 and the electrode pin 651 in the cable 694 are crimped and connected at the overlapping sleeve press contact portion 655.

  An O-ring 671 is inserted between the metal base member 621 and the measurement unit outer wall 652. Electrode pins 651 are attached to the hermetic terminal plate 623 via O-rings 673. The hermetic terminal plate 623 is attached to the tip of the metal base member 621 via an O-ring 672. O-rings 671, 672, and 673 are configured to be tightened at a portion where the gas inside the measurement unit outer wall 652 of the sensor structure 108 contacts the air outside. Accordingly, the airtightness between the inside and outside of the sensor structure 108 is maintained. Therefore, the sensor structure 108 is a sensor structure of a gas concentration measuring device for combustible gas (for example, propane gas or natural gas), explosive gas (for example, hydrogen gas) or toxic gas (for example, carbon monoxide gas). It is effective as a body. The O-ring 671 may be removed, the metal base member 621 may be attached to the measurement unit outer wall 652 with a taper screw, and a gas seal tape made of Teflon (registered trademark) may be wound around the connection portion to perform gas sealing.

Returning to FIG. The temperature control unit 121 inputs an output signal of a temperature control thermocouple attached to the solid electrolyte substrate 110, adjusts the current flowing to the heating elements 172a and 172b, and sets the temperature of the solid electrolyte substrate 110 to a predetermined value (for example, 350 ° C.). ) To control. The voltage control unit 122 applies a predetermined voltage between the anode electrode film 112 and the cathode electrode film 111. The current detection unit 123 detects a current flowing between the anode electrode film 112 and the cathode electrode film 111. The gas concentration calculation unit calculates the gas concentration of the measurement gas based on the current detected by the current detection unit 123.
The gas concentration measuring device may display the value of the gas concentration on the display, or if the gas concentration exceeds a predetermined threshold value, it may turn on a warning lamp and sound a warning buzzer. Further, the gas concentration measuring device may send information on the gas concentration and / or information that the gas concentration has exceeded a predetermined threshold to a host device (for example, a computer) by wired or wireless communication.

  In place of the sensor block 104, the sensor block described in the first to seventh embodiments may be used.

  Although forsterite substrates are used as the ceramic substrates 113a, 113b, 153a, and 153b, any material that has heat resistance and a thermal expansion coefficient within ± 20% of that of the solid electrolyte substrate may be used. Although a mica plate is used for the heater substrates 171a and 171b, any material having heat resistance and electrical insulation may be used.

  The solid electrolyte gas sensor according to the embodiment of the present invention is a hydrogen gas sensor. The present invention is not limited to this, but by adjusting the size of the solid electrolyte material or the gas diffusion rate controlling hole, it can also be applied to other gases (for example, oxygen gas, hydrocarbon gas) that can be detected by the solid electrolyte, or sensors such as humidity. Applicable. For example, in the case of an oxygen gas sensor, the anode electrode film 112 in the embodiment functions as a cathode electrode film, and the cathode electrode film 111 functions as an anode electrode film.

  According to the present invention, since both surfaces of the solid electrolyte substrate can be uniformly heated and controlled, it is possible to realize a solid electrolyte gas sensor and a gas concentration measuring apparatus capable of continuously measuring gas concentration stably. The solid electrolyte type gas sensor and gas concentration measuring apparatus of the present invention are useful for continuous measurement of gas concentration in a continuous gas flow rate.

  Hydrogen gas sensor and hydrogen gas concentration measuring device that can continuously measure the hydrogen concentration in the reducing gas when the solid electrolyte substrate is made of perovskite ceramics with barium, zirconium, cerium, indium oxide ion conductivity Can be realized. Such a hydrogen gas sensor uses a measured value of the hydrogen gas concentration in the natural gas to calculate the total combustion calorie in a power generation system that needs to burn natural gas with a constant combustion calorie. It is useful as a gas sensor for automatic control. This is also an effective means for continuous measurement of the hydrogen gas concentration in the fuel cell gas.

  According to the present invention, the temperature difference between the central portion and the peripheral portion of the solid electrolyte substrate can be controlled to be small. That is, most of the anode electrode and cathode electrode can contribute to proton conduction. Therefore, it is possible to realize a solid electrolyte type gas sensor and a gas concentration measuring device with high sensitivity, a wide gas concentration detection range, and a relatively low heating temperature of the solid electrolyte substrate.

  The solid electrolyte type gas sensor and gas concentration measuring device of the present invention are useful as a solid electrolyte type gas sensor and gas concentration measuring device of a system that needs to perform highly accurate gas concentration measurement, for example.

Sectional drawing of the sensor part of Embodiment 1 of this invention The perspective view of the sensor part of Embodiment 1 of this invention 1 is an exploded perspective view of a sensor unit according to Embodiment 1 of the present invention. Sectional drawing of the sensor block of Embodiment 1 of this invention Sectional drawing of the sensor part of Embodiment 2 of this invention Sectional drawing of the sensor block of Embodiment 3 of this invention The exploded perspective view of the sensor block of Embodiment 3 of the present invention Sectional drawing of the sensor block of Embodiment 4 of this invention Sectional drawing of the sensor block of Embodiment 5 of this invention The perspective view of the heat generating body of Embodiment 6 of this invention. The perspective view of the good heat conductive board | substrate of Embodiment 7 of this invention. The block diagram which shows the structure of the gas concentration measuring apparatus of Embodiment 8 of this invention. Sectional drawing of the sensor module of Embodiment 8 of this invention Sectional drawing of the sensor module attachment member of Embodiment 8 of this invention Sectional drawing of the whole sensor structure of Embodiment 8 of this invention Sectional drawing of the sensor part of the sensor structure of the hydrocarbon sensor of Conventional Example 1 Exploded perspective view of sensor structure of Conventional Example 1 Sectional drawing of the gas sensor element of the solid electrolyte type gas sensor of the prior art example 2 Arrhenius plot of conductivity of stabilized zirconia

Explanation of symbols

DESCRIPTION OF SYMBOLS 101,102 Sensor part 103,104,105,106 Sensor block 107 Sensor module 108 Sensor structure 109 Gas concentration measuring apparatus 110 Solid electrolyte substrate 111 Cathode electrode film 112 Anode electrode film 113a, 113b, 153a, 153b Ceramic substrate 114, 156 Gas diffusion rate controlling hole 115, 157 Gas flow hole 116, 117, 154, 155 Adhesive 118, 119 Electrode terminal part 121 Temperature control part 122 Voltage control part 123 Current detection part 124 Gas concentration calculation part 171a, 171b Heater substrate 172a, 172b , 301 Heating elements 201a, 201b, 350, 351, 352 Good thermal conductive substrates 251, 264 Good thermal conductive substrates in vertical communication 303, 304, 305 Spacing 306, 307 Terminals 411 412, 413, 414, 415, 416, 417 Heat insulating material 421 Gas inlet / outlet 512 Interval forming portion 513 Sensor mounting member 514 Screw hole 515 Heat resistant spring 516 E-ring 517 Explosion-proof cap 518 Heat resistant insulating tube 519 Sensor module support 520 Screw 621 Metal base member 622 Cap 623 Airtight terminal plate 624 Lead wire protection cap 651 Electrode pin 652 Measurement unit outer wall 654 Insulating tube 655 Overlay sleeve pressure contact portion 671, 672, 673 O-ring 692 Lead wire 693 External lead wire 694 Cable 711 Solid Electrolyte substrate 712 Ceramic substrate 713 Auxiliary substrate 714 Heating element 721 Anode electrode film 722 Cathode electrode film 723, 724 Inorganic adhesive 725 Gas diffusion rate limiting hole 726 Ano Electrode chamber 751 Sensor portion 752 Flat portion 753 Ceramic cylinder 754 Lead wire 755 Metal lid 761 Metal case 762 Metal can 763 Vent hole 765 External lead wire 811 Solid electrolyte 812 Detection electrode 813 Reference electrode 814 Panel type Heater 821 Heating element 822 Current collecting electrode 823 Heater lead wire 824 Lead wire

Claims (20)

A solid electrolyte substrate having a pair of electrode films formed on both sides;
A gas diffusion rate-limiting part forming substrate that forms a gas diffusion rate-limiting hole, at least a part of which is bonded directly to the first surface of the solid electrolyte substrate or via another member disposed on the outer periphery of the electrode film;
A gas flow-portion forming substrate that forms a gas flow hole, at least a part of which is bonded to the second surface of the solid electrolyte substrate directly or via another member disposed on the outer periphery of the electrode film. ,
A limiting current type solid electrolyte gas sensor, wherein the gas diffusion rate controlling part forming substrate and the gas flow part forming substrate are a ceramic substrate or a porous substrate. The gas diffusion rate controlling part forming substrate and the gas flow part forming substrate are formed of the same material, and the thermal expansion coefficient of the material is within ± 20% of the thermal expansion coefficient of the solid electrolyte substrate. Item 2. The solid electrolyte type gas sensor according to Item 1. The planar heater substrate is disposed in close contact with the surfaces of the gas diffusion rate controlling portion forming substrate and the gas flow portion forming substrate that do not face the solid electrolyte substrate, respectively. The solid electrolyte type gas sensor according to claim 2. A first heat-conductive substrate disposed in close contact with the upper and lower substrates between the gas diffusion rate controlling portion forming substrate and the heater substrate; and between the gas flow portion forming substrate and the heater substrate. And a second good heat conductive substrate disposed in close contact with the upper and lower substrates,
4. The solid electrolyte according to claim 3, wherein the thermal conductivity of the first and second good thermal conductive substrates is larger than the thermal conductivity of the gas diffusion rate-limiting part forming substrate and the gas flow part forming substrate. Type gas sensor. The size of the heater substrate and / or the size of the first and second good thermal conductive substrates are larger than the solid electrolyte substrate, the gas diffusion rate controlling portion forming substrate, and the gas flow portion forming substrate. The solid oxide gas sensor according to claim 3 or 4, characterized in that it is characterized in that: The solid oxide gas sensor according to any one of claims 3 to 5, wherein the heater substrate is made of a highly heat conductive material. 7. The solid electrolyte type gas according to claim 4, wherein the first and second good thermal conductivity substrates have a thermal conductivity of 20 W / m · K or more. sensor. The first and second heat-conductive substrates are formed of alumina or ceramics mainly composed of alumina, beryllia ceramics, aluminum nitride ceramics, silicon carbide ceramics, aluminum, copper, or high-quality graphite sheets. The solid electrolyte gas sensor according to any one of claims 4 to 7, wherein the solid electrolyte gas sensor is characterized in that: A planar heater substrate is provided by arranging a third good thermal conductive substrate in close communication with each surface of the gas diffusion rate controlling portion forming substrate and the gas flow portion forming substrate on the side not facing the solid electrolyte substrate. 2. The solid oxide gas sensor according to claim 1, wherein the solid electrolyte gas sensor is disposed in close contact with a surface parallel to the first surface or the second surface outside the third highly heat conductive substrate. . A first good thermal conductive substrate disposed in close contact with a surface of the gas diffusion rate limiting portion forming substrate that is not opposed to the solid electrolyte substrate;
A second heat-conductive substrate disposed in close contact with the surface of the gas flow part forming substrate that is not opposed to the solid electrolyte substrate;
The surface of the first good heat conductive substrate on the side not facing the gas diffusion rate limiting portion forming substrate and the surface of the second good heat conductive substrate on the side not facing the gas flow portion forming substrate. A third good thermal conductive substrate in close communication with each other;
A planar heater substrate disposed in close contact with the first surface or the surface parallel to the second surface outside the third good thermal conductivity substrate;
Further comprising
The thermal conductivity of the first good thermal conductivity substrate, the second good thermal conductivity substrate, and the third good thermal conductivity substrate is the thermal conductivity of the gas diffusion rate controlling portion forming substrate and the gas flow portion forming substrate. The solid oxide gas sensor according to claim 1, wherein the gas sensor is larger. The size of each surface parallel to the first surface and the second surface of the third heat-conductive substrate and the size of the heater substrate, or the first surface of the third heat-conductive substrate. The size of the surface and each surface parallel to the second surface, the heater substrate, the first good thermal conductivity substrate, and the second good thermal conductivity substrate are determined by the solid electrolyte substrate, the gas diffusion rate limiting rate. The solid electrolyte type gas sensor according to claim 9 or 10, wherein the solid electrolyte type gas sensor is larger than the part forming substrate and the gas flow part forming substrate. The solid electrolyte substrate according to any one of claims 1 to 5 and claims 9 to 11, wherein the solid electrolyte substrate is formed of a barium / cerium / zirconium / indium oxide. Electrolytic gas sensor. An anode electrode is formed on one surface of a solid electrolyte substrate made of a ceramic material of proton and oxide ion conductors with barium, cerium, zirconium, and indium oxides, and a cathode electrode is formed on the other surface, respectively.
A porous substrate or a ceramic substrate is joined so as to cover the anode electrode so that a gas diffusion rate controlling hole is formed or formed,
A porous substrate or a ceramic substrate is bonded so as to cover the other cathode electrode so that a gas flow hole is formed or formed,
A good heat conductive substrate having a size larger than the porous substrate or the ceramic substrate is disposed on the outer surface of the both porous substrates or the ceramic substrate,
A solid oxide hydrogen gas sensor, wherein planar heaters having the same size as or larger than the good heat conductive substrate are disposed on both outer side surfaces of the good heat conductive substrate. The heating element is arranged on the surface of the heater substrate so that the surface temperature is higher in the peripheral portion than in the central portion, and any one of claims 3-6, 9-11 and 13 A solid electrolyte gas sensor according to 1. The first and second good thermal conductive substrates are each composed of a first substrate and a second substrate, the first substrate has a through hole in the center, and the second substrate is 14. The device according to claim 4, wherein the first substrate is fitted into a through hole, and the thermal conductivity of the first substrate is larger than the thermal conductivity of the second substrate. The solid electrolyte gas sensor described. The solid according to any one of claims 3 to 5, 9 to 11 and 13, wherein the whole is covered with a heat insulating material having an opening portion communicating with the gas diffusion rate controlling hole and the gas flow hole. Electrolytic gas sensor. The solid electrolyte gas sensor according to any one of claims 1 to 5, 9 to 11 and 13, wherein a cross-sectional area of the gas flow hole is larger than that of the gas diffusion rate controlling hole. A solid oxide gas sensor according to any one of claims 1 to 17,
A sensor mounting member that holds the solid electrolyte gas sensor and is formed of a ceramic material and has a cylindrical shape;
A metal explosion-proof member covering the entire solid oxide gas sensor;
A metal base member made of stainless steel having a cylindrical shape, attached to one end of the sensor attachment member,
An airtight terminal plate attached with a cap to the other end of the metal base member and having electrode pins;
Have
A lead wire connected to the solid oxide gas sensor is connected to one end of the electrode pin through an internal cavity of the sensor mounting member and the metal base member;
An external lead wire is connected to the other end of the electrode pin,
A structure in which the outer peripheral portion of the metal base member and the mounting surface of the gas concentration detection device, the metal base member and the airtight terminal plate portion, and the airtight terminal plate and the electrode pin insertion portion are connected in an airtight state, respectively. Solid electrolyte type gas sensor structure characterized by the above. 19. The solid oxide gas sensor structure according to claim 18, wherein the solid electrolyte gas sensor is attached to a sensor attachment member with a gap therebetween. A solid oxide gas sensor according to any one of claims 1 to 17, and
A temperature control unit for heating the solid electrolyte substrate and controlling it to a predetermined temperature;
A voltage controller that applies a predetermined voltage between the pair of electrode films;
A current detection unit for detecting a current flowing between the pair of electrode films;
A gas concentration calculation unit for calculating a gas concentration from at least the current detected by the current detection unit;
A gas concentration measuring device comprising:

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