Proton conductor gas sensor

Abstract

In a proton conductor gas sensor, an MEA having a proton conductor film is placed on the bottom of a metal can, a sealing body is arranged on the upper portion of the MEA, and a gasket is used to seal between the side peripheral portion of the metal can and the sealing body. The gasket is made of synthetic resin, and a synthetic rubber member that is easily deformed compared to the gasket is arranged airtightly between the bottom of the gasket and the bottom of the metal can. The effect is that the impact resistance of the proton conductor gas sensor is improved.

Description

Technical Field

[0001] This invention relates to proton-conducting gas sensors, and particularly to improvements in the shock resistance of gas sensors. Background Technology

[0002] Patent document 1 (JP2011-220905A) discloses a proton-conducting gas sensor. In this gas sensor, a membrane electrode assembly (MEA) is used, consisting of a proton-conducting membrane, a pair of electrodes (detector and counter electrode), and a pair of gas diffusion membranes. The MEA is housed at the bottom of a metal can, and a metal sealing body containing a filter such as activated carbon is disposed on top of the MEA. An annular gasket is disposed between the sealing body and the metal can, and the gasket is compressed by riveting the metal can. This achieves the following effect.

[0003] • Position the seal and MEA using pressure from the gasket.

[0004] • Insulate the sealing body from the metal can.

[0005] • Seal the gap between the sealing body and the metal can. It should be noted that Patent Document 1 proposes a polyolefin-based elastomer as the material for the gasket.

[0006] In the gas sensor described in Patent Document 1, a metal canister is connected to the counter electrode of the MEA, and a sealing body is connected to the detection electrode of the MEA. The current between the two electrodes is proportional to the amount of gas reaching the MEA and decomposing at the detection electrode. Therefore, a sensor signal proportional to the gas concentration is obtained. Such a gas sensor is used for the detection of CO, H2, ethanol, acetone, etc.

[0007] Existing technical documents Patent documents Patent Document 1: JP2011-220905A Summary of the Invention

[0008] The problem that the invention aims to solve The inventor subjected a gas sensor similar to that in Patent Document 1 to an impact resistance test. As a result, the gas sensitivity increased. The mechanism for this increased gas sensitivity is as follows: Due to the impact applied during the impact test, the seal between the gasket and the metal canister becomes incomplete. Therefore, a path for gas from the external gas to diffuse towards the detection electrode is created through the gap between the metal canister and the gasket, resulting in increased gas sensitivity.

[0009] The objective of this invention is to improve the shock resistance of proton-conducting gas sensors.

[0010] Methods for solving problems The proton-conducting gas sensor of the present invention comprises: A metal can with a flat bottom and annular sides; MEA (membrane electrode complex) has a proton-conducting membrane placed at the bottom of a metal can. The sealing body, viewed from the MEA, is located on the opposite side of the metal can. It is made of metal and houses the filter in the internal space. It has a first opening for supplying external gas to the internal space and a second opening for supplying external gas treated by the filter to the MEA from the internal space. And annular gaskets, positioned between the side periphery of the metal can and the sealing body. The end of the metal can's side circumference, opposite to the bottom of the metal can, bends towards the sealing body to pressurize the gasket.

[0011] Furthermore, the gasket is made of synthetic resin. In addition, a ring-shaped synthetic rubber component, which is more prone to deformation under pressure than the gasket and has a lower hardness, is airtightly arranged between the bottom of the gasket and the bottom of the metal can, surrounding the MEA.

[0012] When an impact is applied to a proton-conducting gas sensor, the gas sensitivity sometimes increases (see [reference to existing examples of proton-conducting gas sensors]). Figure 9 ).exist Figure 9 The increase in gas sensitivity was approximately twofold. This is believed to be due to the loosening of the airtight seal between the gasket and the bottom of the metal can due to the impact, creating a venting path from the side periphery of the gasket and the bottom of the metal can. It is thought that external gas reaching the MEA from the surrounding area via this venting path diffuses from the top of the MEA into the MEA, thus increasing gas sensitivity.

[0013] In contrast, in this invention, a ring-shaped synthetic rubber component, which is more easily deformed by pressure than the gasket, is disposed between the bottom of the gasket and the bottom of the metal can. This ensures that the gap between the rubber component and the bottom of the metal can remains airtight, preventing unwanted external gas from diffusing into the MEA (see the example of the proton conduction gas sensor for details). Figure 8 As a result, the impact resistance of the proton-conducting gas sensor can be improved in this invention. A representative example of impact is drop impact; in this invention, the increase in gas sensitivity caused by drop impact testing can be reduced by the synthetic rubber component.

[0014] Preferably, a bottom plate made of metal with a wall thickness thicker than the metal can and a circular plate shape is placed on the bottom of the metal can, and the MEA and synthetic rubber components are disposed on the bottom plate. The bottom plate is less prone to deformation due to impact than the bottom of the metal can, thus reducing the likelihood of gaps forming between the synthetic rubber components and the bottom plate.

[0015] The preferred material for gaskets is at least one of high-density polyethylene, nylon, and PTFE (polytetrafluoroethylene). Additionally, the preferred material for synthetic rubber components is at least one of NBR rubber (acrylonitrile and butadiene rubber), silicone rubber, FKM, PTFE rubber (polytetrafluoroethylene rubber), and nitrile rubber. FKM is a fluoroelastomer, sold under trade names such as Viton (Viton is a registered trademark of Chemours). PTFE rubber has a lower hardness than the PTFE used in gaskets and is sold under trade names such as Teflon rubber (TEFLON is a registered trademark of DuPont).

[0016] Assuming the gasket is made of the same material as the synthetic rubber components, even if the metal cans are riveted together, sufficient pressure cannot be applied from the gasket to the seal and MEA, making it impossible to position them. Therefore, the deviation in gas sensitivity increases, and the gas sensitivity becomes susceptible to fluctuations due to impacts, etc.

[0017] Synthetic rubber components can be any ring shape, and the shape is not limited to sheet form. However, if the synthetic rubber component is made into an O-ring of synthetic rubber, the manufacture or acquisition of the synthetic rubber component becomes easier.

[0018] As a proton-conducting gas sensor, a diffusion control plate is disposed between the MEA and the sealing body, and has a diffusion control port for supplying external gas from a second opening in the sealing body to the MEA. The diameter of the diffusion control port is smaller than the diameter of the second opening. It is easier to set a correctly sized opening in the diffusion control plate than in the sealing body, thus enabling more accurate control of the amount of external gas supplied to the MEA.

[0019] In this type of proton-conducting gas sensor, the diffusion control plate is pressurized towards the MEA near the diffusion control port. Therefore, MEA material can intrude into the diffusion control port, sometimes causing changes in gas permeability. This results in a deviation in gas sensitivity. Therefore, it is preferable to provide a protrusion on the diffusion control plate that extends from the diffusion control port towards the opposite side (filter side) of the MEA, with a gap between the protrusion and the MEA. This prevents MEA material from intruding into the diffusion control port, keeps the supply of external gas to the MEA constant, and further reduces variations in gas sensitivity.

[0020] The gas flow path between the gasket and the inner circumference of the metal can is sealed by an annular synthetic rubber component. The inventors investigated whether other undesirable gas flow paths existed. They discovered a tiny gas flow path between the bottom surface of the sealing body and the top surface of the diffusion control plate, through which gas could move from the opening of the sealing body towards the MEA. Both the sealing body and the diffusion control plate are made of metal with finely textured surfaces, thus creating such a flow path. Gas moving to the end of the diffusion control plate can reach the MEA through the gap between the MEA and the synthetic rubber component.

[0021] To cut off this flow path, simply extend the outer peripheral end of the diffusion control plate to the position between the gasket and the synthetic rubber component. As a result, the gap between the MEA and the synthetic rubber is covered by the diffusion control plate, and the flow path is blocked.

[0022] As the gas moves along the top surface of the diffusion control plate to its outer periphery, the interface between the synthetic rubber component and the metal can, or the interface between the diffusion control plate and the synthetic rubber component, can then become a gas flow path. However, the synthetic rubber component is compressed due to the pressure during riveting and is in close contact with the bottom of the metal can and also with the bottom of the diffusion control plate, making it difficult for the gas to pass through their interface. Preferably, the outer periphery of the diffusion control plate is positioned between the gasket and the synthetic rubber component throughout its entire circumference.

[0023] Alternatively, instead of extending the diffusion control plate towards the inner circumference of the metal can, an airtight membrane of conductive material can be placed between the diffusion control plate and the bottom surface of the sealing body. This membrane airtightly seals the interface between the diffusion control plate and the sealing body, and because it is conductive, it electrically connects the diffusion control plate and the sealing body. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of the proton-conducting gas sensor in the basic embodiment.

[0025] Figure 2 yes Figure 1 Enlarged cross-sectional view of the main parts of a proton-conducting gas sensor.

[0026] Figure 3 This is a plan view of the gasket used in the embodiment.

[0027] Figure 4 This is a plan view of the O-ring used in the embodiment.

[0028] Figure 5 This is a cross-sectional view of the O-ring used in the embodiment.

[0029] Figure 6 This is a cross-sectional view of the O-ring used in the modified example.

[0030] Figure 7 This is a flowchart illustrating the durability test, including the drop impact test, in the embodiments.

[0031] Figure 8 This indicates the results of the durability tests in the embodiments.

[0032] Figure 9 This indicates the results of a durability test on a conventional proton-conducting gas sensor.

[0033] Figure 10 This is a cross-sectional view of the proton-conducting gas sensor in the second embodiment.

[0034] Figure 11 This is an enlarged cross-sectional view of the main parts of the diffusion control plate and MEA in the second embodiment.

[0035] Figure 12 This is an enlarged cross-sectional view of the main parts of the diffusion control board and MEA in the basic embodiment.

[0036] Figure 13 This is a characteristic graph showing the distribution of the initial values ​​of CO sensitivity in the second embodiment and the basic embodiment.

[0037] Figure 14 This is a cross-sectional view of the proton-conducting gas sensor in the preferred embodiment.

[0038] Figure 15 This is a cross-sectional view of the gas sensor of the preferred embodiment, parallel to the base plate.

[0039] Figure 16 This is a cross-sectional view of a modified example of the diffusion control plate with a different construction from the preferred embodiment.

[0040] Figure 17 This is a cross-sectional view of a second variant of the preferred embodiment, which alters the construction of the diffusion control plate.

[0041] Figure 18 This is a cross-sectional view of a third variation of the diffusion control plate, which differs from the preferred embodiment.

[0042] Figure 19 This is a characteristic graph representing the distribution of CO sensitivity after the drop test in the second embodiment.

[0043] Figure 20 This is a characteristic graph representing the distribution of CO sensitivity after the drop test in the preferred embodiment.

[0044] Symbol Explanation 2. Proton Conductor Gas Sensor 4. Metal cans 5. Bottom 6. Base plate 7. Lateral area 8. Riveted parts 9. Sealing body 10 (for external gas introduction) opening 11 (Opening for external gas supply) 12 Filters 14 MEA 15 Proton Conductor Film 16 detection poles 17 pairs of electrodes 18, 19 Gas diffusion membranes 20 Diffusion Control Panel 21 Diffusion control aperture 22 gaskets 23 protuberance 24 Bottom 26, 30 O-rings 32 flange 36 Proton Conductor Gas Sensor 40 Diffusion Control Panel 41. Protrusion 42 Diffusion control port 43 gap 46. ​​A composite of a proton-conducting membrane and a pair of electrodes 50, 60, 70, 80 Diffusion Control Plates 50b, 60b, 70b extension 50C insulating film 52, 62, 72, 82 Proton Conductor Gas Sensors 54 gap 70d peripheral end 74 Insulating film 80b conductive material film Detailed Implementation

[0045] The following are examples of embodiments for implementing the present invention.

[0046] [Example] Construction of gas sensors Figures 1-8 The figures illustrate a basic embodiment. In each figure, the proton-conducting gas sensor 2 includes a circular metal can 4 in plan view, a flat bottom 5, and a metal base plate 6 mounted on the bottom. The wall thickness of the base plate 6 is greater than the wall thickness of the bottom 5, and the rigidity of the base plate 6 is higher than that of the bottom 5. A side peripheral portion 7 is a circular portion of the metal can 4 in plan view, and a riveted portion 8 is a riveted portion on the upper part of the side peripheral portion 7.

[0047] The sealing body 9 is a sealing body with two circular metal plates welded together. The filter 12 is housed within its internal space, removing unwanted gases through adsorption or reaction. Openings 10 are located at the external gas inlet, the top or side of the sealing body 9, etc., while opening 11 is located at the external gas supply opening at the bottom of the sealing body 9. External gas passing through the filter 12 is supplied to the MEA 14 via the diffusion control plate 20. The diffusion control plate 20 is a thin metal plate that supplies external gas to the MEA 14 through the diffusion control hole 21.

[0048] MEA14 has a proton-conducting film 15 at its center in the thickness direction. Figure 1 , Figure 2 The membrane 15 has a detection electrode 16 on the upper side and a counter electrode 17 on the lower side. Furthermore, a gas diffusion membrane 18 made of activated carbon, carbon sheet, or similar material is provided on the upper side of the detection electrode 16, and a gas diffusion membrane 19 made of the same material is provided on the lower side of the counter electrode 17.

[0049] Regarding gasket 22 and O-ring 26, O-ring 26 is configured to substantially surround MEA14, and gasket 22 is configured to substantially surround sealing body 9. Gasket 22 is shown in the plan view... Figure 3 As shown in the diagram, the upper outer periphery has a circular protrusion 23, and the bottom 24 is circular. The O-ring 26 is shown in the plan view as follows. Figure 4 The image shown is circular, with a cross-sectional shape as follows: Figure 5 The image shown is square. However, it can also be like... Figure 6 Like the O-ring 30, the cross-sectional shape is set to an elliptical or circular shape, which deviates from a circle.

[0050] If the metal can 4 is riveted using the riveted part 8, the gasket 22 is compressed and presses against the sealing body 9, allowing it to be positioned relative to MEA14. Furthermore, due to the pressure accompanying the riveting, the O-rings 26 and 30 are compressed and fill the gap between them and the base plate 6, preventing the creation of a gas passage between the O-rings 26 and 30 and the base plate 6. Therefore, the O-rings 26 and 30 are softer than the gasket 22. The O-rings 26 and 30 themselves are not critical; for example, they could be ring-shaped sheets or ring-shaped sheets with protrusions protruding towards the base plate 6. Alternatively, they could be a ring-shaped, soft rubber layer existing between the gasket 22 and the base plate 6. Furthermore, the gasket material is divided into upper and lower parts, and its dimensions are set to the combined dimensions of the gasket 22 and the O-rings 26. Soft rubber can be used in the area corresponding to the O-rings 26. In this specification, the elastomer is included within the rubber. Additionally, the ring-shaped component does not need to be physically separate from the gasket.

[0051] The gasket 22 is made of synthetic resin, such as preferably nylon 66, PTFE or other fluoropolymers, high-density polyethylene, etc. In this embodiment, the gasket 22 is made of high-density polyethylene. The O-rings 26 and 30 are preferably made of NBR rubber, silicone rubber, FKM, PTFE rubber, nitrile rubber, etc.

[0052] The Shore hardness D of gasket 22 is preferably 50 to 90, more preferably 55 to 90, and particularly preferably 60 to 90. The Shore hardness A of O-rings 26 and 30 is preferably 50 to 90, more preferably 50 to 85, and particularly preferably 50 to 80. Here, the material and hardness of O-rings 26 and 30 are shown, but the same applies to synthetic rubber parts of shapes other than O-rings. Shore hardness D is a unit expressing the hardness of plastics, etc., while Shore hardness A is a unit expressing the hardness of rubber, etc. Furthermore, 40 in Shore hardness D is approximately equivalent to 90 in Shore hardness A. Shore hardness is measured using a commercially available Shore hardness tester according to ASTM D2240.

[0053] Examples of the dimensions of the gasket 22, O-ring 26, etc., will be explained. The distance D from the bottom of the flange 32 protruding from the side of the sealing body 9 to the bottom plate 6 is 2 mm in this embodiment. The height H1 occupied by the inner gasket 22 is, for example, 0.8 to 1.5 mm, and the height H2 occupied by the O-ring 26 is 1.2 to 0.5 mm. Furthermore, the outer diameter of the gasket 22 and the O-ring 26 is, for example, 13 mm, and the inner diameter is, for example, 11 mm. Additionally, the thickness T of the bottom plate 6 is 0.5 to 0.7 mm, and the thickness of the metal can 4 is 0.2 mm.

[0054] In the assembly of the gas sensor 2, a base plate 6 is placed on the bottom 5 of the metal can 4, and an MEA 14 is placed on top of it. An O-ring 26 and a gasket 22 are arranged around the MEA 14. Then, a sealing body 9 is placed on top of the MEA 14 inside the gasket 22, and the riveted part 8 of the metal can 4 is riveted.

[0055] Gas sensor test Figure 7 The following describes the characteristic evaluation steps for gas sensor 2. The initial gas sensitivity (e.g., CO sensitivity) of the manufactured gas sensor 2 is measured (S1). Next, as a heat resistance test, it is placed in a 260°C bath for 50 seconds (S2). The gas sensitivity is measured after heating (S3). As a drop impact test, it is dropped 5 times from a height of 2.1m onto a concrete surface (S4), after which the gas sensitivity is measured (S5).

[0056] High-density polyethylene (Shore hardness D: 70) was used as gasket 22, and NBR rubber (Shore hardness A: 70) was used as O-ring 26. In the embodiment, tests were conducted on four gas sensors 2. Figure 8 As an example, tests were conducted using three gas sensors without O-rings 26 and with gaskets 22 occupying the positions of O-rings 26. Figure 9 ).

[0057] While all gas sensors exhibit sufficient heat resistance, in existing examples, the gas sensitivity increases by up to 2 times through drop tests. In this embodiment, the increase in gas sensitivity is less than 10%, which is sufficiently small compared to existing examples.

[0058] Second Embodiment Figures 10-13 This describes a second embodiment that reduces the sensitivity deviation caused by the material of MEA14 entering the diffusion control aperture 21. Except where specifically indicated, with... Figures 1-8 The basic embodiments are the same. In particular, the gasket 22 and O-ring 26 are the same as those described above. Figures 1-8 The basic embodiment is constructed in the same manner. Alternatively, O-ring 30 can be used instead of O-ring 26.

[0059] MEA14 is sometimes subjected to pressure from gasket 22 via sealing body 9, and the material of MEA14 enters... Figure 1 The diffusion control hole 21 is located within the diffusion control plate 40. Consequently, the gas sensitivity changes. Therefore, in the gas sensor 36 of the second embodiment, a protrusion 41 is provided in the diffusion control plate 40 at a position housed within the opening 11, and a diffusion control hole 42 is provided in the center of the protrusion 41. As a result, a gap 43 is created between the MEA 14 and the protrusion 41, preventing the MEA material from entering the diffusion control hole 42. Furthermore, Figure 14 46 is a composite of a proton conductor film and a pair of electrodes.

[0060] Examples of dimensions related to the diffusion control plate 40 are shown. The diameter of the opening 11 is, for example, 2.5 mm, and the outer diameter of the protrusion 41 is... For example, the diameter d of the diffusion control hole 42 is 0.1 mm, the height b of the protrusion 22 is 0.2 mm, and the thickness t of the diffusion control plate 40 is 0.1 mm.

[0061] Figure 13 This illustrates the effect of the second embodiment. The basic embodiment refers to... Figures 1-8 In this embodiment, the initial gas sensitivity deviation is larger compared to the second embodiment. Furthermore, the second embodiment differs from the second embodiment in that it uses an O-ring 26 to prevent unwanted intrusion of external gases. Figures 1-8 The embodiments are the same.

[0062] Best Practice Figures 14-18 This indicates the best embodiment and its variations. Figure 20 This indicates the deviation of CO sensitivity after the drop test in the best embodiment. Figure 19 This indicates a deviation from the second embodiment. The preferred embodiment, unless otherwise specifically indicated, is consistent with... Figure 10 , Figure 11 The second embodiment shown is the same. Additionally, in the preferred embodiment and its variations, a protrusion 41 is present in the center of the diffusion control plate, and a diffusion control port 42 is present on its top surface. However, it is also possible to... Figures 1-8 As in the embodiment, there is no protrusion 41. Additionally, except where specifically indicated, compared to... Figures 1-8 The description relating to the embodiments also applies to the preferred embodiments and their variations. For example, it is also possible not to use... Figure 5 The square O-ring 26, and using Figure 6 O-ring 30.

[0063] In various embodiments, an O-ring 26 is used to seal the flow path between the gasket 22 and the metal can 4. The inventors discovered that, as... Figure 14 As indicated by the middle arrow, a gas flow path may also exist between the bottom surface of the sealing body 9 and the top surface of the diffusion control plate 40. Both the sealing body 9 and the diffusion control plate 40 are made of metal, and their surfaces have fine irregularities that can serve as gas flow paths. Furthermore, in Figure 1 , Figure 10 In the gas sensor, gas passing through the interface between the sealing body 9 and the diffusion control plate 40 via the opening 11 of the sealing body 9 may pass through... Figure 14 The gap 54 reaches MEA14, causing a deviation in the sensor's gas sensitivity. Furthermore, the existence of such a gas flow path can... Figure 19 , Figure 20 To make a presumption.

[0064] To eliminate the influence of this gas flow path, the diffusion control plate 40 is extended to the upper part of the O-ring 26. Thus, as... Figure 10 As shown, gas will not escape from the gap between O-ring 26 and MEA14 ( Figure 14 (The portion indicated by symbol 54) diffuses. Additionally, in the preferred embodiment, it is not necessary to make the interface between the sealing body 9 and the diffusion control plate 40 airtight.

[0065] Figure 14 , Figure 15This diagram illustrates the construction of the proton-conducting gas sensor 52 and the diffusion control plate 50 in the preferred embodiment. The diffusion control plate 50 is circular, and its entire outer periphery is in contact with or located in front of the flange 32. Viewed from the diffusion control port 42, the outer periphery of the diffusion control plate 50 extends at least to the upper part of the O-ring 26, blocking the gap 54. Furthermore, the thickness of the riveted O-ring 26 is approximately equal to the thickness of the MEA 14. Within the diffusion control plate 50, the portion located above the O-ring 26 is referred to as the extension 50b. Figure 14 , Figure 15 In this process, the metal diffusion control plate 50 extends to the vicinity of the flange 32, and therefore an insulating film 50c is provided at the outer peripheral end of the diffusion control plate 50, i.e., the outer peripheral end of the extension 50b. Figure 14 The left side shows the insulating film 50c and its surroundings. Even if the extension 50b contacts the flange 32, the detection electrode and counter electrode of MEA14 will not be short-circuited due to the insulating film 50c.

[0066] Even if the gas passing through the opening 11 between the diffusion control plate 50 and the bottom surface of the sealing body 9 reaches the flange 32, it will not pass between the O-ring 26 and the base plate 6. Therefore, the gas does not reach MEA14. In addition, the spacer 22 and the extension 50b of the diffusion control plate 50 are also substantially airtight. Therefore, the influence of the flow path between the diffusion control plate 50 and the bottom surface of the sealing body 9 is minimal.

[0067] Figure 16 This illustrates a modified example where the outer periphery of the extension is confined to a position above the O-ring 26, which is closer to the flange 32. The proton-conducting gas sensor 62 is a new type of proton-conducting gas sensor where the diffusion control plate 60 and the extension 60b are not in contact with the flange 32.

[0068] Figure 17 The diagram shows the installation of an insulating film 74 instead of... Figure 14 A modified example of the insulating film 50c of 15. In this example, the proton-conducting gas sensor 72 is a proton-conducting gas sensor, the diffusion control plate 70 is a diffusion control plate, and the extension portion 70b is its extension portion. The annular insulating film 74 is fixed to the outer peripheral end 70d of the extension portion 72 by bonding or heat pressing. Furthermore, the outer peripheral end 70d of the extension portion 70b is located at a position that does not contact the inner periphery of the flange 32.

[0069] exist Figure 16 , Figure 17 The gas sensors 62 and 72 can also prevent gas from reaching MEA14 through the space between the diffusion control plates 60 and 70 and the sealing body 9.

[0070] exist Figure 18In the gas sensor 82, a conductive material film 80b is provided on the top surface of the diffusion control plate 80 on the sealing body 9 side. The film 80b is, for example, an In vapor-deposited film, a deposited film, or a foil, and can also be a film of other low-melting-point metals such as Ga alloys or Sn alloys. The melting point of In is preferably about 160°C, and the melting point of the low-melting-point metal is preferably 120°C or higher and less than 200°C. The film thickness is, for example, 1 μm or more and 10 μm or less, and is larger than the surface roughness of the diffusion control plate 80 and the sealing body 9.

[0071] The membrane 80b has a low melting point and is soft near room temperature, thus deforming under the pressure of riveting. As a result, the interface between the diffusion control plate 80 and the bottom surface of the sealing body 9 is filled with In, becoming airtight. In cases where the melting point is higher than In, for example, to avoid affecting the performance of the proton-conducting gas sensor, riveting can be performed at a temperature of 80–150°C. Alternatively, the membrane 80b can be disposed on the bottom surface of the sealing body 9 instead of on the diffusion control plate.

[0072] Alternatively, instead of forming film 80b from low-melting-point metals, metal powders such as silver and copper, or conductive carbon powders such as graphite and carbon black, can be mixed with resin binders and formed into film using 3D printing, spin coating, or printing. In this case, the plastically deformable film 80b deforms due to the pressure during riveting, filling the unevenness between the diffusion control plate 80 and the sealing body 9.

[0073] Figure 19 The second embodiment ( Figure 10 Changes in CO sensitivity caused by heat resistance and drop tests in the test. Figure 20 The preferred embodiment is indicated by ( Figure 14 The changes in 15) are as follows. The test procedure is the same as that shown in the test column of the gas sensor, and the number of samples is... Figure 19 There are 2 in the middle, in Figure 20 There are 3 in the middle. In the preferred embodiment, the change in sensitivity based on heat resistance and drop tests is smaller than in the second embodiment. This indicates that there is an unwanted gas flow path between the diffusion control plate and the bottom surface of the sealing body. Furthermore, due to heating and drop, the diffusion control plate and the sealing body undergo a slight positional shift, thus changing the permeability, which manifests as a change in gas sensitivity. In addition, in Figure 19 In (second embodiment), with Figure 8 Compared to the initial embodiment, the sensitivity of the heat resistance test changed significantly. However, the reason for this is unknown.

Claims

1. A proton-conducting gas sensor, characterized in that, have: A metal can with a flat bottom and annular sides; MEA, or membrane electrode complex, has a proton-conducting membrane placed at the bottom of a metal can. The sealing body, viewed from the MEA, is positioned on the opposite side of the metal can, is made of metal, and houses a filter within its internal space. It has a first opening for supplying external gas to the internal space and a second opening for supplying filtered external gas from the internal space to the MEA; and An annular gasket is positioned between the side periphery of the metal can and the sealing body. In a proton-conducting gas sensor, the end of the metal can's circumference opposite to the bottom of the can bends towards the sealing body to pressurize the gasket. The gasket is made of synthetic resin. Compared to the gasket, a ring-shaped synthetic rubber component that is easily deformed by pressure surrounds the MEA and is airtightly disposed between the bottom of the gasket and the bottom of the metal can.

2. The proton-conducting gas sensor according to claim 1, characterized in that, A metal base plate is placed at the bottom of the metal can. The wall thickness of this base plate is greater than the wall thickness of the metal can at the bottom, and this base plate is circular. The MEA and the synthetic rubber component are disposed on the base plate.

3. The proton-conducting gas sensor according to claim 1, characterized in that, The gasket is made of at least one of high-density polyethylene, nylon, and PTFE (polytetrafluoroethylene). The synthetic rubber component is composed of at least one of NBR rubber, silicone rubber, FKM, PTFE rubber, and nitrile rubber.

4. The proton-conducting gas sensor according to claim 3, characterized in that, The synthetic rubber component is an O-ring made of synthetic rubber.

5. The proton-conducting gas sensor according to claim 1, characterized in that, The synthetic rubber component reduces the increase in gas sensitivity caused by drop impact testing.

6. The proton-conducting gas sensor according to claim 1, characterized in that, A diffusion control plate is positioned between the MEA and the sealing body, and has a diffusion control port for supplying external gas from the second opening of the sealing body to the MEA. The diameter of the diffusion control port is smaller than the diameter of the second opening. The diffusion control plate has a protrusion extending from the diffusion control port to the side opposite to the MEA. There is a gap between the protrusion and the MEA.

7. The proton-conducting gas sensor according to claim 1, characterized in that, A diffusion control plate is disposed between the MEA and the sealing body, and has a diffusion control port for supplying external gas from the second opening of the sealing body to the MEA. The diameter of the diffusion control port is smaller than the diameter of the second opening. Furthermore, the outer peripheral end of the diffusion control plate is located between the gasket and the synthetic rubber component.

8. The proton-conducting gas sensor according to claim 7, characterized in that, The outer peripheral end of the diffusion control plate is located between the gasket and the synthetic rubber component over the entire circumference of the diffusion control plate.

9. The proton-conducting gas sensor according to claim 1, characterized in that, A diffusion control plate is disposed between the MEA and the sealing body, and has a diffusion control port for supplying external gas from the second opening of the sealing body to the MEA. The diameter of the diffusion control port is smaller than the diameter of the second opening. Furthermore, a film of conductive material is provided on the top surface of the diffusion control plate or the bottom surface of the sealing body to airtightly seal the interface between the diffusion control plate and the sealing body.

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