Seal material, observation window, and battery unit

Abstract

A seal material (100) comprises a seal material body (10) that fulfills a sealing function between members, and a detection unit (20) that changes color when in contact with a gas to be detected.

Description

Sealing material, sight glass, and battery unit

[0001] The present invention relates to a sealing material, an observation window, and a battery unit.

[0002] Secondary batteries used in electric vehicles and the like are capable of discharging by converting chemical energy from chemical reactions into electrical energy and charging by reverse reactions. Lithium secondary batteries, in particular, have high energy density and are used in a wide range of fields. Such secondary batteries are configured with a cell unit sealed within a housing that defines an enclosed space. Some secondary batteries generate hydrogen sulfide due to sulfide-based electrolyte materials, etc. Because the generation of hydrogen sulfide leads to battery degradation, techniques for electrically detecting hydrogen sulfide have been proposed (Patent Documents 1 and 2).

[0003] International Publication No. 2011 / 074097 Pamphlet Japanese Patent Application Laid-Open No. 2018-73801

[0004] However, the technologies described in Patent Documents 1 and 2 require electrical detection of hydrogen sulfide, resulting in a complex device configuration. Furthermore, because secondary batteries contain rare metals, it is preferable to reuse the battery itself or a portion of it. Therefore, it is anticipated that dealers or other personnel will dismantle and repair the battery. From a safety perspective, it is desirable to check the hydrogen sulfide generation status before disassembling the casing.

[0005] The present invention has been made in consideration of the above-mentioned problems, and provides a sealing material, a sight glass, and a battery unit that can detect the generation of gas (hydrogen sulfide, etc.) inside a housing without using electrical methods and before the housing is disassembled.

[0006] According to the present invention, there is provided a sealing material comprising a sealing material body that performs a sealing function between members, and a detection portion that changes color when it comes into contact with a gas to be detected.

[0007] Furthermore, according to the present invention, there is provided a peephole that is attached to an opening that penetrates the inside and outside of a housing that defines a closed space, and that allows the inside of the closed space to be viewed from outside the housing, the peephole comprising: a window member that is transparent to visible light; and a sealing material that seals between the window member and another member, wherein the sealing material is the sealing material of the present invention, and at least a part of the detection unit is positioned in a position that is exposed to the closed space when the peephole is attached to the opening, and is positioned in a position that is visible through the window member from outside the housing that is separated from the closed space by the window member.

[0008] Furthermore, according to the present invention, there is provided a battery unit comprising: a housing having an opening penetrating from the inside to the outside and defining a closed space; a cell unit arranged within the housing; and a sight glass attached to the opening and enabling the inside of the closed space to be viewed from outside the housing, wherein the sight glass comprises: a window member that is transparent to visible light; and a sealing material that seals between the window member and another member, wherein the sealing material is the sealing material of the present invention, the window member separates the closed space from the outside of the housing, and at least a portion of the detection unit is exposed to the closed space and is visible from outside the housing through the window member.

[0009] According to the present invention, it is possible to detect the generation of gas inside a housing without using electrical methods and before the housing is disassembled.

[0010] 1(a) to 1(e) are diagrams showing a sealing material according to an embodiment, where FIG. 1(a) is a perspective view, FIG. 1(b) is a view of the sealing material in the central axis direction (plan view), FIG. 1(c) is a view of the sealing material in the radial direction (side view), FIG. 1(d) is a cross-sectional view of the sealing material cut along a plane along the central axis, and FIG. 1(e) is a partially enlarged view of FIG. 1(d). FIGS. 2(a) to 2(d) are diagrams showing a battery unit according to an embodiment, where FIG. 2(a) is a plan view, FIG. 2(b) is a perspective view, FIG. 2(c) is a side view, and FIG. 2(d) is a side cross-sectional view. FIGS. 3(a) and 3(b) are enlarged views showing the observation window and its surrounding area in a battery unit according to an embodiment, where FIG. 3(a) is a perspective cross-sectional view, and FIG. 3(b) is a side cross-sectional view. FIGS. 4(a) to 4(g) are cross-sectional views showing modified sealing materials. 5(a) to 5(g) are cross-sectional views showing modified examples of the sealing material, and Fig. 5(a) to Fig. 5(g) are side cross-sectional views showing modified examples of the observation window.

[0011] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted where appropriate.

[0012] First, an embodiment will be described using FIGS. 1(a) to 3(b). In this embodiment, the sealing material 100 is formed in an annular shape. FIG. 1(b) is a view of the sealing material 100 viewed in the direction of its central axis, and FIG. 1(c) is a view of the sealing material 100 viewed in the radial direction. The posture (orientation) of the sealing material 100 when attached to an object to which it is attached is not particularly limited, but for convenience, FIG. 1(b) is a plan view, and FIG. 1(c) is a side view. FIG. 1(d) is a cross-sectional view of the sealing material 100 cut along a plane along its central axis, taken along line D-D in FIG. 1(b). FIG. 1(e) is a partially enlarged view of portion E indicated by the dashed line in FIG. 1(d). FIG. 2(d) is a side cross-sectional view of a battery unit 300 according to an embodiment, taken along line D-D in FIG. 2(a). Note that Fig. 2(d) is a cross-sectional view taken along a plane passing through the central axes of the sealing material 100 and the observation window 50. Fig. 3(b) is a partially enlarged view of part B indicated by the dashed dotted line in Fig. 2(d), and Fig. 3(a) is a perspective cross-sectional view taken at the same position as Fig. 3(b).

[0013] 1( a) to 1(e), a sealing material 100 according to this embodiment will be described. The sealing material 100 according to this embodiment includes a sealing material body 10 that performs a sealing function between components, and a detection unit 20 that changes color when it comes into contact with a gas to be detected.

[0014] According to this embodiment, the sealing material 100 includes a sealing material body 10 that performs the sealing function between components, and a detection unit 20 that changes color when it comes into contact with a gas to be detected. Therefore, by arranging the detection unit 20 in a position where it is exposed to the atmosphere in the closed space defined by the housing 210 (FIGS. 2(a) to 3(b)) and where it is visible from the outside through the observation window 50 (FIGS. 2(a) to 3(b)), it is possible to detect the generation of gas within the housing 210 without using electrical methods and before the housing 210 is disassembled. Therefore, no power source is required for gas detection.

[0015] This will be explained in more detail below.

[0016] The detection unit 20 may be of any type as long as it changes color when it comes into contact with the gas to be detected, but it is preferable that it be configured to include a metal material. In the present invention, the type of gas to be detected is not particularly limited, but in this embodiment, a case where the gas to be detected is hydrogen sulfide will be described. In this case, the metal material used for the detection unit 20 may be of any type as long as it changes color when it reacts with hydrogen sulfide, but in this embodiment, silver is used because it turns black when it reacts with hydrogen sulfide and is therefore easy to visually distinguish.

[0017] In this embodiment, the detection unit 20 is integrated with the sealing material body 10. This facilitates installation of the sealing material 100 including the detection unit 20 and the sealing material body 10, and the position of the detection unit 20 can be uniquely determined by attaching the sealing material body 10 between components. The method for integrating the detection unit 20 with the sealing material body 10 is not particularly limited. For example, the detection unit 20 and the sealing material body 10 may be integrally molded by two-color molding or insert molding. Alternatively, the detection unit 20 may be fixed to the sealing material body 10 by adhesion or bonding. Alternatively, the detection unit 20 may be formed by applying the detection unit 20 (an elastic body containing a coloring agent that changes color when it comes into contact with the gas to be detected) to the sealing material body 10 after molding the sealing material body 10 (elastic body). Alternatively, the portion of the sealing material 100 including the sealing material body 10 and the detection unit 20 may be formed from a single material, and the entire sealing material body 10 may serve as the detection unit 20. In this case, for example, the entire sealing material 100 can be the detection unit 20. However, the present invention is not limited to this example, and the detection unit 20 and the sealing material main body 10 may be configured separately. In this case, the detection unit 20 may be fixed to the sealing material main body 10 by adhesive or pasting, etc., at a position preferred by the user, or may be attached to an object to be attached (for example, the inner surface of a window member 51 described below or the inner surface of an opening 217) separately from the sealing material main body 10. In this case, for example, it is preferable that the sealing material 100 be distributed with the detection unit 20 and the sealing material main body 10 packaged together.

[0018] In this embodiment, the detection unit 20 is integrally molded with the sealing material body 10. This allows for a sealing material 100 in which the detection unit 20 and the sealing material body 10 are well integrated. As an example, the material constituting the sealing material body 10 and the material constituting the detection unit 20 are integrated by two-color molding. In this case, the sealing material body 10 is made of, for example, an elastic body. Meanwhile, the detection unit 20 is made of, for example, an elastic body containing a coloring agent that changes color when it comes into contact with the gas to be detected. However, the present invention is not limited to this example, and the sealing material 100 may be formed by insert molding in which the detection unit 20 (metal constituting the detection unit 20, or resin or elastic body containing a coloring agent constituting the detection unit 20) is inserted into the material constituting the sealing material body 10.

[0019] In this embodiment, the sealing material body 10 is a seal ring formed in an annular shape, and the detection unit 20 is positioned in a position that is visible when the seal ring is viewed from one side in the axial direction of the seal ring. Thus, by disposing the sealing material body 10 between components, a 360-degree sealing area can be easily formed. Furthermore, by disposing the sealing material 100 between components in an orientation that allows the detection unit 20 to be positioned in a position that is visible from the outside of the observation window 50 described below, the detection unit 20 can be easily viewed from outside the housing 210. The sealing material body 10 being a seal ring means that the sealing material body 10 has a closed loop shape and has an opening in its center. In this case, the shape of the sealing material body 10 is not limited as long as it has a closed loop shape, and may be, for example, a circular ring, an elliptical ring, a rectangular ring, or the like. However, the present invention is not limited to this example, and the sealing material body 10 may be formed in a shape other than a seal ring. For example, the sealing material body 10 may be formed in a string shape. In this case, the sealing material body 10 is deformed into a loop shape and disposed between components.

[0020] In this embodiment, at least a portion of the detection unit 20 is disposed on the inner circumferential side of the seal ring (sealing material body 10). This ensures good visibility of the detection unit 20 even when the outer circumferential side of the sealing material body 10 is covered by a member disposed around the sealing material 100, thereby reducing restrictions on the placement of the sealing material 100 and the shape of the member disposed around the sealing material 100. The inner circumferential side of the sealing material body 10 refers to the portion of the outer surface of the sealing material body 10 facing the central axis of the sealing material body 10. When the sealing material body 10 is an annular O-ring, the inner circumferential side of the sealing material body 10 refers to the area inside an imaginary circle having a diameter exactly midway between the outer diameter and inner diameter of the sealing material body 10 when viewed axially. In this embodiment, the entire detection unit 20 is disposed on the inner circumferential side of the sealing material body 10.

[0021] As described above, in this embodiment, the detection unit 20 is integrated with the sealing material body 10, but is disposed on at least the surface layer of the sealing material body 10. In this embodiment, the sealing material body 10 is an O-ring. That is, the sealing material body 10 is annular, and the cross-sectional shape of the sealing material body 10 cut in the axial direction of the sealing material body 10 is circular (or elliptical). The central axis of the sealing material body 10 coincides with the central axis of the sealing material 100. In this embodiment, the detection unit 20 is formed in an annular shape. The outer diameter of the detection unit 20 is equal to the inner diameter of the sealing material body 10, and the inner diameter of the detection unit 20 is smaller than the inner diameter of the sealing material body 10. The central axis of the detection unit 20 coincides with the central axis of the sealing material body 10. For example, if the central axis direction of the sealing material body 10 is referred to as the thickness direction, the dimension (thickness dimension) of the detection unit 20 in the thickness direction is smaller than the dimension (thickness dimension) of the sealing material body 10 in the same direction. The detection unit 20 is disposed in the thickness direction of the sealing material body 10 at and near the portion where the inner diameter of the sealing material body 10 is smallest. The total volume of the detection unit 20 is smaller than the total volume of the sealing material body 10, for example, half or less of the total volume of the sealing material body 10, preferably 1 / 10 or less of the total volume of the sealing material body 10, and more preferably 1 / 20 or less of the total volume of the sealing material body 10. By doing so, it is possible to reduce the amount of the detection unit 20, which is more expensive than the sealing material body 10 because it contains a metal material.

[0022] In this embodiment, the sealing material body 10 and the detection unit 20 are made of elastic materials, so that the sealing material body 10 can easily provide sealing properties.

[0023] The elastic body constituting the sealing material body 10 is made of a highly elastic material (rubber-like elastic body) such as rubber (synthetic rubber or natural rubber) or a thermoplastic elastomer (thermoplastic resin rubber elastic body), and is flexible. Examples of materials for the sealing material body 10 include rubber materials such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), fluororubber (FKM), and ethylene propylene diene rubber (EPDM).

[0024] The elastic body constituting the detection unit 20 is similar to the elastic body constituting the sealing material body 10. However, as described above, the detection unit 20 is preferably made up of a metal material that changes color when it comes into contact with the gas to be detected.

[0025] In this embodiment, the gas to be detected is hydrogen sulfide. In this case, the material of the sealing material body 10 is preferably EPDM, which has good sealing properties against hydrogen sulfide and water-based materials. In this case, the detection unit 20 is preferably configured to contain a silver filler. For example, rubber (EPDM) containing silver filler is initially yellowish-white (before contact with hydrogen sulfide) and turns black upon reaction with hydrogen sulfide.

[0026] The detection unit 20 preferably includes a polymeric material, a coloring agent that changes color upon contact with hydrogen sulfide, and a color reaction accelerator. The polymeric material herein refers to an elastic material (such as rubber or thermoplastic elastomer) that constitutes the detection unit 20. In the present invention, the detection unit 20 does not necessarily need to be elastic (i.e., a highly elastic material); the polymeric material herein may be a hard material that lacks elasticity in a crosslinked state. When the gas to be detected is hydrogen sulfide, the coloring agent is preferably at least one selected from the group consisting of silver, silver compounds, copper, copper compounds, nickel, nickel compounds, cobalt, cobalt compounds, lead, lead compounds, iron, and iron compounds. The color reaction accelerator is preferably a polar oil. The color reaction accelerator is preferably a silicone oil and / or an ester oil. It is preferable that the coloring agent is contained in an amount of 10 parts by weight to 500 parts by weight and the color reaction accelerator is contained in an amount of 0.1 parts by weight to 30 parts by weight per 100 parts by weight of the polymer material. By doing so, it is possible to detect a gas with a low concentration of hydrogen sulfide by the color change of the detection unit 20 without increasing the content of the coloring agent.

[0027] <Color Reaction Accelerator> The color reaction accelerator will be described in more detail. At least a portion of the hydrogen sulfide that comes into contact with the detection unit 20 dissolves in the color reaction accelerator contained in the detection unit 20, and the dissolved hydrogen sulfide (H ２ The present inventors presume that hydrogen sulfide (S) is ionized and then reacts with the coloring agent. In this case, the present inventors believe that since most of the hydrogen sulfide quickly dissolves in the color reaction accelerator, the detection unit 20 is likely to color or will color more quickly even if the content of the coloring agent is small.

[0028] The color reaction accelerator is not particularly limited, but is preferably an oil having polarity, i.e., a polar oil, because the color developer is easily soluble in the polar oil.

[0029] The color reaction accelerator can be silicone oil or ester oil. Among these, silicone oil and / or ester oil are preferable. The present inventors have found that the detection unit 20 using silicone oil and / or ester oil as the color reaction accelerator is more likely to develop color or develops color more quickly even with a small amount of coloring agent.

[0030] The content of the color reaction accelerator in the detection unit 20 is preferably 0.1 to 30 parts by weight per 100 parts by weight of the polymer material. If the amount of the color reaction accelerator relative to the polymer material is too large, kneading becomes difficult during the manufacturing process. On the other hand, if the amount of the color reaction accelerator relative to the polymer material is too small, the coloring agent becomes difficult to color.

[0031] <Coloring Agent> A more detailed description will be given of the coloring agent contained in the detection unit 20. The coloring agent may be any element or compound that changes color when it comes into contact with hydrogen sulfide.

[0032] The coloring agent may be a chalophilic element, a siderophilic element, or a compound thereof. The chalophilic elements include copper, zinc, gallium, germanium, arsenic, selenium, silver, cadmium, lanthanum, tin, antimony, tellurium, mercury, thallium, lead, bismuth, and polonium. The siderophilic elements include manganese, iron, cobalt, nickel, molybdenum, ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum, and gold.

[0033] Among these, the color former is preferably at least one selected from the group consisting of silver, silver compounds, copper, copper compounds, nickel, nickel compounds, cobalt, cobalt compounds, lead, lead compounds, iron, and iron compounds, and more preferably at least one selected from the group consisting of lead, lead compounds, iron, and iron compounds. The present inventors have found that the detection unit 20 using such a color former is more likely to develop color or develops color more quickly even with a small amount of color former.

[0034] The color developer is preferably in powder form.

[0035] The content of the coloring agent in the detection unit 20 is preferably 10 parts by weight or more and 500 parts by weight or less relative to 100 parts by weight of the polymer material. If the amount of the coloring reaction accelerator relative to the polymer material is too large, kneading becomes difficult during the manufacturing process. On the other hand, if the amount of the coloring reaction accelerator relative to the polymer material is too small, the coloring agent becomes difficult to color.

[0036] <Polymer Material> The polymer material contained in the detection unit 20 will be described in more detail. The polymer material is not particularly limited, and examples include conventionally known polymer materials such as diene rubber and its hydrogenated products, olefin rubber, halogen-containing rubber, silicone rubber, sulfur-containing rubber, and fluororubber. Examples of diene rubber and its hydrogenated products include natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR) (high cis BR and low cis BR), acrylonitrile butadiene rubber (NBR), hydrogenated NBR, and hydrogenated SBR. Examples of olefin-based rubbers include ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), maleic acid-modified ethylene propylene rubber (M-EPM), maleic anhydride-modified ethylene-α-olefin copolymer, ethylene-glycidyl methacrylate copolymer, maleic anhydride-modified ethylene-ethyl acrylate copolymer (modified EEA), butyl rubber (IIR), copolymer of isobutylene with aromatic vinyl or diene monomer, acrylic rubber (ACM), ionomer, etc. Examples of halogen-containing rubbers include halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR), halogenated isomonoolefin-p-alkylstyrene copolymers (e.g., brominated isobutylene-p-methylstyrene copolymer (BIMS)), halogenated isobutylene-isoprene copolymer rubber, chloroprene rubber (CR), hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), and maleic acid-modified chlorinated polyethylene (M-CM). Examples of silicone rubbers include methyl vinyl silicone rubber, dimethyl silicone rubber, and methyl phenyl vinyl silicone rubber. Examples of sulfur-containing rubbers include polysulfide rubber. Examples of fluorine-containing rubbers include vinylidene fluoride-based rubbers, fluorine-containing vinyl ether-based rubbers, tetrafluoroethylene-propylene-based rubbers, fluorine-containing silicone rubbers, and fluorine-containing phosphazene-based rubbers.

[0037] The polymer material is preferably at least one selected from the group consisting of ethylene propylene diene rubber (EPDM), silicone rubber, acrylic rubber, and fluororubber.

[0038] The detection unit 20 includes the polymer material, coloring agent, and color reaction accelerator as described above, but may also include other components, with the content of the other components being preferably 30% by mass or less, more preferably 15% by mass or less, even more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0039] When the gas to be detected is, for example, water vapor other than hydrogen sulfide, the detection unit 20 contains, for example, cobalt chloride. In this case, the detection unit 20 is initially blue (before contact with water vapor) and changes color to red upon reaction with water vapor.

[0040] Next, a battery unit 300 according to this embodiment will be described with reference to FIGS. 2A to 3B. The battery unit 300 according to this embodiment includes a housing 210 having an opening 217 penetrating the interior and exterior thereof and defining a closed space 210a, a cell unit 220 disposed within the housing 210, and a sight window 50 attached to the opening 217 and enabling the interior of the closed space 210a to be viewed from the exterior of the housing 210. The sight window 50 includes a visible light-transmitting window member 51 and a sealing material 100 that seals between the window member 51 and other members. The sealing material 100 is the sealing material 100 according to this embodiment, and the sealing material body 10 of the sealing material 100 seals between the window member 51 and other members. The window member 51 separates the closed space 210a from the exterior of the housing 210. At least a portion of the detection unit 20 is exposed to the closed space 210a and is visible from outside the housing 210 through the window member 51. Here, the entire closed space 210a may be located inside the housing 210, or a portion of the closed space 210a may be located outside the housing 210 and communicate with the internal space of the housing 210 through the opening 217. In the case of the present embodiment, a portion of the closed space 210a is located outside the housing 210 and communicates with the internal space of the housing 210 through the opening 217, and the sealing material 100 is disposed in that portion of the closed space 210a (the portion located outside the housing 210). Furthermore, "at least a portion of the detection unit 20 being exposed to the closed space 210a" means that at least a portion of the detection unit 20 is exposed to the atmosphere of the closed space 210a.

[0041] This makes it possible to visually check the color change of the detection unit 20 from outside the housing 210 through the window member 51 of the viewing window 50 of the battery unit 300, thereby determining whether or not the gas to be detected is being generated in the closed space 210a.

[0042] The portion of the battery unit 300 excluding the sealing material 100 is, for example, a battery 200 for an electric vehicle, a hybrid vehicle, or the like. The battery 200 includes a housing 210 and a cell unit 220. The cell unit 220 is a unit formed of multiple battery cells. The battery cells are, for example, lithium secondary batteries. The shape of the housing 210 is not particularly limited, but for example, the housing 210 is formed in a rectangular parallelepiped shape in plan view. In this case, the housing 210 includes a bottom plate 211, a top plate 212 disposed above the bottom plate 211 and facing the bottom plate 211 at a distance, and side walls 213 connecting the peripheries of the bottom plate 211 and the top plate 212 to each other. The side walls 213 are rectangular in plan view and include a pair of side walls disposed parallel to and facing each other, and another pair of side walls perpendicular to the pair of side walls and disposed parallel to and facing each other.

[0043] The housing 210 has an opening 217 to which the viewing window 50 is attached. There are no particular limitations on where the opening 217 is formed in the housing 210, but in the case of this embodiment, for example, the opening 217 is formed in the top plate 212. The opening 217 penetrates the top plate 212 to connect the inside and outside of the housing 210. However, the viewing window 50 is attached to the opening 217 (to the top plate 212) so as to close the opening 217, so that the opening 217 is sealed and the inside of the housing 210 becomes a closed space 210a.

[0044] Next, the sight glass 50 according to this embodiment will be described. The sight glass 50 according to this embodiment is attached to an opening 217 that penetrates the interior and exterior of the housing 210 that defines the closed space 210a, allowing the interior of the closed space 210a to be viewed from outside the housing 210. The sight glass 50 includes a visible light-transmitting window member 51 and a sealing material 100 that seals between the window member 51 and other members. The sealing material 100 is the sealing material 100 according to this embodiment, and the sealing material body 10 of the sealing material 100 seals between the window member 51 and other members. At least a portion of the detection unit 20 is positioned so as to be exposed to the closed space 210a when the sight glass 50 is attached to the opening 217, and is also positioned so as to be visible through the window member 51 from outside the housing 210, which is separated from the closed space 210a by the window member 51.

[0045] As a result, by attaching the sight glass 50 to the opening 217 of the housing 210, it is possible to visually check the detection unit 20 from outside the housing 210 and determine whether or not the gas to be detected is being generated in the closed space 210a.

[0046] As shown in FIGS. 3A and 3B , in addition to the sealing material 100 and the window member 51, the viewing window 50 includes a retaining frame 52 that presses the outer peripheral edge of the window member 51, a plurality of fastening members 54 that fasten the retaining frame 52 to the top plate 212 of the housing 210, and an annular (with a central opening) packing 53 (buffer material) that is interposed between the outer peripheral edge of the window member 51 and the retaining frame 52. In this embodiment, the opening 217 has, for example, a circular planar shape. An annular wall 55 that protrudes outward is formed on the outer surface of the top plate 212 surrounding the opening 217. The annular wall 55 also has, for example, a circular planar shape. A plurality of fixing holes 218 (female threads) are formed from the annular wall 55 to a portion of the top plate 212 directly below the annular wall 55 for fastening the retaining frame 52 to the annular wall 55 using the fastening members 54. The inner peripheral surface of the annular wall 55 and the peripheral edge of the opening 217 on the outer surface of the top plate 212 (but the portion located inside the annular wall 55) form a seal placement area 56, which is an area where the seal material 100 is placed. The seal placement area 56 is an annular (circular) area in a plan view. The seal material 100 is placed in the seal placement area 56. The inner diameter of the annular wall 55 is set to be equal to the outer diameter of the seal material 100. The height dimension of the annular wall 55 (the dimension of the annular wall 55 in the protruding direction of the annular wall 55) is set to be smaller than the dimension (thickness dimension) of the seal material 100 in the axial direction. For example, the inner diameter of the opening 217 is set to be approximately the same as the inner diameter of the seal material 100. The window member 51 is formed, for example, in a disk shape with an outer diameter slightly larger than the outer diameter of the seal material 100. The retaining frame 52 is an annular plate-shaped member with an opening 52a in the center. The inner diameter of retaining frame 52 is smaller than the outer diameter of window member 51, and the outer diameter of retaining frame 52 is larger than the outer diameter of window member 51. Retaining frame 52 presses window member 51 against sealing material 100 via packing 53. Retaining frame 52 has a plurality of insertion holes 52b formed therein for fastening retaining frame 52 to annular wall 55, and retaining frame 52 is fastened to annular wall 55 by screwing a plurality of fastening members 54 into annular wall 55 through insertion holes 52b.As a result, the lower surface of the window member 51 is pressed against the sealant 100 in a circumferential manner, and the opening 217 is airtightly sealed by the window member 51 and the seal arrangement portion 56. In this way, the sealant 100 is held in a compressed state between the peripheral edge of the lower surface of the window member 51 and the upward-facing surface of the seal arrangement portion 56 (the portion located inside the annular wall 55), and performs a sealing function between the window member 51 and the top plate 212. That is, in the case of this embodiment, the "sealing function between members" performed by the sealant 100 is a sealing function between the window member 51 and the top plate 212.

[0047] The holding frame 52, the fastening member 54, and the housing 210 (including the top plate 212 and the annular wall 55) are made of, for example, metal. The window member 51 is made of, for example, glass, but may also be made of a resin such as acrylic resin. The packing 53 is interposed between the window member 51 and the holding frame 52, thereby protecting the window member 51 from the holding frame 52. Because the packing 53 and the holding frame 52 are annular, they do not obstruct visibility of the detection unit 20 through the window member 51 (visibility from outside the viewing window 50). In other words, because the center of the window member 51 is exposed to the outside through the opening 52a of the holding frame 52 and the opening of the packing 53, the detection unit 20 can be viewed through the window member 51. Furthermore, by fastening the retaining frame 52 to the top plate 212 (the annular wall 55 thereof) using the fastening member 54, the surface pressure (contact pressure) between the sealing material 100 and the window member 51, and the surface pressure (contact pressure) between the sealing material 100 and the seal arrangement portion 56 can be sufficiently ensured, thereby achieving good sealing properties.

[0048] If a target gas (e.g., hydrogen sulfide) is generated in the closed space 210a, the color of the detection unit 20 changes (e.g., turns black), allowing the user to visually check the color of the detection unit 20 and recognize that the target gas has been generated. On the other hand, if the target gas is not generated in the closed space 210a, the color of the detection unit 20 does not change and remains the original color, allowing the user to visually check the color of the detection unit 20 and recognize that the target gas has not been generated. Therefore, the presence or absence of the target gas can be confirmed while maintaining the sealed state of the housing 210, thereby preventing the target gas from leaking from the housing 210. It is also possible to constantly check the color change of the detection unit 20 from outside the housing 210 using a camera or the like.

[0049] <Modifications of sealing material 100> Next, modifications of the sealing material 100 will be described using each of Figures 4(a) to 5(g). Each of Figures 4(a) to 5(g) is an enlarged cross-sectional view showing a portion corresponding to Figure 1(e). The sealing material 100 shown in each of Figures 4(a) to 5(g) is annular (for example, circular ring-shaped) as in the above embodiment.

[0050] The sealing material body 10 shown in FIGS. 4( a) to 4(g) is an O-ring, as in the above-described embodiment. In the example of FIG. 4(a), a recess 11 is formed on the inner periphery of the sealing material body 10 for embedding and fixing a portion of the outer periphery of the detection portion 20. This improves the integration of the detection portion 20 and the sealing material body 10. In the example of FIG. 4(b), a protrusion 12 protruding radially inward is formed on the inner periphery of the sealing material body 10, and the detection portion 20 is disposed on the surface of the protrusion 12. This further reduces the amount of material for the detection portion 20. In the example of FIG. 4(c), the detection portion 20 is applied over the entire surface of the sealing material body 10. Applying the detection portion 20 reduces the amount of material for the detection portion 20. In the example of FIG. 4(d), the detection portion 20 is applied over the entire inner periphery of the sealing material body 10, while the detection portion 20 is not formed on the outer periphery of the sealing material body 10. This allows for a further reduction in the amount of material for the detection unit 20 compared to the example in FIG. 4( c). In the example in FIG. 4( e), the area in the thickness direction of the sealing material 100 where the detection unit 20 is applied is narrower than the example in FIG. 4( d). This allows for a further reduction in the amount of material for the detection unit 20 compared to the example in FIG. 4( d). Note that, in this modification, the detection unit 20 is also disposed in a position visible through the window member 51. In the example in FIG. 4( f), the area in the thickness direction of the sealing material 100 where the detection unit 20 is applied is even narrower than the example in FIG. 4( e). This allows for a further reduction in the amount of material for the detection unit 20 compared to the example in FIG. 4( e). In this case, the detection unit 20 is disposed in a position visible through the window member 51. In the example in FIG. 4( g), the entire sealing material body 10 serves as the detection unit 20.

[0051] The sealing material body 10 shown in FIGS. 5( a) to 5( g) differs from the above embodiment in that it is formed in a shape other than an O-ring. In the example of FIG. 5( a), the cross-sectional shape of the sealing material body 10 is rectangular (e.g., square). In the example of FIG. 5( b), the cross-sectional shape of the sealing material body 10 is D-shaped with an arc-like convexity extending radially inward. That is, the sealing material body 10 in FIG. 5( b) is a D-ring. In the example of FIG. 5( c), the cross-sectional shape of the sealing material body 10 includes a rectangular portion and a rectangular support base 13 that protrudes radially inward from a portion of the inner circumferential surface of the rectangular portion. A detection unit 20 is disposed on the support base 13 at a position visible through a window member 51. In the example of FIG. 5( d), the cross-sectional shape of the sealing material body 10 is rectangular (e.g., square), and the detection unit 20 is applied to the inner circumferential surface of the sealing material body 10 and the upper surface of the sealing material body 10. In the example of Fig. 5(e), the sealing material body 10 is a D-ring, as in Fig. 5(b), and the detection unit 20 is applied to the inner peripheral surface of the sealing material body 10. In the example of Fig. 5(f), the shape of the sealing material body 10 is the same as in Fig. 5(c), and the detection unit 20 is applied to the holding table 13 at a position visible through the window member 51. In the example of Fig. 5(g), an inclined surface 14 is formed on the inner peripheral side of the sealing material body 10, in a position on the window member 51 side, that is tapered inward in the radial direction of the sealing material body 10 and away from the window member 51, and the detection unit 20 is applied to the inclined surface.

[0052] <Modification of the sight glass 50> Next, a modification of the sight glass 50 will be described using FIG. 6 . The sight glass 50 according to this modification differs from the sight glass 50 according to the above embodiment in the following respects, but is otherwise configured similarly to the sight glass 50 according to the above embodiment. In the above embodiment, an example was described in which the seal material 100 is fixed to the sight glass 50 only after the sight glass 50 is attached to the housing 210. More specifically, in the above embodiment, an example was described in which the seal material 100, the window member 51, and the packing 53 are sandwiched between the holding frame 52 and the top plate 212 (the seal arrangement portion 56 thereof) only after the sight glass 50 is attached to the housing 210. In contrast, in this modification, the sight glass 50, which has been assembled as a unit, can be fixed to the housing 210 using the fastening member 58.

[0053] In this modified example, the top plate 212 does not have the annular wall 55 and the seal arrangement portion 56, and the outer surface of the top plate 212 (at least the portion around the opening 217 where the viewing window 50 is attached) is formed flat.

[0054] On the other hand, in this modified example, the viewing window 50 further includes a mounting frame 57, which will be described below. The mounting frame 57 is a frame-shaped member disposed opposite the holding frame 52 and includes, for example, a base portion 57a ​​formed in the shape of an annular (circular) flat plate, an annular wall 55 formed on one surface of the mounting frame 57, and a seal placement portion 56 located inside the annular wall 55. The base portion 57a ​​has an opening 57b in its center. The inner diameter of the opening 57b is set to be equal to the inner diameter of the opening 217, for example. A plurality of fastening holes 57c (female threads) are formed in the base portion 57a ​​from the annular wall 55 to a portion of the base portion 57a ​​directly below the annular wall 55. The fastening holes 57c are used to fasten the holding frame 52 to the annular wall 55 using fastening members 54. A plurality of fastening holes 57d are formed in the base portion 57a ​​around the annular wall 55, for fastening the base portion 57a ​​to the top plate 212 using fastening members 58. In the area surrounding the opening 217 in the top plate 212, a plurality of fixing holes 218 (female threads) are formed at positions corresponding to the fixing holes 57d for fastening the base portion 57a ​​to the top plate 212 using a fastening member 58.

[0055] In this modified example, the sight window 50 can be integrated (unitized) in advance before being attached to the housing 210 by fastening the holding frame 52 to the mounting frame 57 using the fastening member 54. This makes it possible to allow air to pass through the sight window 50 with an appropriate surface pressure set. When the sight window 50 is attached to the housing 210, the atmosphere inside the housing 210 can pass through the opening 217 and the opening 57b to the area where the detection unit 20 is located.

[0056] Although the embodiments and modifications have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0057] For example, although the above describes an example in which the sealing material 100 has one detection unit 20, the present invention is not limited to this example, and the sealing material 100 may have multiple detection units 20. In this case, the multiple detection units 20 may be identical to each other. That is, the gases to be detected by each detection unit 20 may be the same, and the gas detection sensitivities of each detection unit 20 may also be equivalent to each other. However, the present invention is not limited to this example, and the sealing material 100 may have multiple detection units 20 with different detection sensitivities. Furthermore, the sealing material 100 may have multiple detection units 20 with different types of gases to be detected. One method for differentiating the detection sensitivities of the multiple detection units 20 is, for example, to vary the content of metal filler (e.g., silver filler) in each detection unit 20. In this case, for example, the higher the content of metal filler in a detection unit 20, the higher the gas detection sensitivity, and the lower the content of metal filler in a detection unit 20, the lower the gas detection sensitivity. Furthermore, one example of a method for causing the plurality of detection units 20 to detect different types of gases is to vary the type of metal filler contained in each detection unit 20. For example, if the gas to be detected by one detection unit 20 is hydrogen sulfide and the gas to be detected by the other detection units 20 is water vapor, one detection unit 20 may contain silver filler and the other detection units 20 may contain cobalt chloride. A detection unit 20 containing cobalt chloride is initially blue (before contact with water vapor) and changes color to red upon reaction with water vapor.

[0058] This embodiment encompasses the following technical concepts: (1) A sealing material comprising a sealing material main body that performs a sealing function between components, and a detection unit that changes color when it comes into contact with a gas to be detected. (2) The sealing material according to (1), in which the detection unit is integrated with the sealing material main body. (3) The sealing material according to (2), in which the detection unit is molded integrally with the sealing material main body. (4) The sealing material according to (2) or (3), in which the sealing material main body is an annular seal ring, and the detection unit is disposed in a position that is visible when the seal ring is viewed from one side in the axial direction of the seal ring. (5) The sealing material according to (4), in which at least a portion of the detection unit is disposed on the inner circumferential side of the seal ring. (6) The sealing material according to any one of (1) to (5), in which the detection unit includes a polymer material, a coloring agent that changes color when it comes into contact with hydrogen sulfide, and a color reaction accelerator. (7) A peephole attached to an opening penetrating the inside and outside of a housing that defines a closed space, allowing the inside of the closed space to be viewed from outside the housing, comprising: a window member that is transparent to visible light; and a sealing material that seals between the window member and another member, wherein the sealing material is a sealing material described in any one of (1) to (6), and at least a portion of the detection unit is positioned in a position that is exposed to the closed space when the peephole is attached to the opening, and is positioned in a position that is visible through the window member from outside the housing that is separated from the closed space by the window member. (8) A battery unit comprising: a housing having an opening penetrating from the inside to the outside and defining a closed space; a cell unit arranged in the housing; and a sight glass attached to the opening and enabling the inside of the closed space to be viewed from the outside of the housing, wherein the sight glass comprises: a window member that is transparent to visible light; and a sealing material that seals between the window member and another member, wherein the sealing material is the sealing material described in any one of (1) to (6), the window member separates the closed space from the outside of the housing, and at least a portion of the detection unit is exposed to the closed space and is visible from the outside of the housing through the window member.

[0059] This application claims priority based on Japanese Patent Application No. 2023-100028, filed on June 19, 2023, the disclosure of which is incorporated herein in its entirety by reference.

[0060] REFERENCE SIGNS LIST 100 Sealing material 10 Sealing material body 11 Recessed portion 12 Convex portion 13 Holding base 14 Inclined surface 20 Detection portion 50 Sight window 51 Window member 52 Holding frame 52a Opening 52b Insertion hole 53 Gasket 54 Fastening member 55 Annular wall 56 Seal arrangement portion 57 Mounting frame 57a Base portion 57b Opening 57c Fixing hole 57d Fixing hole 58 Fastening member 200 Battery 210 Housing 210a Closed space 211 Bottom plate 212 Top plate 213 Side peripheral wall 217 Opening 218 Fixing hole 220 Cell unit 300 Battery unit

Claims

1. A sealing material comprising a sealing body that performs the sealing function between components, and a detection part that changes color when it comes into contact with the target gas.

2. The sealing material according to claim 1, wherein the detection portion is integrated with the sealing material body.

3. The sealing material according to claim 2, wherein the detection portion is integrally formed with the sealing material body.

4. A sealing material as described in claim 2 or 3, wherein the sealing material body is a seal ring formed in an annular shape, and the detection portion is arranged in a position that is visible when the seal ring is viewed from one side in the axial direction of the seal ring.

5. The sealing material according to claim 4, wherein at least a portion of said detection portion is disposed on the inner periphery side of said seal ring.

6. A sealing material according to any one of claims 1 to 5, wherein the detection unit comprises a polymeric material, a coloring agent that changes color when in contact with hydrogen sulfide, and a color reaction accelerator.

7. A peep window that is attached to an opening that penetrates the inside and outside of a housing that defines a closed space and allows the inside of the closed space to be viewed from outside the housing, comprising: a window member that is transparent to visible light; and a sealing material that seals between the window member and another member, wherein the sealing material is a sealing material described in any one of claims 1 to 6, and at least a portion of the detection unit is positioned in a position that is exposed to the closed space when the peep window is attached to the opening, and is positioned in a position that is visible through the window member from outside the housing that is separated from the closed space by the window member.

8. A battery unit comprising: a housing having an opening penetrating from the inside to the outside and defining a closed space; a cell unit arranged within the housing; and a sight glass attached to the opening and enabling the inside of the closed space to be viewed from outside the housing, wherein the sight glass comprises: a window member that is transparent to visible light; and a sealing material that seals between the window member and another member, wherein the sealing material is a sealing material as defined in any one of claims 1 to 6, the window member separates the closed space from the outside of the housing, and at least a portion of the detection unit is exposed to the closed space and is visible from the outside of the housing through the window member.