gasket

Abstract

The present invention provides a gasket which is capable of suppressing a decrease in the sealing performance, while reducing the reaction force in the use state. This gasket is also capable of suppressing a decrease in the sealing performance with respect to a gas at high temperatures. A gasket (1) according to the present invention is formed of a porous body of an elastomer, and seals a gas at 300°C.

Description

Technical Field

[0004]

[0001] The present invention relates to a gasket.

Background Art

[0002] A battery module having a plurality of battery cells is provided with a gas discharge path for guiding the gas discharged from the gas discharge valves provided in each battery cell to the outside. The gas discharge valves of each battery cell communicate with the gas discharge path, and the gas discharged from the gas discharge valves of each battery cell is guided to the outside through the gas discharge path. In the battery module, when the internal pressure in the battery cell reaches a predetermined value due to the gas generated in each battery cell, the gas is discharged to the outside through the gas discharge valve. Further, a gasket is provided between the gas discharge valve of each battery cell and the gas discharge path, and the gasket seals the communication path between the gas discharge valve and the gas discharge path to prevent the gas discharged from the gas discharge valve from leaking outside the gas discharge path (see, for example, Patent Document 1). <000*01**>

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If the gas release channel is made of a resin that is easily deformed, a large reaction force on the gasket installed between the battery cell and the gas release channel during use, when compressed, may cause the gas release channel to deform or break. However, if the reaction force on the gasket installed between the battery cell and the gas release channel is reduced, there is a risk that the gas released from the gas release valve may leak outside the gas release channel. Furthermore, the gas release valve opens the battery cell when the gas inside the battery cell becomes hot and high-pressure, and the gas released from the gas release valve is hot and high-pressure gas. For this reason, the gasket is also required to have sealing performance that can seal in high-temperature gas. Thus, for gaskets used in conventional battery modules, there is a need for a configuration that can reduce the reaction force during use without reducing sealing performance, and that does not reduce sealing performance against high-temperature gas.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide a gasket that can reduce the reaction force in use, suppress a decrease in sealing performance, and suppress a decrease in sealing performance against high-temperature gases. [Means for solving the problem]

[0006] To achieve the above objective, the gasket according to the present invention is formed from a porous elastomer and seals in gas at 300°C.

[0007] In a gasket according to one aspect of the present invention, the plurality of pores in the porous body of the elastomer include pores with a diameter of 10 μm or more and 30 μm or less.

[0008] In a gasket according to one aspect of the present invention, the plurality of voids include voids in which the aspect ratio, which is the ratio of diameter a, which is the maximum diameter of the cross-section of the porous body of the elastomer, to diameter b, which is the diameter in a direction perpendicular to diameter a, is 1.3 or less.

[0009] In a gasket according to one aspect of the present invention, the plurality of voids have an aspect ratio of 1.3 or less, which is the ratio of diameter c, the maximum diameter of another cross-section perpendicular to the cross-section of the porous body of the elastomer, to diameter d, the diameter in a direction perpendicular to diameter c.

[0010] In a gasket according to one aspect of the present invention, in the cross-section, the proportion of voids with an aspect ratio of 1.3 or less is 70% or more, and in the other cross-section, the proportion of voids with an aspect ratio of 1.3 or less is 70% or more.

[0011] In a gasket according to one aspect of the present invention, the porous elastomer is a porous silicone elastomer.

[0012] A gasket according to one aspect of the present invention comprises a pair of surfaces facing away from each other and at least one through hole penetrating the pair of surfaces.

[0013] A gasket according to one aspect of the present invention is installed to seal the flow path between each of the gas release valves of a plurality of battery cells in a battery module and a gas release passage that forms a space for guiding the gas released from the plurality of gas release valves. [Effects of the Invention]

[0014] According to the present invention, it is possible to reduce the reaction force during use and suppress the deterioration of sealing performance, and also to suppress the deterioration of sealing performance against high-temperature gases. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view of a gasket according to an embodiment of the present invention. [Figure 2] This figure shows an observation cross-section of the elastomer porous body of a gasket according to an embodiment of the present invention. [Figure 3] This figure shows a cross-sectional view of an elastomer porous material formed by chemical foaming. [Figure 4]It is a perspective view of the gasket according to an embodiment of the present invention as a test example. [Figure 5] It is a schematic view of a seal performance evaluation test device for evaluating seal performance. [Figure 6] It is a cross-sectional view showing the gasket according to an embodiment of the present invention in a use state attached to a battery module having a plurality of battery cells.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a perspective view of a gasket 1 according to an embodiment of the present invention as an example of the gasket according to the present invention. The gasket 1 is a gasket formed of a porous body of an elastomer for sealing a gas at 300°C. Hereinafter, the configuration of the gasket 1 will be specifically described. Note that FIG. 1 shows a battery module as an application target of the gasket 1 described later. Also, in the drawings, when a plurality of identical components are provided, not all components are provided with reference numerals, and the reference numerals may be omitted.

[0018] The gasket 1 includes, for example, a seal surface 2 and a seal surface 3 which are a pair of surfaces facing each other, and at least one through hole 4 penetrating the pair of seal surfaces 2 and 3. As shown in FIG. 1, the gasket 1 has a plurality of through holes 4. For example, the seal surfaces 2 and 3 each extend along a plane, and the gasket 1 has a plate-like shape. Specifically, for example, the seal surface 2 extends parallel or substantially parallel to the plane, and the seal surface 3 extends parallel or substantially parallel to the seal surface 2. Also, in the gasket 1, the plurality of through holes 4 are arranged in a line, for example, and the gasket 1 extends in the arrangement direction of the through holes 4. ]>

[0019] Gasket 1 is designed such that, for example, the pressure loss of the fluid passing through it is greater than or equal to a predetermined value ΔP. In other words, the porous elastomer material forming the gasket (hereinafter referred to as the porous elastomer material) is designed so that the pressure loss is greater than or equal to a predetermined value ΔP. The predetermined value ΔP of pressure loss is the value that enables gasket 1 to seal a gas at a high pressure of 300°C in the usage state of gasket 1 described later. The predetermined value ΔP of pressure loss can be set to various values ​​depending on the various components of gasket 1, such as the specific shape of gasket 1. Furthermore, the predetermined value ΔP of pressure loss can be set to various values ​​depending on the specific usage mode of gasket 1. Factors considered in setting the predetermined value ΔP of pressure loss include, for example, the length and cross-sectional area of ​​the flow path from the through-hole 4 of gasket 1 to the outside. The flow path from the through-hole 4 of gasket 1 to the outside is the path of the leak of the sealed object in gasket 1 if leakage of the sealed object occurs in gasket 1 in the usage state.

[0020] Gasket 1 has small pores in an elastomer porous material such that the pressure loss is a predetermined value ΔP. Specifically, for example, the pores in gasket 1 include pores with a diameter of 10 μm or more and 30 μm or less. Most of the pores in gasket 1 are pores with a diameter of 10 μm or more and 30 μm or less. For example, more than 50% of the pores in gasket 1 are pores with a diameter of 10 μm or more and 30 μm or less.

[0021] In addition, the cross-sectional shape of each pore of the gasket 1 is, for example, a perfect circle or a substantially perfect circle. Also, the shape of each pore of the gasket 1 is, for example, a perfect sphere or a substantially perfect sphere. Specifically, for example, the plurality of pores of the gasket 1 include pores with an aspect ratio that is the ratio of the diameter a, which is the maximum diameter of a predetermined cross-section (first cross-section) of the elastomeric porous body, to the diameter b, which is the diameter in the direction orthogonal to the diameter a, and is 1.3 or less. Specifically, for example, in the pores observed in a planar or substantially planar cross-section (first observation cross-section) formed in the elastomeric porous body used to form the gasket 1, there are pores with a first aspect ratio that is the ratio of the diameter a, which is the maximum diameter, to the diameter b, which is the diameter in the direction orthogonal to the diameter a, and is 1.3 or less. The measurement of the diameters a and b of the pores is performed, for example, using an image obtained by magnifying the first observation cross-section at a predetermined magnification.

[0022] Thus, when the pores observed on the first observation surface of the elastomeric porous body include pores with a first aspect ratio of 1.3 or less, it can be determined that the elastomeric porous body has pores with a cross-section that is a perfect circle or a substantially perfect circle.

[0023] Also, specifically, for example, the plurality of pores of the gasket 1 include pores with a second aspect ratio that is the ratio of the diameter c, which is the maximum diameter of another cross-section (second cross-section) orthogonal to the first cross-section, to the diameter d, which is the diameter in the direction orthogonal to the diameter c, and is 1.3 or less. Specifically, for example, in the pores observed in a planar or substantially planar cross-section (second observation cross-section) formed in the elastomeric porous body used to form the above-mentioned gasket 1 and orthogonal to the first observation cross-section, there are pores with a second aspect ratio that is the ratio of the diameter c, which is the maximum diameter, to the diameter d, which is the diameter in the direction orthogonal to the diameter c, and is 1.3 or less. The measurement of the diameters c and d of the pores is performed, for example, using an image obtained by magnifying the second observation cross-section at a predetermined magnification.

[0024] Thus, in addition to the first observation surface, when the pores observed on the second observation surface orthogonal to the first observation surface include pores with a second aspect ratio of 1.3 or less, it can be determined that the elastomeric porous body has pores that are perfect spheres or substantially perfect spheres.

[0025] Furthermore, specifically, for example, in the first cross-section, the proportion of voids with a first aspect ratio of 1.3 or less is 70% or more, and in the second cross-section, the proportion of voids with a second aspect ratio of 1.3 or less is 70% or more. Specifically, for example, in the voids observed on the first observation surface, the number of voids with a first aspect ratio of 1.3 or less is 70% or more of the total number of voids, and in the voids observed on the second observation surface, the number of voids with a second aspect ratio of 1.3 or less is 70% or more of the total number of voids. In this case, it can be determined that the elastomer porous material has a large number of spherical or nearly spherical voids.

[0026] The elastomeric porous body that forms gasket 1 is, for example, a porous body made from an elastomer produced via an emulsion composition in which a liquid rubber material that hardens to produce an elastomer is a continuous phase. The liquid rubber material is, for example, a liquid silicone rubber material, and the elastomer is, for example, a silicone elastomer. The elastomeric porous body can be produced, for example, by known methods.

[0027] Next, an example of an elastomer porous body that forms gasket 1 and a method for manufacturing the same will be described. As an example, the elastomer porous body is a porous body of silicone elastomer (hereinafter also referred to as a silicone elastomer porous body).

[0028] A porous silicone elastomer can basically be made from a liquid silicone rubber material that hardens to produce a silicone elastomer, and a water-in-oil emulsion containing water or an aqueous solvent such as alcohol as a dispersed phase. For example, a porous silicone elastomer can be made by thoroughly stirring a liquid silicone rubber material with water under reduced pressure to form an emulsion, and then immediately heating and curing it.

[0029] Furthermore, a water-in-oil emulsion containing a liquid silicone rubber material that hardens to produce a silicone elastomer, along with water and a silicone oil material having surfactant properties, can be produced under reduced pressure, and a porous silicone elastomer body can be produced via this emulsion.

[0030] There are no particular restrictions on the liquid silicone rubber material as long as it hardens upon heating to produce a silicone elastomer, but it is preferable to use so-called addition-curing type liquid silicone rubber.

[0031] Furthermore, as mentioned above, in order to produce an elastomer porous body having spherical or nearly spherical pores, it is necessary to prepare the emulsion composition under reduced pressure. Specifically, the emulsion composition is prepared by performing the process of mixing and stirring the raw materials to form an emulsion under reduced pressure. Adding a step to degas the prepared emulsion composition under reduced pressure is insufficient.

[0032] Silicone oil materials with surfactant properties act as dispersion stabilizers to stably disperse water in emulsions. In other words, these surfactant-possessing silicone oil materials exhibit affinity not only to water but also to liquid silicone rubber materials.

[0033] In water-in-oil emulsions, water exists as a discontinuous phase (dispersed phase) in the form of particles (water droplets). The particle size of these water particles substantially determines the diameter of the pores in the porous silicone elastomer material.

[0034] In a water-in-oil emulsion, for example, to obtain an emulsion with excellent water dispersion stability, 0.2 to 10 parts by weight of a silicone oil material having surfactant properties and 10 to 250 parts by weight of water are used per 100 parts by weight of liquid silicone rubber material. By using such an emulsion with excellent water dispersion stability, a good porous material can be manufactured even more stably.

[0035] Furthermore, if the liquid rubber material is not silicone, the emulsion composition may be prepared by using the liquid rubber material as the continuous phase, a solvent that separates from the continuous phase as the dispersed phase, and adding a surfactant or a substance with surfactant properties as needed to form an emulsion.

[0036] Emulsion compositions can be manufactured by various methods. For example, a water-in-oil emulsion composition containing a silicone elastomer is generally manufactured by mixing a liquid silicone rubber material, a silicone oil material with surfactant properties, and water, along with additional additives as needed, under reduced pressure and stirring thoroughly.

[0037] To manufacture a porous silicone elastomer, for example, an emulsion composition is first subjected to primary heating. In primary heating, a heating temperature of, for example, 130°C or lower is used to heat-cur the liquid silicone rubber material without volatilizing the water in the emulsion. The heating temperature during primary heating is, for example, 80°C or higher, and the heating time is, for example, 5 to 60 minutes. This primary heating cures the liquid silicone rubber material, trapping the water particles in the emulsion in their emulsion state. The cured silicone rubber hardens to a degree that it can withstand the expansion force during the evaporation of water caused by secondary heating. Secondary heating is performed to remove the water from the cured silicone rubber that has trapped the water particles. This secondary heating is performed at a temperature of, for example, 70°C to 300°C. If the heating temperature is below 70°C, it will take a long time to remove the water, and if the heating temperature exceeds 300°C, the cured silicone rubber may deteriorate. With heating at 70°C to 300°C, the water will volatilize and be removed in 1 to 24 hours. Secondary heating removes moisture by evaporation and also achieves the final curing of the silicone rubber material. As the moisture evaporates, pores with a diameter approximately equal to that of water particles remain in the cured silicone rubber material (silicone elastomer).

[0038] Thus, the elastomeric porous body that forms the gasket 1 can be manufactured from an emulsion composition without foaming phenomena such as chemical foaming. The dispersed phase, such as water particles in the emulsion composition, is trapped in the elastomer hardened by primary heating and simply volatilizes during secondary heating. A method for manufacturing an elastomeric porous body having many small-diameter pores that are spherical or nearly spherical is disclosed, for example, in International Publication No. WO2009 / 069803.

[0039] The porous silicone elastomer manufactured by the above-described manufacturing method has a cross-section (observation cross-section) as shown in Figure 2, for example, and contains many fine spherical or nearly spherical pores with a diameter of 10 μm to 30 μm. On the other hand, as shown in Figure 3, the diameter of the pores is larger in the porous elastomer formed by chemical foaming. Figures 2 and 3 show photographs of the observation cross-sections, respectively.

[0040] Next, the sealing performance of the gasket 1 according to the embodiment of the present invention will be described.

[0041] The inventors manufactured gasket 1 (Test Example 1) by molding an elastomer porous body into a desired shape using the above-described method for manufacturing elastomer porous bodies. Figure 4 is a perspective view of gasket 1 as Test Example 1. As shown in Figure 4, Test Example 1 has a rectangular plate-like outer shape with a pair of surfaces (seals 2A, 3A), and also has through holes 4A that penetrate the sealing surfaces 2A, 3A. Test Example 1 was manufactured specifically as described later.

[0042] 100 parts by weight of liquid silicone rubber (product name DY35-7002) manufactured by Toray Dow Corning was mixed with 5 parts by weight of filler and 5 parts by weight of surfactant-containing silicone oil to obtain a mixture. Next, 140 parts by weight of water was gradually added to this mixture while stirring to prepare a water-in-oil emulsion composition. This water-in-oil emulsion composition was prepared under a reduced pressure of -98 kPa in a vacuum stirring apparatus.

[0043] The emulsion obtained in this way was poured into a mold corresponding to the shape of Test Example 1, and heated at a set temperature of 130°C for 40 minutes (primary heating) to form an intermediate. The obtained intermediate was heated in an electric furnace at 200°C for 6 hours (secondary heating) to remove water from the intermediate and obtain Test Example 1.

[0044] On the other hand, a porous silicone elastomer, which is a chemical foam, was designated as Comparative Example 1. Comparative Example 1 had the same or substantially the same shape as Test Example 1. The porous silicone elastomer of Comparative Example 1 was produced by mixing and foaming KE-951U silicone rubber manufactured by Shin-Etsu Chemical Co., Ltd., a suitable vulcanizing agent, and a chemical blowing agent.

[0045] Test Example 1 was cut in two mutually orthogonal directions, and each cut surface was observed using an electron microscope (JEOL JSM5600), and images were taken of the state in which there were 40 to 80 voids (see Figure 2). Similarly, Comparative Example 1 was cut in two mutually orthogonal directions, and each cut surface was observed using an electron microscope (JEOL JSM5600), and images were taken of the state in which there were 40 to 80 voids (see Figure 3). Then, from the images of each cut surface (SEM photograph), predetermined rectangular regions containing voids that could be observed in their entirety were designated as the first observation region and the second observation region, respectively, and the following measurements were performed on the voids contained in each rectangular region. Note that in the first and second observation regions, all voids that fell on the boundary line were included in the observation region.

[0046] The captured images were imported into the Microsoft software lenaraf200, which runs on Microsoft Excel. A reference length was set, and the circumference of each void within each observation area was traced to extract the shape of each void and calculate its aspect ratio. Specifically, in the first observation area, approximately 20 points were marked for each void to extract its shape. The diameter a of the largest void shape and the diameter b perpendicular to this largest diameter were read, and the aspect ratio a / b of the void was calculated. Similarly, in the second observation area, approximately 20 points were marked for each void to extract its shape. The diameter c of the largest void shape and the diameter d perpendicular to this largest diameter were read, and the aspect ratio c / d of the void was calculated. The calculation results are shown in Table 1.

[0047] [Table 1] As shown in Table 1, the maximum diameter a of Test Example 1 was between 10 μm and 30 μm. The maximum diameter b of Test Example 1 was between 10 μm and 30 μm. Thus, the maximum diameters (diameters a, b) of all extracted pores were between 10 μm and 30 μm. Furthermore, the maximum diameter c of Test Example 1 was between 10 μm and 30 μm. Furthermore, the maximum diameter d of Test Example 1 was between 10 μm and 30 μm. Thus, the maximum diameters (diameters c, d) of all extracted pores were between 10 μm and 30 μm. Additionally, 70% or more of the aspect ratio a / b of the pores in Test Example 1 was 1.3 or less. Furthermore, 70% or more of the aspect ratio c / d of the pores in Test Example 1 was 1.3 or less. Thus, more than 70% of the voids in Test Example 1 can be judged to be spherical or nearly spherical, and the majority of the voids in Test Example 1 can be judged to be spherical or nearly spherical.

[0048] On the other hand, the largest diameter a of Comparative Example 1 was approximately 100 μm. The largest diameter b of Comparative Example 1 was also approximately 100 μm. The largest diameter c of Comparative Example 1 was also approximately 100 μm. The largest diameter d of Comparative Example 1 was also approximately 100 μm. Furthermore, less than 30% of the aspect ratio a / b of the pores in Comparative Example 1 was 1.3 or less. Furthermore, less than 30% of the aspect ratio c / d of the pores in Comparative Example 1 was 1.3 or less. Thus, more than 70% of the pores in Comparative Example 1 can be judged to be flattened, and the majority of the pores in Comparative Example 1 can be judged to be flattened.

[0049] Next, an evaluation test of the seal performance was performed on Test Example 1 and Comparative Example 1. Figure 5 is a schematic diagram of the seal performance evaluation test apparatus 100 for evaluating the seal performance. As shown in Figure 5, the seal performance evaluation test apparatus 100 has a pair of jigs 101 and 102 and a heater 103 attached to jig 102. Guide passages 104 and 105 for guiding fluid are formed between jig 101 and jig 102, respectively. Guide passage 104 terminates at jig 101, and guide passage 105 is capable of supplying fluid to guide passage 104 of jig 101. Test Example 1 or Comparative Example 1 is sandwiched between jig 101 and jig 102, and Test Example 1 or Comparative Example 1 seals the guide passages 104 and 105 between jig 101 and jig 102. In other words, the sealing surface 2A of Test Example 1 is in contact with the surface 101a of the jig 101, and the sealing surface 3A of Test Example 1 is in contact with the surface 102a of the jig 102, so that Test Example 1 is compressed between the jig 101 and the jig 102. Also, guide passages 104 and 105 are opened in the through hole 4A of Test Example 1. Comparative Example 1 is also installed between the jig 101 and the jig 102 in the same way as Test Example 1.

[0050] In the sealing performance evaluation test, the gas guided into the guide passages 104 and 105 by the heater 103 was heated to room temperature (25°C) and high temperature (300°C), and the gas supply pressure at which leakage occurred from the gaskets (Test Example 1 and Comparative Example 1) for both room temperature and high temperature gases was measured. Table 2 shows the results of the sealing performance evaluation test.

[0051] [Table 2] As shown in Table 2, in Test Example 1, leakage of room temperature gas occurred when the gas supply pressure was 300 kPa. Also in Test Example 1, leakage of high-temperature gas occurred when the gas supply pressure was 450 kPa. On the other hand, in Comparative Example 1, leakage of room temperature gas occurred when the gas supply pressure was 100 kPa. Also in Comparative Example 1, leakage of high-temperature gas occurred when the gas supply pressure was 50 kPa.

[0052] Thus, in Test Example 1, the pressure at which leakage of room-temperature gas occurs is higher than the pressure at which leakage of room-temperature gas occurs in Comparative Example 1. Furthermore, in Test Example 1, the pressure at which leakage of high-temperature gas occurs is higher than the pressure at which leakage of high-temperature gas occurs in Comparative Example 1. In addition, in Test Example 1, the pressure at which leakage of high-temperature gas occurs is higher than the pressure at which leakage of room-temperature gas occurs. Because the diameter of the pores in Test Example 1 is small and the airtightness of Test Example 1 is high, when a high-temperature environment is created in which high-temperature gas flows through guide passages 104 and 105, the pores inside Test Example 1 expand due to thermal expansion, temporarily increasing the internal stress of Test Example 1. As a result, the deformation of Test Example 1 when subjected to pressure is suppressed, that is, the reaction force of Test Example 1 increases, and the sealing performance of Test Example 1 becomes higher than at room temperature. In contrast, in Comparative Example 1, the pressure at which leakage of high-temperature gas occurs is lower than the pressure at which leakage of room-temperature gas occurs.

[0053] As described above, the elastomer porous material of gasket 1 according to the embodiment of the present invention (Test Example 1) can improve sealing performance against high-temperature gases and can seal gas at 300°C. Furthermore, the elastomer porous material of gasket 1 according to the embodiment of the present invention (Test Example 1) can improve sealing performance as the temperature of the gas being sealed increases. On the other hand, the conventional porous material (Comparative Example 1) shows a decrease in sealing performance as the temperature of the gas being sealed increases.

[0054] Next, the operation of the gasket 1 according to an embodiment of the present invention will be described. Figure 6 is a cross-sectional view showing the gasket 1 in use, attached to a battery module 50 having a plurality of battery cells 51. As shown in Figure 6, each battery cell 51 is provided with a gas release valve 52, and the battery module 50 has a discharge pipe 53 in which a gas release passage 54 is formed to guide the gas released from the gas release valve 52 of each battery cell 51 to the outside. The discharge pipe 53 is provided with an opening 55 corresponding to the gas release valve 52 of each battery cell 51. In the discharge pipe 53, the gas release passage 54 is designed to guide the gas that flows in from each opening 55 to the outside. The discharge pipe 53 is made of resin. An insulating resin 56 is interposed between the battery cells 51, and the plurality of battery cells 51 are connected to form a battery cell group 57.

[0055] As shown in Figure 6, in operation, the gasket 1 is sandwiched between the battery cell group 57 and the discharge pipe 53, sealing the flow path between each gas discharge valve 52 and the corresponding opening 55 of the discharge pipe 53. Specifically, the sealing surface 2 of the gasket 1 contacts the surface 53a of the discharge pipe 53, and the sealing surface 3 of the gasket 1 contacts the surface 57a of the battery cell group 57, and the gasket 1 is compressed between the battery cell group 57 and the gas discharge valve 52. The gas discharge valve 52 and the opening 55 are housed in and open in each of the through holes 4 of the gasket 1. In this way, the gasket 1 ensures that the gas discharged from the gas discharge valve 52 flows into the discharge pipe 53 without leakage.

[0056] Gasket 1 is the aforementioned elastomer porous material, and has pores with a diameter of 10 μm to 30 μm inside. Since most of the pores inside gasket 1 are such extremely small pores, it has higher airtightness than conventional gaskets formed from foam, such as in Comparative Example 1. This is because the pressure loss in the flow path that penetrates the inside of gasket 1 is large. On the other hand, because gasket 1 is a porous material, the reaction force generated when compressed is smaller than the reaction force generated by a gasket formed from solid rubber. Therefore, even if a low-strength resin component such as the discharge pipe 53 is the contact surface of the sealing surfaces 2 and 3, the reaction force applied to the discharge pipe 53 can be reduced, and damage to the discharge pipe 53 can be prevented. On the other hand, even if the reaction force applied to the discharge pipe 53 is low, as described above, the airtightness of gasket 1 is high, and a decrease in sealing performance can be prevented or suppressed.

[0057] Furthermore, the Poisson's ratio of gasket 1 is smaller than that of gaskets made from solid rubber, which helps to prevent the compressed gasket 1 from deforming and interfering with other parts during use.

[0058] Furthermore, as mentioned above, the sealing performance of gasket 1 improves when the gas being sealed becomes hot. In the battery module 50, the gas release valve 52 opens when the gas inside the battery cell 51 becomes hot and high pressure. Therefore, sealing of gasket 1 in the battery module 50 is only necessary when the gas inside the battery cell 51 becomes hot. On the other hand, when the gas inside the battery cell 51 is not hot, sealing of gasket 1 is unnecessary. For this reason, gasket 1, which has a low reaction force in operating conditions and high sealing performance against hot sealed objects, is suitable as the gasket for the gas release valve 52 of the battery module 50.

[0059] Furthermore, the battery cell 51 and the discharge pipe 53 are fixed to each other by a snap-fit ​​connection, for example, using a resin claw and a recess that engages with it. For this reason, the gasket sandwiched between the battery cell 51 and the discharge pipe 53 is required to have a low reaction force generated in the operating state. As described above, the reaction force of the gasket 1 in the operating state is low, and in this respect as well, the gasket 1 is suitable as the gasket for the gas discharge valve 52 of the battery module 50.

[0060] Furthermore, the pores in the elastomer porous material of gasket 1 include perfectly spherical or nearly perfectly spherical pores. Perfectly spherical pores are less prone to stress concentration when gasket 1 is compressed. Therefore, perfectly spherical pores are less likely to break due to deformation. Thus, although gasket 1 is a porous material, it is less likely to break due to deformation.

[0061] As described above, the gasket 1 according to the embodiment of the present invention can reduce reaction force during use and suppress a decrease in sealing performance, and can also suppress a decrease in sealing performance against high-temperature, high-pressure gases.

[0062] Although the present invention has been described above through the embodiments described above, the technical scope of the present invention is not limited to the scope described in the embodiments above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the embodiments described above. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0063] The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit its interpretation. Furthermore, the embodiments described above do not limit the scope of application of the present invention, and the present invention may encompass anything as its target application. The components of the above embodiments, as well as their arrangement, materials, conditions, shapes, and sizes, are not limited to those exemplified and can be modified as appropriate. For example, the present invention includes differences that arise in the implementation of manufacturing tolerances, etc. Furthermore, components shown in different embodiments can be partially substituted or combined to the extent that they do not contradict each other in a technical sense. In addition, each configuration can be selectively combined as appropriate to achieve at least some of the problems and effects described above. [Explanation of Symbols]

[0064] 1 Gasket, 2,2A,3,3A Sealing surface, 4,4A Through hole, 50 Battery module, 51 Battery cell, 52 Gas release valve, 53 Release pipe, 53a Surface, 54 Gas release passage, 55 Opening, 56 Resin, 57 Battery cell group, 57a Surface, 100 Seal performance evaluation device, 101,102 Jig, 101a,102a Surface, 103 Heater, 104,105 Guide passage

Claims

1. A gasket formed from a porous elastomer, for sealing gas at 300°C, The plurality of pores in the porous body of the elastomer include pores in which the aspect ratio, which is the ratio of diameter a, the maximum diameter of the cross-section of the porous body of the elastomer, to diameter b, the diameter in a direction perpendicular to diameter a, is 1.3 or less. gasket.

2. The plurality of pores in the porous body of the elastomer include pores with a diameter of 10 μm or more and 30 μm or less. The gasket according to claim 1.

3. The plurality of voids have an aspect ratio of 1.3 or less, which is the ratio of the diameter c, which is the maximum diameter of another cross-section perpendicular to the cross-section of the porous body of the elastomer, to the diameter d, which is the diameter in a direction perpendicular to the diameter c. gasket according to claim 1

4. In the aforementioned cross-section, the proportion of voids with an aspect ratio of 1.3 or less is 70% or more, and in the other cross-sections, the proportion of voids with an aspect ratio of 1.3 or less is 70% or more. The gasket according to claim 3.

5. The porous elastomer is a porous silicone elastomer. The gasket according to claim 1.

6. A pair of faces that are facing away from each other, It comprises at least one through hole that penetrates the pair of surfaces, The gasket according to claim 1.

7. It is installed to seal the flow path between each of the gas release valves of the multiple battery cells of the battery module and the gas release path that forms a space for guiding the gas released from the multiple gas release valves, The gasket according to claim 6.

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