Seal structure

Abstract

The present invention comprises: a first member (1) having a male-side seal surface (15) and a male-side fitting part (14); a second member (2) having a female-side seal surface (25) and a female-side fitting part (24); and a seal washer (3) sandwiched between the male-side seal surface and the female-side seal surface. A first gap part (A1) and a second gap part (A2) having a wider interval than the first gap part are formed between the male-side seal surface and the female-side seal surface. An inner seal part (32) of the seal washer spans the first gap part and the second gap part. In a circumferential cross section of the inner seal part, whichever among the maximum thickness part (32c) in a free state and the center of gravity (32d) of the inner seal part is positioned on at least the inside in the radial direction is positioned in the second gap part.

Description

Seal structure CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-107321, filed on July 3, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a seal structure.

[0003] Patent Documents 1 to 3 disclose the use of a seal washer with an annular retainer and an annular seal portion in a pipe joint used to connect refrigerant pipes in a refrigeration cycle. This pipe joint fastens the male and female members with a bolt while the seal washer is interposed between them, thereby compressing the seal portion between the male and female members and creating a seal between the male and female members.

[0004] US Patent No. 8,186,691 JP 2016-136049 A JP 2018-48653 A

[0005] However, in the configurations of Patent Documents 1 to 3, a large reaction force is generated at the seal portion when fastening the male and female components. This requires a large bolt axial force to fasten the male and female components, and insufficient bolt axial force results in poor sealing. Furthermore, the configurations of Patent Documents 1 to 3 involve one-sided fastening, in which the fastening bolt fastens the male and female components at a position away from the seal washer, making it easy for the male and female components to be fastened at an angle. When the male and female components are fastened at an angle, there is a risk of bolt damage or poor sealing due to insufficient fastening force.

[0006] In Patent Documents 2 and 3, a gap is provided between the seal portion of the seal washer and the seal washer mounting location, and internal fluid pressure is applied to the seal portion so that sealing performance can be ensured even with low bolt axial tension. However, with the configurations in Patent Documents 2 and 3, when internal fluid pressure is applied to the seal portion, the seal portion cannot fully adapt to the elongation of the bolt and the warping of the male and female components, which could shorten the seal life.

[0007] In view of the above, the present disclosure aims to improve sealing performance while reducing the force required to fasten a male member and a female member in a seal structure that seals between a male member and a female member using a seal washer.

[0008] To achieve the above object, one aspect of the present disclosure includes a first member, a second member, and a seal washer. The first member has a male seal surface and a male mating portion formed on the male seal surface so as to protrude from the male seal surface. The second member has a female seal surface opposing the male seal surface and a female mating portion formed on the female seal surface so as to allow the male mating portion to be inserted. The seal washer has an annular retainer and an annular inner seal portion provided on the inner periphery of the retainer, and is sandwiched between the male seal surface and the female seal surface while being positioned on the outer periphery of the male mating portion.

[0009] The first and second members are fastened together so that they approach each other and compress the inner seal portion at the male and female seal surfaces. The inner seal portion seals closely against the male and female seal surfaces. A first gap is formed between the male and female seal surfaces, where the male and female seal surfaces are arranged parallel to each other with a predetermined gap therebetween, and a second gap is formed on the side closer to the male and female mating portions than the first gap, where the gap is wider than the predetermined gap. The inner seal portion is disposed across the first and second gaps. In a circumferential cross section of the inner seal portion, at least the portion of the inner seal portion with the maximum thickness in its free state and the center of gravity of the inner seal portion, whichever is located radially inward, is located in the second gap.

[0010] As a result, when the first and second members are fastened together, the inner seal portion enters the second gap, reducing the amount of deformation and allowing it to deform with low reaction force. As a result, the fastening force between the first and second members can be reduced, ensuring sufficient sealing performance with a small axial force.

[0011] 14. A plan view of a pipe fitting of the first embodiment. A cross-sectional view taken along II-II in FIG. 1. A plan view of a seal washer. A cross-sectional view taken along IV-IV in FIG. 3. A perspective cross-sectional view of the seal washer of the first embodiment. A cross-sectional view showing a state in which the seal washer of the first embodiment is sandwiched between a male seal surface and a female seal surface. A view for explaining a gap formed between the male seal surface and the female seal surface. A view for explaining an inner seal portion in a free state of the first embodiment. A view showing a state before the male member and the female member are assembled. A cross-sectional view showing changes when the seal washer of the first embodiment is compressed by the male member and the female member. A view showing a state in which internal pressure acts on the seal washer. A view showing reaction force measurement results for the seal washers of the first embodiment and a comparative example. A view showing results of a high-temperature storage test performed on the seal washers of the first embodiment and a comparative example. A plan view of a seal washer of the second embodiment. A cross-sectional view taken along XV-XV in FIG. 14. A perspective cross-sectional view of the seal washer of the second embodiment. A view for explaining an inner seal portion and an outer seal portion in a free state of the second embodiment. FIG. 1 is a cross-sectional view showing changes when the seal washer of the second embodiment is compressed by the male member and the female member. FIG. 2 is a view showing a state in which internal pressure acts on the seal washer of the second embodiment. FIG. 3 is a cross-sectional view of a pipe fitting of the third embodiment. FIG. 4 is a view showing a state before the male member and the female member of the third embodiment are assembled. FIG. 5 is a view showing low-temperature sealing properties and refrigerant gas permeability of the third embodiment and a comparative example. FIG. 6 is a cross-sectional view showing a modified inner seal portion. FIG. 7 is a cross-sectional view showing a modified inner seal portion. FIG. 8 is a cross-sectional view showing a modified inner seal portion. FIG. 9 is a cross-sectional view showing a modified inner seal portion. FIG. 10 is a cross-sectional view showing a modified outer seal portion. FIG. 11 is a cross-sectional view showing a modified outer seal portion. FIG. 12 is a cross-sectional view showing a modified outer seal portion.

[0012] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate explanations may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0013] First Embodiment A first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 11 . The seal structure of the present disclosure can be used in a mechanical fastening part that fastens two members to separate two spaces. The seal structure seals between the two members and restricts fluid movement between one space and the other. The seal structure suppresses fluid movement based on a pressure difference between the two spaces, fluid movement based on a fluid concentration difference between the two spaces, or the intrusion of foreign matter (e.g., water) from the outside. The seal structure can be used with gases, liquids, and mixed fluids of gas and liquid.

[0014] For example, the fluid used in the sealing structure may be gases such as water vapor, air, oxygen, carbon dioxide, nitrogen, hydrogen, rare gases, ammonia, hydrocarbons or mixtures thereof, fluorine-based gases, hydrogen fluoride, etc., or liquids obtained by liquefying these gases, mineral oil, synthetic oil, animal or vegetable oil, alcohols, phenols, ethers, organic or inorganic acids, or mixed liquids of these liquids.

[0015] In the first embodiment, the seal structure of the present disclosure is applied to a pipe joint 100 of a refrigeration cycle. The pipe joint 100 seals between refrigerant passages 13, 23 of the refrigeration cycle and the outside (atmosphere).

[0016] Although not shown in the figures, the refrigeration cycle is a vapor compression refrigeration cycle whose main components include a compressor that compresses the refrigerant, a condenser that condenses the refrigerant, and an evaporator that evaporates the refrigerant. The refrigeration cycle can be used in an air conditioning system for a moving body such as a vehicle. The pipe fitting 100 of this embodiment is used to connect refrigerant pipes through which a refrigerant flows. The refrigerant used in the refrigeration cycle, which is the fluid used in the pipe fitting 100, can be, for example, a fluorine-based gas refrigerant such as HFO-1234yf, or a natural refrigerant such as a CO2 refrigerant or propane refrigerant.

[0017] 1 and 2, the pipe fitting 100 includes a male member 1, a female member 2, a seal washer 3, and a fastening bolt 5. In this embodiment, an aluminum alloy is used for the male member 1 and the female member 2. The male member 1 is the first member, and the female member 2 is the second member.

[0018] The seal washer 3 provides a seal between the male member 1 and the female member 2. The fastening bolt 5 is a fastening member that fastens the male member 1 and the female member 2 together. In this embodiment, the male member 1 and the female member 2 are joined by bolt fastening. By tightening the fastening bolt 5, the male member 1 and the female member 2 are brought closer to each other, and the male member 1 and the female member 2 can be fastened together.

[0019] The male member 1 is formed with a male pipe insertion portion 12 into which the male refrigerant pipe 11 is inserted. With the end of the male refrigerant pipe 11 inserted into the male pipe insertion portion 12, the male member 1 and the male refrigerant pipe 11 are materially joined by brazing or welding. Therefore, the male member 1 and the male refrigerant pipe 11 are configured as a single component. However, the male member 1 and the male refrigerant pipe 11 may be mechanically joined by crimping or the like without being materially joined.

[0020] The female member 2 is formed with a female pipe insertion portion 22 into which the female refrigerant pipe 21 is inserted. With the end of the female refrigerant pipe 21 inserted into the female pipe insertion portion 22, the female member 2 and the female refrigerant pipe 21 are materially joined by brazing or welding. Therefore, the female member 2 and the female refrigerant pipe 21 are configured as a single component. Note that the female member 2 and the female refrigerant pipe 21 may not be materially joined, but may be mechanically joined by crimping or the like.

[0021] A first refrigerant passage 13 through which a refrigerant can flow is formed inside the male member 1. The first refrigerant passage 13 is connected to the male refrigerant pipe 11. A second refrigerant passage 23 through which a refrigerant can flow is formed inside the female member 2. The second refrigerant passage 23 is connected to the female refrigerant pipe 21.

[0022] A convex male fitting portion 14 is formed on the surface of the male member 1 facing the female member 2, protruding toward the female member 2. In this embodiment, the male fitting portion 14 is cylindrical, and a first refrigerant passage 13 is provided inside.

[0023] A female fitting portion 24 into which the male fitting portion 14 can be inserted is formed on the surface of the female member 2 facing the male member 1. The female fitting portion 24 has a concave shape corresponding to the shape of the male fitting portion 14. The bottom of the female fitting portion 24 is connected to the second refrigerant passage 23.

[0024] A seal washer 3 is disposed on the outer periphery of the male fitting portion 14. The portion of the surface of the male member 1 facing the female member 2 that surrounds the male fitting portion 14 forms a male seal surface 15 against which the seal washer 3 abuts. The portion of the surface of the female member 2 facing the male member 1 that surrounds the female fitting portion 24 forms a female seal surface 25 against which the seal washer 3 abuts. The male seal surface 15 and the female seal surface 25 face each other. The seal washer 3 will be described in detail later.

[0025] In principle, the central axes of the male fitting portion 14 and the female fitting portion 24 are aligned. The central axis directions of the male fitting portion 14 and the female fitting portion 24 are parallel to the outer peripheral surface of the male fitting portion 14 and the inner peripheral surface of the female fitting portion 24. The central axis directions of the male fitting portion 14 and the female fitting portion 24 are vertical in Figure 2. Note that, although the central axes of the male fitting portion 14 and the female fitting portion 24 are aligned in principle, they may become misaligned when fastened with the fastening bolt 5.

[0026] The male member 1 and the female member 2 move parallel to the central axis direction of the male fitting portion 14 and the female fitting portion 24, and the male fitting portion 14 is inserted into the female fitting portion 24. In other words, the direction in which the male member 1 and the female member 2 approach each other is parallel to the central axis direction of the male fitting portion 14 and the female fitting portion 24.

[0027] When the male fitting portion 14 is inserted into the female fitting portion 24, the male refrigerant pipe 11, the first refrigerant passage 13, the second refrigerant passage 23, and the female refrigerant pipe 21 are arranged in series with their central axes aligned. When the male fitting portion 14 is inserted into the female fitting portion 24, the male refrigerant pipe 11, the first refrigerant passage 13, the second refrigerant passage 23, and the female refrigerant pipe 21 are all in communication with each other.

[0028] The pressure difference between the refrigerant passages 13, 23 and the outside (atmospheric side) can be set as desired. In this embodiment, the refrigerant in the refrigerant passages 13, 23 is assumed to be at a pressure higher than atmospheric pressure. Therefore, the refrigerant pressure acts on the seal washer 3. In this specification, the refrigerant pressure is also referred to as the internal pressure.

[0029] The refrigerant passages 13, 23 can communicate with the outside (atmosphere) through the space between the male member 1 and the female member 2. A seal washer 3 is interposed between the male member 1 and the female member 2, and the seal washer 3 seals the space between the male member 1 and the female member 2.

[0030] The male member 1 is formed with a bolt insertion hole 16 into which the fastening bolt 5 is inserted. The female member 2 is formed with a female threaded portion 26 into which the fastening bolt 5 is screwed, at a position corresponding to the bolt insertion hole 16. The central axes of the fastening bolt 5, the bolt insertion hole 16, and the female threaded portion 26 are parallel to the central axes of the male fitting portion 14 and the female fitting portion 24.

[0031] The male member 1 and the female member 2 are fastened together by a single fastening bolt 5. When the fastening bolt 5 is tightened, the male member 1 and the female member 2 move in the direction of the central axis of the fastening bolt 5. The central axis of the fastening bolt 5 is located away from the central axis of the seal washer 3. For this reason, fastening by the fastening bolt 5 is a one-sided fastening in which the seal washer 3 sandwiched between the male fitting portion 14 and the female fitting portion 24 is tightened from only one side.

[0032] Next, the configuration of the seal washer 3 will be described using Figures 3 to 5. Figures 3 to 5 show the seal washer 3 in a free state where no external force is acting. In Figures 4 and 5, the up-down direction in the figures is the thickness direction of the seal washer 3, and the left-right direction in the figures is the radial direction of the seal washer 3. The thickness direction of the seal washer 3 can be said to be the direction of the central axis of the seal washer 3, and in principle, it coincides with the central axes of the male fitting portion 14 and the female fitting portion 24.

[0033] 3 to 5, the seal washer 3 includes an annular retainer 31 and an annular inner seal portion 32. The retainer 31 and the inner seal portion 32 do not overlap when viewed in the thickness direction.

[0034] The retainer 31 is an annular plate member that restrains and holds the inner seal portion 32. The retainer 31 has a plate surface that is perpendicular to the central axis. The retainer 31 is made of a material that is more rigid than the inner seal portion 32, such as a metal or a hard resin. In this embodiment, an aluminum alloy is used for the retainer 31.

[0035] The inner seal portion 32 is an annular elastic member provided at least on the inner circumferential side of the retainer 31. The inner seal portion 32 is thicker than the retainer 31.

[0036] The outer periphery of the inner seal portion 32 is joined to the inner periphery of the retainer 31. The outer periphery of the inner seal portion 32 is joined to the retainer 31 by at least one of mechanical adhesion, chemical adhesion, and welding.

[0037] The inner seal portion 32 is an elastic member, and any sealing material can be used. Examples of sealing materials that can be used for the inner seal portion 32 include rubber materials such as natural rubber, isoprene rubber, butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, styrene butadiene rubber, butyl rubber, ethylene propylene rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, chloroprene rubber, silicone rubber, fluorosilicone rubber, urethane rubber, hydrin rubber, epichlorohydrin rubber, fluororubber, perfluoroelastomer, and tetrafluoroethylene-propylene-based fluororubber, as well as thermoplastic elastomer materials such as polystyrene-based, polyolefin-based, polyurethane-based, and polyester-based.

[0038] The sealing material can be selected in accordance with the environment in which the seal washer 3 is used, taking into consideration heat resistance, cold resistance, oil resistance, gas permeability, and fluid resistance.

[0039] In terms of heat resistance, hydrogenated nitrile rubber, ethylene propylene rubber, butyl rubber, acrylic rubber, silicone rubber, fluorosilicone rubber, epichlorohydrin rubber, fluororubber, perfluoroelastomer, tetrafluoroethylene-propylene fluororubber, chlorosulfonated polyethylene rubber, and chlorinated polyethylene rubber have excellent heat resistance.

[0040] Natural rubber, isoprene rubber, silicone rubber, fluorosilicone rubber, butadiene rubber, ethylene propylene rubber, fluororubber, perfluoroelastomer, and tetrafluoroethylene-propylene fluororubber have excellent cold resistance, while nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, fluorosilicone rubber, urethane rubber, fluororubber, perfluoroelastomer, and tetrafluoroethylene-propylene fluororubber have excellent oil resistance.

[0041] Nitrile rubber, hydrogenated nitrile rubber, butyl rubber, hydrin rubber, epichlorohydrin rubber, chlorosulfonated polyethylene rubber, urethane rubber, chloroprene rubber, fluororubber, perfluoroelastomer, and tetrafluoroethylene-propylene fluororubber have excellent gas permeability resistance.

[0042] Alternatively, the seal material may be selected based on the material's resistance to the fluid used. Examples of seal materials highly resistant to engine oil include nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, and fluororubber. Examples of seal materials highly resistant to ATF (automatic transmission fluid) include nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, and fluororubber. Examples of seal materials highly resistant to brake oil include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, butyl rubber, chloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, and fluororubber. Examples of seal materials highly resistant to fuel oil include chlorosulfonated polyethylene rubber, urethane rubber, nitrile rubber, hydrogenated nitrile rubber, hydrin rubber, fluorosilicone rubber, and fluororubber.

[0043] Examples of sealing materials that are highly resistant to cooling water (coolant), water, hot water, or water vapor include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, butyl rubber, nitrile rubber, hydrogenated nitrile rubber, silicone rubber, fluorosilicone rubber, and fluororubber.

[0044] Examples of sealing materials that are highly resistant to organic acids include butyl rubber, silicone rubber, and fluororubber. Examples of sealing materials that are highly resistant to inorganic acids include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, butyl rubber, chloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, silicone rubber, fluorosilicone rubber, and fluororubber.

[0045] Examples of sealing materials that are highly resistant to alkali include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, butyl rubber, chloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, and fluororubber.

[0046] Examples of sealing materials that are highly resistant to fluorine-based gas refrigerants (and compressor oils) include ethylene propylene rubber, butyl rubber, chloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, and fluororubber. Examples of sealing materials that are highly resistant to natural refrigerants (and compressor oils) include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, ethylene propylene rubber, chloroprene rubber, silicone rubber, fluorosilicone rubber, acrylic rubber, and fluororubber. Examples of sealing materials that are highly resistant to hydrogen include ethylene propylene rubber, nitrile rubber, hydrogenated nitrile rubber, and fluororubber.

[0047] Furthermore, the resistance of a sealing material to a fluid used can be determined by its Hansen solubility parameter (HSP value). For example, when comparing the HSP values ​​when HFO-1234yf is used as the fluid and hydrogenated nitrile rubber (HNBR) and ethylene propylene rubber (EPDM) are used as sealing materials, HNBR has a Hansen solubility parameter (HSP value) that is farther apart than EPDM, making it less soluble. For this reason, HNBR has smaller volume change and gas permeability than EPDM, and can be considered to have superior performance as a sealing material.

[0048] Furthermore, when a resin material is used for the retainer 31 and a thermoplastic elastomer material is used as the seal material constituting the inner seal portion 32, the retainer 31 and the inner seal portion 32 can be joined by thermal welding. In this case, no adhesive is required to join the retainer 31 and the inner seal portion 32.

[0049] In this embodiment, hydrogenated nitrile rubber (HNBR) is used for the inner seal portion 32. HNBR is an elastic material that has excellent heat resistance, oil resistance, and gas permeability resistance.

[0050] Furthermore, it is desirable that the seal material used for the inner seal portion 32 has a hardness within a predetermined range. If the hardness of the seal material is low, the sealing performance will decrease. On the other hand, if the hardness of the seal material is high, the reaction force during fastening will increase, and the fastening force required for sealing will increase. For this reason, it is desirable that the seal material used for the inner seal portion 32 has a Shore A hardness within the range of 60 degrees to 90 degrees in order to achieve both sealing performance and low reaction force.

[0051] If the Shore A hardness of the sealing material is low, the elasticity decreases, and the sealing performance and durability decrease, so the Shore A hardness is preferably 60 degrees or more. The lower limit of the Shore A hardness of the sealing material can be determined based on the relationship between the refrigerant pressure (fluid pressure) and the maximum thickness portion 32c of the inner seal portion 32.

[0052] The seal washer 3 of this embodiment exhibits the same sealing effect as an O-ring when the compressibility is low. Therefore, the lower limit of the Shore A hardness of the seal material used for the inner seal portion 32 can be determined based on the magnitude relationship between the surface pressure (sealing pressure) of the O-ring and the fluid pressure.

[0053] It is known that the reaction force F of an O-ring when the compression ratio is low can be calculated using the following formula (1). Formula (1) is described in "Latest Sealing Technology: Understanding Sealing and Leakage and Troubleshooting (Authors: Akio Niuchi / Toshiyuki Sawa, Publisher: Techno System Co., Ltd., Publication Year: 2010)."

[0054] F [kgf] = 4.8 x 10 ―７ d １．２ (δ / d) １．３ H ４．５ L... (1) where d is the thickness of the O-ring [10-1 mm], δ is the compression allowance of the O-ring [mm], H is the Shore A hardness, and L is the circumference of the center diameter of the thickness part of the O-ring [10 ―１ mm].

[0055] The O-ring contact width that is recommended for an O-ring to have a compression rate of 8% is calculated by Pythagoras' theorem as follows: 2 x (r ２ -(92 / 100 x r) ２ ) １／２ ≒ 0.784 × r.

[0056] Here, the seal surface pressure P is the average surface pressure of the O-ring contact width at a compression rate of 8%, and is obtained by dividing the reaction force F by 0.784r and converting kgf to N using the following formula (2).

[0057] Seal surface pressure P = 6.25 x 10 ―８ d １．２ (δ / d) １．３ H ４．５ / r (2) If the seal surface pressure P calculated by formula (2) exceeds the fluid pressure, it can be considered that the lower limit of the Shore A hardness required for sealing is met. Note that if the Shore A hardness is less than 75 degrees, the gasket coefficient m value is 0.5 (JIS B 2206), and the fluid pressure is added to the seal surface pressure P, so the seal surface pressure P can be calculated by doubling formula (2). In other words, if formula (2) × 2 > fluid pressure, it can be considered that the lower limit of the Shore A hardness required for sealing is met.

[0058] Therefore, the desirable Shore A hardness of the sealing material is preferably 60 degrees or more from the viewpoint of rubber elasticity, or, in terms of the relationship with fluid pressure, it is desirable that the Shore A hardness be equal to or greater than a value that satisfies the following equation: (2) × 2 > fluid pressure.

[0059] Furthermore, if the Shore A hardness of the sealing material is high, the reaction force when fastening the male member 1 and female member 2 increases, and the fastening force required for sealing also increases. For this reason, it is desirable that the sealing material used for the inner seal portion 32 has a Shore A hardness of less than 90 degrees in order to achieve both sealing properties and low reaction force.

[0060] Furthermore, according to the gasket coefficient m value described in JIS B 8265 Appendix 3, if the Shore A hardness is less than 75 degrees, the seal surface pressure against the internal fluid pressure can be reduced. For this reason, it is more desirable to have a Shore A hardness of less than 75 degrees. In other words, in terms of the balance between sealing performance and the required fastening force, it is more desirable to have the Shore A hardness of the sealing material be less than 75 degrees.

[0061] Furthermore, since rubber has a hardness tolerance of about ±5 degrees due to manufacturing variations, it is most desirable for the seal material to have a Shore A hardness of 65 degrees or more and less than 75 degrees. In this embodiment, HNBR with a Shore A hardness of 70 degrees is used for the inner seal portion 32.

[0062] As shown in FIGS. 4 and 5, the inner seal portion 32 in a free state has a thick portion 32a and a connecting portion 32b.

[0063] The thick portion 32a is a main portion of the inner seal portion 32 and is thicker than the retainer 31. The thick portion 32a is a portion that abuts against the male seal surface 15 and the female seal surface 25 to provide a sealing function. In this embodiment, the thick portion 32a has a circular circumferential cross section perpendicular to the circumferential direction.

[0064] The connecting portion 32b connects the thick portion 32a and the retainer 31. The connecting portion 32b is a straight portion having a linear cross section in the circumferential direction, and has a thickness similar to that of the retainer 31. In principle, the connecting portion 32b is a portion that does not come into contact with the male seal surface 15 or the female seal surface 25 and does not exhibit a sealing function.

[0065] The thick portion 32a is disposed radially inwardly from the retainer 31 by the radial length of the connecting portion 32b. Therefore, when the thick portion 32a is deformed by compression between the male member 1 and the female member 2, the inner seal portion 32 can be prevented from deforming to a position where it overlaps with the retainer 31 and becoming caught in the retainer 31.

[0066] In this embodiment, the inner seal portion 32 has a circular circumferential cross section in the free state, and therefore the maximum thickness portion 32c corresponds to the center of the circle, and the center of gravity 32d is also the center of the circle. Therefore, in the free state, the maximum thickness portion 32c and the center of gravity 32d are located at the same position in the radial direction. The maximum thickness portion 32c of the inner seal portion 32 is the portion where the width of the inner seal portion 32 in the thickness direction is greatest in the free state.

[0067] The seal washer 3 is attached to the outer periphery of the male fitting portion 14. The inner diameter of the inner seal portion 32 in a free state is smaller than the outer diameter of the male fitting portion 14. Therefore, when the seal washer 3 is attached to the outer periphery of the male fitting portion 14, the inner seal portion 32 is subjected to a radial compressive force. The outer periphery of the male fitting portion 14 serves as a retaining surface that holds the seal washer 3 and prevents it from falling off.

[0068] Next, the configuration of the portion where the seal washer 3 is sandwiched between the male member 1 and the female member 2 will be described with reference to Figures 6 to 8. Figures 6 to 8 show an enlarged view of the portion surrounded by the circular dashed line in Figure 2, and show the portion where the seal washer 3 is sandwiched between the male member 1 and the female member 2.

[0069] Figure 6 shows the seal washer 3 sandwiched between the male member 1 and the female member 2, with the inner seal portion 32 compressed and deformed by the male member 1 and the female member 2. For ease of explanation, Figure 7 shows the seal washer 3 with a dashed line. Figure 8 shows the inner seal portion 32 in a free state where it is not compressed or deformed by the male member 1 and the female member 2.

[0070] 6 to 8, the up-down direction in the drawings corresponds to the thickness direction of the seal washer 3. In Figures 6 to 8, the left-right direction in the drawings corresponds to the radial direction of the seal washer 3, with the left side in the drawings being the radially outer side and the right side in the drawings being the radially inner side.

[0071] When the seal washer 3 is sandwiched between the male member 1 and the female member 2, the thickness direction of the seal washer 3 is parallel to the central axis direction of the male fitting portion 14 and the female fitting portion 24. When the seal washer 3 is sandwiched between the male member 1 and the female member 2, the refrigerant passes through the radially inner side of the seal washer 3.

[0072] The surface of the male member 1 facing the female member 2 has a stepped shape, and a gap A with a predetermined distance is formed around the male fitting portion 14 between the male seal surface 15 and the female seal surface 25. The seal washer 3 is placed in the gap A.

[0073] The seal washer 3 is disposed at the base of the male fitting portion 14 and is sandwiched between the male seal surface 15 and the female seal surface 25. The inner seal portion 32 is in close contact with the male seal surface 15 and the female seal surface 25, sealing the gap between the male seal surface 15 and the female seal surface 25 and isolating the refrigerant passages 13, 23 from the outside (atmosphere).

[0074] The male seal surface 15 is a plane perpendicular to the central axis of the male fitting portion 14. The female seal surface 25 includes a first female seal surface 25a and a second female seal surface 25b. The first female seal surface 25a is a plane perpendicular to the central axis of the female fitting portion 24. Therefore, when the male fitting portion 14 is inserted into the female fitting portion 24, the male seal surface 15 and the first female seal surface 25a are parallel to each other.

[0075] The second female seal surface 25b is a tapered surface that is inclined relative to the male seal surface 15 and the first female seal surface 25a, and the male seal surface 15 and the first female seal surface 25a are non-parallel seal surfaces that are not parallel to each other. The distance between the male seal surface 15 and the second female seal surface 25b is larger than the distance between the male seal surface 15 and the first female seal surface 25a.

[0076] The second female seal surface 25b is provided closer to the female fitting portion 24 than the first female seal surface 25a. The second female seal surface 25b can be formed by chamfering the annular corner formed by the connecting portion between the female seal surface 25 and the inner peripheral surface of the female fitting portion 24. In this embodiment, the second female seal surface 25b is formed at an angle of 15 to 30 degrees with respect to the inner peripheral surface of the female fitting portion 24.

[0077] The first female seal surface 25a and the second female seal surface 25b are formed continuously. The second female seal surface 25b is spaced apart from the male seal surface 15 gradually as it approaches the male fitting portion 14 and the female fitting portion 24, and the space between the second female seal surface 25b and the male seal surface 15 gradually increases toward the radially inward direction of the seal washer 3.

[0078] Here, the positional relationship between the gap A formed between the male seal surface 15 and the female seal surface 25 and the seal washer 3 will be described.

[0079] As shown in Fig. 7, the gap A includes a first gap A1 and a second gap A2. In Fig. 7, the first gap A1 is indicated by dashed hatching slanting upward to the right, and the second gap A2 is indicated by dashed hatching slanting upward to the left. The intersection of the first female seal surface 25a and the second female seal surface 25b forms the boundary between the first gap A1 and the second gap A2 in the radial direction.

[0080] The first gap A1 is located on the side farther from the male fitting portion 14 and the female fitting portion 24. The second gap A2 is located on the side closer to the male fitting portion 14 and the female fitting portion 24.

[0081] The first gap A1 is formed by arranging the male seal surface 15 and the first female seal surface 25a at a predetermined distance, and is the space sandwiched between the male seal surface 15 and the first female seal surface 25a. The second gap A2 is formed by arranging the male seal surface 15 and the second female seal surface 25b at a predetermined distance, and is the space sandwiched between the male seal surface 15 and the second female seal surface 25b. The closer the second gap A2 is to the male fitting portion 14 and the female fitting portion 24, the larger the distance between the male seal surface 15 and the second female seal surface 25b becomes.

[0082] In the first gap A1, the male seal surface 15 and the first female seal surface 25a are parallel. In the second gap A2, the male seal surface 15 and the second female seal surface 25b are not parallel, and the second female seal surface 25b is inclined relative to the male seal surface 15. In other words, the second female seal surface 25b constituting the second gap A2 is a tapered surface inclined relative to the male seal surface 15 and the first female seal surface 25a constituting the first gap A1.

[0083] In the second gap A2, the distance between the male seal surface 15 and the female seal surface 25 is wider than in the first gap A1. In other words, the distance between the male seal surface 15 and the second female seal surface 25b in the second gap A2 is larger than the distance between the male seal surface 15 and the first female seal surface 25a in the first gap A1. The first gap A1 can be considered a standard gap, and the second gap A2 can be considered an enlarged gap.

[0084] A seal washer 3 is disposed in a gap A between the male seal surface 15 and the female seal surface 25. A retainer 31 is disposed in the first gap A. The thickness of the retainer 31 is smaller than the distance between the male seal surface 15 and the first female seal surface 25a.

[0085] The inner seal portion 32 is disposed across the first gap A1 and the second gap A2. As shown in Fig. 8, the thickness of the maximum thickness portion 32c of the inner seal portion 32 is greater than the distance between the male seal surface 15 and the first female seal surface 25a. Furthermore, the thickness of the maximum thickness portion 32c of the inner seal portion 32 is greater than the distance between the male seal surface 15 and at least a portion of the second female seal surface 25b.

[0086] In a circumferential cross section of the inner seal portion 32, of the maximum thickness portion 32c and the center of gravity 32d of the inner seal portion 32, at least the one located radially inward of the inner seal portion 32 is located in the second gap A2. In the present embodiment, the maximum thickness portion 32c and the center of gravity 32d of the inner seal portion 32 are located in the same radial position, so both the maximum thickness portion 32c and the center of gravity 32d are located in the second gap A2. Furthermore, in a circumferential cross section of the inner seal portion 32, more than half of the cross-sectional area of ​​the thick portion 32a is located in the second gap A2.

[0087] In this embodiment, the filling rate of the inner seal portion 32 in the gap A is set to be within a predetermined range. The filling rate is a numerical value expressed as a percentage of the volume of the inner seal portion 32 relative to the volume of the portion of the gap A where the inner seal portion 32 can deform. The portion of the gap A where the inner seal portion 32 can deform is a portion located radially inward of the seal washer 3 relative to the boundary between the retainer 31 and the inner seal portion 32 in the gap A. In FIG. 8 , the portion of the gap A where the inner seal portion 32 can deform is the portion indicated by dashed hatching slanting upward to the right. To calculate the filling rate, the circumferential cross-sectional areas of the inner seal portion 32 and the gap A may be used instead of the volumes of the inner seal portion 32 and the gap A.

[0088] Increasing the filling rate of the inner seal portion 32 improves the sealing performance of the inner seal portion 32, while decreasing the filling rate of the inner seal portion 32 reduces the tightening torque of the fastening bolt 5 that fastens the male member 1 and the female member 2, thereby reducing the bolt axial force. On the other hand, if the filling rate is too low, the sealing performance decreases, and if the filling rate is too high, the reaction force increases, requiring a large fastening force. For this reason, in this embodiment, the filling rate of the inner seal portion 32 in the gap portion A is set to 70% or more and less than 100%.

[0089] Next, the pressing of the seal washer 3 by the male member 1 and female member 2 when the male member 1 and female member 2 are fastened together with the fastening bolt 5 will be described with reference to Figures 9 and 10. The upper part of Figure 10 shows a state in which the male member 1 and female member 2 are not pressing against the seal washer 3, and the lower part of Figure 10 shows a state in which the male member 1 and female member 2 are pressing against the seal washer 3.

[0090] As shown in Figure 9, before fastening the male member 1 and female member 2, the seal washer 3 is assembled to the base of the male mating portion 14 so that it contacts the male seal surface 15. The male seal surface 15 is the seating surface of the seal washer 3, and the female seal surface 25 is the opposite surface to the seating surface. Because the inner seal portion 32 receives a compressive force from the outer peripheral surface of the male mating portion 14, the contact area of ​​the inner seal portion 32 with the outer peripheral surface of the male mating portion 14 deforms toward the male seal surface 15 and the female seal surface 25.

[0091] Next, the male member 1 and the female member 2 are fastened together with the fastening bolt 5, causing the male member 1 and the female member 2 to move closer to each other. As a result, the male fitting portion 14 is inserted into the female fitting portion 24.

[0092] As shown in the upper part of Figure 10, when the male member 1 and the female member 2 move in a direction approaching each other, the inner seal portion 32 is pressed by the male side seal surface 15 and the female side seal surface 25 and receives a compressive force.

[0093] As shown in the lower part of Figure 10, the inner seal portion 32 is deformed by the pressure from the male seal surface 15 and the female seal surface 25. The deformed inner seal portion 32 comes into close contact with the outer peripheral surfaces of the male seal surface 15, the female seal surface 25, and the male fitting portion 14. As a result, the inner seal portion 32 seals between the male seal surface 15 and the female seal surface 25.

[0094] Since the maximum thickness portion 32c of the inner seal portion 32 is located at a position corresponding to the second female seal surface 25b, it is possible to reduce the tightening torque when fastening the male member 1 and the female member 2 with the fastening bolt 5. This point will be explained below.

[0095] The inner seal portion 32 receives compressive forces from the male seal surface 15, the female seal surface 25, and the outer peripheral surface of the male fitting portion 14. As a result, surface pressure is generated at the contact point between the inner seal portion 32 and the male seal surface 15, the contact point between the inner seal portion 32 and the female seal surface 25, and the contact point between the inner seal portion 32 and the outer peripheral surface of the male fitting portion 14.

[0096] 9, arrows indicate the force vectors acting on the inner seal portion 32 from the male seal surface 15, the female seal surface 25, and the male fitting portion 14. The force vectors acting on the inner seal portion 32 from the male seal surface 15, the female seal surface 25, and the outer peripheral surface of the male fitting portion 14 are all different.

[0097] The inner seal portion 32 is pressed in the thickness direction by the male seal surface 15. As a result, the contact portion of the inner seal portion 32 with the male seal surface 15 is deformed toward the female seal surface 25 and the retainer 31.

[0098] The inner seal portion 32 is pressed in the thickness direction by the first female seal surface 25 a and in a direction non-parallel to the thickness direction by the second female seal surface 25 b. In other words, the force that the inner seal portion 32 receives from the female seal surface 25 is dispersed in the thickness direction and in a direction different from the thickness direction.

[0099] The contact portion of the inner seal portion 32 with the female seal surface 25 comes into contact with the corner formed by the first female seal surface 25a and the second female seal surface 25b, and deforms toward the retainer 31 and the back of the second gap A2. In the second gap A2, the distance between the male seal surface 15 and the female seal surface 25 increases toward the radially inward side of the inner seal portion 32. As a result, the inner seal portion 32 deforms more toward the back of the second gap A2, and can deform to enter the back space of the second gap A2 with a low reaction force.

[0100] In this embodiment, the refrigerant pressure in the refrigerant passages 13, 23 is higher than atmospheric pressure, so internal pressure acts on the seal washer 3 from the refrigerant passages 13, 23 side. The upper part of Fig. 11 shows the state before the internal pressure acts on the seal washer 3, and the lower part of Fig. 11 shows the state after the internal pressure acts on the seal washer 3.

[0101] As shown by the arrows in the upper part of Fig. 11, internal pressure is applied to the inner seal portion 32 from the refrigerant passages 13, 23 side. The lower part of Fig. 11 shows an example in which the inner seal portion 32 is deformed in the direction shown by the arrows in the lower part of Fig. 11 due to the application of internal pressure.

[0102] The direction of deformation of the inner seal portion 32 due to the application of internal pressure is a direction diagonally upward to the left in Figure 11, and the inner seal portion 32 deforms in a direction that wraps around the corner formed by the first female side seal surface 25a and the second female side seal surface 25b.

[0103] When the inner seal portion 32 is deformed by the application of internal pressure, the retainer 31 tends to approach either the male seal surface 15 or the female seal surface 25. In the example shown in the lower part of Figure 11, the retainer 31 is shown in a state where it is biased toward the female seal surface 25.

[0104] The lower part of Figure 11 shows an example in which the application of internal pressure causes the inner seal portion 32 to deform so as to get into the gap between the upper seal surface 15 and the retainer 31, but there are also cases in which the application of internal pressure causes the inner seal portion 32 to deform so as to get into the gap between the upper seal surface 15 and the retainer 31. In this case, the retainer 31 becomes biased toward the male seal surface 15.

[0105] When internal pressure is applied to the inner seal portion 32, it deforms so as to be pressed against the outer peripheral surfaces of the male seal surface 15, the female seal surface 25, and the male fitting portion 14. The direction of deformation of the inner seal portion 32 is the direction in which it approaches the male seal surface 15, and the inner seal portion 32 is pressed strongly against the male seal surface 15, which tends to increase the surface pressure between the inner seal portion 32 and the male seal surface 15.

[0106] On the other hand, because the deformation direction of the inner seal portion 32 is not a direction toward the female seal surface 25, the surface pressure between the inner seal portion 32 and the female seal surface 25 is unlikely to increase. In contrast, in this embodiment, the contact area between the inner seal portion 32 and the female seal surface 25 is smaller than the contact area between the inner seal portion 32 and the male seal surface 15, and stress is likely to be concentrated by being pressed against the corners. This increases the effect of increasing the surface pressure between the inner seal portion 32 and the female seal surface 25.

[0107] When internal pressure is applied to the inner seal portion 32, the surface pressure between the inner seal portion 32 and the male seal surface 15, the surface pressure between the inner seal portion 32 and the female seal surface 25, and the surface pressure between the inner seal portion 32 and the outer peripheral surface of the male fitting portion 14 all increase. Even if the surface pressure between the inner seal portion 32 and each contact surface is lower than the internal pressure before the application of internal pressure, the application of internal pressure increases each surface pressure, and the surface pressure between the inner seal portion 32 and each contact surface exceeds the internal pressure. As a result, the sealing performance can be improved.

[0108] Therefore, even if the fastening force of the fastening bolt 5 is small and the compressive force on the inner seal portion 32 by the male member 1 and the female member 2 is low, the internal pressure acting on the inner seal portion 32 can improve the sealing property of the inner seal portion 32.

[0109] Figure 12 shows the results of measuring the reaction force during assembly of the seal washer 3 of the first embodiment. In Figure 12, the seal washer described in JP 2018-48653 A is used as a comparative example. In the seal washer of the comparative example, the thickest part of the inner seal portion 32 is located in the first gap A1 where the male seal surface 15 and the female seal surface 25 are arranged parallel to each other with a predetermined gap between them. Furthermore, in the seal washer of the comparative example, the connecting portion 32b is not provided in the inner seal portion 32, and the retainer 31 and the inner seal portion 32 partially overlap when viewed in the thickness direction.

[0110] 12 shows the results of measuring the reaction force with a load cell when a rubber material equivalent to JIS B2401 HNBR-70 is used for the inner seal portion 32 in both the first embodiment and the comparative example, and the filling rates are set to 70%, 80%, and 90%. The reaction force on the vertical axis of FIG. 12 is expressed as a percentage, with the reaction force of the comparative example with a filling rate of 90% being set to 1.

[0111] 12, the first embodiment can reduce the reaction force significantly more than the comparative example at any of the filling rates of 70%, 80%, and 90%. In particular, the higher the filling rate, the more effective the first embodiment is at reducing the reaction force.

[0112] Figure 13 shows the results of a high-temperature storage test (leak test) conducted on the seal washers of the first embodiment and the comparative example. The comparative example, like Figure 12, used the seal washer described in JP 2018-48653 A. For both the first embodiment and the comparative example, samples were prepared of fastened bodies that were fastened using M6 bolts with a strength classification of 8.8 with a tightening torque of 8 N m and had filling rates of 70% and 90%.

[0113] A high-temperature storage test at 150°C was conducted using the fasteners of the first embodiment and the comparative example (n = 3). The high-temperature storage test was continued every 24 hours until a leak occurred in one sample using a water immersion inspection device. The water immersion inspection device applied a pressure of 3.53 MPa.

[0114] As shown in Figure 13, in the comparative example, leakage occurred after 48 hours at a filling rate of 70%, and after 72 hours at a filling rate of 90%. In contrast, in the first embodiment, leakage occurred once after 120 hours at a filling rate of 70%, and no leakage occurred for the remaining 120 hours, so the high-temperature storage test was discontinued. According to the configuration of the first embodiment, the sealing performance in the high-temperature storage test was significantly improved.

[0115] In the present embodiment described above, at least the maximum thickness portion 32c and the center of gravity 32d of the inner seal portion 32 of the seal washer 3, whichever is located radially inward, are disposed in the second gap A2. As a result, the inner seal portion 32 enters the second gap A2 when the first member 1 and the second member 2 are fastened together, thereby reducing the amount of deformation and enabling deformation with a low reaction force. This allows for a reduction in the tightening torque when fastening the male member 1 and the female member 2 with the fastening bolt 5, ensuring sufficient sealing performance with a small axial force.

[0116] Furthermore, in the seal washer 3 of this embodiment, the retainer 31 and the inner seal portion 32 do not overlap when viewed in the thickness direction. Therefore, when the inner seal portion 32 is compressed by the male member 1 and the female member 2, the retainer 31 is not sandwiched between the inner seal portion 32, and therefore the tightening torque when the male member 1 and the female member 2 are fastened together with the fastening bolt 5 can be reduced.

[0117] Furthermore, in the seal washer 3 of this embodiment, the contact area between the inner seal portion 32 and the female seal surface 25 is small, and stress is likely to be concentrated by being pressed at the corners, so that the surface pressure between the inner seal portion 32 and the female seal surface 25 is likely to increase when internal pressure is applied. Therefore, the surface pressure between the inner seal portion 32 and the female seal surface 25, against which the inner seal portion 32 is less likely to be pressed when internal pressure is applied, can be effectively increased, thereby improving sealing performance.

[0118] Furthermore, in this embodiment, since the tightening torque of the fastening bolt 5 can be reduced, the male member 1 and the female member 2 can be reliably fastened together even in a configuration in which one-sided fastening is performed using the fastening bolt 5. This makes it less likely for the fastening to occur at an angle, and it is possible to prevent insufficient sealing and damage to the fastening bolt 5. Furthermore, it is possible to prevent a decrease in sealing performance due to deterioration of the inner seal portion 32 and the intrusion of impurities into the gap between the male member 1 and the female member 2.

[0119] Furthermore, in this embodiment, by disposing at least the maximum thickness portion 32c and the center of gravity 32d of the inner seal portion 32 of the seal washer 3, whichever is located radially inward, in the second gap A2, the distance from the central axis of the fastening bolt 5 to the thick portion 32a of the inner seal portion 32 (i.e., the seal diameter) is reduced. This reduces the internal pressure thrust acting on the male member 1 and the female member 2 when internal pressure is applied to the inner seal portion 32. As a result, elongation of the fastening bolt 5 and warping of the male member 1 when internal pressure is applied to the inner seal portion 32 are reduced, and the life of the seal washer 3 can be extended.

[0120] Furthermore, by using the inner seal portion 32 at a low compression ratio, it is possible to reduce the internal stress of the inner seal portion 32 and reduce the distortion that occurs in the inner seal portion 32. Therefore, even when the seal washer 3 is used for a long period of time, the amount of settling of the inner seal portion 32 is reduced, and the seal washer 3 can have a longer life.

[0121] Furthermore, the reduction in the tightening torque allows the size of the fastening bolt 5 to be reduced, thereby reducing the size of the pipe joint 100 and improving mountability on a vehicle. Furthermore, the reduction in the size of the fastening bolt 5 also allows for cost reduction.

[0122] Furthermore, because the inner seal portion 32 deforms to penetrate into the depth of the second gap A2, the contact area between the inner seal portion 32 and the female seal surface 25 can be increased, and the contact area between the inner seal portion 32 and the outer peripheral surface of the male fitting portion 14 can be increased. Furthermore, by the inner seal portion 32 deforming to penetrate into the depth of the second gap A2, the gas permeation distance can be increased. This makes it possible to suppress surface leakage from the contact surfaces between the inner seal portion 32 and the male seal surface 15 and female seal surface 25, as well as permeation leakage within the inner seal portion 32, thereby improving the sealing performance of the inner seal portion 32.

[0123] In this embodiment, the circumferential cross section of the inner seal portion 32 is circular. Such an inner seal portion 32 with a circular cross section is easy to manufacture and reduces dimensional variation. Furthermore, the seal washer 3 having the inner seal portion 32 with a circular cross section has a symmetrical shape in the thickness direction, eliminating assembly errors when assembling the seal washer 3 to the outer periphery of the male fitting portion 14. Furthermore, the inner seal portion 32 with a circular cross section has uniform and minimal stress distribution during deformation. This facilitates deformation deep into the second gap A2, thereby lengthening the gas permeation distance.

[0124] Second Embodiment Next, a second embodiment of the present disclosure will be described. In the second embodiment, only the parts that are different from the first embodiment will be described.

[0125] 14 to 18, the seal washer 3 of the second embodiment includes an outer seal portion 33. The outer seal portion 33 is provided radially outward of the inner seal portion 32.

[0126] The outer seal portion 33 is disposed closer to the outside than the inner seal portion 32. The outer seal portion 33 functions as a waterproof portion that prevents foreign matter such as water from entering the refrigerant passages 13, 23 from the outside.

[0127] In the second embodiment, because the refrigerant pressure in the refrigerant passages 13, 23 is higher than the external atmospheric pressure, a lower pressure acts on the outer seal portion 33 than on the inner seal portion 32. Therefore, the outer seal portion 33 can have lower sealing performance than the inner seal portion 32. In other words, the inner seal portion 32 can be positioned as a main seal portion, and the outer seal portion 33 can be positioned as a sub-seal portion.

[0128] The outer seal portions 33 are in contact with the plate surface of the retainer 31 and are provided on both sides of the plate surface of the retainer 31. The outer seal portions 33 are shaped symmetrically across the retainer 31. The outer seal portions 33 are provided so as to overlap the retainer 31 when viewed in the thickness direction.

[0129] In the second embodiment, the inner seal portion 32 and the outer seal portion 33 are integrated and made of the same material. As shown in Fig. 15, the maximum thickness portion 33a of the outer seal portion 33 in a free state is smaller than the maximum thickness portion 32c of the inner seal portion 32. The circumferential cross-sectional area of ​​the outer seal portion 33 is smaller than the circumferential cross-sectional area of ​​the inner seal portion 32.

[0130] Here, a description will be given of a circumferential cross section of the outer seal portion 33 on one surface side of the retainer 31. Hereinafter, the "circumferential cross section of the outer seal portion 33 on one surface side of the retainer 31" will be simply referred to as the "circumferential cross section of the outer seal portion 33."

[0131] 15 and 16 , the circumferential cross section of the outer seal portion 33 in a free state is a triangle with a base that contacts the plate surface of the retainer 31. More specifically, the circumferential cross section of the outer seal portion 33 is a right triangle with a base that contacts the plate surface of the retainer 31, a side that is perpendicular to the plate surface of the retainer 31, and a hypotenuse that is inclined relative to the plate surface of the retainer 31. In the circumferential cross section of the outer seal portion 33 of the retainer 31, the side that is perpendicular to the plate surface of the retainer 31 is located radially outward.

[0132] An acute angle is formed in the circumferential cross section of the outer seal portion 33, protruding from the plate surface of the retainer 31. The acute angle protruding from the plate surface of the retainer 31 is formed by two sides connected to the base that contacts the plate surface of the retainer 31. In other words, in the free state, the outer seal portion 33 has an acute angle at which the tip portion in the thickness direction of the maximum thickness portion 33a protrudes from the plate surface of the retainer 31. The tip portion of the acute angle protruding from the plate surface of the retainer 31 may be chamfered.

[0133] 17, the outer seal portion 33 is disposed in a first gap A1 formed between the male seal surface 15 and the first female seal surface 25a. The maximum thickness portion 33a of the outer seal portion 33 in the free state is greater than the distance between the male seal surface 15 and the first female seal surface 25a. Therefore, the outer seal portion 33 receives a compressive force from the male seal surface 15 and the first female seal surface 25a.

[0134] In the second embodiment, the filling rate of the outer seal portion 33 in the gap A is set to be within a predetermined range. The filling rate is a numerical value expressed as a percentage of the volume of the outer seal portion 33 relative to the volume of the portion of the gap A where the outer seal portion 33 can deform. The portion of the gap A where the outer seal portion 33 can deform is the portion where the retainer 31 and the outer seal portion 33 overlap when viewed in the thickness direction of the gap A.

[0135] 17 , the deformable portion of the outer seal portion 33 in the gap A is indicated by the dashed hatching that slopes upward to the left. To calculate the filling rate, the circumferential cross-sectional areas of the outer seal portion 33 and the gap A may be used instead of the volumes of the outer seal portion 33 and the gap A.

[0136] Increasing the filling rate of the outer seal portion 33 improves the sealing performance of the outer seal portion 33, while decreasing the filling rate of the outer seal portion 33 reduces the tightening torque between the male member 1 and the female member 2. On the other hand, if the filling rate is too low, the sealing performance decreases, and if the filling rate is too high, the reaction force increases, requiring a large tightening force. For this reason, in the second embodiment, the filling rate of the outer seal portion 33 in the gap A is set to 70% or more and less than 100%.

[0137] Next, a case where the seal washer 3 of this second embodiment is pressed by the male member 1 and the female member 2 will be described with reference to Fig. 18. The upper part of Fig. 18 shows a state where the male member 1 and the female member 2 are not pressing the seal washer 3, and the lower part of Fig. 18 shows a state where the male member 1 and the female member 2 are pressing the seal washer 3.

[0138] In this second embodiment, when the male member 1 and the female member 2 move in a direction approaching each other, the inner seal portion 32 and the outer seal portion 33 are pressed by the male side seal surface 15 and the female side seal surface 25 and are subjected to a compressive force.

[0139] As shown in the lower part of Figure 18, the inner seal portion 32 and the outer seal portion 33 are deformed by the pressure from the male seal surface 15 and the female seal surface 25. The deformed inner seal portion 32 and outer seal portion 33 come into close contact with the male seal surface 15 and the female seal surface 25. As a result, the gap between the male seal surface 15 and the female seal surface 25 is sealed by the inner seal portion 32 and the outer seal portion 33.

[0140] The upper part of FIG. 19 shows the state before internal pressure acts on the seal washer 3 of the second embodiment, and the lower part of FIG. 19 shows the state after internal pressure acts on the seal washer 3.

[0141] As shown in the upper part of Fig. 19, in the seal washer 3 of the second embodiment, as in the first embodiment, internal pressure is applied to the inner seal portion 32. The lower part of Fig. 19 shows an example in which the inner seal portion 32 is deformed in the direction indicated by the arrow in the lower part of Fig. 19 due to the application of internal pressure.

[0142] The seal washer 3 of the second embodiment has outer seal portions 33 on both sides of the retainer 31. The outer seal portions 33 are in close contact with the male seal surface 15 and the female seal surface 25, restricting movement of the retainer 31. Therefore, as shown in the lower part of Figure 19, even when internal pressure is applied to the inner seal portion 32, the retainer 31 is prevented from shifting toward either the male seal surface 15 or the female seal surface 25. This stabilizes the position of the retainer 31 in the gap A, making it easier for the inner seal portion 32 to deform toward the male seal surface 15 and the female seal surface 25. As a result, the surface pressure between the inner seal portion 32 and the female seal surface 25 can be effectively increased, improving sealing performance.

[0143] In the second embodiment described above, the female seal surfaces 25 are sealed by the outer seal portion 33 in addition to the inner seal portion 32. The outer seal portion 33 is provided radially outward of the inner seal portion 32, and can prevent foreign matter from entering the internal refrigerant passages 13, 23 from the outside.

[0144] Furthermore, in the free state, the tip of the maximum thickness portion 33a of the outer seal portion 33 is acute-angled, and therefore the outer seal portion 33 is easily deformed when pressed against the male seal surface 15 and the female seal surface 25. This allows the tightening torque of the fastening bolt 5 required to press the outer seal portion 33 to be reduced.

[0145] Furthermore, the maximum thickness portion 33a of the outer seal portion 33 is thinner than the maximum thickness portion 32c of the inner seal portion 32. This also reduces the tightening torque of the fastening bolt 5 required to press the outer seal portion 33.

[0146] Furthermore, the outer seal portion 33 has a shape that is symmetrical in the thickness direction, which makes it possible to eliminate assembly errors when assembling the seal washer 3 to the outer periphery of the male fitting portion 14.

[0147] In addition, in this second embodiment, by providing outer seal portions 33 on both sides of the retainer 31, the position of the retainer 31 can be stabilized when internal pressure is applied to the seal washer 3, thereby improving sealing performance.

[0148] Third Embodiment Next, a third embodiment of the present disclosure will be described. In this second embodiment, only the parts that are different from the above-described embodiments will be described.

[0149] 20, the pipe joint 100 of the third embodiment is provided with an O-ring 4. The O-ring 4 is interposed between the male fitting portion 14 and the female fitting portion 24.

[0150] A groove 14a into which the O-ring 4 is inserted is formed on the outer peripheral side surface of the male fitting portion 14. The groove 14a is formed between the tip and base of the male fitting portion 14.

[0151] The O-ring 4 is an elastic member, and can be made of any of the sealing materials of the inner seal portion 32 of the seal washer 3 exemplified in the first embodiment above. The O-ring 4 may be made of the same sealing material as the inner seal portion 32 and the outer seal portion 33 of the seal washer 3, or a different sealing material may be used.

[0152] In the third embodiment, hydrogenated nitrile rubber (HNBR) is used for the inner seal portion 32 and the outer seal portion 33 of the seal washer 3, and ethylene propylene rubber (EPDM) is used for the O-ring 4. EPDM has better cold resistance than HNBR. HNBR also has better gas permeability than EPDM.

[0153] The radial dimension of the O-ring 4 is larger than the depth dimension of the groove 14a. The difference between the radial dimension of the O-ring 4 and the depth dimension of the groove 14a is the compression allowance of the O-ring 4. The radial direction of the O-ring 4 is the left-right direction in Figure 20.

[0154] The O-ring 4 is compressed by the outer peripheral surface of the male fitting portion 14 and the inner peripheral surface of the female fitting portion 24. The O-ring 4 is in close contact with the outer peripheral surface of the male fitting portion 14 and the inner peripheral surface of the female fitting portion 24, sealing the gap between the male fitting portion 14 and the female fitting portion 24 and isolating the refrigerant passages 13, 23 from the outside (atmosphere).

[0155] The O-ring 4 is disposed closer to the refrigerant passages 13 and 23 than the seal washer 3. Therefore, the internal pressure acting on the O-ring 4 is higher than the internal pressure acting on the seal washer 3.

[0156] The internal pressure acting on the seal washer 3 due to the refrigerant that has permeated the O-ring 4 is an intermediate pressure that is lower than the refrigerant pressure in the refrigerant passages 13 and 23 and higher than the external atmospheric pressure. In this embodiment, the EPDM used for the O-ring 4 has a higher refrigerant permeability than the HNBR used for the inner seal portion 32 of the seal washer 3, so the intermediate pressure acting on the inner seal portion 32 is relatively high.

[0157] As shown in Figure 21, the pipe fitting 100 of this third embodiment fastens the male member 1 and the female member 2 with the seal washer 3 assembled to the base of the male fitting portion 14 and the O-ring 4 assembled in the groove portion 14a of the male fitting portion 14.

[0158] When the male fitting portion 14 is inserted into the female fitting portion 24, the O-ring 4 abuts against the second female seal surface 25b. The second female seal surface 25b functions as a guide surface that abuts against the O-ring 4 when the male fitting portion 14 with the O-ring 4 attached is inserted into the female fitting portion 24, thereby allowing the male fitting portion 14 to be smoothly inserted into the female fitting portion 24. Therefore, damage to the O-ring 4 when the male fitting portion 14 is inserted into the female fitting portion 24 can be prevented.

[0159] Fig. 22 shows the measurement results of the low-temperature sealing property and refrigerant gas permeation rate of the pipe fitting 100 of the third embodiment. In Fig. 22, pipe fittings provided with an O-ring 4 but not a seal washer 3 are designated as Comparative Examples 1 and 2. In Comparative Example 1, EPDM is used as the O-ring 4, and in Comparative Example 2, HMBR is used as the O-ring 4.

[0160] For the evaluation of low-temperature sealing properties, samples of fastened bodies were prepared for each of the third embodiment, Comparative Example 1, and Comparative Example 2, using M8 bolts to fasten with a tightening torque of 16 N m. Next, each sample was placed in a negative pressure state using a vacuum pump, and subjected to 24 cycles of cycling between -40°C and room temperature using a thermal shock tester. Samples that maintained negative pressure were evaluated as "no leaks," and samples whose internal pressure rose from negative pressure were evaluated as "leaks."

[0161] As shown in Figure 22, the third embodiment and comparative example 2 maintained negative pressure without leakage. In contrast, comparative example 1 experienced leakage and the pressure rose to atmospheric pressure after the test. The third embodiment and comparative example 2 used EPDM for the O-ring 4, while comparative example 1 used HNBR for the O-ring 4. In other words, using EPDM, which has excellent cold resistance, as the sealing material can improve low-temperature sealing performance.

[0162] The refrigerant gas permeation rate was measured using samples of the same configuration as those used to evaluate low-temperature sealing. HFO-1234yf was charged as the refrigerant gas in an amount sufficient to contain both gas and liquid phases, and the refrigerant gas permeation rate of each sample was measured using a gas permeability measuring device at an ambient temperature of 40°C.

[0163] In Fig. 22, the refrigerant gas permeation rate is expressed as an index, with the refrigerant gas permeation rate per unit time for Comparative Example 1 being set to 1. As shown in Fig. 22, the refrigerant gas permeation rate for each sample was 0.11 for the third embodiment, 1 for Comparative Example 1, and 0.30 for Comparative Example 2. Comparative Example 2, which uses an O-ring 4 made of HNBR, which has excellent gas permeability resistance, was able to reduce the refrigerant gas permeation rate more than Comparative Example 1, which used an O-ring 4 made of EPDM. Furthermore, the third embodiment, which combines an EPDM O-ring 4 with an HNBR seal washer 3, was able to significantly reduce the refrigerant gas permeation rate.

[0164] According to the third embodiment described above, the O-ring 4 is provided closer to the refrigerant passages 13, 23 than the seal washer 3. Therefore, the gap between the male member 1 and the female member 2 is sealed not only by the seal washer 3 but also by the O-ring 4, thereby more reliably sealing the gap between the male member 1 and the female member 2.

[0165] Furthermore, when the male fitting portion 14 is inserted into the female fitting portion 24, the O-ring 4 abuts against the second female seal surface 25b, so the male fitting portion 14, which has the O-ring 4 provided on its outer peripheral surface, can be smoothly inserted into the female fitting portion 24. This prevents the O-ring 4 from being damaged when the male fitting portion 14 is inserted into the female fitting portion 24.

[0166] Furthermore, in a configuration in which the O-ring 4 is provided in the male fitting portion 14, the tapered surface provided at the entrance of the female fitting portion 24 can be used as the second female seal surface 25b. In other words, by utilizing the tapered surface provided for the O-ring 4, it is possible to reduce the reaction force of the inner seal portion 32 when the inner seal portion 32 formed by the male member 1 and the female member 2 is compressed.

[0167] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows without departing from the spirit of the present disclosure. Furthermore, the means disclosed in the above-described embodiments may be combined as appropriate within the scope of feasibility.

[0168] For example, in each of the above embodiments, an example was described in which a tapered surface that widens the gap between the male seal surface 15 and the female seal surface 25 is provided on the female seal surface 25, but the tapered surface may be provided on at least one of the male seal surface 15 and the female seal surface 25. In other words, the tapered surface may be provided only on the male seal surface 15, or on both the male seal surface 15 and the female seal surface 25.

[0169] In addition, in each of the above embodiments, an example has been described in which the second female seal surface 25b constituting the second gap A2 is a tapered surface inclined relative to the male seal surface 15, but the second female seal surface 25b may have a configuration other than a tapered surface. The second female seal surface 25b only needs to have a larger gap between it and the male seal surface 15 than the first female seal surface 25a, and for example, the second female seal surface 25b may be stepped.

[0170] In addition, in the above-described embodiments, an example was described in which the circumferential cross section of the thick portion 32a of the inner seal portion 32 is circular, but the circumferential cross section of the thick portion 32a may be a shape other than circular. Figures 23 to 27 show specific examples of the inner seal portion 32 having different cross-sectional shapes of the thick portion 32a. Examples of cross-sectional shapes of the thick portion 32a include a rectangle as shown in Figure 23, a diamond as shown in Figure 24, an ellipse as shown in Figure 25, a combination of two ellipses as shown in Figure 26, and a combination of two rectangles as shown in Figure 27.

[0171] Furthermore, in the second embodiment, an example has been described in which the circumferential cross section of the outer seal portion 33 is a right triangle, but it may be a triangle other than a right triangle.

[0172] Furthermore, in the circumferential cross section of the outer seal portion 33 described in the second embodiment, at least one of the two sides forming an acute angle protruding from the plate surface of the retainer 31 may be curved inwardly and concavely. For example, Fig. 28 shows an example in which the oblique side is concave, Fig. 29 shows an example in which the side perpendicular to the plate surface of the retainer 31 is concave, and Fig. 30 shows an example in which both the oblique side and the side perpendicular to the plate surface of the retainer 31 are concave.

[0173] This reduces the acute angle protruding from the plate surface of the retainer 31, making the outer seal portion 33 more likely to deform when pressed between the male seal surface 15 and the female seal surface 25. This reduces the tightening torque of the fastening bolt 5 required to press the outer seal portion 33.

[0174] Furthermore, in each of the above embodiments, an example has been described in which the seal structure of the present disclosure is used in a pipe fitting 100 in which a male member 1 and a female member 2 are fastened together with a fastening bolt 5, but the seal structure of the present disclosure can also be applied to different configurations.

[0175] For example, the seal structure of the present disclosure can be used in the screw-type mounting structure shown in Fig. 31. The screw-type mounting structure shown in Fig. 31 does not include a fastening bolt 5, and the male member 1 and female member 2 are provided with a fastening structure. Note that the internal structure of the male member 1 is not shown in Fig. 31.

[0176] The female member 2 can be, for example, a wall portion of a pipe having a fluid flow path 28 therein. Figure 31 shows a portion of the pipe that constitutes the female member 2. The male member 1 can be, for example, a pressure sensor that detects the pressure in the fluid flow path 28. By inserting the male fitting portion 14 into the female fitting portion 24 formed as a through-hole in the female member 2, the detection portion provided at the tip of the male member 1 is positioned in the fluid flow path 28 of the female member 2.

[0177] A male thread is formed on the outer peripheral surface of the male fitting portion 14, and a female thread is formed on the inner peripheral surface of the female fitting portion 24. By rotating and screwing the male fitting portion 14 into the female fitting portion 24, the male member 1 and the female member 2 can be fastened together.

[0178] Even when the seal structure of the present disclosure is applied to the screw-type mounting structure shown in Fig. 31 , the same effect as in the first embodiment can be obtained, and the tightening torque of the male member 1 and the female member 2 can be reduced. In the configuration shown in Fig. 31 , when an outer seal portion 33 is provided on the seal washer 3, the same effect as in the second embodiment can be obtained.

[0179] The features of the seal structure disclosed in this specification are as follows: (Item 1) A seal structure comprising: a first member (1) having a male seal surface (15) and a male fitting portion (14) formed on the male seal surface so as to protrude from the male seal surface; a second member (2) having a female seal surface (25) facing the male seal surface and a female fitting portion (24) formed on the female seal surface so that the male fitting portion can be inserted; and a seal washer (3) having an annular retainer (31) and an annular inner seal portion (32) provided on the inner periphery of the retainer, and sandwiched between the male seal surface and the female seal surface while being disposed on the outer periphery of the male fitting portion, wherein the first member and the second member are fastened together so as to come close to each other and compress the inner seal portion at the male seal surface and the female seal surface, and the inner seal portion tightly contacts and seals with the male seal surface and the female seal surface, a seal structure according to claim 1, wherein a first gap (A1) is formed between the male seal surface and the female seal surface, where the male seal surface and the female seal surface are arranged parallel to each other with a predetermined gap therebetween, and a second gap (A2) is formed on a side closer to the male fitting portion and the female fitting portion than the first gap, where the gap is wider than the predetermined gap, the inner seal portion is arranged across the first gap and the second gap, and in a circumferential cross section of the inner seal portion, at least one of a maximum thickness portion (32c) of the inner seal portion in a free state and a center of gravity (32d) of the inner seal portion, whichever is located radially inner, is located in the second gap.(Item 3) The seal structure according to item 1 or 2, wherein at least one of the male seal surface and the female seal surface that constitute the second gap has a tapered surface (25b) that is inclined relative to the male seal surface and the female seal surface that constitute the first gap, and wherein the second gap has a distance between the male seal surface and the female seal surface that gradually increases toward the male fitting portion and the female fitting portion. (Item 4) The seal structure according to item 3, wherein the tapered surface is formed on the female seal surface that constitutes the second gap. (Item 5) The seal structure according to item 4, wherein the seal structure has an O-ring (4) that seals between the outer periphery of the male fitting portion and the inner periphery of the female fitting portion, and wherein when the male fitting portion is inserted into the female fitting portion, the O-ring attached to the outer periphery of the male fitting portion abuts against the tapered surface. (Item 6) The seal structure according to any one of items 1 to 5, further comprising an annular outer seal portion (33) provided radially outward of the inner seal portion and on both sides of the plate surface of the retainer, the outer seal portion being disposed in the first gap and, when the first member and the second member are fastened, being in close contact with the male seal surface and the female seal surface to seal between the male seal surface and the female seal surface, and a maximum thickness portion (33a) of the outer seal portion in a free state being thinner than a maximum thickness portion of the inner seal portion in a free state. (Item 7) The seal structure according to item 6, wherein a circumferential cross section of the outer seal portion on one surface side of the retainer has a triangular shape whose base is in contact with the plate surface of the retainer. (Item 8) The seal structure according to item 7, wherein a circumferential cross section of the outer seal portion on one surface side of the retainer has a concave shape, with at least one of two sides excluding the base side curving inward. (Item 9) The seal structure according to any one of Items 1 to 8, further comprising a fastening member (5) that fastens the first member and the second member by bringing them close to each other, the first member and the second member being movable in the direction of a central axis of the fastening member, and the central axis of the fastening member being disposed away from the central axis of the seal washer.(Item 10) The seal structure according to any one of items 1 to 9, wherein the Shore A hardness of the inner seal portion is equal to or greater than 60 degrees and less than 90 degrees. (Item 11) The seal structure according to any one of items 1 to 9, wherein the Shore A hardness of the inner seal portion is equal to or greater than 65 degrees and less than 75 degrees. (Item 12) The seal structure according to any one of items 1 to 11, wherein a filling rate of the inner seal portion in the first gap portion and the second gap portion is equal to or greater than 70% and less than 100%.

[0180] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure.

Claims

1. A first member (1) having a male seal surface (15) and a male mating portion (14) formed on the male seal surface so as to protrude from the male seal surface; a second member (2) having a female seal surface (25) opposing the male seal surface and a female mating portion (24) formed on the female seal surface so that the male mating portion can be inserted; an annular retainer (31) and a seal washer (3) having an annular inner seal portion (32) provided on the inner periphery of the retainer, and sandwiched between the male seal surface and the female seal surface while positioned on the outer periphery of the male mating portion; the first member and the second member are fastened together so as to come close to each other and compress the inner seal portion at the male seal surface and the female seal surface; the inner seal portion seals by tightly contacting each of the male seal surface and the female seal surface; Between the male side seal surface and the female side seal surface, a first gap portion (A1) is formed in which the male side seal surface and the female side seal surface are arranged parallel to each other with a predetermined distance between them, and a second gap portion (A2) is formed in which a distance wider than the predetermined distance is provided on the side closer to the male side fitting portion and the female side fitting portion than the first gap portion, the inner seal portion is arranged across the first gap portion and the second gap portion, and in a circumferential cross section of the inner seal portion, at least the one located radially inward of the maximum thickness portion (32c) of the inner seal portion in a free state and the center of gravity (32d) of the inner seal portion is located in the second gap portion.

2. A seal structure as described in claim 1, wherein a compressive force acts on the inner seal portion in the second gap portion from at least one of the male seal surface and the female seal surface in a direction different from the thickness direction of the seal washer.

3. A seal structure as described in claim 1, wherein at least one of the male seal surface and the female seal surface that constitute the second gap portion has a tapered surface (25b) that is inclined relative to the male seal surface and the female seal surface that constitute the first gap portion, and the second gap portion has a gradually increasing distance between the male seal surface and the female seal surface toward the male fitting portion and the female fitting portion.

4. The seal structure according to claim 3, wherein the tapered surface is formed on the female seal surface that constitutes the second gap portion.

5. A seal structure as described in claim 4, which is provided with an O-ring (4) that seals between the outer periphery of the male fitting portion and the inner periphery of the female fitting portion, and wherein the O-ring abuts against the tapered surface when the male fitting portion is inserted into the female fitting portion.

6. A seal structure as described in claim 1, which is provided with an annular outer seal portion (33) provided radially outward of the inner seal portion and on both sides of the plate surface of the retainer, wherein the outer seal portion is positioned in the first gap portion and, when the first member and the second member are fastened, is in close contact with the male seal surface and the female seal surface to seal between the male seal surface and the female seal surface, and the maximum thickness portion (33a) of the outer seal portion in a free state is thinner than the maximum thickness portion of the inner seal portion in a free state.

7. A seal structure as described in claim 6, wherein the circumferential cross section of the outer seal portion on one side of the retainer is triangular in shape, with its base in contact with the plate surface of the retainer and having an acute angle that protrudes from the plate surface of the retainer.

8. A seal structure according to claim 7, wherein at least one of the two sides of the outer seal portion on one side of the retainer in a circumferential cross section, excluding the bottom side, is concave and curved inward.

9. A seal structure as described in claim 1, further comprising a fastening member (5) that fastens the first member and the second member by bringing them close to each other, the first member and the second member being movable in the direction of the central axis of the fastening member, and the central axis of the fastening member being positioned away from the central axis of the seal washer.

10. The seal structure according to claim 1, wherein the Shore A hardness of the inner seal portion is equal to or greater than 60 degrees and less than 90 degrees.

11. The seal structure according to claim 1, wherein the Shore A hardness of the inner seal portion is equal to or greater than 65 degrees and less than 75 degrees.

12. The seal structure according to claim 1, wherein the filling rate of the inner seal portion in the first gap and the second gap is 70% or more and less than 100%.

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