fuel cell

Abstract

This technology provides a way to suppress damage to power generation equipment. [Solution] The fuel cell cell comprises a pair of separators, each having a first separator having a first main body and a first bead seal portion protruding from the first main body toward the power generator, and a second separator having a second main body and a second bead seal portion protruding from the second main body toward the power generator. The first bead seal portion has a pair of first inclined portions, a first surface portion located between the pair of first inclined portions and in contact with the power generator, and a first connecting portion connecting the pair of first inclined portions and the first surface portion and in contact with the power generator. The second bead seal portion has a pair of second inclined portions, a second surface portion located between the pair of second inclined portions, facing the first surface portion and in contact with the power generator, which is shorter than the first surface portion, and a second connecting portion connecting the pair of second inclined portions and the second surface portion and in contact with the power generator, which does not overlap with the first connecting portion in the stacking direction.

Description

[Technical Field]

[0001] The present disclosure relates to a fuel cell. [Background Art]

[0002] There is known a fuel cell in which a power generation body is sandwiched between a pair of separators formed with beads protruding toward the power generation body having an electrolyte membrane. Patent Document 1 describes a bead having a width of less than 0.5 mm. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2017-63018 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] When the width of the bead is narrow, when the power generation body and the separators are stacked and a fastening load is applied in the stacking direction, stress is concentrated on the bead, which may damage the power generation body. [Means for Solving the Problem]

[0005] The present disclosure has been made to solve the above problem, and can be implemented as the following embodiments.

[0006] According to an embodiment of the present disclosure, a fuel cell is provided. The fuel cell is a pair of separators arranged on both sides of a power generator, comprising: a first separator having a first body portion and a first bead seal portion projecting from the first body portion toward the power generator; and a second separator having a second body portion and a second bead seal portion projecting from the second body portion toward the power generator. The first bead seal portion has a pair of first inclined portions, a first surface portion located between the pair of first inclined portions and in contact with the power generator, and a first connecting portion connecting the pair of first inclined portions and the first surface portion and in contact with the power generator. The second bead seal portion includes a pair of second inclined portions, a second surface portion located between the pair of second inclined portions, facing the first surface portion and in contact with the power generation body, the second surface portion being shorter than the first surface portion, and a second connecting portion connecting the pair of second inclined portions and the second surface portion and in contact with the power generation body, the second connecting portion not overlapping with the first connecting portion in the stacking direction in which the power generation body and the pair of separators are stacked. In this type of fuel cell, the second surface is shorter than the first surface, and the first and second connection points do not overlap in the stacking direction. Therefore, when a load is applied in the stacking direction, stress concentration and damage to the power generation unit can be suppressed.

[0007] Furthermore, this disclosure can be implemented in various forms, for example, as a separator for fuel cell cells, a fuel cell stack comprising multiple stacked fuel cell cells, or a method for manufacturing fuel cell cells. [Brief explanation of the drawing]

[0008] [Figure 1] This is an explanatory diagram showing a disassembled fuel cell. [Figure 2] This is a cross-sectional view showing the schematic structure of a fuel cell cell. [Figure 3] This is an enlarged view of the P1 portion in Figure 2. [Modes for carrying out the invention]

[0009] Figure 1 is an explanatory diagram showing an exploded view of a fuel cell cell 100 in one embodiment of the present disclosure. Figure 2 is a cross-sectional view taken along the line II-II in Figure 1 of a stack of fuel cell cells 100 arranged in a stack. Figure 3 is an enlarged view of portion P1 in Figure 2.

[0010] The fuel cell cell 100 is a polymer electrolyte fuel cell that generates electricity by receiving hydrogen as the cathode gas and oxygen as the anode gas as reaction gases. The fuel cell cell 100 comprises a power generator 10, a first separator 20, and a second separator 30.

[0011] The power generation unit 10 is a component formed by joining the power generation unit 11 and the frame member 12. The power generation unit 11 is positioned and joined to the central hole 13 of the frame member 12.

[0012] The power generation unit 11 comprises an electrolyte membrane (not shown), catalyst layers (not shown) formed adjacent to both sides of the electrolyte membrane, and a gas diffusion layer (not shown) formed adjacent to one side of the catalyst layer. The electrolyte membrane is a solid polymer thin film that exhibits good proton conductivity in a wet state. The electrolyte membrane is composed of, for example, an ion exchange membrane made of a fluororesin. The catalyst layer comprises a catalyst that promotes the chemical reaction between hydrogen and oxygen, and carbon particles supporting the catalyst. The electrolyte membrane and catalyst layer together are also called a membrane electrode assembly (MEA).

[0013] The gas diffusion layer is provided adjacent to one of the catalyst layers. The gas diffusion layer diffuses the reaction gas used in the electrode reaction along the plane of the electrolyte membrane and is composed of a porous diffusion layer substrate. As the diffusion layer substrate, porous substrates with conductivity and gas diffusion properties such as carbon fiber substrates, graphite fiber substrates, and foamed metals are used. This electrolyte membrane, catalyst layer, and gas diffusion layer together are also called a membrane electrode gas diffusion layer assembly (MEGA).

[0014] In this embodiment, the frame member 12 is an insulating sheet made of resin. A sealing member 14 is provided in a substantially rectangular shape on the periphery of the surface of the frame member 12. The sealing member 14 is provided in a position opposite to the first bead seal portion 22 and the second bead seal portion 32, which will be described later.

[0015] A pair of first separators 20 and second separators 30 are arranged along both sides of the power generator 10. The first separators 20 and second separators 30 are formed, for example, by press-forming metal sheets made of stainless steel, titanium, or an alloy thereof.

[0016] The first separator 20 has a first main body portion 21 and a first bead seal portion 22 that protrudes from the first main body portion 21 toward the power generator 10. In this embodiment, the first bead seal portion 22 is formed in a substantially rectangular shape on the peripheral edge of the surface of the first separator 20. The peripheral edge of the first bead seal portion 22 is the region near the inner side of the outer peripheral edge of the first bead seal portion 22. Figure 2 is a cross-sectional view in a direction intersecting the direction in which the first bead seal portion 22 extends. The first bead seal portion 22 has a first surface portion 23, a pair of first inclined portions 24, and a first connecting portion 25.

[0017] In this embodiment, the first surface portion 23 is a plane in contact with the power generation body 10. The first surface portion 23 is located between a pair of first inclined portions 24.

[0018] As shown in Figure 2, the pair of first inclined portions 24 are configured such that, when viewed along a direction intersecting the direction in which the first bead seal portion 22 extends, one plane is inclined from the first main body portion 21 toward one end of the first surface portion 23, and the other plane is inclined from the first main body portion 21 toward the other end of the first surface portion 23. The pair of first inclined portions 24 are inclined in a direction that brings them closer to each other from the first main body portion 21 toward the first surface portion 23. More specifically, the inclination directions of the pair of first inclined portions 24 are configured to intersect on the power generation body 10 side in the protruding direction of the first bead seal portion 22 when each is virtually extended.

[0019] The first connecting portion 25 is a portion that connects the first surface portion 23 and the pair of first inclined portions 24. The first connecting portion 25 has a portion continuous from one end of the first surface portion 23 and a portion continuous from the other end of the first surface portion 23. That is, the first connecting portion 25 is a portion corresponding to a corner portion of the first bead seal portion 22. The first connecting portion 25 is in contact with the power generating body 10. Therefore, the first connecting portion 25 is a portion capable of applying stress to the power generating body 10 in the stacking direction in which the power generating body 10 and the pair of separators 20, 30 are stacked.

[0020] The second separator 30 includes a second main body portion 31 and a second bead seal portion 32 protruding from the second main body portion 31 toward the power generating body 10. In the present embodiment, the second bead seal portion 32 is formed in a substantially rectangular shape at a peripheral edge portion on the surface of the second separator 30. The peripheral edge portion of the second bead seal portion 32 is a region near the inner side of the outer peripheral edge of the second bead seal portion 32. The second bead seal portion 32 includes a second surface portion 33, a pair of second inclined portions 34, and a second connecting portion 35.

[0021] In the present embodiment, the second surface portion 33 is a flat surface in contact with the power generating body 10. The second surface portion 33 is located between the pair of second inclined portions 34. As shown in FIG. 2, when viewed along a direction intersecting the extending direction of the second bead seal portion 32, a length L2 of the second surface portion 33 in the direction in which the second surface portion 33 and the pair of second inclined portions 34 connect (hereinafter also referred to as "width direction") is shorter than a length L1 of the first surface portion 23 in the width direction. In the present embodiment, the length L2 is 5 mm or more. Further, it is preferable that the first bead seal portion 22 and the second bead seal portion 32 are configured such that the length L1 and the length L2 satisfy the following formula (1).

[0022] (L1-L2) 2 >4A×(2R-A)...(1) Here, A is the thickness of the seal member 14, and R is the radius of curvature of the second connecting portion 35.

[0023] The pair of second inclined portions 34 are configured such that, when viewed along a direction intersecting the direction in which the second bead seal portion 32 extends, one plane is inclined from the second main body portion 31 toward one end of the second surface portion 33, and the other plane is inclined from the second main body portion 31 toward the other end of the second surface portion 33. The pair of second inclined portions 34 are inclined in a direction that brings them closer to each other from the second main body portion 31 toward the second surface portion 33. More specifically, the inclination directions of the pair of second inclined portions 34 are configured to intersect on the power generation body 10 side in the protruding direction of the second bead seal portion 32 when each is virtually extended.

[0024] In the stacking direction in which the power generator 10 and the pair of separators 20 and 30 are stacked, the ends of the pair of first inclined portions 24 on the first main body portion 21 side and the ends of the pair of second inclined portions 34 on the second main body portion 31 side coincide. That is, the length of the first bead seal portion 22 in the width direction and the length of the second bead seal portion 32 in the width direction are the same.

[0025] The second connecting portion 35 is the part that connects the second surface portion 33 and the pair of second inclined portions 34. The second connecting portion 35 has a portion that is continuous from one end of the second surface portion 33 and a portion that is continuous from the other end of the second surface portion 33. That is, the second connecting portion 35 is the part that corresponds to the corner of the second bead seal portion 32. The second connecting portion 35 is in contact with the power generation body 10. Therefore, the second connecting portion 35 is a part that can apply stress to the power generation body 10 in the stacking direction in which the power generation body 10 and the pair of separators 20 and 30 are stacked. The second connecting portion 35 does not overlap with the first connecting portion 25 in the stacking direction.

[0026] If the first connection portion 25 and the second connection portion 35 overlap in the stacking direction, stress will concentrate in the overlapping region when a load is applied in the stacking direction. In this embodiment, the second surface portion 33 is shorter than the first surface portion 23, and the first connection portion 25 and the second connection portion 35 do not overlap in the stacking direction. Therefore, it is possible to suppress the concentration of stress in a specific region when a load is applied in the stacking direction. Consequently, damage to the power generator 10 can be suppressed.

[0027] Furthermore, the widthwise length L1 of the first surface and the widthwise length L2 of the second surface are both 5 mm or more. Therefore, leakage can be suppressed when foreign matter gets between the bead seals 22 and 32 and the power generator 10.

[0028] B. Other embodiments: (B1) In the embodiment described above, the first surface portion 23 and the first inclined portion 24, the second surface portion 33, and the second inclined portion 34 are all planar. However, the first surface portion 23 and the first inclined portion 24, the second surface portion 33, and the second inclined portion 34 may be curved surfaces. Furthermore, the first inclined portion 24 and the second inclined portion 34 may be composed of multiple planar and / or curved surfaces.

[0029] (B3) In the embodiment described above, the frame member 12 is an insulating sheet on which the sealing member 14 is provided. However, the frame member 12 may be a member made of pressure-sensitive adhesive, in which the sealing member 14 is omitted. In this case, A in formula (1) described above is the length along the thickness direction of the frame member 12 from the position on the surface of the frame member 12 on the second separator 30 side where the second separator 30 is not in contact to the position where the second bead seal portion 32 is in contact.

[0030] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve the problems described above or to achieve some or all of the effects described above. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0031] 10...Power generator, 11...Power generation unit, 12...Frame member, 13...Hole, 14...Sealing member, 20...First separator, 21...First main body, 22...First bead seal, 23...First surface, 24...First inclined section, 25...First connection section, 30...Second separator, 31...Second main body, 32...Second bead seal, 33...Second surface, 34...Second inclined section, 35...Second connection section, 100...Fuel cell cell

Claims

[Claim 1] It is a fuel cell cell, A pair of separators arranged on both sides of a power generator, comprising: a first separator having a first main body and a first bead seal portion protruding from the first main body toward the power generator; and a second separator having a second main body and a second bead seal portion protruding from the second main body toward the power generator; The first bead seal portion is, A pair of first inclined sections, A first surface portion located between the pair of first inclined portions and in contact with the power generation body, It has a first connecting portion that connects the pair of first inclined portions and the first surface portion and is in contact with the power generation body, The second bead seal portion is, A pair of second inclined sections, A second surface located between the pair of second inclined portions, facing the first surface and in contact with the power generation body, the second surface being shorter than the first surface, A fuel cell having a second connecting portion that connects the pair of second inclined portions and the second surface portion and is in contact with the power generation body, the second connecting portion not overlapping with the first connecting portion in the stacking direction in which the power generation body and the pair of separators are stacked.

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