Gasket for fuel cell

Abstract

To provide a gasket for fuel cells, capable of retaining adhesiveness between a gasket and a separator base material while ensuring sealability by the gasket.SOLUTION: A gasket 50 includes a sheet material 51A bonded to a surface of a separator base material 12, and a seal material 52 bonded to the surface of the separator base material 12 so as to cover the sheet material 51A, the seal material having higher compressive elastic deformability than the sheet material 51A. In a cross section of the gasket 50 in a width direction, the seal material 52 is bonded to the separator base material 12 on the outside of both ends of the sheet material 51A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gasket for a fuel cell that is bonded to a separator substrate for the fuel cell. [Background technology]

[0002] Conventionally, a single cell of a fuel cell is manufactured by sandwiching a membrane electrode assembly having gas diffusion layers formed on both sides between a pair of separators. The single cells are stacked in the thickness direction to form a fuel cell stack. For example, Patent Document 1 proposes a gasket that is placed on a separator substrate for a fuel cell to improve the sealing performance between the single cells. Each separator includes a separator substrate and a gasket, and the gasket is bonded to the separator substrate via an adhesive. Specifically, the adhesive is applied to the separator substrate so that the width of the adhesive is larger than the width of the gasket in a cross section in the width direction of the gasket. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-005026 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, even if the gasket is bonded to the separator substrate with an adhesive as disclosed in Patent Document 1, when a compressive load is applied to the gasket, the gasket deforms in the width direction, causing a shear stress to act between the separator substrate and the gasket. Such a shear stress may cause the gasket to peel off from the separator substrate.

[0005] The present invention has been made in consideration of these points, and provides a gasket for a fuel cell that can maintain adhesion between the gasket and a separator substrate while ensuring the sealing properties of the gasket. [Means for solving the problem]

[0006] In view of the above problems, the gasket for a fuel cell of the present invention is a gasket for a fuel cell that is adhered to a separator substrate for a fuel cell, the gasket comprising a sheet material adhered to a surface of the separator substrate, and a sealing material that is adhered to the surface of the separator substrate so as to cover the sheet material and has a higher compressive elastic deformation property than the sheet material, and is characterized in that, in a cross section of the width direction of the gasket, the sealing material is adhered to the separator substrate outside both ends of the sheet material. Effect of the Invention

[0007] According to the present invention, when a compressive load acts on the gasket, the sealant undergoes compressive elastic deformation, and shear stress is generated between the sealant and the separator substrate. In the cross section of the gasket in the width direction, the sealant is bonded to the separator substrate outside both ends of the sheet material, so that both sides of the sealant deform as relief portions for the shear stress, and the sealant can be maintained in a state fixed to the separator substrate via the sheet material. In this way, the adhesiveness between the gasket and the separator substrate can be maintained while ensuring the sealing performance of the gasket. [Brief description of the drawings]

[0008] [Figure 1] 1. (a) is a schematic perspective view of a fuel cell (single cell), and (b) is a diagram for explaining a method for manufacturing a fuel cell stack including the single cell cut along the line AA in FIG. [Diagram 2] FIG. 1A is a cross-sectional view of a gasket for a fuel cell according to the present embodiment, and FIG. 1B is a cross-sectional view of a comparative gasket for a fuel cell. [Diagram 3]2(a) to 2(d) are diagrams showing modified examples of the gasket for the fuel cell shown in FIG. 2(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a gasket for a fuel cell according to this embodiment will be described with reference to Figs. 1 to 3. A fuel cell stack (fuel cell) 1 shown in Fig. 1(b) includes a laminate 1A in which unit cells 40 are laminated in the thickness direction. Here, as shown in Fig. 1(a), the unit cell 40 is a cell in which a power generation unit 11 is sandwiched between a pair of separators 12A and 12B. The power generation unit 11 is a member in which a membrane electrode gas diffusion layer assembly (not shown) in which gas diffusion layers (not shown) are laminated on both sides of a membrane electrode assembly (not shown) is fixed by a resin frame (not shown). Hydrogen gas is supplied to one side of the power generation unit 11, and oxidant gas is supplied to the other side, and electricity is generated in the membrane electrode assembly.

[0010] The single cell 40 has openings 14a and 14f through which hydrogen gas passes, and openings 14c and 14d through which oxidant gas passes. Furthermore, the single cell 40 has openings 14b and 14e through which cooling water passes between the stacked single cells 40. The cooling water supplied from the opening 14b passes through a grooved flow path 11a formed on the surface of the separator 12A (separator substrate 12) and is discharged from the opening 14c. Note that, among the surfaces of the separator 12A, a flow path through which the above-mentioned hydrogen gas or oxidant gas flows is formed on the surface facing the power generation unit 11. Note that, although the single cell of the fuel cell is water-cooled as an example in this embodiment, the single cell of the fuel cell may be air-cooled, and in this case, air may flow instead of cooling water.

[0011] One separator 12A is composed of a separator substrate 12 and a gasket 50. The other separator 12B is composed only of the separator substrate 12. The gasket 50 is a member that partitions the flow paths of hydrogen gas, oxidizer gas, and coolant between the stacked unit cells 40, 40 and seals these fluids so that these fluids can flow. Examples of materials for the separator substrate 12 include metal materials such as titanium alloys and stainless steel, and graphite materials obtained by mixing graphite powder and resin.

[0012] 1(b), when manufacturing the fuel cell stack 1, a stack 1A in which a plurality of unit cells 40, 40, ... are stacked is disposed between insulating plates 20, 20, and current collector plates 30 are disposed at the lower and upper ends. The stack 1A made up of the plurality of unit cells 40, 40, ... is compressed and pressurized in the stacking direction between the pair of current collector plates 30, 30, and a compressive load is applied to the gasket 50. As a result, the flow paths through which the hydrogen gas, oxidant gas, and coolant flow through the unit cells 40 flow are sealed by the gasket 50.

[0013] As shown in FIG. 2, the gasket 50 includes a sheet material 51A and a sealing material 52. The sheet material 51A is a sheet-like member obtained by hollowing out a single sheet according to the shape of the gasket 50, and is adhered to the surface of the separator substrate 12. The sealing material 52 is adhered to the surface of the separator substrate 12 so as to cover the sheet material 51A, and is a member having higher compressive elastic deformation than the sheet material 51A. The sheet material 51A and the sealing material 52 are integrally formed. In this embodiment, the sheet material 51A is embedded in the sealing material 52 so that the contact surface of the surface of the sheet material 51A that comes into contact with the separator substrate 12 is exposed.

[0014] Here, the fact that sealing material 52 has a higher compressive deformability than sheet material 51A means that the material of sealing material 52 has a smaller elastic modulus (Young's modulus) than the material of sheet material 51A. Therefore, when the above-mentioned compressive load is applied, sealing material 52 deforms more in the stacking direction than sheet material 51A.

[0015] Here, examples of the material for sheet material 51A include acrylic resin, silicone resin, urethane resin, olefin resin, epoxy resin, or a combination thereof. Sheet material 51A may also be a three-layered member in which the above-mentioned resin is used as a core material and adhesive resin is applied to both sides of the core material. Examples of the material for seal material 52 include rubber materials such as silicone rubber.

[0016] 2(a), in a cross section of the gasket 50 in the width direction, the sealant 52 is adhered to the separator substrate 12 on the outer side of both ends of the sheet material 51A. A contact width W1 of the gasket 50 (sealant 52) ​​with the separator substrate 12 is larger than a contact width W2 of the sheet material 51A.

[0017] 2(b), in the conventional gasket 90, when a compressive load acts on the gasket 90, the gasket 90 is deformed, and a large shear stress acts between the separator 12A and the gasket 90. There is a risk that the gasket 90 will peel off from the separator substrate 12 due to such a shear stress.

[0018] However, according to this embodiment, when the above-mentioned compressive load acts on the gasket 50, the sealant 52 undergoes compressive elastic deformation, and shear stress is generated between the sealant 52 and the separator substrate 12 (at the interface). In the cross section of the gasket 50 in the width direction, the sealant 52 is bonded to the separator substrate 12 on the outer side of both ends of the sheet material 51A. Therefore, both sides of the sealant 52 are easily deformed as a relief portion for the shear stress, and the shear stress acting on the center of the sealant 52 is dispersed and reduced. As a result, the sealant 52 can stably maintain a state in which it is fixed to the separator substrate 12 via the sheet material 51A. In this way, the adhesiveness between the gasket 50 and the separator substrate 12 can be maintained while ensuring the sealing property of the gasket 50.

[0019] 3(a), the sheet material 51B may be divided into a plurality of (for example, two) separate sheet materials 51b, 51b. The separate sheet materials 51b, 51b are bonded to the separator substrate 12 with a gap therebetween. With this configuration, the stress acting on the outer side of the sealing material 52, which is susceptible to shear stress, can be dispersed to the center.

[0020] 3(b), at least one (for example, two) convex portions 51c, 51c may be formed on the surface of the sheet material 51C in contact with the sealing material 52. This forms apparent concaves and convexes on the surface of the sheet material 51C, so that when the sealing material 52 is compressed, the steps of the sealing material 52 can distribute the compressive stress of the sealing material 52, thereby dispersing the shear stress.

[0021] 3(c), corners 51d on both sides of sheet material 51D in contact with sealing material 52 may be rounded (corners 51d may be rounded). By rounding corners 51d of sheet material 51D, the compressive stress of sealing material 52 can be released to the outside, and the absolute value of the shear stress can be reduced.

[0022] 3(d), the sheet material 51E may be composed of a lower layer 51e bonded to the separator substrate 12, and at least one (for example, two spaced apart) upper layer 51f, 51f laminated on the lower layer 51e so that a stepped protrusion is formed on the lower layer 51e. This allows the steps of the sealing material 52 to distribute the compressive stress of the sealing material 52 and disperse the shear stress when the sealing material 52 is compressed. [Explanation of symbols]

[0023] 1: fuel cell stack (fuel cell), 12: separator substrate, 50: gasket, 51A to 51B: sheet material, 52: sealing material, 40: single cell

Claims

[Claim 1] A gasket for a fuel cell that is bonded to a separator substrate for the fuel cell, comprising: The gasket is A sheet material adhered to a surface of the separator substrate; a sealing material that is attached to a surface of the separator substrate so as to cover the sheet material and has a higher compressive elastic deformation property than the sheet material; A gasket for a fuel cell, wherein in a cross section of the gasket in the width direction, the sealing material is adhered to the separator substrate outside both ends of the sheet material.

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