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 adhered to a separator base material for a fuel cell.

Background Art

[0002] Conventionally, a membrane electrode assembly having gas diffusion layers formed on both sides is sandwiched between a pair of separators to manufacture a single cell of a fuel cell. The single cells are stacked in the thickness direction to form a fuel cell stack. For example, Patent Document 1 proposes a gasket disposed on a separator base material for a fuel cell in order to enhance the sealing performance between the single cells. Each separator includes a separator base material and a gasket, and the gasket is adhered to the separator base material via an adhesive. Specifically, the adhesive is applied to the separator base material such that the width of the adhesive is larger than the width of the gasket in the cross section in the width direction of the gasket.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] <[ However, as shown in Patent Document 1, even when the gasket is adhered to the separator base material via an adhesive, when a compressive load acts on the gasket, shear stress acts between the separator base material and the gasket due to deformation in the width direction of the gasket. Such shear stress may cause the gasket to peel off from the separator base material.

[0005] The present invention has been made in view of these points, and aims to provide a gasket for a fuel cell that can maintain adhesion between the gasket and the separator substrate while ensuring sealing performance by the gasket. [Means for solving the problem]

[0006] In view of the above problems, the fuel cell gasket according to the present invention is a fuel cell gasket that is bonded to a separator substrate for a fuel cell, the gasket comprising a sheet material bonded to the surface of the separator substrate, and a sealing material that covers the sheet material and is bonded to the surface of the separator substrate, and has higher compressive elastic deformability than the sheet material, wherein in a cross-section in the width direction of the gasket, the sealing material is bonded to the separator substrate outside both ends of the sheet material. [Effects of the Invention]

[0007] According to the present invention, when a compressive load is applied to the gasket, the sealing material undergoes compressive elastic deformation, and shear stress is generated between the sealing material and the separator substrate. In the cross-section in the width direction of the gasket, the sealing material is bonded to the separator substrate outside of both ends of the sheet material. Therefore, both sides of the sealing material deform to act as shear stress relief portions, and the sealing material can maintain a fixed state to the separator substrate via the sheet material. In this way, the sealing performance of the gasket can be ensured while maintaining adhesion between the gasket and the separator substrate. [Brief explanation of the drawing]

[0008] [Figure 1] (a) is a schematic perspective view of a fuel cell (single cell), and (b) is a diagram illustrating a method for manufacturing a fuel cell stack including a single cell, cut along line AA in Figure 1. [Figure 2] (a) is a cross-sectional view of a fuel cell gasket according to this embodiment, and (b) is a cross-sectional view of a comparative fuel cell gasket. [Figure 3]Figures (a) to (d) show modified examples of the fuel cell gasket shown in Figure 2(a). [Modes for carrying out the invention]

[0009] The gasket for the fuel cell according to this embodiment will be described below with reference to Figures 1 to 3. The fuel cell stack (fuel cell) 1 shown in Figure 1(b) comprises a laminate 1A formed by stacking single cells 40 in the thickness direction. Here, as shown in Figure 1(a), the single 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 component in which a membrane electrode gas diffusion layer assembly (not shown), in which a gas diffusion layer (not shown) is stacked on both sides of a membrane electrode assembly (not shown), is fixed with a resin frame (not shown). Hydrogen gas is supplied to one side of the power generation unit 11, and an oxidizing gas is supplied to the other side, and power is generated in the membrane electrode assembly.

[0010] Each single cell 40 has openings 14a and 14f through which hydrogen gas passes, and openings 14c and 14d through which oxidizer gas passes. Furthermore, each single cell 40 has openings 14b and 14e through which cooling water flows between stacked single cells 40, 40. The cooling water supplied from opening 14b passes through the flow path 11a of the groove formed on the surface of the separator 12A (separator substrate 12) and is discharged from opening 14c. On the surface of the separator 12A facing the power generation unit 11, a flow path for the hydrogen gas or oxidizer gas described above is formed. In this embodiment, a single cell of a water-cooled fuel cell is exemplified, but the single cell of the fuel cell may also be air-cooled, in which case air may flow instead of cooling water.

[0011] One separator 12A consists of a separator base material 12 and a gasket 50. The other separator 12B consists only of the separator base material 12. The gasket 50 is a component that partitions the fluid passages between the stacked single cells 40, 40 so that hydrogen gas, oxidizing gas, and cooling water can flow through them, and also seals these fluids. The material of the separator base material 12 can be a metallic material such as titanium alloy or stainless steel, or a graphite material obtained by mixing graphite powder and resin.

[0012] As shown in Figure 1(b), when manufacturing the fuel cell stack 1, a laminate 1A made of multiple single cells 40, 40, ... is placed between insulating plates 20, 20, and current collector plates 30 are placed at the lower and upper ends, respectively. The laminate 1A, consisting of multiple single cells 40, 40, ... is compressed and pressurized in the stacking direction between a 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 hydrogen gas, oxidizer gas, and cooling water flow in the single cells 40 are sealed by the gasket 50.

[0013] As shown in Figure 2, the gasket 50 comprises a sheet material 51A and a sealing material 52. The sheet material 51A is a sheet-like member cut out from a single sheet according to the shape of the gasket 50, and is bonded to the surface of the separator base material 12. The sealing material 52 is bonded to the surface of the separator base material 12 so as to cover the sheet material 51A, and is a member with higher compressive elastic deformability than the sheet material 51A. The sheet material 51A and the sealing material 52 are integrally molded. In this embodiment, the sheet material 51A is embedded in the sealing material 52 such that the contact surface of the sheet material 51A that contacts the separator base material 12 is exposed.

[0014] Here, the statement that the sealant 52 has higher compressive deformability than the sheet material 51A means that the material of the sealant 52 has a lower modulus of elasticity (Young's modulus) than the material of the sheet material 51A. Therefore, when the aforementioned compressive load is applied, the sealant 52 deforms more significantly in the lamination direction than the sheet material 51A.

[0015] Here, the material for the sheet material 51A can be an acrylic resin, a silicone resin, a urethane resin, an olefin resin, an epoxy resin, or a combination thereof. The sheet material 51A may also be a three-layer structure in which the above-mentioned resin is used as a core material, and adhesive resins are applied to both sides of this core material. The material for the sealing material 52 can be a rubber material such as silicone rubber.

[0016] In this embodiment, as shown in Figure 2(a), in the cross-section of the gasket 50 in the width direction, the sealing material 52 is bonded to the separator base material 12 outside both ends of the sheet material 51A. The contact width W1 of the gasket 50 (sealing material 52) with respect to the separator base material 12 is greater than the contact width W2 of the sheet material 51A.

[0017] As shown in Figure 2(b), in conventional gaskets 90, when a compressive load is applied to the gasket 90, the deformation of the gasket 90 causes a large shear stress to act between the separator 12A and the gasket 90. Due to such shear stress, there was a risk that the gasket 90 would peel off from the separator base material 12.

[0018] However, according to this embodiment, when the above-mentioned compressive load is applied to the gasket 50, the sealing material 52 undergoes compressive elastic deformation, and shear stress is generated between the sealing material 52 and the separator base material 12 (interface). In the cross-section of the gasket 50 in the width direction, the sealing material 52 is bonded to the separator base material 12 outside both ends of the sheet material 51A. Therefore, both sides of the sealing material 52 are more easily deformed as shear stress relief areas, and the shear stress acting on the center of the sealing material 52 is distributed and reduced. As a result, the sealing material 52 can be stably maintained in a state fixed to the separator base material 12 via the sheet material 51A. In this way, the sealing performance of the gasket 50 can be ensured while maintaining adhesion between the gasket 50 and the separator base material 12.

[0019] As in the modified example shown in Fig. 3(a), the sheet material 51B may be composed of a plurality (for example, two) of divided sheet materials 51b, 51b that are divided. The divided sheet materials 51b, 51b are adhered to the separator base material 12 with a space therebetween. By configuring it in this way, the stress applied to the outside of the sealing material 52 where shear stress easily acts can be dispersed to the central part.

[0020] Also, as in the modified example shown in Fig. 3(b), at least one (for example, two) convex portions 51c, 51c may be formed on the surface of the sheet material 51C that contacts the sealing material 52. As a result, apparent irregularities are formed on the surface of the sheet material 51C. Therefore, when the sealing material 52 is compressed, the compression stress of the sealing material 52 can be dispersed by the step of the sealing material 52, and the shear stress can be dispersed.

[0021] Also, as in the modified example shown in Fig. 3(c), the corners 51d on both sides of the sheet material 51D that contacts the sealing material 52 may be rounded (the corners 51d may be R-processed). By rounding the corners 51d of the sheet material 51D, the compression stress of the sealing material 52 can be released to the outside, and the absolute value of the shear stress can be reduced.

[0022] Furthermore, as in the modified example shown in Fig. 3(d), the sheet material 51E may be composed of a lower layer 51e adhered to the separator base material 12 and at least one (for example, two spaced-apart) upper layers 51f, 51f laminated on the lower layer 51e such that stepped convex portions are formed on the lower layer 51e. As a result, when the sealing material 52 is compressed, the compression stress of the sealing material 52 can be dispersed by the step of the sealing material 52, and the shear stress can be dispersed.

Explanation of Reference Numerals

[0023] 1: Fuel cell stack (fuel cell), 12: Separator base material, 50: Gasket, 51A~51B: Sheet material, 52: Sealing material, 40: Single cell

Claims

[Claim 1] A fuel cell gasket that is bonded to a separator substrate for fuel cells, The aforementioned gasket is A sheet material adhered to the surface of the separator substrate, The sealing material is bonded to the surface of the separator substrate so as to cover the sheet material, and has higher compressive elastic deformability than the sheet material, A gasket for a fuel cell, characterized in that, in the cross-section of the gasket in the width direction, the sealing material is bonded to the separator substrate outside the ends of the sheet material.

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