Gaskets, fuel cells, and water electrolysis devices

Abstract

Provided are a gasket, a fuel cell, and a water electrolysis device that can enhance the effect of suppressing leakage of a fluid to be sealed even in an environment where the pressure of the fluid to be sealed is high. [Solution] A gasket (300) includes a reinforcing member (310) and a gasket body (320) made of a rubber-like elastic material and integrally formed with the reinforcing member (310). The gasket body (320) is integrally formed with a thin portion (321) provided so as to cover part of one surface of the reinforcing member (310) along an inner peripheral edge (311b) of the opening, and a thick portion (322) provided so as to protrude toward both sides within the opening. The Young's modulus of the reinforcing member (310) is higher than that of the gasket body (320). When the thickness of the reinforcing member (310) is TF, the thickness of the thin portion (321) is TB, and the maximum thickness of the thick portion (322) is TG, the Young's modulus of the gasket body (320) is 1

Description

[Technical Field]

[0001] The present invention relates to a gasket, a fuel cell, and a water electrolysis device. [Background technology]

[0002] Fuel cells and water electrolysis systems are generally constructed using a cell stack including multiple unit cells, each of which has a membrane unit including an electrolyte membrane and a pair of separators arranged on either side of the membrane unit. These systems are also provided with passages through which various fluids flow, and gaskets are provided to prevent fluid leakage from the passages.

[0003] There are various types of gaskets, such as a rubber-like elastic body integrally molded as a gasket on a membrane unit or a separator, but there are also many cases where a gasket is required to be used as a separate component from the membrane unit or separator. A conventional gasket will be described with reference to Fig. 6. Fig. 6 is a schematic cross-sectional view showing a conventional gasket in use. Fig. 6(a) shows a state where no fluid is flowing through the passage, and Fig. 6(b) shows a state where the pressure of the fluid flowing through the passage is high.

[0004] In the illustrated example, a gasket 500 made of a rubber-like elastic material is disposed between a pair of separators 200. This can prevent fluid leakage from the passages. However, as the pressure P of the fluid flowing through the passages increases, the gasket 500 deforms and expands toward the side opposite the fluid to be sealed. This causes the gasket 500 to deform and become thinner, which reduces the surface pressure on the separators 200. Therefore, depending on the fluid pressure, the fluid may blow through as indicated by the arrow L in the figure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-117140 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a gasket, a fuel cell, and a water electrolysis device that can enhance the effect of suppressing leakage of a fluid to be sealed even in an environment where the pressure of the fluid to be sealed is high. [Means for solving the problem]

[0007] The present invention employs the following means to solve the above problems.

[0008] That is, the gasket of the present invention is a thin plate-like reinforcing member having an opening that serves as a passage for the fluid to be sealed; a gasket body made of a rubber-like elastic material that is integrally provided on the reinforcing member so as to cover the entire inner circumferential surface of the opening; A gasket comprising: The gasket body is a thin-walled portion provided to cover a portion of one surface of the reinforcing member along an inner periphery of the opening; a thick portion provided within the opening so as to protrude toward both surfaces; In addition to being equipped with the Young's modulus of the reinforcing member is higher than the Young's modulus of the gasket body; When the thickness of the reinforcing member is TF, the thickness of the thin portion is TB, and the maximum thickness of the thick portion is TG, 3 <TG / (TF+TB)≦60 The present invention is characterized in that:

[0009] According to the present invention, even if the pressure of the fluid to be sealed against the thick-walled portion of the gasket body increases, the reinforcing member can prevent the gasket body from expanding. This can prevent the thick-walled portion from becoming thinner, thereby preventing a decrease in sealing performance. Furthermore, by setting the relationship between Young's modulus and the relationship between TF, TB, and TG to satisfy the above-mentioned relationships, it is possible to effectively prevent deformation of the gasket body due to an increase in the pressure of the fluid to be sealed.

[0010] The fuel cell of the present invention comprises: A fuel cell including a plurality of unit cells, each unit cell having a membrane unit including an electrolyte membrane and a pair of separators disposed on both sides of the membrane unit, The membrane unit is characterized by including the above-mentioned gasket disposed in at least one of the gaps between the separators and the gaps between the separators and the membrane units.

[0011] The water electrolysis device of the present invention comprises: A water electrolysis apparatus including a plurality of unit cells, each unit cell including a membrane unit including an electrolyte membrane and a pair of separators disposed on both sides of the membrane unit, The membrane unit is characterized by including the above-mentioned gasket disposed in at least one of the gaps between the separators and the gaps between the separators and the membrane units. [Effects of the Invention]

[0012] As described above, according to the present invention, even in an environment where the pressure of the fluid to be sealed is high, the effect of suppressing leakage of the fluid to be sealed can be improved. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the main configuration of a fuel cell according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the main configuration of a water electrolysis apparatus according to an embodiment of the present invention. [Figure 3]FIG. 3 is a plan view of a separator according to an embodiment of the present invention. [Figure 4] FIG. 4 is a plan view of a gasket according to an embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view of a gasket according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a state in which a conventional gasket is used. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following detailed description of the present invention will be given by way of example with reference to the accompanying drawings, although the dimensions, materials, shapes, relative positions, etc. of the components described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0015] (Example) A gasket, a fuel cell, and a water electrolysis device according to an embodiment of the present invention will be described with reference to Figs. 1 to 5. Fig. 1 is a schematic cross-sectional view showing the main components of a fuel cell according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing the main components of a water electrolysis device according to an embodiment of the present invention. Fig. 3 is a plan view of a separator according to an embodiment of the present invention. The cross-sectional view of the lower separator in Fig. 1 corresponds to the AA cross-section in Fig. 3. Fig. 4 is a plan view of a gasket according to an embodiment of the present invention. 5A and 5B are schematic cross-sectional views of a gasket according to an embodiment of the present invention, and Fig. 5A corresponds to the cross-sectional view taken along line BB in Fig. 4. Fig. 5A shows the gasket alone, while Fig. 5B and Fig. 5C show portions of the cross-sectional view of a single fuel cell in which the gasket has been incorporated.

[0016] <Fuel cell> A fuel cell to which the gasket according to this embodiment can be applied will be described with reference to FIG. 1. Generally, a fuel cell is configured as a cell stack consisting of a plurality of unit cells. FIG. 1 shows a schematic cross-sectional view of a portion of a unit cell. The unit cell is configured with an MEA 100A (Membrane Electrode Assembly) as a membrane unit and a pair of separators 200A provided on both sides thereof. Note that in the cell stack, there are also locations where separators are provided adjacent to each other without an MEA in between, in locations where a coolant flows. The MEA 100A includes an electrolyte membrane 110 and a pair of gas diffusion layers 120, 130 provided on both sides of the electrolyte membrane 110. The separator 200A has a recess 210 on the surface thereof, which serves as a fluid passage.

[0017] With the above configuration, fuel gas is supplied to one side of the MEA 100A and oxidant gas is supplied to the other side, causing a chemical reaction in the electrolyte membrane 110 to produce water and electrons, thereby generating electricity. Gaskets are provided in the fuel cell to prevent leakage of the fluids to be sealed (fuel gas, oxidant gas, water, and coolant).

[0018] <Water electrolysis device> A water electrolysis apparatus to which the gasket according to this embodiment can be applied will be described with reference to FIG. 2. Generally, a water electrolysis apparatus is configured as a cell stack consisting of a plurality of unit cells. FIG. 2 shows a schematic cross-sectional view of a portion of a unit cell. The unit cell is configured by a membrane unit 100B and a pair of separators 200B provided on both sides of the membrane unit 100B. The membrane unit 100B includes an electrolyte membrane 110 and current collectors 140 and 150 provided on both sides of the electrolyte membrane 110. The separator 200A has a recess 210 on the surface thereof, which serves as a fluid passage.

[0019] With the above configuration, when power is supplied while pure water is supplied to the cell, the pure water is decomposed into hydrogen ions and oxygen ions by the electrolyte membrane 110, and water containing oxygen molecules flows on one side of the membrane unit 100B, while water containing hydrogen molecules flows on the other side. In order to prevent leakage of the sealed fluids (pure water, water containing oxygen molecules, and water containing hydrogen molecules), the water electrolysis apparatus is provided with a gasket.

[0020] <Separator> The separator will be described in detail with particular reference to Figure 3. The separator 200A used in the fuel cell 10A and the separator 200B used in the water electrolysis system 10B have the same basic structure, so the specific structure will be described using the separator 200A as a representative.

[0021] The separator 200A has a recess 210 that serves as a fluid passage, and a plurality of manifolds (for convenience, referred to as a first manifold 221, a second manifold 222, and a third manifold 223) for supplying the fluid to each unit cell. For example, the first manifold 221 is used to allow fuel gas to flow, the second manifold 222 is used to allow oxidant gas to flow, and the third manifold 223 is used to allow cooling water to flow. This figure shows a configuration in which the fluid flowing through the first manifold 221 flows into the recess 210. In the figure, the thick dotted line ML indicates the area that faces the MEA 100A when a unit cell is configured. Also, in the figure, the thin dotted line SL indicates the area that faces the MEA 100A when a unit cell is configured. The seal line SL indicates the seal line where the gasket 300 (described later) fits tightly. As shown in the figure, the seal line SL surrounds the area where the pair of first manifolds 221 and recesses 210 are provided, and is configured to surround the second manifold 222 and the third manifold 223, respectively.

[0022] <Gasket> 4 and 5, a gasket 300 according to this embodiment will be described in detail. The gasket 300 according to this embodiment is composed of a thin plate-like reinforcing member 310 and a gasket body 320 made of a rubber-like elastic material (natural rubber, silicone rubber, EPDM, VMQ, etc.) that is integrally provided with the reinforcing member 310. The planar external dimensions of the gasket 300 according to this embodiment are set to be the same as the planar external dimensions of the separator 200A (similarly for the separator 200B). This simplifies assembly by simply arranging the gasket 300 so that it overlaps between adjacent separators 200A (separators 200B).

[0023] The reinforcing member 310 is made of a resin (PET, PE, PP, PPS, PEN, etc.) film, a rigid resin member, a metal (SUS, AL, etc.) member, or the like. The reinforcing member 310 is provided with a plurality of openings 311 that serve as passages for the fluid to be sealed. The plurality of openings 311 are provided so as to surround the outside of the area surrounded by the seal lines SL when the separator 200A (separator 200B) and the gasket 300 are overlapped. In other words, the seal lines SL are formed inside the inner circumferential surface 311a of the openings 311 and along the inner circumferential surface 311a of the openings 311.

[0024] Gasket body 320 is provided so as to cover the entire inner circumferential surface of each of a plurality of openings 311 provided in reinforcing member 310. Gasket body 320 is integrally provided with thin-walled portion 321 and thick-walled portion 322. Thin-walled portion 321 is provided so as to cover part of one surface of reinforcing member 310 along inner circumferential edge 311b of opening 311. Thick-walled portion 322 is provided so as to protrude toward both sides within the opening.

[0025] In this embodiment, the Young's modulus of the reinforcing member 310 is configured to be higher than that of the gasket body 320. When a resin film is adopted as the reinforcing member 310, the Young's modulus is 0.2 GPa to 0.5 GPa when the resin material is PE, 1.0 GPa to 2.0 GPa when the resin material is PP, and 2 GPa to 4 GPa when the resin material is PET. On the other hand, the Young's modulus of the gasket body 320 is 0.01 GPa to 0.1 GPa when the rubber material is natural rubber and 0.01 GPa to 0.1 GPa when the rubber material is silicone rubber.

[0026] Also, in this embodiment, the dimensions of each part are set so as to satisfy the following relationship. That is, when the thickness of the reinforcing member 310 is TF, the thickness of the thin portion 321 is TB, and the maximum thickness of the thick portion 322 is TG, it is set to satisfy 1 < TG / (TF + TB) ≤ 60. For example, the maximum value of TG can be set to 1.5 mm, and the minimum value of (TF + TB) can be set to 0.025 mm.

[0027] Furthermore, when the gasket 300 is incorporated into a single cell, the maximum thickness T2 of the gasket body 320 in the compressed state is configured to be larger than T1 (= TF + TB).

[0028] In the state where the gasket 300 configured as described above is incorporated into a single cell, the gasket 300 is disposed in at least one of the gaps between the separator and the electrolyte membrane and the gaps between the separators. Thereby, both surfaces of the thick portion 322 in the gasket body 320 contact the separator 200A and the electrolyte membrane 110 (see Fig. 5(b)) or contact each of the pair of separators 200A (see Fig. 5(c)). Thereby, leakage of the fluid flowing through the manifold and the fluid flowing through the concave portion 210 can be suppressed. Although Figs. 5(b) and 5(c) show the configuration in the case of a fuel cell, the same applies to a water electrolysis device.

[0029] <Advantages of the gasket, fuel cell, and water electrolysis device according to this embodiment> According to this embodiment, even when the pressure P (see FIGS. 5(b) and 5(c)) of the fluid to be sealed against the thick portion 322 in the gasket body 320 increases, the reinforcing member 310 can suppress the gasket body 320 from expanding. That is, since the reinforcing member 310 hardly deforms, the thick portion 322 is supported by the inner peripheral surface 311a of the reinforcing member 310, thereby suppressing the deformation of the gasket body 320 (thick portion 322). As a result, deformation that causes the thick portion 322 to become thinner can be suppressed, and a decrease in sealing performance can be suppressed. In this embodiment, by setting the relationship between the Young's modulus and the relationship between TF, TB, and TG to satisfy the above relationships, deformation of the gasket body 320 due to an increase in the pressure of the fluid to be sealed can be effectively suppressed. Note that if TG / (TF + TB) is set to 1 or less, there is a possibility that the thick portion 322 will not be compressed and leakage will occur. More preferably, it is desirable to satisfy 3 < TG / (TF + TB). Thereby, since the thick portion 322 can be sufficiently compressed while ensuring the rigidity of the reinforcing member 310, the sealing performance can be further improved. Also, if TG / (TF + TB) is made greater than 60, the effect of suppressing the deformation of the thick portion 322 becomes insufficient, and there is a possibility that the blow-through suppression effect will not be fully exerted. From the above, even in an environment where the pressure of the fluid to be sealed is high, the effect of suppressing leakage of the fluid to be sealed can be enhanced.

Explanation of reference numerals

[0030] 10A: Fuel cell 10B: Water electrolysis device 100A: MEA 100B: Membrane unit 110: Electrolyte membrane 120, 130: Gas diffusion layer 140, 150: Current collector 200, 200A, 200B: Separator 210: Recess 221: First manifold 222: Second manifold 223: Third manifold 300: Gasket 310: Reinforcement member 311: Opening 311a: Inner surface 311b: Inner edge 320: Gasket body 321: Thin section 322: Thick wall part

Claims

1. a thin plate-like reinforcing member having an opening that serves as a passage for the fluid to be sealed; a gasket body made of a rubber-like elastic material that is integrally provided on the reinforcing member so as to cover the entire inner circumferential surface of the opening; A gasket comprising: The gasket body is a thin-walled portion provided to cover a portion of one surface of the reinforcing member along an inner periphery of the opening; a thick portion provided within the opening so as to protrude toward both surfaces; In addition to being equipped with the Young's modulus of the reinforcing member is higher than the Young's modulus of the gasket body; When the thickness of the reinforcing member is TF, the thickness of the thin portion is TB, and the maximum thickness of the thick portion is TG, 3<TG / (TF+TB)≦60 A gasket characterized by satisfying the above.

2. A fuel cell including a plurality of unit cells, each unit cell having a membrane unit including an electrolyte membrane and a pair of separators disposed on both sides of the membrane unit, A fuel cell comprising the gasket according to claim 1, which is disposed in at least one of a gap between the separators and a gap between the separator and the membrane unit.

3. A water electrolysis apparatus including a plurality of unit cells, each unit cell including a membrane unit including an electrolyte membrane and a pair of separators disposed on both sides of the membrane unit, A water electrolysis apparatus comprising the gasket according to claim 1 , which is disposed in at least one of a gap between the separators and a gap between the separator and the membrane unit.

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