JP2005268075A - Sealing structure of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve sealing properties with a simple structure and enable to assure proper sealing function, without being affected by vibrations or the like, especially, at loading to a vehicle. <P>SOLUTION: The sealing structure 51 is equipped with a first sealing member 42 integrated with a first metal separator 18, and a second sealing member 50 integrated with a second metal separator 20. The first sealing member 42 is provided with a first outerside convex seal 44a, protruding towards the second seal member 50; whereas, the second sealing member 50 is provided with a concave part 52a for storing only a tip of the first outerside convex seal 44a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a seal structure for a fuel cell including a power generation cell in which an electrolyte membrane / electrode structure in which an electrolyte membrane is disposed between a pair of electrodes is sandwiched by a pair of separators.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are provided on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched between separators. It has a power generation cell. This type of fuel cell is normally used as a stack by stacking a predetermined number of power generation cells.

  In this power generation cell, a fuel gas, for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas) is supplied to the anode side electrode, while an oxidant gas, for example, A gas or air mainly containing oxygen (hereinafter also referred to as oxygen-containing gas) is supplied. In the fuel gas supplied to the anode side electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode side electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  In the power generation cell described above, various seal structures are employed in order to keep the fuel gas and the oxidant gas airtight. For example, Patent Document 1 discloses a fuel cell gasket that can improve the sealing performance between an electrolyte membrane / electrode structure and a separator.

  As shown in FIG. 8, this fuel cell gasket has a gasket body 1 made of a metal or a resin sheet formed in a predetermined plane shape, and an empty space provided in the plane of the gasket body 1. A packing-like seal portion 3 made of a rubber-like elastic material is bonded to the peripheral portion of the hole portion 2 with an adhesive.

  The seal portion 3 is attached to the upper surface of the gasket body 1 and covers the upper surface, the one-surface seal portion 4 is attached to the lower surface of the gasket body 1 and covers the lower surface, An inner surface seal portion 7 that covers the inner surface 6 of the hole 3 is integrally provided. The one-surface seal portion 4 has a convex cross section, while the cross-section seal portion 5 has a trapezoidal cross section.

JP 2001-57220 A (FIG. 3)

  By the way, in the above-mentioned Patent Document 1, for example, when the top portion of the one-surface seal portion 4 is in contact with the seal surface 8, the air hole portion 2 is sealed in an airtight or liquid-tight manner. In that case, the top part of the one-surface seal | sticker part 4 and the seal surface 8 are substantially point-contacting, there exists a problem that a contact area is small and sufficient sealing function cannot be ensured.

  In addition, when the fuel cell is mounted on a fuel cell vehicle and used, deviation (lateral deviation) is likely to occur between the one-surface seal portion 4 and the seal surface 8 due to vibration or impact during travel. Thereby, there is a problem that the sealing function is lowered and the strength is lowered.

  The present invention solves this type of problem, and with a simple configuration, aims to improve sealing performance, and is particularly unaffected by on-vehicle vibration, etc., and ensures a good sealing function. It is an object of the present invention to provide a fuel cell seal structure capable of achieving the above.

  The present invention is a fuel cell seal structure including a power generation cell in which an electrolyte membrane / electrode structure in which an electrolyte membrane is disposed between a pair of electrodes is sandwiched by a pair of separators, and is provided on one fuel cell component. A first seal member and a second seal member provided on the other fuel cell constituent member. And while the 1st seal member provides the convex-shaped part which protrudes toward the 2nd seal member, the said 2nd seal member has provided the concave-shaped part which the said convex-shaped part contacts.

  Moreover, it is preferable that a concave part is comprised so that only the front-end | tip of a convex part can be accommodated. This is because the thickness of the second seal member can be easily reduced.

  Furthermore, it is preferable that one fuel cell constituent member is a separator or an electrolyte membrane / electrode structure, and the other fuel cell constituent member is the separator or the electrolyte membrane / electrode structure. The fuel cell constituent member refers to, for example, any of the end plate, the insulating plate, the terminal plate, or all the constituent members in addition to the separator and the electrolyte membrane / electrode structure.

  Furthermore, the fuel cell is preferably mounted on a fuel cell vehicle while laminating a plurality of power generation cells.

  According to the present invention, since the convex portion of the first seal member contacts the concave portion of the second seal member, the frictional force generated between the first and second seal members increases. Accordingly, the sealing performance between the first and second sealing members is improved satisfactorily. For example, even when vibration occurs when the vehicle is mounted, the convex portion and the concave portion are firmly engaged to cause a seal deviation. Can be prevented. This makes it possible to ensure a good sealing function with a simple configuration.

  FIG. 1 is an exploded perspective view of a main part of a power generation cell 12 constituting a fuel cell 10 employing a seal structure according to the first embodiment of the present invention, and FIG. 2 shows a plurality of power generation cells 12 as arrows. FIG. 2 is a cross-sectional explanatory view taken along line II-II in FIG. 1 of the fuel cell 10 stacked in a direction A and stacked.

  As shown in FIG. 2, the fuel cell 10 has a plurality of power generation cells 12 stacked in the direction of arrow A, and end plates 14 a and 14 b are disposed at both ends in the stacking direction. The end plates 14a and 14b are fixed via tie rods (not shown), whereby a predetermined tightening load is applied to the stacked power generation cells 12 in the arrow A direction. The fuel cell 10 is mounted on a fuel cell vehicle (not shown).

  As shown in FIG. 1, in the power generation cell 12, the electrolyte membrane / electrode structure 16 is sandwiched between a first metal separator (fuel cell constituent member) 18 and a second metal separator (fuel cell constituent member) 20. . The first metal separator 18 and the second metal separator 20 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate whose surface has been subjected to anticorrosion treatment, and has a thickness. Is set within a range of 0.05 mm to 1.0 mm, for example.

  The electrolyte membrane / electrode structure 16 includes, for example, a solid polymer electrolyte membrane 22 in which a thin film of perfluorosulfonic acid is impregnated with water, and an anode side electrode 24 and a cathode side electrode 26 that sandwich the solid polymer electrolyte membrane 22. With. The anode side electrode 24 has a smaller surface area than the cathode side electrode 26.

  The anode side electrode 24 and the cathode side electrode 26 include a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles having a platinum alloy supported on the surface are uniformly applied to the surface of the gas diffusion layer. And have. The electrode catalyst layer is bonded to both surfaces of the solid polymer electrolyte membrane 22.

  One end edge of the power generation cell 12 in the direction of arrow B (the horizontal direction in FIG. 1) communicates with each other in the direction of arrow A, which is the stacking direction, and oxidant for supplying an oxidant gas, eg, an oxygen-containing gas An agent gas inlet communication hole 30a, a cooling medium outlet communication hole 32b for discharging a cooling medium, and a fuel gas outlet communication hole 34b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided in the direction of arrow C (vertical direction). Are provided in an array.

  The other end edge of the power generation cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas inlet communication hole 34a for supplying fuel gas, and a cooling medium inlet communication hole for supplying a cooling medium. 32a and oxidant gas outlet communication holes 30b for discharging the oxidant gas are arranged in the direction of arrow C.

  As shown in FIG. 3, the surface 18a of the first metal separator 18 facing the electrolyte membrane / electrode structure 16 communicates with a fuel gas inlet communication hole 34a and a fuel gas outlet communication hole 34b, as will be described later. For example, a fuel gas flow path 36 that extends vertically downward while meandering in the direction of arrow B is provided.

  As shown in FIG. 1, the surface 20a of the second metal separator 20 facing the electrolyte membrane / electrode structure 16 communicates with an oxidant gas inlet communication hole 30a and an oxidant gas outlet communication hole 30b, and is in the direction of arrow B. Thus, an oxidant gas flow path 38 extending vertically downward while meandering is formed. As shown in FIGS. 1 and 2, the surface 18b of the first metal separator 18 and the surface 20b of the second metal separator 20 communicate with the cooling medium inlet communication hole 32a and the cooling medium outlet communication hole 32b. A cooling medium flow path 40 is formed. The cooling medium flow path 40 extends linearly in the direction of arrow B.

  The first seal member 42 is integrated with the surfaces 18a and 18b of the first metal separator 18 by injection molding or the like around the outer peripheral end portion of the first metal separator 18. The first seal member 42 uses, for example, a seal material such as EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, a cushion material, or a packing material. To do.

  As shown in FIG. 2, the first seal member 42 includes a first outer convex seal (convex portion) 44 a having a substantially triangular cross section provided on the surface 18 a in the vicinity of the outer peripheral end of the first metal separator 18. In addition, a first inner convex seal (convex portion) 46a having a substantially triangular cross section is provided inward from the first outer convex seal 44a by a predetermined distance. The first outer convex seal 44a goes around the outer periphery of the electrolyte membrane / electrode structure 16, and the first inner convex seal 46a goes around the outer periphery of the anode side electrode 24 so as to wrap around the electrolyte membrane / electrode structure. Contact the outer peripheral edge of the electrode structure 16.

  As shown in FIG. 3, the first outer convex seal 44a includes the oxidant gas inlet communication hole 30a, the cooling medium outlet communication hole 32b, the fuel gas outlet communication hole 34b, the fuel gas inlet communication hole 34a, and the cooling medium inlet communication hole. 32a and the oxidizing gas outlet communication hole 30b are surrounded. The first inner convex seal 46a surrounds the fuel gas flow path 36, and the outer periphery of the electrolyte membrane / electrode structure 16 is interposed between the first inner convex seal 46a and the first outer convex seal 44a. Ends are arranged (see FIG. 2).

  The first seal member 42 includes a second outer convex seal (convex portion) 44b having a substantially triangular cross section provided on the surface 18b in the vicinity of the outer peripheral end of the first metal separator 18, and this second outer convex. A second inner convex seal (convex portion) 46b having a substantially triangular cross section is provided inward from the cylindrical seal 44b by a predetermined distance (see FIG. 2). As shown in FIG. 1, the second outer convex seal 44b includes an oxidant gas inlet communication hole 30a, a cooling medium outlet communication hole 32b, a fuel gas outlet communication hole 34b, a fuel gas inlet communication hole 34a, and a cooling medium inlet communication hole. 32a and the oxidizing gas outlet communication hole 30b are surrounded. The second inner convex seal 46 b surrounds the cooling medium flow path 40 and communicates the cooling medium inlet communication hole 32 a and the cooling medium outlet communication hole 32 b with the cooling medium flow path 40.

  As shown in FIG. 2, the first and second outer convex seals 44a and 44b are set at substantially the same position across the first metal separator 18, and the first and second inner convex seals 46a and 46b. Are set at substantially the same position across the first metal separator 18.

  The second seal member 50 is integrated with the surfaces 20a, 20b of the second metal separator 20 around the outer peripheral end of the second metal separator 20 by injection molding or the like. The second seal member 50 may be made of the same material as the first seal member 42 or may be made of a different material. The first and second seal members 42 and 50 constitute a seal structure 51 according to the first embodiment.

  The second seal member 50 includes a first flat seal 52 that is integrated with the surface 20 a of the second metal separator 20, and a second flat seal 54 that is integrated with the surface 20 b of the second metal separator 20. As shown in FIGS. 1 and 4, the first flat seal 52 surrounds the periphery of the oxidant gas inlet communication hole 30 a and the oxidant gas outlet communication hole 30 b so as to communicate with the oxidant gas flow path 38. Formed. The second flat seal 54 is formed by communicating the cooling medium inlet communication hole 32 a and the cooling medium outlet communication hole 32 b with the cooling medium flow path 40.

  As shown in FIG. 2, the first flat seal 52 is configured to be shorter than the second flat seal 54. The first flat seal 52 is provided with a concave portion 52a with which the first outer convex seal 44a of the first seal member 42 contacts (see FIGS. 2 and 4). The concave portion 52a is set to have a substantially curved cross section so that only the tip of the first outer convex seal 44a can be accommodated. The first inner convex seal 46 a is in direct contact with the outer peripheral edge portion of the solid polymer electrolyte membrane 22 of the electrolyte membrane / electrode structure 16.

  The second flat seal 54 includes an outer concave portion 54a that contacts a second outer convex seal 44b of a first seal member 42 that constitutes another power generation cell 12, and a second inner convex shape of the first seal member 42. An inner concave portion 54b with which the seal 46b contacts is provided. The outer concave portion 54a and the inner concave portion 54b are set to have a substantially curved cross section so as to accommodate only the tip of the second outer convex seal 44b and only the tip of the second inner convex seal 46b, respectively.

  When the solid polymer electrolyte membrane 22 is configured to have the same dimensions as the anode-side electrode 24, the outer peripheral edge portion of the cathode-side electrode 26 is impregnated with a sealing material, and the first inner convex shape is formed on the outer peripheral edge portion. The seal 46a may be brought into direct contact.

  As shown in FIGS. 1 and 3, the first metal separator 18 has a plurality of passages communicating with the surface 18b provided with the cooling medium flow path 40, respectively, with the fuel gas inlet communication hole 34a and the fuel gas outlet communication hole 34b. 56a and 56b are formed. The passages 56a and 56b communicate with a plurality of holes 58a and 58b, and the holes 58a and 58b communicate with a fuel gas flow path 36 provided on the surface 18a.

  The operation of the fuel cell 10 configured as described above will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 34a. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet communication hole 32a.

  For this reason, the oxidant gas is introduced into the oxidant gas flow path 38 of the second metal separator 20 from the oxidant gas inlet communication hole 30a and moves vertically downward while meandering in the arrow B direction. For this reason, the oxidant gas is supplied to the cathode side electrode 26 constituting the electrolyte membrane / electrode structure 16 (see FIG. 2).

  On the other hand, the fuel gas is introduced into the fuel gas flow path 36 of the first metal separator 18 from the fuel gas inlet communication hole 34a through the passage 56a and the hole 58a (see FIG. 3). This fuel gas moves vertically downward while meandering in the direction of arrow B, and is supplied to the anode side electrode 24 constituting the electrolyte membrane / electrode structure 16 (see FIG. 2).

  Therefore, in each electrolyte membrane / electrode structure 16, the oxidant gas supplied to the cathode side electrode 26 and the fuel gas supplied to the anode side electrode 24 are consumed by an electrochemical reaction in the electrode catalyst layer. Power generation is performed.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 26 is discharged in the direction of arrow A along the oxidant gas outlet communication hole 30b (see FIG. 1). The fuel gas consumed by being supplied to the anode side electrode 24 passes through the hole 58b and the passage 56b and is discharged in the direction of arrow A along the fuel gas outlet communication hole 34b.

  The cooling medium supplied to the cooling medium inlet communication hole 32a is introduced into the cooling medium flow path 40 between the first and second metal separators 18 and 20, and then flows in the arrow B direction. The cooling medium is discharged from the cooling medium outlet communication hole 32b after the electrolyte membrane / electrode structure 16 is cooled.

  In this case, in the first embodiment, as shown in FIG. 2, the first and second seal members 42 and 50 are integrated with the first and second metal separators 18 and 20 constituting the power generation cell 12. In addition, the tip of the first outer convex seal 44 a of the first seal member 42 is accommodated in a concave portion 52 a provided on the first flat seal 52 of the second seal member 50.

  For this reason, in each power generation cell 12, the frictional force generated between the first and second seal members 42, 50 increases, and the sealing performance between the first and second seal members 42, 50 is improved satisfactorily. Thereby, for example, even when vibration or the like occurs when the vehicle is mounted, it is possible to reliably prevent the first outer convex seal 44a and the concave portion 52a from being firmly engaged and causing a seal deviation.

  Furthermore, between the adjacent power generation cells 12, the tips of the second outer convex seal 44 b and the second inner convex seal 46 b provided on the first seal member 42 of one power generation cell 12 are connected to the other power generation cell 12. The second seal member 50 is housed in an outer concave portion 54a and an inner concave portion 54b.

  Accordingly, the second outer convex seal 44b and the second inner convex seal 46b, which are double seals, and the outer concave portion 54a and the inner concave portion 54b can be more firmly engaged than the single seal. Even if vibration or the like is applied when the vehicle is mounted, no deviation occurs between the adjacent power generation cells 12. Thereby, it is possible to obtain an effect that it is possible to ensure a good sealing function and insulating function in the entire fuel cell 10 with a simple configuration.

  Moreover, even if a compressive strain occurs in the first and second seal members 42 and 50 with the thermal change and the passage of time, the contact area between them does not decrease. For this reason, there exists an advantage that a desired sealing function can be maintained.

  FIG. 5 is a partial cross-sectional explanatory view of the power generation cell 72 constituting the fuel cell 70 in which the seal structure according to the second embodiment of the present invention is employed. Note that the same components as those of the power generation cell 12 constituting the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, the detailed description of the third embodiment described below will be omitted.

  The power generation cell 72 is configured by sandwiching an electrolyte membrane / electrode structure (fuel cell constituent member) 74 between first and second metal separators 76 and 78. In the electrolyte membrane / electrode structure 74, the anode side electrode 24 and the cathode side electrode 26 have the same surface area, and the solid polymer electrolyte membrane 22 has a larger surface area than the anode side electrode 24 and the cathode side electrode 26. Have.

  A seal member 80 is integrated with the outer peripheral edge of the solid polymer electrolyte membrane 22 by injection molding or the like. The seal member 80 includes convex seals (convex portions) 82 a and 82 b that protrude toward the first and second metal separators 76 and 78.

  The first and second seal members 84 and 86 are integrated with each other around the outer peripheral ends of the first and second metal separators 76 and 78. The first and second seal members 84 and 86 constitute a flat seal, and concave portions 84a and 86a are formed at portions that contact the convex seals 82a and 82b. The concave portions 84a and 86a are set to have a substantially curved cross section, and accommodate only the tips of the convex seals 82a and 82b, respectively. The seal structure 88 is constituted by the seal member 80 and the first and second seal members 84 and 86.

  In the second embodiment configured as described above, the convex seals 82 a and 82 b of the seal member 80 integrated with the electrolyte membrane / electrode structure 74 are integrated with the first and second metal separators 76 and 78. The first and second seal members 84 and 86 are in contact with the concave portions 84a and 86a. For this reason, the power generation cell 72 has the desired insulation function, does not cause seal deviation, and can ensure a good sealing function especially when mounted on the vehicle, for example, as in the first embodiment. An effect is obtained.

  FIG. 6 is a partial cross-sectional explanatory diagram of a power generation cell 92 constituting a fuel cell 90 in which a seal structure according to a third embodiment of the present invention is employed.

  The power generation cell 92 is configured by sandwiching an electrolyte membrane / electrode structure (fuel cell structural member) 94 between first and second metal separators (fuel cell structural members) 96 and 98. The solid polymer electrolyte membrane 22 constituting the electrolyte membrane / electrode structure 94 has a larger surface area than the anode-side electrode 24 and the cathode-side electrode 26, and the seal member 100 is integrated at the front edge thereof. Is done.

  The first and second seal members 102 and 104 are integrated with the front edge portions of the first and second metal separators 96 and 98, and the first and second seal members 102 and 104 are formed of an electrolyte membrane Convex seals (convex portions) 106a and 106b projecting toward the electrode structure 94 are provided. On both surfaces of the seal member 100, concave portions 100a and 100b having a substantially curved cross section that can accommodate only the tips of the convex seals 106a and 106b are formed, whereby the seal structure 108 is configured.

  In the third embodiment configured as described above, the convex seals 106 a and 106 b of the first and second seal members 102 and 104 are concave portions provided in the seal member 100 of the electrolyte membrane / electrode structure 94. 100a and 100b are contacted, and the same effect as in the first and second embodiments can be obtained.

  In the first to third embodiments, the seal shape has a substantially triangular cross section. However, the present invention is not limited to this. For example, as shown in FIG. A shape may be used. In this case, the convex seal 110 has a curved surface of R1.0 to 3.0 at the tip, while the concave portion 112 in which the tip of the convex seal 110 is accommodated is set corresponding to the tip shape. The

  In the first to third embodiments, the metal plate is used as the separator. However, the present invention is not limited to this. For example, a carbon plate may be used.

It is a principal part disassembled perspective explanatory drawing of the electric power generation cell which comprises the fuel cell by which the seal structure concerning the 1st Embodiment of this invention is employ | adopted. FIG. 2 is a sectional view of the fuel cell taken along line II-II in FIG. 1. It is front explanatory drawing of the 2nd metal separator which comprises the said fuel cell. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is a section explanatory view of the power generation cell which constitutes the fuel cell by which the seal structure concerning a 2nd embodiment of the present invention is adopted. It is a section explanatory view of the power generation cell which constitutes the fuel cell by which the seal structure concerning the 3rd embodiment of the present invention is adopted. It is explanatory drawing of another seal shape. It is explanatory drawing of the seal structure disclosed by patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 70, 90 ... Fuel cell 12, 72, 92 ... Power generation cell 16, 74, 94 ... Electrolyte membrane electrode structure 18, 20, 76, 78, 96, 98 ... Metal separator 22 ... Solid polymer electrolyte membrane 24 ... Anode side electrode 26 ... Cathode side electrode 30a ... Oxidant gas inlet communication hole 30b ... Oxidant gas outlet communication hole 32a ... Cooling medium inlet communication hole 32b ... Cooling medium outlet communication hole 34a ... Fuel gas inlet communication hole 34b ... Fuel gas Outlet communication hole 36 ... Fuel gas flow path 38 ... Oxidant gas flow path 40 ... Cooling medium flow path 42, 50, 80, 84, 86, 100, 102, 104 ... Seal members 44a, 44b ... Outer convex seal 46a, 46b ... Inner convex seal 51, 88, 108 ... Seal structure 52, 54 ... Flat seal 52a, 84a, 86a, 100a, 100b ... Concave portion 54a ... Outer concave Part 54b ... inner recesses 82a, 82b, 106a, 106b ... ridge seal

Claims (4)

A fuel cell seal structure including a power generation cell that sandwiches an electrolyte membrane / electrode structure having an electrolyte membrane disposed between a pair of electrodes with a pair of separators,
A first seal member provided on one fuel cell component;
A second seal member provided on the other fuel cell component;
With
The first seal member is provided with a convex portion that protrudes toward the second seal member, while the second seal member is provided with a concave portion that contacts the convex portion. Seal structure.   2. The fuel cell seal structure according to claim 1, wherein the concave portion is configured to accommodate only a tip of the convex portion. 3. The seal structure according to claim 1 or 2, wherein the one fuel cell constituent member is the separator or the electrolyte membrane / electrode structure,
2. The fuel cell sealing structure according to claim 1, wherein the other fuel cell component is the separator or the electrolyte membrane / electrode structure. The seal structure according to any one of claims 1 to 3, wherein the fuel cell stacks the plurality of power generation cells and is mounted on a fuel cell vehicle.

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