JP2004207074A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to maintain a required sealing function even if vibration, impact or the like is given from outside, and to aim at simplification of a structure. <P>SOLUTION: The fuel cell 10 has a first sealing member 50 integrated by turning round an outer periphery end part of a first metal separator 18 and has a second sealing member 58 integrated by turning round an outer periphery end part of a second metal separator 20. A spacer part 54 is fitted at the first sealing member 50 turning round a bent end part 52 of the first metal separator 18, and a spacer part 62 is fitted at the second sealing member 58 turning round a bent end part 60 of the second metal separator 20. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell in which an electrolyte / electrode structure in which an electrolyte is disposed between a pair of electrodes and a metal separator are laminated, and a seal member is provided on the metal separator.
[0002]
[Prior art]
For example, a polymer electrolyte fuel cell has an electrolyte (electrolyte membrane) / electrode structure in which an anode electrode and a cathode electrode are provided on both sides of an electrolyte membrane composed of a polymer ion exchange membrane (cation exchange membrane). Is sandwiched between separators. This type of fuel cell is usually used as a fuel cell stack by laminating a predetermined number of electrolyte / electrode structures and separators.
[0003]
In this fuel cell, a fuel gas supplied to the anode electrode, for example, a gas mainly containing hydrogen (hereinafter, also referred to as a hydrogen-containing gas) is obtained by ionizing hydrogen on the electrode catalyst and passing through the electrolyte to the cathode side. Move to the electrode side. The electrons generated during that time are taken out to an external circuit and used as DC electric energy. Since an oxidant gas, for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas) is supplied to the cathode side electrode, hydrogen ions, electrons, And oxygen react to produce water.
[0004]
In this case, in the fuel cell, the fuel gas, the oxidizing gas, and the cooling medium need to flow in a gas-tight (liquid-tight) manner along dedicated channels. Therefore, usually, various seal members are interposed between the electrolyte / electrode structure and the separator. However, when configuring a fuel cell for a vehicle, there is a possibility that the seal member may be significantly deformed due to vibration during traveling, impact at the time of sudden stop or sudden start, and the like. For this reason, a good contact area cannot be secured, and it may be difficult to maintain desired sealing properties.
[0005]
Further, when a metal separator is used, the surface of the metal separator is liable to be deformed, warped, undulated, etc. due to gas pressure. At that time, the sealing member cannot satisfactorily follow the surface change of the metal separator, and there is a problem that the sealing surface pressure with the separator surface required for maintaining a desired sealing function cannot be secured. .
[0006]
Therefore, for example, in the fuel cell of Patent Document 1, as shown in FIG. 8, packings 3 are disposed on both sides of a fuel cell 1 with spacers 2 interposed therebetween, and one side of the cell 1 , A bipolar separator 4 is disposed. A plurality of cells 1 and bipolar separators 4 are stacked to form a stacked body 5, and the stacked body 5 is disposed between flanges 7 via an end separator 6. The flanges 7 are tightened by the bolts 8 to apply a predetermined tightening force to the laminate 5.
[0007]
At this time, the spacer 2 has a thickness which is equal to the cell thickness when the cell 1 is optimally tightened, and has a thickness which does not change even with the tightening force. Thereby, the cell 1 is protected by the spacer 2, and even if the laminate 5 or the like is fastened with a strong force, the current collector does not overtighten, and the cell 1 is not damaged.
[0008]
[Patent Document 1]
JP-A-6-267567 (paragraphs [0010] and [0011], FIG. 3)
[0009]
[Problems to be solved by the invention]
However, in Patent Document 1 described above, only the plate-like spacers 2 are arranged on both sides of the cell 1. For this reason, when an impact force or the like is applied to the fuel cell stack from an oblique direction, for example, there is a problem that a desired sealing function cannot be maintained. In addition, when the bipolar separator 4 is made of a metal separator, the deformation of the bipolar separator 4 cannot be reliably absorbed by the spacer 2, and the sealing performance may be reduced.
[0010]
The present invention solves this kind of problem, and can secure a desired sealing function even when vibration or impact is applied from the outside, and can further simplify the configuration. The purpose is to provide.
[0011]
[Means for Solving the Problems]
In the fuel cell according to the first aspect of the present invention, the electrolyte / electrode structure and the metal separator are alternately stacked, and the metal separator is provided with a seal member. In order to regulate at least the amount of deformation of the seal member or the metal separator, the metal separator is provided with a spacer member which is formed around the metal separator and around the outer peripheral end thereof.
[0012]
Therefore, when, for example, deformation, surface warpage, undulation, or the like occurs due to gas pressure inside the fuel cell, the spacer members provided on each metal separator come into contact with each other. Therefore, it is possible to prevent the metal separator and the seal member from being excessively deformed, and it is possible to exhibit good sealing properties. In addition, by insulating the outer peripheral edge of the metal separator, electrical contact between the metal separators can be satisfactorily prevented.
[0013]
Furthermore, when the fuel cell is used in a vehicle, the spacer members come into contact with each other, so that the frictional force generated between the sealing member and the metal separator due to vibration or impact increases, and the vibration resistance and the resistance to vibration increase. It is possible to improve the impact properties. In addition, the spacer member can receive the load satisfactorily in response to an impact when mounted on a vehicle, and it is possible to prevent the surface pressure of the electrolyte / electrode structure from increasing.
[0014]
In the fuel cell according to claim 2 of the present invention, the spacer member is integrally formed with the seal member, and the spacer member and the seal member are integrated with the metal separator. Thus, a desired sealing function can be reliably maintained with a simple configuration.
[0015]
Furthermore, in the fuel cell according to claim 3 of the present invention, since the bent end is provided at the outer peripheral end of the metal separator, it is possible to enhance the rigidity by reinforcing the outer peripheral end of the metal separator. Become.
[0016]
Furthermore, in the fuel cell according to claim 4 of the present invention, the metal separator includes first and second metal separators, and the spacer members provided on the first and second metal separators are alternately adjacent to each other. Will be arranged. Therefore, it is possible to effectively prevent the first and second metal separators from electrically contacting each other with a simple configuration.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a main part of a fuel cell stack 12 in which the fuel cells 10 are stacked.
[0018]
As shown in FIG. 2, the fuel cell stack 12 has a plurality of fuel cells 10 stacked in the direction of arrow A, and end plates 14a and 14b arranged at both ends in the stacking direction. By fixing the end plates 14a and 14b via tie rods (not shown), a predetermined tightening load is applied to the stacked fuel cells 10 in the direction of arrow A.
[0019]
As shown in FIG. 1, the fuel cell 10 is configured by sandwiching an electrolyte membrane / electrode structure (electrolyte / electrode structure) 16 between first and second metal separators 18 and 20. The first and second metal separators 18 and 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 metal surface has been subjected to a surface treatment for anticorrosion. For example, it is set in the range of 0.05 mm to 1.0 mm.
[0020]
One end of the fuel cell 10 in the direction of arrow B (horizontal direction in FIG. 1) communicates with each other in the direction of arrow A, which is the stacking direction, to oxidize an oxidant gas, for example, an oxygen-containing gas. The agent gas inlet communication hole 30a, the cooling medium outlet communication hole 32b for discharging the cooling medium, and the fuel gas outlet communication hole 34b for discharging the fuel gas, for example, the hydrogen-containing gas, are arranged in the direction of arrow C (vertical direction). Are arranged in a row.
[0021]
At the other end of the fuel cell 10 in the direction of the arrow B, a fuel gas inlet communication hole 34a for supplying a fuel gas and a cooling medium inlet communication hole for supplying a cooling medium are communicated with each other in the direction of the arrow A. 32a and an oxidizing gas outlet communication hole 30b for discharging the oxidizing gas are arranged in the arrow C direction.
[0022]
The electrolyte membrane / electrode assembly 16 includes, for example, a solid polymer electrolyte membrane 36 in which a thin film of perfluorosulfonic acid is impregnated with water, an anode electrode 38 and a cathode electrode sandwiching the solid polymer electrolyte membrane 36. 40. The anode 38 has a larger surface area than the cathode 40.
[0023]
The anode-side electrode 38 and the cathode-side electrode 40 have a gas diffusion layer made of carbon paper or the like, and an electrode catalyst formed by uniformly applying porous carbon particles having a platinum alloy supported on the surface thereof to the surface of the gas diffusion layer. And a layer. The electrode catalyst layers are joined to both surfaces of the solid polymer electrolyte membrane 36 so as to face each other with the solid polymer electrolyte membrane 36 interposed therebetween.
[0024]
On the surface 18a of the first metal separator 18 on the side of the electrolyte membrane / electrode structure 16, for example, a linear oxidizing gas flow path (reactive gas flow path) 42 extending in the direction of arrow B is provided. As shown in FIGS. 1 and 2, a surface 20 a of the second metal separator 20 on the side of the electrolyte membrane / electrode structure 16 communicates with a fuel gas inlet communication hole 34 a and a fuel gas outlet communication hole 34 b, and an arrow B A linear fuel gas flow path (reactive gas flow path) 44 extending in the direction is formed.
[0025]
Between the surface 18b of the first metal separator 18 and the surface 20b of the second metal separator 20, a cooling medium passage 46 communicating with the cooling medium inlet communication hole 32a and the cooling medium outlet communication hole 32b is formed. The cooling medium passage 46 extends linearly in the direction of arrow B.
[0026]
The first seal member 50 is integrated with the surfaces 18 a and 18 b of the first metal separator 18 around the outer peripheral end of the first metal separator 18. The first sealing member 50 uses, for example, a sealing material, a cushion material, or a packing material such as EPDM, NBR, fluorine rubber, silicon rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, or acrylic rubber. I do.
[0027]
As shown in FIGS. 1 to 3, a bent end portion 52 that is bent toward the electrolyte membrane / electrode structure 16 is formed on the outer peripheral end portion of the first metal separator 18. A spacer portion (spacer member) 54 constituting the first seal member 50 is integrated around the bent end portion 52. This spacer portion 54 is set to a predetermined width dimension H1.
[0028]
A first protrusion 56a is provided on the surface 18a of the first metal separator 18 near the spacer portion 54, and the second protrusion 56b is separated from the first protrusion 56a by a predetermined distance inward. Provided. As shown in FIG. 4, the first and second protrusions 56a and 56b surround the oxidizing gas passage 42, and communicate with the oxidizing gas passage 42, the oxidizing gas inlet communication hole 30a and the oxidizing gas outlet. It is formed to communicate with the communication hole 30b.
[0029]
The first and second protrusions 56a and 56b can be selected to have various shapes such as a tapered tip (lip shape), a trapezoidal shape, or a trapezoidal shape. The second protrusion 56b directly contacts the solid polymer electrolyte membrane 36 constituting the electrolyte membrane / electrode structure 16.
[0030]
A third protrusion 56c is provided on the surface 18b of the first metal separator 18 near the spacer portion 54, and the fourth protrusion 56d is spaced inward from the third protrusion 56c by a predetermined distance. Provided. The third and fourth protrusions 56c, 56d have the same shape as the first and second protrusions 56a, 56b.
[0031]
The second seal member 58 is integrated with the surfaces 20 a and 20 b of the second metal separator 20 around the outer peripheral end of the second metal separator 20. The second seal member 58 is made of the same material as the first seal member 50 described above. A bent end portion 60 that is bent in the same direction as the bent end portion 52 of the first metal separator 18 is formed at an outer peripheral end portion of the second metal separator 20, and the second seal member 58 surrounds the bent end portion 60. Are integrated with each other. The spacer portion 62 is set to a predetermined width dimension H2, and a gap H3 is formed between the spacer portions 54 and 62 when the fuel cell stack 12 is configured.
[0032]
On the surface 20a of the second metal separator 20, a first flat portion 64 to which the first protrusion 56a of the first seal member 50 is in close contact is integrated. On the surface 20b of the second metal separator 20, a second flat portion 66, which is longer than the first flat portion 64 and in which the third and fourth protrusions 56c and 56d of the first seal member 50 are in close contact, is integrated. You.
[0033]
As shown in FIG. 2, the first flat portion 64 orbits a position spaced apart from the outer peripheral end of the electrolyte membrane / electrode structure 16 to the outside, while the second flat portion 66 is provided on the anode electrode 38 at a predetermined position. It circles the position where it polymerizes over the range. As shown in FIG. 5, the first flat portion 64 is formed by connecting the fuel gas inlet communication hole 34a and the fuel gas outlet communication hole 34b to the fuel gas flow path 44, while the second flat portion 66 is formed by cooling. It is formed by communicating the medium inlet communication hole 32a and the cooling medium outlet communication hole 32b.
[0034]
The operation of the fuel cell 10 configured as described above will be described below.
[0035]
First, as shown in FIG. 1, a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 34a, and an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 30a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 32a.
[0036]
Therefore, the oxidizing gas is introduced into the oxidizing gas flow path 42 of the first metal separator 18 from the oxidizing gas inlet communication hole 30a, and moves in the direction of arrow B to form the cathode constituting the electrolyte membrane / electrode structure 16. It is supplied to the side electrode 40. On the other hand, the fuel gas is introduced from the fuel gas inlet communication hole 34a into the fuel gas flow path 44 of the second metal separator 20, and moves in the direction of arrow B to the anode electrode 38 constituting the electrolyte membrane / electrode structure 16. Supplied.
[0037]
Therefore, in each electrolyte membrane / electrode structure 16, the oxidizing gas supplied to the cathode 40 and the fuel gas supplied to the anode 38 are consumed by the electrochemical reaction in the electrode catalyst layer, Power generation is performed.
[0038]
Next, the fuel gas supplied to and consumed by the anode 38 is discharged in the direction of arrow A along the fuel gas outlet communication hole 34b. Similarly, the oxidizing gas supplied to the cathode 40 and consumed is discharged in the direction of arrow A along the oxidizing gas outlet communication hole 30b.
[0039]
The cooling medium supplied to the cooling medium inlet communication hole 32a is introduced into the cooling medium flow path 46 between the first and second metal separators 18 and 20, and then flows in the arrow B direction. This cooling medium is discharged from the cooling medium outlet communication hole 32b after cooling the electrolyte membrane / electrode structure 16.
[0040]
In this case, in the present embodiment, the spacer 54 is provided around the outer peripheral end of the first metal separator 18, and the spacer 62 is provided around the outer peripheral end of the second metal separator 20. . The spacers 54 and 62 are separated from each other with a gap H3 when the fuel cell stack 12 is given a predetermined tightening load (see FIG. 2).
[0041]
Therefore, when the first and second metal separators 18 and 20 are deformed, warped or undulated due to the gas pressure inside each fuel cell 10, for example, the spacer portions 54 and 62 come into contact with each other. Therefore, it is possible to prevent the first and second metal separators 18 and 20 and the first and second seal members 50 and 58 from being excessively deformed, and it is possible to exhibit good sealing properties. The effect is obtained.
[0042]
FIG. 6 shows the relationship between the gas pressure and the leak amount in the present embodiment using the spacer portions 54 and 62 (see the solid line) and the conventional structure not using the spacer portions 54 and 62 (see the dotted line). The results are shown.
[0043]
As a result, in the conventional structure that does not use the spacer portions 54 and 62, the gas pressure in the fuel cell 10 increases, so that the first and second metal separators 18 and 20 and the sealing portion are deformed, and the sealing performance is remarkably improved. Dropped. On the other hand, in the present embodiment, since the spacer portions 54 and 62 are in contact with each other, the amount of leak is effectively reduced, and a desired sealing function can be provided.
[0044]
Further, when an impact is generated on the fuel cell stack 12 in the stacking direction, the spacer portions 54 and 62 come into contact with each other and receive a load. That is, as shown in FIG. 7, when the stack tightening load increases, the shared load and the seal shared load of the electrolyte membrane / electrode structure (MEA) 16 increase with a certain relationship.
[0045]
Therefore, when an impact occurs in the fuel cell stack 12, the spacers 54 and 62 come into contact with each other and the load shared by the spacers 54 and 62 increases, so that the load (surface pressure) shared by the electrolyte membrane / electrode structure 16 is increased. Is effectively reduced. Accordingly, there is an advantage that the surface pressure of the electrolyte membrane / electrode structure 16 can be prevented from increasing due to a shock or the like when mounted on a vehicle, and damage to the electrolyte membrane / electrode structure 16 can be effectively reduced.
[0046]
Furthermore, in the present embodiment, the spacer portion 54 is provided integrally with the first sealing member 50 that is integrated around the outer peripheral end of the first metal separator 18, while the outer periphery of the second metal separator 20 is provided. The spacer portion 62 is provided integrally with the second seal member 58 which is integrated around the end. Thus, the configuration of the first and second seal members 50 and 58 can be simplified, and a desired sealing function can be reliably maintained.
[0047]
Moreover, as shown in FIG. 2, the first seal member 50 has first and second protrusions 56 a and 56 b protruding toward the surface 18 a of the first metal separator 18, and also has the surface 18 b of the first metal separator 18. It has third and fourth protrusions 56c and 56d protruding to the sides. At this time, the first protrusion 56a is in close contact with the first flat portion 64 of the second seal member 58, and the second protrusion 56b is in close contact with the solid polymer electrolyte membrane 36 of the electrolyte membrane / electrode structure 16. The third and fourth protrusions 56c and 56d are in close contact with the second flat portion 66 of the second seal member 58.
[0048]
Therefore, the first and second seal members 50 and 58 include a portion where the spacer portions 54 and 62 are in close contact with each other, a portion where the first and third protrusions 56a and 56c are arranged, and a second and fourth protrusion. The load can be received at three places, that is, the portion where the 56b and 56d are arranged. Therefore, even when an impact is applied to the fuel cell stack 12 when the fuel cell stack 12 suddenly starts or stops when the vehicle is mounted on a vehicle, it is possible to reliably support the load and prevent the deterioration of the sealing function as much as possible.
[0049]
In addition, the first and second metal separators 18 and 20 are provided with bent ends 52 and 60 at their outer peripheral ends. Accordingly, the outer peripheral ends of the first and second metal separators 18 and 20 are reinforced and rigidity is improved. For example, even if an external load inclined to the fuel cell stack 12 in the stacking direction acts on the fuel cell stack 12, this external load is Can be reliably supported, and a desired sealing function can be maintained.
[0050]
Further, spacer portions 54 and 62 are provided at outer peripheral ends of the first and second metal separators 18 and 20. Accordingly, by insulating the outer peripheral ends of the first and second metal separators 18 and 20, electrical contact between the first and second metal separators 18 and 20 can be satisfactorily prevented.
[0051]
In the present embodiment, the spacer 54 is integrated with both surfaces 18 a and 18 b around the outer peripheral end of the first metal separator 18, and the both surfaces 20 a and 20 a around the outer peripheral end of the second metal separator 20. Although the spacer portion 62 is integrated with 20b, it is not limited to this. For example, the spacer 54 may be provided only on the surface 18 a of the first metal separator 18, while the spacer 62 may be provided only on the surface 20 b of the second metal separator 20. Further, the spacers 54, 62 are formed separately from the first and second seal members 50, 58, and the spacers 54, 62 are directly attached to the respective bent ends 52, 60 by bonding or the like. You can also.
[0052]
【The invention's effect】
In the fuel cell according to the present invention, the spacer members provided on each metal separator come into contact with each other when, for example, deformation, surface warpage, undulation, or the like occurs due to gas pressure inside the fuel cell. Therefore, it is possible to prevent the metal separator from being excessively deformed, and it is possible to exhibit good sealing properties.
[0053]
Further, when the fuel cell is used in a vehicle, the frictional force against external vibrations and impacts is increased, and the vibration resistance and impact resistance can be improved. In addition, the spacer member can receive the load satisfactorily with respect to vibration, impact, or the like when mounted on a vehicle, and the surface pressure of the electrolyte / electrode structure can be prevented from increasing.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a main part of a fuel cell according to an embodiment of the present invention.
FIG. 2 is an explanatory sectional view of a main part of a fuel cell stack in which the fuel cells are stacked.
FIG. 3 is a partially sectional perspective view of the fuel cell.
FIG. 4 is an explanatory front view of a first metal separator constituting the fuel cell.
FIG. 5 is an explanatory front view of a second metal separator constituting the fuel cell.
FIG. 6 is an explanatory diagram showing a relationship between a gas pressure and a leak amount depending on the presence or absence of a spacer portion.
FIG. 7 is an explanatory diagram of a stack tightening load and a shared load.
FIG. 8 is an exploded perspective view of a fuel cell according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Fuel cell stack 16 ... Electrolyte membrane / electrode structure 18, 20 ... Metal separator 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 ... solid polymer electrolyte membrane 38 ... anode side electrode 40 ... cathode side electrode 42 ... oxidant gas flow path 44 ... fuel gas flow path 50, 58 ... seal members 52 and 60 ... bent end portions 54 and 62 ... spacer portions 56a to 56d ... protruding portions 64 and 66 ... plane portions

Claims (4)

An electrolyte / electrode structure in which an electrolyte is disposed between a pair of electrodes, and a metal separator are alternately laminated, and a fuel cell in which a seal member is provided on the metal separator,
A fuel cell, wherein a spacer member is provided on the metal separator so as to surround at least an outer peripheral end of the metal separator in order to regulate at least a deformation amount of the seal member or the metal separator. 2. The fuel cell according to claim 1, wherein the spacer member is formed integrally with the seal member, and the spacer member and the seal member are integrated with the metal separator. 3. The fuel cell according to claim 1, wherein a bent end is provided at an outer peripheral end of the metal separator. 4. The fuel cell according to claim 1, wherein the metal separator includes first and second metal separators, and the spacer members provided on the first and second metal separators are adjacent to each other. 5. A fuel cell, wherein the fuel cells are alternately arranged.

Images