JP2012028194A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably apply an optimum fastening load in a stacking direction of a fuel cell with a compact and lightweight structure.SOLUTION: A fuel cell stack 10 comprises a laminate 14 in which a plurality of fuel cells 12 are stacked, and first and second end plates 20a and 20b are arranged on both ends in a stacking direction of the laminate 14. Corresponding long sides of the first and second end plates 20a and 20b are integrally fixed together via a pair of fastening members 60. The fastening members 60 are each provided with a folded part 62 which is bent in a surface direction of the second end plate 20b so as to be connected to a pressurization adjustment device 22, and a wide-width portion 64 whose width dimension is increased toward the first end plate 20a.

Description

  The present invention includes a fuel cell in which an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a rectangular separator are stacked, and a stacking direction of the stack in which a plurality of the fuel cells are stacked A pair of end plates are disposed at both ends, and the long sides of the pair of end plates relate to a fuel cell stack that is integrally fixed by a fastening member.

  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 disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched by separators. Unit cell (power generation cell). This type of fuel cell is usually used as an in-vehicle fuel cell stack or the like by stacking a predetermined number of unit cells.

  In this type of fuel cell stack, it is necessary to apply a good tightening load to the stacking direction in order to obtain a desired power generation performance and to exert a sealing function.

  For example, as shown in FIG. 6, the fuel cell stack disclosed in Patent Document 1 holds a stacked body in which a plurality of fuel cells 1 are sandwiched between end plates 2 and 3, and a plurality of fastening plates 4. It has. The fastening plate 4 is in contact with the side portion of the laminate, and a bent portion 4a is provided on at least one of the upper portion and the lower portion of the laminate. The bent portion 4 a of the fastening plate 4 is fixed to the end plates 2 and 3 via bolts 5 and nuts 6.

JP 2004-362940 A

  In the above-mentioned Patent Document 1, four rectangular fastening plates 4 are used, and the bent portions 4a that are both ends of each fastening plate 4 are fixed to the center of each side of the end plates 2 and 3. ing. For this reason, stress tends to concentrate on the end plates 2 and 3 at a specific position in the tightening direction (stacking direction). Thereby, distortion etc. arise in the end plates 2 and 3, and there exists a problem that a uniform clamping force cannot be provided to the whole surface (especially whole power generation surface) of a laminated body.

  An object of the present invention is to solve this type of problem, and to provide a fuel cell stack capable of reliably applying an optimum tightening load in the stacking direction of the fuel cells with a small and lightweight configuration. To do.

  The present invention includes a fuel cell in which an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a rectangular separator are stacked, and a stacking direction of the stack in which a plurality of the fuel cells are stacked A pair of end plates are disposed at both ends, and the long sides of the pair of end plates relate to a fuel cell stack that is integrally fixed by a fastening member.

  In this fuel cell stack, one end plate is provided with a pressure adjusting device capable of adjusting a fastening load applied toward the laminated body, and a fastening member is attached to one end portion on the one end plate side. A bent portion that is bent in the surface direction of the one end plate and connected to the pressure adjusting device, and a width dimension toward the other side of the other end plate at the other end portion on the other end plate side And a wide part extending.

  Further, in this fuel cell stack, the fastening member includes a main body portion extending with the same width dimension between the long sides of the pair of end plates, and the other end portion side of the main body portion is provided on the other side. It is preferable that a pair of reinforcing plate portions constituting a wide portion is provided by extending in a direction away from each other toward both ends of the long side of the end plate.

  Further, in this fuel cell stack, the pressure adjusting device includes a load measuring mechanism in which a plurality of load sensors are coupled to one end plate, and a screw hole provided in a bent portion, and the load measuring mechanism is stacked on the laminate. And a pressurizing mechanism having a plurality of load adjustment bolts for applying a fastening load to the laminate through a plurality of load sensors, and the load adjustment bolt includes the fastening member. It is preferable that the load sensor is disposed at a position coaxial with the load sensor.

  According to the present invention, since the pressure adjusting device is connected to the bent portion constituting the fastening member, a dedicated plate for attaching the pressure adjusting device becomes unnecessary. Therefore, the number of parts can be effectively reduced, the size and weight can be reduced, and the configuration can be simplified.

  Moreover, the fastening member has a wide portion at the other end portion on the other end plate side. For this reason, the wide portion and the end plate are connected in a relatively wide range in the long side direction of the end plate, and it is possible to satisfactorily prevent stress from concentrating on the end plate.

  This makes it possible to reliably apply an optimum tightening load in the stacking direction of the fuel cells with a small and lightweight configuration.

1 is a schematic perspective view of a fuel cell stack according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of a main part of the fuel cell stack. It is a partially exploded perspective view of the fuel cell stack. FIG. 4 is a cross-sectional view of the fuel cell stack taken along line IV-IV in FIG. 3. It is a principal part disassembled perspective explanatory drawing of the fuel cell which comprises the said fuel cell stack. 6 is a perspective explanatory view of a fuel cell stack of Patent Document 1. FIG.

  As shown in FIGS. 1 and 2, in the fuel cell stack 10 according to the embodiment of the present invention, a stacked body 14 is configured by stacking a plurality of fuel cells 12 in the direction of arrow A (vertical direction). A first terminal plate 16a, a first insulating plate 18a, and a first end plate (the other end plate) 20a are stacked on the lower end (one end) of the stacked body 14 in the stacking direction.

  As shown in FIGS. 1 to 3, a second terminal plate 16 b, a second insulating plate 18 b, a second end plate (one end plate) 20 b, and a pressurization are provided at the upper end (the other end) of the stacked body 14. The adjusting device 22 is stacked. The pressure adjusting device 22 includes a load measuring mechanism 24 and a pressure mechanism 26. The stacked body 14 may be configured by stacking a plurality of fuel cells 12 in the horizontal direction (arrow B direction or arrow C direction).

  As shown in FIG. 5, the fuel cell 12 includes an electrolyte membrane / electrode structure 30 sandwiched between first and second separators 32 and 34. The first and second separators 32 and 34 are made of, for example, a metal separator such as a steel plate, a stainless steel plate, an aluminum plate, or a plated steel plate, a carbon separator, or the like.

  One end edge of the fuel cell 12 in the direction of arrow B (the horizontal direction in FIG. 5) communicates with each other in the direction of arrow A, which is the stacking direction, and oxidant for supplying an oxidant gas, for example, an oxygen-containing gas An agent gas inlet communication hole 36a and a fuel gas inlet communication hole 38a for supplying a fuel gas, for example, a hydrogen-containing gas, are arranged in an arrow C direction (horizontal direction).

  The other end edge of the fuel cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas outlet communication hole 38b for discharging fuel gas, and an oxidant gas for discharging oxidant gas. The outlet communication holes 36b are arranged in the direction of arrow C.

  A cooling medium inlet communication hole 40a for supplying a cooling medium and a cooling medium outlet communication hole 40b for discharging the cooling medium are provided at both ends of the fuel cell 12 in the arrow C direction.

  An oxidant gas flow path 42 communicating with the oxidant gas inlet communication hole 36a and the oxidant gas outlet communication hole 36b is provided on the surface 32a of the first separator 32 facing the electrolyte membrane / electrode structure 30.

  A fuel gas passage 44 communicating with the fuel gas inlet communication hole 38a and the fuel gas outlet communication hole 38b is provided on the surface 34a of the second separator 34 facing the electrolyte membrane / electrode structure 30.

  A cooling medium that connects the cooling medium inlet communication hole 40a and the cooling medium outlet communication hole 40b between the surface 32b of the first separator 32 and the surface 34b of the second separator 34 that constitute the fuel cells 12 adjacent to each other. A flow path 46 is provided.

  A first seal member 48 is integrally or individually provided on the surfaces 32 a and 32 b of the first separator 32, and a second seal member 50 is integrally formed on the surfaces 34 a and 34 b of the second separator 34. Or it is provided separately.

  The first and second seal members 48 and 50 are, for example, EPDM, NBR, fluoro rubber, silicon rubber, fluorosilicon rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, or acrylic rubber or the like, cushion material, Alternatively, a packing material is used.

  The electrolyte membrane / electrode structure 30 includes, for example, a solid polymer electrolyte membrane 52 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode side electrode 54 and an anode side electrode 56 that sandwich the solid polymer electrolyte membrane 52. With.

  The cathode side electrode 54 and the anode side electrode 56 are formed by uniformly applying a gas diffusion layer made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the gas diffusion layer. An electrode catalyst layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 52.

  As shown in FIGS. 1 and 2, for example, a pair of fastening members 60 are bridged between the first and second end plates 20a, 20b made of aluminum, and the first and second end plates 20a, 20b are spanned. The distance between them is kept constant. For example, the fastening member 60 has a long plate shape made of aluminum, and one fastening member 60 is disposed on each long side of the fuel cell stack 10 (long side of the first and second end plates 20a and 20b). Is done. The fastening member 60 is configured in a bilaterally symmetric shape.

  The fastening member 60 is bent at one end portion on the second end plate 20b side in the surface direction of the second end plate 20b and is connected to the pressure adjusting device 22, specifically, the pressure mechanism 26. 62 and a wide portion 64 having a width dimension extending toward the long side of the first end plate 20a is provided at the other end of the first end plate 20a.

  The fastening member 60 includes a main body portion 66 extending with the same width dimension between the long sides of the first and second end plates 20a and 20b. A pair of reinforcing plate portions 68 constituting the wide portion 64 are provided by extending in a direction away from each other toward both ends of the long side of the one end plate 20a.

  The width of the main body 66 is set to be smaller than the long side dimensions of the first and second end plates 20a and 20b, and the width center of the main body 66 is set to the first and second end plates 20a and 20b. It almost coincides with the center of the long side.

  The pair of reinforcing plate portions 68 are inclined in a direction away from each other downward from the lower end edge of the main body portion 66, and the lower end portion of the reinforcing plate portion 68 is interposed between the main plate portion 70 and the horizontal plate portion 70. The lower end portion of the portion 66 is integrally connected. The width dimension of the horizontal plate part 70 is larger than the width dimension of the main body part 66. The main body portion 66 and the pair of reinforcing plate portions 68 are provided with at least one or more ribs 72. Ribs may also be provided between the main body portion 66 and the pair of reinforcing plate portions 68. Further, a rib may be provided between the main body portion 66 and the bent portion 62.

  As shown in FIG. 2, the main body portion 66 and the pair of reinforcing plate portions 68 are provided with screw holes 78 into which screws 76 to be inserted into holes 74 formed on the long side of the first end plate 20a are screwed. It is fixed to the first end plate 20a via the screw 76. The main body portion 66 and the pair of reinforcing plate portions 68 may be fixed so as to go from the side surface of the first end plate 20a to the bottom surface and to be hooked on the first end plate 20a.

  The bent portion 62 includes a pair (or three or more) of female screw portions 80 extending in the vertical direction. The female screw portions 80 are spaced apart from each other by a predetermined interval, and extend in the vertical direction so that a screw hole 80a is formed therethrough.

  As shown in FIG. 2, the first end plate 20a has an oxidant gas inlet communication hole 36a, a fuel gas inlet communication hole 38a, a cooling medium inlet communication hole 40a, an oxidant gas outlet communication hole 36b, and a fuel gas outlet communication hole. There are provided manifolds 82a to 82f communicating with 38b and the cooling medium outlet communication hole 40b and extending to the outside.

  As shown in FIG. 3, the second end plate 20b is configured in a flat plate shape, and the second end plate 20b has, for example, four cylindrical recesses 84 formed at four locations.

  As shown in FIGS. 3 and 4, the load measuring mechanism 24 includes a pair of connecting members 86 and a load sensor accommodated in the recess 84, for example, a load cell 88. Instead of the pair of connecting members 86, for example, a connecting member (not shown) configured by integrally joining a pair of connecting members into a frame shape may be used.

  A pressing member 90 is attached to the load cell 88, and the pressing member 90 is disposed in the recess 84. A spherical receiving portion 92 is provided on the load cell 88. At both ends of the connecting member 86, spherical concave portions 94 having a spherical bottom surface are provided at positions corresponding to the spherical receiving portions 92 (coaxial positions).

  The pressurizing mechanism 26 includes a plurality of, for example, four load adjustment bolts 96. Each load adjustment bolt 96 is screwed into a screw hole 80 a formed in the female thread portion 80 of the fastening member 60, and each spherical tip portion 96 a is disposed in each spherical recess 94 of the connecting member 86. The center of each load adjustment bolt 96 and the center of each load cell 88 are arranged at coaxial positions. A lock nut 98 is screwed onto the load adjustment bolt 96.

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

  First, as shown in FIG. 5, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 36a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 38a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 40a.

  Therefore, the oxidant gas is introduced into the oxidant gas flow path 42 of the first separator 32 from the oxidant gas inlet communication hole 36a. The oxidant gas is supplied to the cathode side electrode 54 constituting the electrolyte membrane / electrode structure 30 while moving in the arrow B direction.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 44 of the second separator 34 from the fuel gas inlet communication hole 38a. The fuel gas is supplied to the anode side electrode 56 constituting the electrolyte membrane / electrode structure 30 while moving in the direction of arrow B.

  Therefore, in the electrolyte membrane / electrode structure 30, the oxidant gas supplied to the cathode side electrode 54 and the fuel gas supplied to the anode side electrode 56 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 54 is discharged in the direction of arrow A along the oxidant gas outlet communication hole 36b. On the other hand, the fuel gas consumed by being supplied to the anode side electrode 56 is discharged in the direction of arrow A along the fuel gas outlet communication hole 38b.

  The cooling medium supplied to the cooling medium inlet communication hole 40a is introduced into the cooling medium flow path 46 between the first and second separators 32 and 34, and then flows in the direction of arrow C. The cooling medium is discharged from the cooling medium outlet communication hole 40b after the electrolyte membrane / electrode structure 30 is cooled.

  In this case, an initial load is applied to the fuel cell stack 10 in advance when the stack is assembled. As the power generation usage time of the fuel cell stack 10 elapses, the internal seal, for example, the first and second seal members 48 and 50, the solid polymer electrolyte membrane 52, the carbon separator, and the like may sag due to contraction. May occur.

  At that time, in the fuel cell stack 10, the first and second end plates 20 a, 20 b are fixed by the two fastening members 60 while maintaining an integral distance. For this reason, the fastening load of the fuel cell stack 10 decreases as the usage time elapses.

  Therefore, as shown in FIG. 4, when the load adjustment bolt 96 constituting the pressurizing mechanism 26 is screwed into the screw hole 80a of the female screw portion 80 constituting the second end plate 20b, the spherical shape of the load adjustment bolt 96 is obtained. The distal end portion 96a presses the bottom surface of the spherical concave portion 94 of the connecting member 86 toward the laminated body 14 side.

  For this reason, the load cell 88 that is mounted coaxially with the load adjustment bolt 96 on the connecting member 86 presses the second end plate 20b toward the laminated body 14 via the pressing member 90. As a result, a tightening load is applied to the stacked body 14 via the second end plate 20b.

  In this way, by tightening each load adjusting bolt 96, each load cell 88 arranged coaxially with each load adjusting bolt 96 applies a tightening load to the laminate 14 via the second end plate 20b. is doing. Accordingly, each load cell 88 can accurately detect the value of the additional tightening load while applying the additional tightening load to the laminate 14. Further, retightening can be performed while detecting, and a uniform load can be applied in the surface.

  This makes it possible to accurately detect the load distribution in the plane of the stacked body 14, and the pressurizing mechanism 26 ensures that the load distribution applied to the stacked body 14 is in a uniform state in the plane. In addition, the tightening load can be adjusted easily and reliably.

  In this case, in this embodiment, the fastening member 60 is provided with a bent portion 62 that is bent in the surface direction of the second end plate 20 b and connected to the pressurizing mechanism 26 that constitutes the pressurization adjusting device 22. Specifically, the bent portion 62 includes a pair of female screw portions 80 extending in the vertical direction, and a load adjusting bolt 96 constituting the pressurizing mechanism 26 is formed in the screw hole 80 a formed in the female screw portion 80. Is screwed.

  Therefore, there is no need for a dedicated plate for attaching the pressurizing mechanism 26, and the number of parts is reduced, so that the size and weight can be reduced, and the configuration can be simplified.

  Further, each load adjusting bolt 96 constituting the pressurizing mechanism 26 presses the connecting member 86 coaxially with each load cell 88. Therefore, the additional tightening load by each load adjusting bolt 96 is directly transmitted to the load cell 88. For this reason, there is an advantage that the additional tightening load by the load adjusting bolt 96 is transmitted more directly to the laminate 14.

  In addition, the fastening member 60 has a small load acting due to the additional tightening load of the load adjusting bolt 96. Thereby, the rigidity required for the fastening member 60 may be small, and a reduction in size and weight can be easily achieved. In addition, the fastening member 60 is provided with at least one or more ribs 72. Accordingly, the weight of the fastening member 60 is reduced and the strength is easily improved.

  Furthermore, the fastening member 60 is provided with a wide portion 64 whose width is set larger toward the first end plate 20a side at the other end portion on the first end plate 20a side. Accordingly, the wide portion 64 and the first end plate 20a are connected in a relatively wide range in the long side direction of the first end plate 20a, and it is possible to prevent stress from being concentrated on the first end plate 20a. It becomes possible.

  This makes it possible to reliably apply an optimum tightening load in the stacking direction of the fuel cells 12 with a small and lightweight configuration.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Fuel cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulating plate 20a, 20b ... End plate 22 ... Pressure adjusting device 24 ... Load measuring mechanism 26 ... Pressure mechanism 30 ... Electrolyte Membrane / electrode structure 32, 34 ... Separator 36a ... Oxidant gas inlet communication hole 36b ... Oxidant gas outlet communication hole 38a ... Fuel gas inlet communication hole 38b ... Fuel gas outlet communication hole 40a ... Cooling medium inlet communication hole 40b ... Cooling Medium outlet communication hole 42 ... Oxidant gas flow path 44 ... Fuel gas flow path 46 ... Cooling medium flow path 52 ... Solid polymer electrolyte membrane 54 ... Cathode side electrode 56 ... Anode side electrode 60 ... Fastening member 62 ... Bending part 64 ... Wide part 66 ... Main body part 68 ... Reinforcing plate part 70 ... Horizontal plate part 72 ... Rib 76 ... Screw 80 ... Female thread part 80a ... Screw hole 84 ... Part 86 ... connecting member 88 ... the load cell 94 ... spherical recess 96 ... load adjusting bolt 96a ... spherical tip

Claims (3)

Provided with a fuel cell in which an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a rectangular separator are stacked, and at both ends in the stacking direction of the stack in which a plurality of the fuel cells are stacked, A pair of end plates are disposed, and the long sides of the pair of end plates are a fuel cell stack fixed integrally by a fastening member,
One end plate is provided with a pressure adjusting device capable of adjusting the fastening load applied toward the laminate,
The fastening member is bent at one end portion on the one end plate side, bent in the surface direction of the one end plate, and connected to the pressure adjusting device;
A wide width portion having a width dimension extending toward a long side of the other end plate on the other end portion on the other end plate side;
A fuel cell stack characterized by comprising: 2. The fuel cell stack according to claim 1, wherein the fastening member includes a main body portion extending with the same width dimension between the long sides of the pair of end plates.
On the other end side of the main body portion, a pair of reinforcing plate portions constituting the wide portion is provided by extending in directions away from each other toward both ends of the long side of the other end plate. A fuel cell stack. The fuel cell stack according to claim 1 or 2, wherein the pressure adjusting device includes a load measuring mechanism in which a plurality of load sensors are coupled to the one end plate;
A plurality of loads for applying a fastening load to the laminate via the plurality of load sensors by being screwed into a screw hole provided in the bent portion and pressing the load measuring mechanism toward the laminate. A pressurizing mechanism having an adjusting bolt;
With
The fuel cell stack, wherein the load adjustment bolt is disposed at a position coaxial with the load sensor with respect to the fastening member.

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