JP2005243286A - Fuel cell stack - Google Patents

Abstract

It is possible to apply a desired tightening load to the power generation unit of each single cell and the periphery of the power generation unit, and to simplify the drainage structure.
A fuel cell stack includes a stacked body in which a plurality of single cells are stacked, and an insulating thickness adjusting spacer member is interposed between the stacked body and an end plate. Is done. The spacer member 22 can be moved forward and backward separately from the inner spacer 60 facing the power generation portion 47a and the inner spacer 60 facing the manifold portion 47b, and the outer spacer 62 in which drain hole portions 66a and 66b are formed. With.
[Selection] Figure 5

Description

  The present invention comprises a single cell that sandwiches an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte with a pair of metal separators each having a reaction gas flow path having a concavo-convex shape in cross section. The present invention relates to a stacked fuel cell stack.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. In this fuel cell, an electrolyte membrane / electrode structure comprising an anode catalyst and a cathode electrode composed of an electrode catalyst and porous carbon is provided on both sides of a solid polymer electrolyte membrane, and a separator (bipolar plate) Is pinched by.

  In this fuel 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.

  Normally, this fuel cell is used as a fuel cell stack in which a predetermined number (for example, several tens to several hundreds) is stacked in order to obtain a desired power generation. In this fuel cell stack, it is necessary to pressurize and hold the stacked fuel cells in order to prevent an increase in the internal resistance of the fuel cell and a decrease in the sealing performance of the reaction gas.

  In this case, the fuel cell includes a power generation unit provided in the central portion and a manifold unit that seals a communication hole provided around the power generation unit, and each of the power generation unit and the manifold unit is optimal. Tightening load is different. For this reason, for example, as disclosed in Patent Document 1, a solid height provided with a first fastening means for fastening the region where the manifold portion is located and a second fastening means for fastening the region where the power generation portion is located. Molecular fuel cells are known.

  Specifically, as shown in FIG. 6, the fuel cell of Patent Document 1 includes a fuel cell stack 2 in which a plurality of single cells 1 are stacked, and the fuel cell stack 2 has both ends in the stacking direction. End plates 3 and 4 are arranged. The end plates 3 and 4 are sandwiched between fastening plates 5 a and 5 b, and the fastening plates 5 a and 5 b are fastened in the stacking direction by bolts 6.

  The end plate 4 is configured to be separated from a central plate portion 4a facing the power generation portion and a frame-shaped plate portion 4b facing the manifold portion. The frame-shaped plate portion 4b applies a tightening force to the manifold portion by a tightening force applied between the tightening plates 5a and 5b via the bolt 6, while the central plate portion 4a is disposed on the tightening plate 5b. A tightening force is applied to the power generation unit through a plurality of bolts 7. Therefore, the power generation unit and the manifold unit can apply appropriate tightening forces.

JP-A-8-88018 (FIG. 3)

  However, in Patent Document 1 described above, a plurality of bolts 7 arranged on the fastening plate 5b must be adjusted in order to give a desired fastening force to the power generation unit, and the adjustment work for each bolt 7 is considerable. However, it is complicated and the workability is lowered. Furthermore, it is disclosed that a plurality of disc springs, adjustment plates, bellows, or the like is used in place of the bolt 7, but there is a problem that the number of parts increases and the length is increased in the stacking direction.

  Moreover, the center plate part 4a and the frame-shaped board part 4b which comprise the end plate 4 have electroconductivity. For this reason, when drain holes are formed in the frame-like plate portion 4b in order to discharge water generated in the manifold portion, there is a possibility that a short circuit is caused by the generated water. As a result, for example, a drain hole must be formed in the frame-like plate portion 4b, and an insulating grommet must be attached to the drain hole, which reduces the assembly workability of the fuel cell and is not economical. There is.

  The present invention solves this type of problem, and it is possible to easily and economically configure the drainage structure while applying a desired tightening load to the power generation section of each single cell and the periphery of the power generation section. An object of the present invention is to provide a simple fuel cell stack.

  The present invention comprises a single cell sandwiching an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte with a pair of metal separators each having a concavo-convex reaction gas flow path, the single cell comprising a central cell A fuel cell stack in which a plurality of single cells are stacked while a power generation unit is provided at a portion, a manifold unit including a reaction gas communication hole that flows at least a reaction gas in the stacking direction is provided around the power generation unit .

  The fuel cell stack includes an insulating thickness adjusting spacer member disposed at least on one end side in the stacking direction of the single cells. The thickness adjusting spacer member includes an inner spacer facing the power generation unit, and a manifold unit. The outer spacer is provided separately from the inner spacer so as to be capable of advancing and retreating, and having a drain opening communicating with the reaction gas communication hole for draining.

  An end plate is disposed adjacent to the outer spacer, and a drain hole portion communicating with a drain opening formed in the outer spacer is formed in the end plate, and the drain hole portion is insulated. It is preferable that a sex grommet is attached.

  Furthermore, it is preferable to provide a box-shaped casing that houses a stacked body in which a plurality of single cells are stacked.

  In the present invention, a desired tightening load can be applied to the power generation unit and the manifold unit via the inner spacer and the outer spacer, and reliability and durability can be improved with a simple and small configuration. become. Moreover, since an insulating outer spacer is used, even if generated water adheres to the drain opening formed in the outer spacer, there is no short circuit. Thereby, for example, it is not necessary to attach an insulating grommet to the drain opening, and the number of parts can be reduced, which is economical.

  FIG. 1 is a partially exploded schematic perspective view of a fuel cell stack 10 according to an embodiment of the present invention, FIG. 2 is a schematic perspective view of the fuel cell stack 10, and FIG. It is a partial cross section side view.

  As shown in FIG. 1, the fuel cell stack 10 includes a stacked body 14 in which a plurality of single cells 12 are stacked in the horizontal direction (arrow A direction). A terminal plate 16a, an insulating plate 18 and an end plate 20a are sequentially disposed at one end in the stacking direction (arrow A direction) of the stacked body 14 toward the outside.

  At the other end in the stacking direction of the stacked body 14, a terminal plate 16b, an insulating thickness adjusting spacer member 22 and an end plate 20b are sequentially disposed outward. The fuel cell stack 10 is integrally held by a box-shaped casing 24 including end plates 20a and 20b each having a rectangular shape as end plates.

  As shown in FIG. 1, terminal portions 26a and 26b extending outward in the stacking direction are provided at substantially the center of the terminal plates 16a and 16b. The terminal portions 26a and 26b are inserted into the insulating cylinders 28a and 28b and project outside the end plates 20a and 20b (see FIG. 3). The terminal plate 16b is accommodated in a rectangular opening 29 formed in the spacer member 22 (see FIG. 1).

  As shown in FIGS. 3 and 4, each single cell 12 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 30, and first and second metal separators that sandwich the electrolyte membrane / electrode structure 30. 32, 34. The first and second metal separators 32 and 34 have a concavo-convex shape by pressing a metal thin plate into a wave shape, a dimple shape, or the like.

  An oxidant gas supply for supplying an oxidant gas, for example, an oxygen-containing gas, to one end edge of the long side direction of the single cell 12 (the arrow B direction in FIG. 4) in communication with the arrow A direction. A communication hole 36a, a cooling medium supply communication hole 38a for supplying a cooling medium, and a fuel gas discharge communication hole 40b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided.

  The other end edge in the long side direction of the single cell 12 communicates with each other in the direction of the arrow A, the fuel gas supply communication hole 40a for supplying fuel gas, and the cooling medium discharge communication hole for discharging the cooling medium. 38b and an oxidizing gas discharge communication hole 36b for discharging the oxidizing gas are provided.

  The electrolyte membrane / electrode structure 30 includes, for example, a solid polymer electrolyte membrane 42 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 44 and a cathode side electrode 46 that sandwich the solid polymer electrolyte membrane 42. With.

  The anode side electrode 44 and the cathode side electrode 46 are composed of a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles carrying a platinum alloy 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 42.

  In the single cell 12, a power generation unit 47a including the anode side electrode 44 and the cathode side electrode 46 is provided in the central portion, and a manifold unit 47b for flowing an oxidant gas, a fuel gas, and a cooling medium is provided around the power generation unit 47a. It is done.

  A fuel gas flow path 48 that connects the fuel gas supply communication hole 40 a and the fuel gas discharge communication hole 40 b is formed on the surface 32 a of the first metal separator 32 facing the electrolyte membrane / electrode structure 30. The fuel gas channel 48 is constituted by, for example, a plurality of grooves extending in the arrow B direction. On the surface 32b of the first metal separator 32, a cooling medium flow path 50 that connects the cooling medium supply communication hole 38a and the cooling medium discharge communication hole 38b is formed. The cooling medium flow path 50 is configured by a plurality of grooves extending in the arrow B direction.

  The surface 34a of the second metal separator 34 facing the electrolyte membrane / electrode structure 30 is provided with, for example, an oxidant gas flow path 52 composed of a plurality of grooves extending in the direction of arrow B, and this oxidant gas. The flow path 52 communicates with the oxidant gas supply communication hole 36a and the oxidant gas discharge communication hole 36b. A cooling medium flow path 50 is integrally formed on the surface 34 b of the second metal separator 34 so as to overlap the surface 32 b of the first metal separator 32.

  A first seal member 54 is integrally formed on the surfaces 32 a and 32 b of the first metal separator 32 around the outer peripheral end of the first metal separator 32. The first seal member 54 surrounds the fuel gas supply communication hole 40a, the fuel gas discharge communication hole 40b, and the fuel gas flow path 48 on the surface 32a so as to communicate with each other, and on the surface 32b, the cooling medium supply communication hole 38a, The medium discharge communication hole 38b and the cooling medium flow path 50 are surrounded and communicated with each other. The first seal member 54 has a convex portion 55a on the surface 32a and a convex portion 55b on the surface 32b.

  A second seal member 56 is integrally formed on the surfaces 34 a and 34 b of the second metal separator 34 around the outer peripheral end of the second metal separator 34. The second seal member 56 surrounds and communicates the oxidant gas supply communication hole 36a, the oxidant gas discharge communication hole 36b, and the oxidant gas flow path 52 on the surface 34a, while the cooling medium supply communication hole on the surface 34b. 38a, the cooling medium discharge communication hole 38b, and the cooling medium flow path 50 are surrounded and communicated. The second seal member 56 has a convex portion 58 on the surface 34a.

  As shown in FIGS. 1 and 5, the spacer member 22 includes an inner spacer 60 that faces the power generation portion 47 a and an outer spacer 62 that faces the manifold portion 47 b and can be advanced and retracted separately from the inner spacer 60. . The inner spacer 60 and the outer spacer 62 are made of an insulating material such as polycarbonate (PC) or phenol resin.

  The inner spacer 60 is configured in a frame shape, provided with a rectangular opening 29, and the terminal plate 16 b is accommodated in the opening 29. The outer spacer 62 is formed in a frame shape, and drain openings 64a and 64b are formed to communicate with the oxidant gas discharge communication hole 36b and the fuel gas discharge communication hole 40b to drain water.

  As will be described later, the thickness T1 of the inner spacer 60 and the thickness T2 of the outer spacer 62 are obtained by respectively obtaining the stack height when a set load is applied to the power generation section 47a and the manifold section 47b. It is set from the dimensional difference of the stack height.

  The end plate 20b is formed with drain holes 66a and 66b communicating with the drain openings 64a and 64b. The drain holes 66a and 66b are provided with insulating grommets 68a and 68b.

  As shown in FIG. 1, the casing 24 includes end plates 20 a and 20 b that are end plates, a plurality of side plates 70 a to 70 d disposed on the side of the laminated body 14, and end portions of the side plates 70 a to 70 d that are close to each other. Angle members (for example, L angles) 72a to 72d that connect the portions, and connecting pins 74a and 74b that connect the end plates 20a and 20b and the side plates 70a to 70d, respectively, having different lengths.

  Two first connection portions 76a and 76b are formed to protrude from the upper and lower sides of the end plates 20a and 20b, respectively, and one first connection portion 76c and 76d is formed to protrude from each side of each side. The Mount boss portions 78a and 78b are formed at the lower ends of the sides of the end plates 20a and 20b. The boss portions 78a and 78b are fixed to mounting portions (not shown) via bolts or the like, so that the fuel cell stack 10 is mounted on, for example, a vehicle.

  Two second connecting portions 80a and 80b are formed at both ends in the longitudinal direction of the side plates 70a and 70c arranged on both sides in the lateral direction of the laminated body 14, respectively. Three second connecting portions 82a and 82b are formed at both ends in the longitudinal direction of the side plates 70b and 70d disposed on both the upper and lower sides of the laminated body 14, respectively.

  Between the second connecting portions 80a and 80b of the side plates 70a and 70c, first connecting portions 76c and 76d on both sides of the end plates 20a and 20b are arranged, and a short connecting pin 74a is integrally formed therewith. The side plates 70a and 70c are attached to the end plates 20a and 20b.

  Similarly, the second connecting portions 82a and 82b of the side plates 70b and 70d are alternately arranged with the first connecting portions 76a and 76b on the upper and lower sides of the end plates 20a and 20b, and a long connecting pin 74b is provided on these. The side plates 70b and 70d are attached integrally to the end plates 20a and 20b.

  In the side plates 70a to 70d, a plurality of screw holes 84 are formed at both edges in the short direction, respectively, while holes 86 are formed on the sides of the angle members 72a to 72d corresponding to the screw holes 84, respectively. Is done. When the screws 88 inserted into the holes 86 are screwed into the screw holes 84, the side plates 70a to 70d are fixed to each other via the angle members 72a to 72d. Thereby, the casing 24 is configured (see FIG. 2).

  While the screw holes are formed in the angle members 72a to 72d, the holes are formed in the side plates 70a to 70d, and the angle members 72a to 72d are disposed inward of the side plates 70a to 70d, and these are integrated. Alternatively, it may be screwed.

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

  First, as shown in FIG. 2, in the fuel cell stack 10, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 36a of the end plate 20a, and hydrogen is contained in the fuel gas supply communication hole 40a. Fuel gas such as gas is supplied. Further, a coolant such as pure water or ethylene glycol is supplied to the coolant supply passage 38a. For this reason, in the laminated body 14, oxidant gas, fuel gas, and a cooling medium are each supplied to the some cell 12 piled up by the arrow A direction at the arrow A direction.

  As shown in FIG. 4, the oxidant gas is introduced into the oxidant gas flow path 52 of the second metal separator 34 through the oxidant gas supply communication hole 36 a, and along the cathode side electrode 46 of the electrolyte membrane / electrode structure 30. Move. On the other hand, the fuel gas is introduced into the fuel gas passage 48 of the first metal separator 32 through the fuel gas supply communication hole 40 a and moves along the anode side electrode 44 of the electrolyte membrane / electrode structure 30.

  Therefore, in each electrolyte membrane / electrode structure 30, the oxidant gas supplied to the cathode side electrode 46 and the fuel gas supplied to the anode side electrode 44 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed (see FIG. 3).

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 46 flows along the oxidant gas discharge communication hole 36b, and then is discharged to the outside from the end plate 20a. Similarly, the fuel gas consumed by being supplied to the anode side electrode 44 is discharged to the fuel gas discharge communication hole 40b, flows, and is discharged from the end plate 20a to the outside.

  The cooling medium flows in the direction of arrow B after being introduced into the cooling medium flow path 50 between the first and second metal separators 32 and 34 from the cooling medium supply communication hole 38a. The cooling medium cools the electrolyte membrane / electrode structure 30, and then moves through the cooling medium discharge communication hole 38b and is discharged from the end plate 20a.

  In this case, in this embodiment, as shown in FIGS. 1 and 5, the spacer member 22 is disposed in the vicinity of the end plate 20 b, and the spacer member 22 faces the power generation unit 47 a of the single cell 12. An inner spacer 60 is provided, and an outer spacer 62 is provided so as to face the manifold portion 47b provided around the power generation portion 47a and can be moved forward and backward separately from the inner spacer 60.

  For this reason, a desired tightening load can be individually applied to the power generation unit 47 a and the manifold unit 47 b via the inner spacer 60 and the outer spacer 62.

  Specifically, first, only a measurement spacer (not shown) is installed facing the power generation unit 47a, and the set height of the power generation unit 47a is applied to the fuel cell stack 10 to measure the stack height. Next, a measurement spacer (not shown) is installed only in the manifold portion 47b, and a set load of the manifold portion 47b is applied to the fuel cell stack 10 to measure the stack height.

  Furthermore, from these dimensional differences, the thicknesses T1 and T2 of the inner spacer 60 and the outer spacer 62 that are the differences may be set, and these may be accommodated in the fuel cell stack 10. As a result, it is possible to maintain a desired power generation function in the power generation section 47a and to set a favorable surface pressure in the manifold section 47b.

  Moreover, in this embodiment, the spacer member 22 need only be accommodated in the casing 24. Accordingly, parts such as a spacer adjusting bolt, a disc spring, an adjusting plate, or a bellows are not required, and the number of parts can be reduced, which is advantageous in that it is economical.

  Further, the outer spacer 62 is formed with drain openings 64a and 64b for draining generated water and condensed water in communication with the oxidant gas discharge communication hole 36b and the fuel gas discharge communication hole 40b. The spacer 62 is made of an insulating material.

  For this reason, even if the generated water of the drain openings 64a and 64b adheres to the outer spacer 62, there is no short circuit, and there is no need to install, for example, an insulating grommet as an insulating structure on the drain openings 64a and 64b. . Thereby, in this embodiment, while the structure of the spacer member 22 is simplified at a stretch, the effect that this spacer member 22 can be comprised economically and small is acquired.

1 is a partially exploded schematic perspective view of a fuel cell stack according to an embodiment of the present invention. 2 is a schematic perspective view of the fuel cell stack. FIG. It is a partial cross section side view of the said fuel cell stack. It is a principal part disassembled perspective view of the single cell which comprises the said fuel cell stack. It is principal part sectional drawing of the said fuel cell stack. 2 is a partial cross-sectional explanatory view of a fuel cell of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Single cell 14 ... Laminated body 16a, 16b ... Terminal plate 18 ... Insulating plate 20a, 20b ... End plate 22 ... Spacer member 24 ... Box-shaped casing 29 ... Opening 30 ... Electrolyte membrane and electrode structure 32, 34 ... Metal separator 42 ... Solid polymer electrolyte membrane 44 ... Anode side electrode 46 ... Cathode side electrode 47a ... Power generation part 47b ... Manifold part 48 ... Fuel gas flow path 50 ... Cooling medium flow path 52 ... Oxidant gas flow path 54, 56 ... Sealing member 60 ... Inner spacer 62 ... Outer spacer 64a, 64b ... Drain opening 66a, 66b ... Drain hole 68a, 68b ... Insulation grommet 70a-70b ... Side plate 72a-72d ... Angle member 74a, 74b ... Connection pin

Claims (3)

Provided with a single cell sandwiching an electrolyte / electrode structure provided with electrodes on both sides of the electrolyte with a pair of metal separators each having a cross-sectional concavo-convex reaction gas flow path, the single cell having a power generation unit at the center A fuel cell stack in which a plurality of single cells are stacked, and a manifold portion including a reaction gas communication hole that flows at least a reaction gas in the stacking direction is provided around the power generation section,
An insulating thickness adjusting spacer member disposed at least on one end side in the stacking direction of the single cells;
The thickness adjusting spacer member includes an inner spacer facing the power generation unit,
An outer spacer that is capable of moving forward and backward separately from the inner spacer facing the manifold portion, and that is formed with a drain opening that communicates with the reaction gas communication hole and drains water,
A fuel cell stack, comprising: The fuel cell stack according to claim 1, wherein an end plate is disposed adjacent to the outer spacer,
The fuel cell stack, wherein the end plate is formed with a drain hole communicating with the drain opening formed in the outer spacer, and an insulating grommet is attached to the drain hole. 3. The fuel cell stack according to claim 1, further comprising a box-shaped casing that accommodates a stacked body in which a plurality of the single cells are stacked. 4.

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