JP2004303472A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent a layered product from being bent by a simple structure, and to secure a desired sealing property. <P>SOLUTION: A middle plate 22 is installed in a layered product 14 with a plurality of unit cells 12 stacked. The middle plate 22 is supported and fixed in parallel with end plates 20a and 20b by interposing a parallel support mechanism 60. The support mechanism 60 is equipped with six fastening bolts 62 for penetrating the middle plate 22 to fasten the end plates 20a and 20b to each other, and insulating collar members 64a and 64b overlaid on the fastening bolts 62 for catching both surfaces of the middle plate 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell stack in which a plurality of electrolyte / electrode structures each having electrodes provided on both sides of an electrolyte are stacked via a separator.
[0002]
[Prior art]
In recent years, various fuel cells have been developed, and for example, a polymer electrolyte fuel cell is known. This polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) composed of a polymer ion exchange membrane (cation exchange membrane). On both sides of the electrolyte membrane, an electrolyte membrane / electrode structure (electrolyte / electrode structure) in which an anode electrode and a cathode electrode made of an electrode catalyst and porous carbon are opposed to each other is sandwiched by a separator (bipolar plate). Form a unit cell.
[0003]
In a fuel cell of this type, a fuel gas supplied to the anode side electrode, for example, a gas mainly containing hydrogen (hereinafter, also referred to as a hydrogen-containing gas) is obtained by ionizing hydrogen on an electrode catalyst and passing through an electrolyte. It moves to the cathode side 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]
Usually, this fuel cell is used as a fuel cell stack in which a predetermined number of fuel cells are stacked in order to obtain a desired power generation. However, a shape error easily exists in the electrolyte membrane / electrode structure and the separator constituting each fuel cell, and the shape errors are accumulated by stacking a large number of fuel cells. For this reason, it has been pointed out that a stacked body in which a large number of fuel cells are stacked is bent in the stacking direction as a whole, and the sealing performance of the reaction gas is reduced.
[0005]
In order to suppress the bending of the stack in the stacking direction, for example, a fuel cell stack disclosed in Patent Document 1 is known. As shown in FIG. 7, the fuel cell stack includes a stacked body 2 in which a plurality of unit cells 1 are stacked in the direction of arrow X. End plates 3 are provided at both ends of the stacked body 2. An intermediate plate 4 is interposed in the middle of the stacked body 2, and a stud bolt 5 is provided through the stacked body 2 and the intermediate plate 4. The stud bolt 5 is formed with a large-diameter flange portion 5a. The flange portion 5a fits into the stepped hole portion 4a of the intermediate plate 4 and moves in a direction (arrow Y direction) orthogonal to the laminating direction. Be regulated. A backup plate 7 is laminated on one end plate 2 with a disc spring 6 interposed therebetween.
[0006]
In this Patent Document 1, an intermediate plate 4 is provided at an intermediate position in the stacking direction of the stacked body 2, and the stacked body 2 is divided on both sides of the intermediate plate 4. Therefore, the stacked body 2 can substantially suppress the shape error accumulated in the thickness direction to about half.
[0007]
[Patent Document 1]
JP-A-2002-151135 (paragraphs [0023] to [0025], FIGS. 3 and 5)
[0008]
[Problems to be solved by the invention]
By the way, it is difficult for the intermediate plate 4 arranged in the laminate 2 to maintain the parallelism with respect to one end plate 3. For this reason, the unit cells 1 stacked on the intermediate plate 4 may accumulate the shape error of each unit cell 1 and may bend in the stacking direction as a whole.
[0009]
In particular, when the separator of the unit cell 1 is formed of a metal separator, the separator itself is often deformed due to processing such as pressing. Thus, even when the number of stacked unit cells 1 is relatively small, there is a concern that the unit cells 1 may bend in the stacking direction.
[0010]
Further, when the fuel cell stack is used for mounting on a vehicle, the stack 2 may move in the stacking direction when the vehicle suddenly starts or suddenly brakes. This is because the disc spring 6 is interposed between the end plate 3 and the backup plate 7. For this reason, a gap may be generated between the unit cells 1, and the sealing performance of the reaction gas may be reduced.
[0011]
The present invention solves this kind of problem, and an object of the present invention is to provide a fuel cell stack that can reliably prevent bending of a stacked body and secure a desired sealing property with a simple configuration. And
[0012]
[Means for Solving the Problems]
The fuel cell stack according to claim 1 of the present invention includes a unit cell in which an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte is sandwiched between separators, and a stack is formed by stacking a plurality of the unit cells. In addition, end plates are provided at both ends in the stacking direction of the stacked body.
[0013]
A predetermined position in the stacking direction, that is, an intermediate plate corresponding to a predetermined number of unit cells is disposed in the stack, and the intermediate plates are mutually moved with respect to the end plate via a parallel support mechanism. It is supported and fixed in parallel.
[0014]
In this manner, the intermediate plate is supported in parallel with the end plate and disposed in the laminate, so that the laminate is divided into a predetermined number of unit cells, and the shape error of each unit cell is accumulated, and There is no possibility that the laminate is inclined in the laminating direction. Therefore, the surface pressure in the laminate can be maintained uniform, and the contact resistance in the laminate can be reduced with a simple configuration.
[0015]
In addition, since the intermediate plate is fixed between the end plates, for example, when used for a vehicle, the stacked body does not move in the stacking direction when the vehicle suddenly starts or suddenly brakes. Accordingly, a relatively large gap is not generated between the unit cells, a desired sealing property can be secured, and the power generation performance can be easily improved.
[0016]
Further, in the fuel cell stack according to claim 2 of the present invention, the parallel support mechanism penetrates the intermediate plate to fasten the end plates and fastens between the end plates, and is externally mounted on the fastening bolt and sandwiches both surfaces of the intermediate plate. A collar member. For this reason, the structure of the parallel support mechanism can be simplified, and the position of the intermediate plate is regulated by the collar member, so that the tightening load acting on the laminate can be appropriately adjusted.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic overall perspective view of a fuel cell stack 10 according to a first embodiment of the present invention, and FIG. 2 is a partial cross-sectional side view of the fuel cell stack 10.
[0018]
The fuel cell stack 10 includes a stacked body 14 in which a plurality of unit cells 12 are stacked in the direction of arrow A. At both ends of the stacked body 14 in the stacking direction (direction of arrow A), terminal terminal plates 16a and 16b, and insulators The plates 18a and 18b and the end plates 20a and 20b are sequentially arranged outward. An intermediate plate 22 is provided in the laminate 14 at a predetermined position in the laminating direction, for example, at an intermediate position of the laminate 14.
[0019]
As shown in FIG. 3, each unit cell 12 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 24, and first and second separators 26 and 28 sandwiching the electrolyte membrane / electrode structure 24. Is provided. The first and second separators 26 and 28 are made of, for example, a metal plate. Note that the first and second separators 26 and 28 may be made of a carbon material or the like.
[0020]
An oxidizing gas supply passage 30a for supplying an oxidizing gas, for example, an oxygen-containing gas, is connected to one end edge of the unit cell 12 in the long side direction (the direction of the arrow B) in the direction of the arrow A. And a fuel gas discharge communication hole 32b for discharging a fuel gas, for example, a hydrogen-containing gas.
[0021]
The other end of the unit cell 12 in the long side direction communicates with each other in the direction of arrow A to provide a fuel gas supply passage 32a for supplying fuel gas, and an oxidizing gas for discharging oxidizing gas. A discharge communication hole 30b is provided.
[0022]
At one edge of the unit cell 12 in the short side direction (direction of arrow C), two cooling medium supply communication holes 34a for supplying a cooling medium are provided, and the other end of the unit cell 12 in the short side direction is provided. Two cooling medium discharge communication holes 34b for discharging the cooling medium are provided at the edge.
[0023]
The electrolyte membrane / electrode structure 24 includes, for example, a solid polymer electrolyte membrane 36 in which a thin film of perfluorosulfonic acid is impregnated with water, an anode 38 and a cathode 40 sandwiching the solid polymer electrolyte 36. And
[0024]
The anode electrode 38 and the cathode electrode 40 are composed of 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 coated on the surface of the gas diffusion layer. Respectively. The electrode catalyst layers are joined to both surfaces of the solid polymer electrolyte membrane 36.
[0025]
A fuel gas flow path 42 that connects the fuel gas supply passage 32a and the fuel gas discharge passage 32b is formed on a surface 26a of the first separator 26 facing the electrolyte membrane / electrode structure 24. The fuel gas passage 42 is provided with a plurality of grooves extending in the direction of arrow B, for example. On the surface 26b of the first separator 26, a cooling medium flow path 44 that connects the cooling medium supply communication hole 34a and the cooling medium discharge communication hole 34b is formed. The cooling medium flow path 44 has a plurality of grooves extending in the direction of arrow B.
[0026]
The surface 28a of the second separator 28 facing the electrolyte membrane / electrode structure 24 is provided with, for example, an oxidizing gas flow path 46 including a plurality of grooves extending in the direction of arrow B. Reference numeral 46 communicates with the oxidizing gas supply communication hole 30a and the oxidizing gas discharge communication hole 30b.
[0027]
A hole 48 into which a fastening bolt described later is inserted is formed in the unit cell 12. For example, three holes 48 are provided at each of the upper and lower sides. A seal member (not shown) is interposed between the electrolyte membrane / electrode structure 24 and the first and second separators 26 and 28.
[0028]
As shown in FIG. 1, an oxidizing gas supply port 50a communicating with the oxidizing gas supply communication hole 30a and the fuel gas discharge communication hole 32b is provided at one edge of the end plate 20a in the long side direction (arrow B direction). And a fuel gas outlet 52b. A fuel gas supply port 52a and an oxidant gas discharge port 50b are provided at the other end of the end plate 20a in the long side direction to communicate with the fuel gas supply communication hole 32a and the oxidant gas discharge communication hole 30b, respectively.
[0029]
A cooling medium supply port 54a communicating with the cooling medium supply communication hole 34a is provided at one end of the end plate 20a in the short side direction, and a cooling medium supply port 54a is provided at the other end of the end plate 20a in the short side direction. A cooling medium discharge port 54b communicating with the medium discharge communication hole 34b is provided.
[0030]
The intermediate plate 22 is formed of a metal plate (for example, stainless steel) similarly to the first and second separators 26 and 28. One or two or more intermediate plates 22 are provided so as to partition a predetermined number of unit cells 12 in the stacked body 14. The number of the unit cells 12 depends on the use condition, the dimensions of various constituent members, and the like. It is set according to the material and the like.
[0031]
As shown in FIGS. 1 and 4, the intermediate plate 22 is supported and fixed in parallel to the end plates 20a and 20b via a parallel support mechanism 60. The parallel support mechanism 60 fastens between the end plates 20 a and 20 b and penetrates the intermediate plate 22, for example, with six fastening bolts 62, and is externally mounted on the fastening bolts 62, and sandwiches both surfaces of the intermediate plate 22. And insulating collar members 64a and 64b.
[0032]
The fastening bolt 62 has an insulating layer (or insulating film) provided on the outer peripheral surface. The fastening bolt 62 is inserted into the laminated body 14 from the end plate 20a, and a nut 66 is screwed into an end protruding from the end plate 20b ( (See FIG. 4). The inner peripheral surface of the hole 48 provided in the laminate 14 is provided with a gap of, for example, 0.05 mm on one side between the inner peripheral surface of the insulating collar members 64a and 64b, so that the inner peripheral surface of the laminated member 14 is protected from running vibration and the like. This prevents the unit cell 12 from being shifted.
[0033]
The intermediate plate 22 is formed with a hole 68 into which the fastening bolt 62 is inserted. At both ends of the hole 68, a large-diameter hole into which the ends of the insulating collar members 64a and 64b are inserted to a predetermined depth. The holes 70a and 70b communicate with each other. An insulating collar member 64a is interposed between the end plate 20a and the intermediate plate 22, while an insulating collar member 64b is interposed between the intermediate plate 22 and the end plate 20b.
[0034]
The operation of assembling the fuel cell stack 10 configured as described above will be described below.
[0035]
First, a plurality of unit cells 12 are stacked in the direction of arrow A, and a predetermined number of, for example, one intermediate plate 22 is interposed at an intermediate position to obtain a stacked body 14. Terminal terminals 16a, 16b and insulator plates 18a, 18b are disposed at both ends of the laminate 14 in the laminating direction.
[0036]
Therefore, the insulating collar member 64a is inserted into the hole 48 of the laminate 14 from one side in the stacking direction, and the tip of the insulating collar member 64a fits into the hole 70a of the intermediate plate 22. The insulating collar member 64b is inserted into the hole 48 from the other side in the stacking direction, and the tip of the insulating collar member 64b fits into the hole 70b of the intermediate plate 22. In this state, the end plates 20a, 20b are arranged at both ends of the laminate 14, that is, outside the insulator plates 18a, 18b.
[0037]
Furthermore, the fastening bolt 62 is inserted from the end plate 20a into the end plate 20b through the inside of the laminated body 14. As shown in FIG. 4, the fastening bolt 62 is inserted into the insulating collar member 64b from the insulating collar member 64a through the hole 68 of the intermediate plate 22, and protrudes outward from the end plate 20b. A nut 66 is screwed into an end of the fastening bolt 62, and a predetermined fastening load is applied between the end plates 20a and 20b.
[0038]
In this case, in the first embodiment, the intermediate plate 22 interposed in the stacked body 14 is supported and fixed to the end plates 20a and 20b in parallel with each other via the parallel support mechanism 60. Therefore, since the inside of the stacked body 14 is divided into a predetermined number of unit cells 12 via the intermediate plate 22, there is a possibility that the shape errors of the unit cells 12 are accumulated and the stacked body 14 is inclined in the stacking direction. Absent.
[0039]
In particular, when the first and second separators 26, 28 constituting each unit cell 12 are made of a thin metal plate, it is extremely difficult to obtain the parallelism between the first and second separators 26, 28. At that time, in the first embodiment, since the intermediate plate 22 can surely maintain the parallelism with respect to the end plates 20a and 20b, the parallelism of each unit cell 12 can be effectively secured. Become.
[0040]
Thus, with a simple configuration, the contact resistance in the stacked body 14 can be reduced, the desired sealing properties can be secured, and the effect of easily improving the power generation performance can be obtained.
[0041]
Moreover, the intermediate plate 22 is fixed between the end plates 20a and 20b. For this reason, when the fuel cell stack 10 is used, for example, for in-vehicle use, the stacked body 14 does not move in the stacking direction when the vehicle suddenly starts or suddenly brakes. Therefore, a relatively large gap is not generated between the unit cells 12, a desired sealing property can be secured, and the power generation performance can be easily improved.
[0042]
The parallel support mechanism 60 includes a fastening bolt 62 that penetrates the intermediate plate 22 to fasten the end plates 20a and 20b, and an insulating collar member 64a that is externally mounted on the fastening bolt 62 and sandwiches both surfaces of the intermediate plate 22. , 64b. Thereby, the structure of the parallel support mechanism 60 can be simplified, and the position of the intermediate plate 22 is regulated by the insulating collar members 64a and 64b, and the tightening load acting on the laminate 14 is appropriately adjusted. It becomes possible.
[0043]
Next, the operation of the fuel cell stack 10 assembled as described above will be described.
[0044]
First, as shown in FIG. 1, a fuel gas such as a hydrogen-containing gas is supplied from a fuel gas supply port 52a of an end plate 20a into the fuel cell stack 10, and an oxygen-containing gas is supplied from an oxidant gas supply port 50a. Is supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied from the cooling medium supply port 54a. Therefore, in the stacked body 14, the fuel gas, the oxidizing gas, and the cooling medium are supplied in series in the direction of the arrow A1 to the plurality of unit cells 12 stacked in the direction of the arrow A.
[0045]
As shown in FIG. 3, the oxidizing gas is introduced from the oxidizing gas supply passage 30 a into the oxidizing gas passage 46 of the second separator 28, and flows along the cathode 40 of the electrolyte membrane / electrode structure 24. Moving. On the other hand, the fuel gas is introduced from the fuel gas supply passage 32 a into the fuel gas flow channel 42 of the first separator 26 and moves along the anode 38 of the electrolyte membrane / electrode structure 24.
[0046]
Therefore, in each of the electrolyte membrane / electrode structures 24, 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.
[0047]
Next, the fuel gas supplied to the anode 38 and consumed is discharged to the fuel gas discharge communication hole 32b, flows in the direction of the arrow A2, and then is discharged from the fuel gas discharge port 52b of the end plate 20a. Similarly, the oxidizing gas supplied to and consumed by the cathode-side electrode 40 flows in the arrow A2 direction along the oxidizing gas discharge communication hole 30b, and is then discharged from the oxidizing gas discharge port 50b of the end plate 20a. (See FIG. 1).
[0048]
The cooling medium supplied to the cooling medium supply port 54a is introduced into the cooling medium flow path 44 of the first separator 26 from the cooling medium supply communication hole 34a, and then flows along the arrow B direction. After cooling the electrolyte membrane / electrode structure 24, the cooling medium moves through the cooling medium discharge communication hole 34b in the direction of arrow A2, and is discharged from the cooling medium discharge port 54b of the end plate 20a.
[0049]
FIG. 5 is a schematic perspective view of a fuel cell stack 80 according to the second embodiment of the present invention. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0050]
In the fuel cell stack 80, the end plates 20a and 20b are integrally connected via a case member 82. The case member 82 includes a lower plate 84a, an upper plate 84b, and side plates 84c and 84d, which are fixed to the end plates 20a and 20b via bolts 85.
[0051]
An intermediate plate 86 is provided in the stacked body 14 at a predetermined position in the stacking direction, for example, at an intermediate position of the stacked body 14. The intermediate plate 86 is formed of a metal plate (for example, a SUS material), and is supported and fixed to the end plates 20a and 20b in parallel with each other via a parallel support mechanism 90.
[0052]
As shown in FIG. 6, the parallel support mechanism 90 is provided on each of four sides of the intermediate plate 86, and is provided with a plurality of projections 92a to 92d which are spaced apart by a predetermined interval and project outward, a lower plate 84a, and an upper plate 84b. And a plurality of openings 94a to 94d formed in the side plates 84c and 84d and fitted with the protrusions 92a to 92d, respectively. The openings 94a to 94d are set at positions separated from the end plates 20a and 20b by a predetermined distance.
[0053]
The operation of assembling the fuel cell stack 80 configured as described above will be described below.
[0054]
First, the projection 92a of the intermediate plate 86 fits into the opening 94a of the lower plate 84a, and the intermediate plate 86 is held by the lower plate 84a. On both sides of the intermediate plate 86, a predetermined number of unit cells 12 are stacked in the direction of arrow A to obtain a stacked body 14. Terminal terminal plates 16a and 16b, insulator plates 18a and 18b, and end plates 20a and 20b are provided at both ends in the stacking direction of the stacked body 14.
[0055]
Next, the upper plate 84b and the side plates 84c and 84d are arranged so as to cover the stacked body 14. At this time, the projections 92b of the intermediate plate 86 fit into the openings 94b of the upper plate 84b, and the projections 92c, 92d of the intermediate plate 86 fit into the openings 94c, 94d of the side plates 84c, 84d. Fit. In this state, the lower plate 84a, the upper plate 84b, and the side plates 84c, 84d are fixed to the end plates 20a, 20b via bolts 85.
[0056]
In this case, in the second embodiment, the intermediate plate 86 is connected to the case member 82 via the parallel support mechanism 90 having the projections 92a to 92d and the openings 94a to 94d, that is, to the end plates 20a and 20b. Are supported and fixed in parallel with each other. Therefore, the same effects as in the first embodiment can be achieved, such as maintaining the surface pressure in the laminate 14 uniformly, reducing the contact resistance with a simple configuration, and securing a desired sealing property. Is obtained.
[0057]
【The invention's effect】
Since the fuel cell stack according to the present invention is divided into a predetermined number of unit cells via the intermediate plate in the stack, a shape error of each unit cell may be accumulated and the stack may be inclined in the stacking direction. Absent. Therefore, the surface pressure in the laminate can be maintained uniform, and the contact resistance in the laminate can be reduced with a simple configuration.
[0058]
In addition, since the intermediate plate is fixed between the end plates, for example, when the intermediate body is used in a vehicle, the laminated body does not move in the laminating direction when the vehicle suddenly starts or suddenly brakes. Accordingly, a relatively large gap is not generated between the unit cells, a desired sealing property can be secured, and the power generation performance can be easily improved.
[Brief description of the drawings]
FIG. 1 is a schematic overall perspective view of a fuel cell stack according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional side view of the fuel cell stack.
FIG. 3 is an exploded perspective view of a unit cell constituting the fuel cell stack.
FIG. 4 is an explanatory cross-sectional view of an intermediate plate and a parallel support mechanism constituting the fuel cell stack.
FIG. 5 is a schematic perspective view of a fuel cell stack according to a second embodiment of the present invention.
FIG. 6 is an exploded perspective view of a case member and a parallel support mechanism constituting the fuel cell stack.
FIG. 7 is an internal schematic explanatory view of the fuel cell of Patent Document 1.
[Explanation of symbols]
10, 80 ... fuel cell stack 12 ... unit cell 14 ... laminate 20a, 20b ... end plate 22, 86 ... intermediate plate 24 ... electrolyte membrane / electrode structure 26, 28 ... separator 36 ... solid polymer electrolyte membrane 38 ... anode Side electrode 40 Cathode side electrode 48, 68, 70a, 70b Hole 60, 90 Parallel support mechanism 62 Fastening bolt 64a, 64b Insulating collar member 66 Nut 82 Case member 84a Lower plate 84b Upper Plates 84c, 84d: Side plates 92a to 92d: Projections 94a to 94d: Openings

Claims (2)

An electrolyte / electrode structure provided with electrodes on both sides of the electrolyte is provided with a unit cell sandwiched by separators, and a plurality of the unit cells are stacked to form a laminate, and end plates are provided at both ends in the stacking direction of the laminate. Is a fuel cell stack, wherein
In the laminate, an intermediate plate disposed corresponding to a predetermined position in the lamination direction,
A parallel support mechanism for supporting and fixing the intermediate plate in parallel with the end plate,
A fuel cell stack comprising: 2. The fuel cell stack according to claim 1, wherein the parallel support mechanism penetrates the intermediate plate and fastens the end plates with each other;
A collar member which is provided on the fastening bolt and sandwiches both surfaces of the intermediate plate,
A fuel cell stack comprising:

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