JP2000251902A - Gas separator for fuel cell, method of manufacturing the same, and fuel cell - Google Patents

Abstract

(57) Abstract: To suppress warpage of a gas separator for a fuel cell. A separator (30) includes a current collector (16) and an outer edge (17). Two concave portions 50 and 51 are formed. The concave portions 50 and 51 are provided with a plurality of convex portions 55. Separator 30
When the fuel cell is assembled by using the concave portions 50 and 5
1 and the convex portions 55 provided therein form a gas flow path between adjacent members. The current collector 16 has a substantially square shape, and portions corresponding to the four corners are formed in a smooth curved shape having no corner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas separator for a fuel cell, a method of manufacturing the same, and a fuel cell. More specifically, the present invention relates to a fuel cell comprising a plurality of single cells stacked and provided between adjacent single cells. While forming a fuel gas flow path and an oxidizing gas flow path between adjacent members,
The present invention relates to a fuel cell gas separator for separating a fuel gas and an oxidizing gas, a method for manufacturing the same, and a fuel cell.

[0002]

2. Description of the Related Art A gas separator for a fuel cell is a member constituting a fuel cell stack in which a plurality of single cells are stacked, and is provided with sufficient gas impermeability to supply each of the adjacent single cells. The fuel gas and the oxidizing gas are prevented from being mixed. Conventionally, such a fuel cell gas separator has been manufactured using a carbon material or a metal material having sufficient conductivity. In general, since a metal material has excellent strength, it is possible to produce a thinner gas separator than when a carbon material is used, and by making the gas separator thin, it is possible to reduce the size of the entire fuel cell. It becomes possible.

[0003] A gas separator for a fuel cell usually has a concavo-convex structure having a predetermined shape on its surface, and the concavo-convex structure allows the above-described fuel gas and oxidizing gas to be exchanged between adjacent members in the fuel cell. Form a gas flow path. As a method of manufacturing a gas separator having such a concavo-convex structure using a metal material, a method of press-forming a metal plate has been proposed (for example, Japanese Patent Application Laid-Open No. H10-241709).
No.). According to such a manufacturing method, since a gas separator for a fuel cell can be manufactured by a simple method called press molding, the manufacturing process is simplified and shortened to improve productivity and suppress an increase in manufacturing cost. be able to.

[0004]

However, in the case of manufacturing a gas separator having a concavo-convex structure of a predetermined shape by press-forming a metal plate, the metal plate is formed in a region where the concavo-convex structure is formed. Since "bending" and "stretching" are performed, stress due to press molding occurs inside the metal plate, and there is a problem that the resulting gas separator is warped. If the gas separator is warped, there is a problem that the operation of assembling the fuel cell by stacking such gas separators becomes extremely difficult. Furthermore, when the fuel cell is assembled by forcibly stacking the warped gas separators, the durability of the fuel cell may be impaired due to the occurrence of stress in each gas separator. Therefore, a gas separator with less warpage has been desired.However, a method for sufficiently suppressing the warpage of the gas separator without impairing the advantages of manufacturing a gas separator by press-molding a metal plate is conventionally known. Did not.

The gas separator for a fuel cell, the method of manufacturing the same, and the fuel cell according to the present invention solve these problems and sufficiently suppress the warpage of the gas separator for a fuel cell.
The purpose of the invention is to prevent the adverse effects caused by the warpage of the gas separator, and the following structure is adopted.

[0006]

The first gas separator for a fuel cell according to the present invention is used for a fuel cell in which a plurality of single cells are stacked to obtain an electromotive force by an electrochemical reaction. A fuel cell gas separator constituting the single cell together with a member forming an electrolyte layer and an electrode, comprising a current collecting region provided with a plurality of uneven structures on a surface thereof, wherein the current collecting region includes the fuel cell. When the gas separator is incorporated into the fuel cell, the uneven structure forms a gas flow path for the electrochemical reaction between adjacent members, and the uneven structure is formed in the current collecting region. It is necessary that the outer peripheral line of the current collecting region is formed in a smooth line shape having no corners so that the distribution of the stress generated in the current collecting region is not biased by providing To.

A second gas separator for a fuel cell according to the present invention is used for a fuel cell in which a plurality of single cells are stacked to obtain an electromotive force by an electrochemical reaction, together with a member forming an electrolyte layer and an electrode. A fuel cell gas separator constituting the single cell, the surface of which includes a current collecting region provided with a plurality of uneven structures on the surface thereof, wherein the current collecting region incorporates the fuel cell gas separator into the fuel cell. In such a case, the concavo-convex structure forms a gas flow path for the electrochemical reaction between adjacent members, and the current collecting region has a substantially polygonal shape,
At least one of the substantially polygonal corners of the current collecting region is replaced with the corner so as to suppress the distribution of stress generated by providing the uneven structure in the current collecting region. Therefore, the gist of the present invention is that it is formed in a smooth curved shape.

[0008] According to the first gas separator for a fuel cell of the present invention configured as described above, the current collecting region having the concavo-convex structure forming the gas flow path in the fuel cell is provided with the concavo-convex structure. The outer peripheral line of the current collecting region is formed in a smooth line shape having no corners so that the distribution of the stress generated in the current collecting region is not biased. Further, according to the second gas separator for a fuel cell of the present invention, the current collector including the uneven structure forming the gas flow path in the fuel cell has a substantially polygonal shape. At least one of the substantially polygonal corners is formed in a smooth curved shape in place of the corners so as to suppress the distribution of stress generated by providing the uneven structure to the corners. . As described above, since the distribution of stress in the current collecting region is prevented from being biased, the first and second fuel cell gas separators of the present invention have an effect that warpage is sufficiently suppressed. Moreover, according to the first and second fuel cell gas separators of the present invention, the warpage of the fuel cell gas separator is sufficiently suppressed, so that the assembly when assembling the fuel cell using the separator 30 is facilitated. It will be easier.

In the second gas separator for a fuel cell according to the present invention, the substantially polygonal shape may be a substantially square shape.

In the first and second gas separators for a fuel cell according to the present invention, the current collecting region may be formed by a metal plate, and the uneven structure may be formed by press-forming the metal plate. Good.

The warpage of the gas separator caused by the uneven distribution of stress due to the formation of the concavo-convex structure is particularly problematic when a metal plate is press-formed to manufacture a separator. When forming a current collecting area by pressing a metal plate,
Since the bias of the distribution of stress can be suppressed by setting the shape of the current collecting region to the shape described above, the advantage of manufacturing a gas separator by pressing a metal plate (easy manufacturing and low cost) And a metal separator having a sufficiently small warpage can be obtained without impairment. Further, since it becomes possible to suppress the warpage of the metal gas separator, it is possible to manufacture a gas separator using a thinner metal plate, and by using such a thinner metal plate, the gas separator can be manufactured. The entire fuel cell provided can be further reduced in size.

Further, in such a fuel cell gas separator, the current collecting region in which the concavo-convex structure is formed by press-molding a metal plate is different from other regions constituting the fuel cell gas separator. The body may be formed.

With such a configuration, by forming the current collecting region into the above-described shape, the advantage of being able to press-mold a metal plate (simplicity and low cost) is utilized, and the metal current collecting region is formed. Warpage can be suppressed. Furthermore, by making the region other than the current collecting region separate from the current collecting region, the current collecting region in which warpage is suppressed can be combined with another member that does not warp, thereby further suppressing warping of the entire separator. be able to. Also, another member separate from the current collecting area,
When formed of a material having no conductivity, in a fuel cell assembled using this gas separator, a structure for insulation provided around the fuel cell can be simplified.

The method of manufacturing a gas separator for a fuel cell according to the present invention is used for a fuel cell in which a plurality of single cells are stacked to obtain an electromotive force by an electrochemical reaction, and the member for forming an electrolyte layer and an electrode is provided together with the unit. Manufacture of a gas separator for a fuel cell constituting a cell, the surface of which has a plurality of concave-convex structures capable of forming a flow path of a gas for the electrochemical reaction in the fuel cell. A method of: (a) preparing a base material of the fuel cell gas separator; and (b) applying a predetermined external force to the base material to form the plurality of irregularities on the surface of the base material. Forming a current collecting region having a structure, wherein the step (b) suppresses uneven distribution of stress generated in the current collecting region due to the external force when the current collecting region is formed. Before And summarized in that to form the shape of the peripheral line of the collector region in a smooth curve.

According to the method of manufacturing a gas separator for a fuel cell of the present invention having the above-described structure, the uneven distribution of the stress generated in the current collecting region can be suppressed, so that the fuel cell has a sufficiently small warpage. Gas separator can be manufactured. As described above, the warpage of the manufactured gas separator is sufficiently reduced, so that the ratio of the manufactured gas separator that is determined to be defective due to the warpage can be sufficiently suppressed, and the production of the gas separator can be reduced. Properties can be sufficiently ensured.

In the method of manufacturing a gas separator for a fuel cell according to the present invention, in the step (a), a metal plate is prepared as the base material, and in the step (b), the external force is applied to the metal plate. In addition, the current collecting region may be formed by press-forming the metal plate.

According to such a manufacturing method, it is possible to manufacture a metal gas separator for a fuel cell having a sufficiently small warpage without impairing the advantages of the press molding described above.

The fuel cell of the present invention receives gas supply,
A fuel cell that obtains an electromotive force by an electrochemical reaction,
The gist of the present invention is to provide a fuel cell gas separator according to any one of claims 1 to 5.

According to such a fuel cell, since the warpage of the gas separator used is sufficiently suppressed, the operation of assembling the fuel cell becomes easy, and the fuel cell uses a separator in which a large stress is generated. By assembling the fuel cell, there is no possibility that the durability of the fuel cell is impaired.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the configuration and operation of the present invention described above, embodiments of the present invention will be described below based on examples. The fuel cell according to the first embodiment of the present invention is a polymer electrolyte fuel cell and has a stack structure in which a plurality of single cells are stacked. FIGS. 1 and 2 are plan views showing the configuration of a separator 30 provided in the fuel cell of the first embodiment. FIG.
0 shows the state of one surface, and FIG. 2 shows the state of the other surface of the separator 30. First, FIGS. 1 and 2
Based on the above, the configuration of the separator 30 will be described.

The separator 30 is composed of an outer edge 17 forming an outer frame thereof and a current collector 16 disposed inside the outer edge 17, and has a square laminated surface as a whole when assembled into a fuel cell. It has a certain plate-like structure. The outer edge 17 is
It is formed of a resin having no conductivity. Also,
The current collector 16 is formed by press-molding a metal plate, and has an uneven structure of a predetermined shape on its surface. Current collector 16 formed by pressing a metal plate
On the other hand, the separator 30 in which the current collector 16 and the outer edge 17 are joined is manufactured by insert-molding a predetermined resin.

The separator 30 has ten holes near its periphery, that is, at the outer edge portion 17. In the vicinity of one side of the separator 30, holes 40 to 43, which are four holes adjacent to the side, are provided. In the vicinity of the side opposite to this side, the holes 44 to 47, which are also adjacent, are provided. Is provided. Further, the hole 44
A hole 48 is provided in the vicinity of one of the corners provided at the four corners of the separator 30, and a corner adjacent to the hole 47 and adjacent to the corner described above. A hole 49 is provided in the vicinity of. When a fuel cell is configured using the separator 30, these holes form a manifold that serves as a fluid flow path, as described later. In FIGS. 1 and 2, the member numbers of the holes are used. In addition, the member numbers of the manifolds formed by the respective holes are also shown in parentheses.

On one surface of the separator 30 (FIG. 1)
2), that is, on one surface of the current collector 16, two concave portions 50 and 51 are provided. Each of these recesses is formed in a horizontal U-shape parallel to each other. As described above, since the current collecting portion 16 and the outer edge portion 17 are joined, the concave portion 50 formed in the current collecting portion 16 has, at both ends thereof, the holes 44 provided in the outer edge portion 17 and The holes 45 are in communication with each other.
The recess 51 communicates with the hole 46 and the hole 47 at both ends. Similarly, on the other surface of the separator 30 (on the surface shown in FIG. 2), that is, on the other surface of the current collector 16, two recesses 52, 5 are provided.
3 are formed in a parallel U-shape (U-shape opposite to the concave portions 50 and 51). The recess 52 communicates with the hole 40 and the hole 41 at both ends thereof, and the recess 53 communicates with the hole 42 and the hole 43 at both ends thereof. These recesses 50 to 53 form a predetermined space between the separator 30 and a member (a gas diffusion electrode described later) adjacent to the separator 30 when a fuel cell is formed using the separator 30, and provide a gas to be used for an electrochemical reaction. Is formed.

As will be described later, a fuel cell formed by using the separator 30 is formed by sequentially laminating a plurality of members including the separator 30, and the recess formed on the surface of the current collector 16 is As described above, the flow path of the gas used for the electrochemical reaction is formed between the inside and the member adjacent to the separator 30. Therefore, in the stacking surface of the separator 30 in the fuel cell, a region where two concave portions are formed on each surface of the separator 30, that is, a region including the current collector 16, is where the electrochemical reaction proceeds in the fuel cell. Corresponding to the region of interest.

In the separator 30 of this embodiment, the region formed by the current collector 16 is formed in a substantially square shape.
The sides forming the portions corresponding to the four corners are characterized by a smooth curve that does not form a corner.
Referring to FIG. 1, in the concave portion 50, a portion in contact with the hole 44 provided near the corner of the separator 30 and a hole 40 provided near the corner of the separator 30.
The side forming the concave portion 50 and the outer periphery of the current collecting portion 16 have a smooth curve with the portion adjacent to the portion. Further, in the concave portion 51, a portion in contact with the hole 47 provided near the corner of the separator 30 and a portion adjacent to the hole 43 provided near the corner of the separator 30 include:
The sides forming the concave portion 51 and the outer periphery of the current collector 16 are smooth curves (see the area surrounded by the dotted circle in FIG. 1). The current collector 16 has concave portions 52 and 53 on the back surface thereof.
Similarly, on the surface side shown in FIG. 2, similarly, the sides forming the portions corresponding to the four corners of the current collecting unit 16 and the sides located at the corresponding locations in the concave portions 52 and 53 are: It has a smooth curve that does not form a corner.

Also, in the separator 30 shown in FIGS. 1 and 2, the concave portions 50 to 53 are represented as a concave structure having a flat bottom surface. A plurality of convex structures having a predetermined shape protruding from the bottom surface are provided. FIG. 3 shows an example of such a convex structure provided in the concave portions 50 to 53. FIG. 3A shows the hole 44.
FIG. 3B is a plan view illustrating a state in which a part of the recess 50 is enlarged, and FIG. 3B is a cross-sectional view illustrating a cross section taken along line AA in FIG. As shown in FIG.
0 has a plurality of convex portions 55 protruding from the bottom surface thereof. Each of the protrusions 55 has a substantially rectangular cross section, and is formed so that the heights thereof are substantially the same.

FIG. 3 shows a projection 55 provided in the recess 50.
Although only the concave portion 51 is shown, the concave portions 51 and the concave portions 52 and 53 formed on the other surface of the separator 30 are also provided with a plurality of convex portions projecting from the bottom surface. When a fuel cell is configured using the separator 30, these protrusions ensure sufficient conductivity by coming into contact with a member adjacent to the separator 30, and the above-described gas flow formed by the recesses 50 to 53 is formed. It functions to diffuse the gas passing through the passage and efficiently provide the gas passing through the gas passage to the electrochemical reaction. Therefore, the shape of the convex portion 55 may be different from the shape shown in FIG. 3, and it is possible to realize sufficient conductivity between adjacent members,
It is sufficient that the gas passing through the gas flow path formed by the concave portions 50 to 53 can be sufficiently diffused.

Next, the fuel cell of the present embodiment assembled using the separator 30 configured as described above will be described. The fuel cell of this embodiment is a polymer electrolyte fuel cell, and is formed as a stack structure in which a plurality of single cells are stacked. FIG. 4 is an exploded perspective view showing the configuration of a single cell 20 which is a basic unit of the stack structure 15 constituting the fuel cell of this embodiment, and FIG. 5 is a perspective view showing the appearance of the stack structure 15. The single cell 20 sandwiches the electrolyte membrane 31 between the cathode 32 and the anode 33 (not shown),
This sandwich structure is further separated from both sides by a separator 30.
It is constituted by sandwiching between. By stacking a predetermined number of such single cells 20, a stack structure 15 is formed. Hereinafter, based on FIGS. 4 and 5,
The unit cell 20 and the stack structure 15 will be described.

The electrolyte membrane 31 is a proton-conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and has good electric conductivity in a wet state. In this example, a Nafion membrane (manufactured by DuPont) was used. On the surface of the electrolyte membrane 31, platinum as a catalyst or an alloy composed of platinum and another metal is supported. The cathode 32 and the anode 33 are gas diffusion electrodes. These include carbon cloth woven with carbon fiber yarn, carbon paper, and carbon felt.
It is composed of a member having sufficient gas diffusivity and conductivity.

A separator 30 is laminated with an electrolyte membrane 31, a cathode 32 and an anode 33 to form a single cell 20.
When forming the stack structure 15, each concave portion provided on the separator 30 forms a gas flow path with an adjacent gas diffusion electrode. In other words, the recesses 52 and 53 that connect the holes 40 and 41 and the holes 42 and 43 form an oxidizing gas flow path in a single cell between the holes 40 and 41 and the surface of the adjacent cathode 32, and the holes 44 and 4.
5 and the recesses 50 and 51 connecting the holes 46 and 47 form a fuel gas flow path within a single cell with the surface of the adjacent anode 33.

When assembling the stack structure 15 by stacking the single cells 20, the holes 4 provided in each separator 30 are provided.
Oxygen gas supply manifolds 60 and 62 penetrate the stack structure 15 in the stacking direction thereof.
To form The holes 41 and 43 also form oxidizing gas discharge manifolds 61 and 63 that pass through the inside of the stack structure 15 in the stacking direction. Further, the hole 4
The fuel gas supply manifolds 64 and 66 respectively penetrate the stack structure in the stacking direction, and the holes 45 and 47 respectively define the fuel gas discharge manifold 6.
5, 67 are respectively formed (see FIG. 1). The gas flow in these gas channels formed in the stack structure 15 will be described later in detail (see FIGS. 6 and 7 described later). Further, in the stack structure 15, the holes 48 and 49 provided in each separator 30 form cooling water manifolds 68 and 69, respectively, which penetrate the inside of the stack structure 15 in the stacking direction (see FIG. 1). The cooling water manifold has a structure for circulating cooling water inside the fuel cell. Since heat is generated inside the fuel cell along with power generation, such a structure is provided to keep the inside of the fuel cell within a predetermined temperature range.

When assembling the stack structure 15 including the above-described members, the separator 30, the cathode 32, the electrolyte membrane 31, the anode 33, and the separator 30 are sequentially stacked in this order, and a predetermined number of the unit cells 20 are stacked. The return plate 70 is arranged at the end. Further, current collecting plates 36 and 37, insulating plates 38 and 39,
By arranging the end plates 80 and 88 sequentially, the stack structure 15 shown in FIG. 5 is completed.

The return plate 70 is formed of a gas-impermeable member having sufficient conductivity (for example, dense carbon). This return plate 7
0 is on the surface in contact with the structure in which the single cells 20 are stacked,
A plurality of concave portions having a predetermined shape are formed. The recess is provided at a position corresponding to the end of the gas manifold described above formed by the hole provided in the separator 30. By such a concave portion, the stack structure 15 is formed.
A predetermined gas discharge manifold and a gas supply manifold are communicated with each other at the end of the stack structure 15 so that a gas flow described later can be made inside the stack structure 15. Since the configuration of the return plate 70 does not directly relate to the main part of the present invention, further description on the structure of the return plate 70 will be omitted.

The current collecting plates 36 and 37 are formed of a gas-impermeable conductive material such as a dense carbon or copper plate, and the insulating plates 38 and 39 are formed of an insulating material such as rubber or resin. Is formed of a rigid metal such as steel. In addition, the current collector plates 36 and 37 are provided with output terminals 36A and 37A, respectively.
The electromotive force generated in the fuel cell constituted by the stack structure 15 can be output. The end plate 80, the insulating plate 38, the current collecting plate 36, and the return plate 70 are provided with six holes at the same corresponding positions. For example, in the end plate 80, holes 81 to
86 are provided (see FIG. 5).

The hole 81, the insulating plate 38 and the current collecting plate 3
The holes provided in the same position in the return plate 6 and the return plate 70 correspond to the fuel gas supply manifold 64 (formed by the holes 44 provided in each separator 30) when the stack structure 15 is configured.
To form a gas flow path communicating with the gas flow path. When the stack structure 15 is formed, the holes 82 and the holes provided at the same positions in the insulating plate 38, the current collecting plate 36, and the return plate 70 correspond to the fuel gas discharge manifold described above. A gas flow path communicating with 67 (formed by the hole 47 provided in each separator 30) is formed. Similarly, the hole 83, the insulating plate 38 and the current collector 3
6 and the return plate 70 have a correspondingly formed hole that forms a gas flow path that communicates with the oxidizing gas supply manifold 60 (formed by the hole 40 provided in each separator 30). And insulating plate 3
8, the current collecting plate 36, and the return plate 70, correspondingly provided holes form a gas flow path communicating with the oxidizing gas discharge manifold 63 (formed by the holes 43 provided in each separator 30). I do. The hole 8
5, and the corresponding holes provided at the same position in the insulating plate 38, the current collecting plate 36, and the return plate 70 are provided with the cooling water manifold 68 (each separator 30 (Formed by the hole 48 provided in the cooling water passage). Further, when the stack structure 15 is formed, the holes 86 and the holes provided in the insulating plate 38, the current collecting plate 36, and the return plate 70 at the same positions corresponding thereto are provided with the cooling water manifold 69. (Formed by the holes 49 provided in each separator 30).

When the fuel cell having the stack structure 15 is operated, the hole 81 provided in the end plate 80 is provided.
And a fuel gas supply device (not shown) are connected to supply a hydrogen-rich fuel gas into the fuel cell. Similarly, when operating the fuel cell, the hole 83 and an oxidizing gas supply device (not shown) are connected, and an oxidizing gas (air) containing oxygen is supplied into the fuel cell. Here, the fuel gas supply device and the oxidizing gas supply device are devices that humidify and pressurize a predetermined amount of each gas and supply the gas to the fuel cell. When operating the fuel cell, the hole 82 is connected to a fuel gas discharge device (not shown), and the hole 84 is connected to an oxidizing gas discharge device (not shown). As the fuel gas, a high-purity hydrogen gas other than the hydrogen-rich gas obtained by reforming the hydrocarbon may be used. Further, when the fuel cell is operated, the hole 85 is connected to a cooling water supply device (not shown), and the hole 86 is connected to a cooling water discharge device (not shown). Thus, the heat generated in the fuel cell is discharged to the outside of the fuel cell by the cooling water.

The order of lamination of the respective members when constituting the stack structure 15 is as described above. However, a predetermined sealing member is provided around the electrolyte membrane 31 in a region in contact with the separator 30. The sealing member serves to prevent the fuel gas and the oxidizing gas from leaking from the inside of each unit cell and to prevent the fuel gas and the oxidizing gas from being mixed in the stack structure 15.

The stack structure 15 composed of the members described above is held in a state where a predetermined pressing force is applied in the stacking direction, and the fuel cell is completed. The configuration for pressing the stack structure 15 is not shown because it does not relate to the main part of the present invention. In order to hold the stack structure 15 while pressing it, the stack structure 15 may be tightened using bolts and nuts, or a stack storage member having a predetermined shape may be prepared, and the stack storage member may be stacked inside the stack storage member. After storing the structure 15, both ends of the stack storage member may be bent to apply a pressing force to the stack structure 15.

Next, the flow of the fuel gas and the oxidizing gas in the fuel cell having the above configuration will be described. First, the fuel gas will be described. FIG. 6 is an explanatory diagram three-dimensionally illustrating the flow of the fuel gas in the stack structure 15, and FIG. 7 is an explanatory diagram similarly illustrating the flow of the fuel gas in a plan view. As described above, the fuel gas supply device provided outside the fuel cell is connected to the hole 81 provided in the end plate 80, and the fuel gas supplied from the fuel gas supply device is supplied to the insulating plate 38, The fuel gas is introduced into the fuel gas supply manifold 64 through holes provided at corresponding positions of the electric plate 36 and the return plate 70.
The fuel gas passing through the fuel gas supply manifold 64 is supplied to the gas flow path (the fuel gas flow path within the single cell) formed between the concave portion 50 of each separator 30 and the adjacent anode 33 in each single cell 20. ). The fuel gas guided to the fuel gas flow path in the single cell is subjected to an electrochemical reaction in each single cell, but the remaining fuel gas not involved in the reaction is supplied to a hole 45 provided in the separator 30. Is discharged to a fuel gas discharge manifold 65 formed by In FIG. 6, the flow of the fuel gas in the fuel gas flow path in the single cell formed by the concave portion 50 and the flow of the fuel gas in the fuel gas flow channel in the single cell formed by the concave portion 51 described later (U-shaped flow on the stacking surface) Is the stack structure 1
Although only three locations are shown in FIG. 5, in actuality, in all the single cells 20, the gas flows in the fuel gas flow path in the single cell formed inside. In the fuel gas discharge manifold 65, the fuel gas discharged from the fuel gas flow path in the single cell formed in each single cell merges while the fuel gas passes in the opposite direction to the fuel gas supply manifold 64.

Such a fuel gas is supplied to the stack structure 15.
When reaching the return plate 70 at the end, it is further guided into the fuel gas supply manifold 66 by the above-described concave portion provided on the surface of the return plate 70. The fuel gas introduced into the fuel gas supply manifold 66 is passed through the fuel gas supply manifold 66, and the anode 3 adjacent to the concave portion 51 of each separator 30.
The fuel gas is distributed to the fuel gas channels in the single cell formed between the fuel cells 3 and 3 and is passed through the fuel gas channel in the single cell to be subjected to an electrochemical reaction. The fuel gas that has passed through the fuel gas flow path in the single cell as described above is discharged to the fuel gas discharge manifold 67, merges with the fuel gas supply manifold 66 while flowing in the opposite direction, and reaches the return plate 70 again. The fuel gas that has reached the return plate 70 passes through a hole 82 provided in the end plate 80 and a hole provided in a corresponding position of the current collector 36, the insulating plate 38 and the return plate 70. It is discharged to a fuel gas discharge device connected to the section 82.

Although the flow of the fuel gas in the stack structure 15 has been described above, the flow of the oxidizing gas in the stack structure 15 is the same. That is,
The flow of the oxidizing gas is the same as that described with reference to FIGS. 6 and 7 except that the fuel gas supply manifolds 64 and 66 are respectively connected to the oxidizing gas supply manifolds 60 and 62, the fuel gas discharge manifolds 65 and 67 are connected to the oxidizing gas discharge manifold. In 61 and 63, the fuel gas flow path in the single cell formed by the recesses 50 and 51 may be replaced with the oxidizing gas flow path in the single cell formed by the recesses 52 and 53. The oxidizing gas supplied from the oxidizing gas supply device to the fuel cell first passes through the oxidizing gas supply manifold 60 while the separator 30
Is distributed to the oxidizing gas flow path in the single cell formed between the concave portion 52 and the cathode 32 provided for the oxidizing gas flow path and is subjected to an electrochemical reaction. The remaining oxidizing gas not involved in the reaction gathers in the oxidizing gas discharge manifold 61, flows in the opposite direction to the oxidizing gas supply manifold 60, and reaches the return plate 70.

The oxidizing gas is guided into the oxidizing gas supply manifold 62 by a predetermined recess provided in the return plate 70. Oxidizing gas supply manifold 6
The oxidizing gas introduced into 2 is distributed to an oxidizing gas flow path in a single cell formed between the concave portion 53 provided in each separator 30 and the cathode 32 and subjected to an electrochemical reaction. The oxidizing gas that has passed through the oxidizing gas flow path in the single cell as described above is discharged to the oxidizing gas discharge manifold 63, merges with the oxidizing gas supply manifold 62 while flowing in the opposite direction, and reaches the return plate 70 again. The oxidizing gas that has reached the return plate 70 passes through the holes 84 provided in the end plate 80 and the holes provided in the insulating plate 38, the current collector 36 and the return plate 70 at corresponding positions. It is discharged to an oxidizing gas discharge device connected to the section 84.

According to the embodiment described above, each of the separators 30 has a substantially rectangular current collector 1.
By forming the four corners of 6 so as to have a smooth curve with no corners, the warpage of the current collector 16 can be suppressed. Therefore, it is possible to solve the problem that the metal separator is warped without impairing the advantage of the simple and low-cost method of manufacturing the separator by press-molding the metal plate to manufacture the separator.

As described above, when a metal plate is press-formed to form a plurality of fine irregularities, the metal plate is warped due to the stress generated inside the metal plate due to bending or extension of the metal plate. It has been difficult to produce a metal separator with less warpage. However, as in the above embodiment, when the current collecting region having the uneven structure is formed so that the outer peripheral line thereof has a smooth linear shape having no corners, the distribution state of the uneven structure that causes stress is more improved. Become uniform. That is, as in the case of the outer shape of the separator 30, when the current collecting region has a rectangular shape having corners, the distance from the center of the current collecting region to each point on the outer peripheral line of the current collecting region is as follows.
Since the distance to these corners is the longest, on the diagonal line connecting the corners, more convex structures that generate stress will be provided than in other regions, and strong stress will act, but the above configuration This can suppress such bias of the stress distribution, and can effectively reduce the warpage of the separator 30.

As described above, the warpage of the separator 30 is suppressed, so that the assembly when assembling the fuel cell using the separator 30 is facilitated. In addition, since the warpage of the separator is sufficiently suppressed, it is possible to sufficiently suppress the proportion of the manufactured separators that are determined to be defective due to the warpage, and to sufficiently secure the productivity of the separator. it can. Further, by assembling the fuel cell using the separator in which a large stress is generated, there is no possibility that the durability of the fuel cell is impaired.

The warpage of the separator caused by the press forming of the metal plate becomes more remarkable as the metal plate subjected to the press forming for manufacturing the separator is thinner. Therefore, as in the above embodiment, by forming the current collecting portion so that the outer peripheral line has a smooth curved line with no corners, if the warpage of the separator is sufficiently suppressed, a thinner metal plate is used. Even when subjected to press forming,
It is possible to manufacture a separator with a sufficiently small warpage. In addition, since a thinner metal separator can be manufactured, the fuel cell can be further reduced in size.

Since the separator 30 has U-shaped recesses on its surface, the gas passing through the gas flow path in each single cell is bent at the gas flow path corresponding to the bottom of the U-shape. Passing through the section changes the flow direction in the opposite direction. Thus, by providing the bent portion and bending the gas flow path in the single cell halfway, the flow path cross-sectional area of the gas flow path in the single cell is reduced, and the flow rate and the flow velocity of the gas passing through the flow path are increased. By doing so, it is possible to improve the gas utilization rate, but at the bent portion, the pressure loss when the gas passes through the flow path increases. By making the shape of the bent portion a smooth curve as in the above-described embodiment, gas can be smoothly guided at the bent portion, and pressure loss when the gas passes through the bent portion can be suppressed. Further, in such a bent portion, when a corner is provided in the bent portion (when the corner is provided as the four corners of the substantially rectangular current collecting region), the flow of gas is not allowed in the corner. The region is likely to be sufficient and the progress of the electrochemical reaction is likely to be insufficient. Therefore, even if the four corners of the current collector are made into a smooth curve to reduce the area of the current collector corresponding to the corners as in the above embodiment, the battery performance is not significantly affected.

Further, according to the above embodiment, the current collector 16
By eliminating the corners at the four corners and forming a smooth curve, the manifold can be efficiently arranged in the fuel cell. That is, in the separator 30, the holes 40 to 43 forming the oxidizing gas manifold are provided along one side of the current collector 16 and the separator 30, and the fuel gas manifold is formed along the side opposed to these sides. Holes 44 to 47 are provided. here,
Since the four corners of the current collector 16 are formed in a smooth curved shape without corners, the four corners of the holes 40, 43, 44, 47 adjacent to the four corners of the current collector 16 and the four corners of the separator 30. There is a predetermined space between. Therefore, holes (holes 48, 49) for forming a cooling water manifold can be provided in this space, and there is no need to increase the lateral width of the separator to provide the cooling water manifold. By arranging the manifolds efficiently, it is possible to sufficiently increase the area ratio of the current collecting portion on the stack surface of the fuel cell.

The metal forming the current collecting portion 16 of the separator 30 may have sufficient conductivity, strength, and corrosion resistance, and may be, for example, stainless steel. Further, in order to further improve the corrosion resistance of the separator 30, a configuration in which a conductive layer having particularly excellent corrosion resistance, for example, a metal such as titanium or nickel, or a coating layer made of carbon is preferably provided on the surface of the current collector 16. .

Further, in the separator 30 of the above embodiment,
Although the current collecting portion 16 and the outer edge portion 17 are made of different members, they may be formed integrally. That is, a metal plate is press-formed to form a current collecting portion, and a hole is formed by punching a predetermined position of the metal plate, and the current collecting portion and the outer edge portion are integrated from one metal plate. Alternatively, a metal separator may be manufactured. Even in such a case, the shape of the outer edge of the current collector formed by press molding is
By forming a smooth curved shape without corners at the four corners, the unevenness of the current collector is formed, thereby suppressing the bias of the distribution of stress generated in the separator and obtaining an effect of reducing the warpage of the separator. Can be. In the separator 30 of the above-described embodiment, the current collector 16 is formed into the shape described above to suppress the warpage of the metal current collector 16 and to make the current collector 16 a resin that does not warp. By integrating the outer edge 17 with the outer edge 17, the warpage of the entire separator 30 can be further suppressed.

In the separator 30 of the above embodiment,
The current collector 16 is formed of two parallel U-shaped recesses on each surface, but the shape of the recess formed in the current collector may be any other shape.
That is, if the outer periphery of the current collector is formed so as to have a smooth curved shape without corners, even if the shape of the concave portion formed in the current collector is another shape, the inside of the current collector is formed by press molding. Of the separator can be suppressed, and the warpage of the separator can be reduced. Separator 3
FIG. 8 shows an example of a separator provided with a concave portion having a shape different from that of the concave portion provided in 0.

The separator 130 shown in FIG. 8 is formed by press-molding a metal plate, has a recess 150 on one surface thereof, and has holes 140, 143, 144 and 144 near each of the four corners. 147 is formed, and the hole 1 is located near the holes 143 and 144.
49, 148 are provided. Here, the recess 150
Is formed in a substantially circular shape, in which a plurality of convex structures are formed similarly to the convex portion 55 shown in FIG. 3 and communicate with the holes 144 and 147. Also, the separator 13
0 is provided with a recess similar to the recess 150 on the other surface (not shown).
Is in communication with When a fuel cell is configured using such a separator 130, the recess 150 forms a fuel gas flow path within a single cell, the holes 144 and 147 form a fuel gas manifold, and the holes 140 and 143 form oxidizing gas. The manifold and the holes 148 and 149 form a cooling water manifold. Further, in the fuel cell constituted by using the separator 130, in the fuel gas flow path in the single cell formed by the recess 150, the gas manifold formed by one of the holes 144 and 147 changes from the gas manifold formed by the other. Gas flows toward it.

In such a separator 130, the recess 1
The region where 50 is formed corresponds to the current collector described above,
By making the current collecting portion substantially circular, that is, by forming the outer periphery of the current collecting portion into a smooth curved shape having no corners, an effect of suppressing the warpage of the separator 130 can be obtained as in the above-described embodiment. Further, by forming the concave portion 150 in the above-described shape and providing a hole for forming the gas manifold along the concave portion 150, predetermined spaces are generated near the four corners of the separator 130. Therefore, the holes 148, 149 forming the cooling water manifold are provided here.
Can be provided, and similarly to the above-described embodiment, the effect that the manifold can be efficiently arranged can be obtained.

In the above-described embodiment, all four corners of the current collector are formed in a curved shape having no corners. However, at least one of the four corners may have such a configuration. . Even in such a case, by forming at least one of the four corners into a curved shape having no corner portion, a predetermined effect of suppressing the bias of the distribution of stress generated when the uneven shape is formed by press molding is obtained. Obtainable. Further, even if the shape of the current collecting portion is a polygonal shape other than a substantially quadrangular shape, the same effect as suppressing the warpage of the separator can be obtained by making the shape corresponding to the corner portion a smooth curve.

In the above-described embodiment, the current collector 16 having a predetermined uneven shape is formed on both surfaces by press-molding a single metal plate. However, two press-formed metal plates are bonded to each other. It is also possible to form a current collector. In other words, if it is difficult to form a current collector having a desired uneven shape on both surfaces only by plastic working such as press molding, a convex structure corresponding to any one surface of the current collector is formed. A metal plate is processed in such a manner that, together with a metal plate processed so as to form a convex structure corresponding to the other surface of the current collecting portion, the two are pasted together in a direction in which the convex structures do not face each other to form one current collecting portion. May be formed. In such a case as well, the effect of suppressing the warpage of the separator can be obtained by forming the outer periphery of the current collecting region into a smooth linear shape having no corners.

As described above, when a metal thin plate is press-formed, warpage of the formed body due to uneven stress distribution is a particularly serious problem, and the effect of forming the current collecting region into the above-described shape is particularly significant. Although it is remarkably obtained, even in the case where the uneven structure of the separator is formed by another method, the shape of the outer periphery of the current collecting region is made to have a smooth curve without corners, thereby suppressing the separator from warping. The effect of can be obtained. For example, by forming a metal that is melted by heat on a flat metal plate, even when forming an uneven structure on the separator surface, the shape of the outer periphery of the current collecting region is made to be a smooth curved shape without corners. Thereby, the warpage of the separator can be suppressed. In the embodiment described above, the stress distributed in the separator is generated by an external force that bends or stretches the metal plate, but when the molten metal is provided, the stress distributed in the separator is generated by an external force of heat. In addition, even if other materials and other manufacturing methods are used, such as when a separator is manufactured by press-molding a carbon material, by setting the shape of the current collecting region to the shape described above, the flow in the single cell can be improved. By providing the uneven structure for forming the path, the distribution of the stress generated in the separator can be suppressed from being biased, and the effect of further reducing the warpage of the separator can be obtained.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

[Brief description of the drawings]

FIG. 1 shows a separator 30 according to a preferred embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a state viewed from one surface.

FIG. 2 is an explanatory diagram illustrating a state where a separator 30 is viewed from the other surface.

FIG. 3 is an explanatory diagram showing a state of a convex portion 55 provided in a concave portion 50.

FIG. 4 is an exploded perspective view illustrating a configuration of a single cell 20.

FIG. 5 is a perspective view illustrating an appearance of a stack structure 15.

FIG. 6 is an explanatory diagram three-dimensionally illustrating a flow of a fuel gas in a stack structure 15;

FIG. 7 is an explanatory diagram illustrating a flow of a fuel gas in a stack structure 15 in a plan view.

FIG. 8 is an explanatory diagram illustrating a configuration of a separator 130.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 15 ... Stack structure 16 ... Current collecting part 17 ... Outer edge part 20 ... Single cell 30 ... Separator 31 ... Electrolyte membrane 32 ... Cathode 33 ... Anode 36, 37 ... Current collecting plate 36A, 37A ... Output terminal 38, 39 ... Insulating plate 40 ... 43 ... hole 44-47 ... hole 48, 49 ... hole 50-53 ... concave 55 ... convex 60, 62 ... oxidizing gas supply manifold 61, 63 ... oxidizing gas discharge manifold 64, 66 ... fuel gas supply manifold 65, 67 ... fuel gas discharge manifold 68, 69 ... cooling water manifold 70 ... return plate 80, 88 ... end plate 81-86 ... hole 130 ... separator 140, 143, 144, 147, 148, 149 ... hole 150 ... Recess

Claims (8)

[Claims] 1. A gas separator for a fuel cell, comprising a plurality of single cells stacked and used in a fuel cell for obtaining an electromotive force by an electrochemical reaction, wherein said gas separator comprises said single cell together with a member forming an electrolyte layer and an electrode. The surface of the fuel cell further includes a current collecting region provided with a plurality of uneven structures, and the current collecting region is configured such that when the fuel cell gas separator is incorporated in the fuel cell, the current collecting region is formed between adjacent members by the uneven structure. In between, while forming a gas flow path to be provided for the electrochemical reaction, so as to suppress the distribution of the stress generated in the current collecting area by providing the uneven structure in the current collecting area, A gas separator for a fuel cell, wherein an outer peripheral line of the current collecting region is formed in a smooth linear shape having no corners. 2. A gas separator for a fuel cell, which is used in a fuel cell in which a plurality of single cells are stacked to obtain an electromotive force by an electrochemical reaction, and constitutes the single cell together with a member forming an electrolyte layer and an electrode. The surface of the fuel cell further includes a current collecting region provided with a plurality of uneven structures, and the current collecting region is configured such that when the fuel cell gas separator is incorporated in the fuel cell, the current collecting region is formed between adjacent members by the uneven structure. A gas flow path for providing the electrochemical reaction is formed therebetween, and the shape of the current collecting region is substantially polygonal, and at least one of the substantially polygonal corners of the current collecting region is formed. The two corner portions are formed in a smooth curved shape instead of the corner portions so as to suppress the distribution of stress generated by providing the uneven structure in the current collection region. Gas separator charge the battery. 3. The gas separator for a fuel cell according to claim 2, wherein the substantially polygonal shape is a substantially square shape. 4. The fuel cell gas separator according to claim 1, wherein the current collecting region is formed by a metal plate, and the uneven structure is formed by press-forming the metal plate. Gas separator. 5. The fuel cell according to claim 4, wherein the current collecting region in which the concavo-convex structure is formed by press-molding a metal plate is formed separately from other regions constituting the fuel cell gas separator. Gas separator for fuel cells. 6. A gas separator for a fuel cell, which is used in a fuel cell in which a plurality of single cells are stacked to obtain an electromotive force by an electrochemical reaction, and constitutes the single cell together with a member forming an electrolyte layer and an electrode. A method of manufacturing a gas separator for a fuel cell having a plurality of concave and convex structures on its surface, in which a flow path of a gas to be subjected to the electrochemical reaction can be formed in the fuel cell; (B) applying a predetermined external force to the base material to form a current collecting region having the plurality of uneven structures on the surface of the base material; Wherein the step (b) includes forming a shape of an outer peripheral line of the current collecting region so as to suppress uneven distribution of stress generated in the current collecting region due to the external force when forming the current collecting region. Into a smooth curved shape A method for producing a gas separator for a fuel cell, comprising: 7. The method for producing a gas separator for a fuel cell according to claim 6, wherein in the step (a), a metal plate is prepared as the base material, and in the step (b), the metal plate is prepared. Apply the external force to
A method for manufacturing a gas separator for a fuel cell, wherein the current collecting region is formed by press-forming the metal plate. 8. A fuel cell which receives a supply of gas and obtains an electromotive force by an electrochemical reaction, comprising the gas separator for a fuel cell according to any one of claims 1 to 5.