JP3646181B2 - Method for producing metal separator for fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal separator for a fuel cell used for partitioning a cell composed of an anode and a cathode sandwiching an electrolyte, and more particularly to a method of manufacturing a metal separator for a fuel cell in which distortion during the molding of the separator is corrected.
[0002]
[Prior art]
Fuel cells that have been developed in recent years and that directly convert chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen have high power generation efficiency, and use cogeneration systems to generate heat. Can be used. In addition, fuel cells are attracting attention as a clean energy supply method used for automobiles, home appliances, and the like because they emit less nitrogen oxides that cause environmental pollution and global warming.
[0003]
The development of the fuel cell is in the process of transition from the initial phosphoric acid type fuel cell to the molten carbonate type fuel cell and the solid electrolyte type fuel cell. As shown in FIGS. 1 to 3, the molten carbonate type fuel cell is used. In FIG. 12, a single cell 7 has a sandwich structure in which an electrolyte plate 4 in which a molten carbonate is infiltrated into a porous material as an electrolyte is sandwiched between both anode (fuel electrode) 5 and cathode (oxygen electrode) 6 electrodes. The power generation is performed by the potential difference generated between the anode 5 and the cathode 6. The fuel cell 12 has separators 1 disposed on both sides of each cell 7 and is stacked by being stacked in multiple layers to have a necessary power generation capacity.
[0004]
The separator 1 serving as a partition is formed with concave and convex shapes to be gas flow paths 2 on the front and back surfaces in the central portion excluding the peripheral portion, and an anode gas supply manifold 10 and a cathode gas supply in the flat peripheral portion 3. A manifold 11 is provided so that different gases are circulated on both the front and back surfaces of the separator 1.
[0005]
As shown in FIG. 3, the separator 1 is configured such that the tops of the vertically elongated gas flow paths 2 formed on both the front and back surfaces are in contact with the anode 5 or the cathode 6 to transmit electrons to each electrode, and at the same time, the front and back of the metal separator 1. An anode gas (fuel gas) is supplied to the anode 5 from one gas flow path 2A formed on both surfaces, and a cathode gas (oxygen gas) is supplied to the cathode 6 from the other gas flow path 2C. Power generation is performed by the potential difference generated between the two. In addition, 13 in FIG. 3 has shown the spacer.
[0006]
Seal plates 8 and 9 are provided around the anode 5 or the cathode 6, the end portions of the seal plates 8 and 9 are bent and overlapped with the peripheral portion 3 of the separator 1, and the overlapped portion is sealed. A gas flow path 2 having confidentiality is formed in the separator 1.
[0007]
Conventionally, a separator for a fuel cell has been formed using carbon graphite having excellent gas impermeability and conductivity.
[0008]
However, since carbon graphite has no extensibility in the material, it has been necessary to form a concave-convex shape as a gas flow path on a hard carbon-based material by mechanical processing such as cutting. In addition to the high cost of the material itself, carbon graphite has a high cost for mechanical processing such as cutting, is difficult to mass-produce, and for fuel cells for automobiles that require an output of 50 to 100 kW, per stack Since several hundred separators are used, the separator occupies about 40% of the manufacturing cost of the fuel cell, and the price is tens of thousands of yen per sheet, which has been a factor in increasing the cost of the fuel cell.
[0009]
Further, carbon graphite is a porous material, and is not sufficient in strength. When a plurality of cells are stacked and fastened, the separator is deformed and broken over time.
[0010]
Therefore, in recent years, instead of the conventional carbon graphite, by using a metal thin plate, while maintaining the required strength by increasing the strength, the weight is reduced to about half of the conventional, relatively Development of metal separators capable of forming gas flow paths by inexpensive press working has been made.
[0011]
Since the molten carbonate fuel cell is operated at a high temperature of 600 ° C. to 700 ° C. and uses highly corrosive carbonate as an electrolyte, the separator material may be corroded by water vapor, flowing-out electrolyte, or the like. In addition, a metal separator is formed using a clad material in which nickel is clad on the surface of a metal plate such as stainless steel, aluminum, titanium, etc. to solve the durability problem due to corrosion.
[0012]
[Problems to be solved by the invention]
However, as shown in FIG. 7, the conventional metal separator 1 is formed with an uneven gas flow path 2 in the center portion of the metal plate because of the necessity of forming a gas supply manifold. A frame-shaped peripheral portion 3 is formed around the periphery. The center part of the metal separator 1 in which the gas flow path 2 is formed is rolled by pressing in the rolling direction (the arrow Y direction in FIG. 7), while the unpressed peripheral part 3 is not rolled and is not rolled. Keeps the state. For this reason, the extension of the center portion rolled for forming the gas flow path 2 is regulated by the peripheral portion 3 a orthogonal to the longitudinal direction of the gas flow path 2, and the metal separator 1 passes through the gas flow path 2. Centering on the formed center portion, a distortion that curves in a concave shape or a convex shape is generated (see FIGS. 7B and 7C). This distortion is an unavoidable phenomenon caused by pressing the center portion of the metal plate and rolling it into an uneven shape.
[0013]
As described above, when cells are stacked using a distorted metal separator, the contact pressure between the metal separator and the adjacent member is not uniform throughout the fuel cell, and the conductivity decreases in a region where the contact pressure is low. However, since the internal resistance during the operation of the fuel cell is increased, there is a problem that the power generation performance is lowered. Further, in the region where the surface pressure is low, the thermal conductivity is also lowered, so that the internal temperature of the fuel cell is also made uneven, leading to a decrease in power generation performance. Further, when a fuel cell is configured by stacking distorted metal separators, there is a problem that it is difficult to ensure gas sealing performance in the peripheral portion where the cells and metal separators are stacked.
[0014]
Therefore, the present invention was created in view of the various circumstances described above, and was produced by rolling a metal plate by a simple second step after press forming an uneven gas channel on a metal thin plate. An object of the present invention is to provide a method of manufacturing a metal separator for a fuel cell that can correct the distortion, thereby improving the power generation performance of the fuel cell.
[0015]
[Means for Solving the Problems]
In order to solve the above technical problem,
According to a first aspect of the present invention, there is provided a method for producing a metal separator for a fuel cell in which a vertically elongated uneven gas flow path for supplying anode gas or cathode gas to anode and cathode electrodes sandwiching an electrolyte is formed. The peripheral part remains on the left and right and up and down of the metal plate, the first step of press-forming a vertically elongated gas channel in the center part, and the peripheral part parallel to the longitudinal direction of the gas channel are fixed, and the gas And a second step of applying a tensile force in a direction orthogonal to the longitudinal direction of the gas flow channel only to a peripheral portion orthogonal to the longitudinal direction of the flow channel .
[0016]
In the first aspect of the present invention, after the first step of press-molding the gas flow path, the peripheral portion perpendicular to the longitudinal direction of the gas flow path is stretched in a direction perpendicular to the longitudinal direction of the gas flow path. The distortion of the metal separator caused by the extension of the center portion rolled by the formation of the gas flow path being restricted at the non-rolled peripheral portion orthogonal to the longitudinal direction of the gas flow path is corrected.
[0017]
In the second step, the peripheral part parallel to the longitudinal direction of the gas flow path is fixed, and a tensile force is applied only to the peripheral part orthogonal to the longitudinal direction of the gas flow path. The tensile force does not affect the path, and the flatness of the metal separator as a whole can be improved while maintaining a normal gas flow path configuration, and a metal separator without distortion can be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, as shown in FIG. 4, the left and right and upper and lower peripheral portions 3 of the metal plate 1 ′ remain, and the first and second uneven gas flow paths 2 are press-formed on both the front and back surfaces of the center portion of the metal plate 1 ′. Perform the process.
[0019]
Next, as shown in FIG. 5, the left and right end portions of the peripheral portion 3 parallel to the longitudinal direction of the gas flow path 2 are bent downward to project the locking pieces 1a. The metal separator 1 is rolled at the center by a press at the time of forming the gas flow path 2. Since the extension of the rolled center part is regulated by the non-rolled peripheral part 3a orthogonal to the longitudinal direction of the gas flow path 2, the entire metal separator 1 is strained in a concave or convex shape with the center part as the center. (See FIGS. 5B and 5C).
[0020]
Next, as a second step, a peripheral portion 3b (between CD and HG) that is parallel to the longitudinal direction of the gas flow path 2 is fixed, and a peripheral portion 3a that is orthogonal to the longitudinal direction of the gas flow path 2 A tensile force in the same direction as the direction (arrow Y direction in FIG. 5) perpendicular to the longitudinal direction of the gas flow path is applied only to the (BCHA portion and DEFG portion).
[0021]
That is, a peripheral portion 3b (between CD and HG) parallel to the longitudinal direction of the gas flow path 2 is fixed with a jig from above and below, and the peripheral portion 3a orthogonal to the longitudinal direction of the gas flow path 2 A cam mold (a mold that opens to the left and right when pressed) is installed at the lower part of the frame, the cam mold is locked to the locking piece 1a, the cam mold is opened to the left and right, and the locking piece 1a is expanded. Thus, only in the peripheral portion 3a (between BCHA and DEFG), a tensile force is applied in the same direction (arrow Y direction in FIG. 5) as the direction orthogonal to the longitudinal direction of the gas flow path (arrow Y direction in FIG. 5). .
[0022]
FIG. 6 shows the state of the metal separator 1 after a tensile force is applied, and the peripheral portion 3a to which the tensile force is applied by pushing and expanding the locking piece 1a with a cam type is the direction in which the tensile force is applied. It is rolled a little.
[0023]
In the second step, the peripheral portion 3a is stretched in a direction perpendicular to the longitudinal direction of the gas flow path, so that the extension of the center portion restricted by the peripheral portion 3a that has not been rolled is released, and the metal separator 1 distortion can be corrected (see FIGS. 6B and 6C).
[0024]
In the second step, the peripheral portion 3b parallel to the longitudinal direction of the gas flow path 2 is fixed, and a tensile force is applied only to the peripheral portion 3a, so that the tensile force is applied to the press-formed gas flow path 2. It is possible to maintain the normal shape of the gas flow path 2 without being affected.
[0025]
And the peripheral part 3 can be cut into a product shape, and the metal separator 1 without a distortion can be obtained. Since the metal separator 1 without distortion can secure a contact area with the stacked anode 5 and cathode 6, the conductivity is improved and the power generation performance of the fuel cell 12 can be improved.
[0026]
Further, the distortion-free metal separator 1 that secures the contact area with each of the electrodes 5 and 6 can improve thermal conductivity and improve the power generation performance of the fuel cell 12. Furthermore, since the gas sealing properties of the stacked cells 7 and the peripheral portions 3a and 3b of the metal separator 1 are also improved, confidentiality is ensured and the performance of the fuel cell 12 is improved.
[0027]
【The invention's effect】
Since the present invention has the above-described configuration, the following effects can be obtained.
In the first aspect of the present invention, after the first step of press-molding the gas flow path, the same direction as the rolling direction in which the gas flow path is formed in the upper and lower peripheral portions orthogonal to the longitudinal direction of the gas flow path. By providing a simple second step of applying a tensile force, the extension of the center part, which is regulated in the non-rolling peripheral part orthogonal to the longitudinal direction of the gas flow path, is released by applying a tensile force to the peripheral part. And the metal separator which has ensured flatness as the whole metal separator, and has no distortion can be obtained.
[0028]
In the second step, the peripheral part parallel to the longitudinal direction of the gas flow path is fixed, and a tensile force is applied only to the peripheral part orthogonal to the longitudinal direction of the gas flow path. The tensile force does not affect the path, and the normal shape of the gas flow path can be maintained to improve the flatness of the entire metal separator.
[0029]
A non-distorted metal separator molded with a normal gas flow path, obtained by providing a simple second process after the first process of press molding the gas flow path, ensures a contact area with the anode and cathode. It is possible to improve the electric power generation performance of the fuel cell using the metal separator by improving the electrical conductivity, the thermal conductivity and the sealing property.
[Brief description of the drawings]
FIG. 1 is a plan view showing a fuel cell.
FIG. 2 is a perspective view showing a structure of a single cell and a metal separator.
FIG. 3 is an explanatory diagram showing a structure in which a plurality of cells are stacked via a metal separator.
FIG. 4 is an explanatory view showing a first step of an embodiment of the present invention.
5A is a plan view of the metal separator after the first step, FIG. 5B is a bottom view, and FIG. 5C is a side view.
6A is a plan view of the metal separator after the second step, FIG. 6B is a bottom view, and FIG. 6C is a side view.
7 shows a conventional example, (a) a plan view of a metal separator after forming a gas flow path, (b) a bottom view, and (c) a side view.
[Explanation of symbols]
1; Metal separator 1 ′; Metal plate 1a; Locking piece 2; Gas flow path 2A; Anode gas flow path 2C; Cathode gas flow path 3; Peripheral part 3a; Peripheral part 3b orthogonal to the longitudinal direction of the gas flow path; Peripheral part 4 parallel to the longitudinal direction of the gas flow path; Electrolyte plate 5; Anode 6; Cathode 7; Cell 8; Seal plate 9; Seal plate 10; Manifold 11; Manifold 12;

Claims (1)

In a method of manufacturing a metal separator for a fuel cell in which a vertically elongated gas flow path for supplying anode gas or cathode gas to anode and cathode electrodes sandwiching an electrolyte is formed, the peripheral portions remain on the left, right, top and bottom of the metal plate Then, a first step of press-molding a vertically elongated gas passage in the center portion and a peripheral portion parallel to the longitudinal direction of the gas passage are fixed and orthogonal to the longitudinal direction of the gas passage The manufacturing method of the metal separator for fuel cells provided with the 2nd process which applies the tensile force of the direction orthogonal to the longitudinal direction of a gas flow path only to a peripheral part.

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