JP2002367624A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell of which, mutual positions of metal separators can be settled with high accuracy. SOLUTION: For the fuel cell 1, having electrode structure 2, formed by arranging an anode electrode 8 and a cathode electrode 9 to both surfaces of an electrolyte 7 held between a pair of metal separators 3, 4, a positioning hole 20, penetrating in the direction of thickness, settling mutual position of respective metal separators 3, 4 by the insertion of a positioning pin 21, is formed to respective metal separators 3, 4, and a guiding part 22, making the positioning hole 20 extend in longitudinal direction, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell having an electrode structure sandwiched between a pair of separators.

[0002]

2. Description of the Related Art In a fuel cell, an electrode structure having an anode electrode and a cathode electrode disposed on both sides of a solid polymer electrolyte membrane, respectively, is formed into a flat plate by sandwiching the electrode structure with a pair of separators. is there. A plurality of the fuel cells configured as described above are stacked in the thickness direction to form a fuel cell stack.

In each fuel cell, a flow path for fuel gas (for example, hydrogen) is provided on one surface of an anode-side separator arranged opposite to an anode electrode, and an oxidant is provided on one surface of a cathode-side separator arranged opposite to a cathode electrode. A gas (for example, air containing oxygen) flow path is provided. Also,
A flow path for a cooling medium (for example, pure water) is provided between adjacent separators of adjacent fuel cells.

[0004] When fuel gas is supplied to the electrode reaction surface of the anode electrode, hydrogen is ionized here and moves to the cathode electrode through the solid polymer electrolyte membrane. The electrons generated during this time are taken out to an external circuit and used as DC electric energy. Since an oxidizing gas is supplied to the cathode electrode, hydrogen ions, electrons, and oxygen react to generate water. On the electrode reaction surface,
Since heat is generated when water is generated, the water is cooled by a cooling medium passed between the separators.

[0005] Separators constituting each fuel cell,
All the separators of the plurality of fuel cells constituting the fuel cell stack properly sandwich the solid polymer electrolyte membrane, and the seal member that partitions each flow path in a liquid-tight or air-tight state by a predetermined portion of the separator. Need to be positioned accurately.

As a method of positioning the stacked separators, for example, JP-A-8-203543, JP-A-9-7627 and JP-A-9-134
As disclosed in Japanese Patent No. 734, a method is adopted in which a knock pin is inserted into a knock hole formed through each separator in the thickness direction so as to penetrate all knock holes of a plurality of stacked separators. Have been.

[0007] As indicated in these publications, conventional separators are made of carbon and have a sufficient thickness to ensure their own strength. Accordingly, the knock hole into which the knock pin is inserted has a sufficient length, and a relatively large contact area between the knock pin and the knock hole can be ensured, so that the separators are accurately positioned.

[0008]

In recent years, in order to reduce the size and weight and reduce the cost by improving the mass production of fuel cells, a thin metal is used instead of the thick carbon as the material of the separator. It is thought that. However, as described above, the metal separator is much thinner than the carbon separator, and therefore, as shown in FIG. However, since the contact length between the knock hole 61 of each metal separator 60 and the knock pin 62 is short, it is difficult to suppress the displacement of the knock pin 62 in the direction of falling with respect to the metal separator 60. For this reason, there has been an inconvenience that it is difficult to accurately position the metal separators 60 with the knock pins 62.

If the metal separators 60 are not positioned accurately, the contact positions between the electrode structure 63 and the metal separator 60 on both sides of the electrode structure 53 are shifted. When the laminate is tightened in the thickness direction, a bias is applied to the electrode structure 63, which may result in a disadvantage that the life of the electrode structure 63 is shortened or the power generation performance is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and enables high-precision positioning of metal separators while reducing the size and weight and reducing the cost by using metal separators. It is intended to provide a fuel cell.

[0011]

In order to achieve the above object, the present invention proposes the following means. Claim 1
The invention described in the above, in a fuel cell in which an electrode structure comprising an anode electrode and a cathode electrode disposed on both surfaces of an electrolyte sandwiched between a pair of metal separators, the metal separators penetrate in the thickness direction, A positioning hole for positioning metal separators by a positioning pin to be inserted is provided, and at least a part of a periphery of the positioning hole in a circumferential direction is provided with a guide portion extending the positioning hole in a length direction. Suggest a battery.

According to the fuel cell of the present invention, a pair of metal separators is laminated with the electrode structure interposed therebetween, and a positioning pin is inserted through a positioning hole provided in each metal separator to thereby insert the metal separator. They are arranged in a state where they are positioned. In this case, the positioning hole is provided at least in part in the circumferential direction with a guide portion extending the positioning hole in the length direction.
It is supported from the side by the guide portion, and displacement in the direction of falling with respect to the metal separator is suppressed.

Therefore, by inserting the positioning pins into the positioning holes, the metal separator can be prevented from being displaced and can be positioned accurately. That is, by arranging the metal separator accurately,
Since the electrode structure is sandwiched between the appropriate portions of the metal separator and the flow path for supplying the fuel gas and the like can be reliably defined, the fuel cell can be easily assembled.

The invention according to claim 2 proposes the fuel cell according to claim 1, wherein the guide portion is formed by burring. According to the fuel cell of the present invention, by forming the guide portion by burring, a cylindrical guide portion is formed around the entire periphery of the positioning hole. Such a guide portion can be easily manufactured by burring as a part of press working, and supports the side surface of the positioning pin inserted into the positioning hole over the entire circumference, so that the metal separator in all directions can be formed. Positional deviation can be prevented, and positioning accuracy can be further improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel cell 1 according to a first embodiment of the present invention will be described with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the fuel cell 1 according to the present embodiment sandwiches the electrode structure 2 between a pair of metal separators (the first separator 3 and the second separator 4), and At a position surrounding the outer periphery, the first separator 3
The first seal member 5 seals the space between the second electrode 4 and the electrode structure 2, and the second seal member 6 seals the space between the second separator 4 and the outer periphery of the electrode structure 2.

The electrode structure 2 is, for example, as shown in FIG. 3, a solid polymer electrolyte membrane 7 made of a perfluorosulfonic acid polymer (hereinafter simply referred to as an electrolyte membrane).
And an anode electrode 8 and a cathode electrode 9 sandwiching both surfaces of the electrolyte membrane 7. For the anode electrode 8 and the cathode electrode 9, for example, a catalyst layer made of an alloy mainly composed of Pt is laminated on one surface of the gas diffusion layer made of porous carbon cloth or porous carbon paper in contact with the electrolyte membrane 7. It is constituted by.

Each of the first separator 3 and the second separator 4 has a certain height as shown in FIG. 3 by pressing a stainless steel plate material having a thickness of 0.2 to 0.5 mm. As shown in FIGS. 1 and 2, a corrugated plate 10 having a large number of irregularities formed in a constant pattern, a fuel gas (for example, hydrogen gas) flowing through the corrugated plate 10, and an oxidizing gas (for example, A fuel gas supply port 1 penetrating through each of the separators 3 and 4 so as to supply and discharge oxygen-containing air) and a cooling medium (for example, pure water).
1. Oxidant gas supply port 12, cooling medium supply port 13, fuel gas discharge port 14, oxidant gas discharge port 15, cooling medium discharge port 16, these supply ports 11 to 13, and discharge port 14 to
16 and a flat portion 17 arranged so as to surround the corrugated plate portion 10, respectively.

As shown in FIGS. 1 and 2, the cooling medium supply port 13 and the cooling medium discharge port 16 are disposed substantially at the center of the separators 3 and 4 in the width direction. The fuel gas supply port 11 and the oxidant gas supply port 12
Are separated by the separators 3 and 4 with the cooling medium supply port 13 interposed therebetween.
Are arranged on both sides in the width direction. Further, the fuel gas outlet 14 and the oxidizing gas outlet 15 are arranged on both sides in the width direction of the separators 3 and 4 with the cooling medium outlet 16 interposed therebetween. The fuel gas outlet 14 and the oxidizing gas outlet 15 are arranged diagonally to the fuel gas supply port 11 and the oxidizing gas supply port 12, respectively.

In FIG. 1 and FIG.
Are sandwiched between the first separator 3 and the second separator 4 to supply various kinds of supply ports 11 to 13 and discharge ports 14 to 16.
And a third seal member and a fourth seal member that seal the periphery of the third seal member. In FIG. 3, reference numeral 24 denotes a fifth seal member for sealing between adjacent fuel cells 1. In addition, various supply ports 11 to 13 and discharge ports 14 to
Numeral 16 communicates with the respective flow paths defined in the corrugated plate portion 10 by a communication portion (not shown) so that the fuel gas, the oxidizing gas, and the cooling medium can flow around the electrode structure 2. ing.

The flat portion 17 has a pair of metal separators 3 and 4 constituting one fuel cell 1 and a knock hole 20 (positioning hole) for positioning a plurality of stacked fuel cells 1. ) Is provided. The knock holes 20 are provided at two locations, one at each end of the metal separators 3 and 4. As a result, as shown in FIG.
Is inserted, the relative translation of the metal separators 3 and 4 is prevented, and the metal separators 3 and 4 are inserted.
The relative rotational movement of the four members is also prevented. In FIG. 3, for clarity, dowel holes 20
The description of the third and fourth seal members 18 and 19 disposed around the periphery is omitted.

As shown in FIG. 3, the dowel hole 20 is subjected to a burring process to form a cylindrical guide portion 22 over the entire periphery of the dowel hole 20. That is, the flat metal separators 3, 4
The corrugated plate portion 10, the various supply ports 11 to 13 and the discharge ports 14 to 16 are formed by press working, and a punch is pressed into a prepared hole for the knock hole 20 punched out in this press working step. The guide portion 22 is formed by a burring process of forming a cylindrical flange while widening the hole diameter with
Is formed.

The cylindrical guide portion 22 has a cylindrical inner surface 22a that extends the inner diameter of the knock hole 20 in the longitudinal direction. When the knock pin 21 is inserted into the knock hole 20, the side surface of the knock pin 21 is formed. It is configured so as to be in close contact with the cylindrical inner surface 22a of the cylindrical guide portion 22.

The guide part 22 is provided with the first separator 3.
In order to avoid an electrical short circuit between the first and second separators 4, the height of the second separator 4 is smaller than the distance between the separators 3 and 4. That is, as shown in FIG.
When the electrode structure 2 is sandwiched between the first separator 3 and the second separator 4, the knock holes 20 formed in the first separator 3 and the knock holes 20 formed in the second separator 4 are aligned. Although the guides 22 are arranged side by side, the height of the guides 22 is smaller than the distance between the separators 3 and 4, so that the tip of the guides 22 of one metal separator 3 is connected to the other metal separator. The contact between the separators 4 and 4 is prevented, and the separators 3 and 4 are kept separated.

The fuel cell 1 according to the present embodiment, which is configured as described above, forms a fuel cell stack 23 by being stacked in the thickness direction. Metal separator 3 for each fuel cell 1
4 are arranged in a line, so that the knock pins 21 penetrating all the knock holes 20 are formed.
Is inserted, the plurality of metal separators 3 and 4 are arranged in a mutually positioned state. The knock pin 21
In order to prevent electrical conduction between the metal separators 3 and 4, it is preferable that the separators be made of an insulating material such as a resin, for example.

In this case, in the fuel cell 1 according to the present embodiment, the cylindrical guide portion 2
2, the side surface of the knock pin 21 inserted into the knock hole 20 comes into close contact with the cylindrical inner surface 22a of the guide portion 22 over the entire circumference. Inner cylindrical surface 2 of guide portion 22
2a has a length sufficiently longer than the plate thickness of the metal separators 3 and 4, so that the knock pin 21 has a large contact as if it were inserted into the knock hole of the thick separator. It can contact the metal separators 3 and 4 in area.

That is, the knock pin 21 is supported from the side by the guide portion 22 provided on the metal separators 3 and 4 over the entire circumference, and is held so as not to fall on the metal separators 3 and 4. Therefore, even if a force for shifting one metal separator 3 in the plane direction with respect to the other metal separator 4 acts, the falling of the knock pin 21 is suppressed by the guide portion 22, and the misalignment between the metal separators 3 and 4 is caused. Does not occur.

In addition, according to the fuel cell 1 of the present embodiment, the cylindrical guide portion 22 formed by bending the periphery of the knock hole 20 of the metal separators 3 and 4 by burring is formed by the cylindrical guide portion 22. Since it functions as a rib for reinforcing the edge, deformation of the edge of the knock hole 20 due to contact with the knock pin 21 when the knock pin 21 is inserted can be prevented. That is, it is possible to prevent a decrease in positioning accuracy due to deformation of the knock hole 20.

Next, a fuel cell 30 according to a second embodiment of the present invention will be described with reference to FIG. In addition,
In the following description, portions having the same configuration as the fuel cell 1 according to the above-described first embodiment will be denoted by the same reference numerals, and the description will be simplified.

The fuel cell 30 according to the present embodiment differs from the fuel cell 1 according to the first embodiment in the structure of the guide portion 31.
Is different. The guide portion 31 in the fuel cell 30 of the present embodiment is an annular member formed separately from the metal separators 3 and 4. The guide portion 31 has a large diameter portion 31a and a small diameter portion 31b in the thickness direction.
b is formed to have an outer diameter dimension that fits exactly into the through holes 32 formed in the metal separators 3 and 4. on the other hand,
The large-diameter portion 31a is configured to abut on the surfaces of the metal separators 3, 4 in a state where the small-diameter portion 31b is completely fitted in the through hole 32, and to position the guide portion 31 in the thickness direction. .

The thickness of the guide portion 31 is formed sufficiently longer than the thickness of the metal separators 3 and 4, and the inner cylindrical surface 31 c of the guide portion 31 has a knock hole 20 that contacts the outer surface of the knock pin 21. Make up. The guide part 31
The metal separators 3 and 4 are attached to the metal separators 3 and 4 by an arbitrary joining method such as adhesion, welding, and brazing. Further, when the knock pin 21 is a knock pin 21 made of the same insulating material as that of the first embodiment, the guide portion 31 is not limited in its material, but is used when the knock pin 21 made of a conductive material is used. Must be made of an insulating material such as resin.

According to the fuel cell 30 according to the present embodiment having the above-described configuration, similarly to the burring-processed guide portion 22 in the first embodiment, the fuel cell 30 is provided on the entire circumference of the knock hole 20 in the circumferential direction. By extending the knock hole 20 in the length direction by the guide portion 31, the knock pin 21 is extended.
Can be greatly increased, and the side surface of the knock pin 21 can be supported over the entire circumference, so that the knock pin 21 can be prevented from falling with respect to the metal separators 3 and 4 and metal can be prevented. The separators 3 and 4 can be positioned accurately. Further, such an improvement in the positioning accuracy can be achieved by using the annular guide member 30.
This can be achieved by an extremely simple configuration.

Next, a fuel cell 40 according to a third embodiment of the present invention will be described with reference to FIG. The fuel cell 40 according to this embodiment also has the structure of the guide portion 41 in the fuel cells 1 and 3 according to the first and second embodiments.
0. The guide portion 41 of the fuel cell 40 according to the present embodiment is formed in an annular shape, and has a peripheral groove 42 depressed by one step at the center of the outer surface in the thickness direction. The groove width dimension of the peripheral groove 42 matches the thickness dimension of the metal separators 3 and 4, and the edge of the through-hole 20 formed in the metal separators 3 and 4 is accommodated in the peripheral groove 42 so that the guide portion is formed. Is 41
They are fixed to metal separators 3 and 4.

The metal separator is made of, for example, a resin, and is attached to the edge of the through hole 43 of the metal separators 3 and 4 by bonding or the like.
4 may be integrally formed. According to the fuel cell 40 according to the present embodiment configured as described above, similarly to the fuel cells 1 and 30 according to the first and second embodiments, it is possible to prevent the knock pin 21 from falling with respect to the metal separators 3 and 4. Thus, the metal separators 3 and 4 can be accurately positioned.

Next, a fuel cell 50 according to a fourth embodiment of the present invention will be described with reference to FIG. The fuel cell 50 according to this embodiment has a guide portion 51 formed by curving the periphery of the through hole 20 formed in the metal separators 3 and 4.
The fuel cell 1 according to the first embodiment is common to the fuel cell 1 according to the first embodiment in that the metal separators 3 and 4 are formed over the entire circumference of the through hole 20 by burring. Cylindrical guide 2 projecting to one side
2 is different from the second embodiment in that a guide portion 51 protruding from both sides of the metal separators 3 and 4 is provided.

In the fuel cell 50 of the present embodiment, as shown in FIG. 6, a plurality of cuts 52 are formed in the radial direction from the peripheral edge of the through hole 20 formed in the metal separators 3, 4, and the cuts 52 are formed. As shown in FIG. 7, the plurality of divided pieces 53 are alternately bent on one side and the other side of the metal separators 3 and 4 to form a knock hole having a guide portion 51 over the entire circumference. 2
0 is formed.

Since the guide portion 51 thus configured has a length approximately twice as long as each of the divided pieces 53, the knock hole 20 is extended in the length direction, and The knock pin 21 is provided on the side of the knock pin 21 to be inserted.
Can be contacted over a wide range in the longitudinal direction. As a result, it is possible to more effectively prevent the knock pin 21 from falling down and achieve high positioning accuracy.

The fuel cells 1 and 2 according to the above embodiments
In 30, 40, and 50, the case where the guide portions 22, 31, 41, and 51 are provided around the entire periphery of the knock hole 20 has been described, but the present invention is not limited to this. That is, the guide portion may be provided partially on the peripheral edge of the knock hole 20 in a part in the circumferential direction. For example, it may be provided at several places at intervals in the circumferential direction of the periphery of the knock hole 20. In this case, since the knock pin 21 is prevented from falling in the direction in which the guide portion is provided,
As long as it is effective. Further, in this case, if the phase of the guide portion is shifted for each of the metal separators 3 and 4, the falling of the knock pin 21 can be supported in all directions.

[0038]

As is clear from the above description, the present invention has the following effects. (1) According to the fuel cell according to the first aspect of the present invention, the positioning pin is supported from the side by the guide portion provided on at least a part of the periphery of the positioning hole.
The positioning pins are held so as not to fall with respect to the metal separator, and as a result, the metal separators can be positioned with high accuracy. By positioning the metal separators with high precision, an excessive biasing force is prevented from acting on the electrode structure sandwiched between these metal separators, so that the soundness of the electrode structure is maintained and the fuel cell is maintained. In addition to the above, there is an effect that a reduction in the life of the battery can be prevented, and a reduction in the power generation performance can be prevented. Furthermore, since the displacement of the metal separator due to the falling of the positioning pin can be prevented, the effect of minimizing the fluctuation of the outer diameter of the fuel cell can be obtained. (2) According to the fuel cell according to the second aspect of the present invention, since the guide portion is formed by burring, the guide portion can be easily formed as part of the pressing of the metal separator. Therefore, there is an effect that a fuel cell in which the metal separator is positioned with high precision can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing components of a fuel cell according to a first embodiment of the present invention.

FIG. 2 is a plan view schematically showing a state where components of the fuel cell of FIG. 1 are combined.

FIG. 3 is a longitudinal sectional view showing the vicinity of a knock hole portion of the fuel cell of FIG. 2;

FIG. 4 is a longitudinal sectional view partially showing a vicinity of a knock hole of a fuel cell according to a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional view partially showing a vicinity of a knock hole of a fuel cell according to a third embodiment of the present invention.

FIG. 6 is a plan view partially showing the vicinity of a knock hole of a fuel cell according to a fourth embodiment of the present invention.

FIG. 7 is a longitudinal sectional view partially showing the vicinity of a knock hole in FIG. 6;

FIG. 8 is a longitudinal sectional view partially showing a vicinity of a knock hole of a conventional fuel cell.

[Explanation of symbols]

 1, 30, 40, 50 Fuel Cell 2 Electrode Structure 3 First Separator (Metal Separator) 4 Second Separator (Metal Separator) 7 Electrolyte Membrane (Electrolyte) 8 Anode Electrode 9 Cathode Electrode 21 Dowel Pin (Positioning Pin) 20 Dowel Hole (Positioning holes) 22, 31, 41, 51 Guide section

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideaki Kikuchi 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. 5H026 AA06 CC03 EE02 HH03

Claims (2)

[Claims] 1. A fuel cell in which an electrode structure comprising an anode and a cathode disposed on both surfaces of an electrolyte is sandwiched between a pair of metal separators. A fuel cell having a positioning hole for positioning the metal separators with each other by a positioning pin to be provided, and a guide portion extending in a length direction of the positioning hole at least at a part of a periphery of the edge of the positioning hole. . 2. The fuel cell according to claim 1, wherein the guide portion is formed by burring.