JP2003151571A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell, in which positioning of an interlayer in a separator is easy, while securing flexibility of displacement of the interlayer arranged between the separator. SOLUTION: The fuel cell 20 is constituted by laminating a plurality of film electrode structure components 24, which is constituted by sandwiching a solid high polymer electrolyte film 21 with a pair of electrodes 22 and 23, through the separators 25 and 26. The interlayer 36, which is provided in the separators 25 and separates the cooling medium flow ways 37 of its both sides, is fixed to a fitting hole 39 prepared in the interlayer 36 by fitting it to an elastic projection 40 of the separator 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell in which a plurality of electrode structures having an electrolyte sandwiched between a pair of electrodes are laminated with a separator interposed therebetween.

[0002]

2. Description of the Related Art A fuel cell constituting a fuel cell is
2. Description of the Related Art There is a solid polymer electrolyte membrane having a flat plate shape in which a membrane electrode structure in which an anode electrode and a cathode electrode are arranged on both sides is sandwiched between a pair of separators. A plurality of the fuel cells configured as described above are stacked in the thickness direction to form a fuel cell.

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

Then, when the fuel gas is supplied to the electrode reaction surface of the anode electrode, hydrogen is ionized there, and the hydrogen ions move to the cathode electrode through the solid polymer electrolyte membrane. The electrons generated during this period are taken out to an external circuit and used as direct current electrical energy. Since the oxidant gas is supplied to the cathode electrode, hydrogen ions, electrons, and oxygen react with each other to generate water. At the electrode reaction surface, heat is generated when water is generated, so that the electrode reaction surface is cooled by a cooling medium that is circulated between the separators.

In the fuel cell as described above, the separator is generally made of carbon which is excellent in electrical characteristics such as conductivity and corrosion resistance and is also excellent in accuracy. Has a problem that the thickness becomes large and the strength and productivity are low. From such a point, the use of a metal separator that can be formed by press working and is thin and has high productivity has been studied, and a technique relating to a metal separator has already been disclosed (Japanese Unexamined Patent Application Publication No. 20-200200).
No. 00-21419).

That is, a fuel cell using a metal separator has a membrane electrode structure having an anode electrode 2 and a cathode electrode 3 on both sides of a solid polymer electrolyte membrane 1 as shown in the sectional view of FIG. 4 has a fuel cell 7 formed by disposing a pair of corrugated metal separators 5 and 6 on both sides. A plurality of such fuel cells 7 are stacked so that the convex portions 8 and 9 of the adjacent metal separators 5 and 6 are butted and the concave portions 10 and 11 are opposed to each other, whereby the fuel cell is configured. is there. Then, the recesses 10, 1 facing the metal separators 5, 6
The space between the two is a cooling medium flow path 12, and the space between the concave portion 13 on the back side of the convex portion 8 of the metal separator 5 and the anode electrode 2 is a fuel gas flow path 14.
The space between the concave portion 15 on the back side of the convex portion 9 and the cathode electrode 3 serves as an oxidant gas flow channel 16.

[0007]

However, since the metal separator formed by press working is thin, shape errors such as warpage and waviness are likely to occur, and if used as it is, the flatness of the metal separator is ensured. Is difficult. In particular, when a fuel cell is formed by fastening a plurality of stacked fuel cells in the stacking direction, when a tightening load is applied to the fuel cells, the shape error of the metal separator accumulates and the fuel cells warp. The undulation may occur, and as a result, the surface pressure applied to the electrode surface of the adjacent anode electrode or cathode electrode may become uneven. Then, the contact resistance increases and the internal resistance of the fuel cell increases, which may make it difficult to obtain the desired performance.

Therefore, by providing an intermediate plate (for example, a leaf spring) made of an elastic member between the separators, the warp, undulation, etc. generated in the fuel cell unit are absorbed, and a proper surface pressure is applied to the fuel cell unit. Is being considered.

When such an intermediate plate is used, if the intermediate plate is made smaller than the separator in consideration of downsizing and weight saving of the fuel cell, it is difficult to position the separator in the separator, while a knock pin or the like separates the separator. However, there is a problem in that the degree of freedom of displacement of the intermediate plate is impaired, and it becomes difficult to absorb the above-described warpage and undulations.

The present invention has been made in view of the above circumstances, and provides a fuel cell in which an intermediate plate provided between separators ensures a certain degree of freedom of displacement and is easily positioned in the separator. With the goal.

[0011]

In order to solve the above problems, the invention described in claim 1 provides an electrolyte (for example, the solid polymer electrolyte membrane 21 in the embodiment) with a pair of electrodes (for example, the embodiment). A plurality of electrode structures (for example, the membrane electrode structure 24 according to the embodiment) sandwiched between the anode electrode 22 and the cathode electrode 23 according to the embodiment are stacked via a separator (for example, the separators 25 and 26 according to the embodiment). In the fuel cell according to the present invention, the intermediate plate (for example, the intermediate plate 36 in the embodiment) provided in the separator and defining the flow paths on both sides (for example, the cooling medium flow path 37 in the embodiment) is By engaging the elastic protrusion (for example, the elastic protrusion 40 in the embodiment) of the separator with the hole provided in the plate (for example, the engaging hole 39 in the embodiment). A fuel cell, characterized in that the fixing.

According to this structure, the intermediate plate is fixed to the elastic projection, and the elastic projection can expand and contract within a certain range, so that the intermediate plate can slide with respect to the separator. Therefore, the warp and swell of the separator, the electrode structure, and the fuel cell can be absorbed. Further, since the intermediate plate is provided inside the fuel cell, there is no risk of increasing the thickness in the stacking direction, and it does not hinder the downsizing and weight reduction of the fuel cell.

The intermediate plate can be applied not only when partitioning the cooling flow path but also when partitioning the gas flow path. Further, the elastic protrusion can be installed by adhering or baking on the separator. The fuel cell may be any of solid polymer type, solid electrolyte type, alkaline type, phosphoric acid type, and molten carbonate type.

According to the second aspect of the present invention, the elastic member (for example, the elastic projection 51 in the embodiment) is integrally formed with the seal member (for example, the cooling surface sealing member 52 in the embodiment) provided between the separators. Is a fuel cell.

With this structure, the elastic protrusions can be made of the same material as the seal member and can be placed together with the seal member at one time, so that the molding process can be facilitated and the number of parts can be reduced. Therefore, the cost can be reduced.

The invention according to claim 3 is characterized in that the elastic protrusion (for example, the elastic protrusion 61 in the embodiment) is provided with a retaining portion (for example, the retaining portion 62 in the embodiment). It is a fuel cell that does. With this structure, the intermediate plate can be prevented from falling off the elastic protrusion, and the reliability of the intermediate plate can be improved.

[0017]

DETAILED DESCRIPTION OF THE INVENTION A fuel cell according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of essential parts showing a fuel cell according to a first embodiment of the present invention. The fuel cell 20 is provided with a membrane electrode structure 24 constituted by arranging an anode electrode 22 and a cathode electrode 23 so as to sandwich the solid polymer electrolyte membrane 21 on both sides in the thickness direction. Then, the membrane electrode structure 2
4 is further sandwiched between a pair of metallic separators 25 and 26, and a plurality of fuel battery cells 27 are stacked, and electric power is taken out from both ends of the stacked fuel battery cells 27.

The metal separators 25 and 26 are, for example, a pair formed by punching and bending a stainless steel plate material having a plate thickness of 0.1 to 0.5 mm by press working. Recess 28 in the center
Is provided with a corrugated plate portion 30 in which convex portions and convex portions 29 are alternately arranged, and the metallic separator 26 has a corrugated sheet portion in which convex portions 31 and concave portions 32 are alternately arranged at the center portions thereof. Part 33
Is provided. The metal separators 25, 26
As the material of the above, it is possible to use stainless steel or a material obtained by coating the surface of stainless steel with a material having corrosion resistance.

In the metallic separator 25, the plurality of concave portions 28 are brought into contact with the anode electrode 22, and the plurality of convex portions 2 are formed.
9 is arranged so as to face the anode electrode 22. In addition, the metal separator 26 has a plurality of convex portions 3
1 is brought into contact with the cathode electrode 23, and a plurality of recesses 32
Are arranged so as to face the cathode electrode 23.

An intermediate plate 36 is provided between the separators 25 and 26.
Has been installed. The intermediate plate 36 is made of a smooth metal plate and elastically deforms when a load is applied, and gives an elastic force when the load is removed and the shape returns to the original shape.
This elastic urging secures electrical contact between the separators 25 and 26, and thus between the fuel cells 27.
This will be described in detail later.

A space between the anode electrode 22 and the convex portion 29 of the metallic separator 25 adjacent to the anode electrode 22 serves as a fuel gas flow passage 34, and hydrogen gas is supplied to the fuel gas flow passage 34. On the other hand, the space between the cathode electrode 23 and the concave portion 32 of the metal separator 26 adjacent to the cathode electrode 23 serves as an oxidant gas passage 35, and air is supplied to the oxidant gas passage 35. In addition, the recess 28 of the metal separator 25 and the intermediate plate 3
6 and the space between the convex portion 31 of the metal separator 26 and the intermediate plate 36 are used as a cooling medium flow channel 37, and the cooling liquid is supplied to the cooling medium flow channel 37, so that the membrane electrode The structure 24 is adapted to be cooled.

A cooling face seal member 38 is provided between the separators 25 and 26 to seal the peripheral edges of the separators 25 and 26. In addition, the membrane electrode structure 24
A gas seal member (not shown) is provided between the separator and the separators 25, 26, and the membrane electrode structure 24 and the separator 2 are provided.
5 and 26 are provided with communication holes (not shown) through which reaction gas and cooling liquid are supplied or discharged, but description thereof will be omitted.

The intermediate plate 36 is composed of the separators 25, 26.
The plane size is smaller than that of the separators 25, 2
It is provided inside the cooling face seal member 38 between the six. The cooling medium passage 37 formed between the separators 25 and 26 is partitioned by the cooling surface seal member 38. Further, an engaging hole 39 is formed in the peripheral edge of the intermediate plate 36, and the engaging hole 39 engages with a rubber elastic protrusion 40 arranged inside the cooling surface sealing member 38. ing. As a result, the intermediate plate 36 is fixed to the elastic protrusions 40 and thereby positioned and held between the separators 25 and 26. Further, due to the nature of the elastic projection 40, the intermediate plate 36 has a degree of freedom that allows it to move following the displacement of the separators 25 and 26. In this embodiment, in order to position the intermediate plate 36, two engaging holes 39 are provided on the outer periphery of the intermediate plate 36. Further, the intermediate plate 36 has a step portion 41 formed between the outer peripheral portion in which the engagement hole 39 is formed and the inside thereof.
Since the step portion 41 is formed on the intermediate plate 36 as described above, the engaging hole 39 can be engaged with the base end side (back side) of the elastic protrusion 40, so that the engaging hole 39 is formed.
There is no risk of the intermediate plate 36 coming off easily, and the intermediate plate 36 can be more reliably positioned and held.

Thus, even when the separators 25, 26 and the membrane electrode structure 24 undergo thermal expansion along the stacking direction during operation of the fuel cell 20, the intermediate plate 36 is elastic at this time. Deformed and abutted separator 2
5 and 26 are blasted. Therefore, it is possible to uniformly maintain the surface pressure applied to the electrode surfaces of the anode electrode 22 and the cathode electrode 23 adjacent to the separators 25 and 26. Since the increase in the internal resistance of the fuel cell 20 due to the increase in the contact resistance can be suppressed, it is possible to obtain the desired performance sufficiently from the fuel cell 20.

Further, when the operation of the fuel cell 20 is stopped and the temperature drops and the fuel cell 27 contracts along the stacking direction, the intermediate plate 36 returns to its original shape. At this time, the intermediate plate 36 elastically urges the separators 25 and 26. That is, the separators 25 and 26 are pressed by the intermediate plate 36, whereby the pressure holding force for the fuel cell 27 is maintained. Similarly, when so-called fatigue occurs in the fuel cell 27, the intermediate plate 36 elastically urges the separators 25 and 26 to maintain the pressure holding force for the fuel cell 27. further,
Even when a shape error such as warpage or waviness occurs in the separators 25 and 26, the intermediate plate 36 applies an elastic force to the separators 25 and 26 in a direction in which the separators 25 and 26 have an appropriate shape. 26 and the membrane electrode structure 24,
Eventually, the warp and swell of the fuel cell 27 can be absorbed. Further, since the intermediate plate 36 is fixed to the elastic projection 40, even if the intermediate plate 36 is deformed as described above, it can be returned to the predetermined position again.

In this way, the intermediate plate 36 serves as the separator 2
5 and 26 are positioned while ensuring the degree of freedom of displacement to the predetermined positions, the deformations that occur in the separators 25 and 26, the membrane electrode structure 24, and the fuel cell 27 (the above-mentioned thermal expansion and thermal contraction). The intermediate plate 36 can absorb a dimensional change due to a sag, a shape error, or the like. Further, since the intermediate plate 36 is positioned inside the fuel cell, this does not hinder the downsizing and weight reduction of the fuel cell 20.

Next, the fuel cell 50 according to the second embodiment will be described with reference to FIG. In the following description, the same members as those in the above-mentioned embodiment will be designated by the same reference numerals and the description thereof will be omitted as appropriate. The fuel cell 50 shown in the cross-sectional view of FIG. 2 is different from the fuel cell 2 in that the elastic protrusion 51 is integrally formed with the cooling surface seal member 52.
It is different from 0. Because of this, the elastic protrusion 51
Since the same material as that of the cooling surface sealing member 52 can be used and can be arranged together with the cooling surface sealing member 52, the molding process can be facilitated and the number of parts can be reduced.

Next, the fuel cell 60 according to the third embodiment will be described with reference to FIG. The fuel cell 60 shown in the cross-sectional view of FIG. 3 is different from the fuel cell 50 in that the elastic protrusion 61 has a retaining portion 62. Because of this, even if the intermediate plate 36 moves in the stacking direction, the engagement hole 39 portion does not come off the retaining portion 6.
Since the intermediate plate 36 is held in contact with the second plate 36, the intermediate plate 36 can be held more reliably, so that the reliability of the intermediate plate 36 can be improved.

Next, the fuel cell 70 according to the fourth embodiment will be described with reference to FIG. In the fuel cell 70 shown in the sectional view of FIG. 4, a separator 71 is further provided in addition to the separators 25 and 26. The separator 71 has a plurality of protrusions 72,
Of the separator 25, the plurality of recesses 73 are arranged so as to face the protrusions 29 of the separator 25 and contact the anode electrode 22. Because of this, in addition to the fuel gas passage 34 formed in the space between the intermediate plate 36 and the recess 28 of the separator 25,
The fuel gas flow path 74 can be formed in the space between the convex portion 72 of the separator 71 and the anode electrode 22. In this way, by providing the intermediate plate 36, different fuel gas flow paths 34, 74 can be formed in the stacking direction,
The fuel gas can be turned back and flow between these flow paths. The recess 73 of the separator 71 and the separator 25
A cooling medium flow path 75 is formed in a space between the convex portion 29 and the convex portion 29. Further, although the case where the fuel gas flow path is folded back has been described in the present embodiment, it is needless to say that the present invention can be applied to the case where the oxidant gas flow path is folded back.

In the above embodiments, the case where the separator is made of metal has been described, but the separator is not limited to this and may be made of carbon. Also,
The intermediate plate has been described as having a size smaller than that of the separator, but may have a size equal to or larger than that of the separator as long as the size and weight of the fuel cell are not hindered. Further, as described above, in order to prevent deformation of the fuel cell due to thermal expansion, thermal contraction, fatigue, shape error, etc., it is preferable to use an elastic member such as a leaf spring, but it is used as a mere spacer. If so, it need not be an elastic member.

[0031]

As described above, according to the invention described in claim 1, it is possible to prevent the separator, the electrode structure and the fuel cell from being deformed. Further, since the intermediate plate is provided inside the fuel cell, there is no risk of increasing the thickness in the stacking direction, and it does not hinder the downsizing and weight reduction of the fuel cell.

According to the second aspect of the present invention, the same material as that of the seal member can be used and they can be arranged at one time, so that the molding process can be facilitated and the number of parts can be reduced.

According to the third aspect of the invention, it is possible to prevent the intermediate plate from falling off the elastic protrusion, and it is possible to enhance the reliability of the intermediate plate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a fuel cell according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a fuel cell according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts showing a fuel cell according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts showing a fuel cell according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts showing a conventional fuel cell.

[Explanation of symbols]

20 fuel cells 21 Solid polymer electrolyte membrane 22 Anode electrode 23 Cathode electrode 24 membrane electrode structure 25,26 separator 36 Intermediate plate 37 Cooling medium flow path 39 Engagement hole 40, 51, 61 elastic protrusions 62 retaining part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Tanaka             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory (72) Inventor Toshiya Wakaho             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory (72) Inventor Keisuke Ando             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory F-term (reference) 5H026 AA06 CC03 CX08

Claims (3)

[Claims] 1. A fuel cell in which a plurality of electrode structures in which an electrolyte is sandwiched between a pair of electrodes are stacked with a separator interposed therebetween, wherein an intermediate plate that is provided in the separator and defines flow passages on both sides is provided. A fuel cell characterized by being fixed by engaging an elastic protrusion of a separator with a hole provided in an intermediate plate. 2. The fuel cell according to claim 1, wherein an elastic protrusion is integrally formed on a seal member provided between the separators. 3. The fuel cell according to claim 1, wherein the elastic protrusion has a retaining portion.