JP2007250297A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve flow efficiency and diffusion efficiency of a reaction gas in a gas passage. <P>SOLUTION: The gas passage 28 is formed by stacking a second expand metal 31 different by 90° in the arrangement direction of mesh from the mesh 300 of a first expand metal 30 on the first expand metal 30. The reaction gas collides with bond parts 302 of the first expand metal 30 and strand parts 311 of the expand metal 31 while properly flowing through openings 303 of the first expand metal 30 and openings 313 of the second expand metal 31 in the surface direction, flows toward a normal direction, and diffused to an MEGA 25. Since the meshes of the adjacent expand metals are different from each other by 90°, formation of a barrier by overlap between the meshes to match each other can be suppressed in the gas passage 28, whereby gas flow efficiency can be improved, and power generation efficiency of this fuel cell can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell, and more particularly to the configuration of a fuel gas flow path.

  In recent years, fuel cells that generate electricity by an electrochemical reaction between hydrogen gas and oxygen have attracted attention as energy sources. In a fuel cell, a membrane electrode assembly in which an electrode catalyst layer is formed on a solid polymer electrolyte membrane, a separator, and a gas flow path disposed between the membrane electrode assembly and the separator are integrally configured. A plurality of stacked stacks. The gas flow path feeds a reaction gas used for power generation of the fuel cell, such as hydrogen gas or air, into the membrane electrode assembly.

  The gas flow path is configured, for example, by stacking a plurality of expanded metals in which through holes having the same shape are regularly formed in a metal plate. Each side forming the through hole of the expanded metal is called a strand part, and a part where the strand part intersects is called a bond part. The gas flow channel circulates the reaction gas in the surface direction from the through hole of the stacked expanded metal to the through hole. The reaction gas flowing through the gas flow path collides with the strand part or bond part of the expanded metal and is diffused to the electrode catalyst layer.

JP 2004-511667 A JP-A-8-138701 JP-A-11-162480

  However, when a plurality of expanded metals having through-holes having the same shape are stacked, if the through-holes of each expanded metal overlap with each other, the partition walls of the overlapping through-holes are bonded to each other by the strand part and bond part. And the flow of the reaction gas in the surface direction may be hindered. Even if the through-holes of the expanded metal are stacked vertically and horizontally so that the through-holes of each expanded metal do not overlap, the shape of each through-hole of the expanded metal varies due to manufacturing errors, There is a possibility that the through holes of the laminated expanded metal overlap so that they coincide with each other, a partition wall is formed and the flow of the reaction gas is hindered.

  The problem described above is not a problem that occurs only in a gas flow path configured by stacking expanded metals, but common to gas flow paths configured by stacking members in which through holes having the same shape are regularly arranged. It is a problem to do.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to improve the reaction gas flow efficiency and diffusion efficiency in a gas flow path configured by stacking members in which through holes are regularly arranged. .

  In order to solve at least a part of the above-described problems, the present invention provides a fuel cell having a gas flow path formed by laminating a plurality of metal plates each having a through hole that forms a gas flow path. The fuel cell of the present invention includes a separator, a membrane electrode assembly in which a catalyst electrode layer is formed on both surfaces of an electrolyte membrane, and the same that is disposed between the membrane electrode assembly and the separator to form a gas flow path A first gas flow path forming hole having a shape is arranged in a first direction between a first metal plate regularly arranged in a plurality of rows and between the membrane electrode assembly and the first metal plate. The second metal plate in which the second gas channel forming holes having the same shape as the first gas channel forming holes are regularly arranged in a plurality of rows in a second direction different from the first direction. It is a summary to provide.

  According to the fuel cell of the present invention, the gas flow path formation holes of the first metal plate and the second metal plate that are adjacent to each other have different directions, so that the gas flow path formation holes of the metal plates overlap each other. This can be suppressed. Therefore, the distribution efficiency of the reaction gas in the surface direction of the metal plate can be improved, and the diffusion efficiency of the reaction gas to the membrane electrode assembly can be improved.

  In the fuel cell of the present invention, the first gas flow path forming hole and the second gas flow path forming hole have a long diameter and a short diameter, and the long diameter of the first gas flow path forming hole is the first diameter. The major axis of the second gas flow path forming hole may be parallel to the second direction. According to the fuel cell of the present invention, the first gas flow path forming hole and the second gas flow path forming hole have a major axis and a minor axis, and the direction of the major axis of each gas channel forming hole is different, so that they are adjacent to each other. The probability that the gas flow path forming holes of the metal plate overlap each other can be reduced.

  In the fuel cell of the present invention, the shape of the first gas flow path forming hole and the second gas flow path forming hole may be rhombus. According to the fuel cell of the present invention, the gas flow path forming hole can be easily formed.

  In the fuel cell of the present invention, the second direction may be 90 degrees different from the first direction. According to the fuel cell of the present invention, since the direction of the gas flow path forming hole of the adjacent metal plate is different by 90 degrees, the formation of the partition wall due to the overlapping of the through holes of the adjacent metal plate can be suppressed with high probability.

  In the fuel cell of the present invention, a third gas flow path forming hole, which is disposed between the second metal plate and the membrane electrode assembly and has the same shape as the second gas flow path forming hole, is further provided. You may provide the 3rd metal plate regularly arranged over several rows in the 3rd direction different from a direction.

  According to the fuel cell of the present invention, the diffusion efficiency of the reaction gas can be improved by increasing the number of metal plates disposed between the membrane electrode assembly and the separator.

  In the fuel cell according to the present invention, a fourth gas flow path forming hole, which is disposed between the second metal plate and the membrane electrode assembly and has a shape in which the second gas flow path forming hole is reduced, is further provided. You may provide the 4th metal plate regularly arranged in the 4th direction different from 2 directions.

  According to the fuel cell of the present invention, since the fourth gas flow path forming hole disposed adjacent to the membrane electrode assembly is small, the efficiency of gas diffusion into the membrane electrode assembly can be improved.

  The fuel cell according to the present invention may further include a gas diffusion layer that is disposed between the membrane electrode assembly and the second metal plate and is formed of a conductive porous member.

  According to the fuel cell of the present invention, since the gas diffusion layer is disposed between the membrane electrode assembly and the second metal plate, the efficiency of gas diffusion into the membrane electrode assembly can be improved.

  In the fuel cell of the present invention, the separator may be a three-layer stacked separator formed by stacking three conductive plates having conductivity. According to the fuel cell of the present invention, since the gas flow path is formed by the metal plate, the gas flow efficiency can be improved without forming the gas flow path in the separator.

  In the fuel cell of the present invention, each metal plate may be an expanded metal. Expanded metal is lightweight, strong, and can be manufactured at low cost, and according to the fuel cell of the present invention, a durable gas flow path can be provided at low cost.

  In the present invention, the various aspects described above can be applied by appropriately combining or omitting some of them.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on examples with appropriate reference to the drawings.

A. Example:
A1. Fuel cell schematic configuration:
A schematic configuration of the fuel cell 1000 of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell 1000 in the first embodiment. FIG. 2 is a cross-sectional view of the fuel cell 10 according to the second embodiment taken along the line AA of FIG. A fuel cell 1000 according to this embodiment is a solid polymer fuel cell that receives supply of a hydrogen-containing fuel gas and an oxygen-containing oxidizing gas and generates electric power through an electrochemical reaction between the fuel gas and the oxidizing gas. .

  As shown in FIG. 1, the fuel cell 1000 includes a plurality of fuel cells 10 stacked and sandwiched between end plates 85 and 86 from both ends thereof. The end plate 85 includes a through hole 85a for supplying anode gas, a through hole 85b for supplying cathode gas, a through hole 85c for discharging anode off gas, a through hole 85d for discharging cathode off gas, and a through hole 85e for supplying cooling water. A through hole 85f for discharging the cooling water is formed. The anode gas is supplied into the fuel cell 1000 from a fuel gas tank (not shown) through the through hole 85a. The cathode gas is compressed by a compressor (not shown) and supplied into the fuel cell 1000 through the through hole 85b. The cooling water is cooled by a radiator (not shown) and supplied to the fuel cell 1000 through the through hole 85e.

  As shown in FIG. 2, the fuel cell 10 includes an MEA 24 (Membrane Electrode Assembly), gas diffusion layers 23 a and 23 b, gas flow paths 28 and 29, a seal gasket 26, and a separator 40. The gas diffusion layers 23 a and 23 b are disposed on both surfaces of the MEA 24. A member composed of the MEA 24, the gas diffusion layer 23a, and the gas diffusion layer 23b is referred to as MEGA 25. The gas flow paths 28 and 29 are disposed between the MEGA 25 and the separator. The MEGA 25 and the gas flow paths 28 and 29 are formed integrally with the seal gasket 26 so that the outer periphery is surrounded by the seal gasket 26. The separator is disposed on both sides of the MEGA 25, the gas flow paths 28 and 29, and the seal gasket 26 that are integrally formed.

  The MEA 24 includes a cathode electrode catalyst layer 22 a and an anode electrode catalyst layer 22 b on the surface of the electrolyte membrane 21. The electrolyte membrane 21 is a thin film of a solid polymer material that has proton conductivity and exhibits good electrical conductivity in a wet state, and is formed in a rectangle that is smaller than the outer shape of the separator 40 and larger than the outer shape of the gas channel. Yes. The electrolyte membrane 21 is, for example, Nafion. The cathode electrode catalyst layer 22a and the anode electrode catalyst layer 22b formed on the surface of the electrolyte membrane 21 carry a catalyst that promotes an electrochemical reaction, for example, platinum.

  The gas diffusion layers 23a and 23b are carbon porous bodies having a porosity of about 20%, and are formed of, for example, carbon cloth or carbon paper. The gas diffusion layers 23a and 23b are integrated with the MEA 24 by bonding to form the MEGA 25. The gas diffusion layer 23a is disposed on the cathode side of the MEA 24, and the gas diffusion layer 23b is disposed on the anode side. The gas diffusion layer 23a diffuses the cathode gas in the thickness direction and supplies it to the entire surface of the cathode electrode catalyst layer 22a. The gas diffusion layer 23b diffuses the anode gas in the thickness direction and supplies it to the entire surface of the anode electrode catalyst layer 22b. The gas diffusion layers 23a and 23b have a relatively low porosity because the main purpose is gas diffusion in the thickness direction.

  Each of the gas flow paths 28 and 29 is formed by stacking two expanded metals. The expanded metal is a metal plate in which through holes having the same shape are regularly arranged. Each expanded metal is formed of a conductive metal such as stainless steel, titanium, or a titanium alloy. Each expanded metal is formed in a substantially rectangular outer shape slightly smaller than MEGA25. The structure of the expanded metal will be described later. The two expanded metals laminated are joined by diffusion welding, resistance welding, or the like. By joining, the laminated interface of the laminated expanded metal can be decreased, and the generated water generated by the electrochemical reaction can be prevented from entering the laminated interface. Therefore, corrosion of the expanded metal can be suppressed.

  The gas flow path 28 is disposed between the cathode side of the MEGA 25 (cathode side of the MEA 24) and the separator 40, and guides the oxidizing gas supplied via the separator 40 from above to below as shown in FIG. An oxidizing gas is supplied to the cathode side.

  The gas flow path 29 is arranged between the anode side of the MEGA 25 (the anode side of the MEA 24) and the separator 40, and guides the fuel gas supplied via the separator 40 from the upper side to the lower side as shown in FIG. To the anode side.

  The reaction gas flowing through the gas flow paths 28 and 29 is supplied to the MEGA 25 in the course of the flow, and is diffused to the cathode electrode catalyst layer 22a and the anode electrode catalyst layer 22b by the gas diffusion layers 23a and 23b of the MEGA 25, thereby causing an electrochemical reaction. Provided. This electrochemical reaction is an exothermic reaction, and cooling water is supplied into the fuel cell 1000 in order to operate the fuel cell 1000 within a predetermined temperature range.

  The seal gasket 26 is made of an insulating resin material made of rubber, such as silicon rubber, butyl rubber, and fluorine rubber. The seal gasket 26 is injection-molded around the outer periphery of the MEGA 25 and the gas flow paths 28, 29, thereby forming the MEGA 25 and the gas flow paths 28, 29 is integrally formed. As a material of the seal gasket 26, for example, fluororubber is used.

  The seal gasket 26 is formed in a substantially rectangular shape having the same size as the separator 40. As shown in FIG. 1, holes 20 a to 20 f are formed along the four sides of the seal gasket 26. In order to distinguish the manifold holes 20a to 20f provided in the seal gasket 26 and the manifold holes provided in the separator 40, in this embodiment, the holes 20a to 20f of the seal gasket 26 are connected to the communication holes 20a to 20a. Called 20f. Each of the communication holes 20a to 20f of the seal gasket 26 constitutes a part of a manifold of fluid (fuel gas, oxidizing gas, cooling water) inside the fuel cell 1000. The communication hole 20a constitutes a part of the anode gas manifold, and the communication hole 20b constitutes a part of the cathode gas manifold. The communication hole 20c constitutes a part of the anode offgas manifold, the communication hole 20d constitutes a part of the cathode offgas manifold, the communication hole 20e constitutes a part of the cooling water supply manifold, and the communication hole 20f A part of the cooling water discharge manifold.

  The seal gasket 26 is formed with a convex portion 26a surrounding each communication hole in the thickness direction. The convex portion 26a is sandwiched between the separators 40, receives a fastening force in the stacking direction, and is crushed and deformed in the stacking direction. As a result, the convex portion 26a forms a seal line SL that suppresses the leakage of fluid (fuel gas, oxidizing gas, cooling water) from the inside of the manifold, as shown in FIG.

  Next, the separator 40 that collects electricity generated by an electrochemical reaction will be described. The separator 40 is a three-layer laminated separator formed by laminating three metal thin plates. Specifically, the cathode plate 41 that contacts the gas flow path 28 that is the flow path of the oxidizing gas, the anode plate 43 that contacts the gas flow path 29 that is the flow path of the fuel gas, and the sandwiched between both plates The intermediate plate 42 mainly serves as a cooling water flow path.

  The three plates have a flat surface with no irregularities for the flow path in the thickness direction (that is, the contact surfaces with the gas flow paths 28 and 29 are flat), and are made of stainless steel, titanium, or a titanium alloy. For example, it is made of a conductive metal material.

  The three plates are provided with through holes that constitute the various manifolds described above. Specifically, as shown in FIG. 1, an oxidant gas supply through hole 41a and an oxidant gas discharge through hole 41b are provided on the long side of a substantially rectangular separator 40. Further, on the short side of the separator 40, a through hole 41c for supplying fuel gas and a through hole 41d for discharging fuel gas are provided. On the short side of the separator 40, a through hole 41e for supplying cooling water and a through hole 41f for discharging cooling water are respectively provided.

  In addition to the manifold through-holes, the cathode plate 41 is formed with a plurality of holes 45 and 46 that serve as inlets and outlets for the oxidizing gas to the gas flow path 28. Similarly, the anode plate 43 is formed with a plurality of holes (not shown) that serve as inlets and outlets of the fuel gas to the gas flow path 29 in addition to the manifold through holes.

  Of the plurality of manifold through holes provided in the intermediate plate 42, the manifold through hole 42 a through which the oxidizing gas flows is formed so as to communicate with the hole 45 of the cathode plate 41. The manifold through-hole 42b through which the fuel gas flows is formed so as to communicate with a hole (not shown) of the anode plate 43.

  A plurality of notches are formed in the intermediate plate 42 along the long side direction of a substantially rectangular outer shape, and both ends of the notches communicate with manifold through-holes through which cooling water flows.

  By using the separator 40 constituted by laminating such flat plates in combination with gas flow passages 28 and 29 formed by laminating expanded metal, the separator 40 is used for a flow passage by a complicated manufacturing method such as etching. There is no need to form a groove.

  In the present embodiment, hereinafter, the fuel gas and the oxidizing gas are collectively referred to as a reaction gas.

A2. About expanded metal:
The expanded metal which comprises the gas flow paths 28 and 29 is demonstrated using FIGS. Since the first expanded metals 30 and 34 have the same structure, the first expanded metal 30 will be described as an example. Since the second expanded metals 31 and 33 have the same structure, the second expanded metal 31 will be described as an example. Further, the configuration of the gas flow path 28 and the flow of the reaction gas in the gas flow path 28 will be described with reference to FIGS. FIG. 3 is a perspective view illustrating the first expanded metal 30 in the present embodiment. FIG. 4 is a perspective view illustrating the second expanded metal 31 in the present embodiment. FIG. 5 is a schematic diagram for explaining the direction of the major axis of the mesh in the present embodiment. FIG. 6 is an explanatory view for explaining the mesh of the first expanded metal 30 and is a partially enlarged view in which the broken line circle Z in FIG. 3 is enlarged. FIG. 7 is a schematic diagram illustrating the gas flow path 28 in the present embodiment. FIG. 8 is a schematic view illustrating the gas flow in the present embodiment, and is an enlarged view of a circle Y portion in FIG. 2.

  As shown in FIG. 3, the first expanded metal 30 is a metal plate in which a plurality of rhomboid through holes 300 are regularly arranged over a plurality of rows. In the present embodiment, the through hole 300 is hereinafter referred to as a mesh 300. The mesh 300 has a major axis and a minor axis, and is formed so that the direction of the major axis is parallel to the first direction. The first direction in the present embodiment is parallel to the short side of the first expanded metal 30. The horizontal dimension LW1 represents the horizontal dimension of the mesh 300, and the vertical dimension SW1 represents the vertical dimension of the mesh 300. As shown in FIG. 3, the horizontal dimension LW1 = x, the vertical dimension SW1 = y (x> y), and the shape of the mesh 300 is a laterally long rhombus whose major axis is x and minor axis is y. Note that the major axis and the minor axis of the mesh 300 intersect perpendicularly. The first expanded metal 30 is a flat type expanded metal rolled by a skin pass roll.

  Next, the second expanded metal 31 will be described. As shown in FIG. 4, the second expanded metal 31 is a metal plate in which rhombic through holes 310 having the same shape are regularly arranged over a plurality of rows. The through hole 310 has a major axis and a minor axis, and is formed so that the direction of the major axis is parallel to the second direction. The second direction in the present embodiment refers to a direction parallel to the long side of the second expanded metal 31. The second expanded metal 31 is a flat type expanded metal rolled by a skin pass roll in the same manner as the first expanded metal 30. In the present embodiment, the through hole 310 is referred to as a mesh 310, and the second direction is referred to as a mesh arrangement direction of the second expanded metal 31. The mesh 310 has a horizontal dimension LW2 = y and a vertical dimension SW2 = x, and the shape of the mesh 310 is a vertically long rhombus having a major axis x and a minor axis y. Note that the major axis and the minor axis of the mesh 310 intersect perpendicularly.

  As shown in FIG. 5, the arrangement direction of the mesh 310 of the second expanded metal 31 is perpendicular to the arrangement direction of the first expanded metal 30 mesh 300, that is, 90 degrees.

A3. Mesh configuration:
The configuration of the mesh according to the present embodiment will be described with reference to FIG. 6 using the mesh 300 of the first expanded metal 30 as an example. As shown in FIG. 6, the mesh 300 of the first expanded metal 30 includes a strand portion 301, a bond portion 302, and an opening portion 303. The strand portion 301 indicates a portion corresponding to four sides of the mesh 300, and the bond portion 302 indicates a portion where the strand portion 301 intersects. The opening 303 is a penetrating portion formed by the strand portion 301 and the bond portion 302. As described above, the mesh 300 has the horizontal dimension LW1 = x and the vertical dimension SW1 = y (x> y).

  That is, the mesh 300 and the mesh 310 are through holes having the same shape and different arrangement directions by 90 degrees. Since the arrangement directions of the mesh 300 and the mesh 310 are different by 90 degrees, when the first expanded metal 30 and the second expanded metal 31 are laminated, the strand portion 301 of the mesh 300, the strand portion 311 of the mesh 310, and the mesh It can suppress that the bond part 302 of 300 and the bond part of the mesh 310 overlap so that it may correspond.

  Note that the ends of the first expanded metal 30 and the second expanded metal 31 remain in a cut state and are not provided with an outer frame or the like. Moreover, the long diameter of the 1st expanded metal 30 and the 2nd expanded metal 31 is 0.1 mm-0.5 mm.

A4. About gas flow path configuration and power generation performance:
The structure of the gas flow path 28 formed by laminating the first expanded metal 30 and the second expanded metal 31 will be described with reference to FIG. In the schematic diagram 400 of FIG. 7, a plan view of the gas flow path 28 and a cross-sectional view of the gas flow path 28 cut along the BB cross section of the plan view are shown in association with each other. The strand portions and bond portions of mesh 300 and mesh 310 are shown by hatching in schematic diagram 400. In addition, the plan view of the schematic diagram 400 also shows the arrangement direction of the mesh 300 and the mesh 310.

  As shown in the plan view of the schematic diagram 400, in the gas flow path 28 in which the first expanded metal 30 and the second expanded metal 31 are laminated, the mesh 310 of the second expanded metal 31 is the mesh 300 of the first expanded metal 30. In contrast, the arrangement direction differs by 90 degrees.

  Since the arrangement direction of the mesh 300 and the arrangement direction of the mesh 310 are different by 90 degrees, the strand part 301 and the bond part 302 of the first expanded metal 30 and the strand of the second expanded metal 31 are shown in the cross-sectional view of the schematic diagram 400. Overlap with the part 311 and the bond part 312 can be suppressed. Therefore, a reaction gas passageway in which the opening 303 of the first expanded metal 30 and the opening 313 of the second expanded metal 31 communicate with each other is formed in the gas flow path 28.

  The flow of the reaction gas in the gas flow path 28 is shown by a thick line arrow in FIG. In this embodiment, the reaction gas flows in the surface direction (from right to left on the paper surface) and diffuses in the normal direction (from bottom to top on the paper surface). As shown in FIG. 8, the reaction gas supplied from the separator 40 flows in the plane of the opening 303 of the first expanded metal 30 and the opening 313 of the second expanded metal 31, and bonds to the first expanded metal 30. It collides with the part 302 and the strand part 311 of the second expanded metal 31, flows in the normal direction, and diffuses into the MEGA 25. The gas flow path 28 can suppress the formation of partition walls due to the mesh 300 of the first expanded metal 30 and the mesh 310 of the second expanded metal 31 being overlapped and overlapping, and can circulate the reaction gas well in the surface direction.

  The gas flow path formed by shifting the expanded metal having the same shape and the same mesh in the arrangement direction in the vertical and horizontal directions with respect to the gas flow path 28 of the present invention will be described below. The gas flow paths that overlap so that the meshes coincide will be described with reference to FIG. FIG. 9 is a schematic view illustrating a gas flow path 270 formed by stacking two expanded metals having the same mesh shape and arrangement direction. A schematic diagram 410 shows a plan view of the gas flow path 270 and a cross-sectional view of the gas flow path 270 cut along a DD section. Strand portions and bond portions of the first expanded metal 30 and the third expanded metal 35 constituting the gas flow path 270 are indicated by hatching. Further, in the DD cross-sectional view of the schematic diagram 410, the flow of the reaction gas is indicated by a thick arrow.

  In the gas flow path 270, the first expanded metal 30 and the third expanded metal 35 are laminated. The mesh 300 of the first expanded metal 30 and the mesh 350 of the third expanded metal 35 are shifted by about ¼ of the major axis in the arrangement direction of the mesh 300.

  Expanded metal has some errors in the shape and dimensions of the mesh during the manufacturing process. Even if the error is small, the size of the mesh itself is as small as 0.1 mm to 0.5 mm. Therefore, as shown in FIG. 9, the mesh 300 a that is one of the meshes of the first expanded metal 30 and the third expanded The mesh 350a, which is one of the metal 35 meshes, may overlap so as to match. When the mesh 300a and the mesh 350a overlap each other so as to coincide with each other, as shown in the DD cross-sectional view of FIG. 9, the bond portion 302 of the mesh 300a and the bond portion 352 of the mesh 350a overlap to form the partition wall 600. The

  When the partition wall 600 is formed, as shown by thick arrows in FIG. 9, the flow of the reaction gas is inhibited by the partition wall 600, and the flow efficiency of the reaction gas in the surface direction and the diffusion efficiency of the reaction gas into the MEGA are reduced. .

  The power generation performance of the fuel cell 1000 using the gas flow path 28 and the fuel cell using the gas flow path 270 (hereinafter, this fuel cell is referred to as the fuel cell 1000a in this embodiment) will be described with reference to FIG. explain. FIG. 10 is a relationship diagram showing the relationship between the output voltage and the output current of the fuel cell 1000 and the fuel cell 1000a in this embodiment. In the relationship diagram 500, the vertical axis represents the output voltage, and the horizontal axis represents the output current. In the relationship diagram 500, a graph 510 indicated by a solid line indicates the relationship between the output voltage V and the output current I of the fuel cell 1000 using the gas flow path 28 in the present embodiment. A graph 520 shows the relationship between the output voltage and the output current of the fuel cell 1000a using the gas flow path 270 described above.

  As shown in the relationship diagram 500, as the output current I increases, the output voltage of the fuel cell 1000a decreases more quickly than the output voltage of the fuel cell 1000. For example, when the output current is I1, the output voltage V of the fuel cell 1000 is V1, the output voltage V of the fuel cell 1000a is V2, and the fuel cell 1000 can obtain a higher output voltage than the fuel cell 1000a. The reason for this will be described below.

  Expanded metal mesh dimensions vary, so in a gas flow path in which expanded metals with the same mesh shape and arrangement direction are stacked vertically and horizontally, the stacked expanded metal meshes overlap so that they match. The partition walls are likely to be formed by the strand portions and bond portions of each expanded metal. By forming the partition wall, the flow of the reaction gas is hindered, and the flow efficiency of the reaction gas is lowered and the diffusion efficiency of the reaction gas is lowered.

  On the other hand, in the gas flow path 28 of the present invention, since the arrangement directions of the expanded metal meshes stacked are different, the overlapping of the strand portions and the bond portions can be suppressed, and the formation of the partition walls can be suppressed. Therefore, the gas flow path 28 can distribute the reaction gas better than the gas flow path 270 and can efficiently diffuse to the MEGA, so that the concentration overvoltage can be reduced. As a result, the power generation efficiency in the fuel cell 1000 can be improved by about 10% with respect to the fuel cell 1000a.

  According to the fuel cell of the first embodiment described above, since the gas flow path is formed by stacking the expanded metals having different mesh arrangement directions, the adjacent expanded metal strands and bond portions overlap. Can be suppressed. Therefore, it is possible to suppress the formation of partition walls due to the overlap of the strand part and the bond part, and it is possible to improve the distribution efficiency and diffusion efficiency of the reaction gas. Therefore, the power generation efficiency of the fuel cell can be improved.

  Further, according to the fuel cell of the present invention, the expanded metal mesh has a major axis and a minor axis, and the arrangement directions of adjacent expanded metal meshes are different by 90 degrees, so that the meshes overlap each other. The formation of the partition wall can be easily suppressed with high accuracy.

  Moreover, according to the fuel cell of the present invention, since the gas flow path is configured using expanded metal, it can be manufactured easily and inexpensively, and the quality can be controlled.

  Moreover, according to the fuel cell of the present invention, since the gas diffusion layer is provided between the gas flow path and the MEA, the reaction gas flow efficiency in the gas flow path is improved and the diffusion efficiency of the reaction gas to the MEA is improved. It can be improved.

B. Second embodiment:
In the first embodiment described above, two expanded metals are stacked to constitute the gas flow path. In the second embodiment, three expanded metals are stacked to form a gas flow path.

B1. Gas flow path configuration:
The gas flow path in 2nd Example is demonstrated using FIG. FIG. 11 is a schematic cross-sectional view illustrating the configuration of the gas flow path and the flow of the reaction gas in the second embodiment. In the gas flow path 260 of the present embodiment, the fourth expanded metal 32 is disposed between the gas flow path 28 of the first embodiment and the MEGA 25. The fourth expanded metal 32 is the same expanded metal as the first expanded metal 30. That is, the mesh of the fourth expanded metal 32 is 90 degrees different from the mesh 310 of the second expanded metal 31 in the arrangement direction. In the gas flow path 260 composed of three expanded metals, the arrangement directions of the adjacent expanded metal meshes are different, and therefore the formation of the partition walls due to the overlapping of the adjacent expanded metal meshes can be suppressed.

  The flow of the reaction gas is shown in a wave shape by solid arrows in FIG. As shown in FIG. 12, the reactive gas supplied through the separator 40 collides with the strand part and the bond part of each expanded metal while flowing in the surface direction through the openings of each laminated expanded metal. Then, it flows toward the normal direction and diffuses into the MEGA 25.

  Since the gas diffusion efficiency is improved by increasing the number of layers of the expanded metal, the gas flow path 260 of the present embodiment is further diffused than the gas flow path 28 of the first embodiment in which two expanded metals are stacked. Efficiency can be improved. On the other hand, since the fuel cell 1000 increases in size as the number of stacked layers increases, in order to improve gas diffusion efficiency while suppressing the increase in size of the fuel cell 1000, the number of expanded metals constituting the gas flow path is three. preferable.

C. Third Embodiment In the third embodiment, the expanded metal mesh is smaller than the other expanded metal meshes, and the expanded metal is disposed at a position adjacent to the MEGA to form a gas flow path.

C1. Gas flow path configuration:
The gas flow path 261 in the third embodiment will be described with reference to FIG. FIG. 13 is a schematic cross-sectional view illustrating the configuration of the gas flow path and the flow of the reactive gas in the present example. In the gas flow path 261 of the present embodiment, a fifth expanded metal 32a is disposed between the gas flow path 28 of the first embodiment and the MEGA 25. The mesh of the fifth expanded metal 32a has the same arrangement direction as the mesh of the first expanded metal 30, and has a reduced shape of the mesh of the first expanded metal 30.

  The flow of the reaction gas is indicated by a solid line arrow in FIG. As shown in FIG. 13, the reaction gas supplied via the separator 40 collides with the strands and bond portions of each expanded metal while flowing in the plane direction, flows in the normal direction, and is diffused into the MEGA 25. . Since the mesh of the fifth expanded metal 32a is formed smaller than the first expanded metal 30 and the second expanded metal 31, the diffusion of gas to the MEGA 25 is promoted.

  According to the gas flow path 261 of the present embodiment, the size of the mesh of the fifth expanded metal 32a disposed adjacent to the MEGA 25 is smaller than that of the other expanded metal stacked, and is adjacent to the expanded metal mesh. Therefore, the gas distribution efficiency can be improved and the gas diffusion efficiency to MEGA can be improved.

D. Variation:
(1) In the above-described first to third embodiments, the gas flow paths are formed so that the arrangement directions of the adjacent expanded metal meshes are different by 90 degrees. For example, as shown in FIG. The gas flow path may be formed so that the arrangement direction of the expanded metal mesh differs by 45 degrees.

  FIG. 12 is a schematic diagram for explaining the gas flow path 280 in the modified example. In the schematic diagram 450 of FIG. 12, a plan view of the gas flow path 280 and a cross-sectional view of the gas flow path 280 cut along the EE cross section of the plan view are shown in association with each other. In the schematic diagram 450, the first expanded metal 30 and the sixth expanded metal 36 are laminated and formed. The strand portion and the bond portion of the mesh 300 of the first expanded metal 30 and the mesh 360 of the sixth expanded metal 36 are indicated by hatching in a schematic diagram 450.

  An arrangement direction of the mesh 300 and the mesh 360 is also shown in the plan view of the schematic diagram 450. In the gas flow path 280 in which the first expanded metal 30 and the sixth expanded metal 36 are stacked, the mesh 360 of the sixth expanded metal 36 is 45 degrees different from the arrangement direction of the mesh 300 of the first expanded metal 30.

  Since the arrangement direction of the mesh 300 and the arrangement direction of the mesh 360 are different by 45 degrees, as shown in the cross-sectional view of the schematic diagram 450, the bond portion 302 of the first expanded metal 30 and the strand portion 361 of the sixth expanded metal 36 are arranged. There is little overlap. As a result, the opening 303 and the opening 363 are well communicated with each other in the gas flow path 280 to form a gas passage.

  The flow of the reaction gas in the gas flow path 280 is shown by a thick curve arrow in FIG. As shown in FIG. 12, the reaction gas supplied from the separator 40 flows in the surface direction through the opening 303 of the first expanded metal 30 and the opening 363 of the sixth expanded metal 36, and bonds to the first expanded metal 30. It collides with the part 302 and the strand part 361 of the sixth expanded metal 36, flows in the normal direction, and diffuses into the MEGA 25.

  The gas flow path 280 of this modification can suppress the formation of the partition wall 600 due to the overlap of the mesh 300 of the first expanded metal 30 and the mesh 360 of the sixth expanded metal 36, and is the same as the gas flow path 28 of the first embodiment. In addition, the flow efficiency of the reaction gas in the surface direction can be improved, and the diffusion efficiency of the reaction gas in the normal direction can be improved.

  In this modification, the arrangement direction of the mesh 360 is 45 degrees different from that of the mesh 300. However, the present invention is not limited to this. If the arrangement direction of the expanded metal mesh to be laminated is slightly different, the gas diffusion efficiency is improved. it can.

(2) In the first embodiment described above, the expanded metal uses a flat type, but, for example, a standard type expanded metal before rolling may be used.

(3) Moreover, in the above-mentioned Example, although the shape of the expanded metal mesh is a rhombus, it is good also as a tortoiseshell type, for example.

(4) In the first embodiment described above, the gas flow path is formed using the expanded metal. However, for example, a punching metal having a plurality of through holes formed in the metal plate may be used. . In this case, the through hole preferably has a major axis and a minor axis such as an ellipse or a rectangle.

(5) In the first embodiment described above, the expanded metal outer shape is rectangular. However, for example, the expanded metal outer shape may be a square or a circle having no major axis and minor axis. In this case, by preparing multiple expanded metals with the same shape and orientation and stacking them by changing the orientation of the expanded metal itself by 90 degrees, it is possible to simplify gas flow paths with different expanded metal mesh arrangement directions. Can be formed.

(6) In the first to third embodiments described above, the gas flow path is configured by laminating a plurality of expanded metals. For example, a metal plate having through holes of the same shape instead of the expanded metal. May be laminated to form a gas flow path.

(7) In the second embodiment described above, when the three expanded metals are stacked, the first expanded metal 30 and the fourth expanded metal 32 are the same expanded metal, but they may not be the same expanded metal. It is only necessary that the arrangement direction of the mesh of the fourth expanded metal 32 and the arrangement direction of the mesh of the second expanded metal 31 are different. For example, the arrangement direction of the mesh of the fourth expanded metal 32 may be 45 degrees different from the arrangement direction of the mesh of the second expanded metal 31.

  Although various embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to these embodiments and can take various configurations without departing from the spirit of the present invention.

It is explanatory drawing which shows schematic structure of the fuel cell in 1st Example. Sectional drawing of the fuel battery cell in 1st Example. The perspective view which illustrates the expanded metal in 1st Example. The perspective view which illustrates the expanded metal in 1st Example. The schematic diagram explaining the arrangement direction of the mesh in 1st Example. Explanatory drawing explaining the mesh of the expanded metal in 1st Example. The schematic diagram explaining the gas flow path in 1st Example. The schematic diagram explaining the distribution | circulation of the reactive gas in 1st Example. The schematic diagram explaining the gas flow path of the comparative example of the gas flow path in 1st Example. The relationship diagram which shows the relationship between the output current of a fuel cell and output voltage in 1st Example. The cross-sectional schematic diagram explaining the structure of the gas flow path in 2nd Example, and the distribution | circulation of a reactive gas. The cross-sectional schematic diagram explaining the structure of the gas flow path in 3rd Example, and the distribution | circulation of a reactive gas. The cross-sectional schematic diagram explaining the structure of the gas flow path in a modification, and the distribution | circulation of the reactive gas.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 20a-20f ... Communication hole 21 ... Electrolyte membrane 22a ... Cathode electrode catalyst layer 22b ... Anode electrode catalyst layer 23a, 23b ... Gas diffusion layer 26 ... Seal gasket 28, 29 ... Gas flow path 30 ... 1st expand Metal 31 ... 2nd expanded metal 32 ... 4th expanded metal 32a ... 5th expanded metal 35 ... 3rd expanded metal 36 ... 6th expanded metal 40 ... Separator 41 ... Cathode plate 41a-41f ... Through-hole 42 ... Intermediate plate 42a, 42b ... through hole 43 ... anode plate 45 ... hole 85 ... end plate 85a, 85f ... through hole 260 ... gas flow path 261 ... gas flow path 270 ... gas flow path 280 ... gas flow path 300 ... through hole 300 ... mesh 300a ... Mesh 301 ... Stran Part 302 ... Bond part 303 ... Opening part 310 ... Through hole 310 ... Mesh 311 ... Strand part 312 ... Bond part 313 ... Opening part 350 ... Mesh 350a ... Mesh 352 ... Bond part 360 ... Mesh 361 ... Strand part 363 ... Opening part 510 ... Graph 520 ... Graph 600 ... Partition wall 1000 ... Fuel cell 1000a ... Fuel cell

Claims (9)

A fuel cell,
A separator;
A membrane electrode assembly in which catalyst electrode layers are formed on both surfaces of the electrolyte membrane;
First gas channel forming holes having the same shape and disposed between the membrane electrode assembly and the separator and forming a gas channel are regularly arranged in a first direction over a plurality of rows. 1 metal plate,
A second gas flow path forming hole disposed between the membrane electrode assembly and the first metal plate and having the same shape as the first gas flow path forming hole is different from the first direction. And a second metal plate regularly arranged in a plurality of rows in two directions. The fuel cell according to claim 1, wherein
The first gas channel forming hole and the second gas channel forming hole have a major axis and a minor axis,
The major axis of the first gas flow path forming hole is parallel to the first direction,
The fuel cell, wherein a major axis of the second gas flow path forming hole is parallel to the second direction. The fuel cell according to claim 2, wherein
The fuel cell, wherein the first gas flow path forming hole and the second gas flow path forming hole have a rhombus shape.   The fuel cell according to claim 2, wherein the second direction is 90 degrees different from the first direction. The fuel cell according to any one of claims 1 to 4, further comprising:
A third gas flow path forming hole disposed between the second metal plate and the membrane electrode assembly and having the same shape as the second gas flow path forming hole is different from the second direction. A fuel cell comprising a third metal plate regularly arranged in a plurality of rows in three directions. The fuel cell according to any one of claims 1 to 4, further comprising:
The fourth gas flow path forming hole, which is disposed between the second metal plate and the membrane electrode assembly and has a shape in which the second gas flow path forming hole is reduced, is the second direction. A fuel cell comprising a fourth metal plate regularly arranged in a different fourth direction. The fuel cell according to any one of claims 1 to 4, further comprising:
A fuel cell comprising a gas diffusion layer disposed between the membrane electrode assembly and the second metal plate and formed by a conductive porous member. The fuel cell according to any one of claims 1 to 7, further comprising:
The separator is a fuel cell, which is a three-layer stacked separator formed by stacking three conductive plates having conductivity. A fuel cell according to any one of claims 1 to 8,
Each said metal plate is a fuel cell which is an expanded metal.

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