JP2009176621A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of restraining air from accumulating in a space between a double seal. <P>SOLUTION: A partition 70 is arranged between an outer seal 51 and an inner seal 52 for double-sealing between separators 22A, 22B, and is so made to release air in a space 80 between the outer seal 51 and the inner seal 52. It is preferable that the outer seal 51 and the inner seal 52 are made of a hardened liquid adhesive. It is preferable that the partition 70 is formed by two partitioned sections 71, 72 in order to escape the air, and is preferably made of a resin or a metal material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell in which laminated components are double-sealed.

  Conventionally, as a polymer electrolyte fuel cell, for example, one described in Patent Document 1 is known. A single cell of this fuel cell is composed of a membrane-electrode assembly (MEA) consisting of an electrolyte membrane and a pair of electrodes that sandwich the electrolyte membrane, and a pair of separators that sandwich the MEA. As another unit cell, one in which a separator sandwiches the MEA via a resin frame is also known. Further, in general, a fuel cell stack is configured by stacking a plurality of single cells and applying a predetermined compressive load in the stacking direction.

  The fuel cell components must be hermetically sealed so that the oxidizing gas, the fuel gas, and the cooling water are not mixed. The seal structure of Patent Document 1 seals between the electrolyte membrane and the separator with two seal members. The space between the seal members is configured as a water vapor flow path so that the amount of humidification of the electrolyte membrane can be controlled. However, Patent Document 1 does not disclose any kind of seal member.

As the sealing member, in general, a solid gasket or a liquid adhesive solidified in advance is known. For example, in a single cell without a resin frame, an adhesive is filled between a pair of separators, and sealing is performed by bonding between these. In this case, the adhesive also serves as a spacer in addition to the purpose of sealing.
JP 2002-198070 A

  However, in the double seal structure as in Patent Document 1, when an adhesive is used as the seal member, the size of the adhesive is determined depending on the course, and therefore air may be caught between the seal members. If heat is applied to cure the adhesive in this state, the adhesive may be cut off due to thermal expansion of the air, and the sealing performance may be reduced.

  Accordingly, an object of the present invention is to provide a fuel cell capable of suppressing air from accumulating in a space between double seals.

  In order to achieve the above object, a fuel cell according to the present invention comprises a plurality of components laminated, and at least some of the components are double sealed with a seal structure. The structure has a first seal part and a second seal part inside the first seal part, and there is a partition between the first seal part and the second seal part, A partition is comprised so that the air in the space between the 1st seal part and the 2nd seal part may escape outside the space.

  According to this configuration, the air in the space that is double-sealed by the first and second seal portions can escape from the space by the partition. Thereby, it is possible to suppress the accumulation of air in the space, and it is possible to suppress damage to the seal portion due to the expansion of the air in the space.

  Here, the first seal portion and the second seal portion are preferably those obtained by curing the adhesive, and the present invention is particularly suitable when heat is applied to cure the adhesive. According to the present invention, since there is a partition as described above, it is easy to accurately apply the adhesive to a predetermined position, and it is not necessary to collect air between the double seals of the adhesive after application.

  More preferably, the partition may have two partition portions so that air in the space flows between the two partition portions and escapes out of the space. By doing so, the air in the space can be released to the outside with a simple structure.

  More preferably, the two partition parts have a substantially triangular cross section. By doing so, the distance between the two partition portions can be shortened as much as possible, and a relatively large space for the adhesive can be taken.

  More preferably, the partition may be formed of the same material as at least one of the two components sealed by the seal structure.

  Preferably, the plurality of components include a membrane-electrode assembly and a pair of separators sandwiching the membrane-electrode assembly, and the seal structure is between the membrane-electrode assembly and the separator or a pair of separators. A double seal between the separators is recommended.

  Preferably, the fuel cell is formed by laminating a plurality of single cells each including a membrane-electrode assembly and a pair of separators sandwiching the membrane-electrode assembly, and the sealing structure includes the separator of one adjacent single cell and the other. It is good to double seal between the single cell separator.

  According to the fuel cell of the present invention, it is possible to suppress the accumulation of air in the space between the double seals and to ensure the sealing performance.

  Hereinafter, a fuel cell according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. Here, a solid polymer fuel cell suitable for a vehicle will be described as an example. This type of fuel cell is suitable for a vehicle, but is not limited thereto, and can be mounted on a self-propelled moving body such as a ship, an airplane, and a robot, or can be used as a stationary power source. It is.

  As shown in FIGS. 1 and 2, a fuel cell 1 having a stack structure has a cell stack 3 formed by stacking a plurality of single cells 2 as basic units, and the cell stack 3 has a predetermined structure in the stacking direction. Compressive load is applied. Current collector plates 5a and 5b, insulating plates 6a and 6b, and end plates 7a and 7b are sequentially arranged outside the single cell 2 positioned at both ends of the cell stack 3 respectively. The tension plates 8 and 8 are bridged between the end plates 7a and 7b, fixed to these by bolts 9, and the stacked state of the cell stack 3 and the like is constrained. An elastic module 10 is provided between the end plate 7b and the insulating plate 6b to hold the plurality of elastic bodies 12 with a pair of plates 11 and 11, and the adjustment screw 13 applies a compressive load to the cell stack 3. It can be adjusted.

  The fuel gas, the oxidizing gas, and the refrigerant are supplied to the manifold 20a in the cell stack 3 from the supply pipe 18 connected to the supply ports 15a, 16a, and 17a of the end plate 7a. Thereafter, the fuel gas, the oxidizing gas, and the refrigerant flow in the planar direction of the single cell 2 while flowing through the manifold 20a extending in the cell stacking direction. Finally, the fuel gas, the oxidizing gas, and the refrigerant flow from the manifold 20b in the cell stack 3 to the discharge pipe 19 connected to the discharge ports 15b, 16b, and 17b of the end plate 7, and are discharged out of the fuel cell 1. Is done.

  The supply pipe 18, the discharge pipe 19, and the manifolds 20a and 20b are provided corresponding to the fluids of the fuel gas, the oxidizing gas, and the refrigerant. However, in FIG. Yes. Further, the fuel gas is a hydrogen gas containing hydrogen, and the oxidizing gas is a gas containing an oxidant represented by oxygen or air. The fuel gas and the oxidizing gas may be collectively referred to as a reaction gas. The refrigerant is, for example, cooling water.

  As shown in FIG. 3, the single cell 2 includes an MEA 20 (membrane-electrode assembly) and a pair of separators 22A and 22B.

  The MEA 20 includes an electrolyte membrane 30 made of an ion exchange membrane and a pair of electrodes 32A and 32B sandwiching the electrolyte membrane 30. The electrodes 32A and 32B are obtained by binding a catalyst layer made of, for example, platinum to a diffusion layer made of, for example, a porous carbon material. The diffusion layer of the electrode 32A faces the fuel gas flow path 40 of the separator 22A, and has a function of allowing the fuel gas to pass therethrough and a function of electrically connecting the catalyst layer and the separator 22A. On the other hand, the diffusion layer of the electrode 32B faces the oxidizing gas flow path 42 of the separator 22B, and has a function of allowing the oxidizing gas to pass therethrough and a function of electrically connecting the catalyst layer and the separator 22B.

  When the fuel gas channel 40 supplies fuel gas to the electrode 32A and the oxidizing gas channel 42 supplies oxidizing gas to the electrode 32B, an electrochemical reaction occurs in the MEA 20 and an electromotive force is obtained. In addition, this electrochemical reaction generates water and generates heat on the electrode 32B side. And since a refrigerant | coolant flows into a refrigerant | coolant flow path (44A, 44B), the heat | fever of the single cell 2 is reduced and the operating temperature of the fuel cell 1 is maintained in the predetermined | prescribed range. The refrigerant flow path is configured by communication between the refrigerant flow path 44A on the back surface of the separator 22A and the refrigerant flow path 44B on the back surface of the separator 22B.

  The separators 22A and 22B are made of a gas impermeable conductive material. Examples of the conductive material include carbon, a hard resin having conductivity, and metals such as aluminum and stainless steel. In the present embodiment, the separators 22A and 22B are made of carbon and are formed in a rectangular shape in plan view. Separator 22A, 22B has the non-electric power generation area | region where the electric power generation of the single cell 2 is not carried out in an outer peripheral part. Although not shown in the non-power generation region, each inlet manifold (a part of the manifold 20a) and each outlet manifold (a part of the manifold 20b) of the fuel gas, the oxidizing gas, and the refrigerant are formed to penetrate therethrough. Then, a double seal structure 50 shown in FIG. 4 is provided in this non-power generation region.

  The double seal structure 50 is at least between the constituent members constituting the single cell 2 of the fuel cell 1, for example, at least between the MEA 20 and the separator 22A, between the MEA 20 and the separator 22B, and between the separator 22A and the separator 22B. One can be provided. When provided between the MEA 20 and the separator 22A or the separator 22B, a double seal structure is provided between the electrolyte membrane 30 or the electrode 32A and the separator 22A, and between the electrolyte membrane 30 or the electrode 32B and the separator 22B. 50 can be provided.

  Further, the double seal structure 50 is provided between the constituent members constituting the fuel cell 1, for example, between the single cell 2 and the single cell 2 (that is, the separator 22A of one single cell 2 and the separator of the other single cell 2). 22B), between the single cell 2 serving as a so-called end cell and the current collector plate 5a, and at least one between the single cell 2 serving as a so-called end cell and the current collector plate 5b. Hereinafter, an example in which the double seal structure 50 is provided between the separator 22A and the separator 22B in the single cell 2 will be described.

  As shown in FIG. 4A, the double seal structure 50 includes an outer seal portion 51 (first seal portion) and an inner seal portion 52 (second seal portion). The outer seal portion 51 and the inner seal portion 52 are formed by curing a liquid adhesive, and are formed in a square cross section, for example. The outer seal portion 51 is formed by being filled with more adhesive than the inner seal portion 52, and is located outside the inner seal portion 52 on the inner plane (plane perpendicular to the cell stacking direction) of the fuel cell 1. Is located. As an example, the outer side surface 53 of the outer seal portion 51 is on the outer peripheral side of the single cell 2, and the inner side surface 54 of the inner seal portion 52 is on the MEA 20 side. In addition, the adhesive agent used for the outer side seal part 51 and the inner side seal part 52 may mutually differ, and may be the same.

  Separator 22A and separator 22B have application surfaces 61A and 61B on surfaces facing each other. The application surfaces 61A and 61B are formed in steps so that the distance between the application surfaces 61A and 61B is greater on the outer side than on the inner side. For this reason, the adhesion thickness of the outer seal part 51 is thicker than the adhesion thickness of the inner seal part 52. The total width W1 of the application surfaces 61A and 61B is, for example, 5 mm, and the present invention is suitable for a wide application range where the total width W1 exceeds 5 mm.

  The partition 70 is provided between the outer seal portion 51 and the inner seal portion 52. The partition 70 includes two partition parts 71 and 72 and is formed of a resin or a metal material. The partition 70 can be formed of the same material as the base, that is, the separator 22A here. Although the partition 70 may be configured separately from the separator 22A, it is desirable to fix the partition 70 to the separator 22A with an adhesive different from the double seal structure 50. Therefore, the cost can be reduced and the workability can be improved if the partition 70 is configured integrally with the separator 22A.

  The partition parts 71 and 72 extend in parallel and both have the same cross-sectional shape. The cross-sectional shape of the partition parts 71 and 72 is preferably a shape that allows the partition parts 71 and 72 to approach each other, and is substantially triangular here. For this reason, a substantially inverted triangular gap is formed between the partition parts 71 and 72. Moreover, the vertex of the partition parts 71 and 72 is not in contact with the application surface 61B of the separator 22B. In this way, by adopting a structure in which the flat portions are not provided at the apexes of the partition portions 71 and 72, the distance W2 between the partition portions 71 and 72 can be increased as compared with the structure having the flat portions as shown in FIG. Since it can be made as short as possible, the space for the adhesive of the double seal structure 50 can be widened in the total width W1 of the application range. The “substantially triangular” of the partition parts 71 and 72 includes a triangle with an R (arc) at the apex of the triangle on the separator 22B side.

  The partition 70 is configured such that air in the space 80 between the outer seal portion 51 and the inner seal portion 52 can flow outside the space 80 by flowing through a substantially inverted triangular gap between the partition portions 71 and 72. Has been. An example of this is shown in FIG. 4B. Air in the space 80 flows toward the intersection 86 as indicated by an arrow 84, and flows toward the MEA 20 from the intersection 86 as indicated by an arrow 88. The space 80 is pulled out. As shown in FIG. 4B, the inner seal portion 52 is composed of two seal sections 52a and 52b, and air from the intersecting portion 86 is sealed by the partition 90 having the same structure as the partition 70. It flows through the space between them.

  The operational effects of the present embodiment described above will be described. First, the seal structure according to the comparative example will be described with reference to FIGS.

  As shown in FIG. 6A, when the adhesive 100 is applied to the center of the total width W1 of the application range in order to provide a single seal between the separators 22A and 22B, as shown in FIG. 100 may protrude beyond the coating range. Further, as shown in FIG. 6B, there is a possibility that the adhesive 100 cannot be sufficiently filled in the application range, or the air is bitten by the difference in the application surfaces 61A and 61B. As described above, with the single seal, it is difficult to accurately apply the adhesive 100 in a necessary range, and there is a possibility that the sealing performance cannot be secured due to the expansion of the entrained air. In particular, in the seal structure with the adhesive 100, the adhesive 100 functions as a spacer. Therefore, if there is an unfilled portion, the separators 22 </ b> A and 22 </ b> B may be deformed by the stack fastening load (compression load) of the fuel cell 1. There is.

  As shown in FIG. 7A, in order to double-seal between the separators 22A and 22B, adhesives 110 and 112 are applied to the inside and the outside of the total width W1 of the application range, respectively. As shown in FIG. 5, a portion where air accumulates in the space between the adhesives 110 and 112 may occur. If heat is applied to cure the adhesives 110 and 112 in this state, there is a possibility that the coating line by the adhesives 110 and 112 may be cut off due to the thermal expansion of air, as shown in FIG.

  In contrast to such a comparative example, according to the present embodiment, since there is a partition 70, it is easy to accurately apply an adhesive at a predetermined position for double sealing. Moreover, since the air in the space 80 between the outer seal portion 51 and the inner seal portion 52 can be released to the outside by the partition 70, it is possible to suppress the accumulation of air in the space 80. Thereby, even if it heats for hardening after application | coating of an adhesive agent, damage to the outer side seal part 51 and the inner side seal part 52 can be suppressed, and a sealing performance can be ensured.

  In addition, as the double seal structure 50 of this embodiment, both the outer seal portion 51 and the inner seal portion 52 are made of an adhesive, but this embodiment is also applied to one or both of which are made of a solid gasket in advance. Is possible.

1 is a perspective view of a fuel cell according to an embodiment. It is sectional drawing which shows a part of fuel cell which concerns on embodiment in cross section. It is sectional drawing which shows a part of cell laminated body of the fuel cell which concerns on embodiment. It is a figure which shows the double seal structure of the fuel cell which concerns on embodiment, (a) is sectional drawing, (b) is the top view of (a) which abbreviate | omits and shows the separator 22B. It is sectional drawing which shows the double seal structure of the fuel cell which concerns on a comparative example. It is a figure which shows the seal structure of the fuel cell which concerns on another comparative example, (a) is sectional drawing before sealing, (b) is sectional drawing after sealing. It is a figure which shows the double seal structure of the fuel cell which concerns on another comparative example, (a) is sectional drawing before sealing, (b) is sectional drawing after sealing, (c) omits separator 22B. It is a top view of (b) shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Single cell, 20 ... MEA (membrane-electrode assembly), 22A ... Separator, 22B ... Separator, 50 ... Seal structure, 51 ... Outer seal part (first seal part), 52 ... Inside Seal part (second seal part), 70 ... partition, 71, 72 ... partition part, 80 ... space

Claims (7)

A fuel cell in which a plurality of components are laminated, and at least some of the components are double sealed with a seal structure,
The seal structure includes a first seal portion and a second seal portion located inside the first seal portion,
There is a partition between the first seal part and the second seal part,
The partition is configured to release air in a space between the first seal portion and the second seal portion to the outside of the space.   The fuel cell according to claim 1, wherein the first seal part and the second seal part are formed by curing an adhesive.   The fuel cell according to claim 2, wherein the partition has two partition parts, and air in the space flows between the two partition parts and escapes from the space.   The fuel cell according to claim 3, wherein the two partition parts have a substantially triangular cross section.   The fuel cell according to any one of claims 2 to 4, wherein the partition is formed of the same material as at least one of two components to be sealed by the seal structure. The plurality of components include a membrane-electrode assembly and a pair of separators that sandwich the membrane-electrode assembly,
The fuel cell according to any one of claims 2 to 5, wherein the seal structure double seals between the membrane-electrode assembly and the separator or between the pair of separators. The fuel cell is formed by laminating a plurality of single cells including a membrane-electrode assembly and a pair of separators sandwiching the membrane-electrode assembly.
6. The fuel cell according to claim 2, wherein the seal structure double seals between a separator of one adjacent single cell and a separator of the other single cell. 7.

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