JP4896508B2 - Seal structure between components for fuel cell - Google Patents

Description

  The present invention relates to a seal structure between constituent members for a fuel cell configured by stacking and fastening a large number of constituent members.

  Conventionally, it is composed of a GDL (Gas Diffusion Layer) integrated with an electrolyte membrane made of an ion exchange membrane such as a solid polymer type and a catalyst support layer on which platinum-based catalysts constituting electrodes are supported. Seals between MEA (Mebrane Electrode Assembly), a separator in which a fuel gas containing hydrogen and an oxidizing gas supply groove containing oxygen and an LLC supply groove for cooling reaction heat are formed, and between the MEA and the separators. 2. Description of the Related Art A fuel cell is known in which a unit cell is configured from a gasket, a large number of unit cells are stacked, and the unit cell is configured as a fastening unit.

  As such a sealing structure between constituent members for a fuel cell, there is one described in Patent Document 1 below. Patent Document 1 below discloses that a separator (plate) is provided with a flow path for gas and liquid and a groove for mounting a gasket is provided between the side surface of the gasket and the side wall of the groove. Is provided with a gap of a predetermined size, which is set so as not to prevent the gasket from elastically deforming laterally in the groove when the gasket is compressed during fuel cell assembly. ing. This is because the elastomer material such as rubber used here is excellent in elastic reaction force, so that when the unit cells are stacked and integrated as one piece, the gasket is buried in the groove, and the elasticity of the gasket The measures are taken so that the sealing property is not lost.

Moreover, although it is not a fuel cell, there exists a thing of the following patent document 2 as a seal structure in which the two-step groove | channel was formed in one of the structural members to be sealed. In Patent Document 2 below, when the recessed groove of the intake manifold gasket is formed in two stages and a rubber-like elastic body is provided in the central groove, the rubber-like elastic body compressed when the gasket is tightened However, it is possible to prevent the rubber-like elastic body from being compressed and broken because it can escape to the first step.
JP 2000-249229 A JP-A-8-247292

However, in the sealing structure between the constituent members for fuel cells, the constituent members such as MEA and separator to be sealed are thin and relatively fragile, so that the reaction force received by the gasket is small and the sealing performance is improved. Although an excellent one is desired, the seal structure as described in Patent Document 1 has a problem that damage to the constituent members cannot be ignored because the elastic reaction force of the gasket is large.
In addition, the two-step groove structure described in Patent Document 2 is merely provided with “relief grooves” for preventing compression failure of a rubber-like elastic body that is compressed when tightened.

  By the way, the fuel cell as described above is generally constructed by stacking 100 to 400 unit cells and fastening them together. However, due to the reaction force of the gasket that seals between the constituent members, the constituent members The gap between them is not constant, and a small error for each unit cell becomes a large error of the overall shape of the fuel cell, which makes it difficult to construct a fuel cell having a constant shape and size. Therefore, it is desirable that the constituent members to be laminated are in an infinitely interviewed state (clearance 0).

  The present invention has been made in view of the above circumstances, and the reaction force received by the constituent members by the gasket is small, and between the constituent members of the fuel cell excellent in sealing properties while the constituent members to be stacked are in an interview state. The object is to provide a sealing structure.

The seal structure between the fuel cell constituent members according to the invention of claim 1 is configured by laminating and fastening a plurality of constituent members, and one constituent member to be sealed is for gasket loading. A first groove and a second groove formed along both sides of the first groove, wherein the first groove has a low reaction force gasket in a raised state exceeding the surface position of the one component member. When the other component member to be sealed is united with the one component member to be fastened together, the raised portion of the gasket is compressed and deformed and flows into the second groove, and both components to be sealed The members are in contact with each other , and the gasket is formed by injecting a low-viscosity uncured gasket material into the first groove and forming the raised portion by applying surface tension at the groove edge of the first groove. It is made by curing with And wherein the Rukoto.

In the present invention, as in the invention of claim 2, gasket material consists adhesive viscosity mainly including polyisobutylene 5~10Pa · s, the hardness after curing is JISA35～65 ° Can be. Further, as in the invention of claim 3 , the gasket material can be injected and loaded into the first groove by a dispenser. And like invention of Claim 4 , both the components to be sealed can also be a membrane-electrode assembly and a separator, and like the invention of Claim 5 , the structure of the groove is the first groove. And the weir part lower than the surface position of one component member shall be formed between the 2nd groove | channels. Further, as in the invention of claim 6 , the volume of the second groove can be 100 to 120% of the rising volume of the gasket material.

According to the seal structure between the constituent elements for a fuel cell according to the first aspect of the present invention, since one constituent member to be sealed is provided with the first groove for loading a gasket, a low reaction force gasket is attached to the predetermined member. And a second groove formed along both sides of the first groove, so that when the two components to be sealed are combined and fastened together, the raised portion of the gasket Can be compressed and deformed to flow into the second groove.
Further, since the gasket is sufficiently compressed and deformed even under a low load, the damage to both constituent members to be sealed is small, and the sealing surfaces of the two constituent members can be in an in-contact state (clearance 0). Therefore, even when a large number of component members are stacked, a fuel cell having a uniform shape and size can be formed without causing variations in the gap size between the component members, and a structure with excellent sealing properties. can do.
Further, since the surface of the gasket is raised from the surface position of one component member where the first groove and the second groove are formed, the surface of the other component member to be sealed need not be processed. The sealing property is ensured by the elastic deformation of the raised portion, and it can be applied flat.

Further, the gasket may be injected uncured gasket material of the low viscosity first groove, and the surface tension at the groove edge portion of the first groove to form a raised portion is formed by curing in this state it can. Therefore, even if the viscosity is low, the raised portion of the gasket can be easily formed by the surface tension of the groove edge portion of the first groove. Further, because of the low viscosity, uneven portions that tend to occur in the rising portion of the gasket and, for example, the start portion and the stop portion when applied by a dispenser are smoothed, and a seal top having a uniform height can be formed. Furthermore, the gasket can be directly formed on the constituent member without an adhesive without requiring a molding die for molding the gasket or a complicated seal design, and the manufacturing cost can be reduced.

According to the seal structure between the constituent members for a fuel cell according to the invention of claim 2 , the gasket material is made of an adhesive mainly composed of polyisobutylene having a viscosity of 5 to 10 Pa · s, and the hardness after curing is JIS A35. It can be ˜65 °.
In addition, since the gasket material is mainly composed of polyisobutylene as described above, if it is cured, the gasket material can be used as a gasket for sealing between the components for the fuel cell. Acid resistance, heat resistance, moisture resistance, gas barrier properties It can be made excellent. Therefore, high sealing performance can be maintained even in a harsh environment during operation of the fuel cell. Furthermore, since the gasket is made of an adhesive having polyisobutylene as a main material, it adheres well to the components to be sealed, and can be made to have a higher sealing performance while having a low reaction force. Since the gasket adheres to the first groove and the second groove without an adhesive, the process of applying the adhesive is eliminated, and the manufacturing becomes easy.

  When the viscosity is less than 5 Pa · s, the surface tension does not rise at the groove edge portion of the first groove, and it flows laterally to the second groove and the sealing performance cannot be maintained. In addition, the curing time tends to be long. Furthermore, physical properties are lowered (such as compression set) and the sealing properties tend to be poor, such as poor adhesion to the constituent members to be sealed. Moreover, when the said viscosity is larger than 10 Pa * s, a viscosity is too high and the handleability at the time of filling a 1st groove | channel will worsen. In particular, it becomes difficult to inject with, for example, a dispenser. In addition, it is difficult to form irregularities that tend to occur at the rising portion of the gasket injected into the first groove and at the start and stop portions when applied by, for example, a dispenser, and it is difficult to form a seal top having a uniform height. .

  When the hardness after the gasket material is cured is less than JIS A35 °, the reaction force becomes too small and the sealing performance is deteriorated. Further, when the hardness is greater than JIS A 65 °, the swelled portion of the gasket is not easily compressed and deformed, and both constituent members to be sealed cannot be brought into an in-contact state (clearance 0). In addition, the reaction force increases and damages the structural member to be sealed.

According to the seal structure between the constituent elements for a fuel cell according to the invention of claim 3 , the gasket material can be injected and loaded into the first groove by a dispenser.
Therefore, since a gasket can be formed only by heat-curing in an oven, for example, without requiring a molding device for molding the gasket, the manufacturing process can be greatly reduced, and low cost can be realized.

According to the seal structure between the constituent members for a fuel cell according to the invention of claim 4 , both constituent members to be sealed can be a membrane-electrode assembly and a separator, both of which are relatively weak. It is possible to realize a low reaction force seal structure that causes little damage to the member.

According to the seal structure between the constituent members for a fuel cell according to the fifth aspect of the present invention, the weir portion lower than the surface position of one constituent member is formed between the first groove and the second groove. The first groove can be deeply secured within the limited thickness of the constituent members.

According to the seal structure between the constituent members for a fuel cell according to the invention of claim 6 , the volume of the second groove can be 100 to 120% of the rising volume of the gasket material. Therefore, even when the gasket is pushed out by gas pressure, LLC water pressure, etc. during the operation of the fuel cell, it is possible to maintain the contact state (clearance 0) between the components to be sealed, which is high. Sealing performance can be demonstrated.
When the volume of the second groove is made smaller than 100% of the rising volume of the gasket material, the gasket protrudes from the surface position of the constituent member, and there is a tendency that the contact state (clearance 0) cannot be achieved.
In addition, when the volume of the second groove is larger than 120% of the rising volume of the gasket material, the space portion generated between the gasket and the second groove which is compressed and deformed and flows into the second groove is too much, The gasket easily moves during the operation of the fuel cell, resulting in poor sealing performance.

  The best mode for carrying out the present invention will be described below with reference to the drawings. 1 is an exploded partial cross-sectional view of a fuel cell component in which the seal structure of the present invention is adopted, FIG. 2 is an enlarged view of a portion X in FIG. 1, and FIGS. 3 and 4 are the same as FIG. 2 of another embodiment. FIG. Here, FIG. 1 shows a state before the constituent members for fuel composition are fastened by layer stacking.

  As shown in FIG. 1, the fuel cell main body (stack) is laminated via an electrolyte membrane made of an ion exchange membrane such as a solid polymer type and a catalyst carrying layer on which platinum catalyst constituting an electrode is carried on both sides thereof. One unit cell is constituted by the MEA 3 made of the integrated GDL and the separators 1 and 2 sandwiching the MEA 3, and a plurality of unit cells are stacked and fastened.

On the side of the separators 1 and 2 facing the MEA 3, a fuel gas flow path 1 a and an oxidizing gas flow path 2 a are formed by a concave groove. In this fuel cell, a pair of electrodes (anode and cathode) are arranged with the MEA 3 in between, and the fuel gas is supplied to the anode electrode through the fuel gas passage 1a and to the cathode electrode through the oxidizing gas passage 2a. In addition, an oxidizing gas is supplied, and energy generated by using a chemical reaction occurring at both electrodes is obtained as electric power.
Hydrogen used as a fuel gas for fuel cells is a colorless, odorless flammable gas that has a low molecular weight so that it does not leak through a small gap. Also, when fuel gas and oxidizing gas are mixed, the power generation efficiency decreases. A gasket 4 is integrally formed at predetermined portions 1 and 2.

The separator 1 which is one constituent member to be sealed includes a first groove 11 for loading a gasket and second grooves 12 formed along both sides of the first groove 11. In FIG. 2 (FIG. 2A), the second groove 12 is formed shallower than the first groove 11. The gasket 4 is injected and loaded into the first groove 11 by a dispenser D attached to a robot or the like with a low-viscosity and uncured gasket material, and the surface tension at the groove edge 11a of the first groove 11 is applied. A raised part is formed.
The gasket material loaded in the first groove 11 is loaded to a raised state exceeding the surface position L shown in FIG. When the MEA 3 is united with the separator 1 in the direction of the white arrow in FIG. 2B to be fastened and integrated, the raised portion is compressed and deformed into the second groove 12 as shown in FIG. At the same time, the MEA 3 and the separator 1 are brought into an interview state (clearance 0).

Here, if the volume of the second groove 12 is 100 to 120% of the rising volume of the gasket material, the gasket 4 is pushed out by gas pressure, LLC water pressure, etc. during the operation of the fuel cell. Even in this case, it is possible to maintain the contact state (clearance 0) between the constituent members to be sealed, and to exhibit high sealing performance.
2A and 2B show an example in which the volume of the second groove 12 is formed to be 100% of the rising volume of the gasket material. With this configuration, when the MEA 3 and the separator 1 are layered, the gasket 4 that has flowed into the second groove 12 does not protrude from the surface position of the separator 1, and the MEA 3 and the separator 1 are in a face-to-face state. (Clearance 0).
FIGS. 3A and 3B show an example in which the volume of the second groove 12 is 120% of the rising volume of the gasket material. Thus, if the volume is limited to 120%, the space generated between the gasket 4 and the second groove 12 which is compressed and deformed and flows into the second groove 12 when the MEA 3 and the separator 1 are layered and fastened. The portion C can maintain the sealing performance without affecting the sealing performance even if the gasket 4 moves somewhat during the operation of the fuel cell.

According to the seal structure of the present invention, since the gasket 4 has a low reaction force and the second groove 12 is provided as a crushing margin of the gasket 4, the MEA 3 and the separator 1 are fastened with a clearance of 0. Since they can be integrated, the gap between the MEA 3 and the separator 1 becomes zero as a whole fuel cell, and the design error in the overall shape in which a large number of layers are stacked is reduced. Further, according to the seal structure of the present invention, when stacking unit cells and fastening the stack, the gasket 4 is compressed and deformed between the MEA 3 and the separator 1 to the two-dot chain line position L in FIG. The seal is maintained by the restoring elasticity, and the gasket 4 is appropriately adhered to the MEA 3 or the separators 1 and 2, so that the sealing performance can be further improved. Further, since the gasket 4 is sticky, it can be loaded and cured by applying it to the first groove 11 with the dispenser D, and can be firmly bonded to the separators 1 and 2 without applying an adhesive. It can be integrally formed.
The method of curing the gasket material is not limited to heat curing, room temperature curing, etc., but the method of room temperature curing after removing the air contained in the gasket material at the time of loading is simple and cost-effective. It is valid.

The gasket material loaded in the first groove 11 is preferably made of an adhesive mainly composed of polyisobutylene having a viscosity of 5 to 10 Pa · s, and has a hardness after curing of JISA 35 to 65 °.
This is because according to this, it is easy to carry out injection loading by the dispenser D or the like, and even after loading, an ideal raised portion can be formed by the surface tension at the groove edge portion 11a of the first groove 11. It is.
Here, the filler to be filled in polyisobutylene is not particularly limited, but for example, titanium oxide, carbon, silica, clay, calcium carbonate, barium sulfate, diatomaceous earth, alumina, lexi charcoal, zeolite, etc. are generally used. A filler can be used. In addition to the filler, as an additive blended with polyisobutylene as a main material, a curing agent, a catalyst, an antiaging agent, and the like are appropriately added.

Here, the GDL constituting the MEA 3 is made of a sheet of carbon fiber or metal fiber, and the side facing the electrolyte membrane is a catalyst supporting layer supporting a platinum-based catalyst. The catalyst support layer on the gas diffusion side is the oxygen electrode (cathode), and the catalyst support layer on the fuel gas diffusion side is the fuel electrode (anode). The electrolyte membrane is made of a solid polymer ion exchange membrane and has a thickness of about 25 μm, but is not limited thereto.
The separators 1 and 2 are not limited to metal plates such as stainless steel, but may be made of conductive resin, or carbon plates formed by mixing carbon powder and synthetic resin.

In the example shown in FIGS. 4A and 4B, a dam portion 13 having a height lower than the surface position of the separator 1 is formed between the first groove 11 and the second groove 12. It is characterized by. In the configuration and effect of the present embodiment, the same reference numerals are given to the portions common to the first embodiment, and the description of the common portions is omitted.
In this embodiment, when the MEA 3 to be sealed and the separator 1 are fastened together in the direction of the white arrow shown in FIG. 3 (b), the gasket 4 is compressed and deformed, gets over the weir 13 and into the second groove. At the same time, the MEA 3 and the separator 1 are brought into an interview state (clearance 0).

  Needless to say, the overall shape and the like of the constituent members for a fuel cell in which the seal structure of the present invention is used are not limited to those shown in the drawings. In the illustrated example, the seal structure between the MEA and the separator has been described. However, it goes without saying that the present invention can also be applied to a seal structure between a separator and a separator as a sealing target of a component for a fuel cell. Yes. Furthermore, the second groove may be formed along the first groove, and the shape and configuration of the groove are not limited to the illustrated example, and the second groove is formed on both sides of the first groove. It is not limited to what is formed, and may be formed only on one side (one side) of the first groove. And a 1st groove | channel and a 2nd groove | channel may be provided in MEA.

1 is an exploded partial cross-sectional view of a fuel cell component in which a seal structure of the present invention is employed. It is an enlarged view of the X section in FIG. It is a figure similar to FIG. 2 of another embodiment. It is a figure similar to FIG. 2 of another embodiment.

Explanation of symbols

1, 2 Separator 11 First groove 11a Groove edge 12 Second groove 13 Weir 3 MEA
4 Gasket C Space part D Dispenser L Surface position

Claims (6)

A seal structure between constituent members for a fuel cell configured by stacking and fastening a large number of constituent members,
One component to be sealed includes a first groove for gasket loading and a second groove formed along both sides of the first groove, and a low reaction force gasket is provided in the first groove. When it is loaded in a raised state exceeding the surface position of one constituent member and the other constituent member to be sealed is combined with this one constituent member and fastened together, the raised portion of the gasket is compressed and deformed, and While flowing into the two grooves, both components to be sealed are brought into an interview state with each other,
The gasket is formed by injecting a low-viscosity uncured gasket material into the first groove, forming a bulge portion by applying surface tension at the groove edge of the first groove, and curing in this state. There is provided a sealing structure between constituent members for a fuel cell.   The seal structure between the constituent members for a fuel cell according to claim 1,
  The gasket material is made of an adhesive mainly composed of polyisobutylene having a viscosity of 5 to 10 Pa · s, and has a hardness after curing of JIS A of 35 to 65 °. Seal structure.   In the seal structure between the constituent members for a fuel cell according to claim 1 or 2,
  The gasket structure is a sealing structure between constituent members for a fuel cell, wherein the gasket material is injected and loaded into the first groove by a dispenser.   In the seal structure between the constituent members for a fuel cell according to any one of claims 1 to 3,
  A sealing structure between constituent members for a fuel cell, wherein both constituent members to be sealed are a membrane-electrode assembly and a separator.   In the seal structure between the structural members for a fuel cell according to any one of claims 1 to 4,
  A sealing structure between constituent members for a fuel cell, wherein a weir portion having a height lower than the surface position of one constituent member is formed between the first groove and the second groove.   In the seal structure between the structural members for a fuel cell according to any one of claims 1 to 5,
  The volume structure of the second groove is 100 to 120% of the rising volume of the gasket material.

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