阅读说明：本技术 燃料电池单元用隔板的密封结构 (Sealing structure of separator for fuel cell ) 是由 松田泰辅 渡部茂 于 2020-08-24 设计创作，主要内容包括：本发明得到一种密封结构,其不产生大的紧固力就能够追随一对燃料电池单元用隔板之间的间隙的变动。夹着作为对象构件的电解质膜而面对的一对隔板(11、11A、11B)具有与电解质膜紧密接触而在与该电解质膜之间形成流体的流路的凸筋(14、14A、14B)。密封一对隔板(11、11A、11B)的密封部件使该一对隔板11(11A、11B)的凸筋(14、14A、14B)呈嵌套状地重合,并在相互面对的凸筋(14、14A、14B)彼此的侧壁(15、15A、15B)之间设有具有弹性的密封件(203)。在一对隔板(11、11A、11B)之间的间隙变动时,密封件(203)沿剪切方向变形。(The invention provides a seal structure which can follow the change of a gap between a pair of fuel cell separators without generating large fastening force. A pair of separators (11, 11A, 11B) facing each other with an electrolyte membrane as a target member interposed therebetween has ribs (14, 14A, 14B) that are in close contact with the electrolyte membrane and form a fluid flow path between the separators and the electrolyte membrane. A sealing member for sealing a pair of separators (11, 11A, 11B) is configured such that ribs (14, 14A, 14B) of the pair of separators (11A, 11B) are overlapped in a nested manner, and a seal (203) having elasticity is provided between side walls (15, 15A, 15B) of the mutually facing ribs (14, 14A, 14B). When the gap between the pair of separators (11, 11A, 11B) fluctuates, the seal (203) deforms in the shearing direction.)

1. A seal structure of a separator for a fuel cell unit, comprising:

a pair of partition plates facing each other with an object member interposed therebetween and having a rib that is in close contact with the object member to form a fluid flow path between the pair of partition plates and the object member; and

and a seal member in which the ribs of the pair of separators are overlapped in a nested manner, and a seal member having elasticity is provided between side walls of the ribs facing each other.

2. The sealing structure of a separator for a fuel cell unit according to claim 1,

the side walls of the ribs facing each other of the pair of partitions rise from the partitions at an angle of 5 to 90 degrees.

3. The sealing structure of a separator for a fuel cell unit according to claim 2,

the side walls of the ribs of the pair of partitions facing each other are inclined with respect to the partitions.

4. The seal structure of a separator for a fuel cell unit according to any one of claims 1 to 3,

the seal member has adhesiveness to the side wall of the rib.

5. The sealing structure of a separator for a fuel cell unit according to claim 4,

the sealing member is a rubber molded product having adhesiveness.

6. The sealing structure of a separator for a fuel cell unit according to claim 4,

the seal member has an adhesive layer at a contact portion with respect to the side wall of the bead.

7. The seal structure of a separator for a fuel cell unit according to any one of claims 4 to 6,

the seal is also bonded to the face of the diaphragm that is connected to the side wall.

8. The seal structure of a separator for a fuel cell unit according to any one of claims 1 to 3,

the sealing member is bonded to the side wall of the rib.

Technical Field

The present invention relates to a seal structure of a separator for a fuel cell unit.

Background

Fuel cells that generate electricity by electrochemically reacting reaction gases are rapidly becoming widespread. Fuel cells have been drawing attention as a preferred energy source because of their high power generation efficiency and small environmental impact.

Among fuel cells, a polymer electrolyte fuel cell has a stack structure in which a plurality of fuel cell units are stacked. Each fuel cell unit sandwiches a Membrane Electrode Assembly (MEA) with a pair of separators. The membrane electrode assembly is a structure in which an electrolyte membrane is sandwiched between an anode electrode (anode) and a cathode electrode (cathode), and each electrode has a laminated structure of a catalyst layer and a Gas Diffusion Layer (GDL). The separator is in close contact with the gas diffusion layer, and forms a flow path for hydrogen and oxygen between the separator and the gas diffusion layer.

Such a fuel cell supplies hydrogen to the anode electrode and oxygen to the cathode electrode through the flow channel formed in the separator. Thereby generating electricity by an electrochemical reaction reverse to the electrolysis of water.

As shown in the drawings of patent document 1, an electrolyte membrane (reference numeral 55 in document 1) of the membrane electrode assembly is sealed at its end. As the sealing member, for example, a gasket (gasket main bodies 21 and 31) as described in patent document 1 is used. The gasket is elastically deformed in a direction orthogonal to the surfaces of the separators, and seals the electrolyte membrane of the membrane electrode assembly between the pair of separators. Such a seal structure using a gasket generates a certain degree of fastening force, and is therefore suitable for use in a metal separator.

As another structural example of sealing the electrolyte membrane of the membrane electrode assembly, a bonding seal member or an adhesive seal member may be used. These sealing members do not require a large fastening force, and therefore can be applied to a brittle separator such as a carbon separator.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-143479

Disclosure of Invention

Technical problem to be solved by the invention

Since the fuel cell generates electricity and increases the temperature, the gap between the pair of separators sandwiching the membrane electrode assembly is likely to fluctuate. Therefore, a sealing member having relatively high hardness, such as a bonded sealing member or an adhesive sealing member, cannot follow the fluctuation of the gap, and may peel off from the separator or break the separator in the case of a fragile separator.

On the other hand, when a gasket made of a rubber-like elastic material having relatively low hardness is used, the gasket is not suitable for a brittle separator because of its strong fastening force as described above.

The present invention seeks to provide a seal structure capable of following the variation of the gap between a pair of fuel cell separators without generating a large fastening force.

Means for solving the technical problem

One aspect of a seal structure for a fuel cell separator includes: a pair of spacers that face each other with an object member interposed therebetween and that have a rib that is in close contact with the object member and that forms a fluid flow path between the pair of spacers and the object member; and a seal member for overlapping the ribs of the pair of separators in a nested manner, and having an elastic seal member provided between side walls of the ribs facing each other.

Effects of the invention

A seal structure capable of following the variation of the gap between a pair of separators without generating a large fastening force can be realized.

Drawings

Fig. 1 is a schematic diagram conceptually showing a cell stack structure in which a plurality of fuel cell units are stacked.

Fig. 2 is a vertical sectional view of a seal structure that seals a gap between a pair of separators.

Fig. 3 is a vertical cross-sectional view showing a state of the sealing structure of the comparative example when the gap between the ribs of the pair of separators is varied from a predetermined state to an expanding direction.

Fig. 4 is a vertical cross-sectional view showing a state of the seal structure of the present embodiment when the gap between the ribs of the pair of separators changes from a predetermined state to an expanding direction.

Fig. 5 is a vertical sectional view showing another example of a separator for a fuel cell.

Fig. 6 is a vertical sectional view showing another example of the separator for a fuel cell.

Fig. 7 is a vertical sectional view showing still another example of a separator for a fuel cell.

Detailed Description

The embodiment will be described with respect to a seal structure of a separator for a fuel cell.

[ first embodiment ]

A first embodiment will be described with reference to fig. 1 to 4.

As shown in fig. 1, the fuel cell 1 has a stacked structure in which a plurality of fuel cells 2 are stacked. The fuel cell 2 has an electrolyte membrane 102 provided with a membrane Electrode assembly 101 called mea (membrane Electrode assembly) interposed between a pair of separators 11 for a fuel cell. The fuel cells 2 are stacked with a cooling surface sealing member 201 as a sealing member interposed therebetween. Although only two sets of fuel cell units 2 are depicted in fig. 1, several hundreds of sets of fuel cell units 2 are actually stacked to constitute the fuel cell 1.

The membrane electrode assembly 101 is a structure in which electrodes, not shown, are provided at the center portions of both surfaces of an electrolyte membrane 102. The electrodes have a laminated structure (neither shown) including a catalyst layer formed on the electrolyte membrane 102 and a Gas Diffusion Layer (GDL) formed on the catalyst layer. In such an electrode, one surface side of the electrolyte membrane 102 is used as an anode electrode (anode), and the opposite surface side thereof is used as a cathode electrode (cathode).

The fuel cell separator 11 is a flat plate-like member molded with a resin such as carbon, for example. Of course, the separator 11 is not limited to such a brittle member made of carbon, and a flat plate-like member that can be press-worked, such as a thin stainless steel plate, may be used as another example.

The separator 11 has a rectangular planar shape and is provided with an arrangement region 12 for arranging the membrane electrode assembly 101. Three openings are provided at positions offset from both end sides of the arrangement region 12, and are manifolds 13 for allowing a fluid used for power generation or generated by power generation to flow through the manifolds 13. The fluid flowing through the manifold 13 is fuel gas (hydrogen), oxidizing gas (oxygen), water produced by an electrochemical reaction during power generation, excess oxidizing gas, a refrigerant, or the like.

The manifold 103 is also provided on the electrolyte membrane 102 in alignment with the manifold 13 provided on the separator 11. These manifolds 103 are provided with three openings at positions offset from both end sides of the membrane electrode assembly 101.

The fuel cell 1 introduces a fuel gas (hydrogen) between the separators 11A facing one surface of the electrolyte membrane 102 provided with the membrane electrode assembly 101 and introduces an oxidizing gas (oxygen) between the separators 11B facing the other surface of the electrolyte membrane 102 by the manifolds 13 and 103. Cooling water serving as a coolant is introduced between the two sets of fuel cells 2 sealed by the cooling surface sealing member 201. At this time, the fuel gas, the oxidizing gas, and the cooling water flow through respective channels formed by the pair of separators 11(11A, 11B) that assemble the fuel cell 2.

The pair of separators 11 face each other with the electrolyte membrane 102 as a target member interposed therebetween, thereby forming the fuel cell unit 2. The separator 11 has ribs 14, and the ribs 14 are in close contact with the electrolyte membrane 102 to form a fluid flow path between the electrolyte membrane 102 and the separator 14. The space between the electrolyte membrane 102 and the bead 14A of the separator 11A forms a flow path for the fuel gas. The space between the electrolyte membrane 102 and the bead 14B of the separator 11B forms a flow path for the oxidizing gas. The spaces between the ribs 14A and 14B provided between the separators 11A of the fuel cell units 2 of one group and the separators 11B of the fuel cell units 2 stacked on top of each other form cooling water flow paths.

The fuel cell 2 has a seal structure on the outer peripheral edges of the separators 11, the membrane electrode assembly 101, and the manifolds 13 and 103. The seal structure includes: a cooling surface sealing member 201 interposed between the two groups of fuel cells 2; and a reaction surface sealing member 202 as a sealing member provided between the separator 11 and the membrane electrode assembly 101. Such a sealed structure makes the flow paths of the fuel gas and the surplus fuel gas, the flow paths of the oxidizing gas and the water produced by the electrochemical reaction during power generation, and the flow paths of the cooling water as the coolant independent from each other, thereby preventing mixing of different types of fluids.

As shown in fig. 2, the ribs 14 of the separators 11 overlap each other in a nested manner at the portions where the cooling surface seal member 201 and the reaction surface seal member 202 are provided. For example, the rib 14B of the separator 11B facing the surface opposite to the one surface of the electrolyte membrane 102 is formed larger than the rib 14A of the separator 11A facing the one surface of the electrolyte membrane 102 provided with the membrane electrode assembly 101, and the rib 14A enters the rib 14B in a non-contact state.

The cooling surface seal member 201 and the reaction surface seal member 202 are formed by a seal 203 having elasticity. As an example, a gasket molded from a rubber-like elastic material such as low-hardness vulcanized rubber is used for the seal 203. The seal 203 is disposed between the side walls 15 of the ribs 14(14A, 14B) facing each other and fixed by overlapping the same in a nested manner.

To secure the seal 203, various embodiments are allowed.

One possible embodiment is to provide the seal 203 with an adhesive property that can adhere to the side wall 15 of the bead 14. As a method for this, the seal structure of the present embodiment is a method in which the seal 203 is molded using a molded product of rubber having adhesiveness, and the seal 203 itself has adhesiveness.

As the rubber having adhesiveness, for example, a rubber adhesive containing a base polymer such as butyl rubber, polyisobutylene rubber, styrene-butadiene rubber, ethylene-propylene-diene rubber, and natural rubber can be used.

An additive may be added to the rubber that is the material of the seal 203. Examples of additives that can be blended include crosslinking agents, tackifiers, fillers, and antioxidants.

As another embodiment of providing the seal 203 with adhesiveness to the side wall 15 of the bead 14, for example, the seal 203 may have a multilayer structure of a low-hardness vulcanized rubber and an adhesive layer (see the fourth embodiment). The rubber having adhesiveness in such a case may be the above-mentioned butene rubber or the like, or may be blended with various additives.

Another embodiment allowed for fixing the seal 203 is a mode in which one side of the separator 11 is provided with adhesiveness or cohesiveness to fix the seal 203.

For example, the seal 203 may be fixed by applying an adhesive to the inner side wall 15A of the bead 14A of the separator 11A, and the seal 203 may be brought into close contact with the outer side wall 15B of the bead 14B of the separator 11B. The seal 203 may be fixed by applying an adhesive to the outer side wall 15B of the bead 14B of the separator 11B, and the seal 203 may be brought into close contact with the inner side wall 15A of the bead 14A of the separator 11A. Alternatively, the sealing material 203 may be fixed by applying an adhesive to the inner side walls 15A and 15B of the ribs 14A and 14B of the separators 11A and 11B.

When the adhesive is formed on one side of the rib 14, for example, a rubber adhesive using a base polymer such as butyl rubber, polyisobutylene rubber, styrene-butadiene rubber, ethylene-propylene-diene monomer rubber, or natural rubber can be used as the adhesive. In addition, various additives such as a crosslinking agent, a tackifier, a filler, an antioxidant and the like may be blended.

The shaping of the adhesive to the bead 14 can be achieved by, for example, coating with a dispenser, integral molding by injection molding or transfer molding, or post-application of shaped adhesive by compression molding or the like.

Another embodiment allowed for fixing the seal member 203 is a method of bonding the seal member 203 to the separator 11.

The sealing material 203 may be adhesively fixed to the inner side wall 15A of the bead 14A of the separator 11A with an adhesive, and the sealing material 203 may be brought into close contact with the outer side wall 15B of the bead 14B of the separator 11B. The sealing material 203 may be adhesively fixed to the outer side wall 15B of the bead 14B of the separator 11B with an adhesive, and the sealing material 203 may be brought into close contact with the inner side wall 15A of the bead 14A of the separator 11A. Alternatively, the sealing material 203 may be fixed to the inner side walls 15A and 15B of the ribs 14A and 14B of the separators 11A and 11B by an adhesive.

In such a configuration, the seal structure of the present embodiment achieves fluid sealing by the seal 203 interposed between the side walls 15 of the beads 14 of the partition plate 11 that are stacked in a nested manner. Therefore, the seal 203 can follow the variation in the gap between the pair of separators 11(11A, 11B) due to a temperature increase or the like caused by power generation without generating a large fastening force. The following description will be made while comparing with comparative examples.

Fig. 3 shows a state of the sealing structure of the comparative example when the gap between the ribs B of the pair of separators S varies from a predetermined state to an expanding direction. In the sealing structure of this comparative example, the beads B of the pair of separators S are brought into close contact with the top portions of each other via the seal SM. Therefore, when the predetermined gap between the ribs B is set to t1, the seal SM expands accordingly when the gap between the ribs B is enlarged to a dimension t 2. Although not shown, when the gap between the ribs B is narrow, the seal SM is compressed accordingly.

The sealing structure of the comparative example described above generates a sealing action by compressive deformation of the seal SM. With this configuration, a large tightening force is generated between the ribs B of the pair of separators S, and when the gap between the ribs B varies, the tightening force also varies greatly. Therefore, when a brittle material made of a resin such as carbon is used as the separator S, the separator S may be broken.

Fig. 4 shows a state of the seal structure of the present embodiment when the gap between the ribs 14 of the pair of separators 11 changes from a predetermined state to an expanding direction. As in the case of the comparative example, even if the gap size between the pair of separators 11 varies from t1 to t2, the size between the side walls 15 of the bead 14 where the seal 203 is interposed does not vary. The dimension t4 between the side walls 15 is maintained to be the same as the dimension t3 when the gap between the partitions 11 varies. At this time, a shearing force is generated in the seal 203, and it is difficult for a large force to act on the bead 14 of the separator 11 as compared with a compression force. Therefore, a seal structure that can follow the change in the gap between the pair of separators 11 without generating a large fastening force can be realized, and a fragile separator 11 made of a resin such as carbon can also be used.

[ second embodiment ]

A second embodiment will be described with reference to fig. 5. The same portions as those of the first embodiment are shown with the same reference numerals and the description is omitted.

As shown in fig. 4, the present embodiment relates to a rising angle θ of the side walls 15 of the ribs 14 facing each other of the pair of separators 11 from the separator 11. The rising angle θ of the side wall 15 of the first embodiment from the partition 11 is a right angle, that is, 90 °. The rising angle θ of the side wall 15 is preferably in the range of 5 to 90 °. The rising angle θ of the side wall 15 in the present embodiment is about 70. That is, the side walls 15 of the ribs 14 facing each other of the pair of partitions 11 are inclined with respect to the partitions 11.

The seal 203 is of parallelogram shape in cross section and is in contact with the face of the partition 11 which is connected to the side wall 15. Such a seal 203 is bonded or adhered not only to the side wall 15 of the bead 14 but also to the face of the partition 11 connected to the side wall 15.

In such a configuration, since the side walls 15 of the beads 14 are inclined with respect to the separators 11, when the fuel cell unit 2 is assembled by stacking a pair of separators 11, the seal 203 can be interposed between the beads 14 only by moving the beads 14 in the direction in which they approach each other. Therefore, the fuel cell unit 2 and the fuel cell 1 can be easily assembled.

[ third embodiment ]

A third embodiment will be described with reference to fig. 6. The same portions as those of the first and second embodiments are shown with the same reference numerals and description thereof is omitted.

In the seal structure of the present embodiment, the length of the seal 203 bonded or adhered to the surface of the bead 14 of the partition plate 11 is made shorter than the length between the side walls 15 of the bead 14. As a result, when the gap between the pair of separators 11 fluctuates, the seal 203 is easily deformed in the shearing direction, and the pressure applied to the separators 11 can be further reduced.

[ fourth embodiment ]

A fourth embodiment will be described with reference to fig. 7. The same portions as those of the first and second embodiments are shown with the same reference numerals and description thereof is omitted.

In the present embodiment, as a structure for fixing the seal 203 to the separator 11, an adhesive layer 204 is provided on the seal 203, instead of being formed on the side wall 15 of the bead 14 with an adhesive. The seal 203 is a low-hardness vulcanized rubber, and the adhesive layer 204 is provided on the surface of the seal 203 that is joined to the side wall 15 of the bead 14.

In such a structure, the seal 203 is bonded to the side wall 15B of the separator 11B by the single-sided adhesive layer 204. In this state, the side wall 15A of the separator 11A is bonded to the adhesive layer 204 on the opposite side by overlapping the separator 11A and the separator 11B. Thus, the seal 203 is provided between the side walls 15A and 15B of the stacked pair of separators 11A and 11B.

In the present embodiment, since the adhesive layer 204 is provided on the seal 203 itself, the separator 11 does not need to be processed for adhering and fixing the seal 203, and thus the manufacturing can be facilitated.

[ modified examples ]

Various modifications and changes are allowed in the implementation.

For example, the angle of the bead 14 with respect to the separator 11 is not limited to 90 ° (first embodiment) or about 70 ° (second to fourth embodiments). The angle can be set to various angles within the range of 5-90 degrees. In the pair of separators 11A, 11B constituting the fuel cell unit 2, the rising angles of the respective beads 14A, 14B do not need to be uniform, and may rise at different angles.

In other implementations, all modifications and changes are allowed.

Description of the reference numerals

1 Fuel cell

2 Fuel cell Unit

11 baffle plate

11A baffle

11B baffle

12 configuration area

13 manifold

14 convex rib

14A convex rib

14B convex rib

15 side wall

15A side wall

15B side wall

101 membrane electrode assembly

102 electrolyte membrane (object member)

103 manifold

201 Cooling surface sealing member (sealing member)

202 reaction surface sealing member (sealing member)

203 sealing element

204 adhesive layer

S baffle

B convex rib

SM sealing member