JP6290603B2 - Gasket for fuel cell - Google Patents

Description

The present invention is a liquid fuel to a direct fuel supply type supplied directly to the fuel side electrode, and a gasket for sealing a flow path formed between the fuel cell stack in liquids fuel cell, the fuel The present invention relates to a gasket in which gas diffusion layers (hereinafter abbreviated as GDL (GDL: Gas Diffusion Layer)) on both sides in the thickness direction of a power generation body of a battery cell are integrated.

  Conventionally, development of a direct liquid fuel type fuel cell that directly supplies liquid fuel as a fuel cell mounted on a vehicle has been promoted. For example, a direct methanol type fuel cell (DMFC) is known. Yes. The basic structure of this type of fuel cell is a membrane-electrode assembly (hereinafter abbreviated as MEA (MEA)) in which a negative electrode layer (anode) and a positive electrode layer (cathode) are provided on both surfaces of an electrolyte membrane (ion exchange membrane). Membrane Electrode Assembly)) is sandwiched between separators made of carbon, synthetic resin or metal, and this is used as one power generation unit (fuel cell). And although the electromotive force by each fuel battery cell is low, a required electromotive force can be obtained by stacking a large number of fuel battery cells and electrically connecting them in series. Yes.

  In this type of fuel cell, the reducing agent fuel supplied to the anode side of the MEA is reduced to extract electrons and generate electric power. As the reducing agent, alcohol such as methanol, hydrazine or the like is used. On the other hand, oxygen, water, or the like is used as the oxidant supplied to the cathode side of the MEA. In addition, when cooling is necessary, water and antifreeze are also distributed. In order to supply these types of fluids to the fuel cell, the flow paths of these fluids are used so that these fluids are not dissipated from the space to be supplied or other fluids are not mixed. Therefore, each fuel battery cell must be sealed with a rubber-like elastic material, in particular, a gasket formed of a material having good moldability such as a rubber elastic body, a thermoplastic elastomer, or a thermosetting resin. Is incorporated.

  The gasket has a rubber-like elastic body part (hereinafter referred to as "gasket body") formed integrally with a separator, MEA, GDL or the like, which is a component of the fuel cell, thereby handling the fuel cell stack during assembly. Can be improved. Normally, when the gasket body is integrated with the separator, the separator is made of carbon, synthetic resin, or metal, so it is relatively rigid and easy to handle. A groove can be provided, or an end portion of the separator or a manifold hole formed in the separator can be used as a positioning mark for accurate positioning and lamination.

  On the other hand, when the gasket main body is integrated with the GDL, the gasket main body is generally shaped continuously all around so as not to be interrupted at the outermost periphery of the GDL. When the independent GDLs are arranged on the anode side and the cathode side in the MEA, the gasket main body is also separately molded into each GDL. Therefore, at the time of stacking, a fuel cell is obtained by arranging the anode side GDL and the cathode side GDL with the MEA carrying the anode and cathode interposed therebetween. However, GDL is made of a porous material such as carbon cloth, carbon felt, metal fiber cloth, etc., and is easily deformed during handling. Further, since it is made of a plate shape or a sheet shape, GDL itself has a mark that can be used for positioning. Therefore, it is difficult to position the gasket bodies (between gaskets) integrated in the GDL independent on the anode side and the cathode side with high accuracy like those molded integrally with the separator. There was a concern of causing a positional shift between the gasket and the MEA.

  If there is a displacement between the laminated gaskets, the gasket will fall due to a decrease in surface pressure or moment, and the compression reaction force of the gasket body due to lamination becomes unstable, or the sealing performance becomes unstable. There was a risk of it.

JP 2002-42838 A

The present invention has been made in view of the above points, and the technical problem thereof is a direct fuel supply type in which liquid fuel is directly supplied to a fuel side electrode, and the gasket body is used as a gas diffusion layer. in the gasket for liquids fuel cell Ru with an integrated structure is to prevent the positional deviation between the gasket during lamination occurs.

As means for effectively solving the above technical problem, the fuel cell gasket according to the invention of claim 1 is a gasket used for a liquid fuel cell, and is an anode of a membrane-electrode composite in a fuel cell. The gas diffusion layers arranged on the cathode side and the cathode side are integrally molded with a gasket body in which a sealing lip having a raised shape is formed on the plate-like base so as to surround the outer periphery of these gas diffusion layers. , the plate-like base portion of the anode side and the cathode side the gasket body which is molded into the gas diffusion layer of one of, fitting an outer peripheral edge of the plate-shaped base portion of the gasket body which is molded to the other of the gas diffusion layer A step surface that can be fitted or loosely fitted is formed.

If comprised in this way, the gasket main body shape | molded by one gas diffusion layer in the anode side and the cathode side, and the gasket main body shape | molded by the other gas diffusion layer are the one step surface and the other plate shape. in a state where the outer edge of the base portion is fitted or loosely fitted film - from being stacked on the anode side and the cathode side of the electrode assembly, each gasket is precisely positioned to each other.

Fuel cell gaskets according to the invention of claim 2 is the structure of claim 1, the plate-like base portion of the anode side and the cathode side the gasket body which is molded into the gas diffusion layer of one of said step located on the inner peripheral side surface, the film - is obtained by forming the outer edge of the electrode assembly and the fit or loosely fitted possible second step surface.

If comprised in this way, while each gasket is positioned with high precision mutually, the 2nd level | step difference surface formed in the plate-shaped base part of one gasket main body among an anode side and a cathode side, and the outer periphery of a membrane electrode assembly The membrane electrode assembly is also positioned with high accuracy by the end fitting or loose fitting.

  According to the fuel cell gasket according to the present invention, the gaskets are positioned with high accuracy at the time of stacking, so that it is possible to effectively prevent the compression reaction force and the sealing surface pressure from becoming unstable due to misalignment. The reliability of the fuel cell and the reliability of the fuel cell can be improved.

It is explanatory drawing which shows schematic structure of the fuel cell to which the gasket for fuel cells which concerns on this invention is applied. It is a top view which shows the cell of the fuel cell to which the gasket for fuel cells which concerns on this invention is applied. It is principal part sectional drawing of the non-laminated state which cut | disconnects and shows preferable 1st embodiment of the gasket for fuel cells which concerns on this invention in the AA position in FIG. It is principal part sectional drawing of the lamination | stacking state which cut | disconnects and shows preferable 1st embodiment of the gasket for fuel cells which concerns on this invention in the AA position in FIG. FIG. 5 is a cross-sectional view of a main part in a non-laminated state showing a second preferred embodiment of the gasket for a fuel cell according to the present invention cut at the position AA in FIG. 2. FIG. 3 is a cross-sectional view of a main part in a laminated state showing a second preferred embodiment of the gasket for a fuel cell according to the present invention by cutting at a position AA in FIG. 2.

  Hereinafter, preferred embodiments of a gasket for a fuel cell according to the present invention will be described in detail with reference to the drawings. First, FIG. 1 shows a schematic configuration of a fuel cell to which a fuel cell gasket according to the present invention is applied, and FIG. 2 shows a fuel cell as one power generation unit in the fuel cell.

  That is, this type of fuel cell has a membrane-electrode assembly (hereinafter abbreviated as MEA) 1 in which a negative electrode layer (anode) is provided on one surface of an electrolyte membrane and a positive electrode layer (cathode) is provided on the other surface. A plate-like or sheet-like gas diffusion layer (hereinafter abbreviated as GDL) made of a porous material having innumerable fine through-holes that allow gas to flow from both sides in the thickness direction, such as carbon cloth, carbon felt, and metal fiber cloth. 2) and 3) are sandwiched by separators 4 and 5 made of carbon, synthetic resin or metal, and this is used as a fuel cell 10 which is the minimum unit of power generation. The fuel cell stack is configured by being integrated by a tightening mechanism such as the illustrated bolt or nut.

  On the outer peripheral side of one GDL 2 (hereinafter referred to as the first GDL 2), a first gasket body 6 made of a rubber-like elastic material (rubber elastic body, thermoplastic elastomer having rubber-like elasticity, thermosetting resin, etc.) is integrated. A second gasket body 7 made of the same rubber-like elastic material as that of the first gasket body 6 is integrally formed on the outer peripheral side of the other GDL 3 (hereinafter referred to as second GDL 3).

  The first GDL2 is stacked on one of the anode side and the cathode side of the MEA1, and the second GDL3 is stacked on the other of the anode side and the cathode side of the MEA1. The first gasket body 6 and the second gasket body 7 correspond to the gasket body described in claim 1.

A plurality of manifold holes 4a, 5a, and 6a are formed in the separators 4 and 5 and the first gasket body 6 integrally formed with the first GDL 2, and the manifold holes 4a of the separators 4 and 5 are formed in a stacked state. , a reducing agent (liquids fuels) by 5a and manifold holes 6a of the first gasket body 6 is polymerized (communication) with each other, so that the supply passage and the discharge passage (manifold) 10a of the oxidizing agent and the coolant are formed It has become.

  In this fuel cell, in each fuel cell 10, the reducing agent flowing through the manifold hole is supplied to the anode side of the MEA 1 via one GDL of the first GDL 2 and the second GDL 3, and the other manifold hole Is supplied to the cathode side of the MEA 1 via the other GDL of the first GDL2 and the second GDL3, and power is generated by a reaction that generates water from hydrogen atoms of the reducing agent and oxygen of the oxidizing agent. It is what happens. And although the electromotive force by each fuel cell 1 is low, by obtaining a fuel cell stack in which a large number of fuel cells 1 are stacked and electrically connected in series, the necessary high voltage is obtained. is there.

  FIGS. 3 and 4 show, as a preferred first embodiment of the fuel cell gasket according to the present invention, the MEA 1, the first GDL 2, the first gasket main body 6 integrated with the MEA 1, the second GDL 3, and the integral with the second GDL 3. The 2nd gasket main body 7 of this is cut | disconnected and shown by the AA position of FIG.

  As shown in FIG. 3, the first gasket body 6 surrounds the outer periphery of the first GDL 2 by a part of the rubber-like elastic material impregnating and curing the edge of the first GDL 2. It is molded integrally. Reference numeral 21 indicates a region (impregnated portion) in which the first GDL 2 is impregnated with the rubber-like elastic material of the first gasket body 6.

  The first gasket body 6 has an outer periphery of the first GDL 2 (an outer periphery of the impregnated portion 21) on a surface (the lower surface in FIG. 3) facing the opposite side in the thickness direction with respect to the laminated surface of the plate-like base 61 with the MEA 1. ) And a seal lip 62 having a mountain-shaped ridge shape extending so as to surround the outer periphery of the manifold hole 6a, and a seal lip 63 having a mountain-shaped ridge shape extending so as to surround the outer periphery of the manifold hole 6a. 3 (upper surface in FIG. 3), a seal lip 64 having a mountain-shaped raised section extending so as to surround the outer periphery of the manifold hole 6a back to back with the seal lip 63, and a step surface 65 extending so as to surround the outer periphery of the MEA 1. Is formed. The step surface 65 is formed so as to form an inner peripheral surface of the protrusion 66 lower than the seal lip 64.

  Further, the plate-like base 61 of the first gasket body 6 is relatively thicker on the outer peripheral side than the inner peripheral side with respect to the step surface 65, and on the inner peripheral side from the step surface 65, the first GDL 2 They are formed to have approximately the same thickness.

  On the other hand, the second gasket body 7 is integrally formed so as to surround the outer periphery of the second GDL 3 by impregnating and curing a part of the rubber-like elastic material on the edge of the second GDL 3. Yes. Reference numeral 31 indicates a region (impregnated portion) in which the first GDL 2 is impregnated with the rubber-like elastic material of the second gasket body 7.

  The second gasket main body 7 has an outer periphery of the second GDL 3 (an outer periphery of the impregnated portion 31) on a surface (upper surface in FIG. 3) facing the laminated surface with the MEA 1 in the plate base 71. A seal lip 72 having a ridge shape with a mountain-shaped cross section extending so as to surround the outer periphery) is formed.

  Further, the plate-like base 71 of the second gasket body 7 is formed to have a thickness substantially equal to that of the second GDL 3, and the size of the planar shape of the outer peripheral end 71a is the step surface of the first gasket body 6. Therefore, the second gasket body 7 can be fitted into the inner periphery of the stepped surface 65 as shown in FIG. Further, the height of the step surface 65 is equal to or greater than the sum of the thicknesses of the plate-like base portions of the MEA 1 and the second gasket body 7.

  In the laminated state shown in FIG. 4, the MEA 1 is separated from both sides in the thickness direction through the first GDL 2 and the first gasket body 6 integral with the first GDL 2, and the second GDL 3 and the second gasket body 7 integral with the separator 4. , 5, the fuel battery cell 10 is configured. At this time, the outer peripheral portion of the MEA 1 is tightly sandwiched between the first gasket body 6 and the second gasket body 7 on both sides thereof, and the seal lips 62, 63, 64 formed on the first gasket body 6 and the second gasket. The seal lip 72 formed on the main body 7 is in close contact with the separators 4 and 5 in an appropriately compressed state, and thereby, the periphery of the power generation region where the MEA 1, the first GDL 2 and the second GDL 3 are stacked is sealed. At the same time, the flow path is sealed so that the reducing agent or the oxidizing agent does not leak from the flow path between the manifold holes 4a, 5a of the separators 4, 5 and the power generation region.

  According to the first embodiment configured as described above, the first gasket main body 6 integrally formed with the first GDL 2 and the second gasket main body 7 integrally formed with the second GDL 3 at the time of lamination. Since the stepped surface 65 formed on the first gasket body 6 and the outer peripheral end 71a of the plate-like base 71 of the second gasket body 7 are loosely fitted to each other, they are positioned with high accuracy.

  Accordingly, the first gasket body 6 integrally formed with the first GDL 2 having low rigidity and the second gasket body 7 integrally formed with the second GDL 3 having low rigidity can be easily positioned with respect to each other in the lamination process. In addition, since the seal lip 62 formed on the first gasket body 6 and the seal lip 72 formed on the second gasket body 7 are compressed at the same position, the compression reaction force of the seal lips 62, 72 due to lamination is reduced. It does not become unstable or the sealing performance becomes unstable.

  Next, FIG. 5 and FIG. 6 show, as a second preferred embodiment of the fuel cell gasket according to the present invention, the MEA 1, the first GDL 2, the first gasket body 6 integrated with the MEA 1, the second GDL 3, and the second GDL 3. The 2nd gasket main body 7 integral with is cut | disconnected and shown by the AA position of FIG.

  In this second embodiment, the difference from the first embodiment described above is that the first gasket body 6 molded integrally with the first GDL 2 and the second gasket molded integrally with the second GDL 3 The second step surface 67 that can be loosely fitted to the outer peripheral end 1a of the MEA 1 is formed on the inner peripheral side of the stepped surface 65 that can be loosely fitted to the outer peripheral end 71a of the plate-like base 71 of the main body 7. is there.

  The second step surface 67 is formed so as to form the inner peripheral surface of the second protrusion 68 having a protrusion height lower than that of the protrusion 66 forming the step surface 65. A third step surface 71 b that can be loosely fitted to the second protrusion 68 is formed in the vicinity of the outer peripheral end 71 a of the plate-like base 71 of the second gasket body 7. Other parts can be configured in the same manner as in the first embodiment.

  According to the second embodiment configured as described above, similarly to the first embodiment, the first gasket body 6 integrally formed with the first GDL 2 and the second GDL 3 are laminated at the time of lamination. The integrally molded second gasket main body 7 has a height difference between the stepped surface 65 formed on the first gasket main body 6 and the outer peripheral end 71a of the plate-like base 71 of the second gasket main body 7. Positioned with accuracy.

  In addition, the plate-like base 71 of the second gasket body 7 is also positioned by loosely fitting the third stepped surface 71b and the second protrusion 68 during lamination, and the MEA 1 also has an outer peripheral end 1a. By loosely fitting with the second step surface 67 by the second protrusion 68, the MEA 1 and the GDL (first GDL2, second GDL3) and the gasket main body (the first gasket main body 6, the second gasket main body 7). ) Is positioned with high accuracy.

  Therefore, a sheet-like MEA 1 without a mark that can be used as a positioning in itself in the lamination process, and a first gasket body 6 integrally formed with a plate-like or sheet-like GDL 2 without a mark that can be used as a positioning in itself, The operation of positioning the second gasket body 7 integrally formed in the plate-like or sheet-like GDL 3 having no mark that can be used for positioning itself can be performed more easily, and is formed on the first gasket body 6. Since the seal lip 62 and the seal lip 72 formed on the second gasket body 7 are compressed at the same position, the compression reaction force of the seal lips 62 and 72 due to lamination becomes unstable or the sealing performance becomes unstable. It will never become.

  In the first and second embodiments described above, the seal lips 62 and 72 that seal the periphery of the power generation region in which the MEA 1, the first GDL2, and the second GDL3 are stacked, and the seal that seals the periphery of the manifold 10a. Although the lips 63 and 64 are formed independently of each other, a seal lip that seals the periphery of the power generation region may be formed to extend so as to surround a part of the manifold 10a.

1 MEA (membrane-electrode composite)
2 First GDL (gas diffusion layer)
3 Second GDL (gas diffusion layer)
4,5 Separator 6 First gasket body (gasket body)
65 Stepped surface 66 Projection 67 Second stepped surface 68 Second projection 7 Second gasket body (gasket body)

Claims (2)

A gasket used for a liquid fuel cell, wherein a gas diffusion layer disposed on each of an anode side and a cathode side of a membrane-electrode complex in a fuel cell unit is surrounded by a plate so as to surround the outer periphery of these gas diffusion layers. gasket body which sealing lip is formed on Jo base forms a ridge shape are integrally formed, a plate-shaped base of the anode and cathode sides said gasket body formed into the gas diffusion layer of one of the other fuel cell gaskets, wherein the forming the outer peripheral edge portion and the fit or loosely possible stepped surface of the plate-shaped base portion of the gasket body which is formed into the gas diffusion layer. A plate-like base portion of the anode side and the cathode side the gasket body which is molded into the gas diffusion layer of one of the, located on the inner peripheral side of the stepped surface, the film - fitted with the outer peripheral edge portion of the electrode assembly The fuel cell gasket according to claim 1, wherein a second stepped surface that can be joined or loosely fitted is formed.

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