JP2007157431A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal structure for a fuel cell having high sealing capability. <P>SOLUTION: In the fuel cell having an electrolyte assembly comprising an electrolyte and an electrode; a separator having a flow passage making flow at least one fluid out of several kinds of fluids on the surface; and an opening passing through the surface in order to supply/exhaust the corresponding fluid out of a plurality of fluids to/from the flow passage; and a sealing material arranged in the flow passage and the periphery of the opening, the seal material has a partial opening seal in which one portion connecting to the flow passage out of the periphery of the opening of at least one fluid is opened and the sealing material is arranged in other portions; and a closing seal arranged so as to surround the whole periphery of the opening part of other fluids, and a connection part of the seal material continuing from the partial opening seal to the seal material of the flow passage has a corner part, and a load support is installed in the vicinity of the corner part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell.

  A solid polymer electrolyte fuel cell is a membrane / electrode assembly comprising an electrolyte membrane comprising an ion exchange membrane, an anode electrode disposed on one surface of the electrolyte membrane, and a cathode electrode disposed on the other surface of the electrolyte membrane ( Each cell composed of MEA (Membrane-Electrode Assembly) and a separator is stacked to be used as a cell stack.

  The separator has a flow path and an opening (manifold) for supplying fuel gas and oxidant gas to both the anode and the cathode, respectively, and further supplies a cooling medium (for example, pure water) for cooling the fuel cell. And a flow path and an opening (manifold).

  The reaction gas (fuel gas and oxidant gas) and the cooling medium flow through the manifold for each fluid formed inside the fuel cell, and are supplied to each cell in a state of being separated from each other, and the outlet opening ( It is recovered from the manifold) and discharged outside the fuel cell. In order to prevent separation of each fluid flowing through such an opening (manifold) and leakage of each fluid to the outside, a seal material is usually provided around the opening (manifold) and the separator.

  FIG. 4 shows an arrangement of a general integrated seal 70 installed on the separator surface on which the cooling medium flow path is formed. Sealing material is installed around the fuel gas openings (manifolds) 33a and 33b and the oxidant gas openings (manifolds) 34a and 34b so as to completely surround the openings (manifolds). The material is referred to as a “closed seal”). In contrast, in order to supply and discharge the cooling medium in the separator surface, the sealing material installed around the cooling medium openings (manifolds) 32a and 32b is in a state where the side connected to the flow path 26 is open. (Hereinafter, the sealing material having such a shape is referred to as a “partial opening seal”).

  On the other hand, since different fluids (for example, fuel gas) flow on the back side of the separator, partial open seals are installed around the openings (manifolds) 33a and 33b on the back side, and closing seals are placed around the other openings (manifolds). Installed. Therefore, the positional relationship between the closing seal and the partial opening seal is different between the front and back sides.

  When separators having such a seal arrangement are stacked and a tightening load is applied in the stacking direction, a seal region where the tightening load is difficult to be applied uniformly (for example, a portion where the partially opened seal is opened) is generated. In such a sealing region, the sealing performance is lowered, and fluid leakage is likely to occur.

Therefore, in order to make it possible to apply a uniform load to the entire seal portion of the separator, for example, separately in the open portion of the seal material 70 (hereinafter also referred to as “open portion”) around the cooling medium openings 32a and 32b. A method is shown in which a sealing material is installed in an island shape and the load in the stacking direction is made uniform (see Patent Document 1).
JP 2004-335178 A

  However, in the corner portion R of the sealing material, the position of the sealing material is likely to be shifted compared to the straight portion of the sealing material, and the load in the separator stacking direction tends to be non-uniform. Therefore, even if the method of Patent Document 1 is used, it cannot be said that the tightening load of the sealing material is uniform. In particular, since there is no sealing material in the open part of the partial opening seal, there is a problem that the position shift is large in the corner portion R of the partial opening seal, and the tightening load of the sealing material tends to be uneven.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a fuel cell seal structure with good sealing performance by improving the uniformity of the tightening load of the sealing material around the fluid opening. And

  In order to achieve the above object, in the present invention, an electrolyte assembly composed of an electrolyte and an electrode, a flow channel portion for circulating at least one fluid among a plurality of types of fluids on the surface, and a plurality of types of fluids in the flow channel unit. A separator having an opening formed through the surface in order to supply and discharge the corresponding fluid, and a sealing material disposed around the flow path and the opening on the surface of the separator, A seal material is a partially open seal in which a part connected to the flow path part of the periphery of the opening part of at least one fluid is opened and the seal material is arranged in the other part; A sealing seal disposed so as to surround the entire periphery of the opening of the other fluid, and a connecting portion of the sealing material connected from the partially open seal to the sealing material of the flow path has a corner portion, and the corner In the vicinity of the parts the fuel cell, wherein the load bearing body is provided it is provided. By installing the load support at such a position, the sealing material is hardly displaced, and even if the position of the sealing material is deviated, a uniform load can be applied to the entire sealing material.

  Here, the sealing material may have a structure in which the closing seal and the partial opening seal are integrated.

  The load support may be made of the same material as the sealing material.

  Further, the load support may be connected to a corner portion of the closing seal.

  For example, the load support is disposed in parallel with the flow of fluid flowing between the opening in which the partial opening seal is disposed and the flow path. Thereby, the installation process of a load support body is simplified.

  Alternatively, as another aspect, the load support may be a protrusion provided on the separator surface. Also in this case, it is possible to omit the load supporting body installation step.

  As yet another aspect, a plurality of load supports may be disposed in a portion connected to the flow path portion around the opening where the partial opening seal is disposed. Thereby, more effective load equalization is achieved.

  The corner portion of the sealing material may have a continuous curved shape. In general, when the corner portion has a curved shape, the sealing material tends to shift more easily, but in the present invention, even with such a sealing material shape, the non-uniformity of the tightening load applied to the sealing material is suppressed. Can do.

  In the fuel cell seal structure of the present invention, it is possible to suppress non-uniformity in the tightening load of the sealing material around the fluid opening.

  The best mode of the present invention will be described below with reference to examples.

  The fuel cell targeted by the present invention is a solid polymer electrolyte fuel cell 10. The fuel cell 10 of the present invention is mounted on, for example, a fuel cell vehicle. However, it may be used for other than automobiles.

  First, the configuration of the solid polymer electrolyte fuel cell will be described.

  As shown in FIGS. 1, 2, and 3, the solid polymer electrolyte fuel cell 10 is formed by stacking cells having a membrane / electrode assembly (MEA), a separator, and a resin frame. The MEA comprises an electrolyte membrane 11 made of an ion exchange membrane, an electrode 14 (anode) comprising a catalyst layer 12 disposed on one surface of the electrolyte membrane 11, and an electrode 17 comprising a catalyst layer 15 disposed on the other surface of the electrolyte membrane 11 ( Cathode). A diffusion layer 13 and a diffusion layer 16 are provided between the electrodes 14 and 17 and the separator. The separator is composed of a first member 18A and a second member 18B. These members include reaction gas passages 27 and 28 for supplying fuel gas and oxidant gas to the electrodes 14 and 17, and fuel cell cooling. A cooling medium flow path 26 through which the refrigerant for cooling flows. A module 19 is formed by stacking one or more layers of cells (in the example of FIG. 1, one module is configured by one cell), the modules 19 are stacked to form a module group, and both ends of the module group in the cell stacking direction. The terminal 20, the insulator 21, and the end plate 22 are arranged, the cell stack is clamped in the cell stacking direction, and is fixed with a sintered member 24 (for example, a tension plate) and bolts 25 or nuts extending in the cell stacking direction. Is configured. The cooling medium flow path 26 is provided for each cell or for each of a plurality of cells.

  Next, a method for laminating the separator and the resin frame will be described.

  As shown in FIG. 3, the first member 18A and the second member 18B of the separator have a fuel cell reaction part 29 (part where the electrode reaction of the fuel cell occurs), but the resin frames 18C and 18D are the same part. Is a hollow hole. The first member 18A of the separator and the resin frame 18C are arranged on the anode electrode side of the MEA, and the first member 18A of the separator partitions the fuel gas and the cooling medium on the front and back. The separator second member 18B and the resin frame 18D are disposed on the cathode electrode side of the MEA, and the separator second member 18B partitions the oxidant gas and the cooling medium on the front and back sides. The separator first and second members 18A and 18B are made of metal, and are hereinafter referred to as metal separators 18A and 18B, respectively. The metal separators 18A and 18B are made of a material obtained by plating a metal plate such as stainless steel with a conductive metal such as nickel or gold. The metal separators 18A and 18B serve to form a conductive path between adjacent cells.

  In the fuel cell reaction part 29, since the resin frames 18C and 18D are hollowed out, the metal separators 18A, MEA, and the metal separator 18B are laminated in this order. The resin frames 18C and 18D are the metal separator 18A and the resin frame. 18C, resin frame 18D, and metal separator 18B are laminated in this order.

  As shown in FIG. 5, a fuel gas flow path 27 is formed on the MEA side surface of the fuel cell reaction part 29 of the metal separator 18A, and a cooling medium flow path 26 is formed on the surface opposite to the MEA. ing. Similarly, an oxidant gas flow path 28 is formed on the MEA side surface of the fuel cell reaction part of the metal separator 18B, and a cooling medium flow path 26 is formed on the surface opposite to the MEA. The fuel gas channel 27 and the oxidant gas channel 28 correspond to each other across the MEA. The coolant flow path 26 on the surface of the metal separator 18A of one cell opposite to the MEA of the fuel cell reaction portion, and the coolant flow on the surface of the metal separator 18B of the adjacent cell opposite to the MEA of the fuel cell reaction portion The channel 26 communicates without being separated in the cell stacking direction.

  In the fuel cell reaction unit 29, the surface opposite to the MEA at the bottom of the concave groove of the fuel gas flow path 27 of one cell and the side opposite to the MEA at the bottom of the concave groove of the oxidant gas flow path 28 of the adjacent cell This contact surface forms a conductive path between the metal separator 18A of one cell and the metal separator 18B of the adjacent cell.

  Usually, a plurality of fuel gas channels 27 are formed in parallel, and a plurality of oxidant gas channels 28 are also formed in parallel.

  As shown in FIGS. 3 and 4, openings are formed in facing portions 30 and 31 of the metal separators 18A and 18B and the resin frames 18C and 18D that face each other with the fuel cell reaction portion 29 interposed therebetween. The arrangement in the figure is an example of a so-called counter flow type channel arrangement. In this arrangement, one of the corresponding parts 30, 31 is provided with an inlet side cooling medium opening 32a, an outlet side fuel gas opening 33b, and an inlet side oxidant gas opening 34a, and the other 31 is provided with an outlet side cooling medium. A medium opening 32b, an inlet-side fuel gas opening 33a, and an outlet-side oxidant gas opening 34b are provided. On the other hand, in the case of a so-called parallel flow method in which the flow directions of the fluids are equal to each other, one of the corresponding portions 30 and 31 facing each other across the fuel cell reaction portion 29 has an opening on the inlet side of each fluid. The other 31 is provided with an opening on the outlet side of each fluid.

  As shown in FIGS. 4, 5, and 6, between the cells, an integrated sealing material 70 is disposed between adjacent metal separators. The sealing material 70 includes cooling medium openings 32a and 32b, and a fuel gas opening 33. a, 33b and oxidant gas openings 34a, 34b are separated from each other, and these fluids are sealed. As such a sealing material, fluorine-based or silicone-based rubber or EPDM (ethylene propylene rubber) is usually used. On the other hand, since the resin frame (18C or 18D) is installed via the adhesive 50 on the surface side where the sealing material 70 of the metal separator (18A or 18B) is not installed, the adhesive 50 is present on this surface. Functions as a sealing material. When a tightening load is applied to such a fuel cell stack 23 in the cell stacking direction, a load is applied to the sealing material 70 to form a fluid seal structure.

  Here, the features of the seal structure of the present invention will be described in detail by taking as an example the arrangement of the sealing material on the separator surface where the cooling medium flow path 26 shown in FIG. 4 is formed.

  As described above, each fluid is supplied to the reaction section 29 on the surface of a predetermined separator through the inlet opening of each fluid, and discharged through the outlet opening of each fluid. Therefore, the closing seal of the integrated sealing material 70 cannot be provided around the cooling medium openings 32a and 32b on the separator surface on which the cooling medium flow path 26 is formed. In this case, a partial opening seal 80 is provided around the cooling medium openings 32a and 32b.

  In the prior art, when a separator having a sealing material installed in such an arrangement is laminated, the corner portion R of the sealing material is usually in the stacking direction after assembly even if it is installed at a predetermined position in the manufacturing stage. When viewed, a large shift is likely to occur compared to the straight portion of the seal material. In particular, in the portion where the closing seal 75 and the partial opening seal 80 are connected, since there is no sealing material in the open portion 85 of the partial opening seal 80, the influence of the displacement of the corner portion R of the closing sealing material 75 is affected. It cannot be relieved by the partial opening seal 80, and when viewed from the separator stacking direction, a non-uniform tightening load is generated at this corner portion.

  Further, as described above, when the resin frame is bonded to the metal separator with an adhesive, a sufficient load is not applied to the corner portion R described above, and as a result, the corresponding portion in the separator (circle D in the separator lamination diagram 6). The adhesive 50 in the portion covered with (1) receives the pressure of the internal fluid alone. Therefore, the adhesive 50 is easily peeled off, and when the peeling occurs, fluid leaks.

  Therefore, in order to solve these problems, when a projection or the like that receives a load is installed in the open part 85 of the partial open seal 80, this part becomes an obstacle to the fluid that is supplied from the opening and flows on the surface of the separator, Uniform in-plane flux distribution is hindered and pressure loss occurs on the inlet and outlet sides of the fluid in the separator surface. Furthermore, when the corner portion R of the sealing material is not a right-angled shape but a curved shape, there is a portion where the sealing material does not exist in the corner portion R. Therefore, even if a projection or the like that receives a load is installed in the open portion 85 of the partial open seal 80, there is no support body that receives the load near the corner portion R. A load is generated.

  On the other hand, in the present invention, as shown in FIG. 7, the load support 82 is installed in the vicinity of the corner portion of the closing seal 75 installed around the openings 34a and 33b adjacent to the cooling medium opening 32a. . This load support 82 is similarly installed in the vicinity of the corner portion R of the closing seal 75 installed around the opening 33a adjacent to the cooling medium opening 32b (see FIG. 4). By providing such a load support 82, the problem of non-uniform load due to the displacement of the corner portion R of the sealing material is reduced. It should be noted that the load support 82 installed on the surface of each separator through which the same fluid flows (in this embodiment, the surface of the metal separator 18B through which the cooling medium flows) is aligned in the stacking direction when viewed in the cell stack section. It is preferable that it is installed in. This is because the non-uniformity of the tightening load applied to the sealing material can be alleviated throughout the stack.

  The load support 82 is preferably installed in the vicinity of the corner portion in the open portion of the connected partial release seal 80 among the closed seals 75 connected to the partial open seal 80. Specifically, as shown in FIG. 8, a straight line L1 extending the connecting portion 84 of the closing seal 75 and the partial opening seal 80, and a side of the closing seal 75 on the side close to the facing portion 31 (30) are extended. It is preferably installed in a region surrounded by a circle E having a radius r centering on the intersection C with the straight line L2. Here, r is the distance between the tip B and the point C on the side close to the facing portion 31 (30) of the sealing material connecting portion 84 on the straight line L1.

  By installing the load support 82 at this position, as described above, tightening in the vicinity of the corner portion of the closing seal 75 adjacent to the partial opening seal 80 without affecting the flow of the cooling medium to the separator flow path. It becomes possible to suppress the nonuniformity of the applied load. Further, the load support 82 has an effect of pressing the adhesive 50 inside the separator as shown in FIG. Therefore, conventionally, it is possible to suppress the peeling that occurs in the adhesive 50 in the metal separator for which a sufficient tightening load could not be applied, and to provide a fuel cell seal structure with good sealing performance. Become.

  The material of such a load support may be the same as that of the integrated sealing material 70, or may be another material such as the adhesive 50. Examples of the material of the load support include EPDM, NBR, fluorine rubber, silicone rubber, and natural rubber.

  Alternatively, the load support may have a shape integrated with the adjacent closing seal 75. This facilitates handling of the load support 82. For example, as shown in FIGS. 10 and 11, the load support 82 has a shape protruding from the corner portion of the closing seal 75 along the straight line L2 in FIG. 8 (FIG. 10), or a separator from the corner portion along the straight line L1. The shape protruding in the flow path direction (FIG. 11) can also be used. This makes it possible to simplify the installation process of the load support 82 in the assembly process.

  As another form, the load support 82 may be a protrusion provided on a corresponding surface portion of the separator 18. As a result, the installation process of the load support 82 can be eliminated. In this case, the height of the protrusion is designed to be approximately equal to the height of the sealing material 70 after compression.

  Furthermore, in addition to the installation of any of the load supports 82 described above, it is also possible to provide a dimple-like projection 90 along the interrupted portion (straight line L2) of the partial opening seal 80 as shown in FIG. is there. The positions, dimensions, and intervals of the protrusions 90 are designed so as not to adversely affect the load support 82 and the in-plane flux distribution of the cooling medium. For example, the protrusion may be a dimple provided at a corresponding position of the separator. Thereby, the uniformity of the tightening load of the seal part and the peeling prevention effect of the internal adhesive 50 can be further enhanced.

  When applying the present invention, there is no particular restriction on the shape of the corner portion R of the sealing material in the vicinity of the position where the load support is installed. Therefore, the corner portion R of the sealing material may have any shape, for example, a right angle shape or a curved shape.

  In the above-described example, the features of the present invention have been described by taking a fuel cell having a structure including a metal separator and a resin frame as an example. In the case of this structure, a gasket or the like is used as the sealing material on one side (front side) of the metal separator, and the sealing material on the back side of the metal separator becomes the adhesive 50. However, the present invention is not limited to this example, and can also be used in a fuel cell including other components such as a carbon separator.

  Moreover, although the said Example demonstrated the integrated sealing material 70 as an example, this invention is applicable also to the sealing material isolate | separated for every opening.

  Further, although the above embodiment has been described by taking the separator surface through which the cooling medium flows as an example, the load support 82 can be similarly installed on the separator surface through which the fuel gas or oxidant gas flows.

1 is a side view of a fuel cell stack according to an embodiment of the present invention. It is an expanded sectional view of the MEA part of the fuel cell of the Example of this invention. It is a disassembled perspective view of the single cell in the attitude | position which made the cell lamination direction the up-down direction of the fuel cell by this invention. It is a top view which shows the conventional seal structure arrangement | positioning. FIG. 5 is an enlarged view of a BB cross section of FIG. It is a part of lamination | stacking sectional drawing of the separator which has the conventional seal structure. It is an enlarged view of the sealing material arrangement | positioning by this invention. It is an enlarged view of sealing material arrangement | positioning by this invention, Comprising: It is a figure which shows the installation position of a load support body. FIG. 8 is an enlarged view of the FF cross section of FIG. It is a figure which shows another form of the load support body of this invention. It is a figure which shows another form of the load support body of this invention. It is a figure which shows another form of the seal structure of this invention.

Explanation of symbols

10 Fuel cell
11 Electrolyte membrane
12 Catalyst layer
13 Diffusion layer
14 Anode electrode
15 Catalyst layer
16 Diffusion layer
17 Cathode electrode
First member of 18A separator (metal separator)
18B Separator second member (metal separator)
18C 1st resin frame
18D second resin frame
19 modules
20 terminal
21 Insulator
22 End plate
23 Stack
24 Sintered member (tension plate)
25 bolts or nuts
26 Coolant flow path
27 Fuel gas flow path
28 Oxidant gas flow path
29 Fuel cell reaction section
30 Opposite part
31 Opposite part
32a Coolant opening on the inlet side
32b Cooling medium opening on outlet side
33a Fuel gas opening on the inlet side
33b Fuel gas opening on the outlet side
34a Oxidant gas opening on the inlet side
34b Oxidant gas opening at outlet
50 Adhesive
70 Integrated sealing material
75 Closure seal
80 Partially open seal
82 Load supports
84 Connecting part of closing seal and partial opening seal
90 Protrusions.

Claims (8)

An electrolyte assembly comprising an electrolyte and an electrode,
A flow path portion that circulates at least one of the plurality of types of fluid on the surface, and an opening formed through the surface to supply and discharge the corresponding fluid among the plurality of types of fluid to the flow path portion. A separator having a portion, and
On the surface of the separator, a sealing material disposed around the flow path and the opening,
A fuel cell comprising:
The seal material includes a partly open seal in which a part connected to the flow path part in the periphery of the opening part of at least one fluid is opened and a seal material is disposed in the other part, and all of the other fluid opening parts. A closure seal arranged to surround the periphery,
The fuel cell, wherein the connecting portion of the sealing material connected from the partially open seal to the sealing material of the flow path portion has a corner portion, and a load support is provided in the vicinity of the corner portion.   2. The fuel cell according to claim 1, wherein the sealing material has a structure in which a closing seal and a partial opening seal are integrated.   3. The fuel cell according to claim 1, wherein the load support is made of the same material as the seal material.   4. The fuel cell according to claim 1, wherein the load support is connected to a corner portion of the closing seal.   5. The fuel cell according to claim 4, wherein the load support is disposed in parallel to a flow of fluid flowing between the opening in which the partial opening seal is disposed and the flow path. .   The fuel cell according to claim 1, wherein the load support is a protrusion provided on the separator surface.   The fuel cell according to any one of the preceding claims, wherein a plurality of load supports are disposed in a portion connected to the flow path portion in the periphery of the opening portion where the partial release seal is disposed. .   The fuel cell according to claim 1, wherein the corner portion of the sealing material has a continuous curved shape.

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