Bonding Method for Fuel Cell Parts

Abstract

To provide a bonding method of fuel cell parts that spreads adhesive uniformly between a membrane electrode assembly and a frame member and suppresses leakage of the adhesive to the outer periphery.SOLUTION: A membrane electrode assembly 10, a frame member 20, and an adhesive layer 30 located between the two are provided. The frame member extends around the outer periphery of the membrane electrode assembly and has an outer diameter larger than the outer diameter of the membrane electrode assembly, the adhesive layer 30 is formed so as to go around the inner peripheral edge in a region from a region inside the outer peripheral edge of the frame member to a region inside the inner peripheral edge of the frame member. A pressing member 52 is moved toward the frame member, and the frame member is pressed by an outer periphery pressing portion 54 via an elastically deformed spring mechanism 53, the outer circumferential edge 22 of the frame member is elastically deformed into an inclined state by the pressure of the outer periphery pressing portion and brought into contact with the membrane electrode assembly, and the frame member is pressed by an inner periphery pressing portion 55 by further elastically deforming the spring mechanism.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for joining parts for a fuel cell, and more particularly to a method for joining a membrane electrode assembly of a fuel cell and a frame member for fixing the peripheral edge thereof.

Background Art

[0002] Conventionally, as a manufacturing apparatus for this type of fuel cell, it includes a membrane electrode assembly of a fuel cell, a frame member, and an adhesive for adhering the membrane electrode assembly and the frame member. An adhesive is applied in a circular shape along the outer peripheral edge of the membrane electrode assembly, and a frame member in the shape of a frame is overlaid thereon, and pressed and adhered with a pressing member having a pressing portion along the adhesive. Then, at the time of pressing, after pressing with the first pressing member, it is pressed with the second pressing member. Thereby, the adhesive in a wider range between the electrolyte membrane and the frame member can be moved to the exposed portion of the membrane electrode assembly, and the bubbles mixed in the adhesive disposed between the membrane electrode assembly and the frame member are effectively pushed out toward the end of the frame member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the manufacturing apparatus for a fuel cell having the above structure, when pressing the frame member against the membrane electrode assembly, there is a problem that the adhesive does not spread uniformly between the membrane electrode assembly and the frame member, and the adhesive strength is not uniform. Further, at the outer peripheral side end portion between the membrane electrode assembly and the frame member, there is a possibility that the adhesive leaks and spreads to the outside and protrudes. As a result, there is a problem that the adhesive force is not uniform.

[0005] The present invention has been made in view of such problems, and provides a method for joining fuel cell parts in which an adhesive spreads uniformly between a membrane electrode assembly and a frame member, and leakage of the adhesive to the outer periphery can be suppressed.

Means for Solving the Problems

[0006] In view of the above problems, a method for joining fuel cell parts according to the present invention includes a membrane electrode assembly and a frame member as parts of a fuel cell single cell, and an adhesive layer positioned between the membrane electrode assembly and the frame member. The method for joining fuel cell parts is to press and join the frame member toward the membrane electrode assembly with a pressing member. The frame member encircles along the outer peripheral portion of the membrane electrode assembly and has an outer shape that is slightly larger than the outer shape of the membrane electrode assembly. The adhesive layer is formed in a region from a portion inside the outer peripheral edge of the frame member by a predetermined width to a portion inside the inner peripheral edge of the frame member so as to encircle the inner peripheral edge. The pressing member includes an outer peripheral pressing portion that presses the outer peripheral edge of the frame member via a spring mechanism, and an inner peripheral pressing portion that presses the region where the adhesive layer is formed, inside the outer peripheral pressing portion. In the joining method, the pressing member is moved toward the frame member, and the frame member is pressed by the outer peripheral pressing portion via the elastically deformed spring mechanism. The outer peripheral edge of the frame member is elastically deformed into an inclined state by the pressing of the outer peripheral pressing portion and brought into contact with the membrane electrode assembly. By further elastically deforming the spring mechanism, the frame member is pressed by the inner peripheral pressing portion.

[0007] The method for joining parts for a fuel cell according to the present invention configured as described above presses, in a first step, an adhesive layer formed in a circular shape in a region from a site inside the outer peripheral edge of the membrane electrode assembly by a predetermined width to a site inside the inner peripheral edge of the frame member, with the frame member interposed therebetween, via a spring mechanism, by an outer peripheral pressing portion. As a result, the frame member is bent obliquely so that the outer peripheral side faces downward and comes into contact with the outer peripheral edge of the membrane electrode assembly, forming a filling space that closes the gap between the frame member and the membrane electrode assembly and allows the adhesive to enter. From this state, when the pressing member is moved in a second step, the inner peripheral pressing portion presses the adhesive layer with the frame member interposed therebetween. As a result, the pressed adhesive layer is extruded into the filling space. After that, when the frame member continues to be pressed, the frame member becomes flat, and since the gap on the outer peripheral side is closed, the space between the frame member and the membrane electrode assembly spreads uniformly toward the inner periphery, suppressing the leakage of the adhesive to the outer peripheral side. As a result, the frame member and the membrane electrode assembly can be uniformly adhered without leakage to the outer peripheral side.

Advantages of the Invention

[0008] According to the present invention, since the adhesive spreads uniformly between the membrane electrode assembly and the frame member, uniform adhesion is possible, and leakage of the adhesive to the outer periphery can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiment for Carrying Out the Invention

[0010] Hereinafter, an embodiment of a method for joining fuel cell parts according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view schematically showing an electrode assembly in which a membrane electrode assembly and a frame member, which are parts joined by the method for joining fuel cell parts according to this embodiment, are joined. FIG. 2 is a perspective view of the disassembled state of the membrane electrode assembly and the frame member shown in FIG. 1.

[0011] First, referring to FIGS. 1 and 2, an electrode assembly 1, which is a joined body for a fuel cell single cell joined by the method for joining fuel cell parts of this embodiment, will be described. The electrode assembly 1 for a fuel cell single cell includes a membrane electrode assembly (also referred to as MEA) 10, a frame member 20, and an adhesive layer 30 positioned between the membrane electrode assembly 10 and the frame member 20. The membrane electrode assembly 10 and the frame member 20 are parts of a fuel cell single cell and are joined to form the electrode assembly 1. In FIG. 1, the adhesive layer 30 is shown in a joined state and is indicated by a two-dot chain line. Also, FIGS. 1 and 2 are schematic illustrations, and the dimensions and the like of each part are not accurately represented.

[0012] The membrane electrode assembly 10 is rectangular in plan view and is used for a fuel cell that generates electricity by an electrochemical reaction between a fuel gas such as hydrogen and an oxidant gas such as oxygen. Although not shown in detail, the membrane electrode assembly 10 includes an anode electrode and a cathode electrode with a solid polymer electrolyte membrane interposed therebetween. Also, a gas diffusion layer (not shown) is formed outside the anode electrode and the cathode electrode as necessary.

[0013] The frame member 20 is made of a flexible thermoplastic resin, surrounds along the outer peripheral portion of the membrane electrode assembly 10, and has a rectangular outer shape that is slightly larger than the outer shape of the membrane electrode assembly 10. The frame member 20 is formed by an outer peripheral edge portion 22 with a rectangular opening 21 in the center and has a frame-like shape. The frame member 20 is formed in a flat plate shape, and all the outer peripheral edge portions 22 forming the four sides of the outer periphery are formed with the same width. The frame member 20 is basically a resin frame, and a multi-layer structure of multiple layers is preferable from the viewpoints of strength and elasticity. The frame member 20 is elastically deformable when pressed by an outer peripheral pressing portion 54 described later.

[0014] The adhesive layer 30 is formed by applying an adhesive for adhesively fixing the membrane electrode assembly 10 and the frame member 20 to the membrane electrode assembly 10. The thickness and width of the adhesive layer 30 are applied to a predetermined thickness in consideration of the adhesive strength, the step of the application region, etc. In this example, the adhesive layer 30 is formed on the upper surface (shown in the figure) of the membrane electrode assembly 10, and the application thickness t is applied to about 0.5 mm. Further, the adhesive layer 30 is formed in a circular shape in a region from a portion inside a predetermined width w1 from the outer peripheral end portion of the frame member 20 to a portion inside a predetermined width w2 from the inner peripheral edge portion of the opening 21 of the frame member 20. As the adhesive, an ultraviolet curable adhesive is used. The adhesive layer 30 does not deform when pressed by the outer peripheral pressing portion 54 described later with a pressure less than a predetermined pressure, maintains the application thickness t, and is compression deformable with a pressure equal to or higher than the predetermined pressure. Note that the adhesive layer 30 is not limited to an ultraviolet curable adhesive.

[0015] Next, a bonding device 50 for bonding the above-described membrane electrode assembly 10 and the frame member 20 with an adhesive layer 30 will be described with reference to FIG. 3. The bonding device 50 includes a pressing member 52 that is supported above a surface plate 51 fixed horizontally so as to be vertically movable via a vertical movement mechanism (not shown). The pressing member 52 presses and bonds the laminated membrane electrode assembly 10, adhesive layer 30, and frame member 20. The pressing member 52 includes an outer peripheral pressing portion 54 that presses the outer peripheral edge portion of the frame member 20 via a spring mechanism 53, and an inner peripheral pressing portion 55 that presses the region where the adhesive layer 30 is formed inside the outer peripheral pressing portion 54.

[0016] More specifically, the pressing member 52 has a rectangular shape in plan view and is formed in a rectangle equivalent to the frame member 20 or slightly smaller as shown in the figure. A stepped portion 52a is formed on the outer periphery of the central block portion of the pressing member 52, and the outer peripheral pressing portion 54 is provided in a state of being suspended by a compression spring constituting the spring mechanism 53 downward from this stepped portion. The outer peripheral pressing portion 54 has a frame shape with an opening in the center and is suspended by a plurality of compression springs so as to maintain a horizontal state in the suspended state.

[0017] The pressing member 52 includes an inner peripheral pressing portion 55 inside the outer peripheral pressing portion 54. The inner peripheral pressing portion 55 is formed as a protruding portion that protrudes circumferentially downward from the central block portion of the pressing member 52. Therefore, when looking at the pressing member 52 from below, the outer peripheral pressing portion 54 is positioned with a slight gap outside the inner peripheral pressing portion 55, and the outer peripheral pressing portion 54 is positioned below the inner peripheral pressing portion 55 in the suspended state. For this reason, when the frame member 20 is pressed by the pressing member 52, the outer peripheral pressing portion 54 is configured to come into contact with the frame member 20 first.

[0018] Here, with reference to FIG. 3, the planar positional relationship among the outer peripheral pressing portion 54, the inner peripheral pressing portion 55, the membrane electrode assembly 10, the frame member 20, and the adhesive layer 30 will be described. FIG. 3 shows the state before the frame member 20 is pressed by the pressing member 52. First, the adhesive layer 30 applied on the upper surface of the membrane electrode assembly 10 is formed in a circular shape in a region from a portion inside the outer peripheral end of the outer peripheral edge portion 22 of the frame member 20 by a predetermined width w1 to a portion inside the inner peripheral edge portion of the opening 21 of the frame member 20 by a predetermined width w2.

[0019] Therefore, the adhesive layer 30 with an applied thickness t on the upper surface of the membrane electrode assembly 10 is formed in a state of being shifted inward with respect to the frame-shaped frame body of the frame member 20. That is, the opening 21 and the outer peripheral edge portion 22 are formed such that the frame member 20 protrudes to the outer peripheral side with respect to the adhesive layer 30. Therefore, with respect to the adhesives layer 30 formed in a circular shape, the frame member 20 is positioned in a state of being shifted outward, and the outer peripheral edge portion 22 protrudes in a cantilever state above the adhesive layer 30.

[0020] The operation of the joining method of the fuel cell parts of the present embodiment configured as described above will be described below with reference to FIGS. 3 to 6. When joining the membrane electrode assembly 10 coated with the adhesive layer 30 and the frame member 20 to form the electrode assembly 1, the membrane electrode assembly 10 is placed on the horizontal surface of the surface plate 51 constituting the joining device 50 with the adhesive layer 30 surface facing up. Then, the frame member 20 is placed on the upper part of the membrane electrode assembly 10. At this time, it is placed so that the opening 21 and the outer peripheral edge portion 22 of the frame member 20 are evenly shifted outward with respect to the adhesive layer 30. In the set state of FIG. 3, the height between the upper surface of the surface plate 51 of the joining device 50 and the upper surface of the pressing member 52 is set to a height H1.

[0021] From this state, when the pressing member 52 is lowered as shown in FIG. 4, the outer peripheral pressing portion 54 presses the frame member 20 downward while compressing the spring mechanism 53. As the outer peripheral pressing portion 54 continues to press the frame member 20 and when the pressing member 52 reaches the height H2, since the outer peripheral edge side of the frame member 20 protrudes cantilevered from the outer peripheral end of the adhesive layer 30 and floats from the upper surface of the membrane electrode assembly 10, it elastically deforms into an inclined state so that the outer peripheral end side descends to press the frame member 20. Then, when the lower surface on the outer peripheral side of the frame member 20 abuts against the upper surface of the membrane electrode assembly 10, a filling space 31 having a triangular cross-sectional shape is formed in a side view.

[0022] This filling space 31 is a space formed between a distance w3 smaller than a predetermined width w1 of a portion where the adhesive layer 30 is not applied from the outer peripheral edge portion 22 of the frame member 20 and the coating thickness t of the adhesive layer 30. The outer peripheral edge portion 22 of the frame member 20 is pressed downward by the outer peripheral pressing portion 54, elastically deforms into an inclined state with the inner peripheral side riding on the adhesive layer 30, and a filling space 31 having a triangular cross-sectional shape is formed. That is, with the pressing force by which the outer peripheral pressing portion 54 elastically deforms and presses the spring mechanism 53, the adhesive layer 30 does not undergo compressive deformation and the coating thickness t is maintained.

[0023] After this, when the pressing member 52 is further lowered and the frame member 20 is pressed by the inner peripheral pressing portion 55 and the outer peripheral pressing portion 54, the compression spring of the spring mechanism 53 is further compressed and the movement in the direction of the frame member 20 is stopped. Then, when the inner peripheral pressing portion 55 is further lowered, the pressing force becomes equal to or greater than a predetermined value and the adhesive layer 30 is crushed. As shown in FIG. 5, when the pressing member 52 reaches the height H3, the adhesive layer 30 gradually enters the filling space 31, is stretched in the outer peripheral direction, and fills the filling space 31. Since the outer peripheral end of the filling space 31 is closed by the membrane electrode assembly 10 and the frame member 20, the entering adhesive 30a does not leak to the outer peripheral side.

[0024] When the pressing member 52 further descends to the height H4, as shown in FIG. 6, the outer peripheral pressing portion 54 compresses the spring mechanism 53, the inner peripheral pressing portion 55 presses the frame member 20, and compresses the adhesive 30a of the adhesive layer 30 filled in the filling space 31. The adhesive 30a is compressed by the inner peripheral pressing portion 55 to become flat, a flat portion 30b is formed, and the adhesive 30a filled in the filling space 31 is returned to the inner peripheral side and rises on the end face of the opening 21 of the frame member 20 to form a delta portion 30c. In this way, the frame member 20 can be uniformly adhered to the membrane electrode assembly 10 by the flat portion 30b, leakage of the adhesive to the outer peripheral side is suppressed, and the adhesion state is stabilized. Further, the frame member 20 and the membrane electrode assembly 10 are more strongly joined by the delta portion 30c formed by rising on the end face of the opening 21 of the frame member 20.

[0025] In this way, when the electrode assembly 1 in which the membrane electrode assembly 10 and the frame member 20 are joined by the adhesive layer 30 is removed from the joining device 50, it becomes as shown in FIG. 7. In the electrode assembly 1, the membrane electrode assembly 10 and the frame member 20 located below are uniformly joined by the flat adhesive layer 30, and a delta portion 30c that rises along the end face of the opening 21 of the frame member 20 is formed, so that they can be joined strongly. Further, leakage of the adhesive layer 30 to the outer peripheral side of the membrane electrode assembly 10 is suppressed.

[0026] As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the spirit of the present invention described in the claims. In the present invention, the configuration of one embodiment can be added to the configuration of another embodiment, the configuration of one embodiment can be replaced with that of another embodiment, or a part of the configuration of one embodiment can be deleted.

[0027] For example, although the joining device 50 that joins the membrane electrode assembly 10 and the frame member 20 with the adhesive layer 30 is shown as including the surface plate 51 and the pressing member 52, it may be configured with a mold including a lower mold and an upper mold, place the membrane electrode assembly 10 on the lower mold, and press the frame member with the upper mold for joining.

Explanation of Reference Numerals

[0028] 1: Electrode assembly (joined body), 10: Membrane electrode assembly (part), 20: Frame member (part), 21: Opening, 22: Outer peripheral edge portion, 30: Adhesive layer, 30b: Flat portion, 30c: Delta portion, 50: Joining device, 51: Surface plate, 52: Pressing member, 53: Spring mechanism, 54: Outer peripheral pressing portion, 55: Inner peripheral pressing portion, w1, w2: Predetermined width

Claims

【Claim 1】 A method for joining parts for a fuel cell, comprising a membrane electrode assembly and a frame member as parts of a fuel cell single cell, and an adhesive layer positioned between the membrane electrode assembly and the frame member, the method joining the frame member to the membrane electrode assembly by pressing the frame member toward the membrane electrode assembly with a pressing member, wherein the frame member surrounds along the outer peripheral portion of the membrane electrode assembly and has an outer shape that is slightly larger than the outer shape of the membrane electrode assembly, the adhesive layer is formed so as to surround the inner peripheral edge portion in a region from a portion inside a predetermined width from the outer peripheral edge portion of the frame member to a portion inside the inner peripheral edge portion of the frame member, the pressing member includes an outer peripheral pressing portion that presses the outer peripheral edge portion of the frame member via a spring mechanism, and an inner peripheral pressing portion that presses the region where the adhesive layer is formed, inside the outer peripheral pressing portion, in the joining method, the pressing member is moved toward the frame member, and the frame member is pressed by the outer peripheral pressing portion via the elastically deformed spring mechanism, the outer peripheral edge portion of the frame member is elastically deformed into an inclined state by the pressing of the outer peripheral pressing portion and brought into contact with the membrane electrode assembly, and the frame member is pressed by the inner peripheral pressing portion by further elastically deforming the spring mechanism, characterized in that it is a method for joining parts for a fuel cell.

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