JP7694471B2 - How to join fuel cell parts - Google Patents

Description

The present invention relates to a method for joining fuel cell parts, and in particular to a method for joining fuel cell parts that joins a membrane electrode assembly of a fuel cell to a frame member that fixes its peripheral portion.

Conventionally, this type of fuel cell manufacturing device includes a membrane electrode assembly of the fuel cell, a frame member, and an adhesive for bonding the membrane electrode assembly and the frame member. The adhesive is applied in a circular pattern around the outer periphery of the membrane electrode assembly, a frame-shaped frame member is placed on top of the adhesive, and the adhesive is pressed and bonded with a pressing member having a pressing portion that fits along the adhesive. When pressing, the first pressing member presses, and then the second pressing member presses. This allows a wider range of adhesive between the electrolyte membrane and the frame member to move to the exposed portion of the membrane electrode assembly, and air bubbles mixed in the adhesive between the membrane electrode assembly and the frame member are effectively pushed out toward the edge of the frame member.

JP 2021-89845 A

However, in the fuel cell manufacturing apparatus having the above structure, when the frame member is pressed against the membrane electrode assembly, the adhesive does not spread evenly between the membrane electrode assembly and the frame member, resulting in an uneven adhesive strength. In addition, at the outer peripheral end between the membrane electrode assembly and the frame member, the adhesive may leak out and overflow. As a result, there is a problem of uneven adhesive strength.

The present invention was made in consideration of these problems, and aims to provide a method for joining fuel cell parts that allows the adhesive to spread evenly between the membrane electrode assembly and the frame member, while preventing the adhesive from leaking out to the periphery.

In view of the above-mentioned problems, the method for joining fuel cell parts according to the present invention is a method for joining fuel cell parts, which comprises a membrane electrode assembly and a frame member as parts of a single fuel cell cell, and an adhesive layer located between the membrane electrode assembly and the frame member, and which presses the frame member against the membrane electrode assembly with a pressing member to join the parts, the frame member running along the outer periphery of the membrane electrode assembly and having an outer shape that is one size larger than the outer shape of the membrane electrode assembly, the adhesive layer running around the inner periphery in a region from a portion inside a predetermined width from the outer periphery of the frame member to a portion inside the inner periphery of the frame member, The pressing member is formed as follows: the pressing member has an outer pressing portion that presses the outer peripheral edge of the frame member via a spring mechanism, and an inner pressing portion that presses the area where the adhesive layer is formed, inside the outer pressing portion; and in the bonding method, the pressing member is moved toward the frame member, the outer pressing portion presses the frame member via the elastically deformed spring mechanism, the outer peripheral pressing portion elastically deforms the outer peripheral edge of the frame member into an inclined state and abuts against the membrane electrode assembly by pressing the outer peripheral pressing portion, and the spring mechanism is further elastically deformed to press the frame member with the inner pressing portion.

In the method for joining fuel cell parts of the present invention configured as described above, in the first stage, the adhesive layer formed in a circumferential shape in the region from a portion inside the outer peripheral edge of the membrane electrode assembly by a predetermined width to a portion inside the inner peripheral edge of the frame member is pressed by the outer peripheral pressing portion via a spring mechanism while sandwiching the frame member. As a result, the frame member is bent obliquely so that the outer peripheral side is downward and abuts against the outer peripheral edge of the membrane electrode assembly, blocking the gap between the frame member and the membrane electrode assembly and forming a filling space into which the adhesive enters. When the pressing member is moved from this state in the second stage, the inner peripheral pressing portion presses the adhesive layer while sandwiching the frame member. As a result, the pressed adhesive layer is pushed out into the filling space. After this, when the frame material is continued to be pressed, the frame member becomes flat, and since the gap on the outer peripheral side is blocked, the gap between the frame member and the membrane electrode assembly spreads uniformly toward the inner circumference, and leakage of the adhesive to the outer peripheral side is suppressed. As a result, the frame member and the membrane electrode assembly can be uniformly bonded without leakage to the outer peripheral side.

According to the present invention, the adhesive spreads evenly between the membrane electrode assembly and the frame member, enabling uniform adhesion and preventing the adhesive from leaking out to the periphery.

1 is a perspective view that shows a schematic view of an electrode assembly in which a membrane electrode assembly and a frame member are joined by one embodiment of a method for joining fuel cell parts according to the present invention. FIG. 2 is an exploded perspective view of the membrane electrode assembly and a frame member shown in FIG. 1. FIG. FIG. 3 is a schematic end view of an apparatus for joining the membrane electrode assembly and the frame member shown in FIGS. 1 and 2 . FIG. 4 is a schematic end view showing a post-process step of FIG. 3 . FIG. 5 is a schematic end view showing a post-process step of FIG. 4 . FIG. 6 is a schematic end view showing a process subsequent to that shown in FIG. 5 . 7 is a schematic end view showing a completed state of the electrode assembly in which the membrane electrode assembly and the frame member are joined in the step of FIG. 6.

Below, one embodiment of the method for joining fuel cell parts according to the present invention will be described in detail with reference to the drawings. Figure 1 is a perspective view showing a schematic diagram of an electrode assembly in which a membrane electrode assembly and a frame member, which are parts to be joined by the method for joining fuel cell parts according to this embodiment, are joined, and Figure 2 is a perspective view showing the membrane electrode assembly and the frame member shown in Figure 1 in an exploded state.

First, referring to Figures 1 and 2, an electrode assembly 1, which is an assembly for a single fuel cell, joined by the joining method for fuel cell parts of this embodiment, will be described. The electrode assembly 1 for a single fuel cell includes a membrane electrode assembly (also called MEA) 10, a frame member 20, and an adhesive layer 30 located 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 single fuel cell, and are joined together to form the electrode assembly 1. In Figure 1, the adhesive layer 30 is shown in a joined state by a two-dot chain line. Also, Figures 1 and 2 are schematic views, and the dimensions of each part are not shown accurately.

The membrane electrode assembly 10 has a rectangular shape in a plan view, and is used in a fuel cell that generates electricity through 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 sandwiching a solid polymer electrolyte membrane. In addition, gas diffusion layers (not shown) are formed on the outside of the anode electrode and the cathode electrode as necessary.

The frame member 20 is made of a flexible thermoplastic resin, runs around the outer periphery 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 in a frame shape with an outer periphery 22 that has a rectangular opening 21 in the center. The frame member 20 is formed in a flat plate shape, and the outer periphery 22 that forms the four sides of the periphery are all formed with the same width. The frame member 20 is basically a resin frame, and a multi-layer structure with multiple layers is preferable from the standpoint of strength and elasticity. The frame member 20 is elastically deformable when pressed by the outer periphery pressing part 54 described later.

The adhesive layer 30 is formed by applying an adhesive that bonds and fixes 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 taking into consideration the adhesive strength and the step of the application area. In this example, the adhesive layer 30 is formed on the upper surface of the membrane electrode assembly 10 as shown in the figure, and is applied to a coating thickness t of about 0.5 mm. The adhesive layer 30 is formed in a circumferential shape in an area from a portion inside the outer peripheral end of the frame member 20 by a predetermined width w1 to a portion inside the inner peripheral edge of the opening 21 of the frame member 20 by a predetermined width w2. An ultraviolet-curing adhesive is used as the adhesive. When pressed by the outer peripheral pressing portion 54 described later, the adhesive layer 30 does not deform below a predetermined pressing force, maintains the coating thickness t, and is compressively deformable above the predetermined pressing force. The adhesive layer 30 is not limited to an ultraviolet-curing adhesive.

Next, a bonding device 50 for bonding the membrane electrode assembly 10 and the frame member 20 with the adhesive layer 30 will be described with reference to FIG. 3. The bonding device 50 includes a pressing member 52 supported on the top of a horizontally fixed base plate 51 so as to be movable up and down via a vertical movement mechanism (not shown). The pressing member 52 presses and bonds the membrane electrode assembly 10, adhesive layer 30, and frame member 20, which are arranged in a stacked manner. The pressing member 52 includes an outer peripheral pressing portion 54 that presses the outer peripheral edge of the frame member 20 via a spring mechanism 53, and an inner peripheral pressing portion 55 that presses the area where the adhesive layer 30 is formed, inside the outer peripheral pressing portion 54.

More specifically, the pressing member 52 has a rectangular shape in a plan view, and is formed as a rectangle that is the same as the frame member 20 or slightly smaller as shown. A step portion 52a is formed on the outer periphery of the central block portion of the pressing member 52, and the outer periphery pressing portion 54 is provided below this step portion in a state in which it is suspended by compression springs that constitute the spring mechanism 53. The outer periphery pressing portion 54 is frame-shaped with an opening in the center, and is suspended by multiple compression springs so as to maintain a horizontal position when suspended.

The pressing member 52 has an inner pressing portion 55 inside the outer pressing portion 54. The inner pressing portion 55 is formed as a protrusion that protrudes downward from the central block portion of the pressing member 52 in a circular shape. Therefore, when the pressing member 52 is viewed from below, the outer pressing portion 54 is located outside the inner pressing portion 55 with a small gap, and the outer pressing portion 54 is located below the inner pressing portion 55 in a suspended state. Therefore, when the pressing member 52 presses the frame member 20, the outer pressing portion 54 is configured to abut against the frame member 20 first.

Now, referring to FIG. 3, the planar positional relationship between 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 to the upper surface of the membrane electrode assembly 10 is formed in a circular shape in the region from a portion inside the outer peripheral edge 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 of the opening 21 of the frame member 20 by a predetermined width w2.

Therefore, the adhesive layer 30 with a thickness t applied to the upper surface of the membrane electrode assembly 10 is formed in a state where it is shifted toward the inner periphery with respect to the frame-shaped frame of the frame member 20. In other words, the opening 21 and the outer periphery 22 are formed so that the frame member 20 protrudes toward the outer periphery with respect to the adhesive layer 30. Therefore, the frame member 20 is positioned in a state where it is shifted outward with respect to the adhesive layer 30 that is formed in a circumferential shape, and the outer periphery 22 protrudes in a cantilever manner above the adhesive layer 30.

The operation of the fuel cell part joining method of the present embodiment configured as described above will be described below with reference to Figures 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 with the adhesive layer 30 side facing up on the horizontal surface of the base plate 51 constituting the joining device 50. Then, the frame member 20 is placed on top of the membrane electrode assembly 10. At this time, the frame member 20 is placed so that the opening 21 and the outer peripheral edge 22 of the frame member 20 are evenly shifted outward relative to the adhesive layer 30. In the set state of Figure 3, the height between the top surface of the base plate 51 of the joining device 50 and the top surface of the pressing member 52 is set to height H1.

When the pressing member 52 is lowered from this state as shown in FIG. 4, the outer peripheral pressing portion 54 presses the frame member 20 downward while compressing the spring mechanism 53. When the outer peripheral pressing portion 54 continues to press the frame member 20 and the pressing member 52 reaches height H2, the outer peripheral edge side of the frame member 20 protrudes in a cantilever manner from the outer peripheral end of the adhesive layer 30 and is floating above the upper surface of the membrane electrode assembly 10, so that the outer peripheral end side elastically deforms to an obliquely inclined state so as to descend and presses the frame member 20. Then, when the lower surface of the outer peripheral side of the frame member 20 abuts against the upper surface of the membrane electrode assembly 10, a filling space 31 whose cross section is triangular in side view is formed.

This filling space 31 is a space formed between a distance w3, which is smaller than the predetermined width w1 from the outer peripheral edge 22 of the frame member 20 to the portion where the adhesive layer 30 is not applied, and the application thickness t of the adhesive layer 30. The outer peripheral edge 22 of the frame member 20 is pressed downward by the outer peripheral pressing portion 54, and elastically deforms and becomes inclined with the inner peripheral side resting on the adhesive layer 30, forming a filling space 31 with a triangular cross-sectional shape. In other words, the adhesive layer 30 is not compressed and deformed by the pressing force with which the outer peripheral pressing portion 54 elastically deforms and presses the spring mechanism 53, and the application thickness t is maintained.

After this, the pressing member 52 is further lowered, and the frame member 20 is pressed by the inner pressing portion 55 and the outer pressing portion 54, so that the compression spring of the spring mechanism 53 is further compressed and the movement toward the frame member 20 is stopped. Then, when the inner pressing portion 55 is further lowered, the pressing force exceeds a predetermined value and the adhesive layer 30 is crushed. As shown in FIG. 5, when the pressing member 52 reaches height H3, the adhesive layer 30 gradually enters the filling space 31 and is pressed and stretched in the outer circumferential direction to fill the filling space 31. The outer circumferential end of the filling space 31 is closed by the membrane electrode assembly 10 and the frame member 20, so that the entering adhesive 30a does not leak out to the outer circumferential side.

When the pressing member 52 is further lowered to a height H4, as shown in FIG. 6, the outer peripheral pressing portion 54 compresses the spring mechanism 53, and the inner peripheral pressing portion 55 presses the frame member 20, compressing the adhesive 30a of the adhesive layer 30 that fills the filling space 31. The adhesive 30a is compressed and flattened by the inner peripheral pressing portion 55, forming a flat portion 30b, 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 bonded to the membrane electrode assembly 10 by the flat portion 30b, and the leakage of the adhesive to the outer peripheral side is suppressed, stabilizing the bonding state. In addition, the delta portion 30c formed by rising on the end face of the opening 21 of the frame member 20 bonds the frame member 20 and the membrane electrode assembly 10 more strongly.

When the electrode assembly 1, in which the membrane electrode assembly 10 and the frame member 20 are thus joined by the adhesive layer 30, is removed from the joining device 50, it becomes as shown in FIG. 7. The electrode assembly 1 can be strongly joined because 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 edge face of the opening 21 of the frame member 20 is formed. In addition, the adhesive layer 30 is prevented from leaking out to the outer periphery of the membrane electrode assembly 10.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the spirit of the present invention described in the claims. The present invention allows the configuration of one embodiment to be added to the configuration of another embodiment, the configuration of one embodiment to be replaced with another embodiment, or part of the configuration of one embodiment to be deleted.

For example, the bonding device 50 that bonds the membrane electrode assembly 10 and the frame member 20 with the adhesive layer 30 has been shown as having a base plate 51 and a pressing member 52, but it may also be configured as a mold having a lower mold and an upper mold, in which the membrane electrode assembly 10 is placed on the lower mold and the frame member is pressed with the upper mold to bond them.

1: electrode assembly (joint), 10: membrane electrode joint (part), 20: frame member (part), 21: opening, 22: outer periphery, 30: adhesive layer, 30b: flat part, 30c: delta part, 50: joining device, 51: base plate, 52: pressing member, 53: spring mechanism, 54: outer periphery pressing part, 55: inner periphery pressing part, w1, w2: predetermined width

Claims (1)

A method for joining parts for a fuel cell, comprising: a membrane electrode assembly and a frame member as parts of a single fuel cell; and an adhesive layer located between the membrane electrode assembly and the frame member, the method comprising pressing the frame member against the membrane electrode assembly with a pressing member to join the membrane electrode assembly, the method comprising:
the frame member is configured to surround an outer periphery of the membrane electrode assembly and has an outer shape that is slightly larger than an outer shape of the membrane electrode assembly,
the adhesive layer is formed around the inner peripheral edge portion in a region from a portion on the inside of the outer peripheral edge portion of the frame member by a predetermined width to a portion on the inside of the inner peripheral edge portion of the frame member,
the pressing member includes an outer circumferential pressing portion that presses the outer circumferential edge portion of the frame member via a spring mechanism, and an inner circumferential pressing portion that is located inside the outer circumferential pressing portion and presses a region where the adhesive layer is formed,
In the bonding 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 pressing portion presses against the outer peripheral edge portion of the frame member, causing the outer peripheral edge portion of the frame member to elastically deform into an inclined state and come into contact with the membrane electrode assembly;
The method for joining parts for a fuel cell, further comprising the step of elastically deforming the spring mechanism to press the frame member with the inner peripheral pressing portion.

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