JP7110946B2 - Dies for joining fuel cell single cells - Google Patents

Description

TECHNICAL FIELD The present invention relates to a joining die for manufacturing a fuel cell single cell, and more particularly to a joining die for joining a pair of separators to both surfaces of a membrane electrode assembly constituting a fuel cell single cell.

Conventionally, a pair of separators are placed on both sides of an electrode assembly in which a resin frame is provided around a membrane electrode assembly with an adhesive interposed therebetween, and the resin frame and each separator are joined by heat and pressure to form a single fuel cell. (see, for example, Patent Document 1).

For such joining, for example, a joining mold composed of first and second molds is generally used. At the time of joining, the electrode assembly having the separators arranged on both sides is placed between the first and second molds, and is hot-pressed by the first and second molds, so that the resin frame adheres to each separator. is welded to

JP 2017-126457 A

However, when the separator is joined to the electrode assembly by the first and second molds, a moment acts on the resin frame with respect to the membrane electrode assembly, and the edge of the opening formed in the resin frame is displaced by the membrane electrode assembly. I used to float up from Due to this floating, a gap is formed between the membrane electrode assembly and the resin frame, and the fuel gas or oxidant gas flowing to the membrane electrode assembly may leak from these gaps. In addition, there is a risk that the resin of the resin frame welded to the separator may flow excessively from the edge of the opening formed in the resin frame.

The present invention has been made in view of such problems. Provided is a joining mold for manufacturing a fuel cell single cell that can prevent the frame from rising and prevent the resin of the resin frame from excessively flowing out from the opening edge of the resin frame.

In order to achieve the above object, a bonding mold for manufacturing a single fuel cell according to the present invention includes a membrane electrode assembly having gas diffusion layers laminated on both sides, and and a resin frame adhered to the membrane electrode assembly, and a pair of separators are placed on both sides of the electrode assembly, and the pair of separators are hot-pressed to the resin frame. A bonding mold for manufacturing a fuel cell unit cell with separators bonded together, the bonding mold comprising a first mold that contacts one separator and a second mold that contacts the other separator. and the first mold includes a central receiving portion that receives a central region of the one separator that contacts the electrode assembly, and a central receiving portion that surrounds the central receiving portion and is welded to the resin frame. and an outer periphery receiving portion that receives the welded region of the one separator, and the second mold includes an inner mold that presses a central region of the other separator that contacts the electrode assembly, and a mold that surrounds the inner mold. and an outer mold configured to heat-press the welding region of the other separator to be welded to the resin frame, wherein the inner mold extends from the central region to the opening formed in the resin frame. an extending portion extending to a region on the outer peripheral side of the electrode assembly so as to press the resin frame through the other separator to a region on the outer peripheral side of the electrode assembly; is formed with a recess for preventing contact with the other separator at a portion facing the edge of the opening.

According to the joining mold for manufacturing the fuel cell single cell of the present invention, first, one separator, a membrane electrode assembly having gas diffusion layers laminated on both sides, and the other separator are laminated in order on the first mold. can do. At this time, one separator is placed so that the center region of one separator is received by the central receiving portion of the first mold, and the welding region to be welded to the resin frame is received by the outer peripheral receiving portion of the first mold. can be placed.

Next, the inner mold of the second mold presses (heats if necessary) the central region of the other separator, and then the outer mold of the second mold heat-presses the welding region of the other separator. , the pair of separators are welded together with the melted resin of the resin frame. At this time, even if the welding region of the other separator is pressurized by the outer mold of the second mold, the inner mold of the second mold separates the resin frame portion outside the opening edge from the electrode assembly. are pressing. Therefore, it is possible to reduce the moment acting on the resin frame with respect to the membrane electrode assembly due to the pressing force of the inner mold of the second mold. As a result, it is possible to prevent the adhesive portion between the resin frame and the membrane electrode assembly from peeling off from the edge of the opening of the resin frame.

In addition, a concave portion is formed in a portion of the extending portion that faces the edge of the opening of the resin frame, and this portion does not contact the other separator. Therefore, heating of the resin frame in the vicinity of the opening edge is suppressed, and the resin frame in the vicinity of the opening edge can be prevented from excessively flowing out from the opening edge into the flow path of the separator.

1 is a perspective view of a main part showing functions of an embodiment of a joining mold for manufacturing a single fuel cell according to the present invention; FIG. 2 is a schematic perspective view of an electrode assembly that constitutes the single fuel cell shown in FIG. 1. FIG. FIG. 2B is a cross-sectional view of a main part taken along line AA shown in FIG. 2A; 2 is a schematic perspective view of one separator that constitutes the single fuel cell shown in FIG. 1. FIG. FIG. 3B is a cross-sectional view of a main part taken along line BB shown in FIG. 3A; 2 is a schematic perspective view of the other separator that constitutes the single fuel cell shown in FIG. 1. FIG. FIG. 4B is a cross-sectional view of the essential parts along line CC shown in FIG. 4A; FIG. 4B is a cross-sectional view of a main part of a single cell in which the electrode assembly shown in FIG. 2B, one separator shown in FIG. 3B, and the other separator shown in FIG. 4B are joined; FIG. 6 is a cross-sectional view of a main part of a joining mold for manufacturing the unit cell shown in FIG. 5; FIG. 6B is a cross-sectional view of a main part of a state in which the single cell shown in FIG. 5 is joined with the joining mold shown in FIG. 6A;

An embodiment of a joining mold for manufacturing a single fuel cell according to the present invention will now be described in detail with reference to the drawings.

1. Fuel Battery Single Cell 1 First, the fuel battery single cell 1 will be described with reference to FIGS. 1 to 5. FIG. As shown in FIG. 1, a single fuel cell 1 includes an electrode assembly 10 and a pair of separators 20 and 30 bonded to both sides of the electrode assembly 10 so as to sandwich the electrode assembly 10 therebetween. A joining die 40 for joining these includes a first die 41 that contacts one separator 20 and a second die 45 that contacts the other separator 30 .

First, the electrode assembly 10 that constitutes the fuel cell single cell 1 will be described with reference to FIGS. 2A and 2B. The electrode assembly 10 includes a membrane electrode assembly 11 having gas diffusion layers 13a and 13b laminated on both sides thereof, and is fixed to the membrane electrode assembly 11 via an adhesive portion 15a so as to encircle the outer periphery of the membrane electrode assembly 11. and a resin frame 15.

As shown in FIG. 2A, the membrane electrode assembly 11 has a rectangular shape, and has an anode electrode bonded to one surface of a solid polymer electrolyte membrane and a cathode electrode bonded to the other surface. Furthermore, gas diffusion layers 13a and 13b are laminated on both sides of the membrane electrode assembly 11 . The central portion of the membrane electrode assembly 11 is rectangular, and gas diffusion layers 13a and 13b are formed on both sides of this portion to form a power generation region 14. As shown in FIG.

The resin frame 15 has a three-layer sheet structure in which a main layer made of a thermoplastic resin or a thermosetting resin, which serves as a frame body, and adhesive layers made of a thermoplastic resin are formed on both sides of the main layer, and the adhesive layer melts. By (softening) the resin frame is fused to the separators 20 and 30 . An opening is formed in the center of the resin frame 15 so as to surround the outer periphery of the membrane electrode assembly 11 . The resin frame 15 is fused to one surface of the membrane electrode assembly 11 . In FIG. 5, the membrane electrode assembly 11 and the resin frame 15 are adhered via an adhesive, and a part of the adhesive acts as an adhesive portion 15a from the opening edge 15b of the resin frame 15. It protrudes to the inner peripheral side along the opening edge 15b.

The resin frame 15 has openings 16a and 16b forming fuel gas flow paths, openings 17a and 17b forming oxidant gas flow paths, and an opening 18a forming a coolant flow path, on the outer peripheral side of the central opening. , 18b are formed. In this embodiment, the opening 16a on one side is the inlet for the fuel gas, and the opening 16b on the other side is the outlet for the fuel gas. The opening 17a on one side is an inlet for the oxidizing gas, and the opening 17b on the other side is an outlet for the oxidizing gas. Further, the central opening 18a on one side is an inlet for coolant such as cooling water, and the central opening 18b on the other side is an outlet for coolant. Flow paths for the fuel gas, oxidant gas, and coolant are partitioned by sealing materials (not shown) formed between the electrode assembly 10 and the pair of separators 20 and 30 .

A pair of separators 20, 30 joined to both sides of the electrode assembly 10 will now be described with reference to FIGS. 3A-4B. The separators 20 and 30 basically have the same configuration and are composed of an anode separator and a cathode separator.

The separators 20 and 30 are members molded from rectangular metal thin plates, and partition the membrane electrode assembly 11 between the fuel cell unit cells 1 in a stacked state, and separate the membrane electrode assembly from each other. It plays a role of collecting the electric power generated by 11. Separators 20, 30 are made of metal such as titanium, titanium alloy, or stainless steel.

The separators 20 and 30 have a plurality of grooves formed along the longitudinal direction on both sides of the central region corresponding to the power generation region 14 located in the center of the membrane electrode assembly 11 of the electrode assembly 10 . A fuel gas such as hydrogen gas or an oxidant gas such as air flows through the grooves on the side facing the membrane electrode assembly 11, and a coolant flows through the grooves on the side where the separators face each other in the stacked state. . As a result, the fuel gas is supplied from one side of the membrane electrode assembly 11 and the oxidant gas is supplied from the other side, so that the membrane electrode assembly 11 generates electricity.

As shown in FIG. 3A, one separator 20 has three openings formed on both sides in the longitudinal direction. These openings are formed in the same shape at positions corresponding to the openings formed on both sides of the electrode assembly 10 in the longitudinal direction. Specifically, the opening 25a on one side is an inlet for the fuel gas, and the opening 25b on the other side is an outlet for the fuel gas. The opening 26a on one side is an inlet for the oxidizing gas, and the opening 26b on the other side is an outlet for the oxidizing gas. Furthermore, the opening 27a on one side is an inlet for the coolant, and the opening 27b on the other side is an outlet for the coolant.

One separator 20 has a welding area 22 formed on the outer peripheral side so as to surround the central area 21 , and the resin of the resin frame 15 is welded in this welding area 22 . In this embodiment, as shown in FIG. 3B, a stepped region 23 is formed between the central region 21 and the welding region 22 . As shown in FIG. 5, the stepped region 23 is recessed on the side facing the electrode assembly 10. In this stepped region 23, the electrode assembly 10 (specifically, the gas diffusion layer 13a adhered to the resin frame 15) is recessed. part) is in a non-contact state.

As shown in FIG. 4A, the other separator 30 has three openings formed on both sides in the longitudinal direction. These openings are formed in the same shape at positions corresponding to the openings formed on both longitudinal sides of the electrode assembly 10 and one separator 20 . Specifically, the opening 35a on one side is an inlet for the fuel gas, and the opening 35b on the other side is an outlet for the fuel gas. The opening 36a on one side is an inlet for the oxidizing gas, and the opening 36b on the other side is an outlet for the oxidizing gas. Furthermore, the opening 37a on one side is an inlet for the coolant, and the opening 37b on the other side is an outlet for the coolant.

The upper separator 30 has a welding area 32 formed on the outer peripheral side so as to surround the central area 31 , and the resin of the resin frame 15 is welded in this welding area 32 . In this embodiment, as shown in FIG. 4B, a step region 33 is formed between the central region 31 and the welding region 32 . As shown in FIG. 5, the step region 33 is recessed on the side facing the electrode assembly 10, and in this step region 33, the electrode assembly 10 (specifically, the opening edge 15b of the resin frame 15 and its vicinity) is recessed. is in a non-contact state. The upper separator 30 contacts the electrode assembly 10 on the outer peripheral side of the separator 30 relative to the stepped region 33 and the inner peripheral side of the welding region 32 , specifically, in the region where the gasket 34 described later is arranged.

The other separator 30 has a gasket 34 on the surface opposite to the surface facing the electrode assembly 10 , that is, the outer surface of the fuel cell single cell 1 . The gasket 34 is arranged inside the welding region 32 so as to surround the central region 31 and the openings 37a and 37b. The gasket 34 has a flat portion 34a and a projecting portion 34b protruding from the flat portion 34a on the outer peripheral side of the flat portion 34a. When a fuel cell stack (not shown) is formed by stacking and fixing a large number of fuel cell single cells 1, the gasket 34 is deformed by pressing the projecting portion 34b to ensure sealing with the adjacent separator 20. be able to. This allows the coolant to flow between the separators 20 and 30 sealed by the gasket 34 .

The electrode assembly 10, in which the resin frame 15 is fixed to the membrane electrode assembly 11 shown in FIG. configured to That is, the gas diffusion layer 13a is in contact with the central region 21 of the separator 20, the resin frame 15 is in contact with the welding region 22, and the step region 23 is the portion of the gas diffusion layer 13a located at the opening edge 15b of the resin frame 15. away. Further, the gas diffusion layer 13b is in contact with the central region 31 of the separator 30, the upper surface of the resin frame 15 is in contact with the welding region 32, and the stepped region 33 is separated from the opening edge 15b of the resin frame 15.

2. Joining Mold 40 Next, the joining mold 40 for manufacturing the fuel cell single cell 1 configured as described above will be described with reference to FIGS. 6A and 6B. The bonding mold 40 of the present embodiment is a mold for manufacturing the single cell 1 by bonding the separators 20 and 30 to both surfaces of the electrode assembly 10. It has a mold 41 and a second mold 45 that is in contact with the upper part of the separator 30 of the single cell 1 . A first mold 41 positioned below is formed as a single mold and placed on a pedestal or the like (not shown). The upper second mold 45 is composed of two parts, an outer mold 45A and an inner mold 45B.

The first mold 41 is formed so as to surround a central receiving portion 41a that receives the central region 21 of one separator 20 that is in contact with the electrode assembly 10, and to surround the central receiving portion 41a, and is welded to the resin frame 15. and an outer periphery receiving portion 41b that receives the welded region 22 of the separator 20 below.

Specifically, the central receiving portion 41a is formed so as to support the central region 21 of the separator 20 in which a groove portion forming a flow path for circulating the fuel gas or the oxidant gas is formed, and the outer peripheral receiving portion 41b It is formed to receive a peripheral weld region 22 . A depressed portion 41c is further formed along the outer periphery of the central receiving portion 41a between the central receiving portion 41a and the outer peripheral receiving portion 41b.

A heating part 43 for joining the electrode assembly 10 and the separator 20 is built in the first mold 41 . As long as the heating unit 43 heats the first mold 41 , it may be of any type such as a steam type or an electric current type. The heating temperature is set so as to heat the separator 20 to a temperature at which the resin of the resin frame 15 of the electrode assembly 10 melts through the separator 20 .

The second mold 45 includes an inner mold 45B that presses the central region 31 of the separator 30 in contact with the electrode assembly 10, and a separator that is formed to surround the inner mold 45B and welded to the resin frame 15 of the electrode assembly 10. and an outer mold 45A for hot-pressing the welded region 32 of 30 . The outer mold 45A has an outer peripheral pressurizing portion 45d that contacts the welded region 32 of the separator 30, and the welded region 32 of the separator 30 is thermally pressed by the outer peripheral pressurizing portion 45d.

The inner die 45B has a central pressurizing portion 45c that contacts and pressurizes the central region 31 of the separator 30 . The central pressurizing part 45 c presses the resin frame 15 via the separator 30 from the central region 31 of the separator 30 to the region on the outer peripheral side of the electrode assembly 10 relative to the opening edge 15 b formed in the resin frame 15 . , an extension portion 45e extending to the outer peripheral region is formed. The extended portion 45e of the inner die 45B is formed with a recess 45g at a portion facing the opening edge 15b of the resin frame 15 to prevent contact with the other separator 30. As shown in FIG.

A clearance CL is formed on the outer periphery of the inner die 45B so that the inner die 45B positioned in the center of the second die 45 and the outer die 45A positioned on the outer periphery of the inner die 45B can move independently. ing. The inner die 45B and the outer die 45A are vertically movable by actuators (not shown), and are configured so that their respective pressing forces can be adjusted when joining the fuel cell single cells 1 together. In the bonding mold 40 of the present embodiment, the pressing force of the inner mold 45B that corrects warpage is set to be greater than the pressing force of the outer mold 45A that thermally presses the separator 30 .

A heating portion 47 for heating the electrode assembly 10 and the separator 30 is incorporated in the outer mold 45A of the second mold 45 . As long as the heating unit 47 heats (the outer mold 45A of) the second mold 45, the heating unit 47 may be of any type such as a steam type or an electric current type. The heating part 47 heats the outer peripheral pressure part 45 d and sets the heating temperature so as to heat the separator 30 to a temperature at which the resin of the resin frame 15 of the electrode assembly 10 is melted. In this embodiment, the heating portion 47 is built in the outer side 54A, but the heating portion may be built in the inner mold 45B, for example.

The first mold 41 has a flat bottom surface that is placed on a pedestal or the like. The contact surfaces of the first mold 41 with which the separator 20 contacts are the surface of the outer peripheral receiving portion 41b projecting so as to contact the welding region 22 of the separator 20 and the surface of the central receiving portion 41a contacting the central region 21. . The surface of the depressed portion 41c formed between the central receiving portion 41a and the outer peripheral receiving portion 41b is separated from the stepped region 23 of the separator 20 and is not in contact with the stepped region 23. As shown in FIG.

In the second mold 45, the surfaces to which the separator 30 is pressurized or heat-pressed are the surface of the outer peripheral pressurizing portion 45d of the outer mold 45A and the surface of the central pressurizing portion 45c of the inner mold 45B. The width of the portion 45d is about several millimeters (1 to 3 mm). A concave portion 45f recessed upward is formed between the outer peripheral pressing portion 45d and the central pressing portion 45c. The space formed by the depressed portion 45f prevents the gasket 34 from coming into contact with the outer mold 45A during bonding, and the depressed portion 45f absorbs heat transferred from the outer peripheral pressure portion 45d to the separator 30. Heat can be dissipated in the formed space.

3. Joining Method Using Joining Die 40 A joining method using the joining die 40 will be described below. One separator 20 is placed on a first mold 41 placed on a pedestal or the like. The central region 21 of the separator 20 is supported by the central receiving portion 41a, and the welded region 22 formed so as to surround the central receiving portion 41a is supported by the outer peripheral receiving portion 41b. In addition, the surface of the recessed portion 41 c formed by a step between the central receiving portion 41 a and the outer peripheral receiving portion 41 b is separated from the separator 20 .

Next, the electrode assembly 10 is placed on the separator 20 placed on the first mold 41 . The resin frame 15 fixed to the electrode assembly 10 with an adhesive is in contact with the welding region 22 of the separator 20 and supported by the outer periphery receiving portion 41 b of the first mold 41 . The gas diffusion layer 13a of the membrane electrode assembly 11 is in contact with the central region 21 of the separator 20, and the central region 21 is supported by the central receiving portion 41a. The surface of the depressed portion 41c is separated from the gas diffusion layer 13a and the portion of the separator 20 that faces it.

After that, the separator 30 is placed on the electrode assembly 10 . A central region 31 of the separator 30 contacts the gas diffusion layer 13 b formed on the membrane electrode assembly 11 of the electrode assembly 10 , and a welding region 32 of the separator 30 contacts the resin frame 15 .

Next, the second mold 45 is lowered by the actuator, and the central pressure portion 45c of the inner mold 45B presses the central region 31 of the separator 30. As shown in FIG. Next, with the center region 31 of the separator 30 being pressed, the actuator lowers the outer mold 45A, and a strong pressing force is applied while the outer mold 45A is in contact with the welded region 32 of the separator 30 .

In the first mold 41, the outer periphery receiving portion 41b is heated, and in the second mold 45, the outer mold 45A is heated. Therefore, in a state in which the warping of the central regions 21 and 31 of the separators 20 and 30 is corrected, the resin of the resin frame 15 melts in the welded regions 22 and 32 on the outer periphery, and the welded regions 22 and 32 of the separator 20 melt. , is joined to the resin frame 15 of the electrode assembly 10 .

When joining is performed by the joining die 40, the separator 20, the electrode assembly 10, and the separator 30 are first sandwiched between the central receiving portion 41a and the central pressing portion 45c of the inner mold 45B. Fixed. After that, the outer mold 45A is lowered to heat the welding regions 22 and 32 for joining, so that the separator 20, the electrode assembly 10, and the separator 30 are prevented from being dislocated and can be joined with high accuracy.

In this manner, the welded region 22 of the separator 20 and the separator 20 are bonded to the resin frame 15 of the electrode assembly 10 by the outer peripheral receiving portion 41b of the first mold 41 and the outer peripheral pressing portion 45d of the outer mold 45A of the second mold 45. The welding area 32 of 30 is sandwiched and these are welded by hot pressing. During this heat pressing, a counterclockwise moment M shown in FIG. 6B acts on the resin frame 15 . Specifically, the moment M acts in a direction in which the adhesive portion 15 a between the resin frame 15 and the membrane electrode assembly 11 is separated from the opening edge 15 b of the resin frame 15 . In particular, when the gasket 34 is provided on the outer periphery of the central region 31 of the separator 30, it is difficult to secure the welding width of the welding region 32 surrounding the outer periphery of the gasket 34, so the welding width becomes narrow, and such a moment M is generated. easy.

However, since the inner mold 45B of the second mold 45 is provided with the extending portion 45e extending outward from the opening edge 15b of the resin frame 15, the extending portion 45e is located outside the opening edge 15b. can be pressed against the resin frame 15 and the membrane electrode assembly 11 . As a result, the moment acting on the resin frame 15 with respect to the membrane electrode assembly 11 is reduced, and the resin frame 15 can be prevented from floating with respect to the membrane electrode assembly 11 . As a result, it is possible to prevent the adhesive portion 15 a that bonds the resin frame 15 and the membrane electrode assembly 11 from peeling off from the opening edge 15 b of the resin frame 15 .

By providing the recessed portion 45g in the extending portion 45e of the inner mold 45B, the contact area between the inner mold 45B and the separator 30 can be reduced. It is possible to suppress the transmission to the membrane electrode assembly 11 of the electrode assembly 10 via the electrode assembly 10 . As a result, deterioration in power generation performance of the single fuel cell 1 can be suppressed. Further, since the recessed portion 45g is formed in a portion of the extension portion 45e that faces the opening edge 15b of the resin frame 15, this portion does not come into contact with the other separator 30. As shown in FIG. Therefore, heating of the resin frame 15 in the vicinity of the opening edge 15b is suppressed, the resin frame in the vicinity of the opening edge 15b melts, excessively flows out from the opening edge 15b into the flow path of the other separator 30, and the other separator 30 melts. It is possible to prevent it from flowing into the channel.

Further, by providing a clearance CL between the outer mold 45A and the inner mold 45B, the heat of the outer mold 45A is hardly transmitted to the inner mold 45B, so that the membrane electrode assembly 11 is prevented from being heated to a high temperature. be able to.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the invention described in the claims. Changes can be made.

1: fuel cell single cell, 10: electrode assembly, 11: membrane electrode assembly, 13a, 13b: gas diffusion layer, 15: resin frame, 15b: opening edge, 20, 30: separator, 21, 31: central region, 22, 32: Welding region, 34: Gasket, 40: Joining mold, 41: First mold, 41a: Central receiving part, 41b: Peripheral receiving part, 43, 47: Heating part, 45: Second mold , 45A: outer mold, 45B: inner mold, 45c: central pressurizing part, 45d: outer peripheral pressurizing part, 45e: extension part, 45g: concave part

Claims (1)

On both sides of an electrode assembly comprising a membrane electrode assembly having gas diffusion layers laminated on both sides, and a resin frame adhered to the membrane electrode assembly so as to surround the outer periphery of the membrane electrode assembly, A bonding mold for manufacturing a fuel cell single cell in which the pair of separators are bonded to the resin frame by hot pressing the pair of separators in a state where the separators are arranged,
The joining mold includes a first mold that contacts one separator and a second mold that contacts the other separator,
The first mold includes a central receiving portion that receives a central region of the one separator that contacts the electrode assembly, and the one separator that is formed so as to surround the central receiving portion and is welded to the resin frame. and a peripheral receiving portion that receives the welding region of
The second mold includes an inner mold that presses a central region of the other separator that contacts the electrode assembly, and the other separator that is formed to surround the inner mold and is welded to the resin frame. and an outer mold that heat-presses the welded area,
The inner die presses the resin frame through the other separator from the central region to a region on the outer peripheral side of the electrode assembly relative to the edge of the opening formed in the resin frame. and a concave portion that prevents contact with the other separator is formed in the extending portion at a portion facing the opening edge. Joining mold.

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