JP2008153019A - Manufacturing method for unit cell of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method for unit cell of fuel cell, capable of satisfactorily keeping electrical contact between a metal plate and a membrane-electrode assembly. <P>SOLUTION: The manufacturing method of the unit cell of the fuel cell, having a plate-like membrane-electrode assembly and first and second metal plates 5, arranged on each side of the membrane-electrode assembly and mechanically sealing the peripheral regions of these metal plates 5 via an insulating layer has at least a process in which the first metal plate, having an erected part in the peripheral region 5a; the membrane-electrode assembly, and the second metal plate 5 are set vertically, in this order; and the erected part of the peripheral region of the first metal plate is bent inward to be caulked for sealing, and thereafter, a process working the overall shape of the unit cell, from a plane shape to an arch shape. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a plate-like membrane / electrode assembly and first and second metal plates arranged on both sides of the membrane / electrode assembly, and the peripheral region of these metal plates has an insulating layer interposed therebetween. The present invention relates to a method of manufacturing a fuel cell that is mechanically sealed in a state where it is interposed in a fuel cell.

  As such a fuel battery cell, for example, one having a configuration disclosed in Patent Document 1 below is known. This fuel cell has a first metal plate and a second metal plate that function as a cathode plate and an anode plate on both sides of a plate-like membrane / electrode assembly, respectively, and the peripheral region of the metal plate is insulated. It is mechanically sealed with the layers in between. According to such a configuration, the entire cell can be formed in a thin plate shape, which can contribute to reduction in thickness and size. The fuel gas flow path is formed inside the metal plate.

  On the other hand, as a technique for manufacturing the thin fuel cell as described above, a manufacturing method and manufacturing equipment disclosed in Patent Document 2 below are known. According to this manufacturing process, the first metal plate is set in the vertical direction in the order of the first metal plate, the membrane / electrode assembly, and the second metal plate, each having a rising portion formed in the peripheral region. It has a step of mechanically sealing (caulking sealing) by tilting the bent part of the peripheral area inward, and it can surely manufacture a thin fuel cell while suppressing deformation of the member. Yes.

JP 2005-332744 A JP 2006-86041 A

  In the fuel cell having the above configuration, it is preferable to obtain as much electrical output as possible. In order to obtain a large output, it is necessary to improve the contact state between the first and second metal plates and the membrane / electrode assembly. This is because the contact resistance can be reduced and the output efficiency can be increased. Therefore, it is preferable that a thin fuel cell also has a structure that can satisfactorily make the contact state.

  This invention is made | formed in view of the said situation, The subject is providing the manufacturing method of the fuel cell which can hold | maintain the electrical-machine contact state of a metal plate and a membrane electrode assembly favorably.

In order to solve the above problems, a method for producing a fuel cell according to the present invention includes:
A plate-like membrane / electrode assembly and first and second metal plates disposed on both sides of the membrane / electrode assembly, and the peripheral region of these metal plates interpose an insulating layer. In a method for manufacturing a fuel cell that is mechanically sealed in a state,
In the state where the first metal plate having the rising portion formed in the peripheral region, the membrane / electrode assembly, and the second metal plate are set in the vertical direction, the rising portion of the peripheral region of the first metal plate is Tilting inward and mechanically sealing,
After this process, it has at least a process of processing the entire shape of the fuel cell from a planar shape to an arch shape.

  The operation and effect of the method for producing a fuel battery cell having such a configuration will be described. The fuel cell to be manufactured includes a plate-shaped membrane / electrode assembly and a pair of metal plates disposed on both sides thereof. In the processing step, the first metal plate (having a box shape) having a rising portion formed in the peripheral region, the membrane / electrode assembly, and the second metal plate are set in the vertical direction in this order. Then, the peripheral area is mechanically sealed by tilting the peripheral area of the first metal plate inward. In addition, an insulating layer is interposed in the peripheral region, and the first metal plate and the second metal plate are sealed in an insulated state. In this state, a planar fuel cell is manufactured. Furthermore, it has the process of processing the whole shape of a fuel cell from flat form to arch shape after this sealing process. As a result, the first and second metal plates and the membrane / electrode assembly are deformed in an arch shape, thereby improving the electrical contact state between the metal plate and the membrane / electrode assembly. As a result, it is possible to provide a method for manufacturing a fuel cell that can satisfactorily maintain the electrical contact state between the metal plate and the membrane / electrode assembly.

  In the present invention, the first metal plate functions as a cathode side metal plate in which many holes for taking in air are formed, and can be processed into an arch shape such that the surface of the first metal plate is convex. preferable.

  According to this structure, since the surface of the 1st metal plate in which the hole for taking in air was formed is processed in the arch shape so that it may become convex, it can be made the shape which is easy to take in air.

  In this invention, it is preferable that the notch is formed in the direction which cross | intersects the arch formation direction on the surface of the 1st metal plate. By forming such a cut, it becomes easy to process into an arch shape.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments of a fuel cell manufacturing method and manufacturing equipment according to the present invention will be described with reference to the drawings. First, the structure of the fuel cell to be manufactured will be described. FIG. 1 is an external perspective view of the fuel cell according to the present invention as viewed from the anode side, and FIG. 2 is an external perspective view of the fuel cell as viewed from the cathode side. FIG. 3 is an assembled perspective view showing an example of the fuel battery cell shown in FIGS. 1 and 2, and FIG. 4 is a longitudinal sectional view of the fuel battery cell shown in FIGS. FIG. 5 is a diagram showing the shape of the flow channel. FIG. 3 shows a state before processing into an arch shape.

  As shown in the drawings, the fuel battery cell of the present invention is disposed on a plate-shaped solid polymer electrolyte 1, a cathode-side electrode plate 2 disposed on one side of the solid polymer electrolyte 1, and on the other side. The anode side electrode plate 3 is provided. Further, the cathode side metal plate 4 (corresponding to the first metal plate) is arranged outside the cathode side electrode plate 2, and the anode side metal plate 5 (corresponding to the second metal plate) is arranged outside the anode side electrode plate 3. Is done.

  The peripheral regions 4a and 5a of the metal plates 4 and 5 are sealed by caulking (corresponding to press bending) after the solid polymer electrolyte 1 and the electrode plates 2 and 3 are accommodated. For convenience of explanation, regions other than the peripheral regions 4a and 5a of the metal plates 4 and 5 are referred to as central regions 4b and 5b.

  Moreover, the fuel cell is formed in a thin plate shape in an assembled state, and has a substantially rectangular shape. Furthermore, the overall shape of the fuel cell is not a flat shape but an arch shape. The direction in which the arch is formed is the short side direction, and the arch shape is such that the surface of the cathode side metal plate 4 is convex. Therefore, the surface of the anode side metal plate 5 is concave. By making the cathode side metal plate 4 side convex, air can be easily taken in.

  The solid polymer electrolyte 1 may be any solid polymer membrane battery as long as it is used in conventional solid polymer membrane batteries. From the viewpoint of chemical stability and conductivity, a perfluorocarbon having a sulfonic acid group which is a super strong acid. A cation exchange membrane made of a polymer is preferably used. Nafion (registered trademark) is preferably used as such a cation exchange membrane. In addition, for example, a porous film made of a fluororesin such as polytetrafluoroethylene impregnated with the above Nafion or other ion conductive material, a porous film made of a polyolefin resin such as polyethylene or polypropylene, or a non-woven fabric. A material carrying Nafion or another ion conductive material may be used.

  The thinner the solid polymer electrolyte 1 is, the more effective it is to make the whole thinner. However, in consideration of ion conduction function, strength, handling property, etc., 10 to 300 μm can be used, but 25 to 50 μm is preferable. .

  The electrode plates 2 and 3 can function as a gas diffusion layer, and can supply and discharge fuel gas, oxidizing gas, and water vapor, and at the same time can exhibit a current collecting function. As the electrode plates 2 and 3, the same or different ones can be used, and it is preferable to support a catalyst having an electrode catalytic action on the base material. The catalyst is preferably supported at least on the inner surfaces 2 b and 3 b in contact with the solid polymer electrolyte 1.

  As the electrode base material, for example, conductive carbon materials such as carbon paper, fibrous carbon such as carbon fiber nonwoven fabric, and aggregates of conductive polymer fibers can be used. In general, the electrode plates 2 and 3 are prepared by adding a water-repellent substance such as a fluororesin to such a conductive porous material. When the catalyst is supported, a catalyst such as platinum fine particles and fluorine It is formed by mixing a water-repellent substance such as a resin, mixing it with a solvent to form a paste or ink, and then applying this to one side of an electrode substrate that should face the solid polymer electrolyte membrane. The

  In general, the electrode plates 2 and 3 and the solid polymer electrolyte 1 are designed according to the reducing gas and the oxidizing gas supplied to the fuel cell. In the present invention, it is preferable to use air as the oxidizing gas and hydrogen gas as the reducing gas. In addition, methanol, dimethyl ether, or the like can be used instead of the reducing gas.

  For example, when hydrogen gas and air are used, the cathode-side electrode plate 2 on the side where air is naturally supplied causes a reaction between oxygen and hydrogen ions, so that water is generated. Is preferred. In particular, under the operating conditions of low operating temperature, high current density, and high gas utilization rate, the electrode porous body is likely to be clogged (flooded) due to the condensation of water vapor, particularly at the air electrode where water is generated. Therefore, in order to obtain stable characteristics of the fuel cell over a long period of time, it is effective to ensure the water repellency of the electrode so that the flooding phenomenon does not occur.

  As the catalyst, at least one metal selected from platinum, palladium, ruthenium, rhodium, silver, nickel, iron, copper, cobalt and molybdenum, or an oxide thereof can be used. A supported one can also be used.

  The thickness of the electrode plates 2 and 3 is more effective for reducing the overall thickness as the thickness is reduced, but is preferably 50 to 500 μm in view of electrode reaction, strength, handling properties, and the like. The electrode plates 2 and 3 and the solid polymer electrolyte 1 may be laminated and integrated in advance by adhesion, fusion, or the like, or may simply be arranged in a stacked manner. Such a laminated body can also be obtained as a membrane electrode assembly 10 (Mebrane Electrode Assembly: MEA), and this may be used.

  A cathode side metal plate 4 is disposed on the surface of the cathode side electrode plate 2, and an anode side metal plate 5 is disposed on the surface of the anode side electrode plate 3. The anode side metal plate 5 is provided with a fuel inlet 5c and a discharge port 5d, and in the present embodiment, the anode side metal plate 5 is provided with a flow channel 9 (see FIG. 5).

  The cathode side metal plate 4 is provided with a large number of opening holes 4c for supplying oxygen in the air. As long as the cathode side electrode plate 2 can be exposed, the number, shape, size, formation position, and the like of the opening holes 4c may be any. However, in consideration of the supply efficiency of oxygen in the air and the current collection effect from the cathode side electrode plate 2, the area of the opening 4c is preferably 10 to 50% of the area of the cathode side electrode plate 2, In particular, 20 to 40% is preferable. As for the opening hole 4c of the cathode side metal plate 4, you may provide a some circular hole, a slit, etc. regularly or randomly, or may provide an opening part with a metal mesh, for example.

  As the metal plates 4 and 5, any metal can be used as long as it does not adversely affect the electrode reaction, and examples thereof include stainless steel plates, nickel, copper, and copper alloys. However, from the viewpoint of elongation, weight, elastic modulus, strength, corrosion resistance, press workability, etching workability and the like, a stainless steel plate, nickel and the like are preferable.

  The channel groove 9 provided in the anode side metal plate 5 may have any planar shape or cross-sectional shape as long as a channel for hydrogen gas or the like can be formed by contact with the electrode plate 3. In the present embodiment, the inlet 5c and the outlet 5d are connected by a channel groove 9, and the channel groove 9 is formed in a zigzag shape that is periodically folded along the width direction of the metal plate 5. Yes. The flow channel groove 9 is composed of a wide horizontal groove 9a and a narrow vertical groove 9b, and the horizontal groove 9a and the horizontal groove 9a on both sides in the width direction are connected by three vertical grooves 9b. Even if one of the longitudinal grooves 9b is blocked for some reason, the remaining groove 9b prevents the channel groove 9 from being completely blocked. In consideration of the channel density, the stacking density at the time of stacking the fuel cells, the flexibility, etc., various forms of the channel grooves 9 can be adopted, and the present invention is not limited to the configuration shown in FIG.

  A part of the channel groove 9 of the metal plate 5 may be formed on the outer surface of the electrode plate 3. As a method of forming the flow channel groove on the outer surface of the electrode plate 3, a mechanical method such as a hot press or cutting may be used. However, it is preferable to perform groove processing by laser irradiation in order to suitably perform fine processing. From the viewpoint of performing laser irradiation, the base material for the electrode plates 2 and 3 is preferably an aggregate of fibrous carbon.

  One or a plurality of inlets 5c and outlets 5d communicating with the channel groove 9 of the metal plate 5 can be formed. In addition, although the thickness of the metal plates 4 and 5 is more effective for reducing the overall thickness as the thickness is reduced, 0.1 to 1 mm is preferable in consideration of strength, elongation, weight, elastic modulus, handling property, and the like.

  As a method of forming the flow path groove 9 in the metal plate 5, it can be formed by performing press working (stamping) on the metal plate. That is, by performing the punching process on the metal plate 5 shown in FIG. 3 from the back side, the flow channel 9 can be formed on the back side of the metal plate 5 as shown in FIGS. Since the flow channel 9 is formed by stamping, the same shape as the flow channel 9 appears on the surface side of the metal plate 5 as shown in FIG. The cross-sectional shape of the channel groove 9 is preferably substantially square, substantially trapezoidal, substantially semicircular, V-shaped or the like.

  The formation of the opening hole 4c in the metal plate 4 and the formation of the injection port 5c and the discharge port 5d in the metal plate 5 are also performed using press working. Further, the metal plates 4 and 5 are similarly formed with recesses in the central regions 4b and 5b by using press working (stamping). As shown in FIG. 4, the concave portion is a concave portion for accommodating the electrode plates 2 and 3 constituting the membrane / electrode assembly 10. Therefore, the area of the recess is processed according to the size of the electrode plates 2 and 3 to be accommodated.

  In the present invention, the peripheral regions 4a and 5a of the metal plates 4 and 5 are sealed by caulking in an electrically insulated state (an example of mechanical sealing). Electrical insulation is performed using an insulating sheet (corresponding to an insulating layer), but can also be performed by interposing the peripheral edge 1a of the solid polymer electrolyte 1.

  On the cathode side metal plate 4, a ring-shaped (frame-shaped) insulating sheet 11 is disposed in the peripheral region 4a as shown in FIG. The outer edge of the insulating sheet 11 is set to be approximately the same size as the edge of the metal plate 4, and the inner edge is a region where many opening holes 4 c are formed (or a size slightly larger than the size of the electrode plate 2). Is set to a slightly larger size.

  As shown in FIG. 1, ring-shaped (frame-shaped) insulating sheets 12 are also disposed on the front and back surfaces of the peripheral region 5 a on the anode side metal plate 5. The sizes of the insulating sheets 12 on both the front and back surfaces are the same. The outer edge of the insulating sheet 12 is set to approximately the same size as the edge of the metal plate 5, and the inner edge is set to a size slightly larger than the electrode plate 3.

  The solid polymer electrolyte 1 is slightly larger than the size of the electrode plates 2 and 3, and as shown in FIG. 4, the peripheral region 1 a exposed from the electrode plates 2 and 3 has insulating sheets 11 and 12. It is assembled so that it may be pinched by.

  That is, in the present invention, when caulking, the peripheral region 1a of the solid polymer electrolyte 1 in the region outside the electrode plates 2 and 3 is sandwiched between the peripheral regions 4a and 5a via the insulating sheets 11 and 12. State. According to such a structure, inflow of gas or the like from one of the electrode plates 2 and 3 to the other can be effectively prevented. Moreover, the insulating sheet 12 is provided also on the surface side of the metal plate 5, and can be sealed in a state in which the insulating performance is ensured when the crimping is performed.

  As the insulating sheets 11 and 12, a sheet-like resin, rubber, thermoplastic elastomer, ceramics, or the like can be used, but a resin, rubber, thermoplastic elastomer, or the like is preferable in order to improve sealing performance. Before processing the metal plates 4 and 5 into a predetermined shape, the insulating sheets 11 and 12 are attached to the metal plates 4 and 5 in advance, or directly or via an adhesive. I can leave. This point will be described later.

  As the caulking structure, the structure shown in FIG. 4 is preferable from the viewpoint of sealing performance, ease of manufacture, thickness, and the like. That is, the peripheral region 4a of one cathode side metal plate 4 is made larger than the peripheral region 5a of the other anode side metal plate 5, and the peripheral regions 4a of the cathode side metal plate 4 are interposed with the insulating sheets 11 and 12 interposed therebetween. A caulking structure is preferable in which the metal plate is folded so as to sandwich the peripheral region 5 a of the anode side metal plate 5. A manufacturing method and manufacturing equipment for performing such caulking sealing will be described in detail later.

  When configuring a fuel cell, one or a plurality of fuel cells as shown in FIGS. 1 and 2 can be used, but the solid polymer electrolyte 1, a pair of electrode plates 2, 3, and a pair of metal plates It is also possible to form unit cells with 4 and 5 and to stack a plurality of unit cells or to arrange them on the same surface. By doing so, it is possible to provide a high-power fuel cell without the need to apply a certain pressure to the cell parts by mutually coupling with the fastening parts of the bolts and nuts.

  When used as a fuel cell, it is possible to join a fuel supply pipe directly to the fuel inlet 5c and outlet 5d of the metal plate 5, but in making the fuel cell thinner, It is preferable to provide a joint mechanism having a small thickness and a pipe parallel to the surface of the metal plate 5.

  In FIG. 1, a joint booth (metal pin) 5 e is attached to the injection plate 5 c with respect to the metal plate 5. This attachment can be performed by caulking or press fitting. The metal pipe 13 can be press-fitted and attached to the pin 5e. A gas supply flow path can be formed by further inserting the resin pipe 14 into the metal pipe 13 (see FIG. 4). The same configuration is adopted for the outlet 5d.

  The metal plates 4 and 5 and the solid polymer electrolyte 1 which are members constituting the fuel battery cell are formed in a rectangular shape, but four corners thereof are formed in an R shape. By attaching R to the four corners, it is easy to perform the caulking sealing process described later.

  As described above, since the entire fuel cell is formed in an arch shape, the electrical contact between the metal plates 4 and 5 and the membrane / electrode assembly 10 can be favorably maintained. If the metal plates 4 and 5 and the membrane / electrode assembly 10 are brought into contact in a planar state, there is a possibility that a region that is not in partial contact may be formed, but by bending them into an arch shape, The contact pressure can be increased while increasing the contact area. Thereby, contact resistance can be reduced and an electrical output can be taken out efficiently.

<Manufacturing process of fuel cell>
Next, the manufacturing process and manufacturing equipment of the fuel battery cell described in FIGS. 1 to 5 will be described. FIG. 6 is a diagram showing an outline of the manufacturing process of the fuel cell. As shown in FIG. 6, the process is divided into a process for manufacturing the cathode-side metal plate 4, a process for manufacturing the anode-side metal plate 5, and a process for manufacturing the membrane / electrode assembly 10. After the electrode assembly 1 is manufactured, a process of assembling a fuel cell using these is performed.

  First, the structure of the progressive die equipment for manufacturing the cathode side metal plate 4 and the anode side metal plate 5 will be described. FIG. 7 is a conceptual diagram showing the configuration of the progressive die equipment. This progressive metal mold equipment can process both the cathode side metal plate 4 and the anode side metal plate 5, and therefore, seven molds are arranged along the conveyance path.

  As a raw material for processing the metal plates 4 and 5, a metal roll obtained by winding a long metal plate having a predetermined width around a roll is used. A long metal plate is pulled out from the metal roll and sent to a progressive mold facility, and necessary processing is performed. As the metal plates 4 and 5, long metal plates having the same width are used, but the metal plate 4 having an insulating sheet 11 attached to one side in advance is used, and the metal plate 5 is previously provided. A sheet having an insulating sheet 12 attached on both sides is used.

  The seven molds shown in FIG. 7 are arranged at predetermined intervals, and are used only when the anode side metal plate 5 is manufactured (first, second, third and sixth molds), and the cathode side metal. It has a mold (fourth and seventh molds) used only when the plate 4 is manufactured and a mold (fifth mold) that can be used in common for both the metal plates 4 and 5. Therefore, when the cathode side metal plate 4 is manufactured, the first, second, third, and sixth molds are controlled to be inoperative, and when the anode side metal plate 5 is manufactured, the fourth and seventh molds are used. A mold control unit is provided for controlling so as to be inactive.

  If comprised as mentioned above, since it is not necessary to provide a separate progressive metal mold | die equipment in the cathode side metal plate 4 and the anode side metal plate 5, an installation cost can be made cheap.

  Next, specific processing contents will be described. FIG. 8 is a plan view showing a state in which the cathode side metal plate 4 is processed by the progressive die equipment, and FIG. 9 is a plan view showing a state in which the anode side metal plate 5 is processed by the progressive die equipment. is there. FIG. 10 is a cross-sectional view showing a state in which the cathode side metal plate 4 is processed by the progressive die equipment, and FIG. 11 is a cross sectional view showing a state in which the anode side metal plate 5 is processed by the progressive die equipment. is there.

  First, a process of manufacturing the cathode side metal plate 4 will be specifically described. In FIG. 8, the long metal plate 50 drawn out from the metal roll has a predetermined width, and positioning holes 50a are formed in advance in both sides in the width direction at predetermined intervals. The insulating sheet 11 is also attached in advance at predetermined intervals. When affixing the insulating sheet 11, it can be affixed with the positioning hole 50a as a reference. The long metal plate 50 is conveyed from the left side to the right side in FIG.

  As shown in FIG. 8, first, a large number of holes 4c are formed by press drilling (S1). The cross-sectional shape at this stage is shown in FIG. This is done with a fourth mold. Next, a recess 4g punching process for accommodating the electrode plate 2 is performed (S2). The cross-sectional shape at this stage is shown in FIG. This is done with a fifth mold. Next, processing for punching out the outer shape of the metal plate 4 is performed (S3). The cross-sectional shape at this stage is shown in FIG. This is done with a seventh mold. The length after punching is indicated by L2.

  As the movement of the long metal plate 50, when the metal plate 50 moves intermittently with respect to the conveyance direction and a predetermined processing is performed by the mold, the long metal plate 50 is conveyed by a predetermined interval where the molds are arranged. As the operation of the mold, the processing of S1, S2, and S3 shown in FIG. 8 is performed simultaneously. That is, the processing progresses toward the downstream side in the transport direction. This is the same when the anode side metal plate 5 is processed.

  Next, the process of manufacturing the anode side metal plate 5 will be specifically described. In FIG. 9, a long metal plate 51 drawn out from a metal roll has a predetermined width, and positioning holes 51a are formed in advance in both sides in the width direction at predetermined intervals. The insulating sheet 12 is also attached to both the front and back surfaces at predetermined intervals. When the insulating sheet 12 is pasted, it can be pasted using the positioning hole 51a as a reference.

  As shown in FIG. 9, first, the punching process (first stage) of the flow channel groove 9 is performed (S11). This is done by the first mold. In this first stage, the channel groove 9 is not completely formed, and the groove depth is shallow. Next, the second stage punching process of the flow channel groove 9 is performed (S12). Thereby, the process of the flow-path groove | channel 9 is completed. The cross-sectional shape at this stage is shown in FIG. Next, press punching for forming holes (injection port 5c and discharge port 5d) for attaching the booth is performed (S13). This is done with a third mold.

  Next, a recess 5g is formed to accommodate the electrode plate 3 (S14). The cross-sectional shape at this stage is shown in FIG. This is done with a fifth mold. Next, processing for punching out the outer shape of the metal plate 5 is performed (S15). The cross-sectional shape at this stage is shown in FIG. This is done with a sixth mold. The length after punching is indicated by L1.

  As shown in FIG. 7, after punching out the outer shape of the anode side metal plate 5, a process for attaching a booth as shown in FIG. 4B is performed. The booth 5e can be connected to the inlet 5c and the outlet 5d by caulking.

  Further, after the outer shape of the cathode side metal plate 4 is punched, a drawing process for bending the peripheral region 4a 90 ° inward as shown in FIG. 12 is performed. FIG. 12B shows a perspective view after the drawing process, and a standing bent portion is formed on the entire periphery of the peripheral region 4a. By forming such a standing bent portion, it is possible to facilitate the caulking sealing process. The angle of the rising portion does not have to be exactly 90 °, and there is no problem if it is 90 ° ± 5 °.

<Mold configuration>
FIG. 13 is an external perspective view showing the mold equipment used in the assembly process of the fuel cell. FIG. 14 is a conceptual diagram showing a cross-sectional configuration of a mold. This basic structure of the mold can be applied to any mold used in the assembly process of the fuel cell described below. Although the mold shape may vary depending on the processing content, the basic mold configuration can be the structure shown in FIGS.

  The mold equipment includes a fixed unit 20 and a movable unit 30. The fixed side unit 20 includes a first lower mold 21 and a second lower mold 22 as molds. The first lower mold 21 is provided with a coil spring 23 as an urging mechanism, and acts to urge the first lower mold 21 upward. The first lower mold 21 presses the central region 4b of the cathode side metal plate 4 of the fuel cell. The second lower mold 22 is disposed so as to surround the first lower mold 21, and performs press working on the peripheral region 4 a of the metal plate 4. The second lower mold 22 is formed in a substantially rectangular annular shape in plan view. The second lower mold 22 includes a mechanism (corresponding to the first adjustment mechanism 24) that can be adjusted in the vertical direction. For example, the adjustment mechanism 24 can be configured by a mechanism using bolts and nuts. The first adjustment mechanism 24 can adjust the relative height relationship between the upper surface of the first lower mold 21 and the upper surface of the second lower mold 22. Specifically, the first lower mold 21 located in the central area is in a position recessed from the second lower mold 22 located in the peripheral area, and the protrusion amount h1 of the second lower mold 22 relative to the first lower mold 21 is set. Can be adjusted.

  The second lower mold 22 is formed with a hole 22a for inserting a guide shaft for guiding the second upper mold in the vertical direction.

  The movable unit 30 includes a first upper mold 31 and a second upper mold 32 as molds. The second upper mold 32 is provided with a coil spring 33 as an urging mechanism, and acts to urge the second upper mold 32 downward. The first upper mold 31 presses the central region 5b of the anode side metal plate 5 of the fuel cell. The second upper mold 32 is disposed so as to surround the first upper mold 31, and presses the peripheral area 5 a of the metal plate 5. The second upper mold 32 is formed in a substantially rectangular annular shape in plan view. The second upper mold 32 includes a mechanism (corresponding to the second adjustment mechanism 34) that can be adjusted in the vertical direction. As the adjustment mechanism 34, it can be comprised by the mechanism using a volt | bolt nut, for example. The relative height relationship between the lower surface of the first upper mold 31 and the lower surface of the second upper mold 32 can be adjusted by the second adjustment mechanism 34. Specifically, the protrusion amount h2 of the second upper mold 32 relative to the first upper mold 31 can be adjusted. By providing the adjusting mechanisms 24 and 34 as described above, an appropriate pressing force can be applied in press working.

  The second upper mold 32 is formed with a hole 32a for inserting a guide shaft for guiding the second upper mold 32 in the vertical direction.

  As shown in FIG. 14, pressing can be performed by operating the operation unit 40. In other words, the movable unit 30 is moved downward by operating the operation unit 40. The contact portion 26 provided on the fixed side unit 20 side and the contact portion 36 provided on the movable side unit 30 side are in contact with each other, and the distance Y between them is the movement of the movable side unit 30. Corresponds to the stroke. The operation unit 40 may be moved manually or electrically by a drive mechanism.

  As will be described later, the number of press working steps using manufacturing equipment is roughly divided into four steps. For the lower molds 21 and 22 and the upper molds 31 and 32, molds suitable for each process are used, but if there are those that can be used in common, they are used in common. Although the size and shape of the mold are different in each process, the basic configuration is as shown in FIG.

  In addition, although it is a kind of press work, a punching process, a drawing process, etc. are included, and it is not limited to a specific kind of process as this invention.

  Further, FIG. 14 schematically shows a workpiece W as a target of press working, but the form of the work W differs depending on the press working process.

  The fuel cell is assembled by this mold, but since this is a mold configuration that can also be used in progressive mold equipment, this point will be described. Here, description will be made on a case where the metal plates 4 and 5 are used for punching (drawing) for forming the recesses 4g and 5g for accommodating the electrode plates 2 and 3 of the membrane-electrode assembly 10 and punching of the outer shape. To do.

  This drawing process is a process for forming a 150 μm step on the metal plates 4 and 5. FIG. 10C and FIG. 11C show a state in which the concave portions 4g and 5g are formed in the respective metal plates 4 and 5. FIG. By this drawing process, steps 4f and 5f are formed at locations near the boundaries between the peripheral areas 4a and 5a of the metal plates 4 and 5 and the central areas 4b and 5b. Accordingly, concave portions 4g and 5g are formed inside the metal plates 4 and 5, respectively.

  Metal molds for drawing the cathode side metal plate 4 (first and second lower molds 21 and 22 and first and second upper molds 31 and 32), and molds for drawing the anode side metal plate 5 The same mold can be used as the mold. In FIGS. 10 and 11, it is shown in accordance with the posture when assembled, but the posture (vertical direction) when actually set in the mold is the posture of the metal plate 5 shown in FIG. 11. Will be set.

  When performing the drawing process, when the second lower mold 22 descends from above, it first comes into contact with the peripheral regions 4a and 5a of the metal plates 4 and 5. At that time, since the stoppers (contact portions 26 and 36) are not yet in contact with each other, the second upper mold 32 tries to further lower, but the second lower mold 22 is in a fixed state. Therefore, the spring 33 is compressed.

  On the other hand, the first upper mold 31 located in the central regions 4b and 5b is continuously lowered and stopped with the stopper coming into contact with the lower surface of the first upper mold 31 further lower than the lower surface of the second upper mold 32. To do. The stroke until the stopper stops is set for each process. Thereby, drawing processing is performed on the metal plates 4 and 5, and steps (recesses 4g and 5g) are formed. The step size at this time is, for example, about 0.15 mm, and the recesses 4g and 5g corresponding to the thickness of the electrode plates 2 and 3 to be accommodated are formed.

  The results of punching the metal plates 4 and 5 are as shown in FIGS. 10 (d) and 11 (d). In the punching dimension L1 of the anode side metal plate 5 and the punching dimension L2 of the cathode side metal plate 4, L2 is larger, so that the mold used in the punching process is the anode side metal plate 5 and the cathode side. It differs from the metal plate 4. As will be described later, since the caulking cost is required for caulking and sealing the peripheral area 4a of the cathode side metal plate 4 in the caulking process, the dimensions are increased. The movement of the die in this punching is basically the same as the above-described drawing, although the amount of stroke Y is set differently.

  Moreover, the metal mold | die shown in FIG.13, 14 can be used also when performing the drawing process of the standing bending part demonstrated in FIG. The movement of the mold in the drawing process is basically the same as described in the drawing process and the punching process.

<Manufacturing (assembly of fuel cell) process>
Next, a specific manufacturing process when assembling fuel cells will be described. An outline of the manufacturing process is shown in the flowchart of FIG. First, the metal plates 4 and 5 and the membrane / electrode assembly 10 manufactured by the progressive die equipment are set. This state is shown in FIG. A membrane / electrode assembly 10 (with the electrode plates 2 and 3 assembled on both surfaces of the solid polymer electrolyte 1) is set in the metal plate 4 drawn by 90 °. The electrode plate 2 of the membrane / electrode assembly 10 is accommodated in the recess 4 g of the metal plate 4, and the electrode plate 3 is accommodated in the recess 5 g of the metal plate 5. A metal plate 5 is set on the top. The first upper mold 31 includes a recess 31a for escaping the booth 5e that is caulked to the metal plate 5, and a recess for escaping the protrusion on the surface of the metal plate 5 due to the formation of the flow channel groove 9. 31b is provided.

  After setting the state of FIG. 16, the cathode side metal plate 4 is subjected to a drawing process of 45.degree. The second upper mold 32 used at this time is provided with an inclined surface 32c of 45 ° with respect to the horizontal plane as shown in FIG. By operating the inclined surface 32c, the peripheral region 4a bent at 90 ° is once drawn to 45 °. The state at this time is shown in FIG.

  By operating the operation unit 40, the first and second upper molds 31 and 32 descend. When the second lower mold 22 and the second upper mold 32 come into contact with each other, the peripheral region 4a is bent 45 ° inward. When the second upper mold 32 comes into contact with the second lower mold 22, the stoppers (contact parts 26, 36) are not yet in contact (see FIG. 14). The compression process of the coil spring 33 proceeds until the stopper comes into contact. On the other hand, the first upper die 31 is above the metal plate 5 of the fuel cell and is in contact with the metal plate 5 when the second upper die 32 and the second lower die 22 come into contact with each other. Absent. When the stopper comes into contact, the first upper mold 31 is not lowered further and stops in the state shown in FIG. At this time, the lower surface 31 a of the first upper mold 31 presses (contacts) the upper surface of the metal plate 5. Thereby, it can suppress that the center area | regions 4b and 5b of a fuel battery cell deform | transform.

  Note that the lower surface of the metal plate 4 and the upper surface of the first lower mold 21 are not in contact with each other, but are in a state where a gap is formed. In the pressed state, the vertical gap dimension Δh between the upper surface of the second lower mold 22 and the first upper mold 31 is set to about 0.5 mm. Moreover, the thickness of the metal plates 4 and 5 in this case is 0.3 mm. The thickness of the solid polymer electrolyte 1 is 0.025 mm. Therefore, the gap dimension Δh is substantially the same as the thickness of the fuel cell to be caulked and sealed. Thereby, the deformation of the member can be effectively regulated without applying an excessive force to the fuel cell.

  The setting of the angle of 45 ° is preferably 45 ° ± 5 °, more preferably 45 ° ± 1 °. If it exceeds 50 °, there is a possibility that the bent part will not fall down well when performing 0 ° drawing. For example, a phenomenon such as buckling may occur, and it may not be crushed well, the quality of caulking sealing will deteriorate, and problems such as gas leakage will occur. On the other hand, if the angle is smaller than 40 °, it is not preferable because the bent portion does not easily fall down when it is smaller than 40 ° at a time.

  After the 45 ° drawing process is performed as described above, the outer 0 ° drawing process of the cathode side metal plate 4 is performed. Thereby, the crimping process is completed. The die used for the 0 ° external drawing is a different die from the 45 ° drawing, and the press surface 32d is formed in a horizontal plane as shown in FIG. The peripheral region 5a bent at 45 ° in the previous process is further pressed down and tilted inward. As a result, the peripheral area 4a is bent 180 ° in a horizontal state. As a result, the peripheral regions 4a and 5a are sealed with caulking. Further, insulating sheets 11 and 12 are interposed as insulating layers between the peripheral region 4a and the peripheral region 5a, and are sealed in a state in which a short circuit between the metal plates 4 and 5 is prevented.

  In the same manner as shown in FIG. 17, the compression process of the coil spring 33 is performed after the second lower mold 22 and the second upper mold 32 are in contact until the stoppers (contact portions 26 and 36) are in contact. Persisted. Further, the position of the lower surface of the first upper mold 31 is the same as that in FIG. In addition, there is a gap between the first lower mold 21 and the lower surface of the metal plate 4.

  As described above, a process for performing caulking sealing is performed. In particular, when the 90 ° standing bent portion formed in FIG. 12 is tilted inward, it is not tilted at once, but is drawn once to 45 ° and then drawn to 0 °. Caulking sealing is performed in stages. If this is done in one stage, there is no guarantee that the bent part will fall down well, and the sealing state will deteriorate. However, as described above, the drawing process is performed in two stages to ensure sealing. Can do.

  Further, in the caulking sealing step, the central region 5b of the metal plate 5 is brought into contact with the first upper mold 31 to restrict deformation of the central region 5b when performing press working. Further, since a gap is formed between the central region 4a of the metal plate 4 and the first lower mold 21, no pressing force or regulation force acts. Accordingly, it is possible to effectively prevent deformation of the central regions 4b and 5b while preventing an excessive force from acting on the central regions 4a and 5a.

  The fuel battery cell manufactured by the process as described above has a planar shape, which is further processed into an arch shape. 20 shows a schematic configuration of the lower mold 21 and the upper mold 31, and FIG. 19 shows a state immediately after being processed into an arch shape. The lower die 21 is provided with a peripheral pressing portion 21m and a central pressing portion 21n that is a slightly recessed portion than the peripheral pressing portion 21m, and presses the peripheral region 4a and the central region 4b of the cathode side metal plate 4, respectively. . The upper die 31 is also provided with a peripheral pressing portion 31m and a central pressing portion 31n, which is slightly recessed from the peripheral pressing portion 31m, respectively, and a protruding portion of the channel groove 9 of the anode side metal plate 5 and a caulking The peripheral region 4a of the anode side metal plate 4 bent by the sealing is pressed.

  Each pressing part of the lower mold | type 21 and the upper mold | type 31 has the curved shape for processing in an arch shape. Thereby, a planar fuel cell can be pressed into an arch shape. The manufactured arch-shaped fuel cell is as shown in FIGS.

  The caulking-sealed portion of the fuel cell processed into an arch shape is preferably sealed with resin. Since the area to be caulked and sealed has a rectangular frame shape, the area to be resin-sealed also has the same frame shape. Examples of the resin include an epoxy resin, a phenol resin, and a polyolefin resin.

<Usage example>
Next, the usage example of the fuel cell formed in the arch shape is shown in FIG. FIG. 22 is a perspective view showing the external appearance of the fuel cell. The fuel cell includes a main body 60 and a cap 61 that is detachably placed on the tip of the main body 60. This fuel cell is used for charging a secondary battery provided in an electronic device (notebook personal computer, PDA, mobile phone, etc.), but may be used as a main power supply instead of charging.

  The main body 60 has a cylindrical shape, and a power supply terminal 62 is provided at the tip thereof. For example, a USB terminal is used as the power supply terminal 62. Three fuel cells S formed in an arch shape around the main body 60 are arranged along the circumferential direction. The cathode side metal plate 4 is exposed on the surface of the main body 60, and the opening hole 4c for taking in air is also exposed. A mechanism for generating hydrogen gas (not shown) is provided inside the main body 60, and the generated hydrogen gas is supplied into each fuel cell S.

  Next, since the effect in the case of actually forming in arch shape was confirmed, it demonstrates below. First, regarding the size of the fuel cell, the length in the long side direction is 36 mm, the length in the short side direction is 15 mm in the expanded state (before bending into an arch shape), the angle R is 5 mm, and the opening hole 1a. The size of is 2 mm. The protrusion amount of the central regions 4b and 5b with respect to the peripheral regions 4a and 5a is about 0.1 mm to 0.2 mm. The maximum thickness of the fuel cell is 1.5 mm. The radius of the arch when it is formed in an arch shape is 8.5 mm. One cell was used for the experiment.

  The fuel gas used for power generation is hydrogen gas, and the supply amount to the fuel cell is 2 to 3 cc per hour.

  FIG. 21 is a graph comparing the voltage output when processed into an arch shape and when not processed. The horizontal axis of the graph indicates the current density, and the vertical axis indicates the voltage. As can be seen from this graph, the output is higher when processed into an arch shape. This is considered to be because the electrical contact state between the membrane / electrode assembly 10 and the metal plates 4 and 5 is satisfactorily maintained by processing into an arch shape.

<Another embodiment>
The configuration of the fuel cell is not limited to the structure shown in FIGS. For example, the cathode side metal plate 4 has a shape having a large number of opening holes 4 c for taking in air, but the cathode side metal plate 4 may be formed in the same shape as the anode side metal plate 5. Further, the size, number, shape and the like of the opening hole 4c formed in the cathode side metal plate 4 can be appropriately determined.

  In the present embodiment, the flow path groove 9 formed in the anode side metal plate 5 is divided into two press processes, but may be formed by one or three or more step processes.

  In the present embodiment, the metal plate is drawn in the caulking sealing process by setting a predetermined inclination angle to 45 ° and then performing 0 ° drawing. That is, although caulking sealing is performed in two stages, this may be three or more stages. For example, 60 ° → 30 ° → 0 ° can be set. Of course, other angles may be used. Also, it may be set in multiple stages of four or more stages.

  In the assembly process of the present embodiment, the membrane / electrode assembly 10 is assembled into the mold and then set in the mold. When the mold is set in the mold, the cathode side electrode plate 2 and the solid polymer electrolyte are set. 1. Alternatively, the anode side electrode plate 3 may be set in a stacked manner.

  In this embodiment, the peripheral region 4a of the cathode side metal plate 4 is bent and caulked and sealed, but the peripheral region 5a of the anode side metal plate 5 may be bent and caulked and sealed.

  In this embodiment, the arch shape is processed immediately after the caulking sealing process is performed. However, before the arch process is performed, a ring pressing process may be performed for further safety. This processing is a step of pressing the crimping-sealed peripheral regions 4a and 5a slightly inside the region with a press, whereby the sealed state can be made more reliable. As a mold for carrying out the ring pressing process, protrusions formed in a ring shape are provided, and these protrusions are used to press the inner side of the peripheral regions 4a and 5a in a ring shape. Thereby, crimping sealing can be ensured more.

  The shape of the arch (the size of the radius, the protruding height, etc.) when processing into an arch shape can be changed as appropriate. The shape of the arch is not limited to the arc shape, and may be a quadratic curve such as an ellipse or other curved surface shape.

  In the present embodiment, cuts may be made on the surfaces of the metal plates 4 and 5. It becomes easy to process into an arch shape by making a cut. The direction of the cut is preferably a direction that intersects the arch shape (a direction that is orthogonal is particularly preferred), and in the example of FIG. 1, the cut is preferably made along the longitudinal direction. The depth, length, number, etc. of the cuts can be determined as appropriate. The cut is preferably made in at least one of the metal plates 4 and 5, and may be made in both. The cut is preferably formed on the surface of the metal plates 4 and 5 on the side that is deformed into a convex shape. The notches themselves can be formed by pressing, but may be formed by other processing methods.

1 is an external perspective view (anode side) showing the configuration of a fuel cell according to the present invention. FIG. 3 is an external perspective view (cathode side) showing the configuration of the fuel cell according to the present invention. Assembly perspective view showing an example of the fuel battery cell of the present invention The longitudinal cross-sectional view which shows an example of the fuel battery cell of this invention The figure which shows the flow-path groove | channel of the fuel battery cell of FIG. The figure which shows the outline of the manufacturing process of a fuel cell Conceptual diagram showing the configuration of progressive mold equipment Plan view showing the cathode metal sheet manufacturing process Plan view showing manufacturing process of anode side metal plate Sectional drawing which shows the manufacturing process of a cathode side metal plate Sectional drawing which shows the manufacturing process of an anode side metal plate The figure which shows the drawing process of the bending part in the peripheral area of the cathode side metal plate External perspective view showing the configuration of the mold Conceptual diagram showing the cross-sectional structure of the mold Flow chart showing assembly process of fuel cell Sectional drawing which shows the state which set the metal plate and the thin film electrode composition to the metal mold | die Conceptual drawing showing 45 ° drawing of the metal plate on the cathode side Conceptual diagram showing the 0 ° drawing of the cathode side metal plate Conceptual diagram showing ring presser processing Diagram showing the mold for ring press working Experimental data showing the effect of machining into an arch shape The figure which shows the concrete usage example of the fuel cell

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid polymer electrolyte 1a Peripheral part 2 Cathode side electrode plate 3 Anode side electrode plate 4 Cathode side metal plate (2nd metal plate)
4a peripheral area 4b central area 5 anode side metal plate (first metal plate)
5a Peripheral area 5b Central area 5c Inlet 5d Outlet 5e Booth 9 Channel groove 10 Membrane / electrode assembly 11, 12 Insulating sheets 50, 51 Long metal plates 50a, 51a Positioning holes

Claims (3)

A plate-like membrane / electrode assembly and first and second metal plates disposed on both sides of the membrane / electrode assembly, and the peripheral region of these metal plates interpose an insulating layer. In a method for manufacturing a fuel cell that is mechanically sealed in a state,
In the state where the first metal plate having the rising portion formed in the peripheral region, the membrane / electrode assembly, and the second metal plate are set in the vertical direction, the rising portion of the peripheral region of the first metal plate is Tilting inward and mechanically sealing,
And a step of processing the overall shape of the fuel cell from a planar shape to an arch after the step.   The first metal plate functions as a cathode-side metal plate in which a large number of holes for taking in air are formed, and is processed into an arch shape such that the surface of the first metal plate is convex. Item 2. A method for producing a fuel cell according to Item 1.   The method for manufacturing a fuel cell according to claim 2, wherein a cut is formed in the surface of the first metal plate in a direction intersecting with the arch formation direction.

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