Method for manufacturing cell unit for fuel cell and apparatus for manufacturing cell unit for fuel cell

Abstract

To satisfactorily manufacture a cell unit in which a membrane electrode structure and a separator are integrated.SOLUTION: A method for manufacturing a cell unit for a fuel cell includes the steps of: engaging with or fitting a positioned part provided on an outer edge part of a resin frame member of a membrane electrode structure to a rod-like positioning member projecting from an upper surface of a table in a vertical movable manner, and installing the membrane electrode structure on the upper face of the table; mounting a positioning frame on the positioning member so as to press and move the positioning member, while being positioned by the positioning member; mounting a separator on the membrane electrode structure while positioning the outer edge part of the separator by the positioning part provided on the positioning frame; and welding the positioned membrane electrode structure and separator.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for manufacturing a cell unit for a fuel cell, in which a membrane electrode assembly and a separator are integrated to manufacture a cell unit. [Background technology]

[0002] In recent years, technological development has been conducted on fuel cells that contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. A known technology for fuel cell stacks used in this type of fuel cell involves previously integrating the resin frame members of a membrane electrode assembly and separators by welding, and then stacking the integrated cells to form a stack (see, for example, Patent Document 1). In the method described in Patent Document 1, tapered positioning pins protruding from a base are inserted into positioning holes in the membrane electrode assembly and separators, and then the two are joined by welding using a laser beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7062729 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the membrane electrode assembly has positioning portions (e.g., positioning holes) for welding provided in the thin-walled resin frame member, there is a risk that the positioning portions may interfere with the positioning members due to dimensional tolerances, etc., and that the resin frame member may be damaged when manufacturing the cell unit. [Means for solving the problem]

[0005] One aspect of the present invention is a method for manufacturing a cell unit for a fuel cell, in which a membrane electrode structure having a membrane electrode assembly including an electrolyte membrane and electrodes and a resin frame member supporting the membrane electrode assembly is integrated with a separator to manufacture a cell unit, the method comprising the steps of: placing the membrane electrode structure on the top surface of the table by engaging or fitting a positioned portion provided on the outer edge of the frame member with a rod-shaped positioning member that protrudes from the top surface of a table so as to be movable up and down; mounting a positioning frame on the positioning member so as to push the positioning member while being positioned by the positioning member; mounting a separator on the membrane electrode structure while the outer edge of the separator is positioned by the positioning portion provided on the positioning frame; and welding the positioned membrane electrode structure and separator together.

[0006] Another aspect of the present invention is a fuel cell unit manufacturing apparatus for integrating a membrane electrode assembly having a membrane electrode assembly including an electrolyte membrane and electrodes and a resin frame member supporting the membrane electrode assembly, and a separator to manufacture a cell unit, the apparatus comprising: a table having an upper surface on which the membrane electrode assembly is placed and rod-shaped positioning members protruding from the upper surface so as to engage or fit with positioning portions provided on the outer edge of the frame member; and a positioning frame having a contact portion that abuts against the positioning member while being positioned by the positioning member and a positioning portion that positions the separator, the positioning frame being mounted on the positioning member via the abutment portion. The table further has support portions that support the positioning member in a liftable manner so that the positioning member can be lowered when the positioning frame is mounted via the abutment portion. [Effects of the Invention]

[0007] According to the present invention, the cell unit can be manufactured satisfactorily without damaging the frame member of the membrane electrode assembly. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a perspective view showing a schematic overall configuration of a fuel cell stack including a cell unit manufactured by a manufacturing method for a cell unit for a fuel cell according to an embodiment of the present invention; [Figure 2] 2 is a cross-sectional view showing the main configuration of the power generation region of a cell stack included in the fuel cell stack of FIG. 1. [Figure 3] FIG. 2 is an exploded perspective view of a cell unit included in the fuel cell stack of FIG. 1. [Figure 4A] 1 is a perspective view showing a schematic configuration of a manufacturing apparatus for a cell unit for a fuel cell stack according to an embodiment of the present invention; [Figure 4B] Enlarged view of part B in Figure 4A. [Figure 5A] FIG. 4B is a perspective view of a table included in the manufacturing apparatus of FIG. 4A. [Figure 5B] 5B is a perspective view showing a state in which an integrated electrode assembly is mounted on the upper surface of the table of FIG. 5A. [Figure 6] FIG. 5B is a cross-sectional view taken along line VI-VI in FIG. 5A. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 4B. [Figure 8] 5A and 5B are diagrams showing an example of the operation of a manufacturing apparatus for a cell unit for a fuel cell stack according to an embodiment of the present invention. [Figure 9] 5A to 5C are diagrams illustrating a welding step included in the method for assembling a cell unit for a fuel cell stack according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 9. A fuel cell stack according to an embodiment of the present invention is a main component of a fuel cell. The fuel cell is mounted, for example, in a vehicle and can generate electric power for driving the vehicle. The fuel cell can also be mounted in moving bodies other than vehicles, such as aircraft and ships, robots, and various industrial machines.

[0010] First, the overall configuration of the fuel cell stack will be described briefly. FIG. 1 is a perspective view showing the overall configuration of a fuel cell stack 100 according to an embodiment of the present invention. For convenience, the three mutually orthogonal axial directions shown in the figure are defined as the front-rear direction, the left-right direction, and the up-down direction, and the configuration of each part will be described in accordance with these definitions. These directions are not necessarily the same as the front-rear direction, the left-right direction, and the up-down direction of a vehicle. The front-rear direction in FIG. 1 is the stacking direction of the fuel cell stack 100, and when assembling the fuel cell stack 100, the stacking direction is aligned with the direction of gravity.

[0011] 1, the fuel cell stack 100 has a cell stack 10, end units 40 arranged at both front and rear ends of the cell stack 10, and a case 30 arranged around the cell stack 10, and has a generally rectangular parallelepiped shape as a whole. The length of the fuel cell stack 100 in the left-right direction is longer than the length in the up-down direction.

[0012] The case 30 has four generally rectangular side walls 300 that face the top, right, bottom, and left sides of the cell stack 10. These four side walls 300 form a generally box-shaped storage space SP0 that is open on the front and back. The case 30 is made of a metal such as aluminum or iron.

[0013] Part A of Fig. 1 shows a cutaway view of a side wall 300 of the case 30. As shown in part A of Fig. 1, the cell stack 10 has a plurality of power generating cells 1 (for convenience, only a single power generating cell 1 is shown) arranged in the storage space SP0.

[0014] The power-generating cell 1 has an integrated electrode assembly (UEA) 2 having a membrane electrode assembly including an electrolyte membrane and electrodes, and separators 3 arranged on both the front and rear sides of the integrated electrode assembly 2 and sandwiching the integrated electrode assembly 2. The integrated electrode assemblies 2 and separators 3 are arranged alternately in the front-to-rear direction. The integrated electrode assembly 2 can also be called a membrane electrode structure. A power-generating region that generates electricity through an electrochemical reaction between hydrogen and oxygen is formed in the center of the power-generating cell 1 in the left-to-right and up-to-down directions.

[0015] A plurality of guide members 45 (only some of which are shown) are interposed between the cell stack 10 and the side wall 300 of the case 30. The guide members 45 are rod- or plate-shaped members extending in the front-to-rear direction, and are attached in advance to the inner surface of the side wall 300. When assembling the fuel cell stack 100, for example, the rear end unit 40 is laid on its side, and a plurality of power-generating cells 1 guided by the guide members 45 are stacked on top of it to assemble the cell stack 10. Furthermore, the front end unit 40 is mounted on top of the cell stack 10.

[0016] FIG. 2 is a cross-sectional view showing the main components of the power generation region of the cell stack 10, more specifically, a cross-sectional view taken along a plane extending in the vertical and front-rear directions. As shown in FIG. 2, the separator 3 has a pair of front and rear metal thin plates, a front plate 3F and a rear plate 3R, each of which has a corrugated cross section. The front plate 3F extends in the vertical and left-right directions and has a front surface 3Fa and a rear surface 3Fb. The rear plate 3R extends in the vertical and left-right directions and has a front surface 3Ra and a rear surface 3Rb. The opposing rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R are joined at their outer peripheral edges by welding or the like. This integrally joins the front plate 3F and the rear plate 3R to form the separator 3. The separator 3 is made of a conductive material with excellent corrosion resistance, such as stainless steel, titanium, or a titanium alloy.

[0017] A cooling flow path PAw through which a coolant flows is formed inside the separator 3 surrounded by the front plate 3F and the rear plate 3R, that is, between the rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R. The flow of the coolant cools the power generation surface of the power generation cell 1. Water, for example, can be used as the coolant. The surface of the separator 3 facing the integrated electrode assembly 2 (the front surface 3Fa and the rear surface 3Rb) is formed unevenly by press molding or the like to form a gas flow path between the separator 3 and the integrated electrode assembly 2.

[0018] More specifically, an anode flow path PAa, through which a fuel gas containing hydrogen flows, is formed between the front surface 2a of the integrated electrode assembly 2 and the rear plate 3R of the separator 3 facing this front surface 2a. A cathode flow path PAc, through which an oxidant gas containing oxygen flows, is formed between the rear surface 2b of the integrated electrode assembly 2 and the front plate 3F of the separator 3 facing this rear surface 2b. The fuel gas and the oxidant gas are sometimes referred to as reactant gases without distinction. A compressive load F is applied to the cell stack 10 in the front-rear direction during assembly of the fuel cell stack 100. After assembly of the fuel cell stack 100 is complete, this compressive load F is maintained by fastening a pair of front and rear end units 40 to the case 30.

[0019] A single integrated electrode assembly 2 and a single separator 3 are integrated in advance by welding to form a cell unit. Figure 3 is an exploded perspective view of a cell unit 1a showing the general configuration of the integrated electrode assembly 2 and separator 3. The cell unit 1a is formed by joining a pair of plates 3F, 3R to form the separator 3, and then, for example, overlapping the rear plate 3R of the separator 3 on the front surface 2a of the integrated electrode assembly 2. Although not shown in Figure 3, the integrated electrode assembly 2 and the separator 3 have positioning portions on their outer edges that are used to position them when they are welded.

[0020] As shown in FIG. 3, the integrated electrode assembly 2 includes a membrane electrode assembly (MEA) 20 and a frame 21. The membrane electrode assembly 20 includes an electrolyte membrane, an anode electrode provided on the front surface of the electrolyte membrane, and a cathode electrode provided on the rear surface of the electrolyte membrane. The electrolyte membrane is, for example, a solid polymer electrolyte membrane. The anode electrode is formed on the front surface of the electrolyte membrane and includes an electrode catalyst layer that serves as a reaction field for electrode reactions, and a gas diffusion layer that is provided on the front surface of the electrode catalyst layer and diffuses and supplies fuel gas. The cathode electrode is formed on the rear surface of the electrolyte membrane and includes an electrode catalyst layer that serves as a reaction field for electrode reactions, and a gas diffusion layer that is provided on the rear surface of the electrode catalyst layer and diffuses and supplies oxidant gas.

[0021] At the anode electrode, fuel gas (hydrogen) supplied via the anode flow channel PAa (Fig. 2) and gas diffusion layer is ionized by the action of a catalyst and moves through the electrolyte membrane to the cathode electrode side. The electrons generated at this time pass through an external circuit and are extracted as electrical energy. At the cathode electrode, oxidant gas (oxygen) supplied via the cathode flow channel PAc (Fig. 2) and gas diffusion layer reacts with hydrogen ions introduced from the anode electrode and electrons transferred from the anode electrode, producing water. The produced water provides an appropriate humidity to the electrolyte membrane, and excess water is discharged outside the integrated electrode assembly 2.

[0022] The frame 21 is a film-like member having a substantially rectangular shape, and its outer edge is formed by four sides (top side 211, right side 212, bottom side 213, and left side 214). The frame 21 is made of insulating resin, rubber, or the like. A substantially rectangular opening 21a is provided in the center of the frame 21. The membrane electrode assembly 20 is provided so as to cover the entire opening 21a, and the outer edge of the membrane electrode assembly 20 is supported by the frame 21. On the left side of the opening 21a in the frame 21, three through holes 201 to 203 are opened in a vertically aligned manner, penetrating the frame 21 in the front-to-rear direction. On the right side of the opening 21a, three through holes 204 to 206 are opened in a vertically aligned manner, penetrating the frame 21 in the front-to-rear direction.

[0023] The separator 3 has a generally rectangular shape overall, with four sides (top side 311, right side 312, bottom side 313, and left side 314) defining its outer periphery. The separator 3 has an uneven cathode flow path PAc (FIG. 2) and an uneven anode flow path PAa (FIG. 2) formed on its front and rear sides facing the membrane electrode assembly 20, respectively. The separator 3 has through-holes 301-306 that penetrate the separator 3 in the front-rear direction at positions corresponding to the through-holes 201-206 of the frame 21. The through-holes 301-306 are connected to the through-holes 201-206 of the frame 21, respectively. A collection of these mutually connected through-holes 201-206 and 301-306 forms a plurality of flow paths that penetrate the cell stack 10 and extend in the front-rear direction.

[0024] 1, the rear end unit 40 has a plurality of through holes 401 to 406 that penetrate the end unit 40 in the front-rear direction at positions corresponding to the through holes 201 to 206 and 301 to 306. Note that the front end unit 40 does not have the through holes 401 to 406.

[0025] A fuel gas tank storing high-pressure fuel gas is connected to through-hole 401 via an ejector, injector, etc., and the fuel gas is supplied to fuel cell stack 100 via through-hole 401, as shown by the solid arrow. This fuel gas is guided to anode flow path PAa via through-holes 201 and 301. After passing through anode flow path PAa, the fuel gas passes through through-holes 206 and 306 and is discharged from through-hole 406, as shown by the solid arrow.

[0026] An oxidant gas supply compressor is connected to through-hole 404, and as indicated by the dotted arrow, oxidant gas compressed by the compressor is supplied to fuel cell stack 100 via through-hole 404. This oxidant gas is guided to cathode flow path PAc via through-holes 204 and 304. After passing through cathode flow path PAc, the oxidant gas passes through through-holes 203 and 303 and is discharged from through-hole 403 as indicated by the dotted arrow.

[0027] A pump for supplying a cooling medium is connected to through-hole 405, and as shown by the dashed-dotted arrow, the cooling medium is supplied to fuel cell stack 100 through through-hole 405. This cooling medium is guided to cooling flow passage PAw between front plate 3F and rear plate 3R of separator 3 through through-holes 205 and 305. After passing through cooling flow passage PAw, the cooling medium passes through through-holes 202 and 302 and is discharged from through-hole 402 as shown by the dashed-dotted arrow.

[0028] The above is a schematic configuration of the fuel cell stack 100. This embodiment is characterized in that the cell unit 1a is manufactured by previously integrating a single integrated electrode assembly 2 and a single separator 3, i.e., in the cell unit manufacturing process. This point will be described below.

[0029] The cell unit 1a is manufactured using a manufacturing apparatus. FIG. 4A is a perspective view showing the schematic configuration of the manufacturing apparatus 200, showing a state during the cell unit manufacturing process. In the description of the manufacturing process, the directions corresponding to the up-down direction and the front-back direction in FIG. 1 are defined as the front-back direction and the up-down direction, respectively, as shown in FIG. 4A. The downward direction in the up-down direction in FIG. 4A corresponds to the direction of gravity. As shown in FIG. 4A, the manufacturing apparatus 200 has a table 50 on which the integrated electrode assembly 2 is placed, and a frame 60 mounted on the table 50.

[0030] FIG. 5A is a perspective view of a table 50. As shown in FIG. 5A, the table 50 has a plate 51 that is generally rectangular in plan view and a plurality of positioning pins 52 that protrude from an upper surface 511 of the plate 51. Legs 53 are provided on the lower surface of the plate 51. The positioning pins 52 are provided at positions corresponding to the positioning portions of the integrated electrode assembly 2. Specifically, the positioning pins 52 are provided near the front end of the plate 51 and at the center in the left-right direction, near the right end of the plate 51 and behind the center in the front-rear direction, and near the left end of the plate 51 and forward of the center in the front-rear direction. The configurations of the plurality of positioning pins 52 are identical to each other. The positions and number of the positioning pins 52 are not limited to those shown in FIG. 5A.

[0031] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5A. As shown in FIG. 6, the positioning pin 52 is supported by a holder 54 so as to be movable up and down. The holder 54 has a substantially cylindrical peripheral wall 541 and a flange 542 protruding outward from the outer periphery of the peripheral wall 541. A substantially circular through-hole 510 is formed in the plate 51, penetrating the plate 51 in the up-down direction. The peripheral wall 541 of the holder 54 is inserted into the through-hole 510 from below the plate 51, and in this state, the flange 542 is fastened to a lower surface 512 of the plate 51 with a bolt 55. At this time, the upper end of the peripheral wall 541 is positioned below the upper surface 511 of the table 50 (plate 51). A spring seat 543 protruding radially inward is provided at the lower end of the peripheral wall 541.

[0032] The positioning pin 52 has a generally cylindrical shape and is inserted into the inside of a peripheral wall 541 of the holder 54 so as to be movable up and down along the inner peripheral surface of the peripheral wall 541. The upper end of the positioning pin 52 has a tapered portion 521 that is generally conical and tapered upward. The tapered portion 521 protrudes above the upper surface 511 of the table 50. The lower end of the positioning pin 52 is provided with a stopper 522 that protrudes radially outward. The stopper 522 is located below a spring seat 543 of the holder 54. The positioning pin 52 has a small-diameter portion 523 that extends a predetermined distance above the stopper 522 and has a stepped portion 524 that reduces the diameter of the outer peripheral surface. An annular space SP1 is defined between the outer peripheral surface of the small-diameter portion 523 and the inner peripheral surface of the peripheral wall 541, and a spring (e.g., a coil spring) 56 is inserted in this space SP1.

[0033] The upper end of spring 56 abuts against step 524 of positioning pin 52, and the lower end abuts against spring seat 543 of holder 54. Spring 56 is a compression spring, and urges positioning pin 52 upward via step 524. In the initial state where no downward pressing force is acting on positioning pin 52, stopper 522 of positioning pin 52 abuts against spring seat 543, and the length from upper surface 511 of table 50 to upper end surface 525 of positioning pin 52, i.e., the protrusion amount of positioning pin 52, is at its maximum (maximum height H1). At this time, the diameter of positioning pin 52 along upper surface 511, i.e., the diameter of positioning pin 52 at the portion intersecting with an imaginary plane formed by extending upper surface 511, is at its maximum (maximum diameter D1).

[0034] 5B is a perspective view showing a state in which the integrated electrode assembly 2 is mounted on the upper surface 511 of the table 50. As shown in FIG. 5B, fitting grooves 23 that fit into guide member 45 (FIG. 1) when assembling the fuel cell stack 100 are provided on four sides 211 to 214 of the outer edge of the frame 21 of the integrated electrode assembly 2. The fitting grooves 23 each have a pair of recesses 23a, 23b that are arranged side by side along each of the sides 211 to 214. Although not shown, the guide member 45 has a pair of protrusions that protrude toward the frame 21, and the pair of protrusions of the guide member 45 fit into the pair of recesses 23a, 23b.

[0035] The multiple positioning pins 52 are provided corresponding to the positions of the recesses 23a on the three sides 211, 212, and 214 of the frame. The width W1 (FIG. 4B) of the recesses 23a is, for example, the same as the maximum diameter D1 (FIG. 6) of the positioning pins 52, and the recesses 23a fit into the positioning pins 52. This allows the integrated electrode assembly 2 to be set on the table in a state where it is positioned based on the recesses 23a. Note that the width W1 of the recesses 23a may be smaller than the maximum diameter D1.

[0036] From the state shown in FIG. 5B, as shown in FIG. 4A, a resin frame 60 is mounted above the positioning pin 52 so as to cover the positioning pin 52. The frame 60 has four frame portions 61 to 64 extending along the respective sides 211 to 214 of the integrated electrode assembly 2, and has a generally rectangular frame shape as a whole. The height (vertical length) of the frame 60 is greater than the maximum height H1 ( FIG. 6 ) of the positioning pin 52. The three frame portions 61, 62, and 64 are provided with protruding portions 65 that protrude toward the integrated electrode assembly 2 in correspondence with the fitting groove 23 of the integrated electrode assembly 2. Although not shown, the shape of the protruding portions 65 in a plan view is substantially the same as the shape of the pair of convex portions of the guide member 45.

[0037] Fig. 4B is an enlarged view of portion B in Fig. 4A. Fig. 4B also shows separator 3 mounted on the upper surface of integrated electrode assembly 2. As shown in Fig. 4B, protrusion 65 has a pair of protrusions 65a, 65b corresponding to the pair of recesses 23a, 23b of integrated electrode assembly 2. Separator 3 has a pair of recesses 3a, 3b corresponding to the pair of recesses 23a, 23b, and positioning pin 52 is disposed inside recess 3a.

[0038] The width W2 of the recess 3a of the separator 3 is wider than the width W1 of the recess 23a of the integrated electrode assembly 2. More specifically, the width of the recess 3a is equal to the width of the protrusion 65a. This allows the recess 3a of the separator 3 to be mounted on the upper surface of the integrated electrode assembly 2 while being positioned along the side wall surface 650 of the protrusion 65a that rises above the table 50.

[0039] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 4B. As shown in FIG. 7, a bottomed groove 66 is provided in the bottom surface of the protrusion 65a of the frame 60, facing upward. The bottomed groove 66 has a truncated cone shape and has an inclined surface 661 with the same inclination angle as the tapered portion 521 of the positioning pin 52. The positioning pin 52 is inserted into the bottomed groove 66 from below. At this time, the inclined surface 661 abuts against the tapered portion 521, thereby applying a downward pressing force to the positioning pin 52. The downward pressing force is generated by the weight of the frame 60, but is greater than the biasing force of the spring 56. As a result, the spring 56 contracts, and the positioning pin 52 is pressed downward.

[0040] The positioning pin 52 is pushed until the lower end surface of the protruding portion 65 of the frame 60 abuts against the upper surface of the integrated electrode assembly 2. In the state of FIG. 7 where the positioning pin 52 is pushed downward to the maximum, the amount of protrusion of the positioning pin from the upper surface 5111 of the table 50 is shorter than H1 in FIG. 6 and is at its minimum (minimum height H2). At this time, the diameter of the positioning pin 52 along the upper surface 511 is smaller than D1 in FIG. 6 and is at its minimum (minimum diameter D2).

[0041] Although there is some variation in width W1 (FIG. 4B) of recess 23a of integrated electrode assembly 2 due to dimensional tolerances, etc., width W1 is at least greater than minimum diameter D2. Therefore, even if width W1 is smaller than maximum diameter D1 (FIG. 6) of positioning pin 52 in the initial state, frame 21 of integrated electrode assembly 2 can be placed on upper surface 511 of table 50 without strongly interfering with positioning pin 52. As a result, damage to frame 21 can be prevented.

[0042] The manufacturing method for a fuel cell unit according to this embodiment can be summarized as follows. First, the integrated electrode assembly 2 is picked up by the hand of a robot (not shown) and carried above the table 50. Then, as shown in FIG. 5B, the recesses 23a on the outer edge of the integrated electrode assembly 2 are fitted onto the positioning pins 52 protruding from the upper surface 511 of the table 50, and the integrated electrode assembly 2 is placed on the upper surface 511 of the table 50 while being positioned relative to the table 50 (membrane electrode structure installation process). The integrated electrode assembly 2 is positioned by the positioning pins 52 at three locations around the periphery, so the position of the integrated electrode assembly 2 can be determined with high precision.

[0043] Next, the frame 60 is grasped by a robot hand (not shown), and as shown in FIG. 4A, the frame 60 is mounted above the positioning pins 52 (frame mounting process). FIG. 8 is a diagram showing the position of the positioning pins 52 (two-dot chain line) before the frame 60 is mounted and the position of the positioning pins 52 (solid line) after the frame 60 is mounted. As shown in FIG. 8, before the frame 60 is mounted, the positioning pins 52 protrude upward to the maximum. Therefore, if the width W1 of the recess 23a of the integrated electrode assembly 2 is narrower than the maximum diameter D1 of the positioning pin 52, the edge of the recess 23a of the integrated electrode assembly 2 will come into contact with the tapered portion 521, as shown by the two-dot chain line in FIG. 8. As a result, the integrated electrode assembly 2 will rise above the upper surface 511 of the table 50.

[0044] At this time, when the frame 60 is placed on the upper surface of the positioning pin 52, the positioning pin 52 is inserted into the bottomed groove 66, and before the bottom surface of the frame 60 contacts the upper surface of the frame 21 of the integrated electrode assembly 2, the inclined surface 661 of the bottomed groove 66 of the convex portion 65a comes into contact with the tapered portion 521 of the positioning pin 52, and the positioning pin 52 is pushed downward. As a result, the diameter of the positioning pin 52 along the upper surface 511 of the table 50 becomes smaller than the maximum diameter D1, and as the positioning pin 52 descends, the integrated electrode assembly 2 can be lowered until it abuts against the upper surface 511 of the table 50.

[0045] After the frame 21 of the integrated electrode assembly 2 is mounted on the upper surface 511 of the table 50, the bottom surface of the frame 60 abuts against the upper surface of the frame 21. This allows the integrated electrode assembly 2 to be held in a positioned state. The bottom surface of the frame 60 may be raised a predetermined amount above the upper surface of the frame 21. This reliably prevents the weight of the frame 60 from acting on the frame 21.

[0046] Next, the separator 3 is sucked by a robot hand (not shown) and mounted on the top surface of the integrated electrode assembly 2 (separator mounting process). At this time, the separator 3 is mounted on the top surface of the electrode assembly 2 along the side wall surface 650 while being positioned by fitting the recessed portions 3a of the separator 3 into the protruding portions 65a of the frame 60. Since the separator 3 is positioned by the protruding portions 65a at three locations around the periphery, the position of the separator 3 can be determined with high precision.

[0047] Next, with the integrated electrode assembly 2 and the separator 3 positioned on the table, a welding machine (not shown, for example, a laser processing machine) is used to weld the frame 21 of the integrated electrode assembly 2 to the separator 3 (welding process). Welding is performed at a plurality of predetermined welding portions of the frame 21. The welding portions can be provided, for example, near the fitting grooves 23 of the frame 21. The welding portions can also be provided near the corners of the frame 21.

[0048] FIG. 9 is a cross-sectional view schematically illustrating the configuration of the welded portion. As shown in FIG. 9, a substantially circular through-hole 3c is pre-opened in the front plate 3F of the separator 3 facing the welded portion 25. A laser beam LB is irradiated onto the welded portion 25 using a laser processing machine attached to the hand of a robot (not shown). That is, the laser beam LB is irradiated from above the separator 3 through the through-hole 3c toward the rear plate 3R, as indicated by the arrow. This heats the welded portion 25, and the rear plate 3R of the separator 3 and the frame 21 can be welded together via the welded portion 25. Once the integrated electrode assembly 2 and the separator 3 are welded together, the manufacture of the cell unit 1a is complete.

[0049] When assembling the fuel cell stack 100, the cell units 1a are picked up by a robot hand (not shown), and multiple cell units 1a are stacked while positioning them by fitting the fitting grooves 23 (recesses 23a, 23b) of the frame 21 into the guide members 45 previously installed inside the case. By stacking the cell units 1a, the number of movements of the robot hand is reduced compared to when the integrated electrode assemblies 2 and separators 3 are stacked separately, and the stacking process can be completed in a short time.

[0050] The width W1 of the recess 23a in the frame 21 of the integrated electrode assembly 2 is narrower than the width of the recess 3a in the separator 3, and the edge of the recess 23a protrudes outward beyond the edge of the recess 3a. This ensures an insulating distance between a pair of separators 3, 3 arranged in the front-to-rear direction via the integrated electrode assembly 2. The fitting groove 23 in the frame 21 fits into the guide member 45, and the positioning of the cell unit 1a is performed using the recesses 23a, 23b in the frame 21 rather than the recesses 3a, 3b in the separator 3.

[0051] According to this embodiment, the following effects can be achieved. (1) A method for manufacturing a cell unit for a fuel cell, which manufactures a cell unit 1a by integrating an integrated electrode assembly 2 having a membrane electrode assembly 20 including an electrolyte membrane, an anode electrode, and a cathode electrode, a resin frame 21 supporting the membrane electrode assembly 20, and a separator 3, includes the following steps: That is, the process includes the steps of installing the integrated electrode assembly 2 on the upper surface 511 of the table 50 by fitting the recessed portion 23a of the fitting groove 23 provided on the outer edge of the frame 21 onto the positioning pin 52 that protrudes from the upper surface 511 of the table 50 so as to be movable up and down, (membrane electrode structure installation step), a step of mounting the frame 60 on the positioning pin 52 so as to push the positioning pin 52 while being positioned by the positioning pin 52 (frame mounting step), a step of mounting the separator 3 on the integrated electrode assembly 2 while the recessed portion 3a of the separator 3 is positioned by the protrusion 65a provided on the frame 60, (separator mounting step), and a step of welding the positioned integrated electrode assembly 2 and the separator 3 together (welding step) (Figures 4A, 4B, 5B, 9).

[0052] As a result, after the integrated electrode assembly 2 is fitted onto the positioning pins 52 and mounted on the upper surface 511 of the table 50, the positioning pins 52 are pushed downward by the weight of the frame 60 before the separator 3 is mounted on the upper surface of the integrated electrode assembly 2. Therefore, when the separator 3 is mounted, it is possible to prevent the weight of the separator 3 from acting on the integrated electrode assembly 2 in a state where the integrated electrode assembly 2 is floating above the upper surface of the table 50, and it is possible to prevent damage to the positioning recesses 23a of the frame 21.

[0053] (2) A fuel cell unit manufacturing apparatus for manufacturing a cell unit 1a by integrating an integrated electrode assembly 2 having a membrane electrode assembly 20 including an electrolyte membrane, an anode electrode, and a cathode electrode, and a resin frame 21 supporting the membrane electrode assembly 20, and a separator 3, has the following configuration: A table 50 has an upper surface 511 on which the integrated electrode assembly 2 is placed and positioning pins 52 protruding from the upper surface 511 so as to fit into recesses 23a provided on the outer edge of the frame 21, and a frame 60 having bottomed grooves 66 that are positioned by the positioning pins 52 and come into contact with the positioning pins 52, and protrusions 65a that position the separators 3, and is mounted on the positioning pins 52 via the bottomed grooves 66 ( FIGS. 4A , 4B , and 5B ). The table 50 further includes a holder 54 that supports the positioning pin 52 so that the positioning pin 52 can be raised and lowered when the frame 60 is mounted via the bottomed groove 66 (FIGS. 6 and 7).

[0054] With this configuration, the positioning pins 52 move down when the frame 60 is mounted, so that the integrated electrode assembly 2 can be reliably installed on the upper surface 511 of the table 50 before the separator 3 is mounted on the upper surface of the integrated electrode assembly 2. As a result, when the integrated electrode assembly 2 is floating above the upper surface 511 of the table 50, the weight of the separator 3 does not act on the integrated electrode assembly 2, so that cracks can be prevented from occurring in the frame 21 starting from the recesses 23a, and the cell unit 1a can be manufactured satisfactorily.

[0055] (3) The frame 60 has a generally U-shaped extension along the outer edge of the separator 3 so as to surround the bottomed groove 66, and has a side wall surface 650 that constitutes a positioning portion ( FIG. 4B ). The positioning pin 52 is inserted into the bottomed groove 66, and the surface of the bottomed groove 66 abuts against the positioning pin 52. However, because the side wall surface 650 extends so as to surround the bottomed groove 66, the recess 23a of the frame 21 that fits into the positioning pin 52 protrudes beyond the side wall surface 650 and beyond the recess 3a of the separator 3. Therefore, when assembling the fuel cell stack 100, the recess 23a of the frame 21 fits into the guide member 45 and functions as a positioning portion for the cell unit 1a. This ensures an insulating distance between a pair of separators 3, 3 that are arranged in the front-rear direction with the integrated electrode assembly 2 sandwiched therebetween. Furthermore, since the recesses 3a and 3b of the separator 3 are disposed near the recesses 23a and 23b of the frame 21, the rigidity of the recesses 23a and 23b of the frame 21 can be increased.

[0056] (4) The positioning pin 52 has a tapered portion 521 at its upper end that tapers upward so as to create a gap between the positioning pin 52 and the protrusion 65a of the frame 21 when the positioning pin 52 is pressed downward via the bottomed groove 66 ( FIG. 7 ). This allows a downward pressure to be applied to the positioning pin 52 uniformly in the circumferential direction via the bottomed groove 66. Furthermore, when the positioning pin 52 is pressed downward, the integrated electrode assembly 2 can be reliably placed on the upper surface 511 of the table 50.

[0057] The above embodiment can be modified in various ways. Some modified examples will be described below. In the above embodiment, the outer edge of the resin frame 21 (frame member) that supports the membrane electrode assembly 20 is provided with a recess 23a as a positioning target portion, and the recess 23a is adapted to fit onto the positioning pin 52, but the positioning target portion may be a through-hole instead of a groove. In the above embodiment, the positioning target portion is adapted to fit onto the positioning pin, but it may be adapted to engage with the positioning pin instead of fit. In the above embodiment, the tapered portion 521 is provided at the upper end of the positioning pin 52, but the configuration of the positioning member is not limited to that described above.

[0058] In the above embodiment, the tapered portion 521 of the positioning pin 52 is abutted against the inclined surface 661 of the bottomed groove 66 of the frame 60, but the configuration of the abutment is not limited to that described above. In the above embodiment, the separator 3 is positioned relative to the frame 60 by the side wall surface 650 of the protrusion 65a, but the configuration of the positioning portion is not limited to that described above. The separator 3 may be positioned at a location other than the location where the positioning pin is installed (for example, a corner where each side 311 to 314 intersects). Therefore, the recesses 3a and 3b of the separator 3 may not be provided. In other words, the configuration of the positioning frame is not limited to the above-described frame 60, and may be any other configuration as long as it has an abutment portion that abuts against the positioning member while being positioned by the positioning member, and a positioning portion that positions the separator.

[0059] In the above embodiment, the positioning pin 52 is supported by the holder 54 provided on the table 50 so as to be movable up and down, but the configuration of the support portion is not limited to that described above. The table may have any configuration as long as it has an upper surface on which the membrane electrode assembly is placed, a positioning member protruding from this upper surface, and a support portion that supports the positioning member so that it can be raised and lowered. In the above embodiment, the guide member 45 is supported by the case 30, but it may also be supported by a pair of end units 40. For example, a recess or a through hole may be formed in the end unit 40, and the front and rear ends of the guide member 45 may be supported by the recess or through hole. The cross-sectional shape of the guide member is not limited to that described above and may be, for example, approximately circular.

[0060] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modifications as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other.

[0061] 1a cell unit, 2 integrated electrode assembly, 3 separator, 3a, 3b recess, 10 cell stack, 20 membrane electrode assembly, 21 frame, 23a, 23b recess, 25 welded portion, 45 guide member, 50 table, 52 positioning pin, 54 holder, 60 frame, 65 protrusion, 65a, 65b convex portion, 66 bottomed groove, 100 fuel cell stack, 200 manufacturing apparatus, 511 upper surface, 521 tapered portion, 650 side wall surface, 661 inclined surface

Claims

1. A method for manufacturing a cell unit for a fuel cell, comprising integrating a separator and a membrane electrode structure having a membrane electrode assembly including an electrolyte membrane and an electrode, and a resin frame member supporting the membrane electrode assembly, the method comprising the steps of: a step of installing the membrane electrode assembly on the upper surface of the table by engaging or fitting a positioned portion provided on an outer edge of the frame member with a rod-shaped positioning member protruding from the upper surface of the table so as to be movable up and down; a step of mounting a positioning frame on the positioning member so as to push and move the positioning member while being positioned by the positioning member; a step of mounting the separator on the membrane electrode assembly while positioning an outer edge of the separator using a positioning portion provided on the positioning frame; and welding the positioned membrane electrode assembly and the separator together.

2. 1. A manufacturing apparatus for a fuel cell unit, which manufactures a cell unit by integrating a separator and a membrane electrode structure having a membrane electrode assembly including an electrolyte membrane and electrodes and a resin frame member that supports the membrane electrode assembly, a table having an upper surface on which the membrane electrode assembly is placed and a rod-shaped positioning member protruding from the upper surface so as to engage or fit with a positioned portion provided on an outer edge of the frame member; a positioning frame having a contact portion that contacts the positioning member while being positioned by the positioning member, and a positioning portion that positions the separator, the positioning frame being mounted on the positioning member via the contact portion; The manufacturing apparatus for a fuel cell unit is characterized in that the table further has a support portion that supports the positioning member so that it can be raised and lowered when the positioning frame is loaded via the abutment portion, so that the positioning member descends.

3. 3. The fuel cell unit manufacturing apparatus according to claim 2, The positioning frame extends along the outer edge of the separator so as to surround the abutment portion, and has a side wall surface that constitutes the positioning portion.

4. 4. The fuel cell unit manufacturing apparatus according to claim 2, wherein: The positioning member has a tapered portion formed at its upper end so as to taper upwards, so as to create a gap between the positioning member and the positioned portion when the positioning member is pushed downward via the abutment portion.

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