Fuel cell stack assembly method and stacking device

Abstract

To configure a cell laminate of a fuel cell stack accurately.SOLUTION: An assembly method for a fuel cell stack includes a lamination step of forming a cell laminate by alternately laminating a film electrode structure body including an electrolyte film and an electrode, and a separator 3 in a predetermined region. The lamination step includes a transportation step of adsorbing the separator 3 through an adsorption pad 74 and transporting the separator over the predetermined region, a lowering step of lowering the separator 3 while positioning the separator along an assembly shaft 57 extending upward around the predetermined region, and an adsorption releasing step of releasing the adsorption of the adsorption pad 74 when a lower surface of the separator 3 is brought into contact with an upper surface of another separator 3 that has been laminated in the predetermined region.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for assembling a fuel cell stack and a stacking device that can be used for assembling a fuel cell stack. [Background technology]

[0002] In recent years, technological developments related to fuel cells that contribute to energy efficiency have been underway to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. One known technology related to such fuel cells is a fuel cell stack assembly method in which separators are attracted to suction pads attached to the hands of a robot, and then the robot transports and stacks the separators in a predetermined position (see, for example, Patent Document 1). In the assembly method of Patent Document 1, the separators are positioned by being abutted against an abutting member, and then the suction is released and the separators are lowered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-287436 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method of releasing the suction and letting the separators fall freely as described in Patent Document 1, if the separators are warped or wavy, the stacking position may shift and they may get caught on assembly shafts or the like, making stacking difficult. [Means for solving the problem]

[0005] One aspect of the present invention is a method for assembling a fuel cell stack, which includes a lamination step of alternately laminating a membrane electrode assembly including an electrolyte membrane and an electrode and a separator in a predetermined region to form a cell laminate, wherein the membrane electrode assembly and the separator are both laminate elements, and the lamination step includes the steps of: Surrounded by a cylindrical body The method includes a transporting step of adsorbing the stack element via the adsorption section and transporting it above a predetermined area, a lowering step of positioning the stack element while lowering it along a guide member extending upward around the predetermined area, and an adsorption releasing step of releasing the adsorption of the adsorption section when the lower surface of the stack element abuts against the upper surface of another stack element already stacked in the predetermined area.

[0006] Another aspect of the present invention is a stacking device for stacking stack elements in a predetermined area to form a stack, the device comprising: Surrounded by a cylindrical body, Adsorb stack elements It was configured as The device includes a movable body having an adsorption portion and capable of being raised and lowered, a guide member extending upward around a predetermined region and regulating the position of the edge of the stack element when the movable body is lowered, an actuator that raises and lowers the movable body, and a control unit that controls the adsorption portion and the actuator. The control unit controls the actuator so that the movable body moves to a target position where the bottom surface of the stack element abuts on the top surface of another stack element that has already been stacked in the predetermined region, and controls the adsorption portion to release the adsorption of the stack element when the movable body moves to the target position. [Effects of the Invention]

[0007] According to the present invention, even if the separators are warped or wavy, the separators can be stacked with high precision without getting caught on shafts or the like used for assembly. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view schematically showing the overall configuration of a fuel cell stack to which a fuel cell stack assembly method according to an embodiment of the present invention is applied; [Figure 2A] FIG. 2 is a plan view of a separator included in the fuel cell stack of FIG. 1. [Figure 2B] FIG. 2 is a plan view of an electrode assembly included in the fuel cell stack of FIG. 1. [Figure 3] 1A and 1B are diagrams illustrating problems that arise when stacking separators. [Figure 4] 1 is a side view schematically showing a stacking device according to an embodiment of the present invention; [Figure 5] Arrow V view of Figure 4. [Figure 6] 5 is an enlarged cross-sectional view showing the main configuration of the suction pad of FIG. 4. [Figure 7A] FIG. 10 is a diagram showing a state in which the undulation of the separator has been corrected by suction with the suction pad. [Figure 7B] FIG. 10 is a diagram showing a state in which the warpage of the separator is corrected by suction with the suction pad. [Figure 8] FIG. 2 is a block diagram showing a control configuration of the stacking device according to the embodiment of the present invention. [Figure 9A] 9 is a flowchart showing an example of processing executed by the ECU of FIG. 8; [Figure 9B] FIG. 9B is a flowchart showing an example of processing following FIG. 9A. [Figure 10A] 5A to 5C are diagrams showing an example of an operation of the stacking device according to the embodiment of the present invention. [Figure 10B] FIG. 10B is a diagram showing an example of the operation following FIG. 10A. [Figure 10C] FIG. 10C is a diagram showing an example of the operation following FIG. 10B. [Figure 10D] FIG. 10D is a diagram showing an example of the operation following FIG. 10C. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 10D. FIG. 1 is a perspective view showing a schematic configuration of a fuel cell stack 100 assembled by a fuel cell stack assembly method according to an embodiment of the present invention. The fuel cell stack 100 constitutes a main element 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 mobile objects other than vehicles, such as aircraft and ships, robots, and various industrial machines.

[0010] In FIG. 1, three mutually orthogonal axial directions are shown as the X direction, the Y direction, and the Z direction for the sake of convenience. Y The direction is the stacking direction of the multiple power-generating cells 1 that make up the fuel cell stack 100, and corresponds to, for example, the front-to-rear direction, left-to-right direction, or up-and-down direction of the vehicle. As shown in Fig. 1, the fuel cell stack 100 has a cell stack 10, end units 20 arranged at both ends of the cell stack 10 in the Y direction, and a case 30 that surrounds the cell stack 10, and has a generally rectangular parallelepiped shape as a whole.

[0011] The case 30 has four side walls 300 facing the four side surfaces extending along the Y direction of the cell stack 10, and is configured in a generally box-like shape overall. Both end faces of the case 30 in the Y direction are open, and these open faces are covered with end units 20. Part A of FIG. 1 shows a cutaway view of a portion of the side wall 300 of the case 30. As shown in part A of FIG. 1, the cell stack 10 is configured by stacking multiple power-generating cells 1 (for convenience, only a single cell 1 is shown) in the Y direction.

[0012] The power-generating cell 1 has an electrode assembly 2 having an assembly including an electrolyte membrane and electrodes, and separators 3 arranged on both sides of the electrode assembly 2 in the Y direction and sandwiching the electrode assembly 2. The electrode assemblies 2 and the separators 3 are arranged alternately in the Y direction.

[0013] 2A is a plan view of separator 3. As shown in FIG. 2A, separator 3 has a pair of front and rear metal thin plates 31, 32 with a corrugated cross section, and is integrally formed by joining the outer peripheries of the pair of thin plates 31, 32. Separator 3 is made of a conductive material with excellent corrosion resistance, such as titanium, a titanium alloy, or stainless steel. The pair of thin plates 31, 32 are formed into an uneven shape by press molding or the like so as to form cooling channels inside separator 3 through which a coolant (e.g., water) flows, and the power generation surface of power generation cell 1 is cooled by the flow of the coolant.

[0014] By forming the surface of the thin plate 31 unevenly, an anode flow path through which fuel gas containing hydrogen flows along the X direction is formed between the thin plate 31 of the separator 3 and the electrode assembly 2. By forming the surface of the thin plate 32 unevenly, a cathode flow path through which oxidant gas containing oxygen flows along the X direction is formed between the thin plate 32 of the separator 3 and the electrode assembly 2.

[0015] A plurality of through holes 3a-3c and 3d-3f are aligned in the Z direction at one end and the other end of the separator 3 in the X direction. Resin tabs 35 are joined to the one end and the other end of the separator 3 in the Z direction by welding, brazing, or the like, and protrude from the edge of the separator 3 in one direction and the other in the Z direction. The tabs 35 are generally rectangular in plan view, and a through hole 35a is opened in the center thereof for positioning the separator 3 when stacked. The pair of tabs 35 are provided at different positions in the X direction.

[0016] FIG. 2B is a plan view of the electrode assembly 2. As shown in FIG. 2B, the electrode assembly 2 includes a membrane electrode assembly (MEA) 21 and a resin frame 22 that supports the periphery of the membrane electrode assembly. The membrane electrode assembly 21 includes an electrolyte membrane, an anode electrode provided opposite the anode flow path on one side of the electrolyte membrane in the Y direction, and a cathode electrode provided opposite the cathode flow path on the other side of the electrolyte membrane in the Y direction. The membrane electrode assembly 21 is sometimes referred to as a membrane electrode structure. The electrolyte membrane is, for example, a solid polymer electrolyte membrane. The anode electrode includes a catalyst layer formed on the surface of the electrolyte membrane and a gas diffusion layer formed outside the catalyst layer. The cathode electrode also includes a catalyst layer formed on the surface of the electrolyte membrane and a gas diffusion layer formed outside the catalyst layer.

[0017] At the anode electrode, fuel gas (hydrogen) supplied via the anode flow channel and gas diffusion layer is ionized by the action of a catalyst and moves through the electrolyte membrane to the cathode electrode. 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 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 electrode assembly 2.

[0018] At one end and the other end of the electrode assembly 2 in the X direction, a plurality of through-holes 2a-2c and 2d-2f are opened, aligned in the Z direction, penetrating the frame 22. The through-holes 2a-2f are provided so as to communicate with the through-holes 3a-3f of the separators, respectively. When forming the cell stack 10 (FIG. 1), a single electrode assembly 2 is integrally joined to a single separator 3 by welding, adhesive, or the like, to form a set of unit cells in advance. The unit cells are then stacked. Therefore, unlike the separators 3, the frame 22 of the electrode assembly 2 is not provided with tabs for positioning during stacking.

[0019] Each of the end units 20 on one side and the other side in the Y direction in FIG. 1 has a terminal plate arranged outside the cell stack 10 in the Y direction, an insulating plate arranged outside the terminal plate in the Y direction, and an end plate arranged outside the insulating plate in the Y direction. The terminal plate is a substantially rectangular metal plate-like member and has a terminal portion for extracting power generated by an electrochemical reaction in the cell stack 10. The insulating plate is a substantially rectangular metal plate-like member made of non-conductive resin or rubber, and electrically insulates the terminal plate from the end plate. The end plate is a metal or high-strength resin plate-like member.

[0020] The end unit 20 on one side in the Y direction has a plurality of through holes 20a-20c and 20d-20f lined up in the Z direction at one end and the other end in the X direction, penetrating the end unit 20. The through hole 20a is a through hole for supplying fuel gas into the inside of the cell stack 10. The through hole 20b is a through hole for discharging a coolant from the cell stack 10 to the outside. The through hole 20c is a through hole for discharging an oxidant gas from the cell stack 10 to the outside. The through hole 20d is a through hole for supplying an oxidant gas into the inside of the cell stack 10. The through hole 20e is a through hole for supplying a coolant into the cell stack 10. The through hole 20f is a through hole for discharging a fuel gas from the cell stack 10 to the outside.

[0021] Cell stack 10 X At both ends in the Y direction, a plurality of flow paths (manifolds) are formed that extend in the Y direction and communicate with the through holes 20a to 20f. These flow paths are formed by a collection of the through holes 3a to 3f and 2a to 2f in FIGS. 2A and 2B. Fuel gas and oxidant gas are introduced as reactant gases to the anode flow path and the cathode flow path inside the cell stack 10, respectively, via these flow paths, and power is generated in the power generation cell 1. A cooling medium is also introduced to the cooling flow path inside the cell stack 10, cooling the power generation surface. Although not shown, through holes are opened in the pair of end units 20 at positions corresponding to the through holes 35a in the tabs 35.

[0022] The method for assembling the fuel cell stack 100 configured as described above can be summarized as follows. First, the end unit 20 at one end in the Y direction is mounted on an assembly table along an assembly shaft that protrudes upward from the assembly table. Then, a predetermined number of separators 3 and electrode assemblies 2 are alternately stacked above the end unit 20 (stacking process). More specifically, a predetermined number of unit cells, each formed by joining a single separator 3 to a single electrode assembly 2, are stacked while positioning the unit cells by inserting the assembly shaft into the through-holes 35a of the tabs 35. At the end of the stacking process, the end unit 20 at the other end in the Y direction is stacked, thereby forming a pre-pressure stack.

[0023] Next, a pressure is applied from above to the stack using a pressurizer, shrinking the stack in the stacking direction (pressurizing process). When the length between the upper and lower end units 20 reaches a predetermined length, connecting members are fastened to the end units 20 using bolts so that the length between the end units 20 remains at the predetermined length while a compressive load is still applied to the stack. For example, both the upper and lower ends of the case 30 are fixed to the upper and lower end units 20 as connecting members (fastening process). This forms a cell stack 10 of a predetermined length. Next, the entire structure including the cell stack 10 is lifted, and the cell stack 10 is detached from the assembly shaft (detaching process). Finally, the through holes for the assembly shaft drilled in the end units 20 are blocked to seal the fuel cell stack 100 from the outside.

[0024] However, because the separator 3 is made of a thin plate, there is a risk that the entire separator may warp or undulate. There is also a risk that the tab 35 joined to the separator 3 may bend. In this case, as shown in FIG. 3 , the through-hole 35a of the tab 35 and the assembly shaft 57 are not parallel to each other, and therefore, during the stacking process, the through-hole 35a of the tab 35 may get caught on the assembly shaft 57, preventing smooth stacking (movement in the direction of arrow A) of the separator 3 (unit cells). Therefore, to enable smooth stacking of the unit cells, this embodiment is configured as follows.

[0025] The method for assembling the fuel cell stack 100 according to this embodiment is characterized in particular by the stacking process. The stacking of unit cells is carried out using a stacking device. FIG. 4 is a schematic diagram showing the overall configuration of a stacking device 50 according to an embodiment of the present invention. In the following, the up-down, left-right, and up-down directions are defined as shown in the figure, and the configuration of each part will be explained according to these definitions. The up-down direction is the direction of gravity, and corresponds to the Y direction (stacking direction) in FIG. 1. The left-right direction corresponds to the Z direction in FIG. 1.

[0026] As shown in Fig. 4, the stacking device 50 has an assembly table 55, a robot 60 that operates above the assembly table 55, a suction unit 70 attached to the robot 60, and a pair of left and right gripping devices 80 provided on the left and right sides of the assembly table 55. Fig. 4 shows a state in which the suction unit 70 is positioned above the gripping device 80 and a separator 3 is sucked by the suction unit 70. Note that hereinafter, the separators 3 to be stacked using the stacking device 50, i.e., the separators 3 to be stacked, may be referred to as workpieces.

[0027] The assembly table 55 has a base 56 disposed substantially horizontally and a pair of left and right assembly shafts 57 extending upward from the upper surface of the base 56. The assembly shafts 57 are substantially cylindrical, and the diameter of the upper end portion thereof gradually decreases as it extends upward. This allows the assembly shafts 57 to be easily inserted into the through-holes 35a of the tabs 35.

[0028] The robot 60 is an articulated industrial robot having arms 61 and 62 and a hand 63 attached to the tip of the arm 62. The arms 61 and 62 are rotatably connected via a rotation shaft 60a, and the arm 62 and hand 63 are rotatably connected via a rotation shaft 60b. The configuration of the robot 60 (such as the number of arms) is not limited to that shown in the figure. The arms 61 and 62 and the hand 63 are rotated by the drive of robot actuators such as servo motors attached to the rotation shafts 60a and 60b, thereby changing the position and posture of the hand 63. The robot actuators are controlled by an ECU (FIG. 8).

[0029] 5 is a view (view of arrow V in FIG. 4) of the suction unit 70 as seen from above. As shown in FIGS. 4 and 5, the suction unit 70 has a base plate 71 fixed to the hand 63, a movable plate 72 disposed below the base plate 71 and substantially parallel to the base plate 71, a plate support part 73 that supports the movable plate 72 from the base plate 71, and a plurality of suction pads 74 supported by the movable plate 72.

[0030] As shown in FIG. 5, the base plate 71 has a generally rectangular shape in a plan view, and its central portion is fixed to the hand 63. The movable plate 72 has a generally rectangular shape in a plan view that is slightly larger than the base plate 71, and both front and rear ends of the movable plate 72 protrude outward in the front-rear direction from the base plate 71, while both left and right ends of the movable plate 72 protrude outward in the left-right direction from the base plate 71. The shape of the peripheral portion of the movable plate 72 is substantially the same as the shape of the peripheral portion of the separator 3 (FIG. 2A). Therefore, both left and right ends of the movable plate 72 are provided with protruding portions 75 that protrude in the left-right direction, similar to the tabs 35 of the separator 3. Similar to the tabs 35, the protruding portions 75 are provided with through holes 75a in the up-down direction.

[0031] 4 and 5, the plate support parts 73 are provided near the four corners of the base plate 71. The plate support parts 73 have a case 731 that protrudes upward from the upper surface of the base plate 71, a rod 732 that passes through the base plate 71 and extends in the vertical direction, and a spring 733 that is interposed between the base plate 71 and the movable plate 72. The case 731 is a cylinder with a closed top surface and an open bottom surface.

[0032] The lower end of rod 732 is fixed to movable plate 72, and the upper end is inserted into case 731 so as to be movable up and down. Although not shown, plate support 73 is provided with movement limiters (downward movement limiter and upward movement limiter) that limit the upward and downward movement of rod 732 so that the upper end of rod 732 does not move outside case 731. The movement limiters can be configured, for example, by a rod-side protrusion protruding from the outer circumferential surface of rod 732 and two case-side protrusions protruding from the upper and lower portions of the inner circumferential surface of case 731. That is, by arranging the rod-side protrusion between the upper and lower case-side protrusions and abutting the rod-side protrusion against the case-side protrusion, the vertical movement of rod 732 can be limited. Initially, rod 732 is pulled downward by the gravity of movable plate 72, reaching its maximum downward movement within the case at the initial abutting position. The configuration of the movement limiters is not limited to the above.

[0033] Spring 733 is, for example, a coil spring (more specifically, a compression coil spring) provided to surround rod 732. The lower end surface of spring 733 abuts against the upper surface of movable plate 72, and the upper end surface abuts against the lower surface of base plate 71. As a result, movable plate 72 is supported by base plate 71 via spring 733 so as to be able to move up and down, and base plate 71 and movable plate 72 can approach each other by retracting spring 733.

[0034] 5, the suction pads 74 are attached to the underside of the movable plate 72 on the outer sides in the front-rear direction and the outer sides in the left-right direction of the base plate 71. More specifically, a plurality of suction pads 74 are provided side by side in the left-right direction at both front-rear end portions of the movable plate 72, and a pair of suction pads 74 are provided on the front and rear of the protruding portion 75, sandwiching a through-hole 75a therebetween. The arrangement of the suction pads 74 is not limited to this, and additional suction pads 74 may be provided on both left and right end portions of the movable plate 72 (other than the protruding portion 75).

[0035] Fig. 6 is a cross-sectional view showing a schematic configuration of the suction pad 74. As shown in Fig. 6, the suction pad 74 has a substantially cylindrical pad portion 741 and a substantially ring-shaped pad support portion 742 to which the upper end of the pad portion 741 is fixed. The pad portion 741 is made of an elastic material such as rubber or resin. The pad support portion 742 is made of, for example, metal.

[0036] A substantially cylindrical metal pipe 76 is arranged around the suction pad 74 so as to surround the suction pad 74. The outer circumferential surface of the pipe 76 is stepped, and a threaded portion is provided on the outer circumferential surface of the upper side of the pipe 76. A through hole 72a is opened in the movable plate 72. The through hole 72a is, for example, a threaded hole, and the upper end of the pipe 76 screws into the threaded hole and protrudes upward from the through hole 72a. A nut 761 screws into the outer circumferential surface of the pipe 76, thereby fixing the pipe 76 to the movable plate 72. A piping 77 is connected to the upper end of the pipe 76 via a joint (not shown).

[0037] The pad support portion 742 of the suction pad 74 is airtightly fixed to the inner peripheral surface of the pipe 76. For example, threads are provided on the outer peripheral surface of the pad support portion 742 and the inner peripheral surface of the pipe 76, and after the pad support portion 742 is screwed to a predetermined position, the peripheral surface is sealed and the pad support portion 742 is fixed to the pipe 76. The pad support portion 742 may be fixed to the inner peripheral surface of the pipe 76 by welding or the like, or may be fixed to the inner peripheral surface via a sealing material. The upper end of the pipe 76 may be fixed to the lower surface of the movable plate 72 without passing through the through hole 72a. In this case, the pad support portion 742 may be configured to pass through the through hole 72a of the movable plate 72, and the upper end of the pad support portion 742 may be fixed to the movable plate 72 via a nut 761 or the like.

[0038] The outer circumferential surface of the pad portion 741 of the suction pad 74 has a smaller diameter than the outer circumferential surface of the pad support portion 742, and there is a gap between the outer circumferential surface of the pad portion 741 and the inner circumferential surface of the pipe 76. The lower end surface of the pad portion 741 is a suction surface 741a, which is located on the same plane as the lower end surface (tip surface) 76a of the pipe 76. An internal passage 74a is provided inside the suction pad 74, running vertically through the entire suction pad from the upper end surface of the pad support portion 742 to the suction surface 741a. The internal passage 74a communicates with the vacuum generator via the pipe 76 and piping 77.

[0039] When the vacuum generator is turned on and the internal passage 74a is in a vacuum state, an adsorption force acts on the workpiece (separator 3), allowing the workpiece to be adsorbed. When the vacuum generator is turned off, the adsorption force is removed, allowing the workpiece to be released from the adsorption surface. Turning the vacuum generator on and off involves opening and closing a solenoid valve installed in the flow path connecting the vacuum generator and the internal passage 74a. Turning the vacuum generator on and off (for example, opening and closing the solenoid valve) is controlled by the ECU (Figure 8).

[0040] In this embodiment, a metal pipe 76 is provided around the suction pad 74, so that when the separator 3 (workpiece) is sucked by the suction pad 74, any warping or undulation of the separator 3 can be corrected. For example, as shown in FIG. 7A , if the separator 3 is undulated, when the upper end surface of the tab 35 is sucked by the suction pad 74, the suction force causes the upper end surface of the tab 35 to come into close contact with the entire lower end surface 76a of the pipe 76. Also, as shown in FIG. 7B , even if the separator 3 is warped, when the upper end surface of the tab 35 is sucked by the suction pad 74, the suction force causes the upper end surface of the tab 35 to come into close contact with the entire lower end surface 76a of the pipe 76.

[0041] This straightens out any warping or undulation of the separator 3, and positions the upper end surfaces of the left and right tabs 35 on the same horizontal plane. As a result, the separator 3 assumes a uniformly horizontal position overall. This allows the assembly shaft 57 to be smoothly inserted from above into the through-hole 35a of the tab 35 of the separator 3, unlike FIG. 3. As shown in FIG. 5, the suction pads 74 are provided on the periphery of the movable plate 72, and a pair of suction pads 74 are provided close to each other at positions corresponding to the tabs 35 of the separator 3, sandwiching the through-hole 75a therebetween. This allows a strong straightening force to be applied to the tabs 35 to position them horizontally, and reliably prevents the through-hole 35a from getting caught on the assembly shaft 57.

[0042] As shown in Fig. 4, each of the pair of left and right grip devices 80 has an upper grip 81 and a lower grip 82 arranged a predetermined distance L1 below the upper grip 81. The upper grip 81 and the lower grip 82 have the same configuration. Fig. 5 shows a plan view of the pair of left and right upper grips 81 as the grip device 80. The plan view of the lower grip 82 is also the same as that shown in Fig. 5.

[0043] As shown in FIG. 5, the grip device 80 includes a bracket 83 fixedly disposed on the outer side of the suction unit 70 in the left-right direction, and a pair of front and rear levers 84 protruding inward in the left-right direction from the bracket 83. The lever 84 has a generally rectangular parallelepiped shape and is rotatably supported on an end of the bracket 83 via a pin 85 extending in the vertical direction. The solid line in FIG. 5 indicates the closed position (closed posture) of the lever 84. In the closed position, the end faces 84b of the pair of levers 84 abut against each other. The end faces 84b are gripping surfaces that grip the assembly shaft 57 (FIG. 4), and the gripping surfaces 84b are provided with recesses 84a that are generally semicircular or triangular in shape extending in the vertical direction, corresponding to the position and shape of the assembly shaft 57. In the closed position, the assembly shaft 57 is sandwiched and held between the inner sides of the pair of recesses 84a.

[0044] The two-dot chain line in FIG. 5 indicates the open position (open posture) of the levers 84. In the open position, the pair of levers 84 rotates approximately 90° outward in the front-rear direction from the closed position. This separates the levers 84 from the assembly shaft 57, and the levers 84 retract further outward in the left-right direction than the outer end faces of the protrusions 75 in the left-right direction. As a result, the suction unit 70 can be raised and lowered without interfering with the gripping device 80. The levers 84 rotate (open and close) by driving a gripping actuator. The gripping actuator is an actuator such as a pneumatic cylinder that rotates the levers 84 between the closed position and the open position. The gripping actuator is controlled by the ECU (FIG. 8).

[0045] Fig. 8 is a block diagram showing the control configuration of the stacking device 50. As shown in Fig. 8, the stacking device 50 has an ECU 90, an angle sensor 91, a robot actuator 92, a gripping actuator 93, and a vacuum generator 94, each of which is communicatively connected to the ECU 90.

[0046] The angle sensor 91 is a sensor that detects the rotation angle of the rotation axes 60a and 60b of the robot 60, and is configured by a rotary encoder or a resolver. The position and posture of the hand 63 can be detected (calculated) based on the signal from the angle sensor 91, and thereby the position and posture of the base plate 71 integrated with the hand 63 can be detected.

[0047] The ECU 90 is an electronic control unit including a computer having a CPU, a ROM, a RAM, and other peripheral circuits. unit the current position of the suction pad 74, for example, 741a The position of the adsorption surface is detected (calculated). 741a Based on the current positions of the robot 90 and the gripping actuator 93, the robot controller 91 controls the robot actuator 92 and the gripping actuator 93, and turns on or off the vacuum generator 94. The on / off control of the vacuum generator 94 includes the opening and closing control of an electromagnetic valve provided in the middle of the flow path connecting the vacuum generator 94 and the internal passage 74a of the suction pad 74.

[0048] Adsorption surface 741a Regarding the position detection, the ECU 90 stores in advance in its memory the hand 63 of the robot 60 and the suction surface 741a The ECU 90 then stores the positional relationship between the hand 63 and the suction surface 74a (the relative distances in the three axial directions from the hand 63 to the suction surface 74a). 63 The three-dimensional position of the object from the reference point (for example, the center point of the upper surface of the base 56) is calculated, and the distance from the hand 63 to the suction surface, which is stored in advance at this three-dimensional position, is calculated. 741a By adding the relative distance to the reference point, the attraction surface 741a That is, the initial position where the rod 732 moves downward to the maximum extent inside the case 731. 741a At the position of the base 56, 741a Includes the height up to

[0049] 9A and 9B are flowcharts showing an example of processing executed by the ECU 90 in accordance with a predetermined program. The processing shown in this flowchart is started, for example, after the end unit 20 is mounted on the upper surface of the base 56, when a command is issued to start stacking unit cells (a set of electrode assemblies 2 and separators 3), and is repeated until a predetermined number of unit cells have been stacked. At the initial point when the processing starts, the upper grip 81 of the gripping device 80 is open and the lower grip 82 is closed. Also, at the initial point, the suction unit 70 is located in an initial position. At the initial position, the suction unit 70 is located above a tray (not shown) in which unit cells to be stacked are stored.

[0050] As shown in FIG. 9A, the ECU 90 first turns on the vacuum generator 94 in step S1. This causes a suction force to act on the suction pad 74, and the separator 3 (unit cell) is suctioned. More specifically, the separator 3 is suctioned with the position of the through-hole 75a of the protrusion 75 of the movable plate 72 aligned with the position of the through-hole 35a of the tab 35 of the separator 3. At this time, the upper surface of the separator 3 (such as the upper end surface of the tab 35) comes into close contact with the lower end surface 76a of the pipe 76, thereby straightening out any undulations or warping of the separator 3 (FIGS. 7A and 7B). This allows the entire separator to be held in a horizontal position.

[0051] Next, in step S2, the ECU 90 outputs a control signal to the robot actuator 92, and adjusts the suction unit 70 (for example, the suction surface 70) based on the signal from the angle sensor 91. 741a 4. At the descent start position, the through-hole 35a of the tab 35 of the separator 3 that has been picked up is positioned above the assembly shaft 57. More precisely, the center lines of the through-hole 35a and the through-hole 75a are positioned on an extension of the center line of the assembly shaft 57. Next, in step S3, the ECU 90 outputs a control signal to the robot actuator 92, and while grasping the current position of the suction unit 70 based on the signal from the angle sensor 91, moves the suction unit 70 (suction pad 74) in the front-rear and rear directions. left and right The suction unit 70 is lowered while maintaining the position in the direction constant (lowering step).

[0052] 10A, the separator 3 (strictly speaking, a unit cell integrated with the electrode assembly 2) moves in the direction of arrow A1, and the separator 3 descends along the assembly shaft 57 while the assembly shaft 57 is inserted into the through-hole 35a of the tab 35 of the separator 3. At this stage, the assembly shaft 57 is held by the lower grip 82, preventing the long assembly shaft 57 from bending. Therefore, the through-hole 35a of the separator 3 does not get caught on the assembly shaft 57, and the separator 3 can descend smoothly. In addition, because the lever 84 of the upper grip 81 is in the open position, the separator 3 can descend to below the upper grip 81 without interfering with the upper grip 81.

[0053] Next, in step S4, the ECU 90 determines whether or not the suction unit 70 has reached a predetermined position based on a signal from the angle sensor 91. In other words, as shown in FIG. 10B, the ECU 90 741a ) has reached a predetermined position, which is a predetermined height H1 above the base 56. The predetermined position is a position where the separator 3 is below the upper grip 81 and above the lower grip 82. At the predetermined position, the upper and lower grips 81, 82 can be opened and closed without interfering with the separator 3 or the suction unit 70. If the answer to step S4 is negative, the process returns to step S3, and the suction unit 70 continues to descend. If the answer to step S4 is positive, the process proceeds to step S5.

[0054] In step S5, the ECU 90 outputs a control signal to the robot actuator 92 to stop the descent of the suction unit 70. Next, in step S6, the ECU 90 outputs a control signal to the grip actuator 93 of the upper grip 81 to move the lever 84 of the upper grip 81 to the closed position as shown in Fig. 10B (moving step). Next, in step S7, the ECU 90 outputs a control signal to the grip actuator 93 of the lower grip 82 to move the lever 84 of the lower grip 82 to the open position as shown in Fig. 10B (moving step).

[0055] Next, in step S8, the ECU 90 outputs a control signal to the robot actuator 92, and while grasping the current position of the suction unit 70 based on the signal from the angle sensor 91, adjusts the forward / backward and rearward directions of the suction unit 70 (for example, the suction pad 74). left and right The suction unit 70 is lowered while keeping the position in the direction constant. As a result, the separator 3 descends along the assembly shaft 57, as shown by arrow A2 in FIG. 10B. At this stage, the assembly shaft 57 is held by the upper grip 81, so bending of the long assembly shaft 57 is prevented. Therefore, the through-hole 35a of the separator 3 does not get caught on the assembly shaft 57, and the separator 3 can descend smoothly. Furthermore, because the lever 84 of the lower grip 82 is in the open position, the separator 3 can descend to below the lower grip 82 without interfering with the lower grip 82, as shown in FIG. 10C.

[0056] Next, in step S9, the ECU 90 determines whether the suction unit 70 has reached the target position based on a signal from the angle sensor 91, i.e., whether the separator 3 has reached the target position by moving in the direction of arrow A3 in Fig. 10C. The target position corresponds to the upper surface position of the already stacked stack 10A (a stack before the stacking process is completed, and this is referred to as the unfinished stack) as shown in Fig. 10D, and is a position that is a target height H2 above the base 56. The ECU 90 calculates the target height H2 and the target position based on the number of separators 3 that have already been stacked (the number of unfinished stacks 10A) and taking into consideration the overall amount of crushing of the unfinished stack 10A due to gravity.

[0057] More specifically, the thickness of each separator 3 (strictly speaking, the thickness of each set of unit cells) is stored in advance in the memory of the ECU 90, as well as the relationship between the number of stacked separators 3 and the crushing amount. Using this relationship, the target height H2 is calculated. The target height H2 increases each time a separator 3 is stacked.

[0058] Because there is an error in the thickness of the separator 3, the calculated target position may differ from the actual position of the top surface of the uncompleted stack 10A. In this case, there is a risk that the top surface of the uncompleted stack 10A will be pressed by the robot 60 via the separator 3 sucked by the suction pad 74. In this case, the spring 733 between the base plate 71 and the movable plate 72 is contracted. This prevents excessive pressure load from being applied to the suction pad 74, the separator sucked by the suction pad 74, and the uncompleted stack 10A. Furthermore, because the spring 733 can absorb the error in the thickness of the separator 3, there is no need for the ECU 90 to accurately calculate the target position.

[0059] If the result of step S9 is negative, the process returns to step S8, and the suction unit 70 continues to descend. If the result of step S9 is positive, the process proceeds to step S10. In step S10, the ECU 90 outputs a control signal to the vacuum generator 94 to turn off the vacuum generator 94. This releases the suction of the separator 3 by the suction pad 74 (suction release process). In this case, the suction is released after the separator 3 abuts on the upper surface of the pre-completion stack 10A, so the separator 3 does not fall freely, and can be stacked well on the upper surface of the pre-completion stack 10A with the separator 3 positioned accurately. The processes of steps S1 to S10 above are the processes up to stacking the separators 3 (unit cells).

[0060] Next, the process proceeds to step S11 in FIG. 9B, where a process of returning the suction unit 70 to its initial position is started. In step S11, the ECU 90 outputs a control signal to the robot actuator 92 to raise the suction unit 70. At this time, the lever 84 of the lower grip 82 is in the open position, so the suction unit 70 can move up to above the lower grip 82 without interfering with the lower grip 82. Next, in step S12, it is determined whether the suction unit 70 has reached a predetermined position. This determination is the same as that in step S4, and the predetermined position is set to a position between the upper grip 81 and the lower grip 82. If a negative determination is made in step S12, the process proceeds to step S11, where the suction unit 70 continues to rise. If a positive determination is made in step S12, the process proceeds to step S13.

[0061] In step S13, the ECU 90 outputs a control signal to the robot actuator 92 to stop the lifting of the suction unit 70. Next, in step S14, the ECU 90 outputs a control signal to the grip actuator 93 of the lower grip 82 to move the lever 84 of the lower grip 82 to the closed position. Next, in step S15, the ECU 90 outputs a control signal to the grip actuator 93 of the upper grip 81 to move the lever of the upper grip 81 to the closed position. At this time, the movable plate 72 is positioned between the lower grip 82 and the upper grip 81, and therefore the grips 81, 82 can be opened and closed without interference between the movable plate 72 and the upper and lower grips 81, 82.

[0062] Next, in step S16, the ECU 90 outputs a control signal to the robot actuator 92 to raise the suction unit 70. At this time, the lever 84 of the upper grip 81 is in the open position, so the suction unit 70 (movable plate 72) can rise without interfering with the upper grip 81. Next, in step S17, the ECU 90 determines whether the suction unit 70 has risen to a predetermined detachment position based on a signal from the angle sensor 91. The detachment position is a position where the movable plate 72 moves above the upper end of the assembly shaft 57 and the through-hole 75a detaches from the assembly shaft 57. The detachment position may be set to the same position as the descent start position in step S2.

[0063] Next, in step S18, the ECU 90 outputs a control signal to the robot actuator 92 to move the suction unit 70 to its initial position above the tray. This completes one cycle of the stacking process. Thereafter, the same process is repeated until a predetermined number of separators 3 (unit cells) are stacked.

[0064] According to this embodiment, the following effects can be achieved. (1) The method for assembling a fuel cell stack includes a stacking step in which electrode assemblies 2 (membrane electrode structures) each including an electrolyte membrane and an electrode and separators 3 are alternately stacked on a base 56 in a predetermined region to form a cell stack 10. The stacking step includes a transport step (step S2) in which separators 3 (strictly speaking, unit cells each integrally provided with an electrode assembly 2) are suction-attached via suction pads 74 and transported above the predetermined region; a lowering step (step S3) in which separators 3 are lowered while being positioned along an assembly shaft 57 extending upward around the predetermined region; and a suction release step (step S10) in which suction by suction pads 74 is released when the lower surface of separator 3 abuts against the upper surface of another stack element (pre-completion stack 10A) already stacked in the predetermined region (FIG. 9A). In this assembly method, rather than allowing separator 3 to freely fall along assembly shaft 57, robot 60 transports separator 3 until it abuts against the upper surface of pre-completion stack 10A. Therefore, even if the separators 3 are warped or wavy, the stacking positions of the separators 3 do not shift, and the cell stack 10 can be formed with high precision.

[0065] (2) The stacking step further includes a moving step (steps S6 and S7) in which the levers 84 of the upper grip 81 and the lower grip 82 constituting the pair of upper and lower grip devices 80 are moved in accordance with the lowered position of the separator 3 in the lowering step. The levers 84 are movable between a closed position (first position) that holds the assembly shaft 57 and an open position (second position) that separates the assembly shaft 57 (FIG. 9A). In the moving step, the lever 84 of the upper grip 81 is moved to the open position, and the lever 84 of the lower grip 82 is moved to the closed position until the separator 3 descends to a predetermined position between the upper grip 81 and the lower grip 82. Then, when the separator 3 descends to the predetermined position, the lever 84 of the upper grip 81 is moved to the closed position, and the lever 84 of the lower grip 82 is moved to the open position (FIG. 9A). As a result, the long assembly shaft 57 is held by at least one of the upper grip 81 and the lower grip 82 when the separator 3 descends along the assembly shaft 57. Therefore, bending of the assembly shaft 57 can be prevented, and the separator 3 can be smoothly lowered along the assembly shaft 57 to the target position.

[0066] (3) In the lowering step, the separator 3 is lowered while the suction pad 74 is supported by the base plate 71, which is moved by the drive of the robot actuator 92, via the spring 733 that can contract in the vertical direction (FIG. 10D). This prevents the robot 60 that transports the separator 3 from applying an excessive load to the unfinished stack 10A. Therefore, even if there is an error in the stacking position of the separator 3, the separator 3 can be lowered successfully to the target position.

[0067] (4) The stacking device 50 is configured to stack separators 3 on a base 56 in a predetermined region to form a cell stack 10. The stacking device 50 includes a suction unit 70 that is movable up and down and has suction pads 74 that suction-adsorb the separators 3; an assembly shaft 57 that extends upward around the periphery of the predetermined region and regulates the position of the edge of the separator 3 when the suction unit 70 is lowered; a robot actuator 92 that raises and lowers the suction unit 70 via a robot 60; a vacuum generator 94 that enables suction by the suction pads 74; and an ECU 90 that controls the vacuum generator 94 and the robot actuator 92 (FIGS. 4 and 8). The ECU 90 controls the robot actuator 92 so that the suction unit 70 moves to a target position where the bottom surface of the separator 3 abuts against the top surface of another stack element (pre-finished stack 10A) that has already been stacked in the predetermined region, and controls the vacuum generator 94 to release suction from the separator 3 when the suction unit 70 moves to the target position (FIG. 9A). As a result, even if the separators 3 are warped or wavy, the separators 3 are not misaligned and the cell stack 10 can be formed with high precision.

[0068] (5) The stacking device 50 further includes an upper grip 81 and a lower grip 82 constituting a pair of upper and lower grip devices 80 each having a lever 84 movable between a closed position that holds the assembly shaft 57 and an open position that moves the lever 84 away from the assembly shaft 57, a grip actuator 93 that drives the upper grip 81 and the lower grip 82 to open and close, and an angle sensor 91 that detects the lowered position of the separator 3 ( FIG. 8 ). The ECU 90 further controls the grip actuator 93 to move the lever 84 of the upper grip 81 to the open position and the lever 84 of the lower grip 82 to the closed position until the lowered position of the separator 3 detected by the angle sensor 91 reaches a predetermined position between the upper grip 81 and the lower grip 82, and when the predetermined position is reached, to move the lever 84 of the upper grip 81 to the closed position and the lever 84 of the lower grip 82 to the open position ( FIG. 9A ). This prevents the assembly shaft 57 from bending when the separator 3 is lowered along the assembly shaft 57, and allows the separator 3 to be mounted accurately on the top surface of the unfinished laminate 10A.

[0069] (6) The suction unit 70 further includes a base plate 71 that moves up and down when driven by a robot actuator 92, and a plate support portion 73 that supports the suction pad 74 from the base plate 71 via a spring 733 so that the suction pad 74 can move relatively up and down (FIG. 4). This prevents an excessive load from being applied to the uncompleted laminate 10A when the separator 3 is mounted on the top surface of the uncompleted laminate 10A using the robot 60.

[0070] (7) The stacking device 50 further includes a pipe 76 having a lower end surface 76a that extends in the same plane as the suction surface 741a of the suction pad 74 and that surrounds the suction pad 74 (FIG. 6). This allows the separator 3 to be lowered along the assembly shaft 57 while any warping or undulation of the separator 3 is corrected, allowing for a smooth lowering movement of the separator 3.

[0071] The above-described embodiment can be modified in various ways. In the above-described embodiment, the electrode assembly 2 (membrane electrode structure) and the separator 3 are integrated in advance to form a unit cell, and then the separator 3 is attracted to the electrode assembly 2. However, the electrode assembly 2 and the separator 3 may be attracted to each other alternately without being integrated to the electrode assembly 2 and the separator 3. That is, either one of the membrane electrode structure and the separator as the stacked element or both may be attracted to the electrode assembly 2 and the separator 3. In the above-described embodiment, the ECU 90 controls the on / off of the vacuum generator 94 to control the operation of the suction pad 74 as the suction unit. That is, although the ECU 90 and the vacuum generator 94 are used as a control unit for controlling the suction unit, the configuration of the control unit is not limited thereto.

[0072] In the above embodiment, the assembly shaft 57 serving as the guide member is erected from the upper surface of the base 56, but it may be erected from the lower end unit 20. In this case, the guide member may be pulled out from above after the pressurizing step or the fastening step. In the above embodiment, the assembly shaft 57 is configured to have a substantially cylindrical shape and is inserted into the through-hole 35a of the tab 35 of the separator 3. However, the guide member is not limited to a cylindrical shape as long as it regulates the position of the edge of the separator. For example, the edge of the separator 3 may be provided with a recess or protrusion, and the guide member may be configured to engage with this. The guide member may be projected upward from the upper surface of the end unit 20 and stored within the case 30 as an element of the fuel cell stack 100.

[0073] In the above embodiment, the assembly shaft 57 is erected around the base 56, and the separators 3 and other laminate elements are stacked on the base, but the predetermined area where the stacking process is performed is not limited to the above. In the above embodiment, the suction unit 70 is provided so that it can be raised and lowered, but the configuration of the movable body having the suction part is not limited to the above. In the above embodiment, the suction unit 70 is transported and raised and lowered by the robot actuator 92, but it may be transported and raised and lowered without the robot 60, and the configuration of the actuator (first actuator) that raises and lowers the movable body is not limited to the above.

[0074] In the above embodiment, a pair of upper and lower grip devices 80 having openable and closable levers 84 are configured as guide support portions. That is, the upper grip 81 and the lower grip are configured as upper and lower guide support portions, respectively, but the configuration of the guide support portions is not limited to the above. Therefore, the first position does not have to be the closed position of the lever 84, and the second position does not have to be the open position of the lever 84. The configuration of the grip actuator 93 (second actuator) is also not limited to the above.

[0075] In the above embodiment, the lowered position of the separator 3 is detected based on a signal from the angle sensor 91, but the lowered position may be detected using other sensors, and the configuration of the position detection unit is not limited to this. In the above embodiment, the suction pad 74 is supported via the plate support unit 73 so as to be relatively movable from the base plate 71. That is, the suction pad 74 is supported via the base plate 71 (base unit) of the suction unit 70 via the spring 733 as an elastic body so as to be relatively movable in the up and down direction, but the configuration of the support unit is not limited to this. In the above embodiment, the pipe 76 is provided so as to surround the suction pad 74, but the configuration of the cylinder is not limited to the above.

[0076] In the above embodiment, the stacking device 50 is used to construct the cell stack 10 of the fuel cell stack 100, but the stacking device of the present invention can also be applied to constructing other stacks by stacking stack elements while positioning them.

[0077] 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.

[0078] 2 electrode assembly, 3 separator, 10 cell stack, 35 tab, 35a through hole, 50 stacking device, 56 base, 57 assembly shaft, 70 suction unit, 71 base plate, 73 plate support, 74 suction pad, 76 pipe, 90 ECU, 91 angle sensor, 92 robot actuator, 93 grip actuator, 94 vacuum generator, 100 fuel cell stack, 733 spring

Claims

1. A method for assembling a fuel cell stack, comprising a lamination step of alternately laminating separators and membrane electrode assemblies each including an electrolyte membrane and an electrode in a predetermined region to form a cell stack, the membrane electrode assembly and the separator are both laminate elements; The lamination step includes: a conveying step of suctioning the stacked element via a suction portion surrounded by a cylindrical body and conveying the stacked element above the predetermined area; a lowering step of lowering the stack element while positioning it along a guide member extending upward around the predetermined area; and an adsorption release step of releasing the adsorption of the adsorption portion when the lower surface of the stack element abuts against the upper surface of another stacked stack element in the predetermined region.

2. 2. The method for assembling a fuel cell stack according to claim 1, the stacking step further includes a moving step of moving an upper guide support part and a lower guide support part, which are a pair of upper and lower guide support parts that are movable between a first position that holds the guide member and a second position that is spaced apart from the guide member, in accordance with the lowering position of the stacked body elements in the lowering step; The method for assembling a fuel cell stack includes, in the moving process, moving the upper guide support portion to the second position and the lower guide support portion to the first position until the stack element descends to a predetermined position between the upper guide support portion and the lower guide support portion, and when the stack element descends to the predetermined position, moving the upper guide support portion to the first position and the lower guide support portion to the second position.

3. 3. The method for assembling a fuel cell stack according to claim 1 or 2, The lowering step includes lowering the stack element while supporting the suction portion via an elastic body that can contract in the vertical direction on a base portion that moves by driving an actuator.

4. A stacking device for stacking stack elements in a predetermined area to form a stack, a movable body that is surrounded by a cylindrical body, has an adsorption part configured to adsorb the stacked body element, and is provided so as to be able to move up and down; a guide member extending upward around the predetermined region and regulating the position of an edge of the stack element when the movable body is lowered; an actuator that raises and lowers the movable body; a control unit that controls the suction unit and the actuator, The control unit controls the actuator so that the movable body moves to a target position where the lower surface of the laminate element abuts the upper surface of another laminate element that has already been stacked in the specified area, and controls the suction unit so that the suction of the laminate element is released when the movable body moves to the target position.

5. The stacking device according to claim 4, the actuator is a first actuator; an upper guide support portion and a lower guide support portion, which are a pair of upper and lower guide support portions provided to be movable between a first position that holds the guide member and a second position that is spaced apart from the guide member; a second actuator that drives the upper guide support portion and the lower guide support portion; a position detection unit that detects the lowering position of the stacked element, The control unit is further characterized in that the control unit controls the second actuator to move the upper guide support unit to the second position and the lower guide support unit to the first position until the lowered position of the stack element detected by the position detection unit reaches a predetermined position between the upper guide support unit and the lower guide support unit, and when the predetermined position is reached, to move the upper guide support unit to the first position and the lower guide support unit to the second position.

6. 6. The stacking device according to claim 4 or 5, The stacking device is characterized in that the movable body further has a base portion that rises and falls by driving the actuator, and a support portion that supports the suction portion so that it can move relatively in the vertical direction from the base portion via an elastic body.

7. 6. The stacking device according to claim 4 or 5, The stacking device is characterized in that the cylindrical body has a tip surface that extends on the same plane as the suction surface of the suction portion.

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