Fuel cell stack and method for assembling a fuel cell stack

Abstract

To provide a method for assembling a fuel cell stack that allows cells to be easily stacked after a case is attached.SOLUTION: A method for assembling a fuel cell stack includes the steps of holding an insulating plate 22 disposed above an end plate 23 via a rod 203 that is movable in the vertical direction relative to a table 202, and stacking a power generating cell 1 on the insulating plate 22 to form a cell stack. The holding step includes a step of abutting the upper end of the rod 203 that has passed through the through hole 230 of the end plate 23 against the peripheral surface of the through hole 220 of the insulating plate 22 to hold the insulating plate 22.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a fuel cell stack and a method for assembling a fuel cell stack. [Background technology]

[0002] In recent years, technological developments have been made 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 fuel cell stack that constitutes such a fuel cell is generally assembled by stacking a plurality of power generation cells after end plates, insulators, terminal plates, etc. are sequentially mounted on the top surface of an assembly table. In this regard, a device that stacks the power generation cells while positioning them along positioning pins erected from the end plates is known (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7174789 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a case that surrounds the stack is attached to the end plate, but the device described in Patent Document 1 above is configured so that the power generation cells are stacked without the case, and it is difficult to stack the power generation cells in the space within the case after the case is attached because the case becomes an obstacle. [Means for solving the problem]

[0005] A fuel cell stack according to one aspect of the present invention includes a cell stack formed by alternately stacking a membrane electrode assembly including an electrolyte membrane and an electrode and a separator, a housing surrounding the cell stack, and an end unit disposed at an end of the cell stack in a stacking direction, and a guide member attached to the inner surface of the housing and extending in the stacking direction. The cell stack is formed by stacking unit stacks, which are assemblies of a membrane electrode assembly and a separator that have been previously joined together, and the separator has an engagement portion that engages with the guide member.The end unit has an end plate fixed to an end of the housing, and an intermediate plate disposed between the end plate and the cell stack. The end plate and the intermediate plate are each provided with a plurality of communication holes that penetrate the end plate and the intermediate plate in a direction parallel to the stacking direction and are used to supply reactant gas and cooling medium to the cell stack and discharge them from the cell stack. The communication holes in the intermediate plate are smaller than the communication holes in the end plates. The intermediate plate has an abutment portion against which a tip end of a rod member abuts against a peripheral surface of the communication hole so that the intermediate plate is supported so as to be movable up and down by a rod member that passes through the communication hole of the end plate mounted on an assembly table during assembly or disassembly of the fuel cell stack.

[0006] Another aspect of the present invention is a method for assembling a fuel cell stack in which a stacking direction is vertical, the method comprising the steps of: mounting a lower end plate on an upper surface of an assembly table and fixing a lower end of a case to the lower end plate; inserting a guide member through an opening at the top end of the case and attaching the guide member to an inner surface of the case; The method includes a holding step of holding an intermediate plate, which is placed above the lower end plate, at a cell stacking position above the lower end plate via a rod member that is movable in a vertical direction relative to an assembly table; a stacking step of alternately stacking a membrane electrode structure including an electrolyte membrane and an electrode and a separator on the intermediate plate held via the rod member to form a cell stack; a lowering step of lowering the intermediate plate by moving the rod member downward and placing it on the upper surface of the lower end plate; and a pressurizing step of pressing the cell stack from above via the upper end plate to fix the upper end plate to the upper end of the case. the lamination step includes forming a unit laminate by previously joining a membrane electrode assembly and a separator, and laminating the unit laminate while engaging an engaging portion provided on the separator with a guide member to form a cell laminate; The lower end plate and the intermediate plate are each provided with a plurality of communication holes that vertically penetrate the lower end plate and the intermediate plate, respectively, for supplying reactant gas and cooling medium to the cell stack and discharging them from the cell stack. The communication holes in the intermediate plate are smaller than the communication holes in the lower end plate. The holding step includes abutting an upper end of a rod member that has passed through the communication hole in the lower end plate against a peripheral surface of the communication hole in the intermediate plate to hold the intermediate plate in the cell stacking position. Effect of the Invention

[0007] According to the present invention, after the case is attached, the power generating cells can be easily stacked in the space within the case. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a schematic overall configuration of a fuel cell stack according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] 1 is a diagram showing a schematic configuration of an assembly device used in a fuel cell stack assembly method according to an embodiment of the present invention; [Figure 5A] FIG. 5 is an enlarged view of the main configuration of FIG. 4. [Figure 5B] Arrow VB view of Figure 5A. [Figure 6A] FIG. 5B is a diagram showing a modification of FIG. 5A. [Figure 6B] FIG. 5B is a diagram showing another modified example of FIG. 5A. [Figure 7] FIG. 5 is a diagram showing a reference example of FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 7. A fuel cell stack according to an embodiment of the present invention 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 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. FIG. 1 is a perspective view showing the overall configuration of a fuel cell stack 100 according to an embodiment of the present invention. In the following, for convenience, three mutually orthogonal axial directions as 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 according to these definitions. Each direction in FIG. 1 corresponds to the direction when the fuel cell stack 100 is assembled (see FIG. 4), which will be described later. This direction is not necessarily the same as the direction when the fuel cell stack 100 is mounted on a vehicle. For example, when the fuel cell stack 100 is mounted on a vehicle, the front-rear direction in FIG. 1 becomes the up-down direction (vertical direction), the up-down direction in FIG. 1 becomes the front-rear direction or the left-right direction, and the left-right direction in FIG. 1 becomes the front-rear direction or the left-right direction as it is.

[0011] As shown in FIG. 1, the fuel cell stack 100 has a cell stack 10, end units 20 arranged at both the upper and lower ends of the cell stack 10, and a case 30 surrounding the cell stack 10, and has an overall roughly rectangular parallelepiped shape.

[0012] The case 30 has four generally rectangular side walls 300 respectively facing the front, right, rear, and left sides of the cell stack 10. These four side walls 300 form a generally box-shaped storage space SP0 with an open top and bottom. The case 30 is made of a metal such as aluminum or iron. Between the cell stack 10 and each side wall 300 of the case 30, a rod- or plate-shaped guide member 50 (FIG. 2) extending in the vertical direction is interposed.

[0013] 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 is formed by stacking a plurality of power generating cells 1 (for convenience, only a single cell 1 is shown) in the vertical direction while being guided by a guide member 50.

[0014] The power generating cell 1 has an electrode assembly 2 having an assembly including an electrolyte membrane and electrodes, and separators 3 arranged above and below the electrode assembly 2 to sandwich the electrode assembly 2. The electrode assemblies 2 and the separators 3 are arranged alternately in the vertical direction.

[0015] Separator 3 has a pair of upper and lower metal thin plates with a corrugated cross section, and is integrally formed by joining the outer peripheries of the pair of thin plates. Separator 3 is made of a conductive material with excellent corrosion resistance, such as titanium, titanium alloy, stainless steel, etc. The pair of thin plates are formed into an uneven shape by press molding or the like so as to form cooling channels inside separator 3 through which a cooling medium (e.g., water) flows, and the power generation surface of power generation cell 1 is cooled by the flow of the cooling medium.

[0016] The separator 3 on the upper side of the electrode assembly 2 is, for example, an anode side separator (anode separator), and an anode flow path through which a fuel gas containing hydrogen flows is formed between the anode separator 3 and the electrode assembly 2. The separator 3 on the lower side of the electrode assembly 2 is, for example, a cathode side separator (cathode separator), and a cathode flow path through which an oxidant gas containing oxygen flows is formed between the cathode separator 3 and the electrode assembly 2.

[0017] The electrode assembly 2 has a membrane electrode assembly (MEA) and a resin frame that supports the periphery of the membrane electrode assembly. The membrane electrode assembly has an electrolyte membrane, an anode electrode provided on the upper surface of the electrolyte membrane, and a cathode electrode provided on the lower surface of the electrolyte membrane. The membrane electrode assembly is sometimes called a membrane electrode structure. The electrolyte membrane is, for example, a solid polymer electrolyte membrane. The anode electrode is an electrode catalyst layer formed on the upper surface of the electrolyte membrane and serves as a reaction field for the electrode reaction, and a gas diffusion layer that diffuses and supplies the fuel gas is provided on the upper surface of the electrode catalyst layer. The cathode electrode is an electrode catalyst layer formed on the lower surface of the electrolyte membrane and serves as a reaction field for the electrode reaction, and a gas diffusion layer that diffuses and supplies the oxidant gas is provided on the lower surface of the electrode catalyst layer.

[0018] At the anode electrode, the fuel gas (hydrogen) supplied via the anode flow path and gas diffusion layer is ionized by the action of a catalyst and passes through the electrolyte membrane to move 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, the oxidant gas (oxygen) supplied via the cathode flow path and gas diffusion layer reacts with the hydrogen ions guided from the anode electrode and the electrons that have moved from the anode electrode to produce water. The produced water provides an appropriate humidity to the electrolyte membrane, and excess water is discharged outside the electrode assembly 2.

[0019] The upper and lower end units 20 each have a terminal plate 21, an insulating plate 22, and an end plate 23. The upper end unit 20 is sometimes called a dry side end unit, and the lower end unit 20 is sometimes called a wet side end unit. The pair of upper and lower terminal plates 21, 21 are arranged on both the upper and lower sides of the cell stack 10, sandwiching it between them. The pair of upper and lower insulating plates 22, 22 are arranged on both the upper and lower sides of the terminal plate 21, 21. The pair of upper and lower end plates 23, 23 are arranged on both the upper and lower sides of the insulating plates 22, 22, sandwiching them between them.

[0020] The terminal plate 21 is a generally rectangular metal plate member, and has a terminal portion for extracting the electric power generated by the electrochemical reaction in the cell stack 10. The insulating plate 22 is a generally rectangular non-conductive resin or rubber plate member, and electrically insulates the terminal plate 21 from the end plates 23. The end plates 23 are metal or high-strength resin plate members, and both upper and lower ends of the case 30 are fastened to the upper and lower end plates 23 with bolts, respectively.

[0021] A plurality of through holes (communicating holes) 20a to 20f are formed in the lower end unit 20, vertically penetrating the end unit 20. Note that the through holes 20a to 20f each include a through hole that penetrates the terminal plate 21, a through hole that penetrates the insulating plate 22, and a through hole that penetrates the end plate 23, but for convenience, these are collectively shown as through holes 20a to 20f in FIG.

[0022] The through hole 20a is a communication hole for supplying fuel gas to the inside of the cell stack 10. The through hole 20b is a communication hole for discharging a cooling medium from the cell stack 10 to the outside. The through hole 20c is a communication hole for discharging an oxidizing gas from the cell stack 10 to the outside. The through hole 20d is a communication hole for supplying an oxidizing gas to the inside of the cell stack 10. The through hole 20e is a communication hole for supplying a cooling medium to the inside of the cell stack 10. The through hole 20f is a communication hole for discharging a fuel gas from the cell stack 10 to the outside.

[0023] At both left and right ends of the cell stack 10, a plurality of flow paths (manifolds) are formed extending in the vertical direction so as to communicate with the through holes 20a to 20d. The fuel gas supplied through the through hole 20a is guided to the anode flow path inside the cell stack 10, and the oxidant gas supplied through the through hole 20d is guided to the cathode flow path. This causes power generation in the power generation cell 1. The supplied fuel gas and oxidant gas are discharged from the cell stack 10 through the through holes 20f and 20c, respectively. The cooling medium supplied through the through hole 20e is guided to the cell stack 10, thereby cooling the power generation surface. The cooling medium that has passed through the cell stack 10 is discharged through the through hole 20b.

[0024] Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Fig. 2, a guide support portion 35 for supporting a guide member 50 is provided on each of the inner surfaces 30a of the four side walls 300 facing the storage space SP0. The guide support portion 35 protrudes from the inner surface 30a of the side wall 300 toward the inside of the case (toward the center of the storage space SP0) and extends in the longitudinal direction (up and down direction) of the side wall 300. The guide support portion 35 has, for example, a recess 35a in a portion facing the storage space SP0. The guide member 50 fits into the recess 35a.

[0025] The guide member 50 is an elongated resin member extending in the vertical direction, and its cross-sectional shape is uniform along the longitudinal direction (vertical direction). The guide member 50 has recesses 51, for example, facing the inside of the case. The front, rear, left and right edges of the cell stack 10 are fitted into the recesses 51.

[0026] Specifically, protrusions 11 corresponding to the guide members 50 are provided on the front, rear, left and right edges of the separators 3 constituting the cell stack 10, and the separators 3 are stacked while the protrusions 11 fit into the recesses 51. In this case, by previously joining a single electrode assembly 2 to a single separator 3 by welding, adhesive or the like to form a set of unit cells or power generating cells 1, the electrode assemblies 2 can be stacked at the same time as the separators 3 are stacked. In addition, by stacking the separators 3 via the guide members 50, the cell stack 10 can be constructed while the separators 3 are accurately positioned relative to the case 30.

[0027] 3 is a cross-sectional view taken along line III-III in FIG. 1, showing the configuration of the through hole 20a of the end unit 20. The configurations of the other through holes 20b to 20f of the end unit 20 are the same as those in FIG. 3. As shown in FIG. 3, the through holes 20a include a through hole 210 of the terminal plate 21, a through hole 220 of the insulating plate 22, and a through hole 230 of the end plate 23. The terminal plate 21 and the insulating plate 22 form an intermediate plate. The intermediate plate may be formed only by the insulating plate 22. The insulating plate 22 has a protruding portion 221 protruding downward in correspondence with the position of the through hole 20a, and the through hole 220 is provided in the protruding portion 221.

[0028] The diameter of through hole 230 of end plate 23 is equal to the diameter of the outer circumferential surface of protrusion 221, and the outer circumferential surface of protrusion 221 is fitted into through hole 230. In the fitted state, lower end surface 22a of protrusion 221 and lower end surface 23a of end plate 23 are positioned on the same horizontal plane. Note that lower end surface 23a may be positioned lower than lower end surface 22a.

[0029] The above fuel cell stack 100 is assembled using an assembly device. Fig. 4 is a diagram showing a schematic configuration of the assembly device 200. Fig. 4 also shows one process of assembling the fuel cell stack 100 using the assembly device 200. As shown in Fig. 4, the assembly device 200 has a plurality of legs 201 standing on a base, and a roughly plate-shaped table 202 that is fixed to the upper ends of the legs 201 and extends horizontally.

[0030] In the table 202, a plurality of (e.g., four) through holes 202a are opened, which penetrate the table 202 in the up-down direction, corresponding to a plurality of through holes (e.g., four through holes 20a, 20c, 20d, and 20f) in the end unit 20. Note that Fig. 4 also shows an end plate 23 (wet-side end plate 23) placed on the upper surface of the table 202 and a case 30 fixed to the end plate 23. A guide member 50 is attached to the inside of a side wall 300 of the case 30.

[0031] A thin and elongated rod 203 is inserted into through-hole 202a from below table 202. Rod 203 is supported by a driving device 205 attached to the bottom surface of table 202 so as to be movable in the vertical direction. Driving device 205 has an actuator such as a cylinder or a motor, and can raise and lower rod 203 by driving the actuator. The outer diameter of rod 203 is smaller than the diameter of through-hole 230 in end plate 23, and rod 203 can pass through through-hole 230.

[0032] At the maximum lowered position (position A) where rod 203 has been lowered to the maximum, the upper end surface of rod 203 is located at a position substantially flush with or lower than the upper surface of table 202. Note that the upper end surface of rod 203 may protrude from the upper surface of table 202 up to a predetermined amount (e.g., the plate thickness of end plate 23). At the maximum raised position (position B) where rod 203 has been raised to the maximum, the upper end surface of rod 203 protrudes above the upper end surface of end plate 23 by a predetermined amount.

[0033] The upper end of the rod 203 fits into the through hole 220 of the insulating plate 22 up to a predetermined position. This is called the predetermined fitted state. In the predetermined fitted state, the rod 203 can support the insulating plate 22 without sliding on the circumferential surface of the through hole 220. This allows the insulating plate 22 to be held in the cell stacking position away from the upper surface of the end plate 23, as shown in position B in FIG. 4. In this state, the electrode assemblies 2 and the separators 3 (shown as power generating cells 1) are stacked alternately as shown by arrow Z. Note that in FIG. 4, the through holes of the power generating cells 1, i.e., the communication holes (FIG. 3) that communicate with the through holes 20a of the end units 20, are shown by dotted lines.

[0034] 5A is an enlarged view of the tip of the rod 203 in FIG. 4, and FIG. 5B is a view taken along the arrow VB in FIG. 5A. As shown in FIG. 5A, a plurality of elastic bodies 204 (four in the figure) are attached to the outer peripheral surface of the upper end of the rod 203 at equal intervals in the circumferential direction. The elastic bodies 204 are made of resin or rubber. Although exaggerated in FIG. 5B, the diameter of a circumscribed circle 204a passing through the outer vertex of the elastic body 204 is slightly larger than the diameter of the through hole 220. Therefore, the elastic body 204 is compressed in the radial direction and fitted into the through hole 220. That is, the corner of the elastic body 204 that interferes with the through hole 220 is compressed, and the elastic body 204 is fitted.

[0035] The through hole 220 has a contact portion 220a on the periphery thereof against which the elastic body 204 contacts. The through hole 220 has a gradually smaller diameter, for example, from the lower end entrance toward the top. This forms the contact portion 220a. By providing such a contact portion 220a, the maximum amount of fitting of the elastic body 204 into the through hole 220 is limited. As a result, when the elastic body 204 is fully fitted, In A fixed fitted state is reached, and the maximum fitting position of rod 203 in the specified fitted state can be determined. Note that a claw mechanism consisting of a biasing member such as a leaf spring may be provided between elastic body 204 and the outer circumferential surface of rod 203, and a biasing force may be applied to elastic body 204 at the maximum fitting position by reducing the diameter of through hole 202a, thereby fixing the position of elastic body 204 on the circumferential surface of through hole 220 via the claw mechanism. The claw mechanism may be configured to perform an action such as protruding in the outer diameter direction when elastic body 204 is fitted to a predetermined position.

[0036] 6A is a diagram showing a modified example of FIG. 5A. In the example of FIG. 6A, a step portion 222 is provided as an abutment portion 220a on the peripheral surface of the through hole 220. The step portion 222 has an end face 222a extending in the horizontal direction, and the diameter of the through hole 220 below the end face 222a is larger than the diameter of the through hole 220 above the end face 222a. The diameter of the outer peripheral surface of the rod 203 is approximately equal to the diameter of the through hole 220 below the end face 222a. As a result, in a predetermined fitting state, the upper end face of the rod 203 abuts against the end face 222a of the step portion 222, and the maximum fitting position of the rod 203 can be determined.

[0037] Fig. 6B is a diagram showing another modified example of Fig. 5A. In the example of Fig. 6B, the upper end corner of the rod 203 is tapered, and the rod 203 has a tapered surface 203a. The diameter of the outer circumferential surface of the rod 203 below the tapered surface 203a is larger than the diameter of the through hole 220 of the insulating plate 22, while the diameter of the upper end surface 203b of the rod 203 is smaller than the diameter of the through hole 220. As a result, the tapered surface 203a of the rod 203 abuts against the corner (abutment portion 220a) of the inner circumferential surface of the protruding portion 221 of the insulating plate 22, and the maximum fitting position of the rod 203 in a predetermined fitting state can be determined.

[0038] A method for assembling the fuel cell stack 100 according to this embodiment will be described. When assembling the fuel cell stack 100, first, as shown in Fig. 4, the wet-side end plate 23 (lower end plate) is mounted and fixed at a predetermined position on the upper surface of the table 202, and the lower end of the case 30 is fixed to the end plate 23 using bolts (mounting step). When the mounting step is completed, the rod 203 of the assembly device 200 is positioned below the through-hole 230 of the end plate 23.

[0039] Although not shown in the drawings, the mounting process further includes fitting the protrusion 221 of the insulating plate 22 into the through hole 230, mounting the insulating plate 22 on the upper surface of the end plate 23, and then mounting the terminal plate 21 on the upper surface of the insulating plate 22. Furthermore, the guide member 50 is inserted from the opening at the upper end of the case 30, and attached to the guide support portion 35 (FIG. 2) on the inner surface of the side wall 300.

[0040] Next, the driving device 205 (actuator) of the assembly device 200 is driven to move the rod 203 upward. As a result, the upper end of the rod 203 fits into the through hole 220 of the insulating plate 22, resulting in a predetermined fitted state. When the rod 203 moves upward in the predetermined fitted state, the insulating plate 22 is lifted away from the end plate 23 and held at a predetermined position (position B) where the rod 203 has risen to its maximum (holding step). Note that instead of lifting the insulating plate 22 by the upward movement of the rod 203, the insulating plate 22 may be mounted from above through an opening at the upper end of the case 30 after the rod 203 has risen to the maximum raised position (position B).

[0041] Next, the electrode assemblies 2 and separators 3 are alternately stacked on the upper surface of the terminal plate 21 through the opening at the top end of the case 30 to form the cell stack 10 (stacking process). At this time, the separators 3 are stacked together with the electrode assemblies 2 while the protrusions 11 (engagement portions) at the ends of the separators 3 engage with the guide members 50. This defines the position of the power generating cells 1 within the case, allowing the cell stack 10 to be formed with precision.

[0042] The stacking process is performed using a robot. That is, the separator 3 is sucked by the hand of the robot, the separator 3 is transported to a predetermined position, and then the sucking is stopped to stack the separator 3 at the predetermined position. In this case, the insulating plate 22 is lifted by the rod 203 and moved away from the end plate 23 to a predetermined position (position B) above, thereby shortening the distance from the hand of the robot to the insulating plate 22. This makes it possible to shorten the free fall distance when stacking the electrode assemblies 2 and the separators 3, or the combination of them into a unit. This makes it possible to suppress the electrode assemblies 2 and the separators 3 from sliding against the case 30 and the guide member 50 in the stacking process and becoming misaligned.

[0043] In the stacking step, each time a set of power generating cells 1 (unit cells) is stacked, the rod 203 is driven by the drive device 205 to descend by the thickness of the power generating cells 1 (lowering step). The stacking step and the lowering step are performed alternately. This allows the multiple power generating cells 1 to be easily stacked inside the case while being positioned along the case 30, without interference between the case 30 and the robot. When a predetermined number of power generating cells 1 are stacked, the rod 203 is lowered to a predetermined position (position A) where the insulating plate 22 is placed on the upper surface of the end plate 23, thereby completing the lowering step. The rod 203 may be moved downward after stacking of all the power generating cells 1 is completed.

[0044] Next, the dry-side end unit 20, i.e., the terminal plate 21, the insulating plate 22, and the end plate 23, are sequentially mounted on the upper surface of the cell stack 10. In this state, the dry-side end plate 23 is located above the upper end surface of the case 30. Next, a pressurizing machine is used to apply pressure from above the end plate 23, and the end plate 23 is pressed downward until it abuts against the upper end surface of the case 30. Then, the end plate 23 is fastened to the upper end surface of the case 30 using bolts (pressurizing step). This completes the assembly of the fuel cell stack 100. After the assembly is completed, the end plate 23 is released from the table 202, and the fuel cell stack 100 is transported to a predetermined position.

[0045] According to this embodiment, the following advantageous effects can be obtained. (1) A fuel cell stack 100 includes a cell stack 10 formed by alternately stacking electrode assemblies 2, each including an electrolyte membrane and an electrode, and separators 3, a case 30 surrounding the cell stack 10, and an end unit 20 disposed at an end of the cell stack 10 in the stacking direction (FIG. 1). The end unit 20 includes an end plate 23 fixed to an end of the case 30, and an insulating plate 22 disposed between the end plate 23 and the cell stack 10 (FIG. 1). The end plate 23 and the insulating plate 22 are provided with a plurality of through holes (communicating holes) 20a to 20f that pass through the end plate 23 and the insulating plate 22 in parallel with the stacking direction and are used to supply reactant gas and cooling medium to the cell stack 10 and discharge them from the cell stack 10 (FIG. 1). A through hole 220 in the insulating plate 22 is smaller than a through hole 230 in the end plate 23 (FIG. 3). The insulating plate 22 has an abutment portion 220a against which the tip of the rod 203 abuts against the peripheral surface of the through hole 220 so that the insulating plate 22 is supported so as to be movable up and down by the rod 203 passing through the through hole 230 of the end plate 23 mounted on the table 202 when assembling the fuel cell stack 100 (Figures 5A, 6A, and 6B).

[0046] With this configuration, the insulating plate 22 can be raised and lowered by vertical movement of the rod 203 while the end plate 23 is placed on the table. Therefore, the position at which the power generating cells 1 are stacked can be shifted upward, and the fuel cell stack 100 can be easily assembled even when the case 30 is fixed to the end plate 23. Therefore, the fuel cell stack 100 can be constructed at low cost.

[0047] When the insulating plate 22 is raised and lowered via the rod 203, as shown in FIG. 7 as a reference example, a through hole 231 for the rod 203 to pass through is drilled in the end plate 23 in addition to the through hole 230, and the bottom surface of the insulating plate 22 is supported by the upper end of the rod 203 that passes through the through hole 231. However, in this case, a new process of sealing the through hole 231 is required after the assembly of the fuel cell stack 100 is completed, which increases the number of parts and increases costs. In this respect, in the present embodiment, the rod 203 passes through the multiple through holes 230 previously provided in the end plate 23, i.e., the through holes 20a, 20c, 20d, and 20e for supplying and discharging the reactant gas (fuel gas, oxidant gas), and abuts against the abutment portion 220a provided on the peripheral surface of the multiple through holes 220 of the insulating plate 22. This eliminates the need to process a new through hole 231 for the rod to pass through in the end plate 23, thereby reducing costs. Furthermore, a seal portion is provided on the lower end surface of the insulating plate 22, but the abutment portion 220a is provided on the peripheral surface of the through hole 220 different from the seal portion, so that the fuel cell stack 100 can be assembled without damaging the seal portion.

[0048] (2) The contact portion 220a is formed by a step portion 222 (step portion) provided on the peripheral surface of the through hole 220 of the insulating plate 22 (FIG. 6A). This allows the upper end portion of the rod 203 to stably support the insulating plate 22.

[0049] (3) The insulating plate 22 protrudes toward the end plate 23, fits into the through hole 230 of the end plate 23, and has a protruding portion 221 in which the through hole 220 is provided (FIG. 3). This allows the position of the insulating plate 22 relative to the end plate 23 to be determined. In addition, the through hole 220 is elongated in the vertical direction, making it easy to provide the abutment portion 220a.

[0050] (4) The fuel cell stack 100 further includes a guide member 50 that is attached to the inner surface of the case 30 and extends in the stacking direction (FIG. 2). The separator 3 has a protrusion 11 that serves as an engagement portion that engages with the guide member 50 (FIG. 2). This allows the separators 3 to be stacked while being positioned by the guide member 50, and the position of each power generation cell 1 can be precisely defined. After assembly of the fuel cell stack 100 is complete, the cell stack 10 can be well supported by the guide member 50.

[0051] (5) A method of assembling a fuel cell stack 100 in which the stacking direction is vertical includes a mounting step of mounting the wet-side end plate 23 on the upper surface of a table 202 and fixing the lower end of the case 30 to the wet-side end plate 23; a holding step of holding the insulating plate 22 arranged above the wet-side end plate 23 at a cell stacking position above the wet-side end plate 23 via a rod 203 that is vertically movable relative to the table 202; a stacking step of alternately stacking electrode assemblies 2 including an electrolyte membrane and an electrode and separators 3 on the insulating plate 22 held via the rod 203 to form a cell stack 10; a lowering step of moving the rod 203 downward to lower the insulating plate 22 and place it on the upper surface of the wet-side end plate 23; and a pressurizing step of pressing the cell stack 10 from above via the dry-side end plate 23 to fix the dry-side end plate 23 to the upper end of the case 30 (FIG. 4). The wet-side end plate 23 and the insulating plate 22 are provided with a plurality of through holes 20a-20f (220, 230) that vertically penetrate the wet-side end plate 23 and the insulating plate 22, respectively, for supplying reactant gas and cooling medium to and discharging them from the cell stack 10 (FIG. 1). The through hole 220 of the insulating plate 22 is smaller than the through hole 230 of the wet-side end plate 23 (FIG. 3). In the holding step, the upper end of the rod 203 that has passed through the through hole 230 of the wet-side end plate 23 is brought into contact with the peripheral surface of the through hole 220 of the insulating plate 22, thereby holding the insulating plate 22 at the cell stacking position (FIG. 4). As a result, after the case 30 is fixed to the end plate 23, the electrode assemblies 2 and the separators 3 are stacked alternately, so that the electrode assemblies 2 and the separators 3 can be stacked while being positioned by the case 30 (more specifically, the guide member 50 attached to the case 30), thereby enabling the cell stack 10 to be constructed with high precision.

[0052] The above embodiment can be modified in various ways. Some modified examples will be described below. In the above embodiment, the rod 203 of the assembly device 200 is configured to be vertically movable, but the rod member may be provided extendable and retractable, so that it extends when the insulating plate 22 is raised and retracts when the insulating plate 22 is lowered. In the above embodiment, the contact portion 220a against which the upper end of the rod 203 abuts is provided on the insulating plate 22, but it may be provided on the terminal plate 21, and the intermediate plate on which the contact portion is provided is not necessarily the insulating plate 22. The configuration of the contact portion 220a against which the upper end of the rod 203 abuts is not limited to the above. For example, a throttling portion may be provided in the through hole (communicating hole) of the intermediate plate, and the upper end of the rod member may abut on the throttling portion. In this case, the throttling portion becomes the abutting portion.

[0053] In the above embodiment, the method of assembling the fuel cell stack 100 has been described, but the fuel cell stack 100 can be disassembled by following the procedure reverse to that of assembly, and the contact portion of the intermediate plate can be used in the same manner when disassembling. In the above embodiment, the guide member 50 that engages with the protrusion 11 provided at the end of the cell stack 10 is attached to the inner surface of the case 30 as a housing, but the configuration of the guide member and the engagement portion is not limited to the above. In the above embodiment, the table 202 is provided with the through hole 202a through which the rod 203 passes, but the assembly table may have any configuration as long as the rod member is held so as to be movable in the vertical direction. In the above embodiment, a single electrode assembly 2 and a single separator 3 are joined to form a set of unit cells, and each time a set of unit cells is stacked in the stacking process, the intermediate plate is lowered by the thickness of the set of unit cells via the rod 203 in the lowering process, but each time a plurality of sets of unit cells are stacked, the intermediate plate may be lowered by the thickness of the plurality of sets of unit cells. Instead of a unit laminate being formed by joining a single electrode assembly 2 and a single separator 3, a single electrode assembly 2 or a single separator 3 may be a unit laminate.

[0054] Although an example has been described above in which a fuel cell having the fuel cell stack 100 is mounted on a vehicle, the fuel cell stack can also be mounted on moving bodies other than vehicles, such as aircraft and ships, robots, and various industrial machines.

[0055] The above description is merely an example, and the present invention is not limited to the above-mentioned embodiment and modifications, as long as the features of the present invention are not impaired. The above-mentioned embodiment and one or more modifications can be arbitrarily combined, and modifications can be combined with each other.

[0056] 3 separator, 10 cell stack, 11 protrusion, 20a to 20f through hole, 22 insulating plate, 23 end plate, 30 case, 50 guide member, 100 fuel cell stack, 220 through hole, 220a contact portion, 222 step portion, 230 through hole

Claims

1. a cell stack formed by alternately stacking a membrane electrode assembly including an electrolyte membrane and an electrode and a separator; A housing that surrounds the cell stack; An end unit arranged at an end portion in a stacking direction of the cell stack; a guide member attached to an inner surface of the housing and extending in the stacking direction, the cell stack is formed by stacking unit stacks each of which is an assembly of the membrane electrode assembly and the separator that have been previously joined together, the separator has an engagement portion that engages with the guide member, The end unit has an end plate fixed to an end of the housing, and an intermediate plate disposed between the end plate and the cell stack, a plurality of communication holes are formed in the end plates and the intermediate plate, the communication holes penetrating the end plates and the intermediate plate in a direction parallel to the stacking direction, for supplying a reactant gas and a cooling medium to the cell stack and discharging the reactant gas and the cooling medium from the cell stack; the communication hole of the intermediate plate is smaller than the communication hole of the end plate, a fuel cell stack characterized in that the intermediate plate has an abutment portion against which a tip end of a rod member abuts against a peripheral surface of the communicating hole so that the intermediate plate is supported so as to be raised and lowered by a rod member passing through the communicating hole of the end plate mounted on an assembly table when the fuel cell stack is assembled or disassembled.

2. 2. The fuel cell stack according to claim 1, 2. A fuel cell stack according to claim 1, wherein the contact portion is formed by a step provided on a peripheral surface of the communication hole of the intermediate plate.

3. 3. The fuel cell stack according to claim 1, a fuel cell stack comprising: the intermediate plate having a protrusion that protrudes toward the end plate, the protrusion being fitted into the communication hole of the end plate and through which the communication hole is provided.

4. A method for assembling a fuel cell stack in which the stacking direction is a vertical direction, comprising: a mounting step of mounting a lower end plate on an upper surface of an assembly table and fixing a lower end portion of a case to the lower end plate; inserting a guide member through an opening at the top end of the case and attaching the guide member to an inner surface of the case; a holding step of holding an intermediate plate disposed above the lower end plate at a cell stacking position above the lower end plate via a rod member that is movable in a vertical direction with respect to the assembly table; a lamination step of alternately laminating a membrane electrode assembly including an electrolyte membrane and an electrode and a separator on the intermediate plate held via the rod member to form a cell stack; a lowering step of lowering the intermediate plate by moving the rod member downward and placing the intermediate plate on an upper surface of the lower end plate; a pressurizing step of pressing the cell stack from above via an upper end plate to fix the upper end plate to an upper end portion of the case, the lamination step includes: forming a unit laminate body by previously joining the membrane electrode assembly and the separator; and laminating the unit laminate bodies while engaging an engaging portion provided on the separator with the guide member to form the cell laminate; a plurality of communication holes are formed in the lower end plate and the intermediate plate, the communication holes penetrating the lower end plate and the intermediate plate in the up-down direction, respectively, for supplying a reactant gas and a cooling medium to the cell stack and discharging the reactant gas and the cooling medium from the cell stack; the communication hole of the intermediate plate is smaller than the communication hole of the lower end plate, a second end portion of the second plate that is connected to the second end portion of the second plate and that is connected to the second end portion of the second plate, the second end portion being connected to the second end portion of the second plate and that is connected to the second end portion of the second plate.

5. A method for assembling a fuel cell stack according to claim 4, The method for assembling a fuel cell stack is characterized in that the lowering step includes lowering the intermediate plate by an amount equivalent to a thickness of the unit laminate each time the unit laminate is stacked in the stacking step, and the stacking step and the lowering step are performed alternately.

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