Fuel cell

Abstract

To provide a fuel cell capable of stabilizing quality.SOLUTION: The fuel cell 11 includes a fuel cell stack 13 in which a plurality of plate-shaped fuel cells 12 each having a power generation part and a pair of separators sandwiching the power generation part are stacked, and a pair of end plates 14 sandwiching the fuel cell stack 13 from both sides in a stacking direction Z of the fuel cells 12. The pair of end plates 14 are fastened to each other by a plurality of fastening members 15 rotating about a first axis line J1 extending in the stacking direction Z. The first outer surface 22 of the first end plate 14a which is one of the pair of end plates 14 is provided with one gear 24 configured to be rotatable about a second axis line J2 extending in the stacking direction Z. The gear 24 is configured so that the rotational force when rotated is simultaneously transmitted to the plurality of fastening members 15 as a rotational force in a tightening direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fuel cell. [Background technology]

[0002] Conventionally, a known fuel cell is that shown in Patent Document 1, for example. This fuel cell has a structure in which a fuel cell stack, which is made up of multiple stacked fuel cells, is sandwiched between a pair of end plates on both sides in the stacking direction. The pair of end plates is fastened with a number of bolts to apply a compressive force to the fuel cell stack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-20886 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the fuel cell described above, since the multiple bolts are tightened in sequence, the compressive force applied to the fuel cell stack is uneven, which causes uneven surface pressure to be applied to each fuel cell that makes up the fuel cell stack, resulting in the problem of unstable quality of the fuel cell. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. The fuel cell that solves the above problem is a fuel cell comprising a fuel cell stack formed by stacking multiple plate-shaped fuel cell cells, each having a power generation unit and a pair of separators sandwiching the power generation unit, and a pair of end plates sandwiching the fuel cell stack on both sides in the stacking direction of the fuel cell cells, wherein the pair of end plates are fastened to each other by multiple fastening members that rotate around a first axis extending in the stacking direction, and a rotating body configured to be rotatable around a second axis extending in the stacking direction is provided on the outer surface of either of the pair of end plates in the stacking direction, and the rotating body is configured so that when rotated, the rotational force is simultaneously transmitted to the multiple fastening members as rotational force in a tightening direction.

[0006] With this configuration, multiple fastening members can be fastened simultaneously by simply rotating a single rotor, allowing the pair of end plates to compress the fuel cell stack uniformly in the stacking direction, thereby applying uniform surface pressure to each fuel cell that makes up the fuel cell stack and stabilizing the quality of the fuel cell. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view of a fuel cell according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of the fuel cell of FIG. [Figure 3] FIG. 2 is an exploded perspective view of a fuel cell. [Figure 4] FIG. 10 is a cross-sectional view of a fuel cell according to a modified example. [Figure 5] FIG. 5 is a plan view of the fuel cell of FIG. [Figure 6] FIG. 10 is a plan view of another modified example of a fuel cell. [Figure 7] FIG. 10 is a plan view of a fuel cell according to yet another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment will be described below with reference to the drawings. <Fuel cell 11> As shown in Figure 1, the fuel cell 11 includes a fuel cell stack 13 in which a plurality of rectangular plate-shaped fuel cell cells 12 that generate electricity are stacked in the thickness direction, and a pair of end plates 14 that sandwich the fuel cell stack 13 on both sides in the stacking direction Z of the fuel cell cells 12.

[0009] The pair of end plates 14 are, for example, square-shaped and made of metal. One of the pair of end plates 14 is designated as a first end plate 14a, and the other is designated as a second end plate 14b. The pair of end plates 14 are fastened together by a plurality (four in this example) of metal fastening members 15 that rotate about a first axis J1 extending in the stacking direction Z, thereby compressing the fuel cell stack 13 in the stacking direction Z.

[0010] Between each of the pair of end plates 14 and the fuel cell stack 13, there are interposed terminal plates (not shown) for collecting current and insulating plates (not shown) for providing insulation.

[0011] 1 and 2, each fastening member 15 has a bolt 16 whose axis is the first axis J1 and an annular nut 17 whose axis is also the first axis J1. The bolt 16 has a shank 18 and a hexagonal head 19 provided at one end of the shank 18. An annular gear portion 20 is formed integrally with the outer periphery of the nut 17. Circular insertion holes 21 are formed near the four corners of the pair of end plates 14, respectively, to pass through them. The centers of the four insertion holes 21 formed in each end plate 14 are arranged on the same circumference.

[0012] The shank 18 of the bolt 16 is inserted into each of the insertion holes 21 of the pair of end plates 14 so as to connect the pair of end plates 14. That is, the shank 18 of the bolt 16 is inserted into the insertion hole 21 of the first end plate 14a and the insertion hole 21 of the second end plate 14b that faces the insertion hole 21 in the stacking direction Z.

[0013] In this case, the tip of the shaft 18 of the bolt 16 protrudes outward in the stacking direction Z beyond a first outer surface 22, which is the outer surface of the first end plate 14a in the stacking direction Z, and the head 19 of the bolt 16 is fixed by welding or the like in contact with a second outer surface 23, which is the outer surface of the second end plate 14b in the stacking direction Z. Therefore, the bolt 16 does not rotate with respect to the insertion hole 21.

[0014] Nuts 17 are threaded onto the tips of the shafts 18 of the four bolts 16 that protrude from the first outer surface 22 of the first end plate 14a. By rotating the nuts 17 in the tightening direction, the pair of end plates 14 are fastened together by the four nuts 17 and the four bolts 16.

[0015] A gear 24 is provided in the center of the first outer surface 22 of the first end plate 14a as an example of a rotating body configured to be rotatable in both forward and reverse directions about a second axis J2 extending in the stacking direction Z. The second axis J2 passes through the center of the pair of end plates 14 and extends parallel to the first axis J1. The gear 24 has a larger outer diameter and a greater thickness than the nut 17.

[0016] One gear 24 meshes with the gear portions 20 of the four nuts 17. Therefore, when one gear 24 is rotated, it is in direct contact with the gear portions 20 of the four nuts 17 and simultaneously transmits a rotational force to them. In other words, when one gear 24 is rotated, the rotational force is simultaneously transmitted to the four nuts 17 as a rotational force in the tightening direction. A hexagonal protrusion 25, for example, is formed in the center of the gear 24 for engaging a general-purpose tool such as a socket wrench when rotating the gear 24.

[0017] <Fuel cell 12> 1 and 3, the fuel cell 12 has a rectangular plate shape and is stacked in multiple layers to form the fuel cell stack 13. The fuel cell 12 includes a rectangular plate-shaped power generation unit 26, a pair of gas diffusion layers 27 each having a rectangular sheet shape sandwiching the power generation unit 26, and a pair of rectangular plate-shaped separators 28. In other words, the fuel cell 12 has a structure in which the pair of gas diffusion layers 27, the power generation unit 26, and the pair of separators 28 are stacked.

[0018] In the following description, the long side direction, short side direction, and thickness direction of the fuel cell 12 are referred to as the long side direction X, short side direction Y, and stacking direction Z, respectively. The long side direction X, short side direction Y, and stacking direction Z are perpendicular to each other. The thickness direction of the fuel cell 12 is the same direction as the stacking direction Z.

[0019] 3, the power generation unit 26 includes a rectangular plate-shaped resin frame member 29 and a rectangular sheet-shaped power generation section 30 supported by the frame member 29. The power generation section 30 is formed, for example, by a membrane electrode assembly (MEA). The frame member 29 has a rectangular opening 31 in the center.

[0020] The frame member 29 supports the power generation section 30 housed in the opening 31. The power generation section 30 is sandwiched between a pair of gas diffusion layers 27 in the stacking direction Z. A pair of separators 28 sandwich the power generation unit 26 in the stacking direction Z from the outside of the pair of gas diffusion layers 27. One of the pair of separators 28 (on the cathode side) is a first separator 28a, and the other (on the anode side) is a second separator 28b.

[0021] <Flow path configuration of fuel cell 12> As shown in Figures 1 and 3, at both ends of the power generation section 30 of the fuel cell 12 sandwiched in the long side direction X, i.e., at both ends of the frame member 29 and the pair of separators 28 sandwiching the power generation section 30 in the long side direction X, three rectangular through holes are formed aligned in the short side direction Y.

[0022] The three through holes at one end of the fuel cell 12 in the long side direction X are a fuel gas supply hole 32, a coolant discharge hole 33, and an oxidant gas discharge hole 34. The three through holes at the other end of the fuel cell 12 in the long side direction X are an oxidant gas supply hole 35, a coolant supply hole 36, and a fuel gas discharge hole 37.

[0023] The fuel gas supply hole 32 constitutes an inlet-side fuel gas manifold to which fuel gas is supplied in the fuel cell stack 13. The fuel gas discharge hole 37 constitutes an outlet-side fuel gas manifold from which fuel gas is discharged in the fuel cell stack 13. The oxidant gas supply hole 35 constitutes an inlet-side oxidant gas manifold to which oxidant gas is supplied in the fuel cell stack 13. The oxidant gas discharge hole 34 constitutes an outlet-side oxidant gas manifold from which oxidant gas is discharged in the fuel cell stack 13. Each of the above manifolds extends in the stacking direction Z of the fuel cell cells 12 when the fuel cell stack 13 is constructed.

[0024] An oxidant gas flow path (not shown) is formed between the frame member 29 and the power generation section 30 on the one hand and the first separator 28a on the other hand, allowing the oxidant gas supplied from the oxidant gas supply hole 35 to pass through the power generation section 30 in the long side direction X and flow to the oxidant gas discharge hole 34 on the other hand. This oxidant gas flow path is made up of a plurality of grooves formed on the surface of the first separator 28a facing the power generation section 30 on the other hand.

[0025] A fuel gas flow path is formed between the frame member 29 and the power generation section 30 on the one hand and the second separator 28b on the other hand, which causes fuel gas supplied from the fuel gas inlet 32 ​​to pass through the power generation section 30 in the long side direction X and flow to the fuel gas outlet 37 on the other hand. This fuel gas flow path is made up of a plurality of grooves 38 formed on the surface of the second separator 28b facing the power generation section 30 on the other hand.

[0026] When a plurality of fuel cells 12 are stacked to form a fuel cell stack 13, a coolant flow path (not shown) is formed between the first separator 28a of one of two fuel cells 12 and the second separator 28b of the other of the two fuel cells 12 that are adjacent in the stacking direction Z. This coolant flow path allows the coolant supplied from the coolant supply hole 36 to flow to the coolant discharge hole 33.

[0027] <Power generation by fuel cell stack 13> 1 and 3, in each of the fuel cell cells 12 constituting the fuel cell stack 13, an oxidant gas containing oxygen is supplied to one surface (cathode side) in the stacking direction Z of the power generation section 30, and a fuel gas containing hydrogen is supplied to the other surface (anode side) in the stacking direction Z of the power generation section 30. As a result, the fuel cell cells 12 generate electricity based on an electrochemical reaction between the fuel gas and the oxidant gas in the power generation section 30. The fuel cell cells 12 generate heat when generating electricity, but are cooled by a cooling medium flowing through a cooling medium flow path (not shown).

[0028] <Operation of the embodiment> Next, the operation of assembling the fuel cell 11 will be described. 1 and 2, when assembling a fuel cell 11, first, a plurality of fuel cells 12 are stacked to form a fuel cell stack 13. Next, the fuel cell stack 13 is sandwiched between a first end plate 14a and a second end plate 14b on both sides in the stacking direction Z of the fuel cells 12. In this case, a gear 24 configured to be rotatable in both forward and reverse directions about a second axis J2 is provided in the center of the first outer surface 22 of the first end plate 14a.

[0029] Next, the four bolts 16 that have been inserted into the four insertion holes 21 of the second end plate 14b are inserted into the four insertion holes 21 of the first end plate 14a. As a result, the tips of the shanks 18 of the four bolts 16 protrude outward in the stacking direction Z beyond the first outer surface 22 of the first end plate 14a. Meanwhile, the heads 19 of the four bolts 16 are in contact with the second outer surface 23 of the second end plate 14b.

[0030] Next, the heads 19 of the four bolts 16 are fixed to the second outer surface 23 of the second end plate 14b by, for example, welding. This prevents the four bolts 16 from rotating relative to the insertion holes 21. Next, four nuts 17 are screwed onto the tips of the shafts 18 of the four bolts 16 that protrude outward in the stacking direction Z beyond the first outer surface 22 of the first end plate 14a. At this time, the gear portions 20 of the four nuts 17 are each directly engaged with one gear 24.

[0031] Next, when a general-purpose tool such as a socket wrench is engaged with the protrusion 25 of the gear 24 and the gear 24 is rotated counterclockwise in Fig. 2, the rotational force of the gear 24 is simultaneously transmitted to the four nuts 17. In other words, the rotational force of the gear 24 is simultaneously transmitted to the four nuts 17 as a rotational force in the clockwise direction in Fig. 2, which is the direction in which the nuts 17 are tightened.

[0032] Then, the four nuts 17 are tightened simultaneously with the same predetermined rotational force, and the fuel cell stack 13 is uniformly compressed in the stacking direction Z by the first end plate 14a and the second end plate 14b. This completes the assembly of the fuel cell 11. In the fuel cell 11 assembled in this manner, uniform surface pressure is applied to each of the fuel cell units 12 that make up the fuel cell stack 13. This stabilizes the quality of the fuel cell 11.

[0033] Incidentally, if there is a bias in the surface pressure applied to each fuel cell 12 constituting the fuel cell stack 13 in the fuel cell 11, the power generation performance of the fuel cell 11 will decrease, and the quality of the fuel cell 11 will become unstable.

[0034] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) The fuel cell 11 includes a fuel cell stack 13 formed by stacking a plurality of plate-shaped fuel cell units 12, each having a power generation unit 30 and a pair of separators 28 sandwiching the power generation unit 30 therebetween, and a pair of end plates 14 that sandwich the fuel cell stack 13 from both sides in the stacking direction Z. The pair of end plates 14 rotate about a first axis J1 extending in the stacking direction Z and are fastened to each other by a plurality of fastening members 15, each having an annular gear portion 20. A gear 24 configured to be rotatable about a second axis J2 extending in the stacking direction Z is provided on a first outer surface 22 of a first end plate 14a, which is one of the pair of end plates 14. The gear 24 is engaged with the gear portions 20 of the plurality of fastening members 15, and is configured so that when the gear 24 is rotated, rotational force is simultaneously transmitted to the plurality of fastening members 15 as rotational force in a tightening direction.

[0035] According to the above configuration, by rotating one gear 24 through meshing between one gear 24 and each gear portion 20, it is possible to more reliably transmit rotational force from one gear 24 to multiple fastening members 15 (nuts 17). Therefore, by simply rotating one gear 24, multiple fastening members 15 can be tightened simultaneously, and the fuel cell stack 13 can be uniformly compressed in the stacking direction Z by the pair of end plates 14. Therefore, uniform surface pressure is applied to each fuel cell 12 constituting the fuel cell stack 13, making it possible to stabilize the quality of the fuel cell 11.

[0036] (2) In the fuel cell 11, the gear 24 transmits a rotational force to the gear portions 20 of the multiple fastening members 15 while being in direct contact with them. According to the above configuration, by rotating the gear 24, the rotational force of the gear 24 can be directly transmitted to the plurality of fastening members 15 (nuts 17). Therefore, the rotational force of the gear 24 can be efficiently transmitted to the plurality of fastening members 15.

[0037] (3) In the fuel cell 11, the gear 24 has a central portion formed with a hexagonal projection 25 for engaging with a general-purpose tool when rotating the gear 24. According to the above configuration, the gear 24 can be rotated using only a general-purpose tool, without the need for a dedicated tool.

[0038] <Example of change> The above embodiment can be modified as follows: Furthermore, the above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0039] As shown in FIGS. 4 and 5 , in the fuel cell 11, the positions of the heads 19 of the bolts 16 and the nuts 17 may be interchanged. That is, an annular gear portion 20 is integrally formed on the outer edge of the heads 19 of the bolts 16. The gear portion 20 of the heads 19 of the bolts 16 meshes with a gear 24. The heads 19 of the bolts 16 contact the first outer surface 22 of the first end plate 14a. The tip ends of the shafts 18 of the bolts 16 protrude outward in the stacking direction Z beyond the second outer surface 23 of the second end plate 14b. The nuts 17 are fixed to the second outer surface 23 of the second end plate 14b by welding or the like while threadedly engaging with the tip ends of the shafts 18 of the bolts 16. Therefore, the nuts 17 are prevented from rotating. Even with this configuration, the same effects as those of the first embodiment can be obtained.

[0040] 6, in the fuel cell 11, the gear portions 20 of the four nuts 17 may be configured to mesh with one gear 24 via one transmission gear 39. In this case, the outer diameters of the gear portions 20 of the nuts 17, the transmission gear 39, and the gear 24 may be changed as appropriate.

[0041] In the fuel cell 11 shown in FIG. 6, the gear portions 20 of the four nuts 17 may be configured to mesh with one gear 24 via a plurality of transmission gears 39, respectively. 7, in the fuel cell 11, instead of the gear 24, a disk-shaped rotating member 41 having an annular friction member 40 made of rubber or the like with high friction resistance attached to its outer periphery may be used as an example of a rotating body, and the gear portion 20 on the outer periphery of the nut 17 may be replaced with the annular friction member 40. In this case, the friction member 40 of each nut 17 and the friction member 40 of the rotating member 41 are in contact with each other. Even in this case, the rotational force of the rotating member 41 can be transmitted to each nut 17 by the frictional force between the friction member 40 of each nut 17 and the friction member 40 of the rotating member 41, thereby achieving the same effects as those of the first embodiment.

[0042] Instead of the protrusion 25, a handle for manually rotating the gear 24 may be provided at the center of the gear 24. In this way, the gear 24 can be easily rotated manually without the need for tools.

[0043] A hexagonal recess may be provided in the center of the gear 24 instead of the protrusion 25. In this way, the gear 24 can be rotated using a hexagonal wrench. In the fuel cell 11, the pair of end plates 14 may be fastened together by two fastening members 15, three fastening members 15, or five or more fastening members 15.

[0044] The end plate 14 is not limited to a square shape, but may be a polygonal shape such as a triangular shape or a hexagonal shape, or may be a circular shape or an elliptical shape. [Explanation of symbols]

[0045] 11...fuel cell 12...Fuel cell 13...Fuel cell stack 14...End plate 14a...First end plate 14b...Second end plate 15...Fastening member 16...Volts 17...Nat 18...Shaft 19...Head 20...Gear section 21...Through hole 22...First outer surface 23…Second outer surface 24...Gear as an example of a rotating body 25...Convex part 26...Power generation unit 27...Gas diffusion layer 28...Separator 28a...First separator 28b...Second separator 29...Frame member 30...Power generation section 31...Opening 32...Fuel gas supply hole 33…Cooling medium discharge hole 34...Oxidant gas exhaust hole 35...Oxidant gas supply hole 36…Cooling medium supply hole 37...Fuel gas exhaust hole 38...Groove 39...Transmission gear 40...Friction member 41... Rotating member as an example of a rotating body J1…1st axis J2…Second axis X: Long side direction Y: Short side direction Z…Stacking direction

Claims

1. A fuel cell comprising: a fuel cell stack in which a plurality of plate-shaped fuel cell units are stacked, each of which has a power generation unit and a pair of separators sandwiching the power generation unit; and a pair of end plates sandwiching the fuel cell stack from both sides in the stacking direction of the fuel cell units, the pair of end plates are fastened to each other by a plurality of fastening members that rotate around a first axis extending in the stacking direction, a rotating body configured to be rotatable about a second axis extending in the stacking direction is provided on an outer surface of one of the pair of end plates in the stacking direction, The fuel cell is characterized in that the rotating body is configured so that when rotated, the rotational force is simultaneously transmitted to the plurality of fastening members as rotational forces in the tightening direction.

2. 2. The fuel cell according to claim 1, wherein the rotating body transmits the rotational force in a state of direct contact with the plurality of fastening members.

3. the rotating body is constituted by one gear, 3. The fuel cell according to claim 1, wherein each of the plurality of fastening members has an annular gear portion that meshes with the gear.

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