Fuel cell, electrochemical device, and fuel cell fastening adjustment method

Abstract

To provide a fuel cell which can apply a uniform surface pressure from a tightening plate to a cell stacked body, even when the tightening plate is deflected.SOLUTION: According to an embodiment, a fuel cell includes: a cell staked body 10 including a plurality of fuel cells stacked one on another; a collecting plate 20 located on the cell stacked body 10 in a stacking direction; an insulating plate 30 located on the collecting plate 20; and a tightening structure 40 located on the insulating plate 30 and configured to hold the collecting plate 20 and the insulating plate 30 on the cell stacked body 10 by being tightened toward the cell stacked body 10. The tightening structure 40 includes a first tightening plate 41 including a planar portion in surface contact with the insulating plate 30, and a second tightening plate 42 located on the first tightening plate 41 and configured to press the first tightening plate 41 against the insulating plate 30 by being tightened toward the cell stacked body 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE PRESENTLY PREFERRED EMBODIMENTS The present invention relates to a fuel cell, an electrochemical device, and a method for tightening and adjusting a fuel cell. [Background technology]

[0002] Electrochemical devices such as fuel cells, electrolysis devices, etc. are known. A fuel cell is a device that extracts electrical energy from a fuel, such as hydrogen, by chemically reacting with an oxidant, such as air.

[0003] One example of a fuel cell includes a cell stack in which a plurality of fuel cell units are stacked, a pair of current collecting plates, a pair of insulating plates, and a pair of fastening plates.

[0004] In the above type of fuel cell, a pair of current collector plates, a pair of insulating plates, and a pair of clamping plates are arranged to sandwich the cell stack. The current collector plate, insulating plate, and clamping plate on one side are arranged in this order on one end face in the stacking direction of the cell stack. The current collector plate, insulating plate, and clamping plate on the other side are arranged in this order on the other end face in the stacking direction of the cell stack. The pair of clamping plates are then clamped together by fastening material that straddles the pair of clamping plates so that they approach each other. This integrates the various components.

[0005] The above-mentioned clamping plate usually has a plurality of protruding portions that protrude toward the outer periphery of the cell stack. Each protruding portion is provided with a fastening position. When the pair of clamping plates are fastened to approach each other, the clamping plates receive a clamping force at each fastening position. At this time, the clamping plates tend to bend due to the fastening, and for example, their central portions tend to float.

[0006] In a fuel cell using a clamping plate, it is desirable to make the surface pressure from the clamping plate to the cell stack uniform so as to prevent the contact resistance between adjacent fuel cell cells from becoming large. However, the above-mentioned floating can hinder the uniformity of the surface pressure.

[0007] Known clamping plate structures include a structure having a plurality of beams that are combined so as to intersect with each other, and a structure in which the clamping plate is integrally molded using a die from the viewpoint of simplifying the parts.

[0008] In a fastening plate having a structure with multiple beams, the above-mentioned floating can be suppressed by increasing the plate thickness or providing multiple ribs to increase the rigidity, but this may increase the cost due to the complex shape and structure.

[0009] On the other hand, in the case of a clamping plate having an integrally molded structure, the plate thickness is usually restricted to about a few mm from the viewpoint of workability (processing limit) in pressing and bending. Therefore, it is difficult to ensure rigidity. Therefore, in the case of a clamping plate having an integrally molded structure, a convex part is provided on the cell stack side at a position that is likely to float when clamped, so that the surface pressure on the cell stack is made uniform.

[0010] However, in the clamping plate having the above-mentioned convex portion, the surface pressure against the insulating plate differs between, for example, the convex portion and its surroundings. In this case, distributed pressure may be applied from the clamping plate to the cell stack via the current collector plate and insulating plate, which generally have low rigidity. Therefore, even in the clamping plate having the convex portion, there is still room for improvement in terms of uniformity of the surface pressure. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 5740214 [Patent Document 2] JP 2019-46540 A Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, the problem that the present invention aims to solve is to provide a fuel cell, an electrochemical device, and a method for adjusting the clamping of a fuel cell, which can apply uniform surface pressure from the clamping plate to the cell stack even if the clamping plate is deflected. [Means for solving the problem]

[0013] A fuel cell according to one embodiment includes a cell stack in which a plurality of fuel cells are stacked, a current collector plate arranged on the cell stack in the stacking direction of the fuel cells, an insulating plate arranged on the current collector plate, and a clamping structure arranged on the insulating plate and fastened to the cell stack to hold the current collector plate and the insulating plate to the cell stack. The clamping structure includes a first clamping plate having a flat portion in surface contact with the insulating plate, and a second clamping plate arranged on the first clamping plate and fastened to the cell stack to press the first clamping plate against the insulating plate.

[0014] An electrochemical device according to one embodiment includes a cell stack in which a plurality of electrochemical cells are stacked, a current collector plate disposed on the cell stack in the stacking direction of the electrochemical cells, an insulating plate disposed on the current collector plate, and a clamping structure disposed on the insulating plate and clamped to the cell stack to hold the current collector plate and the insulating plate to the cell stack. The clamping structure includes a first clamping plate having a flat portion in surface contact with the insulating plate, and a second clamping plate disposed on the first clamping plate and clamped to the cell stack to press the first clamping plate against the insulating plate.

[0015] A method for adjusting the fastening of a fuel cell according to one embodiment is a method for adjusting the fastening of a fuel cell including a cell stack in which a plurality of fuel cell units are stacked, a current collector plate arranged on the cell stack in the stacking direction of the fuel cell units, an insulating plate arranged on the current collector plate, and a fastening plate arranged on the insulating plate and fastened to the cell stack to hold the current collector plate and the insulating plate to the cell stack. This method includes the steps of removing the fastening plate, providing an additional fastening plate on the insulating plate having a flat portion that comes into surface contact with the insulating plate, and placing the fastening plate on the additional fastening plate and fastening it to the cell stack to press the additional fastening plate against the insulating plate, thereby holding the current collector plate and the insulating plate to the cell stack. Effect of the Invention

[0016] According to the present invention, even if the clamping plate is deflected, the clamping plate can apply a uniform surface pressure to the cell stack. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view of a fuel cell according to an embodiment; [Diagram 2] FIG. 2 is an exploded perspective view of the fuel cell shown in FIG. [Diagram 3] 2 is a schematic diagram illustrating a flow path structure in a cell laminate of the fuel cell shown in FIG. [Figure 4] 2 is a diagram showing a first fastening plate of the fastening structure provided in the fuel cell shown in FIG. 1. FIG. [Diagram 5] 1. FIG. 4 is a diagram showing a second fastening plate of the fastening structure provided in the fuel cell shown in FIG. [Figure 6] 6 is a cross-sectional view of a second fastening plate shown in FIG. 5 before being fastened. [Figure 7] 6 is a cross-sectional view of the second fastening plate shown in FIG. 5 after fastening. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a fuel cell 1, which is an example of an electrochemical device according to an embodiment, will be described with reference to the accompanying drawings.

[0019] <Overall configuration of fuel cell> Fig. 1 is a perspective view of a fuel cell 1 according to one embodiment. Fig. 2 is an exploded perspective view of the fuel cell 1. The fuel cell 1 shown in Figs. 1 and 2 is a device in which an electrochemical reaction occurs in fuel cell units 10c (see Fig. 2) included in a cell stack 10, thereby generating electricity.

[0020] The fuel cell 1 includes a cell stack 10 , a pair of current collector plates 20 , a pair of insulating plates 30 , a pair of fastening structures 40 , a fastening member 50 , and a manifold unit 60 .

[0021] As shown in Fig. 2, the cell stack 10 is formed by stacking a plurality of fuel cell units 10c as electrochemical cells. The fuel cell units 10c generate electricity by, for example, an electrochemical reaction between a fuel gas containing hydrogen and air (oxidant) containing oxygen. Note that the symbol St in Figs. 1 and 2 indicates the direction in which the fuel cell units 10c are stacked (hereinafter, the stacking direction).

[0022] The fuel cell 10c has, for example, an assembly formed by sandwiching an electrolyte membrane between a fuel electrode and an oxidizer electrode, and a separator forming a flow path for supplying fuel and oxidizer to the assembly. The separator may be formed of, for example, a conductive porous plate having micropores. The separator may also be provided with a cooling water flow path. The outer shape of the illustrated cell stack 10 is a rectangular parallelepiped, but it may also be a cube, a hexahedron, or another three-dimensional shape.

[0023] The pair of current collector plates 20 is composed of a first current collector plate 20a and a second current collector plate 20b. The first current collector plate 20a is disposed on one end face (upper side in Figs. 1 and 2) in the stacking direction St of the cell stack 10. The second current collector plate 20b is disposed on the other end face (lower side in Figs. 1 and 2) in the stacking direction St of the cell stack 10.

[0024] The first current collector plate 20a and the second current collector plate 20b are rectangular plate-shaped conductors, and are members for sending, for example, electrical energy generated in the cell stack 10 to the outside. The first current collector plate 20a and the second current collector plate 20b are formed in a shape identical to or similar to the rectangular end face of the cell stack 10. The first current collector plate 20a and the second current collector plate 20b are generally made of a metal plate material, but may be any conductor. The first current collector plate 20a and the second current collector plate 20b may be made of, for example, a graphite plate material.

[0025] The pair of insulating plates 30 is composed of a first insulating plate 30a and a second insulating plate 30b. The first insulating plate 30a is disposed on the first current collector plate 20a in the stacking direction St. The second insulating plate 30b is disposed on the second current collector plate 20b in the stacking direction St. The first insulating plate 30a and the second insulating plate 30b are rectangular plate-shaped insulators, and are formed of, for example, a synthetic resin plate material. In detail, the first insulating plate 30a and the second insulating plate 30b are formed in a rectangular shape that is the same as or similar to the facing first current collector plate 20a or second current collector plate 20b.

[0026] The pair of clamping structures 40 is composed of a first clamping structure 40a and a second clamping structure 40b. The first clamping structure 40a is disposed on the first insulating plate 30a in the stacking direction St. The second clamping structure 40b is disposed on the second insulating plate 30b in the stacking direction St. The first clamping structure 40a and the second clamping structure 40b each have a first clamping plate 41 and a second clamping plate 42. Hereinafter, the first clamping plate 41 in the first clamping structure 40a is represented by the first clamping plate 41a, and the second clamping plate 42 in the first clamping structure 40a is represented by the second clamping plate 42a. The first clamping plate 41 in the second clamping structure 40b is represented by the first clamping plate 41b, and the second clamping plate 42 in the second clamping structure 40b is represented by the second clamping plate 42b.

[0027] The first clamping plates 41a, 41b are plate-shaped members and are disposed between the corresponding insulating plates 30a, 30b and the corresponding second clamping plates 42a, 42b. In this embodiment, the first clamping plates 41a, 41b have the same shape, and the second clamping plates 42a, 42b also have the same shape. In the following description, the same reference numerals are used to designate the same components of the first clamping plates 41a, 41b, and the same reference numerals are used to designate the same components of the second clamping plates 42a, 42b.

[0028] However, the first fastening plates 41a, 41b do not necessarily have to have the same shape as each other, and the second fastening plates 42a, 42b do not necessarily have to have the same shape as each other.

[0029] 1 and 2, the second fastening plates 42a and 42b each have a plurality of fastening portions 424A, 424B, 424C, and 424D that protrude toward the outer periphery of the first fastening plates 41a and 41b when viewed in the stacking direction St. In detail, the fastening portions 424A, 424B, 424C, and 424D also protrude toward the outer periphery of the cell stack 10, the current collector plate 20, the insulating plate 30, and the manifold unit 60. Note that "protruding toward the outer periphery" here means going beyond members such as the first fastening plates 41a and 41b to the outside in a direction perpendicular to the stacking direction St.

[0030] 2, the fastening parts 424A, 424B, 424C, 424D have through holes 424A1, 424B1, 424C1, 424D1 formed therein, penetrating in the stacking direction St. A plurality of fastening members 50 are provided corresponding to the plurality of fastening parts 424A, 424B, 424C, 424D. The fastening members 50 straddle between the fastening parts 424A, 424B, 424C, 424D of the second fastening plate 42a on the upper side in the figure and the fastening parts 424A, 424B, 424C, 424D of the second fastening plate 42b on the lower side in the figure, and fasten the second fastening plate 42a and the second fastening plate 42b so as to approach each other.

[0031] The fastening member 50 in this embodiment includes a stud bolt 52, a pair of washers 54, and a pair of nuts 56. One end of the stud bolt 52 is passed through the through holes 424A1, 424B1, 424C1, and 424D1 in the second fastening plate 42a, and the other end of the stud bolt 52 is passed through the through holes 424A1, 424B1, 424C1, and 424D1 in the second fastening plate 42b. The washers 54 and the nuts 56 are attached to the one end and the other end of the stud bolt 52, respectively.

[0032] In the above-described attached state of the fastening member 50, at least one of the nuts 56 on one end side of the stud bolt 52 and the nuts 56 on the other end side of the stud bolt 52 is fastened to the cell stack 10 side, whereby the second fastening plates 42a, 42b are fastened to the cell stack 10 side by forces applied in the stacking direction St from the fastening portions 424A, 424B, 424C, 424D. As a result, the current collecting plate 20 and the insulating plate 30 are held to the cell stack 10. The structures of the first fastening plates 41a, 41b and the second fastening plates 42a, 42b will be described in detail later.

[0033] 1, the manifold unit 60 is disposed around the cell stack 10. The manifold unit 60 has an oxidizer electrode inlet manifold 61, an oxidizer electrode outlet manifold 62, an anode inlet manifold 63, and an anode outlet manifold 64.

[0034] As described above, the fuel cell 10c has, for example, an assembly formed by sandwiching an electrolyte membrane between a fuel electrode and an oxidizer electrode, and a separator that forms a flow path for supplying fuel and oxidizer to the assembly. In this case, the separator usually has a fuel electrode flow path formed on one side and an oxidizer electrode flow path formed on the other side.

[0035] Fig. 3 is a schematic diagram illustrating the flow path structure in the cell stack 10. In Fig. 3, the manifolds 61-64, a separator 65 constituting the fuel cell 10c, and a fuel electrode flow path 66 formed in the separator 65 are shown.

[0036] The anode inlet manifold 63 and the anode outlet manifold 64 face each other via the cell stack 10. The anode inlet manifold 63 and the anode outlet manifold 64 are fluidly connected to the anode flow path 66. When generating electricity, a fuel (fuel gas) containing hydrogen flows through a piping part (not shown), enters the anode inlet manifold 63, passes through the anode flow path 66, and is discharged to the outside from the anode outlet manifold 64 through a piping part (not shown). The oxidant flows through a piping part (not shown), enters the oxidizer electrode inlet manifold 61, passes through an oxidizer electrode flow path (not shown) on the separator, and is discharged to the outside from the oxidizer electrode outlet manifold 62 through a piping part (not shown).

[0037] <Configuration of fastening structure> The first clamping plates 41a, 41b and the second clamping plates 42a, 42b in the clamping structure 40 will be described in detail below. In this embodiment, the first clamping plates 41a, 41b have the same shape, and the second clamping plates 42a, 42b also have the same shape. Therefore, for ease of explanation, the first clamping plate 41a and the second clamping plate 42a will be described below, and an explanation of the first clamping plate 41b and the second clamping plate 42b will be omitted.

[0038] (First clamping plate) As described above, the first fastening plate 41a is a plate-like member and is disposed between the corresponding first insulating plate 30a and the corresponding second fastening plate 42a. Fig. 4 is a diagram showing the first fastening plate 41a as viewed from the side where the cell stack 10 is located. As shown in Figs. 2 and 4, the first fastening plate 41a is a roughly rectangular plate and has a flat portion 411 that comes into surface contact with the first insulating plate 30a.

[0039] In this embodiment, the first clamping plate 41a is formed to a size that is included in the first insulating plate 30a when it is overlapped with the facing first insulating plate 30a. Therefore, in this embodiment, the entire main surface of the first clamping plate 41a on the first current collector plate 20a side becomes the flat portion 411. In this embodiment, since the first clamping plate 41a is included in the first insulating plate 30a, the first clamping plate 41a is smaller than the first insulating plate 30a. Even in this case, it is desirable that the flat portion 411 be in surface contact with a range of 90% or more including the center of the first insulating plate 30a. On the other hand, the flat portion 411 may be formed larger than the first insulating plate 30a and be in surface contact with the entire first insulating plate 30a.

[0040] The first fastening plate 41a is made of a material having a higher strength than the first insulating plate 30a, and specifically, the bending rigidity of the first fastening plate 41a is greater than the bending rigidity of the first insulating plate 30a. The first fastening plate 41a may be made of, for example, a metal plate material or a high-strength resin plate material, but the material is not particularly limited.

[0041] Also, notches 412A, 412B, 412C, and 412D are formed at the four corners of the first fastening plate 41a. The above-mentioned fastening portions 424A, 424B, 424C, and 424D of the second fastening plate 42a protrude from the four corners of the first fastening plate 41a toward the outer periphery when viewed in the stacking direction St. In contrast, the notches 412A, 412B, 412C, and 412D extend in the opposite direction to the protruding direction of the corresponding fastening portions 424A, 424B, 424C, and 424D. By providing such notches 412A, 412B, 412C, and 412D, the surface pressure when the fastening portions 424A, 424B, 424C, and 424D that bend when fastened contact the first fastening plate 41a is reduced. In this embodiment, when the first fastening plate 41a is overlapped with the facing first insulating plate 30a, the periphery of the first fastening plate 41a is in a state of fitting along the periphery of the first insulating plate 30a except for the notched portions.

[0042] In this embodiment, the notches 412A, 412B, 412C, and 412D are formed in an L-shape as shown in Fig. 4, but the shape is not particularly limited. The notches 412A, 412B, 412C, and 412D may be, for example, rectangular, chamfered, or arc-shaped with a recess toward the center. Also, the notches 412A, 412B, 412C, and 412D may not be formed.

[0043] (Second clamping plate) The second clamping plate 42a is disposed on the first clamping plate 41a, and is fastened to the cell stack 10 side via the above-mentioned fastening portions 424A, 424B, 424C, and 424D, thereby pressing the first clamping plate 41a against the first insulating plate 30a. Fig. 5 is a diagram showing the second clamping plate 42a as viewed from the side where the cell stack 10 is located.

[0044] As shown in Fig. 2 and Fig. 5, the second fastening plate 42a has a plate body portion 420 that is approximately rectangular in plan view, and the above-mentioned fastening portions 424A, 424B, 424C, 424D that protrude from the four corners of the plate body portion 420. The plate body portion 420 is a portion that is overlapped with the first fastening plate 41a when fastened. Fig. 6 is a cross-sectional view of the second fastening plate 42a before fastening, taken along line VI-VI in Fig. 2. Fig. 7 is a cross-sectional view corresponding to Fig. 6, and is a cross-sectional view of the second fastening plate 42a after fastening.

[0045] 6 and 7, the plate body 420 is not flat but has an uneven shape. As shown in Fig. 1 and Fig. 2, the plate body 420 has an outer pressing part 110 formed along the outer periphery, an inner pressing part 115 provided closer to the center than the outer pressing part 110, and a beam part 120 as a connecting part connecting the outer pressing part 110 and the inner pressing part 115, and the beam part 120 is raised relative to the outer pressing part 110 and the inner pressing part 115 to form an uneven shape.

[0046] The outer pressing portion 110 and the inner pressing portion 115 are portions that come into contact with the first fastening plate 41a when the second fastening plate 42a is fastened to the cell stack 10. That is, the outer pressing portion 110 and the inner pressing portion 115 press the first insulating plate 30a via the first fastening plate 41a.

[0047] On the other hand, the beam portion 120 is a portion that does not contact the first fastening plate 41a. As shown in Fig. 6 and Fig. 7, the cross-sectional shape of the beam portion 120 in the thickness direction is U-shaped. The U-shaped beam portion 120 forms a recess 120A on its inner surface. The recess 120A is recessed on the side opposite to the cell stack 10 side, so that the beam portion 120 does not contact the first fastening plate 41a even when the second fastening plate 42b is fastened to the cell stack 10 side.

[0048] To explain the outer pressing portion 110 and the inner pressing portion 115 in more detail, in this embodiment, when the second fastening plate 42a is separated from the cell stack 10 as shown in Figure 6, the inner pressing portion 115 protrudes more than the outer pressing portion 110 in the thickness direction (stacking direction St).

[0049] 6, the protrusion amount Δt of the inner pressing portion 115 is exaggerated, but the protrusion amount Δt may be 25% to 40%, particularly 30% to 35%, of the thickness of the second fastening plate 42b. More specifically, for example, when the second fastening plate 42b is 2 mm thick and made of high tensile steel, the protrusion amount Δt may be 0.6 mm to 0.7 mm.

[0050] 7, when the second fastening plate 42a is fastened to the cell stack 10, the inner pressing portion 115 and the outer pressing portion 110 are in contact with the first fastening plate 41a on the same plane. In the second fastening plate 42a, the fastening portions 424A, 424B, 424C, and 424D are located on the outer periphery of the outer pressing portion 110. The second fastening plate 42a is fastened to the cell stack 10 by the force applied in the stacking direction St from the fastening portions 424A, 424B, 424C, and 424D.

[0051] When fastened as described above, the inner pressing portion 115 located on the second fastening plate 42a closer to the center than the outer pressing portion 110 is likely to float on the opposite side to the cell stack 10. Here, in the state where the second fastening plate 42a is separated from the cell stack 10 as described above, if the inner pressing portion 115 protrudes from the outer pressing portion 110 in the thickness direction, when the second fastening plate 42a is fastened to the cell stack 10 side, the inner pressing portion 115 and the outer pressing portion 110 can be in contact with the first fastening plate 41a. This allows the pressing force from the second fastening plate 42a to be applied uniformly to the first fastening plate 41a, and partial stress concentration can be avoided. Note that the desired value of the protrusion amount Δt of the inner pressing portion 115 relative to the outer pressing portion 110 varies depending on the thickness and material of the second fastening plate 42b.

[0052] The outer pressing portion 110 is formed along the four sides of the roughly rectangular plate main body portion 420, and has a first side portion 110A, a second side portion 110B, a third side portion 110C, and a fourth side portion 110D, as shown in Fig. 2. The inner pressing portion 115 is positioned so as to be surrounded by the first side portion 110A, the second side portion 110B, the third side portion 110C, and the fourth side portion 110D. The inner pressing portion 115 includes the center of the plate main body portion 420, and has a similar shape to the plate main body portion 420.

[0053] As described above, the beam portion 120 has a U-shaped cross section in the thickness direction, and more specifically, the beam portion 120 has a first beam element 124A, a second beam element 124B, a third beam element 124C, and a fourth beam element 124D that are connected to form the four sides of a substantially rectangular shape on the inner periphery side of the outer pressing portion 110. The first beam element 124A, the second beam element 124B, the third beam element 124C, and the fourth beam element 124D each have a U-shaped cross section in the thickness direction perpendicular to the longitudinal direction. The first beam element 124A, the second beam element 124B, the third beam element 124C, and the fourth beam element 124D are arranged point-symmetrically with respect to the center position of the inner pressing portion 115.

[0054] In this embodiment, the beam portion 120 and the fastening portions 424A, 424B, 424C, and 424D are connected. In detail, at the joint portion between the first beam element 124A and the second beam element 124B, the first beam element 124A and the second beam element 124B, which have a U-shaped cross section, are joined to each other at their inner wall portions facing the inner pressing portion 115 side, while their outer wall portions are not joined to each other by extending along the diagonal line of the plate main body portion 420 toward the corner portion side of the plate main body portion 420. The outer wall portions of the first beam element 124A and the outer wall portions of the second beam element 124B, which extend along the diagonal line of the plate main body portion 420, are connected to each other at their upper ends to form a U-shaped cross section. The fastening portion 424A is connected to the end portions of the outer wall portions of the first beam element 124A and the second beam element 124B that face the extension direction of the diagonal of the plate main body portion 420. The fastening portion 424A has a U-shaped cross-sectional shape, and is connected so as to make the U-shaped cross section continuous with the U-shaped cross section formed by the outer wall portion of the first beam element 124A and the outer wall portion of the second beam element 124B.

[0055] As in the above-mentioned connection mode, the fastening portion 424B is connected to the joint between the second beam element 124B and the third beam element 124C. The fastening portion 424C is connected to the joint between the third beam element 124C and the fourth beam element 124D. The fastening portion 424D is connected to the joint between the fourth beam element 124D and the first beam element 124A.

[0056] As described above, the beam portion 120 and the fastening portions 424A, 424B, 424C, and 424D are connected to each other, so that the beam elements are smoothly connected between the adjacent fastening portions. Here, the height of the center side of each of the beam elements 124A, 124B, 124C, and 124D may be smaller than the height of the portion on the fastening portions 424A, 424B, 424C, and 424D side located on both sides. In this embodiment, specifically, the height of each of the beam elements 124A, 124B, 124C, and 124D gradually decreases from both ends toward the center.

[0057] In this embodiment, the second fastening plate 42a is a press-formed product. In this case, by forming it into the shape described above, it is possible to suppress a situation in which the thickness of the central side of each beam element 124A, 124B, 124C, 124D becomes thin. If the height of each beam element 124A, 124B, 124C, 124D is the same over the entire length in the longitudinal direction, for example, the four beam elements 124A, 124B, 124C, 124D are closer to each other at the central side in the longitudinal direction as shown in FIG. 2, so that the thickness size at the central side is likely to be thinner than the thickness size at the fastening portion side. If the thickness size becomes thin, cracks are likely to occur, and the surface pressure pressing the cell stack 10 is likely to become uneven. In contrast, if the height of the center side of each of the beam elements 124A, 124B, 124C, and 124D is made lower than the height of the fastening portion side, as in the present embodiment, the wall thickness size at the center side does not become thin, cracks are less likely to occur, and the surface pressure pressing the cell stack 10 can be made uniform. Also, the total amount of material used for each of the beam elements 124A, 124B, 124C, and 124D can be reduced, resulting in weight reduction.

[0058] Furthermore, a portion formed by adjacent fastening portions and the beam element located therebetween may be formed so that the height changes continuously from one fastening portion to the other fastening portion.

[0059] The fastening parts 424A, 424B, 424C, and 424D each have a flange 126A, 126B, 126C, and 126D that is flush with the outer pressing part 110 at an edge facing the cell stack 10. By providing the flanges 126A, 126B, 126C, and 126D, the contact area between the first fastening plate 41a and the second fastening plate 42a can be increased. The through holes 424A1, 424B1, 424C1, and 424D1 are provided on the upper surface (the surface opposite the cell stack 10) at the tip side of the fastening parts 424A, 424B, 424C, and 424D.

[0060] The second clamping plate 42a is made of, for example, 2 mm thick high tensile steel (tensile strength 400 MPa) as a base material, and is integrally molded from a single plate through multiple pressure pressing processes using a mold. In this case, the plate thickness of the second clamping plate 42a is 2 mm or less. The plate thickness of the second clamping plate 42a is not particularly limited, but from the viewpoint of workability, it is not good for the base material to be too thick or too thin. From this viewpoint, the plate thickness of the second clamping plate 42a may be 1.5 mm or more and 3 mm or less, or 2 mm or more and 3 mm or less. The plate thickness can be measured by a known measuring means.

[0061] As described above, when the plate thickness of the second fastening plate 42a is relatively small, it is advantageous in terms of weight reduction and workability, but on the other hand, the rigidity of the second fastening plate 42a is small. Specifically, the bending rigidity of the second fastening plate 42a is smaller than the bending rigidity of the first fastening plate 41a.

[0062] Here, if the rigidity of the second clamping plate 42a is reduced, the second clamping plate 42a will bend during fastening, and for example, the central portion will be easily lifted. In contrast, in this embodiment, a convex inner pressing portion 115 is provided on the central portion, and the inner pressing portion 115 is separated from the outer pressing portion 110 by a recess 120A. Moreover, the inner pressing portion 115 protrudes from the outer pressing portion 110 before fastening. As a result, the second clamping plate 42a is bent and comes into contact with a wide range of the first clamping plate 41a. On the other hand, since the second clamping plate 42a comes into partial contact with the first clamping plate 41a, a distributed surface pressure is transmitted from the second clamping plate 42a to the first clamping plate 41a. However, the first clamping plate 41a is a flat plate, and has a flat portion 411 that comes into surface contact with the first insulating plate 30a. This allows a uniform surface pressure to be applied from the first fastening plate 41a to the cell stack 10 side.

[0063] <Actions and Effects> Next, the operation and effect of this embodiment will be described.

[0064] When assembling the fuel cell 1, first, the first current collector plate 20a is placed on one end face in the stacking direction St of the cell stack 10, and the second current collector plate 20b is placed on the other end face in the stacking direction St of the cell stack 10. Next, the first insulating plate 30a is placed on the first current collector plate 20a in the stacking direction St, and the second insulating plate 30b is placed on the second current collector plate 20b in the stacking direction St.

[0065] Next, the first clamping plate 41a and the second clamping plate 42a are arranged in this order on the first insulating plate 30a, and the first clamping plate 41b and the second clamping plate 42b are arranged in this order on the second insulating plate 30b. Then, fastening members 50 are provided between the fastening parts 424A, 424B, 424C, and 424D of the second clamping plate 42a and the fastening parts 424A, 424B, 424C, and 424D of the second clamping plate 42b, respectively, and the second clamping plate 42a and the second clamping plate 42b are clamped by the fastening members 50 so as to approach each other.

[0066] As described above, when the fastening member 50 is fastened, the second fastening plates 42a, 42b are easily bent, and for example, the central portion is easily lifted. In contrast, in the present embodiment, a convex inner pressing portion 115 is provided on the central side of the second fastening plates 42a, 42b, and the inner pressing portion 115 is separated from the outer pressing portion 110 by the recess 120A. Moreover, the inner pressing portion 115 protrudes from the outer pressing portion 110 before fastening. As a result, the second fastening plates 42a, 42b are bent and come into contact with a wide range of the first fastening plate 41a.

[0067] On the other hand, the second clamping plates 42a, 42b are in partial contact with the first clamping plate 41a at the outer pressing portion 110 and the inner pressing portion 115, so that a distributed surface pressure is transmitted from the second clamping plates 42a, 42b to the first clamping plates 41a, 41b. However, the first clamping plates 41a, 41b are flat and have flat portions 411 that come into surface contact with the insulating plates 30a, 30b. This allows the first clamping plates 41a, 41b to apply a uniform surface pressure to the cell stack 10. In other words, it is possible to prevent the insulating plate 30, the current collecting plate 20, and the cell stack 10 from being damaged by stress concentration due to the clamping force.

[0068] The fuel cell 1 according to the present embodiment described above includes a cell stack 10 in which a plurality of fuel cell cells 10c are stacked, a current collector plate 20 arranged on the cell stack 10, an insulating plate 30 arranged on the current collector plate 20, and a fastening structure 40 arranged on the insulating plate 30 and fastened to the cell stack 10 to hold the current collector plate 20 and the insulating plate 30 to the cell stack 10. The fastening structure 40 includes a first fastening plate 41 having a flat portion 411 that comes into surface contact with the insulating plate 30, and a second fastening plate 42 arranged on the first fastening plate 41 and fastened to the cell stack 10 to press the first fastening plate 41 against the insulating plate 30. This allows the second fastening plate 42 to apply a uniform surface pressure to the cell stack 10 even if the fastening plate (specifically, the second fastening plate 42) is deflected. The uniform surface pressure can suppress contact resistance, improving the performance of the fuel cell 1.

[0069] In addition, in the fastening structure 40, the plate-like first fastening plate 41 ensures rigidity, so the second fastening plate 42 can be made thinner, reducing its weight. Furthermore, by making the second fastening plate 42 thinner in the integral molding, workability is improved and press molding costs can be reduced. Furthermore, by making the second fastening plate 42 thinner, it is possible to absorb expansion and contraction during fastening, thereby preventing damage to the fuel cell 10c and preventing a decrease in the fastening force.

[0070] In this embodiment, the second fastening plate 42 has fastening portions 424A, 424B, 424C, and 424D that protrude from the outer periphery of the first fastening plate 41 when viewed in the stacking direction St, and the second fastening plate 42 is fastened to the cell stack 10 by a force applied in the stacking direction St from the fastening portions 424A, 424B, 424C, and 424D. The first fastening plate 41 is formed with notches 412A, 412B, 412C, and 412D that extend in a direction opposite to the protruding direction of the fastening portions 424A, 424B, 424C, and 424D. More specifically, the notches 412A, 412B, 412C, and 412D are provided at the four corners of the first fastening plate 41. In this case, when the fastening portions 424A, 424B, 424C, 424D bend toward the cell stack 10 when the second fastening plate 42 is fastened, the fastening portions 424A, 424B, 424C, 424D and their flanges 126A, 126B, 126C, 126D that bend significantly can be prevented from coming into contact with the first fastening plate 41. This makes it possible to prevent localized stress concentration in the first fastening plate 41, and allows the second fastening plate 42 to apply a more uniform surface pressure to the cell stack 10.

[0071] Note that there already exists a fuel cell in which a cell stack is sandwiched between two clamping plates. The first clamping plate 41 in the present embodiment described above may be additionally provided to such an existing fuel cell, thereby allowing the clamping force of the existing fuel cell to be adjusted. That is, in this case, first, a step of removing the fastening plate is performed. Next, a step of providing an additional fastening plate (corresponding to first fastening plate 41) having a flat portion that comes into surface contact with the insulating plate is performed on the insulating plate. Then, the clamping plate is placed on the additional clamping plate and clamped to the cell stack side, thereby pressing the additional clamping plate against the insulating plate, thereby holding the current collecting plate and the insulating plate to the cell stack.

[0072] Although one embodiment and a modified example have been described above, the above embodiment is presented as an example and is not intended to limit the scope of the invention. This new embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above-mentioned embodiment and other modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0073] For example, in the above embodiment, the fuel cell 1 has been described, but in another embodiment, the above-mentioned fastening structure 40 may be applied to an electrochemical device (electrolysis device) that functions as a hydrogen production device or the like. In this case, the electrochemical device includes a cell stack in which a plurality of electrochemical cells are stacked, a current collector plate arranged on the cell stack in the stacking direction of the electrochemical cells, an insulating plate arranged on the current collector plate, and a fastening structure arranged on the insulating plate and fastened to the cell stack side to hold the current collector plate and the insulating plate to the cell stack. The fastening structure includes a first fastening plate having a flat portion that makes surface contact with the insulating plate, and a second fastening plate arranged on the first fastening plate and fastened to the cell stack side to press the first fastening plate against the insulating plate. The arrangement of the manifold is not limited to the above-mentioned embodiment. For example, a structure having a manifold having an inlet and an outlet and an opposing manifold facing the manifold through the cell stack may be adopted. In this case, gas from the inlet flows into the opposing manifold through the cell stack, turns, and flows to the outlet side through the cell stack. [Explanation of symbols]

[0074] 1... fuel cell, 10... cell stack, 10c... fuel cell cell, 20... current collector plate, 20a... first current collector plate, 20b... second current collector plate, 30... insulating plate, 30a... first insulating plate, 30b... second insulating plate, 40... clamping structure, 40a... first clamping structure, 40b... second clamping structure, 41 (41a, 41b)... first clamping plate, 411... flat portion, 412A, 412B, 412C, 412D... notch, 42 (42a, 42b)... second clamping plate, 420... plate main body portion, 424A, 424B, 424C, 424D... fastening portion, 424A1, 424B1, 424C1, 424D1... through hole, 50... fastening member, 52 ...Stud bolt, 54...Washer, 56...Nut, 60...Manifold unit, 61...Oxidant electrode inlet manifold, 62...Oxidant electrode outlet manifold, 63...Anode inlet manifold, 64...Anode outlet manifold, 65...Separator, 66...Anode flow path, 110...Outer pressing portion, 110A...First side portion, 110B...Second side portion, 110C...Third side portion, 110D...Fourth side portion, 115...Inner pressing portion, 120...Beam portion, 120A...Recess, 124A...First beam element, 124B...Second beam element, 124C...Third beam element, 124D...Fourth beam element, 126A, 126B, 126C, 126D...Flange portion

Claims

1. a cell stack formed by stacking a plurality of fuel cell units; a current collector plate disposed on the cell stack in the stacking direction of the fuel cell units; an insulating plate disposed on the current collector plate; a fastening structure that is disposed on the insulating plate and fastened to the cell stack to hold the current collector plate and the insulating plate to the cell stack, The fastening structure includes a first fastening plate having a flat portion that is in surface contact with the insulating plate, and a second fastening plate that is disposed on the first fastening plate and is fastened to the cell stack side to press the first fastening plate against the insulating plate, The second clamping plate has a fastening portion that protrudes to the outer circumferential side of the first clamping plate when viewed in the stacking direction, and is fastened to the cell stack side by a force applied in the stacking direction from the fastening portion, A fuel cell, wherein the first fastening plate is provided with a notch extending in a direction opposite to a protruding direction of the fastening portion.

2. The fuel cell according to claim 1 , wherein the bending stiffness of the first fastening plate is greater than the bending stiffness of the insulating plate.

3. The second clamping plate has an outer pressing portion formed along an outer periphery and an inner pressing portion provided closer to the center than the outer pressing portion, The outer pressing portion and the inner pressing portion are each in contact with the first fastening plate, 3. The fuel cell according to claim 1, wherein a recess is provided between the outer pressing portion and the inner pressing portion, the recess being recessed toward a side opposite to the cell stack.

4. 4. The fuel cell according to claim 3, wherein the second fastening plate is configured such that, when separated from the cell stack, the inner pressing portion protrudes in the thickness direction beyond the outer pressing portion.

5. The second clamping plate has a connection portion that connects the outer pressing portion and the inner pressing portion, 5. The fuel cell according to claim 3, wherein a cross-sectional shape of said connection portion in a thickness direction is U-shaped, and said recess is formed by an inner surface of said U-shaped connection portion.

6. 6. The fuel cell according to claim 3, wherein the second clamping plate has a fastening portion on the outer circumferential side of the outer pressing portion, and is fastened to the cell stack side by a force applied from the fastening portion in the stacking direction.

7. The first clamping plate has a rectangular shape, and the fastening portions protrude from four corners of the first clamping plate, 7. The fuel cell according to claim 1, wherein the notches are provided at four corners of the first fastening plate.

8. 8. The fuel cell according to claim 1, wherein the second fastening plate is a press-molded product.

9. 9. The fuel cell according to claim 1, wherein the second fastening plate has a thickness of 3 mm or less.

10. A cell stack in which a plurality of electrochemical cells are stacked; a current collector plate disposed on the cell stack in a stacking direction of the electrochemical cells; an insulating plate disposed on the current collector plate; a fastening structure that is disposed on the insulating plate and fastened to the cell stack to hold the current collector plate and the insulating plate to the cell stack, The fastening structure includes a first fastening plate having a flat portion that is in surface contact with the insulating plate, and a second fastening plate that is disposed on the first fastening plate and is fastened to the cell stack side to press the first fastening plate against the insulating plate, The second clamping plate has a fastening portion that protrudes to the outer circumferential side of the first clamping plate when viewed in the stacking direction, and is fastened to the cell stack side by a force applied in the stacking direction from the fastening portion, The electrochemical device, wherein the first fastening plate is provided with a notch extending in a direction opposite to a protruding direction of the fastening portion.

11. A method for adjusting a fastening of a fuel cell comprising: a cell stack in which a plurality of fuel cell units are stacked; a current collector plate disposed on the cell stack in a stacking direction of the fuel cell units; an insulating plate disposed on the current collector plate; and a fastening plate disposed on the insulating plate and fastened to the cell stack to hold the current collector plate and the insulating plate to the cell stack, the method comprising the steps of: removing the clamping plate; providing an additional fastening plate on the insulating plate, the additional fastening plate having a flat portion that is in surface contact with the insulating plate; and a step of placing the fastening plate on the additional fastening plate and fastening it to the cell stack side to press the additional fastening plate against the insulating plate, thereby holding the current collecting plate and the insulating plate to the cell stack, The fastening plate has a fastening portion that protrudes to the outer circumferential side of the additional fastening plate when viewed in the stacking direction, and is fastened to the cell stack side by a force applied in the stacking direction from the fastening portion, The additional fastening plate is provided with a notch extending in a direction opposite to the protruding direction of the fastening portion,

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