Fuel cell, electrochemical device, and method for tightening adjustment of fuel cell

Abstract

The embodiment provides a fuel cell capable of imparting a uniform surface pressure to a single cell stack from a fastening plate even when a deflection is generated on the fastening plate. The fuel cell of the embodiment includes a single cell stack (10) in which a plurality of fuel cell single cells are stacked; a current collecting plate (20) disposed on the single cell stack (10) in a stacking direction of the fuel cell single cells; an insulating plate (30) disposed on the current collecting plate (20); and a fastening structure (40) disposed on the insulating plate (30) and holding the current collecting plate (20) and the insulating plate (30) to the single cell stack (10) by being fastened to the single cell stack (10) side. The fastening structure (40) includes a first fastening plate (41) having a flat surface portion in contact with a surface of the insulating plate (30), and a second fastening plate (42) disposed on the first fastening plate (41) and pressing the first fastening plate (41) against the insulating plate (30) by being fastened to the single cell stack (10) side.

Description

[0001] [REFERENCE TO RELATED APPLICATIONS]

[0002] This application claims priority to Japanese Patent Application No. 2021-135899 (Filing date: August 23, 2021) as a base application. The entire contents of the base application are incorporated herein by reference. TECHNICAL FIELD

[0003] Embodiments of the present application relate to a fuel cell, an electrochemical device, and a tightening adjustment method for a fuel cell. BACKGROUND

[0004] An electrochemical device such as a fuel cell, an electrolytic device, etc. is known. A fuel cell is a device that extracts electric energy from a fuel such as hydrogen by causing the fuel to chemically react with an oxidizing agent such as air.

[0005] As an example of a fuel cell, there is a fuel cell that has a single cell stack in which a plurality of fuel cell single cells are stacked, a pair of current collecting plates, a pair of insulating plates, and a pair of fastening plates.

[0006] In the fuel cell of the above type, the pair of current collecting plates, the pair of insulating plates, and the pair of fastening plates are arranged so as to sandwich the single cell stack. The current collecting plate, the insulating plate, and the fastening plate on one side are arranged in that order on an end surface on one side in the stacking direction of the single cell stack. The current collecting plate, the insulating plate, and the fastening plate on the other side are arranged in that order on an end surface on the other side in the stacking direction of the single cell stack. Further, the pair of fastening plates are fastened so as to approach each other by a fastening material that spans the pair of fastening plates. As a result, the components are integrated.

[0007] The fastening plate described above generally has a plurality of protruding portions that protrude toward the outer circumferential side of the single cell stack. Further, a fastening position is set for each of the protruding portions. Further, when the pair of fastening plates are fastened so as to approach each other, the fastening plates receive a fastening force at each of the fastening positions. At this time, the fastening plates are likely to float, for example, the central portion thereof, due to flexing accompanying the fastening.

[0008] In a fuel cell that uses a fastening plate, it is preferable to make the surface pressure of the fastening plate with respect to the single cell stack uniform in a manner that the contact resistance between adjacent fuel cell single cells does not become large. However, the floating described above can hinder the uniformization of the surface pressure.

[0009] As a structure of a fastening plate, a structure that has a plurality of beams combined in a manner that they cross each other, a structure that is considered to be integrally molded with a mold from the viewpoint of simplification of components, etc. are known.

[0010] Regarding the fastening plate of a structure having a plurality of beams, by increasing the plate thickness or providing a plurality of ribs, it is possible to suppress the above-mentioned floating by increasing rigidity. However, the shape and structure become complicated, and thus there is a possibility that the cost increases.

[0011] On the other hand, in the case of the fastening plate of the integrally formed structure, the plate thickness is generally restricted to several mm or so from the viewpoint of workability (work limit) of stamping, bending. Thus, it is difficult to ensure rigidity. Therefore, in the fastening plate of the integrally formed structure, by providing a protrusion toward the single cell stack side at a position where floating is likely to occur at the time of fastening, sometimes uniformization of the surface pressure to the single cell stack is achieved.

[0012] However, in the fastening plate having the above-mentioned protrusion, the surface pressure to the insulating plate is different, for example, at the protrusion and around thereof. In this case, it is generally possible to apply a pressure having a distribution from the fastening plate to the single cell stack via the current collecting plate and the insulating plate which have low rigidity. Thus, even in the fastening plate having the protrusion, there is room for improvement regarding the uniformization of the surface pressure. SUMMARY

[0013] The technical problem to be solved by the present application is to provide a fuel cell, an electrochemical device, and a fastening adjustment method of a fuel cell, in which even if deflection occurs in a fastening plate, a uniform surface pressure can be applied from the fastening plate to a single cell stack.

[0014] The fuel cell of one embodiment has a single cell stack in which a plurality of fuel cell single cells are stacked, a current collecting plate that is provided to the single cell stack in a stacking direction of the fuel cell single cells, an insulating plate that is provided to the current collecting plate, and a fastening structure that is provided to the insulating plate and holds the current collecting plate and the insulating plate to the single cell stack by being fastened to the single cell stack side. The fastening structure has a first fastening plate that has a planar portion that makes surface contact with the insulating plate, and a second fastening plate that is provided to the first fastening plate and presses the first fastening plate to the insulating plate by being fastened to the single cell stack side.

[0015] The electrochemical device of one embodiment has a single cell stack in which a plurality of electrochemical single cells are stacked, a current collecting plate that is provided to the single cell stack in a stacking direction of the electrochemical single cells, an insulating plate that is provided to the current collecting plate, and a fastening structure that is provided to the insulating plate and holds the current collecting plate and the insulating plate to the single cell stack by being fastened to the single cell stack side. The fastening structure has a first fastening plate that has a planar portion that makes surface contact with the insulating plate, and a second fastening plate that is provided to the first fastening plate and presses the first fastening plate to the insulating plate by being fastened to the single cell stack side.

[0016] The method for fastening adjustment of a fuel cell according to one embodiment includes a cell stack in which a plurality of fuel cell cells are stacked, a current collecting plate disposed on the cell stack in a stacking direction of the fuel cell cells, an insulating plate disposed on the current collecting plate, and a fastening plate disposed on the insulating plate, the current collecting plate and the insulating plate being held to the cell stack by being fastened to the cell stack side. The method includes a step of detaching the fastening plate, a step of disposing an additional fastening plate having a flat surface portion in surface contact with the insulating plate on the insulating plate, and a step of disposing the fastening plate on the additional fastening plate and fastening to the cell stack side, thereby pressing the additional fastening plate to the insulating plate, and holding the current collecting plate and the insulating plate to the cell stack.

[0017] [Effects of Invention]

[0018] According to the present application, even if a deflection occurs in the fastening plate, a uniform surface pressure can be applied from the fastening plate to the cell stack. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a perspective view of a fuel cell according to one embodiment.

[0020] Figure 2 FIG. 2 is an exploded perspective view of the fuel cell shown in FIG. 1. Figure 1 FIG. 3 is an exploded perspective view of the fuel cell shown in FIG. 1.

[0021] Figure 3 FIG. 4 is a schematic view of a flow path structure in the cell stack of the fuel cell shown in FIG. 1. Figure 1 FIG. 5 is a view showing a first fastening plate in a fastening structure included in the fuel cell shown in FIG. 1.

[0022] Figure 4 FIG. 6 is a view showing a second fastening plate in the fastening structure included in the fuel cell shown in FIG. 1. Figure 1 FIG. 7 is a cross-sectional view of the second fastening plate before fastening shown in FIG. 6.

[0023] Figure 5 FIG. 8 is a cross-sectional view of the second fastening plate after fastening shown in FIG. 6. Figure 1 FIG. 9 is a cross-sectional view of the second fastening plate after fastening shown in FIG. 6.

[0024] Figure 6 FIG. 10 is a cross-sectional view of the second fastening plate after fastening shown in FIG. 6. Figure 5 FIG. 11 is a cross-sectional view of the second fastening plate after fastening shown in FIG. 6.

[0025] Figure 7 FIG. 12 is a cross-sectional view of the second fastening plate after fastening shown in FIG. 6. Figure 5 FIG. 13 is a cross-sectional view of the second fastening plate after fastening shown in FIG. 6. DETAILED DESCRIPTION

[0026] Hereinafter, a fuel cell 1 as an example of an electrochemical device according to an embodiment will be described with reference to the drawings.

[0027] <Overall structure of fuel cell>

[0028] Figure 1 is a perspective view of the fuel cell 1 according to an embodiment. Figure 2 is an exploded perspective view of the fuel cell 1. Figure 1 and Figure 2 The fuel cell 1 shown in FIGS. 1 and 2 is a device that generates electricity by electrochemical reactions occurring in fuel cell cells 10c (see FIG. 3) included in a cell stack 10. Figure 2

[0029] The fuel cell 1 includes the cell stack 10, a pair of current collecting plates 20, a pair of insulating plates 30, a pair of fastening structures 40, a fastening member 50, and a manifold unit 60.

[0030] As shown in FIG. 1, the cell stack 10 is configured by stacking fuel cell cells 10c as a plurality of electrochemical cells. The fuel cell cells 10c generate electricity by electrochemical reactions of a fuel gas containing hydrogen and air (oxidizer) containing oxygen, for example. In addition, Figure 2 Figure 1 and Figure 2 The reference sign St in FIGS. 1 and 2 indicates a direction in which the fuel cell cells 10c are stacked (hereinafter, referred to as a stacking direction).

[0031] The fuel cell cell 10c has, for example, a junction body configured by sandwiching an electrolyte membrane with a fuel electrode and an oxidizer electrode, and a separator that forms flow paths for supplying fuel and oxidizer to the junction body. The separator can be configured by a conductive porous plate having fine pores, for example. In addition, a cooling water flow path can be provided in the separator. In addition, the outer shape of the illustrated cell stack 10 is a rectangular parallelepiped shape, but can be a cubic shape, and can be another hexahedron or another three-dimensional shape.

[0032] The pair of current collecting plates 20 is configured by a first current collecting plate 20a and a second current collecting plate 20b. The first current collecting plate 20a is disposed on an end surface on one side (an upper side in FIGS. 1 and 2) in the stacking direction St of the cell stack 10. The second current collecting plate 20b is disposed on an end surface on the other side (a lower side in FIGS. 1 and 2) in the stacking direction St of the cell stack 10. Figure 1 Figure 2 Figure 1 Figure 2

[0033] ​​​​​​The first and second current collecting plates 20a and 20b are rectangular plate-shaped conductors, for example, members for sending electric power generated by the single cell stack 10 to the outside. The first and second current collecting plates 20a and 20b are formed in the same or similar shape as the rectangular end surface of the single cell stack 10. The first and second current collecting plates 20a and 20b are generally composed of a metal plate, but can be any conductors. The first and second current collecting plates 20a and 20b can also be composed of a graphite plate, for example.

[0034] 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 collecting plate 20a in the stacking direction St. The second insulating plate 30b is disposed on the second current collecting plate 20b in the stacking direction St. The first and second insulating plates 30a and 30b are rectangular plate-shaped insulators, for example, composed of a synthetic resin plate. In detail, the first and second insulating plates 30a and 30b are formed in the same or similar rectangular shape as the opposing first or second current collecting plate 20a or 20b.

[0035] The pair of fastening structures 40 is composed of a first fastening structure 40a and a second fastening structure 40b. The first fastening structure 40a is disposed on the first insulating plate 30a in the stacking direction St. The second fastening structure 40b is disposed on the second insulating plate 30b in the stacking direction St. The first and second fastening structures 40a and 40b each have a first fastening plate 41 and a second fastening plate 42. Hereinafter, the first fastening plate 41 in the first fastening structure 40a is denoted by a first fastening plate 41a, and the second fastening plate 42 in the first fastening structure 40a is denoted by a second fastening plate 42a. The first fastening plate 41 in the second fastening structure 40b is denoted by a first fastening plate 41b, and the second fastening plate 42 in the second fastening structure 40b is denoted by a second fastening plate 42b.

[0036] The first fastening plates 41a and 41b are each a plate-shaped member disposed between the corresponding insulating plate 30a or 30b and the corresponding second fastening plate 42a or 42b. In the present embodiment, the first fastening plates 41a and 41b are the same shape as each other, and the second fastening plates 42a and 42b are also the same shape as each other. In the following description, the same reference numerals are assigned to the same members among the components of the first fastening plates 41a and 41b, and the same reference numerals are also assigned to the same members among the components of the second fastening plates 42a and 42b.

[0037] However, the first fastening plates 41a and 41b can not necessarily be the same shape as each other, and the second fastening plates 42a and 42b can not necessarily be the same shape as each other.

[0038] AsFigure 1 and Figure 2 As shown in FIG. 6, the second fastening plates 42a, 42b each have a plurality of fastening portions 424A, 424B, 424C, 424D that project toward the outer periphery side of the first fastening plates 41a, 41b when viewed in the stacking direction St. In detail, the fastening portions 424A, 424B, 424C, 424D also project toward the outer periphery side of the single cell stack 10, the current collecting plate 20, the insulating plate 30, and the manifold unit 60. Note that the "projecting toward the outer periphery side" referred to herein means, for example, projecting outward beyond the first fastening plates 41a, 41b and the like in a direction orthogonal to the stacking direction St.

[0039] As shown in FIG. 6, the second fastening plates 42a, 42b each have a plurality of fastening portions 424A, 424B, 424C, 424D that project toward the outer periphery side of the first fastening plates 41a, 41b when viewed in the stacking direction St. In detail, the fastening portions 424A, 424B, 424C, 424D also project toward the outer periphery side of the single cell stack 10, the current collecting plate 20, the insulating plate 30, and the manifold unit 60. Note that the "projecting toward the outer periphery side" referred to herein means, for example, projecting outward beyond the first fastening plates 41a, 41b and the like in a direction orthogonal to the stacking direction St. Figure 2 As shown in FIG. 6, the second fastening plates 42a, 42b each have a plurality of fastening portions 424A, 424B, 424C, 424D that project toward the outer periphery side of the first fastening plates 41a, 41b when viewed in the stacking direction St. In detail, the fastening portions 424A, 424B, 424C, 424D also project toward the outer periphery side of the single cell stack 10, the current collecting plate 20, the insulating plate 30, and the manifold unit 60. Note that the "projecting toward the outer periphery side" referred to herein means, for example, projecting outward beyond the first fastening plates 41a, 41b and the like in a direction orthogonal to the stacking direction St.

[0040] The fastening member 50 in the present embodiment includes a stud bolt 52, a pair of washers 54, and a pair of nuts 56. One end portion of the stud bolt 52 passes through the through hole 424A1, 424B1, 424C1, 424D1 of the second fastening plate 42a, and the other end portion of the stud bolt 52 passes through the through hole 424A1, 424B1, 424C1, 424D1 of the second fastening plate 42b. Further, the washer 54 and the nut 56 are respectively attached to the one end portion and the other end portion of the stud bolt 52.

[0041] In the attached state of the fastening member 50 described above, at least either one of the nut 56 on the one end portion side of the stud bolt 52 and the nut 56 on the other end portion side of the stud bolt 52 is fastened to the single cell stack 10 side, whereby the second fastening plates 42a, 42b are fastened to the single cell stack 10 side with the force added to 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 single cell stack 10. Note that the details of the structure of the first fastening plates 41a, 41b and the second fastening plates 42a, 42b will be described later.

[0042] The manifold unit 60 is as shown in FIG. 7. Figure 1As shown, the manifold unit 60 is disposed around the single cell stack 10. The manifold unit 60 has an oxidant electrode inlet manifold 61, an oxidant electrode outlet manifold 62, a fuel electrode inlet manifold 63, and a fuel electrode outlet manifold 64.

[0043] As described above, the fuel cell single cell 10c has, for example, a junction body composed of a fuel electrode and an oxidant electrode sandwiching an electrolyte membrane, and a separator forming flow paths for supplying fuel and oxidant to the junction body. In this case, in the separator, a fuel electrode flow path is formed on one face, and an oxidant electrode flow path is formed on the other face.

[0044] Figure 3 is a schematic view illustrating the flow path structure in the single cell stack 10. In Figure 3 Each of the manifolds 61 to 64, the separator 65 constituting the fuel cell unit 10c, and the fuel electrode flow path 66 formed in the separator 65 are shown in

[0045] The fuel electrode inlet manifold 63 and the fuel electrode outlet manifold 64 face each other across the single cell stack 10. Further, the fuel electrode inlet manifold 63 and the fuel electrode outlet manifold 64 are fluidly connected to the fuel electrode flow path 66. When power generation is performed, hydrogen-containing fuel (fuel gas) flows in unshown pipe portions, enters the fuel electrode inlet manifold 63, passes through the fuel electrode flow path 66, flows in unshown pipe portions from the fuel electrode outlet manifold 64, and is discharged to the outside. Oxidant flows in unshown pipe portions, enters the oxidant electrode inlet manifold 61, passes through unshown oxidant electrode flow paths on the separator, flows in unshown pipe portions from the oxidant electrode outlet manifold 62, and is discharged to the outside.

[0046] <Structure of fastening structure>

[0047] Hereinafter, the first fastening plates 41a, 41b and the second fastening plates 42a, 42b in the fastening structure 40 will be described in detail. In the present embodiment, the first fastening plates 41a, 41b are identical in shape to each other, and the second fastening plates 42a, 42b are also identical in shape to each other. Therefore, for the convenience of explanation, the first fastening plate 41a and the second fastening plate 42a will be described hereinafter, and the description of the first fastening plate 41b and the second fastening plate 42b will be omitted.

[0048] (First fastening plate)

[0049] The first fastening plate 41a is a plate-like member as described above, and is disposed between the corresponding first insulating plate 30a and the corresponding second fastening plate 42a. Figure 4 is a view showing the first fastening plate 41a as viewed from the side where the single cell stack 10 is located. As shown in Figure 2 and Figure 4As shown, the first fastening plate 41a is a generally rectangular plate with a planar portion 411 that contacts the surface of the first insulating plate 30a.

[0050] In this embodiment, the first fastening plate 41a is formed to a size that is included within the first insulating plate 30a when it overlaps with the facing first insulating plate 30a. Therefore, in this embodiment, the main surface of the first fastening plate 41a on the first current collector 20a side is entirely a planar portion 411. Furthermore, in this embodiment, since the first fastening plate 41a is included within the first insulating plate 30a, the first fastening plate 41a is smaller than the first insulating plate 30a. In this case, the planar portion 411 preferably contacts at least 90% of the surface area including the center of the first insulating plate 30a. On the other hand, the planar portion 411 can be formed to be larger than the first insulating plate 30a, allowing it to contact the entire surface of the first insulating plate 30a.

[0051] The first fastening plate 41a is made of a component with higher strength than the first insulating plate 30a. Specifically, the bending stiffness of the first fastening plate 41a is greater than that of the first insulating plate 30a. The first fastening plate 41a can be made of, for example, a metal sheet or a high-strength resin sheet, but its material is not particularly limited.

[0052] Furthermore, cutouts 412A, 412B, 412C, and 412D are formed at the four corners of the first fastening plate 41a. When viewed along the stacking direction St, the fastening portions 424A, 424B, 424C, and 424D of the second fastening plate 42a extend outward from the four corners of the first fastening plate 41a. In contrast, the cutouts 412A, 412B, 412C, and 412D extend in the opposite direction to the extension direction of the corresponding fastening portions 424A, 424B, 424C, and 424D. By providing such cutouts 412A, 412B, 412C, and 412D, the surface pressure when the fastening portions 424A, 424B, 424C, and 424D, which flex during fastening, come into contact with the first fastening plate 41a is alleviated. In addition, in this embodiment, when the first fastening plate 41a overlaps with the facing first insulating plate 30a, the periphery of the first fastening plate 41a becomes a state along the periphery of the first insulating plate 30a except for the cut portion.

[0053] In this embodiment, such as Figure 4 As shown, cuts 412A, 412B, 412C, and 412D are formed in an L-shape, but their shape is not particularly limited. Cuts 412A, 412B, 412C, and 412D can also be rectangular, chamfered, or concave towards the center. Alternatively, cuts 412A, 412B, 412C, and 412D may not be formed.

[0054] (Second fastening plate)

[0055] The second fastening plate 42a is arranged on the first fastening plate 41a and is fastened to the single cell stack 10 side via the fastening portions 424A, 424B, 424C, 424D described above, thereby pressing the first fastening plate 41a against the first insulating plate 30a. Figure 5 is a view of the second fastening plate 42a as viewed from the side on which the single cell stack 10 is arranged.

[0056] As shown in Figure 2 and Figure 5 , the second fastening plate 42a has a plate main body portion 420 that is substantially rectangular in plan view, and the fastening portions 424A, 424B, 424C, 424D described above that project from the four corners of the plate main body portion 420. The plate main body portion 420 is a portion that overlaps the first fastening plate 41a when fastened. Figure 6 is a sectional view of the second fastening plate 42a before fastening, and is a sectional view along the VI-VI line of Figure 2 . Figure 7 is a sectional view corresponding to Figure 6 , and is a sectional view of the second fastening plate 42a after fastening.

[0057] Referring also to Figure 6 and Figure 7 , the plate main body portion 420 is not flat in shape, but has a concave-convex shape. As shown in Figure 1 and Figure 2 , the plate main body portion 420 has an outer side pressing portion 110 that is formed along the outer periphery, an inner side pressing portion 115 that is provided at a position closer to the center than the outer side pressing portion 110, and a beam portion 120 that is a connecting portion connecting the outer side pressing portion 110 and the inner side pressing portion 115, the beam portion 120 being raised with respect to the outer side pressing portion 110 and the inner side pressing portion 115 to form a concave-convex shape.

[0058] The outer side pressing portion 110 and the inner side 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 single cell stack 10 side. That is, the outer side pressing portion 110 and the inner side pressing portion 115 press the first insulating plate 30a via the first fastening plate 41a.

[0059] On the other hand, the beam portion 120 is a portion that does not come into contact with the first fastening plate 41a. As shown in Figure 6 and Figure 7 , the cross-sectional shape of the beam portion 120 in the thickness direction is U-shaped. The U-shaped beam portion 120 has a recessed portion 120A formed on the inner surface thereof. The recessed portion 120A is recessed toward the side opposite to the single cell stack 10 side, and thus the beam portion 120 does not come into contact with the first fastening plate 41a even in the case where the second fastening plate 42b is fastened to the single cell stack 10 side.

[0060] If the outer pressing portion 110 and the inner pressing portion 115 are described in more detail, in the present embodiment, as shown in Figure 6 the inner pressing portion 115 is more protruded in the thickness direction (stacking direction St) than the outer pressing portion 110 in a state where the second fastening plate 42a is separated from the single cell stack 10.

[0061] In Figure 6 , the protrusion amount At of the inner pressing portion 115 is exaggeratedly depicted, but the protrusion amount At can also be 25% or more and 40% or less of the thickness of the second fastening plate 42b, particularly 30% or more and 35% or less. More specifically, for example, in a case where the thickness of the second fastening plate 42b is 2 mm and is formed of high-tension steel, the protrusion amount At can also be 0.6 mm or more and 0.7 mm or less.

[0062] On the other hand, as shown in Figure 7 , in a state where the second fastening plate 42a is fastened to the single cell stack 10 side, both the inner pressing portion 115 and the outer pressing portion 110 are in contact with the first fastening plate 41a on the same face. In the second fastening plate 42a, the fastening portions 424A, 424B, 424C, 424D are located on the outer peripheral side of the outer pressing portion 110. Further, the second fastening plate 42a is fastened to the single cell stack 10 side by a force added to the stacking direction St from the fastening portions 424A, 424B, 424C, 424D.

[0063] In the case of fastening as described above, the inner pressing portion 115 in the second fastening plate 42a, which is located on the central side than the outer pressing portion 110, is easily floated to the side opposite to the single cell stack 10 side. Here, as described above, in a case where the inner pressing portion 115 is more protruded in the thickness direction than the outer pressing portion 110 in a state where the second fastening plate 42a is separated from the single cell stack 10, a state where the inner pressing portion 115 and the outer pressing portion 110 are in contact with the first fastening plate 41a can be formed when the second fastening plate 42a is fastened to the single cell stack 10 side. Thereby, it is possible to uniformly apply the pressing force from the second fastening plate 42a to the first fastening plate 41a, and it is possible to avoid local stress concentration. In addition, the preferable value of the protrusion amount At of the inner pressing portion 115 with respect to the outer pressing portion 110 varies depending on the thickness and the material of the second fastening plate 42b.

[0064] The outer pressing portion 110 is formed in a manner of following the four sides of the substantially rectangular plate main portion 420, as shown in Figure 2As shown, the inner side pressing portion 115 is configured so as to be surrounded by the first edge portion 110A, the second edge portion 110B, the third edge portion 110C, and the fourth edge portion 110D. The inner side 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.

[0065] The beam portion 120 is a portion whose cross-sectional shape in the thickness direction is U-shaped as described above, and specifically has a first beam element 124A, a second beam element 124B, a third beam element 124C, and a fourth beam element 124D connected in a manner that forms a substantially rectangular four sides on the inner peripheral side of the outer side 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 cross-sectional shape in the thickness direction orthogonal to the length direction that is U-shaped. The first beam element 124A, the second beam element 124B, the third beam element 124C, and the fourth beam element 124D are arranged in point symmetry with respect to the central position of the inner side pressing portion 115.

[0066] In the present embodiment, the beam portion 120 is connected to the fastening portions 424A, 424B, 424C, and 424D. Specifically, at the joining portion of 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 cross-sectional shape that is U-shaped, join the inner wall portions of each other toward the inner side pressing portion 115 side, and on the other hand, extend the outer wall portions of each toward the corner portions of the plate main body portion 420 without joining, in a manner along the diagonal line of the plate main body portion 420. Furthermore, the outer wall portion of the first beam element 124A that extends in a manner along the diagonal line of the plate main body portion 420 is connected to the upper end of the outer wall portion of the second beam element 124B, and a cross-sectional shape that is U-shaped is formed. Furthermore, 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 extend toward the direction of extension of the diagonal line of the plate main body portion 420. The fastening portion 424A has a cross-sectional shape that is U-shaped, and connects the U-shaped cross-sections formed by the outer wall portions of the first beam element 124A and the second beam element 124B in a continuous manner.

[0067] The fastening portion 424B is connected to the joining portion of the second beam element 124B and the third beam element 124C in the same manner as the connection described above. The fastening portion 424C is connected to the joining portion of the third beam element 124C and the fourth beam element 124D. The fastening portion 424D is connected to the joining portion of the fourth beam element 124D and the first beam element 124A.

[0068] As described above, beam portion 120 is connected to fastening portions 424A, 424B, 424C, and 424D, thereby creating a smooth continuity of beam elements between adjacent fastening portions. Here, the height of the central side of each beam element 124A, 124B, 124C, and 124D may be less than the height of the portions located on both sides of the fastening portions 424A, 424B, 424C, and 424D. In this embodiment, specifically, the height of each beam element 124A, 124B, 124C, and 124D gradually decreases from both ends towards the center.

[0069] In this embodiment, the second fastening plate 42a is a stamped product. In this case, by setting it to the shape described above, the thinning of the wall thickness on the central side of each beam element 124A, 124B, 124C, and 124D can be suppressed. Assuming that the height of each beam element 124A, 124B, 124C, and 124D is the same along its entire length, then... Figure 2 As shown, for example, the four beam elements 124A, 124B, 124C, and 124D are closer together at their central sides along the length direction, making it easy for the wall thickness at the central side to become thinner than that at the fastener side. If the wall thickness becomes thinner, cracking is more likely to occur, and the surface pressure applied to the single-cell laminate 10 is also more likely to become uneven. In contrast, as in this embodiment, if the height of the central side of each beam element 124A, 124B, 124C, and 124D is lower than the height at the fastener side, the wall thickness at the central side does not become thinner, cracking is less likely to occur, and the surface pressure applied to the single-cell laminate 10 can be made more uniform. Furthermore, the amount of material used in each beam element 124A, 124B, 124C, and 124D as a whole can be reduced, achieving weight reduction.

[0070] In addition, the portion consisting of adjacent fasteners and beam elements located therebetween can also be formed such that the height changes continuously from one fastener to the other.

[0071] Furthermore, fastening portions 424A, 424B, 424C, and 424D each have flange portions 126A, 126B, 126C, and 126D flush with the outer pressing portion 110 on their edges facing the single-cell stack 10. By providing flange portions 126A, 126B, 126C, and 126D, the contact area between the first fastening plate 41a and the second fastening plate 42a can be increased. Additionally, through holes 424A1, 424B1, 424C1, and 424D1 are provided on the upper surface of the front end side of fastening portions 424A, 424B, 424C, and 424D (the surface opposite to the single-cell stack 10 side).

[0072] The second fastening plate 42a is integrally formed from one steel sheet using a die through a multiple press working process, for example, using high-tension steel (tensile strength 400 MPa) having a thickness of 2 mm as a base material. In this case, the thickness of the second fastening plate 42a is 2 mm or less. The thickness of the second fastening plate 42a is not particularly limited, but from the viewpoint of workability, the base material is not good if it is too thick or too thin. From this viewpoint, the thickness of the second fastening plate 42a can be 1.5 mm or more and 3 mm or less, or 2 mm or more and 3 mm or less. The thickness can be measured using a publicly known measuring means.

[0073] As described above, in the case where the thickness of the second fastening plate 42a is small, it is advantageous in terms of weight reduction and workability, but on the other hand, the rigidity of the second fastening plate 42a becomes small. Specifically, the bending rigidity of the second fastening plate 42a is smaller than the bending rigidity of the first fastening plate 41a.

[0074] Here, in the case where the rigidity of the second fastening plate 42a is small, the second fastening plate 42a is deflected at the time of fastening, and for example, the portion on the central side is likely to float up. In contrast to this, in the present embodiment, the inner side pressing portion 115 is provided on the central side in a convex shape, and the inner side pressing portion 115 is separated from the outer side pressing portion 110 by the recessed portion 120A. Further, the inner side pressing portion 115 is more protruding than the outer side pressing portion 110 in the state before fastening. Thus, the second fastening plate 42a is brought into contact with the first fastening plate 41a in a wide range as deflected. On the other hand, since the second fastening plate 42a is locally in contact with the first fastening plate 41a, a surface pressure having a distribution is transmitted from the second fastening plate 42a to the first fastening plate 41a. However, the first fastening plate 41a has the flat surface portion 411 which is a flat plate shape and which is in surface contact with the first insulating plate 30a. Thus, it is possible to impart a uniform surface pressure from the first fastening plate 41a to the single cell stack 10 side.

[0075] <Effects>

[0076] Next, the effects of the present embodiment will be described.

[0077] In assembling the fuel cell 1, first, the first current collecting plate 20a is disposed on the end surface on one side in the stacking direction St of the single cell stack 10, and the second current collecting plate 20b is disposed on the end surface on the other side in the stacking direction St of the single cell stack 10. Next, the first insulating plate 30a is disposed on the first current collecting plate 20a in the stacking direction St, and the second insulating plate 30b is disposed on the second current collecting plate 20b in the stacking direction St.

[0078] Next, the first fastening plate 41a and the second fastening plate 42a are arranged on the first insulating plate 30a in this order, and the first fastening plate 41b and the second fastening plate 42b are arranged on the second insulating plate 30b in this order. Further, the fastening members 50 are provided between the fastening portions 424A, 424B, 424C, 424D of the second fastening plate 42a and the fastening portions 424A, 424B, 424C, 424D of the second fastening plate 42b, respectively, and the second fastening plate 42a and the second fastening plate 42b are fastened to be close to each other by the fastening members 50.

[0079] When the connecting member 50 is fastened as described above, the second fastening plates 42a, 42b are easily deflected, and, for example, the portions on the central side are easily raised. In contrast, in the present embodiment, the convex inner side pressing portions 115 are provided on the central side of the second fastening plates 42a, 42b, and the inner side pressing portions 115 are separated from the outer side pressing portions 110 by the recessed portions 120A. Further, the inner side pressing portions 115 protrude more than the outer side pressing portions 110 in the state before fastening. Thus, the second fastening plates 42a, 42b are brought into contact with a wide range of the first fastening plate 41a as deflection.

[0080] On the other hand, since the second fastening plates 42a, 42b are in contact with the first fastening plate 41a locally at the outer side pressing portions 110 and the inner side pressing portions 115, surface pressure having a distribution is transmitted from the second fastening plates 42a, 42b to the first fastening plates 41a, 41b. However, the first fastening plates 41a, 41b have the flat surface portions 411 which are flat plate-shaped and in surface contact with the insulating plates 30a, 30b. Thus, it is possible to impart uniform surface pressure from the first fastening plates 41a, 41b to the single cell stack 10 side. That is, it is possible to prevent the insulating plates 30, the current collecting plates 20, and the single cell stack 10 from being damaged or the like due to stress concentration caused by the fastening force.

[0081] The fuel cell 1 of the above-described embodiment has the single cell stack 10 in which a plurality of fuel cell single cells 10c are stacked, the current collecting plate 20 arranged on the single cell stack 10, the insulating plate 30 arranged on the current collecting plate 20, and the fastening structure 40 arranged on the insulating plate 30 and holding the current collecting plate 20 and the insulating plate 30 to the single cell stack 10 by being fastened to the single cell stack 10 side. Further, the fastening structure 40 has the first fastening plate 41 having the flat surface portions 411 in surface contact with the insulating plate 30, and the second fastening plate 42 arranged on the first fastening plate 41 and pressing the first fastening plate 41 to the insulating plate 30 by being fastened to the single cell stack 10 side. Thus, even if deflection occurs in the fastening plate (in detail, the second fastening plate 42), it is possible to impart uniform surface pressure from the second fastening plate 42 to the single cell stack 10. Further, it is possible to suppress the contact resistance by the uniformization of the surface pressure, and it is possible to improve the performance of the fuel cell 1.

[0082] Further, in the fastening structure 40, rigidity can be ensured by the first fastening plate 41 which is plate-shaped, and thus the second fastening plate 42 can be made thin in thickness, and the weight can be reduced. Also, if the thickness of the second fastening plate 42 is made thin in the integral molding, the workability is improved, and the cost of the press molding can be reduced. Further, by making the second fastening plate 42 thin and the like, the second fastening plate 42 is easily deflected, and thus the expansion and contraction at the time of fastening can be absorbed, and thus the breakage of the fuel cell single cells 10c can be suppressed, and the reduction of the fastening force can also be suppressed.

[0083] Further, in the present embodiment, the second fastening plate 42 has fastening portions 424A, 424B, 424C, 424D which project to the outer circumferential side of the first fastening plate 41 when viewed in the stacking direction St, and the second fastening plate 42 is fastened to the single cell stack 10 side by the force added to the fastening portions 424A, 424B, 424C, 424D in the stacking direction St. Also, the first fastening plate 41 is formed with notches 412A, 412B, 412C, 412D which extend in the direction opposite to the projection direction of the fastening portions 424A, 424B, 424C, 424D. In detail, the notches 412A, 412B, 412C, 412D are provided at the four corners of the first fastening plate 41. In this case, when the fastening portions 424A, 424B, 424C, 424D are deflected to the single cell stack 10 side at the time of fastening of the second fastening plate 42, the portions of the fastening portions 424A, 424B, 424C, 424D, the flange portions 126A, 126B, 126C, 126D, which are more deflected, are prevented from coming into contact with the first fastening plate 41. Thus, the stress concentration can be prevented from locally occurring in the first fastening plate 41, and the uniform surface pressure can be applied from the second fastening plate 42 to the single cell stack 10.

[0084] Further, there is a fuel cell in which the single cell stack is sandwiched by two fastening plates. The first fastening plate 41 of the above-described present embodiment can also be additionally provided to such a conventional fuel cell, and thus the fastening force of the conventional fuel cell can also be adjusted. That is, in this case, first, a process of detaching the fastening plates is performed. Next, a process of providing an additional fastening plate (corresponding to the first fastening plate 41) having a flat surface portion which makes surface contact with the insulating plate on the insulating plate is performed. Then, a process of arranging the above-described fastening plates on the additional fastening plate and fastening to the single cell stack side, thereby pressing the additional fastening plate to the insulating plate and holding the current collecting plate and the insulating plate to the single cell stack is performed.

[0085] The above describes one embodiment and modifications, but the above-described embodiment is presented as an example and is not intended to limit the scope of the invention. The new embodiment can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. The above-described embodiment and other modifications are included in the scope or spirit of the invention and are included in the scope of the invention as recited in the claims and equivalents thereof.

[0086] For example, in the above-described embodiment, the fuel cell 1 is described, but as another embodiment, the above-described fastening structure 40 can be appropriately used for an electrochemical device (electrolytic device) that functions as a hydrogen manufacturing device or the like. In this case, the electrochemical device is provided with: a single cell stack in which a plurality of electrochemical single cells are stacked; a current collecting plate disposed on the single cell stack in a stacking direction of the electrochemical single cells; an insulating plate disposed on the current collecting plate; and a fastening structure disposed on the insulating plate, which holds the current collecting plate and the insulating plate on the single cell stack by being fastened to the single cell stack side. Also, the fastening structure has: a first fastening plate having a flat surface portion in surface contact with the insulating plate; and a second fastening plate disposed on the first fastening plate, which presses the first fastening plate against the insulating plate by being fastened to the single cell stack side. The configuration of the manifold is not limited to the above-described embodiment. For example, a structure having a manifold having an inlet and an outlet and an opposite manifold opposite the manifold across the single cell stack can be employed. In this case, gas from the inlet flows into the opposite manifold via the single cell stack to turn around and flows toward the outlet side via the single cell stack.

[0087] [Legend of Reference Numerals]

[0088] 1…fuel cell, 10…single cell stack, 10c…fuel cell single cell, 20…collector plate, 20a…first collector plate, 20b…second collector plate, 30…insulating plate, 30a…first insulating plate, 30b…second insulating plate, 40…fastening structure, 40a…first fastening structure, 40b…second fastening structure, 41(41a, 41b)…first fastening plate, 411…flat portion, 412A, 412B, 412C, 412D…cutout, 42(42a, 42b)…second fastening 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…fuel electrode inlet manifold, 64…fuel electrode outlet manifold, 65…separator, 66…fuel electrode flow path, 110…outer pressing portion, 110A…first edge portion, 110B…second edge portion, 110C…third edge portion, 110D…fourth edge 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 fuel cell comprising: a cell stack in which a plurality of fuel cell cells are stacked; a current collector plate disposed on the cell stack in a stacking direction of the fuel cell cells; and an insulating plate disposed on the current collector plate. and a fastening structure provided on the insulating plate and retaining the current collecting plate and the insulating plate to the single cell stack by being fastened to the single cell stack side, the fastening structure having: a first fastening plate having a flat surface portion in surface contact with the insulating plate; and a second fastening plate provided on the first fastening plate and pressing the first fastening plate to the insulating plate by being fastened to the single cell stack side, the second fastening plate having a fastening portion protruding to the outer periphery side of the first fastening plate when viewed in the stacking direction, being fastened to the single cell stack side by a force applied to the stacking direction from the fastening portion, and being provided with a cutout extending in a direction opposite to the protruding direction of the fastening portion on the first fastening plate.

2. The fuel cell according to claim 1, the first fastening plate having a bending rigidity greater than a bending rigidity of the insulating plate.

3. The fuel cell according to claim 2, the second fastening plate having: an outer pressing portion formed in a manner following the outer periphery of the second fastening plate; and an inner pressing portion provided at a position more centrally than the outer pressing portion, the outer pressing portion and the inner pressing portion each being in contact with the first fastening plate, and a recessed portion being provided between the outer pressing portion and the inner pressing portion and recessed to a side opposite to the single cell stack side.

4. The fuel cell according to claim 3, the second fastening plate being configured such that, in a state of being separated from the single cell stack, the inner pressing portion protrudes more in a thickness direction than the outer pressing portion.

5. The fuel cell according to claim 3, the second fastening plate having a connecting portion connecting the outer pressing portion and the inner pressing portion, a cross-sectional shape of the connecting portion in the thickness direction being U-shaped, and the recessed portion being formed by an inner surface of the U-shaped connecting portion.

6. The fuel cell according to claim 3, the second fastening plate having a fastening portion on the outer periphery side of the outer pressing portion, the fastening portion being fastened to the single cell stack side by a force applied to the stacking direction from the fastening portion.

7. The fuel cell according to claim 1, the first fastening plate being rectangular, the fastening portion protruding from four corners of the first fastening plate, and the cutout being provided at the four corners of the first fastening plate.

8. The fuel cell according to any one of claims 1 to 7, the second fastening plate being a press-formed product.

9. The fuel cell according to any one of claims 1 to 7, the second fastening plate having a thickness of 3 mm or less.

10. An electrochemical device comprising: a single cell stack in which a plurality of electrochemical single cells are stacked; a current collecting plate disposed on the single cell stack in a stacking direction of the electrochemical single cells; and an insulating plate disposed on the current collecting plate. and a fastening structure provided on the insulating plate and retaining the current collecting plate and the insulating plate to the single cell stack by being fastened to the single cell stack side, the fastening structure having: a first fastening plate having a flat surface portion in surface contact with the insulating plate; and a second fastening plate configured on the first fastening plate, the second fastening plate pressing the first fastening plate against the insulating plate by being fastened to the single cell stack side, the second fastening plate having a fastening portion that protrudes toward an outer periphery side of the first fastening plate when viewed in the stacking direction, the second fastening plate being fastened to the single cell stack side by a force applied from the fastening portion to the stacking direction, the first fastening plate being provided with a cutout that extends in a direction opposite to a protruding direction of the fastening portion.

11. A fastening adjustment method of a fuel cell that includes a single cell stack in which a plurality of fuel cell single cells are stacked, a current collecting plate that is disposed on the single cell stack in a stacking direction of the fuel cell single cells, an insulating plate that is disposed on the current collecting plate, and a fastening plate that is disposed on the insulating plate, the fastening plate holding the current collecting plate and the insulating plate to the single cell stack by being fastened to the single cell stack side, the fastening adjustment method of the fuel cell including a step of detaching the fastening plate, a step of disposing an additional fastening plate having a flat surface portion that makes surface contact with the insulating plate on the insulating plate, and a step of disposing the fastening plate on the additional fastening plate and fastening to the single cell stack side, thereby pressing the additional fastening plate against the insulating plate and holding the current collecting plate and the insulating plate to the single cell stack, the fastening plate having a fastening portion that protrudes toward an outer periphery side of the additional fastening plate when viewed in the stacking direction, the fastening plate being fastened to the single cell stack side by a force applied from the fastening portion to the stacking direction, the additional fastening plate being provided with a cutout that extends in a direction opposite to a protruding direction of the fastening portion.

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