Fuel cell stack

Abstract

The present invention relates to a fuel cell stack. The fuel cell stack (10) comprises: a single cell stack (14) which is formed by stacking a plurality of power generation cells (12), wherein the power generation cells are formed by sandwiching an electrolyte membrane-electrode structure (28) between a separator (26); and a stack casing (16) which accommodates the single cell stack (14).

Description

Technical Field

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

[0002] Generally speaking, a fuel cell stack is constructed to include a single cell stack and an end panel. The single cell stack is composed of a plurality of stacked power generation cells. The power generation cell has an electrolyte membrane-electrode structure and a separator that clamps the electrolyte membrane-electrode structure. The end panels are arranged at both ends of the stacking direction of the single cell stack. Such a fuel cell stack can be used for vehicle-mounted purposes, for example. That is, the fuel cell stack can be mounted on a movable carrier such as a fuel cell vehicle for use. The fuel cell stack used for vehicle-mounted purposes as described above is particularly susceptible to external loads associated with the movement of the vehicle. Therefore, a fuel cell stack such as that described in Patent Document 1 is known. The fuel cell stack includes a stack casing that accommodates the single cell stack to protect the single cell stack from external loads and the like.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-185498 Summary of the invention

[0006] In a fuel cell stack including a stack case that accommodates a unit cell stack, it is desired to suppress an increase in the weight of the stack case and to increase the rigidity of the stack case so as to better protect the unit cell stack.

[0007] The object of the present invention is to solve the above-mentioned problems.

[0008] One embodiment of the present invention is a fuel cell stack comprising: a single cell stack having a plurality of power generation cells, which is formed by stacking a plurality of the power generation cells, wherein the power generation cells are formed by sandwiching an electrolyte membrane-electrode structure with a separator; and a stack shell, which accommodates the single cell stack, wherein in the fuel cell stack, the bottom plate of the stack shell has a concave-convex shape.

[0009] In the fuel cell stack, a concave-convex shape is provided on the bottom plate of the stack shell. As a result, the overall thickness of the bottom plate can be kept from increasing (suppressing the increase in the weight of the stack shell) and the rigidity of the stack shell can be improved. In this way, in the stack shell with improved rigidity, deformation can be suppressed even when an external load is applied to the fuel cell stack. Therefore, deformation of the single cell stack accommodated in the stack shell can be suppressed. As a result, the single cell stack can be effectively protected from the influence of external loads.

[0010] The following embodiments will be described with reference to the accompanying drawings, and the above-mentioned objects, features, and advantages will be easily understood based on the description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a partially exploded perspective view of a fuel cell stack according to an embodiment of the present invention.

[0012] Figure 2 This is an exploded perspective view of a power generation cell.

[0013] Figure 3 It is a diagram illustrating the MEA side surface of the second bipolar plate.

[0014] Figure 4 It is a partial cross-sectional view of a fuel cell stack.

[0015] Figure 5 yes Figure 1 The cross-sectional view is shown in the direction of the arrow on line VV. DETAILED DESCRIPTION

[0016] In the following drawings, the same reference numerals are given to structural elements that achieve the same or similar functions and effects, and repeated descriptions may be omitted.

[0017] Figure 1 The fuel cell stack 10 of the present embodiment shown can be preferably used as a vehicle mounted on a vehicle such as a fuel cell car (not shown). Therefore, the fuel cell stack 10 for vehicle use is described below as an example, but is not particularly limited to this. The fuel cell stack 10 can also be used as a fixed installation type.

[0018] The fuel cell stack 10 includes: a cell stack 14, which is formed by stacking a plurality of power generation cells 12; and a stack case 16, which accommodates the cell stack 14. At one end of the stacking direction (arrow A direction) of the cell stack 14, a connection plate 18a, an insulating member 20a, and an end plate 22a are sequentially arranged outward. In addition, at the other end of the stacking direction of the plurality of power generation cells 12, a connection plate 18b, an insulating member 20b, and an end plate 22b are sequentially arranged outward.

[0019] The insulating members 20a and 20b are formed of insulating materials such as polycarbonate (PC) and phenolic resin. Furthermore, the insulating members 20a and 20b may each be composed of a plurality of (for example, two) components overlapping in the stacking direction. In addition, although not shown in the figure, a recessed recess 92 may be formed on the surface of the insulating member 20a facing the single cell stack 14 in a manner away from the single cell stack 14. In this case, a terminal plate 18a is arranged in the recess 92. Alternatively, a recessed recess 92 may be formed on the surface of the insulating member 20b facing the single cell stack 14 in a manner away from the single cell stack 14. In this case, a terminal plate 18b is arranged in the recess 92.

[0020] The power generation cell 12 is, for example, in a rectangular shape with the direction of arrow symbol B as the long side direction and the direction of arrow symbol C as the short side direction. In the cell stack 14, the long side direction of the power generation cell 12 is the width direction (the direction orthogonal to the stacking direction and the up-down direction) of the cell stack 14. In addition, in the present embodiment, the length of the cell stack 14 in the stacking direction (the direction of arrow symbol A) is longer than the long side of the power generation cell 12.

[0021] like Figure 2 As shown, the power generation cell 12 has an MEA 24 with a resin frame and a group of separators 26 that sandwich the MEA 24 with a resin frame. In the MEA 24 with a resin frame, the periphery of the electrolyte membrane-electrode structure (MEA) 28 is surrounded by a resin frame member 30. The electrolyte membrane-electrode structure 28 has an electrolyte membrane 32, an anode electrode 34, and a cathode electrode 36. The anode electrode 34 is provided on one surface of the electrolyte membrane 32. The cathode electrode 36 is provided on the other surface of the electrolyte membrane 32.

[0022] The electrolyte membrane 32 is, for example, a solid polymer electrolyte membrane (cation exchange membrane) such as a thin film of perfluorosulfonic acid containing water. The electrolyte membrane 32 is sandwiched between the anode electrode 34 and the cathode electrode 36. In addition, as the electrolyte membrane 32, in addition to the fluorine-based electrolyte, an HC (hydrocarbon) electrolyte can also be used.

[0023] The anode electrode 34 has an anode electrode catalyst layer and an anode gas diffusion layer, both of which are not shown. The anode electrode catalyst layer is bonded to one surface of the electrolyte membrane 32. The anode gas diffusion layer is stacked on the anode electrode catalyst layer. The cathode electrode 36 has a cathode electrode catalyst layer and a cathode gas diffusion layer, both of which are not shown. The cathode electrode catalyst layer is bonded to the other surface of the electrolyte membrane 32. The cathode gas diffusion layer is stacked on the cathode electrode catalyst layer.

[0024] The anode electrode catalyst layer is formed, for example, by uniformly coating the surface of the anode gas diffusion layer with porous carbon particles carrying a platinum alloy and an ion conductive polymer binder. The cathode electrode catalyst layer is formed, for example, by uniformly coating the surface of the cathode gas diffusion layer with porous carbon particles carrying a platinum alloy and an ion conductive polymer binder.

[0025] The cathode gas diffusion layer and the anode gas diffusion layer are respectively formed of conductive porous sheets such as carbon paper or carbon cloth. Alternatively, a porous layer (not shown) may be provided between at least one of the cathode electrode catalyst layer and the cathode gas diffusion layer and between the anode electrode catalyst layer and the anode gas diffusion layer.

[0026] The resin frame member 30 is frame-shaped. For example, the inner peripheral edge of the resin frame member 30 is joined to the outer peripheral edge of the electrolyte membrane-electrode structure 28. By setting the resin frame member 30 on the electrolyte membrane-electrode structure 28 in this way, for example, the area of ​​the electrolyte membrane 32 required to form one power generation cell 12 can be reduced. The electrolyte membrane 32 is relatively expensive. Therefore, by reducing the area of ​​the electrolyte membrane 32 required to form one power generation cell 12, the material cost of the electrolyte membrane-electrode structure 28 can be reduced.

[0027] The joining structure of the resin frame member 30 and the electrolyte membrane-electrode structure 28 is not limited to the above-mentioned structure. In one example of the joining structure of the resin frame member 30 and the electrolyte membrane-electrode structure 28, the inner peripheral edge of the resin frame member 30 can be clamped between the outer peripheral edge of the cathode gas diffusion layer and the outer peripheral edge of the anode gas diffusion layer. In this case, the inner peripheral end surface of the resin frame member 30 can be close to the outer peripheral end surface of the electrolyte membrane 32, can be in contact with the outer peripheral end surface of the electrolyte membrane 32, or can overlap with the outer peripheral end surface of the electrolyte membrane 32.

[0028] In another example of the bonding structure of the resin frame member 30 and the electrolyte membrane-electrode structure 28, the outer peripheral edge of the electrolyte membrane 32 protrudes outward compared to the cathode gas diffusion layer and the anode gas diffusion layer. Frame-shaped films are provided on both sides of the outer peripheral edge of the electrolyte membrane 32. A plurality of frame-shaped films are stacked in a manner sandwiching the electrolyte membrane 32. The stacked frame-shaped films are bonded to each other by an adhesive or the like to form the resin frame member 30.

[0029] like Figure 1As shown, at one end of the long side direction of the power generation cell 12, the end plate 22a, and the insulating members 20a and 20b, the oxidant gas inlet communication hole 38a, the cooling medium inlet communication hole 40a, and the fuel gas outlet communication hole 42b are arranged in the vertical direction. At the other end of the long side direction of the power generation cell 12, the end plate 22a, and the insulating members 20a and 20b, the fuel gas inlet communication hole 42a, the cooling medium outlet communication hole 40b, and the oxidant gas outlet communication hole 38b are arranged in the vertical direction.

[0030] The oxidant gas inlet passage 38a is supplied with an oxidant gas (e.g., an oxygen-containing gas). The cooling medium inlet passage 40a is supplied with a cooling medium (e.g., at least one of pure water, ethylene glycol, and oil). The fuel gas (e.g., a hydrogen-containing gas) is discharged from the fuel gas outlet passage 42b. The fuel gas is supplied to the fuel gas inlet passage 42a. The cooling medium is discharged from the cooling medium outlet passage 40b. The oxidant gas is discharged from the oxidant gas outlet passage 38b.

[0031] The oxidant gas inlet communication holes 38a provided in each power generation cell 12, the end plate 22a, and the insulating members 20a, 20b in the cell stack 14 are connected to each other in the stacking direction. That is, the oxidant gas inlet communication holes 38a penetrate the end plate 22a, the insulating members 20a, 20b, and the cell stack 14 in the stacking direction. Similarly, the cooling medium inlet communication holes 40a, the fuel gas outlet communication holes 42b, the fuel gas inlet communication holes 42a, the cooling medium outlet communication holes 40b, and the oxidant gas outlet communication holes 38b also penetrate the end plate 22a, the insulating members 20a, 20b, and the cell stack 14 in the stacking direction.

[0032] In this embodiment, an example is shown in which, in each power generation cell 12, the oxidant gas inlet connecting hole 38a, the cooling medium inlet connecting hole 40a, the fuel gas outlet connecting hole 42b, the fuel gas inlet connecting hole 42a, the cooling medium outlet connecting hole 40b, and the oxidant gas outlet connecting hole 38b (hereinafter, they are also simply collectively referred to as "connecting holes") are provided one by one. However, the number of each connecting hole provided in each power generation cell 12 is not particularly limited, and it can be either single or multiple. In addition, the shape and configuration of each connecting hole are not limited to Figure 1 and Figure 2 The contents of this embodiment described in can be appropriately set according to the required specifications.

[0033] like Figure 2As shown, the separator 26 is formed by stacking a first bipolar plate 50 and a second bipolar plate 52. The outer periphery of the first bipolar plate 50 and the outer periphery of the second bipolar plate 52 are joined together in a mutually stacked state, for example, by welding, brazing, caulking, etc. The first bipolar plate 50 and the second bipolar plate 52 are each formed, for example, by stamping a cross section of a thin metal plate into a wavy shape. As an example of the thin metal plate, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, a titanium plate, or a plate whose metal surface is subjected to a surface treatment for corrosion prevention can be listed. In addition, the first bipolar plate 50 and the second bipolar plate 52 can also be each made of a carbon material.

[0034] In addition, the separator 26 is not limited to the separator formed by joining the first bipolar plate 50 and the second bipolar plate 52. For example, the separator 26 may be formed of a metal plate. The separator 26 may be formed of a carbon plate. Alternatively, an insulating resin material may be provided on the outer edge of the separator 26.

[0035] The first bipolar plate 50 has an MEA side surface 50a which is a surface facing the MEA 24 with a resin frame, and a refrigerant side surface 50b which is a back side of the MEA side surface 50a. The second bipolar plate 52 has an MEA side surface 52a which is a surface facing the MEA 24 with a resin frame, and a refrigerant side surface 52b which is a back side of the MEA side surface 52a.

[0036] A plurality of protrusions extending linearly in the direction of arrow symbol B are provided on the MEA side surface 50a of the first bipolar plate 50. These protrusions form linear oxidant gas flow paths 54 in the grooves between each other. Furthermore, the protrusions and the oxidant gas flow paths 54 may each be wavy. The oxidant gas flow paths 54 are connected to the oxidant gas inlet communication holes 38a and the oxidant gas outlet communication holes 38b so that the oxidant gas can flow along the surface direction of the separator 26 (the direction of arrow symbols B and C).

[0037] In addition, the MEA 24 ( Figure 2 For example, the first bipolar plate 50 is stamped to form the metal protruding seal 56a integrally provided on the first bipolar plate 50. Alternatively, a convex elastic seal formed of an elastic material may be provided on the MEA side 50a instead of the metal protruding seal 56a.

[0038] A portion of the metal protrusion seal 56a of the first bipolar plate 50 surrounds the oxidant gas flow path 54, the oxidant gas inlet communication hole 38a, and the oxidant gas outlet communication hole 38b as a whole. On the inner side surrounded by the metal protrusion seal 56a, the oxidant gas flow path 54, the oxidant gas inlet communication hole 38a, and the oxidant gas outlet communication hole 38b are connected to each other. In addition, the other portion of the metal protrusion seal 56a surrounds the fuel gas inlet communication hole 42a, the fuel gas outlet communication hole 42b, the coolant inlet communication hole 40a, and the coolant outlet communication hole 40b individually. Thus, the metal protrusion seal 56a prevents the fuel gas and the coolant from flowing into the oxidant gas flow path 54.

[0039] like Figure 3 As shown, a plurality of protrusions extending linearly in the direction of arrow symbol B are provided on the MEA side surface 52a of the second bipolar plate 52. These protrusions form a linear fuel gas flow path 58 in the grooves between each other. In addition, the protrusions and the fuel gas flow path 58 may each be wavy. The fuel gas flow path 58 is connected to the fuel gas inlet connecting hole 42a and the fuel gas outlet connecting hole 42b so that the fuel gas can flow along the surface direction of the separator 26 (the direction of arrow symbols B and C).

[0040] In addition, the MEA side surface 52a of the second bipolar plate 52 is provided with a MEA 24 ( Figure 2 ) The metal protruding seal 56b protrudes from the second bipolar plate 52. For example, the second bipolar plate 52 is stamped and formed, thereby the metal protruding seal 56b is integrally provided on the second bipolar plate 52. Alternatively, a convex elastic seal formed of an elastic material may be provided on the MEA side 52a instead of the metal protruding seal 56b.

[0041] A portion of the metal protrusion seal 56b of the second bipolar plate 52 surrounds the fuel gas flow path 58, the fuel gas inlet communication hole 42a, and the fuel gas outlet communication hole 42b as a whole. On the inner side surrounded by the metal protrusion seal 56b, the fuel gas flow path 58, the fuel gas inlet communication hole 42a, and the fuel gas outlet communication hole 42b are connected to each other. In addition, the other portion of the metal protrusion seal 56b surrounds the oxidant gas inlet communication hole 38a, the oxidant gas outlet communication hole 38b, the coolant inlet communication hole 40a, and each coolant outlet communication hole 40b individually. Thus, the metal protrusion seal 56b prevents the oxidant gas and the coolant from flowing into the fuel gas flow path 58.

[0042] like Figure 2As shown, a cooling medium flow path 60 is provided between the refrigerant side surface 50b of the first bipolar plate 50 and the refrigerant side surface 52b of the second bipolar plate 52. The cooling medium flow path 60 is connected to the cooling medium inlet communication hole 40a and the cooling medium outlet communication hole 40b so that fluid can flow. Thus, the cooling medium flow path 60 allows the cooling medium to flow along the surface direction of the partition plate 26 (the direction of arrow symbols B and C).

[0043] The cooling medium flow path 60 is formed by overlapping the back shape of the oxidant gas flow path 54 of the first bipolar plate 50 with the back shape of the fuel gas flow path 58 of the second bipolar plate 52. In addition, the peripheral portion of the connecting hole of the refrigerant side surface 50b and the peripheral portion of the connecting hole of the refrigerant side surface 52b are joined by, for example, welding, brazing, etc. in a state where they face each other.

[0044] like Figures 2 to 4 As shown, each separator 26 is provided with a bottom protrusion 62 and an upper protrusion 64. The bottom protrusion 62 is arranged at the approximate center of the long side direction of the separator 26. The bottom protrusion 62 protrudes downward from the lower edge of the separator 26. In the present embodiment, the bottom protrusion 62 of each separator 26 is provided on each of the first bipolar plate 50 and the second bipolar plate 52. Thus, the bottom protrusion 62 of each separator 26 is formed by stacking two bottom protrusions in the stacking direction to form a set. However, the bottom protrusion 62 of each separator 26 may also be formed by only one bottom protrusion provided on either the first bipolar plate 50 or the second bipolar plate 52.

[0045] The bottom tab 62 can be formed of, for example, the same material as the first bipolar plate 50 and the second bipolar plate 52. For example, the bottom tab 62 is formed into a plate shape independent of the first bipolar plate 50 and then joined to the lower edge of the first bipolar plate 50 by welding or brazing. Similarly, for example, the bottom tab 62 is formed into a plate shape independent of the second bipolar plate 52 and then joined to the lower edge of the second bipolar plate 52 by welding or brazing. Furthermore, the bottom tab 62 may be formed integrally with the same base material as the first bipolar plate 50 and the second bipolar plate 52.

[0046] like Figure 4As shown, both ends of the bottom tab 62 in the direction of the arrow symbol B are each formed into a roughly triangular shape. In addition, the bottom tab 62 is a symmetrical shape based on the center line passing through the center of the bottom tab 62 in the direction of the arrow symbol B in the up-down direction. A positioning hole 66 is formed in the central part of the surface direction (arrow symbol B, C direction) of the bottom tab 62. A rod not shown in the figure can be inserted through the positioning hole 66 for positioning multiple power generation cells 12 when manufacturing the fuel cell stack 10 (when stacking multiple power generation cells 12). After the stacking of the multiple power generation cells 12 is completed, the rod can be pulled out from the positioning hole 66. However, it is also possible that the rod is left in the positioning hole 66 after the manufacturing of the fuel cell stack 10 is completed.

[0047] Alternatively, an insulating resin (not shown) may be provided on the outer periphery of the bottom protrusion 62 and the inner periphery of the positioning hole 66. The insulating resin in this case is not particularly limited as long as it has electrical insulation properties. Preferred examples of the insulating resin include polycarbonate, phenylene sulfide, polysulfone, fluororesin, and the same materials as those of the insulating members 20a and 20b.

[0048] The upper tab 64 is configured in substantially the same manner as the bottom tab 62 except for the following matters. Therefore, a detailed description of the upper tab 64 is omitted. The upper tab 64 is disposed near one end (the end in the direction of the arrow symbol B2) that is closer to the center in the long side direction of the partition 26. The upper tab 64 protrudes upward from the upper edge of the partition 26. The bottom tabs 62 and the upper tabs 64 provided in each power generation cell 12 are arranged in a row along the stacking direction of the cell stack 14, thereby forming a tab row.

[0049] Protrusions 68 protruding downward are provided at both ends in the long-side direction (direction of arrow symbol B) of each partition plate 26. Therefore, in the outer shape of the partition plate 26 except the bottom protrusion 62 and the upper protrusion 64 as viewed from the stacking direction, the vertical dimension (vertical length) of the two ends of the partition plate 26 in the horizontal direction is greater than the vertical dimension (vertical length) of the center portion in the horizontal direction. The lower end surface 68a of the protrusion 68 is arranged below the lower end surface 62a of the bottom protrusion 62.

[0050] like Figure 1As shown, the stack shell 16 is formed to include a peripheral wall shell 70 and end panels 22a, 22b. The peripheral wall shell 70 surrounds the outer periphery of the single cell stack 14 except for the two ends in the stacking direction. The end panels 22a, 22b are arranged at the two ends of the stacking direction of the single cell stack 14 as described above. That is, the end panels 22a, 22b constitute a part of the stack shell 16. In this embodiment, the peripheral wall shell 70 is a square tube shape with openings 72 provided at both ends in the stacking direction. Therefore, the peripheral wall shell 70 has an upper plate 74, a bottom plate 78, and a pair of side plates 76. In addition, the peripheral wall shell 70 is formed as an integral structure, for example, by extrusion molding, casting, etc.

[0051] The structure of the stack shell 16 is not particularly limited to the above content. For example, an opening (not shown) that exposes the single cell stack 14 may be provided on any one of the upper plate 74, a pair of side plates 76, and the bottom plate 78 of the peripheral wall shell 70. In this case, the stack shell 16 also has a closing plate (not shown) that can be detachably closed to close the opening. The closing plate is removed from the peripheral wall shell 70 to open the opening, thereby making it easy to reach the single cell stack 14 accommodated in the stack shell 16. Another form of the peripheral wall shell 70 may also be an upper plate, a bottom plate, and a pair of side plates that are independently formed. In this case, the upper plate, the pair of side plates, and the bottom plate are joined by bolts or the like to be assembled into a square tube-shaped peripheral wall shell 70.

[0052] The pair of end panels 22a and 22b sandwich the cell stack 14 accommodated in the peripheral wall case 70 in the stacking direction. In addition, the end panels 22a and 22b are each joined to the peripheral edge of the opening 72 of the peripheral wall case 70 by bolts 80. A sealing member 82 ( 20 ) formed of an elastic material is inserted and installed along the outer periphery of the opening 72 between each of the end panels 22a and 22b and the peripheral wall case 70. Figure 5 ).

[0053] As described above, each end panel 22a, 22b is mounted on the peripheral wall shell 70, thereby the opening 72 of the peripheral wall shell 70 is closed. Thus, a storage space is formed inside the stack shell 16. The single cell stack 14, the insulating members 20a, 20b and the terminal plates 18a, 18b are contained in the storage space while being clamped between a pair of end panels 22a, 22b. At this time, a stacking direction tightening load is applied to the single cell stack 14 by means of a pair of end panels 22a, 22b. Due to this tightening load, it is possible to suppress the leakage of fuel gas, etc. to the outside of the single cell stack 14 when the fuel cell stack 10 generates electricity. In addition, due to the tightening load, it is possible to apply appropriate surface pressure to the power generation surface of the power generation single cell 12. Moreover, the tightening load can be adjusted by adjusting the thickness of the insulating members 20a, 20b or configuring a pad (gasket), etc.

[0054] Furthermore, as described above, the outer peripheral surface of the cell stack 14 accommodated in the stack case 16 may be separated from the inner wall surface of the peripheral wall case 70 .

[0055] like Figure 4 As shown, the bottom plate 78 of the peripheral wall case 70 has a bottom plate inner surface 84 facing the cell stack 14, and a bottom plate outer surface 86, which is the back side of the bottom plate inner surface 84. In the bottom plate 78, the direction orthogonal to the thickness direction (up-down direction, arrow symbol C direction) of the bottom plate 78 and the stacking direction (arrow symbol A direction) of the cell stack 14 is set as the width direction (arrow symbol B direction).

[0056] The bottom plate 78 is provided with a concavo-convex shape 88. The concavo-convex shape 88 has a convex portion 90. The convex portion 90 is provided on the bottom plate inner surface 84 of the bottom plate 78 and protrudes toward the single cell stack 14. The convex portion 90 is a protrusion extending in the stacking direction at the approximate center in the width direction of the bottom plate 78. Moreover, the convex portion 90 observed from the bottom plate outer surface 86 of the bottom plate 78 is in the shape of a groove that sinks toward the single cell stack 14 and extends in the stacking direction.

[0057] In addition, the concavo-convex shape 88 has a concave portion 92. The concave portion 92 is provided on both sides of the bottom plate 78 in the width direction sandwiching the convex portion 90 and is provided integrally with the convex portion 90. The concave portion 92 observed from the bottom plate inner surface 84 of the bottom plate 78 is sunken in a manner away from the single cell stack 14. In addition, the concave portion 92 observed from the bottom plate inner surface 84 of the bottom plate 78 is a groove shape extending in the stacking direction. On the other hand, the concave portion 92 observed from the bottom plate outer surface 86 of the bottom plate 78 protrudes in a manner away from the single cell stack 14. In addition, the concave portion 92 observed from the bottom plate outer surface 86 of the bottom plate 78 is a ridge extending in the stacking direction. In the stack case 16, the protrusion 68 of each separator 26 of the single cell stack 14 protrudes toward the concave portion 92 of the bottom plate 78. A gap is formed between the bottom surface 92a of the bottom plate inner surface 84 having the concave portion 92 and the lower end surface 68a of the protrusion 68.

[0058] The thickness T1 of the center portion of the bottom plate 78 in the width direction is greater than the thickness T2 of both ends of the bottom plate 78 in the width direction. That is, the thickness of the portion of the bottom plate 78 where the protrusion 90 is formed is greater than the thickness of the portion of the bottom plate 78 where the recess 92 is formed.

[0059] like Figure 1 and Figure 4 As shown, a bottom support bar 94 is provided between the upper end surface 90a of the convex portion 90 of the bottom plate 78 and the lower end surface 62a of the bottom protrusion 62 (protrusion row) of the single cell stack 14. Figure 1 and Figure 5As shown, the bottom support bar 94 extends between the pair of end panels 22a and 22b in the stacking direction. Examples of materials for forming the bottom support bar 94 include metal materials (aluminum, iron, etc.) coated with insulating resin and insulating resin materials.

[0060] like Figure 1 and Figure 5 As shown, in this embodiment, one end portion (the end portion in the direction of arrow symbol A1) of the bottom support rod 94 in the extension direction is connected to the end panel 22a by means of a hollow positioning pin 96 and a connecting bolt 98. In this case, the one end surface 94a of the bottom support rod 94 and the end panel 22a are fixed in relative position in a state of abutting with no gap.

[0061] In addition, the other end of the bottom support rod 94 in the extension direction (the end in the direction of arrow symbol A2) is supported by the end panel 22b by a pair of solid pins 100. In this case, the bottom support rod 94 is supported by the end panel 22b so as to be relatively movable in the direction of arrow symbol A relative to the end panel 22b. Specifically, at the other end of the bottom support rod 94 in the extension direction, a pin insertion hole 102 is provided along the extension direction. The end of the pin 100 in the direction of arrow symbol A2 is fixed to the end panel 22b. On the other hand, the end of the pin 100 in the direction of arrow symbol A1 is movably engaged with the pin insertion hole 102 of the bottom support rod 94 in the axial direction. Moreover, the length of the bottom support rod 94 in the extension direction may be set to be slightly shorter than the distance between the pair of end panels 22a and 22b joined to the peripheral wall housing 70.

[0062] The other end face 94b of the bottom support rod 94 and the end panel 22b can approach each other in the direction of arrow symbol A. The other end face 94b of the bottom support rod 94 and the end panel 22b can be separated from each other with a gap provided therebetween. In addition, the other end face 94b of the bottom support rod 94 and the end panel 22b are restricted from relative movement in directions other than the direction of arrow symbol A (radial direction of the pin 100).

[0063] As described above, the other end surface 94b of the bottom support bar 94 is relatively movable in the stacking direction relative to the end panel 22b. Therefore, even if the bottom support bar 94 is provided between the pair of end panels 22a and 22b, it is possible to avoid a structure in which the bottom support bar 94 applies a tightening load to the single cell stack 14. As a result, the stacking direction rigidity required of the bottom support bar 94 can be reduced. Furthermore, the bottom support bar 94 can be made lighter.

[0064] like Figure 4As shown, a bottom tab insertion portion 104 is provided on the upper surface of the bottom support rod 94. The bottom tab insertion portion 104 is a concave shape for inserting the bottom tab 62. Both ends of the bottom tab 62 inserted into the bottom tab insertion portion 104 in the width direction abut against the inner wall surface 106 of the bottom tab insertion portion 104.

[0065] In this embodiment, the bottom protrusion insertion portion 104 is formed from one end of the bottom support rod 94 in the extending direction to the other end of the bottom support rod 94 in the extending direction. In addition, the bottom protrusion insertion portion 104 is a groove shape capable of accommodating the protrusion row of the bottom protrusion 62. Specifically, the bottom protrusion insertion portion 104 is formed by a base 108 and a group of rising portions 110. The base 108 has an upper surface 112. The upper surface 112 faces the lower end surface 62a of the bottom protrusion 62 inserted in the bottom protrusion insertion portion 104 at a distance in the up-down direction.

[0066] A set of rising portions 110 protrude from both sides of the base 108 in the width direction toward the cell stack 14. A bottom tab insertion portion 104 is provided between the set of rising portions 110. The set of rising portions 110 has inner peripheral surfaces (inner wall surfaces 106) facing each other in the width direction with the bottom tab 62 sandwiched therebetween. The pair of inner peripheral surfaces (inner wall surfaces 106) abut against both ends of the bottom tab 62 in the width direction.

[0067] An abutting surface 114 that abuts against the single cell stack 14 is provided at the upper end of the rising portion 110. Therefore, the bottom support rod 94 bears the weight of the single cell stack 14 via the abutting surface 114. By bearing the weight of the single cell stack 14 in this way, the bottom support rod 94 bends. As a result, the lower end surface of the bottom support rod 94 (base 108) abuts against the upper end surface 90a of the convex portion 90. Moreover, it is preferred that the corners at both ends in the width direction of the bottom tab insertion portion 104 (the connecting portion between the upper surface 112 and the inner wall surface 106) have a curved shape. It is preferred that the contact portion of the partition 26 that contacts the abutting surface 114 is covered with an insulating resin (not shown).

[0068] The upper plate 74 of the peripheral wall housing 70 includes a first upper plate portion 116, a second upper plate portion 118, and an inclined portion 120. The end of the inclined portion 120 in the direction of arrow symbol B2 is connected to the first upper plate portion 116. The end of the inclined portion 120 in the direction of arrow symbol B1 is connected to the second upper plate portion 118. The upper end surface of the first upper plate portion 116 is configured to be higher than the upper end surface of the second upper plate portion 118. Therefore, the inclined portion 120 connecting the first upper plate portion 116 and the second upper plate portion 118 is inclined relative to the width direction. The end of the inclined portion 120 in the direction of arrow symbol B2 is configured to be higher than the end of the inclined portion 120 in the direction of arrow symbol B1.

[0069] Since the first upper plate portion 116 is arranged above the second upper plate portion 118 as described above, a storage space is formed between the single cell stack 14 and the first upper plate portion 116 in the stack case 16. The upper protrusion 64, the upper support rod 122, and the bus bar (not shown) are accommodated in the storage space. On the other hand, a space for arranging, for example, an electric device unit (not shown) is formed above the second upper plate portion 118. The electric power generated by the power generation single cell 12 is supplied to the electric device unit via the above-mentioned bus bar.

[0070] The upper support bar 122 is disposed between the upper protrusion 64 (protrusion row) of the single cell stack 14 and the first upper plate portion 116 of the upper plate 74. The upper support bar 122 extends between the pair of end panels 22a and 22b in the stacking direction. The upper support bar 122 can be formed of the same material as the bottom support bar 94. In addition, similarly to the bottom support bar 94, one end of the upper support bar 122 in the extension direction is fixed to the end panel 22a, and the other end is supported by the end panel 22b so as to be relatively movable in the direction of arrow symbol A relative to the end panel 22b.

[0071] An upper tab insertion portion 124 is provided on the lower surface of the upper support rod 122. The upper tab insertion portion 124 is a concave shape for inserting the upper tab 64. The upper tab insertion portion 124 and the bottom tab insertion portion 104 can be constructed in the same manner except that the directions of the upper and lower directions are reversed. That is, the rising portion 110 forming the upper tab insertion portion 124 protrudes downward from the base 108. Moreover, the rising portion 110 of the upper tab insertion portion 124 may not have the abutting surface 114. That is, the lower end surface of the rising portion 110 of the upper tab insertion portion 124 may not abut against the single cell stack 14. At the upper tab insertion portion 124 of the upper support rod 122, both ends of the upper tab 64 in the width direction abut against the inner wall surface 106 of the upper tab insertion portion 124.

[0072] The operation of the fuel cell stack 10 constructed as described above will be briefly described below. Figure 2 and Figure 3 As shown, when the fuel cell stack 10 generates electricity, the fuel gas is supplied to the fuel gas inlet passage 42a, the oxidant gas is supplied to the oxidant gas inlet passage 38a, and the coolant is supplied to the coolant inlet passage 40a.

[0073] like Figure 2As shown in FIG. 1 , the oxidant gas is introduced into the oxidant gas flow path 54 from the oxidant gas inlet passage 38a. The oxidant gas introduced into the oxidant gas flow path 54 is supplied to the cathode electrode 36 of the MEA 24 with a resin frame while moving along the oxidant gas flow path 54 in the direction of the arrow symbol B. Figure 3 As shown, the fuel gas is introduced from the fuel gas inlet passage 42a into the fuel gas flow path 58. The fuel gas introduced into the fuel gas flow path 58 is supplied to the anode electrode 34 of the resin framed MEA 24 while moving in the direction of arrow B along the fuel gas flow path 58.

[0074] Therefore, if Figure 2 As shown, in each resin-framed MEA 24, the oxidant gas and the fuel gas are consumed by electrochemical reactions in the cathode electrode catalyst layer and the anode electrode catalyst layer, thereby generating electric power.

[0075] The oxidant gas (oxidant exhaust) that is not consumed in the electrochemical reaction flows from the oxidant gas flow path 54 into the oxidant gas outlet passage 38b. The oxidant exhaust that flows into the oxidant gas outlet passage 38b flows in the direction of arrow symbol A in the oxidant gas outlet passage 38b and is discharged from the fuel cell stack 10. Similarly, the fuel gas (fuel exhaust) that is not consumed in the electrochemical reaction flows from the fuel gas flow path 58 into the fuel gas outlet passage 42b. The fuel exhaust that flows into the fuel gas outlet passage 42b flows in the direction of arrow symbol A in the fuel gas outlet passage 42b and is discharged from the fuel cell stack 10.

[0076] The cooling medium is introduced into the cooling medium flow path 60 from the cooling medium inlet communication hole 40a. The cooling medium introduced into the cooling medium flow path 60 exchanges heat with the MEA 24 with a resin frame while moving along the cooling medium flow path 60 in the direction of the arrow symbol B. The cooling medium after the heat exchange flows into the cooling medium outlet communication hole 40b. The cooling medium flowing into the cooling medium outlet communication hole 40b flows in the cooling medium outlet communication hole 40b in the direction of the arrow symbol A and is discharged from the fuel cell stack 10.

[0077] A vehicle (not shown) equipped with the fuel cell stack 10 can be driven by the power obtained by the fuel cell stack 10 as described above. When the vehicle is running, for example, the vehicle may hit a slope. In addition, when the vehicle is running, for example, the vehicle may ride on the shoulder of the road. In these cases, the external load applied to the fuel cell stack 10 from the vehicle is likely to increase.

[0078] In the fuel cell stack 10 according to the present embodiment, the concavo-convex shape 88 is provided on the bottom plate 78 of the stack shell 16. Therefore, the overall thickness of the bottom plate 78 can be kept from increasing (suppressing the increase in the weight of the stack shell 16) and the rigidity of the stack shell 16 can be improved. Since the rigidity of the stack shell 16 is improved, even when the above-mentioned external load is applied to the fuel cell stack 10, the deformation of the stack shell 16 can be effectively suppressed. Therefore, the deformation of the single cell stack 14 accommodated in the stack shell 16 can be suppressed. As a result, the single cell stack 14 can be effectively protected from the influence of the external load.

[0079] In the fuel cell stack 10 involved in the above-mentioned embodiment, the bottom plate 78 has: a bottom plate inner surface 84, which faces the single cell stack 14; and a bottom plate outer surface 86, which is the back side of the bottom plate inner surface 84, and the direction orthogonal to the thickness direction of the bottom plate 78 and the stacking direction of the single cell stack 14 is set as the width direction, and the concave-convex shape 88 has a convex portion 90, which is arranged on the bottom plate inner surface 84 of the bottom plate 78 and protrudes toward the single cell stack 14, and the convex portion 90 is a protrusion extending along the stacking direction at the center of the width direction of the bottom plate 78.

[0080] For example, such a convex portion 90 can be disposed using a space formed inside the stack case 16. Therefore, for example, compared with a case where the convex portion 90 is provided on the bottom plate outer surface 86 and protrudes outward from the stack case 16, an increase in the outer dimensions of the stack case 16 can be easily suppressed.

[0081] In addition, by setting the protrusion 90 as a ridge extending in the stacking direction at the center of the width direction of the bottom plate 78 as described above, the stack shell 16 can be effectively suppressed from deforming in a direction intersecting the stacking direction. Furthermore, the positional displacement of the power generation cells 12 arranged in the stacking direction in the single cell stack 14 can be effectively suppressed. As a result, the sealing between the power generation cells 12 can be well maintained. As a result, the single cell stack 14 can be further well protected from external loads. Moreover, the protrusion 90 may be composed of a plurality of protrusions arranged at intervals in the stacking direction, instead of the protrusion 90 being a ridge extending continuously in the stacking direction.

[0082] In the fuel cell stack 10 according to the above embodiment, the back side of the protrusion 90 is provided on the bottom plate outer surface 86 and is sunken toward the cell stack 14. In this case, the thickness of the bottom plate 78 can be suppressed from increasing by an amount corresponding to the bottom plate outer surface 86 of the protrusion 90 sunk toward the cell stack 14. Therefore, the weight increase of the stack casing 16 can be further effectively suppressed.

[0083] In the fuel cell stack 10 according to the above embodiment, the thickness T1 of the central portion of the bottom plate 78 in the width direction is greater than the thickness T2 of the two ends of the bottom plate 78 in the width direction. In this case, it is possible to achieve a good balance between high rigidity and light weight of the stack casing 16. In addition, the bottom plate 78 may have the same thickness as a whole. Alternatively, the thickness T1 of the central portion of the bottom plate 78 in the width direction may be smaller than the thickness T2 of the two ends of the bottom plate 78 in the width direction.

[0084] In the fuel cell stack 10 involved in the above-mentioned embodiment, a pair of end panels 22a, 22b are arranged at both ends of the single cell stack 14 in the stacking direction, and a bottom support rod 94 is arranged between the upper end surface 90a of the protrusion 90 and the single cell stack 14. The support rod extends along the stacking direction between the pair of end panels 22a, 22b. The bottom support rod 94 bears the weight of the single cell stack 14 and abuts against the upper end surface 90a of the protrusion 90.

[0085] In this case, for example, even if an external load is applied to the cell stack 14 in the direction of gravity, the bottom support rod 94 can suppress deformation of the cell stack 14. Also, for example, even if an external load is applied to the cell stack 14 in the direction of gravity, the bottom support rod 94 is in contact with the upper end surface 90a of the convex portion 90, so that deformation of the bottom support rod 94 can be suppressed. Thus, the cell stack 14 accommodated in the stack case 16 can be further effectively protected from the external load.

[0086] In the fuel cell stack 10 involved in the above-mentioned embodiment, a bottom protrusion 62 is provided on the outer edge portion of each partition plate 26, and the bottom protrusion protrudes toward the bottom support rod 94. A bottom protrusion insertion portion 104 is provided on the bottom support rod 94, and the bottom protrusion insertion portion is for inserting the bottom protrusion 62 and is concave in shape. The two ends of the bottom protrusion 62 in the width direction abut against the inner wall surface 106 of the bottom protrusion insertion portion 104.

[0087] In this case, the two ends of the bottom protrusion 62 in the width direction abut against the inner wall surface 106 of the bottom protrusion insertion portion 104, so that the separator 26 of each power generation unit cell 12 can be suppressed from being displaced in the width direction. Therefore, even when an external load is applied to the fuel cell stack 10, the sealing between the inside and the outside of the single cell stack 14 can be well maintained. As a result, the single cell stack 14 accommodated in the stack case 16 can be further effectively protected from the influence of the external load.

[0088] Furthermore, a gap may be formed between the inner wall surface 106 of the bottom tab insertion portion 104 and both ends of the bottom tab 62 in the width direction when no external load in the width direction is applied to the cell stack 14. In this case, when an external load in the width direction is applied to the cell stack 14 and the bottom tab 62 moves relative to the bottom tab insertion portion 104 in the width direction, the inner wall surface 106 of the bottom tab insertion portion 104 abuts against one end of the bottom tab 62 in the width direction. This can suppress positional displacement of the separator 26 of each power generation cell 12 in the width direction.

[0089] In the fuel cell stack 10 according to the above-mentioned embodiment, the bottom tab insertion portion 104 is formed by a base portion 108 and a group of rising portions 110, the base portion 108 having an upper surface 112 facing the lower end surface 62a of the bottom tab 62 inserted into the bottom tab insertion portion 104 with a gap, the group of rising portions 110 being arranged to sandwich the bottom tab 62 in the width direction and protrude from the base portion 108 toward the cell stack 14, the rising portions 110 having inner wall surfaces 106 abutting against both ends of the bottom tab 62 in the width direction and abutting surfaces 114 abutting against the cell stack 14, and the bottom support rod 94 receiving the self-weight of the cell stack 14 via the abutting surfaces 114. In this case, it is possible to avoid the situation where the bottom tab 62 is deformed by receiving at least one of the self-weight of the cell stack 14 and the external load in the gravity direction. Therefore, the durability of the fuel cell stack 10 can be improved.

[0090] In the fuel cell stack 10 involved in the above-mentioned embodiment, a pair of end panels 22a, 22b constitute a part of the stack shell 16. In this case, the rigidity of the stack shell 16 can be improved by the concavo-convex shape 88 of the bottom plate 78. Therefore, even when an external load is applied to the fuel cell stack 10, the positional displacement of the end panels 22a, 22b relative to the single cell stack 14 can be suppressed. Therefore, a state in which a tightening load is applied to the single cell stack 14 via the end panels 22a, 22b can be well maintained. In addition, a situation in which, for example, the single cell stack 14 is twisted can be effectively suppressed. Furthermore, a state in which the inside and the outside of the single cell stack 14 are well sealed can be easily maintained.

[0091] Furthermore, the pair of end panels 22a and 22b may not constitute the stack case 16. In this case, for example, the stack case 16 may be configured to surround the outer sides of the pair of end panels 22a and 22b.

[0092] In the fuel cell stack 10 involved in the above-mentioned embodiment, the concave-convex shape 88 includes a concave portion 92, which is arranged on both sides of the bottom plate 78 in the width direction of the convex portion 90, and the partition plate 26 has a protrusion 68, which protrudes toward the concave portion 92, and the bottom surface 92a of the concave portion 92 on the inner surface 84 of the bottom plate and the lower end surface 68a of the protrusion 68 are maintained in a state where a gap is formed between each other.

[0093] In this case, for example, regardless of whether the outer edge of each separator 26 of the single cell stack 14 is subjected to insulation treatment, the single cell stack 14 and the stack shell 16 can be maintained in an electrically insulated state. In particular, in the fuel cell stack 10, as described above, the rigidity of the stack shell 16 is improved, and deformation is suppressed. Therefore, a state in which a gap is formed between the bottom surface 92a of the bottom plate inner surface 84 of the recess 92 and the lower end surface 68a of the protrusion 68 can be well maintained. As a result, the structure and manufacturing process of the fuel cell stack 10 can be simplified.

[0094] Furthermore, the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

Claims

1. A fuel cell stack, comprising: a single cell stack (14) having a plurality of power generation cells (12) formed by stacking a plurality of the power generation cells, wherein the power generation cells are formed by sandwiching an electrolyte membrane-electrode structure (28) between a separator (26); and a stack casing (16) accommodating the single cell stack, wherein in the fuel cell stack (10), The bottom plate (78) of the stack housing has a concave-convex shape (88), The bottom plate has: a bottom plate inner surface (84) facing the single cell stack; and a bottom plate outer surface (86) which is the back side of the bottom plate inner surface, and the bottom plate has a width direction perpendicular to both the thickness direction of the bottom plate and the stacking direction of the single cell stack. The concavo-convex shape has a convex portion (90) which is provided on the inner surface of the bottom plate of the bottom plate and protrudes toward the single cell stack. A pair of end panels (22a, 22b) are provided at both ends of the single cell stack in the stacking direction. A bottom support rod (94) is provided between the upper end surface (90a) of the convex portion and the single cell stack, and the bottom support rod extends between the pair of end panels along the stacking direction. A bottom protrusion (62) is provided on the outer edge of each of the partitions, and the bottom protrusion protrudes toward the bottom support rod. A bottom protrusion inserting portion (104) is provided on the bottom support rod, and the bottom protrusion is inserted into the bottom protrusion and is concave in shape. The bottom protrusion inserting portion comprises: a base portion (108), the base portion having a facing surface (112), the facing surface facing the lower end surface of the bottom protrusion inserted into the bottom protrusion inserting portion at a distance in the thickness direction of the bottom plate; a group of rising portions (110), the group of rising portions protruding from both sides of the base in the width direction toward the single cell stack; as well as a contact surface (114) provided on the set of rising portions and contacting the single cell stack; The weight of the single cell stack is input to the bottom support bar via the contact surface of the bottom tab insertion portion. Both ends of the bottom protrusion in the width direction abut against the inner wall surface (106) of the bottom protrusion insertion portion, The lower end surface of the bottom support rod abuts against the upper end surface of the convex portion.

2. The fuel cell stack according to claim 1, characterized in that: The rear side of the convex portion is provided on the outer surface of the bottom plate and is sunken toward the cell stack.

3. The fuel cell stack according to claim 1, characterized in that: The thickness of the bottom plate in the center portion in the width direction is greater than the thickness of both ends of the bottom plate in the width direction.

4. The fuel cell stack according to claim 1, characterized in that: The pair of end panels form a portion of the stack housing.

5. The fuel cell stack according to any one of claims 1 to 4, characterized in that: The concavo-convex shape includes a concave portion (92), the concave portion being arranged on both sides of the bottom plate in the width direction sandwiching the convex portion. The partition plate has a protrusion (68) protruding toward the recessed portion. The bottom surface (92a) of the recessed portion on the inner surface of the bottom plate and the lower end surface of the protruding portion are maintained in a state where a gap is formed between them.

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