Fuel cell stack

Abstract

A fuel cell stack (1) capable of discharging air from a cooling medium flow path without causing an increase in size, and in which power generation cells (2) each having an electrolyte membrane / electrode structure (20) and a set of separators (21, 22) positioned on both sides of the electrolyte membrane / electrode structure, respectively, are stacked in a first direction extending in a horizontal direction, the fuel cell stack characterized in that a cooling medium flow path (58) is formed between the separators of each set, a cooling medium inlet communication hole (32) and a cooling medium outlet communication hole (35) extending through the power generation cells in the first direction and connected with the cooling medium flow path are formed, and an upper end portion of the cooling medium outlet communication hole extends further upward than an upper end portion of the cooling medium flow path.

Description

Technical Field

[0001] This invention relates to a fuel cell stack. Background Technology

[0002] In recent years, efforts to achieve a low-carbon or carbon-neutral society have become increasingly active, and in the vehicle sector, research and development related to electrification technologies have been conducted to reduce CO2 emissions and improve energy efficiency. In particular, fuel cells have attracted significant attention as a sustainable energy source with minimal environmental impact because they do not emit CO2.

[0003] Patent Document 1 discloses a fuel cell stack in which power generation cells are stacked horizontally, each cell including an electrolyte membrane-electrode assembly and a pair of partitions disposed on both sides of the electrolyte membrane-electrode assembly. Cooling medium flow paths are formed between adjacent partitions. Each cooling medium flow path extends horizontally, with one end connected to a cooling medium inlet communication hole and the other end connected to a cooling medium outlet communication hole. Furthermore, the upper part of each cooling medium flow path is connected to an air release communication hole. Thus, air that has entered the cooling medium flow path and accumulated in the upper part of the cooling medium flow path is discharged to the outside of the fuel cell stack through the air release communication hole.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: JP4081428B2 Summary of the Invention

[0007] The task to be accomplished by this invention

[0008] However, when the power generation cell has an air release connection hole, there is a problem of reduced space for providing the power generation area and for the fluid holes for distributing cooling media or reactant gases. Furthermore, there is a problem that ensuring space for the power generation area and fluid holes may increase the overall size of the fuel cell stack.

[0009] In view of the foregoing background, the object of the present invention is to provide a fuel cell stack capable of discharging air from the cooling medium flow path without increasing its size. Furthermore, the object of the present invention is to improve energy efficiency in order to reduce the size of the fuel cell stack.

[0010] means of completing the task

[0011] To achieve the above objectives, one aspect of the present invention provides a fuel cell stack 1, wherein power generation cells 2, each having an electrolyte membrane-electrode assembly 20 and a pair of separators 21, 22 disposed on corresponding sides of the electrolyte membrane-electrode assembly, are stacked along a first direction extending horizontally, wherein a cooling medium flow path 58 is formed between each pair of separators, and a cooling medium inlet communication hole 32 and a cooling medium outlet communication hole 35 are formed extending along the first direction through the power generation cells and connected to the cooling medium flow path, and the upper end of the cooling medium outlet communication hole extends further upward than the upper end of each cooling medium flow path.

[0012] According to this aspect, since the upper end of the cooling medium outlet connecting hole extends further upward than the upper end of each cooling medium flow path, air that has entered the cooling medium flow path can easily flow to the cooling medium outlet connecting hole. Therefore, air in the cooling medium flow path can be efficiently discharged to the outside through the cooling medium outlet connecting hole. Since no dedicated air discharge path is provided except for the cooling medium outlet connecting hole, the size of the fuel cell stack can be reduced. Based on the foregoing, a fuel cell stack capable of discharging air from the cooling medium flow path without increasing its size can be provided.

[0013] In the above aspects, each cooling medium flow path may extend in the horizontal direction along a second direction perpendicular to the first direction, the cooling medium inlet communication hole may be provided on one side of the cooling medium flow path in the second direction, and the cooling medium outlet communication hole may be provided on the other side of the cooling medium flow path in the second direction.

[0014] According to this aspect, the cooling medium flows horizontally from the cooling medium inlet connecting hole to the cooling medium outlet connecting hole through the cooling medium flow path, so air is unlikely to remain in the cooling medium flow path.

[0015] In the above respects, the upper end of each cooling medium flow path may extend in a horizontal direction.

[0016] Based on this, it is unlikely that air will remain in the cooling medium flow path.

[0017] In the above aspects, each of the two separators can form a reactive gas flow path 42, 52 between itself and the electrolyte membrane-electrode assembly, and can form a reactive gas inlet communication hole 31, 34 and a reactive gas outlet communication hole 33, 35 extending through the power generation cell in the first direction and connected to the reactive gas flow path. The cooling medium outlet communication hole can extend in the vertical direction, and the reactive gas inlet communication hole can be disposed in the second direction between the cooling medium outlet communication hole and the cooling medium flow path.

[0018] Based on this, both the reactant gas inlet connection hole and the cooling medium outlet connection hole can be located in the upper part of the power generation cell. Since the reactant gas inlet connection hole is located in the upper part of the power generation cell, the reactant gas can also be appropriately supplied to the upper part of the power generation cell.

[0019] In the above respect, an air discharge passage 66 is formed between each pair of partitions, the air discharge passage passing above the reaction gas inlet communication hole and connecting the upper end of the cooling medium flow path and the cooling medium outlet communication hole.

[0020] According to this aspect, air in each cooling medium flow path can flow through the air exhaust passage to the cooling medium outlet connection hole without being blocked by the reaction gas inlet connection hole.

[0021] In the above aspects, when viewed along the first direction, each power generation cell can be formed as a rectangle extending in the second direction, and the reaction gas inlet connection hole and the reaction gas outlet connection hole can be located at opposite corners of the power generation cell.

[0022] According to this aspect, the reactive gas can flow from the reactive gas inlet connection hole to the reactive gas outlet connection hole along the diagonal direction of each power generation cell, thereby the reactive gas can be efficiently supplied to each part of the power generation cell.

[0023] In the above aspects, the reaction gas inlet communication hole may include an oxidant gas inlet communication hole for oxidant gas to flow through and a fuel gas inlet communication hole for fuel gas to flow through, and the fuel gas inlet communication hole may be arranged adjacent to the cooling medium outlet communication hole.

[0024] Based on this, condensation of the oxidant gas in the oxidant gas inlet connection hole can be suppressed. The fuel gas is typically hydrogen and is unlikely to condense. Therefore, even if the fuel gas inlet connection hole and the cooling medium outlet connection hole are arranged adjacent to each other, condensation is unlikely to occur in the fuel gas inlet connection hole.

[0025] In the above aspects, the cooling medium inlet connecting hole can be located below the oxidant gas inlet connecting hole, and the distance between the cooling medium inlet connecting hole and the oxidant gas inlet connecting hole can be greater than the distance between the cooling medium outlet connecting hole and the fuel gas inlet connecting hole.

[0026] Based on this, the condensation of oxidant gas in the oxidant gas inlet connecting hole can be suppressed.

[0027] Invention Effects

[0028] Based on the aforementioned configuration, a fuel cell stack capable of discharging air from the cooling medium flow path without increasing its size can be provided. Attached Figure Description

[0029] Figure 1 : A 3D view of a fuel cell stack.

[0030] Figure 2 : Exploded 3D diagram of a power generation cell

[0031] Figure 3 This diagram shows a cross-section of the power generation cells in the stacking direction.

[0032] Figure 4 Plan view of the first surface side of the first partition.

[0033] Figure 5 Plan view of the first surface side of the second partition. Detailed Implementation

[0034] In the following description, embodiments of the fuel cell stack 1 will be illustrated with reference to the accompanying drawings. The fuel cell stack 1 can be installed in a vehicle such as an electric vehicle, or it can be used as a stationary type.

[0035] like Figure 1 As shown, the fuel cell stack 1 includes a plurality of power-generating cells 2 stacked along a first direction, and a first end plate 3 and a second end plate 4 sandwiching the plurality of power-generating cells 2 along the first direction. A first terminal plate 6 and a first insulator 7 are inserted between the first end plate 3 and the power-generating cells 2. Furthermore, a second terminal plate 8 and a second insulator 9 are inserted between the second end plate 4 and the power-generating cells 2. The first insulator 7 and the second insulator 9 are made of insulating materials such as polycarbonate and phenolic resin.

[0036] The first end plate 3 and the second end plate 4 are joined together by a plurality of connecting rods 11 extending along a first direction. Each connecting rod 11 applies a fastening load to a plurality of power generation cells 2 in the first direction.

[0037] The first direction extends horizontally. A direction perpendicular to the first direction in the horizontal plane is defined as the second direction. A direction perpendicular to both the first and second directions is defined as the third direction. The first direction can be called the stacking direction, the second direction can be called the width direction, and the third direction can be called the height direction or the vertical direction.

[0038] like Figure 2As shown, each power generation cell 2 includes an electrolyte membrane-electrode assembly 20 and a first separator 21 and a second separator 22 disposed on both sides of the electrolyte membrane-electrode assembly 20. A resin frame member 23 is disposed on the outer periphery of the electrolyte membrane-electrode assembly 20. The electrolyte membrane-electrode assembly 20 and the resin frame member 23 constitute a resin frame MEA 24.

[0039] like Figure 3 As shown, the electrolyte membrane-electrode assembly 20 includes an electrolyte membrane 26, an anode electrode 27 disposed on one surface of the electrolyte membrane 26, and a cathode electrode 28 disposed on the other surface of the electrolyte membrane 26. The electrolyte membrane 26 is, for example, a solid polymer electrolyte membrane (cation exchange membrane), such as a thin film made of perfluorosulfonic acid containing water. The electrolyte membrane 26 is sandwiched between the anode electrode 27 and the cathode electrode 28. The electrolyte membrane 26 can be a fluorine-based electrolyte or a hydrocarbon-based electrolyte.

[0040] The anode electrode 27 includes an anode catalyst layer bonded to one surface of the electrolyte membrane 26 and an anode gas diffusion layer disposed on the anode catalyst layer. The cathode electrode 28 includes a cathode catalyst layer bonded to the other surface of the electrolyte membrane 26 and a cathode gas diffusion layer disposed on the cathode catalyst layer.

[0041] For example, an anode electrode catalyst layer is formed by uniformly applying porous carbon particles, on which platinum alloy is supported, together with an ionically conductive polymer binder to the surface of an anode gas diffusion layer. Similarly, a cathode electrode catalyst layer is formed by uniformly applying porous carbon particles, on which platinum alloy is supported, together with an ionically conductive polymer binder to the surface of a cathode gas diffusion layer. Both the cathode and anode gas diffusion layers are formed from conductive porous sheets (e.g., carbon paper or carbon cloth).

[0042] like Figure 2 and Figure 3 As shown, the resin frame member 23 is formed in a frame shape. The inner peripheral edge of the resin frame member 23 is joined to the outer peripheral edge of the electrolyte membrane-electrode assembly 20.

[0043] like Figure 1 and Figure 2 As shown, when viewed along the first direction, the power generation cell 2, the first end plate 3, and the second end plate 4 are formed as rectangles extending in the second direction. At one end of the plurality of power generation cells 2, the first end plate 3, and the first insulator 7 in the second direction, an oxidant gas inlet connection hole 31, a cooling medium inlet connection hole 32, and a fuel gas outlet connection hole 33 are arranged in this order from the top. The oxidant gas inlet connection hole 31, the cooling medium inlet connection hole 32, and the fuel gas outlet connection hole 33 extend along the first direction through the plurality of power generation cells 2, the first end plate 3, and the first insulator 7.

[0044] like Figure 2 As shown, on the other end side of the plurality of power generation cells 2, the first end plate 3, and the first insulator 7 in the second direction, a fuel gas inlet connection hole 34, a cooling medium outlet connection hole 35, and an oxidant gas outlet connection hole 36 are arranged in this order from the top side. The fuel gas inlet connection hole 34, the cooling medium outlet connection hole 35, and the oxidant gas outlet connection hole 36 extend along the first direction through the plurality of power generation cells 2, the first end plate 3, and the first insulator 7.

[0045] For example, an oxygen-containing oxidant gas (such as air) is supplied to the oxidant gas inlet connection 31. The oxidant gas is discharged from the oxidant gas outlet connection 36. For example, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet connection 32. The cooling medium is discharged from the cooling medium outlet connection 35. For example, a hydrogen-containing fuel gas is supplied to the fuel gas inlet connection 34. The fuel gas is discharged from the fuel gas outlet connection 33.

[0046] The cooling medium inlet connecting hole 32, the cooling medium outlet connecting hole 35, the oxidant gas inlet connecting hole 31, the oxidant gas outlet connecting hole 36, the fuel gas inlet connecting hole 34, and the fuel gas outlet connecting hole 33 can be collectively referred to as connecting holes. The oxidant gas and the fuel gas can be collectively referred to as reactant gases. The oxidant gas inlet connecting hole 31 and the fuel gas inlet connecting hole 34 can be collectively referred to as reactant gas inlet connecting holes, and the oxidant gas outlet connecting hole 36 and the fuel gas outlet connecting hole 33 can be collectively referred to as reactant gas outlet connecting holes.

[0047] like Figure 2 As shown, both the first partition 21 and the second partition 22 are rectangular thin plates having a pair of long sides extending along a second direction and a pair of short sides extending along a third direction. Each pair of first partitions 21 and second partitions 22 adjacent to each other in the first direction are joined together at their outer peripheral portions. This joining can be achieved using fusion welding, brazing, riveting, etc.

[0048] Both the first partition 21 and the second partition 22 can be thin metal sheets, such as steel sheets, stainless steel sheets, aluminum sheets, plated steel sheets, titanium sheets, etc. The first partition 21 and the second partition 22 are pressed into a corrugated shape. The surfaces of the first partition 21 and the second partition 22 can be treated to prevent corrosion. The outer edges of the first partition 21 and the second partition 22 can be provided with an insulating resin material. Each of the first partition 21 and the second partition 22 has first surfaces 21A and 22A and second surfaces 21B and 22B, where the first surfaces 21A and 22A are surfaces facing the resin frame MEA 24, and the second surfaces 21B and 22B are surfaces opposite to the first surfaces.

[0049] like Figure 4 As shown, the first surface 21A of the first partition 21 is provided with a plurality of annular beaded edges 41A to 41G protruding toward the resin frame MEA 24. The beaded edges 41A to 41G are integrally formed on the first partition 21 by compression molding or the like. Grooves are formed on the second surface 21B side of the beaded edges 41A to 41G. Beaded edge 41A surrounds the oxidant gas inlet communication hole 31. Beaded edge 41B surrounds the cooling medium inlet communication hole 32. Beaded edge 41C surrounds the fuel gas outlet communication hole 33. Beaded edge 41D surrounds the fuel gas inlet communication hole 34. Beaded edge 41E surrounds the cooling medium outlet communication hole 35. Beaded edge 41F surrounds the oxidant gas outlet communication hole 36. Beaded edge 41G integrally surrounds beaded edges 41A, 41C, 41D, and 41F. Beaded edges 41B and 41D are disposed outside beaded edge 41G. Beaded edges 41A to 41G do not intersect each other. Furthermore, the regions surrounded by beaded edges 41A to 41F do not overlap. A portion of beaded edge 41G extends along beaded edges 41A to 41F. Beaded edges 41A to 41G are in hermetically tight contact with the resin frame MEA 24, thereby preventing leakage of oxidant gases, fuel gases, and cooling media.

[0050] The first surface 21A of the first partition 21 is provided with a plurality of beaded edges 43 forming an oxidant gas flow path 42 (reaction gas flow path). The beaded edges 43 are protrusions formed at equal intervals in the third direction (vertical direction) on the side of the resin frame MEA 24. Recesses formed between the beaded edges 43 constitute the oxidant gas flow path 42. The portion 42A of the oxidant gas flow path 42 facing the power generation section (which is the electrolyte membrane-electrode assembly 20) is generally referred to as the power generation region. The plurality of beaded edges 43 are integrally formed on the first partition 21 by compression molding or the like. The plurality of beaded edges 43 are disposed inside the beaded edges 41G. Among the multiple beaded edges 43 forming the oxidant gas flow path 42, the oxidant gas flow path inlet portion 42B, which extends from the beaded edge 41A surrounding the oxidant gas inlet connecting hole 31 to portion 42A (power generation area), and the oxidant gas flow path outlet portion 42C, which extends from portion 42A (power generation area) to the beaded edge 41F surrounding the oxidant gas outlet connecting hole 36, are referred to as the non-power generation area.

[0051] The beaded edge 41A is provided with an oxidant gas inlet channel 45 extending through the beaded edge 41A to connect the oxidant gas inlet communication hole 31 and the oxidant gas flow path inlet portion 42B. The beaded edge 41F is provided with an oxidant gas outlet channel 46 extending through the beaded edge 41F to connect the oxidant gas outlet communication hole 36 and the oxidant gas flow path outlet portion 42C. Oxidant gas flows from the oxidant gas inlet communication hole 31 through the oxidant gas inlet channel 45, the oxidant gas flow path inlet portion 42B, portion 42A, the oxidant gas flow path outlet portion 42C, and the oxidant gas outlet channel 46 to the oxidant gas outlet communication hole 36.

[0052] like Figure 5 As shown, the first surface 22A of the second partition 22 is provided with a plurality of annular beaded edges 51A to 51G protruding toward the resin frame MEA 24. The plurality of beaded edges 51A to 51G are integrally formed on the second partition 22 by compression molding or the like. Recessed portions are formed on the second surface 22B side of the plurality of beaded edges 51A to 51G. Beaded edge 51A surrounds the oxidant gas inlet communication hole 31. Beaded edge 51B surrounds the cooling medium inlet communication hole 32. Beaded edge 51C surrounds the fuel gas outlet communication hole 33. Beaded edge 51D surrounds the fuel gas inlet communication hole 34. Beaded edge 51E surrounds the cooling medium outlet communication hole 35. Beaded edge 51F surrounds the oxidant gas outlet communication hole 36. Beaded edge 51G integrally surrounds beaded edges 51A, 51C, 51D, and 51F. Beaded edges 51B and 51D are located outside beaded edge 51G. Beaded edges 51A to 51G do not intersect each other. Furthermore, the regions surrounded by beaded edges 51A to 51F do not overlap. A portion of beaded edge 51G extends along beaded edges 51A to 51F. Beaded edges 51A to 51F are in hermetically tight contact with the resin frame MEA24, thereby preventing leakage of oxidant gases, fuel gases, and cooling media.

[0053] The first surface 22A of the second partition 22 is provided with a plurality of beaded edges 53 defining a fuel gas flow path 52 (reaction gas flow path). The beaded edges 53 are protrusions formed at equal intervals in a third direction (vertical direction) and protruding toward the resin frame MEA 24. Recesses formed between the beaded edges 53 form the fuel gas flow path 52. The portion 52A of the fuel gas flow path 52 facing the power generation section (which is the electrolyte membrane-electrode assembly 20) is generally referred to as the power generation region. The plurality of beaded edges 53 are integrally formed on the second partition 22 by compression molding or the like. The plurality of beaded edges 53 are disposed inside the beaded edges 51G. The plurality of beaded edges 53 constituting the fuel gas flow path 52 extend from the beaded edge 51D surrounding the fuel gas inlet communication hole 34 to the beaded edge 51C surrounding the fuel gas outlet communication hole 33. The fuel gas flow path 52 is formed between the beaded edges 53.

[0054] like Figure 2 and Figure 5 As shown, the fuel gas flow path 52 includes a portion 52A extending in a second direction and facing the electrolyte membrane-electrode assembly 20 to form a power generation section, a fuel gas flow path inlet portion 52B extending from one end of portion 52A in the second direction to a bead edge 51D, and a fuel gas flow path outlet portion 52C extending from the other end of portion 52A in the second direction to a bead edge 51C. In portion 52A, each bead edge 53 extends in a straight or wavy shape in the second direction. In fuel gas flow path inlet portion 52B, each bead edge 43 extends straight downward from bead edge 51D toward portion 52A. In fuel gas flow path outlet portion 52C, each bead edge 53 extends straight upward toward portion 52A. Each bead edge 53 preferably contacts the resin frame MEA 24.

[0055] The beaded flange 51D is provided with a fuel gas inlet channel 55 extending through the beaded flange 51D to connect the fuel gas inlet connecting hole 34 and the fuel gas flow path inlet portion 52B. The beaded flange 51C is provided with a fuel gas outlet channel 56 extending through the beaded flange 51C to connect the fuel gas outlet connecting hole 33 and the fuel gas flow path outlet portion 52C. Fuel gas flows from the fuel gas inlet connecting hole 34 through the fuel gas inlet channel 55, the fuel gas flow path inlet portion 52B, portion 52A, the fuel gas flow path outlet portion 52C, and the fuel gas outlet channel 56 to the fuel gas outlet connecting hole 33.

[0056] like Figure 2 and Figure 3 As shown, a cooling medium flow path 58 is formed between the second surface 21B (opposite surface of 21A) of each pair of facing first partitions 21 and the second surface 22B of second partition 22. The cooling medium flow path 58 is formed by the shape of the second surface 21B of the first partition 21 and the second surface 22B of the second partition 22. Preferably, the cooling medium flow path 58 is formed between the grooved portion on the second surface 21B side of bead edge 43 and the second surface 22B of the second partition 22, between the grooved portion on the second surface 22B side of bead edge 53 and the second surface 21B of the first partition 21, and between the grooved portion on the second surface 21B side of bead edge 43 and the grooved portion on the second surface 22B side of bead edge 53. When viewed along a first direction, the grooved portions on the second surface 21B side of multiple bead edges 43 and the grooved portions on the second surface 22B side of multiple bead edges 53 overlap at multiple locations and form a continuous passage. The cooling medium flow path 58 extends along the surfaces of the first partition 21 and the second partition 22 in the second and third directions.

[0057] like Figure 4As shown, the first partition 21 or the second partition 22 is provided with a cooling medium inlet channel 61 connecting the cooling medium inlet communication hole 32 and the cooling medium flow path 58. The cooling medium inlet channel 61 communicates with the internal space of the bead rim 41B and bead rim 41G and has an opening in the wall surface of the bead rim 41B and bead rim 41G. That is, the cooling medium inlet channel 61 extends through the bead rim 41B and bead rim 41G.

[0058] The first partition 21 or the second partition 22 is provided with a cooling medium outlet channel 62 connecting the cooling medium outlet communication hole 35 and the cooling medium flow path 58. The cooling medium outlet channel 62 communicates with the internal space of the bead rim 41E and bead rim 41G and has an opening in the wall surface of the bead rim 41E and bead rim 41G. The cooling medium outlet channel 62 extends through the bead rim 41E and bead rim 41G. The cooling medium flows from the cooling medium inlet communication hole 32 through the cooling medium inlet channel 61, the cooling medium flow path 58 and the cooling medium outlet channel 62 to the cooling medium outlet communication hole 35.

[0059] The grooved portions on the second surface 21B side of bead edge 41G and the grooved portions on the second surface 22B side of bead edge 51G face each other and form an annular bypass flow path 63 along bead edge 41G and bead edge 51G. The bypass flow path 63 is connected to the cooling medium inlet channel 61 and the cooling medium outlet channel 62.

[0060] The first partition 21 or the second partition 22 is provided with a first air discharge channel 65 (first air discharge passage) connecting the upper end of the cooling medium inlet communication hole 32 and the bypass flow path 63 (the entire bead rim 41G). The first air discharge channel 65 can connect the internal spaces of the bead rim 41B and the bead rim 41G, or it can connect the internal spaces of the bead rim 51B and the bead rim 51G. The connection portion of the first air discharge channel 65 and the bypass flow path 63 is preferably configured to be higher than the connection portion of the first air discharge channel 65 and the cooling medium inlet communication hole 32. Moreover, the connection portion of the first air discharge channel 65 and the bypass flow path 63 is preferably configured to be higher than the connection portion of the uppermost cooling medium inlet channel 61 and the bypass flow path 63.

[0061] The first partition 21 or the second partition 22 is provided with a second air discharge channel 66 (second air discharge passage) connecting the upper end of the cooling medium outlet communication hole 35 and the upper end of the bypass flow path 63. The second air discharge channel 66 may extend through the bead rim 41E and bead rim 41G, or it may extend through the bead rim 51E and bead rim 51G. The connection portion between the second air discharge channel 66 and the bypass flow path 63 is preferably positioned above the upper end of the electrolyte membrane-electrode assembly 20. Moreover, the connection portion between the second air discharge channel 66 and the cooling medium outlet communication hole 35 is preferably positioned above the upper end of the electrolyte membrane-electrode assembly 20.

[0062] Air trapped in the upper part of the cooling medium inlet connecting hole 32 passes through the first air discharge passage 65, the bypass flow path 63, and the second air discharge passage 66, and is discharged into the cooling medium outlet connecting hole 35. As a result, it becomes less likely for air to enter the cooling medium flow path 58.

[0063] like Figure 3 As shown, sealing member 68 is disposed between each bead edge 41A to 41G of the first partition 21 and the resin frame member 23. Furthermore, sealing member 69 is disposed between each bead edge 51A to 51G of the second partition 22 and the resin frame member 23. Sealing members 68 and 69 press against the resin frame member 23 to prevent leakage of oxidant gas, fuel gas, or cooling medium.

[0064] like Figure 2 , Figure 4 and Figure 5 As shown, on one end of the power generation cell 2 in the second direction, the oxidant gas inlet connection hole 31, the cooling medium inlet connection hole 32, and the fuel gas outlet connection hole 33 are arranged in a downward staggered sequence. On the other end of the power generation cell 2 in the second direction, the fuel gas inlet connection hole 34, the cooling medium outlet connection hole 35, and the oxidant gas outlet connection hole 36 are arranged in the same downward staggered sequence.

[0065] When viewed along the first direction, the oxidant gas inlet connection hole 31 and the oxidant gas outlet connection hole 36 are located diagonally opposite each power generation cell 2. Furthermore, when viewed along the first direction, the fuel gas inlet connection hole 34 and the fuel gas outlet connection hole 33 are located diagonally opposite each power generation cell 2. Thus, oxidant gas flows from the oxidant gas inlet connection hole 31 to the oxidant gas outlet connection hole 36 along the diagonal direction of the power generation cell 2. Similarly, fuel gas flows from the fuel gas inlet connection hole 34 to the fuel gas outlet connection hole 33 along the diagonal direction of the power generation cell 2. Therefore, oxidant gas and fuel gas can be efficiently supplied to each part of the power generation cell 2.

[0066] The fuel gas inlet connection hole 34 and the oxidant gas outlet connection hole 36 are positioned closer to the center of each power generation cell 2 in the second direction than the cooling medium outlet connection hole 35. The oxidant gas inlet connection hole 31 and the fuel gas outlet connection hole 33 are positioned closer to the center of each power generation cell 2 in the second direction than the cooling medium inlet connection hole 32.

[0067] The end of each of the oxidizer gas inlet connecting hole 31 and the fuel gas outlet connecting hole 33 on the central side in the second direction is positioned closer to the center in the second direction than the end of the cooling medium inlet connecting hole 32 on the central side in the second direction. The end of the cooling medium inlet connecting hole 32 on the central side in the second direction is positioned closer to the center in the second direction than the end of each of the oxidizer gas inlet connecting hole 31 and the fuel gas outlet connecting hole 33 on one end side in the second direction.

[0068] The end of each of the fuel gas inlet connecting hole 34 and the oxidant gas outlet connecting hole 36 on the central side in the second direction is configured to be closer to the center in the second direction than the end of the cooling medium outlet connecting hole 35 on the central side in the second direction.

[0069] The distance between the oxidizer gas inlet connecting hole 31 and the cooling medium inlet connecting hole 32 is greater than the distance between the cooling medium inlet connecting hole 32 and the fuel gas outlet connecting hole 33. A gap is provided between the oxidizer gas inlet connecting hole 31 and the cooling medium inlet connecting hole 32 in a third-order upward direction. The lower end of the cooling medium inlet connecting hole 32 is lower than the upper end of the fuel gas outlet connecting hole 33.

[0070] The distance between the oxidant gas outlet connecting hole 36 and the cooling medium outlet connecting hole 35 is greater than the distance between the cooling medium outlet connecting hole 35 and the fuel gas inlet connecting hole 34. A gap is provided between the oxidant gas outlet connecting hole 36 and the cooling medium outlet connecting hole 35 in the third direction.

[0071] The fuel gas inlet connection hole 34 and the cooling medium outlet connection hole 35 are arranged adjacent to each other. The distance between the oxidant gas inlet connection hole 31 and the cooling medium inlet connection hole 32 is greater than the distance between the cooling medium outlet connection hole 35 and the fuel gas inlet connection hole 34. This suppresses condensation of the oxidant gas in the oxidant gas inlet connection hole. The fuel gas is hydrogen and is unlikely to condense. Therefore, even though the fuel gas inlet connection hole 34 and the cooling medium outlet connection hole 35 are arranged adjacent to each other, condensation is unlikely to occur in the fuel gas inlet connection hole 34.

[0072] The upper end of the cooling medium outlet connecting hole 35 is located at the same height as or higher than the upper end of the fuel gas inlet connecting hole 34. The cooling medium outlet connecting hole 35 extends upward and passes to the side of the fuel gas inlet connecting hole 34 in a second direction.

[0073] Both the cooling medium inlet connecting hole 32 and the cooling medium outlet connecting hole 35 extend in a third direction. In the third direction, the width of the cooling medium inlet connecting hole 32 is greater than the width of both the oxidant gas inlet connecting hole 31 and the fuel gas outlet connecting hole 33. In the third direction, the width of the cooling medium outlet connecting hole 35 is greater than the width of both the oxidant gas outlet connecting hole 36 and the fuel gas inlet connecting hole 34.

[0074] When viewed along the first direction, the oxidant gas inlet connection hole 31 and the oxidant gas outlet connection hole 36 are located diagonally opposite each power generation cell 2. When viewed along the first direction, the fuel gas inlet connection hole 34 and the fuel gas outlet connection hole 33 are located diagonally opposite each power generation cell 2.

[0075] The upper end of the cooling medium outlet connecting hole 35 extends further upward than the upper end of each cooling medium flow path 58. The upper end of each cooling medium flow path 58 extends horizontally. The upper end of each cooling medium flow path 58 is formed by the contact portion of the first partition 21 and the second partition 22. The contact portion of the first partition 21 and the second partition 22 can be joined by welding. The upper end of each cooling medium flow path 58 extends linearly in a second direction above the electrolyte membrane-electrode assembly 20. The upper end of the cooling medium outlet connecting hole 35 extends further upward than the portion of the upper end of each cooling medium flow path 58 located above the electrolyte membrane-electrode assembly 20.

[0076] When viewed along the first direction, the upper end of the electrolyte membrane-electrode assembly 20 extends in a straight line parallel to the second direction. The upper end of the cooling medium outlet connecting hole 35 is positioned higher than the upper end of the electrolyte membrane-electrode assembly 20.

[0077] like Figure 1 As shown, attached to the first end plate 3 are an oxidant gas supply pipe 71 connected to the oxidant gas inlet communication hole 31, an oxidant gas discharge pipe 72 connected to the oxidant gas outlet communication hole 36, a fuel gas supply pipe 73 connected to the fuel gas inlet communication hole 34, a fuel gas discharge pipe 74 connected to the fuel gas outlet communication hole 33, a cooling medium supply pipe 75 connected to the cooling medium inlet communication hole 32, and a cooling medium discharge pipe 76 connected to the cooling medium outlet communication hole 35.

[0078] The oxidizer gas supply pipe 71, oxidizer gas discharge pipe 72, fuel gas supply pipe 73, fuel gas discharge pipe 74, cooling medium supply pipe 75, and cooling medium discharge pipe 76 have flanges 71A to 76A fastened to the first end plate 3. The oxidizer gas supply pipe 71, oxidizer gas discharge pipe 72, fuel gas supply pipe 73, fuel gas discharge pipe 74, cooling medium supply pipe 75, and cooling medium discharge pipe 76 are preferably formed of resin material. Adjacent flanges among 71A to 76A may be integrally formed.

[0079] A first power output terminal 78, connected to the first terminal block 6, protrudes outward from the central portion of the first terminal block 3. A second power output terminal 79, connected to the second terminal block 8, protrudes outward from the central portion of the second terminal block 4.

[0080] The operation of the fuel cell stack 1 will be described below. Oxidant gas flows through oxidant gas supply pipe 71 and oxidant gas inlet connection hole 31, and is supplied to the oxidant gas flow path 42 of each power generation cell 2. Fuel gas flows through fuel gas supply pipe 73 and fuel gas inlet connection hole 34, and is supplied to the fuel gas flow path 52 of each power generation cell 2. Cooling medium flows through cooling medium supply pipe 75 and cooling medium inlet connection hole 32, and is supplied to the cooling medium flow path 58 of each power generation cell 2.

[0081] In each electrolyte membrane-electrode assembly 20, the oxidant gas supplied to the cathode electrode 28 and the fuel gas supplied to the anode electrode 27 are consumed by an electrochemical reaction in the electrode catalyst layer, thereby generating electricity.

[0082] A portion of the oxidant gas consumed at the cathode electrode 28 of the electrolyte membrane-electrode assembly 20 and the vapor generated at the cathode electrode 28 pass through the oxidant gas outlet connection hole 36 and the oxidant gas discharge pipe 72 and are discharged to the outside of the fuel cell stack 1. A portion of the fuel gas consumed at the anode electrode 27 of the electrolyte membrane-electrode assembly 20 passes through the fuel gas outlet connection hole 33 and the fuel gas discharge pipe 74 and is discharged to the outside of the fuel cell stack 1.

[0083] Cooling medium is supplied to multiple cooling medium flow paths 58 via cooling medium supply pipe 75 and cooling medium inlet connection hole 32, and cools each power generation cell 2. Cooling medium flows from multiple cooling medium flow paths 58 through cooling medium outlet connection hole 35 and cooling medium discharge pipe, and is discharged to the outside of fuel cell stack 1.

[0084] According to the above configuration, since the upper end of the cooling medium outlet connection hole 35 extends further upward than the upper end of each cooling medium flow path 58, air entering the cooling medium flow path 58 can easily flow to the cooling medium outlet connection hole 35. Therefore, air in the cooling medium flow path 58 can be efficiently discharged to the outside through the cooling medium outlet connection hole 35. Since no dedicated air discharge path is provided other than the cooling medium outlet connection hole 35, the size of the fuel cell stack 1 can be reduced. Based on the foregoing, a fuel cell stack 1 capable of discharging air from the cooling medium flow path can be provided without increasing its size.

[0085] Since each cooling medium flow path 58 and the upper end of each cooling medium flow path 58 extend in a horizontal direction, the cooling medium flows horizontally from the cooling medium inlet communication hole 32 toward the cooling medium outlet communication hole 35 through the cooling medium flow path 58. Therefore, air is unlikely to remain in the cooling medium flow path 58.

[0086] Since a second air discharge channel 66 is formed between each pair of baffles 21, 22, extending above the fuel gas inlet connection hole 34 and connecting the upper part of the cooling medium flow path 58 and the cooling medium outlet connection hole 35, air in each cooling medium flow path 58 can flow through the second air discharge channel 66 to the cooling medium outlet connection hole 35 without being blocked by the fuel gas inlet connection hole 34.

[0087] Since the oxidant gas inlet connection hole 31, the cooling medium inlet connection hole 32, and the fuel gas outlet connection hole 33 are staggered in this order along the third direction at one end of the power generation cell 2 in the second direction, and the fuel gas inlet connection hole 34, the cooling medium outlet connection hole 35, and the oxidant gas outlet connection hole 36 are staggered in this order along the third direction at the other end of the power generation cell 2 in the second direction, the connection holes 31 to 36 can be spaced apart from each other. Therefore, each of the tubes 71 to 76 can be easily connected without increasing the size.

[0088] The specific implementation methods have been described above, but the present invention can be modified in various ways and is not limited to the above-described implementation methods.

[0089] List of reference numerals

[0090] 1: Fuel cell stack

[0091] 2: Battery cell

[0092] 20: Electrolyte membrane-electrode assembly

[0093] 21: First partition

[0094] 22: Second partition

[0095] 24: Resin Frame MEA

[0096] 31: Oxidant inlet connecting hole

[0097] 32: Cooling medium inlet connecting hole

[0098] 33: Fuel gas outlet connecting hole

[0099] 34: Fuel gas inlet connecting hole

[0100] 35: Cooling medium outlet connecting hole

[0101] 36: Oxidant gas outlet connecting hole

[0102] 41A-41G: Beaded Edge

[0103] 51A-51G: Beaded Edge

[0104] 52: Fuel gas flow path

[0105] 58: Cooling medium flow path

[0106] 63: Bypass Flow Path

[0107] 65: First air exhaust channel

[0108] 66: Second air exhaust channel

[0109] 71: Oxidant gas supply pipe

[0110] 72: Oxidizer gas emission pipe

[0111] 73: Fuel gas supply pipe

[0112] 74: Fuel gas emission pipe

[0113] 75: Cooling medium supply pipe

[0114] 76: Cooling medium discharge pipe Claims (as amended under Article 19 of the Treaty) 1. (Amended) A fuel cell stack, wherein power-generating cells, each having an electrolyte membrane-electrode assembly and a pair of separators disposed on respective sides of the electrolyte membrane-electrode assembly, are stacked along a first direction extending in a horizontal direction. A cooling medium flow path is formed between each pair of partitions. A cooling medium inlet communication hole and a cooling medium outlet communication hole are formed, which extend along the first direction through the power generation cell and are connected to the cooling medium flow path. Each cooling medium flow path extends in the horizontal direction along a second direction perpendicular to the first direction. The cooling medium inlet connecting hole is located on one side of the cooling medium flow path in the second direction. The cooling medium outlet connecting hole is located on the other side in the second direction of the cooling medium flow path. The cooling medium outlet connecting hole extends in the vertical direction, and The upper end of the cooling medium outlet connecting hole extends further upward than the upper end of each cooling medium flow path. 2. (Cancel) 3. (Modified) The fuel cell stack according to claim 1, wherein the upper end of each cooling medium flow path extends along the horizontal direction. 4. (Amended) The fuel cell stack according to claim 1, wherein each of the pairs of separators forms a reactive gas flow path between itself and the electrolyte membrane-electrode assembly. A reaction gas inlet communication hole and a reaction gas outlet communication hole are formed, extending along the first direction through the power generation cell and connected to the reaction gas flow path. The reactant gas inlet connecting hole is disposed in the second direction between the cooling medium outlet connecting hole and the cooling medium flow path. 5. The fuel cell stack according to claim 4, wherein an air discharge passage is formed between the pair of partitions, the air discharge passage passing above the reactant gas inlet communication hole and connecting the upper end of the cooling medium flow path to the cooling medium outlet communication hole. 6. The fuel cell stack according to claim 5, wherein, when viewed along the first direction, each power-generating cell is formed as a rectangle extending in the second direction, and The reactant gas inlet and outlet ports are located diagonally opposite each other in the power generation cell. 7. The fuel cell stack according to claim 4, wherein the reactant gas inlet communication port includes an oxidant gas inlet communication port for oxidant gas flow and a fuel gas inlet communication port for fuel gas flow, and The fuel gas inlet connection hole and the cooling medium outlet connection hole are arranged adjacent to each other. 8. The fuel cell stack according to claim 7, wherein the cooling medium inlet communication hole is disposed below the oxidant gas inlet communication hole, and The distance between the cooling medium inlet connecting hole and the oxidant gas inlet connecting hole is greater than the distance between the cooling medium outlet connecting hole and the fuel gas inlet connecting hole.

Claims

1. A fuel cell stack, wherein, The power-generating cells, each having an electrolyte membrane-electrode assembly and a pair of separators disposed on corresponding sides of the electrolyte membrane-electrode assembly, are stacked along a first direction, which extends in a horizontal direction. A cooling medium flow path is formed between each pair of partitions. A cooling medium inlet communication hole and a cooling medium outlet communication hole are formed, extending along the first direction through the power generation cell and connected to the cooling medium flow path. The upper end of the cooling medium outlet connecting hole extends further upward than the upper end of each cooling medium flow path.

2. The fuel cell stack according to claim 1, wherein, Each cooling medium flow path extends in the horizontal direction along a second direction perpendicular to the first direction. The cooling medium inlet connecting hole is located on one side of the cooling medium flow path in the second direction, and The cooling medium outlet connecting hole is located on the other side of the second direction of the cooling medium flow path.

3. The fuel cell stack according to claim 2, wherein, The upper end of each cooling medium flow path extends along the horizontal direction.

4. The fuel cell stack according to claim 1, wherein, Each of the separators in each pair forms a reactive gas flow path between itself and the electrolyte membrane-electrode assembly. A reaction gas inlet communication hole and a reaction gas outlet communication hole are formed, which extend along the first direction through the power generation cell and are connected to the reaction gas flow path. The cooling medium outlet connecting hole extends in the vertical direction, and The reactant gas inlet connecting hole is disposed in the second direction between the cooling medium outlet connecting hole and the cooling medium flow path.

5. The fuel cell stack according to claim 4, wherein, An air discharge passage is formed between the pair of partitions, the air discharge passage passes above the reaction gas inlet connection hole and connects the upper end of the cooling medium flow path to the cooling medium outlet connection hole.

6. The fuel cell stack according to claim 5, wherein, When viewed along the first direction, each power-generating cell is formed as a rectangle extending in the second direction, and The reactant gas inlet and outlet ports are located diagonally opposite each other in the power generation cell.

7. The fuel cell stack according to claim 4, wherein, The reaction gas inlet connection hole includes an oxidant gas inlet connection hole for oxidant gas flow and a fuel gas inlet connection hole for fuel gas flow, and The fuel gas inlet connection hole and the cooling medium outlet connection hole are arranged adjacent to each other.

8. The fuel cell stack according to claim 7, wherein, The cooling medium inlet communication hole is located below the oxidant gas inlet communication hole, and The distance between the cooling medium inlet connecting hole and the oxidant gas inlet connecting hole is greater than the distance between the cooling medium outlet connecting hole and the fuel gas inlet connecting hole.

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