Fuel cell separator and fuel cell stack

Abstract

To provide good fluid circulation in a communication passageway of a tunnel section while ensuring good sealing properties between a fluid flow path and a fluid communication hole.SOLUTION: A fluid flow channel F in a separator 10 of a fuel cell stack 16 circulates fluid, which can be either oxidant gas, fuel gas, or a cooling medium, on a separator surface direction. A portion between a fluid communication hole H that allows fluid to circulate in a stacking direction and a fluid flow channel F is sealed by a rubber seal member R. A tunnel section T intersects the rubber seal member R at an intersection 78 and communicates the fluid flow channel F and the fluid communication hole H. The rubber seal member R is made of a different material from the tunnel section T. A first portion 72 protrudes in the stacking direction from a flat portion 76, and a second portion 74 protrudes in the stacking direction from a protruding end surface Ta of the tunnel section T.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a separator for a fuel cell, which communicates between a fluid flow path and a fluid communication hole via a tunnel, and a fuel cell stack. [Background technology]

[0002] Generally, fuel cells are used in the form of a fuel cell stack, which includes a cell laminate in which a plurality of power generation cells (unit fuel cells) are stacked, and end plates or the like disposed on both ends of the cell laminate in the stacking direction. A power generation cell is constructed by sandwiching a membrane electrode assembly between a pair of separators. A compressive load (clamping load) is applied to the power generation cell in the stacking direction via the end plates or the like.

[0003] In the separators for this type of fuel cell, fluid flow paths for circulating reactant gases (oxidant gas or fuel gas) to be supplied to the membrane electrode assembly, or fluid flow paths for circulating a cooling medium used for cooling the power generation cells, etc., are formed. In the outer region arranged outside the fluid flow paths in the plane direction of the separator, fluid communication holes for individually circulating the oxidant gas, fuel gas, and cooling medium are formed penetrating in the stacking direction of the power generation cells.

[0004] For example, as disclosed in Patent Document 1, a separator is known that is provided with a bead seal portion for sealing between the fluid flow path and each fluid communication hole to prevent leakage or mixing of fluid. In this separator, for example, when an oxidant gas fluid flow path is formed, a tunnel portion is provided that intersects with the bead seal portion that seals between the fluid flow path and the oxidant gas fluid communication hole at an intersection portion. The tunnel portion communicates the oxidant gas fluid flow path and the oxidant gas fluid communication hole, making it possible to flow only the oxidant gas between them. Similarly, a bead seal portion and an intersection portion of the tunnel portion are provided between the fuel gas fluid flow path and the fuel gas fluid communication hole, and between the cooling medium fluid flow path and the cooling medium fluid communication hole, respectively.

[0005] The bead seal portion and the tunnel portion are both formed by forming a convex shape on a metallic separator by press forming or the like. In the power generation cell, the protruding end face of the bead seal portion abuts against an abutment target portion such as an adjacent electrolyte membrane electrode assembly. Therefore, when the compressive load is applied to the bead seal portion, it is pressed against the abutment target portion and elastically deforms. This ensures good sealing performance by the bead seal portion. The space formed inside the convex shape of the tunnel portion serves as a communication passage for the flow of fluid, and the corresponding fluid flow paths and fluid communication holes are connected to each other via the communication passage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-46755 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the above separator, in order to ensure good sealing between the fluid flow paths and the fluid communication holes by the bead seal portions, it is preferable that the bead seal portions are sufficiently elastically deformable under a compressive load. On the other hand, in order to allow good fluid flow between the corresponding fluid flow paths and the fluid communication holes, it is preferable that the tunnel portions are suppressed from elastically deforming even when a compressive load is applied, and the cross-sectional area of ​​the inner communication passage can be maintained sufficiently large.

[0008] However, both the bead seal portion and the tunnel portion are formed by deforming a part of the separator. Therefore, the intersection portion between the bead seal portion and the tunnel portion has an integral convex shape in which the bead seal portion and the tunnel portion are continuously formed. In such a bead seal portion, there is a concern that the rigidity is higher at the intersection portion and its vicinity than other portions that do not intersect with the tunnel portion, and that the elastic deformation is less likely to occur. As a result, there is a concern that the sealing performance between the fluid flow path and the fluid communication hole is reduced. On the other hand, there is a concern that the tunnel portion is more likely to elastically deform in a direction in which the cross-sectional area of ​​the inner communication passage is smaller at the intersection portion and its vicinity than other portions that do not intersect with the bead seal portion. As a result, there is a concern that it is difficult to circulate the fluid well in the tunnel portion.

[0009] The present invention aims to provide a separator for a fuel cell and a fuel cell stack that can ensure good sealing between the fluid flow path and the fluid communication hole, and can allow fluid to flow well through the communication passage in the tunnel portion. [Means for solving the problem]

[0010] One aspect of the present invention is a separator for a fuel cell which is stacked on a membrane electrode assembly and subjected to a compressive load in a stacking direction, the separator comprising: a fluid flow path for circulating a fluid, which is any one of an oxidant gas, a fuel gas, and a cooling medium, in a separator surface direction; a fluid communication hole which penetrates in the stacking direction an outer region arranged outside the fluid flow path in the separator surface direction and allows the fluid to flow in the stacking direction; a rubber seal member which seals between the fluid flow path and the fluid communication hole; and a hollow tunnel portion which protrudes in the stacking direction from a flat portion provided in the outer region, extends and intersects with the rubber seal member at an intersection, and forms an internal communication passage which communicates the fluid flow path and the fluid communication hole, the rubber seal member being made of a separate member from the tunnel portion, and having a first portion and a second portion which extend continuously with each other, the first portion protruding from the flat portion in the stacking direction, and the second portion protruding in the stacking direction from a protruding end face of the tunnel portion arranged at the intersection.

[0011] Another aspect of the present invention is a fuel cell stack in which a plurality of the fuel cell separators and a plurality of the membrane electrode assemblies are arranged in the stacking direction. Effect of the Invention

[0012] In this fuel cell separator, the rubber seal member that seals between the fluid flow path and the fluid communication hole, and the tunnel portion that forms the communication passage that connects the fluid flow path and the fluid communication hole are made of separate materials, and therefore, at the intersection where a compressive load is applied, the rubber seal member and the tunnel portion can be prevented from elastically deforming together, compared to when the rubber seal member and the tunnel portion are continuously formed from the same material.

[0013] That is, the rubber seal member can be sufficiently elastically deformed by the compressive load to ensure good sealing between the fluid flow path and the fluid communication hole, while the tunnel portion maintains its shape, even when a compressive load is applied, to form a communication passage with a sufficient cross-sectional area on the inside, allowing good fluid flow between the fluid flow path and the fluid communication hole.

[0014] From the above, it can be seen that the fuel cell separator of the present invention and the fuel cell stack including the separator can ensure good sealing between the fluid flow path and the fluid communication hole, and can allow fluid to flow well through the communication passage in the tunnel portion. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view of a fuel cell stack; [Diagram 2] FIG. 2 is a partial cross-sectional view taken along the line II-II in FIG. [Diagram 3] FIG. 2 is an exploded perspective view of a power generating cell. [Figure 4] FIG. 2 is a schematic front view of the MEA side of the first bipolar plate. [Diagram 5] 4 is an enlarged view of the periphery of the fuel gas inlet passage on the MEA side of the second bipolar plate. FIG. [Figure 6] 6 is a perspective explanatory view of the separator including a cross section taken along line VI-VI in FIG. 5. [Figure 7] 7A is a partial cross-sectional view taken along line VIIA-VIIA in FIG. 5, and FIG. 7B is a partial cross-sectional view taken along line VIIB-VIIB in FIG. [Figure 8] 8 is a partial cross-sectional view taken along the line VIII-VIII in FIG. 5. [Figure 9] 9A and 9B are each a partial cross-sectional view of the cell laminate taken along line II-II in FIG. 1, illustrating a rubber seal member according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A preferred embodiment of a fuel cell separator and a fuel cell stack according to the present invention will be described with reference to the accompanying drawings. In the following drawings, components having the same or similar functions and effects are designated by the same reference numerals, and repeated description may be omitted.

[0017] As shown in Figures 1 to 3, a separator 10 for a fuel cell according to this embodiment constitutes a power generation cell 12 (unit fuel cell). As shown in Figures 1 and 2, the power generation cells 12 are provided in a fuel cell stack 16 in the form of a cell stack 14 in which a plurality of cells are stacked in the horizontal direction (direction of arrow A) or in the direction of gravity (direction of arrow C). The fuel cell stack 16 can be suitably applied to, for example, a fuel cell vehicle such as a fuel cell electric vehicle (not shown), but is not particularly limited thereto and may be a stationary type or the like.

[0018] 1 and 2, a terminal plate 18a (FIG. 2), an insulator 20a, and an end plate 22a are sequentially arranged outward at one end (arrow A1 end) of the cell stack 14 in the stacking direction. A terminal plate 18b (FIG. 2), an insulator 20b, and an end plate 22b are sequentially arranged outward at the other end (arrow A2 end) of the cell stack 14 in the stacking direction.

[0019] The terminal plates 18a, 18b are made of an electrically conductive material. Examples of materials for the terminal plates 18a, 18b include metals such as copper, aluminum, and stainless steel. As shown in Fig. 1, a terminal portion 24 extending outward in the stacking direction is provided at approximately the center of each of the terminal plates 18a, 18b. The terminal portion 24 is inserted into through holes (not shown) provided in the insulators 20a, 20b and the end plates 22a, 22b, respectively, and protrudes outward in the stacking direction of the end plates 22a, 22b.

[0020] The insulators 20a, 20b are formed of an insulating material such as polycarbonate (PC) or phenol resin. Each of the insulators 20a, 20b may be composed of a plurality of sheets (for example, two sheets) stacked in the stacking direction. In this embodiment, as shown in Fig. 2, a recess is formed on the surface of each of the insulators 20a, 20b facing the cell stack 14, recessing the surface away from the cell stack 14, and the terminal plates 18a, 18b are disposed in the recess.

[0021] 1, the end plates 22a, 22b are rectangular with short sides in the direction of the arrow C and long sides in the direction of the arrow B. The end plates 22a, 22b may also be rectangular with short sides in the direction of the arrow B and long sides in the direction of the arrow C. A connecting bar 26 extending in the stacking direction (the direction of the arrow A) is disposed between the sides of the end plates 22a, 22b. Both ends of each connecting bar 26 are fixed to the inner surfaces of the end plates 22a, 22b via bolts.

[0022] As a result, a compressive load of a predetermined magnitude (hereinafter also simply referred to as "compressive load") is applied in the stacking direction to the power generation cells 12 sandwiched between the end plates 22a, 22b. Note that the fuel cell stack 16 may be configured to include a housing (not shown) with the end plates 22a, 22b as end plates, and to house the cell stack 14 in the housing.

[0023] 2 and 3, in this embodiment, each power generating cell 12 has a resin-framed MEA 28 and a pair of separators 10 that sandwich the resin-framed MEA 28. The resin-framed MEA 28 includes a membrane electrode assembly (MEA) 30 and a resin frame member 32 that surrounds the outer periphery of the membrane electrode assembly 30. As shown in Fig. 2, the membrane electrode assembly 30 has an electrolyte membrane 34, an anode electrode 36 provided on one surface (the surface on the arrow A2 side) of the electrolyte membrane 34, and a cathode electrode 38 provided on the other surface (the surface on the arrow A1 side) of the electrolyte membrane 34.

[0024] The electrolyte membrane 34 is, for example, a solid polymer electrolyte membrane (cation exchange membrane) such as a thin film of perfluorosulfonic acid containing moisture, and is sandwiched between the anode electrode 36 and the cathode electrode 38. Note that the electrolyte membrane 34 may be an HC (hydrocarbon)-based electrolyte in addition to a fluorine-based electrolyte.

[0025] The cathode electrode 38 has a cathode electrode catalyst layer 38a joined to the surface of the electrolyte membrane 34 on the arrow A1 side, and a cathode gas diffusion layer 38b laminated on the cathode electrode catalyst layer 38a. The anode electrode 36 has an anode electrode catalyst layer 36a joined to the surface of the electrolyte membrane 34 on the arrow A2 side, and an anode gas diffusion layer 36b laminated on the anode electrode catalyst layer 36a. In this embodiment, the cathode gas diffusion layer 38b and the anode gas diffusion layer 36b have planar dimensions (external dimensions) larger than those of the electrolyte membrane 34, but are not particularly limited to this.

[0026] The cathode electrode catalyst layer 38a is formed, for example, by uniformly applying porous carbon particles having a platinum alloy supported on their surfaces together with an ion-conductive polymer binder to the surface of the cathode gas diffusion layer 38b. The anode electrode catalyst layer 36a is formed, for example, by uniformly applying porous carbon particles having a platinum alloy supported on their surfaces together with an ion-conductive polymer binder to the surface of the anode gas diffusion layer 36b.

[0027] The cathode gas diffusion layer 38b and the anode gas diffusion layer 36b are formed from a conductive porous sheet such as carbon paper or carbon cloth. A conductive porous layer (not shown) may be provided between the cathode electrode catalyst layer 38a and the cathode gas diffusion layer 38b and / or between the anode electrode catalyst layer 36a and the anode gas diffusion layer 36b.

[0028] The resin frame member 32 has a frame shape, and for example, its inner peripheral edge is joined to the outer peripheral edge of the membrane electrode assembly 30. By providing the resin frame member 32 on the outer periphery of the membrane electrode assembly 30 in this manner, the area of ​​the relatively expensive electrolyte membrane 34 required to constitute one power generating cell 12 can be reduced by the amount.

[0029] The joining structure between the resin frame member 32 and the membrane electrode assembly 30 is not particularly limited, but for example, the inner peripheral edge of the resin frame member 32 may be sandwiched between the outer peripheral edge of the cathode gas diffusion layer 38b and the outer peripheral edge of the anode gas diffusion layer 36b. In this case, the inner peripheral edge face of the resin frame member 32 may be close to, abut against, or overlap the outer peripheral edge face of the electrolyte membrane 34.

[0030] Instead of the above-described joining structure, the resin frame member 32 may be configured by making the outer peripheral edge of the electrolyte membrane 34 protrude outward beyond the cathode gas diffusion layer 38b and the anode gas diffusion layer 36b, and providing frame-shaped films on both sides of the outer peripheral edge of the electrolyte membrane 34. That is, the resin frame member 32 may be configured by joining a plurality of stacked frame-shaped films with an adhesive or the like. Note that, when the electrolyte membrane 34 protrudes outward, the power generation cell 12 does not need to include the resin frame member 32.

[0031] 1, one oxidant gas inlet manifold 40a, two coolant inlet manifolds 42a, and two fuel gas outlet manifolds 44b are provided at the edges of one long side (the side indicated by arrow B1) of the power generation cell 12, the end plate 22a, and the insulators 20a, 20b. One fuel gas inlet manifold 44a, two coolant outlet manifolds 42b, and two oxidant gas outlet manifolds 40b are provided at the edges of the other long side (the side indicated by arrow B2) of the power generation cell 12, the end plate 22a, and the insulators 20a, 20b.

[0032] A fuel gas such as a hydrogen-containing gas is discharged from the fuel gas outlet manifold 44b. An oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet manifold 40a. At least one of pure water, ethylene glycol, oil, etc. is supplied as a coolant to the coolant inlet manifold 42a. A fuel gas is supplied to the fuel gas inlet manifold 44a. The coolant is discharged from the coolant outlet manifold 42b. An oxidant gas is discharged from the oxidant gas outlet manifold 40b.

[0033] The oxidant gas inlet communication hole 40a, the coolant inlet communication hole 42a, the fuel gas outlet communication hole 44b, the fuel gas inlet communication hole 44a, the coolant outlet communication hole 42b, and the oxidant gas outlet communication hole 40b (hereinafter collectively referred to as "fluid communication holes H") each penetrate the structure of the fuel cell stack 16 in the stacking direction, excluding the terminal plates 18a, 18b (Figure 2) and the end plate 22b.

[0034] The fuel gas inlet manifold 44a and the fuel gas outlet manifold 44b are also referred to collectively as the "fuel gas manifolds 44a, 44b," and the oxidant gas inlet manifold 40a and the oxidant gas outlet manifold 40b are also referred to collectively as the "oxidant gas manifolds 40a, 40b." Furthermore, the coolant inlet manifold 42a and the coolant outlet manifold 42b are also referred to collectively as the "coolant manifolds 42a, 42b."

[0035] These fluid communication holes H are arranged in a vertical arrangement (in the direction of arrows C1 and C2). Specifically, as shown in Fig. 3, at the edge portion on one end side (the side of arrow B1) in the long side direction of the power generation cell 12, two coolant inlet communication holes 42a are arranged spaced apart from each other in the vertical direction between two fuel gas outlet communication holes 44b that are arranged spaced apart from each other in the vertical direction, and the oxidant gas inlet communication hole 40a is arranged between these coolant inlet communication holes 42a.

[0036] At the edge portion on the other end side (the side indicated by arrow B2) of the power generation cell 12 in the long side direction, two cooling medium outlet communication holes 42b are arranged spaced apart in the vertical direction between two oxidant gas outlet communication holes 40b that are arranged spaced apart from each other in the vertical direction, and a fuel gas inlet communication hole 44a is arranged between these cooling medium outlet communication holes 42b.

[0037] The arrangement and number of the fluid communication holes H are not limited to the above, and can be appropriately set so as to be arranged and numbered according to the required specifications. For example, in this embodiment, two each of the fuel gas outlet communication hole 44b, the oxidant gas outlet communication hole 40b, the coolant inlet communication hole 42a, and the coolant outlet communication hole 42b are provided, but one each of them may be provided.

[0038] In this embodiment, as shown in FIG. 4 and FIG. 5, the shape of each fluid communication hole H as viewed in the stacking direction (arrow A direction) is hexagonal, but is not particularly limited thereto. For example, the shape of each fluid communication hole H as viewed in the stacking direction may be a polygonal shape other than a hexagon, or may be a rounded shape, a circular shape, or the like. In this case, it is preferable that the side of each fluid communication hole H facing the outer edge of the separator 10 as viewed in the stacking direction is a straight line along the outer edge of the separator 10. In this case, compared to a case in which the side of each fluid communication hole H is bent or curved relative to the outer edge of the separator 10, the entire side of each fluid communication hole H can be disposed close to the outer edge of the separator 10. This makes it possible to avoid the formation of an extra space between each fluid communication hole H and the outer edge of the separator 10. As a result, it becomes possible to, for example, reduce the size of the separator 10 while maintaining the area of ​​each fluid communication hole H.

[0039] As shown in Fig. 3, the separator 10 is formed by joining the outer circumferences of the stacked first bipolar plate 48 and second bipolar plate 50 together by welding, brazing, crimping, etc. Each of the first bipolar plate 48 and the second bipolar plate 50 is made of a metal material such as a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a thin plate of the metal material with a surface treatment for corrosion prevention, and is formed by pressing the cross section of the thin plate into a corrugated shape. Note that the separator 10 is not limited to being formed by joining the first bipolar plate 48 and the second bipolar plate 50, and may be formed of a single metal plate (bipolar plate).

[0040] When incorporated into the cell stack 14 as the separator 10, the first bipolar plate 48 and the second bipolar plate 50 each have an MEA side 48a, 50a facing the resin-framed MEA 28 and a refrigerant side 48b, 50b which is the reverse side of the MEA side 48a, 50a.

[0041] 4, a plurality of ridges extending linearly in the direction of arrow B are provided on the MEA side surface 48a of the first bipolar plate 48, and the oxidant gas flow passages 52 are provided in the grooves between these ridges. The ridges may be wavy. The oxidant gas flow passage 52 is fluidly connected to the one oxidant gas inlet passage 40a and the two oxidant gas outlet passages 40b via an oxidant gas tunnel 54, which will be described later. As a result, the oxidant gas flow passage 52 allows the oxidant gas to flow in the separator surface directions (the directions of arrows B and C).

[0042] As shown in Fig. 3, the MEA side surface 50a of the second bipolar plate 50 is provided with a plurality of ridges extending linearly in the direction of arrow B, and a fuel gas flow passage 56 is provided in the groove between these ridges. The ridges may be wavy. The fuel gas flow passage 56 is fluidly connected to one fuel gas inlet passage 44a and two fuel gas outlet passages 44b via a fuel gas tunnel 58, which will be described later. As a result, the fuel gas flow passage 56 allows the fuel gas to flow in the direction of the separator surface.

[0043] In the separator 10, the refrigerant side 48b of the first bipolar plate 48 and the refrigerant side 50b of the second bipolar plate 50 face each other. Between these refrigerant sides 48b, 50b, the back surface shape of the MEA side 48a of the first bipolar plate 48 and the back surface shape of the MEA side 50a of the second bipolar plate 50 overlap with each other to form a cooling medium flow field 60. The cooling medium flow field 60 is fluidly connected to each of the two cooling medium inlet passages 42a and the two cooling medium outlet passages 42b via a cooling medium tunnel 62 described later. As a result, the cooling medium flow field 60 circulates the cooling medium in the separator surface direction.

[0044] Hereinafter, the oxidant gas flow path 52, the fuel gas flow path 56, and the coolant flow path 60 will be collectively referred to as a fluid flow path F. In addition, the oxidant gas tunnel portion 54, the fuel gas tunnel portion 58, and the coolant tunnel portion 62 will be collectively referred to as a tunnel portion T.

[0045] As shown in Fig. 4, an outer region 64 is provided on the outer side of the oxidant gas flow path 52 and the coolant flow path 60 of the first bipolar plate 48 in the separator surface direction. Also, as shown in Fig. 3, an outer region 64 is provided on the outer side of the fuel gas flow path 56 and the coolant flow path 60 of the second bipolar plate 50 in the separator surface direction. When the first bipolar plate 48 and the second bipolar plate 50 form the power generating cell 12 as the separator 10, these outer regions 64 face portions that are outer than the anode electrode 36 and the cathode electrode 38 of the resin framed MEA 28 when viewed in the stacking direction.

[0046] The fluid communication holes H are provided in the outer region 64. In each separator 10, the peripheries (excluding the tunnel portions T) of the fluid communication holes H that face each other in the stacking direction of the first bipolar plate 48 and the second bipolar plate 50 are joined together by welding, brazing, or the like.

[0047] 2 and 3, the first bipolar plate 48 and the second bipolar plate 50 are each provided with a communication hole rubber seal member 66 (FIG. 3), a reactive gas rubber seal member 68, and a peripheral seal 70 (FIG. 3) that protrude in the stacking direction from the MEA side surfaces 48a, 50a toward the resin-framed MEA 28. The communication hole rubber seal member 66 and the reactive gas rubber seal member 68 are collectively referred to as rubber seal member R.

[0048] Further, the rubber seal member R provided on the first bipolar plate 48 is also referred to as the first rubber seal member R1, and the rubber seal member R provided on the second bipolar plate 50 is also referred to as the second rubber seal member R2. When the first rubber seal member R1 and the second rubber seal member R2 are not distinguished from each other, they are also collectively referred to as the rubber seal member R. In this embodiment, the first rubber seal member R1 and the second rubber seal member R2 are set to have the same or approximately the same shape and size. That is, in this embodiment, the width perpendicular to the extension direction of the first rubber seal member R1 and the width perpendicular to the extension direction of the second rubber seal member R2 are set to be the same or approximately the same.

[0049] 2, the first rubber seal member R1 and the outer peripheral seal 70 (FIG. 3) provided on the first bipolar plate 48 protrude toward the opposite side to the second bipolar plate 50 which constitutes the separator 10 together with the first bipolar plate 48. The second rubber seal member R2 and the outer peripheral seal 70 (FIG. 3) provided on the second bipolar plate 50 protrude toward the opposite side to the first bipolar plate 48 which constitutes the separator 10 together with the second bipolar plate 50.

[0050] In the separator 10 in which the first bipolar plate 48 and the second bipolar plate 50 are joined, the first rubber seal member R1 and the second rubber seal member R2 are set so as to overlap each other when viewed in the stacking direction. The outer peripheral seal 70 of the first bipolar plate 48 and the outer peripheral seal 70 of the second bipolar plate 50 are also set so as to overlap each other when viewed in the stacking direction.

[0051] For this reason, in this embodiment, the tip side in the protruding direction of the first rubber seal member R1 of the first bipolar plate 48 abuts against the tip side in the protruding direction of the second rubber seal member R2 of the second bipolar plate 50 constituting the adjacent other separator 10, with the resin frame member 32 sandwiched therebetween. The tip side in the protruding direction of the outer circumferential seal 70 (FIG. 3) of the first bipolar plate 48 also abuts against the tip side in the protruding direction of the outer circumferential seal 70 of the second bipolar plate 50 constituting the adjacent other separator 10, with the resin frame member 32 sandwiched therebetween.

[0052] 3 and 4, the rubber seal member R seals between the fluid flow passage F and the fluid communication hole H, and is made of a material having rubber elasticity. Examples of materials having rubber elasticity include various resin-based elastomers (e.g., silicone rubber and fluororubber) and vulcanized rubber. The communication hole rubber seal members 66 individually surround the periphery of each of the fluid communication holes H. The reactant gas rubber seal member 68 integrally surrounds the fluid flow passage F, the oxidant gas communication holes 40a, 40b, and the fuel gas communication holes 44a, 44b.

[0053] 2, 5 to 7A and 7B, in this embodiment, each of the communication hole rubber seal member 66 and the reaction gas rubber seal member 68 is provided as a set of two (double lips) arranged in parallel in the separator surface direction. For convenience of illustration, in Figs. 3 and 4, only one rubber seal member R is shown.

[0054] In this embodiment, the two rubber seal members R that form a pair in parallel in the separator surface direction have the same shape. As shown in Figures 7A and 7B, before the fuel cell stack 16 is assembled (when no compressive load is applied), the tip surface Ra of each rubber seal member R in the protruding direction is an arc that protrudes toward the tip side. The width of the rubber seal member R perpendicular to the extending direction decreases from the base end side toward the tip side in the protruding direction. The rubber seal member R shown in the figures other than Figures 7A and 7B is in a state where it is elastically deformed by receiving a compressive load.

[0055] The shape of the rubber seal member R is not limited to the above, and for example, the end surface Ra in the protruding direction of each rubber seal member R may be flat when no compressive load is applied. In addition, two rubber seal members R that are arranged in parallel in the separator surface direction to form a pair may have different shapes.

[0056] 4 to 7A and 7B, each of the communication hole rubber seal member 66 and the reactive gas rubber seal member 68 has a first portion 72 and a second portion 74. The first portion 72 and the second portion 74 will be described in detail later.

[0057] As shown in Fig. 3, the peripheral seal 70 goes around the outer peripheral edge of the separator 10. The peripheral seal 70 may be made of the same material having rubber elasticity as the rubber seal member R, or may be a bead seal formed by press molding or the like. When the peripheral seal 70 is made of a material having rubber elasticity, the peripheral seal 70 may be provided as a set of two parallel to the separator surface direction, as with the rubber seal member R, or as a set of three or more, or may be composed of a single seal. The peripheral seal 70 may not be provided.

[0058] As shown in Figures 4 to 7A and 7B, a flat portion 76 is provided in the outer region 64 of the separator 10. A tunnel portion T is provided in this flat portion 76. The tunnel portion T extends and intersects with the rubber seal member R at an intersection 78. Specifically, the tunnel portion T is provided in each of the flat portion 76 of the first bipolar plate 48 in Figure 4 and the flat portion 76 of the second bipolar plate 50 in Figure 5.

[0059] The tunnel portion T provided in the planar portion 76 of the first bipolar plate 48 is formed by, for example, bulging the first bipolar plate 48 integrally by press molding. The tunnel portion T provided in the planar portion 76 of the second bipolar plate 50 is formed by, for example, bulging the second bipolar plate 50 integrally by press molding. In other words, the rubber seal member R made of a material having rubber elasticity and the tunnel portion T formed from a part of the separator 10 are separate members. As shown in Figs. 6, 7B, and 8, the tunnel portion T is hollow and protrudes from the MEA side surfaces 48a, 50a of the planar portion 76 in the same direction as the protruding direction of the rubber seal member R.

[0060] In the separator 10, the tunnel portion T provided in the first bipolar plate 48 and the tunnel portion T provided in the second bipolar plate 50 are overlapped in the stacking direction. That is, the inner hollow portion of the tunnel portion T provided in the first bipolar plate 48 and the inner hollow portion of the tunnel portion T provided in the second bipolar plate 50 are in communication with each other.

[0061] 4, when viewed in the separator thickness direction (stacking direction, arrow A direction), the oxidant gas tunnel section 54 extends between the oxidant gas communication holes 40a, 40b and the fluid flow path F, and intersects with the communication hole rubber seal member 66 surrounding the oxidant gas communication holes 40a, 40b at an intersection 78. Further, a communication hole side opening 80 that opens toward the oxidant gas communication holes 40a, 40b is provided at the end of the oxidant gas tunnel section 54 on the oxidant gas communication holes 40a, 40b side in the extension direction.

[0062] Meanwhile, a flow path side opening 82 that opens toward the oxidant gas flow path 52 is provided at the end of the oxidant gas tunnel section 54 provided in the first bipolar plate 48 on the oxidant gas flow path 52 side in the extension direction. Also, the end of the oxidant gas tunnel section 54 provided in the second bipolar plate 50 on the fuel gas flow path 56 side in the extension direction is closed. Furthermore, on the coolant side 48b of the first bipolar plate 48 and the coolant side 50b of the second bipolar plate 50, the flat portions 76 around the oxidant gas tunnel section 54 are joined by welding, brazing, or the like.

[0063] As a result, a communication passage is formed inside the oxidant gas tunnel portion 54, which connects the oxidant gas communication holes 40a, 40b to the oxidant gas flow field 52. This communication passage does not connect the fluid flow fields F (the fuel gas flow field 56 and the coolant flow field 60) other than the oxidant gas flow field 52 to the oxidant gas communication holes 40a, 40b.

[0064] In this embodiment, three oxidant gas tunnels 54 are provided for each of the oxidant gas holes 40a, 40b. However, the number of oxidant gas tunnels 54 provided for each of the oxidant gas holes 40a, 40b is not particularly limited, and may be one or a number other than three.

[0065] 3 and 5, when viewed in the separator thickness direction, the fuel gas tunnel section 58 extends between the fuel gas communication holes 44a, 44b and the fluid flow path F, and intersects with the communication hole rubber seal member 66 surrounding the fuel gas communication holes 44a, 44b at an intersection 78 (FIG. 5). In addition, a communication hole side opening 80 (FIG. 5) that opens toward the fuel gas communication holes 44a, 44b is provided at the end of the fuel gas tunnel section 58 on the fuel gas communication hole 44a, 44b side in the extension direction.

[0066] Meanwhile, in the extending direction of the fuel gas tunnel section 58 provided in the second bipolar plate 50, an end portion on the fuel gas flow path 56 side is provided with a flow path side opening 82 (FIG. 5) that opens toward the fuel gas flow path 56. Also, in the extending direction of the fuel gas tunnel section 58 provided in the first bipolar plate 48, an end portion on the oxidant gas flow path 52 side is closed. Furthermore, on the coolant side 48b of the first bipolar plate 48 and the coolant side 50b of the second bipolar plate 50, the flat portions 76 around the fuel gas tunnel section 58 are joined by welding, brazing, or the like.

[0067] As a result, a communication passage is formed inside the fuel gas tunnel portion 58, connecting the fuel gas communication holes 44a, 44b to the fuel gas flow passage 56. This communication passage does not connect the fluid flow passages F (the oxidant gas flow passage 52 and the coolant flow passage 60) other than the fuel gas flow passage 56 to the fuel gas communication holes 44a, 44b.

[0068] In this embodiment, three fuel gas tunnels 58 are provided for each of the fuel gas communication holes 44a, 44b. However, the number of fuel gas tunnels 58 provided for each of the fuel gas communication holes 44a, 44b is not particularly limited, and may be one or a number other than three.

[0069] 3, when viewed in the separator thickness direction, the coolant tunnel section 62 extends between the coolant communication holes 42a, 42b and the fluid flow path F, and intersects with the communication hole rubber seal member 66 surrounding the coolant communication holes 42a, 42b and the reactive gas rubber seal member 68 at intersections 78. In addition, a communication hole side opening 80 (FIG. 4) that opens toward the coolant communication holes 42a, 42b is provided at the end of the coolant tunnel section 62 on the side of the coolant communication holes 42a, 42b in the extension direction.

[0070] On the other hand, as shown in Fig. 4, the end of the cooling medium tunnel 62 provided in the first bipolar plate 48 on the oxidant gas flow passage 52 side is closed in the extending direction. Also, the end of the cooling medium tunnel 62 provided in the second bipolar plate 50 on the fuel gas flow passage 56 side is closed in the extending direction of the cooling medium tunnel 62 provided in the second bipolar plate 50 in Fig. 3. Furthermore, the ends of the cooling medium tunnel 62 on the cooling medium flow passage 60 side on the cooling medium side 48b of the first bipolar plate 48 and the cooling medium side 50b of the second bipolar plate 50 communicate with the cooling medium flow passage 60 via a gap (not shown) formed between the cooling medium sides 48b, 50b of the first bipolar plate 48 and the second bipolar plate 50.

[0071] As a result, a communication passage is formed inside the coolant tunnel portion 62, connecting the coolant communication holes 42a, 42b to the coolant flow field 60. This communication passage does not connect the fluid flow fields F (the oxidant gas flow field 52 and the fuel gas flow field 56) other than the coolant flow field 60 to the coolant communication holes 42a, 42b.

[0072] In this embodiment, three cooling medium tunnels 62 are arranged for each cooling medium communication hole 42a, 42b. However, the number of cooling medium tunnels 62 arranged for each cooling medium communication hole 42a, 42b is not particularly limited, and may be one or a number other than three.

[0073] 6 to 8, the first portion 72 of the rubber seal member R is provided to protrude in the protruding direction from the flat portion 76. The second portion 74 of the rubber seal member R is provided to protrude in the protruding direction from the protruding end face Ta of the tunnel portion T disposed at the intersection portion 78. As shown in Figs. 6 and 8, the first portion 72 and the second portion 74 extend continuously along the extension direction of the rubber seal member R.

[0074] 7A, 7B, and 8, a protruding height H1 of the first portion 72 from the flat portion 76 and a protruding height H2 of the second portion 74 from the flat portion 76 are constant in the extension direction of the rubber seal member R. In other words, the protruding height H1 of the first portion 72 from the flat portion 76 is the same as or approximately the same as the sum of a protruding height H3 of the tunnel portion T from the flat portion 76 and a protruding height H4 of the second portion 74 from the protruding end face Ta of the tunnel portion T.

[0075] As shown in FIG. 8, at the intersection 78, the side surfaces Tb on both sides in the width direction of the tunnel portion T abut against the rubber seal member R. In this embodiment, the side surfaces Tb on both sides in the width direction of the tunnel portion T are inclined in a direction in which they approach each other as they approach the tip side in the protruding direction. Therefore, the cross-sectional shape of the tunnel portion T along the separator thickness direction is trapezoidal. Note that the side surfaces Tb on both sides in the width direction of the tunnel portion T may be aligned along the separator thickness direction. In other words, the cross-sectional shape of the tunnel portion T along the separator thickness direction may be square or rectangular. Furthermore, the side surfaces Tb on both sides in the width direction of the tunnel portion T may be curved.

[0076] Basically, the operation of the fuel cell stack 16 (FIG. 1) configured as described above will be briefly described below. As shown in FIG. 1, when generating electricity in the fuel cell stack 16, fuel gas is supplied to the fuel gas inlet passage 44a, oxidant gas is supplied to the oxidant gas inlet passage 40a, and a coolant is supplied to the coolant inlet passage 42a.

[0077] As shown in Fig. 4, the oxidant gas is introduced from the oxidant gas inlet passage 40a through a communication passage in the oxidant gas tunnel section 54 into the oxidant gas flow field 52. This oxidant gas moves along the oxidant gas flow field 52 in the direction of arrow B and is supplied to the cathode electrode 38 of the resin-framed MEA 28. Meanwhile, as shown in Fig. 5, the fuel gas is introduced from the fuel gas inlet passage 44a through a communication passage in the fuel gas tunnel section 58 into the fuel gas flow field 56. This fuel gas moves along the fuel gas flow field 56 in the direction of arrow B and is supplied to the anode electrode 36 of the resin-framed MEA 28.

[0078] Therefore, in each resin-framed MEA 28, the oxidant gas supplied to the cathode electrode 38 and the fuel gas supplied to the anode electrode 36 are consumed by electrochemical reactions in the cathode electrode catalyst layer 38a and the anode electrode catalyst layer 36a, respectively, to generate electricity.

[0079] The oxidant gas (oxidant exhaust gas) that is not consumed in the electrochemical reaction flows from the oxidant gas flow path 52 through a communication passage in the oxidant gas tunnel section 54 into the oxidant gas outlet communication hole 40b, flows through the oxidant gas outlet communication hole 40b in the direction of arrow A and is discharged from the fuel cell stack 16. Similarly, the fuel gas (fuel exhaust gas) that is not consumed in the electrochemical reaction flows from the fuel gas flow path 56 through a communication passage in the fuel gas tunnel section 58 into the fuel gas outlet communication hole 44b, flows through the fuel gas outlet communication hole 44b in the direction of arrow A and is discharged from the fuel cell stack 16.

[0080] 3, the cooling medium is introduced from the cooling medium inlet manifold 42a through a communication passage in the cooling medium tunnel 62 into the cooling medium flow path 60, and while moving along the cooling medium flow path 60 in the direction of arrow B, exchanges heat with the resin-framed MEA 28. After heat exchange, the cooling medium flows into the cooling medium outlet manifold 42b through the communication passage in the cooling medium tunnel 62, and then flows through the cooling medium outlet manifold 42b in the direction of arrow A to be discharged from the fuel cell stack 16.

[0081] As described above, in the fuel cell separator 10 according to this embodiment, the rubber seal member R that seals between the fluid flow path F and the fluid communication hole H, and the tunnel portion T that forms the communication passage that connects the fluid flow path F and the fluid communication hole H, are made of separate materials. For this reason, at the intersection 78 to which a compressive load is applied, the rubber seal member R and the tunnel portion T can be prevented from elastically deforming together, compared to when, for example, the rubber seal member R and the tunnel portion T are continuously formed from the same material.

[0082] That is, the rubber seal member R can be sufficiently elastically deformed by the compressive load to ensure good sealing between the fluid flow path F and the fluid communication hole H. On the other hand, even when a compressive load is applied to the tunnel portion T, the shape of the tunnel portion T that forms a communication passage with a sufficient cross-sectional area on the inside can be maintained, allowing good fluid flow between the fluid flow path F and the fluid communication hole H.

[0083] From the above, the separator 10 of this embodiment and the fuel cell stack 16 equipped with the separator 10 can ensure good sealing between the fluid flow path F and the fluid communication hole H, and can allow the fluid to flow well through the communication passage in the tunnel section T.

[0084] In the fuel cell separator 10 according to the above embodiment, the protruding height H1 of the first portion 72 relative to the flat surface 76 and the protruding height H2 of the second portion 74 relative to the flat surface 76 are constant in the extension direction of the rubber seal member R.

[0085] In this case, the linear pressure applied to the tip surface Ra of the rubber seal member R by the compressive load can be made uniform in the extension direction of the rubber seal member R. This makes it easier to apply an appropriate linear pressure to the entire rubber seal member R, and makes it possible to further ensure the sealing performance of the rubber seal member R. The linear pressure here is the average value per unit length in the extension direction of the rubber seal member R of the surface pressure applied to the tip surface Ra of the rubber seal member R by the compressive load.

[0086] Note that the protruding height H1 of the first portion 72 from the flat portion 76 and the protruding height H2 of the second portion 74 from the flat portion 76 may be different from each other. For example, the protruding height H2 of the second portion 74 from the flat portion 76 may be higher than the protruding height H1 of the first portion 72 from the flat portion 76.

[0087] In the fuel cell separator 10 according to the above embodiment, the rubber seal members R are provided in a set of a plurality of pieces (two pieces) arranged in parallel in the separator surface direction.

[0088] In this case, for example, in the fuel cell stack 16, even if the relative positions of the power generation cells 12 are shifted in the separator surface direction, any one of the multiple rubber seal members R can easily maintain a state in which it is arranged side by side with any one of the multiple rubber seal members R of the adjacent separator 10 in the stacking direction. This makes it possible to ensure better sealing between the fluid flow path F and the fluid communication hole H by the rubber seal member R. Also, by forming a group of multiple members, it is possible to prevent the line pressure applied to each rubber seal member R from becoming too large. This makes it possible, for example, to increase the durability of the rubber seal member R, and ultimately makes it easier to ensure sealing between the fluid flow path F and the fluid communication hole H.

[0089] In the above embodiment, an example of a rubber seal member R in which two pieces are arranged in parallel in the separator surface direction (double lip) has been described. However, the rubber seal member R may be arranged in a set of three or more pieces arranged in parallel in the separator surface direction, or may be composed of one piece (single lip) as shown in FIG. 9A.

[0090] At the intersection 78 of the separator 10 for the fuel cell according to the embodiment described above, the side surfaces Tb rising from the flat surface portion 76 on both sides in the width direction of the tunnel portion T are in contact with the rubber seal member R.

[0091] The compressive load is applied in the stacking direction, i.e., in the protruding direction of the tunnel portion T. For this reason, in the tunnel portion T to which the compressive load is applied, stress is likely to be generated in a direction in which the protruding end face Ta faces inward of the communicating passage along the stacking direction, and the side face Tb faces outward in the width direction of the communicating passage. However, since the rubber seal member R abuts against the side face Tb of the tunnel portion T, deformation of the tunnel portion T is suppressed even if the stress is generated. As a result, the cross-sectional area of ​​the communicating passage in the tunnel portion T can be maintained, and the fluid can flow smoothly through the communicating passage.

[0092] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0093] For example, in the fuel cell stack 16 according to the above embodiment, the first rubber seal member R1 and the second rubber seal member R2 are set to have the same or approximately the same shape and size, but this is not particularly limited. For example, as shown in FIG. 9B, the width of the first rubber seal member R1 is set to be larger than the width of the second rubber seal member R2. Small It may be set.

[0094] 9B shows an example in which the first rubber seal member R1 and the second rubber seal member R2, each of which is composed of one piece (single lip), have different widths. However, the first rubber seal member R1 and the second rubber seal member R2, each of which is composed of two pieces (double lip) or three or more pieces, may have different widths. Although not shown, the width of the first rubber seal member R1 may be set smaller than the width of the second rubber seal member R2.

[0095] Furthermore, for example, even if the width of the first rubber seal member R1 and the width of the second rubber seal member R2 are the same in one separator 10, the widths of the rubber seal members R may be different between separators 10 adjacent to each other in the stacking direction.

[0096] That is, in the fuel cell stack 16, the rubber sealing members R provided on each of the separators 10 stacked in the stacking direction are arranged side by side in the stacking direction, and adjacent rubber sealing members R in the stacking direction may have different widths perpendicular to the extension direction of the rubber sealing members R.

[0097] In this case, for example, in the fuel cell stack 16, even if the relative positions of the power generating cells 12 are shifted in the separator surface direction, the rubber seal members R of adjacent separators 10 can easily maintain a state in which they are in contact with each other with the resin frame member 32 sandwiched therebetween. This makes it possible to easily maintain a state in which an appropriate linear pressure is applied to the tip surface Ra of each rubber seal member R. As a result, it is possible to ensure even better sealing between the fluid flow path F and the fluid communication hole H by the rubber seal member R. [Explanation of symbols]

[0098] 10...Separator 16...Fuel cell stack 30...Electrolyte membrane / electrode structure 64...Outer area 72…First part 74…Second part 76... Plane portion 78... Intersection portion F: Fluid flow path H: Fluid communication hole H1, H2: Projection height R: Rubber seal material T: Tunnel section Ta: Protruding end surface Tb…side

Claims

1. A separator for a fuel cell that is laminated on a membrane electrode assembly and is subjected to a compressive load in a lamination direction, a fluid flow path for allowing a fluid, which is any one of an oxidant gas, a fuel gas, and a cooling medium, to flow in a direction toward a separator surface; a fluid communication hole that penetrates an outer region that is arranged outside the fluid flow path in the separator surface direction in the stacking direction and allows the fluid to flow in the stacking direction; a rubber seal member that seals between the fluid flow path and the fluid communication hole; a tunnel portion that is hollow and protrudes in the stacking direction from a flat portion provided in the outer region, extends while intersecting with the rubber seal member at an intersection portion, and forms a communication passage on an inside thereof that communicates between the fluid flow path and the fluid communication hole; Equipped with The rubber seal member is a separate member from the tunnel portion and has a first portion and a second portion that extend continuously with each other, The first portion protrudes from the planar portion in the stacking direction, The second portion protrudes in the stacking direction from a protruding end surface of the tunnel portion disposed at the intersection portion, A separator for a fuel cell, wherein the rubber sealing members consist of multiple pieces spaced apart and parallel to each other in the separator surface direction, there are gaps between the multiple rubber sealing members through which the flat surface portions are exposed, each of the multiple rubber sealing members intersects with the tunnel portion, and the tunnel portion is exposed in the gaps.

2. 2. The fuel cell separator according to claim 1, A separator for a fuel cell, wherein a protruding height of the first portion relative to the flat surface and a protruding height of the second portion relative to the flat surface are constant in an extension direction of the rubber seal member.

3. 3. The fuel cell separator according to claim 1, a separator for a fuel cell, wherein at the intersection, both side surfaces in the width direction of the tunnel portion abut against the rubber seal member.

4. 4. A fuel cell stack comprising a plurality of fuel cell separators according to claim 1 and a plurality of said membrane electrode assemblies stacked in the stacking direction.

5. 5. The fuel cell stack according to claim 4, The rubber seal members provided on the respective separators stacked in the stacking direction are arranged side by side in the stacking direction, The rubber seal members adjacent to each other in the stacking direction have different widths perpendicular to the extending direction of the rubber seal members.

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