fuel cell stack

Abstract

To provide a fuel cell stack which can suppress side flow of a cooling medium.SOLUTION: A fuel cell stack is formed such that membrane electrode assemblies (MEAs) and a plurality of unit cells 90 having first separators 30 and second separators 40 are laminated on each other. The first separator 30 has first protrusions 50 which come into contact with the second separator 40 of the other unit cell 90 adjacent to one of the unit cells 90. The plurality of first protrusions 50 are provided outside an outer groove passage and are aligned in a second direction Y. Each of the plurality of first protrusions 50 has: a first top wall part 51; and a pair of first side wall parts 52 located on both sides of the first top wall part 51 in the second direction Y. At least one of the pair of first side wall parts 52 is provided with a first step part 53.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a fuel cell stack. This fuel cell stack includes a plurality of stacked unit cells. Each unit cell includes two separators. Between the two separators, a membrane electrode assembly and two gas diffusion layers are provided, sandwiching the membrane electrode assembly in the stacking direction of the unit cells.

[0003] A groove-like flow path for guiding a reaction medium is provided on the surface of each separator facing the gas diffusion layer, and a groove-like flow path for forming a cavity for guiding a cooling medium between the separators of adjacent single cells is provided on the surface opposite to the facing surface of each separator.

[0004] Furthermore, the opposing surfaces of the separators are provided with convex beads and recesses formed between the beads and the flow paths. The beads are provided all around the periphery of the flow path.

[0005] The bottom walls of the recesses formed in each separator are in contact with each other (see FIG. 6A of Patent Document 1). In a fuel cell stack including such a separator, the cooling medium flowing through the cavity is prevented from flowing toward the beads, that is, from flowing by the recesses that are in contact with each other. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2020-522089 Summary of the Invention [Problem to be solved by the invention]

[0007] In such a fuel cell stack, the depth of the recesses in each separator varies. That is, relatively deep recesses and relatively shallow recesses are mixed. Therefore, gaps are likely to form between the bottom walls of the relatively shallow recesses. As a result, the cooling medium that has flowed by the side from the cavity leaks out through the gaps, reducing the effect of the recesses in suppressing the side flow. This may result in a decrease in the cooling efficiency of the cooling medium and ultimately in a decrease in the power generation efficiency of the fuel cell.

[0008] An object of the present invention is to provide a fuel cell stack that can suppress side flow of a cooling medium. [Means for solving the problem]

[0009] A fuel cell stack for achieving the above-mentioned object is a fuel cell stack formed by stacking a plurality of unit cells in a first direction, each unit cell comprising a power generation section and a first separator and a second separator sandwiching the power generation section, and a plurality of groove channels extending in a second direction and through which a cooling medium flows are arranged side by side on the surface of each of the first separator and the second separator opposite to the surface facing the power generation section, wherein the first separator has a first convex portion that protrudes toward the second separator of another unit cell adjacent to the unit cell in the first direction and is in contact with the second separator, the first convex portion is arranged outside the groove channel that is located outermost in a third direction that intersects both the first direction and the second direction, and a plurality of first convex portions are arranged side by side in the second direction, and each of the plurality of first convex portions has a top wall portion and a pair of side wall portions located on both sides of the top wall portion in the second direction, and at least one of the pair of side wall portions is provided with a step portion that has a stepped shape in the first direction.

[0010] In a fuel cell stack, multiple unit cells are clamped in a first direction. If there is variation in the length of the first protrusions in the first direction, i.e., the height of the first protrusions, some of the first protrusions will be tall and some of the first protrusions will be short.

[0011] According to the above configuration, when the first protrusions are pressed against the second separator, the step portions of the sidewalls of the relatively tall first protrusions are smoothly flexed and deformed in the first direction. This makes it difficult for gaps to form between the relatively short first protrusions and the second separator. This makes it difficult for the coolant to flow to the outside of the first protrusions through the gaps. Therefore, sideways flow of the coolant can be suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an exploded perspective view showing a unit cell of a fuel cell stack according to each embodiment of the fuel cell stack. [Figure 2] FIG. 2 is a cross-sectional view showing the fuel cell stack of the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. [Figure 4] FIG. 4 is a cross-sectional view corresponding to FIG. 3, showing a second embodiment of the fuel cell stack. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, each embodiment of a fuel cell stack will be described with reference to Figures 1 to 4. Note that in each drawing, for the sake of convenience, some of the components are shown exaggerated or simplified, and the dimensional ratios of each component may differ from the actual ratios. Furthermore, in the following description, "orthogonal" does not necessarily mean strictly orthogonal, but also includes cases where the components intersect at approximately right angles within the range in which the effects of each embodiment are achieved.

[0014] First Embodiment First, a first embodiment of a fuel cell stack will be described with reference to FIGS. As shown in FIGS. 1 and 2, the fuel cell stack is formed by stacking a plurality of unit cells 90, each of which has a rectangular plate shape as a whole.

[0015] In the following description, the stacking direction of the unit cells 90 will be referred to as a first direction X. Furthermore, among the directions perpendicular to the first direction X, the longitudinal direction of the unit cells 90 will be referred to as a second direction Y. Furthermore, the direction perpendicular to both the first direction X and the second direction Y will be referred to as a third direction Z.

[0016] The unit cell 90 has inlet-side manifolds 91, 93, and 95 for introducing a reactant gas or a cooling medium into the unit cell 90, and outlet-side manifolds 92, 94, and 96 for discharging the reactant gas and cooling medium from the unit cell 90 to the outside. In this embodiment, the inlet-side manifold 91 and the outlet-side manifold 92 are manifolds through which a fuel gas flows. The fuel gas is, for example, hydrogen gas. The inlet-side manifold 93 and the outlet-side manifold 94 are manifolds through which a cooling medium flows. The cooling medium is, for example, cooling water. The inlet-side manifold 95 and the outlet-side manifold 96 are manifolds through which an oxidizer gas flows. The oxidizer gas is, for example, air.

[0017] The inlet side manifolds 91, 93, 95 and the outlet side manifolds 92, 94, 96 are rectangular in plan view and penetrate the unit cell 90 in the first direction X. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are provided at the end of one side (the left side in the left-right direction in FIG. 1) of the unit cell 90 in the second direction Y. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are lined up in order from one side (the far side of the paper in FIG. 1) to the other side (the near side of the paper in FIG. 1) in the third direction Z.

[0018] The outlet-side manifold 92 and the inlet-side manifolds 93 and 95 are provided at the end of the unit cell 90 on the other side (the right side in FIG. 1) in the second direction Y. The outlet-side manifold 92 and the inlet-side manifolds 93 and 95 are lined up in order from the other side (the front side of the paper in FIG. 1) to one side (the back side of the paper in FIG. 1) in the third direction Z.

[0019] The unit cell 90 has a membrane electrode assembly (hereinafter referred to as MEA 10), a frame member 20 that holds the MEA 10, and a first separator 30 and a second separator 40 that sandwich the MEA 10 and the frame member 20.

[0020] Each component will be described in detail below. <mea10> 1, the MEA 10 has a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane) (not shown) and electrodes 11 and 12 provided on both sides of the electrolyte membrane. In this embodiment, the electrode bonded to one side of the electrolyte membrane in the first direction X (the upper side in the vertical direction in FIG. 1) is the cathode electrode 11. The electrode bonded to the other side of the electrolyte membrane in the first direction X (the lower side in FIG. 1) is the anode electrode 12.

[0021] Each of the electrodes 11 and 12 has a catalyst layer bonded to the electrolyte membrane and a gas diffusion layer bonded to the catalyst layer (both not shown). The MEA 10 corresponds to the power generating section of the fuel cell according to the present invention.

[0022] <Frame member 20> As shown in FIGS. 1 and 2, the frame member 20 has a rectangular frame shape that is long in the second direction Y, and is made of, for example, a synthetic resin material.

[0023] The frame member 20 has through holes 21, 22, 23, 24, 25, and 26 that form the manifolds 91, 92, 93, 94, 95, and 96, respectively. The frame member 20 has an opening 27 in the center. The MEA 10 is joined to the periphery of the opening 27 from one side in the first direction X (the upper side in FIG. 1).

[0024] <First separator 30> As shown in FIGS. 1 and 2, the first separator 30 is formed by press-forming a metal plate made of, for example, titanium or stainless steel and having a rectangular shape in plan view.

[0025] The first separator 30 has through holes 31, 32, 33, 34, 35, and 36 that form the manifolds 91, 92, 93, 94, 95, and 96, respectively. The first separator 30 has a first surface 30A having a facing surface 30a that faces the anode electrode 12 of the MEA 10 in the first direction X, and a second surface 30B having a surface 30b opposite to the facing surface 30a.

[0026] The first surface 30A is provided with a plurality of grooves 37A through which the fuel gas flows and a pair of connecting portions 37B. Note that the grooves 37A and the connecting portions 37B are shown in simplified form in FIG.

[0027] A plurality of grooves 37A are provided on the opposing surface 30a. Each of the plurality of grooves 37A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 37A is arranged at intervals in the third direction Z (see FIG. 2).

[0028] 1, the pair of connecting portions 37B extend from both sides of the plurality of groove flow paths 37A in the second direction Y toward the through holes 31, 32. Fuel gas is introduced from the inlet-side manifold 91 into the plurality of groove flow paths 37A via one connecting portion 37B. The fuel gas flowing through the plurality of groove flow paths 37A is discharged to the outlet-side manifold 92 via the other connecting portion 37B.

[0029] 1 and 2, the second surface 30B is provided with a plurality of groove channels 38A through which a coolant flows, a pair of connecting portions 38B, and a first protrusion 50. Note that the groove channels 38A and the connecting portions 38B are illustrated in a simplified form in FIG. 1. Also, the first protrusion 50 is illustrated in a simplified form in FIGS. 1 and 2.

[0030] A plurality of grooves 38A are provided on the surface 30b. Each of the plurality of grooves 38A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 38A is arranged at intervals in the third direction Z (see FIG. 2).

[0031] 2, grooves 37A are formed by the back sides of the convex portions located between adjacent grooves 38A in the third direction Z. Also, grooves 38A are formed by the back sides of the convex portions located between adjacent grooves 37A in the third direction Z.

[0032] 1 extend from both sides of the groove flow paths 38A toward the through holes 33, 34 in the second direction Y. The coolant is introduced from the inlet manifold 93 into the groove flow paths 38A via one of the connecting portions 38B. The coolant flowing through the groove flow paths 38A is discharged to the outlet manifold 94 via the other connecting portion 38B.

[0033] <First protrusion 50> 1 and 2, the first protrusions 50 are provided on the outside of a pair of outer grooves 38a that are located outermost in the third direction Z among the plurality of grooves 38A. In this embodiment, the first protrusions 50 are provided on the outside of both of the pair of outer grooves 38a (see FIG. 1). Here, "outside" in the third direction Z refers to the side that is away from the center of the unit cell 90 in the third direction Z. Note that FIG. 2 illustrates the outer grooves 38a that are located on one side of the pair of outer grooves 38a in the third direction Z (the far side of the paper in FIG. 1), and the first protrusions 50 that are located on the outside of the outer grooves 38a.

[0034] The first protrusion 50 protrudes toward the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X (see FIG. 2). The first protrusion 50 extends in the third direction Z.

[0035] 1, the first protrusions 50 are arranged at intervals in the second direction Y. The first protrusions 50 are provided over the entire range in the second direction Y where the outer groove flow passage 38a is formed.

[0036] As shown in FIG. 3, each of the plurality of first protrusions 50 has a first top wall portion 51 and a pair of first side wall portions 52 located on both sides of the first top wall portion 51 in the second direction Y. The first top wall portion 51 is in contact with the second surface 40B of the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X.

[0037] The first side wall portions 52 are provided with first step portions 53 having a stepped shape in the first direction X. In this embodiment, the first step portions 53 are provided on both of the pair of first side wall portions 52.

[0038] The first step portion 53 is located at the center of the first side wall portion 52 in the first direction X. The first side wall portion 52 has a portion (hereinafter referred to as a tip portion 52a) located closer to the first top wall portion 51 than the first step portion 53 in the first direction X, and a portion (hereinafter referred to as a base end portion 52b) located closer to the base end of the first convex portion 50 than the first step portion 53 in the first direction X.

[0039] The tip end portion 52a is located closer to the center of the first protrusion 50 in the second direction Y than the base end portion 52b. <Second separator 40> As shown in FIGS. 1 and 2, the second separator 40 is formed by press-forming a metal plate made of, for example, titanium or stainless steel and having a rectangular shape in plan view.

[0040] The second separator 40 has through holes 41, 42, 43, 44, 45, and 46 that form the manifolds 91, 92, 93, 94, 95, and 96, respectively. The second separator 40 has a first surface 40A having a facing surface 40a that faces the cathode electrode 11 of the MEA 10 in the first direction X, and a second surface 40B having a surface 40b opposite to the facing surface 40a.

[0041] The first surface 40A is provided with a plurality of grooves 47A through which the oxidant gas flows and a pair of connection portions 47B. Note that the grooves 47A and the connection portions 47B are shown in simplified form in FIG.

[0042] A plurality of grooves 47A are provided on the opposing surface 40a. Each of the plurality of grooves 47A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 47A is arranged at intervals in the third direction Z (see FIG. 2).

[0043] 1 extend from both sides of the groove flow paths 47A toward the through holes 45, 46 in the second direction Y. The oxidant gas is introduced into the groove flow paths 47A from the inlet manifold 95 via one of the connecting portions 47B. The oxidant gas flowing through the groove flow paths 47A is discharged to the outlet manifold 96 via the other connecting portion 47B.

[0044] 1 and 2, the second surface 40B is provided with a plurality of grooves 48A through which a cooling medium flows and a pair of connecting portions 48B. Note that in FIG. 1, the grooves 48A and the connecting portions 48B are illustrated in a simplified manner.

[0045] The plurality of grooves 48A are provided on the surface 40b. Each of the plurality of grooves 48A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 48A is arranged at intervals in the third direction Z (see FIG. 2).

[0046] The plurality of grooves 48A include a pair of outer grooves 48a located on the outermost sides in the third direction Z. 2, grooves 47A are formed by the back sides of the convex portions located between adjacent grooves 48A in the third direction Z. Also, grooves 48A are formed by the back sides of the convex portions located between adjacent grooves 47A in the third direction Z.

[0047] 1, the pair of connecting portions 48B extend from both sides of the plurality of groove flow paths 48A in the second direction Y toward the through holes 43, 44. The coolant is introduced into the plurality of groove flow paths 48A from the inlet-side manifold 93 via one connecting portion 48B. The coolant flowing through the plurality of groove flow paths 48A is discharged to the outlet-side manifold 94 via the other connecting portion 48B.

[0048] 2, a gasket 70 is provided outside the first protrusions 50 in the third direction Z to seal between the separator 30 of the unit cell 90 and the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X. The multiple first protrusions 50 are configured to partially fill the space S formed between the gasket 70 and the outer groove flow paths 38a, 48a in the third direction Z.

[0049] Next, the operation of the first embodiment will be described. In a fuel cell stack, a plurality of unit cells 90 are clamped together in the first direction X. Here, if there is variation in the length of the first protrusions 50 in the first direction X, i.e., the height H of the first protrusions 50 (see FIG. 3 ), tall and short first protrusions 50 will be mixed together. Therefore, the short first protrusions 50 are likely to form gaps between the unit cell 90 and the second separator 40 of another unit cell 90 adjacent to it in the first direction X.

[0050] In this regard, according to the configuration of this embodiment, when the first protrusions 50 are pressed against the second separator 40, the first step portions 53 of the first side wall portions 52 of the relatively tall first protrusions 50 among the first protrusions 50 are smoothly flexed and deformed in the first direction X. As a result, the height H of the relatively tall first protrusions 50 is reduced. Therefore, gaps are less likely to form between the relatively short first protrusions 50 and the second separator 40. This makes it less likely for the coolant to flow to the outside of the first protrusions 50 through the gaps. Therefore, sideways flow of the coolant can be suppressed.

[0051] Next, the effects of the first embodiment will be described. (1-1) The first separator 30 has a first protrusion 50 that protrudes toward the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X and contacts the second separator 40. The first protrusion 50 is provided outside the outer groove flow passage 38a that is located outermost in the third direction Z. A plurality of first protrusions 50 are provided side by side in the second direction Y. Each of the plurality of first protrusions 50 has a first top wall 51 and a pair of first side wall portions 52 located on both sides of the first top wall portion 51 in the second direction Y. The pair of first side wall portions 52 are provided with first step portions 53 that have a step shape in the first direction X.

[0052] This configuration provides the above-mentioned effects, and therefore, the side flow of the cooling medium can be suppressed. (1-2) The first protrusions 50 are provided over the entire range in the second direction Y where the outer groove flow passage 38a is formed.

[0053] With this configuration, the above-described effect is exerted over the entire range in which the outer groove passages 38a are formed in the second direction Y. Therefore, sideways flow of the cooling medium can be further suppressed.

[0054] Second Embodiment The second embodiment of the fuel cell stack will be described below, focusing on the differences from the first embodiment, with reference to Figures 1 and 4. Note that the same reference numerals are used to designate the same or corresponding components of the fuel cell stack of the second embodiment as those of the fuel cell stack of the first embodiment, and redundant explanations will be omitted.

[0055] <Second protrusion 60> As shown in FIGS. 1 and 4, the second separator 40 has a plurality of second protrusions 60 that protrude in the first direction X toward the plurality of first protrusions 50, respectively.

[0056] 1 is provided outside the pair of outer groove flow paths 48a. In this embodiment, the second protrusions 60 are provided outside both of the pair of outer groove flow paths 48a.

[0057] The second protrusion 60 extends in the third direction Z. The second protrusions 60 are arranged at intervals in the second direction Y. The second protrusions 60 are provided over the entire area in which the outer groove flow passage 48a is formed in the second direction Y. In this embodiment, one second protrusion 60 is provided at a position corresponding to each of the first protrusions 50 in the first direction X.

[0058] As shown in FIG. 4, each of the plurality of second protrusions 60 has a second top wall portion 61 and a pair of second side wall portions 62 located on both sides of the second top wall portion 61 in the second direction Y. The second top wall portion 61 is in contact with the first top wall portion 51 of the first protrusion 50 .

[0059] The second side wall portions 62 are provided with second step portions 63 having a stepped shape in the first direction X. In this embodiment, the second step portions 63 are provided on both of the pair of second side wall portions 62.

[0060] The second step portion 63 is located at the center of the second side wall portion 62 in the first direction X. The second side wall portion 62 has a portion (hereinafter referred to as a tip portion 62a) located closer to the second top wall portion 61 than the second step portion 63, and a portion (hereinafter referred to as a base end portion 62b) located closer to the base end of the second convex portion 60 in the first direction X than the second step portion 63.

[0061] The tip end 62a is located closer to the center of the second protrusion 60 in the second direction Y than the base end 62b. Next, the operation of the second embodiment will be described.

[0062] When the first convex portion 50 and the second convex portion 60 are pressed together, the first step portion 53 of the first side wall portion 52 of the first convex portion 50, which is relatively taller than the first convex portion 50, and the second step portion 63 of the second side wall portion 62 of the second convex portion 60, which is relatively taller than the second convex portion 60, smoothly flex and deform in the first direction X.

[0063] Next, the effects of the second embodiment will be described. (2-1) The second separator 40 has a plurality of second protrusions 60 that protrude toward the plurality of first protrusions 50 in the first direction X and are in contact with the plurality of first protrusions 50 .

[0064] With this configuration, the height H of the first protrusions 50 can be made lower than when the second separator 40 does not have the second protrusions 60 (see FIGS. 3 and 4). This makes it easier to form the first protrusions 50. This makes it easier to manufacture the first separator 30.

[0065] (2-2) Each of the plurality of second protrusions 60 has a second top wall portion 61 and a pair of second side wall portions 62 located on both sides of the second top wall portion 61 in the second direction Y. The pair of second side wall portions 62 are provided with second step portions 63 having a step shape in the first direction X.

[0066] This configuration achieves the above-mentioned effects, thereby suppressing the formation of a gap between the first protrusion 50 and the second protrusion 60 while suppressing the amount of flexural deformation of both the first step 53 of the first side wall 52 of the first protrusion 50 and the second step 63 of the second side wall 62 of the second protrusion 60.

[0067] (2-3) The second protrusions 60 are provided over the entire area in the second direction Y where the outer groove flow passage 48a is formed. With this configuration, the above-described effect is exerted over the entire range in which the outer groove passages 48a are formed in the second direction Y. Therefore, sideways flow of the cooling medium can be further suppressed.

[0068] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0069] The shapes of the inlet side manifolds 91, 93, 95 and the outlet side manifolds 92, 94, 96 are not limited to the rectangular shape in plan view as exemplified in the above embodiment, but may be, for example, an elliptical shape in plan view.

[0070] The flows of the reactant gas and the coolant in the manifolds 91, 92, 93, 94, 95, and 96 are not limited to those exemplified in the above embodiment. For example, the manifold 96 may be an inlet manifold for the oxidant gas, and the manifold 95 may be an outlet manifold for the oxidant gas. Accordingly, the manifold 94 may be an inlet manifold for the coolant, and the manifold 93 may be an outlet manifold for the coolant. That is, the oxidant gas flowing through the groove flow passages 47A and the coolant flowing through the groove flow passages 38A and 48A may flow in the same direction as the fuel gas flowing through the groove flow passage 37A.

[0071] The groove flow channels 37A (38A) are not limited to those extending linearly in the second direction Y as exemplified in the above embodiment. For example, the groove flow channels 37A (38A) may extend in a wavy manner in the planar direction of the opposing surface 30a (surface 30b).

[0072] The groove flow channels 47A (48A) are not limited to those extending linearly in the second direction Y as exemplified in the above embodiment. For example, the groove flow channels 47A (48A) may extend in a wavy manner in the planar direction of the opposing surface 40a (surface 40b).

[0073] The shape of the first protrusion 50 is not limited to the shape exemplified in the above embodiment. For example, a plurality of first step portions 53 may be provided for each first side wall portion 52. Furthermore, the first protrusion 50 is not limited to one in which the first step portions 53 are provided on both of the pair of first side wall portions 52, and the first step portion 53 may be provided on only one of the pair of first side wall portions 52.

[0074] The shape of the second protrusion 60 is not limited to the shape exemplified in the second embodiment. For example, a plurality of second step portions 63 may be provided for each second side wall portion 62. Furthermore, the second protrusion 60 is not limited to a configuration in which the second step portions 63 are provided on both of the pair of second side wall portions 62, and the second step portion 63 may be provided on only one of the pair of second side wall portions 62.

[0075] The second step portion 63 may be omitted from the second protrusion 60. The first protrusions 50 are not limited to being provided on the outside of both of the pair of outer groove channels 38a as illustrated in the above embodiment. The first protrusions 50 may be provided on the outside of only one of the pair of outer groove channels 38a. In this case, the second protrusions 60 are not limited to being provided on the outside of both of the pair of outer groove channels 48a, and their arrangement may be changed appropriately to match the first protrusions 50.

[0076] The fuel cell stack is not limited to the configuration in which one second protrusion 60 is provided at a position corresponding to each of the multiple first protrusions 50 in the first direction X, as illustrated in the second embodiment, and some of the second protrusions 60 may be omitted. In this case, the separator 30 includes first protrusions 50 that do not face the second protrusions 60 in the first direction X. Note that the first protrusions 50 that do not face the second protrusions 60 may be in contact with the second surface 40B of the separator 40.

[0077] The separators 30, 40 are not limited to those formed by press-forming a metal plate material, but can also be formed by, for example, cutting or etching. The material of the separators 30, 40 is not limited to titanium or stainless steel, but aluminum or carbon can also be used.

[0078] The first separator according to the present invention is not limited to the anode-side separator as exemplified in the above embodiment, but can also be used as a cathode-side separator. In this case, the second separator according to the present invention can be used as the anode-side separator. [Explanation of symbols]

[0079] H...height S…Space X…first direction Y...Second direction Z...Third direction 10...MEA 11...Cathode electrode 12...Anode electrode 20...Frame member 21...Through hole 22...Through hole 23...Through hole 24...Through hole 25...Through hole 26...Through hole 27...Opening 30...First separator 30A…First side 30a...Opposing surface 30B…Second side 30b…side 31...Through hole 32...Through hole 33...Through hole 34...Through hole 35...Through hole 36...Through hole 37A…Groove channel 37B...Connection 38A…Groove channel 38a...Outer groove channel 38B...Connection 40...Second separator 40A...Page 1 40a...opposing surface 40B…Second side 40b...side 41...Through hole 42...Through hole 43...Through hole 44...Through hole 45...Through hole 46...Through hole 47A…Groove channel 47B...Connection 48A…Groove channel 48a...Outer groove channel 48B...Connection 50...First convex part 51...First top wall part 52...first side wall portion 52a...Tip 52b...Proximal end 53...First step 60...Second convex part 61…Second top wall part 62...Second side wall portion 62a...Tip 62b...Proximal end 63...Second step 70...Gasket 90...single cell 91...Inlet manifold 92...Outlet manifold 93...Inlet manifold 94...Outlet manifold 95...Inlet manifold 96...Outlet manifold

Claims

1. A fuel cell stack is formed by stacking a plurality of unit cells in a first direction, each unit cell including a power generation section and a first separator and a second separator sandwiching the power generation section, and each of the first separator and the second separator has a surface opposite to a surface facing the power generation section, the surface of each of the first separator and the second separator having a plurality of groove channels extending in a second direction and through which a coolant flows, the first separator has a first protrusion that protrudes toward the second separator of another unit cell adjacent to the unit cell in the first direction and that contacts the second separator, the first convex portion is provided outside the groove flow path that is located outermost in a third direction that intersects both the first direction and the second direction, and a plurality of the first convex portions are provided side by side in the second direction, Each of the plurality of first protrusions has a top wall portion and a pair of side wall portions located on both sides of the top wall portion in the second direction, At least one of the pair of side wall portions is provided with a step portion having a stepped shape in the first direction, Only the top wall portion of the first convex portion is in contact with the second separator. Fuel cell stack.

2. A fuel cell stack formed by stacking a plurality of unit cells in a first direction, each unit cell comprising a power generating unit and a first separator and a second separator sandwiching the power generating unit, and each of the first separator and the second separator has a plurality of groove flow paths extending in a second direction and arranged side by side on the surface opposite to the surface facing the power generating unit, through which a cooling medium flows, the first separator has a first protrusion that protrudes toward the second separator of another unit cell adjacent to the unit cell in the first direction and that contacts the second separator, the first convex portion is provided outside the groove flow path located at the outermost position in a third direction intersecting both the first direction and the second direction, extends longer in the third direction than in the second direction, and is provided in plurality in a line in the second direction; Each of the plurality of first protrusions has a top wall portion and a pair of side wall portions located on both sides of the top wall portion in the second direction, At least one of the pair of side wall portions is provided with a step portion having a stepped shape in the first direction. Fuel cell stack.

3. the plurality of first protrusions are provided over the entire area in which the groove flow path is formed in the second direction; 3. The fuel cell stack according to claim 1 or 2.

4. the second separator has a plurality of second protrusions that protrude toward the plurality of first protrusions in the first direction and are in contact with the plurality of first protrusions; The fuel cell stack according to any one of claims 1 to 3.

5. When the top wall portion, the side wall portion, and the step portion are defined as a first top wall portion, a first side wall portion, and a first step portion, respectively, each of the second protrusions has a second top wall portion and a pair of second side wall portions located on both sides of the second top wall portion in the second direction; At least one of the pair of second side wall portions is provided with a second step portion having a step shape in the first direction. The fuel cell stack according to claim 4 .

6. the second protrusions are provided over the entire area in which the groove flow path is formed in the second direction; 6. The fuel cell stack according to claim 4 or 5.

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