fuel cell stack

Abstract

To provide a fuel cell stack in which side flow of cooling medium can be suppressed.SOLUTION: A fuel cell stack is formed by laminating a plurality of single cells 90 each comprising an MEA (Membrane Electrode Assembly), a first separator 30, and a second separator 40. The first separator 30 has first protruding portions 50 abutting on the second separator 40 of the other single cell 90 adjacent to the concerned single cell 90. A plurality of the first protruding portions 50 are provided outside an outside groove flow channel and arranged in a second direction Y. The second separator 40 has a plurality of second protruding portion 60 abutting on the first protruding portion 50. A second recessed portion 62 is provided at a center portion in the second direction Y, of a distal end portion 61 of each second protruding portion 60. A length L of the second recessed portion 62 is larger than a width W1 of the first protruding portion 50. A distal end portion 51 of each first protruding portion 50 is located in the second recessed portion 62.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.

[0006] Patent Document 2 also discloses a molding method for forming a separator for a fuel cell from a metal sheet. In this molding method, a continuous protrusion, i.e., a separator flow path, is formed in the metal sheet between the recess and protrusion of a fixed die and the protrusion and recess of a movable punch. The recesses of the die and punch have bottoms that are convexly curved in the center. Therefore, the center of the formed protrusion is curved concavely. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2020-522089 [Patent Document 2] Japanese Patent Application Publication No. 2018-89679 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when the molding method described in Patent Document 2, for example, is used to mold the separator for the fuel cell described in Patent Document 1, the following problem occurs. Specifically, the central portions of the opposing surfaces of the bottom walls of the recesses are curved in a concave shape. As a result, gaps are formed between the bottom walls of the recesses of each separator. As a result, the cooling medium that has flowed sideways from the cavity leaks out through the gaps, reducing the effect of the recesses in suppressing sideways flow. This may result in a decrease in the cooling efficiency of the cooling medium and, ultimately, a decrease in the power generation efficiency of the fuel cell.

[0009] It should be noted that this problem is not limited to the case where the molding method described in Patent Document 2 is applied. For example, the same problem can occur if the bottom wall of the recess has a depression due to molding shrinkage or the like.

[0010] 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]

[0011] A fuel cell stack for achieving the above object is a fuel cell stack 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, on which a plurality of groove channels extending in a second direction and through which a coolant flows are arranged side by side, wherein the first separator has a first protrusion that protrudes toward the second separator of another unit cell adjacent to the first separator in the first direction and abuts against 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 multiple first convex portions are provided side by side in the second direction, the second separator has multiple second convex portions that each protrude toward the first convex portion in the first direction and abut against the first convex portions, a recessed portion extending in the third direction is provided in the center of the tip of the second convex portion in the second direction, the length of the recessed portion in the second direction is greater than the length of the first convex portion in the second direction, and the tip of the first convex portion is located within the recessed portion.

[0012] According to this configuration, the first and second protrusions abut with the tip of the first protrusion positioned within the recess of the second protrusion. Therefore, the gap formed between the first protrusion and the recess of the second protrusion is smaller than when the length of the first protrusion in the second direction is the same as the length of the second protrusion in the second direction. This makes it difficult for the cooling medium to flow outside the first and second protrusions through the gap. Therefore, sideways flow of the cooling medium can be suppressed.

[0013] A fuel cell stack for achieving the above object 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 a plurality of groove channels extending in a second direction and through which a coolant flows are arranged side by side on a surface of each of the first separator and the second separator opposite to a surface facing the power generation section, wherein the first separator has a first protrusion that protrudes toward the second separator of another unit cell adjacent to the first unit cell in the first direction and abuts against the second separator, and the first protrusion is located outside the groove channel that is located outermost in a third direction that intersects both the first direction and the second direction. a plurality of second separators are provided, arranged side by side in the second direction, and the second separators have second convex portions that each protrude toward the first convex portion in the first direction and abut against the first convex portion, and a tip end of the first convex portion is provided with a first recessed portion that is located in a center in the second direction and extends in the third direction, and a pair of first bulges that are located on both sides of the first recessed portion in the second direction, and a tip end of the second convex portion is provided with a second recessed portion that is located in a center in the second direction and extends in the third direction, and a pair of second bulges that are located on both sides of the second recessed portion in the second direction, and only one of the pair of second bulges is located within the first recessed portion.

[0014] According to this configuration, the first and second protrusions come into contact with each other when one of the pair of second bulges of the second protrusion is located within the first recess of the first protrusion, and the other of the pair of first bulges of the first protrusion is located within the second recess of the second protrusion. Therefore, when the first and second protrusions come into contact with each other, the gap formed by the first and second recesses becomes smaller. This makes it difficult for the cooling medium to flow through the gap to the outside of the first and second protrusions. Therefore, sideways flow of the cooling medium can be suppressed. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 1 is an exploded perspective view showing a unit cell of a fuel cell stack according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the fuel cell stack of the same 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

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] <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.

[0026] 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).

[0027] <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.

[0028] 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.

[0029] 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.

[0030] 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).

[0031] 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.

[0032] 1 and 2, the second surface 30B is provided with a plurality of groove channels 38A through which a cooling medium flows, a pair of connecting portions 38B, and a first protrusion 50. Note that in FIG. 1, the groove channels 38A and the connecting portions 38B are illustrated in a simplified manner.

[0033] 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).

[0034] 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.

[0035] 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.

[0036] <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.

[0037] 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.

[0038] 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.

[0039] As shown in FIG. 3, a first recessed portion 52 and a pair of first bulged portions 53 are provided at a tip portion 51 of each first protrusion 50. The first recess 52 is located in the center of the tip 51 in the second direction Y.

[0040] As shown in FIG. 2, the first recessed portion 52 extends in the third direction Z. As shown in FIG. 3, the first recessed portion 52 is curved with respect to an imaginary line (not shown) extending in the second direction Y in a cross-sectional view.

[0041] The pair of first bulging portions 53 are located on both sides of the first recessed portion 52 in the second direction Y. In this embodiment, the height H1 of the first protrusion 50 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less.

[0042] In this embodiment, the length of the tip portion 51 in the second direction Y (hereinafter referred to as width W1) is set to 1 mm. The width W1 corresponds to the length of the first convex portion in the second direction Y according to the present invention.

[0043] In this embodiment, the depth D1 of the first recess 52 in the first direction X is set within a range of 10 μm or more and 50 μm or less. <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.

[0044] 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.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 1 and 2, the second surface 40B is provided with a plurality of groove channels 48A through which the coolant flows, a pair of connecting portions 48B, and a second protrusion 60. Note that in FIG. 1, the groove channels 48A and the connecting portions 48B are illustrated in a simplified manner.

[0049] 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).

[0050] 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.

[0051] 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.

[0052] <Second protrusion 60> 1 and 2, the second convex portions 60 are provided on the outside of a pair of outer groove channels 48a that are located outermost in the third direction Z among the plurality of groove channels 48A. In this embodiment, the second convex portions 60 are provided on the outside of both of the pair of outer groove channels 48a (see FIG. 1). Note that FIG. 2 illustrates the outer groove channel 48a that is located on one side of the pair of outer groove channels 48a in the third direction Z, and the second convex portions 60 that are located on the outside of the outer groove channel 48a.

[0053] The second protrusion 60 protrudes toward the first protrusion 50 in the first direction X (see FIG. 2). The second protrusion 60 extends in the third direction Z.

[0054] 1, the second protrusions 60 are arranged at intervals in the second direction Y. The second protrusions 60 are provided over the entire area in the second direction Y where the outer groove flow passage 48a is formed. 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.

[0055] As shown in FIG. 3, a tip end 61 of each second protrusion 60 is provided with a second recess 62 and a pair of second bulges 63. The second recess 62 is located in the center of the tip 61 in the second direction Y.

[0056] As shown in FIG. 2, the second recessed portion 62 extends in the third direction Z. As shown in FIG. 3, the second recessed portion 62 is curved with respect to an imaginary line (not shown) extending in the second direction Y in a cross-sectional view.

[0057] The pair of second bulging portions 63 are located on both sides of the second recessed portion 62 in the second direction Y. In this embodiment, the height H2 of the second protrusion 60 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less.

[0058] The length of the tip portion 61 in the second direction Y (hereinafter referred to as width W2) is greater than the width W1 of the first protrusion 50 (width W2>width W1). In this embodiment, the width W2 is set to 2 mm. In this embodiment, the depth D2 of the second recessed portion 62 in the first direction X is set within a range of 10 μm or more and 50 μm or less.

[0059] The length L of the second recess 62 in the second direction Y is greater than the width W1 of the first protrusion 50 (length L>width W1). The tip end 51 of the first protrusion 50 is located within the second recess 62 of the second protrusion 60. The pair of first bulges 53 are in contact with the second recess 62.

[0060] As shown in FIGS. 2 and 3, a gap G1 surrounded by the first recessed portion 52 and the second recessed portion 62 is formed between the first protrusion 50 and the second protrusion 60. 2, a gasket 70 is provided outside the first protrusions 50 and the second protrusions 60 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 and the multiple second protrusions 60 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.

[0061] Next, the operation of the first embodiment will be described. The first protrusion 50 and the second protrusion 60 come into contact with each other with the tip 51 of the first protrusion 50 positioned within the second recess 62 of the second protrusion 60. Therefore, the gap G1 formed by the first recess 52 of the first protrusion 50 and the second recess 62 of the second protrusion 60 is smaller than when the width W1 of the first protrusion 50 is the same as the width W2 of the second protrusion 60. This makes it difficult for the coolant to flow to the outside of the first protrusion 50 and the second protrusion 60 through the gap G1.

[0062] 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 abuts against 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. The second separator 40 has a plurality of second protrusions 60 that protrude toward the first protrusions 50 in the first direction X and abut against the first protrusions 50. A second recess 62 extending in the third direction Z is provided at the center of a tip 61 of each second protrusion 60 in the second direction Y. The length L of the second recess 62 is greater than the width W1 of the first protrusion 50. The tip 51 of the first protrusion 50 is located within the second recess 62.

[0063] This configuration provides the above-mentioned effects, and therefore, the side flow of the cooling medium can be suppressed. (1-2) The multiple first protrusions 50 are provided over the entire area in which the outer groove flow passage 38a is formed in the second direction Y. The multiple second protrusions 60 are provided over the entire area in which the outer groove flow passage 48a is formed in the second direction Y.

[0064] With this configuration, the above-described effect is exerted over the entire range in which the outer groove passages 38a, 48a are formed in the second direction Y. Therefore, sideways flow of the cooling medium can be further suppressed.

[0065] (1-3) The first separator 30 and the second separator 40 are made of metal plates. When the separators 30, 40 are made of metal plates, the recesses 52, 62 are likely to be formed at the tip ends 51, 61 of the protrusions 50, 60 during molding.

[0066] In this regard, with the above-described configuration, side flows of the cooling medium caused by the recesses 52, 62 can be suppressed. 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 Figure 4. Note that the same components of the fuel cell stack of the second embodiment as those of the fuel cell stack of the first embodiment will be assigned the same reference numerals, and redundant explanations will be omitted. Furthermore, the components of the fuel cell stack of the second embodiment that correspond to those of the fuel cell stack of the first embodiment will be assigned the reference numeral "1**", which is obtained by adding "100" to the reference numeral "**" of the first embodiment, and redundant explanations will be omitted.

[0067] <First protrusion 150> As shown in FIG. 4, a plurality of first protrusions 150 are provided on the second surface 30B of the first separator 30.

[0068] A tip end 151 of each first protrusion 150 is provided with a first recess 152 and a pair of first bulges 153A and 153B. In this embodiment, the height H3 of the first protrusion 150 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less.

[0069] The length of the tip portion 151 in the second direction Y (hereinafter referred to as width W3) is set to 2 mm in this embodiment. In this embodiment, the depth D3 of the first recessed portion 152 in the first direction X is set within a range of 10 μm or more and 50 μm or less.

[0070] <Second protrusion 160> As shown in FIG. 4, a plurality of second protrusions 160 are provided on the second surface 40B of the second separator 40.

[0071] A tip end 161 of each second protrusion 160 is provided with a second recess 162 and a pair of second bulges 163A, 163B. The second protrusion 160 has the same shape as the first protrusion 150. That is, the height H4 of the second protrusion 160 in the first direction X is the same as the height H3. Furthermore, the length of the tip 161 in the second direction Y (hereinafter referred to as width W4) is the same as the width W3. Furthermore, the depth D4 of the second recess 162 in the first direction X is the same as the depth D3.

[0072] Of the pair of second bulging portions 163A, 163B, the second bulging portion 163A located on one side in the second direction Y (the left side in the left-right direction in FIG. 4) is located within the first recessed portion 152 and abuts against the first recessed portion 152. On the other hand, of the pair of second bulging portions 163A, 163B, the second bulging portion 163B located on the other side in the second direction Y (the right side in FIG. 4) is located on the other side of the tip portion 151 of the first convex portion 150.

[0073] Furthermore, of the pair of first bulging portions 153A, 153B, the first bulging portion 153B located on the other side in the second direction Y (the right side in FIG. 4) is located within the second recessed portion 162 and abuts against the second recessed portion 162. On the other hand, of the pair of first bulging portions 153A, 153B, the first bulging portion 153A located on one side in the second direction Y (the left side in FIG. 4) is located on one side of the tip portion 161 of the second convex portion 160.

[0074] Between the first protrusion 150 and the second protrusion 160, a gap G2 surrounded by the first recess 152 and the second recess 162 is formed. Next, the operation of the second embodiment will be described.

[0075] The first protrusion 150 and the second protrusion 160 come into contact with each other in a state in which only the second bulging portion 163A of the second protrusion 160 is located within the first recessed portion 152 of the first protrusion 150 and only the pair of first bulging portions 153B of the first protrusion 150 are located within the second recessed portion 162 of the second protrusion 160. Therefore, when the first protrusion 150 and the second protrusion 160 come into contact with each other, the gap G2 formed by the first recessed portion 152 and the second recessed portion 162 becomes smaller. This makes it difficult for the coolant to flow to the outside of the first protrusion 150 and the second protrusion 160 through the gap G2.

[0076] Next, the effects of the second embodiment will be described. (2-1) The tip 151 of the first protrusion 150 is provided with a first recess 152 located in the center in the second direction Y and extending in the third direction Z, and a pair of first bulges 153A, 153B located on both sides of the first recess 152 in the second direction Y. The tip 161 of the second protrusion 160 is provided with a second recess 162 located in the center in the second direction Y and extending in the third direction Z, and a pair of second bulges 163A, 163B located on both sides of the second recess 162 in the second direction Y. Of the pair of second bulges 163A, 163B, only the second bulge 163A is located within the first recess 152.

[0077] This configuration provides the above-mentioned effects, and therefore, the side flow of the cooling medium can be suppressed. <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.

[0078] 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.

[0079] 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.

[0080] 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).

[0081] 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).

[0082] The shapes of the first protrusion 50 and the second protrusion 60 are not limited to those exemplified in the first embodiment. For example, the width W1 of the first protrusion 50 may be smaller than 1 mm or larger than 1 mm. The width W2 of the second protrusion 60 is not limited to 2 mm, and can be changed as appropriate as long as the length L of the second recess 62 is larger than the width W1. The height H1 of the first protrusion 50 may be smaller than 0.2 mm or larger than 0.8 mm. In this case, the height H2 of the second protrusion 60 is not limited to the range of 0.2 mm or more and 0.8 mm or less, and may be changed as appropriate to match the height H1 of the first protrusion 50.

[0083] The second protrusion 160 is not limited to the second protrusion 163A of the pair of second bulging portions 163A, 163B, as exemplified in the second embodiment, in which only the second protrusion 163A is located within the first recess 152. In other words, the second protrusion 160 may be any protrusion in which only one of the pair of second bulging portions 163A, 163B is located within the first recess 152.

[0084] The shapes of the first protrusion 150 and the second protrusion 160 are not limited to the shapes exemplified in the second embodiment. For example, the width W3 of the first protrusion 150 and the width W4 of the second protrusion 160 may each be smaller than 2 mm or larger than 2 mm. The shapes of the first protrusion 150 and the second protrusion 160 do not have to be identical. As long as only one of the pair of second bulges 163A, 163B is located within the first recess 152, the shapes of each can be appropriately changed. For example, the width W3 may be smaller or larger than the width W4. The height H3 may be smaller than 0.2 mm or larger than 0.8 mm. In this case, the height H4 is not limited to the range of 0.2 mm or more and 0.8 mm or less, and may be appropriately changed to match the height H3 of the first protrusion 150.

[0085] The first recessed portion 52 (152) and the second recessed portion 62 (162) are not limited to being curved relative to a virtual straight line extending in the second direction Y in a cross-sectional view, as illustrated in the above embodiment. For example, the first recessed portion 52 (152) may have a flat bottom surface extending in the planar direction of the second surface 30B. The second recessed portion 62 (162) can also be modified in a similar manner.

[0086] The first protrusion 50 is not limited to having the first recess 52 and the pair of first bulges 53, and may have, for example, a tip 51 of the first protrusion 50 having a flat shape extending in the planar direction of the second surface 30B. Even in this case, it is sufficient that the length L of the second recess 62 is greater than the width W1 of the first protrusion 50.

[0087] The first protrusions 50 (150) 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 (150) may be provided on the outside of only one of the pair of outer groove channels 38a. In this case, the second protrusions 60 (160) 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 (150).

[0088] The fuel cell stack is not limited to the configuration in which one second protrusion 60 (160) is provided at a position corresponding to each of the multiple first protrusions 50 (150) in the first direction X, as illustrated in the above embodiment, and some of the second protrusions 60 (160) may be omitted. In this case, the separator 30 includes first protrusions 50 (150) that do not face the second protrusions 60 (160) in the first direction X. Note that the first protrusions 50 (150) that do not face the second protrusions 60 (160) may be in contact with the second surface 40B of the separator 40.

[0089] The separators 30, 40 are not limited to those formed by press-forming a metal plate material, but can also be formed by cutting or etching, for example. The material of the separators 30, 40 is not limited to titanium or stainless steel, but aluminum or carbon can also be used.

[0090] 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 which case the second separator according to the present invention should be used as the anode-side separator. [Explanation of symbols]

[0091] D1, D2, D3, D4...Depth G1, G2...Gap H1, H2, H3, H4...height L...length S…Space W1, W2, W3, W4...Width X…first direction Y...Second direction Z...Third direction 10...MEA 11...Anode electrode 12...Cathode 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 50,150...First convex part 51,151...Tip 52,152...First recess 53,153A,153B...First bulge part 60,160...Second convex part 61,161...Tip 62,162...Second recess 63,163A,163B…Second bulge 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 grooves 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 abuts against 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, the second separator has a plurality of second protrusions that protrude toward the first protrusions in the first direction and abut against the first protrusions, a recessed portion extending in the third direction is provided in a central portion in the second direction of a tip end portion of the second protrusion, the recessed portion is curved with respect to an imaginary line extending in the second direction over the entirety of the second direction, a length of the recessed portion in the second direction is greater than a length of the first protrusion in the second direction; a tip end of the first protrusion is located within the recess; Fuel cell stack.

2. When the recessed portion is a second recessed portion, a first recessed portion located at a center portion in the second direction and extending in the third direction, and a pair of bulging portions located on both sides of the first recessed portion in the second direction, at a tip end of the first protrusion; The fuel cell stack of claim 1 .

3. 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 grooves 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 abuts against 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, the second separator has a plurality of second protrusions that protrude toward the first protrusions in the first direction and abut against the first protrusions, a first recessed portion located at a center of the first protrusion in the second direction and extending in the third direction, and a pair of first bulging portions located on both sides of the first recessed portion in the second direction, a second recessed portion located at a center of the second protrusion in the second direction and extending in the third direction, and a pair of second bulging portions located on both sides of the second recessed portion in the second direction, Only one of the pair of second bulging portions is located within the first recessed portion. Fuel cell stack.

4. the plurality of first convex portions and the plurality of second convex portions are provided over an entire range in which the groove flow passage is formed in the second direction; The fuel cell stack according to any one of claims 1 to 3.

5. The first separator and the second separator are made of metal plates. The fuel cell stack according to any one of claims 1 to 4.

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