JP7790199B2 - fuel cell stack - Google Patents

Description

The present invention relates to a fuel cell stack.

Patent Document 1 discloses a fuel cell stack. This fuel cell stack includes multiple stacked unit cells. Each unit cell includes two separators. Between the two separators, there is a membrane electrode assembly and two gas diffusion layers that sandwich the membrane electrode assembly in the stacking direction of the unit cells.

The surface of each separator facing the gas diffusion layer is provided with a groove-like flow path for guiding the reaction medium. The surface of each separator opposite the facing surface is provided with a groove-like flow path that forms a cavity for guiding the cooling medium between the separators of adjacent single cells.

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.

The bottom walls of the recesses formed in the separators 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.

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

Special Publication No. 2020-522089 Japanese Patent Application Laid-Open No. 2018-89679

However, when applying the molding method described in Patent Document 2, for example, to form the separators 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 effectiveness of the recesses in suppressing sideways 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.

However, this problem is not limited to applications of the molding method described in Patent Document 2. For example, it can occur in any product that has a depression in the bottom wall of the recess due to molding shrinkage or the like.

The object of the present invention is to provide a fuel cell stack that can suppress side flow of the cooling medium.

The fuel cell stack for achieving the above-mentioned objective is formed by stacking a plurality of unit cells in a first direction, each unit cell including a power generation unit and a first separator and a second separator sandwiching the power generation unit, and each of the first separator and the second separator has a plurality of groove channels extending in a second direction and through which a coolant flows, on the surface opposite to the surface facing the power generation unit, and the first separator 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. The second separator has a first convex portion, which is provided outside the groove flow path located outermost in a third direction intersecting 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 recess extending in the third direction is provided in the center of the tip of each first convex portion in the second direction, and the tip of each second convex portion is located within the recess and has a protrusion that protrudes toward the bottom surface of the recess.

With this configuration, the first and second convex portions abut with the tip of the second convex portion positioned within the recess of the first convex portion. Here, the protruding portion of the tip of the second convex portion protrudes toward the bottom surface of the recess. Therefore, compared to when a recess is provided at the tip of the second convex portion or when the tip of the second convex portion is flat, a gap is less likely to form between the recess of the first convex portion and the second convex portion. This makes it less likely for the coolant to flow outside the first and second convex portions through the gap. Therefore, sideways flow of the coolant can be suppressed.

FIG. 1 is an exploded perspective view showing a unit cell of an embodiment of a fuel cell stack. FIG. 2 is a cross-sectional view showing the fuel cell stack of the embodiment. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. FIG. 4 is a cross-sectional view showing a modified example of the fuel cell stack, which corresponds to FIG.

One embodiment of a fuel cell stack will be described below with reference to Figures 1 to 3. Note that in each drawing, some components are exaggerated or simplified for ease of explanation, and the dimensional proportions of each component may differ from the actual proportions. Furthermore, in the following description, "orthogonal" does not necessarily mean strictly perpendicular, but also includes cases where the components intersect at approximately right angles within the range that achieves the effects of each embodiment.

<Single cell 90 of fuel cell stack>
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.

In the following description, the stacking direction of the unit cells 90 will be referred to as the 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 the second direction Y. Furthermore, the direction perpendicular to both the first direction X and the second direction Y will be referred to as the third direction Z.

The unit cell 90 has inlet-side manifolds 91, 93, and 95 for introducing a reactant gas or a coolant into the unit cell 90, and outlet-side manifolds 92, 94, and 96 for discharging the reactant gas and coolant 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 coolant flows. The coolant 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.

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 an 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.

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

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 frame member 20.

Each component will be described in detail below.
<MEA10>
1 , the MEA 10 includes a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane) (not shown) and electrodes 11, 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.

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.

<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.

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 ).

<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, which has a rectangular shape in plan view.

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.

The first surface 30A is provided with a plurality of groove channels 37A through which fuel gas flows and a pair of connection portions 37B. Note that Figure 1 shows the groove channels 37A and connection portions 37B in a simplified form.

A plurality of groove channels 37A are provided on the opposing surface 30a. Each of the plurality of groove channels 37A extends linearly in the second direction Y (see Figure 1). Each of the plurality of groove channels 37A is arranged at intervals in the third direction Z (see Figure 2).

As shown in FIG. 1, a pair of connection portions 37B extend from both sides of the multiple groove flow paths 37A in the second direction Y toward each of the through holes 31 and 32. Fuel gas is introduced from the inlet manifold 91 into the multiple groove flow paths 37A via one of the connection portions 37B. Furthermore, the fuel gas flowing through the multiple groove flow paths 37A is discharged to the outlet manifold 92 via the other connection portion 37B.

As shown in Figures 1 and 2, the second surface 30B is provided with a plurality of groove channels 38A through which the cooling medium flows, a pair of connecting portions 38B, and a first protrusion 50. Note that Figure 1 shows the groove channels 38A and connecting portions 38B in a simplified form.

A plurality of groove channels 38A are provided on the surface 30b. Each of the plurality of groove channels 38A extends linearly in the second direction Y (see Figure 1). Each of the plurality of groove channels 38A is arranged at intervals in the third direction Z (see Figure 2).

As shown in FIG. 2, groove flow path 37A is formed by the backside of the convex portion located between adjacent groove flow paths 38A in the third direction Z. Also, groove flow path 38A is formed by the backside of the convex portion located between adjacent groove flow paths 37A in the third direction Z.

A pair of connection portions 38B, shown by dashed lines in FIG. 1, extend from both sides of the multiple groove flow paths 38A in the second direction Y toward each of the through holes 33, 34. The cooling medium is introduced from the inlet manifold 93 into the multiple groove flow paths 38A via one of the connection portions 38B. The cooling medium flowing through the multiple groove flow paths 38A is discharged to the outlet manifold 94 via the other connection portion 38B.

<First protrusion 50>
1 and 2, the first convex portions 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 convex portions 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 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 farthest side in the plane of FIG. 1) and the first convex portions 50 that are located on the outside of the outer grooves 38a.

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.

As shown in FIG. 1, multiple first protrusions 50 are arranged at intervals in the second direction Y. The multiple first protrusions 50 are provided over the entire area in the second direction Y where the outer groove flow path 38a is formed.

As shown in FIG. 3 , a recess 52 is provided at the tip 51 of each first protrusion 50 .
The recess 52 is located in the center of the tip 51 in the second direction Y.
As shown in FIG. 2, the recessed portion 52 extends in the third direction Z.

As shown in FIG. 3, the recessed portion 52 is curved with respect to an imaginary line (not shown) extending in the second direction Y in a cross-sectional view.
In this embodiment, the height H1 of the first convex portion 50 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less.

In this embodiment, the width W of the tip portion 51 in the second direction Y is set within a range of 0.5 mm or more and 2 mm or less.
In this embodiment, the depth D of the 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, which has a rectangular shape in plan view.

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.

The first surface 40A is provided with a plurality of groove channels 47A through which oxidant gas flows and a pair of connection portions 47B. Note that Figure 1 shows the groove channels 47A and connection portions 47B in a simplified form.

A plurality of groove channels 47A are provided on the opposing surface 40a. Each of the plurality of groove channels 47A extends linearly in the second direction Y (see Figure 1). Each of the plurality of groove channels 47A is arranged at intervals in the third direction Z (see Figure 2).

A pair of connection portions 47B, shown by dashed lines in FIG. 1, extend from both sides of the multiple groove flow paths 47A in the second direction Y toward each of the through holes 45, 46. Oxidant gas is introduced from the inlet side manifold 95 into the multiple groove flow paths 47A via one of the connection portions 47B. Furthermore, the oxidant gas flowing through the multiple groove flow paths 47A is discharged to the outlet side manifold 96 via the other connection portion 47B.

As shown in Figures 1 and 2, the second surface 40B is provided with a plurality of groove channels 48A through which the cooling medium flows, a pair of connecting portions 48B, and a second protrusion 60. Note that Figure 1 shows the groove channels 48A and connecting portions 48B in a simplified form.

A plurality of groove channels 48A are provided on the surface 40b. Each of the plurality of groove channels 48A extends linearly in the second direction Y (see Figure 1). Each of the plurality of groove channels 48A is arranged at intervals in the third direction Z (see Figure 2).

As shown in FIG. 2, groove flow path 47A is formed by the backside of the convex portion located between adjacent groove flow paths 48A in the third direction Z. Also, groove flow path 48A is formed by the backside of the convex portion located between adjacent groove flow paths 47A in the third direction Z.

As shown in FIG. 1, a pair of connection portions 48B extend from both sides of the multiple groove flow paths 48A in the second direction Y toward each of the through holes 43, 44. The cooling medium is introduced from the inlet side manifold 93 into the multiple groove flow paths 48A via one of the connection portions 48B. The cooling medium flowing through the multiple groove flow paths 48A is discharged to the outlet side manifold 94 via the other connection portion 48B.

<Second protrusion 60>
1 and 2, the second convex portions 60 are provided on the outer sides 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 outer sides 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 outer sides of the outer groove channels 48a.

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.

As shown in FIG. 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.

As shown in FIG. 3, the tip 61 of the second protrusion 60 is curved along the recess 52 in a cross-sectional view.
The tip portion 61 has a protruding portion 62 that protrudes toward the bottom surface 52a of the recessed portion 52. In this embodiment, the portion of the tip portion 61 that is located within the recessed portion 52 and abuts against the recessed portion 52 is the protruding portion 62. In other words, the protruding portion 62 is curved along the recessed portion 52 in a cross-sectional view. The protruding portion 62 fits snugly into the recessed portion 52.

As shown in FIG. 2, the protrusion 62 extends in the third direction Z.
As shown in FIG. 3, the height H2 of the second convex portion 60 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less in this embodiment.

As shown in FIG. 2 , a gasket 70 is provided outside the first convex portions 50 and second convex portions 60 in the third direction Z to seal between the separator 30 of one unit cell 90 and the second separator 40 of another unit cell 90 adjacent to that unit cell 90 in the first direction X. The multiple first convex portions 50 and the multiple second convex portions 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.

Next, the operation of this embodiment will be described.
The first protrusion 50 and the second protrusion 60 come into contact with each other with the tip 61 of the second protrusion 60 positioned within the recess 52 of the first protrusion 50. Here, the protrusion 62 of the tip 61 of the second protrusion 60 protrudes toward the bottom surface 52a of the recess 52. Therefore, compared to when a recess is provided in the tip 61 of the second protrusion 60 or when the tip 61 of the second protrusion 60 is flat, a gap is less likely to form between the recess 52 of the first protrusion 50 and the second protrusion 60. This makes it less likely for the coolant to flow to the outside of the first protrusion 50 and the second protrusion 60 through the gap.

Next, the effects of this embodiment will be described.
(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 path 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 recess 52 extending in the third direction Z is provided at the center of the tip 51 of each first protrusion 50 in the second direction Y. The tip 61 of the second protrusion 60 is located within the recess 52 and has a protrusion 62 that protrudes toward the bottom surface 52a of the recess 52.

This configuration provides the above-mentioned effects, and therefore, the side flow of the cooling medium can be suppressed.
(2) The recessed portion 52 is curved with respect to an imaginary line extending in the second direction Y. The protruding portion 62 is curved along the recessed portion 52 and abuts against the recessed portion 52 .

With this configuration, almost no gap is formed between the recessed portion 52 of the first protrusion 50 and the second protrusion 60. Therefore, sideways flow of the cooling medium can be further suppressed.
(3) The first protrusions 50 are provided over the entire area in which the outer groove passage 38 a is formed in the second direction Y. The second protrusions 60 are provided over the entire area in which the outer groove passage 48 a is formed in the second direction Y.

With this configuration, the above-mentioned effect is achieved throughout the entire area in the second direction Y where the outer groove flow paths 38a, 48a are formed. This further reduces sideways flow of the cooling medium.

(4) The first separator 30 and the second separator 40 are made of metal plates.
When the separator 30 is made of a metal plate, recesses 52 are likely to be formed at the tip portions 51 of the first protrusions 50 during molding. When the separator 40 is made of a metal plate, recesses are likely to be formed at the tip portions 61 of the second protrusions 60 during molding.

In this regard, the above-described configuration can suppress sideways flow of the cooling medium caused by the recessed portion.
<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

- 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 exemplified in this embodiment, but may be, for example, an elliptical shape in plan view.

The flow of the reactant gas and coolant in the manifolds 91, 92, 93, 94, 95, and 96 is not limited to that exemplified in this embodiment. For example, manifold 96 may be an inlet manifold for the oxidant gas, and manifold 95 may be an outlet manifold for the oxidant gas. Additionally, manifold 94 may be an inlet manifold for the coolant, and manifold 93 may be an outlet manifold for the coolant. In other words, the oxidant gas flowing through groove flow passage 47A and the coolant flowing through groove flow passages 38A and 48A may flow in the same direction as the fuel gas flowing through groove flow passage 37A.

- The groove flow path 37A (38A) is not limited to extending linearly in the second direction Y, as illustrated in this embodiment. For example, the groove flow path 37A (38A) may extend in a wavy manner in the surface direction of the opposing surface 30a (surface 30b).

- The groove flow path 47A (48A) is not limited to extending linearly in the second direction Y as illustrated in this embodiment. For example, the groove flow path 47A (48A) may extend in a wavy manner in the surface direction of the opposing surface 40a (surface 40b).

The shape of the first convex portion 50 is not limited to the shape exemplified in this embodiment. For example, the height H1 of the first convex portion 50 may be less than 0.2 mm or greater than 0.8 mm. In this case, the height H2 of the second convex portion 60 is not limited to the range of 0.2 mm or more and 0.8 mm or less, and may be changed appropriately to match the height H1 of the first convex portion 50. Furthermore, the width W of the first convex portion 50 is not limited to the range of 0.5 mm or more and 2 mm or less, and may be less than 0.5 mm or greater than 2 mm as long as it is within the range in which the effects of the present invention are achieved.

The first separator 30 and the second separator 40 are not limited to those in which the recessed portion 52 of the first convex portion 50 and the protruding portion 62 of the second convex portion 60 fit together without any gaps, as illustrated in this embodiment. For example, as shown in FIG. 4, the separator 30 and the separator 40 may have a first convex portion 150 and a second convex portion 160 having a recessed portion 152 and a protruding portion 162 that form a gap G between them. In this case, the protruding portion 162 only needs to be located within the recessed portion 152 and abut against the recessed portion 152.

- The second protrusion 60 is not limited to having a tip 61 that curves along the recess 52 in a cross-sectional view, as illustrated in this embodiment. For example, the tip 61 of the second protrusion 60 may have a flat portion extending in the planar direction of the second surface 40B and a protruding portion that protrudes from the flat portion toward the bottom surface 52a of the recess 52.

- The recessed portion 52 is 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 this embodiment. For example, the recessed portion 52 may have a flat bottom surface extending in the planar direction of the second surface 30B.

- The first convex portion 50 is not limited to being provided on the outside of both of the pair of outer groove flow paths 38a, as illustrated in this embodiment. The first convex portion 50 may be provided on the outside of only one of the pair of outer groove flow paths 38a. In this case, the second convex portion 60 is not limited to being provided on the outside of both of the pair of outer groove flow paths 48a, and its arrangement may be changed appropriately to match the first convex portion 50.

The fuel cell stack is not limited to the configuration illustrated in this embodiment, 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, 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 need only abut against the second surface 40B of the separator 40.

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

- The first separator according to the present invention is not limited to being an anode-side separator as illustrated in this 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 an anode-side separator.

D: Depth G: Gap H1, H2: Height S: Space W: Width X: First direction Y: Second direction Z: Third direction 10: MEA
DESCRIPTION OF SYMBOLS 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 surface 30a...Opposite surface 30B...Second surface 30b...Surface 31...Through hole 32...Through hole 33...Through hole 34...Through hole 35...Through hole 36...Through hole 37A...Groove flow path 37B...Connecting portion 38A...Groove flow path 38a...Outer groove flow path 38B...Connecting portion 40...Second separator 40A...First surface 40a...Opposite surface 40B...Second surface 40b...Surface 41...Through hole 42...Through hole 43...Through hole 44...Through hole 45...Through hole 46...Through hole 47A...Groove flow path 47B...Connection portion 48A...Groove flow path 48a...Outer groove flow path 48B...Connection portion 50, 150...First convex portion 51...Tip portion 52, 152...Recessed portion 52a...Bottom surface 60, 160...Second convex portion 61...Tip portion 62, 162...Protrusion portion 70...Gasket 90...Single cell 91...Inlet side manifold 92...Outlet side manifold 93...Inlet side manifold 94...Outlet side manifold 95...Inlet side manifold 96...Outlet side manifold

Claims (4)

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 tip end of the first convex portion is provided with a recessed portion located in a center portion in the second direction and extending in the third direction , and a pair of first protrusions located on both sides of the recessed portion in the second direction ,
the recessed portion is curved with respect to a virtual line extending in the second direction,
a tip end surface of each of the pair of first protrusions is curved with respect to a virtual straight line extending in the second direction and is a curved surface that is continuous with a side surface of the first protrusion in the second direction,
a tip end of the second protrusion is located within the recess and has a second protrusion that protrudes toward a bottom surface of the recess,
The second protrusion is curved along the recess and abuts against the recess.
Fuel cell stack. The entire tip of the second protrusion is curved along the recess.
The fuel cell stack of claim 1 . 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;
3. The fuel cell stack according to claim 1 or 2. The first separator and the second separator are made of metal plates.
The fuel cell stack according to any one of claims 1 to 3.