fuel cell stack

Abstract

To provide a fuel cell stack capable of improving a power generation efficiency of a power generation part.SOLUTION: A fuel cell stack is formed by laminating a plurality of single cells 90 having a MEA, a first separator 30 and a second separator, nipping the MEA. The first separator 30 includes a first groove path 37A in which a fuel gas flows. The first groove path 37A includes: a first main path 51; and a first sub-flow path 52b extended toward an exit side manifold 92. The second separator includes a second groove path in which an oxidant gas flows. The second groove path includes: a second main path; and a second sub-flow path positioned at the side opposite to the first sub-flow path 52b while nipping the MEA. The first sub-flow path 52b includes an extension part 53b extended to an orthogonal direction Z. The second sub-flow path includes an extention part extended to the orthogonal direction Z. An extension part 53b includes a wave-shaped part 54b. The wave-shaped part 54b is crossed while nipping the MEA with the extension part of the second sub-flow path.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a fuel cell stack formed by stacking a plurality of unit cells. Each unit cell has a membrane electrode assembly (hereinafter referred to as a power generation section) and a first metal separator and a second metal separator that sandwich the power generation section.

[0003] In a first direction perpendicular to the stacking direction of the multiple unit cells, an oxidant gas inlet manifold for supplying oxidant gas, a coolant inlet manifold for supplying coolant, and a fuel gas outlet manifold for discharging fuel gas are provided on one end side of the unit cell.

[0004] The oxygen-containing gas supply passage, the coolant supply passage, and the fuel gas discharge passage are arranged in this order in a second direction that is perpendicular to both the stacking direction and the first direction. On the other end side of the unit cell in the first direction, a fuel gas inlet passage for supplying fuel gas, a coolant outlet passage for discharging the coolant, and an oxidant gas outlet passage for discharging the oxidant gas are provided.

[0005] The fuel gas inlet manifold, the coolant outlet manifold, and the oxygen-containing gas outlet manifold are arranged in this order in the second direction. A plurality of oxidant gas flow grooves having an uneven shape are formed on the surface of the first metal separator facing the power generation section.

[0006] The oxidant gas flow groove has a plurality of straight flow section portions (hereinafter referred to as first straight section portions) extending parallel to one another in a first direction, and a plurality of straight connecting flow section portions (hereinafter referred to as first connecting section portions) extending from both ends of the first straight section to the oxidant gas inlet manifold and the oxidant gas outlet manifold.

[0007] The first connecting portion extends at an angle relative to the first linear portion. A plurality of fuel gas flow grooves having an uneven shape are formed on the surface of the second metal separator facing the power generation section.

[0008] The fuel gas flow groove has a plurality of straight flow path sections (hereinafter referred to as second straight flow sections) extending parallel to each other in a first direction, and a plurality of straight connecting flow path sections (hereinafter referred to as second connecting sections) extending from both ends of the second straight flow sections to the fuel gas inlet manifold and the fuel gas outlet manifold.

[0009] The second connecting portion extends at an angle relative to the second linear portion. In this fuel cell stack, the flow of oxidant gas in the first straight section and the flow of fuel gas in the second straight section are opposite to each other across the power generation section, which is a so-called counterflow, while the flow of oxidant gas in the first connecting section and the flow of fuel gas in the second connecting section cross each other across the power generation section, which is a so-called crossflow. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-59513 Summary of the Invention [Problem to be solved by the invention]

[0011] Generally, the power generation efficiency of the region of the power generation section corresponding to the counter flow tends to be higher than the power generation efficiency of the region of the power generation section corresponding to the cross flow. Therefore, in the fuel cell stack described in Patent Document 1, the power generation efficiency of the region of the power generation section corresponding to the first connecting portion and the second connecting portion tends to be lower than the power generation efficiency of the region of the power generation section corresponding to the first straight portion and the second straight portion.

[0012] For this reason, in order to improve the power generation efficiency of the power generation section, it is desirable to increase the area of ​​the portion where the straight portions are formed on the surface of each separator facing the power generation section, while reducing the area of ​​the portion where the connecting portions are formed.

[0013] Therefore, for example, it is conceivable to provide the connecting portions so that they extend linearly in the second direction from both sides of the straight portion. However, in such a fuel cell stack, the flow of oxidant gas in the first connecting portion and the flow of fuel gas in the second connecting portion are in the same direction across the power generation portion, resulting in a so-called coflow. In this case, the power generation efficiency of the region of the power generation portion corresponding to the first and second connecting portions is lower than the power generation efficiency of the region of the power generation portion corresponding to the first and second straight portions, so there is still room for improvement in power generation efficiency.

[0014] An object of the present invention is to provide a fuel cell stack that can improve the power generation efficiency of the power generation section. [Means for solving the problem]

[0015] A fuel cell stack for achieving the above object is a fuel cell stack formed by stacking a plurality of unit cells, each unit cell having a power generation section and a first separator and a second separator that sandwich the power generation section, wherein the unit cells are provided with a plurality of manifolds that penetrate the unit cells in the stacking direction of the unit cells and through which a fuel gas or an oxidant gas flows, on the outer circumferential side of the power generation section, the plurality of manifolds including a fuel gas inlet side manifold for supplying the fuel gas into the unit cells, a fuel gas outlet side manifold for discharging the fuel gas inside the unit cells, an oxidant gas inlet side manifold for supplying the oxidant gas into the unit cells, and an oxidant gas outlet side manifold for discharging the oxidant gas inside the unit cells, and the fuel gas inlet side manifold and the oxidant gas outlet side manifold are arranged in this order from one side in a second direction that is orthogonal to both the stacking direction and the first direction on one side of the unit cells in a first direction that is orthogonal to the stacking direction and the first direction, and the oxidant gas inlet side manifold and the oxidant gas outlet side manifold are arranged on the other side of the unit cells in the first direction. and the fuel gas outlet side manifold are arranged in order from one side in the second direction, the first separator has a plurality of first groove flow paths through which the fuel gas flows on an opposing surface facing the power generation section, the plurality of first groove flow paths having a plurality of first main flow paths extending in the first direction and arranged in the second direction, and a plurality of first sub-flow paths adjacent to the plurality of first main flow paths in the first direction and extending toward at least one of the fuel gas inlet side manifold and the fuel gas outlet side manifold, a plurality of second groove channels through which the oxidant gas flows is provided on an opposing surface facing the power generation unit, the plurality of second groove channels including a plurality of second main channels extending in the first direction and aligned in the second direction, and a plurality of second sub-channels located on the opposite side of the power generation unit from the plurality of first sub-channels, both of the first sub-channels and the second sub-channels including an extending portion extending in the second direction, the extending portion of at least one of the first sub-channels and the second sub-channels having a wavy portion that forms a wavy shape in a planar direction of the opposing surface, the wavy portion comprising:The power generating unit is intersected with the extending portion of the other of the first sub-channel and the second sub-channel, which is different from the one of the first sub-channel and the second sub-channel.

[0016] According to this configuration, when the extending portion of the first sub-channel has a wavy portion, the flow of fuel gas in the wavy portion of the first sub-channel and the flow of oxidant gas in the extending portion of the second sub-channel intersect with each other across the power generation unit, forming a so-called crossflow. Furthermore, when the extending portion of the second sub-channel has a wavy portion, the flow of fuel gas in the extending portion of the first sub-channel and the flow of oxidant gas in the wavy portion of the second sub-channel also crossflow. Therefore, the power generation efficiency of the regions of the power generation unit corresponding to the first and second sub-channels can be improved compared to when the extending portions of both the first and second sub-channels extend linearly in the second direction.

[0017] Furthermore, with the above configuration, both the first sub-channel and the second sub-channel include an extending portion extending in the second direction. Therefore, compared to when the first sub-channel and the second sub-channel extend at an angle relative to the first main channel and the second main channel, respectively, the area of ​​the portion where the first sub-channel and the second sub-channel are formed on the opposing surfaces of the separators can be made smaller. In other words, the area of ​​the portion where the first main channel and the second main channel are formed on the opposing surfaces of the separators can be made larger.

[0018] Therefore, the power generation efficiency of the power generation section can be improved. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is an exploded perspective view showing an embodiment of a fuel cell stack. [Figure 2] FIG. 2 is a plan view showing a first separator of a unit cell of the fuel cell stack of FIG. [Figure 3] FIG. 3 is a bottom view showing a second separator of a unit cell of the fuel cell stack of FIG. [Figure 4]FIG. 4 is a plan view showing how the flow of fuel gas flowing through the wavy portion of the first groove flow path and the flow of oxidant gas flowing through the extended portion of the second groove flow path intersect with the power generation unit in between. [Figure 5] FIG. 5 is a plan view corresponding to FIG. 4, showing how the flows of fuel gas and oxidant gas intersect with each other across the power generation section in a modified example of the fuel cell stack. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of a fuel cell stack will now be described with reference to FIGS. <Basic configuration of fuel cell stack> As shown in Fig. 1, 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. Fig. 1 also shows a unit cell 90 of the fuel cell stack with each component separated, and a part of another unit cell 90 adjacent to the unit cell 90.

[0021] Hereinafter, the stacking direction of the plurality of unit cells 90 will be simply referred to as the stacking direction X, the longitudinal direction of the unit cells 90 among the directions perpendicular to the stacking direction X will be simply referred to as the longitudinal direction Y, and the direction perpendicular to both the stacking direction X and the longitudinal direction Y will be simply referred to as the orthogonal direction Z. The longitudinal direction Y corresponds to the first direction according to the present invention, and the orthogonal direction Z corresponds to the second direction according to the present invention.

[0022] The unit cell 90 has a membrane electrode assembly (hereinafter, 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] The unit cell 90 has inlet side manifolds 91, 93, and 95 for supplying the reaction gas or cooling medium into the unit cell 90, and outlet side manifolds 92, 94, and 96 for discharging the reaction gas or cooling medium inside the unit cell 90 to the outside.

[0024] The inlet side manifold 91 and the outlet side manifold 92 are manifolds through which a fuel gas, which is one of the reaction gases, 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, which is one of the reaction gases, flows. The oxidizer gas is, for example, air.

[0025] The inlet side manifolds 91, 93, 95 and the outlet side manifolds 92, 94, 96 are rectangular in plan view and penetrate each unit cell 90 in the stacking 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 longitudinal direction Y. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are lined up in order from one side (the back side of the paper in FIG. 1) to the other side (the front side of the paper in FIG. 1) in the orthogonal direction Z.

[0026] 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 longitudinal 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 orthogonal direction Z.

[0027] <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 stacking 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 stacking direction X (the lower side in FIG. 1) is the anode electrode 12.

[0028] 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 generation section according to the present invention.

[0029] <Frame member 20> As shown in FIG. 1, the frame member 20 has a rectangular frame shape in a plan view, and is made of, for example, a synthetic resin material.

[0030] 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 stacking direction X (the upper side in FIG. 1).

[0031] <First separator 30> As shown in FIGS. 1 and 2, the first separator 30 has a rectangular shape in a plan view, and is formed by press-forming a metal plate made of, for example, titanium or stainless steel.

[0032] 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 an opposing surface 30a that faces the anode electrode 12 of the MEA 10 in the stacking direction X, and a second surface 30B opposite to the first surface 30A.

[0033] The first surface 30A is provided with a plurality of first groove channels 37A and a plurality of first connection channels 37B (see FIG. 2) through which the fuel gas flows. The plurality of first groove channels 37A and the plurality of first connection channels 37B are formed by molding the separator 30 into an uneven shape.

[0034] A plurality of first groove channels 37A are provided on the opposing surface 30a. Note that the first groove channels 37A are shown in a simplified form in FIG. As shown in FIG. 2, the plurality of first groove flow paths 37A include a plurality of first main flow paths 51 and a plurality of first sub-flow paths 52a and 52b.

[0035] The first main channels 51 extend linearly in the longitudinal direction Y and are arranged in the perpendicular direction Z at intervals. The multiple (three in this embodiment) first sub-channels 52a extend from one end of the first main channel 51 in the longitudinal direction Y (the left end in the left-right direction in FIG. 2) toward the inlet manifold 91.

[0036] Each of the multiple first sub-channels 52a is provided with an extending portion 53a extending in the perpendicular direction Z. The extending portions 53a are arranged at intervals from each other in the longitudinal direction Y. Multiple (five or six in this embodiment) end portions of one side (the left side in FIG. 2) of the first main channel 51 are connected to each extending portion 53a of the first sub-channels 52a.

[0037] The extending portion 53a has a wavy portion 54a that is wavy in the planar direction of the opposing surface 30a. In this embodiment, the extending portion 53a on the furthest side in the longitudinal direction Y (the left side in FIG. 2) has the wavy portion 54a.

[0038] The plurality of (three in this embodiment) first sub-channels 52b extend from the other end of the first main channel 51 in the longitudinal direction Y (the right side in FIG. 2) toward the outlet manifold 92. Each of the multiple first sub-channels 52b is provided with an extending portion 53b extending in the perpendicular direction Z. The extending portions 53b are arranged at intervals from each other in the longitudinal direction Y. Multiple (five or six in this embodiment) end portions of the first main channel 51 on the other side (the right side in FIG. 2) are connected to each extending portion 53b of the first sub-channels 52b.

[0039] The extending portion 53b has a wavy portion 54b that is wavy in the planar direction of the opposing surface 30a. In this embodiment, the extending portion 53b on the other side (the right side in FIG. 2) in the longitudinal direction Y has the wavy portion 54b.

[0040] As shown in FIG. 2, the plurality of first connection flow paths 37B constitute a plurality of connection flow paths 97 that connect the first sub-flow paths 52a and the inlet side manifold 91, and the first sub-flow paths 52b and the outlet side manifold 92.

[0041] The first connection flow paths 37B extend from the first sub-flow paths 52a, 52b outward beyond the opposing surface 30a, and are arranged in the orthogonal direction Z at intervals from one another. 2, the portions of the plurality of connection flow paths 97 other than the first connection flow path 37B (hereinafter referred to as connection flow paths 28A) are provided between the plurality of ribs 28B protruding from the frame member 20 toward the first surface 30A. Note that the connection flow paths 28A and the ribs 28B are not shown in FIG.

[0042] The fuel gas is introduced from the inlet manifold 91 into the plurality of first groove flow paths 37A via the plurality of connecting flow paths 97. Thereafter, the fuel gas flows through the first sub-flow path 52a, the first main flow path 51, and the first sub-flow path 52b in this order, and is discharged to the outlet manifold 92.

[0043] As shown in Fig. 1, the second surface 30B is provided with a plurality of groove channels 38 through which the coolant flows. The plurality of groove channels 38 communicate with an inlet-side manifold 93 and an outlet-side manifold 94. The plurality of groove channels 38 are formed by molding the separator 30 into an uneven shape, and some of the groove channels 38 are formed integrally with the uneven shape that constitutes the plurality of first groove channels 37A (see Fig. 2). Note that Fig. 1 shows the groove channels 38 in a simplified form.

[0044] <Second separator 40> As shown in FIGS. 1 and 3, the second separator 40 has a rectangular shape in a plan view, and is formed by press-forming a metal plate made of, for example, titanium or stainless steel.

[0045] 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 an opposing surface 40a that faces the cathode electrode 11 of the MEA 10 in the stacking direction X, and a second surface 40B opposite to the first surface 40A.

[0046] The first surface 40A is provided with a plurality of second groove channels 47A and a plurality of second connection channels 47B (see FIG. 3) through which the fuel gas flows. The plurality of second groove channels 47A and the plurality of second connection channels 47B are formed by molding the separator 40 into an uneven shape.

[0047] A plurality of second grooves 47A are provided on the opposing surface 40a. Note that the second grooves 47A are shown in a simplified form in FIG. As shown in FIG. 3, the plurality of second groove flow paths 47A include a plurality of second main flow paths 61 and a plurality of second sub-flow paths 62a and 62b.

[0048] The second main channels 61 extend linearly in the longitudinal direction Y and are arranged in the perpendicular direction Z at intervals. The plurality of (three in this embodiment) second sub-channels 62a extend from the other end of the second main channel 61 in the longitudinal direction Y (the left end in the left-right direction in FIG. 3) toward the inlet manifold 95.

[0049] As shown in FIGS. 2 and 3, the second sub-channels 62a are located on the opposite side of the MEA 10 from the first sub-channels 52b. 3, each of the multiple second sub-flow paths 62a is provided with an extending portion 63a that extends linearly in the orthogonal direction Z. The extending portions 63a are arranged at intervals from each other in the longitudinal direction Y. Multiple (five or six in this embodiment) end portions of the second main flow path 61 on the other side (the left side in FIG. 3) are connected to each extending portion 63a of the second sub-flow paths 62a.

[0050] 2 to 4, the extending portion 63a located on the other side (left side in FIG. 3) in the longitudinal direction Y is located on the opposite side of the MEA 10 from the wavy portion 54b. The extending portion 63a and the wavy portion 54b intersect multiple times with the MEA 10 in between (see FIG. 4).

[0051] As shown in FIG. 3, multiple (three in this embodiment) second sub-flow paths 62b extend in the longitudinal direction Y from one end (the right side in FIG. 3) of the second main flow path 61 toward the outlet manifold 96.

[0052] As shown in FIGS. 2 and 3, the second sub-channels 62b are located on the opposite side of the MEA 10 from the first sub-channels 52a. 3, each of the multiple second sub-flow paths 62b is provided with an extending portion 63b that extends linearly in the orthogonal direction Z. The extending portions 63b are arranged at intervals from each other in the longitudinal direction Y. Multiple (five or six in this embodiment) end portions of one side (the right side in FIG. 3) of the second main flow path 61 are connected to each extending portion 63b of the second sub-flow paths 62b.

[0053] 2 and 3, the extending portion 63b located on the furthest side in the longitudinal direction Y (the right side in FIG. 3) is located on the opposite side of the MEA 10 from the wavy portion 54a. The extending portion 63b and the wavy portion 54a intersect multiple times with the MEA 10 in between.

[0054] As shown in FIG. 3, the plurality of second connection flow paths 47B constitute a plurality of connection flow paths 98 that connect the second sub-flow path 62a to the inlet side manifold 95 and the second sub-flow path 62b to the outlet side manifold 96.

[0055] The second connection flow paths 47B extend from the second sub-flow paths 62a, 62b outward beyond the opposing surface 40a, and are arranged in the orthogonal direction Z at intervals. 3, the portions of the plurality of connection flow paths 98 other than the second connection flow path 47B (hereinafter referred to as connection flow paths 29A) are provided between the plurality of ribs 29B protruding from the frame member 20 toward the first surface 40A. Note that the connection flow paths 29A and the ribs 29B are not shown in FIG.

[0056] The oxidizing gas is introduced from the inlet-side manifold 95 into the plurality of second groove flow paths 47A via the plurality of connecting flow paths 98. Thereafter, the oxidizing gas flows through the second sub-flow path 62a, the second main flow path 61, and the second sub-flow path 62b in this order, and is discharged to the outlet-side manifold 96.

[0057] As shown in Fig. 1, the second surface 40B is provided with a plurality of groove channels 48 through which a coolant flows. The plurality of groove channels 48 communicate with an inlet-side manifold 93 and an outlet-side manifold 94. The plurality of groove channels 48 are formed by molding the separator 40 into an uneven shape, and some of the groove channels 48 are formed integrally with the uneven shape that constitutes the plurality of second groove channels 47A (see Fig. 3). Note that Fig. 1 shows the groove channels 48 in a simplified form.

[0058] Next, the operation of this embodiment will be described. 4, a flow F1 of fuel gas in the corrugated portion 54b of the first sub-channel 52b and a flow F2 of oxidant gas in the extended portion 63a of the second sub-channel 62a cross each other across the MEA 10, forming a so-called crossflow. Therefore, compared to when the extended portions 53b, 63a of the first sub-channel 52b and the second sub-channel 62a extend linearly in the orthogonal direction Z, the power generation efficiency of the regions of the MEA 10 corresponding to the first sub-channel 52b and the second sub-channel 62a is improved. Furthermore, although not shown, a crossflow is formed between the flow F1 of fuel gas in the corrugated portion 54a of the first sub-channel 52a and the flow F2 of oxidant gas in the extended portion 63b of the second sub-channel 62b. Therefore, the power generation efficiency of the areas corresponding to the first sub-channel 52a and the second sub-channel 62b in the MEA 10 is improved compared to when the extension portions 53a, 63b of both the first sub-channel 52a and the second sub-channel 62b extend linearly in the perpendicular direction Z.

[0059] Next, the effects of this embodiment will be described. (1) The first groove channels 37A each have a plurality of first main channels 51 extending linearly in the longitudinal direction Y and aligned in the orthogonal direction Z, and a plurality of first sub-channels 52b adjacent to the first main channels 51 in the longitudinal direction Y and extending toward the outlet manifold 92. The second groove channels 47A each have a plurality of second main channels 61 extending linearly in the longitudinal direction Y and aligned in the orthogonal direction Z, and a plurality of second sub-channels 62a located on the opposite side of the MEA 10 from the first sub-channels 52b. The first sub-channels 52b each have an extending portion 53b extending in the orthogonal direction Z. The second sub-channel 62a each have an extending portion 63a extending linearly in the orthogonal direction Z. The extending portion 53b of the first sub-channel 52b each have a wavy portion 54b that is wavy in the plane direction of the opposing surface 30a. The wavy portion 54b intersects with the extending portion 63a of the second sub-channel 62a with the MEA 10 interposed therebetween.

[0060] This configuration provides the above-mentioned effects. Furthermore, with the above configuration, both the first sub-channel 52b and the second sub-channel 62a have extending portions 53b, 63a extending in the perpendicular direction Z. Therefore, the area of ​​the portion where the first sub-channel 52b and the second sub-channel 62a are formed on the opposing surfaces 30a, 40a of each separator 30, 40 can be made smaller than when, for example, the first sub-channel 52b and the second sub-channel 62a extend at an angle relative to the first main channel 51 and the second main channel 61, respectively. In other words, the area of ​​the portion where the first main channel 51 and the second main channel 61 are formed on the opposing surfaces 30a, 40a of each separator 30, 40 can be made larger.

[0061] Therefore, the power generation efficiency of the MEA 10 can be improved. (2) The first groove channels 37A have a plurality of first sub-channels 52a that are adjacent to the first main channels 51 in the longitudinal direction Y and extend toward the inlet-side manifold 91. The second groove channels 47A have a plurality of second sub-channels 62b that are located on the opposite side of the MEA 10 from the first sub-channels 52a. The first sub-channels 52a have an extending portion 53a that extends in the perpendicular direction Z. The second sub-channels 62b have an extending portion 63b that extends linearly in the perpendicular direction Z. The extending portion 53a of the first sub-channel 52a has a wavy portion 54a that is wavy in the planar direction of the opposing surface 30a. The wavy portion 54a intersects with the extending portion 63b of the second sub-channel 62b across the MEA 10.

[0062] According to this configuration, the same effect as that of (1) is exerted in the plurality of first sub-channels 52a extending from the plurality of first main channels 51 toward the inlet-side manifold 91 and the plurality of second sub-channels 62b extending from the plurality of second main channels 61 toward the outlet-side manifold 96. This makes it possible to improve the power generation efficiency over a wider range of the MEA 10.

[0063] (3) Only the extending portions 53a (53b) of the plurality of first sub-flow paths 52a (52b) have the wavy portions 54a (54b). The produced water generated in the MEA 10 is discharged through the second groove flow path 47A to the outlet-side manifold 96. When the extension portion 63a (63b) of the second sub-flow path 62a (62b) has a wavy portion, the produced water is less likely to flow through the extension portion 63a (63b) than when the extension portion 63a (63b) extends linearly in the orthogonal direction Z.

[0064] In this regard, according to the above configuration, only the extending portions 53a (53b) of the plurality of first sub-flow paths 52a (52b) have the wavy portions 54a (54b). Therefore, compared to when the extending portions 63a (63b) of the second sub-flow paths 62a (62b) have wavy portions, the generated water is more efficiently discharged to the outlet manifold 96 via the second groove flow paths 47A. Therefore, the generated water can be efficiently discharged while improving the power generation efficiency of the MEA 10.

[0065] <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.

[0066] 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 this embodiment. For example, the shapes of the manifolds 91, 92, 93, 94, 95, 96 may be quadrangular in plan view, including squares, or polygonal in plan view, including triangles and pentagons. Furthermore, they may be circular in plan view, including ellipses and ovals.

[0067] The first main flow path 51 is not limited to extending linearly in the longitudinal direction Y as illustrated in this embodiment. For example, the first main flow path 51 may have a wavy portion that extends wavy in the planar direction of the opposing surface 30a.

[0068] The second main flow path 61 is not limited to extending linearly in the longitudinal direction Y as illustrated in this embodiment. For example, the second main flow path 61 may have a wavy portion that extends wavy in the planar direction of the opposing surface 40a.

[0069] The number of first main channels 51 is not limited to the number exemplified in this embodiment and may be changed as appropriate to suit the specifications of the separator 30. Furthermore, the number of first sub-channels 52a, 52b is not limited to three as exemplified in this embodiment and may be, for example, four or more. Furthermore, the number of first main channels 51 connected to each of the multiple first sub-channels 52a and the number of first main channels 51 connected to each of the multiple first sub-channels 52b are not limited to five or six as exemplified in this embodiment and may be changed as appropriate in accordance with the above-mentioned changes.

[0070] The number of second main channels 61 is not limited to the number exemplified in this embodiment and may be changed as appropriate to suit the specifications of the separator 40. Furthermore, the number of second sub channels 62a, 62b is not limited to three as exemplified in this embodiment and may be, for example, four or more. Furthermore, the number of second main channels 61 connected to each of the multiple second sub channels 62a and the number of second main channels 61 connected to each of the multiple second sub channels 62b are not limited to five or six as exemplified in this embodiment and may be changed as appropriate in accordance with the above-mentioned changes.

[0071] The plurality of first sub-flow paths 52a are not limited to those in which only the extending portion 53a on the furthest side in the longitudinal direction Y (the left side in FIG. 2) has the wavy portion 54a, as exemplified in this embodiment. That is, the plurality of first sub-flow paths 52a may have a plurality of wavy portions 54a. In this case, it is sufficient that the plurality of wavy portions 54a are located on the opposite side of the MEA 10 from the plurality of extending portions 63b and intersect with the extending portions 63b with the MEA 10 in between.

[0072] The plurality of first sub-flow paths 52b are not limited to those in which only the extension portion 53b on the othermost side in the longitudinal direction Y (the right side in FIG. 2) has the wavy portion 54b, as exemplified in this embodiment. That is, the plurality of first sub-flow paths 52b may have a plurality of wavy portions 54b. In this case, it is sufficient that the plurality of wavy portions 54b are located on the opposite side of the MEA 10 from the plurality of extension portions 63a and intersect with the extension portions 63a with the MEA 10 in between.

[0073] As long as the first sub-channel 52a includes the extending portion 53a, it may have a portion that extends at an angle with respect to the first main channel 51. Similarly, as long as the first sub-channel 52b includes the extending portion 53b, it may also have a portion that extends at an angle with respect to the first main channel 51.

[0074] The second sub-channel 62a may have a portion that extends at an angle relative to the second main channel 61, provided that it includes the extending portion 63a. Similarly, the second sub-channel 62b may have a portion that extends at an angle relative to the second main channel 61, provided that it includes the extending portion 63b.

[0075] The extending portion 63a is not limited to extending linearly in the orthogonal direction Z as illustrated in this embodiment. For example, as shown in Fig. 5, the extending portion 63a may have a wavy portion 64a that extends wavy in the orthogonal direction Z. Similarly, although not shown, the extending portion 63b may have a wavy portion that extends wavy in the orthogonal direction Z.

[0076] The multiple first sub-channels 52a (52b) may be omitted. In this case, the first groove channel 37A may have, instead of the first sub-channels 52a (52b), multiple sub-channels extending at an angle relative to the first main channel 51, connecting the first main channel 51 and the connecting channel 97. In addition, in conjunction with this change, the second sub-channel 62b (62a) located on the opposite side of the MEA 10 from the multiple sub-channels may be omitted. In this case, the second groove channel 47A may have, instead of the second sub-channel 62b (62a), multiple sub-channels extending at an angle relative to the second main channel 61, connecting the second main channel 61 and the connecting channel 98.

[0077] The first separator 30 and the second separator 40 are not limited to those formed by press-forming a metal plate material, but may also be formed by, for example, cutting or etching.

[0078] The material of the first separator 30 and the second separator 40 is not limited to titanium or stainless steel, but may also be aluminum. Also, materials other than metals, such as carbon, may be used. [Explanation of symbols]

[0079] F1...flow F2...flow X: stacking direction Y: Longitudinal direction Z: Perpendicular 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 28A...connecting flow path 28B...Rib 29A...connecting flow path 29B...Rib 30...First separator 30A…First side 30a...Opposing surface 30B…Second side 31...Through hole 32...Through hole 33...Through hole 34...Through hole 35...Through hole 36...Through hole 37A…First groove channel 37B...First connecting flow path 38…Groove channel 40...Second separator 40A...Page 1 40a...opposing surface 40B…Second side 41...Through hole 42...Through hole 43...Through hole 44...Through hole 45...Through hole 46...Through hole 47A…Second groove channel 47B...Second connecting flow path 48...Groove channel 51...First main flow path 52a...First sub-channel 52b...First sub-channel 53a...extension part 53b...extension part 54a...Wavy part 54b…Wavied part 61…Second main flow path 62a...Second sub-channel 62b…Second sub-channel 63a...extension part 63b...extension part 64a...Wavy part 90...single cell 91...Inlet manifold 92...Outlet manifold 93...Inlet manifold 94...Outlet manifold 95...Inlet manifold 96...Outlet manifold 97...Connecting channel 98...Connecting channel

Claims

1. A fuel cell stack formed by stacking a plurality of unit cells, each unit cell having a power generation section and a first separator and a second separator sandwiching the power generation section, the unit cells are provided with a plurality of manifolds on an outer circumferential side of the power generation section, the manifolds penetrating the unit cells in a stacking direction of the unit cells and through which a fuel gas or an oxidant gas flows; the plurality of manifolds include a fuel gas inlet side manifold for supplying the fuel gas into the unit cell, a fuel gas outlet side manifold for discharging the fuel gas inside the unit cell, an oxidizer gas inlet side manifold for supplying the oxidizer gas into the unit cell, and an oxidizer gas outlet side manifold for discharging the oxidizer gas inside the unit cell, the fuel gas inlet side manifold and the oxidant gas outlet side manifold are arranged in this order from one side of the unit cell in a first direction perpendicular to the stacking direction to one side of the unit cell in a second direction perpendicular to both the stacking direction and the first direction, the oxidant gas inlet side manifold and the fuel gas outlet side manifold are arranged in this order from one side in the second direction on the other side of the unit cell in the first direction, the first separator has a plurality of first groove channels through which the fuel gas flows, on a surface facing the power generation section; the plurality of first groove flow paths include a plurality of first main flow paths extending in the first direction and aligned in the second direction, and a plurality of first sub-flow paths adjacent to the plurality of first main flow paths in the first direction and extending toward at least one of the fuel gas inlet manifold and the fuel gas outlet manifold, the second separator has a plurality of second groove channels through which the oxidant gas flows on a surface facing the power generation section, the second groove flow paths include a plurality of second main flow paths extending in the first direction and aligned in the second direction, and a plurality of second sub-flow paths located on the opposite side of the power generation unit from the plurality of first sub-flow paths, both the first sub-channel and the second sub-channel include an extending portion extending in the second direction, only the extending portion of the first sub-flow path out of the first sub-flow path and the second sub-flow path has a wavy portion that forms a wavy shape in a planar direction of the opposing surface, the wavy portion intersects with the extending portion of the other of the first sub-channel and the second sub-channel, the other being different from the one of the first sub-channel and the second sub-channel, with the power generation unit interposed therebetween. Fuel cell stack.

2. the plurality of first sub-flow paths extend toward both the fuel gas inlet manifold and the fuel gas outlet manifold. The fuel cell stack of claim 1 .

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