Separators for fuel cells

Abstract

To provide a fuel cell separator capable of suppressing reduction in flow rate of a reaction gas getting into a gas diffusion layer at a downstream side of groove flow channels.SOLUTION: A fuel cell separator 30 has an abutting surface 30a abutting on an MEA (Membrane Electrode Assembly) of a fuel cell. A plurality of groove flow channels 37 in which a fuel gas circulates are arranged on the abutting surface 30a. The groove flow channels 37 extend in an undulating form in a surface direction of the abutting surface 30a and have a plurality of branch channels 73 (74) and a joining part 71a (71b, 71c) where the plurality of branch channels 73 (74) merge from the upstream side toward the downstream side.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses a unit cell that constitutes a fuel cell stack. This unit cell has a membrane electrode assembly (hereinafter, MEA) and a first separator and a second separator that sandwich the MEA.

[0003] The MEA has a catalyst coated membrane (hereinafter, CCM) having an electrolyte membrane and a catalyst layer, and gas diffusion layers (hereinafter, GDLs) provided on both sides of the CCM.

[0004] The first separator has a plurality of first groove channels for oxidizing gas and a plurality of cooling groove channels for a cooling medium. The first groove channels are linear and formed on the surface of the first separator facing the MEA. The unevenness of the first groove channels and the unevenness of the cooling groove channels are inextricably linked.

[0005] The second separator has a plurality of second groove channels for fuel gas and a plurality of cooling groove channels for a cooling medium. The second groove channels are wavy and formed on the surface of the second separator facing the MEA. The unevenness of the second groove channels and the unevenness of the cooling groove channels are inextricably linked. The amplitude of the second groove channels is set to a size such that they overlap with a plurality of convex portions constituting the back surface of the plurality of first groove channels in the first separator facing the second separator.

[0006] When such unit cells are stacked, the contact area between the convex portion constituting the second groove flow passage of one unit cell and the convex portion constituting the back surface of the first groove flow passage of the other unit cell is increased, improving the stability of the contact structure between adjacent separators and, ultimately, the stability of the contact structure between unit cells. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-78020 A Summary of the Invention [Problem to be solved by the invention]

[0008] In such a unit cell, the fuel gas flowing through the second groove is gradually consumed from the upstream to downstream of the groove during power generation. Therefore, the flow rate of the fuel gas decreases downstream of the groove, and the flow rate of the fuel gas entering the GDL tends to decrease accordingly. As a result, the amount of power generation downstream of the groove may decrease.

[0009] It should be noted that this problem is not limited to separators having grooves for fuel gas, but also occurs in separators having grooves for oxidizing gas. An object of the present invention is to provide a separator for a fuel cell that can suppress a decrease in the flow rate of a reactant gas that penetrates into a gas diffusion layer on the downstream side of a groove flow path. [Means for solving the problem]

[0010] To achieve the above-mentioned objective, a separator for a fuel cell has an abutment surface that abuts against a power generation unit of the fuel cell, and a plurality of groove channels through which a reactant gas flows are arranged side by side on the abutment surface, and when the upstream side and downstream side of the flow direction of the reactant gas in the groove channel are defined as the upstream side and the downstream side, the groove channel extends in a wavy manner in the planar direction of the abutment surface, and has a plurality of tributary channels and a junction portion where the plurality of tributary channels merge from the upstream side to the downstream side.

[0011] As the reactant gas flows through the groove of the separator, it gradually penetrates into the power generation section adjacent to the separator, more specifically, into the gas diffusion layer constituting the power generation section. Here, according to the above configuration, in the groove, a plurality of branch channels extend upstream of the junction. Therefore, the reactant gas flowing through the plurality of branch channels in the groove joins at the junction and flows downstream. Here, the pressure loss of the reactant gas downstream of the junction in the groove is greater than the pressure loss of the reactant gas upstream of the junction. This promotes the reactant gas to penetrate into the gas diffusion layer downstream of the junction in the groove. Therefore, it is possible to suppress a decrease in the flow rate of the reactant gas penetrating into the gas diffusion layer downstream of the junction in the groove. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is an exploded perspective view showing a unit cell of the fuel cell. [Diagram 2] FIG. 2 is a plan view showing an embodiment of a separator for a fuel cell, in which a plurality of groove channels through which a fuel gas flows are arranged side by side. [Diagram 3] Cross-sectional view taken along line 3-3 in Figure 2. [Figure 4] Cross-sectional view taken along line 4-4 in Figure 2. [Diagram 5] FIG. 4 is a cross-sectional view showing the flow of fuel gas entering a gas diffusion layer from a groove flow path. [Figure 6] FIG. 4 is a cross-sectional view showing the flow of fuel gas entering a gas diffusion layer from a groove flow path. [Figure 7] FIG. 11 is a plan view showing a modified example of a groove flow path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, one embodiment of a separator for a fuel cell will be described with reference to FIGS. <Overall configuration of a single cell in a fuel cell stack> As shown in FIG. 1, a single cell of the fuel cell stack has a membrane electrode assembly 10 (hereinafter, MEA 10), a frame member 20 that supports the MEA 10, and a pair of separators 30, 40 that hold the MEA 10 and the frame member 20 therebetween.

[0014] The unit cell as a whole has a rectangular plate shape. In the following description, the stacking direction of the separator 30, the MEA 10, the frame member 20, and the separator 40 is referred to as a first direction X.

[0015] Further, the description will be given assuming that the second direction Y is the longitudinal direction of the unit cell and perpendicular to the first direction X. Moreover, a direction perpendicular to both the first direction X and the second direction Y is referred to as a third direction Z in the following description.

[0016] The single cell has inlet holes 91, 93, 95 for introducing a reactant gas or a cooling medium into the single cell, and outlet holes 92, 94, 96 for discharging the reactant gas and the cooling medium in the single cell to the outside. In this embodiment, the inlet hole 91 and the outlet hole 92 are holes through which a fuel gas flows. The inlet hole 93 and the outlet hole 94 are holes through which a cooling medium flows. The inlet hole 95 and the outlet hole 96 are holes through which an oxidizer gas flows. Here, the fuel gas is hydrogen gas. The cooling medium is cooling water. The oxidizer gas is air.

[0017] The inlet holes 91, 93, 95 and the outlet holes 92, 94, 96 have a rectangular shape in plan view that is long in the second direction Y, and penetrate the unit cell in the first direction X. The inlet hole 91 and the outlet holes 94, 96 are provided on one side of the unit cell in the second direction Y (the left side in the left-right direction in FIG. 1). The inlet hole 91 and the outlet holes 94, 96 are aligned in the third direction Z with a gap between them. The outlet hole 92 and the inlet holes 93, 95 are provided on the other side of the unit cell in the second direction Y (the right side in FIG. 1). The outlet hole 92 and the inlet holes 93, 95 are aligned in the third direction Z with a gap between them.

[0018] <mea10> As shown in FIG. 1, the MEA 10 has a rectangular shape that is long in the second direction Y when viewed from above. The MEA 10 has a solid polymer electrolyte membrane (hereinafter, electrolyte membrane) (not shown) and electrodes 11A, 11B provided on both sides of the electrolyte membrane. In this embodiment, the electrode bonded to one side (upper side in the vertical direction in FIG. 1) of the electrolyte membrane (not shown) in the first direction X is the cathode electrode 11A. The electrode bonded to the other side (lower side in FIG. 1) of the electrolyte membrane in the first direction X is the anode electrode 11B.

[0019] The electrodes 11A and 11B each have a catalyst layer (not shown) bonded to the electrolyte membrane, and a gas diffusion layer 12 (hereinafter, GDL 12) bonded to the catalyst layer. The MEA 10 corresponds to the power generating section of the fuel cell according to the present invention.

[0020] <Frame member 20> As shown in FIG. 1, the frame member 20 has a rectangular frame shape that is long in the second direction Y. The frame member 20 is made of, for example, a hard resin material.

[0021] The frame member 20 has through holes 21, 22, 23, 24, 25, and 26 which form the holes 91, 92, 93, 94, 95, and 96. The frame member 20 has, in the center, an opening 27 that is rectangular in plan view and long in the second direction Y. The MEA 10 is joined to the edge of the opening 27 from one side in the first direction X (the upper side in FIG. 1).

[0022] <Separator 30> As shown in FIG. 1, the separator 30 has a rectangular plate shape that is elongated in the second direction Y when viewed from above. The separator 30 is formed by press-molding a metal member such as titanium or stainless steel.

[0023] The separator 30 is provided on the anode electrode 11B side of the MEA 10. The separator 30 has a first surface 30A including a contact surface 30a (see FIG. 2) that contacts the MEA 10, and a second surface 30B opposite to the first surface 30A.

[0024] The separator 30 has through holes 31, 32, 33, 34, 35, and 36 which constitute the holes 91, 92, 93, 94, 95, and 96. The through holes 31, 34, and 36 are provided at positions corresponding to the through holes 21, 24, and 26 of the frame member 20 in the third direction Z. The through holes 32, 33, and 35 are provided at positions corresponding to the through holes 22, 23, and 25 of the frame member 20 in the third direction Z.

[0025] The separator 30 has a plurality of groove channels 37 through which a fuel gas flows, and a plurality of groove channels 38 through which a cooling medium flows. Note that Fig. 1 shows a simplified view of the outer edge of a portion of the separator 30 where the plurality of groove channels 37 are formed, and the outer edge of a portion of the separator 30 where the plurality of groove channels 38 are formed.

[0026] <Groove channel 37,38> 2, the plurality of groove channels 37 are grooves that connect the through holes 31 and 32. The plurality of groove channels 37 are provided on the first surface 30A. In this embodiment, four groove channels 37 are arranged at intervals in the third direction Z. That is, the four groove channels 37 are independent of each other.

[0027] In the following description, the upstream side and the downstream side of the groove 37 in the flow direction of the fuel gas will simply be referred to as the upstream side and the downstream side. The groove width of the groove 37, i.e., the cross-sectional area of ​​the groove 37, is constant over the entirety in the extending direction of the groove 37. The groove widths of the grooves 37 are the same as each other.

[0028] 2, the groove flow passage 37 is provided on the contact surface 30a and has a wavy portion 70 extending in a wavy manner in the surface direction of the contact surface 30a. The amplitude A of the wavy portion 70 on the downstream side is larger than the amplitude A of the wavy portion 70 on the upstream side. More specifically, the amplitude A of the wavy portion 70 is larger on the downstream side.

[0029] The wavy portion 70 has confluences 71a, 71b, and 71c. In addition, the wavy portion 70 has a main flow path 72 located downstream of the wavy portion 70, a plurality of first tributary flow paths 73 that merge into the main flow path 72, and a plurality of second tributary flow paths 74 that merge into each of the first tributary flow paths 73.

[0030] Furthermore, the wavy portion 70 has connecting flow paths 75 that connect to the second branch flow paths 74 on the upstream side of the wavy portion 70 . The junction 71 a is provided at the upstream end of the main flow path 72 .

[0031] The first branch channels 73 extend from the upstream side toward the junction 71a. More specifically, two first branch channels 73 join together at the junction 71a. The first tributary channels 73 are independent of each other except at the junction 71a. More specifically, the first tributary channels 73 are arranged side by side at an interval S1 in the third direction Z. The first tributary channels 73 have portions that extend parallel to each other.

[0032] The junctions 71b and 71c are provided at the upstream ends of the two first branch channels 73. The junctions 71b and 71c are located on the same axis along the third direction Z. The second branch channels 74 extend from the upstream side toward the junctions 71b and 71c. In detail, two second branch channels 74 adjacent to each other join each of the junctions 71b and 71c.

[0033] 2 and 3, the four second tributary channels 74 are independent of each other except at the junctions 71b and 71c. More specifically, the second tributary channels 74 are arranged in the third direction Z at intervals S2. The second tributary channels 74 have portions extending parallel to each other.

[0034] Each of the four grooves 37 has a wavy portion 70. The wavy portions 70 of the grooves 37 have the same shape. The wavy portions 70 in each groove 37 have portions that extend parallel to each other.

[0035] As shown in Figs. 2 to 4, the size of the interval S3 between the corrugated portions 70 is larger on the downstream side than on the upstream side. Specifically, the size of the interval S3 is larger on the downstream side. In this embodiment, between adjacent grooves 37, the size of the interval S3 between the first tributary 73 in one groove 37 and the first tributary 73 in the other groove 37 is the same as the size of the interval S1 in a portion where both first tributary 73 extend in parallel. Also, the size of the interval S3 between the second tributary 74 in one groove 37 and the second tributary 74 in the other groove 37 is the same as the size of the interval S2 in a portion where both second tributary 74 extend in parallel (see Fig. 3).

[0036] 5, each corrugated portion 70 is composed of a plurality of recesses 51 formed on the first surface 30A of the separator 30. Ribs 52 are provided between the recesses 51 as protrusions. The tips of the ribs 52 abut against the GDLs 12 of the MEA 10 adjacent to the separator 30.

[0037] 2, among the multiple grooves 37, the groove 37 located outermost in the third direction Z is defined as an outer groove 37A. The outer groove 37A has a portion located outer than the outer edge of the contact surface 30a in the third direction Z.

[0038] 1, the plurality of groove channels 38 are grooves that connect the through holes 33 and 34. The plurality of groove channels 38 are provided on the second surface 30B. In the groove channels 38, the cooling medium flows in the opposite direction to the fuel gas flowing through the groove channels 37.

[0039] As shown in FIG. 5, the groove 38 is provided on the surface 30b opposite to the contact surface 30a, and has a wavy portion 80 extending in a wavy manner in the surface direction of the surface 30b. Each wavy portion 80 is composed of a plurality of recesses 61 formed on the second surface 30B of the separator 30. Ribs 62 are provided between the recesses 61 as protrusions. The back side of the rib 62 is the recess 51 constituting the wavy portion 70 of the groove 37. Similarly, the back side of the rib 52 is the recess 61 constituting the wavy portion 80 of the groove 38. That is, the uneven shape forming the wavy portion 80 of the groove 38 is in an inseparable relationship with the uneven shape forming the wavy portion 70 of the groove 37.

[0040] <Separator 40> As shown in FIG. 1, the separator 40 has a rectangular plate shape that is elongated in the second direction Y when viewed from above. The separator 40 is formed by press-molding a metal member such as titanium or stainless steel.

[0041] The separator 40 is provided on the cathode electrode 11A side of the MEA 10. The separator 40 has a first surface 40A including a contact surface that contacts the MEA 10, and a second surface 40B opposite to the first surface 40A.

[0042] The separator 40 has through holes 41, 42, 43, 44, 45, and 46 which constitute holes 91, 92, 93, 94, 95, and 96. The through holes 41, 44, and 46 are provided at positions corresponding to the through holes 21, 24, and 26 of the frame member 20 in the third direction Z. The through holes 42, 43, and 45 are provided at positions corresponding to the through holes 22, 23, and 25 of the frame member 20 in the third direction Z.

[0043] As shown in Fig. 1, the separator 40 has a plurality of groove channels 47 through which the oxidant gas flows, and a plurality of groove channels 48 through which the coolant flows. Note that Fig. 1 shows a simplified view of the outer edge of the portion of the separator 40 where the plurality of groove channels 47 are formed, and the outer edge of the portion of the separator 40 where the plurality of groove channels 48 are formed.

[0044] The plurality of grooves 47 are grooves that connect the through holes 45 and the through holes 46. In the grooves 47, the oxidant gas flows in the opposite direction to the fuel gas flowing in the grooves 37. The plurality of groove channels 48 are grooves that connect the through holes 43 and the through holes 44. In the groove channels 48, the coolant flows in the same direction as the oxidant gas flowing through the groove channels 47.

[0045] Next, the operation of this embodiment will be described. 5 and 6, the flow of fuel gas flowing from the groove flow passage 37 into the GDL 12 is indicated by arrows.

[0046] As shown in FIG. 5, the fuel gas gradually penetrates into the MEA 10 adjacent to the separator 30, more specifically, into the GDL 12 constituting the MEA 10, while flowing through the groove 37 of the separator 30. Here, according to the configuration of this embodiment, as shown in FIG. 2, in the groove 37, the fuel gas flowing from the through hole 31 to the connection flow path 75 branches into four second branch paths 74 and flows downstream through the second branch paths 74. Then, the fuel gas flowing through the second branch paths 74 merges at each of the junctions 71b, 71c and flows into the first branch path 73. Then, the fuel gas flowing through the first branch path 73 merges at the junction 71a and flows into the main flow path 72. Here, the pressure loss of the fuel gas downstream of the junction 71a (71b, 71c) in the groove 37 is larger than the pressure loss of the fuel gas upstream of the junction 71a (71b, 71c). This promotes the infiltration of the fuel gas into the GDL 12 downstream of the junction 71a (71b, 71c) in the groove 37.

[0047] Next, the effects of this embodiment will be described. (1) The wavy portion 70 of the groove flow passage 37 extends in a wavy manner in the planar direction of the abutment surface 30a, and has a plurality of tributary flow passages 73 (74) and a junction portion 71a (71b, 71c) where the plurality of tributary flow passages 73 (74) join together from the upstream side to the downstream side.

[0048] This configuration provides the above-mentioned effects. Therefore, it is possible to suppress a decrease in the flow rate of the fuel gas that sneaks into the GDL 12 downstream of the groove flow passage 37. This also makes it possible to increase the amount of power generated downstream of the groove flow passage 37. This makes it possible to improve the power generation efficiency of the fuel cell.

[0049] Furthermore, with the above-described configuration, when the unit cells are stacked, the contact area between the ribs forming the grooves 47 of the separator 40 in one unit cell and the ribs 62 forming the grooves 37 of the separator 30 in the other unit cell is increased, thereby improving the stability of the contact structure between the adjacent separators 30, 40, and therefore the stability of the contact structure between the unit cells.

[0050] (2) The wavy portion 70 has confluences 71a, 71b, and 71c. With this configuration, the number of branch channels increases toward the upstream side in the wavy portion 70. Therefore, the pressure loss of the fuel gas increases toward the downstream side of the groove channels 37. As a result, the fuel gas is promoted to penetrate into the GDL 12 toward the downstream side where the flow rate of the fuel gas flowing through the groove channels 37 is smaller. Therefore, the decrease in the flow rate of the fuel gas penetrating into the GDL 12 can be effectively suppressed.

[0051] (3) The amplitude A of the wavy portion 70 on the downstream side is greater than the amplitude A on the upstream side. With this configuration, the pressure loss of the fuel gas downstream of the groove flow passage 37 is greater than the pressure loss of the fuel gas upstream. This promotes the infiltration of the fuel gas into the GDL 12 downstream of the groove flow passage 37 compared to when the amplitude A of the downstream side of the corrugated portion 70 is the same as the amplitude A of the upstream side. Therefore, the decrease in the flow rate of the fuel gas infiltrating into the GDL 12 can be more effectively suppressed.

[0052] (4) Each of the grooves 37 has a wavy portion 70 extending in a wavy manner in the surface direction of the contact surface 30a. Each of the wavy portions 70 has a plurality of branch passages 73, 74 and merging portions 71a, 71b, 71c. The size of the interval S3 between each of the wavy portions 70 increases toward the downstream side.

[0053] According to this configuration, the pressure loss of the fuel gas downstream of the confluences 71a, 71b, and 71c is greater than the pressure loss of the fuel gas upstream of the confluences 71a, 71b, and 71c in each of the groove channels 37. This further suppresses the decrease in the flow rate of the fuel gas entering the GDL 12 downstream of the groove channels 37.

[0054] In the grooves 47, the oxidant gas flows in the opposite direction to the fuel gas. Therefore, the MEA 10 is likely to become hot upstream of the grooves 47, i.e., downstream of the grooves 37. In this regard, according to the above-mentioned configuration, the size of the interval S3 between the corrugated portions 70 is larger toward the downstream side. Therefore, the flow rate of the cooling medium flowing through the grooves 38 increases downstream of the grooves 37, i.e., upstream of the grooves 38. This makes it possible to prevent the MEA 10 from becoming hot downstream of the grooves 37. Therefore, the power generation efficiency of the fuel cell can be further improved.

[0055] (5) In the groove 37, the first branch channels 73 that join at the joining portion 71a are independent of one another except at the joining portion 71a. In addition, the second branch channels 74 that join at the joining portions 71b and 71c in the groove 37 are independent of one another except at the joining portions 71b and 71c.

[0056] For example, when the second branch channels 74 are connected to each other, the flow pressure of the fuel gas flowing through each second branch channel 74 is uniformed at the connected portion. In this case, there is a risk that the difference between the pressure loss of the fuel gas in the second branch channel 74 and the pressure loss of the fuel gas downstream of the junctions 71b and 71c may become small. In this respect, according to the above configuration, the first branch channels 73 and the second branch channels 74 are independent of each other except for the junctions 71a, 71b, and 71c. Therefore, it is possible to suppress the difference between the pressure loss of the fuel gas upstream of the junctions 71a, 71b, and 71c and the pressure loss of the fuel gas downstream of the junctions 71a, 71b, and 71c from becoming small.

[0057] (6) The outer groove passage 37A, which is the groove passage 37 located outermost in the third direction Z, which is the arrangement direction of the groove passages 37, has a portion located outer than the outer edge of the abutment surface 30a in the third direction Z.

[0058] 6, when there is a difference in the pressure loss of the fuel gas between adjacent groove channels 37, a part of the fuel gas flowing through the groove channel 37 with the relatively large pressure loss may seep into the GDL 12 and flow to the groove channel 37 with the relatively small pressure loss. In this way, power generation is also performed by the fuel gas seeping into the portion of the GDL 12 located between the adjacent groove channels 37.

[0059] However, in the outer groove passage 37A, there is no groove passage 37 on the outside of the outer groove passage 37A in the third direction Z. Therefore, when the entire outer groove passage 37A is located inside the contact surface 30a in the third direction Z, the fuel gas is unlikely to enter the portion of the GDL 12 located outside the outer groove passage 37A by utilizing the difference in pressure loss of the fuel gas as described above. As a result, this is one of the factors that reduce the power generation efficiency.

[0060] In this regard, according to the above-mentioned configuration, the proportion of the portion of the GDL 12 located outside the outer groove passage 37A is reduced. This allows the fuel gas to penetrate into a wider area of ​​the GDL 12. Therefore, the power generation efficiency can be improved.

[0061] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0062] The shapes of the inlet holes 91, 93, 95 and the outlet holes 92, 94, 96 are not limited to the rectangular shape in plan view as exemplified in this embodiment. For example, the shapes of the inlet holes 91, 93, 95 and the outlet holes 92, 94, 96 may be square or elliptical in plan view.

[0063] The flow of the reactant gas in the holes 91, 92, 93, 94, 95, and 96 is not limited to that exemplified in this embodiment, and for example, the hole 96 may be an oxidant gas inlet hole and the hole 95 may be an oxidant gas outlet hole. Additionally, the hole 94 may be a coolant inlet hole and the hole 93 may be a coolant outlet hole. In other words, the oxidant gas flowing through the groove passage 47 and the coolant flowing through the groove passages 38 and 48 may flow in the same direction as the fuel gas flowing through the groove passage 37.

[0064] The number of grooves 37 is not limited to four as exemplified in this embodiment, but may be three or less, or five or more. The separator 30 is not limited to one in which each of the wavy portions 70 has the same shape as in the embodiment exemplified. For example, the wavelength and amplitude A of the wavy portions 70 may be changed for each groove 37 as appropriate.

[0065] The groove width of the groove 37, that is, the cross-sectional area of ​​the groove 37, does not have to be constant over the entire length of the groove 37 as long as the advantageous effects of the present invention are achieved. The groove 37 is not limited to the groove 37 having the outer groove 37A that is located outside the outer edge of the contact surface 30a in the third direction Z, as exemplified in this embodiment. For example, the outer groove 37A may be located at the same position as the outer edge of the contact surface 30a in the third direction Z, or may be located inside the outer edge.

[0066] The grooves 37 are not limited to those extending in a wavy manner in the surface direction of the contact surface 30a. In other words, all the grooves 37 do not have to have the wavy portions 70 extending in a wavy manner, and it is sufficient that at least one of the grooves 37 has the wavy portion 70.

[0067] The groove channels 37 are not limited to being independent of each other as illustrated in this embodiment, but may be, for example, adjacent groove channels 37 connected to each other by another groove channel extending in the third direction Z.

[0068] The two first branch channels 73 are not limited to being independent of each other except at the junction 71a as illustrated in this embodiment. For example, the first branch channels 73 may be connected to each other by another groove channel extending in the third direction Z.

[0069] The two second branch channels 74 are not limited to being independent of each other except at the junction 71b (71c) as illustrated in this embodiment. For example, the second branch channels 74 may be connected to each other by another groove channel extending in the third direction Z.

[0070] The wavy portion 70 is not limited to the one having a larger amplitude A on the downstream side as illustrated in this embodiment. For example, the amplitude A of the wavy portion 70 may be constant over the entire extension direction of the wavy portion 70.

[0071] In the present embodiment, the main flow channel 72 and the branch flow channels 73, 74 each have one wave number, but the shape of the wavy portion 70 is not limited to this. For example, as shown in Fig. 7, the wave number of the second branch flow channel 74 may be three, the wave number of the first branch flow channel 73 may be two, and the wave number of the main flow channel 72 may be one, so that the wave number may be gradually decreased toward the downstream side.

[0072] The connecting flow passage 75 may be omitted. In this case, the upstream end of each of the second branch flow passages 74 may be extended to the through hole 31. The number and arrangement of the junctions are not limited to those exemplified in this embodiment and may be changed as appropriate. Accordingly, the number and arrangement of the branch channels may also be changed as appropriate.

[0073] The separator for a fuel cell according to the present invention is not limited to the separator 30 joined to the anode electrode 11B side of the MEA 10 as exemplified in this embodiment, but can also be applied to a separator 40 joined to the cathode electrode 11A side.

[0074] The separators 30, 40 are not limited to those formed by press molding a metal member, but may also be formed by, for example, cutting or etching. The material used for the separators 30, 40 is not limited to titanium or stainless steel, but may also be aluminum or carbon. [Explanation of symbols]

[0075] A…Amplitude S1…Interval S2…Interval S3…Interval X…first direction Y: Second direction Z...Third direction 10...Membrane electrode assembly, MEA 11A…Cathode electrode 11B…Anode electrode 12...Gas diffusion layer, GDL 20...Frame member 21...Through hole 22...Through hole 23...Through hole 24...Through hole 25...Through hole 26...Through hole 27…Opening 30…Separator 30A…First side 30a…Abutting surface 30B…Second side 30b…side 31...Through hole 32...Through hole 33...Through hole 34...Through hole 35...Through hole 36…Through hole 37…Groove channel 37A…Outside groove channel 38…Groove channel 40…Separator 40A…Page 1 40B…Second side 41...Through hole 42...Through hole 43...Through hole 44…Through hole 45…Through hole 46…Through hole 47…Groove channel 48...Groove channel 51…Recess 52...Rib 61…Recess 62...Rib 70…Wavy part 71a… Junction 71b…merging part 71c…merging part 72...Main channel 73...1st tributary channel 74…Second tributary channel 75…Connecting channel 80…Wavy part 91...Inlet hole 92...Inlet hole 93...Inlet hole 94...Outlet hole 95...Outlet hole 96…Outlet hole

Claims

1. A separator for a fuel cell, comprising: a contact surface that contacts a power generation section of the fuel cell; and a plurality of groove channels through which a reactant gas flows are arranged in the contact surface, When the upstream side and the downstream side in the flow direction of the reaction gas in the groove flow passage are defined as the upstream side and the downstream side, the groove flow path extends in a wavy manner in a planar direction of the abutment surface, and has a plurality of branch flow paths and a junction portion where the plurality of branch flow paths join together from an upstream side to a downstream side, The number of the branch channels is greater on the upstream side, A flow path cross-sectional area of ​​each of the plurality of groove flow paths is constant throughout the extension direction of the groove flow path. A separator for fuel cells.

2. The groove flow path has a plurality of the junctions. The separator for a fuel cell according to claim 1 .

3. The amplitude of the downstream side of the groove flow channel is greater than the amplitude of the upstream side of the groove flow channel.

3. The separator for a fuel cell according to claim 1 or 2.

4. Each of the groove channels extends in a wavy manner in a surface direction of the contact surface, and has a plurality of the branch channels and the junction portion. The separator for a fuel cell according to any one of claims 1 to 3.

5. The plurality of branch channels that join at the joining portion in the groove channel are independent of each other except at the joining portion. The separator for a fuel cell according to any one of claims 1 to 4.

6. The outer groove channel, which is the groove channel positioned outermost in the arrangement direction of the groove channels, has a portion positioned at the same position as an outer edge of the contact surface or positioned outside the outer edge in the arrangement direction. The separator for a fuel cell according to any one of claims 1 to 5.

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