Separator for fuel cell

Abstract

To provide a separator for fuel cells capable of efficiently putting in a reaction gas over a wide range of a gas diffusion layer.SOLUTION: A separator 30 for fuel cells comprises an abutment surface 30a which is abutted to a MEA of a fuel cell and a plurality of groove channels 37 in which a fuel gas is circulated is provided side by side on the abutment surface 30a. The plurality of groove channels 37 includes a first groove channel 71 and a second groove channel 72 extending in a wavy state in a plane direction of the abutment surface 30a and being adjacent to each other in a third direction Z. The abutment surface 30a includes a rib 52 which is abutted to the MEA while being positioned between the first groove channel 71 and the second groove channel 72. The rib 52 includes a widened part 52a of which a width W in the third direction Z is enlarged in relative to the other portion in the rib 52. A channel cross-sectional area of a first adjacent part 75 adjacent with the widened part 52a in the first groove channel 71 is smaller than a channel cross-sectional area of a second adjacent part 76 adjacent with the widened part 52a in the second groove channel 72.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a single cell constituting a fuel cell stack. This single cell has a membrane electrode assembly (Membrane Electrode Assembly, hereinafter referred to as MEA), a first separator and a second separator sandwiching the MEA.

[0003] The MEA has a catalyst coated membrane (Catalyst Coated Membrane, hereinafter referred to as CCM) having an electrolyte membrane and a catalyst layer, and gas diffusion layers (Gas Diffusion Layer, hereinafter referred to as GDL) provided on both sides of the CCM, respectively.

[0004] The first separator has a plurality of first groove flow paths for an oxidizing gas and a plurality of cooling groove flow paths for a cooling medium. The first groove flow paths are linear and are formed on the surface of the first separator facing the MEA. The unevenness of the first groove flow paths and the unevenness of the cooling groove flow paths are in a front-back integrated relationship.

[0005] The second separator has a plurality of second groove flow paths for a fuel gas and a plurality of cooling groove flow paths for a cooling medium. The second groove flow paths are wavy and are formed on the surface of the second separator facing the MEA. The unevenness of the second groove flow paths and the unevenness of the cooling groove flow paths are in a front-back integrated relationship. The amplitude of the second groove flow paths is set to a size that overlaps with a plurality of convex portions constituting the back surfaces of the plurality of first groove flow paths in the first separator facing the second separator.

[0006] According to such a single cell, during the process of the oxidizing gas flowing through the first groove flow path of the first separator, it gradually penetrates into the GDL adjacent to the separator. Also, during the process of the fuel gas flowing through the second groove flow path of the second separator, it gradually penetrates into the GDL adjacent to the separator. In this way, power generation is performed by the oxidizing gas and the fuel gas that have penetrated into the GDL respectively undergoing an electrochemical reaction in the CCM.

[0007] Also, according to such a single cell, when stacking the single cells, the contact portion between the convex portion constituting the second groove flow path in one single cell and the convex portion constituting the back surface of the first groove flow path in the other single cell increases. Therefore, the stability of the contact structure between adjacent separators, and thus the stability of the contact structure between single cells, is improved.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] By the way, in such a single cell, in order to improve the power generation efficiency, it is desired to efficiently allow the fuel gas to penetrate into a wider range of the GDL. Note that such problems are not limited to the separator having a groove flow path for fuel gas, and the same problems also occur in the separator having a groove flow path for oxidizing gas.

[0010] An object of the present invention is to provide a separator for a fuel cell that can efficiently allow a reaction gas to penetrate into a wide range of a gas diffusion layer.

Means for Solving the Problems

[0011] A separator for a fuel cell to achieve the above object has an abutment surface that abuts on 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, when the direction in which the groove channels are arranged is defined as an arrangement direction, the plurality of groove channels include first groove channels and second groove channels that respectively extend in a wavy manner in a plane direction of the abutment surface and are adjacent to each other in the arrangement direction, the abutment surface has a rib that is located between the first groove channel and the second groove channel and abuts on the power generation unit, the rib has a widened portion that is wider in the arrangement direction than other portions of the rib, and a flow path cross-sectional area of a first adjacent portion adjacent to the widened portion in the first groove channel is smaller than a flow path cross-sectional area of a second adjacent portion adjacent to the widened portion in the second groove channel.

[0012] In the groove flow passage, the pressure loss of the reactant gas flowing through a portion having a small flow passage cross-sectional area is larger than that of a portion having a large flow passage cross-sectional area. According to the above configuration, a difference occurs in the pressure loss of the reactant gas between the first adjacent portion and the second adjacent portion. Therefore, a part of the reactant gas flowing through the first adjacent portion, which has a relatively large pressure loss, penetrates into the gas diffusion layer and flows toward the second adjacent portion, which has a relatively small pressure loss. This allows the reactant gas to penetrate into the portion of the gas diffusion layer where the widened portion abuts, i.e., the portion where the reactant gas is likely to be insufficient because the gap between the groove channels is wider than in other portions.

[0013] Therefore, the reactant gas can efficiently penetrate into a wide area of the gas diffusion layer. [Brief description of the drawings]

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

[0015] 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.

[0016] 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.

[0017] Further, the description will be given assuming that the second direction Y is the longitudinal direction of the unit cell and is perpendicular to the first direction X. Also, a direction orthogonal to both the first direction X and the second direction Y will be described as the third direction Z.

[0018] The single cell has introduction holes 91, 93, 95 for introducing a reaction gas or a cooling medium into the single cell, and discharge holes 92, 94, 96 for discharging the reaction gas and the cooling medium in the single cell to the outside. In the present embodiment, the introduction hole 91 and the discharge hole 92 are holes through which the fuel gas flows. Also, the introduction hole 93 and the discharge hole 94 are holes through which the cooling medium flows. Further, the introduction hole 95 and the discharge hole 96 are holes through which the oxidant gas flows. Here, the fuel gas is hydrogen gas. Also, the cooling medium is cooling water. Further, the oxidant gas is air.

[0019] The introduction holes 91, 93, 95 and the discharge holes 92, 94, 96 are rectangular in plan view and long in the second direction Y, and penetrate the single cell in the first direction X. The introduction hole 91 and the discharge holes 94, 96 are provided on one side of the single cell in the second direction Y (the left side in the left - right direction of FIG. 1). The introduction hole 91 and the discharge holes 94, 96 are arranged at intervals in the third direction Z. The discharge hole 92 and the introduction holes 93, 95 are provided on the other side of the single cell in the second direction Y (the right side of FIG. 1). The discharge hole 92 and the introduction holes 93, 95 are arranged at intervals in the third direction Z.

[0020] <mea10> As shown in FIG. 1, the MEA 10 has a rectangular shape in plan view that is long in the second direction Y. The MEA 10 has a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane), which is not shown, and electrode 11A and 11B provided on both surfaces of the electrolyte membrane. In this embodiment, the electrode joined to one side (the 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. Also, the electrode joined to the other side (the lower side in FIG. 1) of the electrolyte membrane in the first direction X is the anode electrode 11B.

[0021] The electrodes 11A and 11B have a catalyst layer (not shown) joined to the electrolyte membrane and a gas diffusion layer 12 (hereinafter referred to as GDL 12) joined to the catalyst layer. Note that the MEA 10 corresponds to the power generation part of the fuel cell according to the present invention.

[0022] <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 formed of, for example, a hard resin material.

[0023] The frame member 20 has through holes 21, 22, 23, 24, 25, and 26 that constitute holes 91, 92, 93, 94, 95, and 96. The frame member 20 has an opening 27 that is rectangular in plan view and long in the second direction Y at the center. The MEA 10 is joined to the edge of the opening 27 from one side (the upper side in FIG. 1) in the first direction X.

[0024] <Separator 30> As shown in FIG. 1, the separator 30 has a rectangular plate shape in plan view that is long in the second direction Y. The separator 30 is formed, for example, by press-molding a metal member such as titanium or stainless steel.

[0025] 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.

[0026] The separator 30 has through holes 31, 32, 33, 34, 35, 36 that form holes 91, 92, 93, 94, 95, 96. The through holes 31, 34, 36 are provided at positions corresponding to the through holes 21, 24, 26 of the frame member 20 in the third direction Z, respectively. Further, the through holes 32, 33, 35 are provided at positions corresponding to the through holes 22, 23, 25 of the frame member 20 in the third direction Z, respectively.

[0027] The separator 30 has a plurality of groove flow paths 37 through which fuel gas flows, and a plurality of groove flow paths 38 through which a cooling medium flows. In FIG. 1, the outer edges of the portions where the plurality of groove flow paths 37 are formed and the outer edges of the portions where the plurality of groove flow paths 38 are formed in the separator 30 are shown in a simplified manner.

[0028] <Groove flow paths 37, 38> As shown in FIG. 2, the plurality of groove flow paths 37 are grooves that communicate the through hole 31 and the through hole 32, and are provided on the first surface 30A. In the present embodiment, six groove flow paths 37 are arranged at intervals in the third direction Z. That is, each of the six groove flow paths 37 is independent of each other.

[0029] Hereinafter, the upstream side and the downstream side in the flow direction of the fuel gas in the groove flow path 37 will be simply described as the upstream side and the downstream side. Here, the upstream side in the above flow direction corresponds to one side in the second direction Y (the left side in the left-right direction of FIG. 2). Further, the downstream side in the above flow direction corresponds to the other side in the second direction Y (the right side in the figure).

[0030] The groove width of the groove flow path 37 is constant over the entire extending direction of the groove flow path 37. The groove widths of the respective groove flow paths 37 are the same as each other. The six groove channels 37 are composed of three first groove channels 71 and three second groove channels 72. The first groove channels 71 and the second groove channels 72 are alternately provided in the third direction Z.

[0031] The first groove channel 71 is provided on the contact surface 30a and has a corrugated portion 73 that extends in a wavy shape in the plane direction of the contact surface 30a. In this embodiment, the corrugated portion 73 is a so-called sine wave, and the wavelength λ and the amplitude A are constant over the entire extending direction of the corrugated portion 73. Also, the number of waves of the corrugated portion 73 is three.

[0032] The second groove channel 72 is provided on the contact surface 30a and has a corrugated portion 74 that extends in a wavy shape in the plane direction of the contact surface 30a. In this embodiment, the corrugated portion 74 has the same waveform as the corrugated portion 73.

[0033] As shown in FIGS. 3 to 5, each of the groove channels 71, 72 is constituted by a plurality of recesses 51 formed in the first surface 30A of the separator 30. Between the recesses 51 adjacent to each other in the third direction Z, ribs 52 are provided as convex portions. The tip ends of the respective ribs 52 are portions that contact the GDL 12 of the MEA 10 adjacent to the separator 30 (see FIGS. 9 and 10).

[0034] As shown in FIG. 2, in the portion located between the corrugated portion 73 and the corrugated portion 74, the rib 52 has a widened portion 52a. The widened portion 52a has a larger width W in the third direction Z than other portions of the rib 52 in the portion located between the corrugated portion 73 and the corrugated portion 74. Each rib 52 has three widened portions 52a in the extending direction of the rib 52. In this embodiment, the widened portion 52a is located between portions including the apexes V1, V2 of the corrugated portion 73 and the corrugated portion 74, respectively.

[0035] As shown in FIGS. 2 to 5, the wavy portion 73 of each first groove channel 71 has two first adjacent portions 75 adjacent to the widened portion 52a in the third direction Z and one third adjacent portion 77. The first adjacent portions 75 and the third adjacent portion 77 are alternately provided in the extending direction of the wavy portion 73. That is, one third adjacent portion 77 is located between the first adjacent portions 75 (see FIG. 2).

[0036] As shown in FIGS. 6 to 8, the depth D3 of the portion constituting the first adjacent portion 75 in the recess 51 is smaller than the depth D1 of the recess 51 constituting the portion other than the adjacent portions 75 and 77 in the first groove channel 71 (hereinafter referred to as the general portion 71a) (D3 < D1). That is, the flow path cross-sectional area of the first adjacent portion 75 is smaller than the flow path cross-sectional area of the general portion 71a. In this embodiment, the depth D1 of the general portion 71a, that is, the flow path cross-sectional area, is constant throughout the extending direction of the general portion 71a.

[0037] The first adjacent portion 75 has an upstream-side gradually changing portion 75a with a larger depth D3 toward the upstream side and a downstream-side gradually changing portion 75c with a larger depth D3 toward the downstream side. Further, the first adjacent portion 75 has an intermediate portion 75b located between the upstream-side gradually changing portion 75a and the downstream-side gradually changing portion 75c. The depth D3 of the intermediate portion 75b is constant throughout the extending direction of the intermediate portion 75b. The depth D3 of the intermediate portion 75b is the minimum value of the depth D3 of each first adjacent portion 75.

[0038] As shown in FIGS. 3 and 5, in each first groove channel 71, the minimum value of the depth D3 of the portion constituting the first adjacent portion 75 in the recess 51 is smaller for the first adjacent portion 75 located on the downstream side. That is, in each first groove channel 71, the minimum value of the flow path cross-sectional area of the first adjacent portion 75 is smaller for the first adjacent portion 75 located on the downstream side.

[0039] As shown in FIG. 4, the depth of the portion constituting the third adjacent portion 77 in the recess 51 is the same as the depth D1 of the recess 51 constituting the general portion 71a. That is, the flow path cross-sectional area of the third adjacent portion 77 is the same as the flow path cross-sectional area of the general portion 71a.

[0040] As shown in FIGS. 2 to 5, the wavy portion 74 of each second groove channel 72 has two second adjacent portions 76 adjacent to the widened portion 52a in the third direction Z and one fourth adjacent portion 78. The second adjacent portions 76 and the fourth adjacent portion 78 are alternately provided in the extending direction of the wavy portion 74. That is, one fourth adjacent portion 78 is located between the second adjacent portions 76 (see FIG. 2).

[0041] The depth of the portion of the recess 51 that constitutes the second adjacent portion 76 is the same as the depth D2 of the recess 51 that constitutes the portion other than the adjacent portions 76 and 78 in the second groove channel 72 (hereinafter, the general portion 72a). That is, the flow path cross-sectional area of the second adjacent portion 76 is the same as the flow path cross-sectional area of the general portion 72a. In the present embodiment, the depth D2 of the general portion 72a, that is, the flow path cross-sectional area, is constant throughout the extending direction of the general portion 72a.

[0042] Here, the depth D2 is the same as the depth D1 (D2 = D1, see FIG. 9). That is, the flow path cross-sectional areas of the general portion 72a and the second adjacent portion 76 are the same as the flow path cross-sectional areas of the general portion 71a and the third adjacent portion 77 of the first groove channel 71.

[0043] Also, the depth D3 is smaller than the depth D2 (D3 < D2, see FIGS. 3 and 5). That is, the flow path cross-sectional area of the first adjacent portion 75 is smaller than the flow path cross-sectional area of the second adjacent portion 76. The depth D4 of the portion of the recess 51 that constitutes the fourth adjacent portion 78 is smaller than the depth D2 of the recess 51 that constitutes the general portion 72a (D4 < D2). That is, the flow path cross-sectional area of the fourth adjacent portion 78 is smaller than the flow path cross-sectional area of the general portion 72a. In the present embodiment, the depth D4 is smaller than the depth D1 (D4 < D1, see FIG. 4). That is, the flow path cross-sectional area of the fourth adjacent portion 78 is smaller than the flow path cross-sectional area of the third adjacent portion 77.

[0044] As shown in FIG. 2, among the plurality of groove channels 37, the groove channel 37 located most outside in the third direction Z is defined as the outer groove channel 37A. The outer groove channel 37A has a portion located outside the outer edge of the contact surface 30a in the third direction Z.

[0045] As shown in FIG. 1, the plurality of groove channels 38 are grooves that communicate the through hole 33 and the through hole 34. The plurality of groove channels 38 are provided on the second surface 30B. In the groove channels 38, the cooling medium flows in a direction opposite to the fuel gas flowing through the groove channel 37.

[0046] As shown in FIGS. 3 to 5, the groove channel 38 is provided on the surface 30b on the opposite side of the contact surface 30a and has a corrugated portion 38a that extends in a wavy shape in the surface direction of the surface 30b. Each corrugated portion 38a is constituted by a plurality of recesses 61 formed in the second surface 30B of the separator 30. Between the recesses 61, ribs 62 are provided as convex portions. The back side of the rib 62 is a recess 51 that constitutes the corrugated portions 73 and 74 of the groove channel 37. Similarly, the back side of the rib 52 is a recess 61 that constitutes the corrugated portion 38a of the groove channel 38. That is, the concavo-convex shape forming the corrugated portion 38a of the groove channel 38 is in a relationship of front and back integration with the concavo-convex shape forming the corrugated portions 73 and 74 of the groove channel 37.

[0047] <Separator 40> As shown in FIG. 1, the separator 40 is a rectangular plate-like shape in plan view that is long in the second direction Y. The separator 40 is formed, for example, by press-molding a metal member such as titanium or stainless steel.

[0048] 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 that is opposite to the first surface 40A.

[0049] The separator 40 has through holes 41, 42, 43, 44, 45, 46 that constitute holes 91, 92, 93, 94, 95, 96. The through holes 41, 44, 46 are provided at positions corresponding to the through holes 21, 24, 26 of the frame member 20 in the third direction Z, respectively. Further, the through holes 42, 43, 45 are provided at positions corresponding to the through holes 22, 23, 25 of the frame member 20 in the third direction Z, respectively.

[0050] 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.

[0051] 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.

[0052] Next, the operation of this embodiment will be described. 9 and 10, the flow of fuel gas entering the GDL 12 from the groove flow passage 37 is indicated by arrows.

[0053] As shown in FIG. 9, while the fuel gas flows through the groove channels 37 of the separator 30, it gradually seeps into the MEA 10 adjacent to the separator 30, more specifically, into the GDL 12 constituting the MEA 10.

[0054] As shown in FIG. 10, in the groove flow passage 37, the pressure loss of the fuel gas flowing through the portion having a small flow passage cross-sectional area is larger than that of the portion having a large flow passage cross-sectional area. According to the configuration of this embodiment, a difference occurs in the magnitude of pressure loss of the fuel gas between the first adjacent portion 75 of the first groove flow passage 71 and the second adjacent portion 76 of the second groove flow passage 72. Therefore, a part of the fuel gas flowing through the first adjacent portion 75, which has a relatively large pressure loss, enters the GDL 12 and flows toward the second adjacent portion 76, which has a relatively small pressure loss.

[0055] Although not shown, a difference occurs in the magnitude of pressure loss of the fuel gas between the third adjacent portion 77 of the first groove flow passage 71 and the fourth adjacent portion 78 of the second groove flow passage 72. As a result, a part of the fuel gas flowing through the fourth adjacent portion 78, which has a relatively large pressure loss between the third adjacent portion 77 and the fourth adjacent portion 78, enters the GDL 12 and flows toward the third adjacent portion 77, which has a relatively small pressure loss.

[0056] Next, the effects of this embodiment will be described. (1) The groove channels 37 each have wavy portions 73, 74 extending in a wavy manner in the surface direction of the contact surface 30a, and each have a first groove channel 71 and a second groove channel 72 adjacent to each other in the third direction Z. The contact surface 30a has a rib 52 located between the first groove channel 71 and the second groove channel 72 and in contact with the GDL 12 of the MEA 10. In a portion located between the wavy portion 73 and the wavy portion 74, the rib 52 has a widened portion 52a having a larger width W in the third direction Z than other portions of the rib 52. The flow path cross-sectional area of a first adjacent portion 75 adjacent to the widened portion 52a in the wavy portion 73 of the first groove channel 71 is smaller than the flow path cross-sectional area of a second adjacent portion 76 adjacent to the widened portion 52a in the wavy portion 74 of the second groove channel 72.

[0057] This configuration provides the above-mentioned effect, and allows the fuel gas to flow into the portion of the GDL 12 that is in contact with the widened portion 52a, i.e., the portion where the fuel gas is likely to be insufficient because the gap between the groove channels 71, 72 is wider than in other portions.

[0058] Therefore, the fuel gas can efficiently permeate a wide area of the GDL 12. (2) The first adjacent portion 75 has an upstream gradually changing portion 75a whose flow path cross-sectional area increases toward the upstream side, a downstream gradually changing portion 75c whose flow path cross-sectional area increases toward the downstream side, and an intermediate portion 75b located between the upstream gradually changing portion 75a and the downstream gradually changing portion 75c. The flow path cross-sectional area of the intermediate portion 75b is constant in the extension direction of the intermediate portion 75b.

[0059] According to such a configuration, in the first groove flow path 71, a portion upstream of the first adjacent portion 75 and the intermediate portion 75b are connected by the upstream-side gradual change portion 75a. Also, in the first groove flow path 71, a portion downstream of the first adjacent portion 75 and the intermediate portion 75b are connected by the downstream-side gradual change portion 75c. Thereby, it is possible to suppress a sudden increase in the pressure loss of the fuel gas when flowing into or out of the first adjacent portion 75. Therefore, while increasing the pressure loss in the first adjacent portion 75, it is possible to suppress a decrease in the flow velocity of the fuel gas flowing through the first adjacent portion 75.

[0060] (3) The rib 52 has a plurality of widened portions 52a in the extending direction of the rib 52. The corrugated portion 73 of the first groove flow path 71 has a plurality of first adjacent portions 75. The corrugated portion 74 of the second groove flow path 72 has a plurality of second adjacent portions 76. The flow path cross-sectional area of each of the first adjacent portions 75 is smaller than the flow path cross-sectional area of the second adjacent portion 76 adjacent to the first adjacent portion 75 with the widened portion 52a interposed therebetween.

[0061] According to such a configuration, the operational effects according to (1) can be exhibited at a plurality of locations in the flow direction of the fuel gas. Therefore, the fuel gas can efficiently penetrate into a wider range of the GDL12.

[0062] (4) The minimum value of the flow path cross-sectional area of the first adjacent portion 75 is smaller for the first adjacent portion 75 located downstream. According to such a configuration, the pressure loss of the fuel gas becomes larger for the first adjacent portion 75 located downstream. Thereby, the penetration of the fuel gas into the GDL12 is promoted more on the downstream side where the flow rate of the fuel gas flowing through the first groove flow path 71 decreases. Therefore, it is possible to effectively suppress a decrease in the flow rate of the fuel gas penetrating into the GDL12.

[0063] (5) The corrugated portion 73 of the first groove flow path 71 has a third adjacent portion 77 adjacent to the widened portion 52a. The corrugated portion 74 of the second groove flow path 72 has a fourth adjacent portion 78 adjacent to the third adjacent portion 77 with the widened portion 52a interposed therebetween in the third direction Z. The flow path cross-sectional area of the fourth adjacent portion 78 is smaller than the flow path cross-sectional area of the third adjacent portion 77.

[0064] For example, when the first adjacent portion 75 and the second adjacent portion 76 are adjacent to each of the widened portions 52a, the following problem may occur. That is, the fuel gas flowing through the first groove passage 71 flows into the second groove passage 72 via the GDL 12 over the entire extension direction of the first groove passage 71. Therefore, in the first groove passage 71, the flow rate of the fuel gas that sneaks into the GDL 12 on the downstream side in the flow direction of the fuel gas is reduced. This may result in a reduction in the amount of power generation on the downstream side.

[0065] In this regard, according to the above configuration, the fuel gas flowing through the fourth adjacent portion 78 flows to the third adjacent portion 77 via the GDL 12. This prevents the flow of fuel gas flowing from the groove flow passage into the GDL 12 from being biased toward the first groove flow passage 71. Therefore, a decrease in the flow rate of fuel gas flowing into the GDL 12 downstream of the first groove flow passage 71 can be prevented.

[0066] (6) The first adjacent portions 75 and the third adjacent portions 77 are provided alternately in the extension direction of the wavy portion 73. The second adjacent portions 76 and the fourth adjacent portions 78 are provided alternately in the extension direction of the wavy portion 74.

[0067] With this configuration, the flow rate of the fuel gas flowing from the first groove passage 71 into the GDL 12 and the flow rate of the fuel gas flowing from the second groove passage 72 into the GDL 12 in the fuel gas flow direction are uniform. Therefore, a decrease in the flow rate of the fuel gas flowing into the GDL 12 downstream of the groove passage 37 can be suppressed.

[0068] (7) The first groove flow passage 71 and the second groove flow passage 72 are independent of each other. For example, when the first groove passage 71 and the second groove passage 72 are connected to each other, the flow pressure of the fuel gas flowing through each of the groove passages 71 and 72 is uniformed at the connected portion. Therefore, it is difficult to adjust the pressure loss of the fuel gas by making the flow passage cross-sectional areas of the first groove passage 71 and the second groove passage 72 different.

[0069] In this regard, according to the above configuration, the first groove flow path 71 and the second groove flow path 72 are independent of each other. Therefore, it is easy to adjust the pressure loss of the fuel gas in the first groove flow path 71 and the second groove flow path 72.

[0070] (8) The plurality of groove flow paths 37 are composed of a plurality of first groove flow paths 71 and a plurality of second groove flow paths 72. The first groove flow paths 71 and the second groove flow paths 72 are alternately provided in the third direction Z.

[0071] According to such a configuration, the operational effects according to (1) can be exhibited in all the groove flow paths 37. Therefore, the fuel gas can efficiently penetrate into a wider range of the GDL 12.

[0072] (9) The outer groove flow path 37A, which is the groove flow path 37 located most outward in the third direction Z, has a portion located outside the outer edge of the contact surface 30a in the third direction Z. In the outer groove flow path 37A, there is no groove flow path 37 outside itself in the third direction Z. Therefore, when the entire outer groove flow path 37A is located inside the contact surface 30a in the third direction Z, it is difficult for the fuel gas to penetrate into the portion of the GDL 12 located outside the outer groove flow path 37A by utilizing the difference in the pressure loss of the fuel gas as described above. As a result, this contributes to a decrease in the power generation efficiency.

[0073] In this regard, according to the above configuration, the ratio of the portion of the GDL 12 located outside the outer groove flow path 37A decreases. Thereby, the fuel gas can penetrate into a wider range of the GDL 12. Therefore, the power generation efficiency can be improved.

[0074] <Modified Example> This embodiment can be implemented by making the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0075] · The shapes of the introduction holes 91, 93, 95 and the discharge holes 92, 94, 96 are not limited to the rectangular shape in plan view as illustrated in this embodiment. For example, the shapes of the introduction holes 91, 93, 95 and the discharge holes 92, 94, 96 may be square or oval in plan view.

[0076] · The flow of the reaction gas through the holes 91, 92, 93, 94, 95, 96 is not limited to that illustrated in this embodiment. For example, hole 96 may be used as the introduction hole for the oxidant gas, and hole 95 may be used as the discharge hole for the oxidant gas. Accordingly, hole 94 may be used as the introduction hole for the cooling medium, and hole 93 may be used as the discharge hole for the cooling medium. That is, the oxidant gas flowing through the groove channel 47 and the cooling medium flowing through the groove channels 38, 48 may flow in the same direction as the fuel gas flowing through the groove channel 37.

[0077] · The number of the groove channels 37 is not limited to six as illustrated in this embodiment, and may be five or less or seven or more. · The groove channel 37 is not limited to having a portion where the outer groove channel 37A is located outside the outer edge of the contact surface 30a in the third direction Z as illustrated in this embodiment. For example, the outer groove channel 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.

[0078] · The plurality of groove channels 37 are not limited to being composed of a plurality of first groove channels 71 and a plurality of second groove channels 72. For example, the plurality of groove channels 37 may have at least one first groove channel 71 and at least one second groove channel 72 adjacent to each other, and may have groove channels different from the first groove channels 71 and the second groove channels 72.

[0079] · The first groove channel 71 and the second groove channel 72 are not limited to being independent of each other as illustrated in this embodiment. For example, the first groove channel 71 and the second groove channel 72 may be communicated with each other by another groove channel extending in the third direction Z.

[0080] · The first groove flow path 71 is not limited to the case where the first adjacent part 75 and the third adjacent part 77 are alternately provided as illustrated in this embodiment, and the arrangement of the adjacent parts 75 and 77 may be changed as appropriate. For example, the first groove flow path 71 can be changed so that the first adjacent parts 75 are arranged continuously. In this case, the second adjacent part 76 may be provided at a position corresponding to the first adjacent part 75 in the second groove flow path 72.

[0081] · The number of the third adjacent parts 77 is not limited to one as illustrated in this embodiment, and two or more of them may be provided. Accordingly, the number of the fourth adjacent parts 78 may also be changed as appropriate. Further, the third adjacent part 77 and the fourth adjacent part 78 can also be omitted. In this case, the first adjacent part 75 and the second adjacent part 76 may be provided corresponding to each of the plurality of widened parts 52a.

[0082] · The minimum value of the flow path cross-sectional area of the first adjacent part 75 does not have to be smaller for the first adjacent part 75 located on the downstream side as illustrated in this embodiment. For example, the minimum value of the flow path cross-sectional area of the first adjacent part 75 may be the same for each first adjacent part 75, or may be larger for the first adjacent part 75 located on the upstream side.

[0083] · The downstream gradual change part 75c may be omitted from the first adjacent part 75. In this case, the part on the downstream side of the first adjacent part 75 and the intermediate part 75b in the first groove flow path 71 may be directly connected.

[0084] · The upstream gradual change part 75a may be omitted from the first adjacent part 75. In this case, the part on the upstream side of the first adjacent part 75 and the intermediate part 75b in the first groove flow path 71 may be directly connected.

[0085] In order to make the flow path cross-sectional area of the first adjacent portion 75 smaller than that of the second adjacent portion 76, for example, the first adjacent portion 75 may be modified as follows. That is, as shown in FIG. 11, the groove width W1 of the portion of the recess 51 that constitutes the first adjacent portion 75 may be made smaller than the groove width W2 of the recess 51 that constitutes the second adjacent portion 76 (W1 <W2)。この場合、第1隣接部75の深さD3は、第1溝流路71の他の部分の深さD1及び第2溝流路72の深さD2と同一であってもよいし(D3=D1,D2、図11参照)、深さD1,D2よりも小さくてもよい(D3<D1,D2)。

[0086] The first groove 71 and the second groove 72 are not limited to those in which the flow path cross-sectional areas of the general portions 71a and 72a are constant throughout the entire extension direction of each of them as illustrated in this embodiment. For example, a portion where the flow path cross-sectional area is smaller may be provided midway in the extension direction of either one of the general portions 71a and 72a. Also, a portion where the flow path cross-sectional area is smaller may be provided midway in the extension direction of both of the general portions 71a and 72a. In this case, it is sufficient that the above-mentioned portion of the general portion 71a and the above-mentioned portion of the general portion 72a are not adjacent to each other in the third direction Z.

[0087] With this configuration, a difference occurs in the magnitude of pressure loss of the fuel gas between the general portion 71a of the first groove flow passage 71 and the general portion 72a of the second groove flow passage 72. Therefore, a part of the fuel gas flowing through the general portion 71a or the general portion 72a, whichever has a relatively larger pressure loss, permeates the GDL 12 and flows toward the portion with a relatively smaller pressure loss. This allows the fuel gas to permeate a wider range of the GDL 12.

[0088] The first groove flow passage 71 is not limited to the first adjacent portion 75 having a flow passage cross-sectional area smaller than the flow passage cross-sectional area of the second adjacent portion 76 adjacent to the first adjacent portion 75 with the widened portion 52a interposed therebetween, as exemplified in this embodiment. That is, the first groove flow passage 71 may have at least one of the first adjacent portions 75 having a flow passage cross-sectional area smaller than the flow passage cross-sectional area of the second adjacent portion 76 adjacent to the first adjacent portion 75 with the widened portion 52a interposed therebetween.

[0089] · The shapes of the first groove flow path 71 and the second groove flow path 72 are not limited to the shapes exemplified in the present embodiment, and may be changed as appropriate. For example, if the rib 52 located between the first groove flow path 71 and the second groove flow path 72 has at least one widened portion 52a in the flow direction of the fuel gas, the wavelength λ, amplitude A, and wave number of the corrugated portions 73 and 74 may be changed as appropriate. In this case, the widened portion 52a does not necessarily have to be located between the portions including the vertices V1 and V2 of the corrugated portions 73 and 74 as exemplified in the present embodiment.

[0090] · 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 the present embodiment, and can also be applied to the separator 40 joined to the cathode electrode 11A side.

[0091] · The separators 30 and 40 are not limited to those formed by press-molding a metal member, and can also be formed, for example, by cutting or etching. · The materials used for the separators 30 and 40 are not limited to titanium or stainless steel, and aluminum or carbon can also be used.

Explanation of Reference Numerals

[0092] λ... Wavelength A... Amplitude D1, D2, D3, D4... Depth V1, V2... Vertices W... Width W1, W2... Groove Width 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 surface 30a…Contact surface 30B…Second surface 30b…Surface 31…Through hole 32…Through hole 33…Through hole 34…Through hole 35…Through hole 36…Through hole 37…Groove flow path 37A…Outer groove flow path 38…Groove flow path 38a…Wave portion 40…Separator 40A…First surface 40B…Second surface 41…Through hole 42…Through hole 43…Through hole 44…Through hole 45…Through hole 46…Through hole 47…Groove flow path 48…Groove flow path 51…Recess 52…Rib 52a…Width expansion portion 61…Recess 62…Rib 71…First groove flow path 71a…General portion 72…Second groove flow path 72a…General portion 73…Wave portion 74…Wave portion 75…First adjacent portion 75a…Upstream side gradual change portion 75b…Middle portion 75c…Downstream side gradual change portion 76…Second adjacent portion 77…Third adjacent portion 78…Fourth adjacent portion 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, having a contact surface that contacts a power generation part of the fuel cell, and a plurality of groove channels through which a reaction gas flows are provided side by side on the contact surface, when the direction in which the groove channels are arranged is defined as the arrangement direction, and the direction in which the reaction gas flows in the groove channels is defined as the flow direction, the plurality of groove channels include a first groove channel and a second groove channel that each extend in a wavy shape in the plane direction of the contact surface and are adjacent to each other in the arrangement direction, the contact surface has a rib that is located between the first groove channel and the second groove channel and contacts the power generation part, the rib has a widened portion with a larger width in the arrangement direction than other portions of the rib in the flow direction, a cross-sectional area of a flow path of a first adjacent portion adjacent to the widened portion in the first groove channel is smaller than a cross-sectional area of a flow path of a second adjacent portion adjacent to the widened portion in the second groove channel, an outer groove channel, which is the groove channel located most outward in the arrangement direction, has a portion located outside the outer edge of the contact surface in the arrangement direction, A separator for a fuel cell.

2. A separator for a fuel cell, having a contact surface that contacts a power generation part of the fuel cell, and a plurality of groove channels through which a reaction gas flows are provided side by side on the contact surface, when the direction in which the groove channels are arranged is defined as the arrangement direction, and the direction in which the reaction gas flows in the groove channels is defined as the flow direction, the plurality of groove channels include a first groove channel and a second groove channel that each extend in a wavy shape of a sine wave having the same waveform in the plane direction of the contact surface and are adjacent to each other in the arrangement direction, the contact surface has a rib that is located between the first groove channel and the second groove channel and contacts the power generation part, the rib has a widened portion with a larger width in the arrangement direction than other portions of the rib in the flow direction, a cross-sectional area of a flow path of a first adjacent portion adjacent to the widened portion in the first groove channel is smaller than a cross-sectional area of a flow path of a second adjacent portion adjacent to the widened portion in the second groove channel, A separator for a fuel cell.

3. when the upstream side and the downstream side in the flow direction in the groove channels are defined as the upstream side and the downstream side, The first adjacent part has an upstream gradually changing part with a larger flow path cross-sectional area toward the upstream side, a downstream gradually changing part with a larger flow path cross-sectional area toward the downstream side, and an intermediate part located between the upstream gradually changing part and the downstream gradually changing part and having a constant flow path cross-sectional area in the flow direction. The separator for a fuel cell according to claim 1 or claim 2.

4. The rib has a plurality of the widening parts in the flow direction. The first groove flow path has a plurality of the first adjacent parts in the flow direction. The second groove flow path has a plurality of the second adjacent parts in the flow direction. The flow path cross-sectional area of each of the first adjacent parts is smaller than the flow path cross-sectional area of the second adjacent part adjacent to the first adjacent part with the widening part therebetween. The separator for a fuel cell according to any one of claims 1 to 3.

5. The minimum value of the flow path cross-sectional area of the first adjacent part is smaller for the first adjacent part located downstream. The separator for a fuel cell according to claim 4.

6. The rib has a plurality of the widening parts in the flow direction. The first groove flow path has a third adjacent part adjacent to the widening part. The second groove flow path has a fourth adjacent part adjacent to the third adjacent part with the widening part therebetween in the arrangement direction. The flow path cross-sectional area of the fourth adjacent part is smaller than the flow path cross-sectional area of the third adjacent part. The separator for a fuel cell according to any one of claims 1 to 5.

7. The first adjacent part and the third adjacent part are provided alternately in the flow direction. The second adjacent part and the fourth adjacent part are provided alternately in the flow direction. The separator for a fuel cell according to claim 6.

8. The first groove flow path and the second groove flow path are independent of each other. The separator for a fuel cell according to any one of claims 1 to 7.

9. The plurality of groove flow paths are composed of a plurality of the first groove flow paths and a plurality of the second groove flow paths. The first groove flow path and the second groove flow path are provided alternately in the arrangement direction. The separator for a fuel cell according to any one of claims 1 to 8.

10. The outer groove flow path, which is the groove flow path located outermost in the arrangement direction, has a portion located at the same position as the outer edge of the contact surface or outside the outer edge in the arrangement direction. The separator for a fuel cell according to any one of claims 2 to 9.

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