Single cell of fuel cell

Abstract

A single cell of a fuel cell is provided with a power generation unit and a pair of separators that sandwich the power generation unit. Each of the separators has an opposing surface that opposes the power generation unit. The facing surface is provided with a gas flow path and a plurality of ribs. The gas flow path has: a mesh section; an inflow part configured so as to cause the reaction gas to flow into the mesh part; and an outflow part configured so as to cause the reaction gas to flow out from the mesh part. The plurality of ribs constituting the mesh of the mesh portion include a plurality of ribs arranged in one direction. The length in the one direction of the plurality of ribs arranged in the one direction increases or decreases in stages at least for each rib from the inflow portion side toward the outflow portion side.

Description

Technical Field

[0001] The present disclosure relates to a single cell of a fuel cell. Background Art

[0002] Currently, a single fuel cell is known, for example, as described in Japanese Patent Application Laid-Open No. 2022-182065. This single cell has a structure in which a power generation unit, supported by a frame member, is sandwiched between a pair of separators. Each separator has a grooved flow path for supplying reactant gases to the power generation unit. The grooved flow path in each separator extends in a wavy pattern and has multiple branched flow paths and a confluence where the multiple branched flow paths merge from the upstream side to the downstream side. Summary of the Invention

[0003] Problems to be solved by the invention

[0004] However, in the above-described single cell, the groove flow paths of each separator have the above-described structure, but there is still room for improvement in terms of efficiently supplying the reaction gas to the power generation section.

[0005] Furthermore, in the above-described fuel cell unit, the groove flow paths of each separator have the above-described structure, but there is still room for improvement in terms of uniformly supplying the reactant gas to the entire power generation section.

[0006] Solutions to Problems

[0007] A fuel cell according to a first aspect of the present disclosure includes a power generation section including a membrane electrode assembly and a pair of separators sandwiching the power generation section. Each separator has an opposing surface opposing the power generation section, and a gas flow path configured to flow a reactant gas and a plurality of ribs adjacent to the gas flow path are provided on the opposing surface. The gas flow path includes a mesh portion formed in a mesh-like manner in a region of the opposing surface corresponding to the power generation section; an inlet portion connected to one end of the mesh portion in one direction and configured to allow the reactant gas to flow into the mesh portion; and an outlet portion connected to the other end of the mesh portion in the one direction, located opposite the one end, and configured to allow the reactant gas to flow out of the mesh portion. The mesh of the mesh portion is formed by the plurality of ribs, and the plurality of ribs constituting the mesh include a plurality of ribs arranged along the one direction. The length of the plurality of ribs arranged along the one direction gradually increases or decreases at least for each rib as it moves from the inlet portion toward the outlet portion.

[0008] A fuel cell according to a second aspect of the present disclosure includes a power generation section including a membrane electrode assembly and a pair of separators sandwiching the power generation section, each separator having an opposing surface opposing the power generation section, a gas flow path configured to allow a reactant gas to flow provided on the opposing surface, the gas flow path comprising: a mesh portion formed in a mesh-like manner in a region of the opposing surface corresponding to the power generation section; an inlet portion provided at a first end portion of the mesh portion in one direction, configured to allow the reactant gas to flow into the mesh portion; an outlet portion provided at a second end portion of the mesh portion in the one direction opposite to the first end portion, configured to allow the reactant gas to flow out of the mesh portion; and a suppression flow path constituting a portion of the mesh portion and configured to increase pressure loss during the flow of the reactant gas compared to other portions of the mesh portion, the suppression flow path being arranged in the mesh portion so as to connect the inlet portion and the outlet portion by the shortest distance.

[0009] A fuel cell cell according to a third embodiment of the present disclosure comprises a power generation section including a membrane electrode assembly and a pair of separators sandwiching the power generation section, each separator having an opposing surface opposing the power generation section, a gas flow path configured to allow a reaction gas to flow provided on the opposing surface, the gas flow path comprising: a mesh portion formed in a mesh-like manner in a region corresponding to the power generation section on the opposing surface; an inflow portion provided at a first end portion in one direction of the mesh portion and configured to allow the reaction gas to flow into the mesh portion; an outflow portion provided at a second end portion in the one direction of the mesh portion located on the opposite side of the first end portion and configured to allow the reaction gas to flow out of the mesh portion; and a suppression flow path constituting a portion of the mesh portion and configured to increase a pressure loss when the reaction gas flows compared to other portions of the mesh portion, the suppression flow path being arranged in the mesh portion so as to separate the inflow portion from the outflow portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view showing a fuel cell stack including single cells of the fuel cell according to the first embodiment.

[0011] Figure 2 Yes Figure 1 Exploded perspective view of a single battery.

[0012] Figure 3 Yes Figure 1 Top view of the gas flow path of the separator.

[0013] Figure 4 Yes Figure 1 A plan view showing the positional relationship between the gas flow paths of a pair of separators in a single cell.

[0014] Figure 5 It is a plan view showing a gas flow path of a separator according to a modified example.

[0015] Figure 6 It is a plan view showing a gas flow path of a separator according to a modified example.

[0016] Figure 7 It is a plan view showing a gas flow path of a separator according to a modified example.

[0017] Figure 8 It is a plan view showing a gas flow path of a separator according to a modified example.

[0018] Figure 9 It is a plan view showing a gas flow path of a separator according to a modified example.

[0019] Figure 10 It is a cross-sectional view showing a fuel cell stack including single cells of the fuel cell according to the second embodiment.

[0020] Figure 11 Yes Figure 10 Exploded perspective view of a single battery.

[0021] Figure 12 Yes Figure 10 Top view of the gas flow path of the separator.

[0022] Figure 13 Yes Figure 10 An angled top view of the ribs of the separator.

[0023] Figure 14 Yes Figure 10 A plan view showing the positional relationship between the gas flow paths of a pair of separators in a single cell.

[0024] Figure 15 It is a plan view showing a gas flow path of a separator according to a modified example.

[0025] Figure 16 It is a plan view showing a gas flow path of a separator according to another modified example.

[0026] Figure 17 It is a plan view showing a gas flow path of a separator according to still another modified example. DETAILED DESCRIPTION

[0027] First embodiment

[0028] Below, according to Figures 1 to 4 The fuel cell unit cell 12 of the first embodiment will be described.

[0029] Fuel Cell Stack 11

[0030] like Figure 1 As shown, the fuel cell stack 11 is constructed by stacking a plurality of plate-shaped cells 12 .

[0031] <Single cell 12>

[0032] like Figure 2 As shown, the cell 12 is formed in a rectangular plate shape, for example. Specifically, the cell 12 has a pair of long sides 13 extending parallel to each other and a pair of short sides 14 extending parallel to each other and perpendicular to the long sides 13 .

[0033] Hereinafter, the stacking direction Z, which coincides with the thickness direction of the cell 12, will be referred to simply as the stacking direction Z. Furthermore, the direction in which the long side 13 extends will be referred to as the X-axis direction, and the direction in which the short side 14 extends will be referred to as the Y-axis direction. The stacking direction Z, the X-axis direction, and the Y-axis direction are orthogonal to each other.

[0034] The cell 12 includes a fuel gas supply manifold M1 for supplying fuel gas into the cell 12 and a fuel gas exhaust manifold M2 for exhausting the fuel gas to the outside of the cell 12. The cell 12 also includes an oxidant gas supply manifold M3 for supplying oxidant gas into the cell 12 and an oxidant gas exhaust manifold M4 for exhausting the oxidant gas to the outside of the cell 12.

[0035] like Figure 1 and Figure 2 As shown, the cell 12 includes a coolant supply manifold M5 for supplying a coolant to the interior of the fuel cell stack 11 and a coolant discharge manifold M6 for discharging the coolant to the exterior of the fuel cell stack 11. The manifolds M1 to M6 are formed in, for example, a rectangular shape.

[0036] like Figure 2 As shown, the fuel gas supply manifold M1, the refrigerant supply manifold M5, and the oxidant gas exhaust manifold M4 are located at one end of the cell 12 in the X-axis direction. The fuel gas supply manifold M1, the refrigerant supply manifold M5, and the oxidant gas exhaust manifold M4 are arranged sequentially from one side to the other in the Y-axis direction. The fuel gas exhaust manifold M2, the refrigerant exhaust manifold M6, and the oxidant gas supply manifold M3 are located at the other end of the cell 12, opposite to the one end in the X-axis direction. The fuel gas exhaust manifold M2, the refrigerant exhaust manifold M6, and the oxidant gas supply manifold M3 are arranged sequentially from the other side to the one in the Y-axis direction. For example, the fuel gas is hydrogen. For example, the oxidant gas is air. For example, the cooling medium is water.

[0037] The cell 12 includes a power generation unit 15, a frame 16, and a pair of separators 17. The power generation unit 15 is formed in a sheet shape. The frame 16 surrounds the outer periphery of the power generation unit 15. The pair of separators 17 sandwich the power generation unit 15 and the frame 16 from both sides in the stacking direction Z. The power generation unit 15 and the separators 17 are formed in a rectangular shape, for example, when viewed from above. The frame 16 is formed in a rectangular frame shape, for example, when viewed from above.

[0038] <Power Generation Unit 15>

[0039] like Figure 1 As shown, the power generation section 15 includes a membrane electrode assembly 18, an anode-side gas diffusion layer 19, and a cathode-side gas diffusion layer 20 sandwiching the membrane electrode assembly 18. The membrane electrode assembly 18 includes an electrolyte membrane and anode and cathode electrode catalyst layers sandwiching the electrolyte membrane, though these are not shown. The anode-side gas diffusion layer 19 is laminated on the anode electrode catalyst layer. The cathode-side gas diffusion layer 20 is laminated on the cathode electrode catalyst layer.

[0040] like Figure 1 and Figure 2 As shown, fuel gas is supplied to the anode side of the power generation section 15 through the fuel gas supply manifold M1. Oxidant gas is supplied to the cathode side of the power generation section 15 through the oxidant gas supply manifold M3. Thus, in the power generation section 15, power generation is generated by the electrochemical reaction between the fuel gas and the oxidant gas.

[0041] In the fuel cell stack 11, each cell 12 generates heat as the power generation section 15 generates electricity. Therefore, a cooling flow path 21, described below, is formed inside the fuel cell stack 11. A cooling medium is supplied to the cooling flow path 21 through a coolant supply manifold M5.

[0042] <Frame 16>

[0043] like Figure 2 As shown, the frame 16 is formed of an insulating resin material. The frame 16 has a housing hole 22 in the center portion for housing the power generation unit 15. The frame 16 has through holes hf1 to hf6 on the outer periphery of the housing hole 22, which constitute the manifolds M1 to M6.

[0044] <Separator 17>

[0045] like Figure 1 and Figure 2 As shown, separator 17 is formed by press-forming a metal plate such as stainless steel or titanium alloy. One of the pair of separators 17 is disposed on the anode side of power generation section 15, and the other is disposed on the cathode side of power generation section 15.

[0046] In the following description, the separator 17 disposed on the anode side of the power generation section 15 is sometimes referred to as the anode separator 24 , and the separator 17 disposed on the cathode side of the power generation section 15 is sometimes referred to as the cathode separator 25 .

[0047] The anode separator 24 and the cathode separator 25 have the same structure. The anode separator 24 and the cathode separator 25 are arranged in a reversed position relative to the power generation section 15, with the imaginary axis V serving as the reverse axis. The imaginary axis V is an axis that passes through the center of the separator 17 in the X-axis direction and extends along the Y-axis direction.

[0048] The separator 17 has through-holes hs1 to hs6 that constitute the manifolds M1 to M6. As described above, the anode separator 24 and cathode separator 25 are arranged in an inverted position relative to the power generation section 15. Therefore, the through-hole hs1 of the anode separator 24 and the through-hole hs3 of the cathode separator 25 communicate with each other, and the through-hole hs2 of the anode separator 24 and the through-hole hs4 of the cathode separator 25 communicate with each other.

[0049] The through-hole hs3 of the anode separator 24 communicates with the through-hole hs1 of the cathode separator 25, and the through-hole hs4 of the anode separator 24 communicates with the through-hole hs2 of the cathode separator 25. The through-hole hs5 of the anode separator 24 communicates with the through-hole hs6 of the cathode separator 25, and the through-hole hs6 of the anode separator 24 communicates with the through-hole hs5 of the cathode separator 25.

[0050] like Figure 2 and Figure 3 As shown, separator 17 has an opposing surface 26 that faces power generation section 15. Opposing surface 26 is provided with groove-shaped gas flow paths 27 for the flow of reactant gas, and a plurality of ribs 28 adjacent to gas flow paths 27. Gas flow paths 27 include a mesh-like mesh portion 29, an inflow portion 30 for allowing reactant gas to flow into mesh portion 29, and an outflow portion 31 for allowing reactant gas to flow out of mesh portion 29.

[0051] The mesh portion 29 of the gas flow path 27 is formed in a region of the opposing surface 26 corresponding to the power generation section 15 and having a generally rectangular shape when viewed from above. The mesh of the mesh portion 29 is composed of a plurality of ribs 28. Therefore, in the mesh portion 29, the gas flow path 27 extends in a manner surrounding the plurality of ribs 28. That is, in the mesh portion 29, the gas flow path 27 extends along the contours of the plurality of ribs 28. In this embodiment, the ribs 28 have a hexagonal shape when viewed from above. The mesh portion 29 of the gas flow path 27 has a plurality of branch portions 32 that branch from one flow path into two flow paths, and a plurality of confluence portions 33 that merge two flow paths into one flow path.

[0052] The plurality of ribs 28 constituting the mesh of the mesh portion 29 are arranged in the X-axis and Y-axis directions. The X-axis direction is an example of "one direction." The Y-axis direction is an example of "a direction perpendicular to one direction." The length L in the X-axis direction of the plurality of ribs 28 constituting the mesh of the mesh portion 29, arranged along the X-axis direction, gradually decreases for each rib 28 as it moves from the inflow portion 30 side toward the outflow portion 31 side.

[0053] That is, Figure 3 As shown, when the plurality of ribs 28 arranged along the X-axis direction are arranged in the order of rib 28A, rib 28B, rib 28C, rib 28D, and rib 28E from the inflow portion 30 side toward the outflow portion 31 side, the relationship between the values of their length L in the X-axis direction is rib 28A > rib 28B > rib 28C > rib 28D > rib 28E. The width H of the ribs 28 in the Y-axis direction is preferably 2 mm or less, and more preferably 1.5 mm or less.

[0054] The inflow portion 30 is connected to one end of the mesh portion 29 in the X-axis direction, and the outflow portion 31 is connected to the other end of the mesh portion 29 in the X-axis direction, located opposite to the one end. Both the inflow portion 30 and the outflow portion 31 are composed of a plurality (six in this embodiment) of flow paths extending linearly along the X-axis direction and arranged parallel to each other and at equal intervals in the Y-axis direction. The multiple flow paths comprising the inflow portion 30 are longer in the X-axis direction than the multiple flow paths comprising the outflow portion 31.

[0055] like Figure 2 and Figure 4 As shown, when the cell 12 is viewed from the stacking direction Z, the mesh portion 29 and ribs 28 of the gas flow path 27 of the anode separator 24 and the mesh portion 29 and ribs 28 of the gas flow path 27 of the cathode separator 25 are offset in the X-axis direction. Figure 4 In FIG. 1 , the gas flow path 27 of the anode separator 24 is indicated by a solid line, and the gas flow path 27 of the cathode separator 25 is indicated by a two-dot chain line.

[0056] like Figure 2 and Figure 3 As shown, the ends of the plurality of flow paths constituting the inflow portion 30, which are located on the side opposite to the mesh portion 29, are connected to the through-hole hs1 via a plurality of upstream connecting flow paths 34. The ends of the plurality of flow paths constituting the outflow portion 31, which are located on the side opposite to the mesh portion 29, are connected to the through-hole hs2 via a plurality of downstream connecting flow paths 35.

[0057] Fuel gas, which is a reactant gas, flows through the gas flow path 27 of the anode separator 24 . Oxidant gas, which is a reactant gas, flows through the gas flow path 27 of the cathode separator 25 . The reactant gas flows through the gas flow path 27 and is supplied to the power generation unit 15 .

[0058] <Cooling flow path 21>

[0059] like Figure 1 As shown, in the fuel cell stack 11 , the anode separator 24 constituting one of two adjacent cells 12 in the stacking direction Z and the cathode separator 25 constituting the other cell 12 are in contact with each other.

[0060] A cooling channel 21 for the flow of a cooling medium is formed between the anode separator 24 and cathode separator 25 that contact each other in two adjacent cells 12 in the stacking direction Z. A gasket is provided between the anode separator 24 and cathode separator 25 that contact each other to seal the two cells 12, although this gasket is not shown.

[0061] like Figure 1 and Figure 2 As shown, the separator 17 has a plurality of cooling grooves 36 that constitute the cooling flow path 21. The cooling grooves 36 are formed on the surface of the separator 17 opposite the surface where the gas flow path 27 is formed. The cooling grooves 36 are formed by the back surface shape of the ribs 28. The cooling flow path 21 is formed by the gap between the cooling grooves 36 of the anode separator 24 and the cooling grooves 36 of the cathode separator 25. The cooling medium supplied from the refrigerant supply manifold M5 flows through the cooling flow path 21 and is discharged from the refrigerant discharge manifold M6.

[0062] <Function of the First Embodiment>

[0063] When power generation is generated by the single cell 12, the reactant gas is supplied from the through-hole hs1 of the separator 17 to the gas flow path 27 and then discharged from the through-hole hs2. Specifically, in the gas flow path 27, the reactant gas flows in the order of the inlet 30, the mesh portion 29, and the outlet 31. The reactant gas flows through the mesh portion 29 of the gas flow path 27 and is supplied to the power generation section 15. In the power generation section 15, power generation is generated by the electrochemical reaction generated by the reactant gas.

[0064] Here, the mesh portion 29 corresponding to the power generation section 15 has a plurality of confluences 33 where the reactant gases merge. In the gas flow path 27, the pressure loss of the reactant gases downstream of the confluences 33 is greater than the pressure loss of the reactant gases upstream of the confluences 33. Therefore, the amount of reactant gas flowing into the power generation section 15 increases in the portion of the gas flow path 27 downstream of the plurality of confluences 33 compared to the portion upstream of the confluences 33.

[0065] Furthermore, the length L in the X-axis direction of the plurality of ribs 28 arranged along the X-axis direction gradually decreases for each rib 28 as it moves from the inflow portion 30 side toward the outflow portion 31 side. Therefore, when stacking a plurality of cells 12 having a structure in which a pair of separators 17 are reversed about an imaginary axis V with one end portion in the X-axis direction swapped with the other end portion, the positions of the gas flow paths 27 and ribs 28 of the mutually contacting separators 17 in two adjacent cells 12 in the stacking direction Z are offset from each other in the X-axis direction.

[0066] This prevents the concave and convex portions of the separator 17 forming the gas flow paths 27 and ribs 28 in contacting each other in two adjacent cells 12 in the stacking direction Z from interlocking with each other. Consequently, the surface pressure of the facing surface 26 of the separator 17 against the power generation section 15 can be maintained uniformly and stably, thereby improving the close contact between the facing surface 26 of the separator 17 and the power generation section 15. Consequently, the reactant gas is efficiently supplied from the gas flow paths 27 to the power generation section 15.

[0067] <Effects of the First Embodiment>

[0068] According to the first embodiment described in detail above, the following effects can be achieved.

[0069] (1-1) In the cell 12 , the length L in the X-axis direction of the plurality of ribs 28 arranged along the X-axis direction of the mesh of the mesh portion 29 constituting the gas flow path 27 gradually decreases for each rib 28 as it moves from the inlet 30 side toward the outlet 31 side.

[0070] According to the above configuration, as described above in terms of the effects of the first embodiment, the reaction gas can be efficiently supplied from the gas flow path 27 to the power generation section 15 .

[0071] (1-2) In the single cell 12 , the pair of separators 17 have the same structure as each other.

[0072] According to the above configuration, the pair of separators 17 can be made into a common component, and thus the number of components can be reduced compared to a case where the pair of separators 17 are made into different structures.

[0073] (1-3) In the single cell 12 , the width H of the rib 28 in the Y-axis direction is 2 mm or less.

[0074] According to the above configuration, it is possible to suppress the shortage of the reaction gas supplied to the portion of the power generation section 15 that is in contact with the ribs 28 .

[0075] <Change Example>

[0076] The first embodiment can be implemented by modifications as follows: The first embodiment and the following modifications can be implemented in combination with each other within a range where there is no technical contradiction.

[0077] ·like Figure 5 As shown, a configuration may also be employed in which the ribs 28 are diamond-shaped, and the mesh portion 29 of the gas flow path 27 is configured such that a single diamond-shaped annular flow path 40 surrounding the rib 28 and a linear flow path 41 extending along the X-axis are alternately arranged in the X-axis direction. In this case, the length L of the plurality of ribs 28 arranged along the X-axis direction may gradually increase or decrease from one side of the X-axis direction toward the other.

[0078] ·like Figure 6 As shown, the ribs 28 may be triangular in shape, and the mesh portion 29 of the gas flow path 27 may be configured such that a triangular annular flow path 42 surrounding the rib 28 and a linear flow path 41 extending along the X-axis are alternately arranged in the X-axis direction. In this case, the length L of the plurality of ribs 28 arranged along the X-axis direction may gradually increase or decrease from one side of the X-axis direction to the other.

[0079] ·like Figure 7 As shown, the ribs 28 may be formed into a hexagonal shape rotated 90 degrees, and the mesh portion 29 of the gas flow path 27 may be configured such that a single hexagonal flow path 43 surrounding the rib 28 and a pair of linear flow paths 44 arranged along the Y-axis and extending along the X-axis are alternately arranged in the X-axis direction. In this case, the length L of the plurality of ribs 28 arranged along the X-axis direction may gradually increase or decrease from one side of the X-axis direction to the other.

[0080] ·like Figure 8 As shown, the ribs 28 may be formed into a hexagonal shape rotated 90°, and the mesh portion 29 of the gas flow path 27 may be formed into a structure in which three series of hexagonal ring-shaped flow paths 43 connected in the X-axis direction and surrounding the ribs 28 are alternately arranged in the X-axis direction with a pair of linear flow paths 44 arranged in the Y-axis direction and extending in the X-axis direction. In this case, the length L in the X-axis direction of the three series of ribs 28 arranged in the X-axis direction may gradually increase or decrease from one side of the X-axis direction to the other.

[0081] ·like Figure 9 As shown, the mesh portion 29 of the gas flow path 27 may be configured such that the branching portion 32 branches one flow path into three flow paths and the merging portion 33 merges the three flow paths into one flow path.

[0082] The mesh portion 29 of the gas flow path 27 may be configured such that the branching portion 32 branches one flow path into four or more flow paths, and the merging portion 33 merges the four or more flow paths into one flow path.

[0083] The width H of the rib 28 in the Y-axis direction does not necessarily need to be 2 mm or less.

[0084] The pair of separators 17 may have different structures from each other.

[0085] The gas flow path 27 may be configured so that the width of the portion downstream of the branching portion 32, where the reactant gas branches, is narrower than the width of the portion upstream of the branching portion 32. Typically, in the gas flow path 27, the pressure loss of the reactant gas downstream of the branching portion 32 is smaller than the pressure loss of the reactant gas upstream of the branching portion 32. In this regard, this configuration increases the pressure loss of the reactant gas downstream of the branching portion 32 in the gas flow path 27, thereby increasing the amount of reactant gas flowing from the gas flow path 27 into the power generation section 15.

[0086] The gas flow path 27 may be configured such that the width of a portion downstream of the branch portion 32 that branches the reaction gas is wider than the width of a portion upstream of the branch portion 32 .

[0087] In the cell 12 , the length L in the X-axis direction of the plurality of ribs 28 arranged along the X-axis direction of the mesh of the mesh portion 29 constituting the gas flow path 27 may be gradually increased for each rib 28 as it moves from the inlet 30 side toward the outlet 31 side.

[0088] In the single cell 12 , the length L in the X-axis direction of the plurality of ribs 28 arranged along the X-axis direction of the mesh of the mesh portion 29 constituting the gas flow path 27 may be gradually lengthened or shortened for each two or more ribs 28 as it moves from the inlet portion 30 side toward the outlet portion 31 side.

[0089] The length L of the rib 28A and the length L of the rib 28B may be the same.

[0090] The length L of the rib 28B and the length L of the rib 28C may be made the same.

[0091] The length L of the rib 28C and the length L of the rib 28D may be made the same.

[0092] The length L of the rib 28D and the length L of the rib 28E may be made the same.

[0093] The shape of the separator 17 is not limited to a rectangular shape, and may be a polygonal shape (for example, a hexagonal shape or an octagonal shape), a circular shape, or an elliptical shape other than a rectangular shape.

[0094] The shape of the rib 28 is not limited to a hexagonal shape, and may be a polygonal shape other than a hexagonal shape (for example, a quadrangular shape or an octagonal shape).

[0095] Second embodiment

[0096] Below, according to Figures 10 to 14 The single cell 112 of the fuel cell according to the second embodiment will be described focusing on the differences from the first embodiment.

[0097] Fuel Cell Stack 111

[0098] like Figure 10 As shown, the fuel cell stack 111 is constructed by stacking a plurality of plate-shaped cells 112. In the following description, components identical or corresponding to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and redundant description is omitted.

[0099] <Single cell 112>

[0100] like Figure 11 As shown, the cell 112 is formed in, for example, a rectangular plate shape and includes a power generation unit 15 , a frame 16 , and a pair of separators 117 .

[0101] <Separator 117>

[0102] like Figure 10 and Figure 11 As shown, separator 117 is formed by press-forming a metal plate such as stainless steel or titanium alloy. One of the pair of separators 117 is disposed on the anode side of power generation section 15, and the other is disposed on the cathode side of power generation section 15.

[0103] In the following description, the separator 117 disposed on the anode side of the power generation section 15 is sometimes referred to as the anode separator 124 , and the separator 117 disposed on the cathode side of the power generation section 15 is sometimes referred to as the cathode separator 125 .

[0104] The anode separator 124 and the cathode separator 125 have the same structure. The anode separator 124 and the cathode separator 125 are arranged in a reversed position relative to the power generation section 15, with the imaginary axis V as the reverse axis. The imaginary axis V is an axis that passes through the center of the separator 117 in the X-axis direction and extends along the Y-axis direction.

[0105] Similar to the first embodiment, the separator 117 has through holes hs1 to hs6 constituting the manifolds M1 to M6 .

[0106] like Figure 11 and Figure 12As shown, separator 117 has an opposing surface 126 that faces power generation section 15. Opposing surface 126 is provided with groove-shaped gas flow paths 127 through which the reactant gas flows, and ribs 128 adjacent to gas flow paths 127. Gas flow paths 127 include a mesh-like mesh portion 129, an inflow portion 130 for allowing the reactant gas to flow into mesh portion 129, and an outflow portion 131 for allowing the reactant gas to flow out of mesh portion 129.

[0107] The mesh portion 129 of the gas flow path 127 is formed over the entire rectangular region of the facing surface 126 corresponding to the power generation section 15 when viewed from above. That is, the mesh portion 129 is formed as a whole into a rectangular shape corresponding to the power generation section 15. The meshes of the mesh portion 129 are formed by ribs 128. Thus, the gas flow path 127 extends through the mesh portion 129 so as to surround the ribs 128. The ribs 128 are formed into a hexagonal shape as an example of a polygon.

[0108] like Figure 11 、 Figure 13 ,and Figure 14 As shown, the ribs 128 extend obliquely with respect to the long side 13 of the separator 117. The angle A formed by the direction in which the ribs 128 extend and the direction in which the long side 13 extends is set to 45 degrees, for example. Therefore, when the single cell 112 is viewed from the stacking direction Z, the mesh portion 129 and the ribs 128 of the gas flow path 127 of the anode separator 124 intersect with the mesh portion 129 and the ribs 128 of the gas flow path 127 of the cathode separator 125. Figure 14 In FIG. 1 , the gas flow path 127 of the anode separator 124 is indicated by a solid line, and the gas flow path 127 of the cathode separator 125 is indicated by a two-dot chain line.

[0109] like Figure 11 and Figure 12 As shown, an inlet portion 130 for allowing the reactant gas to flow into the mesh portion 129 is provided at a first end portion 132 in the X-axis direction of the mesh portion 129. An outflow portion 131 for allowing the reactant gas to flow out of the mesh portion 129 is provided at a second end portion 133 in the X-axis direction, located opposite to the first end portion 132. The inlet portion 130 and the outflow portion 131 are formed, for example, from a plurality of grooves (three in this embodiment) extending linearly along the X-axis direction and arranged at equal intervals in the Y-axis direction.

[0110] The inflow portion 130 is provided at one end of the mesh portion 129 in the X-axis direction, and the outflow portion 131 is provided at the other end of the mesh portion 129 in the X-axis direction. Specifically, the inflow portion 130 and the outflow portion 131 provided in the mesh portion 129 are located at opposite ends in the Y-axis direction. The X-axis direction is an example of "one direction." The inflow portion 130 connects the through-hole hs1 and the mesh portion 129. The outflow portion 131 connects the through-hole hs2 and the mesh portion 129.

[0111] A portion of the mesh portion 129 is formed of a suppression flow path 134. The suppression flow path 134 is configured to cause a greater pressure loss during the flow of reactant gas than other portions of the mesh portion 129. The mesh portion 129 includes the suppression flow path 134 and a general flow path 135 within the mesh portion 129, which is not part of the suppression flow path 134. The suppression flow path 134 has a narrower flow path width than the general flow path 135. Therefore, the pressure loss during the flow of reactant gas in the suppression flow path 134 is greater than that in the general flow path 135.

[0112] The flow path width of the suppression flow path 134 is set to, for example, about half the flow path width of the general flow path 135. The suppression flow path 134 is arranged in the mesh portion 129 so as to connect the inflow portion 130 and the outflow portion 131 with the shortest distance. That is, the suppression flow path 134 is arranged in an area along the straight line connecting the inflow portion 130 and the outflow portion 131 (in the region of the mesh portion 129). Figure 12 area enclosed by dotted lines).

[0113] like Figure 11 and Figure 12 As shown, fuel gas as a reactant gas flows through the gas flow path 127 of the anode separator 124 . Oxidant gas as a reactant gas flows through the gas flow path 127 of the cathode separator 125 . The reactant gas flows through the gas flow path 127 and is supplied to the power generation unit 15 .

[0114] like Figure 10 and Figure 11 As shown, the separator 117 has a plurality of cooling grooves 136 constituting the cooling flow path 21 , similarly to the first embodiment.

[0115] <Function of the Second Embodiment>

[0116] When power generation is generated by the single cell 112, the reactant gas is supplied from the through-hole hs1 of the separator 117 to the gas flow path 127 and then discharged from the through-hole hs2. Specifically, in the gas flow path 127, the reactant gas flows in the order of the inlet 130, the mesh portion 129, and the outlet 131. The reactant gas flows through the mesh portion 129 of the gas flow path 127 and is supplied to the power generation section 15. In the power generation section 15, power generation is generated by the electrochemical reaction generated by the reactant gas.

[0117] In the absence of the suppression flow path 134 in the mesh portion 129 corresponding to the power generation section 15 , the reactant gas typically flows primarily along the shortest path from the inlet 130 to the outlet 131 , resulting in a biased flow of the reactant gas. Consequently, the reactant gas has difficulty flowing to every corner of the mesh portion 129 , making it difficult to achieve a uniform flow of the reactant gas throughout the mesh portion 129 .

[0118] To address this issue, according to the second embodiment, the suppression flow paths 134, which experience a greater pressure loss when reactant gas flows than the normal flow paths 135, are arranged in the mesh portion 129 so as to connect the inlet 130 and the outlet 131 at the shortest distance. Consequently, the difference in the amount of reactant gas flowing between the normal flow paths 135 and the suppression flow paths 134 in the mesh portion 129 is minimized.

[0119] Therefore, the reactant gas can flow to every corner of the mesh portion 129, eliminating any uneven flow of the reactant gas within the mesh portion 129. Consequently, the reactant gas can flow evenly throughout the mesh portion 129, allowing the reactant gas to be evenly supplied throughout the power generation section 15. This improves the power generation efficiency of the power generation section 15.

[0120] <Effects of the Second Embodiment>

[0121] According to the second embodiment described in detail above, the following effects can be achieved.

[0122] (2-1) In the cell 112 , the suppression flow path 134 is arranged in the mesh portion 129 so as to connect the inflow portion 130 and the outflow portion 131 with the shortest distance.

[0123] According to the above configuration, as described above in connection with the operation of the second embodiment, the flow of the reactant gas in the mesh portion 129 of the gas flow path 127 is eliminated, thereby allowing the reactant gas to flow uniformly throughout the mesh portion 129. Consequently, the reactant gas can be uniformly supplied to the entire power generation section 15.

[0124] (2-2) In the single cell 112 , the pair of separators 117 have the same structure.

[0125] According to the above configuration, the pair of separators 117 can be made into a common component, and thus the number of components can be reduced compared to a case where the pair of separators 117 are made into different structures.

[0126] (2-3) In the cell 112 , the separator 117 is formed in a rectangular shape. The meshes of the mesh portion 129 are formed of hexagonal ribs 128 . The ribs 128 extend obliquely with respect to the long sides 13 of the separator 117 .

[0127] With this structure, when viewed from the stacking direction Z in which the pair of separators 117 sandwich the power generation unit 15, the mesh portions 129 of the gas flow paths 127 of the pair of separators 117 intersect with each other. Therefore, when multiple cells 112 are stacked, the concave and convex portions of the separators 117 forming the gas flow paths 127 and ribs 128 in two adjacent cells 112 in the stacking direction Z are prevented from interlocking. Consequently, close contact between the facing surfaces 126 of the separators 117 and the power generation unit 15 is maintained.

[0128] <Change Example>

[0129] The second embodiment described above can be implemented by modifications as follows: The second embodiment and the following modifications can be implemented in combination with each other within a range where there is no technical contradiction.

[0130] ·like Figure 15 As shown, the suppression flow path 134 may be arranged in the mesh portion 129 so as to separate the inflow portion 130 and the outflow portion 131. In this case, the suppression flow path 134 extends over the entire mesh portion 129 in the Y-axis direction. That is, the suppression flow path 134 is arranged in a region along a straight line extending in the Y-axis direction (in the region of the mesh portion 129) so as to separate the inflow portion 130 and the outflow portion 131. Figure 15 area enclosed by dotted lines).

[0131] In the absence of the suppression flow path 134 in the mesh portion 129, the reactant gas typically flows primarily along the shortest path from the inlet 130 to the outlet 131, resulting in a biased flow of the reactant gas. Consequently, the reactant gas has difficulty flowing to every corner of the mesh portion 129, making it difficult to achieve a uniform flow of the reactant gas throughout the mesh portion 129.

[0132] To address this issue, according to this structure, the suppression flow path 134, which experiences a greater pressure loss when reactant gas flows than the general flow path 135 in the mesh portion 129, is arranged in the mesh portion 129 to separate the inlet portion 130 from the outlet portion 131. Therefore, reactant gas flowing from the inlet portion 130 into the mesh portion 129 flows through the entire portion of the mesh portion 129 closer to the inlet portion 130 than the suppression flow path 134, then flows through the suppression flow path 134 and the entire portion of the mesh portion 129 closer to the outlet portion 131 than the suppression flow path 134, before exiting the mesh portion 129 toward the outlet portion 131. Consequently, any flow bias in the reactant gas within the mesh portion 129 of the gas flow path 127 is eliminated, allowing the reactant gas to flow evenly throughout the mesh portion 129. This allows the reactant gas to be uniformly supplied to the entire power generation section 15.

[0133] ·like Figure 16 As shown, the suppression flow path 134 may be arranged in the mesh portion 129 so as to separate the inflow portion 130 and the outflow portion 131. In this case, the suppression flow path 134 extends over the entire mesh portion 129 in the X-axis direction. That is, the suppression flow path 134 is arranged in a region along a straight line extending in the X-axis direction (in the region of the mesh portion 129) so as to separate the inflow portion 130 and the outflow portion 131. Figure 16 Even with this configuration, the same as above can be obtained. Figure 15 The same effect occurs in the same situation.

[0134] ·like Figure 17 As shown, the suppression flow path 140 may be arranged in the mesh portion 129 in a manner that separates the inflow portion 130 from the outflow portion 131. In this case, the suppression flow path 140 is arranged in a linear region extending along a diagonal line on one side of the mesh portion 129 (in Figure 17 (The area surrounded by dotted lines in FIG. 1 ). In this case, the suppression flow path 140 is configured such that, although the flow path width is the same as that of the general flow path 135, it forms a shorter hexagon and a longer hexagon than the hexagon formed by the general flow path 135. Since the short hexagonal flow path constituting the suppression flow path 140 is significantly bent compared to the hexagonal flow path constituting the general flow path 135, the pressure loss during the flow of the reaction gas is greater than that of the general flow path 135. Since the long hexagonal flow path constituting the suppression flow path 140 is longer than the hexagonal flow path constituting the general flow path 135, the pressure loss during the flow of the reaction gas is greater than that of the general flow path 135. The suppression flow path 140 arranged in the area extending in a straight line is configured such that, for example, the hexagon in the center is the shortest and the length of the hexagon increases toward the two ends. In this case, the pressure loss during the flow of the reaction gas in the suppression flow path 140 arranged in the straight line is the highest in the center and decreases toward the two ends. Even with this configuration, the above Figure 15The same effect occurs in the same situation.

[0135] The shape of the separator 117 is not limited to a rectangular shape, and may be a polygonal shape (for example, a hexagonal shape or an octagonal shape), a circular shape, or an elliptical shape other than a rectangular shape.

[0136] The shape of the rib 128 is not limited to a hexagonal shape, and may be a polygon other than a hexagonal shape (for example, a quadrilateral or an octagonal shape), a circular shape, or an elliptical shape.

[0137] The pair of separators 117 in the single cell 112 may have different structures from each other.

Claims

1. A fuel cell comprising a power generation unit including a membrane electrode assembly and a pair of separators sandwiching the power generation unit. Each separator has an opposing surface facing the power generation portion, and a gas flow path configured to allow a reaction gas to flow and a plurality of ribs adjacent to the gas flow path are provided on the opposing surface. The gas flow path has: a mesh portion formed in a mesh shape in a region of the opposing surface corresponding to the power generation portion; an inflow portion connected to one end portion in one direction of the mesh portion and configured to allow the reaction gas to flow into the mesh portion; as well as an outflow portion connected to the other end portion of the mesh portion located on the opposite side of the one end portion in the one direction, and configured to allow the reaction gas to flow out of the mesh portion, The mesh of the net-like portion is formed by the plurality of ribs. The plurality of ribs constituting the mesh include a plurality of ribs arranged along the one direction, The length of the plurality of ribs arranged along the one direction in the one direction becomes longer or shorter in stages at least for each rib as it moves from the inflow portion side toward the outflow portion side.

2. The fuel cell according to claim 1, wherein: The pair of separators have the same structure as each other.

3. The fuel cell according to claim 1 or 2, wherein: The width of the rib in a direction perpendicular to the one direction is 2 mm or less.

4. A fuel cell comprising a power generation unit including a membrane electrode assembly and a pair of separators sandwiching the power generation unit. Each separator has an opposing surface facing the power generation portion, and a gas flow path configured to allow the reaction gas to flow is provided on the opposing surface. The gas flow path has: a mesh portion formed in a mesh shape in a region of the opposing surface corresponding to the power generation portion; an inflow portion provided at a first end portion in one direction of the mesh portion and configured to allow the reaction gas to flow into the mesh portion; an outflow portion provided at a second end portion of the mesh portion located on the opposite side of the first end portion in the one direction, and configured to allow the reaction gas to flow out of the mesh portion; and a suppression flow path constituting a portion of the mesh portion and configured so that a pressure loss when the reaction gas flows is greater than that in other portions of the mesh portion; The suppression flow path is arranged in the mesh portion so as to connect the inflow portion and the outflow portion with the shortest distance.

5. The fuel cell according to claim 4, wherein: The pair of separators have the same structure as each other.

6. The fuel cell according to claim 5, wherein: Each partition is formed into a rectangular shape, The mesh of the net-like portion is composed of polygonal ribs. The ribs extend obliquely relative to the sides of the partition.

7. A fuel cell comprising a power generation unit including a membrane electrode assembly and a pair of separators sandwiching the power generation unit. Each separator has an opposing surface facing the power generation portion, and a gas flow path configured to allow the reaction gas to flow is provided on the opposing surface. The gas flow path has: a mesh portion formed in a mesh shape in a region of the opposing surface corresponding to the power generation portion; an inflow portion provided at a first end portion in one direction of the mesh portion and configured to allow the reaction gas to flow into the mesh portion; an outflow portion provided at a second end portion of the mesh portion located on the opposite side of the first end portion in the one direction, and configured to allow the reaction gas to flow out of the mesh portion; and a suppression flow path constituting a portion of the mesh portion and configured so that a pressure loss when the reaction gas flows is greater than that in other portions of the mesh portion; The suppression flow path is arranged in the mesh portion so as to separate the inflow portion from the outflow portion.

8. The fuel cell according to claim 7, wherein: The pair of separators have the same structure as each other.

9. The fuel cell according to claim 8, wherein: Each partition is formed into a rectangular shape, The mesh of the net-like portion is composed of polygonal ribs. The ribs extend obliquely relative to the sides of the partition.

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