Fuel battery cell stack

Abstract

To provide a fuel battery cell stack that can reduce variations in the cooling effect of a cooling medium in fuel battery cells.SOLUTION: A fuel battery cell stack 13 has laminated therein a plurality of fuel battery cells 12 each having a power generation part, and a first separator and a second separator sandwiching the power generation part. The first separator is a meandering channel in which the flow direction of oxidant gas is reversed multiple times in a first channel 30. The second separator is a meandering channel in which the flow direction of fuel gas is reversed multiple times in a second channel 33. A cooling medium circulation area 34 in which a cooling medium circulates is formed between the first separator of one of the adjacent fuel battery cells 12 and the second separator of the other. General portions 36, 39 in both channels 30, 33 are wavy parts 37, 40 having a wave shape. Reversed portions 35, 38 of both channels 30, 33 extend so as to increase the circulation resistance of the cooling medium circulating areas corresponding to the reversed portions 35, 38 in the cooling medium circulation area 34.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fuel cell stack in which a plurality of fuel cells are stacked. [Background technology]

[0002] Conventionally, a known example of a fuel cell is shown in Patent Document 1. A plurality of fuel cells are stacked together for use as a fuel cell stack. A fuel cell is constructed by sandwiching a membrane electrode assembly between an anode side metal separator and a cathode side metal separator, and has an overall rectangular plate shape. An oxidant gas inlet passage for supplying oxidant gas and a fuel gas outlet passage for discharging fuel gas are provided at one end edge in the long side direction of the fuel cell.

[0003] A fuel gas inlet manifold for supplying fuel gas and an oxidant gas outlet manifold for discharging oxidant gas are provided at the other edge in the long side direction of the fuel cell. A coolant inlet manifold for supplying a coolant is provided at one edge in the short side direction of the fuel cell. A coolant outlet manifold for discharging the coolant is provided at the other edge in the short side direction of the fuel cell.

[0004] A fuel gas flow channel is formed on the surface of the anode-side metal separator facing the membrane electrode assembly by projections and recesses formed on both sides. The fuel gas flow channel communicates with a fuel gas inlet manifold and a fuel gas outlet manifold. The fuel gas flow channel has wavy flow grooves and an embossed portion. The fuel gas flow channel is configured as a serpentine flow channel as a whole by two turn-back partition members spaced apart from each other in the short side direction and arranged in a staggered pattern in the long side direction. The fuel gas flow channel has two turn-back portions, and embossed portions are provided corresponding to the two turn-back portions.

[0005] An oxidant gas flow channel is formed on the surface of the cathode-side metal separator facing the membrane electrode assembly by projections and recesses formed on both sides. The oxidant gas flow channel communicates with the oxidant gas inlet manifold and the oxidant gas outlet manifold. The oxidant gas flow channel has wavy flow grooves and an embossed portion. The oxidant gas flow channel is configured as a serpentine flow channel as a whole by two turn-back partition members spaced apart from each other in the short side direction and arranged in a staggered pattern in the long side direction. The oxidant gas flow channel has two turn-back portions, and embossed portions are provided corresponding to the two turn-back portions.

[0006] A coolant flow field communicating with the coolant inlet manifold and the coolant outlet manifold is formed extending in the short side direction between the anode side metal separator of one of the two fuel cells adjacent in the stacking direction and the cathode side metal separator of the other. That is, the coolant flow field is formed between the fuel gas flow field and the oxidant gas flow field. The coolant flows through the coolant flow field from the coolant inlet manifold side toward the coolant outlet manifold. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2006-147466 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the above-described fuel cell stack, the resistance of the cooling medium flowing through the cooling medium flow channel is greater in the region of the cooling medium flow channel that corresponds to the wavy flow grooves of each gas flow channel than in the region of the cooling medium flow channel that corresponds to the embossed portions of each gas flow channel. Therefore, the cooling medium flow channel has regions where the cooling medium flows easily and regions where the cooling medium flows poorly. This causes a problem of large variation in the cooling effect of the cooling medium in the fuel cell. [Means for solving the problem]

[0009] The means for solving the above problems and their effects will be described below. The fuel cell stack that solves the above problem is a fuel cell stack formed by stacking a plurality of plate-shaped fuel cells, each of which has a power generation section, and a first separator and a second separator sandwiching the power generation section, wherein the fuel cell has a fuel gas inlet through which fuel gas is supplied and an oxidant gas outlet through which oxidant gas is discharged formed at one end in a first direction, and a fuel gas outlet through which the fuel gas is discharged and an oxidant gas inlet through which the oxidant gas is supplied formed at the other end, or the fuel gas inlet and the oxidant gas inlet are formed at one end in the first direction, and the fuel gas outlet and the oxidant gas outlet are formed at the other end, and a cooling medium inlet through which a cooling medium is supplied and a cooling medium outlet through which the cooling medium is discharged formed at one end in a second direction perpendicular to the first direction, and the first separator has a surface on one side of the power generation section that is in contact with the oxidant gas inlet and the oxidant gas outlet. the second separator has integral unevenness on both sides that forms the multiple first flow paths for supplying the fuel gas as serpentine flow paths in which the flow direction of the oxidant gas is reversed multiple times, and the second separator has integral unevenness on both sides that forms the multiple second flow paths for supplying the fuel gas to a surface on the other side of the power generation unit between the fuel gas supply hole and the fuel gas discharge hole, the multiple second flow paths being serpentine flow paths in which the flow direction of the fuel gas is reversed multiple times, and a cooling medium flow region in which the cooling medium flows from the cooling medium supply hole side to the cooling medium discharge hole side is formed between the first separator of one of the two fuel cell cells adjacent in the stacking direction and the second separator of the other of the two fuel cell cells adjacent in the stacking direction, and at least a part of a general portion other than the reversed portions in at least one of the multiple first flow paths and the multiple second flow paths is a wavy portion that is wavy, and the reversed portions of the multiple first flow paths and the multiple second flow paths extend such that a flow resistance of the cooling medium flowing through a region corresponding to the reversed portion in the cooling medium flow region is large.

[0010] In general, the concaves and convexes forming the first flow paths of the first separator and the second flow paths of the second separator are inseparably linked, and therefore act as a flow resistance when the cooling medium flows through the cooling medium flow region. Since the first flow path and the second flow path are meandering flow paths, the general portion usually extends perpendicular to the flow direction of the cooling medium, and the inverted portion extends in the flow direction of the cooling medium. Therefore, the flow resistance when the cooling medium flows through the cooling medium flow region is greater in the region corresponding to the general portion than in the region corresponding to the inverted portion in the cooling medium flow region. Therefore, the cooling medium flow region has a region where the cooling medium flows easily and a region where the cooling medium flows poorly. As a result, there is a problem that the variation in the cooling effect of the cooling medium in the fuel cell is large.

[0011] In this regard, according to the above configuration, the inverted portions of the first flow paths and the second flow paths extend so as to increase the flow resistance of the cooling medium flowing through the area in the cooling medium flow region corresponding to the inverted portions. This makes it possible to reduce the difference in flow resistance when the cooling medium flows between the area in the cooling medium flow region corresponding to the inverted portions and the area in the cooling medium flow region corresponding to the general portion. This allows the cooling medium to flow in a balanced manner through the cooling medium flow region, thereby reducing the variation in the cooling effect of the cooling medium in the fuel cell. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view of a fuel cell according to an embodiment; [Diagram 2] FIG. 2 is an exploded perspective view showing a fuel cell. [Diagram 3] FIG. 2 is a plan view of a fuel cell stack. [Figure 4] FIG. 4 is an enlarged view of a main part of FIG. [Diagram 5] 4 is a cross-sectional view of projections and recesses that form a first flow path of a first separator and a second flow path of a second separator. FIG. [Figure 6]FIG. 10 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell stack in a modified example. [Figure 7] 13(a) to 13(c) are plan views showing an overlapping state of the first wavy portion and the second wavy portion in a modified example. [Figure 8] FIG. 10 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell stack in a modified example. [Figure 9] FIG. 10 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell stack in a modified example. [Figure 10] 13(a) to 13(c) are plan views showing modified examples in which the amplitude of the first wavy portion and the second wavy portion is changed. [Figure 11] 13(a) to 13(c) are plan views showing modified examples in which the wavelengths of the first wavy portion and the second wavy portion are changed. [Figure 12] 13 is a plan view of a first wavy portion and a second wavy portion in a modified example. FIG. [Figure 13] 13(a) to 13(e) are plan views of a first wavy portion and a second wavy portion in modified examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An embodiment will now be described with reference to the drawings. <Fuel cell 11> As shown in FIG. 1, the fuel cell 11 comprises a fuel cell stack 13 in which multiple rectangular plate-shaped fuel cells 12 that generate electricity are stacked in their thickness direction Z, and a pair of end plates 14 that sandwich the fuel cell stack 13 on either side of the fuel cell 12 in the thickness direction Z (stacking direction).

[0014] The pair of end plates 14 have their outer edges fastened to each other by a plurality of bolts 15 and a plurality of nuts 16, thereby compressing the fuel cell stack 13 in the thickness direction Z (stacking direction) of the fuel cell 12. Between each of the pair of end plates 14 and the fuel cell stack 13, there are interposed terminal plates (not shown) for collecting current and insulating plates (not shown) for providing insulation.

[0015] <Fuel cell 12> As shown in FIG. 2, the fuel cell 12 has a rectangular plate-shaped support frame 18 supporting a rectangular sheet-shaped power generation unit 17, a pair of rectangular sheet-shaped gas diffusion layers 19 sandwiching the power generation unit 17, and a pair of rectangular plate-shaped metal separators 20 sandwiching the support frame 18 supporting the power generation unit 17 sandwiched between the pair of gas diffusion layers 19.

[0016] Of the pair of separators 20, one disposed on the cathode side is a first separator 21, and the other disposed on the anode side is a second separator 22. The power generation section 17 is supported in a state housed in a rectangular opening 23 formed in the center of the support frame 18. The power generation section 17 is composed of a membrane electrode assembly (MEA).

[0017] In the following description, the long side direction, short side direction, and thickness direction of the fuel cell 12 are respectively referred to as a long side direction X as an example of a first direction, a short side direction Y as an example of a second direction, and a thickness direction Z. The long side direction X, the short side direction Y, and the thickness direction Z are perpendicular to each other.

[0018] <Flow path configuration in fuel cell 12> 2 and 3, of the two ends of the power generation unit 17 of the fuel cell 12 sandwiched in the long side direction X, a fuel gas supply hole 24 and an oxidant gas discharge hole 25 are formed at one end, and an oxidant gas supply hole 26 and a fuel gas discharge hole 27 are formed at the other end. The fuel gas supply hole 24 and the oxidant gas discharge hole 25 are both formed as elongated holes, and are arranged side by side in the short side direction Y.

[0019] The oxidant gas supply hole 26 and the fuel gas discharge hole 27 are both configured as long holes and are arranged side by side in the short side direction Y. A fuel gas containing, for example, hydrogen is supplied to the fuel gas supply hole 24. The fuel gas is discharged from the fuel gas discharge hole 27. An oxidant gas containing, for example, oxygen is supplied to the oxidant gas supply hole 26. The oxidant gas is discharged from the oxidant gas discharge hole 25.

[0020] The fuel gas inlet 24 and the oxygen-containing gas inlet 26 are arranged to face each other in the long side direction X. The oxygen-containing gas outlet 25 and the fuel gas outlet 27 are arranged to face each other in the long side direction X.

[0021] Of the two ends of the power generation section 17 of the fuel cell 12 sandwiched in the short side direction Y, a pair of cooling medium supply holes 28 are formed at one end, and a pair of cooling medium discharge holes 29 are formed at the other end. The pair of cooling medium supply holes 28 are both formed by elongated holes and are arranged side by side in the long side direction X. The pair of cooling medium discharge holes 29 are both formed by elongated holes and are arranged side by side in the long side direction X.

[0022] A cooling medium such as cooling water is supplied to the pair of cooling medium supply holes 28. The cooling medium is discharged from the pair of cooling medium discharge holes 29. The pair of cooling medium supply holes 28 and the pair of cooling medium discharge holes 29 are arranged to face each other in the short side direction Y.

[0023] The fuel gas supply hole 24, fuel gas discharge hole 27, oxidant gas supply hole 26, oxidant gas discharge hole 25, cooling medium supply hole 28, and cooling medium discharge hole 29 in the fuel cell 12 each form a manifold extending in the thickness direction Z (stacking direction) in the fuel cell stack 13.

[0024] <Separator 20> 2, 3, and 5, a plurality of first flow paths 30 that communicate between the oxidant gas supply hole 26 and the oxidant gas discharge hole 25 are formed on the surface of the first separator 21 facing the power generation section 17. The oxidant gas flows through each of the first flow paths 30, and the oxidant gas is supplied to one side of the surface of the power generation section 17 from the oxidant gas supply hole 26 to the oxidant gas discharge hole 25. Each of the first flow paths 30 is formed by an integral concavo-convex structure formed by pressing the first separator 21. The concavo-convex structure that constitutes each of the first flow paths 30 of the first separator 21 in this embodiment has a trapezoidal shape in cross section.

[0025] A recessed portion 31 on the power generation section 17 side of the unevenness of the first separator 21 constitutes a first flow path 30. The multiple recessed portions 31 constituting the multiple first flow paths 30 extend in parallel at regular intervals. Convex portions 32 are formed between the recessed portions 31 in the first separator 21. Regarding the unevenness of the first separator 21, the recessed portions 31 on one surface constitute the convex portions 32 on the other surface, and the convex portions 32 on one surface constitute the recessed portions 31 on the other surface.

[0026] The projections and recesses in the first separator 21 are arranged such that the recessed portions 31 and the protruding portions 32 are alternately arranged at equal intervals in the arrangement direction of the first flow paths 30. The first flow paths 30 in the first separator 21 extend in a meandering manner such that the flow direction of the oxidant gas reverses multiple times (twice in this example). In other words, the first flow paths 30 are so-called serpentine flow paths.

[0027] 2, 3, and 5, a plurality of second flow paths 33 that communicate between the fuel gas inlet 24 and the fuel gas outlet 27 are formed on the surface of the second separator 22 facing the power generation section 17. Each second flow path 33 allows fuel gas to flow and supplies the fuel gas to the other surface of the power generation section 17, that is, the surface opposite to the first separator 21, between the fuel gas inlet 24 and the fuel gas outlet 27. Each second flow path 33 is formed by an integral concavo-convex structure formed by pressing the second separator 22. The concavo-convex structure that constitutes each second flow path 33 of the second separator 22 in this embodiment has a trapezoidal shape in cross section.

[0028] A recessed portion 31 on the power generation section 17 side of the unevenness of the second separator 22 constitutes a second flow path 33. The multiple recessed portions 31 constituting the multiple second flow paths 33 extend in parallel at regular intervals. Convex portions 32 are formed between the recessed portions 31 in the second separator 22. Regarding the unevenness of the second separator 22, the recessed portions 31 on one surface constitute the convex portions 32 on the other surface, and the convex portions 32 on one surface constitute the recessed portions 31 on the other surface.

[0029] The projections and recesses in the second separator 22 are arranged such that the recessed portions 31 and the protruding portions 32 are alternately arranged at equal intervals in the arrangement direction of the second flow paths 33. The second flow paths 33 in the second separator 22 extend in a meandering manner such that the flow direction of the fuel gas reverses multiple times (twice in this example). In other words, the second flow paths 33 are so-called serpentine flow paths.

[0030] 2 to 4, the first separator 21 and the second separator 22 have the same configuration. In the fuel cell 12, the first separator 21 and the second separator 22 are arranged in a manner in which one is upside down relative to the other. In this case, when viewed from the thickness direction Z, the first separator 21 and the second separator 22 have their respective fuel gas inlet holes 24, fuel gas outlet holes 27, oxidant gas inlet holes 26, oxidant gas outlet holes 25, pairs of cooling medium inlet holes 28, and pairs of cooling medium outlet holes 29 overlap with each other.

[0031] <Fuel cell stack 13> 1 to 4, a cooling medium flow region 34 in which the cooling medium flows from the cooling medium supply hole 28 side toward the cooling medium discharge hole 29 side is formed between the first separator 21 of one of two fuel cells 12 adjacent to each other in the thickness direction Z (stacking direction) in the fuel cell stack 13 and the second separator 22 of the other fuel cell 12. Therefore, the flow direction F of the cooling medium in the cooling medium flow region 34 is the direction from the cooling medium supply hole 28 side toward the cooling medium discharge hole 29 side and is parallel to the short side direction Y.

[0032] The cooling medium flow region 34 is in contact with the unevenness that forms each of the first flow paths 30 of the first separator 21 and the unevenness that forms each of the second flow paths 33 of the second separator 22. Therefore, the unevenness that forms each of the first flow paths 30 of the first separator 21 and the unevenness that forms each of the second flow paths 33 of the second separator 22 affect the cooling medium flowing through the cooling medium flow region 34.

[0033] In each of the first flow paths 30 extending in a serpentine shape in the first separator 21, the portion where the flow of the oxidant gas is reversed is designated as a first reversal portion 35 as an example of a reversal portion, and the portion other than the first reversal portion 35 is designated as a first general portion 36 as an example of a general portion.

[0034] The first inverted portion 35 is linear and extends obliquely with respect to the flow direction F of the cooling medium so as to increase the flow resistance of the cooling medium flowing through a region in the cooling medium flow region 34 corresponding to the first inverted portion 35. The first general portion 36 extends in the long side direction X. The first general portion 36 forms a first wavy portion 37 as an example of a wavy portion having a wavy shape as a whole.

[0035] In each of the second flow paths 33 extending in a serpentine shape in the second separator 22, the portion where the flow of the fuel gas is reversed is designated as a second reversal portion 38 as an example of a reversal portion, and the portion other than the second reversal portion 38 is designated as a second general portion 39 as an example of a general portion.

[0036] The second inverted portion 38 is linear and extends obliquely with respect to the flow direction F of the cooling medium so as to increase the flow resistance of the cooling medium flowing through a region in the cooling medium flow region 34 corresponding to the second inverted portion 38. The second general portion 39 extends in the long side direction X. The second general portion 39 forms a second wavy portion 40 as an example of a wavy portion having a wavy shape as a whole.

[0037] When the first separator 21 and the second separator 22 are stacked in the thickness direction Z (stacking direction), the first wavy portion 37 of the first general portion 36 of each first flow path 30 and the second wavy portion 40 of the second general portion 39 of each second flow path 33 are out of phase with each other.

[0038] The first separator 21 and the second separator 22 extend such that the multiple first flow paths 30 of the first separator 21 and the multiple second flow paths 33 of the second separator 22 intersect with each other when viewed from the thickness direction Z. In this case, in the thickness direction Z, the multiple first flow paths 30 of the first separator 21 and the multiple second flow paths 33 of the second separator 22 are parallel to each other and do not overlap at all.

[0039] <Operation of the embodiment> 1 to 4, when an oxidant gas, a fuel gas, and a cooling medium are supplied to a fuel cell 11, power generation is performed in each fuel cell 12 constituting a fuel cell stack 13. When power generation is performed by the fuel cell 12, an oxidant gas is supplied from an oxidant gas supply hole 26, and a fuel gas is supplied from a fuel gas supply hole 24.

[0040] When the oxidant gas is supplied from each oxidant gas supply hole 26 in the fuel cell 12, the oxidant gas flows through each first flow path 30 to the oxidant gas discharge hole 25, and is diffused by the gas diffusion layer 19 while being supplied to the cathode side surface of the power generation section 17. The oxidant gas that has flowed to each oxidant gas discharge hole 25 is discharged to the outside of the fuel cell stack 13.

[0041] On the other hand, when fuel gas is supplied from each fuel gas supply hole 24 in the fuel cell 12, the fuel gas passes through each second flow passage 33 and flows to the fuel gas discharge hole 27, while being diffused by the gas diffusion layer 19 and supplied to the anode side surface of the power generation section 17. The fuel gas that has flowed to each fuel gas discharge hole 27 is discharged to the outside of the fuel cell stack 13.

[0042] At this time, in each fuel cell 12, electricity is generated based on an electrochemical reaction in the power generation section 17 between an oxidant gas supplied to the cathode side surface of the power generation section 17 and a fuel gas supplied to the anode side surface of the power generation section 17.

[0043] Each fuel cell 12 generates heat due to power generation caused by this electrochemical reaction. However, in a cooling medium flow region 34 formed between the first separator 21 of one of two adjacent fuel cells 12 in the fuel cell stack 13 and the second separator 22 of the other, the cooling medium flows from the cooling medium supply hole 28 toward the cooling medium discharge hole 29. This cools each fuel cell 12. The cooling medium that flows into the cooling medium discharge hole 29 is discharged to the outside of the fuel cell stack 13.

[0044] Generally, the projections and recesses forming the plurality of first flow paths 30 of the first separator 21 and the plurality of second flow paths 33 of the second separator 22 are inseparably connected, and therefore act as a flow resistance when the cooling medium flows through the cooling medium flow region 34. Since the first flow paths 30 and the second flow paths 33 are serpentine flow paths, the first general portion 36 and the second general portion 39 usually extend perpendicular to the flow direction F of the cooling medium, and the first inverted portion 35 and the second inverted portion 38 usually extend in the flow direction F of the cooling medium.

[0045] For this reason, the flow resistance when the cooling medium flows through the cooling medium flow region 34 is greater in the regions corresponding to the first general portion 36 and the second general portion 39 than in the regions corresponding to the first inverted portion 35 and the second inverted portion 38 in the cooling medium flow region 34. Therefore, in the cooling medium flow region 34, there are regions where the cooling medium flows easily and regions where the cooling medium flows poorly. As a result, there is a problem that the cooling effect of the cooling medium in the fuel cell 12 varies greatly.

[0046] In this regard, according to the present embodiment, the first inversion portions 35 of the multiple first flow paths 30 and the second inversion portions 38 of the multiple second flow paths 33 extend obliquely with respect to the flow direction F of the cooling medium so that the flow resistance of the cooling medium flowing through the areas corresponding to the first inversion portions 35 and the second inversion portions 38 in the cooling medium flow region 34 is increased.

[0047] This reduces the difference in flow resistance when the cooling medium flows between the regions in the cooling medium flow region 34 corresponding to the first inverted portion 35 and the second inverted portion 38 and the regions corresponding to the first general portion 36 and the second general portion 39. This allows the cooling medium to flow in a balanced manner in the cooling medium flow region 34, thereby reducing variation in the cooling effect of the cooling medium in the fuel cell 12.

[0048] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) In the fuel cell stack 13, the first inversion portions 35 of the multiple first flow paths 30 and the second inversion portions 38 of the multiple second flow paths 33 extend obliquely with respect to the flow direction F of the cooling medium so that the flow resistance of the cooling medium flowing through the areas corresponding to the first inversion portions 35 and the second inversion portions 38 in the cooling medium flow region 34 is large.

[0049] According to the above configuration, it is possible to reduce the difference in flow resistance when the cooling medium flows between the regions in the cooling medium flow region 34 corresponding to the first inverted portion 35 and the second inverted portion 38 and the regions corresponding to the first general portion 36 and the second general portion 39. Therefore, the cooling medium flows in a balanced manner in the cooling medium flow region 34, and therefore the variation in the cooling effect of the cooling medium in each fuel cell 12 can be reduced.

[0050] (2) In the fuel cell stack 13, the first general portion 36 of the first flow passage 30 and the second general portion 39 of the second flow passage 33 are entirely formed as the first wavy portion 37 and the second wavy portion 40, respectively. The first wavy portion 37 of the first flow passage 30 and the second wavy portion 40 of the second flow passage 33 are out of phase with each other when the first separator 21 and the second separator 22 are overlapped.

[0051] According to the above configuration, by shifting the phase between the first wavy portion 37 of the first flow path 30 and the second wavy portion 40 of the second flow path 33, the flow resistance of the cooling medium flowing through the area corresponding to the first general portion 36 of the first flow path 30 and the second general portion 39 of the second flow path 33 in the cooling medium flow region 34 can be changed compared to the case where the phase is not shifted.

[0052] (3) In the fuel cell stack 13, the first separator 21 and the second separator 22 have the same configuration. According to the above configuration, the first separator 21 and the second separator 22 can be the same part, and therefore the number of parts can be reduced compared to when the first separator 21 and the second separator 22 are different parts.

[0053] (4) In the fuel cell stack 13, the first separator 21 and the second separator 22 extend such that the multiple first flow paths 30 of the first separator 21 and the multiple second flow paths 33 of the second separator 22 intersect with each other when viewed in the thickness direction Z. In this case, in the thickness direction Z, the multiple first flow paths 30 of the first separator 21 and the multiple second flow paths 33 of the second separator 22 do not overlap at all while being parallel to each other.

[0054] According to the above configuration, when a fuel cell stack 13 is formed by stacking a plurality of fuel cells 12, the first flow paths 30 of the first separator 21 and the second flow paths 33 of the second separator 22 directly overlap each other, but also intersect each other. Therefore, even if the overlapping positions of the integral concaves and convexes forming the first flow paths 30 of the first separator 21 and the integral concaves and convexes forming the second flow paths 33 of the second separator 22 are slightly shifted, it is possible to prevent these concaves and convexes from fitting together. Therefore, even if the first separator 21 and the second separator 22 have the same configuration, it is possible to ensure the surface pressure between the fuel cell cells 12 when a fuel cell stack 13 is formed by stacking a plurality of fuel cells 12. As a result, the power generation performance of the fuel cell 11 can be maintained.

[0055] In this regard, when the recesses and protrusions on the first separator 21, which form the first flow paths 30, and the recesses and protrusions on the second separator 22, which form the second flow paths 33, are fitted together, the thickness of the fuel cells 12 stacked together at the fitted portion becomes thin. Therefore, when the fuel cells 12 are stacked together to form the fuel cell stack 13, the surface pressure between the fuel cells 12 cannot be ensured. As a result, the power generation performance of the fuel cell 11 is reduced.

[0056] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other as long as they are not technically inconsistent.

[0057] 6, the first inverted portions 35 of the plurality of first flow paths 30 and the second inverted portions 38 of the plurality of second flow paths 33 may extend in a wavy shape. In this way, the flow resistance of the cooling medium flowing through the regions in the cooling medium flow region 34 corresponding to the first inverted portions 35 and the second inverted portions 38 can be increased. Therefore, the difference in flow resistance when the cooling medium flows between the regions in the cooling medium flow region 34 corresponding to the first inverted portions 35 and the second inverted portions 38 and the regions in the cooling medium flow region 34 corresponding to the first general portion 36 and the second general portion 39 can be reduced.

[0058] 6, the first inverted portions 35 of the plurality of first flow paths 30 and the second inverted portions 38 of the plurality of second flow paths 33 may extend parallel to the flow direction F of the cooling medium in the cooling medium flow region 34. In this way, the flow resistance of the cooling medium flowing through the region corresponding to the first inverted portions 35 and the second inverted portions 38 in the cooling medium flow region 34 can be increased compared to the case where the first inverted portions 35 of the plurality of first flow paths 30 and the second inverted portions 38 of the plurality of second flow paths 33 are linear.

[0059] In the case of Figure 6 above, the amplitude of the first wavy inversion portion 35 and the second wavy inversion portion 38 may be larger or smaller than the amplitude of the first wavy portion 37 and the second wavy portion 40.

[0060] In the case of Figure 6 above, the wavelength of the first wavy inverted portion 35 and the second wavy inverted portion 38 may be longer or shorter than the wavelength of the first wavy portion 37 and the second wavy portion 40.

[0061] As shown in FIG. 7(a), the phase of the first wavy portion 37 of the first flow passage 30 and the second wavy portion 40 of the second flow passage 33 may be shifted by half a pitch. As shown in FIG. 7(b), the phase of the first wavy portion 37 of the first flow passage 30 and the second wavy portion 40 of the second flow passage 33 may be shifted by a quarter pitch.

[0062] As shown in FIG. 7(c), the phase of the first wavy portion 37 of the first flow passage 30 and the second wavy portion 40 of the second flow passage 33 may be shifted by one-third pitch. As shown in FIG. 8, half (a part) of the first general portions 36 of the plurality of first flow paths 30 and the second general portions 39 of the plurality of second flow paths 33 may be straight.

[0063] As shown in FIG. 9 , the straight-lined portions of the first general portions 36 of the first flow paths 30 and the straight-lined portions of the second general portions 39 of the second flow paths 33 in FIG. 8 may extend obliquely with respect to the long-side direction X.

[0064] As shown in Figures 10(a), 10(b), and 10(c), the amplitude of the first wavy portion 37 and the second wavy portion 40 may be changed as appropriate. Of Figures 10(a), 10(b), and 10(c), the amplitude of the first wavy portion 37 and the second wavy portion 40 is the smallest in Figure 10(a) and the largest in Figure 10(c).

[0065] As shown in Figures 11(a), 11(b), and 11(c), the wavelengths of the first wavy portion 37 and the second wavy portion 40 may be changed as appropriate. Of Figures 11(a), 11(b), and 11(c), the wavelengths of the first wavy portion 37 and the second wavy portion 40 are the longest in Figure 11(a) and the shortest in Figure 11(c).

[0066] As shown in FIG. 12, the amplitude of the first wavy portion 37 and the second wavy portion 40 may be gradually decreased or gradually increased. As shown in FIG. 13(a), the first wavy portion 37 and the second wavy portion 40 may be trapezoidal in shape.

[0067] As shown in FIG. 13(b), the first wavy portion 37 and the second wavy portion 40 may be formed in a zigzag shape. As shown in FIG. 13(c), the first wavy portion 37 and the second wavy portion 40 may be V-shaped.

[0068] As shown in FIG. 13(d), the first wavy portion 37 and the second wavy portion 40 may be W-shaped. 13(e), the first wavy portion 37 and the second wavy portion 40 may be formed in a zigzag shape, with narrow portions 41 and wide portions 42 that are wider than the narrow portions 41 being arranged alternately. In this way, the oxidant gas and the fuel gas can easily enter the gas diffusion layer 19 from the first wavy portion 37 and the second wavy portion 40, respectively.

[0069] The shapes of FIGS. 13(a) to 13(e) may be applied to the first inverted portion 35 and the second inverted portion 38 in FIG. The first separator 21 and the second separator 22 may have different configurations.

[0070] The first general portion 36 of the first flow path 30 and the second general portion 39 of the second flow path 33 may each have a portion that is a first wavy portion 37 and a second wavy portion 40. The first wavy portion 37 of the first flow path 30 and the second wavy portion 40 of the second flow path 33 do not necessarily need to be out of phase with each other when the first separator 21 and the second separator 22 are overlapped.

[0071] Either the first general portion 36 of the first flow passage 30 or the second general portion 39 of the second flow passage 33 may be linear. The positions of the oxidizing gas discharge holes 25 and the oxidizing gas supply holes 26 may be interchanged.

[0072] The positions of the fuel gas supply holes 24 and the fuel gas discharge holes 27 may be interchanged. <Additional Notes> The above embodiment includes the configurations described in the following supplementary notes.

[0073] [Appendix 1] A fuel cell stack formed by stacking a plurality of plate-shaped fuel cells each having a power generation section, and a first separator and a second separator sandwiching the power generation section, wherein the fuel cell has a fuel gas inlet through which a fuel gas is supplied and an oxidant gas outlet through which an oxidant gas is discharged formed at one end in a first direction, and a fuel gas outlet through which the fuel gas is discharged and an oxidant gas inlet through which the oxidant gas is supplied formed at the other end, or the fuel gas inlet and the oxidant gas inlet are formed at one end in the first direction, and the fuel gas outlet and the oxidant gas outlet are formed at the other end, and a cooling medium inlet through which a cooling medium is supplied and a cooling medium outlet through which the cooling medium is discharged formed at one end in a second direction perpendicular to the first direction, and the first separator has a plurality of first flow channels for supplying the oxidant gas to a surface on one side of the power generation section between the oxidant gas inlet and the oxidant gas outlet. the second separator has integral unevenness on both sides forming a plurality of second flow paths that supply the fuel gas to a surface on the other side of the power generation unit between the fuel gas supply hole and the fuel gas discharge hole, as a serpentine flow path in which the flow direction of the fuel gas is reversed a plurality of times; a cooling medium flow region in which the cooling medium flows from the cooling medium supply hole side to the cooling medium discharge hole side is formed between the first separator of one of the two fuel cell cells adjacent in the stacking direction and the second separator of the other of the two fuel cell cells adjacent in the stacking direction, and at least a part of a general portion other than the reversal portions in at least one of the plurality of first flow paths and the plurality of second flow paths is a wavy portion that is wavy, and the reversal portions of the plurality of first flow paths and the plurality of second flow paths extend such that a flow resistance of the cooling medium flowing through a region corresponding to the reversal portion in the cooling medium flow region is large.

[0074] [Appendix 2] The fuel cell stack according to [Appendix 1], wherein the inverted portion extends obliquely with respect to a flow direction of the cooling medium in the cooling medium flow region. [Appendix 3] The fuel cell stack according to [Appendix 1] or [Appendix 2], wherein the inverted portion extends in a wavy manner.

[0075] [Appendix 4] A fuel cell stack according to any one of [Appendix 1] to [Appendix 3], characterized in that the general portions of both the first flow path and the second flow path are entirely made of the wavy portion, and the wavy portion of the first flow path and the wavy portion of the second flow path are out of phase with each other when the first separator and the second separator are stacked together.

[0076] [Appendix 5] The fuel cell stack according to any one of [Appendix 1] to [Appendix 4], wherein the first separator and the second separator have the same configuration. [Explanation of symbols]

[0077] 11...fuel cell 12...Fuel cell 13...Fuel cell stack 14…End plate 15…Volts 16…Nut 17…Power generation section 18…Support frame 19...Gas diffusion layer 20…Separator 21…First separator 22…Second separator 23…Opening 24...Fuel gas supply hole 25...Oxidant gas exhaust hole 26...Oxidant gas supply hole 27...Fuel gas exhaust hole 28…Cooling medium supply hole 29…Cooling medium discharge hole 30…First flow path 31...Concave portion that constitutes the unevenness 32...Convex parts that make up the unevenness 33…Second flow path 34…Cooling medium distribution area 35...First inverted portion as an example of an inverted portion 36...First general part as an example of a general part 37...First wavy portion as an example of a wavy portion 38...Second inverted portion as an example of an inverted portion 39...Second general part as an example of a general part 40...Second wavy portion as an example of a wavy portion 41…Narrow part 42…Wide section F…Flow direction X: Long side direction as an example of the first direction Y: Short side direction as an example of the second direction Z: Thickness direction

Claims

1. A fuel cell stack formed by stacking a plurality of plate-shaped fuel cells, each of which has a power generation section and a first separator and a second separator sandwiching the power generation section, the fuel cell has a fuel gas supply hole through which fuel gas is supplied and an oxidant gas discharge hole through which oxidant gas is discharged formed at one end in a first direction, and a fuel gas discharge hole through which the fuel gas is discharged and an oxidant gas supply hole through which the oxidant gas is supplied formed at the other end, or the fuel gas supply hole and the oxidant gas supply hole are formed at one end in the first direction, and the fuel gas discharge hole and the oxidant gas discharge hole are formed at the other end, and a cooling medium supply hole through which a cooling medium is supplied and a cooling medium discharge hole through which the cooling medium is discharged formed at one end in a second direction perpendicular to the first direction, the first separator has a plurality of first flow paths for supplying the oxidant gas to a surface on one side of the power generation section between the oxidant gas supply hole and the oxidant gas discharge hole, the first separator having an integral concavo-convex shape that forms the first flow paths as meandering flow paths in which a flow direction of the oxidant gas is reversed a plurality of times, the second separator has a plurality of second flow paths that supply the fuel gas to the other side of the power generation section between the fuel gas supply hole and the fuel gas exhaust hole, the second separator having an integral concavo-convex surface that forms the second flow paths as meandering flow paths in which the flow direction of the fuel gas is reversed a plurality of times, a cooling medium flow region in which the cooling medium flows from the cooling medium supply hole side to the cooling medium discharge hole side is formed between the first separator of one of the two fuel cell units adjacent in the stacking direction and the second separator of the other of the two fuel cell units adjacent in the stacking direction, At least a part of a general portion other than the inverted portion in at least one of the plurality of first flow paths and the plurality of second flow paths is a wavy portion having a wavy shape, a fuel cell stack comprising: a first flow path and a second flow path, the first flow path and the second flow path being arranged in a first direction and a second direction, the first flow path and the second flow path being arranged in a second direction;

2. 2. The fuel cell stack according to claim 1, wherein the inverted portion extends obliquely with respect to a flow direction of the cooling medium in the cooling medium flow region.

3. 3. The fuel cell stack according to claim 1, wherein the inverted portion extends in a wavy manner.

4. the general portion of both the first flow path and the second flow path is entirely within the corrugated portion; 3. The fuel cell stack according to claim 1, wherein the wavy portion of the first flow path and the wavy portion of the second flow path are out of phase with each other when the first separator and the second separator are stacked.

5. 3. The fuel cell stack according to claim 1, wherein the first separator and the second separator have the same configuration.

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