Fuel cell stack

Abstract

The present invention provides a fuel cell cell stack that can reduce variations in the cooling effect due to the cooling medium in a fuel cell. [Solution] The fuel cell stack 13 is constructed by stacking multiple fuel cell cells 12, each having a power generation section and a first separator and a second separator sandwiching the power generation section. The first separator has a meandering first flow path 30 in which the flow direction of the oxidizer gas reverses multiple times. The second separator has a meandering second flow path 33 in which the flow direction of the fuel gas reverses multiple times. A cooling medium flow region 34 is formed between the first separator of one of the adjacent fuel cell cells 12 and the second separator of the other, through which the cooling medium flows. The first reversal portion 35 and the second reversal portion 38 of the first flow path 30 and the second flow path 33, respectively, extend inclined with respect to the short side direction Y and overlap so as to intersect between a cooling medium supply hole 28 and a cooling medium discharge hole 25 that are opposite each other in the long side direction X when viewed from the thickness direction Z.

Description

Technical Field

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

Background Art

[0002] Conventionally, as a fuel cell stack, for example, the one shown in Patent Document 1 is known. Such a fuel cell stack is formed by stacking a plurality of fuel cells. A fuel cell is configured by sandwiching an electrolyte membrane / electrode structure between an anode-side metal separator and a cathode-side metal separator, and is rectangular plate-shaped as a whole.

[0003] At one edge portion in the long side direction of the fuel cell, there are provided an oxidant gas inlet communication hole for supplying an oxidant gas, a cooling medium outlet communication hole for discharging a cooling medium, and a fuel gas outlet communication hole for discharging a fuel gas. At the other edge portion in the long side direction of the fuel cell, there are provided a fuel gas inlet communication hole for supplying a fuel gas, a cooling medium inlet communication hole for supplying a cooling medium, and an oxidant gas outlet communication hole for discharging an oxidant gas.

[0004] On the surface of the anode-side metal separator on the side of the electrolyte membrane / electrode structure, a fuel gas flow path is formed by the unevenness of the front and back being integrated. The fuel gas flow path communicates with the fuel gas inlet communication hole and the fuel gas outlet communication hole. The fuel gas flow path constitutes a serpentine flow path having two folded portions linearly extending in the short side direction of the fuel cell.

[0005] On the surface of the cathode-side metal separator on the side of the electrolyte membrane / electrode structure, an oxidant gas flow path is formed by the unevenness of the front and back being integrated. The oxidant gas flow path communicates with the oxidant gas inlet communication hole and the oxidant gas outlet communication hole. The oxidant gas flow path constitutes a serpentine flow path having two folded portions linearly extending in the short side direction of the fuel cell.

[0006] Between the anode-side metal separator of one of two fuel cell cells adjacent to each other in the stacking direction and the cathode-side metal separator of the other, a cooling medium flow region is formed, through which the cooling medium flows, communicating with a cooling medium inlet communication hole and a cooling medium outlet communication hole that are opposite each other in the long-side direction. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2010-55857 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Incidentally, in the fuel cell cell stack described above, the folded portion of the fuel gas flow path of one anode-side metal separator and the folded portion of the oxidizer gas flow path of the cathode-side metal separator of two adjacent fuel cell cells in the stacking direction overlap each other. That is, the folded portions of the fuel gas flow path and the oxidizer gas flow path, formed by the irregularities, overlap each other in a parallel manner, extending linearly in the short-side direction between the cooling medium inlet communication hole and the cooling medium outlet communication hole in the cooling medium flow region.

[0009] Therefore, the cooling medium becomes difficult to flow between the cooling medium inlet communication hole and the cooling medium outlet communication hole in the cooling medium flow region. In other words, the cooling medium flow region has areas where the cooling medium flows easily and areas where it flows difficult. Consequently, there is a problem in that the cooling effect of the cooling medium in the fuel cell becomes more variable. [Means for solving the problem]

[0010] The following describes the means and effects of solving the above problems. A fuel cell cell stack that solves the above problems is a fuel cell cell stack formed by stacking a plurality of rectangular plate-shaped fuel cell cells, each having a power generation section, a first separator and a second separator sandwiching the power generation section, and mutually orthogonal first and second sides, wherein the fuel cell cell has a first hole, a second hole and a third hole formed at one end in the first direction, which is the direction in which the first side extends, and a fourth hole, a fifth hole and a sixth hole formed at the other end, and the first hole, the second hole and the third hole are on the second side In the second direction of extension, the holes are arranged in this order from one side to the other, and the fourth, fifth, and sixth holes are arranged in this order from one side to the other in the second direction, and of the first and sixth holes, one is a fuel gas supply hole into which fuel gas is supplied and the other is a fuel gas discharge hole into which the fuel gas is discharged, and of the third and fourth holes, one is an oxidant gas supply hole into which oxidant gas is supplied and the other is an oxidant gas discharge hole into which the oxidant gas is discharged The first separator has a front and back surface with irregularities that form a plurality of first flow channels on one side of the power generation section between the oxidant gas supply hole and the oxidant gas discharge hole, which supply the oxidant gas as a meandering flow channel in which the flow direction of the oxidant gas reverses multiple times, and the second separator is located between the fuel gas supply hole and the fuel gas discharge hole and the power generation section The other side of the fuel cell has a series of second flow channels for supplying the fuel gas, which are formed as meandering flow channels in which the direction of fuel gas flow reverses multiple times, and a cooling medium flow region 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, through which the cooling medium flows from the cooling medium supply hole side toward the cooling medium discharge hole side, and the reversed portions of the series of first flow channels and series of second flow channels extend inclined with respect to the second direction,The gist of this is that, when viewed from the stacking direction, the cooling medium supply hole and the cooling medium discharge hole, which are opposite each other in the first direction, overlap so as to intersect.

[0011] Generally, the irregularities forming the multiple first channels of the first separator and the multiple second channels of the second separator are inseparable, and therefore create flow resistance when the cooling medium flows through the cooling medium flow region. Since the first and second channels are meandering channels, the general portion extends in the first direction and the reversed portion extends in the second direction. In this case, the cooling medium attempts to flow through the cooling medium flow region from the cooling medium supply hole to the cooling medium discharge hole. However, when the multiple first channels and multiple second channels are parallel and the irregularities in their reversed portions overlap between the cooling medium supply hole and the cooling medium discharge hole in the cooling medium flow region, the cooling medium will not flow to the portion where the irregularities overlap. As a result, there is a problem in that the cooling effect of the cooling medium in the fuel cell cell becomes more variable.

[0012] In this regard, according to the above configuration, the inverted portions of each of the multiple first channels and the multiple second channels extend inclined with respect to the second direction and overlap so as to intersect between the cooling medium supply hole and the cooling medium discharge hole that are opposite each other in the first direction when viewed from the stacking direction. Therefore, the irregularities in the inverted portions of the multiple first channels and the multiple second channels do not overlap in a parallel state between the cooling medium supply hole and the cooling medium discharge hole in the cooling medium flow region. As a result, the flow of the cooling medium from the cooling medium supply hole to the cooling medium discharge hole in the cooling medium flow region is not obstructed. In addition, the inverted portions of each of the multiple first channels and the multiple second channels guide a portion of the cooling medium supplied from the cooling medium supply hole to both sides of the second direction in the cooling medium flow region. Therefore, the cooling medium flows through the cooling medium flow region in a balanced manner, which reduces variations in the cooling effect of the cooling medium in the fuel cell cell. [Brief explanation of the drawing]

[0013] [Figure 1]This is a schematic cross-sectional view of a fuel cell according to one embodiment. [Figure 2] This is an exploded perspective view showing a fuel cell. [Figure 3] This is a plan view of a fuel cell stack. [Figure 4] This is a cross-sectional view of the irregularities that constitute the first channel of the first separator and the second channel of the second separator. [Figure 5] This is a plan view of the modified fuel cell cell stack. [Figure 6] This is a plan view of a fuel cell cell stack in another modified example. [Modes for carrying out the invention]

[0014] One embodiment will be described below with reference to the drawings. <Fuel cell 11> As shown in Figure 1, the fuel cell 11 comprises a fuel cell cell stack 13 formed by stacking multiple rectangular plate-shaped fuel cell cells 12 that generate electricity in the thickness direction Z, and a pair of end plates 14 that sandwich the fuel cell cell stack 13 from both sides in the thickness direction Z of the fuel cell cells 12. In this example, the thickness direction Z of the fuel cell cells 12 coincides with the stacking direction of the fuel cell cells 12.

[0015] The pair of end plates 14 are fastened together at their outer edges by a plurality of bolts 15 and a plurality of nuts 16, thereby pressing the fuel cell cell stack 13 in the thickness direction Z of the fuel cell cell 12. Between the pair of end plates 14 and the fuel cell cell stack 13, there are interposed terminal plates (not shown) for collecting current and insulating plates (not shown) for insulation.

[0016] <Fuel cell cell 12> As shown in FIG. 2, the fuel cell 12 has a rectangular plate-shaped support frame 18 in a state of supporting a power generation part 17 having a rectangular sheet shape, a pair of gas diffusion layers 19 having a rectangular sheet shape sandwiching the power generation part 17, and a pair of rectangular plate-shaped metal separators 20 sandwiching the support frame 18 in a state of supporting the power generation part 17 sandwiched by the pair of gas diffusion layers 19.

[0017] Of the pair of separators 20, one disposed on the cathode side is the first separator 21, and the other disposed on the anode side is the second separator 22. The power generation part 17 is supported in a state of being accommodated in a rectangular opening 23 formed in the central part of the support frame 18. The power generation part 17 is composed of a membrane electrode assembly (MEA: Membrane Electrode Assembly).

[0018] In this example, the first side and the second side orthogonal to each other in the rectangular plate-shaped fuel cell 12 are the long side and the short side, respectively. In the following description, the long side direction, the short side direction, and the thickness direction in the fuel cell 12 are the long side direction X as an example of the first direction in which the long side extends, the short side direction Y as an example of the second direction in which the short side extends, and the thickness direction Z, respectively. The long side direction X, the short side direction Y, and the thickness direction Z are directions orthogonal to each other.

[0019] <Flow path configuration in the fuel cell 12> As shown in FIGS. 2 and 3, at one end of the fuel cell 12 in the long side direction X, there are formed a fuel gas supply hole 24 as an example of the first hole for supplying fuel gas, a cooling medium discharge hole 25 as an example of the second hole for discharging the cooling medium, and an oxidant gas discharge hole 26 as an example of the third hole for discharging the oxidant gas. The fuel gas supply hole 24, the cooling medium discharge hole 25, and the oxidant gas discharge hole 26 are arranged side by side in this order from one side to the other side in the short side direction Y of the fuel cell 12.

[0020] At the other end of the fuel cell 12 in the long side direction X, there are formed an oxidant gas supply hole 27 as an example of a fourth hole for supplying an oxidant gas, a cooling medium supply hole 28 as an example of a fifth hole for supplying a cooling medium, and a fuel gas discharge hole 29 as an example of a sixth hole for discharging a fuel gas. The oxidant gas supply hole 27, the cooling medium supply hole 28, and the fuel gas discharge hole 29 are arranged side by side in this order from one side to the other side in the short side direction Y of the fuel cell 12.

[0021] For example, a fuel gas containing hydrogen is supplied to the fuel gas supply hole 24. The fuel gas is discharged from the fuel gas discharge hole 29. For example, an oxidant gas containing oxygen is supplied to the oxidant gas supply hole 27. The oxidant gas is discharged from the oxidant gas discharge hole 26. For example, a cooling medium such as cooling water is supplied to the cooling medium supply hole 28. The cooling medium is discharged from the cooling medium discharge hole 25.

[0022] The fuel gas supply hole 24 and the oxidant gas supply hole 27 are arranged to face each other in the long side direction X. The oxidant gas discharge hole 26 and the fuel gas discharge hole 29 are arranged to face each other in the long side direction X. The cooling medium discharge hole 25 and the cooling medium supply hole 28 are arranged to face each other in the long side direction X.

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

[0024] <Separator 20> As shown in Figures 2 to 4, a plurality of first flow channels 30 are formed on the side of the first separator 21 facing the power generation section 17, connecting an oxidant gas supply hole 27 and an oxidant gas discharge hole 26. Oxidant gas flows through each first flow channel 30, and the oxidant gas is supplied to one side of the power generation section 17 between the oxidant gas supply hole 27 and the oxidant gas discharge hole 26. Each first flow channel 30 is composed of a single, integrated surface with protrusions and recesses formed by press-forming the first separator 21. In this embodiment, the protrusions and recesses constituting each first flow channel 30 of the first separator 21 have a trapezoidal shape in cross-sectional view.

[0025] The recessed portion 31 on the power generation section 17 side of the uneven surface of the first separator 21 constitutes the first flow path 30. The multiple recessed portions 31 that constitute the multiple first flow paths 30 extend in parallel at regular intervals. Protruding portions 32 are formed between the recessed portions 31 of the first separator 21. The uneven surface of the first separator 21 is such that the recessed portion 31 on one surface constitutes the protruding portion 32 on the other surface, and the protruding portion 32 on one surface constitutes the recessed portion 31 on the other surface.

[0026] The irregularities in the first separator 21 are arranged such that the recessed portions 31 and the convex portions 32 are alternately spaced at equal intervals in the direction in which the multiple first flow channels 30 are aligned. The multiple first flow channels 30 in the first separator 21 extend in a meandering manner so that the flow direction of the oxidizing gas reverses multiple times (twice in this example). In other words, the multiple first flow channels 30 form a so-called serpentine-type flow channel.

[0027] As shown in Figures 2 to 4, the second separator 22 has a plurality of second flow paths 33 formed on the side facing the power generation unit 17, connecting a fuel gas supply hole 24 and a fuel gas discharge hole 29. Fuel gas flows through each second flow path 33, and between the fuel gas supply hole 24 and the fuel gas discharge hole 29, fuel gas is supplied to the other side of the power generation unit 17, which is the side opposite to the first separator 21. Each second flow path 33 is formed by a single set of irregularities on both sides of the second separator 22, which is created by press-forming the second separator 22. In this embodiment, the irregularities constituting each second flow path 33 of the second separator 22 have a trapezoidal shape in cross-sectional view.

[0028] The recessed portion 31 on the power generation section 17 side of the irregularities of the second separator 22 constitutes the second flow path 33. The multiple recessed portions 31 that constitute the multiple second flow paths 33 extend in parallel at regular intervals. Protruding portions 32 are formed between the recessed portions 31 of the second separator 22. The irregularities of the second separator 22 are such that the recessed portion 31 on one surface constitutes the protruding portion 32 on the other surface, and the protruding portion 32 on one surface constitutes the recessed portion 31 on the other surface.

[0029] The irregularities in the second separator 22 are arranged such that the recessed portion 31 and the convex portion 32 are alternately spaced at equal intervals in the direction in which the multiple second flow channels 33 are aligned. The multiple second flow channels 33 in the second separator 22 extend in a meandering manner so that the direction of fuel gas flow reverses multiple times (twice in this example). In other words, the multiple second flow channels 33 form a so-called serpentine-type flow channel.

[0030] As shown in Figures 2 and 3, the first separator 21 and the second separator 22 have identical configurations. In the fuel cell cell 12, the first separator 21 and the second separator 22 are arranged such that one is reversed relative to the other. In this case, when viewed from the thickness direction Z, the fuel gas supply holes 24, fuel gas discharge holes 29, oxidizer gas supply holes 27, oxidizer gas discharge holes 26, cooling medium supply holes 28, and cooling medium discharge holes 25 of the first separator 21 and the second separator 22 overlap.

[0031] <Fuel cell stack 13> As shown in Figures 1 to 3, in the fuel cell cell stack 13, a cooling medium flow region 34 is formed between the first separator 21 of one of the two adjacent fuel cell cells 12 in the thickness direction Z (stacking direction) and the second separator 22 of the other, through which the cooling medium flows from the cooling medium supply hole 28 side toward the cooling medium discharge hole 25 side.

[0032] The cooling medium flow region 34 is in contact with the irregularities forming each of the first flow channels 30 of the first separator 21 and the irregularities forming each of the second flow channels 33 of the second separator 22. Therefore, the irregularities forming each of the first flow channels 30 of the first separator 21 and the irregularities forming each of the second flow channels 33 of the second separator 22 affect the flow of the cooling medium in the cooling medium flow region 34.

[0033] In each of the serpentine-shaped first flow channels 30 in the first separator 21, the portion where the flow of the oxidizing gas reverses is designated as a first reversal portion 35, which is an example of a reversal portion, while the portion other than the first reversal portion 35 is designated as a first general portion 36, which is an example of a general portion. The first reversal portion 35 extends in a straight line at an angle to the short side direction Y.

[0034] In this case, the first inverted portion 35 extends inclined with respect to the short side direction Y such that one end in the short side direction Y is located on one side of the long side direction X than the other end in the short side direction Y. The inclination angle of the first inverted portion 35 with respect to the short side direction Y is preferably acute, and more preferably 45° or less. The first general portion 36 extends in the long side direction X. The first general portion 36 is a first wavy portion 37, which is an example of a wavy portion whose entire structure is wavy.

[0035] In each serpentine-shaped second flow path 33 of the second separator 22, the portion where the fuel gas flow reverses is designated as a second reversal portion 38, which is an example of a reversal portion, while the portion other than the second reversal portion 38 is designated as a second general portion 39, which is an example of a general portion. The second reversal portion 38 extends in a straight line at an angle to the short side direction Y.

[0036] In this case, the second inverted portion 38 extends inclined with respect to the short side direction Y such that one end in the short side direction Y is located on the other side of the long side direction X than the other end in the short side direction Y. The inclination angle of the second inverted portion 38 with respect to the short side direction Y is preferably acute, and more preferably 45° or less. The second general portion 39 extends in the long side direction X. The second general portion 39 is a second wavy portion 40, which is an example of a wavy portion whose entire structure is wavy.

[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 channel 30 and the second wavy portion 40 of the second general portion 39 of each second channel 33 overlap in such a way that their phases are offset from each other in the long side direction X. In this example, the phase of the first wavy portion 37 and the phase of the second wavy portion 40 are offset from each other by half a pitch in the long side direction X.

[0038] The first inversion portions 35 of the multiple first flow channels 30 of the first separator 21 and the second inversion portions 38 of the multiple second flow channels 33 of the second separator 22 overlap so that they partially intersect between the cooling medium supply holes 28 and the cooling medium discharge holes 25, which are opposite each other in the long side direction X when viewed from the thickness direction Z (stacking direction). In this case, in the thickness direction Z, there are no overlapping portions at all between the multiple first flow channels 30 of the first separator 21 and the multiple second flow channels 33 of the second separator 22, while they are parallel to each other.

[0039] <Operation of the Embodiment> As shown in Figures 1 to 3, when oxidizer gas, fuel gas, and cooling medium are supplied to the fuel cell 11, power is generated in each fuel cell cell 12 that makes up the fuel cell cell stack 13. When power is generated by the fuel cell cells 12, oxidizer gas is supplied from the oxidizer gas supply port 27 and fuel gas is supplied from the fuel gas supply port 24.

[0040] When oxidant gas is supplied to the fuel cell cell 12 from each oxidant gas supply port 27, the oxidant gas is supplied to the cathode side of the power generation unit 17 while being diffused by the gas diffusion layer 19 as it flows through each first flow path 30 to the oxidant gas discharge port 26. The oxidant gas that has flowed to each oxidant gas discharge port 26 is discharged to the outside of the fuel cell cell stack 13.

[0041] On the other hand, when fuel gas is supplied to the fuel cell cell 12 from each fuel gas supply port 24, the fuel gas is supplied to the anode side of the power generation unit 17 while being diffused by the gas diffusion layer 19 as it flows through each second flow path 33 to the fuel gas discharge port 29. The fuel gas that has flowed to each fuel gas discharge port 29 is discharged to the outside of the fuel cell cell stack 13.

[0042] In this case, each fuel cell cell 12 generates electricity based on an electrochemical reaction in the power generation unit 17 between the oxidizer gas supplied to the cathode side of the power generation unit 17 and the fuel gas supplied to the anode side of the power generation unit 17.

[0043] Each fuel cell 12 generates heat through the electrochemical reaction that produces electricity. However, a cooling medium is supplied from a cooling medium supply hole 28 to the cooling medium circulation region 34 formed between the first separator 21 of one of the two adjacent fuel cell cells 12 in the fuel cell stack 13 and the second separator 22 of the other.

[0044] Here, as shown in Figure 3, generally, the cooling medium supplied from the cooling medium supply hole 28 to the cooling medium flow region 34 tends to flow straight through the cooling medium flow region 34 from the cooling medium supply hole 28 to the cooling medium discharge hole 25. At this time, one end of two first reversal portions 35 of the multiple first flow paths 30 of the first separator 21 and one end of two second reversal portions 38 of the multiple second flow paths 33 of the second separator 22 overlap so as to intersect between the cooling medium supply hole 28 and the cooling medium discharge hole 25.

[0045] Furthermore, at this time, the first inversion portion 35 extends from between the cooling medium supply hole 28 and the cooling medium discharge hole 25 to between the fuel gas discharge hole 29 and the oxidizer gas discharge hole 26, while the second inversion portion 38 extends from between the cooling medium supply hole 28 and the cooling medium discharge hole 25 to between the oxidizer gas supply hole 27 and the fuel gas supply hole 24.

[0046] Therefore, a portion of the cooling medium that would otherwise flow straight through the cooling medium flow region 34 from the cooling medium supply hole 28 to the cooling medium discharge hole 25 is guided by the first reversal section 35 to the space between the fuel gas discharge hole 29 and the oxidizer gas discharge hole 26, and by the second reversal section 38 to the space between the oxidizer gas supply hole 27 and the fuel gas supply hole 24.

[0047] As a result, in the cooling medium flow region 34, a flow of cooling medium is formed from the cooling medium supply hole 28 toward the cooling medium discharge hole 25, a flow of cooling medium toward the oxidizer gas discharge hole 26 between the fuel gas discharge hole 29 and the oxidizer gas discharge hole 26, and a flow of cooling medium toward the fuel gas supply hole 24 between the oxidizer gas supply hole 27 and the fuel gas supply hole 24.

[0048] In other words, the cooling medium flows through the cooling medium flow region 34, distributing in the short-side direction Y from the cooling medium supply hole 28 towards the cooling medium discharge hole 25. This means that the cooling medium flows evenly throughout the entire cooling medium flow region 34. As a result, the entire fuel cell cell 12 is cooled evenly by the cooling medium. Therefore, variations in the cooling effect of the cooling medium in the fuel cell cell 12 are reduced. The cooling medium that flows to each cooling medium discharge hole 25 is discharged to the outside of the fuel cell cell stack 13.

[0049] <Effects of the Embodiment> According to the embodiments described in detail above, the following effects are achieved. (1) The fuel cell stack 13 is formed by stacking multiple rectangular plate-shaped fuel cell cells 12, each having a power generation unit 17, a first separator 21 and a second separator 22 flanking the power generation unit 17, and mutually orthogonal first and second sides. The fuel cell cell 12 has a fuel gas supply hole 24 for supplying fuel gas, a cooling medium discharge hole 25 for discharging cooling medium, and an oxidant gas discharge hole 26 for discharging oxidant gas at one end in the long side direction X, and an oxidant gas supply hole 27 for supplying oxidant gas, a cooling medium supply hole 28 for supplying cooling medium, and a fuel gas discharge hole 29 for discharging fuel gas at the other end. The fuel gas supply hole 24, the cooling medium discharge hole 25, and the oxidant gas discharge hole 26 are arranged in this order from one side to the other in the short side direction Y of the fuel cell cell 12. The oxidizer gas supply port 27, the cooling medium supply port 28, and the fuel gas discharge port 29 are arranged in this order from one side to the other in the short-side direction Y of the fuel cell cell 12. The first separator 21 has a surface with integrated ridges and grooves on both sides that form a plurality of first flow channels 30 that supply oxidizer gas to one side of the power generation unit 17 between the oxidizer gas supply port 27 and the oxidizer gas discharge port 26, as meandering flow channels in which the direction of oxidizer gas flow reverses multiple times. The second separator 22 has a surface with integrated ridges and grooves on both sides that form a plurality of second flow channels 33 that supply fuel gas to the other side of the power generation unit 17 between the fuel gas supply port 24 and the fuel gas discharge port 29, as meandering flow channels in which the direction of fuel gas flow reverses multiple times. Between the first separator 21 of one of two fuel cell cells 12 adjacent in the thickness direction Z and the second separator 22 of the other, a cooling medium flow region 34 is formed through which the cooling medium flows from the cooling medium supply port 28 side to the cooling medium discharge port 25 side. The first inversion portion 35 and the second inversion portion 38 of each of the multiple first flow channels 30 and the multiple second flow channels 33 extend inclined with respect to the short side direction Y and overlap so as to intersect between the cooling medium supply hole 28 and the cooling medium discharge hole 25 which are opposite each other in the long side direction X when viewed from the thickness direction Z.

[0050] Generally, the irregularities forming the multiple first channels of the first separator and the multiple second channels of the second separator are inseparable, and therefore create flow resistance when the cooling medium flows through the cooling medium flow region. Since the first and second channels are meandering channels, the general portion extends in the first direction (long side direction X) and the reversed portion extends in the second direction (short side direction Y). In this case, the cooling medium attempts to flow through the cooling medium flow region from the cooling medium supply hole to the cooling medium discharge hole. However, when the multiple first channels and multiple second channels are parallel and the irregularities in their reversed portions overlap between the cooling medium supply hole and the cooling medium discharge hole in the cooling medium flow region, the cooling medium will not flow to the portion where the irregularities overlap. As a result, there is a problem in that the cooling effect of the cooling medium in the fuel cell cell becomes more variable.

[0051] In this regard, according to the above configuration, the first inversion portion 35 and the second inversion portion 38 of each of the multiple first flow channels 30 and the multiple second flow channels 33 extend inclined with respect to the short side direction Y, and overlap so as to intersect between the cooling medium supply hole 28 and the cooling medium discharge hole 25 that are opposite each other in the long side direction X when viewed from the thickness direction Z. Therefore, the irregularities in the first inversion portion 35 and the second inversion portion 38 of the multiple first flow channels 30 and the multiple second flow channels 33 do not overlap in a parallel state between the cooling medium supply hole 28 and the cooling medium discharge hole 25 in the cooling medium flow region 34. Therefore, the flow of cooling medium from the cooling medium supply hole 28 to the cooling medium discharge hole 25 in the cooling medium flow region 34 is not obstructed. In addition, the first inversion portion 35 and the second inversion portion 38 of each of the multiple first flow channels 30 and the multiple second flow channels 33 can guide a portion of the cooling medium supplied from the cooling medium supply hole 28 to both sides in the short side direction Y in the cooling medium flow region 34. Therefore, the cooling medium flows evenly through the cooling medium flow region 34, which reduces variations in the cooling effect of the cooling medium in the fuel cell cell 12.

[0052] (2) In the fuel cell cell stack 13, the first inversion portion 35 and the second inversion portion 38 of each of the multiple first flow channels 30 and the multiple second flow channels 33 extend in a straight line. According to the above configuration, the first inversion portion 35 and the second inversion portion 38 of each of the multiple first flow channels 30 and the multiple second flow channels 33 allow a portion of the cooling medium supplied from the cooling medium supply hole 28 to be smoothly guided to both sides in the short-side direction Y of the cooling medium flow region 34.

[0053] (3) In the fuel cell cell stack 13, the first general portion 36 and the second general portion 39 of the first flow path 30 and the second flow path 33, respectively, are wavy first wavy portion 37 and 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 are out of phase with respect to each other when the first separator 21 and the second separator 22 are superimposed.

[0054] 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 cooling medium can be circulated not only in the long-side direction X but also in the short-side direction Y in the region 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 circulation region 34.

[0055] (4) In the fuel cell 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 made from the same part, thus reducing the number of parts compared to the case where the first separator 21 and the second separator 22 are different parts.

[0056] <Example of changes> The above embodiment can be implemented with the following modifications. Furthermore, the above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0057] As shown in Figure 5, the first inverted portion 35 and the second inverted portion 38 may extend so as to be inclined with respect to the short side direction Y, on the opposite side from the case in the above embodiment. As shown in Figure 6, the first inverted portion 35 and the second inverted portion 38 may extend in an L-shape, inclined with respect to the short side direction Y.

[0058] The first separator 21 and the second separator 22 do not necessarily have the same configuration. In other words, the first separator 21 and the second separator 22 may have different configurations.

[0059] The first general portion 36 and the second general portion 39 of the first channel 30 and the second channel 33 do not necessarily have to be a wavy first wavy portion 37 and the second wavy portion 40, respectively. That is, the first general portion 36 and the second general portion 39 may each extend in a straight line, for example.

[0060] The first inversion portion 35 and the second inversion portion 38 do not necessarily have to extend in a straight line. That is, the first inversion portion 35 and the second inversion portion 38 may extend in a wavy shape, for example.

[0061] The positions of the oxidizer gas discharge port 26 and the oxidizer gas supply port 27 may be swapped. That is, the third port may be the oxidizer gas supply port 27 and the fourth port may be the oxidizer gas discharge port 26.

[0062] The positions of the fuel gas supply port 24 and the fuel gas discharge port 29 may be swapped. That is, the first port may be the fuel gas discharge port 29 and the sixth port may be the fuel gas supply port 24.

[0063] The positions of the cooling medium supply hole 28 and the cooling medium discharge hole 25 may be swapped. That is, the second hole may be the cooling medium supply hole 28 and the fifth hole may be the cooling medium discharge hole 25.

[0064] <Note> The above embodiment includes the configuration described in the following appendix. [Note 1] A fuel cell cell stack formed by stacking a plurality of rectangular plate-shaped fuel cell cells, each having a power generation section, a first separator and a second separator sandwiching the power generation section, and mutually orthogonal first and second sides, wherein the fuel cell cell has a first hole, a second hole and a third hole formed at one end in the first direction, which is the direction in which the first side extends, and a fourth hole, a fifth hole and a sixth hole formed at the other end, and the first hole, the second hole and the third hole are formed in the second direction, which is the direction in which the second side extends, from one side to the other. The holes are arranged in order, and the fourth, fifth, and sixth holes are arranged in this order from one side to the other in the second direction, with one of the first and sixth holes being a fuel gas supply hole through which fuel gas is supplied and the other being a fuel gas discharge hole through which the fuel gas is discharged, with one of the third and fourth holes being an oxidant gas supply hole through which oxidant gas is supplied and the other being an oxidant gas discharge hole through which the oxidant gas is discharged, and with one of the second and fifth holes being a cooling medium supply hole through which a cooling medium is supplied. One side is a cooling medium discharge hole through which the cooling medium is discharged, and the first separator has a front and back surface with irregularities that form a plurality of first flow channels that supply the oxidizing gas to one side of the power generation unit between the oxidizing gas supply hole and the oxidizing gas discharge hole, as meandering flow channels in which the direction of flow of the oxidizing gas reverses multiple times, and the second separator has a front and back surface with irregularities that form a plurality of second flow channels that supply the fuel gas to the other side of the power generation unit between the fuel gas supply hole and the fuel gas discharge hole, as meandering flow channels in which the direction of flow of the fuel gas reverses multiple times. A fuel cell stack having a uniform surface, wherein a cooling medium flow region is formed between the first separator of one of two adjacent fuel cell cells in the stacking direction and the second separator of the other, through which the cooling medium flows from the cooling medium supply hole side toward the cooling medium discharge hole side, and the inverted portions of the plurality of first flow channels and the plurality of second flow channels extend inclined with respect to the second direction and overlap so as to intersect between the cooling medium supply hole and the cooling medium discharge hole that are opposite to each other in the first direction when viewed from the stacking direction.

[0065] [Note 2] The fuel cell cell stack according to [Note 1], characterized in that the inversion portions of each of the plurality of first channels and the plurality of second channels extend in a straight line. [Note 3] The general portion of both the first and second flow channels, excluding the inversion portion, is a wavy portion, and the wavy portion of the first flow channel and the wavy portion of the second flow channel are out of phase with respect to each other when the first separator and the second separator are superimposed, as described in [Note 1] or [Note 2].

[0066] [Note 4] The fuel cell cell stack described in any one of [Note 1] to [Note 3], characterized in that the first separator and the second separator have the same configuration. [Explanation of symbols]

[0067] 11...fuel cell 12… Fuel cell 13…Fuel cell stack 14… End plate 15... Volts 16... Nut 17…Power Generation Department 18…Support slot 19…Gas diffusion layer 20... Separator 21...First separator 22...Second separator 23…Opening 24…Fuel gas supply port as an example of a first hole 25...Cooling medium discharge hole as an example of a second hole 26…An example of a third hole: an oxidizing gas exhaust hole 27…An example of a fourth hole: an oxidizing gas supply hole 28...Cooling medium supply hole as an example of a fifth hole 29…Fuel gas exhaust port as an example of a sixth hole 30…First channel 31...Concave part 32...Convex part 33…Second channel 34…Cooling medium distribution area 35...First inverted section as an example of an inverted section 36...The first general part as an example of a general part 37...First wavy section as an example of a wavy section 38...The second inverted section as an example of an inverted section 39...The second general part as an example of the general part 40...The second wavy section as an example of a wavy section. X... Long side direction as an example of the first direction Y...Short side direction as an example of a second direction Z... thickness direction (layering direction)

Claims

1. A fuel cell cell stack formed by stacking multiple rectangular plate-shaped fuel cell cells, each having a power generation section, a first separator and a second separator sandwiching the power generation section, and mutually orthogonal first and second sides, The aforementioned fuel cell cell is A first hole, a second hole, and a third hole are formed at one end in the first direction in which the first side extends, and a fourth hole, a fifth hole, and a sixth hole are formed at the other end, and the first hole, the second hole, and the third hole are arranged in this order from one side to the other in the second direction in which the second side extends, and the fourth hole, the fifth hole, and the sixth hole are arranged in this order from one side to the other in the second direction, Of the first and sixth holes, one is a fuel gas supply hole into which fuel gas is supplied, and the other is a fuel gas discharge hole into which the fuel gas is discharged. Of the third and fourth holes, one is an oxidizing gas supply hole through which the oxidizing gas is supplied, and the other is an oxidizing gas discharge hole through which the oxidizing gas is discharged. Of the second hole and the fifth hole, one is a cooling medium supply hole through which the cooling medium is supplied, and the other is a cooling medium discharge hole through which the cooling medium is discharged. The first separator has a surface with integrated indentations on both sides, forming a plurality of first channels on one side of the power generation section, which supply the oxidizing gas from the oxidizing gas supply hole to the oxidizing gas discharge hole, as meandering channels in which the flow direction of the oxidizing gas reverses multiple times. The second separator has a surface with integrated irregularities on both sides, forming multiple second flow paths on the other side of the power generation section, between the fuel gas supply hole and the fuel gas discharge hole, which supply the fuel gas as a meandering flow path in which the direction of fuel gas flow reverses multiple times. Between the first separator of one of the two fuel cell cells adjacent in the stacking direction and the second separator of the other, a cooling medium flow region is formed through which the cooling medium flows from the cooling medium supply hole side toward the cooling medium discharge hole side. A fuel cell stack characterized in that the inverted portions of each of the plurality of first channels and the plurality of second channels extend inclined with respect to the second direction and overlap so as to intersect between the cooling medium supply hole and the cooling medium discharge hole that are opposite to each other in the first direction when viewed from the stacking direction.

2. The fuel cell cell stack according to claim 1, characterized in that the inverted portions of each of the plurality of first channels and the plurality of second channels extend in a straight line.

3. The general portion of both the first and second flow channels, excluding the inversion portion, is a wavy, corrugated section. The fuel cell cell stack according to claim 1 or 2, characterized in that the wavy portion of the first channel and the wavy portion of the second channel are out of phase with respect to each other when the first separator and the second separator are superimposed.

4. The fuel cell cell stack according to claim 1 or 2, characterized in that the first separator and the second separator have the same configuration.

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