Fuel cell stack gas distribution structure

Abstract

To provide a distribution structure of a fuel battery manifold capable of uniformly supplying a gas to a manifold hole.SOLUTION: A gas distribution structure of a fuel cell stack 11, comprises: a first housing 40 covering a part where an oxidant gas supply hole 33 opens in one end surface 39 of a cell lamination body 13. The first housing 40 includes: an inflow port 41 that flows an oxidant gas into an internal part while being opposite to the oxidant gas supply hole 33 in a thickness direction Z; a drainage port 42 that drains the oxidant gas of the internal part to the oxidant gas supply hole 33 so as to be adjacent to the oxidant gas supply hole 33; and a distribution chamber 43 that connects the inflow port 41 and the drainage port 42. The inflow port 41 is arranged at a position opposite to a center part of the drainage port 42 in the thickness direction Z. At the position opposite to the inflow port 41 in the drainage port 42 in the thickness direction Z, an obstacle 44 is arranged.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a gas distribution structure for a fuel cell stack. [Background technology]

[0002] A known conventional fuel cell stack is shown in Patent Document 1, for example. Such a fuel cell stack has a structure in which a plurality of unit cells (single cells) are stacked and sandwiched between a pair of end plates on both sides in the stacking direction. One of the end plates is provided with one fuel gas inlet and one fuel gas outlet, as well as a plurality of oxidant gas inlet and a plurality of oxidant gas outlet holes arranged side by side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-72755 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described fuel cell stack, for example, when supplying oxidant gas (gas) from one pipe to a plurality of oxidant gas supply holes (manifold holes), it is necessary to do the following: The pipe must be connected to the end plate so that the oxidant gas supply port in the pipe is widened in the direction in which the plurality of oxidant gas supply holes are arranged and the supply port covers all of the oxidant gas supply holes.

[0005] However, in this case, when oxidant gas is supplied from the supply port of the piping to multiple oxidant gas supply holes, there will be a difference in the amount of oxidant gas supplied between the oxidant gas supply holes closest to the supply port and the oxidant gas supply holes farthest from the supply port, which results in the problem that oxidant gas cannot be supplied uniformly to the multiple oxidant gas supply holes. [Means for solving the problem]

[0006] The means for solving the above problems and their effects will be described below. The gas distribution structure of a fuel cell stack that solves the above-mentioned problems is a gas distribution structure of a fuel cell stack that is provided on an end face in the stacking direction of a cell stack formed by stacking a plurality of single cells, and distributes gas to manifold holes that open and extend in one direction along the end face of the cell stack, and includes a housing that covers the portion of the end face of the cell stack where the manifold holes open, the housing having an inlet that faces the manifold holes in the stacking direction and allows the gas to flow into the interior, an outlet that extends along the manifold holes and is adjacent to the manifold holes and allows the gas inside to flow out to the manifold holes, and a distribution chamber that connects the inlet and the outlet, the inlet is located at a position opposite, in the stacking direction, to a center portion of the outlet in the direction in which the outlet extends, and an obstacle is located in the distribution chamber or the outlet at a position opposite, in the stacking direction, to the inlet.

[0007] Typically, in a distribution chamber, the gas flow rate decreases the farther away from the inlet in the direction in which the outlet extends. Therefore, the amount of gas flowing from the outlet to the manifold hole becomes non-uniform throughout the entire outlet. In this regard, with the above configuration, gas flowing into the distribution chamber from the inlet hits an obstacle. As a result, in the distribution chamber, the gas is dispersed to positions farther away from the inlet in the direction in which the outlet extends. This results in a uniform flow rate of gas in the distribution chamber. Therefore, the amount of gas flowing from the outlet to the manifold hole becomes uniform, allowing gas to be supplied uniformly to the manifold hole. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view of a fuel cell stack according to an embodiment. [Figure 2]FIG. 2 is an exploded perspective view showing a unit cell of the fuel cell stack. [Figure 3] FIG. 2 is an exploded perspective view showing a power generation unit of a single cell. [Figure 4] Schematic plan view of the single cell in Figure 2. [Figure 5] Cross-sectional view taken along line 5-5 in Figure 4. [Figure 6] FIG. [Figure 7] FIG. 2 is an enlarged cross-sectional view of a main part of FIG. 1. [Figure 8] FIG. 10 is an enlarged cross-sectional view of a main part of a fuel cell stack according to a modified example. [Figure 9] FIG. 10 is a bottom view of the first housing provided with an obstacle according to a modified example. [Figure 10] FIG. 10 is a bottom view of the first housing provided with an obstacle according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of a fuel cell stack will now be described with reference to the drawings. <Fuel cell stack 11> 1, the fuel cell stack 11 includes a rectangular parallelepiped cell stack 13 formed by stacking a plurality of rectangular plate-shaped unit cells 12. The cell stack 13 is sandwiched between a pair of end plates (not shown) on both sides in the stacking direction, which coincides with the thickness direction Z of the unit cells 12.

[0010] <Single cell 12> 2, the single cell 12 includes a rectangular plate-shaped power generation unit 14, a pair of rectangular sheet-shaped gas diffusion layers 15 sandwiching the power generation unit 14, and a pair of rectangular plate-shaped separators 16. That is, the single cell 12 has a structure in which the pair of gas diffusion layers 15, the power generation unit 14, and the pair of separators 16 are stacked.

[0011] In the following description, the long side direction, short side direction, and thickness direction of the unit cell 12 are respectively referred to as long side direction X, short side direction Y, and thickness direction Z. The long side direction X, short side direction Y, and thickness direction Z are directions that are perpendicular to each other.

[0012] 2, one of the pair of gas diffusion layers 15 (cathode side) is a first gas diffusion layer 17, and the other (anode side) is a second gas diffusion layer 18. One of the pair of separators 16 (cathode side) is a first separator 19, and the other (anode side) is a second separator 20.

[0013] <Generation Unit 14> 2 and 3, the power generation unit 14 includes a rectangular plate-shaped resin frame member 21 and a rectangular sheet-shaped membrane electrode assembly (MEA) 22 supported by the frame member 21. The frame member 21 has a rectangular opening 23 in the center. A rectangular annular support portion 24 is formed around the periphery of the opening 23 in the frame member 21 and is thinner than other portions to support the periphery of the membrane electrode assembly 22.

[0014] The peripheral edge of the membrane electrode assembly 22 is supported on the surface of the support 24 facing the first gas diffusion layer 17, so that the entire opening 23 is covered by the membrane electrode assembly 22. In this case, the peripheral edge of the membrane electrode assembly 22 is bonded to the surface of the support 24 facing the first gas diffusion layer 17 with, for example, an adhesive.

[0015] 2 to 5, the pair of gas diffusion layers 15 are arranged so that the long side direction X and the short side direction Y coincide with the opening 23 of the frame member 21. The first gas diffusion layer 17 has lengths in the long side direction X and the short side direction Y that are slightly longer than the opening 23. The second gas diffusion layer 18 has lengths in the long side direction X and the short side direction Y that are the same as the opening 23. The pair of separators 16 sandwich the power generation unit 14 in the thickness direction Z from the outside of the pair of gas diffusion layers 15.

[0016] An oxidant gas containing oxygen is supplied to one side (cathode side) of the membrane electrode assembly 22 in the thickness direction Z of the unit cell 12, and a fuel gas containing hydrogen is supplied to the other side (anode side) of the membrane electrode assembly 22 in the thickness direction Z. As a result, the unit cell 12 generates electricity based on an electrochemical reaction between the oxidant gas and the fuel gas in the membrane electrode assembly 22.

[0017] <Flow path configuration using unit cell 12> 1 to 5 , two rectangular first through holes aligned in the short side direction Y are formed at each end of the unit cell 12, sandwiching the membrane electrode assembly 22 in the long side direction X. That is, two rectangular first through holes aligned in the short side direction Y are formed at each end of the frame member 21 and the pair of separators 16, sandwiching the membrane electrode assembly 22 in the long side direction X. The two first through holes at one end of the unit cell 12 in the long side direction X serve as a fuel gas inlet 25 and a coolant outlet 26.

[0018] The two first through holes at the other end of the unit cell 12 in the long side direction X serve as a coolant supply hole 27 and a fuel gas discharge hole 28. The fuel gas supply hole 25 constitutes an inlet-side fuel gas manifold 29 to which fuel gas is supplied in the fuel cell stack 11. The fuel gas discharge hole 28 constitutes an outlet-side fuel gas manifold 30 from which fuel gas is discharged in the fuel cell stack 11.

[0019] The coolant supply holes 27 form an inlet-side coolant manifold 31 through which the coolant is supplied in the fuel cell stack 11. The coolant discharge holes 26 form an outlet-side coolant manifold 32 through which the coolant is discharged in the fuel cell stack 11.

[0020] Three rectangular second through holes are formed at each of both ends of the unit cell 12 sandwiching the membrane electrode assembly 22 in the short side direction Y, i.e., both ends of the frame member 21 and the pair of separators 16 sandwiching the membrane electrode assembly 22 in the short side direction Y, and are arranged at equal intervals in the long side direction X. The three second through holes at one end of the unit cell 12 in the short side direction Y are oxidant gas supply holes 33 as an example of manifold holes. The three second through holes at the other end of the unit cell 12 in the short side direction Y are oxidant gas discharge holes 34.

[0021] The oxidant gas supply holes 33 constitute an inlet-side oxidant gas manifold 35 to which the oxidant gas is supplied in the fuel cell stack 11. The oxidant gas discharge holes 34 constitute an outlet-side oxidant gas manifold 36 from which the oxidant gas is discharged in the fuel cell stack 11. Each of the manifolds extends in the stacking direction (thickness direction Z) of the unit cells 12 in the state where the cell stack 13 is configured.

[0022] An oxidant gas flow path 37 is formed between the frame member 21 and the membrane electrode assembly 22 on the one hand and the first separator 19 on the other hand, and causes the oxidant gas supplied from the oxidant gas supply hole 33 to pass through the membrane electrode assembly 22 in the short side direction Y and flow to the oxidant gas discharge hole 34 on the other hand. The oxidant gas flow path 37 is made up of a plurality of grooves formed on the surface of the first separator 19 facing the membrane electrode assembly 22 on the other hand.

[0023] A fuel gas flow path 38 is formed between the frame member 21 and the membrane electrode assembly 22 on the one hand and the second separator 20 on the other hand, and causes the fuel gas supplied from the fuel gas supply hole 25 to pass through the membrane electrode assembly 22 in the long side direction X and flow to the fuel gas discharge hole 28 on the other hand. The fuel gas flow path 38 is constituted by a plurality of grooves formed on the surface of the second separator 20 facing the membrane electrode assembly 22 on the other hand.

[0024] When a plurality of unit cells 12 are stacked to form the fuel cell stack 11, a coolant flow path (not shown) is formed between the first separator 19 of one of two unit cells 12 adjacent to each other in the stacking direction (thickness direction Z) and the second separator 20 of the other unit cell 12. The coolant flow path (not shown) allows the coolant (e.g., cooling water) supplied from the coolant supply holes 27 to flow to the coolant discharge holes 26.

[0025] <Gas distribution structure of fuel cell stack 11> 1 and 7, three rectangular oxidant gas supply holes 33 are opened at one end in the short side direction Y of one end face 39 of the cell stack 13 of the fuel cell stack 11 in the stacking direction (thickness direction Z) of the unit cells 12. The three oxidant gas supply holes 33 open and extend in one direction, that is, the long side direction X, along the one end face 39. The three oxidant gas supply holes 33 are arranged side by side at equal intervals in the long side direction X.

[0026] The three oxidant gas supply holes 33 respectively constitute three inlet-side oxidant gas manifolds 35. That is, three inlet-side oxidant gas manifolds 35 extending in the stacking direction (thickness direction Z) of the unit cells 12 are formed at one end of the cell stack 13 in the short-side direction Y. The three inlet-side oxidant gas manifolds 35 extend parallel to one another and are arranged at equal intervals in the long-side direction X.

[0027] A first housing 40 as an example of a housing is provided on one end surface 39 of the cell stack 13. The first housing 40 covers the portion of the end surface 39 where the three oxidant gas supply holes 33 open. The first housing 40 distributes oxidant gas as an example of a gas to the three oxidant gas supply holes 33.

[0028] 1, 6, and 7, the first housing 40 includes an inlet 41, an outlet 42, and a distribution chamber 43. The inlet 41 allows the oxidant gas to flow into the distribution chamber 43 that forms the internal space of the first housing 40. The inlet 41 is disposed at the end opposite the oxidant gas supply hole 33 side in the thickness direction Z.

[0029] The inlet 41 has a rectangular shape and faces, in the thickness direction Z, the central oxidant gas supply hole 33 among the three oxidant gas supply holes 33 aligned in the long side direction X. The inlet 41 is located in the center of the first housing 40 in the long side direction X.

[0030] The outlet 42 is disposed at the end on the oxidant gas supply hole 33 side in the thickness direction Z. That is, the outlet 42 is disposed adjacent to each oxidant gas supply hole 33. The outlet 42 has a rectangular shape extending in the long side direction X along each oxidant gas supply hole 33.

[0031] The outlet 42 is open over almost the entire surface of the first housing 40 facing the oxidant gas supply holes 33. The width of the outlet 42 in the long side direction X is several times the width of the inlet 41 in the long side direction X. The width of the outlet 42 in the short side direction Y is approximately the same as the width of the inlet 41 in the short side direction Y. The outlet 42 allows the oxidant gas in the distribution chamber 43 that constitutes the internal space of the first housing 40 to flow out into each of the three oxidant gas supply holes 33 (the three inlet-side oxidant gas manifolds 35).

[0032] The oxidant gas that flows into the distribution chamber 43 from the inlet 41 flows out from the outlet 42 to the three oxidant gas supply holes 33. In other words, the distribution chamber 43 connects the inlet 41 and the outlet 42. The inlet 41 is disposed at a position opposite, in the thickness direction Z, to the center of the outlet 42 in the long side direction X, which is the direction in which the outlet 42 extends. An obstacle 44 is disposed at a position at the outlet 42 opposite the inlet 41 in the thickness direction Z, i.e., at the center of the outlet 42 in the long side direction X.

[0033] The obstacle 44 has a rectangular plate shape and is formed integrally with the first housing 40. The obstacle 44 faces the inlet 41 in the thickness direction Z. The width of the obstacle 44 in the long side direction X is narrower than the width of the inlet 41 in the long side direction X. The obstacle 44 covers the center in the long side direction X of the central oxidant gas supply hole 33 of the three oxidant gas supply holes 33 lined up in the long side direction X.

[0034] The first housing 40 has a shape that is perpendicular to an axis extending in the long side direction X and is plane-symmetrical with respect to a plane that bisects the inlet 41 and the outlet 42. Both side surfaces of the first housing 40 in the short side direction Y are perpendicular to the axis extending in the short side direction Y. Both side surfaces of the first housing 40 in the long side direction X are perpendicular to the axis extending in the long side direction X.

[0035] In the first housing 40, the surface connecting both side surfaces in the long side direction X and both sides in the long side direction X of the inlet 41 is inclined with respect to one end surface 39 of the cell stack 13 so that the closer it is to the inlet 41 in the long side direction X, the farther it is from the outlet 42 in the thickness direction Z.

[0036] 1, three rectangular oxidant gas discharge holes 34 are opened at the other end in the short side direction Y of one end face 39 of the cell stack 13 of the fuel cell stack 11 in the stacking direction (thickness direction Z) of the unit cells 12. The three oxidant gas discharge holes 34 open and extend in one direction, that is, the long side direction X, along the one end face 39. The three oxidant gas discharge holes 34 are arranged side by side at equal intervals in the long side direction X.

[0037] The three oxidant gas discharge holes 34 respectively constitute three outlet-side oxidant gas manifolds 36. That is, three outlet-side oxidant gas manifolds 36 extending in the stacking direction (thickness direction Z) of the unit cells 12 are formed at the other end of the cell stack 13 in the short-side direction Y. The three outlet-side oxidant gas manifolds 36 extend parallel to one another and are arranged at equal intervals in the long-side direction X.

[0038] A second housing 45 is provided on one end surface 39 of the cell stack 13, covering the portion of the one end surface 39 where the three oxidant gas discharge holes 34 open. The second housing 45 is the first housing 40 without the obstacle 44. In other words, the second housing 45 has the same configuration as the first housing 40, except that the obstacle 44 is not provided.

[0039] An opening in the second housing 45 corresponding to the outlet 42 of the first housing 40 serves as an inflow opening 46 through which the oxidant gas discharged from the three oxidant gas discharge holes 34 flows into the second housing 45. An opening in the second housing 45 corresponding to the inflow opening 41 of the first housing 40 serves as an outflow opening 47 through which the oxidant gas in the second housing 45 flows out. The first housing 40 and the second housing 45 may be formed integrally with, for example, an end plate (not shown).

[0040] A pipe (not shown) for supplying an oxidant gas is connected to the inlet 41 of the first housing 40. A pipe (not shown) for discharging the oxidant gas is connected to the outlet opening 47 of the second housing 45. A pipe (not shown) for supplying a fuel gas is connected to the inlet fuel gas manifold 29 that opens at one end surface 39 of the cell stack 13.

[0041] A pipe (not shown) for discharging fuel gas is connected to an outlet fuel gas manifold 30 that opens on one end surface 39 of the cell stack 13. A pipe (not shown) for supplying a cooling medium is connected to an inlet cooling medium manifold 31 that opens on one end surface 39 of the cell stack 13. A pipe (not shown) for discharging the cooling medium is connected to an outlet cooling medium manifold 32 that opens on one end surface 39 of the cell stack 13.

[0042] <Function of fuel cell stack 11> 1 and 7, when generating electricity using the fuel cell stack 11, an oxidant gas is supplied to the inlet 41 of the first housing 40, a fuel gas is supplied to the inlet-side fuel gas manifold 29, and a coolant is supplied to the inlet-side coolant manifold 31. At this time, the oxidant gas flowing in from the inlet 41 of the first housing 40 flows through the distribution chamber 43 and mainly toward the center of the outlet 42.

[0043] The oxidant gas flowing toward the center of the outlet 42 collides with an obstacle 44 arranged in the center of the outlet 42, or passes through the outlet 42 and flows into the central inlet-side oxidant gas manifold 35 of the three inlet-side oxidant gas manifolds 35. The oxidant gas that collides with the obstacle 44 is dispersed and flows through the distribution chamber 43 toward the inlet-side oxidant gas manifolds 35 located on either side of the central inlet-side oxidant gas manifold 35.

[0044] Therefore, in the distribution chamber 43, the oxidant gas flows dispersedly even to positions away from the inlet 41 in the long side direction X, which is the direction in which the outlet 42 extends. This uniformizes the flow rate of the oxidant gas in the distribution chamber 43, and therefore the amount of oxidant gas flowing out from the outlet 42 to the three inlet-side oxidant gas manifolds 35. Therefore, the oxidant gas is uniformly distributed and supplied to the three inlet-side oxidant gas manifolds 35.

[0045] Incidentally, if the first housing 40 is not provided with the obstacle 44, the following problem occurs: The oxidant gas flowing in from the inlet 41 of the first housing 40 flows through the distribution chamber 43 and flows from the outlet 42 mainly into the central inlet-side oxidant gas manifold 35 of the three inlet-side oxidant gas manifolds 35. In other words, the oxidant gas flowing in the distribution chamber 43 is hardly dispersed, and the flow rate of the oxidant gas in the distribution chamber 43 is not uniform.

[0046] For this reason, in the distribution chamber 43, it is difficult for the oxidant gas to flow toward the inlet-side oxidant gas manifolds 35 located on both sides of the central inlet-side oxidant gas manifold 35. Therefore, the oxidant gas in the distribution chamber 43 flows unevenly toward the central inlet-side oxidant gas manifold 35, and is therefore difficult to flow toward the inlet-side oxidant gas manifolds 35 located on both sides of the central inlet-side oxidant gas manifold 35. As a result, there is a problem in that the amounts of oxidant gas flowing into the three inlet-side oxidant gas manifolds 35 become uneven.

[0047] As described above, when the oxidant gas, fuel gas, and coolant are supplied to the fuel cell stack 11, power is generated in each of the unit cells 12 that make up the cell stack 13. 1, 4, and 5, when power is generated by the unit cell 12, oxidant gas is supplied from each oxidant gas inlet 33, and fuel gas is supplied from the fuel gas inlet 25. When oxidant gas is supplied from each oxidant gas inlet 33 in the unit cell 12, the oxidant gas passes through the oxidant gas flow channel 37 and flows to the oxidant gas outlet hole 34, and is diffused by the first gas diffusion layer 17 while being supplied to the cathode side surface of the membrane electrode assembly 22. The oxidant gas that has flowed to each oxidant gas outlet hole 34 flows through the outlet-side oxidant gas manifold 36 and the second housing 45, and is discharged from the outlet opening 47.

[0048] On the other hand, when fuel gas is supplied to the unit cell 12 through the fuel gas inlet 25, the fuel gas flows through the fuel gas flow channel 38 to the fuel gas outlet 28, and is diffused by the second gas diffusion layer 18 before being supplied to the anode-side surface of the membrane electrode assembly 22. The fuel gas that has flowed to the fuel gas outlet 28 flows through the outlet-side fuel gas manifold 30 and is discharged. At this time, in the unit cell 12, power is generated based on an electrochemical reaction in the membrane electrode assembly 22 between the oxidant gas supplied to the cathode-side surface of the membrane electrode assembly 22 and the fuel gas supplied to the anode-side surface of the membrane electrode assembly 22.

[0049] Each unit cell 12 generates heat due to the electric power generated by this electrochemical reaction. However, each unit cell 12 is cooled by the coolant flowing through a coolant flow path (not shown) between the first separator 19 of one of two adjacent unit cells 12 and the second separator 20 of the other unit cell 12 from the coolant supply hole 27 to the coolant discharge hole 26. The coolant that has flowed to the coolant discharge hole 26 flows through the outlet-side coolant manifold 32 and is discharged.

[0050] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) The gas distribution structure of the fuel cell stack 11 includes a first housing 40. The first housing 40 has an inlet 41, an outlet 42, and a distribution chamber 43 connecting the inlet 41 and the outlet 42. The inlet 41 is disposed at a position opposite to the center of the outlet 42 in the long side direction X, which is the direction in which the outlet 42 extends, in the thickness direction Z, which is the stacking direction. An obstacle 44 is disposed at a position on the outlet 42 opposite to the inlet 41 in the thickness direction Z.

[0051] Normally, in the distribution chamber 43, the flow rate of the oxidant gas decreases as the position moves away from the inlet 41 in the long side direction X along which the outlet 42 extends. Therefore, the amount of oxidant gas flowing from the outlet 42 to the three inlet-side oxidant gas manifolds 35 becomes uneven. In this regard, with the above configuration, the oxidant gas flowing into the distribution chamber 43 from the inlet 41 hits the obstacle 44. As a result, in the distribution chamber 43, the oxidant gas is dispersed even to positions far from the inlet 41 in the long side direction X along which the outlet 42 extends. This uniforms the flow rate of the oxidant gas in the distribution chamber 43. Therefore, the amount of oxidant gas flowing from the outlet 42 to the three inlet-side oxidant gas manifolds 35 becomes uniform, and the oxidant gas can be uniformly distributed and supplied to the three inlet-side oxidant gas manifolds 35.

[0052] Furthermore, in order to equalize the flow rate of the oxidant gas in the distribution chamber 43 without providing the obstacle 44 in the first housing 40, the first housing 40 needs to be made longer in the thickness direction Z, which poses a problem of increasing the size of the fuel cell stack 11. In this regard, in the present embodiment, by providing the obstacle 44 in the first housing 40, the length of the first housing 40 in the thickness direction Z can be further shortened, which contributes to the miniaturization of the fuel cell stack 11.

[0053] (2) In the gas distribution structure of the fuel cell stack 11, the obstacle 44 is formed integrally with the first housing 40. According to the above configuration, the number of parts can be reduced compared to when the obstacle 44 is configured as a separate member from the first housing 40. Furthermore, when the obstacle 44 and the first housing 40 are configured from resin, the obstacle 44 and the first housing 40 can be easily manufactured by integral molding.

[0054] (Example of change) The above embodiment can be modified as follows: Furthermore, the above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0055] 8, a plurality of obstacles 44 may be arranged at the outlet 42 of the first housing 40, with the size of the obstacles 44 decreasing with increasing distance from the center of the outlet 42 in the long side direction X, which is the direction in which the outlet 42 extends. In this case, the plurality of obstacles 44 (three in this example) are preferably arranged symmetrically with respect to the obstacle 44 arranged at the center of the outlet 42. In this case, the cell stack 13 is provided with one inlet-side oxidant gas manifold 35 whose width in the long side direction X is the same as the width of the outlet 42.

[0056] Normally, in the distribution chamber 43, the flow rate of the oxidant gas decreases with increasing distance from the inlet 41 in the long side direction X along which the outlet 42 extends. Therefore, the amount of oxidant gas flowing from the outlet 42 to one inlet-side oxidant gas manifold 35 becomes non-uniform throughout the outlet 42. In this regard, with the above-described configuration, the oxidant gas flowing into the distribution chamber 43 from the inlet 41 collides with the obstacle 44 disposed in the center of the outlet 42. As a result, in the distribution chamber 43, the oxidant gas is dispersed to positions farther from the inlet 41 in the long side direction X along which the outlet 42 extends. At this time, the flow rate of the dispersed oxidant gas decreases with increasing distance from the center of the outlet 42 in the long side direction X along which the outlet 42 extends. However, with the above-described configuration, the size of the multiple (three in this example) obstacles 44 disposed at the outlet 42 decreases with increasing distance from the center of the outlet 42 in the long side direction X along which the outlet 42 extends. This reduces the difference in the flow rate of the oxidant gas depending on the distance from the center of the outlet 42 in the long side direction X along which the outlet 42 extends. Therefore, the amount of oxidant gas flowing from the outlet 42 to one inlet-side oxidant gas manifold 35 becomes more uniform throughout the outlet 42. As a result, the oxidant gas can be more uniformly dispersed and supplied throughout one inlet-side oxidant gas manifold 35.

[0057] As shown in FIG. 9, when the obstacle 44 is viewed from the thickness direction Z, both sides of the obstacle 44 in the long side direction X may be changed to have an arc shape that bulges inward. As shown in FIG. 10 , the obstacle 44 may be modified to have a shape such that, when viewed from the thickness direction Z, the opening area of ​​the outlet 42 increases with increasing distance from the center in the long side direction X in which the outlet 42 extends.

[0058] The obstacle 44 may be modified to have any shape when viewed from the thickness direction Z, such as an ellipse, a perfect circle, a polygon other than a rectangle, a star, or a cross. The number of oxidant gas supply holes 33, which are an example of manifold holes, opening on one end surface 39 of the cell stack 13 may be changed as appropriate.

[0059] The shape of the outlet 42 is not limited to a rectangular shape, and may be changed to any shape, such as a circular shape, an elliptical shape, or a polygonal shape other than a rectangular shape, as long as it can cover all of the oxidant gas supply holes 33 (manifold holes) opening on one end surface 39 of the cell stack 13.

[0060] The obstacle 44 may be disposed at a position facing the inlet 41 of the distribution chamber 43 in the stacking direction (thickness direction Z). The obstacle 44 may have not only a planar shape such as a plate, but also a three-dimensional shape such as a rectangular parallelepiped.

[0061] The obstacle 44 may have a partial cutout or through-hole formed therein. The gas distribution structure of the fuel cell stack 11 is not limited to the oxidant gas supply holes 33, but may also be applied to the fuel gas supply holes 25 as an example of manifold holes. [Explanation of symbols]

[0062] 11...Fuel cell stack 12...Single cell 13...Cell stack 14...Power generation unit 15...Gas diffusion layer 16...Separator 17...First gas diffusion layer 18...Second gas diffusion layer 19...First separator 20...Second separator 21...Frame member 22...Membrane electrode assembly 23...Opening 24...Support part 25...Fuel gas supply hole (manifold hole) 26…Cooling medium discharge hole 27…Cooling medium supply hole 28...Fuel gas exhaust hole 29...Inlet fuel gas manifold 30...Outlet fuel gas manifold 31...Inlet cooling medium manifold 32...Outlet cooling medium manifold 33...Oxidant gas supply hole (manifold hole) 34...Oxidant gas exhaust hole 35...Inlet oxidant gas manifold 36...Outlet side oxidizer gas manifold 37...oxidant gas flow path 38...Fuel gas flow path 39...One end surface (end surface) 40...First housing (housing) 41...Inlet 42... Outlet 43...Distribution room 44...Obstacle 45...Second housing 46…Inflow opening 47...Outlet opening X: Long side direction Y: Short side direction Z...thickness direction (layer direction)

Claims

1. A gas distribution structure for a fuel cell stack, the gas distribution structure being provided on an end surface in a stacking direction of a cell stack formed by stacking a plurality of unit cells, and distributing gas to manifold holes that open and extend in one direction along the end surface of the cell stack, a housing that covers a portion of the end surface of the cell stack where the manifold hole opens, the housing has an inlet facing the manifold hole in the stacking direction and allowing the gas to flow into an interior thereof, an outlet extending along the manifold hole and adjacent to the manifold hole and allowing the gas inside to flow out to the manifold hole, and a distribution chamber connecting the inlet and the outlet, the inlet is disposed at a position opposite, in the stacking direction, to a center portion of the outlet in a direction in which the outlet extends, 10. A gas distribution structure for a fuel cell stack, wherein an obstacle is disposed in the distribution chamber or the outlet at a position facing the inlet in the stacking direction.

2. a plurality of the obstacles are arranged at the outlet, 2. The gas distribution structure of a fuel cell stack according to claim 1, wherein the plurality of obstacles decrease in size as they move away from the center of the outlet in the direction in which the outlet extends.

3. 3. The gas distribution structure for a fuel cell stack according to claim 1, wherein the obstacle is formed integrally with the housing.

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