Fuel cell manifold structure

Abstract

To enable an improve of a power generation efficiency with a simple configuration.SOLUTION: A unit cell 4 has a fluid passage 20 provided between a membrane electrode assembly 5 and a separator 6, and a connection passage 13 connecting a communication hole 7 and a fluid passage 20. A fluid manifold 10 is extended in a stacking direction of the unit cell 4 of a stacked cell stack 2 so as to communicate with the communication hole 7 formed in the respective unit cell 4, and supplies a fluid H to the respective unit cell 4. The fluid manifold 10 has an inlet part 11 provided with an inlet 11a through which the fluid H flows at one end 10a communicating with an outside of a stack case 3, and a closing part 12 at the other end 10b located on an opposite side of the inlet part 11. The inlet part 11 is provided with a biasing part 9 that biases the fluid H flowing into the fluid manifold 10 toward the connection path 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A conventional manifold structure for a fuel cell includes an internal manifold formed inside a fuel cell stack, which is made up of multiple stacked fuel cells, and communicating with the stack in the stacking direction. The manifold structure also includes an external fluid passage that supplies fluid to the internal manifold, and a connector that connects the external fluid passage to the internal manifold. Each fuel cell also includes an internal fluid passage that is connected perpendicularly to the internal manifold. Some conventional fuel cells are further configured to generate a swirling flow within the internal manifold that swirls along the inner wall of the manifold using the energy of the fluid flowing from the external fluid passage into the internal manifold, in order to uniform the amount of fluid supplied to each internal fluid passage (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4872918 Summary of the Invention [Problem to be solved by the invention]

[0004] The manifold structure of the fuel cell in Patent Document 1 generates a swirling flow to prevent uneven distribution of fluid. However, in this structure, the flow velocity is high in the portion of the stacking direction of the unit cells corresponding to the inlet unit cell, and the fluid passes through without any movement. Furthermore, it is necessary to improve power generation efficiency by uniformly distributing static pressure within the fluid manifold. For example, to achieve this, the size or connection shape of the external manifold that constitutes the external fluid passage may be changed to generate a swirling flow. However, increasing the size of the external manifold or changing the connection shape increases the protruding dimension, which reduces space efficiency.

[0005] In addition, there is a known technology in which a separate component such as a spacer with a large flow resistance is provided inside the internal manifold (also referred to as a fluid manifold). In such a system, it is necessary to change the shape of the fuel cell stack (also referred to as a stacked cell stack) that forms the fluid manifold, which poses a problem in that unit cells of the same shape cannot be used. Furthermore, near the end plate blocking the opposite side of the inlet, the flow rate is the same at positions close to and far from the active region. Here, the active region refers to the region formed by the membrane electrode assembly located at the center of the membrane electrode structure among the unit cells stacked in the stacked cell stack. Therefore, the fluid that bounces off the end plate and heads toward the inlet side interferes with the fluid heading toward the end plate, hindering smooth flow.

[0006] In this way, the static pressure distribution within the fluid manifold is disturbed at each location in the direction in which the unit cells are stacked, making it difficult to uniformize the amount of fluid supplied to each unit cell, and further improvement is required. An object of the present invention is to provide a manifold structure for a fuel cell that can improve power generation efficiency with a simple configuration. [Means for solving the problem]

[0007] To solve the above problems, the manifold structure for a fuel cell of the present invention includes a stacked cell stack in which a plurality of unit cells, each having a membrane electrode assembly and a separator, are stacked to form an active region. The manifold structure for a fuel cell also includes a stack case that houses the stacked cell stack. The manifold structure further includes a fluid manifold that extends in the stacking direction of the unit cells of the stacked cell stack, connecting the communication holes formed in each unit cell to supply fluid to each unit cell. Each unit cell has a fluid passage between the membrane electrode assembly and the separator, and a connecting path that connects the communication hole to the fluid passage. The fluid manifold has an inlet portion at one end that communicates with the outside of the stack case, where the inlet portion has an inlet for allowing fluid to flow in, and a closing portion located at the other end opposite the inlet portion. The inlet portion is characterized by having a bias portion that biases fluid flowing into the fluid manifold toward the connecting path. [Effects of the Invention]

[0008] According to the present invention, a manifold structure for a fuel cell is provided that can improve power generation efficiency with a simple configuration. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view of a fuel cell illustrating the overall configuration of a manifold structure of a fuel cell according to a first embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view illustrating the configuration of an inlet portion in the manifold structure of the fuel cell according to the first embodiment. [Figure 3] FIG. 3 is a vertical cross-sectional view illustrating the flow of fluid inside the fluid manifold of the first embodiment. [Figure 4] 4 is a view taken in the direction of arrow IV in FIG. 3, showing the shape of an inlet portion inside the fluid manifold of the first embodiment. [Figure 5] FIG. 10 is a longitudinal cross-sectional view illustrating the flow of fluid inside a fluid manifold shown as a comparative example. [Figure 6] 1 is a schematic side view showing the overall configuration of a fuel cell, with arrows illustrating the flow of fluids. [Figure 7]1 is a graph showing the change in static pressure from the inlet side to the occlusion side in a fluid manifold of a fuel cell. [Figure 8] FIG. 10 is a vertical cross-sectional view illustrating the configuration of an inlet portion of a fluid manifold according to a second embodiment. [Figure 9] FIG. 10 is a vertical cross-sectional view illustrating the configuration of an inlet portion of a fluid manifold according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes an embodiment of a manifold structure for a fuel cell according to the present invention, with reference to the accompanying drawings. Identical components are designated by the same reference numerals, and redundant description will be omitted. The manifold structure of a fuel cell of the first embodiment shown in Figure 1 includes a stacked cell stack 2 in which a plurality of unit cells 4, each having a membrane electrode assembly 5 and a separator 6, are stacked in a stacking direction W to provide an active region 8. The manifold structure also includes a stack case 3 that houses the stacked cell stack 2. In this embodiment, the active region 8 is a region formed by a membrane electrode assembly 5a located at the center of the membrane electrode assembly 5 of the unit cells 4 stacked in the stacked cell stack 2. In the manifold structure of this embodiment, this region does not include a portion where dummy cells 14, which will be described later, are stacked.

[0011] The stack case 3 has a box-shaped housing 3a, an inlet-side end frame 3b that constitutes a part of the inlet-side end unit, and a blocking-side end frame 3c that constitutes a part of the blocking-side end unit. The inlet-side end unit of the first embodiment further has a piping-side insulator 15 and a cell-side inlet insulator 16 that form the inlet section 11 described below. The closed-section-side end unit of the first embodiment further has a cell-side insulator 17 and an end-frame-side insulator 18 that form the closed section 12.

[0012] Each unit cell 4 has a membrane electrode assembly 5 and separators 6 arranged on both sides of the membrane electrode assembly 5. The unit cell 4 also has a fluid passage 20 between the membrane electrode assembly 5 and the separator 6. The unit cell 4 also has a connecting path 13 that connects the communication hole 7 and the fluid passage 20. The membrane electrode assembly 5 generates electricity by supplying different types of gases, such as hydrogen and oxygen, to both sides of the assembly 5. A cooling fluid (refrigerant) is supplied between the unit cells 4 (between the separators 6). The membrane electrode structure 5 has membrane electrode assemblies 5a whose outer periphery is surrounded by a frame member 5b, and the area around these membrane electrode assemblies forms an active region 8. When generating electricity, a fluid H is supplied to fluid passages 20 formed between the membrane electrode assembly and each of the separators 6 provided on both sides. As a result, each unit cell 4 generates electricity by causing a hydrogen oxidation reaction (HOR) at the negative electrode side (anode) of the membrane electrode assembly and an oxygen reduction reaction (ORR) at the positive electrode side (cathode).

[0013] The voltage generated by each unit cell 4 becomes the output voltage of the fuel cell 1 between a pair of positive and negative electrodes 19 a, 19 b arranged on both the left and right sides of the active region 8 . Therefore, in order to stabilize the output voltage of the fuel cell 1 and obtain good power generation efficiency, it is desirable to equalize the flow rate distribution of the fluid H supplied to the membrane electrode assembly portion so that each unit cell 4 generates power evenly.

[0014] The manifold structure of the fuel cell 1 includes a fluid manifold 10 that connects the communication holes 7 formed as openings in the unit cells 4 stacked in the stacking direction W. The fluid manifold 10 has a distribution path 10c extending in the stacking direction W of the unit cells 4 of the stacked cell stack, an inlet side distribution path 10d connected to the inlet section 11 side of the distribution path 10c in the stacking direction W, and a blocked side area 10e connected to the blocked section 12 side of the distribution path 10c, all of which are connected to each other.

[0015] Specifically, each unit cell 4 constituting the laminated cell stack 2 has a communication hole 7 formed at a position corresponding to the communication hole 7b formed in each electrode 19a, 19b. Of these, the communicating holes 7 of the separator 6 are formed in the outer periphery corresponding to the communicating holes 7 of the membrane electrode assembly 5. In addition, the communicating holes of the membrane electrode assembly 5 are formed in a resin frame provided on the outer periphery, and are formed in positions corresponding to the communicating holes 7 of the separator 6. These communication holes 7 are arranged at positions that do not overlap with the membrane electrode assemblies 5 a of the membrane electrode structure 5 . Furthermore, multiple unit cells 4 are stacked in the stacking direction W and sandwiched between an electrode 19a on the inlet portion 11 side and an electrode 19b on the closing portion 12 side. This forms a stacked cell stack 2. The stacked cell stack 2 aligns each of the communication holes 7 in the stacking direction W to form the distribution paths 10c of the fluid manifold 10. The distribution paths 10c are passages that distribute and supply the fluid H to each of the unit cells 4 corresponding to each position in the stacking direction W.

[0016] The fluid manifold 10 also has an inlet-side distribution path 10d on the inlet section 11 side of the distribution path 10c in the stacking direction W. The fluid manifold 10 also has a blocked-side area 10e on the blocked section 12 side. The distribution path 10c is connected to the inlet-side distribution path 10d and the blocked-side area 10e, thereby communicating the internal spaces thereof.

[0017] Fluid passages 20 for flowing fuel gas are provided between the membrane electrode assembly 5 and the separators 6. Fluid passages 20 for flowing refrigerant are also provided between the unit cells 4 (i.e., between the separators 6). The unit cells 4 have connecting paths 13 that connect the through-holes 7 (i.e., the fluid manifolds 10) and the fluid passages 20.

[0018] Three supply communication holes corresponding to two gases and one refrigerant are formed in the separator 6 and frame member 5b of the unit cell 4. The three communication holes communicate with each other in the stacking direction, forming three fluid manifolds in the stacked cell stack 2. In this embodiment, as shown in FIG. 1, the fluid manifold 10 for supplying fluid H to the fluid passage 20 between the membrane electrode assembly 5 and the right separator 6 has been described as an example, but the other two fluid manifolds have the same structure, so their description will be omitted.

[0019] In the manifold structure of the fuel cell of the first embodiment, as shown in Fig. 6, an external manifold 31 is connected to the case inlet 3d of the inlet end frame 3b. Also, on the opposite side of the active region 8 from the fluid manifold 10, a discharge-side internal manifold 30 is provided, which communicates with the fluid manifold 10 via a fluid passage 20. Furthermore, a discharge-side external manifold 32, which is one of the external fluid passages, is connected to the case outlet 3e of the inlet end frame 3b. The fluid flowing down the fluid passages 20 from the vicinity of the active region 8 is collected in the discharge-side internal manifold 30 and is discharged in the direction of the discharge-side external manifold 32 on the outside.

[0020] Next, the biasing portion 9 formed in the inlet portion 11 will be described using FIG. 2 while referring to FIG. A piping side insulator 15 and a cell side inlet insulator 16 provided on the inlet side end unit are arranged in the inlet section 11. The piping side insulator 15 and the cell side inlet insulator 16 are stacked in the stacking direction W so that their openings are aligned.

[0021] The biasing portion 9 of the first embodiment has a tapered surface 9a formed on the inner wall surface of the piping-side insulator 15. The tapered surface 9a is formed on the inner wall 11b on the side opposite to the connecting passage 13 side, and is inclined at an inclination angle α so as to approach the connecting passage 13 side from the inlet 11a side toward the blocking portion 12 side. In the biasing portion 9 of the first embodiment, the inclination angle α of the tapered surface 9a is set to, for example, three degrees. This allows the inlet portion 11 in which the biasing portion 9 is formed to bias the fluid H flowing into the fluid manifold 10 toward the connecting passage 13 side.

[0022] Moreover, the biasing portion 9 of the first embodiment has a straight surface 9b on the inner wall 11b of the inlet portion 11. The straight surface 9b is provided on the connection path 13 side of the inner wall surface of the piping-side insulator 15. The straight surface 9b is provided on the active region 8 side and is formed parallel to the direction of the central axis L of the fluid manifold 10. As a result, the inner wall surface of the inlet portion 11 has an asymmetric shape between the top and bottom surfaces.

[0023] 4, in the biasing portion 9 of the first embodiment, the cross section of the inlet portion 11 of the fluid manifold 10 is circular. Also, as shown in FIG. 2, the inner diameter dimension of the end portion 15a of the piping-side insulator 15 on the blocking portion 12 side is smaller than the inner diameter dimension d1 of the inlet portion 11.

[0024] In addition, the center S2 of the end of the biasing portion 9 on the blocking portion 12 side is eccentric toward the connecting path 13. For this reason, as shown in Fig. 3, the circular center line SL connecting the center S1 on the inlet 11a side and the center S2 on the blocking portion 12 side is inclined so as to approach the connecting path 13 side as it moves from the inlet 11a side toward the blocking portion 12 side.

[0025] Furthermore, in the first embodiment, an expanded diameter portion 16a is provided by utilizing the inner wall surface of the cell-side inlet insulator 16 located in the inlet portion 11. The expanded diameter portion 16a in the first embodiment has a lower inner wall surface 16c on the active region 8 side and an upper inner wall surface 16b on the opposite side. The upper inner wall surface 16b and the lower inner wall surface 16c are formed symmetrically, with their diameters expanding at the same rate toward the blocking portion 12. As a result, the pressure and flow rate of the fluid H flowing from the biasing portion 9 of the pipe-side insulator 15 into the fluid manifold 10 decreases when passing through the expanded diameter portion 16a of the pipe-side insulator 15. The end of the expanded diameter portion 16a on the closed portion 12 side has the largest inner diameter dimension d2, and is connected to and communicates with the fluid manifold 10 having the same inner diameter dimension d2.

[0026] Also, as shown in Figure 1, the blocking portion 12 of the first embodiment is formed by stacking a blocking portion side end frame 3c provided in the stack case 3, an end frame side insulator 18, a cell side insulator 17, and an electrode 19b in this order from the outside to form a blocking portion side end unit.

[0027] In the first embodiment, the diameter of the expanded diameter portion 16a expands at the same rate on the upper inner wall surface 16b and the lower inner wall surface 16c. Furthermore, the end of the expanded diameter portion 16a on the closure portion 12 side, which has the largest inner diameter dimension d2, is connected to the fluid manifold 10, which has the same inner diameter dimension. Therefore, the pressure and flow velocity of the fluid H passing through the biasing portion 9 can be reduced while maintaining the flow direction so that the fluid approaches the connection path 13 as it moves toward the closure portion 12 side.

[0028] 1, the blocking section 12 of the first embodiment is provided with a blocking section-side end unit. The blocking section-side end unit has, from the electrode 19b side toward the outside, a cell-side insulator 17, an end-frame-side insulator 18, and a blocking section-side end frame 3c attached to the housing 3a of the stack case 3, and is stacked in the stacking direction W.

[0029] In the first embodiment, the cell-side insulator 17 is formed with an opening 12a of a predetermined depth h1 that communicates with the distribution passage 10c of the fluid manifold 10. The distribution passage 10c extends an internal communicating space portion to the closed-side area 10e formed within the opening 12a. As a result, the other end 10b on the closed-side side of the fluid manifold 10 becomes an inner wall that faces the closed-side area 10e of the end-frame-side insulator 18.

[0030] Therefore, the fluid H flowing in the fluid manifold 10 toward the occluding section 12 flows from the opening 12a toward the occluding section-side end frame 3c. In the occluding side area 10e, the fluid H hits the inner wall of the end frame-side insulator 18, bounces off, and flows back in the opposite direction toward the inlet section 11. As a result, the fluid H forms a single flow that turns back in an approximately U-shape in the longitudinal direction within the fluid manifold, and a fluid with a stable static pressure distribution circulates within the blocked area 10e. Therefore, the static pressure distribution of the fluid H supplied to the unit cells 4 of the laminated cell stack 2 is made uniform, further improving the power generation efficiency.

[0031] Furthermore, the stacked cell stack 2 of the first embodiment is provided with a plurality of dummy cells 14 on the inlet portion 11 side or the closed portion 12 side in the stacking direction W. The dummy cells 14 regulate the temperature of the stacked cell stack 2. For this reason, the dummy cells 14 are stacked in the stacking direction W, interposed between the electrodes 19a, 19b and the unit cells 4 on the outside of the unit cells 4 located on the inlet portion 11 side of the connecting path 13 and the closed portion 12 side. These dummy cells 14 do not generate electricity even when fluid H is supplied to the surrounding area, since they do not undergo a hydrogen oxidation reaction or an oxygen reduction reaction. Dummy cells 14 are placed near the inlet-side distribution path 10d or the blocked-side area 10e, where the static pressure distribution is less stable at both ends of the distribution path 10c of the fluid manifold 10. As a result, the fluid H, which has a disturbed static pressure distribution, is distributed to the dummy cells 14 via the respective connecting paths. Therefore, a fluid with a stable static pressure distribution and less disturbance is distributed to the unit cells 4 located between the dummy cells 14, 14 on both sides. This further improves power generation efficiency.

[0032] In the manifold structure of the fuel cell of the first embodiment configured as described above, as shown in FIG. 2, the straight surface 9b provided on the inner wall 11b by the biasing portion 9 of the inlet portion 11 is parallel to the central axis L of the fluid manifold 10, and the tapered surface 9a of the inner wall 11b on the side opposite to the connection path 13 is inclined at an inclination angle α of 3 degrees so as to approach the connection path 13 side as it moves from the inlet 11a side toward the blocking portion 12. Therefore, when the fluid H on the connection path 13 side passing through the inlet portion 11 flows into the distribution path 10c toward the blocking portion 12 side, it is biased toward the connection path 13 side as it moves from the inlet 11a side toward the blocking portion 12.

[0033] That is, in the first embodiment, the flow rate of the fluid H flowing into the fluid manifold 10 at a position close to the connection path 13 increases. Furthermore, the flow rate relatively decreases at a position away from the connection path 13. This makes it possible to shift the timing at which the flow of the fluid H bounces back at the closed portion 12 at the other end 10b located on the opposite side of the inlet portion 11. 3, the fluid H that bounces off the occluded portion 12 at the other end 10b can pass by the fluid H heading toward the occluded portion 12 without interfering with it. Therefore, the generation of turbulence near the occluded portion 12 is suppressed. In this way, the fluid manifold 10 of the first embodiment suppresses the occurrence of turbulence in the blocked side area 10e close to the blocked section 12, and allows the fluid to smoothly return toward the inlet section 11 at a position away from the connecting path 13.

[0034] Moreover, near the inlet portion 11, the flow rate of the fluid H flowing into the fluid manifold 10 is lower on the opposite side than on the connecting path 13 side due to bias. Furthermore, in the first embodiment, the diameter of the inlet portion 11 side of the fluid manifold 10 is expanded by the expanded diameter portion 16a of the cell-side inlet insulator 16. Therefore, the pressure and flow velocity of the fluid H that separates from the upper inner wall surface 16b are reduced. Therefore, the fluid H that returns toward the vicinity of the inlet portion 11 is caught up in and merges with the fluid H that flows toward the connecting path 13 at a higher flow rate.

[0035] For example, if the expanded diameter portion 16a shown in FIG. 2 is provided as in the first embodiment, a large longitudinal vortex flow (tumble flow) that swirls vertically along the stacking direction W of the communicating hole 7 can be generated. This results in a good flow distribution at each location in the stacking direction W, including the flow of the rebounded fluid H. Therefore, the fluid H that flows from the connecting path 13 into the fluid passage 20 is supplied evenly to each unit cell 4. This further equalizes the flow rate distribution of the fluid H supplied to the membrane electrode assemblies 5a of each membrane electrode structure 5, and each unit cell 4 generates electricity equally. Therefore, by employing the manifold structure of this embodiment, the fuel cell 1 can stabilize the output voltage with a simple configuration and obtain good power generation efficiency.

[0036] 5, the fluid H that flows into the fluid manifold 10 flows straight toward the occluded portion 12 evenly. Therefore, near the occluded portion 12, even if the fluid H flowing toward the occluded portion 12 is a swirl flow, it interferes with the rebounding fluid H, causing turbulence and hindering smooth flow. Therefore, the static pressure distribution within the fluid manifold 10 is disturbed, and the amount of fluid supplied to each unit cell 4 cannot be made uniform.

[0037] 2, the manifold structure of the fuel cell of the first embodiment can increase the flow rate of the fluid H at a position close to the connection path 13 and relatively decrease the flow rate at a position away from the connection path 13. Therefore, as shown in FIG. 3, the fluid H that bounces off the blocking portion 12 passes by the fluid H heading toward the blocking portion 12, reducing the risk of interference. Therefore, the generation of turbulence near the blocking portion 12 is suppressed. Accordingly, at a position away from the connecting passage 13 side, the fluid H smoothly returns toward the inlet portion 11 side, forming a large longitudinal vortex flow (tumble flow). The tumble flow has characteristics of a longitudinal vortex flow that are clearly different from a swirl flow, which has the same flow rate whether close to or far from the connecting passage 13 side. The longitudinal vortex flow increases the flow rate in the stacking direction W on the connection path 13 side, stabilizing the static pressure distribution in the distribution path 10c. This makes it possible to uniformize the amount of fluid supplied to the unit cells 4 at each position in the stacking direction W, thereby improving power generation efficiency.

[0038] 7 is a graph comparing the static pressures a and d when the biasing section 9 is not provided at the inlet of the fluid manifold 10 with the static pressures b and d when the biasing section 9 of the first embodiment is provided. For this reason, in FIG. 7, the change in static pressure from the inlet section 11 side (Wet End) to the blocked section 12 side (Dry End) is measured along the stacking direction W of the unit cells 4. The static pressures a and b in this graph were measured at various locations from the inlet 11 side of the fluid manifold 10 shown in Figure 6 toward the blocked section 12. The static pressures 1 and d in Figure 7 were measured at various locations from the blocked section 12 side of the discharge-side internal manifold 30 toward the case outlet 3e in Figure 6.

[0039] 7 shows that the static pressure b when the biasing section 9 of the first embodiment is provided is stable with little fluctuation compared to the static pressure a when the biasing section 9 is not provided at the inlet of the fluid manifold 10. In particular, in the first embodiment, the static pressure on the blocking section 12 side is stable.

[0040] Furthermore, the shape of the parts needs to be changed only by changing the shape of the inner wall surfaces of the piping side insulator 15 and the cell side inlet insulator 16 that are separable at the inlet portion 11 of the fluid manifold 10 . Therefore, it is possible to use unit cells 4 and stacked cell stacks 2 with the same shapes as other fuel cells, for example, and the effect can be achieved without incurring additional costs by simply setting the shape of the inlet portion 11. Therefore, there is no need to change the shape of the active region 8 in which the membrane electrode structure 5 having the membrane electrode assembly 5a is disposed, or the stacked cell stack 2. This eliminates the need to change the design for each fuel cell 1, and reduces the number of parts, thereby suppressing increases in manufacturing costs.

[0041] 7, it can be seen that the static pressure (I, d) in the discharge-side internal manifold 30 is not affected when the biasing section 9 is formed compared to when the biasing section 9 is not formed. Therefore, there is no need to change the shape of the laminated cell stack 2 or the discharge-side external manifold 32.

[0042] The biasing portion 9 of the first embodiment is formed by being divided into two members: a pipe-side insulator 15 and a cell-side inlet insulator 16 disposed adjacent to it. Therefore, even if the shape of the biasing portion 9 is complex, it can be easily manufactured by processing each part individually. For example, when manufacturing the parts of the biasing portion 9 by cutting, by processing two members separately, it is possible to reduce undercut portions and also to accommodate complex shapes.

[0043] 8 is a vertical cross-sectional view illustrating the configuration of bias portion 29 formed at the inlet of the fluid manifold in the manifold structure of the fuel cell according to the second embodiment. Note that parts that are the same as or equivalent to bias portion 9 of fluid manifold 10 according to the first embodiment are given the same reference numerals and descriptions thereof will be omitted. The biasing portion 29 of the second embodiment has a tapered surface 29b on the inner wall of the end frame side insulator 21 on the connecting passage 13 side. The tapered surface 29b is inclined so as to approach the connecting path 13 side toward the closed portion 12 (not shown), similar to the tapered surface 9a of the first embodiment.

[0044] In addition, in the second embodiment, the bias portion 29 is set so that the expansion rate of the expansion portion 22a, 22b of the cell side inlet insulator 22, which is located away from the connecting path 13 side, is greater than the expansion rate of the expansion portion 22b, which is located closer to the connecting path 13 side.

[0045] In the fuel cell manifold structure of the second embodiment configured as described above, in addition to the effect of the biasing portion 9 of the first embodiment, the tapered surface 29b is inclined so as to approach the connection path 13 side. Therefore, the fuel cell manifold structure of the second embodiment biases the flow toward the connection path 13 side, increasing the flow rate on the connection path 13 side, thereby speeding up the flow of fluid H1. Also, the flow of fluid H2 on the side opposite to the connection path 13 side can be slowed down to create a flow velocity difference. This makes it even easier to generate a longitudinal vortex flow (tumble flow) that flows in one direction within the fluid manifold 10 of the stacked cell stack 2 (not shown).

[0046] Furthermore, by increasing the diameter of the enlarged portion 22a located away from the connection path 13, the flow velocity of the fluid H2 on the side opposite to the connection path 13 can be further reduced. The other configurations and effects are the same as those of the first embodiment, so the description will be omitted.

[0047] 9 is a vertical cross-sectional view illustrating the configuration of bias portion 39 formed at the inlet portion of the manifold structure for a fuel cell according to the third embodiment. Note that parts that are the same as or equivalent to the bias portions 9, 29 of the fluid manifold 10 according to the first and second embodiments are given the same reference numerals and descriptions thereof will be omitted. The biasing section 39 of the third embodiment is formed by combining the piping side insulator 15 that constitutes the biasing section 9 of the first embodiment and the cell side inlet insulator 22 that constitutes the biasing section 29 of the second embodiment.

[0048] In the manifold structure of the fuel cell of the third embodiment configured as above, the following effects can be obtained in addition to the effects of the biasing portion 9 of the first embodiment. That is, the cell-side inlet insulator 22 of the third embodiment has a large diameter expansion at the expanded diameter portion 22a located away from the connecting passage 13. This further reduces the flow velocity of the fluid H3 on the side opposite to the connecting passage 13 side, and ensures the flow rate of the fluid H1 entering the unit cell 4 while pushing the flow of the fluid H1 on the connecting passage 13 side. Therefore, the inlet side (Wet End) of the fluid manifold 10 exhibits a practically beneficial effect of being able to ensure the desired flow rate even when the flow velocity is high and the flow rate flowing into the unit cell 4 tends to be low. The other configurations and effects are the same as those of the first embodiment, so the description will be omitted.

[0049] As described above, the manifold structure for a fuel cell according to the present invention includes a stacked cell stack 2 having an active region formed by stacking a plurality of unit cells 4, each having a membrane electrode assembly 5 and a separator 6. The manifold structure also includes a stack case 3 that houses the stacked cell stack 2. The manifold structure also includes a fluid manifold 10 that extends in the stacking direction W of the unit cells 4 of the stacked cell stack 2, connecting the communication holes 7 formed in each unit cell 4, and supplies fluid H to each unit cell 4. Each unit cell 4 has a fluid passage 20 formed between the membrane electrode assembly 5 and the separator 6, and a connection path 13 that connects the communication holes 7 to the fluid passage 20. The fluid manifold 10 has an inlet portion 11 at one end 10a that communicates with the outside of the stack case 3 and has an inlet 11a for allowing fluid H to flow in, and a blocking portion 12 located at the other end 10b opposite the inlet portion 11. The inlet portion 11 is provided with a biasing portion 9 that biases the fluid H flowing into the fluid manifold 10 toward the connecting path 13 side.

[0050] The manifold structure of the fuel cell of the present invention configured as above can improve the power generation efficiency with a simple structure. Specifically, the biasing portion 9 biases the fluid H flowing into the fluid manifold 10 from the inlet portion 11 toward the connecting path 13, thereby increasing the flow rate. As a result, the flow rate of the fluid H decreases on the side opposite the connecting path 13. Therefore, the fluid H that bounces off the blocking portion 12 at the other end 10b can reduce interference with the fluid H heading toward the blocking portion 12, and the generation of turbulence near the blocking portion 12 is suppressed.

[0051] The fluid H, whose direction of flow has been reversed at the blocking portion 12, smoothly returns toward the inlet portion 11. Therefore, near the inlet portion 11 in the fluid manifold 10, the flow rate of the inflowing fluid H is large, and the static pressure increases due to the returning fluid H. This stabilizes the static pressure distribution in the areas corresponding to each unit cell 4 in the direction in which the unit cells 4 of the laminated cell stack 2 are stacked. In this way, when the static pressure difference between the inlet portion 11 side and the blocked portion 12 side is improved, it is possible to equalize the amount of fluid H supplied to the fluid passage 20 via the connecting path 13. Therefore, it is possible to use unit cells 4 of the same shape without increasing the size of the parts or changing their shape, and it is possible to improve the power generation efficiency by simply setting the shape of the inlet portion 11 at no cost.

[0052] The biasing portion 9 is formed on the inner wall 11b of the inlet portion 11 and has a tapered surface 9a that is inclined so as to approach the connecting passage 13 side as it moves from the inlet 11a side toward the blocking portion 12 side. The tapered surface 9a of the biasing portion 9 can efficiently bias the fluid H flowing into the fluid manifold 10 from the inlet portion 11, thereby further increasing the flow rate on the connection path 13 side. The tapered surface 9a can be easily formed on the inner wall 11b of the inlet portion 11. Furthermore, there is no need to change the shape or structure of the laminated cell stack 2 in which the fluid passages 20 and the active regions 8 are provided. Furthermore, when connecting other components such as the external manifold 31 to the inlet 11a of the inlet portion 11, there is no need to change the shape in accordance with the increase in size as in the past.

[0053] Furthermore, the biasing portion 9 has a straight surface 9b provided on the inner wall 11b of the inlet portion 11 on the connecting passage 13 side, which is parallel to the direction of the central axis L of the fluid manifold 10. The straight surface 9b of the biasing portion 9 can be easily formed on the inner wall 11b of the inlet portion 11. Then, the fluid H can be smoothly supplied to the connecting passage 13 side along the straight surface 9b. This further maintains the biased flow rate on the connection side, and by shifting the timing of the fluid H reaching the blocking section 12 side, the flow rate distribution in the stacking direction W can be improved, including the rebounded flow.

[0054] The inlet portion 11 of the fluid manifold 10 has a circular center line SL, which is the center line connecting the center S1 on the inlet 11a side and the center S2 on the blocked portion 12 side, inclined so that it approaches the connecting path 13 side as it moves from the inlet 11a side to the blocked portion 12 side. This allows the fluid H to flow inside the inlet portion 11 in the direction of the circle center line SL, further increasing the flow rate on the connection path 13 side.

[0055] Further, the biasing portion 9 is set so that the size of the passage cross-sectional area on the inlet 11a side of the inlet portion 11 is smaller than the size of the passage cross-sectional area on the closed portion 12 side of the inlet portion 11. As a result, the biasing portion 9 can separate the fluid H passing through the inlet portion 11 from the inner wall 11b of the inlet portion 11, thereby reducing the pressure.

[0056] Therefore, the fluid returning toward the inlet portion 11 smoothly merges with the flow on the connecting path 13 side from the inlet portion 11 toward the closed portion 12, generating a large longitudinal vortex flow. This makes it possible to further equalize the static pressure distribution of the fluid H in the fluid manifold 10 from the inlet portion 11 side to the closed portion 12 side, thereby reducing the bias in the flow rate. In this way, the manifold structure of the fuel cell of the present invention has a simple configuration with a bias portion 9 provided at the inlet portion 11, and exhibits practically beneficial effects such as being able to easily improve power generation efficiency without changing the shape or size of other components.

[0057] The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are provided as examples to facilitate understanding of the present invention, and are not necessarily limited to those including all of the configurations described. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Possible modifications of the above-described embodiments include, for example, the following.

[0058] For example, in the embodiment, the biasing portion 9 is formed by being divided into two members, a pipe-side insulator 15 and a cell-side inlet insulator 16 disposed adjacent to it. However, the present invention is not limited to this, and the biasing portion may be formed using a single insulator, for example. In other words, as long as the biasing portion 9 is provided in the components that make up the inlet portion 11, the shape, quantity, material, and number of components of the biasing portion 9 are not limited.

[0059] Furthermore, in the stacked cell stack 2 of the embodiment, a plurality of dummy cells 14 are provided on the inlet portion 11 side or the closed portion 12 side in the stacking direction W. However, the manifold structure of the fuel cell of the present invention is not particularly limited to this, and the dummy cells 14 do not have to be provided. [Explanation of symbols]

[0060] 1 fuel cell 2. Layered cell stack 4 Unit Cell 5 Membrane electrode structure 6 Separator 9,29,39 eccentric part 9a Tapered surface 10 Fluid Manifold 10a one end 10b other end 11 Entrance 11a Entrance 11b Medial wall 12 Occlusion 13 Connecting Road 20 Fluid passage

Claims

1. a stacked cell stack in which an active region is formed by stacking a plurality of unit cells each having a membrane electrode assembly and a separator; a stack case that houses the laminated cell stack; a fluid manifold extending in a stacking direction of the unit cells of the stacked cell stack to communicate with the communication holes formed in each of the unit cells and supplying a fluid to each of the unit cells, the unit cell has a fluid passage provided between the membrane electrode assembly and the separator, and a connection path connecting the communication hole and the fluid passage, the fluid manifold has an inlet portion provided at one end communicating with the outside of the stack case with an inlet for allowing fluid to flow in, and a closing portion located at the other end opposite the inlet portion, 10. A manifold structure for a fuel cell, wherein the inlet portion is provided with a biasing portion that biases the fluid flowing into the fluid manifold toward the connecting path.

2. 2. The fuel cell manifold structure according to claim 1, wherein the biasing portion is formed on an inner wall of the inlet portion and has a tapered surface that slopes toward the active region as it moves from the inlet side toward the blocking portion side.

3. 3. A manifold structure for a fuel cell as described in claim 1 or 2, characterized in that the biasing portion has a straight surface on the inner wall of the inlet portion, on the connection path side, that is parallel to the direction of the central axis of the fluid manifold.

4. 2. The manifold structure of a fuel cell according to claim 1, wherein the inlet portion of the fluid manifold has a center line connecting the center of the inlet side and the center of the blocked portion side that is inclined so as to approach the connection path side as it moves from the inlet side to the blocked portion side.

5. 2. The manifold structure for a fuel cell according to claim 1, wherein the biasing portion is configured so that the cross-sectional area of ​​the passage on the inlet side of the inlet portion is smaller than the cross-sectional area of ​​the passage on the closed portion side of the inlet portion.

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