Fuel cell stack
The fuel cell stack design uses pockets and narrow grooves to manage water accumulation in outlet channels, addressing blockage issues and ensuring reliable power generation by effectively discharging water and gases.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-12-12
- Publication Date
- 2026-06-24
AI Technical Summary
In conventional fuel cells, water generated during power generation can accumulate in outlet flow path grooves due to capillary action, leading to blockage and hindering the discharge of reaction gases and water, which can cause power generation failure or restart issues.
The fuel cell stack design incorporates pockets formed by gaps between adjacent cells and positioned on the gravity side of outlet connection channels, featuring narrow grooves and additional side portions to draw water into these pockets using capillary action, preventing accumulation in outlet channels and enhancing discharge efficiency.
This design effectively prevents outlet channel blockage, reduces the need for scavenging treatments, and ensures continuous and restartable power generation by efficiently managing water discharge.
Smart Images
Figure 2026103011000001_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a fuel cell stack.
Background Art
[0002] Conventionally, a fuel cell is known that includes a membrane electrode gas diffusion layer assembly and a pair of separators that sandwich the membrane electrode gas diffusion layer assembly (Patent Document 1). This fuel cell has a gas flow path portion for allowing a reaction gas to flow between the membrane electrode gas diffusion layer assembly and the separator, and a manifold for allowing the reaction gas to flow through the fuel cell. The gas flow path portion has a main flow path portion facing the membrane electrode gas diffusion layer assembly and a connection flow path portion connecting the main flow path portion and the manifold. A plurality of flow path grooves for forming a plurality of outlet flow paths are provided in the connection flow path portion.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In a fuel cell, water is generated during the process of supplying a reaction gas to a membrane electrode gas diffusion layer assembly and generating electricity through an electrochemical reaction. The water generated in the fuel cell during power generation passes through the outlet flow path together with the reaction gas not used for power generation and is discharged from the manifold to the outside of the fuel cell. In the conventional technology, there is a risk that the water generated in the fuel cell during power generation is sucked into the flow path groove due to capillary action, water accumulates in the flow path groove, and the outlet flow path is blocked.
Means for Solving the Problems
[0005] This disclosure can be realized in the following forms.
[0006] (1) According to one embodiment of the present disclosure, a fuel cell stack is provided. The fuel cell stack, in which a plurality of fuel cell cells are stacked, comprises a plate member having a membrane electrode gas diffusion layer assembly and a resin sheet holding the outer periphery of the membrane electrode gas diffusion layer assembly, a separator facing the plate member, a flow path for circulating fluid between the plate member and the separator, and an outlet manifold for discharging the fluid to the outside of the fuel cell, wherein the flow path comprises a main flow path facing the membrane electrode gas diffusion layer assembly and a connecting flow path connecting the main flow path and the outlet manifold, The fuel cell stack has a resin sheet and a connecting channel section facing it, the connecting channel section having a plurality of channel grooves that form a plurality of outlet channels, and the fuel cell stack has a pocket that communicates with the channel grooves and is formed by the gap between adjacent fuel cell cells, and is located on the gravity side of the connecting channel section in the installation position of the fuel cell stack, and the pocket has a first side portion formed by a narrow groove that extends from the lower end of the connecting channel section on the gravity side of the connecting channel section in the installation position, and has a smaller cross-sectional area than the channel grooves. With this configuration, water accumulated in the channel grooves can be drawn into the pocket by capillary action. This prevents water generated in the fuel cell cells during power generation from accumulating in the channel grooves and blocking the outlet channels. (2) In the above configuration, the pocket may further have a bottom portion connected to the first side portion and positioned on the gravity side of the narrow groove in the installation position, and a second side portion extending from the end of the bottom portion opposite to the end connected to the narrow groove on the anti-gravity side of the bottom portion in the installation position. In this configuration, water can be stored in the pocket by providing the bottom portion. This prevents water drawn in from the narrow groove from returning to the flow channel groove side. Therefore, the blockage of the outlet flow channel can be further suppressed. Furthermore, by providing the second side portion, even more water can be stored in the pocket. This makes it possible to more reliably prevent water drawn in from the narrow groove from returning to the flow channel groove side. Therefore, the blockage of the outlet flow channel can be further suppressed. (3) In the above configuration, at least a portion of the outlet manifold may be positioned on the gravity side of the connecting flow path portion in the installation position, and at least a portion of the pocket may be formed by the inner wall of the outlet manifold. In this configuration, by positioning at least a portion of the outlet manifold on the gravity side of the connecting flow path portion in the installation position of the fuel cell stack, at least a portion of the pocket can be formed by the inner wall of the outlet manifold. (4) In the above configuration, the flow path portion includes an anode flow path portion for circulating fuel gas between the plate member and the anode separator as a separator, and the fuel cell stack may include at least the pocket that communicates with the flow path groove provided in the connecting flow path portion of the anode flow path portion. With this configuration, it is possible to suppress the blocking of the outlet flow path on the anode side, which is more prone to blockage than the cathode side. (5) In the above configuration, the fine groove may have irregularities over its entire surface. With this configuration, water accumulated in the flow channel groove can be drawn into the pocket more reliably, thereby further suppressing blockage of the outlet flow channel. This disclosure can be implemented in various forms other than the fuel cell stack described above. For example, it can be implemented in the form of a fuel cell stack manufacturing method, a vehicle equipped with a fuel cell stack, etc. [Brief explanation of the drawing]
[0007] [Figure 1] A diagram showing the schematic configuration of a fuel cell stack. [Figure 2] Exploded perspective view of a fuel cell. [Figure 3] Figure 1 illustrates the details of the outlet channel in the anode channel section. [Figure 4] Figure 2 illustrates the details of the outlet channel in the anode channel section. [Figure 5] A diagram showing an example of a pocket. [Figure 6] A diagram showing the detailed configuration of the pockets. [Figure 7] A diagram showing other examples of pockets. [Modes for carrying out the invention]
[0008] A. Embodiments: Figure 1 shows a schematic configuration of a fuel cell stack 1. The fuel cell stack 1 generates electricity through an electrochemical reaction by receiving a fuel gas such as hydrogen and an oxidizer gas such as air. The fuel cell stack 1 has a stack structure in which multiple fuel cell cells 100 are stacked.
[0009] Figure 2 is an exploded perspective view of the fuel cell cell 100. The X direction is along the longitudinal direction of the fuel cell cell 100. The Y direction is along the short direction of the fuel cell cell 100. The Z direction is along the thickness direction of the fuel cell cell 100 and is the stacking direction DL of the multiple fuel cell cells 100. In this embodiment, when the fuel cell stack 1 is installed on an object such as a vehicle, the +Y direction is the anti-gravity direction and the -Y direction is the gravity direction. The same applies to the figures and descriptions shown thereafter.
[0010] The fuel cell cell 100 comprises a plate member 10, and an anode separator 20 and a cathode separator 30 that face the plate member 10 and sandwich the plate member 10. The plate member 10 has a membrane electrode gas diffusion layer assembly 11 (MEGA) and a resin sheet 12.
[0011] The membrane electrode gas diffusion layer assembly 11 comprises a membrane electrode assembly (MEA). The membrane electrode assembly comprises an electrolyte membrane, an anode catalyst layer disposed on one side of the electrolyte membrane, and a cathode catalyst layer disposed on the other side of the electrolyte membrane. The electrolyte membrane selectively permeates specific ions. The anode catalyst layer catalyzes an electrochemical reaction on the anode side. The cathode catalyst layer catalyzes an electrochemical reaction on the cathode side. The membrane electrode gas diffusion layer assembly 11 further comprises an anode gas diffusion layer disposed opposite the anode catalyst layer and a cathode gas diffusion layer disposed opposite the cathode catalyst layer. The anode gas diffusion layer diffuses fuel gas and supplies it to the anode catalyst layer. The cathode gas diffusion layer diffuses oxidizer gas and supplies it to the cathode catalyst layer.
[0012] The resin sheet 12 is a rectangular frame. The resin sheet 12 has an opening 13 in the center. The outer periphery 11r of the membrane electrode gas diffusion layer assembly 11 is bonded to the opening 13 of the resin sheet 12 with adhesive. In this way, the resin sheet 12 holds the outer periphery 11r of the membrane electrode gas diffusion layer assembly 11.
[0013] Each separator 20, 30 separates the plate member 10 from other fuel cell cells 100. Each separator 20, 30 has gas surfaces 20g, 30g and cooling surfaces 20c, 30c. The gas surfaces 20g, 30g are the surfaces that come into contact with the reaction gas. The cooling surfaces 20c, 30c are the surfaces that come into contact with the coolant and are the surfaces opposite to the gas surfaces 20g, 30g.
[0014] The resin sheet 12 and each of the separators 20 and 30 each have manifolds 41-46 for fluid circulation. The manifolds 41-46 are holes formed in the main body portions 21 and 31 of the resin sheet 12 and each of the separators 20 and 30. Each of the manifolds 41-46 is formed at a position overlapping with each other in the stacking direction DL of the plurality of fuel cell units 100. Thereby, the fuel gas is distributed to the anode side of the fuel cell unit 100, the oxidant gas is distributed to the cathode side of the fuel cell unit 100, and the coolant for cooling the fuel cell unit 100 is distributed between adjacent fuel cell units 100.
[0015] Specifically, the fuel gas is supplied to the fuel gas inlet manifold 41. The fuel gas supplied to the fuel gas inlet manifold 41 is distributed to the anode side of each fuel cell unit 100 and flows through the anode flow path portion 50 formed between the plate member 10 and the gas surface 20g of the anode separator 20. Among the fuel gas distributed to the anode side, the fuel gas not used for power generation is discharged from the fuel gas outlet manifold 46 to the outside of the fuel cell stack 1. The fuel gas discharged to the outside of the fuel cell stack 1 is supplied again to the fuel gas inlet manifold 41.
[0016] The oxidant gas is supplied to the oxidant gas inlet manifold 44. The oxidant gas supplied to the oxidant gas inlet manifold 44 is distributed to the cathode side of each fuel cell unit 100 and flows through the cathode flow path portion 60 formed between the plate member 10 and the gas surface 30g of the cathode separator 30. Among the oxidant gas distributed to the cathode side, the oxidant gas not used for power generation is discharged from the oxidant gas outlet manifold 43 to the outside of the fuel cell stack 1.
[0017] The coolant is supplied to the coolant inlet manifold 42. The coolant supplied to the coolant inlet manifold 42 is distributed between adjacent fuel cell units 100 in the stacking direction DL, and flows through a coolant flow path (not shown) formed between the cooling surfaces 20c of the anode separators 20 and the cooling surfaces 30c of the cathode separators 30 of adjacent fuel cell units 100. The coolant that has flowed between adjacent fuel cell units 100 is discharged from the coolant outlet manifold 45 to the outside of the fuel cell stack 1. The coolant discharged to the outside of the fuel cell stack 1 is supplied again to the coolant inlet manifold 42.
[0018] In the present embodiment, the outlet manifolds 43 and 46 for discharging the reaction gas to the outside of the fuel cell unit 100 are disposed on the gravity direction side of the inlet manifolds 41 and 44 for allowing the reaction gas to flow into the fuel cell unit 100. This makes it easier to discharge the water generated inside the fuel cell unit 100 during power generation from the outlet manifolds 43 and 46, and prevents the water generated inside the fuel cell unit 100 from accumulating inside the fuel cell unit 100 during power generation.
[0019] The anode flow path portion 50 and the cathode flow path portion 60 each have a main flow path portion 51, 61, an inlet connection flow path portion 53, 63, and an outlet connection flow path portion 55, 65.
[0020] The main flow path portions 51, 61 face the membrane electrode gas diffusion layer joined bodies 11. The main flow path portions 51, 61 have a plurality of main flow paths 510, 610 through which the reaction gas flows on the membrane electrode gas diffusion layer joined bodies 11. The plurality of main flow paths 510, 610 are each formed by main flow path grooves 22, 32 formed by bending each of the separators 20, 30 by pressing. The main flow path grooves 22, 32 project from the main body portions 21, 31 toward the cooling surfaces 20c, 30c from the gas surfaces 20g, 30g. In the present embodiment, a plurality of main flow path grooves 22, 32 are formed in parallel at a predetermined interval. Thereby, the reaction gas travels straight through the main flow paths 510, 610. That is, in the present embodiment, the main flow paths 510, 610 are linear straight flow paths.
[0021] The outlet connection channel sections 55 and 65 connect the main channel sections 51 and 61 to the outlet manifolds 43 and 46. The outlet connection channel sections 55 and 65 face the resin sheet 12. The outlet connection channel sections 55 and 65 have a plurality of outlet channels 550 and 650 that allow fluid to flow from the main channel sections 51 and 61 to the outlet manifolds 43 and 46. The outlet channels 550 and 650 are formed by the slits 15 and 16 of the resin sheet 12 and the outlet channel grooves 25 and 35 of the separator 20. One end of the outlet channel grooves 25 and 35 is connected to the slits 15 and 16. The other end of the outlet channel grooves 25 and 35 is connected to the outlet manifolds 43 and 46.
[0022] Figure 3 is the first diagram illustrating the details of the outlet channel 550 in the anode channel section 50. Figure 3 shows the III-III cross-section in Figure 2. Figure 4 is the second diagram illustrating the details of the outlet channel 550 in the anode channel section 50. Figure 4 shows the IV-IV cross-section in Figure 2. As shown in Figure 2, the resin sheet 12 further has a plurality of perforated slits 15 between the membrane electrode gas diffusion layer assembly 11 and the fuel gas outlet manifold 46. As a result, the fluid that has flowed through the main channel 510 of the anode channel section 50 flows into the outlet channel 550 through the slits 15 in the resin sheet 12 formed between the membrane electrode gas diffusion layer assembly 11 and the fuel gas outlet manifold 46. At this time, as shown in Figure 3, each surface 10a, 10c of the resin sheet 12 is in contact with the gas surfaces 20g, 30g of each separator 20, 30, except for the parts where the slits 15 are formed. Therefore, the fluid flowing in from the slit 15 flows through the space surrounded by the resin sheet 12 and the gas surfaces 20g and 30g of each separator 20 and 30. Furthermore, as shown in Figure 4, the anode separator 20 has a plurality of outlet flow channel grooves 25 formed by bending the anode separator 20 by press working between the slit 15 and the fuel gas outlet manifold 46. These outlet flow channel grooves 25 protrude from the main body 21 from the gas surface 20g toward the cooling surface 20c. Since the outlet flow channel grooves 25 are connected to the slit 15, the fluid that has flowed through the space surrounded by the resin sheet 12 and the gas surfaces 20g and 30g of each separator 20 and 30 flows through the space surrounded by the anode-facing surface 10a of the resin sheet 12 and the outlet flow channel grooves 25 of the anode separator 20. Since the outlet channel groove 25 is connected to the fuel gas outlet manifold 46, the fluid that flows through the space enclosed by the anode-facing surface 10a of the resin sheet 12 and the outlet channel groove 25 of the anode separator 20 is discharged outside the fuel cell cell 100 from the fuel gas outlet manifold 46. The configuration of the outlet channel 650 in the cathode channel section 60 is the same as the configuration of the outlet channel 550 in the anode channel section 50.
[0023] As shown in Figure 2, in this embodiment, multiple outlet channels 550 and 650 are formed parallel to each other at predetermined intervals between the membrane electrode gas diffusion layer assembly 11 and the outlet manifolds 43 and 46. As a result, the reaction gas flows through the comb-shaped narrow outlet channels 550 and 650 formed by the slits 15 and 16 of the resin sheet 12 and the outlet channel grooves 25 and 35 of each separator 20 and 30, and is discharged from the outlet manifolds 43 and 46.
[0024] The inlet connection channel sections 53 and 63 connect the main channel sections 51 and 61 to the inlet manifolds 41 and 44. The inlet connection channel sections 53 and 63 face the resin sheet 12. The inlet connection channel sections 53 and 63 have a plurality of inlet channels 530 and 630 that allow fluid to flow from the inlet manifolds 41 and 44 to the main channel sections 51 and 61. The inlet channels 530 and 630, like the outlet channels 550 and 650, are formed by slits 17 and 18 in the resin sheet 12 and inlet channel grooves 23 and 33 in the separators 20 and 30. One end of the inlet channel grooves 23 and 33 is connected to the slits 17 and 18. The other end of the inlet channel grooves 23 and 33 is connected to the inlet manifolds 41 and 44.
[0025] In this way, by providing slits 15-18 in the resin sheet 12 at the connecting channel sections 53, 55, 63, and 65, and allowing the space between the slits 15-18 to function as a bridge girder, the bending of the resin sheet 12 can be suppressed. This ensures that the inlet channels 530, 630 and the outlet channels 550, 650 are secured.
[0026] However, in the fuel cell cell 100, water is generated during the process of generating electricity through an electrochemical reaction when a reaction gas is supplied to the membrane electrode gas diffusion layer assembly 11. The water generated in the fuel cell cell 100 during power generation passes through the outlet channels 550 and 650 along with the reaction gas that was not used for power generation, and is discharged outside the fuel cell cell 100 from the outlet manifolds 43 and 46. As a result, water generated in the fuel cell cell 100 during power generation may be drawn into the outlet channel grooves 25 and 35 by capillary action, causing water to accumulate in the outlet channel grooves 25 and 35, and potentially blocking the outlet channels 550 and 650 formed by the outlet channel grooves 25 and 35. Furthermore, because water molecules attract each other, the water accumulated in the outlet channel grooves 25 and 35 attracts water present in the surrounding area, increasing the likelihood of blockage of the outlet channels 550 and 650. If the outlet passages 550 and 650 become blocked, it may not be possible to discharge water generated within the fuel cell cell 100 during power generation or reaction gases not used for power generation from the fuel cell cell 100 to the outside of the fuel cell cell 100. If water and reaction gases cannot be discharged to the outside of the fuel cell cell 100, it may not be possible to continue power generation by the fuel cell cell 100, or it may not be possible to restart power generation by the fuel cell cell 100 after power generation has stopped.
[0027] Therefore, when power generation by the fuel cell cell 100 is stopped, scavenging gas is supplied to the outlet channels 550 and 650 to perform scavenging treatment, which discharges water accumulated in the outlet channel grooves 25 and 35 using the gas pressure of the scavenging gas. However, if a large amount of water accumulates in the outlet channel grooves 25 and 35, the scavenging treatment may not be able to resolve the blockage of the outlet channels 550 and 650. In addition, depending on the installation environment and usage conditions of the fuel cell cell 100, such as when starting the fuel cell cell 100 at sub-zero temperatures, the water accumulated in the outlet channel grooves 25 and 35 may freeze, completely blocking the outlet channels 550 and 650. If the water accumulated in the outlet channel grooves 25 and 35 freezes and completely blocks the outlet channels 550 and 650, it is difficult to resolve the blockage of the outlet channels 550 and 650 by scavenging treatment. Therefore, the inventors of the present invention conceived of providing water-retaining pockets 70 and 80 on the gravity side of the outlet connection channel sections 55 and 65 when the fuel cell stack 1 is installed, thereby preventing water from accumulating in the outlet channel grooves 25 and 35 and blocking the outlet channels 550 and 650.
[0028] Figure 5 shows an example of a pocket 70. Figure 5 shows an enlarged view of region R in Figure 2, including the outlet connection channel 55 in the anode channel 50, and also shows the arrangement of the fuel gas outlet manifold 46a in the second embodiment. The fuel cell stack 1 communicates with the outlet channel groove 25 and includes a pocket 70 formed by the gap between adjacent fuel cell cells 100. In the installed position of the fuel cell stack 1, the pocket 70 is positioned on the gravity side of the outlet connection channel 55. In this embodiment, at least a portion of the pocket 70 is formed by the inner wall 460 of the fuel gas outlet manifold 46. Therefore, at least a portion of the fuel gas outlet manifold 46 is positioned on the gravity side of the outlet connection channel 55 in the installed position of the fuel cell stack 1. In other words, in order for the inner wall 460 of the outlet manifold 46 to form at least a portion of the pocket 70, the end 465 of the outlet manifold 46 in this embodiment is positioned shifted on the gravity side of the end 465a of the outlet manifold 46a in the second embodiment.
[0029] Figure 6 shows the detailed configuration of pocket 70. Figure 6 representatively shows approximately 2.5 fuel cell cells 100 around the fuel gas outlet manifold 46 of the fuel cell stack 1. In Figure 6, pocket 70 is shown with diagonal hatching. Pocket 70 has a first side portion 710, a bottom portion 730, and a second side portion 750.
[0030] The first side portion 710 is formed by a narrow groove 715 extending in the direction of gravity from the lower end 555, which is the end of the outlet connection channel portion 55 in the direction of gravity, when the fuel cell stack 1 is installed. The cross-sectional area of the narrow groove 715 is smaller than the cross-sectional area of the outlet channel groove 25. In this way, water accumulated in the outlet channel groove 25 can be drawn into the pocket 70 by utilizing capillary action. This prevents water from accumulating in all the outlet channel grooves 25 in the outlet connection channel portion 55 and blocking the outlet channel 550. Furthermore, since water has the property of attracting each other, the water flowing through the narrow groove 715 can draw in the water accumulated in the outlet channel groove 25, further suppressing the blocking of the outlet channel 550. The cross-sectional area of the narrow groove 715 may be, for example, 1.3 mm or less. The smaller the cross-sectional area of the narrow groove 715, the greater the capillary force of the narrow groove 715 can be. This allows water accumulated in the outlet channel groove 25 to be drawn more reliably into the pocket 70, thereby further suppressing blockage of the outlet channel 550. The cross-sectional area of the narrow groove 715 is not limited to the above and may be appropriately adjusted according to the configuration of the fuel cell stack 1, such as the thickness of the separators 20 and 30 and the cell pitch.
[0031] The bottom portion 730 is connected to the first side portion 710. In the installation position of the fuel cell stack 1, the bottom portion 730 is positioned on the gravity side of the narrow groove 715. This allows sufficient water to be stored in the pocket 70. This prevents the water drawn in from the narrow groove 715 from returning to the outlet channel groove 25. Thus, the blockage of the outlet channel 550 can be further suppressed. Furthermore, since the bottom portion 730 is formed by the inner wall 460 of the fuel gas outlet manifold 46, the water stored in the pocket 70 can be reliably discharged from the fuel gas outlet manifold 46 to the outside of the fuel cell stack 1. This further suppresses the blockage of the outlet channel 550.
[0032] The second side portion 750 extends from the bottom portion 730 in the anti-gravity direction, opposite to the end portion 732 of the bottom portion 730 that is connected to the narrow groove 715, when the fuel cell stack 1 is installed. This allows more water to be stored in the pocket 70. This makes it more reliable to prevent the water drawn in from the narrow groove 715 from returning to the outlet channel groove 25. Thus, the blockage of the outlet channel 550 can be further suppressed.
[0033] Furthermore, the smaller the flow rate of the reaction gas, the more difficult it is for the water accumulated in the outlet channel grooves 25 and 35 to be discharged by the gas pressure of the reaction gas, and the greater the possibility that the outlet channels 550 and 650 will become blocked. Generally, the flow rate of the fuel gas flowing through the anode channel section 50 is smaller than the flow rate of the oxidizer gas flowing through the cathode channel section 60. Therefore, the outlet channel 550 in the anode channel section 50 is more prone to blockage than the outlet channel 650 in the cathode channel section 60. In this embodiment, the fuel cell stack 1 is provided with a pocket 70 that communicates with the outlet channel groove 25 provided in the outlet connection channel section 55 of the anode channel section 50. In this way, it is possible to suppress the blockage of the anode side outlet channel 550, which is more prone to blockage than the cathode side.
[0034] According to the above embodiment, as shown in Figure 6, the fuel cell stack 1 is provided with a pocket 70 that communicates with the outlet channel groove 25 of the outlet connection channel 55, located on the gravity side of the outlet connection channel 55 when the fuel cell stack 1 is installed. Of the pocket 70, the first side portion 710 that communicates with the outlet channel groove 25 is formed by a narrow groove 715 with a smaller cross-sectional area than the outlet channel groove 25. In this way, water accumulated in the outlet channel groove 25 can be drawn into the pocket 70 by capillary action. This prevents water generated in the fuel cell cell 100 during power generation from accumulating in the outlet channel groove 25 and blocking the outlet channel 550.
[0035] Furthermore, according to the above embodiment, it is possible to suppress the accumulation of water generated in the fuel cell cell 100 during power generation in the outlet channel groove 25, which would otherwise block the outlet channel 550. This makes it possible to eliminate the need for scavenging, reduce the number of scavenging treatments, or shorten the time required for scavenging treatment.
[0036] It is not essential that the pocket 70 has a bottom portion 730 and a second side portion 750. Having at least a first side portion 710 of the pocket 70 can prevent the outlet passage 550 from becoming blocked.
[0037] B. Other embodiments: (B1) The narrow groove 715 may have numerous fine irregularities resembling a lotus leaf across its entire surface. With this configuration, water accumulated in the outlet channel grooves 25, 35 can be drawn more reliably into the pockets 70, 80, thereby further suppressing blockage of the outlet channels 550, 650.
[0038] (B2) As shown in Figure 2, the fuel cell stack 1 may include a pocket 70 that communicates with an outlet channel groove 25 provided in the outlet connection channel section 55 of the anode channel section 50, and a pocket 80 that communicates with an outlet channel groove 35 provided in the outlet connection channel section 65 of the cathode channel section 60. With this configuration, it is possible to suppress the blockage of the outlet channels 550 and 650 on either the anode side or the cathode side. This reduces the possibility that water generated in the fuel cell cell 100 during power generation and reaction gases not used for power generation cannot be discharged from the fuel cell cell 100 to the outside of the fuel cell cell 100. Therefore, it is possible to avoid situations in which power generation by the fuel cell cell 100 cannot be continued, or in which power generation by the fuel cell cell 100 cannot be restarted after power generation has stopped.
[0039] (B3) The fuel cell stack 1 may have a pocket 80 on the cathode side instead of a pocket 70 on the anode side. In this configuration, it is possible to suppress blockage of the outlet flow path 650 on the cathode side.
[0040] (B4) The installation orientation of the fuel cell stack 1 is not limited to the installation orientation of the first embodiment. For example, as shown in Figure 7, in the fuel cell stack 1, the +X direction may be the direction of gravity and the -X direction may be the direction of anti-gravity. In this case, the entire outlet manifold 46a is positioned on the gravity side of the outlet connection flow path 55. In this case, a part of the first side portion 710a, the bottom portion 730a, and a part of the second side portion 750a of the pocket 70a may be formed by the inner wall 460a of the outlet manifold 46a. In this configuration, at least a part of the pocket 70a can be formed by the inner wall 460a of the outlet manifold 46a without shifting the position of the end portion 465a of the outlet manifold 46a in order to form the pocket 70a.
[0041] Furthermore, it is not essential that the outlet manifolds 43, 46, and 46a are positioned on the gravity side of the outlet connection flow channels 55 and 65 when the fuel cell stack 1 is installed. Also, it is not essential that at least a portion of the pockets 70, 70a, and 80 are formed by the inner walls 460 and 460a of the outlet manifolds 43, 46, and 46a.
[0042] (B5) The configuration of the fuel cell stack 1 is not limited to the above. In the fuel cell stack 1, each fuel cell cell 100 may be provided with, for example, meandering main flow channel grooves 22, 32. In other words, the main flow channels 510, 610 may be serpentine flow channels through which the reaction gas flows in a meandering manner. Even in such a configuration, it is possible to suppress the blockage of the outlet flow channels 550, 650.
[0043] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features of the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]
[0044] 1…Fuel cell stack, 10…Plate member, 10a…Anode-facing surface, 10c…Cathode-facing surface, 11…Membrane electrode gas diffusion layer assembly, 11r…Outer periphery, 12…Resin sheet, 13…Opening, 15-18…Slit, 20…Anode separator, 20c,30c…Cooling surface, 20g,30g…Gas surface, 21,31…Main body, 22,32…Main flow channel groove, 23,33…Inlet flow channel groove, 25,35…Outlet flow channel groove, 30…Cathode separator, 41…Fuel gas inlet manifold, 42…Coolant inlet manifold, 43…Oxidizer gas outlet manifold, 44…Oxidizer gas inlet manifold, 45…Coolant Outlet manifold, 46, 46a…Fuel gas outlet manifold, 50…Anode flow path section, 51, 61…Main flow path section, 53, 63…Inlet connection flow path section, 55, 65…Outlet connection flow path section, 60…Cathode flow path section, 70, 70a, 80…Pocket, 100…Fuel cell cell, 460, 460a…Inner wall, 465, 465a…End section, 510, 610…Main flow path, 530, 630…Inlet flow path, 550, 650…Outlet flow path, 555…Lower end, 710, 710a…First side section, 715…Narrow groove, 730, 730a…Bottom section, 731…One end section, 732…Other end section, 750, 750a…Second side section, DL…Stacking direction, R…Region
Claims
1. A fuel cell stack in which multiple fuel cell cells are stacked, Each of the aforementioned fuel cell cells is: A plate member having a membrane electrode gas diffusion layer assembly and a resin sheet that holds the outer periphery of the membrane electrode gas diffusion layer assembly, A separator facing the aforementioned plate member, A fluid passage section for circulating fluid between the plate member and the separator, The system includes an outlet manifold for discharging the fluid outside the fuel cell, The aforementioned flow channel section is The main channel portion facing the aforementioned membrane electrode gas diffusion layer assembly, A connecting channel section that connects the main channel section and the outlet manifold, comprising a connecting channel section facing the resin sheet, The aforementioned connecting channel section has a plurality of channel grooves that form a plurality of outlet channels, The fuel cell stack comprises a pocket that communicates with the flow channel groove and is formed by the gap between adjacent fuel cell cells, and which is positioned on the gravity side of the connecting flow channel portion in the installation orientation of the fuel cell stack. The fuel cell stack has a first side portion formed by a narrow groove that extends from the lower end of the connecting channel portion toward the direction of gravity portion in the installation position, and has a smaller cross-sectional area than the channel groove.
2. A fuel cell stack according to claim 1, The aforementioned pocket further, A bottom portion connected to the first side portion and positioned on the side of the narrow groove in the direction of gravity in the installation position, A fuel cell stack having a second side portion extending from the end of the bottom portion opposite to the end connected to the narrow groove, in the installation position, toward the anti-gravity direction relative to the bottom portion.
3. A fuel cell stack according to claim 1, At least a portion of the outlet manifold is positioned on the gravity side of the connecting flow path portion in the installation orientation. A fuel cell stack in which at least a portion of the pocket is formed by the inner wall of the outlet manifold.
4. A fuel cell stack according to claim 1, The flow path section includes an anode flow path section that allows fuel gas to flow between the plate member and the anode separator, The fuel cell stack comprises at least the pockets that communicate with the flow channel grooves provided in the connecting flow channel portion of the anode flow channel portion.
5. A fuel cell stack according to claim 1, The aforementioned fine grooves provide an uneven surface throughout the entire surface of the fuel cell stack.