fuel cells
The fuel cell's independently adjustable cross-sectional area changing devices address the challenge of water discharge and pressure loss by optimizing gas flow paths, enhancing efficiency in both water removal and airflow.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-12-19
- Publication Date
- 2026-07-01
AI Technical Summary
Existing fuel cell technologies face challenges in efficiently discharging generated water while minimizing pressure loss in the gas channel, as altering the cross-sectional area of the gas channel uniformly leads to increased pressure loss in areas with less generated water.
A fuel cell design with independently controllable cross-sectional area changing devices in the gas flow paths, allowing for localized adjustment of the cross-sectional area to promote generated water discharge and reduce pressure loss.
The design efficiently promotes the drainage of generated water and reduces pressure loss by independently adjusting the cross-sectional area of gas flow paths, optimizing water discharge and airflow.
Smart Images
Figure 2026109382000001_ABST
Abstract
Description
Technical Field
[0001] The technology disclosed in this specification relates to fuel cells.
Background Art
[0002] The fuel cell disclosed in Patent Document 1 has a structure in which a membrane electrode assembly is sandwiched between two separators. Each separator is in contact with the membrane electrode assembly. In addition, recesses are provided on the surfaces of the two separators on the side of the membrane electrode assembly, respectively. A gas flow path through which gas flows is provided in the space surrounded by the recess and the membrane electrode assembly. The fuel cell has a cross-sectional area changing device for changing the cross-sectional area of the gas flow path.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In fuel cells, electricity is generated by the reaction of hydrogen and air (i.e., oxygen) in a membrane electrode complex. During this reaction, water (hereinafter referred to as "generated water") is produced within the membrane electrode complex. This generated water is discharged from the membrane electrode complex to the outside of the fuel cell via a gas channel. When generated water is present in the gas channel, a smaller cross-sectional area of the gas channel allows for a faster gas flow, thus facilitating the discharge of the generated water. In the fuel cell described in Patent Document 1, a cross-sectional area changing device can alter the cross-sectional area of the gas channel. Therefore, reducing the cross-sectional area of the gas channel when generated water is present can promote the discharge of generated water. However, in the technology of Patent Document 1, the cross-sectional area of the gas channel is altered across the entire gas channel. Therefore, reducing the cross-sectional area of the gas channel when generated water is present results in a smaller cross-sectional area even in areas with less generated water, leading to increased pressure loss in those areas. This specification proposes a technology to promote the drainage of generated water from the gas channel of a fuel cell while simultaneously reducing pressure loss within the gas channel. [Means for solving the problem]
[0005] The fuel cell disclosed herein includes a membrane electrode complex and a separator that is in contact with the membrane electrode complex and has a first recess on its surface that is in contact with the membrane electrode complex. The fuel cell also has a first gas flow path surrounded by the first recess and the membrane electrode complex. The first gas flow path has a first portion and a second portion located downstream of the first portion. The fuel cell has a cross-sectional area changing device that changes the cross-sectional area of the flow path of the first portion and the cross-sectional area of the flow path of the second portion. The cross-sectional area changing device can change the cross-sectional area of the flow path of the first portion and the cross-sectional area of the flow path of the second portion independently.
[0006] According to the fuel cell described above, the cross-sectional area changing device can independently change the cross-sectional area of the first and second sections of the flow path. Therefore, when generated water is present in the first section, reducing the cross-sectional area of the first section promotes the discharge of the generated water, while increasing the cross-sectional area of the second section reduces pressure loss in the second section. Similarly, when generated water is present in the second section, reducing the cross-sectional area of the second section promotes the discharge of the generated water, while increasing the cross-sectional area of the first section reduces pressure loss in the first section. Thus, this fuel cell can promote the drainage of generated water from the gas flow path and reduce pressure loss within the gas flow path. [Brief explanation of the drawing]
[0007] [Figure 1] This is a plan view of a fuel cell. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is an enlarged plan view of the air-gas flow path of a fuel cell. [Figure 4] This is a side view of the air-gas flow path of a fuel cell. [Figure 5] This is a cross-sectional view of a fuel cell. [Figure 6] This is a cross-sectional view of a fuel cell. [Modes for carrying out the invention]
[0008] In the fuel cell described above, the cross-sectional area changing device may control the cross-sectional area of the flow path in the first portion to be larger than the cross-sectional area of the flow path in the second portion.
[0009] The amount of generated water tends to increase downstream of the gas flow path. With this configuration, the cross-sectional area of the second section of the flow path located downstream can be made smaller than that of the first section, thus effectively promoting the drainage of generated water.
[0010] In the fuel cell described above, the second recess may be provided in the separator. The fuel cell may also further have a second gas flow path surrounded by the second recess and the membrane electrode composite. When the first gas flow path and the second gas flow path are viewed at adjacent positions, the cross-sectional area changing device may control the cross-sectional area of the first gas flow path to be different from the cross-sectional area of the second gas flow path.
[0011] In this configuration, gas flowing through a gas channel with a small cross-sectional area flows through a membrane electrode complex to a gas channel with a larger cross-sectional area. When generated water is present in the first gas channel, making the cross-sectional area of the second gas channel smaller than that of the first gas channel allows more air to flow through the first gas channel, thus efficiently promoting the discharge of generated water. Similarly, when generated water is present in the second gas channel, making the cross-sectional area of the first gas channel smaller than that of the second gas channel allows more air to flow through the second gas channel, thus efficiently promoting the discharge of generated water.
[0012] In the fuel cell described above, a second recess extending along the first recess may be provided in the separator. The fuel cell may further have a second gas flow path surrounded by the second recess and the membrane electrode composite. The cross-sectional area changing device may control the cross-sectional area of the gas flow path with a large amount of generated water present inside the first gas flow path and the second gas flow path to be larger than the cross-sectional area of the gas flow path with a small amount of generated water present inside.
[0013] With this configuration, the amount of gas flowing through the gas channel, which contains a large amount of generated water, increases, thus promoting the drainage of the generated water within the gas channel. [Examples]
[0014] The fuel cell 100 in the embodiment shown in Figure 1 is, for example, mounted on a fuel cell vehicle that uses a fuel cell as a power source. The fuel cell 100 has a plate-shaped cell 10. Hereinafter, the thickness direction of the cell 10 will be referred to as the z direction, the direction along the surface of the cell 10 will be referred to as the x direction, and the direction along the surface of the cell 10 and perpendicular to the x direction will be referred to as the y direction. As shown in Figure 2, the cell 10 has a membrane electrode complex 12, a separator 20 and a separator 22. The membrane electrode complex 12 generates electricity by reacting hydrogen and oxygen. The membrane electrode complex 12 has a membrane electrode layer 14, a gas diffusion layer 16 and a gas diffusion layer 18. The membrane electrode layer 14, although not shown, has a structure in which an electrolyte membrane is sandwiched between two electrode layers.
[0015] The gas diffusion layers 16 and 18 are made of, for example, carbon fibers. A membrane electrode layer 14 is sandwiched between the gas diffusion layers 16 and 18. That is, one surface of the membrane electrode layer 14 is in contact with the gas diffusion layer 16, and the other surface of the membrane electrode layer 14 is in contact with the gas diffusion layer 18.
[0016] The separators 20 and 22 are made of a gas-impermeable conductive material. For example, metal materials such as stainless steel or carbon materials can be used for the separators 20 and 22. A membrane electrode composite 12 is sandwiched between separators 20 and 22. Separator 20 is in contact with the surface of the gas diffusion layer 16. Separator 22 is in contact with the surface of the gas diffusion layer 18. That is, one surface of the membrane electrode composite 12 is in contact with separator 20, and the other surface of the membrane electrode composite 12 is in contact with separator 22.
[0017] When the separator 20 is bent, a plurality of recesses 24 are provided on the surface of the separator 20 on the side of the membrane electrode assembly 12. An air gas flow path 30 is formed by the space surrounded by each recess 24 and the membrane electrode assembly 12. The plurality of air gas flow paths 30 are arranged at intervals in the y direction. Further, the plurality of air gas flow paths 30 extend along the x-axis direction. The separator 20 is provided with an air gas supply port 70 and an air gas discharge port 72. The air supplied from the air gas supply port 70 flows through each air gas flow path 30. The air that has passed through each air gas flow path 30 is discharged from the air gas discharge port 72 to the outside of the fuel cell 100. Further, the air flowing through each air gas flow path 30 is supplied to the membrane electrode layer 14 through the gas diffusion layer 16.
[0018] When the separator 22 is bent, a plurality of recesses 26 are provided on the surface of the separator 22 on the side of the membrane electrode assembly 12. A hydrogen gas flow path 40 is formed by the portion surrounded by each recess 26 and the membrane electrode assembly 12. The plurality of hydrogen gas flow paths 40 are arranged at intervals in the y direction. Further, the plurality of hydrogen gas flow paths 40 extend along the x-axis direction. The separator 22 is provided with a hydrogen gas supply port and a hydrogen gas discharge port. The hydrogen gas supplied from the hydrogen gas supply port flows through each hydrogen gas flow path 40. The hydrogen gas that has passed through each hydrogen gas flow path 40 is discharged from the hydrogen gas discharge port to the outside of the fuel cell 100. Further, the hydrogen gas flowing through each hydrogen gas flow path 40 is supplied to the membrane electrode layer 14 through the gas diffusion layer 18.
[0019] In the membrane electrode assembly 12, power is generated by reacting the air supplied from each air gas flow path 30 with the hydrogen gas supplied from each hydrogen gas flow path 40. Further, water is generated in the membrane electrode assembly 12 along with this reaction (hereinafter referred to as generated water). The generated water is discharged to the outside of the fuel cell 100 through the air gas flow path 30 by the pressure of the air flowing through the air gas flow path 30.
[0020] Next, the structure of the flow path of each air gas flow path 30 will be described. The arrows in FIGS. 3 and 4 represent the direction in which air flows.
[0021] As shown in FIG. 3, the air gas flow path 30 has portions 51, 52, 53, 54, and 55. In the direction in which air flows, the portions 51, 52, 53, 54, and 55 are arranged in this order. The portion 51 is arranged at a position closest to the air gas supply port 70. The portion 52 is arranged on the downstream side of the air gas flow path 30 with respect to the portion 51. The portion 53 is arranged on the downstream side of the air gas flow path 30 with respect to the portion 52. The portion 54 is arranged on the downstream side of the air gas flow path 30 with respect to the portion 53. The portion 55 is on the downstream side of the air gas flow path 30 with respect to the portion 54 and is arranged at a position close to the air gas discharge port 72. The air gas flow path 30 is partitioned into five regions by the portions 51 to 55.
[0022] As shown in FIG. 2, the fuel cell 100 has a cross-sectional area changing device 60. The cross-sectional area changing device 60 is provided on the bottom surface 24a of the recess 24. The cross-sectional area changing device 60 has actuators 61 to 65 provided on the bottom surface 24a of the recess 24. The actuators 61 to 65 are electrically controlled actuators. Each of the actuators 61 to 65 has a surface 66 that constitutes the wall surface of the air gas flow path 30, and reciprocates the surface 66 along the z direction. That is, the surface 66 reciprocates in a direction perpendicular to the membrane electrode assembly 12. The actuators 61 to 65 change the cross-sectional area of the flow path of the air gas flow path 30 by moving the surface 66 in the z direction. Each of the actuators 61 to 65 moves independently. That is, the cross-sectional area changing device 60 can independently change the cross-sectional area of the flow path from the portion 51 to the portion 55.
[0023] As described above, the cross-sectional area changing device 60 can independently change the cross-sectional area of each of the flow channels from section 51 to section 55. Therefore, the cross-sectional area changing device 60 can make the cross-sectional area of the flow channel in the part of the air-gas flow channel 30 where generated water has accumulated smaller than the cross-sectional area of the flow channel in the part where generated water has not accumulated. If there is more generated water accumulated downstream of the air-gas flow channel 30 than upstream, the cross-sectional area changing device 60 controls the flow channel of the air-gas flow channel 30 to decrease from section 51 to section 55, as shown in Figure 4. In other words, the cross-sectional area changing device 60 makes the cross-sectional area of the downstream flow channel smaller than the cross-sectional area of the upstream flow channel of the air-gas flow channel 30. At this time, the flow velocity downstream of the air-gas flow channel 30 is faster than the flow velocity upstream of the air-gas flow channel 30. Therefore, the generated water accumulated downstream of the air-gas flow channel 30 is easily discharged. Furthermore, since the cross-sectional area of the air-gas passage 30 on the upstream side (i.e., where no generated water has accumulated) is larger than the cross-sectional area on the downstream side of the air-gas passage 30, the pressure loss within the air-gas passage 30 is reduced. Thus, this fuel cell 100 promotes the drainage of generated water within the air-gas passage 30 and reduces the pressure loss within the air-gas passage 30.
[0024] Next, the structure within each of the adjacent air-gas passages 30a and 30b will be described. As shown in Figure 5, a cross-sectional area changing device 60 is provided in each of the adjacent air-gas passages 30a and 30b. The cross-sectional area changing device 60a for air-gas passage 30a and the cross-sectional area changing device 60b for air-gas passage 30b operate independently. Therefore, by controlling the cross-sectional area changing devices 60a and 60b, the cross-sectional area of the air-gas passage 30a and the cross-sectional area of the air-gas passage 30b can be changed to different sizes. As shown in Figure 5, when air-gas passages 30a and 30b are adjacent, the cross-sectional area of air-gas passage 30a can be made smaller than the cross-sectional area of air-gas passage 30b. This creates a pressure difference between air-gas passages 30a and 30b. Due to the pressure difference between the air-gas passages 30, air flows from air-gas passage 30a to air-gas passage 30b via the gas diffusion layer 16, as shown by arrow 90. In this way, by making the cross-sectional area of air-gas passage 30a smaller than the cross-sectional area of air-gas passage 30b at adjacent locations, the amount of air flowing through air-gas passage 30b can be increased. With this configuration, the amount of air between adjacent air-gas passages 30 can be adjusted. For example, by allowing more air to flow through the air-gas passage 30 with a large amount of generated water, the discharge of generated water can be promoted.
[0025] Furthermore, the cross-sectional area changing device 60 can adjust the amount of air flowing through the air-gas passages 30a and 30c (see Figure 6), which are located at separate positions in the y-direction. The cross-sectional area changing device 60a for air-gas passage 30a and the cross-sectional area changing device 60c for air-gas passage 30c operate independently. Therefore, by controlling the cross-sectional area changing devices 60a and 60c, the cross-sectional area of the air-gas passage 30a and the cross-sectional area of the air-gas passage 30c can be changed to different sizes. As described above, the upstream end of each air-gas passage 30 is connected to a common air-gas supply port 70. Therefore, if the cross-sectional area of air-gas passage 30a is made larger than the cross-sectional area of air-gas passage 30c, the amount of air flowing through air-gas passage 30a increases while the amount of air flowing through air-gas passage 30c decreases. With this configuration, the amount of air between air-gas passages 30 that are separated in the y-direction can be adjusted. For example, by allowing more air to flow through the air-gas passage 30 with a large amount of generated water, the discharge of generated water can be promoted.
[0026] In the embodiment described above, the cross-sectional area changing device 60 was provided in the air gas passage 30. However, the cross-sectional area changing device 60 may also be provided in the hydrogen gas passage 40.
[0027] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness. [Explanation of symbols]
[0028] 12: Membrane electrode complex 20, 22: Separator 24, 26: Recessed 30, 30a, 30b, 30c: Air gas flow path 40: Hydrogen gas flow path 51, 52, 53, 54, 55: Part 60, 60a, 60b, 60c: Cross-sectional area changing device 100: Fuel cell
Claims
1. It is a fuel cell, Membrane electrode complex, A separator that is in contact with the film electrode complex and has a first recess on its surface that is in contact with the film electrode complex, A first gas channel surrounded by the first recess and the membrane electrode composite, the first gas channel having a first portion and a second portion disposed downstream of the first portion, A cross-sectional area changing device for changing the cross-sectional area of the flow path in the first part and the cross-sectional area of the flow path in the second part. Yes, The cross-sectional area changing device is capable of independently changing the cross-sectional area of the first portion of the flow path and the cross-sectional area of the second portion of the flow path. fuel cell.
2. The fuel cell according to claim 1, wherein the cross-sectional area changing device controls the cross-sectional area of the flow path in the first portion to be larger than the cross-sectional area of the flow path in the second portion.
3. A second recess is provided in the separator, The fuel cell further comprises a second gas channel surrounded by the second recess and the membrane electrode composite, The fuel cell according to claim 1 or 2, wherein, when viewed at a position where the first gas flow path and the second gas flow path are adjacent, the cross-sectional area changing device controls the cross-sectional area of the first gas flow path to be different from the cross-sectional area of the second gas flow path.
4. A second recess is provided in the separator, The fuel cell further comprises a second gas channel surrounded by the second recess and the membrane electrode composite, The fuel cell according to claim 1 or 2, wherein the cross-sectional area changing device controls the cross-sectional area of the gas flow path with a large amount of generated water present inside the first gas flow path and the second gas flow path to be larger than the cross-sectional area of the gas flow path with a small amount of generated water present inside.