Fuel cell

Abstract

A fuel cell in which a plurality of fuel cell units are stacked and a porous body constituting a flow path for a cooling medium is arranged between the adjacent fuel cell units, wherein the porous body includes a plurality of through holes penetrating in the flowing direction of the cooling medium, and the plurality of through holes are arranged at intervals along the longitudinal direction of the porous body in a direction orthogonal to the flowing direction of the cooling medium.

Description

fuel cell

[0001] The technology disclosed in this specification relates to a fuel cell that generates electricity when supplied with fuel and oxidant.

[0002] A known example of this type of technology is the "fuel cell stack system" described in Patent Document 1 listed below. This system includes a fuel cell in which multiple fuel cell units are stacked, an anode gas flow path (fuel supply passage) that supplies fuel to the fuel cell, a cathode gas flow path (oxidant supply passage) that supplies oxidant to the fuel cell, and a porous body that is disposed between adjacent fuel cell units and forms a flow path through which a cooling medium flows. In this system, the fuel cell is cooled by flowing the cooling medium through the porous body.

[0003] Japanese Patent Application Laid-Open No. 2008-305627

[0004] However, in the fuel cell described in Patent Document 1, the fuel cell is cooled by flowing a cooling medium through a porous body, but as the fuel cell generates more heat when it reaches high output, there was a concern that the fuel cell would not be cooled sufficiently.

[0005] This disclosed technology has been made in consideration of the above circumstances, and its purpose is to provide a fuel cell that enables the porous body to increase the cooling effect of the fuel cell, thereby ensuring sufficient cooling effect even when the fuel cell has high output.

[0006] (1) In order to achieve the above-mentioned object, one aspect of the present disclosure is directed to a fuel cell in which a plurality of fuel cell cells are stacked and a porous body is disposed between adjacent fuel cell cells, forming a flow path through which a cooling medium flows, wherein the porous body has a plurality of through holes that penetrate in the direction in which the cooling medium flows.

[0007] According to this aspect, a cooling medium is passed through the porous body arranged between the fuel cells, thereby cooling each fuel cell and thereby cooling the entire fuel cell. The cooling medium is drawn up into the porous body by its capillary force. Furthermore, the cooling medium is vaporized in response to heat from the fuel cells, thereby removing heat from the fuel cells and cooling them. Furthermore, the specific surface area of ​​the porous body relative to air increases by the amount of the inner surfaces of the multiple through holes, increasing the amount of cooling medium vaporized in the porous body.

[0008] The technology described in (2) is the same as the above-mentioned (1), in which the multiple through holes are arranged at intervals along the longitudinal direction of the porous body in a direction perpendicular to the direction in which the cooling medium flows, and the intervals are different between the middle part and both ends in the longitudinal direction.

[0009] According to this aspect, the heat generation of the fuel cell disposed between the porous body may differ between the intermediate portion and both ends in the longitudinal direction. In this case, the spacing between the plurality of through holes is adjusted between the intermediate portion and both ends in the longitudinal direction. This allows the amount of evaporation of the cooling medium in the porous body to be adjusted in the longitudinal direction.

[0010] The technique described in (3) is the aspect of (2) above, in which the gap is narrowest at the middle part in the longitudinal direction.

[0011] According to this aspect, the intervals between the plurality of through holes are narrowest at the intermediate portion in the longitudinal direction, so that the amount of evaporation of the cooling medium in the porous body is greater at the intermediate portion in the longitudinal direction.

[0012] The technology described in (4) is the same as the above (1), in that the multiple through holes are arranged at intervals along the longitudinal direction of the porous body in a direction perpendicular to the direction in which the cooling medium flows, and the cross-sectional area of ​​the through holes differs between the middle part and both end parts in the longitudinal direction.

[0013] According to this aspect, the heat generation of the fuel cell disposed between the porous body may differ between the intermediate portion and both ends in the longitudinal direction. In this case, the cross-sectional area of ​​the plurality of through holes is adjusted between the intermediate portion and both ends in the longitudinal direction. This allows the amount of evaporation of the cooling medium in the porous body to be adjusted in the longitudinal direction.

[0014] The technology described in (5) is the aspect of (4) above, wherein the cross-sectional area of ​​the through-hole is largest at the middle part in the longitudinal direction.

[0015] According to this aspect, the cross-sectional area of ​​the plurality of through holes is largest in the middle portion in the longitudinal direction, so that the amount of evaporation of the cooling medium in the porous body is greater in the middle portion in the longitudinal direction.

[0016] The technology described in (6) is the same as the above-mentioned (1), in which the porous body is formed from a single material, and the porosity of the porous body differs between the middle part and both end parts in the longitudinal direction of the porous body in the direction perpendicular to the direction in which the cooling medium flows.

[0017] According to this aspect, the heat generation of the fuel cell arranged between the porous body may differ between the intermediate portion and both end portions in the longitudinal direction. In this case, the porosity of the porous body is adjusted between the intermediate portion and both end portions in the longitudinal direction. This allows the amount of evaporation of the cooling medium in the porous body to be adjusted between the intermediate portion and both end portions.

[0018] The technology described in (7) is the aspect of the above (6) in which the porosity of the porous body is highest in the middle part in the longitudinal direction.

[0019] According to this aspect, the porosity of the porous body is highest in the middle portion in the longitudinal direction, so that the amount of evaporation of the cooling medium in the porous body is greater in the middle portion.

[0020] The technology described in (8) is the same as the above-mentioned (1), in which the porous body is formed from a single material, and the porosity of the porous body differs between the middle part and both ends in the direction in which the cooling medium flows.

[0021] According to this aspect, the heat generation of the fuel cell arranged between the porous body may differ between the middle portion and both end portions in the direction of the coolant flow. In this case, the porosity of the porous body is adjusted between the middle portion and both end portions. This adjusts the amount of vaporization of the coolant in the porous body between the middle portion and both end portions.

[0022] The technology described in (9) is the aspect of the above (8) in which the porosity of the porous body is highest in the middle part in the direction in which the cooling medium flows.

[0023] According to this aspect, the porosity of the porous body is highest in the middle portion in the direction in which the cooling medium flows, so the amount of evaporation of the cooling medium in the porous body increases in the middle portion.

[0024] The technology described in (10) is an aspect described in any one of (1) to (9) above, in which the porosity of the porous body is 0 in the vicinity where the porous body contacts adjacent fuel cell cells.

[0025] According to this aspect, the porosity of the porous body is 0 in the vicinity of where it contacts the fuel cell, so the thermal resistance between the porous body and the fuel cell is reduced.

[0026] According to the technique described in (1), the cooling effect of the porous body on the fuel cell can be increased, and a sufficient cooling effect can be ensured even when the fuel cell has a high output.

[0027] According to the technique described in (2), the temperature of the fuel cell can be made uniform in the longitudinal direction.

[0028] According to the technique described in (3), the cooling effect of the fuel cell can be increased in the intermediate portion in the longitudinal direction.

[0029] According to the technique described in (4), the temperature of the fuel cell can be made uniform in the longitudinal direction.

[0030] According to the technique described in (5), the cooling effect of the fuel cell can be increased in the intermediate portion in the longitudinal direction.

[0031] According to the technique described in (6), the temperature of the fuel cell can be made uniform in the longitudinal direction.

[0032] According to the technique described in (7), the cooling effect of the fuel cell can be increased in the intermediate portion in the longitudinal direction.

[0033] According to the technique described in (8), the temperature of the fuel cell can be made uniform in the direction in which the cooling medium flows.

[0034] According to the technique described in (9), the cooling effect of the fuel cell can be increased in the middle portion in the direction in which the cooling medium flows.

[0035] According to the technique described in (10), heat is easily transferred from the fuel cell to the porous body, and the cooling effect of the fuel cell can be improved.

[0036] 6 is a schematic configuration diagram showing a fuel cell system according to the first embodiment. A schematic diagram showing a cooling system according to the first embodiment. An image diagram showing a part of the FC stack shown in FIG. 2 according to the first embodiment. A schematic diagram showing a stacked structure of fuel cell cells according to the first embodiment. A perspective view showing one porous body and a pair of fuel cell cells sandwiching it on both sides according to the first embodiment. A plan view showing one porous body and a pair of fuel cell cells sandwiching it on both sides according to the first embodiment. A cross-sectional view taken along line A-A in FIG. 6 showing one porous body and a pair of fuel cell cells sandwiching it on both sides according to the first embodiment. A plan view showing one porous body and a pair of fuel cell cells sandwiching it on both sides according to the second embodiment. A plan view showing one porous body and a pair of fuel cell cells sandwiching it on both sides according to the third embodiment. A plan view showing one porous body and a pair of fuel cell cells sandwiching it on both sides according to the fourth embodiment. A perspective view showing one porous body according to the fifth embodiment. A perspective view showing one porous body according to the sixth embodiment. 10 is a perspective view showing one porous body according to the seventh embodiment; FIG. 11 is an enlarged cross-sectional view showing an image of the contact portion between the fuel cell and the porous body according to the first embodiment; FIG. 12 is an enlarged cross-sectional view showing an image of the contact portion between the fuel cell and the porous body according to the seventh embodiment; FIG. 13 is a perspective view showing one porous body according to the eighth embodiment; FIG. 14 is an enlarged cross-sectional view showing an image of the contact portion between the fuel cell and the porous body in contact with both sides thereof according to the eighth embodiment; FIG. 15 is a perspective view showing one porous body according to the ninth embodiment; FIG. 16 is an enlarged cross-sectional view showing an image of the contact portion between the fuel cell and the porous body in contact with both sides thereof according to the ninth embodiment.

[0037] Hereinafter, an embodiment in which a fuel cell is embodied in a fuel cell system mounted on an electric vehicle will be described.

[0038] First Embodiment A first embodiment will be described in detail with reference to the drawings.

[0039] [Main Configuration of Fuel Cell System] Figure 1 shows a schematic configuration diagram of a fuel cell system 1 of this embodiment. As shown in Figure 1, the fuel cell system 1 of this embodiment includes an FC stack 11, a hydrogen system 21, an air system 22, and a cooling system 23. Figure 2 shows a schematic diagram of the cooling system 23. Figure 3 shows an image diagram of a portion of the FC stack 11 shown in Figure 2.

[0040] [About the FC stack] The FC stack 11 generates power by receiving a supply of fuel and an oxidant. In this embodiment, the fuel is hydrogen gas, and the oxidant is air. The FC stack 11 generates power by receiving a supply of hydrogen gas from a hydrogen system 21 and a supply of air from an air system 22. The power generated by the FC stack 11 is supplied to a battery and an inverter (not shown). The cooling system 23 uses cooling water to cool the FC stack 11. The FC stack 11 corresponds to an example of a "fuel cell" in the disclosed technology. The cooling water corresponds to an example of a "cooling medium" in the disclosed technology.

[0041] As shown in Figures 1 and 2, in this embodiment, the FC stack 11 is configured by stacking a plurality of fuel cell cells 13. Block-shaped porous bodies 19 that form flow paths through which cooling water flows are arranged between adjacent fuel cell cells 13. The porous bodies 19 are substances that have numerous fine gaps and pores inside. Examples of the porous bodies 19 include sponges, sponge-like materials, filters, porous ceramics, and porous metals. The porous bodies 19 have properties such as breathability and absorbency, and are used in a variety of fields.

[0042] [Hydrogen System] The hydrogen system 21 is provided on the anode side of the FC stack 11. The hydrogen system 21 includes a hydrogen supply passage 31, a hydrogen discharge passage 32, and a filling passage 33.

[0043] The hydrogen supply passage 31 is a passage for supplying hydrogen gas from a hydrogen tank 41 in which hydrogen gas is stored to the FC stack 11. The hydrogen discharge passage 32 is a passage for discharging hydrogen gas (i.e., hydrogen off-gas) discharged from the FC stack 11.

[0044] The hydrogen supply passage 31 is provided with a hydrogen tank 41, a hydrogen valve 51, a hydrogen pressure reducing valve 52, and an injector 53. The filling passage 33 is a passage for filling the hydrogen tank 41 with hydrogen gas from a filling port .

[0045] The hydrogen valve 51 is a valve that switches between supplying and blocking hydrogen gas from the hydrogen tank 41 to the hydrogen supply passage 31, and is composed of multiple devices including, for example, a solenoid valve. The hydrogen pressure reducing valve 52 is a pressure adjustment valve for reducing the pressure of hydrogen gas, and is composed of, for example, a solenoid valve. The injector 53 is a device that injects hydrogen gas guided from the hydrogen tank 41 downstream, and is composed of, for example, a solenoid valve. The injector 53 is configured to adjust the discharge pressure of the hydrogen gas (hydrogen pressure) by, for example, adjusting the opening of an injection port by moving a needle valve.

[0046] An exhaust drain valve 57 is provided in the hydrogen discharge passage 32. The exhaust drain valve 57 is a valve that switches between discharging and blocking the hydrogen off-gas and moisture from the FC stack 11, and is configured by, for example, a solenoid valve.

[0047] [Air System] The air system 22 is provided on the cathode side of the FC stack 11. The air system 22 includes an air supply passage 61, an air discharge passage 62, and an air compressor 71.

[0048] The air supply passage 61 is a passage for supplying air from outside the fuel cell system 1 to the FC stack 11. The air discharge passage 62 is a passage for discharging air (i.e., air off-gas) discharged from the FC stack 11.

[0049] The air compressor 71 is an electrically operated device that supplies air to the FC stack 11. In this embodiment, no devices such as air valves are provided in the air supply passage 61 between the air compressor 71 and the FC stack 11, and in the air discharge passage 62 downstream of the FC stack 11. In other words, the FC stack 11 in this embodiment is configured so that air is directly supplied from the air compressor 71 and air off-gas is directly discharged from the FC stack 11 to the outside.

[0050] 1 and 2, the cooling system 23 includes a cooling water circulation flow path 81 that circulates cooling water through each porous body 19. A heat exchanger 82 and a water tank 83 are provided in the cooling water circulation flow path 81.

[0051] The heat exchanger 82 is disposed on the cooling water circulation flow path 81 downstream of the FC stack 11. In this embodiment, the heat exchanger 82 is configured so that the cooling water flowing through the cooling water circulation flow path 81 can exchange heat with the hydrogen gas flowing through the hydrogen supply passage 31.

[0052] The water tank 83 is disposed on the cooling water circulation flow path 81, upstream of the FC stack 11. The water tank 83 is configured to store cooling water that has been heat exchanged (cooled) in the heat exchanger 82 and liquefied (condensed).

[0053] The FC stack 11 is provided with an inlet shroud 85 on the inlet side of the cooling water, and an outlet shroud 86 on the outlet side of the cooling water. The inlet shroud 85 covers the inlet side of the FC stack 11 to allow cooling water to flow into each of the inlet sides of the multiple porous bodies 19. The downstream end of the cooling water circulation channel 81 is connected to an inlet 85a of the inlet shroud 85. The outlet shroud 86 covers the outlet side of the FC stack 11 to collect cooling water (water vapor) flowing out from the outlet sides of the multiple porous bodies 19. The upstream end of the cooling water circulation channel 81 is connected to an outlet 86a of the outlet shroud 86. The cooling water circulation channel 81 is configured as a closed loop in which only cooling water circulates. In other words, the cooling water circulation channel 81 is a closed channel that does not communicate with the outside.

[0054] As shown in Fig. 2, cooling water flows through the central tube 82a of the heat exchanger 82. Hydrogen gas supplied to the FC stack 11 flows around this central tube 82a. Hydrogen gas at about 20°C flows into the heat exchanger 82. Cooling water at about 60°C flows into the central tube 82a. The hydrogen gas is heated to about 55°C in the heat exchanger 82 and supplied to the FC stack 11. The cooling water is cooled from 60°C to about 52°C and flows into the water tank 83. The cooling water flowing from the water tank 83 to the FC stack 11 is drawn into the porous body 19 by the capillary force of the porous body 19.

[0055] As shown in Figure 3, one fuel cell 13 is composed of an electrode material 14, which serves as a heat source, and a pair of separators 15 that sandwich the electrode material 14. Cooling water is drawn into the porous body 19 from its inlet side (lower side in Figure 3) due to the capillary force of the porous body 19. At this time, heat generated by the electrode material 14 is transferred to the porous body 19 via the separator 15, causing the cooling water in the porous body 19 to transform into steam, which evaporates and dissipates heat from the outlet side (upper side in Figure 3). The latent heat of vaporization of the porous body 19 at this time cools the fuel cell 13. The heat transfer coefficient of latent heat of vaporization is overwhelmingly higher than that of air cooling or water cooling.

[0056] [Configuration of fuel cell] Figure 4 is a schematic diagram showing the stack structure of a fuel cell 13 of this embodiment. The fuel cell 13 includes an electrode material 14 and a pair of separators 15 sandwiching the electrode material 14. The electrode material 14 includes a pair of gas diffusion layers 16 in contact with each separator 15, a catalyst layer 17 in contact with each gas diffusion layer 16, and an electrolyte membrane 18 sandwiched between the pair of catalyst layers 17.

[0057] [Configuration of the porous body] Fig. 5 shows a perspective view of one porous body 19 and a pair of fuel cell cells 13 sandwiching it on both sides. Fig. 6 shows a plan view of one porous body 19 and a pair of fuel cell cells 13 sandwiching it on both sides. Fig. 7 shows a cross-sectional view of one porous body 19 and a pair of fuel cell cells 13 sandwiching it on both sides, taken along line A-A in Fig. 6. Here, for convenience, the number of through holes 20 in Fig. 5 differs by one from the number of through holes 20 in Fig. 6.

[0058] 5 to 7, the porous body 19 has a plurality of through holes 20 that penetrate in the direction Y of the cooling water flow. In this embodiment, the flow path cross section of each through hole 20 is rectangular. The flow path cross section shape of the through hole 20 may be a polygon other than a rectangle or may be circular.

[0059] Here, the multiple through holes 20 are arranged at intervals IV (see FIG. 6 ) along the longitudinal direction X of the porous body 19 (which is also the arrangement direction of the through holes 20), which is perpendicular to the direction Y in which the cooling water flows. In this embodiment, the multiple through holes 20 are arranged in a line at the center of the lateral direction Z of the porous body 19, which is perpendicular to the direction Y in which the cooling water flows. Furthermore, in this embodiment, the multiple through holes 20 are arranged at equal intervals IV.

[0060] [Operation of the fuel cell system] In the fuel cell system 1 configured as described above, hydrogen gas supplied from the hydrogen supply passage 31 to the FC stack 11 is used for power generation in the FC stack 11, and then discharged from the FC stack 11 as hydrogen off-gas via the hydrogen discharge passage 32 to the outside of the fuel cell system 1. In addition, air supplied from the air supply passage 61 to the FC stack 11 is used for power generation in the FC stack 11, and then discharged from the FC stack 11 as air off-gas via the air discharge passage 62 to the outside of the fuel cell system 1.

[0061] The electric power generated by the FC stack 11 is supplied to a battery to charge the battery, or is supplied to an inverter to drive the inverter. The inverter is also supplied with electric power from the battery.

[0062] [Operations and Effects of the Fuel Cell System] According to the configuration of the fuel cell system 1 of this embodiment described above, the FC stack 11 is cooled by circulating the cooling water through the porous body 19 by the cooling water circulation channel 81. In the cooling water circulation channel 81, the cooling water is cooled by heat exchange with hydrogen gas. The cooling water circulation channel 81 is configured as a closed loop in which only the cooling water circulates, and therefore the cooling water is not released to the outside. Therefore, the cooling water can be used efficiently to cool the FC stack 11 while reducing the consumption of cooling water.

[0063] According to the configuration of this embodiment, the air system 22 includes an air compressor 71, and air is directly supplied to the FC stack 11 from the air compressor 71, and air off-gas is directly discharged from the FC stack 11. Therefore, no air valves or the like other than the air compressor 71 are provided on the supply side of the air system 22, and no air valves or the like are provided on the discharge side of the air system 22. This allows the air system 22 to be simplified, and the cost of the fuel cell system 1 can be reduced.

[0064] [Operations and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, cooling water is passed through the porous body 19 arranged between the plurality of fuel cell cells 13, thereby cooling each of the fuel cell cells 13 and thereby cooling the entire FC stack 11. The cooling water is drawn up into the porous body 19 by its capillary force. The cooling water is also vaporized in the porous body 19 upon receiving heat from the FC stack 11, thereby removing heat from the fuel cell cells 13 and cooling them. Furthermore, the specific surface area of ​​the porous body 19 relative to air is increased by the inner surfaces of the plurality of through holes 20, thereby increasing the amount of cooling water vaporized in the porous body 19. This increases the cooling effect of the porous body 19 on the fuel cell cells 13, ensuring sufficient cooling even when the FC stack 11 operates at high output.

[0065] Second Embodiment Next, a second embodiment will be described in detail with reference to the drawings. In the following description, components equivalent to those in the first embodiment will be denoted by the same reference numerals, and differences will be mainly described.

[0066] [Configuration of the Porous Body] This embodiment differs from the first embodiment in the configuration of the porous body 19. FIG. 8 shows a plan view of one porous body 19 and a pair of fuel cell cells 13 sandwiching the porous body 19 on both sides according to this embodiment. The plurality of through holes 20 are arranged at intervals IV along the longitudinal direction X, which is perpendicular to the direction Y of the cooling water flow. In this embodiment, the through holes 20 are arranged in two rows, one at each end of the lateral direction Z of the porous body 19 (at positions in contact with the fuel cell cells 13), which is perpendicular to the direction Y of the cooling water flow. Furthermore, the cross-sectional area of ​​the through holes 20 is smaller than that of the first embodiment, but the number of through holes 20 is greater than that of the first embodiment. In this embodiment, the plurality of through holes 20 are also arranged at equal intervals IV.

[0067] [Regarding the Functions and Effects of the FC Stack] The configuration of the FC stack 11 of this embodiment can provide functions and effects equivalent to those of Embodiment 1. Furthermore, in this embodiment, the multiple through holes 20 are arranged in positions that contact the fuel cell 13, making it easier to release heat from the fuel cell 13 through the through holes 20.

[0068] Third Embodiment Next, a third embodiment will be described in detail with reference to the drawings.

[0069] [Regarding the configuration of the porous body] This embodiment differs from the above-described embodiments in terms of the configuration of the porous body 19. Fig. 9 shows a plan view of one porous body 19 and a pair of fuel cell units 13 sandwiching it on both sides according to this embodiment. In this embodiment, unlike the first embodiment, the interval IV between the plurality of through holes 20 arranged in a row in the longitudinal direction X varies between the middle portion and both end portions in the longitudinal direction X. In particular, in this embodiment, the interval IV is narrowest in the middle portion in the longitudinal direction X and is wider at both end portions in the longitudinal direction X than the middle portion. This arrangement is intended to accommodate a case in which the temperature distribution of the fuel cell unit 13 is higher in the center portion of the fuel cell unit 13.

[0070] [Regarding the Functions and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, the heat generation of the fuel cell 13 between which the porous body 19 is disposed may differ between the middle and both end portions in the longitudinal direction X. In this case, the interval IV between the multiple through holes 20 is adjusted between the middle and both end portions in the longitudinal direction X. This adjusts the amount of evaporation of the cooling water in the porous body 19 in the longitudinal direction X. Therefore, the temperature of the fuel cell 13 can be made uniform in the longitudinal direction X.

[0071] According to the configuration of this embodiment, the interval IV between the plurality of through holes 20 is narrowest in the middle portion in the longitudinal direction X, so the amount of evaporation of the cooling water in the porous body 19 is greater in the middle portion in the longitudinal direction X. Therefore, the cooling effect of the fuel cell 13 can be improved in the middle portion in the longitudinal direction X.

[0072] Fourth Embodiment Next, a fourth embodiment will be described in detail with reference to the drawings.

[0073] [Regarding the configuration of the porous body] This embodiment differs from the above-described embodiments in terms of the configuration of the porous body 19. Fig. 10 shows a plan view of one porous body 19 and a pair of fuel cell units 13 sandwiching it on both sides according to this embodiment. In this embodiment, unlike the first embodiment, the cross-sectional area of ​​the plurality of through holes 20 differs between the middle portion and both end portions in the longitudinal direction X. In particular, in this embodiment, the cross-sectional area of ​​the hole is largest in the middle portion in the longitudinal direction X and smallest at both end portions in the longitudinal direction X. This arrangement is intended to accommodate a case in which the temperature distribution of the fuel cell unit 13 is higher in the center portion of the fuel cell unit 13.

[0074] [Regarding the Functions and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, the heat generation of the fuel cell 13 between which the porous body 19 is disposed may differ between the middle portion and both ends in the longitudinal direction X. In this case, the cross-sectional area of ​​the plurality of through holes 20 is adjusted between the middle portion and both ends in the longitudinal direction X. This adjusts the amount of evaporation of the cooling water in the porous body 19 in the longitudinal direction X. Therefore, the temperature of the fuel cell 13 can be made uniform in the longitudinal direction X.

[0075] According to the configuration of this embodiment, the cross-sectional area of ​​the plurality of through holes 20 is largest in the middle portion in the longitudinal direction X, so the amount of evaporation of the cooling water in the porous body 19 is greater in the middle portion in the longitudinal direction X. Therefore, the cooling effect of the fuel cell 13 can be improved in the middle portion in the longitudinal direction X.

[0076] Fifth Embodiment Next, a fifth embodiment will be described in detail with reference to the drawings.

[0077] [Configuration of the Porous Body] This embodiment differs from the first embodiment in the configuration of the porous body 19. Fig. 11 shows a perspective view of one porous body 19 according to this embodiment. In this embodiment, similar to the first embodiment, the porous body 19 has a plurality of through holes 20 arranged in a line in the longitudinal direction X. The plurality of through holes 20 are arranged at equal intervals IV.

[0078] In this embodiment, the porous body 19 is made of a single material, but has different porosities in different parts. That is, the porosity of the porous body 19 differs between a middle portion 19a (indicated by dense dots) and both end portions 19b, 19c (indicated by coarse dots) in the longitudinal direction X. In particular, in this embodiment, the porosity of the porous body 19 is highest in the middle portion 19a, and lower at both end portions 19b, 19c than in the middle portion 19a. Here, "porosity" refers to the ratio of the volume of pores per volume of the porous body 19.

[0079] [Regarding the Functions and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, the heat generation of the fuel cell 13 between which the porous body 19 is disposed may differ between the middle portion and both end portions in the longitudinal direction X. In this case, the porosity of the porous body 19 is adjusted between the middle portion and both end portions in the longitudinal direction X. This adjusts the amount of evaporation of the cooling water in the porous body 19 between the middle portion and both end portions. Therefore, the temperature of the fuel cell 13 can be made uniform in the longitudinal direction X.

[0080] According to the configuration of this embodiment, the porosity of the porous body 19 is highest in the middle portion in the longitudinal direction X, so the amount of evaporation of the cooling water in the porous body 19 is greater in the middle portion, thereby making it possible to enhance the cooling effect of the fuel cell in the middle portion in the longitudinal direction X.

[0081] Sixth Embodiment Next, a sixth embodiment will be described in detail with reference to the drawings.

[0082] [Configuration of Porous Body] This embodiment differs from the fifth embodiment in the configuration of the porous body 19. As shown in Fig. 12, this embodiment has a plurality of through holes 20 arranged in a line in the longitudinal direction X in the porous body 19, similar to the fifth embodiment. The plurality of through holes 20 are arranged at equal intervals IV.

[0083] In this embodiment, the porous body 19 is also made of a single material, but the porosity varies depending on the portion. That is, unlike the fifth embodiment, the porosity of the porous body 19 varies between a middle portion 19d (indicated by dense dots) and both end portions 19e, 19f (indicated by coarse dots) in the cooling water flow direction Y. In particular, in this embodiment, the porosity of the porous body 19 is highest in the middle portion 19d and lower at both end portions 19e, 19f than in the middle portion 19d.

[0084] [Regarding the Functions and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, the heat generation of the fuel cell 13 between which the porous body 19 is disposed may differ between the middle portion and both ends in the direction Y in which the cooling water flows. In this case, the porosity of the porous body 19 is adjusted between the middle portion and both ends. This adjusts the amount of evaporation of the cooling water in the porous body 19 between the middle portion and both ends. Therefore, the temperature of the fuel cell 13 can be made uniform in the direction Y in which the cooling water flows.

[0085] According to the configuration of this embodiment, the porosity of the porous body 19 is highest in the middle portion in the direction Y in which the cooling water flows, and therefore the amount of evaporation of the cooling water in the porous body 19 is greater in the middle portion. Therefore, the cooling effect of the fuel cell 13 can be improved in the middle portion in the direction Y in which the cooling water flows.

[0086] Seventh Embodiment Next, a seventh embodiment will be described in detail with reference to the drawings.

[0087] [Configuration of the Porous Body] This embodiment differs from the previous embodiments in the configuration of the porous body 19. Fig. 13 shows a perspective view of one porous body 19 according to this embodiment. In this embodiment, similar to the first embodiment, the porous body 19 has a plurality of through holes 20 arranged in a line in the longitudinal direction X. The plurality of through holes 20 are arranged at equal intervals IV.

[0088] In this embodiment, the porosity of the porous body 19 is zero in the vicinity where the porous body 19 contacts adjacent fuel cell cells 13. That is, as shown in Fig. 13, the porous body 19 is formed from a single material, but the porosity of the porous body 19 differs between a middle portion 19g (indicated by dense dots) and both end portions 19h, 19i (indicated by coarse dots) in the short direction Z. In particular, in this embodiment, the porosity of the porous body 19 is "0" at both end portions 19h, 19i, and the middle portion 19g has a certain degree of porosity.

[0089] Fig. 14 relates to the first embodiment and shows an image of the contact portion between the fuel cell 13 and the porous body 19 in an enlarged cross-sectional view. Fig. 15 relates to the present embodiment and shows an image of the contact portion between the fuel cell 13 and the porous body 19 in an enlarged cross-sectional view. As shown in Fig. 14, in the first embodiment, there is a gap at the contact portion between the fuel cell 13 and the porous body 19, resulting in poor contact. As a result, thermal resistance occurs between the fuel cell 13 and the porous body 19.

[0090] 15 , in this embodiment, there are no gaps in the contact area between the fuel cell 13 and the porous body 19, improving the contact condition. That is, the porous body 19 in this embodiment is in close contact with the fuel cell 13 at the end 19h where the porosity is "0". This reduces the thermal resistance between the fuel cell 13 and the porous body 19.

[0091] [Regarding the Functions and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, the porosity of the porous body 19 is zero near the area where the porous body 19 contacts the fuel cell 13, thereby reducing the thermal resistance between the porous body 19 and the fuel cell 13. This makes it easier for heat to be transferred from the fuel cell 13 to the porous body 19, thereby improving the cooling effect of the fuel cell 13.

[0092] In this embodiment, in a configuration similar to that of the first embodiment, the porosity of the porous body 19 is set to 0 near the contact point with the fuel cell 13, but a similar configuration may be added to the configurations of the second to sixth embodiments.

[0093] Eighth Embodiment Next, an eighth embodiment will be described in detail with reference to the drawings.

[0094] [Configuration of the porous body] This embodiment differs from the seventh embodiment in the configuration of the porous body 19. Fig. 16 is a perspective view of one porous body 19 according to this embodiment. As shown in Fig. 16, the porous body 19 of this embodiment has a configuration generally equivalent to that of the seventh embodiment.

[0095] FIG. 17 is an enlarged cross-sectional view showing an image of the contact portion between the fuel cell 13 and the porous body 19 contacting both sides thereof according to this embodiment. In this embodiment, the porosity of the porous body 19 is zero near where the porous body 19 contacts the adjacent fuel cell 13. That is, as shown in FIG. 17, the end 19h of the porous body 19 contacting the right side of the fuel cell 13 includes a portion 19ha where the porosity is "0" and a portion 19hb where the porosity is not "0" and is not in contact with the fuel cell 13. This portion with a porosity that is not "0" (slightly greater than 0) constitutes the "gas flow path." Similarly, the end 19i of the porous body 19 contacting the left side of the fuel cell 13 includes a portion 19ia where the porosity is "0" and a portion 19ib where the porosity is not "0" (slightly greater than 0) and is not in contact with the fuel cell 13. This portion with a porosity that is not "0" constitutes the "gas flow path."

[0096] [Regarding the Functions and Effects of the FC Stack] The configuration of the FC stack 11 of this embodiment provides the same functions and effects as those of the seventh embodiment. Additionally, in this embodiment, the ends 19h, 19i of the porous body 19 include portions 19ha, 19ia that contact the fuel cell 13 and have a porosity of "0," and portions 19hb, 19ib that do not contact the fuel cell 13 and have a porosity of non-zero (slightly greater than 0). The non-zero porosity portions form "gas flow paths." In other words, the portions 19ha, 19ia with a porosity of "0" can function as separators for the fuel cell 13. Therefore, as shown in FIG. 17 , a separator can be omitted from the contact portion between the porous body 19 and the fuel cell 13. As a result, the number of parts of the fuel cell 13 can be reduced.

[0097] Ninth Embodiment (First Embodiment) Next, a ninth embodiment will be described in detail with reference to the drawings.

[0098] [Configuration of Porous Body] This embodiment differs from the seventh embodiment in the configuration of the porous body 19. Fig. 18 is a perspective view of one porous body 19 according to this embodiment.

[0099] As shown in Figure 18, the porous body 19 of this embodiment differs from the seventh embodiment in that an end portion 19j having pores is formed outside an end portion 19h having no pores in the short direction Z of the porous body 19, and an end portion 19k having pores is formed outside an end portion 19i having no pores.

[0100] 19 is an enlarged cross-sectional view showing an image of the contact portion between the fuel cell 13 and the porous body 19 that contacts both sides of the fuel cell 13 according to this embodiment. In this embodiment, the outermost ends 19j and 19k of the porous body 19 each contact the adjacent fuel cell 13, and therefore the outermost ends 19j and 19k that have pores function as gas diffusion layers for the fuel cell 13. Furthermore, the outermost ends 19h and 19i that follow the outermost ends 19j and 19k do not have pores, and therefore these ends 19h and 19i function as separators for the fuel cell 13.

[0101] [Regarding the Functions and Effects of the FC Stack] According to the configuration of the FC stack 11 of this embodiment, unlike the eighth embodiment, the end portions 19h and 19i without pores can function as separators, and the end portions 19j and 19k with pores can function as gas diffusion layers. Therefore, as shown in Figure 19, separators and gas diffusion layers can be omitted from the fuel cell 13. As a result, the number of parts in the fuel cell 13 can be reduced.

[0102] In this embodiment, in a configuration similar to that of the first embodiment, the porous body 19 is configured as described above near the contact portion with the fuel cell 13, but a similar configuration may be added to the configurations of the second to sixth embodiments.

[0103] <Other Embodiments> The disclosed technology is not limited to the above-described embodiments, and can be implemented by appropriately modifying part of the configuration within the scope of the disclosed technology.

[0104] (1) In each of the above embodiments, the plurality of through holes 20 are arranged in a row along the longitudinal direction X of the porous body 19. However, the through holes 20 may also be arranged in a staggered manner or randomly along the longitudinal direction X.

[0105] (2) In each of the above embodiments, the fuel cell system 1 is mounted on an electric vehicle. However, the fuel cell system may also be embodied in devices other than electric vehicles.

[0106] The disclosed technology can be used, for example, in a fuel cell system mounted on an electric vehicle.

[0107] REFERENCE SIGNS LIST 1 fuel cell system 11 FC stack (fuel cell) 13 fuel cell cell 20 through-hole Y cooling water flow direction X longitudinal direction Z lateral direction IV spacing

Claims

1. A fuel cell in which a plurality of fuel cell units are stacked and a porous body that forms a flow path through which a cooling medium flows is disposed between adjacent fuel cell units, wherein the porous body has a plurality of through holes that penetrate in the direction in which the cooling medium flows.

2. A fuel cell according to claim 1, wherein the plurality of through holes are arranged at intervals along the longitudinal direction of the porous body in a direction perpendicular to the direction in which the cooling medium flows, and the intervals vary between the middle and both ends in the longitudinal direction.

3. A fuel cell according to claim 2, wherein the gap is narrowest at the middle portion in the longitudinal direction.

4. A fuel cell according to claim 1, wherein the plurality of through holes are spaced apart along the longitudinal direction of the porous body in a direction perpendicular to the direction in which the cooling medium flows, and the cross-sectional area of ​​the through holes differs between the middle and both ends in the longitudinal direction.

5. A fuel cell according to claim 4, wherein the cross-sectional area of ​​the through-hole is largest at the middle portion in the longitudinal direction.

6. A fuel cell according to claim 1, wherein the porous body is formed from a single material, and the porosity of the porous body varies between the middle and both ends of the porous body in the longitudinal direction perpendicular to the direction in which the cooling medium flows.

7. A fuel cell according to claim 6, wherein the porosity of said porous body is highest at the middle part in the longitudinal direction.

8. A fuel cell according to claim 1, wherein the porous body is formed from a single material, and the porosity of the porous body differs between the middle portion and both ends in the direction in which the cooling medium flows.

9. A fuel cell according to claim 8, wherein the porosity of the porous body is highest at the middle portion in the direction in which the cooling medium flows.

10. A fuel cell according to any one of claims 1 to 9, characterized in that the porosity of the porous body is 0 in the vicinity where the porous body contacts the adjacent fuel cell.

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