Fuel cell system

Abstract

To efficiently use the cooling medium to cool the fuel cell while minimizing its consumption. [Solution] The fuel cell system 1 comprises an FC stack 11 in which a plurality of fuel cell cells 13 are stacked, a hydrogen supply passage 31 for supplying hydrogen gas to the FC stack 11, an air supply passage 61 for supplying air to the FC stack 11, a porous body 18 arranged between adjacent fuel cell cells 13 and constituting a flow path through which cooling water flows, and a cooling water circulation passage 81 for circulating cooling water through the porous body 18. The cooling water circulation passage 81 is configured so that the cooling water can exchange heat with at least one of hydrogen gas and air, and is configured as a closed loop through which only cooling water circulates. A heat exchanger 82 capable of exchanging heat between the cooling water and hydrogen gas is arranged in the cooling water circulation passage 81. A first fan 88 is provided in the heat exchanger 82 for blowing air toward the heat exchanger 82.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fuel cell system including a fuel cell that generates electricity by receiving supplies of fuel and an oxidant.

Background Art

[0002] Conventionally, as this type of technology, for example, a "fuel cell stack system" described in Patent Document 1 below is known. This system includes a fuel cell in which a plurality of fuel cells 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 an oxidant to the fuel cell, and a porous body that is disposed between adjacent fuel cells and constitutes a flow path through which a cooling medium flows. In this system, the cooling medium that flows through the porous body and vaporizes is used for humidifying the oxidant.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the system described in Patent Document 1, the fuel cell can be cooled by flowing a cooling medium through the porous body between the fuel cells. However, the cooling medium that has flowed through the porous body is also used for humidifying the oxidant and is consumed. Therefore, when the cooling medium is consumed, it becomes difficult to obtain sufficient cooling performance, and it is necessary to periodically replenish the cooling medium. Further, regarding the cooling of the fuel cell, the degree of cooling (cooling amount) is determined by the flow rate of the fuel used in the reaction. Therefore, simply flowing the cooling medium through the porous body has a problem in terms of controllability of the cooling amount.

[0005] This disclosed technology has been made in view of the above circumstances, and its purpose is to provide a fuel cell system that enables efficient use of the cooling medium for cooling the fuel cell while suppressing the consumption of the cooling medium. [Means for solving the problem]

[0006] To achieve the above objective, the technology described in claim 1 provides a fuel cell system comprising a fuel cell in which a plurality of fuel cell cells are stacked, a fuel supply passage for supplying fuel to the fuel cell, an oxidizer supply passage for supplying an oxidizer to the fuel cell, and a porous body disposed between adjacent fuel cell cells and constituting a flow path for a cooling medium, wherein the system further comprises a cooling medium circulation flow path for circulating the cooling medium through the porous body, and the cooling medium circulation flow path is configured such that the cooling medium can exchange heat with at least one of the fuel and the oxidizer, and is configured as a closed loop through which only the cooling medium circulates.

[0007] According to the above technology configuration, each fuel cell is cooled by circulating a cooling medium through a cooling medium circulation channel in a porous body placed between multiple fuel cell cells, thereby cooling the entire fuel cell. In this configuration, the cooling medium is drawn up by the capillary force of the porous body. In addition, the cooling medium vaporizes in the porous body upon receiving heat from the fuel cell cells, thereby removing heat from the fuel cell cells and cooling them. Furthermore, in the cooling medium circulation channel, the cooling medium is cooled by heat exchange with at least one of the fuel and oxidizer, and then returned to the fuel cell. Moreover, since the cooling medium circulation channel is a closed loop in which only the cooling medium circulates, the cooling medium is not released to the outside.

[0008] To achieve the above objective, the technology described in claim 2 is characterized in that, in the technology described in claim 1, a heat exchanger is arranged in a cooling medium circulation channel and configured so that the cooling medium can exchange heat with the fuel, and a first fan blows air toward the heat exchanger in order to cool the heat exchanger.

[0009] According to the configuration of the above technology, in addition to the operation of the technology described in claim 1, in the cooling medium circulation channel, the cooling medium is cooled by heat exchange with the fuel by the heat exchanger. Furthermore, since the heat exchanger is cooled by the airflow from the first fan, the cooling of the cooling medium in the heat exchanger is promoted.

[0010] To achieve the above objective, the technology described in claim 3 further comprises, in the technology described in claim 2, a temperature sensor for measuring the temperature of the fuel cell and a first control unit for controlling the first fan, wherein the first control unit controls the first fan so that the amount of air blown corresponds to the measurement value of the temperature sensor.

[0011] According to the configuration of the above technology, in addition to the operation of the technology described in claim 2, the first control unit controls the first fan so that the amount of air blown corresponds to the temperature of the fuel cell measured by the temperature sensor. Therefore, the amount of cooling of the fuel cell is adjusted according to the temperature of the fuel cell.

[0012] To achieve the above objective, the technology described in claim 4 is characterized in that, in the technology described in claim 1, it further comprises a heat exchanger arranged in a cooling medium circulation channel and configured so that the cooling medium can exchange heat with the fuel; an oxidant bypass passage that returns the oxidant from the oxidant supply passage to the heat exchanger, bypassing the fuel cell, and to the oxidant supply passage; and a valve device that opens and closes the connection between the oxidant supply passage and the oxidant bypass passage, and also opens and closes the oxidant bypass passage to a variable degree.

[0013] According to the configuration of the above technology, in addition to the operation of the technology described in claim 1, in the cooling medium circulation channel, the cooling medium is cooled by heat exchange with the fuel by the heat exchanger. Furthermore, by opening and closing the valve device to a variable degree, the oxidizer that has bypassed the fuel cell passes through the heat exchanger via the oxidizer bypass passage and returns to the oxidizer supply passage. This promotes the cooling of the cooling medium in the heat exchanger.

[0014] To achieve the above objective, the technology described in claim 5 is the technology described in claim 4, further comprising a temperature sensor for measuring the temperature of the fuel cell and a second control unit for controlling the valve device, wherein the second control unit controls the valve device so that the flow rate of the oxidizer through the oxidizer bypass passage corresponds to the measurement value of the temperature sensor.

[0015] According to the configuration of the above technology, in addition to the operation of the technology described in claim 4, the second control unit controls the valve device so that the flow rate of the oxidizer through the oxidizer bypass passage corresponds to the temperature of the fuel cell measured by the temperature sensor. Therefore, the amount of cooling for the fuel cell is adjusted according to the temperature of the fuel cell.

[0016] To achieve the above objective, the technology described in claim 6 is characterized in that, in the technology described in claim 1, a heat exchanger is arranged in the cooling medium circulation channel and configured so that the cooling medium can exchange heat with the fuel, and a second fan is arranged in the cooling medium circulation channel between the outlet side of the porous body and the heat exchanger to provide flow to the cooling medium.

[0017] According to the configuration of the above technology, in addition to the operation of the technology described in claim 1, in the cooling medium circulation channel, the cooling medium is cooled by heat exchange with the fuel by the heat exchanger. Furthermore, since flow is provided to the cooling medium by the second fan in the cooling medium circulation channel from the outlet side of the porous body to the heat exchanger, the cooling of the cooling medium in the heat exchanger is promoted.

[0018] To achieve the above objective, the technology described in claim 7 further comprises, in the technology described in claim 6, a temperature sensor for measuring the temperature of the fuel cell and a third control unit for controlling the second fan, wherein the third control unit controls the second fan so that the flow of the cooling medium supplied by the second fan becomes a flow velocity corresponding to the measurement value of the temperature sensor.

[0019] According to the configuration of the above technology, in addition to the operation of the technology described in claim 6, the third control unit controls the second fan so that the flow rate of the cooling medium applied by the second fan becomes a flow rate corresponding to the temperature of the fuel cell measured by the temperature sensor. Therefore, the cooling amount of the fuel cell is adjusted according to the temperature of the fuel cell.

Advantages of the Invention

[0020] According to the technology described in claim 1, the cooling medium can be efficiently used for cooling the fuel cell while suppressing the consumption of the cooling medium.

[0021] According to the technology described in claim 2, in addition to the effect of the technology described in claim 1, the cooling efficiency of the fuel cell by the cooling medium can be improved.

[0022] According to the technology described in claim 3, in addition to the effect of the technology described in claim 2, the controllability of the cooling amount of the fuel cell can be improved.

[0023] According to the technology described in claim 4, in addition to the effect of the technology described in claim 1, the cooling efficiency of the fuel cell by the cooling medium can be improved.

[0024] According to the technology described in claim 5, in addition to the effect of the technology described in claim 4, the controllability of the cooling amount of the fuel cell can be improved.

[0025] According to the technology described in claim 6, in addition to the effect of the technology described in claim 1, the cooling efficiency of the fuel cell by the cooling medium can be improved.

[0026] According to the technology described in claim 7, in addition to the effect of the technology described in claim 6, the controllability of the cooling amount of the fuel cell can be improved.

Brief Description of the Drawings

[0027] [Figure 1] A schematic configuration diagram showing a fuel cell system according to the first embodiment. [Figure 2]A schematic diagram showing the cooling system according to the first embodiment. [Figure 3] This is an illustrative diagram showing a part of the FC stack shown in Figure 2, relating to the first embodiment. [Figure 4] A schematic diagram showing a fuel cell system according to the second embodiment. [Figure 5] A schematic diagram showing a fuel cell system according to the third embodiment. [Figure 6] A schematic diagram showing a fuel cell system according to the fourth embodiment. [Modes for carrying out the invention]

[0028] The following describes an embodiment of the fuel cell system as a fuel cell system installed in an electric vehicle.

[0029] <First Embodiment> The first embodiment will be described in detail with reference to the drawings.

[0030] [Regarding the main components of a fuel cell system] Figure 1 shows a schematic configuration diagram of the fuel cell system 1 of this embodiment. As shown in Figure 1, the fuel cell system 1 of this embodiment comprises 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 illustrative diagram of a part of the FC stack 11 shown in Figure 2.

[0031] [About FC stacks] The FC stack 11 generates electricity by receiving a supply of fuel and an oxidizer. In this embodiment, the fuel is hydrogen gas and the oxidizer is air. The FC stack 11 generates electricity by receiving a supply of hydrogen gas from the hydrogen system 21 and an air supply from the air system 22. The electricity generated by the FC stack 11 is supplied to a battery and an inverter (not shown). The cooling system 23 cools the FC stack 11 using a cooling medium. The FC stack 11 corresponds to an example of a "fuel cell" in this disclosed technology.

[0032] As shown in Figures 1 and 2, in this embodiment, the FC stack 11 is composed of multiple fuel cell cells 13 stacked on top of each other. Between adjacent fuel cell cells 13, block-shaped porous bodies 18 are arranged to form channels through which cooling water flows. The porous body 18 is a material having numerous fine gaps or pores inside. Examples of porous bodies 18 include sponges, sponge-like materials, filters, porous ceramics, and porous metals. The porous body 18 has properties such as permeability and absorbency and is used in various fields. Cooling water is an example of a "cooling medium" in this disclosed technology.

[0033] [About hydrogen systems] The hydrogen system 21 is installed 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.

[0034] The hydrogen supply passage 31 is a passage for supplying hydrogen gas from the hydrogen tank 41, where 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.

[0035] The hydrogen supply passage 31 is equipped 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 the filling port 42.

[0036] The hydrogen valve 51 is a valve that switches between supplying and shutting off hydrogen gas from the hydrogen tank 41 to the hydrogen supply passage 31, and is composed of multiple devices, such as a solenoid valve. The hydrogen pressure reducing valve 52 is a pressure regulating valve for reducing the pressure of hydrogen gas, and is composed of a solenoid valve, for example. The injector 53 is a device that injects hydrogen gas introduced from the hydrogen tank 41 to the downstream side, and is composed of a solenoid valve, for example. The injector 53 is configured to adjust the discharge pressure (hydrogen pressure) of hydrogen gas by adjusting the opening of the injection port by moving a needle valve, for example.

[0037] An exhaust and drain valve 57 is provided in the hydrogen discharge passage 32. The exhaust and drain valve 57 is a valve that switches between discharging and shutting off hydrogen off-gas and moisture from the FC stack 11, and is composed of, for example, a solenoid valve.

[0038] [Regarding the 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.

[0039] 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.

[0040] The air compressor 71 is an electrically powered 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, or in the air discharge passage 62 downstream of the FC stack 11. In other words, the FC stack 11 in this embodiment is configured to receive air directly from the air compressor 71 and to discharge air-off gas directly to the outside from the FC stack 11.

[0041] [Regarding the cooling system] As shown in Figures 1 and 2, the cooling system 23 includes a cooling water circulation channel 81 that circulates cooling water through each porous body 18. A heat exchanger 82 and a water tank 83 are provided in the cooling water circulation channel 81. The cooling water circulation channel 81 corresponds to an example of a "cooling medium circulation channel" in this disclosed technology.

[0042] The heat exchanger 82 is positioned downstream of the FC stack 11 on the cooling water circulation channel 81. In this embodiment, the heat exchanger 82 is configured so that the cooling water flowing through the cooling water circulation channel 81 can exchange heat with the hydrogen gas flowing through the hydrogen supply passage 31.

[0043] In this embodiment, the heat exchanger 82 is provided with a first fan 88 for cooling the heat exchanger 82 by blowing air. The first fan 88 is, for example, an electric fan driven by an electric motor.

[0044] The water tank 83 is located upstream of the FC stack 11 on the cooling water circulation channel 81. The water tank 83 is configured to store the cooling water that has been heat-exchanged (cooled) and liquefied (condensed) in the heat exchanger 82.

[0045] The FC stack 11 is provided with an inlet shroud 85 on the cooling water inflow side and an outlet shroud 86 on the cooling water outflow side. The inlet shroud 85 covers the inflow side of the FC stack 11 to allow cooling water to flow into each of the inlet sides of the multiple porous bodies 18. The downstream end of the cooling water circulation channel 81 is connected to the inlet 85a of the inlet shroud 85. The outlet shroud 86 covers the outflow side of the FC stack 11 to collect the cooling water (water vapor) flowing out from the outlet sides of the multiple porous bodies 18. The upstream end of the cooling water circulation channel 81 is connected to the outlet 86a of the outlet shroud 86. The cooling water circulation channel 81 is composed of a closed loop through 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.

[0046] As shown in Figure 2, cooling water flows through the central pipe 82a of the heat exchanger 82. Hydrogen gas supplied to the FC stack 11 flows around this central pipe 82a. Hydrogen gas at approximately 20°C flows into the heat exchanger 82. Cooling water at approximately 60°C flows into the central pipe 82a. In the heat exchanger 82, the hydrogen gas is heated to approximately 55°C and supplied to the FC stack 11. The cooling water is cooled from 60°C to approximately 52°C and flows into the water tank 83. The cooling water that flows from the water tank 83 to the FC stack 11 is drawn into the porous body 18 by the capillary force of the porous body 18.

[0047] As shown in Figure 3, a single fuel cell cell 13 consists of an electrode material 14 that serves as a heat source and a pair of separators 15 that sandwich the electrode material 14. The electrode material 14 is composed of an electrolyte membrane sandwiched between a pair of catalyst layers. Cooling water drawn into the porous body 18 is drawn in from its inlet side (bottom side in Figure 3) by the capillary force of the porous body 18. At this time, the heat generated by the electrode material 14 is transferred to the porous body 18 via the separators 15, causing the cooling water inside the porous body 18 to change into water vapor, which then evaporates from the outlet side (top side in Figure 3), releasing heat. The latent heat of vaporization of the porous body 18 at this time cools the fuel cell cell 13. The heat transfer coefficient of latent heat of vaporization is overwhelmingly higher than that of air cooling or water cooling.

[0048] [Regarding the control of the fuel electronics system] The fuel cell system 1 further includes a control device 10 for controlling the system 1. The control device 10 includes, for example, an arithmetic processing unit such as a CPU, a storage unit including a ROM that stores control programs and control data processed by the CPU, a RAM used as various work areas for control processing, and an input / output interface unit. The control device 10 is configured to perform various controls on the fuel cell system 1 according to the control programs stored in the storage unit. In particular, in this embodiment, the control device 10 is configured to control the cooling system 23 in order to control the cooling of the FC stack 11.

[0049] To control the cooling system 23, the FC stack 11 is equipped with a temperature sensor 89 for measuring the temperature of the FC stack 11. This temperature sensor 89 is positioned on the FC stack 11 so as to measure its overall average temperature. Alternatively, the temperature sensor 89 can be configured by placing multiple temperature sensors at multiple locations on the FC stack 11 and calculating the average value of the measurements from the multiple temperature sensors.

[0050] In this embodiment, the control device 10 is configured to control the first fan 88 so that the airflow rate corresponds to the measurement value of the temperature sensor 89. That is, when the temperature of the FC stack 11 rises, the control device 10 is configured to increase the airflow rate of the first fan 88 in order to lower the temperature of the FC stack 11 and increase the amount of cooling water condensed in the heat exchanger 82. In this embodiment, the control device 10 corresponds to an example of the "first control unit" of the disclosed technology.

[0051] [Regarding the operation of the fuel cell system] In the fuel cell system 1 configured as described above, the hydrogen gas supplied to the FC stack 11 from the hydrogen supply passage 31 is used for power generation in the FC stack 11, and then discharged from the FC stack 11 as hydrogen off-gas to the outside of the fuel cell system 1 via the hydrogen discharge passage 32. Similarly, the air supplied to the FC stack 11 from the air supply passage 61 is used for power generation in the FC stack 11, and then discharged from the FC stack 11 as air off-gas to the outside of the fuel cell system 1 via the air discharge passage 62.

[0052] The electricity generated by the FC stack 11 is either supplied to the battery to charge it, or supplied to the inverter to drive it. The inverter is also powered by the battery.

[0053] [Regarding the operation and effects of fuel cell systems] According to the configuration of the fuel cell system 1 of this embodiment described above, each fuel cell 13 is cooled by circulating cooling water through a cooling water circulation channel 81 to a porous body 18 placed between multiple fuel cell cells 13, thereby cooling the entire FC stack 11. In this configuration, the cooling water is drawn up through the capillary force of the porous body 18. In addition, the cooling water vaporizes in the porous body 18 due to heat from the fuel cell cells 13, thereby removing heat from the fuel cell cells 13 and cooling them. Furthermore, in the cooling water circulation channel 81, the cooling water is cooled by heat exchange with hydrogen gas and returned to the FC stack 11. Moreover, since the cooling water circulation channel 81 is configured as a closed loop in which only cooling water circulates, the cooling water is not released to the outside. Therefore, the cooling water can be used efficiently to cool the FC stack 11 while suppressing the consumption of cooling water.

[0054] In this embodiment, the cooling water is drawn up by the capillary force of the porous body 18, so the cooling water circulates through the cooling water circulation channel 81 without the use of power equipment. Therefore, the FC stack 11 can be cooled without using electricity. In addition, by placing the porous body 18 between adjacent fuel cell cells 13, the dimensions of the FC stack 11 in the stacking direction can be reduced. For example, in conventional air cooling systems, an air channel with a thickness of about "3 mm" was required between adjacent fuel cell cells. However, in this embodiment, the thickness of the porous body 18 can be set to "1 mm", and the stacking dimensions of the FC stack 11 can be reduced.

[0055] According to the configuration of this embodiment, in the cooling water circulation channel 81, the cooling water is cooled by heat exchange with hydrogen gas in the heat exchanger 82. Furthermore, since the heat exchanger 82 is cooled by the airflow from the first fan 88, the cooling (heat exchange) of the cooling water in the heat exchanger 82 is promoted. As a result, the cooling efficiency of the FC stack 11 by the cooling water can be improved.

[0056] Furthermore, according to the configuration of this embodiment, the control device 10 controls the first fan 88 so that the airflow rate corresponds to the temperature of the FC stack 11 measured by the temperature sensor 89. Therefore, the amount of cooling for the FC stack 11 is adjusted according to the temperature of the FC stack 11. This improves the controllability of the amount of cooling for the FC stack 11. In other words, the amount of cooling for the FC stack 11 can be controlled according to the temperature of the FC stack 11.

[0057] Furthermore, 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 are provided on the supply side of the air system 22 other than the air compressor 71, nor are any air valves or the like provided on the discharge side of the air system 22. As a result, the air system 22 can be simplified, and the cost of the fuel cell system 1 can be reduced.

[0058] <Second Embodiment> Next, the 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 the differences will be the focus of the description.

[0059] [Regarding the cooling system] This embodiment differs from the first embodiment in terms of the configuration of the cooling system 23. Figure 4 shows a schematic configuration diagram of the fuel cell system 1 of this embodiment. As shown in Figure 4, in this embodiment, the heat exchanger 82 is not provided with a first fan 88. Instead, a second fan 91 is placed in the cooling water circulation channel 81 between the outlet side (outlet shroud 86) of the porous body 18 of the FC stack 11 and the heat exchanger 82 to provide flow to the cooling water (water vapor) in the channel 81. The second fan 91 is, for example, an electric fan driven by an electric motor.

[0060] [Regarding the control of the fuel electronics system] In this embodiment, the control device 10 is configured to control the second fan 91 so that the flow of steam supplied by the second fan 91 in the cooling water circulation channel 81 has a flow velocity corresponding to the measurement value of the temperature sensor 89. That is, when the temperature of the FC stack 11 rises, the control device 10 is configured to increase the flow velocity of steam due to the rotation of the second fan 91 in order to lower the temperature of the FC stack 11, and to actively send the steam generated in the porous body 18 to the heat exchanger 82, thereby promoting the vaporization of the cooling water in the porous body 18. In this embodiment, the control device 10 corresponds to an example of the "third control unit" of this disclosed technology.

[0061] [Regarding the operation and effects of fuel cell systems] As described above, the configuration of the fuel cell system 1 of this embodiment provides the same functionality and effects as the first embodiment. In particular, unlike the first embodiment, in this embodiment, the second fan 91 provides flow to the cooling water (steam) in the cooling water circulation channel 81 from the outlet side of the porous body 18 to the heat exchanger 82, thereby promoting the cooling of the cooling water (steam) in the heat exchanger 82. As a result, the cooling efficiency of the FC stack 11 by the cooling water can be improved.

[0062] According to the configuration of this embodiment, the control device 10 controls the second fan 91 so that the flow of water vapor supplied by the second fan 91 becomes a flow velocity corresponding to the temperature of the FC stack 11 measured by the temperature sensor 89. Therefore, the amount of cooling of the FC stack 11 is adjusted according to the temperature of the FC stack 11. This improves the controllability of the amount of cooling of the FC stack 11. In other words, the amount of cooling of the FC stack 11 can be controlled according to the temperature of the FC stack 11.

[0063] <Third Embodiment> Next, a third embodiment will be described in detail with reference to the drawings.

[0064] [Regarding the cooling system] This embodiment differs from the previous embodiments in terms of the configuration of the cooling system 23. Figure 5 shows a schematic configuration diagram of the fuel cell system 1 of this embodiment. As shown in Figure 5, in this embodiment, the cooling water circulation channel 81 does not have a second fan 91. Instead, a water pump 93 is placed in the cooling water circulation channel 81 between the inlet side (inlet shroud 85) of the porous body 18 of the FC stack 11 and the water tank 83 to pump the cooling water in the channel 81. The water pump 93 is, for example, an electric pump driven by an electric motor.

[0065] [Regarding the control of the fuel electronics system] In this embodiment, the control device 10 is configured to control the water pump 93 so that the flow rate of cooling water from the cooling water circulation channel 81 to the FC stack 11 corresponds to the measurement value of the temperature sensor 89. That is, when the temperature of the FC stack 11 rises, the control device 10 increases the amount of water absorbed by the porous body 18, thereby increasing the amount of cooling water vaporized in the porous body 18.

[0066] [Regarding the operation and effects of fuel cell systems] According to the configuration of the fuel cell system 1 of this embodiment described above, the same functions and effects as those of the previous embodiments can be obtained. In addition, in this embodiment, unlike the previous embodiments, cooling water is pumped by the water pump 93 through the cooling water circulation channel 81 between the inlet side of the porous body 18 and the water tank 83, so the amount of water supplied to the porous body 18 increases. As a result, the cooling efficiency of the FC stack 11 by the cooling water can be improved.

[0067] According to the configuration of this embodiment, the control device 10 controls the water pump 93 so that the flow rate of the cooling water pumped by the water pump 93 corresponds to the flow rate of the FC stack 11 measured by the temperature sensor 89. Therefore, the amount of cooling of the FC stack 11 is adjusted according to the temperature of the FC stack 11. This improves the controllability of the amount of cooling of the FC stack 11. In other words, the amount of cooling of the FC stack 11 can be controlled according to the temperature of the FC stack 11.

[0068] <Fourth Embodiment> Next, a fourth embodiment will be described in detail with reference to the drawings.

[0069] [Regarding the cooling system] This embodiment differs from the previous embodiments in terms of the configuration of the cooling system 23. Figure 6 shows a schematic configuration diagram of the fuel cell system 1 of this embodiment. As shown in Figure 6, in this embodiment, the heat exchanger 82 is not provided with a first fan 88, and the cooling water circulation passage 81 is not provided with a second fan 91 or a water pump 93. Instead, the air supply passage 61 is provided with an air bypass passage 64 and a valve device 66.

[0070] The air bypass passage 64 is connected to the air supply passage 61 so that air is routed from the air supply passage 61, bypassing the FC stack 11, passing through the heat exchanger 82, and returning to the air supply passage 61. In other words, the upstream end of the air bypass passage 64 is connected to the air supply passage 61 directly downstream of the air compressor 71. The downstream end of the air bypass passage 64 is connected to the air supply passage 61 directly upstream of the FC stack 11.

[0071] The valve device 66 is configured to open and close the connection between the air supply passage 61 and the air bypass passage 64, and to open and close the air bypass passage 64 with a variable opening degree. The valve device 66 consists of a first solenoid valve 67, a second solenoid valve 68, and a third solenoid valve 69. The first solenoid valve 67 is located at the upstream end of the air bypass passage 64. The third solenoid valve 69 is located at the downstream end of the air bypass passage 64. The second solenoid valve 68 is located in the air supply passage 61 between the connection point with the upstream end of the air bypass passage 64 and the connection point with the downstream end of the air bypass passage 64. In this embodiment, all solenoid valves 67 to 69 are configured with a variable opening degree.

[0072] [Regarding the control of the fuel electronics system] In this embodiment, the control device 10 controls the valve device 66 so that the air flowing through the air bypass passage 64 has a flow rate corresponding to the measurement value of the temperature sensor 89. That is, when the temperature of the FC stack 11 rises, the control device 10 is configured to control the opening and closing and degree of opening of the valve device 66 so that a large amount of air flows through the air bypass passage 64 in order to lower the temperature of the FC stack 11. In other words, by flowing air through the air bypass passage 64, the air is used for heat exchange in the heat exchanger 82, and more stable heat exchange (cooling) of the cooling water is performed in the heat exchanger 82.

[0073] For example, if the heat exchange (cooling) of the cooling water in the heat exchanger 82 is sufficient with only heat exchange with hydrogen gas, the control device 10 closes the first solenoid valve 67 and the third solenoid valve 69, and opens only the second solenoid valve 68. This prevents air from flowing through the air bypass passage 64. On the other hand, if the heat exchange (cooling) of the cooling water in the heat exchanger 82 is insufficient with only heat exchange with hydrogen gas, or if the amount of cooling of the cooling water in the heat exchanger 82 needs to be controlled, the control device 10 opens all solenoid valves 67 to 69 and controls the opening degree of each solenoid valve 67 to 69. This allows air to flow through the air bypass passage 64 and controls its flow rate. In this embodiment, the control device 10 corresponds to an example of the "second control unit" of the disclosed technology.

[0074] [Regarding the operation and effects of fuel cell systems] With the configuration of the fuel cell system 1 of this embodiment described above, the same functions and effects as those of the previous embodiments can be obtained. In addition, in this embodiment, unlike the previous embodiments, by opening and closing the valve device 66 to a variable degree, air that bypasses the FC stack 11 passes through the air bypass passage 64, through the heat exchanger 82, and returns to the air supply passage 61. This promotes the cooling of the cooling water in the heat exchanger 82. Therefore, the cooling efficiency of the FC stack 11 by the cooling water can be improved.

[0075] According to the configuration of this embodiment, the control device 10 controls the valve device 66 so that the air flowing through the air bypass passage 64 has a flow rate corresponding to the temperature of the FC stack 11 measured by the temperature sensor 89. Therefore, the amount of cooling for the FC stack 11 is adjusted according to the temperature of the FC stack 11. This improves the controllability of the amount of cooling for the FC stack 11. In other words, the amount of cooling for the FC stack 11 can be controlled according to the temperature of the FC stack 11.

[0076] <Another embodiment> Furthermore, this disclosed technology is not limited to the embodiments described above, and it may be implemented by appropriately modifying some parts of the configuration without departing from the spirit of the disclosed technology.

[0077] (1) In each of the above embodiments, the fuel cell system 1 is implemented in an electric vehicle, but the fuel cell system can also be implemented in objects other than electric vehicles.

[0078] (2) In each of the above embodiments, air valves and the like were not provided on the supply side and discharge side of the air system 22, but air valves and the like may be provided.

[0079] (3) In each of the above embodiments, a closed cathode system in which the cooling system and the air system are separate has been described, but the embodiments can also be applied to an open cathode system in which the cooling system and the air system are common. [Industrial applicability]

[0080] This disclosed technology can be used, for example, in fuel cell systems installed in electric vehicles. [Explanation of Symbols]

[0081] 1. Fuel cell system 10 Control device (first control unit, second control unit, third control unit) 11 FC Stack (Fuel Cell) 13 fuel cell cells 18 Porous material 21 Hydrogen-based 22 Air System 31. Hydrogen supply passage (fuel supply passage) 61 Air supply passage (oxidizer supply passage) 64 Air bypass passage (oxidizer bypass passage) 66 Valve device 81 Cooling water circulation channel (cooling medium circulation channel) 82 Heat exchanger 88 First Fan 89 Temperature Sensor 91 Second Fan

Claims

1. A fuel cell consisting of multiple stacked fuel cell cells, A fuel supply passage for supplying fuel to the aforementioned fuel cell, An oxidant supply passage for supplying an oxidant to the aforementioned fuel cell, A porous body is placed between adjacent fuel cell cells and constitutes a channel through which a cooling medium flows. In a fuel cell system equipped with, The porous body further comprises a cooling medium circulation channel for circulating the cooling medium, The cooling medium circulation channel is configured such that the cooling medium can exchange heat with at least one of the fuel and the oxidizer, and is a closed loop through which only the cooling medium circulates. A fuel cell system characterized by the following features.

2. In the fuel cell system according to claim 1, A heat exchanger is arranged in the cooling medium circulation channel and configured so that the cooling medium can exchange heat with the fuel, To cool the heat exchanger, a first fan blows air toward the heat exchanger. A fuel cell system characterized by having the following features.

3. In the fuel cell system according to claim 2, A temperature sensor for measuring the temperature of the fuel cell, A first control unit for controlling the first fan and Equipped with, The first control unit controls the first fan so that the airflow rate corresponds to the measurement value of the temperature sensor. A fuel cell system characterized by the following features.

4. In the fuel cell system according to claim 1, A heat exchanger is arranged in the cooling medium circulation channel and configured so that the cooling medium can exchange heat with the fuel, An oxidant bypass passage is provided, which allows the oxidant to pass from the oxidant supply passage through the heat exchanger, bypassing the fuel cell, and return to the oxidant supply passage. A valve device for opening and closing the connection between the oxidant supply passage and the oxidant bypass passage, and for opening and closing the oxidant bypass passage to a variable degree. A fuel cell system characterized by having the following features.

5. In the fuel cell system according to claim 4, A temperature sensor for measuring the temperature of the fuel cell, A second control unit for controlling the valve device and Equipped with, The second control unit controls the valve device so that the flow rate of the oxidizer through the oxidizer bypass passage corresponds to the flow rate measured by the temperature sensor. A fuel cell system characterized by the following features.

6. In the fuel cell system according to claim 1, A heat exchanger is arranged in the cooling medium circulation channel and configured so that the cooling medium can exchange heat with the fuel, A second fan is positioned in the cooling medium circulation channel between the outlet side of the porous body and the heat exchanger, and is used to provide flow to the cooling medium. A fuel cell system characterized by having the following features.

7. In the fuel cell system according to claim 6, A temperature sensor for measuring the temperature of the fuel cell, A third control unit for controlling the second fan and Equipped with, The third control unit controls the second fan so that the flow of the cooling medium supplied by the second fan becomes a flow velocity corresponding to the measurement value of the temperature sensor. A fuel cell system characterized by the following features.

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