Fuel cell system

Abstract

To provide a fuel cell system that enables dehumidification of anode off-gas with a simpler configuration. [Solution] A fuel cell system in one embodiment of the present disclosure comprises a fuel cell, a fuel gas supply path, an anode off-gas discharge path, an off-gas circulation path, an injector connected to a hydrogen tank and capable of supplying fuel gas, and an injection distance setting device for setting the injection distance between the point where the recirculated anode off-gas merges with the fuel gas supply path and the injection point of the fuel gas from the injector. The dew point of the anode off-gas recirculated to the fuel gas supply path is adjusted by the injection of fuel gas via the injector based on this injection distance.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system applied to, for example, a fuel cell vehicle.

Background Art

[0002] A fuel cell system supplies a fuel (hydrogen) gas to one electrode (fuel electrode) and an oxygen gas to the other electrode (air electrode), and obtains electrical energy by the reaction between them.

[0003] In a fuel cell vehicle equipped with a fuel cell system, fuel gas ("fresh hydrogen" also called) is supplied from a high-pressure hydrogen tank filled with fuel gas to a fuel cell through a fuel gas supply system. As exemplified in Patent Documents 1 to 3, etc., the fuel gas discharged from the fuel cell (also called "anode off-gas") can be circulated to the fuel gas supply system through various circulation paths.

[0004] The anode off-gas discharged from the fuel cell is generally a gas in a highly humid state. Therefore, depending on the operating mode of the fuel cell such as the scavenging operation mode, removing moisture with a gas-liquid separator is not sufficient, and appropriate dehumidification of the anode off-gas is required when it is supplied to the fuel gas supply system again.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, challenges remain with current technology, not limited to the aforementioned patent documents. According to the aforementioned patent documents, anode off-gas can be dehumidified using dehumidifiers or heat exchangers, but this requires additional equipment, increasing costs. Furthermore, when a fuel cell system is installed in a vehicle, space must be secured to install the additional equipment for dehumidification, which reduces the flexibility of the vehicle's layout design.

[0007] This disclosure has been made in view of the above-mentioned problems as an example, and aims to provide a fuel cell system that can dehumidify anode off-gas with a simpler configuration. [Means for solving the problem]

[0008] To solve the above problems, a fuel cell system in one embodiment of the present disclosure comprises a fuel cell; a fuel gas supply path connected to the anode flow path of the fuel cell through which fuel gas flows; an anode off-gas discharge path through which anode off-gas discharged from the anode flow path flows; an off-gas circulation path having an off-gas circulation inlet connected to the anode off-gas discharge path and an off-gas circulation confluence port connected to the fuel gas supply path, for recirculating the anode off-gas from the anode off-gas discharge path to the fuel gas supply path; an injector connected to a hydrogen tank for storing the fuel gas and capable of supplying the fuel gas to the fuel gas supply path; and an injection distance setting device for setting the injection distance between the confluence position of the recirculated anode off-gas to the fuel gas supply path and the injection position of the fuel gas from the injector, wherein the dew point of the anode off-gas recirculated to the fuel gas supply path is adjusted by the injection of the fuel gas via the injector based on the injection distance. [Effects of the Invention]

[0009] According to the fuel cell system of this disclosure, the dew point of the anode off-gas is adjusted by fuel gas injected from multiple injectors, each with a different injection distance relative to the confluence position of the anode off-gas, thereby enabling dehumidification of the anode off-gas with a simpler configuration. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the functional block of a fuel cell vehicle equipped with a fuel cell system according to the first embodiment. [Figure 2] This is a schematic diagram showing the configuration of the anode gas system and cathode gas system of the fuel cell system according to the first embodiment. [Figure 3] This is a schematic diagram illustrating the configuration of the injector and injection distance setting device according to the first embodiment. [Figure 4] This is a schematic diagram showing the configuration of a control device and peripheral devices as an injection distance setting device included in the fuel cell system according to the first embodiment. [Figure 5] This is a schematic diagram illustrating how the injection amount for each injector is determined in an injection distance setting device. [Figure 6] This is a timing chart that can be executed in the dehumidification process of anode off-gas according to the first embodiment. [Figure 7] This is a schematic diagram showing the configuration of the anode gas system and cathode gas system of the fuel cell according to the second embodiment. [Figure 8] This is a schematic diagram illustrating the configuration of the injector and injection distance setting device according to the second embodiment. [Modes for carrying out the invention]

[0011] ≪First Embodiment≫ A preferred embodiment of the present disclosure will be described. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted. In addition, for components other than those described in detail below, the elemental technologies and configurations of known fuel cell systems and fuel cell vehicles including the above-mentioned patent documents may be appropriately supplemented.

[0012] <Fuel cell vehicle FCV> FIG. 1 schematically shows a configuration example of a fuel cell vehicle FCV including a fuel cell FC according to this embodiment. As an example, the fuel cell vehicle FCV is configured as a four-wheel drive vehicle that transmits the driving torque output from a driving power source 21 that generates the driving torque of the vehicle to the left front wheel 3LF, the right front wheel 3RF, the left rear wheel 3LR, and the right rear wheel 3RR (hereinafter, collectively referred to as "wheel 3" when no particular distinction is required). The driving power source 21 can be exemplified by a known electric motor disposed on the front wheel side in this embodiment.

[0013] As the electric motor as the driving power source 21 of this embodiment, one may be disposed on each of the front wheel side and the rear wheel side, or one electric motor may be disposed on each wheel 3. In addition to the above-mentioned electric motor, the driving power source 21 may further include an internal combustion engine such as a gasoline engine, a diesel engine, or a gas turbine engine.

[0014] The power source that supplies desired power to the driving power source 21 is constituted by a fuel cell system including a fuel cell FC. More specifically, the fuel cell FC of this embodiment has a stack structure in which a plurality of known fuel cell cells each having an electromotive force of about 1V are connected in series.

[0015] The fuel cell FC can be exemplified by a known PEFC (polymer electrolyte fuel cell), for example. The fuel cell FC is connected to a load including, for example, the driving power source 21 via a converter 22 and wiring. The current and voltage in the fuel cell FC are detected by a known current sensor SR1 and voltage sensor SR2, respectively, as illustrated in FIG. 1.

[0016] As shown in FIG. 1, the fuel cell system can be electrically connected to the secondary battery 50 and a known converter 22. The secondary battery 50 can store the electric power generated by the fuel cell system or the electric power generated by regeneration. Examples of such a secondary battery 50 include known secondary batteries such as lithium ion secondary batteries and lead storage batteries.

[0017] The converter 22 includes a known AC / DC converter that converts direct current and alternating current, and a known DC / DC converter that adjusts the voltage of the direct current to a desired voltage. As an example, the converter 22 of the present embodiment has a function of setting the output voltage generated and output by the fuel cell FC in response to a control signal from the control device 10, and a function of boosting the electric power generated by the fuel cell FC to a desired voltage when supplying the electric power to a load.

[0018] As equipment used for driving control, the fuel cell vehicle FCV of the present embodiment includes the above-described drive power source 21, an electric steering device 8, and brake devices 4LF, 4RF, 4LR, and 4RR (hereinafter, collectively referred to as "brake device 4" when no particular distinction is required).

[0019] The drive power source 21 outputs drive torque that is transmitted to the front-wheel drive shaft 2F and the rear-wheel drive shaft 2R via a transmission (not shown), a front-wheel differential mechanism 5F, and a rear-wheel differential mechanism 5R. The driving of the drive power source 21 and the transmission is controlled by a known control device including one or more electronic control units (ECUs: Electronic Control Unit).

[0020] An electric steering device 8 is provided on the front-wheel drive shaft 2F. The electric steering device 8 includes an electric motor (not shown) and a gear mechanism, and adjusts the steering angles of the left front wheel 3LF and the right front wheel 3RF by being controlled by the vehicle drive control device 20.

[0021] The vehicle drive control device 20 includes one or more known electronic control units (ECUs) that control the drive of a power source 21 that outputs drive torque to a fuel cell vehicle (FCV), an electric steering device 8 that controls the steering angle of the steering wheel 9 or steering wheels, and a brake device 4 that controls the braking force of the fuel cell vehicle (FCV). The vehicle drive control device 20 may also have a function to control the drive of a transmission that changes the speed of the output output from the power source 21 and transmits it to the wheels 3.

[0022] <Fuel cell system> Figure 2 shows the configuration of the anode gas system and cathode gas system of the fuel cell system according to the first embodiment. The fuel cell system of this embodiment includes an anode gas system including a known hydrogen tank 23 capable of supplying fuel gas to the fuel cell FC, and a cathode gas system including a known compressor 36 capable of supplying oxygen gas (air) to the fuel cell FC.

[0023] As shown in Figure 2, the cathode gas system is configured to supply oxygen gas (air) to the fuel cell (FC). The cathode gas system may include a cathode gas supply path 34 connected to the cathode flow path OFP of the fuel cell (FC), and a known compressor 36 and humidifier 37 installed in the cathode gas supply path 34. The cathode gas supply path 34 may also be further provided with known mechanisms such as a flow control valve and an intercooler.

[0024] The cathode gas system is configured to exhaust oxygen gas (cathode off gas) emitted from the fuel cell (FC). The cathode gas system is connected to the cathode flow path OFP of the fuel cell (FC) and includes a cathode off gas discharge passage 35 through which cathode gas and moisture flow. A known back pressure valve 41 may be provided in the cathode off gas discharge passage 35.

[0025] As shown in Figure 2, the anode gas system is configured to supply fuel gas (hydrogen) to the fuel cell FC. The anode gas system includes a fuel gas supply passage 30 through which fuel gas flows, connected to the anode flow path HFP of the fuel cell FC and the hydrogen tank 23, and an anode off-gas discharge passage 31 through which anode off-gas discharged from the anode flow path HFP flows.

[0026] As shown in the figure, the fuel gas supply passage 30 of this embodiment is provided with an injection volume control valve 45, an injector 24, and a moisture capture mechanism 26 from the upstream side (hydrogen tank side) to the downstream side (fuel cell side). The injection volume control valve 45 can be exemplified by a known solenoid valve that has the function of adjusting the injection volume of fuel gas injected from the hydrogen tank 23.

[0027] The injector 24 is connected to a hydrogen tank 23 that stores fuel gas and has the function of supplying fuel gas to the fuel gas supply line 30. Specific examples of the injector 24 are not particularly limited as long as it can inject fuel gas, and known hydrogen gas discharge devices can be cited as examples.

[0028] The moisture capture mechanism 26 is located downstream (on the fuel cell side) of the fuel gas supply passage 30, below the anode off-gas confluence point (off-gas circulation confluence port 32b). Specific examples of such a moisture capture mechanism 26 include known filters such as metal mesh or resin mesh that can capture moisture in the gas.

[0029] An off-gas circulation path 32 is connected to the fuel gas supply path 30 in this embodiment. The off-gas circulation path 32 has an off-gas circulation inlet 32a connected to the anode off-gas discharge path 31 and an off-gas circulation confluence port 32b connected to the fuel gas supply path 30. The off-gas circulation path 32 has the function of recirculating anode off-gas from the anode off-gas discharge path 31 to the fuel gas supply path 30. The off-gas circulation path 32 is provided with a known circulation pump 38 and a flow control valve 44, such as a known solenoid valve, which can adjust the flow rate of anode off-gas.

[0030] As shown in Figure 2, the anode gas system is configured to exhaust fuel gas (anode off-gas) discharged from the fuel cell FC. The anode gas system includes an anode off-gas discharge passage 31 through which the anode off-gas flows, connected to the anode flow path HFP of the fuel cell FC.

[0031] The anode-off gas discharge channel 31 is connected to a known gas-liquid separator 25. A first water discharge channel 33b is connected to the gas-liquid separator 25. The water separated in the gas-liquid separator 25 can be discharged to the outside by opening and closing a water discharge valve 42 located on the first water discharge channel 33b. The water recovered by the gas-liquid separator 25 may be reused in the fuel cell system.

[0032] On the other hand, the gaseous component of the anode off-gas separated in the gas-liquid separator 25 is discharged through the gas discharge passage 33a. The off-gas circulation passage 32 described above is connected to the gas discharge passage 33a via a known three-way valve 43. The control device 10 can recirculate a portion of the anode off-gas to the fuel gas supply passage 30 via the off-gas circulation passage 32 by controlling this three-way valve 43. The control device 10 can also release (exhaust) a portion of the anode off-gas into the atmosphere by controlling this three-way valve 43.

[0033] <Dehumidifier using recirculated anode gas> Referring to Figures 2 and 3, the injector 24 and injection distance setting device (control device 10) that function as a cathode gas dehumidifier in this embodiment will be described in detail. As shown in Figures 2 and 3, an anode gas dehumidifier is provided in the fuel gas supply passage 30 of this embodiment. The anode gas dehumidifier has the function of dehumidifying the anode off-gas that is recirculated to the fuel gas supply passage 30, particularly via the off-gas circulation passage 32.

[0034] The injectors 24 of this embodiment are provided in a plurality in the fuel gas supply passage 30 at predetermined intervals and spaced apart from each other along the direction of fuel gas flow. More specifically, the injectors 24 of this embodiment include a first injector 24A located at the downstream end of the hydrogen tank 23 and a distance L1 upstream from the off-gas circulation confluence port 32b, a second injector 24B located upstream of the first injector 24A and a distance L2 (L2>L1) upstream from the off-gas circulation confluence port 32b, and a third injector 24C located further upstream of the second injector 24B and a distance L3 (L3>L2) upstream from the off-gas circulation confluence port 32b.

[0035] The injector 24 of this embodiment is composed of the three components described above, but it is sufficient to include at least two first injectors 24A and second injectors 24B that are positioned at different distances upstream from the off-gas circulation confluence port 32b. Furthermore, the first distance L1 to the third distance L3 described above can be appropriately determined by experiment or simulation depending on the desired dehumidification capacity and device layout.

[0036] Such a fuel cell system can be controlled by a control device 10. In this embodiment, the control device 10 functions as an injection distance setting device. The control device 10 is also called an FCCU (Fuel Cell Control Unit) and is configured to include one or more processors, such as a CPU (Central Processing Unit), and one or more memories, such as a RAM (Random Access Memory) or ROM (Read Only Memory), which are connected to the processors in a manner that allows communication. The FCCU described above may also be mounted in a fuel cell vehicle (FCV) as an ECU (Electronic Control Unit) that controls the vehicle's drive.

[0037] The control device 10 may be configured to connect to a known external network NET, such as the Internet, via various known communication devices CD, such as a smartphone, as an example. The compressor 36, each valve, and known sensors SR, such as the current sensor SR1 and voltage sensor SR2, are electrically connected to such a control device 10 either directly or via communication means such as CAN (Controller Area Network) or LIN (Local Internet).

[0038] The control device 10, acting as an injection distance setting device, sets the injection distance between the point where the recirculated anode off-gas merges with the fuel gas supply passage 30 (off-gas circulation junction port 32b) and the injection point of the fuel gas from the injector 24. Based on the injection distance set above, the control device 10 adjusts the dew point of the anode off-gas that is recirculated to the fuel gas supply passage by the injection of fuel gas via the injector 24.

[0039] <Dehumidification power adjustment based on injectors with different spray distances> The dehumidification mechanism of the anode off-gas according to this embodiment will now be described. When fresh, high-pressure hydrogen stored in the hydrogen tank 23 is injected by the injector 24, this fuel gas undergoes adiabatic expansion immediately after injection.

[0040] Since the temperature of the fuel gas undergoing adiabatic expansion decreases, in this embodiment, fresh hydrogen is blown onto the anode off-gas that merges at the off-gas circulation confluence port 32b, thereby lowering the dew point of the recirculated anode off-gas and performing dehumidification. At this time, the temperature of the new hydrogen injected into the anode off-gas depends greatly on the injection distance described above. Specifically, the new hydrogen injected from the third injector 24C, which is set to a relatively long third distance L3, reaches a temperature of T1°C when it reaches the off-gas circulation confluence port 32b. Temperature T1 can be exemplified by a temperature near ambient temperature.

[0041] In contrast, the new hydrogen injected from the first injector 24A, which is set to a relatively short injection distance L1, is injected at a position relatively close to the off-gas circulation confluence port 32b, and therefore reaches a temperature of T6°C by the time it reaches the off-gas circulation confluence port 32b. Note that temperature T6 is an extremely low temperature (for example, 0°C) that is lower than temperature T1.

[0042] As described above, the fresh hydrogen injected from the injector 24 receives heat from the outside air via the fuel gas supply passage 30. Therefore, the longer the distance and time from injection to reaching the off-gas circulation confluence port 32b, the closer its temperature gets to ambient temperature (outside temperature). In this embodiment, this phenomenon is applied to adjust the temperature of the fresh hydrogen at the point where it merges with the recirculating anode off-gas, by adjusting the combination of the first injectors 24A to the third injector 24C that inject the fresh hydrogen and the injection time.

[0043] In this embodiment, as an example, a total of three injectors are provided in the fuel gas supply line 30: a first injector 24A for cryogenic use, a second injector 24B for low temperature use, and a third injector 24C for ambient temperature use. As mentioned above, the number of injectors installed in the fuel gas supply line 30 is not limited to the three described above, and may be determined as appropriate through experiments and simulations depending on the accuracy of dew point adjustment and the scale of the piping. Furthermore, the maximum injection volume of fresh hydrogen from each injector may be set to be the same for all of them, or there may be differences between the injectors. For example, the third injector 24C on the room temperature side may be composed of an injector with a larger maximum injection volume than the first injector 24A and the second injector 24B.

[0044] The installation positions of the first injector 24A to the third injector 24C may be adjusted as appropriate depending on the temperature at the off-gas circulation confluence port 32b. In addition, the first injector 24A to the third injector 24C may inject new hydrogen individually, or they may inject new hydrogen in parallel in cooperation with other injectors. As an example, Table 1 shows an example of the drive pattern of the first injector 24A to the third injector 24C described above.

[0045] [Table 1]

[0046] For example, in drive pattern 1, new hydrogen is injected only from the third injector 24C. Therefore, in this drive pattern 1, new hydrogen at a temperature of T1°C is blown onto the recirculating anode off-gas at the off-gas circulation confluence port 32b. Furthermore, in drive pattern 5, for example, new hydrogen is injected in parallel from the second injector 24B and the third injector 24C. Therefore, in this drive pattern 5, new hydrogen at a temperature of T5°C is blown onto the recirculating anode off-gas at the off-gas circulation confluence port 32b.

[0047] As is clear from Table 1, the injection distance setting device of this embodiment can adjust the dew point of the recirculated anode off gas by controlling at least one of the injection amount and injection time of the fuel gas (fresh hydrogen) injected from each of the multiple injectors.

[0048] The injection times of the new hydrogen injected from at least two injectors may be the same, or one may be injected continuously while the other is injected intermittently. Furthermore, the injection amounts of the new hydrogen injected from at least two injectors may be the same, or different amounts may be injected. These injection times and amounts of new hydrogen can be appropriately set depending on the target temperature of the new hydrogen when it reaches the off-gas circulation confluence port 32b.

[0049] The anode off-gas, thus recirculated in the fuel gas supply line 30, is temperature-controlled by the new hydrogen that reaches the off-gas circulation confluence port 32b, becoming a high-humidity gas. Subsequently, this high-humidity fuel gas (a mixture of new hydrogen and anode off-gas) passes through the moisture capture mechanism 26 located downstream. At this point, the high-humidity fuel gas has excess moisture captured by the moisture capture mechanism 26 before being supplied to the anode flow path HFP of the fuel cell FC.

[0050] As described above, the anode-off gas discharge channel 31 is connected to the gas-liquid separator 25. Also, as shown in Figure 2, the moisture capture mechanism 26 may be connected to the gas-liquid separator 25 via the second water discharge channel 39. In this way, the water removed from the fuel gas in a high-humidity state by the moisture capture mechanism 26 flows to the gas-liquid separator 25 via the second water discharge channel 39. Thus, the second water discharge channel 39 is connected to both the gas-liquid separator 25 and the moisture capture mechanism 26, and has the function of circulating the moisture captured by the moisture capture mechanism 26 to the gas-liquid separator 25.

[0051] <Injection distance setting device (control device 10)> Next, the control device 10, which serves as the injection distance setting device, will be described with reference to Figures 4 to 6. As shown in Figure 4, the control device 10 of this embodiment is configured to include an FC moisture content measuring unit 10A, a hydrogen supply amount measuring unit 10B, an injector control unit 10C, a valve control unit 10D, and a notification control unit 10E.

[0052] (FC moisture content measurement unit) The FC moisture content measurement unit 10A is equipped with a function to measure the amount of moisture present in the fuel cell FC described above. For example, the FC moisture content measurement unit 10A measures the amount of moisture in the fuel cell FC based on the current value and voltage value of the fuel cell FC obtained from the current sensor SR1 and voltage sensor SR2 described above, and the temperature value of the fuel cell FC obtained from a temperature sensor (not shown). As a method for measuring the amount of moisture in the fuel cell, for example, a known hygrometer may be installed downstream of the off-gas circulation confluence port 32b, or a known measurement method disclosed in Japanese Patent Application Publication No. 2020-123458, Japanese Patent Application Publication No. 2021-128909, or Japanese Patent Application Publication No. 2023-128754 may be applied. Furthermore, in this embodiment, the FC moisture content measurement unit 10A calculates the amount of moisture in the entire fuel cell stack, but it may also measure the amount of moisture in the anode flow path, for example, as shown in Japanese Patent Application Publication No. 2020-123458.

[0053] The FC moisture content measurement unit 10A outputs the moisture content deviation in the fuel cell FC based on the target value for the appropriate moisture content in the fuel cell FC and the measured moisture content obtained above. The target value for the appropriate moisture content in a fuel cell (FC) may be set in advance through experiments or simulations, for example, or calculated using known methods such as those described in publication WO2010 / 073380. Furthermore, the target value for the appropriate moisture content in a fuel cell (FC) may be set according to, for example, the required output of the fuel cell (FC) or the operating state of the fuel cell vehicle.

[0054] (Hydrogen supply measurement unit) The hydrogen supply amount measuring unit 10B has a function to measure the amount of hydrogen supplied to the fuel cell FC for power generation based on the output requirement value required for the fuel cell FC. Such an output requirement value may change depending on the operating state of the fuel cell vehicle (FCV), as referred to, for example, in Japanese Patent Application Publication No. 2016-122624. The hydrogen supply amount measuring unit 10B may measure the amount of hydrogen supplied based on the output requirement value of the fuel cell FC by various known methods disclosed, for example, in Japanese Patent Application Publication No. 2004-146075 and Japanese Patent Application Publication No. 2016-95906. The hydrogen supply amount measurement unit 10B outputs the hydrogen supply amount obtained in this manner as the hydrogen supply request value.

[0055] (Injector control unit) The injector control unit 10C controls the injection amount and injection time of fuel gas (fresh hydrogen) from the injectors 24 installed in the fuel gas supply passage 30. The injector control unit 10C functions as part of the injection distance setting device described above. As illustrated in Figures 5 and 6, the injector control unit 10C calculates the appropriate amount of moisture for the fuel gas supplied to the fuel cell FC based on the hydrogen supply request value and moisture content deviation described above, and determines the injection amount and injection time of fresh hydrogen injected from each of the multiple injectors 24 according to this calculation result.

[0056] Thus, the injection distance setting device (control device 10) in this embodiment can set the injection distance from a predetermined injector 24 to the confluence position (off-gas circulation confluence port 32b) according to the moisture state of the fuel cell FC. In other words, the injection distance setting device (control device 10) in this embodiment can control the degree of dehumidification of the anode off-gas by the injection ratio of each injector (for example, at least one of the ratio of injection amount and the ratio of injection time).

[0057] If the moisture content in the fuel cell FC is below the target value mentioned above, excessive dehumidification of the anode off-gas may be avoided by, for example, increasing the drive ratio of the third injector 24C on the ambient temperature side. On the other hand, if the moisture content in the fuel cell FC is excessively high, dehumidification of the anode off-gas may be actively performed by, for example, increasing the drive ratio of the first injector 24A or the second injector 24B on the low temperature side.

[0058] (Valve control section) The valve control unit 10D adjusts the opening degree of the injection amount control valve 45 corresponding to each injector 24 based on the injection amount and injection time of fresh hydrogen determined by the injector control unit 10C described above. As illustrated by "Injector Injection Amount" in Figure 6, the valve control unit 10D can perform control that drives all of the multiple injectors 24 during a certain period, while stopping some of the multiple injectors while driving others during other periods.

[0059] For example, if the FC output requirement increases, the amount of fuel injected from the injectors will increase accordingly. In the initial stage shown in Figure 6, only the third injector 24C is driven, and then all injectors 24 are driven in parallel. In Figure 6, following the initial phase, the FC output requirement increases steadily. During this period, the amount of moisture inside the fuel cell FC also increases significantly. Therefore, as shown in the figure, fresh hydrogen may be injected from the second injector 24B and the third injector 24C to help control humidity. Thus, although the amount of moisture generated increases when the fuel cell FC reaches a high output state, in this embodiment, it is possible to control the injection amount from each injector 24 to assist in dehumidification so that the fuel gas flowing into the anode flow path HFP does not contain excessive moisture.

[0060] Subsequently, if the moisture content of the fuel cell FC becomes higher than the target value (the period during which the measured value exceeds the target value in Figure 6), the third injector 24C may stop while the other injectors 24 continue to operate to increase the dehumidification capacity.

[0061] As a result, fresh hydrogen injected from a predetermined injector 24 and controlled to the desired temperature is blown onto the recirculating anode off-gas at the off-gas circulation confluence port 32b. The fresh hydrogen mixed with the anode off-gas is then supplied to the anode flow path HFP of the fuel cell FC as a fuel gas corresponding to the FC output requirement.

[0062] (Notification Control Unit) The notification control unit 10E executes a process to display various information, such as the fuel cell system 100 and the vehicle status, on the notification device PD. In this embodiment, the notification device PD can be, for example, a well-known display DP or speaker SP, as shown in the figure. The notification control unit 10E may also execute a control to display the above-mentioned information on an external terminal, such as a smartphone, carried by the occupants of the fuel cell vehicle (FCV).

[0063] As described above, in the fuel cell system of the first embodiment, the dew point of the anode off-gas is adjusted by fuel gas (fresh hydrogen) injected from multiple injectors, each with a different injection distance relative to the confluence position of the recirculated anode off-gas. This makes it possible to condense the moisture in the anode off-gas with a simpler configuration, and for example, the anode off-gas can be dehumidified by removing the condensed moisture.

[0064] ≪Second Embodiment≫ <Fuel cell system 110> Figures 7 and 8 show a fuel cell system according to the second embodiment of this disclosure. In the second embodiment described below, the differences from the first embodiment described above will be mainly explained, and configurations that perform the same functions as in the first embodiment will be given the same reference numerals and their explanations will be omitted as appropriate.

[0065] In the first embodiment described above, the off-gas circulation path 32 was connected to the fuel gas supply path 30 via a single confluence point (off-gas circulation confluence port 32b) (see Figure 3). In contrast, the off-gas circulation path 32 of the second embodiment is mainly characterized by being connected to the fuel gas supply path 30 at multiple different confluence points. In other words, in the first embodiment, the injection distance was set by adjusting the injection amount from multiple injectors arranged along the direction of fuel gas flow, but in the second embodiment, the injection distance can be set by adjusting multiple confluence points arranged along this flow direction.

[0066] In other words, as shown in Figures 7 and 8, the off-gas circulation path 32 in the second embodiment is configured to include a plurality of circulation gas confluence ports (first off-gas circulation confluence port 32b1, second off-gas circulation confluence port 32b2, and third off-gas circulation confluence port 32b3) that branch off before joining the fuel gas supply path 30 and are spaced at predetermined intervals along the direction of fuel gas flow.

[0067] In the second embodiment, the off-gas circulation path 32 branches into three paths downstream from the circulation pump 38, each joining the fuel gas supply path 30. Specifically, the off-gas circulation path 32 in this embodiment includes a first branch passage 32x that joins the fuel gas supply path 30 at a distance of first distance L1 downstream from the first injector 24A, and a third branch passage 32z that joins the fuel gas supply path 30 at a distance D2 further downstream from the second branch passage 32y.

[0068] As shown in Figure 8, the first branch channel 32x is provided with a first flow rate control valve 44A, the second branch channel 32y is provided with a second flow rate control valve 44B, and the third branch channel 32z is provided with a third flow rate control valve 44C. This allows the injection distance setting device (control device 10) to adjust the flow rate of the anode off gas that merges through these multiple circulating gas confluence ports, thereby enabling more precise control of the dew point of the recirculated anode off gas.

[0069] In this case, the injection distance setting device (control device 10) can supply anode-off gas to the fuel gas supply passage 30 via only the third branch passage 32z by, for example, closing the first flow control valve 44A and the second flow control valve 44B and opening the third flow control valve 44C. Alternatively, the injection distance setting device (control device 10) can supply anode-off gas to the fuel gas supply passage 30 in parallel from the first branch passage 32x and the third branch passage 32z by, for example, closing the second flow control valve 44B and opening the first flow control valve 44A and the third flow control valve 44C. Thus, the injection distance setting device (control device 10) of this embodiment can change the junction position of the anode-off gas to the fuel gas supply passage 30 via the aforementioned flow control valves 44.

[0070] Although the fuel cell system of the second embodiment also illustrates three injectors, the first injector 24A to the third injector 24C, the dehumidification capacity in this embodiment does not depend solely on the number of injectors, so it is not necessary to have multiple injectors 24. For example, in the fuel cell system of the second embodiment, a single injector configuration is possible, such as having only the first injector 24A installed.

[0071] While preferred embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the present disclosure is not limited to such examples. It is obvious to any person with ordinary skill in the art to which the present disclosure pertains to attempt further modifications to these embodiments and variations within the scope of the technical idea set forth in the claims, and these modifications will naturally also fall within the technical scope of the present disclosure.

[0072] For example, in the second embodiment described above, the off-gas circulation path 32 was branched into three and connected to the fuel gas supply path 30, but it may also be branched into two or four or any number of paths and connected to the fuel gas supply path 30. Furthermore, although the fuel cell systems of each embodiment described above were installed in fuel cell vehicles (FCVs), they may also be installed in forms other than vehicles, such as in aircraft or stationary equipment. [Explanation of symbols]

[0073] 10: Control device, 23: Hydrogen tank, 24: Injector, 25: Gas-liquid separator, 26: Moisture capture mechanism, 30: Fuel gas supply line, 31: Anode off-gas discharge line, 32: Off-gas circulation line, 33a: Gas discharge line, 33b: First water discharge line, 34: Cathode gas supply line, 35: Cathode off-gas discharge line, 36: Compressor, 37: Humidifier, 38: Circulation pump, 39: Second water discharge line

Claims

1. Fuel cells and A fuel gas supply path connected to the anode flow path of the fuel cell through which fuel gas flows, An anode off-gas discharge channel through which the anode off-gas discharged from the above anode flow path flows, An off-gas circulation path has an off-gas circulation inlet connected to the anode off-gas discharge path and an off-gas circulation confluence connected to the fuel gas supply path, and recirculates the anode off-gas from the anode off-gas discharge path to the fuel gas supply path, An injector connected to a hydrogen tank for storing the fuel gas and capable of supplying the fuel gas to the fuel gas supply line, The system includes an injection distance setting device for setting the injection distance between the point where the recirculated anode off-gas merges with the fuel gas supply path and the injection point of the fuel gas from the injector, The dew point of the anode off-gas, which is recirculated to the fuel gas supply line, is adjusted by the injection of the fuel gas through the injector based on the injection distance. Fuel cell system.

2. The injectors are provided in the fuel gas supply passage in a plurality, spaced apart from each other at predetermined intervals along the direction of flow of the fuel gas. The injection distance setting device controls at least one of the injection amount and injection time of the fuel gas injected from each of the plurality of injectors to adjust the dew point of the recirculated anode off-gas. The fuel cell system according to claim 1.

3. The aforementioned plurality of injectors are A first injector positioned a distance of a first distance upstream from the off-gas circulation confluence port, The fuel cell system according to claim 2, further comprising: a second injector positioned upstream of the off-gas circulation confluence by a second distance greater than the first distance.

4. The off-gas circulation path includes a plurality of circulation gas confluence ports that branch off and merge into the fuel gas supply path at predetermined intervals along the direction of fuel gas flow, The injection distance setting device controls the dew point of the recirculated anode off-gas by adjusting the flow rate of the anode off-gas that merges through the plurality of circulating gas confluence ports. The fuel cell system according to claim 1.

5. Each of the branched side channels corresponding to the multiple circulating gas confluence ports is equipped with a flow control valve, The injection distance setting device changes the junction position of the anode off-gas to the fuel gas supply path via the flow control valve. The fuel cell system according to claim 4.

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