Fuel cell systems and material handling machinery

Abstract

The present invention provides a fuel cell system and cargo handling machinery that can effectively utilize the air discharged from the fuel cell while simplifying control. [Solution] The fuel cell system comprises a fuel cell, a drive unit driven by the electricity generated by the fuel cell, an air supply line for supplying air to the fuel cell, an air discharge line for discharging air from the fuel cell, an electric compressor provided on the air supply line, a turbine provided on the air discharge line, a turbine-driven compressor connected to the turbine and driveable by the turbine, a bypass line connecting the air supply line and the portion of the air discharge line upstream of the turbine, a switching unit capable of introducing at least a portion of the air being pumped toward the fuel cell into the bypass line, and a control device that controls the switching unit so as to increase the amount of air introduced into the bypass line when the load on the drive unit decreases.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system and a handling machine.

Background Art

[0002] Patent Document 1 discloses a fuel cell system. This fuel cell system includes a compressor and a turbine. The compressor compresses the air supplied to the fuel cell. The turbine is driven by the exhaust gas generated in the fuel cell. The shaft of the compressor can be electrically driven by an electric motor. Further, the compressor and the turbine are mechanically connected via a shaft. The turbine assists the electric motor when the compressor is driven.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the fuel cell system described in Patent Document 1, the air pressurized by the compressor flows into the turbine through the fuel cell. Therefore, a time delay of several seconds occurs between when the compressor pumps the air and when the air flows into the turbine. When the rotational speed of the electric motor is varied due to this time delay, the rotational speed of the turbine varies with a delay of several seconds. When the rotational speed of the turbine varies, the rotational speed of the electric motor required for the rotation of the compressor varies. In order to cope with such variations in rotational speed, complicated control of the electric motor has been required.

[0005] This disclosure was made to solve the above-mentioned problems and aims to provide a fuel cell system and cargo handling machine that can effectively utilize the air discharged from the fuel cell while simplifying control. [Means for solving the problem]

[0006] To solve the above problems, the fuel cell system according to the present disclosure comprises a fuel cell, a drive unit driven by the electricity generated by the fuel cell, an air supply line for supplying air to the fuel cell, an air discharge line for discharging air from the fuel cell, an electric compressor provided in the air supply line and capable of pressurizing and pumping air toward the fuel cell, a turbine provided in the air discharge line and driven by the air flowing through the air discharge line, a turbine-driven compressor connected to the turbine and driveable by the turbine, a bypass line connecting the air supply line and the portion of the air discharge line upstream of the turbine, a switching unit capable of introducing at least a portion of the air pressurized and pumped toward the fuel cell into the bypass line, and a control device that controls the switching unit so as to increase the amount of air introduced into the bypass line when the load on the drive unit decreases.

[0007] Furthermore, the fuel cell system according to this disclosure includes a fuel cell, a drive unit driven by electricity generated by the fuel cell, an air supply line for supplying air to the fuel cell, an air discharge line for discharging air from the fuel cell, an electric compressor provided in the air supply line and capable of pressurizing and pumping air toward the fuel cell, a turbine provided in the air discharge line and driven by air flowing through the air discharge line, a turbine-driven compressor provided in the air supply line upstream of the electric compressor and connected to the turbine and driveable by the turbine, a first branch line connecting the portion of the air supply line upstream of the turbine-driven compressor and the portion of the air supply line between the turbine-driven compressor and the electric compressor, and a first branch valve capable of opening and closing the first branch line.

[0008] Furthermore, the material handling machine according to this disclosure comprises the fuel cell system described above, a gantry-type frame, wheels supporting the frame, and a crane attached to the frame, wherein at least one of the wheels and the crane is driven by the drive unit. [Effects of the Invention]

[0009] According to the fuel cell system and cargo handling machinery of this disclosure, it is possible to simplify control while effectively utilizing the air discharged from the fuel cell. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a cargo handling machine according to the first embodiment of this disclosure. [Figure 2] This is a schematic diagram of a fuel cell system according to the first embodiment of this disclosure. [Figure 3] This is a functional block diagram of a control device according to the first embodiment of this disclosure. [Figure 4] This flowchart shows the procedure for the control method during startup of a fuel cell according to the first embodiment of this disclosure. [Figure 5] It is a flowchart showing the procedure of the control method when the output of the fuel cell according to the first embodiment of the present disclosure decreases. [Figure 6] It is a flowchart showing the procedure of the control method before starting the fuel cell according to the first embodiment of the present disclosure. [Figure 7] It is a schematic configuration diagram of the fuel cell system according to the second embodiment of the present disclosure. [Figure 8] It is a schematic configuration diagram of the fuel cell system according to the third embodiment of the present disclosure. [Figure 9] It is a schematic configuration diagram of the fuel cell system according to the fourth embodiment of the present disclosure. [Figure 10] It is a functional block diagram of the control device according to the fourth embodiment of the present disclosure. [Figure 11] It is a flowchart showing the procedure of the control method when starting the fuel cell according to the fourth embodiment of the present disclosure. [Figure 12] It is a flowchart showing the procedure of the control method when the output of the fuel cell according to the fourth embodiment of the present disclosure decreases. [Figure 13] It is a schematic configuration diagram of the fuel cell system according to the fifth embodiment of the present disclosure. [Figure 14] It is a flowchart showing the procedure of the control method when starting the fuel cell according to the fifth embodiment of the present disclosure. [Figure 15] It is a schematic configuration diagram of the fuel cell system according to the sixth embodiment of the present disclosure. [Figure 16] It is a schematic configuration diagram of the fuel cell system according to the seventh embodiment of the present disclosure. [Figure 17] It is a schematic configuration diagram of the fuel cell system according to the eighth embodiment of the present disclosure. [Figure 18] It is a hardware configuration diagram according to each embodiment of the present disclosure.

Mode for Carrying Out the Invention

[0011] <First Embodiment> Hereinafter, the cargo handling machine 1 and the fuel cell system 10 according to the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 6.

[0012] (Configuration of Cargo Handling Machine) As shown in FIG. 1, the cargo handling machine 1 of this embodiment is a RTG crane (Rubber Tired Gantry crane). The RTG crane transports cargo M (such as containers, etc.) at, for example, ports. The cargo handling machine 1 includes a frame 2, wheels 3, a crane 4, and a fuel cell system 10.

[0013] (Frame) The frame 2 is formed in a portal shape. Specifically, the frame 2 is formed in a U shape that opens downward when viewed from the front-rear direction. The frame 2 includes leg portions 2a, support columns 2b, and a beam portion 2c. The leg portions 2a are formed in a rod shape extending in the front-rear direction. A pair of leg portions 2a are provided spaced apart in the left-right direction. Two support columns 2b are provided on each leg portion 2a spaced apart in the front-rear direction. The support columns 2b extend in the vertical direction. The beam portion 2c extends in the left-right direction and connects the upper ends of two adjacent support columns 2b in the left-right direction. Two beam portions 2c are provided side by side in the front-rear direction.

[0014] (Wheels) A plurality (four in the illustrated example) of wheels 3 are provided on each leg portion 2a. A plurality of wheels 3 arranged in the front-rear direction are provided on each leg portion 2a. The plurality of wheels 3 support each leg portion 2a from below.

[0015] (Crane) The crane 4 is attached to the beam portion 2c. The crane 4 has a pedestal portion 4a, a wire 4b, and a hook portion 4c. The pedestal portion 4a spans across the two beam portions 2c. The wire 4b extends downward from the pedestal portion 4a. A plurality of wires 4b are provided. The hook portion 4c is suspended by the plurality of wires 4b. The hook portion 4c grips the cargo M.

[0016] The fuel cell system 10 includes a fuel cell 20. The fuel cell system 10 drives the wheels 3 and crane 4 described above using the power from the fuel cell 20. The fuel cell system 10 is mounted, for example, on the legs 2a of the frame 2 or the base 4a of the crane 4.

[0017] (Fuel cell system configuration) Next, the configuration of the fuel cell system 10 will be described. As shown in Figure 2, the fuel cell system 10 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 40, a cooling system 60, and a control device 70.

[0018] (fuel cell) The fuel cell 20 is a device that converts the chemical reaction energy of fuel and oxidizer into electrical energy. The fuel cell 20 has an anode 21 and a cathode 22. Fuel is supplied to the anode 21 and oxidizer is supplied to the cathode 22. Here, the fuel is hydrogen and the oxidizer is air. The hydrogen supplied to the fuel cell 20 is consumed by the fuel cell reaction. At this time, water is produced by the fuel cell reaction.

[0019] (Drive unit) The drive unit 11 is connected to the fuel cell 20 by a power line L11. The drive unit 11 is powered by the electricity generated by the fuel cell 20. The drive unit 11 is, for example, a travel motor that drives the wheels 3 or a drive motor that drives the crane 4. The drive unit 11 drives at least one of the wheels 3 and the crane 4 of the cargo handling machine 1.

[0020] (Inverter) The inverter 12 is installed on the power line L11. The power generated by the fuel cell 20 is supplied to the drive unit 11 via the inverter 12.

[0021] (controller) The controller 13 receives information such as the magnitude of the load on the drive unit 11 via the inverter 12. Based on the transmitted information, the controller 13 controls the rotational speed of the drive unit 11.

[0022] (Hydrogen-based) The hydrogen system 30 is a system that supplies hydrogen to the fuel cell 20. The hydrogen system 30 comprises a hydrogen supply line L21, a hydrogen discharge line L22, an injector 31, a first humidifier 32, a first gas-liquid separator 33, and a hydrogen circulation pump 34.

[0023] (Hydrogen supply line) The hydrogen supply line L21 is a pipe that supplies hydrogen from a hydrogen tank (not shown) to the fuel cell 20.

[0024] (Hydrogen emission line) The hydrogen discharge line L22 is a pipe that discharges hydrogen from the fuel cell 20. The hydrogen discharge line L22 discharges any hydrogen that is not consumed in the fuel cell reaction outside the fuel cell 20 and returns it to the hydrogen supply line L21.

[0025] (injector) The injector 31 is located in the hydrogen supply line L21. The injector 31 circulates hydrogen from the hydrogen tank to the fuel cell 20.

[0026] (1st humidifier) The first humidifier 32 is located between the injector 31 and the fuel cell 20 in the hydrogen supply line L21. The first humidifier 32 humidifies the hydrogen supplied to the fuel cell 20.

[0027] (1st gas-liquid separator) The first gas-liquid separator 33 is located in the hydrogen discharge line L22. The first gas-liquid separator 33 separates excess water from the hydrogen, which has become wet due to the water produced in the fuel cell reaction.

[0028] (Hydrogen circulation pump) The hydrogen circulation pump 34 pumps the hydrogen that has passed through the first gas-liquid separator 33 to the hydrogen supply line L21, circulating it within the hydrogen system 30.

[0029] (Air-based) The air system 40 is a system that supplies air to the fuel cell 20. The air system 40 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, a switching unit 49, a first branch line L35, a first branch valve 50, a second branch line L36, and a second branch valve 51.

[0030] (Air supply line) The air supply line L31 is a pipe that supplies air to the fuel cell 20.

[0031] (Air discharge line) The air discharge line L32 is a pipe that discharges air from the fuel cell 20.

[0032] (Compressor) The compressor 41 is a device that takes in air from the outside and pumps it to a device in the fuel cell system 10 that requires compressed air (in this embodiment, the fuel cell 20). In this embodiment, the compressor 41 is installed in multiple stages in the air supply line L31. Two compressors 41 are provided, and these two compressors 41 are connected in series. Of the two compressors 41 connected in series, the downstream (later stage) is an electric compressor 41a, and the upstream (earlier stage) is a turbine-driven compressor 41b. That is, the two compressors 41 include an electric compressor 41a and a turbine-driven compressor 41b.

[0033] (Electric compressor) The electric compressor 41a is installed in the air supply line L31. The electric compressor 41a is driven by the driving force of the electric motor 43, which will be described later. The power compressor 41 is installed to be able to pressurize and supply air toward the fuel cell 20.

[0034] (Turbine-driven compressor) The turbine-driven compressor 41b is connected to the turbine 42, which will be described later. The turbine-driven compressor 41b is designed to be driveable by the turbine 42. The turbine-driven compressor 41b is located upstream of the electric compressor 41a in the air supply line L31.

[0035] (Turbine) The turbine 42 is located in the air discharge line L32. The turbine 42 is driven by the air flowing through the air discharge line L32. The turbine 42 is connected to the turbine drive compressor 41b by a shaft. The rotational driving force of the turbine 42 is transmitted to the turbine drive compressor 41b via the shaft. This causes the turbine drive compressor 41b to rotate. In this embodiment, the turbine drive compressor 41b and the turbine 42 constitute a turbocharger.

[0036] (Electric motor) The electric motor 43 is connected to the electric compressor 41a. The electric motor 43 rotates the electric compressor 41a.

[0037] (heat exchanger) The heat exchanger 44 is installed so that the air supply line L31 and the air discharge line L32 pass through it. The heat exchanger 44 is installed in the air supply line L31 in the portion between the electric compressor 41a and the fuel cell 20. The heat exchanger 44 is also installed in the air discharge line L32 in the portion between the fuel cell 20 and the turbine 42. The heat exchanger 44 performs heat exchange between the air flowing through the air supply line L31 and the air flowing through the air discharge line L32. As a result, the air flowing through the air supply line L31 is cooled and the air flowing through the air discharge line L32 is heated.

[0038] (Intercooler) The intercooler 45 is located in the air supply line L31 between the heat exchanger 44 and the fuel cell 20. The intercooler 45 performs heat exchange between the air flowing through the air supply line L31 and the refrigerant supplied from the cooling system 60, which will be described later. This cools the air flowing through the air supply line L31.

[0039] (Second humidifier) The second humidifier 46 is located between the intercooler 45 and the fuel cell 20 in the air supply line L31. The second humidifier 46 humidifies the air supplied to the fuel cell 20.

[0040] (Second gas-liquid separator) The second gas-liquid separator 47 is located in the air discharge line L32 between the fuel cell 20 and the heat exchanger 44. The second gas-liquid separator 47 separates excess moisture from the air, which has become humid due to the moisture generated in the fuel cell reaction.

[0041] (Flow rate adjustment line) The flow rate adjustment line L33 is located in the air discharge line L32 between the bypass line L34 (described later) and the turbine 42. The flow rate adjustment line L33 diverts a portion of the air supplied to the turbine 42 to the outside of the turbine 42.

[0042] (Flow control valve) The flow control valve 48 is installed in the flow control line L33 so as to be openable and closable. By adjusting the opening degree of the flow control valve 48, the airflow rate supplied to the turbine 42 is adjusted. This adjusts the power of the turbine 42.

[0043] (Bypass line) The bypass line L34 is a pipe that connects the air inlet and air outlet of the fuel cell 20. The bypass line L34 connects the air supply line L31 and the portion of the air discharge line L32 upstream of the turbine 42. In this embodiment, the bypass line L34 connects the portion of the air supply line L31 between the fuel cell 20 and the electric compressor 41a and the portion of the air discharge line L32 upstream of the turbine 42.

[0044] (Switching section) The switching unit 49 is a valve mechanism that switches the flow rate of air being pumped towards the fuel cell 20. The switching unit 49 is capable of introducing at least a portion of the air being pumped towards the fuel cell 20 into the bypass line L34. The switching unit 49 is, for example, a three-way valve provided at the connection point between the air supply line L31 and the bypass line L34. Furthermore, by adjusting the opening degree of the switching unit 49, the amount of air introduced into the bypass line L34 can be increased or decreased.

[0045] (First branching line) The first branch line L35 is a pipe that diverts the air flowing through the air supply line L31 so that it does not pass through the turbine-driven compressor 41b. The first branch line L35 connects the portion of the air supply line L31 upstream of the turbine-driven compressor 41b to the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a.

[0046] (First branch valve) The first branch valve 50 is a valve that can open and close the first branch line L35.

[0047] (Second branch line) The second branch line L36 is a pipe that diverts the air flowing through the air supply line L31 so that it does not pass through the electric compressor 41a. The second branch line L36 connects the section of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a, and the section of the air supply line L31 between the electric compressor 41a and the bypass line L34.

[0048] (Second branch valve) The second branch valve 51 is a valve that can open and close the second branch line L36.

[0049] (cooling system) The cooling system 60 is a system for cooling the fuel cell 20. The cooling system 60 comprises a cooling line L41, a radiator 61, a fan 62, a pump 63, a refrigerant supply line L42, a refrigerant control valve 64, and a refrigerant return line L43.

[0050] (Cooling line) Cooling line L41 is a pipe through which refrigerant flows to cool the fuel cell 20. The refrigerant is, for example, antifreeze. Cooling line L41 circulates the refrigerant.

[0051] (Radiator) The radiator 61 is located in the cooling line L41. The radiator 61 cools the refrigerant by exchanging heat between the refrigerant that has passed through the fuel cell 20 and the outside air.

[0052] (fan) The fan 62 blows air to the radiator 61.

[0053] (pump) Pump 63 is located in the cooling line L41. Pump 63 pumps the refrigerant cooled by the radiator 61 towards the fuel cell 20.

[0054] (Refrigerant supply line) The refrigerant supply line L42 connects the portion of the cooling line L41 downstream of the pump 63 to the intercooler 45, between the pump 63 and the fuel cell 20. The refrigerant supply line L42 branches off a portion of the refrigerant that is pumped by the pump 63 and headed toward the fuel cell 20 and supplies it to the intercooler 45.

[0055] (Refrigerant control valve) The refrigerant control valve 64 is installed in the refrigerant supply line L42 so as to be openable and closable. By adjusting the opening degree of the refrigerant control valve 64, the flow rate of refrigerant supplied to the intercooler 45 is adjusted.

[0056] (Refrigerant return line) The refrigerant return line L43 connects the portion of the cooling line L41 downstream of the fuel cell 20 to the intercooler 45, between the fuel cell 20 and the radiator 61. The refrigerant return line L43 returns the refrigerant that has passed through the intercooler 45 to the cooling line L41.

[0057] (Control device) The control device 70 controls various equipment and devices that constitute the fuel cell system 10. As shown in Figure 3, the control device 70 has functional units such as an acquisition unit 71, an operation unit 72, and a determination unit 73.

[0058] (Acquisition Department) The acquisition unit 71 acquires information, signals, and commands transmitted from various devices and equipment that constitute the fuel cell system 10. For example, the acquisition unit 71 acquires a signal indicating a decrease in the load of the drive unit 11 via the inverter 12. The acquisition unit 71 also acquires information, signals, and commands input from external sources.

[0059] (Operation unit) The control unit 72 operates various devices and equipment that constitute the fuel cell system 10. The control unit 72 includes, for example, an electric compressor control unit 72a, a first branch valve control unit 72b, a second branch valve control unit 72c, and a switching control unit 72d.

[0060] (Electric compressor control unit) The electric compressor control unit 72a operates the electric compressor 41a based on the information and signals acquired by the acquisition unit 71.

[0061] (First branch valve operating section) The first branch valve operating unit 72b operates the first branch valve 50 based on the information and signals acquired by the acquisition unit 71.

[0062] (Second branch valve operating section) The second branch valve operating unit 72c operates the second branch valve 51 based on the information and signals acquired by the acquisition unit 71.

[0063] (Switching operation unit) The switching operation unit 72d operates the switching unit 49 based on the information and signals acquired by the acquisition unit 71.

[0064] For example, the switching operation unit 72d controls the switching unit 49 so that the amount of air introduced into the bypass line L34 increases when the load on the drive unit 11 decreases.

[0065] For example, the first branch valve operating unit 72b opens the first branch valve 50 when the fuel cell 20 is started. Then, with the first branch valve 50 open, the operating unit 72 drives the electric compressor 41a. After the electric compressor 41a has been driven, if backflow is detected in the first branch line L35, the first branch valve operating unit 72b closes the first branch valve 50.

[0066] For example, the switching operation unit 72d operates the switching unit 49 so that all of the air pumped by the electric compressor 41a is introduced into the bypass line L34 before the fuel cell 20 is started. Then, with all of the air pumped towards the fuel cell 20 introduced into the bypass line L34, the electric compressor operation unit 72a drives the electric compressor 41a.

[0067] (Judgment Department) The determination unit 73 determines the information of various devices and equipment constituting the fuel cell system 10 acquired by the acquisition unit 71. The determination unit 73 includes, for example, a reverse flow determination unit 73a and a pressure determination unit 73b.

[0068] (Backflow detection unit) The backflow determination unit 73a determines whether or not backflow has been detected in the first branch line L35.

[0069] (Pressure determination section) The pressure determination unit 73b determines whether the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to a predetermined pressure. The predetermined pressure is such that, when the second branch valve 51 is open, air does not flow back from the downstream side to the upstream side of the electric compressor 41a through the second branch line L36.

[0070] (Control method for fuel cell systems) Next, a control method for the fuel cell system 10 according to this embodiment will be described.

[0071] (Control method during fuel cell startup) First, the control method for starting up the fuel cell 20 will be explained with reference to the flowchart in Figure 4. First, the first branch valve operating unit 72b opens the first branch valve 50 (step S11). Then, with the first branch valve 50 open, the electric compressor operating unit 72a starts the electric motor 43 and drives the electric compressor 41a (step S12). At this time, because the first branch valve 50 is open, air is supplied to the electric compressor 41a through the first branch line L35 without any energy loss. Also, when the electric compressor 41a is driven, a flow toward the fuel cell 20 is created in the air supply line L31, and a flow is created toward the fuel cell 20 in the air discharge line L32. The turbine 42 is driven by the air flowing through the air discharge line L32. The driving force of the turbine 42 is transmitted to the turbine-driven compressor 41b, which drives the turbine-driven compressor 41b. When the turbine-driven compressor 41b is driven, the pressure downstream of the turbine-driven compressor 41b increases. As a result, backflow occurs in the first branch line L35.

[0072] After step S12, the backflow determination unit 73a determines whether or not backflow has been detected in the first branch line L35 (step S13). The method for detecting backflow in the first branch line L35 can be selected as appropriate. For example, backflow in the first branch line L35 may be detected by measuring the pressure on the downstream and upstream sides of the turbine-driven compressor 41b in the air supply line L31. Alternatively, backflow may be detected from the change in rotational speed of the turbine-driven compressor 41b. If backflow is detected in the first branch line L35 (step S13; YES), the first branch valve operation unit 72b closes the first branch valve 50 (step S14).

[0073] By following the above procedure, the electric compressor 41a and the turbine-driven compressor 41b are driven. This supplies air to the fuel cell 20, and the fuel cell 20 starts up.

[0074] (Control method when fuel cell output decreases) Furthermore, the control device 70 needs to control the output of the fuel cell 20 according to the load on the drive unit 11. Below, for example, the control method when the output of the fuel cell 20 decreases will be explained with reference to the flowchart in Figure 5.

[0075] For example, when the load on the drive unit 11 decreases, the inverter 12 sends a signal to the control device 70 to reduce the output of the fuel cell 20. First, the acquisition unit 71 acquires this signal to reduce the output of the fuel cell 20 (step S21).

[0076] After step S21, the switching operation unit 72d operates the switching unit 49 to increase the amount of air introduced into the bypass line L34 (step S22). In step S22, the completely closed bypass line L34 may be opened to start air flow in the bypass line L34, or the amount of air introduced into the bypass line L34 may be increased by increasing the opening of the bypass line L34, which was originally open. Step S22 increases the airflow rate supplied to the turbine 42 without passing through the fuel cell 20. At this time, the electric compressor operation unit 72a does not perform an operation to arbitrarily reduce the rotational speed of the electric compressor 41a. As the amount of air introduced into the bypass line L34 increases, the pressure downstream of the electric compressor 41a decreases.

[0077] After step S22, the pressure determination unit 73b determines whether the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to a predetermined pressure (step S23). The predetermined pressure is such that, when the second branch valve 51 is open, air does not flow back from the downstream side to the upstream side of the electric compressor 41a through the second branch line L36. If the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to the predetermined pressure (step S23; YES), the second branch valve operation unit 72c opens the second branch valve 51 (step S24).

[0078] After step S24, the electric compressor control unit 72a rotates the electric compressor 41a at a speed that does not stop it (step S25).

[0079] After step S25, the load on the drive unit 11 increases again, and when the airflow rate required for the fuel cell 20 exceeds the current airflow rate supplied to the fuel cell 20, the inverter 12 sends a signal to the control device 70 to increase the output of the fuel cell 20. The acquisition unit 71 then acquires this signal to increase the output of the fuel cell 20 (step S26).

[0080] When a signal is received to increase the output of the fuel cell 20, the control unit 72 increases the rotational speed of the electric compressor 41a (step S27).

[0081] In this way, when the output of the fuel cell 20 decreases, the air flow rate to the fuel cell 20 is adjusted. If the load on the drive unit 11 does not increase again, steps S26 to S27 are omitted.

[0082] (Control method before fuel cell startup) Furthermore, before starting up the fuel cell 20, the air system 40 may be operated alone (idling operation of the air system 40). The control method before starting up the fuel cell 20 will be explained below with reference to the flow chart in Figure 6.

[0083] First, the switching operation unit 72d operates the switching unit 49 to ensure that all the air pumped by the electric compressor 41a is introduced into the bypass line L34 (step S31). At this time, the flow path between the electric compressor 41a and the fuel cell 20 in the air supply line L31 is closed. Subsequently, the operation unit 72 drives the electric compressor 41a (step S32). This creates an airflow in the air discharge line L32 toward the turbine 42. The air flowing through the air discharge line L32 drives the turbine 42. The driving force of the turbine 42 is transmitted to the turbine drive compressor 41b, which drives the turbine drive compressor 41b. In this way, the air system 40 is maintained in operation.

[0084] Subsequently, when the acquisition unit 71 acquires a signal to start the fuel cell 20 (step S33), the switching operation unit 72d operates the switching unit 49 to open the flow path between the electric compressor 41a and the fuel cell 20 in the air supply line L31, and supplies the air pumped by the electric compressor 41a to the fuel cell 20 (step S34). With this control, the air system 40 is kept running before the fuel cell 20 is started, and air is immediately supplied to the fuel cell 20 at the timing to start the fuel cell 20.

[0085] (Effects and Benefits) The fuel cell system 10 and cargo handling machine 1 of this embodiment can achieve the following effects.

[0086] In this embodiment, the fuel cell system 10 includes a bypass line L34, a switching unit 49, and a control device 70. The bypass line L34 connects the air supply line L31 and the portion of the air discharge line L32 upstream of the turbine 42. The switching unit 49 is configured to allow at least a portion of the air being pumped to the fuel cell 20 to be introduced into the bypass line L34. The control device 70 controls the switching unit 49 so that the amount of air introduced into the bypass line L34 increases when the load on the drive unit 11 decreases. This allows the fuel cell system 10 to utilize the air discharged from the fuel cell 20 as power for the turbine 42. When the load on the drive unit 11 decreases and the output of the fuel cell 20 decreases, the control device 70 controls the switching unit 49 to increase the amount of air introduced into the bypass line L34. This allows the fuel cell system 10 to reduce the amount of air supplied to the fuel cell 20 without reducing the rotational speed of the electric compressor 41a. Therefore, it becomes unnecessary to change the rotational speed of the electric compressor 41a in response to a decrease in the output of the fuel cell 20. Specifically, it becomes unnecessary to apply a braking force to the electric motor 43 in the opposite direction to the rotational direction (negative direction) in order to reduce the rotational speed of the electric motor 43. As a result, it becomes unnecessary to adjust the braking force of the electric motor 43, and the control of the electric motor 43 is simplified.

[0087] Furthermore, in this embodiment, the turbine-driven compressor 41b is located upstream of the electric compressor 41a in the air supply line L31. This allows the fuel cell system 10 to gradually increase the air pressure using the electric compressor 41a and the turbine-driven compressor 41b, which are connected in series. Also, because the turbine-driven compressor 41b is located upstream of the electric compressor 41a, the air flow rate can be secured by the turbine-driven compressor 41b, and then the air pressure can be secured by the electric compressor 41a. Thus, the fuel cell system 10 can efficiently pump air to the fuel cell 20.

[0088] Furthermore, the air introduced into the bypass line L34 is supplied to the turbine 42 without passing through the fuel cell 20. This reduces the time delay that occurs between the compressor 41 pumping air and the air flowing into the turbine 42. As a result, the turbine-driven compressor 41b can vary the amount of air pumped to the fuel cell 20 with a response speed close to that of the electric compressor 41a.

[0089] Furthermore, the turbine 42 is supplied with air that does not lose energy in the fuel cell 20 through the bypass line L34. This increases the rotational speed of the turbine 42, and increases the amount of air pumped by the turbine-driven compressor 41b. As a result, the fuel cell system 10 can supply the necessary air to the fuel cell 20 even if the amount of air pumped by the electric compressor 41a is reduced. For example, when the fuel cell 20 starts at low output, such as when the drive unit 11 is idling, the fuel cell system 10 can drive the electric compressor 41a with the minimum power necessary to supply the amount of air required for the fuel cell 20.

[0090] Bypass line L34 connects the portion of air supply line L31 between the fuel cell 20 and the electric compressor 41a and the portion of air discharge line L32 upstream of the turbine 42.

[0091] As a result, the air that has been pumped by the electric compressor 41a is introduced into the bypass line L34. Therefore, compared to the case where the bypass line L34 is located upstream of the electric compressor 41a, the fuel cell system 10 can introduce more air into the bypass line L34.

[0092] Furthermore, in this embodiment, the control device 70 controls the switching unit 49 and the electric compressor 41a so that, before starting the fuel cell 20, the switching unit 49 is operated so that all of the air pumped by the electric compressor 41a is introduced into the bypass line L34, and the electric compressor 41a is driven in this state.

[0093] As a result, the fuel cell system 10 can maintain the air system 40 operating only before the fuel cell 20 is started, and can immediately supply air to the fuel cell 20 when it is time to start the fuel cell 20.

[0094] In this embodiment, the fuel cell system 10 further includes a first branch line L35 and a first branch valve 50. The first branch line L35 connects the portion of the air supply line L31 upstream of the turbine-driven compressor 41b to the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a. The first branch valve 50 is a valve that can open and close the first branch line L35. With this configuration, the fuel cell system 10 can introduce air to the electric compressor 41a without passing it through the turbine-driven compressor 41b by opening the first branch valve 50 when the fuel cell 20 is started. As a result, air without energy loss in the turbine-driven compressor 41b is introduced to the electric compressor 41a. Therefore, the electric compressor 41a can be driven efficiently when the fuel cell 20 is started. Subsequently, if backflow is detected in the first branch line L35, the first branch valve 50 is closed, allowing the fuel cell system 10 to stably drive the turbine-driven compressor 41b.

[0095] Furthermore, in this embodiment, the fuel cell system 10 includes a second branch line L36 and a second branch valve 51. The second branch line L36 connects the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a, and the portion of the air supply line L31 between the electric compressor 41a and the bypass line L34. The second branch valve 51 is a valve that can open and close the second branch line L36. With this configuration, for example, if the load on the drive unit 11 suddenly decreases and it becomes necessary to rapidly reduce the output of the fuel cell 20, the second branch valve 51 can be opened to prevent the air flowing through the air supply line L31 from passing through the electric compressor 41a. As a result, the amount of air supplied to the fuel cell 20 is further reduced, allowing the fuel cell system 10 to respond quickly to a sudden drop in output. Furthermore, in order to prevent backflow in the second branch line L36, it is necessary to open the bypass line L34 and open the second branch valve 51 when the pressure downstream of the electric compressor 41a in the air supply line L31 drops to a pressure that prevents backflow in the second branch line L36. Also, since the turbine-driven compressor 41b continues to rotate for a while due to inertia, it is not necessary to drive the electric compressor 41a until the flow rate of air supplied to the fuel cell 20 drops to a level below the flow rate required by the fuel cell 20.

[0096] Furthermore, the fuel cell system 10 can also naturally reduce the rotational speed of the turbine-driven compressor 41b by opening the first branch valve 50 and the second branch valve 51.

[0097] Furthermore, in this embodiment, the bypass line L34 connects the portion of the air supply line L31 between the electric compressor 41a and the heat exchanger 44, and the portion of the air discharge line L32 between the heat exchanger 44 and the turbine 42. As a result, high-temperature air that does not pass through the heat exchanger 44 or intercooler 45 is supplied to the turbine 42. Therefore, the input energy of the turbine 42 increases. In addition, when the output of the fuel cell 20 decreases, excess air does not flow to the heat exchanger 44 or intercooler 45, thus suppressing cooling losses.

[0098] In this embodiment, the fuel cell system 10 further includes a flow rate adjustment line L33 and a flow rate adjustment valve 48. The flow rate adjustment line L33 is provided in the portion of the air discharge line L32 between the bypass line L34 and the turbine 42. The flow rate adjustment line L33 diverts a portion of the air supplied to the turbine 42 to the outside of the turbine 42. The flow rate adjustment valve 48 is provided on the flow rate adjustment line L33 so as to be openable and closable. Thus, the fuel cell system 10 can open the flow rate adjustment valve 48 and introduce air into the flow rate adjustment line L33 to reduce the amount of air introduced into the turbine 42, thereby lowering the rotational speed of the turbine 42. Alternatively, instead of the flow rate adjustment line L33 and the flow rate adjustment valve 48, a wastegate valve may be provided on the exhaust side of the turbine 42.

[0099] Furthermore, the cargo handling machine 1 (RTG crane) is required to operate under highly variable conditions, such as having a waiting time between the arrival of cargo M, when hoisting up cargo M such as containers. The cargo handling machine 1 in this embodiment is equipped with the fuel cell system 10 described above. Therefore, for example, in operation requiring maximum output, the cargo handling machine 1 can complete the increase in output in the shortest possible time and quickly bring the turbine 42 to the optimal operating point. This makes it possible to reduce the amount of hydrogen fuel required for the operating cycle of the cargo handling machine 1.

[0100] Furthermore, during standby, it is necessary to minimize hydrogen consumption while preparing for rapid acceleration when the next cargo M arrives. By controlling the fuel cell system 10 described above, the cargo handling machine 1 can minimize the use of auxiliary power sources such as the compressor 41 and cooling system 60, thereby improving fuel efficiency.

[0101] <Second Embodiment> Hereinafter, a fuel cell system 110 according to the second embodiment of this disclosure will be described with reference to Figure 7. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 110 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0102] As shown in Figure 7, the fuel cell system 110 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 140, a cooling system 60, and a control device 70. The air system 140 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, a switching unit 49, a first branch line L35, a first branch valve 50, a second branch line L36, and a second branch valve 51. The air system 140 in this embodiment further comprises an assist electric motor 52.

[0103] (Assist electric motor) The assist electric motor 52 is connected to the turbine-driven compressor 41b. The assist electric motor 52 assists in driving the turbine-driven compressor 41b. The assist electric motor 52 is driven by the control device 70.

[0104] The fuel cell system 110 according to this embodiment is controlled in the same manner as in the first embodiment. In this embodiment, for example, the control method for starting up the fuel cell 20, the control method for when the output of the fuel cell 20 decreases, and the control method for before starting up the fuel cell 20 are executed in the same manner as in the first embodiment.

[0105] (Effects and Benefits) The fuel cell system 110 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 110 of this embodiment can achieve the following effects and advantages.

[0106] In this embodiment, the fuel cell system 110 further includes an assist electric motor 52 that assists the turbine-driven compressor 41b. By controlling the assist electric motor 52, it becomes possible to control the rotational speed setting of the turbine-driven compressor 41b. Therefore, the turbine-driven compressor 41b can operate at an efficient operating point.

[0107] <Third Embodiment> Hereinafter, a fuel cell system 210 according to the third embodiment of this disclosure will be described with reference to Figure 8. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 210 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0108] As shown in Figure 8, the fuel cell system 210 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 240, and a cooling system 60. The air system 240 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, a switching unit 49, a first branch line L35, and a first branch valve 50.

[0109] In this embodiment, the bypass line L34 connects the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a, and the portion of the air discharge line L32 upstream of the turbine 42.

[0110] The fuel cell system 210 according to this embodiment is controlled in the same manner as in the first embodiment. In this embodiment, for example, the control method for starting up the fuel cell 20 and the control method for when the output of the fuel cell 20 decreases are executed in the same procedure as in the first embodiment. In this embodiment, since the second branch line L36 and the second branch valve 51 are not provided, step S24 is omitted in the control method for when the output of the fuel cell 20 decreases.

[0111] (Effects and Benefits) The fuel cell system 210 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 210 of this embodiment can achieve the following effects and advantages.

[0112] In this embodiment, the bypass line L34 may connect the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a and the portion of the air discharge line L32 upstream of the turbine 42.

[0113] As a result, air is introduced into the bypass line L34 without passing through the electric compressor 41a. Therefore, when the bypass line L34 is in use, air with low pressure loss flows into the turbine 42.

[0114] <Fourth Embodiment> Hereinafter, a fuel cell system 310 according to the fourth embodiment of this disclosure will be described with reference to Figures 9 to 12. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 310 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0115] As shown in Figure 9, the fuel cell system 310 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 340, a cooling system 60, and a control device 370. The air system 340 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 342, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a bypass line L34, a switching unit 49, a first branch line L35, a first branch valve 50, a second branch line L36, and a second branch valve 51.

[0116] The turbine 342 in this embodiment is a variable geometry turbine (VG) whose opening area of ​​the flow path through which air introduced from the air discharge line L32 passes can be adjusted. One form of a VG turbine is a turbine with a variable nozzle. This turbine with a variable nozzle is equipped with movable vanes, which are operated by actuators or motors, in the nozzle portion that blows exhaust gas (air in this embodiment) onto the turbine wheel. Multiple movable vanes are arranged on the outer circumference of the turbine wheel. By changing the position and angle of the movable vanes, the opening area of ​​the flow path for the air blown toward the turbine wheel is adjusted. When the opening area of ​​the flow path within the turbine 342 becomes smaller, the flow velocity increases, and the rotational speed of the turbine 342 increases. Conversely, when the opening area of ​​the flow path within the turbine 342 becomes larger, the flow velocity decreases, and the rotational speed of the turbine 342 decreases.

[0117] As shown in Figure 10, the control device 370 of this embodiment has, for example, an acquisition unit 71, an operation unit 372, and a determination unit 73. The operation unit 372 has an electric compressor operation unit 72a, a first branch valve operation unit 72b, a second branch valve operation unit 72c, and a switching operation unit 72d. The operation unit 372 of this embodiment further has a turbine operation unit 72e.

[0118] (Turbine control section) The turbine control unit 72e operates the turbine 342 to adjust the opening area of ​​the airflow path within the turbine 342.

[0119] (Control method for fuel cell systems) Next, a control method for the fuel cell system 310 according to this embodiment will be described.

[0120] (Control method during fuel cell startup) First, the control method for starting up the fuel cell 20 will be explained with reference to the flow chart in Figure 11. First, the first branch valve operating unit 72b opens the first branch valve 50 (step S311). Next, the turbine operating unit 72e operates the turbine 342 to reduce the opening area of ​​the flow path inside the turbine 342 (step S312). In step S312, the turbine operating unit 72e narrows the distance between the multiple movable vanes installed inside the turbine 342, thereby narrowing the flow path inside the turbine 342 through which the air introduced from the air discharge line L32 passes.

[0121] Subsequently, with the first branch valve 50 open, the electric compressor operating unit 72a starts the electric motor 43 and drives the electric compressor 41a (step S313). At this time, because the first branch valve 50 is open, air is supplied to the electric compressor 41a through the first branch line L35 without any energy loss. Also, when the electric compressor 41a is driven, a flow toward the fuel cell 20 is created in the air supply line L31, and a flow of air discharged from the fuel cell 20 is created in the air discharge line L32. The turbine 342 is driven by the air flowing through the air discharge line L32. The driving force of the turbine 342 is transmitted to the turbine-driven compressor 41b, which drives the turbine-driven compressor 41b. When the turbine-driven compressor 41b is driven, the pressure downstream of the turbine-driven compressor 41b increases. As a result, a backflow occurs in the first branch line L35.

[0122] After step S313, the backflow determination unit 73a determines whether or not backflow has been detected in the first branch line L35 (step S314). The method for detecting backflow in the first branch line L35 can be selected as appropriate. For example, backflow in the first branch line L35 may be detected by measuring the pressure on the downstream and upstream sides of the turbine-driven compressor 41b in the air supply line L31. Alternatively, backflow may be detected from the change in rotational speed of the turbine-driven compressor 41b. If backflow is detected in the first branch line L35 (step S314; YES), the first branch valve operation unit 72b closes the first branch valve 50 (step S315). Subsequently, the turbine operation unit 72e adjusts the opening area of ​​the flow path in the turbine 342 according to the amount of inflow into the turbine 342 (step S316). In step S316, the spacing between the multiple movable vanes installed in the turbine 342 is adjusted, thereby adjusting the opening area of ​​the flow path inside the turbine 342 through which the air introduced from the air exhaust channel passes to an area optimal for driving the turbine 342.

[0123] By following the above procedure, the electric compressor 41a and the turbine-driven compressor 41b are driven. This supplies air to the fuel cell 20, and the fuel cell 20 starts up.

[0124] (Control method when fuel cell output decreases) Furthermore, the control device 370 needs to control the output of the fuel cell 20 according to the load on the drive unit 11. Below, a control method for when the output of the fuel cell 20 decreases will be explained with reference to the flowchart in Figure 12.

[0125] For example, when the load on the drive unit 11 decreases, the inverter 12 sends a signal to the control unit to reduce the output of the fuel cell 20. First, the acquisition unit 71 acquires this signal to reduce the output of the fuel cell 20 (step S321).

[0126] After step S321, the switching operation unit 72d operates the switching unit 49 to increase the amount of air introduced into the bypass line L34 (step S322). In step S322, the completely closed bypass line L34 may be opened to start air flow in the bypass line L34, or the amount of air introduced into the bypass line L34 may be increased by increasing the opening of the bypass line L34, which was originally open. Step S322 increases the airflow rate supplied to the turbine 342 without passing through the fuel cell 20. At this time, the electric compressor operation unit 72a does not arbitrarily reduce the rotational speed of the electric compressor 41a. As the amount of air introduced into the bypass line L34 increases, the pressure downstream of the electric compressor 41a decreases. Subsequently, the turbine operation unit 72e maintains the opening area of ​​the flow path in the turbine 342 to an area optimal for driving the turbine 342, according to the amount of air flowing into the turbine 342 (step S323).

[0127] After step S323, the pressure determination unit 73b determines whether the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to a predetermined pressure (step S324). The predetermined pressure is such that, when the second branch valve 51 is open, air does not flow back from the downstream side to the upstream side of the electric compressor 41a through the second branch line L36. If the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to the predetermined pressure (step S324; YES), the second branch valve operation unit 72c opens the second branch valve 51 (step S325).

[0128] After step S325, the control unit 372 rotates the electric compressor 41a at a speed that does not stop it (step S326).

[0129] After step S326, the load on the drive unit 11 increases again, and when the airflow rate required for the fuel cell 20 exceeds the current airflow rate supplied to the fuel cell 20, the inverter 12 sends a signal to the control device 370 to increase the output of the fuel cell 20. The acquisition unit 71 then acquires this signal to increase the output of the fuel cell 20 (step S327).

[0130] When a signal is received to increase the output of the fuel cell 20, the control unit 372 increases the rotational speed of the electric compressor 41a (step S328).

[0131] In this way, when the output of the fuel cell 20 decreases, the air flow rate to the fuel cell 20 is adjusted. If the load on the drive unit 11 does not increase again, steps S327 to S328 are omitted.

[0132] The control method for the fuel cell 20 before startup is performed using the same procedure as in the first embodiment.

[0133] (Effects and Benefits) The fuel cell system 310 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 310 of this embodiment can achieve the following effects and advantages.

[0134] In this embodiment, the turbine 342 is a variable geometry turbine whose opening area of ​​the flow path through which air introduced from the air discharge line L32 passes can be adjusted. With this configuration, the fuel cell system 310 can adjust the power of the turbine 342 through the turbine 342's own functions. Therefore, it is not necessary to provide the flow rate adjustment line L33 or wastegate valve mentioned above in order to adjust the power of the turbine 342. In addition, the fuel cell system 310 can adjust the pressure inside the fuel cell 20 by adjusting the opening area of ​​the flow path within the turbine 342.

[0135] <Fifth Embodiment> Hereinafter, a fuel cell system 410 according to the fifth embodiment of this disclosure will be described with reference to Figures 13 and 14. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 410 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0136] As shown in Figure 13, the fuel cell system 410 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 440, a cooling system 60, and a control device 70. The air system 440 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, and a switching unit 49.

[0137] In this embodiment, only one compressor 41 is provided in the air supply line L31. This single compressor 41 is an electric compressor 41a driven by an electric motor 43. The electric compressor 41a in this embodiment is connected to a turbine 42 and its drive is assisted by the turbine 42. In other words, in this embodiment, the electric compressor 41a is also a turbine-driven compressor 41b.

[0138] (Control method for fuel cell systems) Next, a control method for the fuel cell system 410 according to this embodiment will be described.

[0139] (Control method when fuel cell output decreases) The control method for when the output of the fuel cell 20 decreases will be explained below with reference to the flow chart in Figure 14.

[0140] For example, when the load on the drive unit 11 decreases, the inverter 12 sends a signal to the control unit to reduce the output of the fuel cell 20. First, the acquisition unit 71 acquires this signal to reduce the output of the fuel cell 20 (step S421).

[0141] After step S421, the switching operation unit 72d operates the switching unit 49 to increase the amount of air introduced into the bypass line L34 (step S422). In step S422, the completely closed bypass line L34 may be opened to start air flow in the bypass line L34, or the amount of air introduced into the bypass line L34 may be increased by increasing the opening of the bypass line L34, which was originally open. Step S422 increases the airflow rate supplied to the turbine 42 without passing through the fuel cell 20. At this time, the electric compressor operation unit 72a does not perform an operation to arbitrarily reduce the rotational speed of the electric compressor 41a. As the amount of air introduced into the bypass line L34 increases, the pressure downstream of the electric compressor 41a decreases.

[0142] After step S422, the pressure determination unit 73b determines whether the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to a predetermined pressure (step S423). The predetermined pressure is such that, when the second branch valve 51 is open, air does not flow back from the downstream side to the upstream side of the electric compressor 41a through the second branch line L36. If the pressure downstream of the electric compressor 41a in the air supply line L31 has dropped to the predetermined pressure (step S423; YES), the electric compressor operation unit 72a rotates the electric compressor 41a at a rotational speed that does not stop it (step S424). At this time, air without energy loss flows into the turbine 42, which has been guided to the turbine 42 through the bypass line L34 without passing through the fuel cell 20.

[0143] After step S424, the load on the drive unit 11 increases again, and when the airflow rate required for the fuel cell 20 exceeds the current airflow rate supplied to the fuel cell 20, the inverter 12 sends a signal to the control device 70 to increase the output of the fuel cell 20. The acquisition unit 71 then acquires this signal to increase the output of the fuel cell 20 (step S425).

[0144] When a signal is received to increase the output of the fuel cell 20, the switching operation unit 72d operates the switching unit 49 to increase the flow rate of air supplied from the electric compressor 41a to the fuel cell 20 (step S426).

[0145] In this way, when the output of the fuel cell 20 decreases, the air flow rate to the fuel cell 20 is adjusted. If the load on the drive unit 11 does not increase again, steps S425 to S426 are omitted.

[0146] The control method for the fuel cell 20 before startup is performed using the same procedure as in the first embodiment.

[0147] (Effects and Benefits) The fuel cell system 410 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 410 of this embodiment can achieve the following effects and advantages.

[0148] In this embodiment, the electric compressor 41a is a turbine-driven compressor 41b connected to the turbine 42.

[0149] With this configuration, one compressor 41 can function as both an electric compressor 41a and a turbine-driven compressor 41b, utilizing the airflow rate from the fuel cell 20. Therefore, the fuel cell system 410 can be made smaller compared to the case where the electric compressor 41a and the turbine-driven compressor 41b are provided separately.

[0150] <Sixth Embodiment> Hereinafter, a fuel cell system 510 according to the sixth embodiment of this disclosure will be described with reference to Figure 15. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 510 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0151] As shown in Figure 15, the fuel cell system 510 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 540, and a cooling system 60. The air system 540 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, a switching unit 49, a first branch line L35, a first branch valve 50, a second branch line L36, and a second branch valve 51. The air system 540 in this embodiment further comprises an air-cooling line L37 and an air-cooling valve 54.

[0152] (Air-cooled line) The air cooling line L37 is a pipe that leads air to the radiator 61. In this embodiment, the air cooling line L37 leads the air flowing through the air system 540 to the radiator 61. More specifically, the air cooling line L37 leads the air flowing in the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a to the radiator 61. The air cooling line L37 connects the portion of the air supply line L31 between the downstream end of the first branch line L35 and the upstream end of the second branch line L36 to the radiator 61.

[0153] (Air-cooled valve) The air-cooling valve 54 is provided to open and close the air-cooling line L37.

[0154] The fuel cell system 510 according to this embodiment is controlled in the same manner as in the first embodiment. In this embodiment, for example, the control method for starting up the fuel cell 20, the control method for when the output of the fuel cell 20 decreases, and the control method for before starting up the fuel cell 20 are executed in the same manner as in the first embodiment.

[0155] (Effects and Benefits) The fuel cell system 510 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 510 of this embodiment can achieve the following effects and advantages.

[0156] In this embodiment, the fuel cell system 510 includes an air cooling line L37 that guides air to the radiator 61. The air cooling line L37 guides the air flowing in the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a to the radiator 61.

[0157] As a result, the fuel cell system 510 can supply air to the radiator 61 that has been compressed by a turbine-driven compressor 41b powered by the air flowing through the air exhaust line L32. Therefore, the power required for the fan 62 that blows air to the radiator 61, and the radiator 61 itself, can be reduced. The fuel cell system 510 can also supply air flowing through the air supply line L31 to the radiator 61. Here, the amount of air supplied to the fuel cell 20 increases or decreases in accordance with the increase or decrease in the output of the fuel cell 20. Therefore, the airflow rate from the air supply line L31 to the radiator 61 through the air cooling line L37 also increases or decreases in accordance with the increase or decrease in the output of the fuel cell 20. However, the airflow rate to the radiator 61 also increases or decreases in accordance with the increase or decrease in the output of the fuel cell 20. Therefore, for example, when the output of the fuel cell 20 increases, it is not necessary to significantly increase the amount of air supplied to the radiator 61.

[0158] <Seventh Embodiment> Hereinafter, a fuel cell system 610 according to the seventh embodiment of this disclosure will be described with reference to Figure 16. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 610 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0159] As shown in Figure 16, the fuel cell system 610 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 640, a cooling system 60, and a control device 70. The air system 640 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, a switching unit 49, and an air-cooling line L37.

[0160] In this embodiment, the air cooling line L37 is a separate pipe from the air supply line L31 and the air discharge line L32. The air cooling line L37 guides air from outside the fuel cell system 610 to the radiator 61. The electric compressor 41a is provided in the air supply line L31, and the turbine-driven compressor 41b is provided in the air cooling line L37. Therefore, the air cooling line L37 can guide air pressurized by the turbine-driven compressor 41b.

[0161] The fuel cell system 610 according to this embodiment is controlled in the same manner as in the first embodiment. In this embodiment, for example, the control method for when the output of the fuel cell 20 decreases and the control method for before starting up the fuel cell 20 are executed in the same manner as in the first embodiment.

[0162] (Effects and Benefits) The fuel cell system 610 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 610 of this embodiment can achieve the following effects and advantages.

[0163] In this embodiment, the turbine-driven compressor 41b is located in the air-cooling line L37. The air-cooling line L37 guides the air pumped by the turbine-driven compressor 41b to the radiator 61.

[0164] As a result, the fuel cell system 610 can supply air to the radiator 61 that has been compressed by a turbine-driven compressor 41b powered by the air flowing through the air exhaust line L32. Therefore, the power required for the fan 62 that blows air to the radiator 61, as well as the radiator 61 itself, can be reduced. Furthermore, the fuel cell system 610 can supply air pressurized by the turbine-driven compressor 41b to the radiator 61 through a flow path independent of the air supply line L31 and the air discharge line L32. Therefore, cooling air can be supplied to the radiator 61 without changing the flow rates of the air supply line L31 and the air discharge line L32.

[0165] <Eighth Embodiment> Hereinafter, a fuel cell system 710 according to the eighth embodiment of this disclosure will be described with reference to Figure 17. Configurations common to the embodiments described above will be given the same names and reference numerals, and their descriptions will be omitted as appropriate. The fuel cell system 710 of this embodiment, like the first embodiment, is mounted on, for example, a cargo handling machine 1 (see Figure 1).

[0166] As shown in Figure 17, the fuel cell system 710 comprises a fuel cell 20, a drive unit 11, a power line L11, an inverter 12, a controller 13, a hydrogen system 30, an air system 740, a cooling system 60, and a control device 70. The air system 740 comprises an air supply line L31, an air discharge line L32, a compressor 41, a turbine 42, an electric motor 43, a heat exchanger 44, an intercooler 45, a second humidifier 46, a second gas-liquid separator 47, a flow rate adjustment line L33, a flow rate adjustment valve 48, a bypass line L34, a switching unit 49, a first branch line L35, a first branch valve 50, a second branch line L36, a second branch valve 51, and an air-cooling line L37.

[0167] In this embodiment, the air cooling line L37 guides the air flowing through the air system 740 to the radiator 61. More specifically, the air cooling line L37 guides the air flowing through the portion of the air discharge line L32 downstream of the turbine 42 to the radiator 61. The downstream end of the flow rate adjustment line L33 is also connected to the air cooling line L37.

[0168] The fuel cell system 710 according to this embodiment is controlled in the same manner as in the first embodiment. In this embodiment, for example, the control method for starting up the fuel cell 20, the control method for when the output of the fuel cell 20 decreases, and the control method for before starting up the fuel cell 20 are executed in the same manner as in the first embodiment.

[0169] (Effects and Benefits) The fuel cell system 710 of this embodiment, with the same configuration as the embodiment described above, can achieve the same effects and advantages as the embodiment described above. Furthermore, the fuel cell system 710 of this embodiment can achieve the following effects and advantages.

[0170] In this embodiment, the air cooling line L37 guides the air flowing in the portion of the air discharge line L32 downstream of the turbine 42 to the radiator 61.

[0171] As a result, the fuel cell system 710 can supply air to the radiator 61 that has been compressed by a turbine-driven compressor 41b powered by the air flowing through the air exhaust line L32. Therefore, the power required for the fan 62 that blows air to the radiator 61, as well as the radiator 61 itself, can be reduced. Furthermore, the fuel cell system 710 can supply the radiator 61 with air that has been expanded and cooled by the turbine 42. This further improves the cooling capacity of the radiator 61.

[0172] <Hardware Configuration> The control devices 70 and 370 of the above embodiments and modified examples are implemented in the computer 1100 shown in Figure 18. Figure 18 is a schematic block diagram showing the configuration of the computer 1100 according to each embodiment. The computer 1100 includes a processor 1110, main memory 1120, storage 1130, and interface 1140.

[0173] The operation of each of the above-mentioned functional units of the control devices 70 and 370 is stored in the storage 1130 in the form of a program. The processor 1110 reads the program from the storage 1130, loads it into the main memory 1120, and executes the above-mentioned processes according to the program. The processor 1110 also allocates storage space in the main memory 1120 according to the program.

[0174] The program may be for the purpose of realizing some of the functions that the computer 1100 is to perform. For example, the program may perform functions in combination with other programs already stored in the storage 1130, or in combination with other programs implemented in other devices. In addition, the computer 1100 may be equipped with a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor 1110 may be realized by the integrated circuit.

[0175] Examples of storage 1130 include magnetic disks, magneto-optical disks, and semiconductor memory. Storage 1130 may be an internal medium directly connected to the bus of computer 1100, or an external medium connected to computer 1100 via interface 1140 or a communication line. Furthermore, if this program is distributed to computer 1100 via a communication line, computer 1100 that receives the program may expand it into main memory 1120 and execute the above processing. Storage 1130 may also be a tangible storage medium that is not temporary.

[0176] Furthermore, the program may be intended to implement some of the functions described above. In addition, the program may be a so-called differential file (differential program) that implements the functions described above in combination with other programs already stored in the storage 1130.

[0177] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes design changes and the like that do not depart from the gist of this disclosure. For example, the above embodiments describe the case in which a heat exchanger 44 is provided in the fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710, but are not limited to this. A heat exchanger 44 may not be provided in the fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710.

[0178] In the above embodiment, the fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710 are mounted on a cargo handling machine 1 (RTG crane), but the embodiment is not limited to this. The fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710 may also be mounted on other electric motors.

[0179] In the above embodiment, the switching section 49 is a three-way valve provided at the connection point between the air supply line L31 and the bypass line L34, but it is not limited to this. The switching section 49 may consist of, for example, a valve provided in the bypass line L34 and a valve provided downstream of the bypass line L34 in the air supply line L31.

[0180] <Note> The fuel cell systems 10, 110, 210, 310, 410, 510, 610, 710 and the cargo handling machine 1 described in each embodiment can be understood, for example, as follows.

[0181] (1) The fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710 of the first embodiment include a fuel cell 20, a drive unit 11 driven by the power generated by the fuel cell 20, an air supply line L31 that supplies air to the fuel cell 20, an air discharge line L32 that discharges air from the fuel cell 20, an electric compressor 41a provided in the air supply line L31 that can pump air towards the fuel cell 20, and a turbine 42 provided in the air discharge line L32 and driven by the air flowing through the air discharge line L32. The system includes 342, a turbine-driven compressor 41b connected to the turbines 42 and 342 and driveable by the turbines 42 and 342, a bypass line L34 connecting the air supply line L31 and the portion of the air discharge line L32 upstream of the turbines 42 and 342, a switching unit 49 capable of introducing at least a portion of the air pumped toward the fuel cell 20 into the bypass line L34, and control devices 70 and 370 that control the switching unit 49 so as to increase the amount of air introduced into the bypass line L34 when the load on the drive unit 11 decreases.

[0182] As a result, fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710 can utilize the air discharged from the fuel cell 20 as power for turbines 42 and 342. When the load on the drive unit 11 decreases, causing a decrease in the output of the fuel cell 20, the control devices 70 and 370 control the switching unit 49 to increase the amount of air introduced into the bypass line L34. As a result, fuel cell systems 10, 110, 210, 310, 410, 510, 610, and 710 can reduce the amount of air supplied to the fuel cell 20 without reducing the rotational speed of the electric compressor 41a. Therefore, it is no longer necessary to change the rotational speed of the electric compressor 41a in response to a decrease in the output of the fuel cell 20, and control is simplified.

[0183] (2) The fuel cell systems 10, 110, 210, 310, 510, 710 of the second embodiment are the fuel cell systems 10, 110, 210, 310, 510, 710 of (1), wherein the turbine-driven compressor 41b may be provided in the portion of the air supply line L31 upstream of the electric compressor 41a.

[0184] As a result, fuel cell systems 10, 110, 210, 310, 510, and 710 can gradually increase the pressure of air using an electric compressor 41a and a turbine-driven compressor 41b connected in series. Furthermore, because the turbine-driven compressor 41b is positioned upstream of the electric compressor 41a, the air flow rate can be secured by the turbine-driven compressor 41b, and then the air pressure can be secured by the electric compressor 41a.

[0185] (3) The third embodiment of the fuel cell systems 10, 110, 210, 310, 510, 710 is the fuel cell systems 10, 110, 210, 310, 510, 710 of (2), further comprising a first branch line L35 connecting the portion of the air supply line L31 upstream of the turbine-driven compressor 41b to the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a, and a first branch valve 50 capable of opening and closing the first branch line L35.

[0186] With this configuration, the fuel cell systems 10, 110, 210, 310, 510, and 710 can introduce air to the electric compressor 41a without passing it through the turbine-driven compressor 41b by opening the first branch valve 50 when the fuel cell 20 is started. Subsequently, if a backflow is detected in the first branch line L35, the first branch valve 50 is closed, allowing the fuel cell systems 10, 110, 210, 310, 510, and 710 to stably drive the turbine-driven compressor 41b.

[0187] (4) The fuel cell systems 10, 110, 310, 510, 710 of the fourth embodiment are the fuel cell systems 10, 110, 310, 410, 510, 610, 710 of (2) or (3), wherein the bypass line L34 connects the portion of the air supply line L31 between the fuel cell 20 and the electric compressor 41a and the portion of the air discharge line L32 upstream of the turbines 42, 342.

[0188] As a result, the air that has been pumped by the electric compressor 41a is introduced into the bypass line L34. Therefore, compared to the case where the bypass line L34 is located upstream of the electric compressor 41a, the fuel cell systems 10, 110, 310, 410, 510, 610, and 710 can introduce more air into the bypass line L34.

[0189] (5) The fuel cell systems 10, 110, 310, 510, 710 of the fifth embodiment are the fuel cell systems 10, 110, 310, 510, 710 of (4), wherein the control devices 70, 370 may control the switching unit 49 and the electric compressor 41a to drive the electric compressor 41a in a state where the switching unit 49 is operated before the start of the fuel cell 20 so that all of the air pumped by the electric compressor 41a is introduced into the bypass line L34.

[0190] As a result, the fuel cell systems 10, 110, 310, 510, and 710 are maintained with only the air systems 40, 140, 340, 540, and 740 operating before the fuel cell 20 is started, and air can be supplied to the fuel cell 20 immediately when it is time to start it.

[0191] (6) A fuel cell system 110 according to a sixth embodiment is the fuel cell system 110 of (2) or (3), which may further include an assist electric motor 52 that assists the turbine-driven compressor 41b.

[0192] This allows control of the rotational speed setting of the turbine-driven compressor 41b by controlling the assist electric motor 52.

[0193] (7) The fuel cell system 210 of the seventh embodiment is the fuel cell system 210 of (2) or (3), wherein the bypass line L34 connects the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a and the portion of the air discharge line L32 upstream of the turbine 42.

[0194] As a result, air is introduced into the bypass line L34 without passing through the electric compressor 41a. Therefore, when the bypass line L34 is in use, air with low pressure loss flows into the turbines 42 and 342.

[0195] (8) The eighth embodiment of the fuel cell system 310 is any one of the fuel cell systems 310 of (1) to (5), wherein the turbine 342 is a variable geometry turbine that can adjust the opening area of ​​the flow path through which air introduced from the air discharge line L32 passes.

[0196] With this configuration, the fuel cell system 310 can adjust the power of the turbine 342 through the turbine 342's own functions. In addition, the fuel cell system 310 can adjust the pressure inside the fuel cell 20 by adjusting the opening area of ​​the flow path within the turbine 342.

[0197] (9) The fuel cell system 410 of the ninth embodiment is the fuel cell system 410 of (1), wherein the electric compressor 41a may be the turbine-driven compressor 41b connected to the turbine 42.

[0198] With this configuration, one compressor 41 can function as both an electric compressor 41a and a turbine-driven compressor 41b, making use of the airflow rate from the fuel cell 20.

[0199] (10) A fuel cell system 510 according to a tenth embodiment is any one of the fuel cell systems 510 of (2) to (4), comprising: a cooling line L41 through which a refrigerant for cooling the fuel cell 20 flows; a radiator 61 for cooling the refrigerant by exchanging heat between the refrigerant and outside air; and an air cooling line L37 for leading air to the radiator 61, wherein the air cooling line L37 may lead air flowing in the portion of the air supply line L31 between the turbine-driven compressor 41b and the electric compressor 41a to the radiator 61.

[0200] As a result, the fuel cell system 510 can supply air to the radiator 61 that has been pressurized by a turbine-driven compressor 41b powered by air flowing through the air discharge line L32. Alternatively, the fuel cell system 510 can supply air flowing through the air supply line L31 to the radiator 61.

[0201] (11) The eleventh embodiment of the fuel cell system 610 is the fuel cell system 610 of (1), comprising: a cooling line L41 through which a refrigerant for cooling the fuel cell 20 flows; a radiator 61 for cooling the refrigerant by exchanging heat between the refrigerant and outside air; and an air cooling line L37 for leading air to the radiator 61, wherein the turbine-driven compressor 41b is provided in the air cooling line L37, and the air cooling line L37 may lead the air pressurized by the turbine-driven compressor 41b to the radiator 61.

[0202] As a result, the fuel cell system 610 can supply air to the radiator 61 that has been pressurized by a turbine-driven compressor 41b powered by the air flowing through the air discharge line L32. In addition, the fuel cell system 610 can supply air pressurized by the turbine-driven compressor 41b to the radiator 61 from a flow path independent of the air supply line L31 and the air discharge line L32.

[0203] (12) A fuel cell system 710 according to a twelfth embodiment is any one of the fuel cell systems 710s from (1) to (5), comprising: a cooling line L41 through which a refrigerant for cooling the fuel cell 20 flows; a radiator 61 for cooling the refrigerant by exchanging heat between the refrigerant and outside air; and an air cooling line L37 for leading air to the radiator 61, wherein the air cooling line L37 may lead air flowing in the portion of the air discharge line L32 downstream of the turbine 42 to the radiator 61.

[0204] As a result, the fuel cell system 710 can supply air to the radiator 61 that has been compressed by a turbine-driven compressor 41b powered by air flowing through the air exhaust line L32. In addition, the fuel cell system 710 can supply air that has been expanded by the turbine 42 and whose temperature has been lowered to the radiator 61.

[0205] (13) The fuel cell systems 10, 110, 210, 310, 510, and 710 of the 13th embodiment include a fuel cell 20, a drive unit 11 driven by the power generated by the fuel cell 20, an air supply line L31 that supplies air to the fuel cell 20, an air discharge line L32 that discharges air from the fuel cell 20, an electric compressor 41a provided in the air supply line L31 that can pump air towards the fuel cell 20, and turbines 42 and 342 provided in the air discharge line L32 that are driven by the air flowing through the air discharge line L32. The system includes a turbine 42, 342-driven compressor 41, which is provided in the air supply line L31 upstream of the electric compressor 41a and connected to the turbines 42, 342, and is driveable by the turbines 42, 342; a first branch line L35 connecting the portion of the air supply line L31 upstream of the turbine 42, 342-driven compressor 41 to the portion of the air supply line L31 between the turbine 42, 342-driven compressor 41 and the electric compressor 41a; and a first branch valve 50 that can open and close the first branch line L35.

[0206] (14) A fourteenth embodiment of a fuel cell system 10, 110, 210, 310, 410, 510, 610, 710 is any one of the fuel cell systems 10, 110, 210, 310, 410, 510, 610, 710 of (1) to (13), comprising a fuel cell system 10, 110, 210, 310, 410, 510, 610, 710, a gantry frame 2, wheels 3 supporting the frame 2, and a crane 4 attached to the frame 2, wherein at least one of the wheels 3 and the crane 4 is driven by the drive unit 11. [Explanation of Symbols]

[0207] 1. Material handling machinery 2 frames 2a Legs 2b Post 2c beam part 3 wheels 4 Cranes 4a Base 4b Wire 4c hook part 10 Fuel cell systems 20 Fuel Cell 21 Anodes 22 Cathode 11 Drive unit 12 Inverters 13 Controllers 30 Hydrogen-based 31 Injectors 32 1st humidifier 33 1st gas-liquid separator 34 Hydrogen circulation pump 40 Air System 41 Compressor 41a Electric Compressor 41b Turbine-driven compressor 42 Turbine 43 Electric motor 44 Heat exchanger 45 Intercooler 46 Second humidifier 47 Second gas-liquid separator 48 Flow control valve 49 Switching unit 50 First branch valve 51 Second branch valve 52 Assist electric motor 54 Air-cooling valve 60 Cooling system 61 Radiator 62 Fan 63 Pump 64 Refrigerant regulating valve 70 Control device 71 Acquisition unit 72 Operation unit 72a Electric compressor operation unit 72b First branch valve operation unit 72c Second branch valve operation unit 72d Switching operation unit 72e Turbine operation unit 73 Judgment unit 73a Reverse flow judgment unit 73b Pressure judgment unit 110 Fuel cell system 140 Air system 210 Fuel cell system 240 Air system 310 Fuel cell system 340 Air system 342 Turbine 370 Control device 372 Operation unit 410 Fuel cell system 440 Air system 510 Fuel cell system 540 Air system 610 Fuel cell system 640 Air system 710 Fuel cell system 740 Air system 1100 Computer 1110 Processor 1120 Main memory 1130 Storage 1140 Interface L11 Power line L21 Hydrogen supply line L22 Hydrogen Emission Line L31 Air supply line L32 Air Exhaust Line L33 Flow rate adjustment line L34 Bypass Line L35 First Branch Line L36 Second Branch Line L37 Air-Cooled Line L41 Cooling Line L42 Refrigerant Supply Line L43 Refrigerant return line M Cargo

Claims

1. Fuel cells and A drive unit driven by the electricity generated by the fuel cell, An air supply line that supplies air to the fuel cell, An air discharge line for discharging air from the fuel cell, An electric compressor provided in the air supply line and capable of pressurizing and supplying air toward the fuel cell, A turbine is provided in the aforementioned air discharge line and is driven by the air flowing through the aforementioned air discharge line, A turbine-driven compressor connected to the turbine and driveable by the turbine, A bypass line connecting the air supply line and the portion of the air discharge line upstream of the turbine, A switching unit that can introduce at least a portion of the air being pumped towards the fuel cell into the bypass line, A control device that controls the switching unit so that the amount of air introduced into the bypass line increases when the load on the drive unit decreases, A fuel cell system equipped with the following features.

2. The turbine-driven compressor is located upstream of the electric compressor in the air supply line. A fuel cell system according to claim 1, including the above.

3. A first branch line connecting the portion of the air supply line upstream of the turbine-driven compressor and the portion of the air supply line between the turbine-driven compressor and the electric compressor, A first branch valve capable of opening and closing the first branch line, The fuel cell system according to claim 2, further comprising:

4. The fuel cell system according to claim 2 or 3, wherein the bypass line connects the portion of the air supply line between the fuel cell and the electric compressor and the portion of the air discharge line upstream of the turbine.

5. The fuel cell system according to claim 4, wherein the control device controls the switching unit and the electric compressor so that, before starting the fuel cell, the switching unit is operated so that all of the air pumped by the electric compressor is introduced into the bypass line, and then drives the electric compressor.

6. The fuel cell system according to claim 2 or 3, further comprising an assist electric motor for assisting the turbine-driven compressor.

7. The fuel cell system according to claim 2 or 3, wherein the bypass line connects the portion of the air supply line between the turbine-driven compressor and the electric compressor and the portion of the air discharge line upstream of the turbine.

8. The fuel cell system according to any one of claims 1 to 3, wherein the turbine is a variable geometry turbine capable of adjusting the opening area of ​​the flow path through which air introduced from the air discharge line passes.

9. The fuel cell system according to claim 1, wherein the electric compressor is a turbine-driven compressor connected to the turbine.

10. A cooling line through which a refrigerant for cooling the fuel cell flows, A radiator that performs heat exchange between the refrigerant and the outside air to cool the refrigerant, An air cooling line that guides air to the aforementioned radiator, Equipped with, The fuel cell system according to claim 2 or 3, wherein the air cooling line guides the air flowing in the portion of the air supply line between the turbine-driven compressor and the electric compressor to the radiator.

11. A cooling line through which a refrigerant for cooling the fuel cell flows, A radiator that performs heat exchange between the refrigerant and the outside air to cool the refrigerant, An air cooling line that guides air to the aforementioned radiator, Equipped with, The turbine-driven compressor is provided in the air cooling line, The fuel cell system according to claim 1, wherein the air cooling line leads air pressurized by the turbine-driven compressor to the radiator.

12. A cooling line through which a refrigerant for cooling the fuel cell flows, A radiator that performs heat exchange between the refrigerant and the outside air to cool the refrigerant, An air cooling line that guides air to the aforementioned radiator, Equipped with, The fuel cell system according to any one of claims 1 to 3, wherein the air cooling line guides the air flowing in the portion of the air discharge line downstream of the turbine to the radiator.

13. Fuel cells and A drive unit driven by the electricity generated by the fuel cell, An air supply line that supplies air to the fuel cell, An air discharge line for discharging air from the fuel cell, An electric compressor provided in the air supply line and capable of pressurizing and supplying air toward the fuel cell, A turbine is provided in the aforementioned air discharge line and is driven by the air flowing through the aforementioned air discharge line, A turbine-driven compressor is provided in the air supply line upstream of the electric compressor, is connected to the turbine, and is driveable by the turbine. A first branch line connecting the portion of the air supply line upstream of the turbine-driven compressor and the portion of the air supply line between the turbine-driven compressor and the electric compressor, A first branch valve capable of opening and closing the first branch line, A fuel cell system equipped with the following features.

14. A fuel cell system according to claim 1 or 13, A gate-shaped frame, Wheels supporting the aforementioned frame, A crane attached to the aforementioned frame, Equipped with, A material handling machine in which at least one of the wheels and the crane is driven by the drive unit.

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