Hydrogen-powered power system

Abstract

To provide a hydrogen power system capable of effectively preventing deterioration of a hydrogen pump.SOLUTION: A hydrogen power system 10 includes a hydrogen engine 12 which operates with using hydrogen as an energy source, a hydrogen tank 16 for storing liquid hydrogen, and a hydrogen pump 20 which pumps up the liquid hydrogen from the hydrogen tank and outputs the liquid hydrogen to the hydrogen engine side, wherein a part of elements slides in the hydrogen tank, and a controller 70. When it is determined that efficiency of the hydrogen pump is deteriorated, the controller stops driving of the hydrogen pump, and then drives the hydrogen pump again after elapse of prescribed stand-by time tw.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification discloses a hydrogen-powered system having a power device operating with hydrogen as an energy source and a hydrogen tank storing liquid hydrogen.

Background Art

[0002] In recent years, a hydrogen-powered system having a power device operating with hydrogen as an energy source and a hydrogen storage structure is known. For example, a fuel cell vehicle is equipped with a hydrogen-powered system having a fuel cell that generates electricity with hydrogen, a motor that operates with the electricity generated by the fuel cell, and a hydrogen tank. Also, a hydrogen engine vehicle is equipped with a hydrogen-powered system having a hydrogen engine that operates with hydrogen and a hydrogen tank.

[0003] Among such hydrogen-powered systems, there are some that store hydrogen in a liquid state in order to improve the hydrogen storage efficiency. In this case, the hydrogen-powered system has a hydrogen tank that stores liquid hydrogen and a hydrogen pump that pumps up the liquid hydrogen. The hydrogen pump usually has a sliding member that slides inside the hydrogen tank. This sliding member is cooled by the liquid hydrogen during the process in which the hydrogen pump sucks and discharges the liquid hydrogen.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, when the efficiency of the hydrogen pump decreases due to some cause, the sliding member of the hydrogen pump may not be sufficiently cooled, and the temperature of the sliding member may rise. If the driving of the hydrogen pump is continued in this state, the friction of the sliding member increases, which may cause deterioration of the sliding member and, consequently, the hydrogen pump.

[0006] Furthermore, Patent Document 1 discloses a technology that limits the vehicle's speed or notifies the user of a warning when an abnormality is detected in the fuel pump installed in the vehicle. However, the technology in Patent Document 1 cannot prevent the deterioration of the hydrogen pump described above.

[0007] Therefore, we disclose a hydrogen-powered system that can effectively prevent the deterioration of hydrogen pumps. [Means for solving the problem]

[0008] The hydrogen power system disclosed herein comprises a power unit that operates using hydrogen as an energy source, a hydrogen tank for storing liquid hydrogen, a hydrogen pump that pumps the liquid hydrogen from the hydrogen tank and outputs it to the power unit, the hydrogen pump having some elements that slide within the hydrogen tank, and a controller, wherein the controller, when it determines that the efficiency of the hydrogen pump has decreased, stops the operation of the hydrogen pump, and then restarts the hydrogen pump after a predetermined waiting time has elapsed.

[0009] With this configuration, the hydrogen pump is cooled by liquid hydrogen during the pause period. This prevents seizing of the sliding members and effectively prevents deterioration of the hydrogen pump.

[0010] In this case, the hydrogen pump may be a piston pump having a cylinder containing a pump chamber through which the liquid hydrogen flows in and out, and a piston that expands and contracts the pump chamber by sliding back and forth within the cylinder.

[0011] With this configuration, the sliding members, the piston and cylinder, can reliably come into contact with liquid hydrogen, and the piston and cylinder are cooled by the liquid hydrogen.

[0012] The hydrogen power system may further include a vaporizer that vaporizes the pumped liquid hydrogen and converts it into hydrogen gas, and an intermediate chamber that temporarily stores the hydrogen gas output from the vaporizer.

[0013] By incorporating an intermediate chamber, hydrogen can be supplied to the power unit even if the hydrogen pump is temporarily stopped. As a result, the deterioration of the hydrogen pump can be effectively prevented while suppressing a decrease in the efficiency of the hydrogen power system itself.

[0014] Furthermore, the controller determines that the efficiency of the hydrogen pump has decreased if a specified decrease in performance continues for a specified first judgment time. The decrease in performance is a condition that satisfies at least one of the first and second conditions, the first condition being that the amount of drive of the hydrogen pump is equal to or greater than a specified standard drive amount, and the second condition being that the temperature of the liquid hydrogen output from the hydrogen pump is equal to or greater than a specified standard temperature, or the pressure of the liquid hydrogen output from the hydrogen pump is less than a standard pressure.

[0015] This configuration allows for reliable detection of a decrease in the efficiency of the hydrogen pump.

[0016] In this case, if the controller determines that the condition has deteriorated, it may strengthen the output limit of the power unit compared to before the determination, and after the hydrogen pump is restarted, it may gradually relax the output limit of the power unit according to the efficiency status of the hydrogen pump.

[0017] This configuration allows for reducing the load on the hydrogen pump depending on the situation, thereby more effectively preventing the deterioration of the hydrogen pump. [Effects of the Invention]

[0018] According to the technology disclosed herein, if it is determined that the efficiency of the hydrogen pump has decreased, the hydrogen pump is temporarily shut down. During this shutdown period, the hydrogen pump is cooled by liquid hydrogen, thereby effectively preventing deterioration of the hydrogen pump.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram showing the configuration of a hydrogen-powered system. [Figure 2] It is a cross-sectional view showing the configuration at the end of the hydrogen pump. [Figure 3] It is a flowchart showing the first half of the fail-safe process of the hydrogen pump. [Figure 4] It is a flowchart showing the second half of the fail-safe process of the hydrogen pump. [Figure 5] It is a flowchart showing the process flow for determining the presence or absence of efficiency degradation.

Modes for Carrying Out the Invention

[0020] Hereinafter, the configuration of the hydrogen-powered system 10 will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the hydrogen-powered system 10. This hydrogen-powered system 10 stores hydrogen in a liquid state and converts the hydrogen into a gaseous state to supply it to the power device. In this example, the power device is a hydrogen engine 12. This hydrogen-powered system 10 is mounted on a vehicle. The configuration of the hydrogen engine 12 is not particularly limited. Hereinafter, the hydrogen engine 12 is a direct injection type hydrogen engine that directly injects hydrogen gas into the engine cylinder.

[0021] The hydrogen-powered system 10 has a hydrogen tank 16 for storing liquid hydrogen. The hydrogen tank 16 stores liquid hydrogen in a heat-insulated manner. As such a hydrogen tank 16, for example, a double-structured container can be used. In this case, the hydrogen tank 16 has an inner tank 18 and an outer tank 19 that covers the inner tank 18, and a vacuum heat-insulating layer is formed between the inner tank 18 and the outer tank 19.

[0022] In the hydrogen tank 16, the liquid hydrogen is kept at an extremely low temperature (for example, below -253°C). Furthermore, the pressure of the liquid hydrogen in the hydrogen tank 16 is approximately the same as atmospheric pressure, or slightly higher, for example, 1 MPa or less.

[0023] The hydrogen tank 16 is equipped with a hydrogen pump 20 that pumps up the stored liquid hydrogen and sends it to the hydrogen engine 12. This hydrogen pump 20 is a booster pump that discharges liquid hydrogen under pressure. More specifically, the hydrogen pump 20 is a piston pump having a cylinder 22 and a piston 28 (not shown in Figure 1, see Figure 2). The end of the hydrogen pump 20 is located inside the hydrogen tank 16.

[0024] Figure 2 is a schematic cross-sectional view of the end of the hydrogen pump 20. As shown in Figure 2, a pump chamber 26 is formed at the end of the hydrogen pump 20 by a cylinder 22 and a cylinder head 24. The piston 28 moves back and forth within the cylinder 22, thereby expanding and contracting the pump chamber 26. The piston 28 moves back and forth by power output from the pump motor 23 (see Figure 1). Naturally, the circumferential surface of the piston 28 is in close contact with the inner circumferential surface of the cylinder 22, and the piston 28 slides within the cylinder 22.

[0025] As the pump chamber 26 expands, liquid hydrogen in the hydrogen tank 16 is drawn into the pump chamber 26 through the suction port 32. Conversely, as the pump chamber 26 contracts, the liquid hydrogen in the pump chamber 26 is pressurized and then pumped into the liquid flow path 40 through the discharge port 34. To enable this suction and discharge of liquid hydrogen, check valves 36 and 38 are provided at the suction port 32 and the discharge port 34. By providing the hydrogen pump 20 with a pressurizing function in this way, the required pressure resistance of the hydrogen tank 16 can be reduced.

[0026] In other words, as described above, in this example, the hydrogen engine 12 is a direct-injection type that directly injects hydrogen gas into the engine cylinders. The hydrogen gas that is directly injected is required to be at a very high pressure compared to atmospheric pressure (for example, 5 MPa to several tens of MPa). In order to obtain such high-pressure hydrogen gas, it is required that it be at a sufficiently high pressure before vaporization, i.e., in its liquid state. Therefore, it is conceivable to store high-pressure (for example, several tens of MPa) liquid hydrogen in the hydrogen tank 16. However, in this case, the pressure resistance performance of the hydrogen tank 16 must be increased, which would lead to an increase in the cost and weight of the hydrogen tank 16.

[0027] On the other hand, in this example, the pressure of the liquid hydrogen in the hydrogen tank 16 is set to approximately the same as atmospheric pressure or slightly higher, and when vaporizing the liquid hydrogen, only the necessary amount is sufficiently pressurized by the hydrogen pump 20 before being extracted. With this configuration, it is possible to obtain sufficiently high-pressure hydrogen gas while keeping the pressure resistance performance of the hydrogen tank 16 low. Furthermore, by lowering the required pressure resistance performance, the cost of the hydrogen tank 16 can be reduced. In addition, by lowering the required pressure resistance performance, it becomes possible to adopt shapes other than spherical and cylindrical for the hydrogen tank 16, increasing the flexibility of the shape of the hydrogen tank 16.

[0028] Let's refer to Figure 1 again for further explanation. The pressure sensor 44 and temperature sensor 42 detect the pressure and temperature of the liquid hydrogen discharged from the hydrogen pump 20. Hereafter, the pressure detected by the pressure sensor 44 will be referred to as "discharge hydrogen pressure PH," and the temperature detected by the temperature sensor 42 will be referred to as "discharge hydrogen temperature TH." As the efficiency of the hydrogen pump 20 decreases, the discharge hydrogen pressure PH tends to decrease, and the discharge hydrogen temperature TH tends to increase.

[0029] Liquid hydrogen discharged from the hydrogen pump 20 is supplied to the hydrogen engine 12 through the liquid flow path 40 and the gas flow path 46. The liquid flow path 40 is a flow path that guides the liquid hydrogen discharged from the hydrogen pump 20 to the vaporizer 48. The vaporizer 48 is a heat exchanger that converts liquid hydrogen into hydrogen gas by exchanging heat between liquid hydrogen and a refrigerant. The hydrogen gas produced in the vaporizer 48 is output to the gas flow path 46.

[0030] The vaporizer 48 exchanges heat between liquid hydrogen and the refrigerant, vaporizing the liquid hydrogen. The refrigerant pump 52 circulates the refrigerant between the vaporizer 48 and the heat source 50. The refrigerant is not particularly limited and may be a gas such as helium or a liquid such as water.

[0031] The gas flow path 46 is a flow path that guides hydrogen gas from the vaporizer 48 to the injector 14. An intermediate chamber 54 is connected to the gas flow path 46 via an inlet flow path 56 and an outlet flow path 60. The intermediate chamber 54 is located between the hydrogen tank 16 and the hydrogen engine 12 and is a container for temporarily storing hydrogen gas. By storing a certain amount of hydrogen gas in this intermediate chamber 54, even if the pumping of liquid hydrogen by the hydrogen pump 20 is temporarily suppressed or interrupted, hydrogen gas can be stably supplied to the hydrogen engine 12.

[0032] The inflow channel 56 is equipped with a check valve 58 that prevents flow from the intermediate chamber 54 toward the gas channel 46. The outflow channel 60 is equipped with a shut valve 62. The shut valve 62 is generally kept open while the hydrogen engine 12 is running. The inflow channel 56 is located upstream of the outflow channel 60. Therefore, if the pressure in the gas channel 46 is higher than the internal pressure of the intermediate chamber 54, the check valve 58 opens and hydrogen gas flows into the intermediate chamber 54. On the other hand, if the internal pressure of the intermediate chamber 54 is higher than the pressure in the gas channel 46, the hydrogen gas stored in the intermediate chamber 54 is supplied to the gas channel 46 through the outflow channel 60.

[0033] A supply pressure reducing valve 64 is provided downstream of the outflow channel 60. The supply pressure reducing valve 64 reduces the hydrogen gas pressure to a level suitable for the hydrogen engine 12. The reduced-pressure hydrogen gas is supplied to the hydrogen engine 12 via the injector 14. The flow rate of hydrogen gas supplied to the hydrogen engine 12 is detected by a flow meter 66.

[0034] The controller 70 controls the operation of the hydrogen power system 10. Physically, the controller 70 is a computer having a processor 72 and memory 74. This "computer" also includes a microcontroller that incorporates a computer system into a single integrated circuit. Furthermore, the controller 70 is not limited to a single computer, but may be configured by combining multiple physically separated computers. Based on values ​​detected by various sensors, the controller 70 controls the operation of multiple valves and pumps provided in the hydrogen power system 10.

[0035] Specifically, the controller 70 controls the flow rate of hydrogen gas supplied to the hydrogen engine 12 in response to a request from the engine control unit (not shown). The controller 70 also performs fail-safe processing for the hydrogen pump 20. The fail-safe processing for the hydrogen pump 20 will be described in detail below.

[0036] As described above, when the hydrogen pump 20 is driven, some of its elements (specifically the piston 28) undergo sliding motion. The piston 28 and cylinder 22 involved in the sliding motion are normally cooled by the liquid hydrogen flowing into the pump chamber 26. However, if the efficiency of the hydrogen pump 20 decreases for any reason, the piston 28 and cylinder 22 will no longer be sufficiently cooled by the liquid hydrogen. This can reduce the clearance between the piston 28 and cylinder 22, causing their temperatures to rise. If the hydrogen pump 20 continues to operate in this state, the temperatures of the piston 28 and cylinder 22 will rise further, and in some cases, the piston 28 may seize against the cylinder 22, causing the hydrogen pump 20 to deteriorate or break.

[0037] To suppress the deterioration of the hydrogen pump 20, the controller 70 monitors the status of the hydrogen pump 20 and, if necessary, performs a fail-safe procedure to temporarily stop the operation of the hydrogen pump 20. Figures 3 and 4 are flowcharts showing the flow of the fail-safe procedure. This fail-safe procedure is performed repeatedly while the hydrogen engine 12 is running.

[0038] In fail-safe processing, the controller 70 monitors whether the hydrogen pump 20 is in a specified low state. Here, "low state" refers to a state that satisfies both the first and second conditions described below. The first condition is that the drive amount of the hydrogen pump 20 (hereinafter referred to as "pump drive amount DA") is equal to or greater than a specified reference drive amount DAst. As a parameter representing the pump drive amount DA, for example, the most recent power consumption of the hydrogen pump 20 or the most recent number of discharges of the hydrogen pump 20 can be used. The reference drive amount DAst may be a fixed value that does not change regardless of the situation, or it may be a variable value that changes depending on the situation. For example, the reference drive amount DAst may be a variable value that changes according to the target discharge flow rate of the hydrogen pump 20.

[0039] The second condition is that the discharge hydrogen temperature TH is equal to or greater than the specified reference temperature THst, or the discharge hydrogen pressure PH is less than the specified reference pressure PHst. Here, the reference temperature THst and reference pressure PHst may be fixed values ​​that do not change regardless of the situation, or they may be variable values ​​that change depending on the situation.

[0040] When the controller 70 satisfies both the first condition and the second condition, it determines that the hydrogen pump 20 is in a degraded state. Note that FIG. 5 is a flowchart showing the flow of determining whether the hydrogen pump 20 is in a degraded state. As shown in FIG. 5, the controller 70 compares the pump drive amount DA with the reference drive amount DAst (S50). If DA < DAst (No in S50), it determines that it is not in a degraded state (S58). On the other hand, if DA ≥ DAst (Yes in S50), the controller 70 compares the discharged hydrogen temperature TH with the reference temperature THst (S52). As a result of the comparison, if TH ≥ THst (Yes in S52), the controller 70 determines that the hydrogen pump 20 is in a degraded state (S56). On the other hand, if TH < THst (No in S52), the controller 70 compares the discharged hydrogen pressure PH with the reference pressure PHst (S54). As a result of the comparison, if PH ≥ PHst (No in S54), the controller 70 determines that the hydrogen pump 20 is not in a degraded state (S58). On the other hand, if PH < PHst (Yes in S54), the controller 70 determines that the hydrogen pump 20 is in a degraded state (S56).

[0041] Referring again to FIG. 3 for explanation. When the hydrogen pump 20 is not in a degraded state (No in S10), the controller 70 continues to monitor the state of the hydrogen pump 20. On the other hand, when the hydrogen pump 20 is in a degraded state (Yes in S10), the controller 70 strengthens the output limit of the hydrogen engine 12 (S12). That is, normally, an upper limit value, that is, an output limit value, is set for the output value of the hydrogen engine 12. An engine controller (not shown) controls the drive of the hydrogen engine 12 so that the output from the hydrogen engine 12 does not exceed this output limit value. Normally, a predetermined standard limit value LMst is set as this output limit value.

[0042] When the hydrogen pump 20 is in a degraded state, the controller 70 sets the output limit value of the hydrogen engine 12 to a regulated limit value LMa lower than the standard limit value LMst. When the output limit value of the hydrogen engine 12 decreases, the pumping requirement for liquid hydrogen also decreases accordingly, reducing the load on the hydrogen engine 12.

[0043] The controller 70 continues to monitor whether the hydrogen pump 20 is in a reduced state while the load on the hydrogen engine 12 is reduced (S14). If the reduced state of the hydrogen engine 12 is resolved during the monitoring process (No in S14), the controller 70 completely relaxes the output limit of the hydrogen engine 12 (S16). That is, the controller 70 changes the output limit value of the hydrogen engine 12 from the regulated limit value LMa to the standard limit value LMst and then returns to step S10.

[0044] On the other hand, if the hydrogen engine 12 remains in a reduced state (Yes in S14), the controller 70 compares the elapsed time since the reduced state began with a specified first decision time tf (S18). The first decision time tf is not particularly limited, but is, for example, about 2 to 5 seconds. If the reduced state continues for the first decision time tf (Yes in S18), the controller 70 determines that the efficiency of the hydrogen pump 20 has decreased. In this case, the controller 70 stops driving the hydrogen pump 20 (S20). As a result, the sliding motion of the piston 28 of the hydrogen engine 12 stops. During this stop period, the piston 28 and cylinder 22 are cooled by the liquid hydrogen present around them. This increases the clearance between the piston 28 and cylinder 22, and the efficiency of the hydrogen pump 20 is restored.

[0045] If the hydrogen pump 20 stops, the supply of hydrogen from the hydrogen tank 16 to the liquid flow path 40 will naturally be interrupted. However, in this example, since a certain amount of hydrogen gas is stored in the intermediate chamber 54, even if the hydrogen supply from the hydrogen tank 16 is temporarily interrupted, the supply of hydrogen gas to the hydrogen engine 12 can continue. In other words, in this example, during the period when the hydrogen pump 20 is stopped, the hydrogen engine 12 continues to run, albeit with increased power limitations.

[0046] The controller 70 restarts the hydrogen pump 20 after a predetermined waiting time tw has elapsed (S22) after the hydrogen pump 20 has stopped (S24). The waiting time tw is not particularly limited, but for example, it is a value greater than the first decision time tf, for example, 5 to 15 seconds. The waiting time tw may be a fixed value that remains constant regardless of the situation, or it may be a variable value that changes depending on the situation. For example, the waiting time tw may be a variable value that increases as the pump drive amount DA detected immediately before stopping the hydrogen pump 20 is larger, or as the discharge hydrogen temperature TH is higher, or as the discharge hydrogen pressure PH is lower.

[0047] When the hydrogen pump 20 is restarted, the controller 70 gradually eases the output limit of the hydrogen engine 12 (S26-S38 in Figure 4). Specifically, after the hydrogen pump 20 is restarted, the controller 70 detects the state of the hydrogen pump 20 when a predetermined second decision time ts has elapsed (Yes in S26). If the hydrogen pump 20 is in a reduced state at this time (Yes in S28), the controller returns to step S20 (see Figure 3) and stops the hydrogen pump 20 again. The second decision time ts is not particularly limited and can be, for example, 2 to 7 seconds.

[0048] On the other hand, if the hydrogen pump 20 is not in a reduced state in step S28 (No in S28), the controller 70 temporarily relaxes the output limit of the hydrogen engine 12 (S30). In the case of temporary relaxation, the controller 70 sets the output limit to an intermediate limit LMb, which is smaller than the standard limit LMst and larger than the regulated limit LMa.

[0049] Furthermore, the controller 70 continues to drive the hydrogen pump 20 for the second decision time ts with the output limit temporarily relaxed (S32). Then, when the second decision time ts has elapsed (Yes in S32), the controller 70 again determines the state of the hydrogen pump 20 (S34). If the determination shows that the hydrogen pump 20 is in a reduced state (Yes in S34), the controller 70 strengthens the output limit of the hydrogen engine 12 (S36) and returns to step S26. On the other hand, if the controller 70 determines in step S34 that the hydrogen engine 12 is not in a reduced state (No in S34), it completely relaxes the output limit of the hydrogen engine 12 (S38). That is, it changes the output limit value of the hydrogen engine 12 from the intermediate limit value LMb to the standard limit value LMst. After that, the controller 70 repeats the process from steps S10 to S38 until it is instructed to stop the operation of the hydrogen power system 10.

[0050] As is clear from the above explanation, in this example, if the efficiency of the hydrogen engine 12 decreases, the hydrogen pump 20 is temporarily shut off. During this temporary shutdown, the area around the sliding member of the hydrogen pump 20 is cooled by liquid hydrogen, which helps restore the efficiency of the hydrogen pump 20. As a result, deterioration of the hydrogen pump 20 can be effectively prevented.

[0051] Furthermore, in this example, since an intermediate chamber 54 for temporarily storing hydrogen gas is provided, the hydrogen engine 12 can be continuously driven even if it is temporarily stopped. In other words, according to this example, deterioration of the hydrogen pump 20 can be prevented while suppressing a decrease in the efficiency of the hydrogen power system 10.

[0052] Furthermore, in this example, the output limit of the hydrogen engine 12 is changed according to the condition of the hydrogen pump 20. This prevents excessive load on the hydrogen pump 20, thereby more effectively preventing deterioration of the hydrogen pump 20.

[0053] It should be noted that the configurations described above are all examples, and other configurations may be modified as appropriate, as long as the configuration described in claim 1 is met. For example, in the above description, the output limit of the hydrogen engine 12 is changed according to the state of the hydrogen pump 20. However, if the operation of the hydrogen pump 20 is temporarily suspended according to the state of the hydrogen pump 20, the output limit of the hydrogen engine 12 does not need to be changed. Also, the conditions for determining that the efficiency of the hydrogen pump 20 has decreased may be changed as appropriate. For example, in the above description, the controller 70 determines that the efficiency of the hydrogen pump 20 has decreased and temporarily stops the operation of the hydrogen pump 20 if the state in which both the first and second conditions are met continues for a waiting time tw. However, it may also determine that the efficiency of the hydrogen pump 20 has decreased if the state in which only one of the first or second conditions is met continues. Furthermore, the presence or absence of a decrease in the efficiency of the hydrogen pump 20 may be determined based on other conditions.

[0054] Furthermore, the above description uses the hydrogen engine 12 as an example of a power unit. However, the power unit may be any other device that outputs power using hydrogen as an energy source. For example, the power unit may be a device having a fuel cell that generates electricity using hydrogen and a motor that outputs power using the electricity generated by the fuel cell. Also, in the above description, if the efficiency of the hydrogen pump 20 decreases, the operation of the hydrogen pump 20 will be stopped any number of times. However, if the operation of the hydrogen pump 20 stops frequently, the user may be notified of the warning and the operation of the hydrogen power system 10 itself may be stopped. [Explanation of symbols]

[0055] 10 Hydrogen power system, 12 Hydrogen engine, 14 Injector, 16 Hydrogen tank, 18 Inner tank, 19 Outer tank, 20 Hydrogen pump, 22 Cylinder, 23 Pump motor, 24 Cylinder head, 26 Pump chamber, 28 Piston, 32 Suction port, 34 Discharge port, 36, 38, 58 Check valves, 40 Liquid flow path, 42 Temperature sensor, 44 Pressure sensor, 46 Gas flow path, 48 Vaporizer, 50 Heat source, 52 Refrigerant pump, 54 Intermediate chamber, 56 Inflow flow path, 60 Outflow flow path, 62 Shut-off valve, 64 Supply pressure reducing valve, 66 Flow meter, 70 Controller, 72 Processor, 74 Memory.

Claims

1. A power unit that operates using hydrogen as an energy source, A hydrogen tank having an inner tank for storing liquid hydrogen and an outer tank covering the inner tank, A hydrogen pump that draws up the liquid hydrogen from the hydrogen tank and outputs it to the power unit, wherein some elements of the hydrogen pump slide within the hydrogen tank, Controller and The controller, when it determines that the efficiency of the hydrogen pump has decreased, stops the operation of the hydrogen pump, and then restarts the hydrogen pump after a predetermined waiting time has elapsed. A hydrogen-powered system characterized by the following features.

2. A hydrogen power system according to claim 1, The hydrogen pump is a piston pump having a cylinder containing a pump chamber through which the liquid hydrogen flows in and out, and a piston that slides back and forth within the cylinder to expand and contract the pump chamber. A hydrogen-powered system characterized by the following features.

3. A hydrogen power system according to claim 1, further, A vaporizer that vaporizes the pumped liquid hydrogen and converts it into hydrogen gas, An intermediate chamber for temporarily storing the hydrogen gas output from the vaporizer, Equipped with, Even during periods when the hydrogen pump is stopped due to a decrease in its efficiency, hydrogen gas is supplied from the intermediate chamber to the power unit. A hydrogen-powered system characterized by the following features.

4. A hydrogen power system according to claim 1, The controller determines that the efficiency of the hydrogen pump has decreased if the specified decrease in efficiency persists for a specified first judgment time. The aforementioned decrease state is a state that satisfies at least one of the first and second conditions, The first condition is that the amount of drive of the hydrogen pump is equal to or greater than the specified standard amount of drive. The second condition is that the temperature of the liquid hydrogen output from the hydrogen pump is equal to or greater than a specified reference temperature, or the pressure of the liquid hydrogen output from the hydrogen pump is less than a reference pressure. A hydrogen-powered system characterized by the following features.

5. A hydrogen power system according to claim 4, The aforementioned controller, If the aforementioned decrease in power is determined, the output limit of the power unit will be strengthened compared to before the determination. After the hydrogen pump is restarted, the output limit of the power unit is gradually relaxed according to the efficiency status of the hydrogen pump. A hydrogen-powered system characterized by the following features.

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