Vehicle-mounted liquid hydrogen system applied to liquid hydrogen fuel cell locomotive

Abstract

The invention discloses a vehicle-mounted liquid hydrogen system applied to a liquid hydrogen fuel cell locomotive, and relates to the field of rail transit hydrogen energy equipment, a gas phase area of a liquid hydrogen bottle is used for containing BOG gas generated by liquid hydrogen evaporation, and a gas phase outlet provides a channel for discharging the BOG gas; the pressure sensor arranged in the gas phase area can detect the gas pressure in the bottle in real time and transmit signals to the liquid hydrogen system controller, the BOG processing valve comprises at least two BOG switch valves with different calibers and is communicated with the gas phase area in a one-to-one mode, and based on the working principle, the liquid hydrogen system controller can control the liquid hydrogen system according to the pressure change condition fed back by the pressure sensor. When the pressure in the bottle is at a lower level, only the small-caliber BOG switch valve is opened, so that trace precise release of BOG gas is realized, and the waste of hydrogen energy caused by extensive opening of a traditional single large-caliber valve is avoided; the BOG switch valve with a larger caliber is gradually opened along with the increase of the pressure in the bottle, so that the pressure in the bottle is quickly reduced, and the operation safety of the system is improved.

Description

Technical Field

[0001] This application relates to the field of hydrogen energy equipment technology for rail transit, and in particular to an onboard liquid hydrogen system for a liquid hydrogen fuel cell locomotive. Background Technology

[0002] Liquid hydrogen fuel, due to its clean and efficient characteristics, has become an important direction for hydrogen energy applications in the rail transit sector. Rail transit vehicles are equipped with multiple onboard liquid hydrogen systems. Liquid hydrogen needs to be stored in an ultra-low temperature environment of around -253°C. Even with perfect insulation measures, some liquid hydrogen in the onboard liquid hydrogen cylinders will still evaporate due to heat conduction, producing BOG (Boil-Off Gas). If BOG gas is not dealt with in time, it can cause the liquid hydrogen cylinder pressure to exceed the limit, posing a safety risk of explosion.

[0003] In existing technologies, a single large-diameter BOG (Booster Gas) venting valve is typically installed on each liquid hydrogen cylinder. When the pressure in the liquid hydrogen cylinder exceeds the upper limit, the BOG venting valve is opened to release BOG gas. However, this method has significant drawbacks: the release method using a single large-diameter BOG venting valve results in coarse flow control, which can easily lead to a large waste of hydrogen energy.

[0004] Therefore, there is an urgent need for an on-board liquid hydrogen system that can achieve refined emission of BOG gas to improve the utilization rate of hydrogen energy. Summary of the Invention

[0005] In view of the above problems, this application provides an onboard liquid hydrogen system for liquid hydrogen fuel cell vehicles, aiming to achieve refined emission of BOG gas and improve the utilization rate of hydrogen energy. The specific solution is as follows:

[0006] The first aspect of this application provides an onboard liquid hydrogen system for use in a liquid hydrogen fuel cell vehicle, comprising:

[0007] A liquid hydrogen cylinder for storing liquid hydrogen includes a gas phase region and a liquid phase region. The gas phase region is the space occupied by gaseous hydrogen, and the liquid phase region is the space occupied by liquid hydrogen. The gas phase region is provided with a gas phase outlet, and the liquid phase region is provided with a liquid phase outlet.

[0008] A BOG processing valve is installed at the gas phase outlet of the liquid hydrogen cylinder. The BOG processing valve includes at least two BOG switching valves. The different BOG switching valves have different diameters and are connected one-to-one with the gas phase area of ​​the liquid hydrogen cylinder.

[0009] A pressure sensor installed in the gas phase region of the liquid hydrogen cylinder is used to detect the gas pressure in the liquid hydrogen cylinder.

[0010] The liquid hydrogen system controller is used to open the corresponding BOG switching valves in stages, from small diameter to large diameter, based on the pressure changes of the gas pressure.

[0011] In one possible implementation, the BOG processing valves, ordered from smallest to largest caliber, sequentially include a first BOG switch valve, a second BOG switch valve, a third BOG switch valve, a fourth BOG switch valve, a fifth BOG switch valve, a sixth BOG switch valve, a seventh BOG switch valve, and an eighth BOG switch valve.

[0012] In one possible implementation, when the liquid hydrogen system controller opens the corresponding BOG switching valves in stages according to the pressure changes based on the gas pressure, from small diameter to large diameter, it specifically includes:

[0013] If the gas pressure is greater than or equal to the first preset pressure threshold and less than the second preset pressure threshold, the first BOG switch valve and the second BOG switch valve are opened alternately.

[0014] If the gas pressure is greater than or equal to the second preset pressure threshold and less than the third preset pressure threshold, the first BOG switch valve and the second BOG switch valve are controlled to be in the open state, and the third BOG switch valve and the fourth BOG switch valve are alternately opened.

[0015] If the gas pressure is greater than or equal to the third preset pressure threshold and less than the fourth preset pressure threshold, the first BOG switch valve, the second BOG switch valve, the third BOG switch valve and the fourth BOG switch valve are controlled to be in the open state, and the fifth BOG switch valve and the sixth BOG switch valve are alternately opened.

[0016] If the gas pressure is greater than or equal to the fourth preset pressure threshold, the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve, and the sixth BOG switch valve are controlled to be in the open state, and the seventh BOG switch valve and the eighth BOG switch valve are opened.

[0017] One possible implementation also includes:

[0018] The liquid phase outlet valve, located at the liquid phase outlet of the liquid hydrogen cylinder, is used to connect the liquid phase area of ​​the liquid hydrogen cylinder with the external pipeline.

[0019] A main shut-off valve connected to the input end of the liquid phase outlet valve of the liquid hydrogen cylinder is used to supply liquid hydrogen to the external pipeline;

[0020] A vaporizer, whose input end is connected to the output end of the liquid phase outlet valve, is used to provide heat energy to liquid hydrogen so that liquid hydrogen is converted into gaseous hydrogen.

[0021] A first temperature sensor is installed at the output end of the vaporizer to detect the temperature of the gaseous hydrogen output by the vaporizer;

[0022] A pressure reducing valve, whose input is connected to the output of the vaporizer, is used to regulate the output pressure of gaseous hydrogen.

[0023] A hydrogen supply valve is connected to the output of the pressure reducing valve at its input end, and the output of the hydrogen supply valve is connected to the fuel cell system.

[0024] One possible implementation also includes:

[0025] An overcurrent protection valve connected in series between the main shut-off valve and the liquid phase outlet valve is used to detect the flow rate of liquid hydrogen flowing through the overcurrent protection valve.

[0026] In one possible implementation, the liquid hydrogen system controller is connected to the overcurrent protection valve and is used to close the overcurrent protection valve if the liquid hydrogen flow rate is greater than or equal to a preset safety threshold.

[0027] In one possible implementation, the liquid hydrogen system controller is connected to the liquid phase outlet valve, the vaporizer, the first temperature sensor, the pressure reducing valve, the main shut-off valve, and the hydrogen supply valve, respectively.

[0028] The liquid hydrogen system controller is also configured to, if a hydrogen supply command is detected, open the main shut-off valve, the liquid phase outlet valve, the pressure reducing valve, and the hydrogen supply valve; if the temperature detected by the first temperature sensor is not within a preset temperature range, close the liquid phase outlet valve, the pressure reducing valve, and the hydrogen supply valve; if the temperature detected by the first temperature sensor is within the preset temperature range, adjust the opening of the pressure reducing valve to regulate the output pressure of gaseous hydrogen.

[0029] In one possible implementation, it is also used for:

[0030] If a hydrogen supply stop command is detected, the hydrogen supply valve, the liquid phase outlet valve, the pressure reducing valve, and the main shut-off valve are closed.

[0031] One possible implementation also includes:

[0032] A level gauge installed inside the liquid hydrogen cylinder is used to detect the liquid hydrogen level in the liquid hydrogen cylinder;

[0033] A hydrogen filling port, which communicates with the liquid phase region of the liquid hydrogen cylinder, is used to receive liquid hydrogen being filled into the liquid hydrogen cylinder;

[0034] A one-way valve installed on the cap of the liquid hydrogen cylinder allows liquid hydrogen to flow unidirectionally from the hydrogen filling port into the liquid hydrogen cylinder.

[0035] In one possible implementation, the liquid hydrogen system controller is connected to the level gauge, the hydrogen filling port, and the one-way valve, respectively.

[0036] The liquid hydrogen system controller is further configured to: open the one-way valve if a hydrogen addition command is detected, so that liquid hydrogen flows unidirectionally from the hydrogen addition port into the liquid hydrogen cylinder; and close the one-way valve if the liquid level detected by the level gauge reaches a preset liquid level threshold.

[0037] Using the above technical solution, this application provides an on-board liquid hydrogen system for liquid hydrogen fuel cell vehicles. The gas phase region of the liquid hydrogen cylinder is used to contain BOG gas generated by liquid hydrogen evaporation, and the gas phase outlet provides a channel for the discharge of BOG gas. A pressure sensor installed in the gas phase region can detect the gas pressure inside the cylinder in real time and transmit the signal to the liquid hydrogen system controller. The BOG handling valve includes at least two BOG switching valves of different diameters and is connected one-to-one with the gas phase region. Based on this working principle, the liquid hydrogen system controller can open the corresponding BOG switching valves in stages according to the pressure changes fed back by the pressure sensor, in the order from small diameter to large diameter: when the pressure inside the cylinder is at a low level, only the small diameter BOG switching valve is opened to achieve a small and precise release of BOG gas, avoiding the waste of hydrogen energy caused by the coarse opening of a single large diameter valve in the traditional method; as the pressure inside the cylinder increases, the larger diameter BOG switching valve is gradually opened to quickly reduce the pressure inside the cylinder and improve the safety of system operation. Attached Figure Description

[0038] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0039] Figure 1 This application provides a schematic diagram of the architecture of an onboard liquid hydrogen system for use in a liquid hydrogen fuel cell vehicle. Detailed Implementation

[0040] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0041] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0042] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0043] This application can be applied to the field of hydrogen energy equipment for rail transit. The following will introduce several application scenarios that have been implemented in products, taking liquid hydrogen fuel cell locomotives, hydrogen energy rail engineering vehicles, and hydrogen energy intercity EMUs as examples.

[0044] Liquid hydrogen fuel cell locomotives, hydrogen-powered rail vehicles, or hydrogen-powered intercity EMUs include multiple onboard liquid hydrogen systems used in liquid hydrogen fuel cell locomotives.

[0045] The following section introduces the onboard liquid hydrogen system used in liquid hydrogen fuel cell vehicles.

[0046] See Figure 1 , Figure 1 A schematic diagram of the architecture of an onboard liquid hydrogen system for use in a liquid hydrogen fuel cell vehicle is shown.

[0047] The onboard liquid hydrogen system used in liquid hydrogen fuel cell vehicles includes, but is not limited to: liquid hydrogen cylinder 101, main shut-off valve 102, overcurrent protection valve 103, check valve 104, hydrogen refueling port (with check valve) 105, level gauge 106, pressure sensor 107, first temperature sensor 108, liquid phase outlet valve 109, safety valve 110, vaporizer 111, pressure reducing valve 112, hydrogen supply valve 113, BOG processing valve 114, liquid hydrogen system controller 115, and second temperature sensor 116.

[0048] Understandable Figure 1 The positions of the various valves or sensors are for illustrative purposes only and do not limit the scope of this application.

[0049] Understandably, the hydrogen supply valve 113 is connected to the fuel cell system 200 and can supply hydrogen to the fuel cell system 200.

[0050] The structure of the liquid hydrogen cylinder is explained below.

[0051] The liquid hydrogen cylinder includes a gas phase region and a liquid phase region. The gas phase region is the space occupied by gaseous hydrogen, and the liquid phase region is the space occupied by liquid hydrogen. The gas phase region is provided with a gas phase outlet, and the liquid phase region is provided with a liquid phase outlet.

[0052] The relative sizes of the liquid and gas phase regions change with the liquid hydrogen level. Initially, the liquid phase occupies the majority of the liquid hydrogen cylinder's volume, while the gas phase is only a small reserve space to hold BOG gas and prevent a sudden pressure surge. As liquid hydrogen is continuously discharged through the liquid outlet, the volume of the liquid phase gradually decreases, while the gas phase increases accordingly. If the liquid phase volume shrinks significantly, and the gas phase occupies the majority of the cylinder's volume, the level gauge will trigger a low-level alarm, indicating the need to replenish liquid hydrogen.

[0053] The following section describes the onboard liquid hydrogen system used in liquid hydrogen fuel cell vehicles under three different scenarios.

[0054] Scenario 1: Filling liquid hydrogen cylinder 101 with liquid hydrogen.

[0055] In this scenario, the system involves a level gauge 106, a hydrogen filling port 105, a check valve 104, an overcurrent protection valve 103, a main shut-off valve 102, and a liquid hydrogen system controller 115. In this scenario, check valve 104, overcurrent protection valve 103, and main shut-off valve 102 are all open, while the other valves are closed.

[0056] A level gauge 106 is installed inside the liquid hydrogen cylinder 101 to detect the liquid hydrogen level in the cylinder. A hydrogen filling port 105 communicates with the liquid hydrogen cylinder and is used to receive liquid hydrogen being filled into the cylinder. A one-way valve 104 is installed on the cap of the liquid hydrogen cylinder 101, allowing liquid hydrogen to flow unidirectionally from the hydrogen filling port into the cylinder.

[0057] The liquid hydrogen system controller 115 is connected to the level gauge, hydrogen filling port, check valve, overcurrent protection valve, and main shut-off valve. If a hydrogen filling command is detected, the check valve 104, overcurrent protection valve 103, and main shut-off valve 102 are opened to allow liquid hydrogen to flow unidirectionally from the hydrogen filling port into the liquid hydrogen cylinder. If the liquid level detected by the level gauge reaches a preset liquid level threshold, the check valve 104, overcurrent protection valve 103, and main shut-off valve 102 are closed.

[0058] For example, the method for generating a hydrogen refueling command is as follows: when the liquid hydrogen system controller 115 detects that the liquid hydrogen level in the liquid hydrogen cylinder is lower than the preset filling threshold and the hydrogen refueling port has been sealed and connected with the external hydrogen refueling equipment, the liquid hydrogen system controller 115 automatically generates the command; or, the operator can manually trigger the command through the liquid hydrogen system controller 115.

[0059] This application utilizes a one-way valve 104 to ensure unidirectional flow of liquid hydrogen, preventing backflow during filling. Simultaneously, it works in conjunction with the overflow protection valve 103 and the main shut-off valve 102 to prevent overpressure risks in the pipeline caused by overfilling. A level gauge 106 monitors the liquid level in real time, automatically closing relevant valves when the level reaches a preset threshold, achieving precise quantitative filling and preventing abnormal pressure increases inside the cylinder due to overfilling.

[0060] Scenario 2: Supply hydrogen to fuel cell system 200.

[0061] In scenario two, the following components are involved: overcurrent protection valve 103, main shut-off valve 102, pressure sensor 107, liquid phase outlet valve 109, vaporizer 111, pressure reducing valve 112, hydrogen supply valve 113, liquid hydrogen system controller 115, and first temperature sensor 108. In scenario two, overcurrent protection valve 103, main shut-off valve 102, liquid phase outlet valve 109, pressure reducing valve 112, and hydrogen supply valve 113 are in the open state; pressure sensor 107 and vaporizer 111 are in the working state; and the other valves are in the closed state.

[0062] A liquid phase outlet valve 109 is located at the liquid phase outlet of the liquid hydrogen cylinder, connecting the liquid phase region of the liquid hydrogen cylinder to an external pipeline. A main shut-off valve 102 is connected to the input of the liquid phase outlet valve of the liquid hydrogen cylinder, used to supply liquid hydrogen to the external pipeline; the input of the vaporizer 111 is connected to the output of the liquid phase outlet valve, used to provide heat energy to the liquid hydrogen, converting it into gaseous hydrogen. A first temperature sensor 108 is located at the output of the vaporizer 111, used to detect the temperature of the gaseous hydrogen output by the vaporizer; the input of a pressure reducing valve 112 is connected to the output of the vaporizer, used to regulate the output pressure of the gaseous hydrogen; the input of a hydrogen supply valve 113 is connected to the output of the pressure reducing valve 112. The output of the hydrogen supply valve 113 is connected to the fuel cell 200. An overcurrent protection valve 103 is connected in series between the main shut-off valve 102 and the liquid phase outlet valve 109, used to detect the flow rate of liquid hydrogen output from the external pipeline.

[0063] The liquid hydrogen system controller is connected to the liquid phase outlet valve 109, vaporizer 111, first temperature sensor 108, pressure reducing valve 112, main shut-off valve 102, hydrogen supply valve 113, and overcurrent protection valve 103, respectively.

[0064] The liquid hydrogen system controller is used to open the main shut-off valve 102, overcurrent protection valve 103, liquid phase outlet valve 109, pressure reducing valve 112, and hydrogen supply valve 113 if a hydrogen supply command is detected; close the liquid phase outlet valve 109 and pressure reducing valve 112 if the temperature detected by the first temperature sensor 108 is not within the preset temperature range; and adjust the opening of the pressure reducing valve 112 to regulate the output pressure of gaseous hydrogen if the temperature detected by the first temperature sensor 108 is within the preset temperature range.

[0065] Exemplarily, the method for generating a hydrogen supply instruction is as follows: When the rail transit locomotive starts and the fuel cell system enters the working state (requiring hydrogen supply to maintain power generation), and there are no safety abnormalities in the on-vehicle liquid hydrogen system applied to the liquid hydrogen fuel cell locomotive (such as normal pressure in the liquid hydrogen cylinder, normal operation of the vaporizer, temperature and pressure parameters within the preset range, and no faults in each relevant valve), it is automatically generated by the liquid hydrogen system controller according to the power generation demand of the fuel cell system; or, it is manually triggered by the operator.

[0066] Exemplarily, the preset temperature range can be determined based on the actual situation and will not be limited here.

[0067] Exemplarily, the liquid hydrogen system controller is further configured to: If a hydrogen supply stop instruction is detected, close the hydrogen supply valve 113, the liquid phase outlet valve 109, the pressure reducing valve 112, the main shut-off valve 102, and the overcurrent protection valve 103.

[0068] In this application, the liquid hydrogen is efficiently vaporized into gaseous hydrogen by the vaporizer 111, and the output pressure is precisely regulated in cooperation with the pressure reducing valve 112 to ensure stable and qualified hydrogen supply to the fuel cell system 200. The first temperature sensor 108 continuously monitors the temperature of the hydrogen after vaporization, and automatically cuts off the hydrogen supply path when the temperature exceeds the preset temperature range, preventing the fuel cell system from being damaged by low-temperature or high-temperature hydrogen. The overcurrent protection valve 103 can automatically cut off when the hydrogen supply flow is abnormal. Combined with the linkage control of each valve by the liquid hydrogen system controller, it can quickly respond to faults such as leakage and pipeline rupture, ensuring system safety.

[0069] The liquid hydrogen system controller can adjust the opening degree of the hydrogen supply valve 113 according to the power generation demand of the fuel cell system, achieving precise matching of hydrogen supply and electrical load, and improving the hydrogen energy utilization efficiency.

[0070] Exemplarily, the method for generating a hydrogen supply stop instruction is as follows: When the rail transit locomotive stops and the fuel cell system stops working and no longer requires hydrogen supply, the liquid hydrogen system controller automatically generates a hydrogen supply stop instruction; or, when a safety abnormality occurs during the hydrogen supply process (such as the temperature of the hydrogen after vaporization exceeding the preset temperature range), the liquid hydrogen system controller immediately generates an instruction to cut off the hydrogen supply path; or, the operator manually triggers a hydrogen supply stop operation, or, when the liquid level in the liquid hydrogen cylinder reaches the low liquid level warning threshold, a hydrogen supply stop instruction is generated.

[0071] Situation 3: When no liquid hydrogen is filled into the liquid hydrogen cylinder and no hydrogen is supplied to the fuel cell system, the pressure in the liquid hydrogen cylinder is very high and the BOG gas needs to be released.

[0072] In Situation 3, the BOG treatment valve 114 is involved. Among them, in Situation 3, at least some of the BOG opening valves in the BOG treatment valve 114 are in the open state; other valves are in the closed state.

[0073] The BOG handling valve 114 is located at the gas phase outlet of the liquid hydrogen cylinder; the BOG handling valve 114 includes at least two BOG switching valves; the different BOG switching valves have different diameters, and each BOG switching valve is connected one-to-one with the gas phase area of ​​the liquid hydrogen cylinder 101. The pressure sensor 107 is located in the gas phase area of ​​the liquid hydrogen cylinder and is used to detect the gas pressure in the liquid hydrogen cylinder.

[0074] The liquid hydrogen system controller is used to open the corresponding BOG switching valves in stages, from small diameter to large diameter, based on pressure changes in the gas pressure.

[0075] By opening the BOG treatment valve 114 in stages, the pressure inside the liquid hydrogen cylinder can be precisely controlled, avoiding the waste of hydrogen and sudden pressure drop caused by the crude discharge of a single large-diameter BOG switch valve.

[0076] This application allows gas to be released only through the BOG treatment valve at the gas phase outlet, provided that the main shut-off valve and overcurrent protection valve are closed. This does not affect the airtightness of the main hydrogen supply path and ensures the overall safety of the system.

[0077] Compared to the traditional method of releasing BOG gas using a single large-diameter BOG switch valve, this application uses a staged opening of a small-diameter BOG switch valve to precisely control the release flow rate, minimizing BOG gas emissions while meeting pressure reduction requirements and improving hydrogen storage utilization.

[0078] This application provides an onboard liquid hydrogen system for a liquid hydrogen fuel cell vehicle. The gas phase region of the liquid hydrogen cylinder is used to contain BOG gas generated by liquid hydrogen evaporation, and the gas phase outlet provides a channel for the discharge of BOG gas. A pressure sensor installed in the gas phase region can detect the gas pressure inside the cylinder in real time and transmit the signal to the liquid hydrogen system controller. The BOG handling valve includes at least two BOG switching valves of different diameters and is connected one-to-one with the gas phase region. Based on this working principle, the liquid hydrogen system controller can open the corresponding BOG switching valves in stages according to the pressure changes fed back by the pressure sensor, in the order from small diameter to large diameter: when the pressure inside the cylinder is at a low level, only the small diameter BOG switching valve is opened to achieve a small and precise release of BOG gas, avoiding the waste of hydrogen energy caused by the coarse opening of a single large diameter valve in the traditional method; as the pressure inside the cylinder increases, the larger diameter BOG switching valve is gradually opened to quickly reduce the pressure inside the cylinder and improve the safety of system operation.

[0079] For example, the BOG handling valve 114 includes two or more BOG switching valves. The following description uses an example of a BOG handling valve including eight BOG switching valves. Assume the eight BOG switching valves are arranged in order from smallest to largest diameter as follows: first BOG switching valve, second BOG switching valve, third BOG switching valve, fourth BOG switching valve, fifth BOG switching valve, sixth BOG switching valve, seventh BOG switching valve, and eighth BOG switching valve. Various methods for "opening the corresponding BOG switching valves in stages according to the pressure change of the gas pressure, in order from smallest to largest diameter" are described below. This application provides, but is not limited to, the following three methods.

[0080] The first method includes the following steps A11 to A14.

[0081] Step A11: If the gas pressure is greater than or equal to the first preset pressure threshold and less than the second preset pressure threshold, alternately open the first BOG switch valve and the second BOG switch valve.

[0082] Step A12: If the gas pressure is greater than or equal to the second preset pressure threshold and less than the third preset pressure threshold, control the first BOG switch valve and the second BOG switch valve to be in the open state, and alternately open the third BOG switch valve and the fourth BOG switch valve.

[0083] Step A13: If the gas pressure is greater than or equal to the third preset pressure threshold and less than the fourth preset pressure threshold, control the first BOG switch valve, the second BOG switch valve, the third BOG switch valve and the fourth BOG switch valve to be in the open state, and alternately open the fifth BOG switch valve and the sixth BOG switch valve.

[0084] Step A14: If the gas pressure is greater than or equal to the fourth preset pressure threshold, control the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve and the sixth BOG switch valve to be in the open state, and open the seventh BOG switch valve and the eighth BOG switch valve.

[0085] This application achieves initial pressure reduction by alternately opening small-diameter BOG switch valves to avoid sudden changes in hydrogen flow. Subsequently, the number of BOG switch valves opened is gradually increased to make the gas pressure drop curve in the liquid hydrogen cylinder smoother and reduce disturbances to the gas-liquid balance in the liquid hydrogen cylinder.

[0086] The second method includes the following steps B11 to B18.

[0087] Step B11: If the gas pressure is greater than or equal to the first preset pressure threshold and less than the second preset pressure threshold, open the first BOG switch valve.

[0088] Step B12: If the gas pressure is greater than or equal to the second preset pressure threshold and less than the third preset pressure threshold, keep the first BOG switch valve in the open state and open the second BOG switch valve.

[0089] Step B13: If the gas pressure is greater than or equal to the third preset pressure threshold and less than the fourth preset pressure threshold, keep the first BOG switch valve and the second BOG switch valve in the open state, and open the third BOG switch valve.

[0090] Step B14: If the gas pressure is greater than or equal to the fourth preset pressure threshold and less than the fifth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve and the third BOG switch valve in the open state, and open the fourth BOG switch valve.

[0091] Step B15: If the gas pressure is greater than or equal to the fifth preset pressure threshold and less than the sixth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve and the fourth BOG switch valve in the open state, and open the fifth BOG switch valve.

[0092] Step B16: If the gas pressure is greater than or equal to the sixth preset pressure threshold and less than the seventh preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve and the fifth BOG switch valve in the open state, and open the sixth BOG switch valve.

[0093] Step B17: If the gas pressure is greater than or equal to the seventh preset pressure threshold and less than the eighth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve and the sixth BOG switch valve in the open state, and open the seventh BOG switch valve.

[0094] Step B18: If the gas pressure is greater than or equal to the eighth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve, the sixth BOG switch valve, and the seventh BOG switch valve in the open state, and open the eighth BOG switch valve.

[0095] This application opens the BOG switch valve in sequence from small diameter to large diameter, making the gas pressure drop curve in the liquid hydrogen cylinder smoother and reducing disturbance to the gas-liquid balance in the liquid hydrogen cylinder.

[0096] The third method includes the following steps C11 to C16.

[0097] Step C11: If the gas pressure is greater than or equal to the first preset pressure threshold and less than the second preset pressure threshold, alternately open the first BOG switch valve and the second BOG switch valve.

[0098] Step C12: If the gas pressure is greater than or equal to the second preset pressure threshold and less than the third preset pressure threshold, control the first BOG switch valve and the second BOG switch valve to be in the open state at the same time.

[0099] Step C13: If the gas pressure is greater than or equal to the third preset pressure threshold and less than the fourth preset pressure threshold, keep the first BOG switch valve and the second BOG switch valve in the open state, and alternately open the third BOG switch valve and the fourth BOG switch valve.

[0100] Step C14: If the gas pressure is greater than or equal to the fourth preset pressure threshold and less than the fifth preset pressure threshold, keep the first BOG switch valve and the second BOG switch valve in the open state, and control the third BOG switch valve and the fourth BOG switch valve to be in the open state at the same time.

[0101] Step C15: If the gas pressure is greater than or equal to the fifth preset pressure threshold and less than the sixth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve and the fourth BOG switch valve in the open state, and alternately open the fifth BOG switch valve and the sixth BOG switch valve.

[0102] Step C16: If the gas pressure is greater than or equal to the sixth preset pressure threshold and less than the seventh preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve and the fourth BOG switch valve in the open state, and control the fifth BOG switch valve and the sixth BOG switch valve to be in the open state at the same time.

[0103] Step C17: If the gas pressure is greater than or equal to the seventh preset pressure threshold and less than the eighth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve and the sixth BOG switch valve in the open state, and alternately open the seventh BOG switch valve and the eighth BOG switch valve.

[0104] Step C18: If the gas pressure is greater than or equal to the eighth preset pressure threshold, keep the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve and the sixth BOG switch valve in the open state, and control the seventh BOG switch valve and the eighth BOG switch valve to be in the open state at the same time.

[0105] In one alternative implementation, a second temperature sensor 116 is disposed through the cap of the liquid hydrogen cylinder to detect the temperature inside the liquid hydrogen cylinder. If the liquid hydrogen system controller detects that the temperature inside the liquid hydrogen cylinder is greater than or equal to a preset temperature threshold inside the cylinder, it can control the safety valve to open.

[0106] It should also be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the device embodiment drawings provided in this application, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines.

[0107] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware, or it can be implemented by special-purpose hardware including application-specific integrated circuits, special-purpose CPUs, special-purpose memory, special-purpose components, etc. Generally, any function performed by a computer program can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be diverse, such as analog circuits, digital circuits, or special-purpose circuits. However, for this application, software program implementation is more often the preferred implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium, such as a computer floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk, or optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, training equipment, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0108] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product.

Claims

1. An onboard liquid hydrogen system for use in a liquid hydrogen fuel cell vehicle, characterized in that, include: A liquid hydrogen cylinder for storing liquid hydrogen includes a gas phase region and a liquid phase region. The gas phase region is the space occupied by gaseous hydrogen, and the liquid phase region is the space occupied by liquid hydrogen. The gas phase region is provided with a gas phase outlet, and the liquid phase region is provided with a liquid phase outlet. A vaporized gas (BOG) processing valve is installed at the gas phase outlet of the liquid hydrogen cylinder. The BOG processing valve includes at least two BOG switching valves. The different BOG switching valves have different diameters and are connected one-to-one with the gas phase region of the liquid hydrogen cylinder. A pressure sensor installed in the gas phase region of the liquid hydrogen cylinder is used to detect the gas pressure in the liquid hydrogen cylinder. The liquid hydrogen system controller is used to open the corresponding BOG switching valves in stages, from small diameter to large diameter, based on the pressure changes of the gas pressure.

2. The onboard liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 1, characterized in that, The BOG processing valves, arranged in ascending order of diameter, include the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve, the sixth BOG switch valve, the seventh BOG switch valve, and the eighth BOG switch valve.

3. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 2, characterized in that, When the liquid hydrogen system controller opens the corresponding BOG switching valves in stages according to the pressure changes based on the gas pressure, from small diameter to large diameter, the specific steps include: If the gas pressure is greater than or equal to the first preset pressure threshold and less than the second preset pressure threshold, the first BOG switch valve and the second BOG switch valve are opened alternately. If the gas pressure is greater than or equal to the second preset pressure threshold and less than the third preset pressure threshold, the first BOG switch valve and the second BOG switch valve are controlled to be in the open state, and the third BOG switch valve and the fourth BOG switch valve are alternately opened. If the gas pressure is greater than or equal to the third preset pressure threshold and less than the fourth preset pressure threshold, the first BOG switch valve, the second BOG switch valve, the third BOG switch valve and the fourth BOG switch valve are controlled to be in the open state, and the fifth BOG switch valve and the sixth BOG switch valve are alternately opened. If the gas pressure is greater than or equal to the fourth preset pressure threshold, the first BOG switch valve, the second BOG switch valve, the third BOG switch valve, the fourth BOG switch valve, the fifth BOG switch valve, and the sixth BOG switch valve are controlled to be in the open state, and the seventh BOG switch valve and the eighth BOG switch valve are opened.

4. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 1, characterized in that, Also includes: The liquid phase outlet valve, located at the liquid phase outlet of the liquid hydrogen cylinder, is used to connect the liquid phase area of ​​the liquid hydrogen cylinder with the external pipeline. A main shut-off valve connected to the input end of the liquid phase outlet valve of the liquid hydrogen cylinder is used to supply liquid hydrogen to the external pipeline; A vaporizer, whose input end is connected to the output end of the liquid phase outlet valve, is used to provide heat energy to liquid hydrogen so that liquid hydrogen is converted into gaseous hydrogen. A first temperature sensor is installed at the output end of the vaporizer to detect the temperature of the gaseous hydrogen output by the vaporizer; A pressure reducing valve, whose input is connected to the output of the vaporizer, is used to regulate the output pressure of gaseous hydrogen. A hydrogen supply valve is connected to the output of the pressure reducing valve at its input end, and the output of the hydrogen supply valve is connected to the fuel cell system.

5. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 4, characterized in that, Also includes: An overcurrent protection valve connected in series between the main shut-off valve and the liquid phase outlet valve is used to detect the flow rate of liquid hydrogen flowing through the overcurrent protection valve.

6. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 5, characterized in that, The liquid hydrogen system controller is connected to the overcurrent protection valve and is used to close the overcurrent protection valve if the liquid hydrogen flow rate is greater than or equal to a preset safety threshold.

7. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 4, characterized in that, The liquid hydrogen system controller is connected to the liquid phase outlet valve, the vaporizer, the first temperature sensor, the pressure reducing valve, the main shut-off valve, and the hydrogen supply valve, respectively. The liquid hydrogen system controller is also used to open the main shut-off valve, the liquid phase outlet valve, the pressure reducing valve, and the hydrogen supply valve if a hydrogen supply command is detected; and to close the liquid phase outlet valve, the pressure reducing valve, and the hydrogen supply valve if the temperature detected by the first temperature sensor is not within a preset temperature range. If the temperature detected by the first temperature sensor is within the preset temperature range, the opening of the pressure reducing valve is adjusted to regulate the output pressure of gaseous hydrogen.

8. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 7, characterized in that, The liquid hydrogen system controller is also used for: If a hydrogen supply stop command is detected, the hydrogen supply valve, the liquid phase outlet valve, the pressure reducing valve, and the main shut-off valve are closed.

9. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 1, characterized in that, Also includes: A level gauge installed inside the liquid hydrogen cylinder is used to detect the liquid hydrogen level in the liquid hydrogen cylinder; A hydrogen filling port, which communicates with the liquid phase region of the liquid hydrogen cylinder, is used to receive liquid hydrogen being filled into the liquid hydrogen cylinder; A one-way valve installed on the cap of the liquid hydrogen cylinder allows liquid hydrogen to flow unidirectionally from the hydrogen filling port into the liquid hydrogen cylinder.

10. The on-board liquid hydrogen system for a liquid hydrogen fuel cell vehicle according to claim 9, characterized in that, The liquid hydrogen system controller is connected to the level gauge, the hydrogen filling port, and the one-way valve, respectively. The liquid hydrogen system controller is further configured to: open the one-way valve if a hydrogen addition command is detected, so that liquid hydrogen flows unidirectionally from the hydrogen addition port into the liquid hydrogen cylinder; and close the one-way valve if the liquid level detected by the level gauge reaches a preset liquid level threshold.

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