Vehicle-mounted liquid nitrogen fire extinguishing system

Abstract

The application belongs to the technical field of fire extinguishing, and particularly relates to a vehicle-mounted liquid nitrogen fire extinguishing system, which comprises a carrying vehicle, a liquid nitrogen storage and supply unit, a self-pressurizing and pressure maintaining unit, a spraying execution unit and an intelligent control unit arranged on the carrying vehicle; the carrying vehicle comprises a cab and a carriage for carrying each functional unit and realizing rapid and mobile deployment; the liquid nitrogen storage and supply unit comprises a liquid nitrogen storage tank arranged in the carriage, a safety exhaust valve, a pressure sensor and a temperature sensor arranged on the top of the liquid nitrogen storage tank, and a liquid nitrogen outlet arranged at the bottom of the liquid nitrogen storage tank; the self-pressurizing and pressure maintaining unit comprises a pressure maintaining vaporizer, a pressure stabilizing valve group and a backflow pipeline, and the liquid inlet of the pressure maintaining vaporizer is connected with the liquid nitrogen outlet at the bottom of the liquid nitrogen storage tank through a first electromagnetic valve. The vehicle-mounted liquid nitrogen fire extinguishing system can realize rapid and mobile deployment, has the self-pressurizing and pressure maintaining function, and can realize intelligent and graded fire extinguishing.

Description

Technical Field

[0001] This invention belongs to the field of fire extinguishing technology, specifically relating to a vehicle-mounted liquid nitrogen fire extinguishing system. Background Technology

[0002] Liquid nitrogen, as a highly efficient and clean fire extinguishing medium, has extremely low temperature and high expansion ratio. Its extinguishing mechanism mainly includes: rapidly absorbing a large amount of heat, reducing the temperature of the fire scene, making combustion unsustainable; at the same time, it generates a large amount of inert nitrogen gas, diluting the oxygen concentration and achieving suffocation extinguishing; moreover, nitrogen gas is non-polluting and non-corrosive to the environment and the protected objects, making it particularly suitable for special scenarios such as precision equipment fires, electrical fires, oil fires, and hazardous chemical fires.

[0003] Currently, most liquid nitrogen fire extinguishing systems are either fixed systems or small mobile devices. Fixed systems are typically installed in specific hazardous areas and are difficult to quickly transfer to different fire scenes; while small mobile devices are easy to carry, their limited capacity makes them unsuitable for large-area fires or long-term continuous spraying. Furthermore, liquid nitrogen is prone to pressure fluctuations in storage tanks due to natural evaporation and continuous output during storage and transportation. Existing systems often require external gas sources or manual intervention to maintain pressure, affecting the continuity and stability of the fire extinguishing response. For complex fire scenes, existing liquid nitrogen spraying devices also generally suffer from the problem of difficulty in coordinating the spray direction, flow rate, and operating pressure according to changes in the fire intensity, resulting in low liquid nitrogen utilization, insufficient fire extinguishing accuracy, and requiring operators to work at close range in high-temperature, smoke, or explosion-risk environments, leading to poor safety. Therefore, it is still necessary to provide a vehicle-mounted liquid nitrogen fire extinguishing system that combines rapid deployment, stable tank pressure maintenance, and graded control of the spraying process. Summary of the Invention

[0004] The purpose of this invention is to provide a vehicle-mounted liquid nitrogen fire extinguishing system that can be quickly and mobilely deployed, has a self-pressurization and pressure-maintaining function, and can achieve intelligent graded fire extinguishing.

[0005] The specific technical solution adopted by this invention is as follows: A vehicle-mounted liquid nitrogen fire extinguishing system includes a transport vehicle, and a liquid nitrogen storage and supply unit, a self-pressurizing and pressure-maintaining unit, a spraying execution unit, and an intelligent control unit installed on the transport vehicle; the transport vehicle includes a driver's cab and a cargo compartment, used to carry the various functional units and achieve rapid mobile deployment; the liquid nitrogen storage and supply unit includes a liquid nitrogen tank installed in the cargo compartment, the top of the liquid nitrogen tank is equipped with a safety vent valve, a pressure sensor, and a temperature sensor, the bottom of the liquid nitrogen tank is equipped with a liquid nitrogen outlet, and the middle of the liquid nitrogen tank is equipped with a level gauge; The self-pressurizing and pressure-maintaining unit includes a pressure-maintaining vaporizer, a pressure-stabilizing valve group, and a reflux pipeline. The liquid inlet of the pressure-maintaining vaporizer is connected to the liquid nitrogen outlet at the bottom of the liquid nitrogen storage tank via a first solenoid valve. The gas outlet of the pressure-maintaining vaporizer is connected to the gas phase space at the top of the liquid nitrogen storage tank via the pressure-stabilizing valve group. One end of the reflux pipeline is connected to the gas outlet of the pressure-maintaining vaporizer, and the other end of the reflux pipeline is connected to the reflux interface of the liquid nitrogen storage tank via a second solenoid valve. The injection execution unit includes a cryogenic delivery pipeline, a third solenoid valve, a cryogenic liquid pump, and a flexible... The system includes a flexible connecting hose and a spraying device. One end of the cryogenic delivery pipeline is connected to the liquid nitrogen outlet at the bottom of the liquid nitrogen storage tank. After passing through a third solenoid valve and a cryogenic liquid pump, the cryogenic delivery pipeline is connected to the spraying device via a flexible connecting hose. The cryogenic liquid pump is an ultra-low temperature centrifugal pump connected to the bottom of the liquid nitrogen storage tank. The intelligent control unit includes a main controller, a data acquisition module, and an execution drive module. The signal input terminals of the data acquisition module are connected to the pressure sensor, temperature sensor, and level gauge of the liquid nitrogen storage tank, as well as the fire monitoring sensor installed outside the vehicle or on the spraying device. The control output terminals of the execution drive module are connected to the first solenoid valve, the second solenoid valve, the third solenoid valve, the drive motor of the cryogenic liquid pump, and the flow regulating valve of the spraying device. The main controller automatically controls the actions of each solenoid valve, the cryogenic liquid pump, and the flow regulating valve according to the storage tank status parameters and fire status parameters acquired by the data acquisition module and a preset control strategy, thereby realizing self-pressurization and pressure maintenance of liquid nitrogen and staged fire extinguishing spraying.

[0006] Preferably, the spraying device includes an electric rotating gimbal, a cryogenic spray gun mounted on the gimbal, and a DC nozzle connected to the outlet of the cryogenic spray gun. The rotation angle of the gimbal is automatically adjusted by the main controller according to the fire monitoring signal.

[0007] Preferably, the fire monitoring sensor includes an infrared thermal imager and a flame detector, both of which are mounted on the spraying device, and the main controller integrates an image recognition module for automatically identifying the location of the fire source and the range of the fire.

[0008] Preferably, the intelligent control unit further includes a wireless communication module, which is used to interact with the remote monitoring platform.

[0009] Preferably, the pressure-maintaining vaporizer is a finned tube ambient air vaporizer, the finned tube of which is made of aluminum alloy or copper alloy, and the pressure-stabilizing valve group includes a pressure regulating valve, a safety valve and a check valve connected in sequence.

[0010] Preferably, both the cryogenic delivery pipeline and the flexible connecting hose adopt a composite insulation structure, with the inner tube being a corrugated stainless steel pipe and the outer tube being a braided metal hose.

[0011] Preferably, the carriage has a storage tank cavity and a storage container cavity on both sides, the liquid nitrogen storage tank is located inside the storage tank cavity, and the pressure-holding vaporizer is installed inside the storage container cavity.

[0012] Preferably, the outer side of the storage tank cavity is connected to a door panel via a hinge, the door panel is provided with an observation window, and the outer side of the storage tank cavity is provided with an accordion-style telescopic cover.

[0013] Preferably, the control strategy configured in the main controller includes a pressure-maintaining mode and a fire-extinguishing mode. In the pressure-maintaining mode, when the pressure of the liquid nitrogen storage tank is lower than the preset lower threshold, the self-pressurizing and pressure-maintaining unit is activated to replenish the pressure, and when the pressure of the liquid nitrogen storage tank is higher than the preset upper threshold, the pressure relief protection is activated. In the fire-extinguishing mode, the main controller determines the location of the fire source and the fire intensity based on the signals from the fire monitoring sensors, and automatically adjusts the spray flow rate, the speed of the cryogenic liquid pump, and the spray direction to perform graded fire extinguishing.

[0014] The technical effects achieved by this invention are as follows: This invention integrates a liquid nitrogen storage and supply unit, a self-pressurizing and pressure-maintaining unit, a spraying execution unit, and an intelligent control unit onto a transport vehicle. This allows for rapid deployment to the fire scene and immediate firefighting operations, overcoming the slow response of fixed firefighting systems and the small capacity of mobile firefighting devices. It is particularly suitable for the rapid response to large fires, hazardous chemical accidents, and fires in remote areas. The self-pressurizing and pressure-maintaining unit utilizes the nitrogen generated by the vaporization of liquid nitrogen to pressurize and maintain the pressure of the storage tank. This prevents liquid nitrogen loss caused by passive pressure relief due to continuous pressure increases caused by environmental heat leakage, while ensuring the driving pressure required for firefighting spraying. No external gas source or mechanical booster pump is needed, resulting in a simple structure and reliable operation.

[0015] In this invention, the main controller integrates two control strategies: pressure-holding mode and fire-extinguishing mode. In pressure-holding mode, it automatically replenishes or releases pressure. In fire-extinguishing mode, based on real-time data collected by fire monitoring sensors such as infrared thermal imagers and flame detectors regarding the fire source location, fire range, and heat radiation intensity, it automatically adjusts the speed of the cryogenic liquid pump, the flow regulating valve of the spray device, and the direction of the electric rotating gimbal to achieve graded adaptive control of spray flow, pressure, and direction. Furthermore, the intelligent control unit simultaneously features automatic control mode, manual mode, and a handheld remote control terminal. Under normal circumstances, automatic fire extinguishing can be initiated with a single button. In special environments or complex fire scenes, operators can switch to manual mode from inside the cab and remotely control the gimbal attitude, spray start / stop, and flow rate via a handheld remote control terminal, keeping operators away from dangerous areas such as high temperatures, toxic fumes, and explosions, thus ensuring personal safety. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the installation of the liquid nitrogen storage tank and pressure-holding vaporizer of the present invention; Figure 3 This is a three-dimensional schematic diagram of the piping connection of the fire extinguishing system of the present invention; Figure 4 This is a side-view perspective three-dimensional schematic diagram of the pipeline connection of the fire extinguishing system of the present invention; Figure 5 This is a schematic diagram illustrating the working principle of the fire extinguishing system of this invention.

[0017] The attached diagram lists the components represented by each number as follows: 1. Transport vehicle; 101. Cab; 102. Cargo compartment; 103. Tank cavity; 104. Storage chamber; 2. Liquid nitrogen storage tank; 201. Safety exhaust valve; 202. Pressure sensor; 203. Temperature sensor; 204. Level gauge; 3. Pressure-holding vaporizer; 301. First solenoid valve; 4. Pressure stabilizing valve group; 401. Pressure regulating valve; 402. Safety valve; 403. Check valve; 5. Return pipeline; 501. Second solenoid valve; 6. Cryogenic delivery pipeline; 601. Third solenoid valve; 602. Cryogenic liquid pump; 7. Spraying device; 701. Pan-tilt unit; 702. Cryogenic spray gun; 703. DC nozzle; 8. Fire monitoring sensor; 9. Main controller; 10. Data acquisition module; 11. Execution drive module; 12. Wireless communication module. Detailed Implementation

[0018] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0019] like Figures 1-5 As shown, a vehicle-mounted liquid nitrogen fire extinguishing system includes a transport vehicle 1 for carrying various functional units and enabling rapid deployment, and a liquid nitrogen storage and supply unit, a self-pressurizing and pressure-maintaining unit, a spray execution unit, and an intelligent control unit installed on the transport vehicle 1. The transport vehicle 1 includes a driver's cab 101 and a cargo compartment 102, with a human-machine interface terminal installed in the driver's cab 101. The liquid nitrogen storage and supply unit includes a liquid nitrogen storage tank 2 installed in the cargo compartment 102. The top of the liquid nitrogen storage tank 2 is equipped with a safety vent valve 201, a pressure sensor 202, and a temperature sensor 203. When the pressure inside the tank exceeds the specified value, the system will release the liquid nitrogen. The pressure relief system automatically activates when the set value is reached to ensure safety. Liquid nitrogen storage tank 2 has a liquid nitrogen outlet at its bottom and a level gauge 204 in its middle for continuous monitoring of the remaining liquid nitrogen level. The self-pressurizing and pressure-maintaining unit includes a pressure-maintaining vaporizer 3, a pressure-stabilizing valve group 4, and a return pipeline 5. The inlet of the pressure-maintaining vaporizer 3 is connected to the liquid nitrogen outlet at the bottom of liquid nitrogen storage tank 2 via a first solenoid valve 301, and the outlet of the pressure-maintaining vaporizer 3 is connected to the gas phase space at the top of liquid nitrogen storage tank 2 via a pressure-stabilizing valve group 4. One end of the return pipeline 5 is connected to the outlet of the pressure-maintaining vaporizer 3, and the other end of the return pipeline 5 is connected to the second solenoid valve group 4. Solenoid valve 501 is connected to the return port of liquid nitrogen storage tank 2. The design of this return pipeline 5 allows the residual cryogenic gas in the pipeline to be safely returned to liquid nitrogen storage tank 2 after the pressure holding process is completed, preventing the vaporizer from overcooling and frosting or overpressure. The pressure holding vaporizer 3 is a finned tube ambient temperature vaporizer, and its finned tubes are made of aluminum alloy or copper alloy. The pressure regulating valve group 4 includes a pressure regulating valve 401, a safety valve 402, and a one-way valve 403 connected in sequence, which are used to stabilize the high-pressure nitrogen gas output from the vaporizer to a set value and then send it into the top gas phase space of liquid nitrogen storage tank 2. The self-pressurizing and pressure holding unit uses... To maintain the liquid nitrogen storage tank 2 at the required working pressure during the injection process and avoid the impact on the pump's suction performance caused by a drop in tank pressure due to a large output of liquid nitrogen, when the pressure sensor 202 detects that the tank pressure is lower than the set lower limit during operation, the main controller 9 opens the first solenoid valve 301, and the liquid nitrogen enters the vaporizer to vaporize, and is then replenished into the gas phase space through the pressure stabilizing valve group 4; if the pressure recovers to the upper limit, the first solenoid valve 301 is closed; if the tank pressure is too high, the second solenoid valve 501 is opened, allowing excess nitrogen to return to the liquid in the tank through the return pipeline 5, which serves to reduce pressure and stir the liquid phase temperature. like Figures 3-5As shown, the spraying execution unit includes a cryogenic delivery pipeline 6, a third solenoid valve 601, a cryogenic liquid pump 602, a flexible connecting hose, and a spraying device 7. Both the cryogenic delivery pipeline 6 and the flexible connecting hose adopt a composite insulation structure, with an inner tube made of corrugated stainless steel and an outer tube made of braided metal hose. One end of the cryogenic delivery pipeline 6 is connected to the liquid nitrogen outlet at the bottom of the liquid nitrogen storage tank 2. The third solenoid valve 601 and the cryogenic liquid pump 602 are sequentially arranged along the liquid nitrogen delivery direction and connected to the spraying device 7 via the flexible connecting hose. The cryogenic liquid pump 602 is used to pressurize and deliver liquid nitrogen to meet the needs of spraying distance and pipeline pressure drop compensation. The spraying device 7 is equipped with a fire monitoring sensor to collect fire information in the extinguishing area. In the non-spraying state, the third solenoid valve 601 is closed; after entering the extinguishing state, the main controller 9 controls the third solenoid valve 601 to open and adjusts the working state of the cryogenic liquid pump 602 and the flow regulating valve according to the fire state to control the spraying intensity. like Figure 5 As shown, the intelligent control unit includes a main controller 9, a data acquisition module 10, and an execution drive module 11. The main controller 9 can be a PLC or an embedded industrial computer and is located in a control cabinet within the driver's cab 101. The data acquisition module 10 is used to collect pressure, temperature, and liquid level signals from the liquid nitrogen storage tank 2, as well as fire information collected by the fire monitoring sensor 8. The execution drive module 11 is connected to the drive motors of the first solenoid valve 301, the second solenoid valve 501, the third solenoid valve 601, the cryogenic liquid pump 602, and the flow regulating valve of the spray device 7, respectively, and is used to execute control commands issued by the main controller 9. The fire monitoring sensor 8 includes an infrared thermal imager and a flame detector, both of which can be installed on the spray device 7 to acquire information on the location of the fire source and changes in fire intensity. Based on the collected tank status parameters and fire status parameters, the main controller 9 controls the self-pressurizing and pressure-maintaining unit and the spray execution unit to work collaboratively under different operating conditions.

[0020] like Figure 5 As shown, the intelligent control unit also includes a wireless communication module 12, which is used to interact with the remote monitoring platform. This module is not only used to connect to the handheld remote control terminal, but also to interact with the remote monitoring platform to upload key information such as vehicle location, tank status, fire scene images, and fire extinguishing progress in real time, and to receive remote commands.

[0021] like Figure 1 and Figure 2As shown, the outer hinge of the storage tank cavity 103 is connected to a door panel, and an observation window is provided on the door panel to facilitate direct reading of the liquid level gauge 204 without opening the vehicle door. The outer side of the storage tank cavity 104 is provided with a bellows-style telescopic cover, which can protect the internal equipment from wind, sand and rain erosion when driving, and can be quickly opened when in use to provide sufficient air convection space for the vaporizer and ensure air-temperature vaporization efficiency.

[0022] like Figure 5 As shown, the control strategy configured by the main controller 9 includes a pressure-holding mode and a fire-extinguishing mode. In the pressure-holding mode, when the pressure sensor 202 detects that the pressure of the liquid nitrogen storage tank 2 is lower than the preset lower limit, the main controller 9 controls the first solenoid valve 301 to open, allowing liquid nitrogen to enter the pressure-holding vaporizer 3, vaporize, and then be replenished into the top gas phase space of the liquid nitrogen storage tank 2 via the pressure-stabilizing valve group 4; when the tank pressure is detected to return to the preset range, the first solenoid valve 301 is controlled to close; when the tank pressure is higher than the preset upper limit, the second solenoid valve 501 is controlled to operate to provide pressure relief protection. In fire extinguishing mode, the main controller 9 determines the fire level based on the fire information collected by the fire monitoring sensor 8, and controls the operation of the third solenoid valve 601, the cryogenic liquid pump 602, and the flow regulating valve accordingly. When the fire is small, the tank's own pressure can be used for spraying. When the fire increases, the cryogenic liquid pump 602 is activated to increase the spraying capacity. During the spraying process, the main controller 9 continuously monitors the liquid level and pressure. When the liquid level is detected to be lower than the safe value or the pump is malfunctioning, the cryogenic liquid pump 602 is stopped and the third solenoid valve 601 is closed. After the fire is extinguished, the second solenoid valve 501 is activated to backflow or drain the residual cryogenic medium in the relevant pipelines.

[0023] The working principle of this invention is as follows: In standby mode, the main controller 9 reads the pressure sensor 202 and temperature sensor 203 at the top of the liquid nitrogen storage tank 2 and the liquid level gauge 204 in the middle in real time through the data acquisition module 10 to obtain the gas phase pressure, liquid phase temperature and liquid nitrogen balance inside the liquid nitrogen storage tank 2. When the pressure of the liquid nitrogen storage tank 2 is lower than the preset lower threshold, the main controller 9 automatically opens the first solenoid valve 301, and the liquid nitrogen flows out from the bottom outlet of the storage tank and enters the pressure-holding vaporizer 3. The liquid nitrogen absorbs ambient heat and vaporizes in the vaporizer, expanding in volume. The purified high-pressure nitrogen gas returns to the top gas phase space of the liquid nitrogen storage tank 2 via the pressure stabilizing valve group 4, thereby increasing the pressure inside the tank. If the pressure is too high and exceeds the upper limit threshold, the main controller 9 can open the second solenoid valve 501 to release pressure through the return pipeline 5, maintaining stable system pressure and ready to enter fire extinguishing mode at any time. During fire extinguishing operations, the fire monitoring sensor 8 installed on the spray device 7 collects fire signals in real time. The image recognition module in the main controller 9 automatically analyzes the location of the fire source, the range of the fire, and the level. At the same time, the main controller 9 uses the pan-tilt unit 701... The system uses sensor signals to determine the angle of the fire source relative to the spraying device 7. Based on the fire intensity, it automatically calculates the required spray flow rate, the speed of the cryogenic liquid pump 602, and the spray direction. It then executes the drive module 11 to control the rotation of the electric rotating platform 701, aligning the cryogenic spray gun 702 and the DC nozzle 703 with the fire source area. The main controller 9 opens the third solenoid valve 601 and starts the cryogenic liquid pump 602. Liquid nitrogen is pressurized by the cryogenic liquid pump 602 from the bottom outlet of the storage tank through the cryogenic delivery pipeline 6 to the high pressure required for fire extinguishing. The pressurized liquid nitrogen is then delivered to the cryogenic spray gun 702 of the spraying device 7 through a flexible connecting hose. The main controller 9 adjusts the flow regulating valve on the spraying device 7 according to the fire intensity to achieve graded spraying, i.e., low flow for small fires and high flow for large fires. The liquid nitrogen is sprayed towards the fire source in the form of a DC jet, rapidly vaporizing. Through the dual mechanism of isolating oxygen and absorbing heat to cool down, it achieves rapid fire extinguishing. Finally, through the wireless communication module 12, the main controller 9 can upload the system status, fire scene images, spray parameters, etc. to the remote monitoring platform in real time and receive remote commands.

[0024] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A vehicle-mounted liquid nitrogen fire extinguishing system, comprising a transport vehicle (1), said transport vehicle (1) comprising a driver's cab (101) and a cargo compartment (102); characterized in that: It also includes a liquid nitrogen storage and supply unit, a self-pressurizing and pressure-maintaining unit, an injection execution unit and an intelligent control unit installed on the transport vehicle (1); The liquid nitrogen storage and supply unit includes a liquid nitrogen storage tank (2) installed in the carriage (102); The self-pressurizing and pressure-maintaining unit includes a pressure-maintaining vaporizer (3), a pressure-stabilizing valve group (4), and a return pipeline (5). The liquid inlet of the pressure-maintaining vaporizer (3) is connected to the liquid nitrogen outlet at the bottom of the liquid nitrogen storage tank (2) through a first solenoid valve (301). The gas outlet of the pressure-maintaining vaporizer (3) is connected to the gas phase space at the top of the liquid nitrogen storage tank (2) through a pressure-stabilizing valve group (4). One end of the return pipeline (5) is connected to the gas outlet of the pressure-maintaining vaporizer (3), and the other end is connected to the return interface of the liquid nitrogen storage tank (2) through a second solenoid valve (501). The injection execution unit includes a cryogenic delivery pipeline (6), a third solenoid valve (601), a cryogenic liquid pump (602), a flexible connecting hose, and an injection device (7). One end of the cryogenic delivery pipeline (6) is connected to the liquid nitrogen outlet at the bottom of the liquid nitrogen storage tank (2). The cryogenic delivery pipeline (6) is provided with a third solenoid valve (601) and a cryogenic liquid pump (602) in sequence along the liquid nitrogen flow direction, and is connected to the injection device (7) via a flexible connecting hose. The intelligent control unit is electrically connected to the first solenoid valve (301), the second solenoid valve (501), the third solenoid valve (601), the cryogenic liquid pump (602), and the flow regulating valve of the spraying device (7), respectively. It is used to collect the status parameters of the liquid nitrogen storage tank (2) and the fire status parameters. In the pressure holding mode, it controls the nitrogen generated by the pressure holding vaporizer (3) to be replenished into the gas phase space at the top of the liquid nitrogen storage tank (2) through the pressure stabilizing valve group (4) to maintain the working pressure of the storage tank. In the fire extinguishing mode, it controls the third solenoid valve (601), the cryogenic liquid pump (602), and the flow regulating valve to operate according to the fire intensity level in order to achieve graded fire extinguishing spray.

2. The vehicle-mounted liquid nitrogen fire extinguishing system according to claim 1, characterized in that: The liquid nitrogen storage tank (2) is equipped with a safety vent valve (201), a pressure sensor (202) and a temperature sensor (203) at the top, a liquid nitrogen outlet at the bottom, and a level gauge (204) in the middle.

3. The vehicle-mounted liquid nitrogen fire extinguishing system according to claim 2, characterized in that: The intelligent control unit includes a main controller (9), a data acquisition module (10), and an execution drive module (11). The signal input terminal of the data acquisition module (10) is connected to the pressure sensor (202), temperature sensor (203), and level gauge (204) of the liquid nitrogen storage tank (2), as well as the fire monitoring sensor (8) installed outside the carriage (102) or on the spray device (7). The control output terminal of the execution drive module (11) is connected to the drive motor of the first solenoid valve (301), the second solenoid valve (501), the third solenoid valve (601), the cryogenic liquid pump (602), and the flow regulating valve of the spray device (7).

4. The vehicle-mounted liquid nitrogen fire extinguishing system according to claim 3, characterized in that: The spraying device (7) includes an electric rotating gimbal (701), a low-temperature spray gun (702) mounted on the gimbal (701), and a DC nozzle (703) connected to the outlet of the low-temperature spray gun (702). The rotation angle of the gimbal (701) is automatically adjusted by the main controller (9) according to the fire monitoring signal.

5. A vehicle-mounted liquid nitrogen fire extinguishing system according to claim 3, characterized in that: The fire monitoring sensor (8) includes an infrared thermal imager and a flame detector. Both the infrared thermal imager and the flame detector are installed on the spray device (7), and the main controller (9) integrates an image recognition module for automatically identifying the location of the fire source and the range of the fire.

6. A vehicle-mounted liquid nitrogen fire extinguishing system according to claim 3, characterized in that: The intelligent control unit also includes a wireless communication module (12), which is used to interact with the remote monitoring platform.

7. A vehicle-mounted liquid nitrogen fire extinguishing system according to claim 1, characterized in that: The pressure-holding vaporizer (3) is a finned tube air-temperature vaporizer, and its finned tube is made of aluminum alloy or copper alloy. The pressure-stabilizing valve group (4) includes a pressure regulating valve (401), a safety valve (402) and a one-way valve (403) connected in sequence.

8. A vehicle-mounted liquid nitrogen fire extinguishing system according to claim 1, characterized in that: The cryogenic delivery pipeline (6) and the flexible connecting hose both adopt a composite insulation structure, with the inner tube being a corrugated stainless steel pipe and the outer tube being a braided metal hose.

9. A vehicle-mounted liquid nitrogen fire extinguishing system according to claim 1, characterized in that: The carriage (102) has a storage tank cavity (103) and a storage container cavity (104) on both sides. The liquid nitrogen storage tank (2) is located inside the storage tank cavity (103), and the pressure-holding vaporizer (3) is installed inside the storage container cavity (104). The outer side of the storage tank cavity (103) is connected to a door panel by a hinge, and an observation window is provided on the door panel. The outer side of the storage tank cavity (104) is provided with an accordion-style telescopic cover.

10. A vehicle-mounted liquid nitrogen fire extinguishing system according to claim 3, characterized in that: The main controller (9) is configured to perform graded spray control in fire extinguishing mode. In the first stage of fire extinguishing, the third solenoid valve (601) is opened and the liquid nitrogen storage tank (2) is used for spraying. In the second stage of fire extinguishing, the cryogenic liquid pump (602) is started and the flow regulating valve is controlled to be in a partially open state. In the third stage of fire extinguishing, the speed of the cryogenic liquid pump (602) is increased and the self-pressurizing and pressure-maintaining unit is opened to maintain the working pressure of the liquid nitrogen storage tank (2). During the spraying process, when the liquid level is detected to be lower than the safe value, the cryogenic liquid pump (602) is stopped and the third solenoid valve (601) is closed.

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