Power battery fire suppression and cooling system, method and vehicle

Abstract

The present invention belongs to the field of power battery design, and specifically discloses a power battery fire suppression and cooling system, method and vehicle, comprising a lithium battery sealed box system, a liquid nitrogen system and a controller; the sealed box system comprises a box, on which an oxygen concentration sensor, an electrolyte concentration sensor, a temperature concentration sensor, a pressure concentration sensor and a smoke / flame detector are arranged; the liquid nitrogen system comprises a liquid nitrogen tank, which is respectively connected to the sealed box through an air supply pipeline, a liquid supply pipeline and a connecting pipeline, and a first control valve is arranged on the air supply pipeline, a second control valve is arranged on the liquid supply pipeline, and a third control valve is arranged on the connecting pipeline, the air supply pipeline provides nitrogen to the inside of the box, and the liquid supply pipeline provides liquid nitrogen to the box; the pressure in the box is a slightly positive pressure, and the first control valve is in a normally open state.

Description

Technical Field

[0001] The present invention relates to the field of battery cooling, and in particular to a power battery fire suppression and cooling system, method and vehicle. Background Art

[0002] Power batteries are widely used in portable communications, electric vehicles, electric ships, aerospace, large-scale power storage and military fields. For example, existing lithium batteries are widely used due to their high energy density, long cycle life and low environmental pollution. However, the continuous occurrence of safety accidents in recent years has attracted people's attention, such as mobile phone explosions caused by lithium-ion batteries, electric car fires, electric bus combustion, aircraft battery fires, and battery company fires. These serious safety accidents have restricted the application of lithium batteries.

[0003] The main cause of lithium battery fire is heat accumulation, which causes the temperature inside the battery cell to rise, and the electrolyte and other materials decompose and burn. The high temperature generated by the combustion further spreads to adjacent battery cells, causing the combustion to continue to expand and spread. Lithium battery fires are characterized by heat accumulation, rapid temperature rise, and flames that are difficult to extinguish. Therefore, suppressing the combustion of the battery and quickly reducing the internal temperature of the battery in the early stages of thermal runaway are crucial protective measures for battery safety.

[0004] In patent CN 202122445075.9, a power battery box fire suppression device is disclosed, which includes a compressed air tank, a gas separation device, a buffer tank and a controller. The compressed air tank is connected to the gas separation device through an air inlet pipe. The gas separation device is provided with a tail gas exhaust port and an inert gas exhaust port. The gas separation device uses the gas in the compressed air tank as a gas source for gas separation, and the separated oxygen is supplied to the tail gas exhaust port. The remaining inert gas after separating the oxygen is supplied to the inert gas exhaust port. The inert gas exhaust port is connected to the buffer tank through a connecting pipe, and the buffer tank is connected to the exhaust main pipe, and the exhaust main pipe is connected to a number of gas distribution pipes, each gas distribution pipe is connected to a battery box, and a fire detector is provided in the battery box. The battery box is also provided with an exhaust valve, and a gas distribution pipe is provided with a distribution valve. The utility model passes the separated inert gas into the battery box to isolate the contact between the battery cell and oxygen, thereby effectively delaying the spread of the fire inside the battery box, but the patent can only achieve fire suppression, and cannot achieve cooling of the battery inside the battery box.

[0005] Similarly, patent CN 202111044083.0 discloses a power battery box internal detection system and method. The system only warns of fires in the battery box, but cannot suppress the fire or cool down the inside of the battery box.

[0006] In addition, although there are some technologies in the prior art that use liquid nitrogen to cool the box, the control of nitrogen and liquid nitrogen is only simple and rough, and has not been applied in the field of power batteries. When liquid nitrogen cooling is applied in this field, it needs to be controlled according to the actual environment of the power battery. The control is relatively complicated and there is currently no record of related technology. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a power battery fire suppression and cooling system, method and vehicle. The present invention adopts a sealed design for the battery box and replaces the atmospheric environment with high-purity nitrogen, thereby eliminating the combustion aid (oxygen) and preventing the battery from burning in the event of overheating; at the same time, liquid nitrogen is used to quickly cool the battery inside the box.

[0008] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0009] In a first aspect, an embodiment of the present invention provides a power battery fire suppression and cooling system, including a sealed box system, a liquid nitrogen system, and a controller;

[0010] The sealed box system includes a box, on which an oxygen concentration sensor, an electrolyte concentration sensor, a temperature concentration sensor, a pressure concentration sensor and a smoke / flame detector are arranged; the liquid nitrogen system includes a liquid nitrogen tank, which is connected to the sealed box through an air supply pipeline, a liquid supply pipeline and a connecting pipeline, respectively, and a first control valve is arranged on the air supply pipeline, a second control valve is arranged on the liquid supply pipeline, and a third control valve is arranged on the connecting pipeline, the air supply pipeline provides nitrogen to the inside of the box, and the liquid supply pipeline provides liquid nitrogen to the box; and the pressure in the box is a slightly positive pressure, and the first control valve is in a normally open state.

[0011] The controller determines whether to release the pressure of the box according to the pressure value detected by the pressure sensor; the controller determines whether to fill the liquid nitrogen into the liquid nitrogen tank according to the temperature value detected by the temperature detection sensor; the controller determines whether to cut off the battery output according to the monitoring value of the electrolyte concentration sensor; the controller determines whether to replace the oxygen in the box with nitrogen according to the monitoring value of the oxygen concentration sensor; the controller determines whether to fill the liquid nitrogen into the liquid nitrogen tank according to the monitoring value of the smoke / flame detector.

[0012] As a further technical solution, a pair of safety relief valves are also installed on the side of the box.

[0013] As a further technical solution, an electromagnetic relief valve is also installed on the side of the box.

[0014] As a further technical solution, the top of the liquid nitrogen tank is connected to the box body through a gas supply pipeline.

[0015] As a further technical solution, the bottom of the liquid nitrogen tank is connected to the box body through a liquid supply pipeline.

[0016] As a further technical solution, the air supply pipeline is also connected to a purge system.

[0017] As a further technical solution, a pressure reducing valve is also provided on the gas supply pipeline.

[0018] As a further technical solution, the pressure inside the box is a micro-positive pressure, that is, the sealed box is filled with high-purity nitrogen. The micro-positive pressure can ensure that the gas environment inside the box is isolated from the external atmospheric environment. When the box leaks locally, no gas exchange will occur with the air outside the box.

[0019] In a second aspect, the present invention further provides a method for cooling a power battery using a power battery fire suppression and cooling system, as follows:

[0020] The pressure sensor monitors the pressure inside the box. When the pressure sensor issues a first-level overpressure alarm, the controller automatically closes the first control valve and cuts off the nitrogen supply. When the pressure sensor issues a second-level overpressure alarm, the electromagnetic pressure relief valve on the box is automatically opened to release the pressure. When the pressure exceeds the set value, the safety relief valve automatically opens to release the pressure.

[0021] The temperature sensor monitors the temperature inside the box. When the temperature sensor issues a first-level over-temperature alarm, the controller automatically cuts off the battery output; when the temperature sensor issues a second-level over-temperature alarm, the second control valve and the third control valve are automatically opened to fill liquid nitrogen into the box for evaporation and heat absorption and cooling. Considering that the pressure in the liquid nitrogen tank is too low and the liquid nitrogen cannot be discharged quickly, the third control valve can use the pressure difference between the box and the tank to quickly discharge the liquid nitrogen into the box;

[0022] The electrolyte concentration sensor monitors the electrolyte inside the box. When the electrolyte concentration sensor issues an electrolyte leakage alarm, the controller automatically cuts off the battery output for inspection.

[0023] The oxygen concentration sensor monitors the oxygen inside the box. When the oxygen concentration sensor issues an alarm that the oxygen concentration exceeds the standard, nitrogen is filled into the box for gas replacement. If the oxygen concentration continues to exceed the standard, the sealing of the box is checked;

[0024] The smoke / flame detector monitors in real time whether there is smoke / flame in the box. If a smoke / fire level 1 alarm is detected, the controller automatically cuts off the battery output for inspection. If a smoke / fire level 2 alarm is detected, the second control valve and the third control valve are automatically opened to fill liquid nitrogen into the box for evaporation, heat absorption and cooling. Considering that the pressure in the liquid nitrogen tank is too low and the liquid nitrogen cannot be discharged quickly, the third control valve can use the pressure difference between the box and the tank to quickly discharge the liquid nitrogen into the box.

[0025] In a third aspect, the present invention further provides a vehicle on which the power battery fire suppression and cooling system is installed.

[0026] The beneficial effects of the above embodiments of the present invention are as follows:

[0027] 1. The present invention uses a system to comprehensively monitor and control the interior of the battery box, which not only suppresses battery fires, but also reduces the temperature of battery overheating. The entire system is simple in design and relatively practical. Specifically, the present invention uses a liquid nitrogen tank to simultaneously control nitrogen and liquid nitrogen, and the present invention also provides a connecting pipeline to achieve rapid discharge of liquid nitrogen, thereby achieving rapid cooling of overheated batteries in the battery box; further, the first control valve of the present invention is in a normally open state, and the pressure inside the box is a slight positive pressure, that is, the sealed box is filled with high-purity nitrogen. The slight positive pressure can ensure that the gas environment inside the box is isolated from the external atmospheric environment, and when the box leaks locally, no gas exchange occurs with the air outside the box.

[0028] 2. The present invention can also output nitrogen to supply the nitrogen to the purge pipelines of the fuel cell system and the hydrogen storage system to achieve the purge of the fuel cell system.

[0029] 3. Gas replacement can also be performed in the present invention. When the oxygen concentration in the box exceeds the set value, the gas environment in the box can be replaced through the gas supply system. The specific method is: close the bottle mouth solenoid valve, open the box solenoid relief valve, discharge the inert gas in the box, and after the pressure in the box is close to atmospheric pressure, open the bottle mouth solenoid valve to supplement nitrogen for the box. By repeating the deflation / replenishment operation multiple times, the gas replacement in the box is achieved.

[0030] 4. The liquid nitrogen tank is connected to the box through a pressure reducing valve. When the box is connected to the atmosphere due to partial sealing failure or the opening of the safety valve, the container can continuously replenish nitrogen in the box to maintain an inert gas environment in the box;

[0031] 5. The box is equipped with an oxygen concentration sensor and a safety valve to monitor the oxygen content in the box in real time. When the oxygen content exceeds the standard, the gas in the box can be replaced by operating the valve. When the pressure in the box exceeds the limit, the gas in the box is automatically discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 It is a schematic diagram of the structure of the present invention;

[0034] In the figure: 1 liquid filling port, 2 bottle tail valve, 3 liquid nitrogen tank, 4 bottle mouth combination valve, 5 pressure reducing valve, 6 purge system, 7 high and low voltage electrical connectors, 8 oxygen concentration sensor, 9 electrolyte concentration sensor, 10 temperature sensor, 11 pressure sensor, 12 nitrogen, 13 safety pressure relief valve, 14 electromagnetic pressure relief valve, 15 sealed box, 16 battery, 17 smoke and flame detector, 18 gas supply pipeline, 19 liquid supply pipeline, 20 connecting pipeline. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0037] As introduced in the background technology, there are deficiencies in the prior art. In order to solve the above technical problems, the present invention proposes a power battery fire suppression and cooling system and method.

[0038] In a typical embodiment of the present invention, Figure 1 As shown, the power battery fire suppression and cooling system disclosed in this embodiment includes a sealed box system and a liquid nitrogen system; in this embodiment, the battery box adopts a sealed design and replaces the atmospheric environment with high-purity nitrogen, thereby eliminating the combustion aid (oxygen) and preventing the battery from burning in the case of overheating; a slight positive pressure is maintained in the box to prevent the external atmosphere from entering the box due to local sealing failure, resulting in gas exchange.

[0039] The sealed box system in this embodiment includes a sealed box 15, valves and various sensors. Specifically, two redundant safety pressure relief valves 13 and one electromagnetic pressure relief valve 14 are arranged on the box. The sensors include a pressure sensor 11, a temperature sensor 10, an electrolyte concentration sensor 9, an oxygen concentration sensor 8 and a smoke and flame detector 17; the pressure sensor 11, the temperature sensor 10, the electrolyte concentration sensor 9, the oxygen concentration sensor 8 and the smoke and flame detector 17 are inserted into the sealed box 15, the temperature sensor 10 is arranged in the form of a patch on the lithium battery module to monitor the battery module temperature in real time, the electrolyte concentration sensor 9 is installed at the bottom of the box to monitor electrolyte leakage in time, and the temperature sensor 10 and the smoke and flame detector 17 are installed on the upper part of the lithium battery module.

[0040] The functions of each component are as follows:

[0041] The sealed box 15 is a box for installing the battery, which is sealed and filled with high-purity nitrogen (carbon dioxide and inert gas are also applicable) and maintained at a slightly positive pressure (200-400 Pa higher than the atmospheric pressure);

[0042] When the gas pressure in the box exceeds the set value due to heat outside the box, overheating of the battery or failure of the pressure reducing valve, the safety pressure relief valve 13 will be activated to discharge the gas in the box to maintain the pressure value in the box and ensure the safety of the box; if the safety pressure relief valve 13 fails or other operations are required (such as gas replacement, etc.), the electromagnetic pressure relief valve 14 can be used to release the pressure;

[0043] The pressure sensor 11 monitors the gas pressure in the box in real time. If the pressure exceeds the relief pressure of the safety valve, an overpressure alarm is issued. Multiple alarm values ​​can be set.

[0044] The temperature sensor 10 monitors the gas temperature in the box in real time. If the temperature exceeds the set temperature, an over-temperature alarm is issued. Multiple alarm values ​​can be set.

[0045] The electrolyte concentration sensor 9 monitors the electrolyte concentration in the box in real time. If electrolyte is detected, an electrolyte leakage alarm is issued, and multiple alarm values ​​can be set;

[0046] The oxygen concentration sensor 8 monitors the oxygen concentration in the box in real time. If the oxygen concentration exceeds a certain value, a seal failure alarm is issued. Multiple alarm values ​​can be set.

[0047] The smoke and flame detector 17 monitors the presence of smoke / flame in the box in real time. If smoke / flame is detected, a fire alarm is issued, and multiple levels of alarm values ​​can be set.

[0048] The liquid nitrogen system in this embodiment includes a liquid nitrogen tank 3, a bottle mouth combination valve 4, a bottle tail combination valve 2, an air supply pipeline (including a pressure reducing valve 5), a liquid supply pipeline, and a connecting pipeline (including a solenoid valve), and its functions are:

[0049] The liquid nitrogen tank 3 is used to store liquid nitrogen and can withstand a pressure of more than 3MPa; (liquid carbon dioxide and liquid rare gas are also applicable);

[0050] The bottle mouth combination valve 4 is used to output nitrogen to the outside, and has functions such as electromagnetic opening and closing, manual opening and closing, and overpressure relief;

[0051] The combined valve 2 at the end of the bottle is used to output liquid nitrogen to the outside, and has functions such as electromagnetic opening and closing, manual opening and closing, overpressure relief, and liquid nitrogen filling;

[0052] The gas supply pipeline 18 (including the pressure reducing valve) outputs nitrogen to the outside, which is divided into two routes, one route supplies nitrogen to the sealed box, and the other route can supply gas to the purge pipeline of the fuel cell system. Both routes are provided with pressure reducing valves to reduce the pressure of nitrogen;

[0053] The liquid supply pipeline 19 outputs liquid nitrogen to the outside.

[0054] The connecting pipe 20 (solenoid valve) connects the sealed box and the liquid nitrogen tank. When the nitrogen pressure in the tank is too low but liquid nitrogen needs to be supplied to the outside, the solenoid valve can be opened to use the pressure in the box to press the liquid nitrogen out;

[0055] The above-mentioned box maintains a non-flammable environment, and the sealed box is filled with high-purity nitrogen (carbon dioxide and inert gas are also applicable). The slight positive pressure can ensure that the gas environment in the box is isolated from the external atmospheric environment. When the box leaks locally, there will be no gas exchange with the air outside the box.

[0056] When the box is connected to the atmosphere due to partial sealing failure or safety valve failure, the liquid nitrogen system can continuously replenish nitrogen in the box to maintain the nitrogen environment and slight positive pressure in the box. The implementation method is as follows: the solenoid valve of the bottle mouth combination valve of the liquid nitrogen tank is kept open under normal conditions, and the gas pressure is reduced to the set pressure through the pressure reducing valve in the gas supply pipeline (the set pressure maintains pressure balance with the gas in the box).

[0057] The pressure safety of the box in this embodiment is mainly ensured by the safety pressure relief valve 13 and the electromagnetic pressure relief valve 14. The safety pressure relief valve 13 and the electromagnetic pressure relief valve 14 ensure that the pressure in the box does not exceed the set pressure.

[0058] In the battery overheating cooling method of this embodiment, when it is detected that the battery may have thermal runaway, the solenoid valve at the end of the bottle is opened, and liquid nitrogen is sprayed into the sealed box under the action of gravity and the nitrogen pressure on the upper part of the liquid nitrogen tank 3, and efficient cooling is achieved by evaporation and heat absorption.

[0059] The gas replacement method in this embodiment can replace the gas environment in the box through the gas supply system when the oxygen concentration in the box exceeds the set value. The specific method is: close the bottle mouth solenoid valve, open the box solenoid pressure relief valve 14, discharge the inert gas in the box, and after the pressure in the box is close to the atmospheric pressure, open the bottle mouth solenoid valve to supplement nitrogen for the box. By repeating the deflation / replenishment operation multiple times, the gas replacement in the box is achieved.

[0060] The nitrogen output method in this embodiment supplies nitrogen to the purge pipelines of the fuel cell system and the hydrogen storage system by opening the pipeline solenoid valve, thereby achieving the purge of the fuel cell system.

[0061] The control method of the whole system is as follows:

[0062] The pressure sensor 11 monitors the pressure inside the box. When the pressure sensor 11 issues a first-level overpressure alarm, the controller automatically closes the bottle mouth combination valve and cuts off the nitrogen supply. When the pressure sensor issues a second-level overpressure alarm, the controller automatically opens the electromagnetic pressure relief valve 14 to release the pressure. When the pressure exceeds the set value, the safety pressure relief valve automatically opens to release the pressure.

[0063] The temperature sensor 10 monitors the temperature inside the box. When the temperature sensor 10 issues a first-level over-temperature alarm, the controller automatically cuts off the battery output; when the temperature sensor issues a second-level over-temperature alarm, the combined bottle valve at the end of the bottle is opened to fill the box with liquid nitrogen for evaporation and heat absorption and cooling. If the pressure in the liquid nitrogen tank is too low and the liquid nitrogen cannot be discharged quickly, the solenoid valve in the connecting pipeline can use the pressure difference between the box and the tank to quickly discharge the liquid nitrogen into the box;

[0064] The electrolyte concentration sensor 9 monitors the electrolyte inside the box. When the electrolyte concentration sensor issues an electrolyte leakage alarm, the controller automatically cuts off the battery output for inspection;

[0065] The oxygen concentration sensor 8 monitors the oxygen inside the box. When the oxygen concentration sensor 8 issues an alarm indicating that the oxygen concentration exceeds the standard, gas replacement can be performed through remote control. If the oxygen concentration continues to exceed the standard, it will prompt to check the sealing of the box.

[0066] The smoke and flame detector 17 monitors the presence of smoke / flame in the box in real time. If a smoke / fire level 1 alarm is detected, the battery output is cut off by the controller for inspection. If a smoke / fire level 2 alarm is detected, the combined bottle valve at the bottle tail is opened to fill liquid nitrogen into the box for evaporation, heat absorption and cooling. If the pressure in the liquid nitrogen tank is too low and the liquid nitrogen cannot be discharged quickly, the solenoid valve of the connecting pipeline is opened to use the pressure difference between the box and the tank to quickly discharge the liquid nitrogen into the box.

[0067] This embodiment also provides a vehicle, on which the power battery cooling system described above is installed. Since the vehicle is provided with the power battery cooling system described above, the vehicle also has all the advantages described above. In some embodiments, the vehicle provided by the present invention can be any appropriate type of vehicle, including some ships, etc.

[0068] Finally, it should be noted that relational terms such as first and second are merely used to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A power battery fire suppression and cooling system, comprising a sealed box system, a liquid nitrogen system and a controller; characterized in that: The sealed box system comprises a box, on which an oxygen concentration sensor, an electrolyte concentration sensor, a temperature sensor, a pressure sensor and a smoke and flame detector connected to a controller are arranged; the liquid nitrogen system comprises a liquid nitrogen tank, which is connected to the sealed box through an air supply pipeline, a liquid supply pipeline and a connecting pipeline, respectively; a first control valve is arranged on the air supply pipeline, a second control valve is arranged on the liquid supply pipeline, and a third control valve is arranged on the connecting pipeline; the air supply pipeline provides nitrogen to the inside of the box, and the liquid supply pipeline provides liquid nitrogen to the box; the pressure in the box is a slightly positive pressure, and the first control valve is in a normally open state; The top of the liquid nitrogen tank is connected to the box through an air supply pipeline; the bottom of the liquid nitrogen tank is connected to the box through a liquid supply pipeline; the connecting pipeline and the air supply pipeline are connected in parallel to the top of the liquid nitrogen tank.

2. The power battery fire suppression and cooling system according to claim 1, characterized in that: A pair of safety pressure relief valves are also installed on the side of the box body.

3. The power battery fire suppression and cooling system according to claim 1, characterized in that: An electromagnetic pressure relief valve is also installed on the side of the box.

4. The power battery fire suppression and cooling system according to claim 1, characterized in that: The air supply pipeline is also connected to the purge system.

5. The power battery fire suppression and cooling system according to claim 1, characterized in that: A pressure reducing valve is also provided on the gas supply pipeline.

6. A method for cooling a power battery using a fire suppressant using the power battery fire suppression and cooling system according to any one of claims 1 to 5, characterized in that: The pressure sensor monitors the pressure inside the box. When the pressure sensor issues a first-level overpressure alarm, the controller automatically closes the first control valve and cuts off the nitrogen supply. When the pressure sensor issues a second-level overpressure alarm, the controller automatically opens the electromagnetic pressure relief valve on the box to release pressure. When the pressure exceeds the set value, the safety pressure relief valve automatically opens to release pressure. The temperature sensor monitors the temperature inside the box. When the temperature sensor issues a first-level over-temperature alarm, the controller automatically cuts off the battery output; when the temperature sensor issues a second-level over-temperature alarm, the controller automatically opens the second control valve and the third control valve to fill liquid nitrogen into the box for evaporation and heat absorption and cooling. Considering that the pressure in the liquid nitrogen tank is too low and the liquid nitrogen cannot be discharged quickly, the pipeline where the third control valve is located can use the pressure difference between the box and the tank to quickly discharge the liquid nitrogen into the box; The electrolyte concentration sensor monitors the electrolyte inside the box. When the electrolyte concentration sensor issues an electrolyte leakage alarm, the controller automatically cuts off the battery output for inspection. The oxygen concentration sensor monitors the oxygen inside the box. When the oxygen concentration sensor issues an alarm that the oxygen concentration exceeds the standard, gas replacement is performed through remote control. If the oxygen concentration continues to exceed the standard, it prompts to check the sealing of the box; The smoke and flame detector monitors in real time whether there is smoke / flame in the box. If a smoke / fire level 1 alarm is detected, the controller cuts off the battery output for inspection. If a smoke / fire level 2 alarm is detected, the second control valve is opened to fill liquid nitrogen into the box for evaporation, heat absorption and cooling. If the pressure in the liquid nitrogen tank is too low and the liquid nitrogen cannot be discharged quickly, the third control valve is opened to use the pressure difference between the box and the tank to quickly discharge the liquid nitrogen into the box.

7. A vehicle, characterized in that: A power battery fire suppression and cooling system as described in any one of claims 1 to 5 is installed thereon.

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