Hierarchical Thermal Runaway Protection Battery Pack Device, Method and System

Abstract

The present application provides a hierarchical thermal runaway protection battery pack device, method and system. The device includes a battery pack mechanism, a first heat dissipation mechanism and a second heat dissipation mechanism. The battery pack mechanism includes a box body and a plurality of battery cells. The box body is provided with a convex beam located on the outer periphery of the battery cells. The convex beam is provided with openings at intervals, and refrigerant nozzles are installed in the openings. The first heat dissipation mechanism includes a refrigeration device, a circulation pipeline and a water-cooled plate. A water pump and a fourth valve are provided in the middle of the circulation pipeline; the second heat dissipation mechanism includes a refrigerant storage tank. The present application provides a hierarchical thermal runaway protection battery pack device. By setting the first heat dissipation mechanism and the second heat dissipation mechanism, water cooling can be enabled at a relatively high temperature; when the temperature exceeds the warning threshold or the temperature rise rate exceeds the warning threshold, high-speed water cooling and box body refrigerant refrigeration are started simultaneously; when thermal runaway occurs, a heat dissipation method of direct refrigerant spraying refrigeration is started, effectively improving the thermal runaway protection ability and safety performance of the battery pack.

Description

Technical Field

[0001] This application relates to the technical field of thermal runaway protection for battery packs, and particularly to a battery pack device, method, and system for hierarchical thermal runaway protection. Background Art

[0002] With the development and popularization of new energy vehicles, the ownership of electric vehicles has been continuously increasing. However, the number of safety accidents caused by thermal runaway of power batteries has also gradually increased. In recent years, the causes of many electric vehicle fires, explosions, and other accidents have been directly attributed to the thermal runaway of power batteries. The safety of power batteries is particularly important for electric vehicles. Developing an efficient temperature control system is of great significance for ensuring the thermal safety of power batteries. Summary of the Invention

[0003] Embodiments of this application provide a battery pack device, method, and system for hierarchical thermal runaway protection to solve the technical problem of poor thermal runaway protection effect of the battery pack in related technologies, resulting in low safety performance.

[0004] In a first aspect, this application provides a battery pack device for hierarchical thermal runaway protection, including:

[0005] A battery pack mechanism, including a box body and a plurality of battery cells disposed in the box body. The box body is provided with convex beams on the periphery of the plurality of battery cells. The plurality of convex beams and the frame of the box body are both hollow structures and communicate with each other. The convex beams are provided with openings at intervals, and refrigerant nozzles are installed in each of the plurality of openings.

[0006] A first heat dissipation mechanism, including a refrigeration device, a circulation pipeline, and a water-cooled plate. The refrigeration device is used to cool the coolant in the circulation pipeline. The two ends of the circulation pipeline are connected to the liquid inlet and outlet of the water-cooled plate. A water pump and a fourth valve are provided in the middle of the circulation pipeline. The liquid outlet of the water-cooled plate is also branched and connected to a water outlet pipeline, and a third valve is provided on the water outlet pipeline.

[0007] A second heat dissipation mechanism, including a refrigerant storage tank. The refrigerant storage tank is communicated with the frame of the box body through a second pipeline. A second valve is provided on the second pipeline. The refrigerant storage tank intersects and communicates with the circulation pipeline through a first pipeline, and a first valve is provided on the first pipeline.

[0008] In some embodiments, the fourth valve is located between the water pump and the liquid inlet of the water-cooled plate.

[0009] In some embodiments, the convex beams include a plurality of cross beams and longitudinal beams, and the refrigerant nozzles are evenly spaced horizontally or vertically on the cross beams or longitudinal beams.

[0010] In some embodiments, the refrigerant nozzles are inclined towards the direction of the adjacent battery cells.

[0011] In some embodiments, the refrigeration device includes a refrigeration circuit, and a compressor, a condenser, a fan, an expansion valve, and a battery cooler provided on the refrigeration circuit. The coolant in the circulation pipeline is cooled in the battery cooler.

[0012] In a second aspect, the present application provides a method applied to the hierarchical thermal runaway protection battery pack device as described above, including the following steps:

[0013] Step S1: Obtain the temperature value inside the battery pack;

[0014] Step S21: When the temperature value inside the battery pack is lower than the thermal runaway warning temperature threshold, control the first valve, the second valve, and the third valve to close, and the fourth valve to open;

[0015] Step S22: When the temperature value inside the battery pack is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold, control the fourth valve and the second valve to open simultaneously, the first valve and the third valve to close, and the water pump to operate at the highest speed;

[0016] Step S23: When the temperature value inside the battery pack exceeds the thermal runaway temperature threshold, control the refrigerant nozzle to open, and at the same time, the first valve and the third valve to open, and the fourth valve to close;

[0017] Wherein, the thermal runaway temperature threshold is greater than the thermal runaway warning temperature threshold.

[0018] In some embodiments, step S23 further includes the following steps:

[0019] When the temperature value inside the battery pack exceeds the thermal runaway temperature threshold, control to send a thermal runaway warning signal.

[0020] In a third aspect, the present application provides a system applied to the hierarchical thermal runaway protection battery pack device as described above, including:

[0021] A battery pack temperature value acquisition module, configured to acquire the temperature value inside the battery pack;

[0022] A first thermal runaway protection module, communicatively connected to the battery pack temperature value acquisition module, and configured to control the first valve, the second valve, and the third valve to close, and the fourth valve to open when the temperature value inside the battery pack is lower than the thermal runaway warning temperature threshold;

[0023] A second thermal runaway protection module, communicatively connected to the battery pack temperature value acquisition module, and configured to control the fourth valve and the second valve to open simultaneously, the first valve and the third valve to close, and the water pump to operate at the highest speed when the temperature value inside the battery pack is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold;

[0024] The third thermal runaway protection module is communicatively connected to the battery pack temperature value acquisition module, and is configured to control the refrigerant nozzle to open, and at the same time, the first valve and the third valve to open and the fourth valve to close when the temperature value in the battery pack exceeds the thermal runaway temperature threshold;

[0025] Wherein, the thermal runaway temperature threshold is greater than the thermal runaway warning temperature threshold.

[0026] In some embodiments, the third thermal runaway protection module further includes:

[0027] An alarm sub-module, communicatively connected to the battery pack temperature value acquisition module, and is configured to control the sending of a thermal runaway alarm signal when the temperature value in the battery pack exceeds the thermal runaway temperature threshold.

[0028] In some embodiments, it further includes:

[0029] A battery cell positioning unit, configured to obtain the position of each battery cell in the battery pack;

[0030] A nozzle control unit, the nozzle control unit is communicatively connected to the battery pack temperature value acquisition module and the battery cell positioning unit, and when the temperature value of the battery cell exceeds the thermal runaway temperature threshold, it controls the nozzle adjacent to the module to open.

[0031] The beneficial effects brought by the technical solution provided in this application include:

[0032] The embodiment of this application provides a hierarchical thermal runaway protection battery pack device. Due to the setting of the first heat dissipation mechanism and the second heat dissipation mechanism, it is possible to implement a three-level protection measure of starting coolant cooling at a lower temperature, starting high-speed water cooling at a higher temperature, and starting refrigerant heat dissipation during thermal runaway, effectively improving the thermal runaway protection ability and safety performance of the battery pack. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 It is a connection schematic diagram of the hierarchical thermal runaway protection battery pack device provided in the embodiment of this application;

[0035] Figure 2 It is a battery pack structure schematic diagram of the hierarchical thermal runaway protection battery pack device provided in the embodiment of this application;

[0036] Figure 3The method flow chart of the hierarchical thermal runaway protection method provided by the embodiment of the present application;

[0037] Figure 4 The functional module block diagram of the hierarchical thermal runaway protection system provided by the embodiment of the present application.

[0038] In the figure: 1. Battery pack; 111. Convex beam; 112. Refrigerant nozzle; 113. Refrigerant inlet; 15. Battery cell; 12. Water-cooled plate; 121. Liquid inlet; 122. Liquid outlet; 13. Circulation pipeline; 131. Water pump; 132. Fourth valve; 14. Refrigerant storage tank; 141. First pipeline; 142. First valve; 143. Second pipeline; 144. Second valve; 16. Water outlet pipeline; 161. Third valve; 171. Condenser; 172. Fan; 173. Expansion valve; 174. Battery cooler; 175. Compressor; 100. Battery pack temperature value acquisition module; 210. First thermal runaway protection module; 220. Second thermal runaway protection module; 230. Third thermal runaway protection module. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0040] With the development and popularization of new energy vehicles, the ownership of electric vehicles has been continuously increasing, and the safety problems of electric vehicles have gradually increased. Among them, the main reason for the safety problems is the thermal runaway problem of power batteries.

[0041] In view of this, please refer to Figure 1-2 , the present application provides a hierarchical thermal runaway protection battery pack device, including:

[0042] A battery pack mechanism, including a box body and a plurality of battery cells 15 arranged in the box body. The box body is provided with convex beams 111 on the periphery of the plurality of battery cells. The convex beams 111 and the frame of the box body are both hollow structures and communicate with each other. The convex beams 111 are provided with openings at intervals, and refrigerant nozzles 112 are installed in the plurality of openings. The refrigerant nozzles are used to open to spray refrigerant to adjacent battery cells when the temperature in the battery pack exceeds the thermal runaway temperature threshold.

[0043] The first heat dissipation mechanism includes a refrigeration device, a circulation pipeline 13, and a water-cooled plate 12. The refrigeration device is used to cool the coolant in the circulation pipeline 13. Both ends of the circulation pipeline 13 are respectively connected to the liquid inlet 121 and the liquid outlet 122 of the water-cooled plate 12. A water pump 131 and a fourth valve 132 are arranged in the middle of the circulation pipeline 13. The liquid outlet 122 of the water-cooled plate 12 is also branched and connected to a water outlet pipeline 16, and a third valve 161 is arranged on the water outlet pipeline 16;

[0044] The second heat dissipation mechanism includes a refrigerant storage tank 14. The refrigerant storage tank 14 is connected to the hollow frame of the box body through a second pipeline 143. A second valve 144 is arranged on the second pipeline 143. The refrigerant storage tank 14 communicates with the circulation pipeline 13 through a first pipeline 141, and a first valve 142 is arranged on the first pipeline 141.

[0045] When the temperature value in the battery pack 1 is relatively high or lower than the thermal runaway warning temperature threshold, control the first valve, the second valve, and the third valve to close, and the fourth valve to open. Only the coolant in the circulation pipeline 13 is used to cool and dissipate heat from multiple battery cells 15 in the box body. When the temperature in the battery pack 1 is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold, control the fourth valve and the second valve to open simultaneously, the first valve and the third valve to close, and the water pump 131 to operate at the highest speed, so as to realize that the coolant in the circulation pipeline 13 flows to the water-cooled plate 12 at the highest speed, and combine with the refrigerant transported into the box body to dissipate heat from the battery pack 1. When the temperature value in the battery pack 1 reaches the thermal runaway temperature threshold, control the refrigerant nozzle to open and the first valve and the third valve to open, and the fourth valve to close. The refrigerant is sprayed from the refrigerant storage tank, through the frame of the box body, the convex beam, and the refrigerant nozzle with an opening in the convex beam to the adjacent battery cells, discharging the oxygen in the battery pack 1 while refrigerating, playing a role in extinguishing the fire.

[0046] The embodiment of the present application provides a battery pack device with hierarchical thermal runaway protection. Due to the setting of the first heat dissipation mechanism and the second heat dissipation mechanism, it can be realized that when the temperature is relatively high, the coolant cooling is started; when the temperature exceeds the thermal runaway warning temperature threshold, the high-speed water cooling and the refrigerant cooling are started simultaneously; when the temperature in the battery pack exceeds the thermal runaway temperature threshold, the refrigerant is directly sprayed on the battery cells for refrigeration, effectively improving the thermal runaway protection ability and safety performance of the battery pack 1.

[0047] As described above, the thermal runaway temperature threshold is the thermal runaway temperature value of the battery pack 1, which can be set according to battery packs 1 with different chemical properties.

[0048] As described above, the water-cooled plate 12 is located at the bottom of the multiple battery cells, and it can be realized as a single water-cooled plate 12 or multiple water-cooled plates 12.

[0049] In one embodiment, the fourth valve 132 is located between the water pump 131 and the liquid inlet 121 of the water-cooled plate 12. The water pump 131 drives the coolant cooled by the refrigeration device in the circulation pipeline 13 to flow directionally towards the water-cooled plate 12, playing a role in cooling and heat dissipation.

[0050] As described above, the coolant can be implemented as water.

[0051] In one embodiment, the convex beam includes a cross beam and a longitudinal beam, which are located on the outer periphery of a plurality of battery cells. When the outer periphery of the battery cell is the frame of the box body, this convex beam is not provided, and the refrigerant nozzles 112 are arranged at uniform intervals horizontally or vertically in the openings of the cross beam or the longitudinal beam.

[0052] In one embodiment, the refrigerant nozzles 112 are arranged to be inclined towards the adjacent battery cells. In order to achieve the rapid injection of the refrigerant into the battery pack chamber obliquely above the battery cells 15 on the inner periphery of the plurality of refrigerant nozzles 112 and onto the surfaces of the battery cells 15, achieving the effect of rapid cooling and fire extinguishing.

[0053] In one embodiment, the first valve 142 is located between the fourth valve 132 and the liquid inlet 121 of the water-cooled plate 12. When the temperature value inside the battery pack 1 is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold, the fourth valve and the second valve are controlled to open, the first valve and the third valve are closed, the water pump operates at the highest speed, and the coolant in the circulation pipeline 13 flows through the water-cooled plate 12 at the highest speed, achieving the highest water-cooling effect. The second valve is opened, and the refrigerant enters the cavity of the box body of the battery pack through the second pipeline, discharging the oxygen in the cavity, playing a role in rapid refrigeration. When the temperature value inside the battery pack exceeds the thermal runaway temperature threshold, the first valve and the third valve are controlled to open, the fourth valve is closed, the refrigerant enters the water circuit of the water-cooled plate through the first pipeline, enters the frame and the convex beam of the box body of the battery pack through the second pipeline, discharges the oxygen in the cavity, and sprays the battery cells in the cavity of the box body of the battery pack through the refrigerant nozzles, playing a role in rapidly cooling the battery cells 15 in the cavity.

[0054] In one embodiment, the refrigeration device includes a refrigeration circuit and a condenser 171, a compressor 175, a battery cooler 174, and an expansion valve 173 provided on the refrigeration circuit. A part of the circulation pipeline 13 is arranged inside the battery cooler 174, and a fan 172 is arranged near the condenser 171.

[0055] Based on the same inventive concept, please refer to Figure 3 , the present application provides a method applied to the hierarchical thermal runaway protection battery pack 1 device as described above, which is characterized by including the following steps:

[0056] Step S1, obtaining the temperature value inside the battery pack 1;

[0057] Step S21: When the temperature value inside the battery pack 1 is lower than the thermal runaway warning temperature threshold or the difference between the temperature value and the thermal runaway temperature threshold reaches the warning temperature difference, the first valve, the second valve, and the third valve are controlled to be closed, and the fourth valve is opened, so that the battery pack 1 is kept within a safe temperature range by cooling with coolant alone;

[0058] Step S22: When the temperature value inside the battery pack 1 is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold, the battery pack 1 is determined to be in a critical state for triggering thermal runaway. The fourth valve and the second valve are controlled to be open simultaneously, and the first valve and the third valve are closed. The water pump 131 is operated at the highest speed for a specified time to achieve the best coolant cooling effect. The second pipeline in the refrigerant storage tank 14 enters the frame and convex beam of the box body. The refrigerant expands and vaporizes to absorb heat, quickly removing heat from the battery, reducing the temperature, and preventing the occurrence of thermal runaway.

[0059] Step S23: When the temperature inside the battery pack 1 exceeds the thermal runaway temperature threshold, the refrigerant nozzle is controlled to open, and at the same time, the first valve and the third valve are opened, and the fourth valve is closed. The high-pressure refrigerant is discharged from the water channel of the water-cooled plate through the water channel and the water outlet pipe, cooling the battery in the form of a refrigerant. Another path enters the frame and convex beam of the box through the second pipe and sprays the refrigerant nozzle on the surface of the battery cell, vaporizing and absorbing heat, rapidly cooling the battery cell to prevent the occurrence of thermal diffusion events. At the same time, the refrigerant can expel oxygen from the battery pack 1 to extinguish the fire.

[0060] Wherein, the thermal runaway temperature threshold is greater than the thermal runaway warning temperature threshold.

[0061] In one embodiment, the step S23 further includes the following steps:

[0062] When the temperature value in the battery pack 1 exceeds the thermal runaway temperature threshold, the control sends a thermal runaway warning signal.

[0063] In one embodiment, the following steps are further included:

[0064] Obtaining the position information of each battery cell in the battery pack;

[0065] The step S1 is specifically implemented as obtaining the temperature value of each battery cell;

[0066] When the temperature value of a battery cell exceeds the thermal runaway temperature threshold, the refrigerant nozzle adjacent to the battery cell is controlled to open, so as to spray the refrigerant obliquely upward toward the adjacent battery cell.

[0067] In a modified embodiment of the present application, it is also possible to implement targeted spraying of refrigerant with a battery module consisting of a plurality of battery cells as a group.

[0068] Based on the same inventive concept, please refer to Figure 4 , this application provides a system applied to the hierarchical thermal runaway protection battery pack device as described above, including:

[0069] A battery pack temperature value acquisition module 100, configured to acquire the temperature value inside the battery pack;

[0070] A first thermal runaway protection module 210, communicatively connected to the battery pack temperature value acquisition module, configured to control the first valve, the second valve, and the third valve to close and the fourth valve to open when the temperature value inside the battery pack is lower than the thermal runaway warning temperature threshold;

[0071] A second thermal runaway protection module 220, communicatively connected to the battery pack temperature value acquisition module, configured to control the fourth valve and the second valve to open simultaneously, the first valve and the third valve to close, and the water pump to operate at the highest speed when the temperature value inside the battery pack is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold;

[0072] A third thermal runaway protection module 230, communicatively connected to the battery pack temperature value acquisition module, configured to control the refrigerant nozzle to open, the first valve and the third valve to open, and the fourth valve to close when the temperature value inside the battery pack exceeds the thermal runaway temperature threshold;

[0073] Wherein, the thermal runaway temperature threshold is greater than the thermal runaway warning temperature threshold.

[0074] In one embodiment, the third thermal runaway protection module further includes:

[0075] An alarm sub-module, communicatively connected to the battery pack temperature value acquisition module, configured to control the sending of a thermal runaway alarm signal when the temperature value inside the battery pack exceeds the thermal runaway temperature threshold.

[0076] In one embodiment, the system provided by this application further includes:

[0077] A battery cell positioning unit, configured to acquire the position of each battery cell inside the battery pack;

[0078] A nozzle control unit, the nozzle control unit is communicatively connected to the battery pack temperature value acquisition module and the battery cell positioning unit, the battery pack temperature value acquisition module is configured to acquire the temperature value of each battery cell, and the nozzle control unit is configured to control the refrigerant nozzle adjacent to the battery cell to open when the temperature value of the battery cell exceeds the thermal runaway temperature threshold.

[0079] As described above, the vicinity of the battery cell is the convex beam closest to the periphery of the battery cell.

[0080] In one embodiment, a thermal runaway alarm signal is sent through the BMS, and the position of the thermal runaway battery is sent.

[0081] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installed", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0082] It should be noted that in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0083] The above description is only the specific implementation manners of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A hierarchical thermal runaway protection battery pack device, characterized in that Comprising: A battery pack mechanism, including a box body and a plurality of battery cells disposed within the box body. The box body is provided with convex beams located on the outer periphery of the plurality of battery cells. The plurality of convex beams and the frame of the box body are both of hollow structure and communicate with each other. The convex beams are spaced apart with openings provided thereon, and refrigerant nozzles are installed in each of the plurality of openings; A first heat dissipation mechanism, including a refrigeration device, a circulation pipeline, and a water-cooled plate. The refrigeration device is used to cool the coolant in the circulation pipeline. The two ends of the circulation pipeline are connected to the liquid inlet and outlet of the water-cooled plate. A water pump and a fourth valve are provided in the middle of the circulation pipeline. The fourth valve is located between the water pump and the liquid inlet of the water-cooled plate. The liquid outlet of the water-cooled plate is also branched and connected to a water outlet pipeline, and a third valve is provided on the water outlet pipeline; A second heat dissipation mechanism, including a refrigerant storage tank. The refrigerant storage tank is communicated with the frame of the box body through a second pipeline. A second valve is provided on the second pipeline. The refrigerant storage tank intersects and communicates with the circulation pipeline through a first pipeline. A first valve is provided on the first pipeline; A method applied to the hierarchical thermal runaway protection battery pack device described above, including the following steps: Step S1, obtaining the temperature value inside the battery pack; Step S21, when the temperature value inside the battery pack is lower than the thermal runaway warning temperature threshold, controlling the first valve, the second valve, and the third valve to close and the fourth valve to open; Step S22, when the temperature value inside the battery pack is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold, controlling the fourth valve and the second valve to open simultaneously, the first valve and the third valve to close, and the water pump to operate at the highest speed; Step S23, when the temperature value inside the battery pack exceeds the thermal runaway temperature threshold, controlling the refrigerant nozzle to open and simultaneously the first valve and the third valve to open, and the fourth valve to close; Wherein, the thermal runaway temperature threshold is greater than the thermal runaway warning temperature threshold.

2. The hierarchical thermal runaway protection battery pack device according to claim 1, wherein The convex beams include a plurality of cross beams and longitudinal beams, and the refrigerant nozzles are uniformly spaced horizontally or vertically on the cross beams or longitudinal beams.

3. The hierarchical thermal runaway protection battery pack device according to claim 2, wherein, The refrigerant nozzle is inclined towards the direction of the adjacent battery cell.

4. The hierarchical thermal runaway protection battery pack device according to claim 1, characterized in that, The refrigeration device includes a refrigeration circuit and a compressor, a condenser, a fan, an expansion valve, and a battery cooler provided on the refrigeration circuit. The coolant in the circulation pipeline is cooled in the battery cooler.

5. The hierarchical thermal runaway protection battery pack device according to claim 1, characterized in that, The step S23 further includes the following steps: When the temperature value inside the battery pack exceeds the thermal runaway temperature threshold, controlling to send a thermal runaway warning signal.

6. A system applied to the hierarchical thermal runaway protection battery pack device as described in any one of claims 1-4, characterized in that, Comprising: A battery pack temperature value acquisition module, used to acquire the temperature value inside the battery pack; A first thermal runaway protection module, communicatively connected to the battery pack temperature value acquisition module, used to control the first valve, the second valve, and the third valve to close and the fourth valve to open when the temperature value inside the battery pack is lower than the thermal runaway warning temperature threshold; A second thermal runaway protection module, communicatively connected to the battery pack temperature value acquisition module, used to control the fourth valve and the second valve to open simultaneously, the first valve and the third valve to close, and the water pump to operate at the highest speed when the temperature value inside the battery pack is between the thermal runaway warning temperature threshold and the thermal runaway temperature threshold; The third thermal runaway protection module, which is communicatively connected to the battery pack temperature value acquisition module, is configured to control the opening of the refrigerant nozzle, the opening of the first valve and the third valve, and the closing of the fourth valve when the temperature value inside the battery pack exceeds the thermal runaway temperature threshold; Wherein, the thermal runaway temperature threshold is greater than the thermal runaway warning temperature threshold.

7. The system according to claim 6, wherein The third thermal runaway protection module further includes: An alarm sub-module, which is communicatively connected to the battery pack temperature value acquisition module, is configured to control the sending of a thermal runaway alarm signal when the temperature value inside the battery pack exceeds the thermal runaway temperature threshold.

8. The system according to claim 6, characterized in that, It further includes: A battery cell positioning unit, which is configured to obtain the position of each battery cell inside the battery pack; A nozzle control unit, which is communicatively connected to the battery pack temperature value acquisition module and the battery cell positioning unit, and is configured to control the opening of the nozzle adjacent to the battery cell when the temperature value of the battery cell exceeds the thermal runaway temperature threshold.

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