Battery pack with dynamically adjusted pre-tension distribution

Abstract

The application relates to the technical field of batteries, in particular to a battery pack capable of dynamically adjusting pre-tightening force distribution, which comprises a bottom shell and internal cell modules, a separation structure is arranged in the bottom shell to divide the space of the bottom shell into a control cavity and a cell cavity, and the cell cavity is divided into an upper cell mounting area and a lower emergency area; a module box is arranged in the cell mounting area, a hydraulic capsule is mounted in a side wall clamping groove of the module box, the hydraulic capsule is filled with incompressible hydraulic oil and is connected with a hydraulic control mechanism through a pipeline; cells are arranged between the hydraulic capsules, and the hydraulic capsules exert adjustable pre-tightening force on the side walls of the cells; the hydraulic control mechanism comprises an oil box, a piezoelectric pump and a piezoelectric regulating valve, and the piezoelectric pump adjusts the pressure of the hydraulic capsule based on sensor data; a sensing network is arranged in the battery pack and comprises a piezoresistive film sensor on the inner wall of the hydraulic capsule, a distributed temperature sensor on a sealing cover and a piezoelectric film array sensor on the inner wall of the bottom shell; and the battery pack can achieve the purpose of improving safety.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a battery pack with dynamically adjustable preload distribution. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage systems, lithium-ion batteries have become the mainstream power source due to their high energy density and long cycle life. As the core component of a battery system, the battery pack's structural design directly affects the battery's safety, reliability, and lifespan. During battery operation, the cells expand in volume during charging and discharging, especially under high-rate or extreme temperature conditions. Without effective mechanical restraint, cell expansion can lead to electrode material cracking, increased contact resistance, and even internal short circuits, seriously threatening the battery pack's safety performance.

[0003] Currently, traditional battery packs typically apply static preload to the cells using rigid frames, fixed force springs, or bolt preload. However, these methods have the following drawbacks: The preload is not adjustable: The static preload cannot adapt to the expansion differences of the battery cell under different states of charge, temperatures and aging stages. This causes the battery cell to be subjected to excessive pressure when the expansion is low, which accelerates material aging, while the constraint is insufficient when the expansion is high, which leads to poor contact or local stress concentration.

[0004] Lack of dynamic response capability: Existing technologies are unable to monitor the cell status and adjust the preload in real time, especially in sudden situations such as thermal runaway or mechanical impact, and cannot quickly provide targeted protection, increasing the risk of thermal propagation and structural failure.

[0005] Limitations of uniform force application: Traditional solutions typically apply a uniform preload to all cells in the battery pack, ignoring the uneven expansion caused by manufacturing tolerances or differences in operating conditions between cells, which further exacerbates performance degradation and safety hazards. Summary of the Invention

[0006] The purpose of this invention is to provide a battery pack with dynamically adjustable preload distribution to improve battery pack safety and solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a battery pack with dynamically adjustable preload distribution, comprising a bottom shell and internal cell modules, wherein a partition structure is provided inside the bottom shell to divide the bottom shell space into a control cavity and a cell cavity, and the cell cavity is further divided into an upper cell mounting area and a lower emergency area; A module box is set up in the cell installation area, and a hydraulic bladder is installed in the slot on its side wall. The hydraulic bladder is filled with incompressible hydraulic oil and connected to a hydraulic control mechanism through pipelines. Cells are arranged between the hydraulic bladders, and the hydraulic bladders apply an adjustable preload to the side wall of the cell. The hydraulic control mechanism includes an oil box, a piezoelectric pump, and a piezoelectric regulating valve. The piezoelectric pump adjusts the pressure of the hydraulic bladder based on sensor data. The battery pack is equipped with a sensing network, including a piezoresistive thin-film sensor on the inner wall of the hydraulic bladder, a distributed temperature sensor on the sealing cover, and a piezoelectric thin-film array sensor on the inner wall of the bottom shell. The emergency zone is equipped with a liftable protection plate, which is connected to the hydraulic bladder via a piston transmission mechanism, a diaphragm-connecting pipe, and a manifold. When an impact signal is triggered, the piezoelectric pump pressurizes the diaphragm inside the connecting pipe, and the hydraulic oil drives the piston transmission mechanism to lift the protection plate to the side of the battery cell.

[0008] The partition structure includes a vertically arranged first partition, a horizontally arranged second partition, and a third partition located in the middle of the cell cavity; The upper part of the cell cavity has horizontal ribs in the cell mounting area, which divide the upper cavity into independent slots for inserting cell modules.

[0009] The bottom of the module box is provided with a through groove that corresponds one-to-one with the upper limit groove of the second partition, and the top of the module box is provided with a sealing cover, which is fixed on the module box. The limiting groove on the second partition is used to allow the protection plate to pass through and enter the module box.

[0010] The hydraulic bladder is fitted into the outer frame, and the outer frame is fixed in the slot on the side wall of the module box. Two to four battery cells are arranged between two adjacent hydraulic bladders. All hydraulic bladders in the same battery cell module are connected to the same shunt pipe, which is installed on the top of the module box.

[0011] The end of the shunt pipe is connected to a connector pipe via a flange. The connector pipe is a flexible hose and is connected to the piezoelectric regulating valve via a threaded connector. The oil box of the hydraulic control mechanism is located in the installation space formed by the third partition.

[0012] The piezoelectric regulating valve has a dual-channel structure, which is connected to the piezoelectric pump and the oil box respectively, and is used to control the mechanical pressure of the hydraulic bladder.

[0013] Among them, the piezoresistive thin-film sensor is used to detect the real-time contact pressure between the hydraulic bladder and the battery cell, the distributed temperature sensor is used to detect the local temperature of a single battery cell module, and the piezoelectric thin-film array sensor is used to sense the impact on the battery pack and locate the impact location and intensity through signal analysis.

[0014] The module box in the emergency zone is fitted with a manifold at the bottom, which is connected to all the hydraulic bladders inside the module box. The protective plate has a U-shaped structure and is fixed to the base plate. The base plate is connected to the rope reel via a suspension rope. The rope reel meshes with a rack via a coaxially mounted gear. The rack is connected to the piston rod of the piston transmission mechanism.

[0015] Among them, the piston tube of the piston transmission mechanism is connected to the connecting pipe through the transition pipe, and the other end of the connecting pipe is connected to the manifold. The rope reel is mounted on the rotating shaft, which is mounted on the shaft bracket via bearings. The shaft bracket is fixed to the bottom surface of the second partition. One end of the hoisting rope is connected to the rope reel, and the other end is connected to the lifting seat on the base plate.

[0016] The connecting tube has threaded joints at both ends, and the diaphragm inside the connecting tube has a groove in the middle.

[0017] The bottom plate has a stop block on its side, the bottom of the second partition plate has a positioning seat, the positioning seat has a spring pin, the end of the spring pin has a ferromagnetic end block, and the side of the positioning seat has an electromagnetic seat that cooperates with the ferromagnetic end block.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention dynamically adjusts the preload distribution through a hydraulic bladder in the battery cell, enabling the battery pack to adapt to the volume changes of the cells during charging and discharging in real time. This effectively suppresses expansion and deformation, reduces internal stress concentration and structural deformation, thereby significantly improving battery safety and lifespan. It employs a closed-loop control system with multi-sensor fusion, including pressure, temperature, and impact sensing units, to control the mechanical pressure of the hydraulic bladder. This ensures precise adjustment and rapid response of the preload provided by the hydraulic bladder, optimizes electrical contact between cells, reduces contact resistance, and improves energy efficiency.

[0019] 2. Through the coordinated design of the hydraulic bladder and emergency protection mechanism, a rigid protection mechanism can be quickly activated when an impact is detected. The protection plate is lifted and locked by hydraulic drive, providing immediate protection for the battery cells and greatly enhancing the impact resistance of the battery pack under extreme conditions.

[0020] 3. The intelligent decision-making layer of the hydraulic control system of this invention is based on a multi-objective optimization algorithm. It combines the SOC, temperature and expansion pressure of the battery cell to dynamically adjust the preload of each zone, thereby achieving differentiated mechanical constraints. This avoids battery cell damage caused by excessive tightness and prevents poor contact caused by excessive looseness. The piezoelectric pump and regulating valve of the execution layer have high precision and fast response characteristics, ensuring the real-time performance and stability of the preload adjustment. Attached Figure Description

[0021] Figure 1 This is a first schematic diagram of the overall structure of the battery pack of the present invention.

[0022] Figure 2 This is a second schematic diagram of the overall structure of the battery pack of the present invention.

[0023] Figure 3 This is a schematic diagram of the bottom shell and partition structure of the battery pack of the present invention.

[0024] Figure 4 This is a schematic diagram of the battery cell module structure of the present invention.

[0025] Figure 5 This is a first schematic diagram of the module box and protective plate structure of the present invention.

[0026] Figure 6 This is a second schematic diagram of the module box and protective plate structure of the present invention.

[0027] Figure 7 This is a schematic diagram showing the location of the hydraulic bladder structure of the present invention.

[0028] Figure 8 This is a schematic diagram showing the location of the hydraulic bladder and protective plate structure of the present invention.

[0029] Figure 9 This is a schematic diagram of the protective plate lifting structure of the present invention.

[0030] Figure 10 This is an internal schematic diagram of the connecting pipe structure of the present invention.

[0031] Figure 11 This is a schematic diagram of the internal structure of the positioning seat of the present invention.

[0032] In the diagram: 1. Bottom shell; 101. First partition; 102. Second partition; 103. Third partition; 104. Limiting groove; 105. Rib; 2. Module box; 3. Sealing cover; 4. Slot; 5. Outer frame; 6. Hydraulic bladder; 7. Battery cell; 8. Diverter pipe; 9. Connector pipe; 10. Oil box; 11. Piezoelectric pump; 12. Piezoelectric regulating valve; 13. Manifold; 14. Base plate; 15. Protective plate; 16. Lifting seat; 17. Piston tube; 18. Piston rod; 19. Rack; 20. Shaft bracket; 21. Gear; 22. Rope reel; 23. Lifting rope; 24. Lifting seat; 25. Transition pipe; 26. Connecting pipe; 27. Diaphragm; 28. Score; 29. ​​Stop; 30. Positioning seat; 31. Spring pin; 32. Ferromagnetic end block; 33. Electromagnetic seat. Detailed Implementation

[0033] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Please see Figures 1 to 11The present invention provides a technical solution: a battery pack with dynamically adjustable preload distribution, which is mainly used in automobiles driven by new energy sources such as plug-in hybrid, pure electric and fuel cell, and can serve as a power source.

[0035] The battery pack includes a battery armor shell consisting of a bottom shell 1 and an upper shell. The bottom shell 1 is provided with a partition structure for the distributed assembly of the cell modules and the control system.

[0036] The partition structure includes a first partition 101, a second partition 102, and a third partition 103, which are installed by screws. The first partition 101 is vertically installed in the bottom shell 1, dividing the installation space of the bottom shell 1 into a control cavity and a cell cavity, for the isolated installation of the control system and the cell module, respectively. The second partition 102 is also horizontally installed in the cell cavity, dividing the cell cavity into upper and lower parts. The upper cavity is the installation position of the cell module, while the lower cavity is the installation position of the emergency protection structure. Furthermore, the third partition 103 is set in the middle of the cell cavity, dividing the cell cavity into two symmetrical parts for the symmetrical installation of two rows of cell modules. At the same time, the third partition 103 forms an installation space in the middle of the cell cavity for the installation of the hydraulic control mechanism.

[0037] Limiting grooves 104 are arranged on the second partition 102 so that the emergency protection mechanism can enter the battery cell module through the limiting grooves 104 to play a protective role.

[0038] A horizontal rib 105 is screwed between the third partition 103 and the inner wall of the bottom shell 1. The rib 105 further divides the upper cavity of the cell chamber into individual slots. The cell module is inserted into the slot. The outer shell of the cell module includes a module box 2 and a sealing cover 3. The module box 2 is connected to the rib 105 by screws, while the sealing cover 3 is fixed to the module box 2 by welding for the protection and installation of the internal components. At the same time, the bottom of the module box 2 is also provided with through slots corresponding to the limiting slots 104, so that the emergency protection mechanism can enter the module box 2.

[0039] The module box 2 has slots 4 evenly spaced on its side wall, through which hydraulic bladders 6 can be distributed and installed. The hydraulic bladders 6 are fitted into an outer frame 5, which is fixed in the slots 4 with screws. The battery cells 7 can be arranged between two adjacent hydraulic bladders 6. Usually, three battery cells 7 are assembled between two hydraulic bladders 6. The hydraulic bladders 6 are filled with incompressible hydraulic oil and connected to a hydraulic control mechanism through pipelines. The hydraulic control mechanism controls the internal pressure of the hydraulic bladders 6, thereby generating a pre-tightening force on the side wall of the battery cells 7. The pre-tightening force refers to the mechanical pressure on the battery cells 7 that keeps them in close contact and stable. It is used to maintain good electrical contact between the battery cells 7, reduce contact resistance, and suppress the volume expansion of the battery cells 7 during charging and discharging, thereby reducing internal stress concentration and structural deformation. Throughout the battery pack's life cycle, the pressure of the hydraulic bladders 6 can be adjusted in real time according to different operating conditions, actively adjusting the magnitude of the mechanical constraint force applied to the battery cells 7 in different areas to adapt to the changing physical state inside the battery.

[0040] Hydraulic bladders 6 in the same battery cell module are connected to the same shunt pipe 8. The shunt pipe 8 is installed on the top of the module box 2 by pipe clamps, and the end of the shunt pipe 8 is connected to a connector pipe 9 by a flange. The connector pipe 9 is a flexible hose and can be connected to the piezoelectric regulating valve 12 by a threaded connector.

[0041] As an embodiment of the present invention, an oil box 10 is fitted into the installation space of the third partition 103, and a piezoelectric pump 11 is connected to the oil box 10. The piezoelectric pump 11 is connected to the piezoelectric regulating valve 12. The oil box 10 is also provided with incompressible hydraulic oil. The piezoelectric pump 11 is a micro hydraulic pump. When the input voltage is applied, it can use the inverse piezoelectric effect of the piezoelectric ceramic to deform the piezoelectric vibrator, and then the deformation generates a change in the volume of the pump chamber to realize the output of hydraulic oil. The hydraulic bladder 6 is pressurized according to the electrical signal.

[0042] The piezoelectric regulating valve 12 adopts a dual-channel structure and is connected to the piezoelectric pump 11 and the oil box 10 respectively. It can control the opening and closing of the two channels according to the electrical signal to achieve precise control of the mechanical pressure of the hydraulic bladder 6.

[0043] A sensing network is installed throughout the battery pack to monitor the overall status of the battery pack and individual cell modules. This network mainly includes piezoresistive thin-film sensors, distributed temperature sensors, and piezoelectric thin-film array sensors. The piezoresistive thin-film sensors are installed on the inner wall of the hydraulic bladder 6 to detect the real-time contact pressure between the hydraulic bladder 6 and the cell 7. The distributed temperature sensors are installed in the middle of the closed cover 3 to detect the local temperature of individual cell modules. The piezoelectric thin-film array sensors are integrated on the inner surfaces of the bottom shell 1 to detect whether the battery pack has been impacted. When impacted, the piezoelectric material generates instantaneous charge signals due to deformation. By analyzing the signal amplitude, frequency, and spatial distribution, the impact location and intensity can be determined.

[0044] Under normal circumstances, the pre-tensioning force generated by the hydraulic bladder 6 is mainly controlled by two parameters: real-time contact pressure and local temperature. This generates dynamically adjusted mechanical pressure for all the battery cells 7 in a single battery cell module. When an impact occurs, the piezoelectric pump 11 and the piezoelectric regulating valve 12 open through the signal from the piezoelectric thin film array sensor, causing the pressure inside the hydraulic bladder 6 to increase rapidly. This causes the emergency protection mechanism below the second partition 102 to be lifted into the module box 2, replacing the hydraulic bladder 6 to provide emergency protection for the battery cells 7.

[0045] As an embodiment of the present invention, a manifold 13 is fitted and installed at the bottom of the module box 2. The manifold 13 is connected to all the hydraulic bladders 6 inside the module box 2, and the hydraulic bladders 6 are connected to the control structure of the emergency protection mechanism through the manifold 13.

[0046] The emergency protection mechanism includes a base plate 14 placed in the bottom shell 1. A protective plate 15 is fixed on the base plate 14 by welding. The protective plate 15 has a U-shaped structure and is inserted into the limiting groove 104. It can enter the module box 2 from the limiting groove 104 and be inserted between the battery cell 7 and the hydraulic bladder 6 to replace the hydraulic bladder 6 for the protection of the side of the battery cell 7.

[0047] A hanger 16 is screwed onto the bottom surface of the second partition 102. A piston tube 17 is clamped inside the hanger 16, and the piston tube 17 contains a piston rod 18. The piston tube 17 can be driven hydraulically. A rack 19 is welded to the outer end of the piston rod 18. Simultaneously, a shaft bracket 20 is screwed onto the bottom surface of the second partition 102. A rotating shaft is mounted on the shaft bracket 20 via bearings. A gear 21 and a rope winding pulley 22 are welded and fixed onto the rotating shaft. The gear 21 and the rope winding pulley 22... The rack 19 is connected, and the end block is installed on the rope winding wheel 22 by welding. The end block is attached to the lifting rope 23, and the other end of the lifting rope 23 is attached to the lifting seat 24 of the base plate 14. Therefore, when the piston rod 18 extends out of the piston tube 17 under hydraulic drive, it can drive the gear 21 and the rope winding wheel 22 to rotate through the rack 19, and then lift the base plate 14 through the lifting rope 23. The protection plate 15 on the base plate 14 can enter the module box 2 to protect the battery cell 7.

[0048] The lifting of the protection plate 15 occurs when the battery pack is subjected to an external impact. A transition pipe 25, which is connected to the piston tube 17 at the end away from the piston rod 18, is welded to it. The transition pipe 25 and the manifold 13 are connected by a connecting pipe 26. Both ends of the connecting pipe 26 are provided with threaded joints, which can be quickly assembled and disassembled. A diaphragm 27 is installed in the cavity of the connecting pipe 26 by welding. The diaphragm 27 is used to seal the connecting pipe 26. Under normal circumstances, the hydraulic oil of the hydraulic bladder 6 will not enter the transition pipe 25 or the piston tube 17. The mechanical pressure of the hydraulic bladder 6 is dynamically controlled by the piezoelectric pump 11. At the same time, the diaphragm 27 has a notch 28 in the middle. When the battery pack is subjected to an impact, the piezoelectric pump 11 can quickly increase the internal pressure of the hydraulic bladder 6 in a short time. After the pressure reaches the pressure that the diaphragm 27 can withstand, the diaphragm 27 can break, allowing the oil to enter the piston tube 17 and generate power to drive the protection plate 15 to lift, providing rigid protection for the battery cell 7.

[0049] As an embodiment of the present invention, a stop block 29 is welded to the side of the base plate 14, and a positioning seat 30 is installed on the bottom surface of the second partition plate 102 by screws. A spring pin 31 is provided in the positioning seat 30 for limiting movement. When an impact occurs and the protection plate 15 is lifted with the base plate 14, the stop block 29 of the base plate 14 is limited by the spring pin 31 after passing through it, thereby keeping the protection plate 15 on the side of the battery cell 7 and providing stable protection. Furthermore, a ferromagnetic end block 32 is welded to the tail end of the spring pin 31, and an electromagnetic seat 33 is assembled on the side of the positioning seat 30 by screws. When the battery pack is inspected after an impact, the electromagnetic seat 33 can be energized to generate an attraction force on the ferromagnetic end block 32, causing the spring pin 31 to retract, releasing the fixation of the base plate 14, and allowing the protection plate 15 to be reset, so as to facilitate the repair work of the hydraulic bladder 6 and the battery cell 7.

[0050] Meanwhile, the connecting tube 26 is installed using a threaded joint, which allows it to be disassembled and replaced if the diaphragm 27 is damaged.

[0051] In use, the invention works as follows: First, the battery pack dynamically adjusts the internal pressure of the hydraulic bladders 6 in each zone via a hydraulic control mechanism. The piezoelectric pump 11 adjusts the hydraulic oil output in real time based on the contact pressure and temperature data of the battery cells 7 fed back by the piezoresistive thin-film sensor and distributed temperature sensor. This allows the hydraulic bladders 6 in different zones to apply differentiated pre-tightening forces to the battery cells 7, suppressing expansion and deformation during charging and discharging and maintaining stable electrical contact. When the piezoelectric thin-film array sensor detects an impact signal, the control system instantly increases the pressure of the corresponding hydraulic bladder 6 to a threshold value, triggering the rupture of the diaphragm 27 in the connecting pipe 26. The hydraulic oil pushes the piston rod 18, which in turn drives the rack and pinion mechanism 21, causing the rope reel 22 to tighten the hoisting rope 23, lifting the protective plate 15 on the base plate 14 to the side of the battery cells 7 to form rigid protection. Simultaneously, the spring pin 31 locks the stop block 29 to maintain the protective state. Throughout the process, the dynamic distribution of the pre-tightening force is controlled in a closed loop through multi-sensor fusion, optimizing the real-time adaptability of the mechanical constraints of the battery cells 7 and providing active safety protection under extreme conditions through hydraulic and mechanical control mechanisms.

[0052] The battery pack's control chamber houses a preload control system, which consists of three parts: a sensing layer, a decision-making layer, and an execution layer. It achieves dynamic adjustment through closed-loop feedback and specifically includes the following components and functional logic: Sensing layer Pressure monitoring unit: Each hydraulic bladder 6 integrates a piezoresistive thin-film sensor on its inner wall to measure the pressure at the contact surface of the battery cell 7 in real time. The measurement range is 0-500kPa and the accuracy is ±1kPa. The output analog signal is converted by AD and then transmitted to the main control chip.

[0053] Temperature monitoring unit: Distributed temperature sensors are embedded in the sealed cover 3 to monitor local temperature, with a measurement range of -40℃ to 120℃ and a resolution of 0.1℃.

[0054] Impact sensing unit: A piezoelectric thin film array is attached to the inner wall of the battery pack. The impact intensity and position coordinates are output through a charge amplifier, with a response time of <2ms.

[0055] decision-making level The main control chip runs a multi-objective optimization algorithm, including: Dynamic pressure mapping model: Based on the three-dimensional lookup table method of SOC, temperature and expansion pressure of cell 7, the optimal preload setting value of each zone is output.

[0056] Impact emergency strategy: Distinguish between slight vibration (10-50Hz) and severe impact (>100Hz) by analyzing the frequency of piezoelectric signals, and determine whether to activate the protection board 15.

[0057] Communication protocol: CAN bus transmits sensor data to BMS, and synchronously receives charging and discharging current and voltage parameters for cross-verification.

[0058] Execution layer Hydraulic drive subsystem: The piezoelectric pump array 11 adjusts the oil output according to the PWM signal, and each pump independently controls 1-4 hydraulic bladders 6.

[0059] The piezoelectric regulating valve 12 (response time 10ms) adopts a double cone valve core structure. The opening degree is adjusted by the duty cycle to achieve pressure fine adjustment with an accuracy of ±0.5kPa.

[0060] Mechanical emergency subsystem: Diaphragm 27 burst control: When the pressure of the hydraulic bladder 6 exceeds the set threshold, usually 250-300kPa, the diaphragm 27 with the notch 28 ruptures, and the oil drives the piston mechanism through the manifold 13.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A battery pack with dynamically adjustable preload distribution, comprising a bottom shell and internal cell modules, characterized in that: The bottom shell is provided with a partition structure to divide the bottom shell space into a control cavity and a cell cavity. The cell cavity is further divided into an upper cell installation area and a lower emergency area. A module box is set up in the cell installation area, and a hydraulic bladder is installed in the slot on its side wall. The hydraulic bladder is filled with incompressible hydraulic oil and connected to a hydraulic control mechanism through pipelines. Cells are arranged between the hydraulic bladders, and the hydraulic bladders apply an adjustable preload to the side wall of the cell. The hydraulic control mechanism includes an oil box, a piezoelectric pump, and a piezoelectric regulating valve. The piezoelectric pump adjusts the pressure of the hydraulic bladder based on sensor data. The battery pack is equipped with a sensing network, including a piezoresistive thin-film sensor on the inner wall of the hydraulic bladder, a distributed temperature sensor on the sealing cover, and a piezoelectric thin-film array sensor on the inner wall of the bottom shell. The emergency zone is equipped with a liftable protection plate, which is connected to the hydraulic bladder via a piston transmission mechanism, a connecting pipe with a diaphragm, and a manifold. When an impact signal is triggered, the piezoelectric pump pressurizes the diaphragm in the connecting pipe, causing the hydraulic oil to drive the piston transmission mechanism and lift the protection plate to the side of the battery cell.

2. A battery pack with dynamically adjustable preload distribution according to claim 1, characterized in that: The partition structure includes a vertically arranged first partition, a horizontally arranged second partition, and a third partition located in the middle of the cell cavity; The upper part of the cell cavity has horizontal ribs in the cell mounting area, which divide the upper cavity into independent slots for inserting cell modules.

3. A battery pack with dynamically adjustable preload distribution according to claim 1, characterized in that: The bottom of the module box is provided with a through groove that corresponds one-to-one with the upper limit groove of the second partition, and the top of the module box is provided with a sealing cover, which is fixed on the module box. The limiting groove on the second partition is used to allow the protection plate to pass through and enter the module box.

4. A battery pack with dynamically adjustable preload distribution according to claim 1, characterized in that: The hydraulic bladder is fitted around the outer frame, and the outer frame is fixed in the slot on the side wall of the module box. Two to four battery cells are arranged between two adjacent hydraulic bladders. All hydraulic bladders in the same battery cell module are connected to the same shunt pipe, which is installed on the top of the module box.

5. A battery pack with dynamically adjustable preload distribution according to claim 4, characterized in that: The end of the diverter pipe is connected to a connector pipe via a flange. The connector pipe is a flexible hose and is connected to a piezoelectric regulating valve via a threaded connector. The oil box of the hydraulic control mechanism is located in the installation space formed by the third partition.

6. A battery pack with dynamically adjustable preload distribution according to claim 1, characterized in that: The piezoelectric regulating valve adopts a dual-channel structure, which is connected to the piezoelectric pump and the oil box respectively, and is used to control the mechanical pressure of the hydraulic bladder.

7. A battery pack with dynamically adjustable preload distribution according to claim 1, characterized in that: The piezoresistive thin-film sensor is used to detect the real-time contact pressure between the hydraulic bladder and the battery cell, the distributed temperature sensor is used to detect the local temperature of a single battery cell module, and the piezoelectric thin-film array sensor is used to sense the impact on the battery pack and locate the impact location and intensity through signal analysis.

8. A battery pack with dynamically adjustable preload distribution according to claim 1, characterized in that: A manifold is fitted into the bottom of the module box in the emergency zone, and the manifold is connected to all the hydraulic bladders inside the module box; The protective plate has a U-shaped structure and is fixed to the base plate. The base plate is connected to the rope reel via a suspension rope. The rope reel meshes with a rack via a coaxially mounted gear. The rack is connected to the piston rod of the piston transmission mechanism.

9. A battery pack with dynamically adjustable preload distribution according to claim 8, characterized in that: The piston tube of the piston transmission mechanism is connected to the connecting pipe through a transition pipe, and the other end of the connecting pipe is connected to the manifold. The rope reel is mounted on the rotating shaft, which is mounted on the shaft bracket via bearings. The shaft bracket is fixed to the bottom surface of the second partition. One end of the hoisting rope is connected to the rope reel, and the other end is connected to the lifting seat on the base plate.

10. A battery pack with dynamically adjustable preload distribution according to claim 9, characterized in that: The connecting tube has threaded joints at both ends, and the diaphragm inside the connecting tube has a groove in the middle.

11. A battery pack with dynamically adjustable preload distribution according to claim 10, characterized in that: The bottom plate has a stop block on the side, the bottom of the second partition plate has a positioning seat, the positioning seat has a spring pin, the end of the spring pin has a ferromagnetic end block, and the side of the positioning seat has an electromagnetic seat that cooperates with the ferromagnetic end block.

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