Battery module restraining force adjusting device and method

Abstract

This invention relates to the field of battery technology and discloses a battery module constraint force adjustment device and method. The battery module constraint force adjustment device includes a clamping assembly, a constraint force adjustment assembly, a constraint force monitoring system, and a controller. The clamping assembly includes a first fixed clamping plate and a sliding clamping plate spaced apart along a first direction. The constraint force adjustment assembly can drive the sliding clamping plate to move closer to and away from the first fixed clamping plate. The first fixed clamping plate and the sliding clamping plate are used to clamp the two ends of the battery module along the first direction. The constraint force monitoring system includes a constraint force acquisition module and a strain acquisition module. The constraint force acquisition module monitors the constraint force of the sliding clamping plate and the first fixed clamping plate on the battery module, and the strain acquisition module monitors the strain of the end face of each battery cell. The constraint force adjustment assembly, the strain acquisition module, and the constraint force acquisition module are all communicatively connected to the controller.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery module constraint force adjustment device and method. Background Technology

[0002] In the power battery and energy storage battery industry, preload is typically applied to battery cells to ensure cycle life. The contact resistance between the cell and the casing generates heat; if this heat cannot dissipate quickly enough, it can lead to overheating and even fire. Applying preload increases the contact area between the cell and the casing, reduces contact resistance, improves heat dissipation, and lowers battery temperature rise. Applying preload to prismatic cells is crucial for ensuring cell safety and stability. Properly applied preload ensures tight contact between the cell and the casing, reduces contact resistance, improves heat dissipation, increases the cell's mechanical strength and vibration resistance, thereby guaranteeing cell performance and lifespan. During battery assembly, the magnitude of the preload must be strictly controlled to avoid safety hazards caused by excessive or insufficient preload.

[0003] During battery module use, with the increase of charge-discharge cycles, the individual battery cells of the battery module gradually expand. This expansion leads to an increase in the overall volume of the battery module, and the constraint force on the entire battery module gradually increases with the expansion of the individual battery cells. Comparisons of capacity decay under constant displacement and constant pressure test conditions for both NCM and LFP batteries show that releasing the increasing expansion force within the battery cells during charge-discharge cycles can slow down the rate of capacity decay and improve battery life. Therefore, in some scenarios, battery modules are equipped with constraint force adjustment devices. When the constraint force on the battery module reaches a limit, the constraint force is adjusted to release the expansion force and improve the battery module's lifespan.

[0004] However, because the expansion of cells within each battery cell is not entirely the same, some cells in a battery cell expand more while others expand less. This uneven expansion may result in some battery cells with more internal expansion experiencing excessively large constraints, even though the overall constraint force on the battery module may not exceed the limit for releasing expansion force. This restricts the normal expansion of the cells in these cells and reduces their lifespan.

[0005] Therefore, there is an urgent need for a battery module constraint force adjustment device and method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a battery module constraint force adjustment device and method, so that the constraint force on each battery cell is within an appropriate range.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A battery module constraint force adjustment device is used for adjusting the constraint force of a battery module. The battery module has two oppositely arranged ends along a first direction. The battery module includes a plurality of battery cells stacked sequentially along the first direction. Each battery cell has two end faces along the first direction. The battery module constraint force adjustment device includes a clamping component, a constraint force adjustment component, a constraint force monitoring system, and a controller.

[0009] The clamping assembly includes a first fixed clamping plate and a sliding clamping plate that are spaced apart;

[0010] The constraint force adjustment component can drive the sliding clamp to move closer to and away from the first fixed clamp, the first fixed clamp and the sliding clamp are used to clamp the two ends of the battery module along the first direction;

[0011] The constraint force monitoring system includes a constraint force acquisition module and a strain acquisition module. The constraint force acquisition module is used to monitor the constraint force of the sliding clamp and the first fixed clamp on the battery module. The strain acquisition module is used to monitor the strain of the end face of each battery cell.

[0012] The constraint force adjustment component, the strain acquisition module, and the constraint force acquisition module are all communicatively connected to the controller.

[0013] As an improvement to the above technical solution, the strain acquisition module includes multiple strain monitoring components, and each of the battery cells is provided with one strain monitoring component.

[0014] As an improvement to the above technical solution, the strain monitoring component includes a strain gauge and a strain acquisition chip. The strain gauge is disposed on one end face of the corresponding battery cell. The strain gauge is electrically connected to the strain acquisition chip, and the strain acquisition chip is communicatively connected to the controller.

[0015] As an improvement to the above technical solution, the battery cell has a side surface that is angled to the end face, and the strain acquisition chip is disposed on the side surface of the battery cell.

[0016] As an improvement to the above technical solution, the strain monitoring component further includes a first flexible circuit board, which connects the strain gauge and the strain acquisition chip.

[0017] A method for adjusting the constraint force of a battery module, comprising adjusting the constraint force of the battery module using the battery module constraint force adjustment device described in any one of the preceding claims, including:

[0018] The controller monitors the strain monitoring value of each battery cell through the strain acquisition module, and determines the rate of change of the strain monitoring value of each battery cell based on the strain monitoring value of each battery cell. The strain monitoring value is the average strain of the end face of the battery cell in one charge-discharge cycle.

[0019] When the number of battery cells whose strain monitoring value change rate is less than the preset strain monitoring value change rate is not less than the preset number of battery cells, the controller controls the constraint force adjustment component to drive the sliding clamp away from the first fixed clamp until the monitoring value of the constraint force acquisition module is equal to the preset constraint force value.

[0020] As an improvement to the above technical solution, the preset number of battery cells is half the number of battery cells in the battery module.

[0021] As an improvement to the above technical solution, the rate of change of the strain monitoring value of each of the battery cells is determined based on the strain monitoring value of each of the battery cells, including:

[0022] At the end of each charge-discharge cycle, the difference between the strain monitoring value of each battery cell in the most recent charge-discharge cycle and the strain monitoring value in the previous charge-discharge cycle is calculated to obtain the rate of change of the strain monitoring value of each battery cell.

[0023] As an improvement to the above technical solution, it also includes:

[0024] Whenever the cumulative number of charge-discharge cycles of the battery module reaches a preset number, the controller controls the constraint force adjustment component to drive the sliding clamp away from the first fixed clamp until the monitoring value of the constraint force acquisition module is equal to the preset constraint force value.

[0025] As an improvement to the above technical solution, it also includes:

[0026] When the monitored value of the constraint force acquisition module is not less than the constraint force limit, the controller controls the constraint force adjustment component to drive the sliding clamp away from the first fixed clamp until the monitored value of the constraint force acquisition module is equal to the preset constraint force value, and the constraint force limit is greater than the preset constraint force value.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The battery module constraint force adjustment device and method of the present invention monitors the strain of each battery cell end face by setting a strain acquisition module. Based on the strain monitoring value of each battery cell end face, the strain monitoring value change rate of each battery cell can be determined. The strain monitoring value change rate reflects the expansion rate of each battery cell. When the expansion rate of some battery cells is too low, it indicates that the constraint force on the cells inside these battery cells is too large. At this time, the controller controls the constraint force adjustment component to reduce the constraint force of the sliding clamp and the first fixed clamp on the battery module to a preset constraint force value, thereby reducing the constraint force on the cells inside these battery cells, so that the constraint force on the cells in each battery cell can be within an appropriate range, thereby improving the service life of the entire battery module. Attached Figure Description

[0029] Figure 1 This is a partial structural diagram of the battery module constraint force adjustment device provided in an embodiment of the present invention. Figure 1 ;

[0030] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0031] Figure 3 This is a partial structural diagram of the battery module constraint force adjustment device provided in an embodiment of the present invention. Figure 2 ;

[0032] Figure 4 This is a partial structural diagram of the battery module constraint force adjustment device and the battery module provided in the embodiments of the present invention. Figure 1 ;

[0033] Figure 5 This is a partial structural diagram of the battery module constraint force adjustment device and the battery module provided in the embodiments of the present invention. Figure 2 ;

[0034] Figure 6 This is a flowchart of the battery module constraint force adjustment method provided in the embodiment of the present invention.

[0035] In the picture:

[0036] 1. Battery module; 11. Battery cell; 111. End face; 112. Side face;

[0037] 2. Clamping assembly; 21. First fixed clamping plate; 22. Sliding clamping plate; 23. Guide rod; 231. Stop part; 24. Second fixed clamping plate; 25. Third fixed clamping plate; 26. First locking nut; 27. Second locking nut;

[0038] 3. Constraint force adjustment assembly; 31. Motor; 32. Drive gear; 33. Lead screw; 34. Driven gear; 35. Bearing;

[0039] 4. Constraint force monitoring system; 41. Constraint force acquisition module; 411. Constraint force sensor; 412. Second flexible circuit board; 42. Strain monitoring component; 421. Strain gauge; 422. Strain acquisition chip; 423. First flexible circuit board;

[0040] 5. Controller;

[0041] X, the first direction. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0043] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0046] like Figures 1-5As shown, this embodiment provides a battery module constraint force adjustment device for adjusting the constraint force of a battery module 1. The battery module 1 has two oppositely arranged ends along a first direction X. The battery module 1 includes multiple battery cells 11 stacked sequentially along the first direction X. Each battery cell 11 has two end faces 111 along the first direction X. The battery module constraint force adjustment device includes a clamping assembly 2, a constraint force adjustment assembly 3, a constraint force monitoring system 4, and a controller 5. The clamping assembly 2 includes a first fixed clamping plate 21 and a sliding clamping plate 22 spaced apart along the first direction X. The force adjustment component 3 can drive the sliding clamp 22 to move closer to and further away from the first fixed clamp 21. The battery module 1 is clamped between the first fixed clamp 21 and the sliding clamp 22. The constraint force monitoring system 4 includes a constraint force acquisition module 41 and a strain acquisition module. The constraint force acquisition module 41 is used to monitor the constraint force of the sliding clamp 22 and the first fixed clamp 21 on the battery module 1. The strain acquisition module is used to monitor the strain of the end face 111 of each battery cell 11. The constraint force adjustment component 3, the strain acquisition module and the constraint force acquisition module 41 are all connected to the controller 5.

[0047] Those skilled in the art will understand that the constraint force on the battery module 1 is the clamping force of the first fixed clamp 21 and the sliding clamp 22 on the battery module 1, and the constraint force on each battery cell 11 in the battery module 1 is equal to the clamping force of the first fixed clamp 21 and the sliding clamp 22 on the battery module 1. Each battery cell 11 includes a casing and a cell inside the casing. As the number of charge-discharge cycles of the battery module 1 increases, the degree of expansion of the cells inside each battery cell 11 is different, resulting in different degrees of expansion of the casings of each battery cell 11. The constraint force on the cells inside the battery cell 11 is equal to the sum of the constraint force on the battery cell 11 and the constraint force generated by the strain of the casing of the battery cell 11. Because the degree of expansion of the casings of each battery cell 11 is different, although each battery cell 11 experiences the same constraint force, the constraint force on the cells inside each battery cell 11 is not the same. When all battery cells 11 are subjected to the same constraint force, the greater the expansion of a cell within a particular battery cell 11 compared to the cells within other battery cells 11, the greater the constraint force on that cell. Therefore, even if the overall constraint force on the battery module 1 does not exceed the constraint force limit required for expansion force release, the constraint force on some battery cells 11 with significantly expanded internal cells may be excessive, thus restricting the normal expansion of these cells. The direct manifestation of this restricted normal expansion of a battery cell 11 is a slowdown or even cessation of the strain rate increase at the end face 111 of that battery cell 11.

[0048] The battery module constraint force adjustment device provided in this embodiment monitors the strain of the end face 111 of each battery cell 11 by setting a strain acquisition module. Based on the strain monitoring value of the end face 111 of each battery cell 11, the strain monitoring value change rate of each battery cell 11 can be determined. The strain monitoring value change rate reflects the expansion rate of each battery cell 11. When the expansion rate of some battery cells 11 is too low, it indicates that the constraint force on the internal cells of these battery cells 11 is too large. At this time, the controller 5 controls the constraint force adjustment component 3 to reduce the constraint force of the sliding clamp 22 and the first fixed clamp 21 on the battery module 1 to a preset constraint force value, thereby reducing the constraint force on the internal cells of these battery cells 11, so that the constraint force on the cells in each battery cell 11 can be within an appropriate range, thereby improving the service life of the entire battery module 1.

[0049] Optionally, such as Figure 4 and Figure 5 As shown, the strain acquisition module includes multiple strain monitoring components 42. Each battery cell 11 is equipped with a strain monitoring component 42. The expansion of each battery cell 11 can be independently monitored through the strain monitoring components 42 that correspond one-to-one with the battery cell 11.

[0050] Furthermore, such as Figure 4 and Figure 5 As shown, the strain monitoring component 42 includes a strain gauge 421 and a strain acquisition chip 422. The strain gauge 421 is disposed on one end face 111 of the corresponding battery cell 11. The strain gauge 421 is electrically connected to the strain acquisition chip 422, and the strain acquisition chip 422 is communicatively connected to the controller 5. The expansion of the battery cell 11 will cause strain on the end face 111 of the battery cell 11. By monitoring the strain on the end face 111 of the battery cell 11 through the strain gauge 421, the expansion of the battery cell 11 can be monitored.

[0051] Those skilled in the art will understand that the two end faces 111 of the same battery cell 11 are subject to the same constraint force, and the strain conditions of the two end faces 111 of the same battery cell 11 are also basically the same. Therefore, it is only necessary to monitor one of the two end faces 111 of the battery cell 11 to accurately reflect the expansion of the battery cell 11. In this embodiment, only one end face 111 of the battery cell 11 is provided with a strain gauge 421, which reduces the cost of the battery module constraint force adjustment device while accurately monitoring the expansion of the battery cell 11.

[0052] Furthermore, such as Figure 4 and Figure 5As shown, the battery cell 11 has a side surface 112 that is angled to the end face 111, and the strain acquisition chip 422 is disposed on the side surface 112 of the battery cell 11. Since the end face 111 of the battery cell 11 needs to bear the constraint force, in order to avoid the strain acquisition chip 422 being damaged by the constraint force, in this embodiment the strain acquisition chip 422 is disposed on the side surface 112 of the battery cell 11.

[0053] Furthermore, such as Figure 4 and Figure 5 As shown, the strain monitoring component 42 also includes a first flexible circuit board 423, which connects the strain gauge 421 and the strain acquisition chip 422. To achieve the connection between the strain acquisition chip 422 and the strain gauge 421, a connection circuit needs to be set between them. Since a portion of this connection circuit is located on the end face 111 of the battery cell 11, this portion of the connection circuit will be subject to pressure from constraint forces. To prevent damage to the connection circuit from pressure, this embodiment utilizes the pressure-resistant properties of the flexible circuit board, employing the first flexible circuit board 423 to connect the strain gauge 421 and the strain acquisition chip 422.

[0054] Optionally, such as Figures 1-5 As shown, the clamping assembly 2 also includes multiple guide rods 23. The first fixed clamping plate 21 and the sliding clamping plate 22 are slidably connected to each guide rod 23, and the multiple guide rods 23 are spaced apart along the circumference of the battery module 1. The guide rods 23 guide the sliding clamping plate 22, so that the sliding clamping plate 22 can better cooperate with the first fixed clamping plate 21 to apply a constraint force to the battery module 1. Specifically, in this embodiment, both the first fixed clamping plate 21 and the sliding clamping plate 22 are rectangular plates. Four guide rods 23 are provided, and the four guide rods 23 are respectively provided at the four apex regions of the first fixed clamping plate 21 and the sliding clamping plate 22. Each of the four apex regions of the first fixed clamping plate 21 and the four apex regions of the sliding clamping plate 22 is provided with a connecting hole. Each guide rod 23 passes through the corresponding connecting hole on the first fixed clamping plate 21 and the sliding clamping plate 22. A stop part 231 is fixedly provided at the top of each guide rod 23. The top surface of the first fixed clamping plate 21 abuts against the stop part 231 at the top of each guide rod 23. A first locking nut 26 is threadedly connected to each guide rod 23. The first locking nut 26 abuts against the bottom surface of the first fixed clamping plate 21. Each apex region of the first fixed clamping plate 21 is clamped and fixed to the top of the corresponding guide rod 23 by the first locking nut 26 and the stop part 231.

[0055] Optionally, such as Figures 1-5As shown, the battery module constraint force adjustment device provided in this embodiment also includes a second fixing plate 24 and a third fixing plate 25. The second fixing plate 24 is fixedly connected to each guide rod 23, and the third fixing plate 25 is fixedly connected to each guide rod 23. Specifically, in this embodiment, the second fixing plate 24 and the third fixing plate 25 are both rectangular plates, and each of the second fixing plate 24 and the third fixing plate 25 is provided with a connection hole corresponding to each guide rod 23. Each guide rod 23 passes through the corresponding connection hole on the second fixing plate 24 and the third fixing plate 25. The four guide rods 23 are respectively located in the four apex regions of the second fixing plate 24 and the third fixing plate 25. Each guide rod 23 is threaded with multiple second locking nuts 27. Each corner of the fixed clamping plate 24 is clamped and fixed to the guide rod 23 by one upper and one lower second locking nut 27. That is, the four corners of the second fixed clamping plate 24 are locked to the four guide rods 23 by a total of eight second locking nuts 27. Similarly, each corner of the third fixed clamping plate 25 is also clamped and fixed to the guide rod 23 by one upper and one lower second locking nut 27. The four corners of the third fixed clamping plate 25 are locked to the four guide rods 23 by a total of eight second locking nuts 27. The second fixed clamping plate 24 is located on the side of the sliding clamping plate 22 away from the first fixed clamping plate 21 and is spaced apart from the sliding clamping plate 22. The third fixed clamping plate 25 is located on the side of the second fixed clamping plate 24 away from the sliding clamping plate 22. The constraint force adjustment assembly 3 is located on the second fixed clamping plate 24 and the third fixed clamping plate 25 and is connected to the sliding clamping plate 22.

[0056] Furthermore, such as Figure 1 and Figure 2As shown, the constraint force adjustment assembly 3 includes a motor 31, a driving gear 32, a driven gear 34, a lead screw 33, and a bearing 35. The motor 31 is fixedly mounted on the third fixed clamping plate 25, and the output shaft of the motor 31 is located on the side of the third fixed clamping plate 25 facing the second fixed clamping plate 24. The driving gear 32 is fixedly connected to the output shaft of the motor 31. The second fixed clamping plate 24 is provided with a threaded hole that passes through the second fixed clamping plate 24 along the first direction X. The lead screw 33 is threadedly connected to the threaded hole on the second fixed clamping plate 24, and both ends are exposed outside the second fixed clamping plate 24. The driven gear 34 is fixed to the end of the lead screw 33 near the third fixed clamping plate 25 and meshes with the driving gear 32. The bearing 35 is fixedly mounted on the sliding clamping plate 22 and is located on the side of the sliding clamping plate 22 facing the second fixed clamping plate 24. The end of the lead screw 33 near the sliding clamping plate 22 is rotatably connected to the sliding clamping plate 22 through the bearing 35. In this embodiment, the root circle diameter of the driving gear 32 is larger than that of the driven gear 34, so that the driving gear 32 to the driven gear 34 has a lower transmission ratio. Since the motor 31 has a high speed, the lower transmission ratio of the driving gear 32 to the driven gear 34 is beneficial to reducing the speed of the lead screw 33.

[0057] When it is necessary to adjust the constraint force of the first fixed clamping plate 21 and the sliding clamping plate 22 on the battery module 1, the motor 31 drives the drive gear 32 to rotate, the drive gear 32 drives the driven gear 34 to rotate, and the driven gear 34 drives the lead screw 33 to rotate relative to the second fixed clamping plate 24. Since the second fixed clamping plate 24 is fixed on each guide rod 23, that is to say, the second fixed clamping plate 24 will not move along the guide rod 23, so that the rotation of the lead screw 33 is converted into the movement of the lead screw 33 along the first direction X. The movement of the first lead screw 33 will drive the sliding clamping plate 22 to move, thereby changing the distance between the sliding clamping plate 22 and the first fixed clamping plate 21, so as to adjust the constraint force of the first fixed clamping plate 21 and the sliding clamping plate 22 on the battery module 1.

[0058] Optionally, such as Figures 1-5 As shown, the constraint force acquisition module 41 includes a constraint force sensor 411 and a second flexible circuit board 412. The constraint force sensor 411 is disposed on the side of the sliding clamp 22 facing the battery module 1, and the second flexible circuit board 412 connects the constraint force sensor 411 to the controller 5. In this embodiment, the constraint force sensor 411 is also a pressure sensor, which monitors the positive pressure between the sliding clamp 22 and the battery module 1. The positive pressure between the sliding clamp 22 and the battery module 1 is also the constraint force of the sliding clamp 22 and the first fixed clamp 21 on the battery module 1. In this embodiment, the flexible circuit board is not afraid of compression. The second flexible circuit board 412 is used to connect the constraint force sensor 411 and the controller 5, and the monitoring data of the constraint force sensor 411 is transmitted to the controller 5 through the second flexible circuit board 412.

[0059] like Figure 6 As shown, this embodiment also provides a battery module constraint force adjustment method. The battery module constraint force adjustment device described above is used to adjust the constraint force of the battery module 1. The method includes: the controller 5 monitors the strain monitoring value of each battery cell 11 through a strain acquisition module, and determines the strain monitoring value change rate of each battery cell 11 based on the strain monitoring value. The strain monitoring value is the average strain of the end face 111 of the battery cell 11 within one charge-discharge cycle. When the number of battery cells 11 with a strain monitoring value change rate less than a preset strain monitoring value change rate is not less than a preset number of battery cells 11, the controller 5 controls the constraint force adjustment component 3 to drive the sliding clamp 22 away from the first fixed clamp 21 until the monitoring value of the constraint force acquisition module 41 equals the preset constraint force value. The preset constraint force value is obtained experimentally. When the constraint force on the battery module 1 equals the preset constraint force value, each battery cell 11 can be in a better working state. In this embodiment, one charge-discharge cycle includes one charge and one discharge.

[0060] The battery module constraint force adjustment method provided in this embodiment can ensure that the constraint force on each cell in each battery cell 11 is within an appropriate range, thereby improving the service life of the entire battery module 1.

[0061] Those skilled in the art will understand that, within the same charge-discharge cycle, the degree of expansion of the battery cell 11 during the charging and discharging process of the battery module 1 is constantly changing. That is to say, the strain of the end face 111 of the battery cell 11 is constantly changing within the same charge-discharge cycle. Therefore, in this embodiment, the average strain of the end face 111 of the battery cell 11 within one charge-discharge cycle is used as the strain monitoring value of the battery cell 11 in that charge-discharge cycle, thereby more comprehensively reflecting the expansion of the battery cell 11 in each charge-discharge cycle.

[0062] Optionally, monitoring the strain of each battery cell 11 includes: within a charge-discharge cycle, collecting the strain value of the end face 111 of each battery cell 11 at regular intervals; at the end of the charge-discharge cycle, calculating the average strain value of each end face 111 of each battery cell 11 within that charge-discharge cycle; the average strain value of each end face 111 of a battery cell 11 within that charge-discharge cycle is also the average strain of the end face 111 of that battery cell 11 within that charge-discharge cycle, and this average strain value is the strain monitoring value of that battery cell 11. The specific value of the unit time interval is set according to experimental data and actual needs.

[0063] Optionally, the preset number of battery cells 11 is half the number of battery cells 11 in the battery module 1. Too few preset battery cells 11 will cause the constraint force adjustment component 3 to operate too frequently, leading to an increased failure rate and affecting the constraint force adjustment effect. Too many preset battery cells 11 will cause the constraint force to be released too late, resulting in some battery cells 11 being in a state of excessive constraint for too long, which is detrimental to improving the lifespan of these battery cells 11. Therefore, considering all factors, in this embodiment, the preset number of battery cells 11 is set to half the number of battery cells 11 in the battery module 1. This provides timely protection for some rapidly expanding battery cells 11 without causing the constraint force adjustment component 3 to operate too frequently.

[0064] Optionally, based on the strain monitoring values ​​of each battery cell 11, the rate of change of the strain monitoring value of each battery cell 11 is determined, including: at the end of each charge-discharge cycle, calculating the difference between the strain monitoring value of the most recent charge-discharge cycle and the strain monitoring value of the previous charge-discharge cycle for each battery cell 11, to obtain the rate of change of the strain monitoring value of each battery cell 11. That is, in this embodiment, the difference between the strain monitoring value of the most recent charge-discharge cycle and the strain monitoring value of the previous charge-discharge cycle is used as the rate of change of the strain monitoring value of that battery cell 11. In other embodiments, the rate of change of the strain monitoring value can also be calculated in other ways.

[0065] Optionally, such as Figure 6 As shown, the battery module constraint force adjustment method provided in this embodiment further includes: when the monitoring value of the constraint force acquisition module 41 is not less than the constraint force limit, the controller 5 controls the constraint force adjustment component 3 to drive the sliding clamp 22 away from the first fixed clamp 21 until the monitoring value of the constraint force acquisition module 41 is equal to the preset constraint force value. The constraint force limit is greater than the preset constraint force value. If the monitoring value of the constraint force acquisition module 41 is not less than the constraint force limit, it indicates that due to the expansion of each battery cell 11, the constraint force on the battery module 1 as a whole has reached the standard for releasing the expansion force. At this time, it is necessary to reduce the constraint force once, reducing the constraint force of the first fixed clamp 21 and the sliding clamp 22 on the battery module 1 to the preset constraint force value. The constraint force limit is specifically set according to experimental data and actual needs.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A battery module constraint force adjustment device for adjusting the constraint force of a battery module (1), wherein the battery module (1) has two oppositely arranged ends along a first direction (X), the battery module (1) includes a plurality of battery cells (11) stacked sequentially along the first direction (X), each battery cell (11) having two end faces (111) along the first direction (X), characterized in that, The battery module constraint force adjustment device includes a clamping component (2), a constraint force adjustment component (3), a constraint force monitoring system (4), and a controller (5); The clamping assembly (2) includes a first fixed clamping plate (21) and a sliding clamping plate (22) arranged at intervals; The constraint force adjustment component (3) can drive the sliding clamp (22) to move closer to and away from the first fixed clamp (21), the first fixed clamp (21) and the sliding clamp (22) are used to clamp the two ends of the battery module (1) along the first direction (X); The constraint force monitoring system (4) includes a constraint force acquisition module (41) and a strain acquisition module. The constraint force acquisition module (41) is used to monitor the constraint force of the sliding clamp (22) and the first fixed clamp (21) on the battery module (1). The strain acquisition module is used to monitor the strain of the end face (111) of each battery cell (11). The constraint force adjustment component (3), the strain acquisition module, and the constraint force acquisition module (41) are all communicatively connected to the controller (5).

2. The battery module constraint force adjustment device according to claim 1, characterized in that, The strain acquisition module includes multiple strain monitoring components (42), and each of the battery cells (11) is provided with one strain monitoring component (42).

3. The battery module constraint force adjustment device according to claim 2, characterized in that, The strain monitoring component (42) includes a strain gauge (421) and a strain acquisition chip (422). The strain gauge (421) is disposed on one end face (111) of the corresponding battery cell (11). The strain gauge (421) is electrically connected to the strain acquisition chip (422), and the strain acquisition chip (422) is communicatively connected to the controller (5).

4. The battery module constraint force adjustment device according to claim 3, characterized in that, The battery cell (11) has a side surface (112) that is angled to the end face (111), and the strain acquisition chip (422) is disposed on the side surface (112) of the battery cell (11).

5. The battery module constraint force adjustment device according to claim 3, characterized in that, The strain monitoring component (42) further includes a first flexible circuit board (423), which connects the strain gauge (421) and the strain acquisition chip (422).

6. A method for adjusting the constraint force of a battery module, characterized in that, Adjusting the constraint force of the battery module (1) using the battery module constraint force adjustment device according to any one of claims 1-5 includes: The controller (5) monitors the strain monitoring value of each battery cell (11) through the strain acquisition module, and determines the strain monitoring value change rate of each battery cell (11) based on the strain monitoring value of each battery cell (11). The strain monitoring value is the average strain of the end face (111) of the battery cell (11) in one charge-discharge cycle. When the number of battery cells (11) whose strain monitoring value change rate is less than the preset strain monitoring value change rate is not less than the preset number of battery cells, the controller (5) controls the constraint force adjustment component (3) to drive the sliding clamp (22) away from the first fixed clamp (21) until the monitoring value of the constraint force acquisition module (41) is equal to the preset constraint force value.

7. The battery module constraint force adjustment method according to claim 6, characterized in that, The preset number of battery cells is half the number of battery cells (11) in the battery module (1).

8. The battery module constraint force adjustment method according to claim 6, characterized in that, Based on the strain monitoring values ​​of each of the battery cells (11), the rate of change of the strain monitoring values ​​of each of the battery cells (11) is determined, including: At the end of each charge-discharge cycle, the difference between the strain monitoring value of each battery cell (11) in the most recent charge-discharge cycle and the strain monitoring value in the previous charge-discharge cycle is calculated to obtain the strain monitoring value change rate of each battery cell (11).

9. The battery module constraint force adjustment method according to claim 6, characterized in that, Also includes: Whenever the cumulative number of charge and discharge cycles of the battery module (1) reaches a preset number, the controller (5) controls the constraint force adjustment component (3) to drive the sliding clamp (22) away from the first fixed clamp (21) until the monitoring value of the constraint force acquisition module (41) is equal to the preset constraint force value.

10. The battery module constraint force adjustment method according to claim 6, characterized in that, Also includes: When the monitoring value of the constraint force acquisition module (41) is not less than the constraint force limit, the controller (5) controls the constraint force adjustment component (3) to drive the sliding clamp (22) away from the first fixed clamp (21) until the monitoring value of the constraint force acquisition module (41) is equal to the preset constraint force value, and the constraint force limit is greater than the preset constraint force value.

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