Pre-tightening fixture for battery assembly and battery assembly pre-tightening method

Abstract

The present application provides a pre-tightening clamp for a battery assembly and a pre-tightening method for a battery assembly, belonging to the technical field of lithium-ion batteries. The pre-tightening clamp includes: a battery accommodating portion; a movable pressure plate located in the battery accommodating portion, wherein the movable pressure plate and the battery accommodating portion define a limited space for accommodating the battery assembly; a thin film pressure sensor group fixed to the lower surface of the movable pressure plate; a gyroscope fixed to the upper surface of the movable pressure plate; a plurality of pushing mechanisms located above the battery accommodating portion and connected to the movable pressure plate, each pushing mechanism being used to move a corner of the movable pressure plate in the up-and-down direction; a data acquisition and processing device, being used to adjust the movement of each corner of the movable pressure plate in the up-and-down direction, so as to achieve a consistent pre-tightening force applied to the battery assembly. The present application can quickly and efficiently achieve a consistent pre-tightening force applied to the battery assembly.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a pre-tightening fixture for a battery assembly and a battery assembly pre-tightening method. Background Art

[0002] Safety accidents of lithium batteries are mainly caused by thermal runaway of the battery safety system. The battery gas continues to accumulate inside the battery pack until the critical opening pressure of the box safety valve is reached. Then the battery gas fills the entire battery compartment, posing a risk of explosion. Therefore, real-time monitoring of the battery cell expansion pressure is very important for early warning of thermal runaway of the battery safety system.

[0003] In order to accurately measure the cell pressure, an initial preload needs to be applied to lithium-ion battery assemblies before leaving the factory. The initial preload applied must ensure that the preload at each location on the battery assembly surface is consistent, so as to facilitate the subsequent accurate and effective evaluation of the expansion behavior of the cell under a certain initial preload.

[0004] The existing method and equipment for applying preload force, such as that disclosed in patent CN116164869A, achieves uniform force on the surface of the battery cell by setting multiple fasteners and fine-tuning the fasteners. However, the equipment used in the prior art is relatively simple, and the fine-tuning control accuracy of the fasteners is limited, making it difficult to achieve uniform force. Summary of the invention

[0005] The object of the present invention is to provide a pre-tightening clamp for a battery assembly and a pre-tightening method for a battery assembly to solve at least one of the above-mentioned technical problems.

[0006] In a first aspect of the present application, a pre-tightening clamp for a battery assembly is provided, the pre-tightening clamp comprising: a battery receiving portion;

[0007] A movable pressing plate in the battery receiving portion, wherein the movable pressing plate and the battery receiving portion define a limited space for receiving a battery assembly;

[0008] A thin film pressure sensor group fixed on the lower surface of the movable pressure plate, the thin film pressure sensor group is used to measure the pressure distribution on the surface of the battery assembly;

[0009] A gyroscope fixed on the upper surface of the movable pressing plate, the gyroscope being used to measure the tilt angle of the battery assembly;

[0010] A plurality of pushing mechanisms located above the battery accommodating portion and connected to the movable pressing plate, each pushing mechanism being used to move a corner of the movable pressing plate in an up-down direction;

[0011] The data acquisition and processing device is used to control each pushing mechanism according to the pressure distribution collected by the thin film pressure sensor group and the tilt angle collected by the gyroscope, adjust each corner of the movable pressure plate to move in the up and down directions, and apply a consistent preload to the battery assembly.

[0012] Optionally, the battery accommodating portion comprises a lower fixing plate, an upper fixing plate, and a plurality of fixing rods fixed to the lower fixing plate and the upper fixing plate, and the lower fixing plate is provided with an accommodating groove for accommodating the battery assembly;

[0013] The movable pressing plate is located between the lower fixing plate and the upper fixing plate, and the plurality of fixing rods pass through the movable pressing plate.

[0014] Optionally, each of the pushing mechanisms includes a motor and a lead screw, wherein the lead screw passes through the upper fixed plate and is fixedly connected to a corner of the movable pressure plate, and the motor drives the lead screw to move, thereby driving a corner of the movable pressure plate to move in the up and down directions.

[0015] Optionally, each of the pushing mechanisms further includes a lead screw nut which is passed through the lead screw and fixed on the upper fixed plate. The motor drives the lead screw to rotate, and the lead screw nut drives the movable pressure plate to move in the up and down directions under the action of the rotation of the lead screw.

[0016] Optionally, a groove adapted to the film pressure sensor group is provided on the lower surface of the movable pressing plate, and the film pressure sensor group is pasted in the groove and is flush with the lower surface of the movable pressing plate;

[0017] The gyroscope is fixed to the middle area of ​​the upper surface of the movable pressing plate.

[0018] Optionally, the thin film pressure sensor group includes a plurality of sensing units, and the distribution density of the sensing units in the middle area of ​​the thin film pressure sensor group is greater than the distribution density in the non-middle area;

[0019] The sensing units at the four corner positions in the thin film pressure sensor group are also used to measure the pressure applied by the pushing mechanism.

[0020] In a second aspect of the present application, a battery assembly pre-tightening method is provided, the method being applied to the pre-tightening fixture for the battery assembly described in any one of the embodiments of the present application, the method comprising:

[0021] Step 1, fix the battery assembly in the limited space of the pre-tightening fixture, and make each pushing mechanism in the pre-tightening fixture in a position;

[0022] Step 2: Obtain a preset initialization coefficient;

[0023] Step 3, obtaining the tilt angle of the battery assembly measured in the current state and the pressure at each position on the surface;

[0024] Step 4: When the pressure at any position is outside the standard pressure range, or the inclination angle is outside the standard inclination range, the applied pushing force of each pushing mechanism is calculated based on the inclination angle in the current state, the initialization coefficient and the pressure at each position;

[0025] Step 5, controlling the movement amount of the corresponding pushing mechanism based on the applied pushing force;

[0026] Repeat steps 3 to 5 until the measured pressure at each position on the surface of the battery assembly is within the standard pressure range, and the measured inclination angle is within the standard inclination range.

[0027] Optionally, the initialization coefficients include basic pushing force, single-point pressure correction coefficient, single-point pressure weight and angle correction coefficient.

[0028] Optionally, the calculating the applied pushing force of each pushing mechanism based on the tilt angle in the current state, the initialization coefficient and the pressure at each position includes:

[0029] Calculate the pressure difference between the pressure at each position in the current state and the target pressure;

[0030] Calculate the tilt difference between the current tilt angle and the target tilt angle;

[0031] Calculate the single-point pressure distribution at the corresponding position based on the pressure difference value in the current state and the single-point pressure correction coefficient;

[0032] Calculate the pressure adjustment amount of each pushing mechanism based on the single-point pressure distribution amount at each position in the current state and the single-point pressure weight;

[0033] Calculating an angle adjustment amount based on the tilt difference in the current state and the angle correction coefficient;

[0034] The applied pushing force of each pushing mechanism is calculated based on the basic pushing force, the angle adjustment amount, and the pressure adjustment amount of each pushing mechanism, and the applied pushing force is positively correlated with the basic pushing force, the pressure adjustment amount, and the angle adjustment amount.

[0035] Optionally, the single-point pressure correction coefficient includes a pressure base coefficient and a pressure ratio adjustment coefficient, and the angle correction coefficient includes an angle base coefficient and an angle ratio adjustment coefficient.

[0036] Optionally, the calculating of the single-point pressure distribution at the corresponding position based on the pressure difference value in the current state and the single-point pressure correction coefficient includes:

[0037] If the absolute value of the pressure difference at a certain position does not exceed the deviation threshold, the pressure basic coefficient is used as the pressure adjustment coefficient at the corresponding position;

[0038] If the absolute value of the pressure difference at a certain position is greater than the deviation threshold, the pressure adjustment coefficient at the corresponding position is calculated based on the pressure base coefficient, the pressure ratio adjustment coefficient and the pressure difference at the corresponding position;

[0039] The single-point pressure distribution at the corresponding position is calculated based on the pressure difference value in the current state and the pressure adjustment coefficient at the corresponding position.

[0040] Optionally, the calculating the angle adjustment amount based on the tilt difference in the current state and the angle correction coefficient includes:

[0041] If the absolute value of the tilt difference in the current state does not exceed the deviation angle threshold, the angle basic coefficient is used as the angle adjustment coefficient in the current state;

[0042] If the absolute value of the tilt difference in the current state is greater than the deviation angle threshold, an angle adjustment coefficient is calculated based on the tilt difference, the angle base coefficient and the angle ratio adjustment coefficient;

[0043] The angle adjustment amount is calculated based on the tilt difference in the current state and the angle adjustment coefficient.

[0044] Optionally, the initialization coefficient further includes: a total force adjustment coefficient; before the applied pushing force of each pushing mechanism is calculated based on the basic pushing force, the angle adjustment amount and the pressure adjustment amount of each pushing mechanism, it also includes:

[0045] Calculate the total force in the current state based on the pressure at each position in the current state;

[0046] Calculate the resultant force difference based on the total resultant force in the current state and the target resultant force;

[0047] Calculating a resultant force adjustment amount based on the resultant force difference in the current state and the total resultant force adjustment coefficient;

[0048] The method of calculating the applied pushing force of each pushing mechanism based on the basic pushing force, the angle adjustment amount and the pressure adjustment amount of each pushing mechanism includes: calculating the applied pushing force of each pushing mechanism based on the basic pushing force, the angle adjustment amount, the resultant force adjustment amount and the pressure adjustment amount of each position.

[0049] The pre-tightening clamp for battery assemblies and the pre-tightening method for battery assemblies in the present application adjust the pre-tightening force of the battery assemblies by combining the pressure distribution and the tilt angle by setting a pressure sensor group and a gyroscope, and fine-tune each corner of the movable pressure plate by independently controlling each pushing mechanism, thereby quickly and efficiently applying a consistent pre-tightening force to the battery assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0051] Figure 1 is a schematic diagram of the overall structure of a pre-tightening clamp in one embodiment at a first viewing angle;

[0052] Figure 2 is a schematic diagram of the overall structure of a pre-tightening clamp in one embodiment at a second viewing angle;

[0053] Figure 3 A schematic diagram of a process of pre-tightening a battery assembly in one embodiment;

[0054] Figure 4 It is a flowchart of calculating the pushing force applied by each pushing mechanism based on the tilt angle in the current state, the initialization coefficient and the pressure at each position in one embodiment.

[0055] Explanation of the accompanying drawings: 10, battery accommodating portion; 20, pushing mechanism; 30, movable pressure plate; 40, film pressure sensor group; 50, gyroscope; 11, lower fixing plate; 12, upper fixing plate; 13, fixing rod; 21, motor; 22, lead screw; 23, lead screw nut; 24, pressure head; 200, battery assembly. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0057] All terms (including technical and scientific terms) used in this application have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0058] For example, the terms "first", "second", etc. used in this application are only used to distinguish similar objects and to differentiate the first object from another object, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance.

[0059] This application proposes a pre-tightening fixture for a battery assembly, combined with Figure 1 and Figure 2 As shown, the pre-tightening fixture includes: a data acquisition and processing device (not shown in the figure), a battery accommodating portion 10, a movable pressing plate 30, a film pressure sensor group 40, a gyroscope 50 and a plurality of pushing mechanisms 20. The pre-tightening fixture is used to apply a consistent pre-tightening force to the battery assembly so that each position of the battery assembly is in a uniform stress state, providing a basis for the subsequent accurate and effective evaluation of the expansion behavior of the battery cells in the battery assembly.

[0060] The battery receiving portion 10 has a battery receiving space formed therein for receiving the battery assembly 200. The movable pressing plate 30 is located within the battery receiving portion 10 and further defines the battery receiving space, and can move up and down within the battery receiving portion 10. The movable pressing plate 30 and the battery receiving portion 10 define a limited space for accommodating the battery assembly. The battery assembly 200 is located within the battery receiving space and is further defined within the limited space by the movable pressing plate 30 and the battery receiving portion 10.

[0061] A thin film pressure sensor group 40 is fixed to the lower surface of the movable pressure plate 30, and the thin film pressure sensor group 40 is used to measure the pressure distribution on the surface of the battery assembly 200. The movable pressure plate 30 is located above the battery assembly 200, and moves away from the battery assembly 200 when moving upward; it moves closer to the battery assembly 200 during the downward movement, and when it moves downward to a certain position, its lower surface and / or the thin film pressure sensor group 40 will be attached to the battery assembly 200; thus, the thin film pressure sensor group 40 can measure the pressure distribution on the surface of the battery assembly 200.

[0062] A gyroscope 50 is fixed on the upper surface of the movable pressing plate 30 , and the gyroscope 50 is used to measure the tilt angle of the battery assembly.

[0063] There are multiple push mechanisms 20, which are respectively arranged above the battery accommodating portion 10. Each push mechanism 20 is connected to the movable pressing plate 30 and can independently drive the movable pressing plate 30 in the up and down directions ( Figure 1 Each of the pushing mechanisms 20 is disposed at an edge position above the battery receiving portion 10, and each of the pushing mechanisms 20 independently drives a corner of the movable pressing plate 30 to move in the up and down directions.

[0064] like Figure 1 and Figure 2As shown, the pushing mechanism 20 includes four, the battery receiving portion 10, the movable pressing plate 30 and the battery assembly are all square structures, and each pushing mechanism 20 is respectively arranged at a corner of the upper surface of the battery receiving portion 10. It can be understood that the shape of the battery receiving portion 10 and the movable pressing plate 30 can be set according to the shape of the battery assembly, and the number of the pushing mechanism 20 can also be more or less according to the shape of the battery assembly and actual needs.

[0065] The data acquisition and processing device is used to control each pushing mechanism 20 according to the pressure distribution collected by the thin film pressure sensor group 40 and the tilt angle collected by the gyroscope 50, and adjust each corner of the active pressure plate 30 to move in the up and down direction, so as to achieve the application of a consistent preload force to the battery assembly. Specifically, in addition to collecting the pressure distribution, the movement of each pushing mechanism 20 is independently controlled according to the collected tilt angle, combined with the pressure distribution and the tilt angle, so as to independently adjust the moving distance of each corner of the active pressure plate 30 in the up and down direction, and finally achieve the application of a consistent preload force to each position of the battery assembly, providing a basis for the subsequent accurate and effective evaluation of the expansion behavior of the battery cells in the battery assembly.

[0066] In one embodiment, the battery accommodating portion 10 includes a lower fixing plate 11, an upper fixing plate 12, and a plurality of fixing rods 13 fixed to the lower fixing plate 11 and the upper fixing plate 12. The lower fixing plate 11 is provided with an accommodating groove for accommodating the battery assembly.

[0067] Among them, the lower fixed plate 11 is used to place the battery assembly, and the shape and size of the receiving groove are adapted to the shape and size of the battery assembly, for example, it can be a square receiving groove, and the battery assembly is placed in the receiving groove to reduce shaking. The upper fixed plate 12 is covered above the lower fixed plate 11 and is arranged parallel to the lower fixed plate 11. Through holes or card slots are provided at corresponding positions of the upper fixed plate 12 and the lower fixed plate 11. The fixing rod 13 can fix the upper fixed plate 12 and the lower fixed plate 11 through the through holes or card slots on the upper fixed plate 12 and the lower fixed plate 11. The number of the fixing rods 13 includes multiple, and each fixing rod 13 is vertically connected to the through holes or card slots in the edge areas of the lower fixed plate 11 and the upper fixed plate 12, so as to surround and protect the battery assembly in the limited space.

[0068] The movable pressing plate 30 is located between the lower fixing plate 11 and the upper fixing plate 12, and a plurality of fixing rods 13 are passed through the movable pressing plate 30. The movable pressing plate 30 is also provided with through holes, and each fixing rod 13 passes through a through hole on the movable pressing plate 30, and the size of the through hole is larger than the size of the fixing rod 13, so that the movable pressing plate 30 can move up and down between the upper fixing plate 12 and the lower fixing rod 13.

[0069] like Figure 1 and Figure 2As shown, there are four fixing rods 13 , and the movable pressing plate 30 is provided with a fixing rod through hole at the center position of each side. Each fixing rod 13 is perpendicular to the center position of one side of the lower fixing plate 11 , the movable pressing plate 30 and the upper fixing plate 12 .

[0070] One or more of the components such as the lower fixing plate 11, the upper fixing plate 12, the fixing rod 13, the movable pressing plate 30 in the present application can be precisely processed by CNC and made of lightweight but strong materials such as aluminum alloy or engineering plastics.

[0071] In one embodiment, each pushing mechanism 20 includes a motor 21 and a screw 22. The screw 22 passes through the upper fixed plate 12 and is fixedly connected to a corner of the movable pressure plate 30. The motor 21 drives the screw 22 to move, thereby driving a corner of the movable pressure plate 30 to move in the up and down directions.

[0072] Each pushing mechanism 20 may be a mechanism that includes a motor and can be driven independently. The number of pushing mechanisms 20 may be 4, and each pushing mechanism 20 is located at a corner position of the upper fixed plate 12. A through hole for a lead screw 22 is provided at each corner position of the upper fixed plate 12, and the lead screw 22 of the pushing mechanism extends from the motor 21, passes through the through hole of the lead screw 22, and is fixedly connected to the movable pressing plate 30. The motor can drive the lead screw 22 to move in the up and down directions, or drive the lead screw 22 to rotate, and the movable pressing plate 30 moves in the up and down directions along with the movement of the lead screw 22.

[0073] The lead screw 22 can be fixedly connected to the movable pressing plate 30 through the pressing head 24 of the pushing mechanism 20. The pressing head 24 is sleeved on the end of the lead screw 22 away from the motor 21 and fixed at the corner position of the movable pressing plate 30.

[0074] In one embodiment, each pushing mechanism 20 also includes a screw nut 23 that passes through the screw 22 and is fixed on the upper fixed plate 12. The motor 21 drives the screw 22 to rotate, and the screw nut 23 drives the movable pressure plate 30 to move in the up and down directions under the action of the rotation of the screw 22.

[0075] In this embodiment, the motor 21 can drive the lead screw 22 to rotate, the lead screw 22 is provided with threads, and the lead screw nut 23 is threaded through the lead screw 22 and fixed on the upper fixing plate 12. Specifically, the lead screw nut 23 can be fixed on the upper surface or the lower surface of the upper fixing plate 12, or directly clamped in the lead screw through hole opened on the upper fixing plate 12.

[0076] When the motor 21 drives the lead screw 22 to rotate through the reducer, the lead screw nut 23 is fixed, and the lead screw 22 and the lead screw nut 23 convert the rotational motion into movement in the up and down directions, and the motor 21, the lead screw 22 and the pressure head 24 rise or fall together, thereby driving the movable pressing plate 30 to move in the up and down directions. The lead screw 22 rotates in the aperture space of the pressure head 24, and drives the movable pressing plate 30 to move in the up and down directions during the rotation.

[0077] Optionally, when the motor 21 rotates forward, the lead screw 22 rotates clockwise, and the motor 21, the lead screw 22 and the movable pressing plate 30 move upward accordingly; when the motor 21 rotates reversely, the lead screw 22 rotates counterclockwise, and the motor 21, the lead screw 22 and the movable pressing plate 30 move downward accordingly. Or vice versa, when the motor rotates reversely, the lead screw rotates counterclockwise, and the movable pressing plate 30 moves upward accordingly; when the motor rotates forward, the lead screw rotates clockwise, and the movable pressing plate 30 moves downward accordingly.

[0078] The moving distance of the movable pressing plate 30 in the up-down direction is proportional to the number of rotations of the lead screw 22. The data acquisition and processing device independently controls the forward or reverse rotation of each motor 21. During the rotation of each lead screw 22, the movable pressing plate 30 is pressed by the pressing head 24, so that one corner of the movable pressing plate 30 is finely adjusted in the up-down direction, thereby realizing fine adjustment of the preload force of the battery assembly.

[0079] In one embodiment, a groove matching the thin film pressure sensor group 40 is opened on the lower surface of the movable pressure plate 30, and the thin film pressure sensor group 40 is pasted in the groove and flush with the lower surface of the movable pressure plate 30; the gyroscope 50 is fixed in the middle area of ​​the upper surface of the movable pressure plate 30.

[0080] The thin film pressure sensor group 40 is in the form of a thin sheet, and can be fixed in the groove on the lower surface of the movable pressing plate 30 by applying a suitable adhesive on the back of the thin film pressure sensor group 40. The lower surface of the movable pressing plate 30 in which the thin film pressure sensor group 40 is embedded is substantially flush with the surface of the battery assembly, and the area of ​​the thin film pressure sensor group 40 is adapted to the battery assembly, so that it can cover various positions on the surface of the battery assembly, thereby facilitating the collection of pressure at various positions on the battery surface.

[0081] The back side of the gyroscope 50 can also be fixed to the middle area of ​​the upper surface of the movable pressure plate 30 using a suitable adhesive to facilitate measurement of the tilt state of the movable pressure plate 30. Since the movable pressure plate 30 is pressed onto the battery assembly, the tilt state of the movable pressure plate 30 also reflects the tilt state of the battery assembly.

[0082] In one embodiment, the thin film pressure sensor group includes multiple sensing units, and the distribution density of the sensing units in the middle area of ​​the thin film pressure sensor group is greater than the distribution density in the non-middle area; the sensing units at the four corner positions in the thin film pressure sensor group are also used to measure the pressure applied by the pushing mechanism.

[0083] In this embodiment, each sensor unit is circular or square; each sensor unit together forms a sensor unit array with M rows and N columns, where M and N are both positive integers greater than 1. mn represents the sensor unit in the mth row and nth column of the M×N sensor unit array, or R i Indicates that the sensor unit in the M×N sensor unit array is in the i-th sensor unit according to the preset sorting rule. m=1,2,3...M, n=1,2,3...N, i=1,2,3...M×N.

[0084] Each sensing unit measures the pressure of a position or position area corresponding to the battery surface. In one embodiment, the sensing units can be evenly distributed in the thin film pressure sensor group, and the distance intervals between adjacent sensing units are the same.

[0085] In one embodiment, a first spacing between adjacent sensing units in the middle region of the thin film pressure sensor group is smaller than a second spacing between adjacent sensing units in the edge region. The thin film pressure sensor group is configured such that the sensing units in the middle region are densely distributed overall, while the sensing units in the edge region are sparsely distributed overall. This distribution design helps to provide more intensive monitoring in areas where pressure changes more drastically within the battery assembly.

[0086] Furthermore, the sensing units at the four corners of the thin film pressure sensor group are not only used to measure the pressure conditions at the four corner positions corresponding to the battery surface, but the measured data are also used to reflect the pressure applied to the battery assembly by the corresponding pushing mechanism. The data acquisition and processing device controls each pushing mechanism according to the pressure distribution measured at the four corner positions, thereby improving the efficiency of applying a consistent preload force to the battery assembly.

[0087] The pre-tightening clamp for the battery assembly in the present application has the advantages of reasonable design and easy operation. By setting a pressure sensor group and a gyroscope, the pressure distribution and the tilt angle are combined to adjust the pre-tightening force of the battery assembly. By independently controlling each pushing mechanism to fine-tune each corner of the movable pressure plate, a consistent pre-tightening force can be applied to the battery assembly quickly and efficiently.

[0088] In one embodiment, a battery assembly pre-tightening method is provided. The pre-tightening method in this application can be applied to the pre-tightening fixture in any of the above embodiments. Figure 3 As shown, the preload method includes:

[0089] Step 310, fix the battery assembly in a limited space in the pre-tightening fixture, and put each pushing mechanism in the pre-tightening fixture in a position.

[0090] Specifically, before pre-tightening, the lower fixing plate can be removed from the pre-tightening fixture, and after the battery assembly is placed in the groove of the lower fixing plate, each fixing rod is inserted into the corresponding through hole or slot on the lower fixing plate, and the lower fixing plate is fixed to the pre-tightening fixture again, and each pushing mechanism is in place by adjusting the position of the movable pressing plate. The movable pressing plate in place can just fit on the surface of the battery assembly, or there is a certain initial gap with the surface of the battery assembly, so that the film pressure sensor group on the movable pressing plate is in close contact with the battery surface, and the gyroscope can detect the tilt state of the battery assembly.

[0091] Step 320, obtaining a preset initialization coefficient.

[0092] In this embodiment, the initialization coefficient is a series of pre-set parameters, and the value of the parameter can be a fixed value, or can be a value that changes adaptively according to the actual measurement process. The specific value of the initialization coefficient is determined according to the relevant parameters of the preload fixture and / or the battery.

[0093] For example, the initialization coefficient may include one or more of the basic pushing force F0, the single point pressure correction coefficient k, the single point pressure weight w, the angle correction coefficient k', the total resultant force adjustment coefficient b, and the like.

[0094] The basic pushing force F0 is used to represent the basic adjustment amount applied to the pushing mechanism. The basic pushing force F0 corresponding to each pushing mechanism may be the same or different. The basic pushing force may be formulated according to the relevant parameters of the pushing mechanism and / or the battery and the control accuracy. For example, for each pushing mechanism, the corresponding basic pushing force under each preload adjustment is the same value.

[0095] The single-point pressure correction coefficient k is a correction coefficient set for the pressure measured by the thin film pressure sensor group. The thin film pressure sensor group includes multiple sensing units, and the single-point pressure correction coefficient corrects the pressure on the battery surface measured by each of the sensing units. The single-point pressure correction coefficient can be expressed as a correction matrix / correction vector, and each element in the correction matrix / correction vector is used to correct the pressure at a position on the battery surface measured by one of the corresponding sensing units. The single-point pressure correction coefficient k can be set according to the relevant parameters of the thin film pressure sensor group (such as one or more parameters such as the position of each sensing unit, the conduction efficiency, and the reflected friction).

[0096] The single-point pressure correction coefficient k may be a fixed value or a value that changes dynamically according to the pressure measured by the thin film pressure sensor group.

[0097] For example, the single-point pressure correction coefficient k can be further determined by the pressure base coefficient k0 and the pressure ratio adjustment coefficient a0. The pressure base coefficient k0 and the pressure ratio adjustment coefficient a0 are both fixed values. The pressure base coefficient k0 is the same fixed base number set for the pressure at each location measured by the thin film pressure sensor group. The sensing unit R at each location i The corresponding pressure base coefficients are the same; the pressure ratio adjustment coefficient a0 is the pressure at each location measured by the thin film pressure sensor group and the target pressure P target The same fixed coefficient is set according to the pressure difference between the two.

[0098] Optionally, the pressure measured by the i-th sensor unit is recorded as P i , then the single-point pressure correction coefficient k corresponding to the i-th sensor unit is i = k0+a0×(P i -P target ).

[0099] The single-point pressure weight w is used to reflect the influence of the pressure at each position measured in the thin film pressure sensor group on the overall preload effect, that is, the influence weight of different sensing units on different pushing mechanisms. Taking the above-mentioned M×N sensing unit array as an example, the single-point pressure weight w can be composed of a single weight element w ij The weight array formed is (M×N)×D, where i=1,2,3...M×N, j=1,2,3...D, and D is the number of pushing mechanisms, for example, D=4. ij Indicates the position of the battery surface corresponding to the i-th sensor unit (i.e., position A i ) relative to the influence weight of the j-th pushing mechanism. Among them, each weight element w ij It can be set according to relevant parameters of the preload clamp and relevant parameters of the battery. The closer the distance between the sensor unit and the pushing mechanism is, the greater the influence of the pushing mechanism is, and the larger the value of the corresponding weight element is.

[0100] The angle correction coefficient k' is a correction coefficient set for the tilt angle measured by the gyroscope. The angle correction coefficient k' can be set according to relevant parameters of the gyroscope. Optionally, the angle correction coefficient k' may include correction coefficient components in multiple directions, such as Figure 1 One or more of the X direction, Y direction, and Z direction.

[0101] The angle correction coefficient k' can be a fixed value, or a value that changes dynamically according to the tilt angle h measured by the gyroscope. For example, the angle correction coefficient k' can be further determined by including an angle base coefficient k0' and an angle proportional adjustment coefficient a0'. The angle base coefficient and the angle proportional adjustment coefficient are both fixed values. The angle base coefficient k0' is a fixed base number set for the tilt angle h measured by the gyroscope, and the angle base coefficient components corresponding to the tilt angle in each direction can be the same or different. The angle proportional adjustment coefficient a0' is the angle between the tilt angle h measured by the gyroscope and the target tilt angle h target The same fixed coefficient is set according to the tilt difference between them.

[0102] Alternatively, k' = k0' + a0' × (hh target ).

[0103] For example, the angle correction coefficient includes the correction coefficient components in the X direction and the Y direction. The tilt angle component in the X direction is recorded as h x , the angle correction coefficient component in the X direction is k x , the angle proportional adjustment coefficient component in the X direction is a x ; The tilt angle component in the Y direction is h y , the angle correction coefficient component in the Y direction is k y , the angle proportional adjustment coefficient component in the Y direction is a y , the angle base coefficient components in each direction have the same value k0', and the target tilt angle components in each direction also have the same value h target Then k x = k0'+a x ×(h x -h target );k y = k0'+ a y ×(h y -h target ).

[0104] The total force adjustment coefficient b represents the sum of the pressures measured by the film pressure sensor group at various positions (i.e., the total force F total The total resultant force adjustment coefficient b can be a fixed value.

[0105] Step 330, obtaining the pressure and tilt angle at each position on the surface of the battery assembly measured in the current state.

[0106] In this embodiment, during the first adjustment, the current state is the in-place state; before the expected consistent preload force is reached, the pushing mechanism can be adjusted multiple times by means of closed-loop control, and the state after the latest adjustment is the current state. By continuously monitoring the current state and adjusting the output of the pushing mechanism according to the current state, the control system can achieve closed-loop control. This control method can ensure that the battery assembly always maintains a stable state during the preload process, and ultimately achieves the expected preload effect.

[0107] The signal measured by the thin film pressure sensor group in the pre-tightening clamp can be used to calculate the pressure at each position on the surface of the battery assembly and identify the surface pressure distribution state of the battery assembly in the current state. The signal measured by the gyroscope can be used to calculate the inclination angle of the battery assembly and identify the inclination state of the battery assembly in the current state.

[0108] Step 340 , identifying whether the pressure at each position is within the standard pressure range, and whether the inclination angle is within the standard inclination range. If so, end the application of preload force to the battery assembly; otherwise, execute step 350 .

[0109] In this application, standard pressure intervals and standard tilt intervals are pre-set, and these two intervals are used to evaluate whether the current state of the battery assembly needs to be adjusted. The standard pressure interval refers to the target range of pressure that should be applied to each position on the surface of the battery assembly when a consistent preload is formed; the standard tilt interval refers to the tilt angle range that should be maintained for the overall posture of the battery assembly when a consistent preload is formed.

[0110] If the pressure at a certain position exceeds the range of the standard pressure range, it means that the preload force at that position is too large or too small and needs to be adjusted; if the tilt angle of the battery assembly exceeds the range of the standard tilt range, it means that its posture is unstable and needs to be adjusted. By adjusting the output of each pushing mechanism, the force of the battery assembly can be changed, so that the pressure at that position can gradually approach the center value of the standard pressure range, and the battery assembly can be restored to the range of the standard tilt range, thereby ensuring that the entire battery assembly maintains a stable posture and is subjected to uniform preload.

[0111] The standard pressure intervals corresponding to each position can be the same or different, and the standard tilt intervals in different directions can also be the same or different. The two intervals are obtained by comprehensive consideration of factors such as the specifications of the battery assembly and the parameters and usage requirements of the pre-tightening fixture (such as the material properties, size, and expected use environment of the battery assembly, the measurement accuracy of the thin film pressure sensor group, the measurement accuracy of the gyroscope, etc.).

[0112] Optionally, the positions on the battery surface may be divided according to the distribution of the sensing units, for example, corresponding to the above-mentioned M×N sensing unit array, which is also divided into M×N positions. Position A on the battery surface i With sensor unit R i The position corresponds to the sensor unit R i The measured pressure P i Indicates that it is in the same sorting rule as the sensor unit and is in the i-th position A i The pressure at.

[0113] For example, position A i The corresponding standard pressure range is [P target_i -P0 _i , P target_i +P0 _i ], P target_i Indicates position A i Target pressure at P0 _i Indicates position A i The allowable pressure error at P target_i and P0 _i It can be set according to the actual situation. Optionally, the target pressure at each position and the pressure error allowable value can be the same or different. For example, the target pressure at each position is P target The allowable pressure error is P0, and the corresponding standard pressure range is [P target -P0,P target +P0].

[0114] The tilt angle h may include a tilt angle h in the X direction. x and the inclination angle h in the Y direction y The standard tilt range corresponding to the tilt angle in the X direction is [h target_x -h0 _x , h target_x +h0 _x ],h target_x Indicates the target tilt angle in the X direction, h0 _x Indicates the allowable value of the angle error in the X direction. The standard tilt range corresponding to the tilt angle in the Y direction is [h target_y -h0 _y , h target_y +h0 _y ],h target_y Indicates the target tilt angle in the Y direction, h0 _y Indicates the allowable angle error in the Y direction. target_x 、h0 _x 、h target_y 、h0 _yIt can be set according to the actual situation. Optionally, the target tilt angle and the angle error allowable value in the X direction and the Y direction can be the same or different. For example, the target tilt angle in each direction is h target The allowable angle error is h0, and the standard pressure ranges corresponding to the two directions are [h target -h0, h target_y +h0].

[0115] When it is identified that the pressure at each position is within the standard pressure range and the inclination angle is within the standard inclination range, the application of the preload force to the battery assembly is terminated; otherwise, the following preload calculation and adjustment are performed.

[0116] After completing one pre-tightening adjustment, the data acquisition and processing device will return to execute the above steps 330 and 340, measure the tilt angle of the battery assembly and the pressure tilt angle at each position, and compare them with the corresponding standard range. When the pressure at any position is outside the standard pressure range, or the tilt angle is outside the standard tilt range, the pre-tightening adjustment will continue until the pressure at each position on the surface of the battery assembly measured is within the standard pressure range, and the measured tilt angle is within the standard tilt range.

[0117] The current state is recorded as the state of the tth preload adjustment process (the preload adjustment process in the in-place state is regarded as the first preload adjustment), then the above position A i The pressure at can be expressed as P i (t), the inclination angle in the X direction can be expressed as h x (t), the inclination angle in the Y direction can be expressed as h y (t).

[0118] Step 350 , calculating the applied pushing force of each pushing mechanism based on the tilt angle in the current state, the initialization coefficient and the pressure at each position.

[0119] The applied pushing force F is used to indicate the pre-tightening force that needs to be applied by the pushing mechanism to the surface of the battery assembly. For example, when the applied pushing force is greater than 0 and the larger it is, the greater the pre-tightening force that needs to be applied is, and the greater the amount of downward movement of the movable pressing plate that needs to be controlled is; when the applied pushing force is less than 0, it means that the currently applied pre-tightening force needs to be reduced, and when the applied pushing force is less than 0 and the smaller it is, the greater the amount of upward movement of the movable pressing plate that needs to be controlled is.

[0120] Note the applied push force F j It represents the force that the j-th pushing mechanism needs to apply to the battery surface. The pushing force applied by the j-th pushing mechanism during the t-th preload adjustment process is F j (t). When the pressure P iThe greater the deviation from the standard pressure range, the greater the deviation between the inclination angle and the standard inclination range, and the push force F is applied. j The larger the absolute value of .

[0121] Step 360: Control the movement amount of the corresponding pushing mechanism based on the applied pushing force.

[0122] The movement amount indicates the distance or stroke that the push mechanism in the preload fixture moves in a specific direction under the control system command, such as the distance that the lead screw that controls the push mechanism moves in the up and down directions, or the angle or number of turns. The system can calculate the specific distance or stroke that each push mechanism needs to move based on the relationship between the applied push force and the movement amount.

[0123] The amount of exercise is positively correlated with the absolute value of the applied force. For example, when the applied force F j When it is greater than 0, the jth pushing mechanism is controlled to move downward, and the motor is controlled to reverse; when the pushing force F is applied j When it is less than 0, the j-th pushing mechanism is controlled to move upward, and the motor is controlled to rotate forward.

[0124] After all the pushing mechanisms are controlled to run the corresponding amount of movement, the state of the preload clamp is updated, and the process returns to continue to execute step 320 and step 330. By performing closed-loop feedback control on the pushing mechanism, the correction and adjustment process of the preload force on the battery surface is continuously iterated until it is detected that the preload force on the battery surface meets the consistency requirement.

[0125] The battery assembly pre-tightening method in this application, based on the above-mentioned pre-tightening fixture, continuously measures whether there is a deviation in the pressure at various positions on the battery surface and whether there is a deviation in the tilt angle of the battery. In the case of a deviation, the movement of each pushing mechanism is calculated in combination with the set initialization coefficient to complete a one-time adjustment of the pre-tightening force on the battery surface. Through closed-loop feedback control of each pushing mechanism, the pre-tightening force on the battery surface is corrected and adjusted multiple times, so that the pre-tightening force on the battery surface is continuously approached to consistency, and finally meets the consistency requirements.

[0126] In one embodiment, the initialization coefficients include basic thrust, single point pressure correction coefficient, single point pressure weight and angle correction coefficient. Figure 4 As shown, step 350 includes:

[0127] Step 410, calculating the pressure difference between the pressure at each position in the current state and the target pressure.

[0128] Among them, the target pressure value at each position is P target For example, the i-th position A i Pressure P iWith target pressure P target The pressure difference between i =P i –P target .

[0129] The current state is recorded as the state during the tth preload adjustment process, then the position A in the current state is i The pressure difference at can be expressed as ΔP i (t), ΔP i (t) = P i (t)–P target .

[0130] Step 420, calculating the tilt difference between the tilt angle in the current state and the target tilt angle.

[0131] Among them, the tilt difference Δh=hh target , h is the measured tilt angle. Specifically, the tilt difference can be divided into the tilt difference Δh in the X direction x , the tilt difference in the Y direction Δh y The target inclination angle in each direction is h target For example, Δh x =h x -h target ; Δh y =h y -h target The current state is the state in the tth preload adjustment process, and the tilt difference in the X direction in the current state can be expressed as Δh x (t), the tilt difference in the Y direction can be expressed as Δh y (t), Δh x (t)=h x (t)-h target ; Δh y (t)=h y (t)-h target .

[0132] Step 430, calculating the single-point pressure distribution at the corresponding position based on the pressure difference value in the current state and the single-point pressure correction coefficient.

[0133] The single-point pressure distribution refers to the pressure value that needs to be adjusted at each position of each thin film pressure sensor group in the current state.

[0134] In one embodiment, the single-point pressure distribution can be the product of the pressure difference ΔP at the corresponding position and the single-point pressure correction coefficient k. That is, the single-point pressure distribution at position Ai = k i ×ΔP i, the current state is the state in the tth preload adjustment process, and the single-point pressure distribution at position Ai in the current state = k i ×ΔP i (t).

[0135] Step 440, calculating the pressure adjustment amount of each pushing mechanism based on the single-point pressure distribution amount and the single-point pressure weight at each position in the current state.

[0136] The pressure adjustment amount Fa represents the adjustment amount required by the pressing mechanism based on the dimension of the pressure distribution of the battery assembly at various positions.

[0137] Specifically, since the positional relationships between the various sensing units and the pushing mechanisms are different, the pressure adjustment amounts of the various pushing mechanisms are not necessarily the same.

[0138] The pressure adjustment amount Fa can be the product of the single-point pressure distribution amount at each position and the single-point pressure weight at the corresponding position. The pressure adjustment amount of the j-th pushing mechanism is Fa j ,but , the current state is recorded as the state in the tth preload adjustment process, and the pressure adjustment amount of the jth push mechanism in the current state is .

[0139] Step 450, calculating the angle adjustment amount based on the tilt difference and the angle correction coefficient in the current state.

[0140] The angle adjustment amount Fb represents the adjustment amount required by the pushing mechanism based on the dimension of the tilt condition of the battery assembly. Optionally, the angle adjustment amounts of each pushing mechanism may be the same value.

[0141] The angle adjustment amount Fb may be the product of the tilt difference Δh and the angle correction coefficient k', and specifically, may be the product of the tilt difference and the angle correction coefficient in each direction. x =k x ×Δh x , the angle adjustment component Fb in the Y direction y =k y ×Δh y , Fb=Fb x +Fb y .

[0142] The current state is the state of the t-th preload adjustment process. The angle adjustment amount of each push mechanism in the current state is Fb(t) = Fb x (t)+ Fb y (t) = k x ×Δh x (t)+ k y×Δh y (t).

[0143] In step 460 , the applied pushing force of each pushing mechanism is calculated based on the basic pushing force, the angle adjustment amount, and the pressure adjustment amount of each pushing mechanism.

[0144] In this embodiment, based on the adjustment amount and the basic pushing force in each dimension, the applied pushing force of each pushing mechanism can be calculated. Specifically, the applied pushing force is positively correlated with the basic pushing force F0, the pressure adjustment amount Fa and the angle adjustment amount Fb.

[0145] By introducing parameters such as single-point pressure correction coefficient and single-point pressure weight, it can be flexibly adjusted according to the characteristics and requirements of different battery components, thereby enhancing the applicability and flexibility of the preload clamp; by combining multiple dimensions to calculate the applied pushing force of each pushing mechanism, the applied pushing force of the pushing mechanism can be more accurately controlled, thereby ensuring that the battery components quickly reach a consistent preload force during the preload process, thereby improving the preload efficiency.

[0146] In one embodiment, the single-point pressure correction coefficient includes a pressure base coefficient and a pressure ratio adjustment coefficient, and the angle correction coefficient includes an angle base coefficient and an angle ratio adjustment coefficient.

[0147] Step 430 includes: if the absolute value of the pressure difference at a certain position does not exceed the deviation threshold, the pressure base coefficient is used as the pressure adjustment coefficient at the corresponding position; if the absolute value of the pressure difference at a certain position is greater than the deviation threshold, the pressure adjustment coefficient at the corresponding position is calculated based on the pressure base coefficient, the pressure ratio adjustment coefficient and the pressure difference at the corresponding position; the single-point pressure distribution at the corresponding position is calculated based on the pressure difference under the current state and the pressure adjustment coefficient at the corresponding position.

[0148] In this embodiment, if the pressure difference at a certain position does not exceed the deviation threshold, it means that the pressure at the position is close to the ideal state, so the pressure basic coefficient k0 is directly used as the pressure adjustment coefficient at the corresponding position. The pressure basic coefficient k0 is a constant determined based on experience or experiments, and is used to represent the basic ratio of pressure adjustment under normal circumstances.

[0149] If the pressure difference at a certain position is greater than the deviation threshold, it means that the pressure at that position needs to be adjusted significantly. At this time, based on the pressure base coefficient k0, the pressure proportional adjustment coefficient a0 and the pressure difference ΔP at the corresponding position, the pressure adjustment coefficient at the corresponding position is calculated through a certain algorithm (such as linear interpolation, nonlinear function, etc.). The pressure proportional adjustment coefficient a0 is used to adjust the sensitivity of the pressure adjustment coefficient according to the magnitude of the pressure difference.

[0150] According to the calculated pressure adjustment coefficient and the pressure difference in the current state, the single-point pressure distribution at the corresponding position is calculated through multiplication or other appropriate operations.

[0151] Optionally, the deviation threshold may be the above-mentioned pressure error allowable value P0, and the deviation thresholds at various positions may be the same value P0, or a corresponding pressure error allowable value P0 may be set for each position. _i .

[0152] Position A i The absolute value of the pressure difference at |ΔP i |= |P i – P target |, when |ΔP i |≤P0 _i When position A i The pressure adjustment coefficient at can be the single point pressure correction coefficient k mentioned above i = k0; when |ΔP i |>P0 _i When position A i Pressure regulation coefficient k i = k0+ a0×(P i – P target ). Position A i The single point pressure distribution at k i ×ΔP i .

[0153] Step 450 includes: if the absolute value of the tilt difference in the current state does not exceed the deviation angle threshold, the angle base coefficient is used as the angle adjustment coefficient in the current state; if the absolute value of the tilt difference in the current state is greater than the deviation angle threshold, the angle adjustment coefficient is calculated based on the tilt difference, the angle base coefficient and the angle ratio adjustment coefficient; the angle adjustment amount is calculated based on the tilt difference in the current state and the angle adjustment coefficient.

[0154] In this embodiment, if the tilt difference does not exceed the deviation angle threshold, it means that the tilt state of the battery assembly is close to the ideal state, so the angle basic coefficient k0' is directly used as the angle adjustment coefficient. The angle basic coefficient is a constant determined based on experience or experiment, which is used to represent the basic ratio of angle adjustment under normal circumstances.

[0155] If the tilt difference at a certain position is greater than the deviation angle threshold, it means that the angle of the battery assembly needs to be adjusted more. At this time, based on the angle base coefficient k0', the angle proportional adjustment coefficient a0' and the tilt difference Δh, the angle adjustment amount Fb is calculated through a certain algorithm (such as linear interpolation, nonlinear function, etc.). The angle proportional adjustment coefficient a0' is used to adjust the sensitivity of the angle adjustment coefficient according to the amplitude of the tilt difference.

[0156] According to the calculated angle adjustment coefficient and the tilt difference in the current state, the corresponding angle adjustment amount is calculated through multiplication or other appropriate operations.

[0157] Optionally, the deviation angle threshold may also be the above-mentioned angle error allowable value h0, and the deviation angle thresholds in each direction may be the same value, or the deviation angle thresholds in different directions may not be the same. For example, the deviation angle threshold in the X direction is the above-mentioned h0. _x , the deviation angle threshold in the Y direction is h0 mentioned above _y .

[0158] The angle adjustment coefficient can be the above-mentioned angle correction coefficient k'. When the absolute value of the tilt difference in the X direction |Δh x |=| h x -h target |≤h0 _x When k x = k0', |Δh x |>h0 _x When k x = k0'+a x ×(h x -h target ); When the absolute value of the tilt difference in the Y direction |Δh y |=| h y -h target |≤h0 _y When k y = k0', |Δh y |>h0 _y When k y = k0'+a y ×(h y -h target ).

[0159] The angle adjustment amount Fb can be the sum of the angle adjustment components in each direction, Fb = Fb x + Fb y = k x ×Δh x + k y ×Δh y .

[0160] By introducing the pressure proportional adjustment coefficient and the angle proportional adjustment coefficient, the sensitivity of the pressure adjustment coefficient and the angle adjustment coefficient are dynamically adjusted according to the magnitude of the pressure difference and the tilt difference. This enables a more flexible and precise adjustment strategy to be adopted when facing deviations of different sizes, thereby improving the efficiency and accuracy of the adjustment.

[0161] For positions or tilt angles close to the ideal state, this method directly uses the pressure base coefficient and the angle base coefficient for fine-tuning, thereby avoiding additional errors introduced by over-adjustment, helping to maintain the stability of the system and avoiding large adjustments caused by small deviations.

[0162] Through the above-mentioned refined adjustment steps, the method can more accurately control the pressure distribution at each position and the adjustment amount of the overall tilt angle, which helps to achieve a more uniform and consistent preload effect and improve the quality and reliability of the product.

[0163] The parameters in this application (such as pressure base coefficient, pressure ratio adjustment coefficient, angle base coefficient and angle ratio adjustment coefficient, etc.) can be adjusted and optimized according to actual conditions, so that high adaptability and flexibility can be maintained in different application scenarios, while reducing the difficulty of implementation and maintenance.

[0164] In one embodiment, the initialization coefficient also includes a total resultant force adjustment coefficient; before step 460, the method further includes: calculating the total resultant force in the current state according to the pressure at each position in the current state; calculating the resultant force difference according to the total resultant force in the current state and the target resultant force; calculating the resultant force adjustment amount based on the resultant force difference in the current state and the total resultant force adjustment coefficient. Step 460 includes: calculating the applied pushing force of each pushing mechanism based on the basic pushing force, the angle adjustment amount, the resultant force adjustment amount, and the pressure adjustment amount at each position.

[0165] According to the pressure value at each position, the total force F is calculated by vector synthesis or algebraic summation. total Target force F target Indicates the total force that is expected to be achieved. The initialization coefficient also includes the total force adjustment coefficient b, which converts the total force F total Combined with the preset target force F target Compare and calculate the difference between the two, that is, the resultant force difference ΔF total =F total -F target .

[0166] Based on the resultant force difference ΔF total The resultant force adjustment amount Fc can be calculated by a certain logical operation with the total resultant force adjustment coefficient b. The resultant force adjustment amount Fc represents the adjustment amount required by the pushing mechanism in the dimension of the resultant force. Among them, the resultant force adjustment amount of each pushing mechanism can be the same value. Optionally, Fc=b×ΔF total .

[0167] The current state is the state in the tth preload adjustment process, and the total force in the current state is expressed as F total (t), the difference in the resultant force is expressed as ΔFtotal (t) = F total (t)-F target The resultant force adjustment is expressed as Fc(t) = b×ΔF total (t) = b×(F total (t)-F target ).

[0168] On the basis of considering the basic pushing force F0, the angle adjustment amount Fb, and the pressure adjustment amount Fa, and further combining the resultant force adjustment amount Fc, the final applied pushing force F of each pushing mechanism is comprehensively calculated. The applied pushing force F is positively correlated with the basic pushing force F0, the angle adjustment amount Fb, the pressure adjustment amount Fa, and the resultant force adjustment amount Fc. For example, the applied pushing force of each pushing mechanism is the sum of the corresponding basic pushing force F0, the angle adjustment amount Fb, the pressure adjustment amount Fa, and the resultant force adjustment amount Fc.

[0169] The pushing force applied by the jth pushing mechanism is F j , F j =F0+Fa j +Fb+Fc. The current state is the state in the t-th preload adjustment process, and the pushing force applied by the j-th pushing mechanism in the current state is F j (t), F j (t)=F0+Fa j (t)+Fb(t)+Fc(t).

[0170] Right now .

[0171] By further introducing a total force adjustment coefficient, the present application can further improve the accuracy of the pushing force applied by the pushing mechanism during each preload adjustment, thereby further improving the efficiency of the battery assembly in achieving a consistent preload.

[0172] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0173] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, all of the above embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form to imply that the information constitutes prior art known to those skilled in the art.

Claims

1. A battery assembly pre-tightening method, characterized in that: The method is applied to a pre-tightening fixture for a battery assembly, and the pre-tightening fixture for a battery assembly comprises: A battery receiving portion; A movable pressing plate in the battery receiving portion, wherein the movable pressing plate and the battery receiving portion define a limited space for receiving a battery assembly; A thin film pressure sensor group fixed on the lower surface of the movable pressure plate, the thin film pressure sensor group is used to measure the pressure distribution on the surface of the battery assembly; A gyroscope fixed on the upper surface of the movable pressing plate, the gyroscope being used to measure the tilt angle of the battery assembly; A plurality of pushing mechanisms located above the battery accommodating portion and connected to the movable pressing plate, each pushing mechanism being used to move a corner of the movable pressing plate in an up-down direction; A data acquisition and processing device, used to control each pushing mechanism according to the pressure distribution collected by the thin film pressure sensor group and the tilt angle collected by the gyroscope, and adjust each corner of the movable pressing plate to move in the up and down directions to achieve a consistent preload force applied to the battery assembly; The method comprises: Step 1, fix the battery assembly in the limited space of the pre-tightening fixture, and make each pushing mechanism in the pre-tightening fixture in a position; Step 2: Obtaining a preset initialization coefficient, wherein the initialization coefficient includes one or more of a basic pushing force, a single point pressure correction coefficient, a single point pressure weight, an angle correction coefficient, and a total resultant force adjustment coefficient; Step 3, obtaining the tilt angle of the battery assembly measured in the current state and the pressure at each position on the surface; Step 4: When the pressure at any position is outside the standard pressure range, or the inclination angle is outside the standard inclination range, the applied pushing force of each pushing mechanism is calculated based on the inclination angle in the current state, the initialization coefficient and the pressure at each position; Step 5, controlling the movement amount of the corresponding pushing mechanism based on the applied pushing force; Repeat steps 3 to 5 until the measured pressure at each position on the surface of the battery assembly is within the standard pressure range, and the measured inclination angle is within the standard inclination range.

2. The preloading method according to claim 1, characterized in that: The battery accommodating portion comprises a lower fixing plate, an upper fixing plate, and a plurality of fixing rods fixed to the lower fixing plate and the upper fixing plate, wherein the lower fixing plate is provided with an accommodating groove for accommodating the battery assembly; The movable pressing plate is located between the lower fixing plate and the upper fixing plate, and the plurality of fixing rods pass through the movable pressing plate.

3. The pre-tightening method according to claim 2, characterized in that: Each of the pushing mechanisms includes a motor and a lead screw. The lead screw passes through the upper fixed plate and is fixedly connected to a corner of the movable pressure plate. The motor drives the lead screw to move, thereby driving a corner of the movable pressure plate to move in the up and down directions.

4. The pre-tightening method according to claim 3, characterized in that: Each of the pushing mechanisms also includes a lead screw nut that passes through the lead screw and is fixed on the upper fixed plate. The motor drives the lead screw to rotate, and the lead screw nut drives the movable pressure plate to move in the up and down directions under the action of the rotation of the lead screw.

5. The pre-tightening method according to claim 1, characterized in that: A groove adapted to the film pressure sensor group is formed on the lower surface of the movable pressing plate, and the film pressure sensor group is pasted in the groove and is flush with the lower surface of the movable pressing plate; The gyroscope is fixed to the middle area of ​​the upper surface of the movable pressing plate.

6. The pre-tightening method according to claim 1, characterized in that: The thin film pressure sensor group includes a plurality of sensing units, and the distribution density of the sensing units in the middle area of ​​the thin film pressure sensor group is greater than the distribution density in the non-middle area; The sensing units at the four corner positions in the thin film pressure sensor group are also used to measure the pressure applied by the pushing mechanism.

7. The pre-tightening method according to claim 1, characterized in that: The initialization coefficients include basic thrust force, single point pressure correction coefficient, single point pressure weight and angle correction coefficient; The step of calculating the applied pushing force of each pushing mechanism based on the tilt angle, the initialization coefficient and the pressure at each position in the current state includes: Calculate the pressure difference between the pressure at each position in the current state and the target pressure; Calculate the tilt difference between the current tilt angle and the target tilt angle; Calculate the single-point pressure distribution at the corresponding position based on the pressure difference value in the current state and the single-point pressure correction coefficient; Calculate the pressure adjustment amount of each pushing mechanism based on the single-point pressure distribution amount at each position in the current state and the single-point pressure weight; Calculating an angle adjustment amount based on the tilt difference in the current state and the angle correction coefficient; The applied pushing force of each pushing mechanism is calculated based on the basic pushing force, the angle adjustment amount, and the pressure adjustment amount of each pushing mechanism, and the applied pushing force is positively correlated with the basic pushing force, the pressure adjustment amount, and the angle adjustment amount.

8. The pre-tightening method according to claim 7, characterized in that: The single-point pressure correction coefficient includes a pressure base coefficient and a pressure ratio adjustment coefficient, and the angle correction coefficient includes an angle base coefficient and an angle ratio adjustment coefficient; The calculating of the single-point pressure distribution at the corresponding position based on the pressure difference value in the current state and the single-point pressure correction coefficient includes: If the absolute value of the pressure difference at a certain position does not exceed the deviation threshold, the pressure basic coefficient is used as the pressure adjustment coefficient at the corresponding position; If the absolute value of the pressure difference at a certain position is greater than the deviation threshold, the pressure adjustment coefficient at the corresponding position is calculated based on the pressure base coefficient, the pressure ratio adjustment coefficient and the pressure difference at the corresponding position; The single-point pressure distribution at the corresponding position is calculated based on the pressure difference value under the current state and the pressure adjustment coefficient at the corresponding position; The calculating the angle adjustment amount based on the tilt difference in the current state and the angle correction coefficient includes: If the absolute value of the tilt difference in the current state does not exceed the deviation angle threshold, the angle basic coefficient is used as the angle adjustment coefficient in the current state; If the absolute value of the tilt difference in the current state is greater than the deviation angle threshold, an angle adjustment coefficient is calculated based on the tilt difference, the angle base coefficient and the angle ratio adjustment coefficient; The angle adjustment amount is calculated based on the tilt difference in the current state and the angle adjustment coefficient.

9. The pre-tightening method according to claim 7, characterized in that: The initialization coefficient also includes: a total force adjustment coefficient; before the applied pushing force of each pushing mechanism is calculated based on the basic pushing force, the angle adjustment amount and the pressure adjustment amount of each pushing mechanism, it also includes: Calculate the total force in the current state based on the pressure at each position in the current state; Calculate the resultant force difference based on the total resultant force in the current state and the target resultant force; Calculating a resultant force adjustment amount based on the resultant force difference in the current state and the total resultant force adjustment coefficient; The step of calculating the applied pushing force of each pushing mechanism based on the basic pushing force, the angle adjustment amount and the pressure adjustment amount of each pushing mechanism comprises: The applied pressing force of each pressing mechanism is calculated based on the basic pressing force, the angle adjustment amount, the resultant force adjustment amount, and the pressure adjustment amount at each position.

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