Battery module swelling force testing device and method

Abstract

The application relates to a battery module expansion force testing device and method, which comprises a support frame, a driving mechanism, an expansion force detection assembly, a displacement and temperature monitoring assembly and a data acquisition system. The support frame comprises a bottom plate, a first fixed plate, a second fixed plate and a movable plate. The first fixed plate and the second fixed plate are fixed on the bottom plate in parallel. The movable plate is movably arranged between the first fixed plate and the second fixed plate. A battery module to be tested is clamped between the first fixed plate and the movable plate. The driving mechanism is drivingly connected with the movable plate. The expansion force detection assembly adopts a thin film pressure sensor array to realize multi-point distributed measurement of expansion force. The displacement and temperature monitoring assembly is used for non-contact and synchronous monitoring of expansion displacement and temperature field distribution of each cell in the battery module to be tested. The data acquisition system is used for synchronous acquisition of measurement data of the expansion force detection assembly and the displacement and temperature monitoring assembly.

Description

Technical Field

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

[0002] With the rapid development of the new energy vehicle industry, increasingly higher requirements are being placed on the energy density, safety performance, and cycle life of power battery systems. As a core component of power battery systems, battery modules are typically composed of multiple cells stacked in series and parallel. During long-term charge-discharge cycles, complex electrochemical reactions occur inside the cells. Factors such as repeated lithium-ion insertion and extraction, the formation and repair of the solid electrolyte interface film, and gas production from side reactions all lead to irreversible expansion of the cell volume. This expansion generates enormous mechanical stress within the module, i.e., expansion force.

[0003] The presence of expansion force poses a serious challenge to the structural integrity and safety of battery modules. Studies have shown that excessive expansion force can lead to deformation of the module end plate, cracking of structural welds, busbar breakage, wrinkling of internal electrode sheets within the cell, and even internal short circuits, potentially resulting in serious safety accidents such as thermal runaway. Therefore, accurately measuring and evaluating the expansion force characteristics under different operating conditions during the battery module development stage is of great significance for optimizing module structural design, assessing cell lifespan, and ensuring system safety.

[0004] Currently, numerous patents have been published regarding battery module expansion force testing devices. Patent CN212871567U discloses a battery module expansion force testing device that measures the expansion force in the stacking direction using a first pressure sensor positioned between the equivalent end plate and the battery module. However, this device, using a traditional pressure sensor, can only measure the resultant force at the ends and cannot obtain information on the expansion force distribution between the cells. Patent CN221325747U discloses a battery module expansion force testing device that achieves expansion force testing for different numbers of battery modules by setting multiple sets of locking holes at equal intervals on fixed crossbeams and fixed longitudinal beams. Patent CN118882876A discloses a battery module expansion force measuring device and expansion force distribution testing method. It uses an adjustment mechanism similar to a crank-connecting rod slider structure to achieve synchronous movement of the two side plates to adjust the size of the test space, and obtains the expansion force distribution using fluorescent materials combined with a CCD imaging system. This method applies visual inspection technology to expansion force distribution testing, but the fluorescence method has high requirements for the testing environment and is difficult to continuously monitor force values.

[0005] In summary, existing technologies share the following common drawbacks: First, they lack simulation of the constraints of the bottom adhesive coating process, neglecting the critical boundary condition of the cell bonding to the liquid cooling plate or casing in the actual battery pack via thermally conductive structural adhesive, leading to a serious disconnect between test data and engineering reality. Second, they primarily rely on end-spoke pressure sensors to measure the resultant force at both ends of the module, failing to obtain the distribution of expansion forces between cells and making it difficult to reveal the internal stress transmission law, especially after the introduction of the bottom adhesive layer, its impact on the internal stress distribution is unknown. Third, they ignore the influence of the stiffness of the module end expansion beam and diaphragm on the system expansion force, which causes the cell to shift due to expansion forces throughout its lifespan. Current methods have significant limitations in measuring cell displacement; traditional displacement sensors are bulky, making it difficult to monitor the displacement of multiple cells simultaneously in a limited space. Fourth, the bottom plate and main body of the test device are often integrated structures, making it difficult to clean and replace the cured adhesive layer when different adhesive layer parameters need to be simulated, severely restricting experimental efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a battery module expansion force testing device and method to solve the above-mentioned technical problems. Therefore, the technical solution adopted by this invention is as follows: According to one aspect of the present invention, a battery module expansion force testing device is provided, comprising: A support frame includes a base plate, a first fixed plate, a second fixed plate, and a movable plate. The first fixed plate and the second fixed plate are fixed to the base plate in parallel with each other. The movable plate is movably disposed between the first fixed plate and the second fixed plate. The battery module to be tested is clamped between the first fixed plate and the movable plate. A drive mechanism, which is drivenly connected to the movable plate; An expansion force detection component, wherein the expansion force detection component uses a thin-film pressure sensor array to realize multi-point distribution measurement of expansion force; A displacement and temperature monitoring component, used for non-contact, synchronous monitoring of the expansion displacement and temperature field distribution of each cell in the battery module under test; and A data acquisition system is provided for simultaneously acquiring measurement data from the expansion force detection component and the displacement and temperature monitoring component.

[0007] In one embodiment, the support frame further includes a guide shaft, the two ends of which are fixed to the first fixed plate and the second fixed plate, respectively. A linear bearing is mounted on the movable plate and is sleeved on the guide shaft.

[0008] In one embodiment, a linear guide module is also mounted on the base plate, and the lower end of the movable plate is fixed on the slider of the linear guide module.

[0009] In one embodiment, a simulated adhesive layer is pre-coated or pasted onto the base plate.

[0010] In one embodiment, insulating spacers are respectively installed on the opposing surfaces of the first fixed plate and the movable plate.

[0011] In one embodiment, the thin-film pressure sensor array is arranged between adjacent cells and between the end cells and the insulating spacer.

[0012] In one embodiment, the driving mechanism includes a lead screw, a bearing housing, and a rocker arm. The bearing housing is fixed to the movable plate. One end of the lead screw is rotatably connected to the bearing housing via a bearing. The second fixed plate is provided with a threaded hole that matches the thread of the lead screw. The lead screw passes through the threaded hole and forms a threaded transmission engagement with the second fixed plate. The rocker arm is fixedly connected to the other end of the lead screw.

[0013] The displacement and temperature monitoring system includes a line laser displacement sensor, multiple displacement measuring plates, and an infrared thermal imager. The line laser displacement sensor is installed on the side of the first fixed plate, with its laser emission direction facing the side of the battery cell of the battery module. The multiple displacement measuring plates are respectively attached to the side of each battery cell and are arranged opposite to the line laser displacement sensor. The infrared thermal imager is fixedly installed on the base plate or on an independent bracket, with its lens aimed at the battery cell array of the battery module.

[0014] In one embodiment, the displacement measuring plate corresponding to the cell closer to the line laser displacement sensor is shorter, while the displacement measuring plate corresponding to the cell farther away from the line laser displacement sensor is longer.

[0015] According to another aspect of the present invention, a method for testing the expansion force of a battery module is also provided, comprising: Provide a battery module expansion force testing device as described above; Battery module installation and debugging: Install the thin-film pressure sensors on the corresponding positions of the large surface of the battery cell and the end spacers; stack the battery cells in sequence, and place the end spacers at both ends; apply glue to the base plate, and place the assembled battery cell stack on the base plate; drive the movable plate to move towards the battery cell stack, so that the end spacers on the inside of the movable plate are in close contact with the ends of the battery cell stack. Calibration and debugging of displacement measurement system: Turn on the line laser displacement sensor, adjust its position and angle so that the laser line can cover all displacement measurement plates, and record the position coordinates of the line segment endpoints of each displacement measurement plate in the initial state as the zero point reference for displacement calculation; turn on the infrared thermal imager, adjust its focal length and field of view to ensure that the temperature distribution of all cells can be clearly captured. Charge / discharge testing and synchronous data acquisition: Connect the battery module to the charge / discharge test cabinet, start the set charge / discharge conditions, and during the charge / discharge process, simultaneously start the data acquisition system, linear laser displacement sensor and infrared thermal imager to record the following data at a preset sampling frequency: The pressure values ​​of each thin-film pressure sensor reflect the distribution of expansion forces between and at the ends of the cells; The position changes of the endpoints of each displacement measuring plate are measured by the line laser displacement sensor, and the lateral expansion displacement of each cell is calculated. Temperature distribution on the surface of each battery cell as measured by an infrared thermal imager; End of test and module disassembly: After the test is completed, rotate the joystick in the opposite direction to move the movable plate backward and release the cell module; remove the base plate together with the cell module attached to it for subsequent analysis or replace the base plate for the next set of experiments.

[0016] The present invention, by adopting the above technical solution, has the following advantages: 1. Realistically simulates bottom adhesive constraint, making test data closer to actual engineering conditions. This invention achieves a realistic simulation of the bottom adhesive coating process inside a battery pack in a laboratory-scale testing facility by setting a detachable base plate and pre-coating or pasting a simulated adhesive layer on the base plate. This design ensures that the test boundary conditions closely match the actual application environment of the battery cell, and the measured expansion force data can accurately reflect the stress state of the battery cell throughout the vehicle's life cycle. In contrast, existing technologies place the battery cell directly on a rigid base plate, ignoring the influence of the adhesive layer constraint on the expansion force transmission path and distribution law, resulting in test results that deviate significantly from engineering reality.

[0017] 2. Thin-film pressure sensor array enables precise measurement of expansion force distribution. This invention abandons the traditional "resultant force" measurement method of end-spoke pressure sensors, and instead adopts a technical solution of arranging a thin-film pressure sensor array between adjacent cells and at the ends. This design achieves full-distribution, high-resolution real-time measurement of expansion forces from the ends to all internal layers, clearly revealing the influence of the bottom adhesive layer constraint on the internal stress transmission law. Existing technologies only measure the resultant force at the ends, failing to obtain this crucial information.

[0018] 3. Single-sensor multi-cell displacement synchronous measurement, compact structure and low cost. This invention employs an innovative solution combining a line laser displacement sensor with a differentiated length displacement measuring plate, achieving the goal of simultaneously measuring the lateral expansion displacement of all battery cells using a single sensor. Compared to traditional solutions that require independently installing point laser sensors on the side of each battery cell, this design completely solves the technical challenge of arranging multiple sensors within a limited space.

[0019] 4. Multi-dimensional data synchronous collection supports in-depth mechanism analysis. This invention integrates the ability to simultaneously measure three dimensions: expansion force distribution, cell displacement, and temperature distribution, providing comprehensive data support for in-depth research on the cell expansion mechanism. By analyzing the intrinsic relationship between these three dimensions, the influence of temperature on expansion behavior, the constitutive relationship between expansion force and deformation, and the changes in the force-displacement response characteristics of the bottom adhesive layer can be revealed.

[0020] 5. The detachable base plate design significantly improves experimental efficiency. The present invention designs the base plate as a detachable structure that is bolted to the fixing plate. When it is necessary to simulate the effect of different types of adhesives, different adhesive layer thicknesses or different coating processes on the expansion force, a new base plate can be quickly replaced simply by unscrewing the connecting bolts, without the need to clean the cured adhesive layer. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the battery module expansion force testing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the arrangement of the thin-film pressure sensor and the battery module according to an embodiment of the present invention; Figure 3 This is a schematic diagram showing the relative positional relationship between the line laser sensor and the displacement measuring plate according to an embodiment of the present invention; Figure 4 This is a flowchart of a battery module expansion force testing method according to an embodiment of the present invention.

[0022] Figure label: 100 - Support frame; 110 - Base plate; 120 - First fixed plate; 130 - Second fixed plate; 140 - Movable plate; 150 - Guide shaft; 160 - Linear bearing; 170 - Linear guide rail; 180 - Slider 200 - Drive mechanism; 210 - Lead screw; 220 - Bearing housing; 230 - Rocker arm; 300 - Expansion force detection component; 310 - Thin-film pressure sensor array; 320 - Insulating septum; 400 - Displacement and temperature monitoring system; 410 - Linear laser displacement sensor; 420 - Displacement measuring plate; 430 - Infrared thermal imager; 500-battery module. Detailed Implementation

[0023] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative of the essential spirit of the technical solution of the present invention.

[0024] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0025] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0026] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0027] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0028] In the following description, in order to clearly demonstrate the structure and working method of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0029] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0030] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] like Figures 1 to 3 As shown, according to one aspect of the present invention, a battery module expansion force testing device is provided. The device includes a support frame 100, a drive mechanism 200, an expansion force detection component 300, a displacement and temperature monitoring component 400, a battery module 500, and a data acquisition system (not shown).

[0032] The support frame 100 is the base of the entire testing device, used to support and fix all other components, and to provide a stable and reliable mechanical reference for the expansion force test. The support frame 100 includes a base plate 110, a first fixed plate 120, a second fixed plate 130, a movable plate 140, multiple guide shafts 150, linear guide rails 170, and a slider 180.

[0033] The base plate 110 features a detachable design with multiple bolt mounting holes, allowing it to be fixedly connected to the bottom of the first fixing plate 120 and the second fixing plate 130 via multiple sets of bolts. The upper surface of the base plate 110 supports the battery module 500 under test, and this surface can be pre-coated with a thermally conductive adhesive layer according to actual testing requirements. The material, thickness, elastic modulus, and shear strength of this thermally conductive adhesive layer can be customized based on the thermally conductive structural adhesive used in actual battery packs, thus realistically simulating the bottom bonding constraints of the battery module in its actual assembly state. The base plate 110 is bolted to the first fixing plate 120 and the second fixing plate 130. When it is necessary to replace the base plate 110 with different adhesive layer parameters or clean residual adhesive, the base plate 110 can be quickly replaced simply by unscrewing the connecting bolts, greatly improving the flexibility and efficiency of experimental operations.

[0034] The first fixing plate 120 is located at one end of the device, serving as the reference positioning end for the battery module 500. The first fixing plate 120 has a rectangular plate structure, and its bottom is fixedly connected to the base plate 110 by bolts to ensure its absolute position remains unchanged during testing. A spacer mounting surface is provided on the side of the first fixing plate 120 facing the battery module 500 for mounting insulating spacers 320. A mounting position for a linear laser displacement sensor 410 is provided on the side of the first fixing plate 120 for fixing and mounting the linear laser displacement sensor 410.

[0035] The second fixing plate 130 is located at the other end of the device, and its overall structure is similar to that of the first fixing plate 120. It is also fixed to the base plate 110 by bolts. The second fixing plate 130 and the first fixing plate 120 are arranged parallel to each other, and the distance between them determines the maximum length of the battery module 500 that the test device can accommodate. A threaded hole is provided at the center of the second fixing plate 130, which forms a threaded transmission engagement with the lead screw 210 in the drive mechanism 200. The side of the second fixing plate 130 facing the battery module 500 is also provided with a spacer mounting surface for mounting the insulating spacer 320 on the other side.

[0036] A movable plate 140 is positioned between the first fixed plate 120 and the second fixed plate 130, and can move along the guide shaft 150 to accommodate battery modules 500 of different sizes. The movable plate 140 has a rectangular plate structure, with linear bearings 160 installed at its four corners. Each linear bearing 160 is slidably engaged with one of the four guide shafts 150. The linear bearings 160 are precision linear bearings with extremely low friction coefficients and excellent radial clearance control, ensuring smooth movement and directional accuracy of the movable plate 140 during movement and preventing skewing or jamming. A bearing seat 220 is fixedly installed at the center of the back of the movable plate 140 (the side facing away from the battery module 500) for rotating connection with the lead screw 210 of the drive mechanism 200. A spacer mounting surface is provided on the side of the movable plate 140 facing the battery module 500 for mounting insulating spacers 320.

[0037] In this embodiment, there are two guide shafts 150, arranged at two corner positions above the movable plate 140. The first fixed plate 120 and the second fixed plate 130 each have corresponding guide shaft mounting holes. The two ends of the guide shafts 150 are inserted into the guide shaft mounting holes of the first fixed plate 120 and the second fixed plate 130, respectively, and are fixedly connected to the two fixed plates by set screws or shaft end retaining rings. The two guide shafts 150 and the two linear guide rail modules are parallel to each other, together forming the linear motion guiding system of the movable plate 140. The linear guide rail module includes a linear guide rail 170 and a slider 180. The lower end of the movable plate 140 is fixed to the slider 180, and the slider 180 can slide along the linear guide rail 170. The guide shafts 150 are processed using precision grinding technology, possessing good surface finish and dimensional stability, ensuring that the motion accuracy of the movable plate 140 will not decrease during long-term use. It should be understood that the guide shafts 150 can also be omitted or other arrangements can be used.

[0038] The drive mechanism 200 is used to adapt to the size of the battery module 500 and adjust the clamping distance between the movable plate 140 and the second fixed plate 130, thereby simulating the constraint state of the battery module 500 in an actual battery pack. The drive mechanism 200 includes a lead screw 210, a bearing seat 220, and a rocker arm 230.

[0039] The lead screw 210 is a transmission rod with precision threads on its shaft. One end of the lead screw 210 is rotatably connected to a bearing housing 220 on the back of the movable plate 140 via a bearing. This bearing can be a thrust ball bearing or an angular contact ball bearing, allowing the lead screw 210 to rotate freely relative to the bearing housing 220, but remaining relatively fixed to the movable plate 140 in the axial direction. The shaft of the lead screw 210 passes through a threaded hole at the center of the second fixed plate 130, and the external thread on the lead screw 210 and the internal thread of the threaded hole in the second fixed plate 130 form a threaded transmission engagement. This threaded pair uses trapezoidal or sawtooth threads, which have high transmission efficiency and good self-locking performance.

[0040] The rocker arm 230 is fixedly connected to the end of the lead screw 210 (i.e., the end extending outward from the second fixed plate 130), and can be a straight rod or a handle design. The rocker arm 230 and the lead screw 210 can be fixedly connected by means of pins, keys, or welding to ensure that the operator can reliably drive the lead screw 210 to rotate synchronously when rotating the rocker arm 230. It should be understood that the rocker arm 230 can also be replaced by a handwheel, etc.

[0041] The working principle of the drive mechanism 200 is as follows: When the operator rotates the rocker arm 230, the rocker arm 230 drives the lead screw 210 to rotate within the threaded hole of the second fixed plate 130. Since the lead screw 210 forms an axially fixed rotational connection with the movable plate 140 through the bearing seat 220, the rotational feed motion of the lead screw 210 within the threaded hole of the second fixed plate 130 is converted into a linear translational motion of the movable plate 140 along the guide shaft 150. When the rocker arm 230 is rotated clockwise, the lead screw 210 feeds towards the first fixed plate 120, pushing the movable plate 140 towards the battery module 500, thereby fixing the battery module 500; when the rocker arm 230 is rotated counterclockwise, the lead screw 210 retracts towards the second fixed plate 130, and the movable plate 140 moves away from the battery module 500. The self-locking characteristic of the thread of the lead screw 210 allows the movable plate 140 to be stably held in the set position without the need for an additional locking device.

[0042] It should be understood that the drive mechanism 200 can also be driven by a motor or by a linear drive mechanism such as an electric actuator.

[0043] The expansion force detection component 300 uses a thin-film pressure sensor array to achieve multi-point distribution measurement of expansion force, abandoning the limitation of traditional end-spoke pressure sensors that can only measure the "resultant force". It can obtain microscopic distribution information of expansion force between cells inside the battery module 500. The expansion force detection component 300 includes a thin-film pressure sensor array 310 and an insulating spacer 320.

[0044] The thin-film pressure sensor array 310 employs an extremely thin, flexible piezoresistive or capacitive sensor, exhibiting excellent flexibility and pressure response characteristics. The sensor's measurement range, sensitivity, linearity, and other parameters are selected based on the expansion force range of the battery module 500 under test.

[0045] The arrangement of the thin-film pressure sensor array 310 is as follows: Between adjacent battery cells, a thin-film pressure sensor 310 is disposed on the large surface of a single battery cell. When adjacent battery cells expand and come into contact with each other during charging and discharging, the thin-film pressure sensor 310 disposed between them can read the expansion force data between the battery cells in real time. The flexible nature of the thin-film pressure sensor 310 allows it to fit tightly against the large surface of the battery cell, accurately sensing pressure changes in various areas of the battery cell surface.

[0046] At the end position, the thin-film pressure sensor 310 is arranged between the insulating spacer 320 and the first fixed plate 120 (or between the insulating spacer 320 and the end cell), and between the insulating spacer 320 and the movable plate 140 (or between the insulating spacer 320 and the end cell). The specific arrangement of the sensor can be flexibly selected according to the testing requirements. The thin-film pressure sensor 310 at the end position is used to measure the expansion force on the upper end face of the battery module 500 in the cell stacking direction (X direction). This data reflects the overall expansion force output of the battery module 500 in the stacking direction.

[0047] All thin-film pressure sensors 310 are connected to the host computer via a multi-channel data acquisition system to achieve real-time, synchronous data acquisition. The data acquisition system should have a sufficient number of channels and sampling frequency to completely record the pressure changes at each measurement point during the charging and discharging process. The sampling frequency of the data acquisition system is preferably not less than 10Hz to fully capture the dynamic changes in expansion force during charging and discharging.

[0048] Insulating spacers 320 are disposed between the first fixed plate 120 and adjacent battery cells, and between the movable plate 140 and adjacent battery cells. The insulating spacers 320 are made of materials with certain elasticity and cushioning properties, such as silicone rubber or foam. The main functions of the insulating spacers 320 include: firstly, uniformly transmitting pressure to prevent the rigid surfaces of the first fixed plate 120 or the movable plate 140 from directly contacting the battery cells, thus avoiding localized stress concentration and protecting the end structure of the battery cells from damage; secondly, providing a certain degree of elastic cushioning, simulating the mechanical characteristics of the buffer pads between the end plates and battery cells in actual use of the battery module 500; and thirdly, providing electrical insulation to prevent electrical safety risks to test personnel or equipment caused by the battery cell casing becoming electrified during testing.

[0049] The displacement and temperature monitoring system 400 is used for non-contact, synchronous monitoring of the expansion displacement of each cell in the battery module 500 and the overall displacement and temperature field distribution of the entire battery module 500. The displacement and temperature monitoring system 400 includes a line laser displacement sensor 410, multiple displacement measuring plates 420, and an infrared thermal imager 430.

[0050] A linear laser displacement sensor 410 is mounted on the side of the first fixed plate 120 and fixedly connected by a dedicated mounting bracket and bolts. Its laser emission direction is towards the side of the battery cell of the battery module 500. Based on the principle of laser triangulation, the linear laser displacement sensor 410 can emit a linear laser beam and receive the reflected light on the target surface, while simultaneously measuring the distance information of multiple points along the laser line direction. The installation position and angle of the linear laser displacement sensor 410 are precisely calibrated to ensure that the emitted laser line extends along the cell arrangement direction of the battery module 500 and perpendicularly illuminates the displacement measuring plate 420 attached to the side of each cell.

[0051] The displacement measuring plate 420 is attached to the side of each cell and positioned opposite the line laser displacement sensor 410. The displacement measuring plate 420 is made of a material with good diffuse reflectance properties, and its surface has uniform high diffuse reflectance characteristics to ensure stable reflection of the line laser and avoid signal loss or interference caused by specular reflection.

[0052] The displacement measuring plates 420 corresponding to each battery cell have different lengths, and their arrangement follows this pattern: the displacement measuring plates 420 corresponding to the battery cells closer to the line laser displacement sensor 410 are shorter, while the displacement measuring plates 420 corresponding to the battery cells farther away from the line laser displacement sensor 410 are longer. This differentiated length design is one of the core innovations of this invention, and its principle is as follows: The laser line emitted by the line laser displacement sensor 410 extends along the cell arrangement direction (laser line direction). Because the displacement measuring plates 420 attached to each cell have different lengths, the reflected light signal received by the line laser displacement sensor 410 appears as multiple discontinuous line segments along the laser line direction. The endpoint of each line segment corresponds to the boundary of the displacement measuring plate 420 of one cell. By pre-calibrating the mapping relationship between the endpoints of each line segment and the corresponding cell number, during the test, the line laser displacement sensor 410 acquires the reflected light signal in real time and analyzes the positional changes of the endpoints of each line segment in the direction perpendicular to the laser line (i.e., the cell expansion direction, Z direction), thereby calculating the expansion displacement of each cell's side in the Z direction.

[0053] Compared to traditional point laser displacement sensor solutions, the displacement measurement solution of this invention has significant advantages: Traditional solutions require the installation of an independent point laser displacement sensor on the side of each battery cell, which not only results in high sensor costs but also leads to extremely limited installation space and layout difficulties due to the limited spacing between battery cells, and the optical paths of each sensor may interfere with each other; In contrast, this invention uses a single line laser displacement sensor 410 in conjunction with a displacement measurement plate 420 of varying lengths to simultaneously measure the lateral expansion displacement of all battery cells. This results in a compact structure, low cost, high measurement efficiency, and all displacement data has strict time synchronization, which is of great value for analyzing the dynamic process of battery module 500 expansion.

[0054] The infrared thermal imager 430 is fixedly mounted on the base plate 110 or an independent bracket. Its lens is aimed at the cell array of the battery module 500, enabling non-contact, real-time monitoring of the temperature distribution on the surface of each cell. The installation position of the infrared thermal imager 430 should ensure that its field of view completely covers the surface of all cells in the battery module 500, and maintain an appropriate measurement distance from the battery module 500 to meet the spatial resolution requirements of the infrared thermal imager 430. The infrared thermal imager 430 is connected to the host computer via a data cable, and the temperature field image data it acquires is synchronized in time with the data from the thin-film pressure sensor array 310 and the line laser displacement sensor 410.

[0055] During battery charging and discharging, different prismatic cells exhibit temperature differences due to variations in internal resistance and heat dissipation. Temperature is a crucial factor influencing the expansion behavior of prismatic cells; higher temperatures exacerbate the expansion rate and amount. By simultaneously recording the temperature changes of each cell using an infrared thermal imager 430, temperature data can be correlated with expansion force and displacement data for analysis, providing multi-dimensional data support for in-depth research into the cell expansion mechanism. For example, by comparing the temperature and corresponding expansion displacement of each cell at the same moment, the influence of temperature on expansion behavior can be quantitatively analyzed; by tracking the temporal evolution of temperature and expansion force in local hotspot areas, potential risk locations of thermo-mechanical coupling failure can be identified.

[0056] like Figure 4 As shown, according to another aspect of the present invention, a method for testing the expansion force of a battery module based on the above-described testing apparatus is also provided. The method includes the following steps: Step S1: Battery Module Installation and Debugging A thin-film pressure sensor array 310 is pre-installed between adjacent cells in the battery module 500 under test, and the leads of each sensor are led out and connected to a multi-channel data acquisition system. At the same time, insulating spacers 320 are installed on both ends of the end cells, and thin-film pressure sensors are arranged between the insulating spacers 320 and the first fixed plate 120 and between the insulating spacers 320 and the movable plate 140.

[0057] Based on the actual dimensions of the battery module 500 to be tested, the adhesive application area of ​​the base plate 110 is determined and adhesive is applied.

[0058] Place the prepared battery module 500 on the upper surface of the base plate 110, ensuring one end is flush against the insulating spacer 320 on the side of the first fixing plate 120. Rotate the rocker arm 230, causing the lead screw 210 to rotate and feed within the threaded hole of the second fixing plate 130, pushing the movable plate 140 along the guide shaft 150 towards the first fixing plate 120 until the insulating spacer 320 on the side of the movable plate 140 is flush against the other end of the battery module 500. Due to the self-locking characteristic of the lead screw 210's thread, the movable plate 140 will remain stably in its current position.

[0059] Displacement measuring plates 420 are attached to the side of each cell. When attaching them, it is necessary to ensure that the lengths of each measuring plate 420 are arranged according to a predetermined pattern: shorter displacement measuring plates 420 are attached to cells closer to the line laser displacement sensor 410, and longer displacement measuring plates 420 are attached to cells farther away from the line laser displacement sensor 410, and there is no mutual obstruction or overlap between the measuring plates 420.

[0060] Step S2: Calibration and debugging of the displacement measurement system Turn on the line laser displacement sensor 410 and adjust its installation angle and focal length so that the emitted line laser uniformly illuminates all displacement measuring plates 420 along the cell arrangement direction. In the initial state before the battery module 500 is charged or discharged, collect the reflected light signal from the line laser displacement sensor 410, identify the initial position of each line segment endpoint in the sensor coordinate system, and establish a mapping relationship between each line segment endpoint and the corresponding cell number. Record the initial position of each line segment endpoint as the displacement zero point, which serves as the reference for subsequent displacement calculations.

[0061] Simultaneously acquire temperature field images from infrared thermal imager 430 to confirm that the initial temperature of each cell is within the preset test start temperature range.

[0062] Step S3: Charge / discharge test and synchronous data acquisition Start the battery charging and discharging equipment to perform preset cycle conditions on battery module 500. Throughout the entire charging and discharging cycle, the data acquisition system synchronously records the following data: The expansion force data from the thin-film pressure sensor array 310 includes the surface pressure distribution between adjacent cells and the expansion force data at the end positions; the displacement data from the line laser displacement sensor 410 includes the displacement of all cells in the direction perpendicular to the large surface of the cells; and the temperature field data from the infrared thermal imager 430 includes temperature distribution images of the surfaces of all cells in the battery module 500.

[0063] Step S4: End of test and module disassembly After the test is completed, stop the charging and discharging equipment, and the data acquisition system will automatically stop recording data. Rotate the rocker arm 230 counterclockwise to retract the lead screw 210 towards the second fixed plate 130, causing the movable plate 140 to move away from the battery module 500 along the guide shaft 150, releasing stress. After the movable plate 140 has retracted a sufficient distance, remove the battery module 500 from the support frame 100. If the thermally conductive adhesive layer coated on the base plate 110 needs to be replaced or cleaned, unscrew the connecting bolts between the base plate 110 and the first fixed plate 120 and the second fixed plate 130, remove the base plate 110 for replacement or cleaning, and then reinstall the base plate 110 to prepare for the next test.

[0064] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A battery module expansion force testing device, characterized in that, include: A support frame includes a base plate, a first fixed plate, a second fixed plate, and a movable plate. The first fixed plate and the second fixed plate are fixed to the base plate in parallel with each other. The movable plate is movably disposed between the first fixed plate and the second fixed plate. The battery module to be tested is clamped between the first fixed plate and the movable plate. A drive mechanism, which is drivenly connected to the movable plate; An expansion force detection component, wherein the expansion force detection component uses a thin-film pressure sensor array to realize multi-point distribution measurement of expansion force; A displacement and temperature monitoring component is used to monitor the expansion displacement and temperature field distribution of each cell in the battery module under test in a non-contact and synchronous manner. as well as A data acquisition system is provided for simultaneously acquiring measurement data from the expansion force detection component and the displacement and temperature monitoring component.

2. The battery module expansion force testing device according to claim 1, characterized in that, The support frame also includes a guide shaft, with its two ends fixed to the first fixed plate and the second fixed plate, respectively. A linear bearing is mounted on the movable plate and is sleeved on the guide shaft.

3. The battery module expansion force testing device according to claim 2, characterized in that, A linear guide module is also installed on the base plate, and the lower end of the movable plate is fixed on the slider of the linear guide module.

4. The battery module expansion force testing device according to claim 1, characterized in that, The base plate is pre-coated or pasted with a simulated adhesive layer.

5. The battery module expansion force testing device according to claim 1, characterized in that, Insulating spacers are respectively installed on the opposing surfaces of the first fixed plate and the movable plate.

6. The battery module expansion force testing device according to claim 5, characterized in that, The thin-film pressure sensor array is arranged between adjacent cells and between the end cells and the insulating spacer.

7. The battery module expansion force testing device according to claim 1, characterized in that, The drive mechanism includes a lead screw, a bearing housing, and a rocker arm. The bearing housing is fixed to the movable plate. One end of the lead screw is rotatably connected to the bearing housing via a bearing. The second fixed plate is provided with a threaded hole that matches the thread of the lead screw. The lead screw passes through the threaded hole and forms a threaded transmission engagement with the second fixed plate. The rocker arm is fixedly connected to the other end of the lead screw.

8. The battery module expansion force testing device according to claim 1, characterized in that, The displacement and temperature monitoring system includes a line laser displacement sensor, multiple displacement measuring plates, and an infrared thermal imager. The line laser displacement sensor is installed on the side of the first fixed plate, with its laser emission direction facing the side of the battery cell of the battery module. The multiple displacement measuring plates are respectively attached to the side of each battery cell and are arranged opposite to the line laser displacement sensor. The infrared thermal imager is fixedly installed on the base plate or on an independent bracket, with its lens aimed at the battery cell array of the battery module.

9. The battery module expansion force testing device according to claim 8, characterized in that, The displacement measuring plate corresponding to the cell closer to the line laser displacement sensor is shorter, while the displacement measuring plate corresponding to the cell farther away from the line laser displacement sensor is longer.

10. A method for testing the expansion force of a battery module, characterized in that, include: Provide a battery module expansion force testing device as described in any one of claims 1 to 9; Battery module installation and debugging: Install the thin-film pressure sensors on the corresponding positions of the large surface of the battery cell and the end spacers; stack the battery cells in sequence, and place the end spacers at both ends; apply glue to the base plate, and place the assembled battery cell stack on the base plate; drive the movable plate to move towards the battery cell stack, so that the end spacers on the inside of the movable plate are in close contact with the ends of the battery cell stack. Calibration and debugging of displacement measurement system: Turn on the line laser displacement sensor, adjust its position and angle so that the laser line can cover all displacement measurement plates, and record the position coordinates of the line segment endpoints of each displacement measurement plate in the initial state as the zero point reference for displacement calculation; turn on the infrared thermal imager, adjust its focal length and field of view to ensure that the temperature distribution of all cells can be clearly captured. Charge / discharge testing and synchronous data acquisition: Connect the battery module to the charge / discharge test cabinet, start the set charge / discharge conditions, and during the charge / discharge process, simultaneously start the data acquisition system, linear laser displacement sensor and infrared thermal imager to record the following data at a preset sampling frequency: The pressure values ​​of each thin-film pressure sensor reflect the distribution of expansion forces between and at the ends of the cells; The position changes of the endpoints of each displacement measuring plate are measured by the line laser displacement sensor, and the lateral expansion displacement of each cell is calculated. Temperature distribution on the surface of each battery cell as measured by an infrared thermal imager; End of test and module disassembly: After the test is completed, rotate the joystick in the opposite direction to move the movable plate backward and release the cell module; remove the base plate together with the cell module attached to it for subsequent analysis or replace the base plate for the next set of experiments.

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