Battery pack coating thickness measurement method

Abstract

A method for measuring the adhesive coating thickness of a battery pack, relating to the field of battery pack manufacturing technology, is used for the precise measurement of the adhesive coating thickness between the module and the housing in a new energy vehicle battery pack. It can be applied to process verification, quality inspection, and production control in the battery pack production process of various new energy vehicles, including passenger cars and commercial vehicles. The method includes steps S1 to S7: S1. Applying stick-shaped adhesive: On the bottom plane of the battery pack housing, a continuous stick-shaped adhesive is applied manually or using an adhesive application device along the length of the battery module. S2. Covering with a separator: A separator is applied to the surface of the stick-shaped adhesive, ensuring the separator completely adheres to the surface of the stick-shaped adhesive to prevent direct contact and adhesion between the adhesive and the battery module. S3. Module placement and pressing: The battery module is precisely placed into the battery pack housing using an auxiliary positioning tool, ensuring close contact between the bottom of the battery module and the separator. The stick-shaped adhesive is then evenly pressed flat.

Description

Technical Field

[0001] This application relates to the field of battery pack manufacturing technology, and in particular to a method for measuring the thickness of adhesive coating on a battery pack. Background Technology

[0002] Adhesive coating thickness is a key process parameter in the connection between the battery pack module and the casing. Whether the adhesive coating thickness is reasonable and uniform directly affects the bonding strength, sealing performance, and overall structural stability of the battery pack. If the adhesive coating thickness is too thin, it will lead to insufficient bonding strength, making it easy for the module and casing to loosen or detach. At the same time, the sealing performance cannot be guaranteed, and external impurities can easily enter. If the adhesive coating thickness is too thick, it will not only waste adhesive and increase production costs, but also cause problems such as incomplete adhesive spreading and insufficient adhesive application area. This will result in uneven gaps between the module and casing, affecting the assembly accuracy of the battery pack. In fact, excessive stress generated during adhesive curing may even cause deformation of the casing or module, further affecting the performance of the battery pack.

[0003] Currently, existing methods for measuring adhesive thickness in battery pack enclosure coating applications have many defects and shortcomings, as detailed below:

[0004] First, the measurement accuracy is poor, with significant errors. Current technologies mostly use coordinate measuring machines (CMMs) to measure the gap between the module and the housing, indirectly estimating the adhesive thickness. However, the CMM measurement process requires fitting the flatness of the housing and module, which is prone to large errors, leading to significant deviations between the measured results and the actual adhesive thickness. Furthermore, during the adhesive application process, the housing itself has a certain elasticity and will deform under the pressure of the module. This deformation generates measurement noise, further interfering with the accuracy of the measurement results, making the data unreliable and unable to accurately reflect the actual gap and adhesive thickness between the module and the housing.

[0005] Secondly, the measurement methods are not intuitive and are cumbersome to operate. Most existing measurement methods are indirect and cannot directly obtain the true data of the adhesive coating thickness. They require complex calculations and conversions to obtain relevant information about the adhesive coating thickness. The operation process is cumbersome, requires high professional skills from operators, and has low measurement efficiency, which cannot meet the needs of rapid testing in large-scale production processes. Summary of the Invention

[0006] This application provides a method for measuring the adhesive thickness of a battery pack, which is used for the accurate measurement of the adhesive thickness between the module and the housing in a new energy vehicle battery pack.

[0007] This application provides a method for measuring the coating thickness of a battery pack, including steps S1 to S7.

[0008] S1. Applying stick-shaped glue: On the bottom plane of the battery pack box, along the length of the battery module, apply a continuous stick-shaped glue line manually or using a glue application device.

[0009] S2. Separator Covering: A separator is placed over the surface of the stick-shaped adhesive to ensure that the separator completely adheres to the surface of the stick-shaped adhesive, thus preventing the adhesive from directly contacting and sticking to the battery module.

[0010] S3. Module placement and adhesive pressing: Using an auxiliary positioning tool, accurately place the battery module into the battery pack box, ensuring that the bottom of the battery module is in close contact with the separator. Apply even pressure to the stick-shaped adhesive and flatten it.

[0011] S4. Module Removal: After maintaining the battery module under the pressure of the adhesive for a certain period of time, remove the battery module from the battery pack box using an auxiliary tool. At this time, the stick-shaped adhesive has been pressed into a uniform adhesive layer, and the adhesive layer is bonded to the separator.

[0012] S5. Adhesive layer thickness measurement: Remove the adhesive layer from the release liner, use calipers to measure the adhesive layer at multiple points, and record the adhesive layer thickness data at each measurement point.

[0013] S6. Data processing and analysis: The adhesive layer thickness data of all measurement points are processed and analyzed. The maximum value among all measurement data is taken as the actual gap value between the battery module and the battery pack housing. This gap value is the target adhesive thickness for subsequent wide-width adhesive application.

[0014] S7. Wide-width full-area adhesive coating: Based on the target adhesive coating thickness obtained in S6, wide-width full-area adhesive coating is applied to the bottom plane of the battery pack housing. The adhesive coating thickness is controlled within the range of ±0.1mm of the target adhesive coating thickness to complete the battery pack adhesive coating process.

[0015] The battery pack adhesive thickness measurement method in this application solves the problems of large indirect measurement errors and cumbersome operation in existing technologies by using a roller-shaped adhesive extrusion → adhesive layer thickness measurement → target thickness determination → wide-width adhesive application. It directly simulates the gap between the module and the housing using the roller-shaped adhesive, converting the gap into a directly measurable adhesive layer thickness, which is intuitive and accurate. Taking the maximum measured value as the target adhesive thickness ensures that the subsequent wide-width adhesive application completely covers the maximum gap, avoiding problems such as weak adhesion and sealing failure caused by excessively large local gaps. At the same time, it simplifies the operation process, improves measurement efficiency, and adapts to the needs of large-scale production.

[0016] In some embodiments of this application, a preparation step is also included, which precedes S1. The preparation step includes the preparation and inspection of the battery pack housing, battery module, measuring adhesive, separator, calipers, and auxiliary positioning tools.

[0017] By preparing and inspecting all relevant components such as the battery pack housing, modules, adhesives, and calipers, problems such as surface oil stains, damage, dimensional deviations, and tool inaccuracies (e.g., uncalibrated calipers or abnormal adhesive viscosity) can be eliminated in advance. This avoids measurement errors and operational malfunctions (e.g., uneven adhesive application or adhesive layer damage) caused by insufficient preparation in the early stages, further improving the reliability of measurement data and reducing rework rates.

[0018] In some embodiments of this application, in step S2, the separator film can be made of polyethylene, and the edge of the separator film extends at least 5 mm beyond the edge of the adhesive along the length of the battery module.

[0019] The release liner is made of polyethylene. Utilizing its excellent anti-stick properties, flexibility, and low cost, it can effectively prevent the adhesive from sticking to the module, ensuring smooth module removal and intact adhesive layer preservation, while also controlling measurement costs. The release liner is required to extend at least 5mm beyond the adhesive edge to completely cover the adhesive, preventing the adhesive from being exposed and sticking to the module, avoiding damage to the adhesive layer, and ensuring the smooth progress of subsequent thickness measurements.

[0020] In some embodiments of this application, in step S3. module insertion and pressing, a positioning hole and a positioning pin are provided between the side of the battery module and the bottom of the battery pack housing. The positioning hole is inserted into the positioning pin to position the battery module and the battery pack housing.

[0021] By using the positioning holes and positioning pins, the module is accurately positioned inside the housing, preventing the module from shifting or tilting during the adhesive pressing process. This ensures that the glue is evenly squeezed onto the bottom of the module, resulting in a uniform glue layer thickness distribution. It also prevents measurement data distortion caused by uneven local stress, further improving the representativeness and reliability of the measurement results.

[0022] In some embodiments of this application, in step S4. module removal, the auxiliary tool can be a hoisting tool, and the battery module is removed vertically along the opening direction of the battery pack housing.

[0023] The lifting tool allows the module to be lifted vertically along the opening of the housing, which can prevent the module from tilting or shaking during the removal process, prevent the release film from tearing and the adhesive layer from breaking, and ensure that the adhesive layer is intact. There is no need to repeat the glue application and pressing operation, which improves measurement efficiency. At the same time, it prevents the module from scratching the bottom plane of the housing, protecting the appearance and performance of the components.

[0024] In some embodiments of this application, after step S4. module removal, the isolation film and adhesive layer are checked for integrity. If the adhesive layer is damaged, step S1. stick adhesive application, step S2. isolation film covering, step S3. module placement and pressing, step S4. module removal are repeated until the isolation film and adhesive layer are intact.

[0025] After removing the module, check the integrity of the release film and adhesive layer. If the adhesive layer is damaged, repeat the operation. This can eliminate the problem of thickness measurement failure or inaccurate measurement data caused by adhesive layer damage, ensuring that valid data can be obtained for each measurement, avoiding the waste of glue, manpower and time due to invalid measurements, and further ensuring the reliability of measurement results.

[0026] In some embodiments of this application, during step S5, measuring the adhesive layer thickness, points are taken at equal intervals along the length of the adhesive layer and at equal intervals along the width of the adhesive layer, with at least two points taken along the width of the adhesive layer.

[0027] Taking points at equal intervals along the length and width of the adhesive layer, with at least two points in the width direction, can fully cover the entire adhesive layer area, avoiding the bias caused by single-point or small-scale measurements. This can accurately reflect the thickness distribution of the entire adhesive coating area, making it easier to identify problems such as excessively thick or thin adhesive coatings in certain areas, and providing more reliable data support for subsequent adhesive coating process optimization.

[0028] In some embodiments of this application, during step S5, when measuring the adhesive layer thickness, at least two measurements are performed at each point. When the difference in the measurement data of each point is less than 0.2 mm, the average value is taken as the measurement value of that point. When the difference in the data is greater than 0.2 mm, a third measurement is performed, and the average value of the three measurements is taken.

[0029] Each measurement point should be measured at least twice. The difference in data should be used to determine whether a third measurement is needed and the average value should be taken. This can effectively offset the random errors of a single measurement (such as caliper operation deviation or slight local deformation of the adhesive layer). The data difference should be limited to less than 0.2 mm to ensure the stability of the measurement data, avoid abnormal data from affecting the final result, and make the measurement data more accurate and reliable.

[0030] In some embodiments of this application, during step S5, the adhesive layer thickness measurement process, the calipers are held perpendicular to the adhesive layer surface and lightly clamped to avoid excessive force causing deformation of the adhesive layer.

[0031] The calipers should be held perpendicular to the adhesive layer surface and lightly clamped to prevent deformation of the adhesive layer due to caliper tilting or excessive force, thus avoiding overestimation or distortion of the measurement data, further improving measurement accuracy, and ensuring that the measured adhesive layer thickness can truly reflect the actual gap between the module and the housing.

[0032] In some embodiments of this application, after applying the adhesive in step S7, the adhesive is kept under pressure for 24 hours to allow it to fully cure. After curing, the bonding effect is checked to ensure that there is no looseness or gap between the module and the housing.

[0033] The curing time is limited to 24 hours to ensure that the adhesive is fully cured and to guarantee the bonding strength between the module and the casing. After curing, the bonding effect is checked to detect problems such as loose bonding and gaps in time, so as to prevent unqualified products from entering the subsequent process, improve the structural stability and sealing of the battery pack, and extend the service life of the battery pack. Attached Figure Description

[0034] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0035] Figure 1 This is a flowchart illustrating the battery pack coating thickness measurement method provided in an embodiment of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0037] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0038] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, when describing pipelines, the terms "connected" and "linked" as used in this application have the meaning of establishing electrical connection. The specific meaning needs to be understood in conjunction with the context.

[0040] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0041] Against the backdrop of the rapid development of the new energy vehicle industry, the battery pack, as a core power component of new energy vehicles, directly determines the driving safety and service life of the vehicle due to its structural stability, sealing, and safety. The battery pack mainly consists of two parts: modules and a housing. The modules, as the core of the battery pack's energy storage, need to be fixedly connected to the housing by applying adhesive, while ensuring the airtightness between the two to prevent external dust, moisture, and other impurities from entering the battery pack and causing corrosion, short circuits, or other damage to the battery modules, thereby affecting the performance and safety of the battery pack.

[0042] Adhesive coating thickness is a key process parameter in the connection between the battery pack module and the casing. Whether the adhesive coating thickness is reasonable and uniform directly affects the bonding strength, sealing performance, and overall structural stability of the battery pack. If the adhesive coating thickness is too thin, it will lead to insufficient bonding strength, making it easy for the module and casing to loosen or detach. At the same time, the sealing performance cannot be guaranteed, and external impurities can easily enter. If the adhesive coating thickness is too thick, it will not only waste adhesive and increase production costs, but also cause problems such as incomplete adhesive spreading and insufficient adhesive application area. This will result in uneven gaps between the module and casing, affecting the assembly accuracy of the battery pack. In fact, excessive stress generated during adhesive curing may even cause deformation of the casing or module, further affecting the performance of the battery pack.

[0043] Currently, existing methods for measuring adhesive thickness in battery pack enclosure coating applications have many defects and shortcomings, as detailed below:

[0044] First, the measurement accuracy is poor, with significant errors. Current technologies mostly use coordinate measuring machines (CMMs) to measure the gap between the module and the housing, indirectly estimating the adhesive thickness. However, the CMM measurement process requires fitting the flatness of the housing and module, which is prone to large errors, leading to significant deviations between the measured results and the actual adhesive thickness. Furthermore, during the adhesive application process, the housing itself has a certain elasticity and will deform under the pressure of the module. This deformation generates measurement noise, further interfering with the accuracy of the measurement results, making the data unreliable and unable to accurately reflect the actual gap and adhesive thickness between the module and the housing.

[0045] Secondly, the measurement methods are not intuitive and are cumbersome to operate. Most existing measurement methods are indirect and cannot directly obtain the true data of the adhesive coating thickness. They require complex calculations and conversions to obtain relevant information about the adhesive coating thickness. The operation process is cumbersome, requires high professional skills from operators, and has low measurement efficiency, which cannot meet the needs of rapid testing in large-scale production processes.

[0046] Third, the process validation cycle is long and costly. During the initial validation of the adhesive application process, the inability to quickly and accurately obtain adhesive thickness data necessitates repeated processes of adhesive application, assembly, measurement, and adjustment. This results in excessively long validation times, impacting production schedules and consuming significant amounts of adhesive, manpower, and material resources, thus increasing production costs. In actual production, the actual adhesive thickness often exceeds the theoretical thickness by more than twice. In such cases, the adhesive cannot be fully spread, and the bonding area is insufficient to meet adhesion and sealing requirements, necessitating a repeat adhesive application process, further exacerbating cost waste and inefficiency.

[0047] Fourth, it cannot achieve accurate multi-point measurement, resulting in insufficient data representativeness. Most existing measurement methods can only perform single-point or a small number of point measurements, and cannot comprehensively and multi-point measure the thickness of the adhesive coating on the entire contact surface between the module and the housing. As a result, the measurement data cannot reflect the thickness distribution of the entire adhesive coating area, making it difficult to detect problems such as excessively thick, thin, or uneven adhesive coating in certain areas, which in turn affects the overall quality of the battery pack.

[0048] Fifth, existing measurement tools and methods have poor adaptability. Different models and specifications of battery pack modules and housings have significant differences in size and structure. Existing measurement tools and methods are often unable to flexibly adapt to products of different specifications, requiring customized measurement tools and solutions for different products, which further increases production costs and operational complexity.

[0049] To address the problems existing in the prior art, this application provides a method for measuring adhesive coating thickness that effectively solves the above-mentioned defects, achieves accurate, rapid, and intuitive measurement of adhesive coating thickness, shortens the process verification cycle, reduces production costs, and is adaptable to battery packs of different specifications. This method can accurately, quickly, and intuitively measure the adhesive coating thickness between the module and the housing, eliminate measurement errors caused by housing concave deformation and three-coordinate plane fitting, reduce the number of process verifications and the amount of adhesive used, lower production costs, and is adaptable to battery packs of different specifications, improving measurement efficiency and data representativeness, and providing reliable technical support for the optimization and quality control of battery pack adhesive coating processes.

[0050] A method for measuring the adhesive thickness of a battery pack, please refer to... Figure 1 This includes steps S1 to S7.

[0051] S1. Applying stick-shaped glue: On the bottom plane of the battery pack box, along the length of the battery module, apply a continuous stick-shaped glue line manually or using a glue application device.

[0052] S2. Separator Covering: A separator is placed over the surface of the stick-shaped adhesive to ensure that the separator completely adheres to the surface of the stick-shaped adhesive, thus preventing the adhesive from directly contacting and sticking to the battery module.

[0053] S3. Module placement and adhesive pressing: Using an auxiliary positioning tool, accurately place the battery module into the battery pack box, ensuring that the bottom of the battery module is in close contact with the separator. Apply even pressure to the stick-shaped adhesive and flatten it.

[0054] S4. Module Removal: After maintaining the battery module under the pressure of the adhesive for a certain period of time, remove the battery module from the battery pack box using an auxiliary tool. At this time, the stick-shaped adhesive has been pressed into a uniform adhesive layer, and the adhesive layer is bonded to the separator.

[0055] S5. Adhesive layer thickness measurement: Remove the adhesive layer from the release liner, use calipers to measure the adhesive layer at multiple points, and record the adhesive layer thickness data at each measurement point.

[0056] S6. Data processing and analysis: The adhesive layer thickness data of all measurement points are processed and analyzed. The maximum value among all measurement data is taken as the actual gap value between the battery module and the battery pack housing. This gap value is the target adhesive thickness for subsequent wide-width adhesive application.

[0057] S7. Wide-width full-area adhesive coating: Based on the target adhesive coating thickness obtained in S6, wide-width full-area adhesive coating is applied to the bottom plane of the battery pack housing. The adhesive coating thickness is controlled within the range of ±0.1mm of the target adhesive coating thickness to complete the battery pack adhesive coating process.

[0058] Before step 1 (S1), there may be preparatory steps, such as preparatory work, which may include the preparation and inspection of the battery pack housing, battery modules, measuring adhesive, separator, calipers, and auxiliary positioning tools.

[0059] Specifically, the battery pack housing is the mounting carrier for the battery modules, used to support and protect them, and is fixedly connected and sealed to the battery modules through adhesive application. It is one of the core load-bearing structures of this measurement method.

[0060] For example, the battery pack housing is mainly made of high-strength aluminum alloy, stainless steel or engineering plastic, with high-strength aluminum alloy being the most widely used.

[0061] Specifically, 6061 aluminum alloy and 6063 aluminum alloy can be selected. These aluminum alloys have advantages such as low density, high strength, corrosion resistance and good processing performance, which can meet the requirements of lightweight battery pack and structural strength. At the same time, they have good thermal conductivity, which can help the battery module dissipate heat.

[0062] For battery packs in new energy passenger vehicles where weight is a critical factor, high-strength engineering plastics such as PC / ABS alloys and PA66 reinforced plastics can be used. These materials have advantages such as light weight, low cost, and good formability. For battery packs in commercial vehicles where structural strength is extremely critical, stainless steel materials such as 304 stainless steel and 316 stainless steel can be used, which have extremely high strength and corrosion resistance.

[0063] For example, the shape of the battery pack housing is designed mainly based on the size of the battery module, the installation space, and the overall vehicle layout. The common shape is a cuboid, while some special models can be designed as cubes, irregular cuboids, etc.

[0064] The box has an open structure with an opening at the top for holding the battery module and a flat bottom. This flat surface is the core area for adhesive application and measurement. The bottom surface is required to have a high degree of flatness, with a flatness error of no more than 1.0mm for every 300mm × 300mm of height difference, to ensure uniform adhesive application and accurate measurement.

[0065] The four sides of the enclosure are perpendicular to the bottom plane, and the height of the sides matches the height of the battery module, ensuring that the battery module can be positioned and limited by the sides of the enclosure after it is placed inside. The bottom of the enclosure is usually equipped with reinforcing ribs, which are strip-shaped, grid-shaped, or honeycomb-shaped, to improve the structural strength of the bottom of the enclosure and prevent excessive concave deformation during the pressing process, which would affect the measurement results.

[0066] For example, the dimensions of the battery pack housing are determined according to the specifications of the battery module and the requirements of the vehicle. There is no fixed standard. Common size ranges are as follows: length is 800mm-2000mm, width is 500mm-1500mm, height is 80mm-200mm, and the thickness of the bottom plane is 5mm-15mm.

[0067] For example, the battery pack housing for compact new energy passenger vehicles has a length of 1200mm, a width of 800mm, a height of 120mm, and a bottom plane thickness of 8mm; the battery pack housing for medium-sized new energy commercial vehicles has a length of 1800mm, a width of 1200mm, a height of 180mm, and a bottom plane thickness of 12mm.

[0068] The dimensions of the adhesive application area on the bottom plane of the casing match the dimensions of the bottom of the battery module. Typically, the length of the adhesive application area is 20mm-50mm longer than the length of the battery module, and the width is 20mm-50mm wider than the width of the battery module, to ensure full adhesion and sealing between the module and the casing.

[0069] For example, during use, the bottom plane of the battery pack housing is placed horizontally, serving as a reference surface for adhesive application and measurement. The battery module is placed within the adhesive application area on the bottom plane of the housing, parallel to and in close contact with the bottom plane (achieved through adhesive application). The sides of the housing correspond to the sides of the battery module, serving to position and limit movement, preventing the battery module from shifting within the housing.

[0070] The core function of the battery pack housing is to support the battery modules, provide installation space and protection for the battery modules, and achieve a fixed connection and seal with the battery modules through the application of adhesive to the bottom plane, ensuring the structural stability and sealing of the battery pack.

[0071] In the measurement method of this invention, the bottom plane of the box serves as the carrier for adhesive application and is the area for applying the roller-shaped adhesive. Its flatness and structural strength directly affect the uniformity of adhesive application and the thickness of the adhesive layer after pressing, thus affecting the accuracy of the measurement results. The reinforcing ribs of the box can effectively suppress concave deformation during the pressing process, reduce measurement noise, and improve measurement accuracy.

[0072] In some examples, the battery module is the energy storage core of the battery pack, which is composed of multiple individual batteries connected in series and parallel. It is the core structure used to squeeze the glue in this measurement method. Its bottom is in contact with the glue, and it flattens the stick-shaped glue by its own weight and external pressure, thereby reflecting the actual gap between the module and the box.

[0073] For example, the outer casing of the battery module is mainly made of aluminum alloy, stainless steel or engineering plastic, which matches the material of the battery pack housing to ensure compatibility and bonding effect between the two.

[0074] The module housing is usually made of 6061 aluminum alloy sheet, which is formed by stamping, bending and other processes. It has the advantages of light weight, high strength and good thermal conductivity, which can protect the internal individual cells and help dissipate heat from the individual cells.

[0075] The individual cells inside the module primarily use lithium-ion batteries, such as ternary lithium batteries and lithium iron phosphate batteries. The outer casing of each individual cell is made of aluminum or steel, providing good sealing and safety. The module also contains components such as tabs and connecting plates. The tabs are made of copper or aluminum, and the connecting plates are made of copper or aluminum sheets, used to achieve electrical connections between the individual cells.

[0076] Illustratively, the battery module may be in the shape of a cuboid, which matches the internal shape of the battery pack case to ensure that it can be smoothly placed into the case and achieve accurate positioning.

[0077] The bottom of the module is a planar structure, which is parallel to the bottom plane of the battery pack case. The bottom plane is required to have high flatness: the flatness error of the module is not more than 0.15mm / m, and the height difference within any 300mm×300mm area of the case is 1.0mm, so as to ensure that the glue can be uniformly extruded during the glue pressing process, resulting in a uniform adhesive layer thickness. The top of the module is usually provided with components such as terminals and sampling lines, which are used to realize electrical connection and signal transmission between the module and the battery management system (BMS).

[0078] Positioning grooves or positioning holes are provided on the side surface of the module, which cooperate with positioning protrusions or positioning pins on the side surface of the battery pack case to realize accurate positioning of the module in the case and prevent the module from shifting during the glue pressing process.

[0079] Illustratively, the dimensions of the battery module are determined according to the dimensions of the battery pack case and the energy requirement of the whole vehicle. Common dimension ranges are as follows: the length is 700mm-1900mm, the width is 400mm-1400mm, the height is 70mm-190mm, and the thickness of the bottom plane is 3mm-10mm.

[0080] For example, for a battery module matched with a battery pack case of a compact new energy passenger vehicle, the length is 1150mm, the width is 750mm, the height is 110mm, and the thickness of the bottom plane is 5mm; for a battery module matched with a battery pack case of a medium-sized new energy commercial vehicle, the length is 1750mm, the width is 1150mm, the height is 170mm, and the thickness of the bottom plane is 8mm. The dimension of the bottom plane of the module matches the dimension of the glue coating area on the bottom of the case, ensuring that the module can completely cover the glue coating area after being placed, and comprehensively and uniformly extrude the glue.

[0081] Illustratively, the battery module and the battery pack case are fixedly connected by gluing. The glue is uniformly applied to the glue coating area on the bottom plane of the case. After the module is placed, the glue fills the gap between the module and the case under the pressure of the module. After the glue is cured, firm bonding between the module and the case is realized.

[0082] In the measurement process of the present invention, the module and the case are separated by an isolation film, which covers the strip-shaped glue to avoid direct adhesion between the module and the glue, facilitating taking out the module and the adhesive layer after the measurement is completed. The module and the case are also detachably connected through a positioning structure (positioning groove and positioning protrusion, positioning hole and positioning pin), which ensures accurate positioning when placing the module and facilitates taking out the module after the measurement is completed.

[0083] For example, after the battery module is placed into the battery pack housing, its bottom plane is parallel to the bottom plane of the housing, and the two are separated by a separator and a stick-shaped adhesive, with the distance equal to the initial height of the stick-shaped adhesive; after the adhesive is pressed, the bottom plane of the module is in close contact with the separator, and the adhesive is pressed into a uniform adhesive layer. At this time, the distance between the module and the housing is equal to the thickness of the adhesive layer.

[0084] The side of the module and the side of the box are matched by a positioning structure, and the center of the module coincides with the center of the box, ensuring that the module is accurately positioned in the box and avoiding uneven force during the pressing process.

[0085] The core function of a battery module is to store electrical energy and provide power for new energy vehicles. In the measurement method of this invention, the core function of the module is to compress the stick-shaped adhesive by its own weight and external pressure, flattening the adhesive layer so that its thickness is equal to the actual gap between the module and the housing. Thus, the gap value between the module and the housing is obtained by measuring the thickness of the adhesive layer.

[0086] The flatness of the bottom plane of the module directly affects the uniformity of adhesive application. If the bottom plane of the module is uneven, it will lead to uneven force on the adhesive and uneven distribution of the adhesive layer thickness, affecting the accuracy of the measurement results. The positioning structure of the module can ensure that the module does not shift during the adhesive application process, ensuring the uniformity of adhesive extrusion and the reliability of the measurement data.

[0087] In some examples, the measuring adhesive is the core medium of this measurement method, used to simulate the adhesive in the subsequent coating process. Its thickness after being squeezed reflects the actual gap between the module and the housing, and its performance directly determines the accuracy and reliability of the measurement results.

[0088] For example, the material of the adhesive used for measurement is the same as the coating material used in the actual production process of the battery pack, mainly polyurethane (PU) adhesive, silicone adhesive or epoxy adhesive, among which polyurethane adhesive is the most widely used.

[0089] Polyurethane adhesive has advantages such as good fluidity, high bonding strength, moderate curing speed, and small compression deformation. It can deform uniformly under pressure, accurately reflecting the gap between the module and the box. At the same time, it has good compatibility with the release liner, does not easily stick to the release liner, and is easy to remove the adhesive layer after measurement.

[0090] Silicone adhesives have good high temperature resistance and aging resistance, making them suitable for battery packs with high temperature resistance requirements; epoxy adhesives have advantages such as extremely high bonding strength and high hardness, making them suitable for battery packs with high bonding strength requirements.

[0091] The viscosity range of the adhesive used for measurement is 10000mPa·s-50000mPa·s. The viscosity is moderate, which can ensure that it forms a continuous rod-like structure when applied and can deform evenly under pressure, without excessive flow or failure to deform.

[0092] For example, the measuring adhesive is applied in the form of a stick, specifically a cylindrical or cuboid shape. Its cross-sectional shape can be adjusted according to the measurement requirements. A cylindrical shape is preferred because cylindrical adhesive is subjected to uniform force when squeezed, which can form an adhesive layer of uniform thickness.

[0093] The length of the stick-shaped adhesive matches the length of the battery module, typically 10mm-30mm longer, to ensure it covers the entire length of the bottom of the module. The initial diameter (or side length of the cross section) of the stick-shaped adhesive is 3mm-8mm, and the initial height (i.e., initial thickness) is greater than the maximum theoretical gap between the module and the housing, ensuring that the adhesive can be fully squeezed during the pressing process, preventing insufficient adhesive from reflecting the actual gap.

[0094] For example, for a battery pack with a maximum theoretical gap of 2mm between the module and the housing, the initial diameter of the stick adhesive can be 5mm to ensure that an adhesive layer with a thickness of not less than 2mm can be formed after pressing, so as to accurately reflect the actual gap.

[0095] For example, the specific dimensions of the stick-shaped adhesive are determined based on the dimensions of the battery module and the theoretical gap between the module and the housing. Common size ranges are as follows: length 710mm-1930mm, initial diameter 3mm-8mm, and initial volume 5cm³-50cm³.

[0096] For example, the stick-shaped adhesive for a battery module with a length of 1150mm has a length of 1170mm, an initial diameter of 5mm, and an initial volume of 22.6cm³; the stick-shaped adhesive for a battery module with a length of 1750mm has a length of 1770mm, an initial diameter of 6mm, and an initial volume of 48.6cm³.

[0097] The dimensional error of the stick-shaped adhesive is controlled within ±0.5mm to ensure that the size of the adhesive after application is uniform and to avoid uneven adhesive layer thickness after pressing due to dimensional deviation, which would affect the measurement results.

[0098] For example, when the measuring adhesive is applied, it adheres directly to the bottom plane of the battery pack housing, forming a tight connection with the bottom plane of the housing. There are no additional connecting parts, and the fixation is achieved by the adhesive itself, preventing displacement when placing the separator and module.

[0099] The adhesive and the release liner are detachable. The release liner covers the surface of the adhesive and adheres to it by the adhesive properties, but it will not stick together, making it easy to remove the adhesive layer from the release liner after measurement.

[0100] The adhesive does not come into direct contact with the battery module; instead, it is separated by a separator to prevent the adhesive from sticking to the bottom of the module. This ensures that the module can be easily removed and also prevents the bottom of the module from being contaminated by the adhesive.

[0101] For example, the stick-shaped adhesive is applied along the length of the battery module to the center of the bottom plane of the battery pack box, perpendicular to the bottom plane of the box, and its axis is parallel to the length of the module, so as to ensure that the adhesive can be squeezed evenly after the module is placed in.

[0102] The adhesive covers the entire length of the bottom of the module along its length, and is located in the central area of ​​the bottom of the module along its width (cross-sectional direction). This ensures that the adhesive, when squeezed, forms a layer that covers the central area of ​​the bottom of the module, providing a sufficient measurement area for multi-point measurements.

[0103] It can be explained that the core function of the measuring adhesive is to serve as a measuring medium, reflecting the actual gap between the module and the housing through its thickness after being squeezed.

[0104] During the measurement process, the stick-shaped glue is subjected to pressure from the module, causing it to undergo elastic deformation and be pressed into a uniform glue layer. The thickness of the glue layer is equal to the actual gap between the module and the box. Therefore, by measuring the thickness of the glue layer, the gap value between the module and the box can be obtained, and this gap value is the target thickness for subsequent wide-width glue application.

[0105] The fluidity and compression set properties of the adhesive directly affect the accuracy of the measurement results. If the adhesive is too fluid, it will result in uneven adhesive layer thickness after pressing. If the adhesive has poor compression set properties, it will not be able to accurately reflect the actual gap. Therefore, it is necessary to strictly control the performance parameters of the adhesive.

[0106] In some examples, the separator is an auxiliary structure in the measurement method of the present invention, used to isolate the measuring adhesive from the battery module, prevent the adhesive from sticking to the bottom of the module, and ensure that the adhesive can be completely retained after being squeezed, so as to facilitate subsequent thickness measurement. Its performance and size directly affect the convenience and accuracy of the measurement.

[0107] For example, the material of the release liner is mainly polyethylene (PE), polypropylene (PP) or polytetrafluoroethylene (PTFE) film. These materials have good anti-stick properties, flexibility and corrosion resistance, which can effectively prevent the glue from sticking to the bottom of the module. At the same time, they have good ductility and can deform with the glue during the pressing process without being torn, and will not react chemically with the glue, ensuring that the performance of the glue is not affected.

[0108] Among them, polytetrafluoroethylene (PTFE) film has the best anti-stick properties and is suitable for strong adhesives; polyethylene (PE) film has the best flexibility and is relatively inexpensive, making it suitable for most common adhesives; polypropylene (PP) film has good temperature resistance and is suitable for measurement scenarios with specific temperature requirements. The thickness of the release liner should be 0.01mm-0.05mm. If the liner is too thin, it is easily torn; if it is too thick, it will increase measurement errors and affect the accuracy of the measurement results.

[0109] For example, the separator is rectangular in shape, larger than the size of the stick adhesive to ensure complete coverage of the stick adhesive surface, while being slightly smaller than the bottom of the battery module to prevent the separator from extending beyond the bottom of the module and affecting the module's positioning and bonding effect.

[0110] The four corners of the isolation membrane can be rounded to avoid sharp edges scratching the bottom of the module or the bottom surface of the box.

[0111] For example, the size of the separator is determined based on the size of the stick adhesive and the battery module. Common size ranges are as follows: length 720mm-1940mm, width 50mm-100mm, and thickness 0.01mm-0.05mm.

[0112] For example, the release film used with a stick of glue with a length of 1170 mm and an initial diameter of 5 mm has a length of 1180 mm, a width of 80 mm, and a thickness of 0.03 mm; the release film used with a stick of glue with a length of 1770 mm and an initial diameter of 6 mm has a length of 1780 mm, a width of 90 mm, and a thickness of 0.03 mm.

[0113] The size error of the release liner is controlled within ±1mm to ensure complete coverage of the adhesive surface without affecting the positioning of the module.

[0114] For example, the release liner and the measuring adhesive are bonded together, relying on the adhesive's own stickiness to cover the adhesive surface. There are no additional connecting parts, the connection method is simple, and it can be easily separated, making it convenient to remove the adhesive layer after the measurement is completed.

[0115] The separator is connected to the bottom of the battery module by contact, without adhesive. After the module is placed in, the separator is in close contact with the bottom of the module and deforms together with the adhesive under the pressure of the module, without displacement or falling off.

[0116] There is no direct connection between the separator and the bottom plane of the battery pack housing; positioning is achieved solely through adhesive support to ensure that it does not shift during the pressing process.

[0117] For example, the release film covers the entire surface of the stick-shaped adhesive, is completely adhered to the adhesive surface, is parallel to the length direction of the adhesive, and covers the entire cross-section of the adhesive in the width direction, ensuring that the adhesive does not come into direct contact with the module.

[0118] The center of the release liner should coincide with the center of the adhesive, and its edge should extend 5mm-10mm beyond the edge of the adhesive to ensure complete coverage of the adhesive and prevent the adhesive from being exposed and sticking to the module.

[0119] The release liner is located between the bottom of the module and the adhesive, forming an isolation layer that prevents the bottom of the module from directly contacting the adhesive while not affecting the module's ability to compress the adhesive.

[0120] Specifically, the core function of the release liner is to isolate the adhesive from the module, preventing the adhesive from sticking to the bottom of the module and ensuring that the module can be easily removed, while protecting the bottom of the module from adhesive contamination. In addition, the release liner ensures that the adhesive forms a complete layer after being squeezed, preventing adhesive from sticking to the bottom of the module and causing the adhesive layer to break, thus making thickness measurement impossible.

[0121] The flexibility and extensibility of the release liner ensure that it deforms along with the adhesive during the lamination process without affecting the thickness of the adhesive layer, thus ensuring the accuracy of the measurement results.

[0122] The non-stick properties of the release liner allow the adhesive layer to be easily removed from the release liner after measurement, facilitating thickness measurement using calipers.

[0123] In some examples, calipers are the core measuring tool in the measurement method of this invention, used to measure the thickness of the adhesive layer after pressing. Their accuracy directly determines the accuracy of the measurement results, and calipers with appropriate accuracy and specifications need to be selected according to the measurement requirements.

[0124] For example, the main body material of calipers is high carbon steel, stainless steel or hard alloy, among which stainless steel is the most widely used, such as 304 stainless steel and 316 stainless steel. These materials have the advantages of high hardness, good wear resistance, corrosion resistance and not easy deformation, which can ensure the measurement accuracy and service life of calipers.

[0125] The measuring jaws of calipers are usually made of cemented carbide, which has higher hardness and better wear resistance, thus improving the accuracy and stability of measurements.

[0126] The dial or display screen of a caliper is made of glass or plastic. Glass dials have the advantages of high clarity and resistance to wear, while plastic displays have the advantages of light weight and low cost.

[0127] For example, the caliper is elongated in shape and mainly consists of a main scale, a secondary scale (or display screen), measuring jaws, a depth gauge, and locking screws. The measuring jaws are divided into inner and outer measuring jaws. The outer measuring jaws are used to measure the thickness of the adhesive layer. They are flat in shape with a planar measuring surface to ensure close contact with the adhesive layer surface for accurate measurement.

[0128] The main scale is long and narrow with graduations for reading the integer part of the measurement; the secondary scale (or display screen) is located on the main scale and can slide along it for reading the decimal part of the measurement. The display screen of a digital caliper can directly display the measurement value, making it more convenient to operate and more accurate.

[0129] Locking screws are used to fix the position of the vernier scale (or display screen) to ensure that it does not slip during measurement and improve measurement stability.

[0130] For example, the specifications of the calipers are determined according to the thickness range of the adhesive layer. Common specifications are 0-150mm and 0-200mm, and their measurement range can completely cover the thickness of the adhesive layer in the measurement method of the present invention (usually 0.5mm-5mm).

[0131] Calipers come in two precision levels: 0.01mm and 0.02mm. It is preferable to use calipers with a precision of 0.01mm to ensure the accuracy of the measurement results and to accurately capture subtle changes in the thickness of the adhesive layer.

[0132] For example, a digital caliper with a range of 0-150mm and an accuracy of 0.01mm is selected. Its main scale has a scale interval of 1mm, and the secondary scale (display screen) can display up to 0.01mm. The measurement error is no greater than ±0.01mm, which can meet the measurement requirements of this invention.

[0133] For example, calipers are used to measure the thickness of the adhesive layer after pressing. When using them, gently clamp the outer measuring jaws of the calipers onto the adhesive layer, ensuring that the measuring jaws are perpendicular to and in close contact with the surface of the adhesive layer. Avoid applying too much force, which could deform the adhesive layer and affect the measurement results.

[0134] During measurement, read the values ​​on the main scale and the secondary scale (or the display screen), record the measurement data, and measure each point three times. Take the average value as the final thickness data for that point to reduce measurement error.

[0135] For example, during the measurement process, the calipers and the adhesive layer are in contact, and the measuring surfaces of the outer measuring jaws are in close contact with the upper and lower surfaces of the adhesive layer to ensure the accuracy of the measurement.

[0136] Place the adhesive layer on a flat workbench and measure it with calipers perpendicular to the surface of the adhesive layer to avoid tilting the measurement, which would result in an overestimation of the value.

[0137] It can be explained that the core function of calipers is to measure the thickness of the adhesive layer. By measuring the thickness of the adhesive layer at different points, the gap data between the module and the housing can be obtained.

[0138] The precision of calipers directly affects the accuracy of measurement results. High-precision calipers can accurately measure minute changes in the thickness of the adhesive layer, ensuring that the obtained gap value is true and reliable, and providing an accurate target thickness for subsequent wide-width adhesive coating.

[0139] During the measurement process, by taking measurements at multiple points and using the maximum value, local measurement errors can be effectively avoided, ensuring the representativeness of the measurement data and reflecting the maximum gap between the module and the housing, thereby avoiding bonding and sealing problems caused by insufficient adhesive thickness in the subsequent application.

[0140] In some examples, the auxiliary positioning tool is an auxiliary structure in this measurement method, used to achieve accurate positioning of the battery module in the battery pack box, prevent the module from shifting during the adhesive pressing process, ensure that the adhesive can be squeezed evenly, improve the accuracy of the measurement results, and facilitate the insertion and removal of the module.

[0141] For example, the auxiliary positioning tool is mainly made of aluminum alloy, stainless steel or engineering plastic, which matches the material of the battery pack housing and module to avoid scratches or corrosion to the housing and module.

[0142] Aluminum alloy is the most widely used material due to its advantages of light weight, high strength, and good machinability, and it can be customized according to the dimensions of the housing and module. For positioning tools with high precision requirements, stainless steel can be selected, which has higher strength and stability; for applications with high weight requirements, engineering plastics such as PA66 reinforced plastic can be selected.

[0143] For example, the shape of the auxiliary positioning tool is designed according to the structure of the battery pack housing and module. Common shapes include positioning blocks, positioning pins, positioning frames, etc., which can be used individually or in combination.

[0144] The positioning block is rectangular or cubic in shape with a flat surface. It is used to fit the sides of the box and the module to achieve lateral positioning of the module. The positioning pin is cylindrical in shape. One end is fixed to the bottom plane or side of the box, and the other end is inserted into the positioning hole of the module to achieve precise positioning of the module. The positioning frame is a frame structure that matches the shape of the module. It is used to fix the module in the positioning frame, and then the positioning frame is placed into the box to achieve overall positioning of the module.

[0145] The surface of the auxiliary positioning tool needs to be polished, with a surface roughness of no more than Ra1.6μm, to avoid scratching the housing and module.

[0146] For example, the size of the auxiliary positioning tool is determined based on the size of the battery pack housing and module, and there is no fixed standard; it must match the positioning structure of the housing and module.

[0147] For example, the positioning block has a length of 50mm-100mm, a width of 30mm-50mm, and a height of 80mm-200mm, matching the dimensions of the side of the box and the side of the module to ensure a tight fit; the positioning pin has a diameter of 5mm-10mm and a length of 20mm-50mm, matching the dimensions of the positioning holes on the module to ensure smooth insertion into the positioning holes without loosening; the positioning bracket matches the dimensions of the module, with a length 20mm-40mm longer than the module length, a width 20mm-40mm wider than the module width, and a height 10mm-20mm higher than the module height, ensuring the module is securely fixed.

[0148] For example, the auxiliary positioning tool is detachably connected to the battery pack housing. The positioning block is fixed to the side or bottom plane of the housing by bolts, the positioning pin is fixed to the housing by interference fit or threaded connection, and the positioning frame achieves positioning by engaging with the housing through the positioning groove.

[0149] The auxiliary positioning tool is connected to the battery module by contact. The positioning block fits against the side of the module, the positioning pin is inserted into the positioning hole of the module, and the positioning frame wraps around the module to achieve accurate positioning of the module without damaging it, making it easy to put the module in and take it out.

[0150] For example, the auxiliary positioning tool is installed on the side or bottom plane of the battery pack housing, and the positioning block is located between the side of the housing and the side of the module, fitting the sides of both; the positioning pin is fixed on the bottom plane or side of the housing, and its axis is perpendicular or parallel to the bottom plane of the housing, and is inserted into the positioning hole of the module; the positioning frame is placed inside the housing, the module is located inside the positioning frame, and the inner wall of the positioning frame fits against the side of the module.

[0151] The position of the auxiliary positioning tool corresponds to the positioning structure of the module, ensuring that the module can be accurately positioned after it is placed in, and that the center of the module coincides with the center of the box, thus preventing the module from shifting during the pressing process.

[0152] It can be explained that the core function of the auxiliary positioning tool is to achieve precise positioning of the module within the housing, preventing displacement or tilting of the module during the adhesive application process. This ensures that the bottom of the module is evenly compressed with the roller-shaped adhesive, resulting in a uniform adhesive layer thickness and improved measurement accuracy. Furthermore, the auxiliary positioning tool facilitates the insertion and removal of the module, reducing deviations during insertion and improving operational efficiency.

[0153] The positioning accuracy of the auxiliary positioning tool directly affects the measurement results. The higher the positioning accuracy, the more precise the position of the module, the more uniform the adhesive application, and the more reliable the measurement data.

[0154] It can be explained that this invention directly simulates the gap between the module and the housing using a stick-shaped adhesive. Utilizing the elastic deformation characteristics of the adhesive, the gap is converted into the thickness of the adhesive layer. By measuring at multiple points with calipers and taking the maximum value, the actual gap between the module and the housing can be accurately reflected, eliminating the errors caused by three-coordinate plane fitting in existing technologies. Simultaneously, by covering the adhesive with a release film and adding reinforcing ribs to the bottom of the housing, measurement noise caused by the concave deformation of the housing during the adhesive application process is effectively suppressed, further improving measurement accuracy. The measurement error can be controlled within ±0.01mm, far lower than the measurement error of existing technologies.

[0155] By directly measuring the adhesive layer thickness, no complex calculations or conversions are required. The gap between the module and the housing can be directly obtained, the operation process is simple, and the professional skills required of the operators are low, facilitating large-scale application. Furthermore, the measurement process is rapid, taking only 30-60 minutes from adhesive application to completion, far shorter than the process verification time of existing technologies, significantly improving measurement efficiency.

[0156] This method can quickly and accurately obtain adhesive thickness data without repeatedly performing adhesive application, assembly, measurement, and adjustment processes. It can shorten the initial process verification time by more than 80%, significantly improving production progress. Simultaneously, by accurately measuring and determining the target adhesive thickness, it can avoid glue waste caused by excessive application, reducing glue usage by 30%-50%, lowering production costs, and preventing rework due to substandard adhesive application, further reducing production and labor costs.

[0157] By performing multiple measurements on the adhesive layer, the thickness distribution of the entire adhesive application area can be comprehensively reflected, identifying problems such as excessively thick, thin, or uneven adhesive application in certain areas, providing reliable data support for optimizing the adhesive application process. Simultaneously, taking the maximum value of the measured data as the target adhesive thickness ensures that the thickness of subsequent wide-area adhesive application meets bonding and sealing requirements, avoiding sealing failures caused by excessively large local gaps.

[0158] The measurement method can be adjusted according to different models and specifications of battery pack boxes and modules. The size of the stick adhesive, the size of the separator, and the specifications of the auxiliary positioning tools can be adjusted. There is no need to customize special measurement tools and measurement schemes. It can flexibly adapt to the coating thickness measurement needs of various new energy vehicle battery packs and has strong versatility.

[0159] The release film separates the adhesive from the module, preventing the adhesive from sticking to the bottom of the module and contaminating the bottom of the module. It also prevents scratches on the bottom surface of the box when the module is removed, protecting the appearance and performance of the module and the box, and reducing product loss.

[0160] Specifically, in some embodiments, a method for measuring the coating thickness of a battery pack is applicable to the battery pack of a compact new energy passenger vehicle. The battery pack is used in passenger vehicles with a range of 400km-500km. The battery pack housing is rectangular, the battery modules are rectangular, and the theoretical gap between the modules and the housing is 1mm-2mm.

[0161] Battery pack casing preparation: A rectangular battery pack casing made of 6061 aluminum alloy is selected, with dimensions of 1200mm length, 800mm width, and 120mm height. The bottom plane thickness is 8mm, and the bottom plane is equipped with a grid-like reinforcing rib with a rib thickness of 5mm. The flatness error of the module is no greater than 0.15mm / m. The height difference within any 300mm×300mm area of ​​the casing is 1.0mm. The adhesive application area is 1180mm long and 780mm wide, located at the center of the bottom plane of the casing. Check that the bottom plane of the casing is flat, free of oil stains and debris. If oil stains or debris are present, wipe them clean with anhydrous ethanol to ensure that the adhesive can adhere tightly to the bottom plane of the casing.

[0162] Battery module preparation: A rectangular battery module with a 6061 aluminum alloy casing is selected, with dimensions of 1150mm in length, 750mm in width, and 110mm in height. The bottom plane thickness is 5mm, and the flatness error of the bottom plane is no greater than 0.03mm / m. Two 8mm diameter positioning holes are provided on the side of the module, located at both ends along its length. Check that the bottom plane of the module is flat, free of oil stains and scratches, to ensure that the adhesive can be evenly applied during the bonding process.

[0163] Preparation of adhesive for measurement: Polyurethane (PU) adhesive with a viscosity of 25000 mPa·s and a transparent color is selected. Its material is consistent with the coating material used in the actual production of this battery pack. The initial shape of the adhesive is a cylindrical rod with a length of 1170 mm, an initial diameter of 5 mm, and an initial volume of 22.6 cm³, with dimensional errors controlled within ±0.5 mm. The adhesive is preheated in an environment of 25℃±2℃ for 30 minutes to ensure that the adhesive's fluidity and viscosity are at their optimal state.

[0164] Release film preparation: Use polyethylene (PE) release film with a thickness of 0.03mm, rectangular shape, and dimensions of 1180mm in length and 80mm in width. The four corners should be rounded, and the dimensional error should be controlled within ±1mm. Check that the release film is intact, undamaged, and wrinkle-free, ensuring it completely covers the surface of the stick-shaped adhesive.

[0165] Caliper preparation: Select a digital caliper with a range of 0-150mm and an accuracy of 0.01mm. The measuring jaws should be made of carbide. Calibrate the caliper before measurement to ensure measurement accuracy. The calibration error should not exceed ±0.01mm.

[0166] Preparation of auxiliary positioning tools: Use aluminum alloy positioning blocks and pins. The positioning blocks are cuboid, 80mm long, 40mm wide, and 120mm high, totaling four blocks, used to fit the sides of the cabinet and modules respectively. The positioning pins are cylindrical, 8mm in diameter and 30mm long, totaling two pins, matched with the positioning holes on the side of the modules, and fixed to the bottom plane of the cabinet at both ends of the adhesive application area. Check that the surfaces of the auxiliary positioning tools are smooth and free of burrs to ensure they will not scratch the cabinet or modules.

[0167] S1. Applying Adhesive in a Rod: Using a manual application method, apply a continuous cylindrical strip of adhesive evenly from one end of the battery pack casing along the length of the battery module within the designated adhesive application area on the bottom surface of the casing. During application, maintain a uniform application speed (50mm / s-80mm / s) and stable application pressure (0.3MPa-0.5MPa) to ensure the adhesive rod has a uniform diameter, no breaks, no air bubbles, and adheres tightly to the bottom surface of the casing without peeling or shifting. After application, check the length and diameter of the adhesive rod to ensure it meets the preset size requirements. If any deviations are found, promptly apply additional adhesive or make adjustments.

[0168] S2. Covering with Release Film: Gently cover the surface of the stick-shaped adhesive with the prepared polyethylene release film. Press the release film gently with your hand to ensure it adheres completely to the adhesive surface, without air bubbles or wrinkles. Ensure the release film completely covers the adhesive, with the edges extending 8mm beyond the adhesive edge to prevent adhesive exposure. During the covering process, avoid applying excessive force that could deform the adhesive, ensuring that the initial shape and size of the adhesive are not affected.

[0169] S3. Module Placement and Adhesive Pressing: Using auxiliary positioning tools, accurately place the battery module into the battery pack housing. Align the positioning holes on the side of the module with the positioning pins on the bottom of the housing, and slowly insert the positioning pins. Simultaneously, ensure the positioning blocks align with the sides of the module and the housing to achieve precise module positioning, ensuring the center of the module coincides with the center of the housing and the bottom plane of the module is parallel to the separator membrane. After the module is placed, its own weight (approximately 50kg) compresses the adhesive, while applying uniform pressure (controlled at 0.1MPa-0.2MPa) to the top of the module. Maintain this compression for 30 minutes to evenly flatten the stick-shaped adhesive, forming a continuous and uniform adhesive layer. During the pressing process, observe whether the module shifts. If shifting occurs, adjust the module position promptly to ensure even adhesive pressing.

[0170] S4. Module Removal: After the adhesive is applied, slowly remove the pressure from the top of the module. Then, using an auxiliary tool (such as a lifting tool), gently lift the battery module upwards and remove it from the casing. During removal, keep the module vertical to prevent tilting, which could damage the separator and adhesive layer. Ensure the adhesive layer remains intact on the separator. After removal, check the separator and adhesive layer for damage. If the adhesive layer is damaged, the adhesive application and pressing process must be repeated.

[0171] S5 Adhesive Layer Thickness Measurement: Gently remove the adhesive layer from the release liner and place it on a flat workbench, ensuring the adhesive layer is flat, wrinkle-free, and undamaged. Using a calibrated digital caliper, perform multiple measurements on the adhesive layer. The measurement points are distributed as follows: along the length of the adhesive layer, one measurement point is set every 100mm, for a total of 12 measurement points (including both ends of the adhesive layer); at each measurement point, three measurement points are set along the width of the adhesive layer (left, center, and right). Each measurement point is measured three times, and the average value is taken as the thickness data for that measurement point. During the measurement process, the caliper is perpendicular to the surface of the adhesive layer, gently clamping the adhesive layer to avoid excessive force that could deform the adhesive layer and affect the measurement results.

[0172] S6 Data Processing and Analysis: The thickness data from the 36 measurement points were processed and analyzed, and the average, maximum, and minimum values ​​of all measurement data were calculated. The calculated average value was 1.30 mm, the minimum was 1.25 mm, and the maximum was 1.38 mm. According to the method of this invention, the maximum value of 1.38 mm was taken as the actual gap between the battery module and the battery pack housing, i.e., the target adhesive thickness for subsequent wide-width adhesive application.

[0173] Analysis of the measurement data shows that the adhesive layer thickness is uniformly distributed, with a difference of 0.13mm between the maximum and minimum values, indicating accurate module positioning, uniform adhesive application, and reliable measurement results. Furthermore, this actual gap value (1.38mm) is within the theoretical gap range (1mm-2mm), meeting design requirements and can be used as the target thickness for subsequent wide-width adhesive application.

[0174] S7. Wide-width full-area adhesive coating: Based on the target adhesive thickness (1.38mm) obtained in step S6, apply a wide-width full-area adhesive coating to the adhesive coating area on the bottom plane of the battery pack casing. Use automatic adhesive coating equipment, controlling the coating speed at 60mm / s-90mm / s, the coating pressure at 0.4MPa-0.6MPa, and the adhesive thickness within the range of 1.38mm±0.1mm, ensuring uniform coating without breaks, bubbles, or accumulation. After coating, check the adhesive thickness and uniformity; if deviations are found, promptly add adhesive or make adjustments.

[0175] The battery module is then placed back into the housing, and precise positioning is achieved using an auxiliary positioning tool. Uniform pressure (0.1MPa-0.2MPa) is applied and maintained under pressure for 24 hours to allow the adhesive to fully cure, achieving a firm bond and seal between the module and the housing. After curing, the bonding effect is checked; there is no looseness or gaps between the module and the housing, and the sealing performance is excellent, meeting the production requirements of the battery pack.

[0176] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0177] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring the thickness of adhesive coating on a battery pack, characterized in that, S1. Applying stick-shaped glue: On the bottom plane of the battery pack box, along the length of the battery module, apply a continuous stick-shaped glue line manually or using a glue application device. S2. Separator Covering: A separator is covered on the surface of the stick-shaped adhesive to ensure that the separator completely adheres to the surface of the stick-shaped adhesive, thus preventing the adhesive from directly contacting and sticking to the battery module; S3. Module placement and adhesive pressing: The battery module is precisely placed into the battery pack box using an auxiliary positioning tool, so that the bottom of the battery module is in close contact with the separator. The stick-shaped adhesive is evenly squeezed and flattened. S4. Module Removal: After maintaining the battery module under the pressure of the adhesive for a certain period of time, remove the battery module from the battery pack box using an auxiliary tool. At this time, the stick-shaped adhesive has been pressed into a uniform adhesive layer, and the adhesive layer is bonded to the separator. S5. Adhesive layer thickness measurement: Remove the adhesive layer from the release liner, use calipers to measure the adhesive layer at multiple points, and record the adhesive layer thickness data at each measurement point; S6. Data processing and analysis: The adhesive layer thickness data of all measurement points are processed and analyzed. The maximum value among all measurement data is taken as the actual gap value between the battery module and the battery pack box. This gap value is the target adhesive thickness for subsequent wide-width adhesive application. S7. Wide-width full-area adhesive coating: Based on the target adhesive coating thickness obtained in S6, wide-width full-area adhesive coating is applied to the bottom plane of the battery pack housing. The adhesive coating thickness is controlled within the range of ±0.1mm of the target adhesive coating thickness to complete the battery pack adhesive coating process.

2. The method for measuring the coating thickness of a battery pack according to claim 1, characterized in that, It also includes a preparation step, which precedes S1. The preparation step includes the preparation and inspection of the battery pack housing, battery modules, measuring adhesive, separator, calipers, and auxiliary positioning tools.

3. The method for measuring the coating thickness of a battery pack according to claim 1, characterized in that, In step S2, the separator film can be made of polyethylene, and the edge of the separator film extends at least 5 mm beyond the edge of the adhesive along the length of the battery module.

4. The method for measuring the coating thickness of a battery pack according to claim 1, characterized in that, In step S3, module insertion and sealing, a positioning hole and a positioning pin are provided between the side of the battery module and the bottom of the battery pack housing. The positioning hole is inserted into the positioning pin to position the battery module with the battery pack housing.

5. The method for measuring the coating thickness of a battery pack according to claim 1, characterized in that, In step S4, module removal, the auxiliary tool can be a hoisting tool, and the battery module is removed vertically along the opening direction of the battery pack housing.

6. The method for measuring the coating thickness of a battery pack according to claim 5, characterized in that, After step S4. Module Removal, check if the release liner and adhesive layer are intact. If the adhesive layer is damaged, repeat steps S1. Applying the stick adhesive, S2. Covering with the release liner, S3. Inserting the module into the box and pressing it with adhesive, and S4. Removing the module, until the release liner and adhesive layer are intact.

7. The method for measuring the coating thickness of a battery pack according to any one of claims 1 to 6, characterized in that, In step S5, when measuring the adhesive layer thickness, points are taken at equal intervals along the length of the adhesive layer and at equal intervals along the width of the adhesive layer, and at least two points are taken along the width of the adhesive layer.

8. The method for measuring the coating thickness of a battery pack according to claim 7, characterized in that, In step S5, when measuring the adhesive layer thickness, at least two measurements are performed at each point. If the difference between the measurement data at each point is less than 0.2 mm, the average value is taken as the measurement value at that point. If the difference between the data is greater than 0.2 mm, a third measurement is performed, and the average value of the three measurements is taken.

9. The method for measuring the coating thickness of a battery pack according to claim 8, characterized in that, In step S5, during the measurement of the adhesive layer thickness, the caliper is held perpendicular to the adhesive layer surface and lightly clamped to avoid excessive force that could deform the adhesive layer.

10. The method for measuring the coating thickness of a battery pack according to claim 1, characterized in that, After applying the adhesive in step S7, keep it under pressure for 24 hours to allow the adhesive to fully cure. After curing, check the bonding effect to ensure that there is no looseness or gap between the module and the box.

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