Battery pack, vehicle, and method of internal leakage protection and monitoring for battery pack

Abstract

The application relates to the technical field of vehicles, in particular to a battery pack, a vehicle and a battery pack internal liquid leakage protection and monitoring method. The battery pack comprises a shell, an electric core module arranged in the shell and a high-voltage circuit breaking unit; at least part of the gap between the shell and the electric core module and / or at least part of the surface of the high-voltage circuit breaking unit is provided with a waterproof layer, and the material of the waterproof layer comprises a foaming material. When liquid enters the battery pack, the waterproof layer can rapidly absorb water and expand, thereby filling the gap in the battery pack and wrapping the high-voltage component, realizing the isolation of the high-voltage component and the liquid, and avoiding the risk of insulation failure; at the same time, the waterproof layer can prevent the liquid from further penetrating into the battery pack, avoid the further deterioration of the insulation environment, slow down the occurrence of arc ignition, and give passengers time to escape. The method provided by the application realizes the automatic protection and monitoring of the battery pack internal liquid leakage condition, and improves the safety performance of the battery pack.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a battery pack, a vehicle, and a method for preventing and monitoring internal leakage of the battery pack. Background Technology

[0002] The safety of battery packs in new energy vehicles after a collision has always been a concern for the public. Currently, battery packs are generally located in the chassis of the vehicle. The liquid cooling plate inside the battery pack may rupture under stress or when the bottom of the vehicle is subjected to mechanical damage. The cooling medium inside the liquid cooling plate may enter the battery pack and come into contact with the high-voltage circuit, causing high-voltage insulation failure, which may lead to high-voltage arcing, battery pack fire and explosion, and cause a safety accident. Summary of the Invention

[0003] The first objective of this invention is to provide a battery pack containing a foaming material that can quickly absorb water and fill the internal space of the battery pack after water enters the battery pack, thereby separating the water from the high-voltage circuit and avoiding high-voltage arcing problems.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A battery pack includes a housing, and a cell module and a high-voltage circuit breaker unit disposed inside the housing; A waterproof layer is provided in at least a portion of the gap between the housing and the battery cell module and / or on at least a portion of the surface of the high-voltage circuit breaker unit, wherein the waterproof layer is made of foam material.

[0005] In some embodiments, the housing includes an upper cover assembly and a lower housing assembly that are interlocked, and the waterproof layer is provided on the upper cover assembly and / or the lower housing assembly.

[0006] In some embodiments, at least a portion of the interior area of ​​the top cover assembly is provided with the waterproof layer; And / or, the lower housing assembly includes a lower housing body, a liquid cooling plate disposed within the lower housing body, and a first structural adhesive layer disposed on the liquid cooling plate, the first structural adhesive layer being sandwiched between the liquid cooling plate and the battery cell module, and the lower housing assembly having at least a partial waterproof layer disposed in the remaining internal area avoiding the first structural adhesive layer.

[0007] In some embodiments, at least a portion of the outer surface of the battery cell module is provided with the waterproof layer, and at least a portion of the outer surface of the high-voltage circuit breaker unit is provided with the waterproof layer.

[0008] In some embodiments, the waterproof layer is at least partially a solid component with a specific shape; And / or, the waterproof layer is at least partially formed by spraying.

[0009] In some embodiments, the foaming material includes silicone foaming material and / or polyurethane foam; And / or, the expansion rate of the foamed material is greater than or equal to 10.

[0010] In some embodiments, the waterproof layer is doped with functional fillers, which include one or more of thermally conductive fillers, flame-retardant fillers, and color-changing fillers.

[0011] In some embodiments, the thermally conductive filler includes at least one of ceramic powder, alumina powder, thermally conductive silicone grease, thermally conductive gel, and thermally conductive potting compound; And / or, the flame-retardant filler includes at least one of ceramicized composite powder, aluminum hydroxide, and magnesium hydroxide; And / or, the proportion of the functional filler is not greater than 50% of the proportion of the foaming material.

[0012] In some embodiments, the system further includes a pressure sensing element array disposed on the surface of the waterproof layer, the pressure sensing element array being composed of a plurality of pressure sensing elements arranged at intervals; The pressure sensing element array and the high-voltage circuit breaker unit are both electrically connected to the control unit of the battery pack.

[0013] In some embodiments, a piezoelectric thin-film sensor disposed on the surface of the waterproof layer is further included. The piezoelectric thin-film sensor includes two sealed insulating encapsulation layers and the pressure sensing element array disposed between the two insulating encapsulation layers.

[0014] A second object of the present invention is to provide a vehicle comprising the battery pack described in any of the preceding claims.

[0015] A third objective of this invention is to provide a method for preventing and monitoring internal leakage of a battery pack, applied to the aforementioned battery pack, wherein the method includes: S1. Obtain the pressure detection signal output by each of the pressure detection elements; S2. Process the pressure values ​​corresponding to each pressure detection signal, and determine whether there is leakage inside the battery pack based on the data processing results.

[0016] In some embodiments, step S2 includes: Compare the pressure value corresponding to each pressure detection signal with the first preset pressure threshold. If the pressure value below the preset number is greater than the first preset pressure threshold, it is determined whether there is a false triggering situation; If it is determined that there is no accidental touch or the pressure value of no less than a preset number is greater than the first preset pressure threshold, it is determined that there is leakage inside the battery pack.

[0017] In some embodiments, determining whether a false touch has occurred includes: The duration of the pressure detection signal corresponding to a pressure value greater than a first preset pressure threshold is compared to whether it is greater than a preset duration; and / or, the rate of change of the pressure value is compared to whether it is greater than a preset rate of change; and / or, the pressure value corresponding to an adjacent pressure detection unit is compared to whether it is greater than a second preset pressure threshold, wherein the second preset pressure threshold is less than the first preset pressure threshold. The comparison results will determine whether there is any accidental touch.

[0018] In some embodiments, it also includes: S3. When it is determined that there is leakage inside the battery pack, output a first-level warning signal to the user, and / or predict the location of the leakage inside the battery pack and output it to the vehicle display screen for display. S4. When at least one pressure value is greater than a third preset pressure threshold, and the third preset pressure threshold is greater than the first preset pressure threshold, a secondary warning signal is output to the user and the high-voltage circuit of the battery pack is cut off.

[0019] The beneficial effects of this invention are: The present invention provides a battery pack and a vehicle equipped with the battery pack. The battery includes a housing and a cell module and a high-voltage circuit breaker unit disposed inside the housing. A waterproof layer is provided in at least a portion of the gap between the housing and the cell module and / or at least a portion of the surface of the high-voltage circuit breaker unit. The waterproof layer is made of a foam material.

[0020] This application incorporates a waterproof layer primarily made of foamed material inside the battery pack. Utilizing the property of foamed material to absorb and expand upon contact with water, the waterproof layer rapidly absorbs and expands when liquid enters the battery pack, filling the gaps and encasing the high-voltage components. This isolates the high-voltage components from the liquid, preventing the risk of insulation failure. Simultaneously, the waterproof layer prevents further penetration of liquid into the battery pack, avoiding further deterioration of the insulation environment, mitigating the risk of arcing and fire, and providing occupants with escape time. When no water enters the battery pack, the waterproof layer is in a contracted state and adheres to one or more of the following surfaces: the inner surface of the casing, the outer surface of the cell module, and the outer surface of the high-voltage circuit breaker unit. Its small volume does not affect the battery pack's electrical performance, structural performance, or thermal management performance.

[0021] The present invention also provides a method for preventing and monitoring internal leakage of a battery pack. The battery pack further includes a plurality of pressure detection elements arranged at intervals on the surface of a waterproof layer. The method includes: S1, acquiring the pressure detection signal output by each of the pressure detection elements; S2, performing data processing on the pressure value corresponding to each pressure detection signal, and determining whether there is internal leakage of the battery pack based on the data processing result.

[0022] This method enables automated protection and monitoring of internal leakage in the battery pack, thereby improving the safety performance of the battery pack. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A three-dimensional schematic diagram of the upper cover assembly provided in an embodiment of this application; Figure 2 A three-dimensional schematic diagram of the lower housing assembly provided in the embodiments of this application; Figure 3 This is a three-dimensional schematic diagram of the battery cell module provided in the embodiments of this application; Figure 4 A three-dimensional schematic diagram of a high-voltage circuit breaker unit provided in an embodiment of this application; Figure 5 A three-dimensional schematic diagram of a battery cell module and its waterproof layer provided in one embodiment of this application; Figure 6 for Figure 5 The schematic diagram of the waterproof layer and piezoelectric thin film sensor in the embodiment shown is as follows; Figure 7 A three-dimensional schematic diagram of a battery cell module and its waterproof layer provided in another embodiment of this application; Figure 8 This is a schematic diagram of the structure of the piezoelectric thin film sensor provided in the embodiments of this application; Figure 9 A flowchart illustrating the battery pack internal leakage protection and monitoring method provided in this application embodiment.

[0025] icon: 1-Top cover assembly; 11-Unit sealing cover; 12-Module sealing cover; 2-Lower housing assembly; 21-Lower housing body; 211-Frame; 212-Crossbeam; 213-Longitudinal beam; 22-Liquid cooling plate; 23-First structural adhesive layer; 24-First limiting adhesive strip; 3-Battery cell module; 31-Battery cell; 32-High voltage busbar; 33-Second structural adhesive layer; 34-Second limiting adhesive strip; 4-High-voltage circuit breaker unit; 5-Waterproof layer; 51-Installation groove; 52-Avoidance groove; 6-Piezoelectric thin film sensor; 61-Pressure sensing element array; 62-Insulating encapsulation layer. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that in the description of this invention, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] It should be noted that in the description of this invention, the terms "connection" and "installation" 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 direct connection or a connection through an intermediate medium; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] To address the technical problem of potential safety accidents caused by liquid leakage from the liquid cooling plate inside the battery pack, the first aspect of this application provides a battery pack, as described below. Figures 1 to 7 The battery includes a housing, and a cell module 3 and a high-voltage circuit breaker unit 4 disposed inside the housing; wherein, a waterproof layer 5 is provided in at least a portion of the gap between the housing and the cell module 3 and / or at least a portion of the surface of the high-voltage circuit breaker unit 4, and the waterproof layer 5 is made of foam material.

[0030] Combination Figure 1 and Figure 2The battery pack casing includes an upper cover assembly 1 and a lower casing assembly 2 that are interlocked and fitted together, forming an internal cavity. Typically, the lower casing assembly 2, the cell modules 3, the high-voltage wiring harness, and the upper cover assembly 1 are arranged sequentially from bottom to top. An electrical compartment is formed inside the battery pack casing, where the high-voltage circuit breaker unit 4 and the battery pack's control unit are located. The battery pack's control unit is responsible for receiving and processing various sensor signals, such as those from the temperature sensor and smoke sensor within the battery pack. Based on the processing results, it outputs control commands to the high-voltage circuit breaker unit 4. The high-voltage circuit breaker unit 4 is primarily responsible for controlling the high-voltage switching of the battery pack, energy distribution, and multiple safety protections.

[0031] This application incorporates a waterproof layer 5, primarily made of foamed material, inside the battery pack. Utilizing the property of foamed material to absorb and expand upon contact with water, the waterproof layer 5 rapidly absorbs and expands when liquid enters the battery pack, filling the gaps and encasing the high-voltage components. This isolates the high-voltage components from the liquid, preventing insulation failure. Simultaneously, the waterproof layer 5 prevents further penetration of liquid into the battery pack, avoiding further deterioration of the insulation environment, mitigating arcing and fire, and providing occupants with escape time. When no water enters the battery pack, the waterproof layer 5 is in a contracted state and adheres to one or more of the following surfaces: the inner surface of the casing, the outer surface of the cell module 3, and the outer surface of the high-voltage circuit breaker unit 4. Its small size does not affect the battery pack's electrical performance, structural performance, or thermal management performance.

[0032] Furthermore, referring to Figure 1 At least a portion of the internal area of ​​the top cover assembly 1 is provided with a waterproof layer 5 (not shown in the figure). Specifically, the top cover assembly 1 includes a unit sealing cover 11 disposed opposite to the high-voltage circuit breaker unit 4 and a module sealing cover 12 disposed opposite to the cell module 3, wherein at least a portion of the inner surface of the unit sealing cover 11 is provided with a waterproof layer 5, and at least a portion of the inner surface of the module sealing cover 12 is provided with a waterproof layer 5.

[0033] It should be noted that "at least part" means either all or a part of it. For example, the waterproof layer 5 can be provided only on the inner surface of the unit sealing cover 11 opposite to the high-pressure component, or the waterproof layer 5 can be provided on all the inner surfaces of the unit sealing cover 11.

[0034] When water enters the internal area of ​​the battery pack corresponding to the unit sealing cover 11, the waterproof layer 5 at the unit sealing cover 11 can absorb water and expand in time, preventing water from contacting the high-voltage components in the high-voltage circuit breaker unit 4. When water enters the internal area of ​​the battery pack corresponding to the module sealing cover 12, the waterproof layer 5 at the module sealing cover 12 can absorb water and expand in time, preventing water from contacting the high-voltage wiring harness and cell module 3 below.

[0035] In one alternative implementation, combined with Figure 1 , Figure 2 and Figure 5 The module sealing cover 12 and the cell module 3 need to be fixed together by a second structural adhesive layer 33. In this case, the waterproof layer 5 on both the module sealing cover 12 and the cell module 3 needs to avoid the area where the structural adhesive layer is laid, so as not to affect the coverage area of ​​the adhesive layer. In another optional embodiment, refer to... Figure 7 No structural adhesive layer is required to fix the module sealing cover 12 and the cell module 3. At this time, the waterproof layer 5 can be laid on the entire inner surface of the module sealing cover 12, and the waterproof layer 5 can also be laid on the entire surface of the cell module 3 facing the module sealing cover 12.

[0036] Furthermore, referring to Figure 2 The lower housing assembly 2 includes a lower housing body 21, a liquid cooling plate 22 disposed within the lower housing body 21, and a first structural adhesive layer 23 disposed on the liquid cooling plate 22. The first structural adhesive layer 23 is sandwiched between the liquid cooling plate 22 and the battery cell module 3. The lower housing assembly 2 has at least a partial waterproof layer 5 (not shown in the figure) disposed in the remaining internal area avoiding the first structural adhesive layer 23. A first limiting adhesive strip 24 is disposed around the first structural adhesive layer 23. The first structural adhesive layer 23 is used to connect the liquid cooling plate 22 and the battery cell module 3, serving to fix and conduct heat. The waterproof layer 5 on the lower housing assembly 2 and the waterproof layer 5 on the battery cell module 3 must both avoid the area where the first structural adhesive layer 23 is laid.

[0037] As an optional implementation, the lower shell body 21 includes a frame 211, and also includes a crossbeam 212 and a longitudinal beam 213 vertically distributed within the frame 211; a waterproof layer 5 may be selectively provided on the inner surface of the frame 211, the surface of the crossbeam 212, the surface of the longitudinal beam 213, and the bottom exposed surface of the lower shell assembly 2, excluding the first structural adhesive layer 23.

[0038] Reference Figure 3 , Figure 5 and Figure 7 At least a portion of the outer surface of the battery cell module 3 is provided with a waterproof layer 5.

[0039] As an optional implementation, the battery module 3 includes a battery cell 31 and a high-voltage return bus 32 disposed on one side of the battery cell 31, and the surface of the high-voltage return bus 32 is provided with a waterproof layer 5.

[0040] As an optional implementation, the cell module 3 further includes a second structural adhesive layer 33, which is disposed on the surface of the cell 31 near the upper cover assembly 1. A second limiting adhesive strip 34 is disposed around the second structural adhesive layer 33. In this case, the waterproof layer 5 on the surface of the cell module 3 facing the upper cover assembly 1 (generally the upper surface) needs to avoid the area where the second structural adhesive layer 33 is laid. As another optional implementation, refer to... Figure 7 The cell module 3 is not equipped with a second structural adhesive layer 33. At this time, the surface of the cell module 3 facing the upper cover assembly 1 can be completely covered with the waterproof layer 5.

[0041] In addition to the surface of the battery cell module 3 mentioned above, the remaining surfaces of the battery cell module 3 may also be covered with a waterproof layer 5 as required.

[0042] It should be noted that the waterproof layer 5 should not cover the cell's explosion-proof valve, so as not to affect the opening of the valve and venting of the cell in the event of thermal runaway.

[0043] Since the outer surface of the cell module 3, except for the structural adhesive layer, can be selectively covered with a waterproof layer 5, when a large amount of liquid enters the battery pack and the water ingress rate is high, the waterproof layer 5 at the lower housing assembly 2 may not have enough time to react. When the liquid level reaches the cell module 3, the waterproof layer 5 on the cell module 3 can prevent the liquid level from continuing to rise, thus avoiding contact between water and the high-voltage circuit and slowing down the damage to the high-voltage insulation in the battery pack.

[0044] Reference Figure 4 At least a portion of the outer surface of the high-voltage circuit breaker unit 4 is provided with a waterproof layer 5 (not shown in the figure). The high-voltage components inside the high-voltage circuit breaker unit 4 are densely packed, and the voltage is typically in the hundreds of volts; after the high-voltage circuit breaker unit 4 is completed, at least the exposed surfaces of the high-voltage components are covered with a waterproof layer 5. The outer surfaces of non-high-voltage components in the high-voltage circuit breaker unit 4 may not be provided with a waterproof layer 5.

[0045] Optionally, the waterproof layer 5 is at least partially a solid component with a specific shape; and / or, the waterproof layer 5 is at least partially formed by spraying.

[0046] The method of forming the waterproof layer 5 can be selected according to the morphology of its attachment surface. When the structure of a certain attachment surface is complex, it is preferable to form the waterproof layer 5 covering the attachment surface by spraying. When the structure of a certain attachment surface is relatively regular, the waterproof layer 5 can be formed by spraying, or the waterproof layer 5 can be prefabricated into a solid component adapted to the attachment surface. When the waterproof layer 5 is formed by spraying, specific areas (such as the areas where each structural adhesive layer is located) need to be shielded and protected during the spraying process to avoid the waterproof layer material being sprayed into these areas, which would cause other functional areas to be occupied by the waterproof layer material and affect their function. For example, the waterproof layer 5 on the outer surface of the high-voltage circuit breaker unit 4 is formed by spraying, while the waterproof layers 5 in other locations are prefabricated plate-shaped solid components adapted to their attachment surfaces. As another example, the entire waterproof layer 5 is formed by spraying.

[0047] Optionally: The waterproof layer 5 formed by spraying is naturally adhered to the corresponding attachment surface after curing; if the waterproof layer 5 is a solid component, it can be adhered to the corresponding attachment surface by thermally conductive structural adhesive.

[0048] Optionally, the foaming material includes silicone foam and / or polyurethane foam.

[0049] Optionally, the expansion rate of the foaming material is greater than or equal to 10. Using a foaming material with a high expansion rate can prevent the waterproof layer 5 from occupying too much internal space of the battery pack before foaming, thus affecting battery performance.

[0050] Before preparing the waterproof layer 5, the initial dimensions of the waterproof layer 5 are calculated by calculating the void size within the battery pack and the expansion rate of the foaming material. Taking the waterproof layer 5 as a plate-shaped solid component or as a roughly plate-shaped structure after spraying and curing as an example, the initial volume of the waterproof layer 5 = the volume of the voids it contains / the foaming rate of the waterproof layer 5, and the initial thickness of the waterproof layer 5 = the initial volume of the waterproof layer 5 / the area of ​​the maximum surface of the waterproof layer 5. In other words, the gaps where the waterproof layer 5 is located only allow for expansion in the thickness direction of the waterproof layer 5, and the dimensions of the waterproof layer 5 in its length and width directions are constrained by the boundaries of the gaps it contains, so that the waterproof layer 5 mainly expands and deforms along its thickness direction after absorbing water.

[0051] During the battery pack assembly process, the waterproof layer 5 is sprayed on a specific surface using a spraying device according to its initial dimensions; or, the waterproof layer 5 is prefabricated into a solid component of a specific size, and then attached to the corresponding position during the battery pack assembly process.

[0052] Optionally, the waterproof layer 5 is doped with functional fillers, including one or more of thermally conductive fillers, flame-retardant fillers, and color-changing fillers. Specifically: the thermally conductive filler improves the thermal conductivity of the waterproof layer 5, preventing heat dissipation from being affected by the waterproof layer 5 covering the surface of heat-generating devices; the flame-retardant filler provides flame retardant properties, further enhancing the safety of the battery pack; and the color-changing filler changes color upon contact with water, allowing personnel to quickly locate leaks during maintenance.

[0053] Optionally, the thermally conductive filler includes at least one of ceramic powder, alumina powder, thermally conductive silicone grease, thermally conductive gel, and thermally conductive potting compound. The thermal conductivity and amount of the thermally conductive filler are added based on the results of system thermal simulation performance tests, so that the waterproof layer 5 has a certain heat dissipation performance, thereby not affecting the operation of the battery system.

[0054] Optionally, the flame-retardant filler includes at least one of ceramicized composite powder, aluminum hydroxide, and magnesium hydroxide.

[0055] The preferred functional filler is an insulating powder filler. Powder fillers have better compatibility with foaming materials, ensuring that the foaming materials possess stable foaming process performance.

[0056] Theoretically, the proportion of functional fillers should not exceed 50% of the foamed material. If the proportion of functional fillers is greater than 50% after thermal simulation or actual measurement, the proportion of foamed material in the battery pack can be further increased by spraying foamed material separately into the gaps of the battery pack.

[0057] Since the high-voltage return bus 32 and the high-voltage components in the high-voltage circuit breaker unit 4 are heat-generating devices, the waterproof layer 5 covering the aforementioned surfaces is filled with thermally conductive filler. The waterproof layer 5 in other locations may not require thermally conductive filler.

[0058] As an optional implementation method, continue to refer to Figures 5 to 7 The battery pack also includes a pressure sensing element array 61 disposed on the surface of the waterproof layer 5. The pressure sensing element array 61 is composed of a number of pressure sensing elements arranged at intervals. The pressure sensing element array 61 and the high-voltage circuit breaker unit 4 are both electrically connected to the control unit of the battery pack.

[0059] Based on the above structure, the pressure detection element array 61 is preferably arranged on the waterproof layer 5 located on the cell module 3, and preferably on the side of the waterproof layer 5 that is horizontal and away from the cell module 3. Compared with arranging the pressure detection element array 61 at the bottom of the cell module 3, the advantages of the above structure are: the pressure detection element array 61 is less susceptible to bottom impact, reducing the probability of false triggering; and it is less likely to be soaked by leaked liquid, resulting in a very low risk of seal failure. Compared with arranging the pressure detection element array 61 at the top of the cell module 3, the advantages of the above structure are: the expansion of the waterproof layer 5 can be identified before the leaked liquid spreads along the waterproof layer 5 to the top of the cell module 3, resulting in a more timely response.

[0060] The pressure detection element array 61 forms several monitoring points on the waterproof layer 5, which can monitor the pressure value changes of each monitoring point in real time. When leakage occurs inside the battery pack, the waterproof layer 5 absorbs water and undergoes local volume expansion, thereby applying pressure to the pressure detection elements set in the expansion area. Each pressure detection element collects the pressure detection signal of the corresponding monitoring point and feeds it back to the control unit of the battery pack. The control unit processes the pressure value corresponding to the pressure detection signal and uses the change in pressure value to feed back the degree of expansion and water absorption of the waterproof layer 5 and the expansion location, thereby indirectly judging the leakage situation inside the battery pack and realizing real-time monitoring of the degree and location of leakage.

[0061] As an optional implementation method, combined with Figure 8 The battery pack also includes a piezoelectric thin-film sensor 6 disposed on the surface of the waterproof layer 5. The piezoelectric thin-film sensor 6 includes two sealed insulating encapsulation layers 62 and a pressure sensing element array 61 disposed between the two insulating encapsulation layers 62. The wiring port of the piezoelectric thin-film sensor 6 is generally arranged upwards; on the one hand, the wiring port of the piezoelectric thin-film sensor 6 is arranged away from the liquid cooling plate 22, making it less likely to come into contact with leaking liquid and reducing the probability of insulation seal failure; on the other hand, the low-voltage wiring harness in the battery pack is generally arranged above the module, and the wiring port of the piezoelectric thin-film sensor 6 is arranged facing the low-voltage wiring harness for easy wiring.

[0062] The piezoelectric thin-film sensor 6 has the following advantages: First, the sensor is thin, light, and flexible, allowing it to be fitted into narrow gaps inside the battery pack without occupying effective energy storage space, and it has good assembly adaptability. Second, it is easy to achieve array deployment, forming multiple independent detection points, which can acquire pressure signals from multiple locations inside the battery pack, identify the pressure distribution, and easily distinguish between pressure changes caused by single-point impact and leakage diffusion, providing a multi-point data basis for preventing accidental touches. Third, it has a fast response speed and high sensitivity, enabling dynamic monitoring of the degree of leakage. Fourth, the overall structure is a thin-film layered encapsulation structure, which is simple and has its own insulation and sealing function for internal detection elements. Fifth, the piezoelectric thin-film sensor 6 can be attached to the waterproof layer 5, and the two are combined to form an integrated intelligent sensing component.

[0063] It should be noted that the arrangement of the pressure sensing elements in the piezoelectric thin film sensor 6 is not limited to... Figure 8 As shown in the diagram. For example, the pressure sensing elements in the piezoelectric thin film sensor 6 are arranged in n rows and q columns, where n≥1 and q≥4; where the value of n is adjusted according to the module thickness and the value of q is adjusted according to the module length.

[0064] As an optional implementation method, refer to Figure 5 and Figure 6 The battery pack has multiple waterproof layers 5 inside, including a first waterproof layer. The first waterproof layer is a solid component and is attached to one side of the cell module 3 along the horizontal direction. A piezoelectric thin film sensor 6 is attached to the first waterproof layer. The first waterproof layer and the piezoelectric thin film sensor 6 together form an integrated intelligent sensing component. The first waterproof layer is roughly U-shaped, flat, or L-shaped.

[0065] The first waterproof layer can be one or two. For example... Figure 5 As shown, when there are two first waterproof layers, one first waterproof layer is applied to the surface of the high-voltage busbar 32, and the other first waterproof layer is applied to a surface opposite to the high-voltage busbar 32. When there is only one first waterproof layer, it is applied to the surface of the high-voltage busbar 32.

[0066] Preferably, there are two first waterproof layers, which are disposed on opposite sides of the battery cell module 3 along the horizontal direction. A piezoelectric thin-film sensor 6 is attached to the horizontal surface of each first waterproof layer, away from the battery cell module 3. The piezoelectric thin-film sensors 6 on both sides of the battery cell module 3 can more accurately locate the leak. For example, if the pressure value detected by pressure detection element A is greater than the pressure value detected by pressure detection element B among two adjacent pressure detection elements, then theoretically the leak location is closer to pressure detection element A. Based on this principle, the detection signals from all pressure detection elements on both sides of the battery cell module 3 are comprehensively collected, and the most likely leak location is determined through simulation fitting calculations, facilitating quick troubleshooting by operators.

[0067] As an optional implementation, a mounting groove 51 is provided on the surface of the first waterproof layer along the horizontal direction and away from the battery cell module 3, and the piezoelectric thin film sensor 6 is disposed in the mounting groove 51; the bottom surface of the mounting groove 51 is respectively provided with a relief groove 52 corresponding to the position of each pressure detection element. Through the above arrangement, a gap exists between the first waterproof layer and the pressure detection element when it does not absorb water and expand, thereby reducing the probability of the pressure detection element being accidentally activated.

[0068] A second aspect of this application provides a vehicle that includes the battery pack provided in any of the above embodiments. This vehicle possesses at least all the technical features and effects of the aforementioned battery pack, which will not be repeated here.

[0069] A third aspect of this application provides a method for preventing and monitoring internal leakage of a battery pack, referring to... Figure 9 The method includes: S1. Obtain the pressure detection signals output by each pressure detection element; S2. Process the pressure values ​​corresponding to each pressure detection signal, and determine whether there is leakage inside the battery pack based on the data processing results. Step S2 includes: Compare the pressure value corresponding to each pressure detection signal with the first preset pressure threshold P1; If the pressure value is less than the preset number N1 (e.g., 1 to 5) but greater than the first preset pressure threshold P1, it is determined whether there is a false triggering situation; If it is determined that there is no accidental contact, it is determined that there is leakage inside the battery pack; If the pressure value of a number of items not less than the preset number N1 (e.g., 5 or more) is greater than the first preset pressure threshold P1, then regardless of whether there is a false triggering, it is determined that there is leakage inside the battery pack. If a false touch is detected, return to step S1; S3. When it is determined that there is leakage inside the battery pack, output a first-level warning signal to the user; for example, output a text warning and / or icon warning on the vehicle display screen to indicate that there may be a leakage fault in the battery pack and remind the user to have it repaired in time. S4. When at least one pressure value is greater than the third preset pressure threshold P3, P3>P1, a secondary warning signal is output to the user and the high-voltage circuit of the battery pack is cut off to protect the safety of the vehicle's power system.

[0070] In step S2, determining whether there is a false touch includes: a) comparing whether the duration of the pressure detection signal corresponding to the pressure value being greater than the first preset pressure threshold is greater than the preset duration; and / or, b) comparing whether the rate of change of the pressure value is greater than the preset rate of change; and / or, c) comparing whether the pressure value corresponding to the adjacent pressure detection unit is greater than the second preset pressure threshold P2, where P2 < P1; and determining whether there is a false touch based on the comparison results.

[0071] If the comparison results of steps a, b, and c are all yes, then it is determined that there is no accidental touch; if at least one of the comparison results is no, then it is determined that there is an accidental touch.

[0072] This embodiment uses three conditions—signal duration, pressure change rate, and pressure of adjacent detection units—to jointly determine the prevention of accidental triggering, thereby filtering out various interference signals during battery pack operation and distinguishing between actual leakage conditions and accidental triggering signals.

[0073] The determination of accidental touch in this embodiment includes the following aspects: (1) Judgment based on signal duration: Vehicle bumps and impacts during driving generate instantaneous pressure, but this type of disturbance pressure lasts for a very short time. However, when a leak occurs, the coolant is continuously absorbed by the waterproof layer 5, and the pressure caused by the expansion of the waterproof layer 5 is continuous. The duration of the signal with a pressure value greater than P1 is compared with the preset duration T1. Only when the pressure exceeding the threshold is maintained for the preset duration is it considered a valid signal, thereby filtering out false triggers caused by instantaneous impacts.

[0074] (2) Judgment based on the rate of change of pressure value: External impacts and collisions involve instantaneous loading, causing a rapid change in pressure and a large pressure change rate. In contrast, leakage involves slow liquid absorption, with the waterproof layer 5 gradually expanding and increasing pressure, resulting in a smoother pressure change and a relatively small pressure change rate within a preset range. By comparing the pressure change rates, we can distinguish between the two different pressure generation mechanisms: instantaneous mechanical impact and slow expansion from leakage, further eliminating the possibility of impact interference.

[0075] (3) Based on the collaborative judgment of pressure values ​​of adjacent detection units: In the event of a leak, the coolant will gradually spread across the waterproof layer 5, causing multiple adjacent detection units on the array to detect pressure signals. By using the pressure from adjacent detection units for collaborative verification, a single-point abnormal signal is directly identified as interference, while only when multiple points simultaneously detect pressure is it considered a valid fault signal, thus eliminating misjudgments caused by single-point disturbances.

[0076] By simultaneously verifying the above three aspects, the signal is identified from three dimensions: signal duration, pressure increase rate, and pressure distribution range. This significantly reduces the probability of misjudgment caused by vibration, impact, and local disturbance, and improves the reliability of leak detection.

[0077] Before the battery pack is manufactured and shipped, the calibration of various preset thresholds is completed in advance. Combining the structural parameters of the battery pack, the water absorption and expansion characteristics of the waterproof layer 5, and the response characteristics of the piezoelectric thin film sensor 6, multiple sets of simulation tests are conducted to determine the reasonable range of values ​​for the first, second, and third preset pressure thresholds, preset duration, and preset rate of change thresholds.

[0078] Considering that temperature changes may affect the detection accuracy of the pressure detection unit, temperature-pressure calibration is performed on the pressure detection unit before battery pack manufacturing. Under different set temperature environments, a known standard pressure is applied to the pressure detection unit, and the output signal of the pressure detection unit at each temperature point is collected. A calibration mapping relationship between temperature, actual pressure, and sensor output signal is established, and this calibration mapping relationship is stored in the storage unit that executes the monitoring logic.

[0079] During the actual operation of the battery pack, the control unit acquires the temperature signal from the internal temperature sensor of the battery pack, retrieves the pre-stored calibration mapping relationship, and uses the temperature parameters to compensate and correct the pressure detection signal output by the pressure detection unit. This counteracts the piezoelectric output drift caused by temperature changes, eliminates the detection deviation caused by temperature changes, and avoids misjudgment or missed judgment of leakage due to temperature fluctuations.

[0080] Furthermore, step S3 also includes: when it is determined that there is leakage inside the battery pack, predicting the location of the leakage inside the battery pack based on the data processing results, and outputting the leakage location to the vehicle display screen for display, so as to show the possible leakage location to the user in a visual manner.

[0081] In summary, this application incorporates a waterproof layer 5, primarily made of foamed material, within the internal gaps of the battery pack. This waterproof layer 5 rapidly absorbs water and expands when liquid enters the battery pack, isolating high-voltage components from the liquid and preventing the risk of insulation failure. It also mitigates the risk of arcing and fire. A pressure detection element array 61 is attached to the surface of the waterproof layer 5, allowing for real-time monitoring of its expansion. This enables the determination of whether leakage has occurred inside the battery pack and predicts the location of the leak, facilitating rapid fault diagnosis. The method provided by this application simultaneously achieves leakage protection and monitoring. It can identify leakage faults, predict the leakage location, and output early warning signals in the initial stage of leakage within the battery pack. Furthermore, it provides power-off protection in the severe stage of leakage, reducing the safety hazards caused by coolant seeping into high-voltage components and improving the safety performance of the battery pack.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery pack, characterized in that, It includes a housing, and a battery cell module and a high-voltage circuit breaker unit disposed inside the housing; A waterproof layer is provided in at least a portion of the gap between the housing and the battery cell module and / or on at least a portion of the surface of the high-voltage circuit breaker unit, wherein the waterproof layer is made of foam material.

2. The battery pack according to claim 1, characterized in that, The housing includes an upper cover assembly and a lower housing assembly that are interlocked and installed together, and the waterproof layer is provided on the upper cover assembly and / or the lower housing assembly.

3. The battery pack according to claim 2, characterized in that, The waterproof layer is provided in at least a portion of the interior area of ​​the top cover assembly; And / or, the lower housing assembly includes a lower housing body, a liquid cooling plate disposed within the lower housing body, and a first structural adhesive layer disposed on the liquid cooling plate, the first structural adhesive layer being sandwiched between the liquid cooling plate and the battery cell module, and the lower housing assembly having at least a partial waterproof layer disposed in the remaining internal area avoiding the first structural adhesive layer.

4. The battery pack according to claim 1, characterized in that, The waterproof layer is provided on at least a portion of the outer surface of the battery cell module; The waterproof layer is provided on at least a portion of the outer surface of the high-voltage circuit breaker unit.

5. The battery pack according to claim 1, characterized in that, The waterproof layer is at least partially a solid component with a specific shape; And / or, the waterproof layer is at least partially formed by spraying.

6. The battery pack according to claim 1, characterized in that, The foaming material includes silicone foaming material and / or polyurethane foam; And / or, the expansion rate of the foamed material is greater than or equal to 10.

7. The battery pack according to claim 1, characterized in that, The waterproof layer contains functional fillers, which include one or more of thermally conductive fillers, flame-retardant fillers, and color-changing fillers.

8. The battery pack according to claim 7, characterized in that, The thermally conductive filler includes at least one of ceramic powder, alumina powder, thermally conductive silicone grease, thermally conductive gel, and thermally conductive potting compound; And / or, the flame-retardant filler includes at least one of ceramicized composite powder, aluminum hydroxide, and magnesium hydroxide; And / or, the proportion of the functional filler is not greater than 50% of the proportion of the foaming material.

9. The battery pack according to any one of claims 1 to 8, characterized in that, It also includes a pressure sensing element array disposed on the surface of the waterproof layer, the pressure sensing element array being composed of a plurality of pressure sensing elements arranged at intervals; Both the pressure sensing element array and the high-voltage circuit breaker unit are electrically connected to the control unit of the battery pack.

10. The battery pack according to claim 9, characterized in that, It also includes a piezoelectric thin film sensor disposed on the surface of the waterproof layer, the piezoelectric thin film sensor comprising two sealed insulating encapsulation layers and the pressure sensing element array disposed between the two insulating encapsulation layers.

11. A vehicle, characterized in that, Includes the battery pack as described in any one of claims 1 to 10.

12. A method for preventing and monitoring internal leakage of a battery pack, characterized in that, Applied to the battery pack of claim 9 or 10, the method includes: S1. Obtain the pressure detection signal output by each of the pressure detection elements; S2. Process the pressure values ​​corresponding to each pressure detection signal, and determine whether there is leakage inside the battery pack based on the data processing results.

13. The method for preventing and monitoring internal leakage of a battery pack according to claim 12, characterized in that, Step S2 includes: Compare the pressure value corresponding to each pressure detection signal with the first preset pressure threshold. If the pressure value below the preset number is greater than the first preset pressure threshold, it is determined whether there is a false triggering situation; If it is determined that there is no accidental touch or the pressure value of no less than a preset number is greater than the first preset pressure threshold, it is determined that there is leakage inside the battery pack.

14. The method for preventing and monitoring internal leakage of a battery pack according to claim 13, characterized in that, The determination of whether a false touch has occurred includes: The duration of the pressure detection signal corresponding to a pressure value greater than a first preset pressure threshold is compared to whether it is greater than a preset duration; and / or, the rate of change of the pressure value is compared to whether it is greater than a preset rate of change; and / or, the pressure value corresponding to an adjacent pressure detection unit is compared to whether it is greater than a second preset pressure threshold, wherein the second preset pressure threshold is less than the first preset pressure threshold. The comparison results will determine whether there is any accidental touch.

15. The method for preventing and monitoring internal leakage of a battery pack according to claim 13, characterized in that, Also includes: S3. When it is determined that there is leakage inside the battery pack, output a first-level warning signal to the user, and / or predict the location of the leakage inside the battery pack and output it to the vehicle display screen for display. S4. When at least one pressure value is greater than a third preset pressure threshold, and the third preset pressure threshold is greater than the first preset pressure threshold, a secondary warning signal is output to the user and the high-voltage circuit of the battery pack is cut off.

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