Heat dissipation and swelling composite soft package battery pack and electric power tool

Abstract

The utility model provides a heat dissipation suction composite soft package battery pack and electric tool belong to electric tool technical field, the heat dissipation suction composite soft package battery pack includes: shell and soft package battery group, be provided with the electric core support in the shell, and the electric core support and shell inner wall constitute the accommodation cavity for accommodating soft package battery group, and soft package battery group includes a plurality of soft package electric core who sets up in the accommodation cavity, and is equipped with heat conduction buffer complex between two soft package electric core, and heat conduction buffer complex size matches the size of soft package electric core big face, and heat conduction buffer complex includes heat conduction pad and elastic buffer piece, and heat conduction pad is set up with through -hole along the thickness direction, and elastic buffer piece is worn in through -hole, and the uncompressed thickness of elastic buffer piece is greater than the thickness of heat conduction pad, and in soft package battery group, heat conduction pad and elastic buffer piece respectively with the big face of soft package electric core are face contact. The utility model can effectively absorb and restrain the expansion force of soft package electric core in the cyclic use, prevents the excessive deformation damage of soft package electric core.

Description

Technical Field

[0001] This utility model relates to a heat dissipation and swelling composite soft-pack battery pack and an electric tool, belonging to the field of electric tool technology. Background Technology

[0002] As power tools evolve towards higher power, miniaturization, and lighter weight, increasingly higher demands are being placed on the energy density, output power, and cycle life of power batteries. Polymer lithium-ion cells (pouch cells) are considered an ideal replacement for traditional cylindrical cells due to their higher energy density, superior weight characteristics, and better thermal management interface. However, their application in the power tool field has long faced two irreconcilable core technological bottlenecks.

[0003] First, there is a conflict between heat dissipation and mechanical constraints. Power tools operate at extremely high currents (often exceeding 20A, with peak values ​​reaching 80-100A), leading to concentrated heat generation within the battery cell. The large surface area (perpendicular to the thickness of the pouch cell) is the primary heat dissipation interface. Currently, those skilled in the art simply use the solution found in cylindrical batteries: filling the spaces between cells with silicone thermal pads to dissipate heat from the large surface area of ​​the cell. While this does conduct heat, the rigid or semi-rigid support structure of the pouch battery pack severely restricts the inevitable, irreversible swelling (bulging) of the pouch cells throughout their lifespan. This results in enormous stress within the cell, rapidly accelerating capacity decay and creating serious safety hazards such as leakage and short circuits.

[0004] Secondly, the technological path is stuck in a vicious cycle; if elastic silicone foam is used instead of silicone thermal pad to alleviate the aforementioned swelling problem, the extremely low thermal conductivity of elastic silicone foam (usually <0.1W / (m·K)) will prevent heat from being dissipated, and the battery cell will operate at high temperature, which will also seriously damage its lifespan and safety.

[0005] Although pouch cells have inherent advantages such as high energy density, flexible shape design, light weight, and low internal resistance, their low mechanical strength and susceptibility to expansion and deformation during charging and discharging hinder their application in the field of power tools where vibration and impact are high. Utility Model Content

[0006] To address the aforementioned shortcomings of existing technologies, this invention proposes a heat dissipation and swelling absorption composite soft-pack battery pack and power tool. This pack effectively absorbs and suppresses the expansion force of the soft-pack battery cells during cyclic use, preventing excessive deformation and damage to the cells. It also avoids the risks of bulging and thermal runaway when the soft-pack battery is used in power tools subject to high vibration and impact, thus leveraging its advantages of high energy density, flexible shape design, light weight, and low internal resistance.

[0007] This utility model relates to a heat dissipation and swelling composite soft-pack battery pack, comprising:

[0008] shell;

[0009] The cell support is housed within the casing; together with the inner wall of the casing, it forms a cavity for accommodating the pouch battery pack.

[0010] The pouch battery pack includes several pouch cells stacked in a receiving cavity, and each pouch cell is provided with tabs; a thermally conductive buffer composite is provided between two adjacent pouch cells, and the size of the thermally conductive buffer composite matches the size of the large surface of the pouch cell.

[0011] The thermally conductive buffer composite includes a thermally conductive pad and an elastic buffer; the thermally conductive pad has a through hole along its thickness direction, and the elastic buffer is inserted through the through hole, with the uncompressed thickness of the elastic buffer being greater than the thickness of the thermally conductive pad; in the pouch battery pack, the thermally conductive pad and the elastic buffer are in surface contact with the large surface of the pouch cell.

[0012] The second aspect of this utility model relates to an electric tool powered by the aforementioned heat dissipation and expansion-absorbing composite soft-pack battery pack. The electric tool can be any one of an electric drill, electric hammer, angle grinder, sander, reciprocating saw, electric circular saw, electric wrench, electric screwdriver, pruning machine, chainsaw, or lawnmower.

[0013] Compared with the prior art, the present invention has the following technical effects:

[0014] 1. Pre-compression buffer: The elastic buffer provides a buffer space for the expansion of the soft-pack battery cell. By being further compressed, it absorbs the expansion force generated during the charging and discharging process of the soft-pack battery cell, effectively counteracts the expansion, prevents damage to the soft-pack battery cell structure, and improves the lifespan and safety of the soft-pack battery cell.

[0015] 2. Maintaining Interface Contact: When the thickness of the pouch cell is reduced due to depletion, especially during long-term use, or when the pouch cell expands when fully charged and thins due to depletion, resulting in frequent and large thickness changes, the rebound force of the elastic buffer can quickly compensate for areas of significant deformation in the pouch cell (the central area of ​​the large surface of the pouch cell). In areas where deformation is not significant, the thermal pad itself has a certain compressibility, which can compensate for small deformations of the pouch cell, ensuring that the thermal pad and the surface of the pouch cell are always in close contact. This avoids the problem of reduced heat dissipation performance due to air gaps, ensuring the long-term reliability of thermal management and guaranteeing the lifespan and safety of the pouch cell.

[0016] 3. Simple assembly process: The soft-pack battery cell and the thermally conductive buffer composite are stacked sequentially on the battery cell bracket. The modular design makes the assembly process simple and efficient, which is conducive to large-scale production. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0018] Figure 2 This is an exploded structural diagram of an embodiment of the present utility model;

[0019] Figure 3 This is a schematic diagram of the structure of the battery cell support in an embodiment of this utility model;

[0020] Figure 4 This is a schematic diagram of the structure of the thermally conductive buffer composite in the embodiments of this utility model;

[0021] In the diagram: 1. Upper housing; 2. Lower housing; 3. Power management protection board; 4. Cell support; 5. Thermal pad; 6. Soft-pack cell; 7. Elastic buffer; 41. Top plate; 42. Side plate; 43. Support leg; 44. Notch. Detailed Implementation

[0022] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0023] It should be noted that, in specific embodiments, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model. They 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, and therefore should not be construed as a limitation on this utility model. Terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly defined, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] like Figure 1 , Figure 2 and Figure 4 As shown, this utility model embodiment relates to a heat dissipation and swelling composite soft-pack battery pack, comprising:

[0025] shell;

[0026] The cell support 4 is set in the outer casing; together with the inner wall of the outer casing, it forms a cavity for accommodating the soft-pack battery pack, which provides limiting support for the soft-pack battery pack and can adapt to the harsh working conditions of high vibration and strong impact of power tools.

[0027] The pouch battery pack includes several pouch cells 6 stacked in a receiving cavity; a thermally conductive buffer composite is provided between two adjacent pouch cells 6, and the size of the thermally conductive buffer composite matches the size of the large surface of the pouch cell. Matching means that the two have the same size projected in the thickness direction of the pouch cell.

[0028] The thermally conductive buffer composite includes a thermally conductive pad 5 and an elastic buffer 7. The thermally conductive pad 5 has a through hole along its thickness direction, and the elastic buffer 7 is inserted through the through hole. The uncompressed thickness of the elastic buffer 7 is greater than the thickness of the thermally conductive pad 5. In the soft-pack battery pack, the thermally conductive pad 5 and the elastic buffer 7 are in surface contact with the large surface of the soft-pack battery cell 6. Preferably, the thermally conductive pad 5 is a thermally conductive silicone pad, and the elastic buffer 7 is silicone foam or rubber.

[0029] For some specific implementation plans, such as Figure 1 and Figure 2 As shown, the outer shell is composed of an upper shell 1 and a lower shell 2, which are fixedly connected by screws. The upper and lower shells adopt an upper and lower combined shell structure, which facilitates assembly operations inside the shell.

[0030] As for the cell bracket 4, it can act as a heat spreader to evenly distribute heat, making the temperature distribution more uniform and avoiding local overheating. While ensuring the stability of the bracket structure during the charging and discharging process, it also improves the heat conduction performance, ensuring that heat can be quickly conducted to the outer shell. Through heat exchange between the outer shell and the air, it prevents the cell temperature from soaring, buys time for the heat dissipation system to react, and ultimately controls the core temperature of the soft-pack cell at a low level.

[0031] For some specific implementation schemes, the battery cell bracket 4 is made of metal and is anodized; preferably, 6063 aluminum alloy is used, which has a tensile strength of 195-240 MPa, a specific heat capacity of 890-910 J / (kg·K), and a thermal conductivity of 200-218 W / (m·K), meeting the requirements for heat conduction, vibration resistance and impact resistance.

[0032] For some specific implementation schemes, the battery cell support 4 can also be made of high-strength plastic filled with inorganic thermally conductive filler; the high-strength plastic is selected from polyetheretherketone, polycarbonate, polyphenylene sulfide, polyamide, and glass fiber reinforced thermosetting plastics; the inorganic thermally conductive filler is selected from at least one of magnesium oxide, aluminum oxide, aluminum nitride, boron nitride, and silicon carbide. Preferably, the outer shell is made of the same material as the battery cell support 4. For example, the outer shell and the battery cell support 4 can be made of PA6 filled with aluminum oxide, with a tensile strength of 55-65 MPa, a specific heat capacity of approximately 1300-1700 J / (kg·K), and a thermal conductivity of approximately 1.4-6.5 W / (m·K), which can also meet the requirements of thermal conductivity, vibration resistance, and impact resistance. More preferably, the outer shell can also be covered with insulating rubber to improve drop resistance and prevent personal injury caused by excessive local temperature.

[0033] For some specific implementation plans, such as Figure 2 and Figure 3 As shown, the cell support 4 includes a top plate 41 and a side plate 42. The top plate 41 is an inverted tray structure used to limit and fix the soft-pack battery pack. The side plate 42 is set on one side of the top plate 41, and has a tab slot and a tab connecting piece corresponding to the tab of the soft-pack battery cell 6. The tabs face the same side, pass through the tab slot, and are welded and fixed to the tab connecting piece. Preferably, the top plate 41 is also provided with a number of support legs 43, which abut against the inner wall of the outer shell. For the cell support 4 made of thermally conductive material, on the one hand, the heat conduction path is increased, and on the other hand, a more solid support and positioning is provided for the soft-pack battery pack. Combined with the outer shell, the overall structure of the soft-pack battery pack is more robust. Combined with the thermally conductive buffer composite, it can better withstand vibration and impact. More preferably, a pair of support legs 43 are provided, and a notch 44 is provided between the two support legs 43 to facilitate the loading and unloading of the soft-pack battery cell 6.

[0034] For some specific implementation plans, such as Figure 2 As shown, the cell support 4 is also provided with a power management protection board 3 on the side away from the soft-pack battery pack. The power management protection board 3 is electrically connected to the tabs of the soft-pack battery cell 6 and is used to realize the charging and discharging management, status monitoring and power protection functions of the soft-pack battery pack.

[0035] For some specific implementation schemes, in the thickness direction of the soft-pack cell 6, a thermally conductive buffer composite is provided between the soft-pack battery pack, the cell support 4, and the outer shell to increase the thermally conductive contact area and improve the thermal conductivity.

[0036] For some specific implementation schemes, a thermal pad (not shown in the figure) is provided between the side of the cell support without a side plate (e.g., between the two support legs 43, and between the support leg 43 and the side plate 42) and the outer shell. This further increases the thermal conduction path and thermal contact area in the thickness direction of the soft-pack cell, thereby maximizing the thermal contact area and reducing thermal resistance.

[0037] For some specific implementation plans, such as Figure 4 As shown, the through hole is a single hole located in the center of the thermal pad 5. This is because the expansion rate of the central region of the pouch cell 6 is significantly higher than that of other regions when it expands. Corresponding to this high expansion rate region, an elastic buffer pad is installed on the thermal pad 5 through a hole to counteract the expansion of the pouch cell 6, preventing damage caused by compression from adjacent pouch cells after expansion, thus better protecting the pouch cell 6 and improving safety performance. For example, for a square pouch cell, the cross-section of its through hole is rectangular, with the side length of any side of the rectangular opening being 3 / 5 to 4 / 5 of the side length of the corresponding pouch cell. The distance from the through hole to the two parallel sides of the pouch cell is equal. That is, the opening area of ​​the through hole is 36% to 64% of the large surface area of ​​the pouch cell, and more preferably, the opening area is 50% of the large surface area of ​​the pouch cell. For different pouch cells, the opening area can be adjusted within the above data range according to their expansion performance to obtain better heat dissipation or expansion absorption capacity.

[0038] Taking one assembly method of a soft-pack battery pack in a cordless electric drill as an example, the configuration includes an integrally molded plastic cell bracket 4, five soft-pack cells 6, six thermally conductive buffer composites, a power management protection board 3, and an outer shell consisting of an upper shell 1 and a lower shell 2. First, the first thermally conductive buffer composite is horizontally positioned inside the top plate 41 of the cell support 4. Then, the first soft-pack cell 6 is positioned on the first thermally conductive buffer composite. After that, the thermally conductive buffer composite and the soft-pack cell 6 are stacked in sequence, with the soft-pack cell 6 and the thermally conductive buffer composite matching in shape and size and without gaps. The last thermally conductive buffer composite is attached to the surface of the soft-pack cell 6 away from the top plate 41. After assembly, the cell tabs are bent to the predetermined position and welded to the tab connecting piece on the side plate 42. Then, the power management protection board 3 is installed on the top plate 41 of the cell support 4 with screws and placed into the lower housing, so that the last thermally conductive buffer composite fits into the lower housing 2. Finally, the upper housing 1 is closed and locked with screws, thus completing the assembly of the soft-pack battery pack. If necessary, thermal paste can be applied before closing the upper housing 1 to improve the thermal conductivity between the cell support and the outer shell.

[0039] Taking the above-mentioned combined upper and lower shell structure as an example, the two large surfaces of any soft-pack battery cell are made to fit the soft, horizontally arranged thermally conductive buffer composite with another soft-pack battery cell, or battery cell bracket, or shell through the back adhesive, thereby maximizing the horizontal thermal contact area. Combined with the battery cell bracket support legs and side thermal pads, the heat conduction path is further optimized and the lateral thermal conduction capability is improved.

[0040] The heat generated by the pouch cell is first conducted horizontally through the thermal pad, and then quickly transferred to the lower shell, the integrated cell support, and the side thermal pads, which have considerable specific heat capacity and thermal conductivity. Finally, the heat is exchanged with the air through the outer shell to achieve rapid heat dissipation.

[0041] Most importantly, in this embodiment of the invention, the elastic buffer provides a buffer space for the expansion of the pouch cell. By being further compressed, it absorbs the expansion force generated during the charging and discharging of the pouch cell, preventing damage to the pouch cell structure. When the pouch cell is depleted and its thickness is reduced, especially in cases of long-term use, expansion after full charging and thinning due to depletion, and frequent and large changes in thickness, the rebound force of the elastic buffer can quickly compensate for the areas of significant deformation (central area) in the pouch cell. In areas with less significant deformation (peripheral area), the thermal pad itself has a certain compressibility, which can compensate for the small deformation of the pouch cell, ensuring that the thermal pad and the surface of the pouch cell are always in close contact. This avoids the problem of reduced heat dissipation performance due to air gaps and ensures the long-term reliability of thermal management.

[0042] It should be emphasized that the above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A heat-dissipating and swelling-absorbing composite soft-pack battery pack, comprising: The outer casing and the pouch battery pack with tabs are characterized in that, The outer casing is provided with a cell support, and the cell support and the inner wall of the outer casing form a receiving cavity for accommodating the soft-pack battery pack. The pouch battery pack includes several pouch cells stacked in a receiving cavity; a thermally conductive buffer composite is provided between two adjacent pouch cells, and the size of the thermally conductive buffer composite matches the size of the large surface of the pouch cell; The thermally conductive buffer composite includes a thermally conductive pad and an elastic buffer; the thermally conductive pad has a through hole along its thickness direction, and the elastic buffer is inserted through the through hole, with the uncompressed thickness of the elastic buffer being greater than the thickness of the thermally conductive pad; in the pouch battery pack, the thermally conductive pad and the elastic buffer are in surface contact with the large surface of the pouch cell.

2. The heat dissipation and swelling composite soft-pack battery pack according to claim 1, characterized in that, The battery cell support is made of metal and has undergone anodizing insulation treatment.

3. The heat dissipation and swelling composite soft-pack battery pack according to claim 1, characterized in that, The battery cell support is made of high-strength plastic filled with inorganic thermally conductive filler; The high-strength plastic is selected from one of polyetheretherketone, polycarbonate, polyphenylene sulfide, polyamide, and glass fiber reinforced thermosetting plastics; The inorganic thermally conductive filler is selected from at least one of magnesium oxide, aluminum oxide, aluminum nitride, boron nitride, and silicon carbide.

4. The heat dissipation and swelling composite soft-pack battery pack according to claim 1, characterized in that, The battery cell support includes a top plate and a side plate. The top plate has a tray structure. The side plate is located on one side of the top plate, and a tab slot is provided for the corresponding tab. The tab passes through the tab slot.

5. The heat dissipation and swelling composite soft-pack battery pack according to claim 4, characterized in that, The top plate is also provided with several supporting legs, which abut against the inner wall of the outer shell.

6. The heat dissipation and swelling-absorbing composite soft-pack battery pack according to claim 5, characterized in that, The aforementioned support legs are provided in pairs, with a notch between the two support legs.

7. The heat dissipation and swelling composite soft-pack battery pack according to claim 4, characterized in that, A thermal pad is provided between the side of the battery cell bracket without a side plate and the outer casing.

8. The heat dissipation and swelling-absorbing composite soft-pack battery pack according to claim 1, characterized in that, In the thickness direction of the pouch cell, thermally conductive buffer composites are provided between the pouch battery pack and the cell support and the outer casing.

9. The heat dissipation and swelling composite soft-pack battery pack according to claim 1, characterized in that, The opening area of ​​the through hole is 36% to 64% of the large surface area of ​​the soft-pack battery cell.

10. The heat dissipation and swelling-absorbing composite soft-pack battery pack according to claim 9, characterized in that, The through hole is a single hole located in the center of the thermal pad.

11. The heat dissipation and swelling-absorbing composite soft-pack battery pack according to claim 9, characterized in that, The through hole is a rectangular cross-section hole, and the side length of any side of the rectangular cross-section hole is 3 / 5 to 4 / 5 of the side length of the corresponding soft-pack battery cell.

12. The heat dissipation and swelling-absorbing composite soft-pack battery pack according to claim 1, characterized in that, The thermal pad is a thermally conductive silicone pad, and the elastic buffer is silicone foam or rubber.

13. A power tool, characterized in that, Includes the heat dissipation and swelling composite soft-pack battery pack as described in any one of claims 1 to 12.

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