Battery pack for use with a cordless tool

Abstract

The battery pack for cordless tool comprises an outer shell, a battery pack main body, the battery pack main body comprises a battery cell assembly, the battery cell assembly comprises an inner shell, a battery cell stack and an upper support of battery cell, at least a part of the upper support of battery cell is pressed between the battery cell stack and the inner upper surface of the inner shell, and at least a part of the upper support of battery cell presses the battery cell stack to the bottom wall of the inner shell.The battery pack of the present application solves the problem that the size of the battery pack cannot be standardized by double-layer shell.The battery cell stack is stably connected between the upper part of the support and the inner upper surface of the inner shell.The upper part of the support generates downward pressure on the battery cell stack, thereby pressing the battery cell stack to the bottom wall of the inner shell, so that the battery cell stack is stably connected with the inner bottom surface of the inner shell.The present application not only realizes the standardization of the shape of the soft shell battery cell battery pack, but also ensures that the battery cell assembly can be stably connected with the shell in the stacking direction.

Description

Technical Field

[0001] This invention relates to the field of battery packs, and more specifically, to a battery pack for use in cordless tools. Background Technology

[0002] Driven by the demand for portability, cordless power tools have become a development trend, and battery pack technology is one of the key factors in their development. Currently, cordless power tool battery packs mostly use cylindrical lithium-ion cells (such as 18650 and 21700 models) in hard-shell cells. This is because the dimensions of these hard-shell cells are standardized. Using a specific model of these cells (such as 18650), they can be arbitrarily combined in series or parallel to form standardized series of battery packs (such as 5S1P and 5S2P in an 18V voltage platform or 10S1P, 10S2P, and 10S3P in a 36V voltage platform), providing these packs to cordless power tools with corresponding voltage platforms. This improves the versatility of battery packs and the standardization of cordless power tools, as disclosed by TTI in patent US8450971B.

[0003] Because the aforementioned cylindrical lithium-ion cells typically use rigid metal as their casing, each cell is relatively heavy for the same energy (ampere-hours, Ah). The resulting battery pack is quite heavy, requiring users to overcome significant gravity to operate cordless power tools, thus negatively impacting the user experience.

[0004] Compared to the aforementioned hard-shell cells, a sheet-like soft-shell cell technology (such as lithium polymer cells and solid-state batteries) is also being developed in related fields. Because this type of cell uses a "soft" shell such as aluminum-plastic film to wrap the internal cell body, it is lighter than the aforementioned hard-shell cells under the same energy (ampere-hour, AH) conditions. The battery pack composed of this type of cell is lighter overall, which is beneficial for users to carry and use.

[0005] While soft-shell cells offer advantages over hard-shell cells, such as lighter weight, they also present several drawbacks in battery pack assembly. For instance, their non-standardized dimensions (allowing for customization) are a major factor hindering battery pack standardization, platformization, and generalization. Sheet-shaped soft-shell cells are hexahedral in shape, and their dimensions can be customized to meet capacity (ampere-hours, Ah) and volume requirements (e.g., ...). Figure 11(a, b, c in the text). Due to its manufacturing process, the dimensions of individual cells (e.g., 80*60*6mm) under the same specifications vary significantly (80±2, 60±2, 6±0.3mm). Compared to the standardized dimensions of cylindrical hard-shell cells (φ18±0.3, 65±0.3), the following problems exist when assembling sheet-like soft-shell cells: When assembling sheet-like soft-shell cells, individual cells are generally designed according to the total battery pack capacity (e.g., 2.5A or 5Ah), and then stacked in series using the smallest dimension (e.g., 6±0.3mm as mentioned above). Due to the large dimensional tolerance (±0.3mm) in the thickness direction (6±0.3), the cumulative thickness difference of the cell assembly is large after multiple cells are stacked (30±1.5mm for 5S1P as an example). This 1.5mm thickness difference makes it difficult to standardize the battery pack thickness dimensions, and the design and production of sheet-like soft-pack assembly shells are difficult to standardize.

[0006] On the other hand, due to the large cumulative difference in the dimensions of the battery cell assembly in the thickness direction, the battery cell assembly cannot form a stable connection with the casing in the thickness direction.

[0007] Therefore, how to standardize the shape of soft-shell battery packs while ensuring that the cell components can form a stable connection with the casing in the stacking direction is a key problem that needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to standardize the shape of the soft-shell battery pack while ensuring that the cell assembly can form a stable connection with the shell in the stacking direction.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A battery pack for cordless tools includes an outer shell and a battery pack body disposed within the outer shell. The battery pack body includes a cell assembly, which comprises an inner shell, a cell stack disposed within the inner shell, and a cell support member. Multiple cells are stacked along the direction of their minimum dimension to form the cell stack. The inner shell is fixedly connected to the outer shell. The cell support member is an elastic member, at least a portion of which is pressed between the cell stack and the inner surface of the inner shell, and at least a portion of the cell support member presses the cell stack against the bottom wall of the inner shell.

[0011] Preferably, the front end face of the battery cell is provided with a tab, and along the stacking direction of the battery cell stack, the front wall of the inner shell is provided with a plurality of tab openings, each tab opening allowing a tab on one of the battery cells to pass through;

[0012] The battery pack body also includes a cell connection plate, which is disposed on the outer surface of the front wall of the inner shell, and the tab opening extends through the cell connection plate along the thickness direction of the front wall of the inner shell.

[0013] Preferably, along the stacking direction of the battery cell stack, the dimensions of the plurality of tab openings increase sequentially in the stacking direction of the battery cell stack.

[0014] Preferably, along the stacking direction of the battery cell stack, the size of the uppermost tab opening in the stacking direction of the battery cell stack is larger than the size of the remaining tab openings in the stacking direction of the battery cell stack, and among the remaining tab openings, the size of the lower tab opening in the stacking direction of the battery cell stack is less than or equal to the size of the upper tab opening in the stacking direction of the battery cell stack.

[0015] Preferably, the inner shell includes a plurality of bottom elastic elements, which are arranged at intervals. At least a portion of the support member on the battery cell presses the battery cell stack against the bottom elastic elements. The battery cell stack forms a first bulge space between itself and the inner bottom surface of the outer shell through the gaps between the bottom elastic elements. The bottom elastic elements extend from the front wall or rear wall of the inner shell to the center of the bottom of the inner shell and are cantilevered structures.

[0016] Preferably, there are multiple support members on the battery cell, and the multiple support members on the battery cell are arranged at intervals. The battery cell stack forms a second bulge space between itself and the inner surface of the inner shell through the gaps between the support members on the battery cell.

[0017] Preferably, the support member on the battery cell includes an upper support member and a side support member. The upper support member is pressed between the battery cell stack and the inner surface of the inner shell, and the side support member is pressed between the battery cell stack and the inner surface of the inner shell.

[0018] Preferably, the cell assembly further includes a rear cell support member, which is pressed between the cell stack and the inner rear surface of the inner shell.

[0019] Preferably, the rear wall of the inner shell is provided with a plurality of heat dissipation holes, which are symmetrically distributed on the left and right sides of the rear wall of the inner shell.

[0020] Preferably, the battery cell assembly further includes a thermally conductive flexible body. Along the stacking direction of the battery cell stack, the battery cells and the thermally conductive flexible body are alternately arranged, with the thermally conductive flexible body disposed below the bottommost battery cell.

[0021] Preferably, the inner shell includes a front shell and a rear shell that are interlocked with each other, and the outer shell includes an upper shell and a lower shell that are interlocked with each other.

[0022] In this invention, the battery cell stack is confined within an inner shell, which is then inserted into an outer shell. Even if the dimensional tolerances of the battery cell stack cause deviations in the outer shell's dimensions, the outer shell's external dimensions remain constant. The internal cavity dimensions of the outer shell are slightly larger than the outer dimensions of the inner shell. After inserting the inner shell into the outer shell, a battery pack with uniform dimensions is formed. Therefore, this invention solves the problem of non-standardized battery pack dimensions through a double-shell design. The upper part of the support member is pressed between the battery cell stack and the inner top surface of the inner shell, thus forming a stable connection between the battery cell stack and the inner top surface of the inner shell through the upper part of the support member. According to the principle of action and reaction, the upper part of the support member exerts downward pressure on the battery cell stack, thereby pressing the battery cell stack against the bottom wall of the inner shell, thus forming a stable connection between the battery cell stack and the inner bottom surface of the inner shell. Therefore, the battery cell stack forms a stable connection with the inner shell in the stacking direction. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 A perspective view of a battery pack 10a provided in a specific embodiment of the present invention;

[0025] Figure 2 An exploded view of a battery pack 10a provided in a specific embodiment of the present invention;

[0026] Figure 3 An exploded view of the battery pack body 6 provided in a specific embodiment of the present invention;

[0027] Figure 4 This is a partially exploded view of the battery pack body 6 provided in a specific embodiment of the present invention;

[0028] Figure 5 A perspective view of the battery pack body 6 provided in a specific embodiment of the present invention;

[0029] Figure 6 This is a top view of the battery pack body 6 provided in a specific embodiment of the present invention;

[0030] Figure 7 for Figure 6 Sectional view along line A;

[0031] Figure 8for Figure 7 Enlarged view of part of D;

[0032] Figure 9 for Figure 6 Sectional view along line B;

[0033] Figure 10 This is a schematic diagram of the opening of the cell connection plate according to a specific embodiment of the present invention;

[0034] Figure 11 This is a three-dimensional view of a battery cell provided for a specific embodiment of the present invention.

[0035] Among them, 10a-battery pack, 2-upper shell, 21-locking component, 211-spring support, 3-lower shell, 31-shell spring support, 4-electric control board assembly, 41-power terminal, 42-electric control board positive interface, 43-electric control board negative interface, 44-temperature sensor probe, 45-cell connection board, 451-tab opening, 452-tab opening, 453-tab opening, 454-tab opening, 455-tab opening, 456-connecting piece, 46-rib cable, 47-operation board, 48-electric control main board, 5-cell assembly, 51-front shell, 511-inner upper surface of front shell, 512-inner side of front shell, 513-inner front surface of front shell, 514-bottom elastic element of front shell, 515-tab opening, 516-tab opening, 517-pole 518 - Tab opening, 519 - Tab opening, 52 - Rear housing, 521 - Inner upper part of rear housing, 522 - Inner side of rear housing, 523 - Inner rear part of rear housing, 524 - Bottom elastic element of rear housing, 525 - Heat dissipation hole, 53 - Upper support of battery cell, 531 - Upper part of support, 532 - Side part of support, 54 - Rear support of battery cell, 55 - Battery cell, 551 - Positive tab, 552 - Negative tab, 56 - Thermally conductive flexible body, 57 - Battery cell tab welding part, 58 - Positive electrode of battery cell assembly, 581 - Welding part, 582 - Conductive part, 583 - Connecting part of electronic control motherboard, 59 - Negative electrode of battery cell assembly, 591 - Welding part, 592 - Conductive part, 593 - Connecting part of electronic control motherboard, 6 - Battery pack body, 7 - Second bulge space, 8 - First bulge space. Detailed Implementation

[0036] The core of this invention lies in providing a battery pack for cordless tools, which standardizes the shape of the soft-shell cell battery pack while ensuring that the cell assembly can form a stable connection with the shell in the stacking direction.

[0037] 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 skilled in the art without creative effort are within the scope of protection of this application.

[0038] It should be noted in the embodiments of the present invention that, in the description of the present invention, the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", "middle", etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0039] In this invention, the voltage of the battery pack 10a is typically 10.8V, 18V, 36V, 48V, 56V, or 80V, etc., and there are no limitations on this. The capacity of the battery pack 10a is greater than or equal to 1.5Ah. Cordless power tools can be handheld power tools (such as electric drills, hammer drills, circular saws, sanders, angle grinders, etc.), gardening power tools (such as hair dryers, lawnmowers, lawn trimmers, pruning shears, etc.), or benchtop power tools (such as bench drills, benchtop band saws, benchtop circular saws, etc.).

[0040] The battery pack 10a used in the cordless tool of this invention mainly includes an outer shell and a battery pack body 6 disposed within the outer shell. The battery pack body 6 includes a cell assembly 5 and an electronic control board assembly 4. The cell assembly 5 includes an inner shell, a cell stack disposed within the inner shell, and a cell support member 53.

[0041] Please refer to the attached document. Figure 1 and attached Figure 2 The outer casing specifically includes an upper casing 2 and a lower casing 3. When the upper casing 2 and lower casing 3 are fastened together, they enclose the battery pack body 6. Please refer to the attached document. Figure 3 Appendix Figure 4 Appendix Figure 5 The inner shell specifically includes a front shell 51 and a rear shell 52, which, when fastened together, enclose the cell stack and the cell support member 53. The inner shell and outer shell are fixedly connected. The control board assembly 4 is disposed between the inner shell and the outer shell. The control board assembly 4 includes a main control board 48 and a cell connection plate 45. The main control board 48 is disposed on the upper surface of the inner shell, and the cell connection plate 45 is disposed on the front surface of the inner shell. At least a portion of the cell support member 53 is pressed between the cell stack and the inner upper surface of the inner shell.

[0042] The battery cell stack is formed by stacking multiple battery cells 55. The battery cell 55 is generally sheet-like; please refer to the attached diagram. Figure 11 , attached Figure 11 The battery cell 55 is hexahedral. Generally, the length dimension 'a' of the battery cell 55 is greater than its width dimension 'b', and the width dimension 'b' is greater than its thickness dimension 'c', i.e., a > b > c. When stacking the battery cells 55, they are stacked along the direction of their smallest dimension (direction c), which is also the thickness direction. The battery cell 55 can also be bent into an arc shape around its length or width axis. For example, attaching... Figure 11 The sheet-like battery cell is bent about an axis in direction a, or about an axis in direction b. It is understood that this application is not limited to the disclosed embodiments, and there are no limitations on the structure of the battery cell herein.

[0043] The internal resistance of cell 55 is less than or equal to 8mΩ. Optionally, the internal resistance of cell 55 is less than or equal to 5mΩ. Optionally, the internal resistance of cell 55 is less than or equal to 3mΩ. The discharge current of cell 55 is greater than or equal to 50A. Optionally, the discharge current of cell 55 is greater than or equal to 60A. Optionally, the discharge current of cell 55 is greater than or equal to 80A. The internal resistance of battery pack 10A is less than or equal to 80mΩ. Optionally, the internal resistance of battery pack 10A is less than or equal to 50mΩ. Optionally, the internal resistance of battery pack 10A is less than or equal to 35mΩ. The discharge current of battery pack 10A is greater than or equal to 20A. Optionally, the discharge current of battery pack 10A is greater than or equal to 40A. Optionally, the discharge current of battery pack 10A is greater than or equal to 50A.

[0044] This invention confines the battery cell stack within an inner shell, which is then inserted into an outer shell. Even if dimensional tolerances in the battery cell stack cause deviations in the outer shell's dimensions, the outer shell's external dimensions remain constant. The internal cavity dimensions of the outer shell are slightly larger than the external dimensions of the inner shell. After inserting the inner shell into the outer shell, a battery pack with uniform dimensions is formed. Therefore, this invention solves the problem of non-standardized battery pack dimensions through a double-shell design.

[0045] Please refer to the attached document. Figure 3 and attached Figure 7 The support member 53 on the battery cell specifically includes an upper support member 531 and a side support member 532. The upper support member 531 is pressed between the battery cell stack and the inner top surface of the inner shell, thus forming a stable connection between the battery cell stack and the inner top surface of the inner shell through the upper support member 531. According to the principle of action and reaction, the upper support member 531 exerts downward pressure on the battery cell stack, thereby pressing the battery cell stack against the bottom wall of the inner shell, thus forming a stable connection between the battery cell stack and the inner bottom surface of the inner shell. Therefore, the battery cell stack forms a stable connection with the inner shell in the stacking direction.

[0046] When assembling the battery cell assembly 5, the upper support member 53 of the battery cell is first compressed, so that the bottom of the battery cell stack avoids the bottom wall of the inner shell, allowing it to smoothly enter the front shell 51 or the rear shell 52. After the battery cell stack enters the front shell 51 or the rear shell 52, the upper support member 53 of the battery cell partially springs back, pressing the battery cell stack against the bottom wall of the inner shell, thereby forming a stable connection with the bottom wall of the inner shell.

[0047] The outer casing of the battery cell is a soft shell. When assembling the cells, the design is generally based on the total capacity of the battery pack, and then they are assembled in series using a minimum size orientation (e.g., the 6mm orientation in an 80*60*6mm cell). Each cell 55 has tabs, typically including a positive tab 551 and a negative tab 552. In multiple cells 55, the negative tab 552 of the Nth cell 55 is connected to the positive tab 551 of the (N+1)th cell. The positive tab 551 of the first cell 55 is the overall positive electrode of the cell stack, and the negative tab 552 of the last cell 55 is the overall negative electrode of the cell stack. In some embodiments, please refer to the appendix. Figure 3 The negative tab 552 of the first cell 55e is connected to the positive tab 551 of the second cell 55d, and so on, connecting the five cells 55e-55a in series. Ultimately, the positive tab 551 of 55e serves as the overall positive electrode of the cell stack, and the negative tab 552 of 55a serves as the overall negative electrode. Those skilled in the art know that this type of cell assembly is 5S1P. In other embodiments, the positive tab 551 of 55e can be soldered to the cell stack, changing the 5S1P configuration to have the negative tab 552 of 55e serve as the overall negative electrode of the cell stack, and the positive tab 551 of 55a serve as the overall positive electrode. In short, when the cells are connected in series, the positive and negative tabs of the first and last cells can both serve as the overall positive and negative electrodes of the cell stack.

[0048] In this embodiment, the positive and negative tabs (551, 552) are disposed on one side of the battery cell 55, that is, extending cantilevered from one side of the battery cell 55 along the length of the battery cell 55. In some embodiments, the positive tab 551 and the negative tab 552 are located on the rear end face of the battery cell 55. In other embodiments, the positive tab 551 and the negative tab 552 are located on the front and rear end faces of the battery cell 55, respectively. (Refer to the attached diagram.) Figure 3 , attached Figure 3 The positive electrode tab 551 and the negative electrode tab 552 are located on the front end face of the cell 55.

[0049] Along the stacking direction of the battery cells, the front wall of the inner shell has multiple tab openings, each allowing a tab of one battery cell 55 to pass through. The front end face of the battery cell 55 has a positive tab 551 and a negative tab 552. Correspondingly, the front wall of the inner shell has two rows of tab openings. The two tab openings in each row allow the positive tab 551 and negative tab 552 of one battery cell 55 to pass through, respectively. The battery cell connecting plate 45 of the control board assembly 4 is disposed on the front surface of the front shell 51. The shape and size of the battery cell connecting plate 45 are approximately the same as the front surface of the front shell. Tab openings corresponding to the tab openings on the front wall of the inner shell are formed on the battery cell connecting plate 45.

[0050] Please refer to the attached document. Figure 3 and attached Figure 4 In the appendix Figure 3 On the front wall of the inner shell, tab openings 515, 516, 517, 518, and 519 are sequentially formed along the stacking direction of the cell assembly, with each tab opening consisting of two symmetrically arranged tab openings. (See attached...) Figure 4 The cell connection plate 45 has tab openings 451, 452, 453, 454, and 455 sequentially formed along the stacking direction of the cell stack, with each tab opening consisting of two symmetrically arranged tabs. The cell connection plate 45 is also provided with connecting pieces 456 for welding the positive tab 551 and the negative tab 552.

[0051] When stacked in series from bottom to top, the negative tab 552 of cell 55a passes through the tab openings 515 and 451 on the right side, and the positive tab 551 passes through the tab openings 515 and 451 on the left side. The positive tab 551 of cell 55b passes through the tab openings 516 and 452 on the right side, and the negative tab 552 passes through the tab openings 516 and 452 on the left side. The negative tab 552 of cell 55c passes through the tab openings 517 and 453 on the right side, and the positive tab 551 passes through the tab openings 517 and 453 on the left side. The positive tab 551 of cell 55d passes through the tab openings 518 and 454 on the right side, and the negative tab 552 passes through the tab openings 518 and 454 on the left side. The negative tab 552 on cell 55e passes through the tab opening 519 and tab opening 455 on the right side, and the positive tab 551 passes through the tab opening 519 and tab opening 455 on the left side.

[0052] Please refer to the attached document. Figure 10All tab openings have the same length, or dimension L in the left-right direction as shown in the attached diagram. The cell stack is formed along the direction of the smallest dimension of cell 55, i.e., the thickness direction. However, the dimensional tolerance of cell 55 in the thickness direction is relatively large; for a cell 55 with a thickness of 6mm, the dimensional tolerance is ±0.3mm. After stacking five cells 55, the cumulative thickness of the cell stack varies considerably, with a thickness of 30±1.5mm. Please refer to the attached diagram. Figure 3 and attached Figure 11 When battery cells 55 are stacked sequentially in the order of 55a-55e, and the thickness dimension c of battery cell 55 has a tolerance of ±0.3mm, the tolerance between the later-stacked battery cells 55 increases. For example, the tolerance between 55e and 55d is ±0.3*5mm, and the tolerance between 55d and 55c is ±0.3*4mm. To facilitate the smooth passage of the positive and negative tabs of battery cell 55 through the corresponding tab openings, this invention designs the height dimension of the tab opening, or the dimension of the tab opening in the stacking direction, as follows: along the stacking direction of the battery cell stack, the height dimension of the tab opening gradually increases to compensate for the gradually increasing thickness dimension tolerance of the battery cell 55. Please refer to the appendix. Figure 10 In the appendix Figure 10 The height dimension of the middle tab opening 451 is H1, the height dimension of the tab opening 452 is H2, the height dimension of the tab opening 453 is H3, the height dimension of the tab opening 454 is H4, and the height dimension of the tab opening 455 is H5. Then H1 < H2 < H3 < H4 < H5, or H1 ≤ H2 ≤ H3 ≤ H4 < H5.

[0053] Multiple bottom elastic members are formed at the bottom of the inner shell, and the multiple bottom elastic members are arranged at intervals. The upper part 531 of the support member presses the battery cell stack against the bottom elastic members. The bottom elastic members have a certain thickness, so the battery cell stack forms a first bulge space 8 between itself and the inner bottom surface of the outer shell through the gaps between the bottom elastic members.

[0054] Please refer to the attached document. Figure 5 In a specific embodiment of the present invention, the bottom elastic element specifically includes a front shell bottom elastic element 514 and a rear shell bottom elastic element 524. Multiple front shell bottom elastic elements 514 are arranged at intervals along the left-right direction, and multiple rear shell bottom elastic elements 524 are arranged at intervals along the left-right direction, with the front shell bottom elastic elements 514 and rear shell bottom elastic elements 524 spaced apart. Therefore, the first bulge space 8 is distributed between adjacent front shell bottom elastic elements 514, between adjacent rear shell bottom elastic elements 524, and between the front shell bottom elastic elements 514 and rear shell bottom elastic elements 524.

[0055] If cell 55 bulges, it will typically bulge along the direction of its smallest dimension, i.e., the vertical direction shown in the attached figure. In this invention, the cell stack forms a first bulge space 8 between the gap between the bottom elastic members and the inner bottom surface of the outer shell. Therefore, if cell 55 bulges, it will preferentially bulge downwards and towards the first bulge space 8. Since the first bulge space 8 is reserved in the bulge direction, it facilitates the bulging of cell 55, thereby preventing cell 55 from exploding. On the other hand, in the bulge direction, i.e., the vertical direction, the cell stack is pressed against the inner top surface of the inner shell (the inner top surface 511 of the front shell 51 and the inner top surface 521 of the rear shell 52) by the upper part 531 of the support member. The upper part 531 of the support member presses the cell stack against the bottom elastic member, thus the cell stack is pressed against the inner bottom surface of the inner shell. In this way, the cell stack is tightly connected to the inner shell in the vertical direction, i.e., the bulge direction. Therefore, this invention both facilitates cell bulging and ensures the stability of the connection between the cell stack and the inner shell.

[0056] The bottom elastic element extends from the front or rear wall of the inner shell towards the bottom center of the inner shell, and the bottom elastic element has a cantilever structure. Please refer to the appendix. Figure 5 The front shell bottom elastic member 514 extends rearward from the front wall of the front shell 51, forming a rearward cantilever structure relative to the front wall of the front shell 51. The rear shell bottom elastic member 524 extends forward from the rear wall of the rear shell 52, forming a forward cantilever structure relative to the rear wall of the rear shell 52. The end of the front shell bottom elastic member 514 near the center of the bottom of the inner shell can deform to a greater extent than the end farther from the center of the bottom of the inner shell. Similarly, the end of the rear shell bottom elastic member 524 near the center of the bottom of the inner shell can deform to a greater extent than the end farther from the center of the bottom of the inner shell. The bulge of the battery cell 55 is usually located at the center of the battery cell 55, that is, the center of the bottom of the inner shell. Since the bottom elastic element 514 of the front shell and the bottom elastic element 524 of the rear shell can deform to a large extent at the bottom center of the inner shell, the cantilevered bottom elastic element 514 of the front shell and the bottom elastic element 524 of the rear shell deform accordingly when the cell 55 bulges, which facilitates the downward bulging of the cell 55.

[0057] Please refer to the attached document. Figure 3 Appendix Figure 7 Appendix Figure 8There are multiple support members 53 on the battery cell, which are arranged at intervals. The battery cell stack forms a second bulge space 7 between the inner upper surface 511 of the front housing and the inner upper surface 521 of the rear housing through the gaps between the upper support members 53. More specifically, the battery cell stack forms a second bulge space 7 between the inner upper surface 511 of the front housing 51 and the inner upper surface 521 of the rear housing 52 through the gaps between the upper parts 531 of the support members. In this way, the battery cell 55 can also bulge into the second bulge space 7, which further facilitates the bulging of the battery cell 55.

[0058] The support side 532 of the support member 53 on the battery cell is pressed between the inner side of the battery cell stack and the inner side of the inner shell (the inner side 512 of the front shell 51 and the inner side 522 of the rear shell 52). The battery cell stack is reliably connected to the inner side of the inner shell through the support side 532, thereby further improving the stability of the connection between the battery cell stack and the inner shell.

[0059] The support member 53 on the battery cell is an elastomer with a supporting function. The compression ratio of the support member 53 on the battery cell is greater than or equal to 30%. Optionally, the compression ratio of the support member 53 on the battery cell is greater than or equal to 50%. For example, the support member 53 on the battery cell can be a polyurethane foam or a polyether foam.

[0060] Please refer to the attached document. Figure 3 Appendix Figure 4 Appendix Figure 8 The battery cell assembly 5 of this invention further includes a rear support member 54, which is pressed between the battery cell stack and the inner rear surface 523 of the inner shell (rear shell 52). The battery cell stack is tightly connected to the rear wall of the inner shell through the rear support member 54. The rear support member 54 is an elastic body with a supporting function, and the compression ratio of the rear support member 54 is greater than or equal to 30%. Optionally, the compression ratio of the rear support member 54 is greater than or equal to 50%. For example, the rear support member 54 can be a polyurethane foam or a polyether foam.

[0061] The rear support member 54 of the battery cell can also be an insulator with thermal conductivity. The thermal conductivity of the rear support member 54 can be greater than or equal to 1.0 W / (mK), optionally greater than or equal to 1.5 W / (mK), or optionally greater than or equal to 1.8 W / (mK). The compression ratio of the rear support member 54 is greater than or equal to 10%, optionally greater than or equal to 20%. The elongation at break of the rear support member 54 is greater than or equal to 50%, optionally greater than or equal to 100%. The thermal conductivity unit W / (mK) mentioned above refers to the amount of heat transferred through a 1 square meter area in 1 second (1 s) under steady heat transfer conditions, with a temperature difference of 1 degree (K, ℃) between the two surfaces of a 1 m thick material. The unit is watts per meter·degree (W / (m·K)), where K can be replaced by ℃.

[0062] Please refer to the attached document. Figure 4 and attached Figure 5 To facilitate heat dissipation of the battery cell stack, the present invention provides multiple heat dissipation holes 525 on the rear wall of the inner shell, or the rear wall of the rear shell 52. Furthermore, the multiple heat dissipation holes 525 are divided into two rows, symmetrically distributed on the left and right sides of the rear wall of the inner shell. This arrangement achieves heat dissipation while ensuring the support effect of the rear wall of the rear shell 52 on the rear support member 54 of the battery cell, thus improving the stability of the connection between the battery cell stack and the inner shell. Each heat dissipation hole 525 in each row corresponds to one battery cell 55, allowing the user to observe the rear surface of the internal battery cell 55 through the heat dissipation holes 525 when viewed from back to front.

[0063] Please refer to the attached document. Figure 3 In a specific embodiment of the present invention, the battery cell assembly 5 further includes a thermally conductive flexible body 56. Along the stacking direction of the battery cell stack, the battery cell 55 and the thermally conductive flexible body 56 are alternately arranged. The thermally conductive flexible body 56 is an insulator with thermal conductivity, thereby facilitating heat dissipation from the battery cell 55. The thermal conductivity of the thermally conductive flexible body 56 can be greater than or equal to 1.0 W / (mK). Optionally, the thermal conductivity of the thermally conductive flexible body 56 is greater than or equal to 1.5 W / (mK), and optionally, the thermal conductivity of the thermally conductive flexible body 56 is greater than or equal to 1.8 W / (mK). The aforementioned thermal conductivity unit W / (mK) refers to the amount of heat transferred through a 1 square meter area in 1 second (1 s) under stable heat transfer conditions, with a temperature difference of 1 degree (K, ℃) between the two surfaces of a 1 m thick material. The unit is watts per meter·degree (W / (m·K)), where K can be replaced by ℃.

[0064] The compression ratio of the thermally conductive flexible body 56 is greater than or equal to 10%. Optionally, the compression ratio of the thermally conductive flexible body 56 is greater than or equal to 20%. Since the compression ratio of the thermally conductive flexible body 56 is greater than or equal to 10%, this setting has the advantage of effectively fitting the outer surface of the battery cell 55, reducing the air gap between the battery cell 55 and the thermally conductive flexible body 56 caused by the flatness difference of the battery cell 55, and increasing the thermally conductive bonding area.

[0065] In one specific embodiment of the present invention, a thermally conductive flexible body 56 is disposed below the bottommost battery cell 55. This arrangement serves two purposes: firstly, the bottommost thermally conductive flexible body 56 conducts heat from the battery cell stack to the outside; secondly, when the battery cell stack bulges downwards, the thermally conductive flexible body 56 provides a flexible constraint on the bulging area, thereby guiding the bulging of the battery cell stack flexibly and preventing breakage due to stress concentration during bulging. The elongation at break of the thermally conductive flexible body 56 is greater than or equal to 50%. Optionally, the elongation at break of the thermally conductive flexible body 56 is greater than or equal to 100%, thus ensuring that the thermally conductive flexible body 56 provides effective flexible constraint on the bulging area of ​​the battery cell stack.

[0066] The battery pack 10a is detachably connected to the cordless power tool via locking element 21. Please refer to the attached document. Figure 2 The locking member 21 is provided with a spring support portion 211 for supporting the spring 22 in the vertical direction. The lower end of the spring 22 is supported by the spring support portion 31 provided on the lower housing 3. The spring 22 is disposed between the locking member 21 and the lower housing 3 in the vertical direction. Since the locking member 21 is limited to moving only in the vertical direction by the spring support portion 211 and the spring support portion 31, the spring 22 can only be compressed by the locking member 21 in a generally vertical direction. In the integrated state of the battery pack 10a... Figure 1 The spring 22 always maintains a force that presses the locking member 21 upward, meaning that the locking member 21 can be pressed downward by the user. When the user releases the downward pressure, the locking member 21 will move upward under the action of the spring 22, returning to its original position. Figure 1 state.

[0067] As described above, the electronic control board assembly 4 includes a cell connection board 45 and an electronic control main board 48. The cell connection board 45 is disposed on the front surface of the front housing 51, and the electronic control main board 48 is disposed on the upper surfaces of the front housing 51 and the rear housing 52.

[0068] Please refer to the attached document. Figure 3The main control board 48 is equipped with a power terminal 41 for electrical connection to the cordless power tool, a positive control board interface 42 soldered to the positive terminal 58 of the battery cell assembly, a negative control board interface 43 soldered to the negative terminal 59 of the battery cell assembly, and a temperature sensor probe 44 for monitoring the operating temperature of the battery cell assembly 5. The temperature sensor probe 44 is a thermistor, such as an NTC or PTC. It is understood that the charge / discharge management unit (MCU) of the battery cell assembly 5 is also located on the main control board 48, and the operation board 47 is electrically connected to the main control board 48 via a ribbon cable 46. The operation board 47 is located on the rear surface of the inner shell. When the user operates the operation board 47, the display unit on the operation board 47 will provide status information of the battery cell assembly 5. Some embodiments of the display unit are multiple independent LEDs used to display the battery level or fault information of the battery cell assembly 5; other embodiments are LED display screens that display the battery level or fault information of the battery cell assembly 5 through icons or characters. The soldering described above can be any of the soldering processes such as tin soldering, resistance soldering, and laser soldering.

[0069] Regarding the connection method between the inner shell and the outer shell: In a specific embodiment of the present invention, a potting compound layer is sealed between the outer front surface of the inner shell and the inner front surface of the outer shell, and the potting compound layer connects the inner front surface of the outer shell and the outer front surface of the front shell. That is, the inner shell and the outer shell are connected by the potting compound layer.

[0070] The inner shell communicates with the outer shell sequentially through the tab openings on the front wall of the front shell 51 and the tab openings on the cell connecting plate 45. During the potting process, the potting compound enters the inner shell and reaches the cell stack sequentially through the tab openings on the cell connecting plate 45 and the front shell 51. After curing, a connecting adhesive portion is formed. The cell stack is then connected to the outer shell sequentially through the connecting adhesive portion and the potting compound layer.

[0071] In this invention, the inner shell and the outer shell are connected by a potting compound layer, and the battery cell stack is connected to the outer shell by a connecting glue part and a potting compound layer. In this way, the stability of the connection between the inner shell and the battery cell stack and the outer shell is ensured.

[0072] Finally, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0073] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery pack for cordless tools, comprising a housing and a battery pack body (6) disposed within the housing, characterized in that, The battery pack body (6) includes a cell assembly (5), which includes an inner shell, a cell stack disposed in the inner shell, and a cell support member (53). Multiple cells (55) are stacked along the smallest dimension direction of the cells (55) to form the cell stack. The inner shell is fixedly connected to the outer shell. The cell support member (53) is an elastic member. At least a portion of the cell support member (53) is pressed between the cell stack and the inner top surface of the inner shell, and at least a portion of the cell support member (53) presses the cell stack against the bottom wall of the inner shell. The front end face of the battery cell (55) is provided with a tab. Along the stacking direction of the battery cell stack, the front wall of the inner shell is provided with a plurality of tab openings, each tab opening allowing a tab on the battery cell (55) to pass through. The battery pack body (6) also includes a battery cell connecting plate (45), which is disposed on the outer surface of the front wall of the inner shell. The tab openings pass through the battery cell connecting plate (45) along the thickness direction of the front wall of the inner shell. Along the stacking direction of the battery cell stack, the size of the plurality of electrode openings increases sequentially in the stacking direction of the battery cell stack; Along the stacking direction of the battery cell stack, the size of the uppermost tab opening in the stacking direction of the battery cell stack is larger than the size of the remaining tab openings in the stacking direction of the battery cell stack, and among the remaining tab openings, the size of the lower tab opening in the stacking direction of the battery cell stack is less than or equal to the size of the upper tab opening in the stacking direction of the battery cell stack.

2. The battery pack for cordless tools according to claim 1, characterized in that, The inner shell includes a bottom elastic member, and there are multiple bottom elastic members arranged at intervals. At least a portion of the upper support member (53) of the battery cell presses the battery cell stack against the bottom elastic member. The battery cell stack forms a first bulge space (8) between itself and the inner bottom surface of the outer shell through the gap between the bottom elastic members. The bottom elastic member extends from the front wall or rear wall of the inner shell to the center of the bottom of the inner shell and is a cantilever structure.

3. The battery pack for cordless tools according to claim 1, characterized in that, There are multiple support members (53) on the battery cell, and the multiple support members (53) on the battery cell are arranged at intervals. The battery cell stack forms a second bulge space (7) between the battery cell support members (53) and the inner surface of the inner shell.

4. The battery pack for cordless tools according to claim 3, characterized in that, The cell support member (53) includes an upper support member (531) and a side support member (532). The upper support member (531) is pressed between the cell stack and the inner surface of the inner shell, and the side support member (532) is pressed between the cell stack and the inner surface of the inner shell.

5. The battery pack for cordless tools according to claim 1, characterized in that, The cell assembly (5) also includes a cell rear support member (54), which is pressed between the cell stack and the inner rear surface of the inner shell.

6. The battery pack for cordless tools according to claim 5, characterized in that, The rear wall of the inner shell is provided with a plurality of heat dissipation holes (525), which are symmetrically distributed on the left and right sides of the rear wall of the inner shell.

7. The battery pack for cordless tools according to claim 1, characterized in that, The battery cell assembly (5) also includes a thermally conductive flexible body (56). Along the stacking direction of the battery cell stack, the battery cell (55) and the thermally conductive flexible body (56) are alternately arranged, and the thermally conductive flexible body (56) is arranged below the bottommost battery cell (55).

8. The battery pack for cordless tools according to claim 1, characterized in that, The inner shell includes a front shell (51) and a rear shell (52) that are interlocked with each other, and the outer shell includes an upper shell (2) and a lower shell (3) that are interlocked with each other.

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