Lower box body and battery pack

Abstract

The embodiment of the invention provides a lower box body and a battery pack, and relates to the technical field of power batteries. The lower box body of the battery pack comprises a box body frame, a bottom plate and a bottom protection plate. The box body frame is a metal frame. The bottom plate is of a laminated structure composed of a plurality of continuous fiber layers, and the fiber laying directions of every two adjacent continuous fiber layers are different. The bottom plate is fixedly connected with the box frame through a plurality of first fasteners. And a sealing glue layer is arranged between the bottom plate and the box body frame. And the bottom protection plate is fixedly connected with the box body frame through a plurality of second fasteners, so that the bottom plate is clamped between the bottom protection plate and the box body frame. The light weight of the lower box body of the battery pack can be realized, meanwhile, the connection strength and the sealing reliability between the composite material bottom plate serving as a main load-bearing structure and the metal frame are ensured, and the overall protection performance of the bottom of the battery pack is improved.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and more specifically, to a lower housing and battery pack. Background Technology

[0002] With the rapid development of the new energy vehicle industry, lightweighting of power battery packs has become crucial for improving vehicle range. The battery pack housing, as a core structural component, is of paramount importance in terms of weight and performance. Currently, mainstream solutions still employ all-aluminum alloy or steel structures, which, while meeting basic strength requirements, result in excessively high housing weight due to the high material density, severely limiting the improvement of system energy density.

[0003] To reduce weight, existing technologies have begun to use composite materials in battery packs. However, the application of composite materials is mostly limited to non-load-bearing components, and their application in major load-bearing structures faces technical bottlenecks such as insufficient connection strength and poor sealing reliability. Summary of the Invention

[0004] The present invention aims to provide a lower housing and a battery pack that can achieve lightweighting of the lower housing of the battery pack, while ensuring the connection strength and sealing reliability between the composite material base plate, which serves as the main load-bearing structure, and the metal frame, and improve the overall protective performance of the bottom of the battery pack.

[0005] The embodiments of the present invention can be implemented as follows: In a first aspect, the present invention provides a lower housing, comprising: Box frame, wherein the box frame is a metal frame; The base plate is a laminated structure composed of multiple continuous fiber layers, and the fiber laying directions of two adjacent continuous fiber layers are different; the base plate is fixedly connected to the box frame by multiple first fasteners; a sealant layer is provided between the base plate and the box frame; The bottom protective plate is fixedly connected to the box frame by a plurality of second fasteners, so that the bottom plate is sandwiched between the bottom protective plate and the box frame.

[0006] In an optional embodiment, the base plate has a thickened structure in the local area where it is connected to the first fastener and / or the second fastener.

[0007] In an optional embodiment, the thickened structure is integrally formed with the base plate and consists of the additionally laid continuous fiber layer.

[0008] In an optional embodiment, the thickened structure is disposed on the side of the base plate facing the bottom guard plate.

[0009] In an optional embodiment, the bottom plate has a groove on the side facing the housing frame, the groove being used to accommodate the protruding structure at the bottom of the battery module.

[0010] In an optional embodiment, the box frame includes an outer frame and a plurality of inner support beams disposed within the outer frame; the inner support beams include transverse support beams and longitudinal support beams, and the transverse support beams and the longitudinal support beams are cross-connected.

[0011] In an optional embodiment, the base plate is fixedly connected to the outer frame via the first fastener; the bottom guard plate is fixedly connected to the outer frame and the inner support beam via the second fastener, wherein at the connection position between the bottom guard plate and the inner support beam, the base plate has a through hole for the second fastener to pass through, so that the base plate is sandwiched between the bottom guard plate and the box frame.

[0012] In an optional embodiment, the box frame is further provided with an overflow groove on the side facing the bottom plate.

[0013] In an optional embodiment, a cavity is provided between the bottom protective plate and the bottom plate, and the cavity is filled with a support member.

[0014] Secondly, the present invention provides a battery pack, including the lower housing as described in any of the foregoing embodiments.

[0015] The beneficial effects of the lower housing and battery pack provided in the embodiments of the present invention include: The lower casing of the battery pack of the present invention includes a casing frame, a bottom plate, and a bottom protective plate. The casing frame is a metal frame. The bottom plate is a laminated structure composed of multiple continuous fiber layers, with adjacent continuous fiber layers having different fiber layup directions. The bottom plate is fixedly connected to the casing frame by multiple first fasteners. A sealant layer is provided between the bottom plate and the casing frame. The bottom protective plate is fixedly connected to the casing frame by multiple second fasteners, so that the bottom plate is sandwiched between the bottom protective plate and the casing frame. By using a continuous fiber laminated structure to replace the traditional metal bottom plate, the high strength and high modulus characteristics of composite materials are fully utilized, significantly reducing the weight of the casing. The cross-layup design with adjacent fiber layers laid in different directions gives the bottom plate excellent tensile and bending strength in all in-plane directions, ensuring its reliability as the main load-bearing structure. Through the composite connection structure of the bottom plate, sealant layer, and casing frame, the sealant not only plays a sealing role but also enhances the connection rigidity between the bottom plate and the metal frame, effectively dispersing stress concentration around the fasteners. The outermost bottom protective plate provides direct physical protection against scratches and gravel impacts to the bottom plate. The lower casing of this invention enables the battery pack to be lightweight, while ensuring the connection strength and sealing reliability between the composite material bottom plate, which serves as the main load-bearing structure, and the metal frame, and improving the overall protective performance of the bottom of the battery pack. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is an exploded structural diagram of the lower housing provided in this embodiment; Figure 2 This is a schematic diagram of the connection structure between the outer frame and the bottom protective plate provided in this embodiment; Figure 3 This is a schematic diagram of the connection structure between the internal support beam and the base plate provided in this embodiment; Figure 4 This is a schematic diagram of the connection structure between the outer frame and the base plate provided in this embodiment; Figure 5 This is a schematic diagram of the groove structure of the base plate provided in this embodiment; Figure 6 This is a partial structural diagram of the battery pack provided in this embodiment.

[0018] Icons: 100-Lower housing; 10-Housing frame; 11-Outer frame; 111-Glue overflow groove; 12-Inner support beam; 121-Longitudinal support beam; 122-Transverse support beam; 20-Bottom plate; 21-Groove; 22-First fastener; 23-Thickened structure; 24-Sealant layer; 30-Bottom protective plate; 31-Second fastener; 32-Cavity; 33-Support component; 34-Sealing gasket; 200-Battery module; 201-Protruding structure. Detailed Implementation

[0019] The all-metal battery pack lower casing in related technologies suffers from issues such as heavy weight, which affects the driving range of electric vehicles; and existing composite material application solutions are difficult to apply effectively to the main load-bearing structures due to insufficient connection strength and poor sealing reliability.

[0020] To address the aforementioned issues, this invention provides a lower housing and battery pack utilizing a composite material base plate. By employing a combination structure of a composite material base plate with continuous fiber cross-layouts and a metal frame, along with a composite connection method using a sealant layer and mechanical fasteners, the lower housing achieves significant weight reduction while ensuring connection strength and sealing reliability. This effectively improves upon the problems of excessive weight in traditional metal lower housings and weak connections and poor sealing in existing composite material application solutions.

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and 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, and therefore should not be construed as a limitation of this invention.

[0025] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0026] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0027] The following describes in detail the overall structure, working principle, and technical effects of the lower housing 100 and battery pack provided by the present invention through embodiments and in conjunction with the accompanying drawings.

[0028] Please refer to Figures 1-4 The lower housing 100 provided by the present invention is applied to the power battery pack of electric vehicles, serving as a core component that carries the battery module 200 and provides structural support and bottom protection.

[0029] The lower enclosure 100 includes an enclosure frame 10, a bottom plate 20, and a bottom protective plate 30. The enclosure frame 10 is a metal frame. The bottom plate 20 is a laminated structure composed of multiple continuous fiber layers, with the fiber laying directions of adjacent connecting fiber layers being different. The bottom plate 20 is fixedly connected to the enclosure frame 10 by a plurality of first fasteners 22. A sealant layer 24 is provided between the bottom plate 20 and the enclosure frame 10. The bottom protective plate 30 is fixedly connected to the enclosure frame 10 by a plurality of second fasteners 31, so that the bottom plate 20 is sandwiched between the bottom protective plate 30 and the enclosure frame 10.

[0030] By using a composite material base plate 20 composed of cross-laid continuous fiber layers as the main load-bearing structure, the weight of the lower enclosure 100 can be significantly reduced while ensuring structural strength. The combination of a sealant layer 24 and mechanical fasteners enhances connection strength and ensures reliable sealing. By sandwiching the base plate 20 between the bottom protective plate 30 and the enclosure frame 10, overall rigidity and impact resistance are improved, effectively solving the technical problems of the traditional heavy metal lower enclosure 100 and the insufficient connection strength and poor sealing reliability of existing composite material applications.

[0031] As can be understood, a continuous fiber layer refers to a composite monolayer composed of uninterrupted fibers (such as carbon fiber or glass fiber) extending continuously in a specific direction within a matrix material (such as epoxy resin). The fibers are arranged in a specific layup direction within the layer, giving the monolayer the highest strength and stiffness in the fiber direction, exhibiting significant anisotropy. Multiple such continuous fiber layers are stacked, laid, and cured in different directions to collectively form the laminated structure of the base plate 20. The cross-layup design with adjacent layers having different fiber directions enhances the overall mechanical properties of the base plate 20 planar surface.

[0032] The continuous fiber layer can be made of different fiber materials as needed. In one embodiment of the invention, the continuous fiber is carbon fiber, which has excellent specific strength and specific modulus, making it an ideal choice for achieving lightweighting. In other embodiments, the continuous fiber can also be one or a combination of the following materials: glass fiber, aramid fiber, and basalt fiber, wherein glass fiber has relatively low cost and excellent insulation properties, aramid fiber has excellent impact resistance and fatigue resistance, and basalt fiber has excellent high-temperature resistance and corrosion resistance.

[0033] Furthermore, the base plate 20 has a thickened structure 23 in the local area where it connects with the first fastener 22 and / or the second fastener 31. By providing the local thickened structure 23, the thickness and effective load-bearing area of ​​the composite material base plate 20 in the fastener connection area can be significantly increased. This reduces the compressive stress and interlaminar shear stress generated at the hole wall of the base plate 20 by the fastener preload and external load, avoids stress concentration, increases the local compressive modulus of the base plate 20, reduces the risk of fastener loosening under vibration load, and ensures the long-term stability of the connection.

[0034] In this embodiment, the base plate 20 is provided with a thickened structure 23 at the positions corresponding to the first fastener 22 and the second fastener 31. In other embodiments, the thickened structure 23 can be adaptively adjusted according to the actual stress conditions and spatial constraints. For example, the base plate 20 may only have the thickened structure 23 at the position corresponding to the first fastener 22, that is, only locally reinforce the connection area between the base plate 20 and the box frame 10; the base plate 20 may only have the thickened structure 23 at the position corresponding to the second fastener 31, that is, reinforce the pressing area of ​​the base plate 20 when the bottom guard plate 30 is connected to the box frame 10.

[0035] Specifically, the thickened structure 23 is integrally formed with the base plate 20 and is composed of additional continuous fiber layers. It can be understood that the integral forming here refers to the process of increasing the number of continuous fiber layers in local areas during the manufacturing of the base plate 20, so that the thickened structure 23 and the main body of the base plate 20 are formed simultaneously in a one-time curing process, thus becoming a complete integral component without additional connecting interfaces.

[0036] For example, in this embodiment, the base plate 20 is composed of six layers of continuous fiber, with a nominal thickness of 0.2 mm for each continuous fiber layer, resulting in a total thickness of 1.2 mm for the main body of the base plate 20. In the local area corresponding to the connection between the first fastener 22 and the second fastener 31, five additional layers of continuous fiber are laid on top of the main layer, thus forming the aforementioned thickened structure 23. Based on this design, the base plate 20 at the thickened structure 23 has a total of eleven layers, corresponding to a total thickness of 2.2 mm, while the number of layers at other locations remains six, with a thickness of 1.2 mm.

[0037] In this embodiment, the fiber laying direction of the main body of the base plate 20, perpendicular to the plane of the base plate 20, is 0° / 90° / 0° / 90° / 0° / 90°. The lay-up sequence of the additional five continuous fiber layers is 0° / 90° / 0° / 90° / 0°. It can be understood that in this embodiment, the fiber laying directions of two adjacent continuous fiber layers are perpendicular.

[0038] Furthermore, the thickened structure 23 is located on the side of the base plate 20 facing the bottom protective plate 30. Understandably, this arrangement keeps the side of the base plate 20 facing the interior of the housing frame 10 flat and smooth, avoiding the occupation of battery module 200 arrangement space due to internal protrusions, and also eliminating possible interference with module installation, ensuring maximum utilization of the internal space of the battery pack and ease of assembly.

[0039] Specifically, the box frame 10 includes an outer frame 11 and a plurality of inner support beams 12 disposed within the outer frame 11. The inner support beams 12 include transverse support beams 122 and longitudinal support beams 121. The transverse support beams 122 and longitudinal support beams 121 are cross-connected.

[0040] By setting up a cross-connected inner support beam 12 structure, the base plate 20 can be divided into multiple smaller continuous support areas, thereby shortening the actual stress span of the base plate 20, decomposing and transferring the large-area distributed load to multiple inner support beams 12, significantly reducing the bending deformation of the base plate 20 under load; it can also transfer the weight of the battery module 200, the inertial force during driving, and the impact load to the outer frame 11, avoiding excessive stress concentration in the local area of ​​the base plate 20.

[0041] Furthermore, the base plate 20 is fixedly connected to the outer frame 11 by a first fastener 22. The bottom guard plate 30 is fixedly connected to the outer frame 11 and the inner support beam 12 by a second fastener 31. At the connection point between the bottom guard plate 30 and the inner support beam 12, a through hole is provided on the base plate 20 for the second fastener 31 to pass through, so that the base plate 20 is sandwiched between the bottom guard plate 30 and the box frame 10. By using a structure where the second fastener 31 is shared at the inner support beam 12 to connect the bottom guard plate 30 and the box frame 10 and passes through the base plate 20, the fixation of the bottom guard plate 30 and the constraint of the base plate 20 at the position of the inner support beam 12 can be achieved. Additional clamping force is applied to the base plate 20 at the inner support beam 12, effectively suppressing the vibration and warping deformation of the base plate 20 under complex loads and improving the uniformity of the overall structural stiffness.

[0042] Furthermore, an overflow groove 111 is provided on the side of the housing frame 10 facing the bottom plate 20. It is understood that after applying sealant and assembling the bottom plate 20, excess sealant can be guided into the overflow groove 111 during the compression process, preventing breaks or uneven thickness in the sealant layer 24 due to insufficient sealant or uneven compression. This ensures the continuous integrity of the sealing tape, providing reliable protection for a high level of protection. Specifically, in this embodiment, the overflow groove 111 is located at the bottom of the outer frame 11. The outer frame 11 is a key part of the sealing of the lower housing 100; providing the overflow groove 111 here maximizes the continuity and uniformity of the sealant layer 24 in the frame area.

[0043] Furthermore, a cavity 32 is provided between the bottom protective plate 30 and the bottom plate 20. The cavity 32 is filled with a support member 33. Specifically, in this embodiment, the bottom protective plate 30 is configured as an uneven plate-like structure to form a cavity 32 with sufficient volume between the bottom protective plate 30 and the bottom plate 20 to accommodate the support member 33. Specifically, the support member 33 is foam, which can improve the impact protection performance of the bottom of the battery pack.

[0044] In this embodiment, sealing gaskets 34 are provided at the connection between the bottom guard plate 30 and the outer frame 11 of the box frame 10, and at the connection between the bottom guard plate 30 and the inner support beam 12, that is, at the location where the second fastener 31 is set on the bottom guard plate 30. The sealing gaskets 34 are provided between the bottom guard plate 30 and the bottom plate 20 to ensure the seal between the bottom guard plate 30 and the bottom plate 20.

[0045] Please refer to Figure 5 and Figure 6The base plate 20 has a groove 21 on the side facing the housing frame 10. The groove 21 is used to accommodate the protruding structure 201 at the bottom of the battery module 200. The protruding structure 201 at the bottom of the battery module 200 includes, but is not limited to, module cable ties, fixing brackets, or protruding features of the cell housing itself. Through the cooperation of the groove 21 and the protruding structure 201, the battery module 200 can be installed closer to the base plate 20, effectively reducing the overall height of the battery pack and optimizing the overall vehicle space utilization. The groove 21 provides space for the protruding structure 201, avoiding an increase in the gap between the battery module 200 and the base plate 20 due to the support of the protruding structure 201, thereby significantly reducing the amount of structural adhesive required to fill the gap, achieving material cost reduction and further weight reduction.

[0046] Specifically, the assembly process of the lower housing 100 provided in this embodiment of the invention is as follows: First, sealant is continuously applied to the bottom mounting surface of the welded metal housing frame 10 along the preset positions of the outer frame 11 and the inner support beam 12. Next, the pre-formed composite material base plate 20 is aligned and placed on the housing frame 10, ensuring the base plate 20 adheres to the sealant-coated frame surface. Then, the base plate 20 is fixed to the outer frame 11 of the housing frame 10 using the first fastener 22. Before installing the bottom protective plate 30, a support member 33 is laid or pasted on the side of the base plate 20 facing away from the housing frame 10, or the support member 33 is pasted onto the corresponding position on the bottom protective plate 30. The bottom protective plate 30 is aligned with the bottom of the housing frame 10, and the second fastener 31 is used to sequentially pass through the bottom protective plate 30 and the base plate 20 onto the housing frame 10, tightening them to press the bottom protective plate 30, foam support member 33, and base plate 20 together firmly onto the housing frame 10.

[0047] Specifically, in this embodiment, a rivet nut is provided inside the housing frame 10, and the second fastener 31 is a fixing bolt. The bottom guard plate 30 is fixedly connected to the housing frame 10 through the cooperation of the second fastener 31 and the rivet nut. The first fastener 22 is an FDS (flowing drill screw), which fixes the bottom plate 20 to the outer frame 11 of the housing frame 10 through the FDS process. It should be noted that the flowing drill screw (FDS) process is a cold forming process in which the high-speed rotation of the motor is transmitted to the sheet metal to be connected through the central tightening shaft of the equipment, which generates frictional heat and plastic deformation, and then self-tapping screws are screwed together.

[0048] Furthermore, the battery module 200 is bonded and fixed to the side of the base plate 20 facing the inside of the housing frame 10 using structural adhesive. Specifically, structural adhesive is applied to a pre-defined bonding area on the surface of the base plate 20, and then the protruding structure 201 (such as a module cable tie) at the bottom of the battery module 200 is aligned with the corresponding groove 21 on the base plate 20, so that the module falls smoothly and is bonded and fixed to the base plate 20.

[0049] The beneficial effects of the lower housing 100 and battery pack provided in this embodiment of the invention include: The lower housing 100 of the battery pack of the present invention includes a housing frame 10, a bottom plate 20, and a bottom protective plate 30. The housing frame 10 is a metal frame. The bottom plate 20 is a laminated structure composed of multiple continuous fiber layers, with adjacent continuous fiber layers having different fiber layup directions. The bottom plate 20 is fixedly connected to the housing frame 10 by a plurality of first fasteners 22. A sealant layer 24 is provided between the bottom plate 20 and the housing frame 10. The bottom protective plate 30 is fixedly connected to the housing frame 10 by a plurality of second fasteners 31, so that the bottom plate 20 is sandwiched between the bottom protective plate 30 and the housing frame 10. By using a continuous fiber laminated structure to replace the traditional metal bottom plate 20, the high strength and high modulus characteristics of composite materials are fully utilized, significantly reducing the weight of the housing. Among them, the cross-layup design with adjacent fiber layers laid in different directions gives the bottom plate 20 excellent tensile and bending strength in all in-plane directions, ensuring its reliability as the main load-bearing structure. Through the composite connection structure of the base plate 20, the sealant layer 24, and the housing frame 10, the sealant not only provides a sealing function but also enhances the connection rigidity between the base plate 20 and the metal frame, effectively dispersing stress concentration around the fasteners. The outermost bottom protective plate 30 provides direct physical protection against scratches and gravel impacts to the base plate 20. The lower housing 100 of this invention achieves lightweight design of the battery pack lower housing 100 while ensuring the connection strength and sealing reliability between the composite material base plate 20, which serves as the main load-bearing structure, and the metal frame, and improving the overall protective performance of the bottom of the battery pack.

[0050] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A lower housing, characterized in that, include: Box frame, wherein the box frame is a metal frame; The base plate is a laminated structure composed of multiple continuous fiber layers, and the fiber laying directions of two adjacent continuous fiber layers are different; the base plate is fixedly connected to the box frame by multiple first fasteners; a sealant layer is provided between the base plate and the box frame; The bottom protective plate is fixedly connected to the box frame by a plurality of second fasteners, so that the bottom plate is sandwiched between the bottom protective plate and the box frame.

2. The lower housing according to claim 1, characterized in that, The base plate has a thickened structure in the local area where it connects with the first fastener and / or the second fastener.

3. The lower housing according to claim 2, characterized in that, The thickened structure is integrally formed with the base plate and consists of the additionally laid continuous fiber layer.

4. The lower housing according to claim 3, characterized in that, The thickened structure is located on the side of the base plate facing the bottom guard plate.

5. The lower housing according to claim 1, characterized in that, The bottom plate has a groove on the side facing the housing frame, which is used to accommodate the protruding structure at the bottom of the battery module.

6. The lower housing according to claim 1, characterized in that, The box frame includes an outer frame and a plurality of inner support beams disposed within the outer frame; the inner support beams include transverse support beams and longitudinal support beams, and the transverse support beams and the longitudinal support beams are cross-connected.

7. The lower housing according to claim 6, characterized in that, The base plate is fixedly connected to the outer frame via the first fastener; the bottom guard plate is fixedly connected to the outer frame and the inner support beam via the second fastener, wherein at the connection position between the bottom guard plate and the inner support beam, the base plate has a through hole for the second fastener to pass through, so that the base plate is sandwiched between the bottom guard plate and the box frame.

8. The lower housing according to claim 1, characterized in that, An overflow groove is also provided on the side of the box frame facing the bottom plate.

9. The lower housing according to claim 1, characterized in that, A cavity is provided between the bottom protective plate and the bottom plate, and a support member is filled in the cavity.

10. A battery pack, characterized in that, Includes the lower housing as described in any one of claims 1-9.

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