Battery lower box body and battery pack

Abstract

The invention relates to the technical field of lithium battery manufacturing, in particular to a battery lower box body and a battery pack, the battery lower box body comprises a bottom plate and a frame arranged on the periphery of the bottom plate, and the frame and the bottom plate jointly define a containing space for containing a battery module; the frame is of a split structure and comprises an inner frame and an outer frame, and the inner frame is detachably connected with the outer frame. According to the invention, the passive safety performance of the battery system is obviously improved, the buffer structure of the outer frame can effectively absorb and disperse collision impact energy, and the force transmitted to the internal battery cell is reduced; the guiding structure at the bottom can guide an obstacle to the position below the box body during front collision, rigid impact is avoided, and the risk of thermal runaway caused by extrusion and puncture of the battery cells is greatly reduced through double protection.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a battery lower casing and battery pack. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the safety and reliability of battery packs, as core energy storage units, are receiving increasing attention. The lower casing of the battery pack, as a critical load-bearing and protective component, not only needs to provide structural support and physical isolation for the internal cells, modules, and high-voltage lines, but also needs to effectively withstand road impacts and minor bottoming-out conditions during vehicle operation. Furthermore, in the event of a collision, it must absorb energy through structural deformation to prevent the cells from being squeezed or punctured, thereby avoiding serious safety accidents such as thermal runaway.

[0003] Currently, the battery lower casing commonly used in the industry is mostly a one-piece or integrally welded structure, for example, made of welded aluminum alloy profiles. Especially in battery packs using highly integrated designs such as CTP (Cell to Pack), the connection between the lower casing and the internal cell structure is even closer. However, this one-piece design has obvious drawbacks: when the lower casing frame deforms or cracks in a collision, due to its indivisibility or difficulty in repair, it often requires the replacement of the entire battery pack, resulting in high vehicle repair costs and hindering the efficient use of resources.

[0004] To address the need for improved battery pack collision safety, existing technologies have proposed several improvement solutions. For example, Chinese patent CN116454513A discloses a lower battery pack housing that adds side beams with internal reinforcing ribs to the outer side of the frame. These reinforcing ribs employ a negative Poisson's ratio structure or a combination of triangular and horizontal ribs at specific angles, aiming to enhance overall strength and buffering energy absorption. Another example is patent CN108630843A, which provides a battery pack protective frame. This frame is formed by the fixed connection of multiple frame components, integrating sealing, battery securing, and protection functions. Furthermore, patent CN111900280A incorporates an integrated anti-collision panel with a raised structure inside the battery box to absorb impact energy.

[0005] While the aforementioned solutions have made some progress in improving the structural strength, compression resistance, and energy absorption of battery packs, their structure is still essentially a one-piece design or relies on it. Once the protective structure is damaged in a collision, repair or replacement remains extremely inconvenient or even infeasible, failing to fundamentally solve the problem of high post-collision repair costs. Summary of the Invention

[0006] The purpose of this invention is to provide a battery lower housing and battery pack that can effectively improve the battery pack's impact resistance while significantly enhancing its post-collision maintainability.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a battery lower housing, including a base plate and a frame disposed around the base plate, the frame and the base plate together forming a receiving space for accommodating a battery module; the frame is a split structure, including an inner frame and an outer frame, the inner frame and the outer frame being detachably connected.

[0008] Preferably, the outer frame has a buffer structure inside.

[0009] Preferably, the buffer structure is a groove, rib, or hollow cavity formed on the inner sidewall of the outer frame.

[0010] Preferably, a guide structure is provided at the bottom of the outer frame.

[0011] Preferably, the guide structure is an inclined surface or curved surface extending outward and / or downward from the bottom of the outer frame.

[0012] Preferably, the inner frame and the outer frame are connected by one or more of the following methods: bolting, riveting, and snap-fitting.

[0013] Preferably, the inner frame and / or the outer frame are made of aluminum profile, roll-formed steel or pultruded profile.

[0014] Preferably, the split frame structure is located at the front frame position of the lower battery housing.

[0015] A battery pack includes the lower battery housing and a battery module installed within a receiving space of the lower battery housing.

[0016] Preferably, the battery module is arranged in the accommodating space using a CTP structure.

[0017] The beneficial effects of this invention are as follows: First, it significantly improves the passive safety performance of the battery system. The buffer structure of the outer frame effectively absorbs and disperses collision impact energy, reducing the force transmitted to the internal battery cells. The bottom guiding structure can guide obstacles to the bottom of the housing during a frontal collision, avoiding rigid impact. This dual protection greatly reduces the risk of thermal runaway caused by cell compression and puncture. Second, it significantly improves the maintainability and economy of the battery pack. When collision damage occurs, only the damaged outer frame components need to be replaced, without scrapping the entire battery pack or lower housing, greatly reducing the user's maintenance costs and time costs. Third, it enhances the flexibility and manufacturability of the structural design. The split structure allows the inner and outer frames to use different material and process combinations according to performance requirements, potentially reducing overall manufacturing costs while optimizing local performance. In summary, this invention achieves a major breakthrough in maintainability while ensuring high safety, and has significant value for improving the overall safety level and life-cycle economy of electric vehicles. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a battery pack according to an embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the lower casing of the middle battery; Figure 3 for Figure 2 An exploded view of a specific embodiment of the split frame structure; Figure 4 for Figure 3 A schematic diagram of the specific structure of the outer frame described in the diagram; The following are the annotations for the battery: 1: Lower battery housing; 2: Battery module; 11: Frame; 101: Storage space; 112: Outer frame; 1121: Buffer structure; 1122: Guide structure. Detailed Implementation

[0019] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0020] like Figure 1 The diagram shown is a schematic representation of the overall structure of a battery pack according to an embodiment of the present invention. The battery pack mainly includes a lower battery housing 1 and battery modules 2 installed therein. The lower battery housing 1 provides structural support, physical protection, and installation space for the battery modules 2.

[0021] like Figure 2The diagram shows the specific structure of the lower battery housing in this embodiment. The lower battery housing 1 includes a base plate (not shown separately in the diagram, forming the bottom of the accommodating space) and frame edges 11 arranged around the base plate. These frame edges are arranged horizontally and vertically, dividing the base plate into multiple accommodating spaces 101 for the orderly arrangement of the battery modules 2. This structure facilitates the compact layout and thermal management of the battery pack (especially CTP structures).

[0022] The core improvement of this invention lies in the structural design of the frame. Specifically, as shown in... Figure 3 As shown, at least a portion of the frame (preferably the frame at the front of the vehicle where collisions are likely to occur) adopts a split design. Taking one frame as an example, it is composed of a first frame component (specifically, the inner frame 111 in this embodiment) and a second frame component (specifically, the outer frame 112 in this embodiment). The inner frame 111 is mainly used to define the accommodating space 101 and may be connected to an internal module or crossbeam (not shown in the figure). The outer frame 112 constitutes the outermost protective barrier of the lower housing 1.

[0023] The inner frame 111 and the outer frame 112 are detachably connected. In one embodiment, they can be fastened together with bolts; in another embodiment, they can be riveted or have a locking snap-fit ​​structure; or a combination of the above methods can be used. This detachable, split-type connection design is key to achieving "maintainability" in this embodiment. When a vehicle experiences a side or frontal collision, causing the outer frame 112 to be deformed, cracked, or otherwise damaged, maintenance personnel can simply remove the damaged outer frame 112 and replace it with a new component, without having to replace the entire lower housing 1 or the expensive battery pack, thus significantly reducing maintenance costs and time.

[0024] Furthermore, such as Figure 4 The diagram shows the detailed structure of the outer frame 112. To improve its impact resistance (i.e., "energy absorption"), a buffer structure 1121 is designed on the inner wall of the outer frame 112. This buffer structure 1121 can be specifically implemented as a groove extending along the length of the frame, a raised reinforcing rib, or a closed or semi-closed hollow cavity formed by the inner and outer walls. When a collision occurs, the impact force first acts on the outer frame 112. The buffer structure 1121 on its inner side can effectively absorb and dissipate a portion of the impact energy through its own plastic deformation, folding, or crushing, thereby reducing the impact force transmitted to the inner frame 111 and even the internal battery module 2, and improving the passive safety of the battery pack.

[0025] Meanwhile, to address potential obstacles (such as the other vehicle's crash beam or guardrail) encountered in frontal collisions (e.g., frontal or offset collisions), a guide structure 1122 is integrated into the bottom of the outer frame 112. This guide structure 1122 can be a sloping surface extending outwards and downwards from the bottom edge of the outer frame 112, or a smoothly transitioning curved surface. Its working principle is as follows: in the event of a frontal collision, the obstacle will contact the guide structure 1122 before or simultaneously with the outer frame 112. Guided by the sloping or curved surface of the guide structure 1122, the obstacle will generate a downward component force, changing its direction of motion and thus being "guided" to slide under the bottom of the battery lower housing 1, or at least reducing the severity of its direct frontal impact on the outer frame 112. This is equivalent to adding a "sliding" protection mechanism to the battery pack, further protecting the outer frame 112 and its internal structure, and significantly improving frontal collision safety.

[0026] Regarding materials and manufacturing processes, the inner frame 111 and outer frame 112 can be flexibly selected and combined according to performance, weight, and cost requirements. For example, both can be made from lightweight aluminum alloy profiles through extrusion; or, to pursue higher strength and cost-effectiveness, they can be made from roll-formed steel sheets; or composite material pultruded profiles can be used. A preferred combination is that the inner frame 111 uses aluminum profiles to reduce weight and facilitate heat dissipation, while the outer frame 112 uses high-strength roll-formed steel or aluminum profiles with specific cross-sections (such as those containing buffer cavities) to balance protective strength and lightweight design.

[0027] For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention. For example, the split frame structure can be applied to all peripheries of the lower box body, not just the front, or the specific shapes of the buffer structure 1121 and the guide structure 1122 can be optimized to suit different vehicle platforms. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A battery lower casing, characterized in that, It includes a base plate and a frame (11) disposed around the base plate. The frame (11) and the base plate together form a receiving space (101) for accommodating the battery module (2). The frame (11) is a split structure, including an inner frame (111) and an outer frame (112). The inner frame (111) and the outer frame (112) are detachably connected.

2. The battery lower housing according to claim 1, characterized in that, The outer frame (112) has a buffer structure (1121) inside.

3. The lower battery housing according to claim 2, characterized in that, The buffer structure (1121) is a groove, rib or hollow cavity formed on the inner sidewall of the outer frame (112).

4. The lower battery housing according to any one of claims 1 to 3, characterized in that, The bottom of the outer frame (112) is provided with a guide structure (1122).

5. The lower battery housing according to claim 4, characterized in that, The guide structure (1122) is a slope or curved surface that extends outward and / or downward from the bottom of the outer frame (112).

6. The lower battery housing according to claim 1, characterized in that, The inner frame (111) and the outer frame (112) are connected by one or more of the following methods: bolt connection, riveting, and snap-fit.

7. The lower battery housing according to claim 1, characterized in that, The inner frame (111) and / or the outer frame (112) are made of aluminum profile, rolled steel or pultruded profile.

8. The lower battery housing according to claim 1, characterized in that, The split-type frame structure is located at the front frame position of the lower battery housing.

9. A battery pack, characterized in that, It includes a battery lower housing (1) as described in any one of claims 1 to 8, and a battery module (2) installed in the receiving space (101) of the battery lower housing (1).

10. The battery pack according to claim 9, characterized in that, The battery module (2) is arranged in the accommodating space (101) using a CTP structure.

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