Lightweight carbon fiber battery box

Abstract

The utility model discloses a lightweight carbon fiber battery box, and belongs to the technical field of automobile parts prepared from composite materials. According to the utility model, the problem that the strength of the battery box cannot be ensured while the weight of the battery box is reduced due to the adoption of the existing metal battery box for the electric automobile is solved. The outer frame and the upper cover are both of a laminated structure and comprise a plurality of carbon fiber reinforced composite material layers, the surrounding plate is an aluminum plate, the surrounding plate is arranged on the periphery of the outer frame in a surrounding mode, the bottom plate is an aluminum plate, the bottom plate is fixedly connected with double rows of curved surface ribs and double rows of grid ribs, the bottom plate is welded to the bottom of the surrounding plate, the upper cover is connected with the top of the outer frame, and the mounting strips are aluminum strips. The mounting strip is welded at the bottom of the coaming. According to the lightweight carbon fiber battery box, the carbon fiber reinforced composite material and the aluminum plate material are combined, so that the strength of the battery box is improved while the weight of the battery box is reduced, the safety of the lightweight carbon fiber battery box is ensured, and the lightweight and cruising ability of a vehicle is favorably improved.

Description

Technical Field

[0001] This utility model relates to a lightweight carbon fiber battery box, belonging to the technical field of composite material preparation for automotive parts. Background Technology

[0002] Currently, most electric vehicle battery boxes manufactured by automakers use metal materials, such as aluminum alloys. While metal materials possess high structural strength, their high density and weight ratio lead to a decrease in the energy density of the battery system. Reducing the weight of the metal materials used in the battery box compromises its strength and rigidity, compromising safety. Considering replacing metal materials with other options, the strength, thermal conductivity, and price of these alternatives must be superior to those of metal, and they should be lighter than metal for the same thickness. For example, PC or PP plastics, while significantly lighter than metal, have much lower strength and flame retardancy than metal. Even flame-retardant plastics are more expensive to manufacture than metal. Furthermore, most existing battery boxes have a box-like structure. When the battery is placed inside, the material properties of metal can easily cause deformation of the bottom surface of the battery box, leading to battery displacement, stress concentration areas, and even fatigue cracks, shortening the battery box's lifespan and reducing its safety. Therefore, existing electric vehicle battery boxes suffer from the problem of failing to reduce battery box weight while ensuring battery box strength, and the battery box structure leads to a severe reduction in battery box lifespan, which restricts vehicle lightweighting and range improvement. Utility Model Content

[0003] The present invention aims to solve the above-mentioned problems and thereby provide a lightweight carbon fiber battery box.

[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows:

[0005] A lightweight carbon fiber battery box includes a top cover, an outer frame, a surrounding panel, a bottom plate, and mounting strips. The outer frame and the top cover are both laminated structures, including multiple layers of carbon fiber reinforced composite material. The surrounding panel is an aluminum plate that surrounds the perimeter of the outer frame. The bottom plate is an aluminum plate with double rows of curved ribs and double rows of mesh ribs fixedly attached to it. The bottom plate is welded to the bottom of the surrounding panel. The top cover is connected to the top of the outer frame. The mounting strips are aluminum strips that are welded to the bottom of the surrounding panel.

[0006] Furthermore, the mounting strip and the surrounding plate, as well as the surrounding plate and the bottom plate, are welded using tungsten inert gas welding.

[0007] Furthermore, the mounting strip is provided with mounting strip positioning holes and mounting strip mounting holes for positioning and connection with other parts.

[0008] Furthermore, the upper cover and the outer frame are positioned and connected by locating pins.

[0009] Furthermore, the top array of the upper cover has multiple rectangular slots.

[0010] Furthermore, the thickness of the double-row curved ribs gradually decreases by 30%-35% from the bottom to the top.

[0011] Furthermore, the double-row curved ribs and double-row mesh ribs are distributed in a contour-following manner along the battery pack mounting area on the base plate.

[0012] Furthermore, the base plate is provided with multiple weight-reduction holes.

[0013] Furthermore, each of the carbon fiber reinforced composite material layers includes a honeycomb core layer and two carbon fiber skin layers. The honeycomb core layer is fixed between the two carbon fiber skin layers. The honeycomb core layer uses closed-cell aramid as the matrix and is composed of a rigid skeleton formed by resin impregnation and curing.

[0014] Furthermore, the mounting strip also includes two arc-shaped legs, which are positioned opposite each other at one end of the mounting strip near the outer frame.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] This application strengthens the floor structure by fixing double rows of curved ribs and double rows of mesh ribs to the base plate, providing stronger support for high-stress areas, effectively dispersing local stress concentration, and preventing fatigue cracks. The double rows of curved ribs and double rows of mesh ribs form a continuous support network, significantly improving the overall shell stiffness to a bending stiffness ≥4500 N·mm. 2 Energy absorption efficiency is improved by more than 25% under collision conditions;

[0017] The top cover and outer frame of this application are both made of carbon fiber reinforced composite material, which reduces weight by 30%-40% compared with aluminum alloy and has a specific stiffness 3-5 times that of aluminum alloy. The outer frame is covered by a surrounding panel, which can suppress the risk of fragment peeling from the carbon fiber laminate structure. The bottom plate is reinforced with aluminum plate to achieve a balance between local impact resistance and global load-bearing capacity. This application combines carbon fiber reinforced composite material and aluminum plate material to reduce the weight of the battery box while improving its strength, ensuring the safety of the lightweight carbon fiber battery box and contributing to the improvement of vehicle lightweighting and range. Attached Figure Description

[0018] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0019] Figure 1 A three-dimensional structural diagram of a lightweight carbon fiber battery box;

[0020] Figure 2 This is a schematic diagram of the upper cover of a lightweight carbon fiber battery box.

[0021] Figure 3 for Figure 2 Enlarged view of a portion of point A in the middle;

[0022] Figure 4 This is a schematic cross-sectional view of a carbon fiber reinforced composite material.

[0023] Figure 5 This is a schematic diagram showing the positional relationship between the outer frame and the surrounding panels in a lightweight carbon fiber battery box.

[0024] Figure 6 for Figure 5 Enlarged view of a section at point B in the middle;

[0025] Figure 7 A schematic diagram of the base plate of the lightweight carbon fiber battery box;

[0026] Figure 8 for Figure 7 Enlarged view of a section at point C;

[0027] Figure 9 A three-dimensional structural diagram of the mounting strip in a lightweight carbon fiber battery box.

[0028] Figure 10 A schematic diagram showing the connection relationship between the mounting strips, surrounding panels, and base plate in a lightweight carbon fiber battery box;

[0029] In the diagram: 1. Top cover; 2. Outer frame; 3. Base plate; 4. Mounting strip; 5. Enclosure panel; 6. Double-row curved ribs; 7. Double-row mesh ribs; 8. Weight reduction hole; 9. Top cover mounting hole; 10. Top cover positioning hole; 11. Outer frame mounting hole; 12. Outer frame positioning hole; 13. Mounting strip mounting hole; 14. Mounting strip positioning hole; 15. Honeycomb sandwich core; 16. Carbon fiber skin; 17. Arc-shaped support leg; 18. Rectangular groove. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0031] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] The preferred embodiments of this disclosure are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0033] See appendix Figure 1-10 This embodiment describes a lightweight carbon fiber battery box, comprising a top cover 1, an outer frame 2, a surrounding panel 5, a bottom plate 3, and mounting strips 4. Both the outer frame 2 and the top cover 1 are laminated structures, comprising multiple layers of carbon fiber reinforced composite material. The surrounding panel 5 is an aluminum plate, surrounding the perimeter of the outer frame 2. The bottom plate 3 is an aluminum plate, with double rows of curved ribs 6 and double rows of mesh ribs 7 fixedly attached to it. The bottom plate 3 is welded to the bottom of the surrounding panel 5. The top cover 1 is connected to the top of the outer frame 2. The mounting strips 4 are aluminum strips, welded to the bottom of the surrounding panel 5. Specifically, the thickness of the top cover 1 is 2-3 mm, the thickness of the surrounding panel 5 is 5 mm, and the materials of the surrounding panel 5, bottom plate 3, and mounting strips 4 are all 7075 aluminum.

[0034] The top cover 1 and outer frame 2 of this application are both made of carbon fiber reinforced composite material to effectively block the heat conduction path and improve the heat dissipation uniformity. The interlaminar shear strength and in-plane stiffness of the carbon fiber reinforced composite material are synergistically controlled to match the stress distribution in each area of ​​the battery box, avoiding local buckling or delamination failure. The damping effect reduces the vibration noise of the battery pack during operation. Its vertical compressive strength is ≥8MPa, the collision energy absorption rate is more than 50% higher than that of solid structure, and the specific stiffness is 3-5 times that of aluminum alloy, achieving a 40% reduction in thickness under the same load. Compared to aluminum alloy, this material reduces weight by 30%-40% and has a stiffness 3-5 times that of aluminum alloy. The outer frame of this application is surrounded by a panel 5. When the battery box is subjected to lateral impact, the panel can suppress the risk of fragment peeling from the carbon fiber laminate structure of the outer frame, reducing the degree of damage to the outer frame. Through the combination of carbon fiber reinforced composite material and aluminum plate material, the weight of the battery box is reduced while its strength is improved, ensuring the safety of the lightweight carbon fiber battery box and contributing to vehicle lightweighting and improved range. The base plate 3 of this application is reinforced with aluminum plate to achieve a balance between local impact resistance and overall load-bearing capacity. Simultaneously, double rows of curved ribs and double rows of mesh ribs are fixed to the base plate to strengthen the structure of the floor, providing stronger support for high-stress areas, effectively dispersing local stress concentration, and preventing fatigue cracks. The double rows of curved ribs and double rows of mesh ribs form a continuous support network, significantly improving the overall stiffness of the shell to a bending stiffness ≥4500 N·mm. 2 Energy absorption efficiency is improved by more than 25% under collision conditions.

[0035] The mounting strip 4 and the surrounding plate 5, as well as the surrounding plate 5 and the base plate 3, are welded using tungsten inert gas (TIG) welding. Due to the limitations of 7075 aluminum in terms of weldability, TIG welding is employed, using high-purity argon gas and preheating to 150-200℃ to reduce cracks and porosity and improve connection reliability. ER5356 welding wire is used. Post-weld treatments include solution treatment, aging treatment, and anodizing to restore the strength of the heat-affected zone and improve corrosion resistance.

[0036] The mounting strip 4 is provided with mounting strip positioning holes 14 and mounting strip mounting holes 13 for positioning and connection with the vehicle frame. The upper cover 1 and the outer frame 2 are positioned and connected by positioning pins. Specifically, the upper cover 1 is provided with upper cover positioning holes 10 and upper cover mounting holes 9, and the outer frame 2 is provided with outer frame positioning holes 12 and outer frame mounting holes 11. The upper cover 1 and outer frame 2 are positioned by the upper cover positioning holes 10 and outer frame positioning holes 12, and the upper cover 1 and outer frame 2 are fixed by bolts between the upper cover mounting holes 9 and outer frame mounting holes 11 to improve the strength of the lightweight carbon fiber battery box and ensure its safety.

[0037] The top of the upper cover 1 has multiple rectangular slots 18 arranged in an array. Specifically, the rectangular slots 18 are 1mm deep and arranged in an array to reduce the weight of the upper cover 1, thereby reducing the overall weight of the lightweight carbon fiber battery box, which helps to reduce vehicle weight and improve range.

[0038] The thickness of the double-row curved ribs 6 gradually decreases by 30%-35% from the bottom to the top. Specifically, the thickness at the connection between the double-row curved ribs 6 and the base plate 3 is 3mm, and the thickness at the top of the double-row curved ribs 6 is 2mm. While ensuring that the double-row curved ribs 6 can improve the overall rigidity of the base plate 3, the gradual thickness design reduces the weight ratio of the double-row mesh ribs 7 and the double-row curved ribs 6 to less than 15% of the total weight of the lightweight carbon fiber battery box, achieving a 15% weight reduction compared to the traditional uniformly distributed reinforcing rib solution, while simultaneously improving bending stiffness and impact energy absorption efficiency.

[0039] The double-row curved ribs 6 and double-row grid ribs 7 are distributed in a contour-following manner along the battery pack mounting area on the base plate 3. Based on the weight distribution of the battery modules mounted on the base plate 3 and vehicle operating loads such as vibration, impact, and bending, they are arranged in a gradient to provide stronger support in high-stress areas. The double-row grid ribs 7 and double-row curved ribs 6 form a continuous support network, significantly improving the overall rigidity of the shell to a bending rigidity ≥4500 N·mm. 2 Under collision conditions, energy absorption efficiency is improved by more than 25%. The double-row curved ribs 6 adopt a rounded transition structure, which effectively disperses local stress concentration and avoids fatigue cracks.

[0040] Multiple weight-reduction holes 8 are provided on the base plate 3. Specifically, the weight-reduction holes 8 are all located between the double rows of grid ribs 7. By providing weight-reduction holes 8 on the base plate 3, the overall weight of the lightweight carbon fiber battery box can be reduced while ensuring a balance between the local impact resistance and the overall load-bearing capacity of the base plate 3.

[0041] Each of the aforementioned carbon fiber reinforced composite material layers includes a honeycomb core layer 15 and two carbon fiber skin layers 16. The honeycomb core layer 15 is fixed between the two carbon fiber skin layers 16. The honeycomb core layer 15 uses closed-cell aramid as the matrix and is composed of a rigid skeleton formed by resin impregnation and curing. The thermal conductivity of the air cavity inside the honeycomb core 15 matrix is ​​≤0.5W / (m·K), which can effectively block the heat conduction path. The layout of the lower shell reinforcing ribs works in conjunction with the cooling channels to achieve thermal barrier and heat dissipation synergy, improving heat dissipation uniformity. At the same time, the honeycomb core 15 matrix is ​​matched with the stress distribution in each area of ​​the battery box through the coordinated control of interlaminar shear strength and in-plane stiffness, avoiding local buckling or delamination failure; and the damping effect reduces the vibration noise of the battery pack during operation. The vertical compressive strength of the honeycomb core 15 is ≥8MPa, the impact energy absorption rate is more than 50% higher than that of a solid structure, the specific stiffness is 3-5 times that of aluminum alloy, and the thickness is reduced by 40% under the same load.

[0042] The mounting strip 4 also includes two arc-shaped support legs 17, which are positioned opposite each other at one end of the mounting strip 4 near the outer frame 2. The arc-shaped support legs 17 can improve the stability of the connection between the mounting strip 4 and the enclosure 5. At the same time, the arc-shaped support legs 17 can improve the compatibility of the lightweight carbon fiber battery box with the vehicle frame, making it easier to maintain and upgrade the lightweight carbon fiber battery box.

[0043] Obviously, the above-disclosed embodiments of the present invention are merely for illustrating the present invention. The embodiments do not exhaustively describe all details, nor do they limit the present invention to specific implementations. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. It is neither necessary nor possible to exhaustively describe all implementation methods here.

Claims

1. A lightweight carbon fiber battery box, characterized in that: The structure includes an upper cover (1), an outer frame (2), a surrounding panel (5), a bottom plate (3), and a mounting strip (4). The outer frame (2) and the upper cover (1) are both laminated structures, including multiple carbon fiber reinforced composite material layers. The surrounding panel (5) is an aluminum plate, which surrounds the outer frame (2). The bottom plate (3) is an aluminum plate, with double-row curved ribs (6) and double-row grid ribs (7) fixed on it. The bottom plate (3) is welded to the bottom of the surrounding panel (5). The upper cover (1) is connected to the top of the outer frame (2). The mounting strip (4) is an aluminum strip, which is welded to the bottom of the surrounding panel (5). The thickness of the double-row curved ribs (6) gradually decreases by 30%-35% from the bottom to the top. The double-row curved ribs (6) and double-row grid ribs (7) are distributed in a contour-following manner along the battery pack mounting area on the base plate (3); Each of the carbon fiber reinforced composite material layers includes a honeycomb sandwich layer (15) and two carbon fiber skin layers (16). The honeycomb sandwich layer (15) is fixed between the two carbon fiber skin layers (16). The honeycomb sandwich layer (15) is composed of a rigid skeleton formed by using closed-cell aramid as the matrix and then impregnating and curing with resin.

2. The lightweight carbon fiber battery box according to claim 1, characterized in that: The mounting strip (4) and the surrounding plate (5) are welded together, as are the surrounding plate (5) and the bottom plate (3), by tungsten inert gas welding.

3. The lightweight carbon fiber battery box according to claim 1, characterized in that: The mounting strip (4) is provided with mounting strip positioning holes (14) and mounting strip mounting holes (13).

4. A lightweight carbon fiber battery box according to claim 1, characterized in that: The upper cover (1) and the outer frame (2) are positioned and connected by positioning pins.

5. A lightweight carbon fiber battery box according to claim 1, characterized in that: The top array of the cover (1) has multiple rectangular slots (18).

6. A lightweight carbon fiber battery box according to claim 1, characterized in that: Multiple weight-reducing holes (8) are provided on the base plate (3).

7. A lightweight carbon fiber battery box according to claim 1, characterized in that: The mounting strip (4) includes two arc-shaped legs (17), which are positioned opposite each other at one end of the mounting strip (4) near the outer frame (2).

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