Composite protective structure for battery packs and vehicles

Abstract

Composite protective structure for battery pack and vehicle. The composite protective structure for battery pack includes a battery pack and a battery protection bottom plate, the battery protection bottom plate includes a metal plate, the battery protection bottom plate is located below the battery pack, and a buffer area is formed between the battery pack and the battery protection bottom plate, and the buffer area and the metal plate satisfy the following condition (I): d is the thickness (mm) of the metal plate, σ is the tensile strength (MPa) of the metal plate, ε is the breaking elongation of the metal plate, and h is the height (mm) of the buffer area.

Description

Technical Field

[0001] Cross - reference to Related Applications This disclosure claims the priority and benefit of Chinese Patent Application No. 202210612018.1, titled "BATTERY PACK composite protection structure AND VEHICLE", filed on May 31, 2022, the entire content of which is incorporated herein by reference.

[0002] This disclosure belongs to the technical field of vehicle batteries, and more specifically, relates to a composite protection structure for battery packs and vehicles.

Background Art

[0003] The battery packs of new energy electric vehicles are generally arranged at the bottom of the vehicle. In order to avoid damage to the battery packs caused by impacts from hard objects such as stones and metals at the bottom of the vehicle, a protection structure needs to be arranged at the bottom of the battery packs.

[0004] Existing battery pack protection structures still have problems of insufficient protection performance and high manufacturing costs. This is mainly manifested in that the battery pack protection structure is insufficient, the battery is affected by impact vibration, and its service life is shortened under long - term vibration conditions, and cracks or damage to the surface layer of the protection plate are caused by excessive amplitude of the protection plate. The requirements for the strength of the protection plate have been raised, and it is difficult for conventional steel plates to meet these requirements.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the problem of insufficient protection performance of existing battery pack protection structures, this disclosure provides a composite protection structure for battery packs and a vehicle.

Means for Solving the Problems

[0006] To resolve the aforementioned technical problems, the technical solutions adopted in this disclosure are as follows:

[0007] According to one embodiment, the present disclosure provides a composite protective structure for a battery pack, comprising a battery pack and a battery protective bottom plate. The battery protective bottom plate includes a metal plate. The battery protective bottom plate is positioned below the battery pack. A buffering area is formed between the battery pack and the battery protective bottom plate. The buffering area and the metal plate satisfy the following conditions:

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[0008] In some embodiments, the buffer region and the metal plate satisfy the following conditions.

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[0009] In some embodiments, the thickness d of the metal plate is 0.7 to 1.5 mm.

[0010] In some embodiments, the tensile strength σ of the metal plate is 590 to 1180 MPa.

[0011] In some embodiments, the elongation ε of the metal plate at break is 0.05~0.2 That is the case.

[0012] In some embodiments, the height h of the buffer area is 4 to 12 mm.

[0013] In some embodiments, the battery protection bottom plate further includes an upper fiber-reinforced resin layer, a fiber-reinforced resin frame, and a lower fiber-reinforced resin layer. A metal plate is located between the upper fiber-reinforced resin layer and the lower fiber-reinforced resin layer. The metal plate is located inside the fiber-reinforced resin frame. The top surface of the fiber-reinforced resin frame and the upper fiber-reinforced resin layer are integrally connected. The bottom surface of the fiber-reinforced resin frame and the lower fiber-reinforced resin layer are integrally connected.

[0014] In some embodiments, the upper fiber-reinforced resin layer, the metal plate, and the lower fiber-reinforced resin layer all have a rectangular sheet structure. The fiber-reinforced resin frame has a sheet-like rectangular frame structure.

[0015] In some embodiments, a plurality of first mounting holes are formed at intervals on the inside of the edge of the battery protection bottom plate. The first mounting holes penetrate the upper fiber-reinforced resin layer, the fiber-reinforced resin frame, and the lower fiber-reinforced resin layer in that order. A plurality of second mounting holes are formed in the bottom frame of the battery pack to correspond to the positions of the first mounting holes. A connector passes between the first and second mounting holes.

[0016] In some embodiments, the upper fiber-reinforced resin layer, the fiber-reinforced resin frame, and the lower fiber-reinforced resin layer are independently selected from glass fiber-reinforced polyamide resin components, glass fiber-reinforced polypropylene resin components, glass fiber-reinforced polyethylene resin components, glass fiber-reinforced polycarbonate resin components, or glass fiber-reinforced polystyrene resin components.

[0017] In some embodiments, the buffer region is filled with a buffer layer, which is made from a honeycomb material or a rigid foam material.

[0018] In some embodiments, the metal sheet is a steel sheet, and a zinc coating, a zinc-iron alloy coating, or an electrophoretic coating protective layer is applied to the outer surface of the steel sheet.

[0019] According to another aspect, the present disclosure provides a vehicle including the composite protection structure for a battery pack described above.

[0020] According to the composite protection structure for a battery pack provided by the present disclosure, the battery protection bottom plate is disposed on the lower side of the battery pack, while the buffer region is disposed between the battery pack and the battery protection bottom plate. The inventor has found through a number of experiments that the material of the metal plate and the height of the buffer region of the battery protection bottom plate have a significant correlation with the realization of a good buffering effect and a protection effect. Specifically, the thickness d of the metal plate, the tensile strength σ of the metal plate, the elongation at break ε of the metal plate, and the height h of the buffer region are

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Brief Description of the Drawings

[0021] [Figure 1] It is a schematic structural diagram of a composite protection structure for a battery pack according to an embodiment of the present disclosure. [Figure 2] It is an enlarged view of part A in FIG. 1. [Figure 3] It is a schematic structural diagram of a battery protection bottom plate according to an embodiment of the present disclosure. [Figure 4] It is a schematic cross-sectional view of the bottom of a composite protection structure for a battery pack according to an embodiment of the present disclosure. [Figure 5] It is a schematic cross-sectional view of the bottom of a composite protection structure for a battery pack according to an embodiment of the present disclosure. [Figure 6] It is a schematic cross-sectional view of the bottom of a composite protection structure for a battery pack according to an embodiment of the present disclosure. [Figure 7] It is a schematic diagram of a vehicle according to an embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0022] To further clarify the technical problems to be addressed, the technical solutions and beneficial effects of this disclosure, this disclosure is described in more detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are not limiting to this disclosure, but are merely used to illustrate it.

[0023] In the description of this disclosure, orientations or positional relationships indicated by terms such as “upper,” “lower,” “top,” “bottom,” “inside,” and “outside” are based on the orientations or positional relationships shown in the accompanying drawings and should not indicate or suggest that the devices or elements referred to have a particular orientation or need to be constructed and operated in a particular orientation, but are merely used to describe this disclosure and to simplify the description. Therefore, such terms should not be construed as limitations on this disclosure. In the description of this disclosure, unless otherwise specified, “multiple” means two or more.

[0024] Referring to Figures 1, 3, and 4, this disclosure provides a composite protective structure 10 for a battery pack, comprising a battery pack 3 and a battery protective bottom plate 1. The battery protective bottom plate 1 includes a metal plate 12. The battery protective bottom plate 1 is positioned below the battery pack 3. A buffer area 4 is formed between the battery pack 3 and the battery protective bottom plate 1. The buffer area 4 and the metal plate 12 satisfy the following conditions:

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[0025] Through numerous experiments, the inventors found that the material of the metal plate 12 and the height of the buffer region 4 of the battery protection bottom plate 1 have a significant correlation with achieving good buffering and protective effects. Specifically, the thickness d of the metal plate 12, the tensile strength σ of the metal plate 12, the elongation at break ε of the metal plate 12, and the height h of the buffer region 4 are correlated.

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[0026] In this disclosure, "height of buffer area 4" refers to the maximum distance between the battery protection bottom plate 1 and the battery pack 3.

[0027] In some embodiments, the battery pack 3 includes a tray 31 and batteries placed on the tray 31.

[0028] In different embodiments, the buffer area 4 may be arranged in a different manner between the battery pack 3 and the battery protective bottom plate 1.

[0029] As shown in Figure 4, in one embodiment, grooves are formed inward on the bottom surface of the tray 31 to form a buffer area 4. The battery protection bottom plate 1 is flat. The battery protection bottom plate 1 covers the buffer area 4.

[0030] As shown in Figure 5, in one embodiment, the frame of the battery protection bottom plate 1 is connected to the bottom surface of the tray 31. An inward-facing groove is formed on the bottom surface of the tray 31. The battery protection bottom plate 1 protrudes away from the tray 31, forming a buffer area 4 between the tray 31 and the battery protection bottom plate 1.

[0031] As shown in Figure 6, in one embodiment, the frame of the battery protection bottom plate 1 is connected to the bottom surface of the tray 31. The bottom surface of the tray 31 is flat. The battery protection bottom plate 1 protrudes away from the tray 31, forming a buffer area 4 between the tray 31 and the battery protection bottom plate 1.

[0032] In some embodiments, the buffer region 4 and the metal plate 12 satisfy the following conditions.

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[0033] There is a correlation between the thickness d of the metal plate 12, the tensile strength σ of the metal plate 12, the elongation at break ε of the metal plate 12, and the height h of the buffer area 4. This allows for some degree of integration of the influence of the material selection of the metal plate 12 and the arrangement of the buffer area 4 on the protective performance of the battery pack 3, making it possible to obtain a composite protective structure 10 for a battery pack with excellent safety performance.

[0034] In some embodiments, the thickness d of the metal plate 12 is 0.7 to 1.5 mm.

[0035] Specifically, the thickness d of the metal plate 12 may be 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc.

[0036] The thickness d of the metal plate 12 affects the overall mechanical strength of the battery protection base plate 1. When the tensile strength and elongation at break of the metal plate 12 are constant, the protective strength of the metal plate 12 progressively improves with increasing thickness. However, the material cost of the metal plate 12 progressively increases, the distance between the metal plate 12 and the ground decreases, and the possibility of impact increases. When the thickness d of the metal plate 12 is within the aforementioned range, the overall mechanical strength of the battery protection base plate 1 can be ensured, thereby effectively controlling costs, ensuring sufficient distance from the ground, and contributing to weight reduction of the vehicle 100.

[0037] In some embodiments, the tensile strength σ of the metal plate 12 is 590 to 1180 MPa.

[0038] Specifically, the tensile strength σ of the metal plate 12 may be 590 MPa, 600 MPa, 650 MPa, 700 MPa, 750 MPa, 800 MPa, 850 MPa, 900 MPa, 950 MPa, 1000 MPa, 1180 MPa, etc.

[0039] In some embodiments, the elongation ε of the metal plate 12 at break is 0.05~0.2 That is the case.

[0040] Specifically, the elongation ε at break of the metal plate 12 may be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0041] The tensile strength σ and elongation at break ε of the metal plate 12 may be tested according to "Part 1: Test methods at room temperature for metallic materials - Tensile testing" GB / T 228.1-2010. As the component that provides the primary protective effect in the battery protective bottom plate 1, the metal plate 12 is subjected to complex impact conditions. The tensile strength σ of the metal plate 12, as a strength indicator of the metal plate 12, affects the deformation resistance of the metal plate 12 within its elastic deformation range. A higher tensile strength σ allows the metal plate 12 to withstand stronger impacts without irreversible deformation. The elongation at break ε affects the crack resistance of the metal plate 12 after deformation. A higher elongation at break ε allows the metal plate 12 to withstand stronger impacts without cracking. Generally, the higher the tensile strength σ of the metal plate 12, the lower the elongation at break ε of the metal plate 12. When the tensile strength σ and the elongation at break ε are within the aforementioned ranges, the influence of different parameters on the protective performance of the metal sheet can be effectively considered, and the impact resistance and crack resistance of the metal sheet 12 are ensured.

[0042] In some embodiments, the height h of the buffer area 4 is 4 to 12 mm.

[0043] Specifically, the height h of the buffer area 4 may be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, etc.

[0044] The height h of the buffer region 4 affects the vibration damping performance of the battery pack 3 and also affects the vibration range of the metal plate 12. When the height h of the buffer region 4 is within the aforementioned range, in one embodiment, the vibration damping effect of the battery is improved, and in another embodiment, problems such as material layering and rivet detachment caused by excessive amplitude of the metal plate 12 are avoided.

[0045] In actual application, the four parameters mentioned above are interrelated and inseparable in ensuring the impact resistance and crack resistance of the battery pack 3. For example, increasing the thickness d of the metal plate 12 improves the impact resistance of the battery protection bottom plate 1. In this case, the requirements for the tensile strength σ of the metal plate 12, the elongation at break ε of the metal plate 12, and the height h of the buffer area 4 can be reduced accordingly. However, in response, the material cost of the battery protection bottom plate 1 increases, the overall weight of the vehicle 100 increases, and the distance from the ground decreases. Increasing the tensile strength σ of the metal plate 12 improves the impact resistance and deformation resistance of the metal plate 12. However, the elongation at break ε of the metal plate 12 decreases accordingly, where elongation at break makes it more prone to cracking after deformation. When different tensile strengths σ and different elongations at break ε are selected, the requirements for the minimum thickness differ. As the fracture elongation ε of the metal plate 12 increases, the height h of the buffer region 4 needs to be increased accordingly to provide sufficient buffering space. Increasing the height h of the buffer region 4 improves the buffering and shock absorption effect of the buffer region 4 on the battery pack 3, but it also increases the vibration amplitude of the metal plate 12 during impact, raises the requirement for the tensile strength σ of the metal plate 12, and shortens the distance from the bottom of the vehicle 100 to the ground. Therefore, the influence of various factors on the protective performance of the battery pack 3 is...

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[0046] As shown in Figure 3, in some embodiments, the battery protection bottom plate 1 further includes an upper fiber-reinforced resin layer 11, a fiber-reinforced resin frame 13, and a lower fiber-reinforced resin layer 14. The metal plate 12 is located between the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14. The metal plate 12 is located inside the fiber-reinforced resin frame 13. The top surface of the fiber-reinforced resin frame 13 and the upper fiber-reinforced resin layer 11 are integrally connected. The bottom surface of the fiber-reinforced resin frame 13 and the lower fiber-reinforced resin layer 14 are integrally connected.

[0047] The upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14 are compounded onto the front (positive surface) and back (negative surface) of the metal plate 12. In one embodiment, the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14 can improve the corrosion resistance of the metal plate 12. On the other hand, the lower fiber-reinforced resin layer 14 can withstand impacts such as stones to the bottom of the battery protection bottom plate 1, thus avoiding corrosion problems at the impact point. In another embodiment, after the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14 are compounded onto the metal plate 12, the rigidity and strength of the metal plate 12 are effectively increased, thereby giving the metal plate 12 higher impact resistance.

[0048] On the other hand, the fiber-reinforced resin frame 13 is positioned on the outer periphery of the metal plate 12 as a connection transition portion in the frame of the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14. This effectively eliminates the influence of the thickness of the metal plate 12 on the connection of the frame of the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14, thereby ensuring the strength of the frame of the battery protection bottom plate 1. This facilitates the adoption of the frame of the battery protection bottom plate 1 as a mounting structure for the battery protection bottom plate 1 to the battery pack 3, and improves the impact resistance of the battery protection bottom plate 1.

[0049] In some embodiments, the upper fiber-reinforced resin layer 11, the metal plate 12, and the lower fiber-reinforced resin layer 14 all have a rectangular sheet structure. The fiber-reinforced resin frame 13 has a sheet-like rectangular frame structure. Note that a rectangular sheet structure refers to a structure whose overall shape is generally rectangular. A sheet-like rectangular frame structure refers to a structure whose overall shape is generally rectangular, and modifications may be made if the position of some details does not affect the overall shape. For example, the corners of the rectangle may be set as rounded corners, or protrusions or grooves may be formed on the edges of the rectangle, and the shape of the battery pack may be better adapted by using the generally rectangular structure described above.

[0050] In some embodiments, the shapes of the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14 are identical in order to ensure connection stability between them.

[0051] The shapes of the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14 are designed to fit the shape of the bottom of the battery pack 3. In other embodiments, if the battery pack 3 has a different shape, the upper fiber-reinforced resin layer 11 and the lower fiber-reinforced resin layer 14 may have other fitting shapes, such as triangles, pentagons, and hexagons.

[0052] As shown in Figure 2, a plurality of first mounting holes 15 are formed at intervals on the inside of the edge of the battery protection bottom plate 1. The first mounting holes 15 penetrate the upper fiber-reinforced resin layer 11, the fiber-reinforced resin frame 13, and the lower fiber-reinforced resin layer 14 in that order.

[0053] Multiple second mounting holes 32 are formed in the bottom frame of the battery pack 3 so as to correspond to the positions of the first mounting holes 15. The connector passes through the space between the first mounting holes 15 and the second mounting holes 32.

[0054] The first mounting holes 15 and the second mounting holes 32 are configured to attach and fasten the battery protection bottom plate 1 to the bottom of the battery pack 3. The first mounting holes 15 are formed at intervals on the inside of the edge of the battery protection bottom plate 1 and pass through the upper fiber-reinforced resin layer 11, the fiber-reinforced resin frame 13, and the lower fiber-reinforced resin layer 14 in sequence. This prevents the first mounting holes 15 from penetrating the metal plate 12, thus avoiding corrosion problems caused by the metal plate 12 being exposed at the first mounting holes 15. Meanwhile, the fiber-reinforced resin frame 13 is beneficial in improving the overall thickness and tensile shear strength of the mounting position and provides sufficient mounting stability.

[0055] Multiple first mounting holes 15 are formed on the outer circumference of the metal plate 12, uniformly distributing the gravitational force acting on the top and the impact force acting on the bottom of the metal plate 12.

[0056] Specifically, during installation, the connector is positioned to pass through the first mounting hole 15 and the second mounting hole 32, thereby securing the battery protection bottom plate 1 to the bottom of the battery pack 3. The connector is a rivet, screw, or bolt.

[0057] In different embodiments, the resins of the upper fiber-reinforced resin layer 11, the fiber-reinforced resin frame 13, and the lower fiber-reinforced resin layer 14 are each independently selected from thermosetting materials and / or thermoplastic materials. Examples, but not limited to, include epoxy resins, phenolic plastics, phenols, cyanate esters, imides (such as polyimides, bismaleimides (BMI), and polyetherimides), polypropylene, polyesters, benzoxazines, polybenzimidazoles, polybenzothiazoles, polyamides, polyamide-imides, polysulfones, polyethersulfones, polycarbonates, polyethylene terephthalates, polyether ketones (such as polyether ketone (PEK), polyether-ether-ketone (PEEK), or polyethylene-ketone-ketone (PEKK)), or combinations thereof.

[0058] In different embodiments, the fibers of the upper fiber-reinforced resin layer 11, the fiber-reinforced resin frame 13, and the lower fiber-reinforced resin layer 14 are independently selected from glass fibers, aramid fibers, carbon fibers, graphite fibers, boron fibers, or aromatic polyamide fibers, or mixtures thereof, respectively.

[0059] The upper fiber-reinforced resin layer 11, the fiber-reinforced resin frame 13, and the lower fiber-reinforced resin layer 14 may be embedded in the resin in the form of chopped fibers, long-cut fibers, nonwoven fabric, unidirectional reinforced fiber substrate, woven fabric, or the like.

[0060] In some embodiments, the upper fiber-reinforced resin layer 11, the fiber-reinforced resin frame 13, and the lower fiber-reinforced resin layer 14 are independently selected from glass fiber-reinforced polyamide resin components, glass fiber-reinforced polypropylene resin components, glass fiber-reinforced polyethylene resin components, glass fiber-reinforced polycarbonate resin components, or glass fiber-reinforced polystyrene resin components, respectively.

[0061] In some embodiments, the buffer region 4 is filled with a buffer layer 2. The buffer layer 2 is made from a honeycomb material or a rigid foam material.

[0062] The honeycomb material or rigid foam material can absorb the crush deformation space of the battery protection bottom plate 1 under the action of a strong external impact, buffer and absorb some of the energy of the strong external impact, prevent the compressive deformation of the battery protection bottom plate 1 from impacting the battery core inside the battery pack 3, and further protect the battery pack 3.

[0063] In some embodiments, the honeycomb material is selected from polypropylene (PP) honeycomb material or aluminum honeycomb material. The rigid foam material is selected from polyurethane (PU) rigid foam material, polyethylene terephthalate (PET) rigid foam material, polymethacrylimide (PMI) rigid foam material, polyvinyl chloride (PVC) rigid foam material, polyethylene terephthalate (PET) rigid foam material, microcellular polypropylene (MPP) rigid foam material, polylactic acid (PLA) rigid foam material, polyimide (PI) rigid foam material, or expanded thermoplastic polyurethane (EPTU) foam material.

[0064] In some embodiments, the metal plate 12 is selected from iron and its alloys, aluminum and its alloys, magnesium and its alloys, copper and its alloys, titanium and its alloys, and nickel and its alloys.

[0065] In some embodiments, the metal plate 12 is a steel plate. A zinc coating, a zinc-iron alloy coating, or an electrophoretic coating protective layer is applied to the outer surface of the steel plate.

[0066] Compared to other metal materials, steel sheet is used as the metal sheet 12 and has good tensile strength and elongation at break, can meet the requirements for impact resistance, and is beneficial in improving the protective effect on the battery pack 3.

[0067] The zinc coating, zinc-iron alloy coating, or electrophoretic coating protective layer is placed on the outer surface of the steel sheet and is configured to improve the corrosion resistance of the steel sheet. When the upper fiber-reinforced resin layer 11 or the lower fiber-reinforced resin layer 14 is damaged, the galvanic effect realized by the zinc coating or zinc-iron alloy coating and the steel sheet causes the zinc coating or zinc-iron alloy coating to corrode before the steel sheet, thereby providing a protective effect against the steel sheet. The electrophoretic coating protective layer has good adhesion and can effectively isolate the steel sheet from the external environment.

[0068] Another embodiment of the present disclosure discloses a vehicle 100 including the composite protective structure 10 for the battery pack described above, as shown in Figure 7.

[0069] This disclosure is further described below through embodiments. [Table 1]

[0070] Embodiment 1 This embodiment is used to illustrate a composite protective structure for a battery pack disclosed herein, and includes a battery pack, a buffer layer, and a battery protective bottom plate. The battery protective bottom plate includes a metal plate, an upper fiber-reinforced resin layer, a fiber-reinforced resin frame, and a lower fiber-reinforced resin layer. The metal plate is a galvanized steel plate. The metal plate is located between the upper fiber-reinforced resin layer and the lower fiber-reinforced resin layer. The metal plate is located inside the fiber-reinforced resin frame. The upper surface of the fiber-reinforced resin frame and the upper fiber-reinforced resin layer are integrally connected. The bottom surface of the fiber-reinforced resin frame and the lower fiber-reinforced resin layer are integrally connected. The battery protective bottom plate is positioned below the battery pack. A buffer region is formed between the battery pack and the battery protective bottom plate. The buffer region is filled with a buffer layer. A plurality of first mounting holes are formed at overlapping locations of the upper fiber-reinforced resin layer, the fiber-reinforced resin frame, and the lower fiber-reinforced resin layer. Multiple second mounting holes are formed in the bottom frame of the battery pack to correspond to the positions of the first mounting holes. The first and second mounting holes are connected by rivets.

[0071] The thickness d of the metal plate is 1.2 mm, the tensile strength σ of the metal plate is 780 MPa, the elongation at break ε of the metal plate is 15%, and the height h of the buffer zone is 12 mm.

[0072] Embodiments 2-25 Embodiments 2-25 are used to illustrate the composite protective structures for battery packs disclosed herein and include most of the structures of Embodiment 1. The difference is that steel plates and the height of the buffer area are employed, as provided in Embodiments 2-25 of Table 1.

[0073] Comparative Examples 1-3 Comparative Examples 1-3 are used to illustrate and compare the composite protective structures for battery packs disclosed herein and include most of the structures of Embodiment 1. The difference lies in the use of steel plates and the height of the buffer area, as provided in Comparative Examples 1-3 of Table 1.

[0074] Performance testing The following performance tests were performed on the composite protective structures for battery packs provided in the embodiments and comparative examples described above.

[0075] A sphere was used as an impactor to strike the battery protection bottom plate of a composite protective structure for a battery pack, simulating the operating conditions under which the entire bottom of a vehicle is struck by a foreign object. The sphere was defined as having a diameter of 25 mm and a gravity of 10 kg. The impact energy was 300 J, and the impact velocity was 8.5 m / s. Five impacts were applied to the center point of the battery protection bottom plate and four points around the center point.

[0076] The amount of concave deformation of the battery pack tray was measured at various impact points. The impact point with the maximum concave deformation was recorded as the amount of concave deformation of the battery pack tray. Generally, the amount of indentation after an impact with an energy of 300 J is required to be 3 mm or less.

[0077] The system recorded whether the battery protection base plate was damaged after the impact.

[0078] The obtained test results are recorded in Table 2. [Table 2]

[0079] From the test results in Table 2, it can be seen that the thickness d of the metal plate, the tensile strength σ of the metal plate, the elongation at break ε of the metal plate, and the height h of the buffer region in the composite protective structure for battery packs are correlated with each other.

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[0080] The foregoing describes only preferred embodiments of the Disclosure and is not intended to limit the Disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the Disclosure shall remain within the scope of the protections of the Disclosure. [Explanation of Symbols]

[0081] 100 vehicles 10. Composite protective structure for battery pack 1 Battery protection bottom plate 11 Upper fiber-reinforced resin layer 12 metal plate 13 Fiber-reinforced resin frame 14 Lower fiber-reinforced resin layer 15 First mounting hole 2 Buffer layer 3 Battery pack 31 trays 32 Second mounting hole 4 Buffer area

Claims

1. A composite protective structure (10) for a battery pack comprising a battery pack (3) and a battery protective bottom plate (1), wherein the battery protective bottom plate (1) comprises a metal plate (12) which is a steel plate, the battery protective bottom plate (1) is positioned below the battery pack (3), and a buffer region (4) filled with a buffer layer (2) is formed between the battery pack (3) and the battery protective bottom plate (1), and the buffer region (4) and the metal plate (12) satisfy the following conditions, [Math 1] Here, d is the thickness (mm) of the metal plate (12), σ is the tensile strength (MPa) of the metal plate (12), ε is the elongation at break (dimensionless) of the metal plate (12), and h is the height (mm) of the buffer region (4). The battery protection bottom plate (1) further comprises an upper fiber-reinforced resin layer (11), a fiber-reinforced resin frame (13), and a lower fiber-reinforced resin layer (14). The metal plate (12) is located between the upper fiber-reinforced resin layer (11) and the lower fiber-reinforced resin layer (14). The metal plate (12) is located inside the fiber-reinforced resin frame (13). The upper surface of the fiber-reinforced resin frame (13) and the upper fiber-reinforced resin layer (11) are integrally connected, and the bottom surface of the fiber-reinforced resin frame (13) and the lower fiber-reinforced resin layer (14) are integrally connected. This is a composite protection structure (10) for a battery pack.

2. The buffer region (4) and the metal plate (12) satisfy the following conditions: [Math 2] , the composite protective structure for a battery pack (10) according to claim 1.

3. The composite protective structure (10) for a battery pack according to claim 1, wherein the thickness d of the metal plate (12) is 0.7 to 1.5 mm.

4. The composite protective structure (10) for a battery pack according to claim 1, wherein the tensile strength σ of the metal plate (12) is 590 to 1180 MPa.

5. The composite protective structure (10) for a battery pack according to claim 1, wherein the elongation ε at break of the metal plate (12) is 0.05 to 0.

2.

6. The composite protective structure (10) for a battery pack according to claim 1, wherein the height h of the buffer region (4) is 4 to 12 mm.

7. The upper fiber-reinforced resin layer (11), the metal plate (12), and the lower fiber-reinforced resin layer (14) all have a rectangular sheet-like structure. The composite protective structure (10) for a battery pack according to claim 1, wherein the fiber-reinforced resin frame (13) has a sheet-like rectangular frame structure.

8. A composite protective structure (10) for a battery pack according to claim 1, wherein a plurality of first mounting holes (15) are formed at intervals on the inside of the edge of the battery protective bottom plate (1), the first mounting holes (15) pass through the upper fiber-reinforced resin layer (11), the fiber-reinforced resin frame (13), and the lower fiber-reinforced resin layer (14) in order, and a plurality of second mounting holes (32) are formed in the bottom frame of the battery pack (3) so as to correspond to the positions of the first mounting holes (15), and a connector passes through the space between the first mounting holes (15) and the second mounting holes (32).

9. The composite protective structure (10) for a battery pack according to claim 1, wherein the upper fiber-reinforced resin layer (11), the fiber-reinforced resin frame (13), and the lower fiber-reinforced resin layer (14) are each independently selected from glass fiber-reinforced polyamide resin components, glass fiber-reinforced polypropylene resin components, glass fiber-reinforced polyethylene resin components, glass fiber-reinforced polycarbonate resin components, or glass fiber-reinforced polystyrene resin components.

10. The buffer region (4) is provided with the buffer layer (2), which is made from a honeycomb material or a rigid foam material, in the composite protective structure (10) for a battery pack according to claim 1.

11. The composite protective structure (10) for a battery pack according to claim 1, wherein a zinc coating, a zinc-iron alloy coating, or an electrophoretic coating protective layer is disposed on the outer surface of the steel plate.

12. A vehicle (100) comprising a composite protective structure (10) for a battery pack according to any one of claims 1 to 11.

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