A rocker panel and vehicle

Abstract

The utility model embodiment provides a kind of bottom guard plate and vehicle, belong to battery pack bottom guard plate technical field.The bottom guard plate includes at least one rigid support layer and at least one lower buffer layer, the rigid support layer has the first side away from battery pack and the second side close to the battery pack, the lower buffer layer is fiberless resin layer, the lower buffer layer is arranged at the first side of the rigid support layer away from the battery pack, wherein the elongation at break of the lower buffer layer is 100%~300%.The bottom guard plate of the utility model embodiment has excellent impact resistance, can effectively protect battery pack when impacted;And the lightweight of battery pack bottom guard plate can be realized, improve the cruising range of new energy vehicle.

Description

Technical Field

[0001] This utility model belongs to the technical field of battery pack bottom protection plate, specifically relating to a bottom protection plate and a vehicle. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the safety of battery components, as core components, is particularly important for vehicle safety. Since the battery pack is located at the bottom of the vehicle, it is susceptible to strong external impacts such as stones, uneven ground surfaces, or car accidents during driving, which can damage the battery pack and lead to safety incidents. Therefore, many OEMs install underbody protection plates to protect the battery pack and improve vehicle safety.

[0003] Currently, the mainstream method for underbody protection plates is to use high-strength metal sheets, such as steel plates. However, due to the high density of steel plates, the weight of the car is significantly increased, which will affect the driving range of new energy vehicles. Moreover, high-strength metal sheets generally have poor impact resistance and are prone to breakage when subjected to impact, which can easily penetrate the battery pack and damage the battery cells. In addition, the conductivity of the metal sheets also affects the safety of the car.

[0004] Therefore, there is an urgent need to develop a lightweight battery pack bottom protector that can effectively protect the safety of the battery pack and achieve the goal of lightweighting the battery pack bottom protector. Utility Model Content

[0005] This invention aims to at least partially solve one of the technical problems in the related art. To this end, embodiments of this invention propose a bottom guard plate and a vehicle, which achieves excellent impact resistance, effectively protects the battery pack, and achieves lightweighting of the battery pack bottom guard plate.

[0006] This utility model provides a bottom protection plate, which includes at least one rigid support layer and at least one lower buffer layer. The rigid support layer has a first side away from the battery pack and a second side close to the battery pack. The lower buffer layer is a fiber-free resin layer and is disposed on the first side of the rigid support layer away from the battery pack. The elongation at break of the lower buffer layer is 100% to 300%.

[0007] The advantages and technical effects of the battery pack bottom protective plate of this utility model embodiment are as follows:

[0008] Compared to steel plate bottom protectors in related technologies, the bottom protector of this embodiment includes at least one rigid support layer and at least one lower buffer layer. The lower buffer layer is a fiber-free resin layer with an elongation at break of 100% to 300%, thus exhibiting good impact resistance. Furthermore, its density is significantly lower than that of steel plate bottom protectors, resulting in a lighter weight for the same volume. Therefore, the bottom protector of this embodiment possesses excellent impact resistance, effectively protecting the battery pack during impacts. It also achieves lightweighting of the battery pack bottom protector, improving the driving range of new energy vehicles.

[0009] In some embodiments, the tensile strength of the lower buffer layer is 30 MPa to 70 MPa;

[0010] And / or, the lower buffer layer includes at least one of the following: a fiber-free polyurethane resin layer, a fiber-free epoxy resin layer, a fiber-free vinyl resin layer, a fiber-free polyurethane modified epoxy resin layer, a fiber-free polyurethane modified vinyl resin layer, and a fiber-free epoxy modified vinyl resin layer.

[0011] And / or, the elastic modulus of the lower buffer layer in the direction perpendicular to the thickness of the lower buffer layer is 0.5 GPa to 3.0 GPa;

[0012] And / or, the density of the lower buffer layer is 1.0 g / cm³. 3 ~2.0 g / cm 3 .

[0013] Preferably, the lower buffer layer is a fiber-free polyurethane resin layer.

[0014] In some embodiments, the rigid support layer has a flexural modulus ≥80 GPa in the direction perpendicular to the thickness of the rigid support layer;

[0015] And / or, the rigid support layer includes at least one of a metal plate, a plastic plate, and a high-rigidity composite plate.

[0016] In some embodiments, the bottom cover further includes at least one upper buffer layer, the upper buffer layer comprising a fiber-free resin layer and / or a fiber-reinforced resin layer, the upper buffer layer being disposed on the second side of the rigid support layer near the battery pack.

[0017] In some embodiments, the upper buffer layer is a fiber-free resin layer, and the tensile strength of the upper buffer layer is 30MPa to 70MPa;

[0018] And / or, the elongation at break of the upper buffer layer is 100% to 300%;

[0019] And / or, the elastic modulus of the upper buffer layer in the direction perpendicular to the thickness of the upper buffer layer is 0.5 GPa to 3.0 GPa;

[0020] And / or, the density of the upper buffer layer is 1.0 g / cm³. 3 ~2.0 g / cm 3 .

[0021] In some embodiments, the upper buffer layer is a fiber-reinforced resin layer, which includes at least one of a fiber-reinforced polyurethane resin layer, a fiber-reinforced epoxy resin layer, a fiber-reinforced vinyl resin layer, a fiber-reinforced polyurethane-modified epoxy resin layer, a fiber-reinforced polyurethane-modified vinyl resin layer, and a fiber-reinforced epoxy-modified vinyl resin layer.

[0022] And / or, the flexural modulus of the fiber-reinforced resin layer in the direction perpendicular to the thickness of the fiber-reinforced resin layer is 0.5 GPa to 30 GPa;

[0023] And / or, the density of the fiber-reinforced resin layer is 1.5 g / cm³. 3 ~2.1g / cm 3 .

[0024] Secondly, this utility model provides a vehicle, which includes a battery pack and a bottom protection plate, wherein the bottom protection plate is the bottom protection plate described in the first aspect, and the second side of the bottom protection plate is opposite to the battery pack.

[0025] The advantages and technical effects of the vehicle according to this utility model embodiment are as follows:

[0026] Because of the underbody protection plate described in the first aspect, the vehicle of this utility model embodiment has all the advantages brought by the underbody protection plate described in the first aspect, which will not be repeated here. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a bottom protective plate according to an embodiment of the present utility model;

[0028] Figure 2 This is a schematic diagram of the structure of another bottom protective plate according to an embodiment of the present utility model;

[0029] Explanation of reference numerals in the attached figures:

[0030] 1-Bottom protective plate; 11-Rigid support layer; 12-Lower buffer layer; 13-Upper buffer layer; 2-Battery pack. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In a first aspect, this utility model embodiment provides a bottom protective plate 1, such as... Figure 1 and Figure 2 As shown, it includes at least one rigid support layer 11 and at least one lower buffer layer 12. The rigid support layer 11 has a first side away from the battery pack 2 and a second side close to the battery pack 2. The lower buffer layer 12 is a fiber-free resin layer (meaning it is composed of pure resin). The lower buffer layer 12 is located on the first side of the rigid support layer 11 away from the battery pack 2, wherein the elongation at break of the lower buffer layer 12 is 100% to 300%.

[0033] Compared to steel plate bottom protectors in related technologies, the bottom protector of this embodiment includes at least one rigid support layer and at least one lower buffer layer. The lower buffer layer is a fiber-free resin layer with a large elongation at break (e.g., 100%–300%), thus exhibiting good impact resistance. Furthermore, its density is significantly lower than that of steel plate bottom protectors, resulting in a reduced weight for the same volume. Therefore, the bottom protector of this embodiment possesses excellent impact resistance, effectively protecting the battery pack during impacts. It also achieves lightweighting of the battery pack bottom protector, improving the driving range of new energy vehicles.

[0034] Pure resin has a high elongation at break (e.g., 100-300%). When the lower buffer layer is impacted, the pure resin-based lower buffer layer experiences large compressive deformation, absorbs more energy, and transfers less impact energy to the rigid support layer. The rigid support layer is less prone to deformation and less likely to penetrate the battery pack, damaging the cells. However, if the resin material of the lower buffer layer is replaced with fiber-reinforced resin, the elongation at break of the fiber-reinforced resin, which is close to that of the pure resin, will decrease significantly. When the lower buffer layer is impacted, the compressive deformation is even smaller, less energy is absorbed, and more impact energy is directly transferred to the rigid support layer. The rigid support layer is more prone to deformation, allowing more energy to penetrate the battery pack and damage the cells.

[0035] The bottom protective plate of this utility model embodiment includes two parts: a lower buffer layer 12 and a rigid support layer 11. The lower buffer layer 12 has at least one layer, and the rigid support layer 11 also has at least one layer. Therefore, the structure of the bottom protective plate of this utility model embodiment can be a double-layer or multi-layer structure (e.g., 3 layers, 4 layers, 5 layers, 6 layers, etc.). The lower buffer layer 12 must be placed at the bottommost layer of the bottom protective plate 1, that is, the side that is first hit by the object impacting the battery pack during the impact process. This is to effectively resist the impact force and protect the battery pack. The rigid support layer 11 is set on the upper layer of the bottom protective plate 1.

[0036] In some embodiments, the tensile strength of the lower buffer layer is 30 MPa to 70 MPa, such as 30 MPa, 35 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, etc., and the elongation at break is 100% to 300%. When the tensile strength and elongation at break of the lower buffer layer are within the above ranges, the lower buffer layer composed of fiber-free resin has excellent impact resistance.

[0037] The lower buffer layer includes, but is not limited to, at least one of the following: a fiber-free polyurethane resin layer, a fiber-free epoxy resin layer, a fiber-free vinyl resin layer, a fiber-free polyurethane-modified epoxy resin layer, a fiber-free polyurethane-modified vinyl resin layer, and a fiber-free epoxy-modified vinyl resin layer. The tensile strength of the fiber-free resin layers listed above is 30 MPa to 70 MPa, and the elongation at break is 100% to 300%, forming a lower buffer layer with excellent impact resistance.

[0038] Preferably, the lower buffer layer is a fiber-free polyurethane resin layer. Compared to the other fiber-free resin layers listed above, the lower buffer layer composed of a fiber-free polyurethane resin layer has better impact resistance.

[0039] More preferably, the raw materials for preparing the fiber-free polyurethane resin layer include an isocyanate component and an isocyanate reactive component; the isocyanate reactive component includes a polyol component, a chain extender, and optional additives; the polyol component includes a polyol with a linear structure and an average functionality of 2-3. Compared with ordinary polyurethane resin layers in related technologies, the fiber-free polyurethane resin layer described above has superior impact resistance, scratch resistance, and puncture resistance, which is more conducive to improving the performance of the underlying buffer layer.

[0040] In some embodiments, the elastic modulus of the lower buffer layer in the direction perpendicular to its thickness is 0.5 GPa to 3.0 GPa, for example, 0.5 GPa, 1.0 GPa, 1.5 GPa, 2.0 GPa, 2.5 GPa, 3.0 GPa, etc. Meeting these conditions is beneficial for improving the impact resistance of the bottom guard plate.

[0041] In some embodiments, the density of the lower buffer layer is 1.0 g / cm³. 3 ~2.0 g / cm 3 For example, 1.0 g / cm³ 3 1.2g / cm 3 1.4g / cm 3 1.6g / cm 3 1.8g / cm 3 2.0g / cm 3 Meeting the above conditions is beneficial for achieving lightweight bottom protection plates.

[0042] The rigid support layer includes, but is not limited to, at least one of metal plates, plastic plates, and high-rigidity composite plates. The metal plate may include, but is not limited to, at least one of steel plates, iron plates, aluminum plates, titanium plates, etc.; the surface of the metal plate may be uncoated or coated, and the coating may be, for example, a galvanized layer, a galvanized iron alloy layer, or an electrophoretic paint protective layer; the metal plate may be an untreated metal plate or a pretreated metal plate, and the pretreatment may include sandblasting, shot blasting followed by degreasing and dust removal, or plasma treatment. The plastic plate may include, but is not limited to, at least one of polyetheretherketone (PEEK) plastic plates, polypropylene (PP) plastic plates, polyethylene (PE) plastic plates, polyamide (PA, nylon) plastic plates, polycarbonate (PC) plastic plates, acrylonitrile-butadiene-styrene copolymer (ABS) plastic plates, and polyvinyl chloride (PVC) plastic plates. The high-rigidity composite plate may include, but is not limited to, a composite plate composed of at least two of aramid fibers, high molecular weight polyethylene fibers, and basalt fibers.

[0043] In some embodiments, the rigid support layer has a flexural modulus ≥ 80 GPa in the direction perpendicular to its thickness, such as 80 GPa, 90 GPa, 100 GPa, 110 GPa, 120 GPa, 140 GPa, 160 GPa, 180 GPa, 200 GPa, 220 GPa, 240 GPa, 280 GPa, 300 GPa, etc. Meeting these conditions helps the rigid support layer to resist bending or deformation under stress, better maintain its original shape, better absorb and disperse impact forces, and improve safety.

[0044] In some embodiments, the bottom protective plate may further include at least one upper buffer layer 13, which includes a fiber-free resin layer and / or fiber-reinforced resin. The upper buffer layer is disposed on the second side of the rigid support layer 11 near the battery pack 2. The lower buffer layer 12, the rigid support layer 11, and the upper buffer layer 13 can form a sandwich structure. The upper buffer layer 13 is disposed between the rigid support layer 11 and the battery pack 2, which can play a secondary buffering role and further improve the impact resistance of the bottom protective plate.

[0045] In some embodiments, the upper buffer layer is a fiber-free resin layer, and the tensile strength of the upper buffer layer is 30 MPa to 70 MPa, for example, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, etc.; and / or, the elongation at break of the upper buffer layer is 100% to 300%, for example, 100%, 150%, 200%, 250%, 300%, etc.; and / or, the elastic modulus of the upper buffer layer in the direction perpendicular to the thickness of the upper buffer layer is 0.5 GPa to 3.0 GPa, for example, 0.5 GPa, 1.0 GPa, 1.5 GPa, 2.0 GPa, 2.5 GPa, 3.0 GPa, etc.; and / or, the density of the upper buffer layer is 1.0 g / cm³. 3 ~2.0 g / cm 3 For example, 1.0 g / cm³ 3 1.2g / cm 3 1.4g / cm 3 1.6g / cm 3 1.8g / cm 3 2.0g / cm 3 This helps improve the impact resistance of the upper buffer layer.

[0046] In some embodiments, the upper buffer layer is a fiber-reinforced resin layer, which includes at least one of a fiber-reinforced polyurethane resin layer, a fiber-reinforced epoxy resin layer, a fiber-reinforced vinyl resin layer, a fiber-reinforced polyurethane-modified epoxy resin layer, a fiber-reinforced polyurethane-modified vinyl resin layer, and a fiber-reinforced epoxy-modified vinyl resin layer. The upper buffer layer composed of the fiber-reinforced resin layers listed above possesses good impact resistance.

[0047] Preferably, the fiber-reinforced resin layer is a fiber-reinforced polyurethane resin layer. Compared to the other fiber-reinforced resin layers listed above, the upper buffer layer exhibits better impact resistance when it is a fiber-reinforced polyurethane resin layer. Although the impact resistance of the upper buffer layer composed of a fiber-reinforced resin layer is not as good as that of the upper buffer layer composed of a non-fiber resin layer, it still possesses good impact resistance.

[0048] More preferably, the raw materials for preparing the polyurethane resin in the fiber-reinforced polyurethane resin layer include an isocyanate component and an isocyanate reactive component; the isocyanate reactive component includes a polyol component, a chain extender, and optional additives; the polyol component includes a polyol with a linear structure and an average functionality of 2-3. Compared with ordinary polyurethane resin layers in related technologies, the above-described polyurethane resin layer has superior impact resistance, scratch resistance, and puncture resistance, which is more conducive to improving the performance of the upper buffer layer.

[0049] In some embodiments, based on the total mass of the fiber-reinforced resin layer as 100 wt.%, the resin content is 30 wt.% to 95 wt.%, for example, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, 95 wt.%, etc.; the fiber content is 5 wt.% to 70 wt.%, for example, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, etc. Meeting the above conditions is beneficial for the battery pack bottom protection plate to achieve good impact resistance, strength, and rigidity.

[0050] In some embodiments, the upper buffer layer is a fiber-reinforced resin layer, and the flexural modulus of the fiber-reinforced resin layer in the direction perpendicular to its thickness is 0.5 GPa to 30 GPa, for example, 0.5 GPa, 1 GPa, 1.5 GPa, 2 GPa, 2.5 GPa, 3 GPa, etc. Meeting the above conditions is beneficial to improving the impact resistance of the bottom guard plate.

[0051] In some embodiments, the upper buffer layer is a fiber-reinforced resin layer with a density of 1.1 g / cm³. 3 ~1.9 g / cm 3 For example, 1.1 g / cm 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 1.9g / cm 3 Meeting the above conditions helps reduce the weight of the bottom guard plate itself.

[0052] In some embodiments, the total thickness of the bottom protective plate is 1.8mm to 8.0mm, for example, 1.8mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, etc. A thickness within this range effectively protects the battery pack while reducing the weight of the bottom protective plate itself.

[0053] Optionally, the thickness of the lower buffer layer is 1.4 mm to 7.6 mm, such as 1.4 mm, 1.6 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.6 mm, etc.; the thickness of the rigid support layer is 0.4 mm to 2.0 mm, such as 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, etc.

[0054] Optionally, when the bottom protective plate has the upper buffer layer, the thickness of the upper buffer layer is ≥0.2mm, preferably 0.2mm to 0.8mm, such as 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.

[0055] It is understood that the bottom protective plate of this utility model embodiment may also have other material layers, such as an elastomer layer, a foam layer, an air layer, etc., and these other material layers may be disposed inside the rigid support layer. When the bottom protective plate has a lower buffer layer and a rigid support layer, but no upper buffer layer, the other material layers may be disposed on the first side of the rigid support layer near the battery pack. When the bottom protective plate has a lower buffer layer, a rigid support layer, and an upper buffer layer, the other material layers may be disposed on the side of the upper buffer layer near the battery pack.

[0056] The bottom protective plate of this utility model embodiment can be integrally formed by the following curing and molding processes: for example, hand lay-up molding, spray molding, resin transfer molding, bag pressing, vacuum bag pressing, autoclave molding, hydraulic autoclave molding, thermal expansion molding, molding material production, SMC molding material injection, casting, pultrusion, STM molding, cold die stamping, injection molding, or extrusion molding, etc.

[0057] Secondly, this utility model provides a vehicle, which includes a battery pack and a bottom protection plate, wherein the bottom protection plate is the bottom protection plate described in the first aspect, and the second side of the bottom protection plate is opposite to the battery pack.

[0058] Because of the underbody protection plate described in the first aspect, the vehicle of this utility model embodiment has all the advantages brought by the underbody protection plate described in the first aspect, which will not be repeated here.

[0059] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0060] Specific experimental methods are not specified in the following examples; they are generally performed under standard conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages and parts are by weight.

[0061] Example 1

[0062] The bottom protective plate 1 of this embodiment has a three-layer structure. From the direction away from the battery pack 2 to the direction closer to the battery pack 2, the bottom buffer layer 12, the rigid support layer 11 and the upper buffer layer 13 are stacked in sequence. The total thickness of the bottom protective plate is 2.8mm.

[0063] The lower buffer layer is a fiber-free polyurethane resin layer with a thickness of 1.5 mm.

[0064] The rigid support layer is made of steel plate, and the thickness of the rigid support layer is 0.8mm;

[0065] The upper buffer layer is a glass fiber reinforced polyurethane resin layer with a thickness of 0.5 mm.

[0066] The method for preparing the bottom protective plate of the battery pack in this embodiment includes the following steps:

[0067] 1. Analyze the product's digital model and output the material cutting diagram.

[0068] Provide fiberglass cloth (EBT650, Jiangsu Jiuding Industrial Materials Co., Ltd.); then use automatic cutting equipment to cut the fiberglass cloth.

[0069] In addition, the steel plate is pretreated by sandblasting, shot blasting, degreasing and dust removal to obtain the pretreated steel plate.

[0070] In addition, isocyanate components and isocyanate reactive components are provided:

[0071] Polymerized MDI (NCO content 31.2 wt.%, Wanhua Chemical), WANNATEMDI-100 (NCO content 33.5 wt.%, Wanhua Chemical), and diethylene glycol modified MDI (NCO content 21.0 wt.%, Wanhua Chemical) were weighed in a mass ratio of 20:30:50 and mechanically stirred at 2000 rpm for 30 min at 25 °C to prepare the isocyanate component.

[0072] Weigh out polytetrahydrofuran polyol (brand name: PTMEG2000, weight average molecular weight 2200, hydroxyl value 50mgKOH / g, Hyosung Chemical), polyether polyol (brand name: F3156, weight average molecular weight 3000, glycerol initiator, hydroxyl value 57mgKOH / g, Wanhua Chemical), chain extender ethylene glycol, and flame retardant tri(chloroisopropyl) phosphate (TCPP) in a mass ratio of 40:10:30:20. Mix the materials uniformly at 5000 rpm under mechanical stirring at 25°C to obtain the isocyanate reactive component.

[0073] 2. Place the pretreated steel plate on top of the cut fiberglass cloth, transfer both to the preforming mold simultaneously, and fix them together with adhesive to obtain the preform.

[0074] 3. Provide a dedicated mold for the high-pressure resin transfer molding (HP-RTM) process. Clean the HP-RTM mold and spray a release agent on its surface. Transfer the preform into the HP-RTM mold, install and tighten the bolts, then evacuate the HP-RTM mold. Preheat the HP-RTM mold to 120°C and lock it, controlling the mold cavity vacuum to -0.98 Bar. Using a high-pressure injection molding machine, mix and inject the isocyanate component and isocyanate reactive component at a mass ratio of 1:1.6 into both sides of the preform in the HP-RTM mold through the injection nozzle. The injection pressure is 15 MPa. After injection, hold the pressure for 3 minutes for hot pressing and then open the mold.

[0075] 4. Post-processing: Using cutting equipment, cut off the waste edges of the bottom cover plate according to the requirements of the battery pack bottom cover plate drawing, and make holes in the bottom cover plate.

[0076] In this process, on the side of the steel plate with fiberglass cloth, the isocyanate component and the isocyanate reactive component react to form polyurethane resin, which together with the fiberglass cloth constitutes the upper buffer layer. On the side of the steel plate away from the fiberglass cloth, the isocyanate component and the isocyanate reactive component react to form polyurethane resin (tensile strength of 45 MPa and elongation at break of 180%), which forms the lower buffer layer.

[0077] The elastic modulus of the lower buffer layer perpendicular to its thickness is 0.9 GPa. The density of the lower buffer layer is 1.25 g / cm³. 3 .

[0078] The flexural modulus of the rigid support layer in the direction perpendicular to its thickness is 200 GPa.

[0079] The elastic modulus of the upper buffer layer perpendicular to its thickness is 23 GPa. The density of the upper buffer layer is 1.9 g / cm³. 3 .

[0080] Example 2

[0081] In this embodiment, the thickness of the lower buffer layer in the bottom protective plate is 2mm, and the total thickness of the bottom protective plate is 3.3mm.

[0082] Example 3

[0083] In this embodiment, the thickness of the lower buffer layer in the bottom protective plate is 2.5 mm, and the total thickness of the bottom protective plate is 3.8 mm.

[0084] Example 4

[0085] The bottom protective plate of this embodiment has a two-layer structure. From the direction away from the battery pack to the direction closer to the battery pack, there are a lower buffer layer and a rigid support layer stacked in sequence. The total thickness of the bottom protective plate is 2.3mm.

[0086] The lower buffer layer is a fiber-free polyurethane resin layer with a thickness of 1.5 mm.

[0087] The rigid support layer is made of steel plate and has a thickness of 0.8 mm.

[0088] The method for preparing the bottom protective plate of the battery pack in this embodiment includes the following steps:

[0089] 1. Analyze the product's digital model and output the material cutting diagram.

[0090] In addition, the steel plate is pretreated by sandblasting, shot blasting, degreasing and dust removal to obtain the pretreated steel plate.

[0091] In addition, isocyanate components and isocyanate reactive components are provided: the same as in Example 1.

[0092] 2. Provide a dedicated mold for the high-pressure resin transfer molding (HP-RTM) process. Clean the HP-RTM mold and spray a release agent on its surface. Transfer the pretreated steel plate into the HP-RTM mold, install bolts and tighten the mold. Then, evacuate the HP-RTM mold and preheat it to 120°C before locking it. Control the mold cavity vacuum to -0.98 Bar. Using a high-pressure injection machine, mix and inject the isocyanate component and isocyanate reactive component at a mass ratio of 1:1.6 into one side of the steel plate in the HP-RTM mold through the injection nozzle. The injection pressure is 15 MPa. After injection, hold the pressure for 3 minutes for hot pressing and then open the mold.

[0093] 4. Post-processing: Using cutting equipment, cut off the waste edges of the bottom cover plate according to the requirements of the battery pack bottom cover plate drawing, and make holes in the bottom cover plate.

[0094] The isocyanate component and the isocyanate reactive component react to form a polyurethane resin (tensile strength of 45 MPa and elongation at break of 180%), which forms the lower buffer layer.

[0095] The elastic modulus of the lower buffer layer in the direction perpendicular to its thickness is 0.9 GPa. The density of the lower buffer layer is 1.25 g / cm³. 3 .

[0096] The flexural modulus of the rigid support layer in the direction perpendicular to its thickness is 200 GPa.

[0097] Example 5

[0098] The bottom protective plate 1 of this embodiment has a three-layer structure. From the direction away from the battery pack 2 to the direction closer to the battery pack 2, the bottom buffer layer 12, the rigid support layer 11 and the upper buffer layer 13 are stacked in sequence. The total thickness of the bottom protective plate is 2.8mm.

[0099] The lower buffer layer is a fiber-free polyurethane resin layer with a thickness of 1.5 mm.

[0100] The rigid support layer is made of steel plate, and the thickness of the rigid support layer is 0.8mm;

[0101] The upper buffer layer is a fiber-free polyurethane resin layer with a thickness of 0.5 mm.

[0102] The method for preparing the bottom protective plate in this embodiment includes the following steps:

[0103] 1. Analyze the product's digital model and output the material cutting diagram.

[0104] In addition, the steel plate is pretreated by sandblasting, shot blasting, degreasing and dust removal to obtain the pretreated steel plate.

[0105] In addition, isocyanate components and isocyanate reactive components are provided: the same as in Example 1.

[0106] 2. Provide a dedicated mold for the high-pressure resin transfer molding (HP-RTM) process. Clean the HP-RTM mold and spray a release agent on its surface. Transfer the pretreated steel plate into the HP-RTM mold, install bolts and tighten the HP-RTM mold. Then, evacuate the HP-RTM mold and preheat it to 120°C before locking the mold. Control the mold cavity vacuum to -0.98 Bar. Using a high-pressure injection molding machine, mix and inject the isocyanate component and the isocyanate reactive component at a mass ratio of 1:1.6 into one side of the steel plate in the HP-RTM mold through the injection nozzle. The injection pressure is 15 MPa. After injection, hold the pressure for 3 minutes for hot pressing and then open the mold to obtain the composite material of this embodiment.

[0107] The isocyanate component and the isocyanate reactive component react to form a polyurethane resin (tensile strength of 45 MPa and elongation at break of 180%), which forms a lower buffer layer and an upper buffer layer.

[0108] The elastic modulus of the lower buffer layer in the direction perpendicular to its thickness is 0.9 GPa. The density of the lower buffer layer is 1.25 g / cm³. 3 .

[0109] The flexural modulus of the rigid support layer in the direction perpendicular to its thickness is 200 GPa.

[0110] The elastic modulus of the upper buffer layer in the direction perpendicular to its thickness is 0.9 GPa. The density of the upper buffer layer is 1.25 g / cm³. 3 .

[0111] Comparative Example 1

[0112] The bottom protective plate 1 of this comparative example has a three-layer structure, which consists of a lower buffer layer, a rigid support layer and an upper buffer layer stacked sequentially from the direction away from the battery pack to the direction closer to the battery pack. The total thickness of the bottom protective plate is 2.8 mm.

[0113] The lower buffer layer is a glass fiber reinforced resin layer, which is composed of glass fiber and polyurethane resin. Based on the total mass of the lower buffer layer of 100 wt.%, the content of glass fiber is 66 wt.% and the content of polyurethane resin is 34 wt.%. The thickness of the lower buffer layer is 1.5 mm.

[0114] The rigid support layer is made of steel plate, and the thickness of the rigid support layer is 0.8mm;

[0115] The upper and lower buffer layers are made of the same material, and the lower buffer layer is 0.5mm thick.

[0116] The preparation method of the bottom protective plate in this comparative example includes the following steps:

[0117] 1. Analyze the product's digital model and output the material cutting diagram.

[0118] Provide fiberglass cloth (EBT650, Jiangsu Jiuding Industrial Materials Co., Ltd.); then use automatic cutting equipment to cut the fiberglass cloth.

[0119] In addition, the steel plate is pretreated by sandblasting, shot blasting, degreasing and dust removal to obtain the pretreated steel plate.

[0120] In addition, isocyanate components and isocyanate reactive components are provided:

[0121] Polymerized MDI (NCO content 31.2 wt.%, Wanhua Chemical), WANNATEMDI-100 (NCO content 33.5 wt.%, Wanhua Chemical), and diethylene glycol modified MDI (NCO content 21.0 wt.%, Wanhua Chemical) were weighed in a mass ratio of 20:30:50 and mechanically stirred at 2000 rpm for 30 min at 25 °C to prepare the isocyanate component.

[0122] Weigh out polytetrahydrofuran polyol (brand name: PTMEG2000, weight average molecular weight 2200, hydroxyl value 50mgKOH / g, Hyosung Chemical), polyether polyol (brand name: F3156, weight average molecular weight 3000, glycerol initiator, hydroxyl value 57mgKOH / g, Wanhua Chemical), chain extender ethylene glycol, and flame retardant tri(chloroisopropyl) phosphate (TCPP) in a mass ratio of 40:10:30:20. Mix the materials uniformly at 5000 rpm under mechanical stirring at 25°C to obtain the isocyanate reactive component.

[0123] 2. Place the pretreated steel plate on top of the cut fiberglass cloth, and then place another layer of cut fiberglass cloth on the pretreated steel plate. Transfer all three to the preforming mold simultaneously and fix them together with adhesive (but since the adhesive layer is relatively thin, it can be basically ignored) to obtain the preform.

[0124] 3. Provide a dedicated mold for the high-pressure resin transfer molding (HP-RTM) process. Clean the HP-RTM mold and spray a release agent on its surface. Transfer the preform into the HP-RTM mold, install and tighten the bolts, then evacuate the HP-RTM mold. Preheat the HP-RTM mold to 120°C and lock it, controlling the mold cavity vacuum to -0.98 Bar. Using a high-pressure injection molding machine, mix and inject the isocyanate component and isocyanate reactive component at a mass ratio of 1:1.6 into both sides of the preform in the HP-RTM mold through the injection nozzle. The injection pressure is 15 MPa. After injection, hold the pressure for 3 minutes for hot pressing and then open the mold.

[0125] The isocyanate component and the isocyanate reactive component react to form a polyurethane resin (tensile strength of 45 MPa and elongation at break of 180%). The polyurethane resin and the glass fiber cloth together form the upper and lower buffer layers.

[0126] The elastic modulus of the lower buffer layer in the direction perpendicular to its thickness is 23 GPa. The density of the lower buffer layer is 1.9 g / cm³. 3 .

[0127] The flexural modulus of the rigid support layer in the direction perpendicular to its thickness is 200 GPa.

[0128] The elastic modulus of the upper buffer layer in the direction perpendicular to its thickness is 23 GPa. The density of the upper buffer layer is 1.9 g / cm³. 3 .

[0129] Comparative Example 2

[0130] The bottom protective plate of this comparative example is the same as that of Comparative Example 1, except that the thickness of the lower buffer layer is 2 mm and the total thickness of the bottom protective plate is 3.3 mm.

[0131] Comparative Example 3

[0132] The bottom protective plate of this comparative example is the same as that of Comparative Example 1, except that the thickness of the lower buffer layer is 2.5 mm and the total thickness of the bottom protective plate is 3.8 mm.

[0133] Performance testing:

[0134] (1) Tensile strength test of fiber-free polyurethane resin layer. The tensile strength test standard is GB / T528-2009.

[0135] (2) The elongation at break of the fiberless polyurethane resin was tested. The standard for elongation at break is GB / T528-2009.

[0136] (3) The elastic modulus of the lower and upper buffer layers were tested respectively. The standard for elastic modulus testing is GB / T528-2009.

[0137] (4) The steel plate is subjected to bending modulus test. The standard for bending modulus test is GB / T9341-2008.

[0138] (5) Drop ball impact tests were conducted on the composite materials prepared in the above embodiments and comparative examples. The drop ball impact test was carried out using a self-made drop ball device. The ball was magnetically pulled up to a certain height and dropped vertically onto the surface of the composite material sample. The appearance of the composite material sample was then observed. If the composite material sample was not penetrated, the test was considered passed; if the composite material sample was penetrated, the test was considered failed. The diameter of the ball head was 25 mm, the length of the ball head was 50 mm, and the total weight of the ball was 60 kg. The actual area of ​​the composite material sample was 360 mm². The effective area of ​​the composite material sample after locking is 300 mm². In the 300mm and 500J impact tests, the ball was stretched to a height of 0.85m, and in the 600J impact test, the ball was stretched to a height of 1.02m.

[0139] (6) Weight test of bottom protection plate samples: Take the bottom protection plates of each embodiment and comparative example, and cut them into 300mm pieces. A bottom protection plate sample with an area of ​​300 mm² was prepared, and then the bottom protection plate sample was weighed to obtain the weight of the bottom protection plate sample.

[0140] Table 1. Key parameters and performance test results of the bottom protective plates in the above embodiments and comparative examples.

[0141]

[0142] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0143] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A bottom protective plate, characterized in that, It includes at least one rigid support layer and at least one lower buffer layer, the rigid support layer having a first side away from the battery pack and a second side close to the battery pack, the lower buffer layer being a fiber-free resin layer, the lower buffer layer being disposed on the first side of the rigid support layer away from the battery pack, wherein the elongation at break of the lower buffer layer is 100% to 300%.

2. The bottom protective plate according to claim 1, characterized in that, The tensile strength of the lower buffer layer is 30MPa to 70MPa; And / or, the lower buffer layer includes at least one of a fiber-free polyurethane resin layer, a fiber-free epoxy resin layer, a fiber-free vinyl resin layer, a fiber-free polyurethane modified epoxy resin layer, a fiber-free polyurethane modified vinyl resin layer, and a fiber-free epoxy modified vinyl resin layer. And / or, the elastic modulus of the lower buffer layer in the direction perpendicular to the thickness of the lower buffer layer is 0.5 GPa to 3.0 GPa; And / or, the density of the lower buffer layer is 1.0 g / cm³. 3 ~2.0 g / cm 3 .

3. The bottom protective plate according to claim 2, characterized in that, The lower buffer layer is a fiber-free polyurethane resin layer.

4. The bottom protective plate according to claim 1, characterized in that, The rigid support layer has a flexural modulus ≥80 GPa in the direction perpendicular to its thickness. And / or, the rigid support layer includes at least one of a metal plate, a plastic plate, and a high-rigidity composite plate.

5. The bottom protective plate according to claim 1, characterized in that, The bottom protective plate also includes at least one upper buffer layer, which comprises a fiber-free resin layer and / or a fiber-reinforced resin layer, and the upper buffer layer is disposed on the second side of the rigid support layer near the battery pack.

6. The bottom protective plate according to claim 5, characterized in that, The upper buffer layer is a fiber-free resin layer, and the tensile strength of the upper buffer layer is 30MPa to 70MPa; And / or, the elongation at break of the upper buffer layer is 100% to 300%; And / or, the elastic modulus of the upper buffer layer in the direction perpendicular to the thickness of the upper buffer layer is 0.5 GPa to 3.0 GPa; And / or, the density of the upper buffer layer is 1.0 g / cm³. 3 ~2.0 g / cm 3 .

7. The bottom protective plate according to claim 5, characterized in that, The upper buffer layer is a fiber-reinforced resin layer, which includes at least one of fiber-reinforced polyurethane resin layer, fiber-reinforced epoxy resin layer, fiber-reinforced vinyl resin layer, fiber-reinforced polyurethane modified epoxy resin layer, fiber-reinforced polyurethane modified vinyl resin layer, and fiber-reinforced epoxy modified vinyl resin layer. And / or, the flexural modulus of the fiber-reinforced resin layer in the direction perpendicular to the thickness of the fiber-reinforced resin layer is 0.5 GPa to 30 GPa; And / or, the density of the fiber-reinforced resin layer is 1.5 g / cm³. 3 ~2.1g / cm 3 .

8. The bottom protective plate according to claim 5, characterized in that, The thickness of the upper buffer layer is ≥0.2mm.

9. The bottom protective plate according to any one of claims 1 to 8, characterized in that, The total thickness of the bottom protective plate is 1.8mm to 8.0mm. The thickness of the lower buffer layer is 1.4 mm to 7.6 mm; the thickness of the rigid support layer is 0.4 mm to 2.0 mm.

10. A vehicle, characterized in that, It includes a battery pack and a bottom protection plate, wherein the bottom protection plate is the bottom protection plate according to any one of claims 1 to 9, and the second side of the bottom protection plate is opposite to the battery pack.

Images