Battery pack and electric vehicle

Abstract

This invention discloses a battery pack and an electric vehicle, relating to the field of battery technology. The pack includes a housing and multiple battery cells disposed within the housing. The housing includes a lower housing and a cover. The lower housing includes a frame and a bottom plate. The frame encloses a battery placement cavity. The frame includes a first surface near the battery cells and a second surface away from the battery cells. A mounting beam is provided on the second surface, and a first connecting hole is provided on the mounting beam. A bushing is disposed inside the first connecting hole. The width of the mounting beam along the second direction is 'a' mm, where the second direction is the width direction of the mounting beam. Along the first direction, the distance between the end face of the bushing near the cover and the surface of the cover away from the battery cells is 'd' mm, where a×d ranges from 2512 to 49680. The battery pack and electric vehicle of this invention ensure the structural strength of the connection between the mounting beam and the frame, while simultaneously improving the sealing performance of the connection between the cover and the housing.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery pack and an electric vehicle. Background Technology

[0002] Battery packs, as energy storage devices, are increasingly widely used in daily life and industry. A battery pack consists of a housing, on which a mounting beam is installed. This mounting beam is a key load-bearing structure connecting the battery pack to the vehicle chassis, directly affecting vehicle safety and battery life. The weight of the battery pack is transferred to the mounting beam, making it prone to breakage due to insufficient strength. Simultaneously, the mounting beam transmits vehicle vibrations to the sealing connection between the battery pack cover and the housing, thus affecting the sealing effect at this connection point. Summary of the Invention

[0003] In view of this, on the one hand, the present invention provides a battery pack that ensures the structural strength of the connection between the mounting beam and the frame, while improving the sealing performance of the connection between the cover and the body.

[0004] On the other hand, the present invention also provides an electric vehicle.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A battery pack includes a housing and a plurality of battery cells disposed within the housing. The housing includes a lower housing and a cover. The lower housing includes a frame and a base plate. The frame encloses a battery placement cavity. Along a first direction, the frame has a first opening and a second opening disposed opposite to each other. The first direction is the height direction of the frame. The cover seals the first opening, and the base plate seals the second opening. The battery cells are disposed on the surface of the base plate near the cover and are fixedly connected to the base plate. The first opening is sealed to the cover. The frame includes a first surface near the battery cell. A first surface and a second surface away from the battery cell, the second surface having at least one protruding mounting beam in a direction away from the battery cell, the mounting beam being fixedly connected to the second surface. Along a first direction, the mounting beam has an upper surface and a lower surface arranged opposite to each other, the upper surface being closer to the cover than the lower surface. The mounting beam has a first connecting hole that penetrates the upper and lower surfaces. A bushing is provided inside the first connecting hole for connecting fasteners for connecting the electric vehicle. The width of the mounting beam along a second direction is a mm, the second direction being the width direction of the mounting beam. Along the first direction, the distance between the end face of the bushing near the cover and the surface of the cover away from the battery cell is d mm, where a×d ranges from 2512 to 49680.

[0007] As can be seen from the above technical solution, the battery pack provided by the present invention, by setting the width of the mounting beam along the second direction to a mm, and setting the distance along the first direction between the end face of the bushing near the cover and the face of the cover away from the battery cell to d mm, and controlling the range of a×d within the above range, can not only ensure the structural strength of the connection position between the mounting beam and the frame, improve the reliability of the battery pack mounting, and reduce the risk of breakage at the connection position between the mounting beam and the frame, but also make it difficult for the vibration force on the vehicle body to be transmitted to the connection position between the cover and the frame through the mounting beam, reducing the probability of the sealing bolts at the connection position between the cover and the frame loosening, thereby reducing the risk of sealing failure at the connection position between the cover and the frame, and ensuring the sealing effect at the connection position between the cover and the lower box.

[0008] The present invention also provides an electric vehicle, including a chassis and a battery pack, wherein the battery pack is the aforementioned battery pack, and the battery pack is fixedly connected to the chassis via a mounting beam.

[0009] The electric vehicle of the present invention has the battery pack described above, and therefore has the advantages of the battery pack described above, which will not be repeated here. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a structural schematic diagram of a battery pack from one angle, provided in an embodiment of the present invention.

[0012] Figure 2 This is a structural schematic diagram of the battery pack provided in an embodiment of the present invention from another angle;

[0013] Figure 3 This is a structural schematic diagram of the battery pack from a third angle according to an embodiment of the present invention;

[0014] Figure 4 for Figure 3 A partially enlarged structural diagram of section A in the middle;

[0015] Figure 5 This is a schematic diagram of the structure of the box provided in an embodiment of the present invention;

[0016] Figure 6 This is a schematic diagram of the structure of the mounting beam provided in an embodiment of the present invention;

[0017] Figure 7 for Figure 6 A cross-sectional view of the BB position in the diagram;

[0018] Figure 8 This is a structural schematic diagram of the box lid at one angle provided in an embodiment of the present invention;

[0019] Figure 9 This is a structural schematic diagram of the box lid from another angle provided in an embodiment of the present invention;

[0020] Figure 10 A schematic diagram of the third angle of the box cover provided in an embodiment of the present invention;

[0021] Figure 11 for Figure 10 A magnified schematic diagram of a portion of the central C section;

[0022] Figure 12 This is a partial cross-sectional view of the box cover provided in an embodiment of the present invention;

[0023] Figure 13 A schematic diagram of a frame whose first end protrudes from both sides of the frame body, provided in an embodiment of the present invention;

[0024] Figure 14 A schematic diagram of the structure in an embodiment of the present invention showing that one side of the first end of the frame protrudes from the frame body;

[0025] Figure 15 A schematic diagram of the structure in another embodiment of the present invention, showing that one side of the first end of the frame protrudes from the frame body.

[0026] in:

[0027] 1. Box lid,

[0028] 101. First cover portion; 102. Second cover portion; 103. Third connecting hole.

[0029] 2. Lower box,

[0030] 201. First end; 202. Frame; 2021. First frame plate; 2022. Second frame plate; 2023. Third frame plate; 2024. Fourth frame plate; 203. Base plate; 204. Battery placement cavity.

[0031] 3. Mounted beams,

[0032] 301, Notch; 302, First connecting hole.

[0033] 4. Bushing,

[0034] 5. Positioning pin,

[0035] 6. Battery cells. Detailed Implementation

[0036] This invention discloses a battery pack that ensures the structural strength of the connection between the mounting beam and the frame, while improving the sealing performance of the connection between the cover and the body.

[0037] The present invention also discloses an electric vehicle.

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] A battery pack comprises a battery array consisting of multiple individual battery cells connected in series and / or parallel, a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (casing, brackets, etc.), and protective parts. These components are housed within a battery enclosure and sealed with a cover, forming a complete functional unit capable of directly outputting electrical energy. As a rechargeable battery, the battery pack is the power source for new energy vehicles.

[0040] A battery cell can store chemical energy and controllably convert it into electrical energy. In recyclable battery cells, the active materials can be reactivated by charging after discharge, allowing for continued use. A battery cell includes a casing and a battery cell housed within the casing.

[0041] The battery enclosure refers to a closed or semi-closed structure made of materials such as metal and plastic. It is the physical carrier of the battery pack, and its design and manufacturing must meet the safety, reliability and functionality requirements of the battery pack in different usage scenarios.

[0042] The battery enclosure provides installation space for the battery pack, BMS, cooling system, electrical connection components, etc., and through a reasonable structural design, fixes these components inside the battery enclosure, ensuring that they maintain a relatively stable position during battery pack operation and preventing damage or loosening of connections due to vibration, impact, or other factors. The battery enclosure of a battery pack generally consists of an upper enclosure and a lower enclosure. The lower enclosure typically has four side panels and a bottom plate. The four side panels can be integrally formed with the bottom plate or manufactured separately and fixedly connected. The battery enclosure can be cast from materials such as steel plate and aluminum alloy, or lightweight materials such as glass fiber reinforced composite materials and carbon fiber reinforced composite materials. The shape of the battery enclosure can be cylindrical, cuboid, cube, etc.

[0043] The battery casing, also known as the cover, is a sealed component that covers the cavity of the lower casing, encapsulating the battery pack within and isolating it from the outside environment to prevent external moisture and dust from affecting the battery module. The cover can be made of non-metallic materials, such as any polymer compound used as a raw material in plastics processing, commonly known as resin. Common resins include polyphenylene sulfide resin (PPS), polyphenylene oxide resin (PPO), and polypropylene resin (PP). Composite materials including reinforcing agents and resins can also be used; common reinforcing agents include glass fiber, carbon fiber, and graphite fiber. Metallic materials such as iron, aluminum, aluminum alloys, iron alloys, and stainless steel can also be used. Battery casing covers can come in various shapes, such as cuboids, depending on the specific requirements.

[0044] The battery pack's lower casing includes a base plate and a frame. The base plate is the main load-bearing component of the battery pack, typically referring to the structural member installed at the bottom of the pack, used to support and secure the battery pack, battery management system, cooling system, and other components inside. The base plate is located at the bottom of the casing frame, for example, by welding, riveting, or screwing. The base plate can be made of various materials, such as high-strength materials like aluminum alloy, steel, and stainless steel. The base plate can be rectangular, circular, polygonal, or a plate-like structure; its specific shape is not limited, and its dimensions are determined by the number and size of the battery cells housed in the battery pack.

[0045] The frame is the structural framework of the battery box, serving to support, protect, and connect components. The frame can be formed by splicing together multiple beams. In existing technologies, the frame typically includes four sub-frames, which are connected end-to-end to form an enclosed space. This enclosed space is sealed by a top cover and a bottom plate to form a cavity. The frame can be made of various materials, such as aluminum alloy, copper alloy, steel, and plastic. The frame can be rectangular, circular, polygonal, etc., with no specific limitations. The interior of the frame can be a solid structure or contain hollow cavities.

[0046] The base plate is the main load-bearing component of the battery pack. It typically refers to the structural component installed at the bottom of the battery pack, used to support and secure the internal components such as the battery pack, battery management system, and cooling system. The base plate is located at the bottom of the enclosure frame, for example, by welding, riveting, or screwing.

[0047] The mounting beam is a load-bearing structural component fixedly connected to the outside of the battery pack housing frame. It serves as the installation interface between the battery pack and the vehicle. The mounting beam can be welded or bolted to the outside of the battery pack frame, or it can be integrally formed with the frame. The mounting beam can be made of high-strength steel, aluminum alloy, or other materials.

[0048] A bushing is a precision component installed inside the mounting holes of a mount beam. When the battery pack is secured to the vehicle body with bolts, the bushing directly bears the clamping force of the bolts and evenly transmits the force to the mount beam, thus providing structural support. A bushing is a cylindrical or tubular mechanical part, typically made of metal or a metal-rubber composite, and its materials include steel, aluminum, and rubber.

[0049] Studies have found that in order to ensure the mounting strength of the battery pack and the vehicle body, a smaller mounting beam width is usually used. However, this can cause the vibration force on the vehicle body to be easily transmitted to the frame through the mounting beam, and then to the connection between the cover and the frame. This can cause the sealing bolts at the connection point to loosen, making it easy for the cover and the frame to fail to seal.

[0050] See Figures 1 to 15The battery pack of the present invention includes a housing and a plurality of battery cells 6 disposed within the housing. The housing includes a lower housing 2 and a housing cover 1. The lower housing 2 includes a frame 202 and a bottom plate 203. The frame 202 encloses a battery placement cavity 204. Along a first direction, the frame 202 has a first opening and a second opening disposed opposite to each other. The first direction is the height direction of the frame 202. The housing cover 1 seals the first opening, and the bottom plate 203 seals the second opening. The battery cells 6 are disposed on the surface of the bottom plate 203 near the housing cover 1 and are fixedly connected to the bottom plate 203. The first opening is sealed to the housing cover 1. The frame 202 includes a first surface near the battery cells 6 and a second surface away from the battery cells 6. At least one mounting beam 3 protrudes from the second surface in the direction away from the battery cells 6 and is fixedly connected to the second surface. Along the first direction, the mounting beam 3 has an upper surface and a lower surface disposed opposite to each other. The upper surface is closer to the housing cover 1 than the lower surface. The mounting beam 3 is provided with a first connecting hole 302, which penetrates the upper and lower surfaces. A bushing 4 is provided inside the first connecting hole 302, and the bushing 4 is used to connect fasteners for connecting the electric vehicle. The width of the mounting beam 3 along the second direction is a mm, where the second direction is the width direction of the mounting beam 3, i.e., the distance between the side of the mounting beam 3 away from the second surface and the second surface. Along the first direction, the distance between the bushing 4 near the end face of the cover 1 and the side of the cover 1 away from the battery cell 6 is d mm. The range of a×d is 2512-49680, specifically any value among 2512, 10000, 20000, 30000, 40000, and 49680, or a value between any two values. The preferred range of a×d is 7300-30200. The range of a×d is set within the aforementioned range to ensure the sealing effect at the connection between the cover 1 and the lower box 2, while also improving the structural reliability of the mounting beam 3 and reducing the risk of breakage at the connection between the mounting beam 3 and the frame 202. If the value of a×d is too small, the connection between the cover 1 and the lower box 2 is prone to sealing failure; if the value is too large, the connection between the mounting beam 3 and the frame 202 is prone to breakage, resulting in poor load-bearing strength.

[0051] The frame 202 and the base plate 203 can be an integral structure or separate structures. Multiple battery cells 6 are arranged within the battery placement cavity 204. A bushing 4 is installed inside the first connecting hole 302 to reduce the transmission of vibration at the connection point between the mounting beam 3 and the vehicle body. Decreasing parameter a mm reduces the cantilever length of the mounting beam 3, increasing its load-bearing strength. Simultaneously, due to the reduced cantilever length of the mounting beam 3, the path of vehicle body vibration transmitted through the mounting beam 3 to the lower housing 2 is shortened, making it easier for vibration to be transmitted to the connection point between the frame 202 and the housing cover 1, affecting the sealing performance of the connection. By limiting parameter a mm, the sealing performance of the connection point between the lower housing 2 and the housing cover 1 is ensured, guaranteeing the load-bearing strength. If the value of d mm is too small, the path length for vehicle body vibration transmitted through the mounting beam 3 to the connection point between the lower housing 2 and the cover 1 is short. Vibration can easily cause the connecting parts between the lower housing 2 and the cover 1 to loosen, thus affecting the sealing performance of the connection point. If the value of d mm is too large, the mounting stability of the mounting beam 3 is poor, and the mounting reliability of the battery pack is poor. By limiting the parameter d mm, the sealing performance of the connection point between the lower housing 2 and the cover 1, as well as the mounting reliability of the mounting beam 3, are ensured. To ensure connection reliability, multiple first connection holes 302 are provided, and a bushing 4 is provided in each first connection hole 302. An adhesive layer is provided on the bottom surface of the battery cell 6, and the bottom surface of the battery cell 6 is bonded to the base plate 203.

[0052] The battery pack of the present invention, by setting the width of the mounting beam 3 along the second direction to a mm, and setting the distance along the first direction between the end face of the bushing 4 near the cover 1 and the surface of the cover 1 away from the battery cell 6 to d mm, and controlling the range of a×d within the above-mentioned range, can not only ensure the structural strength of the connection position between the mounting beam 3 and the frame 202, improve the reliability of battery pack mounting, and reduce the risk of breakage at the connection position between the mounting beam 3 and the frame 202, but also make it less likely that the vibration force on the vehicle body will be transmitted to the connection position between the cover 1 and the frame 202 through the mounting beam 3, reducing the probability of loosening of the sealing bolts at the connection position between the cover 1 and the frame 202, thereby reducing the risk of sealing failure at the connection position between the cover 1 and the frame 202, and ensuring the sealing effect at the connection position between the cover 1 and the lower box 2.

[0053] Specifically, the cover 1 includes a first cover portion 101 and a second cover portion 102. The first cover portion 101 and the frame 202 at least partially overlap in orthographic projection along a first direction. The second cover portion 102 is correspondingly disposed with the battery placement cavity 204. The first cover portion 101 surrounds the second cover portion 102 and is used to connect with the frame 202. The second cover portion 102 is used to seal the first opening of the frame 202, thereby sealing the top of the battery placement cavity 204.

[0054] In one specific embodiment, the second cover portion 102 protrudes from the first cover portion 101 in a direction away from the battery cell 6, as shown in the figure. Figures 8 to 12 As shown, the height of the middle position of the lid 1 is higher than the height of the edge position. In this structure, because the second cover portion 102 is higher than the first cover portion 101 along the first direction, the second cover portion 102 and the first cover portion 101 need to be connected by a connecting side wall. The connecting side wall forms a buffer part, which can play a role in vibration reduction and deformation absorption, reducing the intensity of vibration transmitted from the second cover portion 102 to the first cover portion 101, reducing the impact of deformation and vibration of the second cover portion 102 on the sealing performance of the connection position of the first cover portion 101, and improving the sealing performance of the connection position between the first cover portion 101 and the frame 202.

[0055] Furthermore, the second cover portion 102 protrudes from the first cover portion 101 by a height of H1mm, where H1mm ranges from 10 to 32mm, specifically any value among 10mm, 15mm, 20mm, 25mm, 30mm, and 32mm, or a value between any two of these. Setting H1mm within this range satisfies the needs for vibration reduction and deformation absorption, ensuring a good seal at the connection between the lower housing 2 and the cover 1. If H1mm is too large, the protrusion of the second cover portion 102 from the first cover portion 101 will be too great, affecting the energy density of the battery pack. If H1mm is too small, the protrusion will be too small, resulting in poor vibration reduction and potential seal failure at the connection between the lower housing 2 and the cover 1. The preferred range for H1mm is 15-22mm.

[0056] In another specific embodiment, the first cover portion 101 and the second cover portion 102 are located on the same plane, that is, the box cover 1 is a flat structure. Although the manufacturing cost of the box cover 1 in this embodiment is lower, the lack of a buffer between the first cover portion 101 and the second cover portion 102 means that vibrations and deformations at the position of the second cover portion 102 are easily transmitted to the first cover portion 101, significantly affecting the sealing performance of the connection between the first cover portion 101 and the frame 202. In this embodiment, d mm ranges from 30 to 150 mm, specifically any value among 30 mm, 50 mm, 70 mm, 90 mm, 120 mm, 135 mm, and 150 mm, or a value between any two values.

[0057] Along the first direction, the distance between the surface of the second cover portion 102 near the battery cell 6 and the top of the battery cell 6 is 5-30mm, specifically any value among 5mm, 10mm, 15mm, 20mm, 25mm, and 30mm, or a value between any two of these. By setting the distance between the surface of the second cover portion 102 near the battery cell 6 and the top of the battery cell 6 within the above range, collisions between the second cover portion 102 and the busbar or flexible circuit board at the top of the battery cell 6 during vibration can be avoided, improving safety. If the above distance is too large, it will affect the energy density of the battery pack; if the above distance is too small, the second cover portion 102 is prone to collisions with the busbar or flexible circuit board at the top of the battery cell 6 during vibration. The busbar is easily deformed by the collision, and the flexible circuit board is prone to poor contact, or even short circuits or insulation failure.

[0058] To further improve the sealing effect at the connection between the lower housing 2 and the housing cover 1, along the first direction, the end face of the bushing 4 near the housing cover 1 protrudes onto the mounting beam 3, as shown in the reference. Figure 4 As shown, the top of the bushing 4 protrudes from the upper surface of the mounting beam 3, and this top of the bushing 4 is the end face of the bushing 4 near the cover 1. This structural design shortens the connection path between the mounting beam 3 and the electric vehicle, making the connection between the fasteners connected to the bushing 4 and the entire vehicle and battery pack more stable, reducing vibration deformation of the mounting beam 3, lowering the risk of breakage of the second surface of the frame 202 and the root of the mounting beam 3, and improving the connection strength between the mounting beam 3 and the frame 202. Figure 7 This is a partial cross-sectional view of the connection position of the bushing 4. In this embodiment, only the end of the bushing 4 near the cover 1 protrudes from one surface of the mounting beam 3, while the end of the bushing 4 away from the cover 1 does not protrude from the other surface of the mounting beam 3. The end of the bushing 4 near the cover 1 is the end where the bushing 4 connects to the body of the electric vehicle.

[0059] Specifically, the height of bushing 4 protruding from the mounting beam 3 is H2mm, as shown in the reference. Figure 4 The range of H2mm is 1-6mm, specifically any value from 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, or any two values. Setting H2mm within this range ensures the sealing effect at the connection between the frame 202 and the cover 1, while also guaranteeing the connection strength between the mounting beam 3 and the frame 202, resulting in better battery pack mounting stability and improved reliability of the mounting beam 3. If the value of H2mm is too large, it shortens the path of the parameter dmm + Lmm, making it easier for vehicle vibrations to be transmitted to the connection between the frame 202 and the cover 1, potentially leading to sealing failure at this connection.

[0060] Along the second direction, the frame 202 includes a frame body and a first end 201 near the lid 1. The first end 201 protrudes from the frame body along the second direction, thereby increasing the sealing area at the connection between the frame 202 and the lid 1, improving the sealing effect, and increasing the connection strength at the connection point. The upper surface of the first end 201 connects to the lid 1, and the second direction is the width direction of the mounting beam 3. The first end 201 is the end of the frame 202 near the lid 1. To improve the sealing performance at the connection between the upper surface of the first end 201 and the lid 1, a sealing gasket is provided between the upper surface of the first end 201 and the connection point of the lid 1. By applying pressure, the sealing gasket undergoes elastic deformation to fill the gap between the two mating surfaces, achieving dustproof, waterproof, and insulating functions. The sealing gasket material includes foamed silicone, EPDM rubber, fluororubber, etc.

[0061] In the second direction, the first end 201 may protrude from both sides of the frame body, or it may protrude from only one side of the frame body. For example... Figure 13 The diagram shows a structure where both sides of the first end 201 protrude from the frame body. Figure 14 and Figure 15 The diagram shows a structure where only one side of the first end 201 protrudes from the frame body. Figure 14 This is a schematic diagram showing the structure where the first end 201 protrudes from the second surface of the frame body away from the battery cell 6. Figure 15 This is a schematic diagram of the structure in which the first end 201 protrudes from the first surface of the frame body near the battery cell 6.

[0062] To ensure a good seal and avoid excessive space occupation by the protruding portion of the first end 201, the height of the first end 201 protruding from the frame body along the second direction is H3 mm. Figure 4 As shown, H3mm ranges from 1.5 to 8mm, specifically any value from 1.5mm, 2.5mm, 4mm, 5.5mm, 7mm, 8mm, or any value between any two. In the embodiment where both sides of the first end 201 protrude from the frame body, the value of H3 is the sum of the heights of the protruding portions on both sides of the first end 201 along the second direction. In the embodiment where only one side of the first end 201 protrudes from the frame body, the value of H3 is the height of the protruding portion on one side of the first end 201 along the second direction. Setting the value of H3mm within the above range can both increase the sealing area at the connection between the frame 202 and the cover 1, improving the sealing effect, and avoid the first end 201 occupying too much space. If the value of H3mm is too small, the sealing area at the connection between the frame 202 and the cover 1 will be too small, resulting in a poor sealing effect at the connection point; if the value is too large, the first end 201 will occupy a large space and increase the weight of the lower casing 2, which is not conducive to the lightweighting of the battery pack.

[0063] In a preferred embodiment, along the second direction, both sides of the first end 201 protrude from the frame body, thereby ensuring the sealing effect at the connection position between the frame 202 and the box cover 1, while also ensuring the connection strength at the connection position.

[0064] To ensure the reliability of the connection between the mounting beam 3 and the vehicle body, at least two first connecting holes 302 are provided on each mounting beam 3 along its length. The mounting beam 3 is connected to the vehicle body through connectors connected within the first connecting holes 302. The length direction of the mounting beam 3 is the third direction. To ensure connection strength while also considering connection efficiency, the spacing between adjacent first connecting holes 302 is Lmm. Figure 6 The range of Lmm is 160-400mm, specifically any value from 160mm, 200mm, 260mm, 300mm, 350mm, 400mm, or any value between any two. If the value of Lmm is too large, the spacing between two adjacent first connecting holes 302 will be too large, which cannot guarantee the reliability of the connection; if the value of Lmm is too small, more first connecting holes 302 need to be set, resulting in too many connecting parts, affecting the connection efficiency between the mounting beam 3 and the vehicle body, and also affecting the structural strength of the mounting beam 3. The preferred range of Lmm is 200-280mm.

[0065] To prevent the transmission of vibration force between two adjacent first connection holes 302 along a third direction, a notch 301 is provided on the mounting beam 3, as shown in the figure. Figure 6 A notch 301 is positioned between two adjacent first connecting holes 302 along a third direction. The first connecting hole 302 is a mounting point connected to the vehicle body. Along the first direction, the notch 301 extends through the mounting beam 3, thereby preventing vibration or stress between the two adjacent mounting points. Along the second direction, the opening of the notch 301 is located away from the frame 202. In other embodiments, spaced openings may also be provided on the mounting beam 3.

[0066] To enhance the vibration energy absorption effect of the mounting beam 3, multiple cavities are arranged along a second direction inside the mounting beam 3. Each cavity extends along a third direction, i.e., along the length of the mounting beam 3, thereby improving the energy absorption and buffering effect of the mounting beam 3. Along the second direction, spacer walls are provided between adjacent cavities to improve the structural strength of the mounting beam. The orthographic projection of the first connecting hole 302 along the first direction does not cover the spacer walls, thus preventing the location of the first connecting hole 302 from affecting the spacer walls and further improving the structural strength of the mounting beam 3.

[0067] In order to make the mounting beam 3 have a better buffering effect, the first connecting holes 302 on the same mounting beam 3 are arranged along the third direction, so that the orthographic projection of the first connecting holes 302 on the mounting beam 3 along the first direction is located at the same cavity position extending along the third direction.

[0068] To facilitate positioning of the mounting beam 3 when it is attached to the vehicle body, a positioning pin 5 is provided on the mounting beam 3, and the positioning pin 5 is connected to the mounting beam 3. To reduce assembly difficulty, one positioning pin 5 is provided on each mounting beam 3. The positioning pin 5 is connected to the mounting beam 3. Understandably, the tip of the positioning pin 5 is positioned towards the box cover 1.

[0069] In order to reduce the transmission of vibration by the positioning pin 5, and at the same time reduce the depth of the pin hole on the vehicle body for inserting the positioning pin 5, and reduce the machining difficulty of the pin hole, the top of the positioning pin 5 is set lower than the upper surface of the box cover 1.

[0070] Furthermore, the height of the top of the positioning pin 5 below the upper surface of the cover 1 is H4 mm. The range of H4 mm is 10-20 mm, specifically any value among 10 mm, 12 mm, 15 mm, 17 mm, 19 mm, and 20 mm, or a value between any two values. Setting the value of H4 mm within the above range can reduce the transmission of vibration while ensuring the positioning effect during installation.

[0071] To ensure reliable sealing at the connection point between the lower housing 2 and the cover 1, the frame 202 is provided with multiple second connection holes for connection with the cover 1. Correspondingly, the cover 1 is provided with a third connection hole 103 for connection with the frame 202. The third connection hole 103 corresponds one-to-one with the second connection holes. The lower housing 2 and the cover 1 are connected by a connector that connects to the third connection hole 103 and the second connection hole, and the connector can be a connecting bolt. To improve the sealing performance of the contact surface between the lower housing 2 and the cover 1, a sealing gasket is provided between their contact surfaces. The material of the sealing gasket can be EPDM rubber, fluororubber, silicone rubber, foamed silicone, or acrylic foam tape, etc. In one embodiment, along the first direction, the orthographic projection of the sealing gasket covers the third connection hole 103. In this embodiment, a fourth connection hole is provided on the sealing gasket, and the fourth connection hole corresponds to the third connection hole 103. In another embodiment, along the first direction, the orthographic projection of the sealing gasket is offset from the third connecting hole 103. In this embodiment, no hole is required on the sealing gasket. Along the second direction, the sealing gasket is at least located on the side of the third connecting hole 103 near the battery cell 6 to ensure a sealing effect. To extend the path length for vibrations of the vehicle body to be transmitted to the connection position between the frame 202 and the cover 1, along the second direction, the projection of the bushing 4 on the frame 202 is located between two adjacent second connecting holes.

[0072] The sealing gasket is preferably elastic foam, which is disposed between the surfaces of the lid 1 and the frame 202 that are close to each other. The elastic modulus of the elastic foam is 10-40 kPa, specifically any value or a value between any two of the following: 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, and 40 kPa. The thickness of the elastic foam is 1-5 mm, specifically any value or a value between any two of the following: 1 mm, 2 mm, 3 mm, 4 mm, 4.5 mm, and 5 mm. The elastic foam has a good cushioning effect and can better absorb impact energy. The elastic foam can be made of silicone foam, silicone rubber, or PU foam.

[0073] The connecting components in the above embodiments can be bolts, studs, or other connection structures commonly used in the art, and are not limited here.

[0074] The value of 'a mm' ranges from 80 to 320 mm, specifically any value from 80 mm, 120 mm, 180 mm, 220 mm, 270 mm, and 320 mm, or any value between two of these ranges. Setting 'a mm' within this range satisfies the sealing requirements of the connection between the frame 202 and the cover 1, ensures the reliability of the connection between the mounting beam 3 and the frame 202, improves the reliability of the mounting beam 3 connection, and prevents cracking at the connection between the mounting beam 3 and the frame 202. If the value of 'a mm' is too small, the path length for vehicle vibration transmitted through the mounting beam 3 to the connection between the frame 202 and the cover 1 is too short, making it easy for vibration to loosen the connecting parts between the lower body 2 and the cover 1, thus affecting the sealing performance of the connection between the lower body 2 and the cover 1. If the value of 'a mm' is too large, the cantilever length of the mounting beam 3 is too large, resulting in poor reliability of the connection between the mounting beam 3 and the frame 202, making the mounting beam 3 prone to cracking at the connection with the frame 202, and leading to poor structural reliability. If the value of a mm is too small, the connector at the connection between the lower housing 2 and the cover 1 is prone to loosening, affecting the sealing effect at the connection between the lower housing 2 and the cover 1. The preferred range of a mm is 140-240 mm. The range of d mm is 30-160 mm, specifically any value of 30 mm, 50 mm, 75 mm, 100 mm, 130 mm, 160 mm, or any value between any two values. Setting d mm within the above range satisfies the sealing requirements at the connection between the frame 202 and the cover 1, and ensures the mounting reliability of the mounting beam 3. If the value of d mm is too small, the path length of the vehicle body vibration transmitted through the mounting beam 3 to the connection between the frame 202 and the cover 1 is short, and vibration is prone to causing the connector between the frame 202 and the cover 1 to loosen, thus affecting the sealing performance at the connection between the frame 202 and the cover 1. If the value of d mm is too large, the mounting stability of the mounting beam 3 is poor, and the mounting reliability of the battery pack is poor. The preferred range for d mm is 50-130 mm.

[0075] The frame 202 includes a first frame plate 2021, a second frame plate 2022, a third frame plate 2023, and a fourth frame plate 2024, as follows: Figure 5The first frame plate 2021, the second frame plate 2022, the third frame plate 2023, and the fourth frame plate 2024 are connected end to end to form a battery placement cavity 204. The first frame plate 2021 and the third frame plate 2023 are arranged opposite each other, and the second frame plate 2022 and the fourth frame plate 2024 are arranged opposite each other. The length of the first frame plate 2021 is greater than the length of the second frame plate 2022. The mounting beam 3 is arranged on the first frame plate 2021 and the third frame plate 2023. The range of 'a' is 80-300mm. The mounting beam 3 is connected to the longer first frame plate 2021 and the third frame plate 2023. Because of its greater length, it is more prone to deformation. Therefore, the upper limit of parameter 'a' is reduced to improve the mounting strength. It is understood that the elastic foam is arranged on the surface of the first frame plate 2021, the second frame plate 2022, the third frame plate 2023, and the fourth frame plate 2024 near the box cover 1 to form a sealed structure surrounding the battery cell 6. The lid 1 and the frame 202 are sealed together by connecting bolts.

[0076] The connection position of adjacent frame plates is at the corner of frame 202. The spacing between adjacent connecting bolts near the corner of frame 202 is smaller than the spacing between adjacent connecting bolts at other positions on frame 202, thereby reducing the deformation of the corner sealing gasket and improving the structural reliability of the corner.

[0077] The battery pack of the present invention ensures the structural strength of the connection between the mounting beam 3 and the frame 202, improves the reliability of battery pack mounting, reduces the risk of breakage at the connection between the mounting beam 3 and the frame 202, improves the structural reliability of the mounting beam 3, reduces the probability of loosening of the sealing bolts at the connection between the cover 1 and the frame 202, and ensures the sealing effect at the connection between the cover 1 and the lower box 2.

[0078] The present invention also provides an electric vehicle, including a chassis and a battery pack, wherein the battery pack is the aforementioned battery pack, and the battery pack is fixedly connected to the chassis via a mounting beam 3.

[0079] In the above embodiments, the method for testing the parameter amm is as follows: along the second direction, the maximum width of the mounting beam 3 is measured using a length measuring tool, measured three times, and the average value is recorded as a mm. The method for testing the parameter dmm is as follows: along the first direction, the distance between the upper end face of the bushing 4 and the upper surface of the cover 1 is measured using a length measuring tool, measured three times, and the average value is recorded as d mm. The accuracy of the length measuring tool is 0.1 mm.

[0080] The preparation of battery cell 6 includes the preparation of positive electrode sheet, negative electrode sheet, electrolyte, and separator. Specifically, the preparation of the positive electrode sheet involves mixing the prepared positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF), adding solvent NMP, and stirring under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated onto both surfaces of the positive electrode current collector foil, air-dried at room temperature, transferred to an oven for further drying, and then rolled and slit to obtain the positive electrode sheet. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1). The preparation of the negative electrode sheet is as follows: The negative electrode active material, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated onto both surfaces of the negative electrode current collector foil, dried at room temperature, and then transferred to an oven for further drying. The negative electrode sheet is then obtained through rolling and slitting. Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96):(4~2):(2~1):(4~1). The preparation of the electrolyte is as follows: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L. The separator is prepared by selecting polyethylene film as the separator. In preparing the battery cell, the positive electrode, separator, and negative electrode are stacked sequentially and wound to form the cell. The tabs of the cell are welded to the terminal assembly, placed in the battery casing, and the cover plate is welded to the casing. The battery is dried, injected with electrolyte, and then encapsulated, allowed to stand, formed, and volume-adjusted to obtain the lithium-ion battery cell.

[0081] In addition to the above-mentioned battery cell material selection, this application may also select other materials, not limited to the materials limited by the above preparation method. The positive electrode active material may be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate. The conductive agent in the positive electrode sheet may also be selected from one or more of graphite, superconducting carbon, Ketjen black, Super P, carbon nanotubes, graphene, and carbon nanofibers. The binder in the positive electrode sheet may also be selected from polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene- The positive electrode current collector can be selected from one or more of the following: tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.; the positive electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, aluminum, nickel, carbon electrode, carbon, nickel, titanium, etc.; the positive electrode current collector can also include composite current collectors, which can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of poly(ethylene terephthalate), polyethylene terephthalate, polyethylene, etc.).

[0082] The negative electrode active material can be selected from one or more of the following negative electrode active main materials: artificial graphite, natural graphite, silicon carbide, silicon oxide, lithium titanate, etc.; the conductive agent in the negative electrode sheet can be selected from one or more of the following: conductive carbon black, conductive graphite, carbon nanotubes, graphene, carbon fiber, etc.; the binder in the negative electrode sheet can be selected from one or more of the following: styrene-butadiene rubber, polyacrylic acid and its salts, sodium alginate, etc.; the thickener in the negative electrode sheet can be selected from one or more of the following: sodium carboxymethyl cellulose, polyacrylonitrile multi-component copolymer, etc.; the negative electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, stainless steel, copper, nickel, carbon electrode, carbon, nickel, titanium, etc.; the negative electrode current collector can also include composite current collectors, which can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.). The negative electrode active layer includes the negative electrode active material, conductive components, adhesives, etc.

[0083] Table 1

[0084]

[0085] Performance Test 1: Battery Pack Sealing Test

[0086] According to the above battery preparation method, 200 corresponding battery cells are prepared and stacked in the lower box of the battery pack. The bottom surface of the battery cells is bonded and fixed to the lower box. A sealing element is set between the box cover and the lower box. The box cover of the battery pack is closed and the box cover and the frame are fixedly connected by fasteners. The values ​​of a and d in each embodiment and comparative example are shown in Table 1. Except for the above, the other structures are the same.

[0087] According to GB / T4208-2017, the battery pack is subjected to a waterproof test. The battery pack is continuously immersed in water to a depth of 1 meter for 48 hours. Then the battery pack is opened and the inside of the battery pack is inspected for water intrusion at the seal between the protrusion and the cover. If no water intrusion occurs, the battery pack is qualified; if water intrusion occurs, the battery pack is unqualified.

[0088] Performance Test 2: Mounting Strength Test

[0089] According to the above battery preparation method, 200 corresponding battery cells are prepared and stacked in the lower box of the battery pack. The bottom surface of the battery cells is bonded and fixed to the lower box. A sealing element is set between the box cover and the lower box. The box cover of the battery pack is closed and the box cover and the frame are fixedly connected by fasteners. The values ​​of a and d in each embodiment and comparative example are shown in Table 1. Except for the above, the other structures are the same.

[0090] (1) Before the test begins, along the second direction, use a length measuring tool to measure the distance between the upper end face of the bushing and the upper surface of the box cover. Measure 3 times and take the average value, which is recorded as d 1mm.

[0091] (2) In accordance with the requirements of GB / T2423.43, the mounting beam of the battery pack is fixedly connected to the test bracket with fasteners. Then, the test bracket is installed on the vibration table, and the battery pack is suspended on the test bracket with the battery pack and the vibration table spaced apart. The test process is carried out in accordance with the provisions of GB / T2423.56. Random and fixed-frequency vibration loads are applied in each direction respectively. The loading sequence should be random z-axis, fixed z-axis, random y-axis, fixed y-axis, random x-axis, fixed x-axis (the direction of the line connecting the front and rear of the battery pack is the x-axis direction, and the other horizontal direction perpendicular to the x-axis direction is the y-axis direction). The vibration frequency, power spectral density (PSD), vibration time, etc. are shown in Table 2.

[0092] Table 2

[0093]

[0094] (3) After the vibration ends, along the second direction, use a length measuring tool to measure the distance between the upper end face of the bushing and the upper surface of the box cover. Measure 3 times, take the average value and record it as d2 mm. Calculate the degree of deformation of the mounting part t=(d2-d1) / d1. When t is greater than 2%, the degree of deformation of the mounting part is recorded as unqualified; when t is less than or equal to 2%, the degree of deformation of the mounting part is recorded as qualified.

[0095] The battery packs described above were used in the experiments, and the data obtained are shown in Table 1, Examples 1 to 11. In Examples 1 to 11, the performance parameters of the selected test samples met the following requirements: a×d ranged from 2512 to 49680. In the battery pack sealing test, the sealing performance of the sample battery packs all met the design requirements. In the battery pack load strength test, the load strength of the battery packs in the above examples all met the set requirements.

[0096] In Comparative Examples 1 through 4, the range of a×d is not within the specified numerical range. In Comparative Examples 1 and 3, the value of a×d is less than 2512, and the sealing performance of the battery pack does not meet the design requirements; however, the load-bearing strength of the battery pack meets the setting requirements. In Comparative Examples 2 and 4, the value of a×d is greater than 49680, and the sealing performance of the battery pack meets the design requirements; however, the load-bearing strength of the battery pack does not meet the setting requirements.

[0097] In the description of this solution, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this solution, "multiple" means two or more, unless otherwise explicitly specified.

[0098] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0099] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery pack, characterized in that, The enclosure includes a housing and multiple battery cells disposed within the housing. The housing includes a lower housing and a cover. The lower housing includes a frame and a base plate. The frame encloses a battery placement cavity. Along a first direction, the frame has a first opening and a second opening disposed opposite to each other. The first direction is the height direction of the frame. The cover seals the first opening, and the base plate seals the second opening. The battery cells are disposed on the surface of the base plate near the cover and are fixedly connected to the base plate. The first opening is sealed to the cover. The frame includes a first surface near the battery cell and a far... At least one mounting beam protrudes from the second surface of the battery cell in a direction away from the battery cell. The mounting beam is fixedly connected to the second surface. Along a first direction, the mounting beam has an upper surface and a lower surface arranged opposite to each other. The upper surface is closer to the cover than the lower surface. The mounting beam has a first connecting hole that penetrates the upper and lower surfaces. A bushing is provided inside the first connecting hole. The bushing is used to connect fasteners for connecting the electric vehicle. The width of the mounting beam along a second direction is a mm, where the second direction is the width direction of the mounting beam. Along the first direction, the distance between the end face of the bushing near the cover and the surface of the cover away from the battery cell is d mm. The range of a×d is 2512-49680.

2. The battery pack according to claim 1, characterized in that, The cover includes a first cover portion and a second cover portion. The first cover portion and the frame at least partially overlap in orthographic projection along a first direction. The second cover portion is correspondingly disposed with the battery placement cavity. The first cover portion surrounds the second cover portion.

3. The battery pack according to claim 2, characterized in that, The first cover portion and the second cover portion are located on the same plane, and the range of d mm is 30-150 mm.

4. The battery pack according to claim 2, characterized in that, The second cover portion protrudes from the first cover portion in a direction away from the battery cell.

5. The battery pack according to claim 4, characterized in that, The second cover portion protrudes from the first cover portion by a height of H1mm, and H1mm ranges from 10 to 32mm.

6. The battery pack according to claim 2, characterized in that, Along the first direction, the distance between the surface of the second cover portion near the battery cell and the top of the battery cell is 5-30mm.

7. The battery pack according to claim 1, characterized in that, Along the first direction, the end face of the bushing near the box cover protrudes onto the mounting beam.

8. The battery pack according to claim 7, characterized in that, The bushing protrudes from the mounting beam by a height of H2mm, where H2mm ranges from 1 to 6mm.

9. The battery pack according to claim 1, characterized in that, Along the second direction, the frame includes a frame body and a first end near the box cover. The first end protrudes from the frame body along the second direction, and the upper surface of the first end is connected to the box cover. The second direction is the width direction of the mounting beam.

10. The battery pack according to claim 9, characterized in that, Along the second direction, the height of the first end protruding from the frame body is H3 mm, and the range of H3 mm is 1.5-8 mm.

11. The battery pack according to claim 9, characterized in that, Along the second direction, both sides of the first end protrude from the frame body.

12. The battery pack according to claim 1, characterized in that, Along a third direction, each of the aforementioned mounting beams is provided with at least two of the first connection holes; The spacing between adjacent first connecting holes is Lmm, and Lmm ranges from 160 to 400mm, with the third direction being the length direction of the mounting beam.

13. The battery pack according to claim 12, characterized in that, The mounting beam has a notch, which is located between two adjacent first connecting holes along a third direction.

14. The battery pack according to claim 12, characterized in that, The mounting beam has multiple cavities arranged along the second direction, each cavity extending along the third direction, and a partition wall between adjacent cavities. The orthographic projection of the first connecting hole along the first direction does not cover the partition wall.

15. The battery pack according to claim 14, characterized in that, The first connecting holes on the same mounting beam are arranged along a third direction.

16. The battery pack according to claim 1, characterized in that, The mounting beam is equipped with a positioning pin, which is connected to the mounting beam.

17. The battery pack according to claim 16, characterized in that, The top of the positioning pin is set below the upper surface of the box cover.

18. The battery pack according to claim 17, characterized in that, The height of the top of the positioning pin below the upper surface of the box cover is H4 mm, and the range of H4 mm is 10-20 mm.

19. The battery pack according to claim 1, characterized in that, The frame is provided with a plurality of second connection holes for connecting with the box cover. Along the second direction, the orthographic projection of the bushing on the frame is located between two adjacent second connection holes.

20. The battery pack according to claim 1, characterized in that, The range of a mm is 80-320 mm; And / or, d mm ranges from 30 to 160 mm.

21. The battery pack according to claim 1, characterized in that, The frame includes a first frame plate, a second frame plate, a third frame plate, and a fourth frame plate. The first frame plate, the second frame plate, the third frame plate, and the fourth frame plate are connected end to end to form the battery placement cavity. The first frame plate and the third frame plate are arranged opposite each other, and the second frame plate and the fourth frame plate are arranged opposite each other. The length of the first frame plate is greater than the length of the second frame plate. The mounting beam is arranged on the first frame plate and the third frame plate. The range of a is 80-300mm.

22. The battery pack according to claim 21, characterized in that, The lid and the frame are sealed together by connecting bolts. Elastic foam is provided between the close surfaces of the lid and the frame. The elastic modulus of the elastic foam is 10-40 kPa and the thickness of the elastic foam is 1-5 mm.

23. The battery pack according to claim 22, characterized in that, The connection position of adjacent frame plates is at the corner of the frame. The spacing between adjacent connecting bolts near the corner of the frame is smaller than the spacing between adjacent connecting bolts at other positions on the frame.

24. An electric vehicle, comprising a chassis and a battery pack, characterized in that, The battery pack is the battery pack according to any one of claims 1-23, and the battery pack is fixedly connected to the chassis by a mounting beam.

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