battery pack

Abstract

This invention discloses a battery pack having three perpendicular directions: a first direction, a second direction, and a third direction. The battery pack body includes a shell, a lifting cylinder, and a battery assembly. The shell has a cavity. The lifting cylinder penetrates the upper and lower sidewalls of the shell along the first direction, and its two axial ends are connected to the upper and lower sidewalls of the shell. An axial through-hole is formed inside the lifting cylinder. The battery assembly is disposed within the cavity and includes multiple individual batteries. The battery closest to the lifting cylinder is designated as the first battery. The distance between the first battery and the lifting cylinder is y mm, and the inner diameter of the through-hole is z mm, where 0.6 ≤ y / z ≤ 1.5. This invention ensures the performance and lifespan of the battery pack.

Description

Technical Field

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

[0002] The battery pack is the main carrier of an electric vehicle. The battery pack is usually fixed to the vehicle floor by a suspension method. Specifically, the battery pack is equipped with a lifting cylinder, and then lifting bolts are inserted into the lifting cylinder so that the lifting bolts are hung on the vehicle to complete the installation of the battery pack.

[0003] Since the cavity inside the hoisting cylinder is considered the external space of the battery pack, and the hoisting cylinder runs through the battery pack, the batteries inside the battery pack can dissipate heat through the hoisting cylinder. The batteries inside the battery pack that are closer to the hoisting cylinder have a greater heat exchange than the batteries in other locations, which can lead to uneven temperature distribution throughout the battery pack. This, in turn, can cause a decrease in the consistency of the battery pack's electrical performance, affecting the performance and lifespan of the battery pack. Summary of the Invention

[0004] The purpose of this invention is to provide a battery pack that ensures the performance and lifespan of the battery pack.

[0005] To address the aforementioned technical problems, the present invention provides the following technical solution:

[0006] A battery pack having two perpendicular directions—a first direction, a second direction, and a third direction—comprising a battery pack body, the battery pack body comprising:

[0007] The outer casing has an internal cavity.

[0008] A lifting cylinder extends through the upper and lower sidewalls of the outer casing along a first direction, and the two ends of the lifting cylinder along the axial direction are connected to the upper and lower sidewalls of the outer casing respectively. A through hole is formed inside the lifting cylinder along the axial direction.

[0009] A battery pack is disposed within the accommodating cavity. The battery pack includes multiple individual cells, and among the multiple individual cells, the individual cell closest to the hoisting cylinder is the first cell.

[0010] Wherein, the distance between the first battery and the hoisting cylinder is y mm, the inner diameter of the through hole is z mm, and 0.6≤y / z≤1.5.

[0011] Compared with the prior art, the battery pack of this invention has the following advantages:

[0012] In this invention, the battery pack body is typically equipped with a lifting cylinder, and then the battery pack body is mounted on the vehicle body via bolts, screws, and other mounting components passing through the lifting cylinder. On one hand, since the through-holes inside the lifting cylinder are considered external space compared to the internal accommodating cavity of the battery pack body, the individual cells within the accommodating cavity can also exchange heat with the outside through these through-holes. The through-holes have a certain impact on the heat dissipation of the individual cells within the accommodating cavity. Specifically, among the multiple individual cells within the casing, the heat dissipation effect of the individual cells closer to the through-holes is better than that of the individual cells farther away from the through-holes. This can easily lead to uneven temperature distribution within the battery pack, resulting in poor consistency in the battery pack's electrical performance, ultimately affecting the battery pack's performance and lifespan. The larger the diameter of the through-holes, the better the heat dissipation effect of the individual cells closer to the through-holes, thus further worsening the consistency in the battery pack's electrical performance.

[0013] On the other hand, the diameter of the through hole of the lifting cylinder also determines the size of the mount connected to the vehicle body. The size of the mount determines its own load-bearing capacity and the lifting strength of the battery pack. The larger the diameter of the through hole, the greater the lifting strength of the mount on the battery pack.

[0014] When y / z is greater than 1.5, it indicates that the distance between the first battery and the lifting cylinder is too large, while the diameter of the through-hole of the lifting cylinder is too small. Although this ensures uniform temperature among the battery packs and guarantees battery pack performance, the lifting strength of the battery pack is poor. When y / z is less than 0.6, it indicates that the distance between the first battery and the lifting cylinder is too small, while the diameter of the through-hole of the lifting cylinder is too large. Although this ensures lifting strength, the heat dissipation of the first battery is large, resulting in uneven temperature among the battery packs, poor battery pack performance, and a reduced lifespan. Therefore, 0.6 ≤ y / z ≤ 1.5 is recommended to ensure battery pack performance and stable connection to the vehicle body. Attached Figure Description

[0015] Figure 1 This is a top view of the overall structure of an embodiment of the present invention;

[0016] Figure 2 yes Figure 1 Sectional view of BB;

[0017] Figure 3 yes Figure 1 Enlarged view of point A in the middle;

[0018] Figure 4 This is a schematic diagram showing the dimensions between the hoisting cylinder, the first battery, and the support beam in an embodiment of the present invention;

[0019] Figure 5 This is a schematic diagram showing the dimensions of the hoisting cylinder, partition, and support beam in an embodiment of the present invention;

[0020] Figure 6 This is a schematic diagram showing the dimensions of the first and second lifting cylinders in an embodiment of the present invention;

[0021] Figure 7 This is a schematic diagram of the explosion-proof valve and the weak point in an embodiment of the present invention.

[0022] In the diagram, 1 is the outer shell; 11 is the accommodating cavity; 12 is the housing; 121 is the base plate; 122 is the frame; 123 is the weak point; and 13 is the cover.

[0023] 2. Lifting cylinder; 21. Through hole; 22. Limiting part; 23. First lifting cylinder; 24. Second lifting cylinder; 25. Third lifting cylinder;

[0024] 3. Battery pack; 31. First battery; 311. Housing; 312. Battery cell; 313. Explosion-proof valve;

[0025] 4. Support beam; 41. Reinforcing rib; 42. First cavity;

[0026] 5. Partition; 51. Rib; 52. Second cavity;

[0027] 6. Heat exchange plate. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] In the description of this invention, it should be understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, parts, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, parts, components, and / or groups thereof. It should be understood that when we say a part is "connected" to another part, it can be directly connected to the other part, or there may be intermediate parts. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0030] like Figures 1 to 7As shown, the present invention relates to a battery pack having two perpendicular directions: a first direction, a second direction, and a third direction. The battery pack includes a battery pack body, where the first direction is the height direction of the battery pack body, the second direction is the width direction of the battery pack body, and the third direction is the length direction of the battery pack body. The battery pack body includes a shell 1, a lifting cylinder 2, and a battery pack 3. The shell 1 has an internal cavity 11. The lifting cylinder 2 penetrates the upper and lower sidewalls of the shell 1 along the first direction, and its two ends along the axial direction are connected to the upper and lower sidewalls of the shell 1. The lifting cylinder 2 has an axial through-hole 21 inside, and its two ends penetrate the upper and lower sidewalls of the shell 1. The battery pack 3 is disposed within the cavity 11 and includes multiple individual batteries. Among the multiple individual batteries, the individual battery closest to the lifting cylinder 2 is the first battery 31.

[0031] Wherein, the distance between the first battery 31 and the hoisting cylinder 2 is y mm, the inner diameter of the through hole 21 is z mm, and 0.6 ≤ y / z ≤ 1.5. Specifically, the value of y / z can be 0.8, 0.9, 1.1, 1.3 or 1.4.

[0032] It should be noted that the first battery 31 can be one or more. When there is only one single battery facing the hoisting cylinder 2, that single battery is the first battery 31. When multiple single batteries are arranged side by side and facing the hoisting cylinder 2, and the distance between the multiple single batteries and the hoisting cylinder 2 is the same, all of the multiple single batteries are the first battery 31. When multiple single batteries are stacked and the distance between the multiple single batteries and the hoisting cylinder 2 is the same, all of the multiple single batteries are the first battery 31.

[0033] In this invention, the battery pack body is typically equipped with a lifting cylinder 2. The battery pack body is then mounted on the vehicle body via bolts, screws, or other mounting components passing through the lifting cylinder 2. On one hand, since the through-hole 21 inside the lifting cylinder 2 is considered external space compared to the internal accommodating cavity 11 of the battery pack body, the individual batteries within the accommodating cavity 11 can also exchange heat with the outside through the through-hole 21. The through-hole 21 has a certain impact on the heat dissipation of the individual batteries within the accommodating cavity 11. Specifically, among the multiple individual batteries within the outer casing 1, the heat dissipation effect of the individual batteries closer to the through-hole 21 is better than that of the individual batteries farther away from the through-hole 21. This easily leads to uneven temperature distribution in the battery pack 3, resulting in poor electrical performance consistency and ultimately affecting the performance and lifespan of the battery pack. The larger the diameter of the through-hole 21, the better the heat dissipation effect of the individual batteries closer to the through-hole 21, thus further worsening the electrical performance consistency of the battery pack 3.

[0034] On the other hand, the diameter of the through hole 21 of the lifting cylinder 2 also determines the size of the mount connected to the vehicle body. The size of the mount determines its own load-bearing capacity and the lifting strength of the battery pack. The larger the diameter of the through hole 21, the greater the lifting strength of the mount on the battery pack.

[0035] When y / z is greater than 1.5, it indicates that the distance between the first battery 31 and the lifting cylinder 2 is too large, while the diameter of the through hole 21 of the lifting cylinder 2 is too small. Although this ensures uniform temperature among the battery packs 3 and guarantees battery pack performance, the lifting strength of the battery pack is poor. When y / z is less than 0.6, it indicates that the distance between the first battery 31 and the lifting cylinder 2 is too small, while the diameter of the through hole 21 of the lifting cylinder 2 is too large. Although this ensures lifting strength, the heat dissipation of the first battery 31 is large, resulting in uneven temperature distribution in the battery pack 3, poor battery pack performance, and a reduced lifespan. Therefore, 0.6 ≤ y / z ≤ 1.5 is recommended to ensure the performance of the battery pack and the stability of its connection to the vehicle body.

[0036] In some embodiments, the distance between the first battery 31 and the hoisting cylinder 2 is y mm, where 11.5 mm ≤ y ≤ 23.5 mm. Specifically, the value of y can be 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 21 mm, or 23 mm.

[0037] When the distance y between the first battery 31 and the lifting cylinder 2 is too large, although it ensures the uniformity of the battery pack 3 temperature, it will occupy too much space inside the accommodating cavity 11, affecting the energy density of the battery pack. When the distance y between the first battery 31 and the lifting cylinder 2 is too small, it will lead to uneven temperature of the battery pack 3, affecting the performance of the battery pack. Therefore, 11.5mm≤y≤23.5mm is set to balance the energy density and performance of the battery pack.

[0038] In some embodiments, the inner diameter of the through hole 21 is z mm, where 16 mm ≤ z ≤ 19 mm. Specifically, the value of z can be 16.5 mm, 17 mm, 18 mm, or 18.5 mm.

[0039] When the inner diameter z of the through hole 21 is too large, the size of the lifting cylinder 2 will also be too large, which will also occupy the space of the accommodating cavity 11. When the inner diameter z of the through hole 21 is too small, the size of the mounting component will also be reduced, thereby affecting the mounting strength of the battery pack.

[0040] In some embodiments, a support beam 4 is also included, which is disposed within the accommodating cavity 11 and extends along a second direction. The battery pack 3 is provided on both sides of the support beam 4 in a third direction, and the hoisting cylinder 2 at least partially penetrates the support beam 4 along a first direction.

[0041] Specifically, the support beam 4 is located inside the accommodating cavity 11 and extends along the width direction of the battery pack. The two ends of the support beam 4 are connected to the opposite side walls of the accommodating cavity 11. The battery pack 3 is located inside the accommodating cavity 11 and on both sides of the support beam 4. The lifting cylinder 2 penetrates the outer shell 1 along the height direction and at least partially passes through the support beam 4. That is, the lifting cylinder 2 is combined with the support beam 4, so that the mounting component can securely mount the battery pack to the vehicle body through the lifting cylinder 2.

[0042] In some embodiments, the support beam 4 is provided with a plurality of reinforcing ribs 41, and the plurality of reinforcing ribs 41 form a plurality of first cavities 42 in the support beam 4. The hoisting cylinder 2 is located in one of the first cavities 42, and there is a gap between the outer side of the hoisting cylinder 2 and the inner side of the first cavity 42.

[0043] That is, the hoisting cylinder 2 penetrates the support beam 4, and the first cavity 42 completely surrounds the support beam 4. Thus, the first cavity 42 can play a role in heat insulation, reducing the heat exchange between the first battery 31 and the through hole 21 of the hoisting cylinder 2, which helps to ensure the uniform temperature of the battery pack.

[0044] In some embodiments, the distance between the side of the support beam 4 facing the first battery 31 and the first battery 31 is M mm, where 0.26 ≤ (yM) / z ≤ 0.6, and 6.5 mm ≤ M ≤ 14 mm. Specifically, the value of (yM) / z can be 0.28, 0.3, 0.32, 0.35, 0.37, 0.39, 0.4, 0.42, 0.44, 0.46, 0.48, 0.5, 0.52, 0.55, 0.58, or 0.59; and the value of M can be 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, or 13.5 mm.

[0045] When (yM) / z is too large, it indicates that the size of the first cavity 42 inside the support beam 4 is too large, which will lead to insufficient structural strength of the support beam 4. Under continuous pressure from the hoisting load, the support beam 4 is prone to crushing and deformation. When (yM) / z is too small, it indicates that the size of the hoisting cylinder 2 is large but the size of the first cavity 42 is small, which can easily increase the heat transfer efficiency between the first battery 31 and the hoisting cylinder 2, which is not conducive to the uniform temperature of the battery pack 3. Therefore, it is necessary to keep 0.26≤(yM) / z≤0.6 to ensure the structural strength of the support beam 4 and ensure the uniform temperature of the battery pack 3, thus ensuring the stability and performance of the battery pack.

[0046] In some embodiments, the distance between the lifting cylinder 2 and the inner wall of the first cavity 42 facing away from the first battery 31 is d mm, where 5 mm ≤ d ≤ 9.5 mm. Specifically, the value of d can be 5.5 mm, 6 mm, 7 mm, 8 mm, or 9 mm.

[0047] That is, by keeping 5mm≤d≤9.5mm, the heat transfer between the first battery 31 and the hoisting cylinder 2 can be reduced, and the hoisting cylinder 2 and the first cavity 42 can be kept away from the inner wall of the first battery 31, which would result in insufficient arrangement space.

[0048] In some embodiments, the distance between the hoisting cylinder 2 and the support beam 4 on one side in the third direction is the same as the distance between the hoisting cylinder 2 and the support beam 4 on the other side in the third direction.

[0049] That is, the distance between the hoisting cylinder 2 and one of the wide side walls of the support beam 4 is the same as the distance between the hoisting cylinder 2 and the other wide side wall of the support beam 4, so that the hoisting cylinder 2 is in the center position of the support beam 4 along the width direction, thereby making the structure symmetrical and improving the stability of the battery pack mounting.

[0050] In some embodiments, the thickness of the sidewall of the hoisting cylinder 2 is T1 mm, where 2 ≤ z / T1 ≤ 5.5. Specifically, the value of z / T1 can be 2.5, 3, 3.5, 4, 4.5 or 5.

[0051] When z / T1 is too large, it indicates that the sidewall of the lifting cylinder 2 is thin, while the diameter of the through hole 21 of the lifting cylinder 2 is large. On the one hand, this facilitates heat transfer between the first battery 31 and the lifting cylinder 2; on the other hand, the mechanical strength of the lifting cylinder 2 itself and its sealing strength with the outer shell 1 are insufficient. When z / T1 is too small, it indicates that the sidewall of the lifting cylinder 2 is thick, while the diameter of the through hole 21 of the lifting cylinder 2 is small. This results in a smaller size of the mounting component that passes through the through hole 21, leading to weaker mounting strength for the battery pack and affecting the stability of the battery pack on the vehicle body. Therefore, maintaining 2≤z / T1≤5.5 can reduce the heat transfer between the lifting cylinder 2 and the first battery 31 while ensuring the mounting strength for the battery pack.

[0052] In some embodiments, the thickness of the sidewall of the hoisting cylinder 2 is T1 mm, where 3.5 mm ≤ T1 ≤ 8 mm. Specifically, the value of T1 can be 4 mm, 4.5 mm, 5 mm, 6 mm, 7 mm, or 7.5 mm.

[0053] If T1 is too large, the weight of the lifting cylinder 2 will also be large, which is not conducive to the lightweighting of the battery pack and the inability to arrange more individual cells, which will affect the improvement of the energy density of the battery pack. If T1 is too small, it will not be conducive to the heat insulation between the first battery 31 and the lifting cylinder 2. Therefore, it is necessary to keep 3.5mm≤T1≤8mm to ensure the energy density of the battery pack and to ensure the uniform temperature of the battery pack 3, thus ensuring the performance of the battery pack.

[0054] In some embodiments, the battery pack body further includes a separator 5, which is disposed between the support beam 4 and the first battery 31. The thermal conductivity of the separator 5 is k1 W / (mK), where k1 ≤ 0.46 W / (mK). Specifically, the value of K1 can be 0.1, 0.15, 0.18, 0.22, 0.25, 0.28, 0.3, 0.33, 0.35, 0.38, 0.4, 0.42, 0.44, or 0.45.

[0055] Since the partition 5 has a heat insulation function and the thermal conductivity k1 of the partition 5 is ≤0.46W / (mK), the heat transfer between the first battery 31 and the hoisting cylinder 2 can be reduced.

[0056] In some embodiments, the distance between the first battery 31 and the hoisting cylinder 2 is y mm, and the inner diameter of the through hole 21 is z mm, wherein 0.7 ≤ y / z ≤ 1.1, and 15 mm ≤ y ≤ 17 mm.

[0057] Because there is a partition 5 for heat insulation between the support beam 4 and the first battery 31, the distance between the first battery 31 and the hoisting cylinder 2 can be reduced, which is beneficial to improving the space utilization rate inside the battery pack and reducing the width dimension of the support beam 4, thereby improving the energy density of the battery pack.

[0058] In some embodiments, in a first direction, the partition 5 extends upward beyond the upper end face of the support beam 4, wherein 0.65≤y / z≤0.95 and 13mm≤y≤15mm.

[0059] That is, in the height direction, the upper end of the partition 5 extends upward and beyond the upper end surface of the support beam 4, so that the partition 5 can completely cover the heat transfer surface of the support beam 4 facing the first battery 31, further reducing the heat transfer between the first battery 31 and the support beam 4, which can make the distance between the first battery 31 and the hoisting cylinder 2 smaller, which is beneficial to improving the energy density of the battery pack.

[0060] In some embodiments, in a first direction, the separator 5 extends upward beyond the upper surface of the first battery 31, where 0.6 ≤ y / z ≤ 0.68 and 11.5 mm ≤ y ≤ 13 mm.

[0061] That is, in the height direction, the upper end of the partition 5 extends upward and beyond the upper surface of the first battery 31, so that the partition 5 completely covers the heat transfer surface of the first battery 31 facing the hoisting cylinder 2, resulting in better heat insulation effect. This can further reduce the distance between the first battery 31 and the hoisting cylinder 2, which is beneficial to improving the energy density of the battery pack.

[0062] In some embodiments, in the third-party direction, the thickness of the partition 5 is T2mm, where 5mm≤T2≤13mm. Specifically, the value of T2 can be 5.5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm or 12.5mm.

[0063] That is, the thickness of the partition 5 is kept between 5mm and 13mm, so as to avoid the partition 5 being too thick and taking up too much space, and also to avoid the partition 5 being too thin and affecting the heat insulation effect.

[0064] In some embodiments, the partition 5 is provided with a plurality of protruding ribs 51 on the side facing the support beam 4, and the protruding ribs 51 abut against the support beam 4, and a plurality of second cavities 52 are formed between the plurality of protruding ribs 51, the partition 5 and the support beam 4.

[0065] A second cavity 52 is formed between the partition 5 and the support beam 4, which helps to reduce the heat transfer from the first battery 31 to the support beam 4 and the hoisting cylinder 2, and ensures that the battery pack 3 has a uniform temperature.

[0066] In some embodiments, a fixing adhesive layer is provided in the second cavity 52, and the partition 5 is fixed to the support beam 4 through the fixing adhesive layer.

[0067] The fixing adhesive layer can be structural adhesive or double-sided adhesive to fix the partition 5 to the support beam 4 together.

[0068] In some embodiments, the battery pack 3 abuts against the separator 5, and the inner diameter of the through hole 21 is z mm, wherein 16 mm ≤ z ≤ 17 mm.

[0069] Since the fixing adhesive layer bonds the separator 5 and the support beam 4 together, and the battery pack 3 is in contact with the separator 5, there are more force transmission paths and the force application area is larger. Therefore, while ensuring structural stability, the inner diameter of the through hole 21 can be reduced, which is beneficial to improving the energy density of the battery pack.

[0070] In some embodiments, at least one of the protruding ribs 51 and the reinforcing ribs 41 in the support beam 4 are staggered, and the wall thickness of the support beam 4 is T3mm, wherein T3 ≥ 2mm. Specifically, the value of T3 can be 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, 5.2mm, 5.5mm, 5.8mm, or 6mm.

[0071] Because the ribs 51 on the partition 5 and the reinforcing ribs 41 in the support beam 4 are misaligned, the first cavity 42 and the second cavity 52 will also be misaligned, which helps to improve the overall structural strength of the battery pack. At the same time, since the ribs 51 and the reinforcing ribs 41 act on the support beam 4 at different positions, it is necessary to increase the wall thickness of the support beam 4 to be greater than 2mm, so as to ensure the strength of the support beam 4.

[0072] In some embodiments, the plurality of reinforcing ribs 41 in the support beam 4 are arranged one-to-one with the plurality of protruding ribs 51 on the partition plate 5.

[0073] Since the ribs 51 on the partition 5 and the reinforcing ribs 41 in the support beam 4 are aligned, that is, the first cavity 42 and the second cavity 52 are also aligned, the force transmission path is shorter. Thus, the mounting force applied to the lifting cylinder 2 by the mounting component is directly distributed through the reinforcing ribs 41, making the support beam 4 less prone to deformation and ensuring the stability of the battery pack mounted on the vehicle body.

[0074] In some embodiments, the interior of the first cavity 42 and / or the second cavity 52 is filled with a heat-insulating medium, which can further reduce heat transfer between the first battery 31 and the hoisting cylinder 2, thereby ensuring uniform temperature of the battery pack 3 and ensuring the performance and lifespan of the battery pack.

[0075] In some embodiments, a buffer is provided between the separator 5 and the first battery 31.

[0076] Specifically, a buffer is provided between the battery pack 3 and the separator 5. The buffer can be foam or a buffer adhesive layer. The buffer has a heat insulation function on the one hand, and on the other hand, when the battery pack is assembled, the battery pack 3 and the separator 5 compress the buffer and then insert it into the outer shell 1 of the battery pack body. Then the buffer expands to make the battery pack 3 securely inside the outer shell 1.

[0077] In some embodiments, in the third-party direction, the thickness of the buffer is T4mm, where 1.5mm≤T4≤4mm. Specifically, the value of T4 can be 1.7mm, 1.9mm, 2mm, 2.2mm, 2.4mm, 2.5mm, 2.7mm, 2.9mm, 3mm, 3.2mm, 3.4mm, 3.5mm, 3.7mm, or 3.9mm.

[0078] The buffer has a certain heat insulation performance. If the thickness of the buffer is too large, it will occupy too much space in the accommodating cavity 11. If the thickness of the buffer is too small, the heat insulation effect will be poor. Therefore, the thickness of the buffer is kept between 1.5mm and 4mm to ensure that the energy density of the battery pack is not affected and that it has a certain heat insulation performance.

[0079] In some embodiments, a connecting adhesive layer is provided between the lifting cylinder 2 and the first battery 31, and the thermal conductivity of the connecting adhesive layer is k2 W / (mK), wherein k2 ≤ 0.8 W / (mK). Specifically, the value of k2 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 or 0.7.

[0080] Specifically, the connecting adhesive layer can be disposed between the separator 5 and the first battery 31, or between the support beam 4 and the separator 5, thereby improving the mode of the battery module and reducing the misalignment of the cell 312 after the battery pack vibrates in the height direction. The thermal conductivity k2 between the hoisting cylinder 2 and the first battery 31 is ≤0.8W / (mK), so that the connecting adhesive layer has a heat insulation effect.

[0081] In some embodiments, the largest side of the first battery 31 faces the support beam 4, wherein 0.6 ≤ y / z ≤ 1.1.

[0082] When the largest side of the first cell 31 in the single cell faces the support beam 4, the heat transfer of the first cell 31 to the hoisting cylinder 2 is greater. In order to ensure the uniform temperature of the battery pack 3, it is necessary to maintain 0.6≤y / z≤1.1.

[0083] In some embodiments, the first battery 31 includes a housing 311 and a battery cell 312. The battery cell 312 is disposed within the housing 311. In a first direction, the height of the battery cell 312 is h1 mm, and the height of the housing 311 is h2 mm, wherein h1 / h2 ≤ 0.98. Specifically, the value of h1 / h2 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.95.

[0084] That is, the ratio of the height of the battery cell 312 to the height of the housing 311 is less than 0.98, so that the height of the battery cell 312 is less than the height of the housing 311, thereby reducing the heat transfer between the largest side of the first battery 31 and the hoisting cylinder 2.

[0085] In some embodiments, the lower end of the hoisting cylinder 2 extends in a third direction to form a limiting portion 22, and the limiting portion 22 extends beyond the side of the support beam 4 facing the first battery 31.

[0086] The lower end of the hoisting cylinder 2 extends in the length direction of the battery pack to form a limiting part 22, and the limiting part 22 extends beyond the support beam 4. That is, the limiting part 22 can support the support beam 4 to apply the load force to the support beam 4, which is beneficial to the distribution of force and makes the battery pack mounting more stable.

[0087] In some embodiments, the limiting portion 22 extends toward a third direction and beyond the side of the partition 5 opposite the first battery 31.

[0088] That is, the limiting part 22 continues to extend in the length direction of the battery pack and goes beyond the side of the separator 5 facing the first battery 31, so that the limiting part 22 can effectively support the separator 5, so that the load force is applied to the support beam 4 and the separator 5, which is more conducive to the distribution of force, thereby making the battery pack load more stable.

[0089] In some embodiments, the projection of the limiting portion 22 in the first direction and the projection of the first battery 31 in the first direction partially overlap.

[0090] That is, the limiting part 22 continues to extend along the length of the battery pack and extends to the battery pack 3, so that the limiting part 22 can also effectively support the battery pack 3, so that the load force is applied to the support beam 4, the partition 5 and the battery pack 3, which is more conducive to the distribution of force, thereby making the battery pack mounting more stable.

[0091] In some embodiments, in the third direction, the width of the limiting part 22 is w mm, and in the first direction, the height of the supporting beam 4 is h3 mm, wherein 0.15 ≤ w / h3 ≤ 0.29, 15 mm ≤ w ≤ 20 mm, and 70 mm ≤ h3 ≤ 95 mm. Specifically, the value of w can be 15.5 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 19.5 mm; the value of h3 can be 72 mm, 74 mm, 78 mm, 80 mm, 82 mm, 85 mm, 87 mm, 89 mm, 90 mm, 92 mm, 93 mm, or 94 mm; and the value of w / h3 can be 0.17, 0.19, 0.2, 0.22, 0.24, 0.26, or 0.28.

[0092] Specifically, if the w / h3 ratio is too small, the width of the limiting part 22 along the length of the battery pack will be small, and the height of the support beam 4 will be high. Since the limiting part 22 is the component that directly bears the load of the mounting component, a small width of the limiting part 22 is not conducive to dispersing the force. Excessive force concentration will cause the components inside the battery pack to be crushed. If the height of the support beam 4 is too high, the center of gravity of the battery pack will be high, resulting in poor overall stability of the battery pack. If the w / h3 ratio is too large, the width of the limiting part 22 along the length of the battery pack will be large, so that the limiting part 22 can distribute the force to the components of the battery pack such as the support beam 4, the partition 5, and the battery pack 3, making the battery pack structure more stable. However, if the height of the support beam 4 is too low, the lifting cylinder 2 cannot be completely hidden in the first cavity 42, which will affect the heat insulation between the lifting cylinder 2 and the first battery 31, thus failing to ensure uniform temperature of the battery pack 3 and making it difficult to guarantee the performance and service life of the battery pack.

[0093] In some embodiments, a support plate is provided between the limiting part 22 and the first battery 31, which can further disperse the load force and make the battery pack structure more stable.

[0094] Preferably, the support plate is a heat exchange plate 6, the battery pack 3 is pressed on the heat exchange plate 6, and the distance between the hoisting cylinder 2 and the inner wall of the first cavity 42 facing away from the first battery 31 is d mm, wherein 7 mm ≤ d ≤ 9.5 mm.

[0095] Due to the arrangement of the heat exchange plate 6, the first battery 31 of the battery pack 3 can exchange heat through the heat exchange plate 6. In order to avoid excessive heat loss from the first battery 31, the distance d between the lifting cylinder 2 and the inner wall of the first cavity 42 facing away from the first battery 31 needs to be increased, and kept at 7mm≤d≤9.5mm, so as to avoid more heat loss through the through hole 21 of the lifting cylinder 2. In addition, the distance d between the lifting cylinder 2 and the inner wall of the first cavity 42 facing away from the first battery 31 should not be too large, so as to avoid occupying too much space and affecting the energy density of the battery pack.

[0096] In one embodiment, the heat exchange plate 6 is disposed within the accommodating cavity 11 of the outer casing 1 and pressed onto the bottom plate 121 of the outer casing 1. The limiting part 22 is located between the heat exchange plate 6 and the bottom plate 121 of the outer casing 1 to disperse the load force and make the battery pack structure more stable.

[0097] In another embodiment, the bottom of the heat exchange plate 6 is thickened along the height direction of the battery pack to serve as the base plate 121 of the outer casing 1. The limiting part 22 is located at the bottom outside the outer casing 1 and supported on the bottom of the heat exchange plate 6, so as to disperse the load force and make the battery pack more stable.

[0098] In some embodiments, the support plate is the bottom plate 121 of the outer casing 1, and the limiting part 22 is located at the bottom outside the outer casing 1 and supported on the bottom of the bottom plate 121 of the outer casing 1, so as to disperse the load force and stabilize the structure of the battery pack.

[0099] In some embodiments, the outer casing 1 includes a housing 12 and a cover 13. The upper part of the housing 12 is provided with an opening. The housing 12 includes a bottom plate 121 and a frame 122. The frame 122 surrounds the outer periphery of the bottom plate 121. The cover 13 covers the opening of the housing 12. The accommodating cavity 11 is formed between the bottom plate 121 and the frame 122.

[0100] The lifting cylinder 2 includes a first lifting cylinder 23 and a second lifting cylinder 24 arranged sequentially along a first direction. The first lifting cylinder 23 is located between the support beam 4 and the cover 13, and the two ends of the first lifting cylinder 23 are connected to the opposite sides of the cover 13 and the support beam 4. The second lifting cylinder 24 passes through the support beam 4 along the first direction. One end of the second lifting cylinder 24 is connected to the bottom plate 121 of the housing 12, and the other end of the second lifting cylinder 24 is sealed to the first lifting cylinder 23.

[0101] In the first direction, the height of the second lifting cylinder 24 is a mm, and the height of the first lifting cylinder 23 is b mm, where 40 ≤ (a / b)*z ≤ 77.9, 100 mm ≤ a ≤ 110 mm, and 27 mm ≤ b ≤ 40 mm. Specifically, the value of a can be 101 mm, 102 mm, 104 mm, 106 mm, 108 mm, or 109 mm; the value of b can be 28 mm, 30 mm, 32 mm, 34 mm, 35 mm, 37 mm, 38 mm, or 39 mm; and the value of (a / b)*z can be 42, 45, 48, 50, 52, 54, 55, 58, 60, 62, 64, 66, 68, 70, 71, 73, 75, 76, or 77.

[0102] Since the mounting component penetrates through the first lifting cylinder 23 and the second lifting cylinder 24, and the lower end of the mounting component is supported at the lower end of the second lifting cylinder 24, the second lifting cylinder 24 is the main load-bearing component. The weight of the battery pack is mainly borne on the second lifting cylinder 24. Therefore, the larger a / b is, the greater the height of the second lifting cylinder 24 relative to the first lifting cylinder 23, and the greater the load-bearing capacity of the second lifting cylinder 24. Thus, reducing the inner diameter z of the through hole 21 can also ensure the lifting strength of the battery pack. Therefore, by keeping 40≤(a / b)*z≤77.9, and comprehensively considering the height a of the second lifting cylinder 24, the height b of the first lifting cylinder 23, and the inner diameter z of the through hole 21, the lifting cylinder 2 can have suitable lifting strength.

[0103] Preferably, the lifting cylinder 2 further includes a third lifting cylinder 25, which is sleeved on the outer side of the end of the first lifting cylinder 23 away from the second lifting cylinder 24, and the first lifting cylinder 23 and the third lifting cylinder 25 are threadedly connected. The end of the third lifting cylinder 25 away from the first lifting cylinder 23 is located outside the outer shell 1 and abuts against the upper end face of the cover 13.

[0104] The lifting cylinder 2 includes a first lifting cylinder 23, a second lifting cylinder 24, and a third lifting cylinder 25 connected together. Since the first lifting cylinder 23 is located inside the outer shell 1, a third lifting cylinder 25 is provided to facilitate the fixing of the upper end of the first lifting cylinder 23. The lower end of the third lifting cylinder 25 is inserted into the outer shell 1 and threadedly connected and fixed to the first lifting cylinder 23 to maintain the stability of both. Then, the upper end of the third lifting cylinder 25 abuts against the upper end face of the cover 13, so that the lifting cylinder 2 can be firmly fixed on the battery pack body, and it is also easy to ensure the sealing between the lifting cylinder 2 and the battery pack body.

[0105] In some embodiments, the outer casing 1 includes a housing 12 and a cover 13. The upper part of the housing 12 is provided with an opening. The housing 12 includes a bottom plate 121 and a frame 122. The frame 122 surrounds the outer periphery of the bottom plate 121. The cover 13 covers the opening of the housing 12. The accommodating cavity 11 is formed between the bottom plate 121 and the frame 122.

[0106] The lifting cylinder 2 includes a first lifting cylinder 23 and a second lifting cylinder 24 arranged sequentially along a first direction. One end of the first lifting cylinder 23 is connected to the cover 13, and the other end of the first lifting cylinder 23 extends into the support beam 4 along the first direction. The second lifting cylinder 24 passes through the support beam 4 along the first direction. One end of the second lifting cylinder 24 is connected to the bottom plate 121 of the housing 12, and the other end of the second lifting cylinder 24 is sleeved outside the end of the first lifting cylinder 23 that extends into the support beam 4. The first lifting cylinder 23 and the second lifting cylinder 24 are threadedly connected.

[0107] In the first direction, the height of the support beam 4 is h3mm, where 0.15≤z / h3≤0.3. Specifically, the value of z / h3 can be 0.16, 0.18, 0.2, 0.22, 0.24, 0.25, 0.27, 0.28 or 0.29.

[0108] After the battery pack is mounted on the vehicle body, vibrations will occur during vehicle operation. These vibrations will be transmitted to the battery pack, causing it to vibrate as well. Since the main load-bearing component of the battery pack is the mounting cylinder 2, and the mounting cylinder 2 is located at the support beam 4, the support beam 4 is significantly affected by vibrations. The higher the support beam 4 is, the greater the risk of deformation. To distribute the force more evenly and reduce the risk of deformation of the support beam 4, the size of the mounting component can be increased, that is, the inner diameter z of the through hole 21 can be increased. Therefore, by keeping 0.15 ≤ z / h3 ≤ 0.3, the ratio of the inner diameter z of the through hole 21 to the height h3 of the support beam 4 is kept within a certain range, which helps to improve the stability of the battery pack mounting.

[0109] In some embodiments, in a first direction, the second lifting cylinder 24 extends upward through the support beam 4 on the side opposite the cover 13, and the second lifting cylinder 24 is sealed to the first lifting cylinder 23. In the first direction, the height of the support beam 4 is h3mm, where 0.2≤a / h3≤0.6. Specifically, the value of a / h3 can be 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.54, 0.56, 0.58, or 0.59.

[0110] Specifically, the first lifting cylinder 23 and the second lifting cylinder 24 are threaded together to achieve a seal between them. Since the second lifting cylinder 24 extends upward through the upper end face of the support beam 4, if the dimension of the second lifting cylinder 24 along the height direction of the battery pack is too small, the threaded connection between the first lifting cylinder 23 and the second lifting cylinder 24 will be difficult. Moreover, if the height of the support beam 4 is too high, it will cause the center of gravity to be too high, resulting in the instability of the battery pack structure. Therefore, 0.2≤a / h3≤0.6 is maintained to facilitate the assembly of the lifting cylinder 2 and ensure the stability of the battery pack.

[0111] In some embodiments, the lifting cylinder 2 further includes a third lifting cylinder 25, which is disposed inside the end of the first lifting cylinder 23 away from the second lifting cylinder 24, and the first lifting cylinder 23 and the third lifting cylinder 25 are threadedly connected. The end of the third lifting cylinder 25 away from the first lifting cylinder 23 is located outside the outer casing 1 and abuts against the upper end face of the cover 13.

[0112] That is, after the third lifting cylinder 25 passes through the first lifting cylinder 23 and is threadedly connected to the first lifting cylinder 23, the third lifting cylinder 25 abuts against the upper end face of the cover 13, and the first lifting cylinder 23 abuts against the lower end face of the cover 13. The first lifting cylinder 23 and the third lifting cylinder 25 together clamp the cover 13, so that the lifting cylinder 2 can be stably installed on the battery pack and the installation is faster.

[0113] In some embodiments, the outer casing 1 includes a housing 12 and a cover 13. The upper part of the housing 12 is provided with an opening. The housing 12 includes a bottom plate 121 and a frame 122. The frame 122 surrounds the outer periphery of the bottom plate 121. The cover 13 covers the opening of the housing 12. The accommodating cavity 11 is formed between the bottom plate 121 and the frame 122.

[0114] An explosion-proof valve 313 is provided on the side of the first battery 31 facing the base plate 121. A weak part 123 is formed on the base plate 121 corresponding to the position of the explosion-proof valve 313. The distance between the weak part 123 and the lifting cylinder 2 is c mm, where 240 ≤ c*z ≤ 760. Specifically, the value of c*z can be 250, 280, 300, 320, 350, 380, 400, 430, 450, 480, 500, 530, 550, 580, 600, 620, 650, 670, 690, 700, 720, 740 or 750.

[0115] When the explosion-proof valve 313 bursts open and breaks through the weak part 123, the structural strength of the base plate 121 will weaken. Moreover, the lifting cylinder 2 is the main load-bearing component of the battery pack. Therefore, if the weak part 123 is too close to the lifting cylinder 2, it will affect the stability of the battery pack. At the same time, the larger the inner diameter z of the through hole 21 of the lifting cylinder 2, the larger the hanging component, the more dispersed the force, and the more stable the battery pack. Therefore, by comprehensively considering the distance between the weak part 123 and the lifting cylinder 2 and the inner diameter z of the through hole 21 of the lifting cylinder 2, 240≤c*z≤760 is maintained to ensure the stability of the battery pack structure.

[0116] In some embodiments, the distance between the weak part 123 and the lifting cylinder 2 is c mm, where 15 mm ≤ c ≤ 40 mm. Specifically, the value of c can be 17 mm, 19 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, 32 mm, 34 mm, 35 mm, 37 mm, 38 mm, and 39 mm.

[0117] If the distance c between the weak part 123 and the hoisting cylinder 2 is too small, the structural strength of the hoisting cylinder 2 will be affected after the explosion-proof valve 313 bursts. If the distance c between the weak part 123 and the hoisting cylinder 2 is too large, it will not be conducive to improving the utilization rate of the space inside the battery pack. Therefore, it is necessary to keep 15mm≤c≤40mm in order to improve the space utilization rate while ensuring the structural strength of the hoisting cylinder 2.

[0118] In some embodiments, the distance between the weak portion 123 and the limiting portion 22 of the hoisting cylinder 2 is e mm, where 5 mm ≤ e ≤ 20 mm. Specifically, the value of e can be 6 mm, 7 mm, 9 mm, 10 mm, 12 mm, 14 mm, 16 mm, 17 mm, 18 mm, or 19 mm.

[0119] If the distance e between the weak part 123 and the limiting part 22 is too small, it will affect the structural strength of the hoisting cylinder 2 after the explosion-proof valve 313 bursts. If the distance e between the weak part 123 and the limiting part 22 is too large, it will not be conducive to improving the utilization rate of the space inside the battery pack. Therefore, it is necessary to keep 5mm≤e≤20mm in order to improve the space utilization rate while ensuring the structural strength of the hoisting cylinder 2.

[0120] It should be noted that the bottom plate 121 of the battery pack and the area corresponding to the explosion-proof valve 313 of the first battery 31 are scratched to weaken the structural strength of the area, thereby forming the weak part 123. Alternatively, a groove is provided on the bottom plate 121 of the battery pack to weaken the structural strength and form the weak part 123.

[0121] In some embodiments, the weight of the battery pack body is g / kg, where g > 160 kg and 0.6 ≤ y / z ≤ 1.5. Specifically, the value of g can be 170 kg, 190 kg, 200 kg, 220 kg, 240 kg, 250 kg, 270 kg, 290 kg, or 300 kg.

[0122] Since the heavier the battery pack body, the more battery packs 3 are inside the battery pack body, the higher the requirements for the load-bearing capacity of the mounting components and the uniform temperature of the battery pack. Therefore, it is necessary to maintain 0.6≤y / z≤1.5.

[0123] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A battery pack having two perpendicular directions: a first direction, a second direction, and a third direction, characterized in that, Includes a battery pack body, the battery pack body comprising: The outer casing has an internal cavity. A lifting cylinder extends through the upper and lower sidewalls of the outer casing along a first direction, and the two ends of the lifting cylinder along the axial direction are connected to the upper and lower sidewalls of the outer casing respectively. A through hole is formed inside the lifting cylinder along the axial direction. A battery pack is disposed within the accommodating cavity. The battery pack includes multiple individual cells, and among the multiple individual cells, the individual cell closest to the hoisting cylinder is the first cell. Wherein, the distance between the first battery and the hoisting cylinder is y, in mm, and the inner diameter of the through hole is z, in mm, where 0.6≤y / z≤1.5, 11.5mm≤y≤23.5mm, and 16mm≤z≤19mm.

2. The battery pack according to claim 1, characterized in that, It also includes a support beam, which is disposed within the accommodating cavity and extends along a second direction. The battery pack is provided on both sides of the support beam in a third direction, and the hoisting cylinder at least partially penetrates the support beam along a first direction.

3. The battery pack according to claim 2, characterized in that, The support beam is provided with multiple reinforcing ribs, and the multiple reinforcing ribs form multiple first cavities in the support beam. The hoisting cylinder is located in one of the first cavities, and there is a gap between the outer side of the hoisting cylinder and the inner side of the first cavity.

4. The battery pack according to claim 2, characterized in that, The distance between the support beam and the first battery on the side facing the first battery is M, in mm, where 0.26 ≤ (yM) / z ≤ 0.

6.

5. The battery pack according to claim 3, characterized in that, The distance between the hoisting cylinder and the inner wall of the first cavity opposite to the first battery is d, in mm, where 5mm≤d≤9.5mm.

6. The battery pack according to claim 3, characterized in that, The distance between the hoisting cylinder and the support beam on one side in the third direction is the same as the distance between the hoisting cylinder and the support beam on the other side in the third direction.

7. The battery pack according to claim 1, characterized in that, The thickness of the sidewall of the hoisting cylinder is T1, in mm, where 2≤z / T1≤5.

5.

8. The battery pack according to claim 7, characterized in that, 3.5mm≤T1≤8mm.

9. The battery pack according to claim 3, characterized in that, It also includes a separator, which is disposed between the support beam and the first battery. The thermal conductivity of the separator is k1, with units of W / (mK), wherein k1≤0.46W / (mK).

10. The battery pack according to claim 9, characterized in that, 0.7≤y / z≤1.

1.

11. The battery pack according to claim 9, characterized in that, In the first direction, the partition extends upward beyond the upper end face of the support beam, wherein 0.65≤y / z≤0.

95.

12. The battery pack according to claim 11, characterized in that, In the first direction, the separator extends upward beyond the upper surface of the first battery, 0.6≤y / z≤0.

68.

13. The battery pack according to claim 9, characterized in that, In the third direction, the thickness of the partition is T2, in mm, where 5mm≤T2≤13mm.

14. The battery pack according to claim 9, characterized in that, The partition plate has multiple protruding ribs on the side facing the support beam, and the protruding ribs abut against the support beam. Multiple second cavities are formed between the multiple protruding ribs, the partition plate, and the support beam.

15. The battery pack according to claim 14, characterized in that, The second cavity is provided with a fixing adhesive layer, and the partition is fixed to the support beam through the fixing adhesive layer.

16. The battery pack according to claim 15, characterized in that, 16mm≤z≤17mm.

17. The battery pack according to claim 14, characterized in that, At least one of the protruding ribs and the reinforcing ribs in the support beam are staggered, and the wall thickness of the support beam is T3 in mm, wherein T3 ≥ 2 mm.

18. The battery pack according to claim 14, characterized in that, The multiple reinforcing ribs in the support beam are arranged one-to-one with the multiple protruding ribs on the partition.

19. The battery pack according to claim 14, characterized in that, The interior of the first cavity and / or the second cavity is filled with a heat-insulating medium.

20. The battery pack according to claim 9, characterized in that, A buffer is provided between the separator and the first battery.

21. The battery pack according to claim 20, characterized in that, In the third direction, the thickness of the buffer is T4, in mm, where 1.5mm ≤ T4 ≤ 4mm.

22. The battery pack according to claim 1, characterized in that, A connecting adhesive layer is provided between the hoisting cylinder and the first battery. The thermal conductivity of the connecting adhesive layer is k2, with units of W / (mK), where k2≤0.8W / (mK).

23. The battery pack according to claim 2, characterized in that, The largest side of the first battery faces the supporting beam, where 0.6 ≤ y / z ≤ 1.

1.

24. The battery pack according to claim 23, characterized in that, The first battery includes a housing and a battery cell. The battery cell is disposed in the housing. In a first direction, the height of the battery cell is h1 in mm, and the height of the housing is h2 in mm, wherein h1 / h2≤0.

98.

25. The battery pack according to claim 9, characterized in that, The lower end of the hoisting cylinder extends in a third direction to form a limiting part, and the limiting part extends beyond the side of the support beam opposite the first battery.

26. The battery pack according to claim 25, characterized in that, The limiting portion extends in a third direction and beyond the side of the separator opposite the first battery.

27. The battery pack according to claim 26, characterized in that, The projection of the limiting part in the first direction overlaps with the projection of the first battery in the first direction.

28. The battery pack according to claim 25, characterized in that, In the third direction, the width of the limiting part is w in mm, and in the first direction, the height of the supporting beam is h3 in mm, where 0.15 ≤ w / h3 ≤ 0.

29.

29. The battery pack according to claim 25, characterized in that, A support plate is provided between the limiting part and the first battery.

30. The battery pack according to claim 29, characterized in that, The support plate is a heat exchange plate, and the distance between the hoisting cylinder and the inner wall of the first cavity opposite to the first battery is d, in mm, wherein 7mm≤d≤9.5mm.

31. The battery pack according to claim 2, characterized in that, The outer casing includes a shell and a cover. The upper part of the shell has an opening. The shell includes a bottom plate and a frame. The frame surrounds the outer periphery of the bottom plate. The cover covers the opening of the shell. The bottom plate and the frame form the receiving cavity. The lifting cylinder includes a first lifting cylinder and a second lifting cylinder arranged sequentially along a first direction. The first lifting cylinder is located between the support beam and the cover, and the two ends of the first lifting cylinder are connected to the opposite sides of the cover and the support beam. The second lifting cylinder passes through the support beam along the first direction. One end of the second lifting cylinder is connected to the bottom plate of the shell, and the other end of the second lifting cylinder is sealed to the first lifting cylinder. In the first direction, the height of the second cylinder is a in mm, and the height of the first cylinder is b in mm, where 40 ≤ (a / b) * z ≤ 77.

9.

32. The battery pack according to claim 2, characterized in that, The outer casing includes a shell and a cover. The upper part of the shell has an opening. The shell includes a bottom plate and a frame. The frame surrounds the outer periphery of the bottom plate. The cover covers the opening of the shell. The bottom plate and the frame form the receiving cavity. The lifting cylinder includes a first lifting cylinder and a second lifting cylinder arranged sequentially along a first direction. One end of the first lifting cylinder is connected to the cover body, and the other end of the first lifting cylinder extends into the support beam along the first direction. The second lifting cylinder passes through the support beam along the first direction. One end of the second lifting cylinder is connected to the bottom plate of the shell, and the other end of the second lifting cylinder is sleeved outside the end of the first lifting cylinder that extends into the support beam. The first lifting cylinder and the second lifting cylinder are threaded together. In the first direction, the height of the support beam is h3, in mm, where 0.15 ≤ z / h3 ≤ 0.

3.

33. The battery pack according to claim 31, characterized in that, The lifting cylinder also includes a third lifting cylinder, which is sleeved on the outside of the end of the first lifting cylinder away from the second lifting cylinder, and the first lifting cylinder and the third lifting cylinder are threaded together. The end of the third lifting cylinder away from the first lifting cylinder is located outside the outer shell and abuts against the upper surface of the cover.

34. The battery pack according to claim 31, characterized in that, In the first direction, the second lifting cylinder extends upward through the side of the support beam opposite the cover, and the second lifting cylinder is sealed to the first lifting cylinder; In the first direction, the height of the support beam is h3, in mm, where 0.2 ≤ a / h3 ≤ 0.

6.

35. The battery pack according to claim 31, characterized in that, The lifting cylinder also includes a third lifting cylinder, which is inserted inside the end of the first lifting cylinder away from the second lifting cylinder, and the first lifting cylinder and the third lifting cylinder are threadedly connected.

36. The battery pack according to claim 25, characterized in that, The outer casing includes a shell and a cover. The upper part of the shell has an opening. The shell includes a bottom plate and a frame. The frame surrounds the outer periphery of the bottom plate. The cover covers the opening of the shell. The bottom plate and the frame form the receiving cavity. An explosion-proof valve is provided on the side of the first battery facing the base plate. A weak part is formed on the base plate corresponding to the position of the explosion-proof valve. The distance between the weak part and the hoisting cylinder is c, in mm, where 240≤c*z≤760.

37. The battery pack according to claim 36, characterized in that, 15mm≤c≤40mm.

38. The battery pack according to claim 36, characterized in that, The distance between the weak part and the limiting part of the hoisting cylinder is e, in mm, where 5mm≤e≤20mm.

39. The battery pack according to claim 1, characterized in that, The weight of the battery pack body is in g, and the unit is kg, where g > 160 kg and 0.6 ≤ y / z ≤ 1.5.

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