Battery pack lower box body and battery pack

Abstract

The utility model provides a battery pack lower box body and a battery pack. The utility model relates to a lower box body of a battery pack, which comprises a main body frame assembled at the top end of a bottom protective plate, the main body frame is provided with a vertically through electrical part accommodating cavity, and the lower box body of the battery pack further comprises a first reinforcing part fixedly connected to the bottom end of the cavity wall of the electrical part accommodating cavity to seal the lower part of the electrical part accommodating cavity; the second reinforcing part is fixedly connected to two opposite cavity walls of the electrical part accommodating cavity and is fixedly connected with the first reinforcing part; when the bottom protection plate extrudes the first reinforcing part due to upward impact force, the first reinforcing part and the second reinforcing part jointly form a support for the bottom protection plate in the vertical direction. According to the lower box body of the battery pack disclosed by the utility model, the second reinforcing part is connected with the first reinforcing part and the cavity wall of the electrical part accommodating cavity, so that the bottom protection plate corresponding to the electrical part accommodating cavity is not easy to deform excessively, the overall rigidity of the battery pack is improved, and the sealing stability of the bottom protection plate is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power batteries, and particularly relates to a lower box body of a battery pack. The utility model also relates to a battery pack equipped with the above-mentioned lower box body of the battery pack. Background Art

[0002] With the increasing global attention to renewable energy and green travel, the new energy industry is experiencing unprecedented high-speed development. As a key energy storage device, the battery pack has become the focus of research and development in various related industries. The battery pack not only bears the important responsibility of providing continuous power for equipment, but also faces the challenges of various complex working conditions and extreme environments that may be encountered in actual use.

[0003] The specific structural design of the battery pack is also constantly improved and optimized, because the overall structure of the battery pack is directly related to its safety and stability during use. Conventional battery packs usually include a top cooling plate, battery modules, electrical components, a lower box body, a bottom guard plate, etc. The battery modules are installed inside the lower box body, and the battery cells in the battery modules are the main body for storing electrical energy. The top cooling plate is installed at the top of the lower box body, and the battery cells in the battery modules are cooled by circulating coolant to ensure that the battery cells will not be damaged due to overheating during operation. The electrical components are the bridge connecting the battery modules and the external system, and are usually installed at one end inside the lower box body and connected to the battery modules and the external system through cables and connectors. The part of the lower box body corresponding to the installation of the electrical components is usually set as an independent chamber for accommodating most of the electrical components and providing necessary protection and isolation. The bottom guard plate is installed at the bottom of the battery pack to play a role in sealing and protection.

[0004] During the actual use of the battery pack, since the battery modules themselves have a certain structural strength, they can provide a certain degree of support and reinforcement for the bottom guard plate. When the bottom guard plate is impacted, the part of the bottom guard plate corresponding to the installation of the electrical components receives less support and is more likely to be damaged and deformed, affecting the overall stiffness of the battery pack. Summary of the Utility Model

[0005] In view of this, the utility model aims to propose a structure of the lower box body of the battery pack to improve the overall stiffness of the battery pack.

[0006] To achieve the above object, the technical solution of the utility model is realized as follows:

[0007] A lower box body of a battery pack includes a main frame assembled on the top end of a bottom guard plate. The main frame is provided with a vertically penetrating electrical component accommodating cavity. The lower box body of the battery pack further includes:

[0008] A first strengthening part, fixedly connected to the bottom end of the cavity wall of the electrical component accommodating cavity, forming a lower closure of the electrical component accommodating cavity;

[0009] A second reinforcing part, fixedly connected between the cavity wall of the electrical component accommodating cavity and the first reinforcing part;

[0010] When the bottom guard plate is squeezed against the first reinforcing part due to an upward impact force, the first reinforcing part and the second reinforcing part jointly constitute a support for the bottom guard plate in the vertical direction.

[0011] Furthermore, the bottom guard plate is provided with upwardly protruding reinforcing ribs; at least two reinforcing protrusions are convexly provided at the bottom end of the first reinforcing part, the reinforcing protrusions abut against the bottom guard plate, and a receiving space for receiving the reinforcing ribs is formed between two adjacent reinforcing protrusions.

[0012] Furthermore, the first reinforcing part is a hollow plate member penetrating in the horizontal direction, and a reinforcing rib plate is fixedly connected between the upper inner wall and the lower inner wall of the hollow plate member.

[0013] Furthermore, there are a plurality of the reinforcing rib plates, and every two of the reinforcing rib plates form a group to form an "eight" - shaped structure.

[0014] Furthermore, the length of the hollow plate member is A, and the distance D between two adjacent groups of the reinforcing rib plates is 0.04A - 0.05A.

[0015] Furthermore, the included angle between the reinforcing rib plate and the lower inner wall of the hollow plate member is 45° - 60°.

[0016] Furthermore, the length of the hollow plate member is A, and the wall thickness t of the hollow plate member is 0.002A - 0.003A.

[0017] Furthermore, the height of the electrical component accommodating cavity is Z, the second reinforcing part is a rectangular tube extending in the horizontal direction, and the height b of the rectangular tube is 0.3Z - 0.4Z; and / or,

[0018] The height of the electrical component accommodating cavity is Z, and the height G of the first reinforcing part is 0.3Z - 0.4Z.

[0019] Furthermore, a gap is provided between the edge of the first reinforcing part and the cavity wall of the electrical component accommodating cavity, and the gap is 1 mm - 2 mm.

[0020] Compared with the prior art, the present utility model has the following advantages:

[0021] For the lower battery box of the present utility model, a first reinforcing part is provided at the bottom of the electrical component receiving cavity. When the bottom guard plate is impacted upward, it can support the bottom guard plate, making it not easy for the bottom guard plate corresponding to the electrical component receiving cavity to deform excessively, improving the overall stiffness of the battery pack and enhancing the sealing stability of the bottom guard plate. A second reinforcing part is connected to the first reinforcing part and the cavity wall of the electrical component receiving cavity, which can assist the first reinforcing part in supporting the bottom guard plate and improve the structural strength of the battery pack.

[0022] Setting reinforcing ribs on the bottom guard plate is a common way to enhance the bottom guard plate. Setting reinforcing protrusions can enable the first reinforcing part to avoid the reinforcing ribs, and directly contact the bottom plate through the reinforcing protrusions to reduce the contact area and improve the force transmission effect.

[0023] The first reinforcing part is set as a hollow plate member, and reinforcing rib plates are fixedly connected between its upper inner wall and lower inner wall, which can reduce the weight of the first reinforcing part and is beneficial to the lightweight design of the battery pack. At the same time, setting the reinforcing rib plates also enables the first reinforcing part to have better structural strength.

[0024] The reinforcing rib plates are set in groups to form an "eight" - shaped structure, which can enable the first reinforcing part to have better supporting strength in the vertical direction and transmit the force obliquely upward at the same time.

[0025] The distance between adjacent two groups of reinforcing rib plates is set to be 0.04A - 0.05A, which can not only ensure the structural strength of the first reinforcing part but also use less materials and have lower costs.

[0026] Setting an angle of 45° - 60° between the reinforcing rib plates and the hollow plate member can enable the reinforcing rib plates to have better force - transmission effects and enhance the structural strength of the first reinforcing part.

[0027] Setting the wall thickness of the hollow plate member to be 0.002A - 0.003A can not only ensure the strength of the hollow plate member but also make the manufacturing cost of the hollow plate member relatively low.

[0028] The second reinforcing part is set as a rectangular pipe, which has better structural strength and the production raw materials are also easy to obtain. Limiting the height of the second reinforcing part can also enable the second reinforcing part to have better structural strength while not overly occupying the space of the electrical component receiving cavity. Limiting the height of the first reinforcing part enables the first reinforcing part to have better structural strength while not overly occupying the space of the electrical component receiving cavity.

[0029] Setting a gap between the first reinforcing part and the cavity wall of the electrical component receiving cavity can facilitate the installation of the first reinforcing part on the frame body. At the same time, setting the size to be 1mm - 2mm will not make the gap too large to affect the welding between the first reinforcing part and the frame body.

[0030] Another object of the present utility model is to propose a battery pack, which is equipped with the above - mentioned lower battery box of the battery pack.

[0031] The battery pack described in the present utility model has the same beneficial effects as the lower box body of the battery pack described above with respect to the prior art, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings forming a part of the present utility model are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0033] Figure 1 is an exploded view of the connection relationship between the lower box body of the battery pack and the bottom guard plate in the first embodiment of the present utility model;

[0034] Figure 2 is a schematic structural view of the first reinforcing part and the second reinforcing part in the first embodiment of the present utility model;

[0035] Figure 3 is a front view of the first reinforcing part and the second reinforcing part in the first embodiment of the present utility model;

[0036] Figure 4 is Figure 3 a partial enlarged view of the X part in

[0037] Figure 5 is a right view of the first reinforcing part and the second reinforcing part in the first embodiment of the present utility model;

[0038] Figure 6 is an exploded view of the assembly position of the lower box body of the battery pack in the battery pack in the first embodiment of the present utility model.

[0039] Description of the reference numerals:

[0040] 1. Main body frame;

[0041] 101. Electrical component receiving cavity; 102. First reinforcing part; 1021. Reinforcing protrusion; 1022. Reinforcing rib plate; 103. Second reinforcing part; 104. Receiving space; 105. Side beam; 106. Front beam; 107. Cross beam; 108. Rear beam;

[0042] 2. Bottom guard plate;

[0043] 201. Reinforcing rib;

[0044] 3. Cold plate;

[0045] 4. Battery module;

[0046] 5. Electrical component. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0048] In the description of the present utility model, it should be noted that if terms indicating orientation or positional relationship such as "upper", "lower", "inner", "outer", etc. appear, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present utility model. In addition, if terms such as "first", "second", etc. appear, they are also only for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0049] In addition, in the description of the present utility model, unless otherwise clearly defined, the terms "installation", "connection", "connection", "connector" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood in combination with specific situations.

[0050] The present utility model will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0051] Embodiment 1

[0052] This embodiment relates to a lower box body of a battery pack, in order to enhance the supporting ability of the lower box body of the battery pack for the bottom guard plate 2 and improve the overall structural stiffness of the battery pack.

[0053] In terms of the overall structure, the lower box body of the battery pack in this embodiment includes a main frame 1 assembled at the top end of the bottom guard plate 2. The main frame 1 is provided with a vertically penetrating electrical component receiving cavity 101. The lower box body of the battery pack further includes: a first strengthening part 102 fixedly connected to the bottom end of the cavity wall of the electrical component receiving cavity 101 to form the lower closure of the electrical component receiving cavity 101. A second strengthening part 103 fixedly connected between the cavity wall of the electrical component receiving cavity 101 and the first strengthening part 102. When the bottom guard plate 2 is pressed against the first strengthening part 102 due to an upward impact force, the first strengthening part 102 and the second strengthening part 103 jointly constitute the support for the bottom guard plate 2 in the vertical direction.

[0054] With the above settings, for the lower case of the battery pack in this embodiment, a first reinforcing portion 102 is provided at the bottom of the electrical component receiving cavity 101. When an upward impact is applied to the bottom guard plate 2 in this area, it can support the bottom guard plate 2, making it difficult for the bottom guard plate 2 corresponding to the electrical component receiving cavity 101 to be excessively deformed, improving the overall stiffness of the battery pack, and enhancing the sealing stability of the bottom guard plate 2. A second reinforcing portion 103 is provided to be connected to the first reinforcing portion 102 and the cavity wall of the electrical component receiving cavity 101, which can assist the first reinforcing portion 102 in supporting the bottom guard plate 2 and improving the structural strength of the battery pack.

[0055] Based on the above overall introduction, referring to Figures 1 to 6 , specifically, the main frame 1 includes a front side beam 106, a rear side beam 108, side beams 105, and a cross beam 107. For the convenience of description, the extending direction of the side beam 105 is defined as the length direction of the battery pack, the extending direction of the front side beam 106 is defined as the width direction of the battery pack, and the vertical direction is defined as the height direction of the battery pack. The front side beam 106, the rear side beam 108, and the two side beams 105 are welded to form a rectangular frame, and the cross beam 107 is welded between the two side beams 105 along the width direction of the battery pack. The cross beam 107 close to the front side beam 106, together with the front side beam 106 and the two side beams 105, constitutes the electrical component receiving cavity 101 for receiving the electrical components 5 in the battery pack. The battery module 4 is assembled within the main frame 1, and the cold plate 3 is assembled at the top of the main frame 1 and contacts the battery cells of the battery module 4.

[0056] Generally, in order to enhance the strength of the bottom guard plate 2, reinforcing ribs 201 are provided on the bottom guard plate 2. Referring to Figure 1 and Figure 2 , to avoid interference between the reinforcing ribs 201 and the first reinforcing portion 102, at least two reinforcing protrusions 1021 are convexly provided at the bottom end of the first reinforcing portion 102. The reinforcing protrusions 1021 abut against the bottom guard plate 2, and a receiving space 104 for receiving the reinforcing ribs 201 is formed between two adjacent reinforcing protrusions 1021. Providing the reinforcing protrusions 1021 enables the first reinforcing portion 102 to avoid the reinforcing ribs 201, and by directly contacting the bottom plate through the reinforcing protrusions 1021, the contact area is reduced, improving the force transmission effect. In this embodiment, the reinforcing ribs 201 are provided as a ring of protrusions along the edge of the bottom guard plate 2 and a cross-shaped protrusion provided in the middle. Two reinforcing protrusions 1021 are provided, which are integrally formed with the first reinforcing portion 102 and respectively abut against the bottom guard plate 2 on both sides of the cross-shaped protrusion.

[0057] For the purpose of the strength quantification design of the lower case of the battery pack, referring to Figure 2 and Figure 3, the first reinforcing part 102 is a hollow plate member penetrating in the horizontal direction, and reinforcing rib plates 1022 are fixedly connected between the upper inner wall and the lower inner wall of the hollow plate member. Setting the first reinforcing part 102 as a hollow plate member and fixedly connecting the reinforcing rib plates 1022 between its upper inner wall and lower inner wall can reduce the weight of the first reinforcing part 102, which is beneficial to the lightweight design of the battery pack. At the same time, setting the reinforcing rib plates 1022 also gives the first reinforcing part 102 better structural strength. In this embodiment, the first reinforcing part 102 is formed by welding two mirror-image components.

[0058] Furthermore, there are multiple reinforcing rib plates 1022. Every two reinforcing rib plates 1022 form a group, forming a "V"-shaped structure. The reinforcing rib plates 1022 are set in groups to form a "V"-shaped structure, which can make the first reinforcing part 102 have better supporting strength in the vertical direction. When an external force acts on the first reinforcing part 102, the force can be transmitted obliquely upward, which is beneficial to the second reinforcing part 103 to exert its auxiliary supporting ability on the first reinforcing part 102.

[0059] To facilitate the connection between the first reinforcing part 102 and the main body frame 1, there is a gap between the edge of the first reinforcing part 102 and the cavity wall of the electrical component receiving cavity 101, and the gap is 1 mm to 2 mm. Setting a gap between the first reinforcing part 102 and the cavity wall of the electrical component receiving cavity 101 can facilitate the installation of the first reinforcing part 102 on the frame main body. At the same time, the size setting of 1 mm to 2 mm will not make the gap too large to affect the welding operation between the first reinforcing part 102 and the frame main body. In this embodiment, the preferred gap is 1.5 mm.

[0060] Regarding the specific structure of the second reinforcing part 103, a rectangular tube is used as the second reinforcing part 103 in this embodiment. Both ends of the rectangular tube are open and are respectively welded to the front side beam 106 and the cross beam 107, and the bottom end is welded to the top end of the first reinforcing part 102. The rectangular tube itself has good structural strength, and the raw materials for manufacturing are easy to obtain, and the manufacturing cost is low. The second reinforcing part 103 is arranged along the length direction of the battery pack, and six are arranged at intervals along the width direction of the battery pack.

[0061] To facilitate the description of the relevant dimensional characteristics of the lower box body in this embodiment, refer to Figures 3 to 5 , the length of the first reinforcing part 102 in the width direction of the battery pack is A, the length of one component of the first reinforcing part 102 is B, the total height including the reinforcing protrusion 1021 is G, and the width in the length direction of the battery pack is E. The length of the reinforcing protrusion 1021 in the width direction of the battery pack is C. There is a notch for avoiding the circumferential edge reinforcing rib 201 of the bottom guard plate 2, and the width of the notch in the length direction of the battery pack is F, and the height of the reinforcing protrusion 1021 is H.

[0062] Specifically, the width of the receiving space 104 for receiving the reinforcing rib 201 is 2(B - C). Since a chamfer is usually provided at the root of the reinforcing rib 201, an additional distance needs to be set to accommodate the rounded corner part. Therefore, the width 2(B - C) of the receiving space 104 ≥ the width of the reinforcing rib 201 + 2×5 mm, where 5 mm is the expansion made for accommodating the rounded corner part.

[0063] Regarding the specific setting angle of the reinforcing rib plate 1022, in order to improve its force transmission ability, the included angle between the reinforcing rib plate 1022 and the lower inner wall of the hollow plate member is 45° to 60°. Setting an included angle of 45° to 60° between the reinforcing rib plate 1022 and the hollow plate member can enable the reinforcing rib plate 1022 to have a better force transmission effect and improve the structural strength of the first reinforcing part 102. When the setting angle is less than 45°, the reinforcing rib plate 1022 is longer and its supporting ability in the vertical direction is lacking; when the setting angle is greater than 60°, the reinforcing rib plate 1022 is shorter and its function of inclined and dispersed force transmission is weaker. In this embodiment, the included angle between the reinforcing rib plate 1022 and the hollow plate member is preferably 50°. Rounded corners are provided at the joints between the reinforcing rib plate 1022 and the upper inner wall of the hollow plate member and between the reinforcing rib plate 1022 and the lower inner wall of the hollow plate member, which can enhance the overall structural strength of the first reinforcing part 102. In addition, the reinforcing protrusion 1021 is a "U" - shaped frame with an opening connecting the first reinforcing part 102, and a plurality of reinforcing plates in the same extending direction as the reinforcing rib plate 1022 are provided between the reinforcing protrusion 1021 and the first reinforcing part 102, which can also achieve the effect of weight reduction and strengthening.

[0064] Regarding the setting quantity of the reinforcing rib plates 1022, it can be arranged according to actual needs. In this embodiment, the spacing D between two adjacent groups of reinforcing rib plates 1022 = 0.04A to 0.05A. If the spacing between two adjacent groups of reinforcing rib plates 1022 is less than 0.04A, the reinforcing rib plates 1022 are too dense, which is not conducive to lightweight design; if the spacing between two adjacent groups of reinforcing rib plates 1022 is greater than 0.05A, the reinforcing rib plates 1022 are too sparse and the overall strength of the first reinforcing part 102 is lacking. In this embodiment, D = 0.045A is preferably selected, which can not only ensure the structural strength of the first reinforcing part 102 but also use less materials and have a lower cost.

[0065] In addition, for the wall thickness t of the hollow plate member, its numerical range is t = 0.002A to 0.003A. When t < 0.002A, the overall stiffness of the hollow plate member is poor; when t > 0.003A, the hollow plate member is overall heavier. In this embodiment, t = 0.0025A is preferably selected, which can not only ensure the strength of the hollow plate member but also make the manufacturing cost of the hollow plate member lower. Correspondingly, in order to facilitate the forming of the reinforcing rib plate 1022, the thickness of the reinforcing rib plate 1022 is equal to t.

[0066] In addition, let the height of the electrical component receiving cavity 101 be Z. To ensure that there is enough space in the electrical component receiving cavity 101 to accommodate the electrical component 5, the total height G of the first strengthening part 102 is 0.3Z to 0.4Z. In this embodiment, G = 0.35Z is preferably adopted. The first strengthening part 102 has good strength and occupies less space in the electrical component receiving cavity 101. The rectangular tube cross-section width of the second strengthening part 103 is b, the height is a, and the wall thickness of the tube is c, where b = 2a = 0.3Z to 0.4Z. In this embodiment, b = 0.35Z is preferably adopted. The second strengthening part 103 has good strength and occupies less space in the electrical component receiving cavity 101.

[0067] In this embodiment, by providing the first strengthening part 102 and the second strengthening part 103, the first strengthening part 102 and the second strengthening part 103 support the bottom protection plate 2, effectively improving the impact resistance of the bottom protection plate 2 corresponding to the electrical component receiving cavity 101, thereby improving the overall stiffness of the battery pack and also making the sealing stability of the bottom protection plate 2 at the lower housing better. The first strengthening part 102 and the second strengthening part 103 are designed with hollow structures, which also reduces the overall weight of the battery pack and the overall structure is relatively compact.

[0068] Embodiment 2

[0069] This embodiment relates to a battery pack equipped with the battery pack lower box body in Embodiment 1.

[0070] With the above settings, the battery pack in this embodiment has higher structural stiffness at the bottom. When subjected to external force impact, the bottom protection plate 2 is not easily deformed excessively, and the sealing stability of the bottom protection plate 2 for the bottom of the battery pack can be maintained. Secondly, when the battery pack is used in new energy vehicles, the battery pack has good ball impact performance, and the vehicle using the battery pack in this embodiment can have stronger environmental adaptability.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A battery pack lower box, comprising a main frame mounted on the top of a bottom guard plate, wherein the main frame is provided with a vertically penetrating electrical component accommodating cavity, characterized in that: The battery pack lower box also includes: A first reinforcement portion is fixedly connected to the bottom end of the cavity wall of the electrical component accommodating cavity to seal the lower part of the electrical component accommodating cavity; A second reinforcement portion, fixedly connected between the cavity wall of the electrical component accommodating cavity and the first reinforcement portion; When the bottom guard plate is subjected to an upward impact force and the first reinforcing portion is compressed, the first reinforcing portion and the second reinforcing portion together form a support for the bottom guard plate in the vertical direction; The first reinforcement part is a hollow plate member penetrating in the horizontal direction, and a reinforcement rib is fixedly connected between the upper inner wall and the lower inner wall of the hollow plate member.

2. The battery pack lower box according to claim 1, characterized in that: The bottom guard plate is provided with a reinforcing rib protruding upward; at least two reinforcing protrusions are protruding below the bottom end of the first reinforcing portion, the reinforcing protrusions abut against the bottom guard plate, and a receiving space for receiving the reinforcing rib is formed between two adjacent reinforcing protrusions.

3. The battery pack lower box according to claim 1, characterized in that: There are multiple reinforcing ribs, and every two reinforcing ribs form a group to form an "eight" shaped structure.

4. The battery pack lower box according to claim 3, characterized in that: The length of the hollow plate is A, and the distance between two adjacent groups of reinforcing ribs is D=0.04A-0.05A.

5. The battery pack lower box according to claim 1, characterized in that: The included angle between the reinforcing rib and the lower inner wall of the hollow plate is 45° to 60°.

6. The battery pack lower box according to claim 1, characterized in that: The length of the hollow plate is A, and the wall thickness of the hollow plate is t=0.002A-0.003A.

7. The battery pack lower box according to claim 1, characterized in that: The height of the electrical component accommodating cavity is Z, the second reinforcement portion is a rectangular tube extending in the horizontal direction, and the height of the rectangular tube is b=0.3Z-0.4Z; and / or, The height of the electrical component accommodating cavity is Z, and the height of the first reinforcement portion is G=0.3Z~0.4Z.

8. The battery pack lower box according to any one of claims 1 to 7, characterized in that: A gap is provided between the edge of the first reinforcement portion and the cavity wall of the electrical component accommodating cavity, and the gap is 1 mm to 2 mm.

9. A battery pack, characterized in that: The battery package is provided with a battery package lower box as described in any one of claims 1 to 8.

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