Battery pack

Abstract

The utility model relates to the technical field of batteries, in particular to a battery pack which comprises a battery box body and a cooling structure, the battery box body is provided with a cavity for accommodating a single battery, the battery box body comprises a bottom plate, and the bottom plate is provided with a bottom surface back to the cavity; the cooling structure comprises a cooling pipe, at least part of the cooling pipe is arranged on the bottom face, the cooling pipe is provided with a heat dissipation face facing the bottom plate, and at least part of the heat dissipation face makes contact with the bottom face. Wherein the area, with the orthographic projection of the single battery, of the bottom surface is a contact area, and the area of the part, making contact with the bottom surface, of the heat dissipation surface accounts for 30%-50% of the area of the contact area.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and particularly relates to a battery pack. Background Art

[0002] In the existing design scheme of the battery pack, some adopt the design of external cooling pipes, that is, the cooling pipes are arranged outside the battery box body. However, the above existing scheme has the problem that the cooling effect of the cooling pipes and the battery box body is poor, which affects the heat dissipation performance of the battery pack. Summary of the Utility Model

[0003] A main object of the utility model is to overcome at least one defect of the above existing technology, and provide a

[0004] To achieve the above object, the utility model adopts the following technical scheme:

[0005] According to one aspect of the utility model, a battery pack is provided, which includes a battery box body and a cooling structure; the battery box body has a cavity for accommodating single cells, the battery box body includes a bottom plate, and the bottom plate has a bottom surface facing away from the cavity; the cooling structure includes a cooling pipe, at least part of the cooling pipe is arranged on the bottom surface, the cooling pipe has a heat dissipation surface facing the bottom plate, and at least part of the heat dissipation surface is in contact with the bottom surface; wherein, the area of the region of the bottom surface with the orthographic projection of the single cell is the contact region, and the ratio of the area of the part of the heat dissipation surface in contact with the bottom surface to the area of the contact region is 30% - 50%.

[0006] It can be seen from the above technical scheme that the advantages and positive effects of the battery pack proposed by the utility model are as follows:

[0007] The battery pack proposed by the utility model includes a battery box body and a cooling structure; the battery box body includes a bottom plate; the cooling structure includes a cooling pipe, at least part of the cooling pipe is arranged on the bottom surface of the bottom plate, the cooling pipe has a heat dissipation surface facing the bottom plate, and at least part of the heat dissipation surface is in contact with the bottom surface; the ratio of the area of the part of the heat dissipation surface in contact with the bottom surface to the area of the region of the bottom surface with the orthographic projection of the single cell is 30% - 50%. Through the above structural design, the application can avoid the contact area between the cooling pipe and the bottom plate from being too small, thereby ensuring the temperature rise and fall efficiency between the cooling pipe and the bottom plate, and thus ensuring that the battery pack has a good heat dissipation effect. At the same time, the application can avoid the contact area between the cooling pipe and the bottom plate from being too large, thereby reducing the weight of the cooling structure and the material cost. Description of the Drawings

[0008] The various objects, features, and advantages of the present utility model will become more apparent by considering the following detailed description of the preferred embodiments of the present utility model in conjunction with the accompanying drawings. The accompanying drawings are only exemplary illustrations of the present utility model and are not necessarily drawn to scale. In the drawings, the same reference numerals always denote the same or similar components. Among them:

[0009] Figure 1 is a perspective structural view of a battery pack shown according to an exemplary embodiment;

[0010] Figure 2 is Figure 1 a perspective exploded view of;

[0011] Figure 3 is Figure 1 an enlarged view of part A in;

[0012] Figure 4 is Figure 2 a perspective structural view of the cooling structure shown;

[0013] Figure 5 is Figure 4 a bottom view of;

[0014] Figure 6 is Figure 5 an enlarged view of part B in;

[0015] Figure 7 is a cross-sectional view taken along Figure 6 the straight line E-E in;

[0016] Figure 8 is Figure 3 a side view of the liquid collection structure shown;

[0017] Figure 9 is Figure 8 a perspective cross-sectional view taken along the straight line G-G in.

[0018] The description of the reference numerals is as follows:

[0019] 100. Battery box body;

[0020] 110. Bottom plate;

[0021] 111. Bottom surface;

[0022] 200. Cooling structure;

[0023] 210. Cooling pipe;

[0024] 2101. Pipeline part;

[0025] 212. Straight pipe part;

[0026] 213. Elbow connection part;

[0027] 214. Inlet end;

[0028] 215. Outlet end;

[0029] 216. Liquid collecting connection part;

[0030] 220. Liquid collecting structure;

[0031] 221. Liquid inlet;

[0032] 222. Liquid outlet;

[0033] 223. First flow channel;

[0034] 224. Second flow channel;

[0035] 225. Fixing part;

[0036] 300. Single cell;

[0037] D1. Distance;

[0038] D2. Width;

[0039] D3. Width;

[0040] H. Height;

[0041] X. First direction;

[0042] Y. Second direction. Detailed implementation manners

[0043] Typical embodiments embodying the features and advantages of the present utility model will be described in detail in the following description. It should be understood that the present utility model can have various changes in different embodiments, all of which do not depart from the scope of the present utility model, and the descriptions and drawings therein are for illustrative purposes in essence and not for limiting the present utility model.

[0044] In the following description of different exemplary embodiments of the present utility model, reference is made to the accompanying drawings, which form a part of the present utility model, and in which different exemplary structures, systems and steps that can implement various aspects of the present utility model are shown by way of example. It should be understood that other specific solutions of components, structures, exemplary devices, systems and steps can be used, and structural and functional modifications can be made without departing from the scope of the present utility model. Moreover, although terms such as "above", "between", "inside" etc. may be used in this specification to describe different exemplary features and elements of the present utility model, these terms are used herein only for convenience, for example, according to the directions of the examples described in the accompanying drawings. Nothing in this specification should be construed as requiring a specific three-dimensional direction of the structure to fall within the scope of the present utility model.

[0045] Refer to Figure 1 , which representatively shows a schematic three-dimensional structure diagram of the battery pack proposed by the present utility model. In this exemplary embodiment, the battery pack proposed by the present utility model is described by taking an in-vehicle battery as an example. It is easy for those skilled in the art to understand that, in order to apply the relevant designs of the present utility model to other types of battery devices, various modifications, additions, substitutions, deletions, or other changes are made to the following specific embodiments, and these changes are still within the scope of the principle of the battery pack proposed by the present utility model.

[0046] As Figure 1 shown, in an embodiment of the present utility model, the battery pack proposed by the present utility model, wherein, includes a battery box body 100 and a cooling structure 200. Referring in conjunction with Figures 2 to 9 , Figure 2 representatively shows Figure 1 a schematic exploded three-dimensional view, wherein specifically the battery box body 100 and the cooling structure 200 are separated; Figure 3 representatively shows Figure 1 an enlarged schematic view of part A in Figure 4 representatively shows a schematic three-dimensional structure diagram of the cooling structure 200; Figure 5 representatively shows Figure 4 a bottom view of Figure 6 representatively shows Figure 5 an enlarged schematic view of part B in Figure 7 representatively shows a cross-sectional view taken along the straight line E-E in Figure 6 ; Figure 8 representatively shows a side view of the liquid collection structure 220; Figure 9 representatively shows Figure 8 a three-dimensional cross-sectional view taken along the straight line G-G in Figure 8 representatively shows a side view of the liquid collection structure 220; Figure 9 representatively shows Figure 8 a three-dimensional cross-sectional view taken along the straight line G-G in

[0047] As Figure 1 and Figure 2As shown, in an embodiment of the present utility model, the battery box body 100 has a cavity for accommodating the single cell 300, and the battery box body 100 includes a bottom plate 110, and the bottom plate 110 has a bottom surface 111 facing away from the cavity. The cooling structure 200 includes a cooling pipe 210, and at least a part of the cooling pipe 210 is disposed on the bottom surface 111 of the bottom plate 110. The cooling pipe 210 has a heat dissipation surface facing the bottom plate 110, and at least a part of the heat dissipation surface is in contact with the bottom surface 111 of the bottom plate 110, that is, the cooling structure 200 exchanges heat by contacting at least a part of the heat dissipation surface of the cooling structure 200 with the bottom surface 111 of the bottom plate 110. It should be noted that the so-called contact heat exchange can be understood as the direct contact between the heat dissipation film and the bottom surface 111, or it can be understood as the indirect contact between the two through other structures (such as a thermally conductive structural adhesive layer, etc.). On this basis, the area of the bottom surface 111 with the orthographic projection of the single cell 300 is the contact area, and the proportion of the area of the part of the heat dissipation surface in contact with the bottom surface 111 in the area of the contact area is 30% to 50%, such as 30%, 35%, 40%, 45%, 50%, etc. Through the above structural design, the present application can avoid too small contact area between the cooling pipe 210 and the bottom plate 110, thereby ensuring the temperature rise and fall efficiency between the cooling pipe 210 and the bottom plate 110, and thus ensuring good heat dissipation effect of the battery pack. At the same time, the present application can avoid too large contact area between the cooling pipe 210 and the bottom plate 110, thereby reducing the weight of the cooling structure 200 and reducing the material cost.

[0048] As Figure 4 and Figure 5 shown, in an embodiment of the present utility model, at least a part of the cooling pipe 210 can be arranged in a serpentine shape. Through the above structural design, the present utility model can optimize the arrangement form of the cooling pipe 210, which is beneficial to achieving a larger heat exchange area between the cooling pipe 210 and the bottom plate 110 and improving the cooling efficiency.

[0049] As Figure 6As shown, based on the structural design in which at least a part of the cooling pipe 210 is arranged in a serpentine shape. In an embodiment of the present utility model, the cooling pipe 210 arranged in a serpentine shape includes at least two straight pipe portions 212 and at least one elbow connecting portion 213. The at least two straight pipe portions 212 are arranged at intervals along a first direction X parallel to the bottom plate 110. The straight pipe portions 212 extend along a second direction Y parallel to the bottom plate 110 and perpendicular to the first direction X. Adjacent two straight pipe portions 212 are connected via the elbow connecting portion 213 between two ends on the same side in the second direction Y. On this basis, along the first direction X, the ratio of the distance D1 between adjacent two straight pipe portions 212 to the width D2 of the straight pipe portion 212 can be 0.35 - 0.65, such as 0.35, 0.4, 0.5, 0.6, 0.65, etc. Among them, when the width D2 of the straight pipe portion 212 is wider, if the distance D1 between adjacent two straight pipe portions 212 is closer, it will lead to a larger bending amplitude of the elbow connecting portion 213, which is not conducive to processing and arrangement, and at the same time will also cause the heat exchange area ratio between the cooling structure 200 and the bottom plate 110 to be too large. Furthermore, when the width D2 of the straight pipe portion 212 is narrower, if the distance D1 between adjacent two straight pipe portions 212 is farther, it will cause the heat exchange area ratio between the cooling structure 200 and the bottom plate 110 to be too small. Therefore, through the above structural design, the present utility model designs the ratio of the distance D1 between adjacent two straight pipe portions 212 to the width D2 of the straight pipe portion 212 to be within a suitable ratio range, which can meet the above design requirements for the heat exchange area ratio between the cooling structure 200 and the bottom plate 110. On this basis, it can also facilitate the processing and arrangement of the elbow connecting portion 213, be conducive to the serpentine arrangement of the cooling pipe 210, and improve the structural rationality and stability.

[0050] As Figure 5 As shown, based on the structural design in which at least a part of the cooling pipe 210 is arranged in a serpentine shape. In an embodiment of the present utility model, taking the plane where the bottom surface 111 of the bottom plate 110 is located as the reference plane, on this reference plane, the orthographic projection of each single cell 300 overlaps at least partially with the orthographic projections of at least two adjacent straight pipe portions 212. Through the above structural design, the present utility model can ensure the cooling efficiency of each single cell 300 via the bottom plate 110 and the cooling pipe 210.

[0051] Specifically, the orthographic projection of each single battery 300 overlaps with the orthographic projections of two adjacent straight pipe portions 212 partially. Through the above structural design, the present utility model comprehensively considers the size range of the battery, the width D2 of the straight pipe portion 212, and the distance D1 between two adjacent straight pipe portions 212, and adopts the design that the orthographic projection of each single battery 300 overlaps with the orthographic projections of two straight pipe portions 212 partially, which can facilitate the serpentine arrangement of the cooling pipe 210 while ensuring the cooling effect. In some embodiments, for a single single battery 300, the straight pipe portion 212 corresponding to its orthographic projection may also be one, three or more than three, and is not limited to this embodiment.

[0052] As Figure 5 shown, based on the structural design of the overlapping relationship between the orthographic projections of the single battery 300 and the straight pipe portion 212, in an embodiment of the present utility model, the orthographic projection of the single battery 300 can be equally divided into at least three parts arranged along the second direction Y by the orthographic projection of the straight pipe portion 212. For example, when the orthographic projection of each single battery 300 overlaps with the orthographic projections of two adjacent straight pipe portions 212 partially, the orthographic projection of the single battery 300 is equally divided into three parts arranged along the second direction Y by the orthographic projection of the straight pipe portion 212. Through the above structural design, the present utility model can make the cooling effect of the cooling pipe 210 on the single battery 300 more uniform.

[0053] As Figure 4 and Figure 5 shown, based on the structural design that at least a part of the cooling pipe 210 is arranged in a serpentine shape, in an embodiment of the present utility model, the cooling pipe 210 can include two pipeline parts 2101, and these two pipeline parts 2101 are arranged along a third direction parallel to the bottom plate 110. The two pipeline parts 2101 are in symmetrical shapes, and the symmetry axis extends along a fourth direction parallel to the bottom plate 110 and perpendicular to the third direction. Among them, in the embodiment shown in the drawings, the third direction is the first direction X, and the fourth direction is the second direction Y. Through the above structural design, the present utility model can make the cooling effect more balanced by using the two symmetrically distributed pipeline parts 2101 and avoid insufficient cooling in other parts.

[0054] As Figure 5 、 Figure 8 and Figure 9As shown, based on the structural design that the cooling pipe 210 includes two pipeline parts 2101, in an embodiment of the present utility model, each cooling pipe 210 of the pipeline parts 2101 can have two connection ends, which are respectively an inlet end 214 and an outlet end 215. The cooling structure 200 can also include a liquid collecting structure 220, and each connection end of the two pipeline parts 2101 is connected to the liquid collecting structure 220. Among them, the liquid collecting structure 220 has a first flow channel 223 and a second flow channel 224 inside. The two ends of the first flow channel 223 are respectively communicated with the two inlet ends 214 (that is, the inlet ends 214 of the two pipeline parts 2101 respectively), and the two ends of the second flow channel 224 are respectively communicated with the two outlet ends 215 (that is, the outlet ends 215 of the two pipeline parts 2101 respectively). On this basis, the liquid collecting structure 220 is connected with a liquid inlet 221 and a liquid outlet 222. The liquid inlet 221 is communicated with the first flow channel 223, and the liquid outlet 222 is communicated with the second flow channel 224. Through the above structural design, the present utility model can realize that the liquid inlet 221 and the liquid outlet 222 are simultaneously communicated with the cooling pipes 210 of the two pipeline parts 2101 via the flow channels of the liquid collecting structure 220, and accordingly can realize the flow equalization effect on the coolant flowing in the cooling pipes 210, and further improve the cooling effect.

[0055] Specifically, as Figure 5 shown, in an embodiment of the present utility model, the cooling pipe can include a liquid collecting connection part 216, and the liquid collecting connection part 216 is connected to the part of the cooling pipe arranged in a snake shape and has the above connection ends, such as two inlet ends 214 and two outlet ends 215.

[0056] As Figure 3 shown, based on the structural design of the liquid collecting structure, in an embodiment of the present utility model, a fixing part 225 can also be provided on the liquid collecting structure 220, and the fixing part 225 can be connected to the battery box body 100 via a connecting piece, such as the frame of the battery box body 100, and accordingly the connection and fixation of the liquid collecting structure 220 and the battery box body 100 are realized.

[0057] As Figure 7 shown, in an embodiment of the present utility model, the ratio of the height H to the width D3 of the cross section of the cooling pipe 210 can be 0.15 - 0.3, such as 0.15, 0.17, 0.2, 0.25, 0.3, etc. For example, for the straight pipe part 212 of the cooling pipe 210, the above width D3 is equivalent to the width D2 of the straight pipe part 212. Through the above structural design, the present utility model designs the ratio of the height H to the width D3 of the cross section of the cooling pipe 210 to be within a suitable range, which can ensure the contact area between the cooling pipe 210 and the bottom plate 110, and at the same time optimize the rationality of the cross-sectional shape of the cooling pipe 210 and ensure the flow performance of the coolant in the cooling pipe 210.

[0058] In an embodiment not illustrated in the present utility model, the battery pack proposed by the present utility model may further include a protective layer, which is disposed on the bottom surface 111 of the bottom plate 110, and the protective layer wraps the cooling pipe 210. For example, when the cooling pipe 210 is arranged in a serpentine shape, the protective layer can be disposed between adjacent pipeline structures and on the side of the pipeline structure facing away from the bottom plate 110, that is, the cross-section of the protective layer forms a continuous "mountain" shape, that is, the protective layer and the cooling pipe 210 are a profiling structure. Through the above structural design, the present utility model can provide a protection function for the cooling pipe 210 by using the protective layer, avoid the collision damage of the cooling pipe 210 exposed outside the bottom plate 110, and ensure the normal temperature reduction function of the battery pack. In addition, the present utility model can also use the protective layer to fill the gaps between the pipeline structures of the cooling pipe 210, thereby preventing the deformation of the pipeline structure and enabling the bottom of the battery pack to achieve an overall flat design.

[0059] Specifically, based on the design of the protective layer, in an embodiment of the present utility model, the protective layer can be a foam.

[0060] In an embodiment not illustrated in the present utility model, an anti-corrosion layer can be provided on the outer surface of the cooling pipe 210, such as, but not limited to, an anti-corrosion material layer provided by an electroplating process. Among them, since the coolant will flow in the cooling pipe 210, condensed water will be generated on the outer surface of the cooling pipe 210 due to different temperatures, and the condensed water will cause corrosion of the cooling pipe 210. Through the above structural design, the present utility model can improve the anti-corrosion performance of the cooling pipe 210 by using the anti-corrosion layer and extend the service life.

[0061] In an embodiment not illustrated in the present utility model, the thickness of the bottom plate 110 can be 0.5 mm to 1 mm, such as 0.5 mm, 0.6 mm, 0.7 mm, 0.9 mm, 1 mm, etc., and specifically can be preferably 0.8 mm. Further, the surface of the bottom plate 110 can be treated by an electrophoresis process to remove surface impurities. Through the above structural design, the present utility model can provide a better temperature reduction effect without affecting the strength of the battery box 100.

[0062] In an embodiment not illustrated in the present utility model, the material of the bottom plate 110 can be DC01 cold-rolled steel sheet. Through the above structural design, the present utility model can provide a better temperature reduction effect without affecting the strength of the battery box 100.

[0063] In an embodiment not illustrated in the present utility model, taking the surface of the bottom plate 110 being processed by electrophoresis process as an example, the surface roughness of the bottom plate 110 can be 1.5 - 3.2. Through the above structural design, since the bottom plate 110 will be in direct or indirect contact with the cooling pipe 210, the bottom plate 110 with a certain roughness can play a role in fixing and anti-sliding for the cooling pipe 210 to a certain extent, avoiding the cooling pipe 210 from moving on the bottom surface 111, and further ensuring the temperature reduction effect and structural stability of the battery pack.

[0064] It should be noted here that the battery packs shown in the drawings and described in this specification are only several examples of the many battery packs that can adopt the principle of the present utility model. It should be clearly understood that the principle of the present utility model is by no means limited to any details or any components of the battery packs shown in the drawings or described in this specification.

[0065] In summary, the battery pack proposed by the present utility model includes a battery box body 100 and a cooling structure 200; the battery box body 100 includes a bottom plate 110; the cooling structure 200 includes a cooling pipe 210, at least part of the cooling pipe 210 is arranged on the bottom surface 111 of the bottom plate 110, the cooling pipe 210 has a heat dissipation surface facing the bottom plate 110, and at least part of the heat dissipation surface is in contact with the bottom surface 111; the proportion of the area of the part of the heat dissipation surface in contact with the bottom surface 111 in the area of the region of the bottom surface 111 where the positive projection of the single battery 300 is located is 30% - 50%. Through the above structural design, the present application can avoid the contact area between the cooling pipe 210 and the bottom plate 110 from being too small, thereby ensuring the temperature rise and fall efficiency between the cooling pipe 210 and the bottom plate 110, and thus ensuring that the battery pack has a good heat dissipation effect. At the same time, the present application can avoid the contact area between the cooling pipe 210 and the bottom plate 110 from being too large, thereby reducing the weight of the cooling structure 200 and the material cost.

[0066] The exemplary embodiments of the battery pack proposed by the present utility model have been described and / or illustrated in detail above. However, the embodiments of the present utility model are not limited to the specific embodiments described herein. On the contrary, each component and / or step of each embodiment can be used independently and separately from the other components and / or steps described herein. Each component and / or each step of one embodiment can also be combined with the other components and / or steps of other embodiments. When introducing the elements / components / etc. described and / or illustrated herein, terms such as "a", "one" and "the above" etc. are used to indicate the existence of one or more elements / components / etc. The terms "comprising", "including" and "having" are used to mean an open inclusion and mean that there may be additional elements / components / etc. in addition to the listed elements / components / etc. In addition, the terms "first" and "second" etc. in the claims and the specification are only used as marks and are not numerical limitations on their objects.

[0067] Although the battery pack proposed by the present utility model has been described according to different specific embodiments, those skilled in the art will recognize that changes can be made to the implementation of the present utility model within the spirit and scope of the claims.

Claims

1. A battery pack, characterized in that: include: A battery box having a cavity for accommodating a single battery, the battery box comprising a bottom plate, the bottom plate having a bottom surface facing away from the cavity; as well as A cooling structure, comprising a cooling pipe, wherein the cooling pipe is at least partially disposed on the bottom surface, the cooling pipe has a heat dissipation surface facing the bottom plate, and the heat dissipation surface is at least partially in contact with the bottom surface; The area of ​​the bottom surface having the orthographic projection of the single battery is the contact area, and the area of ​​the portion of the heat dissipation surface in contact with the bottom surface accounts for 30% to 50% of the area of ​​the contact area.

2. The battery pack according to claim 1, characterized in that: At least a portion of the cooling pipe is arranged in a serpentine shape.

3. The battery pack according to claim 2, characterized in that: The cooling pipe arranged in a serpentine shape includes at least two straight pipe portions and at least one bent pipe connection portion, at least two of the straight pipe portions are arranged at intervals along a first direction parallel to the base plate, the straight pipe portions extend along a second direction parallel to the base plate and perpendicular to the first direction, and the two ends of two adjacent straight pipe portions located on the same side in the second direction are connected via the bent pipe connection portion; wherein, along the first direction, the ratio of the distance between two adjacent straight pipe portions to the width of the straight pipe portion is 0.35 to 0.

65.

4. The battery pack according to claim 3, characterized in that: The plane where the bottom surface is located is taken as a reference plane, on which the orthographic projection of each of the single cells partially overlaps with the orthographic projections of at least two adjacent straight tube portions.

5. The battery pack according to claim 4, characterized in that: On the reference plane, the orthographic projection of the single battery is equally divided into at least three parts arranged along the second direction by the orthographic projection of the straight tube portion.

6. The battery pack according to claim 2, characterized in that: The cooling pipe includes two pipe parts, which are arranged along a third direction parallel to the base plate. The two pipe parts are symmetrical in shape, and the axis of symmetry extends along a fourth direction parallel to the base plate and perpendicular to the third direction.

7. The battery pack according to claim 6, characterized in that: The cooling pipe of each of the pipeline parts has two connecting ends, which are an inlet end and an outlet end respectively; wherein the cooling structure also includes a liquid collecting structure, and each of the connecting ends of the two pipeline parts is connected to the liquid collecting structure, and the liquid collecting structure has a first flow channel and a second flow channel inside, and the two ends of the first flow channel are respectively connected to the two inlet ends, and the two ends of the second flow channel are respectively connected to the two outlet ends; wherein the liquid collecting structure is connected with a liquid inlet and a liquid outlet, and the liquid inlet is connected to the first flow channel, and the liquid outlet is connected to the second flow channel.

8. The battery pack according to claim 1, characterized in that: The ratio of the height to the width of the cross section of the cooling pipe is 0.15 to 0.

3.

9. The battery pack according to claim 1, characterized in that: The battery pack further includes a protective layer, which is disposed on the bottom surface and wraps the cooling tube.

10. The battery pack according to claim 1, characterized in that: The outer surface of the cooling pipe is provided with an anti-corrosion layer; and / or The thickness of the bottom plate is 0.5 mm to 1 mm; and / or The base plate is made of DC01 cold-rolled steel plate; and / or The surface roughness of the bottom plate is 1.5-3.2.

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