Self-flanging top cover of pole

Abstract

The utility model discloses a pole self-flanging top cover, which comprises a top cover sheet and a pole, the top cover sheet is provided with a step hole, the step hole comprises a first hole section, a second hole section and a third hole section which are sequentially communicated along the vertical direction, and the cross sectional area of the first hole section, the cross sectional area of the second hole section and the cross sectional area of the third hole section are sequentially reduced; the pole comprises a first pole section, a second pole section, a first protruding part and a second protruding part, the cross sectional area of the first pole section is larger than that of the second pole section, the first protruding part surrounds the peripheral surface of the upper end of the first pole section by a circle, the second protruding part surrounds the peripheral surface of the lower end of the second pole section by a circle, the first protruding part is arranged in the first hole section, and the second protruding part is arranged in the second hole section. The first column section is arranged in the second hole section, the second column section is arranged in the third hole section, and the second protruding part extends out of the third hole section. The pole self-flanging top cover disclosed by the embodiment of the utility model has the advantages of increasing the internal space of the battery and improving the utilization rate of the battery core in the battery.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a pole self-flanging top cover. Background Art

[0002] With the development of new energy industry, the demand for new energy power batteries is increasing. New energy power batteries are mainly composed of shell, battery cell and top cover. The top cover is composed of pole riveted or injection molded. The pole is the part that conducts the inside and outside of the power battery. One end of the pole is connected to the external circuit of the power battery, and the other end of the pole is connected to the battery cell inside the power battery to realize the charging and discharging function of the battery.

[0003] In the related art, the poles of the power battery extend out of the top cover plate to a high height, which reduces the space inside the battery, resulting in a lower utilization rate of the battery cells inside the battery, and does not meet the high-capacity battery requirements of the market demand. Utility Model Content

[0004] The utility model aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiment of the utility model provides a pole self-flanging top cover, which has the advantages of increasing the space inside the battery and improving the utilization rate of the battery cells inside the battery.

[0005] The pole self-flanging top cover of the utility model embodiment comprises:

[0006] A top cover sheet, wherein the top cover sheet has a stepped hole, wherein the stepped hole comprises a first hole segment, a second hole segment, and a third hole segment which are sequentially connected from the upper surface of the top cover sheet toward the lower surface of the top cover sheet in the up-down direction, wherein the cross-sectional areas of the first hole segment, the second hole segment, and the third hole segment decrease sequentially;

[0007] A pole, the pole comprising a first pole segment, a second pole segment, a first protrusion and a second protrusion, the first pole segment being connected to the second pole segment, the cross-sectional area of ​​the first pole segment being larger than the cross-sectional area of ​​the second pole segment, the first protrusion being arranged around the outer circumference of the upper end of the first pole segment, the second protrusion being arranged around the outer circumference of the lower end of the second pole segment, the first protrusion being arranged in the first hole segment, the first pole segment being arranged in the second hole segment, the second pole segment being arranged in the third hole segment, and the second protrusion extending out of the third hole segment.

[0008] The pole of the embodiment of the utility model has a self-flange top cover, and the step hole is arranged into a plurality of hole segments with successively decreasing cross-sectional areas, and the plurality of hole segments extend from the upper surface of the top cover sheet to the lower surface of the top cover sheet, thereby reducing the length of the end of the pole extending out of the upper surface of the top cover sheet, increasing the space inside the battery, improving the utilization rate of the battery cells inside the battery, and increasing the energy density of the battery cells. The pole is arranged into a plurality of column segments that correspond one-to-one to the plurality of hole segments, so that the pole is firmly installed in the step hole, and the degree of fit between the pole and the step hole is improved.

[0009] In some embodiments, the upper end of the second hole segment is connected to the lower end of the first hole segment, the lower end of the second hole segment extends toward the lower surface of the top cover sheet and protrudes from the lower surface of the top cover sheet, and the size of the second hole segment in the up and down direction is larger than the size of the first hole segment in the up and down direction.

[0010] In some embodiments, the size of the first protrusion in the up-down direction is smaller than the size of the first column segment in the up-down direction, and the size of the second protrusion in the up-down direction is smaller than the size of the second column segment in the up-down direction.

[0011] In some embodiments, the pole self-flanged top cover further comprises:

[0012] A first plastic part, the first plastic part is arranged around at least a portion of the outer circumference of the pole, one end of the first plastic part extends to the top of the first protrusion, and the other end of the first plastic part extends to the lower end of the first column section;

[0013] A second plastic part, wherein the second plastic part is arranged on the lower surface of the top cover sheet, one end of the second plastic part is located between the lower surface of the top cover sheet and the second protrusion and is arranged around the outer circumference of the second column segment, and the other end of the second plastic part extends along the lower surface of the top cover sheet in a direction away from the step hole.

[0014] In some embodiments, the upper end of the first column segment protrudes from the upper surface of the top cover sheet, and one end of the first plastic part protrudes from the upper surface of the top cover sheet and is flush with the top surface of the first protruding portion.

[0015] In some embodiments, the pole self-flange top cover also includes a seal, which is arranged around at least part of the outer circumference of the pole, one end of the seal extends to the lower end of the first column segment, and the other end of the seal extends to the lower end of the second column segment, and the seal is located between the first plastic part and the second plastic part.

[0016] In some embodiments, the pole self-flange top cover also includes a connector, which is disposed on the lower surface of the second plastic part, at least a portion of one end of the connector is connected to the second protrusion, and the other end of the connector extends in a direction away from the second protrusion.

[0017] In some embodiments, at least a portion of one end of the connector extends to a lower surface of the second column segment.

[0018] In some embodiments, the pole self-flanged top cover further includes a limiting member, the limiting member is disposed on the lower surface of the top cover sheet, and the limiting member is used to limit the connecting member.

[0019] In some embodiments, the step hole also includes a fourth hole segment, the first hole segment, the second hole segment, the fourth hole segment and the third hole segment are connected in sequence, the pole also includes a third column segment, the first column segment, the third column segment and the second column segment are connected in sequence, the cross-sectional area of ​​the third column segment is smaller than the cross-sectional area of ​​the first column segment and larger than the cross-sectional area of ​​the second column segment, and the third column segment is arranged in the fourth hole segment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the outer side of the pole self-flanged top cover of the embodiment of the utility model.

[0021] Figure 2 It is a cross-sectional view of a pole self-flanged top cover according to an embodiment of the utility model.

[0022] Figure 3 yes Figure 2 Enlarged schematic diagram of part A.

[0023] Figure 4 It is a schematic diagram of the inner side of the pole self-flanged top cover of the embodiment of the utility model.

[0024] Figure numerals: 1, top cover plate; 11, step hole; 111, first hole section; 112, second hole section; 113, third hole section; 12, explosion-proof valve; 2, pole; 21, first column section; 22, second column section; 23, first protrusion; 24, second protrusion; 31, first plastic part; 32, second plastic part; 33, sealing part; 4, connecting part; 41, first connecting piece; 42, transition section; 43, second connecting piece; 5, limit part. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention.

[0026] like Figure 1-4 As shown, the pole self-flanged top cover of the embodiment of the utility model comprises a top cover sheet 1 and a pole 2. The top cover sheet 1 has a step hole 11, and the step hole 11 comprises a first hole section 111, a second hole section 112 and a third hole section 113 which are sequentially connected from the upper surface of the top cover sheet 1 toward the lower surface of the top cover sheet 1 in the up-down direction, and the cross-sectional area of ​​the first hole section 111, the cross-sectional area of ​​the second hole section 112 and the cross-sectional area of ​​the third hole section 113 decrease in sequence. Preferably, the cross-sectional area of ​​the first hole section 111, the cross-sectional area of ​​the second hole section 112 and the cross-sectional area of ​​the third hole section 113 are all circular. The central axis of the first hole section 111, the central axis of the second hole section 112 and the central axis of the third hole section 113 are collinear.

[0027] The pole 2 includes a first column segment 21, a second column segment 22, a first protrusion 23 and a second protrusion 24. The first column segment 21 is connected to the second column segment 22. The cross-sectional area of ​​the first column segment 21 is greater than the cross-sectional area of ​​the second column segment 22. The first protrusion 23 is arranged around the outer circumference of the upper end of the first column segment 21, and the second protrusion 24 is arranged around the outer circumference of the lower end of the second column segment 22. The first protrusion 23 is arranged in the first hole segment 111, the first column segment 21 is arranged in the second hole segment 112, the second column segment 22 is arranged in the third hole segment 113, and the second protrusion 24 extends out of the third hole segment 113.

[0028] Specifically, the lower end of the first column section 21 is disposed in the second hole section 112, the upper end of the first column section 21 is located in the first hole section 111 and protrudes from the upper surface of the top cover sheet 1, and the outer circumference of the first protrusion 23 is adapted to the inner circumference of the first hole section 111. The cross-section of the first column section 21 and the cross-section of the second column section 22 are both circular, the lower end of the first column section 21 is connected to the upper end of the second column section 22, and the central axis of the first column section 21 is collinear with the central axis of the second column section 22.

[0029] The pole of the embodiment of the utility model has a self-flange top cover, and the step hole 11 is arranged into a plurality of hole segments with successively decreasing cross-sectional areas, and the plurality of hole segments extend from the upper surface of the top cover sheet 1 to the lower surface of the top cover sheet 1, thereby reducing the length of the end of the pole 2 extending out of the upper surface of the top cover sheet 1, increasing the space inside the battery, improving the utilization rate of the battery cells inside the battery, and increasing the energy density of the battery cells. The pole 2 is arranged into a plurality of column segments that correspond one-to-one to the plurality of hole segments, so that the pole 2 is firmly installed in the step hole 11, and the degree of fit between the pole 2 and the step hole 11 is improved.

[0030] Specifically, one end of the first protrusion 23 is arranged around the outer circumference of the upper end of the first column section 21, and the other end of the first protrusion 23 can move between a first position and a second position. When the other end of the first protrusion 23 is located at the first position, the other end of the first protrusion 23 extends in the up-down direction in a direction away from the first column section 21. When the other end of the first protrusion 23 is located at the second position, the other end of the first protrusion 23 extends in a horizontal direction, and the horizontal direction is orthogonal to the up-down direction.

[0031] One end of the second protrusion 24 is arranged around the outer circumference of the lower end of the second column section 22, and the other end of the second protrusion 24 can move between the third position and the fourth position. When the other end of the second protrusion 24 is located at the third position, the other end of the second protrusion 24 extends in the up-down direction in a direction away from the second column section 22. When the other end of the second protrusion 24 is located at the fourth position, the other end of the second protrusion 24 extends in the horizontal direction.

[0032] When the pole 2 is installed in the stepped hole 11 , the first protrusion 23 can automatically move from the first position to the second position and fit in the first pole section 21 , and the second protrusion 24 automatically moves from the third position to the fourth position after extending out of the third hole section 113 .

[0033] In some embodiments, the step hole 11 is not limited to only including the first hole segment 111, the second hole segment 112 and the third hole segment 113, and also includes a fourth hole segment (not shown), the first hole segment 111, the second hole segment 112, the fourth hole segment and the third hole segment 113 are connected in sequence, and the cross-sectional areas of the first hole segment 111, the second hole segment 112, the fourth hole segment and the third hole segment 113 are reduced in sequence. The pole 2 is not limited to only including the first column segment 21, the second column segment 22, the first protrusion 23 and the second protrusion 24, and the pole 2 also includes a third column segment (not shown), the first column segment 21, the third column segment and the second column segment 22 are connected in sequence, the cross-sectional area of ​​the third column segment is smaller than the cross-sectional area of ​​the first column segment 21 and larger than the cross-sectional area of ​​the second column segment 22, and the third column segment is arranged in the fourth hole segment.

[0034] In some embodiments, an explosion-proof valve 12 is also provided on the top cover sheet 1, and there are two step holes 11. The explosion-proof valve 12 is arranged between the two step holes 11 and is spaced apart from the step holes 11. One of the step holes 11 is used to install the positive electrode column, and the other step hole 11 is used to install the negative electrode column.

[0035] In some embodiments, the upper end of the second hole segment 112 is connected to the lower end of the first hole segment 111, the lower end of the second hole segment 112 extends toward the lower surface of the top cover sheet 1 and protrudes from the lower surface of the top cover sheet 1, and the size of the second hole segment 112 in the up and down direction is greater than the size of the first hole segment 111 in the up and down direction.

[0036] Specifically, through the above-mentioned arrangement, the length of the lower end of the step hole 11 extending on the lower surface of the top cover sheet 1 is extended, and the length of the upper end of the step hole 11 extending out of the upper surface of the top cover sheet 1 is reduced, so that the size of the upper end of the pole 2 extending out of the upper surface of the top cover sheet 1 is reduced, which effectively increases the space inside the battery and improves the utilization rate of the battery cells inside the battery.

[0037] In some embodiments, the size of the first protrusion 23 in the vertical direction is smaller than the size of the first column section 21 in the vertical direction, specifically, the size of the first protrusion 23 in the vertical direction is greater than or equal to 0.6 mm. The size of the second protrusion 24 in the vertical direction is smaller than the size of the second column section 22 in the vertical direction, specifically, the size of the second protrusion 24 in the vertical direction is greater than or equal to 0.6 mm, which ensures the support strength of the first protrusion 23 and the second protrusion 24, and improves the firmness of the pole 2 installed in the step hole 11.

[0038] In some embodiments, the pole self-flange top cover further includes a first plastic part 31 and a second plastic part 32. The first plastic part 31 is arranged around at least part of the outer circumference of the pole 2. One end of the first plastic part 31 (such as Figure 3 The upper end of the first plastic part 31 shown in FIG. 1 ) extends to the top of the first protrusion 23, and the other end of the first plastic part 31 (as shown in FIG. Figure 3 The first plastic part 31 shown in FIG. 1 extends to the lower end of the first column segment 21. Specifically, the first plastic part 31 is located between the outer circumference of the pole 2 and the inner circumference of the step hole 11, the upper end of the first plastic part 31 extends to the first hole segment 111 and extends out of the upper end of the first hole segment 111, the upper end of the first plastic part 31 is flush with the top surface of the first protrusion 23, and the lower end of the first plastic part 31 extends to the lower end of the second hole segment 112 to protect the pole 2.

[0039] The second plastic part 32 is disposed on the lower surface of the top cover sheet 1, and one end of the second plastic part 32 (such as Figure 3 The lower end of the second plastic part 32 shown in FIG. 1 is located between the lower surface of the top cover sheet 1 and the second protrusion 24 and is arranged around the outer circumference of the second column section 22. The other end of the second plastic part 32 (as shown in FIG. 1 ) is located between the lower surface of the top cover sheet 1 and the second protrusion 24 and is arranged around the outer circumference of the second column section 22. Figure 3 The upper end of the second plastic part 32 shown in the figure extends along the lower surface of the top cover sheet 1 in a direction away from the step hole 11. Specifically, the lower end of the second plastic part 32 contacts the outer circumference of the lower end of the second column segment 22, and the upper end of the second plastic part 32 extends along the lower surface of the top cover sheet 1, the outer circumference of the third hole segment 113, and the outer circumference of the second hole segment 112 in a direction away from the step hole 11.

[0040] In some embodiments, the pole self-flange top cover further includes a seal 33, which is arranged around at least part of the outer circumference of the pole 2. One end of the seal 33 (such as Figure 3The upper end of the seal 33 shown in FIG. 1 ) extends to the lower end of the first column section 21, and the other end of the seal 33 (as shown in FIG. Figure 3 The lower end of the sealing member 33 shown in the figure extends to the lower end of the second column section 22 , and the sealing member 33 is located between the first plastic member 31 and the second plastic member 32 .

[0041] Specifically, the seal 33 extends around the outer peripheral contour of the second column section 22, and the seal 33 is squeezed between the pole 2 and the step hole 11, playing a sealing role to ensure the sealing of the entire battery.

[0042] In some embodiments, the first plastic part 31 , the second plastic part 32 and the sealing part 33 are first arranged on the outer circumference of the pole 2 , and then the pole 2 is installed in the step hole 11 , which can effectively improve assembly efficiency and reduce material costs.

[0043] In some embodiments, the pole self-flange top cover also includes a connector 4, which is disposed on the lower surface of the second plastic part 32, at least a portion of one end of the connector 4 is connected to the second protrusion 24, and the other end of the connector 4 extends in a direction away from the second protrusion 24.

[0044] Specifically, the connector 4 is used to connect the pole 2 and the battery cell inside the battery. The connector 4 includes a first connecting piece 41, a transition section 42 and a second connecting piece 43. The transition section 42 connects one end of the first connecting piece 41 and one end of the second connecting piece 43. The other end of the first connecting piece 41 and the other end of the second connecting piece 43 extend in a direction away from the transition section 42.

[0045] In some embodiments, one side of the transition section 42 is arc-shaped and matches the arc shape of the outer peripheral surface of the second protruding portion 24 to improve the connectivity between the transition section 42 and the second protruding portion 24 .

[0046] In some embodiments, at least a portion of one end of the transition section 42 extends to the lower surface of the second column section 22 to facilitate welding of the transition section 42 and the second column section 22 .

[0047] In some embodiments, the dimension of the connecting member 4 in the up-down direction is greater than or equal to 0.5 mm, thereby ensuring the structural strength of the connecting member 4 .

[0048] In some embodiments, the pole self-flanged top cover further includes a limiting member 5 , which is disposed on the lower surface of the top cover sheet 1 , and is used to limit the connector 4 .

[0049] Specifically, there are multiple limit members 5, which are arranged at intervals around the outer circumference of the first connecting piece 41 and the second connecting piece 43 to position the connecting piece 4. The setting of the limit members 5 can also increase the strength of the second plastic part 32, improve the deformation resistance of the second plastic part 32, and the limit members 5 can also improve the torsion resistance of the pole 2.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0052] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0054] In the present utility model, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are illustrative and cannot be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A pole self-flange top cover, characterized in that: include: A top cover sheet (1), the top cover sheet (1) having a stepped hole (11), the stepped hole (11) comprising a first hole section (111), a second hole section (112) and a third hole section (113) which are connected in sequence from the upper surface of the top cover sheet (1) toward the lower surface of the top cover sheet (1) in an up-down direction, the cross-sectional area of ​​the first hole section (111), the cross-sectional area of ​​the second hole section (112) and the cross-sectional area of ​​the third hole section (113) decreasing in sequence; A pole (2), the pole (2) comprising a first pole section (21), a second pole section (22), a first protruding portion (23) and a second protruding portion (24), the first pole section (21) being connected to the second pole section (22), the cross-sectional area of ​​the first pole section (21) being larger than the cross-sectional area of ​​the second pole section (22), the first protruding portion (23) being arranged around the outer circumference of the upper end of the first pole section (21), the second protruding portion (24) being arranged around the outer circumference of the lower end of the second pole section (22), the first protruding portion (23) being arranged in the first hole section (111), the first pole section (21) being arranged in the second hole section (112), the second pole section (22) being arranged in the third hole section (113), and the second protruding portion (24) extending out of the third hole section (113).

2. The pole self-flanging top cover according to claim 1, characterized in that: The upper end of the second hole segment (112) is connected to the lower end of the first hole segment (111), the lower end of the second hole segment (112) extends toward the lower surface of the top cover sheet (1) and protrudes from the lower surface of the top cover sheet (1), and the size of the second hole segment (112) in the up-down direction is greater than the size of the first hole segment (111) in the up-down direction.

3. The pole self-flanging top cover according to claim 1, characterized in that: The size of the first protrusion (23) in the up-down direction is smaller than the size of the first column section (21) in the up-down direction, and the size of the second protrusion (24) in the up-down direction is smaller than the size of the second column section (22) in the up-down direction.

4. The pole self-flanging top cover according to claim 1, characterized in that: Also includes: A first plastic part (31), the first plastic part (31) being arranged around at least part of the outer circumference of the pole (2), one end of the first plastic part (31) extending to the top of the first protruding portion (23), and the other end of the first plastic part (31) extending to the lower end of the first pole section (21); A second plastic part (32), the second plastic part (32) is arranged on the lower surface of the top cover sheet (1), one end of the second plastic part (32) is located between the lower surface of the top cover sheet (1) and the second protruding portion (24) and is arranged around the outer circumference of the second column section (22), and the other end of the second plastic part (32) extends along the lower surface of the top cover sheet (1) in a direction away from the step hole (11).

5. The pole self-flanging top cover according to claim 4, characterized in that: The upper end of the first column section (21) protrudes from the upper surface of the top cover sheet (1), and one end of the first plastic part (31) protrudes from the upper surface of the top cover sheet (1) and is flush with the top surface of the first protruding portion (23).

6. The pole self-flanging top cover according to claim 4, characterized in that: It also includes a sealing member (33), which is arranged around at least part of the outer circumference of the pole (2), one end of the sealing member (33) extends to the lower end of the first column section (21), and the other end of the sealing member (33) extends to the lower end of the second column section (22), and the sealing member (33) is located between the first plastic member (31) and the second plastic member (32).

7. The pole self-flanging top cover according to claim 4, characterized in that: It also comprises a connecting piece (4), wherein the connecting piece (4) is arranged on the lower surface of the second plastic part (32), at least a part of one end of the connecting piece (4) is connected to the second protruding portion (24), and the other end of the connecting piece (4) extends in a direction away from the second protruding portion (24).

8. The pole self-flanging top cover according to claim 7, characterized in that: At least a portion of one end of the connecting member (4) extends to the lower surface of the second column section (22).

9. The pole self-flanging top cover according to claim 7, characterized in that: It also comprises a limiting member (5), wherein the limiting member (5) is arranged on the lower surface of the top cover sheet (1), and the limiting member (5) is used to limit the position of the connecting member (4).

10. The pole self-flanging top cover according to any one of claims 1 to 9, characterized in that: The step hole (11) further comprises a fourth hole section, the first hole section (111), the second hole section (112), the fourth hole section and the third hole section (113) are connected in sequence, the pole (2) further comprises a third column section, the first column section (21), the third column section and the second column section (22) are connected in sequence, the cross-sectional area of ​​the third column section is smaller than the cross-sectional area of ​​the first column section (21) and larger than the cross-sectional area of ​​the second column section (22), and the third column section is arranged in the fourth hole section.

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