Main shaft of photovoltaic tracking support and photovoltaic tracking support

Abstract

The utility model discloses a main shaft of a photovoltaic tracking support and the photovoltaic tracking support. The cross section of the main shaft is a compact cross section. The cross section of the main shaft comprises four plane sections and four arc sections, and the four plane sections and the four arc sections are sequentially and alternately arranged in the circumferential direction to form a square tubular structure; the widths of the four plane sections are equal, and the radians of the four arc sections are also equal, so that a square tubular structure formed by the four plane sections and the four arc sections is a centrosymmetric graph relative to the axis of the main shaft. The ratio of the width x'of the plane section to the wall thickness t of the main shaft, namely the width-to-thickness ratio x ' / t is between 20 and 25, and the torsion strength and the bending strength can be balanced and considered, so that better stability is achieved.

Description

Technical Field

[0001] This utility model belongs to the field of photovoltaic technology, and in particular to a main shaft and a photovoltaic tracking bracket. Background Technology

[0002] For photovoltaic (PV) tracking brackets, the spindle transmits torque, enabling the bracket to rotate the PV modules according to the controller's instructions. Simultaneously, it also transmits the PV modules themselves and the loads they bear, such as wind and snow, back to the support column. Currently, there are various types of spindles for PV tracking brackets on the market. Among common spindle types, square-tube shaped spindles have good bending strength but poor torsional strength. To address this issue of poor torsional strength...

[0003] Existing technology provides a main shaft comprising four planar segments and four circular arc segments, with the planar and circular arc segments alternating sequentially. However, when simply changing the cross-sectional shape of the main shaft from a rectangle (or square) to alternating planar and circular arc segments, the existing technology only considers the bending strength of the main shaft while neglecting its torsional strength. It fails to find a good balance between torsional and bending strength, leading to warping and deformation of the main shaft. This severely affects the normal operation of the photovoltaic tracking bracket, resulting in a situation where one aspect is prioritized at the expense of the other. Utility Model Content

[0004] The purpose of this invention is to provide a main shaft and a photovoltaic tracking bracket that have both superior torsional strength and bending strength, and better overall structural strength.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: a main shaft for a photovoltaic tracking bracket, wherein the cross-section of the main shaft is a compact cross-section, the cross-section of the main shaft includes four planar segments and four circular arc segments, the four planar segments and the four circular arc segments are arranged alternately along the circumference to form a square tubular structure; the widths of the four planar segments are all equal and the curvatures of the four circular arc segments are also equal, so that the square tubular structure formed by the four planar segments and the four circular arc segments is a centrally symmetrical figure with respect to the axis of the main shaft, and the ratio of the width x' of the planar segment to the wall thickness t of the main shaft, i.e., the width-to-thickness ratio x' / t, is between 20 and 25.

[0006] As a further improvement of the present invention, the width-to-thickness ratio x' / t is between 20 and 22.5.

[0007] As a further improvement of the present invention, the spindle is made of Q355 steel, Q420 steel, Q500 steel or Q550 steel.

[0008] As a further improvement of this utility model, the radius of curvature of the arc segment is 25mm to 70mm.

[0009] As a further improvement of this utility model, the wall thickness t of the spindle is 2mm to 3mm.

[0010] As a further improvement of the present invention, the original width x of the spindle is the vertical distance between the outer walls of the two opposite planar segments, the radius of curvature of the arc segment is r, where x' = x - 2r, and the original width x of the spindle is 100mm to 200mm.

[0011] As a further improvement of the present invention, the main shaft includes multiple shaft segments that are separately arranged, and the multiple shaft segments are connected end to end to form a whole.

[0012] As a further improvement of the present invention, the main shaft includes a first shaft segment, a second shaft segment, and a connector. The first shaft segment and the second shaft segment are connected end to end. The first shaft segment includes a first end and a second end arranged in opposite directions. The second shaft segment includes a third end and a fourth end arranged in opposite directions. The second end and the third end are arranged close to each other in the straight direction in which the main shaft extends. The connector covers the outside of the second end and the third end.

[0013] As a further improvement of this utility model, the connector is either a separate type or an integral type.

[0014] As a further improvement of the present invention, the spindle further includes a fastener, the connector covers the outside of the second end and the third end, and the fastener passes through the connector, the second end and the third end.

[0015] As a further improvement of the present invention, the main shaft includes a first shaft segment, a second shaft segment, and a fastener. The first shaft segment and the second shaft segment each include a constricted end and a non-constricted receiving end arranged oppositely. The constricted end of the first shaft segment is inserted into the receiving end of the second shaft segment, and the fastener passes through the constricted end of the first shaft segment and the receiving end of the second shaft segment.

[0016] To achieve the above objectives, this utility model also provides a photovoltaic tracking bracket, including a column, a driving device, and purlins, and further including the main shaft of the photovoltaic tracking bracket as described above. The main shaft of the photovoltaic tracking bracket is installed on the top of the column, and the purlins are installed on the main shaft of the photovoltaic tracking bracket to support the photovoltaic modules. The driving end of the driving device is connected to the main shaft of the photovoltaic tracking bracket to drive the main shaft of the photovoltaic tracking bracket to rotate.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] The main shaft of this photovoltaic tracking bracket has a compact cross-section, comprising four planar segments and four circular arc segments. These four planar segments and four circular arc segments are alternately arranged circumferentially to form a rectangular tubular structure. By setting the ratio of the width of the planar segments to the wall thickness of the main shaft (width-to-thickness ratio) between 20 and 25, the main shaft of this photovoltaic tracking bracket possesses both superior bending and torsional strength, achieving a balance between the two, thus resulting in better stability. Attached Figure Description

[0019] Figure 1 This is a perspective view of the main shaft embodiment of the photovoltaic tracking bracket of this utility model;

[0020] Figure 2 yes Figure 1 Enlarged view of section A;

[0021] Figure 3 yes Figure 1 The main view;

[0022] Figure 4 yes Figure 3 Enlarged view of section B;

[0023] Figure 5 This is a three-dimensional assembly diagram of the main shaft of the photovoltaic tracking bracket of this utility model, in embodiment two.

[0024] Figure 6 yes Figure 5 3D exploded view;

[0025] Figure 7 yes Figure 5 Enlarged view of section C;

[0026] Figure 8 This is a three-dimensional assembly diagram of the connector and fastener in Embodiment 2 of this utility model;

[0027] Figure 9 yes Figure 8 Top view;

[0028] Figure 10 It is along Figure 9 A cross-sectional view of the EE line;

[0029] Figure 11 This is a three-dimensional assembly schematic diagram of the main shaft of the photovoltaic tracking bracket of this utility model, embodiment three;

[0030] Figure 12 yes Figure 11 Enlarged view of section G in the middle;

[0031] Figure 13 This is a three-dimensional assembly diagram of photovoltaic modules installed on the photovoltaic tracking bracket of this utility model;

[0032] Figure 14 This is a three-dimensional assembly diagram of the photovoltaic tracking bracket of this utility model after removing the photovoltaic modules;

[0033] Figure 15 yes Figure 14 Enlarged view of section H in the middle. Detailed Implementation

[0034] The exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. If several embodiments exist, features in these embodiments may be combined with each other without conflict. When the description refers to the drawings, unless otherwise stated, the same numbers in different drawings represent the same or similar elements. The descriptions in the following exemplary embodiments do not represent all embodiments consistent with the present invention; rather, they are merely examples of apparatuses, products, and / or methods consistent with some aspects of the present invention as set forth in the claims.

[0035] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the scope of protection of this invention. The singular forms “a,” “the,” or “the” used in the specification and claims of this invention are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0036] It should be understood that the terms "first," "second," and similar words used in the specification and claims of this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish the features. Similarly, the terms "an" or "a" do not indicate a quantity limitation, but rather indicate the presence of at least one. Unless otherwise stated, the terms "front," "back," "left," "right," "upper," "lower," and similar words appearing in this utility model are for ease of explanation only and are not limited to a specific location or spatial orientation. The terms "comprising" or "including" are an open-ended expression, meaning that the element preceding "comprising" or "including" covers the element following "comprising" or "including" and its equivalents, which does not exclude that the element preceding "comprising" or "including" may also include other elements. If "several" appears in this utility model, it means two or more.

[0037] Please refer to Figures 1 to 15 Especially Figure 14 and Figure 15As shown, this utility model discloses a photovoltaic tracking bracket 100, including a main shaft 1, a column 2, a drive device 3, and purlins 4. The main shaft 1 of the photovoltaic tracking bracket 100 is mounted on the top of the column 2, and the purlins 4 are mounted on the main shaft 1 of the photovoltaic tracking bracket 100 for support. Figure 13 The photovoltaic module 200 shown has a drive device 3 whose drive end is connected to the main shaft 1 of the photovoltaic tracking bracket 100 to drive the main shaft 1 of the photovoltaic tracking bracket 100 to rotate, thereby driving the purlins 4 and the purlins mounted on the main shaft 1 of the photovoltaic tracking bracket 100 to rotate. Figure 13 The photovoltaic module 200 shown rotates to follow the movement of the sun in order to generate more electricity.

[0038] Please refer to Figures 1 to 12 and Figure 15 The diagram shows the main shaft 1 of the photovoltaic tracking bracket 100 of this invention. The cross-section of the main shaft 1 is a compact cross-section (the concept of a compact cross-section is well-known in the art and will not be elaborated further). The main shaft 1 of the photovoltaic tracking bracket 100 includes four planar segments 11 and four arc segments 12, which are arranged alternately along the circumference to form a square tube structure. The widths of the four planar segments 11 are all equal, and the curvatures of the four arc segments 12 are also equal, making the square tube structure formed by the four planar segments 11 and the four arc segments 12 centrally symmetrical with respect to the axis O' of the main shaft 1. The ratio of the width x' of the planar segment 11 to the wall thickness t of the main shaft 1, i.e., the width-to-thickness ratio x' / t, is between 20 and 25.

[0039] It should be noted that the width-to-thickness ratio x' / t being between 20 and 25 includes cases where x' / t equals 20 and x' / t equals 25. When the width-to-thickness ratio x' / t is greater than 25, under the premise of the same material, the same type of cross section, and the same wall thickness, the curvature of the arc segment 12 decreases, resulting in a decrease in bending strength. When the width-to-thickness ratio x' / t is less than 20, under the premise of the same material, the same type of cross section, and the same wall thickness, as the curvature of the arc segment 12 increases, the plastic section modulus will decrease, and the polar moment of inertia will decrease, which will lead to a decrease in bending strength and torsional strength. Therefore, the main shaft 1 of the photovoltaic tracking bracket 100 of this utility model has an optimal width-to-thickness ratio range. Within this range, the main shaft 1 of the photovoltaic tracking bracket 100 possesses both optimal torsional strength and bending strength, achieving a balance between the two and thus obtaining better stability.

[0040] Please refer to Figures 1 to 4As shown, further, the width-to-thickness ratio x' / t is between 20 and 22.5. It should be noted that the width-to-thickness ratio x' / t being between 20 and 22.5 includes cases where x' / t equals 20 and x' / t equals 22.5. Preferably, x' / t is 22.5, at which point the bending strength and torsional strength of the main shaft 1 of the photovoltaic tracking bracket 100 of this invention achieve the best matching effect.

[0041] Please refer to Figures 1 to 4 As shown, in one embodiment, the main shaft 1 is in the shape of a square tube. Specifically, the main shaft 1 is a square tube with rounded corners; that is, based on a square tube with a square cross-section, the vertices formed by adjacent sides of the square are rounded, forming arc segments 12. The original sides of the square are rounded to form planar segments 11. The perpendicular distance between the center O of the arc segment 12 and the two adjacent planar segments 11 is equal to the radius of curvature r of the arc segment 12. The main shaft 1 uses a square tube with rounded corners to address the issue of how to ensure good torsional strength while maintaining its bending resistance. The main shaft 1 can be made of steel such as Q355, Q420, Q500, or Q550. Based on this, the radius of curvature r of the arc segment 12 can be further set to 25mm to 70mm, and / or the wall thickness t of the main shaft 1 can be set to 2mm to 3mm, and the original width x of the main shaft 1 can be set to 100mm to 200mm. The original width x of the main shaft 1 is the distance between the outer walls of the two opposite planar segments 11. This setting makes the main shaft 1 have better torsional strength and / or bending strength, and facilitates obtaining a better width-to-thickness ratio range.

[0042] Please refer to Figures 1 to 4 As shown in Embodiment 1 of the specific implementation, there are four planar segments 11 and four arc segments 12, and the arc segments 12 are located at the rounded corner positions of two adjacent planar segments 11. This further defines the main shaft 1 as a square tube in which the planar segments 11 and the arc segments 12 are arranged alternately in sequence, achieving a balance and consideration between torsional strength and bending strength, thereby having better stability.

[0043] Please refer to Figures 5 to 12As shown, in other embodiments (Embodiments 2 and 3) of the specific implementation, the main shaft 1 includes multiple shaft segments 10 that are separately arranged, and the multiple shaft segments 10 are connected end to end to form a whole. Each shaft segment 10 includes a first shaft segment 101 and a second shaft segment 102 arranged adjacent to each other; the first shaft segment 101 and the second shaft segment 102 are connected sequentially to form a whole through various methods. In other words, the main shaft 1 is a type of main shaft in which multiple separately arranged segments are then connected into a whole.

[0044] Please refer to Figures 5 to 10 As shown, the main shaft 1 includes a first shaft segment 101, a second shaft segment 102, and a connector 5. The first shaft segment 101 and the second shaft segment 102 are connected end-to-end. The first shaft segment 101 includes a first end 1011 and a second end 1012 arranged in opposite directions, and the second shaft segment 102 includes a third end 1021 and a fourth end 1022 arranged in opposite directions. The first shaft segment 101 and the second shaft segment 102 being connected end-to-end means that the second end 1012 and the third end 1021 are connected to each other in the straight direction in which the main shaft 1 extends, or the two are connected by an additional connecting structure.

[0045] Please refer to Figures 5 to 10 In the second embodiment shown, the connector 5 covers the outside of the second end and the third end 1021;

[0046] Please continue to refer to Figures 5 to 10 In the second embodiment shown, when one end of the connector 5 covers the outside of the second end 1012 and the other end covers the outside of the third end 1021, preferably, the connector 5 is a split type. The split type of connector 5 facilitates covering the shaft segment 10. However, after covering, the upper and lower pieces 51 and 52 of the split connector 5 still need to be further self-mounted and positioned using other ordinary bolts 62 to securely connect the first shaft segment 101 and the second shaft segment 102 into a single unit. Of course, in other embodiments, the connector 5 is also integrally formed. The second end 1012 is inserted into one end of the integral connector 5, and the third end 1021 is inserted into the other end of the integral connector 2. That is, the integral connector 5 covers the outside of the second end 1012 and the third end 1021, and then the long bolt 61 passes through the connector 5, the second end 1012 and the third end 1021 to realize the connection between the first shaft segment 101 and the second shaft segment 102.

[0047] Please refer to Figures 5 to 10As shown, the spindle 1 also includes a fastener 6. Specifically, in Embodiment 2, the connector 5 covers the exterior of the second end 1012 and the third end 1021, and the fastener 6 passes through the connector 5, the second end 1012, and the third end 1021. It is particularly noteworthy that the fastener 6 in Embodiment 2 is a long bolt 61. This is because the fastener 6 (long bolt 61) in Embodiment 2 extends from the upper side of the upper piece 51 to the lower side of the lower piece 52, thus having a length equivalent to the diameter of the entire spindle 1, thereby achieving the function of separate coverage and positioning connection.

[0048] Please refer to Figure 11 and Figure 12 In the illustrated embodiment three, the spindle 1 includes a first shaft segment 101 and a second shaft segment 102, but does not include the connector 5 described in embodiment two. Both the first shaft segment 101 and the second shaft segment 102 have two oppositely arranged ends, one end being a constricted end 1001 and the other end being a non-constricted receiving end 1002. The constricted end 1001 of the first shaft segment 101 is inserted into the receiving end 1002 of the second shaft segment 102. The spindle 1 in embodiment three also includes a fastener 6, which passes through the constricted end 1001 of the first shaft segment 101 and the receiving end 1002 of the second shaft segment 102. It should be noted that, in Embodiment 3, fastener 6 is also used, and the fastener 6 is the same long bolt 61 as in Embodiment 2. One end of the long bolt 61 passes through and connects the constricted end 1001 of the first shaft segment 101 and the receiving end 1002 of the second shaft segment 102, thereby achieving a fixed connection between the first shaft segment 101 and the second shaft segment 102. This embodiment sets the structures of the first shaft segment 101 and the second shaft segment 102 to be the same, which greatly improves the convenience of processing and installation.

[0049] Taking a spindle 1 as an example, spindle 1 is a square tube made of Q500 steel. The original width of spindle 1 is 100mm to 200mm. The original width x of spindle 1 is the distance between the outer walls of two opposite planar segments 11. As shown in Table 1 below, in a specific embodiment, the original width x and wall thickness t of spindle 1 are kept constant. In this embodiment, the wall thickness t is 2mm, and ST155 indicates that the original width x of spindle 1 is 155mm, where x' = x - 2r. The radius of curvature r of the arc segment 12 varies with different width-to-thickness ratios. As shown in Table 1, as the width-to-thickness ratio decreases, the bending strength initially increases gradually, but then gradually decreases after reaching a certain level. Simultaneously, with the width-to-thickness ratio decreasing, and assuming the original width x and wall thickness t of the main shaft 1 remain constant, the larger the radius of curvature r of the arc segment 12, the smaller the cross-sectional area of ​​the main shaft 1, and the torsional strength gradually decreases. While ensuring a compact cross-section for the main shaft 1, when the width-to-thickness ratio falls within the range of 20–25, and further falls within the range of 20–22.5 (as shown in Table 1, when the width-to-thickness ratio is 22.5), the corresponding radius of curvature r of the arc segment 12 is 55 mm. This provides both superior bending strength and superior torsional strength, thus better meeting the stability requirements of the main shaft 1 and ensuring the normal operation of the photovoltaic tracking bracket 100. Furthermore, when the width-to-thickness ratio is 22.5, the corresponding original width x is 155mm, the radius of curvature r of the arc segment 12 is 55mm, and the width x' of the planar segment 11 is 45mm. While meeting the requirements for bending and torsional strength, it also has a better cross-sectional size, which reduces the difficulty of processing and inspection and improves production efficiency.

[0050] Table 1

[0051]

[0052] As shown in Table 2 below, in another embodiment, based on the main shaft 1 in Table 1, the wall thickness t of the square tube is kept constant at 2mm, and the original width x of the main shaft 1 is increased to 160mm. At this time, the bending strength and torsional strength are different under different width-to-thickness ratios. Similarly, when the width-to-thickness ratio falls within the range of 20 to 25, as shown in Table 2, when the width-to-thickness ratio is 20 and 25, the radius of curvature r of the corresponding arc segment 12 is 60mm and 55mm, which has both better bending strength and better torsional strength, thereby better meeting the stability requirements of the main shaft 1 and ensuring the normal operation of the photovoltaic tracking bracket 100. Furthermore, when the width-to-thickness ratio is 20 and 25, the corresponding original width x is 160mm, the radius of curvature r of the arc segment 12 is 60mm and 55mm respectively, and the width x' of the planar segment 11 is 40mm and 50mm respectively. The original width x, the radius of curvature r of the arc segment 12 and the width x' of the planar segment 11 are all multiples of 5. While meeting the requirements for bending and torsional strength, it also has a better cross-sectional size, which reduces the difficulty of processing and inspection and improves production efficiency.

[0053] Table 2

[0054]

[0055] As shown in Table 3 below, in another embodiment, based on the main shaft 1 in Table 1, the wall thickness t of the main shaft 1 is kept constant at 2mm, and the original width x of the main shaft 1 is reduced to 150mm. Similarly, when the width-to-thickness ratio falls within the range of 20 to 25, as shown in Table 2 when the width-to-thickness ratio is 20 and 25, the radius of curvature r of the arc segment 12 is 55mm and 50mm respectively. It has both superior bending strength and superior torsional strength, thereby better meeting the stability requirements of the main shaft 1 and ensuring the normal operation of the photovoltaic tracking bracket 100. Similarly, when the width-to-thickness ratio is 20 and 25, the corresponding original width x is 150mm, the radius of curvature r of the arc segment 12 is 55mm and 50mm respectively, and the width x' of the planar segment 11 is 40mm and 50mm respectively. The original width x, the radius of curvature r of the arc segment 12 and the width x' of the planar segment 11 are all multiples of 5. While meeting the requirements of bending and torsional strength, it also has a better cross-sectional size, which reduces the difficulty of processing and inspection and improves production efficiency.

[0056] Table 3

[0057]

[0058] Combining Tables 1 and 2, it can be seen that when the width-to-thickness ratio is 22.5, 20, and 25, spindle 1 exhibits superior bending and torsional strength compared to ratios outside the 20-25 range. However, the original width x of spindle 1 in Table 2 is greater than that in Table 1, therefore, the cost of spindle 1 in Table 2 is higher than that in Table 1. The width-to-thickness ratio of spindle 1 in Table 1, at 22.5, offers both superior bending and torsional strength while also providing a better cost-performance ratio. Furthermore, referring to Tables 1 and 3, it can be seen that the bending strength and torsional strength corresponding to a width-to-thickness ratio of 22.5 in Table 1 are better than those corresponding to width-to-thickness ratios of 20 and 25 in Table 3. Therefore, although the main shaft 1 in Table 3 has a lower cost because its original width x is smaller than the original width x of the square tube in Table 1, the bending and torsional strength in Table 1 better meets the stability requirements of the main shaft 1. Therefore, combining Tables 1, 2, and 3, when the width-to-thickness ratio is 22.5, it has both superior bending and torsional strength and a smaller cross-sectional area, thus effectively balancing cost while achieving superior bending and torsional performance. It should be emphasized that the original width x and the width x' of the planar segment 11 mentioned in this utility model have different meanings.

[0059] x represents the original width of the main shaft 1, that is, the side length of the cross section of the main shaft 1 before the fillet, or the original width of the main shaft 1 is the vertical distance between the outer walls of the two opposite planar segments 11.

[0060] x' represents the width of the planar segment 11, that is, the length of the planar segment 11 of the cross-section after the main shaft 1 is rounded.

[0061] As shown in Tables 1 to 15, the variations in bending and torsional strength of the spindle 1 with original widths x of 120mm, 150mm, 155mm, 160mm, and 180mm, wall thicknesses t of 2mm, 2.5mm, and 3mm, and radius of curvature r of the arc segment 12 ranging from 25mm to 70mm, are presented, under the same material and cross-sectional shape. It is evident that within a width-to-thickness ratio range of 20 to 25, the spindle 1 exhibits both superior bending and torsional strength, high stability, and effectively balances cost.

[0062] Table 4

[0063]

[0064] Table 5

[0065]

[0066] Table 6

[0067]

[0068] Table 7

[0069]

[0070] Table 8

[0071]

[0072] Table 9

[0073]

[0074] Table 10

[0075]

[0076]

[0077] Table 11

[0078]

[0079] Table 12

[0080]

[0081] Table 13

[0082]

[0083] Table 14

[0084]

[0085]

[0086] Table 15

[0087]

[0088] In summary, the main shaft 1 of the photovoltaic tracking bracket 100 of this utility model has a compact cross-section with a width-to-thickness ratio x' / t between 20 and 25. Within this width-to-thickness ratio range, a cross-section with better performance can be obtained, exhibiting superior bending and torsional strength. This achieves a balance between torsional and bending strength and cost, resulting in better stability. Furthermore, the main shaft 1 of the photovoltaic tracking bracket 100 of this utility model has superior cross-sectional dimensions, which simplifies the processing technology, reduces the difficulty of processing and inspection during the manufacturing process, and improves production efficiency.

[0089] The above embodiments are only used to illustrate the present utility model and are not intended to limit the technical solutions described in the present utility model. The understanding of the present utility model should be based on those skilled in the art. Although the present utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to the present utility model. All technical solutions and improvements that do not depart from the spirit and scope of the present utility model should be covered within the scope of the claims of the present utility model.

Claims

1. A main shaft for a photovoltaic tracking bracket, characterized in that: The cross-section of the main shaft is a compact cross-section, which includes four planar segments (11) and four arc segments (12). The four planar segments (11) and four arc segments (12) are arranged alternately along the circumference to form a square tubular structure. The widths of the four planar segments (11) are all equal and the curvatures of the four arc segments (12) are also equal, so that the square tubular structure formed by the four planar segments (11) and the four arc segments (12) is a centrally symmetrical figure with respect to the axis of the main shaft. The ratio of the width x' of the planar segment (11) to the wall thickness t of the main shaft, i.e., the width-to-thickness ratio x' / t, is between 20 and 25.

2. The main shaft of the photovoltaic tracking bracket as described in claim 1, characterized in that: The width-to-thickness ratio x' / t is between 20 and 22.

5.

3. The main shaft of the photovoltaic tracking bracket as described in claim 1, characterized in that: The spindle is made of Q355 steel, Q420 steel, Q500 steel or Q550 steel.

4. The main shaft of the photovoltaic tracking bracket as described in claim 1, characterized in that: The radius of curvature r of the arc segment (12) is 25mm to 70mm.

5. The main shaft of the photovoltaic tracking bracket as described in claim 1, characterized in that: The wall thickness t of the spindle is 2mm to 3mm.

6. The main shaft of the photovoltaic tracking bracket as described in claim 1, characterized in that: The original width x of the spindle is the vertical distance between the outer walls of the two opposing planar segments (11), and the radius of curvature of the arc segment (12) is r, where x' = x - 2r, and the original width x of the spindle is 100mm to 200mm.

7. The main shaft of the photovoltaic tracking bracket as described in any one of claims 1 to 6, characterized in that: The main shaft includes multiple shaft segments (10) that are separately arranged, and the multiple shaft segments (10) are connected end to end to form a whole.

8. The main shaft of the photovoltaic tracking bracket as described in claim 7, characterized in that: The spindle includes a first shaft segment (101), a second shaft segment (102), and a connector (5). The first shaft segment (101) and the second shaft segment (102) are connected end to end. The first shaft segment (101) includes a first end (1011) and a second end (1012) arranged opposite to each other. The second shaft segment (102) includes a third end (1021) and a fourth end (1022) arranged opposite to each other. The second end (1012) and the third end (1021) are arranged close to each other in the straight direction of the spindle extension. The connector (5) covers the outside of the second end (1012) and the third end (1021).

9. The main shaft of the photovoltaic tracking bracket as described in claim 8, characterized in that: The connector (5) can be either a separate piece or an integral piece.

10. The main shaft of the photovoltaic tracking bracket as described in claim 8, characterized in that: The spindle also includes a fastener (6), the connector (5) covers the outside of the second end (1012) and the third end (1021), and the fastener (6) passes through the connector (5), the second end (1012) and the third end (1021).

11. The main shaft of the photovoltaic tracking bracket as described in claim 8, characterized in that: The spindle includes a first shaft segment (101), a second shaft segment (102), and a fastener (6). The first shaft segment (101) and the second shaft segment (102) each include a constricted end (1001) and a non-constricted receiving end (1002) arranged oppositely. The constricted end (1001) of the first shaft segment (101) is inserted into the receiving end (1002) of the second shaft segment (102). The fastener (6) passes through the constricted end (1001) of the first shaft segment (101) and the receiving end (1002) of the second shaft segment (102).

12. A photovoltaic tracking bracket, comprising a column (2), a driving device (3), and purlins (4), characterized in that; Includes the main shaft of the photovoltaic tracking bracket as described in any one of claims 1-11, wherein the main shaft of the photovoltaic tracking bracket is mounted on the top of the column (2), the purlin (4) is mounted on the main shaft of the photovoltaic tracking bracket to support the photovoltaic module, and the driving end of the driving device (3) is connected to the main shaft of the photovoltaic tracking bracket to drive the main shaft of the photovoltaic tracking bracket to rotate.

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