A four-section lifting column

Abstract

The present invention discloses a four-section lifting column, including a lifting assembly and four lifting tubes connected with each other, the four lifting tubes are the first lifting tube, the second lifting tube, the third lifting tube and the fourth lifting tube from the inside to the outside, the lifting assembly includes three screw rod assemblies and a driving assembly that drives the three screw rod assemblies to operate at the same time, the lifting assembly is fixed in the second lifting tube, and the three screw rod assemblies are respectively connected in the first lifting tube, the third lifting tube and the fourth lifting tube; or, the lifting assembly is fixed in the third lifting tube, and the three screw rod assemblies are respectively connected in the first lifting tube, the second lifting tube and the fourth lifting tube. The present invention drives the three screw rod assemblies at the same time through the driving assembly, and the three screw rod assemblies respectively drive different lifting tubes upward or downward away from the lifting tube fixed with the driving assembly, so that the four lifting tubes of the lifting column can rise visually at the same time, thereby improving the overall lifting speed of the lifting column.

Description

Technical Field

[0001] The invention belongs to the field of lifting columns, and in particular relates to a four-section lifting column. Background Art

[0002] At present, the driving assembly in the existing lifting column realizes the lifting of the lifting column by driving a single screw rod assembly, which makes the lifting speed of the lifting column too slow, and it takes too long to lift to a specified height, the lifting efficiency is low, and the lifting tube of each section of the lifting column needs to be set long enough to achieve lifting to the set height, so that the length of the lifting column in the retracted state is too long, which is not convenient for storage and transportation. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a four-section lifting column that can be lifted and lowered quickly.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: a four-section lifting column, including a lifting assembly and four lifting tubes connected with each other, the four lifting tubes are the first lifting tube, the second lifting tube, the third lifting tube and the fourth lifting tube from the inside to the outside, the lifting assembly includes three screw rod assemblies and a driving assembly that drives the three screw rod assemblies to operate simultaneously, the lifting assembly is fixed in the second lifting tube, and the three screw rod assemblies are respectively connected to the first lifting tube, the third lifting tube and the fourth lifting tube; or, the lifting assembly is fixed in the third lifting tube, and the three screw rod assemblies are respectively connected to the first lifting tube, the second lifting tube and the fourth lifting tube.

[0005] Furthermore, the lifting assembly is fixed in the third lifting tube, and the three screw assemblies are respectively an upper transmission inner screw assembly connected to the second lifting tube, an upper transmission outer screw assembly connected to the first lifting tube, and a lower transmission screw assembly connected to the fourth lifting tube. The upper transmission inner screw assembly and the upper transmission outer screw assembly rotate together through splines.

[0006] Furthermore, the upper transmission inner screw assembly includes an upper transmission inner screw connected to the driving assembly and an upper transmission inner nut threadedly connected to the upper transmission inner screw, the upper transmission inner nut is connected to the second lifting tube, the upper transmission outer screw assembly includes an upper transmission outer screw and an upper transmission outer nut threadedly connected to the upper transmission outer screw, the upper transmission outer screw is sleeved on the upper transmission inner screw and rotates together with the upper transmission inner screw, and the upper transmission outer nut is connected to the first lifting tube.

[0007] Furthermore, the lower transmission screw assembly includes a lower transmission tube, a lower transmission outer screw that rotates together with the lower transmission tube through a spline to push the fourth lifting tube down, and a lower transmission outer nut threadedly connected to the lower transmission outer screw, and the lower transmission outer nut is fixed on the third lifting tube.

[0008] Furthermore, the lower transmission screw assembly includes a lower transmission inner screw connected to the fourth lifting tube and a lower transmission inner nut threadedly connected to the lower transmission inner screw, and the driving assembly is connected to the lower transmission inner nut and drives the lower transmission inner nut to rotate.

[0009] Furthermore, the lifting assembly is fixed in the second lifting tube, and the three screw assemblies are respectively an upper transmission screw assembly connected to the first lifting tube, a lower transmission outer screw assembly connected to the third lifting tube, and a lower transmission inner screw assembly connected to the fourth lifting tube. The upper transmission screw assembly includes an upper transmission inner screw and an upper transmission inner nut threadedly connected to the upper transmission inner screw, the upper transmission inner nut is connected to the first lifting tube, and the lower transmission outer screw assembly and the lower transmission inner screw assembly rotate together through a spline.

[0010] Furthermore, the lower transmission external screw assembly includes a lower transmission tube, a lower transmission external screw that rotates together with the lower transmission tube to push the third lifting tube down, and a lower transmission external nut threadedly connected to the lower transmission external screw, and the lower transmission external nut is fixed on the second lifting tube.

[0011] Furthermore, the lower transmission inner screw assembly includes a lower transmission inner screw connected to the fourth lifting tube and a lower transmission inner nut threadedly connected to the lower transmission inner screw, the lower transmission outer screw is sleeved on the outside of the lower transmission inner screw, and the lower transmission inner nut is fixed to the bottom of the lower transmission outer screw and linked to the lower transmission outer screw.

[0012] Furthermore, the driving assembly includes a motor and a reduction box that drives three screw assemblies. The reduction box includes a worm gear device connected to the motor and a first transmission device and a second transmission device connected to the screw assembly. The second transmission device and the worm gear device are driven by the first transmission device.

[0013] Furthermore, the worm gear device includes a worm connected to the motor and a worm wheel connected to the worm, the first transmission device includes a first bevel gear connected to the worm wheel, a second bevel gear meshing with the first bevel gear, and a first transmission gear linked to the second bevel gear, and the second transmission device includes a second transmission gear meshing with the first transmission gear.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] By setting a four-section lifting column, when the driving assembly drives the three screw rod assemblies to rotate at the same time, the three screw rod assemblies respectively drive different lifting tubes upward or downward away from the lifting tube of the fixed driving assembly, so that the four lifting tubes of the lifting column can visually rise at the same time, so that the lifting speed of the lifting column is multiple times that of the lifting column of a single screw rod assembly. When the output speed of the screw rod assembly is low, the overall lifting speed of the lifting column is improved, and the different lifting tubes of the four-section lifting column move upward or downward when the lifting column is started. When the lifting column is in a retracted state, the four lifting tubes overlap or partially overlap. Each lifting tube does not need to be set too long to realize the lifting and lowering of the lifting column to the set height, that is, the purpose of low installation distance and high stroke is achieved, which is convenient for the storage and transportation of the lifting column.

[0016] The features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0018] Figure 1 It is a three-dimensional diagram of the first embodiment;

[0019] Figure 2 A cross-sectional view of the first embodiment Figure 1 ;

[0020] Figure 3 A cross-sectional view of the first embodiment Figure 2 ;

[0021] Figure 4 A cross-sectional view of the second embodiment Figure 1 ;

[0022] Figure 5 A cross-sectional view of the second embodiment Figure 2 ;

[0023] Figure 6 The cross-sectional view of the third embodiment Figure 1 ;

[0024] Figure 7 The cross-sectional view of the third embodiment Figure 2 ;

[0025] Figure 8 Schematic diagram of the reduction box in Example 1 Figure 1 ;

[0026] Fig. 9 Schematic diagram of the reduction box in Example 1 Figure 2 . Description of the drawings:

[0028] 110, first lifting tube; 120, second lifting tube; 130, third lifting tube; 140, fourth lifting tube;

[0029] 200, motor;

[0030] 300, reduction box; 311, worm gear; 312, worm; 321, first bevel gear; 322, second bevel gear; 323, first transmission gear; 331, second transmission gear;

[0031] 410, upper transmission inner screw rod; 420, upper transmission inner nut;

[0032] 510, upper transmission outer screw rod; 520, upper transmission outer nut; 530, upper transmission tube;

[0033] 610, lower transmission inner screw rod; 620, lower transmission inner nut;

[0034] 710, lower transmission outer screw rod; 720, lower transmission outer nut; 730, lower transmission tube.

[0035] 810, first spline; 820, second spline. DETAILED DESCRIPTION

[0036] A four-section lifting column comprises a lifting assembly and four lifting tubes which are connected with each other. The four lifting tubes are a first lifting tube, a second lifting tube, a third lifting tube and a fourth lifting tube from the inside to the outside. The lifting assembly comprises three screw rod assemblies and a driving assembly which drives the three screw rod assemblies to operate simultaneously. The lifting assembly is fixed in the second lifting tube, and the three screw rod assemblies are respectively connected in the first lifting tube, the third lifting tube and the fourth lifting tube; or the lifting assembly is fixed in the third lifting tube, and the three screw rod assemblies are respectively connected in the first lifting tube, the second lifting tube and the fourth lifting tube. The present invention provides four-section lifting columns, and when the driving assembly drives the three screw rod assemblies to rotate at the same time, the three screw rod assemblies respectively drive different lifting tubes upward or downward away from the lifting tube of the fixed driving assembly, so that the four lifting tubes of the lifting column can visually rise at the same time, so that the lifting speed of the lifting column is multiple times that of the lifting column of the single screw rod assembly. When the output speed of the screw rod assembly is low, the overall lifting speed of the lifting column is improved, and the different lifting tubes of the four-section lifting columns move upward or downward when the lifting column is started, and the four-section lifting tubes overlap or partially overlap when the lifting column is in a retracted state. Each lifting tube does not need to be set too long to realize the lifting of the lifting column to a set height, that is, the purpose of low installation distance and high stroke is achieved, which is convenient for the storage and transportation of the lifting column.

[0037] The technical solutions of the embodiments of the present invention are explained and described below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0038] 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", "clockwise", "counterclockwise" 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, rather than indicating or implying 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 limiting the present invention.

[0039] 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, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0040] 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 connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0042] Embodiment 1:

[0043] A four-section lifting column, such as Figures 1 to 3 As shown, it includes a lifting assembly and four lifting tubes that are connected to each other. The lifting assembly drives the four lifting tubes to extend and retract. The four lifting tubes are, from the inside to the outside, the first lifting tube 110, the second lifting tube 120, the third lifting tube 130 and the fourth lifting tube 140. The lifting assembly includes three screw assemblies and a driving assembly that drives the three screw assemblies to operate simultaneously.

[0044] The lifting assembly in this embodiment is fixed in the third lifting tube 130 and connected to the bottom wall of the third lifting tube 130. The three screw assemblies are an upper transmission inner screw assembly connected to the second lifting tube 120, an upper transmission outer screw assembly connected to the first lifting tube 110, and a lower transmission screw assembly connected to the fourth lifting tube 140. The upper transmission inner screw assembly and the upper transmission outer screw assembly rotate together through the first spline 810.

[0045] In this embodiment, Figure 8 and Fig. 9 As shown, the drive assembly includes a motor 200 that is powered on and rotated and a reduction box 300 that drives three screw assemblies, the reduction box 300 includes a worm gear device connected to the output shaft of the motor 200, the worm gear device includes a worm 312 connected to the motor 200 and a worm wheel 311 connected to the worm 312, the rotation output of the motor 200 is decelerated, and the speed of the screw assembly is controlled within a suitable range, the reduction box 300 also includes a first transmission device and a second transmission device, the second transmission device and the worm gear device are driven by the first transmission device, so that the worm gear device can simultaneously drive the first transmission device and the second transmission device to rotate without being connected to both at the same time, thereby reducing the volume of the worm gear device. In this embodiment, preferably, the first transmission device includes a first bevel gear 321 keyed to the worm wheel 311, a second bevel gear 322 meshed with the first bevel gear 321, and a first transmission gear 323 linked to the second bevel gear 322, and the second transmission device includes a second transmission gear 331 meshed with the first transmission gear 323.

[0046] In this embodiment, the upper transmission inner screw assembly includes an upper transmission inner screw 410 whose bottom is plugged into the second bevel gear 322 and rotates with the second bevel gear 322, and an upper transmission inner nut 420 threadedly connected to the upper transmission inner screw 410, and the upper transmission inner nut 420 is connected to the second lifting tube 120. The upper transmission outer screw assembly includes an upper transmission outer screw 510 and an upper transmission outer nut 520 threadedly connected to the upper transmission outer screw 510, the upper transmission outer screw 510 is sleeved on the upper transmission inner screw 410, the upper transmission outer screw 510 rotates together with the upper transmission inner screw 410 through the first spline 810 at the top, and the upper transmission outer nut 520 is connected to the first lifting tube 110. Preferably, the first lifting tube 110 includes a first tube body and a top plate arranged on the first tube body, the upper transmission outer nut 520 is connected to the top plate through the upper transmission tube 530, and the upper transmission outer nut 520 is fixed inside the upper transmission tube 530.

[0047] In this embodiment, the lower transmission screw assembly includes a lower transmission tube 730 connected to the second transmission gear 331, a lower transmission external screw 710, and a lower transmission external nut 720 threadedly connected to the lower transmission external screw 710. The lower transmission external nut 720 is fixed on the reduction box 300, that is, fixed on the third lifting tube 130. The lower transmission tube 730 is sleeved on the outside of the lower transmission external screw 710, and rotates together with the lower transmission tube 730 through the second spline 820 on the top of the lower transmission external screw 710 to push the fourth lifting tube 140 to descend relative to the third lifting tube 130.

[0048] The working process of the lifting column is as follows:

[0049] The output shaft of the motor 200 rotates to drive the worm 312 to rotate, and the worm 312 drives the worm wheel 311 to rotate to reduce the rotation speed. The worm wheel 311 drives the first bevel gear 321 to rotate, and the first bevel gear 321 drives the second bevel gear 322 to rotate. The second bevel gear 322 drives the upper transmission inner screw 410 to rotate. The upper transmission inner screw 410 rotates to drive the upper transmission inner nut 420 to move axially along the upper transmission inner screw 410. The upper transmission inner nut 420 drives the second lifting tube 120 to move above the third lifting tube 130 and pushes the upper transmission outer screw 510 upward. When the upper transmission inner screw 410 rotates, the upper transmission outer screw 510 rotates together with the upper transmission inner screw 410, driving the upper transmission outer nut 520 to move axially along the upper transmission outer screw 510. The upper transmission outer nut 520 pushes the first lifting tube 110 upward through the upper transmission tube 530, so that the first lifting tube 110 moves upward relative to the second lifting tube 120.

[0050] When the second bevel gear 322 drives the upper transmission inner screw 410 to rotate, the second bevel gear 322 also drives the first transmission gear 323 coaxially rotating with the second bevel gear 322 to rotate, the first transmission gear 323 drives the second transmission gear 331 meshing with the first transmission gear 323 to rotate, the second transmission gear 331 drives the lower transmission tube 730 to rotate, and the lower rotating tube drives the lower transmission outer screw 710 to rotate through the second spline 820. Because the lower transmission outer nut 720 is fixed on the third lifting tube 130, the lower transmission outer screw 710 is rotated relative to the lower transmission outer nut 720. The lower transmission outer screw rod 710 pushes the bottom plate of the fourth lifting tube 140 toward the lower part of the third lifting tube 130 through the connecting structure. The lower transmission outer screw rod 710 and the connecting structure are fixed in the axial direction, but can rotate relative to each other (the connecting structure can be the structure shown in the figure, or it can be any structure such as a bearing to achieve this function), so that the lower transmission outer screw rod 710 does not drive the fourth lifting tube 140 to rotate. When the fourth lifting tube 140 is set on the platform, it visually forms the effect that the first lifting tube 110, the second lifting tube 120 and the third lifting tube 130 move upward at the same time.

[0051] By setting a four-section lifting column, when the driving assembly drives the three screw rod assemblies to rotate at the same time, the three screw rod assemblies respectively drive different lifting tubes upward or downward away from the lifting tube of the fixed driving assembly, so that the four lifting tubes of the lifting column can visually rise at the same time, so that the lifting speed of the lifting column is multiple times that of the lifting column of a single screw rod assembly. When the output speed of the screw rod assembly is low, the overall lifting speed of the lifting column is improved, and the different lifting tubes of the four-section lifting column move upward or downward when the lifting column is started. When the lifting column is in a retracted state, the four lifting tubes overlap or partially overlap. Each lifting tube does not need to be set too long to realize the lifting and lowering of the lifting column to the set height, that is, the purpose of low installation distance and high stroke is achieved, which is convenient for the storage and transportation of the lifting column.

[0052] Embodiment 2:

[0053] The difference between this embodiment and the first embodiment is that Figure 4 and Figure 5 As shown, the lower transmission screw assembly includes a lower transmission inner screw 610 connected to the fourth lifting tube 140 and a lower transmission inner nut 620 threadedly connected to the lower transmission inner screw 610. The lower transmission inner nut 620 is arranged in the third lifting tube 130. The first transmission gear 323 is connected to the lower transmission inner nut 620 through the second transmission gear 331 and drives the lower transmission inner nut 620 to rotate. The second transmission gear 331 is sleeved on the outer side of the lower transmission inner nut 620 and is linked to the lower transmission inner nut 620. It can be understood that the second transmission gear 331 can be separately arranged with the lower transmission inner nut 620 or can be arranged integrally with the lower transmission inner nut 620. The structure is simple and easy to produce.

[0054] The differences between the working process of the lifting column in this embodiment and the first embodiment are as follows:

[0055] The lower transmission inner nut 620 rotates with the first transmission gear 323, and the lower transmission inner nut 620 does not move in the vertical direction in the third lifting tube 130. The lower transmission inner screw rod 610 is connected to the bottom plate of the fourth lifting tube 140, so that the lower transmission inner screw rod 610 pushes the fourth lifting tube 140 axially to move downward from the third lifting tube 130.

[0056] Embodiment three:

[0057] The difference between this embodiment and the first embodiment is that Figure 6 and Figure 7 As shown, the lifting assembly is fixed on the bottom plate of the second lifting tube 120, and the three screw assemblies are respectively an upper transmission screw assembly connected to the first lifting tube 110, a lower transmission outer screw assembly connected to the third lifting tube 130, and a lower transmission inner screw assembly connected to the fourth lifting tube 140. The lower transmission outer screw assembly and the lower transmission inner screw assembly rotate together through the second spline 820.

[0058] In this embodiment, the upper transmission screw assembly includes an upper transmission inner screw 410 inserted into the second bevel gear 322 and an upper transmission inner nut 420 threadedly connected to the upper transmission inner screw 410. The upper transmission inner nut 420 is connected to the top plate of the first lifting tube 110 through an upper transmission tube 530. The upper transmission inner screw 410 rotates together with the second bevel gear 322, so that the upper transmission inner nut 420 moves upward in the axial direction, and pushes the first lifting tube 110 toward the top of the second lifting tube 120 through the upper transmission tube 530, so that the first lifting tube 110 moves upward relative to the second lifting tube 120.

[0059] In this embodiment, the lower transmission external screw assembly includes a lower transmission tube 730 connected to the second transmission gear 331, a lower transmission external screw 710 that rotates together with the lower transmission tube 730 to push the third lifting tube 130 down, and a lower transmission external nut 720 threadedly connected to the lower transmission external screw 710, and the lower transmission external nut 720 is fixed on the second lifting tube 120. The lower transmission inner screw assembly includes a lower transmission inner screw 610 connected to the fourth lifting tube 140 and a lower transmission inner nut 620 threadedly connected to the lower transmission inner screw 610, the lower transmission outer screw 710 is sleeved on the outer side of the lower transmission inner screw 610, the lower transmission inner nut 620 is fixed to the bottom of the lower transmission outer screw 710 and linked with the lower transmission outer screw 710, the lower transmission tube 730 and the top of the lower transmission outer screw 710 are transmitted through the second spline 820, the lower transmission inner screw 610 can be connected to the bottom wall of the fourth lifting tube 140 through a connecting structure, the lower transmission inner screw 610 and the connecting structure are fixed in the axial direction, but can rotate relative to each other (the connecting structure can be the structure shown in the figure, or it can be any structure such as a bearing to achieve this function), so that the lower transmission inner screw 610 does not drive the fourth lifting tube 140 to rotate.

[0060] The working process of the lifting column in this embodiment is as follows:

[0061] When the reduction box is working, the upper transmission inner screw 410 rotates together with the second bevel gear 322, so that the upper transmission inner nut 420 moves upward along the axial direction, and pushes the first lifting tube 110 toward the top of the second lifting tube 120 through the upper transmission tube 530, so that the first lifting tube 110 moves upward relative to the second lifting tube 120.

[0062] At the same time, the second bevel gear 322 drives the second transmission gear 331 to rotate, and the rotation of the second transmission gear 331 drives the lower transmission tube 730 to rotate. The lower transmission tube 730 drives the lower transmission outer screw rod 710 to rotate through the second spline 820. Because the lower transmission outer nut 720 is fixed to the second lifting tube 120 and does not move up and down, the lower transmission outer screw rod 710 axially pushes the bottom wall of the third lifting tube 130, so that the third lifting tube 130 moves downward from the second lifting tube 120; when the lower transmission outer screw rod 710 rotates, the lower transmission inner nut 620 fixed at the bottom of the lower transmission outer screw rod 710 rotates and descends together with the lower transmission outer screw rod 710, so that the lower transmission inner screw rod 610 axially pushes the fourth lifting tube 140, so that the fourth lifting tube 140 moves downward from the third lifting tube 130.

[0063] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A four-section lifting column, characterized in that: The lifting assembly comprises a lifting assembly and four lifting tubes which are connected with each other. The four lifting tubes are, from the inside to the outside, a first lifting tube, a second lifting tube, a third lifting tube and a fourth lifting tube. The lifting assembly comprises three screw rod assemblies and a driving assembly which drives the three screw rod assemblies to operate simultaneously. The lifting assembly is fixed in the second lifting tube, and the three screw rod assemblies are respectively connected in the first lifting tube, the third lifting tube and the fourth lifting tube; or, the lifting assembly is fixed in the third lifting tube, and the three screw rod assemblies are respectively connected in the first lifting tube, the second lifting tube and the fourth lifting tube; the lifting assembly is fixed in the third lifting tube, and the three screw rod assemblies are respectively an upper transmission inner screw rod assembly connected to the second lifting tube, an upper transmission outer screw rod assembly connected to the first lifting tube and a lower transmission screw rod assembly connected to the fourth lifting tube, and the upper transmission inner screw rod assembly and the upper transmission outer screw rod assembly rotate together through a spline; the upper transmission inner screw rod assembly The screw assembly includes an upper transmission inner screw connected to the driving assembly and an upper transmission inner nut threadedly connected to the upper transmission inner screw, the upper transmission inner nut is connected to the second lifting tube, the upper transmission outer screw assembly includes an upper transmission outer screw and an upper transmission outer nut threadedly connected to the upper transmission outer screw, the upper transmission outer screw is sleeved on the upper transmission inner screw and rotates together with the upper transmission inner screw, and the upper transmission outer nut is connected to the first lifting tube; the lower transmission screw assembly includes a lower transmission tube, a lower transmission outer screw that rotates together with the lower transmission tube through a spline to push the fourth lifting tube to descend, and a lower transmission outer nut threadedly connected to the lower transmission outer screw, and the lower transmission outer nut is fixed on the third lifting tube; the lower transmission screw assembly includes a lower transmission inner screw connected to the fourth lifting tube and a lower transmission inner nut threadedly connected to the lower transmission inner screw, the driving assembly is connected to the lower transmission inner nut and drives the lower transmission inner nut to rotate; When the reduction box is working, the upper transmission inner screw rotates together with the second bevel gear, so that the upper transmission inner nut moves upward along the axial direction, and pushes the first lifting tube to the top of the second lifting tube through the upper transmission tube, so that the first lifting tube moves upward relative to the second lifting tube; At the same time, the second bevel gear drives the second transmission gear to rotate, and the rotation of the second transmission gear drives the lower transmission tube to rotate. The lower transmission tube drives the lower transmission outer screw to rotate through the second spline. Because the lower transmission outer nut is fixed to the second lifting tube and does not move up and down, the lower transmission outer screw pushes the bottom wall of the third lifting tube axially, so that the third lifting tube moves below the second lifting tube.

2. A four-section lifting column according to claim 1, characterized in that: The lifting assembly is fixed in the second lifting tube, and the three screw assemblies are respectively an upper transmission screw assembly connected to the first lifting tube, a lower transmission outer screw assembly connected to the third lifting tube, and a lower transmission inner screw assembly connected to the fourth lifting tube. The upper transmission screw assembly includes an upper transmission inner screw and an upper transmission inner nut threadedly connected to the upper transmission inner screw, the upper transmission inner nut is connected to the first lifting tube, and the lower transmission outer screw assembly and the lower transmission inner screw assembly rotate together through a spline.

3. A four-section lifting column according to claim 2, characterized in that: The lower transmission outer screw assembly includes a lower transmission tube, a lower transmission outer screw that rotates together with the lower transmission tube to push the third lifting tube down, and a lower transmission outer nut threadedly connected to the lower transmission outer screw, and the lower transmission outer nut is fixed on the second lifting tube.

4. A four-section lifting column according to claim 3, characterized in that: The lower transmission inner screw assembly includes a lower transmission inner screw connected to the fourth lifting tube and a lower transmission inner nut threadedly connected to the lower transmission inner screw, the lower transmission outer screw is sleeved on the outside of the lower transmission inner screw, and the lower transmission inner nut is fixed to the bottom of the lower transmission outer screw and linked to the lower transmission outer screw.

5. The four-section lifting column according to claim 1, characterized in that: The driving assembly includes a motor and a reduction box that drives three screw assemblies. The reduction box includes a worm gear device connected to the motor and a first transmission device and a second transmission device connected to the screw assembly. The second transmission device and the worm gear device are driven by the first transmission device.

6. A four-section lifting column according to claim 5, characterized in that: The worm gear device includes a worm connected to the motor and a worm wheel connected to the worm, the first transmission device includes a first bevel gear connected to the worm wheel, a second bevel gear meshing with the first bevel gear, and a first transmission gear linked to the second bevel gear, and the second transmission device includes a second transmission gear meshing with the first transmission gear.

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