A multi-stage electric cylinder

Abstract

The application provides a multi-stage electric cylinder, which comprises a driving mechanism and a telescopic assembly; the telescopic assembly comprises a plurality of coaxially nested lead screws and a plurality of coaxially nested lifting rods; adjacent two lead screws can slide relative to each other along the axial direction of the lead screw, and adjacent two lifting rods can slide relative to each other along the axial direction of the lifting rod; the outermost lead screw is located inside the innermost lifting rod; the lead screw and the lifting rod are connected through internal-external cross thread cooperation; the innermost lead screw and the outermost lifting rod are connected through a threaded pair, the outermost lead screw and the innermost lifting rod are connected through a threaded pair, and each intermediate lead screw is connected with the corresponding lifting rod through a threaded pair; the innermost lead screw is connected with the driving mechanism; when the driving mechanism drives the innermost lead screw to rotate, the driving force output by the driving mechanism is transmitted from the innermost lead screw to the outermost lead screw and drives each lifting rod to realize synchronous telescopic motion through the threaded pair between each lead screw and the corresponding lifting rod.

Description

Technical Field

[0001] This invention relates to the field of electric cylinder technology. More specifically, it relates to a multi-stage electric cylinder. Background Technology

[0002] An electric cylinder is an electromechanical actuator that converts the rotary motion of a motor into linear motion, and is widely used in industrial automation, aerospace, and automotive manufacturing. With the continuous expansion of application scenarios, increasingly stringent requirements are being placed on the installation space and stroke of electric cylinders, namely, achieving the largest possible working stroke within a limited space. To address this challenge, a multi-stage electric cylinder has been designed. The multi-stage electric cylinder employs a nested sleeve structure, using a multi-stage screw-nut transmission pair to maintain a compact axial dimension in the retracted state and achieve a stroke several times its own length in the extended state.

[0003] Currently, existing multi-stage electric cylinders employ a series transmission mode from the outside in. For example, in a spline-driven multi-stage electric cylinder, the inner cavity of the outer sleeve contains a second-stage sleeve, and the inner cavity of the hollow piston rod contains a second-stage hollow lead screw threaded to a second-stage nut. A first-stage sleeve is embedded within the second-stage hollow lead screw. The pneumatic power transmission path is as follows: power is input from the outer sleeve side and transmitted step-by-step inward to each stage of sleeve and lead screw. Another example is a range-extending electric cylinder in the prior art, which transmits the power of the drive motor to the spline shaft inside the lead screw via a first and second gear, causing the spline shaft to rotate and thus moving the telescopic sleeve axially. This scheme also employs a step-by-step transmission mode from the outside in.

[0004] However, the existing technologies mentioned above have the following shortcomings: 1. Large radial dimension. Since power is transmitted step by step from the outermost layer inwards, each stage requires corresponding nuts, bearings, and transmission components. These components are stacked radially, making it difficult to further reduce the overall radial dimension of the electric cylinder, thus failing to meet the needs of certain space-constrained applications. 2. Long transmission chain. In the series transmission mode from the outside inwards, power needs to be transmitted through multiple stages to reach the innermost actuator. The longer the transmission chain, the greater the cumulative transmission error and the greater the loss of transmission efficiency. 3. Structural load. To achieve step-by-step power transmission, each stage requires independent nuts, bearings, and corresponding connection structures, resulting in a large number of parts, high assembly difficulty, and high manufacturing costs. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-stage electric cylinder to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a multi-stage electric cylinder, comprising: Drive mechanism and telescopic components; The telescopic assembly includes multiple lead screws and multiple lifting rods arranged coaxially and nested together. Two adjacent lead screws can slide relative to each other along the lead screw axis, and two adjacent lifting rods can slide relative to each other along the lifting rod axis; The outermost lead screw is located inside the innermost lifting rod; The lead screw and the lifting rod are connected by an inner and outer cross threaded engagement; the innermost lead screw and the outermost lifting rod are connected by a threaded pair, and the outermost lead screw and the innermost lifting rod are connected by a threaded pair. Each of the middle lead screws is connected to its corresponding lifting rod by a threaded pair. The innermost lead screw is connected to the drive mechanism for transmission; when the drive mechanism drives the innermost lead screw to rotate, the driving force output by the drive mechanism is transmitted from the innermost lead screw to the outermost lead screw and drives each lifting rod to achieve synchronous extension and retraction through the threaded pair between each lead screw and the corresponding lifting rod.

[0007] The preferred embodiment is that each lead screw passes through the bottom wall of the lifting rod that is threadedly engaged with the lead screw along its own axial direction; and except for the innermost lifting rod, the inner surface of the bottom wall of each of the other lifting rods also abuts against the bottom end of the adjacent lead screw located outside the lead screw that is threadedly engaged with the lifting rod.

[0008] In a preferred embodiment, each lead screw drives the corresponding lifting rod to generate axial displacement through a threaded pair; when each lifting rod moves axially, it synchronously drives the lead screw that abuts it to generate axial displacement; the rotational drive of the lead screw and the axial drive of the lifting rod work together to realize the synchronous extension and retraction of each level of lifting rod.

[0009] A preferred embodiment is that the lead screw and the lifting rod are coaxially arranged and the number of lead screws and lifting rods is equal.

[0010] A preferred embodiment is that a first connecting structure is provided between two adjacent lead screws; the first connecting structure is a spline connection structure; the first connecting structure is used to transmit circumferential torque between the lead screws and allow axial relative displacement between the lead screws.

[0011] A preferred embodiment is that a second connecting structure is provided between two adjacent lifting rods; the second connecting structure is a spline connection structure; the second connecting structure is used to restrict the relative rotation between each lifting rod, while allowing axial relative sliding between each lifting rod.

[0012] In a preferred embodiment, the multi-stage electric cylinder further includes a cylinder barrel for accommodating the drive mechanism and the telescopic assembly, the cylinder barrel being fitted over the outermost lifting rod; a guide structure is provided between the cylinder barrel and the outermost lifting rod, the guide structure being used to restrict the rotation of the outermost lifting rod relative to the cylinder barrel and to allow the outermost lifting rod to slide along its own axial direction.

[0013] In a preferred embodiment, the drive mechanism is a servo motor; the output shaft of the drive mechanism transmits the rotational motion to the innermost lead screw through a gear transmission pair.

[0014] The preferred embodiment is that the telescopic assembly is a three-stage telescopic structure; the telescopic assembly includes a first-stage lead screw, a second-stage lead screw and a third-stage lead screw arranged sequentially from the inside to the outside, and a first-stage lifting rod, a second-stage lifting rod and a third-stage lifting rod arranged sequentially from the inside to the outside; The third-stage lead screw is located inside the first-stage lifting rod; the first-stage lead screw is connected to the drive mechanism, the third-stage lifting rod is engaged with the first-stage lead screw through a threaded pair, the first-stage lifting rod is engaged with the third-stage lead screw through a threaded pair, and the second-stage lifting rod is engaged with the second-stage lead screw through a threaded pair.

[0015] The preferred embodiment is that, except for the innermost lead screw, all other lead screws are hollow cylindrical structures; all the lifting rods are hollow cylindrical structures.

[0016] The beneficial effects of this invention are as follows: This invention provides a multi-stage electric cylinder including a drive mechanism and a telescopic assembly. The telescopic assembly includes multiple lead screws and multiple lifting rods coaxially nested together. Adjacent lead screws can slide relative to each other along their axial direction, and adjacent lifting rods can slide relative to each other along their axial direction. The outermost lead screw is located inside the innermost lifting rod. The lead screws and lifting rods are connected by interlocking threads. The innermost lead screw and the outermost lifting rod are connected by a threaded pair, and the outermost lead screw and the innermost lifting rod are also connected by a threaded pair. Each intermediate lead screw is connected to its corresponding lifting rod by a threaded pair. The innermost lead screw is connected to the drive mechanism. When the drive mechanism drives the innermost lead screw to rotate, the driving force output by the drive mechanism is transmitted from the innermost lead screw to the outermost lead screw and drives each lifting rod to achieve synchronous telescopic movement through the threaded pairs between each lead screw and its corresponding lifting rod. The radial dimension is significantly reduced. This invention employs an inside-out power transmission path, with power input from the innermost lead screw and transmitted step-by-step outwards to drive the lifting rods at each level. Compared to the existing outside-in nested structure, the radial structure of this invention is more compact, and the radial dimension is significantly reduced, enabling a smaller installation diameter, making it particularly suitable for applications with extremely limited installation space. The direct inside-out transmission mode of this invention allows the rotational power of the drive mechanism to be transmitted step-by-step outwards only through the connection structure between each lead screw, significantly reducing intermediate transmission links and shortening the transmission chain. This reduces cumulative transmission errors and energy losses, thereby improving transmission efficiency and system response speed. This invention also eliminates the need for additional components such as intermediate nuts and bearing seats used to connect different levels of lead screws in traditional designs, reducing the number of parts, assembly difficulty, and manufacturing costs. Attached Figure Description

[0017] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the cross-sectional structure of the multi-stage electric cylinder of the present invention.

[0019] Figure 2 This is a schematic diagram of the multi-stage electric cylinder of the present invention in its extended state.

[0020] Figure 3 This is a schematic diagram of the multi-stage electric cylinder of the present invention in the retracted state.

[0021] Reference numerals: 1. Cylinder; 2. Drive mechanism; 3. Telescopic assembly; 31. First-stage lead screw; 32. Second-stage lead screw; 33. Third-stage lead screw; 34. First-stage lifting rod; 35. Second-stage lifting rod; 36. Third-stage lifting rod; 37. Reduction structure; 41. First connecting piece; 42. Second connecting piece. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0023] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0024] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0025] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0027] This invention provides a multi-stage electric cylinder that employs an inward power transmission path and an inward-outward intersecting connection method, aiming to achieve a smaller radial dimension, a shorter transmission chain, and a simpler structural form. Combined with... Figures 1 to 3As shown, the multi-stage electric cylinder specifically includes a drive mechanism 2 and a telescopic assembly 3; the telescopic assembly 3 includes multiple lead screws and multiple lifting rods coaxially nested together; adjacent lead screws can slide relative to each other along the lead screw axis, and adjacent lifting rods can slide relative to each other along the lifting rod axis; the outermost lead screw is located inside the innermost lifting rod; the lead screws and lifting rods are connected by an inner and outer cross threaded engagement; the innermost lead screw and the outermost lifting rod are connected by a threaded pair transmission, and the outermost lead screw and the innermost lifting rod are connected by a threaded pair transmission, and each intermediate lead screw is connected to its corresponding lifting rod by a threaded pair transmission; the innermost lead screw is connected to the drive mechanism 2; when the drive mechanism 2 drives the innermost lead screw to rotate, the driving force output by the drive mechanism 2 is transmitted from the innermost lead screw through the successive lead screws to the outermost lead screw, and through the threaded pairs between each lead screw and its corresponding lifting rod, drives each lifting rod to achieve synchronous telescopic movement.

[0028] Combination Figure 1 As shown, the telescopic assembly 3 is a three-stage telescopic structure. The telescopic assembly 3 includes, from the inside out, a primary lead screw 31, a secondary lead screw 32, and a tertiary lead screw 33, and from the inside out, a primary lifting rod 34, a secondary lifting rod 35, and a tertiary lifting rod 36. The tertiary lead screw 33 is located inside the primary lifting rod 34. The primary lead screw 31 is connected to the drive mechanism 2. The tertiary lifting rod 36 engages with the primary lead screw 31 via a threaded pair, the primary lifting rod 34 engages with the tertiary lead screw 33 via a threaded pair, and the secondary lifting rod 35 engages with the secondary lead screw 32 via a threaded pair. The engagement relationship between the lead screws and lifting rods constitutes an inner and outer cross-threaded engagement, i.e., the primary lead screw 31 (innermost) engages with the tertiary lifting rod 36 (outermost), the tertiary lead screw 33 (outermost) engages with the primary lifting rod 34 (innermost), and the secondary lead screw 32 engages with the secondary lifting rod 35 (middle). Each lead screw is provided with an external thread, and each lifting rod is provided with a corresponding internal thread. The lower end of each lifting rod is provided with a vertically penetrating reduced diameter structure 37, and the inner wall of the reduced diameter structure is provided with an internal thread that mates with the external thread on each lead screw.

[0029] For example, when the telescopic assembly is a four-stage telescopic structure, it includes, from the inside out, a primary lead screw, a secondary lead screw, a tertiary lead screw, and a quaternary lead screw, as well as, from the inside out, a primary lifting rod, a secondary lifting rod, a tertiary lifting rod, and a quaternary lifting rod. In this case, the fit between the lead screws and the lifting rods is as follows: the primary lead screw (innermost) and the quaternary lifting rod (outermost) are fitted with a threaded pair; the secondary lead screw and the tertiary lifting rod are fitted with a threaded pair; the tertiary lead screw and the tertiary lifting rod are fitted with a threaded pair; and the quaternary lead screw (outermost) and the primary lifting rod (innermost) are fitted with a threaded pair.

[0030] Furthermore, each lead screw penetrates the bottom wall of the lifting rod that is threadedly engaged with it along its own axial direction; and except for the innermost lifting rod, the inner surface of the bottom wall of each of the other lifting rods abuts against the bottom end of the adjacent lead screw located outside the lead screw that is threadedly engaged with it. Figure 1 Taking the three-stage telescopic structure as an example, the innermost lead screw is the first-stage lead screw 31, the middle lead screw is the second-stage lead screw 32, and the outermost lead screw is the third-stage lead screw 33. The innermost lifting rod is the first-stage lifting rod 34, the middle lifting rod is the second-stage lifting rod 35, and the outermost lifting rod is the third-stage lifting rod 36. The inner surface of the bottom wall specifically refers to the annular surface located on the outer periphery of the upper opening of the diameter-reducing structure 37. The first-stage lead screw 31 penetrates the bottom wall of the third-stage lifting rod 36 along its own axial direction, and the inner surface of the bottom wall of the third-stage lifting rod 36 abuts against the bottom end of the second-stage lead screw 32; the second-stage lead screw 32 penetrates the bottom wall of the second-stage lifting rod 35 along its own axial direction, and the inner surface of the bottom wall of the second-stage lifting rod 35 abuts against the bottom end of the third-stage lead screw 33; the third-stage lead screw 33 penetrates the bottom wall of the first-stage lifting rod 34 along its own axial direction, and there is no lead screw abutting against the inner surface of the bottom wall of the first-stage lifting rod 34. Each lead screw drives its corresponding lifting rod to generate axial displacement through a threaded pair; when each lifting rod moves axially, it synchronously drives the lead screw that abuts it to generate axial displacement; the rotational drive of the lead screw and the axial drive of the lifting rod work together to realize the synchronous extension and retraction of each stage of the lifting rod. More specifically, in the cooperation relationship between the first-stage lead screw 31 and the third-stage lifting rod 36, the first-stage lead screw 31 (innermost) is driven to rotate by the drive mechanism 2, and drives the third-stage lifting rod 36 (outermost) to extend axially through the threaded pair; at the same time, the inner surface of the bottom wall of the third-stage lifting rod 36 abuts against the bottom end of the second-stage lead screw 32. When the third-stage lifting rod 36 is driven to extend by the first-stage lead screw 31, the second-stage lead screw 32 moves synchronously in the extension direction through this abutment relationship. Since the secondary lead screw 32 and the secondary lifting rod 35 are also connected by a threaded pair, the axial movement of the secondary lead screw 32 further drives the secondary lifting rod 35 to generate axial displacement. The inner surface of the bottom wall of the secondary lifting rod 35 abuts against the bottom end of the tertiary lead screw 33, thereby driving the tertiary lead screw 33 to move synchronously. The tertiary lead screw 33 then drives the primary lifting rod 34 to extend through the threaded pair. In this way, a cascade linkage is formed in which the lead screw rotates to drive the lifting rod and the lifting rod drives the lead screw axially, ultimately realizing the synchronous extension and retraction of each stage of the lifting rod.

[0031] In one specific embodiment, the lead screw and the lifting rod are coaxially arranged, and the number of lead screws and lifting rods is equal. A first connecting structure is provided between two adjacent lead screws; the first connecting structure is a spline connection structure; the first connecting structure is used to transmit circumferential torque between the lead screws and allow axial relative displacement between the lead screws. For example, in two adjacent lead screws, the outer wall of the inner lead screw is provided with an external spline, and the inner wall of the outer lead screw is provided with an internal spline, and the external spline and the internal spline mesh with each other. A second connecting structure is provided between two adjacent lifting rods; the second connecting structure is a spline connection structure; the second connecting structure is used to restrict the relative rotation between each lifting rod, while allowing axial relative sliding between each lifting rod. Through the above arrangement, the overall structure of the multi-stage electric cylinder is simple and has fewer parts. This invention realizes torque transmission and axial relative sliding between stages through spline connection, eliminating the additional parts such as intermediate nuts and bearing seats used to connect different stages of lead screws in traditional designs, reducing the number of parts, and lowering assembly difficulty and manufacturing costs.

[0032] In one specific embodiment, the multi-stage electric cylinder further includes a cylinder barrel 1 for accommodating the drive mechanism 2 and the telescopic assembly 3, and for guiding and constraining the telescopic assembly 3. The cylinder barrel 1 is fitted onto the outside of the outermost lifting rod. A guide structure is provided between the cylinder barrel 1 and the outermost lifting rod, which restricts the rotation of the outermost lifting rod relative to the cylinder barrel and allows the outermost lifting rod to slide along its own axial direction. The drive mechanism 2 is fixed to the lower end of the cylinder barrel 1, and the innermost lead screw is rotatably connected to the cylinder barrel 1 through a rotating bearing. The output shaft axis of the drive mechanism 2 is parallel to or coincides with the lead screw axis. The bottom end of the cylinder barrel 1 and the top end of the innermost lifting rod are both provided with a first connecting member 41 and a second connecting member 42 for connecting with external components.

[0033] In one specific embodiment, the drive mechanism 2 is a servo motor; the output shaft of the drive mechanism 2 transmits rotational motion to the innermost lead screw through a gear transmission pair to provide power output. Specifically, the rotational power output by the drive mechanism 2 first drives the innermost lead screw to rotate, and the innermost lead screw directly drives the outermost lifting rod to extend and retract axially through a threaded pair. At the same time, the innermost lead screw transmits rotational power to the adjacent inner second lead screw through torque transmission, and the inner second lead screw then drives the corresponding level of lifting rod to extend and retract axially through a threaded pair, and so on to achieve multi-level synchronous extension and retraction.

[0034] In one specific embodiment, except for the innermost lead screw, all other lead screws are hollow cylindrical structures; all lifting rods are also hollow cylindrical structures. The innermost lead screw is a solid rod structure, which directly bears the rotational torque input by the drive mechanism. The solid structure ensures sufficient torsional stiffness and strength, enabling stable transmission of power to the entire telescopic assembly.

[0035] In summary, this invention provides a multi-stage electric cylinder comprising a drive mechanism and a telescopic assembly. The telescopic assembly includes multiple lead screws and multiple lifting rods coaxially nested together. Adjacent lead screws can slide relative to each other along their axial direction, and adjacent lifting rods can slide relative to each other along their axial direction. The outermost lead screw is located inside the innermost lifting rod. The lead screws and lifting rods are connected by interlocking threads. The innermost lead screw and the outermost lifting rod are connected via a threaded pair, and the outermost lead screw and the innermost lifting rod are also connected via a threaded pair. Each intermediate lead screw is connected to its corresponding lifting rod via a threaded pair. The innermost lead screw is connected to the drive mechanism. When the drive mechanism drives the innermost lead screw to rotate, the driving force output by the drive mechanism is transmitted from the innermost lead screw to the outermost lead screw and drives each lifting rod to achieve synchronous telescopic movement through the threaded pairs between each lead screw and its corresponding lifting rod. The radial dimension is significantly reduced. This invention employs an inside-out power transmission path, with power input from the innermost lead screw and transmitted step-by-step outwards to drive the lifting rods at each level. Compared to the existing outside-in nested structure, the radial structure of this invention is more compact, and the radial dimension is significantly reduced, enabling a smaller installation diameter, making it particularly suitable for applications with extremely limited installation space. The direct inside-out transmission mode of this invention allows the rotational power of the drive mechanism to be transmitted step-by-step outwards only through the connection structure between each lead screw, significantly reducing intermediate transmission links and shortening the transmission chain. This reduces cumulative transmission errors and energy losses, thereby improving transmission efficiency and system response speed. This invention also eliminates the need for additional components such as intermediate nuts and bearing seats used to connect different levels of lead screws in traditional designs, reducing the number of parts, assembly difficulty, and manufacturing costs.

[0036] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A multi-stage electric cylinder, characterized in that, include: Drive mechanism and telescopic components; The telescopic assembly includes multiple lead screws and multiple lifting rods arranged coaxially and nested together. Two adjacent lead screws can slide relative to each other along the lead screw axis, and two adjacent lifting rods can slide relative to each other along the lifting rod axis; The outermost lead screw is located inside the innermost lifting rod; The lead screw and the lifting rod are connected by an inner and outer cross threaded engagement; the innermost lead screw and the outermost lifting rod are connected by a threaded pair, and the outermost lead screw and the innermost lifting rod are connected by a threaded pair. Each of the middle lead screws is connected to its corresponding lifting rod by a threaded pair. The innermost lead screw is connected to the drive mechanism for transmission; when the drive mechanism drives the innermost lead screw to rotate, the driving force output by the drive mechanism is transmitted from the innermost lead screw to the outermost lead screw and drives each lifting rod to achieve synchronous extension and retraction through the threaded pair between each lead screw and the corresponding lifting rod.

2. The multi-stage electric cylinder according to claim 1, characterized in that, Each lead screw passes through the bottom wall of the lifting rod that is threadedly engaged with it along its own axis; and except for the innermost lifting rod, the inner surface of the bottom wall of each of the other lifting rods also abuts against the bottom end of the adjacent lead screw located outside the lead screw that is threadedly engaged with the lifting rod.

3. The multi-stage electric cylinder according to claim 2, characterized in that, Each lead screw drives the corresponding lifting rod to generate axial displacement through a threaded pair; when each lifting rod moves axially, it synchronously drives the lead screw that abuts it to generate axial displacement; the rotation drive of the lead screw and the axial drive of the lifting rod work together to realize the synchronous extension and retraction movement of each level of lifting rod.

4. The multi-stage electric cylinder according to claim 1, characterized in that, The lead screw and the lifting rod are coaxially arranged, and the number of lead screws and lifting rods is equal.

5. The multi-stage electric cylinder according to claim 1, characterized in that, A first connecting structure is provided between two adjacent lead screws; the first connecting structure is a spline connection structure; the first connecting structure is used to transmit circumferential torque between the lead screws and allow axial relative displacement between the lead screws.

6. The multi-stage electric cylinder according to claim 1, characterized in that, A second connecting structure is provided between two adjacent lifting rods; the second connecting structure is a spline connection structure; the second connecting structure is used to restrict the relative rotation between each lifting rod, while allowing axial relative sliding between each lifting rod.

7. The multi-stage electric cylinder according to claim 1, characterized in that, The multi-stage electric cylinder also includes a cylinder barrel for accommodating the drive mechanism and telescopic components, the cylinder barrel being fitted over the outermost lifting rod; a guide structure is provided between the cylinder barrel and the outermost lifting rod, the guide structure being used to restrict the rotation of the outermost lifting rod relative to the cylinder barrel and to allow the outermost lifting rod to slide along its own axial direction.

8. The multi-stage electric cylinder according to claim 1, characterized in that, The drive mechanism is a servo motor; the output shaft of the drive mechanism transmits the rotational motion to the innermost lead screw through a gear transmission pair.

9. The multi-stage electric cylinder according to claim 1, characterized in that, The telescopic assembly is a three-stage telescopic structure; the telescopic assembly includes a first-stage lead screw, a second-stage lead screw and a third-stage lead screw arranged sequentially from the inside to the outside, and a first-stage lifting rod, a second-stage lifting rod and a third-stage lifting rod arranged sequentially from the inside to the outside. The third-stage lead screw is located inside the first-stage lifting rod; the first-stage lead screw is connected to the drive mechanism, the third-stage lifting rod is engaged with the first-stage lead screw through a threaded pair, the first-stage lifting rod is engaged with the third-stage lead screw through a threaded pair, and the second-stage lifting rod is engaged with the second-stage lead screw through a threaded pair.

10. The multi-stage electric cylinder according to claim 1, characterized in that, Except for the innermost lead screw, all other lead screws are hollow cylindrical structures; all the lifting rods are hollow cylindrical structures.

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