Vertical pipeline expansion device
By combining the design of electric winches and pulley assemblies, the problem of poor synchronization during the lifting of vertical pipes was solved, achieving synchronous lifting and force balance of the inner pipe, avoiding pipe tilting and jamming, and improving production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2026-03-06
AI Technical Summary
Conventional vertical pipe telescopic mechanisms suffer from poor synchronization between the left and right chain hoists, which can easily cause the pipe to tilt and jam during the lifting process, affecting production efficiency.
By employing an electric winch, wire rope, fixed pulley, and movable pulley assembly, and through the design of fixed points for the inner and outer tubes, the vertical rise or fall of the inner tube is achieved, ensuring synchronization and force balance.
This enabled the synchronous lifting of the inner pipe, avoiding pipe tilting and jamming, and improving production efficiency.
Smart Images
Figure CN223973432U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of pneumatic ship unloader technology, specifically to a vertical pipe telescopic device. Background Technology
[0002] Pneumatic conveying pipelines refer to complete sets of devices that use high-energy airflow to propel the transfer of bulk materials, and are commonly used components of pneumatic ship unloaders. Pneumatic conveying pipelines are generally divided into two types according to the conveying direction: horizontal pipelines and vertical pipelines. Among them, vertical pipelines perform vertical extension and retraction movements to control the suction nozzles to reach the top of the material and the bottom of the hatches for cleaning.
[0003] Conventional vertical pipe expansion joints consist of two sets of chain hoists arranged symmetrically on the left and right sides. The synchronous operation of these two sets of chain hoists achieves the purpose of expanding and contracting the pipe. However, because each chain hoist uses an independent brake, their opening time cannot be guaranteed to be synchronized. Furthermore, after long-term operation, inconsistent pulling forces between the left and right sides can easily occur, leading to problems such as pipe tilting and jamming, and even affecting the overall production efficiency of the machine. Therefore, ensuring that the vertical pipe is subjected to vertical force during the lifting process has become a pressing problem that needs to be solved. Utility Model Content
[0004] The technical problem to be solved by this utility model is to provide a vertical pipe expansion device. Through the cooperation of an electric winch, wire rope I, fixed pulley III, movable pulley II, and the outer pipe fixing point, the movable pulley I can be driven to move vertically up and down. Then, through the cooperation of the movable pulley I, wire rope II, fixed pulley I, fixed pulley II, and the two inner pipe fixing points, the vertical rise or fall of the inner pipe can be realized.
[0005] To solve the above-mentioned technical problems, this utility model adopts the following technical solution: The innovation of this utility model is as follows: it includes an outer pipe, an electric winch, a steel wire rope I, a fixed pulley III, a movable pulley assembly, an outer pipe fixing point, an inner pipe, a steel wire rope II, fixed pulley I, fixed pulley II, and an inner pipe fixing point; the inner pipe is coaxially sleeved inside the vertically arranged outer pipe, and its lower end extends vertically downward beyond the lower end face of the outer pipe, and is vertically and slidably connected to the outer pipe; the electric winch is located at the upper end of the front face of the outer circumference of the outer pipe, and the fixed pulley III is vertically and horizontally located at the lower end of the front face of the outer circumference of the outer pipe; the inner pipe extends outward from the outer pipe... The outer circumference of the tube is symmetrically provided with inner tube fixing points on both the left and right sides. Furthermore, fixed pulleys II and I are symmetrically provided at intervals on the outer circumference of the outer tube relative to the electric winch. An outer tube fixing point is located on the outer circumference of the outer tube near fixed pulley III. The wire rope I is wound around the drum of the electric winch, with one end turning downwards via fixed pulley III, then turning upwards again via the lower end of the movable pulley assembly, and finally connecting to the outer tube fixing point. One end of the wire rope II is connected to the inner tube fixing point on the left side, and the other end turns upwards via fixed pulley II, then downwards again via the upper end of the movable pulley assembly, then downwards again via fixed pulley I, and finally connects to the outer tube fixing point on the right side.
[0006] Preferably, the drum portion of the electric winch is arranged horizontally and laterally, and does not interfere with the turning action of the wire rope II via the fixed pulley I and the fixed pulley II, and it must be ensured that the outer tube does not interfere with the winding and unwinding action of the wire rope I on the drum.
[0007] Preferably, it also includes a fixed pulley bracket III; the fixed pulleys III are spaced apart and positioned directly below the drum portion of the electric winch, and are mounted on the lower end of the outer circumference of the outer tube via the fixed pulley bracket III, ensuring that both the left and right end faces of the fixed pulleys III extend beyond the left and right sides of the fixed pulley bracket III; the fixed pulleys III and the fixed pulley bracket III are rotatably connected around their own axial direction, and one end of the wire rope I on the drum turns downward from the right side through the fixed pulley III and upward, ensuring that the outer tube, the movable pulley assembly, and the fixed pulley bracket III do not interfere with the turning action of the wire rope I through the fixed pulley III.
[0008] Preferably, the movable pulley assembly moves vertically up and down within the range between the electric winch and the fixed pulley III, and includes a movable pulley I, a movable pulley II, and a movable pulley support. The movable pulley support is vertically and horizontally positioned on the front side of the outer tube relative to the electric winch and the fixed pulley III, with a movable pulley I vertically and horizontally rotatably mounted at its upper end and a movable pulley II vertically and horizontally rotatably mounted at its lower end. The left and right end faces of both the movable pulley I and the movable pulley II extend beyond the left and right sides of the movable pulley support. The wire rope I, which turns upward via the fixed pulley III, turns downward via the movable pulley II from the left side and is then connected to the fixed point of the outer tube, ensuring that the movable pulley support does not interfere with the turning action of the wire rope I via the movable pulley II. The wire rope II, which turns downward via the fixed pulley II, turns upward via the movable pulley I from the left side, ensuring that the movable pulley support does not interfere with the turning action of the wire rope II via the movable pulley I.
[0009] Preferably, it also includes a fixed pulley bracket I; the fixed pulley I is vertically arranged in a quarter-sector area between the right end of the electric winch and the fixed point of the inner tube on the right side, and it is installed on the outer circumference of the outer tube through the fixed pulley bracket I at the corresponding position, ensuring that the left and right end faces of the fixed pulley I extend out of the left and right sides of the fixed pulley bracket I; the fixed pulley I and the fixed pulley bracket I are rotatably connected around their own axis, and their rotation direction is tangential to the outer tube, so that the wire rope II, which turns upward through the upper end of the movable pulley assembly, turns downward from the left side through the fixed pulley I, and ensures that neither the outer tube nor the fixed pulley bracket I interferes with the turning action of the wire rope II through the fixed pulley I.
[0010] Preferably, it also includes a fixed pulley bracket II; the fixed pulley II is vertically arranged in a quarter-sector area between the left end of the electric winch and the fixed point of the left inner tube, and it is installed on the corresponding position on the outer circumference of the outer tube through the fixed pulley bracket II, ensuring that the left and right end faces of the fixed pulley II extend out of the left and right sides of the fixed pulley bracket II; the fixed pulley II and the fixed pulley bracket II are rotatably connected around their own axis, and their rotation direction is tangential to the outer tube, ensuring that the included angle between the fixed pulley I and the fixed pulley II is 90°, thereby causing the other end of the wire rope II to turn downward from the left through the fixed pulley II, and ensuring that neither the outer tube nor the fixed pulley bracket II interferes with the turning action of the wire rope II through the fixed pulley II.
[0011] Preferably, the outer tube fixing point is located at the upper right position near the fixed pulley bracket III, and does not interfere with the turning action of the wire rope I through the fixed pulley III, nor with the vertical up-and-down movement of the movable pulley assembly.
[0012] Preferably, an upper limit switch is provided on the outer circumferential surface of the outer tube near the electric winch directly below it, and a lower limit switch is provided on the outer circumferential surface near the fixed pulley bracket III directly above it, ensuring that neither the upper nor lower limit switch interferes with the turning motion of wire rope I and wire rope II; the upper and lower limit switches are both set within the vertical up-down movement trajectory of the movable pulley assembly, and the upper limit switch engages with the upper surface of the movable pulley bracket to limit the movable pulley assembly, and the lower limit switch engages with the lower surface of the movable pulley bracket to limit the movable pulley assembly.
[0013] The beneficial effects of this utility model are:
[0014] (1) This utility model can drive the movable pulley I to move vertically up and down by the cooperation of an electric winch, wire rope I, fixed pulley III, movable pulley II, and the fixed point of the outer tube. Then, by the cooperation of the movable pulley I, wire rope II, fixed pulley I, fixed pulley II, and the two fixed points of the inner tube, the vertical rise or fall of the inner tube can be realized.
[0015] (2) This utility model sets two inner tube fixing points on both sides of the inner tube and then pulls them through the same steel wire rope II, so that they can be completely synchronized, ensuring that the lifting speed on the left and right sides is consistent and the force is balanced, thus avoiding the phenomenon of pipe tilting during the traction process. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of the structure of a vertical pipe expansion joint of the present invention.
[0018] Figure 2 for Figure 1 Enlarged schematic diagram of the connection between the central moving pulley I and the outer tube.
[0019] Figure 3 for Figure 1 Enlarged schematic diagram of the connection between the moving pulley II and the inner tube.
[0020] Figure 4 This is a schematic diagram of the structure of the movable pulley I, movable pulley II, and movable pulley support of this utility model.
[0021] Figure 5 This is a schematic diagram of the winding of wire rope I and wire rope II of this utility model.
[0022] Among them, 1-fixed pulley I; 2-fixed pulley II; 3-wire rope I; 4-wire rope II; 5-moving pulley I; 6-moving pulley II; 7-fixed pulley III; 8-inner tube fixing point; 9-outer tube fixing point; 10-electric winch; 11-outer tube; 12-inner tube; 13-moving pulley bracket. Detailed Implementation
[0023] The technical solution of this utility model will be clearly and completely described below through specific embodiments.
[0024] This utility model discloses a vertical pipe expansion joint, comprising an outer pipe 11, an electric winch 10, a steel wire rope I3, a fixed pulley III7, a movable pulley assembly, an outer pipe fixing point 9, an inner pipe 12, a steel wire rope II4, fixed pulley I1, fixed pulley II2, and an inner pipe fixing point 8; the specific structure is as follows. Figures 1-5 As shown, the inner tube 12 is coaxially sleeved inside the vertically arranged outer tube 11, and its lower end extends vertically downward out of the lower end face of the outer tube 11 and slides vertically up and down with the outer tube 11; the electric winch 10 is located on the upper side of the outer circumference of the outer tube 11, and the drum part of the electric winch 10 is horizontally arranged. The electric winch 10 does not interfere with the turning action of the wire rope II4 through the fixed pulley I1 and the fixed pulley II2, and it is necessary to ensure that the outer tube 11 does not interfere with the winding and unwinding action of the wire rope I3 on the drum.
[0025] In this utility model, the fixed pulley Ⅲ7 is vertically and horizontally positioned at the lower end of the front side of the outer circumference of the outer tube 11; for example... Figures 1-5 As shown, on the outer circumference of the inner tube 12 extending into the outer tube 11, there are symmetrical inner tube fixing points 8 on both the left and right sides. On the outer circumference of the outer tube 11, relative to the electric winch 10, there are symmetrical fixed pulleys II2 and I1 spaced apart on the left and right sides. On the outer circumference of the outer tube 11, near the fixed pulley III7, there is an outer tube fixing point 9. The wire rope I3 is wound around the drum of the electric winch 10. One end of the wire rope goes downward, turns upward through the fixed pulley III7, then turns downward through the lower end of the movable pulley assembly, and is connected to the outer tube fixing point 9. One end of the wire rope II4 is connected to the inner tube fixing point 8 on the left side. The other end of the wire rope goes upward through the fixed pulley II2, then turns upward through the upper end of the movable pulley assembly, then turns downward through the fixed pulley I1, and is connected to the outer tube fixing point 9 on the right side.
[0026] like Figures 1-5As shown, fixed pulleys Ⅲ7 are spaced apart and positioned directly below the drum portion of the electric winch 10. They are mounted on the lower end of the outer circumference of the outer tube 11 via fixed pulley brackets Ⅲ, ensuring that both the left and right end faces of fixed pulleys Ⅲ7 extend beyond the left and right sides of fixed pulley brackets Ⅲ. Fixed pulleys Ⅲ7 and fixed pulley brackets Ⅲ are rotatably connected around their own axial direction. One end of the wire rope Ⅰ3 on the drum turns downward from the right side through fixed pulleys Ⅲ7 and upward, ensuring that the outer tube 11, the movable pulley assembly, and fixed pulley brackets Ⅲ do not interfere with the turning motion of the wire rope Ⅰ3 through fixed pulleys Ⅲ7.
[0027] This utility model's movable pulley assembly allows for vertical up-and-down movement within the range between the electric winch 10 and the fixed pulley III 7, and includes movable pulley I 5, movable pulley II 6, and movable pulley support 13; as Figures 1-5 As shown, the movable pulley bracket 13 is vertically and horizontally positioned on the front side of the outer tube 11, relative to the electric winch 10 and the fixed pulley Ⅲ7. A movable pulley Ⅰ5 is vertically and horizontally rotatably mounted on its upper end, and a movable pulley Ⅱ6 is vertically and horizontally rotatably mounted on its lower end. The left and right end faces of both movable pulley Ⅰ5 and movable pulley Ⅱ6 extend out from the left and right sides of the movable pulley bracket 13. The wire rope Ⅰ3, which is turned upwards via the fixed pulley Ⅲ7, turns downwards from the left side via the movable pulley Ⅱ6 and is then connected to the fixed point 9 on the outer tube, ensuring that the movable pulley bracket 13 does not interfere with the turning action of the wire rope Ⅰ3 via the movable pulley Ⅱ6. Similarly, the wire rope Ⅱ4, which turns downwards via the fixed pulley Ⅱ2, turns upwards from the left side via the movable pulley Ⅰ5, ensuring that the movable pulley bracket 13 does not interfere with the turning action of the wire rope Ⅱ4 via the movable pulley Ⅰ5.
[0028] like Figures 1-5 As shown, the fixed pulley I1 is vertically positioned within a quarter-sector area between the right end of the electric winch 10 and the right-side inner tube fixing point 8. It is mounted on the outer circumference of the outer tube 11 via a fixed pulley bracket I, ensuring that both the left and right end faces of the fixed pulley I1 extend beyond the left and right sides of the fixed pulley bracket I. The fixed pulley I1 and the fixed pulley bracket I are rotatably connected around their own axis, and their rotation direction is tangential to the outer tube 11. In this invention, the steel wire rope II4, which turns upwards via the upper end of the movable pulley assembly, turns downwards from the left side via the fixed pulley I1, ensuring that neither the outer tube 11 nor the fixed pulley bracket I interferes with the turning motion of the steel wire rope II4 via the fixed pulley I1.
[0029] like Figures 1-5As shown, the fixed pulley II2 is vertically positioned within a quarter-sector area between the left end of the electric winch 10 and the fixed point 8 on the left side of the inner tube. It is mounted on the outer circumference of the outer tube 11 via a fixed pulley bracket II, ensuring that both the left and right end faces of the fixed pulley II2 extend beyond the left and right sides of the fixed pulley bracket II. The fixed pulley II2 and the fixed pulley bracket II are rotatably connected around their own axis, with their rotation direction tangential to the outer tube 11, ensuring that the angle between the fixed pulley I1 and the fixed pulley II2 is 90°. The other end of the wire rope II4 of this invention rotates upwards from the left side via the fixed pulley II2 and downwards, ensuring that neither the outer tube 11 nor the fixed pulley bracket II interferes with the rotational movement of the wire rope II4 via the fixed pulley II2.
[0030] like Figures 1-5 As shown, the outer tube fixing point 9 is located at the upper right position near the fixed pulley bracket Ⅲ, and does not interfere with the turning action of the wire rope Ⅰ3 through the fixed pulley Ⅲ7, nor with the vertical up-and-down movement of the movable pulley assembly.
[0031] like Figures 1-5 As shown, an upper limit switch is provided on the outer circumference of the outer tube 11 near the electric winch 10 directly below it, and a lower limit switch is provided on the outer circumference of the outer tube 11 near the fixed pulley bracket III directly above it, ensuring that the upper limit switch and the lower limit switch do not interfere with the turning motion of the wire rope I3 and the wire rope II4; the upper limit switch and the lower limit switch are both set within the vertical up and down movement trajectory of the movable pulley assembly, and the upper limit switch is used to limit the movable pulley assembly by cooperating with the upper surface of the movable pulley bracket 13, and the lower limit switch is used to limit the movable pulley assembly by cooperating with the lower surface of the movable pulley bracket 13.
[0032] The working principle of this utility model:
[0033] (1) When the inner tube 12 needs to be lifted
[0034] The electric winch 10 operates and provides traction to wind up the wire rope I3. At this time, the wire rope I3 is redirected by the fixed pulley III7 to provide downward tension to the movable pulleys I5 and II6, and drives the movable pulleys I5 and II6 to descend vertically in sync. The tension is transmitted to the wire rope II4 and then redirected by the fixed pulleys I1 and II2 respectively, and finally transmitted to the two inner tube fixing points 8, thereby lifting the inner tube 12.
[0035] (2) When the inner tube 12 needs to be lowered
[0036] When the electric winch 10 is not working, the inner tube 12 descends vertically under its own weight. After the wire rope II4 is redirected by the fixed pulleys I1 and II2, it provides an upward pulling force to the movable pulley I5, and drives the movable pulleys I5 and II6 to rise vertically in sync. The pulling force is transmitted to the wire rope I3 and then redirected by the fixed pulley III7, thereby realizing the unwinding of the wire rope I3 on the electric winch 10.
[0037] The beneficial effects of this utility model are:
[0038] (1) This utility model can drive the movable pulley I5 to move vertically up and down through the cooperation of electric winch 10, wire rope I3, fixed pulley III7, movable pulley II6, and outer tube fixing point 9. Then, through the cooperation of movable pulley I5, wire rope II4, fixed pulley I1, fixed pulley II2, and two inner tube fixing points 8, the inner tube 12 can be vertically raised or lowered.
[0039] (2) This utility model sets two inner tube fixing points 8 on both sides of the inner tube 12 and then pulls them through the same steel wire rope II4, so that they can be completely synchronized, ensuring that the lifting speed on the left and right sides is consistent and the force is balanced, thus avoiding the phenomenon of pipe tilting during the traction process.
[0040] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the concept and scope of the present utility model. Without departing from the design concept of the present utility model, all modifications and improvements made by those skilled in the art to the technical solutions of the present utility model should fall within the protection scope of the present utility model. The technical content for which protection is sought in the present utility model has been fully recorded in the technical requirements.
Claims
1. A vertical pipe retraction apparatus, characterized by: The utility model provides a kind of lifting device, including outer tube, electric winch, steel wire rope I, fixed pulley III, movable pulley assembly, outer tube fixed point, inner tube, steel wire rope II, fixed pulley I, fixed pulley II and inner tube fixed point;The inner tube coaxial sleeve is connected inside the outer tube being arranged vertically, and its lower end vertically extends the lower end surface of the outer tube, and is vertically connected with the outer tube up and down sliding;The electric winch is arranged in the outer circumferential surface front side upper end position of the outer tube, and the fixed pulley III is vertically transversely arranged in the outer circumferential surface front side lower end position of the outer tube;Inner tube fixed point is also symmetrically provided on the part of the outer tube that the inner tube extends from the outer circumferential surface left and right sides, and fixed pulley II and fixed pulley I are also symmetrically provided on the outer circumferential surface of the outer tube relative to the electric winch upper left and right, and outer tube fixed point is provided on the outer circumferential surface of the outer tube relative to fixed pulley III position;The steel wire rope I is wound on the drum of electric winch, and its one end is downward to the fixed pulley III and is turned to upward, and then is connected to the outer tube fixed point after being turned to downward by the lower end of movable pulley assembly;The one end of the steel wire rope II is connected to the left inner tube fixed point, and its other end is turned to downward after being turned to upward by the fixed pulley II, and then is connected to the right outer tube fixed point after being turned to upward by the upper end of movable pulley assembly and being turned to downward by the fixed pulley I.
2. A vertical pipe retractor according to claim 1, wherein: The drum part of the electric winch is horizontally transversely arranged, and does not interfere with the turning action of the steel wire rope II through the fixed pulley I and the fixed pulley II, and needs to ensure that the outer tube does not interfere with the winding and unwinding action of the steel wire rope I on the drum.
3. A vertical pipe retractor according to claim 2, wherein: It also includes fixed pulley support III;The fixed pulley III is arranged in the position below the drum part of the electric winch, and is installed on the outer circumferential surface front side lower end position of the outer tube through the fixed pulley support III, and ensures that the left and right end surfaces of the fixed pulley III extend out of the left and right side surfaces of the fixed pulley support III;The fixed pulley III is connected to the fixed pulley support III through the rotation of its own axis, and one end of the steel wire rope I on the drum is turned to upward from the right side through the fixed pulley III, and ensures that the outer tube, movable pulley assembly and fixed pulley support III do not interfere with the turning action of the steel wire rope I through the fixed pulley III.
4. A vertical pipe retractor according to claim 3, wherein: The movable pulley assembly moves vertically up and down within the range between the electric winch and the fixed pulley III, and includes movable pulley I, movable pulley II and movable pulley support;The movable pulley support is vertically transversely arranged in the position between the electric winch and the fixed pulley III on the front side of the outer tube, and the movable pulley I is rotatably arranged on the upper end of the movable pulley support, and the movable pulley II is rotatably arranged on the lower end of the movable pulley support;The left and right end surfaces of the movable pulley I and the movable pulley II extend out of the left and right side surfaces of the movable pulley support, and the steel wire rope I turned to upward through the fixed pulley III is turned to downward from the left side through the movable pulley II, and then is connected to the outer tube fixed point, and ensures that the movable pulley support does not interfere with the turning action of the steel wire rope I through the movable pulley II; The steel wire rope II turned to downward through the fixed pulley II is turned to upward from the left side through the movable pulley I, and ensures that the movable pulley support does not interfere with the turning action of the steel wire rope II through the movable pulley I.
5. A vertical pipe retractor according to claim 4, wherein: Still include fixed pulley bracket I; The fixed pulley I is vertically arranged in the quarter sector area between the right end of the electric winch and the right side inner tube fixed point, and it is installed on the corresponding position of the outer circumference of the outer tube through the fixed pulley bracket I, and ensures that the left and right end faces of the fixed pulley I extend out of the left and right sides of the fixed pulley bracket I; The fixed pulley I is connected with the fixed pulley bracket I around its own axis to rotate, and its rotating direction is tangent to the outer tube, so that the steel wire rope II from the left side through the fixed pulley I is turned downward, and it is ensured that the outer tube and the fixed pulley bracket I do not interfere with the turning action of the steel wire rope II through the fixed pulley I.
6. A vertical pipe retractor according to claim 5, wherein: Still include fixed pulley bracket II; The fixed pulley II is vertically arranged in the quarter sector area between the left end of the electric winch and the left side inner tube fixed point, and it is installed on the corresponding position of the outer circumference of the outer tube through the fixed pulley bracket II, and ensures that the left and right end faces of the fixed pulley II extend out of the left and right sides of the fixed pulley bracket II; The fixed pulley II is connected with the fixed pulley bracket II around its own axis to rotate, and its rotating direction is tangent to the outer tube, and ensures that the included angle between the fixed pulley I and the fixed pulley II is 90°, so that the other end of the steel wire rope II is turned downward from the left side through the fixed pulley II, and it is ensured that the outer tube and the fixed pulley bracket II do not interfere with the turning action of the steel wire rope II through the fixed pulley II.
7. A vertical pipe telescoping device as defined in claim 3, wherein: The outer tube fixed point is arranged at the right upper position close to the fixed pulley bracket III, and does not interfere with the turning action of the steel wire rope I through the fixed pulley III, and does not interfere with the vertical up and down movement of the movable pulley assembly.
8. A vertical pipe telescoping device as defined in claim 3, wherein: An upper limit switch is further arranged on the outer circumference of the outer tube close to the position directly below the electric winch, and a lower limit switch is further arranged on the outer circumference close to the position directly above the fixed pulley bracket III, and it is ensured that the upper limit switch and the lower limit switch do not interfere with the turning action of the steel wire rope I and the steel wire rope II; The upper limit switch and the lower limit switch are arranged in the vertical up and down movement track of the movable pulley assembly, and the movable pulley assembly is upper limited through the cooperation of the upper limit switch and the upper surface of the movable pulley bracket, and is lower limited through the cooperation of the lower limit switch and the lower surface of the movable pulley bracket.