An electric stringer

Abstract

The utility model relates to electric power equipment technical field especially relates to a kind of electric tightener, including rack, reel, cable, power device, lifting hook and cable centering device, first roller and second roller of intermeshing are rotationally arranged on rack, cable is clamped between first roller and second roller, first drive wheel group is driven first roller and second roller synchronous rotation by second drive wheel group, the cable clamped between first roller and second roller is automatically conveyed out line outward;Tightener also has the function of anti-reverse when loosening, anti-collision when tightening, titanium alloy hook is used, lightweight design is carried out.

Description

Technical Field

[0001] This utility model relates to the field of power equipment technology, and in particular to an electric wire tensioner. Background Technology

[0002] An electric cable tensioner is a common tool used for tensioning cables. It typically has hooks at both ends; one end is used to hook the cable to be tensioned, and the other end is fixed to a support or anchor point. In the initial operation phase, the cable that was originally wound up needs to be extended outwards by a certain length so that the hooks at both ends can smoothly connect the cable to the anchor.

[0003] Currently, most common cable tensioning devices use a motor-driven reel to rotate, thus conveying the cable forward. To prevent uneven cable winding and tangled rope arrangement that could lead to cable compression, stacking, and deformation, a centering ring is often placed in the middle of the front of the reel. This ensures that the cable is neatly wound on the winch at the correct angle and position. Examples include the anti-twist ring in an electric fast cable tensioner (patent CN202111362640.3) and the rectangular centering seat in a cable tensioner for cable construction (patent 202411473218.9), which serve this purpose.

[0004] Because the cable on the reel and the centering ring often form an angle, and the cable itself has a certain degree of flexibility and malleability, they can sometimes overlap during the rapid release of the cable driven by the motor, leading to cable blockage. This not only affects normal delivery but also easily causes the cable to become kinked over time. In such cases, manual assistance is needed to pull the cable to overcome the blockage. However, this method is not only cumbersome but also increases the workload of the operators. Utility Model Content

[0005] To address the potential cable blockage and kinking issues that may occur between the reel and the centering ring in existing cable tensioners, this invention provides an electric cable tensioner that ensures smooth cable transport and saves manpower.

[0006] To achieve the above objectives, the following technical solution is provided: An electric cable tensioner includes a frame, a reel, a cable, a power unit, a hook, and a cable centering device. The power unit is connected to one end of the reel via a first drive wheel set. A first roller and a second roller are rotatably mounted on the frame and mesh with each other. The cable is clamped between the first roller and the second roller. The other end of the reel is connected to a second drive wheel set that drives the first roller to rotate. The first roller and the second roller clamp and pull the cable to move by friction.

[0007] Furthermore, the first drive wheel assembly includes a worm gear connected to the drive shaft of the power unit and a worm wheel meshing with the worm gear drive, the worm wheel being coaxially connected to the end of the reel.

[0008] Furthermore, the second drive wheel set includes a driven gear coaxially connected to the other end of the spool, and the driven gear is connected to the first roller drive through the first reduction wheel set.

[0009] Furthermore, it also includes a stroke measuring device, which includes a measuring gear, a measuring hole on the side wall of the measuring gear, and a measuring sensor that mates with the measuring hole on the outside of the measuring gear; the measuring gear is connected to the reel drive via a second reduction gear set.

[0010] Furthermore, the power unit includes a power supply, a motor, a gear shifting mechanism, an operating handle, and a coupling connected to the drive shaft; the motor and gear shifting mechanism are installed inside the operating handle, and a first sun gear is provided on the motor drive shaft. The gear shifting mechanism includes a first internal gear ring, a first planetary gear set, a first planetary carrier, a second internal gear ring, a second planetary gear set, a shift fork, and an adjustment switch that cooperates with the shift fork. The outer edge of the second internal gear ring is provided with an annular groove, and both sides of the shift fork are provided with connecting rods that extend into the annular groove; the first planetary gear set is rotatably mounted on the side of the gear disk near the motor, the first planetary carrier is provided with external teeth in the circumference, and a second sun gear is coaxially mounted on the other side of the first planetary carrier; the second planetary gear set is rotatably mounted on the second planetary carrier connected to the coupling, and the shift fork drives the second internal gear ring to cooperate with the second planetary gear set and the first planetary carrier respectively.

[0011] Furthermore, the free end of the cable is fixed to a mounting post inside the frame, and a tension sensor that works with the cable is provided on the outer side of the mounting post.

[0012] Furthermore, one end of the frame where the cable centering device is located is also equipped with an anti-collision lever that cooperates with the hook. The anti-collision lever is rotatably mounted inside the frame, and a baffle is provided at the bottom of the anti-collision lever. A photoelectric sensor that cooperates with the baffle is provided inside the frame.

[0013] The working principle of this utility model is as follows: the electric power provides power to drive the reel to rotate through the first drive wheel set. At the same time as the reel rotates, the second drive wheel set, which is connected to the reel drive, drives the first roller and the second roller to rotate, thereby driving the cable clamped between the first roller and the second roller to be transported outward, replacing manual traction.

[0014] The beneficial effects of this utility model are as follows: 1. The first drive wheel set drives the first roller and the second roller to rotate synchronously through the second drive wheel set, which automatically feeds the cable clamped between the first roller and the second roller outward without manual traction, ensuring smooth cable delivery and saving manpower; 2. The setting of the measuring gear and measuring sensor can not only detect the length of the tightened and loosened wire, but also prevent reverse rotation when the wire is loosened; by setting the anti-collision lever, it can prevent the hook from colliding with the frame or getting stuck in the frame when tightening the wire; 3. The winding limit bracket can prevent the front hook from damaging the equipment body when the wire is tightened to a certain extent; the hook is a titanium alloy hook with a lightweight design, the overall weight of the machine body is less than five kilograms, and the rated tensile force is 2T; 4. The power unit is equipped with two speed settings to improve operability and efficiency. In the initial stage of cable release or retraction under no-load conditions, the high speed can be used to quickly release or rewind the cable. In the stage where precise tension is required, the low speed can slowly tighten the cable, making it easy to accurately control the tension. Attached Figure Description

[0015] Appendix Figure 1 This is a structural diagram of the electric wire tensioner of this utility model; Appendix Figure 2 This is a perspective view of the electric wire tensioner of this utility model; Appendix Figure 3 This is a diagram showing the overall internal structure of the electric wire tensioner of this utility model; Appendix Figure 4 for Figure 3 Another structural diagram; Appendix Figure 5 This is an internal disassembly diagram of the electric wire tensioner of this utility model; Appendix Figure 6 This is another disassembly diagram of the internal structure of the electric wire tensioner of this utility model; Appendix Figure 7 This is an exploded view of the gear-adjusting structure in this utility model; Appendix Figure 8 This is an exploded perspective view of the gear-adjusting structure in this utility model; Appendix Figure 9 This is an exploded perspective view of the gear-adjusting structure in this utility model from another angle; Appendix Figure 10 for Figure 9 Enlarged view of a portion of the image; Appendix Figure 11 This is a structural diagram of the driven gear; Appendix Figure 12 This is a schematic diagram of the installation structure of the anti-collision lever; In the diagram: 1. Frame; 2. Reel; 3. Cable; 4. First hook; 5. Second hook; 6. First roller; 7. Second roller; 8. Worm; 9. Worm gear; 10. Housing; 11. Driven gear; 12. Measuring gear; 13. Measuring hole; 14. Measuring sensor; 15. Power supply; 16. Motor; 17. Operating handle; 18. Drive shaft; 19. Coupling; 20. First sun gear; 21. First internal gear ring; 22. First planetary gear set; 23. First planetary carrier. 24. Second internal gear ring; 25. Second planetary gear set; 26. Shift fork; 27. Adjustment switch; 28. Annular groove; 29. ​​Connecting rod; 30. Second sun gear; 31. Second planetary carrier; 32. Centering limit bracket; 33. Rewinding limit bracket; 34. Tension sensor; 35. Reduction gear one; 36. Reduction gear two; 37. Reduction gear three; 38. Slider; 39. Slot; 40. Limiting spring; 41. Anti-collision lever; 42. Baffle; 43. Photoelectric sensor. Detailed Implementation

[0016] The electric wire tensioner of this utility model will be further described below with reference to the embodiments.

[0017] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, an electric cable tensioner includes a frame 1, a reel 2, a cable 3, a power unit, a hook, and a cable centering device. The power unit is connected to one end of the reel 2 via a first drive wheel set. A first roller 6 and a second roller 7 are rotatably mounted on the frame 1 and mesh with each other. The cable 3 is clamped between the first roller 6 and the second roller 7. The other end of the reel 2 is connected to a second drive wheel set that drives the first roller 6 to rotate. The first roller 6 and the second roller 7 clamp and pull the cable 3 to move through friction.

[0018] Among them, such as Figure 3 , Figure 4 , Figure 5 As shown, the frame 1 is a frame structure. The two ends of the reel 2 are rotatably installed inside the frame 1 through bearings. The hook includes a first hook 4 and a second hook 5. The first hook 4 is installed at one end of the frame 1 through a connecting ear and is rotatably installed on the connecting ear. A pulley is installed on the second hook 5. One end of the cable 3 is wound around the reel 2, and the other end is wrapped around the pulley and fixed to the frame 1.

[0019] like Figure 3 , Figure 6As shown, the first drive wheel assembly includes a worm 8 connected to the drive shaft 18 of the power unit and a worm wheel 9 meshing with the worm 8. The worm wheel 9 is coaxially connected to the end of the winding reel 2. The power unit includes a power supply 15, a motor 16, and a coupling 19 connected to the drive shaft 18 of the motor 16; the worm 8 is connected to the coupling 19. The frame 1 is housed inside the housing 10. The bottom of the housing 10 is an operating handle 17. The power supply 15, the motor 16, and the coupling 19 are all located inside the operating handle 17. The power supply 15 is a battery, and the battery holder is plugged into the housing 10 and connected to the motor 16 through a circuit. The operating handle 17 is also equipped with a start / stop button to control the start and stop of the motor 16. When the motor 16 starts, it drives the worm 8 to rotate, which in turn drives the worm wheel 9 to rotate, thereby driving the winding reel 2 to rotate and wind or unwind the cable 3. The reel drives the first roller 6 and the second roller 7 to rotate synchronously via the second drive wheel set, conveying the cable clamped between the first roller 6 and the second roller 7 outwards, achieving automatic cable delivery without manual traction, ensuring smooth cable transport and saving manpower. In this embodiment, the first roller 6 and the second roller 7 are cylindrical, with the gap between them slightly smaller than the cable diameter to generate frictional driving force. The first hook 4 and the second hook 5 are both made of titanium alloy hooks, with an overall lightweight design, weighing less than five kilograms, and a rated tensile force of 2T, making them twice as fast as conventional hand-operated cable tensioners. In other embodiments, the first roller 6 and the second roller 7 are both provided with conical annular grooves in the middle of their cylindrical bodies to accommodate the cable entry angle, ensuring the cable is centered in the clamping position; the gap formed between the conical annular grooves is smaller than the cable diameter to clamp the cable securely.

[0020] like Figure 4 As shown, the second drive wheel assembly includes a driven gear 11 coaxially connected to the other end of the reel. The driven gear 11 is connected to the first roller 6 via a first reduction wheel assembly. Both the first roller 6 and the second roller 7 have meshing gear rings coaxially mounted on the same side. The first reduction wheel assembly includes a first reduction gear 35 and a second reduction gear 36, both located on the side of the frame 1. The first reduction gear 35 meshes with the driven gear 11 and the second reduction gear 36 respectively, while the second reduction gear 36 is fixed to an extension shaft at one end of the first roller 6. The first reduction wheel assembly adjusts the gear ratio to ensure that the speed at which the reel 2 releases the cable 3 is synchronized with the speed at which the first roller 6 and the second roller 7 release the cable 3, ensuring smooth release of the cable 3. A suitable gear ratio can be set by adjusting the rotational speed versus linear speed between the reel 2 and the rollers; this is a conventional method mastered by those skilled in the art and will not be described in detail here.

[0021] Better, such as Figure 4 , Figure 11As shown, the device also includes a stroke measuring device, which comprises a measuring gear 12. The measuring gear 12 has a measuring hole 13 on its side wall, and a measuring sensor 14 that mates with the measuring hole 13 is located on the outside of the measuring gear 12. The measuring gear 12 is connected to the reel via a second reduction gear set. The measuring gear 12 is mounted on the outside of the frame 1 via a rotating shaft. The second reduction gear set includes a reduction gear 37, which is coaxially fixed on the driven gear 11. The reel 2 drives the driven gear 11 to rotate, and the reduction gear 37 rotates synchronously with the driven gear 11, meshing with the measuring gear 12. The measuring sensor 14 is an infrared sensor, mounted on the frame using fasteners such as bolts or fixing rods. The infrared sensor includes a receiver and a transmitter, which are respectively positioned on opposite sides of the measuring gear 12. During the rotation of the measuring gear 12, the measuring light from the receiver passes through the measuring hole 13. When the measuring gear 12 rotates, the physical part of the gear blocks the infrared light emitted by the transmitter, while the measuring hole 13 allows light to pass through. The receiver then receives a series of "on-off" light pulse signals. The arrangement of the measuring gear 12 and the measuring sensor 14 not only detects the length of the tightened and loosened wires but also prevents reverse rotation during wire loosening (after the wire is unloaded, if the motor continues to drive, the reel will switch to the winding state). Specifically, when there is only one measuring hole 13, assuming the gear ratio of the reduction gear 37 to the measuring gear 12 is 8:160, when the reduction gear 37 rotates 15 times, the cable has been fully released or completely retracted. At this time, the measuring gear 12 has not yet rotated one revolution. Installing the measuring sensor 14 at the position corresponding to the measuring hole 13 at this time will complete the calibration of the motor 16 stop signal; the motor 16 stops upon receiving the signal from the measuring sensor 14. When there are multiple measuring holes 13, and the measuring holes 13 are evenly distributed along the edge of the measuring gear 12, the measuring sensor 14 can be flexibly positioned on the outer edge of the measuring gear 12. In this case, the specific number of pulse signals emitted when the cable has been fully released or completely retracted serves as the control signal for motor stop. For example, if the signal count is 9 when the cable is fully released, then the 9th signal is the motor stop signal. Additionally, the actual number of revolutions of the winding wheel 2 can be calculated based on the transmission ratio between the measuring gear 12 and the winding wheel 2, thereby obtaining the cable 3's release and retraction length. In this embodiment, the measuring gear 12 is located on the side of the frame 1 opposite to the worm gear 9 and the worm 8. In other embodiments, such as Figure 3 , Figure 5 As shown, it can also be set on the same side of the worm gear 9 and worm 8. The measuring sensor 14 can be, but is not limited to, a Lipu NE-670N slot-type photoelectric switch.

[0022] Better, such as Figure 4 , Figure 5As shown, a mounting post is fixed inside the frame 1. The cable centering device is a centering limit bracket 32 ​​located on the frame 1 on the side of the cable 3 outlet. The centering limit bracket 32 ​​is fixed to the top of the front opening of the frame 1 by bolts. The centering limit bracket 32 ​​has a slot in the middle, the width of which is slightly larger than the diameter of the cable 3. A winding limit bracket 33 is fixed to the bottom of the front opening of the frame 1 to prevent the pulley of the hook from getting stuck inside the frame 1 when the cable is tightened to a certain extent, thus preventing the front hook from damaging the equipment body. Figure 4 , Figure 12 As shown, an anti-collision lever 41 is provided between the centering limit frame 32 and the winding limit frame 33. The bottom of the anti-collision lever 41 is fixed inside the frame 1 by a pivot. A baffle 42 is provided at the bottom of the anti-collision lever 41, and a photoelectric sensor 43 is provided on the side of the baffle. In the initial state, the bottom of the anti-collision lever 41 can block the photoelectric sensor. During the winding process, when the pulley on the second hook 5 touches the anti-collision lever 41, it drives the anti-collision lever 41 to rotate backward. The baffle 42 also rotates with it. The photoelectric sensor 43 sends a sensing signal, triggering the motor to stop, thereby preventing the pulley of the hook from hitting the frame 1 and avoiding damage to the equipment body. In this embodiment, the photoelectric sensor 43 can be, but is not limited to, an MQ13-1000LTNS normally closed photoelectric sensor.

[0023] Preferably, a tension sensor 34, which works with the cable 3, is installed on the outer side of the mounting post. The tension sensor 34 is connected to the tensioner control circuit and is used to continuously monitor the tension of the cable 3. When the tension sensor detects that the tension is close to or reaches the threshold, the system can automatically alarm or cut off the power supply 15, effectively preventing cable 3 breakage, equipment damage, or even personal injury accidents caused by overload. The model of the tension sensor is, but is not limited to, the YSOTL-YL-30t metal cylinder tension sensor.

[0024] Better, such as Figure 7 , Figure 8 , Figure 9 , Figure 10As shown, the power unit also includes a gear shifting mechanism; the motor 16 and the gear shifting mechanism are installed in the operating handle 17. The motor 16 has a first sun gear 20 on its drive shaft. The gear shifting mechanism includes a first internal gear ring 21, a first planetary gear set 22, a first planetary carrier 23, a second internal gear ring 24, a second planetary gear set 25, a shift fork 26, and an adjustment switch 27 that cooperates with the shift fork 26. The outer edge of the second internal gear ring 24 has an annular groove 28. Both sides of the shift fork 26 have connecting rods 29 that extend into the annular groove 28. The first planetary gear set 22 is rotatably mounted on the side of the gear plate near the motor 16. The first planetary carrier 23 has external teeth circumferentially. The other side of the first planetary carrier 23 has a second sun gear 30 coaxially mounted. The second planetary gear set 25 is rotatably mounted on the second planetary carrier 31 connected to the coupling 19. The shift fork 26 drives the second internal gear ring 24 to cooperate with the second planetary gear set 25 and the first planetary carrier 23 respectively.

[0025] The first internal gear ring 21 is fixed to the housing at the end of the motor 16. The first planetary gear set 22 is rotatably mounted on one side of the first planetary carrier 23 via a rotating shaft, and all planet gears in the first planetary gear set 22 mesh with the first internal gear ring 21. The second planetary gear set 25 is rotatably mounted on the second planetary carrier 31 connected to the coupling 19 via a rotating shaft, and the second sun gear 30, rotatably mounted on the other side of the first planetary carrier 23, meshes with the planet gears in the second planetary gear set 25. The second internal gear ring 24 has a guide post on its outer side, and the inner wall of the operating handle 17 has guide ribs that cooperate with the guide post. The guide ribs are circumferentially arranged on the inner wall of the housing, and the ends of the guide ribs are wedge-shaped. When the guide post approaches the guide ribs and contacts the ends of the guide ribs, it can smoothly cut into the gap between the guide ribs. This allows the second internal gear ring 24 to move axially along the guide groove under the drive of the shift fork 26. The adjustment switch 27 is slidably mounted on the outside of the operating handle 17 housing via a slide groove and a snap-fit. Inside the operating handle 17, there is a slider 38 connected to the adjustment switch 27. The slider 38 is rotatably connected to the shift fork 26. Two slots 39 are provided on the side of the slider 38, and a limiting spring 40 is provided inside the operating handle 17. When the operator slides the adjustment switch 27, the slider 38 drives the shift fork 26 to move. The shift fork 26 drives the second internal gear ring 24. The gear is adjusted by adjusting the position of the second internal gear ring 24. At the same time, as the slider 38 moves, the protrusion on the limiting spring 40 engages with one of the slots 39, thereby positioning the slider 38 and locking the gear. When it is necessary to switch gears, the limiting spring 40 engages with the corresponding slot 39 of the other slider 38 to lock the current gear. For example, when the adjustment switch 27 is turned to the first position, the shift fork 26 drives the second internal gear ring 24 to move, so that the second internal gear ring 24 meshes with the second planetary gear set 25 and the first planetary carrier 23. At this time, the second internal gear ring 24, the second planetary gear set 25, and the first planetary carrier 23 form a whole and remain relatively stationary. The motor 16 drives the first sun gear 20 to rotate, and the first planetary gear set 22 rotates around the first sun gear 20 along the inner ring of the first internal gear ring 21. The guide post on the outer side of the second internal gear ring 24 disengages from the guide groove. In addition, the connecting rod 29 of the shift fork 26 can slide in the annular groove 28 on the outer side of the second internal gear ring 24, so the second internal gear ring 24 can rotate. The first planetary carrier 23, the second internal gear ring 24, and the second planetary gear set 25 rotate together along the axis of the motor 16. The second planetary gear set 25 drives the coupling 19 to rotate, and the coupling 19 drives the worm gear 8 to rotate, thereby driving the worm wheel 9 and the winding wheel 2 to rotate. When the adjustment switch 27 is turned to the second position, the shift fork 26 drives the second internal gear ring 24 to move in the opposite direction, so that the second internal gear ring 24 meshes with the second planetary gear set 25. At the same time, the guide post on the outer side of the second internal gear ring 24 cuts into the gap between the guide ribs, and the guide post on the outer side of the second internal gear ring 24 will be stuck by the guide ribs and cannot rotate.When motor 16 drives the first sun gear 20 to rotate, the first planetary gear set 22 rotates around the first sun gear 20 within the inner ring of the first internal gear ring 21. The first planetary gear set 22 drives the first planet carrier 23 to rotate. The second sun gear 30 drives the second planetary gear set 25 to rotate around the second sun gear 30 along the inner ring of the second internal gear ring 24. The second planetary gear set 25 drives the coupling 19 to rotate, and the coupling 19 drives the worm gear 8 to rotate, thereby driving the worm wheel 9 and the winding wheel 2 to rotate. Figure 9 , Figure 10 As shown, when the adjusting switch 27 moves towards the worm gear 8, it enters the second position. The shift fork 26 drives the second internal gear ring 24, making the second internal gear ring 24, the second planetary gear set 25, and the first planetary carrier 23 form a whole. Conversely, when the adjusting switch 27 moves in the opposite direction towards the worm gear 8, it enters the first position. The operating handle 17 is equipped with start / stop buttons and reel-in / unload buttons for convenient operation.

Claims

1. An electric wire tensioner, comprising a frame (1), a reel (2), a cable (3), a power unit, a hook, and a cable centering device, wherein the power unit is connected to one end of the reel (2) via a first drive wheel set, characterized in that, The frame (1) is rotatably equipped with a first roller (6) and a second roller (7) that mesh with each other. The cable (3) is clamped between the first roller (6) and the second roller (7). The other end of the reel (2) is connected to a second drive wheel group that drives the first roller (6) to rotate. The first roller (6) and the second roller (7) clamp and pull the cable (3) to move by friction.

2. The electric wire tensioner according to claim 1, characterized in that, The first drive wheel set includes a worm (8) connected to the drive shaft (18) of the power unit and a worm wheel (9) meshing with the worm (8). The worm wheel (9) is coaxially connected to the end of the reel (2).

3. The electric wire tensioner according to claim 2, characterized in that, The second drive wheel set includes a driven gear (11) coaxially connected to the other end of the spool. The driven gear (11) is connected to the first roller (6) via the first reduction wheel set.

4. The electric wire tensioner according to claim 2 or 3, characterized in that, It also includes a stroke measuring device, which includes a measuring gear (12), a measuring hole (13) on the side wall of the measuring gear (12), and a measuring sensor (14) that cooperates with the measuring hole (13) on the outside of the measuring gear (12); the measuring gear (12) is connected to the reel drive through the second reduction gear set.

5. The electric wire tensioner according to any one of claims 1 to 3, characterized in that, The power unit includes a power source (15), a motor (16), a gear shifting mechanism, an operating handle (17), and a coupling (19) connected to the drive shaft (18). The motor (16) and the gear shifting mechanism are installed inside the operating handle (17). The motor (16) has a first sun gear (20) on its drive shaft. The gear shifting mechanism includes a first internal gear ring (21), a first planetary gear set (22), a first planetary carrier (23), a second internal gear ring (24), a second planetary gear set (25), a shift fork (26), and an adjustment switch (27) that cooperates with the shift fork (26). (24) An annular groove (28) is provided on the outer edge, and connecting rods (29) extending into the annular groove (28) are provided on both sides of the shift fork (26); the first planetary gear set (22) is rotatably set on the side of the gear plate close to the motor (16), the first planetary carrier (23) is provided with external teeth in the circumference, the second sun gear (30) is coaxially set on the other side of the first planetary carrier (23), the second planetary gear set (25) is rotatably set on the second planetary carrier (31) connected to the coupling (19), and the adjusting switch (27) drives the second internal gear ring (24) to move axially through the shift fork (26).

6. The electric wire tensioner according to claim 4, characterized in that, The power unit includes a power source (15), a motor (16), a gear shifting mechanism, an operating handle (17), and a coupling (19) connected to the drive shaft (18). The motor (16) and the gear shifting mechanism are installed inside the operating handle (17). The motor (16) has a first sun gear (20) on its drive shaft. The gear shifting mechanism includes a first internal gear ring (21), a first planetary gear set (22), a first planetary carrier (23), a second internal gear ring (24), a second planetary gear set (25), a shift fork (26), and an adjustment switch (27) that cooperates with the shift fork (26). (24) An annular groove (28) is provided on the outer edge, and connecting rods (29) extending into the annular groove (28) are provided on both sides of the shift fork (26); the first planetary gear set (22) is rotatably set on the side of the gear plate close to the motor (16), the first planetary carrier (23) is provided with external teeth in the circumference, the second sun gear (30) is coaxially set on the other side of the first planetary carrier (23), the second planetary gear set (25) is rotatably set on the second planetary carrier (31) connected to the coupling (19), and the adjusting switch (27) drives the second internal gear ring (24) to move axially through the shift fork (26).

7. The electric wire tensioner according to claim 1, 2, 3 or 6, characterized in that, The free end of the cable (3) is fixed on the mounting post inside the frame (1), and a tension sensor (34) that cooperates with the cable (3) is provided on the outside of the mounting post.

8. The electric wire tensioner according to claim 4, characterized in that, The free end of the cable (3) is fixed on the mounting post inside the frame (1), and a tension sensor (34) that cooperates with the cable (3) is provided on the outside of the mounting post.

9. The electric wire tensioner according to claim 5, characterized in that, The free end of the cable (3) is fixed on the mounting post inside the frame (1), and a tension sensor (34) that cooperates with the cable (3) is provided on the outside of the mounting post.

10. The electric wire tensioner according to claim 1, 2, 3, 6, 8 or 9, characterized in that, The frame (1) where the cable centering device is located is also provided with an anti-collision lever (41) that cooperates with the hook. The anti-collision lever (41) is rotatably set in the frame (1). A baffle (42) is provided at the bottom of the anti-collision lever (41). A photoelectric sensor (43) that cooperates with the baffle (42) is provided in the frame (1).

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