Traction device and elevator

Abstract

The utility model provides a traction device and an elevator. The traction device comprises a mounting frame which comprises a main body part and a supporting part, and the supporting part is arranged on the main body part in a protruding mode; the bearing shaft is arranged on the supporting part; the multiple traction motors are sequentially arranged on the bearing shaft in a sleeving mode in the axial direction of the bearing shaft; and the multiple traction wheels are fixedly arranged on the multiple traction motors in a sleeving mode, and the multiple traction motors are arranged to drive the multiple traction wheels to rotate. According to the traction device, the functions of the traction motor with the extra-large rated load capacity and the extra-large rated power are achieved through the multiple traction motors with the rated load capacity and the rated power, and the traction device can be applied to an extra-large freight elevator to replace the traction motor with the extra-large rated load capacity and the extra-large rated power; and the device has the advantages of stable operation, easiness in disassembly and maintenance, low difficulty in steel wire rope arrangement, easiness in starting and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of elevator equipment, and more specifically, to a traction device and an elevator. Background Art

[0002] Existing ordinary freight elevators use a permanent magnet synchronous traction machine (this traction machine includes a permanent magnet synchronous traction motor and a traction sheave fixedly mounted on the traction motor. The traction motor includes a load-bearing shaft, a stator fixedly mounted on the load-bearing shaft, and an outer rotor rotatably mounted on the stator) to drive the cargo box up and down. The maximum rated load of this traction machine is 60 tons and the maximum rated power is 200KW. For extra-large freight elevators, a traction machine with a larger rated load and higher rated power is required. However, for extra-large freight elevators with a rated load of no less than 100 tons, the following problems exist:

[0003] 1. Due to the significant increase in the size of the cargo box, the length and weight of the outer rotor in the traction machine axis will also increase significantly. This will cause the outer rotor to rotate unstable. In addition, after the traction machine fails, it will be difficult to disassemble and assemble due to the heavy weight of each component.

[0004] 2. Due to the significant increase in the size of the cargo box, the axial length of the traction sheave in the traction machine has been greatly increased, which will greatly increase the difficulty of arranging the wire rope;

[0005] 3. Due to the significant increase in the axial length of the outer rotor in the traction machine, the distance between the two bearings between the two ends of the outer rotor and the load-bearing shaft is greatly increased, and the bending moment borne by the two bearings is greatly increased. This requires a significant increase in the diameter of the load-bearing shaft, and accordingly a significant increase in the diameter of the outer rotor and the moment of inertia of the outer rotor, which will make it difficult to start the traction motor. Utility Model Content

[0006] An embodiment of the present utility model provides a traction device, comprising: a mounting frame, comprising a main body and a supporting portion, wherein the supporting portion is protruded from the main body; a load-bearing shaft, disposed on the supporting portion; a plurality of traction motors, sequentially sleeved on the load-bearing shaft along the axial direction of the load-bearing shaft; and a plurality of traction wheels, fixedly sleeved on the plurality of traction motors, wherein the plurality of traction motors are configured to drive the plurality of traction wheels to rotate.

[0007] In some exemplary embodiments, each of the traction motors includes: a first stator assembly fixedly mounted on the bearing shaft; and a first outer rotor assembly rotatably mounted on the first stator assembly, and the plurality of traction wheels are fixedly mounted on the plurality of first outer rotor assemblies in a one-to-one correspondence.

[0008] In some exemplary embodiments, the outer circumference of the first outer rotor assembly is provided with a step structure, and the inner circumference of the traction sheave is provided with a shoulder, which abuts against a step surface of the step structure in the axial direction of the bearing shaft.

[0009] In some exemplary embodiments, the plurality of traction motors include a first traction motor and a second traction motor, and the plurality of traction wheels include a first traction wheel and a second traction wheel. The first traction wheel is fixedly sleeved on the first outer rotor assembly of the first traction motor, and the second traction wheel is fixedly sleeved on the first outer rotor assembly of the second traction motor. In the axial direction of the load-bearing shaft, the step surface of the first traction motor and the step surface of the second traction motor are opposite to each other and are located between the shoulder of the first traction wheel and the shoulder of the second traction wheel.

[0010] In some exemplary embodiments, the support part includes: a first support frame, located on a side of the first traction motor facing away from the second traction motor and detachably fixed to the main body, and the load-bearing shaft movably passes through the first support frame; a second support frame, located on a side of the second traction motor facing away from the first traction motor and detachably fixed to the main body, and the load-bearing shaft movably passes through the second support frame; and a third support frame, located between the first traction motor and the second traction motor and detachably fixed to the main body, and the load-bearing shaft is fixedly passed through the third support frame.

[0011] In some exemplary embodiments, the traction device further includes: a plurality of detection mechanisms, which cooperate with the plurality of first outer rotor assemblies in a one-to-one correspondence and are configured to detect the rotational displacement of the plurality of first outer rotor assemblies in a one-to-one correspondence.

[0012] In some exemplary embodiments, each of the detection mechanisms includes a rotary transformer, which includes: a second stator assembly fixedly mounted on the bearing shaft; and a second outer rotor assembly rotatably mounted outside the second stator assembly and fixed to the first outer rotor assembly.

[0013] In some exemplary embodiments, a bearing is provided between an axial end portion of each first outer rotor assembly and the carrier shaft.

[0014] In some exemplary embodiments, the load-bearing shaft is a hollow shaft, the hollow shaft is provided with reinforced heat dissipation ribs or heat dissipation channels, and a stator winding power supply line is passed through the interior of the hollow shaft.

[0015] In some exemplary embodiments, the traction device further comprises: a plurality of brakes fixed to the support portion and matched with the plurality of traction wheels in a one-to-one correspondence, and configured to brake the plurality of traction wheels in a one-to-one correspondence.

[0016] An embodiment of the present utility model further provides an elevator, comprising the traction device described in any one of the above embodiments.

[0017] The traction device provided by the embodiment of the present invention has multiple traction motors sequentially mounted on the load-bearing shaft along the axial direction of the load-bearing shaft, multiple traction wheels fixedly mounted on the multiple traction motors and connected to the cargo box through steel wire ropes, multiple traction motors drive the multiple traction wheels to rotate, and the multiple traction wheels drive the cargo box to rise and fall through the steel wire ropes. Taking the multiple traction motors with the same rated load capacity and the same rated power as an example, theoretically, the rated load capacity of the traction device can reach the sum of the rated load capacities of the multiple traction motors, and the rated power of the traction device can reach the sum of the rated powers of the multiple traction motors. That is, this scheme realizes the functions of traction motors with extra-large rated load capacity and extra-large rated power through multiple traction motors with rated load capacity and rated power, can be used in extra-large freight elevators to replace traction motors with extra-large rated load capacity and extra-large rated power, and has the advantages of stable operation, easy disassembly and maintenance, low difficulty in arranging steel wire ropes, and easy starting.

[0018] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the structures particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0020] Figure 1 A schematic cross-sectional view of the main structure of the traction device provided in some embodiments of the present utility model;

[0021] Figure 2 and Figure 3 for Figure 1 A schematic diagram of the partial structure of the traction device shown;

[0022] Figure 4 for Figure 1 The left side structural diagram of the traction device shown;

[0023] Figure 5 for Figure 1 Schematic diagram of the three-dimensional structure of the traction device shown.

[0024] The corresponding relationship between the reference numerals and component names is as follows:

[0025] 110 main part, 120 first support frame, 130 second support frame, 140 third support frame, 200 load-bearing shaft, 210 heat dissipation reinforcement ribs, 310 first traction motor, 320 second traction motor, 330 first stator assembly, 340 first outer rotor assembly, 341 step structure, 410 first traction sheave, 420 second traction sheave, 430 shaft shoulder, 440 anti-shear bolt, 450 connecting pin, 500 detection mechanism, 510 second stator assembly, 520 second outer rotor assembly, 600 stator winding power supply line, 710 bearing, 720 first pressure cover, 730 end cover, 740 second pressure cover, 800 brake. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other in any way.

[0027] The traction device provided by the embodiment of the present utility model is as follows: Figures 1 to 5 As shown, it includes: a mounting frame, which includes a main body part 110 and a supporting part, and the supporting part is protruded from the main body part 110; a load-bearing shaft 200, which is provided on the supporting part; a plurality of traction motors, which are sequentially sleeved on the load-bearing shaft 200 along the axial direction of the load-bearing shaft 200; and a plurality of traction wheels, which are fixedly sleeved on the plurality of traction motors, and the plurality of traction motors are configured to drive the plurality of traction wheels to rotate.

[0028] The traction device comprises multiple traction motors which are sequentially sleeved on the load-bearing shaft 200 along the axial direction of the load-bearing shaft 200, multiple traction sheaves which are fixedly sleeved on the multiple traction motors and are all connected to the cargo box through steel wire ropes, the multiple traction motors drive the multiple traction sheaves to rotate, and the multiple traction sheaves drive the cargo box to rise and fall through the steel wire ropes. Taking the multiple traction motors having the same rated load capacity and the same rated power as an example, theoretically, the rated load capacity of the traction device can reach the sum of the rated load capacities of the multiple traction motors, and the rated power of the traction device can reach the sum of the rated powers of the multiple traction motors. That is, this solution realizes the functions of a traction motor with an extra-large rated load capacity and an extra-large rated power through multiple traction motors with rated load capacity and rated power, can be used in extra-large freight elevators to replace traction motors with an extra-large rated load capacity and an extra-large rated power, and has the advantages of stable operation, easy disassembly and maintenance, low difficulty in arranging steel wire ropes, and easy starting.

[0029] The steel wire ropes on the multiple traction sheaves are connected in parallel to the cargo box. If the traction motor and traction sheaves in one combination fail, the traction motors and traction sheaves in another combination can be used for emergency rescue operations. Therefore, the traction device is used in elevators to drive the elevator's cargo box to raise and lower, which improves the reliability of the elevator.

[0030] If multiple (i.e., N) traction motors have different rated load capacities and different rated powers, theoretically the rated load capacities of the traction device can reach N*minimum rated load capacities, and the rated power capacities of the traction device can reach N*minimum rated power.

[0031] In some examples, such as Figures 1 to 3 As shown, each traction motor includes a first stator assembly 330 fixedly mounted on the support shaft 200 and a first outer rotor assembly 340 rotatably mounted on the first stator assembly 330. Multiple traction sheaves are fixedly mounted on the first outer rotor assemblies 340 in a one-to-one correspondence, meaning each traction motor is an outer rotor traction motor. This solution minimizes the increase in the moment of inertia of each first outer rotor assembly 340, making starting the traction motor easier.

[0032] In some examples, such as Figures 1 to 3 As shown, the outer circumference of the first outer rotor assembly 340 is provided with a step structure 341, and the inner circumference of the traction wheel is provided with a shoulder 430. The axial shoulder 430 of the load-bearing shaft 200 abuts against the step surface of the step structure 341, and the shoulder 430 and the step structure 341 are fixedly connected by high-strength anti-shear bolts 440 and connecting pins 450 to prevent the assembled traction wheel and the first outer rotor assembly 340 from rotating relative to each other.

[0033] In some examples, such as Figures 1 to 3 、 Figure 5As shown, the plurality of traction motors include a first traction motor 310 and a second traction motor 320, and the plurality of traction wheels include a first traction wheel 410 and a second traction wheel 420. The first traction wheel 410 is fixedly mounted on the first outer rotor assembly 340 of the first traction motor 310, and the second traction wheel 420 is fixedly mounted on the first outer rotor assembly 340 of the second traction motor 320. In the axial direction of the support shaft 200, the stepped surface of the first traction motor 310 (the first outer rotor assembly 340) and the stepped surface of the second traction motor 320 (the first outer rotor assembly 340) are axially connected. 40) stepped surfaces are opposite to each other and are located between the shaft shoulder 430 of the first traction sheave 410 and the shaft shoulder 430 of the second traction sheave 420, so as to ensure that after the load-bearing shaft 200 is hoisted, the first traction sheave 410 and the second traction sheave 420 can be directly disassembled and installed without disassembling the first outer rotor assembly 340 of the first traction motor 310, the first outer rotor assembly 340 of the second traction motor 320, the first stator assembly 330 of the first traction motor 310 and the first stator assembly 330 of the second traction motor 320. Figure 1 As shown, the center distance L1 between the first traction wheel 410 and the second traction wheel 420 is set to be no less than 2m, so that the traction device has a reasonable layout, a stable structure, and is subjected to a small bending moment.

[0034] Furthermore, if Figures 1 to 5As shown, the support part includes: a first support frame 120, the first support frame 120 is located on the side of the first traction motor 310 facing away from the second traction motor 320, and is detachably fixed to the main body 110, and the bearing shaft 200 is movably passed through the first support frame 120; a second support frame 130, the second support frame 130 is located on the side of the second traction motor 320 facing away from the first traction motor 310, and is detachably fixed to the main body 110, and the bearing shaft 200 is movably passed through the second support frame The support frame 130 and the third support frame 140 are located between the first traction motor 310 and the second traction motor 320 and are detachably fixed to the main body 110. The bearing shaft 200 is fixedly inserted through the third support frame 140. In this solution, the bearing shaft 200 is jointly limited and supported by the first support frame 120, the second support frame 130, and the third support frame 140. This makes the bearing shaft 200 less likely to bend and deform under the action of bending moment (bending moment is bending torque). The bearing shaft 200 is movably inserted through the first support frame 120 and the second support frame 130, which can also eliminate the bending moment caused by deformation of the bearing shaft 200 due to thermal expansion and contraction. The first support frame 120 and the main part 110, the second support frame 130 and the main part 110, and the third support frame 140 and the main part 110 are disassembled so that the load-bearing shaft 200 can be lifted to realize the disassembly and installation of the first traction wheel 410, the second traction wheel 420, the first outer rotor assembly 340 of the first traction motor 310, the first outer rotor assembly 340 of the second traction motor 320, the first stator assembly 330 of the first traction motor 310, and the first stator assembly 330 of the second traction motor 320.

[0035] In some examples, such as Figures 1 to 3 As shown, the traction device also includes: multiple sets of detection mechanisms 500, which are matched with multiple first outer rotor assemblies 340 in a one-to-one correspondence. The multiple sets of detection mechanisms 500 are configured to detect the rotational displacement of multiple first outer rotor assemblies 340 one by one to ensure that the cargo box can be accurately positioned during use.

[0036] Furthermore, if Figures 1 to 3As shown, each detection mechanism 500 is a rotary transformer (rotary transformers have relatively high resolution), which includes: a second stator assembly 510, which is fixedly mounted on the support shaft 200; and a second outer rotor assembly 520, which is rotatably mounted outside the second stator assembly 510 and fixed to the first outer rotor assembly 340. The support shaft 200 is a hollow shaft, and a stator winding power supply line 600 is inserted into the hollow shaft. Stator windings are provided on both the first stator assembly 330 and the second stator assembly 510. The stator winding power supply line 600 is used to supply power to each stator winding. The stator winding power supply line 600 can be a 3-phase power supply line, a 6-phase power supply line, a 9-phase power supply line, a 12-phase power supply line, a 5-phase power supply line, a 10-phase power supply line or a 15-phase power supply line, etc., which can all achieve the purpose of this application. Its purpose does not deviate from the design idea of the present utility model and will not be repeated here. It should all fall within the scope of protection of this application.

[0037] In one embodiment, if Figure 4 and Figure 5 As shown, the inner surface of the hollow shaft (i.e., the load-bearing shaft 200) is provided with reinforced heat dissipation ribs 210 (which can be used in conjunction with a heat dissipation fan) to improve the strength of the hollow shaft and the heat dissipation performance of the traction motor and the rotary transformer, thereby ensuring the output power density of the traction motor.

[0038] In another embodiment, the hollow shaft (i.e., the load-bearing shaft 200) is provided with a heat dissipation channel, which can be a spiral channel. Cooling liquid is supplied into the spiral channel to improve the heat dissipation performance of the traction motor and the rotary transformer, thereby ensuring the output power density of the traction motor.

[0039] In some examples, such as Figures 1 to 3As shown, bearings 710 are provided between the two axial ends of each first outer rotor assembly 340 and the supporting shaft 200 . Among them, one end of the first outer rotor assembly 340 has an annular wall, and a first bearing chamber is formed between the annular wall and the load-bearing shaft 200. The other end of the first outer rotor assembly 340 is installed with an end cover 730, and a second bearing chamber is formed between the end cover 730 and the load-bearing shaft 200. The bearing 710 is located in the first bearing chamber and the second bearing chamber. The open end of the first bearing chamber (that is, the end of the first bearing chamber facing away from the first stator assembly 330) is sealed by the first pressure cover 720. The first pressure cover 720 and the peripheral wall of the first bearing chamber (that is, the first pressure cover 720 and the annular wall) are fixedly connected by high-strength anti-shear bolts 440 and the connecting pin 450. The open end of the second bearing chamber is sealed by the second pressure cover 740. The second pressure cover 740 and the peripheral wall of the second bearing chamber (that is, the second pressure cover 740 and the end cover 730) are fixedly connected by high-strength anti-shear bolts 440 and the connecting pin 450. The second outer rotor assembly 520 is fixed on the second pressure cover 740. Among them, the bearing 710 in the first bearing chamber is movably installed, and the bearing 710 in the second bearing chamber is fixedly installed. This can better eliminate the bending moment caused by the deformation of the load-bearing shaft 200 due to thermal expansion and contraction, and ensure that the first outer rotor assembly 340 and the first stator assembly 330 are always in corresponding positions, and the second outer rotor assembly 520 and the second stator assembly 510 are always in corresponding positions.

[0040] In some examples, such as Figure 4 and Figure 5 As shown, the traction device further includes: multiple sets of brakes 800, which are fixed to the support part and matched with the multiple traction wheels in a one-to-one correspondence. The multiple sets of brakes 800 are configured to brake the multiple traction wheels in a one-to-one correspondence.

[0041] In one embodiment, if Figure 4 and Figure 5 As shown, the first support frame 120 is provided with two brakes 800, which are spaced apart circumferentially around the first traction sheave 410 and are used to brake the first traction sheave 410. The second support frame 130 is provided with two brakes 800, which are spaced apart circumferentially around the second traction sheave 420 and are used to brake the second traction sheave 420. Each set of brakes 800 includes two brakes 800, each of which is a hydraulic brake.

[0042] An elevator (not shown in the figures) provided in an embodiment of the present invention includes the traction device described in any one of the above embodiments.

[0043] This elevator has all the advantages of the traction device provided by any of the above embodiments, which will not be described in detail here.

[0044] To sum up, in the traction device provided by the embodiment of the present invention, multiple traction motors are sequentially mounted on the load-bearing shaft along the axial direction of the load-bearing shaft, multiple traction wheels are fixedly mounted on the multiple traction motors and are all connected to the cargo box through steel wire ropes, multiple traction motors drive the multiple traction wheels to rotate, and the multiple traction wheels drive the cargo box to rise and fall through the steel wire ropes. Taking the multiple traction motors with the same rated load capacity and the same rated power as an example, theoretically, the rated load capacity of the traction device can reach the sum of the rated load capacities of the multiple traction motors, and the rated power of the traction device can reach the sum of the rated powers of the multiple traction motors. That is, this scheme realizes the functions of traction motors with extra-large rated load capacity and extra-large rated power through multiple traction motors with rated load capacity and rated power, can be used in extra-large freight elevators to replace traction motors with extra-large rated load capacity and extra-large rated power, and has the advantages of stable operation, easy disassembly and maintenance, low difficulty in steel wire rope arrangement, and easy starting.

[0045] In the description of the present invention, it should be noted that the terms "upper", "lower", "one side", "the other side", "one end", "the other end", "side", "relative", "four corners", "periphery", "'mouth'-shaped structure", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing "this" utility model and simplifying the description, and do not indicate or imply that the structure referred to has a specific orientation, is constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0046] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "connection," "direct connection," "indirect connection," "fixed connection," "installation," and "assembly" should be understood in a broad sense. For example, they may refer to a fixed connection, a detachable connection, or an integral connection. The terms "installation," "connection," and "fixed connection" may refer to a direct connection, an indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0047] Although the embodiments disclosed in the present invention are as described above, the contents described are merely embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art to which the present invention belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention. However, the scope of patent protection of the present invention shall still be defined by the attached claims.

Claims

1. A traction device, characterized in that: include: The mounting frame comprises a main body portion and a supporting portion, wherein the supporting portion is protruded from the main body portion; a bearing shaft, provided on the supporting portion; A plurality of traction motors are sequentially sleeved on the bearing shaft along the axial direction of the bearing shaft; and The plurality of traction wheels are fixedly mounted on the plurality of traction motors, and the plurality of traction motors are configured to drive the plurality of traction wheels to rotate.

2. The traction device according to claim 1, characterized in that: Each of the traction motors comprises: A first stator assembly is fixedly mounted on the bearing shaft; and The first outer rotor assembly is rotatably sleeved on the first stator assembly, and the plurality of traction wheels are fixedly sleeved on the plurality of first outer rotor assemblies in a one-to-one correspondence.

3. The traction device according to claim 2, characterized in that: The outer circumference of the first outer rotor assembly is provided with a step structure, and the inner circumference of the traction wheel is provided with a shaft shoulder. In the axial direction of the bearing shaft, the shaft shoulder abuts against the step surface of the step structure.

4. The traction device according to claim 3, characterized in that: The multiple traction motors include a first traction motor and a second traction motor, and the multiple traction wheels include a first traction wheel and a second traction wheel. The first traction wheel is fixedly sleeved on the first outer rotor assembly of the first traction motor, and the second traction wheel is fixedly sleeved on the first outer rotor assembly of the second traction motor. In the axial direction of the load-bearing shaft, the step surface of the first traction motor and the step surface of the second traction motor are opposite to each other and are located between the shoulder of the first traction wheel and the shoulder of the second traction wheel.

5. The traction device according to claim 4, characterized in that: The supporting portion comprises: a first support frame, located on a side of the first traction motor facing away from the second traction motor and detachably fixed to the main body, wherein the bearing shaft movably passes through the first support frame; a second support frame, located on a side of the second traction motor facing away from the first traction motor and detachably fixed to the main body, wherein the bearing shaft movably passes through the second support frame; and The third support frame is located between the first traction motor and the second traction motor and is detachably fixed to the main body. The bearing shaft is fixedly provided through the third support frame.

6. The traction device according to claim 2, characterized in that: Also includes: A plurality of detection mechanisms are matched with the plurality of first outer rotor assemblies in a one-to-one correspondence and are configured to detect the rotational displacement of the plurality of first outer rotor assemblies in a one-to-one correspondence.

7. The traction device according to claim 6, characterized in that: Each of the detection mechanisms includes a rotary transformer, and the rotary transformer includes: A second stator assembly is fixedly mounted on the bearing shaft; and The second outer rotor assembly is rotatably sleeved on the outside of the second stator assembly and fixed on the first outer rotor assembly.

8. The traction device according to claim 2, characterized in that: A bearing is provided between the axial end portion of each first outer rotor assembly and the load-bearing shaft; The bearing shaft is a hollow shaft, the hollow shaft is provided with heat dissipation reinforcement ribs or heat dissipation channels, and a stator winding power supply line is passed through the interior of the hollow shaft.

9. The traction device according to any one of claims 1 to 8, characterized in that: Also includes: A plurality of brake groups are fixedly arranged on the supporting portion and matched with the plurality of traction wheels in a one-to-one correspondence, and are configured to brake the plurality of traction wheels in a one-to-one correspondence.

10. An elevator, characterized in that: The invention comprises a traction device according to any one of claims 1 to 9.

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