A main shaft fatigue degree detection device for a wind turbine generator system

Abstract

The present application relates to wind driven generators, and discloses a main shaft fatigue detection device for wind driven generator units, which comprises a main shaft, a detection ring for ultrasonic flaw detection of the surface of the main shaft is sleeved on the main shaft, and mounting assemblies for mounting the detection ring and keeping relative static when the main shaft rotates are further arranged at both ends of the main shaft, driving assemblies for driving the detection ring to reciprocate are arranged on the mounting assemblies, a speed reducer for adjusting the rotating speed is further arranged between the driving ring gear and the driving screw, and a connection mechanism for connecting the input end of the speed reducer with the driving ring gear is arranged in the speed reducer. The present application can realize intermittent scanning detection of the surface of the main shaft in the horizontal direction without stopping the rotation of the main shaft, realizes intelligent shaft flaw detection, does not affect the power generation efficiency of the main shaft, further improves the practicability of the detection device as a whole, and can also adapt to the change of the shaft diameter of different sections of the main shaft and realize adaptive fast clamping and mounting.

Description

Technical Field

[0001] This invention relates to wind turbines, specifically to a fatigue testing device for the main shaft of a wind turbine generator set. Background Technology

[0002] A wind turbine is an electrical device that converts wind energy into mechanical work, which drives a rotor to rotate and ultimately outputs alternating current (AC). A wind turbine generally consists of a wind turbine rotor, a generator (including its components), a directional control unit (tail fin), a tower, a speed-limiting safety mechanism, and an energy storage device. The working principle of a wind turbine is relatively simple: the wind turbine rotates under the influence of wind, converting the kinetic energy of the wind into the mechanical energy of the main shaft, which in turn drives the generator to rotate and generate electricity. Broadly speaking, wind energy is also solar energy, so a wind turbine can also be described as a thermal energy generator that uses the sun as a heat source and the atmosphere as a working medium.

[0003] The main shaft of a wind turbine is formed directly from steel ingots. The shaft axis should be aligned with the centerline of the ingot as much as possible, and sufficient material should be removed from both ends of the ingot to ensure the main shaft is free from shrinkage cavities, severe segregation, and other harmful defects. In existing technologies, the main shaft of a wind turbine operates for extended periods, making it prone to metal fatigue, which can lead to cracks in severe cases, jeopardizing the normal operation of the wind turbine. However, due to the special installation position of the main shaft and its continuous rotation, there is currently no specific testing mechanism capable of real-time inspection of the main shaft surface. Therefore, this application discloses a wind turbine main shaft fatigue testing device to meet the surface inspection requirements of wind turbine main shafts. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a fatigue testing device for the main shaft of a wind turbine generator set, which has advantages such as adaptability to the main shaft diameter and rapid installation, and solves a series of problems in the prior art, such as the inconvenience of real-time monitoring of the surface of the wind turbine generator main shaft.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a fatigue testing device for the main shaft of a wind turbine generator set, comprising a main shaft for the operation of the wind turbine generator, a detection ring for detecting the real-time surface condition of the main shaft is fitted on the main shaft, an ultrasonic flaw detection mechanism capable of omnidirectional detection of the surface of the main shaft is installed inside the detection ring, and mounting components for mounting the detection ring are provided at both ends of the main shaft, the mounting components being able to remain relatively stationary when the main shaft rotates;

[0008] The mounting assembly is further provided with a drive assembly for driving the detection ring to reciprocate in the horizontal direction. The drive assembly includes an indirectly connected drive gear ring and a drive screw. The detection ring is threaded onto the drive screw. The drive gear ring is fixedly sleeved on the outer wall of the main shaft. A speed reducer for adjusting the rotation speed is also provided between the drive gear ring and the drive screw. When the drive gear ring rotates, it can drive the drive screw to rotate through the speed reducer. The speed reducer is provided with a connecting mechanism that controls the connection between its input end and the drive gear ring.

[0009] Preferably, both ends of the spindle are fixedly fitted with fixed bearings of different sizes, and the outer wall of the fixed bearing is fixedly fitted with a rubber pad that is compatible with the mounting assembly.

[0010] Preferably, the mounting assembly includes limiting discs located at both ends of the main shaft. Both limiting discs are coaxially distributed with the main shaft, and both limiting discs have multiple evenly distributed sliding slots. Each of the multiple sliding slots has a limiting block that is adapted to the corresponding sliding slot. At the same relative position, the ends of the multiple limiting blocks that are close to each other are fixedly connected to a rubber clamp that can contact the corresponding rubber pad.

[0011] Preferably, each of the two limiting discs has a tray coaxial with the corresponding limiting disc fixedly connected to its outer wall by multiple connecting rods, and each of the two trays has two corresponding limiting protrusions fixedly connected to its inner wall, with a counterweight slidably fitted inside each of the two limiting protrusions at the same relative position.

[0012] Preferably, each of the two limiting discs has a rotating cavity that communicates with a plurality of sliding slots at corresponding positions. A protruding ring is fixedly connected to one inner wall of each of the two rotating cavities. A turntable is rotatably sleeved on each of the two protruding rings, and a coil spring drive groove is provided on each of the two turntables.

[0013] Multiple limiting blocks at the same relative position are fixedly connected to a driving protrusion in the turntable on one side of the corresponding limiting disk. When the turntable rotates, it can drive multiple coil spring driving slots to drive one end of multiple driving protrusions at the same relative position to move closer or further away from each other.

[0014] Preferably, one side of each of the two turntables is provided with an annular groove, and an internal gear ring is fixedly sleeved on the inner wall of each of the two annular grooves. A drive motor is fixedly installed on the side of each of the two limiting discs that are close to each other, and the output shafts of the two drive motors are rotatably sleeved on the corresponding limiting discs and extend into the corresponding annular grooves respectively. The end of the output shafts of the two drive motors that extends into the corresponding annular grooves is fixedly sleeved with a drive gear that meshes with the corresponding internal gear ring.

[0015] Preferably, the two limiting discs are fixedly connected to the same horizontal guide rod on the side that is close to each other by a coupling, and the detection ring is slidably sleeved on the horizontal guide rod.

[0016] Preferably, the reducer is fixedly mounted on one of the limiting disks, and the output end of the reducer can mesh with the driving gear ring through the connecting mechanism. The output end of the reducer is fixedly connected to one end of the driving screw through a coupling, and the other end of the driving screw is rotatably connected to another limiting disk.

[0017] (III) Beneficial Effects

[0018] Compared with the prior art, the present invention provides a fatigue testing device for the main shaft of a wind turbine generator set, which has the following advantages:

[0019] 1. This wind turbine generator set main shaft fatigue testing equipment, through the control of the connecting mechanism, enables the input end of the reducer to mesh with the active gear ring. After the reducer reduces speed, the output end of the reducer drives the drive screw to rotate, causing the inspection ring to reciprocate horizontally under the horizontal guidance of the horizontal guide rod. This allows for all-around ultrasonic flaw detection of the outer wall of the main shaft. Notably, the reducer should have a one-way reset component that can independently drive the drive screw to reverse. When the inspection ring moves to the thinner end of the main shaft, it can disengage from the reducer and the active gear ring through the connecting mechanism and activate the one-way reset component. This allows the drive screw to reverse and reset the inspection ring. Combined with the linkage between the main shaft and the active gear ring, and the reducer's deceleration and reset action, the inspection ring can perform intermittent scanning detection of the main shaft surface in the horizontal direction without stopping the main shaft's rotation. This achieves intelligent main shaft flaw detection without affecting the main shaft's power generation efficiency, further improving the overall practicality of the testing equipment.

[0020] 2. When installing the fatigue testing equipment for the main shaft of this wind turbine generator set, after the thicker end of the main shaft is installed, the entire testing equipment is fitted onto the main shaft through the thinner end. The drive motors at both ends are controlled to run synchronously, thereby driving the drive gear to rotate. This, in turn, causes the internal gear ring to rotate, which in turn drives the turntables inside the limit plates at both ends to rotate. Under the guidance of the corresponding sliding slots, the ends of multiple limit blocks at the same relative position move closer to each other until multiple rubber clamps make tight contact with the rubber pads on the corresponding fixed bearings, clamping the main shaft. The drive motor stops running, thus completing the installation of the limit plates at both ends and the middle testing ring. In this process, installation is convenient, and it can also adapt to the changes in shaft diameter at different sections of the main shaft, achieving adaptive and rapid clamping installation. This improves the applicability of the testing equipment and expands its practicality. Attached Figure Description

[0021] Figure 1 This is a first-view three-dimensional structural diagram of the present invention;

[0022] Figure 2 This is a schematic diagram of the second-view three-dimensional structure of the present invention;

[0023] Figure 3 This is a cross-sectional perspective view of the installation component of the present invention;

[0024] Figure 4 This is a schematic diagram of the three-dimensional structure of the main shaft of the present invention;

[0025] Figure 5 This is a three-dimensional structural diagram of the installation component of the present invention, cut open from another perspective.

[0026] Figure 6 This is a cross-sectional three-dimensional structural diagram of the limiting disc of the present invention;

[0027] Figure 7 This is a schematic diagram of the internal three-dimensional structure of the limiting disk of the present invention;

[0028] Figure 8 This is a three-dimensional structural diagram of the speed reducer of the present invention.

[0029] In the diagram: 1. Main shaft; 2. Detection ring; 3. Fixed bearing; 4. Tray; 5. Limiting plate; 6. Limiting block; 7. Rubber clamp; 8. Rotating cavity; 9. Turntable; 10. Coil spring drive groove; 11. Drive protrusion; 12. Internal gear ring; 13. Drive motor; 14. Limiting protrusion; 15. Counterweight; 16. Drive gear ring; 17. Reducer; 18. Drive screw; 19. Horizontal guide rod. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] As described in the background section, there are shortcomings in the existing technology. In order to solve the above-mentioned technical problems, this application proposes a fatigue testing device for the main shaft of a wind turbine generator set.

[0032] In one typical implementation of this application, such as Figure 1-8 As shown, a fatigue testing device for the main shaft of a wind turbine generator set includes a main shaft 1 for operating the wind turbine generator. A detection ring 2 is fitted onto the main shaft 1 to detect the real-time surface condition of the main shaft 1. An ultrasonic flaw detection mechanism capable of omnidirectional detection of the surface of the main shaft 1 is installed inside the detection ring 2. Mounting assemblies for mounting the detection ring 2 are also provided at both ends of the main shaft 1. The mounting assemblies remain relatively stationary when the main shaft 1 rotates. The mounting assemblies include limiting discs 5 located at both ends of the main shaft 1. Both limiting discs 5 are coaxially distributed with the main shaft 1, and each limiting disc 5 has multiple evenly distributed sliding slots. Each groove is fitted with a limiting block 6 that is compatible with the corresponding sliding groove. Multiple limiting blocks 6 at the same relative position are fixedly connected to rubber clamps 7 that can contact the corresponding rubber pads at their close ends. When installing the main shaft 1, after the larger diameter end of the main shaft 1 is installed, the entire installation assembly is fitted onto the outer wall of the main shaft 1, and then the other end of the main shaft 1 is connected to the fan blade of the wind turbine, thereby realizing the quick installation of the detection ring 2. In addition, when the overall installation is achieved by multiple limiting blocks 6, it can also adapt to different widths of the corresponding sections on the main shaft 1, improving the practicality of the detection ring 2 during installation.

[0033] Both ends of the main shaft 1 are fixedly sleeved with fixed bearings 3 of different sizes. The outer wall of the fixed bearing 3 is fixedly sleeved with rubber pads that are compatible with the mounting components. At the same time, when the rubber clamp 7 is used to clamp the outer wall of the main shaft 1, compared with the rigid clamping method, the clamping force between the mounting components and the outer wall of the main shaft 1 can be increased, preventing the mounting components from accidentally rotating the detection ring 2 on the main shaft 1, thus improving the overall stability of the device.

[0034] Each of the two limiting discs 5 has a tray 4 coaxial with the corresponding limiting disc 5 fixedly connected to its outer wall by multiple connecting rods. Each of the two trays 4 has two corresponding limiting protrusions 14 fixedly connected to its inner wall. Each of the two limiting protrusions 14 at the same relative position has a counterweight 15 slidably sleeved inside it. By setting the counterweight 15, the limiting discs 5 at both ends can be kept relatively fixed with the position of the main shaft 1, preventing the limiting discs 5 at both ends from rotating with the rotation of the main shaft 1, thereby achieving the stability of the detection ring 2 during operation and ensuring the accuracy of the detection effect. At the same time, it also facilitates the reciprocating movement of the detection ring 2 in the horizontal direction.

[0035] The mounting assembly also includes a drive assembly for driving the detection ring 2 to reciprocate horizontally. The drive assembly comprises an indirectly connected drive gear ring 16 and drive screw 18. The detection ring 2 is threaded onto the drive screw 18, and the drive gear ring 16 is fixedly fitted onto the outer wall of the main shaft 1. A speed reducer 17 for adjusting the rotational speed is also provided between the drive gear ring 16 and the drive screw 18. When the drive gear ring 16 rotates, it can drive the drive screw 18 to rotate through the speed reducer 17. The speed reducer 17 contains a coupling that controls the connection between its input end and the drive gear ring 16. The connecting mechanism consists of two limiting discs 5, each with a horizontal guide rod 19 fixedly connected to the side closest to each other via a coupling. The detection ring 2 is slidably fitted onto the horizontal guide rod 19. A reducer 17 is fixedly mounted on one of the limiting discs 5, and the output end of the reducer 17 can mesh with the driving gear ring 16 via a connecting mechanism. The output end of the reducer 17 is fixedly connected to one end of the drive screw 18 via a coupling, and the other end of the drive screw 18 is rotatably connected to the other limiting disc 5. After the mounting assembly is installed, the main shaft 1 rotates, controlling... The operating mechanism engages the input end of the reducer 17 with the driving gear ring 16. After reduction by the reducer 17, its output end drives the drive screw 18 to rotate. This causes the detection ring 2 to reciprocate horizontally under the guidance of the horizontal guide rod 19, thus performing omnidirectional ultrasonic testing on the outer wall of the main shaft 1. It is worth noting that the reducer 17 should have a one-way reset component that can independently reverse the drive screw 18. When the detection ring 2 moves to the thinner end of the main shaft 1... The connection between the reducer 17 and the drive gear ring 16 can be disengaged through the connecting mechanism, and the one-way reset component can be activated. This allows the drive screw 18 to reverse and drive the detection ring 2 to achieve reset. In conjunction with the linkage between the main shaft 1 and the drive gear ring 16, as well as the deceleration and reset function of the reducer 17, the detection ring 2 can perform intermittent scanning detection on the surface of the main shaft 1 in the horizontal direction without stopping the rotation of the main shaft 1. This achieves intelligent flaw detection of the main shaft 1 without affecting the power generation efficiency of the main shaft 1, further improving the overall practicality of the detection equipment.

[0036] In a preferred embodiment of this invention, each of the two limiting discs 5 has a rotating cavity 8 that communicates with multiple sliding slots at corresponding positions. A protruding ring is fixedly connected to one inner wall of each of the two rotating cavities 8, and a turntable 9 is rotatably mounted on each of the two protruding rings. Each turntable 9 has a coil spring drive groove 10. Multiple limiting blocks 6 at the same relative position are fixedly connected to a drive protrusion 11 within the turntable 9 on one side of their respective limiting discs 5. When the turntable 9 rotates, it can drive the multiple coil spring drive grooves 10 to drive the same... Multiple drive protrusions 11 in relative positions have one end approaching or moving away from each other. Two turntables 9 are also provided with annular grooves on one side, and internal gear rings 12 are fixedly sleeved on the inner walls of both annular grooves. Two limiting discs 5 are each fixedly mounted on their sides that are close to each other. The output shafts of the two drive motors 13 are rotatably sleeved on the corresponding limiting discs 5 and extend into the corresponding annular grooves. The ends of the output shafts of the two drive motors 13 extending into the corresponding annular grooves are fixedly sleeved with internal gear rings 12 that mesh with the corresponding internal gear rings 12. When installing the detection ring 2, after the thicker end of the main shaft 1 is installed, the entire detection device (including two limit discs 5 and various components between the two limit discs 5) is fitted onto the main shaft 1, and the drive motors 13 at both ends are controlled to run simultaneously. This causes the internal gear ring 12 to rotate, driving the turntables 9 inside the limit discs 5 at both ends to rotate. Under the guidance of the corresponding sliding slots, the ends of multiple limit blocks 6 at the same relative position are brought closer to each other until multiple rubber clamps 7 are in close contact with the rubber pads on the corresponding fixed bearings 3. Then the drive motors 13 stop running, thus completing the installation operation of the limit discs 5 at both ends and the detection ring 2 in the middle. This facilitates installation and can also adapt to the changes in shaft diameter at different sections of the main shaft 1, achieving adaptive clamping installation and expanding the practicality of the entire detection device. The upper part is the operation mode of the installation components in this application. In addition, multiple limit blocks 6 at the same relative position can be moved by means of cylinders, hydraulic cylinders, etc., to realize the connection operation between the detection ring 2 and the main shaft 1.

[0037] The working principle of this invention is as follows: When the detection ring 2 needs to be installed, after the thicker end of the main shaft 1 is installed, the entire detection device is fitted onto the main shaft 1 through the thinner end of the main shaft 1, and the drive motors 13 at both ends are controlled to run synchronously. The drive motors 13 drive the active gear to rotate, which in turn causes the internal gear ring 12 to rotate and drive the turntable 9 inside the limit disks 5 at both ends to rotate. Under the guidance of the corresponding sliding slots, the ends of multiple limit blocks 6 at the same relative position are brought closer to each other until multiple rubber clamps 7 are in close contact with the rubber pads on the corresponding fixed bearings 3 and clamp the main shaft 1. The drive motor 13 is then stopped, thus completing the installation operation of the limit disks 5 at both ends and the detection ring 2 in the middle. In this process, the installation is convenient and can also adapt to the changes in shaft diameter of different sections on the main shaft 1, achieving adaptive and rapid clamping installation, which improves the applicability of the detection device and expands the practicality of the entire detection device.

[0038] After the mounting components are installed, during the rotation of the spindle 1, the control mechanism operates, causing the input end of the reducer 17 to mesh with the drive gear ring 16. After reduction by the reducer 17, the output end of the reducer 17 drives the drive screw 18 to rotate. This causes the detection ring 2 to reciprocate horizontally under the horizontal guidance of the horizontal guide rod 19, thus performing all-around ultrasonic flaw detection on the outer wall of the spindle 1. It is worth noting that the reducer 17 should have a one-way reset component that can independently drive the drive screw 18 to reverse. When the detection ring 2 moves... When the spindle reaches the thinner end of the main shaft 1, the connection between the reducer 17 and the drive gear ring 16 can be disengaged through the connecting mechanism, and the one-way reset component can be activated. This allows the drive screw 18 to reverse and drive the detection ring 2 to reset. In conjunction with the linkage between the main shaft 1 and the drive gear ring 16, as well as the deceleration and reset function of the reducer 17, the detection ring 2 can perform intermittent scanning detection on the surface of the main shaft 1 in the horizontal direction without stopping the rotation of the main shaft 1. This achieves intelligent flaw detection of the main shaft 1 without affecting the power generation efficiency of the main shaft 1, further improving the overall practicality of the detection equipment.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fatigue testing device for the main shaft of a wind turbine generator set, comprising a main shaft (1) for the operation of the wind turbine generator, characterized in that: The spindle (1) is fitted with a detection ring (2) for detecting the surface condition of the spindle (1) in real time. An ultrasonic flaw detection mechanism that can detect the surface of the spindle (1) in all directions is installed inside the detection ring (2). The main shaft (1) is also provided with mounting components for mounting the detection ring (2) at both ends. The mounting components can remain relatively stationary when the main shaft (1) rotates. The mounting components include limiting disks (5) located at both ends of the main shaft (1). Both limiting disks (5) are coaxially distributed with the main shaft (1). Both limiting disks (5) are provided with multiple evenly distributed sliding slots. Each of the multiple sliding slots is slidably fitted with a limiting block (6) that matches the corresponding sliding slot. Both ends of the main shaft (1) are fixedly fitted with fixed bearings (3) of different sizes. The outer wall of the fixed bearing (3) is fixedly fitted with a rubber pad that matches the mounting components. The ends of the multiple limiting blocks (6) at the same relative position that are close to each other are fixedly connected with rubber clamps (7) that can contact the corresponding rubber pads. Each of the two limiting discs (5) has a tray (4) coaxial with the corresponding limiting disc (5) fixedly connected to its outer wall by multiple connecting rods. Each of the two trays (4) has two corresponding limiting protrusions (14) fixedly connected to its inner wall. Each of the two limiting protrusions (14) at the same relative position has a counterweight (15) slidably sleeved inside. By setting the counterweight (15), the limiting discs (5) at both ends can be kept relatively fixed with the main shaft (1), avoiding the limiting discs (5) at both ends from rotating with the rotation of the main shaft (1), thereby achieving the stability of the detection ring (2) during operation. The mounting assembly is also provided with a drive assembly for driving the detection ring (2) to reciprocate in the horizontal direction. The drive assembly includes an indirectly connected active gear ring (16) and a drive screw (18). The detection ring (2) is threaded onto the drive screw (18). The active gear ring (16) is fixedly sleeved on the outer wall of the main shaft (1). A speed reducer (17) for adjusting the rotation speed is also provided between the active gear ring (16) and the drive screw (18). When the active gear ring (16) rotates, it can drive the drive screw (18) to rotate through the speed reducer (17). The speed reducer (17) is provided with a connecting mechanism that controls its input end to connect with the active gear ring (16). The two limiting discs (5) are fixedly connected to the same horizontal guide rod (19) on the side that is close to each other by a coupling, and the detection ring (2) is slidably sleeved on the horizontal guide rod (19); The reducer (17) is fixedly installed on one of the limiting disks (5), and the input end of the reducer (17) can mesh with the driving gear ring (16) through the connecting mechanism. The output end of the reducer (17) is fixedly connected to one end of the driving screw (18) through the coupling, and the other end of the driving screw (18) is rotatably connected to another limiting disk (5). After the installation components are installed, the main shaft (1) rotates and controls the operation of the connecting mechanism, so that the input end of the reducer (17) meshes with the active gear ring (16). After the reducer (17) reduces speed, the output end of the reducer (17) drives the drive screw (18) to rotate, so that the detection ring (2) moves back and forth in the horizontal direction under the horizontal guidance of the horizontal guide rod (19), thereby performing all-round ultrasonic testing on the outer wall of the main shaft (1). The reducer (17) is equipped with a one-way reset component that can independently drive the drive screw (18) to reverse. When the detection ring (2) moves to the thinner end of the main shaft (1), it disengages from the reducer (17) and the active gear ring (16) through the connecting mechanism and activates the one-way reset component. Thus, the drive screw (18) reverses and drives the detection ring (2) to achieve reset. In conjunction with the linkage between the main shaft (1) and the active gear ring (16) and the deceleration and reset function of the reducer (17), the detection ring (2) performs intermittent scanning detection on the surface of the main shaft (1) in the horizontal direction without stopping the rotation of the main shaft (1).

2. The fatigue testing equipment for the main shaft of a wind turbine generator set according to claim 1, characterized in that: Each of the two limiting disks (5) has a rotating cavity (8) that communicates with the multiple sliding slots at the corresponding positions. A convex ring is fixedly connected to one side of the inner wall of each of the two rotating cavities (8). A turntable (9) is rotatably sleeved on the two convex rings, and a coil spring drive groove (10) is provided on each of the two turntables (9). The multiple limiting blocks (6) at the same relative position are fixedly connected to a drive protrusion (11) that is locked in the turntable (9) on one side of the corresponding limiting disk (5). When the turntable (9) rotates, it can drive the multiple coil spring drive grooves (10) to drive one end of the multiple drive protrusions (11) at the same relative position to move closer or further away from each other.

3. The fatigue testing equipment for the main shaft of a wind turbine generator set according to claim 2, characterized in that: One side of each of the two turntables (9) is provided with an annular groove, and an internal gear ring (12) is fixedly sleeved on the inner wall of each of the two annular grooves. A drive motor (13) is fixedly installed on the side of each of the two limiting discs (5) that are close to each other. The output shafts of the two drive motors (13) are rotatably sleeved on the corresponding limiting discs (5) and extend into the corresponding annular grooves respectively. The end of the output shafts of the two drive motors (13) that extends into the corresponding annular grooves is fixedly sleeved with a drive gear that meshes with the corresponding internal gear ring (12).

Images