阅读说明：本技术 风力发电机组 (Wind generating set ) 是由 孙振军 许梦华 李晓强 杨飞 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种风力发电机组,所述风力发电机组包括轮毂和主轴,所述轮毂具有连接孔,所述主轴的一端为连接端,所述主轴通过所述连接端穿设于所述连接孔连接于所述轮毂。该风力发电机组的主轴穿设在轮毂的连接孔内,并通过连接孔连接于轮毂,使得主轴与轮毂的连接点更靠近轮毂的中心,减小了弯矩,并且在同等外形尺寸的条件下,可提高主轴与轮毂的连接强度,同时也无需设置法兰盘和与法兰连接的螺栓,提高经济效益。由于没有法兰盘的阻挡,相应地可将用于支撑主轴的主轴承靠近轮毂设置,减小主轴承的载荷,提高主轴承的使用寿命。(The invention discloses a wind generating set which comprises a hub and a main shaft, wherein the hub is provided with a connecting hole, one end of the main shaft is a connecting end, and the main shaft is connected to the hub through the connecting end in a penetrating mode in the connecting hole. This wind generating set's main shaft wears to establish in wheel hub's connecting hole to connect in wheel hub through the connecting hole, make the tie point of main shaft and wheel hub more be close to wheel hub's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve the joint strength of main shaft and wheel hub, also need not to set up the flange dish simultaneously and with flange joint's bolt, improve economic benefits. Because the flange plate is not blocked, the main bearing used for supporting the main shaft can be correspondingly arranged close to the hub, the load of the main bearing is reduced, and the service life of the main bearing is prolonged.)

1. The utility model provides a wind generating set, its characterized in that, wind generating set includes wheel hub and main shaft, wheel hub has the connecting hole, the one end of main shaft is the link, the main shaft passes through the link is worn to locate the connecting hole connect in wheel hub.

2. The wind generating set of claim 1, wherein the connection end is an interference fit with the connection aperture.

3. The wind turbine of claim 1, further comprising a connection assembly by which the main shaft is removably connected to the hub.

4. The wind generating set according to claim 3, wherein the connecting assembly comprises a pressing plate and a plurality of connecting members, the pressing plate is provided with fixing holes, the connecting members penetrate through the fixing holes and are detachably connected to the end faces of the connecting ends, the number of the connecting members is multiple, the connecting members are arranged around the axis of the main shaft, the main shaft is fixed on the pressing plate through the connecting members, and the periphery of the outer side of the pressing plate is connected to the hub.

5. The wind turbine of claim 4, wherein the pressure plate is integrally formed with the hub.

6. The wind generating set according to claim 4, wherein an edge of the pressure plate abuts against an inner wall of the hub, the pressure plate is connected to the hub by a plurality of bolts, and the plurality of bolts are arranged around the main shaft.

7. The wind turbine of claim 4, wherein the connection end is splined to the hub.

8. The wind turbine of claim 4, wherein the connecting end has an outer diameter that decreases in a direction toward the hub, and the connecting hole is fitted to the connecting end.

9. The wind turbine of claim 4, wherein the coupling assembly further comprises a limiting member disposed between the coupling end and the hub for limiting the relative rotation between the main shaft and the hub.

10. The wind generating set according to claim 9, wherein the spindle and the hub are each provided with a key groove, the key groove is located on a joint surface of the spindle and the hub, the limiting member is located in the key groove, one end of the limiting member is clamped in the key groove on the hub, and the other end of the limiting member is clamped in the key groove on the spindle.

Technical Field

The invention relates to a wind generating set.

Background

The wind generating set mainly comprises a tower and a wind wheel arranged on the tower. As shown in fig. 1, the wind wheel includes a main shaft 2 ', a hub 1', and blades, the blades are mounted on the hub 1 ', one end of the main shaft 2' is connected to the hub 1 ', and the other end of the main shaft 2' is used for transmitting the rotation of the wind wheel to a generator.

The outer surface of the hub 1 ' is provided with a connecting end surface, one end of the main shaft 2 ' is provided with a flange 21 ', and the flange 21 ' of the main shaft 2 ' is connected with the connecting end surface of the hub. Currently, in order to increase the power of the generator set, the size of the blades is usually increased, so that the size of the hub 1 'and the size of the main shaft 2' and the flange 21 'on the main shaft 2' are increased. In order to reduce the influence of fatigue load on the journal of the main shaft 2 ', a larger flange fillet is arranged between the flange plate 21' and the main shaft 2 ', so that the distance between the main bearing 4' for supporting the main shaft 2 'and the connecting end surface of the hub 1' is larger, the load of the main bearing 4 'is increased, and the service life of the main bearing 4' is shortened. Meanwhile, the weight of the wind wheel is increased due to the increase of the sizes of the hub 1 ', the main shaft 2 ' and the blades, and the number of the connecting bolts 3 ' between the main shaft 2 ' and the hub 1 ' is increased, so that the manufacturing cost of the wind generating set is increased.

Disclosure of Invention

The invention aims to overcome the defects of increased weight and high cost of a wind wheel caused by poor connection mode of a main shaft and a hub in the prior art, and provides a wind generating set.

The invention solves the technical problems through the following technical scheme:

the utility model provides a wind generating set, wind generating set includes wheel hub and main shaft, wheel hub has the connecting hole, the one end of main shaft is the link, the main shaft passes through the link is worn to locate the connecting hole connect in wheel hub.

In this scheme, this wind generating set's main shaft is worn to establish in wheel hub's connecting hole to connect in wheel hub through the connecting hole, make main shaft and wheel hub's tie point more be close to wheel hub's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve main shaft and wheel hub's joint strength, also need not to set up the ring flange simultaneously and with flange joint's bolt, improve economic benefits. Because the flange plate is not blocked, the main bearing used for supporting the main shaft can be correspondingly arranged close to the hub, the load of the main bearing is reduced, and the service life of the main bearing is prolonged.

Preferably, the connecting end is in interference fit with the connecting hole.

In this scheme, link and connecting hole can adopt the assembly mode installation of cold jacket or hot jacket. By adopting the structure, the bending moment and the torque can be transmitted, the structure is simple, and the assembly is convenient.

Preferably, the wind generating set further comprises a connecting assembly, and the main shaft is detachably connected to the hub through the connecting assembly.

In this scheme, adopt above-mentioned structural style, the dismouting wind generating set of being convenient for, also be convenient for maintain maintenance main shaft and wheel hub simultaneously.

Preferably, coupling assembling includes clamp plate and connecting piece, be provided with the fixed orifices on the clamp plate, the connecting piece passes the fixed orifices can dismantle connect in the terminal surface of link, the quantity of connecting piece is a plurality of, and is a plurality of the connecting piece encircles the axis setting of main shaft, the main shaft passes through the connecting piece is fixed on the clamp plate, the outside of clamp plate connect all around in wheel hub.

In this scheme, the main shaft passes through the clamp plate to be fixed on wheel hub for the moment of torsion between transmission main shaft and the wheel hub, and the mode transmission that the connecting hole was worn to locate through the link is passed through to the moment of bending between main shaft and the wheel hub.

Preferably, the pressure plate and the hub are integrally formed.

In this scheme, adopt above-mentioned structural style, reduce the part setting, improve assembly efficiency.

Preferably, the edge of the pressure plate abuts against the inner wall of the hub, the pressure plate is connected to the hub through bolts, the number of the bolts is multiple, and the bolts are arranged around the main shaft.

In this scheme, adopt above-mentioned structural style, optimize assembly process, be convenient for dismouting main shaft and wheel hub under different operating modes. During assembly, the connecting end of the main shaft is inserted into the connecting hole, the pressing plate is fixed on the main shaft, and then the pressing plate is fixed on the hub; the pressure plate can be arranged on the hub, and then the main shaft is fixed on the pressure plate. Different assembling processes can be selected according to different installation environments, and economic benefits are improved.

Preferably, the connecting end is splined to the hub.

In this scheme, adopt above-mentioned structural style, the moment of torsion of transmission between increase main shaft and the wheel hub both, simultaneously, spline connection's mode, positioning accuracy is high, the transmission moment of torsion is big and convenient assembling. The spline connection here may be an involute spline connection or a rectangular spline connection.

Preferably, the outer diameter of the connecting end is gradually reduced along the direction close to the hub, and the connecting hole is matched with the connecting end.

In this scheme, adopt above-mentioned structural style, a pretightning force is exerted to the fixed plate in the axial direction of main shaft for the outer peripheral face of the link of main shaft compresses tightly at wheel hub's inner wall, is used for transmitting the moment of flexure, still can rely on normal force and the coefficient of friction that the conical surface produced simultaneously, produces the frictional force transmission moment of torsion, reducible main shaft terminal surface bolt's the quantity that sets up.

Preferably, the connecting assembly further includes a limiting member, and the limiting member is disposed between the connecting end and the hub and is used for limiting the mutual rotation between the spindle and the hub.

In this scheme, adopt above-mentioned structural style, the moment of torsion of transmission between increase main shaft and the wheel hub between the two, reducible main shaft terminal surface bolt's the quantity of setting. The stop member here may be a pin or a flat key.

Preferably, the spindle and the hub are both provided with a key groove, the key groove is located on a joint surface of the spindle and the hub, the limiting member is disposed in the key groove, one end of the limiting member is clamped in the key groove on the hub, and the other end of the limiting member is clamped in the key groove on the spindle.

In this scheme, adopt above-mentioned structural style, the cooperation mode of locating part and keyway, simple to operate improves assembly efficiency, and preferably, the quantity of locating part is a plurality of, and a plurality of locating parts encircle the main shaft setting.

The positive progress effects of the invention are as follows: this wind generating set's main shaft wears to establish in wheel hub's connecting hole to connect in wheel hub through the connecting hole, make the tie point of main shaft and wheel hub more be close to wheel hub's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve the joint strength of main shaft and wheel hub, also need not to set up the flange dish simultaneously and with flange joint's bolt, improve economic benefits. Because the flange plate is not blocked, the main bearing used for supporting the main shaft can be correspondingly arranged close to the hub, the load of the main bearing is reduced, and the service life of the main bearing is prolonged.

Drawings

Fig. 1 is a schematic structural diagram of a spindle and a hub in the background art of the present invention.

Fig. 2 is a schematic structural view of a spindle and a hub in embodiment 1 of the present invention.

Fig. 3 is a schematic structural view of a spindle and a hub (a pressure plate and the hub are integrally formed) in embodiment 2 of the present invention.

Fig. 4 is a partial structural diagram of fig. 3.

Fig. 5 is a schematic structural view of a spindle and a hub (a pressure plate is a separate component) in embodiment 2 of the present invention.

Fig. 6 is a schematic structural view of a splined connection between a spindle and a hub in embodiment 3 of the present invention.

FIG. 7 is a cross-sectional view of the spindle splined to the hub of FIG. 6.

Fig. 8 is a schematic structural view illustrating connection between a spindle and a hub limiting member in embodiment 4 of the present invention.

FIG. 9 is a cross-sectional view of the spindle and hub of FIG. 8.

Description of reference numerals:

reference numerals of the background art

Hub 1'

Main shaft 2'

Flange plate 21'

Bolt 3'

Main bearing 4'

Reference numerals of the figures of the present invention

Hub 1

Connecting hole 11

Spindle 2, connecting end 2a

Connecting assembly 3

Pressure plate 31

Connecting piece 32

Stopper 33

Main bearing 10

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

Example 1

As shown in fig. 2, the present embodiment discloses a wind turbine generator system, which includes a hub 1 and a main shaft 2, wherein the hub 1 has a connection hole 11, one end of the main shaft 2 is a connection end 2a, and the main shaft 2 is connected to the hub 1 through the connection end 2a by penetrating through the connection hole 11. This wind generating set's main shaft 2 wears to establish in wheel hub 1's connecting hole 11 to connect in wheel hub 1 through connecting hole 11, make main shaft 2 and wheel hub 1's tie point more be close to wheel hub 1's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve main shaft 2 and wheel hub 1's joint strength, also need not to set up the flange dish simultaneously and with flange joint's bolt, improve economic benefits. Due to the absence of the stop of the flange, the main bearing 10 (as shown in fig. 3) for supporting the main shaft 2 may be correspondingly arranged close to the hub 1, reducing the load of the main bearing 10 and increasing the service life of the main bearing 10.

Specifically, the connecting end 2a and the connecting hole 11 can be installed in an assembling mode of a cold sleeve or a hot sleeve, interference fit of the connecting end 2a and the connecting hole 11 is achieved, transmission of bending moment and torque is facilitated, the structure is simple, and assembling is convenient.

Example 2

As shown in fig. 3-5, the present embodiment discloses a wind turbine generator system, which includes a hub 1 and a main shaft 2, wherein the hub 1 has a connection hole 11, one end of the main shaft 2 is a connection end 2a, and the main shaft 2 is connected to the hub 1 through the connection end 2a passing through the connection hole 11. This wind generating set's main shaft 2 wears to establish in wheel hub 1's connecting hole 11 to connect in wheel hub 1 through connecting hole 11, make main shaft 2 and wheel hub 1's tie point more be close to wheel hub 1's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve main shaft 2 and wheel hub 1's joint strength, also need not to set up the flange dish simultaneously and with flange joint's bolt, improve economic benefits. Due to the absence of the stop of the flange, the main bearing 10 (as shown in fig. 3) for supporting the main shaft 2 may be correspondingly arranged close to the hub 1, reducing the load of the main bearing 10 and increasing the service life of the main bearing 10.

Wind generating set still includes coupling assembling 3, and main shaft 2 passes through coupling assembling 3 and can dismantle to be connected in wheel hub 1, and the dismouting wind generating set of being convenient for also is convenient for maintain main shaft 2 and wheel hub 1.

Specifically, coupling assembling 3 includes clamp plate 31 and connecting piece 32, is provided with the fixed orifices on the clamp plate 31, and connecting piece 32 passes the fixed orifices and can dismantle the terminal surface of connecting in link 2a, and the quantity of connecting piece 32 is a plurality of, and a plurality of connecting pieces 32 encircle the axis setting of main shaft 2, and main shaft 2 passes through connecting piece 32 to be fixed on clamp plate 31, and the outside of clamp plate 31 is connected all around in wheel hub 1. The main shaft 2 is fixed on the hub 1 through the pressure plate 31 and is used for transmitting torque between the main shaft 2 and the hub 1, and bending moment between the main shaft 2 and the hub 1 is transmitted in a mode that the connecting end 2a penetrates through the connecting hole 11. In the present embodiment, the connecting member 32 is a bolt.

As shown in fig. 3 and 4, the pressure plate 31 is integrally formed with the hub 1, so that the number of parts is reduced and the assembly efficiency is improved. As shown in fig. 5, the pressing plate 31 may also be an independent component, the edge of the pressing plate 31 abuts against the inner wall of the hub 1, the pressing plate 31 is connected to the hub 1 through bolts, the bolts are multiple in number, and the bolts are arranged around the spindle 2, so that the spindle 2 and the hub 1 can be conveniently disassembled and assembled under different working conditions, and the assembly process is optimized. During assembly, the connecting end 2a of the main shaft 2 is inserted into the connecting hole 11, the pressing plate 31 is fixed on the main shaft 2, and then the pressing plate 31 is fixed on the hub 1; the pressure plate 31 may be mounted on the hub 1, and the spindle 2 may be inserted into the coupling hole 11 and fixed to the pressure plate 31. Different assembling processes can be selected according to different installation environments, and economic benefits are improved.

Preferably, the outer diameter of the connecting end 2a is gradually reduced in a direction approaching the hub 1 (as shown in fig. 4), and the connecting hole 11 is fitted with the connecting end 2 a. The fixing plate applies a pretightening force in the axial direction of the main shaft 2, so that the outer peripheral surface of the connecting end 2a of the main shaft 2 is tightly pressed on the inner wall of the hub 1 for transmitting bending moment, and meanwhile, friction force is generated to transmit torque by means of normal force and friction coefficient generated by the conical surface, the torque transmitted by the main shaft 2 through the pressing plate 31 is reduced, and the number of bolts arranged on the end surface of the main shaft 2 can be reduced.

Example 3

As shown in fig. 6-7, the present embodiment discloses a wind turbine generator system, which includes a hub 1 and a main shaft 2, wherein the hub 1 has a connection hole 11, one end of the main shaft 2 is a connection end 2a, and the main shaft 2 is connected to the hub 1 through the connection end 2a passing through the connection hole 11. This wind generating set's main shaft 2 wears to establish in wheel hub 1's connecting hole 11 to connect in wheel hub 1 through connecting hole 11, make main shaft 2 and wheel hub 1's tie point more be close to wheel hub 1's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve main shaft 2 and wheel hub 1's joint strength, also need not to set up the flange dish simultaneously and with flange joint's bolt, improve economic benefits. Due to the absence of the stop of the flange, the main bearing 10 (as shown in fig. 3) for supporting the main shaft 2 may be correspondingly arranged close to the hub 1, reducing the load of the main bearing 10 and increasing the service life of the main bearing 10.

Wind generating set still includes coupling assembling 3, and main shaft 2 passes through coupling assembling 3 and can dismantle to be connected in wheel hub 1, and the dismouting wind generating set of being convenient for also is convenient for maintain main shaft 2 and wheel hub 1.

Specifically, coupling assembling 3 includes clamp plate 31 and connecting piece 32, is provided with the fixed orifices on the clamp plate 31, and connecting piece 32 passes the fixed orifices and can dismantle the terminal surface of connecting in link 2a, and the quantity of connecting piece 32 is a plurality of, and a plurality of connecting pieces 32 encircle the axis setting of main shaft 2, and main shaft 2 passes through connecting piece 32 to be fixed on clamp plate 31, and the outside of clamp plate 31 is connected all around in wheel hub 1. The main shaft 2 is fixed on the hub 1 through the pressure plate 31 and is used for transmitting torque between the main shaft 2 and the hub 1, and bending moment between the main shaft 2 and the hub 1 is transmitted in a mode that the connecting end 2a penetrates through the connecting hole 11. In the present embodiment, the connecting member 32 is a bolt.

Wherein, clamp plate 31 can with wheel hub 1 integrated into one piece, reduce the part setting, improve assembly efficiency. In this embodiment, the clamp plate 31 is an individual part, and the edge butt of clamp plate 31 is at the inner wall of wheel hub 1, and clamp plate 31 passes through bolted connection on wheel hub 1, and the quantity of bolt is a plurality of, and a plurality of bolts encircle main shaft 2 and set up, are convenient for dismouting main shaft 2 and wheel hub 1 under different operating modes, optimize assembly process. During assembly, the connecting end 2a of the main shaft 2 is inserted into the connecting hole 11, the pressing plate 31 is fixed on the main shaft 2, and then the pressing plate 31 is fixed on the hub 1; the pressure plate 31 may be mounted on the hub 1, and the spindle 2 may be inserted into the coupling hole 11 and fixed to the pressure plate 31. Different assembling processes can be selected according to different installation environments, and economic benefits are improved.

Preferably, the outer diameter of the connection end 2a is gradually reduced in a direction approaching the hub 1, and the connection hole 11 is fitted with the connection end 2 a. As shown in fig. 4, the connecting end 2a and the connecting hole 11 of the hub 1 form a mutually matched conical structure, the included angle between the upper surface of the connecting end 2a and the horizontal plane is α, and the size of the included angle α is determined by a plurality of factors, such as the length of the connecting end 2a, the friction coefficient between the connecting end 2a and the inner wall of the hub 1, and the pressing force applied to the connecting end 2a along the axial direction. The fixing plate applies a pretightening force in the axial direction of the main shaft 2, so that the outer peripheral surface of the connecting end 2a of the main shaft 2 is tightly pressed on the inner wall of the hub 1 for transmitting bending moment, and meanwhile, friction force is generated to transmit torque by means of normal force and friction coefficient generated by the conical surface, the torque transmitted by the main shaft 2 through the pressing plate 31 is reduced, and the number of bolts arranged on the end surface of the main shaft 2 can be reduced.

To further increase the torque transmitted between the main shaft 2 and the hub 1, the connection end 2a is splined to the connection hole 11 of the hub 1. The spline connection has the advantages of high positioning precision, large transmission torque and convenience in assembly. The spline connection here may be an involute spline connection or a rectangular spline connection.

Example 4

As shown in fig. 8-9, the present embodiment discloses a wind turbine generator system, which includes a hub 1 and a main shaft 2, wherein the hub 1 has a connection hole 11, one end of the main shaft 2 is a connection end 2a, and the main shaft 2 is connected to the hub 1 through the connection end 2a passing through the connection hole 11. This wind generating set's main shaft 2 wears to establish in wheel hub 1's connecting hole 11 to connect in wheel hub 1 through connecting hole 11, make main shaft 2 and wheel hub 1's tie point more be close to wheel hub 1's center, reduced the moment of flexure, and under the condition of equal overall dimension, can improve main shaft 2 and wheel hub 1's joint strength, also need not to set up the flange dish simultaneously and with flange joint's bolt, improve economic benefits. Due to the absence of the stop of the flange, the main bearing 10 (as shown in fig. 3) for supporting the main shaft 2 may be correspondingly arranged close to the hub 1, reducing the load of the main bearing 10 and increasing the service life of the main bearing 10.

Wind generating set still includes coupling assembling 3, and main shaft 2 passes through coupling assembling 3 and can dismantle to be connected in wheel hub 1, and the dismouting wind generating set of being convenient for also is convenient for maintain main shaft 2 and wheel hub 1.

Specifically, coupling assembling 3 includes clamp plate 31 and connecting piece 32, is provided with the fixed orifices on the clamp plate 31, and connecting piece 32 passes the fixed orifices and can dismantle the terminal surface of connecting in link 2a, and the quantity of connecting piece 32 is a plurality of, and a plurality of connecting pieces 32 encircle the axis setting of main shaft 2, and main shaft 2 passes through connecting piece 32 to be fixed on clamp plate 31, and the outside of clamp plate 31 is connected all around in wheel hub 1. The main shaft 2 is fixed on the hub 1 through the pressure plate 31 and is used for transmitting torque between the main shaft 2 and the hub 1, and bending moment between the main shaft 2 and the hub 1 is transmitted in a mode that the connecting end 2a penetrates through the connecting hole 11. In the present embodiment, the connecting member 32 is a bolt.

Wherein, clamp plate 31 can with wheel hub 1 integrated into one piece, reduce the part setting, improve assembly efficiency. In this embodiment, the clamp plate 31 is an individual part, and the edge butt of clamp plate 31 is at the inner wall of wheel hub 1, and clamp plate 31 passes through bolted connection on wheel hub 1, and the quantity of bolt is a plurality of, and a plurality of bolts encircle main shaft 2 and set up, are convenient for dismouting main shaft 2 and wheel hub 1 under different operating modes, optimize assembly process. During assembly, the connecting end 2a of the main shaft 2 is inserted into the connecting hole 11, the pressing plate 31 is fixed on the main shaft 2, and then the pressing plate 31 is fixed on the hub 1; the pressure plate 31 may be mounted on the hub 1, and the spindle 2 may be inserted into the coupling hole 11 and fixed to the pressure plate 31. Different assembling processes can be selected according to different installation environments, and economic benefits are improved.

Preferably, the outer diameter of the connection end 2a is gradually reduced in a direction approaching the hub 1, and the connection hole 11 is fitted with the connection end 2 a. The fixing plate applies a pretightening force in the axial direction of the main shaft 2, so that the outer peripheral surface of the connecting end 2a of the main shaft 2 is tightly pressed on the inner wall of the hub 1 for transmitting bending moment, and meanwhile, friction force is generated to transmit torque by means of normal force and friction coefficient generated by the conical surface, the torque transmitted by the main shaft 2 through the pressing plate 31 is reduced, and the number of bolts arranged on the end surface of the main shaft 2 can be reduced.

On this basis, the connecting assembly 3 further includes a limiting member 33, and the limiting member 33 is disposed between the connecting end 2a and the hub 1, and is used for limiting the mutual rotation between the main shaft 2 and the hub 1, so as to increase the torque transmitted between the main shaft 2 and the hub 1, and reduce the number of bolts disposed on the end surface of the main shaft 2. The stop 33 here may be a pin or a flat key.

In this embodiment, the key slots are disposed on the main shaft 2 and the hub 1, the key slots are located on the joint surface of the main shaft 2 and the hub 1, the limiting member 33 is disposed in the key slots, one end of the limiting member 33 is clamped in the key slot on the hub 1, and the other end of the limiting member 33 is clamped in the key slot on the main shaft 2. The stopper 33 is a flat key. The locating part 33 and the key groove are matched, so that the installation is convenient, and the assembly efficiency is improved. Preferably, the number of the limiting members 33 is plural, and the plural limiting members 33 are disposed around the main shaft 2. Further, the key groove extends in the length direction from the end of the main shaft 2, facilitating the fitting of a flat key.

While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.