CN210264470U

CN210264470U - Novel double-end motor

Info

Publication number: CN210264470U
Application number: CN201920792233.8U
Authority: CN
Inventors: 黄兆林; 蔡钦豪
Original assignee: Shenzhen Jugaoneng Electric Control Technology Co Ltd
Current assignee: Shenzhen Jugaoneng Electric Control Technology Co Ltd
Priority date: 2019-05-29
Filing date: 2019-05-29
Publication date: 2020-04-07
Anticipated expiration: 2029-05-29

Abstract

The utility model relates to a novel double-head motor, which comprises a double-head motor body; the double-end motor body comprises an output shaft; the two output ends of the double-end motor body are both provided with a transmission assembly; the transmission assembly comprises a mounting seat; the mounting seat is provided with reinforcing columns, at least three groups of fixing studs and a plurality of groups of first reinforcing rib plates; the upper surface of the mounting seat is provided with a first mounting groove; a transmission shaft and a turbine are arranged in the first mounting groove; the transmission shaft is rotationally connected with the mounting seat; both ends of the output shaft are provided with meshing teeth meshed with the turbine; the reinforcing column is provided with a first avoidance groove; the mounting seat is provided with a second avoidance groove and a third avoidance groove; the mounting seat is also provided with a clutch mechanism for performing clutch control on transmission between the transmission shaft and the turbine and a clutch driving mechanism for driving the clutch mechanism to perform clutch control on transmission between the transmission shaft and the turbine; the motor has the advantages of variable working mode, compact structure and good control effect.

Description

Novel double-end motor

Technical Field

The utility model relates to a shutter door actuating motor technical field, more specifically say, relate to a novel double-end motor.

Background

Rolling door is also called rolling door, which is a door that is formed by connecting a plurality of movable joint sheets in series and rotates up and down in a fixed slideway by taking a scroll above the door as a center. Because the double-end rotating shaft of the existing double-end motor is the final output shaft, under the condition of no additional transmission assembly, two ends of the double-end rotating shaft cannot be simultaneously used for driving the reel to rotate, and only one end of the double-end rotating shaft can be additionally provided with the chain wheel for driving; therefore, at present, a multi-purpose single-head motor is used as a driving source, a rotating shaft of the single-head motor is sleeved with a chain wheel, and a scroll is driven to rotate through the transmission of the chain wheel and a chain, so that the purpose of winding the rolling gate is realized. When the single-head motor is arranged on one side of the scroll, the volume of the rolling door is small, enough driving force can be provided, but when the single-head motor is arranged on one side of the scroll, the rolling door is large in volume, and the single-head motor is difficult to provide enough driving force.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model lies in, to prior art's above-mentioned defect, a novel double-end motor is provided.

The utility model provides a technical scheme that its technical problem adopted is:

constructing a novel double-head motor, which comprises a double-head motor body; the double-ended motor body comprises an output shaft; wherein, the two output ends of the double-head motor body are both provided with a transmission component;

the transmission assembly comprises a mounting seat fixed with the double-end motor body; the lower surface of the mounting seat is provided with a reinforcing column, at least three groups of fixing studs uniformly distributed around the reinforcing column in a circumferential manner, and a plurality of groups of first reinforcing rib plates for connecting the mounting seat and the fixing studs; the upper surface of the mounting seat is provided with a first mounting groove; a transmission shaft perpendicular to the output shaft and a turbine rotating coaxially with the transmission shaft are arranged in the first mounting groove; the transmission shaft is rotatably connected with the mounting seat; both ends of the output shaft are provided with meshing teeth meshed with the turbine;

the reinforcing column is provided with a first avoidance groove for avoiding the transmission shaft; the mounting seat is provided with a second avoidance groove for avoiding the output shaft and a third avoidance groove for avoiding the transmission shaft; the mounting seat is further provided with a clutch mechanism for clutch control of transmission between the transmission shaft and the turbine and a clutch driving mechanism for driving the clutch mechanism to clutch control of transmission between the transmission shaft and the turbine.

Preferably, the transmission shaft comprises a prismatic first transmission shaft body and a cylindrical second transmission shaft body;

the clutch mechanism comprises a linkage claw which is sleeved on the first transmission shaft body and is in sliding connection with the first transmission shaft body; the lower end of the linkage claw is provided with a longitudinally extending latch; a first clamping groove corresponding to the clamping tooth is formed in the upper surface of the turbine; the clutch driving mechanism is used for driving the linkage claw to longitudinally slide so as to carry out clutch control on transmission between the latch and the turbine.

Preferably, the clutch driving mechanism comprises a hollow ratchet wheel, a clutch handle, a torsion spring and an installation cover which are sequentially arranged from bottom to top;

the hollow ratchet wheel comprises a lower wheel body, a middle wheel body and an upper wheel body; the lower end part of the lower wheel body is attached to the turbine; four gear teeth which are uniformly distributed in the circumferential direction are arranged on the outer circular surface of the middle wheel body; the gear teeth comprise an upper plane for pressing the mounting cover and a longitudinal stopping plane; an elastic blocking piece perpendicular to the stopping plane is fixed on the inner wall of the mounting cover; the upper wheel body is provided with two first accommodating grooves which are distributed circumferentially; the first accommodating groove comprises a second accommodating groove and a third accommodating groove which are communicated; an arc-shaped boss is arranged in the third accommodating groove; the upper surface of the boss is in an arc-shaped ascending shape, and the lowest part of the upper surface is intersected with the groove bottom of the second accommodating groove; the height of the latch and the height of the upper wheel body are both smaller than the height of the boss;

the clutch handle is sleeved on the linkage claw and fixed with the linkage claw; the clutch handle is provided with two groups of climbing units; the climbing unit comprises a climbing block and a limiting bump corresponding to the second accommodating groove; the climbing block is provided with a climbing inclined plane corresponding to the upper surface of the boss;

the torsion angle of the torsion spring is not less than 90 degrees; the torsion spring comprises a main body spring section and two L-shaped action arms which are fixed with the main body spring section; the mounting cover and the clutch handle are both provided with second clamping grooves corresponding to the action arms; one of the two action arms is fixed with the clutch handle, and the other action arm is fixed with the mounting cover; a movable groove corresponding to the clutch handle and a limiting block corresponding to the clutch handle are arranged on the side surface of the mounting cover; the mounting cover is fixed with the mounting seat.

Preferably, the first transmission shaft body is a hexagonal prism.

Preferably, the latch is provided with a plurality of, and be the circumference evenly distributed.

Preferably, the second transmission shaft body is sleeved with an outer spherical bearing with a seat corresponding to the third avoiding groove; the outer spherical bearing with the seat comprises a first bearing and a first bearing seat corresponding to the bearing; the first bearing seat is fixed with the mounting seat.

Preferably, the second transmission shaft body is further provided with an upper gasket and a lower gasket which are both annular; the upper surface of the upper gasket is attached to the first transmission shaft body, and the lower surface of the upper gasket is attached to the end face of the turbine; the upper surface of the lower gasket is attached to the end face of the turbine, and the lower surface of the lower gasket is attached to the first bearing seat.

Preferably, the lower surface of the mounting seat is further provided with a second reinforcing rib plate for connecting the mounting seat and the reinforcing column; two ends of the output shaft are sleeved with second bearings; the mounting seat is provided with a second bearing seat for mounting the second bearing and a second mounting groove corresponding to the second bearing seat.

The beneficial effects of the utility model reside in that: the motor is different from the prior motor which takes the output shaft as the direct driving shaft, when the rolling door needs to be driven, the clutch mechanism is powered by the clutch driving mechanism, so that the clutch mechanism is changed from the original separation state to the closing state, the linkage of the transmission shaft and the turbine is realized, and the turbine and the output shaft synchronously move through the meshing teeth. After the driving work of the rolling gate is finished, the clutch driving mechanism can provide power for the clutch mechanism again, so that the clutch mechanism is changed from an original closed state to a separated state, and a transmission path of the transmission shaft and the turbine is cut off. If the output shaft still rotates, only the turbine rotates, so that the motion states of the transmission shaft and the turbine are independent;

the double-end motor is additionally provided with the transmission assembly, so that double-end driving is realized, and the double-end motor is arranged on one side of the roller shutter door scroll to provide enough driving force, so that electric wire consumption and installation cost are reduced, and the installation work is more time-saving; furthermore, by arranging the clutch mechanism, firstly, when the driving force is needed, the motor can drive a plurality of parts to move, and the whole device has compact structure, small occupied space and convenient transportation and installation; and secondly, when the driving force is not needed, even if the output shaft rotates accidentally, the turbine cannot change the motion state of the transmission shaft, and the safety performance is high and the control effect is good. Therefore, compared with the prior motor without the clutch mechanism, the motor has the advantages of variable working mode, compact structure and good control effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below with reference to the accompanying drawings and embodiments, wherein the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained without inventive work according to the drawings:

fig. 1 is a schematic view of the overall structure of a novel double-headed motor according to a preferred embodiment of the present invention;

fig. 2 is a schematic view of the overall structure of a novel double-headed motor according to a preferred embodiment of the present invention;

fig. 3 is an exploded view of a novel double-headed motor according to a preferred embodiment of the present invention (the double-headed motor body and the stopper are hidden);

fig. 4 is a schematic structural view (in a sectioning state) of a clutch handle in a novel double-head motor according to a preferred embodiment of the present invention

FIG. 5 is an enlarged view at A in FIG. 3;

FIG. 6 is an enlarged view at B in FIG. 3;

FIG. 7 is an enlarged view at C of FIG. 3;

FIG. 8 is an enlarged view at D of FIG. 3;

FIG. 9 is an enlarged view at E in FIG. 3;

fig. 10 is an enlarged view at F in fig. 7.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, a clear and complete description will be given below with reference to the technical solutions of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

A novel dual-head motor according to a preferred embodiment of the present invention is shown in fig. 1, and also refer to fig. 2 to 10; comprises a double-head motor body 1; the double-ended motor body 1 includes an output shaft; the two output ends of the double-head motor body 1 are both provided with a transmission component 2;

the transmission assembly 2 comprises a mounting seat 20 fixed with the double-head motor body 1; the lower surface of the mounting seat 20 is provided with a reinforcing column 21, at least three groups of fixing studs 22 which are uniformly distributed around the reinforcing column 21 in a circumferential manner, and a plurality of groups of first reinforcing rib plates 23 for connecting the mounting seat 20 and the fixing studs 22, and the mounting work of fixing the motor on a wall can be quickly finished through the matching of bolts and the fixing studs 22 so as to provide driving force for rolling the rolling door; meanwhile, the reinforcing column 21 and the first reinforcing rib 23 further enhance the overall strength of the mounting seat 20; the upper surface of the mounting seat 20 is provided with a first mounting groove 280; a transmission shaft 24 perpendicular to the output shaft and a turbine 25 rotating coaxially with the transmission shaft 24 are arranged in the first mounting groove 280; the transmission shaft 24 is rotatably connected with the mounting seat 20; both ends of the output shaft 24 are provided with meshing teeth meshed with the turbine 25;

the reinforcing column 21 is provided with a first avoidance groove 281 avoiding the transmission shaft 24; the mount 20 is provided with a second escape groove 282 for escaping the output shaft, and a third escape groove (not shown in the drawings) for escaping the transmission shaft 24; the mounting base 20 is further provided with a clutch mechanism 3 for performing clutch control on transmission between the transmission shaft 24 and the turbine 25, and a clutch driving mechanism 4 for driving the clutch mechanism 3 to perform clutch control on transmission between the transmission shaft 24 and the turbine 25, and the specific working principle of the motor is as follows:

unlike the conventional motor in which the output shaft is used as a direct drive shaft, the motor uses the transmission shaft 24 as a direct drive shaft, and when the rolling door needs to be driven, the clutch mechanism 3 is powered by the clutch drive mechanism 4, so that the clutch mechanism 3 is changed from an original separated state to a closed state, and the transmission shaft 24 and the turbine 25 are linked, and the turbine 25 and the output shaft synchronously move through meshing teeth. After the driving operation of the shutter door is completed, the clutch mechanism 3 can be powered again by the clutch driving mechanism 4, so that the clutch mechanism 3 is changed from the original closed state to the separated state, and the transmission path of the transmission shaft 24 and the turbine 25 is cut off. If the output shaft still rotates, only the turbine 25 rotates, so that the motion states of the transmission shaft 24 and the turbine 25 are independent;

the transmission assembly 2 is additionally arranged on the double-end motor, so that double-end driving is realized, and the double-end motor is arranged on one side of the roller shutter door scroll to provide enough driving force, so that electric wire consumables are reduced, the installation cost is reduced, and the installation work is more time-saving; furthermore, by arranging the clutch mechanism 3, firstly, when the driving force is needed, a plurality of parts can be driven to move by the motor, and the whole device has compact structure, small occupied space and convenient transportation and installation; secondly, when the driving force is not needed, even if the output shaft rotates accidentally, the turbine 25 can not change the motion state of the transmission shaft 24, and the safety performance is high and the control effect is good. Therefore, compared with the prior motor without the clutch mechanism, the motor has the advantages of variable working mode, compact structure and good control effect.

As shown in fig. 3, 6, and 7, the transmission shaft 24 includes a first transmission shaft body 26 having a prism shape, and a second transmission shaft body 27 having a cylindrical shape;

the clutch mechanism 3 comprises a linkage claw which is sleeved on the first transmission shaft body 26 and is in sliding connection with the first transmission shaft body; the lower end of the linkage claw is provided with a latch 30 extending longitudinally; the upper surface of the turbine 25 is provided with a first clamping groove 283 corresponding to the clamping tooth 30; clutch drive mechanism 4 is used for driving linkage claw longitudinal sliding to carry out clutch control to the transmission between latch 30 and the turbine 25, and in this motor, first transmission shaft body 26 is prismatic, is convenient for with the interlock of linkage claw, has also increased area of contact between them, can reduce wear rate between them, guarantees to have normal life, can prevent again simultaneously that linkage in-process linkage claw and first transmission shaft body 26 from taking place relative rotation, has ensured the steady of linkage process. And secondly, the synchronous linkage of the linkage claw and the turbine 25 is realized through the matching of the latch 30 and the first clamping groove 283, and the structure is simple and the cost is low. Thirdly, the clutch driving mechanism 4 provides driving force for the linkage claw to slide upwards, namely the latch 30 can be separated from the turbine 25, and the clutch mechanism 3 is in a separated state; on the contrary, the driving force for downward sliding is provided for the linkage claw, the latch 30 is engaged with the turbine 25 again to realize linkage, and the clutch mechanism 3 is in a closed state; the whole control process is easy to operate and has good control effect.

As shown in fig. 3, 4 to 8, and 10, the clutch driving mechanism 4 includes a hollow ratchet 40, a clutch handle 41, a torsion spring 42, and a mounting cover 43, which are sequentially arranged from bottom to top;

the hollow ratchet 40 comprises a lower wheel body 44, a middle wheel body 45 and an upper wheel body 46; the lower end of the lower wheel body 44 is attached to the turbine 25; four gear teeth 47 which are uniformly distributed circumferentially are arranged on the outer circular surface of the middle wheel body 45; the gear 47 comprises an upper plane 480 for pressing the mounting cover 43, and a longitudinal stop plane 481; an elastic baffle plate 48 which is vertical to the stop plane 481 is fixed on the inner wall of the mounting cover 43, when the hollow ratchet wheel 40 tends to rotate anticlockwise, the elastic baffle plate 48 vertically props against the stop plane 481 of the gear teeth 47, and at the moment, the stress point of the elastic baffle plate 48 is overlapped with the central axis of the elastic baffle plate, so that the elastic baffle plate is strong in bending resistance, can prop against the gear teeth 47 to limit the gear teeth 47 from accidentally rotating, and is good in limiting effect; conversely, when the hollow ratchet 40 rotates clockwise, the next gear tooth 47 is pushed from the side surface of the elastic blocking piece 48, and because the elastic blocking piece 48 has elasticity and can be bent under the condition of lateral force, the next gear tooth 47 can smoothly push away the elastic blocking piece 48, so that the current gear tooth 47 attached to the elastic blocking piece 48 is pushed, and the next gear tooth 47 enters until the stop plane 481 of the next gear tooth is abutted to the elastic blocking piece 48; the upper wheel body 46 is provided with two first accommodating grooves 482 which are circumferentially distributed; the first receiving groove 482 includes a second receiving groove 483 and a third receiving groove 484 that communicate; the third accommodating groove 484 is internally provided with an arc-shaped boss 49; the upper surface of the boss 49 is in an arc-shaped ascending shape, and the lowest part of the upper surface is intersected with the groove bottom of the second accommodating groove 483; the height of the latch 30 and the height of the upper wheel body 46 are both smaller than the height of the boss 49;

the clutch handle 41 is sleeved on the linkage claw and fixed with the linkage claw; the clutch handle 41 is provided with two sets of climbing units 410; the climbing unit 410 includes a climbing block 411, and a limit bump 412 corresponding to the second receiving groove 483; the climbing block 411 is provided with a climbing inclined plane 485 corresponding to the upper surface of the boss 49, the driving shaft 24 is not needed for driving, namely when the clutch mechanism 3 is in a separation state, the clutch handle 41 is rotated anticlockwise, the climbing block 411 ascends along the upper surface of the boss 49 by virtue of the climbing inclined plane 485 of the climbing block, and the boss 49 is higher than the upper wheel body 46 and still has an upward convex part, so that the limiting bump 412 is blocked and cannot be displaced; meanwhile, as the clutch handle 41 is lifted longitudinally, the linkage claw fixed with the clutch handle 41 also slides upwards along the first transmission shaft body 26, so that the latch 30 and the turbine 25 are changed from the original engagement state to the disengagement state, and the control effect that the motion states of the turbine 25 and the transmission shaft 24 are independent from each other and are not linked immediately is realized. On the contrary, the transmission shaft 24 is required to be driven, that is, the clutch mechanism 3 is required to be in a closed state, the clutch handle 41 is rotated counterclockwise again, the climbing block 411 falls from the upper wheel body 46 and enters the first accommodating groove 482, so that the climbing inclined surface 485 is attached to the upper surface of the boss 49 again, the limiting bump 412 enters the second accommodating groove 483, and the limiting bump 412 is attached to the side surface of the upper wheel body 46 and cannot be displaced; meanwhile, as the clutch handle 41 is already longitudinally descended, the linkage claw fixed with the clutch handle 41 also slides downwards along the first transmission shaft body 26, so that the latch 30 and the turbine 25 are changed from the original disengaged state to the engaged state, and linkage is realized. Therefore, the clutch handle can be switched into a separated state or a closed state in sequence by rotating anticlockwise, the whole control process is easy to operate, the structure is simple, the cost is low, and the control effect is good;

the torsion angle of the torsion spring 42 is not less than 90 degrees; the torsion spring 42 comprises a main body spring section 413 and two L-shaped action arms 414 which are fixed with the main body spring section 413; the mounting cover 43 and the clutch handle 41 are provided with second clamping grooves 486 corresponding to the action arms 414; two actuating arms 414, one of which is fixed with the clutch handle 41 and the other of which is fixed with the mounting cover 43; the side surface of the mounting cover 43 is provided with a movable groove 487 corresponding to the clutch handle 41 and a stopper 415 corresponding to the clutch handle 41; the mounting cover 43 is fixed with the mounting base 20, and the motor has the advantages that the automatic resetting of the clutch handle 41 is realized through the arrangement of the torsion spring 42, so that the labor is saved, and meanwhile, the structure is simple and the cost is low; because two sets of climbing units 410 are arranged, the clutch handle 41 needs to rotate 90 degrees when one clutch state is switched, so the torsion angle of the torsion spring 42 is set to be not less than 90 degrees, the use requirement of a user is met, and the applicability is good. Secondly, a movable space is reserved for the clutch handle 41 by arranging the movable groove 487, so that a user can push the clutch handle 41 by hands or other tools (such as an air cylinder or a push rod) conveniently, and adjustment is facilitated; meanwhile, the limiting block 415 limits the movement of the clutch handle 41, and the clutch handle 41 is prevented from directly colliding with the mounting cover 43.

As shown in fig. 7, the first transmission shaft 26 is a hexagonal prism, and the first transmission shaft 26 is set to be in a hexagonal prism shape, so that the product is more attractive, the contact area between the first transmission shaft 26 and the linkage claw is increased, the abrasion speed is reduced, the normal service life of the first transmission shaft 26 and the linkage claw can be ensured, the linkage claw and the first transmission shaft 26 can be prevented from rotating relatively in the linkage process, and the stability of the linkage process is ensured.

As shown in fig. 3, the latch 30 is provided with a plurality of latches 30 which are evenly distributed on the circumference, and the plurality of latches 30 are arranged to disperse the stress on the plurality of latches 30, so that the pressure born by each latch is small, the wear rate of the latch 30 is greatly delayed, and the normal service life of the latch is ensured.

As shown in fig. 3 and 9, the second transmission shaft body 27 is sleeved with a seated spherical outer bearing 28 corresponding to the third avoidance groove; the seated spherical-outer bearing 28 includes a first bearing (not shown), and a first bearing seat corresponding to the bearing; the first bearing seat is fixed with the mounting seat 20, the first bearing ensures that the transmission shaft 24 rotates stably and smoothly, and the turbine 25 can not shift under the pushing of the output shaft when rotating around the transmission shaft 24, so that the limiting effect is good and the movement precision is high.

As shown in fig. 3, 7 and 9, the second transmission shaft body 27 is further provided with an upper gasket 29 and a lower gasket 210 which are both annular; the upper surface of the upper gasket 29 is attached to the first transmission shaft 26, and the lower surface is attached to the end surface of the turbine 25; the upper surface of lower gasket 210 and the terminal surface laminating of turbine 25, and the lower surface and the laminating of first bearing frame, this motor set up gasket 29 and lower gasket 210 cooperation pressure and hold turbine 25, and the gasket is the rubber materials, has certain elasticity, can avoid turbine 25 in the drunkenness from top to bottom of pivoted in-process, can not press from both sides again and hinder turbine 25 itself, with low costs, protective effect is good.

As shown in fig. 1 to 3, the lower surface of the mount 20 is further provided with a second reinforcing rib 211 for connecting the mount 20 and the reinforcing column 21, so that the overall strength of the mount 20 is further enhanced; two ends of the output shaft are sleeved with second bearings (not shown in the figure), so that the output shaft is prevented from being in a cantilever state, and the motion of the output shaft is more stable by arranging the second bearings; the mount 20 is provided with a second bearing housing 212 for mounting a second bearing, and a second mounting groove 284 corresponding to the second bearing housing 212.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are considered to be within the scope of the invention as defined by the following claims.

Claims

1. A novel double-head motor comprises a double-head motor body; the double-ended motor body comprises an output shaft; the double-head motor is characterized in that transmission components are arranged at two output ends of the double-head motor body;

2. The novel double-headed motor according to claim 1, wherein the transmission shaft comprises a prismatic first transmission shaft body, and a cylindrical second transmission shaft body;

3. The novel double-end motor is characterized in that the clutch driving mechanism comprises a hollow ratchet wheel, a clutch handle, a torsion spring and a mounting cover which are arranged in sequence from bottom to top;

4. The new double-ended motor as claimed in claim 2, wherein said first transmission shaft body is a hexagonal prism.

5. The novel double-ended motor as claimed in claim 2, wherein said latch is provided in plurality and circumferentially evenly distributed.

6. The novel double-headed motor according to claim 2, wherein the second transmission shaft body is sleeved with a seated outer spherical bearing corresponding to the third avoidance groove; the outer spherical bearing with the seat comprises a first bearing and a first bearing seat corresponding to the bearing; the first bearing seat is fixed with the mounting seat.

7. The novel double-ended motor as claimed in claim 6, wherein the second transmission shaft body is further provided with an upper gasket and a lower gasket which are both annular; the upper surface of the upper gasket is attached to the first transmission shaft body, and the lower surface of the upper gasket is attached to the end face of the turbine; the upper surface of the lower gasket is attached to the end face of the turbine, and the lower surface of the lower gasket is attached to the first bearing seat.

8. The novel double-ended motor as claimed in claim 1, wherein a second reinforcing rib is further provided on a lower surface of said mounting base for connecting said mounting base and said reinforcing post; two ends of the output shaft are sleeved with second bearings; the mounting seat is provided with a second bearing seat for mounting the second bearing and a second mounting groove corresponding to the second bearing seat.