A brushless outer rotor motor and a curtain driving device

Abstract

This application provides a brushless external rotor motor and a curtain drive device. The brushless external rotor motor includes a motor housing, an output shaft, bearings, an inner stator, and an outer rotor. The bearings and the inner stator are fixedly disposed inside the motor housing. The output shaft is rotatably mounted on the bearings and its upper end passes through the output shaft hole at the upper end of the motor housing. The outer rotor is fixedly disposed at the lower end of the output shaft. The motor housing of this application covers the outer rotor and serves to fix it in place, axially fixing the outer rotor inside the outer rotor housing. There is a gap between the outer rotor and the inner wall of the motor housing, which can reduce noise and lower the noise during the operation of the outer rotor. The motor is assembled and installed through the motor housing, which can be easily connected to the gearbox. It has the advantages of high integration and low noise.

Description

Technical Field

[0001] This application relates to the field of electric curtains, specifically to a brushless external rotor motor and a curtain drive device. Background Technology

[0002] With the continuous development of smart homes, electric curtains are being used more and more widely. The reason why electric curtains can be operated electrically is mainly because they are equipped with a drive device to drive the opening and closing of the curtains.

[0003] Existing curtain drive mechanisms often suffer from problems such as complex assembly and high noise levels. Therefore, there is an urgent need to further improve existing electric curtain drive mechanisms. Utility Model Content

[0004] This utility model aims to solve the problems of complex assembly and high noise in existing curtain drive devices. On the one hand, this application provides a brushless external rotor motor with advantages such as high integration and low noise.

[0005] To achieve the above objectives, this application provides a brushless external rotor motor, which includes a motor housing, an output shaft hole at the upper end of the motor housing, a bearing and an inner stator fixedly disposed inside the motor housing, an output shaft rotatably disposed on the bearing, the upper end of the output shaft passing through the output shaft hole, an external rotor fixedly connected to the lower end of the output shaft, the motor housing covering the external rotor, and a gap between the periphery of the external rotor and the inner wall of the motor housing.

[0006] As described above, a brushless external rotor motor includes an external rotor body mounted on the lower end of the output shaft and a magnet disposed on the inner wall of the external rotor body. The magnet surrounds the inner stator, and there is a gap between the periphery of the external rotor body and the inner wall of the motor housing.

[0007] As described above, in a brushless external rotor motor, the external rotor body is bowl-shaped and the magnet is ring-shaped.

[0008] As described above, in a brushless external rotor motor, the top of the motor housing is provided with a mounting tube extending from the output shaft hole toward the center inside, and the bearing and the inner stator are both mounted on the mounting tube.

[0009] In the brushless external rotor motor described above, the bearings are installed on the inner sides of both the upper and lower ends of the mounting tube.

[0010] As described above, in a brushless external rotor motor, the inner stator includes a stator core mounted on the outside of the mounting tube and multiple sets of coil windings wound on the stator core.

[0011] As described above, a brushless external rotor motor has a wire adapter plate inside the motor housing that is electrically connected to the inner stator. The brushless external rotor motor also includes a motor wire with one end electrically connected to the wire adapter plate and the other end passing through the motor housing and electrically connected to an external power source.

[0012] As described above, a brushless external rotor motor has an upwardly protruding boss on the top of the motor housing, which is used for assembly and connection with a gearbox.

[0013] Another aspect of this application provides a curtain drive device, including the above-mentioned brushless external rotor motor and a gearbox that is drively connected to the brushless external rotor motor;

[0014] The gearbox includes an internal gear sleeve, and the bottom of the internal gear sleeve is provided with a sleeve portion that is sleeved around and assembled with the protrusion portion.

[0015] As described above, in a curtain driving device, the sleeve portion and the boss portion are assembled and connected by a snap-fit ​​structure;

[0016] The buckle structure includes several sets of buckle protrusions and buckle hook grooves that can be adapted for buckle connection. The buckle protrusions are provided on the periphery of the boss portion, and the buckle hook grooves are formed on the sleeve portion.

[0017] As described above, in a curtain driving device, the upper side of the inner toothed sleeve is provided with an output hole, and the inner wall of the inner toothed sleeve is provided with a toothed ring;

[0018] The gearbox includes a first-stage planetary disk, a second-stage planetary disk, a first-stage sun gear, a second-stage sun gear, a first-stage planetary gear set, and a second-stage planetary gear set, with the first-stage planetary disk and the second-stage planetary disk sequentially disposed within the inner gear sleeve;

[0019] The first-stage planetary gear set is rotatably located on the lower side of the first-stage planetary disk and meshes with the gear ring. The first-stage sun gear is connected to the output shaft of the brushless external rotor motor and meshes with the first-stage planetary gear set.

[0020] The secondary planetary gear set is rotatably disposed on the lower side of the secondary planetary disk and meshes with the gear ring. The secondary sun gear is fixedly disposed on the upper side of the primary planetary disk and meshes with the secondary planetary gear set. The output end of the gearbox is disposed on the upper side of the secondary planetary disk and extends out of the output hole.

[0021] The curtain drive device described above further includes a clutch that is connected to the gearbox in a transmission.

[0022] The clutch includes:

[0023] The output component has a clutch chamber on the side facing the gearbox, and the inner wall of the clutch chamber has an inwardly recessed groove;

[0024] A clutch element is disposed in the clutch cavity and is connected to the output end of the gearbox, and there is a gap between the outer wall of the clutch element and the inner wall of the clutch cavity;

[0025] An iron component is fixedly mounted on the upper side of the gearbox;

[0026] A magnetic bead is disposed in the clutch cavity, located on one side of the clutch component, and can be attracted to the iron component;

[0027] The output end of the gearbox can drive the clutch to rotate until it contacts the magnetic bead, and drive the magnetic bead to be engaged in the groove. Then, when the magnetic bead contacts the clutch and the groove respectively, it indirectly drives the output component to rotate.

[0028] As described above, in a curtain driving device, the clutch includes an elliptical driving portion for contacting the magnetic bead. The distance between the short side of the driving portion and the clutch cavity is greater than the outer diameter of the magnetic bead, and the distance between the long side of the driving portion and the clutch cavity is less than the outer diameter of the magnetic bead; and / or

[0029] The output end of the gearbox is provided with two connecting protrusions spaced apart, and a connecting groove recessed inward is provided between the two connecting protrusions. The clutch includes a drive part for contacting the magnetic bead. A connecting block that can be fitted and embedded in the connecting groove is integrally provided on the lower side of the drive part. Two connecting grooves recessed inward are provided on both sides of the connecting block. The two connecting grooves can be fitted and nested with the two connecting protrusions respectively.

[0030] Compared with the prior art, the beneficial effects of this application are as follows:

[0031] This application provides a brushless external rotor motor, which includes a motor housing, an output shaft, bearings, an inner stator, and an outer rotor. The bearings and the inner stator are fixedly disposed inside the motor housing. The output shaft is rotatably mounted on the bearings and its upper end passes through the output shaft hole at the upper end of the motor housing. The outer rotor is fixedly disposed at the lower end of the output shaft. The motor housing of this application covers the outer rotor and serves to fix it in place, axially fixing the outer rotor inside the outer rotor housing. There is a gap between the outer rotor and the inner wall of the motor housing, which can reduce noise during the operation of the outer rotor. The motor is assembled and installed through the motor housing, which can be easily connected to the gearbox. It has the advantages of high integration and low noise.

[0032] This application also provides a curtain drive device, which includes at least a brushless external rotor motor and a gearbox connected in sequence. The bottom of the gearbox's inner gear sleeve is directly fitted onto the top of the motor housing of the brushless external rotor motor and assembled and connected by a snap-fit ​​structure to form a stable power output. This application can achieve the purpose of quick assembly, has a simple and compact structure, and rationally arranges the internal space of the device, which is conducive to reducing the overall structure of the device and facilitating product assembly and application. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0034] Figure 1 This is a cross-sectional schematic diagram of a brushless external rotor motor according to an embodiment of this application;

[0035] Figure 2 This is an exploded view of a brushless external rotor motor according to an embodiment of this application;

[0036] Figure 3 This is an exploded view of a brushless external rotor motor according to another embodiment of this application;

[0037] Figure 4 This is a schematic diagram of the structure of a motor housing in an embodiment of this application.

[0038] Figure 5 This is a schematic diagram of the structure of a curtain driving device according to an embodiment of this application;

[0039] Figure 6 This is a cross-sectional schematic diagram of a curtain driving device according to an embodiment of this application;

[0040] Figure 7 This is an exploded view of a curtain driving device according to an embodiment of this application;

[0041] Figure 8 This is an exploded view of a curtain driving device according to an embodiment of this application;

[0042] Figure 9 This is an exploded view of the gearbox in an embodiment of this application;

[0043] Figure 10 This is an exploded view of the gearbox from another perspective in an embodiment of this application. Detailed Implementation

[0044] This application provides a brushless external rotor motor 2, which includes a motor housing 21, an output shaft 22, a bearing 23, an inner stator 24, and an external rotor 25. The upper end of the motor housing 21 is provided with an output shaft hole 210. The brushless external rotor motor 2 also includes a bearing 23 and an inner stator 24 fixedly disposed in the motor housing 21. An output shaft 22 is rotatably disposed on the bearing 23. The upper end of the output shaft 22 passes through the output shaft hole 210. The lower end of the output shaft 22 is fixedly disposed with an external rotor 25. The motor housing 21 covers the external rotor 25, and there is a gap between the periphery of the external rotor 25 and the inner wall of the motor housing 25.

[0045] One embodiment of this application discloses a brushless external rotor motor, comprising a motor housing, an output shaft, bearings, an inner stator, and an outer rotor. The bearings and the inner stator are fixedly disposed inside the motor housing. The output shaft is rotatably mounted on the bearings, with its upper end extending through the output shaft hole at the upper end of the motor housing. The outer rotor is fixedly disposed at the lower end of the output shaft. The motor housing of this application covers the outer rotor, serving a fixing function to axially fix the outer rotor within the outer rotor housing. A gap exists between the outer rotor and the inner wall of the motor housing, which can reduce noise during operation. The motor is assembled and installed through the motor housing, allowing for convenient connection to a gearbox. It has advantages such as high integration and low noise.

[0046] Specifically, the inner stator 24 includes a stator core 241 mounted on the outside of the mounting tube 212, and multiple sets of coil windings 242 wound on the stator core 241; the outer rotor 25 includes an outer rotor body 251 mounted on the lower end of the output shaft 22, and a magnet 252 disposed on the inner wall of the outer rotor body 251. The outer rotor body 251 is bowl-shaped, and the magnet 252 is arranged around the coil windings 242. This application uses an outer rotor brushless outer rotor motor to effectively improve the output torque. The motor housing 21 of this application covers the outer rotor 25 to achieve the following purposes: 1. To fix, that is, the outer rotor is axially fixed in the housing; 2. To reduce noise, reducing the noise when the outer rotor is running; 3. To connect, facilitating the connection of the housing to the gearbox.

[0047] Specifically, the top of the motor housing 21 is provided with a mounting tube 212 extending inward from the output shaft hole 210 to the center. Bearings 23 are mounted on the inner sides of both the upper and lower ends of the mounting tube 212, and the inner stator 24 is mounted on the outer side of the mounting tube 212. Compared to existing drive devices that use internal rotor motors and require screw locking, the brushless external rotor motor 2 of this application is a brushless external rotor motor. The inner rotor and bearings are located on the mounting tube 212 in the middle of the motor housing 21, and the outer rotor 25 rotates around the inner rotor, resulting in more stable driving and ensuring structural stability.

[0048] As a further preferred embodiment, such as Figure 2 In the illustrated embodiment, the motor housing 21 is equipped with a wire adapter plate 26 electrically connected to the inner stator 24. The brushless external rotor motor 2 also includes a motor wire 27, one end of which is electrically connected to the wire adapter plate 26, and the other end of which passes through the motor housing 21 and is electrically connected to an external power source. In existing brushless motors, the motor wire is directly electrically connected to the inner stator, which makes it easy for the wire to break when pulled out directly, thus disconnecting the power input. This application adds a wire adapter plate 26 inside the motor housing 21. By using the wire adapter plate 26 as an electrical connection medium to connect to both the inner stator 24 and the motor wire 27, the direct electrical connection between the motor wire 27 and the inner stator 24 can be avoided, improving the stability of the electrical connection and increasing the stability of the power input. Of course, the wire adapter plate 26 can be inside or outside the motor housing. As a preferred embodiment of this application, the wire adapter plate 26 is mounted on the mounting tube 212, and the input end of the coil winding 242 is electrically connected to the wire adapter plate 26.

[0049] As another embodiment of this application, such as Figure 3 In the second embodiment shown, the brushless external rotor motor 2 further includes a motor wire 27, one end of which is electrically connected to the input terminal of the coil winding 242, and the other end of which passes through the motor housing 21 and is electrically connected to an external power source. This structure is simple and can save internal space in the motor.

[0050] In a preferred embodiment of this application, the top of the motor housing 21 is provided with an upwardly protruding boss 211, which is used for assembly and connection with the gearbox. In a specific embodiment of this application, during assembly, the gearbox is fitted onto the boss 211 on the top of the motor housing 21 through its bottom, so that the two are assembled and fixed. Compared with the existing installation structure that requires brackets and other assembly connections, this application has the characteristics of convenient and quick assembly, while saving parts and enabling the device to be miniaturized.

[0051] This application embodiment also provides a curtain driving device, including a brushless external rotor motor 2, a gearbox 3 and a clutch 4 connected in sequence. The brushless external rotor motor 2 includes a motor housing 21, and the gearbox 3 includes an inner gear sleeve 31. The bottom of the inner gear sleeve 31 is fitted onto the top of the motor housing 21, and the two are assembled and connected by a snap-fit ​​structure 5.

[0052] Existing curtain drive devices, such as the Chinese patent application number 202321744701.7, disclose a motor structure including a housing, in which a motor and a gearbox are disposed, wherein the motor and the gearbox need to be connected by a mounting bracket. This structural design has the problems of complex structure and low assembly efficiency, and occupies more space in the electric curtain.

[0053] The curtain drive device of this application includes a brushless external rotor motor and a gearbox that are driven in sequence. The bottom of the inner gear sleeve of the gearbox is directly fitted onto the top of the motor housing of the brushless external rotor motor and is assembled and connected by a snap-fit ​​structure to form a stable power output. This application can achieve the purpose of quick assembly. The structure is simple and compact, and the internal space of the device is reasonably arranged, which is conducive to reducing the overall structure of the device and facilitating product assembly and application.

[0054] In a preferred embodiment of this application, the top of the motor housing 21 is provided with an upwardly protruding boss 211, and the bottom of the inner gear sleeve 31 is provided with a sleeve portion 32 that fits around the boss 211. In a specific embodiment of this application, during assembly, the inner gear sleeve 31 is fitted onto the boss 211 at the top of the motor housing 21 through the sleeve portion 32 at the bottom, and the two are assembled and fixed by the snap-fit ​​structure 5. Compared with the existing installation structure that requires brackets and other assembly connections, this application has the characteristics of convenient and quick assembly, while saving parts and enabling the device to be miniaturized.

[0055] Specifically, the snap-fit ​​structure 5 includes several sets of snap-fit ​​protrusions 51 and snap-fit ​​hook grooves 52 that can be adapted for snap-fit ​​connection. The snap-fit ​​protrusions 51 are protruding on the periphery of the boss portion 211, and the snap-fit ​​hook grooves 52 are formed on the sleeve portion 32. This design can achieve the purpose of quick installation and stable connection. Specifically, the snap-fit ​​structure can be provided with more than two sets of snap-fit ​​protrusions and snap-fit ​​hook groove assembly structures to achieve a more stable connection. In the specific embodiment of this application, four sets of connections are used, which makes assembly convenient and quick.

[0056] In a preferred embodiment of this application, the clutch 4 includes an output component 41, a clutch component 42, an iron component 43, and a magnetic bead 44. The output component 41 has a clutch cavity 410 on the side facing the gearbox 3, and the inner wall of the clutch cavity 410 has an inwardly recessed groove 411. The clutch component 42 is disposed in the clutch cavity 410 and is connected to the output end 30 of the gearbox 3, and there is a gap between the outer wall of the clutch component 42 and the inner wall of the clutch cavity 410. The iron component 43 is fixedly disposed on the upper side of the gearbox 3. The magnetic bead 44 is disposed in the clutch cavity 410, located on one side of the clutch component 42, and can be attracted to the iron component 43. The output end 30 of the gearbox 3 can drive the clutch component 42 to rotate until it contacts the magnetic bead 44, and drive the magnetic bead 44 to be inserted into the groove 411. Thus, when the magnetic bead 44 contacts the clutch component 42 and the groove 411 respectively, it indirectly drives the output component 41 to rotate. The working principle of the clutch is as follows: the movement of the magnetic bead 44 between the clutch component 42 and the output component 41 is used to connect or disconnect the power transmission. When the gearbox outputs power, the clutch component 42 drives the magnetic bead 44 to move to the groove 411, so that the clutch component 42 and the output component 41 are indirectly in contact through the magnetic bead 44, thereby realizing the transmission of power; when the gearbox has no power, the magnetic bead 44 is attracted to the iron part 43 under the magnetic attraction. When the magnetic bead 44 leaves the groove 411, the contact between the clutch component 42 and the output component 41 is broken, thereby disconnecting the power transmission.

[0057] In a preferred embodiment of this application, the clutch 42 includes an elliptical driving part 421 for contacting the magnetic bead 44. The distance between the short side of the elliptical driving part 421 and the clutch cavity 410 is greater than the outer diameter of the magnetic bead 44, and the distance between the long side of the elliptical driving part 421 and the clutch cavity 410 is less than the outer diameter of the magnetic bead 44. This design allows the magnetic bead 44 to leave the groove 411 without driving and to enter the groove 411 with driving.

[0058] In a preferred embodiment of this application, the output end 30 of the gearbox 3 is provided with two spaced-apart connecting protrusions 301, and a recessed connecting groove 302 is provided between the two connecting protrusions 301; the lower side of the drive unit 421 is integrally provided with a connecting insert 422 that can be fitted into the connecting groove 302, and two recessed connecting grooves 423 are provided on both sides of the connecting insert 422, and the two connecting grooves 423 can be fitted and nested with the two connecting protrusions 301 respectively. This design makes the connection more robust, stronger, and occupies less space.

[0059] Furthermore, the inner gear sleeve 31 has an output hole 301 on its upper side, and a gear ring 310 is provided on the inner wall of the inner gear sleeve 31. The gear ring 310 can be a helical gear ring or a spur gear ring. The gearbox 3 includes a first-stage planetary disk 33, a second-stage planetary disk 34, a first-stage sun gear 35, a second-stage sun gear 36, a first-stage planetary gear set 37, and a second-stage planetary gear set 38. The first-stage planetary disk 33 and the second-stage planetary disk 34 are sequentially arranged inside the inner gear sleeve 31. The first-stage planetary gear set 37 is rotatably arranged below the first-stage planetary disk 33 and is connected to the gear ring 301. The first-stage sun gear 35 is driven by the output shaft 22 of the brushless external rotor motor 2 and meshes with the first-stage planetary gear set 37; the second-stage planetary gear set 38 is rotatably disposed on the lower side of the second-stage planetary disk 34 and meshes with the gear ring 310; the second-stage sun gear 36 is fixedly disposed on the upper side of the first-stage planetary disk 33 and meshes with the second-stage planetary gear set 38; the output end 30 of the gearbox 3 is disposed on the upper side of the second-stage planetary disk 34 and extends through the output hole 301 and is driven by the clutch 4. The brushless external rotor motor 2 is responsible for providing rotational power, and the gearbox 3 is connected to the drive motor 2 to reduce the output speed of the motor and increase the torque to adapt to different working requirements, so as to form a stable power output and controllable speed.

[0060] In a specific application of this application, the brushless external rotor motor 2, gearbox 3 and clutch 4 connected by transmission are sequentially arranged in the curtain motor housing. The housing includes a bottom box housing with an upper opening and an end cover covering the upper end of the bottom box housing. The motor output port is located on the end cover.

[0061] In a specific embodiment of this application, a silicone pad 6 is provided at the bottom of the motor housing 21; it plays a role in shock absorption and buffering, making the structure more stable.

[0062] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A brushless external rotor motor characterized by: The brushless external rotor motor includes a motor housing, an output shaft hole at the upper end of the motor housing, a bearing and an inner stator fixedly disposed inside the motor housing, an output shaft rotatably disposed on the bearing, the upper end of the output shaft passing through the output shaft hole, an external rotor fixedly connected to the lower end of the output shaft, the motor housing covering the external rotor, and a gap between the periphery of the external rotor and the inner wall of the motor housing.

2. A brushless motor according to claim 1, wherein: The outer rotor includes an outer rotor body mounted on the lower end of the output shaft, and a magnet disposed on the inner wall of the outer rotor body, the magnet surrounding the inner stator.

3. A brushless motor according to claim 2, wherein: The outer rotor body is bowl-shaped, and the magnet is ring-shaped.

4. A brushless motor according to claim 1, wherein: The top of the motor housing is provided with a mounting tube extending from the output shaft hole toward the center inside, and the bearing and the inner stator are both mounted on the mounting tube.

5. A brushless motor according to claim 4, wherein: The bearings are installed on the inner sides of both the upper and lower ends of the mounting tube; and / or ​ The inner stator includes a stator core mounted on the outside of the mounting tube and multiple sets of coil windings wound on the stator core.

6. The brushless motor of claim 1, wherein: The motor housing is provided with a wire adapter plate that is electrically connected to the inner stator. The brushless external rotor motor also includes a motor wire that is electrically connected to the wire adapter plate at one end and passes through the motor housing and is electrically connected to an external power source at the other end.

7. A brushless motor according to any one of claims 1 to 6, wherein: The top of the motor housing has an upwardly protruding boss, which is used for assembly and connection with the gearbox.

8. A window treatment drive apparatus, characterized by: Includes the brushless external rotor motor according to claim 7, and a gearbox that is drively connected to the brushless external rotor motor; The gearbox includes an internal gear sleeve, and the bottom of the internal gear sleeve is provided with a sleeve portion that is sleeved around and assembled with the protrusion portion.

9. A curtain driving device according to claim 8, characterized in that: The sleeve portion and the boss portion are assembled and connected by a snap-fit ​​structure; The buckle structure includes several sets of buckle protrusions and buckle hook grooves that can be adapted for buckle connection. The buckle protrusions are provided on the periphery of the boss portion, and the buckle hook grooves are formed on the sleeve portion.

10. A curtain driving device according to claim 8, characterized in that: The inner toothed sleeve has an output hole on its upper side and a toothed ring on its inner wall. The gearbox includes a first-stage planetary disk, a second-stage planetary disk, a first-stage sun gear, a second-stage sun gear, a first-stage planetary gear set, and a second-stage planetary gear set, with the first-stage planetary disk and the second-stage planetary disk sequentially disposed within the inner gear sleeve; The first-stage planetary gear set is rotatably located on the lower side of the first-stage planetary disk and meshes with the gear ring. The first-stage sun gear is connected to the output shaft of the brushless external rotor motor and meshes with the first-stage planetary gear set. The secondary planetary gear set is rotatably disposed on the lower side of the secondary planetary disk and meshes with the gear ring. The secondary sun gear is fixedly disposed on the upper side of the primary planetary disk and meshes with the secondary planetary gear set. The output end of the gearbox is disposed on the upper side of the secondary planetary disk and extends out of the output hole.

11. A curtain driving device according to claim 8, characterized in that: It also includes a clutch that is connected to the transmission. The clutch includes: The output component has a clutch chamber on the side facing the gearbox, and the inner wall of the clutch chamber has an inwardly recessed groove; A clutch element is disposed in the clutch cavity and is connected to the output end of the gearbox, and there is a gap between the outer wall of the clutch element and the inner wall of the clutch cavity; An iron component is fixedly mounted on the upper side of the gearbox; A magnetic bead is disposed in the clutch cavity, located on one side of the clutch component, and can be attracted to the iron component; The output end of the gearbox can drive the clutch to rotate until it contacts the magnetic bead, and drive the magnetic bead to be engaged in the groove. Then, when the magnetic bead contacts the clutch and the groove respectively, it indirectly drives the output component to rotate.

12. A curtain driving device according to claim 11, characterized in that: The clutch includes an elliptical driving portion for contacting the magnetic bead. The distance between the short side of the driving portion and the clutch cavity is greater than the outer diameter of the magnetic bead, and the distance between the long side of the driving portion and the clutch cavity is less than the outer diameter of the magnetic bead; and / or The output end of the gearbox is provided with two connecting protrusions spaced apart, and a connecting groove recessed inward is provided between the two connecting protrusions. The clutch includes a drive part for contacting the magnetic bead. A connecting block that can be fitted and embedded in the connecting groove is integrally provided on the lower side of the drive part. Two connecting grooves recessed inward are provided on both sides of the connecting block. The two connecting grooves can be fitted and nested with the two connecting protrusions respectively.

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