Self-locking motor

Abstract

The self-locking motor comprises a motor body and a driving shaft, the driving shaft is sleeved with a friction ring in interference fit with the driving shaft, the friction ring is provided with an opening and provided with a limiting part, the limiting part is in limiting fit with the motor body through an elastic piece, and the friction ring provides braking force for limiting rotation of the driving shaft. According to the self-locking motor, the friction ring is not easy to wear, the service life is long, the self-locking stability is good, and the universality is good.

Description

Technical Field

[0001] This application relates to the field of drive motor technology, specifically a self-locking motor. Background Technology

[0002] Current electric furniture, such as electric sofas, electric lifting platforms, and electric folding beds, are all equipped with linear drive devices. This linear drive device, also known as a linear actuator, is used to convert the kinetic energy of the rotational motion of the drive motor into linear power. Its structure includes a drive motor and a linear push rod that is connected to the drive motor for transmission.

[0003] To prevent electric furniture from passively descending under heavy external loads, or to ensure that electric furniture remains stably in a specific posture, the drive shaft of the linear drive motor is generally equipped with a braking device or a self-locking device. This braking device or self-locking device generates a self-locking force when the drive shaft of the motor passively rotates, thereby hindering or limiting the passive rotation of the drive shaft and ensuring the stability of the electric furniture. For example, Chinese patent application CN215861421U, entitled "Motor and Linear Actuator with Self-Locking Function," describes a friction ring mounted on the drive shaft of the motor. This friction ring has a notch and a limiting part. The motor's end cover cooperates with the limiting part for limiting. Specifically, the end cover has a groove-shaped locking part, and the limiting part of the friction ring is circumferentially limited within the locking part, so that the friction ring grips the drive shaft when the drive shaft rotates in a first direction, achieving self-locking or braking of the drive shaft.

[0004] The self-locking motors or motors mentioned above generally have the following defects in actual use: because the limiting part on the friction ring and the grooved locking part on the end cover are rigidly abutting and limiting, the friction ring is easily worn and fails during the process of the friction ring clamping the drive shaft to provide rotational resistance to the drive shaft or to stop the drive shaft from rotating, resulting in a decrease in self-locking force and poor self-locking stability; in addition, the friction force of the friction ring on the drive shaft is not adjustable, resulting in poor versatility. Utility Model Content

[0005] The technical problem to be solved by this application is to overcome the defects of the above-mentioned related technologies and provide a self-locking motor that makes the friction ring less prone to wear, has a long service life, good self-locking stability, and good versatility.

[0006] The technical solution of this application is to provide a self-locking motor with the following structure: including a motor body and a drive shaft, a friction ring that is interference-fitted with the drive shaft is sleeved on the drive shaft, the friction ring has an opening and a limiting part is provided on the friction ring, the limiting part is limited to the motor body through an elastic element, and the friction ring provides a braking force to limit the rotation of the drive shaft.

[0007] In some embodiments, the elastic element is a compression spring, and the elastic element causes the friction ring to always have a tendency to grip the drive shaft.

[0008] In some embodiments, there are two limiting parts, which are respectively disposed on both sides of the opening. The motor body is provided with a limiting groove, and the two limiting parts are respectively disposed in the limiting groove. One end of the elastic member abuts against the inner wall of the limiting groove, and the other end abuts against one of the limiting parts. The two limiting parts are circumferentially limited in the limiting groove.

[0009] In some embodiments, both free ends of the friction ring protrude outward from the outer peripheral wall of the friction ring and form two limiting portions. The two limiting portions include a first limiting portion and a second limiting portion. The second limiting portion abuts against the inner wall of the limiting groove. One end of the elastic member abuts against the inner wall of the limiting groove, and the other end abuts against the first limiting portion.

[0010] In some embodiments, the first limiting portion and the second limiting portion are arranged in parallel, and the length of the first limiting portion is greater than the length of the second limiting portion, and the elastic element is connected to the end of the first limiting portion or near the end.

[0011] In some embodiments, the friction ring has a plurality of oil reservoirs on its inner circumferential wall.

[0012] In some embodiments, the oil reservoir extends axially along the friction ring and is distributed circumferentially along the friction ring.

[0013] In some embodiments, the outer circumferential wall of the friction ring is provided with at least one deformable portion along the circumferential direction.

[0014] In some embodiments, the deformable portion includes a plurality of grooves spaced apart circumferentially along the friction ring and extending axially along the friction ring; or the deformable portion includes at least one recessed portion extending along the length of the outer circumferential wall of the friction ring and being concave.

[0015] In some embodiments, one end of the motor body is provided with an end cover through which the drive shaft passes, and the limiting groove is provided on the end cover.

[0016] In summary, compared with related technologies, the self-locking motor of this application has the following advantages: the limiting part of the friction ring of the self-locking motor is limited and cooperated with the motor body through an elastic element. When the drive shaft rotates, the friction between the drive shaft and the friction ring causes the friction ring to grip the drive shaft to provide braking force to limit the rotation of the drive shaft, thereby improving the control accuracy of the motor and enabling the motor to have self-locking capability. Furthermore, under the action of this friction force, the torque applied to the friction ring by the drive shaft causes the limiting part of the friction ring to compress or stretch the elastic element to obtain a certain elastic movement space, thereby automatically adjusting the gripping force or pressing force of the friction ring on the drive shaft to prevent or delay the wear and failure of the friction ring, resulting in a long service life and good self-locking stability. In addition, by replacing the elastic element with different stiffness coefficients or elastic forces, the gripping force or pressing force of the friction ring on the drive shaft when the drive shaft rotates can be adjusted, making the self-locking capability of the self-locking motor adjustable and versatile. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a self-locking motor according to some embodiments of this application.

[0018] Figure 2 This is a cross-sectional structural schematic diagram of a self-locking motor according to some embodiments of this application.

[0019] Figure 3 This is a schematic diagram of the assembly structure of a self-locking motor according to some embodiments of this application.

[0020] Figure 4 This is a schematic diagram of another angle assembly structure of a self-locking motor according to some embodiments of this application.

[0021] Figure 5 This is a schematic diagram of the structure of a friction ring for a self-locking motor according to some embodiments of this application.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Motor body; 100. End cover; 101. Limiting groove; 2. Drive shaft; 3. Friction ring; 300. First limiting part; 301. Second limiting part; 302. Oil reservoir; 303. Groove; 304. Positioning post; 4. Elastic element. Detailed Implementation

[0024] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0025] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0026] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0027] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] See Figures 1-5 As shown, this application discloses a self-locking motor, also known as a self-locking motor, which is used as a power source in the linear drive device of electric furniture. In this embodiment, the self-locking motor includes a motor body 1 and a drive shaft 2 connected to the center of the motor body 1. The motor body 1 drives the drive shaft 2 to rotate to output power.

[0029] Further in this embodiment, see Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, a self-locking device or braking device is installed on the drive shaft 2 of the self-locking motor. Specifically, the self-locking device or braking device includes a friction ring 3 that is sleeved on the drive shaft 2 and has an interference fit with the drive shaft 2. The inner circumferential wall of the friction ring 3 is pressed against the drive shaft 2, and the friction ring 3 has an opening that disconnects the friction ring 3. The friction ring 3 is provided with a limiting part that is in a limiting fit with the motor body 1 so that the friction ring 3 does not rotate with the drive shaft 2. When the drive shaft 2 rotates, the friction ring 3 provides a braking force to limit the rotation of the drive shaft 2.

[0030] It is understandable that the friction ring 3 is sleeved on the drive shaft 2 and is interference-fitted with the drive shaft 2. There is a certain clamping force or preload between the friction ring 3 and the drive shaft 2. The circumferential rotation of the friction ring 3 is limited by the motor body 1. During the rotation of the drive shaft 2, the friction force between the friction ring 3 and the drive shaft 2 always exerts resistance to the rotation of the drive shaft 2. In particular, the friction ring 3 has an opening, and the friction ring 3 forms two free ends at the opening. When the drive shaft 2 rotates, the friction force between the drive shaft 2 and the friction ring 3 will cause the two free ends of the friction ring 3 to move closer to each other or have a tendency to move closer to each other, thereby reducing the width of the opening so that the friction ring 3 can hug the drive shaft 2. In other words, when the drive shaft 2 rotates, the resistance of the friction ring 3 to the drive shaft 2 is greater than the resistance of the friction ring 3 to the drive shaft 2 when the drive shaft 2 is stationary. During the rotation of the drive shaft 2, the friction ring 3 can always apply friction or resistance to the drive shaft 2 so that the drive shaft 2 can stop rotating more quickly and improve the motor control accuracy. When the drive shaft 2 is stationary, the friction applied by the friction ring 3 to the drive shaft 2 gives the drive shaft 2 a self-locking ability, ensuring the stability of the electric furniture.

[0031] It is easy to understand that during the circumferential limiting of the friction ring 3 and the rotation of the drive shaft 2, the interference fit between the friction ring 3 and the drive shaft 2 inevitably leads to wear of the friction ring 3. In particular, when the drive shaft 2 rotates, the friction between the drive shaft 2 and the friction ring 3 causes the friction ring 3 to grip the drive shaft 2 more and more tightly. At this time, the clamping force applied by the friction ring 3 to the drive shaft 2 increases, and the friction ring 3 will wear more severely. In this embodiment, see Figure 2 As described above, an elastic element 4 is provided between the limiting part of the friction ring 3 and the motor body 1, so that the limiting part of the friction ring 3 is circumferentially limited and engaged with the motor body 1 through the elastic element 4. In this way, when the drive shaft 2 rotates, the friction force between the drive shaft 2 and the friction ring 3 not only provides a braking force to limit the rotation of the drive shaft 2, but also, under the action of this friction force, the torque applied by the drive shaft 2 to the friction ring 3 causes the limiting part of the friction ring 3 to compress or stretch the elastic element 4 to obtain a certain elastic movement space, thereby automatically adjusting the clamping force or pressing force of the friction ring 3 on the drive shaft 2, so as to prevent or delay the wear of the friction ring 3, so that the service life of the friction ring 3 is long and the self-locking stability is good.

[0032] It is understandable that the limiting part is set on the friction ring 3, and it cooperates with the motor body 1 to limit the circumferential rotation of the friction ring 3. Therefore, the number of the limiting part can be one, two or three, etc., and the setting position of the limiting part on the friction ring 3 is not specifically limited, as long as it is connected to the outer circumference of the friction ring 3.

[0033] To make the mounting structure of the friction ring 3 more compact and the connection more stable; further, in this embodiment, see... Figure 2 and Figure 5 As shown, the friction ring 3 has two limiting parts, which are respectively set on both sides of the opening of the friction ring 3. The motor body 1 is provided with a limiting groove 101, and the two limiting parts are respectively set in the limiting groove 101. One end of the elastic member 4 abuts against the inner wall of the limiting groove 101, and the other end abuts against one of the limiting parts. The two limiting parts are circumferentially limited in the limiting groove 101.

[0034] For example, see Figure 2 As shown, the friction ring 3 is C-shaped and is fitted onto the drive shaft 2 with an interference fit. Both free ends of the friction ring 3 protrude outwards from the outer peripheral wall of the friction ring 3, forming two limiting portions. These two limiting portions include a first limiting portion 300 and a second limiting portion 301. The first limiting portion 300 and the second limiting portion 301 extend outwards roughly along the radial direction of the friction ring 3 relative to the friction ring 3. The second limiting portion 301 abuts against one of the inner walls of the limiting groove 101. An elastic member 4 is disposed outside the first limiting portion 300, with one end abutting against the inner wall of the limiting groove 101 and the other end abutting against the first limiting portion 300. In this embodiment, both free ends of the friction ring 3 protrude outwards to form two limiting portions, meaning the limiting portions and the friction ring 3 are integrally formed, resulting in a simple structure and convenient processing.

[0035] In the example above, see Figure 2 As shown, it can be foreseen that when the drive shaft 2 rotates clockwise, the second limiting part 301 abuts against the inner wall of the limiting groove 101, limiting the drive shaft 2. The frictional force applied to the friction ring 3 by the drive shaft 2 forces the first limiting part 300 to move closer to the second limiting part 301 or causes the first limiting part 300 to have a tendency to move closer to the second limiting part 301, thereby causing the friction ring 3 to further tighten or press the drive shaft 2, providing resistance or braking force to restrict the rotation of the drive shaft 2. When the drive shaft 2 rotates counterclockwise, the first limiting part 300 abuts against the elastic member 4, limiting the drive shaft 2. The frictional force applied to the friction ring 3 by the drive shaft 2 forces the second limiting part 301 to move closer to the first limiting part 300 or causes the second limiting part 301 to have a tendency to move closer to the first limiting part 300. The friction ring 3 clamps or presses against the drive shaft 2, providing resistance or braking force to limit the rotation of the drive shaft 2. In this state, the torque applied by the drive shaft 2 to the friction ring 3 will cause the first limiting part 300 of the friction ring 3 to compress the elastic element 4 or cause the first limiting part 300 of the friction ring 3 to have a tendency to compress the elastic element 4. The elastic force of the elastic element 4 gives the first limiting part 300 of the friction ring 3 a certain elastic movement space. When this elastic movement space exists, the clamping force of the friction ring 3 pressing against the drive shaft 2 can be continuously adjusted and balanced by itself, so that the clamping force between the friction ring 3 and the drive shaft 2 is kept within a certain range. This effectively avoids the friction ring 3 applying too much clamping force to the drive shaft 2 and thus wearing failure.

[0036] It is understood that, in the above embodiment, see Figure 2 As shown, because one end of the elastic element 4 abuts against the inner wall of the limiting groove 101 and the other end abuts against the first limiting part 300; when the drive shaft 2 rotates clockwise, the friction ring 3 clamps or presses the drive shaft 2 to provide a braking force that restricts the rotation of the drive shaft 2, which is slightly greater than the braking force provided by the friction ring 3 to restrict the rotation of the drive shaft 2 when the drive shaft 2 rotates counterclockwise; that is, the braking force provided by the friction ring 3 to the drive shaft 2 is different when the drive shaft 2 rotates forward and reverse. Therefore, in the actual application of this self-locking motor, during the process of the motor driving the linear drive mechanism to unfold and raise the electric furniture, such as Figure 2 When the drive shaft 2 rotates counterclockwise, the friction ring 3 exerts less resistance on the drive shaft 2, thus avoiding energy loss in the self-locking motor. Conversely, during the process of the motor driving the linear drive mechanism to retract and lower the electric furniture to stop, such as... Figure 2 In the middle, the drive shaft 2 rotates clockwise. At this time, the friction ring 3 has a large resistance to the rotation of the drive shaft 2, which helps to stop the machine quickly and maintain the self-locking force of the drive shaft 2 in a stationary state.

[0037] In the above embodiment, because the friction ring 3 and the drive shaft 2 are configured with an interference fit, the friction ring 3 grips the drive shaft 2, providing resistance to the rotation of the drive shaft 2. Furthermore, in this embodiment, to increase the gripping force of the friction ring 3 on the drive shaft 2, the elastic element 4 is a cylindrical compression spring, and the elastic element 4 ensures that the friction ring 3 always has a tendency to grip the drive shaft 2. That is, the elastic element 4 applies a certain elastic force to the friction ring 3, causing the friction ring 3 to further grip the drive shaft 2, thereby increasing the pressure or clamping force applied by the friction ring 3 on the drive shaft 2, increasing the friction between the friction ring 3 and the drive shaft 2, increasing the braking force provided by the friction ring 3 to restrict the rotation of the drive shaft 2, enabling the drive shaft 2 to brake quickly, and improving the self-locking capability of the self-locking motor.

[0038] Further in this embodiment, see Figure 2As shown, the first limiting part 300 and the second limiting part 301 are arranged in parallel. The outer side wall of the first limiting part 300 is provided with a protruding positioning post 304. One end of the elastic member 4 is connected to the positioning post 304, and the other end abuts against the inner wall of the limiting groove 101. The length of the first limiting part 300 is greater than the length of the second limiting part 301, and the elastic member 4 is connected to the end of the first limiting part 300 or near the end. It can be understood that when the drive shaft 2 is stationary, because the elastic member 4 is located at a position away from the friction ring 3 in the first limiting part 300, and the second limiting part 301 is limited by the limiting groove 101, the lever arm of the force applied by the elastic member 4 to the first limiting part 300 increases. When the elastic force of the elastic member 4 is applied to the first limiting part 300, the first limiting part 300 is more likely to move closer to the second limiting part 301 or the first limiting part 300 is more likely to have a tendency to move towards the second limiting part 301. This makes it easier for the friction ring 3 to grip the drive shaft 2, so that the friction ring 3 can apply a greater braking force to the drive shaft 2.

[0039] Furthermore, in the aforementioned embodiment, the length of the second limiting part 301 is less than the length of the first limiting part 300, thereby making installation more convenient and saving material costs.

[0040] In other embodiments, the length of the first limiting part 300 and the length of the second limiting part 301 can be set to be equal, as long as the second limiting part 301 can abut against the inner wall of the limiting groove 101 and the first limiting part 300 is limited by the elastic member 4 against the inner wall of the limiting groove 101.

[0041] To further facilitate the gripping of the friction ring 3 on the drive shaft 2 and provide resistance to the rotation of the drive shaft 2; see [link to relevant documentation]. Figure 2 and Figure 5 As shown, the outer circumferential wall of the friction ring 3 has a deformable section along its circumference, which is located on the side of the friction ring 3 opposite to the opening. This deformable section allows the friction ring 3 to deform under the action of external force to grip the drive shaft 2. Specifically, the deformable section includes multiple grooves 303 that are spaced apart along the circumference of the friction ring 3 and extend along the axial direction of the friction ring 3. The grooves 303 on the deformable section improve the deformability of the friction ring 3, making it easier for the friction ring 3 to deform under the action of external force to grip the drive shaft 2.

[0042] In some embodiments, the deformable portion may also include at least one recessed portion extending along the length of the outer circumferential wall of the friction ring and being concave, such as an arcuate groove extending along the length of the outer circumferential wall of the friction ring.

[0043] In some embodiments, in order to make the friction ring 3 more easily deformed under the action of external force to grip the drive shaft 2, the deformation part can also be set to two or three sections, etc., which can be set according to actual needs.

[0044] It is understood that in the above embodiments, the friction ring 3 can be a metal part or a plastic part, which has good wear resistance and elastic deformation capability.

[0045] To further prevent wear on the friction ring 3 and improve its service life, in this embodiment, multiple oil reservoirs 302 are provided on the inner circumferential wall of the friction ring 3. See details... Figure 2 and Figure 5 As shown, the oil reservoir 302 extends along the axial direction of the friction ring 3 and is distributed along the circumference of the friction ring 3. Lubricating grease is added to the oil reservoir 302. When the self-locking motor is working, the speed of the drive shaft 2 is relatively high. The lubricating grease is driven and forms a lubricating oil film between the friction ring 3 and the drive shaft 2 under the action of centrifugal force. At this time, the resistance of the friction ring 3 to the motor drive shaft 2 is relatively small, which avoids the loss of motor power and makes the friction ring 3 less prone to wear. When the drive shaft 2 of the self-locking motor is braking or stationary, the lubricating grease is pressed into the oil reservoir 302 by the pressure of the friction ring 3. At this time, the resistance of the friction ring 3 to the drive shaft 2 increases to achieve braking or self-locking.

[0046] Furthermore, in this embodiment, the oil storage groove 302 on the inner circumferential wall of the friction ring 3 and the groove 303 in the deformation area of ​​the friction ring 3 are staggered in the thickness direction of the friction ring 3 so that the wall thickness of the friction ring 3 is uniform, thereby improving the wear resistance and service life of the friction ring 3.

[0047] In this embodiment, an end cover 100 for the drive shaft 2 to pass through is connected to one end of the motor body 1 near the power output end of the drive shaft 2. A limiting groove 101 is provided on the end cover 100, that is, the friction ring 3 of the self-locking device or braking device is provided on the side of the drive shaft 2 near its power output end; in other embodiments, the friction ring 3 of the self-locking device or braking device can also be provided at the tail end or middle of the drive shaft 2.

[0048] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0049] In the description of this application, the references to terms such as "an embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0050] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A self-locking motor, characterized in that: The device includes a motor body and a drive shaft. A friction ring, which is interference-fitted with the drive shaft, is sleeved on the drive shaft. The friction ring has an opening and a limiting part is provided on the friction ring. The limiting part is limited to the motor body through an elastic element. The friction ring provides a braking force to restrict the rotation of the drive shaft.

2. The self-locking motor according to claim 1, characterized in that: The elastic element is a compression spring, and the elastic element ensures that the friction ring always has a tendency to grip the drive shaft.

3. The self-locking motor according to claim 2, characterized in that: The limiting part is two and is respectively disposed on both sides of the opening. The motor body is provided with a limiting groove, and the two limiting parts are respectively disposed in the limiting groove. One end of the elastic member abuts against the inner wall of the limiting groove, and the other end abuts against one of the limiting parts. The two limiting parts are circumferentially limited in the limiting groove.

4. The self-locking motor according to claim 3, characterized in that: Both free ends of the friction ring protrude outward from the outer peripheral wall of the friction ring and form two limiting portions. The two limiting portions include a first limiting portion and a second limiting portion. The second limiting portion abuts against the inner wall of the limiting groove. One end of the elastic member abuts against the inner wall of the limiting groove, and the other end abuts against the first limiting portion.

5. The self-locking motor according to claim 4, characterized in that: The first limiting part and the second limiting part are arranged in parallel, and the length of the first limiting part is greater than the length of the second limiting part. The elastic element is connected to the end of the first limiting part or near the end.

6. The self-locking motor according to any one of claims 1 to 5, characterized in that: The friction ring has multiple oil storage grooves on its inner circumferential wall.

7. The self-locking motor according to claim 6, characterized in that: The oil storage tank extends along the axial direction of the friction ring and is distributed along the circumference of the friction ring.

8. The self-locking motor according to any one of claims 1 to 5, characterized in that: The outer circumferential wall of the friction ring is provided with at least one deformable section along the circumferential direction.

9. The self-locking motor according to claim 8, characterized in that: The deformable portion includes a plurality of grooves spaced apart circumferentially along the friction ring and extending axially along the friction ring; or the deformable portion includes at least one recessed portion extending along the length of the outer circumferential wall of the friction ring and being concave.

10. The self-locking motor according to claim 3, characterized in that: One end of the motor body is provided with an end cover through which the drive shaft passes, and the limiting groove is provided on the end cover.

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