Stepper motor and motor module

Abstract

The present invention provides a stepper motor and a motor module. The stepper motor comprises a housing, a rotating shaft rotatably connected to the housing, magnetic steel fixed to the rotating shaft, and a winding assembly accommodated on the inner side surface of the housing; the winding assembly surrounds and is spaced from the magnetic steel; the winding assembly comprises a ring-shaped frame coaxial with the housing, two claw poles arranged opposite to and spaced from each other in the axial direction of the rotating shaft, and a coil wound around the frame; the frame comprises a side wall around which the coil is wound, the side wall comprises arc-shaped portions having a first thickness and first planar portions having a second thickness, the second thickness is less than the first thickness, each first planar portion comprises an outer surface in contact with the coil, and the outer surface is a plane. The stepper motor in the present invention can solve the difficulty in molding caused by the reduction of local wall thickness of the frame, and can also further reduce the thickness dimension of the stepper motor in conjunction with corresponding design of other structures.

Description

Stepper motors and motor modules Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a stepper motor and motor module. Background Technology

[0002] Stepper motors have been widely used in most technical fields, such as electric motors, generators, and smart devices, due to their compact structure, high efficiency, and energy saving.

[0003] In related technologies, a stepper motor mainly includes a housing, a rotating shaft that is rotatably connected to the housing, a magnet fixed to the outer periphery of the rotating shaft, and a winding assembly sleeved on the rotating shaft and rotatably connected to the rotating shaft. The winding assembly is spaced around the outer side of the magnet. The winding assembly includes a plastic frame fixed to the inner side of the housing, two claw poles that are axially spaced around the rotating shaft, and a coil wound around the outer periphery of the plastic frame.

[0004] The trend towards thinner, lighter, and higher-performance smart devices demands stepper motors that provide the highest possible torque while minimizing thickness and size. However, in related technologies, the plastic frame of the stepper motor is easily limited by the molding wall thickness; that is, the molding wall thickness of the plastic frame must remain consistent, which prevents further reduction in the thickness of the stepper motor. Therefore, it is necessary to provide a stepper motor and motor module that are both thin and high-performance to solve the aforementioned technical problems. Technical issues

[0005] The purpose of this invention is to provide a new stepper motor and motor module to solve the problem in the related art where the frame of the stepper motor is limited by the molding wall thickness, which prevents the thickness of the stepper motor from being further reduced. Technical solutions

[0006] To achieve the above objectives, in a first aspect, the present invention provides a stepper motor, which includes a housing, a rotating shaft rotatably connected to the housing, a magnet fixed to the rotating shaft, and a winding assembly housed and fixed to the inner side of the housing, the winding assembly being spaced around the outer side of the magnet.

[0007] The winding assembly includes a ring-shaped frame coaxially arranged with the housing, two claw poles spaced apart from each other along the axial direction of the rotating shaft, and a coil wound around the outer periphery of the frame. Both claw poles extend into the frame and are spaced apart from each other from the magnet. The frame includes a sidewall around which the coil is wound. The sidewall includes an arcuate portion with a first thickness and a first planar portion with a second thickness, the second thickness being less than the first thickness. The first planar portion includes an outer surface that fits against the coil, and the outer surface is planar.

[0008] Preferably, the coil includes a first coil segment attached to the arc-shaped portion and a second coil segment attached to the first flat portion, wherein the first coil segment is arc-shaped and the second coil segment is flat.

[0009] Preferably, the skeleton further includes a hollow area penetrating the first planar portion, and the thickness of the first planar portion gradually decreases from the two ends connected to the arc-shaped portion toward the hollow area.

[0010] Preferably, the housing includes a second planar portion that is parallel to and opposite to the first planar portion; the claw pole includes a third planar portion that is parallel to and matches the second planar portion, and both the second planar portion and the third planar portion are flat.

[0011] Preferably, the frame further includes two annular enclosure portions formed by bending outwards from opposite ends of the sidewall along the axial direction of the rotating shaft, an extension portion protruding from one of the enclosure portions away from the sidewall, and two winding posts spaced apart from each other, formed by the extension portion protruding from the side of the enclosure portion away from the enclosure portion. The housing has a through hole, and the extension portion extends from the through hole to the outside of the housing. The enclosure portion includes a fourth planar portion that is parallel to and matches the second planar portion. The fourth planar portion is flat. The first planar portion is parallel to the extension direction of the winding posts, and the two ends of the coil are respectively wound around the two winding posts.

[0012] Preferably, each claw pole includes a ring-shaped fixing part fixed to the housing and a plurality of claws formed by bending and extending the inner periphery of the fixing part along the axial direction of the rotating shaft. The plurality of claws are spaced apart and all extend into the skeleton and are fixedly connected to the skeleton. The third planar part is provided in the fixing part; the claw of one claw pole is located between the two claws of another claw pole.

[0013] Preferably, the housing includes two cover plates fixed to both ends of the rotating shaft by a rotating bearing and a body portion fixedly connected to the two cover plates and forming an annular shape. The second planar portion is disposed on the body portion. The cover plates include a fifth planar portion that is parallel to and matches the second planar portion. The fifth planar portion is flat.

[0014] Preferably, the stepper motor includes at least two winding assemblies, which are stacked sequentially along the axial direction of the shaft.

[0015] Preferably, the skeleton includes two first planar portions, which are arranged radially opposite each other along the axis of rotation.

[0016] Secondly, the present invention provides a motor module, the motor module including a stepper motor as described above and a gearbox fixed to one end of the rotating shaft and rotatably connected to the rotating shaft; the gearbox includes a sixth flat portion that is parallel to and matches the second flat portion, the sixth flat portion being plate-shaped.

[0017] Preferably, the gearbox includes a hollow outer shell, a connecting bearing fixed to one end of the outer shell, a connecting part fixed in the connecting bearing, a gear set housed in the outer shell and meshing with the connecting part, and a shaft meshing with the gear set and extending out of the outer shell. The sixth planar portion is located on the side of the outer shell corresponding to the second planar portion, and a preset distance is provided between the gear set and the connecting bearing.

[0018] Preferably, the outer casing has a circular cross-section and includes a first connecting segment near the rotating shaft and a second connecting segment extending from the first connecting segment away from the rotating shaft. The outer diameter of the first connecting segment is larger than the outer diameter of the second connecting segment. The sixth planar portion is located on the side of the first connecting segment corresponding to the second planar portion, and the sixth planar portion and the outer side of the second connecting segment are on the same horizontal plane. The bearing is fixed to the first connecting segment, the gear set is housed in the second connecting segment, and the distance between the gear set and the first connecting segment is the preset distance. Beneficial effects

[0019] Compared with related technologies, the stepper motor in this invention designs the sidewall of the frame as an arc-shaped portion with a first thickness and a first flat portion with a second thickness, and limits the second thickness to be less than the first thickness. The first flat portion includes an outer surface that fits with the coil, and the outer surface is flat. This can effectively reduce the pressure of frame injection molding, thereby overcoming the situation where the frame is difficult to mold due to the local reduction in wall thickness, and ensuring the injection molding of the frame. At the same time, in conjunction with the corresponding design of other structures, the thickness of the stepper motor is further reduced, so as to achieve a significant reduction in the thickness of the stepper motor under the same torque, or to increase its torque by 15-25% under the same thickness of the stepper motor. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0021] Figure 1 is a three-dimensional structural diagram of the stepper motor provided in Embodiment 1 of the present invention;

[0022] Figure 2 is a partial exploded view of the stepper motor provided in Embodiment 1 of the present invention;

[0023] Figure 3 is a cross-sectional view along line AA in Figure 1;

[0024] Figure 4 is a cross-sectional view along line BB in Figure 1;

[0025] Figure 5 is a three-dimensional structural schematic diagram of the motor module provided in Embodiment 2 of the present invention;

[0026] Figure 6 is a partial structural exploded view of the motor module provided in Embodiment 2 of the present invention.

[0027] Among them: 100, stepper motor; 1, shaft; 2, magnet; 3, winding assembly; 31, frame; 311, side wall; 3111, arc-shaped part; 3112, first planar part; 31121, hollow area; 312, enclosure part; 3121, fourth planar part; 313, extension part; 314, winding post; 32, claw pole; 321, fixing part; 3211, third planar part; 322, pole claw; 33, coil; 331, first coil segment; 332, second coil segment; 4, housing; 41, cover plate; 411, fifth planar part; 42, rotating bearing; 43, body part; 431, second planar part; 44, through hole.

[0028] 200. Motor module; 5. Gearbox; 51. Housing; 511. First connecting section; 5111. Sixth flat section; 512. Second connecting section; 52. Connecting bearing; 53. Connecting part; 54. Gear set; 55. Shaft. Embodiments of the present invention

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] This invention provides a stepper motor 100, as shown in Figures 1 to 3. It includes a housing 4, a rotating shaft 1 rotatably connected to the housing 4, a magnet 2 fixed to the rotating shaft 1, and a winding assembly 3 that is housed and fixed to the inner side of the housing 4. The winding assembly 3 is spaced around the outer side of the magnet 2.

[0032] The winding assembly 3 includes a ring-shaped frame 31 coaxially arranged with the housing 4, two claw poles 32 spaced apart from each other along the axial direction of the shaft 1, and a coil 33 wound around the outer periphery of the frame 31. The two claw poles 32 extend into the frame 31 and are spaced apart from each other with the magnet 2.

[0033] The frame 31 includes a side wall 311 on which the coil is wound. The side wall 311 includes an arcuate portion 3111 with a first thickness and a first planar portion 3112 with a second thickness. The second thickness is less than the first thickness. The first planar portion 3112 includes an outer surface that fits against the coil 33. The outer surface is planar.

[0034] The coil 33 includes a first coil segment 331 attached to the arc-shaped portion 3111 and a second coil segment 332 attached to the first flat portion 3112. The first coil segment 331 is arc-shaped, and the second coil segment 332 is flat. By designing the second coil segment 332 attached to the first flat portion 3112 of the coil 33 to be flat, the thickness of the stepper motor 100 can be further reduced in accordance with the corresponding design of the other structures.

[0035] The skeleton 31 also includes a hollow area 31121 that penetrates the first planar portion 3112. The thickness of the first planar portion 3112 gradually decreases from both ends connected to the arc-shaped portion 3111 towards the hollow area 31121. Preferably, the hollow area 31121 is located in the middle of the first planar portion 3112, that is, the plastic in the thinnest central area of ​​the first planar portion 3112 is removed. This design ensures that the skeleton 31 does not have extremely thin walls, or allows for incomplete filling during molding, creating similar voids, thereby ensuring the feasibility of molding the skeleton 31.

[0036] Except for the first planar portion 3112, all other areas of the skeleton 31 are designed with the optimal wall thickness, that is, the arc portion 3111 is designed with the optimal wall thickness. This design is equivalent to designing the skeleton 31 with the optimal wall thickness, which can be formed with a thinner wall thickness that has sufficient strength, so as to ensure the compactness of the skeleton 31.

[0037] The housing 4 includes a second flat portion 431 that is parallel to and opposite to the first flat portion 3112, and the second flat portion 431 is flat. This design, in conjunction with the corresponding design of the other structures, can further reduce the thickness of the stepper motor 100.

[0038] The housing 4 includes two cover plates 41 fixed to both ends of the rotating shaft 1 by rotating bearings 42, and a body part 43 that is fixedly connected to the two cover plates 41 and is in an annular shape. A second flat part 431 is provided on the body part 43. This design enables a rotatable connection between the housing 4 and the rotating shaft 1.

[0039] The cover plate 41 includes a fifth flat portion 411 that is parallel to and matches the second flat portion 431. The fifth flat portion 411 is flat. This design can be coordinated with the corresponding design of the other structures to further reduce the thickness of the stepper motor 100.

[0040] The frame 31 also includes two annular enclosure portions 312 formed by bending outward from opposite ends of the sidewall 311 along the axial direction of the shaft 1, an extension portion 313 protruding from one of the enclosure portions 312 away from the sidewall 311, and two winding posts 314 formed by protruding from the extension portion 313 away from the enclosure portion 312 and spaced apart from each other. The housing 4 is provided with a through hole 44. The extension portion 313 extends from the through hole 44 to the outside of the housing 4. The enclosure portion 312 includes a fourth flat portion 3121 that is parallel to and matches the second flat portion 431. The fourth flat portion 3121 is flat. The first flat portion 3112 is parallel to the extension direction of the winding post 314. The two ends of the coil 33 are respectively wound on the two winding posts 314. The design of the winding post 314 facilitates the winding of the coil 33 at both ends, and the corresponding fourth plane part 3121 is provided on the enclosure part 312, which can be used in conjunction with the corresponding other structures to further reduce the thickness of the stepper motor 100.

[0041] The claw pole 32 includes a third flat portion 3211 that is parallel to and matches the second flat portion 431. The third flat portion 3211 is flat. The housing 4 is designed with a safety gap reserved between it and the coil 33. This design allows the claw pole 32 to adapt to the first flat portion 3112 and the second coil segment 332 of the coil 33, so that the stepper motor 100 can be configured with minimum space and equal gaps, thereby ensuring the compactness of the stepper motor 100, which is equivalent to further reducing the thickness of the stepper motor 100.

[0042] The claw pole 32 includes a ring-shaped fixing part 321 fixed to the housing 4 and a plurality of pole claws 322 formed by bending and extending the inner periphery of the fixing part 321 along the axial direction of the rotating shaft 1. The plurality of pole claws 322 are spaced apart and all extend into the frame 31 and are fixedly connected to the enclosure part 312 of the frame 31. A third planar part 3211 is provided on the fixing part 321. The pole claw 322 of one claw pole 32 is located between the two pole claws 322 of another claw pole 32.

[0043] The frame 31 includes two first planar portions 3112, which are arranged opposite each other radially along the axis of rotation 1; correspondingly, the second planar portion 431, the third planar portion 3211, the fourth planar portion 3121 and the fifth planar portion 411 each include two that are arranged opposite each other radially along the axis of rotation 1, and the first planar portion 3112, the second planar portion 431, the third planar portion 3211, the fourth planar portion 3121 and the fifth planar portion 411 on the same side are all on the same horizontal plane.

[0044] The winding assembly 3 can be designed as one or multiple. When multiple winding assemblies 3 are designed, the multiple winding assemblies 3 are stacked sequentially along the axial direction of the rotating shaft 1.

[0045] When there is only one winding assembly 3 and one main body 43, the two ends of the main body 43 are fixedly connected to the two cover plates 41 respectively. This is equivalent to the rotating shaft 1 being rotatably connected to the housing 4 through the cover plates 41 and the rotating bearing 42. At the same time, the two claw poles 32 in the winding assembly 3 are fixed to the two ends of the main body 43 respectively.

[0046] When there are multiple winding assemblies 3, the number of body parts 43 is the same as the number of winding assemblies 3. Multiple body parts 43 are fixedly connected in sequence. The two outermost body parts 43 are fixedly connected to the two cover plates 41 respectively. The corresponding rotating shaft 1 is rotatably connected to the housing 4 through the cover plate 41 and the rotating bearing 42. At the same time, the two claw poles 32 in each winding assembly 3 are fixed to the two ends of the corresponding body part 43 respectively. In addition, the first plane part 3112, the second plane part 431, the third plane part 3211, the fourth plane part 3121 and the fifth plane part 411 in each winding assembly 3 are all on the same horizontal plane. If there are two first plane parts 3112, the second plane part 431, the third plane part 3211, the fourth plane part 3121 and the fifth plane part 411 on the same side are on the same horizontal plane.

[0047] In this embodiment, the winding assembly 3 includes two windings stacked sequentially along the axial direction of the shaft 1, and correspondingly, the body portion 43 of the housing 4 also includes two windings.

[0048] Referring to Figure 4, let the center wall thickness of the first planar portion 3112 of the frame 31 be B, the wall thickness of the frame 31 excluding the first planar portion 3112 be A, and the overall thickness of the stepper motor 100 be H. In this case, the overall thickness of the stepper motor 100 is reduced by 2*(AB). Assuming A is 0.15mm and B is 0.05mm, for a conventional stepper motor with an original width (or overall outer diameter) of 5.2mm and an original length (including the extension and winding portion) of 8mm, the design of the stepper motor 100 in this embodiment can reduce the overall thickness of the conventional stepper motor by 2*(0.15-0.05) = 0.2mm, and its torque can be increased by 15-25%. Let the overall outer diameter of the stepper motor 100 be M, then M = H + 2*(AB). Furthermore, the case where M ≥ H + 2*(AB) also applies to the design of the stepper motor 100 in this embodiment.

[0049] Compared with related technologies, the stepper motor 100 of the present invention designs the sidewall 311 of the frame 31 as an arc-shaped portion 3111 with a first thickness and a first flat portion 3112 with a second thickness, and limits the second thickness to be less than the first thickness. The first flat portion 3112 includes an outer surface that fits against the coil 33 and the outer surface is flat. This can effectively reduce the pressure of injection molding of the frame 31, so as to overcome the situation where the local wall thickness of the frame 31 is reduced and its molding is difficult, and ensure the injection molding of the frame 31. At the same time, in conjunction with the corresponding design of other structures, the thickness of the stepper motor 100 is further reduced, so as to achieve a significant reduction in the thickness of the stepper motor 100 under the same torque, or to increase its torque by 15-25% under the same thickness of the stepper motor 100.

[0050] Example 2

[0051] This invention provides a motor module 200, as shown in Figures 5 and 6. It includes a stepper motor 100 as described in Embodiment 1 and a gearbox 5 fixed to one end of a rotating shaft 1 and rotatably connected to the shaft 1. The gearbox 5 includes a sixth flat surface 5111 parallel to and matched with the second flat surface 431. The sixth flat surface 5111 is flat. By introducing the gearbox 5 and designing the sixth flat surface 5111, the structure of the gearbox 5 can be matched with the first flat surface 3112, the second flat surface 431, the third flat surface 3211, the fourth flat surface 3121, and the fifth flat surface 411, thereby enabling the stepper motor 100 to achieve higher torque gain within the same width dimension.

[0052] The gearbox 5 includes a hollow outer shell 51, a connecting bearing 52 fixed to one end of the outer shell 51, a connecting part 53 fixed inside the connecting bearing 52, a gear set 54 housed inside the outer shell 51 and meshing with the connecting part 53, and a shaft 55 meshing with the gear set 54 and extending outside the outer shell 51. A sixth flat surface 5111 is located on the side of the outer shell 51 corresponding to the second flat surface 431. A preset distance (safety distance) is provided between the gear set 54 and the connecting bearing 52. This stepping design allows the gearbox 5 to better match the first flat surface 3112, the second flat surface 431, the third flat surface 3211, the fourth flat surface 3121, and the fifth flat surface 411, and also ensures the manufacturability of its parts and the processability of the finished product.

[0053] The outer casing 51 has a circular cross-section and includes a first connecting section 511 near the rotating shaft 1 and a second connecting section 512 extending from the first connecting section 511 away from the rotating shaft 1. The outer diameter of the first connecting section 511 is larger than that of the second connecting section 512. A sixth planar portion 5111 is provided on the side of the first connecting section 511 corresponding to the second planar portion 431. The outer side surfaces of the sixth planar portion 5111 and the second connecting section 512 are on the same horizontal plane. The bearing is fixed to the first connecting section 511, and the gear set 54 is housed in the second connecting section 512. The distance between the gear set 54 and the first connecting section 511 is a preset distance. This design allows the length of the sixth planar portion 5111 to meet the welding alignment requirements while maintaining a certain safe distance for the position of the gear set 54, thereby ensuring the optimal roundness of the second connecting section 512. In addition, the distance between the two sixth planar portions 5111 is equal to the outer diameter of the second connecting section 512, which also ensures that the gearbox 5 has the thinnest thickness.

[0054] When there are two second planar portions 431, there are also two sixth planar portions 5111. The distance between the two sixth planar portions 5111 is equal to the outer diameter of the second connecting segment 512, and the first planar portion 3112, the second planar portion 431, the third planar portion 3211, the fourth planar portion 3121, the fifth planar portion 411, and the sixth planar portion 5111 on the same side are all on the same horizontal plane.

[0055] Since the motor module 200 in this embodiment includes the stepper motor 100 in embodiment one, the motor module 200 in this embodiment can also achieve the technical effect achieved by the stepper motor 100 in embodiment one, which will not be elaborated here.

[0056] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements all fall within the protection scope of the present invention.

Claims

1. A stepper motor, comprising a housing, a rotating shaft rotatably connected to the housing, a magnet fixed to the rotating shaft, and a winding assembly housed and fixed to the inner side of the housing, the winding assembly being spaced around the outer side of the magnet; The winding assembly includes a ring-shaped frame coaxial with the housing, two claw poles spaced apart from each other along the axial direction of the shaft, and a coil wound around the outer periphery of the frame. Both claw poles extend into the frame and are spaced apart from each other from the magnet. The winding assembly is characterized in that... The frame includes a sidewall around which the coil is wound. The sidewall includes an arcuate portion with a first thickness and a first planar portion with a second thickness, the second thickness being less than the first thickness. The first planar portion includes an outer surface that fits against the coil, and the outer surface is planar.

2. The stepper motor as described in claim 1, characterized in that, The coil includes a first coil segment attached to the arc-shaped portion and a second coil segment attached to the first flat portion. The first coil segment is arc-shaped, and the second coil segment is flat.

3. The stepper motor as described in claim 1, characterized in that, The skeleton also includes a hollow area that runs through the first planar portion, and the thickness of the first planar portion gradually decreases from the two ends connected to the arc-shaped portion toward the hollow area.

4. The stepper motor as described in claim 1, characterized in that, The housing includes a second planar portion that is parallel to and opposite to the first planar portion; the claw pole includes a third planar portion that is parallel to and matches the second planar portion, and both the second planar portion and the third planar portion are flat.

5. The stepper motor as described in claim 4, characterized in that, The frame further includes two annular enclosure portions formed by bending outwards from opposite ends of the sidewall along the axial direction of the rotating shaft, an extension portion protruding from one of the enclosure portions away from the sidewall, and two winding posts spaced apart from each other, formed by the extension portion protruding from the side of the enclosure portion away from the enclosure portion. The housing has a through hole, and the extension portion extends from the through hole to the outside of the housing. The enclosure portion includes a fourth planar portion that is parallel to and matches the second planar portion. The fourth planar portion is flat. The first planar portion is parallel to the extension direction of the winding posts, and the two ends of the coil are respectively wound around the two winding posts.

6. The stepper motor as described in claim 4, characterized in that, Each claw pole includes a ring-shaped fixing part fixed to the housing and multiple claws formed by bending and extending the inner periphery of the fixing part along the axial direction of the rotating shaft. The multiple claws are spaced apart and extend into the skeleton and are fixedly connected to the skeleton. The third planar part is provided in the fixing part; the claw of one claw pole is located between the two claws of another claw pole.

7. The stepper motor as described in claim 4, characterized in that, The housing includes two cover plates fixed to both ends of the rotating shaft by a rotating bearing, and a body portion that is fixedly connected to the two cover plates and is in an annular shape. The second planar portion is disposed on the body portion. The cover plates include a fifth planar portion that is parallel to and matches the second planar portion. The fifth planar portion is flat.

8. The stepper motor as described in claim 1, characterized in that, The stepper motor includes at least two winding assemblies, which are stacked sequentially along the axial direction of the shaft.

9. The stepper motor as described in claim 1, characterized in that, The frame includes two first planar portions, which are arranged radially opposite each other along the axis of rotation.

10. A motor module, characterized in that, The motor module includes a stepper motor as described in claim 4 and a gearbox fixed to one end of the rotating shaft and rotatably connected to the rotating shaft; the gearbox includes a sixth flat portion that is parallel to and matches the second flat portion, the sixth flat portion being plate-shaped.

11. The motor module as described in claim 10, characterized in that, The gearbox includes a hollow outer shell, a connecting bearing fixed to one end of the outer shell, a connecting part fixed inside the connecting bearing, a gear set housed inside the outer shell and meshing with the connecting part, and a shaft meshing with the gear set and extending outside the outer shell. The sixth plane portion is located on the side of the outer shell corresponding to the second plane portion, and a preset distance is provided between the gear set and the connecting bearing.

12. The motor module as described in claim 11, characterized in that, The outer casing has a circular cross-section and includes a first connecting segment near the rotating shaft and a second connecting segment extending from the first connecting segment away from the rotating shaft. The outer diameter of the first connecting segment is larger than that of the second connecting segment. The sixth planar portion is located on the side of the first connecting segment corresponding to the second planar portion. The sixth planar portion and the outer side of the second connecting segment are on the same horizontal plane. The bearing is fixed to the first connecting segment, and the gear set is housed in the second connecting segment. The distance between the gear set and the first connecting segment is the preset distance.

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