Composite structure outer rotor brushless motor and electric clipper

Abstract

The application discloses a composite structure outer rotor brushless motor which comprises a central shaft, a support assembly, a stator assembly and a rotor assembly, the support assembly comprises an upper support and a lower support which are assembled and connected with each other, the upper support and the lower support are sleeved on the central shaft and are rotationally connected with the central shaft, the rotor assembly is rotatably supported on the central shaft through a bearing set, wherein the support assembly partially wraps and supports the rotor assembly from the periphery of the rotor assembly, so that the whole motor is in the installation form of an inner rotor motor. The composite structure of "outer rotor inner core + inner rotor outer shape" is adopted, the rotor assembly is arranged on the inner side and is in the form of an outer rotor, high torque density and high rotational inertia are guaranteed, the semi-closed support structure provides excellent protection while retaining necessary ventilation openings, so that the motor can still be effectively cooled in a closed environment, and the protection level and the heat dissipation performance are balanced.

Description

Technical Field

[0001] This invention relates to the field of electric clipper motor technology, and in particular to a composite structure external rotor brushless motor and electric clipper. Background Technology

[0002] Brushless DC motors can be divided into two main categories based on the relative position of the rotor and the stator: external rotor brushless motors and internal rotor brushless motors. Each has its own structural advantages, but each also has inherent shortcomings that are difficult to overcome in its respective application scenarios.

[0003] External rotor brushless motors have their rotor core and permanent magnets located on the outside of the stator, offering advantages such as high rotational inertia and high torque density, making them widely used in applications requiring low-speed, high-torque direct drive. However, traditional electric clippers using external rotor motors typically expose the rotor core and magnets directly, encased only in a thin-walled shell, which has the following drawbacks: First, it has poor dynamic stability. The rotor mass is concentrated on the outer edge, and it is prone to radial deformation and dynamic imbalance vibration due to centrifugal force when rotating at high speed. At the same time, the concentricity between the rotor and the stator is highly dependent on the machining accuracy of the bearings and supports. After long-term operation, bearing wear can easily lead to radial runout, which in turn causes periodic vibration and affects the output quality.

[0004] Second, the protection level is low. The rotor housing is directly exposed to the external environment and lacks airtight protection: on the one hand, foreign objects (tools, people, etc.) can easily come into contact with the rotating housing, which can easily cause the rotor to stall or the windings to be damaged; on the other hand, under collision or drop conditions, the thin-walled housing is prone to plastic deformation, which can lead to uneven air gap between the rotor and the stator or even direct rubbing, causing increased vibration, sudden drop in torque or motor jamming. Moreover, it is difficult to repair after deformation, resulting in a high scrap rate of the whole machine.

[0005] Third, poor installation compatibility. The rotating housing makes it difficult to connect compactly with other equipment, restricts the layout of lead wires and output shafts, and requires additional design of transition installation structures during system integration, increasing the overall size and assembly complexity.

[0006] The rotor of an internal rotor brushless motor is located inside the stator, offering advantages such as fast dynamic response, ease of achieving high protection levels, and strong installation compatibility. However, due to its small rotor radius and short lever arm, traditional electric shears using internal rotor motors suffer from the following shortcomings in low-speed, high-torque direct-drive scenarios: First, the torque is lower for the same volume, making it prone to hair jamming and causing pain for the user, resulting in a poor user experience. The rotor of an internal rotor motor is located inside the stator, resulting in a smaller radius of electromagnetic force application. Therefore, under the same volume and power conditions, the output torque is far lower than that of an external rotor motor. To obtain higher torque, a speed reducer is usually required, which not only increases the system's size, weight, and cost, but also introduces transmission losses and additional potential points of failure.

[0007] Secondly, low-speed, high-torque applications require additional transmission mechanisms. Unlike external rotor motors, internal rotor motors cannot directly output low-speed, high-torque outputs and must rely on transmission devices such as planetary reducers or harmonic reducers, which complicates the system structure and leads to issues such as backlash, noise, and maintenance.

[0008] Third, heat dissipation is a prominent issue. Although the stator coils of an internal rotor motor are close to the outer casing, which is beneficial for heat dissipation, when the motor and reducer are integrated and enclosed in a small space, the high temperature generated by braking or long-term heavy load can easily accumulate inside and be conducted to the permanent magnet area, affecting the performance of the permanent magnet and, in severe cases, causing irreversible demagnetization.

[0009] Fourth, the winding process is complex. The stator coils of an internal rotor motor need to be wound from the inside onto the stator teeth. The winding space is narrow, which requires high precision from automated winding equipment. This results in slow production cycle, large equipment investment, and problems such as inter-turn short circuits or insufficient slot fill factor, affecting the consistency of motor performance.

[0010] In summary, existing external rotor motors and internal rotor motors each have their own structural advantages, but also inherent drawbacks that are difficult to overcome: external rotor motors, while having high torque density, suffer from poor stability, weak protection, and inconvenient installation; internal rotor motors, while offering good protection and easy installation, have low torque density, require external transmission, and face difficulties in cooling and winding. Therefore, there is an urgent need for a new motor structure that combines the high torque density of external rotor motors with the high protection level and installation compatibility of internal rotor motors, in order to solve the problems of insufficient dynamic stability, low protection level, and poor installation adaptability caused by unreasonable structural layout in existing technologies. Summary of the Invention

[0011] Based on this, it is necessary to provide a composite structure external rotor brushless motor and electric clipper to address the problems of existing technology. The composite structure of "external rotor core + inner rotor shape" is adopted, and the rotor assembly is located on the inner side in the form of an external rotor, which ensures high torque density and high rotational inertia.

[0012] To address the problems of existing technologies, this invention discloses a composite structure external rotor brushless motor, comprising: Central axis; A support assembly includes an upper support and a lower support that are assembled and connected to each other. The upper support and the lower support are sleeved on the central shaft and rotatably connected to the central shaft. The lower support includes a base and a support cylinder disposed on the base. A stator assembly, fixed to the supporting cylinder, includes a stator core and windings disposed on the stator core, wherein the supporting cylinder is interference-fitted with the inner wall of the stator core; The rotor assembly is cylindrically sleeved outside the stator assembly, including a housing and a magnet disposed on the inner side wall of the housing. The rotor assembly is rotatably supported on the central shaft by a bearing assembly. The bracket assembly partially wraps around and supports the rotor assembly from the outside, so that the motor as a whole is installed in the form of an inner rotor motor.

[0013] In one embodiment, the bearing assembly includes a first bearing and a second bearing respectively disposed at both axial ends of the rotor assembly. The first bearing and the second bearing are both sleeved on the central shaft, and the axial distance between the first bearing and the second bearing is not less than 0.75 times the axial length of the rotor assembly.

[0014] In one embodiment, the outer ring of the first bearing is fixedly connected to the upper bracket, and the inner ring of the first bearing is clearance-fitted with the central shaft; the outer ring of the second bearing is fixedly connected to the lower bracket, and the inner ring of the second bearing is clearance-fitted with the central shaft; the outer circumferential surface of the central shaft is provided with knurled texture.

[0015] In one embodiment, the rotor assembly further includes a copper sleeve, which is connected to the housing by riveting. The copper sleeve includes an integrally formed annular portion, a flip-up portion, and a straight cylindrical portion. The straight cylindrical portion is vertically disposed on the annular portion, and the flip-up portion is disposed on the annular portion and close to the straight cylindrical portion.

[0016] In one embodiment, the assembly connection between the upper bracket and the lower bracket is achieved by any one of screw fixing, riveting fixing, or rotary plug fixing.

[0017] In one embodiment, when riveting is used for fixing, the lower bracket has protruding edges on both sides, and the outer end of the upper bracket has a notch that matches the protruding edges; when rotating and inserting is used for fixing, the bottom outer side of the upper bracket has a receiving groove, and the top inner side of the lower bracket has a retaining strip, which matches and engages with the receiving groove.

[0018] In one embodiment, the upper support has a U-shaped structure, and a bearing boss protrudes from the top of the upper support. The bearing boss has a first receiving cavity inside, and the first bearing is matched and received in the first receiving cavity. The base of the lower support has a second receiving cavity in the middle, and the second receiving cavity is axially connected to the internal space of the supporting cylinder. The second bearing is matched and received in the second receiving cavity.

[0019] In one embodiment, the height of the supporting cylinder is not less than 3 / 4 of the height of the stator core, so that at least most of the stator core is supported by the supporting cylinder.

[0020] In one embodiment, the support assembly is a semi-enclosed structure that covers the main exposed area of ​​the rotor assembly while retaining axial or radial ventilation openings to balance the protection level and heat dissipation requirements.

[0021] The present invention also discloses an electric clipper comprising the above-described composite structure external rotor brushless motor.

[0022] In summary, the aforementioned composite external rotor brushless motor includes a central shaft, a support assembly, a stator assembly, and a rotor assembly. The support assembly comprises an upper support and a lower support that are assembled and connected to each other. The upper and lower supports are sleeved on the central shaft and rotatably connected to it. The rotor assembly is rotatably supported on the central shaft via a bearing assembly. The support assembly partially encloses and supports the rotor assembly from the outside, giving the motor an overall internal rotor motor mounting configuration. This invention employs a composite structure of "external rotor core + internal rotor shape," with the rotor assembly located on the inner side in an external rotor form, ensuring high torque density and high rotational inertia. Furthermore, the semi-enclosed support structure provides excellent protection (preventing contact with foreign objects and collision deformation) while retaining necessary ventilation openings, allowing the motor to effectively dissipate heat even in a closed environment, thus balancing protection level and heat dissipation performance. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the composite structure external rotor brushless motor in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional view of the overall structure of the composite structure external rotor brushless motor in Embodiment 1 of the present invention; Figure 3 This is an exploded view of the composite structure external rotor brushless motor in Embodiment 1 of the present invention; Figure 4 for Figure 3 A three-dimensional structural diagram of the copper bushing; Figure 5 This is a schematic diagram of the assembly of the upper and lower supports fixed by riveting in Embodiment 2 of the present invention. Figure 6 This is a schematic diagram of the initial assembly state of the upper and lower brackets in Embodiment 3 of the present invention, where they are fixed by rotational insertion. Figure 7 This is a schematic diagram of the assembled state of the upper and lower brackets fixed by rotational insertion in Embodiment 3 of the present invention.

[0024] The annotations in the attached figures are explained as follows: 1. Central axis; 2. Bracket assembly; 21. Upper bracket; 211. Bearing boss; 2111. First receiving cavity; 212. Notch; 213. Receiving groove; 2131. Wide opening; 214. Circular column; 22. Lower bracket; 221. Base; 2211. Second receiving cavity; 2212. Arc groove; 222. Support cylinder; 223. Bearing platform; 225. Cable guide plate; 226. Protruding edge; 227. Locking strip; 228. Sealing ring; 229. Silicone ring; 3. Stator assembly; 31. Stator core; 4. Rotor assembly; 41. Housing; 42. Magnet; 43. Copper sleeve; 431. Circular part; 432. Straight cylinder part; 433. Flip-up part; 51. First bearing; 52. Second bearing. Detailed Implementation

[0025] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0026] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Example 1

[0028] like Figures 1 to 7 As shown, this invention provides a composite structure external rotor brushless motor, including a central shaft 1, a support assembly 2, a stator assembly 3, and a rotor assembly 4. The core idea of ​​this invention is to adopt a composite structure scheme of "external rotor core + internal rotor shape", using the rotating outer shell of a traditional external rotor motor (i.e., rotor assembly 4) as the inner rotating component, and adding a fixed support assembly 2 as a protective housing on the outside, so that the overall shape and installation method of the motor are close to those of an internal rotor motor, while optimizing the rotor support and concentricity maintenance structure.

[0029] The central shaft 1 is the central load-bearing element of the motor, made of high-strength metal material (such as stainless steel or alloy steel), and extends along the axial direction of the motor. The central area of ​​the central shaft 1 provides a supporting reference for the rotor assembly 4 and the bracket assembly 2. The outer circumferential surface of the central shaft 1 is provided with knurled texture, with the knurling pattern evenly distributed along the circumference and axial direction of the central shaft 1, used for bonding and fixing the two bearings. During assembly, structural adhesive is applied to the knurled areas, filling the knurling pattern, and a strong connection is formed after curing. This combination of knurling and adhesive fixing effectively eliminates the gap between the central shaft 1 and the bearings, reduces vibration and noise caused by the gap during high-speed operation of the motor, and improves the dynamic stability of the entire machine.

[0030] The support assembly 2 includes an upper support 21 and a lower support 22 that are assembled and connected to each other. Both the upper support 21 and the lower support 22 are sleeved on the central shaft 1 and rotatably connected to it. Specifically, the central shaft 1 passes through the central holes of the upper support 21 and the lower support 22, and the rotatable connection between the support assembly 2 and the central shaft 1 is achieved through bearings (i.e., the first bearing 51 and the second bearing 52 described below). When the motor is operating, the support assembly 2 acts as a fixed protective housing, fixed to the equipment frame or support by an external mounting structure, and does not rotate with the rotor assembly 4.

[0031] The lower support 22 includes a base 221 and a support cylinder 222 disposed on the base 221. A shaft hole for the central shaft 1 to pass through is provided at the center of the base 221. A second receiving cavity 2211 is also provided in the middle of the base 221, which is axially connected to the internal space of the support cylinder 222 and is used to accommodate the second bearing 52. A bearing platform 223 protrudes from the upper end face of the base 221 of the lower support 22, extending upward from the upper end face of the lower support 22 and forming a platform shape. The support cylinder 222 extends upward from the upper surface of the base 221, forming a cylinder shape, with an outer diameter smaller than the inner diameter of the rotor assembly 4, so that the rotor assembly 4 can be fitted onto its exterior and rotate freely. The height of the support cylinder 222 is not less than 3 / 4 of the height of the stator core 31, preferably equal to or slightly greater than 3 / 4 of the height of the stator core 31, so that most of the stator core 31 is supported and covered by the support cylinder 222. When the height of the supporting cylinder 222 reaches more than 3 / 4 of the height of the stator core 31, the stator core 31 can obtain sufficient radial support stiffness, reducing stator deformation caused by rotation. At the same time, the cylinder wall of the supporting cylinder 222 can serve as a heat dissipation channel, conducting the heat generated by the stator core 31 during operation to the base 221, and then dissipating the heat to the outside from the base 221, thereby improving the heat dissipation conditions of the stator core 31. The base 221 has screw holes at its four corners, and an arc-shaped groove 2212 is formed on the end face of the screw holes. The arc-shaped groove 2212 extends circumferentially along the end face of the base 221 and is arc-shaped.

[0032] The upper support 21 has a U-shaped structure, including a top wall and two side walls extending downwards from both sides of the top wall. A circular column 214 is provided at the bottom of the side wall, and the circular column 214 on the side wall of the upper support 21 and the arc-shaped groove 2212 of the base 221 form a positioning fit. During assembly, the upper support 21 and the lower support 22 are aligned and fastened, so that the circular column 214 is inserted into the arc-shaped groove 2212. Through the guiding and limiting effect of the arc surface of the arc-shaped groove 2212, the upper support 21 is precisely positioned radially and angularly relative to the lower support 22, thereby fixing the upper support 21. This positioning fit structure between the arc-shaped groove 2212 and the circular column 214 not only improves the alignment accuracy during assembly and ensures a uniform gap between the stator assembly 3 and the rotor assembly 4, but also effectively suppresses the radial runout of the stator core 31 caused by vibration or temperature changes during long-term operation, enhancing the operating stability of the motor. A bearing boss 211 protrudes from the center of the top wall. The bearing boss 211 extends upwards from the top wall in a cylindrical shape and has a first receiving cavity 2111 inside for accommodating and positioning the first bearing 51. The inner diameter of the bearing boss 211 matches the outer diameter of the first bearing 51, allowing the outer ring of the first bearing 51 to be interference-fitted with the bearing boss 211 or fixed with adhesive. The two side walls of the upper bracket 21 are respectively assembled and connected to the corresponding parts of the lower bracket 22 by screws, riveting, or rotary insertion. This will be described in detail below with reference to specific embodiments.

[0033] The stator assembly 3 is fixed to the supporting cylinder 222 and includes a stator core 31 and windings (not shown) disposed on the stator core 31. The stator core 31 is formed by stacking silicon steel sheets, is cylindrical, and is fitted onto the outside of the supporting cylinder 222 and fixed by interference fit, key connection, or fasteners. The windings are formed by winding enameled wire according to a preset winding method and are embedded in the toothed grooves of the stator core 31. A wire guide plate 225 is also provided on the lower bracket 22, with through holes for the output leads to pass through. After being led out, the output leads pass through the through holes on the wire guide plate 225 and are led out from the bottom or side of the bracket assembly 2, achieving orderly arrangement and fixation of the leads.

[0034] The rotor assembly 4 is cylindrically sleeved outside the stator assembly 3, maintaining a uniform air gap between them. The rotor assembly 4 includes a housing 41 and magnets 42 disposed on the inner wall of the housing 41. The housing 41 is cylindrical, formed by stamping or stretching a thin metal sheet, and magnets 42 are fixed to its inner wall. The magnets 42 are permanent magnets, uniformly arranged along the inner circumference of the housing 41, radially opposite to the stator core 31, and have an air gap. A copper sleeve 43 is provided at the center of the end (upper end face) of the housing 41, and the copper sleeve 43 is connected to the housing 41 by riveting. The copper sleeve 43 includes an integrally formed annular portion 431, a flip-up portion 433, and a straight cylindrical portion 432, with the straight cylindrical portion 432 vertically disposed on the annular portion 431. The flip-up portion 433 is disposed on the annular portion 431 and close to the straight cylindrical portion 432. The annular portion 431 is ring-shaped and fits against the end face of the housing 41. An external tool is used to press against the flip-open portion 433, causing it to flip and fit against the other end face of the housing 41, achieving clamping and riveting fixation. The straight cylindrical portion 432 extends axially from the center of the annular portion 431 and is sleeved on the outside of the central shaft 1. The copper sleeve 43 adopts an integrally formed annular portion 431 and straight cylindrical portion 432 structure, ensuring the concentricity accuracy of the copper sleeve 43 itself. Compared with traditional hard connections (such as welding or interference fit), the riveting connection method has the advantages of reliable connection, no thermal deformation, and good concentricity stability, avoiding the problems of insufficient holding force and concentricity deviation caused by thermal stress in hard connections. The copper sleeve 43 is made of copper alloy, which has good wear resistance and self-lubricating properties, reducing friction and wear between it and the central shaft 1. The straight section 432 has a certain height and covers and supports the central shaft 1. This can prevent the central shaft 1 from tilting vertically due to collision or falling of the components of the housing 41 and the central shaft 1 during the tooling process. This would cause the final product to produce abnormal noise and have low energy efficiency.

[0035] The rotor assembly 4 is rotatably supported on the central shaft 1 by a bearing assembly. The bearing assembly includes a first bearing 51 and a second bearing 52 respectively located at both axial ends of the rotor assembly 4. Both the first bearing 51 and the second bearing 52 are sleeved on the central shaft 1. Specifically, the first bearing 51 is accommodated in the first receiving cavity 2111 of the bearing boss 211 of the upper bracket 21. The outer ring of the first bearing 51 is fixedly connected to the bearing boss 211 (interference fit or glue fixation), and the inner ring of the first bearing 51 is clearance-fitted to the central shaft 1. A rigid collar is provided on one side of the joint between the first bearing 51 and the central shaft 1 to fix the first bearing 51 and prevent axial displacement. The second bearing 52 is accommodated in the second receiving cavity 2211 in the middle of the base 221 of the lower bracket 22. The outer ring of the second bearing 52 is fixedly connected to the lower bracket 22 (interference fit or glue fixation), and the inner ring of the second bearing 52 is clearance-fitted to the central shaft 1. The axial distance L1 between the first bearing 51 and the second bearing 52 is not less than 0.75 times the axial length L2 of the rotor assembly 4 (i.e., L1 ≥ 0.75L2). By setting the first bearing 51 and the second bearing 52 at the two axial ends of the rotor assembly 4 respectively, and ensuring sufficient span between the two bearings, the cantilever effect of the rotor assembly 4 is effectively suppressed, the rotor yaw during high-speed rotation is significantly reduced, and the dynamic stability of the motor operation is significantly improved. This is something that cannot be achieved by using only a single bearing or insufficient bearing span in traditional external rotor motors. A sealing ring 228 is provided on the axial end side of the second bearing 52. The sealing ring 228 and the second bearing 52 are stacked and placed in the second receiving cavity 2211. The sealing ring 228 can effectively protect the second bearing 52 from impacts from external hard objects or the influence of moisture, which is beneficial for the electric hair clipper in the humid environment of the bathroom, protecting the second bearing 52 and improving the product's service life. A silicone ring 229 is also provided between the sealing ring 228 and the second bearing 52, which can further improve the product's sealing performance and quietness during high-speed operation.

[0036] In this embodiment, the assembly connection between the upper bracket 21 and the lower bracket 22 is achieved by screw fixing. Specifically, the lower end of the side wall of the upper bracket 21 is provided with a screw through hole, and the corresponding position of the lower bracket 22 is provided with a threaded hole. By passing a screw through the screw through hole and screwing it into the threaded hole, a firm connection between the upper bracket 21 and the lower bracket 22 is achieved. The screw fixing method is convenient for assembly and disassembly and is suitable for application scenarios that require frequent maintenance or disassembly.

[0037] The support assembly 2 has a semi-enclosed structure, covering the main exposed areas of the rotor assembly 4, including most of the circumferential area and one end face (top face) of the rotor assembly 4, while retaining axial or radial ventilation openings to balance protection level and heat dissipation requirements. The design concept of the semi-enclosed support structure is: not to pursue full enclosure (full enclosure would affect heat dissipation and increase costs), but to cover the critical areas of the rotor assembly 4 most susceptible to external forces, while retaining necessary ventilation channels to ensure sufficient heat dissipation for the motor during operation. This semi-enclosed structure avoids direct contact between the human body and rotating parts, improving safety; in the event of an external collision or drop, the support assembly 2 absorbs the impact force first, reducing the risk of direct damage to the rotor assembly 4 and lowering the overall scrap rate.

[0038] The working principle of this invention is as follows: After the motor is powered on, three-phase alternating current is applied to the stator, generating a rotating magnetic field. This rotating magnetic field interacts with the permanent magnet magnetic field of the rotor magnet 42, driving the rotor assembly 4 to rotate around the central axis 1. Since the rotor assembly 4 is cylindrically sleeved outside the stator assembly 3, the electromagnetic force has a large radius of action and a long lever arm, resulting in a high output torque density, comparable to that of an external rotor motor. Simultaneously, the bracket assembly 2 partially wraps around and supports the rotor assembly 4 from the outside, making the overall shape and installation method of the motor consistent with that of an internal rotor motor, thus possessing the high protection level and excellent installation compatibility of an internal rotor motor. The double-bearing support structure ensures the dynamic stability of the rotor assembly 4 during high-speed rotation, the positioning and matching structure of the arc groove 2212 and the circular column 214 ensures the concentricity between the stator assembly 3 and the rotor assembly 4, and the semi-enclosed bracket structure balances protection and heat dissipation requirements. Example 2

[0039] This embodiment is basically the same as Embodiment 1, except that the assembly connection between the upper bracket 21 and the lower bracket 22 is fixed by riveting. Specifically, as shown... Figure 5 As shown, the lower bracket 22 has outwardly extending protruding edges 226 on both sides (i.e., the upper outer walls of the supporting cylinder 222), and rivet holes are provided on the protruding edges 226. The outer end of the upper bracket 21 (i.e., the lower end of the side wall) has a recess 212 that matches the protruding edges 226. The shape and size of the recess 212 correspond to the protruding edges 226, and rivet holes are also provided on the recess 212. During assembly, the recess 212 of the upper bracket 21 is aligned with the protruding edges 226 of the lower bracket 22 and fitted into place. Then, rivets are used to pass through the rivet holes on the protruding edges 226 and the recess 212 to rivet and fix the protruding edges 226 and the recess 212. The riveting fixing method has high connection strength, does not require additional screws or other fasteners, and is suitable for mass production applications that do not require frequent disassembly, effectively reducing production costs and improving assembly efficiency. Example 3

[0040] This embodiment is basically the same as Embodiment 1, except that the assembly connection between the upper bracket 21 and the lower bracket 22 adopts a rotary plug-in fixing method. Specifically, as shown... Figure 6 and 7 As shown, the outer bottom of the upper bracket 21 (i.e., the lower inner surface of the side wall) is provided with a receiving groove 213. The receiving groove 213 extends circumferentially along the upper bracket 21 and is arc-shaped. Its inlet end is provided with a wide opening 2131 to facilitate the insertion of the retaining strip 227. The inner top of the lower bracket 22 (i.e., the inner side of the upper end face of the supporting cylinder 222) is provided with a retaining strip 227. The retaining strip 227 extends circumferentially along the lower bracket 22 and is arc-shaped. The shape and size of the retaining strip 227 match the receiving groove 213. During assembly, the upper bracket 21 is fitted onto the lower bracket 22, so that the retaining strip 227 is aligned with the wide opening at the inlet end of the receiving groove 213. Then, the upper bracket 21 (or the lower bracket 22) is rotated relative to each other, so that the retaining strip 227 slides along the receiving groove 213 and finally engages at the end positioning position of the receiving groove 213, thereby achieving rapid assembly of the upper bracket 21 and the lower bracket 22. The rotary plug-in fixing method eliminates the need for fasteners such as screws and rivets, resulting in extremely high assembly efficiency and making it suitable for applications involving large-scale automated assembly. Example 4

[0041] This embodiment is basically the same as Embodiment 1, except that the height of the supporting cylinder 222 is equal to 3 / 4 of the height of the stator core 31, and the entire axial length of the stator core 31 is mostly covered and supported by the supporting cylinder 222. With this structure, the stator core 31 achieves complete radial support while ensuring lightweight design, further improving rigidity and heat dissipation performance. Simultaneously, the cylinder wall of the supporting cylinder 222 can more comprehensively conduct the heat generated by the stator core 31 during operation to the base 221 and dissipate it outwards, effectively reducing the operating temperature of the stator core 31 and extending the service life of the magnet 42.

[0042] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A composite structure external rotor brushless motor, characterized in that, Central axis; A support assembly includes an upper support and a lower support that are assembled and connected to each other. The upper support and the lower support are sleeved on the central shaft and rotatably connected to the central shaft. The lower support includes a base and a support cylinder disposed on the base. A stator assembly, fixed to the supporting cylinder, includes a stator core and windings disposed on the stator core, wherein the supporting cylinder is interference-fitted with the inner wall of the stator core; The rotor assembly is cylindrically sleeved outside the stator assembly, including a housing and a magnet disposed on the inner side wall of the housing. The rotor assembly is rotatably supported on the central shaft by a bearing assembly. The bracket assembly partially wraps around and supports the rotor assembly from the outside, so that the motor as a whole is installed in the form of an inner rotor motor.

2. The composite structure external rotor brushless motor according to claim 1, characterized in that, The bearing assembly includes a first bearing and a second bearing respectively located at both axial ends of the rotor assembly. The first bearing and the second bearing are both sleeved on the central shaft, and the axial distance between the first bearing and the second bearing is not less than 0.75 times the axial length of the rotor assembly.

3. The composite structure external rotor brushless motor according to claim 2, characterized in that, The outer ring of the first bearing is fixedly connected to the upper bracket, and the inner ring of the first bearing is clearance-fitted with the central shaft; the outer ring of the second bearing is fixedly connected to the lower bracket, and the inner ring of the second bearing is clearance-fitted with the central shaft; the outer circumferential surface of the central shaft is provided with knurled texture.

4. The composite structure external rotor brushless motor according to claim 1, characterized in that, The rotor assembly also includes a copper sleeve, which is connected to the housing by riveting. The copper sleeve includes an integrally formed annular portion, a flip-up portion, and a straight cylindrical portion. The straight cylindrical portion is vertically disposed on the annular portion, and the flip-up portion is disposed on the annular portion and close to the straight cylindrical portion.

5. The composite structure external rotor brushless motor according to claim 1, characterized in that, The upper and lower brackets are assembled and connected by any one of the following methods: screw fixing, riveting fixing, or rotary plug fixing.

6. The composite structure external rotor brushless motor according to claim 5, characterized in that, When riveting is used for fixing, the lower bracket has protruding edges on both sides, and the outer end of the upper bracket has a notch that matches the protruding edges; when rotating and inserting is used for fixing, the bottom outer side of the upper bracket has a receiving groove, and the top inner side of the lower bracket has a locking strip, which matches and engages with the receiving groove.

7. The composite structure external rotor brushless motor according to claim 1, characterized in that, The upper support has a U-shaped structure, and a bearing boss is protruding from the top of the upper support. The bearing boss has a first receiving cavity inside, and the first bearing is matched and received in the first receiving cavity. The lower support has a second receiving cavity in the middle of the base. The second receiving cavity is axially connected to the internal space of the supporting cylinder, and the second bearing is matched and received in the second receiving cavity.

8. The composite structure external rotor brushless motor according to claim 1, characterized in that, The height of the supporting cylinder is not less than 3 / 4 of the height of the stator core, so that at least most of the stator core is supported by the supporting cylinder.

9. The composite structure external rotor brushless motor according to claim 1, characterized in that, The support assembly is a semi-enclosed structure that covers the main exposed area of ​​the rotor assembly while retaining axial or radial ventilation openings to balance the protection level and heat dissipation requirements.

10. An electric hair clipper, characterized in that, A composite structure external rotor brushless motor comprising any one of claims 1 to 9 above.

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