Outer rotor brushless motor
By adopting powder metallurgy technology to die-cast the mating layer in the rotor assembly of the outer rotor brushless motor, and combining the punching weight reduction balance technology, the problems of difficult operation of the motor rotor balance and waste of resources are solved, achieving an efficient and low-cost balance effect.
Patent Information
- Application Number
- CN202310947995.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-28
- Publication Date
- 2025-02-14
AI Technical Summary
In terms of rotor balance, existing motors have problems such as manual operation difficulty, low production efficiency, high safety hazards and serious resource waste in traditional weight reduction methods. Especially in external rotor motors, traditional cutting cannot be performed due to wind blades installed on the end surface. Cut weight.
The powder metallurgy process is used to die-cast the mating layer on the inner wall of the central through-hole of the rotor assembly, and die-casting is integrated with the air blades. In combination with the rotor case, the rotor case is drilled and weight-reducing balance is performed, and the imbalance measurement is corrected by adjusting the number and position of the weight-reducing holes.
It effectively reduces the initial imbalance of the motor, improves production efficiency, reduces operational difficulty and cost, and avoids waste of resources.
Smart Images
Figure CN119448619A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of motors, and in particular relates to an outer rotor brushless motor. Background Art
[0002] The motor consists of two parts: the rotor and the stator. The dynamic balance of the rotor has a great influence on the performance of the motor. The inertia force or inertia moment of the unbalanced mass of the rotor is one of the main reasons for the vibration of rotating machinery. To eliminate or reduce the vibration of the motor, the first main method to consider is to balance the rotor so that the vibration of the machine is limited to the allowable range.
[0003] Existing motors generally use the method of adding weight or reducing weight to balance the rotor. For the weight-adding method, it is currently necessary to manually add dynamic balancing mud, which greatly affects production efficiency and increases the difficulty of operation. For the weight reduction method, the traditional motor rotor core is reduced in weight at both end faces. Weight reduction generally uses a cutting machine to cut metal. This method has very large disadvantages and has very large safety hazards. In addition, the amount of cutting is difficult to control. The rotor that is dynamically balanced by cutting cannot be reused and can be said to be a disposable item, which seriously wastes resources. At the same time, for external rotor motors, since the end faces are equipped with fan blades, it is impossible to cut and reduce weight on the end faces. Summary of the invention
[0004] The purpose of the present invention is to provide an outer rotor brushless motor and a magnetic steel mounting structure thereof to solve the above problems. To this end, the technical solution adopted by the present invention is as follows:
[0005] An outer rotor brushless motor, the outer rotor brushless motor includes a rotor assembly, wherein the rotor assembly includes a shell and a fan blade, the fan blade is fixedly connected to the shell, the fan blade has an intermediate connecting portion, the intermediate connecting portion has a central through hole for a rotating shaft to pass through, the inner wall of the central through hole is fixedly provided with a matching layer, the rotating shaft and the matching layer are interference fit, and the hardness of the matching layer is greater than the hardness of the inner wall.
[0006] Furthermore, the hardness of the matching layer is greater than or equal to 30HRC. Preferably, the hardness of the matching layer is 40-55HRC.
[0007] Furthermore, the matching layer is a powder metallurgy part or an alloy part.
[0008] Furthermore, the matching layer and the fan blade are integrally die-cast.
[0009] Furthermore, the interference between the rotating shaft and the matching layer is 0.05-0.12 mm.
[0010] Furthermore, a knurled area is provided on the rotating shaft, and the knurled area is interference fit with the matching layer.
[0011] Furthermore, the thickness of the matching layer is greater than 5 mm, and preferably, the thickness of the matching layer is 5 to 7 mm.
[0012] Furthermore, the length of the matching layer is greater than 30 mm.
[0013] Furthermore, a weight-reducing hole is provided on the outer wall of the shell, so that the dynamic unbalance of the outer rotor brushless motor is maintained at less than or equal to 80 mg.
[0014] Furthermore, the diameter of the weight-reducing hole is greater than or equal to 5 mm, and the depth is less than or equal to 2 mm.
[0015] Furthermore, a plurality of annular adhesive grooves are provided on the inner side wall of the shell, and a plurality of strip-shaped magnetic steels evenly spaced apart in the circumferential direction are pasted on the inner wall of the shell.
[0016] Furthermore, a plurality of mounting grooves extending in the axial direction are arranged on the inner side wall of the shell, and the strip magnetic steel is fixedly installed in the mounting grooves, and the thickness of the strip magnetic steel is greater than the depth of the mounting grooves.
[0017] Furthermore, the depth of the mounting groove is 1 / 4 to 1 / 2 of the thickness of the strip magnetic steel.
[0018] Furthermore, a plurality of positioning ribs extending downward are formed on the annular bottom of the fan blade, and the positioning ribs are inserted into the gap between two adjacent strip-shaped magnetic steels.
[0019] The present invention adopts powder metallurgy technology in the motor structure, so that the initial imbalance of the motor is greatly reduced. In combination with this feature, the rotor casing is punched to reduce weight and balance, which can effectively correct the imbalance of the rotor without manual operation, greatly improving production efficiency, reducing operating difficulty and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 is a perspective view of an outer rotor brushless motor of the present invention;
[0021] Figure 2 yes Figure 1 An exploded view of an outer rotor brushless motor is shown;
[0022] Figure 3 yes Figure 1 A perspective view of the fan blades of the outer rotor brushless motor shown;
[0023] Figure 4 yes Figure 1 A perspective view of the housing of the outer rotor brushless motor shown;
[0024] Figure 5 yes Figure 1 A side view of an outer rotor brushless motor is shown;
[0025] Figure 6 is along Figure 5 A cross-sectional view of an outer rotor brushless motor taken along line AA in FIG. DETAILED DESCRIPTION
[0026] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings so that the purpose, features and advantages of the present invention can be more clearly understood. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.
[0027] In the following description, certain specific details are set forth for the purpose of illustrating the various disclosed embodiments to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other cases, well-known devices, structures, and techniques associated with the present application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.
[0028] References throughout the specification to "one embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.
[0029] In the following description, in order to clearly show the structure and working mode of the present invention, many directional words will be used for description, but the words "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", "down", etc. should be understood as convenient terms and should not be understood as restrictive terms.
[0030] like Figures 1 to 6As shown, an outer rotor brushless motor includes a stator assembly 1, a rotor assembly 2, and a rotating shaft 3, wherein the stator assembly 1 includes a base 11 and a stator core 12 and a plastic frame 13 fixedly mounted on the base 11, and the stator core 12 and the plastic frame 13 are integrally injection molded. The rotor assembly 2 includes a housing 21, a fan blade 22, and a magnetic steel 23. The fan blade 22 can be die-casted from aluminum or other metals. The fan blade 22 is fixedly connected to the housing 21, and the fan blade 22 has an intermediate connection portion, which has a central through hole 221 for the rotating shaft 3 to pass through, and the inner wall of the central through hole 221 has a matching layer 222, and the rotating shaft 3 is interference-fitted with the matching layer 222. The hardness of the matching layer 222 is greater than the hardness of the inner wall of the central through hole 221. The hardness of the matching layer 222 is usually above 40HRC, and preferably, the hardness of the matching layer 222 is 40-55HRC. By providing the matching layer 222, due to the greater hardness of the matching layer 222, on the one hand, slippage between the center through hole and the rotating shaft can be prevented, thereby increasing the torque of the motor. For example, the torque of the motor can be increased from 40 to 50 N·m (Newton meters) to 150 to 200 N·m; on the other hand, the rotating shaft can directly have an interference fit with the matching layer, thereby avoiding the need to add other components (such as keyways, etc.) and reducing the initial imbalance of the resistor.
[0031] The matching layer 222 may be made of powder metallurgy or alloy materials, etc. Preferably, the matching layer 222 may be a powder metallurgy part made of metal powders such as copper and iron by a powder metallurgy process.
[0032] Preferably, the matching layer 222 is integrally die-cast with the fan blade 22 to improve the bonding strength between the matching layer 222 and the fan blade 22. In one embodiment, the powder metallurgy part is fixed at the center through hole 221 when the aluminum is die-cast (i.e., the fan blade 22 is manufactured), so that the powder metallurgy part and the fan blade 22 are die-cast together. Usually, the surface of the outer wall of the powder metallurgy part is a rough surface to further improve the bonding force with the fan blade 22. For example, a hobbing is provided on the surface of the outer wall of the powder metallurgy part. Since the fan blade is made of aluminum, its hardness is not high. Therefore, by die-casting the powder metallurgy part on the inner wall of the center through hole of the fan blade, on the one hand, the hardness of the center through hole can be improved to prevent slipping between the center through hole and the rotating shaft, and on the other hand, the need to add other components (such as keyways, etc.) can be avoided, thereby reducing the initial imbalance of the motor. After the initial unbalance is reduced, when the device detects that the weight of a certain part of the housing 21 is too heavy, that is, when the unbalance exceeds 80 mg, the unbalance is directly calculated, and a weight reduction hole 211 is processed at that place to maintain the unbalance at less than or equal to 80 mg. This method is used to adjust the unbalance of the rotor without adding additional dynamic balancing mud for weighting, which is simple and convenient to operate and low in cost.
[0033] The number, size and position of the weight-reducing holes 211 of the housing 21 can be determined according to the result of the rotor dynamic balance test. Generally, the diameter of the weight-reducing holes 211 is greater than or equal to 5 mm, preferably 5 to 10 mm, and the depth is less than or equal to 2 mm.
[0034] In this embodiment, the base 11 includes a roughly triangular bottom and a cylindrical connecting portion extending vertically upward from the bottom, and the lower surface of the bottom has a bearing mounting portion connected to the inner cavity of the cylindrical connecting portion. A fixing hole is provided on each of the three corners of the bottom 11 to facilitate the installation of the motor. The stator core 12 is sleeved on the cylindrical connecting portion, and its upper end surface has another bearing mounting portion connected to the inner cavity of the cylindrical connecting portion. The rotating shaft 3 is mounted on the stator assembly 1 by two bearings 4 fixedly mounted on the two bearing mounting portions. Preferably, the upper bearing 4 is a thin-walled bearing and the lower bearing 4 is a deep groove ball bearing. In addition, in order to prevent the rotating shaft 3 from falling off, the two ends of the rotating shaft 3 are fixed by corresponding shaft circlips 5. The shaft circlip 5 is commercially available, and its structure is not further described in this article.
[0035] like Figure 3 and 6 As shown, the fan blade 22 includes an annular bottom, an annular top, an intermediate connecting portion and a plurality of blades 220. The annular bottom of the fan blade 22 is formed with a plurality of positioning ribs 223 extending downward, and the positioning ribs 223 are used to fix the fan blade 22 to the shell 21. A plurality of blades 220 are annularly fixedly formed on the annular bottom and the annular top. A plurality of radial ribs 224 are formed between the intermediate connecting portion and the annular top to increase the strength of the fan blade 22. The plurality of radial ribs 224 are distributed radially. In this embodiment, the radial ribs 224 are inclined downward from the annular top to the intermediate connecting portion, that is, the radial ribs 224 are higher at one end of the annular top than at one end of the intermediate connecting portion. The intermediate connecting portion is an inverted frustum structure.
[0036] like Figure 3 , 4As shown in Figures 6 and 7, in this embodiment, a plurality of (14 are shown) strip-shaped magnetic steels 23 evenly spaced in the circumferential direction are pasted on the inner wall of the shell 21. When the fan blade 22 is installed in the shell 21, the positioning rib 223 is inserted into the gap between two adjacent magnetic steels 23 from top to bottom. That is, the size of the gap between two adjacent magnetic steels 23 is substantially consistent with the positioning rib 223. By clamping the positioning rib 223 between two adjacent magnetic steels 23, the structure of the shell 21 can be simplified and the production cost can be reduced. Preferably, a plurality of annular glue grooves 212 are provided on the inner wall of the shell 21, so that the magnetic steel 23 can be more firmly bonded to the inside of the shell 21. Usually, the depth of the annular glue groove 212 is about 1 mm to avoid affecting the strength of the shell 21. In this embodiment, the thickness of the magnetic steel 23 is 2 mm, the width is 10 mm, and the length is 45 mm. It should be understood that the present invention does not limit the size of the magnetic steel 23.
[0037] In another embodiment, the inner wall of the shell 21 is not provided with an annular glue groove 212, but is provided with a plurality of circumferentially evenly spaced mounting grooves extending along the axial direction, the depth of the mounting groove being less than the thickness of the strip magnetic steel 23, so that the strip magnetic steel 23 protrudes from the inner wall of the shell 21 by a certain height when fixedly installed (for example, bonded) in the mounting groove to clamp the positioning rib 223. At the same time, the strip magnetic steel 23 protrudes from the inner wall of the shell 21, which can reduce magnetic resistance loss, help improve the electromagnetic energy conversion efficiency, and thus improve the performance of the motor. Generally, the depth of the mounting groove is 1 / 4 to 1 / 2 of the thickness of the strip magnetic steel 23. That is, the ratio of the thickness of the magnetic steel 23 outside the mounting groove to the thickness of the strip magnetic steel 23 in the mounting groove is 1:1 to 3:1. In one embodiment, the depth of the mounting groove is about 1 mm to avoid affecting the strength of the shell 21.
[0038] In this embodiment, the stator assembly 1 has 12 salient poles, and the rotor assembly 2 has 14 magnetic steels 23. That is, the outer rotor brushless motor is a 14-slot 12-pole motor. It should be understood that the number of slots and poles of the outer rotor brushless motor is not limited to the embodiment shown.
[0039] like Figure 6 As shown, the rotating shaft 3 is provided with a knurling area 31, and the knurling area 31 is interference-fitted with the matching layer (specifically, the powder metallurgy part) 222. The knurling process can increase the friction between the rotating shaft 3 and the powder metallurgy part 222 to prevent slipping. In a specific embodiment, the interference is 5 to 12 wires, that is, 0.05 to 0.12 mm. In this embodiment, the knurling area 31 is composed of hobbing. The length of the knurling area 31 is substantially the same as the length of the powder metallurgy part 222. In some embodiments, the length of the powder metallurgy part 222 is greater than or equal to 30 mm, and the thickness is greater than or equal to 5 mm, preferably 5 to 7 mm.
[0040] The preferred embodiments of the present invention have been described in detail above, but it should be understood that after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims of this application.
Claims
1. An outer rotor brushless motor, comprising a rotor assembly, characterized in that: The rotor assembly includes a shell and a fan blade, wherein the fan blade is fixedly connected to the shell, and the fan blade has an intermediate connecting portion, wherein the intermediate connecting portion has a central through hole for a rotating shaft to pass through, and an inner wall of the central through hole is fixedly provided with a fitting layer, the rotating shaft is interference fit with the fitting layer, and the hardness of the fitting layer is greater than the hardness of the inner wall.
2. The outer rotor brushless motor according to claim 1, characterized in that: The hardness of the matching layer is greater than or equal to 30HRC. Preferably, the hardness of the matching layer is 40-55HRC.
3. The outer rotor brushless motor according to claim 1, characterized in that: The matching layer is a powder metallurgy part or an alloy part.
4. The outer rotor brushless motor according to claim 1, characterized in that: The matching layer and the fan blade are integrally die-cast.
5. The outer rotor brushless motor according to claim 1, characterized in that: The interference between the rotating shaft and the matching layer is 0.05-0.12 mm.
6. The outer rotor brushless motor according to claim 1, characterized in that: The rotating shaft is provided with a knurled area, and the knurled area is interference fit with the matching layer.
7. The outer rotor brushless motor according to claim 1, characterized in that: The thickness of the matching layer is greater than 5 mm, and preferably, the thickness of the matching layer is 5 to 7 mm.
8. The outer rotor brushless motor according to claim 1, characterized in that: The length of the matching layer is greater than 30 mm.
9. The outer rotor brushless motor according to claim 1, characterized in that: The outer wall of the shell is provided with a weight-reducing hole, so that the dynamic unbalance of the outer rotor brushless motor is maintained at less than or equal to 80 mg.
10. The outer rotor brushless motor according to claim 9, characterized in that: The diameter of the weight-reducing hole is greater than or equal to 5 mm, and the depth is less than or equal to 2 mm.
11. The outer rotor brushless motor according to claim 1, characterized in that: A plurality of annular adhesive grooves are arranged on the inner side wall of the shell, and a plurality of strip-shaped magnetic steels evenly spaced apart in the circumferential direction are pasted on the inner wall of the shell.
12. The outer rotor brushless motor according to claim 1, characterized in that: A plurality of mounting grooves extending in the axial direction are arranged on the inner side wall of the shell, and the strip magnetic steel is fixedly installed in the mounting grooves, and the thickness of the strip magnetic steel is greater than the depth of the mounting grooves.
13. The outer rotor brushless motor according to claim 12, characterized in that: The depth of the mounting groove is 1 / 4 to 1 / 2 of the thickness of the strip magnetic steel.
14. The outer rotor brushless motor according to claim 11 or 12, characterized in that: The annular bottom of the fan blade is formed with a plurality of positioning ribs extending downward, and the positioning ribs are inserted into the gap between two adjacent strip-shaped magnetic steels.