Permanent magnet brushless motor

Abstract

The utility model discloses a permanent magnet brushless motor, which comprises a stator module, a rotor module, a first bearing and a second bearing, the stator module comprises a base and an armature assembly, the rotor module comprises a shell, a rotating shaft and a permanent magnet, the shell comprises a main shell body and an end cover, the rotating shaft is arranged on the base through the first bearing and the second bearing, and the permanent magnet is arranged on the main shell body. The first end of the rotating shaft penetrates through the first bearing and then is fixedly connected with an end cover of the outer shell, the permanent magnet is a multi-pole magnetic ring, the permanent magnet is made of sintered neodymium iron boron materials, and the permanent magnet is directly installed on the inner wall of the main shell. The permanent magnet surrounds the armature assembly, and an air gap exists between the permanent magnet and the armature assembly. The permanent magnet provided by the utility model is a multi-pole magnetic ring and is made of sintered neodymium iron boron material, the magnetism is stronger, the permanent magnet can be directly arranged on the shell without being matched with an iron magnet yoke, the weight of the permanent magnet brushless motor can be effectively reduced, and the production efficiency can be improved.

Description

Technical Field

[0001] The utility model belongs to the field of motors, and more specifically, relates to a permanent magnet brushless motor. Background Art

[0002] Permanent magnet brushless motors are widely used in fields such as aerospace, robotics, industrial automation, medical engineering, automotive industry, military industry, and smart home. Their per capita usage has become an important indicator to measure a country's national living standards, industrial intelligence level, military modernization, etc. Improving key indicators such as the working efficiency and power density of motors is of great significance for enhancing the level of China's motor industry.

[0003] At present, for the commonly used permanent magnet brushless motors, the magnetism of the permanent magnet material is not high, resulting in the magnetic field strength of the permanent magnet not reaching a very high level. Such a permanent magnet still needs to be equipped with a relatively dense iron yoke and then installed on the motor housing, and assembled into a rotor assembly together, increasing the weight and volume of the rotor assembly of the permanent magnet brushless motor.

[0004] In addition, usually, the aluminum motor housing and base parts are made by die-casting aluminum process. However, the mechanical properties of the die-cast aluminum parts are poor (low yield strength and defects), and it is difficult to make a thin-walled structure. The overall structure is relatively "thick" (because the density of the die-cast aluminum parts is small, internal defects are likely to occur, and the material strength is low, so it is impossible to obtain a very thin part structure. A relatively thick part structure will increase the product weight and occupy more volume).

[0005] In order to reduce the weight as much as possible, the iron yoke and the motor housing are manufactured separately. The end of the motor housing is machined from aluminum material and hollowed out to reduce weight. Then, the two are assembled with the permanent magnet into a rotor assembly together, resulting in a large number of production processes and an increase in production costs. Summary of the Utility Model

[0006] In view of the above defects or improvement requirements of the prior art, the utility model provides a permanent magnet brushless motor. The permanent magnet is a multi-pole magnetic ring and is made of sintered neodymium iron boron material, which has strong magnetism. It can be directly installed on the housing without being installed together with a yoke, effectively reducing the weight of the permanent magnet brushless motor and improving the production efficiency.

[0007] To achieve the above object, according to the utility model, there is provided a permanent magnet brushless motor, which is characterized by comprising a stator module, a rotor module, a first bearing, and a second bearing, wherein:

[0008] The stator module includes a base and an armature assembly fixedly installed on the base. The armature assembly includes a stator core and an armature winding wound around the stator core. The leads on the armature winding are led out from the wire routing holes on the base;

[0009] The rotor module includes a housing, a rotating shaft, and a permanent magnet. The housing includes a main housing and an end cover disposed at one end of the main housing. The rotating shaft is mounted on the base through the first bearing and the second bearing, and the first end of the rotating shaft passes through the first bearing and is fixedly connected to the end cover of the housing. The permanent magnet is a multi-pole magnetic ring and is made of sintered neodymium iron boron material. The permanent magnet is directly mounted on the inner wall of the main housing. The permanent magnet surrounds the armature assembly and there is an air gap between the permanent magnet and the armature assembly.

[0010] Preferably, the inner diameter of the permanent magnet is 8 mm to 30 mm, the outer diameter is 10 mm to 40 mm, and the radial wall thickness is 0.5 mm to 3 mm.

[0011] Preferably, there are multiple permanent magnets and they are nested together inside and outside.

[0012] Preferably, the permanent magnet has an integral non-spliced structure.

[0013] Preferably, the main housing is generally cylindrical and the outer diameter of the main housing is 12 mm to 46 mm.

[0014] Preferably, the air gap between the permanent magnet and the armature assembly is 0.05 mm to 0.2 mm.

[0015] Preferably, the housing is made of 2024 aluminum alloy by powder metallurgy process;

[0016] Alternatively, the housing is made of 6061 aluminum alloy by powder injection process.

[0017] Preferably, the end cover abuts against the inner ring of the first bearing.

[0018] Preferably, the stator module further includes a preloading spring. The rotating shaft passes through the preloading spring. One end of the preloading spring abuts against the convex platform of the base and the other end abuts against the outer ring of the second bearing.

[0019] Preferably, the stator module further includes a gasket and a snap ring. The second end of the rotating shaft passes through the inner ring of the second bearing and the part of the rotating shaft passing through the second bearing is provided with the gasket and the snap ring. The gasket abuts against the inner ring of the second bearing, and the snap ring presses the gasket against the inner ring of the second bearing.

[0020] Generally speaking, compared with the prior art by the above technical solutions conceived by the present utility model, the following beneficial effects can be achieved:

[0021] 1) A permanent magnet brushless motor provided by the present utility model uses a sintered neodymium iron boron material with strong magnetism as a multi-pole magnetic ring, and there is no need to set a ferromagnetic magnetic yoke, which reduces the weight of the motor rotor assembly and is beneficial for use in application fields sensitive to weight. The moment of inertia of the motor rotor assembly is also correspondingly reduced, and the centrifugal force generated by high-speed operation is reduced, which is beneficial for reducing the bearing pressure load, thereby reducing the loss current and improving the working efficiency of the permanent magnet brushless motor.

[0022] 2) A permanent magnet brushless motor provided by the present utility model has an air gap in an extremely small range of 0.05 - 0.2 mm, which reduces the "obstruction" of the air with a very large magnetic resistance to the magnetic pressure of the magnet, so that the electromagnetic conversion efficiency of the motor can be significantly improved, and the efficiency and torque density can be improved.

[0023] 3) A permanent magnet brushless motor provided by the present utility model can be made into a thin-walled and structurally complex weight-reducing hollow structure by adopting an integrated process of aluminum alloy powder metallurgy or metal powder injection molding of high-strength aluminum alloy, which reduces the overall weight of the rotor assembly of the permanent magnet brushless motor. Moreover, the integrated forming process of high-strength aluminum alloy avoids the high-cost machining process, making the permanent magnet brushless motor product excellent in quality and reasonable in price. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the permanent magnet brushless motor;

[0025] Figure 2 is an exploded view of the permanent magnet brushless motor;

[0026] Figure 3 is a schematic diagram of the magnetic field line distribution after two permanent magnets are nested inside and outside each other;

[0027] Figure 4 is a schematic diagram of the magnetic pole distribution of the permanent magnet with a larger diameter;

[0028] Figure 5 is a schematic diagram of the magnetic pole distribution of the permanent magnet with a larger diameter;

[0029] Figure 6 is Figure 4 and Figure 5 is a schematic diagram of the magnetic pole distribution after two permanent magnets are nested inside and outside each other. DETAILED DESCRIPTION OF THE INVENTION

[0030] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. In addition, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0031] According to one aspect of the present utility model, a permanent magnet brushless motor is provided, which includes a stator module 1, a rotor module 2, a first bearing and a second bearing, wherein:

[0032] The stator module 1 includes a base 11 and an armature assembly 12 fixedly installed on the base 11. The armature assembly 12 includes a stator core 121 and an armature winding 122 wound around the stator core 121. A lead wire 123 on the armature winding 122 is led out from a wire routing hole on the base 11.

[0033] The rotor module 2 includes a housing 21, a rotating shaft 22 and the permanent magnet 23. The housing 21 includes a main housing 211 and an end cover 212 provided at one end of the main housing 211. The rotating shaft 22 is installed on the base 11 through the first bearing 3 and the second bearing 4. And the first end of the rotating shaft 22 passes through the first bearing 3 and is fixedly connected to the end cover 212 of the housing 21. The end cover 212 preferably abuts against the inner ring of the first bearing 3. The permanent magnet 23 is a multi-pole magnetic ring and the permanent magnet 23 is made of sintered neodymium iron boron material. The permanent magnet 23 is directly installed on the inner wall of the housing 21. The permanent magnet 23 surrounds the armature assembly 12 and there is an air gap 5 between the permanent magnet 23 and the armature assembly 12 (that is, the radial gap between the permanent magnet 23 and the armature assembly 12). The rotating shaft 22 is installed on the base 11 through the two bearings. Since the permanent magnet 23 is outside the outer armature assembly 12, therefore, the permanent magnet 23 of the permanent magnet brushless motor with this structure has an inner cohesive magnetism.

[0034] Furthermore, the main housing 211 is integrally cylindrical and the outer diameter of the main housing 211 is 12 mm to 46 mm. The permanent magnet brushless motor of the present utility model solves the problem that the magnetic field intensity of the permanent magnet of the power motor of the unmanned aerial vehicle is not high, and is particularly suitable for small unmanned aerial vehicles.

[0035] Furthermore, the permanent magnet brushless motor of the present utility model adopts a permanent magnet 23 without splicing as a whole, that is, it is not composed of tile magnets spliced together, but is a whole without splicing seams, which is convenient for magnetization, can improve the assembly efficiency, and does not need to be used in combination with an iron yoke. In addition, the air gap 5 (which is also the air gap of the permanent magnet brushless motor) between the permanent magnet 23 and the armature assembly 12 is 0.05 mm to 0.2 mm. By improving the processing accuracy and assembly process, the air gap 5 between the permanent magnet 23 and the armature assembly 12 reaches a very small range of 0.05 mm to 0.2 mm. Since the amplitude of the high-order harmonic components in the traditional magnet scheme is high and there are many of them, the electromagnetic noise and vibration are very obvious after reducing the air gap of the motor. Therefore, the air gap 5 cannot be reduced at will. The magnetic density of the air gap 5 of the magnetic ring provided by the present utility model is close to a perfect sine wave. By exploring the limit of the existing processing and assembly accuracy, the air gap 5 (radial gap) is reduced, and the "obstruction" of the air with a very large magnetic resistance to the magnetic pressure of the magnet is reduced. Therefore, the electromagnetic conversion efficiency of the motor can be significantly improved, and the efficiency and torque density can be improved. Due to the good sinusoidal nature of the magnetic density waveform of the permanent magnet 23 of the present utility model and the small harmonic content, the inner wall of the permanent magnet 23 is as close as possible to the armature assembly 12 without interference between the stator module 1 and the rotor, so as to reduce the air gap 5. For conventional permanent magnets, the direction deviation of the magnetic field emitted from the permanent magnet (magnetic source) results in a high amplitude and a large amount of magnetic harmonics. The most direct manifestation is a large cogging torque. Because of its large torque fluctuation and large running vibration, it will be even greater if the air gap 5 of the motor becomes smaller, and a large amount of magnetic harmonics (especially high-order harmonics) will generate sharp and harsh electromagnetic noise during the operation of a high-speed motor.

[0036] Furthermore, the housing 21 is made of 2024 aluminum alloy by powder metallurgy process, or the housing 21 is made of 6061 aluminum alloy by powder injection process.

[0037] The housing 21 of the present utility model is made of aluminum alloy or composite aluminum alloy by powder metallurgy (PM) or metal powder injection molding (MIM) process. Many of its material characteristic indexes reach the level of 6-series aluminum alloy, and a few indexes are better than those of 6-series aluminum alloy. Therefore, the thin-wall degree that can be achieved by 6-series aluminum alloy can be realized. The powder metallurgy (PM) or metal powder injection molding (MIM) process is mainly used to process thin-wall parts with complex part structures in a low-cost way (Note: It is relatively rare to use powder metallurgy or metal powder injection molding (MIM) process for aluminum alloy, and it is more difficult to realize than the powder metallurgy or metal powder injection molding (MIM) process for ferroalloy).

[0038] The permanent magnet 23 of the present utility model does not need to be sleeved with a ferromagnetic iron yoke. By adopting an aluminum alloy forming process of powder metallurgy (PM) or metal powder injection molding (MIM), an end cover 212 with a thin-walled and complex structure of a weight-reducing hollow structure can be made, reducing the weight of the rotor of the motor, which is beneficial for use in application fields sensitive to weight. The moment of inertia of the rotor module of the motor is also correspondingly reduced, and the centrifugal force generated by high-speed operation is reduced, which is beneficial for reducing the bearing pressure load, thereby reducing the loss current and improving the motor efficiency. The high-strength aluminum alloy integrated forming process avoids the high-cost machining process and reduces the production cost of the permanent magnet brushless motor.

[0039] Further, the stator module 1 further includes a preloading spring 13, a gasket 14 and a snap ring 15. The rotating shaft 22 passes through the preloading spring 13. One end of the preloading spring 13 abuts against the boss of the base 11 and the other end abuts against the outer ring of the second bearing 4. And the second bearing 4 is a ball bearing. The second end of the rotating shaft 22 passes through the inner ring of the second bearing 4 and the part passing through the second bearing 4 is provided with the gasket 14 and the snap ring 15. The gasket 14 abuts against the inner ring of the second bearing 4, and the snap ring 15 presses the gasket 14 against the inner ring of the second bearing 4. The preloading spring 13 can apply an axial preloading force on the outer ring of the second bearing 4 to prevent the outer ring of the second bearing 4 from vibrating. In addition, the snap ring 15 can also apply a force on the inner ring of the second bearing 4 to prevent the inner ring from vibrating.

[0040] The sub-harmonics of the permanent magnet 23 adopted in the present utility model are almost non-existent. Moreover, reducing the air gap 5 of the motor will not cause obvious cogging torque, nor is there the influence of high-order harmonics. As long as there is no interference between the stator module 1 and the rotor module 2 of the motor, reducing the air gap 5 of the motor will not produce obvious adverse consequences. The magnetic pressure loss of the magnetic field generated by the permanent magnet 23 in the air gap 5 can be reduced, and the electromagnetic power / efficiency of the motor is improved.

[0041] Refer to Figures 3 to 6 , if the size of the permanent magnet 23 and the requirements for the high power of the motor are relatively high, and the radial thickness of the permanent magnet 23 is relatively large, limited by the size of the magnetizing fixture, the magnetizing fixture cannot generate enough magnetizing magnetic field coercivity, resulting in the permanent magnet 23 not being saturated magnetized, and even the magnetizing angle shifting, resulting in poor magnetic aggregation and weak magnetic field intensity of the permanent magnet 23. In this case, the thick permanent magnet 23 can be divided into two or three thin magnets nested inside and outside and assembled together. During assembly, the magnetic poles of the permanent magnet 23 attract each other to complete the magnetic pole alignment process, and the magnetic poles of the inner and outer magnets are formed in series, without increasing the assembly cost.

[0042] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A permanent magnet brushless motor, characterized in that, It includes a stator module, a rotor module, a first bearing and a second bearing, wherein: The stator module includes a base and an armature assembly fixedly installed on the base. The armature assembly includes a stator core and an armature winding wound around the stator core. The leads on the armature winding are led out from the wire routing holes on the base. The rotor module includes a housing, a rotating shaft and a permanent magnet. The housing includes a main housing and an end cover provided at one end of the main housing. The rotating shaft is installed on the base through the first bearing and the second bearing, and the first end of the rotating shaft passes through the first bearing and is fixedly connected to the end cover of the housing. The permanent magnet is a multi-pole magnetic ring and the permanent magnet is made of sintered neodymium iron boron material. The permanent magnet is directly installed on the inner wall of the main housing. The permanent magnet surrounds the armature assembly and there is an air gap between the permanent magnet and the armature assembly.

2. A permanent magnet brushless motor according to claim 1, characterized in that, The inner diameter of the permanent magnet is 8 mm to 30 mm, the outer diameter is 10 mm to 40 mm, and the radial wall thickness is 0.5 mm to 3 mm.

3. A permanent magnet brushless motor according to claim 1, characterized in that, There are multiple permanent magnets and they are nested inside and outside each other.

4. A permanent magnet brushless motor according to claim 1, characterized in that, The permanent magnet is a monolithic structure without splicing.

5. A permanent magnet brushless motor according to claim 1, wherein, The main housing is generally cylindrical and the outer diameter of the main housing is 12 mm to 46 mm.

6. A permanent magnet brushless motor according to claim 1, characterized in that, The air gap between the permanent magnet and the armature assembly is 0.05 mm to 0.2 mm.

7. A permanent magnet brushless motor according to claim 1, characterized in that, The housing is made of 2024 aluminum alloy by powder metallurgy process; Alternatively, the housing is made of 6061 aluminum alloy by powder injection process.

8. A permanent magnet brushless motor according to claim 1, wherein The end cover abuts against the inner ring of the first bearing.

9. A permanent magnet brushless motor according to claim 1, characterized in that, The stator module further includes a preloading spring. The rotating shaft passes through the preloading spring. One end of the preloading spring abuts against the boss on the base and the other end abuts against the outer ring of the second bearing.

10. A permanent magnet brushless motor according to claim 1, wherein, The stator module further includes a gasket and a snap ring. The second end of the rotating shaft passes through the inner ring of the second bearing and the part of the rotating shaft passing through the second bearing is installed with the gasket and the snap ring. The gasket abuts against the inner ring of the second bearing. The snap ring presses the gasket against the inner ring of the second bearing.

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