CN215498467U - Outer rotor permanent magnet direct current brushless motor and fan applying same - Google Patents

Abstract

The utility model discloses an outer rotor permanent magnet brushless direct current motor and a fan applied by the same, relates to the technical field of three-phase brushless direct current motors, and can solve the problem that the processing, assembly and cost of the motor are difficult to optimize. The permanent magnet outer rotor comprises a permanent magnet ring and a bearing disc which are integrally formed by magnetic plastics, and further comprises a magnetic conduction ring, so that the permanent magnet outer rotor can be used as a part of a motor shell and is matched with a conventional excitation stator assembly in a coaxial rotating mode with a middle shaft, the outer rotor, the middle shaft and an inner stator can be directly assembled to form a motor, the motor shell is omitted, materials, processing and assembling of the motor shell are correspondingly omitted, even a magnetic conduction component is omitted, and the motor is simplified in process, improved in processing efficiency and further reduced in cost. The motor is widely applied, for example, fan blades are arranged outside the permanent magnet outer rotor to form a fan, so that the processing, assembly and cost of the fan are further optimized.

Description

Outer rotor permanent magnet direct current brushless motor and fan applying same

Technical Field

The utility model relates to the technical field of three-phase direct current brushless motors, in particular to an outer rotor permanent magnet direct current brushless motor and a fan applying the same.

Background

The motor is an electromagnetic device for realizing the conversion or transmission of electric energy according to the law of magnetic induction. The current brushless direct current motor mainly comprises a permanent magnet assembly and an excitation assembly. The excitation assembly is a three-phase winding structure, and the windings are started by currents with different phases by utilizing an electric control technology, so that the excitation assembly forms a rotating magnetic field to push the permanent magnet assembly.

The prior art dc brushless motor includes a plurality of components such as an upper housing, a lower housing, a magnetic ring, a stator core, a winding, a circuit board, and a motor shaft. In the brushless DC motor, the magnetic field of the permanent magnet has one side inside the phase and one side outside the phase, and the two are distributed uniformly. This prevents the magnetic field generated by the excitation assembly from acting fully on the magnetic field of the permanent magnet assembly. Therefore, it is necessary to provide a ferrous structure, which is magnetically permeable, in the outer circumferential direction of the permanent magnet pole. One part of the motor, such as chinese patent CN202019248U, discloses a rotor of a dc motor for a decorative fan, which includes a circular iron sleeve, a permanent magnet ring integrally processed into a ring by using a permanent magnet material is disposed in the circular iron sleeve, and the permanent magnet ring and the circular iron sleeve are bonded together by glue. The outer rotor motor improves the magnetic field of the permanent magnet ring through the iron sleeve, so that the magnetic field is concentrated on the inner rotor. The other direct current motor directly adopts an iron shell to improve the magnetic field of the outer rotor

If a non-magnetic conductive shell such as plastic is adopted, a steel outer ring conductor needs to be arranged on a magnetic ring; if a magnetic conduction shell such as steel is adopted, the motor rotor is heavy, the starting is slow, and the energy consumption is high; meanwhile, the development of the motor is mature at present, parts and structures are fixed, the processing and assembly are difficult to further simplify, and the cost is reduced.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects in the prior art, the utility model mainly aims to provide an outer rotor permanent magnet direct current brushless motor which can further simplify the processing and the assembly and reduce the cost.

The utility model also provides a fan which can be directly formed by installing fan blades on the motor so as to obtain a fan which is further optimized in processing, installation and cost.

In order to achieve the above object, the present invention adopts the following technical solutions.

An outer rotor permanent magnet brushless DC motor comprises a permanent magnet outer rotor, a middle shaft and an excitation stator component;

the permanent magnet outer rotor comprises a permanent magnet ring and a bearing disc which are formed by magnetic plastics in an integrated mode; the permanent magnetic outer rotor is arranged on the middle shaft through a bearing disc, and the excitation stator assembly is arranged on the middle shaft so that the permanent magnetic outer rotor and the excitation stator assembly rotate relatively coaxially with the middle shaft; the permanent magnet ring is provided with at least two permanent magnet poles along the inner circumferential direction, and the excitation stator assembly is matched with the excitation pole of the permanent magnet poles so that the excitation pole drives the permanent magnet outer rotor and the excitation stator assembly to rotate under the electrification and magnetization.

The motor scheme preferably includes that the bearing disc is provided with a first central hole, and the middle shaft is coaxially and fixedly connected to the permanent magnet outer rotor through the first central hole; the excitation stator assembly is coaxially and rotatably arranged on the middle shaft.

The scheme of the motor can be further selected, the middle shaft is provided with a groove structure along the circumferential direction, and the permanent magnet outer rotor is fixed in the groove structure in a forming mode.

The above motor scheme is further optional, and a strip-shaped boss extending along the axial direction of the middle shaft is arranged in the groove structure.

The above-mentioned motor scheme is further optional, still include first antifriction bearing and second antifriction bearing; the excitation stator assembly is provided with a second center hole, outer rings of the first rolling bearing and the second rolling bearing are respectively coaxially and fixedly connected to two axial sides of the second center hole, and the middle shaft is fixedly connected to inner rings of the first rolling bearing and the second rolling bearing.

The permanent magnet outer rotor further comprises a magnetic conduction ring, the magnetic conduction ring is located on the outer side of the permanent magnet ring, and the permanent magnet ring, the bearing disc and the magnetic conduction ring are connected in a magnetic-plastic integrated forming mode.

The above motor scheme is further optional, the permanent magnet ring is a hard magnet structure formed by solidifying an adhesive after magnetizing magnetic powder; the magnetic conductive ring and the bearing plate are soft magnetic structures formed by solidifying uncured magnetic powder of the adhesive after reverse demagnetization so as to form a permanent magnetic ring, the bearing plate and the magnetic conductive ring which are molded integrally.

The above-mentioned motor scheme is preferred, still includes the shell body, the shell body is located permanent magnetism ring and for bearing the axial one end of dish to cooperate with the permanent magnetism outer rotor and enclose the cavity that is used for setting up excitation stator subassembly. More specifically, the permanent magnet ring and the magnetic conduction ring are cylindrical ring shapes, and the periphery of the bearing disc is connected to one axial end of the permanent magnet ring in a magnetic-plastic integrated forming mode; the outer shell is fixedly connected to the excitation stator assembly and located at the other axial end of the permanent magnet ring.

Preferably, in the above motor scheme, the excitation stator assembly includes a stator core and a three-phase winding wound around the stator core to form at least 3n excitation poles; the permanent magnet ring is correspondingly provided with 2n permanent magnet poles, wherein n is a positive integer, so that the permanent magnet outer rotor and the excitation stator assembly are pushed under the condition that the excitation poles are electrified and magnetized.

A fan, comprising: the fan blades and the outer rotor permanent magnet direct current brushless motor; the fan blades are fixedly arranged on the motor and rotate along with the permanent magnet outer rotor.

Compared with the prior art, the utility model has the following beneficial effects:

(1) the outer rotor permanent magnet direct current brushless motor comprises a permanent magnet ring and a bearing disc which are integrally formed by magnetic molding, so that the permanent magnet outer rotor can be used as a part of a motor shell and is coaxially and rotationally matched with a conventional excitation stator assembly, the outer rotor, a middle shaft and an inner stator can be directly assembled to form the motor, the motor shell is omitted, the motor shell material, the processing and the assembly are correspondingly omitted, and the simplification of the motor process, the improvement of the processing efficiency and the further reduction of the cost are realized; furthermore, the permanent magnetic ring, the magnetic conductive ring and the bearing disc can be molded integrally, so that the material, processing and assembly of the magnetic conductive part of the motor are reduced;

(2) the permanent magnet outer rotor is fixed with the middle shaft through magnetic-plastic integral forming, and the excitation stator assembly is provided with the rolling bearing matched with the middle shaft, so that the assembly process of the middle shaft and the outer rotor is omitted, the accuracy of the position relation of each magnetic pole and the middle shaft can be ensured in the magnetic-plastic forming process, and finally the accuracy of the rotational positioning between the excitation stator assembly and the permanent magnet outer rotor is ensured;

(3) the permanent magnet ring, the magnetic conduction ring and the bearing disc are molded in a magnetic-plastic mode, wherein the permanent magnet ring is provided with permanent magnet poles which can be pushed by an excitation stator assembly, the magnetic conduction ring restrains the magnetic field direction of each permanent magnet pole towards the inside of the motor, the bearing disc can realize the installation and protection functions of a motor shell, and the permanent magnet ring and the magnetic conduction ring are axially and accurately positioned and matched on the middle shaft, so that an outer rotor and an inner stator can be positioned in a high-precision mode.

(4) The fan blades of the fan can be directly arranged on the permanent magnet outer rotor or arranged on a middle shaft which follows the permanent magnet outer rotor. The purposes of simplifying the fan structure, improving the processing efficiency and reducing the cost are achieved.

The utility model will be further described with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic perspective view of an outer rotor permanent magnet brushless dc motor according to an embodiment of the present invention;

fig. 2 is a schematic cross-sectional exploded view of an outer rotor permanent magnet brushless dc motor according to an embodiment of the present invention;

fig. 3 is a schematic cross-sectional assembly diagram of an outer rotor permanent magnet brushless dc motor according to an embodiment of the present invention;

fig. 4 is a schematic top view of an outer rotor permanent magnet brushless dc motor according to an embodiment of the present invention;

fig. 5 is a schematic bottom view of a fan with an outer rotor permanent magnet dc brushless according to the present invention.

The reference signs are: 10. a permanent magnet outer rotor; 11. a permanent magnet ring; 12. a carrier tray; 13. a magnetic conductive ring; c10, permanent magnet poles; 121. a first central aperture; 20. exciting the stator assembly; 21. a stator core; 22. a winding; c20, a field pole; 211. a second central aperture; 30. a shaft is arranged in the middle; 31. a slot structure; 311. a strip-shaped boss; 41. a first rolling bearing; 42. a second rolling bearing; 50. an outer housing; 60. a fan blade.

Detailed Description

To better illustrate the objects, technical solutions and advantages of the present invention, the following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples. The following examples are intended to illustrate the utility model, but are not intended to limit the scope of the utility model.

As shown in fig. 1 to 4, the present invention relates to an outer rotor permanent magnet brushless dc motor. The brushless dc motor includes a permanent magnet outer rotor 10, a field stator assembly 20, a center shaft 30, and an outer housing 50. The permanent magnet outer rotor 10 comprises a permanent magnet ring 11, a bearing disc 12 and a magnetic conduction ring 13 which are formed by magnetic powder and adhesive in a magnetic-plastic integrated mode. The permanent magnet outer rotor 10 is coaxially arranged on the middle shaft 30 through the bearing plate 12, and the excitation stator assembly 20 is coaxially arranged on the middle shaft 30, so that the permanent magnet outer rotor 10 and the excitation stator assembly 20 can coaxially rotate relatively through the middle shaft 30. The permanent magnet ring 11 is a hard magnetic structure, and at least two permanent magnet poles c10 are arranged along the inner circumferential direction, and the magnetic field directions of adjacent permanent magnet poles c10 are opposite in the radial direction. The magnetic conductive ring 13 is of a soft magnetic structure so as to confine the magnetic field outside each permanent magnet pole c10 and strengthen the magnetic field inside each permanent magnet pole c 10. An exciter pole c20 is fitted to the permanent magnet pole c10 on the outside of the field stator assembly 20, so that the exciter pole c20 pushes the permanent magnet outer rotor 10 and the field stator assembly 20 under energization and magnetization. The permanent magnet outer rotor 10 is provided with a permanent magnet ring 11 on the inner side and a magnetic conductive ring on the outer side, and the permanent magnet outer rotor 10 is connected with the middle shaft 30 through a bearing plate 12 and matched with the excitation stator assembly 20 which is also connected with the middle shaft 30. The permanent magnet outer rotor 10 and the excitation stator assembly 20 realize the conversion of electric energy and rotational kinetic energy, and the permanent magnet outer rotor 10 and the outer shell 50 are matched to be used as the integral shell of the brushless dc motor. In the above-mentioned motor solution, preferably, the bearing disc 12 is provided with a first central hole 121, and the central shaft 30 is coaxially and fixedly connected to the permanent magnet outer rotor 10 through the first central hole 121. The excitation stator assembly 20 is coaxially and rotatably disposed on the center shaft 30. It is understood that, in other embodiments, the magnetic conductive ring may be a ring structure made of magnetic conductive material such as iron, cobalt, nickel, etc. and is sleeved outside the permanent magnet ring.

Referring to fig. 2 and 3, the structure of the outer rotor permanent magnet brushless dc motor of the present embodiment is specifically that the bearing disc 12 is provided with a first central hole 121. The middle shaft 30 is fixedly connected with the bearing disc 12 of the permanent magnet outer rotor 10 through the first central hole 121. The field stator assembly 20 includes a stator core 21 formed by laminating magnetic steels, and a three-phase winding 22 wound around the stator core 21. The stator core 21 is provided with a second center hole 211 in the axial direction, and the first rolling bearing 41 and the second rolling bearing 42 are respectively and fixedly provided on both sides of the second center hole 211 in the axial direction by press fit, so that the outer rings of the first rolling bearing 41 and the second rolling bearing 42 are fixed to the stator core 21. Referring to fig. 2, the explosion state of each component and the combination state of each component in fig. 3, it can be seen that the central shaft 30 can be axially press-fit and fixedly mounted to the inner rings of the first rolling bearing 41 and the second rolling bearing 42, so that the integrated central shaft 30 and the permanent magnet outer rotor 10 can be relatively rotatably disposed on the integrated rolling bearing and the excitation stator assembly 20 around the axis. The outer rotor permanent magnet dc brushless motor of the present embodiment can realize the arrangement of the permanent magnet outer rotor 10 and the center shaft 30 integrally and rotate at the same time, while the field stator assembly 20 is fixed for the installation of the motor. On the basis that the permanent magnet outer rotor 10 can be used for a motor part shell, each permanent magnet pole c10 on the permanent magnet outer rotor 10 can be positioned on the middle shaft 30 with high precision, the rolling bearing and the excitation stator assembly 20 can also be positioned on the middle shaft 30 with high precision, and finally, the gaps, the coaxiality and the like of each permanent magnet pole c10 and the excitation pole c20 are matched more precisely.

It is understood that in other embodiments, the relative rotation connection among the central shaft 30, the permanent magnet outer rotor 10 and the excitation stator assembly 20 is also implemented by fixedly arranging the outer ring of the rolling bearing on the bearing plate 12, coaxially and fixedly arranging the central shaft 30 on the stator core 21, and pressing and fixing the central shaft 30 on the inner ring of the rolling bearing. In this solution, the central shaft 30 and the field stator assembly 20 are fixed for installation of the motor, while the permanent magnet outer rotor 10 is the rotating part of the motor.

In this embodiment, regarding the fixing connection scheme between the permanent magnet outer rotor 10 and the central shaft 30, referring to fig. 2 and 3 again, the central shaft 30 is provided with a groove structure 31 along the circumferential direction, and a strip-shaped boss 311 extending along the axial direction of the central shaft 30 is arranged inside the groove structure 31. During the magnetic-plastic integral molding process of the permanent magnet outer rotor 10, the central shaft 30 is embedded into a molding die, and the bearing disc 12 is solidified on the central shaft 3. Specifically, the carrier plate 12 forms a first central hole 121 during magnetic molding, and the first central hole 121 fits the shape of the slot structure 31 and the shape of each strip-shaped boss 311, so that the permanent magnet outer rotor 10 and the central shaft 30 are fixed. When the excitation stator assembly 20 is powered on and drives the permanent magnet outer rotor 10 to rotate, the permanent magnet outer rotor 10 can drive the middle shaft 30 to rotate more firmly.

Referring to fig. 4, a scheme of matching the permanent magnet outer rotor 10 and the field stator assembly 20 of the outer rotor permanent magnet brushless dc motor according to the present embodiment is shown. The permanent magnet outer rotor 10 specifically, the permanent magnet outer rotor 10 has a circular ring structure, the inner side of the circular ring structure is a permanent magnet ring 11, and the outer side of the circular ring structure is a magnetic conductive ring 13. The permanent magnet ring 11 is uniformly provided with 8 permanent magnet poles c10 along the circumferential direction. One of the adjacent permanent magnet poles c10 is an inner S pole and an outer N pole, and the other is an inner N pole and an outer S pole. Specifically, the excitation stator assembly 20 has 12 teeth of the same specification uniformly arranged on the outer circumference of the stator core 21, the teeth are provided with winding grooves, the winding grooves are provided with windings, and each winding forms a three-phase winding 22. The windings and teeth cooperate to form the field pole c20, i.e., 12 field poles c20 in total. It can be seen that each phase of the three-phase winding 22 will generate a symmetric magnetic field in the energized state, the three-phase winding 22 forms a transformation of the magnetic field, while the permanent magnet outer rotor 10 has a magnetic field symmetry about the axial pairs of phases, and the difference in polarity of the permanent magnet outer rotor 10 and the three-phase winding 22 pushes the rotor to turn smoothly. In other embodiments, the field stator assembly 20 may also be provided with n greater than 4 schemes, such as 24 field poles c20, and correspondingly the permanent magnet ring 11 forms 16 permanent magnet poles c 10.

More specifically, the permanent magnet outer rotor 10 of the present embodiment is formed by magnetizing and curing a magnetic powder and a binder, and the cured permanent magnet ring 11 will form a hard magnetic structure, i.e. magnetizing again without fading the magnetic direction and the magnetic direction. The magnetizing magnetic direction and relative position are consistent with the position and magnetic direction of 8 magnetic poles. After the permanent magnet ring 11 is solidified, the adhesive of the magnetic conductive ring 13 is kept in a molten state, magnetic powder recovers magnetic field anisotropy through reverse magnetization, and the magnetic conductive ring is solidified in the anisotropic state, and the solidified magnetic conductive ring 13 does not show a magnetic direction and is of a soft magnetic structure. Similarly, after the permanent magnet ring 11 is solidified, the adhesive of the carrier plate 12 is kept in a molten state, and the magnetic powder is restored to magnetic field anisotropy by reverse magnetization and is solidified in an anisotropic state. The opposite magnetizing direction and the opposite position of the permanent magnet ring 11 are opposite to the position of 8 magnetic poles. Under the action of the magnetic conductive ring 13, the outer magnetic field of each permanent magnet pole c10 in the permanent magnet ring 11 passes through the inside of the magnetic conductive ring 13, so that the outer side of the permanent magnet outer rotor 10 does not have a magnetic core, and cannot attract articles made of materials such as iron, cobalt, nickel and the like. Alternatively, the outer side of the permanent magnet ring 11 exhibits weaker magnetism, in particular weaker with respect to the inner side. Due to the magnetic shielding effect of the magnetic conductive ring 13 on the permanent magnet ring 11, the inner magnetic field of each permanent magnet pole c10 in the permanent magnet ring 11 will be stronger, and the magnetic field interaction force will be larger when each permanent magnet pole c10 is pushed by the energized exciter pole c 20.

More specifically, the permanent magnet outer rotor 10 of the present embodiment includes a permanent magnet ring 11 and a magnetic conductive ring 13, wherein the permanent magnet ring 11 and the magnetic conductive ring 13 are cylindrical ring structures, the bearing disc 12 of the permanent magnet outer rotor 10 is a circular plate structure, and the permanent magnet ring 11, the bearing disc 12 and the magnetic conductive ring 13 together form a structure with one end open and the other end closed along the axial direction. The outer casing 50 is a square plate structure and is disposed at one end of the opening of the cylindrical ring structure, so that the outer casing 50 and the permanent magnet outer rotor 10 cooperate to form a cavity for disposing the excitation stator assembly 20 and the middle shaft 30. The dotted circle line in fig. 4 is a dividing line of the magnetic conductive ring 13 and the permanent magnet ring 11. The 8 division lines distributed in the circumferential direction indicate that the permanent magnet ring 11 is divided into 8 permanent magnet poles c 10. Wherein, the magnetic powder is ferrite supported by ball milling, the adhesive is nylon 12, and the permanent magnetic ring 11, the integrated magnetic conductive ring 13 and the bearing disc 12, and the bearing disc 12 and the middle shaft 30 are positioned in a single magnetic plastic molding process to be cured and molded.

The permanent magnet outer rotor 10 of the utility model is formed by integrally molding magnet and plastic into a cover-shaped structure. The cover surface of the cover-shaped structure is a bearing disc 12, the side wall surface of the cover-shaped structure is a permanent magnet ring 11 and a magnetic conduction ring 13, and the center of the cover surface of the cover-shaped structure is fixedly connected with a middle shaft 30. The permanent magnet outer rotor 10 of the present invention can be manufactured by the following processing method:

(1) the special mold is provided, and the mold comprises at least two mold split bodies which can be opened and closed, and the mold split bodies can form a mold cavity with a cover-shaped structure. The mold is further provided with a fitting hole for fixing the groove structure 31 of the center shaft 30 into the cavity of the mold and positioning it at a position corresponding to the central axis of the cover surface of the mold cavity. The middle shaft of the mould is provided with a cavity to prevent the orientation magnetizing device. A cooling device is arranged in the cover-shaped side surface of the mould close to the mould cavity for solidifying the permanent magnetic ring 11, and a heat preservation device is arranged outside the cover-shaped side surface and the cover surface of the mould cavity correspondingly for keeping other magnetic plastic materials of the mould cavity to be molten after the permanent magnetic ring 11 is solidified;

(2) mixing strontium barium ferrite powder, zinc ferrite powder, nylon 12, a silane coupling agent and a lubricant, fully stirring and drying, heating and melting the mixed powder by a double-screw extruder, and injecting the heated and melted mixed powder into a cavity of the die;

(3) and starting the magnetizing equipment to magnetize the molten material, wherein the magnetic poles of the magnetic powder in the molten material are rotated to be consistent with the magnetizing direction in the strong magnetic field, and a plurality of permanent magnetic poles c10 with opposite adjacent magnetic fields are formed in the circumferential direction. The molten adhesive is cooled and solidified by the inner cooling device on the side surface to form the permanent magnet ring 11 with a hard magnetic structure, and each permanent magnet pole c10 has a directional magnetic field after being formed and is not easy to demagnetize. Meanwhile, the magnetic plastic materials in the rest parts except the permanent magnetic ring 11 at the die cavity are kept in a molten state by utilizing heat preservation devices outside the side surface and the cover surface of the die;

(4) and switching the orientation magnetizing device to the reverse direction, demagnetizing the magnetic plastic material in the molten state, and recovering the magnetic anisotropy of the magnetic powder on a reverse demagnetizing magnetic field. The heat preservation device is closed again, the molten material after degaussing is cooled and solidified, and a magnetic conduction ring 13 with a soft magnetic structure is formed, the magnetic powder in the magnetic conduction ring is solidified in an anisotropic way, does not have a directional magnetic field and can be magnetized by an external magnetic field, and then the magnetic conduction can be realized. A groove structure 31 matched with the middle shaft 30 and a first central hole 121 matched with a strip-shaped boss 311 in the groove structure 31 are formed at the axial center of the cover surface of the mold cavity, so that the permanent magnet outer rotor 10 is fixed on the middle shaft 30 in a magnetic-plastic molding mode, and the middle shaft 30 and the permanent magnet outer rotor 10 of the motor are integrally and firmly rotated.

The outer rotor permanent magnet direct current brushless motor provided by the embodiment of the utility model has an identification method. The method is characterized in that the outer permanent magnet rotor 10 as a part of the motor shell does not form magnetic force to soft magnetic materials such as iron cobalt nickel on the outer periphery of the side surface, and forms strong magnetic force to the soft magnetic materials such as iron cobalt nickel on the inner periphery of the side surface.

The outer rotor permanent magnet brushless direct current motor in the embodiment of the utility model has an assembling method. The method comprises the following steps: (1) the first rolling bearing 41 and the second rolling bearing 42 are respectively installed at the two axial ends of the second center hole 211 of the stator core 21 in a pressing mode; (2) the stator core 21 and the outer housing 50 are fixed by bolts; (3) the integrated structure of the permanent magnet outer rotor 10 and the center shaft 30 is fixed to the integrated structure of the stator core 21 and the outer case 50 by inserting and attaching the center shaft 30 to the first rolling bearing 41 and the second rolling bearing 42. The assembly of the motor is thus completed.

As shown in fig. 5, the present invention further provides a fan, to which the outer rotor permanent magnet brushless dc motor of the above embodiment is applied. In the embodiment of the present fan, the fan further includes fan blades 60, the fan blades 60 are fixedly connected to the central shaft 30, when the motor is powered on and operated, the excitation stator assembly 20 generates a rotating magnetic force to push the permanent magnet outer rotor 10 to rotate, then the permanent magnet outer rotor 10 drives the central shaft 30 to rotate, and the central shaft 30 drives the fan blades 60 to rotate to form a fan. In other embodiments, the bearing disc 12 of the permanent magnet outer rotor 10, the bearing disc 12 is provided with screw holes, the fan blades 60 are fixed on the bearing disc 12 through the screw holes, and the fan blades 60 rotate along with the rotation of the permanent magnet outer rotor 10 when in use. The fan is fixed through mounting holes at four corners of the outer case 50.

The foregoing embodiments have been described primarily for the purposes of illustrating the general principles, and features and advantages of the utility model. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the utility model as claimed.

Claims (10)

1. An outer rotor permanent magnet direct current brushless motor is characterized by comprising a permanent magnet outer rotor (10), a middle shaft (30) and an excitation stator assembly (20);

the permanent magnet outer rotor (10) comprises a permanent magnet ring (11) and a bearing disc (12) which are formed by magnetic plastic in an integrated mode;

the permanent magnet outer rotor (10) is arranged on the middle shaft (30) through the bearing disc (12), and the excitation stator assembly (20) is arranged on the middle shaft (30) so that the permanent magnet outer rotor (10) and the excitation stator assembly (20) can rotate relatively coaxially with the middle shaft (30);

the permanent magnet ring (11) is provided with at least two permanent magnet poles (c10) along the inner circumferential direction, and the excitation stator assembly (20) is matched with an excitation pole (c20) of the permanent magnet pole (c10) so that the excitation pole (c20) is electrified and magnetized to drive the permanent magnet outer rotor (10) and the excitation stator assembly (20) to rotate mutually.

2. The outer rotor permanent magnet brushless dc motor according to claim 1, wherein the carrier disc (12) is provided with a first central hole (121), and the center shaft (30) is coaxially and fixedly connected to the permanent magnet outer rotor (10) through the first central hole (121); the excitation stator assembly (20) is coaxially and rotatably arranged on the middle shaft (30).

3. The outer rotor permanent magnet brushless dc motor according to claim 2, wherein the center shaft (30) is provided with a groove structure (31) along a circumferential direction, and the permanent magnet outer rotor (10) is fixed in the groove structure (31) in a forming manner.

4. The outer rotor permanent magnet brushless dc motor according to claim 3, wherein a bar-shaped boss (311) extending in the axial direction of the center shaft (30) is provided inside the groove structure (31).

5. The outer rotor permanent magnet brushless dc motor of claim 2, further comprising a first rolling bearing (41) and a second rolling bearing (42); the excitation stator assembly (20) is provided with a second center hole (211), outer rings of the first rolling bearing (41) and the second rolling bearing (42) are respectively coaxially and fixedly connected to two axial sides of the second center hole (211), and the middle shaft (30) is fixedly connected to inner rings of the first rolling bearing (41) and the second rolling bearing (42).

6. The outer rotor permanent magnet brushless dc motor of claim 1, wherein the permanent magnet outer rotor (10) further comprises a magnetic conductive ring (13), the magnetic conductive ring (13) is located outside the permanent magnet ring (11), and the permanent magnet ring (11), the carrying disc (12) and the magnetic conductive ring (13) are connected by magnetic-plastic integral molding.

7. The external rotor permanent magnet brushless dc motor according to claim 6, wherein the permanent magnet ring (11) is a hard magnetic structure formed by magnetizing magnetic powder and then curing an adhesive; the magnetic conductive ring (13) and the bearing disc (12) are soft magnetic structures formed by solidifying uncured magnetic powder of an adhesive after reverse demagnetization so as to form a permanent magnetic ring (11), the bearing disc (12) and the magnetic conductive ring (13) which are molded into a whole.

8. The outer rotor permanent magnet brushless dc motor according to claim 1, further comprising an outer housing (50), wherein the outer housing (50) is located at an axial end of the permanent magnet ring (11) with respect to the carrier plate (12) and cooperates with the permanent magnet outer rotor (10) to define a cavity for positioning the excitation stator assembly (20).

9. The outer rotor permanent magnet brushless dc motor of claim 1, wherein the field stator assembly (20) comprises a stator core (21) and three-phase windings (22) wound on the stator core (21) to form at least 3n field poles (c 20); the permanent magnet ring (11) is correspondingly provided with 2n permanent magnet poles (c10), wherein n is a positive integer, so that the excitation pole (c20) is electrified and magnetized to push the permanent magnet outer rotor (10) and the excitation stator assembly (20).

10. A fan, comprising: fan blades (60), and an outer rotor permanent magnet brushless dc motor according to any of claims 1 to 9, wherein the fan blades (60) are fixedly arranged on the motor and rotate with the permanent magnet outer rotor (10).

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