CN215378582U

CN215378582U - Brushless DC motor and dust catcher

Info

Publication number: CN215378582U
Application number: CN202121630289.7U
Authority: CN
Inventors: 葛梦; 李文瑞; 杨雄
Original assignee: Midea Welling Motor Technology Shanghai Co Ltd
Current assignee: Midea Welling Motor Technology Shanghai Co Ltd
Priority date: 2021-07-16
Filing date: 2021-07-16
Publication date: 2021-12-31
Anticipated expiration: 2031-07-16

Abstract

The utility model discloses a brushless direct current motor and a dust collector, wherein the brushless direct current motor comprises a motor stator and a motor rotor, the motor stator comprises a stator iron core, and a stator inner hole is formed in the stator iron core. The motor rotor is arranged in the stator inner hole, and the ratio of the diameter of the stator inner hole to the outer diameter of the stator core is greater than or equal to 0.31 and less than or equal to 0.42. The technical scheme of the utility model can improve the operation efficiency of the motor.

Description

Brushless DC motor and dust catcher

Technical Field

The utility model relates to the technical field of motors, in particular to a brushless direct current motor and a dust collector.

Background

With the development of science and technology and the progress of society, the living standard of people is gradually improved, and more families use dust collectors at present, because the operating characteristics and the volume limitation of dust collectors, the key parts of the brushless direct current motor are required to have the characteristics of higher power density, high rotating speed, high efficiency, low cost and the like, and in the prior art, the brushless direct current motor has higher weight and low efficiency and cannot meet the requirements of products.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide a brushless direct current motor, aiming at improving the operation efficiency of the motor.

In order to achieve the above object, the present invention provides a brushless dc motor, comprising:

the motor stator comprises a stator core, wherein a stator inner hole is formed in the stator core; and

the motor rotor is arranged in the stator inner hole;

the ratio of the diameter of the stator inner hole to the outer diameter of the stator core is greater than or equal to 0.31 and less than or equal to 0.42.

Optionally, the outer diameter of the stator core is greater than or equal to 32mm and less than or equal to 36 mm.

Optionally, the stator core includes a stator yoke and at least three stator teeth, each of the stator teeth is connected to an inner side of the stator yoke and is uniformly spaced in a circumferential direction of the stator yoke, and the stator inner hole is located at an inner side of each of the stator teeth.

Optionally, one end of each stator tooth, which is close to the axis of the brushless dc motor, is provided with a pole shoe, one side of the pole shoe, which is close to the stator inner hole, is provided with at least one groove, and the groove extends along the axial direction of the stator core.

Optionally, the pole shoes are arranged symmetrically, and the grooves on the pole shoes are arranged symmetrically about the symmetry axis of the pole shoes.

Optionally, the motor rotor comprises a rotating shaft and an annular permanent magnet sleeved outside the rotating shaft; the width of an air gap between the stator core and the annular permanent magnet is larger than or equal to 1.2mm and smaller than or equal to 1.6 mm.

Optionally, the thickness of the annular permanent magnet is greater than or equal to 2.4mm, and less than or equal to 2.85 mm.

Optionally, the motor rotor further includes a fastening sleeve, and the fastening sleeve is sleeved outside the annular permanent magnet.

Optionally, the fastening sleeve is made of stainless steel or carbon fiber.

The utility model also provides a dust collector which comprises the brushless direct current motor.

According to the technical scheme, when the ratio of the diameter of the inner hole of the stator to the outer diameter of the stator core is in the range of 0.31-0.42, the using amount of the stator core can be optimized, copper loss, iron loss and eddy current loss can be well balanced, the electromagnetic loss of the motor is reduced, and the brushless direct current motor can achieve high working efficiency at high rotating speed, so that the brushless direct current motor can achieve high power density, and the requirements of small-size and light-weight design are met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a brushless dc motor according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a brushless DC motor according to another embodiment of the present invention;

fig. 3 is a schematic structural diagram of a brushless dc motor according to another embodiment of the present invention;

FIG. 4 is a graph illustrating the efficiency of a motor with increasing air gap size according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a brushless DC motor according to yet another embodiment of the present invention;

FIG. 6 is a cross-sectional view taken at X-X in FIG. 5;

fig. 7 is a graph showing the efficiency of the brushless dc motor according to the embodiment of the present invention as the protrusion height of the end of the annular permanent magnet increases compared to the end surface of the stator core.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				100	Brushless DC motor	115	Stator bore
10	Motor stator	12	Winding coil
				11	Stator core	20	Motor rotor
111	Stator yoke	21	Rotating shaft
				112	Stator tooth	22	Ring-shaped permanent magnet
113	Pole shoe	23	Fastening sleeve
				114	Groove	30	Air gap

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture, and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout is to include three juxtapositions, exemplified by "A and/or B," including either the A or B arrangement, or both A and B satisfied arrangement. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The utility model provides a brushless direct current motor which is used for a dust collector, a blower or other living electric appliances needing the motor.

In an embodiment of the present invention, referring to fig. 1, the brushless dc motor 10 includes a motor stator 10 and a motor rotor 20, the motor stator 10 includes a stator core 11, and the stator core 11 is formed with a stator inner hole 115. The motor rotor 20 is disposed in the stator inner hole 115, and a ratio of a diameter (see D1 in fig. 1) of the stator inner hole 115 to an outer diameter (see D2 in fig. 1) of the stator core 11 is greater than or equal to 0.31 and less than or equal to 0.42. That is, the ratio of the inner diameter to the outer diameter of stator core 11 is greater than or equal to 0.31 and less than or equal to 0.42.

In the present embodiment, when the motor rotor 20 is mounted in the stator bore 115, the outer circumferential surface of the motor rotor 20 is spaced from the inner wall surface of the stator bore 115 to form the air gap 30 between the motor rotor 20 and the inner wall surface of the stator bore 115. The stator core 11 may be formed by stacking a plurality of stator laminations in the axial direction, or may adopt other structures. The ratio of the diameter of the stator inner bore 115 to the outer diameter of the stator core 11 is greater than or equal to 0.31, and less than or equal to 0.42 may be specifically 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, or 0.42.

According to the technical scheme, when the ratio of the diameter of the inner hole 115 of the stator to the outer diameter of the stator core 11 is in the range of 0.31-0.42, the using amount of the stator core 11 can be optimized, copper loss, iron loss and eddy current loss can be well balanced, the electromagnetic loss of the motor is reduced, and the brushless direct current motor 10 can achieve high working efficiency at high rotating speed, so that the brushless direct current motor 10 can obtain higher power density, and the requirement of small-size and light-weight design is met.

In one embodiment, the outer diameter of the stator core 11 is greater than or equal to 32mm and less than or equal to 36 mm. Set up when 32mm to 36 mm's scope through the external diameter with stator core 11, can satisfy the temperature rise requirement, guarantee that brushless DC motor 10's performance is better, also can avoid leading to the too big condition of brushless DC motor 10's overall dimension because of stator core 11's external diameter is too big, make brushless DC motor 10's overall dimension less, be favorable to reducing brushless DC motor 10's whole volume and weight, realize small-size lightweight demand, still be favorable to improving motor power density. Specifically, the outer diameter of the stator core 11 may be 32mm, 23.5mm, 33mm, 33.5mm, 34mm, 34.5mm, 35mm, 35.5mm, 36mm, or the like. Of course, in other embodiments, the outer diameter of the stator core 11 may be less than 32mm or greater than 36 mm.

In one embodiment, the stator core 11 includes a stator yoke portion 111 and at least three stator teeth 112, each stator tooth 112 is connected to the inner side of the stator yoke portion 111 and is uniformly spaced in the circumferential direction of the stator yoke portion 111, and the stator inner holes 115 are located on the inner side of each stator tooth 112. Namely, the central included angle between two adjacent stator teeth 112 is 120 °, so that the structure is simple, the whole volume and weight of the brushless dc motor 10 are reduced, and the requirements of small size and light weight are met. The pole shoe 113, the stator teeth 112 and the stator yoke 111 may be integrally formed or may be separately formed and then spliced or welded together.

Referring to fig. 2, in an embodiment, a pole shoe 113 is disposed at an end of each stator tooth 112 close to the axis of the brushless dc motor 10, and at least one groove 114 is disposed at a side of the pole shoe 113 close to an inner hole 115 of the stator, where the groove 114 extends along an axial direction of the stator core 11. Specifically, the plurality of pole shoes 113 are spaced in the circumferential direction of the stator yoke portion 111 to form a stator gap between two adjacent pole shoes 113, each pole shoe 113 has an arc shape extending along the circumferential direction of the stator yoke portion 111, inner sides (sides close to the axis of the stator core 11) of the plurality of pole shoes 113 collectively form a stator inner hole 115, the stator inner hole 115 is used for mounting the electric motor rotor 20, and when the electric motor rotor 20 is mounted in the stator inner hole 115, an outer circumferential surface of the electric motor rotor 20 is spaced from inner side surfaces of the pole shoes 113 to form the air gap 30 between the electric motor rotor 20 and the pole shoes 113. The notch of the groove 114 faces the axis of the stator core 11, and two ends of the groove 114 in the axial direction of the stator core 11 are disposed in a penetrating manner, that is, one end of the groove 114 penetrates through one end surface of the stator core 11, and the other end penetrates through the other end surface of the stator core 11. Of course, in other embodiments, the pole piece 113 may have a straight strip shape or a folded edge shape. The stator core 11 may be formed by stacking a plurality of stator laminations in the axial direction, or may adopt other structures, which is not limited in the present invention. In addition, the pole shoe 113, the stator teeth 112, and the stator yoke 111 may be integrally formed or may be separately formed and then spliced or welded together.

Through being equipped with at least one recess 114 in pole shoe 113 one side that is close to stator core 11 axis, and make recess 114 along stator core 11's axial extension, so be equivalent to increased stator core 11 in the quantity of the stator clearance on circumference to when being used for brushless DC motor 10 with stator core 11, can improve air gap 30 magnetic conductance harmonic number, weaken the harmonic component, thereby reduce the eddy current loss that the harmonic arouses, promote motor operating efficiency. And the risk of overhigh heat productivity of the magnet due to eddy current loss can be reduced, so that the risk of demagnetization of the magnet can be reduced.

In one embodiment, the pole pieces 113 are symmetrically arranged, and the grooves 114 on the pole pieces 113 are symmetrically arranged about the symmetry axis of the pole pieces 113. Specifically, the symmetry axis of the pole shoe 113 extends in the radial direction of the stator core 11, i.e., the symmetry axis of the pole shoe 113 is substantially perpendicular to the axis of the stator core 11. When the grooves 114 on the pole shoes 113 are symmetrically arranged about the symmetry axis of the pole shoes 113, that is, the pole shoes 113 after the grooves 114 are arranged are still symmetrically arranged, so that the air gap 30 is relatively uniform, which is beneficial to reducing the noise of the brushless dc motor 10.

In one embodiment, each pole piece 113 is provided with a groove 114, the grooves 114 are located on the symmetry axis of the pole piece 113, and the shapes of the grooves 114 are symmetrically arranged about the symmetry axis of the pole piece 113. So set up, improve air gap 30 magnetic conductance harmonic number through recess 114, when weakening the harmonic component, can also make the quantity of recess 114 less, the shaping of being convenient for.

Referring to fig. 3, in another embodiment, each pole piece 113 is provided with at least two grooves 114, and all the grooves 114 on each pole piece 113 are symmetrically distributed about the symmetry axis of the pole piece 113. I.e., the number of grooves 114 on each pole piece 113 is even, all the grooves 114 on each pole piece 113 are symmetrically distributed about the axis of symmetry of the pole piece 113; when the number of the grooves 114 on each pole piece 113 is odd, one groove 114 on each pole piece 113 is located on the symmetry axis of the pole piece 113, and the rest grooves 114 are symmetrically distributed about the symmetry axis of the pole piece 113. In the present embodiment, two grooves 114 are disposed on each pole piece 113, and the two grooves 114 on each pole piece 113 are symmetrically distributed about the symmetry axis of the pole piece 113. So set up, can further improve air gap 30 magnetic conductance harmonic number, weaken the harmonic component to reduce the eddy current loss that the harmonic arouses, promote motor operating efficiency.

Referring to fig. 2 or fig. 3, in an embodiment, the groove 114 is polygonal or arc-shaped. Specifically, when the shape of the groove 114 is a polygon, that is, the groove wall of the groove 114 is formed into a multi-step flanged shape in the circumferential direction of the stator yoke 111, for example, the groove wall of the groove 114 is formed into a two-step flanged shape in the circumferential direction of the stator yoke 111 (that is, the groove 114 has two groove walls connected in the circumferential direction of the stator yoke 111), a three-step flanged shape (that is, the groove 114 has three groove walls connected in sequence in the circumferential direction of the stator yoke 111), a four-step flanged shape (that is, the groove 114 has four groove walls connected in sequence in the circumferential direction of the stator yoke 111), or more flanged shapes. The groove wall of the groove 114 is in a three-segment folded edge shape in the circumferential direction of the stator yoke 111, and when any two groove walls connected in the groove 114 are vertical, the groove 114 is rectangular. The shape of the groove 114 is an arc shape, that is, the groove wall of the groove 114 is in a concave arc shape that is recessed in a direction away from the axis of the stator core 11 in the circumferential direction of the stator yoke portion 111. When the arrangement is adopted, the effects of increasing the magnetic conductance harmonic times of the air gap 30 and weakening harmonic components can be better realized.

Referring to fig. 1, 2 or 3, in an embodiment, a distance between two adjacent pole shoes 113 on the stator core 11 (see S1 in fig. 1) is greater than or equal to 2.5mm and less than or equal to 5 mm. The plurality of pole shoes 113 are spaced in a circumferential direction of the stator yoke portion 111 to form a stator gap between adjacent two pole shoes 113, i.e., a width of the stator gap is greater than or equal to 2.5mm and less than or equal to 5 mm. Each pole shoe 113 has an arc shape extending along the circumferential direction of the stator yoke 111, the inner sides (the sides close to the axis of the stator core 11) of the pole shoes 113 jointly form a stator inner hole 115, the electric motor rotor 20 is installed in the stator inner hole 115, and the outer circumferential surface of the electric motor rotor 20 is spaced from the inner side surfaces of the pole shoes 113 to form an air gap 30 between the electric motor rotor 20 and the pole shoes 113. When setting up the interval between two adjacent pole shoes 113 on stator core 11 in 2.5mm to 5 mm's within range, can avoid influencing the downline because of the clearance undersize between two adjacent pole shoes 113, and can guarantee to make the eddy current loss less, be favorable to promoting brushless DC motor 10's operating efficiency, make brushless DC motor 10 can obtain higher power density, reach the demand of small-size lightweight design. The distance between two adjacent pole shoes 113 on the stator core 11 may be specifically 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5 mm. Of course, in other embodiments, the distance between two adjacent pole shoes 113 on the stator core 11 can be less than 2.5mm or more than 5 mm.

In one embodiment, the motor rotor 20 includes a rotating shaft 21 and an annular permanent magnet 22 sleeved outside the rotating shaft 21; the width of the air gap 30 between the stator core 11 and the annular permanent magnet 22 (refer to S2 in fig. 1) is greater than or equal to 1.2mm and less than or equal to 1.6 mm. Specifically, the brushless dc motor 10 can obtain high efficiency when the air gap 30 is large, but the use amount of copper wires is increased sharply when the air gap 30 is too large, and the winding temperature rise performance is not good when the current density is increased due to the reduction of the slot area and the increase of the slot area of the air gap 30. When the width of the air gap 30 is set within the range of 1.2mm to 1.6mm, on the basis of ensuring good winding temperature rise performance, the air gap 30 harmonic magnetic field generated by the fundamental wave and time harmonic current of the winding coil 12 is reduced, the armature reaction influence of the winding coil 12 is reduced, and the eddy current loss and the iron loss of the winding coil 12 are greatly reduced, so that the effect of improving the efficiency is achieved, and the motor efficiency is kept at a high value (refer to fig. 4, fig. 4 is a change curve of the motor efficiency along with the size of the air gap 30).

In one embodiment, the thickness of the ring-shaped permanent magnet 22 (see S3 in fig. 2) is greater than or equal to 2.4mm and less than or equal to 2.85 mm. Therefore, the output performance requirement of the brushless direct current motor 10 can be better met, the condition that the overall size of the brushless direct current motor 10 is overlarge due to the fact that the annular permanent magnet 22 is too thick can be avoided, the design requirement of small size and light weight can be better met, and the condition that the annular permanent magnet 22 is demagnetized can be avoided. The thickness of the annular permanent magnet 22 may be 2.4mm, 2.45mm, 2.5mm, 2.55mm, 2.6mm, 2.65mm, 2.7mm, 2.75mm, 2.8mm, 2.85mm, or the like. Of course, in other embodiments, the thickness of the ring-shaped permanent magnet 22 may be less than 2.4mm or greater than 2.85 mm.

In one embodiment, the motor rotor 20 further includes a fastening sleeve 23, and the fastening sleeve 23 is sleeved outside the annular permanent magnet 22. Like this through locating the adapter sleeve 23 cover outside annular permanent magnet 22, can tie annular permanent magnet 22 through adapter sleeve 23 to reduce annular permanent magnet 22 fracture risk when motor rotor 20 high-speed operation, promote brushless DC motor 100's reliability and life-span.

In one embodiment, the fastening sleeve 23 is made of stainless steel or carbon fiber. That is, the fastening sleeve 23 is made of a non-magnetic material, so that the fastening sleeve 23 can be prevented from changing the magnetism of the annular permanent magnet 22, and the stability of the magnetic field in the brushless dc motor 10 can be ensured.

For ease of installation positioning, in one embodiment, the stator yoke 111 is annular, specifically, the stator yoke 111 is closed annular, and the stator yoke 111 may be annular or polygonal. Of course, in other embodiments, the stator yoke 111 may be comprised of multiple structures.

In one embodiment, the stator yoke 111 has a polygonal shape, and the stator teeth 112 are connected to straight sides of the stator yoke 111. By the arrangement, the included angle between the stator teeth 112 and the straight edge of the stator yoke portion 111 is approximately 90 degrees, so that the space between the stator teeth 112 and the straight edge of the stator yoke portion 111 is large, the winding space of the winding coil 12 is increased, the slot filling rate of the motor can be improved, and the performance of the motor is improved.

In one embodiment, the pole piece angle (see included angle a in fig. 2) of each pole piece 113 is greater than or equal to 89.5 ° and less than or equal to 95 °. When the pole shoe angle of each pole shoe 113 is set to be within the range of 89.5 ° to 95 °, the back electromotive force of the brushless dc motor 10 can be made higher, so that the iron loss is smaller, the operation efficiency is higher, and the influence on the offline caused by the excessively small gap between the pole shoes 113 on two adjacent stator teeth 112 can be avoided. The pole shoe angle of each pole shoe 113 may be specifically 89.5 °, 90 °, 90.5 °, 91 °, 91.5 °, 92 °, 92.5 °, 93 °, 93.5 °, 94 °, 94.5 °, or 95 °. Of course, in other embodiments, the pole piece angle of each pole piece 113 may be less than 89.5 ° or greater than 95 °.

Referring to fig. 5 and 6, in an embodiment, the motor rotor 20 includes a rotating shaft 21 and an annular permanent magnet 22 sleeved outside the rotating shaft 21, and a protruding height (see H in fig. 6) of the annular permanent magnet 22 relative to an end surface of the stator core 11 is greater than or equal to 0.5mm and less than or equal to 3 mm. That is, at least one end of the annular permanent magnet 22 protrudes out of the end surface of the stator core 11, and when only one end of the annular permanent magnet 22 protrudes out of the end surface of the stator core 11, the protruding height of the end of the annular permanent magnet 22 is greater than or equal to 0.5mm and less than or equal to 3 mm. When both ends of the annular permanent magnet 22 protrude from the corresponding end surfaces of the stator core 11, the sum of the protruding heights of both ends of the annular permanent magnet 22 is greater than or equal to 0.5mm and less than or equal to 3 mm. Specifically, the protrusion height of the annular permanent magnet 22 from the end surface of the stator core 11 may be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, or the like. In order to improve the performance of the brushless dc motor, the material of the annular permanent magnet 22 may be neodymium iron boron.

Through with the terminal surface of the at least one end protrusion in stator core 11 of annular permanent magnet 22, can utilize the magnetic concentration effect of the protruding tip of annular permanent magnet 22, promote the air gap 30 magnetic density, thereby promote brushless DC motor 10 output performance, and the protrusion height that compares annular permanent magnet 22 in stator core 11's terminal surface is more than or equal to 0.5mm, and when being less than or equal to 3mm, make brushless DC motor 10's bulk loss less, efficiency is higher (refer to fig. 7), make brushless DC motor 10 can obtain higher power density, reach the demand of small-size lightweight design.

In one embodiment, one end of the ring-shaped permanent magnet 22 protrudes from the end surface of the stator core 11, and the other end is flush with the end surface of the stator core 11. That is, the protrusion height of one end of the annular permanent magnet 22 is greater than or equal to 0.5mm and less than or equal to 3mm compared with the corresponding end face of the stator core 11, and the protrusion height of the other end of the annular permanent magnet 22 is substantially 0 compared with the corresponding end face of the stator core 11. Therefore, the magnetic flux concentration effect of the protruding end part of the annular permanent magnet 22 can be utilized to improve the magnetic density of the air gap 30, so that the output performance of the brushless direct current motor 10 is improved.

In another embodiment, both ends of the ring-shaped permanent magnet 22 protrude from the corresponding end surfaces of the stator core 11. That is, the protrusion height of one end of the annular permanent magnet 22 is greater than or equal to 0.5mm and less than or equal to 3mm compared with the corresponding end face of the stator core 11, and the protrusion height of the other end of the annular permanent magnet 22 is greater than or equal to 0.5mm and less than or equal to 3mm compared with the corresponding end face of the stator core 11. With the arrangement, the magnetic flux density of the air gap 30 can be further improved by utilizing the magnetic flux gathering effect at the two ends of the annular permanent magnet 22, so that the output performance of the brushless direct current motor 10 is improved. And the efficiency is higher, so that the brushless direct current motor 10 can obtain higher power density, and the size and the weight of the brushless direct current motor 10 are further reduced. In one embodiment, the protruding heights of the two ends of the annular permanent magnet 22 are different from the corresponding end surfaces of the stator core 11. In another embodiment, the two ends of the annular permanent magnet 22 are protruded to the same height as the end surfaces corresponding to the stator core 11, that is, the two ends of the annular permanent magnet 22 are protruded to the same height, so that the magnetic concentration effect of the two ends of the annular permanent magnet 22 is approximately equivalent and relatively uniform.

The utility model further provides a dust collector, which comprises a shell, a wind wheel and a brushless direct current motor 10, wherein the specific structure of the brushless direct current motor 10 refers to the above embodiments, and the dust collector adopts all technical schemes of all the above embodiments, so that the dust collector at least has all beneficial effects brought by the technical schemes of the above embodiments, and details are not repeated herein. Wherein, the wind wheel is connected with the motor rotor 20 of the brushless DC motor 10, and the wind wheel and the brushless DC motor 10 are both arranged in the shell.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A brushless dc motor, comprising:

the motor rotor is arranged in the stator inner hole;

2. The brushless dc motor of claim 1, wherein the outer diameter of the stator core is greater than or equal to 32mm and less than or equal to 36 mm.

3. The brushless dc motor of claim 1, wherein the stator core includes a stator yoke and at least three stator teeth, each of the stator teeth being coupled to an inner side of the stator yoke and evenly spaced apart in a circumferential direction of the stator yoke, the stator bore being located on an inner side of each of the stator teeth.

4. A brushless dc motor according to claim 3, wherein each stator tooth has a pole piece at an end thereof adjacent to the axis of the brushless dc motor, and wherein the pole piece has at least one groove at a side thereof adjacent to the stator bore, the groove extending in the axial direction of the stator core.

5. A brushless DC motor according to claim 4, wherein the pole pieces are symmetrically arranged, the grooves in the pole pieces being symmetrically arranged about the axis of symmetry of the pole pieces.

6. The brushless dc motor according to any one of claims 1 to 5, wherein the motor rotor includes a rotating shaft and an annular permanent magnet fitted around the rotating shaft; the width of an air gap between the stator core and the annular permanent magnet is larger than or equal to 1.2mm and smaller than or equal to 1.6 mm.

7. The brushless dc motor of claim 6, wherein the thickness of the ring-shaped permanent magnet is greater than or equal to 2.4mm and less than or equal to 2.85 mm.

8. The brushless dc motor of claim 6, wherein the motor rotor further comprises a fastening sleeve, the fastening sleeve being disposed outside the annular permanent magnet.

9. The brushless dc motor of claim 8, wherein the fastening sleeve is made of stainless steel or carbon fiber.

10. A vacuum cleaner comprising a brushless dc motor according to any one of claims 1 to 9.