CN216122038U

CN216122038U - Improved brushless motor

Info

Publication number: CN216122038U
Application number: CN202121719847.7U
Authority: CN
Inventors: 周洛明; 严佑春
Original assignee: Guangdong Roman Technology Co Ltd
Current assignee: Dongguan Kede Precision Manufacturing Co ltd
Priority date: 2021-07-27
Filing date: 2021-07-27
Publication date: 2022-03-22
Anticipated expiration: 2031-07-27

Abstract

The utility model relates to an improved brushless motor, which comprises a frame, wherein an installation cavity is arranged in the frame, an installation cover is arranged on a spigot of the installation cavity, the installation cavity is provided with a first cavity and a second cavity, a stator assembly and a rotor assembly are arranged in the installation cavity, the second cavity is provided with an end face at the joint with the first cavity, vent holes are uniformly distributed on the end face, the rotor assembly comprises a rotating shaft, a magnetic ring, a front ball bearing, a rear ball bearing and an impeller, and two ends of the rotating shaft are respectively fixedly penetrated in the rear ball bearing and the front ball bearing; the magnetic ring is fixedly sleeved on the rotating shaft rod part between the rear ball bearing and the front ball bearing, the rotating shaft rod part between the magnetic ring and the front ball bearing is sleeved with an elastic part, one end of the elastic part enables the front ball bearing to be abutted in the first cavity, and the other end of the elastic part is abutted against the magnetic ring so that the rear ball bearing is abutted in the mounting cover. The utility model has the advantages of compact structure space, stability, reliability, easy installation, porous heat dissipation, prolonged service life, smooth fluid path and the like.

Description

Improved brushless motor

Technical Field

The present invention relates to the field of motors, and more particularly, to an improved brushless motor.

Background

In the prior art, the problems of a small motor or a micro motor are as follows: the high-speed brushless motor in the prior art has the following defects:

1. the impeller of the existing motor structure is easy to axially loosen in high-speed operation.

2. The existing motor structure is easy to generate noise under high rotating speed operation.

3. The existing motor has small volume, but has large power, namely, the current density is large, the temperature rise of the motor is high, and the motor efficiency is low.

SUMMERY OF THE UTILITY MODEL

To solve the above problems, the present invention provides an improved brushless motor.

In order to achieve the purpose, the utility model adopts the following technical scheme: an improved brushless motor comprises a frame, a stator assembly, a rotor assembly and an installation cover, wherein an installation cavity is arranged in the middle of the frame, the installation cover is installed on a spigot of the installation cavity, a first cavity and a second cavity which are communicated with each other are sequentially arranged in the installation cavity from an air inlet to an air outlet, the stator assembly is arranged in the second cavity, the rotor assembly is arranged in the stator assembly, the rotor assembly comprises a rotating shaft, and two ends of the rotating shaft respectively penetrate through a rear ball bearing and a front ball bearing; a magnetic ring is sleeved on the rotating shaft rod part between the rear ball bearing and the front ball bearing, an elastic part is sleeved on the rotating shaft rod part between the magnetic ring and the front ball bearing, one end of the elastic part enables the front ball bearing to be abutted in the first cavity, and the other end of the elastic part is abutted against the magnetic ring so that the rear ball bearing is abutted in the mounting cover.

Preferably, the second cavity is provided with an end face at the joint with the first cavity, and a plurality of vent holes are uniformly distributed on the end face along the periphery of the end face.

Preferably, the mounting cover is sequentially provided with a bearing accommodating cavity and a rotating shaft extending hole from outside to inside, a second stop step surface is arranged between the bearing accommodating cavity and the rotating shaft extending hole, and a plurality of holes which are symmetrically and uniformly distributed at intervals are formed between the outer edge of the mounting cover and the center of the rotating shaft extending hole along the axial direction.

Preferably, the diameter of the first cavity is smaller than that of the second cavity, and a diagonal plane for guiding flow is arranged between the outer wall surface and the end surface of the second cavity.

Preferably, the impeller is installed to the first end of pivot, the impeller middle part is equipped with the pivot jack, the first end of pivot is equipped with the screw thread blind hole, pivot jack and screw thread blind hole spiro union are worn to establish by spacing screw, the pivot jack is equipped with the spacing groove, two parallel planes of nut and spacing groove cooperation of spacing screw.

Preferably, at least one tangent plane is arranged on the outer wall surface of the frame.

Preferably, the inner wall surface of the second cavity is sequentially provided with a first annular step and a second annular step from the air inlet to the air outlet, the first cavity is provided with a seam allowance step at one end far away from the end surface, and the second step and the second cavity are enclosed to form a seam allowance.

Preferably, the frame includes an outer casing of a tubular body and an inner casing coaxial with the outer casing, the outer casing may extend beyond the inner casing in an upstream direction along an axial direction, the outer casing may extend beyond the inner casing or be flush with the inner casing in a downstream direction along the axial direction, an axial length of the second cavity is longer than an axial length of the guide vane, the chamfer is provided in an upstream direction of the guide vane, and the second cavity may extend beyond the guide vane in a downstream direction along the axial direction.

Preferably, the impeller includes a hub having a hub outer diameter less than the second cavity outer diameter, the circuit board outer diameter less than the mounting cup outer diameter, and the mounting cup outer diameter less than or equal to the second cavity outer diameter.

Preferably, the circuit board further comprises a circuit board, wherein the outer edge of the circuit board is provided with at least one straight edge, and the circuit board is in a regular hexagon shape with round corners.

The utility model has the beneficial effects that: the utility model has the advantages of compact structure space, stability, reliability, easy installation, porous heat dissipation, prolonged service life, smooth fluid path and the like.

1. The impeller and the rotating shaft are in threaded connection through the rotating shaft inserting hole and the threaded blind hole through the limiting screw, and two parallel surfaces of the nut of the limiting screw are matched with the limiting groove, so that the impeller is prevented from axially loosening in high-speed operation and from slipping in the circumferential direction relative to the shaft.

2. The frame is provided with an air duct structure and an installation cover is arranged in a spigot of the installation cavity, the front ball bearing and the rear ball bearing are respectively sleeved and fixed on the rotating shaft, the outer ring of the front ball bearing is fixed in the installation cavity, the outer ring of the rear ball bearing is fixed in the installation cover, and the installation cover, the installation cavity, the front ball bearing and the rear ball bearing are positioned on the same axis, so that the rotating shafts of the front ball bearing and the rear ball bearing are uniformly stressed and do not generate noise, and then the elastic piece provides pre-pressure from the inside of the shaft to the outside of the shaft to enable the inner ring of the front ball bearing to be abutted against the first cavity and enable the rear ball bearing to be abutted against the bearing hole of the installation cover, thereby eliminating the axial clearance of the front ball bearing and the rear ball bearing, further achieving the purpose of reducing the running noise of the bearing, further enabling the motor not to generate abnormal sound when being started and achieving the purpose of mute starting,

3. the end surface of the bottom of the second mounting cavity for supporting the rotor assembly and the stator assembly is provided with the plurality of vent holes, so that hot air in the mounting cavity is discharged, and the service life of the motor can be prolonged.

Drawings

FIG. 1 is a perspective view of the downstream side of the present invention.

Fig. 2 is an exploded view of the present invention.

Fig. 3 is a cross-sectional view of the present invention.

Fig. 4 is an enlarged view of fig. 3 at B.

FIG. 5 is a perspective view of the upstream side of the frame of the present invention.

Fig. 6 is a cross-sectional view of a downstream side of the frame of the present invention.

FIG. 7 is a top view of the upstream side of the housing of the present invention.

Fig. 8 is a perspective view of a rotor assembly according to the present invention.

Fig. 9 is a cross-sectional view of a rotor assembly of the present invention.

Fig. 10 is a perspective view of a stator assembly of the present invention.

Figure 11 is an exploded view of the stator assembly component assembly of the present invention.

FIG. 12 is a schematic perspective view of the downstream side of the mounting cup of the present invention.

FIG. 13 is a schematic view of the upstream side of the mounting cup of the present invention.

FIG. 14 is a schematic view of an impeller and a rotating shaft assembly according to the present invention.

Fig. 15 is a schematic diagram of the circuit board structure of the present invention.

Fig. 16 is a cross-sectional view of the housing of the present invention.

1. A frame; 11. an outer housing; 111. fixing a limiting hole; 12. a mounting cavity; 121. a first cavity; 1211. a first step; 1212. a second step; 1213. a chamfer plane; 122. a second cavity; 1221. a spigot step; 123. an end face; 13. a vent hole; 14. cutting into noodles; 15. an inner housing; 2. an annular channel; 23. a guide vane; 3. a stator assembly; 31. an insulating framework; 32. a stator core; 33. a conductive winding structure; 331. stator teeth; 332. a stator slot; 333. winding; 34. a rotor assembly cavity; 4. a rotor assembly; 41. a rotating shaft; 411. a threaded blind hole; 42. a magnetic ring; 43. a front ball bearing; 44. a rear ball bearing; 45. an impeller; 451. a hub; 4511. a boss; 452. a fan blade; 453. a rotating shaft jack; 454. a limiting groove; 46. a limiting screw; 47. a shaft sleeve; 5. mounting a cover; 51. a bearing accommodating cavity; 52. a cavity; 53. inserting a pin; 54. glue columns; 55. the rotating shaft extends out of the hole; 56. a second stop step surface; 57. an insulating tube; 6. a circuit board; 61. straight sides; 7. a spring.

Detailed Description

For clarity, the term "axial" means an axial direction extending along the rotational axis of the motor, such as axis a-a shown in fig. 2. Furthermore, the directional terms "upstream" and "downstream" herein refer to the direction of fluid flow through the motor when in use, and are also indicated by the double arrows in fig. 2.

Referring to fig. 1 to 16, the present invention relates to an improved brushless motor, including a frame 1, a stator assembly 3, a rotor assembly 4, and an installation cover 5, where the frame 1 includes an outer casing 11 in a tubular shape and an inner casing 15 coaxial with the outer casing 11, a front-rear through annular passage 2 is provided between the inner casing 15 and the outer casing 11, the front and rear of the outer casing 11 are respectively provided with an air inlet and an air outlet communicated with the annular passage 2, a plurality of guide vanes 23 are provided between an inner wall surface of the outer casing 11 and an outer wall surface of the inner casing 15, the outer casing 11 and the inner casing 15 are connected into a whole through the guide vanes 23, the guide vanes 23 are uniformly spirally distributed in the annular passage 2, and a cavity formed between the guide vanes 23 forms an air duct structure. Inner housing 15 has a front and back through installation cavity 12, stator module 3 is arranged in installation cavity 12, rotor assembly 4 is arranged in stator module 3, and installation cover 5 is installed on stator module 3 and abuts against second step 1212 of installation cavity 12.

Preferably, the frame 1 is made of zinc or zinc alloy and may be formed by, for example, machining or compression molding, or a combination of both machining and compression molding. Zinc is an acoustically dull material so that the housing 1 is able to effectively absorb the acoustic frequencies generated by the motor during use. The housing 1 thus serves to reduce the noise level generated by the product in which the motor is incorporated.

Preferably, the outer wall surface of the outer shell 11 is provided with at least one tangent plane 14, and in this embodiment, four tangent planes 14 are uniformly distributed on the outer surface of the outer shell 11 along the circumference, so that the outer surface of the rack 1 is a discontinuous cylindrical surface. The section 14 defines the rolling of the frame 1 and is convenient for playing a role of limiting in the manufacturing process of the motor combination product.

Preferably, the installation cavity 12 is sequentially provided with a first cavity 121 and a second cavity 122 which are communicated with each other in the direction from the air inlet to the air outlet, the diameter of the first cavity 121 is smaller than that of the second cavity 122, the second cavity 122 is provided with an end surface 123 at the joint with the first cavity 121, and a plurality of vent holes 13 are uniformly distributed on the end surface 123 along the periphery of the end surface.

In the prior art (CN212367013U), in order to exhaust the air inside the mounting cavity 12, a groove is generally formed on the surface along the axial length of the inner housing 15, and the hot air generated by the rotation of the rotor needs to bypass the stator assembly in the mounting cavity 12 to exhaust the air from the mounting cavity 12.

Preferably, the inner wall surface of the second cavity 122 is provided with a first annular step 1211 and a second annular step 1212 in sequence from the air inlet to the air outlet, the first cavity 121 is provided with a spigot step 1221 at an end away from the end surface 123, when the motor is assembled, the first cavity 121 can support the front ball bearing 43 in the mounting cavity 12, and the second cavity 122 can support the stator assembly 3 and the rotor assembly 4 in the mounting cavity 12. The spring 7 is pre-pressed on the inner ring of the front ball bearing 43, so that the outer ring of the front ball bearing 43 abuts against the spigot step 1221, since the stator assembly 3 is a circular ring type step cylinder, the first step 1211 enables the stator assembly 3 to be easily installed in the second cavity 122 and to be in interference fit with the second cavity 122, and the circular second step 1212 forms a spigot for installing the cover 5.

Preferably, a chamfer 1213 for guiding the flow is provided between the outer wall surface of the second cavity 122 and the end surface 123.

Preferably, the outer wall of the outer casing 11 may further be provided with a fixing and limiting hole 111 to facilitate limiting of a subsequent motor combined product, such as an electric hair dryer, an electric toothbrush, and the like.

Preferably, as shown in fig. 16, the axial length d of the outer housing 11 is longer than the axial length (b + c) of the mounting cavity 12, the axial length b of the second cavity 122 is longer than the axial length a of the guide vane 23, and the axial length a of the guide vane 23 is longer than the axial length c of the first cavity 121.

Preferably, the stator assembly 3 includes an insulating framework 31 and a stator core 32, and a rotor assembly cavity 34 is arranged in the stator core 32; the rotor assembly 4 is arranged in the rotor assembly accommodating cavity 34, the insulating framework 31 is wrapped on the outer wall of the stator tooth 331 of the stator core 32, the conductive winding structure 33 is arranged around the interior of the stator core 32, and the conductive winding structure 33 comprises the stator tooth 331, a stator slot 332 and a winding set 333.

Preferably, the rotor assembly 4 includes a rotating shaft 41, a magnetic ring 42, a front ball bearing 43, a rear ball bearing 44 and an impeller 45, wherein two ends of the rotating shaft 41 are respectively fixed to the rear ball bearing 44 and the front ball bearing 43; the magnetic ring 42 is fixedly sleeved on the shaft 41 between the rear ball bearing 44 and the front ball bearing 43, the magnetic ring 42, the front ball bearing 43 and the rear ball bearing 44 are directly fixed on the shaft 41 through one or a combination of interference fit and adhesive, the magnetic ring 42 is made of a permanent magnetic ring, the magnetic ring 42 can be rotated after being electrified by the conductive winding structure 33 on the stator assembly 3, and the shaft between the magnetic ring 42 and the front ball bearing 43 is sleeved with an elastic piece. One end of the elastic element abuts against the inner ring of the front ball bearing 43, and the other end abuts against the magnetic ring 42.

Preferably, the rotor assembly 4 is supported in the frame 1 by the second cavity 122, the front ball bearing 43 is mounted in the first cavity 121, the rear ball bearing 44 is mounted in the bearing receiving cavity 51 of the mounting cap 5, the first cavity 121 acts as a protective sleeve around the front ball bearing 43, and the mounting cap 5 acts as a protective sleeve around the rear ball bearing 44. This eliminates the need for separate protective casings for the front and

rear ball bearings

43, 44 and helps to reduce the size and weight of the motor. The outer race of the front ball bearing 43 is fixed to the inner periphery of the inner wall of the first cavity 121.

Preferably, the elastic member is a pre-pressed spring 7 or a rubber pad.

Preferably, a first washer and a second washer are respectively disposed at two ends of the spring, the first washer pre-presses an inner ring of the front ball bearing, and the second washer pre-presses one end of the magnetic ring 42.

Preferably, the impeller 45 is connected to the rotating shaft 41, the impeller 45 is installed at the first end of the rotating shaft 41 in the axial direction, the material of the impeller 45 is an aluminum alloy, aluminum is a very light material, and thus the weight of the motor is reduced by forming the impeller 45 using it. The impeller 45 includes a hub 451 and a number of fan blades 452 spaced circumferentially about the hub 451 and extending radially outward from the hub 451. The plurality of fan blades 452 are arranged in a ventilation area (air inlet) of the air duct structure. It is therefore possible to design the impeller 45 in such a way as to reduce its acoustic impact. The number of fan blades may vary depending on the acoustic requirements of the motor and/or the product to which the motor is to be incorporated. The first end of pivot 41 is equipped with screw thread blind hole 411, the middle part of hub 451 is equipped with boss 4511, boss 4511 middle part is equipped with spacing groove 454, the both sides face of spacing groove 454 link up to the boss 4511 top surface, pivot jack 453 has been seted up to spacing groove 454 bottom surface, stop screw 46 wears to establish pivot jack 453 and screw thread blind hole 411 spiro union, two parallel planes of nut and the cooperation of the both sides face of spacing groove 454 of stop screw 46, ensure that impeller 45 does not take place axial pine and impeller 45 is relative axial in the high-speed operation and also the slippage is not gone up to the circumferencial direction.

Preferably, as shown in fig. 16, the axial length of the outer housing 11 is d, the axial length of the second cavity 122 is b, the axial length of the first cavity 121 is c, the axial length of the guide vane 23 is a, the axial length d of the outer housing 11 is longer than the axial length (b + c) of the inner housing 15, the outer housing 11 may extend beyond the inner housing 15 in the upstream direction along the axial direction, available space is arranged on the inner wall of the outer shell 11 in the upstream direction, the fan blades can be placed in the hidden type fan blades, the outer shell 11 can extend beyond the inner shell 15 in the downstream direction along the axial direction or is flush with the inner shell 15, space is saved, the axial length b of the second cavity 122 is longer than the axial length a of the guide vane 23, the chamfer 1213 is arranged in the upstream direction of the guide vane 23, the second cavity can extend beyond the guide vane 23 in the downstream direction along the axial direction, and the air volume effect is better.

Preferably, the outer diameter of the hub 451 is smaller than the outer diameter of the second cavity 122, the outer diameter of the circuit board 6 is smaller than the outer diameter of the mounting cover 5, and the outer diameter of the mounting cover 5 is smaller than or equal to the outer diameter of the second cavity 122, so that the air inlet formed at the upstream of the frame 1 is larger and the air outlet formed at the downstream is larger, thereby forming a path for facilitating the smooth flow of fluid.

Preferably, the mounting cover 5 is made of metal alloy or plastic, the mounting cover 5 is provided with a bearing receiving cavity 51 and a rotating shaft extending hole 55, a second stop step surface 56 is arranged between the bearing receiving cavity 51 and the rotating shaft extending hole 55, the second stop step surface 56 is used for limiting the outer ring of the rear ball bearing 44, the diameter of the bearing receiving cavity 51 is larger than that of the rotating shaft extending hole 55, the diameter of the rotating shaft extending hole 55 is larger than that of the inner ring of the rear ball bearing 44, the mounting cover 5 is symmetrically and uniformly distributed with a plurality of holes 52 around the center of the rotating shaft extending hole 55, the bearing receiving cavity 51 is used for mounting the rear ball bearing 44, the outer ring of the rear ball bearing 44 is fixed to the inner periphery of the inner wall of the bearing receiving cavity 51, the outer ring abuts against the second stop step surface 56, the rotating shaft of the rotor assembly penetrates out of the holes 52 from the rotating shaft extending hole 55 for the insertion pin 53 to pass through, a copper wire (a wire end of a winding group, not marked in the figure) wires need to be wound on the outer edges of six rubber columns 54 of the insulating framework 31, the wire heads and the wire tails are firstly respectively welded on six contact pins 53, one ends of the six contact pins need to penetrate through six holes 52 of the installation cover 5 and are welded with the external circuit board 6, the other ends of the six contact pins are inserted into the rubber columns 54, the contact pins 53 welded with copper wires are partially sleeved in the insulating pipes 57, or the copper wires and the contact pins are wrapped together by using an adhesive tape, so that the creepage distance and the insulation voltage resistance between the contact pins 53 and the installation cover 5 are ensured to be qualified, the holes 52 can lighten the weight of the installation cover, the stress balance of the motor can be kept, the ventilation and the heat dissipation can be realized, the service life of the motor can be prolonged, and the safe power utilization distance between the electric wiring harnesses can be ensured.

Preferably, the circuit board 6 has at least one straight edge 61 on its outer edge, preferably a regular polygon with rounded corners. And under the condition of the same diameter, the area of the polygonal circuit board 6 is relatively smaller, and the air quantity blocked by the circuit board 6 at the air outlet can be reduced, for example, compared with the polygonal circuit board 6, the area of the polygonal circuit board 6 is smaller than that of the circular circuit board with the same diameter, so that the area of the circuit board is reduced, the wind resistance and the noise are reduced, the air pressure of the motor is improved, and the generation of blowing abnormal sound is avoided.

Preferably, the axial lines of the bearing accommodating cavity 51, the rotating shaft protruding hole 55, the front ball bearing 43 and the rear ball bearing 44 are coaxial with the axial line of the mounting cavity 12. Therefore, the rotating shafts of the front ball bearing 43 and the rear ball bearing 44 are uniformly stressed, and relatively less noise is generated.

In the technical scheme, the pre-pressing spring 7 applies a first acting force F to the inner ring of the front ball bearing 43¹During the process, the pre-pressing spring 7 exerts a second acting force F on the magnetic ring 42²So that the pre-pressing spring 7 indirectly generates a third acting force F in the same direction to the inner ring of the rear ball bearing 44 through the magnetic ring 42³(ii) a The spigot step 1221 of the first cavity 121 applies a fourth force F to the outer race of the front ball bearing 43⁴The second stop step surface 56 of the mounting cover 5 applies a fifth acting force F to the outer race of the rear ball bearing 44^5，So that the front ball bearing 43 is stopped from moving in the first cavity 121 and the rear ball bearing 44 is stopped from moving in the mounting cup 5. The rotating shaft 41 cannot move back and forth, so that the axial clearance between the front ball bearing 43 and the rear ball bearing 44 is eliminated, the purpose of reducing the running noise of the bearings is achieved, and the noise reduction effect of the front ball bearing 43 and the rear ball bearing 44 is better when the bearings run at high speed.

In the prior art (CN212969295U), acting force from outside to inside is applied to the front bearing and the rear bearing respectively through the front limiting ring and the rear limiting ring, wherein a certain limiting ring is an impeller 45, the impeller 45 applies external force to the front ball bearing, the rear limiting ring applies external force to the rear ball bearing, the structure in the scheme is obvious compared with the prior art, the front ball bearing is limited by a spigot step in a rack and a bearing accommodating cavity integrally formed with an installation cover respectively, the elastic part prepressing front ball bearing is limited through the installation cavity, meanwhile, the elastic part prepressing magnetic ring 42 and a shaft sleeve 47 also perform prepressing on the rear ball bearing, the installation cover is limited on the rear ball bearing, so as to eliminate the axial clearance of the front ball bearing 43 and the rear ball bearing 44, and a gasket and a clearance are arranged between the impeller and the front ball bearing in the scheme. The pre-pressing spring 7 applies force to the outside of the shaft from the middle of the shaft, and the pre-pressing force is resisted on the machine frame 1, in the motor structure of the utility model, the impeller 45 does not contact with the front ball bearing to apply the pre-pressing force, and the damage to the impeller 45 is avoided.

The above embodiments are merely illustrative of the preferred embodiments of the present invention, and not restrictive, and various changes and modifications to the technical solutions of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are intended to fall within the scope of the present invention defined by the appended claims.

Claims

1. An improved brushless motor, comprising a frame, a stator assembly, a rotor assembly and a mounting cover, characterized in that: the middle part of the rack is provided with an installation cavity, the installation cover is installed on a spigot of the installation cavity, the installation cavity is sequentially provided with a first cavity and a second cavity which are communicated with each other from an air inlet to an air outlet, the stator assembly is arranged in the second cavity, the rotor assembly is arranged in the stator assembly, the rotor assembly comprises a rotating shaft, and two ends of the rotating shaft are fixedly penetrated in the rear ball bearing and the front ball bearing respectively; a magnetic ring is sleeved on the rotating shaft rod part between the rear ball bearing and the front ball bearing, an elastic part is sleeved on the rotating shaft rod part between the magnetic ring and the front ball bearing, one end of the elastic part enables the front ball bearing to be abutted in the first cavity, and the other end of the elastic part is abutted against the magnetic ring so that the rear ball bearing is abutted in the mounting cover.

2. An improved brushless motor as recited in claim 1, wherein: the second cavity is equipped with the terminal surface with first cavity handing-over department, and its periphery equipartition has a plurality of ventilation hole on the terminal surface.

3. An improved brushless motor as recited in claim 1, wherein: the mounting cover is provided with a bearing accommodating cavity and a rotating shaft extending hole, a second stop step surface is arranged between the bearing accommodating cavity and the rotating shaft extending hole, and a plurality of holes which are symmetrically distributed at equal intervals are formed between the outer edge of the mounting cover and the center of the rotating shaft extending hole along the axial direction.

4. An improved brushless motor as recited in claim 1, wherein: the diameter of the first cavity is smaller than that of the second cavity, and a chamfer plane for guiding flow is arranged between the outer wall surface and the end surface of the second cavity.

5. An improved brushless motor as recited in claim 1, wherein: the impeller is installed to the first end of pivot, the impeller middle part is equipped with the pivot jack, the first end of pivot is equipped with the screw thread blind hole, and pivot jack and screw thread blind hole spiro union are worn to establish by spacing screw, the pivot jack is equipped with the spacing groove, two parallel planes of nut and spacing groove cooperation of spacing screw.

6. An improved brushless motor as recited in claim 1, wherein: at least one tangent plane is arranged on the outer wall surface of the frame.

7. An improved brushless motor as recited in claim 1, wherein: the inner wall surface of the second cavity is sequentially provided with a first annular step and a second annular step from the air inlet to the air outlet, the end, far away from the end face, of the first cavity is provided with a spigot step, and the second step and the second cavity are enclosed to form a spigot.

8. An improved brushless motor as recited in claim 4, wherein: the frame is including the shell body that is the siphonozooid and the interior casing with the same axial lead of shell body, the shell body can be followed axial direction and extended beyond interior casing in upstream direction, the shell body can be followed axial direction and extended beyond interior casing or with interior casing parallel and level in downstream direction, the axial length of second cavity is longer than guide vane's axial length, the scarf is established on guide vane upstream direction, the second cavity can be followed axial direction and extended beyond guide vane in downstream direction.

9. An improved brushless motor as recited in claim 5, wherein: the impeller comprises a hub, the outer diameter of the hub is smaller than the outer diameter of the second cavity, and the outer diameter of the mounting cover is smaller than or equal to the outer diameter of the second cavity.

10. An improved brushless motor as recited in claim 1, wherein: the circuit board is characterized by further comprising a circuit board, wherein at least one straight edge is arranged on the outer edge of the circuit board, and the outer diameter of the circuit board is smaller than that of the mounting cover.