Brushless motor and manufacturing method of brushless motor

Abstract

The application relates to the field of electric machines, and discloses a brushless motor, which comprises a stator and a rotor rotatably arranged in the stator, the stator comprises a stator core, an insulating frame sleeved on the stator core, and a winding arranged on the insulating frame, the stator core comprises an annular yoke part and a tooth pole part installed on the radially inner side of the yoke part, the tooth pole part comprises a plurality of tooth parts distributed in a circumferential direction at intervals and an annular pole part arranged on and connected with the radially inner side of the plurality of tooth parts, the radially outer side of the plurality of tooth parts abuts against the radially inner side of the yoke part, the insulating frame is arranged on the tooth pole part, a plurality of power supply terminals are fixed to the axial one end of the insulating frame, and the plurality of power supply terminals are electrically connected with the winding respectively. The brushless motor stator of the application has high winding efficiency and simple assembly process. The application further discloses a manufacturing method of the brushless motor.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular to a brushless motor and a method for manufacturing the brushless motor. Background Art

[0002] The stator of the brushless motor includes a stator core, an insulating frame covering the surface of the stator core, and a stator winding wound on the insulating frame. The stator core includes an annular yoke and a plurality of pole teeth extending inward from the yoke.

[0003] Common stator cores include integrated and segmented structures. An integrated stator core is composed of several axially stacked laminations, each with an integrally connected yoke and pole teeth. A segmented stator core is composed of several circumferentially assembled segments, each of which is composed of several axially stacked segmented laminations. Each lamination includes a pole tooth and its corresponding portion of the yoke.

[0004] For an integrated stator core structure, when winding the winding, since the openings between adjacent pole teeth of the stator core face radially inward and the spacing between adjacent pole teeth is very small, a needle winding machine is required to wind the corresponding pole teeth, and the winding efficiency is very low.

[0005] Although the segmented stator core structure's circumferential segments are independent and can be wound simultaneously, improving winding efficiency, the segments still need to be assembled together after winding, making the assembly process complex. Furthermore, the stator corresponding to this segmented stator core structure is generally large, making it particularly unsuitable for stators with an outer diameter of less than 50 mm. In particular, after assembling the segments, the support brackets for mounting the terminals (for connecting the windings and the controller) must be attached to the insulating frame, further complicating the stator assembly process and increasing manufacturing costs. Summary of the Invention

[0006] In view of this, the present invention aims to provide a brushless motor and a method for manufacturing a brushless motor that can solve the above problems or at least solve the above problems to a certain extent.

[0007] To this end, the present invention provides a brushless motor, comprising a stator and a rotor rotatably arranged in the stator, the stator comprising a stator core, an insulating frame sleeved on the stator core, and a winding wound on the insulating frame, the stator core comprising an annular yoke portion and a tooth pole portion mounted on the radial inner side of the yoke portion, the tooth pole portion comprising a plurality of teeth spaced apart along the circumferential direction, and an annular pole portion arranged radially inner than the plurality of teeth and connected to the radial inner sides of the plurality of teeth, the radial outer sides of the plurality of teeth abutting the radial inner side of the yoke, the insulating frame being located on the tooth pole portion, a plurality of power terminals being fixed to one axial end of the insulating frame, the plurality of power terminals being electrically connected to the winding respectively.

[0008] In some embodiments, the stator further includes an axial length compensation ring provided on the axial end surface of the yoke by overmolding or installation.

[0009] In some embodiments, the insulating frame is arranged on the tooth pole portion by overmolding or installation, and the insulating frame includes an inner ring corresponding to the annular pole portion, and several branches corresponding one-to-one to the several teeth, and the winding is wound on the surface of the branches.

[0010] In some embodiments, the annular pole portion includes a plurality of pole shoes corresponding one-to-one to the plurality of teeth, and adjacent pole shoes are connected by means of a bridging portion.

[0011] In some embodiments, the radially outer ends of the teeth protrude beyond the radially outer ends of the branches.

[0012] In some embodiments, the insulating frame further includes a connecting frame formed at an axial end of the inner ring, and a bearing seat is formed in the center of the connecting frame.

[0013] In some embodiments, the insulating frame further includes at least two opposing protrusions formed on the radial inner side of the inner ring, and the protrusions protrude radially inward.

[0014] In some embodiments, a grounding terminal is further fixed to one axial end of the insulating frame, and the grounding terminal includes a first end extending in the axial direction and a second end extending radially outward.

[0015] In some embodiments, the brushless motor further includes a metal shell and a controller, and the brushless motor stator further includes a grounding terminal, one end of the grounding terminal is connected to the controller, and the other end is connected to the metal shell, and the controller is grounded through the grounding terminal.

[0016] In another aspect, the present invention further provides a method for manufacturing a brushless motor, comprising the following steps:

[0017] 1) providing a tooth pole portion, the tooth pole portion comprising a plurality of teeth spaced apart along the circumferential direction, and an annular pole portion arranged radially inwardly of the plurality of teeth and connected to the radially inwardly of the plurality of teeth;

[0018] 2) forming or installing an insulating frame on the tooth pole portion, the insulating frame comprising an inner ring corresponding to the annular pole portion and a plurality of branches corresponding one-to-one to the plurality of teeth; a plurality of power terminals are fixed to one axial end of the inner ring;

[0019] 3) Winding a winding on each branch of the insulating frame and connecting the winding to the corresponding power terminal;

[0020] 4) providing a yoke, and press-fitting the tooth pole portion into the yoke, with the radial outer sides of the plurality of teeth abutting against the radial inner side of the yoke;

[0021] 5) Provide a rotor.

[0022] In some embodiments, a connecting frame is integrally formed at one axial end of the inner ring, and the connecting frame is injection-molded onto the multiple power terminals or the multiple power terminals are mounted on the connecting frame.

[0023] In some embodiments, at least two oppositely arranged protrusions are formed on the radial inner side of the inner ring for abutting against the radial outer wall of a rotor.

[0024] In some embodiments, an axial length compensation ring is provided on the axial end surface of the yoke by injection molding or installation.

[0025] In some embodiments, in step 2), a ground terminal is further fixed to the axial end of the inner ring.

[0026] The present invention provides a stator core comprising an annular yoke and teeth mounted radially inwardly of the yoke. This allows winding to be first wound on an insulating frame above the teeth, and then the wound teeth are assembled into the yoke, thereby improving winding efficiency. Furthermore, the yoke and teeth can be stamped simultaneously, and after winding is complete, only the teeth need to be assembled into the yoke, simplifying the assembly process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. 1 is a perspective view of a brushless motor according to an embodiment of the present invention.

[0028] Figure 2 yes Figure 1 Exploded view of the brushless motor shown.

[0029] Figure 3 yes Figure 1 Longitudinal cross-section of the brushless motor shown.

[0030] Figure 4 yes Figure 1 A transverse cross-sectional view of the brushless motor shown.

[0031] Figure 5 yes Figure 1 Schematic diagram of the assembly of the stator and rotor of the brushless motor shown.

[0032] Figure 6 yes Figure 5 Longitudinal section view of the stator and rotor shown.

[0033] Figure 7 yes Figure 5 Exploded view of the stator and rotor shown.

[0034] Figure 8 yes Figure 5 Exploded view of the stator shown. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments to make the technical solutions and beneficial effects of the present invention more clearly understood. It should be understood that the drawings are provided for reference and illustration only and are not intended to limit the present invention. The dimensions shown in the drawings are only for the purpose of clarification and do not limit the proportional relationship.

[0036] refer to Figures 1 to 4 A brushless motor according to an embodiment of the present invention includes a metal housing 10, a stator 20 housed in the metal housing 10, and a rotor 30 rotatably housed in the stator 20. A receiving cavity 21 is formed in the center of the stator 20, and the stator 20 has an open end 22. The rotor 30 is adapted to be assembled into the receiving cavity 21 through the open end 22.

[0037] In this embodiment, the metal shell 10 is in the shape of a hollow cylinder with both ends open, and its inner wall extends radially inward to form an annular flange 11. The lower end face of the stator 20 is supported on the upper end face of the annular flange 11. The brushless motor also includes an end cover 40 abutting the lower end face of the annular flange 11, and a mounting seat 50 supported on the upper end face of the stator 20. One end of the rotating shaft 31 of the rotor 30 protrudes from the lower end face of the stator 20 and is rotatably connected to the end cover 40, and the other end of the rotating shaft 31 protrudes from the upper end face of the stator 20 and is rotatably connected to the mounting seat 50. The mounting seat 50 is provided with a receiving groove 51 for mounting a connecting portion 53 electrically connected to the controller 52.

[0038] Preferably, the outer diameter of the brushless motor is less than or equal to 50 mm. In this embodiment, the brushless motor is a six-slot four-pole motor. Specifically, the stator 20 includes six tooth pole portions and six tooth slots formed by the six tooth pole portions, and the rotor 30 includes four magnetic steels 32. In other embodiments, the brushless motor may also include other numbers of tooth slots and magnetic poles, such as a six-slot two-pole. In this embodiment, the stator windings 60 are connected in a Y-shape. The stator 20 includes multiple power terminals, including first, second, and third terminals 61, 62, and 63, which are electrically connected to one end of each of the three groups of windings 60, and a common terminal 64, which is electrically connected to the other ends of the three groups of windings 60. In other embodiments, the stator windings 60 may also be connected in a delta shape, in which case the common terminal 64 is no longer required. Preferably, the stator 20 also includes a grounding terminal 65, which abuts the radial inner wall of the metal housing 10 to achieve grounding. One end of each of the first, second, third, and fourth terminals 61 , 62 , 63 , 64 and the ground terminal 65 passes through the mounting base 50 and is electrically connected to a connection portion 53 mounted in the mounting base 50 .

[0039] refer to Figures 4 to 7 In this embodiment, the stator 20 includes a stator core 70, an insulating frame 80 sleeved on the stator core 70, and the winding 60 wound on the insulating frame 80. The stator core 70 includes an annular yoke 71 and a tooth pole portion 72 mounted on the radial inner wall of the yoke 71. Both the yoke 71 and the tooth pole portion 72 can be formed by stacking a plurality of stamped laminations. The tooth pole portion 72 includes a plurality of teeth 73 spaced apart along the circumference, and an annular pole portion 74 arranged radially inwardly of the plurality of teeth 73 and connected to the plurality of teeth 73. The radial outer walls of the plurality of teeth 73 abut the radial inner wall of the yoke 71. The annular pole portion 74 includes a plurality of pole shoes 740 corresponding to the plurality of teeth 73. Adjacent pole shoes 740 are connected by a bridge portion 741. In this way, the integrity of the plurality of teeth 73 can be improved, making assembly easier. In this embodiment, three bridge portions 741 distributed along the axial direction are included between adjacent pole shoes 740, and a spacing groove 742 is formed between adjacent bridge portions 741. The insulating frame 80 is sleeved on the surface of the tooth pole portion 72. In this way, when winding the winding 60, the winding 60 can be first wound on the insulating frame 80 on the tooth pole portion 72 corresponding to the tooth portion 73, and then the wound tooth pole portion 72 can be assembled into the yoke portion 71, thereby improving the winding efficiency. In addition, the yoke portion 71 and the tooth pole portion 72 in this embodiment can be stamped and manufactured at the same time, and after the winding is completed, only the tooth pole portion 72 needs to be assembled to the yoke portion 71, thereby simplifying the assembly process.

[0040] Preferably, the stator 20 also includes an axial length compensation ring 91 provided on an axial end face of the yoke 71 by injection molding or installation, for compensating for the axial installation tolerance between the yoke 71 and the metal shell 10, so that the yoke 71 remains in the correct installation position. In this embodiment, the stator 20 includes two axial length compensation rings 91 formed on the two axial end faces of the yoke 71 by injection molding, and a plurality of connecting strips 92 connecting the two axial length compensation rings 91 on the radial inner side of the two axial length compensation rings 91. The plurality of connecting strips 92 are evenly spaced along the circumferential direction. The yoke 71 is arranged between the two axial length compensation rings 91. One of the axial length compensation rings 91 is suitable for supporting the annular flange 11 of the metal shell 10, and the other axial length compensation ring 91 is suitable for supporting the mounting seat 50 ( Figure 3 To improve the connection strength between the yoke 71 and the axial length compensation ring 91, protrusions 910 may be formed on the end surfaces of the two axial length compensation rings 91 facing the yoke 71, and correspondingly, grooves 710 may be formed on the end surfaces of the yoke 71 facing the axial length compensation ring 91. The cooperation between the protrusions 910 and the grooves 710 makes the connection between the yoke 71 and the axial length compensation ring 91 more stable.

[0041] The insulating frame 80 can be attached to the surface of the tooth pole portion 72 by overmolding or mounting. In this embodiment, the insulating frame 80 includes an inner ring 81 corresponding to the pole portion 74 and a plurality of branches 82 corresponding one-to-one to the plurality of teeth 73. The winding 60 is wound on the surface of the branches 82. In this embodiment, a protrusion 810 is formed on the radial inner wall of the inner ring 81 corresponding to the spacing groove 742, and the protrusion 810 is received in the spacing groove 742. Preferably, the inner ring 81 covers the radial outer wall and both axial end surfaces of the pole portion 74. The branches 82 cover the circumferential side walls and both axial end surfaces of the tooth portion 73. More preferably, each branch 82 further includes a stopper 820 formed radially outwardly of each circumferential side wall to limit the winding 60 on the branch 82. The stopper 820 extends circumferentially from the corresponding side wall in a direction away from the tooth portion 73. In this embodiment, all the stoppers 820 of the insulating frame 80 are located on the same cylindrical surface. The radial outer side of the tooth portion 73 preferably protrudes from the radial outer side of the branch 82, that is, the outer diameter of the tooth portion 73 is preferably larger than the outer diameter of the stopper 820 ( Figure 4 As shown in the partial enlarged view in FIG. , when the tooth portion 72 is press-fitted until its tooth portion 73 abuts the inner wall of the yoke portion 71 , a certain gap is formed between the insulating frame 80 and the yoke portion 71 , without interfering with the assembly of the tooth portion 72 , and the insulating frame 80 is not deformed due to being squeezed.

[0042] More preferably, one end face of the branch 82 in the axial direction further extends radially outward to form a first limiting portion 821 for abutting against the end face of the yoke 71 or the end face of the axial length compensation ring 91. Preferably, the first limiting portion 821 is arranged at the open end 22 of the stator 20. Due to the design of the first limiting portion 821, when the tooth pole portion 72 (which has been overmolded or installed with the insulating frame 80 and the winding is completed) is assembled to the yoke 71, the first limiting portion 821 on the insulating frame 80 abuts against the end face of the yoke 71 or the end face of the axial length compensation ring 91 (such as Figure 5 As shown), the tooth pole portion 72 in the insulating frame 80 is axially positioned, so that the tooth pole portion 72 is installed in the correct position. Preferably, the first limiting portion 821 protrudes axially from one end portion 600 of the winding 60 to further limit the radial outer side of the end portion 600 of the winding 60 at the same time. The inner ring 81 of the insulating frame 80 can also extend axially at the open end 22 to form a plurality of second limiting portions 811 to further limit the radial inner side of one end portion 600 of the winding 60. In this embodiment, the plurality of second limiting portions 811 are evenly spaced along the circumferential direction, and each branch 82 corresponds to a second limiting portion 811. More preferably, at least two oppositely arranged protrusions 812 are further formed on the radial inner side of the inner ring 81. Before assembling the metal shell 10, the rotor 30 can be assembled into the receiving cavity 21 of the stator 20 through the open end 22, and the radial outer wall of the rotor 30 is in contact with the protrusion 812 ( Figure 5 and Figure 6 (as can be seen) to overcome the magnetic force acting on the rotor 30, thereby maintaining the rotor 30 in the correct position and facilitating installation of the rotor 30. In this embodiment, the inner ring 81 includes three protrusions 812 evenly spaced around the circumference. Each protrusion 812 is formed on the radial inner wall of a second stopper 811.

[0043] refer to Figure 8Preferably, the inner ring 81 further extends axially at the end away from the open end 22 to the other end 601 protruding from the winding 60 to further limit the winding 60. Preferably, the end of the inner ring 81 is a regular polygon, and in this embodiment, it is a regular hexagon. In this embodiment, a connecting frame 83 is further formed at the end of the inner ring 81. The connecting frame 83 is injection molded on the terminals 61-65, or the terminals 61-65 are installed on the connecting frame 83. The periphery of the connecting frame 83 is integrally connected to the end of the inner ring 81, so the connecting frame 83 in this embodiment is also a regular hexagon. The connecting frame 83 is integrally formed with the insulating frame 80, so there is no need to additionally assemble a bracket for mounting the terminal to the insulating frame 80, which not only further simplifies the assembly process of the stator 20, but also saves manufacturing costs. A bearing seat 830 is formed in the center of the connecting frame 83 . A bearing is installed in or integrally formed in the bearing seat 830 for supporting the rotating shaft 31 of the rotor 30 .

[0044] In this embodiment, the first, second, and third terminals 61-63 and the grounding terminal 65 are arranged corresponding to one side length of the connecting frame 83, respectively, and the common terminal 64 is arranged corresponding to the other two adjacent sides of the connecting frame 83. Specifically, the end surface of the connecting frame 83 is axially recessed to form slots 831, 832, and 833 corresponding to the first, second, and third terminals 61-63, respectively, and two adjacent slots 834 corresponding to the common terminal 64. The terminals 61-64 are respectively inserted into the corresponding slots. Unlike the first, second, third, and common terminals 61, 62, 63, and 64, in this embodiment, the grounding terminal 65 is used to achieve grounding of the controller 52, and includes a first end 651 extending axially for connecting to the controller 52, and a second end 652 extending radially outward for abutting the radial inner wall of the metal shell 10. Due to the forceful interaction between the second end 652 of the grounding terminal 65 and the radially inner wall of the metal housing 10, the connecting frame 83 also includes a support boss 836 for supporting the grounding terminal 65, thereby enhancing the mechanical strength of the connecting frame 83 at this location. A slot 835 is formed within the support boss 836 to accommodate the grounding terminal 65. To enhance the connection stability between each terminal and its corresponding slot, at least one barb 660 is formed on the sidewall of each pin facing the slot, with the tip of the barb 660 pointing in the direction of removal of the terminal from the slot, effectively preventing the terminal from falling out of the slot.

[0045] The manufacturing method of the brushless motor in the embodiment of the present invention will be further described below.

[0046] Step 1: Provide and assemble the stator 20; A: Provide the tooth pole portion 72, the tooth pole portion 72 including a plurality of teeth 73 spaced apart along the circumferential direction, and a plurality of teeth 73 arranged radially inwardly of the plurality of teeth 73 and radially opposite to the plurality of teeth 73;

[0047] an annular pole portion 74 connected inwardly;

[0048] B. The insulating frame 80 is provided on the tooth pole portion 72. The insulating frame 80 includes an inner ring 81 corresponding to the annular pole portion 74 and a plurality of branches 82 corresponding one-to-one to the plurality of teeth 73. The first, second, and third terminals and the common terminals 61, 62, 63, and 64 are fixed to one axial end of the inner ring 81 of the insulating frame 80.

[0049] The insulating frame 80 can be overmolded or mounted on the tooth pole portion 72. The insulating frame 80 can be directly injection molded onto the multiple terminals 61-64, or formed with multiple slots for mounting the multiple terminals 61-64. Preferably, at least two oppositely arranged protrusions 812 are formed on the radially inner side of the inner ring 81. The protrusions 812 are configured to abut against the radial outer wall of the rotor 30 to overcome the magnetic force acting on the rotor 30 and pre-position the rotor 30.

[0050] C. Winding a winding 60 on each branch 82 of the insulating frame 80 and connecting the winding 60 to the corresponding terminal;

[0051] D. providing the yoke 71;

[0052] Preferably, the axial length compensation ring 91 is first formed on the end surface of the yoke 71 by injection molding.

[0053] E. Press-fit the tooth pole portion 72 together with the insulating frame 80 and the terminals into the yoke portion 71 , so that the radial outer walls of the plurality of tooth portions 73 abut against the radial inner wall of the yoke portion 71 .

[0054] Preferably, when the first stop 821 abuts the axial length compensation ring 91, the tooth portion 72 stops moving. At this point, the grounding terminal 65 can be plugged into the insulating frame 80, completing the assembly of the stator 20. It should be understood that the insulating frame 80 can also be injection-molded onto the grounding terminal 65 to simplify the assembly process.

[0055] Step 2: Assemble the rotor 30 into the stator 20;

[0056] A rotor 30 is provided and assembled into the receiving cavity 21 of the stator 20 through the open end 22 of the stator 20. Preferably, when the rotor 30 is assembled into the stator 20, the protrusion 812 of the insulating frame 80 of the stator 20 abuts against the radial outer wall of the rotor 30.

[0057] Step 3: Assemble the stator 20 and the rotor 30 to the metal housing 10 .

[0058] A metal shell 10 is provided, and the metal shell 10 is sleeved onto the outer peripheral wall of the stator 20 , and the second end 652 of the grounding terminal 65 abuts against the inner wall of the metal shell 10 to achieve grounding.

[0059] The above description is only a preferred specific embodiment of the present invention. The scope of protection of the present invention is not limited to the embodiments listed above. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with this technical field within the technical scope disclosed in the present invention fall within the scope of protection of the present invention.

Claims

1. A brushless motor comprising a stator and a rotor rotatably disposed in the stator, wherein the stator comprises a stator core, an insulating frame sleeved on the stator core, and a winding wound on the insulating frame, wherein: The stator core includes an annular yoke portion and a tooth pole portion mounted on the radial inner side of the yoke portion, the tooth pole portion including a plurality of teeth spaced apart along the circumferential direction and an annular pole portion arranged radially inwardly of the plurality of teeth and connected to the radial inner sides of the plurality of teeth, the radial outer sides of the plurality of teeth abutting the radial inner side of the yoke portion, the insulating frame being located on the tooth pole portion, a plurality of power terminals being fixed to one axial end of the insulating frame, the plurality of power terminals being electrically connected to the windings respectively; the insulating frame being disposed on the tooth pole portion by overmolding or mounting, and including an inner ring corresponding to the annular pole portion; The insulating frame also includes at least two opposing protrusions formed on the radial inner side of the inner ring, and the protrusions protrude radially inward to abut against the radial outer wall of the rotor during assembly of the rotor, so that the force exerted by the protrusions on the rotor can resist the electromagnetic force exerted on the rotor until the rotor is assembled into the stator.

2. The brushless motor according to claim 1, wherein: The stator further includes an axial length compensation ring which is arranged on the axial end surface of the yoke by overmolding or installation.

3. The brushless motor according to claim 1, wherein: The insulating frame further includes a plurality of branches corresponding to the plurality of teeth, and the winding is wound on surfaces of the branches.

4. The brushless motor according to claim 1, wherein: The annular pole portion includes a plurality of pole shoes corresponding to the plurality of teeth, and adjacent pole shoes are connected by means of a bridging portion.

5. The brushless motor according to claim 3, characterized in that: The radially outer ends of the teeth protrude beyond the radially outer ends of the branches.

6. The brushless motor according to claim 3, characterized in that The insulating frame further includes a connecting frame formed at an axial end of the inner ring, and a bearing seat is formed in the center of the connecting frame.

7. The brushless motor according to claim 1, wherein: A grounding terminal is further fixed to one axial end of the insulating frame. The grounding terminal includes a first end extending in the axial direction and a second end extending radially outward.

8. The brushless motor according to claim 1, wherein: It also includes a metal shell and a controller. The stator also includes a grounding terminal. One end of the grounding terminal is connected to the controller, and the other end is connected to the metal shell. The controller is grounded through the grounding terminal.

9. A method for manufacturing a brushless motor, characterized in that: The following steps are involved: Provide a stator, including: 1) providing a tooth pole portion, the tooth pole portion comprising a plurality of teeth spaced apart along the circumferential direction, and an annular pole portion arranged radially inwardly of the plurality of teeth and connected to the radially inwardly of the plurality of teeth; 2) forming or installing an insulating frame on the tooth pole portion, the insulating frame comprising an inner ring corresponding to the annular pole portion and a plurality of branches corresponding one-to-one to the plurality of teeth; a plurality of power terminals are fixed to one axial end of the inner ring; 3) Winding a winding on each branch of the insulating frame and connecting the winding to the corresponding power terminal; 4) providing a yoke, press-fitting the tooth pole portion into the yoke, with the radial outer sides of the plurality of teeth abutting against the radial inner side of the yoke; and providing a rotor; In which, at least two oppositely arranged protrusions are formed on the radial inner side of the inner ring, and the protrusions protrude radially inward to abut the radial outer wall of the rotor during the assembly of the rotor, so that the force exerted by the protrusions on the rotor can resist the electromagnetic force exerted on the rotor until the rotor is assembled into the stator.

10. The method for manufacturing a brushless motor according to claim 9, wherein: A connecting frame is integrally formed at one axial end of the inner ring. The connecting frame is injection-molded on the multiple power terminals or the multiple power terminals are installed on the connecting frame.

11. The method for manufacturing a brushless motor according to claim 9, wherein: An axial length compensation ring is provided on the axial end surface of the yoke by injection molding or installation.

12. The method for manufacturing a brushless motor according to claim 10, wherein: In step 2), a ground terminal is further fixed to the axial end of the inner ring.

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