PCB stator and motor

Abstract

The invention provides a PCB stator and a motor. The PCB stator comprises a first printed circuit board main body, a stator winding and a driving control circuit. The stator winding includes a coil group disposed on the first printed circuit board body, and a current density of coils in the coil group is disposed in a range of 2 A / mm2 to 35 A / mm2. The driving control circuit is arranged on the first printed circuit board main body and can control the stator winding. The motor comprises the above PCB stator. The integrated design, production and integration of the drive control circuit and the stator winding are realized, and the production and assembly difficulty of the stator is greatly simplified. Besides, the current density of the coil of the stator winding is configured in a range of 2A / mm < 2 > to 35A / mm < 2 >, so that the heating and the power can be balanced, and the working efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of axial flux motors, and in particular to a PCB stator in which a drive control circuit and a stator winding are integrated on a PCB (printed circuit board) and a motor having the PCB stator. Background Art

[0002] Integrated motors with integrated drive control circuits have wide demand and application prospects in aerospace, new energy vehicles and other fields. Currently, integrated motors basically adopt the form of installing motor drive controllers at the tail or outside of the traditional motor body to achieve a structural integration of a shared housing. The degree of integration between the drive control circuit and the motor needs to be improved.

[0003] For example, US2015 / 0084446A1 discloses a direct-drive stacked motor actuator. The motor actuator includes a plurality of rotors and stators arranged alternately. Each stator has a plurality of coils embedded in a printed circuit board (PCB) as wiring. The control board of the motor actuator is a separate circuit board, which is arranged on one axial side of all stators and rotors.

[0004] Compared with traditional radial flux motors, axial flux motors have the advantages of high power density and high torque density. However, the manufacturing complexity of axial flux motor stator components limits its large-scale production and application. Summary of the invention

[0005] In order to solve or improve at least one of the problems mentioned in the background technology, the present application provides a PCB stator and a motor.

[0006] The PCB stator provided in the embodiment of the present application includes:

[0007] a first printed circuit board body;

[0008] The stator winding comprises a coil group arranged on the first printed circuit board body, and the current density of the coils in the coil group is configured at 2A / mm 2 Up to 35A / mm 2 within the scope;

[0009] A drive control circuit is provided on the first printed circuit board body and is capable of controlling the stator winding.

[0010] In at least one embodiment, multiple layers of the coil group are arranged in parallel on the first printed circuit board body, and the total current flowing through the coil group on the first printed circuit board body / [the line width of the wire in the coil group×the thickness of one layer of the coil×the number of layers of the coil group]=2A / mm 2 Up to 35A / mm 2.

[0011] In at least one embodiment, multiple layers of the coil group connected in series or only one layer of the coil group is arranged on the first printed circuit board body, and the total current flowing through the coil group on the first printed circuit board body / [the line width of the wire in the coil group×the thickness of one layer of the coil]=2A / mm 2 Up to 35A / mm 2 .

[0012] In at least one embodiment, the PCB stator includes a first printed circuit board body and at least one second printed circuit board body, the stator winding also includes a coil group arranged on the second printed circuit board body, the first printed circuit board body and the second printed circuit board body are arranged side by side in the thickness direction, and the second printed circuit board body is electrically connected to the drive control circuit of the first printed circuit board body.

[0013] The motor provided in the embodiment of the present application includes the PCB stator as described above.

[0014] In at least one embodiment, a plurality of the first printed circuit board bodies are arranged side by side in the axial direction of the motor.

[0015] In at least one embodiment, the motor further includes a heat dissipation cold plate, the heat dissipation cold plate abuts against the PCB stator, and a cooling channel and a corresponding channel inlet and channel outlet are provided in the heat dissipation cold plate.

[0016] In at least one embodiment, the electric machine further comprises a rotor, the rotor comprising:

[0017] A rotating shaft, the rotating shaft comprising a first rotating shaft portion, the first rotating shaft portion being provided with a positioning step;

[0018] a pair of iron cores, the iron cores are arranged in pairs on the first portion of the rotating shaft, and the iron cores abut against the positioning step;

[0019] A permanent magnet is arranged on the axial inner side of the iron core, and the PCB stator is arranged on the axial inner side of the permanent magnet.

[0020] In at least one embodiment, the motor further comprises a pair of motor housings, wherein the motor housings are arranged on both sides of the PCB stator in a thickness direction, and a stepped hole is arranged at the center of the motor housing.

[0021] The rotating shaft comprises a second rotating shaft portion and a third rotating shaft portion located at two axial ends of the first rotating shaft portion. The second rotating shaft portion and the third rotating shaft portion are respectively provided with bearings, and the bearings abut against the stepped hole and the first rotating shaft portion in the axial direction.

[0022] In at least one embodiment, heat dissipation reinforcement ribs protruding axially outward are provided on the axial surface of the motor housing.

[0023] This application realizes the integrated design, production and integration of the drive control circuit and the stator winding, greatly simplifying the difficulty of stator production and assembly. In addition, the current density of the coil of the stator winding is configured at 2A / mm 2 Up to 35A / mm 2 Within the specified range, it can balance heat generation and power and improve work efficiency.

[0024] The motor provided in the present application has the above-mentioned PCB stator and also has the above-mentioned advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A front view of a first printed circuit board body of a PCB stator according to an embodiment of the present application is shown.

[0026] Figure 2 A side view of a first printed circuit board body of a PCB stator according to an embodiment of the present application is shown.

[0027] Figure 3 A perspective view of a first printed circuit board body of a PCB stator according to an embodiment of the present application is shown.

[0028] Figure 4 A front view of a second printed circuit board body of a PCB stator according to an embodiment of the present application is shown.

[0029] Figure 5 Shows Figure 4 AA cross-sectional view of the second printed circuit board body of the PCB stator.

[0030] Figure 6 An isometric view of a second printed circuit board body of a PCB stator according to an embodiment of the present application is shown.

[0031] Figure 7 A front view of a heat dissipation cold plate of a motor according to an embodiment of the present application is shown.

[0032] Figure 8 A top view of a heat dissipation cold plate of a motor according to an embodiment of the present application is shown.

[0033] Fig. 9 Shows Figure 8 BB cross-sectional view of the heat dissipation cold plate of the motor.

[0034] Fig.10 An axonometric view of a heat dissipation cold plate of a motor according to an embodiment of the present application is shown.

[0035] Fig.11 A front view of a rotor of a motor according to an embodiment of the present application is shown.

[0036] Fig.12 Shows Fig.11 CC cross-sectional view of the rotor of the motor.

[0037] Fig.13 An axonometric view of a rotor of an electric machine according to an embodiment of the present application is shown.

[0038] Fig.14 A front view of a motor housing and a first printed circuit board body of a PCB stator of a motor according to an embodiment of the present application is shown.

[0039] Fig.15 Shows Fig.14 DD cross-sectional view of the motor housing and the first printed circuit board body of the PCB stator of the motor.

[0040] Fig.16 An isometric view of a motor housing and a first printed circuit board body of a PCB stator of a motor according to an embodiment of the present application is shown.

[0041] Fig.17 A front view of a motor according to a first embodiment of the present application is shown.

[0042] Fig.18 Shows Fig.17 EE cross-sectional view of the motor in FIG.

[0043] Fig.19 An axonometric view of a motor according to a first embodiment of the present application is shown.

[0044] Fig. 20 A front view of a motor according to a second embodiment of the present application is shown.

[0045] Fig.21 Shows Fig. 20 FF cross-sectional view of the motor in.

[0046] Fig. 22 An axonometric view of a motor according to a second embodiment of the present application is shown.

[0047] Description of Reference Numerals

[0048] 100 a first printed circuit board body;

[0049] 200 stator winding; 210 coil group;

[0050] 300 driving control circuit;

[0051] 400 a second printed circuit board body;

[0052] 500 heat dissipation cold plate; 510 cooling channel; 520 channel inlet; 530 channel outlet;

[0053] 600 rotor; 610 rotating shaft; 611 first rotating shaft portion; 612 second rotating shaft portion; 613 third rotating shaft portion; 620 iron core; 630 permanent magnet; 640 bearing; 650 positioning step; 660 axial screw hole;

[0054] 700 motor housing; 710 stepped hole; 720 heat dissipation reinforcement rib; 730 wire hole; 740 wire; 750 seal; 760 sealing ring DETAILED DESCRIPTION

[0055] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0056] The embodiments of the present application provide a PCB stator and a motor.

[0057] See also Figure 1 , Figure 2 and Figure 3 The PCB stator may include a first printed circuit board body 100, a stator winding 200 and a drive control circuit 300. The stator winding 200 may include a coil group 210 disposed on the first printed circuit board body 100, and the drive control circuit 300 is integrated in the first printed circuit board body 100 and can control the stator winding 200.

[0058] The coil group 210 of the stator winding 200 and the drive control circuit 300 can be processed together through the PCB manufacturing process, which can realize the integrated design, production and integration of the drive control circuit 300 and the stator winding 200, greatly simplifying the difficulty of stator production and assembly.

[0059] In one embodiment of the present application, see Figure 1 , Figure 2 and Figure 3 , there is no iron core in the stator winding 200. Removing the stator iron core of the traditional motor can remove the iron loss, thereby improving the power density and efficiency of the motor using the PCB stator. Of course, the stator winding 200 can also be provided with an iron core.

[0060] In one embodiment of the present application, see Fig.18 and Fig.21 The PCB stator may include a plurality of first printed circuit board bodies 100 arranged side by side in the thickness direction. By increasing or decreasing the number of the first printed circuit board bodies, the power can be changed conveniently without redesigning the production.

[0061] In one embodiment of the present application, see Figure 4 , Figure 5 and Figure 6 The PCB stator may include a second printed circuit board body 400, on which the coil group 210 is arranged, and no drive control circuit 300 is arranged. The PCB stator may include a first printed circuit board body 100 and at least one second printed circuit board body 400, the first printed circuit board body 100 and the second printed circuit board body 400 are arranged side by side in the thickness direction, and the second printed circuit board body 400 is electrically connected to the drive control circuit 300 located in the first printed circuit board body 100.

[0062] In one embodiment of the present application, see Figure 1 , Figure 2 and Figure 3 The coil in the stator winding 200 can be a circle, a rhombus, a parallelogram or other shapes with a closed loop between the inner and outer coils. Of course, the coil can also be formed in the form of a spiral line. The present application does not limit the specific shape of the coil.

[0063] The radius of the circumscribed circle and the radius of the inscribed circle of the coil group 210 in the stator winding 200 are related to the area of ​​the coil and the permanent magnetic flux of the turns, and indirectly determine the back electromotive force of the winding. For example, see Figure 1 and Fig.12 , the circumscribed circle radius R1 and the inscribed circle radius R2 of the coil group 210 can satisfy: the circumscribed circle radius R1 of the coil group 210 = (1.1-1.2) × the circumscribed circle radius R3 of the permanent magnet 630 (described later) of the rotor 600, and the inscribed circle radius R2 of the coil group 210 = (0.8-0.9) × the inscribed circle radius R4 of the permanent magnet 630 of the rotor 600. That is, the orthographic projection of the coil can cover the orthographic projection of the permanent magnet 630.

[0064] The coils of the stator winding 200 can be evenly distributed in the circumferential direction, and the number of coils can be determined by the pole slot matching selection of the motor, and the present application does not limit the specific number. For example, the first printed circuit board body 100 can be provided with 12 groups of coils, each group of coils includes 5 concentric coils.

[0065] In one embodiment of the present application, in order to balance the heat generation and working efficiency, the current density in the coils of the coil assembly 210 can be configured to be 2A / mm 2 Up to 35A / mm 2 The determination of the current density of the coils in the stator winding 200 needs to take into account the loss and the limitation of the PCB stator temperature.

[0066] As for the loss, it can include the loss of the stator winding 200 and the loss of the drive circuit 300. The stator winding 200 will have resistance after winding, and will generate loss after current is passed. At the same time, the components in the drive control circuit 300 will also generate loss, and since the drive control circuit 300 and the stator winding 200 are on the same PCB, the heat generated by the drive control circuit 300 will also affect the temperature rise of the stator winding 200, so the loss generated by the drive control circuit 300 should also be considered.

[0067] Regarding the stator temperature limit, the stator temperature limit of an ordinary motor is the maximum temperature limit of the winding, for example, 240° C. However, the PCB stator provided in this application includes a stator winding 200 and a drive control circuit 300, and the temperature limit of the PCB stator is the components in the drive control circuit 300, for example, 175° C.

[0068] A high-precision thermal resistance network model can be established for the PCB stator. For example, in terms of winding loss, the cross-sectional area and resistance of the coil in the stator winding 200 can be taken into consideration. In terms of the loss of the drive control circuit 300, the loss caused by the on-resistance of the device in the drive control circuit 300 (the current size can be determined according to the product of the current density in the stator winding 200 and the cross-sectional area of ​​the coil, and then the loss of the on-resistance of the device in the drive control circuit 300 can be determined according to the current) and the switching loss can be taken into consideration. In addition, the heat dissipation thermal resistance of the heat dissipation cold plate 500 (if any, to be introduced later), the heat transfer thermal resistance and the heat dissipation thermal resistance of the PCB stator can also be taken into consideration to solve the current density corresponding to the temperature rise limit of the PCB stator. The inventors of the present application found that when the current density reaches 35A / mm 2 When the maximum temperature of the components in the drive control circuit 300 reaches 150°C, which is close to its upper temperature limit, but still within the acceptable range. In order to ensure a certain safety margin, the application limits the maximum value of the current density to 35A / mm 2 .

[0069] In one embodiment of the present application, a multi-layer coil group 210 connected in parallel is arranged on the first printed circuit board body 100, and the total current flowing through the coil group 210 on the first printed circuit board body 100 / (the line width of the wire in the coil group 210×the thickness of one layer of coil×the number of layers of the coil group 210)=2-35A / mm 2 .

[0070] In one embodiment of the present application, a plurality of layers of coil groups 210 connected in series or only one layer of coil group 210 is provided in the thickness direction of the first printed circuit board body 100, and the total current flowing through the coil group 210 on the first printed circuit board body 100 / (the line width of the wire in the coil group 210×the thickness of one layer of coil)=2-35A / mm 2 .

[0071] For example, the thickness of one layer of coil is generally 0.07-0.35 mm. The number of layers of the coil group 210 can be selected according to the actual current size and current density, and is generally designed with 2-10 layers. The total current flowing through the coil group 210 on the first printed circuit board body 100 can be the current that supplies power to the coil group 210 on the first printed circuit board body 100.

[0072] In one embodiment of the present application, see Figure 1 The drive control circuit 300 can be arranged on the axial outside of the stator winding 200 and can be located outside the positive projection of the outer circular contour of the rotor 600 to reduce the electromagnetic interference of the magnetic field on the components related to the drive control circuit. Exemplarily, the components of the drive control circuit 300 can include MOS tubes (metal oxide semiconductor field effect tubes), capacitors, and connection terminals.

[0073] In one embodiment of the present application, the substrate of the printed circuit board (the first printed circuit board body 100, the second printed circuit board body 400) can be made of flame-retardant, non-conductive materials, such as FR4 (Flame Retardant Type 4) material, which includes epoxy resin and glass fiber cloth to avoid eddy current loss in the printed circuit board.

[0074] The motor provided in the embodiment of the present application may include the aforementioned PCB stator. The motor may be applicable to motors in the fields of hub motors, propellers, ducted fans, blowers, industrial pumps, servo drives, etc. Of course, the motor may also be a generator.

[0075] In one embodiment of the present application, see Figure 7 , Figure 8 , Fig. 9 and Fig.10 The motor includes a heat dissipation cold plate 500, which can strengthen the cooling and heat dissipation of the PCB stator. The heat dissipation cold plate 500 is provided with a cooling channel 510 and a corresponding channel inlet 520 and a channel outlet 530, and water cooling and heat dissipation are achieved by passing cooling water. Exemplarily, the cross section of the cooling channel 510 can be formed into a ring shape to cover the position of the stator winding 200 to the maximum extent, and the channel inlet 520 and the channel outlet 530 can be located at the same end of the heat dissipation cold plate 500.

[0076] See also Fig.18 and Fig.21, the heat dissipation cold plate 500 can be against the PCB stator. For example, the heat dissipation cold plate 500 and the first printed circuit board body 100 are alternately arranged to form a layout of "first printed circuit board body 100-heat dissipation cold plate 500-first printed circuit board body 100" or "first printed circuit board body 100-heat dissipation cold plate 500-first printed circuit board body 100-heat dissipation cold plate 500-first printed circuit board body 100".

[0077] Exemplarily, the thickness of the heat dissipation cold plate 500 can be, for example, 0.5 to 0.8 times the thickness of a single first printed circuit board body 100. Its thin thickness facilitates reducing the size of the motor, reducing the air gap, and improving the heat transfer effect. The heat dissipation cold plate 500 can be manufactured using processes such as 3D printing or powder die-casting, and its material can be a highly thermally conductive non-conductive material, such as nylon, ceramic, PEEK (polyetheretherketone), etc., which is suitable for workspaces with large alternating magnetic fields.

[0078] In one embodiment of the present application, see Fig.11 , Fig.12 and Fig.13 The motor may include a rotor 600, and the rotor 600 may include a rotating shaft 610, an iron core 620, and a permanent magnet 630. The rotating shaft 610 may include a rotating shaft first portion 611, a rotating shaft second portion 612, and a rotating shaft third portion 613.

[0079] The first part 611 of the rotating shaft can be used as an axis to support the iron core 620 and the PCB stator, the second part 612 of the rotating shaft can be used as an output shaft, and the third part 613 of the rotating shaft can be used as an axis to support the bearing 640 (described later).

[0080] A positioning step 650 may be provided on the first portion 611 of the rotating shaft. The iron cores 620 may be provided in pairs on the first portion 611 of the rotating shaft, and the iron cores 620 abut against the positioning step 650 to control the axial spacing between the permanent magnets 630 on the two iron cores 620. An axial screw hole 660 may be provided on the first portion 611 of the rotating shaft, and the iron cores 620 may be threadedly fixed on the axial screw hole 660. The permanent magnet 630 may be an axially magnetized magnetic steel, and is provided on the axial inner side of the iron core 620. The PCB stator may be provided on the axial inner side of the permanent magnet 630.

[0081] In one embodiment of the present application, see Fig.14 , Fig.15 , Fig.16 , Fig.18 and Fig.21The motor may include a pair of motor housings 700, which are arranged on both sides of the PCB stator in the thickness direction, and a stepped hole 710 is arranged at the center of the motor housing 700. Bearings 640 are respectively arranged on the second part 612 and the third part 613 of the rotating shaft of the rotor 600. The bearing 640 may be a radial bearing, and the bearing 640 also abuts against the axial end surface of the stepped hole 710 and the axial end surface of the first part 611 of the rotating shaft in the axial direction to achieve axial positioning of each component.

[0082] Through holes may be provided at, for example, four corners of the motor housing 700 and the PCB stator, and the motor housing 700 and the PCB stator may be fixed together by fasteners such as bolts. Meanwhile, the rotor 600 is also fixed due to the pressure between the bearing 640 and the stepped hole 710 .

[0083] It can be understood that the motor housing 700 can provide mechanical structural support and heat dissipation for the PCB motor stator. The motor housing 700 can be made of high thermal conductivity metal materials, such as aluminum alloy, aluminum-magnesium alloy, etc., and can be made by CNC (numerical control) processing, die casting, powder die casting and other processes. A number of heat dissipation reinforcement ribs 720 protruding axially outward can be set on the axial surface of the motor housing 700 to enhance the heat dissipation capacity and mechanical strength of the housing surface.

[0084] Further, see Fig.21 , Fig. 22 The motor housing 700 may be provided with a wire hole 730, through which the wire 740 may be connected to, for example, a PCB stator in the motor housing 700. The gap between the wire 740 and the wire hole 730 may be sealed by a seal 750 (for example, rubber).

[0085] Further, see Fig.21 and Fig. 22 A sealing ring 760 may be provided between the two motor housings 700 to prevent dust and other substances from entering the motor housings 700, thereby increasing the protective effect.

[0086] Below, this application provides two embodiments.

[0087] Embodiment 1

[0088] See also Fig.17 , Fig.18 and Fig.19 , the motor may include two first printed circuit board bodies 100 and a rotor 600 .

[0089] Embodiment 2

[0090] See also Fig. 20 , Fig.21 and Fig. 22The motor may include three first printed circuit board bodies 100 and a rotor 600 , and the axial length of the rotor 600 is correspondingly increased compared with the first embodiment.

[0091] Of course, more first printed circuit board bodies 100 and rotors 600 of corresponding sizes may be provided to meet corresponding requirements.

[0092] Some advantages of the PCB stator and motor provided by this application are as follows.

[0093] (1) The stator winding 200 and the drive control circuit 300 are designed as an integrated whole and manufactured using PCB circuit board technology, which has the advantages of strong processability, easy production and detection;

[0094] (2) The stator winding 200 and the drive control circuit 300 adopt an integrated PCB design, which can greatly reduce the difficulty of assembling the stator winding 200 and the drive control circuit 300. No external tooling is required, and only the required electronic components need to be soldered to the PCB;

[0095] (3) Compared with traditional motor stators, the integrated PCB stator has no iron core, which further eliminates core loss and torque fluctuation, and improves motor efficiency, power density and running stability;

[0096] (4) The PCB stator gives the motor flexible power scalability. By increasing or decreasing the number of PCB stators in the axial direction, the power can be increased or decreased without redesigning and producing a new stator.

[0097] (5) The heat dissipation cold plate 500 provides a heat dissipation channel for the stator assembly, which is beneficial to the heat dissipation of the stator.

[0098] It is understood that the aforementioned ranges in this application all include their endpoint values. For example, the range A to B includes the two endpoint values ​​A and B.

[0099] The above is a preferred embodiment of the present application. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A PCB stator, characterized in that: include: A first printed circuit board body (100); A stator winding (200), the stator winding (200) comprising a coil group (210) arranged on the first printed circuit board body (100), the current density of the coils in the coil group (210) being configured at 2A / mm 2 Up to 35A / mm 2 within the scope; A drive control circuit (300) is provided on the first printed circuit board body (100) and is capable of controlling the stator winding (200).

2. The PCB stator according to claim 1, characterized in that: The first printed circuit board body (100) is provided with multiple layers of the coil group (210) connected in parallel, and the total current flowing through the coil group (210) on the first printed circuit board body (100) / [the line width of the conductor in the coil group (210)×the thickness of one layer of the coil×the number of layers of the coil group (210)]=2A / mm 2 Up to 35A / mm 2 .

3. The PCB stator according to claim 1, characterized in that: The first printed circuit board body (100) is provided with multiple layers of the coil group (210) connected in series or only one layer of the coil group (210), and the total current flowing through the coil group (210) on the first printed circuit board body (100) / [the line width of the conductor in the coil group (210)×the thickness of one layer of the coil]=2A / mm 2 Up to 35A / mm 2 .

4. The PCB stator according to claim 1, characterized in that: The PCB stator comprises a first printed circuit board body (100) and at least one second printed circuit board body (400); the stator winding (200) further comprises a coil group (210) arranged on the second printed circuit board body (400); the first printed circuit board body (100) and the second printed circuit board body (400) are arranged side by side in a thickness direction; and the second printed circuit board body (400) is electrically connected to the drive control circuit (300) of the first printed circuit board body (100).

5. A motor, characterized in that: A PCB stator comprising any one of claims 1 to 4.

6. The motor according to claim 5, characterized in that It comprises a plurality of first printed circuit board bodies (100) arranged side by side in the axial direction of the motor.

7. The motor according to claim 5, characterized in that The motor further comprises a heat dissipation cold plate (500), the heat dissipation cold plate (500) being against the PCB stator, and a cooling channel (510) and corresponding channel inlets (520) and channel outlets (530) being arranged in the heat dissipation cold plate (500).

8. The motor according to claim 5, characterized in that The motor further comprises a rotor (600), wherein the rotor (600) comprises: A rotating shaft (610), the rotating shaft (610) comprising a first rotating shaft portion (611), and a positioning step (650) is provided on the first rotating shaft portion (611); a pair of iron cores (620), the iron cores (620) being arranged in pairs on the first portion (611) of the rotating shaft, and the iron cores (620) being against the positioning step (650); A permanent magnet (630), wherein the permanent magnet (630) is arranged axially inside the iron core (620), and the PCB stator is arranged axially inside the permanent magnet (630).

9. The motor according to claim 8, characterized in that The motor further comprises a pair of motor housings (700), wherein the motor housings (700) are arranged on both sides of the PCB stator in a thickness direction, and a stepped hole (710) is arranged at the center of the motor housing (700). The rotating shaft (610) comprises a second rotating shaft portion (612) and a third rotating shaft portion (613) located at two axial ends of the first rotating shaft portion (611); bearings (640) are respectively provided on the second rotating shaft portion (612) and the third rotating shaft portion (613); and the bearings (640) abut against the stepped hole (710) and the first rotating shaft portion (611) in the axial direction.

10. The motor according to claim 9, characterized in that The motor housing (700) is provided with heat dissipation reinforcement ribs (720) protruding axially outward on the axial surface.

Images