A permanent magnet brushless motor

Abstract

The application discloses a permanent magnet type brushless motor, which comprises a stator assembly, a rotor assembly and a permanent magnet type brushless motor body, wherein the stator assembly comprises a stator core and a coil winding; the rotor assembly comprises a rotating shaft and a rotor core arranged on the rotating shaft; the rotor assembly is arranged in the stator assembly and the rotor assembly and the stator assembly are coaxial; the stator core has an annular yoke part and a plurality of tooth parts extending to the central axis based on the annular yoke part; the coil winding is arranged around the tooth parts; one end of the tooth part towards the central axis is a circular arc surface; the tooth part comprises a first tooth part close to the annular yoke part and a second tooth part close to the rotor assembly and having a circular arc surface; the rotor core is provided with a plurality of permanent magnets; and the magnetic force line convergence points of each magnetic pole of the permanent magnets are located in the second tooth part. The permanent magnet type brushless motor has high efficiency, less vibration, low noise and can realize high-efficiency and mute operation.

Description

Technical Field

[0001] This invention relates to the field of electric motor technology, and more specifically, to a permanent magnet brushless electric motor. Background Technology

[0002] Currently, in the field of electromechanical products both domestically and internationally that use electric motors for driving, induction motors and permanent magnet brushed motors, which have relatively poor performance, are still used, especially in the fields of water pumps and fans. However, the performance of the electric motor directly affects the noise level of water pumps and fans. Brushless motors, due to their advantages of low noise, long lifespan, and high efficiency, are gradually replacing induction motors and brushed motors. However, with the continuous improvement of people's living standards, the performance requirements for brushless motors are also increasing. The research and development progress of brushless motors that simultaneously possess quiet operation, miniaturization, high efficiency, and smooth operation is not ideal and remains a current difficult and hot research topic. Summary of the Invention

[0003] Based on this, the present invention aims to overcome at least one defect of the prior art and provide a permanent magnet brushless motor, which has high efficiency, low vibration, low noise, and can achieve high-efficiency and quiet operation.

[0004] The technical solution is as follows:

[0005] A permanent magnet brushless motor, comprising:

[0006] Stator assembly, which includes stator core and coil windings;

[0007] A rotor assembly includes a rotating shaft and a rotor core disposed on the rotating shaft, the rotor assembly being disposed within the stator assembly, and the rotor assembly and the stator assembly sharing a common central axis;

[0008] The stator core has an annular yoke and several teeth extending toward the central axis based on the annular yoke. The coil winding is arranged around the teeth. The end of the teeth facing the central axis is an arc surface. The teeth include a first tooth near the annular yoke and a second tooth near the rotor assembly that has an arc surface. The width of the portion of the second tooth near the rotor assembly is greater than the width of the first tooth.

[0009] The rotor core is provided with a number of permanent magnets arranged alternately with "N" and "S" poles, and the magnetic field lines of each pole of the permanent magnet converge at the point inside the second tooth.

[0010] In one embodiment, the permanent magnet has a bread-shaped cross-section. The bread-shaped structure includes a first arc, a first straight line sharing a center line with the first arc, two second arcs symmetrically arranged on both sides of the center line and connected to the ends of the first straight line, and two second straight lines symmetrically arranged on both sides of the center line and connected to the ends of the first arc. Both second straight lines are perpendicular to the first straight line, and the distance between the two second straight lines is greater than the length of the first straight line. The first arc protrudes in a direction away from the axis of rotation, and the second arcs protrude in a direction away from the center of the permanent magnet.

[0011] In one embodiment, the distance between the two second straight lines is D, the distance from the axis of the rotating shaft to the first arc is R, the number of pole pairs of the permanent magnet is P, and D, R, and P satisfy: D = n * 2π * R / 2P, 0.80 ≤ n ≤ 0.85.

[0012] In one embodiment, the distance from the axis of the rotating shaft to the first arc is R, the distance from the highest point of the first arc to the first straight line is T1, and the length of the second straight line is T2. T1 and T2 satisfy: T2 = m * T1, 0.25 ≤ m ≤ 0.30; T1 = k * R, 0.25 ≤ k ≤ 0.30.

[0013] In one embodiment, the length of the first arc is greater than the arc length corresponding to the cross-section of the arc surface.

[0014] In one embodiment, the rotor core further includes a rotor yoke, the cross-section of which is a circular ring structure with several notches, the notches being located near the outer edge of the circular ring structure, the notches matching the bread-shaped structure and the radius of the first arc of the bread-shaped structure being greater than the radius of the outer ring of the circular ring structure, the first arc and the circular ring sharing the same center.

[0015] In one embodiment, a first radial air gap is provided between the teeth and the rotor yoke, and a second radial air gap is provided between the teeth and the permanent magnet.

[0016] In one embodiment, the second tooth includes an arc surface, two first planes and two second planes symmetrically arranged along the center line of the arc surface, the first planes smoothly transitioning to the arc surface, the two ends of the second planes smoothly transitioning to the first planes and the first tooth, respectively, and the distance between the end of the second plane closer to the first plane and the arc surface is smaller than the distance between the end of the second plane closer to the first tooth and the arc surface.

[0017] In one embodiment, the stator core and / or rotor core are composed of multiple layers of electromagnetic steel plates.

[0018] In one embodiment, the coil winding is arranged around the first tooth.

[0019] The beneficial effects of this invention are as follows: By designing the rotor core of the rotor assembly and the teeth of the stator assembly, the magnetic lines of force of each pole of the permanent magnet of the rotor core converge in a specific area of ​​the teeth of the stator assembly, which makes the magnetic field strength distribution sinusoidal, with small torque fluctuation and small magnetic reluctance change, thereby making the motor quieter, significantly reducing noise and vibration, and increasing the efficiency of the motor. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of a rotor core in the prior art.

[0021] Figure 2 This is a diagram illustrating the magnetic field lines of a rotor core in the prior art.

[0022] Figure 3 This is a perspective view of the permanent magnet brushless motor of Example 1.

[0023] Figure 4 This is a cross-sectional view of the permanent magnet brushless motor in Example 1.

[0024] Figure 5 This is a perspective view of the stator assembly in Example 1.

[0025] Figure 6 This is a perspective view of the rotor core of Example 1.

[0026] Figure 7 This is a partial cross-sectional view of the permanent magnet brushless motor of Example 1.

[0027] Figure 8 This is a partial cross-sectional view of the permanent magnet brushless motor of Example 1.

[0028] Figure 9 This is a partial cross-sectional view of the permanent magnet brushless motor of Example 1.

[0029] Figure 10 This is a partial cross-sectional view of the permanent magnet brushless motor of Example 1.

[0030] Figure 11 This is a comparison diagram of the magnetic field waveforms of the existing technology and the brushless motor of Embodiment 1.

[0031] Figure 12 This is a comparison chart of the motor efficiency of the current technology and the brushless motor of Embodiment 1.

[0032] Explanation of reference numerals in the attached drawings: 100, stator assembly; 101, stator core; 102, tooth; 1021, first tooth; 1022, second tooth; 103, coil winding; 104, annular yoke; 200, rotor assembly; 201, shaft; 202, rotor core; 203, permanent magnet; 204, rotor yoke. Detailed Implementation

[0033] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate the following embodiments, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; it is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] Technical documents have disclosed that the magnetic field waveform and reluctance variation can be improved by changing the thickness of the permanent magnet poles in the magnetic field orientation and designing non-uniform air gaps. This increases the magnetic flux density in the air gap between the stator and rotor of the motor, thereby improving output, reducing torque ripple, and decreasing noise. Figure 1 However, in this type of brushless motor, the magnetic field lines of the permanent magnet poles are parallel to the straight line connecting the center of the rotor and the center of the circumference of the permanent magnet poles. The magnetic field lines are parallel, meaning they point towards infinity. Figure 2 As shown. The magnetic field strength distribution on the outer circumference of the rotor surface of this brushless motor is as follows. Figure 11 The flat-top waveform shown is very different from the sine wave. It has problems such as low efficiency, high noise and vibration, and cannot meet the customer's requirements for quiet and high efficiency.

[0035] The permanent magnet brushless motor described in this application can simultaneously achieve high efficiency and quiet operation. The specific solution of this application is as follows: Example 1

[0036] like Figures 3 to 7As shown, this embodiment discloses a permanent magnet brushless motor, including: a stator assembly 100, which includes a stator core 101 and a coil winding 103; a rotor assembly 200, which includes a shaft 201 and a rotor core 202 disposed on the shaft 201, the rotor assembly 200 being disposed within the stator assembly 100, and the rotor assembly 200 and the stator assembly 100 sharing a central axis; the stator core 101 having an annular yoke 104 and a plurality of teeth 102 extending toward the central axis based on the annular yoke 104, the coil winding 103 being arranged around the teeth 102, the teeth 103 being... 2. One end facing the central axis is an arc surface S1. The tooth 102 includes a first tooth 1021 near the annular yoke 104 and a second tooth 1022 near the rotor assembly 200 and having an arc surface S1. The width of the portion of the second tooth 1022 near the rotor assembly 200 is greater than the width of the first tooth 1021 (the width refers to the length in the radial direction perpendicular to the rotating shaft). The rotor core 202 is provided with a plurality of permanent magnets 203 arranged alternately with "N" poles and "S" poles. The magnetic field lines of each pole of the permanent magnet 203 converge at the point within the second tooth 1022.

[0037] When the brushless motor is energized, the coil winding 103 is energized, thereby enabling the stator assembly 100 to generate an electromagnetic field. Since the rotor assembly 200 contains a permanent magnet 203, the permanent magnet 203, under the influence of the electromagnetic field, can drive the rotor assembly 200 to rotate around the shaft 201. This technical solution features a special design for the permanent magnet 203 and its teeth. By converging the magnetic lines of force of each pole of the permanent magnet 203 within the second tooth, the magnetic focusing effect of the rotor assembly is significant, and the magnetic field strength distribution exhibits a sinusoidal waveform. Figure 11 As shown, the torque fluctuation is small, making the motor quieter and significantly reducing noise and vibration. The specific principle is that the output torque and torque fluctuation of the permanent magnet brushless motor are closely related to the magnetic field strength curve on the rotor surface. The sinusoidal magnetic field strength curve, because it lacks abrupt magnetic field jumps, contributes to the motor's output and smooth operation, significantly improving efficiency and reducing noise and vibration. This technical solution achieves a sinusoidal magnetic field strength curve by converging the magnetic field lines of each pole of the permanent magnet 203 to a single point located within the second tooth.

[0038] Furthermore, to ensure that the magnetic field lines of all poles of the permanent magnet 203 converge at a single point located within the second tooth, the permanent magnet 203 in this embodiment has a bread-shaped cross-section, as shown below. Figure 8As shown, the bread-shaped structure includes a first arc C1, a first straight line L1 sharing a center line L0 with the first arc, two second arcs C2 symmetrically arranged on both sides of the center line L0 and connected to the two ends of the first straight line L1, and two second straight lines L2 symmetrically arranged on both sides of the center line L0 and connected to the two ends of the first arc C1. The first arc C1 is located on a circumference concentric with the axis of the rotating shaft 201. C1, L2, C2, L1, C2, and L2 are connected in sequence to form a closed structure. The two second straight lines L2 are both perpendicular to the first straight line L1. The distance between the two second straight lines L2 is greater than the length of the first straight line L1. The first arc C1 protrudes in the direction away from the axis of the rotating shaft, and the second arc C2 protrudes in the direction away from the center of the permanent magnet 203.

[0039] Furthermore, such as Figure 9 As shown, the distance between the two second straight lines L2 is D, the distance from the axis of rotation to the first arc is R (i.e., the radius of the first arc is R), and the number of pole pairs of the permanent magnet is P (the number of pole pairs of one "N" pole permanent magnet and one "S" pole permanent magnet is 1). D, R, and P satisfy: D = n * 2π * R / 2P, 0.80 ≤ n ≤ 0.85. The distance from the highest point of the first arc C1 to the first straight line L1 is T1, and the length of the second straight line L2 is T2. T1 and T2 satisfy: T2 = m * T1, 0.25 ≤ m ≤ 0.30; T1 = k * R, 0.25 ≤ k ≤ 0.30. This technical solution achieves a sinusoidal magnetic field distribution through the design of the shape and size of the permanent magnet 203.

[0040] Furthermore, the length of the first arc line C1 is greater than the arc length corresponding to the cross-section of the arc surface S1, that is, the length of the first arc line C1 is greater than the arc length corresponding to the arc surface S1 in the cross-sectional view.

[0041] Furthermore, the rotor core 202 also includes a rotor yoke 204, such as... Figure 8 As shown, the cross-section of the rotor yoke 204 is a circular ring structure with several notches. The notches are located near the outer edge of the circular ring structure. The notches match the bread-shaped structure, and the radius of the first arc C1 of the bread-shaped structure is greater than the radius R1 of the outer ring of the circular ring structure. The first arc C1 and the circular ring share the same center.

[0042] It is worth mentioning that, Figures 7 to 10 All views are sectional views, where the straight lines and curves represent the surfaces of various components of the permanent magnet brushless motor. For ease of understanding, [the text is incomplete and likely refers to a different view]. Figure 10 The surface represented by each straight line and curve is labeled, such as... Figure 8 , Figure 10 As shown, Figure 8 The outer ring B1 of the circular structure described in the text corresponds to... Figure 10 The outer arc surface S2 of the rotor yoke, Figure 8 The first arc C1 in the middle corresponds to Figure 10 The outer arc surface S3 of the permanent magnet.

[0043] Furthermore, a first radial air gap 301 is provided between the toothed portion 102 and the rotor yoke 204, and a second radial air gap 302 is provided between the toothed portion 102 and the permanent magnet 203. The radius of the first arc C1 is larger than the radius R1 of the outer ring of the annular structure, resulting in different sizes for the first radial air gap 301 and the second radial air gap 302. Since the air gap can play a role in magnetic isolation, the larger the air gap, the more difficult it is for magnetic lines of force to pass through. This technical solution reduces the leakage of magnetic field of the permanent magnet by specially designing it, and the motor can generate a magnetic field density with a sine wave waveform when it is working, thereby improving the motor efficiency. More specifically, the first radial air gap 301 is located between the arc surface S1 of the toothed portion 102 and the outer arc surface S2 of the rotor yoke 204, and the second radial air gap 302 is located between the arc surface S1 of the toothed portion 102 and the outer arc surface S3 of the permanent magnet 203.

[0044] Furthermore, such as Figure 3 ,like Figure 10 As shown, the second tooth includes an arc surface S1, two first planes P1 and two second planes P2 symmetrically arranged along the center line of the arc surface. The first plane P1 is smoothly connected to the arc surface S1. The two ends of the second plane P2 are smoothly connected to the first plane P1 and the first tooth 1021, respectively. The distance between the end of the second plane P2 near the first plane P1 and the arc surface S1 is smaller than the distance between the end of the second plane P2 near the first tooth 102 and the arc surface S1.

[0045] Furthermore, the stator core 101 and / or rotor core 202 are composed of multiple layers of electromagnetic steel plates.

[0046] Furthermore, the coil winding 103 is arranged around the first tooth portion 1021. The stator assembly 100 is a multi-phase centralized stator winding.

[0047] like Figure 12 As shown, the efficiency of the permanent magnet brushless motor described in this embodiment is about 99%, while the efficiency of most existing permanent magnet brushless motors on the market is 97%. The efficiency of the permanent magnet brushless motor described in this embodiment is improved by about 2%.

[0048] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A permanent magnet brushless motor, characterized in that, include: Stator assembly, which includes stator core and coil windings; A rotor assembly includes a rotating shaft and a rotor core disposed on the rotating shaft, the rotor assembly being disposed within the stator assembly, and the rotor assembly and the stator assembly sharing a common central axis; The stator core has an annular yoke and several teeth extending toward the central axis based on the annular yoke. The coil winding is arranged around the teeth. The end of the teeth facing the central axis is an arc surface. The teeth include a first tooth near the annular yoke and a second tooth near the rotor assembly that has an arc surface. The width of the portion of the second tooth near the rotor assembly is greater than the width of the first tooth. The rotor core is provided with a number of permanent magnets arranged alternately with "N" and "S" poles, and the magnetic field lines of each pole of the permanent magnet converge at the point inside the second tooth. The permanent magnet has a bread-shaped cross-section, which includes a first arc, a first straight line sharing a center line with the first arc, two second arcs symmetrically arranged on both sides of the center line and connected to the ends of the first straight line, and two second straight lines symmetrically arranged on both sides of the center line and connected to the ends of the first arc. Both second straight lines are perpendicular to the first straight line, and the distance between the two second straight lines is greater than the length of the first straight line. The first arc protrudes in a direction away from the axis of rotation, and the second arcs protrude in a direction away from the center of the permanent magnet. The distance between the two second straight lines is D, the distance from the axis of rotation to the first arc is R, and the number of pole pairs of the permanent magnet is P. D, R, and P satisfy: D = n 2π R / 2P, 0.80≤n≤0.85; The distance from the center of the rotating shaft to the first arc is R, the distance from the highest point of the first arc to the first straight line is T1, and the length of the second straight line is T2. T1 and T2 satisfy: T2 = m T1, 0.25≤m≤0.30; T1=k R, 0.25 ≤ k ≤ 0.

30.

2. The permanent magnet brushless motor according to claim 1, characterized in that, The length of the first arc is greater than the arc length corresponding to the cross-section of the arc surface.

3. The permanent magnet brushless motor according to claim 1, characterized in that, The rotor core also includes a rotor yoke, the cross-section of which is a circular ring structure with several notches. The notches are located near the outer edge of the circular ring structure. The notches match the bread-shaped structure and the radius of the first arc of the bread-shaped structure is greater than the radius of the outer ring of the circular ring structure. The first arc and the circular ring are concentric.

4. The permanent magnet brushless motor according to claim 3, characterized in that, A first radial air gap is provided between the tooth and the rotor yoke, and a second radial air gap is provided between the tooth and the permanent magnet.

5. The permanent magnet brushless motor according to claim 1, characterized in that, The second tooth includes an arc surface, two first planes and two second planes symmetrically arranged along the center line of the arc surface. The first planes are smoothly connected to the arc surface, and the two ends of the second planes are smoothly connected to the first planes and the first tooth, respectively. The distance between the end of the second plane closer to the first plane and the arc surface is smaller than the distance between the end of the second plane closer to the first tooth and the arc surface.

6. The permanent magnet brushless motor according to claim 1, characterized in that, The stator core and / or rotor core are composed of multiple layers of electromagnetic steel plates.

7. The permanent magnet brushless motor according to claim 1, characterized in that, The coil winding is arranged around the first tooth.

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