Motor rotor and brushless motor

Abstract

This invention discloses a motor rotor, comprising an axially extending shaft, a rotor core fixed to the shaft, and a plurality of magnets located within the rotor core. The rotor core has an axially extending shaft hole and magnet holes, with the shaft passing through the shaft hole and the magnets housed within the magnet holes. The motor rotor includes a first balance block located at one axial end of the rotor core. The first balance block has a receiving cavity facing the rotor core and a cantilever located within the receiving cavity, the cantilever abutting against the axial end face of the magnets. By defining the internal structure of the first balance block, this invention can compensate for errors in the axial pressing of the motor rotor, thereby improving the axial accuracy of the motor.

Description

[Technical Field]

[0001] This invention relates to the field of motor technology, and in particular to a motor rotor and a brushless motor with relatively small magnet pressing error. [Background Technology]

[0002] Brushless DC motors, as small and highly efficient motors, are increasingly widely used in various fields and are favored by major industries. Currently, a brushless motor consists of a rotor and a stator fitted around the outside of the rotor. The rotor includes a shaft, rotor core, magnets, and balance weights. The balance weights are generally located on one or both sides of the rotor core along its axial direction. During the manufacturing process, assembly issues can lead to dynamic balance errors in the rotor. To address these errors, the balance weights need to be trimmed to reduce their weight and ensure the brushless motor's balance. However, errors can occur during the axial pressing of the brushless motor, requiring adjustments to the balance weights, rotor height, or fan height, resulting in a large workload, high cost, and low production efficiency.

[0003] Therefore, it is indeed necessary to provide an improved motor rotor and brushless motor to overcome the shortcomings of the prior art. [Summary of the Invention]

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a motor rotor and brushless motor that can compensate for axial pressing errors and reduce costs.

[0005] The present invention solves the problems of the prior art by adopting the following technical solution: a motor rotor, comprising an axially extending shaft, a rotor core fixed on the shaft, and a plurality of magnets located within the rotor core. The rotor core is provided with an axially extending shaft hole and magnet holes located on the outer periphery of the shaft hole. The shaft passes through the shaft hole, and the magnets are housed within the magnet holes. The motor rotor includes a first balance block located at one axial end of the rotor core. The first balance block is provided with a receiving cavity facing the rotor core and a cantilever located within the receiving cavity. The cantilever abuts against the axial end face of the magnets.

[0006] A further improvement is as follows: the cantilever extends circumferentially within the receiving cavity and has a protrusion at its free end, the protrusion protruding from the axial end face of the first balance block and abutting against the magnet.

[0007] A further improvement is as follows: the rotor core is provided with a third through hole that runs through the rotor core axially, and the third through hole is connected to the receiving cavity.

[0008] A further improvement is as follows: the first balance block is provided with a first through hole on the outer circumference surface. The first through hole is connected to the receiving cavity. When the rotor core rotates, air passes through the third through hole, the receiving cavity and the first through hole in sequence.

[0009] A further improvement is as follows: The motor rotor includes a second balance block located at the other axial end of the rotor core. The second balance block has a second through hole that extends through the second balance block along the axial direction. The second through hole is connected to the third through hole. When the rotor core rotates, air passes through the second through hole, the third through hole, the receiving cavity, and the first through hole in sequence.

[0010] A further improvement is as follows: the motor rotor also includes a fan fixed on the rotating shaft, the first balance block is located between the rotor core and the fan, and the fan rotates to generate airflow.

[0011] A further improvement is that the motor rotor also includes a fan integrally formed with the first balance block, and the fan rotates to generate airflow.

[0012] A further improvement is as follows: a brushless motor, including a motor rotor and a motor stator sleeved on the outer periphery of the motor rotor, wherein the first balance block is at least partially exposed at one axial end of the motor stator.

[0013] A further improvement is as follows: The motor stator includes a stator core sleeved on the outer periphery of the rotor core and a winding wound on the stator core. The stator core is provided with several teeth extending radially inward and a winding slot located between adjacent teeth. The winding is wound on the teeth and housed in the winding slot.

[0014] Compared with the prior art, the present invention has one or more of the following beneficial effects:

[0015] 1. A first balance block is provided at one axial end of the rotor core. The first balance block has a receiving cavity facing the rotor core and a cantilever located in the receiving cavity. The cantilever abuts against the axial end face of the magnet, which can compensate for the axial pressing error of the motor rotor, thereby improving the axial accuracy of the motor.

[0016] 2. The cantilever extends circumferentially within the receiving cavity and has a protrusion at its free end. The protrusion protrudes from the axial end face of the first balance block and abuts against the magnet, which can further compensate for the axial pressing error of the motor rotor and improve the axial accuracy of the motor.

[0017] 3. The rotor core is provided with a third through hole that penetrates the rotor core along the axial direction and the third through hole is connected to the receiving cavity. The first balance block is provided with a first through hole located on the outer circumferential surface and the first through hole is connected to the receiving cavity. When the rotor core rotates, air passes through the third through hole, the receiving cavity and the first through hole in sequence, which can improve the heat dissipation effect of the motor rotor and help improve the performance of the motor rotor.

[0018] 4. The motor rotor includes a second balance block located at the other axial end of the rotor core. The second balance block has a second through hole that passes through the second balance block along the axial direction. The second through hole is connected to the third through hole. When the rotor core rotates, air passes through the second through hole, the third through hole, the receiving cavity and the first through hole in sequence, which can further improve the dynamic balance error and improve the heat dissipation effect. [Attached Image Description]

[0019] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings:

[0020] Figure 1 This is a three-dimensional schematic diagram of a brushless motor in a preferred embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A three-dimensional schematic diagram of the motor rotor in the brushless motor shown;

[0022] Figure 3 yes Figure 1 The exploded view of the brushless motor shown.

[0023] Figure 4 yes Figure 3 A three-dimensional schematic diagram of the first balancing block shown;

[0024] Figure 5 yes Figure 4 The longitudinal cross-sectional view of the first balancing block shown;

[0025] Figure 6 yes Figure 3 A three-dimensional schematic diagram of the first balancing block from another angle;

[0026] Figure 7 This is a three-dimensional schematic diagram of a second embodiment of the second balancing block of the present invention;

[0027] Figure 8 This is a three-dimensional schematic diagram of the second embodiment of the third through hole on the rotor core of the present invention;

[0028] Figure 9 This is a three-dimensional schematic diagram of the third embodiment of the third through hole on the rotor core of the present invention;

[0029] Figure 10 This is a perspective view of the second embodiment of the fan of the present invention;

[0030] Figure 11 This is a cross-sectional view of the brushless motor of the present invention.

[0031] Meaning of the reference numerals in the diagram:

[0032] 100. External rotor motor 1. Motor rotor 2. Motor stator

[0033] 10. Shaft; 20. Rotor core; 21. Shaft hole

[0034] 22. Magnet hole; 23. Third through hole; 30. Magnet.

[0035] 40. First counterweight; 41. Receiving cavity; 42. Cantilever.

[0036] 421, Protrusion 43, First through hole 50, Second balance block

[0037] 51. Second through hole; 60. Fan; 71. Stator core

[0038] 72. Winding 73. Tooth 74. Winding slot

Detailed Implementation Methods

[0039] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Please see Figure 1As shown, the embodiments of the present invention relate to an electric motor, specifically a brushless motor 100 that can be used in power tools. The brushless motor 100 includes a motor rotor 1, a motor stator 2 sleeved on the outer periphery of the motor rotor 1, and a fan 60. The fan 60 is fixed to one axial end of the motor rotor 1. When the brushless motor 100 is working, the motor rotor 1 can drive the fan 60 to rotate relative to the motor stator 2.

[0043] Please see Figures 2 to 3 As shown, the motor rotor 1 includes an axially extending shaft 10, a rotor core 20 fixed on the shaft, and several magnets 30 located within the rotor core 20. The rotor core 20 has an axially extending shaft hole 21 and magnet holes 22. The shaft 10 passes through the shaft hole 21, and the magnets 30 are wholly or partially housed within the magnet holes 22. In this embodiment, there are four magnet holes 22, which are evenly distributed radially outside the shaft hole 21; there are four magnets 30, each housed within a corresponding magnet hole 22 with a fitting gap between them.

[0044] In this invention, the number of magnet holes 22 and magnets 30 is not limited, nor is the position of the magnet holes 22 and magnets 30 limited. The magnet holes 22 may or may not be on the same circumference; this is not a limitation. The magnet 30 may have a tile-like structure and may be made of neodymium iron boron material. Of course, the structure of the magnet 30 may also be annular, and the magnet material is not limited to neodymium iron boron material.

[0045] Please see Figures 3 to 6 As shown, the motor rotor 1 includes a first balance block 40 located at one axial end of the rotor core 20. The material of the first balance block includes one or more of alloy and plastic, which is used to offset the dynamic balance of the rotor. To ensure balance, for larger rotors, the balance block is made of alloy, and for smaller rotors, it is made of plastic. This not only achieves a better dynamic balance effect, but also maintains a reasonable cost.

[0046] Furthermore, the first balance block 40 is provided with a receiving cavity 41 facing the rotor core and a cantilever 42 located within the receiving cavity. The cantilever 42 abuts against the axial end face of the magnet 30, which can compensate for the axial pressing error of the motor rotor, thereby improving the axial accuracy of the motor. The cantilever 42 extends circumferentially within the receiving cavity 41 and is provided with a protrusion 421 at its free end. The protrusion 421 protrudes from the axial end face of the first balance block 40 and abuts against the magnet 30, which can further compensate for the axial pressing error of the motor rotor and improve the axial accuracy of the motor. In this invention, the number of receiving cavities 41 is not limited; it can be the same as or different from the number of magnet holes, as long as it can solve the axial pressing error of the motor rotor and improve the axial accuracy of the motor.

[0047] The rotor core 20 is provided with a third through hole 23 extending axially through the rotor core. The third through hole 23 is connected to the receiving cavity 41. The third through hole 23 is at least one of the gap formed between the magnet hole 22 and the magnet 30 and a through hole independent of the magnet hole 22. The first balance block 40 is provided with a first through hole 43 located on its outer circumferential surface. The first through hole 43 is connected to the receiving cavity 41. When the rotor core 20 rotates, air passes through the third through hole 23, the receiving cavity 41, and the first through hole 43 in sequence, which can improve the heat dissipation effect of the motor rotor and is beneficial to improving the performance of the motor rotor. In this invention, the number of third through holes 23 is not limited. It can be the same as the number of magnet holes or different from the number of magnet holes, as long as it can improve the heat dissipation effect of the motor rotor.

[0048] The motor rotor includes a second balance block 50 located at the other axial end of the rotor core 20. The second balance block 50 has a second through hole 51 extending axially through it, and the second through hole 51 connects to the third through hole 23. When the rotor core rotates, air passes sequentially through the second through hole 51, the third through hole 23, the receiving cavity 41, and the first through hole 43, which can further improve dynamic balance error and heat dissipation. Please refer to [link / reference]. Figure 7 In another preferred embodiment of the second balance block 50 of the present invention, the shape of the second through hole 51 can also be a groove, as long as it can satisfy the requirement that air passes through the second through hole 51, the third through hole 23, the receiving cavity 41 and the first through hole 43 in sequence when the rotor core rotates.

[0049] Please see Figures 8 to 9 The image shown is a cross-sectional view of the rotor core 20. The rotor core 20 has a third through hole 23 extending axially through the rotor core; the shape of this hole is not limited and can be anything from [specific type to more specific type]. Figure 8 The elliptical shape in the middle can also be Figure 9The semicircle in the figure can also be any shape, size, and number of third through holes not shown in the figure, as long as it can achieve the air outlet effect. The number is, for example, but not limited to, 1, 2, 5, or 8.

[0050] Please see Figure 10 As shown, the motor rotor also includes a fan 60 integrally formed with the first balance block 40, the fan rotating to generate airflow. The integrally formed fan 60 is preferably made of thermosetting plastic via injection molding; thermosetting plastic is also known as bulk molding compound (BMC). The integral forming of the first balance block 40 and the fan 60 simplifies the manufacturing process of the brushless motor 100 and increases the mechanical strength of the first balance block 40, thereby improving the performance of the brushless motor 100.

[0051] Fans have blade geometry parameters, where blade profile refers to the geometric shape of the cross-section of the blade along the airflow direction. The main performance indicator of a two-dimensional blade profile is the lift-to-drag ratio. The pressure, power loss, and efficiency of a cooling fan are related to the lift, drag, and lift-to-drag ratio of the blade profile, respectively. Fan blades, also called blades, have three cross-sectional shapes: airfoil, curved, and straight-edge. Curved and straight-edge blades are simple in shape and easy to manufacture, and their performance can meet the basic requirements of cooling fans. Airfoil blades, whose cross-sectional shape is inspired by aircraft wings, are mostly used in the field of aero-engines. Their application in the field of cooling fans can also bring high aerodynamic and noise performance, but they are relatively difficult to manufacture, the strength of the blade tip is difficult to guarantee, and the cost is high. The parameters of curved and straight-edge structures are relatively simple, while the geometric parameters of airfoil blades are more complex. The blade in this invention belongs to the straight-edge blade mentioned here.

[0052] Please see Figure 11 As shown, the motor stator 2 includes a stator core 71 sleeved on the outer periphery of the rotor core and a winding 72 wound on the stator core 71. The stator core 71 is provided with a plurality of teeth 73 extending radially inward and a winding groove 74 located between adjacent teeth. The winding 72 is wound on the teeth 73 and housed in the winding groove 74.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A motor rotor, comprising an axle extending in an axial direction, a rotor core fixed on the axle, and a plurality of magnetic steels located in the rotor core, the rotor core being provided with an axle hole extending in the axial direction and a magnetic steel hole located at the periphery of the axle hole, the axle being arranged in the axle hole, and the magnetic steels being arranged in the magnetic steel hole; characterized in that: The motor rotor comprises a first balance block at one axial end of the rotor core, the first balance block is provided with a receiving cavity facing the rotor core and a cantilever in the receiving cavity, the cantilever abuts against an axial end surface of the magnetic steel; The rotor core is provided with a third through hole penetrating the rotor core along the axial direction, the third through hole is communicated with the receiving cavity; The first balance block is provided with a first through hole on the outer circumferential surface, the first through hole is communicated with the receiving cavity, and air passes through the third through hole, the receiving cavity and the first through hole in sequence when the rotor core rotates.

2. The electrical machine rotor of claim 1, wherein: The cantilever extends in the circumferential direction in the receiving cavity and is provided with a protrusion at the free end, the protrusion protrudes from the axial end surface of the first balance block and abuts against the magnetic steel.

3. The motor rotor of claim 1, wherein: The third through hole is at least one of a gap formed between the magnetic steel hole and the magnetic steel and a through hole independent of the magnetic steel hole.

4. The motor rotor of claim 1, wherein: The motor rotor comprises a second balance block at the other axial end of the rotor core, the second balance block is provided with a second through hole penetrating the second balance block along the axial direction, the second through hole is communicated with the third through hole, and air passes through the second through hole, the third through hole, the receiving cavity and the first through hole in sequence when the rotor core rotates.

5. The motor rotor of claim 1, wherein: The motor rotor further comprises a fan fixed to the rotating shaft, the first balance block is located between the rotor core and the fan, and the fan rotates to generate airflow.

6. The motor rotor of claim 1, wherein: The motor rotor further comprises a fan integrally formed with the first balance block, and the fan rotates to generate airflow.

7. A brushless motor comprising a motor rotor and a motor stator which is fitted to the outer circumference of the motor rotor, characterized by: The motor rotor is the motor rotor of any one of claims 1 to 6, and the first balance block is at least partially exposed to one axial end of the motor stator.

8. The brushless motor of claim 7, wherein: The motor stator comprises a stator core sleeved on the outer periphery of the rotor core and a winding wound on the stator core, the stator core is provided with a plurality of tooth portions extending radially inward and wire grooves between adjacent tooth portions, and the winding is wound on the tooth portions and accommodated in the wire grooves.

Images