BRUSHLESS MOTOR AND ROTOR THEREOF

The application relates a brushless motor and a rotor thereof. The rotor of the brushless motor comprises a rotor core, multiple first magnets for generating first magnetic fields in a radial direction of the rotor core, and multiple second magnets for generating second magnetic fields in a tangential direction of the rotor core; and the multiple first magnets and the multiple second magnets are alternately arranged one by one in a circumferential direction of the rotor core, so that the first magnetic fields and the second magnetic fields are mixed to form a hybrid magnetic field. The rotor can reduce electromagnetic noise of the motor and provides a counter electromotive force with better sinusoidal degree, which can satisfy requirements of FOC drive, reduce the cost of the motor, improve the performance of the motor, and reduce the weight of the motor.

TECHNICAL FIELD

The application relates to motors, and more particularly, relates to a brushless motor and a rotor thereof.

BACKGROUND

Magnets of rotors of brushless motors in the related art usually generate only a magnetic field in a radial direction or a magnetic field in a tangential direction, The magnetic field distributions are shown inFIG.1andFIG.2, and the magnetic field distribution at the end in the presence of the magnetic field in the radial direction only is shown inFIG.3.

SUMMARY OF THE INVENTION

Technical Problem

Normally, such brushless motors generally have the defects of electromagnetic noise and poor counter electromotive force, which are unable to satisfy the requirements of FOC (field-oriented control) drive, and have a high manufacturing cost.

Solution to the Problem

Technical Solution

The technical problem to be solved by the application is to provide an improved brushless motor and a rotor thereof.

The technical solution the application adopts to solve the technical problem is to construct a rotor of a brushless motor, which includes a rotor core, multiple first magnets for generating first magnetic fields in a radial direction of the rotor core, and multiple second magnets for generating second magnetic fields in a tangential direction of the rotor core. The multiple first magnets and the multiple second magnets are alternately arranged one by one in a circumferential direction of the rotor core so that the first magnetic fields and the second magnetic fields are mixed to form a hybrid magnetic field.

Preferably, the first magnets and the second magnets are all bar shaped magnets.

Each of the first magnets has a first width direction and a first thickness direction perpendicular to the first width direction; the first width direction is perpendicular to the radial direction of the rotor core, and the first thickness direction is perpendicular to the tangential direction of the rotor core.

Each of the second magnets has a second width direction and a second thickness direction perpendicular to the second width direction.

The second width direction is perpendicular to the tangential direction of the rotor core, and the second thickens direction is perpendicular to the tangential direction of the rotor core.

Preferably, the rotor core is configured as a hollow structure with a hollow space extending through two ends of the rotor core.

Multiple first limiting slots in one-to-one correspondence with the multiple first magnets are formed in an inner wall surface of the rotor core.

Preferably, multiple second limiting slots in one-to-one correspondence with the multiple second magnets are formed in the inner wall surface of the rotor core.

The multiple first limiting slots and the multiple second limiting slots are alternately arranged one by one in the circumferential direction of the rotor core.

Preferably, a housing is further provided to be sleeved around an outside of the rotor core.

Preferably, positioning structures are arranged on the housing and the rotor core.

The positioning structures comprise a bulge arranged on an outer wall surface of the rotor core and protruding in the radial direction, and a positioning groove formed in an inner wall surface of the housing and corresponding to the bulge.

Preferably, a rotary shaft is further provided, with two ends of the rotary shaft extending out of the rotor core.

The housing includes a body, an opening formed at one end of the body to allow for insertion of the rotor core into the body, and a through hole formed in the other end of the housing to allow the rotary shaft to extend out.

Preferably, an anti-slip sleeve is further provided, which is arranged in the through hole and sleeved around the rotary shaft.

Preferably, surfaces, facing each other, of two of the second magnets located on two opposite sides of each of the first magnet are identical in magnetic polarity.

Surfaces, facing the rotary shaft, of two of the first magnets located on two opposite sides of each of the second magnet are opposite in magnetic polarity.

The present application further provides a brushless motor, including the rotor of the present application, and a stator assembled with the rotor.

Beneficial Effects of the Invention

Beneficial Effects

Implementing the brushless motor and the rotor thereof of the application has the following beneficial effects: multiple first magnets capable of generating first magnetic fields in a radial direction of a rotor core of the rotor and multiple second magnets capable of generating second magnetic fields in a tangential direction of the rotor core are arranged on the rotor core, and the multiple first magnets and the multiple second magnets are alternately arranged one by one in a circumferential direction of the rotor core, so that the first magnetic fields and the second magnetic fields are mixed to form a hybrid magnetic field. The rotor can thus reduce electromagnetic noise of the motor, provide a counter electromotive force with better sinusoidal degree, satisfy the requirements of FOC drive, reduce the cost of the motor, improve the performance of the motor, and reduce the weight of the motor.

PREFERRED EMBODIMENT FOR IMPLEMENTING THE INVENTION

Preferred Embodiment of the Invention

To gain a better understanding of the technical features, purposes and effects of the application, specific embodiments of the application are described in detail herein with reference to accompanying drawings.

FIG.4illustrates some preferred embodiments of a brushless motor according to the application. The brushless motor has the advantages of low noise, good performance and light weight.

As shown inFIG.4, in some embodiments, the brushless motor may include a rotor and a stator assembled with the rotor. The rotor may include a rotor core10, a first magnet20and a second magnet30. The rotor core10may be cylindrical in shape. There can be provided with multiple such first magnets20that are arranged at intervals in a circumferential direction of the rotor core20, and each first magnet20may generate a first magnetic field in a radial direction of the rotor core10. There can be provided with multiple such second magnets30that are arranged at intervals in the circumferential direction of the rotor core10, and each second magnet30may generate a second magnetic field in a tangential direction of the rotor core10. The first magnetic fields and the second magnetic fields may be mixed to form a hybrid magnetic field. By adopting the hybrid magnetic field, the magnetism gathering ability of the motor can be effectively improved; low-grade magnets can be used to obtain the performance of high-grade magnets, so the motor of the same power level has a lighter weight, higher efficiency and lower cost, and the electromagnetic noise of the brushless motor can be greatly lowered; and the present application can guarantee a lower cogging torque of the motor, reduce a torque ripple of the motor, and increase the NVH value of the motor, while reducing the weight of the motor, thereby improving the market competitiveness and expanding the application range of the motor, and hence bringing good economic benefit and social significance.

As shown inFIG.5-FIG.8, further, in some embodiments, the rotor core10is configured as a hollow structure with a hollow space extending through two ends of the rotor core10, and may include a cylindrical body11, a first limiting slot12and a second limiting slot13. The cylindrical body11may be made from silicon steel sheets by stamping. Multiple inner teeth may be arranged at intervals on an inner side of the cylindrical body11, with one first limiting slot12or one second limiting slot13formed between each two adjacent inner teeth. The first limiting slot12is used to limit the first magnet20, and the second limiting slot13is used to limit the second magnet30. By means of the first limiting slot12and the second limiting slot13, the problem of falling of the magnet can be solved. The magnet is generally mounted on the surface of the rotor of the brushless motor or is inserted into the rotor, and particularly for external-rotor motors, most of which adopt the magnet mounted on the surface of the rotor and generally use a seamless tube as a magnetic yoke of the rotor to provide a magnetic field path, it can be difficult to bond the magnet on the rotor. The magnet often falls especially in harsh application scenarios, leading to a failure of the rotor. The first limiting slot12and the second limiting slot13can effectively solve this problem.

In some embodiments, there can be provided with multiple such first limiting slots12, and the first limiting slots12are formed in an inner wall surface of the rotor core10. Specifically, the first limiting slots12may be formed in an inner wall surface of the cylindrical body11and spaced apart from each other in the circumferential direction of the rotor core10. The first limiting slots12may be in one-to-one correspondence with the first magnets20and used to limit the first magnets20to prevent the first magnets20from falling off. Specifically, the first limiting slots12may be bar shaped slots extending through two ends of the rotor core10. A first slot opening is formed at a lateral end of each first limiting slot12to allow for the insertion of the corresponding first magnet20into the first limiting slot12. A first limit flange121is arranged on each of two opposite sides of the first slot opening and extends toward each other to block the corresponding first magnet20, thereby preventing the first magnet20from falling off in the radial direction. In some embodiments, magnet glue may be arranged between the first limiting slot12and the first magnet20to prevent the first magnet20from falling off in case of a high speed and large rotational inertia.

There can be provided with multiple such second limiting slots13, and the second limiting slots13can be formed in the inner wall surface of the rotor core10. Specifically, the second limiting slots13may be formed in the inner wall surface of the cylindrical body11and spaced apart from each other in the circumferential direction of the rotor core10. The second limiting slots13and the first limiting slots12may be alternately arranged in the circumferential direction of the rotor core10. The second limiting slots13may be in one-to-one correspondence with the second magnets30and used to limit the second magnets30to prevent the second magnets30from falling off. Specifically, in some embodiments, the second limiting slots13may be bar shaped slots extending through two ends of the rotor core10. A second slot opening is formed at a lateral end of each second limiting slot13to allow for the insertion of the corresponding second magnet30into the second limiting slot13. A second limit flange131is arranged on each of two opposite sides of the second slot opening and extends toward each other to block the corresponding second magnet30, thereby preventing the second magnet30from falling off in the radial direction. In some embodiments, magnet glue is arranged between the second limiting slot13and the second magnet30to prevent the second magnet30from falling off in case of a high speed and large rotational inertia.

As shown inFIG.9, further, in some embodiments, the first magnet20may be a bar shaped magnet. Specifically, the first magnet20may be rectangular or tile-shaped. The first magnet20may have a first width direction, a first thickness direction and a first length direction. When the first magnets20are assembled in the first limiting slots12, the first width direction may be perpendicular to the radial direction of the rotor core10, the first length direction may be parallel to an axial direction of the rotor core10, and the first thickness direction may be perpendicular to the tangential direction of the rotor core10. In some embodiments, surfaces, facing a rotary shaft50, of two of the first magnets20located at two opposite sides of each of second magnets20are opposite in magnetic polarity.

As shown inFIG.10, further, in some embodiments, the second magnet30may be a bar shaped magnet. Specifically, the second magnet30may be rectangular or tile-shaped. The width of the second magnet30may be less than the width of the first magnet20. The second magnet30may have a second width direction, a second thickness direction and a second length direction. When the second magnets30are assembled in the second limiting slots13, the second width direction may be perpendicular to the tangential direction of the rotor core10, the second thickness direction may be perpendicular to the tangential direction of the rotor core10, and the second length direction may be perpendicular to the axial direction of the rotor core10. In some embodiments, surfaces, facing each other, of two of the second magnets30located at two opposite sides of each of the first magnets20are identical in magnetic polarity.

As shown inFIG.7andFIG.11, further, in some embodiments, the rotor of the brushless motor may further include a housing40. The housing40may be sleeved around an outside of the rotor core10. The housing40may be made from a die-cast aluminium alloy, which can enclose the rotor core10and realize dynamic balance of the rotor by removal of material to improve the quality and production efficiency of the motor. In some embodiments, the housing40may include a body41, an opening42and a through hole43. The body41may be cylindrical in shape, the opening42may be formed at one end of the body41, and a heat dissipation structure may be arranged at the other end of the body42. The through hole43may be formed in the other end of the body41. Specifically, the through hole43may be coaxial with the opening42and located in the middle of the heat dissipation structure, and the radial size of the through hole43may be less than the radial size of the opening42. In some embodiments, positioning structures are arranged on the housing40and the rotor core10. The positioning structures can prevent the housing40and the rotor core10from becoming separated from each other in case of a large torque and high speed. In some embodiments, the positioning structures may include a bulge14and a positioning groove411, and the bulge14may be arranged on an outer wall surface of the rotor core10. Specifically, the bulge14may be located on an outer wall surface of the cylindrical body11. There can be provided with multiple such bulges14that are arranged at intervals in the circumferential direction of the rotor core10and may protrude from the outer wall surface of the rotor core10in the radial direction of the rotor core10. The positioning groove411may be formed in an inner wall surface of the housing40. Specifically, in some embodiments, the positioning groove411may be formed in an inner wall surface of the body41. There can be provided with multiple such positioning grooves411that are arranged at intervals in the circumferential direction of the rotor core10and correspond to the bulges14. When the housing40and the rotor core10are assembled together, the bulges14may be engaged in the positioning grooves411, such that the housing40and the rotor core10are prevented from becoming separated from each other.

Further, in some embodiments, the rotor of the brushless motor may further include the rotary shaft50. The rotary shaft50may be used to output power, and two ends of the rotary shaft50may extend out of the rotor core10via the opening42and the through hole43, respectively.

Further, in some embodiments, the rotor of the brushless motor may further include an anti-slip sleeve60. The anti-slip sleeve60may be arranged in the through hole43and sleeved around the rotary shaft60to prevent the rotary shaft50from falling off from the housing40or slipping under a high speed and large torque.

The magnetic field distribution of the brushless motor is shown inFIG.12andFIG.13, and the counter electromotive force of the brushless motor is shown inFIG.14. As can be seen, the magnetic field distribution of the brushless motor is uniform, and the counter electromotive force of the brushless motor has a good sinusoidal degree, and therefore the requirements of FOC drive can be satisfied.

It should be understood that the above embodiments are specifically described in detail to express several preferred implementations of the application, and should not be construed as limitations to the patent scope of the application. It should be pointed out that people with ordinary skill in the art can freely combine the above technical features and make some transformations and improvements without departing from the concept of the application, and all these combinations, transformations and improvements should fall within the protection scope of the application. Therefore, all equivalent transformations and modifications made according to the scope of the claims of the application should fall within the scope of the claims of the application.