An electric bicycle hub motor rotor structure

Abstract

The application provides an electric bicycle hub motor rotor structure, comprising a hub, an inner ring coaxially arranged in the hub, and a ring of magnet assemblies uniformly arranged on the annular wall surface of the inner ring in the circumferential direction; the magnet assembly comprises a magnet concentrating shell fixed with the inner ring and a permanent magnet used in cooperation with the magnet concentrating shell, two adjacent magnet concentrating shells are in contact with each other, and the side end portions of the plurality of magnet concentrating shells are flush; the magnet concentrating shell is a one-side opening closed box body, the permanent magnet is arranged in the magnet concentrating shell, one magnetic pole of the permanent magnet is shielded by the magnet concentrating shell, and the other magnetic pole of the permanent magnet is exposed to the opening of the magnet concentrating shell; the magnetic pole of each permanent magnet exposed to the opening of the magnet concentrating shell points to the center of the inner ring, and the magnetic poles of two adjacent permanent magnets exposed to the opening of the magnet concentrating shell are opposite; the electric bicycle hub motor rotor structure has the multiple effects of improving the magnetic density, reducing the cost, improving the stability and the like.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically to a hub motor rotor structure for driving electric bicycles. Background Technology

[0002] Embedded permanent magnet synchronous motors, with their advantages of high efficiency, wide speed range, and excellent structural reliability, are widely used in high-end equipment fields such as electric bicycle hub motors and industrial drives.

[0003] In existing conventional embedded permanent magnet motor structures, the permanent magnets are directly embedded in the permanent magnet slots of the rotor core, with the bottom of the permanent magnets in direct contact with the high-permeability rotor core. There is no effective magnetic isolation structure, resulting in severe bottom magnetic leakage and magnetic short-circuiting defects. A large amount of permanent magnet flux does not participate in the effective work done in the air gap, but instead forms a short-circuit magnetic circuit through the rotor core, significantly reducing the utilization rate of the air gap magnetic flux density. This defect directly causes insufficient effective output torque of the motor and rapid efficiency decay under high-speed, weak-field conditions.

[0004] To compensate for magnetic flux loss, existing solutions generally improve motor performance by increasing the amount of rare earth permanent magnets. This not only leads to increased overall material costs and waste of rare earth resources, but also exacerbates local magnetic concentration in permanent magnets due to magnetic circuit disorder and high operating temperatures, significantly increasing the risk of high-temperature demagnetization and reducing the stability and lifespan of the motor.

[0005] The existing structure has problems such as low magnetic energy utilization, poor power performance, low high-speed energy efficiency, high cost and insufficient high-temperature reliability, which cannot meet the application requirements of high-end equipment for high performance, low cost and high reliability of permanent magnet motors. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of this, the present invention provides a rotor structure for an electric bicycle hub motor, which has multiple effects such as improving magnetic flux density, reducing cost, and improving stability.

[0008] (II) Technical Solution

[0009] To solve the aforementioned technical problem, the present invention provides a rotor structure for an electric bicycle hub motor, including a hub, an inner ring coaxially disposed within the hub, and a ring of magnet assemblies uniformly arranged along the circumferential direction on the annular wall surface of the inner ring; the magnet assembly includes a magnetic shell fixed to the inner ring and permanent magnets that cooperate with the magnetic shell, two adjacent magnetic shells abutting against each other, and the side ends of multiple magnetic shells being flush; the magnetic shell is a closed box with an opening on one side, the permanent magnets are placed inside the magnetic shell, one magnetic pole of the permanent magnet is shielded by the magnetic shell, and its other magnetic pole is exposed in the opening of the magnetic shell; the magnetic pole of each permanent magnet exposed in the opening of the magnetic shell points to the center of the inner ring, and the magnetic poles of two adjacent permanent magnets exposed in the opening of the magnetic shell are opposite.

[0010] This solution, through the combination of a magnetic shell and a permanent magnet, can increase the magnetic field strength of the exposed magnetic poles, while also shielding the magnetic field interference of nearby magnets, thereby improving the torque and speed of the motor. It enables the motor to have higher air gap magnetic flux density and torque density in a smaller volume, and can also generate reluctance torque, further improving the motor torque density and effectively reducing the motor volume, thus improving motor performance. At the same time, it reduces the volume of the permanent magnet while maintaining a constant magnetic force, thereby reducing costs.

[0011] In some embodiments, the magnetic housing is adsorbed onto the wall of the inner ring by the permanent magnet, and then the magnetic housing and the permanent magnet are fixed to the hub by anaerobic adhesive. This solution not only facilitates the installation of the magnet assembly, but also ensures a firm connection between the magnet assembly and the inner ring, preventing the magnet assembly from falling off during use and guaranteeing its service life.

[0012] In some embodiments, the distance between the side end of the magnetic shell and the edge of the inner ring is 2 mm to 10 mm.

[0013] In some embodiments, the magnetic housing is provided with heat dissipation grooves, which communicate with the inner cavity of the magnetic housing for heat dissipation of the permanent magnet. This design allows heat within the permanent magnet to be dissipated through the heat dissipation grooves, which helps to reduce the operating temperature of the magnet assembly and extend its service life.

[0014] In some embodiments, the magnetic shell includes an annular closed frame disposed around the periphery of the permanent magnet and a closed wall for closing one end of the annular closed frame, the closed wall and the opening being arranged opposite to each other, and one magnetic pole of the permanent magnet facing the closed wall.

[0015] In some embodiments, the enclosed wall and the annular enclosed frame are an integral structure and are made of a soft magnetic material.

[0016] In some embodiments, the wall thickness of the magnetic housing is 10% to 50% of the height of the magnet assembly. This solution allows for adjustment and enhancement of the constant torque and constant speed of the motor by adjusting the thickness of the magnetic housing.

[0017] In some embodiments, the number of magnet assemblies is an even number, and the number of magnet assemblies is at least four.

[0018] In some embodiments, the shape of the magnetic shell is adapted to the shape of the permanent magnet; the magnetic shell is rectangular, and the permanent magnet is a rectangular tile-like structure.

[0019] In some embodiments, the permanent magnet is one of neodymium iron boron magnets, samarium cobalt magnets, and alnico magnets.

[0020] (III) Beneficial Effects

[0021] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0022] 1) By enclosing the permanent magnet with a magnetic shell, leaving only one magnetic pole exposed, the magnetic flux generated by the enclosed magnetic pole is refracted by the magnetic shell and directed towards the opening of the magnetic shell. At the same time, since the magnetic field lines are closed curves, the refracted magnetic flux will extend and return to the other magnetic pole, thereby increasing the magnetic field strength of the exposed magnetic pole. It can also shield the magnetic field interference of nearby magnets, improve the torque and speed of the motor, and enable it to have higher air gap magnetic flux density and torque density in a smaller volume. It can also generate reluctance torque, further improving the torque density of the motor, and can effectively reduce the size of the motor, thus improving the performance of the motor.

[0023] 2) After being shielded and refracted by the magnetic shell, the magnetism of the shielded surface of the permanent magnet is weakened and the magnetic flux is reduced, while the magnetism of the other exposed surface of the permanent magnet is enhanced and the magnetic flux is increased. Therefore, the volume of the permanent magnet can be reduced while maintaining a constant magnetic force, thereby reducing costs and improving the utilization rate of rare earth resources, or the volume of the permanent magnet can be kept unchanged while increasing its magnetism to improve performance. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a perspective view of the rotor structure of an electric bicycle hub motor according to the present invention;

[0026] Figure 2This is a schematic diagram of the rotor structure of an electric bicycle hub motor according to the present invention;

[0027] Figure 3 This is a perspective view of the hub in the rotor structure of an electric bicycle hub motor according to the present invention;

[0028] Figure 4 This is a cross-sectional view of the connection between the hub and the magnet assembly in the rotor structure of an electric bicycle hub motor according to the present invention;

[0029] Figure 5 This is a perspective view of the magnet assembly in the rotor structure of an electric bicycle hub motor according to the present invention;

[0030] Figure 6 This is a cross-sectional view of the magnet assembly in the rotor structure of an electric bicycle hub motor according to the present invention;

[0031] Figure 7 This is an exploded view of the magnet assembly in the rotor structure of an electric bicycle hub motor according to the present invention;

[0032] Figure 8 This is a perspective view of the magnetic shell in the rotor structure of an electric bicycle hub motor according to the present invention;

[0033] The component names corresponding to the various labels in the figure are: 1. Hub; 101. Inner ring; 2. Magnet assembly; 21. Magnetizing shell; 22. Permanent magnet; 211. Heat dissipation groove; 212. Annular closed frame; 213. Closed wall; 214. Inner cavity; 215. Side end. Detailed Implementation

[0034] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0035] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0037] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0038] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0039] Combination Figures 1-8 As shown, the present invention provides a rotor structure for an electric bicycle hub motor, mainly used for driving electric bicycles. It includes a hub 1, and an inner ring 101 is coaxially arranged inside the hub 1. Multiple magnet components 2 are installed on the inner ring 101, that is, a ring of magnet components 2 is evenly arranged along the circumferential direction on the annular wall surface of the inner ring 101.

[0040] like Figure 1 , Figure 2 , Figure 4 and Figure 5 As shown, each magnet assembly 2 includes a magnetic shell 21 fixed to the inner ring 101 and a permanent magnet 22 that cooperates with the magnetic shell 21. Two adjacent magnetic shells 21 abut against each other, and the side ends 215 (upper or lower ends) of multiple magnetic shells 21 are flush, that is, the upper ends of multiple magnetic shells 21 are in the same plane, and the lower ends of multiple magnetic shells 21 are also in the same plane. The magnetic shell 21 is a closed box with an opening on one side, and the closed box has an inner cavity 214 for accommodating the permanent magnet 22. The permanent magnet 22 is placed inside the magnetic shell 21, one magnetic pole of the permanent magnet 22 is shielded by the magnetic shell 21, and the other magnetic pole of the permanent magnet 22 is exposed in the opening of the magnetic shell 21; the magnetic pole of each permanent magnet 22 exposed in the opening of the magnetic shell 21 points to the center of the inner ring 101, and the magnetic poles of two adjacent permanent magnets 22 exposed in the opening of the magnetic shell 21 are opposite.

[0041] In the rotor structure of this electric bicycle hub motor, the magnet assembly 2, through the cooperation of a magnetic shell 21 and a permanent magnet 22, utilizes the law of refraction of magnetic field lines, namely, "when magnetic flux enters another medium from one medium, if the permeability of the two media is different, the magnetic induction intensity will undergo refraction, just like sound waves and light waves, and the magnetic induction intensity will change direction." The permanent magnet is enclosed by the magnetic shell, leaving only one magnetic pole exposed. The magnetic flux generated by the enclosed magnetic pole is refracted by the magnetic shell and directed towards the opening of the magnetic shell. At the same time, because the magnetic field lines are closed curves, the refracted magnetic flux will extend and return to the other magnetic pole, thereby increasing the magnetic field strength of the exposed magnetic pole. It can also shield the magnetic field interference of nearby magnets, thereby improving the torque and speed of the motor.

[0042] The rotor structure of this electric bicycle hub motor employs a combination of a magnetic shell 21 and a permanent magnet 22, enabling it to achieve higher air gap magnetic flux density and torque density within a smaller volume. It also generates reluctance torque, further improving the motor's torque density and effectively reducing its size, thus enhancing motor performance. Furthermore, after being shielded and refracted by the magnetic shell, the magnetism on the shielded side of the permanent magnet weakens, reducing magnetic flux, while the magnetism on the exposed side strengthens, increasing magnetic flux. This allows for a reduction in the permanent magnet's volume while maintaining a constant magnetic force, lowering costs and improving rare earth resource utilization. Alternatively, it allows for increasing the magnetism while keeping the permanent magnet's volume constant, thereby improving performance.

[0043] In some embodiments, such as Figures 1 to 4 As shown, the magnetic housing 21 is attracted to the wall of the inner ring 101 by the permanent magnet 22, and then the magnetic housing 21 and the permanent magnet 22 are fixed to the hub 1 by anaerobic adhesive. That is, during assembly, the permanent magnet 22 is first placed inside the magnetic housing 21, and then the magnetic housing 21 is attached to the inner ring 101. The magnetic housing 21 is attracted to the wall of the inner ring 101 by the magnetism of the permanent magnet 22. Then, multiple magnetic components 2 are sequentially attached to the inner ring 101 in the above manner. After the magnetic components 2 have covered a full ring, adhesive is applied. Anaerobic adhesive can be used to fix the magnetic housing 21 and the permanent magnet 22 to the hub 1. This structure not only facilitates the installation of the magnetic components 2, but also ensures a firm connection between the magnetic components 2 and the inner ring 101, preventing the magnetic components 2 from falling off during use and ensuring service life.

[0044] In some embodiments, such as Figure 4 As shown, the distance between the side end 215 of the magnetic housing 21 and the edge of the inner ring 101 is 2mm to 10mm. That is, the distance L between the upper end of the magnetic housing 21 and the upper edge of the inner ring 101 is 2mm to 10mm, and the distance between the lower end of the magnetic housing 21 and the lower edge of the inner ring 101 is different from L and is also 2mm to 10mm, which can be selected according to the requirements.

[0045] In some embodiments, such as Figure 5 , Figure 7 and Figure 8 As shown, heat dissipation grooves 211 are symmetrically arranged on both sides of the magnetic housing 21. The heat dissipation grooves 211 are connected to the inner cavity 214 of the magnetic housing 21 for heat dissipation of the permanent magnet 22. When the motor is running, a large amount of heat is easily accumulated in the permanent magnet 22, and the magnetic housing 21 seals the permanent magnet 22, making it even more difficult for the heat to dissipate. This structure, with heat dissipation grooves 211 on the magnetic housing 21, allows the heat inside the permanent magnet 22 to be dissipated through the heat dissipation grooves 211, which helps to reduce the operating temperature of the magnet assembly 2 and extend its service life.

[0046] In some embodiments, such as Figure 7 and Figure 8 As shown, the magnetic shell 21 includes an annular closed frame 212 arranged around the outer periphery of the permanent magnet 22 and a closed wall 213 for closing one end of the annular closed frame 212. The closed wall 213 and the opening are arranged opposite to each other. One magnetic pole of the permanent magnet 22 is exposed to the opening, and the other magnetic pole of the permanent magnet 22 faces the closed wall 213. The heat dissipation groove 211 is arranged on the annular closed frame 212.

[0047] In some embodiments, such as Figure 7 and Figure 8 As shown, the closed wall 213 and the annular closed frame 212 are an integral structure and are made of soft magnetic material.

[0048] In some embodiments, such as Figure 6 As shown, the wall thickness of the magnetic housing 21 is 10% to 50% of the height of the magnet assembly 2. The maximum torque of the motor is directly proportional to the wall thickness of the magnetic housing, and the maximum speed of the motor is inversely proportional to the wall thickness of the magnetic housing. By adjusting the thickness of the magnetic housing, the constant torque and constant speed of the motor can be adjusted and enhanced, or the volume of the permanent magnet can be reduced to reduce the weight of the motor and the cost of the magnet.

[0049] In some embodiments, the number of magnet components 2 is an even number, and the number of magnet components 2 is at least four.

[0050] In some embodiments, such as Figure 7 and Figure 8 As shown, the shape of the magnetic shell 21 is adapted to the shape of the permanent magnet 22. In this embodiment, the magnetic shell 21 is rectangular, and the permanent magnet 22 has a rectangular tile-like structure.

[0051] In some embodiments, the permanent magnet 22 is one of a neodymium iron boron magnet, a samarium cobalt magnet, and an alnico magnet.

[0052] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0053] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A rotor structure for an electric bicycle hub motor, comprising a hub (1), wherein an inner ring (101) is coaxially disposed within the hub (1), characterized in that: A ring of magnet assemblies (2) is evenly arranged along the circumferential direction on the annular wall of the inner ring (101); the magnet assembly (2) includes a magnetic shell (21) fixed to the inner ring (101) and a permanent magnet (22) used in conjunction with the magnetic shell (21). Two adjacent magnetic shells (21) abut against each other, and the side ends (215) of multiple magnetic shells (21) are flush; the magnetic shell (21) is a closed box with an opening on one side, and the permanent magnet (22) is placed inside the magnetic shell (21). One magnetic pole of the permanent magnet (22) is shielded by the magnetic shell (21), and its other magnetic pole is exposed in the opening of the magnetic shell (21); the magnetic pole of each permanent magnet (22) exposed in the opening of the magnetic shell (21) points to the center of the inner ring (101), and the magnetic poles of two adjacent permanent magnets (22) exposed in the opening of the magnetic shell (21) are opposite.

2. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The magnetic shell (21) is adsorbed onto the wall of the inner ring (101) by the permanent magnet (22), and then the magnetic shell (21) and the permanent magnet (22) are fixed on the hub (1) by anaerobic adhesive.

3. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The distance between the side end (215) of the magnetic shell (21) and the edge of the inner ring (101) is 2 mm to 10 mm.

4. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The magnetic shell (21) is provided with a heat dissipation groove (211), which is connected to the inner cavity (214) of the magnetic shell (21) for heat dissipation of the permanent magnet (22).

5. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The magnetic shell (21) includes an annular closed frame (212) arranged around the outer periphery of the permanent magnet (22) and a closed wall (213) for closing one end of the annular closed frame (212). The closed wall (213) and the opening are arranged opposite to each other, and one magnetic pole of the permanent magnet (22) faces the closed wall (213).

6. The rotor structure of the electric bicycle hub motor according to claim 5, characterized in that: The closed wall (213) and the annular closed frame (212) are an integral structure and are made of soft magnetic material.

7. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The wall thickness of the magnetic shell (21) is 10% to 50% of the height of the magnet assembly (2).

8. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The number of magnet components (2) is an even number, and the number of magnet components (2) is at least four.

9. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The shape of the magnetic shell (21) is adapted to the shape of the permanent magnet (22); the magnetic shell (21) is rectangular and the permanent magnet (22) is a rectangular tile structure.

10. The rotor structure of the electric bicycle hub motor according to claim 1, characterized in that: The permanent magnet (22) is one of neodymium iron boron magnet, samarium cobalt magnet and alnico magnet.

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