Compact hub motor

Abstract

The utility model relates to a compact hub motor. The compact hub motor comprises a shell assembly, a middle shaft, a stator assembly and a rotor assembly, the middle shaft is arranged in the shell assembly in a penetrating mode. The stator assembly and the rotor assembly are arranged in an inner space enclosed by the shell assembly, and the stator assembly and the rotor assembly are arranged at intervals in the axial direction of the middle shaft to form an axial magnetic flux path; the stator assembly comprises a stator fixing piece and a winding, the stator fixing piece is fixedly connected with the middle shaft, and the winding is directly or indirectly fixed on the stator fixing piece and is rotationally and symmetrically arranged around the axis of the stator assembly; the rotor assembly comprises a rotor fixing piece and permanent magnets, the rotor fixing piece is rotationally connected with the middle shaft through a bearing, the rotor fixing piece is directly or indirectly fixedly connected with the shell assembly, the permanent magnets are rotationally and symmetrically arranged around the axis of the rotor assembly, and the magnetic poles, facing the stator assembly, of the adjacent permanent magnets are opposite. The motor is compact in structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of small-sized electric machines, and in particular to a compact wheel hub motor. BACKGROUND

[0002] A wheel hub motor for electric bicycle is disclosed in Chinese patent CN101856948A, which comprises a main shaft, a wheel hub shell mounted on the main shaft through a wheel hub shell bearing, a motor and a planetary gear reduction mechanism for driving the wheel hub shell to rotate, which are all installed in the wheel hub shell. The motor adopts an outer stator and inner rotor structure, the stator is fixed on the inner wall of the wheel hub shell and can rotate with the wheel hub shell, and the rotor is connected with the planetary gear reduction mechanism.

[0003] The stator and rotor of the outer stator and inner rotor motor are both cylindrical, the stator surface is provided with a stator slot, and an armature winding is embedded in the stator slot. Because the stator core is a part of the main magnetic circuit of the stator and rotor, the stator core structure is not easy to compress. In addition, the rotor is assembled inside the stator, and the assembly structure and magnetic field air gap make the inner and outer diameters and axial length of the stator and rotor have a certain gap, so that the structure of the motor stator and rotor is not compact enough. CONTENT OF THE UTILITY MODEL

[0004] In order to make the structure of the motor stator and rotor more compact, thereby reducing the overall size of the motor, the present application provides a compact wheel hub motor.

[0005] The compact wheel hub motor provided by the present application adopts the following technical scheme:

[0006] The compact wheel hub motor comprises a shell assembly, a middle shaft, a stator assembly and a rotor assembly. The middle shaft is arranged in the shell assembly. The stator assembly and the rotor assembly are arranged in an internal space enclosed by the shell assembly, and the stator assembly and the rotor assembly are arranged axially along the middle shaft to form an axial magnetic flux path. The stator assembly comprises a stator fixing member and a winding. The stator fixing member is fixedly connected with the middle shaft. The winding is directly or indirectly fixed on the stator fixing member and is arranged rotationally symmetrically around the axis of the stator assembly. The rotor assembly comprises a rotor fixing member and a permanent magnet. The rotor fixing member is rotatably connected with the middle shaft through a bearing. The rotor fixing member is directly or indirectly fixedly connected with the shell assembly. The permanent magnet is arranged rotationally symmetrically around the axis of the rotor assembly, and adjacent permanent magnets face opposite poles of the stator assembly.

[0007] By the technical scheme, the stator assembly and the rotor assembly are arranged axially and spaced apart along the middle shaft, the space between the stator assembly and the rotor assembly is a magnetic field gap, the magnetic field is axially distributed, and the stator yoke is not a path of main magnetic flux, so the stator yoke can be omitted, even the stator core can be omitted, and the axial length of the motor stator and rotor is greatly reduced. Meanwhile, due to the axial assembly of the stator assembly and the rotor assembly, the difference between the inner and outer diameters of the stator assembly and the inner and outer diameters of the rotor assembly is greatly reduced, so that the overall structure of the motor stator and rotor is more compact.

[0008] Optionally, the rotor assembly is provided with two groups, and the stator assembly is arranged between the two groups of rotor assemblies.

[0009] The motor structure is designed as a single-stator double-rotor structure, the stator and rotor are symmetrical, there are double-sided air gaps, and the axial magnetic pulling force between the motor stator and rotor is reduced. In addition, due to the symmetrical overall structure, the mass distribution of the motor is more uniform, and the riding experience is better after being installed on a power-assisted bicycle hub.

[0010] Optionally, the winding includes a core and a coil, and the coil is wound around the core.

[0011] Optionally, the winding includes a printed conductor, and the printed conductor is printed on the end face of the rotor fixing member facing the rotor assembly.

[0012] Optionally, the printed conductor is one of a fan ring structure, a circular structure, a trapezoidal structure, or a rhombic structure.

[0013] The printed circuit board structure winding omits the structure of the stator core, further reducing the axial length of the motor stator and rotor. In addition, the printed circuit board structure can also reduce the hysteresis and eddy current loss caused by the stator core, and improve the power density of the motor.

[0014] Optionally, the housing assembly includes a first housing and a second housing, the first housing and the second housing enclose an enclosed internal space, the first housing includes a side plate and a cover plate, the cover plate is provided with a boss at the center position, and the cover plate is provided with a reinforcing component.

[0015] Optionally, one end of the reinforcing component extends to the side of the boss, and the other end extends to the outer edge of the cover plate.

[0016] Optionally, the boss is a hollow cylindrical structure, and the side of the boss is provided with threads.

[0017] Optionally, the boss is provided with a boss positioning hole, the reinforcing component is provided with a positioning groove arranged radially along the cover plate, and the end of the reinforcing component close to the outer edge of the cover plate is provided with a cover plate positioning hole.

[0018] By setting the slot hole on the shell assembly, the shell of the wheel hub motor is clamped and fixed during the assembly process, which is suitable for different types of tool clamps. The reinforcing part is added on the cover plate to reduce the deformation or damage of the shell assembly during assembly.

[0019] In summary, the present application includes at least one of the following beneficial technical effects:

[0020] The stator assembly and the rotor assembly are arranged axially along the central axis, so that the main magnetic field of the motor is distributed axially, which can reduce the axial length of the motor stator and rotor;

[0021] The motor structure with single stator and double rotors is symmetrical in overall structure, and the mass distribution is uniform, which reduces the axial magnetic pull of the motor;

[0022] The stator assembly adopts printed circuit board structure, which removes the stator core structure and reduces the iron loss, so that the overall efficiency of the motor is higher. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the overall structure of a compact wheel hub motor in embodiment 1 of the present application.

[0024] Figure 2 is a structure sectional view of a compact wheel hub motor in embodiment 1 of the present application.

[0025] Figure 3 is a schematic diagram of the overall structure of the first shell in embodiment 1 of the present application.

[0026] Figure 4 is an exploded view of the stator assembly in embodiment 1 of the present application.

[0027] Figure 5 is a schematic diagram of the overall structure of a compact wheel hub motor in embodiment 2 of the present application.

[0028] Figure 6 is a structure sectional view of a compact wheel hub motor in embodiment 2 of the present application.

[0029] Figure 7 is a schematic diagram of the stator assembly in embodiment 2 of the present application.

[0030] Explanation of reference signs: 100, housing assembly; 110, first housing; 111, side plate; 112, cover plate; 113, boss; 1131, boss positioning hole; 114, reinforcing component; 1141, positioning groove; 1142, cover plate positioning hole; 120, second housing; 200, middle shaft; 201, wire outlet hole; 300, stator assembly; 310, first stator fixing plate; 320, core; 330, coil; 340, second stator fixing plate; 350, base plate; 360, printed conductor; 400, rotor assembly; 410, rotor fixing plate; 420, permanent magnet. DETAILED DESCRIPTION

[0031] The following description will be made in conjunction with the accompanying drawings. Figures 1-7 The present application will be further described in detail.

[0032] The present application discloses a compact wheel hub motor. Embodiment 1

[0033] Reference Figure 1 and Figure 2 A compact wheel hub motor comprises a housing assembly 100, a middle shaft 200, a stator assembly 300 and a rotor assembly 400. The housing assembly 100 encloses a closed internal space, which is fixedly connected with the hub of a power-assisted bicycle. The middle shaft 200 is arranged in the housing assembly 100 and extends out of the housing assembly 100 at both ends to be fixedly connected with the frame of the power-assisted bicycle. The stator assembly 300 and the rotor assembly 400 are arranged inside the housing assembly 100 and connected with the middle shaft 200. In this embodiment, two sets of rotor assemblies 400 are arranged, the stator assembly 300 and the two sets of rotor assemblies 400 are distributed along the axial direction of the middle shaft 200, and the stator assembly 300 is arranged between the two sets of rotor assemblies 400.

[0034] Reference Figure 2 and Figure 3The shell assembly 100 comprises a first shell 110 and a second shell 120 which constitute a closed internal space by bolt connection. The first shell 110 comprises an integrally formed side plate 111 and a cover plate 112. The side plate 111 is enclosed in a cylindrical structure, and the cover plate 112 is arranged on the end face side of the side plate 111. The cover plate 112 is generally circular, and a boss 113 is formed near the center of the cover plate 112. A plurality of boss positioning holes 1131 are arranged on the end face of the boss 113 and are rotationally symmetrical about the axis of the cover plate 112. A plurality of reinforcing components 114 are arranged radially on the outer surface of the cover plate 112. In this embodiment, the reinforcing component 114 comprises two parallel reinforcing ribs, and a positioning groove 1141 is formed between the two reinforcing ribs. The first end of the reinforcing component 114 extends to the side of the boss 113, and the second end extends beyond the outer edge of the cover plate 112. A cover plate positioning hole 1142 is formed at the position where the reinforcing component 114 extends beyond the outer edge of the cover plate 112. The second shell 120 has a similar structure to the cover plate 112, and details are not repeated here.

[0035] Optionally, the first end of the reinforcing component 114 does not extend to the side of the boss 113. The boss 113 is cylindrical, and a thread is arranged on the circumferential side of the boss 113 to facilitate connection of the first shell 110 with other components.

[0036] The middle shaft 200 passes through the center of the boss 113. The middle shaft 200 and the shell assembly 100 can be connected by an oil seal to achieve the sealing of the internal space of the shell assembly 100. An outlet hole 201 can be arranged in the middle shaft 200 for installing a wire harness. One end of the outlet hole 201 communicates with the outside, and the other end communicates with the internal space of the shell assembly 100.

[0037] Referring to Figure 2 and Figure 4 The stator assembly 300 comprises a first stator fixing plate 310, a winding, and a second stator fixing plate 340. In this embodiment, the winding is a core copper wire winding, which comprises a core 320 and a coil 330. The core 320 is a fan ring structure made of silicon steel sheets, and a plurality of cores 320 are arranged rotationally symmetrical about the axis of the stator assembly 300, with gaps between adjacent cores 320. The two ends of the core 320 are fixedly connected with the first stator fixing plate 310 and the second stator fixing plate 340, respectively. The connection between the core 320, the first stator fixing plate 310, and the second stator fixing plate 340 can be direct or indirect, and can be fixedly connected or not fixedly connected. The coil 330 is wound around the circumferential side of the core 320. The first stator fixing plate 310 and the second stator fixing plate 340 are fixedly sleeved on the middle shaft 200, so that the stator assembly 300 is fixedly connected with the middle shaft 200.

[0038] The rotor assembly 400 comprises a rotor fixing plate 410 and permanent magnets 420. The rotor fixing plate 410 is connected with the middle shaft 200 through a bearing, and the rotor fixing plate 410 can rotate around the middle shaft 200. The side of the rotor fixing plate 410 facing the stator assembly 300 is provided with a plurality of permanent magnets 420, which are rotationally symmetrically arranged around the axis of the rotor assembly 400, and the adjacent permanent magnets 420 are oppositely arranged in magnetic poles; for example, one of the permanent magnets 420 has an N pole facing one end of the stator assembly 300, and the adjacent permanent magnet 420 has an S pole facing one end of the stator assembly 300. The permanent magnets 420 can be made of one of the materials of aluminum-nickel-cobalt, ferrite, samarium-cobalt, and neodymium-iron-boron. The rotor fixing plate 410 is directly or indirectly fixed and press-fitted in the inside of the housing assembly 100, so that the housing assembly 100 is fixedly connected with the rotor assembly 400.

[0039] The external power supply supplies power to the stator assembly 300 through a wire harness. Since the stator assembly 300 is opposite to the end face of the rotor assembly 400, the magnetic flux path is emitted from the N pole of the permanent magnet 420, passes through the air gap formed by the axial gap between the stator assembly 300 and the rotor assembly 400, the stator assembly 300, and the S pole of the permanent magnet 420, and forms an axially distributed magnetic field. Compared with the radial distribution of the magnetic flux path, the motor structure in the present application has a shorter axial length, and the inner and outer diameters of the stator assembly 300 and the rotor assembly 400 are similar, so the overall structure is compact. In the embodiment of the present application, two rotor assemblies 400 are used, and the motor can be designed as a symmetrical structure, and the overall weight is uniform. The housing assembly 100 and the rotor assembly 400 are fixedly connected, and the bearing is no longer arranged between the housing assembly 100 and the middle shaft 200, thereby reducing the assembly parts of the motor. Embodiment 2

[0040] With reference to Figure 5 and Figure 6 A compact hub motor comprises a housing assembly 100, a middle shaft 200, a stator assembly 300, and a rotor assembly 400. The housing assembly 100 encloses a closed internal space, which is fixedly connected with the hub of a power-assisted bicycle. The middle shaft 200 is arranged in the housing assembly 100 and extends out of the housing assembly 100 to be fixedly connected with the frame of the power-assisted bicycle. The stator assembly 300 and the rotor assembly 400 are arranged inside the housing assembly 100 and connected with the middle shaft 200. In this embodiment, two rotor assemblies 400 are arranged, and the stator assembly 300 and the two rotor assemblies 400 are spaced apart along the axial direction of the middle shaft 200, and the stator assembly 300 is arranged between the two rotor assemblies 400.

[0041] Different from embodiment 1, the stator assembly 300 of embodiment 2 comprises a substrate 350, and the substrate 350 is fixedly connected with the middle shaft 200. The substrate 350 is a double-sided printed circuit substrate, and printed conductors 360 are etched on both sides of the substrate 350. The printed conductors 360 are rotationally symmetrically arranged around the axis of the stator assembly 300.

[0042] With reference to Figure 7 a-d, the single printed conductor 360 can be a fan ring structure, a circular structure, a trapezoidal structure, or a diamond structure. The stator assembly 300 thus constitutes a PCB coreless stator, which further reduces the axial length compared to Embodiment 1, and the overall structure of the motor is more compact.

[0043] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, so: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A compact wheel hub motor, characterized by: The application relates to a motor, which comprises a shell assembly, a middle shaft, a stator assembly and a rotor assembly. The middle shaft is arranged in the shell assembly, the stator assembly and the rotor assembly are arranged in an internal space enclosed by the shell assembly, and the stator assembly and the rotor assembly are arranged axially along the middle shaft to form an axial magnetic flux path. The stator assembly comprises a stator fixing member and a winding, the stator fixing member is fixedly connected with the middle shaft, the winding is directly or indirectly fixed on the stator fixing member, and the winding is arranged in rotational symmetry around the axis of the stator assembly. The rotor assembly comprises a rotor fixing member and permanent magnets, the rotor fixing member is rotatably connected with the middle shaft through a bearing, the rotor fixing member is directly or indirectly fixedly connected with the shell assembly, the permanent magnets are arranged in rotational symmetry around the axis of the rotor assembly, and adjacent permanent magnets face poles of the stator assembly in opposite directions.

2. A compact wheel hub motor according to claim 1, characterized in that: The rotor assembly is provided with two groups, and the stator assembly is arranged between the two groups of rotor assemblies.

3. The compact wheel hub motor of claim 1, wherein: The winding comprises an iron core and a coil, and the coil is wound around the side of the iron core.

4. The compact wheel hub motor of claim 1, wherein: The winding comprises printed wires, and the printed wires are printed on the end face of the rotor fixing member facing the rotor assembly.

5. A compact wheel hub motor according to claim 4, characterized in that: The printed wires are in one of a fan ring structure, a circular structure, a trapezoidal structure or a diamond structure.

6. The compact wheel hub motor of claim 1, wherein: The shell assembly comprises a first shell and a second shell, the first shell and the second shell enclose an enclosed internal space, the first shell comprises a side plate and a cover plate, the cover plate is provided with a boss at a center position, and the cover plate is provided with a reinforcing member.

7. A compact wheel hub motor according to claim 6, characterized in that: One end of the reinforcing member extends to the side of the boss, and the other end extends to the outer edge of the cover plate.

8. The compact wheel hub motor of claim 6, wherein: The boss is in a hollow cylindrical structure, and the side of the boss is provided with threads.

9. The compact wheel hub motor of claim 6, wherein: The boss is provided with a boss positioning hole, the reinforcing member is provided with a positioning groove arranged in a radial direction of the cover plate, and the reinforcing member is provided with a cover plate positioning hole at one end close to the outer edge of the cover plate.

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