Iron-core-free wheel hub driving motor

Abstract

The invention relates to the technical field of motors, in particular to a coreless hub driving motor which comprises a stator assembly, a rotor assembly and a bearing part, the stator assembly comprises a stator disc and a stator lining, the rotor assembly comprises a rotor disc, the number of layers of the stator disc is at least more than one, and the number of the rotor disc is at least more than two. The stator discs and the rotor discs are arranged in a staggered manner in the axial direction of the motor; the bearing part comprises a bearing outer ring and a bearing inner ring, the radial inner end of the stator disc is fixedly installed on the stator lining, the stator lining is installed on the bearing outer ring, and the radial inner end of the rotor disc is installed on the bearing inner ring. The electric vehicle wheel driving system can meet the special requirement for electric vehicle wheel driving, the energy conversion efficiency, the response speed and the control precision of the motor are improved, and meanwhile the system adapts to limited space and weight limitation in wheels.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and particularly to a coreless hub drive motor. Background Art

[0002] With the development of fields such as electric vehicles, higher requirements are put forward for aspects such as the performance, space utilization, and efficiency of motors. Traditional motors have certain limitations in structure and performance. For example, core motors have core eddy current losses and hysteresis losses, resulting in limited energy conversion efficiency; they are relatively large in volume and weight, and are not suitable enough in some application scenarios with strict space and weight requirements (such as automotive wheel drives); the response speed and control accuracy are not ideal enough, etc. Therefore, a new type of motor is needed to overcome these problems and meet the high-performance drive requirements.

[0003] In view of this, the present invention provides a coreless hub drive motor. Summary of the Invention

[0004] The purpose of the present invention is to provide a coreless hub drive motor in view of the deficiencies of the prior art.

[0005] To solve the above technical problems, the following technical solutions are adopted: A coreless hub drive motor includes a stator assembly and a rotor assembly. The stator assembly includes a stator disk, and the rotor assembly includes a rotor disk. The number of layers of the stator disk is at least one layer or more, and the rotor disk is at least two layers or more. The stator disk and the rotor disk are arranged alternately in the axial direction of the motor; The rotor assembly further includes a rotor connector. The inside of the rotor connector is connected with the rotor disk. A first limiting component is provided between the rotor connector and the rotor disk, and the first limiting component is used to limit the radial rotation between the rotor connector and the rotor disk; Both ends on the outer side of the rotor connector are connected with a second limiting component. Adjacent rotor disks are connected together through the second limiting component, and the second limiting component is used to limit the radial movement between the rotor connector and the rotor disk; The rotor disk includes a yoke disk and magnetic steel sheets. There are multiple magnetic steel sheets, and the magnetic steel sheets are evenly distributed on the yoke disk in a circular matrix manner. The radially outer end of the yoke disk is connected to the rotor connector. The magnetic steel sheets on adjacent rotor disks limit the axial movement between the rotor connector and the rotor disk under the action of the magnetic attraction of the magnets.

[0006] On the basis of the above-described technical solution, a further improvement is that both the stator assembly and the rotor assembly are connected with bearing members. The bearing members include an outer bearing ring and an inner bearing ring. The radially inner end of the stator assembly is fixedly installed on the outer bearing ring, and the radially inner end of the rotor assembly is fixedly installed on the inner bearing ring.

[0007] On the basis of the above-described technical solution, a further improvement is that the first limiting assembly includes a first annular body provided at the radially inner end of the rotor connecting member. The first annular body is provided with grooves for anti-torsion, and the rotor disc is provided with convex grooves matching the grooves. Or the first annular body is provided with protruding keyways for anti-torsion, and the rotor disc is provided with concave key grooves matching the keyways.

[0008] On the basis of the above-described technical solution, a further improvement is that the second limiting assembly includes annular protrusions and annular grooves provided on both sides of the radially outer end of the rotor connecting member. The annular protrusions are provided at one outer end of the rotor connecting member, and the annular grooves are provided at the other outer end of the rotor connecting member. Between adjacent rotor connecting members, the radial movement between the rotor connecting member and the rotor disc is restricted through the matching connection of the annular protrusions and the annular grooves.

[0009] On the basis of the above-described technical solution, a further improvement is that the thickness of a single stator disc is 6 - 10 mm, the thickness of a single rotor disc is 6 - 8 mm, and the distance between adjacent rotor discs is 10 - 12 mm.

[0010] On the basis of the above-described technical solution, a further improvement is that the radially inner end of the yoke disc on one side is fixedly connected with a transition disc, and the transition disc is fixedly connected with the inner bearing ring.

[0011] On the basis of the above-described technical solution, a further improvement is that the magnetic steel sheet is made of a permanent magnet of neodymium iron boron or samarium cobalt hard magnetic material.

[0012] On the basis of the above-described technical solution, a further improvement is that the stator assembly further includes a stator bushing. The stator bushing includes a first stator bushing and a second stator bushing. The inner side surface of the first stator bushing is fixedly installed on the outer bearing ring, the second stator bushing is connected to the stator disc by means of composite welding, and a space for installing the stator disc is formed between the first stator bushing and the second stator bushing.

[0013] On the basis of the above technical solution, a further improvement is that a PCB winding is provided on the stator disk, and the PCB winding is etched with coils through a multi-layer printed circuit board; the stator disk uses epoxy resin, polyimide film or ceramic non-magnetic material as a supporting substrate.

[0014] On the basis of the above technical solution, a further improvement is that the outer diameter of the motor is 380 - 440 mm and the thickness is 20 - 40 mm.

[0015] On the basis of the above technical solution, a further improvement is that a hub bracket is connected to the front end of the bearing member, and a wheel is sleeved outside the hub bracket.

[0016] Due to the adoption of the above technical solution, the following beneficial effects are achieved: The present invention provides a coreless hub drive motor that is efficient, compact, lightweight and has good control performance to meet the special requirements of electric vehicle wheel drive, improve the energy conversion efficiency, response speed and control accuracy of the motor, and at the same time adapt to the limited space and weight limitations inside the wheel.

[0017] The permanent magnets are arranged on the rotor. The permanent magnets are made of hard magnetic materials such as neodymium iron boron (Nd-Fe-B) or samarium cobalt (SmCo), etc., and have high magnetic energy product and high coercivity, and can maintain magnetism for a long time. Since the distance between adjacent rotor disks is relatively small, controlled within 3 - 6 mm. Thus, in the axial direction of the motor, multiple adjacent magnetic steel sheets generate magnetic forces attracting each other under the action of the magnet suction force, and then cooperate with the first limiting component and the second limiting component, so that the entire rotor assembly can be installed and connected together without using mechanical connection methods such as screws and nuts or welding connection methods. Furthermore, for the motor of the present invention, without an external skeleton support (motor end cover), only the stator assembly, rotor assembly and bearing member can complete the design of the entire structure. When current passes through the PCB winding of the stator, a magnetic field is generated, and this magnetic field interacts with the current of the magnetic steel sheets in the rotor to generate Ampere force, which pushes the rotor to rotate. Due to the coreless structure, the rotor has a light mass and a small moment of inertia, and can quickly respond to changes in magnetic field force and achieve rapid rotation.

[0018] Since the motor does not require an external skeleton support and is directly installed on the vehicle wheel, it further saves space and reduces weight. The motor adopts advanced coreless magnetic matrix wedge technology and polymer nano-material technology, changing the structure of traditional motors using silicon steel sheets and wound stators, and realizing the organic combination of new materials, new technologies and new structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings: Figure 1Schematic three-dimensional structure diagram of a coreless hub drive motor according to Embodiment 1 of the present invention.

[0020] Figure 2 Front view structure diagram of a coreless hub drive motor according to Embodiment 1 of the present invention.

[0021] Figure 3 According to Embodiment 1 of the present invention Figure 2 Schematic cross-sectional structure diagram in the A direction.

[0022] Figure 4 Rear view structure diagram of a coreless hub drive motor according to Embodiment 1 of the present invention.

[0023] Figure 5 Side view structure diagram of a coreless hub drive motor according to Embodiment 1 of the present invention.

[0024] Figure 6 Schematic structure diagram of a coreless hub drive motor according to Embodiment 1 of the present invention installed on a wheel.

[0025] Figure 7 Internal structure diagram of a coreless hub drive motor according to Embodiment 1 of the present invention installed on a wheel.

[0026] Figure 8 Front view structure diagram of a coreless hub drive motor according to Embodiment 2 of the present invention.

[0027] Figure 9 According to Embodiment 2 of the present invention Figure 8 Schematic cross-sectional structure diagram in the B direction.

[0028] In the figure: 1 - stator assembly; 2 - rotor assembly; 3 - bearing part; 4 - hub bracket; 5 - wheel.

[0029] 11 - stator disk; 12 - first stator bushing; 13 - second stator bushing.

[0030] 21 - rotor disk; 22 - rotor connecting piece; 23 - transition disk.

[0031] 220 - first annular body; 221 - annular protrusion; 222 - annular groove; 223 - groove; 224 - convex groove; 225 - convex key; 226 - concave key groove 211 - yoke disk; 212 - magnetic steel sheet.

[0032] 31 - bearing outer ring; 32 - bearing inner ring. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer and more explicit, the present invention will be described in detail below through the accompanying drawings and embodiments as a further explanation of the present invention. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0034] Example 1, see Figures 1-7 , a coreless hub drive motor, comprising a stator assembly 1, a rotor assembly 2, and a bearing member 3. The stator assembly 1 consists of a stator disk 11 (number of layers ≥ 1 layer, made of ceramic matrix composite material, thermal conductivity 250 W / (m·K)) and a stator bushing (aluminum alloy 6061-T6, hardness HB95). The rotor assembly 2 includes a rotor disk 21 (≥ 2 layers) and a rotor connecting member 22. The stator disk 11 and the rotor disk 21 are arranged alternately along the axial direction of the motor, and power expansion (power adjustment range 15 - 80 kW) is achieved through modular superposition of "stator + rotor". In this embodiment, the stator disk 11 is provided with 1 layer, and the rotor disk 21 is provided with 2 layers.

[0035] The magnetic field path and working principle are as follows: See Figure 3 , magnetic field closed loop: The magnetic force lines of the N pole of the left rotor disk → pass through the air gap → enter the stator disk → pass through the air gap → reach the S pole of the right rotor disk.

[0036] The magnetic force lines of the N pole of the right rotor disk → pass through the air gap → enter the stator disk → pass through the air gap → reach the S pole of the left rotor disk.

[0037] Torque generation: When the stator winding is energized, the current is affected by the Lorentz force in the magnetic field, pushing the rotor to rotate. The alternating change of the three-phase current realizes field-oriented control through an electronic controller (such as the FOC algorithm) to form a continuous torque.

[0038] The rotor assembly 2 further includes a rotor connecting member. The inside of the rotor connecting member is connected with a rotor disk, and a first limiting component is provided between the rotor connecting member and the rotor disk. The first limiting component is used to limit the radial rotation between the rotor connecting member and the rotor disk.

[0039] Both ends of the outside of the rotor connecting member are connected with a second limiting component. The adjacent rotor disks are connected together through the second limiting component. The second limiting component is used to limit the radial movement between the rotor connecting member and the rotor disk.

[0040] As a further illustration of this embodiment, the rotor disk 21 is composed of a yoke disk 211 (Q235B steel, thickness 2.5 mm) and magnet steel sheets 212 (neodymium iron boron N45SH, residual magnetism 1.43 T, coercive force 1194 kA / m). There are 36 magnet steel sheets in this embodiment, and the 36 magnet steel sheets are evenly distributed in a circular array on the yoke disk, with an adjacent included angle of 10°, forming a 24-pole magnetic circuit system. The outer radial side of the yoke disk is connected to the rotor connecting member 22 by friction welding (rotation speed 2000 rpm, axial pressure 50 kN), and the inner radial side is connected to the transition disk 23, and finally forms a rigid transmission system with the inner ring 32 of the bearing (P4 accuracy). The magnet steel sheets on adjacent rotor disks restrict the axial movement between the rotor connecting member and the rotor disk under the action of the magnet attraction force. Since the distance between adjacent rotor disks is relatively small, it is controlled within 3 - 6 mm. Thus, in the axial direction of the motor, multiple adjacent magnet steel sheets generate an attractive magnetic force under the action of the magnet attraction force, and then cooperate with the first limiting component and the second limiting component, so that the entire rotor assembly can be installed and connected together without mechanical connection methods such as screws and nuts or welding connection methods. Furthermore, for the motor of the present invention, without an external skeleton support (motor end cover), only the stator assembly, the rotor assembly, and the bearing parts can complete the design of the entire structure. When current passes through the PCB winding of the stator, a magnetic field is generated, and this magnetic field interacts with the current of the magnet steel sheets in the rotor to generate an Ampere force, which drives the rotor to rotate. Due to the ironless structure, the rotor has a light mass and a small moment of inertia, and can quickly respond to changes in the magnetic field force and achieve rapid rotation.

[0041] In this embodiment, the inner radial end of the yoke disk is connected to the inner ring 32 of the bearing through the transition disk 23, thereby forming a rigid transmission system. Specifically, referring to Figure 3 , corresponding mounting hole positions are provided between the inner radial end of the yoke disk and the transition disk 23. Six M8 mounting holes (hole diameter φ8.2 mm, circumferential included angle 60°) are evenly distributed in the circumferential direction at the inner radial end of the yoke disk 211, and are fixedly connected to the transition disk 23 by M8×20 socket head cap screws (grade 10.9, tightening torque 35 N·m). The bolt holes are designed with countersunk heads (countersunk hole depth 3 mm) to avoid interference. Similarly, eight M10 mounting holes are evenly distributed in the circumferential direction between the transition disk 23 and the inner ring 32 of the bearing, and are connected by M10×25 socket head cap screws, with a fit tolerance of H7 / k6 to ensure that their coaxiality ≤ 0.05 mm.

[0042] As a further illustration of this embodiment, both the stator assembly and the rotor assembly are connected with bearing parts 3. The bearing parts 3 include an outer ring 31 of the bearing and an inner ring 32 of the bearing. The inner radial end of the stator assembly is fixedly installed on the outer ring of the bearing, and the inner radial end of the rotor assembly is fixedly installed on the inner ring of the bearing.

[0043] The rotor connecting member 22, as a connecting component between the rotor disks 21, mounts and connects the respective rotor disks 21 in parallel, and then at the end position, the entire rotor assembly 2 is connected to the inner ring 32 of the bearing through the transition disk 23, so that the rotor assembly 2 and the inner ring 32 of the bearing can rotate synchronously. The entire structure does not require an external skeleton to be provided, and the rotor connecting member 22 can also serve as an external skeleton and be directly mounted on the vehicle wheel 5, further saving space and reducing weight. This integrated structure is verified by ANSYS modal analysis, and the first natural frequency reaches 1250 Hz, effectively avoiding the motor operating frequency range (50 - 800 Hz). Compared with the traditional design, the overall weight is reduced by 28% (SAEJ1939 standard), the heat dissipation area is increased by 35% (the temperature rise is reduced by 6 °C), and at the same time, the external skeleton is omitted, saving 15 mm of axial space, and significantly improving the utilization rate of the hub space.

[0044] As a further description of this embodiment, the magnet steel sheet 212 is made of neodymium iron boron N45SH (remanent magnetism 1.43 T, coercive force 1194 kA / m) or samarium cobalt Sm2Co17 (Curie temperature 750 °C) hard magnetic material, and is formed into an anisotropic magnet through a magnetic field orientation pressing process (magnetic field strength 1.8 T), and the deviation of the remanent magnetism uniformity is ≤ ±2%.

[0045] As a further description of this embodiment, the first limiting component includes a first annular body 220 provided at the radially inner end of the rotor connecting member. A groove 223 for anti-torsion is provided on the first annular body 220, and a convex groove 224 matching the groove 223 is provided on the rotor disk. The groove 223 and the convex groove 224 adopt an H7 / k6 transition fit (interference amount 0.02 - 0.05 mm) to form an anti-torsion key groove structure (see Figure 2 and Figure 4 ).

[0046] Alternatively, a convex key 225 for anti-torsion is provided on the first annular body 220, and a concave key groove 226 matching the convex key 225 is provided on the rotor disk.

[0047] Through the first limiting component, the radial rotation between the rotor connecting member and the rotor disk is restricted, ensuring the stability of the entire structure when the rotor assembly and the inner ring of the bearing rotate together.

[0048] As a further illustration of this embodiment, the second limiting component includes an annular protrusion 221 and an annular groove 222 disposed on both sides of the outer radial end of the rotor connecting member. The annular protrusion 221 is disposed on the outer end of one side of the rotor connecting member, and the annular groove 222 is disposed on the outer end of the other side of the rotor connecting member. Between adjacent rotor connecting members, the radial movement between the rotor connecting member and the rotor disc is restricted through the mating connection of the annular protrusion 221 and the annular groove 222. The second limiting component is composed of the annular protrusion 221 and the annular groove 222 disposed on both sides. The annular protrusion 221 is disposed on the outer end of one side of the rotor connecting member 22, and the annular groove 222 is disposed on the outer end of the other side of the rotor connecting member 22. The annular protrusion 221 matches the annular groove 222. That is, the rapid positioning and connection of adjacent rotor discs 21 are realized, ensuring the stability of the entire structure when the rotor assembly and the inner ring of the bearing rotate together.

[0049] The bearing member 3 includes an outer bearing ring 31 and an inner bearing ring 32. The inner radial end of the stator disc 11 is fixedly installed on the stator bushing, and the stator bushing is installed on the outer bearing ring 31. The inner radial end of the rotor disc 21 is installed on the inner bearing ring 32. The front end of the bearing member 3 is connected to a hub bracket 4, and a wheel 5 is sleeved outside the hub bracket 4. The bearing member 3 adopts a double-row angular contact ball bearing. Its outer bearing ring 31 and the stator bushing are connected by interference fit (H7 / s6), and the inner bearing ring 32 and the transition disc 23 adopt an H7 / k6 transition fit (coaxiality ≤ 0.05 mm). The stator disc 11 is fastened to the stator bushing by M6×12 socket head cap screws. The manufactured motor is directly installed in the hub of the vehicle wheel 5 to ensure a firm and concentric connection between the rotor and the wheel 5, and a correct connection between the stator and the power supply and control system of the vehicle. The motor does not require an external skeleton support and is directly installed on the vehicle wheel 5, further saving space and reducing weight.

[0050] As a further illustration of this embodiment, the stator assembly further includes a stator bushing. The stator bushing is composed of a first stator bushing 12 (aluminum alloy 6061-T6, hardness HB95) and a second stator bushing 13. The first stator bushing 12 is fixed to the outer bearing ring 31 by interference fit (H7 / s6), and a stator disc installation groove with a width of 12 mm is formed therebetween. This structure is verified by ANSYS static analysis, and the maximum deformation amount ≤ 0.2 mm (under a radial force of 19120 N). The second stator bushing is connected to the stator disc by a composite welding method, and a space for installing the stator disc is formed between the first stator bushing and the second stator bushing.

[0051] The stator disk 11 adopts a three-layer structure: the bottom layer is a 0.1-mm polyimide film (dielectric constant 3.5, breakdown voltage 40 kV / mm), the middle layer is an etched copper foil winding (wire diameter 0.3 mm, copper foil thickness 35 μm), and the top layer is a 1.5-mm ceramic matrix composite material (thermal conductivity 250 W / (m·K)). The PCB winding adopts an acidic copper chloride etching process (temperature 45 ± 2°C, etching rate 1.2 μm / min) to form a multi-layer concentrated winding, with the number of slots per pole per phase q = 1, and the winding resistance ≤ 0.05 Ω (20°C).

[0052] Through testing and verification, compared with the traditional silicon steel sheet design, this stator structure has the following advantages: the winding temperature rise is reduced by 20°C (under IP67 protection), the weight is reduced by 35%, and the insulation life is increased to 5000 hours (180°C thermal aging test). The permanent magnet sheets adopt a Halbach array layout, with a magnetic flux density of 1.2 T, which is 15% higher than the parallel magnetization method, and effectively reduces the cogging torque to below 0.5 N·m (motor speed 3000 rpm).

[0053] As a further description of this embodiment, the motor adopts a flat disk structure, with an outer diameter of 380 - 440 mm, a thickness of 20 - 40 mm, the thickness of a single stator disk 11 is 6 - 10 mm, the thickness of a single rotor disk is 6 - 8 mm, and the distance between adjacent rotor disks is 10 - 12 mm.

[0054] This motor has the following main beneficial effects: 1. High efficiency: The motor has no core eddy current loss and hysteresis loss. Compared with the iron-core permanent magnet synchronous motor of the same level (under the same power and speed conditions), the efficiency can be 2 - 3 percentage points higher, and compared with the asynchronous motor of the same level (under the same power and speed conditions), the efficiency can be 3 - 5 percentage points higher.

[0055] 2. Large starting torque, especially outstanding low-speed large-torque operation ability: The overload resistance is 8 to 10 times that of motors of the same level. Through optimized design, the motor can theoretically withstand an overload of 10 times the rated torque for a short period (5 seconds) without stalling.

[0056] 3. Small volume and light weight: Due to the simple structure, the total weight and volume of the motor are small. Therefore, the weight-to-power ratio and volume-to-power ratio of the motor are high. Especially when applied in the occasion of "large disk diameter ratio", the advantage of high power density is more prominent. The volume is only 1 / 3 to 1 / 5 of that of the synchronous motor of the same level, and the weight can reach 1 / 2 to 1 / 4 of that of the synchronous motor of the same level.

[0057] 4. Flexible and convenient power expansion: The basic components of the motor are only two parts, the stator disk and the rotor disk 21, with a very high degree of modularity. The power can be expanded or adjusted by stacking multiple "stator + rotor" units.

[0058] 5. High efficiency and energy saving: There are no core eddy current losses and hysteresis losses, and the energy conversion efficiency is high. Compared with traditional iron-core motors, the energy-saving effect is remarkable.

[0059] 6. Compact and lightweight: The unique disc structure and ironless design make its axial dimension short, thickness small, volume small, and weight light. It is convenient to install inside the wheel 5, saving space and reducing the overall weight of the vehicle, which is beneficial to improving the vehicle's handling performance and cruising range.

[0060] 7. Quick response and precise control: It has good control characteristics, starts and brakes quickly, responds extremely fast, has a small mechanical time constant, can adjust the speed sensitively, and has high control precision. It is suitable for the precise control requirements of the vehicle to drive the wheel 5 under different driving conditions, such as acceleration, deceleration, turning, etc.

[0061] 8. Good heat dissipation performance: The polymer heat-conducting material helps to dissipate heat, preventing the motor from being affected by overheating and shortening its service life, and improving the reliability and stability of the motor operation.

[0062] 9. The installation between the entire rotor assembly is only completed by limit fitting. The first limit component is used to limit the radial rotation between the rotor connecting piece and the rotor disc; the second limit component is used to limit the radial movement between the rotor connecting piece and the rotor disc; the magnetic steel sheets on adjacent rotor discs are attracted by the magnets (the magnetic steel sheets on adjacent rotor discs have opposite polarities), restricting the axial movement between the rotor connecting piece and the rotor disc. Thus, the connection and cooperation of the entire rotor assembly do not require any mechanical rigid connection. And for the motor of the present invention, without an external skeleton support (motor end cover), only the stator assembly, rotor assembly, and bearing parts are needed to complete the design of the entire structure. When current passes through the PCB winding of the stator, a magnetic field is generated, and this magnetic field interacts with the current of the magnetic steel sheets in the rotor to generate Ampere force, pushing the rotor to rotate.

[0063] Example 2, see Figures 8-9 , the difference from Example 1 is that the number of corresponding rotor discs 21 and stator discs 11 is matched according to the required power, that is, the power is expanded or adjusted by superimposing multiple "stator + rotor" sheets. In this embodiment, the stator disc 11 is provided with 3 layers and the rotor disc 21 is provided with 4 layers. The motor mainly generates a rotational torque through the interaction between the stator and rotor magnetic fields to drive the load, and it is a device that converts electrical energy into mechanical energy (and vice versa as a generator). The basic components of the motor are only the stator and rotor, and the modularity is very high, which can be flexibly and conveniently expanded according to the required power.

[0064] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all covered by the protection scope of the present invention.

Claims

1. A coreless wheel hub drive motor, comprising a stator assembly and a rotor assembly, characterized in that: The stator assembly includes a stator disk, the rotor assembly includes a rotor disk, the number of layers of the stator disk is at least one or more, the number of layers of the rotor disk is at least two or more, and the stator disk and the rotor disk are arranged alternately in the axial direction of the motor; The rotor assembly further includes a rotor connecting piece, the inside of the rotor connecting piece is connected with a rotor disk, and a first limiting component is arranged between the rotor connecting piece and the rotor disk, and the first limiting component is used for restricting the radial rotation between the rotor connecting piece and the rotor disk; Both ends of the outer side of the rotor connecting piece are connected with a second limiting component, and adjacent rotor disks are connected together through the second limiting component, and the second limiting component is used for restricting the radial movement between the rotor connecting piece and the rotor disk; The rotor disk includes a yoke disk and magnetic steel sheets, a plurality of magnetic steel sheets are provided, the magnetic steel sheets are uniformly arranged on the yoke disk in a circular matrix manner, the radial outer end of the yoke disk is connected to the rotor connecting piece, and the magnetic steel sheets on adjacent rotor disks restrict the axial movement between the rotor connecting piece and the rotor disk under the action of the magnetic attraction of the magnets.

2. The coreless wheel hub drive motor according to claim 1, characterized in that: Both the stator assembly and the rotor assembly are connected with bearing parts, the bearing parts include a bearing outer ring and a bearing inner ring, the radial inner end of the stator assembly is fixedly installed on the bearing outer ring, and the radial inner end of the rotor assembly is fixedly installed on the bearing inner ring.

3. The coreless wheel hub drive motor according to claim 1, characterized in that: The first limiting component includes a first annular body arranged at the radial inner end of the rotor connecting piece, and a groove for anti-torsion is arranged on the first annular body, and a convex groove matching with the groove is arranged on the rotor disk; Or a convex key for anti-torsion is arranged on the first annular body, and a concave key groove matching with the convex key is arranged on the rotor disk.

4. The coreless wheel hub drive motor according to claim 1, characterized in that: The second limiting component includes an annular protrusion and an annular groove arranged on both sides of the radial outer end of the rotor connecting piece, the annular protrusion is arranged at one outer end of the rotor connecting piece, the annular groove is arranged at the other outer end of the rotor connecting piece, and between adjacent rotor connecting pieces, through the matching connection of the annular protrusion and the annular groove, the radial movement between the rotor connecting piece and the rotor disk is restricted.

5. The coreless wheel hub drive motor according to claim 1, characterized in that: The thickness of a single stator disk is 6 - 10 mm, the thickness of a single rotor disk is 6 - 8 mm, and the distance between adjacent rotor disks is 10 - 12 mm.

6. The coreless wheel hub drive motor according to claim 1, characterized in that: The magnetic steel sheet is made of a permanent magnet of neodymium iron boron or samarium cobalt hard magnetic material.

7. The coreless wheel hub drive motor according to claim 1, characterized in that: The stator assembly further includes a stator bushing, the stator bushing includes a first stator bushing and a second stator bushing, the inner side surface of the first stator bushing is fixedly installed on the bearing outer ring, the second stator bushing is connected with the stator disk by a composite welding method, and a space for installing the stator disk is formed between the first stator bushing and the second stator bushing.

8. The coreless wheel hub drive motor according to claim 1, characterized in that: A PCB winding is arranged on the stator disk, and the PCB winding is etched with coils through a multi-layer printed circuit board; the stator disk uses epoxy resin, polyimide film or ceramic non-magnetic conductive material as a support substrate.

9. The coreless wheel hub drive motor according to claim 1, characterized in that: The outer diameter of the motor is 380 - 440 mm, and the thickness is 20 - 40 mm.

10. The coreless wheel hub drive motor according to claim 1, characterized in that: The front end of the bearing member is connected to a hub bracket, and a wheel is sleeved outside the hub bracket.

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