Outer rotor brushless direct current hub motor

Abstract

The utility model discloses an outer rotor brushless direct current hub motor, it includes: stator mechanism, it includes fixed frame and sets up the first coupling son on fixed frame frame, the moving mechanism, it includes the rotation circle, sets up the second coupling son on the inner wall of rotation circle, and the rotation circle one end is provided with the bottom plate, under the drive of direct current, based on the electromagnetic interaction of first coupling son with the non -contact mode and the second coupling son, generates the rotation torque on the rotation circle, to make the rotation circle rotate around stator mechanism, rotation axis, and the bottom plate is connected through the planetary gear mechanism to one end of rotation axis, and the other end of rotation axis is used for driving load rotation. The above-mentioned hub motor, through the planetary gear mechanism to the torque that rotation circle produced carries out the effective speed change and the increase of the twist, will the smaller torque that motor produces under the higher rotating speed, through the speed reduction and the increase of the twist conversion is the larger torque and the lower rotating speed suitable for driving load, thereby ensures that motor is in the efficient operation, satisfies the drive requirement of load.

Description

Technical Field

[0001] This utility model relates to the field of DC motor technology, and in particular to an external rotor brushless DC hub motor. Background Technology

[0002] With the increasing demand for fully automated intelligent equipment operating in complex terrains, hub motors, as the core drive component of such mobile vehicles, face the dual challenges of high torque output and miniaturized design.

[0003] In existing technologies, traditional brushless DC hub motors typically employ a direct, rigid connection between the rotor mechanism and the output shaft. For example, the motor rotor (as part of the rotor mechanism) is coaxially fixed to the output shaft via a flange or keyway structure. While this direct-drive structure is relatively simple, it has significant limitations in practical applications. Due to the lack of torque amplification from a transmission mechanism, the motor's output torque is directly limited by its own electromagnetic torque parameters. This leads to insufficient torque in specific scenarios requiring high torque output, such as climbing slopes with gradients greater than 60 degrees, often resulting in the walking mechanism experiencing jamming, slippage, or even stalling. Especially for devices like intelligent robots or fully automated lawnmowers, frequent terrain changes place higher demands on the dynamic torque response capabilities of their hub motors, and the torque output bottleneck of existing structures severely restricts the maneuverability of such devices in complex terrain.

[0004] To address the aforementioned insufficient torque issue, the industry has attempted to increase output torque by increasing motor size or boosting input current. However, these improvements often lead to a significant increase in motor weight and energy consumption, contradicting the design requirements of lightweight and high-efficiency mobile devices, and thus failing to provide an ideal solution. Therefore, existing technologies present an irreconcilable contradiction between meeting high torque output demands and maintaining lightweight and high-efficiency devices. Utility Model Content

[0005] The purpose of this invention is to provide an external rotor brushless DC hub motor that can effectively increase output torque while maintaining the lightweight design of the device, in order to overcome the shortcomings of the above-mentioned technical problems.

[0006] To achieve the above objectives, this utility model provides an external rotor brushless DC hub motor, which includes:

[0007] A stator mechanism, the stator mechanism including a fixed frame and a first coupler disposed on the fixed frame;

[0008] A moving mechanism, the moving mechanism including a rotating ring and a second coupler disposed on the inner wall of the rotating ring, and a base plate disposed at one end of the rotating ring;

[0009] Driven by direct current, based on the electromagnetic interaction between the first coupler and the second coupler in a non-contact manner, a rotational torque is generated on the rotating ring, so that the rotating ring rotates around the stator mechanism;

[0010] A rotating shaft, one end of which is connected to the base plate via a planetary gear mechanism, and the other end of which is used to drive the load to rotate.

[0011] Preferably, the first coupler includes a plurality of electromagnetic coils arranged in a ring at intervals, and the second coupler includes a plurality of magnetic sheets arranged in a ring at intervals; under the action of direct current, the electromagnetic coils are activated in a preset phase sequence to form electromagnetic poles that are spatially alternately distributed, so as to generate a rotating magnetic field covering the moving part mechanism, which provides the rotational torque to the rotating ring.

[0012] Preferably, the mounting bracket is further provided with a circuit board, on which a plurality of Hall effect sensors are provided at different positions. The Hall effect sensors are used to detect changes in the magnetic field on the magnetic sheet at the corresponding position to obtain position information of the corresponding magnetic sheet. The position information is used to control the electronic commutation of the current in the electromagnetic coil.

[0013] Preferably, the planetary gear mechanism includes a sun gear and three planet gears meshing with the sun gear. The sun gear is disposed on the side of the base plate facing away from the interior of the rotating ring. A gear ring is also disposed below the base plate. The three planet gears mesh with the gear ring and are mounted on a gear carrier. A through hole is also provided on the base plate. One end of the rotating shaft passes through the through hole and is connected to the sun gear. The rotating ring drives the rotating shaft to rotate by means of the sun gear.

[0014] Preferably, the bottom of the gear ring is further provided with a rear end cover, and a first bearing is embedded in the center of the rear end cover. One end of the rotating shaft passes through the sun gear and is rotatably connected to the first bearing.

[0015] Preferably, it also includes a housing disposed around the outer periphery of the rotating ring, one end of which is connected to the edge of the rear end cover.

[0016] Preferably, the other end of the housing is also provided with a front end cover that closes the stator mechanism and the rotor mechanism.

[0017] Preferably, a second bearing is also embedded in the center of the front end cover, and the other end of the rotating shaft extends out of the front end cover and is rotatably connected to the second bearing.

[0018] Compared with existing technologies, the hub motor provided by the above technical solution integrates a planetary gear mechanism between the base plate of the rotating ring of the mover mechanism and the output rotating shaft. This planetary gear mechanism can effectively change the speed and increase the torque generated by the rotating ring, converting the small torque generated by the motor at a higher speed into a larger torque and lower speed suitable for driving the load through speed reduction and torque increase, thereby ensuring that the motor can meet the driving requirements of the load while operating efficiently. It can be seen that the above hub motor has the advantages of compact structure, high transmission efficiency and large output torque. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the hub motor in an embodiment of this utility model.

[0020] Figure 2 for Figure 1 Exploded view of the in-wheel hub motor.

[0021] Figure 3 for Figure 1 Longitudinal cross-sectional view of the in-wheel hub motor.

[0022] Figure 4 This is a diagram showing the internal structure of the hub motor in an embodiment of this utility model.

[0023] Figure 5 This is a frontal structural diagram of the rotating ring in an embodiment of this utility model.

[0024] Figure 6 This is a back view structural diagram of the rotating ring in an embodiment of this utility model.

[0025] Figure 7 Planetary gear mechanism in the embodiments of this utility model Detailed Implementation

[0026] To explain in detail the technical content, structural features, objectives and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0027] This embodiment discloses an external rotor brushless DC hub motor, such as Figures 1 to 7 It includes a stator mechanism, a mover mechanism, and a rotating shaft 3.

[0028] The stator mechanism includes a fixed frame 10 and a first coupler 11 disposed on the fixed frame 10.

[0029] The moving mechanism includes a rotating ring 20 and a second coupler 21 disposed on the inner wall of the rotating ring 20. A base plate 22 is disposed at one end of the rotating ring 20.

[0030] Driven by direct current, based on the electromagnetic interaction between the first coupler 11 and the second coupler 21 in a non-contact manner, a rotational torque is generated on the rotating ring 20, so that the rotating ring 20 rotates around the stator mechanism.

[0031] One end of the rotating shaft 3 is connected to the base plate 22 via a planetary gear mechanism 4, and the other end of the rotating shaft 3 is used to drive the load to rotate.

[0032] In this embodiment, the first coupler 11 on the stator mechanism and the second coupler 21 on the mover mechanism generate a non-contact electromagnetic interaction under the drive of a direct current. This interaction generates a rotational torque on the rotating ring 20, driving the rotating ring 20 to rotate around the stator mechanism. The rotational motion of the rotating ring 20 is transmitted to the planetary gear mechanism 4 through the base plate 22 provided at one end of it.

[0033] The planetary gear mechanism 4, as the core speed reduction and torque amplification unit, transforms the high-speed, low-torque rotational motion generated by the rotating ring 20 into a low-speed, high-torque output, which is then transmitted to the rotating shaft 3, which drives the external load.

[0034] Therefore, based on the above-described hub motor structure, firstly, the planetary gear mechanism 4 effectively amplifies torque through multi-stage transmission, converting the motor's output speed into low-speed, high-torque operation. The reduction ratio is positively correlated with the torque amplification factor. This allows the motor to output several times the torque of traditional direct-drive methods under the same input power, effectively solving the problems of insufficient torque causing jamming, slippage, and even stalling in existing hub motors under high-load scenarios such as climbing slopes greater than 60 degrees. This significantly enhances the equipment's climbing and obstacle-crossing capabilities.

[0035] Secondly, this integrated design avoids the drawbacks of increasing motor size or input current in order to increase torque in traditional solutions, thus avoiding a significant increase in motor weight and energy consumption, which meets the design requirements of lightweight and high-efficiency mobile devices.

[0036] Furthermore, through the speed reduction effect of the planetary gear mechanism 4, the motor can operate at a higher speed range when outputting the same torque. This helps to improve the working efficiency of the motor and reduce the temperature rise of the motor body, thereby extending the service life of the motor and improving its operational stability.

[0037] Overall, this embodiment significantly improves the torque output capability and environmental adaptability of the hub motor without sacrificing the motor's compactness, providing a reliable drive solution for the stable and efficient operation of fully automated intelligent equipment in complex terrain.

[0038] On the other hand, the first coupler 11 includes a plurality of electromagnetic coils 11 arranged in a ring at intervals. The second coupler 21 includes a plurality of magnetic plates 21 arranged in a ring at intervals. Under the action of direct current, the electromagnetic coils 11 are activated in a preset phase sequence to form electromagnetic poles that are spatially alternately distributed, thereby generating a rotating magnetic field covering the moving mechanism, which provides rotational torque to the rotating ring 20.

[0039] In this embodiment, when a direct current is sequentially applied to each electromagnetic coil 11 according to a preset phase sequence, each electromagnetic coil 11 will generate a corresponding magnetic pole (north or south pole) according to the direction of the current. By precisely controlling the on / off state and direction of the current, these electromagnetic coils 11 can work together to form an array of electromagnetic poles that are alternately distributed in space.

[0040] Due to the phase sequence activation of the current, this electromagnetic pole array manifests as a rotating magnetic field in space. This rotating magnetic field interacts with the magnetic plate 21. According to the principle that like poles repel and unlike poles attract, the rotating magnetic field "drags" the magnetic plate 21 (and the rotating coil 20 it is in) to follow its rotation direction, thereby providing a continuous torque to the rotating coil 20. This design ensures that the motor can smoothly and efficiently convert electrical energy into mechanical energy, providing a stable input for subsequent torque amplification.

[0041] For the mover and stator mechanisms described above, firstly, the combination of electromagnetic coil 11 and magnetic sheet 21 enables the motor to precisely control the generation and rotation of the magnetic field, thereby achieving precise control of the rotational torque. By adjusting the activation sequence and current magnitude of the electromagnetic coil 11, the motor speed and output torque can be flexibly adjusted, improving the motor's controllability and adaptability.

[0042] Secondly, this non-contact electromagnetic coupling method reduces mechanical friction and wear, lowers energy loss, improves motor operating efficiency and reliability, and extends motor lifespan. Because it avoids physical contact, it also reduces operating noise.

[0043] Furthermore, by activating the electromagnetic coil 11 with a preset phase sequence to form a rotating magnetic field, the rotating coil 20 can smoothly and continuously obtain torque, avoiding the sparking, wear, and maintenance problems caused by commutators and brushes in traditional brushed motors. This results in a more compact and maintenance-free motor structure. This design also supports stable operation of the motor over a wide speed range, providing a solid foundation for the application of hub motors in various complex terrains.

[0044] It should be noted that the magnetic sheet 21 can be made of different types of permanent magnet materials, such as neodymium iron boron magnets (which provide high magnetic energy product and are suitable for high torque output) or ferrite magnets (which are lower in cost and suitable for general applications), or soft magnetic materials can be used in combination with electromagnets to form a reluctance motor structure. The shape and size of the magnetic sheet 21 can also be optimized, for example, by using an arc-shaped magnetic sheet 21 or an irregularly shaped magnetic sheet 21 to improve the magnetic field distribution, reduce harmonic components, and improve motor efficiency.

[0045] In addition to the preset phase sequence, the activation method of electromagnetic coil 11 can also employ other control algorithms, such as field-oriented control (FOC) or direct torque control (DTC), to achieve more precise torque and speed control and improve dynamic response capabilities. Furthermore, to further optimize performance, the core material of electromagnetic coil 11 can be improved by selecting low-loss silicon steel sheets or amorphous alloy materials to reduce eddy current losses and hysteresis losses, thereby improving motor efficiency.

[0046] Furthermore, a circuit board 5 is also provided on the mounting bracket 10. Several Hall effect sensors are provided on the circuit board 5, which are located at different positions. The Hall effect sensors are used to detect changes in the magnetic field on the corresponding magnetic sheet 21 to obtain the position information of the corresponding magnetic sheet 21. The position information is used to control the electronic commutation of the current in the electromagnetic coil 11.

[0047] This embodiment provides accurate feedback information for the electronic commutation of the electromagnetic coil 11 by detecting the position of the magnetic sheet 21 in real time.

[0048] Specifically, circuit board 5 is mounted on the fixed frame 10 of the stator mechanism, serving as the core processing unit for motor control. Several Hall effect sensors are arranged on circuit board 5, positioned at different angular locations corresponding to the rotation path of the magnetic plate 21. When the rotating ring 20 of the mover mechanism rotates, the magnetic plate 21 on its inner wall passes sequentially through these Hall effect sensors. Each Hall effect sensor outputs a corresponding electrical signal when it senses a change in the magnetic field of the magnetic plate 21 (e.g., a switch from the south pole to the north pole or a change in magnetic field strength).

[0049] By analyzing the signal combinations and timing from different Hall effect sensors, the control logic on circuit board 5 can accurately determine the real-time position information of the current magnetic plate 21, i.e., the precise angular position of the rotor. This real-time position information is quickly fed back to the electronic commutation control module.

[0050] Based on this location information, the control module precisely determines when and how to switch the DC current supplied to the electromagnetic coil 11 to ensure that the direction of the magnetic field generated by the stator always maintains the optimal interaction angle with the direction of the magnetic field of the rotor magnetic plate 21, thereby generating maximum and continuous torque. This closed-loop control mechanism ensures that the motor can achieve efficient, smooth and rapid operation under various operating conditions.

[0051] On the other hand, the planetary gear mechanism 4 includes a sun gear 40 and three planet gears 41 meshing with the sun gear 40. The sun gear 40 is located on the side of the base plate 22 facing away from the interior of the rotating ring 20. A gear ring 42 is also provided below the base plate 22. The three planet gears 41 mesh with the gear ring 42 and are mounted on a gear carrier 43. The base plate 22 also has a through hole 23. One end of the rotating shaft 3 passes through the through hole 23 and is connected to the sun gear 40. The rotating ring 20 drives the rotating shaft 3 to rotate by means of the sun gear 40.

[0052] In addition, a cover plate 44 is provided inside the gear ring 42 to cover the planetary gears.

[0053] The rotational motion of the rotating ring 20 is transmitted to the planetary gear mechanism 4 through the base plate 22. After a series of gear meshing and motion conversion, it is finally output to the rotating shaft 3 in the form of high torque and low speed.

[0054] Specifically, the sun gear 40 is located at the center of the planetary gear mechanism 4 and is tightly connected to one end of the rotating shaft 3 through the through hole 23 on the base plate 22, becoming the output end of the planetary gear mechanism 4. Three planet gears 41 are evenly distributed around the sun gear 40 and mesh with both the sun gear 40 and the ring gear 42.

[0055] These planetary gears 41 are mounted on a gear carrier 43, which ensures that the planetary gears 41 can rotate on their own axis while also revolving around the sun gear 40.

[0056] When the rotating ring 20 (and the gear ring 42 fixed to it) rotates, the gear ring 42 drives the planetary gears 41 that mesh with it. Since the planetary gears 41 simultaneously mesh with the sun gear 40 and are constrained by the gear carrier 43, this double meshing and constraint causes the planetary gears 41 to rotate on their own axis while the gear carrier 43 also drives them to revolve around the sun gear 40. Ultimately, this combination of motion results in the sun gear 40 rotating at a much lower speed than the gear ring 42, but with a significantly amplified output torque. The rotating shaft 3 is directly connected to the sun gear 40, thus enabling the rotating ring 20 to drive the rotating shaft 3 to rotate via the planetary gear mechanism 4, providing high torque output.

[0057] In this embodiment, the tooth ratio of the sun gear 40, planet gears 41, and ring gear 42 can be adjusted to achieve different reduction ratios, thereby meeting the customized requirements of speed and torque for different application scenarios. The number of planet gears 41 can be increased or decreased according to actual load requirements and space constraints. For example, in extremely high load applications, it can be considered to increase to four sets of planet gears 41 to further distribute the load.

[0058] On the other hand, a rear end cover 60 is provided at the bottom of the gear ring 42. A first bearing 61 is embedded in the center of the rear end cover 60. One end of the rotating shaft 3 passes through the sun gear 40 and is rotatably connected to the first bearing 61.

[0059] The main function of the rear end cover 60 is to provide a closed cavity for the planetary gear mechanism 4 to prevent external contaminants such as dust and moisture from entering, while also providing a structural foundation for supporting the rotating shaft 3. A first bearing 61 is embedded in the center of the rear end cover 60, with its inner ring tightly fitted to the rotating shaft 3, and its outer ring fixed in the bearing seat of the rear end cover 60 by press fitting or snap rings.

[0060] After one end of the rotating shaft 3 passes through the base plate 22 and connects to the sun gear 40, its extension extends out from the other side of the sun gear 40 and rotatably connects to the first bearing 61 at the center of the rear end cover 60. Thus, the rotating shaft 3 obtains a stable support point at the output end of the planetary gear mechanism 4, ensuring its stability and concentricity during high-speed rotation and torque transmission. This bearing configuration effectively absorbs the radial and axial loads generated by the rotating shaft 3 during operation, significantly reducing frictional losses and ensuring precise meshing and long-life operation of the planetary gear mechanism 4.

[0061] On the other hand, the hub electrode also includes a housing 7 disposed around the rotating ring 20, one end of which is connected to the edge of the rear end cover 60. This housing 7 provides comprehensive physical protection for the internal components of the hub motor.

[0062] The connection between the housing 7 and the rear end cover 60 can be varied. In addition to bolt connection, welding (providing stronger sealing), snap-fit ​​connection (facilitating quick assembly and disassembly), or threaded connection can also be used. To further improve the protection level, sealing rings (such as O-rings or rubber gaskets) or sealant can be added at the connection between the housing 7 and the rear end cover 60 to achieve a higher IP protection level (such as IP67), making it completely dustproof and waterproof.

[0063] On the other hand, the other end of the housing 7 is also provided with a front cover 80 that closes the stator mechanism and the mover mechanism.

[0064] In this embodiment, by providing a front cover 80 at the other end of the housing 7, a complete enclosure and high-level protection for the external rotor brushless DC hub motor are achieved. Specifically, the addition of the front cover 80, together with the housing 7 and the rear cover 60, forms a completely sealed cavity, effectively isolating external contaminants such as dust, moisture, chemicals, and oil from corroding the stator and rotor mechanisms. This allows the motor to operate stably and reliably in extremely harsh outdoor, industrial, or humid environments, greatly extending its service life.

[0065] On the other hand, a second bearing 81 is also embedded in the center of the front cover 80, and the other end of the rotating shaft 3 passes through the front cover 80 and is rotatably connected to the second bearing 81.

[0066] In this embodiment, the second bearing 81 and the first bearing 61 (in the rear end cover 60) typically form a bearing pair to jointly support the rotating shaft 3. After passing through the planetary gear mechanism 4 and being supported by the first bearing 61, the "other end" of the rotating shaft 3 (i.e., the output end of the motor) continues to extend out of the front end cover 80. This portion extending out of the front end cover 80 is the output shaft used to connect to the external load. The inner ring of the second bearing 81 fits tightly with this output end of the rotating shaft 3, while the outer ring is fixed in the bearing housing of the front end cover 80.

[0067] During motor operation, the rotating shaft 3 transmits torque while also bearing loads from external loads (such as radial and axial forces from the wheels) and unbalanced forces within the motor. The second bearing 81 effectively absorbs and disperses these radial and axial loads, ensuring that the rotating shaft 3 maintains precise concentricity and stability under high-speed rotation and high-load conditions, minimizing shaft deflection and vibration.

[0068] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Therefore, any equivalent variations made in accordance with the scope of the present utility model application shall still fall within the scope of the present utility model.

Claims

1. An external rotor brushless DC hub motor, characterized in that, include: A stator mechanism, the stator mechanism including a fixed frame and a first coupler disposed on the fixed frame; A moving mechanism, the moving mechanism including a rotating ring and a second coupler disposed on the inner wall of the rotating ring, and a base plate disposed at one end of the rotating ring; Driven by direct current, based on the electromagnetic interaction between the first coupler and the second coupler in a non-contact manner, a rotational torque is generated on the rotating ring, so that the rotating ring rotates around the stator mechanism; A rotating shaft, one end of which is connected to the base plate via a planetary gear mechanism, and the other end of which is used to drive the load to rotate.

2. The external rotor brushless DC hub motor according to claim 1, characterized in that, The first coupler includes a plurality of electromagnetic coils arranged in a ring at intervals, and the second coupler includes a plurality of magnetic sheets arranged in a ring at intervals. Under the action of direct current, the electromagnetic coils are activated in a preset phase sequence to form electromagnetic poles that are spatially alternately distributed, thereby generating a rotating magnetic field covering the moving part mechanism. This rotating magnetic field provides the rotational torque to the rotating ring.

3. The external rotor brushless DC hub motor according to claim 2, characterized in that, The mounting bracket is also equipped with a circuit board, on which are mounted a plurality of Hall effect sensors located at different positions. The Hall effect sensors are used to detect changes in the magnetic field on the corresponding magnetic sheet to obtain position information of the corresponding magnetic sheet. The position information is used to control the electronic commutation of the current in the electromagnetic coil.

4. The external rotor brushless DC hub motor according to claim 1, characterized in that, The planetary gear mechanism includes a sun gear and three planet gears meshing with the sun gear. The sun gear is located on the side of the base plate facing away from the inside of the rotating ring. A gear ring is also provided below the base plate. The three planet gears mesh with the gear ring and are mounted on a gear carrier. A through hole is also provided on the base plate. One end of the rotating shaft passes through the through hole and is connected to the sun gear. The rotating ring drives the rotating shaft to rotate by means of the sun gear.

5. The external rotor brushless DC hub motor according to claim 4, characterized in that, The bottom of the gear ring is also provided with a rear end cover, and a first bearing is embedded in the center of the rear end cover. One end of the rotating shaft passes through the sun gear and is rotatably connected to the first bearing.

6. The external rotor brushless DC hub motor according to claim 5, characterized in that, It also includes a housing located around the rotating ring, one end of which is connected to the edge of the rear end cover.

7. The external rotor brushless DC hub motor according to claim 6, characterized in that, The other end of the housing is also provided with a front cover that closes the stator mechanism and the mover mechanism.

8. The external rotor brushless DC hub motor according to claim 7, characterized in that, A second bearing is also embedded in the center of the front cover, and the other end of the rotating shaft passes through the front cover and is rotatably connected to the second bearing.

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