Birotor brushless motor

Abstract

The invention relates to the technical field of motors, and discloses a double-rotor brushless motor, which comprises an outer rotor, an inner rotor, a stator core and a first PCB, the stator core comprises a yoke part, a plurality of outer tooth parts and a plurality of inner tooth parts, the yoke part is of a hollow cylindrical structure, the plurality of outer tooth parts are arranged on the outer peripheral side of the yoke part at equal intervals, and the inner tooth parts are arranged on the outer peripheral side of the yoke part at equal intervals. The outer rotor is sleeved on the outer side of the outer tooth part, the plurality of inner tooth parts are arranged on the inner circumferential side of the yoke part at equal intervals, the inner rotor is sleeved by the inner tooth parts, at least one end of each inner tooth part retracts relative to the axial end part of the yoke part in the axial direction of the yoke part, and at least one end of each inner tooth part retracts relative to the axial end part of the yoke part in the axial direction of the yoke part. The first PCB is arranged at one end, which is axially retracted relative to the yoke part, of the inner tooth part, and the first PCB is positioned on the inner side of the yoke part. According to the invention, the influence of the installation of the PCB for controlling the rotation of the inner rotor on the reduction of the size of the motor can be relieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric machines, in particular to a double-rotor brushless electric machine. BACKGROUND

[0002] With the development of electric machine technology, the demand for electric machines in the market is becoming more and more diversified. For example, for electric machines applied to sweeping robots, a double-rotor brushless electric machine is often used to control the sweeper.

[0003] For a double-rotor brushless electric machine, two rotors share one stator. If the PCBs (Printed Circuit Boards) of the two rotors are integrated into one PCB, the design difficulty of the PCB will be greatly increased.

[0004] At present, each rotor of the existing double-rotor brushless electric machine is often configured with a PCB. In order to avoid electromagnetic interference and wire interference between the two PCBs, the two PCBs are often arranged at the two axial ends of the electric machine. For example, the PCB is installed on the axial end cover of the electric machine.

[0005] For the related technology in the above, the inventor believes that this arrangement scheme will increase the axial length of the electric machine, and there is a defect of affecting the size reduction of the electric machine. SUMMARY

[0006] In order to alleviate the problem of affecting the size reduction of the electric machine, the present application provides a double-rotor brushless electric machine.

[0007] The double-rotor brushless electric machine provided by the present application adopts the following technical scheme: A double-rotor brushless electric machine, comprising an outer rotor, an inner rotor, a stator core, and a first PCB, the stator core comprises a yoke, a plurality of outer tooth portions, and a plurality of inner tooth portions, the yoke is a hollow cylindrical structure, a plurality of the outer tooth portions are arranged at equal intervals on the outer circumferential side of the yoke, the outer rotor is sleeved on the outer side of the outer tooth portion, a plurality of the inner tooth portions are arranged at equal intervals on the inner circumferential side of the yoke, the inner rotor is sleeved by the inner tooth portion, in the axial direction of the yoke, at least one end of the inner tooth portion is recessed relative to the axial end portion of the yoke, the first PCB is arranged at the end of the inner tooth portion that is recessed relative to the yoke in the axial direction, and the first PCB is located on the inner side of the yoke.

[0008] By adopting the above technical solution, the outer teeth of the first coil used for winding and driving the outer rotor to rotate are set on the outer periphery of the yoke, and the inner teeth of the second coil used for winding and driving the inner rotor to rotate are set on the inner periphery of the yoke. In the axial direction of the yoke, one end of the inner teeth is recessed relative to the axial end of the yoke, thereby forming a receiving space for mounting the first PCB. The first PCB used for controlling the rotation of the inner rotor is mounted on the inner side of the yoke, thereby reducing the axial length of the motor and mitigating the impact of mounting the first PCB on the reduction of motor size.

[0009] Optionally, a plurality of fasteners are provided on the inner circumferential surface of the yoke, the fasteners being located at the end of the internal tooth portion that is axially recessed relative to the yoke portion, and the first PCB is detachably connected to the fasteners.

[0010] By adopting the above technical solution, the first PCB is securely connected to the inner circumference of the yoke of the stator core using fasteners, preventing the first PCB from shifting or loosening due to vibration or force during motor operation, ensuring the stability and reliability of the electrical connection. The detachable connection method makes the assembly, replacement or maintenance of the first PCB more convenient, improving production efficiency and maintenance convenience, and reducing later maintenance costs.

[0011] Optionally, the dual-rotor brushless motor includes multiple Hall elements, which are fixedly connected to the inner wall of the yoke and electrically connected to the first PCB. Axially, the Hall elements are located on the side of the first PCB near the inner tooth portion; radially, the Hall elements at least partially overlap with the inner rotor.

[0012] By adopting the above technical solution, the Hall element is installed on the stator core, and the Hall element is set separately from the first PCB. On the one hand, this avoids electromagnetic interference caused by the traces in the first PCB to the Hall element, and at the same time ensures that the mechanical position of its sensing surface relative to the internal teeth and the inner rotor is absolutely fixed and will not shift due to slight deformation or vibration of the first PCB. For dual-rotor motors, the relative phase control of the inner and outer rotors is crucial, and the stable installation of the Hall element is the foundation for ensuring control accuracy. On the other hand, the position of the Hall element allows it to directly and closely sense the magnetic field changes of the inner rotor magnets, reducing signal attenuation or distortion caused by distance and structural obstruction. This provides the controller with a more accurate and timely feedback signal of the inner rotor position, which helps to improve the control accuracy of the inner rotor.

[0013] Optionally, the yoke, the external teeth, and the internal teeth are integrally formed.

[0014] By adopting the above technical solution, the stator core can be made of SMC (Soft Magnetic Composite), which helps to reduce the iron loss of the stator core and improve the efficiency of the motor.

[0015] Optionally, the stator core includes a plurality of first laminations and a plurality of second laminations. The first laminations include an integrally formed yoke, an external tooth, and an internal tooth. The second laminations include an integrally formed yoke and an external tooth. The plurality of second laminations are stacked on the same side of all the first laminations.

[0016] By adopting the above technical solution, the stator core is formed by stacking multiple first laminations and second laminations. The first lamination includes an integrally formed yoke, an external toothed portion, and an internal toothed portion. The second lamination includes an integrally formed yoke and an external toothed portion. Multiple second laminations are stacked on one side of the first lamination, thereby causing one end of the internal toothed portion to be recessed relative to the axial end of the yoke, forming a receiving space for mounting the first PCB. By controlling the number of second laminations, the size of the receiving space for mounting the first PCB can be controlled. The stator core in this solution can be formed by using two types of laminations, which can reduce the manufacturing cost of the stator core. Moreover, since the yoke, external toothed portion, and internal toothed portion are integrally formed, compared with the solution of manufacturing the toothed portion and yoke separately, the structural strength of the lamination can be guaranteed, which helps to ensure the reliability of motor operation.

[0017] Optionally, the fastener has a threaded hole at one end near the first PCB, and the first PCB has multiple mounting holes for bolts to pass through. The multiple mounting holes are configured one-to-one with the multiple fasteners, and the bolt passes through the mounting hole and is fixedly connected to the fastener through the threaded hole on the fastener.

[0018] By adopting the above technical solution, the axial and radial / circumferential positions of the first PCB can be precisely controlled by the cooperation of bolts, mounting holes and threaded holes. Combined with the circumferentially spaced layout of the fasteners, the mounting flatness and parallelism of the first PCB can be guaranteed. In addition, the bolt connection method facilitates repeated disassembly and assembly of the first PCB, which greatly facilitates production debugging, maintenance and replacement and later upgrades.

[0019] Optionally, when the internal tooth portion is provided on the radial side of the external tooth portion, the lines of symmetry of the external tooth portion and the internal tooth portion are collinear in the radial direction.

[0020] By adopting the above technical solution, when the symmetry lines of the inner and outer teeth are radially collinear, it means that each "outer tooth-yoke-inner tooth" unit geometrically forms a magnetic circuit branch symmetrical about the radial line. When the motor is in operation, the magnetic flux emitted from the coil wound around the inner tooth can be guided relatively directly along the yoke to the corresponding inner tooth, forming a magnetic circuit serving the inner rotor, and vice versa. This layout makes the spatial coupling of the inner and outer magnetic circuits clear, the path well-defined, and symmetrical. The symmetrical collinear layout ensures that the magnetic flux paths between adjacent inner and outer teeth are geometrically separated as much as possible. This helps reduce unnecessary coupling (cross-coupling) generated by the magnetic fields of the inner and outer rotors through the stator core. This makes the internal control of the motor (such as independent or coordinated control of the inner and outer rotors) more precise, avoiding increased torque ripple or complicated control characteristics caused by mutual interference of magnetic circuits.

[0021] Optionally, in the first operating mode, the radially adjacent outer teeth and inner teeth are either both N-pole or both S-pole.

[0022] By adopting the above technical solution, the first working mode is when the inner rotor and the outer rotor work simultaneously. The adjacent outer teeth and inner teeth along the radial direction are both N poles or both S poles, which can avoid magnetic line interference between the inner stator and the outer stator and ensure the stability of the operation of the inner rotor and the outer rotor.

[0023] Optionally, in the second operating mode, one of the radially adjacent external teeth and internal teeth is an N pole and the other is an S pole.

[0024] By adopting the above technical solution, the second working mode is when only one of the inner rotor and the outer rotor is working. In the radially adjacent outer and inner teeth, one is the N pole and the other is the S pole, which can enhance the torque of the outer rotor or the inner rotor. The switching of the N pole and S pole of the teeth can be controlled by controlling the current direction of the coil wound on it.

[0025] Optionally, a second PCB is provided on the axial end cover of the motor. The second PCB is used to control the rotation of the outer rotor. The second PCB integrates a Hall element for detecting information of the outer rotor, and the axial end cover is located on the side of the stator core on which the first PCB is installed.

[0026] By adopting the above technical solution, the two PCBs are located on the same side, which facilitates wiring and helps to reduce the axial dimension of the motor.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. By setting the outer teeth of the first coil used for winding and driving the outer rotor to rotate on the outer periphery of the yoke, and setting the inner teeth of the second coil used for winding and driving the inner rotor to rotate on the inner periphery of the yoke, one end of the inner teeth is recessed relative to the axial end of the yoke in the axial direction, thereby forming a receiving space for mounting the first PCB. The first PCB used for controlling the rotation of the inner rotor is mounted on the inner side of the yoke, thereby reducing the axial length of the motor and mitigating the impact of mounting the first PCB on the reduction of motor size. 2. By mounting the Hall element on the stator core and separating it from the first PCB, electromagnetic interference caused by the traces in the first PCB to the Hall element can be avoided. At the same time, it ensures that the mechanical position of its sensing surface relative to the internal teeth and the inner rotor is absolutely fixed and will not shift due to slight deformation or vibration of the first PCB. For dual rotor motors, the relative phase control of the inner and outer rotors is crucial, and the stable mounting of the Hall element is the basis for ensuring control accuracy. 3. By integrally molding the fastener and the yoke, the first PCB is tightly connected to the metal stator core through the fastener, which can form an additional heat conduction path. This helps to transfer the heat generated by the electronic components on the first PCB to the stator core, improves heat dissipation conditions, and enhances motor reliability. In addition, the integral molding of the fastener and the yoke simplifies the assembly process of the first PCB, reduces assembly steps and the number of parts, and is conducive to mass production. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application; Figure 2 This is a cross-sectional view of the stator core portion in an embodiment of this application; Figure 3 This is a schematic diagram of the stator core portion in an embodiment of this application; Figure 4 This is a structural schematic diagram of the fastener in the embodiments of this application.

[0029] Reference numerals: 1. Stator core; 10. Yoke; 11. External gear; 12. Internal gear; 13. Fixing member; 2. First PCB; 3. Hall element. Detailed Implementation

[0030] To more clearly illustrate the overall concept of this application, the following is in conjunction with the appendix. Figures 1-4 This application will be described in further detail.

[0031] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaustively describe all possible methods of this application, nor to limit the scope of this application.

[0032] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that, unless otherwise specified, the following embodiments can be referred to, borrowed from or combined with each other, and the same terms, similar features and similar implementation steps in different embodiments will not be described again. Unless otherwise specified, the radial, circumferential and axial directions referred to below refer to the radial, circumferential and axial directions of the stator core.

[0033] This application discloses a dual-rotor brushless motor. (Refer to...) Figure 1 and Figure 2 A dual-rotor brushless motor includes an outer rotor, an inner rotor, a stator core 1, a first PCB 2, and a second PCB.

[0034] The stator core 1 includes a yoke 10, multiple external toothed sections 11, and multiple internal toothed sections 12, all integrally formed. The yoke 10 is a hollow cylindrical structure, and its cross-section perpendicular to its axial direction is annular. Multiple external toothed sections 11 are evenly spaced on the outer periphery of the yoke 10, and are used to wind a first coil that drives the outer rotor to rotate. The outer rotor is fitted onto the outside of the external toothed sections 11. Multiple internal toothed sections 12 are evenly spaced on the inner periphery of the yoke 10, and are used to wind a second coil that drives the inner rotor to rotate. The inner rotor is fitted onto the inner toothed sections 12.

[0035] Along the axial direction of the yoke 10, both ends of the external toothed portion 11 are flush with the two axial ends of the yoke 10. One end of the internal toothed portion 12 is flush with one axial end of the yoke 10. The length of the internal toothed portion 12 is less than that of the yoke 10, thereby causing the other end of the internal toothed portion 12 to be recessed relative to the other axial end of the yoke 10, thus forming a receiving space for mounting the first PCB2. The first PCB2 is mounted on the recessed end of the internal toothed portion 12 relative to the yoke 10. The first PCB2 is located inside the yoke 10, thereby reducing the axial length of the motor and mitigating the impact of mounting the first PCB2 on the reduction of motor size.

[0036] In a preferred embodiment, the stator core 1 includes a plurality of first laminations and a plurality of second laminations. The first laminations include an integrally formed yoke 10, an external toothed portion 11, and an internal toothed portion 12. The second laminations include an integrally formed yoke 10 and an external toothed portion 11. The plurality of second laminations are stacked on the same side of all the first laminations. The stator core 1 is formed by stacking a plurality of first laminations and second laminations. By stacking a plurality of second laminations on one side of the first laminations, one end of the internal toothed portion 12 is recessed relative to the axial end of the yoke 10, forming a receiving space for mounting the first PCB 2. By controlling the number of second laminations, the size of the receiving space for mounting the first PCB 2 can be controlled.

[0037] Reference Figure 2 and Figure 3 Multiple fasteners 13 are provided on the inner circumferential surface of the yoke 10. The fasteners 13 are located at the end of the internal toothed portion 12 that is axially recessed relative to the yoke 10, and are detachably connected to the first PCB2. By using the fasteners 13 to securely connect the first PCB2 to the inner circumferential surface of the yoke 10 of the stator core 1, displacement or loosening of the first PCB2 due to vibration or force during motor operation is prevented, ensuring the stability and reliability of the electrical connection. The detachable connection method makes the assembly, replacement, or maintenance of the first PCB2 more convenient, improving production efficiency and maintenance convenience, and reducing subsequent maintenance costs.

[0038] The fastener 13 is integrally formed with the yoke 10. The first PCB2 is tightly connected to the metal stator core 1 through the fastener 13, forming an additional heat conduction path. This helps to transfer the heat generated by the electronic components on the first PCB2 to the stator core 1, improving heat dissipation and increasing motor reliability. In addition, the integral formation of the fastener 13 and the yoke 10 simplifies the assembly process of the first PCB2, reduces assembly steps and the number of parts, and is beneficial for mass production.

[0039] Reference Figure 3 and Figure 4 Multiple fasteners 13 are evenly spaced along the circumference of the stator core 1. The first PCB2 is usually a ring-shaped or plate-shaped structure with ring-shaped features. The evenly distributed fasteners provide uniform support and can effectively prevent the first PCB2 from warping due to its own weight, assembly stress or thermal stress. When the motor vibrates at high speed, this layout can evenly distribute the vibration load to all fasteners and avoid fatigue damage to the first PCB2 caused by stress concentration.

[0040] In a preferred embodiment, the fastener 13 has a threaded hole at one end near the first PCB2, and the first PCB2 has multiple mounting holes for bolts. The mounting holes correspond to multiple fasteners 13, and the bolts pass through the mounting holes and are then fixedly connected to the fasteners 13 via the threaded holes. By utilizing the cooperation of bolts, mounting holes, and threaded holes, the axial and radial / circumferential positions of the first PCB2 can be precisely controlled. Combined with the circumferentially spaced fasteners 13, the mounting flatness and parallelism of the first PCB2 can be guaranteed. Furthermore, the bolted connection facilitates repeated assembly and disassembly of the first PCB2, greatly simplifying production debugging, maintenance, replacement, and future upgrades.

[0041] Reference Figure 3 and Figure 4 The dual-rotor brushless motor includes multiple Hall elements 3, which are fixedly connected to the inner wall of the yoke 10. The Hall elements 3 are electrically connected to the first PCB 2. The Hall elements 3 connected to the inner wall of the yoke 10 are used to detect information from the inner rotor. Axially, the Hall elements 3 are located on the side of the first PCB 2 near the inner tooth 12; radially, the Hall elements 3 at least partially overlap with the inner rotor. By mounting the Hall element 3 on the stator core 1 and separating it from the first PCB 2, electromagnetic interference caused by the traces in the first PCB 2 to the Hall element 3 can be avoided. At the same time, it ensures that the mechanical position of its sensing surface relative to the inner tooth 12 and the inner rotor is absolutely fixed and will not shift due to slight deformation or vibration of the first PCB 2. For a dual-rotor motor, the relative phase control of the inner and outer rotors is crucial, and the stable mounting of the Hall element 3 is the foundation for ensuring control accuracy. On the other hand, the mounting position of the Hall element 3 allows it to directly and closely sense the magnetic field changes of the inner rotor magnets, reducing signal attenuation or distortion caused by distance and structural obstruction. This provides the controller with a more accurate and timely feedback signal of the inner rotor position, which helps to improve the control accuracy of the inner rotor.

[0042] Reference Figure 3When an inner tooth 12 is provided on the radial side of the outer tooth 11, the lines of symmetry of the outer tooth 11 and the inner tooth 12 are collinear in the radial direction. When the lines of symmetry of the inner and outer teeth are collinear in the radial direction, it means that each "outer tooth-yoke-inner tooth" unit geometrically forms a magnetic circuit branch that is symmetrical about the radial line. When the motor is in operation, the magnetic flux emitted from the coil wound around the inner tooth can be guided relatively directly along the yoke to the corresponding inner tooth, forming a magnetic circuit serving the inner rotor, and vice versa. This layout makes the inner and outer magnetic circuits spatially clearly coupled, with well-defined and symmetrical paths. The symmetrical collinear layout makes the magnetic flux paths between adjacent inner and outer teeth as geometrically separated as possible. This helps to reduce the unnecessary coupling (cross coupling) generated by the magnetic fields of the inner and outer rotors through the stator core 1. This makes the internal control of the motor (such as independent or coordinated control of the inner and outer rotors) more precise, avoiding the increase in torque ripple or the complexity of control characteristics caused by mutual interference of magnetic circuits.

[0043] In this embodiment, the first working mode is when the inner rotor and the outer rotor work simultaneously, and the second working mode is when only one of the inner rotor and the outer rotor works.

[0044] In the first operating mode, the radially adjacent outer tooth 11 and inner tooth 12 are both N poles or both S poles, which can avoid magnetic interference between the inner stator and the outer stator and ensure the stability of the operation of the inner rotor and the outer rotor.

[0045] In the second working mode, one of the radially adjacent outer tooth 11 and inner tooth 12 is the N pole and the other is the S pole, which can enhance the torque of the outer rotor or the inner rotor. The switching of the N pole and S pole of the tooth can be controlled by controlling the direction of the current of the coil wound on it.

[0046] A second PCB is mounted on the axial end cover of the motor. The second PCB is used to control the rotation of the outer rotor. The second PCB integrates a Hall element 3 for detecting information about the outer rotor, and the axial end cover is located on the side of the stator core 1 where the first PCB 2 is mounted. By placing the two PCBs on the same side, wiring can be facilitated, which helps to reduce the axial dimension of the motor.

[0047] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0048] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A dual-rotor brushless motor, characterized in that: The device includes an outer rotor, an inner rotor, a stator core (1), and a first PCB (2). The stator core (1) includes a yoke (10), a plurality of outer teeth (11), and a plurality of inner teeth (12). The yoke (10) is a hollow cylindrical structure. The plurality of outer teeth (11) are equally spaced on the outer periphery of the yoke (10). The outer rotor is sleeved on the outer side of the outer teeth (11). The plurality of inner teeth (12) are equally spaced on the inner periphery of the yoke (10). The inner rotor is sleeved by the inner teeth (12). In the axial direction of the yoke (10), at least one end of the inner teeth (12) is recessed relative to the axial end of the yoke (10). The first PCB (2) is disposed at the end of the inner teeth (12) that is recessed relative to the axial end of the yoke (10). The first PCB (2) is located on the inner side of the yoke (10).

2. The dual-rotor brushless motor according to claim 1, characterized in that: The inner circumferential surface of the yoke (10) is provided with a plurality of fasteners (13), the fasteners (13) are located at one end of the inner tooth (12) that is axially recessed relative to the yoke (10), and the first PCB (2) is detachably connected to the fasteners (13).

3. A dual-rotor brushless motor according to claim 1, characterized in that: The dual-rotor brushless motor includes multiple Hall elements (3), which are fixedly connected to the inner wall of the yoke (10). The Hall elements (3) are electrically connected to the first PCB (2). Along the axial direction, the Hall elements (3) are located on the side of the first PCB (2) near the inner tooth (12). Along the radial direction, the Hall elements (3) overlap at least partially with the inner rotor.

4. A dual-rotor brushless motor according to claim 1, characterized in that: The yoke (10), the external teeth (11), and the internal teeth (12) are integrally formed.

5. A dual-rotor brushless motor according to claim 1, characterized in that: The stator core (1) includes a plurality of first laminations and a plurality of second laminations. The first laminations include the integrally formed yoke (10), the external toothed portion (11), and the internal toothed portion (12). The second laminations include the integrally formed yoke (10) and the external toothed portion (11). The plurality of second laminations are stacked on the same side of all the first laminations.

6. A dual-rotor brushless motor according to claim 2, characterized in that: The fastener (13) has a threaded hole at one end near the first PCB (2). The first PCB (2) has multiple mounting holes for passing bolts through it. The multiple mounting holes are set one-to-one with the multiple fasteners (13). After the bolt passes through the mounting hole, it is fixedly connected to the fastener (13) through the threaded hole on the fastener (13).

7. A dual-rotor brushless motor according to claim 1, characterized in that: When the inner tooth (12) is provided on the radial side of the outer tooth (11), the lines of symmetry of the outer tooth (11) and the inner tooth (12) are collinear in the radial direction.

8. A dual-rotor brushless motor according to claim 7, characterized in that: In the first working mode, the outer tooth (11) and the inner tooth (12) that are adjacent in the radial direction are both N poles or both S poles.

9. A dual-rotor brushless motor according to claim 7, characterized in that: In the second operating mode, one of the radially adjacent external teeth (11) and internal teeth (12) is the N pole and the other is the S pole.

10. A dual-rotor brushless motor according to claim 1, characterized in that: The motor has a second PCB on its axial end cover. The second PCB is used to control the rotation of the outer rotor. The second PCB integrates a Hall element (3) for detecting information of the outer rotor. The axial end cover is located on the side of the stator core (1) where the first PCB (2) is installed.

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