A coaxial double-rotor motor and application

Abstract

This invention relates to a coaxial dual-rotor motor and its applications. The stator core is fixed inside a housing and has a central hole, an inner slot, and an outer slot. A crossbeam separates the inner and outer slots. After stator windings are assembled on the stator core, an internal magnetic field and an external magnetic field are constructed. The inner rotor is embedded in the central hole of the stator core and supported by the housing, allowing it to rotate under the influence of the internal magnetic field. The inner rotor has a first output shaft extending from the housing. The outer rotor is sleeved on the outer circumference of the stator core and supported by the housing, allowing it to rotate under the influence of the external magnetic field. The outer rotor has a second output shaft extending from the housing. The second output shaft is hollow and sleeved on the first output shaft, so that the second output shaft and the first output shaft extend coaxially and in the same direction, obtaining dual power output. It can be used to manufacture electric cleaning brushes, beauty instruments, intelligent electric screwdrivers, precision medical bone drills, medical miniature dental taps, miniature gimbal flexible joints, or robotic flexible joints, improving usability and user experience.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a dual-rotor motor. Background Technology

[0002] Currently, to achieve synchronous dual-axis drive, a planetary gear mechanism is usually connected after the motor output, and the dual-axis output is obtained from the planetary gear mechanism. This type of structure is relatively complex, costly, and increases the overall size of the final product. Moreover, the torque of planetary gear transmission is large, which can easily cause output fluctuations. This is used in electric cleaning brushes, smart electric screwdrivers, precision medical bone drills, medical micro-tapping devices, micro gimbal flexible joints, or robot flexible joints, resulting in the product being unstable, prone to displacement, and having a poor user experience. Summary of the Invention

[0003] The purpose of this invention is to provide a coaxial dual-rotor motor that is compact in structure, easy to mass-produce at low cost, and can directly cancel out reaction forces and eliminate torque by utilizing coaxial rotation in physical structure. When used in products, it can effectively improve issues such as vibration, solve the problem of hand-held vibration, and improve usability and user experience.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A coaxial dual-rotor motor, which has the following characteristics: shell, The stator core is fixed inside the outer casing. The stator core has a central hole and inner and outer wire slots distributed sequentially around the central hole. The inner and outer wire slots are separated by a crossbeam. There are multiple inner and outer wire slots, which are arranged in a circle around the center of the central hole. After the stator winding is assembled on the stator core, an internal magnetic field and an external magnetic field are constructed. An inner rotor with a first permanent magnet is embedded in the central hole of the stator core and supported by the outer shell, so that the inner rotor can rotate under the action of the internal magnetic field, and the inner rotor has a first output shaft extending from the outer shell. An outer rotor with a second permanent magnet is sleeved on the outer periphery of the stator core and supported by a housing, so that the outer rotor can rotate under the action of an external magnetic field. The outer rotor has a second output shaft extending from the housing. The second output shaft is hollow and sleeved on the first output shaft, so that the second output shaft and the first output shaft extend out coaxially and in the same direction.

[0005] The above scheme is further described as follows: the outer rotor is a U-shaped body, the first output shaft passes through the interior of the outer rotor, and a first bearing is embedded between the first output shaft and the outer rotor, while a second bearing is embedded between the second output shaft of the outer rotor and the outer casing; the other end of the inner rotor is positioned on the outer casing by a third bearing.

[0006] The above-mentioned solution is further described in that the outer casing has a cylindrical shell and a bottom cover. The cylindrical shell is fixed together with the bottom cover after accommodating the stator core, the inner rotor and the outer rotor. The first output shaft and the second output shaft extend out from the cylindrical shell.

[0007] The above-mentioned solution is further provided that the inner side of the bottom cover has multiple circumferentially distributed support steps, which press against the corresponding ends of the stator core, leaving a gap between the bottom cover and the stator core; the stator core also has an axially penetrating positioning hole, through which a first bolt passes and locks to the bottom cover, fixing the stator core inside the outer casing.

[0008] A further aspect of the above solution is that the bottom cover is in the form of a flange, with an outwardly flared edge on the cylindrical shell, which is connected to the bottom cover by a second bolt.

[0009] A further aspect of the above scheme is that the number of inner and outer slots on the stator core is the same, and the inner and outer slots are arranged one-to-one collinearly in the radial direction of the stator core. In this case, the stator winding is separately set on the crossbeam to construct the inner and outer magnetic fields.

[0010] A further aspect of the above scheme is that the number of inner and outer slots on the stator core is different, and the inner and outer slots are evenly distributed around the center of the central hole. In this case, the stator windings are respectively set on the corresponding slot walls of the inner and outer slots to construct the inner magnetic field and the outer magnetic field.

[0011] The above scheme is further described in that the second output shaft is formed by axial connection of a fixed section and a movable section. The fixed section is integrally formed with the outer rotor, and the movable section is locked to the fixed section by screws. An annular groove is formed on the outer periphery of the connection area between the fixed section and the movable section. The annular groove is adapted to be embedded and assembled with the inner ring of the second bearing.

[0012] To achieve the above objectives, this invention also proposes the application of a coaxial dual-rotor motor in the manufacture of electric cleaning brushes, beauty instruments, intelligent electric screwdrivers, precision medical bone drills, medical miniature dental taps, miniature gimbal flexible joints, or robotic flexible joints.

[0013] This invention designs a motor with one stator and two rotors, achieving direct coaxial dual power output on the motor. When used in manufacturing products, it can be completed independently without the need for an external planetary gear mechanism, resulting in low manufacturing costs and a compact, easy-to-use product. Simultaneously, the coaxial output on the motor directly cancels out reaction forces and eliminates torque, effectively improving vibration and other issues in the product, resolving hand-held vibration problems, and enhancing usability and user experience.

[0014] This invention features a compact structure, is easy to mass-produce at low cost, and is small in size, making it suitable for manufacturing products such as electric cleaning brushes, beauty instruments, intelligent electric screwdrivers, precision medical bone drills, medical miniature dental taps, miniature gimbal flexible joints, or robotic flexible joints. The overall assembly is simple, the operation is stable and reliable, and the service life is long. Attached Figure Description

[0015] Appendix Figure 1 This is a schematic diagram of a preferred embodiment of the present invention; Appendix Figure 2 for Figure 1 Internal structural cross-sectional view of the embodiment; Appendix Figure 3 for Figure 1 Schematic diagram of the structural breakdown of the embodiment; Appendix Figure 4 for Figure 1 A schematic diagram of the stator core assembly structure in the embodiment; Appendix Figure 5 for Figure 1 A schematic diagram of the stator core structure in the embodiment; Appendix Figure 6 for Figure 1 A schematic diagram of the assembly of the outer rotor and stator core in the embodiment; Appendix Figure 7 for Figure 1 A schematic diagram of the external rotor structure in the embodiment; Appendix Figure 8 This is a schematic diagram of one design embodiment of the stator winding of the present invention; Appendix Figure 9 This is a schematic diagram of a second design embodiment of the stator winding of the present invention. Detailed Implementation

[0016] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention.

[0017] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] See Figures 1-9The diagram shown is a schematic representation of a preferred embodiment of the present invention, which relates to a coaxial dual-rotor motor that achieves coaxial dual power output. It comprises: a housing 1, a stator core 2, an inner rotor 3 with a first permanent magnet, and an outer rotor 4 with a second permanent magnet. The stator core is fixed inside the housing 1. The stator core 2 has a central hole 21 and inner slots 22 and outer slots 23 sequentially distributed around the central hole. A crossbeam 24 separates the inner slots 22 and outer slots 23. In this embodiment, the inner slots 22 and outer slots 23 are connected in an H-shape. Multiple inner and outer slots 22 and 23 are arranged circumferentially around the center of the central hole. After stator windings are assembled on the stator core 2, internal and external magnetic fields are constructed to drive the inner rotor 3 and outer rotor 4 to rotate, respectively. The inner rotor is embedded in the central hole 21 of the stator core 2 and supported by the outer shell 1, allowing it to rotate under the influence of an internal magnetic field. A radial safety air gap is provided between the inner rotor and the stator core to ensure normal rotation of the inner rotor. The inner rotor has a first output shaft 31 extending from the outer shell 1 to obtain power output. The outer rotor 4 is sleeved on the outer circumference of the stator core 2 and supported by the outer shell 1, allowing it to rotate under the influence of an external magnetic field. A radial safety air gap is also provided between the outer rotor and the stator core to ensure normal rotation of the outer rotor. The outer rotor has a second output shaft 41 extending from the outer shell 1. The second output shaft 41 is hollow and sleeved on the first output shaft 31, so that the second output shaft 41 and the first output shaft 31 extend coaxially and in the same direction. The second output shaft 41 and the first output shaft 31 can rotate in the same or opposite directions to obtain dual power output to meet the needs of different occasions.

[0019] Furthermore, the outer rotor 4 is designed as a U-shape, providing good overall structural integrity. The second permanent magnet is attached to the inner side of the U-shape, and the first output shaft 31 passes through the interior of the outer rotor 4. A first bearing 51 is embedded between the first output shaft 31 and the outer rotor 4. Specifically, a countersunk hole is added to the inner bottom of the U-shape to allow the first bearing 51 to be embedded and assembled, ensuring stable and reliable assembly. The other end of the inner rotor 3 is positioned on the outer casing 1 via a third bearing 53, achieving coaxial positioning and rotational support for both ends of the inner rotor, thus ensuring smooth rotation of the inner rotor. The interior of the second output shaft 41 of the outer rotor 4 is coaxially connected to the first output shaft 31 via the first bearing 51. Simultaneously, a second bearing 52 is embedded between the outer side of the second output shaft 41 and the outer casing 1. The clamping of the second output shaft 41 by the inner and outer bearings not only increases the installation stability of the outer rotor 4 but also ensures that the second output shaft 41 rotates coaxially with the first output shaft 31. This structural design, through the bearings, effectively withstands the absolute speed, eliminates the torque transmitted from the load end, greatly extends the mechanical life, and reduces vibration.

[0020] In this embodiment, the second output shaft 41 is further designed to be formed by the axial connection of a fixed section 411 and a movable section 412. The fixed section 411 is integrally formed with the outer rotor 4, and the movable section 412 is screwed onto the fixed section. Simultaneously, an annular groove is formed on the outer periphery of the connection area between the fixed section 411 and the movable section 412. This annular groove is adapted to the inner ring of the second bearing 52 for embedding and assembly, increasing positioning and tightness of the connection. This structural design facilitates manufacturing and assembly, and also facilitates disassembly and maintenance. This embodiment further adds a retaining ring 13 to the outer casing 1. This retaining ring 13 further presses against the second bearing 52, improving assembly firmness and further enhancing smooth rotation.

[0021] The above embodiments are described using the first bearing 51, the second bearing 52, and the third bearing 53 as examples. Of course, in actual production, copper bushings, Teflon pads, or POM pads (commonly known as "super steel" or "acetal steel", also known as polyoxymethylene) can be used to replace the bearings, which can also achieve the effect of ensuring rotation while isolating and absorbing vibration. These will not be illustrated in detail here.

[0022] In this embodiment, to facilitate manufacturing and assembly, and to ensure product structural performance, the outer casing 1 is designed to consist of a cylindrical shell 11 and a bottom cover 12. The cylindrical shell 11 is fixed together with the bottom cover 12 after housing the stator core 2, the inner rotor 3, and the outer rotor 4. The first output shaft 31 and the second output shaft 41 extend from the cylindrical shell 11. The bottom cover 12 is in the form of a flange, with an outwardly flared edge 111 on the cylindrical shell 11. This edge 111 is connected to the bottom cover 12 by a second bolt 62, resulting in a simple structure that is easy to assemble and disassemble. The inner side of the bottom cover 12 has multiple circumferentially distributed support steps 121. These support steps 121 press against the corresponding ends of the stator core 2, leaving a gap between the bottom cover 12 and the stator core 2, which facilitates heat dissipation and assembly. The stator core 2 also has an axially penetrating positioning hole 25. The first bolt 61 passes through the positioning hole 25 and is locked to the bottom cover 12. In conjunction with the connection between the cylindrical shell 11 and the bottom cover 12, the stator core 2 is fixed inside the outer shell 1. This structure can effectively eliminate second-order mechanical vibration and improve usability and lifespan.

[0023] Figure 8As shown, the stator core 2 of this invention can be designed with the same number of inner slots 22 and outer slots 23, and the inner slots 22 and outer slots 23 are arranged one-to-one collinearly in the radial direction of the stator core 2. In this case, the stator windings are separately set on the crossbeam 24 to construct the inner and outer magnetic fields. With a symmetrical design, the inner slots 22 and outer slots 23 respectively construct the inner and outer ring pole shoes, and the inner and outer slots maintain strict symmetry in pole arc coefficient, geometric area, and air gap. Only a single excitation coil A is wound on the H-shaped crossbeam. The magnetic flux generated by this single excitation coil is naturally shunt at the two pole shoes, synchronously driving the inner and outer rotors, greatly reducing the total amount of copper wire used. When the motor performs coaxial counter-current operation, the radial alternating magnetic pull generated by the inner and outer rotors directly undergoes 100% physical counter-current within the rigid crossbeam, eliminating alternating stress from the source.

[0024] like Figure 9 As shown, the stator core 2 of the present invention can also be designed with different numbers of inner slots 22 and outer slots 23, and the inner slots 22 and outer slots 23 are evenly distributed around the center of the central hole. In this case, the stator windings are respectively set on the corresponding slot walls of the inner slots 22 and outer slots 23 to construct the inner magnetic field and the outer magnetic field. The asymmetrical design artificially breaks the symmetry of the inner and outer sides of the H-shaped stator core (for example, in this embodiment, the number of inner slots 22 is twelve and the number of outer slots 23 is eighteen). The single winding of the central beam is abandoned. The inner coil B is wound on the slot wall of the adjacent inner slot, and the outer coil C is wound on the slot wall of the adjacent outer slot. The beam acts as a physical isolation wall to ensure that the inner and outer coils flow in layers and directions within the ring, completely avoiding magnetic interference. Meanwhile, the adjacent coils on the inner slot 22 and the outer slot 23 are wound in alternating directions with one positive and one negative physical winding direction. The windings of the inner slot 22 and the outer slot 23 are controlled by independent phase sequence control logic. The static magnetic deadlock under the asymmetrical slot ratio is broken by the phase without power, so as to achieve independent dynamic balance between the inner rotor and the outer rotor.

[0025] During automated winding production, symmetrical stator cores can be directly wound at high speed on the crossbeam using a low-cost flying fork winding machine, achieving extremely high slot fill factor; while asymmetrical stator cores, due to their exposed slot design, are also conducive to automated winding, and integrated stamping ensures assembly concentricity.

[0026] The coaxial dual-rotor motor provided by this invention can independently complete complex composite processes without the need for external mechanical structures (such as planetary gear mechanisms, clutches, etc.). Multi-mode coaxial cleaning equipment, such as electric cleaning brushes, can achieve a variety of cleaning modes, including "outer stop and inner swing", "inner and outer frequency swing (large area rubbing and deep vibration synchronous)" or inner and outer bidirectional coaxial rotation.

[0027] Coaxial "clamping and screwing" work simultaneously, such as in an intelligent electric screwdriver: the outer rotor outputs a high-rigidity static holding torque to drive the gripper, while the inner rotor synchronously outputs a dynamic rotational torque to drive the screw.

[0028] Coaxial "feed and machining" dual-path control, such as precision medical bone drills / micro tapping: the outer rotor converts to linear feed to control depth, while the inner rotor provides continuous high-torque rotation to handle cutting.

[0029] Coaxial differential speed "spatial coordinate translation", such as micro gimbals / robot flexible joints: by using the differential speed ratio of the inner and outer rotors, the multi-dimensional coordinate translation driving force is compressed onto a single geometric axis.

[0030] This invention features a compact structure, facilitating low-cost mass production. Its small size, achieved by incorporating one stator and two rotors on the motor, allows for direct coaxial dual-power output. When used in product manufacturing, it eliminates the need for external planetary gear mechanisms, resulting in low production costs and a compact, user-friendly product. Furthermore, the coaxial counter-rotating output on the motor directly cancels out reaction forces and eliminates torque, effectively improving vibration and hand-held vibration issues, enhancing usability and user experience. It also offers stable, reliable operation and a long service life. In practical implementation, the end of the inner rotor opposite to the first output shaft can be fitted with a counterweight or fan to further enhance its practicality.

[0031] While preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention should not be limited to structures and operations that are exactly the same as those described above and shown in the drawings. Those skilled in the art can make many equivalent improvements and variations to the above embodiments through logical analysis, reasoning, or limited experiments without departing from the concept and scope of the present invention, but all such improvements and variations should fall within the scope of protection claimed by the present invention.

Claims

1. A coaxial dual-rotor motor, characterized in that, have: Outer shell (1), The stator core (2) is fixed inside the outer shell (1). The stator core (2) has a central hole (21) and inner wire slots (22) and outer wire slots (23) distributed around the central hole. There is a crossbeam (24) separating the inner wire slots (22) and the outer wire slots (23). There are multiple inner wire slots (22) and outer wire slots (23) arranged in a circle around the center of the central hole. After the stator winding is assembled on the stator core (2), an internal magnetic field and an external magnetic field are constructed. An inner rotor (3) with a first permanent magnet is embedded in the central hole (21) of the stator core (2) and supported by the outer shell (1), so that the inner rotor can rotate under the action of the internal magnetic field, and the inner rotor has a first output shaft (31) extending from the outer shell (1). An outer rotor (4) with a second permanent magnet is sleeved on the outer periphery of the stator core (2) and supported by the outer shell (1), so that the outer rotor can rotate under the action of an external magnetic field. The outer rotor has a second output shaft (41) extending from the outer shell (1). The second output shaft (41) is hollow and sleeved on the first output shaft (31), so that the second output shaft (41) and the first output shaft (31) extend out coaxially and in the same direction.

2. The coaxial dual-rotor motor according to claim 1, characterized in that, The outer rotor (4) is U-shaped. The first output shaft (31) passes through the interior of the outer rotor (4), and a first bearing (51) is embedded between the first output shaft (31) and the outer rotor (4). A second bearing (52) is embedded between the second output shaft (41) of the outer rotor (4) and the outer shell (1). The other end of the inner rotor (3) is positioned on the outer shell (1) by a third bearing (53).

3. A coaxial dual-rotor motor according to claim 1 or 2, characterized in that, The outer casing (1) has a cylindrical shell (11) and a bottom cover (12). The cylindrical shell (11) is fixed together with the bottom cover (12) after accommodating the stator core (2), the inner rotor (3) and the outer rotor (4). The first output shaft (31) and the second output shaft (41) extend out from the cylindrical shell (11).

4. A coaxial dual-rotor motor according to claim 3, characterized in that, The inner side of the bottom cover (12) has a plurality of circumferentially distributed support steps (121), which press against the corresponding ends of the stator core (2) to leave a gap between the bottom cover (12) and the stator core (2); the stator core (2) also has an axially penetrating positioning hole (25), through which the first bolt (61) passes and locks to the bottom cover (12) to fix the stator core (2) inside the outer shell (1).

5. A coaxial dual-rotor motor according to claim 3, characterized in that, The bottom cover (12) is in the form of a flange, and the cylindrical shell (11) has an outwardly flared edge (111), which is connected to the bottom cover (12) by a second bolt (62).

6. A coaxial dual-rotor motor according to claim 1, characterized in that, The number of inner slots (22) and outer slots (23) on the stator core (2) is the same, and the inner slots (22) and outer slots (23) are arranged one-to-one collinearly in the radial direction of the stator core (2). At this time, the stator winding is set separately on the crossbeam (24) to construct the inner magnetic field and the outer magnetic field.

7. A coaxial dual-rotor motor according to claim 1, characterized in that, The number of inner slots (22) and outer slots (23) on the stator core (2) is different, and the inner slots (22) and outer slots (23) are evenly distributed around the center of the central hole. At this time, the stator windings are respectively set on the corresponding slot walls of the inner slots (22) and outer slots (23) to construct the inner magnetic field and the outer magnetic field.

8. A coaxial dual-rotor motor according to claim 2, characterized in that, The second output shaft (41) is formed by axial connection of a fixed section (411) and a movable section (412). The fixed section (411) is integrally formed with the outer rotor (4). The movable section (412) is locked to the fixed section by screws. An annular groove is formed on the outer periphery of the connection area between the fixed section (411) and the movable section (412). The annular groove is adapted to be embedded and assembled into the inner ring of the second bearing (52).

9. The application of the coaxial dual-rotor motor according to any one of claims 1 to 8, for manufacturing electric cleaning brushes, beauty instruments, intelligent electric screwdrivers, precision medical bone drills, medical micro-tapping devices, micro-gimbal flexible joints, or robotic flexible joints.

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