Hollow cup motor

Abstract

The application is suitable for the technical field of hollow cup motor, and provides a hollow cup motor, which comprises a shell assembly, a rotor assembly and a stator assembly. The rotor assembly comprises a permanent magnet rotor, the permanent magnet rotor is rotatably arranged in the shell assembly, the stator assembly comprises a stator wire cup and a stator core, the stator wire cup is coaxially arranged outside the permanent magnet rotor, and the stator core is coaxially arranged outside the stator wire cup. A magnetic resistance modulation structure is arranged on the stator core, the magnetic resistance modulation structure is used for locally changing the air gap permeance distribution between the permanent magnet rotor and the stator core, and the permanent magnet rotor and the stator core have the air gap with asymmetric distribution, so that the hollow cup motor can generate the cogging torque.

Description

[0001] This application claims priority to Chinese Patent Application No. 2025211944091, filed on June 11, 2025, entitled "Hollow Cup Motor", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of hollow cup motor technology, and more specifically, relates to a hollow cup motor. Background Technology

[0003] Traditional coreless motors have advantages such as energy saving, good control characteristics, and stable driving characteristics, and are widely used in high-precision drive fields such as drones, medical devices, and robots.

[0004] However, existing coreless motors lack cogging torque, which means they cannot provide self-positioning torque after power failure, limiting their application in scenarios requiring position holding or reverse driving resistance. Utility Model Content

[0005] The purpose of this application is to provide a hollow cup motor, which aims to solve the technical problem that the hollow cup motor in the prior art has no cogging torque and its application scenarios are limited.

[0006] To achieve the above objectives, according to one aspect of this application, a hollow cup motor is provided. The hollow cup motor includes: a housing assembly, a rotor assembly, and a stator assembly. The rotor assembly includes a permanent magnet rotor rotatably disposed within the housing assembly. The stator assembly includes a stator coil and a stator core. The stator coil is coaxially sleeved on the outside of the permanent magnet rotor, and the stator core is coaxially sleeved on the outside of the stator coil. A reluctance modulation structure is provided on the stator core. The reluctance modulation structure is used to locally change the air gap magnetic permeability distribution between the permanent magnet rotor and the stator core, and to create an asymmetrically distributed air gap between the permanent magnet rotor and the stator core, so that the hollow cup motor can generate cogging torque.

[0007] Optionally, the reluctance modulation structure includes at least one first groove disposed on the inner sidewall of the stator core near the permanent magnet rotor; and / or, the reluctance modulation structure includes at least one second groove disposed on the outer sidewall of the stator core opposite to the permanent magnet rotor; and / or, the reluctance modulation structure includes at least one modulation hole disposed on the stator core and located between the inner sidewall and the outer sidewall of the stator core.

[0008] Optionally, there may be multiple first grooves, which are spaced apart circumferentially along the stator core; and / or, there may be multiple second grooves, which are spaced apart circumferentially along the stator core; and / or, there may be multiple modulation holes, which are spaced apart circumferentially along the stator core.

[0009] Optionally, there are multiple first grooves, which are equally spaced along the circumference of the stator core; and / or, there are multiple second grooves, which are equally spaced along the circumference of the stator core; and / or, there are multiple modulation holes, which are equally spaced along the circumference of the stator core.

[0010] Optionally, the magnetoresistive modulation structure includes a first groove, the extension direction of which is parallel to the axial direction of the stator core; and / or, the magnetoresistive modulation structure includes a second groove, the extension direction of which is parallel to the axial direction of the stator core; and / or, the magnetoresistive modulation structure includes a modulation hole, the extension direction of which is parallel to the axial direction of the stator core.

[0011] Optionally, the first groove connects the two opposite sides of the stator core in the axial direction; and / or, the second groove connects the two opposite sides of the stator core in the axial direction; and / or, the modulation hole connects the two opposite sides of the stator core in the axial direction.

[0012] Optionally, the cross-sectional profile of the first groove perpendicular to the extension direction is formed by at least one arc, or by at least two straight line segments, or by a combination of at least one straight line segment and at least one arc segment; and / or, the cross-sectional profile of the second groove perpendicular to the extension direction is formed by at least one arc, or by at least two straight line segments, or by a combination of at least one straight line segment and at least one arc segment; and / or, the cross-sectional profile of the modulation hole perpendicular to the extension direction is circular, or a polygon formed by at least three straight line segments, or a closed profile formed by a combination of at least one straight line segment and at least one arc segment.

[0013] Optionally, the housing assembly includes a housing and an end cover, the end cover being mounted on the housing, and a receiving cavity being formed between the end cover and the housing, wherein the permanent magnet rotor and stator assembly are both located within the receiving cavity.

[0014] Optionally, the rotor assembly further includes a first bearing and a second bearing, wherein the first end of the permanent magnet rotor is rotatably connected to the housing via the first bearing, and the second end of the permanent magnet rotor is rotatably connected to the end cover via the second bearing; wherein the first bearing and the second bearing are coaxially arranged.

[0015] Optionally, the coreless motor also includes a temperature detection component disposed on the end cover. The temperature detection component has a sensing part that contacts the side of the stator assembly near the end cover.

[0016] The beneficial effects of the hollow cup motor provided in this application are as follows: Compared with the prior art, the hollow cup motor provided in this application, by setting a reluctance modulation structure on the stator core, locally changes the air gap magnetic permeability distribution between the permanent magnet rotor and the stator core, forming an asymmetric air gap magnetic field. Without significantly increasing the motor volume or losses, it effectively generates controllable cogging torque. It retains the advantages of high efficiency and low inertia of traditional hollow cup motors, and solves the technical problem that the rotor assembly of the hollow cup motor cannot self-position after power failure. It significantly improves the applicability of the hollow cup motor in scenarios requiring position holding or reverse resistance. Furthermore, by optimizing the air gap magnetic permeability distribution, the reluctance modulation structure can also precisely adjust the magnitude of the cogging torque and the positioning angle, taking into account both the dynamic performance and static positioning requirements of the hollow cup motor. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a hollow cup motor provided in an embodiment of this application;

[0019] Figure 2 A schematic diagram of a hollow cup motor with some components removed, provided as an embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the stator core structure provided in an embodiment of this application;

[0021] Figure 4 This is a schematic diagram of the stator core structure provided in another embodiment of this application;

[0022] Figure 5 A schematic diagram of the stator core provided in another embodiment of this application;

[0023] The details of the reference numerals used in the above figures are as follows:

[0024] 10. Housing assembly; 11. Housing; 12. End cap;

[0025] 21. Permanent magnet rotor;

[0026] 32. Stator core; 3211. First groove; 3212. Second groove; 3213. Modulation hole. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0028] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly or indirectly on that other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to that other element. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0031] As described in the background section, traditional coreless motors have advantages such as energy saving, good control characteristics, and stable driving characteristics, and are widely used in high-precision drive fields such as drones, medical devices, and robots. However, existing coreless motors lack cogging torque, which means they cannot provide self-positioning torque after power failure, limiting their application in scenarios requiring position holding or reverse driving resistance.

[0032] See Figures 1 to 5As shown, in order to solve the above problems, according to one aspect of this application, an embodiment of this application provides a hollow cup motor. The hollow cup motor includes: a housing assembly 10, a rotor assembly, and a stator assembly. The rotor assembly includes a permanent magnet rotor 21, which is rotatably disposed within the housing assembly 10. The stator assembly includes a stator coil and a stator core 32. The stator coil is coaxially sleeved on the outside of the permanent magnet rotor 21, and the stator core 32 is coaxially sleeved on the outside of the stator coil. The stator core 32 is provided with a reluctance modulation structure, which is used to locally change the air gap magnetic permeability distribution between the permanent magnet rotor 21 and the stator core 32, and to make the air gap between the permanent magnet rotor 21 and the stator core 32 asymmetrically distributed, so that the hollow cup motor can generate cogging torque. The coreless motor provided in this embodiment, by setting a reluctance modulation structure on the stator core 32, locally changes the air gap magnetic permeability distribution between the permanent magnet rotor 21 and the stator core 32, forming an asymmetric air gap magnetic field. Without significantly increasing the motor volume or losses, it effectively generates controllable cogging torque. It retains the advantages of high efficiency and low inertia of traditional coreless motors, while solving the technical problem that the rotor assembly of the coreless motor cannot self-position after power failure. It significantly improves the applicability of the coreless motor in scenarios requiring position holding or reverse resistance. Furthermore, by optimizing the air gap magnetic permeability distribution, the reluctance modulation structure can also precisely adjust the magnitude of the cogging torque and the positioning angle, taking into account both the dynamic performance and static positioning requirements of the coreless motor.

[0033] It should be noted that the reluctance modulation structure in this embodiment refers to a specific physical structure set on the stator core 32. It changes the reluctance characteristics of the local magnetic circuit between the stator assembly and the rotor assembly, so that the air gap magnetic field presents a non-uniform distribution in the circumference. The asymmetrical air gap refers to the difference in air gap permeability at different circumferential positions between the permanent magnet rotor 21 and the stator core 32 due to the presence of the reluctance modulation structure, thereby forming a physical gap with spatial asymmetry in magnetic field strength. The cogging torque refers to the periodic positioning torque caused by the asymmetry of the air gap magnetic field. Its amplitude is related to the geometric parameters and spatial distribution of the reluctance modulation structure, which can make the rotor assembly stably stay at a preset angle position when the power is off.

[0034] See Figure 3As shown, in a specific embodiment, the reluctance modulation structure includes at least one first groove 3211, which is disposed on the inner wall of the stator core 32 near the permanent magnet rotor 21. By setting the first groove 3211 on the inner wall of the stator core 32, precise control of the air gap magnetic field is achieved. The first groove 3211 significantly reduces the permeability of the area by locally increasing the air gap distance, thereby forming an asymmetrical reluctance distribution in the circumference of the permanent magnet rotor 21. Selective reluctance modulation can enable the hollow cup motor to generate controllable cogging torque during operation. The torque amplitude is directly related to the geometric parameters of the groove. Compared with the overall structural modification, this embodiment only requires local processing of the stator core 32, which not only retains the original high efficiency characteristics of the hollow cup motor, but also realizes the self-positioning function of the rotor assembly in the power-off state.

[0035] It is understandable that by adjusting the depth, width, and circumferential position of the first groove 3211, the amplitude and balance position of the positioning torque can be flexibly adjusted to meet the differentiated requirements of positioning accuracy and holding torque for different application scenarios.

[0036] See Figure 4 As shown, in a specific embodiment, the magnetoresistive modulation structure includes at least one second groove 3212, which is disposed on the outer side wall of the stator core 32 opposite to the permanent magnet rotor 21. By providing the second groove 3212 on the outer side wall of the stator core 32, indirect control of the magnetic reluctance of the magnetic circuit is achieved. The second groove 3212 indirectly affects the distribution characteristics of the air gap magnetic field between the stator and rotor by changing the magnetic flux path on the outside of the stator core 32, thereby forming a specific asymmetric magnetic reluctance distribution in the circumference of the permanent magnet rotor 21, compared to... The inner first groove 3211 and the second groove 3212 in this embodiment can avoid direct interference with the main working air gap, effectively reducing the impact on the dynamic performance of the coreless motor. The processing technology of the second groove 3212 located on the outer wall of the stator core 32 is simpler, and there is no need to consider the rotor motion interference problem. Furthermore, by adjusting the geometric parameters of the second groove 3212, the cogging torque characteristics can be remotely controlled, ensuring that sufficient positioning torque is generated while maintaining the original high efficiency and low inertia core characteristics of the coreless motor to the greatest extent.

[0037] See Figure 5As shown, in a specific embodiment, the magnetoresistive modulation structure in this embodiment includes at least one modulation hole 3213, which is disposed in the stator core 32 and located between the inner sidewall and the outer sidewall of the stator core 32. By setting modulation holes 3213 inside the stator core 32, three-dimensional control of the magnetic circuit is achieved. The modulation holes 3213 locally change the magnetic permeability distribution of the stator core 32, simultaneously modulating the air gap magnetic field in the radial and circumferential directions, forming a magnetic reluctance distribution with spatial gradient characteristics. Compared with the surface groove structure, the modulation holes 3213 located inside the stator core 32 can simultaneously affect the inner and outer magnetic circuits, achieving more precise control of the magnetic field waveform, avoiding the formation of mechanical defects on the working surface of the stator assembly, maintaining the integrity of the air gap surface, and by adjusting the axial position, radial depth, and circumferential distribution of the modulation holes 3213, the harmonic components of the torque waveform can be independently adjusted. While generating the required cogging torque, the additional losses are minimized to the greatest extent, enabling the motor to have both superior dynamic performance and precise static positioning capability.

[0038] See Figure 3 As shown, in a specific embodiment, there are multiple first grooves 3211, which are spaced apart circumferentially along the stator core 32. By circumferentially spaced multiple first grooves 3211 on the inner sidewall of the stator core 32, periodic modulation of the air gap magnetic field is achieved. Through the synergistic effect of each first groove 3211, a regularly distributed magnetic reluctance change is formed in the circumferential direction of the permanent magnet rotor 21, generating a cogging torque with specific harmonic characteristics. By optimizing the spacing and number of the first grooves 3211, the periodicity and amplitude of the torque waveform can be precisely controlled, making the positioning angle distribution more uniform. At the same time, it can flexibly match the positioning requirements of rotor assemblies with different pole pairs. While ensuring effective positioning, it significantly improves the torque imbalance problem caused by a single first groove 3211.

[0039] See Figure 4As shown, in a specific embodiment, there are multiple second grooves 3212, which are spaced apart circumferentially along the stator core 32. By circumferentially spaced multiple second grooves 3212 on the outer sidewall of the stator core 32, multi-point precise control of the magnetic circuit is achieved. By coordinating the magnetic flux path of the stator core 32 through each second groove 3212, a periodically changing equivalent reluctance network can be constructed in the circumferential direction of the permanent magnet rotor 21, thereby generating a positioning torque with an optimized waveform. Through the spaced distribution of multiple second grooves 3212, a composite modulation effect can be formed, and the periodicity and amplitude characteristics of the torque waveform can be precisely set. The layout of the outer second grooves 3212 can avoid interfering with the main working air gap of the coreless motor, and maintain the dynamic performance stability of the coreless motor while generating positioning torque. By adjusting the spacing and distribution phase of the second grooves 3212, torque harmonics of a specific order can be effectively suppressed, and the angular deviation during rotor assembly positioning can be reduced.

[0040] See Figure 5 As shown, in a specific embodiment, there are multiple modulation holes 3213, which are spaced apart circumferentially along the stator core 32. By circumferentially spaced multiple modulation holes 3213 within the stator core 32, periodic modulation of the three-dimensional magnetic circuit is achieved. By synergistically changing the permeability distribution inside the core through the modulation holes 3213, a gradient magnetoresistive network can be constructed circumferentially on the permanent magnet rotor 21, thereby generating a cogging torque with optimized waveform characteristics. By adjusting the spacing and radial depth of the modulation holes 3213, the harmonic components of the torque waveform can be precisely controlled, thereby strengthening the positioning torque while suppressing harmful vibrations. The internal modulation hole 3213 structure can simultaneously affect the axial, radial, and circumferential magnetic flux paths, achieving finer magnetic field waveform shaping. The number, distribution, and phase of the modulation holes 3213 can independently adjust the dynamic torque pulsation and static holding torque, meeting the dual requirements of motion smoothness and positioning stability.

[0041] See Figure 3As shown, in a specific embodiment, there are multiple first grooves 3211, which are equally spaced along the circumference of the stator core 32. By equally spaced multiple first grooves 3211 on the inner sidewall of the stator core 32, the periodic and precise modulation of the air gap magnetic field is achieved. The equally spaced array of first grooves 3211 can form a regular magnetic reluctance change in the circumference of the permanent magnet rotor 21, generating optimized cogging torque characteristics. The equally spaced arrangement can effectively eliminate harmful torque harmonics and enhance the target positioning harmonic components. Through the matching design of the number of first grooves 3211 and the number of motor pole pairs, the rotor assembly can obtain a stable preset angle positioning capability. The symmetrically distributed structure of the first grooves 3211 not only simplifies the processing technology but also ensures the smooth operation of the motor.

[0042] See Figure 4 As shown, in a specific embodiment, there are multiple second grooves 3212, which are equally spaced along the circumference of the stator core 32. By equally spaced multiple second grooves 3212 on the outer wall of the stator core 32, the periodic optimization and control of the magnetic circuit characteristics are realized. The equally spaced array of second grooves 3212 coordinately adjusts the magnetic flux path on the outer side of the stator core 32, forming a regular equivalent magnetic reluctance change on the circumference of the permanent magnet rotor 21, effectively suppressing specific order torque harmonics and significantly reducing torque pulsation during the operation of the hollow cup motor. At the same time, the symmetrically distributed structure of the second grooves 3212 can optimize the magnetic permeability distribution of the outer magnetic circuit of the stator core 32, and realize the precise positioning function of the rotor assembly after power failure without interfering with the main working air gap.

[0043] See Figure 5 As shown, in a specific embodiment, there are multiple modulation holes 3213, which are equally spaced along the circumference of the stator core 32. By equally spaced multiple modulation holes 3213 inside the stator core 32, periodic symmetrical modulation of the three-dimensional magnetic circuit is achieved. The equally spaced array of modulation holes 3213 collaboratively changes the magnetic permeability distribution inside the core, constructing a uniform gradient reluctance network in the circumference of the permanent magnet rotor 21, effectively suppressing harmful torque harmonic components and significantly reducing the operating vibration of the hollow cup motor. At the same time, the symmetrically distributed modulation hole 3213 structure, through precise control of the radial and circumferential magnetic flux paths, achieves multi-angle precise positioning of the rotor after power failure without affecting the main air gap magnetic field.

[0044] See Figure 3As shown, in a specific embodiment, the reluctance modulation structure includes a first groove 3211, the extension direction of which is parallel to the axial direction of the stator core 32. By setting the first groove 3211 to be parallel to the axial direction of the stator core 32, a reluctance modulation effect uniformly distributed along the axial direction of the coreless motor is achieved, so that the air gap magnetic field maintains a consistent modulation characteristic in the axial direction. This ensures the stability of the cogging torque throughout the entire effective length and avoids the axial force imbalance problem caused by skewed slots or variable depth structures. Furthermore, the axially parallel first groove 3211 can be formed in one step through standardized axial processing technology, which significantly improves production efficiency and dimensional consistency, while maintaining the original high dynamic response characteristics of the coreless motor.

[0045] See Figure 4 As shown, in a specific embodiment, the magnetoresistive modulation structure includes a second groove 3212, the extension direction of which is parallel to the axial direction of the stator core 32. By setting the extension direction of the second groove 3212 to be parallel to the axial direction of the stator core 32, a uniform axial magnetoresistive modulation characteristic can be formed on the outer wall of the stator core 32. By adjusting the magnetic permeability distribution of the outer magnetic circuit of the stator core 32, the cogging torque is ensured to be uniformly distributed along the axial direction of the hollow cup motor without affecting the main air gap magnetic field. This ensures the stability of the cogging torque throughout the entire effective length and avoids the axial force imbalance problem caused by skewed slots or variable depth structures. Furthermore, the axially parallel second groove 3212 can be formed in one step through standardized axial processing technology, which significantly improves production efficiency and dimensional consistency while maintaining the original high dynamic response characteristics of the hollow cup motor.

[0046] See Figure 5 As shown, in a specific embodiment, the magnetoresistive modulation structure includes a modulation hole 3213, the extension direction of which is parallel to the axial direction of the stator core 32. By setting the extension direction of the modulation hole 3213 to be parallel to the axial direction of the stator core 32, axial consistency modulation of the three-dimensional magnetic circuit is achieved, ensuring the continuity of the air gap magnetic field modulation in the axial direction, eliminating torque fluctuations caused by traditional discrete holes. The modulation hole 3213, parallel to the axial direction, facilitates drilling or EDM processes, significantly improving machining accuracy and production efficiency. At the same time, through symmetrical modulation of the internal magnetic circuit, stable cogging torque output is achieved without introducing additional axial electromagnetic force.

[0047] See Figure 3As shown, in a specific embodiment, the first groove 3211 in this embodiment connects the two opposite sides of the stator core 32 in the axial direction. By setting the first groove 3211 to connect the two opposite sides of the stator core 32 in the axial direction, uniform magnetic reluctance modulation is achieved throughout the entire axial range. The axially continuous first groove 3211 establishes a uniform magnetic reluctance change throughout the entire length of the stator core 32, eliminating the axial magnetic field distortion caused by segmented grooves. The first groove 3211 connecting the two opposite sides of the stator core 32 in the axial direction can be formed in one step by broaching or wire cutting process, which greatly improves processing efficiency and reduces manufacturing cost. At the same time, by establishing a completely consistent magnetic circuit modulation characteristic in the axial direction, while generating stable cogging torque, additional losses caused by local magnetic flux saturation are avoided.

[0048] See Figure 4 As shown, in a specific embodiment, the second groove 3212 in this embodiment connects the two opposite sides of the stator core 32 in the axial direction. By setting the second groove 3212 to connect the two opposite sides of the stator core 32 in the axial direction, the complete modulation of the magnetic circuit on the outer side of the stator core 32 along the axial direction is achieved. The axially continuous second groove 3212 establishes a uniform magnetic resistance change throughout the entire length of the stator core 32, eliminating the axial magnetic field distortion caused by segmented grooves. The second groove 3212 connecting the two opposite sides of the stator core 32 in the axial direction can be formed in one step by broaching or wire cutting process, which greatly improves processing efficiency and reduces manufacturing cost.

[0049] See Figure 5 As shown, in a specific embodiment, the modulation hole 3213 connects the two opposite sides of the stator core 32 in the axial direction. By setting the modulation hole 3213 to connect the two opposite sides of the stator core 32 in the axial direction, three-dimensional uniform modulation of the internal magnetic circuit of the stator core 32 is achieved. In this embodiment, the modulation hole 3213 forms a continuous permeability variation channel in the axial direction of the stator core 32, ensuring the integrity and consistency of the magnetic field modulation in the axial direction, effectively eliminating the problem of magnetic circuit discontinuity caused by traditional blind hole structures. The modulation hole 3213 connecting the two opposite sides of the stator core 32 in the axial direction can be formed in one step by deep hole drilling or electrical discharge machining, which greatly improves processing efficiency and reduces manufacturing costs.

[0050] See Figure 3 As shown, in a specific embodiment, the cross-sectional profile of the first groove 3211 in this embodiment is composed of at least one arc line in the direction perpendicular to the extension direction; by setting the cross-sectional profile of the first groove 3211 to an arc configuration, smooth modulation of the air gap magnetic field is achieved. The arc profile can effectively reduce the local saturation effect caused by the sudden change in magnetic flux, and significantly reduce the harmonic distortion rate of the air gap magnetic field; the smooth curved surface structure avoids magnetic field concentration caused by sharp corners, and reduces torque fluctuation when the rotor assembly is positioned.

[0051] In another embodiment, the cross-sectional profile of the first groove 3211 in this embodiment is composed of at least two straight line segments perpendicular to the extension direction. By setting the cross-sectional profile of the first groove 3211 to a straight line segment configuration, controllable modulation of magnetic reluctance is achieved. The straight line profile can form a clear magnetic flux boundary, making the air gap magnetic permeability change more directional and predictable. The segmented straight line profile can flexibly adjust the local magnetic reluctance gradient by adjusting the included angle, thereby achieving artificial shaping of the tooth cogging torque waveform.

[0052] In another embodiment, the cross-sectional profile of the first groove 3211 in this embodiment, perpendicular to the extension direction, is composed of a combination of at least one straight segment and at least one arc segment. The straight segment can provide a clear magnetic flux guiding boundary to ensure the directional controllability of magnetoresistive modulation, while the arc segment smoothly transitions the magnetic field distribution, effectively suppressing local magnetic saturation and torque pulsation. The straight part facilitates precise control of the amplitude characteristics of the cogging torque, while the curved part optimizes the magnetic field harmonic components, balancing the positioning accuracy and running stability of the coreless motor.

[0053] See Figure 4 As shown, in a specific embodiment, the cross-sectional profile of the second groove 3212 in this embodiment is composed of at least one arc line in the direction perpendicular to the extension direction; by setting the cross-sectional profile of the second groove 3212 to an arc configuration, the smooth modulation of the outer magnetic circuit is realized. The arc profile can effectively guide the smooth change of the outer magnetic flux and avoid the local eddy current loss caused by the sudden change of the magnetic circuit; the curved structure significantly reduces the harmonic components of the air gap magnetic field and reduces the angle jitter when the rotor assembly is positioned.

[0054] In another embodiment, the cross-sectional profile of the second groove 3212 in this embodiment is composed of at least two straight line segments in the direction perpendicular to the extension direction. By setting the cross-sectional profile of the second groove 3212 to a multi-straight line segment configuration, controllable modulation of the outer magnetic reluctance is achieved. The straight line profile can form a directional magnetic flux blocking boundary, enhancing the predictability of local magnetic reluctance changes. The geometric features composed of segmented straight lines can flexibly adjust the equivalent air gap permeability by adjusting the included angle, thereby achieving step-like shaping of the tooth cogging torque waveform.

[0055] In another embodiment, the cross-sectional profile of the second groove 3212 in this embodiment is composed of a combination of at least one straight segment and at least one arc segment in the direction perpendicular to the extension. By setting the cross-sectional profile of the second groove 3212 as a combination of straight segment and arc segment, the coordinated optimization modulation of the outer magnetic circuit is realized. The straight segment provides a clear magnetic flux guiding boundary to ensure the precise controllability of magnetic reluctance changes. The arc segment smoothly transitions the magnetic field distribution and effectively suppresses harmonic torque pulsation.

[0056] See Figure 5As shown, in a specific embodiment, the modulation hole 3213 in this embodiment has a circular cross-sectional profile perpendicular to the extension direction. By designing the cross-sectional profile of the modulation hole 3213 as a circle, the isotropic optimization of magnetic circuit modulation is achieved. The circular profile, through its axisymmetric characteristics, forms a uniform magnetic permeability distribution inside the stator core 32, effectively eliminating the influence of directional magnetic reluctance abrupt change on the magnetic field. The smooth circular profile not only avoids stress concentration and improves structural reliability, but also significantly simplifies the processing technology.

[0057] In another embodiment, the cross-sectional profile of the modulation aperture 3213 in this embodiment is a polygon formed by at least three straight line segments in the direction of extension. By setting the cross-sectional profile of the modulation aperture 3213 to a polygonal configuration, the directional controllability of magnetoresistive modulation is realized. The profile enclosed by straight line segments not only facilitates the use of standardized processing technology, but also enables predictable modulation of magnetic circuit characteristics through specific angle design.

[0058] In another embodiment, the modulation aperture 3213 in this embodiment has a closed profile in the cross-sectional profile perpendicular to the extension direction, formed by a combination of at least one straight line segment and at least one arc segment. By setting the cross-sectional profile of the modulation aperture 3213 as a combination of straight line segments and arc segments, the synergistic optimization of magnetoresistive modulation characteristics is achieved. The straight line segment can provide a clear magnetic flux guiding boundary, ensuring the precise controllability of magnetoresistive changes, while the arc segment can smoothly transition the magnetic field distribution, effectively suppressing torque pulsation caused by high-frequency harmonics. While improving the stability of cogging torque, it avoids magnetic flux distortion at the polygonal corners, thus balancing electromagnetic performance and structural reliability.

[0059] See Figure 1 and Figure 2 As shown, in one specific embodiment, the housing assembly 10 includes a housing 11 and an end cover 12. The end cover 12 is mounted on the housing 11, and a receiving cavity is formed between the end cover 12 and the housing 11. The permanent magnet rotor 21 and the stator assembly are both located within the receiving cavity. Positioning the permanent magnet rotor 21 and the stator assembly within the receiving cavity effectively protects them, improves the reliability of the coreless motor under complex operating conditions, and facilitates the assembly and maintenance of the coreless motor, significantly reducing manufacturing costs.

[0060] In one specific embodiment, the rotor assembly further includes a first bearing and a second bearing. The first end of the permanent magnet rotor 21 is rotatably connected to the housing 11 via the first bearing, and the second end of the permanent magnet rotor 21 is rotatably connected to the end cover 12 via the second bearing. The first and second bearings are coaxially arranged. By supporting both ends of the rotor assembly with the coaxially arranged first and second bearings, precise axial and radial alignment of the rotor assembly can be ensured, effectively suppressing vibration and sway during high-speed operation and ensuring reliable operation of the rotor assembly.

[0061] In one specific embodiment, the coreless motor further includes a temperature detection component disposed on the end cover 12. The temperature detection component has a sensing part that contacts the side of the stator assembly near the end cover 12. By setting the temperature detection component on the end cover 12 and having its sensing part directly contact the end of the stator assembly, real-time monitoring of the operating temperature of the coreless motor is achieved, improving the reliability of the coreless motor.

[0062] In some embodiments, the temperature detection component in this embodiment includes a circuit board and a temperature sensor. The circuit board is disposed on the end cover 12, and the temperature sensor is electrically connected to the circuit board to form the sensing part of the temperature detection component.

[0063] In some embodiments, the circuit board in this embodiment includes a flexible circuit board and a rigid circuit board. The stator coil and temperature sensor are both electrically connected to the flexible circuit board. The flexible circuit board is used to control the operation of the stator coil and temperature sensor. The rigid circuit board is electrically connected to the flexible circuit board. The hollow cup motor in this embodiment also includes an encoder. The encoder and rotor assembly are both electrically connected to the rigid circuit board. An external controller can be electrically connected to the rigid circuit board and control the operation of the rotor assembly through the encoder.

[0064] In some embodiments, the permanent magnet rotor 21 in this embodiment includes a rotating shaft, a first bushing, a second bushing, and a rotor magnet. The first bushing, the second bushing, and the rotor magnet are all sleeved on the outside of the rotating shaft. The first bushing and the second bushing are both interference-fitted with the rotating shaft and respectively abut against the opposite sides of the rotor magnet in the axial direction to fix the rotor magnet to the rotating shaft. The two ends of the rotating shaft form the two ends of the permanent magnet rotor 21. In this embodiment, a first clearance through hole is provided on the end of the housing 11 away from the end cover 12, and a second clearance through hole is provided on the end cover 12. The two ends of the rotating shaft pass through the first clearance through hole and the second clearance through hole to exit the receiving cavity. In this embodiment, the first bearing is installed in the first clearance through hole, and the second bearing is installed in the second clearance through hole.

[0065] In some embodiments, a compression spring is provided in the second clearance through hole in this embodiment. The two ends of the compression spring abut against the second bearing and the end cover, respectively, to apply a spring force close to the shaft assembly to the second bearing, so as to reduce the probability of the second bearing moving axially relative to the rotor assembly.

[0066] In some embodiments, an O-ring is provided between the second clearance through hole and the second bearing in this embodiment. The O-ring is used to seal the gap between the second clearance through hole and the second bearing to improve the reliability of the coreless motor.

[0067] In some embodiments, the stator assembly in this embodiment further includes a first washer and a second washer. The first washer is disposed at the end of the stator spool away from the end cap and abuts against the side of the stator core away from the end cap. The second washer is sleeved on the stator spool and located at the end of the stator spool near the end cap, and abuts against the side of the stator core near the end cap. Through the abutment of the first washer and the second washer against the stator core, the stator core can be axially confined within the stator spool.

[0068] In one specific embodiment, the hollow cup motor has a high energy conversion efficiency, with a maximum efficiency generally above 70%, and some products reaching over 90%. It starts and brakes quickly, with an extremely fast response and a mechanical time constant of less than 28 milliseconds, with some products achieving less than 10 milliseconds. Under high-speed operation within the recommended operating range, the speed can be easily and sensitively adjusted, and the operation is stable and reliable with very small speed fluctuations. As a micro motor, its speed fluctuation can be easily controlled within 2%. In addition, the energy density of the hollow cup motor is significantly improved. Compared with an iron core motor of the same power, its weight and volume are reduced by 1 / 3 to 1 / 2. At the same time, it can generate a certain amount of counter-drive force and self-locking force after the motor is powered off, so as to adapt to the working conditions that require cogging torque.

[0069] In summary, implementing the hollow cup motor provided in this embodiment has at least the following beneficial technical effects: The hollow cup motor provided in this embodiment, by setting a reluctance modulation structure on the stator core 32, locally changes the air gap magnetic permeability distribution between the permanent magnet rotor 21 and the stator core 32, forming an asymmetrical air gap magnetic field. Without significantly increasing the motor volume or losses, it effectively generates controllable cogging torque. It retains the advantages of high efficiency and low inertia of traditional hollow cup motors, and solves the technical problem that the rotor assembly of the hollow cup motor cannot self-position after power failure. It significantly improves the applicability of the hollow cup motor in scenarios requiring position holding or reverse resistance. Furthermore, by optimizing the air gap magnetic permeability distribution, the reluctance modulation structure can also precisely adjust the magnitude of the cogging torque and the positioning angle, taking into account both the dynamic performance and static positioning requirements of the hollow cup motor.

[0070] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hollow cup motor, characterized in that, The hollow cup motor includes: Housing assembly (10); The rotor assembly and stator assembly, wherein the rotor assembly includes a permanent magnet rotor (21) which is rotatably disposed within the housing assembly (10), and the stator assembly includes a stator spool and a stator core (32), wherein the stator spool is coaxially sleeved on the outside of the permanent magnet rotor (21), and the stator core (32) is coaxially sleeved on the outside of the stator spool; The stator core (32) is provided with a magnetic reluctance modulation structure. The magnetic reluctance modulation structure is used to locally change the air gap magnetic permeability distribution between the permanent magnet rotor (21) and the stator core (32), and to make the air gap between the permanent magnet rotor (21) and the stator core (32) asymmetrically distributed, so that the hollow cup motor can generate cogging torque.

2. The hollow cup motor according to claim 1, characterized in that, The magnetoresistive modulation structure includes at least one first groove (3211), which is disposed on the inner sidewall of the stator core (32) near the permanent magnet rotor (21); And / or, the magnetoresistive modulation structure includes at least one second groove (3212), the second groove (3212) being disposed on the outer side wall of the stator core (32) opposite to the permanent magnet rotor (21); And / or, the magnetoresistive modulation structure includes at least one modulation hole (3213), the modulation hole (3213) being disposed in the stator core (32) and located between the inner sidewall and the outer sidewall of the stator core (32).

3. The hollow cup motor according to claim 2, characterized in that, The number of the first grooves (3211) is multiple, and the multiple first grooves (3211) are arranged at intervals along the circumference of the stator core (32); And / or, the number of the second grooves (3212) is multiple, and the multiple second grooves (3212) are arranged at intervals along the circumference of the stator core (32); And / or, the number of modulation holes (3213) is multiple, and the multiple modulation holes (3213) are arranged at intervals along the circumference of the stator core (32).

4. The hollow cup motor according to claim 3, characterized in that, The number of the first grooves (3211) is multiple, and the multiple first grooves (3211) are equally spaced along the circumference of the stator core (32); And / or, the number of the second grooves (3212) is multiple, and the multiple second grooves (3212) are equally spaced along the circumference of the stator core (32); And / or, the number of modulation holes (3213) is multiple, and the multiple modulation holes (3213) are equally spaced along the circumference of the stator core (32).

5. The hollow cup motor according to claim 2, characterized in that, The magnetoresistive modulation structure includes the first groove (3211), and the extension direction of the first groove (3211) is parallel to the axial direction of the stator core (32). And / or, the magnetoresistive modulation structure includes the second groove (3212), the extension direction of the second groove (3212) being parallel to the axial direction of the stator core (32); And / or, the magnetoresistive modulation structure includes the modulation hole (3213), the extension direction of which is parallel to the axial direction of the stator core (32).

6. The hollow cup motor according to claim 5, characterized in that, The first groove (3211) connects the two opposite sides of the stator core (32) in the axial direction; And / or, the second groove (3212) connects the opposite sides of the stator core (32) in the axial direction; And / or, the modulation hole (3213) connects the opposite sides of the stator core (32) in the axial direction.

7. The hollow cup motor according to claim 5, characterized in that, The first groove (3211) has a cross-sectional profile perpendicular to the extension direction consisting of at least one arc, or at least two straight line segments, or a combination of at least one straight line segment and at least one arc segment. And / or, the cross-sectional profile of the second groove (3212) perpendicular to the extension direction is formed by at least one arc, or by at least two straight segments, or by a combination of at least one straight segment and at least one arc segment; And / or, the modulation aperture (3213) has a circular cross-sectional profile perpendicular to the extension direction, or a polygon formed by at least three straight line segments, or a closed profile formed by a combination of at least one straight line segment and at least one arc segment.

8. The hollow cup motor according to any one of claims 1 to 7, characterized in that, The housing assembly (10) includes a housing (11) and an end cap (12). The end cap (12) is installed on the housing (11). A receiving cavity is formed between the end cap (12) and the housing (11). The permanent magnet rotor (21) and the stator assembly are both located in the receiving cavity.

9. The hollow cup motor according to claim 8, characterized in that, The rotor assembly also includes a first bearing and a second bearing. The first end of the permanent magnet rotor (21) is rotatably connected to the housing (11) through the first bearing, and the second end of the permanent magnet rotor (21) is rotatably connected to the end cover (12) through the second bearing. The first bearing and the second bearing are coaxially arranged.

10. The hollow cup motor according to claim 8, characterized in that, The hollow cup motor also includes a temperature detection component, which is disposed on the end cover (12). The temperature detection component has a sensing part that contacts the side of the stator assembly near the end cover (12).

Images