Multi-layer pole spherical motor with improved torque density

Abstract

The application belongs to the field of multi-degree-of-freedom motors, and particularly relates to a multi-layer magnetic pole spherical motor with improved torque density, which comprises an outer rotor, a stator and an inner rotor. The outer rotor comprises an outer rotor spherical surface and an outer layer of permanent magnets. The stator comprises a stator spherical surface, an electromagnetic coil and a stator base. The inner rotor comprises an inner rotor spherical surface, an inner layer of permanent magnets and a spherical joint bearing. The inner rotor spherical surface and the spherical joint bearing are connected through a middle platform. The middle platform and the outer rotor spherical surface are connected through a connecting shaft. The stator base and the spherical joint bearing are fixedly connected through a rotor support shaft. The spherical centers of the outer rotor spherical surface, the stator spherical surface and the inner rotor spherical surface are the same, the diameter of the inner rotor spherical surface is smaller than that of the stator spherical surface, and the diameter of the stator spherical surface is smaller than that of the outer rotor spherical surface, thereby solving the technical problem of small torque density of the prior art spherical motor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of multi-degree-of-freedom motors, and more particularly relates to a multi-layer magnetic pole spherical motor with improved torque density. BACKGROUND

[0002] As a cutting-edge motor technology, spherical motors exhibit numerous significant advantages due to their unique structural design. They can achieve complex motion with multiple degrees of freedom through a single motor, offering compact structure, flexible motion, high control precision, direct drive at the end, rapid response, small rotational inertia, and low idle load. These characteristics make them have broad application prospects in robotics, manufacturing, aerospace, medical devices, and other fields. However, there are still some challenges to be addressed in spherical motors. Spherical motors with cores can provide larger output torque, but real-time calculation of cogging torque is difficult, leading to difficult control and low control precision. In addition, the saturation characteristics of ferromagnetic materials make the relationship between torque and current nonlinear, and the non-lamination design of the core leads to large eddy current loss. Spherical motors without cores can achieve high control precision, but the output torque is relatively limited. For high load requirements, how to improve the output torque of spherical motors without cores is a key problem that needs to be solved.

[0003] Therefore, developing a new type of spherical motor with high torque density while maintaining high control precision is of great significance for promoting technological progress in related fields. Such a motor will better meet the application needs of related fields and provide strong support for achieving more efficient and accurate automation solutions. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a multi-layer magnetic pole spherical motor with improved torque density, thereby solving the technical problem of small torque density of the prior art spherical motor.

[0005] To achieve the above-mentioned purpose, according to one aspect of the present application, a magnetic pole spherical motor with improved torque density is provided, comprising an outer rotor, a stator, and an inner rotor; the outer rotor comprises an outer rotor spherical surface and an outer layer of permanent magnets; a plurality of outer layer permanent magnets are arranged on the outer rotor spherical surface;

[0006] The stator comprises a stator spherical surface, electromagnetic coils, and a stator base; a plurality of electromagnetic coils are arranged on the stator spherical surface; the stator spherical surface is connected to the stator base;

[0007] The inner rotor comprises an inner rotor spherical surface, inner layer permanent magnets, and a spherical joint bearing; the inner rotor spherical surface is provided with a plurality of inner layer permanent magnets; the inner rotor spherical surface and the spherical joint bearing are connected through a middle platform; the middle platform and the outer rotor spherical surface are connected through a connecting shaft; the stator base and the spherical joint bearing are fixedly connected through a rotor support shaft; the centers of the outer rotor spherical surface, the stator spherical surface, and the inner rotor spherical surface are at the same position, and the diameter of the inner rotor spherical surface is smaller than that of the stator spherical surface, and the diameter of the stator spherical surface is smaller than that of the outer rotor spherical surface.

[0008] Preferably, the spherical joint bearing comprises a bearing base, a bearing output shaft, and a plurality of rolling balls; the bearing base and the bearing output shaft are in sliding contact through the rolling balls; the bearing base is fixedly connected with the middle platform; and the bearing output shaft is fixedly connected with the rotor support shaft.

[0009] Preferably, the distance between the outer layer permanent magnets and the electromagnetic coils is equal to the distance between the electromagnetic coils and the inner layer permanent magnets.

[0010] Preferably, the electromagnetic coils are arrayed and staggered on the stator spherical surface; the electromagnetic coils at the same latitude on the stator spherical surface are uniformly distributed in a circle, and the tangent lines of the upper and lower adjacent electromagnetic coils are equal.

[0011] Preferably, the outer layer permanent magnets are arrayed on the outer rotor spherical surface; the upper and lower adjacent outer layer permanent magnets are distributed at the same longitude, and the tangent lines of the outer layer permanent magnets at the same latitude on the outer rotor spherical surface are equal.

[0012] Preferably, the inner layer permanent magnets are arrayed on the inner rotor spherical surface; the upper and lower adjacent inner layer permanent magnets are distributed at the same longitude, and the tangent lines of the inner layer permanent magnets at the same latitude on the inner rotor spherical surface are equal. The center line of the outer layer permanent magnets and the inner layer permanent magnets passes through the center of the spherical center, and the magnetization directions of the outer layer permanent magnets and the inner layer permanent magnets on the same center line are the same.

[0013] Preferably, the outer layer permanent magnets on the outer rotor spherical surface are symmetric about the center of the spherical center, and the distance between each outer layer permanent magnet and the spherical center is equal.

[0014] Preferably, the electromagnetic coils on the stator spherical surface are symmetric about the center of the spherical center, and the distance between each electromagnetic coil and the spherical center is equal.

[0015] Preferably, the inner layer permanent magnets on the inner rotor spherical surface are centrally symmetric about the spherical center, and each of the inner layer permanent magnets is equidistant from the spherical center. Preferably, the magnetization directions of the outer layer permanent magnets which are centrally symmetric about the spherical center are the same; the magnetization directions of the inner layer permanent magnets which are centrally symmetric about the spherical center are the same; on the outer rotor spherical surface, the magnetization directions of adjacent outer layer permanent magnets are opposite; on the inner rotor spherical surface, the magnetization directions of adjacent inner layer permanent magnets are opposite.

[0016] Preferably, the electromagnetic coils which are centrally symmetric about the spherical center are connected in series and generate magnetic fields with the same direction.

[0017] The present application adopts the nested electromagnetic structure of outer layer permanent magnet-electromagnetic coil-inner layer permanent magnet, and the principle of the electromagnetic structure for enhancing the torque lies in that the scalar magnetic potential generated by the permanent magnets extends from the lower surface of the outer layer permanent magnet to the upper surface of the inner layer permanent magnet, and experiences a jump from a positive maximum value to a negative maximum value in the limited space where the electromagnetic coil is located, and has a higher magnetic potential gradient. The magnetic field intensity is the negative gradient of the magnetic potential, and therefore a higher magnetic potential gradient means a greater magnetic field intensity, and a greater magnetic field intensity means a greater magnetic flux density, so as to enhance the force of the intermediate energized coil layer. The nested electromagnetic structure extending from the outside to the inside ensures that the volume of the motor does not change, and finally achieves the goal of enhancing the torque density.

[0018] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects.

[0019] (1) Compared with the single-layer electromagnetic coil single-layer permanent magnet structure, the multi-layer magnetic pole spherical motor formed by the outer rotor, the stator and the inner rotor has the characteristics of higher magnetic potential gradient and more uniform magnetic field distribution, and the scalar magnetic potential generated by the permanent magnets gradually decays from the maximum value to zero when extending from the surface to infinity, and has the characteristics of high torque density. Compared with the spherical motor with a core, the present application has the advantages of simple torque driving model, no cogging torque, linear relationship between torque and current, and high control accuracy. The permanent magnets in the outer layer and the permanent magnets in the inner layer have high magnetic potential gradient in their adjacent space, provide high-strength local magnetic field, and the electromagnetic coil simultaneously cuts high-density magnetic induction lines, thereby generating enhanced electromagnetic torque in a unit volume.

[0020] (2) The present application limits the distribution mode of the electromagnetic coils which are arrayed and staggered on the spherical surface,

[0021] The purpose is to achieve maximum space utilization, thereby generating higher current density in a limited space, thereby improving the torque density; the present application limits the arrayed distribution mode of the inner layer permanent magnets and the outer layer permanent magnets on the spherical surface, and the purpose is to achieve maximum space utilization, thereby generating higher magnetic field density in a limited space, thereby improving the torque density.

[0022] (3) The present application limits the magnetic field directions of the outer layer permanent magnets and the inner layer permanent magnets on the same center line to be the same, aiming to realize the same direction electromagnetic torque generated by the outer rotor and the inner rotor relative to the stator, so as to improve the torque density; the present application limits the magnetic field directions of the outer layer permanent magnets relative to the center of the sphere to be the same, the magnetic field directions of the inner layer permanent magnets relative to the center of the sphere to be the same, and the magnetic field directions of the electromagnetic coils relative to the center of the sphere to be the same, aiming to realize the same direction electromagnetic torque generated by the two sides relative to the center of the sphere, so as to improve the torque density. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the cross-sectional view of the multi-layer magnetic pole spherical motor provided by the embodiment 1 of the present application.

[0024] Figure 2 is the schematic diagram of the outer shape of the multi-layer magnetic pole spherical motor provided by the embodiment 1 of the present application.

[0025] Figure 3 is the schematic diagram of the electromagnetic system distribution of the multi-layer magnetic pole spherical motor provided by the embodiment 1 of the present application.

[0026] Figure 4 is the schematic diagram of the adjacent and center of the sphere symmetry magnetic field direction of the electromagnetic system of the multi-layer magnetic pole spherical motor provided by the embodiment 1 of the present application.

[0027] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0028] 1, outer rotor; 2, stator; 3, inner rotor; 11, outer rotor spherical surface; 12, outer layer permanent magnet; 21, stator spherical surface; 22, electromagnetic coil; 23, stator base; 31, inner rotor spherical surface, 32, inner layer permanent magnet, 4, spherical joint bearing; 5, middle platform; 6, connecting shaft; 7, rotor support shaft; 41, bearing base; 42, bearing output shaft; 43, ball. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] Embodiment 1

[0031] Figure 1The application discloses a multi-layer magnetic pole spherical motor.

[0032] The stator 2 comprises a stator spherical surface 21, electromagnetic coils 22 and a stator base 23; a plurality of the electromagnetic coils 22 are arranged on the outer surface of the stator spherical surface 21; the stator spherical surface 21 is connected with the stator base 23.

[0033] The inner rotor 3 comprises an inner rotor spherical surface 31, inner layer permanent magnets 32 and a spherical joint bearing 4; a plurality of the inner layer permanent magnets 32 are arranged on the outer surface of the inner rotor spherical surface 31; the inner rotor spherical surface 31 is connected with the spherical joint bearing 4 through a middle platform 5; the middle platform 5 is connected with the outer rotor spherical surface 11 through a connecting shaft 6; the stator base 23 is fixedly connected with the spherical joint bearing 4 through a rotor support shaft 7, so that synchronous movement of the inner and outer rotors is realized.

[0034] The spherical centers of the outer rotor spherical surface 11, the stator spherical surface 21 and the inner rotor spherical surface 31 are the same, the diameter of the inner rotor spherical surface 31 is smaller than that of the stator spherical surface 21, and the diameter of the stator spherical surface 21 is smaller than that of the outer rotor spherical surface 11. The outer rotor 1, the stator 2 and the inner rotor 3 have a spherical shape in the electromagnetic distribution part, so that the mass and the rotational inertia of the multi-layer magnetic pole spherical motor can be reduced to the maximum. The stator 2 is arranged between the outer rotor 1 and the inner rotor 3, the air gap thickness between the outer layer permanent magnets 12 and the electromagnetic coils 22 is consistent with the air gap thickness between the electromagnetic coils 22 and the inner layer permanent magnets 32.

[0035] The spherical joint bearing comprises a bearing base 41, a bearing output shaft 42 and rolling balls 43, is used for connecting the stator 2 and the inner rotor 3, the bearing base 41 is fixedly connected with the middle platform, the bearing output shaft 42 is fixedly connected with the rotor support shaft 7, the rolling balls 43 are embedded between the bearing base 4 and the bearing output shaft 5 through a retainer, so that the joint ball at the end of the bearing output shaft 42 rotates through rolling friction.

[0036] Figure 2 The application discloses a multi-layer magnetic pole spherical motor. Figure 2As shown, the outer rotor 1 is composed of two symmetrical hemispherical parts to facilitate the assembly of the stator 2 and the inner rotor 3, and the two hemispherical parts are respectively connected with the connecting shaft 6 of the inner rotor 3 through screw connection; the stator 2 is composed of two symmetrical parts to facilitate the assembly of the inner rotor 3, and the stator base 23 of the stator is connected with the bottom of the rotor support shaft 7 through screw connection; the inner rotor 3 is an integral body, and the middle platform 5 is connected with the ball joint bearing base 41 through screw connection; the bearing output shaft 42 is connected with the rotor support shaft 7 through screw connection and is positioned through a pin shaft, so as to ensure the connection reliability of the stator and the inner rotor; the bottom of the rotor support shaft 7 and the stator base 23 are both provided with a groove to facilitate the wiring of the electromagnetic coil 22, and the final wiring position is the bottom of the stator base 23; in actual application, the outer rotor 1 is usually used as the connection part of the multi-layer magnetic pole spherical motor and the end effector, and the stator base 23 of the stator 2 is usually used as the connection part of the multi-layer magnetic pole spherical motor and the work platform.

[0037] Figure 3 The specific arrangement mode of the coil 22, the outer layer permanent magnet 12 and the inner layer permanent magnet 32 is as follows: a plurality of electromagnetic coils 22 are arranged in an array and staggered on the stator spherical surface 21, and are arranged in three circles from top to bottom on the stator spherical surface 21, and each circle is uniformly distributed in the circumference, and the upper and lower circles are arranged on the same longitude, and the middle circle is staggered with the upper and lower circles, and the side surfaces of the adjacent electromagnetic coils 22 of the upper and lower circles are tangent to each other, so as to realize the maximum space utilization and generate higher current density in the limited space; the outer layer permanent magnets 12 are arranged in two upper and lower circles in an array on the outer rotor spherical surface 11, and the adjacent outer layer permanent magnets 12 in each circle are uniformly distributed and arranged on the same longitude, and the side surfaces of the adjacent outer layer permanent magnets 12 in the same circle are tangent to each other; the inner layer permanent magnets 32 are arranged in two upper and lower circles in an array on the inner rotor spherical surface 31, and the adjacent inner layer permanent magnets 32 in each circle are uniformly distributed and arranged on the same longitude, and the side surfaces of the adjacent inner layer permanent magnets 32 in the same circle are tangent to each other, so as to realize the maximum space utilization and generate higher density magnetic field in the limited space.

[0038] Figure 4 It is a schematic diagram of the adjacent and central symmetrical magnetic field directions of the electromagnetic system of the multi-layer magnetic pole spherical motor, as shown in the figure, Figure 4As shown, the electromagnetic system comprises outer layer permanent magnets 12, electromagnetic coils 22, inner layer permanent magnets 32; in the electromagnetic system design space, the axes of the electromagnetic coils 22, the outer layer permanent magnets 12 and the inner layer permanent magnets 32 all pass through the rotation center, the distribution is symmetrical about the spherical center, the distances of different electromagnetic coils 22 in the same layer to the spherical center are equal, the distances of different outer layer permanent magnets 12 in the same layer to the spherical center are equal, and the distances of the inner layer permanent magnets 32 in the same layer to the spherical center are equal; the magnetization directions of the outer layer permanent magnets (12) symmetrical about the spherical center are the same (i.e. the magnetization directions of the two outer layer permanent magnets 12 symmetrical about the spherical center, one magnetization direction points to the spherical center, and the other magnetization direction departs from the spherical center), the magnetization directions of the two inner layer permanent magnets 32 symmetrical about the spherical center are the same (i.e. the magnetization directions of the two inner layer permanent magnets 32 symmetrical about the spherical center, one magnetization direction points to the spherical center, and the other magnetization direction departs from the spherical center); the center line of the outer layer permanent magnets 12 and the inner layer permanent magnets 32 passes through the spherical center, and the magnetization directions of the outer layer permanent magnets 12 and the inner layer permanent magnets 32 on the same center line are the same; the magnetization directions of the adjacent outer layer permanent magnets 12 in the same layer are opposite, and the magnetization directions of the adjacent inner layer permanent magnets 32 in the same layer are opposite; the electromagnetic coils 22 symmetrical about the spherical center are connected in series, and the magnetic field directions generated thereby are the same (i.e. the magnetic field directions of the two electromagnetic coils 22 symmetrical about the spherical center, one magnetic field direction points to the spherical center, and the other magnetic field direction departs from the spherical center). The current passing through the electromagnetic coils 22 is determined according to the posture of the motor and the expected torque command, so as to generate electromagnetic torques in the same direction on both sides of the spherical center; the center line of the electromagnetic coils 22 and the spherical center is the first axis, and the center line of the outer layer permanent magnets 12 and the inner layer permanent magnets 32 passing through the spherical center is the second axis, in the initial position, the first axis and the second axis do not coincide, so as to avoid the excessive drive current required when the multi-layer magnetic pole spherical motor starts in the initial position.

[0039] In operation, by passing current through the electromagnetic coils 22, electromagnetic interaction is generated between the coils and the outer layer permanent magnets 12 and the inner layer permanent magnets 32, so as to realize the spatial three-degree-of-freedom motion of the rotor part relative to the stator part.

[0040] It is to be understood that the above-described embodiments are merely exemplary of the application and that various modifications, equivalent substitutions and improvements can be made thereto without departing from the spirit and scope of the application.

Claims

1. A magnetic pole spherical motor with improved torque density, characterized in that, It includes an outer rotor (1), a stator (2) and an inner rotor (3); the outer rotor (1) includes an outer rotor spherical surface (11) and an outer permanent magnet (12); a plurality of outer permanent magnets (12) are disposed on the outer rotor spherical surface (11); The stator (2) includes a stator spherical surface (21), an electromagnetic coil (22), and a stator base (23); a plurality of electromagnetic coils (22) are disposed on the stator spherical surface (21); the stator spherical surface (21) is connected to the stator base (23); The inner rotor (3) includes an inner rotor spherical surface (31), an inner permanent magnet (32), and a ball joint bearing (4); a plurality of the inner permanent magnets (32) are arranged on the inner rotor spherical surface (31); the inner rotor spherical surface (31) and the ball joint bearing (4) are connected by a central platform (5); the central platform (5) and the outer rotor spherical surface (11) are connected by a connecting shaft (6); the stator base (23) and the ball joint bearing (4) are fixedly connected by a rotor support shaft (7); the outer rotor spherical surface (11), the stator spherical surface (21), and the inner rotor spherical surface The centers of the balls (31) are in the same position, and the diameter of the inner rotor spherical surface (31) is smaller than the diameter of the stator spherical surface (21), and the diameter of the stator spherical surface (21) is smaller than the diameter of the outer rotor spherical surface (11); the ball joint bearing (4) includes a bearing base (41), a bearing output shaft (42) and balls (43); the bearing base (41) and the bearing output shaft (42) are in sliding contact through a plurality of balls (43); the bearing base (41) is fixedly connected to the central platform; the bearing output shaft (42) is fixedly connected to the rotor support shaft (7).

2. The magnetic pole spherical motor with improved torque density as described in claim 1, characterized in that, The distance between the outer permanent magnet (12) and the electromagnetic coil (22) is equal to the distance between the electromagnetic coil (22) and the inner permanent magnet (32).

3. A magnetic pole spherical motor with improved torque density as described in claim 1, characterized in that, The electromagnetic coils (22) are arranged in an array on the stator spherical surface (21); the electromagnetic coils (22) at the same latitude on the stator spherical surface (21) are evenly distributed on the circumference, and the upper and lower adjacent electromagnetic coils (22) are tangent to each other.

4. A magnetic pole spherical motor with improved torque density as described in claim 1, characterized in that, The outer permanent magnets (12) are arranged in an array on the outer rotor spherical surface (11). The upper and lower adjacent outer permanent magnets (12) are spaced apart and located at the same longitude. The outer permanent magnets (12) at the same latitude on the outer rotor spherical surface (11) are tangent to each other on the sides.

5. A magnetic pole spherical motor with improved torque density as described in claim 4, characterized in that, The inner permanent magnets (32) are arranged in an array on the inner rotor spherical surface (31). The upper and lower adjacent inner permanent magnets (32) are spaced apart and located at the same longitude. The inner permanent magnets (32) at the same latitude on the inner rotor spherical surface (31) are tangent to each other on the sides. The center line connecting the outer permanent magnet (12) and the center line connecting the inner permanent magnet (32) passes through the center of the sphere. The outer permanent magnets (12) located on the same center line have the same magnetization direction as the inner permanent magnets (32).

6. A magnetic pole spherical motor with improved torque density as described in claim 5, characterized in that, The outer permanent magnets (12) on the outer rotor spherical surface (11) are symmetrical about the center of the sphere, and each of the outer permanent magnets (12) is equidistant from the center of the sphere; The electromagnetic coils (22) on the stator spherical surface (21) are symmetrical about the center of the sphere, and each electromagnetic coil (22) is equidistant from the center of the sphere; The inner permanent magnets (32) on the inner rotor spherical surface (31) are symmetrical about the center of the sphere, and each inner permanent magnet (32) is equidistant from the center of the sphere.

7. A magnetic pole spherical motor with improved torque density as described in claim 6, characterized in that, The outer permanent magnets (12) symmetrical about the center of the sphere have the same magnetization direction; the inner permanent magnets (32) symmetrical about the center of the sphere have the same magnetization direction; the electromagnetic coils (22) symmetrical about the center of the sphere are connected in series and energized, and the magnetic fields they generate have the same direction.

8. A magnetic pole spherical motor with improved torque density as described in claim 7, characterized in that, On the outer rotor spherical surface (11), the magnetization directions of adjacent outer permanent magnets (12) are opposite; on the inner rotor spherical surface (31), the magnetization directions of adjacent inner permanent magnets (32) are opposite.

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