Axial-radial composite flux electromagnetic drive with hollow stator

Abstract

The invention discloses an axial-radial composite magnetic flux electromagnetic drive with a hollow stator, which is characterized in that two radial rotors and two axial rotors respectively form air gap magnetic fields in the radial direction and the axial direction of the stator; the air-gap magnetic field interacts with symmetrical current in a coil winding surrounding the mutually-embedded stator structure to generate output torque and synchronous rotating speed, so that the end winding of the motor is effectively utilized through the design of the four rotors, the air-gap area of the motor for electromechanical energy conversion can be effectively increased while the size of the system is not increased, and the efficiency of the motor is improved. The torque density of the motor is increased; meanwhile, symmetrical air-gap magnetic fields are formed at the two axial ends of the stator by the radial or axial magnetic pole array with alternately magnetized N poles and S poles, so that the radial magnetic flux and the axial magnetic flux are decoupled, the thickness of the stator yoke can be reduced, the stator yoke is even hollow, and the cost and the weight are reduced; in addition, the hollow part of the stator core also provides favorable conditions for arranging a heat dissipation flow channel in the internal space of the motor, so that the torque output capability of the motor is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to axial-radial composite flux electromagnetic drive with a hollow stator. Background Art

[0002] Improving the torque density of motors is an eternal topic for direct drive electromechanical systems (without reducers), such as motors for electric propulsion aircraft propellers, underwater thrusters, etc. Currently, there are mainly three ways to improve torque density: one is to increase the current, but this will cause serious heating, so an additional cooling system is required; the second is to increase the air-gap magnetic flux density through a magnetic pole array, but it is limited by the saturation of silicon steel materials; the third is in the form of a high-speed motor plus a reducer, but the system efficiency is low, and the higher the speed, the larger the reduction ratio and the greater the vibration and noise; the fourth is to improve the reluctance torque through an embedded motor such as a new energy vehicle motor (V-type and spoke-type motors); the fifth is the currently very popular disk motor (also called axial flux motor). The axial flux motor has a large rotor air-gap surface and no stator yoke, so the output torque density is large, but the single flux also results in the underutilization of the stator end windings.

[0003] Currently, permanent magnet synchronous motors can be mainly classified into radial flux motors and axial flux motors according to the magnetic flux. The disadvantages of these two types of motors are summarized as follows:

[0004] 1. Single magnetic flux leads to low space utilization: In traditional single magnetic flux motors, only one or two rotors interact with the stator armature windings to generate output torque, resulting in low space utilization of the motor. For example, the axial space of an outer rotor radial flux motor is wasted, and the radial space of an outer rotor axial flux motor is wasted.

[0005] 2. The end windings of traditional stator coils are long, increasing the system weight: Whether it is a distributed winding or a toroidal winding, there are long end windings that do not interact with the permanent magnetic field to generate torque, and the system weight is increased. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide an axial-radial composite flux electromagnetic drive that can both improve torque density and space utilization.

[0007] To solve the above technical problems, the present invention provides an axial-radial composite flux electromagnetic drive with a hollow stator, which includes a stator and a rotor. The stator includes a stator bracket, a stator core, and a coil winding. The stator bracket is axially opposite to the stator core and is fixedly connected to the stator core by bolts. The stator bracket is fixedly connected with a central shaft. The stator core is annular. The central shaft is inserted axially into the middle of the stator core and is coaxial with the stator core. A plurality of first radial teeth evenly distributed along the circumferential direction are provided on the outer circumference of the stator core. A plurality of second radial teeth evenly distributed along the circumferential direction are provided on the inner circumference of the stator core. A plurality of first axial teeth evenly distributed along the circumferential direction are provided at the front end of the stator core. A plurality of second axial teeth evenly distributed along the circumferential direction are provided at the rear end of the stator core. The coil winding is rectangularly wound around the first radial teeth, the second radial teeth, the first axial teeth, and the second axial teeth. The rotor includes a rotor housing and a first radial magnetic pole array, a second radial magnetic pole array, a first axial magnetic pole array, and a second axial magnetic pole array respectively fixed on the rotor housing. The rotor housing is rotatably connected to the central shaft through bearings. The first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array are all arranged in an annular shape. The first radial magnetic pole array is spaced opposite to the first radial teeth to form a first radial air gap. The second radial magnetic pole array is spaced opposite to the second radial teeth to form a second radial air gap. The first axial magnetic pole array is spaced opposite to the first axial teeth to form a first axial air gap. The second axial magnetic pole array is spaced opposite to the second axial teeth to form a second axial air gap. The pole pitches of the first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array are the same and all the permanent magnets are aligned. Pole pitch: τ = 360° / 2P, where p is the number of pole pairs. The first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array are all based on the center line of the permanent magnets corresponding to the same central angle and with the magnetization direction towards or away from the air gap. The magnetization direction of the permanent magnets changes alternately between away from the air gap and towards the air gap every pole pitch. The first radial teeth, the second radial teeth, the first axial teeth, and the second axial teeth are all provided with tooth parts, yoke parts connected to one end of the tooth parts, and pole shoes connected to the other end of the tooth parts. The yoke parts of the first radial teeth, the yoke parts of the second radial teeth, the yoke parts of the first axial teeth, and the yoke parts of the second axial teeth enclose a hollow chamber with a rectangular axial cross-section.

[0008] As a preferred embodiment of the present invention, the yoke portions of the first radial teeth and the yoke portions of the second radial teeth are connected by a web plate and form an integral radial tooth; the first axial tooth is fixed to the front end of the integral radial tooth by welding or screws or adhesives, and the second axial tooth is fixed to the rear end of the integral radial tooth by welding or screws or adhesives.

[0009] As a preferred embodiment of the present invention, a plurality of web plates are evenly distributed in the circumferential direction, and the plurality of web plates divide the hollow chamber into a plurality of chamber units; aluminum blocks are embedded in the chamber units.

[0010] As a preferred embodiment of the present invention, first groove edges that cooperate with the outer periphery of the yoke portion of the first axial tooth or the second axial tooth are respectively provided at both axial ends of the yoke portion of the first radial tooth, and the groove depth of the first groove edge is the same as the thickness of the outer periphery of the yoke portion of the first axial tooth or the second axial tooth; second groove edges that cooperate with the inner periphery of the yoke portion of the first axial tooth or the second axial tooth are respectively provided at both axial ends of the yoke portion of the second radial tooth, and the groove depth of the second groove edge is the same as the thickness of the inner periphery of the yoke portion of the first axial tooth or the second axial tooth.

[0011] As a preferred embodiment of the present invention, the tooth profile of the tooth portion of the first radial tooth in the radial cross-section is rectangular, and the tooth groove formed between two adjacent first radial teeth is a trapezoidal groove; the tooth profile of the tooth portion of the second radial tooth in the radial cross-section is rectangular, and the tooth groove formed between two adjacent second radial teeth is a trapezoidal groove; the tooth profile of the tooth portion of the first axial tooth in the radial cross-section is trapezoidal, and the tooth groove formed between two adjacent first axial teeth is a parallel groove; the tooth profile of the tooth portion of the second axial tooth in the radial cross-section is trapezoidal, and the tooth groove formed between two adjacent second axial teeth is a parallel groove.

[0012] As a preferred embodiment of the present invention, the rotor housing is provided with a rotating housing, a rotating shaft sleeve, a front cover plate and a rear cover plate. The front end of the rotating housing is fixedly connected to the front cover plate. The rotating shaft sleeve is rotatably connected to the central shaft through a bearing. The front end of the rotating shaft sleeve is fixedly connected to the front cover plate, and the rear end of the rotating shaft sleeve is fixedly connected to the rear cover plate. The rear cover plate is disposed between the stator bracket and the stator core; the first radial magnetic pole array is fixedly arranged on the inner circumference of the rotating housing, the second radial magnetic pole array is fixedly arranged on the outer circumference of the rotating shaft sleeve, the first axial magnetic pole array is fixedly arranged on the inner side of the front cover plate, and the second axial magnetic pole array is fixedly arranged on the inner side of the rear cover plate.

[0013] As a preferred embodiment of the present invention, a first embedding groove for accommodating and fixing the first axial magnetic pole array is provided on the inner side of the front cover plate. A first back iron is provided on the bottom surface side of the first axial magnetic pole array facing the first embedding groove, and the thickness of the first back iron gradually increases from the inner diameter to the outer diameter side of the front cover plate. A second embedding groove for accommodating and fixing the second axial magnetic pole array is provided on the inner side of the rear cover plate. A second back iron is provided on the bottom surface side of the second axial magnetic pole array facing the second embedding groove, and the thickness of the second back iron gradually increases from the inner diameter to the outer diameter side of the rear cover plate.

[0014] As a preferred embodiment of the present invention, at least one transition permanent magnet is provided in each pole pitch of the first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array. The radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array are all based on the center line of the permanent magnets corresponding to the same central angle and having magnetization directions all facing the air gap or departing from the air gap. The magnetization directions of the respective transition permanent magnets in each pole pitch gradually change to depart from the air gap or face the air gap in the clockwise or counterclockwise direction.

[0015] As a preferred embodiment of the present invention, the first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array are all Halbach magnetic pole arrays.

[0016] As a preferred embodiment of the present invention, an output shaft coaxial with the central axis is installed on the outer side of the front cover plate.

[0017] Implementing the axial-radial composite flux electromagnetic drive with a hollow stator of the embodiments of the present invention has the following beneficial effects compared with the prior art:

[0018] First, the first radial rotor (i.e., the first radial magnetic pole array), the second radial rotor (i.e., the second radial magnetic pole array), the first axial rotor (i.e., the first axial magnetic pole array), and the second axial rotor (i.e., the second axial magnetic pole array) respectively form an air gap magnetic field in the radial and axial directions of the stator. When three-phase sinusoidal current excitations with a 120-degree electrical angle difference are applied to the coil windings wound around the first radial teeth, the second radial teeth, the first axial teeth, and the second axial teeth, the air gap magnetic field formed by the rotor interacts with the symmetric current in the coil windings to generate a rotating magnetomotive force, driving the first radial rotor, the second radial rotor, the first axial rotor, and the second axial rotor to rotate synchronously to output power and torque. This design of four rotors effectively utilizes the coil windings at the ends of the motor. Without increasing the system volume, it can effectively increase the air gap area of the motor for electromechanical energy conversion (generating torque), thereby increasing the torque density of the motor, and will not cause waste of axial or radial space, improving the space utilization rate of the motor.

[0019] Secondly, the magnetic field lines generated by the first radial magnetic pole array pass through the coil windings wound around the first radial teeth to form a first radial magnetic flux, and the magnetic field lines generated by the second radial magnetic pole array pass through the coil windings wound around the second radial teeth to form a second radial magnetic flux. The magnetic field lines generated by the first axial magnetic pole array pass through the coil windings wound around the first axial teeth to form a first axial magnetic flux, and the magnetic field lines generated by the second axial magnetic pole array pass through the coil windings wound around the second axial teeth to form a second axial magnetic flux. Thus, the first radial magnetic flux, the second radial magnetic flux, the first axial magnetic flux, and the second axial magnetic flux constitute a three-dimensional magnetic flux. At the same time, due to the first radial magnetic pole array and the second radial magnetic pole array magnetized alternately with N poles and S poles, symmetric air-gap magnetic fields are formed on the two radial sides of the stator, and the first axial magnetic pole array and the second axial magnetic pole array magnetized alternately with N poles and S poles form symmetric air-gap magnetic fields at the two axial ends of the stator. This means that the radial magnetic flux and the axial magnetic flux do not cross each other in the stator yoke, enabling the decoupling of the radial magnetic flux and the axial magnetic flux, thereby realizing the decoupling of the three-dimensional magnetic flux. It is possible to reduce the thickness of the stator yoke, or even make it hollow, reducing the use of materials, thus reducing costs and weight. In addition, the hollow part of the stator core also provides favorable conditions for setting up heat dissipation channels in the internal space of the motor to further improve the torque output capacity of the motor.

[0020] Finally, the coil windings are wound around the first radial teeth, the second radial teeth, the first axial teeth, and the second axial teeth in a rectangular shape, enabling the four sides of the coil windings to interact with the radial magnetic flux and the axial magnetic flux generated by the magnetic pole array to generate an output torque. That is to say, the coil windings only form end windings (i.e., the winding parts that do not interact with the permanent magnet magnetic field to generate torque) when the wire crosses the position adjacent to the tooth grooves, which can greatly reduce the length of the end windings of the stator coil, reduce the stator weight and winding copper loss. And the end windings of the stator coil do not increase with the increase of the axial length of the motor, ensuring the utilization rate of the coil windings. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below.

[0022] Figure 1 is an axonometric view of the axial-radial composite flux electromagnetic drive with a hollow stator according to an embodiment of the present invention;

[0023] Figure 2 is a front view of the axial-radial composite flux electromagnetic drive with a hollow stator according to an embodiment of the present invention;

[0024] Figure 3 is at Figure 2 the cross-sectional view taken along the line A-A of the structure shown;

[0025] Figure 4 Exploded view of the axial-radial composite flux electromagnetic drive with a hollow stator according to an embodiment of the present invention;

[0026] Figure 5 Connection structure diagram of the stator core and the coil winding;

[0027] Figure 6 Exploded view of the stator core and the coil winding;

[0028] Figure 7 Arrangement schematic diagram of the magnetization directions of the permanent magnets in the first radial pole array, the second radial pole array, the first axial pole array or the second axial pole array;

[0029] Figure 8 Output torque waveform diagrams of the axial-radial composite flux electromagnetic drive, the double-rotor radial flux electromagnetic drive and the double-rotor axial flux electromagnetic drive;

[0030] Figure 9 Magnetic flux density distribution nephogram of the axial pole array of the equal-thickness back iron;

[0031] Figure 10 Magnetic flux density distribution nephogram of the axial pole array of the unequal-thickness back iron;

[0032] Figure 11 Output torque comparison diagram of the disc motor with the axial pole array of the equal-thickness back iron and the disc motor with the axial pole array of the unequal-thickness back iron.

[0033] Markings in the figure:

[0034] Stator 1; Stator bracket 11; Stator core 12; Coil winding 13; Central shaft 14; First radial tooth 15; Second radial tooth 16; First axial tooth 17; Second axial tooth 18; Hollow chamber 19; Aluminum block 110; Web 111; First slot edge 112; Second slot edge 113; Tooth part a; Yoke part b; Pole shoe c;

[0035] Rotor 2; Rotor housing 21; Rotating shell 211; Rotating shaft sleeve 212; Front cover plate 213; Rear cover plate 214; First embedding groove 215; Second embedding groove 216; First radial pole array 22; Second radial pole array 23; First axial pole array 24; Second axial pole array 25; Bearing 26; First back iron 27; Second back iron 28;

[0036] Output shaft 3. Detailed implementation manners

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. in the present invention is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] As Figures 1 to 7 shown, a preferred embodiment of the present invention.

[0040] Axial-radial composite flux electromagnetic drive with a hollow stator, which includes a stator 1 and a rotor 2.

[0041] The stator 1 includes a stator bracket 11, a stator core 12, and a coil winding 13; the stator bracket 11 is axially opposite to the stator core 12 and is fixedly connected to the stator core 12 by bolts; the stator bracket 11 is fixedly connected with a central shaft 14, the stator core 12 is in a circular ring shape, the central shaft 14 is axially inserted into the middle of the stator core 12 and is coaxial with the stator core 12; a plurality of first radial teeth 15 evenly distributed along the circumferential direction are provided on the outer periphery of the stator core 12, a plurality of second radial teeth 16 evenly distributed along the circumferential direction are provided on the inner periphery of the stator core 12, a plurality of first axial teeth 17 evenly distributed along the circumferential direction are provided at the front end of the stator core 12, and a plurality of second axial teeth 18 evenly distributed along the circumferential direction are provided at the rear end of the stator core 12; the coil winding 13 is rectangularly wound around the first radial teeth 15, the second radial teeth 16, the first axial teeth 17, and the second axial teeth 18.

[0042] The rotor 2 includes a rotor housing 21, and a first radial magnetic pole array 22, a second radial magnetic pole array 23, a first axial magnetic pole array 24, and a second axial magnetic pole array 25 that are respectively fixed on the rotor housing 21; the rotor housing 21 is rotatably connected to the central shaft 14 through a bearing 26; the first radial magnetic pole array 22, the second radial magnetic pole array 23, the first axial magnetic pole array 24, and the second axial magnetic pole array 25 are all arranged in an annular shape, the first radial magnetic pole array 22 and the first radial tooth 15 are spaced apart to form a first radial air gap, the second radial magnetic pole array 23 and the second radial tooth 16 are spaced apart to form a second radial air gap, the first axial magnetic pole array 24 and the first axial tooth 17 are spaced apart to form a first axial air gap, and the second axial magnetic pole array 25 and the second axial tooth 18 are spaced apart to form a second axial air gap; the pole pitches of the first radial magnetic pole array 22, the second radial magnetic pole array 23, the first axial magnetic pole array 24, and the second axial magnetic pole array 25 are the same and each permanent magnet is aligned, pole pitch: τ = 360° / 2P, where p is the number of pole pairs; the first radial magnetic pole array 22, the second radial magnetic pole array 23, the first axial magnetic pole array 24, and the second axial magnetic pole array 25 are all based on the center line of the permanent magnet corresponding to the same central angle and with the magnetization direction facing the air gap or away from the air gap, and the magnetization direction of the permanent magnet changes alternately between facing away from the air gap and facing the air gap every pole pitch.

[0043] For the axial-radial composite flux electromagnetic drive with a hollow stator according to an embodiment of the present invention, it forms an air gap magnetic field in the radial and axial directions of the stator 1 through the first radial rotor (i.e., the first radial magnetic pole array 22), the second radial rotor (i.e., the second radial magnetic pole array 23), the first axial rotor (i.e., the first axial magnetic pole array 24), and the second axial rotor (i.e., the second axial magnetic pole array 25). When three-phase sinusoidal current excitations with a phase difference of 120 electrical degrees are applied to the coil windings 13 wound around the first radial tooth 15, the second radial tooth 16, the first axial tooth 17, and the second axial tooth 18, the air gap magnetic field formed by the rotor 2 interacts with the symmetric current in the coil windings 13 to generate a rotating magnetomotive force, driving the first radial rotor, the second radial rotor, the first axial rotor, and the second axial rotor to rotate synchronously to output force and torque. This design of four rotors effectively utilizes the coil windings 13 at the ends of the motor. Without increasing the system volume, it can effectively increase the air gap area of the motor for electromechanical energy conversion (generating torque), thereby increasing the torque density of the motor, and will not cause waste of axial or radial space, improving the space utilization rate of the motor.

[0044] It should also be noted that the axial-radial composite flux electromagnetic drive with a hollow stator according to an embodiment of the present invention has achieved significant technical progress in the following aspects:

[0045] (1) The magnetic field lines generated by the first radial pole array 22 pass through the coil winding 13 wound around the first radial tooth 15 to form a first radial magnetic flux. The magnetic field lines generated by the second radial pole array 23 pass through the coil winding 13 wound around the second radial tooth 16 to form a second radial magnetic flux. The magnetic field lines generated by the first axial pole array 24 pass through the coil winding 13 wound around the first axial tooth 17 to form a first axial magnetic flux. The magnetic field lines generated by the second axial pole array 25 pass through the coil winding 13 wound around the second axial tooth 18 to form a second axial magnetic flux. Thus, the first radial magnetic flux, the second radial magnetic flux, the first axial magnetic flux, and the second axial magnetic flux constitute a three-dimensional magnetic flux. At the same time, due to the first radial pole array 22 and the second radial pole array 23 magnetized alternately with N and S poles, a symmetric air-gap magnetic field is formed on both radial sides of the stator 1. The first axial pole array 24 and the second axial pole array 25 magnetized alternately with N and S poles form a symmetric air-gap magnetic field at both axial ends of the stator 1. This means that the radial magnetic flux and the axial magnetic flux do not cross each other in the yoke of the stator 1, enabling the decoupling of the radial magnetic flux and the axial magnetic flux, thereby achieving the decoupling of the three-dimensional magnetic flux. It is possible to reduce the thickness of the stator 1 yoke, or even make it hollow, reducing the use of materials, thus reducing costs and weight. In addition, the hollow part of the stator core 12 also provides favorable conditions for setting up a heat dissipation flow channel in the internal space of the motor, so as to further improve the torque output capacity of the motor.

[0046] (2) The coil winding 13 is wound around the first radial tooth 15, the second radial tooth 16, the first axial tooth 17, and the second axial tooth 18 in a rectangular shape, so that the four sides of the coil winding 13 can interact with the radial magnetic flux and the axial magnetic flux generated by the corresponding pole arrays to generate an output torque. That is to say, the coil winding 13 only forms an end winding at the part where the wire crosses the tooth-slot adjacent part (i.e., the winding part that does not interact with the permanent magnet magnetic field to generate torque), which can greatly reduce the length of the end winding of the stator 1 coil, reduce the weight of the stator 1 and the copper loss of the winding. And the end winding of the stator 1 coil does not increase with the increase of the axial length of the motor, ensuring the utilization rate of the coil winding 13.

[0047] As Figure 8 shown, Figure 8 The output torque waveforms of the axial-radial composite magnetic flux electromagnetic drive, the double-rotor radial magnetic flux electromagnetic drive, and the double-rotor axial magnetic flux electromagnetic drive with the same volume are compared. It can be seen from the figure that the axial-radial composite magnetic flux electromagnetic drive has the largest average output torque because it greatly removes the end winding (i.e., the winding part that does not interact with the permanent magnet magnetic field to generate torque) and adds an additional two-layer electromagnetic interaction air-gap, and is 1.95 and 2.06 times that of the double-rotor radial magnetic flux electromagnetic drive and the double-rotor axial magnetic flux electromagnetic drive respectively.

[0048] Furthermore, asFigure 6 As shown, the first radial tooth 15, the second radial tooth 16, the first axial tooth 17, and the second axial tooth 18 are all provided with a tooth portion a, a yoke portion b connected to one end of the tooth portion a, and a pole shoe c connected to the other end of the tooth portion a; the yoke portions b of the first radial tooth 15, the yoke portions b of the second radial tooth 16, the yoke portions b of the first axial tooth 17, and the yoke portions b of the second axial tooth 18 enclose a hollow chamber 19 with a rectangular axial cross-section. Since the radial magnetic flux and the axial magnetic flux are decoupled, the thickness of each yoke portion b can be designed to be smaller, and the volume of the hollow chamber 19 can be made larger, greatly reducing the system weight; in addition, an aluminum block 110 with a low mass density and high thermal conductivity can be embedded in the hollow chamber 19, which can effectively reduce the thermal resistance of the heat conduction path from the inside to the outside and will not significantly increase the mass of the stator 1.

[0049] Exemplarily, the first axial tooth 17 and the second axial tooth 18 are both made of a solid composite soft magnetic material (SMC) or laminated silicon steel sheets, and the first radial tooth 15 and the second radial tooth 16 are both formed by laminating silicon steel sheets.

[0050] Exemplarily, as Figure 6 shown, for the convenience of assembly, the yoke portion b of the first radial tooth 15 and the yoke portion b of the second radial tooth 16 are connected by a web 111 and form an integral radial tooth; the first axial tooth 17 is fixed to the front end of the integral radial tooth by welding or screws or adhesive, and the second axial tooth 18 is fixed to the rear end of the integral radial tooth by welding or screws or adhesive. Further, a plurality of webs 111 are evenly distributed in the circumferential direction, and the plurality of webs divide the hollow chamber 19 into a plurality of chamber units; the aluminum block 110 is embedded in the chamber unit.

[0051] Exemplarily, as Figure 6 shown, first groove edges 112 that cooperate with the outer circumference of the yoke portion b of the first axial tooth 17 or the second axial tooth 18 are respectively provided at both axial ends of the yoke portion b of the first radial tooth 15, and the groove depth of the first groove edge 112 is the same as the outer circumference thickness of the yoke portion b of the first axial tooth 17 or the second axial tooth 18; second groove edges 113 that cooperate with the inner circumference of the yoke portion b of the first axial tooth 17 or the second axial tooth 18 are respectively provided at both axial ends of the yoke portion b of the second radial tooth 16, and the groove depth of the second groove edge 113 is the same as the inner circumference thickness of the yoke portion b of the first axial tooth 17 or the second axial tooth 18. Such a design can further reduce the axial length of the stator 1 and at the same time make the connection structure between the axial tooth and the radial tooth more compact and reliable.

[0052] Exemplarily, as Figure 5 and Figure 6As shown in the figure, in the axial-radial composite flux electromagnetic drive with a hollow stator according to the embodiment of the present invention, the first radial teeth 15, the second radial teeth 16, the first axial teeth 17, and the second axial teeth 18 share a set of coil windings 13. Therefore, the cross-sectional area of the coil windings occupying the tooth slots is the same. When the tooth slots formed by the radial teeth are parallel slots, the tooth parts a of the radial teeth are trapezoidal in the axial projection. However, the radial magnetic flux does not change with the radius of the stator 1. Therefore, the tooth shapes of the tooth parts a of the first radial teeth 15 in the radial cross-section and the tooth shapes of the tooth parts a of the second radial teeth 16 in the radial cross-section are both designed as rectangles, and the tooth slots formed between two adjacent first radial teeth 15 and the tooth slots formed between two adjacent second radial teeth 16 are both trapezoidal slots. This can avoid material waste caused by the large area of the radial tooth iron cores. Since the axial magnetic flux increases with the increase of the radius, the tooth shapes of the tooth parts a of the first axial teeth 17 in the radial cross-section and the tooth shapes of the tooth parts a of the second axial teeth 18 in the radial cross-section are both designed as trapezoids, and the tooth slots formed between two adjacent first axial teeth 17 and the tooth slots formed between two adjacent second axial teeth 18 are parallel slots. This can avoid magnetic saturation.

[0053] Exemplarily, as Figure 3 and Figure 4 shown, the rotor housing 21 is provided with a rotating housing 211, a rotating shaft sleeve 212, a front cover plate 213, and a rear cover plate 214. The front end of the rotating housing 211 is fixedly connected to the front cover plate 213. The rotating shaft sleeve 212 is rotatably connected to the central shaft 14 through a bearing. The front end of the rotating shaft sleeve 212 is fixedly connected to the front cover plate 213. The rear end of the rotating shaft sleeve 212 is fixedly connected to the rear cover plate 214. The rear cover plate 214 is disposed between the stator bracket 11 and the stator iron core 12. The first radial magnetic pole array 22 is fixedly disposed on the inner circumference of the rotating housing 211. The second radial magnetic pole array 23 is fixedly disposed on the outer circumference of the rotating shaft sleeve 212. The first axial magnetic pole array 24 is fixedly disposed on the inner side of the front cover plate 213. The second axial magnetic pole array 25 is fixedly disposed on the inner side of the rear cover plate 214. Such a design can integrate the first radial rotor, the second radial rotor, the first axial rotor, and the second axial rotor to ensure that the four rotor components can output torque synchronously, with a compact and reliable structure.

[0054] Exemplarily, in the case where the axial magnetic pole array and the axial stator teeth are distributed in a fan shape, as the radius increases, the area of the permanent magnet generating the air-gap magnetic flux will also increase accordingly. This means that the magnetic density at the back iron in the inner diameter direction of the axial magnetic pole array is small, while the magnetic density at the back iron in the outer diameter direction is large, as Figure 9As shown. This phenomenon is called the curvature effect, which causes an uneven gradient distribution of magnetic flux along the radial direction in the axial magnetic pole array. This uneven distribution results in some back iron not being saturated, thus causing material waste. However, most current axial magnetic pole arrays are simple transformations of radial magnetic pole arrays, and their back iron thickness is usually uniform. Traditional research usually only focuses on the influence of the curvature effect on the air-gap magnetic field distribution, while ignoring its influence on the back iron magnetic flux density distribution. In view of this problem, the embodiment of the present invention innovatively proposes an "axial magnetic pole array with unequal-thickness back iron", as Figure 10 shown, to effectively reduce the rotor weight. The specific design is as follows: As Figure 3 shown, a first embedding groove 215 for accommodating and fixing the first axial magnetic pole array 24 is provided on the inner side of the front cover plate 213. A first back iron 27 is provided on the bottom surface side of the first axial magnetic pole array 24 facing the first embedding groove 215. The thickness of the first back iron 27 gradually increases from the inner diameter to the outer diameter side of the front cover plate 213; a second embedding groove 216 for accommodating and fixing the second axial magnetic pole array 25 is provided on the inner side of the rear cover plate 214. A second back iron 28 is provided on the bottom surface side of the second axial magnetic pole array 25 facing the second embedding groove 216. The thickness of the second back iron 28 gradually increases from the inner diameter to the outer diameter side of the rear cover plate 214.

[0055] As Figure 10 shown, taking the axial magnetic pole array with unequal-thickness back iron as an example of a traditional strong magnetic focusing Halbach magnetic pole array, this unequal-thickness back iron design can effectively utilize the curvature effect at the back iron, reduce material waste, realize the light weight of the rotor, effectively reduce the axial rotor back iron mass by about 51.47% and does not affect the torque output (see Figure 11 ).

[0056] Exemplarily, at least one transition permanent magnet or soft magnet is provided in each pole pitch of the first radial magnetic pole array 22, the second radial magnetic pole array 23, the first axial magnetic pole array 24 and the second axial magnetic pole array 25; the radial magnetic pole array, the first axial magnetic pole array 24 and the second axial magnetic pole array 25 are all based on the center line of the permanent magnets corresponding to the same central angle and with the magnetization directions all facing the air gap or departing from the air gap. The magnetization directions of the respective transition permanent magnets in each pole pitch gradually change to depart from the air gap or face the air gap in the clockwise or counterclockwise direction. In this embodiment, the first radial magnetic pole array 22, the second radial magnetic pole array 23, the first axial magnetic pole array 24 and the second axial magnetic pole array 25 are all preferably Halbach magnetic pole arrays, as Figure 7As shown, it can generate a strong magnetic field on one side while the magnetic field on the other side is extremely weak or almost zero, which helps to obtain a more uniform magnetic field distribution in the radial or axial direction and reduce the dissipation of the magnetic field, and can reduce the usage amount of magnetic material while ensuring the magnetic field strength.

[0057] Exemplarily, as Figure 3 and Figure 4 shown, an output shaft 3 coaxial with the central axis 14 is installed on the outer side of the front cover plate 213 to facilitate power output to the outside.

[0058] In the description of the present invention, it should be understood that unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0059] The above-disclosed are only the preferred embodiments of the present invention, and of course cannot be used to limit the scope of rights of the present invention. Therefore, the equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. Axial radial composite flux electromagnetic drive with a hollow stator, comprising a rotor and a stator, characterized in that: The stator comprises a stator support, a stator core and a coil winding; the stator support is axially opposite to the stator core and is fixedly connected to the stator core by bolts; the stator support is fixedly connected with a central axis, the stator core is annular, the central axis is axially inserted into the middle of the stator core and is coaxial with the stator core; the outer periphery of the stator core is provided with a plurality of first radial teeth uniformly distributed in its circumferential direction, the inner periphery of the stator core is provided with a plurality of second radial teeth uniformly distributed in its circumferential direction, the front end of the stator core is provided with a plurality of first axial teeth uniformly distributed in its circumferential direction, and the rear end of the stator core is provided with a plurality of second axial teeth uniformly distributed in its circumferential direction; the coil winding is rectangular and surrounds the first radial teeth, the second radial teeth, the first axial teeth and the second axial teeth; The rotor comprises a rotor housing and a first radial magnetic pole array, a second radial magnetic pole array, a first axial magnetic pole array and a second axial magnetic pole array respectively fixed on the rotor housing; the rotor housing is rotatably connected to the central axis through a bearing; the first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array and the second axial magnetic pole array are all arranged in a circular ring shape, the first radial magnetic pole array and the first radial tooth are spaced to form a first radial air gap, the second radial magnetic pole array and the second radial tooth are spaced to form a second radial air gap, the first axial magnetic pole array and the first axial tooth are spaced to form a first An axial air gap, the second axial magnetic pole array and the second axial tooth are spaced relative to each other to form a second axial air gap; the first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array and the second axial magnetic pole array have the same pole pitch and the permanent magnets are aligned, the pole pitch: τ=360° / 2P, p is the number of pole pairs; the first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array and the second axial magnetic pole array are all based on the center line of the permanent magnet corresponding to the same central angle and the magnetization direction is toward the air gap or away from the air gap, and the magnetization direction of each permanent magnet passing through a pole pitch is alternately away from the air gap or toward the air gap; The first radial tooth, the second radial tooth, the first axial tooth and the second axial tooth are all provided with a tooth portion, a yoke portion connected to one end of the tooth portion and a pole shoe connected to the other end of the tooth portion; the yoke portion of the first radial tooth, the yoke portion of the second radial tooth, the yoke portion of the first axial tooth and the yoke portion of the second axial tooth enclose a hollow chamber with a rectangular axial cross-section.

2. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 1, characterized in that: The yoke of the first radial tooth and the yoke of the second radial tooth are connected through a spoke plate to form an integrated radial tooth; the first axial tooth is fixed to the front end of the integrated radial tooth by welding, screws or adhesive, and the second axial tooth is fixed to the rear end of the integrated radial tooth by welding, screws or adhesive.

3. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 2, characterized in that: A plurality of spoke plates are evenly distributed along the circumferential direction, and the plurality of spoke plates divide the hollow chamber into a plurality of chamber units; and aluminum blocks are embedded in the chamber units.

4. The axial radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 2, characterized in that: The axial ends of the yoke of the first radial tooth are respectively provided with first groove edges that match the outer periphery of the yoke of the first axial tooth or the second axial tooth, and the groove depth of the first groove edge is consistent with the thickness of the outer periphery of the yoke of the first axial tooth or the second axial tooth; the axial ends of the yoke of the second radial tooth are respectively provided with second groove edges that match the inner periphery of the yoke of the first axial tooth or the second axial tooth, and the groove depth of the second groove edge is consistent with the thickness of the inner periphery of the yoke of the first axial tooth or the second axial tooth.

5. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 1, characterized in that: The tooth shape of the tooth portion of the first radial tooth in the radial cross section is rectangular, and the tooth groove formed between two adjacent first radial teeth is a trapezoidal groove; the tooth shape of the tooth portion of the second radial tooth in the radial cross section is rectangular, and the tooth groove formed between two adjacent second radial teeth is a trapezoidal groove; the tooth shape of the tooth portion of the first axial tooth in the radial cross section is trapezoidal, and the tooth groove formed between two adjacent first axial teeth is a parallel groove; the tooth shape of the tooth portion of the second axial tooth in the radial cross section is trapezoidal, and the tooth groove formed between two adjacent second axial teeth is a parallel groove.

6. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator according to any one of claims 1 to 5, characterized in that: The rotor housing is provided with a rotating shell, a rotating sleeve, a front cover plate and a rear cover plate, the front end of the rotating shell is fixedly connected to the front cover plate, the rotating sleeve is rotatably connected to the central shaft through a bearing, the front end of the rotating sleeve is fixedly connected to the front cover plate, the rear end of the rotating sleeve is fixedly connected to the rear cover plate, and the rear cover plate is arranged between the stator bracket and the stator core; the first radial magnetic pole array is fixedly arranged on the inner periphery of the rotating shell, the second radial magnetic pole array is fixedly arranged on the outer periphery of the rotating sleeve, the first axial magnetic pole array is fixedly arranged on the inner side of the front cover plate, and the second axial magnetic pole array is fixedly arranged on the inner side of the rear cover plate.

7. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 6, characterized in that: The inner side of the front cover plate is provided with a first embedding groove for accommodating and fixing the first axial magnetic pole array, and the first axial magnetic pole array is provided with a first back iron on the bottom side facing the first embedding groove, and the thickness of the first back iron gradually increases from the inner diameter to the outer diameter of the front cover plate; the inner side of the rear cover plate is provided with a second embedding groove for accommodating and fixing the second axial magnetic pole array, and the second axial magnetic pole array is provided with a second back iron on the bottom side facing the second embedding groove, and the thickness of the second back iron gradually increases from the inner diameter to the outer diameter of the rear cover plate.

8. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 6, characterized in that: The first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array and the second axial magnetic pole array are each provided with at least one transition permanent magnet in each pole pitch; the radial magnetic pole array, the first axial magnetic pole array and the second axial magnetic pole array are all based on the center line of the permanent magnet corresponding to the same central angle and with the magnetization direction facing the air gap or away from the air gap, and the magnetization direction of each transition permanent magnet in each pole pitch is gradually transformed in a clockwise direction or counterclockwise direction to away from the air gap or toward the air gap.

9. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 8, characterized in that: The first radial magnetic pole array, the second radial magnetic pole array, the first axial magnetic pole array, and the second axial magnetic pole array are all Halbach magnetic pole arrays.

10. The axial-radial composite magnetic flux electromagnetic drive with a hollow stator as claimed in claim 6, characterized in that: An output shaft coaxially arranged with the central axis is installed on the outer side of the front cover plate.

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