Rotor assembly, motor and electrical equipment

Abstract

The present invention provides a rotor assembly, a motor, and an electrical appliance. The rotor assembly includes: a rotor core; a permanent magnet, one end face of the permanent magnet being connected to one end face of the rotor core; a rotor disc, connected to the other end face of the rotor core; a plastic-coated body, covering at least a part of the rotor core, at least a part of the permanent magnet, and at least a part of the rotor disc, so that the rotor disc, the rotor core, and the permanent magnet form an integral structure. The present invention adopts an integrated plastic coating design for the rotor core, the permanent magnet, and the rotor disc, effectively enhancing the structural strength of the rotor assembly, being beneficial to overcoming the centrifugal force during the rotation of the rotor disc, not only being beneficial to preventing the permanent magnet from falling off, but also reducing the axial deformation of the rotor caused by the axial magnetic field operation of the rotor, thereby avoiding the influence of the axial deformation of the rotor assembly on the air gap uniformity and the sinusoidality of the air gap magnetic density of the motor, being beneficial to ensuring the sinusoidality of the back electromotive force of the motor, and being beneficial to reducing the cogging torque and torque ripple of the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular, to a rotor assembly, a motor including the above rotor assembly, and an electrical device including the above motor. Background Art

[0002] In the application of disc motors, the centrifugal force and the axial magnetic suction force between the stator and rotor of the motor make the permanent magnets prone to falling off, which has become a major problem restricting the application of disc motors. At present, manufacturers generally adopt the method of bonding permanent magnets on the surface of the rotor core. However, the disadvantage of this traditional structure is that during the operation of the disc motor, the directly bonded permanent magnets are not firm and are prone to falling off entirely or partially, posing a great risk to the operation of the motor. There is also the method of pressing the permanent magnet with a whole pressing plate, and the disadvantage of this structure is that the eddy current loss in the pressing plate is large, and because the pressing plate has a thickness, the air gap of the motor is increased, affecting the air gap magnetic density of the motor and the utilization rate of the permanent magnet. Summary of the Invention

[0003] In order to solve at least one of the above technical problems, an object of the first aspect of the present invention is to provide a rotor assembly.

[0004] Another object of the present invention is to provide a motor including the above rotor assembly.

[0005] Still another object of the present invention is to provide an electrical device including the above motor.

[0006] To achieve the above object, a technical solution of the first aspect of the present invention provides a rotor assembly, including: a rotor core; a permanent magnet, one end face of the permanent magnet being connected to one end face of the rotor core; a rotor disc, the rotor disc being made of a non-magnetic material, the rotor disc being connected to the other end face of the rotor core; a plastic-coated body, the plastic-coated body covering at least a part of the rotor core, at least a part of the permanent magnet, and at least a part of the rotor disc, so that the rotor core, the permanent magnet, and the rotor disc form an integral structure.

[0007] The rotor assembly provided by the technical solution of the first aspect of the present invention forms an integral structure of the rotor core, the permanent magnet, and the rotor disc by means of integral plastic coating, realizing the fixed connection of the rotor disc, the rotor core, and the permanent magnet. Compared with the existing bonding method, the plastic coating effectively enhances the connection strength between the rotor core and the permanent magnet, and the plastic-coated body also plays a fixing and limiting role for the permanent magnet, and increases the connection area between the permanent magnet and other structures, thus avoiding the risk of the whole or partial falling off of the permanent magnet caused by the insecure surface bonding method in the prior art, effectively preventing the permanent magnet from falling off, and further improving the operation reliability of the axial-flux permanent magnet motor (or disc motor).

[0008] The setting of the rotor disk facilitates the fixed connection with the rotating shaft of the motor by using the rotor disk, without the need for the rotor core to be fixedly connected to the rotating shaft. This not only helps reduce the connection difficulty between the rotor assembly and the rotating shaft but also helps ensure the operation reliability of the rotor assembly. At the same time, the non-magnetic rotor disk, compared with the existing pressing plate scheme, not only reduces the eddy current loss but also helps ensure the overall strength of the rotor assembly and the flatness of the plane where the rotor disk contacts the rotor core.

[0009] The rotor core, permanent magnet, and rotor disk are designed in an integrally plastic-coated form, forming an integrated structure. This effectively enhances the structural strength of the rotor assembly, helps overcome the centrifugal force during the rotation of the rotor disk, not only further prevents the permanent magnet from falling off but also reduces the axial deformation of the rotor caused by the axial magnetic field operation of the rotor, thus avoiding the influence on the air gap uniformity and air gap magnetic density sinusoid of the motor due to the axial deformation of the rotor assembly, helping ensure the sinusoid of the motor back electromotive force, and helping reduce the cogging torque and torque ripple of the motor.

[0010] In addition, the rotor assembly in the above technical solution provided by the present invention may also have the following additional technical features:

[0011] In any of the above technical solutions, the rotor core is formed by stacking silicon steel sheets along the axial direction of the rotor core.

[0012] Compared with the conventional integral rotor core, the rotor core in this solution adopts a silicon steel sheet stacking design, which helps further reduce the eddy current loss in the rotor disk, thereby improving the operation efficiency of the motor.

[0013] In the above technical solution, the rotor core is an integrally formed structure by welding.

[0014] The rotor core is formed into an integrated structure by welding. The welding strength is high and the process is mature, so it not only helps improve the structural strength of the rotor core but also helps reduce the process difficulty. Of course, the rotor core can also be formed into one body by gluing.

[0015] In the above technical solution, the number of permanent magnets is multiple. The multiple permanent magnets are surface-mounted on the rotor core, and the multiple permanent magnets are arranged in a circular array around the central axis of the rotor core.

[0016] By adopting the surface-mounted permanent magnet method, the assembly between the permanent magnet and the rotor core is realized, which simplifies the process difficulty, helps improve the production efficiency, further improves the connection strength between the permanent magnet and the rotor core, and further improves the use reliability of the motor. The multiple permanent magnets are arranged in a circular array around the central axis of the rotor core, with a regular structure and conducive to the stable operation of the motor.

[0017] In any of the above technical solutions, the end face of the permanent magnet away from the rotor core protrudes from the plastic-coated body.

[0018] The end face of the permanent magnet away from the rotor core protruding from the plastic-coated body is conducive to reducing the distance between the permanent magnet and the stator, which is beneficial to the design of a small air gap of the motor, thereby reducing the amount of permanent magnet used, improving the utilization rate of the permanent magnet, and increasing the power density of the motor. Specifically, the end face of the plastic-coated body away from the rotor core is denoted as the plastic-coated end face, the two end faces of the permanent magnet are respectively denoted as the first end face and the second end face, the first end face protrudes from the plastic-coated end face, and the second end face is connected to the end face of the rotor core. Of course, the permanent magnet can also be completely covered by the plastic-coated body.

[0019] In any of the above technical solutions, an outer groove is provided on the outer side surface of the rotor core, the plastic-coated body has an outer protrusion adapted to the outer groove, and the outer protrusion is embedded in the outer groove; and / or the rotor core is of an annular structure, an inner groove is provided on the inner side surface of the rotor core, the plastic-coated body has an inner protrusion adapted to the inner groove, and the inner protrusion is embedded in the inner groove.

[0020] When an outer groove is provided on the outer side surface of the rotor core, during plastic coating, the liquid plastic will flow into the outer groove and solidify to form an outer protrusion, so that a part of the plastic-coated body is embedded in the outer groove, which is beneficial to increasing the contact area between the rotor core and the plastic-coated body, and further improving the connection strength between the rotor core and the plastic-coated body. At the same time, the outer groove can also be used as a welding position to facilitate the welding and forming of the rotor core.

[0021] Similarly, when an inner groove is provided on the inner side surface of the rotor core, during plastic coating, the liquid plastic will flow into the inner groove and solidify to form an inner protrusion, so that a part of the plastic-coated body is embedded in the inner groove, which is also beneficial to increasing the contact area between the rotor core and the plastic-coated body, and further improving the connection strength between the rotor core and the plastic-coated body.

[0022] In the above technical solution, the rotor disc is of an annular structure, a through hole is provided on the inner side surface of the rotor disc, the through hole corresponds to the inner groove of the rotor core, and the plastic-coated body has a connecting column, and the connecting column is embedded in the through hole and the inner groove.

[0023] When a through hole is provided on the inner side surface of the rotor disc and the position of the through hole corresponds to the inner groove of the rotor core, during plastic coating, the liquid plastic will flow into the through hole and the inner groove and solidify to form a connecting column, so that the rotor disc and the rotor core are tightly fixed together, which is beneficial to improving the connection strength between the rotor disc and the rotor core.

[0024] The middle part of the rotor disk is provided with a shaft hole for accommodating the rotating shaft of the motor. Further, a positioning groove is provided on the inner side surface of the rotor core, and a positioning hole is provided on the inner side surface of the rotor disk. The positioning hole corresponds to and communicates with the positioning groove, facilitating the accurate alignment of the rotor core and the rotor disk during assembly.

[0025] In any of the above technical solutions, the permanent magnet includes: two end faces; and a side circumferential surface, the side circumferential surface includes a first side surface, an outer side surface, a second side surface, and an inner side surface that are sequentially connected end to end. The projections of the first side surface, the outer side surface, the second side surface, and the inner side surface on the end face are respectively a first side line segment, an outer side line segment, a second side line segment, and an inner side line segment. The projection of the side circumferential surface on the end face is an axisymmetric structure. The connection line between the midpoints of the inner side line segment and the outer side line segment forms the axis of symmetry of the axisymmetric structure, and this axis of symmetry is configured to be perpendicular to and intersect with the central axis of the rotor assembly of the motor; wherein, both the inner side line segment and the outer side line segment include two edge arc segments and an intermediate segment located between the two edge arc segments, and the centers of the two edge arc segments of the inner side line segment and / or the centers of the two edge arc segments of the outer side line segment are located between the central axis and the outer side line segment.

[0026] In this solution, the inner side surface and the outer side surface of the permanent magnet both adopt an optimized arc shape. On the one hand, it is beneficial to increase the end distance between two adjacent permanent magnets, thereby reducing the magnetic leakage between their corners. On the basis of using less permanent magnet material, the utilization rate of the permanent magnet is improved; on the other hand, the optimized arc design is beneficial to the sinusoidalization of the air-gap magnetic field, which is beneficial to reducing the back electromotive force harmonics, cogging torque, and torque ripple.

[0027] Specifically, for the existing sector-shaped permanent magnets, their inner side surfaces and outer side surfaces are concentrically arranged around the central axis of the rotor assembly. That is to say, the centers of the projections of the inner side surfaces and the outer side surfaces of the existing sector-shaped permanent magnets on the end face of the permanent magnet coincide with the projection of the central axis of the rotor assembly on the end face of the permanent magnet. In this way, the outer side surfaces of two adjacent permanent magnets are located on the same cylindrical surface, and the inner side surfaces are also located on the same cylindrical surface. Therefore, the end distance between two adjacent permanent magnets is equal to the distance between the first side surface and the second side surface of two adjacent permanent magnets.

[0028] In this application, the shape of the permanent magnet is optimized. The two edge arc segments of the inner line are symmetrically arranged on both sides of the middle segment of the inner line, and the two edge arc segments of the outer line are symmetrically arranged on both sides of the middle segment of the outer line. When the centers of the two edge arc segments of the inner line are located between the central axis of the rotor assembly and the outer line, compared with the existing sector-shaped permanent magnet, the radius of the inner corner part of the permanent magnet in this application is reduced. In this way, the edge parts of the inner sides of two adjacent permanent magnets are not on the same cylindrical surface, and compared with the prior art, it is equivalent to the edge part of the inner side having a deeper bending degree, resulting in the inner corner contracting towards the middle part. This is beneficial to increasing the distance between the inner ends of adjacent permanent magnets, thereby being able to reduce the magnetic leakage at the inner corners of the permanent magnet, improve the utilization rate of the magnet steel, and make the air gap sinusoidal, reducing the back electromotive force harmonics, cogging torque, and torque ripple.

[0029] Similarly, when the centers of the two edge arc segments of the outer line are located between the central axis and the outer line, compared with the existing sector-shaped permanent magnet, the radius of the outer corner part of the permanent magnet in this application is reduced. In this way, the edge parts of the outer sides of two adjacent permanent magnets are not on the same cylindrical surface, and compared with the prior art, it is equivalent to the edge part of the outer side having a deeper bending degree, resulting in the inner corner contracting towards the middle part. This is beneficial to increasing the distance between the outer ends of adjacent permanent magnets, thereby being able to reduce the magnetic leakage at the outer corners of the permanent magnet, and make the air gap sinusoidal, reducing the back electromotive force harmonics, cogging torque, and torque ripple. At the same time, the permanent magnet in this application has a symmetric structure, regular shape, and is convenient for processing.

[0030] It can be understood that in this application, the permanent magnet can be a magnet steel or a permanent magnet made of other permanent magnetic materials. The motor is an axial-flux permanent magnet motor, or a disc motor.

[0031] Among them, the central axis of the air gap of the motor is collinear with the central axis of the rotor assembly. Therefore, the projection of the central axis of the rotor assembly on the end face of the permanent magnet can also be recorded as the air gap center of the motor. Therefore, in the prior art, the centers of the projections of the inner side and the outer side of the sector-shaped permanent magnet on the end face of the permanent magnet coincide with the air gap center. In this application, however, the center of the edge arc segment deviates from the air gap center and does not coincide with the air gap center. The middle segments of the inner line and the outer line can be straight line segments or arc segments.

[0032] In the above technical solution, the middle segment of the inner line is an arc segment.

[0033] The middle segment of the inner line being an arc segment makes the inner line smoother and is convenient for the permanent magnet to be processed and formed.

[0034] In the above technical solution, the middle segment of the inner line coincides with the centers of the two edge arc segments of the inner line.

[0035] In the above technical solution, the center of the inner line is located on the axis of symmetry.

[0036] With such a design, the inner line is actually an arc, and the center of this arc is located on the axis of symmetry. Therefore, the inner side is located on a cylindrical surface and can be integrally formed, which is convenient for processing and is beneficial to improving the processing efficiency of the permanent magnet.

[0037] In the above technical solution, the inner line bends and protrudes away from the outer line; or the inner line bends and protrudes towards the outer line.

[0038] If the inner line bends and protrudes away from the outer line, then the inner line bends and protrudes towards the central axis of the rotor assembly. This is beneficial to further increasing the distance between the inner ends of two adjacent permanent magnets, thereby further reducing the magnetic leakage between the inner corners of adjacent permanent magnets and is beneficial to improving the utilization rate of the magnet steel.

[0039] Alternatively, the inner line can also bend and protrude towards the outer line as required, and the specific choice is made according to the actual application conditions.

[0040] In any of the above technical solutions, the two edge arc segments of the outer line are respectively denoted as the first arc segment and the second arc segment, the middle segment of the outer line is an arc segment and is denoted as the middle arc segment. The first arc segment and the second arc segment are symmetrical about the axis of symmetry, and the centers of the first arc segment and the second arc segment are the same. The center of the middle arc segment is located on the axis of symmetry.

[0041] With such a design, the shape of the permanent magnet is more regular and the structure is more symmetrical. Therefore, the processing difficulty is further reduced, which is beneficial to further improving the processing efficiency of the permanent magnet.

[0042] In the above technical solution, the centers of the first arc segment, the second arc segment and the inner line are the same, and the center of the middle arc segment deviates from the center of the inner line; or the centers of the first arc segment, the middle arc segment and the second arc segment are the same, and the center of the outer line deviates from the center of the inner line; or the center of the middle arc segment and the center of the inner line are the same, and the center of the middle arc segment deviates from the centers of the first arc segment and the second arc segment; or the centers of the first arc segment, the middle arc segment, the second arc segment and the inner line are the same; or the centers of the first arc segment and the second arc segment, the center of the middle arc segment and the center of the inner line deviate from each other.

[0043] For the case where the inner line is a complete arc, the centers of the inner line (denoted as O2), the centers of the first and second arc segments of the outer line (denoted as O3), and the center of the middle arc segment (denoted as O1) have the following five positional relationships:

[0044] O2 and O3 coincide and deviate from O1, being inconsistent with O1. This design enables the arc surface corresponding to the first arc segment (denoted as the first side arc surface), the arc surface corresponding to the second arc segment (denoted as the second side arc surface), and the inner side surface (which can also be called the inner arc surface) to be processed through the same process, thus facilitating the improvement of the processing efficiency of the permanent magnet.

[0045] O1 and O3 coincide and deviate from O2, being inconsistent with O2. This design enables the entire outer side surface (which can also be called the outer arc surface) to be processed through the same process, thus facilitating the improvement of the processing efficiency of the permanent magnet.

[0046] O1 and O2 coincide and deviate from O3, being inconsistent with O3. This design enables the inner side surface (which can also be called the inner arc surface) and the middle arc segment (which can also be called the middle surface) to be processed through the same process, thus facilitating the improvement of the processing efficiency of the permanent magnet.

[0047] O1, O2, and O3 coincide. This design enables the inner side surface (which can also be called the inner arc surface) and the entire outer side surface (which can also be called the outer arc surface) to be processed through the same process. The conventional disc-shaped permanent magnet can be quickly formed by trimming the two side surfaces, reducing the processing difficulty and facilitating the improvement of the processing efficiency of the permanent magnet.

[0048] Alternatively, O1, O2, and O3 can also be all inconsistent, and the specific shape of the permanent magnet can be reasonably designed according to the specific needs of the motor.

[0049] In any of the above technical solutions, the first side line and the edge arc segment are smoothly transitioned; the second side line and the edge arc segment are smoothly transitioned.

[0050] This design facilitates the processing and forming of the permanent magnet and is conducive to improving the processing efficiency of the permanent magnet.

[0051] In any of the above technical solutions, the first side line and the second side line are both straight line segments, and the extension lines of the first side line and the second side line intersect to form an angle α, and the following is satisfied between α and the number of pole pairs P of the rotor assembly: α = 180° / P.

[0052] If the number of pole pairs of the rotor is P, then the number of permanent magnets included in the rotor assembly is 2 times that of P. This design facilitates the uniform arrangement of multiple permanent magnets along the circumferential direction of the rotor assembly.

[0053] In the above technical solution, the intersection point of the extension lines of the first side line and the second side line is located on the axis of symmetry and between the central axis and the inner side line.

[0054] Such a design is conducive to further increasing the end distance between two adjacent permanent magnets, thereby further improving the corner leakage magnetic flux and further enhancing the motor performance.

[0055] A second aspect of the technical solution of the present invention provides a motor, including: a stator assembly; and a rotor assembly as described in any one of the technical solutions of the first aspect, the rotor assembly being cooperated with the stator assembly and adapted to rotate relative to the stator assembly.

[0056] The motor provided by the technical solution of the second aspect of the present invention includes the rotor assembly as described in any one of the technical solutions of the first aspect, and thus has all the beneficial effects of any of the above technical solutions, which will not be elaborated herein.

[0057] Specifically, the motor is an axial flux permanent magnet motor, or a disc motor.

[0058] A third aspect of the technical solution of the present invention provides an electrical equipment, including: a device main body; and a motor as described in the technical solution of the second aspect, the motor being connected to the device main body.

[0059] The electrical equipment provided by the technical solution of the third aspect of the present invention includes the motor as described in the technical solution of the second aspect, and thus has all the beneficial effects of any of the above technical solutions, which will not be elaborated herein.

[0060] In the above technical solution, the electrical equipment may be, but is not limited to: compressors, fans, pumps, household appliances such as refrigerators and air conditioners, vehicles, industrial equipment such as multi-connected units, etc.

[0061] The additional aspects and advantages of the present invention will become apparent in the following description section or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0063] Figure 1 is a schematic structural diagram of a rotor assembly according to some embodiments of the present invention;

[0064] Figure 2 is a schematic structural diagram of a magnetic steel according to an embodiment of the present invention;

[0065] Figure 3 is a schematic structural diagram of a magnetic steel according to an embodiment of the present invention;

[0066] Figure 4 is a schematic structural diagram of the permanent magnet according to an embodiment of the present invention;

[0067] Figure 5 is a schematic structural diagram of the permanent magnet according to an embodiment of the present invention;

[0068] Figure 6 is a schematic structural diagram of the permanent magnet according to an embodiment of the present invention;

[0069] Figure 7 is a schematic three-dimensional structural diagram of the permanent magnet according to an embodiment of the present invention;

[0070] Figure 8 is a schematic structural diagram of the rotor core according to some embodiments of the present invention;

[0071] Figure 9 is a schematic structural diagram of the rotor disc according to some embodiments of the present invention;

[0072] Figure 10 is a schematic structural diagram of the plastic-coated body according to some embodiments of the present invention;

[0073] Figure 11 is a schematic block diagram of the motor according to some embodiments of the present invention;

[0074] Figure 12 is a schematic block diagram of the electrical equipment according to some embodiments of the present invention.

[0075] Among them, Figures 1 to 12 the corresponding relationship between the reference numerals and the component names in the figures is as follows:

[0076] 1 Rotor assembly, 10 Permanent magnet, 20 Rotor core, 30 Rotor disc, 40 Plastic-coated body;

[0077] 11 First side, 110 Second side, 111 First side line, 112 Second side line; 120 Inner side, 121 Inner side line; 130 Outer side, 131 First arc segment, 132 Second arc segment, 133 Intermediate arc segment; 141 First end face, 142 Second end face;

[0078] 21 Inner groove, 22 Outer groove;

[0079] 31 Through hole, 32 Shaft hole;

[0080] 41 Outer protrusion, 42 Connecting column, 43 Plastic-coated end face;

[0081] 100 Motor, 102 Stator assembly;

[0082] 200 Electrical equipment, 202 Equipment main body. Detailed Implementation Modes

[0083] In order to more clearly understand the above objects, features, and advantages of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation modes. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0084] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0085] The following refers to Figures 1 to 12 Describe the rotor assembly, motor, and electrical equipment according to some embodiments of the present invention.

[0086] As Figure 1 shown, the rotor assembly 1 provided by the embodiment of the first aspect of the present invention includes: a rotor core 20, a permanent magnet 10, a rotor disk 30, and a plastic coating body 40.

[0087] Specifically, one end face of the permanent magnet 10 is connected to one end face of the rotor core 20.

[0088] The rotor disk 30 is made of a non-magnetic material, and the rotor disk 30 is connected to the other end face of the rotor core 20.

[0089] The plastic coating body 40 covers at least a part of the rotor core 20, at least a part of the permanent magnet 10, and at least a part of the rotor disk 30, as Figure 1 shown, so that the rotor core 20, the permanent magnet 10, and the rotor disk 30 form an integral structure.

[0090] The rotor assembly 1 provided by the embodiment of the first aspect of the present invention uses an integral plastic coating form to make the rotor core 20, the permanent magnet 10, and the rotor disk 30 form an integral structure, realizing the fixed connection of the rotor disk 30, the rotor core 20, and the permanent magnet 10. Compared with the existing bonding method, the plastic coating form effectively enhances the connection strength between the rotor core 20 and the permanent magnet 10, and the plastic coating body 40 also plays a fixing and limiting role for the permanent magnet 10, and increases the connection area between the permanent magnet 10 and other structures, thereby avoiding the risk of the whole or partial detachment of the permanent magnet 10 caused by the insecure surface bonding method in the prior art, effectively preventing the detachment of the permanent magnet 10, and further improving the operation reliability of the axial-flux permanent magnet motor (or called disk motor).

[0091] The arrangement of the rotor disk 30 facilitates the fixed connection with the rotating shaft of the motor by using the rotor disk 30, without the need for the rotor core 20 to be fixedly connected to the rotating shaft. This not only helps reduce the connection difficulty between the rotor assembly 1 and the rotating shaft but also helps ensure the operational reliability of the rotor assembly 1.

[0092] At the same time, the non-magnetic rotor disk 30, compared with the existing pressing plate solution, not only reduces eddy current losses but also helps ensure the overall strength of the rotor assembly 1 and the flatness of the contact plane between the rotor disk 30 and the rotor core 20.

[0093] The rotor core 20, the permanent magnet 10, and the rotor disk 30 are designed in an integrally overmolded form, forming an integrated structure. This effectively enhances the structural strength of the rotor assembly 1, helps overcome the centrifugal force during the rotation of the rotor disk 30, not only further prevents the permanent magnet 10 from falling off but also reduces the axial deformation of the rotor caused by the axial magnetic field operation of the rotor, thus avoiding the influence of the axial deformation of the rotor assembly 1 on the air gap uniformity and the sinusoidality of the air gap magnetic density of the motor, helping ensure the sinusoidality of the back electromotive force of the motor, and helping reduce the cogging torque and torque ripple of the motor.

[0094] Of course, for some motors, the rotor disk can also be removed, and the permanent magnet is directly connected to the rotor core. The rotor core can be connected to the rotating shaft by injection molding.

[0095] Specifically, the number of permanent magnets 10 is multiple, as Figure 1 shown. Multiple permanent magnets 10 are surface-mounted on the rotor core 20, and multiple permanent magnets 10 are arranged in a circular array around the central axis of the rotor core 20.

[0096] By using the method of surface-mounting the permanent magnet 10, the assembly between the permanent magnet 10 and the rotor core 20 is realized, simplifying the process difficulty, helping improve production efficiency, further enhancing the connection strength between the permanent magnet 10 and the rotor core 20, and further improving the operational reliability of the motor. Multiple permanent magnets 10 are arranged in a circular array around the central axis of the rotor core 20, with a regular structure and being beneficial to the stable operation of the motor.

[0097] Furthermore, the end face of the permanent magnet 10 away from the rotor core 20 protrudes from the overmolded body 40, as Figure 1 shown.

[0098] The end face of the permanent magnet 10 away from the rotor core 20 protruding from the overmolded body 40 helps reduce the distance between the permanent magnet 10 and the stator, which is beneficial to the design of a small air gap for the motor, thus reducing the usage amount of the permanent magnet 10, improving the utilization rate of the permanent magnet 10, and increasing the power density of the motor.

[0099] Specifically, the end face of the plastic-coated body 40 away from the rotor core 20 is recorded as the plastic-coated end face 43, and the two end faces of the permanent magnet 10 are recorded as the first end face 141 and the second end face 142, respectively. The first end face 141 protrudes from the plastic-coated end face 43, and the second end face 142 is connected to the end face of the rotor core 20. The distance between the first end face 141 and the plastic-coated end face 43 is H, as shown in FIG. Figure 1 As shown, the size of H can be adjusted as needed.

[0100] Of course, the permanent magnet 10 can also be completely covered by the overmolding body 40 .

[0101] In some embodiments, further, the rotor core 20 is formed by laminating silicon steel sheets along the axial direction of the rotor core 20, such as Figure 1 shown.

[0102] Compared with the conventional integral rotor core 20 , the rotor core 20 of this solution adopts a stacked silicon steel sheet design, which is beneficial to further reduce the eddy current loss in the rotor disk 30 , thereby improving the operating efficiency of the motor.

[0103] Of course, the rotor core 20 may also adopt an integral structure, directly using a block of solid magnetic conductive material.

[0104] The rotor core 20 is an integrated structure formed by welding.

[0105] The rotor core 20 is formed into an integrated structure by welding, and the welding strength is high and the process is mature, so it is beneficial to improve the structural strength of the rotor core 20 and reduce the process difficulty.

[0106] Of course, the rotor core 20 can also be formed as a whole by gluing.

[0107] In any of the above embodiments, further, the outer side surface 130 of the rotor core 20 is provided with an outer groove 22, such as Figure 8 The plastic package 40 has an outer protrusion 41 adapted to the outer groove 22, as shown in FIG. Figure 10 The outer protrusion 41 is embedded in the outer groove 22 .

[0108] Furthermore, the rotor core 20 is an annular structure, such as Figure 8 The inner side surface 120 of the rotor core 20 is provided with an inner groove 21, as shown in FIG. Figure 8 The plastic package 40 has an inner protrusion that matches the inner groove 21, as shown in FIG. Figure 10 The inner protrusion is embedded in the inner groove 21.

[0109] An outer groove 22 is provided on the outer side surface 130 of the rotor core 20. During the overmolding process, the liquid plastic will flow into the outer groove 22 and solidify to form an outer protrusion 41, so that a part of the overmolded body 40 is embedded in the outer groove 22. This is beneficial to increasing the contact area between the rotor core 20 and the overmolded body 40, thereby improving the connection strength between the rotor core 20 and the overmolded body 40. At the same time, the outer groove 22 can also serve as a welding position, facilitating the welding and forming of the rotor core 20.

[0110] Among them, the number of the outer grooves 22 is multiple, and the multiple outer grooves 22 are distributed at intervals along the circumferential direction of the rotor core 20, and are further evenly distributed.

[0111] Similarly, an inner groove 21 is provided on the inner side surface 120 of the rotor core 20. During the overmolding process, the liquid plastic will flow into the inner groove 21 and solidify to form an inner protrusion, so that a part of the overmolded body 40 is embedded in the inner groove 21. This is also beneficial to increasing the contact area between the rotor core 20 and the overmolded body 40, thereby improving the connection strength between the rotor core 20 and the overmolded body 40.

[0112] Among them, the number of the inner grooves 21 is multiple, and the multiple inner grooves 21 are distributed at intervals along the circumferential direction of the rotor core 20, and are further evenly distributed.

[0113] Furthermore, the rotor disc 30 is of an annular structure, as Figure 9 shown. A through hole 31 is provided on the inner side surface 120 of the rotor disc 30, as Figure 9 shown. The through hole 31 corresponds to the inner groove 21 of the rotor core 20. The overmolded body 40 has a connecting column 42, as Figure 10 shown. The connecting column 42 is embedded in the through hole 31 and the inner groove 21.

[0114] A through hole 31 is provided on the inner side surface 120 of the rotor disc 30, and the position of the through hole 31 corresponds to that of the inner groove 21 of the rotor core 20. During the overmolding process, the liquid plastic will flow into the through hole 31 and the inner groove 21 and solidify to form the connecting column 42, so that the rotor disc 30 and the rotor core 20 are tightly connected together, which is beneficial to improving the connection strength between the rotor disc 30 and the rotor core 20.

[0115] It can be understood that the part of the connecting column 42 located in the inner groove 21 is the aforementioned inner protrusion.

[0116] Among them, a shaft hole 32 is provided in the middle of the rotor disc 30 for accommodating the rotating shaft of the motor. Furthermore, a positioning groove is also provided on the inner side surface 120 of the rotor core 20, as Figure 8 shown. A positioning hole is also provided on the inner side surface 120 of the rotor disc 30, as Figure 9 shown. The positioning hole corresponds to and communicates with the positioning groove, facilitating the accurate alignment of the rotor core 20 and the rotor disc 30 during assembly.

[0117] In a specific embodiment, the number of positioning grooves is two, the two positioning grooves are symmetrically arranged, and the size of the positioning grooves is smaller than that of the inner groove 21. The positioning grooves are located at the middle positions between two adjacent inner grooves 21. Correspondingly, the number of positioning holes is two, and the size of the positioning holes is smaller than that of the through holes 31. The positioning holes are located at the middle positions between two adjacent through holes 31.

[0118] In any of the above embodiments, further, the permanent magnet 10 includes: two end faces and a side peripheral surface, as Figure 7 shown.

[0119] Specifically, the side peripheral surface includes a first side surface 11, an outer side surface 130, a second side surface 110, and an inner side surface 120 that are sequentially connected end to end, as Figure 7 shown. The projections of the first side surface 11, the outer side surface 130, the second side surface 110, and the inner side surface 120 on the end face are a first side line 111, an outer side line, a second side line 112, and an inner side line 121 respectively, as Figures 2 to 6 shown. The projection of the side peripheral surface on the end face is an axisymmetric structure. The connection line between the midpoints of the inner side line 121 and the outer side line forms the axis of symmetry of the axisymmetric structure, and this axis of symmetry is configured to be perpendicular to and intersect with the central axis of the rotor assembly 1 of the motor. Both the inner side line 121 and the outer side line include two edge arc segments and an intermediate segment located between the two edge arc segments.

[0120] Among them, the centers of the two edge arc segments of the inner side line 121 are located between the central axis and the outer side line.

[0121] Or, the centers of the two edge arc segments of the outer side line are located between the central axis and the outer side line.

[0122] Or, the centers of the two edge arc segments of the inner side line 121 and the centers of the two edge arc segments of the outer side line are located between the central axis and the outer side line.

[0123] In this solution, the inner side surface 120 and the outer side surface 130 of the permanent magnet 10 both adopt an optimized arc shape. On the one hand, it is beneficial to increase the end distance between two adjacent permanent magnets 10, thereby reducing the magnetic leakage between their corners. On the basis of using less permanent magnet 10, the utilization rate of the permanent magnet 10 is improved; on the other hand, the optimized arc design is beneficial to the sinusoidalization of the air-gap magnetic field, which is beneficial to reducing the back electromotive force harmonics, cogging torque, and torque ripple.

[0124] Specifically, for the existing sector permanent magnet 10, its inner side surface 120 and outer side surface 130 are both concentrically arranged around the central axis of the rotor assembly 1. That is to say, the centers of the projections of the inner side surface 120 and the outer side surface 130 of the existing sector permanent magnet 10 on the end surface of the permanent magnet 10 coincide with the projection of the central axis of the rotor assembly 1 on the end surface of the permanent magnet 10. In this way, the outer side surfaces 130 of two adjacent permanent magnets 10 are located on the same cylindrical surface, and the inner side surfaces 120 are also located on the same cylindrical surface. Therefore, the end distance between two adjacent permanent magnets 10 is equal to the spacing between the first side surface 11 and the second side surface 110 of two adjacent permanent magnets 10.

[0125] In this application, the shape of the permanent magnet 10 is optimized. The two edge arc segments of the inner side line 121 are symmetrically arranged on both sides of the middle segment of the inner side line 121, and the two edge arc segments of the outer side line are symmetrically arranged on both sides of the middle segment of the outer side line. When the centers of the two edge arc segments of the inner side line 121 are located between the central axis of the rotor assembly 1 and the outer side line, compared with the existing sector permanent magnet 10, the radius of the inner corner part of the permanent magnet 10 in this application is reduced. In this way, the edge parts of the inner side surfaces 120 of two adjacent permanent magnets 10 are not on the same cylindrical surface, and compared with the prior art, it is equivalent to that the bending degree of the edge part of the inner side surface 120 is deepened, resulting in the shrinkage of the inner corner towards the middle part. This is beneficial to increasing the distance between the inner ends of adjacent permanent magnets 10, thereby reducing the magnetic leakage at the inner corners of the permanent magnet 10, improving the utilization rate of the magnet steel, making the air gap sinusoidal, and reducing the back electromotive force harmonics, cogging torque and torque ripple.

[0126] Similarly, when the centers of the two edge arc segments of the outer side line are located between the central axis and the outer side line, compared with the existing sector permanent magnet 10, the radius of the outer corner part of the permanent magnet 10 in this application is reduced. In this way, the edge parts of the outer side surfaces 130 of two adjacent permanent magnets 10 are not on the same cylindrical surface, and compared with the prior art, it is equivalent to that the bending degree of the edge part of the outer side surface 130 is deepened, resulting in the shrinkage of the inner corner towards the middle part. This is beneficial to increasing the distance between the outer ends of adjacent permanent magnets 10, thereby reducing the magnetic leakage at the outer corners of the permanent magnet 10, making the air gap sinusoidal, and reducing the back electromotive force harmonics, cogging torque and torque ripple. At the same time, the permanent magnet 10 in this application has a symmetric structure, regular shape and is convenient for processing.

[0127] Among them, the central axis of the air gap of the motor is collinear with the central axis of the rotor assembly 1. Therefore, the projection of the central axis of the rotor assembly 1 on the end face of the permanent magnet 10 can also be denoted as the center of the air gap of the motor. Therefore, in the prior art, the centers of the projections of the inner side surface 120 and the outer side surface 130 of the sector-shaped permanent magnet 10 on the end face of the permanent magnet 10 coincide with the center of the air gap. In this application, however, the center of the edge arc segment deviates from the center of the air gap and does not coincide with it. The middle segments of the inner line 121 and the outer line can be straight line segments or arc segments.

[0128] It can be understood that in this application, the permanent magnet 10 can be a magnetic steel or a permanent magnet 10 made of other permanent magnetic materials. The motor is an axial flux permanent magnet motor, also called a disc motor.

[0129] Further, the middle segment of the inner line 121 is an arc segment.

[0130] The middle segment of the inner line 121 being an arc segment makes the inner line 121 relatively smooth, facilitating the processing and forming of the permanent magnet 10.

[0131] Further, the center of the middle segment of the inner line 121 coincides with the centers of the two edge arc segments of the inner line 121, as Figures 2 to 6 shown.

[0132] Among them, the center of the inner line 121 is located on the axis of symmetry, as Figures 2 to 6 shown.

[0133] With such a design, the inner line 121 is actually an arc, and the center of this arc is located on the axis of symmetry. Thus, the inner side surface 120 is located on a cylindrical surface and can be integrally formed, which is convenient for processing and helps improve the processing efficiency of the permanent magnet 10.

[0134] Further, the inner line 121 bends and protrudes in a direction away from the outer line, as Figures 2 to 6 shown.

[0135] When the inner line 121 bends and protrudes in a direction away from the outer line, the inner line 121 bends and protrudes in a direction closer to the central axis of the rotor assembly 1. This is beneficial for further increasing the distance between the inner ends of two adjacent permanent magnets 10, thereby further reducing the leakage magnetic field between the inner corners of adjacent permanent magnets 10 and helping to improve the utilization rate of the magnetic steel.

[0136] Of course, the inner line 121 can also bend and protrude in a direction closer to the outer line according to needs, being close to the shape of the sector-shaped permanent magnet 10 in the prior art, and is specifically selected according to actual application conditions.

[0137] Furthermore, the two edge arc segments of the outer side line are respectively denoted as the first arc segment 131 and the second arc segment 132, and the middle segment of the outer side line is an arc segment and is denoted as the middle arc segment 133. The first arc segment 131 and the second arc segment 132 are symmetric about the axis of symmetry, as Figures 2 to 6 shown, and the centers of the first arc segment 131 and the second arc segment 132 coincide, and the center of the middle arc segment 133 is located on the axis of symmetry.

[0138] This design makes the shape of the permanent magnet 10 more regular and the structure more symmetric, thus further reducing the processing difficulty and being conducive to further improving the processing efficiency of the permanent magnet 10.

[0139] For the case where the inner side line 121 is a complete arc, the air gap center is denoted as O, and the centers of the inner side line 121 (denoted as O2), the first arc segment 131 and the second arc segment 132 of the outer side line (denoted as O3), and the center of the middle arc segment 133 (denoted as O1) have the following five positional relationships:

[0140] 1) The centers of the first arc segment 131, the second arc segment 132 and the inner side line 121 coincide, and the center of the middle arc segment 133 deviates from the center of the inner side line 121, as Figure 2 shown.

[0141] In other words, O2 and O3 coincide and deviate from O1 and are not consistent with O1, as Figure 2 shown. This design enables the arc surface corresponding to the first arc segment 131 (denoted as the first side arc surface), the arc surface corresponding to the second arc segment 132 (denoted as the second side arc surface) and the inner side surface 120 (which can also be called the inner arc surface) to be processed by the same process, thus being conducive to improving the processing efficiency of the permanent magnet 10.

[0142] 2) The centers of the first arc segment 131, the middle arc segment 133 and the second arc segment 132 coincide, as Figure 6 shown, and the center of the outer side line deviates from the center of the inner side line 121.

[0143] In other words, O1 and O3 coincide and deviate from O2 and are not consistent with O2, as Figure 6 shown. This design enables the entire outer side surface 130 (which can also be called the outer arc surface) to be processed by the same process, thus being conducive to improving the processing efficiency of the permanent magnet 10.

[0144] 3) The center of the middle arc segment 133 and the center of the inner side line 121 coincide, and the center of the middle arc segment 133 deviates from the centers of the first arc segment 131 and the second arc segment 132, as Figure 5 shown.

[0145] In other words, O1 and O2 are consistent with each other and deviate from O3, being inconsistent with O3, as Figure 5 shown. Such a design enables the inner side surface 120 (which can also be referred to as the inner arc surface) and the middle arc line segment 133 (which can also be referred to as the middle surface) to be processed through the same process, thus facilitating the improvement of the processing efficiency of the permanent magnet 10.

[0146] 4) The centers of the first arc line segment 131, the middle arc line segment 133, the second arc line segment 132, and the inner side line 121 are consistent with each other, as Figure 4 shown.

[0147] In other words, O1, O2, and O3 are consistent with each other, as Figure 4 shown. Such a design enables the inner side surface 120 (which can also be referred to as the inner arc surface) and the entire outer side surface 130 (which can also be referred to as the outer arc surface) to be processed through the same process. The conventional disc-shaped permanent magnet 10 can be quickly formed by trimming the two side surfaces, reducing the processing difficulty and facilitating the improvement of the processing efficiency of the permanent magnet 10.

[0148] 5) The centers of the first arc line segment 131 and the second arc line segment 132, the center of the middle arc line segment 133, and the center of the inner side line 121 deviate from each other, as Figure 3 shown.

[0149] In other words, O1, O2, and O3 are all inconsistent with each other, as Figure 3 shown, and the specific shape of the permanent magnet 10 can be reasonably designed according to the specific requirements of the motor.

[0150] In any of the above embodiments, the first side line 111 and the edge arc line segment have a smooth transition, and the second side line 112 and the edge arc line segment have a smooth transition.

[0151] Such a design facilitates the processing and forming of the permanent magnet 10 and is conducive to improving the processing efficiency of the permanent magnet 10.

[0152] In any of the above embodiments, both the first side line 111 and the second side line 112 are straight line segments, and the extension lines of the first side line 111 and the second side line 112 intersect to form an included angle α. α and the number of pole pairs P of the rotor assembly 1 satisfy: α = 180° / P.

[0153] If the number of pole pairs of the rotor is P, then the number of permanent magnets 10 included in the rotor assembly 1 is twice that of P. Such a design facilitates the uniform arrangement of multiple permanent magnets 10 along the circumferential direction of the rotor assembly 1.

[0154] Furthermore, the intersection point of the extension lines of the first side line 111 and the second side line 112 is located on the symmetry axis and between the central axis and the inner side line 121, as Figures 2 to 6 shown.

[0155] Such a design is beneficial to further increase the end distance between two adjacent permanent magnets 10, thereby further improving the corner leakage magnetic flux and further enhancing the motor performance.

[0156] As Figure 11 As shown in the figure, the motor provided by the embodiment of the second aspect of the present invention includes: a stator assembly 102 and a rotor assembly 1 according to any one of the embodiments of the first aspect. The rotor assembly 1 is matched with the stator assembly 102 and is adapted to rotate relative to the stator assembly 102.

[0157] The motor 100 provided by the embodiment of the second aspect of the present invention includes the rotor assembly 1 according to any one of the embodiments of the first aspect, and thus has all the beneficial effects of any of the above embodiments, which will not be elaborated herein.

[0158] As Figure 12 As shown in the figure, the electrical equipment 200 provided by the embodiment of the third aspect of the present invention includes: a device main body 202 and a motor 100 according to the embodiment of the second aspect. The motor 100 is connected to the device main body 202.

[0159] Specifically, the motor 100 is an axial-flux permanent magnet motor 100, or a disc motor 100.

[0160] The electrical equipment 200 provided by the embodiment of the third aspect of the present invention includes the motor 100 according to the embodiment of the second aspect, and thus has all the beneficial effects of any of the above embodiments, which will not be elaborated herein.

[0161] In the above embodiments, the electrical equipment 200 may be, but is not limited to: compressors, fans, pumps, household appliances such as refrigerators and air conditioners, vehicles, industrial equipment such as multi-connected units, etc.

[0162] Some specific embodiments will be introduced below and compared with the prior art.

[0163] With the development of motor technology, permanent magnet brushless DC motors are widely used in various places in various fields. Disc permanent magnet brushless motors are gradually applied to various places with high requirements for structural volume, such as home appliances, vehicles, industry and other fields, due to their advantages of compact structure and small volume.

[0164] In the application of disc motors, the centrifugal force and the axial magnetic suction force between the stator and rotor of the motor make the permanent magnets prone to falling off, which has become a major problem restricting the application of disc motors. Generally, permanent magnets are bonded to the surface of the rotor core. However, the disadvantage of this traditional structure is that during the operation of the disc motor, the directly bonded permanent magnets are not firmly bonded, and the phenomenon of the whole or partial falling off occurs, which poses a great risk to the operation of the motor. There is also a way to press the permanent magnet with a whole pressing plate. The disadvantage of this structure is that the eddy current loss in the pressing plate is large, and because the pressing plate has a thickness, the air gap of the motor is increased, affecting the air gap magnetic density of the motor and the utilization rate of the permanent magnet.

[0165] As a power source, most of the permanent magnets in existing permanent magnet motors are fan-shaped or circular. The processing difficulty of fan-shaped permanent magnets is relatively large, and the magnetic leakage at the four corners is serious, resulting in serious local saturation of the motor rotor, making the back electromotive force harmonics, cogging torque and torque ripple of the motor relatively large, and the utilization rate of the inner side surface of the permanent magnet is not high. The processing of circular permanent magnets is relatively simple, but the overall utilization rate is not high, resulting in a relatively small back electromotive force of the motor and reducing the output capacity of the motor.

[0166] For this reason, the present invention proposes a rotor assembly 1 of a disc motor and a disc motor including the rotor assembly 1.

[0167] Specific Example 1

[0168] A rotor assembly 1 includes: a permanent magnet, a rotor core 20, a non-magnetic rotor disc 30, and a plastic-coated body 40 that integrally forms the sequentially arranged permanent magnet, rotor core 20, and rotor disc 30. The permanent magnet includes an upper surface, a lower surface, an inner arc surface, an outer arc surface, and two side surfaces.

[0169] Wherein, in the projection of the permanent magnet on its upper surface or lower surface, the inner arc surface is composed of an arc, and the center of the arc forming the inner arc surface is not consistent with the center of the air gap. The outer arc surface is composed of a left side surface, a right side surface, and a middle surface. The left side surface and the right side surface are symmetric about the middle surface, and their centers are the same. The center of the middle surface is located on the central symmetry line of the permanent magnet.

[0170] Specifically, for the convenience of understanding with the accompanying drawings, the two end faces of the permanent magnet are called the upper surface and the lower surface; the inner side surface 120 of the permanent magnet is called the inner arc surface, and the radii of the inner side surfaces 120 are the same; the outer side surface 130 of the permanent magnet is called the outer arc surface, and the surfaces corresponding to the first arc segment 131, the middle arc segment 133, and the second arc segment 132 of the outer arc surface are respectively simply called the left side surface, the middle surface, and the right side surface; the first side surface 11 and the second side surface 110 of the permanent magnet are simply called the two side surfaces.

[0171] For the disc motor according to the present invention, the unique design of the permanent magnet is convenient for processing compared with the conventional sector-shaped magnetic tiles, reduces the magnetic leakage at the corners, makes the air gap sinusoidal, reduces the back electromotive force harmonics, cogging torque and torque ripple. The non-magnetic rotor disc 30 and the integrally plastic-coated structure enhance the rotor structural strength, are beneficial to overcoming the centrifugal force during rotor rotation, prevent the permanent magnet 10 from falling off, and at the same time reduce the axial deformation of the rotor. The non-magnetic rotor disc 30, on the basis of not causing additional losses, on the one hand, is beneficial to ensuring the overall strength of the rotor and the flatness of the plane in contact with the rotor core 20, and on the other hand, ensures the reliability of the operation of the rotor assembly 1 by connecting the rotor disc 30 to the motor shaft.

[0172] Furthermore, the upper surface or the lower surface of the permanent magnet is surface-mounted on the rotor core 20, and a plurality of permanent magnets are arranged concentrically with the rotor core 20. The design of the surface-mounted permanent magnet 10 simplifies the process difficulty.

[0173] Furthermore, the plastic-coated component forms an integral body of the sequentially arranged permanent magnets, rotor core 20, and rotor disc 30, and the upper surface or the lower surface of the permanent magnet on the non-surface-mounted rotor core 20 side protrudes from the end face of the plastic-coated component.

[0174] Adopting an additional plastic-coated form to fixedly connect the permanent magnet and the rotor core 20 together avoids the risk of the surface-bonded permanent magnet being not firmly bonded and causing the whole or partial detachment, improving the reliability of the motor operation. In addition, the design form of integrally plastic-coating all rotor components enhances the overall strength of the rotor structure, is beneficial to overcoming the centrifugal force during the rotation of the rotor disc 30, reduces the axial deformation of the rotor caused by the axial magnetic field operation of the rotor, which affects the air gap uniformity of the motor and the sinusoidality of the air gap magnetic density of the motor, and is beneficial to ensuring the sinusoidality of the back electromotive force and reducing the cogging torque and torque ripple of the motor. The end face of the permanent magnet opposite to the air gap protrudes from the end face of the plastic-coated body 40, which is beneficial to ensuring the design of a small air gap of the motor, thereby reducing the usage amount of the permanent magnet 10, improving the utilization rate of the permanent magnet 10, and increasing the power density of the motor.

[0175] Furthermore, the rotor core 20 is formed by axially laminating silicon steel sheets, and there is an inner groove 21 at the inner radius of the rotor core 20 and an outer groove 22 at the outer radius. Compared with the conventional integral iron core rotor, the rotor core 20 adopting the silicon steel sheet design is beneficial to reducing the eddy current loss in the rotor disc 30 and improving the operation efficiency of the motor.

[0176] Furthermore, the rotor core 20 is welded into an integral structure by using the outer groove 22 of the rotor core 20. At the same time, the outer groove 22 increases the contact surface of the plastic-coated structure, which is beneficial to enhancing the connection strength between the injection-molded component and other rotor parts.

[0177] Further, there is a through hole 31 on the inner side surface 120 of the rotor disk 30, and the through hole 31 corresponds to the position of the inner groove 21 in the rotor core 20, which facilitates connecting the rotor disk 30 and the rotor core 20 together during plastic coating.

[0178] Further, the center of the arc forming the inner arc surface of the permanent magnet is located on the central symmetry line of the permanent magnet. Therefore, the inner arc surface can be integrally formed. When the center of the inner arc surface and the center of the air gap are on both sides of the inner arc surface, the inner arc surface presents a shape that bulges and approaches the center of the air gap; when the center of the inner arc surface and the center of the air gap are on the same side of the inner arc surface, the inner arc surface presents a shape that bulges and moves away from the center of the air gap. It can be applied according to actual application conditions.

[0179] Among them, when the center of the inner arc surface is located outside the permanent magnet, the distance between the ends of two adjacent permanent magnets increases at this time, reducing the magnetic leakage between their corners, which is beneficial to improving the utilization rate of the permanent magnet.

[0180] Further, the centers of the left side surface and the right side surface of the permanent magnet are the same as the center of the arc forming the inner arc surface, as Figure 2 shown. Therefore, the left side surface, the right side surface and the inner arc surface of the permanent magnet can be processed by the same process, which is beneficial to improving the processing efficiency of the permanent magnet.

[0181] Specific Example 2

[0182] The difference from Specific Example 1 is that: the centers of the left side surface, the right side surface and the middle surface of the permanent magnet are the same, as Figure 6 shown. At this time, the outer arc surface of the formed permanent magnet can be integrally formed, reducing the processing difficulty and the number of processing steps, which is beneficial to improving the processing efficiency of the permanent magnet.

[0183] Specific Example 3

[0184] The difference from Specific Example 1 is that: the centers of the left side surface, the right side surface, the middle surface of the permanent magnet are the same as the center of the arc forming the inner arc surface, as Figure 4 shown. At this time, the permanent magnet can be quickly formed by trimming the two side surfaces of a conventional disc-shaped permanent magnet, reducing the processing difficulty, which is beneficial to improving the processing efficiency of the permanent magnet.

[0185] Specific Example 4

[0186] The difference from Specific Example 1 is that: the center of the middle surface of the permanent magnet is the same as the center of the inner arc surface, as Figure 5 shown. Therefore, the middle surface and the inner arc surface of the permanent magnet can be processed by the same process, which is beneficial to improving the processing efficiency of the permanent magnet.

[0187] Specific Example 5

[0188] The difference from Specific Example 1 is that: the centers of the left side surface, the right side surface and the middle surface of the permanent magnet are the same, and the center of the middle surface is also different from the center of the inner arc surface, asFigure 3 as shown

[0189] The inner side 120 and the outer side 130 of the above-mentioned permanent magnet both adopt an optimized arc shape. On the one hand, it is beneficial to increase the distance between the ends of two adjacent permanent magnets, reduce the magnetic leakage between their corners, and improve the utilization rate of the permanent magnet on the basis of reducing the usage amount of the permanent magnet 10. On the other hand, the optimized arc design is beneficial to sinusoidalization of the air-gap magnetic field, reduce back-EMF harmonics, cogging torque and torque ripple.

[0190] In some embodiments, the two side surfaces of the permanent magnet are smoothly transitioned with the left side surface, the right side surface, and the inner arc surface, which is beneficial to the processing of the permanent magnet.

[0191] In some embodiments, the angle between the two side surfaces of the permanent magnet is α, and α = 360 / (2×P), where P is the number of pole pairs.

[0192] In the present invention, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. Terms such as "installation", "connection", "connection", and "fixation" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. 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.

[0193] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation to the present invention.

[0194] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0195] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rotor assembly, characterized in that, For an axial flux permanent magnet motor or a disc motor, comprising: A rotor core, the rotor core being of an annular structure; A permanent magnet, one axial end face of the permanent magnet being connected to one axial end face of the rotor core; A rotor disc, the rotor disc being made of a non-magnetic material, the rotor disc being connected to the other axial end face of the rotor core; A plastic-coated body, the plastic-coated body covering at least a part of the rotor core, at least a part of the permanent magnet, and at least a part of the rotor disc, so that the rotor core, the permanent magnet, and the rotor disc form an integral structure; The permanent magnet includes: Two end faces; and A side circumferential surface, the side circumferential surface including a first side surface, an outer side surface, a second side surface, and an inner side surface that are sequentially connected end to end. The projections of the first side surface, the outer side surface, the second side surface, and the inner side surface on the end face are respectively a first side line segment, an outer side line segment, a second side line segment, and an inner side line segment. The projection of the side circumferential surface on the end face is an axisymmetric structure. The connection line between the midpoints of the inner side line segment and the outer side line segment forms the axis of symmetry of the axisymmetric structure, and the axis of symmetry is configured to be perpendicular to and intersect with the central axis of the rotor assembly of the motor; Wherein, both the inner side line segment and the outer side line segment include two edge arc segments and an intermediate segment located between the two edge arc segments. The centers of the two edge arc segments of the inner side line segment and / or the centers of the two edge arc segments of the outer side line segment are located between the central axis and the outer side line segment; Both the first side line segment and the second side line segment are straight line segments. The extension lines of the first side line segment and the second side line segment intersect to form an included angle α, and α satisfies the following relationship with the number of pole pairs P of the rotor assembly: α = 180° / P; The intersection point of the extension lines of the first side line segment and the second side line segment is located on the axis of symmetry and between the central axis and the inner side line segment; The projection of the central axis of the rotor assembly on the end face of the permanent magnet is denoted as the air gap center of the motor. The center of the edge arc segment deviates from the air gap center and is not consistent with the air gap center.

2. The rotor assembly according to claim 1, wherein: The rotor core is formed by laminating silicon steel sheets along the axial direction of the rotor core.

3. The rotor assembly according to claim 2, wherein: The rotor core is an integrally formed structure by welding.

4. The rotor assembly according to any one of claims 1 to 3, wherein: The number of the permanent magnets is multiple. The multiple permanent magnets are attached to the rotor core, and the multiple permanent magnets are arranged in a circular array around the central axis of the rotor core.

5. The rotor assembly according to any one of claims 1 to 3, wherein: The end face of the permanent magnet away from the rotor core protrudes from the plastic-coated body.

6. The rotor assembly according to any one of claims 1 to 3, wherein: An outer groove is provided on the outer side surface of the rotor core. The plastic-coated body has an outer protrusion adapted to the outer groove, and the outer protrusion is embedded in the outer groove; and / or The inner side surface of the rotor core is provided with an inner groove, the plastic-coated body has an inner protrusion adapted to the inner groove, and the inner protrusion is embedded in the inner groove.

7. The rotor assembly according to claim 6, wherein The rotor disc is of an annular structure, the inner side surface of the rotor disc is provided with a through hole, the through hole corresponds to the inner groove of the rotor core, the plastic-coated body has a connecting column, and the connecting column is embedded in the through hole and the inner groove.

8. The rotor assembly according to any one of claims 1 to 3, wherein The middle section of the inner side line is an arc section.

9. The rotor assembly according to claim 8, wherein The center of the middle section of the inner side line coincides with the centers of the two edge arc sections of the inner side line.

10. The rotor assembly according to claim 9, wherein The center of the inner side line is located on the axis of symmetry.

11. The rotor assembly according to claim 8, wherein The inner side line is bent and protruded away from the outer side line; or The inner side line is bent and protruded towards the outer side line.

12. The rotor assembly according to any one of claims 1 to 3, wherein The two edge arc sections of the outer side line are respectively denoted as a first arc section and a second arc section, the middle section of the outer side line is an arc section and is denoted as a middle arc section, the first arc section and the second arc section are symmetrical about the axis of symmetry, and the centers of the first arc section and the second arc section coincide, and the center of the middle arc section is located on the axis of symmetry.

13. The rotor assembly according to claim 12, wherein The centers of the first arc section, the second arc section and the inner side line coincide, and the center of the middle arc section deviates from the center of the inner side line; or The centers of the first arc section, the middle arc section and the second arc section coincide, and the center of the outer side line deviates from the center of the inner side line; or The center of the middle arc section coincides with the center of the inner side line, and the center of the middle arc section deviates from the centers of the first arc section and the second arc section; or The centers of the first arc section, the middle arc section, the second arc section and the inner side line coincide; or The centers of the first arc section and the second arc section, the center of the middle arc section and the center of the inner side line deviate from each other.

14. The rotor assembly according to any one of claims 1 to 3, wherein There is a smooth transition between the first side line and the edge arc section; There is a smooth transition between the second side line and the edge arc section.

15. A motor, characterized in that, Comprising: A stator assembly; And The rotor assembly according to any one of claims 1 to 14, the rotor assembly is matched with the stator assembly and is adapted to rotate relative to the stator assembly.

16. An electrical device, characterized in that, Comprising: An equipment main body; And The motor according to claim 15, the motor is connected to the equipment main body.

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