Motor and household appliance

Abstract

The present application discloses a motor and a household appliance. The motor comprises a rotor assembly (100) and a stator assembly. The rotor assembly (100) comprises a plurality of outer core units (110) and a plurality of permanent magnets (120). On a projection plane perpendicular to the axis of rotation, the projection of the outer contour of each outer core unit (110) comprises a second arc-shaped segment (1112), a first arc-shaped segment (1111), and a fifth arc-shaped segment (1113) which are sequentially connected. In a direction away from the first arc-shaped segment (1111), the distance between the second arc-shaped segment (1112) and the axis of rotation progressively decreases, and the distance between the fifth arc-shaped segment (1113) and the axis of rotation progressively decreases. A stator core (200) comprises a plurality of stator units (220) arranged in the circumferential direction. Each stator unit (220) comprises a yoke portion (240), a tooth portion (221), and a shoe portion (222). The yoke portion (240) and the shoe portion (222) are connected to both ends of the tooth portion (221) in the radial direction, respectively. A radial outer wall surface and a radial inner wall surface of the yoke portion (240) are parallel planes. Each two adjacent yoke portions (240) are connected. A winding slot (230) is defined between each two adjacent stator units (220). A slot opening (231) of a winding slot (230) is defined between each two adjacent shoe portions (222).

Description

Motor and household appliance

[0001] Cross-reference to related applications

[0002] The present application claims priority to Chinese Patent Application No. 202410529176.X, filed on April 29, 2024, and entitled “Motor and Household Appliance”, and Chinese Patent Application No. 202420925307.1, filed on April 29, 2024, and entitled “Motor and Household Appliance”, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of electrical equipment, in particular to a motor and a household appliance. BACKGROUND

[0004] For a clothes treatment device, such as a washing machine, a clothes dryer, etc., a motor provided inside the clothes treatment device serves as a core component of the clothes treatment device, and the performance of the motor plays a key role in the use performance of the clothes treatment device. In the related art, generally speaking, the running speed of the motor in the clothes treatment device is relatively high. Due to the existence of the stator slot opening and the large air gap magnetic field harmonic between the stator and the rotor, the vibration of the stator and the rotor is relatively large during the high-speed running of the motor, which produces relatively large noise and affects the performance of the motor. SUMMARY

[0005] The present application aims to at least partially solve one of the technical problems existing in the prior art. To this end, the present application proposes a motor capable of reducing harmonic components in the air gap magnetic field, and a household appliance having the above motor.

[0006] According to the motor of the first aspect of the present application, the motor comprises a rotor assembly rotating around a rotation axis, the rotor assembly comprising a plurality of outer core units and a plurality of permanent magnets, the plurality of outer core units being arranged at intervals along a circumferential direction of the rotor assembly, two adjacent outer core units defining a mounting groove therebetween, and the plurality of permanent magnets being correspondingly mounted in the plurality of mounting grooves; in a projection plane perpendicular to the rotation axis, a projection of an outer contour of the outer core unit comprises a second arc segment, a first arc segment and a fifth arc segment connected in sequence, a distance between the second arc segment and the rotation axis decreases in a direction away from the first arc segment, and a distance between the fifth arc segment and the rotation axis decreases in the direction away from the first arc segment; and a stator assembly comprising a stator core arranged around an outer periphery of the rotor assembly, the stator core comprising a plurality of stator units arranged along the circumferential direction, each stator unit comprising a yoke portion, a tooth portion and a shoe portion, the yoke portion and the shoe portion being respectively connected to two radial ends of the tooth portion, a radial outer wall surface and a radial inner wall surface of the yoke portion being parallel planes, two adjacent yoke portions being connected, and a wire winding groove being defined between two adjacent stator units, and a slot opening of the wire winding groove being defined between two adjacent shoe portions.

[0007] According to some embodiments of the present application, the second arc segment and the fifth arc segment are symmetrically arranged.

[0008] According to some embodiments of the present application, along the circumferential direction, a minimum width of the slot opening is W1, a central angle corresponding to the first arc segment is θ1, and a central angle corresponding to the second arc segment is θ2, and the following condition is satisfied: 0.615≤W1*θ1 / θ2≤2.

[0009] According to some embodiments of the present application, the minimum width W1 of the slot opening and the central angle θ2 corresponding to the second arc segment satisfy the following condition: 0.0405≤W1 / θ2≤0.1.

[0010] According to some embodiments of the present application, the central angle θ1 corresponding to the first arc segment and the central angle θ2 corresponding to the second arc segment satisfy the following condition: 0.41≤θ1 / θ2≤0.572.

[0011] According to some embodiments of the present application, along the circumferential direction, the shoe portion is protrudingly arranged towards two sides of the tooth portion, and a minimum width of the shoe portion along the circumferential direction is W2, and the following condition is satisfied: 0.088≤W1 / W2≤0.234.

[0012] According to some embodiments of the present application, in the projection plane perpendicular to the rotation axis, a projection of an inner contour of the shoe portion comprises a third arc segment and a fourth linear segment connected to two ends of the third arc segment respectively, and a distance between the fourth linear segment and the rotation axis increases in a direction away from the third arc segment.

[0013] According to some embodiments of the present application, the rotor assembly has an outer peripheral wall, and the stator assembly has an inner peripheral wall, and there is an air gap between the outer peripheral wall of the rotor assembly and the inner peripheral wall of the stator assembly, the minimum distance of the air gap is L1, and the maximum distance of the air gap is L2, and the following condition is met: 0.107≤L1 / L2≤0.25.

[0014] According to some embodiments of the present application, the number of the outer iron core units is N, and the maximum outer diameter of the rotor assembly is D3, and the following condition is met: 0.01≤L1*N / (π*D3)≤0.025.

[0015] According to some embodiments of the present application, the minimum distance L1 of the air gap meets the following condition: 0.3mm≤L1≤0.6mm.

[0016] According to some embodiments of the present application, the outer iron core unit is provided with a magnetic barrier hole, and the projection of the magnetic barrier hole on a projection plane perpendicular to the rotation axis is in a strip shape and has a length direction, and the two ends of the magnetic barrier hole along the length direction are respectively directed towards the mounting groove and the outer contour of the outer iron core unit.

[0017] According to some embodiments of the present application, the number of the magnetic barrier holes of each outer iron core unit is two, and the two magnetic barrier holes are symmetrically arranged about a first symmetry center line of the outer iron core unit, and the included angle of the two magnetic barrier holes is θ3, and the following condition is met: 0.033≤W1 / θ3≤0.14.

[0018] According to some embodiments of the present application, the minimum width W1 of the notch, the central angle θ1 corresponding to the first arc-shaped segment, and the included angle θ3 of the two magnetic barrier holes meet the following condition: 0.49≤W1*θ1 / θ3≤5.58.

[0019] According to some embodiments of the present application, from the middle of the permanent magnet to the two ends of the permanent magnet in the radial direction, the distance between the two wall surfaces of the permanent magnet facing away from each other in the circumferential direction decreases.

[0020] According to some embodiments of the present application, the maximum outer diameter of the stator assembly is D1, and the minimum inner diameter of the stator assembly is D2, and the following condition is met: 0.58≤D2 / D1≤0.625.

[0021] According to some embodiments of the present application, the outer iron core unit comprises a second limiting protrusion, the second limiting protrusion is located at one end of the mounting groove away from the rotation axis, and the second limiting protrusion comprises a fixing portion, the fixing portion is located at one end of the second limiting protrusion away from the mounting groove and protrudes along the circumferential direction.

[0022] According to some embodiments of the present application, the rotor assembly further comprises a first plastic covering member covering the outer core unit and the permanent magnet, and the stator assembly further comprises a second plastic covering member covering the stator core.

[0023] According to the household appliance of the second aspect of the present application, the motor comprises the motor of the first aspect of the present application.

[0024] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be further described below in conjunction with the accompanying drawings and embodiments, in which:

[0026] Fig. 1 is an axial schematic view of a motor according to an embodiment of the present application;

[0027] Fig. 2 is an enlarged view of A in Fig. 1;

[0028] Fig. 3 is an axial schematic view of a rotor core according to an embodiment of the present application;

[0029] Fig. 4 is an enlarged view of B in Fig. 3;

[0030] Fig. 5 is an axial schematic view of a stator core according to an embodiment of the present application;

[0031] Fig. 6 is an enlarged view of C in Fig. 5;

[0032] Fig. 7 is a schematic view of a stator core according to an embodiment of the present application, which is unfolded into a straight strip;

[0033] Fig. 8 is a partial axial schematic view of an outer core unit according to another embodiment of the present application; and

[0034] Fig. 9 is a columnar schematic view of the radial acceleration of the technical solution of the present application compared with the prior art solution.

[0035] Label: rotor assembly 100; outer core unit 110; first wall surface 111; first arc segment 1111; second arc segment 1112; fifth arc segment 1113; magnetic barrier hole 112; second limiting protrusion 113; through hole 114; fixed part 115; permanent magnet 120; mounting groove 130; second wall surface 131; third wall surface 132; air gap 140; inner core 150; shaft hole 151; first limiting protrusion 152; stator core 200; stator unit 220; tooth part 221; shoe part 222; fourth wall surface 2221; third arc segment 2222; fourth line segment 2223; fifth wall surface 2224; sixth wall surface 2225; winding slot 230; slot opening 231; yoke part 240; rivet buckle part 250; first reference point K; first center line of symmetry Z1; second center line of symmetry Z2; first reference circle P1; second reference circle P2. DETAILED DESCRIPTION

[0036] The embodiments of the present application are described below in detail with reference to the accompanying drawings. In the drawings, the same or similar elements have the same or similar reference numbers throughout the drawings. The embodiments described below are examples for explaining the present application and are not intended to limit the present application.

[0037] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the purpose of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0038] In the description of the present application, the meaning of several is one or more, and the meaning of multiple is two or more. Greater than, less than, more than, etc. are understood to not include the number itself, and above, below, etc. are understood to include the number itself. If it is described as first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of technical features indicated.

[0039] In the description of the present application, unless otherwise explicitly limited, the words such as setting, mounting, connecting, assembling, cooperating, etc. should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0040] For a clothes treatment device such as a washing machine, a clothes dryer, etc., a motor arranged inside the clothes treatment device serves as a core component of the clothes treatment device, and the performance of the motor plays a key role in the use performance of the clothes treatment device. Currently, the requirements for the performance and cost performance of the motor are gradually increasing. In the related art, generally, the running speed of the motor in the clothes treatment device is relatively high. Due to the existence of the stator slot, the motor has torque ripple, and the air gap magnetic field harmonic between the stator and the rotor is relatively large. Some of the harmonics will cause noise, and some of the harmonics will cause the back electromotive force waveform to be distorted. During high-speed operation of the motor, the vibration of the stator and the rotor is relatively large, which will generate relatively large noise, affecting the performance of the motor.

[0041] To this end, with reference to FIGS. 1-9, the first aspect of the present application provides a motor applied to a household appliance such as a washing machine, a clothes dryer, etc. The motor drives the rotation of the drum of the washing machine or the clothes dryer.

[0042] As shown in FIGS. 1 and 2, it can be understood that the motor includes a rotor assembly 100 and a stator assembly. In this embodiment, the motor is an inner rotor motor, that is, the stator assembly is arranged around the outer periphery of the rotor assembly 100, or in other words, the stator assembly has an inner cavity, and the rotor assembly 100 is accommodated in the inner cavity. And the rotor assembly 100 can rotate relative to the stator assembly, and the central axis of the rotor assembly 100 itself is the rotation axis.

[0043] As shown in FIGS. 1 and 3, it can be understood that the rotor assembly 100 includes a rotor core. Specifically, in terms of composition, the rotor core is composed of a plurality of rotor laminations arranged in correspondence with layers in the direction of the rotation axis. Generally, each rotor lamination has the same structure, which facilitates processing, reduces the number of molds, and reduces production costs. The rotor lamination generally includes an annular lamination monomer and a plurality of sector lamination monomers connected to the outer periphery of the annular lamination monomer and arranged at equal intervals along the circumferential direction of the annular lamination monomer. The annular lamination monomer and the plurality of sector lamination monomers are an integral structure. The circumferential direction is the direction around the rotation axis.

[0044] Referring to FIGS. 1 and 3, it can be understood that, in terms of overall structure, the rotor core includes an inner core 150 corresponding to annular core pieces of the rotor core piece and a plurality of outer core units 110 corresponding to sector core pieces of the rotor core piece. Specifically, the outer core units 110 are connected to the outer periphery of the inner core 150, and the plurality of outer core units 110 are arranged at equal intervals along the circumferential direction of the inner core 150. The inner core 150 is provided with a shaft hole 151 penetrating in the direction of the rotation axis, and the rotating shaft of the motor is arranged through the shaft hole 151 and fixedly connected with the rotor core, for example, the rotating shaft of the motor is in interference fit with the rotor core. In the projection plane perpendicular to the rotation axis, the projection of the outer core unit 110 is substantially sector-shaped, and the projection of the inner core 150 is substantially annular.

[0045] Referring to FIGS. 1 and 3, it can be understood that the rotor assembly 100 further includes a plurality of permanent magnets 120. Specifically, two adjacent outer core units 110 and the inner core 150 define a mounting groove 130 therebetween, and it can be easily understood that the number of mounting grooves 130, the number of permanent magnets 120 and the number of outer core units 110 are equal, and in the embodiment, the number of mounting grooves 130, the number of permanent magnets 120 and the number of outer core units 110 are all eight. The mounting groove 130 penetrates the rotor core in the direction of the rotation axis. The plurality of permanent magnets 120 are correspondingly accommodated in the plurality of mounting grooves 130, so as to realize mounting of the permanent magnets 120 into the rotor core.

[0046] Referring to FIGS. 1 and 4, it can be understood that, in order to improve the structural strength of the rotor assembly 100, the rotor assembly 100 further includes a first plastic package, and the first plastic package is wrapped on the outer core unit 110 and the permanent magnet 120. Specifically, each outer core unit 110 is further provided with a through hole 114 penetrating the rotor core in the direction of the rotation axis, and the first plastic package is filled into the through hole 114 and the gap between the permanent magnet 120 and the inner wall of the mounting groove 130, and at the same time, the first plastic package covers the two end wall surfaces of the permanent magnet 120 in the direction of the rotation axis, so as to make the rotor assembly 100 more integrated, high in structural strength, and more reliable in structure, avoid loosening of the permanent magnet 120, and reduce magnetic leakage.

[0047] Referring to FIG. 1 and FIG. 4, it can be understood that the inner core 150 includes a first limiting protrusion 152, which is located on the outer circumferential wall of the inner core 150 and protrudes towards the center of the mounting groove 130, and the first limiting protrusion 152 corresponds to the mounting groove 130 one by one. In addition, each outer core unit 110 includes two second limiting protrusions 113, which are located on the outer end of the outer core unit 110 and respectively protrude towards the two sides of the outer core unit 110 along the circumferential direction of the rotor core, that is, the second limiting protrusion 113 is located at one end of the mounting groove 130 away from the rotation axis, and the outer end of the mounting groove 130 along the two sides of the circumferential direction of the rotor core has the second limiting protrusion 113. Here, "outer" means the direction away from the rotation axis, and the opposite direction is "inner". The permanent magnet 120 is installed in the mounting groove 130, and the first limiting part and the second limiting part respectively abut the two ends of the permanent magnet 120 along the radial direction of the rotor core, that is, the direction perpendicular to the rotation axis, so that the permanent magnet 120 is installed stably, avoiding the loosening of the permanent magnet 120 during the rotation of the rotor assembly 100, which causes demagnetization or vibration, noise and other disadvantages of the permanent magnet 120, and is beneficial to improve the performance of the motor.

[0048] Referring to FIG. 2 and FIG. 4, it can be understood that the second limiting protrusion 113 includes a fixed part 115, which is located at the outer end of the second limiting protrusion 113, that is, the fixed part 115 is located at one end of the second limiting protrusion 113 away from the mounting groove 130, and the fixed part 115 protrudes along the circumferential direction of the rotor core, that is, it is located in the two second limiting protrusions 113 on the two sides of the circumferential direction of the rotor core of the mounting groove 130, and the two fixed parts 115 protrude towards the opposite direction. Generally, the first plastic package of the rotor assembly 100 will fill the space between the two second limiting protrusions 113 on the two sides of the circumferential direction of the rotor core of the mounting groove 130, and thus the fixed part 115 is inserted or embedded in the first plastic package, which fixes the first plastic package, reduces the risk of the first plastic package separating from the rotor core under the action of centrifugal force during the rotation of the rotor assembly 100, and makes the structure of the first plastic package more stable.

[0049] Referring to FIG. 5 and FIG. 7, it can be understood that the stator assembly includes a stator core 200 and a winding, specifically, the stator core 200 includes a plurality of stator units 220, which are connected in sequence and surround a ring shape, so that the ring structure surrounded by the plurality of stator units 220 forms an inner cavity capable of accommodating the rotor assembly 100.

[0050] Referring to FIGS. 5 and 6, it can be understood that in the stator core 200, the plurality of stator units 220 are arranged equidistantly along the circumferential direction of the stator core 200, and a winding slot 230 is defined between each two adjacent stator units 220. Each winding slot 230 penetrates the stator core 200 along the direction of the rotation axis, and the number of winding slots 230 is equal to the number of stator units 220. The stator unit 220 comprises a yoke portion 240, a tooth portion 221 and a shoe portion 222. The tooth portion 221 is arranged along the radial direction of the stator core 200, and one end of the tooth portion 221 is connected to the yoke portion 240. The shoe portion 222 is connected to the other end of the tooth portion 221. The yoke portion 240 is located at the end of the tooth portion 221 away from the rotation axis, and the shoe portion 222 is located at the end of the tooth portion 221 close to the rotation axis. The two adjacent yoke portions 240 are connected, and the connection is a partial structure, for example, the two yoke portions 240 are adjacent only at the outer ends, so that the two adjacent stator units 220 can swing relative to each other. The radial outer wall surface and the radial inner wall surface of the yoke portion 240 are parallel planes, so that the plurality of stator units 220 can be expanded into a straight strip or surrounded into a ring, that is, the stator core 200 is a block structure. Along the circumferential direction of the stator core 200, the shoe portion 222 is protrudingly arranged towards both sides of the tooth portion 221. Therefore, a slot opening 231 is formed between the two adjacent shoe portions 222, and the slot opening 231 is in communication with the winding slot 230 and faces the rotor assembly 100. The winding is wound on the tooth portion 221. When winding, the winding nozzle extends into the winding slot 230 through the slot opening 231 to perform winding, which is convenient to operate.

[0051] Of course, in other embodiments, the two yoke portions 240 in the two adjacent stator units 220 can be connected by the cooperation of the shaft pin and the pin hole, so that the two adjacent stator units 220 can also swing relative to each other, and the plurality of stator units 220 can be expanded into a straight strip or surrounded into a ring, which will not be described here.

[0052] Referring to FIGS. 5 and 7, it can be understood that from the composition, the stator core 200 is also composed of a plurality of stator laminations arranged in layers corresponding to the direction of the rotation axis. Since the stator core 200 is a block structure and can be expanded into a straight strip, when the stator core 200 is produced, the straight strip-shaped stator laminations can be first machined, then the plurality of straight strip-shaped stator laminations are sequentially stacked and fixed, and then surrounded into a ring to obtain the stator core 200. The straight strip-shaped stator laminations are beneficial to optimize the layout on the sheet material, so as to fully utilize the sheet material, reduce waste, improve the utilization rate of the sheet material, and reduce the production cost.

[0053] Referring to FIGS. 5 and 6, it can be understood that, in order to improve the structural strength of the stator core 200, the portion corresponding to each yoke portion 240 and the portion corresponding to each tooth portion 221 in each stator punching sheet are provided with rivet portions 250, and two adjacent stator punching sheets are connected and fixed through the rivet portions 250, so that the overall structural strength of the stator core 200 can be increased, and the structure is more reliable.

[0054] Referring to FIGS. 5 and 7, it can be understood that, in each stator unit 220, the side wall surface of the yoke portion 240 away from the stator unit 220 is a plane, that is, the outer wall surface of the yoke portion 240 is a plane, and when the plurality of stator units 220 are unfolded into a straight strip shape, the outer wall surfaces of the plurality of yoke portions 240 are on the same plane. Therefore, when the stator punching sheet is punched, the wall surface of the stator punching sheet corresponding to the outer wall surfaces of the plurality of yoke portions 240 is on the same plane, so that the layout mode on the sheet metal can be further optimized to fully utilize the sheet metal, reduce waste, improve the utilization rate of the sheet metal, and reduce production costs.

[0055] Referring to FIG. 5, it can be understood that, after the plurality of stator units 220 are arranged around the annular stator core 200, the projection of the outer peripheral wall of the stator core 200 on the projection plane perpendicular to the rotation axis is a regular polygon. In this embodiment, the stator core 200 includes twelve stator units 220, and the projection of the outer peripheral wall of the stator core 200 is a regular dodecagon.

[0056] Referring to FIGS. 1 and 2, it can be understood that the inner peripheral wall of the stator assembly and the outer peripheral wall of the rotor assembly 100 are arranged at intervals and form an air gap 140 therebetween. Generally, the stator assembly includes a second plastic covering member covering the stator core 200 to increase the overall structural stability of the stator assembly, but the second plastic covering member does not cover the inner peripheral wall of the stator core 200, that is, the inner peripheral wall of the stator core 200 is the inner peripheral wall of the stator assembly. Similarly, the first plastic covering member on the rotor assembly 100 does not cover the outer peripheral wall of the rotor core, and the outer peripheral wall of the rotor core is the outer peripheral wall of the rotor assembly 100. That is, the air gap 140 is located between the inner peripheral wall of the stator core 200 and the outer peripheral wall of the rotor core.

[0057] Referring to FIG. 2 and FIG. 6, it can be understood that the two opposite walls defining the two adjacent shoe portions 222 are respectively a fifth wall surface 2224 and a sixth wall surface 2225, that is, the fifth wall surface 2224 and the sixth wall surface 2225 are respectively two inner walls of the slot 231 oppositely arranged in the circumferential direction of the stator core. The minimum width of the slot 231 is defined as W1, and in this embodiment, the fifth wall surface 2224 and the sixth wall surface 2225 are parallel, so the perpendicular distance between the fifth wall surface 2224 and the sixth wall surface 2225 is the minimum width W1 of the slot 231. When measuring W1, the vernier caliper can be directly clamped between the fifth wall surface 2224 and the sixth wall surface 2225 for measurement. The unit of the minimum width W1 of the slot 231 is mm.

[0058] In other embodiments, the fifth wall surface 2224 and the sixth wall surface 2225 are not parallel, and the distance between the fifth wall surface 2224 and the sixth wall surface 2225 is measured at the minimum point.

[0059] Referring to FIG. 4, it can be understood that the outer side wall of the outer core unit 110 is defined as the first wall surface 111, that is, the first wall surface 111 is the wall surface of the side of the outer core unit 110 away from the rotation axis, that is, the first wall surface 111 is the outer contour of the outer core unit 110, and the first wall surface 111 is also part of the outer circumferential wall of the rotor core. In the projection plane perpendicular to the rotation axis, the projection of the rotation axis is defined as the first reference point K, and the projection of the first wall surface 111 includes the second arc segment 1112, the first arc segment 1111 and the fifth arc segment 1113 connected in turn. The outer core unit 110 has a first symmetry center line Z1 arranged in the radial direction of the rotor core, and the first symmetry center line Z1 passes through the first reference point K. The first arc segment 1111 intersects the first symmetry center line Z1 and is symmetrically arranged about the first symmetry center line Z1. The second arc segment 1112 extends in the circumferential direction of the rotor core and away from the first arc segment 1111, and similarly, the fifth arc segment 1113 extends in the circumferential direction of the rotor core and away from the first arc segment 1111. The second arc segment 1112 and the fifth arc segment 1113 are symmetrically arranged about the first symmetry center line Z1, that is, the projection of the first wall surface 111 is symmetric about the first symmetry center line Z1.

[0060] Referring to FIGS. 3 and 4, it can be understood that, in the embodiment, the first arc-shaped section 1111 is a circular arc section, and the center of the reference circle on which the first arc-shaped section 1111 is located coincides with the first reference point K. The second arc-shaped section 1112 and the fifth arc-shaped section 1113 are also circular arc sections, and the center of the reference circle on which the second arc-shaped section 1112 is located deviates from the first reference point K, and the center of the reference circle on which the fifth arc-shaped section 1113 is located deviates from the first reference point K. In the direction away from the first arc-shaped section 1111, the distance between the second arc-shaped section 1112 and the first reference point K decreases. A circle with the maximum outer diameter of the rotor core as the diameter and with the center of the circle located at the first reference point K is defined as a first reference circle P1. Generally, the maximum outer diameter of the rotor core is twice the maximum distance between the first arc-shaped section 1111 and the first reference point K, that is, the radius of the first reference circle P1 is the maximum distance between the first arc-shaped section 1111 and the first reference point K. In the embodiment, the reference circle on which the first arc-shaped section 1111 is located is the first reference circle P1. That is, the second arc-shaped section 1112 and the fifth arc-shaped section 1113 are deviated to the inner side of the first reference circle P1, so that the radial distance of the air gap 140 between the stator assembly and the rotor assembly 100 at the second arc-shaped section 1112 and the fifth arc-shaped section 1113 increases in the direction away from the first symmetry center line Z1, that is, the radial distance of the air gap 140 close to the first symmetry center line Z1 is larger, and the radial distance of the air gap 140 away from the first symmetry center line Z1 is smaller. In the circumferential direction of the rotor assembly 100, the radial distance of the air gap 140 is close to a sinusoidal distribution, so that the waveform of the air gap magnetic density distribution is close to a sinusoidal waveform, which is beneficial to reduce the harmonic components in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce vibration and noise.

[0061] At the same time, since the stator core 200 adopts a block structure, the structural stiffness of the stator core 200 is relatively poor compared with the stiffness of the overall annular structure. During the operation of the motor, the poor structural stiffness of the stator core 200 can cause vibration and noise. Therefore, by setting the first wall surface 111 as the second arc-shaped section 1112, the first arc-shaped section 1111 and the fifth arc-shaped section 1113 connected in sequence in the projection plane perpendicular to the rotation axis, and symmetrically arranging the second arc-shaped section 1112 and the fifth arc-shaped section 1113, the waveform of the air gap magnetic density distribution is close to a sinusoidal waveform, which is beneficial to reduce the harmonic components in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further improve the vibration and noise problems caused by the poor structural stiffness of the stator core 200, thereby reducing vibration and noise.

[0062] Of course, in other embodiments, the second arc-shaped section 1112 and the fifth arc-shaped section 1113 can be asymmetric, which can reduce the noise generated by resonance or excitation.

[0063] The embodiment of the second arc segment 1112 and the fifth arc segment 1113 arranged symmetrically is described in detail below, and the structure of the fifth arc segment 1113 can refer to the structure of the second arc segment 1112.

[0064] Referring to FIGS. 3 and 4, it can be understood that the central angle of the first arc segment 1111 is θ1, and the central angle of the second arc segment 1112 is θ2. When measuring θ1 and θ2, the protractor can be used to measure on the projection plane perpendicular to the rotation axis. The unit of the central angle θ1 of the first arc segment 1111 and the central angle θ2 of the second arc segment 1112 is °.

[0065] Referring to FIGS. 2 to 4, it can be understood that the minimum width W1 of the slot 231, the central angle θ1 of the first arc segment 1111, and the central angle θ2 of the second arc segment 1112 satisfy: 0.615≤W1*θ1 / θ2≤2. Wherein θ1 / θ2 can be understood as the relationship between the length and the radian of the first arc segment 1111 and the second arc segment 1112, which corresponds to the sine of the waveform of the air gap magnetic flux density distribution. Because the radial distance of the air gap 140 from the stator unit 220 to the slot 231 is suddenly changed, the air gap magnetic flux is suddenly changed, which causes the rotor assembly 100 to have a jerk feeling, the cogging torque pulsation is large, and a large vibration and noise are generated. Therefore, the value represented by W1*θ1 / θ2 is within a smaller range, i.e., not greater than 2, on the one hand, the minimum width of the slot 231 is not too large, which is beneficial to reduce the cogging torque pulsation; on the other hand, the value of θ1 / θ2 is not too large, i.e., it can be understood that the value of θ1 is small and the value of θ2 is large, so that the radial distance of the air gap 140 is closer to the sinusoidal distribution in the circumferential direction of the rotor assembly 100, thereby making the waveform of the air gap magnetic flux density distribution closer to the sinusoidal waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce the vibration and noise and reduce the distortion rate of the back EMF waveform.

[0066] It can be understood that, due to the too small slot 231, the magnetic lines of the magnetic field formed by part of the permanent magnet 120 are closed at the slot 231 without passing through the winding, causing magnetic leakage, and the magnetic field of the permanent magnet 120 cannot be fully utilized, resulting in low output torque and low output efficiency of the motor. And when the radial distance of the air gap 140 is too large, the air gap magnetic density is too weak, the magnetic field of the permanent magnet 120 cannot be fully utilized, and the output torque and output efficiency of the motor are also low. Therefore, the value represented by W1*θ1 / θ2 is minimized to 0.615, which can avoid the minimum width of the slot 231 being too small to cause magnetic leakage, and can avoid the maximum radial distance of the air gap 140 being too large to cause the air gap magnetic density at this position to be too weak, thereby ensuring that the magnetic field of the permanent magnet 120 is fully utilized, ensuring the output torque and output efficiency of the motor, and improving the performance of the motor. Therefore, 0.615≤W1*θ1 / θ2≤2, for example, the value represented by W1*θ1 / θ2 is 0.7, 1.0, 1.5 or 1.8, etc. On the premise of ensuring that the output torque and output efficiency of the motor meet the set requirements, reduce the magnetic leakage, and can reduce the cogging torque ripple, make the air gap magnetic density distribution waveform closer to the sine waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce vibration and noise, and reduce the distortion rate of the back EMF waveform.

[0067] Referring to FIG. 9, Base is the prior art scheme, the new scheme is the technical scheme of the present application, and the radial acceleration is used to represent the size of the vibration. The larger the radial acceleration, the greater the vibration, and vice versa. The figure shows the radial acceleration comparison of the prior art scheme and the present technical scheme at different frequencies. As can be seen from the figure, in addition to the radial acceleration of the present technical scheme being greater than that of the prior art scheme at 24 revolutions per minute, the radial acceleration of the present technical scheme is less than that of the prior art scheme at other frequencies, and the total radial acceleration of the present technical scheme is less than that of the prior art scheme. Therefore, the present technical scheme can significantly reduce vibration, thereby reducing noise.

[0068] Referring to FIGS. 5 and 7, it can be understood that, since the stator core 200 is of a split structure and is surrounded into a ring shape in a straight bar shape, it is easy to understand that, for the straight bar-shaped stator core 200, the minimum distance between the two adjacent shoe portions 222 is large, that is, the minimum width of the slot opening 231 is large at this time, on the one hand, the movement space of the winding nozzle is large, which is convenient for operation and can wind more wires, which is beneficial to improve the slot fill rate and improve the performance of the motor; on the other hand, since the minimum distance between the two adjacent shoe portions 222 is large at this time, the punching difficulty of the stator lamination is reduced, the dimensional accuracy is high, and the processing is convenient. After the winding operation is completed, the straight bar-shaped stator core 200 is surrounded into a ring shape, that is, a ring-shaped stator assembly is obtained, which is convenient for production, and at this time, since there is no need to consider the winding operation difficulty and processing difficulty, the slot opening 231 with a small width can be formed, which is beneficial to reduce the cogging torque ripple, reduce vibration and noise.

[0069] Referring to FIGS. 2 and 3, it can be understood that the minimum width W1 of the slot opening 231 and the central angle θ2 corresponding to the second arc-shaped section 1112 satisfy: 0.0405≤W1 / θ2≤0.1, that is, the minimum width of the slot opening 231 and the length and radian of the second arc-shaped section 1112 are further limited, so that the minimum width of the slot opening 231 and the length and radian of the second arc-shaped section 1112 are within a reasonable range, and the length and radian of the second arc-shaped section 1112 affect the sine degree of the waveform of the air gap flux density distribution. When the value represented by W1 / θ2 is too small, the minimum width of the slot opening 231 is too small, which causes magnetic leakage, and the maximum radial distance of the air gap 140 is too large, which causes the air gap flux density at this position to be too weak, and the output torque and output efficiency of the motor are low. When the value represented by W1 / θ2 is too large, the minimum width of the slot opening 231 is too large, which causes the cogging torque ripple to be too large, and the waveform of the air gap flux density distribution deviates from the sine waveform, the harmonic component in the air gap magnetic field is large, the vibration and noise are large, and the back EMF waveform distortion rate is large. Therefore, 0.0405≤W1 / θ2≤0.1, for example, the value represented by W1 / θ2 is 0.05, 0.07, 0.08 or 0.09, etc., under the premise that the output torque and output efficiency of the motor meet the set requirements, further reduce the magnetic leakage, and can reduce the cogging torque ripple, so that the waveform of the air gap flux density distribution is closer to the sine waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce the vibration and noise, and reduce the back EMF waveform distortion rate.

[0070] Referring to FIG. 3, it can be understood that the included angle between the two ends of the first arc segment 1111 and the line connecting the first reference point K (i.e., the central angle of the first arc segment 1111) θ1 and the central angle of the second arc segment 1112 θ2 satisfy: 0.41≤θ1 / θ2≤0.572. That is, the sine degree of the waveform of the air gap magnetic flux density distribution is further limited. When the value of θ1 / θ2 is too small, the maximum radial distance of the air gap 140 is too large, which causes the air gap magnetic flux at this position to be too weak, and the output torque and output efficiency of the motor are low; when the value of θ1 / θ2 is too large, the waveform of the air gap magnetic flux density distribution deviates from the sine waveform, the harmonic component in the air gap magnetic field is large, the vibration and noise are large, and the distortion rate of the back EMF waveform is large. Therefore, 0.41≤θ1 / θ2≤0.572, for example, the value represented by θ1 / θ2 is 0.5, 0.52, 0.55, or 0.56, etc., on the premise that the output torque and output efficiency of the motor meet the set requirements, further capable of reducing the cogging torque ripple, making the waveform of the air gap magnetic flux density distribution closer to the sine waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce the vibration and noise, and reduce the distortion rate of the back EMF waveform.

[0071] Referring to FIG. 6, it can be understood that along the circumferential direction of the stator core 200, the minimum width of the shoe portion 222 is defined as W2. Along the circumferential direction of the stator core 200, the shoe portion 222 has a seventh wall surface and an eighth wall surface facing away from each other, and the minimum distance between the seventh wall surface and the eighth wall surface is W2. When measuring W2, the vernier caliper can be used to measure the position where the distance between the seventh wall surface and the eighth wall surface is the smallest. In this embodiment, the minimum width of the shoe portion 222, i.e., the minimum distance W2 between the seventh wall surface and the eighth wall surface, is the minimum distance between the end of the seventh wall surface close to the rotation axis and the end of the eighth wall surface close to the rotation axis. It can also be understood that, in the projection plane perpendicular to the rotation axis, W2 is the distance between the projection of the end of the seventh wall surface close to the first reference point K and the projection of the end of the eighth wall surface close to the first reference point K. The unit of the minimum width W2 of the shoe portion 222 is mm.

[0072] Referring to FIGS. 2 and 6, it can be understood that the minimum width W1 of the slot 231 and the minimum width W2 of the shoe portion 222 satisfy: 0.088≤W1 / W2≤0.234. It can be easily understood that the minimum width W1 of the slot 231 and the minimum width W2 of the shoe portion 222 are inversely proportional, that is, the smaller the minimum width W2 of the shoe portion 222, the larger the minimum width W1 of the slot 231, and vice versa. When the value of W1 / W2 is too small, the minimum width of the slot 231 is too small, which can cause magnetic leakage, resulting in low output torque and low output efficiency of the motor. When the value of W1 / W2 is too large, on the one hand, the minimum width of the slot 231 is too large, the cogging torque pulsation is too large, and the vibration and noise are large; on the other hand, the minimum width of the shoe portion 222 is too small, the area of the shoe portion 222 for receiving the magnetic flux is too small, and the magnetic field of the permanent magnet 120 cannot be fully utilized, which also causes low output torque and low output efficiency of the motor. Therefore, 0.088≤W1 / W2≤0.234, for example, W1 / W2=0.1, W1 / W2=0.15, or W1 / W2=0.2, etc., under the premise of ensuring that the output torque and the output efficiency of the motor meet the set requirements, further reducing the magnetic leakage, and being able to reduce the cogging torque pulsation, thereby reducing the vibration and noise.

[0073] Referring to FIG. 6, it can be understood that along the radial direction of the stator core 200, the shoe portion 222 has a fourth wall surface 2221 on the side facing the rotation axis, that is, the fourth wall surface 2221 is the wall surface of the stator unit 220 facing the rotor core, that is, the fourth wall surface 2221 is the inner contour of the shoe portion 222, and the fourth wall surface 2221 is also part of the inner circumferential wall of the stator core 200. In the projection plane perpendicular to the rotation axis, the projection of the fourth wall surface 2221 includes a third arc segment 2222 and two fourth line segments 2223. The stator unit 220 has a second center of symmetry Z2 arranged along the radial direction of the stator core 200, and the second center of symmetry Z2 passes through the first reference point K. The third arc segment 2222 intersects the second center of symmetry Z2 and is symmetrically arranged about the second center of symmetry Z2. The two fourth line segments 2223 are respectively connected to the two ends of the third arc segment 2222 along the circumferential direction of the stator core 200, and the fourth line segment 2223 extends along the circumferential direction of the stator core 200 and in the direction away from the third arc segment 2222. The two fourth line segments 2223 are symmetrically arranged about the second center of symmetry Z2.

[0074] Referring to FIGS. 5 and 6, it can be understood that, in the embodiment, the third arc-shaped segment 2222 is a circular arc segment, and the center of the reference circle on which the third arc-shaped segment 2222 is located coincides with the first reference point K. The fourth line segment 2223 is a straight line segment, and the distance between the fourth line segment 2223 and the first reference point K increases in a direction away from the third arc-shaped segment 2222. A circle with a center at the first reference point K and a minimum inner diameter of the stator core 200 as a diameter is defined as a second reference circle P2. Generally, the minimum inner diameter of the stator core 200 is twice the minimum distance between the third arc-shaped segment 2222 and the first reference point K, that is, the radius of the second reference circle P2 is the minimum distance between the third arc-shaped segment 2222 and the first reference point K. In the embodiment, the reference circle on which the third arc-shaped segment 2222 is located is the second reference circle P2. That is, the fourth line segment 2223 deviates to the outside of the second reference circle P2. Generally, the third arc-shaped segment 2222 and the second arc-shaped segment 1112 are oppositely arranged in the radial direction of the stator core 200, so that the radial distance of the air gap 140 at the second arc-shaped segment 1112 increases in a direction away from the first center line of symmetry Z1, and the distance further increases, and then in the circumferential direction of the rotor assembly 100, the radial distance of the air gap 140 is closer to a sinusoidal distribution, so that the waveform of the air gap magnetic flux distribution is closer to a sinusoidal waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and then reduce vibration and noise, and reduce the distortion rate of the back electromotive force waveform.

[0075] Referring to FIG. 2, it can be understood that, since the center of the first reference circle P1, the center of the second reference circle P2, and the first reference point K coincide, generally, the first arc-shaped segment 1111 and the third arc-shaped segment 2222 are oppositely arranged in the radial direction of the rotor core, so that in the circumferential direction of the rotor assembly 100, the radial distance of the air gap 140 at the first arc-shaped segment 1111 is equal at different positions, that is, the air gap 140 at the first arc-shaped segment 1111 is a uniform air gap 140, and the radial distance of the air gap 140 at the first arc-shaped segment 1111 is the smallest. Therefore, in the circumferential direction of the rotor assembly 100, the range of the air gap 140 with the smallest radial distance is large, which is beneficial to the magnetic field generated by the permanent magnet 120 to pass through the air gap 140 more, to expand the range with large air gap magnetic flux, to fully utilize the magnetic field of the permanent magnet 120, and to improve the output efficiency and output torque of the motor, and to improve the performance of the motor.

[0076] Referring to FIG. 2, it can be understood that along the radial direction of the rotor core, the minimum distance of the air gap 140 is defined as L1, and the maximum distance of the air gap 140 is defined as L2. The units of L1 and L2 are mm. It can be easily understood that in the projection plane perpendicular to the rotation axis, the distance between the first arc segment 1111 and the third arc segment 2222 in the radial direction is the minimum distance L1 of the air gap 140, and the distance between the end of the second arc segment 1112 away from the first arc segment 1111 and the end of the fourth linear segment 2223 away from the third arc segment 2222 is the maximum distance L2 of the air gap 140. The minimum distance L1 of the air gap 140 and the maximum distance L2 of the air gap 140 satisfy: 0.107≤L1 / L2≤0.25. The ratio of L1 / L2 reflects the sine degree of the radial distance distribution of the air gap 140 in the circumferential direction of the rotor assembly 100, that is, the sine degree of the waveform of the air gap magnetic flux density distribution. When the value of L1 / L2 is too small, the minimum distance of the air gap 140 is too small, and the rotor core and the stator core 200 are easy to scratch during rotation of the rotor assembly 100, resulting in noise, and the maximum distance of the air gap 140 is too large, resulting in that the air gap magnetic flux at this position is too weak, and the output torque and output efficiency of the motor are relatively low. When the value of L1 / L2 is too large, the waveform of the air gap magnetic flux distribution deviates from the sine distribution, the harmonic component in the air gap magnetic field is large, the vibration and noise are large, and the distortion rate of the back EMF waveform is large. Therefore, 0.107≤L1 / L2≤0.25, for example, L1 / L2=0.15, L1 / L2=0.18, L1 / L2=0.2, or L1 / L2=0.23, etc., on the premise that the output torque and output efficiency of the motor meet the set requirements, avoid the rotor core and the stator core 200 from scratching, make the waveform of the air gap magnetic flux distribution closer to the sine waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce the vibration and noise, and reduce the distortion rate of the back EMF waveform.

[0077] Referring to FIGS. 2 and 3, it can be understood that the number of outer core units 110 is defined as N, and the maximum outer diameter of the rotor assembly 100 is D3, that is, the diameter of the first reference circle P1 is D3, which satisfies: 0.01≤L1*N / (π*D3)≤0.025. Generally, the number N of outer core units 110 is a determined value, and the maximum outer diameter of the rotor assembly 100 is a determined value, that is, the minimum distance of the air gap 140 is set according to the maximum outer diameter of the rotor assembly 100. Therefore, 0.01≤L1*N / (π*D3)≤0.025, for example, L1*N / (π*D3)=0.015, L1*N / (π*D3)=0.018, or L1*N / (π*D3)=0.02, etc., can avoid the drawbacks of noise caused by the rubbing between the rotor core and the stator core 200 due to the minimum distance of the air gap 140 being too small, and at the same time, can avoid the low output torque and output efficiency of the motor caused by the air gap magnetic flux at this position being too weak due to the minimum distance of the air gap 140 being too large. Therefore, under the premise of ensuring that the output torque and output efficiency of the motor meet the set requirements, the rubbing between the rotor core and the stator core 200 can be avoided to generate noise. At the same time, the minimum distance L1 of the air gap 140 satisfies: 0.3mm≤L1≤0.6mm, for example, L1=0.3mm, L1=0.4mm, or L1=0.5mm, etc., which will not be described here.

[0078] Referring to FIG. 4, it can be understood that the magnetic resistance of the core is smaller than that of the air, and in order to further optimize the magnetic field distribution of the permanent magnet 120, each outer core unit 110 is provided with a magnetic barrier hole 112, which penetrates the outer core unit 110 along the direction of the rotation axis. In the projection plane perpendicular to the rotation axis, the magnetic barrier hole 112 is located on one side of the first symmetry center line Z1, the projection of the magnetic barrier hole 112 is an elongated hole and has a center line arranged along the length direction, and the two ends of the magnetic barrier hole 112 along the direction of the center line respectively face the mounting groove 130 and the first wall surface 111, that is, the included angle between the center line of the magnetic barrier hole 112 and the first symmetry center line Z1 is an acute angle. Therefore, when the magnetic field generated by the permanent magnet 120 is guided to the air gap 140 through the outer core unit 110, the magnetic field of the permanent magnet 120 does not pass through the magnetic barrier hole 112, and it can also be understood that the magnetic barrier hole 112 divides the magnetic field on the outer core unit 110, so that the magnetic field is concentrated to the position of the first symmetry center line Z1, thereby optimizing the magnetic field distribution on the outer core unit 110, making the waveform of the air gap magnetic flux distribution closer to a sine waveform, which is beneficial to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and further reduce vibration and noise, and reduce the distortion rate of the back electromotive force waveform, thereby improving the back electromotive force waveform.

[0079] Referring to FIG. 4 and FIG. 8, it can be understood that in the embodiment, each outer iron core unit 110 is provided with two magnetic barrier holes 112, the two magnetic barrier holes 112 are symmetrically arranged about the first center line of symmetry Z1, and the distance of the two magnetic barrier holes 112 in the direction perpendicular to the first center line of symmetry Z1 decreases from the rotation axis to the outside of the rotor core. The included angle of the center lines of the two magnetic barrier holes 112 is defined as θ3, and the unit of θ3 is °. The minimum width W1 of the slot opening 231 and the included angle θ3 of the center lines of the two magnetic barrier holes 112 satisfy: 0.033≤W1 / θ3≤0.14. That is, the value of the included angle of the center lines of the two magnetic barrier holes 112 is set according to the minimum width of the slot opening 231. Under the premise that the value of the minimum width W1 of the slot opening 231 is determined, 0.033≤W1 / θ3≤0.14, for example, the value represented by W1 / θ3 is 0.04, 0.06, 0.08, 0.1 or 0.12, etc., which can make the included angle of the center lines of the two magnetic barrier holes 112 and the magnetic field direction on the outer iron core unit 110 not too large, thereby optimizing the magnetic field distribution on the outer iron core unit 110, so that the waveform of the air gap magnetic flux density distribution is closer to the sine waveform.

[0080] Referring to FIG. 2 to FIG. 4, it can be understood that the minimum width W1 of the slot opening 231, the included angle (that is, the central angle corresponding to the first arc segment 1111) θ1 between the two ends of the first arc segment 1111 and the first reference point K, and the included angle θ3 of the center lines of the two magnetic barrier holes 112 satisfy: 0.49≤W1*θ1 / θ3≤5.58. That is, the included angle of the center lines of the two magnetic barrier holes 112 is further limited, and the value of the included angle of the center lines of the two magnetic barrier holes 112 is more accurately set according to the minimum width of the slot opening 231 and the central angle θ1 corresponding to the first arc segment 1111. Under the premise that the value of the minimum width W1 of the slot opening 231 and the central angle θ1 corresponding to the first arc segment 1111 are determined, 0.49≤W1*θ1 / θ3≤5.58, for example, the value represented by W1*θ1 / θ3 is 0.5, 0.9, 1.5, 2 or 3, etc., to further optimize the value range of the included angle of the center lines of the two magnetic barrier holes 112, so that the direction of the center lines of the two magnetic barrier holes 112 is closer to the magnetic field direction on the outer iron core unit 110, thereby further optimizing the magnetic field distribution on the outer iron core unit 110, so that the waveform of the air gap magnetic flux density distribution is closer to the sine waveform.

[0081] It can be understood that in order to improve the output torque of the motor, the magnetic field of the permanent magnet 120 is generally increased, and therefore the thickness of the permanent magnet 120 needs to be increased, that is, the width of the mounting groove 130 in the circumferential direction of the rotor core needs to be increased. If the width of the mounting groove 130 in the circumferential direction of the rotor core is too large, the end of the two adjacent mounting grooves 130 close to the rotation axis will interfere, and the permanent magnet 120 cannot be installed.

[0082] To this end, referring to FIG. 4, it can be understood that, along the circumferential direction of the rotor core, the mounting slot 130 has oppositely arranged second wall surface 131 and third wall surface 132, which are respectively recessed towards opposite directions, that is, the second wall surface 131 and the third wall surface 132 are respectively recessed towards two sides of the mounting slot 130 along the circumferential direction of the rotor core, and the projections of the second wall surface 131 and the third wall surface 132 on the projection plane perpendicular to the rotation axis can be arc segments, broken line segments or curve segments, that is, in the radial direction of the rotor core, the mounting slot 130 is wide in the middle and narrow at both ends. Correspondingly, the outer contour of the permanent magnet 120 matches the inner contour of the mounting slot 130 on the projection plane perpendicular to the rotation axis. That is, from the middle of the permanent magnet 120 to the two ends of the permanent magnet 120 in the radial direction, the distance between the two wall surfaces of the permanent magnet 120 along the circumferential direction decreases, and the permanent magnet 120 is wide in the middle and narrow at both ends. Therefore, the maximum width of the mounting slot 130 in the circumferential direction of the rotor core can be increased, that is, the maximum width of the permanent magnet 120 can be increased, the magnetic field generated by the permanent magnet 120 is enhanced, the torque density is improved, and the output torque of the motor is improved. At the same time, the width of the mounting slot 130 near one end of the rotation axis is not too large, interference is avoided, the structure is reasonable, and the structural strength of the rotor core is ensured.

[0083] In other embodiments, alternatively, the distance between the second wall surface 131 and the third wall surface 132 in the circumferential direction of the rotor core decreases from the direction of the stator assembly towards the rotation axis, that is, from the outside to the inside, and the second wall surface 131 and the third wall surface 132 are both planes, that is, in the radial direction of the rotor core, the mounting slot 130 is wide on the outside and narrow on the inside, that is, on the projection plane perpendicular to the rotation axis, the projection of the mounting slot 130 is a trapezoidal shape. Therefore, the maximum width of the permanent magnet 120 can also be increased, the magnetic field generated by the permanent magnet 120 is enhanced, and the width of the mounting slot 130 near one end of the rotation axis is not too large, interference is avoided.

[0084] As shown in FIG. 5, it can be understood that the maximum outer diameter of the stator assembly is defined as D1, and the minimum inner diameter of the stator assembly is defined as D2. It can be easily understood that the maximum outer diameter of the stator assembly is the maximum outer diameter of the stator core 200, and the minimum inner diameter of the stator assembly is the minimum inner diameter of the stator core 200. In this embodiment, the maximum outer diameter of the stator core 200 is the diameter of the circumscribed circle of the projection of the outer circumferential wall of the stator core 200 which is a regular polygon in the projection plane perpendicular to the rotation axis, and the minimum inner diameter of the stator core 200 is the inner diameter of the second reference circle P2. The unit of the maximum outer diameter D1 of the stator assembly and the minimum inner diameter D2 of the stator assembly is mm, and satisfies: 0.58≤D2 / D1≤0.625. Generally, in order to meet the installation requirements of the motor, the outer diameter of the stator core 200 is a certain value. On the premise that the maximum radial distance of the air gap 140 remains unchanged, the value of D2 / D1 is not less than 0.58, which can increase the minimum inner diameter of the stator core 200, and thus the maximum outer diameter of the rotor core can be increased, so that a larger space installation slot 130 can be provided on the rotor core to install thicker permanent magnets 120, thereby increasing the magnetic field generated by the permanent magnets 120, improving the torque density, and helping to improve the output torque of the motor. At the same time, the value of D2 / D1 is not more than 0.625, which can avoid the problem that the minimum inner diameter of the stator core 200 is too large, thereby avoiding the radial width of the yoke portion 240 being too small, and thus avoiding the problems of the structural strength of the stator core 200 being reduced and the magnetic flux saturation phenomenon being prone to occur at the yoke portion 240, thereby improving the reliability of the motor operation. At the same time, it can avoid the problem that the space of the winding slot 230 is too small to affect the size of the winding, thereby helping to ensure that the performance of the motor meets the set requirements.

[0085] The household appliance of the second aspect embodiment of the present application comprises the motor of the first aspect embodiment of the present application. The household appliance can be a washing machine, a clothes dryer, etc. In the washing machine or the clothes dryer, the motor drives the rotation of the drum of the washing machine or the clothes dryer.

[0086] The household appliance adopts all the technical solutions of the motor of the above embodiments, and thus at least has all the beneficial effects brought by the technical solutions of the above embodiments, including but not limited to: the household appliance adopts the motor, the projection of the outer contour of the outer core unit of the rotor assembly is set to comprise the second arc segment, the first arc segment and the fifth arc segment connected in sequence, and the distance between the second arc segment and the rotation axis decreases in the direction away from the first arc segment, and the distance between the fifth arc segment and the rotation axis decreases, so that the radial distance of the air gap between the rotor assembly and the stator assembly is close to a sinusoidal distribution in the circumferential direction of the rotor assembly, thereby the waveform of the air gap magnetic flux density distribution is close to a sinusoidal waveform, which is helpful to reduce the harmonic component in the air gap magnetic field, reduce the effect of the harmonic magnetic field, and thus reduce vibration and noise, reduce the waveform distortion rate of the back electromotive force, and improve the performance of the motor.

[0087] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. An electric machine, comprising: a rotor assembly rotating around an axis of rotation, the rotor assembly comprising a plurality of outer core units and a plurality of permanent magnets, the plurality of outer core units being arranged along a circumferential direction of the rotor assembly, two adjacent outer core units defining a mounting slot therebetween, the plurality of permanent magnets being mounted in the plurality of mounting slots, in a projection plane perpendicular to the axis of rotation, a projection of an outer contour of the core unit comprises a second arc segment, a first arc segment and a fifth arc segment connected in sequence, in a direction away from the first arc segment, the second arc segment is away from the axis of rotation, the fifth arc segment is away from the axis of rotation; and a stator assembly comprising a stator core arranged around an outer periphery of the rotor assembly, the stator core comprising a plurality of stator units arranged along the circumferential direction, the stator unit comprising a yoke portion, a tooth portion and a shoe portion, the yoke portion and the shoe portion being connected to two radial ends of the tooth portion respectively, a radial outer wall surface and a radial inner wall surface of the yoke portion are parallel planes, two adjacent yoke portions are connected, two adjacent stator units define a wire slot therebetween, two adjacent shoe portions define a slot opening of the wire slot. The second arc segment and the fifth arc segment are symmetrically arranged. In the circumferential direction, the minimum width of the slot opening is W1, the central angle corresponding to the first arc segment is θ1, the central angle corresponding to the second arc segment is θ2, and 0.615≤W1*θ1 / θ2≤2 is satisfied. The minimum width W1 of the slot opening and the central angle θ2 corresponding to the second arc segment satisfy 0.0405≤W1 / θ2≤0.

1.

2. The electric machine of claim 1, wherein, The central angle θ1 corresponding to the first arc segment and the central angle θ2 corresponding to the second arc segment satisfy 0.41≤θ1 / θ2≤0.

572.

3. The electric machine of claim 2, wherein, In the circumferential direction, the shoe portion is convexly arranged towards both sides of the tooth portion, the minimum width of the shoe portion along the circumferential direction is W2, and 0.088≤W1 / W2≤0.234 is satisfied.

4. The electric machine of claim 3, wherein, In the projection plane perpendicular to the axis of rotation, a projection of an inner contour of the shoe portion comprises a third arc segment and a fourth linear segment connected to both ends of the third arc segment respectively, in a direction away from the third arc segment, the fourth linear segment is away from the axis of rotation.

5. The electric machine of claim 3 or 4, wherein, The outer periphery wall of the rotor assembly and the inner periphery wall of the stator assembly have an air gap therebetween, in a direction perpendicular to the axis of rotation, the minimum distance of the air gap is L1, the maximum distance of the air gap is L2, and 0.107≤L1 / L2≤0.25 is satisfied.

6. The electric machine of any one of claims 3 to 5, wherein, The number of outer core units is N, and the maximum outer diameter of the rotor assembly is D3, and 0.01≤L1*N / (π*D3)≤0.025 is satisfied.

7. The electric machine of claim 6, wherein, The minimum distance L1 of the air gap satisfies 0.3mm≤L1≤0.6mm.

8. The electric machine of any one of claims 1 to 7, wherein, The outer core unit is provided with a magnetic barrier hole, in the projection plane perpendicular to the axis of rotation, a projection of the magnetic barrier hole is strip-shaped and has a length direction, and both ends of the magnetic barrier hole along the length direction are respectively towards the mounting slot and the outer contour of the outer core unit.

9. The electric machine of claim 8, wherein, ​ 10. The electric machine of claim 8 or 9, wherein, ​ 11. The electric machine of any one of claims 1 to 10, wherein, ​ 12. The electric machine of claim 11, wherein, The number of the magnetic barrier holes of each outer iron core unit is two, two magnetic barrier holes are symmetrically arranged about the first symmetry center line of the outer iron core unit, and the included angle of two magnetic barrier holes is θ3, and 0.033≤W1 / θ3≤0.14 is satisfied.

13. The electric machine of claim 12, wherein, The minimum width W1 of the slot, the central angle θ1 corresponding to the first arc-shaped segment, and the included angle θ3 of two magnetic barrier holes satisfy 0.49≤W1*θ1 / θ3≤5.

58.

14. The electric machine of any one of claims 1 to 13, wherein, From the middle of the permanent magnet to the two ends of the permanent magnet along the radial direction, the distance between the two wall surfaces of the permanent magnet away from each other along the circumferential direction decreases.

15. The electric machine of any one of claims 1 to 14, wherein, The maximum outer diameter of the stator assembly is D1, and the minimum inner diameter of the stator assembly is D2, and 0.58≤D2 / D1≤0.625 is satisfied.

16. The electric machine of any one of claims 1 to 15, wherein, The outer iron core unit comprises a second limiting protrusion, the second limiting protrusion is located at one end of the mounting groove away from the rotation axis, and the second limiting protrusion comprises a fixed part, the fixed part is located at one end of the second limiting protrusion away from the mounting groove and is arranged protruding along the circumferential direction.

17. The electric machine of any one of claims 1 to 16, wherein, The rotor assembly further comprises a first plastic covering part, the first plastic covering part covers the outer iron core unit and the permanent magnet, and the stator assembly further comprises a second plastic covering part, the second plastic covering part covers the stator core.

18. A household appliance comprising an electric machine according to any one of claims 1 to 17.

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