Rotor assembly, motor and household appliance

Abstract

The invention discloses a rotor assembly, a motor and a household electrical appliance, the rotor assembly comprises a rotor core and a plurality of permanent magnets, the rotor core comprises a plurality of iron core units arranged at intervals along the circumferential direction of the rotor core, and each iron core unit is composed of a plurality of punching sheet monomers stacked along the direction of a rotation axis. An installation groove is defined between every two adjacent iron core units, a groove is formed in the side, away from the rotating axis, of each iron core unit, and the multiple permanent magnets are correspondingly installed in the multiple installation grooves. The grooves are formed, the material consumption of the rotor iron core can be reduced, the material cost is saved, the magnetic field on the side, away from the rotating axis, of the iron core unit is weak when the grooves are not formed, and therefore the motor performance can be kept while the materials are reduced; when the punching sheet single bodies are subjected to stock layout, the positions of the parts, corresponding to the grooves, on the punching sheet single bodies can be fully utilized, so that the stock layout is tighter, waste materials are reduced, the utilization rate of silicon steel plates is improved, and the production cost of the rotor assembly is reduced.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a rotor assembly, a motor, and a household appliance. Background Technology

[0002] Brushless DC motors are widely used in various household appliances due to their simple structure and reliable operation. Currently, the household appliance market is highly competitive, making the pursuit of low cost particularly important. As one of the core components of household appliances, the production cost of the appliance is closely related to the production cost of the motor. Among related technologies, current external rotor motors have relatively high overall production costs, especially material costs. Furthermore, the utilization rate of silicon steel plates during production is low, resulting in a still relatively high production cost even without affecting motor performance. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a rotor assembly that has low production cost, high silicon steel plate utilization rate, and can guarantee motor performance.

[0004] The present invention also provides an electric motor having the above-described rotor assembly.

[0005] The present invention also provides a household appliance having the above-mentioned motor.

[0006] According to a first aspect of the present invention, a rotor assembly rotatable about a rotation axis includes: a rotor core comprising a plurality of core units arranged circumferentially spaced along the rotor core, each core unit being composed of a plurality of laminations stacked together along the rotation axis, a mounting groove defining a space between adjacent core units, and a groove provided on the side of each core unit facing away from the rotation axis; and a plurality of permanent magnets correspondingly mounted in the plurality of mounting grooves.

[0007] The rotor assembly according to the first aspect of the present invention has at least the following beneficial effects: by providing a groove on the side of the core unit away from the rotation axis, the amount of silicon steel sheet material used can be reduced, which is beneficial to reducing material costs; since the magnetic field on the side of the core unit away from the rotation axis is weak when the groove is not provided, the impact on the overall magnetic field strength of the core unit is small after the groove is provided, so the performance of the motor can be guaranteed while reducing material; at the same time, after the groove is provided, the position of the part corresponding to the groove on the lamination unit can be fully utilized when arranging the lamination units, making the arrangement more compact, reducing waste, improving the utilization rate of silicon steel sheet, reducing processing costs, and thus reducing the overall production cost of the rotor assembly.

[0008] According to an embodiment of the first aspect of the present invention, the groove extends through both ends of the rotor core along the direction of the rotation axis.

[0009] According to an embodiment of a first aspect of the present invention, the core unit has a centerline arranged radially along the rotor core, and the sidewall of the groove includes a first wall surface and a second wall surface arranged circumferentially opposite each other, the first wall surface and the second wall surface being symmetrically arranged with respect to the centerline.

[0010] According to an embodiment of the first aspect of the present invention, both the first wall surface and the second wall surface extend to the centerline, and the angle between the first wall surface and the second wall surface is not less than 90°.

[0011] According to an embodiment of the first aspect of the present invention, the angle between the first wall surface and the second wall surface is an acute angle, and the end of the first wall surface near the axis of rotation and the end of the second wall surface near the axis of rotation are connected by an arc transition.

[0012] According to an embodiment of the first aspect of the present invention, the maximum depth of the groove along the radial direction of the rotor core is H, and the maximum width of the core unit is W, satisfying: 1 / 3 ≤ H / W ≤ 2 / 3.

[0013] According to an embodiment of the first aspect of the present invention, the core unit includes a first limiting portion and a second limiting portion located on the same side along the circumferential direction, both the first limiting portion and the second limiting portion protruding toward the mounting groove, and the first limiting portion and the second limiting portion respectively abutting against both ends of the permanent magnet along the radial direction of the rotor core.

[0014] According to an embodiment of the first aspect of the present invention, there are two of each of the first limiting portion and the second limiting portion, with the two first limiting portions located on both sides of the core unit along the circumferential direction, and the two second limiting portions located on both sides of the core unit along the circumferential direction.

[0015] According to an embodiment of the first aspect of the present invention, the core unit is provided with positioning holes, which penetrate both ends of the core unit along the direction of the rotation axis.

[0016] According to an embodiment of the first aspect of the present invention, the core unit is provided with injection holes, which penetrate both ends of the core unit along the direction of the rotation axis.

[0017] According to an embodiment of the first aspect of the present invention, the rotor assembly further includes a plastic-coated body, a portion of which fills the injection hole.

[0018] According to a second aspect of the present invention, the motor includes a rotor assembly according to a first aspect of the present invention, and the motor further includes a stator assembly, the rotor assembly being wound around the outer periphery of the stator assembly.

[0019] The motor according to a second aspect embodiment of the present invention has at least the following beneficial effects: Compared with the prior art, the rotor assembly in the motor is provided with an iron core unit, and a groove is provided on the side of the iron core unit away from the rotation axis, which can reduce the amount of silicon steel plate material used and help reduce material costs; since the magnetic field on the side of the iron core unit away from the rotation axis is weak when the groove is not provided, the influence of the overall magnetic field strength of the iron core unit is small after the groove is provided, so the performance of the motor can be guaranteed while reducing material; at the same time, after the groove is provided, the position of the part on the lamination unit corresponding to the groove can be fully utilized when the lamination unit is arranged, so that the arrangement is more compact, waste is reduced, and the utilization rate of silicon steel plate is improved, thereby reducing the manufacturing cost of the motor while maintaining the performance of the motor.

[0020] A household appliance according to a third aspect of the present invention includes a motor according to a second aspect of the present invention.

[0021] According to a third aspect of the present invention, the household appliance has at least the following beneficial effects: Compared with the prior art, the household appliance includes a motor, and the rotor assembly of the motor includes an iron core unit. A groove is provided on the side of the iron core unit away from the rotation axis, which can reduce the amount of silicon steel sheets used, thereby saving material costs. At the same time, the magnetic field on the side of the iron core unit away from the rotation axis is weak when the groove is not provided. After the groove is provided, the impact on the overall magnetic field strength of the iron core unit is small. Therefore, the performance of the motor can be guaranteed while reducing materials. In addition, after the groove is provided, when the laminations are arranged, the positions of the parts corresponding to the grooves on the laminations can be fully utilized, making the arrangement more compact, reducing waste, and improving the utilization rate of silicon steel sheets. Thus, the manufacturing cost of the household appliance is reduced while maintaining performance.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 This is an axial schematic diagram of the rotor assembly with one of the permanent magnets removed in an embodiment of the first aspect of the present invention;

[0025] Figure 2 yes Figure 1 Enlarged view of point A in the image;

[0026] Figure 3 This is an axial schematic diagram of the motor in an embodiment of the second aspect of the present invention;

[0027] Figure 4This is an axial schematic diagram of the core unit in some embodiments of the first aspect of the present invention;

[0028] Figure 5 This is an axial schematic diagram of the core unit in some other embodiments of the first aspect of the present invention;

[0029] Figure 6 This is a schematic diagram of the arrangement of the stamping monomers in the material plate in some embodiments of the first aspect of the present invention;

[0030] Figure 7 This is a partial view of the arrangement of the sheet monomers in the blank in some other embodiments of the first aspect of the present invention.

[0031] Figure label:

[0032] Rotor core 100; permanent magnet 101;

[0033] Material plate 110; stamping unit 111; recess 112; branch 113;

[0034] Iron core unit 120; mounting groove 121; recess 122; center line 123; first wall surface 124; second wall surface 125; positioning hole 126; injection hole 127; first limiting part 128; second limiting part 129; third wall surface 130; fourth wall surface 131;

[0035] Stator assembly 140; stator teeth 141; winding 142; winding slot 143. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0038] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0039] In the description of this invention, unless otherwise explicitly defined, terms such as setting, installing, connecting, assembling, and cooperating should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0040] Brushless DC motors are widely used in fans, pumps, robots, drones, electric vehicles, precision instruments, and home appliances due to their high efficiency, long lifespan, low noise, and high-precision control. Currently, the home appliance market is highly competitive, making the pursuit of low costs particularly important. As one of the core components of home appliances, the production cost of the motor is closely related to the production cost of the appliance itself. Among related technologies, the overall production cost of external rotor motors is currently high, especially in terms of material costs. Furthermore, the material utilization rate during production is low. Even without affecting motor performance, the production cost remains high, meaning it is difficult to reduce motor costs without compressing the rotor size. Currently, the rotor core in external rotor motors is composed of multiple laminations stacked together. These laminations are obtained by stamping silicon steel sheets. While it's understandable that multiple laminations are arranged on the sheet, the current lamination arrangement is not ideal, resulting in low material utilization and significant material waste during production, making it difficult to reduce production costs.

[0041] To solve the above technical problems, refer to Figure 1 As shown, an embodiment of the first aspect of the present invention provides a rotor assembly for use in the motor of a household appliance, including refrigerators, air conditioners, washing machines, etc. It is understood that, referring to... Figure 3 The motor includes a rotor assembly and a stator assembly 140. The stator assembly 140 includes a plurality of stator teeth 141. There is a winding slot 143 between two adjacent stator teeth 141, and a winding 142 is provided at the winding slot 143.

[0042] It can be understood that the rotor core 100 has a central axis, which is the rotation axis of the rotor assembly. The rotor assembly surrounds the outer periphery of the stator assembly 140 and rotates around the rotation axis. It should be noted that, for ease of description and understanding, the direction surrounding the rotation axis of the rotor assembly is referred to as the circumferential direction C in this application.

[0043] Reference Figure 1 and Figure 3 The rotor assembly includes a rotor core 100 and a plurality of permanent magnets 101. The rotor core 100 includes a plurality of core units 120 arranged at equal intervals along the circumferential direction C. A mounting slot 121 is defined between two adjacent core units 120, and the plurality of permanent magnets 101 are correspondingly installed in the plurality of mounting slots 121. It can be understood that the plurality of permanent magnets 101 and the plurality of core units 120 are arranged alternately along the circumferential direction C, that is, a permanent magnet 101 is provided between two adjacent core units 120.

[0044] Reference Figure 2 The core unit 120 has a centerline 123 arranged radially along the rotor core 100. The core unit 120 includes a first limiting portion 128 and a second limiting portion 129 located on the same side along the circumferential direction C. Both the first limiting portion 128 and the second limiting portion 129 protrude toward the mounting groove 121. Specifically, the first limiting portion 128 is located on the side of the core unit 120 away from the rotation axis, and the second limiting portion 129 is located on the side of the core unit 120 close to the rotation axis. Along the radial direction of the rotor core 100, the first limiting portion 128 abuts against the end of the permanent magnet 101 away from the rotation axis, and the second limiting portion 129 abuts against the end of the permanent magnet 101 close to the rotation axis, thereby limiting the permanent magnet 101 and firmly installing the permanent magnet 101 in the rotor core 100, preventing the permanent magnet 101 from detaching from the rotor core 100 when the rotor assembly rotates.

[0045] Reference Figure 2 It is understandable that the core unit 120 has two first limiting parts 128 and two limiting parts 129. The two first limiting parts 128 are located on both sides of the core unit 120 along the circumferential direction C, and the two second limiting parts 129 are located on both sides of the core unit 120 along the circumferential direction C. This increases the contact between the core unit 120 and the permanent magnet 101 along the radial direction of the rotor core 100, thereby making the connection more solid, which is beneficial to improving the structural stability of the rotor core 100, avoiding vibration during the operation of the motor, and ensuring the performance of the motor.

[0046] Reference Figure 1 The iron core unit 120 has a groove 122 on the side opposite to the rotation axis, which can reduce the amount of material used in the iron core unit 120, thereby saving material costs.

[0047] It is understandable that during the operation of the external rotor motor, the magnetic field direction originates from the permanent magnet 101 (refer to...). Figure 3The magnetic field lines (N) pass sequentially through the core unit 120 located on one side of the permanent magnet 101, the air gap between the stator assembly 140 and the rotor assembly, the stator teeth 141, and the winding 142. After passing through the winding 142, the magnetic field passes through the stator teeth 141 located on the other side of the winding 142, and then passes through the air gap and the core unit 120 located on the other side of the permanent magnet 101 again, before returning to the permanent magnet 101. It can be seen that the magnetic field is conducted to the side of the rotor assembly close to the rotation axis. The magnetic field line density is lower and the magnetic field is weaker on the side of the core unit 120 away from the rotation axis. After setting the groove 122 here, the impact on the overall magnetic field strength of the core unit 120 is small. Therefore, it is possible to save the material usage of the rotor core 100 while maintaining the motor performance, which is beneficial to reducing material costs.

[0048] It is understandable that the core unit 120 consists of multiple lamination units 111 stacked along the rotation axis, and the lamination units 111 are formed by stamping silicon steel sheets. (Refer to...) Figure 6 The material plate 110 is a silicon steel plate, and the stamped individual pieces 111 are arranged on the material plate 110.

[0049] Reference Figure 6 It is understood that the lamination unit 111 is provided with a recess 112, and multiple recesses 112 arranged along the rotation axis form a groove 122. It is understood that the groove 122 penetrates both ends of the rotor core 100 along the rotation axis, which can effectively reduce the material usage of the core unit 120 and significantly reduce costs. Furthermore, each lamination unit 111 that makes up the core unit 120 is provided with a recess 112, so that there is only one type of lamination unit 111, which can reduce the number of dies and thus reduce processing costs.

[0050] In another embodiment, the groove 122 may not penetrate through both ends of the rotor core 100. The core unit 120 includes a plurality of laminations 111 without the groove 112. The plurality of laminations 111 without the groove 112 may be stacked in a concentrated manner at any position of the core unit 120, or may be staggered with the laminations 111 with the groove 112, which can also achieve the effect of reducing material usage.

[0051] Reference Figure 6It is understood that the stamping unit 111 includes branch portions 113 located on both sides of the recess 112. When the stamping unit 111 is arranged in the material plate 110, any branch portion 113 on the stamping unit 111 can be inserted into the recess 112 of the adjacent stamping unit 111 along the width direction of the material plate 110. Furthermore, along the length direction of the material plate 110, a recess 112 can accommodate two branch portions 113 located on different stamping units 111. Therefore, by providing a recess 112 on the stamping unit 111, the area of ​​the material plate 110 occupied by two adjacent stamping units 111 along the width direction of the material plate 110 can be reduced, thereby allowing more stamping units 111 to be arranged on the material plate 110 of the same area, thus improving the utilization rate of the material plate 110.

[0052] Understandably, currently, by punching the material plate 110 with a die, multiple blanking units 111 can be punched out in one punching operation on the material plate 110 of a certain area. When a recess 112 is provided on the blanking unit 111, more blanking units 111 can be arranged on the material plate 110 of the same area. Thus, the die can produce a larger number of blanking units 111 after punching the material plate 110 in one operation, which is beneficial to improving processing efficiency and reducing production costs.

[0053] Reference Figure 2 The sidewalls of the groove 122 include a first wall surface 124 and a second wall surface 125 arranged opposite each other along the circumferential direction C. The first wall surface 124 and the second wall surface 125 are symmetrically arranged with respect to the center line 123, and the first wall surface 124 and the second wall surface 125 are planar. It can be understood that permanent magnets 101 of the same specification are symmetrically arranged on both sides of the core unit 120. Therefore, in actual operation, the magnetic field passing through the core unit 120 is symmetrical with respect to the center line 123. Therefore, the symmetrical first wall surface 124 and second wall surface 125 are arranged on the groove 122 so that the hollowing out of the area on both sides of the center line 123 on the core unit 120 is the same, and the influence on the magnetic field on both sides of the center line 123 is the same, thereby making the magnetic field uniformly distributed and avoiding vibration caused by uneven magnetic field during motor operation.

[0054] Meanwhile, since the outer contour of the groove 122 is symmetrical, the symmetrical structure of the groove 112 for the lamination unit 111 means that it is not necessary to distinguish the installation direction of each lamination unit 111 during the installation of the rotor core 100, thereby simplifying the installation steps, reducing the defect rate caused by installation errors, and thus ensuring production efficiency.

[0055] Reference Figure 4It is understood that the inner ends of the first wall 124 and the second wall 125 near the axis of rotation both extend to the center line 123. That is, the intersection of the first wall 124 and the second wall 125 is located on the center line 123, and the included angle between the first wall 124 and the second wall 125 is not less than 90°, that is, they are perpendicular to each other or the included angle is an obtuse angle. This can prevent the material plate 110 from sticking to the mold during the punching process, thereby avoiding defective products and ensuring the efficiency of material feeding and waste removal.

[0056] It is understandable that if the angle between the first wall 124 and the second wall 125 is less than 90°, the punched piece 111 is prone to sticking to the mold during the punching process, which will lead to difficulties in layout or defects in the cut surface, resulting in a high defect rate and reduced production efficiency.

[0057] Therefore, referring to Figure 4 The angle between the first wall surface 124 and the second wall surface 125 is defined as α. When the angle α is acute, the end of the first wall surface 124 near the rotation axis and the end of the second wall surface 125 near the rotation axis are connected by an arc surface transition. An arc surface S is defined between the first wall surface 124 and the second wall surface 125 to connect them, which can prevent the mold or punch from sticking to the stamping unit 111, thereby avoiding processing defects and improving yield and processing efficiency.

[0058] Reference Figure 7 Since the branch portion 113 on the stamping unit 111 has a circumferentially protruding portion C that constitutes the first limiting portion 128, after the arc surface S is provided between the first wall surface 124 and the second wall surface 125, the gap between the first limiting portion 128 on the branch portion 113 and the arc surface S located on the recess 112 can be reduced during the layout process, thereby reducing the amount of waste and helping to improve the utilization rate of the material plate 110.

[0059] Reference Figure 4 Along the radial direction of the rotor core 100, the maximum depth of the groove 122 is H, and the maximum width of the core unit 120 is W, satisfying: 1 / 3≤H / W≤2 / 3.

[0060] It is understandable that the two first limiting parts 128 are symmetrical about the center line 123 and along the radial direction of the rotor core 100. A third wall surface 130 is provided on the side of the first limiting part 128 away from the rotation axis. At the same time, a fourth wall surface 131 is provided on the side wall of the core unit 120 near the rotation axis. In actual measurement, the maximum width W of the core unit 120 is the maximum distance between the third wall surface 130 and the fourth wall surface 131 along the radial direction of the rotor core 100.

[0061] It should be noted that the farthest end of the core unit 120 from the axis of rotation has a maximum circumcircle Q1, and the closest end of the core unit 120 from the axis of rotation has a minimum incircle Q2.

[0062] It is understandable that when the third wall 130 is located on the circumcircle Q1, the radius of the largest circumcircle Q1 is the maximum distance between the third wall 130 and the rotation axis, and the center of the largest circumcircle Q1 is located on the rotation axis; when the fourth wall 131 is located on the incircle Q2, the radius of the smallest incircle Q2 is the minimum distance between the fourth wall 131 and the rotation axis, and the center of the smallest incircle Q2 is located on the rotation axis. Therefore, along the radial direction of the rotor core 100, the maximum width W of the core unit 120 is the difference between the radii of the largest circumcircle Q1 and the smallest incircle Q2.

[0063] Understandably, when H / W < 1 / 3, the radial depth of the groove 122 along the rotor core 100 is small, resulting in a smaller amount of material removed from the core unit 120 and a smaller impact on the magnetic field. However, this leads to insufficient material savings and insignificant cost reduction, failing to meet the requirement of significantly reducing material costs while maintaining motor performance. Regarding layout, when H / W < 1 / 3, the area of ​​each lamination unit 111 increases, reducing the number of lamination units 111 arranged on a given area of ​​material plate 110. This reduces the utilization rate of the material plate 110 and decreases the number of lamination units 111 produced per punching cycle, resulting in low processing efficiency and failing to meet requirements.

[0064] When H / W > 2 / 3, the radial depth of the groove 122 along the rotor core 100 is large, resulting in a significant material removal from the core unit 120. This can easily lead to a decrease in the strength of the core unit 120, causing insufficient structural strength of the rotor core 100. Consequently, vibration is easily generated during rotation, reducing motor performance. Furthermore, when the radial depth of the groove 122 along the rotor core 100 is excessive, the material removal from the core unit 120 along the circumferential direction C is also excessive. This can easily lead to magnetic flux saturation on the core unit 120, resulting in a weakened magnetic field and reduced motor performance, failing to meet requirements. Therefore, only when the maximum depth H of the groove 122 and the maximum width W of the core unit 120 satisfy 1 / 3 ≤ H / W ≤ 2 / 3 can manufacturing costs be reduced while maintaining motor performance.

[0065] It should be noted that when the included angle α is an obtuse angle, refer to... Figure 4 The intersection of the first wall 124 and the second wall 125 is located on the center line 123 and is defined as the intersection point G. Therefore, the maximum depth H of the groove 122 is the shortest distance between the maximum circumcircle Q1 and the intersection point G.

[0066] In other embodiments, when the included angle α is an acute angle, refer to Figure 5 The end of the first wall 124 near the axis of rotation and the end of the second wall 125 near the axis of rotation are connected by an arc surface S. The arc surface S is defined to have an intersection point F with the center line 123. The maximum depth H of the groove 122 is the shortest distance between the maximum circumcircle Q1 and the intersection point F.

[0067] Reference Figure 2 The core unit 120 is provided with positioning holes 126, which penetrate both ends of the core unit 120 along the direction of the rotation axis. It can be understood that the core unit 120 is composed of multiple lamination units 111 stacked along the rotation axis. During the lamination installation process, the positioning holes 126 can be used to position the multiple lamination units 111, improving positioning accuracy and installation efficiency. On the other hand, during the installation of the core unit 120 and the permanent magnet 101, the positioning holes 126 can be used to position the rotor core 100 as a whole; simultaneously, during the motor assembly process, the positioning holes 126 can be used to position the rotor assembly as a whole, thereby improving installation accuracy and efficiency.

[0068] The core unit 120 is provided with injection holes 127, which penetrate both ends of the core unit 120 along the direction of the rotation axis. It can be understood that during the injection molding process, the core unit 120 together with the pre-arranged permanent magnets 101 are placed into the mold, and the molten injection molding material is injected into the mold cavity by the injection molding machine. After injection molding is completed and cooled, the high temperature and high pressure plastic will cool and solidify rapidly, wrapping the core unit 120 and the permanent magnets 101 to form a plastic coating covering the rotor core 100. The plastic coating can simultaneously cover the outer wall along its radial direction and the two end walls along the direction of the rotation axis of the rotor core 100. At the same time, the plastic coating also fills the injection holes 127, thereby ensuring a stable connection between the core unit 120 and the permanent magnets 101.

[0069] Understandably, the positioning hole 126 and the injection hole 127 are both located on the center line 123. This allows the positioning hole 126 and the injection hole 127 to remove the same area on both sides of the core unit 120 along the center line 123, thus having the same effect on the magnetic field and minimizing the impact on the magnetic field. This avoids vibration during motor operation caused by uneven magnetic field distribution, maintaining motor performance. Simultaneously, the positioning hole 126 and the injection hole 127 being located on the center line 123 simplifies the structure of the lamination unit 111. When the lamination units 111 are stacked to form the core unit 120, there is no need to distinguish the installation direction, preventing incorrect installation that could prevent the positioning hole 126 or the injection hole 127 from penetrating both ends of the rotor core 100. This reduces the product defect rate, simplifies installation operations, and improves installation efficiency.

[0070] The motor according to a second aspect embodiment of the present invention includes the rotor assembly of the first aspect embodiment of the present invention, and further includes a stator assembly 140, with the rotor assembly wound around the outer periphery of the stator assembly 140. Because the motor employs all the technical solutions of the rotor assembly of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0071] The household appliance of the third aspect of the present invention includes the motor of the second aspect of the present invention. Since the household appliance adopts all the technical solutions of the motor of the above-described embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above-described embodiments.

[0072] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A rotor assembly for rotation about an axis of rotation, characterised in that, The rotor core comprises a plurality of core units arranged at intervals along a circumferential direction of the rotor core, each core unit being composed of a plurality of lamination units arranged in a direction of the rotation axis, and a mounting groove being defined between two adjacent core units, and a recess being arranged on a side of the core unit away from the rotation axis. A plurality of permanent magnets are arranged in the mounting grooves. The recess extends through both ends of the rotor core in the direction of the rotation axis.

2. The rotor assembly of claim 1, wherein: The core unit has a center line arranged in a radial direction of the rotor core, and a side wall of the recess comprises a first wall surface and a second wall surface arranged oppositely along the circumferential direction, and the first wall surface and the second wall surface are symmetrically arranged relative to the center line.

3. The rotor assembly of claim 1, wherein: The first wall surface and the second wall surface both extend to the center line, and an included angle between the first wall surface and the second wall surface is not less than 90°.

4. The rotor assembly of claim 3, wherein: The included angle between the first wall surface and the second wall surface is an acute angle, and an end of the first wall surface close to the rotation axis is connected to an end of the second wall surface close to the rotation axis through an arc surface.

5. The rotor assembly of claim 3, wherein: In the radial direction of the rotor core, a maximum depth of the recess is H, and a maximum width of the core unit is W, and the following condition is satisfied: 1 / 3≤H / W≤2 / 3.

6. The rotor assembly of claim 1, wherein: The core unit comprises a first limiting portion and a second limiting portion arranged on the same side along the circumferential direction, and the first limiting portion and the second limiting portion are both arranged protruding towards the mounting groove, and the first limiting portion and the second limiting portion abut against two ends of the permanent magnet in the radial direction of the rotor core, respectively.

7. The rotor assembly of claim 1, wherein: The first limiting portion and the second limiting portion are both provided with two, and the two first limiting portions are arranged on two sides of the core unit along the circumferential direction, respectively, and the two second limiting portions are arranged on two sides of the core unit along the circumferential direction, respectively.

8. The rotor assembly of claim 7, wherein: The core unit is provided with a positioning hole extending through both ends of the core unit in the direction of the rotation axis.

9. The rotor assembly of claim 1, wherein: The core unit is provided with an injection hole extending through both ends of the core unit in the direction of the rotation axis.

10. The rotor assembly of claim 1, wherein: The rotor assembly further comprises a plastic body, and part of the plastic body fills the injection hole.

11. The rotor assembly of claim 10, wherein: The stator assembly comprises:

12. An electric machine characterized by The rotor assembly according to any one of claims 1 to 11, and the rotor assembly is arranged around an outer periphery of the stator assembly. The motor according to claim 12. ​ 13. Household appliance, characterized in that ​

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