The rotor of the motor and the motor

Abstract

The present invention discloses a rotor of an electric machine and the electric machine. The rotor includes: a rotor core; a plurality of permanent magnet groups, which are installed on the rotor core and distributed circumferentially along the rotor core. Each permanent magnet group includes an outer permanent magnet and an inner permanent magnet with a series magnetic circuit. In the radial direction of the rotor core, the inner permanent magnet is located on the side closer to the axis of the rotor core of the corresponding outer permanent magnet. Among them, the coercivity of the outer permanent magnet is greater than that of the inner permanent magnet, and the inner permanent magnet is a cerium-containing neodymium iron boron permanent magnet and / or a heavy-rare-earth-free neodymium iron boron permanent magnet. For the rotor of the electric machine according to the embodiment of the present invention, by using the inner permanent magnet as a cerium-containing neodymium iron boron permanent magnet and / or a heavy-rare-earth-free neodymium iron boron permanent magnet, and the coercivity of the outer permanent magnet is greater than that of the inner permanent magnet, the cost of the electric machine is greatly reduced, the performance of the electric machine is ensured, and at the same time, the demagnetization resistance performance of the permanent magnet is taken into account.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and more particularly, to a rotor of a motor and a motor. Background Art

[0002] Permanent magnets account for a very large proportion of the cost of motors. Neodymium-iron-boron permanent magnets are the most commonly used high-performance permanent magnets, but rare earths, especially heavy rare earths, are expensive and their prices are unstable.

[0003] In some related technologies, a scheme of mixing ferrite and neodymium-iron-boron permanent magnets is adopted to reduce costs. However, ferrite will greatly reduce the performance of the motor and cannot be used in high-performance motors. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, an object of the present invention is to provide a rotor of a motor, which takes into account both cost reduction and demagnetization resistance performance.

[0005] Another object of the present invention is to provide a motor having the above rotor.

[0006] The rotor of the motor according to an embodiment of the present invention includes: a rotor core; a plurality of permanent magnet groups, the plurality of permanent magnet groups are mounted on the rotor core and are circumferentially distributed along the rotor core, and each permanent magnet group includes an outer permanent magnet and an inner permanent magnet connected in magnetic circuit series. In the radial direction of the rotor core, the inner permanent magnet is located on the side closer to the axis of the rotor core of the corresponding outer permanent magnet, wherein the coercivity of the outer permanent magnet is greater than the coercivity of the inner permanent magnet, and the inner permanent magnet is a cerium-containing neodymium-iron-boron permanent magnet and / or a heavy-rare-earth-free neodymium-iron-boron permanent magnet.

[0007] The rotor of the motor according to an embodiment of the present invention, by using a cerium-containing neodymium-iron-boron permanent magnet and / or a heavy-rare-earth-free neodymium-iron-boron permanent magnet as the inner permanent magnet, and the coercivity of the outer permanent magnet is greater than the coercivity of the inner permanent magnet, greatly reduces the cost of the motor, ensures the performance of the motor, and at the same time takes into account the demagnetization resistance performance of the permanent magnet.

[0008] In addition, the rotor of the motor according to the above embodiment of the present invention may further have the following additional technical features:

[0009] According to some embodiments of the present invention, the outer permanent magnet is a neodymium-iron-boron permanent magnet; the cerium content of the cerium-containing neodymium-iron-boron permanent magnet is greater than or equal to 1%.

[0010] According to some embodiments of the present invention, the intrinsic coercivity of the outer permanent magnet is greater than or equal to 120% of the intrinsic coercivity of the inner permanent magnet.

[0011] According to some embodiments of the present invention, the ratio of the remanent flux density of the inner permanent magnet to that of the outer permanent magnet is 70% to 130%.

[0012] According to some embodiments of the present invention, on a cross-section perpendicular to the axial direction of the rotor core, the outer permanent magnet includes at least one first sub-permanent magnet, the first sub-permanent magnet is strip-shaped and has a thickness of H1, the inner permanent magnet includes at least one second sub-permanent magnet, the second sub-permanent magnet is strip-shaped and has a thickness of H2, wherein 1 ≤ H2 / H1 ≤ 3.

[0013] According to some embodiments of the present invention, on a cross-section perpendicular to the axial direction of the rotor core, the outer permanent magnet includes at least one first sub-permanent magnet, the first sub-permanent magnet is strip-shaped and the total length of the at least one first sub-permanent magnet is L1, the inner permanent magnet includes at least one second sub-permanent magnet, the second sub-permanent magnet is strip-shaped and the total length of the at least one second sub-permanent magnet is L2, wherein 1 ≤ L2 / L1 ≤ 2.

[0014] According to some embodiments of the present invention, the rotor core is provided with a plurality of slot groups, and each slot group includes a first installation slot for installing the outer permanent magnet and a second installation slot for installing the inner permanent magnet.

[0015] According to some embodiments of the present invention, on a cross-section perpendicular to the axial direction of the rotor core, the first installation slot includes a first slot body, and the first slot body extends perpendicular to the radial line of the rotor core or extends obliquely to the radial direction of the rotor core.

[0016] According to some embodiments of the present invention, on a cross-section perpendicular to the axial direction of the rotor core, the first installation slot includes two first slot bodies, the two first slot bodies are close to each other at one end along the radial direction of the rotor core and away from each other at the other end, and the included angle α on the side of the two first slot bodies facing away from the center of the rotor core, and the number of poles of the rotor is P, wherein 90 ≤ α ≤ 180° + 180° / P, 4 ≤ P ≤ 30.

[0017] According to some embodiments of the present invention, on a cross-section perpendicular to the axial direction of the rotor core, the second installation slot includes two second slot bodies, the two second slot bodies are close to each other at the inner end along the radial direction of the rotor core, away from each other at the outer end along the radial direction of the rotor core, and the included angle β is 90° to 160°.

[0018] According to some embodiments of the present invention, in a cross-section perpendicular to the axial direction of the rotor core, the first installation groove includes at least three first groove bodies sequentially connected along the circumferential direction of the rotor core. For the two first groove bodies located at both ends, their radially inner ends along the radial direction of the rotor core are close to each other, and their radially outer ends are far from each other. The second installation groove includes at least three second groove bodies sequentially connected along the circumferential direction of the rotor core. For the two second groove bodies located at both ends, their radially inner ends along the radial direction of the rotor core are close to each other, and their radially outer ends are far from each other.

[0019] According to some embodiments of the present invention, the included angle between the first groove bodies at both ends and the first groove body in the middle is γ, and the included angle between the second groove bodies at both ends and the second groove body in the middle is δ. The number of poles of the rotor is P, where γ = 90° + 180° / P ± 5°, δ = 90° + 180° / P ± 5°, and 4 ≤ P ≤ 30.

[0020] According to some embodiments of the present invention, in a cross-section perpendicular to the axial direction of the rotor core, the number of the first groove bodies is equal to that of the second groove bodies, and they are arranged in parallel one by one.

[0021] According to some embodiments of the present invention, in each groove group, the minimum distance between the first installation groove and the second installation groove is greater than or equal to 2 mm.

[0022] According to some embodiments of the present invention, the first installation groove includes a plurality of first groove bodies, and the plurality of first groove bodies are communicated with each other or blocked by a magnetic isolation bridge; the second installation groove includes a plurality of second groove bodies, and the plurality of second groove bodies are communicated with each other or blocked by a magnetic isolation bridge.

[0023] According to some embodiments of the present invention, the rotor core is further provided with a plurality of through holes, and the through holes are located on one side far from the axis of the rotor core at the closer ends of two adjacent second installation grooves.

[0024] The motor according to an embodiment of the present invention includes a rotor of the motor according to an embodiment of the present invention.

[0025] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0027] Figure 1 is a schematic structural diagram of a rotor according to a first embodiment of the present invention;

[0028] Figure 2 is Figure 1 A partially enlarged structural schematic diagram of the area between the center lines OA1 and OA2;

[0029] Figure 3 is a structural schematic diagram of a rotor according to the second embodiment of the present invention;

[0030] Figure 4 is Figure 3 A partially enlarged structural schematic diagram of the area between the center lines OB1 and OB2;

[0031] Figure 5 is a structural schematic diagram of a rotor according to the third embodiment of the present invention;

[0032] Figure 6 is Figure 5 A partially enlarged structural schematic diagram of the area between the center lines OC1 and OC2;

[0033] Figure 7 is a structural schematic diagram of a rotor according to the fourth embodiment of the present invention;

[0034] Figure 8 is Figure 7 A partially enlarged structural schematic diagram of the area between the center lines OD1 and OD2.

[0035] Reference numerals:

[0036] Rotor 100; Stator 200; Motor 1000;

[0037] Rotor core 10; Rotor hole 101; Slot group 11; First mounting groove 12; First slot body 121; Second mounting groove 13; Second slot body 131; Through hole 14;

[0038] Permanent magnet group 20; Outer permanent magnet 21; First sub-permanent magnet 211; Inner permanent magnet 22; Second sub-permanent magnet 221. Detailed description of the specific implementation mode

[0039] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where 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 drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0040] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0041] In the description of the present invention, the "first feature" and "second feature" may include one or more of such features. The meaning of "a plurality" is two or more. The first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may also include the first and second features not being in direct contact but being in contact through additional features therebetween. The first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature.

[0042] The rotor 100 of the motor according to an embodiment of the present invention will be described below with reference to the drawings. Optionally, the motor may be a permanent magnet synchronous motor.

[0043] Refer to Figures 1-8 As shown, the rotor 100 of the motor according to an embodiment of the present invention may include: a rotor core 10 and a plurality of permanent magnet groups 20.

[0044] Specifically, the plurality of permanent magnet groups 20 are mounted on the rotor core 10, and the plurality of permanent magnet groups 20 are distributed along the circumferential direction of the rotor core 10, and each permanent magnet group 20 corresponds to one magnetic pole of the rotor 100.

[0045] It should be noted that the number of the permanent magnet groups 20 may be an even number and can be set according to actual situations, including but not limited to Figures 1-8 the eight permanent magnet groups 20 shown in, and in other embodiments, it may also be four, six or ten permanent magnet groups 20, etc. The even number of permanent magnet groups 20 may be symmetrically mounted about the central axis of the rotor core 10.

[0046] Continuing to refer to Figures 1-8 As shown, each permanent magnet group 20 may include an inner layer permanent magnet 22 and an outer layer permanent magnet 21, and the magnetization directions of the inner layer permanent magnet 22 and the outer layer permanent magnet 21 in the same group are the same. Thus, in the magnetic circuit, the inner layer permanent magnet 22 and the outer layer permanent magnet 21 may be in a series relationship.

[0047] In the radial direction of the rotor core 10, the inner-layer permanent magnet 22 is located inside the corresponding outer-layer permanent magnet 21. In other words, the inner-layer permanent magnet 22 is located on the side closer to the axis of the rotor core 10 of the corresponding outer-layer permanent magnet 21. In still other words, the inner-layer permanent magnet 22 is located on the side closer to the rotor hole 101 of the corresponding outer-layer permanent magnet.

[0048] The inner-layer permanent magnet 22 and the outer-layer permanent magnet 21 are spaced apart in the radial direction, forming a double-layer permanent magnet structure. The double-layer permanent magnet structure enables the permanent magnets to have larger lengths and widths in the radial cross-section, and more permanent magnets can be arranged within a certain space to improve the performance of the motor.

[0049] Among them, the inner-layer permanent magnet 22 is at least one of a cerium-containing neodymium iron boron permanent magnet and a heavy-rare-earth-free neodymium iron boron permanent magnet. That is to say, the inner-layer permanent magnet 22 can reduce costs by at least one of reducing the amount of neodymium and reducing the amount of heavy rare earths, while reducing the damage to the ecological environment.

[0050] For example, in some embodiments, the inner-layer permanent magnet 22 can be a cerium permanent magnet (i.e., a cerium iron boron permanent magnet), a cerium-rich permanent magnet (i.e., a permanent magnet containing neodymium iron boron and cerium iron boron). In other words, in the process of producing permanent magnets, cerium with low price and high reserves is used to at least partially replace high-price neodymium to produce permanent magnets, significantly reducing the price of permanent magnets. However, the remanent flux density of the cerium permanent magnet and the cerium-rich permanent magnet is high, which can be comparable to that of the N45 neodymium iron boron permanent magnet, facilitating the improvement of the performance of the motor and meeting the usage requirements of high-performance motors.

[0051] It can be understood that since the content of cerium element in the impurities is very low and cannot play the role of reducing costs and increasing the remanent flux density, the cerium element contained in the impurities needs to be ignored in the material description in this application.

[0052] In some specific embodiments, the cerium content (weight content) in the cerium-containing neodymium iron boron permanent magnet is greater than or equal to 1%. Within the above ratio range, the effect of reducing the neodymium content is more obvious, thus more significantly reducing the production cost, and the inner-layer permanent magnet 22 can provide a high remanent flux density to improve the performance of the motor.

[0053] It should be noted that the cerium-containing neodymium iron boron permanent magnet may contain heavy rare earths or may not contain heavy rare earths; the heavy-rare-earth-free neodymium iron boron permanent magnet may also contain cerium.

[0054] For example, in some embodiments, the inner permanent magnet 22 may be a neodymium-iron-boron permanent magnet containing light rare earths or a cerium-rich neodymium-iron-boron permanent magnet without heavy rare earths. Compared with heavy rare earths, light rare earths have a lower price and higher reserves, which can reduce production costs, and their prices are stable and the supply is stable. The cerium-rich neodymium-iron-boron permanent magnet with cerium partially replacing neodymium can further significantly reduce costs. Moreover, the neodymium-iron-boron permanent magnet without heavy rare earths has the characteristic of a relatively high remanent flux density, so as to avoid a significant reduction in the performance of the motor and maximize the output torque capacity of the motor.

[0055] It can be understood that heavy rare earths and light rare earths are defined with gadolinium as the boundary. The seven elements of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium before gadolinium are light rare earth elements, also known as cerium-group rare earth elements; gadolinium and the nine elements of terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium after gadolinium are called heavy rare earth elements, also known as yttrium-group rare earth elements.

[0056] In addition, the applicant has found that the neodymium-iron-boron permanent magnet containing cerium and the neodymium-iron-boron permanent magnet without heavy rare earths will reduce the coercivity to a certain extent and have poor demagnetization resistance. And an air gap is formed between the rotor 100 and the stator 200 of the motor, and demagnetization usually first occurs in the part close to the air gap, that is, the outer part far from the rotor hole 101.

[0057] Therefore, in the embodiments of the present invention, the coercivity of the outer permanent magnet 21 can be greater than that of the inner permanent magnet 22, and the rotor 100 including the inner permanent magnet 22 and the outer permanent magnet 21 forms a series magnetic circuit double-layer hybrid permanent magnet type rotor. The outer permanent magnet 21 close to the air gap side has a larger coercivity and high demagnetization resistance, and the inner permanent magnet 22 with a smaller coercivity is located on the side of the outer permanent magnet 21 far from the air gap, so that the inner permanent magnet 22 is subjected to a much smaller external magnetic field than the outer permanent magnet 21. By arranging the positions, the problem of easy demagnetization of the cerium-containing neodymium-iron-boron permanent magnet and the neodymium-iron-boron permanent magnet without heavy rare earths is improved. The inner permanent magnet 22 can use a low-coercivity product without demagnetization, and the outer permanent magnet 21 is used to protect the low-coercivity inner permanent magnet 22 to reduce the demagnetization risk, which can meet the usage requirements of high-load working conditions and can be applied to high-performance motors.

[0058] Thus, by the outer permanent magnet 21 having a larger coercivity, the rotor 100 of the motor has good demagnetization resistance. At the same time, the inner permanent magnet 22 has a lower coercivity but uses a cerium-containing neodymium-iron-boron permanent magnet and a neodymium-iron-boron permanent magnet without heavy rare earths with a relatively high remanent flux density. On the basis of ensuring the performance of the motor, the manufacturing cost of the motor can be greatly reduced, and at the same time, the requirement for the external magnetic field strength for the overall saturation magnetization of the rotor 100 is reduced.

[0059] In some embodiments, the outer permanent magnet 21 can be a neodymium iron boron permanent magnet. For example, it can be a neodymium iron boron permanent magnet containing heavy rare earths, a neodymium iron boron permanent magnet containing light rare earths, etc., as long as it meets the requirement of having a coercivity greater than that of the inner permanent magnet 22.

[0060] The rotor 100 of the motor according to the embodiment of the present invention greatly reduces the cost of the motor, ensures the performance of the motor, and at the same time takes into account the demagnetization resistance performance of the permanent magnet.

[0061] In some embodiments of the present invention, the intrinsic coercivity of the outer permanent magnet 21 can be greater than or equal to 120% of the intrinsic coercivity of the inner permanent magnet 22. The performance of the outer permanent magnet 21 is better, thereby maximizing the performance of the motor.

[0062] In some embodiments, the intrinsic coercivity of the outer permanent magnet 21 can be less than or equal to 300% of the intrinsic coercivity of the inner permanent magnet 22. Within the above ratio range, the demagnetization resistance effect can be ensured, and at the same time, the cost of the outer permanent magnet 21 can be prevented from being too high.

[0063] For example, in some specific embodiments, the ratio of the intrinsic coercivity of the outer permanent magnet 21 to the intrinsic coercivity of the inner permanent magnet 22 can be 120%, 150%, 200%, 220%, 250%, 280%, etc.

[0064] In some embodiments of the present invention, the ratio of the remanent flux density of the inner permanent magnet 22 to the remanent flux density of the outer permanent magnet 21 can be 70% - 130%. On the one hand, the remanent flux density of the inner permanent magnet 22 is made larger to improve the performance of the rotor 100 and meet the requirements of high-performance motors. On the other hand, it is avoided that the remanent flux density of the inner permanent magnet 22 is too large, resulting in an increase in cost. Within the above size range, the dual requirements of high performance and low cost are taken into account.

[0065] In some embodiments of the present invention, as Figures 1-8 shown, in a cross-section perpendicular to the axis of the rotor core 10, the outer permanent magnet 21 includes at least one first sub-permanent magnet 211, and the first sub-permanent magnet 211 is strip-shaped. The inner permanent magnet 22 includes at least one second sub-permanent magnet 221, and the second sub-permanent magnet 221 is strip-shaped. In other words, the outer permanent magnet 21 can be a single piece or segmented, and the inner permanent magnet 22 can be a single piece or segmented. The overall structure is simpler and easier to process. The segmented setting is beneficial to reducing the eddy current inside the permanent magnet and reducing the loss.

[0066] For example, in as Figures 1-6In the illustrated example, the outer permanent magnet 21 includes two first sub-permanent magnets 211, and the two first sub-permanent magnets 211 are arranged in a straight line or a V shape. The inner permanent magnet 22 includes two second sub-permanent magnets 221, and the two second sub-permanent magnets 221 are arranged in a V shape, so that the outer permanent magnet 21 can be located within the region surrounded by the inner permanent magnet 22. As Figure 7 and Figure 8 shown, the outer permanent magnet 21 includes four first sub-permanent magnets 211, and the four first sub-permanent magnets 211 are arranged in a U shape. The inner permanent magnet 22 includes four second sub-permanent magnets 221, and the four second sub-permanent magnets 221 are arranged in a U shape, so that the outer permanent magnet 21 can be located within the region surrounded by the inner permanent magnet 22.

[0067] In addition, as Figure 2 shown, the thickness of the strip-shaped first sub-permanent magnet 211 is H1, and the thickness of the strip-shaped second sub-permanent magnet 221 is H2. Among them, the thickness of the second sub-permanent magnet 221 is greater than the thickness of the first sub-permanent magnet 211, and 1 ≤ H2 / H1 ≤ 3. For example, in some specific embodiments, H2 / H1 can be 1.2, 1.5, 1.8, 2, 2.3, 2.5, 2.8, etc. For the hybrid excitation design, the demagnetization magnetic field of the inner permanent magnet 22 is reduced by 10% to 50%, and the coercivity of the outer permanent magnet 21 can reach up to 3 times the coercivity of the inner permanent magnet 22. By making the thickness of the inner permanent magnet 22 greater than the thickness of the outer permanent magnet 21 and the thickness ratio within the above range, the inner permanent magnet 22 can be matched with the outer permanent magnet 21.

[0068] As Figures 1-8 shown, in the embodiment where the outer permanent magnet 21 includes at least one strip-shaped first sub-permanent magnet 211 on the cross-section perpendicular to the axial direction of the rotor core 10, the total length of all the first sub-permanent magnets 211 included in the outer permanent magnet 21 is L1, that is, the sum of the lengths of each first sub-permanent magnet 211 is L1. In the embodiment where the inner permanent magnet 22 includes at least one strip-shaped second sub-permanent magnet 221, the total length of all the second sub-permanent magnets 221 included in the inner permanent magnet 22 is L2, that is, the sum of the lengths of each second sub-permanent magnet 221 is L2.

[0069] Taking Figure 2 as an example, the outer permanent magnet 21 includes two first sub-permanent magnets 211 arranged in a straight line, and the distance between the mutually remote ends of the two first sub-permanent magnets 211 is L1. The inner permanent magnet 22 includes two second sub-permanent magnets 221 arranged in a V shape, and the lengths of the two second sub-permanent magnets 221 are L21 and L22 respectively, and L2 = L21 + L22.

[0070] Taking Figure 4For example, the outer permanent magnet 21 includes two first sub-permanent magnets 211 arranged in a V shape. The lengths of the two first sub-permanent magnets 211 are L11 and L12 respectively, and L1 = L11 + L12.

[0071] In addition, in some embodiments, L1 and L2 satisfy: 1 ≤ L2 / L1 ≤ 2. Within the above-mentioned dimensional ratio range, the remanence performance of the inner permanent magnet 22 can be utilized to provide more permanent magnetic fields for the motor, improve the performance of the motor, and avoid reducing the mechanical strength of the rotor core 10 due to the excessive length of the inner permanent magnet 22.

[0072] The slot structure of the rotor 100 according to an embodiment of the present invention will be described below with reference to the drawings.

[0073] In some embodiments of the present invention, as Figures 1-8 shown, the rotor core 10 is provided with a plurality of slot groups 11. Each slot group 11 may include a first installation slot 12 and a second installation slot 13. Among them, the outer permanent magnet 21 may be installed in the first installation slot 12, and the inner permanent magnet 22 may be installed in the second installation slot 13. The permanent magnet embedded installation method is convenient for installation and fixation, and the spaced first installation slot 12 and second installation slot 13 enable the inner permanent magnet 22 and the outer permanent magnet 21 to be spaced apart.

[0074] In a cross-section perpendicular to the axial direction of the rotor core 10, the shapes of the first installation slot 12 and the second installation slot 13 can be flexibly set according to actual situations.

[0075] In some embodiments, in the circumferential direction of the rotor core 10, the distance between the two ends of the first installation slot 12 is less than the distance between the two ends of the second installation slot 13, so that the opening width of the second installation slot 13 is greater than that of the first installation slot 12, which is beneficial to forming a magnetic circuit series relationship between the inner permanent magnet 22 and the outer permanent magnet 21 and improving the utilization rate of the permanent magnet.

[0076] In some embodiments, an installation area is defined between the second installation slot 13 and the outer peripheral surface of the rotor core 10. The installation area is located on the side of the second installation slot 13 facing away from the rotor hole 101, and the first installation slot 12 is located in this area, so that the mutually connected outer permanent magnets 21 are closer to the air gap side than the inner permanent magnets 22, thereby achieving the effect of anti-demagnetization.

[0077] In addition, the first installation slot 12 and the second installation slot 13 may both have a symmetry axis, and the symmetry axes of the two installation slots coincide. In other words, the first installation slot 12 is symmetric about the symmetry axis of the second installation slot 13 to improve the effect of preventing the inner permanent magnet 22 from demagnetizing.

[0078] In some embodiments, in a cross-section perpendicular to the axial direction of the rotor core 10, as Figures 1-8As shown, the first mounting groove 12 may include at least one first groove body 121, and the outer permanent magnet 21 may be mounted in the first groove body 121. For example, the outer permanent magnet 21 may include a plurality of magnetic steels arranged in one-to-one correspondence with the first groove body 121. In a cross-section perpendicular to the axial direction of the rotor core 10, the second mounting groove 13 may include a plurality of second groove bodies 131, and the inner permanent magnet 22 may be mounted in the second groove body 131. For example, the inner permanent magnet 22 may include a plurality of magnetic steels arranged in one-to-one correspondence with the second groove body 131. The large size of the inner permanent magnet 22 is beneficial to improving the motor performance and the utilization rate of the permanent magnet, and has little impact on the manufacturing cost of the rotor 100.

[0079] As Figure 1 and Figure 2 shown, in a cross-section perpendicular to the axial direction of the rotor core 10, the first mounting groove 12 may include one first groove body 121, and the first groove body 121 may be arranged in a straight line. For example, the first groove body 121 may extend perpendicular to the radial line of the rotor core 10. In other words, the connection line between the midpoint of the first groove body 121 and the center point of the rotor core 10 is oa, and the connection line between the midpoints of the two ends of the length of the first groove body 121 is bc, and oa is perpendicular to bc; or the first groove body 121 extends obliquely to the radial direction of the rotor core 10, that is, the included angle between oa and bc is an acute angle. Thus, the outer permanent magnet 21 is formed into a straight-line permanent magnet as Figure 1 and Figure 2 shown.

[0080] As Figures 3-6 shown, in a cross-section perpendicular to the axial direction of the rotor core 10, the first mounting groove 12 may include two first groove bodies 121. The two first groove bodies 121 are close to each other at one end along the radial direction of the rotor core 10, and the two first groove bodies 121 are far away from each other at the other end along the radial direction of the rotor core 10, so as to be arranged in a V shape.

[0081] For example, as Figure 4 shown, along the radial direction of the rotor core 10, the outer radial ends of the two first groove bodies 121 are close to each other, and the inner radial ends are far away from each other, so that the first mounting groove 12 is arranged in an inverted V shape; as Figure 6 shown, along the radial direction of the rotor core 10, the inner radial ends of the two first groove bodies 121 are close to each other, and the outer radial ends are far away from each other, so that the first mounting groove 12 is arranged in a positive V shape.

[0082] And, as Figure 2 、 Figure 4 and Figure 6As shown, the included angle α between the outer sides (i.e., the outer sides) of the two first slots 121 facing away from the center of the rotor core 10, and the number of poles P of the rotor 100, where 90 ≤ α ≤ 180° + 180° / P and 4 ≤ P ≤ 30. Further, the range of α can be 150° to 210°. Specifically, in the embodiment where the first slot 121 is a straight slot, as Figure 2 shown, the included angle α can be the included angle between the side walls of the two first slots 121 away from the center of the rotor core 10. In the embodiment where the first slot 121 is a non-straight slot, the connection line of the midpoints at both ends of the length of one first slot 121 is de, and the connection line of the midpoints at both ends of the length of the other first slot 121 is fg, and the included angle between de and fg is α.

[0083] In the above embodiments, the linear or V-shaped arrangement structure of the first installation slot 12 has a reasonable spatial arrangement, which is beneficial to improving the utilization rate of the permanent magnet and improving the motor performance.

[0084] Optionally, the outer-layer permanent magnet 21 in the first installation slot 12 can adopt a segmented structure, which can reduce the eddy current loss of the outer-layer permanent magnet 21, increase the efficiency of the motor, reduce the temperature rise of the rotor 100, and further increase the demagnetization resistance of the rotor 100. Of course, the outer-layer permanent magnet 21 can also be an integral type, which is also within the protection scope of the present invention.

[0085] As Figures 1-6 shown, in the cross-section perpendicular to the axial direction of the rotor core 10, the second installation slot 13 can include two second slots 131. The radially inner ends of the two second slots 131 are close to each other along the radial direction of the rotor core 10, and the radially outer ends of the two second slots 131 are far away from each other along the radial direction of the rotor core 10 to form a V-shaped arrangement. The first installation slot 12 is located at the opening of the V-shaped second installation slot 13 and does not contact the second installation slot 13 (i.e., is spaced apart from the second installation slot 13). Specifically, the connection line of the midpoints at both ends of the length of one second slot 131 is hj, and the connection line of the midpoints at both ends of the length of the other second slot 131 is kl, and the included angle between hj and kl is any value within the range of 90° to 160°, such as 90°, 100°, 120°, 140°, 160°, etc.

[0086] In the above embodiments, the V-shaped arrangement structure of the second installation slot 13, on the one hand, provides sufficient installation space for the first installation slot 12, and the spatial arrangement is reasonable. On the other hand, it makes the size of the inner-layer permanent magnet 22 larger, which is beneficial to improving the utilization rate of the permanent magnet and improving the motor performance.

[0087] As Figure 8As shown, in a cross-section perpendicular to the axial direction of the rotor core 10, the first mounting groove 12 may include at least three first groove bodies 121, and these first groove bodies 121 are sequentially connected along the circumferential direction of the rotor core 10. Among them, the two first groove bodies 121 located at both ends are close to each other at the radially inner ends along the radial direction of the rotor core 10, and the radially outer ends of these two first groove bodies 121 are far from each other, so that the first mounting groove 12 is generally arranged in a U shape.

[0088] In addition, continue to refer to Figure 8 As shown, in a cross-section perpendicular to the axial direction of the rotor core 10, the second mounting groove 13 may include at least three second groove bodies 131, and these second groove bodies 131 are sequentially connected along the circumferential direction of the rotor core 10. And the two second groove bodies 131 located at both ends are close to each other at the radially inner ends along the radial direction of the rotor core 10, and the radially outer ends of these two second groove bodies 131 are far from each other, so that the second mounting groove 13 is generally arranged in a U shape.

[0089] In the above embodiments, the U-shaped arrangement structures of the first mounting groove 12 and the second mounting groove 13, on the one hand, the first mounting groove 12 has sufficient mounting space and the space arrangement is reasonable. On the other hand, it makes the size of the inner permanent magnet 22 larger, which is beneficial to improving the utilization rate of the permanent magnet and improving the motor performance.

[0090] In some embodiments of the present invention, as Figure 8 shown, in the U-shaped arrangement structure, the included angle between the first groove body 121 located at both ends and the first groove body 121 located in the middle is γ, and the included angle between the second groove body 131 located at both ends and the second groove body 131 located in the middle is δ. The number of poles of the rotor 100 is P. Among them, γ = 90° + 180° / P ± 5°, δ = 90° + 180° / P ± 5°, and 4 ≤ P ≤ 30. Within the above angle range, the shapes of the first groove body 121 and the second groove body 131 are more matched, the space can be fully utilized, and it is beneficial to ensure the structural strength of the rotor core 10.

[0091] It should be noted that in the embodiment where the first groove body 121 is a straight groove, as Figure 8 shown, the included angle γ can be the included angle between the side wall of the first groove body 121 located at the end and the first groove body 121 located in the middle. In the embodiment where the first groove body 121 is a non-straight groove, the connection line of the midpoints at both ends of the length of the first groove body 121 located in the middle is de, and the connection line of the midpoints at both ends of the length of the first groove body 121 located at the end is fg, and the included angle between de and fg is γ. According to the above description, the corresponding included angle δ of the second groove body 131 can be understood.

[0092] In some embodiments, as Figure 7 and Figure 8As shown in the figure, the number of the first groove bodies 121 included in the first installation groove 12 is equal to the number of the second groove bodies 131 included in the second installation groove 13, and the first groove bodies 121 and the second groove bodies are arranged in parallel in a one-to-one correspondence. In other words, the extended shapes of the U-shaped structures formed by the multiple first groove bodies 121 and the U-shaped structures formed by the multiple second groove bodies 131 are the same. The first groove body 121 in the middle is parallel to the second groove body 131, and the included angle γ and the included angle δ corresponding to the two U-shaped structures are equal. The parallel U-shaped structures make the processing of the rotor core 10 easier, and enable the outer permanent magnet 21 to better separate the inner permanent magnet 22 from the external magnetic field, reducing the demagnetization risk of the inner permanent magnet 22.

[0093] Optionally, the inner permanent magnet 22 in the second installation groove 13 may adopt a segmented structure, which can reduce the eddy current loss of the inner permanent magnet 22, increase the efficiency of the motor, reduce the temperature rise of the rotor 100, and further increase the demagnetization resistance of the rotor 100.

[0094] In some embodiments, as Figures 1-8 shown, the multiple first groove bodies 121 may be communicated with each other, or the multiple first groove bodies 121 are blocked by a magnetic isolation bridge. In other words, the adjacent two first groove bodies 121 are not communicated and a magnetic isolation bridge is formed. Thus, a magnetic isolation effect is achieved to limit the magnetic circuit distribution.

[0095] In some embodiments, as Figures 1-8 shown, the multiple second groove bodies 131 may be communicated with each other, or the multiple second groove bodies 131 are blocked by a magnetic isolation bridge. In other words, the adjacent two second groove bodies 131 are not communicated and a magnetic isolation bridge is formed. Thus, a magnetic isolation effect is achieved to limit the magnetic circuit distribution.

[0096] In some embodiments of the present invention, as Figures 1-8 shown, in each slot group 11, the minimum distance between the first installation groove 12 and the second installation groove 13 is greater than or equal to 2 mm. On the one hand, the mechanical strength of the rotor core 10 can be ensured, avoiding the fracture of the rotor core 10 under high-speed working conditions, which is beneficial for the rotor 100 to meet the requirements of high-load working conditions. On the other hand, if the distance is too small, the processing difficulty of the rotor core 10 will be greatly increased. Within the above distance range, the processing difficulty can be reduced, the yield can be improved, and the production cost can be reduced.

[0097] In some embodiments, as Figure 8 shown, the first groove body 121 of the first installation groove 12 is parallel to the second groove body 131 of the second installation groove 13, that is, the equal distance between the first installation groove 12 and the second installation groove 13 is equal everywhere, and the corresponding distance value is greater than or equal to 2 mm.

[0098] In other embodiments, as Figure 2As shown, the first installation groove 12 is a linear groove extending tangentially, and the second installation groove 13 is a V-shaped groove. The end of the notch of the V-shaped groove has the smallest distance from the end of the length direction of the linear groove, and is greater than or equal to 2 mm.

[0099] The rotor 100 of an electric motor according to a specific embodiment of the present invention will be described below with reference to the accompanying drawings.

[0100] As Figure 8 shown, the rotor 100 includes a rotor core 10 and eight permanent magnet groups 20. The rotor core 10 is provided with a rotor hole 101 and eight groove groups 11. The eight groove groups 11 are spaced apart along the circumference of the rotor hole 101. Each groove group 11 includes a U-shaped first installation groove 12 and a U-shaped second installation groove 13. The U-shaped first installation groove 12 includes three first groove bodies 121 that are connected in sequence. The U-shaped second installation groove 13 includes three second groove bodies 131 that are connected in sequence. The opening width of the second installation groove 13 is greater than the opening width of the first installation groove 12. The first installation groove 12 is located in the middle of the opening of the U-shaped second installation groove 13, and the second installation groove 13 is symmetrically arranged about the symmetry line of the first installation groove 12. The outer permanent magnet 21 includes four magnetic steels. Two magnetic steels are provided in one of the middle first groove bodies 121, and one magnetic steel is provided in each of the other two first groove bodies 121. The inner permanent magnet 22 includes four magnetic steels. Among them, two magnetic steels are provided in one of the middle second groove bodies 131, and one magnetic steel is provided in each of the other two second groove bodies 131. The inner permanent magnet 22 and the outer permanent magnet 21 form a double-layer permanent magnet structure, which is in a series relationship in the magnetic circuit. In the magnetic circuit during the operation of the motor, the outer magnetic field received by the outer permanent magnet 21 is much greater than that of the inner permanent magnet 22. The inner permanent magnet 22 can use products with low coercivity without demagnetization, while reducing the manufacturing cost of the rotor 100.

[0101] In some embodiments of the present invention, as Figures 1-3 shown, the rotor core 10 may also be provided with a plurality of through holes 14. The plurality of through holes 14 are spaced apart along the circumference of the rotor core 10, and each through hole 14 may be located on the side away from the axis of the rotor core 10 at the adjacent ends of two second installation grooves 13 close to each other, so that each through hole 14 is disposed opposite to the ends of two second installation grooves 13. The through holes 14 can be used to circulate fluids such as air and cooling oil to cool down the rotor 100. The through holes 14 can also be used to position the rotor core 10 during disassembly and assembly, making the disassembly and assembly convenient and fast.

[0102] In addition, by providing the through holes 14, the distance between the two ends of the second installation groove 13 and the air gap is increased, and a magnetic isolation structure, such as a magnetic isolation bridge, can be formed between the through holes 14 and the second installation groove 13 and on the side of the through holes 14 away from the rotor hole 101, so as to further reduce the influence of the outer magnetic field on the inner permanent magnet 22 and avoid demagnetization of the inner permanent magnet 22.

[0103] The motor according to an embodiment of the present invention includes a rotor 100 of the motor according to an embodiment of the present invention. Since the rotor 100 of the motor according to an embodiment of the present invention has the above beneficial technical effects, the cost of the motor according to an embodiment of the present invention is greatly reduced, the performance of the motor is ensured, and at the same time, the anti-demagnetization performance of the permanent magnet is taken into account.

[0104] The other constitutions and operations of the motor according to an embodiment of the present invention are known to those of ordinary skill in the art and will not be described in detail here.

[0105] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0106] In the description of this specification, the descriptions with reference to the terms "embodiment", "specific embodiment", "example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0107] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirits of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A rotor of an electric machine, characterized in that, Comprising: Rotor core; A plurality of permanent magnet groups, the plurality of permanent magnet groups being mounted on the rotor core and distributed circumferentially along the rotor core, each permanent magnet group including an outer permanent magnet and an inner permanent magnet with a series magnetic circuit, and in the radial direction of the rotor core, the inner permanent magnet is located on the side closer to the axis of the rotor core of the corresponding outer permanent magnet, wherein, The coercivity of the outer permanent magnet is greater than that of the inner permanent magnet, and the inner permanent magnet is a cerium-containing neodymium iron boron permanent magnet and / or a heavy-rare-earth-free neodymium iron boron permanent magnet; The outer permanent magnet is a neodymium iron boron permanent magnet; The cerium content of the cerium-containing neodymium iron boron permanent magnet is greater than or equal to 1%; The intrinsic coercivity of the outer permanent magnet is greater than or equal to 120% of the intrinsic coercivity of the inner permanent magnet.

2. The rotor of the electric machine according to claim 1, characterized in that, The ratio of the remanence flux density of the inner permanent magnet to that of the outer permanent magnet is 70% - 130%.

3. The rotor of the motor according to claim 1, characterized in that, On a cross-section perpendicular to the axial direction of the rotor core, the outer permanent magnet includes at least one first sub-permanent magnet, the first sub-permanent magnet is strip-shaped and has a thickness of H1, the inner permanent magnet includes at least one second sub-permanent magnet, the second sub-permanent magnet is strip-shaped and has a thickness of H2, wherein, 1 ≤ H2 / H1 ≤ 3.

4. The rotor of the motor according to claim 1, characterized in that, On a cross-section perpendicular to the axial direction of the rotor core, the outer permanent magnet includes at least one first sub-permanent magnet, the first sub-permanent magnet is strip-shaped and the total length of the at least one first sub-permanent magnet is L1, the inner permanent magnet includes at least one second sub-permanent magnet, the second sub-permanent magnet is strip-shaped and the total length of the at least one second sub-permanent magnet is L2, wherein, 1 ≤ L2 / L1 ≤ 2.

5. The rotor of the electric machine according to any one of claims 1-4, characterized in that The rotor core is provided with a plurality of slot groups, each slot group including a first installation slot for installing the outer permanent magnet and a second installation slot for installing the inner permanent magnet.

6. The rotor of the motor according to claim 5, characterized in that, On a cross-section perpendicular to the axial direction of the rotor core, the first installation slot includes a first slot body, and the first slot body extends perpendicular to the radial line of the rotor core or extends obliquely to the radial direction of the rotor core.

7. The rotor of the electric machine according to claim 5, characterized in that, On a cross-section perpendicular to the axial direction of the rotor core, the first installation slot includes two first slot bodies, the two first slot bodies are close to each other at one end in the radial direction of the rotor core and away from each other at the other end, and the included angle α between the sides of the two first slot bodies facing away from the center of the rotor core, and the number of poles of the rotor is P, wherein, 90 ≤ α ≤ 180° + 180° / P, 4 ≤ P ≤ 30.

8. The rotor of the electric machine according to claim 6 or 7, characterized in that, On a cross-section perpendicular to the axial direction of the rotor core, the second installation slot includes two second slot bodies, the two second slot bodies are close to each other at the inner end in the radial direction of the rotor core, away from each other at the outer end in the radial direction, and the included angle β is 90° - 160°.

9. The rotor of the motor according to claim 5, characterized in that In a cross-section perpendicular to the axial direction of the rotor core, the first installation groove includes at least three first groove bodies sequentially connected along the circumferential direction of the rotor core. The radially inner ends of the two first groove bodies located at both ends are close to each other along the radial direction of the rotor core, and the radially outer ends are far from each other. The second installation groove includes at least three second groove bodies sequentially connected along the circumferential direction of the rotor core. The radially inner ends of the two second groove bodies located at both ends are close to each other along the radial direction of the rotor core, and the radially outer ends are far from each other.

10. The rotor of the motor according to claim 9, characterized in that, The included angle between the first groove bodies located at both ends and the first groove body located in the middle is γ, and the included angle between the second groove bodies located at both ends and the second groove body located in the middle is δ. The number of poles of the rotor is P, where γ = 90° + 180° / P ± 5°, δ = 90° + 180° / P ± 5°, 4 ≤ P ≤ 30.

11. The rotor of the motor according to claim 9, characterized in that, The number of the first groove bodies is equal to that of the second groove bodies, and they are arranged in parallel in one-to-one correspondence.

12. The rotor of the motor according to claim 5, characterized in that, In each groove group, the minimum distance between the first installation groove and the second installation groove is greater than or equal to 2 mm.

13. The rotor of the motor according to claim 5, wherein the first installation groove includes a plurality of first groove bodies, and the plurality of first groove bodies are communicated with each other or blocked by a magnetic isolation bridge; the second installation groove includes a plurality of second groove bodies, and the plurality of second groove bodies are communicated with each other or blocked by a magnetic isolation bridge.

14. The rotor of the motor according to claim 5, characterized in that, The rotor core is further provided with a plurality of through holes, and the through holes are located on one side away from the axis of the rotor core at the closer ends of two adjacent second installation grooves.

15. A motor, characterized in that, It includes the rotor of the motor according to any one of claims 1-14.

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