Rotor assembly, electric motor and compressor

Abstract

The present application discloses a rotor assembly, an electric motor and a compressor. The rotor assembly (100) comprises a rotor core (110), a plurality of first filling bodies (120) and a plurality of second filling bodies (130). The rotor core (110) is provided with a plurality of first mounting slots (111) for mounting the first filling bodies (120), and a plurality of second mounting slots (112) for mounting the second filling bodies (130), wherein the plurality of first mounting slots (111) and the plurality of second mounting slots (112) are alternately arranged in the circumferential direction of the rotor core (110); in the circumferential direction of the rotor core (110), the length of each of the first filling bodies (120) is greater than that of each of the second filling bodies (130); each first filling body (120) is a magnet, and each second filling body (130) is a magnet or is made of a non-magnetic material; and residual magnetism of each first filling body (120) is different from that of each second filling body (130).

Description

Rotor assembly, motor and compressor

[0001] Cross-reference to related applications

[0002] The present application claims priority to Chinese Patent Application No. 202410720103.9, filed on June 4, 2024, and entitled “Rotor assembly, motor and compressor”, and Chinese Patent Application No. 202421268473.5, filed on June 4, 2024, and entitled “Rotor assembly, motor and compressor”, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of motors, and in particular to a rotor assembly, a motor and a compressor. BACKGROUND

[0004] At present, a permanent magnet motor includes a stator assembly and a rotor assembly, the rotor assembly includes a core and a plurality of permanent magnets, the plurality of permanent magnets are arranged in the core, the existing permanent magnet motor generally has the problems of low air gap magnetic field strength and high torque ripple, which leads to poor performance of the motor under high load, low load or high speed working conditions, and the permanent magnets in the motor will have irreversible demagnetization phenomenon when a large current passes through, which reduces the reliability of the motor. SUMMARY

[0005] The present application aims to at least partially solve one of the technical problems existing in the prior art. To this end, the present application provides a rotor assembly, a motor comprising the above rotor assembly and a compressor.

[0006] According to the rotor assembly of the first aspect of the present application, the rotor assembly includes a rotor core and a plurality of first filling bodies and a plurality of second filling bodies. The rotor core is provided with a plurality of first mounting grooves and a plurality of second mounting grooves, and the plurality of first mounting grooves and the plurality of second mounting grooves are staggered along the circumferential direction of the rotor core. The plurality of first filling bodies are respectively arranged in the plurality of first mounting grooves, and the plurality of second filling bodies are respectively arranged in the plurality of second mounting grooves. Along the circumferential direction of the rotor core, the length of the first filling body is greater than the length of the second filling body, the first filling body is a magnet, the second filling body is a magnet or a non-magnetic material, and the residual magnetism of the first filling body is different from the residual magnetism of the second filling body.

[0007] According to some embodiments of the present application, when the second filling body is a magnet, an opening is formed between the second filling body and the side wall of the second mounting groove away from the central axis of the rotor core, and the opening penetrates the rotor core along the axial direction of the rotor core.

[0008] According to some embodiments of the present application, the outer peripheral profile of the rotor core in the axial projection of the rotor core comprises a plurality of groups of curve segments, and each group of the curve segments is symmetrically arranged about the central axis of the first filler in the radial direction of the rotor core.

[0009] According to some embodiments of the present application, each group of the curve segments comprises two first circular arc segments and two second circular arc segments, the two first circular arc segments and the two second circular arc segments are symmetrically arranged about the central axis respectively, the center of the first circular arc segment and the center of the second circular arc segment do not coincide, and the radius of the first circular arc segment is greater than or equal to the radius of the second circular arc segment.

[0010] According to some embodiments of the present application, the rotor core is provided with a shaft hole, the radius of the shaft hole is R0, the cross-sectional shape of the first filler is a rectangle, the length of the first filler in the circumferential direction of the rotor core is W1, the minimum distance between the first filler and the shaft hole is H0, and the number of the first fillers is p, and W1 = 2*(R0+H0)*tan(180° / p) is satisfied.

[0011] According to some embodiments of the present application, the cross-sectional shape of the first filler and the second filler is a rectangle, the length of the second filler in the circumferential direction of the rotor core is W2, the width of the first filler in the radial direction of the rotor core is H1, and the number of the first fillers is p, and 0

[0012] According to some embodiments of the present application, the rotor core is provided with a shaft hole, the radius of the shaft hole is R0, the minimum distance between the first filler and the shaft hole is H0, each group of the curve segments comprises a first circular arc segment and a second circular arc segment, the radius of the first circular arc segment is greater than or equal to the radius of the second circular arc segment, the radius of the first circular arc segment is R1, the width of the opening in the radial direction of the rotor core is H3, the minimum distance from the side wall of the opening to the outer peripheral profile of the rotor core is H4, the width of the second filler is H2, and 0

[0013] According to some embodiments of the present application, the cross-sectional area of the first filler is S1, and the cross-sectional area of the second filler is S2 in the cross section in the radial direction of the rotor core, and 0.1≤S2 / S1≤0.3 is satisfied.

[0014] According to some embodiments of the present application, the residual magnetism of the first filler is Br1, the residual magnetism of the second filler is Br2, and the following is satisfied:

[0015] According to some embodiments of the present application, the outer circumferential wall of the rotor core is provided with a plurality of slots, the plurality of slots are distributed along the circumference of the rotor core and divided into a plurality of slot groups, each of the slot groups comprises at least two slots, and along the radial direction of the rotor core, the plurality of slot groups are arranged opposite to the plurality of first fillers one by one, and at least two slots in each of the slot groups are symmetrically arranged with the middle axis of the first filler along the axial direction of the rotor core as the axis of symmetry.

[0016] According to some embodiments of the present application, the width of the slot is less than or equal to 1 / 8 of the circumference of the rotor core, and the depth of the slot is less than or equal to 1 / 2 of the radius of the rotor core.

[0017] According to the motor of the second aspect of the embodiments of the present application, the motor comprises a stator assembly and the rotor assembly of the first aspect of the embodiments of the present application, the stator assembly is provided with a rotor hole, and the rotor assembly is rotatably arranged in the rotor hole.

[0018] According to the compressor of the third aspect of the embodiments of the present application, the compressor comprises a stator assembly and the rotor assembly of the first aspect of the embodiments of the present application, the stator assembly is provided with a rotor hole, and the rotor assembly is rotatably arranged in the rotor hole.

[0019] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0020] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

[0021] FIG. 1 is a structural schematic view of a rotor assembly and a stator assembly according to some embodiments of the present application;

[0022] FIG. 2 is a structural schematic view of a rotor assembly according to some embodiments of the present application;

[0023] FIG. 3 is a partial schematic view of a rotor core of a rotor assembly according to some embodiments of the present application;

[0024] FIG. 4 is a partial schematic view of a rotor assembly according to some embodiments of the present application;

[0025] FIG. 5 is a structural schematic view of a rotor assembly according to some embodiments of the present application;

[0026] FIG. 6 is a structural schematic view of a rotor assembly according to some embodiments of the present application;

[0027] Fig. 7 is a schematic diagram of a demagnetization region of a rotor assembly of the original scheme;

[0028] Fig. 8 is a schematic diagram of a demagnetization region of a rotor assembly of some embodiments of the present application;

[0029] Fig. 9 is a comparison diagram of torque ripple of the original scheme and torque ripple of some embodiments of the present application.

[0030] Reference signs: rotor assembly 100, rotor core 110, first mounting slot 111, second mounting slot 112, opening 113, shaft hole 114, slot 115, first circular arc segment 116, second circular arc segment 117, first filling body 120, first cut edge 121, second cut edge 122, second filling body 130; stator assembly 200, stator core 210, rotor hole 211, stator slot 212. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments described below are examples for explaining the present application and are not intended to limit the present application.

[0032] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0033] In the description of the present application, if there is a description of first, second, etc. for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the sequence of technical features indicated.

[0034] In the description of the present application, unless otherwise explicitly limited, the words such as arrangement, installation, connection, etc. should be understood in a broad sense, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0035] Referring to Fig. 1, a rotor assembly 100 according to an embodiment of the present application is shown, which includes a rotor core 110, a plurality of first filling bodies 120 and a plurality of second filling bodies 130. The plurality of first filling bodies 120 and the plurality of second filling bodies 130 are arranged alternately in the rotor core 110 along the circumferential direction of the rotor core 110, which can also be understood as being staggered along the circumferential direction of the rotor core 110.

[0036] Specifically, referring to FIG. 1 and FIG. 2, the rotor core 110 is in a substantially annular structure, the outer edge profile of the rotor core 110 is substantially circular, the rotor core 110 is provided with an axle hole 114 for mounting the output shaft of the motor. The rotor core 110 has a central axis X1, and in operation, the rotor core 110 can rotate around the central axis X1. Referring to FIG. 4, the rotor core 110 is provided with a first mounting slot 111 and a second mounting slot 112, the first mounting slot 111 is used for mounting a first filler 120, and the second mounting slot 112 is used for mounting a second filler 130. The number of first mounting slots 111 is multiple, and is arranged one-to-one corresponding to the multiple first fillers 120. The number of second mounting slots 112 is also multiple, and is arranged one-to-one corresponding to the multiple second fillers 130. The multiple first mounting slots 111 and the multiple second mounting slots 112 are alternately arranged along the circumferential direction of the rotor core 110, which can also be understood as being staggered arranged along the circumferential direction.

[0037] It should be noted that the first filler 120 is a magnet, which can be understood as a permanent magnet or a magnetic tile, and the first filler 120 can generate a magnetic field. The second filler 130 is a magnet or a non-magnetic material, and the residual magnetism of the first filler 120 is different from that of the second filler 130. The residual magnetism of the first filler 120 is greater than 0. When the second filler 130 is a magnet, which can be understood as a permanent magnet or a magnetic tile, the residual magnetism of the second filler 130 is greater than 0. When the second filler 130 is a non-magnetic material, the residual magnetism of the second filler 130 can be understood as equal to 0. Regarding the size, in the circumferential direction of the rotor core 110, the length of the first filler 120 is greater than that of the second filler 130. It should be noted that the first filler 120 can extend in a straight line direction to form a straight strip shape, or can extend in a circumferential direction to form an arc strip shape. The second filler 130 can extend in a straight line direction to form a straight strip shape, or can extend in a circumferential direction to form an arc strip shape.

[0038] It should be explained that the residual magnetism refers to the magnetization intensity that a magnet can still maintain in the original direction of the external magnetic field after the external magnetic field is removed after the magnet is magnetized to saturation by the external magnetic field. The residual magnetism can be represented by the symbol Br. Generally speaking, the size of the magnetic field intensity of the magnet can be measured by the size of the residual magnetism. The residual magnetism of the first filler 120 is Br1, and the residual magnetism of the second filler 120 is Br2. The residual magnetism of the magnet can be measured by various methods, such as the residual magnetism test method, which uses residual magnetism test instruments such as tesla meter and residual magnetism tester, and can accurately measure the residual magnetism intensity on the magnet.

[0039] In the above embodiments, according to actual working condition requirements, the residual magnetism of the first filler 120 or the second filler 130 can be increased by adjusting the magnetizing process during production and manufacturing, so that the residual magnetism Br1 of the first filler 120 and the residual magnetism Br2 of the second filler 130 are different. Specifically, under the working condition requirement of high load, the residual magnetism of the second filler 130 can be made greater than the residual magnetism of the first filler 120, that is, Br2 is greater than Br1, which can be understood as enhancing the magnetic field of the second filler 130. Since the first filler 120 and the second filler 130 are alternately arranged, the distribution of the magnetic field in space can be optimized, so that the strength of the air gap magnetic field of the motor as a whole is enhanced, and the torque ripple is reduced, which can improve the working performance of the motor. Moreover, since the length of the second filler 130 is less than the length of the first filler 120, the spatial layout is optimized, which can reduce the volume of the motor and improve the power density of the motor. Under the working condition requirement of low load or high speed, the residual magnetism of the second filler 130 can be made less than the residual magnetism of the first filler 120, that is, Br2 is less than Br1, which can be understood as weakening the magnetic field of the second filler 130. Since the first filler 120 and the second filler 130 are alternately arranged, the spatial distribution of the magnetic field will be changed, so that the efficiency of the motor is improved and the speed range is widened. Overall, it can be suitable for working condition requirements of high load, low load or high speed.

[0040] It should be explained that magnetizing refers to magnetizing magnetic substances or increasing the magnetism of magnetic bodies with insufficient magnetism. The process of magnetizing is to place magnetic materials in an external magnetic field, so that the magnetic moments of the magnetic materials are arranged along the direction of the external magnetic field, thereby making the magnetic materials obtain magnetism. The stronger the strength of the additional external magnetic field, the stronger the magnetizing effect on the magnetic body, and the greater the residual magnetism of the magnetic body.

[0041] It can be understood that the magnetizing direction of the first filling body 120 is along the radial direction of the rotor core 110, and the magnetizing direction of the second filling body 130 is along the tangential direction of the rotor core 110, that is, the tangent direction of the rotor core 110. Specifically, the direction indicated by the arrow in FIG. 6 is the magnetizing direction of the first filling body 120 and the second filling body 130, the magnetizing directions of adjacent first filling bodies 120 are opposite, and the magnetizing directions of adjacent second filling bodies 130 are opposite, that is, in the two adjacent first filling bodies 120, the magnetizing direction of one is along the clockwise tangential direction, and the magnetizing direction of the other is along the counterclockwise tangential direction. In the two adjacent second filling bodies 130, the magnetizing direction of one is along the radial direction outward, and the magnetizing direction of the other first filling body 120 is along the radial direction inward, so that two groups of permanent magnets with different magnetic field directions are formed on the rotor core 110, which can reduce the single-pole leakage magnetic of each permanent magnet. Moreover, the magnetic field between the two adjacent first filling bodies 120 forms a series magnetic circuit, and the magnetic field generated by the first filling body 120 and the magnetic field generated by the second filling body 130 form a parallel magnetic circuit, so that the leakage magnetic between the adjacent poles is effectively reduced through the series and parallel combined magnetic circuit structure, the magnetic flux density is improved, the air gap magnetic density of the motor is enhanced, the air gap magnetic field amplitude is improved, the current is smaller under the same load, the line loss is reduced, the harmonic magnetic field is suppressed, and the iron loss is reduced, so that the performance of the motor is improved.

[0042] It can be understood that when a large current passes through the plurality of permanent magnets arranged alternately along the circumferential direction and with different residual magnetisms, irreversible demagnetization phenomenon occurs, which seriously affects the reliability of the motor.

[0043] It should be noted that irreversible demagnetization refers to a phenomenon that a magnet permanently loses part or all of its magnetism under the action of external factors. Even if the external factors are removed, the magnetism of the magnet cannot be restored to the state before demagnetization, which is an irreversible phenomenon. If irreversible demagnetization occurs in the permanent magnet inside the permanent magnet motor, the performance of the motor will be greatly affected, therefore, how to design the internal structure of the motor to improve the irreversible demagnetization of the magnet is very important. There are many external factors that cause irreversible demagnetization, one of which is that when the permanent magnet motor operates under a large current condition, the large current can be understood as a demagnetizing current, the large current will flow through the permanent magnet and generate an opposite magnetic field, which will cancel out the inherent magnetic field of the permanent magnet, resulting in a decrease in the magnetism of the permanent magnet and irreversible demagnetization. If the current is large enough, it may even cause the permanent magnet to completely demagnetize. Especially when a plurality of permanent magnets with different residual magnetisms are arranged alternately along the circumferential direction, this phenomenon is more serious.

[0044] Based on this, referring to FIGS. 2-4, in some embodiments, when the second filling body 130 is a magnet, a through-hole 113 can be arranged on the rotor core 110, the through-hole 113 penetrates the rotor core 110 along the axial direction, the through-hole 113 communicates with the second mounting groove 112, and the through-hole 113 is located between the side wall of the second mounting groove 112 and the second filling body 130. It can be understood that the through-hole 113 is formed after removing part of the material on the side wall of the second mounting groove 112 away from the center axis X1, that is, the through-hole 113 is part of the second mounting groove 112, and the size of the second mounting groove 112 is enlarged. When the second filling body 130 is installed in the second mounting groove 112, the second filling body 130 does not completely fill the second mounting groove 112, and the gap between the second filling body 130 and the side wall of the second mounting groove 112 can be understood as the through-hole 113.

[0045] It can be understood that, since the air gap magnetic resistance at the through-hole 113 is relatively large compared to the magnetic resistance of the rotor core 110, the reverse magnetic field formed by the demagnetizing current is not easy to pass through the through-hole 113, which changes the spatial distribution of the reverse magnetic field, making it not easy for the reverse magnetic field to pass through the second filling body 130, thereby improving the irreversible demagnetization phenomenon of the second filling body 130 when a large current passes through. The anti-irreversible demagnetization capability of the second filling body 130 is enhanced, ensuring that the magnetic field of the second filling body 130 is not easily affected by the demagnetizing current, which can improve the reliability of the motor and ensure stable operation of the motor under large current working conditions.

[0046] For the case where the plurality of first filling bodies 120 and the plurality of second filling bodies 130 are arranged alternately, FIG. 7 shows the demagnetization region distribution state of the first filling body 120 and the second filling body 130 without arranging the through-hole 113 on the rotor core 110. FIG. 8 shows the demagnetization region distribution state of the first filling body 120 and the second filling body 130 after arranging the through-hole 113 on the rotor core 110. Demag-Coef (demagnetization coefficient) is the demagnetization coefficient, which is also called the magnetic permeability coefficient, an important parameter for describing the demagnetization of the magnet. The demagnetization coefficient is defined as the ratio of the magnetic induction intensity to the demagnetization field intensity. The larger the demagnetization coefficient, the more difficult it is for the magnet to be demagnetized. The demagnetization coefficient is in a one-to-one correspondence with different colors, and the distribution area of different colors is used to measure the demagnetization degree of the magnet. The darker the color, the smaller the demagnetization coefficient, and the whiter the color, the larger the demagnetization coefficient. The demagnetization coefficient of the gray area is larger than that of the black area, and the anti-demagnetization capability is stronger. The demagnetization coefficient of the black area is smaller, and the anti-demagnetization capability is weaker. The black area can be understood as the demagnetization region.

[0047] As can be seen by comparing FIG. 7 and FIG. 8, in FIG. 7, without the arrangement of the opening 113, the color on the second filling body 130 gradually changes from gray to black in the radial direction of the rotor core 110 away from the center axis X1, which can be understood as that the demagnetization area of the second filling body 130 is large, especially at the corner position of the second filling body 130 away from the center axis X1, because the reverse magnetic field formed by the demagnetizing current passes through the position with a thinner thickness of the second filling body 130, i.e., the corner position of the second filling body 130, in the minimum magnetic resistance path, which causes the demagnetization phenomenon at the corner position and also causes the anti-demagnetization ability of the corner position of the second filling body 130 to be weak. In FIG. 8, after the arrangement of the opening 113, the demagnetization area on the second filling body 130 is obviously eliminated, especially at the corner position, i.e., the demagnetization coefficient of the second filling body 130 is increased. After analyzing the detailed data, it can be concluded that the demagnetization area is reduced from 7% of the original scheme to 1%, and the anti-demagnetization ability of the second filling body 130 is improved, which can improve the reliability of the motor.

[0048] It should be noted that in some embodiments, the first filling body 120 is made of ferrite material, which can be understood as a ferrite permanent magnet, and the second filling body 130 is a rare earth permanent magnet, which is made of intermetallic compounds composed of rare earth elements and transition metals. The rare earth permanent magnet has the advantages of high magnetic energy product, high coercivity and high working temperature. The high coercivity permanent magnet material is not easy to be magnetized by a large current, thereby improving the anti-demagnetization ability. The rare earth permanent magnet with high magnetic energy product can also generate a stronger magnetic field to improve the working performance of the motor, which is suitable for high load working conditions. The rare earth permanent magnet can be divided into rare earth cobalt permanent magnet, rare earth nickel permanent magnet, rare earth iron boron permanent magnet and rare earth aluminum nickel cobalt permanent magnet according to different materials.

[0049] In some embodiments, because the residual magnetism of the second filling body 130 is greater than that of the first filling body 120, the magnetic field provided by the second filling body 130 is strong enough to make the volume of the second filling body 130 smaller than that of the first filling body 120, thereby reducing the occupied space and being beneficial to the size reduction of the motor, and at the same time, the material cost of the second filling body 130 can be saved.

[0050] Referring to FIG. 2, in some embodiments, the number of the first installation slots 111 is four, the number of the second installation slots 112 is four, the number of the first filling bodies 120 is four, the number of the second filling bodies 130 is four, the first filling bodies 120 extend in a straight line direction and are in a straight strip shape, the four first filling bodies 120 enclose a square structure, the four second filling bodies 130 are respectively located at four corners of the square structure, and the second filling bodies 130 are also in a square structure. In this embodiment, by reasonably configuring the number of the first filling bodies 120 and the second filling bodies 130, the space of the rotor core 110 can be fully utilized, the spatial layout is optimized, the volume of the motor can be reduced, and the power density of the motor is improved.

[0051] It should be noted that, for the first filling body 120, the first filling body 120 is prone to magnetic leakage, and two adjacent first filling bodies 120 are spaced apart to form a magnetic bridge. The magnetic bridge can be understood as part of the structure of the rotor core 110. The magnetic field lines generated by the first filling body 120 will leak through the magnetic bridge, and part of the magnetic field lines will not reach the stator, thereby reducing the utilization rate of the rotor magnetic field and causing a certain attenuation of the air gap magnetic field amplitude. Based on this, referring to FIG. 3, in some embodiments, two adjacent first filling bodies 120 are spaced apart, and the minimum distance between the two adjacent first filling bodies 120 is W0. In order to reduce the magnetic leakage of the first filling body 120, W0 should be as small as possible, but W0 is not 0, thereby forming a support beam between the two adjacent first filling bodies 120, which can improve the structural strength of the rotor core 110 and improve the support effect.

[0052] Referring to FIG. 3, in some embodiments, for two adjacent first filling bodies 120, one of the first filling bodies 120 is provided with a first cut edge 121 at the corner position, and the other first filling body 120 is provided with a second cut edge 122 at the corner position. The first cut edge 121 and the second cut edge 122 can be understood as being formed by cutting part of the structure at the corner position of the first filling body 120. The first cut edge 121 and the second cut edge 122 are close to each other, and the magnetic bridge is located between the first cut edge 121 and the second cut edge 122. W0 of the above embodiment can be understood as the minimum distance from the first cut edge 121 to the second cut edge 122. The first cut edge 121 and the second cut edge 122 can be straight lines and parallel to each other. The extension direction of the first cut edge 121 and the second cut edge 122 can be the same as the length direction of the second filling body 130 in the radial direction. This embodiment can make the two adjacent first filling bodies 120 closer, and after the first cut edge 121 and the second cut edge 122 are provided, the magnetic field space distribution of the first filling body 120 can be optimized, and the magnetic leakage can be reduced.

[0053] Referring to FIG. 3, in some embodiments, the first filler 120 and the second filler 130 are also arranged at intervals, thereby forming a magnetic bridge, the second filler 130 extends into between two adjacent first fillers 120, shortens the distance between the second filler 130 and the first filler 120, which can be understood as shortening the thickness of the magnetic bridge, thereby reducing the magnetic leakage. The minimum distance between the first filler 120 and the second filler 130 is W4, in order to reduce the magnetic leakage of the first filler 120, W4 should be as small as possible, but W4 is not 0, thereby forming a support beam between the two adjacent first fillers 120 and the second filler 130, which can improve the structural strength of the rotor core 110 and improve the support effect.

[0054] Referring to FIGS. 2 and 3, according to some embodiments of the present application, the radius of the shaft hole 114 is R0, and the cross-sectional shape of the first filler 120 is rectangular. In the circumferential direction of the rotor core 110, the length of the first filler 120 is W1. In the radial direction of the rotor core 110, the minimum distance between the first filler 120 and the shaft hole 114 is H0. The number of the first fillers 120 is p, which can be understood as the number of poles of the motor. The above-mentioned various parameters satisfy: W1 = 2 * (R0 + H0) * tan(180° / p). In the present embodiment, the value range of W1 is relatively appropriate, which can utilize the space on the rotor core 110 as much as possible, optimize the distribution of the magnetic field of the first filler 120, and improve the efficiency and power density of the motor.

[0055] Referring to FIGS. 2 and 3, according to some embodiments of the present application, the cross-sectional shape of the first filler 120 and the second filler 130 is rectangular. In the circumferential direction of the rotor core 110, the length of the first filler 120 is W1, the length of the second filler 130 is W2, and the width of the first filler 120 is H1, and the above-mentioned various parameters satisfy: 0 < W2 < 2 * H1 * sin(180° / p). In the present embodiment, the value range of W2 is relatively appropriate, which can utilize the space on the rotor core 110 as much as possible, optimize the distribution of the magnetic field of the second filler 130, and improve the efficiency and power density of the motor.

[0056] It should be noted that in the above-mentioned embodiments, the size of the first filler 120 is designed according to the optimum magnetic energy product, that is, the maximum magnetic flux per unit volume. The magnetic energy product is an index for measuring the ability of a material to store magnetic energy, and the magnetic energy product is defined as the maximum product of the magnetic induction intensity (B) and the corresponding magnetization field (H) of the material in the magnetization process, which is usually measured in units of megagauss- oersted (MGOe). A higher magnetic energy product indicates that the material can store more magnetic energy in a given volume, which can ensure that the magnetic field of the first filler 120 is strong and improve the working performance of the motor.

[0057] In this embodiment, by adjusting the size of the second filler 130, the air gap magnetic field of the motor can be enhanced to a certain extent. Combined with the magnetic flux density-iron loss curve adopted by the motor, it can be ensured that the magnetic flux density in the magnetic circuit of the motor is less than the inflection point value of the curve, thereby realizing the reduction of the volume of the motor, the improvement of the power density, the reduction of the electromagnetic loss of the motor, and the improvement of the efficiency of the motor by more than 1%. At the same time, the saturation effect can also be reduced. Saturation refers to the weakening of the ability of a material to respond to further increases in the magnetic field, and saturation can cause distortion of the magnetic field and reduce the performance of the motor. Working below the inflection point value helps to avoid saturation.

[0058] It should be noted that the magnetic flux density-iron loss curve (also known as B-H curve or hysteresis loop) is a graphical representation of the relationship between magnetic induction (B) and magnetic field strength (H). The inflection point value of the magnetic flux density-iron loss curve refers to the point at which the magnetic flux density-iron loss curve transitions from its initial linear region to its more nonlinear region, which is usually marked by a sudden change in slope.

[0059] According to some embodiments of the present application, along the axial section of the rotor core 110, the cross-sectional area of the first filler 120 is S1, and the cross-sectional area of the second filler 130 is S2, which satisfies: 0.1≤S2 / S1≤0.3. It should be explained that since the length of the first filler 120 in the circumferential direction is greater than the length of the second filler 130, along the axial section of the rotor core 110, S1 will be greater than S2. This embodiment makes the volume distribution ratio of the first filler 120 and the second filler 130 more reasonable, thereby ensuring the performance of the motor while reducing the cost of the motor, improving the performance-price ratio of the motor, and also making the best use of the space on the rotor core 110 to optimize the distribution of the magnetic field of the first filler 120 and the second filler 130, and improve the efficiency and power density of the motor.

[0060] On the basis of the above-mentioned embodiments, the residual magnetism of the first filler 120 is Br1, and the residual magnetism of the second filler 130 is Br2, which satisfies: It should be noted that when the second filler 130 is a non-magnetic material, Br2 is 0. This makes the residual magnetism and cross-sectional area of each filler have a correlation, so that the volume distribution ratio of the first filler 120 and the second filler 130 is more reasonable, thereby ensuring the performance of the motor while reducing the cost of the motor, improving the performance-price ratio of the motor, and also making the best use of the space on the rotor core 110 to optimize the distribution of the magnetic field of the first filler 120 and the second filler 130, and improve the efficiency and power density of the motor.

[0061] It should be noted that when two kinds of magnets with different residual magnetism are arranged alternately in the circumferential direction, it will bring the technical problem of large torque ripple to the motor, and further cause abnormal vibration and noise.

[0062] According to some embodiments of the present application, as shown in FIG. 1, the outer contour line of the rotor core 110 along the axial direction of the rotor core 110 comprises a plurality of curve segments. It can also be understood that the outer contour line of the rotor core 110 is composed of a plurality of curve segments. Specifically, along the circumferential direction of the rotor core 110, the plurality of curve segments are arranged one-to-one corresponding to the plurality of first fillers 120. Alternatively, along the radial direction of the rotor core 110, the plurality of curve segments are arranged one-to-one opposite to the plurality of first fillers 120. It can be understood that, along the radial direction of the rotor core 110, the curve segment is located on the radially outer side, and the first filler 120 is located on the radially inner side. The first filler 120 has a central axis X2, the first filler 120 is a symmetrical structure, the first filler 120 is symmetrical about the central axis X2, and the central axis X2 can be understood as a symmetry line. Since the number of first fillers 120 is multiple, and the plurality of first fillers 120 are arranged along the circumferential direction, the extension direction of the central axis X2 of each first filler 120 is different. Each group of curve segments is arranged symmetrically about the central axis X2 of the first filler 120 corresponding thereto, and the central axis X2 of the first filler 120 can be understood as the symmetry line of the curve segment.

[0063] In the present embodiment, by arranging curve segments on the outer periphery of the rotor core 110, the positions of the curve segments and the first fillers 120 are associated, the distribution of the air gap between the rotor core 110 and the stator core 210 can be changed, the harmonic content in the magnetic flux density waveform of the air gap magnetic field can be reduced by changing the distribution rule of the air gap, the magnetic flux density waveform of the air gap magnetic field tends to be a sinusoidal wave, and the back electromotive force waveform of the motor can tend to be a sinusoidal wave, thereby reducing the torque ripple of the motor.

[0064] In some embodiments, each group of curve segments can include multiple circular arc segments, and the centers of two circular arc segments can be concentric or non-concentric. In other embodiments, each group of curve segments can also include multiple elliptical arc segments or other types of curves or arcs. Each group of curve segments can also include multiple circular arc segments and multiple elliptical arc segments, which are not limited herein.

[0065] According to some embodiments of the present application, as shown in FIG. 2, the curve segment comprises a first circular arc segment 116 and a second circular arc segment 117, the number of the first circular arc segment 116 and the second circular arc segment 117 is two respectively, the two first circular arc segments 116 are symmetrical about the central axis X2, and the two second circular arc segments 117 are symmetrical about the central axis X2. The center of the first circular arc segment 116 is O0, and the center of the second circular arc segment 117 is O1. O0 and O1 are arranged non-concentrically, which can also be understood as the centers of the first circular arc segment 116 and the second circular arc segment 117 do not coincide. Specifically, O0 or O1 can be offset from the central axis X1, one of O0 and O1 has a distance from the central axis X1, or O0 and O1 are both offset from the central axis X1, and O0 and O1 both have a distance from the central axis X1.

[0066] As shown in FIG. 2, in some embodiments, the radius of the first circular arc segment 116 is R1, the radius of the second circular arc segment 117 is R2, the central angle of the first circular arc segment 116 is θ1, and the central angle of the second circular arc segment 117 is θ2. R1 is greater than R2, and θ1 is less than θ2. It can be understood that the arc length of the first circular arc segment 116 is less than the arc length of the second circular arc segment 117, and the first circular arc segment 116 is closer to the central axis X2 than the second circular arc segment 117. It can also be understood that, for a group of curve segments, the second circular arc segment 117, the first circular arc segment 116, the first circular arc segment 116, and the second circular arc segment 117 are sequentially connected along the circumferential direction of the rotor core 110, and the group of curve segments is located between two adjacent second fillers 130. The outer contour line of the rotor core 110 is composed of four groups of the above-mentioned curve segments. In this embodiment, the arrangement of the curve segments is optimized, the effect is good, and the torque ripple of the motor can be further reduced.

[0067] As shown in FIGS. 2 and 3, on the basis of the above-mentioned embodiments, the radius of the shaft hole 114 is R0, the central axis X1 can be understood as the axis of the shaft hole 114, and the minimum distance between the first filler 120 and the shaft hole 114 is H0. In the circumferential direction of the rotor core 110, the length of the second filler 130 is W2, and the length of the opening 113 is W3, which can be less than W2. In the radial direction of the rotor core 110, the width of the second filler 130 is H2, and the width of the opening 113 is H3. The minimum distance from the side wall of the opening 113 to the outer contour line of the rotor core 110 is H4. The above-mentioned parameters satisfy: 0 < H2 < R1-[0.5*W2 / tan(180° / p)+(R0+H0)*cos(180° / p)+H3+H4]. In this embodiment, the center O0 can be located on the central axis X1. In this embodiment, by adjusting the size of the second filler 130, the air gap magnetic field of the motor can be enhanced by a certain amplitude. Combined with the magnetic density-iron loss curve used by the motor, it can be ensured that the magnetic density in the magnetic circuit of the motor is less than the inflection point value of the curve, thereby realizing the reduction of the volume of the motor and the improvement of the power density. At the same time, the electromagnetic loss of the motor is also reduced, thereby realizing the improvement of the motor efficiency by more than 1%.

[0068] It should be noted that other technical means can also be used to reduce the torque ripple of the motor. Referring to FIG. 5, according to some embodiments of the present application, the outer peripheral wall of the rotor core 110 is provided with a plurality of slotted openings 115, which are arranged at intervals along the circumferential direction of the rotor core 110, and the plurality of slotted openings 115 can be divided into a plurality of slot groups, and each slot group includes at least two slotted openings 115. For each slot group, there are two slotted openings 115 symmetrically arranged about the central axis X2 of the first filler 120. Along the circumferential direction of the rotor core 110, the plurality of slot groups are arranged one-to-one with the plurality of first fillers 120. Alternatively, it can be understood that along the radial direction of the rotor core 110, the plurality of slot groups are arranged one-to-one opposite to the plurality of first fillers 120. That is, for a slot group and a first filler 120, along the radial direction of the rotor core 110, the slot group is located on the outer side of the radial direction, and the first filler 120 is located on the inner side of the radial direction. In some embodiments, the shape of the slotted opening 115 can be square, which is convenient for manufacturing and processing.

[0069] In the present embodiment, by arranging a plurality of slotted openings 115 on the outer peripheral wall of the rotor core 110, the positions of the slotted openings 115 and the positions of the first fillers 120 are associated, and the plurality of slotted openings 115 are periodically distributed according to the number of the first fillers 120 (i.e. the number of poles of the motor), which can change the phase of the magnetic flux density waveform of the air gap magnetic field, reduce the high harmonic components of the magnetic flux density waveform, and further greatly reduce the torque ripple. In addition, the slotted openings 115 can also save the material of the rotor core 110, thereby reducing the cost.

[0070] Regarding the technical effects, referring to FIG. 8, a comparison diagram of torque ripples of the original scheme and the arrangement of slotted openings 115 in the embodiments of the present application is shown, and FIG. 8 depicts a graph of torque as a function of time, wherein the dashed line segment represents the function of torque as a function of time of the original scheme, and the peak of the torque is large, resulting in large fluctuations in torque and large torque ripple. The solid line segment represents the function of torque as a function of time of the embodiments of the present application, and compared with the dashed line segment, the peak of the torque is greatly reduced, the torque is relatively stable, and therefore the torque ripple is relatively stable. According to the data obtained from specific calculations, the torque ripple is reduced from 16.3% of the original scheme to 4.8% of the embodiments of the present application.

[0071] Referring to FIG. 5, according to some embodiments of the present application, the width of the slotted opening 115 in the circumferential direction of the rotor core 110 is less than or equal to 1 / 8 of the circumference of the rotor core 110, and the depth of the slotted opening 115 in the radial direction of the rotor core 110 is less than or equal to 1 / 2 of the radius of the rotor core 110. In the present embodiment, by adjusting the size of the slotted opening 115, the size of the slotted opening 115 is associated with the circumference and radius of the rotor core 110, which can further optimize the magnetic field.

[0072] According to the rotor assembly of the embodiments of the present application, in the production and manufacturing, the remanence of the first filler body or the second filler body can be increased by adjusting the magnetizing process, so that the remanence of the first filler body and the remanence of the second filler body are different. Specifically, under the working condition requirement of high load, the remanence of the second filler body can be made greater than the remanence of the first filler body, which can be understood as that the magnetic field of the second filler body is enhanced. Due to the alternate arrangement of the first filler body and the second filler body, the spatial distribution of the magnetic field can be optimized, so that the strength of the air gap magnetic field of the whole motor is enhanced, and the torque ripple is reduced, the working performance of the motor can be improved, and due to the length of the second filler body being less than the length of the first filler body, the spatial layout is optimized, the volume of the motor can be reduced, and the power density of the motor is improved. Under the working condition requirement of low load or high speed, the remanence of the second filler body can be made less than the remanence of the first filler body, which can be understood as that the magnetic field of the second filler body is weakened. Due to the alternate arrangement of the first filler body and the second filler body, the spatial distribution of the magnetic field will be changed, so that the efficiency of the motor is improved, and the speed range is widened. Overall, the remanence of the first filler body and the remanence of the second filler body are different, which can be suitable for the working condition requirements of high load, low load or high speed.

[0073] Some embodiments of the present application also provide an electric motor. Referring to FIG. 1, the electric motor includes a stator assembly 200 and the rotor assembly 100 of the above-mentioned embodiments. The stator assembly 200 includes a stator core 210, and the stator core 210 is provided with a rotor hole 211. The rotor assembly 100 is arranged in the rotor hole 211 and can rotate around a central axis X1. The rotor assembly 100 and the stator core 210 have a gap therebetween. The inner periphery of the stator core 210 is provided with a plurality of stator slots 212 arranged in the circumferential direction, and the stator slots 212 are used to install windings. The rotor core 110 is a sheet structure, which can be made of silicon steel sheets or other metal sheets with good magnetic conductivity, and has the advantage of low cost. The number of the rotor core 110 is multiple, and the multiple rotor cores 110 are arranged in a stacked manner along the central axis X1. In the direction of the central axis, the thickness of the first filler body 120 and the thickness of the second filler body 130 are both greater than the thickness of the rotor core 110. The first filler body 120 passes through the first installation slot 111 of the multiple rotor cores 110, and the second filler body 130 passes through the second installation slot 112 of the multiple rotor cores 110. In some embodiments, in the axial direction of the rotor core 110, the thickness of the first filler body 120 and the thickness of the second filler body 130 can be the same, so that the two end faces of the first filler body 120 are flush with the two end faces of the second filler body 130 in the thickness direction, facilitating the installation of the multiple rotor cores 110.

[0074] Due to the rotor assembly 100 of the above embodiment, the motor has excellent working performance, can be applied to working conditions of high load, low load or high speed, and the irreversible demagnetization resistance of the second filler 130 is enhanced, improving the reliability of the motor.

[0075] Some embodiments of the present application also provide a compressor comprising the motor of the above embodiment, which can be applied to refrigeration equipment such as air conditioners and refrigerators, so that the above refrigeration equipment has good working performance and reliability and can be applied to various different working conditions.

[0076] Of course, the present application is not limited to the above embodiments, and those skilled in the art can make equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A rotor assembly, comprising: a rotor core provided with a plurality of first installation slots and a plurality of second installation slots, the plurality of first installation slots and the plurality of second installation slots being arranged alternately along a circumferential direction of the rotor core; and a plurality of first filling bodies and a plurality of second filling bodies, the plurality of first filling bodies being respectively arranged in the plurality of first installation slots, the plurality of second filling bodies being respectively arranged in the plurality of second installation slots, along the circumferential direction of the rotor core, a length of the first filling body being greater than a length of the second filling body, the first filling body being a magnet, the second filling body being a magnet or a non-magnetic material, a residual magnetism of the first filling body being different from a residual magnetism of the second filling body. When the second filling body is a magnet, an opening is formed between the second filling body and a side wall of the second installation slot away from a central axis of the rotor core, the opening penetrating the rotor core along an axial direction of the rotor core.

2. The rotor assembly of claim 1, wherein, A projection of the rotor core along the axial direction of the rotor core includes a plurality of curve segments, along a radial direction of the rotor core, the plurality of curve segments are arranged one by one opposite to the plurality of first filling bodies, each of the plurality of curve segments is symmetrically arranged about a central axis of the first filling body.

3. The rotor assembly of claim 2, wherein, Each of the plurality of curve segments includes two first circular arc segments and two second circular arc segments, the two first circular arc segments and the two second circular arc segments are respectively symmetric about the central axis, a center of the first circular arc segment and a center of the second circular arc segment do not coincide, a radius of the first circular arc segment is greater than or equal to a radius of the second circular arc segment.

4. The rotor assembly of claim 3, wherein, The rotor core is provided with an axial hole, a radius of the axial hole is R0, a cross-sectional shape of the first filling body is a rectangle, along the circumferential direction of the rotor core, a length of the first filling body is W1, a minimum distance between the first filling body and the axial hole is H0, a number of the first filling bodies is p, and W1=2*(R0+H0)*tan(180° / p) is satisfied.

5. The rotor assembly of any one of claims 1 to 4, wherein, Cross-sectional shapes of the first filling body and the second filling body are both rectangles, along the circumferential direction of the rotor core, a length of the second filling body is W2, along the radial direction of the rotor core, a width of the first filling body is H1, a number of the first filling bodies is p, and 0<W2<2*H1*sin(180° / p) is satisfied.

6. The rotor assembly of any one of claims 3 to 5, wherein, The rotor core is provided with an axial hole, a radius of the axial hole is R0, a minimum distance between the first filling body and the axial hole is H0, each of the plurality of curve segments includes a first circular arc segment and a second circular arc segment, a radius of the first circular arc segment is greater than or equal to a radius of the second circular arc segment, the radius of the first circular arc segment is R1, along the radial direction of the rotor core, a width of the opening is H3, a minimum distance from a side wall of the opening to an outer contour line of the rotor core is H4, a width of the second filling body is H2, and 0<H2<R1-[0.5*W2 / tan(180° / p)+(R0+H0)*cos(180° / p)+H3+H4] is satisfied.

7. The rotor assembly of claim 6, wherein, ​ 8. The rotor assembly of any one of claims 1 to 7, wherein, In a cross section along a radial direction of the rotor core, a cross sectional area of the first filling body is S1, and a cross sectional area of the second filling body is S2, and 0.1≤S2 / S1≤0.3 is satisfied.

9. The rotor assembly of claim 8, wherein, The remanence of the first filler is Br1, and the remanence of the second filler is Br2, satisfying:

10. The rotor assembly of any one of claims 1 to 9, wherein, The outer peripheral wall of the rotor core is provided with a plurality of slots, and the plurality of slots are distributed along a circumferential direction of the rotor core and are divided into a plurality of slot groups. Each of the slot groups includes at least two slots. Along a radial direction of the rotor core, the plurality of slot groups are arranged opposite to the plurality of first filling bodies one by one. At least two slots in each of the slot groups are symmetrically arranged with the first filling body as a symmetric axis along an axial direction of the rotor core.

11. The rotor assembly of claim 10, wherein, A width of the slot is less than or equal to 1 / 8 of a circumference of the rotor core, and a depth of the slot is less than or equal to 1 / 2 of a radius of the rotor core.

12. An electric machine, comprising a stator assembly and the rotor assembly according to any one of claims 1 to 11, wherein the stator assembly is provided with a rotor hole, and the rotor assembly is rotatably arranged in the rotor hole.

13. A compressor, comprising a stator assembly and the rotor assembly according to any one of claims 1 to 11, wherein the stator assembly is provided with a rotor hole, and the rotor assembly is rotatably arranged in the rotor hole.

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