Rotor assembly, motor, compressor and refrigerator capable of improving resistance to demagnetization

Abstract

The present invention belongs to the technical field of drive devices and specifically discloses a rotor assembly, motor, compressor, and refrigerator capable of improving demagnetization resistance. The rotor assembly comprises: a rotor core having magnet slots disposed thereon; permanent magnets disposed within the magnet slots; and diffusion zones disposed on the plane where the width and thickness of the permanent magnets lie. The diffusion zones include: a first diffusion zone disposed on one side of the centerline of the permanent magnet's width; and / or a second diffusion zone disposed on the other side of the centerline of the permanent magnet's width. The width, thickness, length, and number of pole pairs of the permanent magnet are positively correlated with the rotor assembly's demagnetization resistance, while the distance from one end of the permanent magnet near the outer circumference of the rotor core to the rotor core's origin is negatively correlated with the rotor assembly's demagnetization resistance. The present invention derives and verifies the computational relationships between these parameters. The motor designed accordingly achieves improved local demagnetization resistance of the permanent magnets while ensuring demagnetization reliability and without increasing the size of the permanent magnets, thereby reducing the motor's production cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of drive devices, and in particular relates to a rotor assembly, a motor, a compressor and a refrigerator capable of improving resistance to demagnetization. Background Art

[0002] At present, domestic and foreign air-conditioning compressors basically use variable frequency motors, which generally use permanent magnet motors. The excitation method of the permanent magnet motor rotor is magnet excitation. Due to the high power density characteristics of permanent magnet motors and the need to reduce costs, the anti-demagnetization ability of the rotor magnet is weakened. When the magnet undergoes irreversible demagnetization, it will affect the operating performance and reliability of the motor and compressor, thereby seriously affecting the service life of the product.

[0003] At the same time, as rare earth material prices rise, the price of rare earth magnets and motor costs are skyrocketing. While ensuring reliable motor operation, reducing the costs of both magnets and motors is imperative. The fundamental reason for the rise in magnet prices is the rising price of rare earth elements. The rare earth element content affects a magnet's remanence and coercivity, with coercivity directly reflecting its resistance to demagnetization. When magnets of the same size are used in the same motor, magnets with lower coercivity have poorer rotor resistance to demagnetization, resulting in a higher risk of rotor demagnetization and more pronounced demagnetization.

[0004] Therefore, it is urgent to design a rotor assembly that can effectively solve the above-mentioned technical defects, improve the anti-demagnetization ability of the rotor assembly while ensuring demagnetization reliability and not increasing the volume of the permanent magnet, and thus improve the anti-demagnetization ability of the motor to reduce production costs. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a rotor assembly, motor, compressor and refrigerator capable of improving demagnetization resistance. By controlling the specific operational relationship between parameters such as the width, thickness, length, pole pair number of the permanent magnet in the rotor assembly and the distance between one end point of the permanent magnet close to the outer circle of the rotor core and the origin of the rotor core, the present invention can improve the local demagnetization resistance of the permanent magnet, improve the demagnetization resistance of the rotor assembly, and further improve the demagnetization resistance of the motor, thereby reducing the production cost of the motor, while ensuring demagnetization reliability and without increasing the volume of the permanent magnet.

[0006] To overcome the above technical problems, a first aspect of the present invention provides a rotor assembly.

[0007] Specifically, the rotor assembly includes:

[0008] a rotor core, wherein the rotor core is provided with magnet slots;

[0009] A permanent magnet is disposed in the magnet slot; a diffusion zone is provided on a plane where the width and thickness of the permanent magnet are located, and the diffusion zone includes:

[0010] A first diffusion region is provided on one side of the width centerline of the permanent magnet; and / or

[0011] A second diffusion region is provided on the other side of the width centerline of the permanent magnet;

[0012] Both the first diffusion region and the second diffusion region contain rare earth elements;

[0013] Among them: the width w of the permanent magnet, the thickness h of the permanent magnet, the length T of the permanent magnet, the distance O2 from the end point of the permanent magnet close to the outer circle of the rotor core to the origin of the rotor core, the maximum length L of the first diffusion zone along the width direction of the permanent magnet 1max , the maximum length W of the first diffusion region along the thickness direction of the permanent magnet 1max , and the number of pole pairs p of the permanent magnet satisfy the following formulas (1) and (2):

[0014]

[0015] In the above formula: 2.1≤k1≤25.2, 2.1≤k3≤18.3.

[0016] The rotor assembly of the present invention includes a rotor core and a permanent magnet. The rotor core includes magnet slots, and the permanent magnet is disposed in the magnet slots. Diffusion zones are provided on the plane where the width and thickness of the permanent magnet lie. The diffusion zones include a first diffusion zone and / or a second diffusion zone, wherein the first diffusion zone is provided on one side of the centerline of the width of the permanent magnet, and the second diffusion zone is provided on the other side of the centerline of the width of the permanent magnet. Both the first diffusion zone and the second diffusion zone contain rare earth elements. Because rare earth elements have excellent energy density, coercive force, and remanent magnetism, after being prepared into a slurry and applied to the surface of the permanent magnet substrate, they will penetrate and diffuse into the interior of the permanent magnet substrate to form a diffusion zone. The higher the content of rare earth elements in the slurry, the stronger the anti-demagnetization ability of the permanent magnet. At the same time, after the surface of the permanent magnet matrix is ​​coated with a slurry containing rare earth elements, it is necessary to perform high-temperature treatment (about 800-950°C, 10-18 hours) to further enhance the bonding force between the rare earth elements and the permanent magnet matrix, form a stable grain boundary state, improve the coercive force of the permanent magnet and its temperature stability, thereby improving the demagnetization resistance of the permanent magnet and, in turn, the demagnetization resistance of the motor.

[0017] Research has found that the demagnetization performance of the rotor assembly is related to the width, thickness, and length of the permanent magnets, the distance from the rotor core's outer end to the rotor core's origin, and the number of pole pairs. The width, thickness, length, and pole pair number of the permanent magnets are positively correlated with the rotor assembly's demagnetization performance. This means that as the width, thickness, length, and pole pair number of the permanent magnets increase, the demagnetization performance of the rotor assembly increases, and to achieve the same demagnetization performance, the required diffusion zone area decreases. Meanwhile, the distance from the rotor core's outer end to the rotor core's origin is negatively correlated with the rotor assembly's demagnetization performance. This means that the greater the distance from the rotor core's outer end to the rotor core's origin, the worse the rotor assembly's demagnetization performance becomes, and to achieve the same demagnetization performance, the required diffusion zone area increases. Furthermore, the area of ​​the diffusion zone is related to the maximum length of each diffusion zone along the permanent magnet's thickness and width. Therefore, by reasonably setting the width w of the permanent magnet, the thickness h of the permanent magnet, the length T of the permanent magnet, the distance O2 from the end point of the permanent magnet close to the outer circle of the rotor core to the origin of the rotor core, the maximum length L of the first diffusion zone along the width direction of the permanent magnet, 1max , the maximum length W of the first diffusion region along the thickness direction of the permanent magnet 1max and the number of pole pairs p of the permanent magnet, and making them satisfy the operational relationships of the above formulas (1) and (2). This can improve the local anti-demagnetization ability of the permanent magnet and the anti-demagnetization ability of the rotor assembly, thereby improving the anti-demagnetization ability of the motor and reducing the production cost of the motor while ensuring the demagnetization reliability and not increasing the volume of the permanent magnet.

[0018] Preferably, in formula (1) and formula (2), 4.0≤k1≤5.9, 3.4≤k3≤5.1.

[0019] As a further improvement of the above technical solution, the maximum length L of the second diffusion region along the width direction of the permanent magnet is 2max , the maximum length W of the second diffusion region along the thickness direction of the permanent magnet 2max The following formulas (3) and (4) are satisfied:

[0020]

[0021] In the above formula: 2.1≤k2≤25.2, 2.1≤k4≤18.3.

[0022] Specifically, when the maximum length of the second diffusion zone along the width and thickness directions of the permanent magnet satisfies formulas (3) and (4), the first diffusion zone can be supplemented, thereby further improving the local anti-demagnetization capability of the permanent magnet while ensuring demagnetization reliability and without increasing the volume of the permanent magnet.

[0023] Preferably, in formula (3) and formula (4), 4.0≤k1≤5.9, 3.4≤k3≤5.1.

[0024] As a further improvement of the above technical solution, the rare earth element includes at least one of dysprosium, terbium, praseodymium, neodymium, and cerium.

[0025] Specifically, these rare earth elements penetrate and diffuse into the permanent magnet. During the high-temperature treatment process, they can form intermetallic compounds with the transition metal elements in the permanent magnet. The strong exchange interaction between the transition metal elements makes the compounds have a higher Curie temperature. The transition metal atoms have a larger magnetic moment, which ensures that the compounds have a higher saturation magnetization intensity. The localized 4f electrons of the rare earth elements can provide strong anisotropy. The combined effect of the two types of elements is conducive to improving the coercive force of the permanent magnet, thereby enhancing the permanent magnet's anti-demagnetization ability, and further improving the motor's anti-demagnetization ability.

[0026] Preferably, the rare earth element includes at least one of dysprosium, terbium and neodymium.

[0027] As a further improvement of the above technical solution, the rare earth elements are uniformly distributed or non-uniformly distributed in the diffusion zone.

[0028] Specifically, the distribution of rare earth elements in the permanent magnet refers to the distribution of rare earth elements in the diffusion region. The rare earth elements in the diffusion region may be evenly distributed or unevenly distributed, which mainly depends on the diffusion process.

[0029] As a further improvement of the above technical solution, the content of the rare earth element in the first diffusion region accounts for a mass percentage g1 of the permanent magnet of 0.99%-2.2%.

[0030] Specifically, the low-cost requirements of the motor are met by controlling the mass percentage of rare earth elements in the first diffusion region. The mass percentage of rare earth elements in the first diffusion region must be greater than 0.99% to ensure that the first diffusion region meets the minimum requirement for the coercive force of the permanent magnet, thereby ensuring that the first diffusion region can enhance the demagnetization resistance of the entire permanent magnet. Furthermore, the mass percentage of rare earth elements in the first diffusion region must be less than 2.2%. This ensures that the first diffusion region has strong demagnetization resistance while reducing the cost of the permanent magnet, thereby meeting the low-cost requirements of the motor.

[0031] As a further improvement of the above technical solution, the content of the rare earth element in the second diffusion region accounts for a mass percentage g2 of the permanent magnet of 0.99%-2.2%.

[0032] Specifically, the mass percentage of rare earth elements in the second diffusion zone is the same as that in the first diffusion zone, allowing it to supplement the first diffusion zone or function independently. Furthermore, the mass percentage of rare earth elements in the second diffusion zone must be greater than 0.99% to ensure that the second diffusion zone meets the minimum coercivity requirement for the permanent magnet, thereby enhancing the overall demagnetization resistance of the permanent magnet. Furthermore, the mass percentage of rare earth elements in the second diffusion zone must be less than 2.2%, which reduces the cost of the permanent magnet while ensuring strong demagnetization resistance in the second diffusion zone, thereby meeting the low-cost requirements of the motor.

[0033] As a further improvement of the above technical solution, the permanent magnet further includes a non-diffusion zone, the content of rare earth elements in the non-diffusion zone accounts for a mass percentage of g3 of the permanent magnet, and g3 <g1,g3<g2。

[0034] Specifically, the non-diffusion zone refers to the area of ​​the permanent magnet where the rare earth element-containing slurry has not penetrated or diffused, that is, the area where 3D diffusion technology is not used. The mass proportion of rare earth elements in the non-diffusion zone is less than the mass proportion of rare earth elements in the first and second diffusion zones, that is, the coercive force of both diffusion zones is greater than that of the non-diffusion zone. Therefore, the coercive magnetic field strength that the first and second diffusion zones can withstand is greater than the coercive magnetic field strength that the non-diffusion zone can withstand. Therefore, when the non-diffusion zone faces the risk of demagnetization, its own magnetic induction strength can be maintained, thereby preventing irreversible demagnetization in the non-diffusion zone, thereby improving the permanent magnet's anti-demagnetization capability, extending the permanent magnet's service life, and improving its reliability.

[0035] As a further improvement of the above technical solution, the permanent magnet further includes a plurality of third diffusion zones, the third diffusion zones being arranged between the first diffusion zone and the second diffusion zone, and the weight of the rare earth element in each of the third diffusion zones accounts for a percentage of the weight of the permanent magnet of g. i , g i >g3.

[0036] Specifically, in addition to the first and / or second diffusion regions, the permanent magnet may also include several third diffusion regions, which can serve as supplements to the first and second diffusion regions, and are disposed between the first and second diffusion regions. Furthermore, the mass fraction of rare earth elements in each diffusion region is greater than that in the non-diffusion region, meaning that the coercive force of the third diffusion region is greater than that of the non-diffusion region. By providing third and non-diffusion regions with different mass fractions, each permanent magnet can be formed with third and non-diffusion regions having different demagnetization capabilities. This enhances the permanent magnet's anti-demagnetization properties through the gradient anti-demagnetization region, thereby reducing the risk of irreversible demagnetization.

[0037] Preferably, the permanent magnet includes the first diffusion region, the second diffusion region and the third diffusion region, and the third diffusion region is arranged between the first diffusion region and the second diffusion region, and the first diffusion region, the second diffusion region and the third diffusion region form a circular shape.

[0038] Preferably, the permanent magnet includes the first diffusion region and the second diffusion region, and the first diffusion region and the second diffusion region are respectively arranged at four corners of the permanent magnet.

[0039] Preferably, the permanent magnet includes the first diffusion region, the second diffusion region and the third diffusion region, and the first diffusion region, the second diffusion region and the third diffusion region are respectively arranged in parallel on both sides and the middle of the permanent magnet in a three-strip shape.

[0040] Specifically, the first, second, and third diffusion regions can be incorporated into the permanent magnet simultaneously or separately. In a permanent magnet motor, the permanent magnet is susceptible to demagnetization at its ends and in the middle of its width, along the plane of its width and thickness. Furthermore, the permanent magnet is also susceptible to demagnetization at its ends along its length. Therefore, placing diffusion regions in locations prone to demagnetization can improve demagnetization resistance while reducing costs.

[0041] As a further improvement of the above technical solution, the value ranges of the parameters in formula (1) and formula (2) arbitrarily satisfy one or more of the following: 1mm≤w≤20mm; 1mm≤h≤4mm; 20mm≤T≤80mm; 15mm≤O2≤40mm; 1mm≤L 1max ≤20mm; 1mm≤W 1max ≤4mm;P≥2.

[0042] Preferably, the value ranges of the parameters in formula (1) and formula (2) satisfy any one or more of the following:

[0043] 9.2mm≤w≤13.8mm; 1.5mm≤h≤2.3mm; 32mm≤T≤48mm; 22.6mm≤O2≤33.8mm; 2.8mm≤L 1max ≤4.2mm; 1.5mm≤W 1max ≤2.3mm;P=3.

[0044] As a further improvement of the above technical solution, the value ranges of the parameters in formula (3) and formula (4) arbitrarily satisfy one or more of the following: 1mm≤w≤20mm; 1mm≤h≤4mm; 20mm≤T≤80mm; 15mm≤O2≤40mm; 1mm≤L 2max ≤20mm; 1mm≤W 2max≤4mm;P≥2.

[0045] Preferably, the value ranges of the parameters in formula (3) and formula (4) satisfy any one or more of the following: 9.2mm≤w≤13.8mm; 1.5mm≤h≤2.3mm; 32mm≤T≤48mm; 22.6mm≤O2≤33.8mm; 2.8mm≤L 2max ≤4.2mm; 1.5mm≤W 2max ≤2.3mm;P=3.

[0046] Specifically, by defining the parameters in the formula: the width w of the permanent magnet, the thickness h of the permanent magnet, the length T of the permanent magnet, the distance O2 from the end point of the permanent magnet close to the outer circle of the rotor core to the origin of the rotor core, the maximum length L of the first diffusion zone along the width direction of the permanent magnet, 1max , the maximum length W of the first diffusion region along the thickness direction of the permanent magnet 1max , the maximum length L of the second diffusion region along the width direction of the permanent magnet 2max , the maximum length W of the second diffusion region along the thickness direction of the permanent magnet 2max and the range of the pole pair number p of the permanent magnet so that it satisfies 2.1≤k1≤25.2, 2.1≤k2≤25.2, 2.1≤k3≤18.3, and 2.1≤k4≤18.3 in each formula, thereby improving the local anti-demagnetization ability of the permanent magnet and the anti-demagnetization ability of the rotor assembly while ensuring demagnetization reliability and not increasing the volume of the permanent magnet, thereby improving the anti-demagnetization ability of the motor and reducing the production cost of the motor.

[0047] As a further improvement of the above technical solution, the first diffusion region and the second diffusion region are distributed over the entire area or partially along the axial direction of the permanent magnet.

[0048] Specifically, the first diffusion zone and the second diffusion zone can be distributed in the entire area or partially along the axial direction of the permanent magnet, which means: the distribution of the first diffusion zone and the second diffusion zone along the length direction of the permanent magnet can be distributed in the entire area or in a partial area, which mainly depends on the requirements of the permanent magnet for anti-demagnetization performance. The partial area distribution is mainly to reduce the diffusion area, thereby reducing costs.

[0049] As a further improvement of the above technical solution, the rotor assembly includes a plurality of permanent magnets, and the diffusion areas on cross sections of the permanent magnets having different widths and thicknesses are the same or different.

[0050] Specifically, by installing multiple permanent magnets on the rotor assembly, the rotor assembly's resistance to demagnetization can be enhanced, further reducing the likelihood of irreversible demagnetization. For a single permanent magnet, the diffusion zones can be the same or different across the width and thickness planes along different lengths of the permanent magnet, as long as the overall resistance to demagnetization is maintained.

[0051] As a further improvement of the above technical solution, the permanent magnet is magnetized radially or parallelly.

[0052] Specifically, the permanent magnets can be magnetized in either a radial or parallel direction. It is essential that the magnetization direction of each permanent magnet on the rotor assembly is consistent, and that the magnetization directions of the first, second, third, and non-diffusion regions within each permanent magnet are consistent. If the non-diffusion region demagnetizes due to an external magnetic field, the first, second, and third diffusion regions, which have stronger demagnetization resistance, can maintain their own magnetism. Thus, the non-diffusion region is magnetized by the first, second, and third diffusion regions, thereby preventing irreversible demagnetization of the permanent magnets.

[0053] As a further improvement of the above technical solution, the rotor core is formed by stacking multiple silicon steel sheets.

[0054] Specifically, the rotor core is constructed from multiple laminated silicon steel sheets. This lamination process helps reduce eddy current losses. During operation, the rotor core is exposed to a changing magnetic field, and the resulting currents within it lead to energy losses known as eddy current losses. This stacking of silicon steel sheets effectively reduces iron losses and improves the reliability of the rotor assembly.

[0055] A second aspect of the present invention provides an electric motor.

[0056] Specifically, a motor includes:

[0057] A rotor assembly as described in any technical solution of the first aspect of the present invention.

[0058] The motor provided by the present invention comprises a stator assembly and a rotor assembly according to any of the technical solutions of the first aspect described above, wherein: the stator assembly comprises a stator core and a winding; the stator core is provided with a protrusion for fixing the winding; the winding is formed by a coil wrapped around the protrusion; the stator core is disposed around the outer side of the rotor core, forming a gap. Because the motor includes the rotor assembly according to any of the technical solutions described above, it has all the beneficial effects achievable by the rotor assembly. To avoid repetition, this description is not repeated here.

[0059] A third aspect of the present invention provides a compressor.

[0060] Specifically, a compressor includes:

[0061] The rotor assembly as described in any technical solution of the first aspect of the present invention; or

[0062] The motor as described in the second aspect of the present invention.

[0063] The compressor provided by the present invention includes the rotor assembly described in any of the technical solutions of the first aspect or the motor described in any of the technical solutions of the second aspect. Because the compressor includes the rotor assembly or motor of any of the technical solutions described above, it has all the beneficial effects achieved by the rotor assembly or motor. To avoid repetition, these are not further described here.

[0064] A fourth aspect of the present invention provides a refrigerator.

[0065] Specifically, a refrigerator includes:

[0066] The motor according to the second aspect of the present invention; or

[0067] A compressor as described in the third aspect of the present invention.

[0068] The refrigerator provided by the present invention includes the motor described in the second aspect or the compressor described in the third aspect. Since the refrigerator includes the motor or compressor of the above technical solution, it has all the beneficial effects that can be achieved by the motor or compressor. To avoid repetition, they are not described here.

[0069] Compared with the prior art, the above technical solution of the present invention has at least the following technical effects or advantages:

[0070] (1) The present invention is based on the fact that the width, thickness, length and pole pair number of the permanent magnet are positively correlated with the anti-demagnetization performance of the rotor assembly, and the distance between the end point of the permanent magnet close to the outer circle of the rotor core and the origin of the rotor core is negatively correlated with the anti-demagnetization performance of the rotor assembly. It is deduced and verified that by reasonably setting the width w of the permanent magnet, the thickness h of the permanent magnet, the length T of the permanent magnet, the distance O2 between the end point of the permanent magnet close to the outer circle of the rotor core and the origin of the rotor core, and the maximum length L of the first diffusion zone along the width direction of the permanent magnet 1max , the maximum length W of the first diffusion region along the thickness direction of the permanent magnet 1max and the number of pole pairs p of the permanent magnet, and satisfying the above formulas (1) and (2), it is possible to improve the local anti-demagnetization ability of the permanent magnet while ensuring the demagnetization reliability and without increasing the volume of the permanent magnet, thereby improving the anti-demagnetization ability of the rotor assembly, further improving the anti-demagnetization ability of the motor, and reducing the production cost of the motor.

[0071] (2) The rotor assembly provided by the present invention has a permanent magnet whose demagnetization rate at 50A / 130°C can reach 2.65%. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic structural diagram of a rotor assembly according to an embodiment of the present invention;

[0073] Figure 2 Schematic diagram of the dimensions of the rotor assembly according to an embodiment of the present invention Figure 1 ;

[0074] Figure 3 Schematic diagram of the dimensions of the rotor assembly according to an embodiment of the present invention Figure 2 ;

[0075] Figure 4 A schematic diagram of the structure and orientation of a V-shaped rotor assembly according to an embodiment of the present invention;

[0076] Figure 5 This is a schematic structural diagram of a permanent magnet diffusion zone in a rotor assembly according to an embodiment of the present invention;

[0077] Figure 6 This is a schematic structural diagram of a U-shaped diffusion zone of a permanent magnet according to an embodiment of the present invention;

[0078] Figure 7 This is a schematic structural diagram of a quadrangular diffusion region of a permanent magnet according to an embodiment of the present invention;

[0079] Figure 8 This is a schematic structural diagram of three-strip diffusion regions of a permanent magnet according to an embodiment of the present invention;

[0080] Figure 9 This is a schematic structural diagram of a single diffusion zone of a permanent magnet according to an embodiment of the present invention;

[0081] Figure 10 The figure is a schematic structural diagram of a motor according to an embodiment of the present invention.

[0082] In the accompanying drawings: 100-motor, 110-rotor assembly, 111-rotor core, 112-permanent magnet, 1111-magnet slot, 120-stator assembly, 121-stator core, 122-winding, 1211-protrusion, 1121-diffusion region, 11211-first diffusion region, 11212-second diffusion region, 11213-third diffusion region, 11214-non-diffusion region. DETAILED DESCRIPTION

[0083] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments to facilitate understanding of the present invention by those skilled in the art. It is necessary to point out that the embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned invention contents shall still fall within the scope of protection of the present invention.

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

[0085] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0086] Refer to the following Figure 1-10 A rotor assembly, a motor, and a compressor according to some embodiments of the present invention are described.

[0087] Example 1

[0088] like Figure 1 and 4 As shown, according to a first aspect of the present invention, an embodiment provides a rotor assembly 110, comprising a rotor core 111 and permanent magnets 112. The rotor core 111 is provided with magnet slots 1111, and the permanent magnets 112 are installed in the magnet slots 1111. A diffusion region 1121 is provided on a plane corresponding to the width and thickness of the permanent magnets 112. The diffusion region 1121 may include only a first diffusion region 11211 or a second diffusion region 11212, or may include both the first diffusion region 11211 and the second diffusion region 11212. The first diffusion region 11211 is provided on one side of the width centerline of the permanent magnet 112, and the second diffusion region 11212 is provided on the other side of the width centerline of the permanent magnet 112.

[0089] The first diffusion zone 11211 and the second diffusion zone 11212 are formed by coating a layer of slurry containing rare earth elements on the surface of the permanent magnet 112 substrate during the manufacturing process of the permanent magnet 112 to enhance the demagnetization resistance of the permanent magnet 112. To meet different antimagnetic performance requirements, the slurry containing rare earth elements can be coated on one side of the width centerline of the permanent magnet 112 to form the first diffusion zone 11211; the slurry containing rare earth elements can be coated on the other side of the width centerline of the permanent magnet 112 to form the second diffusion zone 11212; or the slurry containing rare earth elements can be coated on both sides of the width centerline of the permanent magnet 112 to form the first diffusion zone 11211 and the second diffusion zone 11212. Furthermore, the rare earth content in the slurry can be controlled to meet different anti-demagnetization performance requirements.

[0090] Furthermore, both the first diffusion zone 11211 and the second diffusion zone 11212 contain rare earth elements. Since rare earth elements have excellent energy density, coercive force and residual magnetism properties, after being prepared into a slurry and coated on the surface of the permanent magnet 112 matrix, they will penetrate and diffuse into the interior of the permanent magnet 112 matrix to form a diffusion zone 1121, thereby improving the anti-demagnetization ability of the permanent magnet 112, and thereby improving the anti-demagnetization ability of the motor.

[0091] like Figure 2-3 As shown, the demagnetization performance of the rotor assembly 110 is positively correlated with the width, thickness, length, distance between the end point of the permanent magnet 112 close to the outer circumference of the rotor core 111 and the origin of the rotor core 111, and the number of pole pairs of the permanent magnet 112. The distance between the end point of the permanent magnet 112 close to the outer circumference of the rotor core 111 and the origin of the rotor core 111 is negatively correlated with the demagnetization performance of the rotor assembly 110. That is, as the width, thickness, length, and pole pair number of the permanent magnet 112 increase, the demagnetization performance of the rotor assembly 110 also increases. To achieve the same demagnetization performance, the area of ​​the diffusion region 1121 needs to decrease. At the same time, the greater the distance between the end point of the permanent magnet 112 close to the outer circumference of the rotor core 111 and the origin of the rotor core 111, the worse the demagnetization performance of the rotor assembly 110 is. To achieve the same demagnetization performance, the area of ​​the diffusion region 1121 needs to increase. In addition, the area of ​​the diffusion region 1121 is determined by the maximum length of each diffusion region 1121 along the thickness direction and the width direction of the permanent magnet 112 .

[0092] Therefore, by reasonably setting the relationship between the various parameters, specifically, the width of the permanent magnet 112 is w, the thickness of the permanent magnet 112 is h, the length of the permanent magnet 112 is T, the distance between the end point of the permanent magnet 112 close to the outer circle of the rotor core 111 and the origin of the rotor core 111 is O2, and the maximum length of the first diffusion region 11211 along the width direction of the permanent magnet 112 is L. 1maxThe maximum length of the first diffusion region 11211 along the thickness direction of the permanent magnet 112 is W 1max The maximum length of the second diffusion region 11212 along the width direction of the permanent magnet 112 is L 2max The maximum length of the second diffusion region 11212 along the thickness direction of the permanent magnet 112 is W 2max The number of pole pairs of the permanent magnet 112 is p, and the above parameters satisfy the calculation relationship of the following formula (1)-(2) or formula (1)-(4). Under the premise of ensuring the demagnetization reliability and not increasing the volume of the permanent magnet 112, the local anti-demagnetization ability of the permanent magnet 112 can be improved, the anti-demagnetization ability of the rotor assembly 110 can be improved, and the anti-demagnetization ability of the motor can be improved, thereby reducing the production cost of the motor.

[0093]

[0094]

[0095] In the above formula: 2.1≤k1≤25.2, 2.1≤k2≤25.2, 2.1≤k3≤18.3, 2.1≤k4≤18.3.

[0096] like Figure 4 As shown, further, the magnet slots 1111 are V-shaped, and the V-shaped distribution of the permanent magnets 112 is beneficial to further enhance the anti-demagnetization capability of the rotor assembly 110 .

[0097] Example 2

[0098] like Figure 1 As shown, in one embodiment of the present invention, based on the above-mentioned embodiment 1, the rare earth elements further include at least one of dysprosium, terbium, praseodymium, neodymium, and cerium, and the rare earth elements are uniformly or non-uniformly distributed in the permanent magnet 112. These rare earth elements penetrate and diffuse into the permanent magnet 112. During the high-temperature treatment process, they can form intermetallic compounds with the transition metal elements in the permanent magnet 112. The strong exchange interaction between the transition metal elements makes the compound have a higher Curie temperature. The large magnetic moment of the transition metal atoms ensures that the compound has a high saturation magnetization intensity. The localized 4f electrons of the rare earth elements can provide strong anisotropy. The combined effect of the two types of elements is conducive to improving the coercive force of the permanent magnet 112, thereby enhancing the anti-demagnetization ability of the permanent magnet 112, and further improving the anti-demagnetization ability of the motor.

[0099] The distribution of rare earth elements in the permanent magnet 112 refers to the distribution of rare earth elements in the diffusion region. The rare earth elements in the diffusion region can be evenly distributed or unevenly distributed, depending mainly on the diffusion process and the requirements for the demagnetization resistance of the permanent magnet 112. When the demagnetization resistance requirements of the permanent magnet 112 are high, a slurry with a high rare earth element content needs to be coated on the permanent magnet 112. In this case, the slurry has a high concentration and poor permeability and diffusion, which easily leads to uneven distribution of rare earth elements, thereby forming diffusion regions with relatively stronger demagnetization resistance in some regions, thereby improving the overall demagnetization resistance of the motor 100. When the demagnetization resistance requirements of the permanent magnet 112 are low, a slurry with a low rare earth element content can be coated on the permanent magnet 112. In this case, the slurry has a low concentration and good permeability and diffusion, which easily leads to even distribution of rare earth elements, thereby forming a balanced demagnetization resistance region in the diffusion region, which can also effectively improve the overall demagnetization resistance of the motor 100.

[0100] Example 3

[0101] like Figure 1 As shown, in one embodiment of the present invention, based on the above embodiment 1 or 2, the mass percentage g1 of the rare earth element in the first diffusion region 11211 in the permanent magnet 112 is further controlled to be 0.99%-2.2%.

[0102] In this embodiment, the low-cost requirement of the motor is met by controlling the weight percentage range of the rare earth elements in the first diffusion region 11211. The mass percentage of the rare earth elements in the first diffusion region 11211 must be greater than 0.99% to ensure that the first diffusion region 11211 has the minimum coercivity requirement for the permanent magnet 112, thereby ensuring that the first diffusion region 11211 can enhance the demagnetization resistance of the entire permanent magnet 112. At the same time, the mass percentage of the rare earth elements in the first diffusion region 11211 is limited to less than 2.2%. This can reduce the cost of the permanent magnet 112 while ensuring that the first diffusion region 11211 has strong demagnetization resistance, thereby meeting the low-cost requirement of the motor.

[0103] Further, the mass percentage g2 of rare earth elements in the second diffusion region 11212 in the permanent magnet 112 is controlled to be 0.99% - 2.2%. The weight ratio of rare earth elements in the second diffusion region 11212 is the same as that in the first diffusion region 11211, which can be used as a supplement to the first diffusion region 11211 or independently as a diffusion region. At the same time, the mass percentage of rare earth elements in the second diffusion region 11212 needs to be greater than 0.99% to ensure that the second diffusion region 11212 meets the minimum requirements for the coercivity of the permanent magnet 112, thereby ensuring that the second diffusion region 11212 can improve the demagnetization resistance of the entire permanent magnet 112. At the same time, it is specified that the mass percentage of rare earth elements in the second diffusion region 11212 needs to be less than 2.2%, which can reduce the cost of the permanent magnet 112 while ensuring that the second diffusion region 11212 has strong demagnetization resistance, so as to meet the low-cost requirements of the motor.

[0104] Further, the permanent magnet 112 may further include a non-diffusion region 11214, and the mass percentage of rare earth elements in the non-diffusion region 11214 in the permanent magnet 112 is controlled to be g3, and g3 < g1, g3 < g2. The non-diffusion region 11214 refers to the region in the permanent magnet 112 where the slurry containing rare earth elements has not penetrated or diffused. The weight ratio of rare earth elements in the non-diffusion region 一 11214 is less than that in the first diffusion region 11211 and the second diffusion region 11212, that is, the coercivities of the two diffusion regions are both greater than that of the non-diffusion region 11214. Therefore, the intensity of the coercive magnetic field that the first diffusion region 11211 and the second diffusion region 11212 can resist is greater than that of the non-diffusion region 11214. Thus, when the non-diffusion region 11214 faces the risk of demagnetization, it can maintain its magnetic induction intensity, and then prevent the non-diffusion region 11214 from undergoing irreversible demagnetization, so as to improve the demagnetization resistance of the permanent magnet 112, extend the service life of the permanent magnet 112, and improve its reliability.

[0105] As Figure 5 shown, further, the permanent magnet 112 may further include several third diffusion regions 11213, and the percentage g of the weight of rare earth elements in each third diffusion region 11213 in the weight of the permanent magnet 112 i>g3. In addition to the first diffusion region 11211 and / or the second diffusion region 11212, the permanent magnet 112 may also include a plurality of third diffusion regions 11213 to supplement the first diffusion region 11211 and the second diffusion region 11212. Furthermore, the mass fraction of rare earth elements in each diffusion region is greater than that of the non-diffusion region 11214, i.e., the coercive force of the third diffusion region 11213 is greater than that of the non-diffusion region 11214. By providing third diffusion regions 11213 and non-diffusion regions 11214 with different mass fractions, third diffusion regions 11213 and non-diffusion regions 11214 with different demagnetization capabilities can be formed on each permanent magnet 112. This enhances the anti-demagnetization performance of the permanent magnet 112 through the gradient anti-demagnetization region, thereby reducing the occurrence of irreversible demagnetization in the permanent magnet 112.

[0106] like Figure 6-9 As shown, the first diffusion region 11211, the second diffusion region 11212, and the third diffusion region 11213 can be simultaneously disposed within the permanent magnet 112, or individually disposed within the permanent magnet 112. For a permanent magnet motor, in the plane of the width and thickness of the permanent magnet 112, the permanent magnet 112 is susceptible to demagnetization at both ends of the width and in the middle of the width. Furthermore, the permanent magnet 112 is also susceptible to demagnetization at both ends of the length. Therefore, disposing diffusion regions at locations where the permanent magnet 112 is susceptible to demagnetization can both improve demagnetization resistance and reduce costs.

[0107] like Figure 6 As shown, the permanent magnet 112 includes a first diffusion region 11211, a second diffusion region 11212 and a third diffusion region 11213, and the third diffusion region 11213 is arranged between the first diffusion region 11211 and the second diffusion region 11212. The first diffusion region 11211, the second diffusion region 11212 and the third diffusion region 11213 form a circular shape.

[0108] like Figure 7 As shown, the permanent magnet 112 includes a first diffusion region 11211 and a second diffusion region 11212 , and the first diffusion region 11211 and the second diffusion region 11212 are respectively disposed at four corners of the permanent magnet 112 .

[0109] like Figure 8 As shown, the permanent magnet 112 includes a first diffusion region 11211, a second diffusion region 11212 and a third diffusion region 11213, and the first diffusion region 11211, the second diffusion region 11212 and the third diffusion region 11213 are respectively arranged in parallel on both sides and the middle of the permanent magnet 112, forming a three-strip shape.

[0110] like Figure 9 As shown, the permanent magnet 112 only includes the second diffusion region 11212 .

[0111] Example 4

[0112] like Figure 1-3 As shown, in one embodiment of the present invention, based on any one of the above embodiments 1 to 3, further, the value range of each parameter in each calculation formula satisfies any one or more of the following: 1mm≤w≤20mm; 1mm≤h≤4mm; 20mm≤T≤80mm; 15mm≤O2≤40mm; 1mm≤L 1max ≤20mm; 1mm≤L 2max ≤20mm; 1mm≤W 1max ≤4mm; 1mm≤W 2max ≤4mm;P≥2.

[0113] In this embodiment, by defining the parameters in the formula as follows: the width of the permanent magnet 112 is w, the thickness of the permanent magnet 112 is h, the length of the permanent magnet 112 is T, the distance from one end point of the permanent magnet 112 close to the outer circle of the rotor core 111 to the origin of the rotor core 111 is O2, and the maximum length L of the first diffusion region 11211 along the width direction of the permanent magnet 112 1max The maximum length of the first diffusion region 11211 along the thickness direction of the permanent magnet 112 is W 1max The maximum length of the second diffusion region 11212 along the width direction of the permanent magnet 112 is L 2max The maximum length of the second diffusion region 11212 along the thickness direction of the permanent magnet 112 is W 2max The range value of the number of pole pairs of the permanent magnet 112 is p, so that it satisfies 2.1≤k1≤25.2; 2.1≤k2≤25.2; 2.1≤k3≤18.3; 2.1≤k4≤18.3 in each formula, thereby improving the local anti-demagnetization ability of the permanent magnet 112 and the anti-demagnetization ability of the rotor assembly 110 while ensuring the demagnetization reliability and not increasing the volume of the permanent magnet 112, thereby improving the anti-demagnetization ability of the motor and reducing the production cost of the motor.

[0114] Example 5

[0115] like Figure 1 As shown, in one embodiment of the present invention, based on any one of the above embodiments 1 to 4, further, the first diffusion region 11211 and the second diffusion region 11212 are distributed in the entire area or partially along the axial direction of the permanent magnet 112.

[0116] In this embodiment, the first diffusion zone 11211 and the second diffusion zone 11212 can be distributed in the entire area along the axial direction of the permanent magnet 112, or they can be distributed partially. Specifically, it refers to: the distribution of the first diffusion zone 11211 and the second diffusion zone 11212 along the length direction of the permanent magnet 112. The distribution along the length direction can be distributed in the entire area or in a partial area, which mainly depends on the requirements of the permanent magnet 112 for anti-demagnetization performance. The partial area distribution is mainly to reduce the diffusion area, thereby reducing costs.

[0117] Furthermore, the rotor assembly 110 includes multiple permanent magnets 112. The diffusion regions 1121 of the permanent magnets 112 may be the same or different across the cross-sections of their width and thickness. By providing multiple permanent magnets 112 on the rotor assembly 110, the rotor assembly 110's resistance to demagnetization can be enhanced, further reducing the likelihood of irreversible demagnetization of the rotor assembly 110. Furthermore, for a single permanent magnet 112, the diffusion regions 1121 may be the same or different across the width and thickness planes along the length of the permanent magnet 112, as long as the overall resistance to demagnetization of the permanent magnet 112 is maintained.

[0118] Furthermore, the permanent magnet 112 is magnetized radially or in parallel. The magnetization direction of the permanent magnet 112 can be radial or parallel, as long as the magnetization direction of each permanent magnet 112 on the rotor assembly 110 is consistent, and the magnetization directions of the first diffusion region 11211, the second diffusion region 11212, the third diffusion region 11213, and the non-diffusion region 11214 in each permanent magnet 112 are consistent. When the non-diffusion region 11214 is demagnetized by an external magnetic field, the first diffusion region 11211, the second diffusion region 11212, and the third diffusion region 11213, which have stronger demagnetization resistance, can maintain their own magnetism. Thus, the non-diffusion region 11214 is magnetized by the first diffusion region 11211, the second diffusion region 11212, and the third diffusion region 11213, thereby preventing irreversible demagnetization of the permanent magnet 112.

[0119] Furthermore, the rotor core 111 is formed by stacking multiple silicon steel sheets. The rotor core 111 is formed by stacking multiple silicon steel sheets. Processing the rotor core 111 in a stacked manner helps reduce eddy current losses. When the rotor core 111 is operating, it is in a changing magnetic field. The current induced within it will result in energy loss, which is called eddy current loss. The rotor core 111 is formed by stacking silicon steel sheets, which can effectively reduce iron loss and improve the reliability of the rotor assembly 110.

[0120] Example 6

[0121] like Figure 10According to a second aspect of the present invention, an embodiment provides a motor 100 comprising a stator assembly 120 and a rotor assembly 110 according to any of the technical solutions of the first aspect. Stator assembly 120 comprises a stator core 121 and a winding 122. Stator core 121 is provided with a protrusion 1211 for securing winding 122. Winding 122 is formed by coils wrapped around protrusion 1211. Stator core 121 surrounds rotor core 111, forming a gap therebetween. Since motor 100 includes rotor assembly 110 according to any of the technical solutions described above, it achieves all the beneficial effects achievable by rotor assembly 110.

[0122] Example 7

[0123] like Figure 10 As shown, according to the third aspect of the present invention, an embodiment proposes a compressor, including a rotor assembly 110 of any technical solution of the first aspect or a motor 100 of any technical solution of the second aspect. Since the compressor includes the rotor assembly 110 or the motor 100 of any technical solution, it has all the beneficial effects that can be achieved by the rotor assembly 110 or the motor 100.

[0124] Example 8

[0125] like Figure 10 As shown, according to the fourth aspect of the present invention, an embodiment proposes a refrigerator, including the motor 100 of any technical solution of the second aspect or the compressor of any technical solution of the third aspect. Since the refrigerator includes the motor 100 or the compressor of any technical solution, it has all the beneficial effects that can be achieved by the motor 100 or the compressor.

[0126] Furthermore, the refrigerator further comprises a pipeline, the pipeline being connected to the compressor, and the refrigerant circulates through the pipeline and the compression mechanism to achieve heat exchange and refrigeration. Specifically, the refrigerator is an air conditioner.

[0127] The following describes specific applications of rotor assemblies of some embodiments of the present invention and comparative examples based on the rotor assemblies of embodiments 1-5 above.

[0128] Application Example 1

[0129] A rotor assembly 110 includes a rotor core 111 and permanent magnets 112. The rotor core 111 is provided with magnet slots 1111, within which the permanent magnets 112 are mounted. Diffusion regions 1121 are provided on the plane corresponding to the width and thickness of the permanent magnets 112. Diffusion regions 1121 include a first diffusion region 11211 and a second diffusion region 11212. The first diffusion region 11211 is located on one side of the width centerline of the permanent magnets 112, while the second diffusion region 11212 is located on the other side of the width centerline of the permanent magnets 112. The rotor core 111 is constructed from a plurality of stacked silicon steel sheets, and the permanent magnets 112 are radially magnetized.

[0130] A permanent magnet with dimensions and grades of 1.9×13×40 / 42SH was selected. A slurry containing the rare earth element neodymium was applied to both ends of the magnet along its length and subjected to high-temperature treatment. This formed a first diffusion region 11211 and a second diffusion region 11212, which were evenly distributed along the entire axial direction of the permanent magnet 112, resulting in the permanent magnet 112 of this application example. The rare earth element neodymium accounted for 1.5% by weight in the first diffusion region 11211, and 1.5% by weight in the second diffusion region 11212. The non-diffusion region contained no rare earth element neodymium.

[0131] The width w of the permanent magnet 112 is 11.5 mm, the thickness h of the permanent magnet 112 is 1.9 mm, the length T of the permanent magnet 112 is 40 mm, the distance O2 from the end point of the permanent magnet 112 close to the outer circle of the rotor core 111 to the origin of the rotor core 111 is 28.2 mm, and the maximum length L of the first diffusion region 11211 along the width direction of the permanent magnet 112 is 11.5 mm. 1max The maximum length W of the first diffusion region 11211 along the thickness direction of the permanent magnet 112 is 3.5 mm. 1max The maximum length L of the second diffusion region 11212 along the width direction of the permanent magnet 112 is 1.9 mm. 2max The maximum length W of the second diffusion region 11212 along the thickness direction of the permanent magnet 112 is 3.5 mm. 2max The value of 1.9 mm and the number of pole pairs p of the permanent magnet 112 is 3 are substituted into formulas (1)-(4) to obtain: k1=k2=4.94 mm 11 / 12 、k3=k4=4.24mm 11 / 12 .

[0132] Comparative Example 1

[0133] A rotor assembly 110 includes a rotor core 111 and permanent magnets 112. The rotor core 111 is provided with magnet slots 1111, within which the permanent magnets 112 are mounted. Diffusion regions 1121 are provided on the plane corresponding to the width and thickness of the permanent magnets 112. Diffusion regions 1121 include a first diffusion region 11211 and a second diffusion region 11212. The first diffusion region 11211 is located on one side of the width centerline of the permanent magnets 112, while the second diffusion region 11212 is located on the other side of the width centerline of the permanent magnets 112. The rotor core 111 is constructed from a plurality of stacked silicon steel sheets, and the permanent magnets 112 are radially magnetized.

[0134] The difference between the permanent magnets of Comparative Example 1 and Application Example 1 is that Comparative Example 1 uses a permanent magnet with a size / brand of 1.9×13×40 / 42SH, but the permanent magnet is not coated with any slurry containing rare earth elements, that is, it does not contain a diffusion zone, and the motor parameters do not satisfy the operational relationship of formulas (1)-(4) of the present invention.

[0135] Performance Testing

[0136] The demagnetization rate of the motor 100 and the intrinsic coercive force of the permanent magnet of Application Example 1 and Comparative Example 1 were tested. The specific testing process of the demagnetization rate is as follows:

[0137] First, the rotor assembly 110 that is magnetized and saturated is placed at room temperature, and the magnetic flux of the rotor assembly 110 is measured. After the initial magnetic flux is tested, the rotor assembly 110 is placed in a constant temperature box for more than 4 hours, and the temperature of the constant temperature box is set to the specified temperature (130°C); then the test DC motor is connected to the DC power supply, and the demagnetization current is set according to the pre-set demagnetization current value (43A, 50A, etc.). When ready, the rotor assembly 110 is taken out of the constant temperature box, and the demagnetization test fixture is installed. The rotor assembly rotates one circle under the DC demagnetization current; after completion, the rotor assembly 110 is placed at room temperature for more than 4 hours, and then the temperature of the rotor assembly 110 and the magnetic flux after demagnetization are measured.

[0138] Calculate the demagnetization rate, the calculation formula is as follows: (calculation time Need to use Same temperature):

[0139]

[0140] in: is the magnetic flux of the rotor assembly 110 at the beginning of the demagnetization test; is the magnetic flux of the rotor assembly 110 after the demagnetization test at the i-th demagnetization current value. The test results are shown in Table 1:

[0141] Table 1: Performance comparison table of application example 1 and comparative example 1

[0142] performance Demagnetization rate at 130℃ / 50A (%) Intrinsic coercivity Application Example 1 2.65 1920KA / m Comparative Example 1 3.81 2070KA / m

[0143] As can be seen from Table 1, the permanent magnet with a specific diffusion zone provided by the present invention has an intrinsic coercive force increased by 150 kA / m compared to the permanent magnet without diffusion. At the same time, the demagnetization rate of the motor provided by the present invention can reach 2.65% at 50A / 130°C, which is 30.45% lower than that of ordinary motors, greatly reducing the production cost of the motor.

[0144] In addition, through a large number of experiments, it is found that when the parameters of the motor are the width w of the permanent magnet 112, the thickness h of the permanent magnet 112, the length T of the permanent magnet 112, the distance O2 from the end point of the permanent magnet 112 close to the outer circle of the rotor core 111 to the origin of the rotor core 111, and the maximum length L of the first diffusion region 11211 along the width direction of the permanent magnet 112, the permanent magnet 112 is the same as the permanent magnet 112. 1max , the maximum length W of the first diffusion region 11211 along the thickness direction of the permanent magnet 112 1max , the maximum length L of the second diffusion region 11212 along the width direction of the permanent magnet 112 2max , the maximum length W of the second diffusion region 11212 along the thickness direction of the permanent magnet 112 2max When the number of pole pairs p of the permanent magnet 112 does not satisfy the calculation relationship of the above formulas (1)-(4), it is not conducive to reducing the cost of the motor. 11 / 12 , k2 is less than 2.1mm 11 / 12 , k3 is less than 2.1mm 11 / 12 , k4 is less than 2.1mm 11 / 12 , the demagnetization effect of the motor is not good; when k1 is greater than 25.2mm 11 / 12 , k2 is greater than 25.2mm 11 / 12 , k3 greater than 18.3mm 11 / 12 , k4 is greater than 18.3mm 11 / 12 The demagnetization effect of the motor is similar to that of embodiment 1, but the cost is much higher than that of embodiment 1. Therefore, the cost performance of the motor is not high, and the cost is increased.

[0145] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0146] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0147] For those skilled in the art to which the present invention belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present invention, without having to resort to creative work. Therefore, based on the disclosure of the present invention, simple improvements made to the present invention by those skilled in the art should be within the scope of protection of the present invention. The above embodiments are preferred embodiments of the present invention, and any structures similar to the present invention and any equivalent changes made should fall within the scope of protection of the present invention.

Claims

1. A rotor assembly, characterized in that: include: A rotor core (111), wherein the rotor core (111) is provided with a magnet slot (1111); A permanent magnet (112) is disposed in the magnet slot (1111), and a diffusion region (1121) is provided on a plane where the width and thickness of the permanent magnet (112) are located. The diffusion region (1121) includes: A first diffusion region (11211) is provided on one side of a width center line of the permanent magnet (112); and / or A second diffusion region (11212) is arranged on the other side of the width center line of the permanent magnet (112); The first diffusion region (11211) and the second diffusion region (11212) both contain rare earth elements; Wherein: the width w of the permanent magnet (112), the thickness h of the permanent magnet (112), the length T of the permanent magnet (112), the distance O2 from an end point of the permanent magnet (112) close to the outer circle of the rotor core (111) to the origin of the rotor core (111), the maximum length L of the first diffusion region (11211) along the width direction of the permanent magnet (112), 1max , the maximum length W of the first diffusion region (11211) along the thickness direction of the permanent magnet (112) 1max , and the number of pole pairs p of the permanent magnet (112) satisfy the following formulas (1) and (2): In the above formula: 2.1≤k1≤25.2, 2.1≤k3≤18.

3.

2. The rotor assembly according to claim 1, wherein: The maximum length L of the second diffusion region (11212) along the width direction of the permanent magnet (112) 2max , the maximum length W of the second diffusion region (11212) along the thickness direction of the permanent magnet (112) 2max The following formulas (3) and (4) are satisfied: In the above formula: 2.1≤k2≤25.2, 2.1≤k4≤18.

3.

3. The rotor assembly according to claim 1 or 2, characterized in that: The rare earth element includes at least one of dysprosium, terbium, praseodymium, neodymium and cerium.

4. The rotor assembly according to claim 1 or 2, characterized in that: The rare earth elements are uniformly distributed or non-uniformly distributed in the diffusion zone (1121).

5. The rotor assembly according to claim 1 or 2, characterized in that: The content of the rare earth element in the first diffusion region (11211) accounts for a mass percentage g1 of 0.99%-2.2% of the permanent magnet (112).

6. The rotor assembly according to claim 5, wherein: The content of the rare earth element in the second diffusion region (11212) accounts for a mass percentage g2 of 0.99%-2.2% of the permanent magnet (112).

7. The rotor assembly according to claim 6, wherein: The permanent magnet (112) further includes a non-diffusion region (11214), wherein the content of rare earth elements in the non-diffusion region (11214) accounts for a mass percentage of g3 of the permanent magnet (112), and g3 <g1,g3<g2。 8. The rotor assembly according to claim 7, wherein: The permanent magnet (112) further comprises a plurality of third diffusion regions (11213), wherein the third diffusion regions are arranged between the first diffusion region (11211) and the second diffusion region (11212), and the content of the rare earth element in each of the third diffusion regions (11213) accounts for a mass percentage of g of the permanent magnet (112). i , g i >g3.

9. The rotor assembly according to claim 1, wherein: The first diffusion region (11211) and the second diffusion region (11212) are distributed over the entire area or partially along the axial direction of the permanent magnet (112).

10. The rotor assembly according to claim 1, wherein: The rotor assembly comprises a plurality of permanent magnets (112), and the diffusion regions (1121) on cross sections of the permanent magnets (112) having different widths and thicknesses are the same or different.

11. The rotor assembly according to claim 1, wherein: The permanent magnet (112) is magnetized radially or parallelly.

12. The rotor assembly according to claim 1, wherein: The rotor core (111) is formed by stacking a plurality of silicon steel sheets.

13. A motor, characterized in that: include: A rotor assembly as claimed in any one of claims 1 to 12.

14. A compressor, characterized in that: include: The rotor assembly according to any one of claims 1 to 12; or The motor as claimed in claim 13.

15. A refrigerator, characterized in that: include: The motor according to claim 13; or The compressor of claim 14.

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