JP4089705B2 - Multi-layered multipole magnet rotor - Google Patents

Description

  The present invention relates to a multilayered multipolar magnet rotor provided with a circumferential anisotropic layer, a radial anisotropic layer, and a boundary layer in which circumferential and radial direction anisotropic clusters are mixed as required.

In 1985, R.A. W. Lee et al reported the (BH) _max 111kJ / melt-spun powder m ³ was hardened with an epoxy resin (BH) isotropic Nd ₂ Fe ₁₄ B bonded magnet _{max 72kJ} / m ³ [R. W. Lee, et al, IEEE Trans. Magn. 21, 1958, (1985)] (see Non-Patent Document 1). In 1986, the present inventors [JP-A-61-38830] (see Patent Document 1), 1988, T.A. The motor characteristics of a radial magnetic anisotropic Sm-Co based magnet whose (BH) _max is reduced by a decrease in the orientation magnetic field when the diameter of the magnet is reduced by Simoda is compared with that of the former [Permanent magnets 1988 update, Wheeler Associate INC, (1988)]. After that, in 1989 W.C. Baran [The European business and technical outlook for NdFeB magnets, 11 (1989)], 1990, G.C. X. Huang [G. X. Huang, et al, Proc. 11th Int. Works on Rare-Earth Magnets and Ther Applications, Pittsburgh, 583, (1990)]. H. Kasai [Y. Kasai, Polymer
Bonded magnets '92, Embassy Suite O'Hare-Rosemont, Illinois, (1992)], etc. Isotropic Nd ₂ Fe ₁₄ B for miniaturization and higher output of PM stepping motors, DC motors, and BL (brushless) motors Reports on the usefulness of bonded magnets were made one after another. Therefore, since the 1990s, isotropic Nd ₂ Fe ₁₄ B bonded magnets with (BH) _max ˜80 kJ / m ³ have become widespread as magnets for improving the performance of small motors centering on PCs and their peripheral equipment. [S. Hirosawa, et
al, J. et al. Magn. Soc. Japan, 21, 160 (1997)] (see Non-Patent Documents 2, 3, 4, 5, 6).

However, even if the diameter is reduced, the radial (BH) _max will not decrease, and if high productivity is realized, the motor will have higher output, smaller and lighter, thinner, lower current consumption, and resource saving. Application and popularization of high (BH) _max radial anisotropic magnets to motors is expected.
In view of the above background, the present inventors self-assembled oligomers and polymers for fixing rare earth magnet powder by chemical contact to produce perpendicular magnetic anisotropic thin plate magnets containing macromolecules between crosslinks, and An attempt was made to make a rare earth bonded magnet that controls the flexibility caused by molecular orientation and changes the direction of anisotropy from the perpendicular direction to the radial direction. For example, RD (Reduction and Diffusion) -Sm ₂ Fe ₁₇ N ₃ fine powder [A. Kawamoto, T .; Ishikawa, S .; Yasuda, K .; Takeya, K .; Ishizaka, T .; Iseki, K .; Ohmori, “Sm ₂ Fe ₁₇ N ₃ magnet powder
made by reduction and diffusion method ", IEEE Trans.Magn., Vol.35, pp.3322-3324, (1999)] in HDDR- (Hydrogenation, Disproportionation, Desorption, and Recombination) -Nd 2 Fe 14 B particles [T Takeshita, et al, Proc. Of the 10th Int. Worksshop on Rare-Earth Magnets and Their Applications, Kyoto, vol. 1,551 (1989)], while isolating existing thermosetting resin molding materials. When compression molding is performed at a low pressure of 20 to 50 MPa, a full density with a relative density of 98% or more including a binder is obtained. Thin plate magnet was obtained. In particular,
In this method, generation of new surfaces and surface defects of HDDR-Nd ₂ Fe ₁₄ B particles in the molding process is suppressed, and (BH) _max exceeding 150 kJ / m ³ is obtained, and initial irreversible demagnetization rate up to 120 ° C. Is improved to less than half that of anisotropic Nd ₂ Fe ₁₄ B bonded magnets [for example, Fumitoshi Yamashita, Shinichi Tsutsumi, Eiji Toyoda, Hirotoshi Fukunaga, “Radial anisotropic rare earth bonded magnets utilizing molecular chain orientation ", The Institute of Electrical Engineers of Japan (A) Journal of Common Materials for Basic Materials, Vol. 124, no. 10, pp. 857-862 (2004)] (see, for example, Patent Documents 7, 8, and 9).
JP 61-38830 A R. W. Lee, et al, IEEE Trans. Magn. , 21, 1958, (1985) T.A. Simoda [Permanent magnets 1988 update, Wheeler Associate INC, (1988)] W. Baran [The European business and technical outlook for NdFeB magnets, 11 (1989)] X. Huang [G. X. Huang, et al, Proc. 11th Int. Works on Rare-Earth Magnets and Ther Applications, Pittsburgh, 583, (1990)] H. Kasai [Y. Kasai, Polymer bonded magnets '92, Embassiy Suite O'Hare-Rosemont, Illinois, (1992)] S. Hirosawa, et al, J. MoI. Magn. Soc. Japan, 21, 160 (1997) A. Kawamoto, T .; Ishikawa, S .; Yasuda, K .; Takeya, K .; Ishizaka, T .; Iseki, K .; Ohmori, "Sm2Fe17N3 magnet powder made by reduction and diffusion method", IEEE Trans. Magn. , Vol. 35, pp. 3322-3324 (1999) T.A. Takeshita, et al, Proc. of the 10th Int. works on Rare-Earth Magnets and Ther Applications, Kyoto, vol. 1,551 (1989) Fumitoshi Yamashita, Shinichi Tsutsumi, Hidetoshi Toyoda, Hirotoshi Fukunaga, “Radial Anisotropy Rare Earth Bond Magnets Using Molecular Chain Orientation”, The Institute of Electrical Engineers of Japan (A) Journal of Basic Materials, Vol. 124, no. 10, pp. 857-862 (2004)

The current state of research and development of a flexible thick film magnet that is indispensable for the multi-layer multi-pole magnet rotor according to the present invention is described in J. Org. Topfer et al. Have a thickness of 400-800 μm and (BH) _max 40 kJ / m ³ [J. Topfer, B.M. Pawlowski, “Thermal stability of rare-earth magnet thick film”, ICM 2003-Roma, Italy, (2003), 5P-pm-06]. However, the (BH) _max of ferrite sintered magnets is not as high as 80 kJ / m ³ of isotropic Nd ₂ Fe ₁₄ B magnets. To improve the performance of the magnet motor, for example, (BH) _max ≧ 140 kJ / m ³ magnets are required.

The reason for this is that the square root of the ratio of (BH) _max of different magnets is the approximate ratio of the gap magnetic flux density between the magnet and the iron core in the motor. For example, in the case of a magnet having (BH) _max of 140 and 80 kJ / m ³ , the ratio of the gap magnetic flux density is predicted to be about 1.32 times.

The inventors of the present invention have an initial irreversible demagnetization factor of up to 120 ° C. with a (BH) _max exceeding 140 kJ / m ³ and less than half that of an anisotropic Nd ₂ Fe ₁₄ B bonded magnet, and isotropic Nd ₂ Fe _14. Radial magnetic anisotropic magnets improved to the same extent as B magnets [for example, Fumitoshi Yamashita, “Preparation and Properties of Self-Organized Radial Anisotropic Rare Earth Bond Magnets”, Journal of Japan Society of Applied Magnetics, Vol. 29, pp. 185-191 (2005)] has been studied as a radial anisotropic magnet motor used in, for example, a 15-50 W home appliance air conditioner and information-related energy consuming equipment, but has not yet been put into practical use.

  The obstacles to practical use are (1) weakness of motor value (performance vs. cost) compared to existing magnets, (2) durability such as demagnetization resistance against a reverse magnetic field at 120 ° C, and (3) increased cogging torque For example, there is a decrease in quietness such as an increase in noise vibration accompanying a decrease in the accuracy or a decrease in stop position accuracy.

  The cogging torque is a torque pulsation caused by a change in the permeance coefficient Pc with the iron core as the rotor rotates because teeth and slots exist on the outer peripheral surface of the iron core facing the magnet.

  Therefore, the object of the present invention is to technically eliminate obstacles to the application of radial anisotropic magnets to motors such as those used for 15-50W home appliance air conditioning and information-related energy consuming equipment, thereby reducing power consumption and downsizing. The new type of magnet motor contributes to society.

  Specifically, (1) Strengthening price competitiveness by reducing the amount of rare earth magnet powder input to the motor by multilayering of magnets, (2) Increasing the demagnetization resistance due to the reverse magnetic field under high temperature exposure at 100 to 120 ° C (3) Sinusoidal gap magnetic flux density distribution for quietness and high precision of position control, (4) Motor value of radial anisotropic magnet motor by high efficiency such as motor loss reduction The goal is to eliminate (performance vs. cost) vulnerabilities.

  The present invention is a multi-layered multipolar magnet rotor provided with a circumferential anisotropic layer, a radial anisotropic layer, and a boundary layer in which circumferential anisotropy and radial anisotropic clusters are mixed if necessary.

  The present invention relates to a multi-layer structure magnet composed of an in-plane anisotropic layer, a plane vertical anisotropic layer, and, if necessary, a boundary layer in which circumferential and radial anisotropic clusters coexist. A structure in which the direction of in-plane and in-plane perpendicular anisotropy is changed to the circumferential direction and radial direction, respectively, by utilizing the flexibility of stretching the macromolecule between cross-links of the magnet. This is a multi-layered multi-pole magnet rotor.

More preferably, the multilayer structured magnet has a thickness of 1350 μm or less, (BH) _{max of} the circumferential direction and radial direction anisotropic layer is 140 kJ / m ³ or more, and the multilayer in which the circumferential direction anisotropic layer is supported by a nonmagnetic member. The structure is a multipolar magnet rotor.

The multilayer multipolar magnet rotor having a configuration in which the circumferential magnetization according to the present invention, the radial magnetization, and a boundary layer in which circumferential anisotropy and radial anisotropy clusters are mixed are provided as needed. Thus, even if the ratio of the inner diameter and the outer diameter of the magnet exceeds 0.4, the generated magnetic flux density can be reduced and the magnetic flux density distribution can hardly be changed by the effect of the circumferential magnetization component. For this reason, it is possible to reduce the thickness (thick film) of the multilayer structure magnet. As a result, resource saving and price competitiveness can be enhanced by reducing the amount of expensive rare earth magnet material input. Further, since the magnetic path from the magnetic pole center becomes long, high permeance can be achieved. Therefore, it is possible to increase the motor output and improve the demagnetization resistance. In addition, since the surface magnetic flux density distribution has a sine wave shape, it is possible to achieve noise reduction and high accuracy of position control.

As described above, the new multi-layered multi-pole magnet rotor of (BH) _max ≧ 140 kJ / m ³ and multi-layered structure including circumferential magnetization according to the present invention is particularly suitable for home appliance air conditioning equipment of 15-50 W, information It can be expected to contribute to resource saving and energy saving promotion by miniaturization and high efficiency of motors used in related energy consuming equipment.

In the embodiment, the multi-layer structure multi-pole magnet rotor is disclosed based on the Sm ₂ Fe ₁₇ N ₃ / Nd ₂ Fe ₁₄ B multilayer structure magnet. However, for example, SmCo ₅ type fine powder can be used as an alternative to Sm ₂ Fe ₁₇ N _3. Needless to say, Sm ₂ TM ₁₇ (TM is a transition metal such as Co, Fe, Cu, and Zr) particles can be used as an alternative to Nd ₂ Fe ₁₄ B.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of a multilayer structure magnet according to the present invention. However, the independent hexagons in the figure represent, for example, crystal grains of single-domain particle type Sm ₂ Fe ₁₇ N ₃ fine powder, and the assembled hexagons represent crystal grains of polycrystalline aggregated Nd ₂ Fe ₁₄ B particles, The arrows shown therein indicate the easy axis of magnetization and its direction. In the figure, 1 is an in-plane anisotropic layer, 2 is a boundary layer, 2-1 and 2-2 are in-plane and plane vertical anisotropic clusters, 3 is a plane vertical anisotropic layer, and X is a stretching direction. Show.

  The present invention has, for example, a three-layer structure in which an in-plane anisotropic layer 1, a boundary layer 2 in which in-plane and in-plane vertical anisotropy clusters 2-1 and 2-2 are mixed, and a plane vertical anisotropic layer 3 are arranged. Thus, the multilayer structure magnet 0 has an overall thickness of about 900 μm. Alternatively, there may be a configuration in which the boundary layer 2 is eliminated and the plane perpendicular anisotropic layer 1 and the plane perpendicular anisotropic layer 3 are used as the multilayer structure magnet 0.

  The multilayer magnet 0 as described above according to the present invention includes an inter-crosslinking macromolecule generated by self-assembly of a binder. And the macromolecule between bridge | crosslinking contained in the multilayer structure magnet 0 is extended | stretched in the X direction in a figure, for example.

FIG. 2 is a conceptual diagram of stretching of macromolecules between crosslinks by rolling. In the figure, 0 represents a multilayer structured magnet before rolling, 0 ′ represents a multilayer structured magnet after rolling, R represents a constant speed rolling roll, and X represents a stretching direction. In order to change the direction of in-plane and plane perpendicular anisotropy into the circumferential direction and radial direction by such rolling, for example, a rolling reduction of 3 to 5% is sufficient. Further, when the thickness of the multilayer structured magnet 0 is 1350 μm or less, the magnetic characteristics represented by (BH) _max can be maintained.

  FIG. 3 is a conceptual diagram of multipolar magnetization of the multilayer structure magnet 0. In the figure, 1 is an in-plane anisotropic layer, 2 is a boundary layer, 3 is a plane perpendicular anisotropic layer, N and S are magnetic poles with multipolar magnetization, = is an easy axis and its orientation, and → is multipolar. The magnetization distribution in a magnetized magnet is shown. As shown in the figure, when the multilayer structured magnet 0 according to the present invention is composed of the plane perpendicular anisotropic layer 3, the boundary layer 2, and the in-plane anisotropic layer 1, the magnetic poles N and S are the plane perpendicular anisotropic layer 3. Provide on the side. Then, the magnet is magnetized from the magnetic pole S to the magnetic pole N through 3 → 2 → 1 → 2 → 3. Then, the magnetic path at the center of the magnetic poles N and S becomes the longest, and the magnetic path becomes shorter as the distance from the center of the magnetic poles N and S becomes longer, and the surface magnetic flux density distribution approaches a sine wave shape.

  As a suitable multipolar magnetizing method in the multi-layered multipolar magnet having a sinusoidal magnetization distribution as described above, the in-plane and plane perpendicular anisotropy directions are set in the circumferential direction, respectively, after multipolar magnetization. In addition, it is desirable to change in the radial direction.

  Specific multipolar magnetization of the multilayer magnet according to the present invention as described above will be described in detail below with reference to the drawings.

  FIG. 4 is a characteristic diagram showing the distribution of the in-plane direction pulse magnetic field component Hx and the vertical direction pulse magnetic field component Hy generated by the multipolar magnetized yoke. However, it is a pulse magnetic field distribution generated by energizing (crest value Ip25 kA) to a plane magnet having a distance between magnetic poles of 8.6 mm and a magnetic pole width of 1.7 mm and an excitation winding (conductor diameter 2 mm × 4 turn / coil). .

  As shown in FIG. 4, the center of each magnetic pole has a peak in the perpendicular magnetic field Hy acting on the vertical anisotropic layer 3, and the value reaches about 2.5 MA / m. On the other hand, between the magnetic poles, Hx acting on the in-plane anisotropic layer 1 exceeds Hy, and the value is estimated to exceed 1.5 MA / m.

FIG. 5 is a characteristic diagram showing the dependency of (BH) _{max on} the applied magnetic field MA / m of the Sm ₂ Fe ₁₇ N ₃ / Nd ₂ Fe ₁₄ B multilayered structure magnet 0 and the isotropic Nd ₂ Fe ₁₄ B magnet according to the present invention. It is. As shown in the figure, when the C axis forms an angle θ with the magnetization (multipolar magnetization) direction in each layer of the Sm ₂ Fe ₁₇ N ₃ / Nd ₂ Fe ₁₄ B multilayer structure magnet 0, A magnetic field Hm that is 1 / cos θ times the coercive force (about 1 MA / m) is required. However, in the magnetization in the easy axis (C axis) direction, that is, in the anisotropic direction in each layer, a magnetization exceeding HB of about 1.4 MA / m and exceeding (BH) _max 140 kJ / m ³ can be obtained. . Their values reach 1.75 to 2 times the (BH) _{max of} about 80 kJ / m ³ for isotropic Nd ₂ Fe ₁₄ B magnets. In addition, since the magnetic path of multipolar magnetization is due to in-plane (finally circumferential) magnetization, the permeance coefficient is higher than that of the isotropic Nd ₂ Fe ₁₄ B magnet, and higher magnetic flux It is obtained with a sinusoidal distribution.

  If the multipolar magnetization method is optimized as described above, the multipolar magnetization state of the multilayer structured magnet 0 according to the present invention as shown in FIG. 3 can be obtained.

  The number of magnetic poles and the distance between the magnetic poles are left to the motor design concept.

  In the present invention, the in-plane and plane perpendicular anisotropy directions of the multi-layered magnet 0 subjected to the multipolar magnetization as described above are changed into a circumferential direction and a radial direction, respectively. A multi-layered multi-pole rotor having a structure fixed to a magnetic member is used.

  FIG. 6 shows a new configuration in which an 8-pole multilayered multi-pole magnet rotor (c) according to the present invention is combined with an iron core in comparison with a conventional radial anisotropic magnet motor (a) and Halbach magnet motor (b). The cross-section figure of the magnet motor of is shown. In the figure, 4a-1 is a radial anisotropic magnet, 4b-1 is a Halbach magnet, 4c-1 is multipolar magnetized, and then the in-plane and plane perpendicular anisotropy directions are set in the circumferential direction and radial direction, respectively. It is a multi-layered structure magnet that has been converted to Reference numerals 4a-2, 4b-2, and 4c-2 denote stator cores, and 4b-3 denotes a soft magnetic material, which is a radial anisotropic magnet back yoke.

  Compared to the radial anisotropic magnet motor of FIG. 6A, the Halbach magnet motor of FIG. 6B can increase the peak value of the surface magnetic flux density by about 1.5 times with the same magnet material. Further, since the surface magnetic flux density distribution is sinusoidal compared to the rectangular wave of (a), (b) approaches an ideal magnet rotor. However, in the Halbach magnet motor (b), when the number of magnetic poles of the rotor is 8, when the ratio of the magnet inner diameter to the outer diameter exceeds 0.4, the magnetic flux density generated by the magnet starts to decrease, and the ratio is about 0.8. The advantages over radial anisotropic magnets disappear [K. Atallah and D.C. Howe, “The Application of Halbach Cylinders to Brushless AC Server Motors”, IEEE Trans. Magn. Vol. 34. No. 4, pp. 2060-2063 (1998)].

For example, in a 15-50 W magnet motor used in home appliance air-conditioning equipment and information-related energy consuming equipment targeted by the present invention, for example, when the outer diameter of a rotor magnet having 8 magnetic poles is 50 mm, an ideal Halbach In order to use a magnet motor, the inner diameter of the magnet is required to be about 20 mm, and the magnet thickness is required to be about 15 mm. Further, when compared with a radial anisotropic magnet, in order to obtain the same magnetic flux density, the inner diameter of the magnet needs to be about 40 mm and the thickness of the magnet needs to be about 5 mm. In this case, industrial spread considers that there is a relatively inexpensive known magnet material as the (BH) _max 16kJ / m ³ even magnet turned in consideration of matching with the economy in the ferrite injection molding magnets extent There is a relatively large amount. Therefore, even if the magnet thickness is about 5 to 15 mm, it can be adopted. However, as is well known, in the case of an expensive rare earth magnet material whose price is estimated to be approximately 10 times or more compared with ferrite, the consistency with the economy is extremely poor. That is, in order to extract the original performance of the Halbach magnet as the performance of the motor, the amount of magnet material input cannot be reduced. For this reason, in the field of 15-50 W magnet motors, which are used in, for example, home appliance air conditioners and information-related energy consuming equipment, where price competition is particularly intense, expensive rare earth magnet materials are avoided.

  However, FIG. 6C according to the present invention is a multi-layered multi-pole magnet rotor having a configuration in which circumferential magnetization is performed on the rotating shaft side and radial magnetization is performed on the iron core side. In addition, a boundary layer in which circumferential anisotropy and radial anisotropy clusters are mixed can be provided as necessary. Therefore, even if the ratio between the inner diameter and the outer diameter of the magnet exceeds 0.6 to 0.8, as in the Halbach magnet rotor of FIG. The magnetic flux density distribution can be made difficult to change.

  As described above, the multi-layer structure multi-pole magnet rotor according to the present invention enables the multi-layer structure magnet 0 to be thin (thick film), resulting in resource saving and price competition by reducing the input amount of expensive rare earth magnet materials. Strengthen the power. Further, since the magnetic path from the magnetic pole center becomes long, high permeance can be achieved. Accordingly, it is possible to improve the demagnetization resistance of the motor with high output, reverse magnetic field, or high temperature exposure. In addition, since the surface magnetic flux density distribution is sinusoidal, there is a feature that noise reduction and high accuracy of position control can be achieved.

As described above, (BH) _max ≧ 140 kJ / m ³ according to the present invention, and the provision of a multi-layered multipolar magnet rotor having a new multi-layer structure, especially a 15-50 W home appliance air-conditioning apparatus, which is highly price-competitive, information It is understood that this is an innovative technology for promoting the conservation of resources and energy by miniaturization and high efficiency of motors used in related energy consuming equipment.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments disclosed herein.

  Hereinafter, a multilayer structured magnet composed of an in-plane anisotropic layer and a perpendicular anisotropic layer according to the present invention will be described.

However, as the anisotropic rare earth magnet powder, polycrystalline aggregate HDDR-Nd ₂ Fe ₁₄ B having a particle size of 38 to 150 μm and single domain particle type RD-Sm ₂ Fe ₁₇ N ₃ having a particle size of 3 to 5 μm were used. Among the binders, an oligomer as a magnet powder fixing component is an epoxy equivalent of 205 to 220 g / eq, a novolak type epoxy having a melting point of 70 to 76 ° C., and a polymer forming an intercrosslinking macromolecule has a melting point of 80 ° C. and a molecular weight of 4000 to 12000. The polyamide and chemical contacts used were imidazole derivatives having a melting point of 80 to 100 ° C., and pentaerythritol C17 triester having a melting point of about 52 ° C. as a lubricant. This consists of one hydroxyl group (—OH) and three hexadecyl groups having 16 carbon atoms (— (CH ₂ ) ₁₆ CH ₃ ) in one molecule. The polar group is compatible with the polymer, and the hexadecyl group is expected to lubricate between the magnet powder and the mold wall.

Granule compound is polymer of RD-Sm ₂ Fe ₁₇ N ₃ 38.20% by weight of oligomer 1% by weight and HDDR-Nd ₂ Fe ₁₄ B 57.44% by weight of oligomer 0.5% by weight. After melt-kneading at a melting point (120 ° C.) of 2.80% by weight and lubricant 0.28% by weight, cooling to room temperature, coarsely pulverizing to 350 μm or less, and then 0.28% by weight of chemical contact was dry-mixed at room temperature. Is.

Next, the granule compound is heated to 160 ° C., and compressed at 50 MPa in a melt flow state accompanied by slip in an orthogonal magnetic field (or parallel magnetic field) of 1.4 MA / m or more, and has a thickness of about 450 μm and a density of 5. An in-plane anisotropy or plane perpendicular anisotropic thick film magnet of 8 to 5.97 Mg / m ³ , (BH) _max ≧ 140 kJ / m ³ was produced.

  Subsequently, the in-plane and plane perpendicular anisotropic thick film magnets are overlapped, and the in-plane anisotropic layer containing the inter-crosslinking macromolecule according to the present invention is applied by heating and pressing at 180 ° C. and 10 MPa for about 20 minutes. A multilayer structure magnet composed of a conductive layer and having an average thickness of about 900 μm was produced.

  As described above, the multilayer structured magnet according to the present invention can be easily obtained by directly superposing in-plane anisotropy and plane perpendicular anisotropic thick film magnets and heating and pressing.

Hereinafter, a multilayer structure magnet composed of an in-plane anisotropic layer, a boundary layer, and a vertical anisotropic layer according to the present invention will be described. The same granule compound as in Example 1 was heated to 160 ° C. and compressed at 50 MPa in a melt flow state with slip in an orthogonal magnetic field (or parallel magnetic field) of 1.4 MA / m or more, thickness 450 μm, density 5 An in-plane (or plane perpendicular) anisotropic thick film magnet having a thickness of 0.8 to 5.97 Mg / m ³ and (BH) _max ≧ 140 kJ / m ³ was produced.

  Next, an in-plane (or plane perpendicular) anisotropic thick film magnet is accommodated in the bottom of the mold cavity, the upper surface thereof is filled with a granule compound having the same weight as the thick film magnet, heated to 160 ° C., and 1.4 MA The cross-linking macromolecule according to the present invention is contained by compressing at 50 MPa in a melt flow state with slip in an orthogonal magnetic field (or parallel magnetic field) of / m or more, and then heating and pressing at 180 ° C., 10 MPa for about 20 min. A multilayer magnet having an average thickness of 900 μm composed of an in-plane anisotropic layer, a boundary layer, and a vertical anisotropic layer was produced.

In the boundary layer, a part of the granule compound oriented in the direction perpendicular to the plane (or in-plane) is stored in advance in the bottom of the cavity and is softened by heating. It is generated by being pushed by the compression force.
As described above, the multilayer structured magnet according to the present invention can be easily obtained by forming a granule compound in an in-plane (or plane perpendicular) anisotropic thick film magnet in an orientation magnetic field having different directions.

  The multilayer magnet having a thickness of about 900 μm according to the present invention obtained in Examples 1 and 2 was rolled as shown in FIG. If the rolling reduction is about 4% and the thickness is about 860 μm, the in-plane and vertical anisotropy directions can be set in the circumferential direction as long as it is flexible in the rolling direction due to the stretching effect of the inter-crosslinking macromolecule contained in the magnet. It was confirmed that the direction can be changed as well as the radial direction.

An excitation winding (conductor) having a distance between magnetic poles of 8.6 mm and a magnetic pole width of 1.7 mm from the surface perpendicular anisotropy layer side of the approximately 860 μm thick multilayer structure magnet according to the present invention obtained in Example 3 and having flexibility. A plane magnetizer having a diameter of 2 mm × 4 turn / coil) was energized (crest value Ip 25 kA) and pulse magnetized. Thereafter, the direction of in-plane and perpendicular anisotropy is changed to the circumferential direction and the radial direction, respectively, and fixed to a nonmagnetic member having a rotating shaft, thereby having a diameter of 50.3 m.
m and a multilayered multipolar magnet rotor having a length of 24 mm.

  Table 1 summarizes the characteristics of the multi-layered multi-pole magnet rotor according to the present invention compared with the conventional magnet rotor shown in FIG.

ただし、表１に示す○×は相対比較で○は優位性が高いことを表している。また、比較例１の磁石の内外径比に関しては、本発明にかかる多層構造多極磁石ロータに準じて作製すれば、厚さ約８６０μｍのラジアル異方性磁石が作製できるため、当該磁石ロータの磁石の内外径比を０．９６５とした。加えて、ハルバッハ磁石ロータは磁極数４〜１２において、前記ラジアル異方性磁石ロータと同等以上の磁束密度が得られる磁石の内外径比０．６〜０．８とした［Ｋ．Ａｔａｌｌａｈ ａｎｄ Ｄ．Ｈｏｗｅ，“Ｔｈｅ Ａｐｐｌｉｃａｔｉｏｎ ｏｆ Ｈａｌｂａｃｈ Ｃｙｌｉｎｄｅｒｓ ｔｏ Ｂｒｕｓｈｌｅｓｓ ＡＣ Ｓｅｒｖｏ Ｍｏｔｏｒｓ”， ＩＥＥＥ Ｔｒａｎｓ．Ｍａｇｎ．Ｖｏｌ．３４．Ｎｏ．４，ｐｐ．２０６０−２０６３（１９９８）］。

However, ○ × shown in Table 1 indicates relative comparison, and ○ indicates that the superiority is high. In addition, regarding the inner / outer diameter ratio of the magnet of Comparative Example 1, a radial anisotropic magnet having a thickness of about 860 μm can be manufactured if manufactured according to the multilayered multipolar magnet rotor according to the present invention. The inner / outer diameter ratio of the magnet was 0.965. In addition, the Halbach magnet rotor has an inner / outer diameter ratio of 0.6 to 0.8 in which the magnetic flux density is equal to or higher than that of the radial anisotropic magnet rotor in the number of magnetic poles 4 to 12 [K. Atallah and D.C. Howe, “The Application of Halbach Cylinders to Brush AC Servo Motors”, IEEE Trans. Magn. Vol. 34. No. 4, pp. 2060-2063 (1998)].

  As described above, the multi-layered multi-pole magnet rotor according to the present invention eliminates the disadvantages of the conventional radial anisotropic magnet rotor and Halbach magnet rotor as shown in FIG. It turns out that it is a feature.

The present inventors manufactured a magnet rotor having a diameter of 50.3 mm and different orientation from (BH) max, and published a comparison of their motor efficiency η [F. Yamashita, A .; Watanabe H.M. Fukunaga, “Highly-Dense Anisotropic
Sm-Fe-N-Based Bonded Magnets Inclusion Uncounted Polymer Prepared by Powder
"Compacting Press", IEEE Trans. Magn., Vol. 39, pp. 2896-2898 (2003)].

  Table 2 collectively shows the main specifications of the multi-layered multi-pole magnet motor of Example 4 according to the present invention as motor efficiency η, with Comparative Example 1 to 3 as magnetic rotors having different orientations from (BH) max. However, the motor specification is 12 slots, 8 poles, 3 phases, the gap distance between the rotor magnet and the iron core is 0.5 mm, and the motor efficiency η is a value at a torque of 550 mNm.

First, the relationship between the (BH) max of different magnets and the motor efficiency η is arranged based on the Halbach magnet of Comparative Example 2 from the results in Table 2. When the motor magnetic circuit composed of a magnet and an iron core is the same, the square root X of the (BH) _max ratio of different magnets generally represents the ratio of the gap magnetic flux density. Therefore, FIG. 7A shows the relationship between the square root X of the ratio of (BH) _max and the motor efficiency η. Then, as shown in the figure, in Comparative Examples 1 to 3, the linear approximation (correlation coefficient = 1) is established as η = 4.8667X + 74.137. Therefore, when the linear approximation is extrapolated and compared with the motor efficiency η of the multilayered multipolar magnet rotor of the present invention example, it is clearly positioned on the higher efficiency side than the extrapolated line.

On the other hand, the relationship between the magnet insertion amount C and the motor efficiency η is shown in FIG. As shown in the figure, the relationship between the magnet insertion amount C and the motor efficiency η is found to be a power approximation of η = 79.937C ^−0.0747 (correlation coefficient = 0.9914) in all examples including the example of the present invention.

The characteristics of the multi-layer structure multi-pole magnet rotor according to the present invention can be summarized from FIGS. 7 (a) and 7 (b) as described above. Even if the amount is reduced, the high permeance multipolar magnetization pattern as shown in FIG. 3 is maintained. Therefore, as shown in Table 2, the amount of magnet input is reduced to 1/2 of the isotropic Nd ₂ Fe ₁₄ B magnet or 2/3 of the radial anisotropic Sm ₂ Fe ₁₇ N ₃ / Nd ₂ Fe ₁₄ B magnet. Even if it suppresses, the gap magnetic flux density more than the square root of (BH) _max ratio is obtained by the effect of high permeance. It can be concluded that this is the main reason for reducing both the amount of magnet input and improving the motor efficiency, compared with the existing magnet motor shown in the comparative example.

  A multi-layered multi-pole magnet rotor having a configuration in which a circumferential layer magnetization, a radial direction magnetization, and a boundary layer in which a circumferential anisotropy and a radial anisotropy cluster are mixed as necessary is provided. Resource saving by downsizing and high efficiency of motors used in 15-50W home appliance air conditioners and information-related energy consuming equipments by output, improvement of demagnetization resistance, noise reduction, and high precision of position control. Useful for promoting energy saving.

Conceptual diagram of multilayer magnet Conceptual drawing of stretching of macromolecules between crosslinks Conceptual diagram of multipolar magnetization of multilayer magnet Characteristics of in-plane and vertical magnetic field component distribution (BH) Characteristic diagram showing the dependence of _{max on} the applied magnetic field Structural diagram of each motor (a) Radial diagram, (b) Halbach diagram, (c) Multi-layer diagram (A) (BH) Characteristic diagram showing the relationship between the square root of the _max ratio and motor efficiency, (b) Characteristic diagram showing the relationship between the amount of magnet input and motor efficiency

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 In-plane anisotropic layer 2 Boundary layer 2-1, 2-2 In-plane and plane perpendicular anisotropic cluster 3 Plane perpendicular anisotropic layer X Stretching direction

Claims (4)

In a multi-layer structured magnet composed of an in-plane anisotropic layer , a boundary layer in which in-plane anisotropy clusters and in-plane anisotropy clusters are mixed , and a vertical anisotropy layer,
Multipolar magnetization with the vertical anisotropic layer side as the magnetic pole,
By rolling, utilizing the flexibility due to stretching of macromolecules between crosslinks of the magnet,
The direction of in-plane anisotropy layer and perpendicular anisotropy layer, respectively the circumferential direction, and a multi-layer structure multipolar magnetic rotor that is converted in the radial direction. The multilayered multipolar magnet rotor according to claim 1 , wherein the multilayered magnet has a thickness of 1350 μm or less. Plane anisotropy layer, and the multilayer structure multipolar magnet rotor according to claim 1 or claim 2 maximum energy product of the perpendicular anisotropy layer (BH) MAX is 140 kJ / m3 or more. The multi-layer structure multipolar magnet rotor according to any one of claims 1 to 3 , wherein the in-plane anisotropic layer is supported by a nonmagnetic member.

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