JP2016032023A - Permanent magnet, method of manufacturing permanent magnet, dynamo-electric machine and method of manufacturing dynamo-electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet in which the maximum magnetic flux density is enhanced, a method of manufacturing a permanent magnet, a dynamo-electric machine using the permanent magnet and a method of manufacturing a dynamo-electric machine.SOLUTION: A compound 17 is produced by pulverizing a magnet material into magnet powder, and then mixing the pulverized magnet material and a binder. A green sheet 19 is then created by molding the compound 17 thus produced like a sheet. Thereafter, magnetic field orientation is performed by applying a magnetic field to the green sheet 19 thus molded, and the green sheet 19 subjected to magnetic field orientation is deformed and molded into the product shape. Finally, it is sintered and a permanent magnet is produced. The permanent magnet has a ring-shape, and is configured so that the easy axis of magnetization is oriented while inclining to converge in the direction of the convergence axis set in parallel with the axial direction of the ring shape.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a permanent magnet, a method for manufacturing a permanent magnet, a rotating electrical machine, and a method for manufacturing a rotating electrical machine.

  In recent years, in machine tools, vehicles, aircraft, wind power engines, etc., a generator that converts mechanical kinetic energy transmitted from an engine into electrical energy, or a motor that converts electrical energy into mechanical kinetic energy ( A rotating electrical machine such as an electric motor is generally used. Further, there is a demand for further increases in torque and power generation amount of the rotating electrical machine.

  Here, as a manufacturing method of a permanent magnet used for a rotating electrical machine, a powder sintering method has been generally used. Here, in the powder sintering method, first, magnet powder obtained by pulverizing raw materials by a jet mill (dry pulverization) or the like is manufactured. Thereafter, the magnet powder is put into a mold and press-molded into a desired shape. And it manufactures by sintering the solid magnet powder shape | molded by the desired shape at predetermined temperature (for example, 1100 degreeC in a Nd-Fe-B type magnet) (for example, Unexamined-Japanese-Patent No. 2-266503). In general, permanent magnets are magnetically oriented by applying a magnetic field from the outside in order to improve magnetic characteristics. In the conventional method for producing a permanent magnet by powder sintering, a magnet powder is filled into a mold at the time of press molding, and a magnetic field is applied to orient the magnetic field, and then pressure is applied to form a compacted compact. Was. Moreover, in the manufacturing method of the permanent magnet by other extrusion molding methods, injection molding methods, rolling molding methods, etc., a magnet was molded by applying pressure in an atmosphere to which a magnetic field was applied. Accordingly, it is possible to form a molded body in which the easy magnetization (C-axis) direction of each magnet particle constituting the permanent magnet is aligned with the magnetic field application direction.

  Here, there are axial anisotropy, radial anisotropy, polar anisotropy and the like as a method of aligning the easy magnetization axes of the anisotropic magnets. In addition, when using an anisotropic magnet for a rotary motive, instead of orienting the easy axis of magnetization of each magnet particle in the same direction (that is, in parallel), for the purpose of reducing torque ripple and improving driving force, The easy axis of magnetization has been oriented in the direction in which the magnetic flux of the magnetized anisotropic magnet is concentrated (for example, JP-A-2005-287181).

JP-A-2-266503 (page 5) Japanese Patent Laying-Open No. 2005-287181 (5th page, FIG. 2)

  Here, the rotating electrical machine accommodates the rotor (rotor) on the inner side and the inner rotor type with the stator (stator) arranged on the outer side, or the inner rotor type, the stator on the inner side and the rotor on the outer side. A cylindrical rotating electric machine such as an outer rotor type that is arranged and rotated outside is often used. On the other hand, there is an axial gap type rotating electrical machine in which a stator and a rotor arranged in a disk shape instead of a cylindrical type rotate opposite to each other. In the axial gap type rotating electrical machine, since the components can be arranged thinner than the cylindrical type, it is possible to reduce the size of the device.

  Also in the axial gap type rotating electrical machine, it has been required to optimize the orientation direction of the easy axis of the anisotropic magnet used in the rotating electrical machine.

  The present invention has been made to solve the above-described problems in the prior art, and for a ring-shaped permanent magnet disposed in an axial gap type rotating electrical machine or the like, the maximum magnetic flux density is improved by concentrating the magnetic flux, It is an object of the present invention to provide a permanent magnet that realizes an increase in torque and power generation amount of a rotating electrical machine, a method for manufacturing the permanent magnet, a rotating electrical machine using the permanent magnet, and a method for manufacturing the rotating electrical machine.

  In order to achieve the above object, the permanent magnet according to claim 1 of the present application has a ring shape, and a plurality of magnetic poles are formed along the circumferential direction on the axial surface of the ring shape. The easy magnetization axis is tilted and oriented so as to focus in a direction along a focusing axis set parallel to the axial direction.

  A permanent magnet according to a second aspect is the permanent magnet according to the first aspect, wherein the shape of the magnetic flux density distribution in the circumferential direction of the surface in the axial direction is a sine wave shape.

  A permanent magnet according to claim 3 is the permanent magnet according to claim 1 or 2, wherein the step of pulverizing the magnet raw material into magnet powder, and the pulverized magnet powder and a binder are mixed. Producing a mixture, a step of magnetic field orientation by applying a magnetic field to the mixture, and a step of sintering by holding a compact of the mixture oriented at a firing temperature at a firing temperature. It is characterized by being.

  The permanent magnet according to claim 4 is the permanent magnet according to claim 3, wherein in the magnetic field orientation step, a magnetic field is applied to the mixture, and the mixture to which a magnetic field is applied is The magnetic field orientation is performed by manipulating the direction of the easy magnetization axis by deforming into a compact.

  The permanent magnet according to claim 5 is the permanent magnet according to claim 4, wherein, in the magnetic field orientation step, after the mixture is formed into a sheet shape, a magnetic field is applied to the sheet-like mixture. It is characterized by that.

  A permanent magnet according to a sixth aspect is the permanent magnet according to any one of the first to fifth aspects, wherein the permanent magnet is disposed in a stator or a rotor of an axial gap type rotating electrical machine, and the stator Alternatively, it is characterized in that the easy magnetization axis is inclined toward the air gap side along the circumferential direction of the rotor.

  A permanent magnet according to a seventh aspect is the permanent magnet according to the sixth aspect, wherein when the magnet is disposed and magnetized in the stator or rotor of the rotating electrical machine, the magnetic flux inside the magnet is moved to the air gap side. It is characterized by being concentrated.

  A rotating electric machine according to an eighth aspect is an axial gap type rotating electric machine, wherein the permanent magnet according to any one of the first to seventh aspects is arranged in a stator or a rotor.

  The method for producing a permanent magnet according to claim 9 is a method for producing a permanent magnet having a ring shape in which a plurality of magnetic poles are formed along the circumferential direction on the surface in the axial direction, and the magnet raw material is pulverized into magnet powder. A step of generating a mixture in which the pulverized magnet powder and a binder are mixed, a step of magnetic field orientation by applying a magnetic field to the mixture, and a compact of the mixture that is magnetically oriented. In the step of magnetic field orientation, the magnetic field orientation step is set parallel to the axial direction of the ring shape for each of the magnetic poles. The easy magnetization axis is inclined and oriented so as to focus in a direction along the focusing axis.

  Moreover, the manufacturing method of the permanent magnet which concerns on Claim 10 is a manufacturing method of the permanent magnet of Claim 9, Comprising: In the said magnetic field orientation process, the circumferential direction of the said axial direction surface of the manufactured said permanent magnet The magnetic flux density distribution is oriented so as to have a sine wave shape.

  A method for producing a permanent magnet according to claim 11 is the method for producing a permanent magnet according to claim 9 or 10, wherein, in the step of orienting the magnetic field, a magnetic field is applied to the mixture. The magnetic field is oriented by manipulating the direction of the easy axis of magnetization by deforming the mixture to which a magnetic field has been applied into the shaped body.

  Moreover, the manufacturing method of the permanent magnet which concerns on Claim 12 is a manufacturing method of the permanent magnet of Claim 11, Comprising: In the process of aligning the said magnetic field, after shape | molding the said mixture in a sheet form, the said sheet-like said A magnetic field is applied to the mixture.

  A method for manufacturing a permanent magnet according to claim 13 is the method for manufacturing a permanent magnet according to any one of claims 9 to 12, wherein the permanent magnet is a stator or rotor of an axial gap type rotating electrical machine. The easy-magnetization axis is inclined to the air gap side along the circumferential direction of the stator or the rotor.

  A method for producing a permanent magnet according to claim 14 is the method for producing a permanent magnet according to claim 13, wherein the permanent magnet is arranged on the stator or rotor of the rotating electrical machine and magnetized when the magnet is arranged and magnetized. The magnetic flux inside the magnet concentrates on the heel.

  Furthermore, the manufacturing method of the rotary electric machine which concerns on Claim 15 is a manufacturing method of an axial gap type rotary electric machine, Comprising: The permanent magnet manufactured by the manufacturing method in any one of Claim 9 thru | or 14 is made into a stator or a rotor. It is characterized by manufacturing by arrange | positioning.

  According to the permanent magnet of claim 1, having the above-described configuration, the easy magnetization axis is inclined and oriented so as to converge in a direction along the focusing axis set parallel to the ring-shaped axial direction. On the axial surface on which the magnetic poles are formed, the magnetic flux can be appropriately concentrated after magnetization, and the maximum magnetic flux density can be improved and variations in the magnetic flux density can be prevented. In particular, in an axial gap type rotating electrical machine, if the permanent magnet is disposed in the stator or rotor, the maximum magnetic flux density is improved by concentrating the magnetic flux on the air gap side, and the rotating electrical machine in which the permanent magnet is disposed. Torque and power generation can be improved and torque ripple can be reduced.

  According to the permanent magnet of the second aspect, the waveform of the magnetic flux density distribution in the circumferential direction of the ring-shaped axial surface can be brought close to an ideal sine wave shape. As a result, torque ripple can be reduced, and the drive control of the rotating electrical machine can be accurately performed when installed in the rotating electrical machine.

According to the third aspect of the present invention, the easy-magnetization axis is appropriately focused in one direction along the focusing axis by forming a mixture in which the magnet powder and the binder are mixed. It becomes possible to orientate like this. As a result, it is possible to concentrate the magnetic flux appropriately after magnetization, thereby improving the maximum magnetic flux density and preventing variations in the magnetic flux density.
Further, since the mixture with the binder is molded, the magnet particles do not rotate after the orientation and the degree of orientation can be improved as compared with the case of using compacting or the like.
In addition, when magnetic field orientation is performed on a mixture with a binder, the number of current turns can be used, so that it is possible to ensure a large magnetic field strength when performing magnetic field orientation, and long-term magnetic field application with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with little variation. If the orientation direction is corrected after the orientation, it is possible to secure a highly oriented orientation with little variation.
Furthermore, the realization of high orientation with little variation leads to a reduction in variation in shrinkage due to sintering. That is, the uniformity of the product shape after sintering can be ensured. As a result, it can be expected that the burden on the external processing after sintering is reduced and the stability of mass production is greatly improved.

  According to the permanent magnet of claim 4, the orientation direction is corrected by deforming the magnetically oriented mixture, and the easy magnetization axis is appropriately focused in one direction along the focusing axis. It becomes possible to orient. As a result, it is possible to perform a highly oriented orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected simultaneously with the deformation to the molded body. As a result, the molding process and the orientation process of the permanent magnet can be performed in one process, and the productivity can be improved.

  In addition, according to the permanent magnet of claim 5, since the magnetic field orientation is performed after the mixture is once formed into a sheet shape, and then the molded body is deformed, the molding process and the magnetic field orientation process are efficiently performed in a continuous process. This can be done well, and productivity can be improved.

  Further, according to the permanent magnet of the sixth aspect, since the easy magnetization axis is inclined toward the air gap along the circumferential direction of the stator or rotor of the axial gap type rotating electrical machine, the permanent magnet is disposed on the stator or rotor and attached. When magnetized, the magnetic flux can be more concentrated on the air gap side. As a result, it is possible to improve the torque and power generation amount of the rotating electrical machine in which the permanent magnet is arranged.

  Further, according to the permanent magnet of the seventh aspect, when the permanent magnet is disposed in the stator or rotor of the axial gap type rotating electrical machine, it is possible to improve the torque and power generation amount of the rotating electrical machine in which the permanent magnet is disposed. It becomes.

  Further, according to the rotating electrical machine according to claim 8, in the axial gap type rotating electrical machine, the power generation of the generator is improved, the torque of the motor is increased, the motor is reduced in size, the torque ripple is reduced, and the efficiency is increased. Can be realized.

In addition, according to the method for manufacturing a permanent magnet according to claim 9, the easy magnetization axis is focused so as to be focused in a direction along a focusing axis set parallel to the axial direction of the ring shape of the manufactured permanent magnet. Since it is oriented in an inclined manner, it is possible to concentrate the magnetic flux properly after magnetization on the axial surface on which the magnetic pole is formed, thereby improving the maximum magnetic flux density and preventing the magnetic flux density from being varied. In particular, in an axial gap type rotating electrical machine, if the permanent magnet is disposed in the stator or rotor, the maximum magnetic flux density is improved by concentrating the magnetic flux on the air gap side, and the rotating electrical machine in which the permanent magnet is disposed. Torque and power generation can be improved and torque ripple can be reduced.
In addition, by forming a mixture of magnet powder and binder, the easy magnetization axis can be oriented so as to be properly focused in one direction along the focusing axis. As a result, it is possible to concentrate the magnetic flux appropriately after magnetization, thereby improving the maximum magnetic flux density and preventing variations in the magnetic flux density.
Further, since the mixture with the binder is molded, the magnet particles do not rotate after the orientation and the degree of orientation can be improved as compared with the case of using compacting or the like.
In addition, when magnetic field orientation is performed on a mixture with a binder, the number of current turns can be used, so that it is possible to ensure a large magnetic field strength when performing magnetic field orientation, and long-term magnetic field application with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with little variation. If the orientation direction is corrected after the orientation, it is possible to secure a highly oriented orientation with little variation.
Furthermore, the realization of high orientation with little variation leads to a reduction in variation in shrinkage due to sintering. That is, the uniformity of the product shape after sintering can be ensured. As a result, it can be expected that the burden on the external processing after sintering is reduced and the stability of mass production is greatly improved.

  Further, according to the method for manufacturing a permanent magnet according to the tenth aspect, the waveform of the magnetic flux density distribution in the circumferential direction of the axial surface of the ring shape of the permanent magnet can be brought close to an ideal sine wave shape. As a result, torque ripple can be reduced, and the drive control of the rotating electrical machine can be accurately performed when installed in the rotating electrical machine.

  According to the method for manufacturing a permanent magnet according to claim 11, the orientation direction is corrected by deforming the mixture once magnetically oriented, and the easy magnetization axis is appropriately set in one direction along the focusing axis. It becomes possible to orient so as to focus. As a result, it is possible to perform a highly oriented orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected simultaneously with the deformation to the molded body. As a result, the molding process and the orientation process of the permanent magnet can be performed in one process, and the productivity can be improved.

  Moreover, according to the method for producing a permanent magnet according to claim 12, since the magnetic field orientation is performed after the mixture is once formed into a sheet shape, and then the deformation into the molded body is performed, the molding process and the magnetic field orientation process are continuously performed. It is possible to perform efficiently in the process, and productivity can be improved.

  Further, according to the method for manufacturing a permanent magnet according to claim 13, since the easy magnetization axis is inclined toward the air gap along the circumferential direction of the stator or rotor of the axial gap type rotating electrical machine, the permanent magnet is disposed on the stator or rotor. In the case of being magnetized, the magnetic flux can be more concentrated on the air gap side. As a result, it is possible to improve the torque and power generation amount of the rotating electrical machine in which the permanent magnet is arranged.

  Further, according to the method of manufacturing a permanent magnet according to claim 14, when the manufactured permanent magnet is arranged in a stator or rotor of an axial gap type rotating electric machine, the torque of the rotating electric machine in which the permanent magnet is arranged. And the amount of power generation can be improved.

  Furthermore, according to the method for manufacturing a rotating electrical machine according to claim 15, in the axial gap type rotating electrical machine, the power generation of the generator is improved, the torque of the motor is increased, the motor is reduced in size, and the torque ripple is reduced as compared with the conventional method. It is possible to achieve high efficiency.

1 is an overall view showing a permanent magnet according to the present invention. It is the figure which showed the axial gap type motor by which the permanent magnet is arrange | positioned. It is the figure which showed the magnetization easy axis direction of the permanent magnet. It is the figure which showed the magnetization easy axis direction of the permanent magnet. It is the figure which showed the polar upward orientation of the plane upward formed by a ring-shaped permanent magnet. It is the figure which showed the modification of the axial gap type motor with which the permanent magnet is arrange | positioned. It is explanatory drawing which showed the manufacturing process of the rotary electric machine using the permanent magnet which concerns on this invention, and a permanent magnet. It is explanatory drawing which showed the formation process and magnetic field orientation process of the green sheet especially among the manufacturing processes of the permanent magnet which concerns on this invention. It is the figure which showed the permanent magnet created by laminating | stacking a green sheet, and the easy magnetization axis direction. It is the figure explaining the temperature rising aspect of the calcining process among the manufacturing processes of the permanent magnet which concerns on this invention. It is explanatory drawing which showed the manufacturing process of the rotary electric machine which concerns on this invention and used the permanent magnet and the permanent magnet.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a permanent magnet according to the present invention, a method for manufacturing the permanent magnet, a rotating electric machine using the permanent magnet, and an embodiment embodying the method for manufacturing the rotating electric machine will be described in detail with reference to the drawings.

[Configuration of permanent magnet]
First, the configuration of the permanent magnet 1 according to the present invention will be described. FIG. 1 is an overall view showing a permanent magnet 1 according to the present invention. As shown in FIG. 1, the permanent magnet 1 according to the present invention is an anisotropic ring magnet having an annular shape. As shown in FIG. 2, the axial gap type motor (or generator) 2 is arranged on the surface of the rotor 3 facing the stator 4 in particular, and constitutes the axial gap type motor (or generator) 2. . FIG. 2 is a view showing an axial gap type motor 2 in which a permanent magnet 1 is arranged. In the following embodiment, an example in which the permanent magnet 1 is an anisotropic ring magnet will be described. However, the shape (for example, the size of the diameter) and the number of poles of the permanent magnet 1 are formed as described later. The mode and orientation can be changed as appropriate.

  The permanent magnet 1 according to the present invention is made of an Nd—Fe—B based magnet. In addition, content of each component shall be Nd: 27-40 wt%, B: 0.8-2 wt%, Fe (electrolytic iron): 60-70 wt%. In order to improve magnetic properties, other elements such as Dy, Tb, Co, Cu, Al, Si, Ga, Nb, V, Pr, Mo, Zr, Ta, Ti, W, Ag, Bi, Zn, and Mg are added. May contain a small amount.

  Further, as shown in FIG. 1, the permanent magnet 1 is joined to each other by an adhesive (for example, a mixture of a resin and a solvent) made of a resin after a plurality of thin-plate fan-shaped sintered members 5 are combined into an annular shape. Then, it is constituted by being magnetized. Note that the sintered member 5 can be joined by a plasticizer or thermocompression bonding in addition to the adhesive. Further, the number of the sintered members 5 is a number corresponding to the number of poles of the permanent magnet 1. For example, when the number of poles of the permanent magnet 1 is eight, as shown in FIG. Consists of Note that a plurality of magnetic poles of the permanent magnet 1 are formed along the circumferential direction with respect to the ring-shaped axial surface (particularly, the surface facing the air gap when disposed in the motor 2).

  Furthermore, each sintered member 5 constituting the permanent magnet 1 is formed by a molded body (green molded body) obtained by molding a mixture obtained by mixing magnet powder and a binder as described later. In addition, the mixture is not directly formed into the thin-plate fan shape shown in FIG. 1, but once formed into a shape other than the thin-plate fan shape (for example, sheet shape, block shape, etc.), and then punching, cutting, deformation It is good also as a structure which makes it a thin-plate fan shape shape by processing etc. In particular, if the mixture is once formed into a sheet shape and then processed into a thin-plate fan shape, productivity can be improved by producing in a continuous process, and molding accuracy can also be improved. When making a mixture into a sheet shape, it is set as the thin film-like sheet member provided with thickness of 0.05 mm-10 mm (for example, 1 mm), for example. Even in the case of a sheet shape, a large permanent magnet 1 can be manufactured if a plurality of sheets are laminated.

  Further, the permanent magnet 1 according to the present invention is an anisotropic magnet, and as shown in FIG. 3, the sintered members 5 constituting the permanent magnet 1 are surfaces constituting a ring-shaped axial surface when combined. The easy magnetization axis (C axis) is oriented so as to converge in a direction along the focusing axis P that passes through. FIG. 3 is a schematic diagram showing the orientation direction of the easy magnetization axis in the cross section X, the cross section Y, and the cross section Z cut along the circumferential direction of the permanent magnet 1. In the cross section X, the cross section Y, and the cross section Z, although the circumferential length of the cross section of the sintered member 5 is different, the orientation direction of the easy magnetization axis is the same shape (that is, the direction along the focusing axis P in the center). Draw a shape that the easy axis of magnetization converges.

  The focusing axis P is set in parallel to the ring-shaped axial direction for each magnetic pole formed on the ring-shaped axial surface. That is, as shown in FIG. 3, when the permanent magnet 1 is composed of eight sintered members 5 and one magnetic pole is formed with respect to one sintered member 5, a focusing axis is provided for each sintered member 5. P is present, and the magnetized permanent magnet 1 has eight magnetic poles formed on the ring-shaped axial surface (see FIG. 5). Further, the focusing direction of the easy magnetization axis is the direction of the air gap side (the facing stator side when the permanent magnet 1 is arranged on the rotor) when the permanent magnet 1 is arranged on the rotor 3 of the motor 2. Become. As a result, the orientation of the ring-shaped permanent magnet 1 combined with the sintered member 5 has a polar anisotropy upward in the plane as will be described later.

  In the example shown in FIG. 3, the focusing axis P is set so as to pass near the center of the sintered member 5, but may be set not on the center but on the right side or the left side. Further, when the permanent magnet 1 is disposed on the rotor 3, as shown in FIG. 3, the easy axis of magnetization from the both end sides of the sintered member 5 to the center side and the air gap side along the circumferential direction of the rotor 3. Oriented so that (C axis) is inclined. More specifically, the easy magnetization axis is formed along an exponential curve. As a result, when the permanent magnet 1 is arranged on the rotor 3 and magnetized, the magnetic flux inside the magnet concentrates on the air gap side along the circumferential direction of the rotor 3 (that is, on the air gap side surface of the magnet). Magnetic flux density is increased).

  Further, as shown in FIG. 4, the easy magnetization axis may be oriented so as to converge linearly in one direction along the focusing axis P. Even in that case, the orientation of the permanent magnet 1 combined with the sintered member 5 has a polar anisotropy upward in the plane.

  Further, in the permanent magnet 1 according to the present invention, since the magnetic field is applied to the mixture of the magnet powder and the binder as will be described later, the magnetic particles are aligned by the pressure applied after the orientation as in compacting. It is possible to improve the degree of orientation without rotating. Moreover, since there is no variation in the density distribution of the magnet powder unlike the PLP method, the near net shape property is improved. Furthermore, a magnetic field is applied to the mixture before forming it into a product shape (for example, a thin-plate fan shape shown in FIG. 1), and after orientation, the mixture is formed in consideration of the direction of the easy axis of magnetization of the mixture. If (for example, deformation processing) is performed to form the product shape, the direction of the easy magnetization axis can be manipulated in the process of forming the product shape. That is, it is possible to properly orient the easy magnetization axis in the direction intended by the manufacturer. As a result, a permanent magnet having an easy axis oriented in a complicated direction (for example, an anisotropic ring magnet oriented so that the easy axis can be focused in a specific direction as shown in FIG. 3) can be easily and accurately realized. It becomes possible.

  In the magnetic field orientation with respect to the permanent magnet 1, as described above, a magnetic field is applied to the mixture before forming into a product shape (for example, a thin plate fan shape shown in FIG. 1), and then the orientation is performed. It is good also as a structure which performs the magnetic field orientation with respect to a molded object by shaping | molding, and may shape | align by applying a magnetic field after shape | molding to a product shape.

  3 and 4, when the permanent magnet 1 in which the sintered members 5 having the easy axis oriented are joined in an annular shape is magnetized along the direction of the easy axis, FIG. It is possible to realize a polar anisotropic orientation upward in the plane as shown in FIG. In addition, on the ring-shaped axial surface, S poles and N poles are alternately arranged corresponding to the number of sintered members 5 (that is, the number of focusing axes P) along the circumferential direction. Further, a sinusoidal magnetic flux density distribution can be obtained for the magnetic flux density distribution in the circumferential direction of the axial surface. In an axial gap type rotating electrical machine having a permanent magnet with an anisotropic orientation facing upward in a plane, the torque and power generation amount of the rotating electrical machine are improved, and further, torque ripple is limited to accurately control the driving of the rotating electrical machine. There are merits that can be done. Further, by bringing the waveform of the magnetic flux density distribution in the circumferential direction of the surface in the axial direction of the permanent magnet 1 (that is, the magnetic flux density distribution in the air gap of the rotating electrical machine) closer to an ideal sine wave shape, torque ripple is further reduced. It is possible to realize noise reduction and vibration reduction of the rotating electrical machine.

（但し、Ｒ１及びＲ２は、水素原子、低級アルキル基、フェニル基又はビニル基を表す） In the present invention, in particular, when the permanent magnet 1 is manufactured, a resin, a long-chain hydrocarbon, a fatty acid ester, a mixture thereof, or the like is used as the binder mixed with the magnet powder.
Furthermore, when a resin is used for the binder, it is preferable to use a polymer that does not contain an oxygen atom in the structure and has a depolymerization property. In addition, as described later, in order to reuse the mixture residue generated when the mixture of the magnet powder and the binder is formed into a desired shape (for example, a thin-plate fan shape), and in a state where the mixture is softened by heating. A thermoplastic resin is used to perform magnetic field orientation. Specifically, the polymer which consists of 1 type, or 2 or more types of polymers or copolymers chosen from the monomer shown by the following general formula (1) corresponds.

(However, R1 and R2 represent a hydrogen atom, a lower alkyl group, a phenyl group or a vinyl group.)

Examples of the polymer satisfying the above conditions include polyisobutylene (PIB), which is a polymer of isobutylene, polyisoprene (isoprene rubber, IR), which is a polymer of isoprene, and polybutadiene (butadiene) that is a polymer of 1,3-butadiene. Rubber, BR), polystyrene as a polymer of styrene, styrene-isoprene block copolymer (SIS) as a copolymer of styrene and isoprene, butyl rubber (IIR) as a copolymer of isobutylene and isoprene, styrene and butadiene A styrene-butadiene block copolymer (SBS) which is a copolymer of 2-methyl-1-pentene, a 2-methyl-1-pentene polymer which is a polymer of 2-methyl-1-pentene, and a polymer of 2-methyl-1-butene. A 2-methyl-1-butene polymer, a polymer of α-methylstyrene. That there is α- methyl styrene polymer resin. In addition, it is desirable to add a low molecular weight polyisobutylene to the α-methylstyrene polymer resin in order to give flexibility. The resin used for the binder may include a small amount of a polymer or copolymer of a monomer containing an oxygen atom (for example, polybutyl methacrylate, polymethyl methacrylate, etc.). Furthermore, a monomer that does not correspond to the general formula (1) may be partially copolymerized. Even in that case, it is possible to achieve the object of the present invention.
In addition, as a resin used for the binder, a thermoplastic resin that softens at 250 ° C. or lower in order to appropriately perform magnetic field orientation, more specifically, a thermoplastic resin having a glass transition point or a flow start temperature of 250 ° C. or lower is used. Is desirable.

  On the other hand, when a long-chain hydrocarbon is used as the binder, it is preferable to use a long-chain saturated hydrocarbon (long-chain alkane) that is solid at room temperature and liquid at room temperature or higher. Specifically, it is preferable to use a long-chain saturated hydrocarbon having 18 or more carbon atoms. Then, when the mixture of the magnetic powder and the binder is magnetically oriented as described later, the magnetic field orientation is performed in a state where the mixture is heated and softened at a temperature equal to or higher than the glass transition point of the long-chain hydrocarbon or the flow start temperature.

  Similarly, when a fatty acid ester is used as the binder, it is preferable to use methyl stearate, methyl docosanoate or the like that is solid at room temperature and liquid at room temperature or higher. Then, when the mixture of the magnet powder and the binder is magnetically oriented as described later, the magnetic field orientation is performed in a state where the mixture is heated and softened at a temperature equal to or higher than the flow start temperature of the fatty acid ester.

  By using a binder that satisfies the above conditions as a binder to be mixed with the magnet powder, the amount of carbon and oxygen contained in the magnet can be reduced. Specifically, the amount of carbon remaining in the magnet after sintering is 2000 ppm or less, more preferably 1000 ppm or less. Further, the amount of oxygen remaining in the magnet after sintering is set to 5000 ppm or less, more preferably 2000 ppm or less.

  Further, the amount of the binder added is an amount that appropriately fills the gaps between the magnet particles in order to improve the thickness accuracy of the molded body when molding the slurry or the heated and melted compound. For example, the ratio of the binder to the total amount of the magnet powder and the binder is 1 wt% to 40 wt%, more preferably 2 wt% to 30 wt%, and still more preferably 3 wt% to 20 wt%.

[Configuration of rotating electric machine]
Further, the axial gap type motor 2 in which the permanent magnet 1 is disposed on the rotor 3 includes a stator 4 and a rotor disposed to face the stator 4 with an air gap 6 at a predetermined interval as shown in FIG. 3 and an output shaft 7 having one end fixed to the rotor 3 and supported rotatably with respect to the stator 4.

  The stator 4 basically includes a stator core 8 made of a magnetic material such as an electromagnetic steel plate and a plurality of windings 9 wound around the stator core 8. Further, the stator core 8 includes an annular yoke and a plurality of teeth protruding in the axial direction from the yoke, and the winding 9 is wound around the teeth. In addition, in order to implement | achieve a thin-plate shape, it may replace with the stator core 8 and the coil | winding 9, and may use the printed circuit board by which the air-core coil is arrange | positioned.

  In addition, an output shaft 7 that is rotatably supported with respect to the stator 4 is provided at the center of the stator 4. The output shaft 7 is connected to the rotor 3 and is configured to rotate with the rotation of the rotor 3 when the rotor 3 rotates.

  On the other hand, the rotor 3 is provided with the ring-shaped permanent magnet 1 on the surface facing the air gap 6 as described above. Further, a back yoke for constituting a magnetic path is also arranged on the back surface of the permanent magnet 1. The permanent magnet 1 is magnetized so that the S pole and the N pole are alternately arranged along the circumferential direction, and is arranged to face the stator 4 with a predetermined interval. Further, as shown in FIGS. 3 and 4, the magnetic flux inside the magnet is concentrated toward the air gap 6 along the circumferential direction of the rotor 3.

  In such a configuration, when a current is applied to the winding 9 of the stator 4, a magnetic attractive force and a repulsive force are generated between the rotor 3 and the stator 4, and the rotor 3 rotates about the output shaft 7. . In particular, in the present invention, a high torque can be obtained by configuring the magnetic flux inside the magnet to concentrate toward the air gap 6 along the circumferential direction of the rotor 3.

Further, the axial gap type motor 2 in which the permanent magnet 1 is arranged may have the configuration shown in FIG. Specifically, the stator 4 is installed vertically symmetrically in the axial direction, and the rotor 3 on which the permanent magnets 1 are arranged is arranged at two locations on the upper and lower sides facing each stator 4. Even in that case, high torque can be obtained by configuring the permanent magnets 1 arranged in the upper and lower rotors 3 so that the magnetic flux inside the magnets is concentrated on the air gap 6 side.
Further, by adopting the above configuration, the attractive force generated between the permanent magnet 1 and the stator 4 can be offset, and the mechanical stability of the motor 2 can be ensured. Furthermore, if the configuration shown in FIG. 6 is repeated in the axial direction, the torque of the motor 2 can be further improved.

  Note that the positional relationship between the stator 4 and the rotor 3 of the motor 2 shown in FIG. 6 may be interchanged. That is, the rotor 3 in which the permanent magnets 1 are respectively disposed on the upper and lower surfaces may be installed in the center, and the stator 4 may be disposed at two positions on the upper and lower sides of the rotor 3 so as to face the upper and lower surfaces of the rotor 3.

[Permanent magnet and method of manufacturing rotating electrical machine using permanent magnet]
Next, the manufacturing method of the rotary electric machine using the permanent magnet 1 and the permanent magnet 1 which concerns on this invention is demonstrated using FIG. FIG. 7 is an explanatory view showing a manufacturing process of the rotating electric machine using the permanent magnet 1 and the permanent magnet 1 according to the present embodiment.

  First, an ingot made of a predetermined fraction of Nd—Fe—B (for example, Nd: 32.7 wt%, Fe (electrolytic iron): 65.96 wt%, B: 1.34 wt%) is manufactured. Thereafter, the ingot is roughly pulverized to a size of about 200 μm by a stamp mill or a crusher. Alternatively, the ingot is melted, flakes are produced by strip casting, and coarsely pulverized by hydrogen crushing. Thereby, coarsely pulverized magnet powder 15 is obtained.

  Next, the coarsely pulverized magnet powder 15 is finely pulverized by a wet method using a bead mill 16 or a dry method using a jet mill. For example, in fine pulverization using a wet method using a bead mill 16, the coarsely pulverized magnet powder 15 is finely pulverized in a solvent to a predetermined particle size (for example, 0.1 μm to 5.0 μm) and the magnet powder is dispersed in the solvent. . Thereafter, the magnet powder contained in the solvent after the wet pulverization is dried by vacuum drying or the like, and the dried magnet powder is taken out. Moreover, there is no restriction | limiting in particular in the kind of solvent used for grinding | pulverization, Alcohols, such as isopropyl alcohol, ethanol, methanol, Esters, such as ethyl acetate, Lower hydrocarbons, such as pentane and hexane, Aromatics, such as benzene, toluene, xylene , Ketones, mixtures thereof and the like. In addition, Preferably, the solvent which does not contain an oxygen atom in a solvent is used.

  On the other hand, in fine pulverization using a dry method using a jet mill, coarsely pulverized magnet powder is (a) in an atmosphere composed of an inert gas such as nitrogen gas, Ar gas, and He gas having substantially 0% oxygen content. Or (b) Finely pulverizing by a jet mill in an atmosphere made of an inert gas such as nitrogen gas, Ar gas, and He gas with an oxygen content of 0.0001 to 0.5%, A fine powder having an average particle diameter of 0.7 μm to 5.0 μm. The oxygen concentration of substantially 0% is not limited to the case where the oxygen concentration is completely 0%, but may contain oxygen in such an amount that a very small amount of oxide film is formed on the surface of the fine powder. Means good.

  Next, the magnet powder finely pulverized by the bead mill 16 or the like is molded into a desired shape. The magnet powder is molded by molding a mixture of magnet powder and binder. In the following examples, a magnetic field is applied by applying a magnetic field in a state where the mixture is once formed in a shape other than the product shape, and then the product shape (for example, as shown in FIG. 1) is performed by punching, cutting, deformation, or the like. Thin plate fan shape). In particular, in the following examples, the mixture is once formed into a sheet-shaped green molded body (hereinafter referred to as a green sheet) to obtain a product shape. In addition, when the mixture is formed into a sheet shape, for example, hot melt coating that forms a sheet shape after heating a compound in which a magnet powder and a binder are mixed, or a slurry containing a magnet powder, a binder, and an organic solvent. There is molding by slurry coating or the like to form a sheet by coating the substrate on a substrate.

Hereinafter, green sheet forming using hot melt coating will be described.
First, a clay-like mixture (compound) 17 composed of magnet powder and binder is prepared by mixing a binder with magnet powder finely pulverized by a bead mill 16 or the like. Here, as the binder, a resin, a long-chain hydrocarbon, a fatty acid ester, a mixture thereof, or the like is used as described above. For example, when a resin is used, a thermoplastic resin made of a depolymerizable polymer that does not contain an oxygen atom in the structure is used. On the other hand, when a long-chain hydrocarbon is used, the resin is solid at room temperature or above room temperature. It is preferable to use a long-chain saturated hydrocarbon (long-chain alkane) that is liquid. Moreover, when using fatty acid ester, it is preferable to use methyl stearate, methyl docosanoate, or the like. In addition, as described above, the amount of the binder added is such that the ratio of the binder to the total amount of the magnet powder and the binder in the compound 17 after the addition is 1 wt% to 40 wt%, more preferably 2 wt% to 30 wt%, still more preferably 3 wt%. % To 20 wt%.

  In addition, an additive for promoting orientation may be added to the compound 17 in order to improve the degree of orientation in a magnetic field orientation step performed later. As the additive for promoting the orientation, for example, a hydrocarbon-based additive is used, and it is particularly preferable to use an additive having polarity (specifically, an acid dissociation constant pKa of less than 41). Moreover, the addition amount of the additive depends on the particle diameter of the magnet powder, and it is necessary to increase the addition amount as the particle diameter of the magnet powder is smaller. The specific addition amount is 0.1 part to 10 parts, more preferably 1 part to 8 parts, with respect to the magnet powder. The additive added to the magnet powder adheres to the surface of the magnet particles and has a role of assisting the rotation of the magnet particles in the magnetic field orientation process described later. As a result, orientation is easily performed when a magnetic field is applied, and the easy magnetization axis directions of the magnet particles can be aligned in the same direction (that is, the degree of orientation can be increased). In particular, when a binder is added to the magnet powder, since the binder is present on the particle surface, the frictional force at the time of orientation is increased and the orientation of the particles is lowered, so that the effect of adding the additive is further increased.

  The binder is added in an atmosphere made of an inert gas such as nitrogen gas, Ar gas, or He gas. The mixing of the magnet powder and the binder is performed, for example, by putting the magnet powder and the binder into a stirrer and stirring with the stirrer. In addition, heating and stirring may be performed to promote kneading properties. The mixing of the magnet powder and the binder is preferably performed in an atmosphere made of an inert gas such as nitrogen gas, Ar gas, or He gas. In particular, when the magnet powder is pulverized by a wet method, a binder is added to the solvent without kneading the magnet powder from the solvent used for pulverization, and then the solvent is volatilized. It is good also as a structure to obtain.

  Subsequently, a green sheet is created by forming the compound 17 into a sheet shape. In particular, in the hot melt coating, the compound 17 is heated to melt the compound 17 to form a fluid, and then applied onto the support substrate 18 such as a separator. Thereafter, a long sheet-like green sheet 19 is formed on the support substrate 18 by heat radiation and solidification. The temperature at which the compound 17 is heated and melted varies depending on the type and amount of the binder used, but is 50 to 300 ° C. However, the temperature needs to be higher than the flow start temperature of the binder to be used. When slurry coating is used, magnet powder and binder (additional additives may be added) are dispersed in a large amount of solvent, and the slurry is coated on a support substrate 18 such as a separator. Work. Thereafter, the long sheet-like green sheet 19 is formed on the support substrate 18 by drying and volatilizing the solvent.

  Here, as a coating method of the melted compound 17, it is preferable to use a method having excellent layer thickness controllability such as a slot die method and a calendar roll method. In particular, in order to achieve high thickness accuracy, a die method or comma coating method that is particularly excellent in layer thickness controllability (that is, a method capable of applying a high-accuracy thickness layer on the surface of a substrate). It is desirable to use For example, in the slot die method, coating is performed by extruding a heated compound 17 in a fluid state by a gear pump and inserting the compound 17 into a die. In the calendar roll method, a certain amount of the compound 17 is charged in the gap between the two heated rolls, and the compound 17 melted by the heat of the roll is applied onto the support substrate 18 while rotating the roll. Moreover, as the support base material 18, for example, a silicone-treated polyester film is used. Furthermore, it is preferable to sufficiently defoam the film so that bubbles do not remain in the spreading layer by using an antifoaming agent or performing heating vacuum defoaming. Further, the green sheet is formed on the support substrate 18 by forming the compound 17 melted by extrusion molding or injection molding into a sheet shape and extruding the support substrate 18 instead of coating on the support substrate 18. It is good also as a structure which shape | molds 19. FIG.

  Further, in the step of forming the green sheet 19 by the slot die method, it is desirable to actually measure the sheet thickness of the green sheet 19 after coating, and to feedback control the gap between the die 20 and the support base 18 based on the actually measured value. . Further, the fluctuation of the amount of the fluid compound 17 supplied to the die 20 is reduced as much as possible (for example, suppressed to fluctuation of ± 0.1% or less), and the fluctuation of the coating speed is further reduced as much as possible (for example, ± 0. It is desirable to suppress the fluctuation to 1% or less. Thereby, the thickness accuracy of the green sheet 19 can be further improved. The thickness accuracy of the formed green sheet 19 is within ± 10%, more preferably within ± 3%, and even more preferably within ± 1% with respect to the design value (for example, 1 mm). In the other calendar roll method, it is possible to control the transfer film thickness of the compound 17 to the support base 18 by similarly controlling the calendar conditions based on the actually measured values.

  The set thickness of the green sheet 19 is desirably set in the range of 0.05 mm to 20 mm. When the thickness is less than 0.05 mm, the productivity must be reduced because multiple layers must be stacked.

  Next, the magnetic field orientation of the green sheet 19 formed on the support base material 18 by the hot-melt coating described above is performed. Specifically, the green sheet 19 is first softened by heating the green sheet 19 that is continuously conveyed together with the support substrate 18. Specifically, the green sheet 19 is softened until the viscosity becomes 1 to 1500 Pa · s, more preferably 1 to 500 Pa · s. Thereby, the magnetic field orientation can be appropriately performed.

  In addition, although the temperature and time at the time of heating the green sheet 19 change with kinds and quantity of the binder to be used, they are 100-250 degreeC and 0.1 to 60 minutes, for example. However, in order to soften the green sheet 19, it is necessary to set the glass transition point of the binder to be used or a temperature higher than the flow start temperature. In addition, as a heating method for heating the green sheet 19, for example, there are a heating method using a hot plate and a heating method using a heat medium (silicone oil) as a heat source. Next, magnetic field orientation is performed by applying a magnetic field to the in-plane direction and the length direction of the green sheet 19 softened by heating. The strength of the applied magnetic field is 5000 [Oe] to 150,000 [Oe], preferably 10,000 [Oe] to 120,000 [Oe]. As a result, the C axis (easy magnetization axis) of the magnet crystal included in the green sheet 19 is oriented in one direction. It should be noted that the magnetic field may be applied in the in-plane direction and the width direction of the green sheet 19. Moreover, it is good also as a structure which applies a magnetic field with respect to the several green sheet 19 simultaneously.

  Furthermore, when applying a magnetic field to the green sheet 19, a step of applying a magnetic field at the same time as the heating step may be performed, or the magnetic field may be applied after the heating step and before the green sheet 19 solidifies. It is good also as performing the process to apply. Moreover, it is good also as a structure which magnetic field orientates before the green sheet 19 coated by hot-melt coating solidifies. In that case, the heating step is not necessary.

  Next, the heating process and the magnetic field orientation process of the green sheet 19 will be described in more detail with reference to FIG. FIG. 8 is a schematic diagram showing a heating process and a magnetic field orientation process of the green sheet 19. In the example shown in FIG. 8, an example in which the magnetic field orientation process is performed simultaneously with the heating process will be described.

  As shown in FIG. 8, heating and magnetic field orientation on the green sheet 19 coated by the above-described slot die method are performed on the long green sheet 19 that is continuously conveyed by a roll. That is, an apparatus for performing heating and magnetic field orientation is disposed on the downstream side of the coating apparatus (die or the like), and is performed by a process continuous with the above-described coating process.

Specifically, the solenoid 25 is disposed on the downstream side of the die 20 and the coating roll 22 so that the transported support base material 18 and the green sheet 19 pass through the solenoid 25. Further, the hot plate 26 is disposed in a pair above and below the green sheet 19 in the solenoid 25. Then, the green sheet 19 is heated by a pair of upper and lower hot plates 26 and an electric current is passed through the solenoid 25, so that the in-plane direction of the long green sheet 19 (that is, the sheet surface of the green sheet 19). A magnetic field in the longitudinal direction). Thereby, the continuously conveyed green sheet 19 is softened by heating, and a magnetic field is applied to the in-plane direction and the length direction of the softened green sheet 19 (in the direction of arrow 27 in FIG. 8). Appropriate and uniform magnetic field orientation can be realized. In particular, the surface of the green sheet 19 can be prevented from standing upright by setting the direction in which the magnetic field is applied to the in-plane direction.
Moreover, it is preferable that the heat dissipation and solidification of the green sheet 19 performed after the magnetic field orientation is performed in a transported state. Thereby, the manufacturing process can be made more efficient.

  When the magnetic field orientation is performed in the in-plane direction and the width direction of the green sheet 19, a pair of magnetic field coils are arranged on the left and right sides of the green sheet 19 conveyed instead of the solenoid 25. And it becomes possible to generate a magnetic field in the in-plane direction and the width direction of the long sheet-like green sheet 19 by passing a current through each magnetic field coil.

  Further, the magnetic field orientation can be set to a direction perpendicular to the surface of the green sheet 19. When the magnetic field orientation is performed in a direction perpendicular to the surface of the green sheet 19, for example, the magnetic field application device using a pole piece or the like is used. In the case where the magnetic field orientation direction is a direction perpendicular to the surface of the green sheet 19, it is preferable that the film is also laminated on the surface on the opposite side of the green sheet 19 where the support base material 18 is laminated. Thereby, it is possible to prevent the surface of the green sheet 19 from being inverted.

  Further, instead of the heating method using the hot plate 26 described above, a heating method using a heat medium (silicone oil) as a heat source may be used.

  Here, when the green sheet 19 is formed from a liquid material having high fluidity such as slurry by a general slot die method or doctor blade method without using hot melt molding, a magnetic field gradient is generated. When the green sheet 19 is carried in, the magnetic powder contained in the green sheet 19 is attracted toward the stronger magnetic field, and the liquid of the slurry forming the green sheet 19, that is, the thickness of the green sheet 19 is uneven. May occur. On the other hand, when the compound 17 is molded into the green sheet 19 by hot melt molding as in the present invention, the viscosity near room temperature reaches tens of thousands to hundreds of thousands Pa · s, and the magnetism when passing through the magnetic field gradient is reached. There is no powder slippage. Furthermore, the viscosity of the binder is lowered by being transported and heated in a uniform magnetic field, and uniform C-axis orientation is possible only by the rotational torque in the uniform magnetic field.

  Further, when the green sheet 19 is formed by a liquid material having a high fluidity such as a slurry containing an organic solvent by a general slot die method or doctor blade method without using hot melt molding, the thickness exceeds 1 mm. When an attempt is made to produce a sheet, foaming due to vaporization of the organic solvent contained in the slurry or the like at the time of drying becomes a problem. Further, if the drying time is prolonged to suppress foaming, the magnet powder is settled, and accordingly, the density distribution of the magnet powder is biased with respect to the direction of gravity, which causes warping after firing. Therefore, in the molding from the slurry, the upper limit value of the thickness is substantially regulated, so it is necessary to mold the green sheet with a thickness of 1 mm or less and then laminate it. However, in such a case, the entanglement between the binders becomes poor, and delamination occurs in the subsequent binder removal step (calcination process), which causes a decrease in C-axis (easy magnetization axis) orientation, that is, residual magnetic flux density ( Br) decreases. On the other hand, when the compound 17 is molded into the green sheet 19 by hot melt molding as in the present invention, since it does not contain an organic solvent, even when a sheet having a thickness exceeding 1 mm is prepared, Concerns are resolved. And since the binder is in a sufficiently entangled state, there is no possibility of delamination in the debinding process.

  When applying a magnetic field to a plurality of green sheets 19 at the same time, for example, a plurality of (for example, six) green sheets 19 are continuously conveyed, and the stacked green sheets 19 are moved through the solenoid 25. Configure to pass. As a result, productivity can be improved.

And after performing the magnetic field orientation of the green sheet 19 by the method shown in FIG. 8, the green sheet 19 is deformed by applying a load to the green sheet 19, and is formed into a product shape. Note that the direction of the easy magnetization axis is displaced by the above deformation so as to be the direction of the easy magnetization axis required for the final product. As a result, the direction of the easy magnetization axis can be manipulated so that the easy magnetization axis converges in the direction along the focusing axis P as shown in FIG. Before the green sheet 19 is deformed, the shape considering the final product shape and the direction of the easy axis required for the final product (that is, required for the final product when the green sheet 19 is transformed into the final product shape). A shape in which the direction of the easy magnetization axis can be realized) is punched in advance and then deformed.
Further, when manufacturing a magnet having a large shape, a plurality of green sheets 19 deformed in the same shape may be stacked and molded by being fixed to each other with a resin or the like. For example, when manufacturing the permanent magnet 1 oriented so that the easy magnetization axis (C axis) is focused in one direction along the focusing axis P as shown in FIG. 3, the in-plane direction as shown in FIG. The green sheets 19 aligned in a magnetic field are curved and laminated so that the cross section in the thickness direction has an arc shape. As a result, the orientation as shown in FIG. 3 can be realized. The green sheet 19 may be laminated after being deformed, or may be deformed after being laminated.

Moreover, you may perform magnetic field orientation and shaping | molding to a molded object with the following method.
First, a sheet-like green sheet 19 before being subjected to magnetic field orientation cut to an appropriate length is wound around a cylindrical mold. Then, a magnetic field is applied to the green sheet 19 wound around the mold from one direction facing the surface of the green sheet 19. As a result, the easy magnetization axes of the magnet particles included in the green sheet 19 are aligned in parallel along the direction in which the magnetic field is applied. Thereafter, the green sheet 19 is deformed by applying a load to form a product shape, and the direction of the easy magnetization axis is set so that the easy magnetization axis is focused in one direction along the focusing axis P by the deformation. to correct. For example, when the fan shape as shown in FIG. 3 is formed into a product shape, the green sheet 19 that is curved along the mold is linear, and a load is applied from the left and right in the width direction. Shape. As a result, along with the deformation of the green sheet 19, the direction of the easy axis of magnetization of the green sheet 19 is also corrected, and the orientation as shown in FIG. 3 can be realized. Note that only one green sheet 19 may be deformed, or a plurality of green sheets 19 may be deformed in a stacked state.
The shape of the green sheet 19 before being deformed by applying a load may be a shape other than a cylindrical shape. For example, it may be an arc shape, a fan shape, or a rectangular parallelepiped shape.

  Further, after forming a molded body corresponding to the product shape, a magnetic field may be applied to the molded body to perform magnetic field orientation. For example, one opening of the solenoid coil is disposed adjacent to the molded body, and a magnetic field formed by passing a current through the solenoid coil is applied to the molded body. In the vicinity of the opening of the solenoid coil, a magnetic field in which the magnetic lines of force diffuse in the left-right direction is formed. Therefore, the compact is oriented so that the easy axis (C axis) is focused in one direction along the focusing axis P as shown in FIG. Moreover, you may orient using a permanent magnet or an electromagnet instead of a solenoid coil. Furthermore, after shaping | molding a mixture into a ring shape, it is good also as a structure which applies a magnetic field to a molded object and performs magnetic field orientation.

  Subsequently, a non-oxidizing atmosphere (particularly hydrogen in the present invention) in which the molded body 30 that has been molded and magnetically oriented is pressurized to atmospheric pressure, or a pressure higher or lower than atmospheric pressure (for example, 1.0 Pa or 1.0 MPa). In the atmosphere or a mixed gas atmosphere of hydrogen and an inert gas), the calcination treatment is performed by maintaining the binder decomposition temperature for several hours to several tens of hours (for example, 5 hours). In the case of performing in a hydrogen atmosphere, for example, the supply amount of hydrogen during calcination is set to 5 L / min. By performing the calcination treatment, an organic compound such as a binder can be decomposed into a monomer by a depolymerization reaction or the like and scattered to be removed. That is, so-called decarbonization that reduces the amount of carbon in the molded body 30 is performed. The calcining treatment is performed under the condition that the carbon content in the molded body 30 is 2000 ppm or less, more preferably 1000 ppm or less. As a result, the entire molded body 30 can be densely sintered by the subsequent sintering treatment, and a decrease in residual magnetic flux density and coercive force is suppressed. Moreover, when performing the pressurization conditions at the time of performing the calcining process mentioned above by the pressure higher than atmospheric pressure, it is desirable to set it as 15 MPa or less. In addition, if the pressurizing condition is a pressure higher than atmospheric pressure, more specifically 0.2 MPa or more, the effect of reducing the carbon amount can be expected.

  The binder decomposition temperature is determined based on the analysis results of the binder decomposition product and decomposition residue. Specifically, a temperature range is selected in which decomposition products of the binder are collected, decomposition products other than the monomers are not generated, and products due to side reactions of the remaining binder components are not detected even in the analysis of the residues. Although it varies depending on the type of the binder, it is set to 200 ° C to 900 ° C, more preferably 400 ° C to 600 ° C (for example, 450 ° C).

  In the calcining process, it is preferable to reduce the rate of temperature rise compared to the case of performing general magnet sintering. Specifically, the temperature rising rate is set to 2 ° C./min or less (for example, 1.5 ° C./min). Therefore, when performing the calcining treatment, as shown in FIG. 10, the temperature is increased at a predetermined temperature increase rate of 2 ° C./min or less, and after reaching a preset temperature (binder decomposition temperature), The calcination treatment is performed by holding at the set temperature for several hours to several tens of hours. By reducing the temperature increase rate in the calcination treatment as described above, the carbon in the molded body 30 is not removed abruptly and is removed stepwise, thereby increasing the density of the sintered permanent magnet ( That is, it is possible to reduce the air gap in the permanent magnet. And if a temperature increase rate shall be 2 degrees C / min or less, the density of the permanent magnet after sintering can be made 95% or more, and a high magnet characteristic can be anticipated.

Moreover, you may perform a dehydrogenation process by hold | maintaining the molded object 30 calcined by the calcination process in a vacuum atmosphere continuously. Dehydrogenation process, a calcination process NdH 3 in the compact 30 produced by _(activity Univ), NdH 3 _(activity Univ) → NdH 2 by gradually changed to _(activity small) The activity of the molded body 30 activated by the calcination treatment is reduced. As a result, even if the compact 30 that has been calcined by the calcining process is subsequently moved to the atmosphere, Nd is prevented from being combined with oxygen, and a decrease in residual magnetic flux density and coercive force is suppressed. To do. Moreover, the effect of returning the structure of the magnet crystals from NdH ₂ etc. to _Nd 2 _{Fe 14} B structure can be expected.

  Then, the sintering process which sinters the molded object 30 calcined by the calcining process is performed. In addition, as a sintering method of the molded body 30, pressureless sintering in vacuum, uniaxial pressure sintering for sintering in a state pressurized in a uniaxial direction, sintering in a state in which pressure is applied in a biaxial direction There are two-axis pressure sintering, isotropic pressure sintering for sintering in an isotropically pressurized state, and the like. For example, uniaxial pressure sintering is used in which the compact 30 is sintered in a state in which the compact 30 is pressed in the same direction as the axial direction of the rotor 3 when the molded body 30 is disposed on the rotor 3 surface. Examples of pressure sintering include hot press sintering, hot isostatic pressing (HIP) sintering, ultra-high pressure synthetic sintering, gas pressure sintering, and discharge plasma (SPS) sintering. . However, it is preferable to use SPS sintering that can be uniaxially pressurized and sintered by current sintering. In addition, when sintering by SPS sintering, a pressurization value shall be 0.01MPa-100MPa, it shall be raised to 940 degreeC by 10 degreeC / min in a vacuum atmosphere of several Pa or less, and it shall hold | maintain for 5 minutes after that. Is preferred. Then, it is cooled and heat-treated again at 300 to 1000 ° C for 2 hours. And as a result of sintering, the sintered compact 31 is manufactured.

  Thereafter, the sintered body 31 formed into a thin plate fan shape by the above process and oriented so that the easy axis of magnetization is focused in one direction along the focusing axis P is joined in an annular shape. Thereby, a ring-shaped sintered body (hereinafter referred to as a ring sintered body 32) is produced. The ring sintered body 32 is joined by an adhesive, a plasticizer, and thermocompression bonding.

  Moreover, in the said Example, although it is set as the structure which produces the ring sintered compact 32 by joining the annular | circular shape after sintering the thin-plate fan-shaped molded object 30, the molded object 30 before performing a sintering process is used. It is good also as a structure which produces the ring sintered compact 32 by performing a sintering process after setting it as a ring-shaped molded object by joining to a ring shape.

  After that, as shown in FIG. 11, magnetization is performed along the C axis so as to have polar anisotropy upward in the plane. As a result, the permanent magnet 1 that is an anisotropic ring magnet can be manufactured. For magnetizing the permanent magnet 1, for example, a magnetizing coil, a magnetizing yoke, a condenser magnetizing power supply device or the like is used. The permanent magnet 1 may be magnetized after being arranged on the rotor 3 of the rotating electrical machine. Moreover, it is good also as a structure performed with respect to the sintered compact 31 before joining to annular | circular shape.

  Thereafter, the permanent magnet 1 is disposed on the rotor 3, and members other than the rotor 3 such as the stator 4 and the output shaft 7 are assembled to manufacture the axial gap type motor 2. The magnetized permanent magnet 1 can concentrate the magnetic flux inside the magnet toward the air gap along the circumferential direction of the rotor 3 (that is, increase the magnetic flux density on the magnet surface).

As described above, in the permanent magnet 1 and the method for manufacturing the permanent magnet 1 according to the present embodiment, the compound 17 is generated by pulverizing the magnet raw material into magnet powder and mixing the pulverized magnet powder and the binder. . And the green sheet 19 which shape | molded the produced | generated compound 17 in the sheet form is produced. Thereafter, magnetic field orientation is performed by applying a magnetic field to the molded green sheet 19, and the green sheet 19 is deformed while considering the magnetic field orientation direction of the magnetically oriented green sheet 19 to be molded into a product shape. . Then, the permanent magnet 1 is manufactured by sintering. In addition, the permanent magnet 1 has a ring shape, and the easy magnetization axis is inclined and oriented so as to focus in a direction along the focusing axis set parallel to the axial direction of the ring shape. On the surface in the axial direction, the magnetic flux can be appropriately concentrated after magnetization, and the maximum magnetic flux density can be improved and the variation of the magnetic flux density can be prevented. In particular, in an axial gap type rotating electrical machine, if the permanent magnet is disposed in the stator or rotor, the maximum magnetic flux density is improved by concentrating the magnetic flux on the air gap side, and the rotating electrical machine in which the permanent magnet is disposed. Torque and power generation can be improved and torque ripple can be reduced.
In addition, by forming a mixture of magnet powder and binder, the easy magnetization axis can be oriented so as to be properly focused in one direction along the focusing axis. As a result, it is possible to concentrate the magnetic flux appropriately after magnetization, thereby improving the maximum magnetic flux density and preventing variations in the magnetic flux density.
Further, since the mixture with the binder is molded, the magnet particles do not rotate after the orientation and the degree of orientation can be improved as compared with the case of using compacting or the like.
In addition, when magnetic field orientation is performed on a mixture with a binder, the number of current turns can be used, so that it is possible to ensure a large magnetic field strength when performing magnetic field orientation, and long-term magnetic field application with a static magnetic field. Therefore, it is possible to realize a high degree of orientation with little variation. If the orientation direction is corrected after the orientation, it is possible to secure a highly oriented orientation with little variation.
Furthermore, the realization of high orientation with little variation leads to a reduction in variation in shrinkage due to sintering. That is, the uniformity of the product shape after sintering can be ensured. As a result, it can be expected that the burden on the external processing after sintering is reduced and the stability of mass production is greatly improved.
Further, the torque ripple is reduced by bringing the waveform of the magnetic flux density distribution in the circumferential direction of the ring-shaped axial surface of the permanent magnet 1 closer to an ideal sine wave shape, and when the rotating magnet is installed in the rotating electrical machine, Drive control can be performed accurately.
Further, in the magnetic field orientation step, a magnetic field is applied to the mixture of the magnet powder and the binder, and the direction of the easy magnetization axis is manipulated by transforming the mixture to which the magnetic field has been applied into a molded body. Since the orientation is performed, it is possible to correct the orientation direction by deforming the magnetically oriented mixture, and to align the easy magnetization axis appropriately in one direction along the focusing axis. As a result, it is possible to perform a highly oriented orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected simultaneously with the deformation to the molded body. As a result, the molding process and the orientation process of the permanent magnet can be performed in one process, and the productivity can be improved.
In addition, since the mixture is once formed into a sheet shape, magnetic field orientation is performed, and then the molded body is deformed. Therefore, the molding process and the magnetic field orientation process can be performed efficiently in a continuous process, improving productivity. It becomes possible to make it.
Further, since the easy magnetization axis is inclined to the air gap side along the circumferential direction of the rotor 3 of the axial gap type rotating electrical machine, the magnetic flux is more concentrated to the air gap side when the rotor 3 is arranged and magnetized. It becomes possible to make it. As a result, it is possible to improve the torque and power generation amount of the rotating electrical machine in which the permanent magnet is arranged.
Further, when the magnet is disposed and magnetized in the rotor 3 of the axial gap type rotating electrical machine, the magnetic flux inside the magnet is concentrated on the air gap side, so that the torque and power generation amount of the rotating electrical machine where the permanent magnet 1 is disposed. Can be improved.
Furthermore, in the axial gap type rotating electrical machine in which the permanent magnet 1 is disposed on the rotor 3, the power generation of the generator is improved, the torque of the motor is increased, the motor is reduced in size, the torque ripple is reduced, and the efficiency is increased. It can be realized.

In addition, this invention is not limited to the said Example, Of course, various improvement and deformation | transformation are possible within the range which does not deviate from the summary of this invention.
For example, the pulverization conditions, kneading conditions, molding conditions, magnetic field orientation process, calcination conditions, sintering conditions, etc. of the magnet powder are not limited to the conditions described in the above examples. For example, in the above embodiment, the magnet raw material is pulverized by wet pulverization using a bead mill, but may be pulverized by dry pulverization using a jet mill. Moreover, as long as the atmosphere at the time of calcination is a non-oxidizing atmosphere, the atmosphere may be other than a hydrogen atmosphere (for example, a nitrogen atmosphere, a He atmosphere, or an Ar atmosphere). Moreover, you may abbreviate | omit a calcination process. In that case, decarbonization is performed during the sintering process.

  Moreover, in the said Example, although it is set as the structure which performs magnetic field orientation after shape | molding the mixture of magnet powder and a binder once to a sheet-shaped green molded object, the structure which performs magnetic field orientation after shape | molding in shapes other than a sheet shape. It is also good. For example, it may be molded into a block-shaped green molded body. Then, the block-shaped green molded body aligned with the magnetic field is further processed to form a thin-plate fan-shaped molded body 30.

  Moreover, in the said Example, although it is set as the structure shape | molded in the thin-plate fan-shaped molded object 30 after performing magnetic field orientation with respect to the mixture of magnet powder and a binder, the thin-plate fan-shaped molded object 30 is set. Magnetic field orientation may be performed after molding into a thin film. Further, the orientation direction of the magnetic field is changed depending on the type of ring magnet to be finally manufactured.

  Further, in the above embodiment, the green sheet 19 is formed into a plurality of thin plate fan shapes and then joined to form a ring shape. However, the green sheet 19 is directly formed into a ring shape without forming the thin plate fan shape. You may comprise as follows. In that case, the green sheet 19 with magnetic field orientation may be formed into a ring shape by punching or the like, or the magnetic powder and binder mixture may be directly formed into a ring shape without forming a sheet shape and then the magnetic field orientation. You may do it.

  In the above embodiment, the orientation direction of the easy magnetization axis of the permanent magnet is designed so that the shape of the magnetic flux density distribution in the circumferential direction of the surface in the axial direction of the permanent magnet is a sine wave shape. It is also possible to design the orientation direction of the easy axis of the permanent magnet so as to have the shape of Note that the shape of the magnetic flux density distribution to be realized can be changed as appropriate according to the type and application of the permanent magnet.

  Further, the present invention can also be applied to a rotating electric machine in which a permanent magnet is arranged not on the rotor side but on the stator side. For example, if a permanent magnet is arranged in the stator of an axial gap type rotating electrical machine, the magnetic flux inside the magnet is concentrated on the rotor side arranged facing the stator. Furthermore, the permanent magnet according to the present invention can be applied to various rotating electric machines such as a generator and a magnetic speed reducer in addition to the motor. When the rotating electrical machine according to the present invention is applied to a magnetic speed reducer, the stator 4 is constituted by a predetermined number of magnetic pole pieces made of a magnetic material instead of the stator core 8 and the windings 9.

  Moreover, in the said Example, although it is set as the rotary electric machine which has the stator 4 which wound the winding 9 around the stator core 8, the stator core 8 may be comprised with a non-magnetic material other than a magnetic material. Further, the rotating electrical machine may be a coreless motor having no stator core. In that case, the stator 4 is formed by fixing the winding 9 in a cup shape with resin or the like. In such a coreless motor, iron loss can be eliminated, so that the efficiency of the rotating electrical machine can be increased.

  In the above embodiment, calcining is performed in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas after molding the magnet powder. However, the magnet powder before molding is calcined and calcined. It is good also as manufacturing a permanent magnet by shape | molding the magnetic powder which is a body into a molded object, and performing sintering after that. With such a configuration, since the powdered magnet particles are calcined, the surface area of the magnet to be calcined is increased compared to the case of calcining the molded magnet particles. can do. That is, the amount of carbon in the calcined body can be reduced more reliably. However, in order to thermally decompose the binder by calcining, it is desirable to perform calcining after molding.

  In the present invention, the Nd—Fe—B system magnet has been described as an example, but other magnets (for example, a samarium system cobalt magnet, an alnico magnet, a ferrite magnet, etc.) may be used. Further, in the present invention, the Nd component is larger than the stoichiometric composition in the present invention, but it may be stoichiometric.

DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Axial gap type motor 3 Rotor 4 Stator 5 Sintered member 17 Compound 19 Green sheet 30 Molded body 31 Sintered body 32 Ring sintered body

Claims (15)

Having a ring shape,
A plurality of magnetic poles are formed along the circumferential direction on the ring-shaped axial surface,
A permanent magnet, wherein each of the magnetic poles is oriented with an easy axis of magnetization inclined so as to focus in a direction along a focusing axis set in parallel to a ring-shaped axial direction.   The permanent magnet according to claim 1, wherein a shape of a magnetic flux density distribution in a circumferential direction of the surface in the axial direction is a sine wave shape. Crushing magnet raw material into magnet powder;
Producing a mixture in which the pulverized magnet powder and a binder are mixed;
Magnetic field orientation by applying a magnetic field to the mixture;
The permanent magnet according to claim 1 or 2, wherein the permanent magnet is sintered by holding a compact of the mixture oriented in a magnetic field at a firing temperature.   In the step of orienting the magnetic field, a magnetic field is applied to the mixture, and the direction of the easy axis is manipulated by transforming the mixture to which the magnetic field is applied into the compact. The permanent magnet according to claim 3.   5. The permanent magnet according to claim 4, wherein in the magnetic field orientation step, a magnetic field is applied to the sheet-like mixture after the mixture is formed into a sheet shape. The permanent magnet is arranged in a stator or rotor of an axial gap type rotating electrical machine,
The permanent magnet according to any one of claims 1 to 5, wherein an easy magnetization axis is inclined toward the air gap side along a circumferential direction of the stator or the rotor.   The permanent magnet according to claim 6, wherein when the magnet is arranged and magnetized in a stator or a rotor of the rotating electrical machine, a magnetic flux inside the magnet is concentrated on the air gap side.   An axial gap type rotating electrical machine, wherein the permanent magnet according to any one of claims 1 to 7 is disposed in a stator or a rotor. A method for producing a permanent magnet having a ring shape in which a plurality of magnetic poles are formed along a circumferential direction on an axial surface,
Crushing magnet raw material into magnet powder;
Producing a mixture in which the pulverized magnet powder and a binder are mixed;
Magnetic field orientation by applying a magnetic field to the mixture;
Sintering by holding the compact of the mixture oriented in a magnetic field at a firing temperature,
In the magnetic field orientation step,
A method of manufacturing a permanent magnet, characterized in that, for each of the magnetic poles, an easy magnetization axis is inclined and oriented so as to converge in a direction along a converging axis set parallel to an axial direction of a ring shape.   10. The permanent magnet according to claim 9, wherein in the magnetic field orientation step, the permanent magnet is oriented so that a shape of a magnetic flux density distribution in a circumferential direction of the axial surface of the manufactured permanent magnet is a sinusoidal shape. Manufacturing method.   In the step of orienting the magnetic field, a magnetic field is applied to the mixture, and the direction of the easy axis is manipulated by transforming the mixture to which the magnetic field is applied into the compact. The manufacturing method of the permanent magnet of Claim 9 or Claim 10 characterized by these.   The method of manufacturing a permanent magnet according to claim 11, wherein in the magnetic field orientation step, the magnetic field is applied to the sheet-like mixture after the mixture is formed into a sheet shape. The permanent magnet is arranged in a stator or rotor of an axial gap type rotating electrical machine,
The manufacture of a permanent magnet according to any one of claims 9 to 12, wherein an easy axis of magnetization is inclined toward the air gap along a circumferential direction of the stator or the rotor. Method.   14. The method of manufacturing a permanent magnet according to claim 13, wherein the magnetic flux inside the magnet is concentrated on the air gap side when the magnet is arranged and magnetized in the stator or rotor of the rotating electrical machine.   A manufacturing method of an axial gap type rotating electrical machine, wherein the permanent magnet manufactured by the manufacturing method according to claim 9 is disposed on a stator or a rotor.

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