JP6638051B2 - Permanent magnet for rotating electric machine, method for producing permanent magnet for rotating electric machine, rotating electric machine, and method for producing rotating electric machine - Google Patents

Description

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

  2. Description of the Related Art In recent years, machine tools, vehicles, aircraft, wind power motors, and the like have a generator that converts mechanical kinetic energy transmitted from an engine or the like into electric energy, and a motor that converts electric energy into mechanical kinetic energy ( A rotating electric machine such as an electric motor is generally used.

  Here, as a method of manufacturing a permanent magnet used for a rotating electric machine, a powder sintering method is generally used conventionally. Here, in the powder sintering method, first, magnet powder is produced by pulverizing raw materials by a jet mill (dry pulverization) or the like. Thereafter, the magnet powder is put into a mold and pressed into a desired shape. Then, it is manufactured by sintering a solid magnet powder formed into a desired shape at a predetermined temperature (for example, 1100 ° C. for an Nd—Fe—B magnet) (for example, JP-A-2-266503). In general, in a permanent magnet, a magnetic field orientation is performed by applying a magnetic field from the outside in order to improve magnetic characteristics. In a conventional method of manufacturing a permanent magnet by powder sintering, a mold is filled with magnet powder during press molding, a magnetic field is applied to orient the magnetic field, and then pressure is applied to form a compacted compact. Was. Further, in other methods for manufacturing a permanent magnet by an extrusion molding method, an injection molding method, a rolling molding method, or the like, the magnet is molded by applying pressure in an atmosphere to which a magnetic field is applied. This makes it possible to form a compact in which the direction of the axis of easy magnetization (C-axis) of each magnet particle constituting the permanent magnet is aligned with the direction of application of the magnetic field.

  Here, methods for aligning the easy axis of magnetization of the anisotropic magnet include axial anisotropy, radial anisotropy, and polar anisotropy. When an anisotropic magnet is used in a rotating electric machine, the easy axes of the magnet particles are not oriented in the same direction (that is, in parallel), but with the aim of reducing torque ripple and improving driving force. Orientation has also been performed to converge the axis of easy magnetization (for example, JP-A-2005-287181).

JP-A-2-266503 (page 5) JP 2005-287181 A (page 5, FIG. 2)

  Here, the permanent magnet conventionally arranged in the rotating electric machine has a problem that the magnetic flux gradually decreases, that is, demagnetizes, as the rotating electric machine is used. Then, when the demagnetization proceeds, the torque and the power generation amount of the rotating electric machine decrease. The reasons for the demagnetization include, for example, the occurrence of a demagnetizing field due to short-circuiting of magnetic flux lines and the shape and arrangement of magnets. Such demagnetization does not occur uniformly in the entire permanent magnet, but is particularly likely to occur in some areas.

  The present invention has been made in order to solve the above-described conventional problems.By concentrating magnetic flux in an area where demagnetization is likely to occur, it is possible to maintain a necessary and sufficient surface magnetic flux density even if demagnetization occurs. A method for manufacturing a permanent magnet for a rotating electrical machine, a method for manufacturing a permanent magnet for a rotating electrical machine, a method for manufacturing a rotating electrical machine using the permanent magnet for a rotating electrical machine, and a method for manufacturing the rotating electrical machine, which makes it possible to prevent the torque and power generation amount of the rotating electrical machine from being reduced. The purpose is to provide.

To achieve the above object, a permanent magnet for a rotating electrical machine according to claim 1 of the present application is a permanent magnet disposed on a rotor or a stator of the rotating electrical machine , and includes a focusing target area located at an end in a circumferential direction, and a circumferential direction. And a non-focusing target area located at the center of the target area. In the focusing target area, the demagnetization is located at a circumferential end located in the focusing target area and easily demagnetized compared to other areas. The easy axis of magnetization is oriented so as to focus on the target area, and the focus target area and the non-focus target area are integrated .

The permanent magnet rotating electric machine according to claim 2 is the permanent magnet rotating electric machine according to claim 1, the easy magnetization axis in the radial direction or parallel direction for the unfocused target area is oriented It is characterized by the following.

A permanent magnet for a rotating electrical machine according to claim 3 is the permanent magnet for a rotating electrical machine according to claim 1 or 2 , wherein a step of grinding a magnet raw material into magnet powder; Generating a mixture in which the mixture is mixed with a binder; and applying a magnetic field to the mixture to perform magnetic field orientation; and sintering by maintaining the molded body of the magnetically oriented mixture at a firing temperature. And a manufacturing step.

The permanent magnet for a rotating electrical machine according to claim 4 is the permanent magnet for a rotating electrical machine according to claim 3 , wherein in the step of orienting the magnetic field, a magnetic field is applied to the mixture and a magnetic field is applied. The orientation of the magnetic field is performed by operating the direction of the axis of easy magnetization by deforming the mixture thus formed into the compact.

The permanent magnet for a rotating electrical machine according to claim 5 is the permanent magnet for a rotating electrical machine according to claim 4 , wherein in the step of orienting the magnetic field, after the mixture is formed into a sheet, the sheet-like permanent magnet is formed. A magnetic field is applied to the mixture.

A rotating electric machine according to a sixth aspect is characterized in that the permanent magnet for the rotating electric machine according to any one of the first to fifth aspects is arranged on a rotor or a stator.

A method for manufacturing a permanent magnet for a rotating electric machine according to claim 7 is a method for manufacturing a permanent magnet disposed on a rotor or a stator of the rotating electric machine, wherein a step of pulverizing a magnet raw material into magnet powder; Generating a mixture in which the magnet powder and the binder are mixed, applying a magnetic field to the mixture, orienting the mixture in a magnetic field, and maintaining a compact of the mixture in the magnetic field at a firing temperature. In the step of sintering, and in the step of orienting the magnetic field , of the focusing target area located at the circumferential end provided by the permanent magnet and the non-focusing target area located at the center in the circumferential direction , in the said focusing target area to orient the easy axis to focus to demagnetization target area located at the end of the demagnetization is likely circumferential direction compared to other areas on the focused object area, the A bundle target area and the unfocused area of interest is equal to or formed integrally.

The method for manufacturing a permanent magnet for a rotating electrical machine according to claim 8 is the method for manufacturing a permanent magnet for a rotating electrical machine according to claim 7 , wherein in the step of magnetic field orientation, the non-focusing target area is radially oriented. The easy axis is oriented in a direction or a parallel direction.

A method for manufacturing a permanent magnet for a rotating electrical machine according to claim 9 is the method for manufacturing a permanent magnet for a rotating electrical machine according to claim 7 or claim 8 , wherein the step of orienting the magnetic field comprises: And applying a magnetic field by deforming the mixture to which the magnetic field has been applied into the compact to thereby control the direction of the axis of easy magnetization to perform magnetic field orientation.

A method for manufacturing a permanent magnet for a rotating electrical machine according to claim 10 is the method for manufacturing a permanent magnet for a rotating electrical machine according to claim 9 , wherein in the step of magnetic field orientation, the mixture is formed into a sheet. Later, a magnetic field is applied to the sheet-like mixture.

Furthermore, a manufacturing method of a rotating electric machine according to claim 11 is a method for producing a rotary electric machine, the permanent magnet rotating electric machine which is manufactured by any of the manufacturing method of claims 7 to 10 to the rotor or stator It is characterized by being manufactured by arranging.

  According to the permanent magnet for a rotating electrical machine according to claim 1 having the above-described configuration, the magnetic flux can be concentrated on an area that is easily demagnetized by controlling the orientation direction of the axis of easy magnetization, and demagnetization occurs. Even if necessary, it is possible to maintain a necessary and sufficient surface magnetic flux density. As a result, it is possible to prevent the torque and the power generation amount of the rotating electric machine from gradually decreasing with the use of the rotating electric machine. In addition, if the demagnetization resistance can be increased, the magnet volume can be reduced while maintaining the required demagnetization resistance, so that the downsizing of the permanent magnet and the reduction of the manufacturing cost can be realized. For example, the balance between the performance of the permanent magnet and the manufacturing cost can be kept optimal by reducing the magnet volume to the lower limit that can ensure the required demagnetization resistance.

Further, according to the permanent magnet rotating electric machine according to claim 1, instead of the entire permanent magnet, only the magnetization easy to focus into demagnetization target area as the target part of the area including the demagnetization target area Since the axes are oriented, the magnetic flux density in the area to be demagnetized can be increased, but the adverse effects of focusing the easy magnetization axis (for example, a decrease in the magnetic flux density in an area far from the area to be demagnetized). It can be eliminated.

Further, according to the permanent magnet rotating electric machine according to claim 2, with the exception of the area of the part where the easy magnetization axis is oriented so as to focus to the demagnetization target area, easily magnetized in the radial direction and parallel direction Since the axis is oriented, it is possible to realize an appropriate orientation according to the type of the rotating electric machine using the permanent magnet.

According to the permanent magnet for a rotating electrical machine of the third aspect , by forming a mixture of the magnet powder and the binder, the easy axis of magnetization is appropriately focused on the demagnetization target area. Orientation is possible. As a result, it is possible to appropriately concentrate the magnetic flux after the magnetization, and it is possible to secure the demagnetization resistance and prevent the variation in the magnetic flux density.
In addition, 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 powder compacting or the like.
When the magnetic field orientation is performed on the mixture with the binder, the number of turns of the current can be used, so that a large magnetic field strength can be secured when the magnetic field orientation is performed. , It is possible to realize a high degree of orientation with little variation. Then, if the orientation direction is corrected after the orientation, it is possible to secure a high orientation and an orientation with little variation.
Further, realization of high orientation with little variation leads to reduction in variation in shrinkage due to sintering. That is, uniformity of the product shape after sintering can be secured. As a result, it is 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 for a rotating electric machine according to the fourth aspect , the orientation direction is corrected by deforming the magnetic field-oriented mixture once so that the easy axis of magnetization is appropriately focused on the demagnetization target area. Orientation can be achieved. As a result, it is possible to perform high orientation and orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected while deforming the molded body. As a result, the molding step and the orientation step of the permanent magnet can be performed in one step, and the productivity can be improved.

According to the permanent magnet for a rotating electric machine according to the fifth aspect , the mixture is once formed into a sheet and then subjected to magnetic field orientation, and then deformed into a molded body. It can be performed efficiently in the process, and the productivity can be improved.

Further, according to the rotating electric machine of the sixth aspect , it is possible to prevent a decrease in torque and power generation even if demagnetization occurs in a permanent magnet arranged in the rotating electric machine.

According to the method for manufacturing a permanent magnet for a rotating electric machine according to the seventh aspect , the magnetic flux can be concentrated on an area that is easily demagnetized by controlling the orientation direction of the axis of easy magnetization. Even if demagnetization occurs in the permanent magnet, it is possible to maintain a necessary and sufficient surface magnetic flux density. As a result, it is possible to prevent the torque and the power generation amount of the rotating electric machine from gradually decreasing with the use of the rotating electric machine. In addition, if the demagnetization resistance can be increased, the magnet volume can be reduced while maintaining the required demagnetization resistance, so that the downsizing of the permanent magnet and the reduction of the manufacturing cost can be realized. For example, the balance between the performance of the permanent magnet and the manufacturing cost can be kept optimal by reducing the magnet volume to the lower limit that can ensure the required demagnetization resistance.
In addition, by forming a mixture of the magnet powder and the binder, it is possible to orient the magnetization easy axis appropriately to focus on the demagnetization target area. As a result, it is possible to appropriately concentrate the magnetic flux after the magnetization, and it is possible to secure the demagnetization resistance and prevent the variation in the magnetic flux density.
In addition, 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 powder compacting or the like.
When the magnetic field orientation is performed on the mixture with the binder, the number of turns of the current can be used, so that a large magnetic field strength can be secured when the magnetic field orientation is performed. , It is possible to realize a high degree of orientation with little variation. Then, if the orientation direction is corrected after the orientation, it is possible to secure a high orientation and an orientation with little variation.
Further, realization of high orientation with little variation leads to reduction in variation in shrinkage due to sintering. That is, uniformity of the product shape after sintering can be secured. As a result, it is expected that the burden on the external processing after sintering is reduced, and the stability of mass production is greatly improved.

According to the method for manufacturing a permanent magnet for a rotating electric machine according to the seventh aspect , the focusing is performed not on the entire permanent magnet but on only a part of the area including the demagnetization target area to the demagnetization target area. Since the easy axis of magnetization is oriented in the direction, the magnetic flux density in the area to be demagnetized can be increased, but the adverse effect of focusing the easy axis of magnetization (for example, a decrease in magnetic flux density in an area far from the area to be demagnetized, etc. ) Can be eliminated.

According to the method for manufacturing a permanent magnet for a rotating electric machine according to claim 8 , the radial direction or the parallel direction is set except for a part of the area where the axis of easy magnetization is oriented so as to converge to the area to be demagnetized. Since the axis of easy magnetization is oriented in a short time, it is possible to realize an appropriate orientation according to the type of rotating electric machine using a permanent magnet.

According to the method of manufacturing a permanent magnet for a rotating electric machine according to the ninth aspect , the orientation direction is corrected by deforming the magnetically oriented mixture once, and the easy axis of magnetization is appropriately shifted to the demagnetization target area. It is possible to orient so as to focus. As a result, it is possible to perform high orientation and orientation with little variation. Further, when the mixture is formed into a molded body, the orientation direction can be corrected while deforming the molded body. As a result, the molding step and the orientation step of the permanent magnet can be performed in one step, and the productivity can be improved.

According to the method for manufacturing a permanent magnet for a rotating electric machine according to claim 10 , since the magnetic field orientation is performed after the mixture is once formed into a sheet, and then the formed body is deformed, the molding process and the magnetic field orientation are performed. The process can be performed efficiently in a continuous process, and the productivity can be improved.

Further, according to the method for manufacturing a rotating electric machine according to the eleventh aspect , it is possible to prevent a decrease in torque and power generation even if demagnetization occurs in a permanent magnet arranged in the rotating electric machine.

1 is an overall view showing a permanent magnet according to the present invention. FIG. 2 is a diagram showing an embedded magnet type motor in which permanent magnets are arranged. FIG. 3 is a diagram illustrating an easy axis direction of a permanent magnet. FIG. 4 is a diagram illustrating an area where demagnetization is likely to occur in a permanent magnet arranged in the embedded magnet type motor. FIG. 3 is a diagram illustrating an easy axis direction of a permanent magnet. FIG. 3 is a diagram illustrating an area where demagnetization is likely to occur in a permanent magnet arranged in a surface magnet type motor. It is an explanatory view showing a permanent magnet concerning the present invention, and a manufacturing process of a rotary electric machine using a permanent magnet. It is an explanatory view showing a permanent magnet concerning the present invention, and a manufacturing process of a rotary electric machine using a permanent magnet. FIG. 3 is an explanatory view showing a green sheet forming step and a magnetic field orienting step, among the steps of manufacturing the permanent magnet according to the present invention. FIG. 4 is a diagram illustrating a temperature rising mode in a calcining step in the manufacturing steps of the permanent magnet according to the present invention.

  Hereinafter, an embodiment of a permanent magnet for a rotating electric machine according to the present invention, a method for manufacturing the permanent magnet for the rotating electric machine, and a rotating electric machine using the permanent magnet for the rotating electric machine and a method for manufacturing the rotating electric machine will be described in detail with reference to the drawings. This will be described in detail with reference to FIG.

[Configuration of permanent magnet]
First, the configuration of the permanent magnet 1 corresponding to the permanent magnet for a rotating electrical machine 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 a permanent magnet having a substantially rectangular parallelepiped shape having a trapezoidal cross section. Then, as shown in FIG. 2, the magnet (or generator) 2 is housed in a housing (slot) 4 formed in the rotor 3 of the magnet (or generator) 2 to form the motor (or generator). I do. FIG. 2 is a diagram showing an embedded magnet type motor (hereinafter referred to as an IPM motor) 2 in which a permanent magnet 1 is arranged. In the following embodiment, an example will be described in which the shape of the permanent magnet 1 is a substantially rectangular parallelepiped shape having a trapezoidal cross section, but the shape of the permanent magnet 1 is appropriately changed according to the type and shape of the rotating electric machine to be arranged. It is possible. For example, the cross section may be an arc shape or a rectangular shape instead of a trapezoidal shape. Further, the present invention can be applied to a surface magnet type motor (or generator) such as an SPM motor, in addition to the embedded magnet type motor (or generator).

  Further, the permanent magnet 1 according to the present invention is made of a Nd-Fe-B-based magnet. The content of each component is Nd: 27 to 40 wt%, B: 0.8 to 2 wt%, and Fe (electrolytic iron): 60 to 70 wt%. Further, 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 used. May contain a small amount.

  Further, the permanent magnet 1 is formed by a molded body (green molded body) obtained by molding a mixture of a magnet powder and a binder as described later. It should be noted that the mixture is not directly formed into the substantially rectangular parallelepiped shape shown in FIG. 1, but is once formed into a shape other than the substantially rectangular parallelepiped shape (for example, a sheet shape, a block shape, or the like), and thereafter is punched, cut, deformed, or the like. By performing the above, a configuration having a substantially rectangular parallelepiped shape may be adopted. In particular, if the mixture is formed into a sheet shape and then processed into a substantially rectangular parallelepiped shape, productivity can be improved by producing the mixture in a continuous process, and the precision of molding can be improved. When the mixture is formed into a sheet shape, the mixture is formed into a thin sheet member having a thickness of, for example, 0.05 mm to 10 mm (for example, 1 mm). Incidentally, even in the case of a sheet shape, a large-sized permanent magnet 1 can be manufactured by laminating a plurality of sheets.

  Further, the permanent magnet 1 according to the present invention is an anisotropic magnet, and the easy axis (C axis) is oriented as shown in FIG. Here, when viewed from the cross section, the permanent magnet 1 is basically divided into three areas, a first area 5 located on the left side of the trapezoid, a second area 6 located on the right side of the trapezoid, And a third area 7 located at the center of the trapezoid. The easy axis is oriented in a different direction for each area.

  Specifically, the first area 5 and the second area 6 have an axis of easy magnetization such that the first axis 5 and the second area 6 are focused on a specific area (hereinafter, referred to as a demagnetization target area) included in the first area 5 and the second area 6. It is oriented obliquely. On the other hand, in the third area 7, the easy axis is oriented in the parallel direction without converging the easy axis. That is, the first area 5 and the second area 6 correspond to the focusing target area according to the present invention. In the first area 5 and the second area 6, the axis of easy magnetization (C-axis) may be oriented so as to converge linearly to the area to be demagnetized, or to the area to be demagnetized along a curve. May be oriented so as to converge.

  Here, the demagnetization target area which is the target of focusing the easy axis in the first area 5 and the second area 6 is an area inside the magnet, and the permanent magnet 1 is connected to the IPM motor 2 as shown in FIG. When it is arranged on the rotor 3, it is an area that is more likely to be demagnetized than other areas. More specifically, it is near both end angles of the side facing the stator and the air gap. The reason why the demagnetization target area shown in FIG. 4 is more likely to be demagnetized than the other areas is considered to be that a large demagnetizing field is generated due to the short-circuit of the magnetic flux lines.

  Further, in the example shown in FIG. 3, the third area 7 has a configuration in which the axis of easy magnetization is oriented in the parallel direction, but may have a configuration in which the third area 7 is oriented in the radial direction (radial direction). Further, the size ratio of the first area 5, the second area 6, and the third area 7 can be appropriately changed. For example, the first area 5 may be larger than the second area 6. In the example shown in FIG. 3, the permanent magnet 1 is divided into three areas. However, the permanent magnet 1 is divided into two or four or more areas, and the easy magnetization axis is oriented in a different direction for each area. May be. As a result, even if there are three or more demagnetization target areas, it is possible to orient the magnetization easy axis to converge to each demagnetization target area.

  Then, when the permanent magnet 1 is oriented as shown in FIG. 3, when the permanent magnet 1 is disposed on the IPM motor 2, the easy axis (C axis) is focused on the demagnetization target area that is easily demagnetized. Orientation. As a result, when the permanent magnet 1 is arranged on the IPM motor 2 and magnetized, the magnetic flux inside the magnet concentrates on the demagnetization target area where the magnet is easily demagnetized (that is, the magnetic flux density increases). . Therefore, even if the permanent magnet 1 is demagnetized with the use of the IPM motor 2, it is possible to maintain a necessary and sufficient surface magnetic flux density. Further, since the axis of easy magnetization is inclined and oriented so as to focus on the first area 5 and the second area 6 but not on the entire permanent magnet 1, the magnetic flux in the demagnetization target area is focused. While the density can be increased, it is possible to eliminate the adverse effects (for example, a decrease in the magnetic flux density in an area far from the demagnetization target area) caused by focusing the easy axis. In addition, if the first area 5 and the second area 6 are made larger than the third area 7, the magnetic flux inside the magnet can be concentrated in the area to be demagnetized. There is a high possibility that adverse effects due to the above will occur.

  Next, a case where the permanent magnet 1 according to the present invention is applied to a surface magnet type motor (SPM motor) will be described. When applied to an SPM motor, as shown in FIG. 5, the permanent magnet 1 has a segment shape, and a first area 8 located on the left side, a second area 9 located on the right side, and a third area 9 located in the center. And an area 10.

  The first area 8 and the second area 9 are oriented with their easy axes of magnetization inclined so as to converge on the demagnetization target area. On the other hand, in the third area 10, the easy axis is oriented in the radial direction (radial direction) without focusing the easy axis. That is, the first area 8 and the second area 9 correspond to the focusing target area according to the present invention. Here, in the first area 8 and the second area 9, the demagnetization target area which is a target for focusing the easy axis is, when the permanent magnet 1 is arranged on the rotor 3 of the SPM motor as shown in FIG. This is an area that is more likely to be demagnetized than the area of FIG. More specifically, it is near both end angles of the side facing the stator and the air gap.

  In the first area 8 and the second area 9, the axis of easy magnetization (C-axis) may be oriented so as to converge linearly to the area to be demagnetized, or to the area to be demagnetized along a curve. May be oriented so as to converge.

  In the example shown in FIG. 5, the third area 10 has a configuration in which the axis of easy magnetization is oriented in the radial direction, but may have a configuration in which the third area 10 is oriented in the parallel direction (parallel direction). Further, the size ratio of the first area 8, the second area 9, and the third area 10 can be appropriately changed. For example, the first area 8 may be larger than the second area 9. In the example shown in FIG. 5, the permanent magnet 1 is divided into three areas. However, the permanent magnet 1 is divided into two or four or more areas, and the easy magnetization axis is oriented in a different direction for each area. May be.

  Then, even when the permanent magnet 1 is oriented as shown in FIG. 5, the magnetic flux inside the magnet concentrates on the demagnetization target area which is easily demagnetized similarly to FIG. 3 (that is, the magnetic flux density becomes high). Becomes Therefore, even if the permanent magnet 1 is demagnetized due to the use of the SPM motor, it is possible to maintain a necessary and sufficient surface magnetic flux density. In addition, since the easy axis is inclined and oriented so that only the first area 8 and the second area 9 are focused on the area to be demagnetized, adverse effects caused by focusing the easy axis (for example, Magnetic flux density is reduced in an area far from the area).

  Further, in the permanent magnet 1 according to the present invention, since a magnetic field is applied to a mixture obtained by mixing a magnet powder and a binder to orient the magnet particles as described later, the magnet particles are subjected to pressure applied after the orientation as in the case of powder compaction. Does not rotate, and the degree of orientation can be improved. Further, since there is no variation in the density distribution of the magnet powder unlike the PLP method, the near net shape is improved. Further, a magnetic field is applied to the mixture before molding into a product shape (for example, a substantially rectangular parallelepiped shape shown in FIG. 1) to perform orientation once, and then the mixture is molded in consideration of the direction of the axis of easy magnetization of the mixture ( For example, if the product is formed into a product shape, the direction of the axis of easy magnetization can be manipulated in the process of forming the product shape. That is, the easy axis of magnetization can be appropriately oriented in the direction intended by the manufacturer. As a result, a permanent magnet having an easy axis of magnetization oriented in a complicated direction (for example, an anisotropic magnet oriented so as to focus the easy axis of magnetization as shown in FIGS. 3 and 5 in a specific direction) can be easily and accurately formed. It can be realized.

  Further, as described above, the permanent magnet 1 according to the present invention includes an area (for example, the first areas 5, 8 and the second areas 6, 9) in which the axis of easy magnetization is oriented to the area to be demagnetized. Are divided into parallel or radially oriented areas (eg, third areas 7 and 10) without converging the axis of easy magnetization. When molding the mixture into a product shape, each area is different. It is good also as a final product shape by shape | molding with a molded object and joining before and after sintering each molded object with magnetic field orientation. In this case, a step of joining the molded bodies is newly required as compared with the case where the respective areas are integrally molded. However, the magnetic field orientation step is easy and high orientation can be realized.

（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, particularly 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.
Further, when a resin is used as the binder, it is preferable to use a depolymerizable polymer that does not contain an oxygen atom in the structure. In addition, as described later, in order to reuse the residue of the mixture generated when the mixture of the magnet powder and the binder is formed into a desired shape (for example, a substantially rectangular parallelepiped shape), and to heat the mixture to a magnetic field in a softened state. In order to perform orientation, a thermoplastic resin is used. Specifically, a polymer composed of one or more polymers or copolymers selected from the monomers represented by the following general formula (1) corresponds to the above.

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

Examples of the polymer corresponding to 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) which is a polymer of 1,3-butadiene. Rubber, BR), polystyrene which is a polymer of styrene, styrene-isoprene block copolymer (SIS) which is a copolymer of styrene and isoprene, butyl rubber (IIR) which is a copolymer of isobutylene and isoprene, styrene and butadiene A styrene-butadiene block copolymer (SBS), a copolymer of 2-methyl-1-pentene, a polymer of 2-methyl-1-pentene, and a polymer of 2-methyl-1-butene. Certain 2-methyl-1-butene polymer resin, α-methylstyrene polymer That there is α- methyl styrene polymer resin. In addition, it is desirable to add low molecular weight polyisobutylene to the α-methylstyrene polymer resin in order to give flexibility. Further, the resin used for the binder may be configured to contain a small amount of a polymer or copolymer of a monomer containing an oxygen atom (for example, polybutyl methacrylate or polymethyl methacrylate). Further, a monomer which 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 the resin used for the binder, a thermoplastic resin that softens at 250 ° C. or less 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 less 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) which 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 magnet powder and the binder is magnetically oriented as described later, the magnetic field is oriented in a state where the mixture is heated at a temperature equal to or higher than the glass transition point or the flow start temperature of the long-chain hydrocarbon and softened.

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

  By using a binder satisfying the above conditions as the binder mixed with the magnet powder, it becomes possible to reduce the amount of carbon and the amount of oxygen contained in the magnet. Specifically, the amount of carbon remaining in the magnet after sintering is set to 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 to be added is such that the gap between the magnet particles is appropriately filled in order to improve the thickness accuracy of the molded body when molding the slurry or the compound melted by heating. 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]
The permanent magnet type IPM motor 2 in which the permanent magnet 1 is accommodated in the slot 4 of the rotor 3 includes a stator 11 and a rotor 3 rotatably arranged inside the stator 11 as shown in FIG. It is basically composed of

  The stator 11 basically includes a stator core 12 made of a magnetic material such as an electromagnetic steel sheet and a plurality of windings 13 wound around the stator core 12. Further, the stator core 12 includes an annular yoke and a plurality of teeth projecting radially outward from the yoke, and the winding 13 is wound around the teeth. The winding of the winding 13 is classified into a concentrated winding method and a distributed winding method. The concentrated winding method is a form in which the winding 13 is wound for each tooth, and the distributed winding method is a form in which the winding 13 is wound over a plurality of teeth.

  On the other hand, a slot 4 in which the permanent magnet 1 is accommodated is formed in the rotor 3. A plurality (four in FIG. 2) of slots 4 are formed in a shape (for example, a trapezoidal cross section) corresponding to the permanent magnet 1 along the axial direction of the rotor 3. Note that a void may be formed at the end of the slot 4 as a flux barrier. The above-mentioned permanent magnet 1 is arranged in the slot 4. Note that the permanent magnet 1 is fixed to the slot 4 via the filler filled in the slot 4. As the filler, for example, an epoxy resin or a silicone resin can be used.

  Further, the permanent magnet 1 according to the present invention is an anisotropic magnet, and the axis of easy magnetization (C axis) is oriented, for example, in the direction shown in FIG. As a result, when the permanent magnet 1 is accommodated in the slot 4 of the rotor 3 and a magnetic field is applied in parallel to the axis of easy magnetization of the permanent magnet 1 to perform magnetization, a magnetic field for realizing the IPM motor 2 is formed. It is possible to do. Further, as described above, the magnetized permanent magnet 1 is configured such that the magnetic flux concentrates on the demagnetization target area where demagnetization is likely to occur.

  On the other hand, at the center of the rotor 3, a rotating shaft 14 having one end fixed to the rotor 3 is provided. The rotation shaft 14 is configured to rotate with the rotation of the rotor 3 when the rotor 3 rotates.

  In the IPM motor 2 having the above configuration, when a current is applied to the winding 13 of the stator 11, a magnetic attractive force and a repulsive force are generated between the rotor 3 and the stator 11, and the rotor 3 is rotated about the rotating shaft 14. Rotates. Further, by configuring the magnetic flux to concentrate on the demagnetization target area where demagnetization is likely to occur, it is possible to prevent a decrease in torque due to demagnetization.

[Manufacturing method of permanent magnet and rotating electric machine using permanent magnet]
Next, a permanent magnet 1 according to the present invention and a method for manufacturing a rotating electric machine using the permanent magnet 1 will be described with reference to FIGS. FIGS. 7 and 8 are explanatory views showing the permanent magnet 1 according to the present embodiment and the manufacturing process of the rotating electric machine using the permanent magnet 1.

  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 crushed to a size of about 200 μm by a stamp mill, a crusher, or the like. Alternatively, the ingot is melted, flakes are produced by a strip casting method, and coarsened by a hydrogen disintegration method. Thereby, coarsely ground magnet powder 15 is obtained.

  Next, the coarsely ground magnet powder 15 is finely ground by a wet method using a bead mill 16, a dry method using a jet mill, or the like. For example, in the fine pulverization using a bead mill 16 using a wet method, 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. There is no particular limitation on the type of solvent used for pulverization, and alcohols such as isopropyl alcohol, ethanol, and methanol; esters such as ethyl acetate; lower hydrocarbons such as pentane and hexane; and aromatics such as benzene, toluene, and xylene. , Ketones, mixtures thereof and the like can be used. Preferably, a solvent containing no oxygen atom in the solvent is used.

  On the other hand, in the fine pulverization using a dry method by a jet mill, the coarsely pulverized magnet powder is mixed in an atmosphere consisting of (a) an inert gas such as nitrogen gas, Ar gas, or He gas having an oxygen content of substantially 0%. Or (b) finely pulverized with a jet mill in an atmosphere composed of an inert gas such as nitrogen gas, Ar gas, or He gas having an oxygen content of 0.0001 to 0.5%, and a particle size in a predetermined range (for example, (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%, and the oxygen concentration may be such that an oxide film is formed only slightly 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 molding of the magnet powder is performed by molding a mixture of the magnet powder and the binder. In the following examples, a magnetic field is applied by applying a magnetic field in a state where the mixture is once formed into a product shape other than the product shape, and thereafter, the product shape (for example, as shown in FIG. (Substantially rectangular parallelepiped 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) and then formed into a product shape. Further, when the mixture is particularly formed into a sheet shape, for example, a hot melt coating in which a compound in which magnet powder and a binder are mixed is heated and then formed into a sheet shape, or a slurry containing a magnet powder, a binder, and an organic solvent is used. Is formed into a sheet by coating the substrate on a substrate.

Hereinafter, particularly, green sheet molding using hot melt coating will be described.
First, a clay-like mixture (compound) 17 composed of a magnet powder and a binder is prepared by mixing a binder with the magnet powder finely pulverized by a bead mill 16 or the like. Here, as described above, a resin, a long-chain hydrocarbon, a fatty acid ester, a mixture thereof, or the like is used as the binder. For example, in the case of using a resin, the structure does not contain an oxygen atom, and a thermoplastic resin made of a polymer having depolymerizability is used. It is preferable to use a long-chain saturated hydrocarbon (long-chain alkane) which is a liquid. When a fatty acid ester is used, it is preferable to use methyl stearate, methyl docosanoate, or the like. As described above, the amount of the binder 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%, and still more preferably 3 wt%. % To 20 wt%.

  Further, the compound 17 may be added with an additive that promotes the orientation in order to improve the degree of orientation in a magnetic field orientation step performed later. As the additive that promotes the orientation, for example, a hydrocarbon-based additive is used. In particular, a polar additive (specifically, an acid dissociation constant pKa of less than 41) is desirably used. In addition, the amount of the additive depends on the particle size of the magnet powder, and the smaller the particle size of the magnet powder, the larger the amount of the additive. The specific addition amount is 0.1 to 10 parts, more preferably 1 to 8 parts, based on 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 a magnetic field orientation process described later. As a result, the orientation is easily performed when a magnetic field is applied, and the direction of the easy axis of magnetization 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 increases, and the orientation of the particles decreases, so that the effect of adding the additive becomes greater.

  The binder is added in an atmosphere composed of an inert gas such as a nitrogen gas, an Ar gas, and a 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 a stirrer. Heating and stirring may be performed to promote kneading. The mixing of the magnet powder and the binder is desirably performed in an atmosphere composed of an inert gas such as nitrogen gas, Ar gas, and He gas. In particular, when the magnet powder is pulverized by a wet method, the binder is added to the solvent and kneaded without removing the magnet powder from the solvent used for the pulverization, and then the solvent is volatilized. It is good also as a structure obtained.

  Subsequently, the compound 17 is formed into a sheet to form a green sheet. In particular, in the hot melt coating, the compound 17 is melted by heating the compound 17 to be in a fluid state, and then coated on a supporting substrate 18 such as a separator. Thereafter, heat is released and solidified to form a long sheet-like green sheet 19 on the support base material 18. The temperature at which the compound 17 is heated and melted varies depending on the type and amount of the binder used, but is set to 50 to 300 ° C. However, the temperature must be higher than the flow start temperature of the binder used. In the case of using slurry coating, the magnet powder and binder (which may further include an additive that promotes orientation) may be dispersed in a large amount of solvent, and the slurry may be coated on a supporting substrate 18 such as a separator. Work. Thereafter, by drying and evaporating the solvent, a long sheet-like green sheet 19 is formed on the support base material 18.

  Here, as a coating method of the molten compound 17, it is preferable to use a method excellent in 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 a comma coating method that is particularly excellent in layer thickness controllability (that is, a method capable of coating a layer with a high precision thickness on the surface of a substrate). It is desirable to use For example, in the slot die method, the coating is performed by extruding the compound 17 which has been heated to be in a fluid state by a gear pump and inserting it into the die. In the calender roll method, a fixed amount of the compound 17 is charged into the gap between the heated two rolls, and the compound 17 melted by the heat of the roll is coated on the support base 18 while rotating the roll. Further, as the support base material 18, for example, a silicone-treated polyester film is used. Further, it is preferable to sufficiently perform a defoaming treatment by using an antifoaming agent, or performing a heat vacuum defoaming so that no air bubbles remain in the spread layer. In addition, instead of coating on the support base material 18, the compound 17 melted by extrusion or injection molding is formed into a sheet shape and extruded onto the support base material 18, so that the green sheet is formed on the support base material 18. 19 may be formed.

  In the step of forming the green sheet 19 by the slot die method, it is preferable to 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, to a fluctuation of ± 0.1% or less), and the fluctuation of the coating speed is also 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 still more preferably within ± 1% of a design value (for example, 1 mm). In the other calender roll method, it is possible to control the film thickness of the compound 17 transferred to the supporting substrate 18 by similarly controlling the calender conditions based on the actually measured values.

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

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

  The temperature and time for heating the green sheet 19 vary depending on the type and amount of the binder used, but are, for example, 0.1 to 60 minutes at 100 to 250 ° C. However, in order to soften the green sheet 19, the temperature must be higher than the glass transition point or the flow start temperature of the binder used. Examples of the heating method for heating the green sheet 19 include 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 in the in-plane direction and the length direction of the green sheet 19 softened by heating. The intensity 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 axis of magnetization) of the magnet crystal included in the green sheet 19 is oriented in one direction. The magnetic field may be applied in the in-plane direction and the width direction of the green sheet 19. Further, a configuration in which a magnetic field is simultaneously applied to a plurality of green sheets 19 may be adopted.

  Further, when applying a magnetic field to the green sheet 19, a step of applying a magnetic field simultaneously with the heating step may be performed, or the magnetic field may be applied after the heating step and before the green sheet solidifies. May be performed. Alternatively, the green sheet 19 coated by hot melt coating may be magnetically oriented before solidifying. In that case, the heating step becomes unnecessary.

  Next, the heating step of the green sheet 19 and the magnetic field orientation step will be described in more detail with reference to FIG. FIG. 9 is a schematic view showing a heating process of the green sheet 19 and a magnetic field orientation process. In the example shown in FIG. 9, an example in which the magnetic field orientation step is performed simultaneously with the heating step will be described.

  As shown in FIG. 9, the heating and the magnetic field orientation of the green sheet 19 coated by the slot die method described above are performed on the long sheet-like green sheet 19 continuously conveyed by rolls. That is, an apparatus for performing heating and magnetic field orientation is arranged on the downstream side of a coating apparatus (die or the like), and the heating and the magnetic field orientation are performed in a step continuous with the above-described coating step.

Specifically, the solenoid 25 is arranged on the downstream side of the die 20 and the coating roll 22 so that the transported support base material 18 and green sheet 19 pass through the solenoid 25. Further, the hot plate 26 is arranged in a pair above and below the green sheet 19 in the solenoid 25. The green sheet 19 is heated by a pair of upper and lower hot plates 26 and an electric current is applied to the solenoid 25 so that the green sheet 19 extends in the in-plane direction of the long sheet-like green sheet 19 (that is, the sheet surface of the green sheet 19). A magnetic field is generated in the direction parallel to the vertical direction) and in the longitudinal direction. Thereby, the continuously conveyed green sheet 19 is softened by heating, and a magnetic field is applied in the in-plane direction and the length direction (the direction of the arrow 27 in FIG. 9) of the softened green sheet 19, and Appropriate and uniform magnetic field orientation can be realized. In particular, by setting the direction in which the magnetic field is applied to the in-plane direction, the surface of the green sheet 19 can be prevented from standing upside down.
Further, it is preferable that the heat radiation and solidification of the green sheet 19 performed after the magnetic field orientation is performed in a transport 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. Then, by applying a current to each magnetic field coil, it is possible to generate a magnetic field in the in-plane direction and the width direction of the long sheet-like green sheet 19.

  Further, the orientation of the magnetic field can be set in 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 is applied by a magnetic field applying device using a pole piece or the like. When the direction of the magnetic field is perpendicular to the surface of the green sheet 19, it is preferable to laminate a film on the opposite surface of the green sheet 19 on which the support base material 18 is laminated. Thereby, it is possible to prevent the surface of the green sheet 19 from standing upside down.

  Further, instead of the above-described heating method using the hot plate 26, 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 a high fluidity such as a slurry by a general slot die method, a doctor blade method, or the like 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 to the one having a stronger magnetic field, so that the slurry of the green sheet 19 becomes liquid, that is, the thickness of the green sheet 19 becomes uneven. This may occur. In contrast, when the compound 17 is formed into a 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 of Pa · s, There is no powder shift. Furthermore, the viscosity of the binder is reduced by being conveyed and heated in a uniform magnetic field, and uniform C-axis orientation can be achieved only by rotating torque in the uniform magnetic field.

  When the green sheet 19 is formed from a highly fluid liquid such as a slurry containing an organic solvent by a general slot die method or a doctor blade method without using hot melt molding, the thickness exceeds 1 mm. When an attempt is made to form a sheet, foaming due to the vaporization of the organic solvent contained in the slurry or the like during drying becomes a problem. Furthermore, if the drying time is lengthened to suppress foaming, sedimentation of the magnet powder occurs, which causes a bias in the density distribution of the magnet powder in the direction of gravity, and causes warpage after firing. Therefore, in forming from a slurry, the upper limit of the thickness is substantially regulated, so that it is necessary to form a green sheet with a thickness of 1 mm or less and then laminate the green sheet. However, in this case, the entanglement between the binders becomes poor, and delamination occurs in the subsequent binder removal step (calcination treatment), which lowers the C-axis (easy axis of magnetization) orientation, that is, the residual magnetic flux density ( Br). On the other hand, when the compound 17 is formed into the green sheet 19 by hot melt molding as in the present invention, since the organic solvent is not contained, even when a sheet having a thickness exceeding 1 mm is formed, the above-described foaming is not performed. Concerns are gone. Since the binder is in a sufficiently entangled state, there is no possibility that delamination occurs in the binder removal step.

  When a magnetic field is simultaneously applied to a plurality of green sheets 19, for example, a plurality of (for example, six) green sheets 19 are continuously transported in a stacked state, and the stacked green sheets 19 pass through the solenoid 25. It is configured to pass. Thereby, productivity can be improved.

  Then, after the green sheet 19 is oriented in the magnetic field by the method shown in FIG. 9, a load is applied to the green sheet 19 to deform the green sheet 19 and form the green sheet 19 into a product shape. Note that the direction of the easy axis is displaced by the above deformation so as to be the direction of the easy axis required in the final product. As a result, as shown in FIG. 3, the easy axis of the first area 5 and the second area 6 is focused on the area to be demagnetized, and the easy axis of the third area 7 is focused in the parallel direction without focusing the easy axis. It is possible to manipulate the direction of the easy axis of magnetization so as to be oriented in the radial direction. It should be noted that the green sheet 19 is required to be shaped in consideration of the shape of the final product and the direction of the axis of easy magnetization required in the final product before being deformed (that is, required in the final product when the green sheet 19 is deformed to have the final product shape). It is punched in advance into a shape that can realize the direction of the axis of easy magnetization, and then deformed.

  Further, in the permanent magnet 1 according to the present invention, the area (for example, the first area 5 and the second area 6) oriented so that the axis of easy magnetization is focused on the area to be demagnetized and the axis of easy magnetization are focused. Instead, the area is divided into an area oriented in the parallel direction or the radial direction (for example, the third area 7), but each area may be molded integrally or separately.

  For example, when forming integrally (pattern 1), first, a magnetic field is applied in a direction perpendicular to the surface of the linear green sheet 19. Thereafter, the green sheet 19 is punched into a shape corresponding to the product shape (for example, a rectangular parallelepiped shape), and a load is applied from both ends in the width direction of the punched green sheet 19 to the center side so that the upper side is reduced to form a trapezoidal shape. I do. As a result, the direction of the axis of easy magnetization of the green sheet 19 is also corrected along with the deformation of the green sheet 19, and it is possible to manufacture the molded body 30 having the orientation shown in FIG. By optimizing the direction and value of the load applied to the green sheet 19, the easy axis of magnetization in the central third area 7 is maintained in the parallel direction, and the left and right first area 5 and the second area 6 are kept parallel. Only the axis of easy magnetization can be tilted.

  On the other hand, when forming into a separate body (pattern 2), first, a magnetic field is applied in a direction perpendicular to the surface of the linear green sheet 19. Next, by punching out the green sheet 19, a first molded body 31 corresponding to the first area 5, a second molded body 32 corresponding to the second area 6, and a third molded body corresponding to the third area 7 are formed. 33 are each molded. Thereafter, the first molded body 31 and the second molded body 32 are deformed into a trapezoidal shape by applying a load to the center from both sides to shrink the upper side. As a result, the directions of the axes of easy magnetization of the first molded body 31 and the second molded body 32 are corrected with the deformation of the first molded body 31 and the second molded body 32, and the first molded body 31 and the second molded body 32 are deformed. With regard to 32, the cross section in which the axis of easy magnetization is focused on the upper side becomes a trapezoidal shaped body. On the other hand, the third molded body 33 is not deformed, and maintains the orientation in the parallel direction. Thereafter, by joining the molded bodies 31 to 33, the molded body 30 having the orientation as shown in FIG. 3 can be manufactured. The joining of the molded bodies 31 to 33 is performed by an adhesive, a plasticizer, and thermocompression bonding. The joining of the molded bodies 31 to 33 may be performed before sintering, or may be performed after sintering.

  When a large-sized magnet is manufactured, a plurality of green sheets 19 deformed to the same shape may be laminated and formed by fixing each other with a resin or the like. Note that the green sheets 19 may be deformed after being laminated. Further, a configuration may be adopted in which after a molded body corresponding to the product shape is molded, a magnetic field is applied to the molded body to perform magnetic field orientation. Further, when performing the magnetic field orientation after molding the molded body, the magnetic field orientation may be performed by applying the magnetic field to the molded body accommodated in the slot 4 after accommodating the molded body in the slot 4. It is possible.

  Thereafter, the molded body 30 subjected to molding and magnetic field orientation is pressurized to atmospheric pressure or a pressure higher or lower than the atmospheric pressure (for example, 1.0 Pa or 1.0 MPa). Alternatively, the calcination treatment is performed by maintaining the binder decomposition temperature for several hours to several tens of hours (for example, 5 hours) in a mixed gas atmosphere of hydrogen and an inert gas. 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, it becomes possible to decompose an organic compound such as a binder into a monomer by a depolymerization reaction or the like and to scatter and remove the monomer. That is, so-called decarbonization for reducing the amount of carbon in the molded body 30 is performed. The calcination 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. Thereby, it becomes possible to sinter the entire compact 30 in the subsequent sintering process, thereby suppressing a decrease in residual magnetic flux density and coercive force. Further, in the case where the pressurizing condition at the time of performing the above-described calcination treatment is a pressure higher than the atmospheric pressure, the pressure is desirably 15 MPa or less. In addition, when the pressurizing condition is set to a pressure higher than the atmospheric pressure, more specifically, 0.2 MPa or more, an effect of particularly reducing the carbon amount can be expected.

  In addition, the binder decomposition temperature is determined based on the analysis result of the binder decomposition product and the decomposition residue. Specifically, a temperature range is selected in which the decomposition products of the binder are collected, no decomposition products other than the monomer are generated, and no product due to the side reaction of the remaining binder component is detected in the analysis of the residue. Although it depends on the type of the binder, the temperature is set to 200 ° C to 900 ° C, more preferably 400 ° C to 600 ° C (for example, 450 ° C).

  Further, in the calcination treatment, it is preferable to reduce the rate of temperature rise as compared with the case where general magnet sintering is performed. Specifically, the heating rate is set to 2 ° C./min or less (for example, 1.5 ° C./min). Therefore, when performing the calcination treatment, as shown in FIG. 10, the temperature is raised at a predetermined rate of 2 ° C./min or less, and after reaching a preset temperature (binder decomposition temperature), The calcining process is performed by maintaining the set temperature for several hours to several tens hours. By reducing the heating rate in the calcination treatment as described above, the carbon in the compact 30 is not removed abruptly but is removed stepwise, so that the density of the sintered permanent magnet is increased ( That is, the gap in the permanent magnet can be reduced). If the heating rate is 2 ° C./min or less, the density of the permanent magnet after sintering can be 95% or more, and high magnet properties can be expected.

Alternatively, the dehydrogenation treatment may be performed by holding the molded body 30 calcined by the calcination treatment in a vacuum atmosphere. 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) In addition, the activity of the compact 30 activated by the calcination treatment is reduced. Thereby, even when the molded body 30 calcined by the calcining treatment is subsequently moved to the atmosphere, it is possible to prevent Nd from binding to oxygen and to suppress a decrease in residual magnetic flux density and coercive force. I do. Further, an effect of returning the structure of the magnet crystal from NdH ₂ or the like to the Nd ₂ Fe ₁₄ B structure can also be expected.

  Subsequently, a sintering process for sintering the molded body 30 calcined by the calcining process is performed. The method of sintering the compact 30 is pressureless sintering in a vacuum, uniaxial pressure sintering in which the material is sintered in a uniaxially pressed state, and sintering in a state of being pressed in a biaxial direction. Biaxial pressure sintering, and isotropic pressure sintering in which sintering is performed in an isotropically pressed state. For example, uniaxial pressure sintering in which the compact 30 is sintered in a state where the compact 30 is pressed in a direction that is the same as the axial direction of the rotor 3 when accommodated in the slot 4 is used. The pressure sintering includes, for example, hot press sintering, hot isostatic pressing (HIP) sintering, ultra-high pressure synthetic sintering, gas pressure sintering, discharge plasma (SPS) sintering, and the like. . However, it is preferable to use SPS sintering that can be pressurized in a uniaxial direction and sinters by electric current sintering. When sintering is performed by SPS sintering, the pressure value is set to, for example, 0.01 MPa to 100 MPa, the pressure is increased to 940 ° C. at a rate of 10 ° C./min in a vacuum atmosphere of several Pa or less, and then maintained for 5 minutes. Is preferred. Then, it cools and heat-processes again at 300-1000 degreeC for 2 hours. Then, as a result of the sintering, a sintered body 35 is manufactured.

  Thereafter, the sintered body 35 accommodated in the slot 4 of the rotor 3 is magnetized along the C axis. Specifically, the plurality of sintered bodies 35 accommodated in the rotor 3 are magnetized such that N poles and S poles are alternately arranged along the circumferential direction of the rotor 3. As a result, the permanent magnet 1 can be manufactured. For the magnetization of the sintered body 35, for example, a magnetized coil, a magnetized yoke, a capacitor-type magnetized power supply, or the like is used. The permanent magnet 1 may be magnetized before being housed in the slot 4.

  After that, the IPM motor 2 is manufactured by assembling members other than the rotor 3 such as the stator 11 and the rotating shaft 14.

As described above, in the permanent magnet 1 and the method of manufacturing the permanent magnet 1 according to the present embodiment, the compound 17 is generated by crushing the magnet raw material into magnet powder and mixing the crushed magnet powder with the binder. . Then, a green sheet 19 is formed by molding the compound 17 into a sheet. Thereafter, a magnetic field is applied to the formed green sheet 19 to apply a magnetic field, and the green sheet 19 is formed into a product shape by deforming the green sheet 19 in consideration of the magnetic field orientation of the green sheet 19 that has been subjected to the magnetic field orientation. . After that, the permanent magnet 1 is manufactured by sintering. In addition, since the axis of easy magnetization is oriented so that the permanent magnet 1 converges to an area that is more likely to be demagnetized than other areas, by controlling the direction of orientation of the axis of easy magnetization, the area of the permanent magnet 1 becomes more easily demagnetized. On the other hand, the magnetic flux can be concentrated, and even if demagnetization occurs, a necessary and sufficient surface magnetic flux density can be maintained. As a result, it is possible to prevent the torque and the power generation amount of the rotating electric machine from gradually decreasing with the use of the rotating electric machine. In addition, if the demagnetization resistance can be increased, the magnet volume can be reduced while maintaining the required demagnetization resistance, so that the downsizing of the permanent magnet and the reduction of the manufacturing cost can be realized. For example, the balance between the performance of the permanent magnet and the manufacturing cost can be kept optimal by reducing the magnet volume to the lower limit that can ensure the required demagnetization resistance.
Further, since the axis of easy magnetization is oriented so as to focus not on the entire permanent magnet 1 but on a part of the area including the demagnetization target area, the magnetic flux density in the demagnetization target area is focused. Can be increased, but the adverse effect of focusing the easy axis (for example, a decrease in magnetic flux density in an area far from the demagnetization target area) can be eliminated.
Also, except for some areas where the easy axis is oriented so as to converge to the area to be demagnetized, the easy axis is oriented in the radial or parallel direction. It is possible to realize an appropriate appropriate orientation.
In addition, by forming a mixture of the magnet powder and the binder, it is possible to orient the magnetization easy axis appropriately to focus on the demagnetization target area. As a result, it is possible to appropriately concentrate the magnetic flux after the magnetization, and it is possible to secure the demagnetization resistance and prevent the variation in the magnetic flux density.
In addition, 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 powder compacting or the like.
When the magnetic field orientation is performed on the mixture with the binder, the number of turns of the current can be used, so that a large magnetic field strength can be secured when the magnetic field orientation is performed. , It is possible to realize a high degree of orientation with little variation. Then, if the orientation direction is corrected after the orientation, it is possible to secure a high orientation and an orientation with little variation.
Further, realization of high orientation with little variation leads to reduction in variation in shrinkage due to sintering. That is, uniformity of the product shape after sintering can be secured. As a result, it is expected that the burden on the external processing after sintering is reduced, and the stability of mass production is greatly improved.
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 axis of easy magnetization is manipulated by deforming the mixture to which the magnetic field is applied into a molded body. Since the orientation is performed, it is possible to correct the orientation direction by deforming the mixture once subjected to the magnetic field orientation, and to perform the orientation so that the easy axis of magnetization is appropriately focused on the demagnetization target area. As a result, it is possible to perform high orientation and orientation with little variation. In addition, when the mixture is formed into a molded body, the orientation can be corrected while deforming the molded body. As a result, the molding step and the orientation step of the permanent magnet can be performed in one step, and the productivity can be improved.
Also, since the magnetic field orientation is performed after the mixture is once formed into a sheet shape, and then the molded body is deformed, it is possible to efficiently perform the molding process and the magnetic field orientation process in a continuous process, thereby improving productivity. It is possible to do.
Further, in the rotating electric machine in which the permanent magnets 1 are arranged, even if the permanent magnets 1 are demagnetized, it is possible to prevent a decrease in torque or power generation.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various improvements and modifications can be made without departing from the spirit of the present invention.
For example, the pulverizing conditions, kneading conditions, molding conditions, magnetic field orientation step, 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. Further, the calcination may be performed in a non-oxidizing atmosphere other than a hydrogen atmosphere (for example, a nitrogen atmosphere, a He atmosphere, an Ar atmosphere, or the like). Further, the calcination treatment may be omitted. In that case, decarbonization will be performed during the sintering process.

  Further, in the above embodiment, the magnetic field orientation is performed after the mixture of the magnet powder and the binder is once formed into a sheet-shaped green compact, but the magnetic field orientation is performed after the mixture is molded into a shape other than the sheet shape. It is good. For example, you may shape | mold to a block-shaped green molded object. The block-shaped green compact oriented in the magnetic field is further processed into a substantially rectangular parallelepiped compact 30.

  Further, in the above embodiment, after the magnetic field orientation is performed on the mixture of the magnet powder and the binder, the mixture is formed into the substantially rectangular parallelepiped shaped body 30. After that, the magnetic field orientation may be performed. Further, the magnetic field orientation may be performed after the molded body 30 is accommodated in the slot 4.

  Further, in the above embodiment, the permanent magnet 1 has a substantially rectangular parallelepiped shape having a trapezoidal cross section. However, other shapes (for example, a bow shape or a semi-cylindrical shape) can be used according to the intended use. Furthermore, the shape of the magnetic flux density distribution to be realized can be appropriately changed depending on the shape and use of the permanent magnet.

  Further, the present invention can be applied to a rotating electric machine in which the permanent magnet 1 is arranged in a housing portion formed on the stator side instead of the rotor side. Further, the present invention is not limited to the inner rotor type rotating electric machine, and is applicable to an outer rotor type rotating electric machine. Further, the permanent magnet 1 can be applied to a surface magnet type rotating electric machine or a linear motor in which permanent magnets are arranged in a plane. Further, the permanent magnet 1 according to the present invention is applicable to various rotating electric machines such as a generator and a magnetic reduction gear other than the motor, and further to various devices using the permanent magnet 1 other than the rotating electric machine. When the rotating electric machine according to the present invention is applied to a magnetic reduction gear, the stator 11 is constituted by a predetermined number of magnetic pole pieces made of a magnetic material instead of the stator core 12 and the winding 13.

  Further, in the above embodiment, the rotating electric machine has the stator core 12 in which the winding 13 is wound around the stator core 12, but the stator core 12 may be made of a non-magnetic material other than the magnetic material. Further, the rotating electric machine may be a coreless motor having no stator core. In such a case, the stator 11 is formed by fixing the winding 13 in a cup shape with resin or the like. In such a coreless motor, since the iron loss can be eliminated, the efficiency of the rotating electric machine can be increased.

  Further, in the above embodiment, the magnet powder is molded and then calcined in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. However, the magnet powder before molding is calcined and calcined. The permanent magnet may be manufactured by molding a magnet powder, which is a body, into a compact and then performing sintering. With such a configuration, since the calcining is performed on the powdery magnet particles, the surface area of the magnet to be calcined is increased compared to the case of performing the calcining on the magnet particles after molding. can do. That is, it is possible to more reliably reduce the amount of carbon in the calcined body. However, in order to thermally decompose the binder by calcination, it is preferable to perform calcination after molding.

  In the present invention, an Nd-Fe-B-based magnet has been described as an example, but other magnets (for example, a samarium-based cobalt magnet, an alnico magnet, a ferrite magnet, and the like) may be used. In the present invention, the alloy composition of the magnet is such that the Nd component is greater than the stoichiometric composition, but may be a stoichiometric composition.

DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Motor 3 Rotor 4 Slot 5, 8 1st area 6, 9 2nd area 7, 10 3rd area 11 Stator 17 Compound 19 Green sheet 30 Molded object 31 First molded object 32 Second molded object 33 Third Molded body 35 Sintered body

Claims (11)

Permanent magnets arranged on the rotor or stator of the rotating electrical machine,
A focusing target area located at an end in the circumferential direction, and a non-focusing target area located at a central portion in the circumferential direction,
In the convergence target area, the axis of easy magnetization is oriented so as to focus on a demagnetization target area located at a circumferential end that is easily demagnetized in the convergence target area compared to other areas,
The permanent magnet for a rotating electrical machine, wherein the focusing area and the non-focusing area are integrated . 2. The permanent magnet for a rotating electric machine according to claim 1 , wherein an easy axis of magnetization is oriented in a radial direction or a parallel direction in the non-focusing target area . 3. Grinding magnet raw material into magnet powder,
Producing a mixture in which the crushed magnet powder and the binder are mixed,
Applying a magnetic field to the mixture to orient the magnetic field,
3. The permanent magnet for a rotating electric machine according to claim 1 or 2 , wherein the permanent magnet is manufactured by a step of sintering by holding a molded body of the mixture subjected to a magnetic field orientation at a firing temperature. In the magnetic field orientation step, a magnetic field is applied to the mixture, and the direction of the axis of easy magnetization is manipulated by deforming the mixture to which the magnetic field is applied into the compact, thereby performing magnetic field orientation. The permanent magnet for a rotating electric machine according to claim 3 , characterized in that: The permanent magnet for a rotating electric machine according to claim 4 , wherein in the step of orienting the magnetic field, a magnetic field is applied to the mixture in a sheet shape after the mixture is formed into a sheet shape. A rotating electrical machine, wherein the permanent magnet for a rotating electrical machine according to any one of claims 1 to 5 is arranged on a rotor or a stator. A method for manufacturing a permanent magnet disposed on a rotor or a stator of a rotating electric machine,
Grinding magnet raw material into magnet powder,
Producing a mixture in which the crushed magnet powder and the binder are mixed,
Applying a magnetic field to the mixture to orient the magnetic field,
Sintering by holding the molded body of the mixture subjected to the magnetic field orientation at a firing temperature,
Among the focusing target area located at the circumferential end provided by the permanent magnet and the non-focusing target area located at the center in the circumferential direction, in the step of magnetic field orientation, the focusing target area includes the focusing target area within the focusing target area. Orientation of the easy magnetization axis to focus on the demagnetization target area located at the circumferential end that is easily demagnetized compared to other areas ,
A method for manufacturing a permanent magnet for a rotating electrical machine, wherein the focusing target area and the non-focusing target area are integrally formed . The method for manufacturing a permanent magnet for a rotating electric machine according to claim 7 , wherein in the magnetic field orientation step, the easy axis of magnetization is oriented in a radial direction or a parallel direction in the non-focusing target area . In the magnetic field orientation step, a magnetic field is applied to the mixture, and the direction of the axis of easy magnetization is manipulated by deforming the mixture to which the magnetic field is applied into the compact, thereby performing magnetic field orientation. The method for manufacturing a permanent magnet for a rotating electric machine according to claim 7 or 8 , wherein The method for manufacturing a permanent magnet for a rotating electric machine according to claim 9 , wherein in the step of orienting the magnetic field, after the mixture is formed into a sheet, a magnetic field is applied to the mixture in a sheet. Method of manufacturing a rotary electric machine, characterized by prepared by placing a permanent magnet rotary electric machine manufactured by the method of making any of claims 7 to 10 to the rotor or stator.

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