JP2008245488A - Ring-like magnet, manufacturing method therefor, and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ring-like magnet, or the like, that enhances cost benefit and productivity, and also fully suppresses the occurrence of cogging torque, or the like, when used in a motor, while maintaining a high surface magnetic flux density. <P>SOLUTION: The ring-like magnet 11 has embedded a first magnet part 21, where a plurality of anisotropic sintered magnet pieces 21a are arranged circumferentially and separately at prescribed intervals, into the cylindrical wall of a second magnet part 31, consisting of cylindrically-molded isotropic bond magnets. Each anisotropic sintered magnet piece 21a is a belt-like molded body that is molded curved so as to extend spirally in the thrust direction, along the cylindrical wall of the second magnet part 31, while having a skew angle θ. Such a ring-like magnet 11 can be integrally molded by pressurization resin-molding using an isotropic bond magnet material, after arranging a plurality of the anisotropic sintered magnet pieces 21a at prescribed positions inside a die cavity and accordingly, such a ring-like magnet can be manufactured at low cost and in a simple manner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ring magnet, a manufacturing method thereof, and a motor including the ring magnet.

  Conventionally, gap magnetic flux density is used for applications such as spindle motors and voice coil motors for hard disk drive rotation of hard disk drives, motors for electric power steering of automobiles, servo motors for machine tools, vibrator motors for mobile phones, and printer motors. Surface permanent magnet motors (SPM motors), which have the advantages of being easy to increase and generating less noise, are widely used. A ring-shaped magnet having a multipolar structure in which a plurality of magnetic poles are formed on the outer peripheral surface of the rotor is usually incorporated in the SPM motor.

  As the multipolar structure of the ring-shaped magnet, for example, a radial anisotropic structure in which the ring-shaped magnet is magnetized in the radial direction (radial direction), or an arc magnetized so as to connect the magnetic poles on the outer surface of the ring-shaped magnet. A polar anisotropic structure or the like that is oriented anisotropically is known. In addition, as the magnet material, for example, a bonded magnet formed by solidifying magnet powder with a resin, a sintered magnet formed by sintering magnet powder, and the like are used. In recent years, Nd-Fe-B rare earth sintered magnets have attracted attention because they can realize high magnetic properties. For example, in the field of home appliances and industrial machinery, the conventional ferrite magnets Replacement with Nd—Fe—B-based rare earth sintered magnets is progressing, and the demand tends to increase more and more.

  SPM motors used for this type of application are rapidly being improved in performance as the size and thickness of the SPM motors are reduced, and the ring-shaped magnets mounted on the motors are also reduced in size in response to these demands. At the same time, further improvements in magnetic properties such as surface magnetic flux density (Br) and manufacturability are eagerly desired.

  In order to meet such a demand, for example, Patent Document 1 discloses that the surface magnetic flux density and the process tolerance at the time of magnetization are improved by a two-layer structure of an outer layer having radial anisotropy and an inner layer having magnetic isotropy. A ring-shaped resin magnet intended to be described is described.

  On the other hand, motors with a sufficiently reduced torque ripple including cogging torque, etc., are particularly desired for applications in which reduction of rotation unevenness, noise, or vibration is important. For example, in some cases, cogging torque (pulsation torque) is desired. In some cases, a motor having a torque characteristic that is suppressed to 1% or less of the rated torque may be required. As one of the effective methods for suppressing the cogging torque and reducing the torque ripple in this way, skew magnetization is performed in which the magnetic poles are formed obliquely with respect to the axial direction.

  By the way, in the surface permanent magnet type synchronous motor (SPMSM) using such a ring-shaped magnet, in order to realize high efficiency and high output, the magnetomotive force generated by the magnet is distributed in a sine wave shape and excited by a sine wave current. So-called sinusoidal drive is often used. When this sine wave drive is used in the AC multiphase system, torque of each phase that changes sinusoidally with respect to the angle is superimposed, a constant output is obtained, and in principle, no torque ripple occurs (in practice, Due to the static and dynamic characteristics of the motor, periodic torque fluctuations will inevitably occur.)

  On the other hand, the radial anisotropic ring-shaped magnet described in Patent Document 1 is difficult to magnetize sinusoidally compared to a polar anisotropic magnet, and the magnetic flux density of one pole in the circumferential direction. Since the distribution shape approximates a steep trapezoid and has a characteristic that the magnetic flux density of the upper side edge of the trapezoid protrudes, the magnetomotive force generated by the magnet becomes a sine wave required by sine wave drive Distribution, that is, realization of a sinusoidally changing magnetic flux waveform tends to be difficult. Then, the magnetic flux waveform of the ring-shaped magnet and the current phase waveform in the sine wave drive do not match, and a relatively large torque ripple occurs. In order to alleviate this, although a slight sinusoidal magnetization can be performed by adjustment magnetization that adjusts the applied magnetic field at the time of magnetization, there is a limit, and in the conventional radial anisotropic ring magnet described above, However, it is difficult to sufficiently reduce the cogging torque and the torque ripple only by the skew magnetization described above.

In order to improve this, for example, in Patent Document 2, a plurality of anisotropically oriented rings are stacked in the axial direction, and notches are periodically formed in the ring at regular intervals. The shape of the magnetic flux density distribution for one pole in the direction is changed from a trapezoid, and the positions of these notches are shifted by a predetermined rotation angle in the circumferential direction between the rings, so that a pseudo skew is formed to form cogging torque and A radially anisotropic sintered ring-shaped magnet intended to reduce torque ripple is described.
Japanese Patent Laid-Open No. 01-031401 Japanese Patent Laying-Open No. 2005-065455

  However, in the ring-shaped magnet described in Patent Document 2, the amount of magnet at the notch is relatively small, so that the magnetic flux density at that portion is reduced, and the rectangular (trapezoidal) shape of the magnetic flux density distribution changes to a stepped shape. However, there is still a limit to magnetizing a sinusoidal shape, and it is difficult to realize a magnetic flux waveform that changes sinusoidally as required by sinusoidal driving. In addition, since the upper and lower rings are arranged in steps with a predetermined angle shift, the skew is only pseudo, and its effect is insufficient. Therefore, even with such a ring-shaped magnet, the effect of reducing cogging torque and torque ripple is still insufficient.

  In addition, the sintered magnet is generally expensive among various magnets, and the ring-shaped magnet described in Patent Document 2 uses a sintered magnet over the entire circumference of the ring. The amount of sintered magnet used was large, and therefore it was expensive. Furthermore, since this ring-shaped magnet has a plurality of rings and notches, the number of parts increases, and high-precision positioning is required when assembling the rotor, which complicates the manufacturing process. It was.

  Furthermore, sintered magnets have the property of shrinking greatly during the sintering, and in particular, when shaped into a ring shape and sintered in a radial orientation like a sintered ring magnet, the dimensional accuracy is sufficiently secured. The shape after sintering is slightly larger than the target dimension, and the extremely hard sintered magnet is often ground and polished, resulting in poor productivity. There was a face. In addition, this grinding and polishing process requires extremely high dimensional accuracy (for example, a radial tolerance of about several tens of μm may be required for a ring-shaped magnet having a thickness of 3 mm). The processing cost is extremely increased, and cracks due to external pressure applied during processing, internal cracks, and the like are generated, and the yield may be deteriorated.

  Therefore, the present invention has been made in view of such circumstances, and while maintaining a high surface magnetic flux density, the generation of cogging torque and torque ripple when used as a motor is sufficiently suppressed to improve torque characteristics. Provided are a ring-shaped magnet that has a simple structure, can be manufactured at a reduced cost, and can be economically and productive, a method for manufacturing the same, and a motor including the ring-shaped magnet. With the goal.

  In order to solve the above problems, a ring-shaped magnet according to the present invention includes a first magnet portion having a plurality of anisotropic sintered magnet pieces disposed at predetermined intervals in the circumferential direction, and a plurality of anisotropic shapes thereof. 2nd magnet part which has an isotropic bonded magnet arrange | positioned (intervened) between each of the property sintered magnet pieces. In the present invention, the “ring shape” includes not only a short annular body but also a cylindrical annular body having a certain height, and is preferably a perfect circle or a substantially perfect circle.

  In such a configuration, a plurality of magnetic poles are formed in the circumferential direction of the ring-shaped magnet by the anisotropic sintered magnet pieces of the first magnet portion being spaced apart at a predetermined interval, and these anisotropic sintered pieces are formed. By arranging the magnet pieces so that the polarities are alternately different along the circumferential direction, a ring-shaped magnet having a magnetic flux waveform whose polarity periodically changes is formed. And since the 2nd magnet part which has an isotropic bond magnet interposes between the anisotropic sintered magnet pieces which form a magnetic pole in this way, an anisotropic sintered magnet is located in the center part of a magnetic pole. A relatively high sufficient surface magnetic flux density can be applied by the strip, and a relatively low surface magnetic flux density can be applied to the boundary between the magnetic poles by the isotropic bonded magnet.

  That is, since the anisotropic sintered magnet piece is not processed, a portion having a low surface magnetic flux density is formed between the magnetic poles having a high surface magnetic flux density along the circumferential direction of the ring-shaped magnet. When magnetizing, the shape of the magnetic flux density distribution for one pole in the circumferential direction is changed from a trapezoid (rectangular) unique to a conventional radial anisotropic magnet like Patent Document 1 to a polar anisotropic magnet. Easy to adjust to sine wave. In other words, in a ring-shaped magnet using a conventional radial anisotropic sintered magnet, the surface magnetic flux density changes hard (steeply) at the circumferential edge of the magnetic pole, whereas in the present invention, A surface magnetic flux density distribution in which the surface magnetic flux density changes softly (slowly) at the circumferential edge of the magnetic pole is easily realized. That is, in the present invention, sinusoidal magnetization, which was difficult with a conventional radial anisotropic magnet, is inherently easily and reliably compensated for by the presence of the first magnet portion and the second magnet portion.

  In addition, the second magnet part has a ring shape, and at least a part, preferably all, of the first magnet part is embedded (embedded) in the peripheral wall of the second magnet part. It is preferable that it is. In this way, when the first magnet part is fixedly held by the second magnet part, and the entire first magnet part is embedded in the second magnet part, the first magnet part is It is protected from the external environment by the second magnet part. At this time, if the second magnet part is formed of an isotropic bonded magnet material that is a fluid, the anisotropic sintered magnet pieces of the first magnet part are arranged at a predetermined interval, and between them. By casting an isotropic bonded magnet material, the ring-shaped magnet is simply formed by molding.

  Furthermore, it is more preferable if the anisotropic sintered magnet piece has a strip shape and extends in the thrust direction along the peripheral wall of the ring-shaped magnet. Since such an anisotropic sintered magnet piece can be formed by a simple band-shaped molded body, it is easy to mold and process itself, and the first magnet portion can be assembled in the circumferential direction. It becomes simple. The “thrust direction” refers to a direction along the extending direction of the virtual central axis of the ring-shaped magnet, and may extend straight, for example, in a spirally twisted state. May be.

  Furthermore, it is preferable that the anisotropic sintered magnet piece has a strip shape because a desired and effective skew can be provided. That is, it is more preferable that the anisotropic sintered magnet piece has a skew angle.

  Furthermore, it is useful that the anisotropic sintered magnet piece has a polygonal cross section and the opposite ridge angle (vertical angle) in the cross section is chamfered. By doing so, there are advantages such that the surface magnetic flux density distribution of the ring-shaped magnet can be made closer to a sine wave shape and the die-cutting at the time of molding becomes easy.

  In addition, a motor according to the present invention includes the ring-shaped magnet of the present invention, is provided with a stator having a plurality of coils arranged in the circumferential direction, and is rotatably provided in the stator. A first magnet portion having a plurality of anisotropic sintered magnet pieces arranged at predetermined intervals in the circumferential direction. And the 2nd magnet part which has an isotropic bonded magnet arrange | positioned between each of several anisotropic sintered magnet pieces is provided.

  Furthermore, the manufacturing method of the ring-shaped magnet according to the present invention is a method for effectively manufacturing the ring-shaped magnet of the present invention, and a plurality of anisotropic sintered magnet pieces are formed in a ring shape in a cavity of a mold. And a preparatory step of supplying an isotropic bonded magnet material between each of the plurality of anisotropic sintered magnet pieces, and a plurality of anisotropic sintered magnet pieces. And forming a ring-shaped molded body by molding (or pressurizing and / or heating) an isotropic bonded magnet material, and a magnetization process for applying a magnetic field to the ring-shaped molded body and magnetizing the ring-shaped molded body And have. At this time, in the preparation step, it is more preferable to dispose a composite body in which a plurality of anisotropic sintered magnet pieces are disposed at a predetermined interval on a cylindrical sheet member in a cavity of a mold.

  According to the ring-shaped magnet of the present invention, the manufacturing method thereof, and the motor including the ring-shaped magnet, the magnetic flux density distribution of the ring-shaped magnet is sine with a simple configuration including the first magnet portion and the second magnet portion. Since it is easy to adjust to a wave shape, when used in a motor, cogging torque and torque ripple can be reduced easily at low cost, and the degree of freedom in design can be increased. In addition, the amount of sintered magnets used and the number of parts can be reduced, and the processing cost can be greatly reduced, the manufacturing process can be simplified, and the yield can be improved. Economic efficiency and productivity can be improved.

  Embodiments of the present invention will be described below. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. The following embodiments are examples for explaining the present invention, and the present invention is not limited only to the embodiments.

(First embodiment)
FIG. 1 is a longitudinal sectional view schematically showing a configuration of a preferred embodiment of a motor according to the present invention. The motor 1 is provided with a cylindrical stator 4 and a columnar inner rotor 5 (rotor) in a housing 2. The stator 4 includes a plurality of coils 4a arranged at predetermined intervals in the circumferential direction inside the cylindrical wall (peripheral wall), and a slot is constituted by these coils 4a. In the present embodiment, the stator 4 is provided with 9 slots (not shown).

  Further, bearings 2a and 2a are provided on the upper wall and the bottom wall of the housing 2, and a rotating shaft 3 penetrating the stator 4 is supported by the bearings 2a and 2a. In the inner rotor 5, the rotation shaft 3 is fixed so as to pass through the center of the cross section in the figure, and is provided so as to be rotatable in the space in the stator 4 together with the rotation shaft 3. The inner rotor 5 is a cylindrical ring-shaped magnet 11 provided on the outer peripheral wall of a columnar rotor core 6 (iron core) made of iron or the like.

  FIG. 2 is a perspective view showing a schematic configuration of the ring-shaped magnet 11, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. The ring-shaped magnet 11 has a multipolar structure in which a plurality of magnetic poles are formed in the circumferential direction, and is composed of eight anisotropic sintered magnet pieces 21 a supported by a cylindrical sheet member 41. The first magnet portion 21 is embedded in the cylindrical wall (thickness Δt) of the second magnet portion 31 formed of an isotropic bonded magnet formed in a cylindrical shape having a substantially circular (circular) cross section. It has been done. Thus, the isotropic bonded magnets of the second magnet part 31 are arranged between the anisotropic sintered magnet pieces 21a of the first magnet part 21, and furthermore, these anisotropic sintered magnets. The piece 21a (the entire first magnet portion 21) is covered with the second magnet portion.

  The plurality of anisotropic sintered magnet pieces 21a are arranged at equal intervals along the outer peripheral surface of the sheet member 41 at a predetermined interval Δs. The adjacent anisotropic sintered magnet pieces 21a are provided so as to have different polarities, so that the surface magnetic flux density of the ring-shaped magnet 11 periodically changes along the outer periphery. It is configured. The outer peripheral surface and inner peripheral surface of the ring-shaped magnet 11 (the outer wall surface 31a and the inner wall surface 31b of the second magnet portion 31 respectively) are smooth curved surfaces that are substantially free of unevenness over the entire periphery.

  4 and 5 are a perspective view and a front view, respectively, schematically showing the anisotropic sintered magnet piece 21a. Each anisotropic sintered magnet piece 21a is a substantially C-shaped curved strip-shaped molded body having a curvature in the illustrated horizontal cross section (transverse cross section), and more specifically, on the cylindrical wall of the second magnet portion 31. A curved shape is formed so as to spirally extend in the thrust direction along the thickness and the thickness Δd and the width Δw are constant over the entire length. Each anisotropic sintered magnet piece 21a has a skew angle θ (an angle formed by the central axis of the ring-shaped magnet 11, that is, the rotating shaft 3 and the anisotropic sintered magnet piece 21a in plan view). It is installed. The skew angle θ is appropriately set according to the diameter of the ring-shaped magnet 11, the length in the thrust direction of the anisotropic sintered magnet piece 21a, the number of slots and the number of poles of the motor 1, etc. The case where the angle θ is about 20 ° is illustrated.

  Here, FIG. 6 is a view corresponding to a cross-sectional view (partially omitted) taken along the line VI-VI in FIG. 5, and the magnetization direction of the anisotropic sintered magnet piece 21 a when sinusoidal magnetization is performed. It is a figure which shows (illustrated solid line arrow) notionally.

  Here, as a magnet material of the anisotropic sintered magnet piece 21a, a rare earth sintered magnet of RBT system (R: one or more of rare earth elements, T: Fe, B: boron), particularly Nd. A Fe—B rare earth sintered magnet is preferably used.

  The second magnet portion 31 is obtained by magnetizing an isotropic bonded magnet containing magnetic powder in a resin binder. In the ring-shaped magnet 11, the magnetic flux density distribution has a sine wave shape. To compensate for this. As the magnet powder of the isotropic bonded magnet of the second magnet portion 31, a rare earth sintered magnet powder of RBT system (R: one or more of rare earth elements, T: Fe, B: boron), In particular, Nd—Fe—B rare earth sintered magnet powder is preferably used. A conventionally known resin binder can be appropriately selected and used.

  An example of a method for manufacturing the ring-shaped magnet 11 configured as described above will be described below.

  First, a mold in which a cavity (internal space) having the same shape as the outer shape of the second magnet part 31 is defined is prepared, and in the cavity, eight anisotropic sintered magnet pieces 21a are arranged in the circumferential direction. An isotropic bonded magnet material (for example, a compound) containing magnetic powder in a resin binder with the anisotropic sintered magnet piece 21a being held at a predetermined interval Δs and spaced at equal intervals. Is supplied into the cavity (preparation step). Next, an isotropic bonded magnet material is molded and solidified by pressurizing the inside of the cavity at an appropriate pressure and temperature, thereby ring-shaped molding in which the anisotropic sintered magnet piece 21a is embedded in the isotropic bonded magnet. Form the body (molding process). Thereafter, an appropriate magnetic field is applied to the obtained ring-shaped molded body, and magnetization is performed while adjusting the magnetic field as necessary to obtain the ring-shaped magnet 11 (magnetization step).

  Here, FIG. 7 is a perspective view showing an example of a state in which the anisotropic sintered magnet pieces 21a are arranged at equal intervals in the circumferential direction in the preparation step. As shown in FIG. 7, in the preparation step, for example, anisotropic sintered magnet pieces 21 a are arranged on the outer peripheral surface of a cylindrical sheet member 41 at regular intervals Δs in the circumferential direction and bonded. The composite 51 thus prepared can be produced and placed at a predetermined position in the cavity of the mold. For example, the composite 51 is easily manufactured by arranging and bonding the anisotropic sintered magnet piece 21a at a predetermined position on the sheet member 41, and then rolling it into a cylindrical shape to hold the shape. can do.

  In the above magnetizing step, according to a conventional method, a ring-shaped molded body is placed in a desired magnetic field using a magnetizing power source or a magnetizing yoke, and the outer peripheral surface of the ring-shaped molded body is magnetized. Magnetize as follows. Here, by adjusting the magnetization waveform (adjustment magnetization), the magnetic flux density distribution is changed from a rectangular wave shape peculiar to the magnetized structure of the anisotropic magnet to a substantially ideal sine wave shape. It is easy to adjust. Specifically, the magnetization waveform is adjusted so that the combined magnetic flux density of the second magnet portion 31 made of the anisotropic sintered magnet piece 21a and the isotropic bonded magnet has a sinusoidal magnetic flux density distribution. . At that time, it is preferable to perform adjustment magnetization using skew magnetization together. An example of the surface magnetic flux density distribution in the ring-shaped magnet 11 obtained by magnetization in this way is shown in FIG.

  FIG. 8 shows a magnetic flux density distribution (solid line connecting white circles) of one pole in the circumferential direction (one anisotropic sintered magnet piece 21a and its peripheral portion) in the ring-shaped magnet 11, and a conventional radial anisotropy. Is a graph showing a simulation result of a magnetic flux density distribution (solid line connecting white square marks) for one circumferential direction in a ring-shaped magnet using only a sintered magnet, the horizontal axis indicates the angular position, and the vertical axis indicates The surface magnetic flux density is indicated in arbitrary units (au). From this result, it is understood that the ring-shaped magnet 11 according to the present invention can obtain a sinusoidal magnetic flux density distribution.

  According to the motor 1 including the ring-shaped magnet 11 according to the present invention configured as described above, the second is formed of an isotropic bonded magnet between the anisotropic sintered magnet pieces 21a forming the magnetic pole. By interposing the magnet portion 31, a higher surface magnetic flux density can be applied to the central portion of the magnetic pole, while a lower surface magnetic flux density can be applied to the boundary portion between the magnetic poles. In addition, the shape of the magnetic flux density distribution for one pole in the circumferential direction can be easily adjusted to a sine wave shape as compared with a ring-shaped magnet using only a conventional radial anisotropic magnet. That is, according to the ring-shaped magnet 11, since the first magnet portion 21 and the second magnet portion 31 are provided, sinusoidal magnetization, which has been difficult in the past, can be inherently easily and reliably performed. Thus, a sinusoidal surface magnetic flux density distribution in which the surface magnetic flux density changes softly at the circumferential edge of the magnetic pole can be realized. Therefore, it is possible to realize a magnetic flux waveform that changes sinusoidally as required by the sine wave drive in the motor 1, and thereby it is possible to significantly reduce the occurrence of cogging torque and torque ripple. Torque characteristics can be improved.

  In addition, since the ring-shaped magnet 11 does not use a relatively expensive sintered magnet over the entire circumference, the material cost of the sintered magnet can be reduced, and the ring described in Patent Document 2 can be used. Since the number of parts can be reduced as compared with the magnets, the economy can be improved.

  Furthermore, since each anisotropic sintered magnet piece 21a is configured by a belt-shaped molded body that spirally extends in the thrust direction along the cylindrical wall of the second magnet portion 31 and has a skew angle θ, Patent Document 2 The original skew magnetization can be performed instead of the pseudo skew magnetization described in the above, and thereby the cogging torque and the torque ripple can be further reduced. In addition, since the anisotropic sintered magnet piece 21a is composed of a simple band-shaped molded body in this way, manufacturing is simplified and the cost is reduced, and the assembly process can be simplified. As a result, it is possible to further improve economic efficiency and productivity.

  Furthermore, since the second magnet portion 31 is formed in a cylindrical shape and the anisotropic sintered magnet piece 21a is embedded in the second magnet portion 31, the cylindrical rotor core is assembled when the inner rotor 5 is assembled. 6 can be easily mounted with a cylindrical ring-shaped magnet 11. Therefore, the manufacturing process can be simplified and the number of parts can be reduced, so that further cost reduction and productivity improvement can be realized.

  Furthermore, since the outer surface of the ring-shaped magnet 11 is composed of an isotropic bonded magnet that is softer than the sintered magnet by embedding the anisotropic sintered magnet piece 21 a in the second magnet portion 31, Grinding and polishing required for the ring-shaped magnet using the sintered magnet is not required or is simplified. Therefore, the processing cost can be further reduced. Accordingly, the degree of freedom in designing the outer shape of the ring-shaped magnet 11 can be increased, and the damage to the ring-shaped magnet due to the application of external pressure in grinding and polishing can be suppressed, thereby reducing the yield and reducing the productivity. Can be further improved.

  Furthermore, since the anisotropic sintered magnet piece 21a is embedded in the second magnet portion 31, and the entire anisotropic sintered magnet piece 21a is covered with the second magnet portion 31, depending on the external environment. While it can suppress that the magnetic characteristic of the anisotropic sintered magnet piece 21a deteriorates, corrosion resistance can be improved and the reliability of a product can be increased. In other words, it is possible to omit the surface treatment of the anisotropic sintered magnet piece 21a in order to impart corrosion resistance, and further simplification and cost reduction of the manufacturing process can be achieved.

  Furthermore, since the ring-shaped magnet 11 can be manufactured simply and in a short time by only one molding process such as pressure molding using a mold, it is also excellent in economy and productivity. In addition, since the composite in which the anisotropic sintered magnet piece 21a is arranged on the sheet member 41 is used, the arrangement state of the anisotropic sintered magnet piece 21a can be reliably maintained, and the manufacturing accuracy can be improved. Is possible. Therefore, it is possible to reduce the occurrence of cogging torque and torque ripple of the motor 1 due to the shape factor such as the deviation of the magnetic pole position caused by the variation in the position of the anisotropic sintered magnet piece 21a.

(Second Embodiment)
FIG. 9 is a perspective view showing a schematic configuration of another embodiment of the ring-shaped magnet according to the present invention. The ring-shaped magnet 61 is replaced with the 1st magnet part 21 comprised from the 8 anisotropic sintered magnet pieces 21a, and the 1st magnet comprised from the 12 anisotropic sintered magnet pieces 71a. Except for the provision of the portion 71 and the omission of the sheet member 41, the ring-shaped magnet 11 shown in FIG.

  The plurality of anisotropic sintered magnet pieces 71a are spaced apart at equal intervals Δs in the circumferential direction, and the first magnet portion 71 is configured from these anisotropic sintered magnet pieces 71a. Yes. Moreover, the adjacent anisotropic sintered magnet pieces 71a are provided so that the polarities are different from each other, so that the surface magnetic flux density of the ring-shaped magnet 61 periodically changes along the outer periphery. It is configured. Each anisotropic sintered magnet piece 71a is a strip-shaped molded body (plate-shaped body) in which the illustrated horizontal section (transverse section) forms a rectangular shape (rectangular shape), and more specifically, the second magnet section 31. Thus, the anisotropic sintered magnet pieces 71a do not have a skew angle θ, and are formed so as to extend straight along the cylindrical wall in the thrust direction.

  Here, FIG. 10 is a diagram corresponding to a cross-sectional view (partially omitted) along the line XX in FIG. 9, and the magnetization direction of the anisotropic sintered magnet piece 71 a when sinusoidal magnetization is performed. It is a figure which shows (illustrated solid line arrow) notionally.

  According to the ring-shaped magnet 61 configured in this way, in addition to the operational effects (excluding the operational effects due to the skew angle θ) produced by the motor 1 including the above-described ring-shaped magnet 11, the anisotropic sintered magnet piece 71a is provided. Since it is formed with a simpler plate-like body than the anisotropic sintered magnet piece 21a, the manufacturing cost of the member can be further reduced, and the handleability is improved at the time of operation. In addition, productivity can be further improved. Furthermore, since the anisotropic sintered magnet piece 71a is arranged in a straight line in the axial direction (that is, the skew angle θ is 0), the arrangement of the anisotropic sintered magnet piece 71a at the time of assembly is simplified, and the manufacturing accuracy is further improved. Can be increased. Therefore, it is possible to reduce the occurrence of cogging torque and torque ripple of the motor 1 due to the shape factor such as the deviation of the magnetic pole position caused by the variation in the position of the anisotropic sintered magnet piece 71a.

  In addition, as above-mentioned, this invention is not limited to said each embodiment, In the range which does not deviate from the summary, it can add suitably. For example, the number of slots and the number of poles of the stator 4 and the ring-shaped magnets 11 and 61 can be appropriately set according to required characteristics and the like, for example, appropriately selected from combinations of 2 to 40 poles and 3 to 48 slots Examples of combinations of the number of poles and the number of slots that can reduce the cogging torque include, for example, the 8-pole 9-slot, the 10-pole 9-slot, the 10-pole 12-slot, and the 14-pole 12-slot exemplified in the first embodiment. Here, a suitable skew angle θ varies depending on the number of poles and the number of slots. For example, in the case of 14 poles and 12 slots, a preferable skew angle θ is 12 °. In addition, the first magnet portions 21 and 71 may not all be embedded in the second magnet portion 31 or may be partially embedded. For example, the first magnet portions 21 and 71 may be embedded by the second magnet portion. Only the outer peripheral surface of the magnet part may be covered.

  Further, the anisotropic sintered magnet pieces 21a and 71a may have a polygonal cross section (horizontal cross section in the drawing), and a curved surface having a curvature R may be formed by chamfering opposing ridge angles in the cross section. Here, FIG. 11 is a schematic cross-sectional view showing anisotropic sintered magnet pieces 21a and 71a having a polygonal cross-section and having curved surfaces having a curvature R by chamfering opposing ridge angles in the cross-section. As illustrated, curved surfaces R having a curvature of, for example, about 0.2 to 1.5 are formed at opposing ridge angles (vertical angles) X1 and X1 of the anisotropic sintered magnet pieces 21a and 71a. With this configuration, the concentration of magnetic flux at the end can be reduced, so that the surface magnetic flux density distribution of the ring-shaped magnets 11 and 61 can be made closer to a sine wave shape, and die cutting during molding can be performed. It becomes easy and productivity can be improved more.

  Further, the opposing ridge angles X2 and X2 in FIG. 11 may be chamfered to form a curved surface. In this case, the curved surface R may or may not be formed at the opposing ridge angles X1 and X1. Furthermore, for example, the anisotropic sintered magnet piece 71a may be an arcuate body. FIG. 12 is a cross-sectional view showing such an arc-shaped anisotropic sintered magnet piece 71a. In this way, the press direction and the magnetic field direction can be made perpendicular (the left-right direction in the figure is the magnetic field direction (orientation direction) and the direction perpendicular to the paper surface is the press direction), so that the orientation can be increased, and as a result, the magnetic flux density can be increased. It can be further increased.

  Furthermore, you may make it comprise the anisotropic sintered magnet piece 21a, 71a from a some molded object. For example, a plurality of anisotropic sintered magnet pieces may be arranged in the thickness direction of the diameter of the cylindrical wall having the thickness Δt of the second magnet portion 31. Furthermore, the anisotropic sintered magnet pieces 21a and 71a may be formed of a non-molded body in which sintered magnet fine pieces, particles and / or granules are aggregated. For example, the magnet piece may be configured by filling a fine plate, particles and / or granules of a sintered magnet into a hollow plate-like body having the same outer shape as the anisotropic sintered magnet pieces 21a and 71a. . In addition, an uneven portion or a notch portion may be provided on the outer wall surface 31 a and / or the inner wall surface 31 b of the second magnet unit 31. In the present invention, since the second magnet portion 31 is formed from an isotropic bonded magnet that is easy to process, the processing of the outer shape is extremely easy and the processing accuracy can be increased, so that desired magnet characteristics can be obtained. The ring-shaped magnet which has can be obtained simply.

  As described above, according to the ring-shaped magnet and motor of the present invention and the motor provided with the ring-shaped magnet, torque characteristics can be obtained by sufficiently suppressing the occurrence of cogging torque and torque ripple while maintaining a large surface magnetic flux density. In addition, since it has a simple structure and the manufacturing cost is reduced and the economy and productivity can be increased, the general use of ring-shaped permanent magnets, and the SPM motor equipped with the same, etc. It can be used widely and effectively in general motors and various devices, facilities, systems, and the like equipped with them.

1 is a longitudinal sectional view schematically showing a configuration of an embodiment of a motor according to the present invention. 2 is a perspective view showing a schematic configuration of a ring-shaped magnet 11. FIG. It is sectional drawing which follows the III-III line of FIG. It is a perspective view which shows the anisotropic sintered magnet piece 21a schematically. It is a front view which shows roughly the anisotropic sintered magnet piece 21a. (A) And (B) is a figure equivalent to sectional drawing which follows the VI-VI line in FIG. 5, and is a figure which shows notionally the magnetization direction of the anisotropic sintered magnet piece 21a. It is a perspective view which shows an example of the state which has arrange | positioned the anisotropic sintered magnet piece 21a at equal intervals in the circumferential direction in a preparatory process. It is a graph which shows the simulation result of the magnetic flux density distribution for the circumferential direction 1 pole in the ring-shaped magnet 11, and the magnetic flux density distribution for the circumferential direction 1 pole in the ring-shaped magnet using only the conventional radial anisotropic sintered magnet. . It is a perspective view which shows schematic structure of other embodiment of the ring-shaped magnet by this invention. (A) And (B) is sectional drawing (a part is abbreviate | omitted) in alignment with the XX line in FIG. 9, and is a figure which shows notionally the magnetization direction of the anisotropic sintered magnet piece 71a. It is a schematic sectional drawing which shows the anisotropic sintered magnet piece 21a and 71a which comprised the cross-sectional polygon, and the curved surface which has the curvature R was formed by chamfering the opposing ridge angle in the cross section. It is sectional drawing which shows the anisotropic sintered magnet piece 71a which makes this bow shape.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Housing, 2a ... Bearing, 3 ... Rotating shaft, 4 ... Stator, 4a ... Coil, 5 ... Inner rotor (rotor), 6 ... Rotor core, 11 ... Ring-shaped magnet, 21, 71 ... 1st Magnet part, 31a ... outer wall surface, 31b ... inner wall surface, 21a, 71a ... anisotropic sintered magnet piece, 31 ... second magnet part, 41 ... sheet member, 51 ... composite, θ ... skew angle, R ... Curvature, X1-X1, X2-X2 ... Opposing ridge angle.

Claims (7)

A first magnet portion having a plurality of anisotropic sintered magnet pieces arranged at predetermined intervals in the circumferential direction;
A second magnet portion having an isotropic bonded magnet disposed between each of the plurality of anisotropic sintered magnet pieces;
A ring-shaped magnet comprising: The second magnet part has a ring shape,
The first magnet part is one in which at least a part of the first magnet part is embedded in the peripheral wall of the second magnet part.
The ring-shaped magnet according to claim 1. The anisotropic sintered magnet piece has a band shape and extends in the thrust direction along the peripheral wall of the ring-shaped magnet.
The ring-shaped magnet according to claim 1 or 2. The anisotropic sintered magnet piece has a skew angle.
The ring-shaped magnet according to claim 3. The anisotropic sintered magnet piece has a polygonal cross section, and the opposite ridge angle in the cross section is chamfered.
The ring-shaped magnet according to claim 4. A stator having a plurality of coils arranged in the circumferential direction;
A rotor having a rotor core provided rotatably in the stator and provided with a ring-shaped magnet; and
The ring-shaped magnet includes a first magnet portion having a plurality of anisotropic sintered magnet pieces arranged at predetermined intervals in the circumferential direction, and each of the plurality of anisotropic sintered magnet pieces. Comprising a second magnet portion having an isotropic bonded magnet disposed therebetween,
motor. A plurality of anisotropic sintered magnet pieces are arranged in a ring shape and at a predetermined interval in the circumferential direction in the cavity of the mold, and isotropic between the plurality of anisotropic sintered magnet pieces. A preparatory process for supplying a conductive bond magnet material;
Forming a plurality of anisotropic sintered magnet pieces and the isotropic bonded magnet material to form a ring-shaped formed body; and
A magnetization step of applying a magnetic field to the ring-shaped molded body and magnetizing it;
The manufacturing method of the ring-shaped magnet which has this.

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