WO2007010948A1

WO2007010948A1 - Brushless motor and rotor thereof

Info

Publication number: WO2007010948A1
Application number: PCT/JP2006/314297
Authority: WO
Inventors: Yoshinobu Honkura; Hironari Mitarai; Hiroshi Matsuoka; Daisuke Nagaya
Original assignee: Aichi Steel Corporation
Priority date: 2005-07-20
Filing date: 2006-07-19
Publication date: 2007-01-25
Also published as: JP4124215B2; JP2007028857A

Abstract

[PROBLEMS] To increase the performance of a brushless motor. [MEANS FOR SOLVING PROBLEMS] This brushless motor (19) having permanent magnets on a rotor (12) comprises a rotor (10) having grooves in which the circumferential width (a) of opening parts (16) narrower than the circumferential width (b) of the parts of the rotor on the inner sides of the opening parts and anisotropic rare-earth bond magnets (30) inserted into the grooves (20). Since a part of the outer peripheral side curved surface (32) of the anisotropic rare-earth bond magnet directly faces the teeth of a stator through a gap, the magnetic resistance of a magnetic circuit can be minimized.

Description

Brushless motor and its rotor

Technical field

TECHNICAL FIELD [0001] The present invention relates to a brushless motor in which a bond magnet is provided on a rotor, and background art relating to the rotor

Conventionally, IPM motors and SPM motors are known as brushless motors! As an IPM motor, a structure in which a rare earth sintered magnet is embedded in a rotor is known! In IPM motors, silicon steel plates are mainly used for magnetic circuits, so there is a problem that the electromagnetic noise of the motor is large because of the saliency due to the distribution of surface magnetic flux due to the change in electrical angle. . In addition, in order to reduce the eddy current loss in the silicon steel plate, it is necessary to reduce the thickness of the silicon steel plate to 0.3 mm or less. Even if this measure is taken, the eddy current loss is inferior to the SPM motor. .

[0003] As an SPM motor, a structure in which a sintered magnet is attached to the surface of a rotor is known.

Since it is necessary to form the magnet in a straw shape and attach the magnet to the rotor surface, there is a problem that the manufacturing cost increases. In addition, since sintered magnets that are easily chipped are arranged on the surface of the rotor, the surface of the magnet is covered with a stainless steel ring to prevent scattering. As a result, the air gap between the stator and the rotor becomes wider, and the motor efficiency is slightly inferior to the IPM motor. In addition, since the surface magnetic flux of the magnet is used directly, the problem of saliency does not occur, so the electromagnetic noise is small, but the axially oriented magnet is attached to the rotor surface so that the magnetic poles change alternately. In the distribution of the surface magnetic flux accompanying the change in the electrical angle, the polarity changes abruptly at the magnet junction, resulting in poor cogging torque characteristics. In addition, although the SPM motor has less eddy current loss than the IPM motor, further reduction in eddy current loss has been required as the motor output increases.

[0004] In order to solve these problems, a technique disclosed in Patent Document 1 below is known! / Speak.

Patent Document 1 below discloses an SPM motor in which a magnet is provided on the surface of a rotor. In this brushless motor, the outer periphery of the rotor is cylindrical and has a recess on the outer surface. An anisotropic rare earth bonded magnet with polar anisotropy orientation is provided, and a rare earth sintered magnet is disposed in the recess. However, in this type of rotor, scattering of rare earth sintered magnets becomes a problem. Therefore, a ring-shaped rare earth bonded magnet is in contact with the outer periphery of the rare earth sintered magnet and anisotropic rare earth bonded magnet. It is done.

Patent Document 1: JP 2004-242378 A

Disclosure of the invention

Problems to be solved by the invention

[0005] While inserting a ring-shaped rare earth bonded magnet to prevent scattering after inserting the rare earth sintered magnet into the concave portion of the cylindrical anisotropic rare earth bonded magnet, However, there is a problem that the structure and manufacturing are complicated.

The present invention has been made to solve the above-described problems, and an object of the present invention is to simplify the structure and facilitate manufacture by reducing the number of parts. Another object is to improve the output torque by making the manufacturing easier by eliminating the ring to prevent the magnets from scattering and by reducing the gap between the stator teeth. is there. Also, it is to improve the motor performance index (torque Z motor magnetic circuit component volume) and reduce the cogging torque.

Means for solving the problem

[0006] In the brushless motor in which the rotor is provided with a permanent magnet, the width taken in the circumferential direction of the opening on the side facing the armature of the rotor is the width in the circumferential direction inside the rotor. A brushless motor comprising: a rotor having a narrower groove; and a bond magnet inserted into the groove.

The shape of the groove in the cross section perpendicular to the axis of the rotor is arbitrary. The groove is opened on the side surface of the rotor, and the bonded magnet inserted into the groove is arranged so as to face the teeth of the stator directly at the opening of the groove.

[0007] The invention of claim 2 is the brushless motor according to claim 1, wherein in the rotor, a recess is formed from the outer periphery between adjacent grooves. By providing the recess, the cogging torque can be reduced. The cross-sectional shape perpendicular to the rotor axis of the recess can be any shape such as strip, slit, V-shape, etc. The

[0008] The invention of claim 3 is the brushless motor according to claim 1 or claim 2, wherein the bonded magnet is an anisotropic rare earth bonded magnet. By employing this anisotropic rare earth bond magnet, the output torque can be improved when the configuration of the present invention is employed.

[0009] The invention of claim 4 is the brushless motor according to any one of claims 1 to 3, wherein the bonded magnet is press-fitted into the groove. Since the bond magnet is elastic, it is possible to fix the bond magnet in the groove without using an adhesive by press-fitting into the rotor groove using the elasticity.

[0010] The invention according to claim 5 is an aperture in a brushless motor in which a rotor is provided with a permanent magnet, and the width taken in the circumferential direction of the opening on the side surface facing the armature of the rotor is an opening. The rotor has a groove that is narrower than the width in the circumferential direction inside the rotor, and a bond magnet is inserted into the groove. The invention according to claim 6 is the rotor according to claim 5, wherein a recess is formed from the outer periphery between adjacent grooves, and the invention according to claim 7 The bonded magnet is an anisotropic rare earth bonded magnet. The rotor according to claim 5 or 6, wherein the bonded magnet is press-fitted into the groove. The rotor according to any one of claims 5 to 7, wherein the rotor is provided. The above invention relates to a rotor used in the brushless motor according to claims 1 to 4, and the same configuration and modifications as those of the invention according to claims 1 to 4 can be adopted.

The invention's effect

[0011] In the invention of claim 1, the circumferential width of the opening of the groove is configured to be narrower than the circumferential width of the groove inside the rotor. Will not be missed. Therefore, since it is not necessary to provide a ring made of a non-magnetic material or a magnetic material to prevent scattering, the magnetic resistance does not increase, and the output torque of the motor can be improved. As in the technique of Patent Document 1 described above, the magnetic ring for preventing scattering becomes a magnetic resistance in a magnetic circuit in which a magnetic flux that passes through the stator flows. Increasing force This magnetic ring does not exist in the present invention. Therefore, the output torque of the motor can be greatly improved. Further, since the outer peripheral surface force of the bonded magnet directly faces the stator teeth with a gap therebetween, almost all the magnetic flux of the bonded magnet can be passed through the stator teeth through the gap. As a result, the output torque can be improved.

Due to the above-described effects, the present invention makes it possible to reduce the torque motor performance index (torque Z magnetic circuit component volume) can be improved. In addition, the present invention can improve torque even for IPM motors. In addition, for a motor that is prevented from scattering by the anisotropic rare earth bonded magnet of Patent Document 1, the torque per unit magnet usage (torque z magnet usage volume) is greatly improved.

[0012] The invention of claim 2 is characterized in that in the rotor, a recess is formed from the outer periphery between adjacent grooves. The cogging torque can be reduced by forming the recess.

[0013] In the invention of claim 3, since the bonded magnet is an anisotropic rare earth bonded magnet, the output torque can be improved. In the invention of claim 4, the bonded magnet is press-fitted into the groove. Since it is fixed in the groove due to the elasticity of the bond magnet, the anti-scattering ring is not necessary, and there is no substance in the magnetic circuit that reduces the magnetic resistance, so the output torque can be increased.

[0014] The inventions of claims 5 to 8 are inventions of a rotor used in the motor described above, and each exhibit the same effect as the above-described effect.

Brief Description of Drawings

FIG. 1 is a configuration diagram showing a rotor of a brushless motor according to a specific embodiment of the present invention.

FIG. 2 is a perspective view showing the shape of an anisotropic rare earth bonded magnet.

FIG. 3 is a cross-sectional view showing an anisotropic rare earth bonded magnet attached to a rotor.

FIG. 4 is a cross-sectional view showing the structure of a rotor according to another embodiment.

Explanation of symbols

[0016] 10 ... Brushless motor

12 ... Rotor core 14.

16 ·· -Opening

20

22 ·· 'Curved surface

24 ·· -Inner curved surface

30 ·· 'Anisotropic rare earth bonded magnet

32 ·· 'Curved outer surface

34 ··-Curve on the inner circumference

321… curved surface

322… Both sides curved surface

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described based on embodiments. Note that the present invention is not limited to the following embodiments.

Example 1

FIG. 1 shows a configuration of a rotor 10 of an inner rotor type brushless motor. A groove 20 having four openings 16 is provided on the outer peripheral surface 14 of a cylindrical rotor core 12 made of a magnetic laminate such as a silicon steel plate. The circumferential width a of the opening 16 of the groove 20 is narrower than the width b of the groove inside the rotor. The shape of the groove 20 on the cross section perpendicular to the axial direction has a crescent shape. That is, the groove 20 is composed of a curved surface 22 on the outer peripheral side and a curved surface 24 on the inner peripheral side, and the curved surface 24 on the inner peripheral side is formed concentrically with the outer peripheral surface 14 of the rotor iron core 12, and It is configured to be smaller than the curvature of the curved surface 22 on both sides. Due to the shape of the groove 20, the rotor iron core 12 has claws 51 and 52 formed on both sides of each groove 20. By the claws 51 and 52, the anisotropic rare earth bonded magnet 30 inserted into the groove 20 does not come off even when the port 10 rotates. An anisotropic rare earth bonded magnet 30 inserted into the groove 20 is configured as shown in FIG. That is, the shape of the cross section perpendicular to the rotor shaft is a crescent, and is composed of an outer peripheral curved surface 32 and an inner peripheral curved surface 34. The inner peripheral curved surface 34 is an outer peripheral curved surface. The central curved surface 321 is concentric with the curved surface 321, and the curved surface 34 has a smaller curvature than the curved surfaces 322 on both sides of the curved surface 32 on the outer peripheral side. The unusual rare earth bonded magnet 30 is formed in a tile shape with the cross section and crescent shape extending in the axial direction.

In addition, the motor of the present embodiment is provided with a stator having teeth on the outside of the rotor 10 with a gap therebetween. A coil is wound around the teeth.

[0020] The heterogeneous rare earth bonded magnet 30 has a maximum energy product of 14MGOe (ll lKjZm ³ ) or more, and the maximum energy product is large. Therefore, the magnetoresistance of the magnetic circuit in the case of using the present invention is large. Due to the reduction effect, motor performance is greatly improved. The anisotropic rare earth bonded magnet 30 is magnetized so that the outer peripheral surface 32 and the inner peripheral surface 34 become S poles, N poles, or the opposite magnetic poles. In the stator, the number of teeth on which the steel wire is arranged is six.

[0021] The anisotropic rare earth bonded magnet 30 has been finally mass-produced by the applicant in recent years. For example, the anisotropic rare earth bonded magnet 30 is manufactured by the manufacturing method of Japanese Patent Application Laid-Open No. 2001-76997, Japanese Patent No. 2816668, Japanese Patent No. 3060104, and International Patent Application PCTZJP03Z04532. As this anisotropic rare earth bonded magnet, those having a maximum energy product of 17 MGOe to 28 MGOe (135 KJ / m ^{3 to} 223 KJ / m ³ ) can be manufactured at present.

[0022] The anisotropic rare earth bonded magnet 30 used in the motor device of the present embodiment is configured in a tile shape in which the cross section perpendicular to the axis of Nd-Fe-B is a crescent shape. The anisotropic rare earth bond magnet 30 is a magnet that is manufactured by resin molding magnetic powder made of Nd—Fe—B and is strongly magnetized in the radial direction. As materials for anisotropic rare earth bonded magnets, Nd-Fe-B, Nd-Fe-B-based materials such as materials containing other rare earth elements such as Nd and Nd, or other additive elements are used. be able to. Furthermore, materials containing rare earth elements other than Nd, such as Sm—Fe—N-based materials, SmCo-based materials, or Nd—Fe—B-based materials, and mixed materials thereof can be used.

[0023] The anisotropic rare earth bonded magnet 30 is also called a plastic magnet. This magnet is characterized by a maximum energy product (BH) of about 5 times or more compared to conventional sintered ferrite magnets.

is there. That is, the maximum energy product (BH) of a standard sintered ferrite magnet is 3.5 MGOe max

(28KjZm ³ ), this anisotropic rare-earth bonded magnet has 17MGOe ( It has a maximum energy product of 135 Kj / m ³ ) or more.

[0024] The weight ratio of the resin in the anisotropic rare earth bonded magnet 30 was in the range of 2 W% or more and 3 W% or less. Anisotropic magnet powder and resin are supplied to a mold, and in a heated state, a magnetic field is applied for orientation, followed by compression molding.

[0025] This molded body was cured and the degree of cure of the resin was improved to 90-100%. This enhanced the bond between the magnetic powder and resin, and between the resin and resin. Next, the molded body of the anisotropic rare earth bonded magnet 30 after curing was heated at a temperature below the glass transition temperature. This heating reduces the strength of the material without breaking the bond between the magnetic powder and the resin and between the resin and the resin, that is, by softening the resin so that the anisotropic rare earth bonded magnet 30 is removed. The mechanical strength was maintained by reducing the stress exerted on the anisotropic rare earth bonded magnet 30 when the end face force of the slot was pressed into the groove 20 of the rotor 10. The anisotropic rare earth bonded magnet 30 was pressed into the groove 20 and left for a while to cool the anisotropic rare earth bonded magnet 30.

[0026] The temperature at the time of press-fitting is preferably 60 to 100 ° C. This temperature range does not deteriorate the characteristics of the anisotropic rare earth bonded magnet, in addition to magnetic powder and resin, resin and resin. It is ideal for softening the resin without breaking the bond between the two and inserting the anisotropic rare earth bonded magnet 30 into the groove 40.

In this way, as shown in FIG. 3, the outer peripheral surface 32 of the anisotropic rare earth bonded magnet 30 forms a part of the outer peripheral surface 14 of the rotor core 12. Therefore, the outer peripheral surface 32 of the anisotropic rare earth bonded magnet 30 directly faces the teeth with a gap therebetween, so that the gap can be made as narrow as possible. For example, the gap width can be 0.05 mm or more and 0.4 mm or less. Therefore, since the magnetic resistance of the magnetic circuit can be made as small as possible, almost all the magnetic flux possessed by the anisotropic rare earth bonded magnet 30 can be passed through the teeth. As a result, the ability of the anisotropic rare earth bonded magnet 30 having a large energy product can be sufficiently exerted. In other words, the torque and motor performance index (torque Z magnetic circuit component volume) is improved by attaching the magnet to the rotor surface and eliminating the anti-scatter ring for the motor that uses the anti-scatter ring on the outside. be able to. In addition, the present invention can improve the torque for the IPM motor. In addition, the amount of unit magnet used for the motor that is prevented from scattering by the anisotropic rare earth bonded magnet of Patent Document 1. Torque (torque Z magnet usage volume) is greatly improved.

[0028] The thickness of the thickest portion of the anisotropic rare earth bonded magnet 30 is set in the range of 0.7 to 3 mm. If it is thinner than 1 mm, the surface magnetic flux density is lowered by the demagnetizing field of the anisotropic rare earth bonded magnet 30, which is undesirable. If it is thicker than 3 mm, the motor performance index will decrease, which is not desirable.

[0029] As described above, the circumferential width a of the opening 16 of the groove 20 is configured to be narrower than the width of the groove inside the rotor. Therefore, the anisotropic rare earth bonded magnet inserted into the groove 20 is Even if the rotor 10 rotates, it does not come off. Therefore, since it is not necessary to provide a ring made of a non-magnetic material or a magnetic material to prevent scattering, the magnetic resistance does not increase, and the output torque of the motor can be improved. In addition, since the outer peripheral surface force of the bonded magnet directly faces the teeth of the stator with a gap therebetween, almost all the magnetic flux of the bonded magnet can be passed through the stator teeth through the gap. As a result, the output torque can be improved.

In addition, this shape allows the change in the magnetic flux between the magnetic poles to be a sliding force, thereby reducing the cogging torque. In addition, since anisotropic rare earth bonded magnets are used, the magnet powder is surrounded and electrically insulated by insulating grease, which can reduce rotor eddy current loss and improve power efficiency. It becomes possible to make it.

In addition, as shown in FIG. 4, it is desirable to form notches from the periphery of the rotor core 12 to form four recesses 60. By doing so, the cogging torque can be reduced. Therefore, most of the total magnetic flux of the anisotropic rare earth bonded magnet 30 can be guided to the teeth. As a result, the motor torque can be improved.

[0031] Further, after the weight ratio of the resin of the anisotropic rare earth bonded magnet 30 is set to 2 W% or more and 3 W% or less, compression molding is performed, and after curing treatment, the degree of curing is 90 to: LOO% The anisotropic rare earth bonded magnet 30 can be easily inserted and fixed in the groove 20 of the rotor 12 by reheating at a temperature below the glass transition point to obtain a softened state.

Industrial applicability

The present invention is effective as a high-output motor that satisfies high torque, low electromagnetic noise, low cogging torque, and low eddy current loss.

L6Z l £ / 900Zdr / 13d 6 81? 60ΐ0 / .00Ζ OAV

Claims

The scope of the claims

[1] In a brushless motor with a permanent magnet on the rotor,

On the side surface of the rotor facing the armature, the width taken in the circumferential direction of the opening is a rotor having a groove narrower than the width in the circumferential direction inside the rotor;

A bonded magnet inserted into the groove;

A brushless motor characterized by comprising:

2. The brushless motor according to claim 1, wherein in the rotor, a recess is formed from the outer periphery between adjacent grooves.

3. The brushless motor according to claim 1, wherein the bonded magnet is an anisotropic rare earth bonded magnet.

4. The brushless motor according to any one of claims 1 to 3, wherein the bonded magnet is press-fitted into the groove.

[5] In a rotor in a brushless motor having a permanent magnet on the rotor,

On the side surface of the rotor facing the armature, the width taken in the circumferential direction of the opening is

A rotor having a groove that is narrower than the opening in the circumferential direction inside the rotor, and a bond magnet is inserted into the groove.

[6] The rotor according to claim 5, wherein a recess is formed from the outer periphery between adjacent grooves.

7. The rotor according to claim 5, wherein the bonded magnet is an anisotropic rare earth bonded magnet.

8. The rotor according to any one of claims 5 to 7, wherein the bond magnet is press-fitted into the groove.