JP2009219312A - Rotating electric machine and spindle unit using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating electric machine that ensures magnet holding at the time of high-speed rotation, while delivering sufficient torque. <P>SOLUTION: The permanent magnet type rotating electric machine has a stator and a rotor. The rotor is configured in such a manner that many holding holes axially extending toward a surface part at the radial outside in opposition to the stator along the circumferential direction are formed on a rotor body made of materials with low magnetic permeability, and many permanent magnets are inserted into the holding holes. As an arrangement of the permanent magnets in the circumferential direction, a hull-back arrangement is employed wherein the permanent magnets are separated from one another. The rotating electric machine ensures magnet holding at the time of high-speed rotation, while delivering sufficient torque. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotating electrical machine and a spindle unit using the same, and more particularly to a permanent magnet type rotating electrical machine and a spindle unit using the same.

  Permanent magnet type synchronous motors (hereinafter referred to as PM motors) are composed of an SPM (Surface Permanent Magnet) motor in which permanent magnets are disposed on the outer peripheral surface of the rotor and an IPM (Interior Permanent Magnet) disposed in the interior. Broadly divided into motors.

In the SPM motor, since the permanent magnet is disposed on the outer peripheral surface of the rotor, the inductance is reduced, a high-speed current response is obtained, and the linearity of the torque is good. However, when rotating at high speed with an SPM motor, a large centrifugal force acts on the permanent magnets arranged on the outer peripheral surface, so that the permanent magnets are securely fixed to the rotor so that the permanent magnets do not fall off or be damaged by the centrifugal force. Must. In the SPM motor having such characteristics, the following representative examples can be given as a method for fixing the permanent magnet disposed on the outer peripheral surface of the rotor.
(1) Method of bonding a permanent magnet using an adhesive (2) Method of fixing using a presser fitting (3) Method of fixing with a wedge-shaped groove formed on the outer peripheral surface of a rotor shaft (4) Using a SUS tube Fixing method (5) Fixing method with CFRP ring

  However, the fixing method according to (1), (2), and (3) is suitable for high-speed rotation because the strength of the permanent magnet itself is insufficient with respect to the large centrifugal force intensity acting on the permanent magnet or the like by high-speed rotation of the rotor. Not. In the methods (4) and (5), since the SUS pipe or the CFRP ring and the rotor core back, which is a high magnetic permeability material, are separate members, there is a problem that the number of parts increases and the number of assembly steps increases.

  As a solution to these problems, it has been proposed to use an IPM motor in which a permanent magnet is embedded in the rotor. By using an IPM motor, the permanent magnet is not damaged by centrifugal force. Further, since the permanent magnet fixing member and the rotor core back are integrated, the number of parts and the number of assembly steps do not increase (for example, refer to Patent Document 1).

JP-A-5-76146

  However, the method of using an IPM motor as in Patent Document 1 has the following problems. In order to rotate at high speed, it is necessary to secure the strength of the rotor bridge portion in order to hold the permanent magnet. In other words, in the IPM that supports high-speed rotation, the rotor bridge portion becomes thick, and the permanent magnet is buried deep inside the rotor. This increases the leakage flux of the permanent magnet and decreases the torque. Further, even if the permanent magnet is embedded deep inside the rotor, it is necessary to ensure the same rotor core back in order to ensure motor characteristics. In this case, since the inner diameter of the rotor is reduced, the chuck diameter is reduced when applied to a spindle motor, and the degree of freedom of a tool that can be gripped is reduced.

  Accordingly, an object of the present invention is to provide a rotating electrical machine that can reliably hold a magnet even during high-speed rotation, can obtain a sufficient torque, and can ensure a large rotor inner diameter.

  According to the present invention, a stator having a stator core and a coil wound around the stator core, a rotor body of a low magnetic permeability material rotatably supported with respect to the stator, and a rotor body spaced apart from each other in the rotor body. In a rotating electrical machine including a rotor having a plurality of permanent magnets arranged in a direction, the permanent magnet includes a main magnet having a radial polarity and an auxiliary magnet having a circumferential polarity arranged alternately in the circumferential direction. The rotating electric machine is characterized in that the main magnet and the auxiliary magnet are arranged so that their polarities are opposite to each other in the circumferential direction.

  With this configuration, the permanent magnet can be reliably fixed and the leakage magnetic flux can be reduced, so that sufficient torque can be obtained.

Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view of Embodiment 1 of the rotating electrical machine of the present invention. In FIG. 1, the rotating electrical machine includes a stator 1 and a rotor 2. In the present embodiment, a four-pole / 24-tooth configuration is shown, but any combination of the number of poles and the number of teeth may be used. The stator 1 and the rotor 2 are supported by providing a predetermined gap 3 between them so as to be freely rotatable.

  The stator 1 includes a cylindrical magnetic core stator core 5 provided with a plurality of teeth 4 on an inner peripheral surface, and a coil 6 wound around the teeth 4 of the stator core 5.

  The rotor 2 is rotatably supported with respect to the stator 1 and has a cylindrical rotor body 8 which is a single body having a central hole 7 of a low permeability material such as SUS or CFRP, and a circumferential direction within the rotor body 8. And a plurality of permanent magnets 9 arranged in the circumferential direction of the rotor body 8.

  The permanent magnets 9 are alternately arranged in the circumferential direction and have radial polarities, as indicated by arrows representing the N poles, and the permanent magnets 9 are alternately arranged in the circumferential direction and have circumferential polarity. Auxiliary magnets 11a and 11b are provided, and the main magnets 10a and 10b and the auxiliary magnets 11a and 11b are arranged so that the polarities are alternately reversed in the circumferential direction. That is, in FIG. 1, the arrangement of the permanent magnets 9 in order from the 12 o'clock position in the clockwise direction is the main magnet 10a having the radially outward polarity, the auxiliary magnet 11a having the counterclockwise polarity in the circumferential direction, The main magnet 10b has a polarity in the direction and the auxiliary magnet 11b has a polarity in the clockwise direction in the circumferential direction.

  In the illustrated example, the permanent magnet 9 of the rotor 2 has a plurality of holding holes extending in the axial direction at equal intervals in the circumferential direction in a portion near the surface layer on the side (radial outer periphery) of the rotor body 8 facing the stator 1. 12, a plurality of main magnets 10a and 10b and auxiliary magnets 11a and 11b are inserted into the holding hole 12 one by one and fixed with an adhesive or the like. The main magnets 10a and 10b are magnetized and arranged so as to have different polarities in the radial direction, and the auxiliary magnets 11a and 11b are magnetized and arranged so that magnetic flux flows from both sides in the circumferential direction of the magnet. The hullback arrangement (10a, 11a, 10b, 11b) including the four permanent magnets 9 is repeated twice.

  In other words, the permanent magnet 9 includes main magnets 10a and 10b having radial polarities alternately arranged in the circumferential direction and auxiliary magnets 11a and 11b having circumferential polarities alternately arranged in the circumferential direction. The main magnets 10a and 10b and the auxiliary magnets 11a and 11b are arranged so that their polarities are opposite to each other.

  By the way, in the case of the Halbach arrangement, as described in, for example, Japanese Laid-Open Patent Publication No. 2000-197287, which is a publicly known document, adjacent permanent magnets are generally placed in contact with each other in order to effectively use the generated magnetic flux. However, it was difficult to fix the permanent magnets because the adjacent permanent magnets repelled.

  However, while adopting the Halbach arrangement in this way, the permanent magnet 9 composed of the main magnets 10a and 10b and the auxiliary magnets 11a and 11b is inserted into the holding hole 12 of the rotor body 8 which is a magnet holding member. By embedding and supporting, the permanent magnet 9 can be reliably fixed. Further, contrary to the above-mentioned technical common sense, a gap is formed by the rotor body 8 between the permanent magnets 9 in the hullback arrangement, so that an effect that it is difficult to demagnetize is also obtained. In addition, since the rotor body 8 is made of a low magnetic permeability material, it is difficult for torque to decrease due to leakage magnetic flux even if the rotor body 8 is embedded deep inside to ensure strength. Furthermore, by disposing the permanent magnets 9 in a hullback arrangement, the rotor core back made of a high magnetic permeability material, which has been necessary in the past, becomes unnecessary, and the rotor inner diameter can be increased. Further, the rotor body 8 has a structure in which a plurality of holding holes 12 are formed and the permanent magnet 9 is fixed therein, and the rotor body 8 is an integral part in which the inner part and the outer part of the permanent magnet 9 are continuous. The number of parts does not increase.

Embodiment 2. FIG.
The shape of the permanent magnet 9 is not limited to the columnar body having a fan-shaped cross section shown in FIG. 1, and various other shapes can be used. In the example of the rotor 2 of the rotating electrical machine shown in FIG. It is a rectangular column with a rectangular cross section, and the holding hole 12 has a corresponding quadrangular cross section. Other configurations are the same as those of the rotor 2 of the rotating electrical machine shown in FIG.

  By making the permanent magnet 9 into a quadrangle, the processing cost of the permanent magnet 9 and the holding hole 12 can be reduced, and the manufacture and assembly of the permanent magnet 9 and the rotor body 8 are facilitated.

Embodiment 3 FIG.
The rotor main body 8 of the rotating electrical machine shown in FIG. 3 has a plurality of low-permeability thin plates 13 each coated with an insulating material, whereas the rotor main body 8 shown in FIGS. It is comprised by the laminated body formed by laminating | stacking one sheet.

  When the material of the rotor body 8 is a metal such as SUS or aluminum, an eddy current loss occurs when the rotor body 8 is formed as a single body as in the embodiment of FIG. By configuring as a laminated body, it is possible to reduce eddy current loss generated in the rotor body 8 and to obtain an effect of reducing loss. Further, when the plurality of holding holes 12 are processed in the rotor main body 8 constituted by a single body, the processing cost increases particularly when the rotor diameter is large, but the thin plate 13 of the low permeability material is punched and laminated. As a result, the processing cost can be reduced, and it is possible to flexibly cope with the manufacture of motors having different core widths.

Embodiment 4 FIG.
FIG. 4 is a cross-sectional view of the rotating electrical machine showing the fourth embodiment. Of the permanent magnets 9 (main magnets 10a and 10b and auxiliary magnets 11a and 11b) having a fan-shaped cross section, the auxiliary magnets 11a and 11b magnetized so that magnetic flux flows in the circumferential direction maintained the hullback arrangement of the permanent magnets 9. As it is, it is arranged more radially inward with respect to the main magnets 10a, 10b.

  In the first to third embodiments, the main magnets 10a and 10b magnetized in the radial direction tend to be demagnetized because the magnetic fluxes of the auxiliary magnets 11a and 11b magnetized in the circumferential direction are almost at right angles. By configuring as in Form 4, the angle of the magnetic flux flowing from the auxiliary magnets 11a, 11b to the main magnets 10a, 10b is relaxed, and it is difficult to demagnetize. Further, since the auxiliary magnets 11a and 11b are arranged on the radially inner side, the centrifugal force applied to the auxiliary magnet 11a is reduced, and the strength of the rotor 2 is increased.

Embodiment 5 FIG.
FIG. 5 is a cross-sectional view of the rotating electrical machine showing the fifth embodiment. In this rotating electrical machine, all the permanent magnets 9 (main magnets 10a and 10b and auxiliary magnets 11a and 11b) arranged as shown in FIG. 4 are shown. A rectangular parallelepiped permanent magnet 9 as shown in FIG.

  In the first to third embodiments, the main magnets 10a and 10b magnetized in the radial direction tend to be demagnetized because the magnetic fluxes of the auxiliary magnets 11a and 11b magnetized in the circumferential direction are almost at right angles. By configuring as in the fifth form, the angle of the magnetic flux flowing from the auxiliary magnets 11a and 11b to the main magnets 10a and 10b is relaxed, and it becomes difficult to demagnetize. Further, since the auxiliary magnets 11a and 11b are arranged on the radially inner side, the centrifugal force applied to the auxiliary magnet 11a is reduced, and the strength of the rotor 2 is increased. Furthermore, by making the permanent magnet 9 into a quadrangle, the processing costs of the permanent magnet 9 and the holding hole 12 can be reduced, and the manufacture and assembly of the permanent magnet 9 and the rotor body 8 are facilitated.

Embodiment 6 FIG.
FIG. 6 is a cross-sectional view of the rotating electrical machine showing the sixth embodiment. Among the permanent magnets 9 having a fan-shaped cross section, auxiliary magnets 11a and 11b magnetized so that magnetic flux flows in the circumferential direction are arranged more inside than the main magnets 10a and 10b whose magnetic flux direction is radial. This is the same as the rotating electrical machine shown in FIG. 4, and a high permeability member 14 is arranged inside the main magnets 10a and 10b. The high-permeability member 14 is made of, for example, silicon steel, and has substantially right-angled sides parallel to the inner sides of the main magnets 10a and 10b and the circumferential direction of the auxiliary magnets 11a and 11b, and resembles a right-angled triangle with a curved slope. It is a triangular prism member having a cross-sectional shape, and is arranged so as to smoothly connect adjacent permanent magnets. By configuring in this way, the flow of magnetic flux becomes smoother and torque is improved. The high magnetic permeability member 14 is arranged between the main magnets 10a and 10b and the auxiliary magnets 11a and 11b, so that the flow of magnetic flux can be made smooth. However, the high magnetic permeability member 14 includes the main magnet 10a, The magnetic flux can be flowed more smoothly by being arranged inside the main magnets 10a and 10b so as to face the N pole or S pole of 10b.

Embodiment 7 FIG.
FIG. 7 is a sectional view of a rotating electrical machine showing the seventh embodiment. Among the permanent magnets 9 having a fan-shaped cross section, auxiliary magnets 11a and 11b magnetized so that magnetic flux flows in the circumferential direction are arranged more inside than the main magnets 10a and 10b whose magnetic flux direction is radial. This is the same as the rotating electrical machine shown in FIG. 5, and a high permeability member 14 is arranged inside the main magnets 10a and 10b. The high magnetic permeability member 14 is made of, for example, silicon steel, and has a cross-sectional shape similar to a right triangle whose sides substantially perpendicular to each other are parallel to the inner sides of the main magnets 10a and 10b and the circumferential direction of the auxiliary magnets 11a and 11b, respectively. It is a triangular prism member and is arranged so as to smoothly connect adjacent permanent magnets. By configuring in this way, the flow of magnetic flux becomes smoother and torque is improved. The high magnetic permeability member 14 is arranged between the main magnets 10a and 10b and the auxiliary magnets 11a and 11b, so that the flow of magnetic flux can be made smooth. However, the high magnetic permeability member 14 includes the main magnet 10a, The flow of magnetic flux can be made smoother by being arranged inside 10b.

Embodiment 8 FIG.
FIG. 8 is a cross-sectional view of a rotating electrical machine showing the eighth embodiment. In the present invention, since the permanent magnets 9 composed of the main magnets 10a, 10b whose magnetic flux direction is radial and the auxiliary magnets 11a, 11b whose magnetic flux direction is the circumferential direction are arranged in a hullback arrangement, the rotor core back is Since it becomes unnecessary, a central hole 15 having a large diameter can be provided in the rotor body 8 as shown in FIG. When such a rotating electrical machine is used as a spindle motor for a spindle unit of a machine tool, a large rotor inner diameter can be secured, so that a chuck diameter can be increased, a larger tool can be gripped, and the performance of the spindle unit is improved.

It is sectional drawing of the rotary electric machine in Embodiment 1 of this invention. It is sectional drawing of the rotary electric machine in Embodiment 2 of this invention. It is a perspective view of the rotor main body of the rotary electric machine in Embodiment 3 of this invention. It is sectional drawing of the rotary electric machine in Embodiment 4 of this invention. It is sectional drawing of the rotary electric machine in Embodiment 5 of this invention. It is sectional drawing of the rotary electric machine in Embodiment 6 of this invention. It is sectional drawing of the rotary electric machine in Embodiment 7 of this invention. It is sectional drawing of the rotary electric machine in Embodiment 8 of this invention.

Explanation of symbols

  1 Stator, 2 Rotor, 3 Gap, 4 Teeth, 5 Stator Core, 6 Coil, 7 Center Hole, 8 Rotor Body, 9 Permanent Magnet, 10a, 10b Main Magnet, 11a, 11b Auxiliary Magnet, 12 Holding Hole, 13 Thin Plate, 14 High permeability member, 15 center hole.

Claims (6)

A stator having a stator core and a coil wound around the stator core;
In a rotating electrical machine comprising a rotor body of a low magnetic permeability material rotatably supported with respect to the stator and a rotor having a plurality of permanent magnets arranged in the circumferential direction and spaced apart from each other in the rotor body,
The permanent magnet includes a main magnet having a radial polarity and an auxiliary magnet having a circumferential polarity that are alternately arranged in the circumferential direction, and the main magnet and the auxiliary magnet have opposite polarities in the circumferential direction. The rotating electrical machine is arranged to be.   The rotating electrical machine according to claim 1, wherein the permanent magnet has a rectangular parallelepiped shape.   The rotating electrical machine according to claim 1 or 2, wherein the rotor main body is a laminated body of thin plates of a low magnetic permeability material with an insulating material applied to the surface.   The rotating electrical machine according to any one of claims 1 to 3, wherein the auxiliary magnet is disposed radially inward of the main magnet.   The rotating electrical machine according to any one of claims 1 to 4, wherein a high magnetic permeability member is disposed between the main magnet and the auxiliary magnet.   A spindle unit comprising the rotating electrical machine according to claim 1.

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