JP2012005232A - Polar anisotropic ring magnet and brushless motor having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polar anisotropic ring magnet that reduces manufacturing costs and ensures the accuracy of detecting the position of a rotor.SOLUTION: A ring magnet 40 according to the invention has a plurality of magnetic pole portions 52N and 52S that have polar anisotropy and are arranged in such a manner that N-poles and S-poles are present in an alternating pattern in a circumferential direction of the ring magnet 40. Depressions 50 that open radially outward are formed on an outer circumferential surface of the ring magnet 40, each between a pair of adjacent magnetic pole switching parts 54 in the circumferential direction. Thus, a radial thickness D1 of portions of the ring magnet 40 where the depressions 50 are formed is smaller than a radial thickness D2 of other portions where the depressions 50 are not formed (portions each between the pair of the adjacent depressions 50).

Description

  The present invention relates to a polar anisotropic ring magnet used in a brushless motor and a brushless motor including the same.

  Patent Document 1 discloses a radially oriented ring magnet used for a permanent magnet motor. A plurality of notches are formed on the outer peripheral surface of the ring magnet so as to be positioned between the N pole and the S pole.

Japanese Patent No. 4080376 JP 2004-343907 A

  However, in the example described in Patent Document 1, a radially oriented ring magnet is used, and no consideration is given to a ring magnet having polar anisotropy.

  Also, in a brushless motor equipped with a polar anisotropic ring magnet in the rotor, when detecting the rotational position of the rotor based on the change in magnetic flux accompanying the rotation of the polar anisotropic ring magnet, the position detection accuracy of the rotor is It is desired to be secured.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polar anisotropic ring magnet that can reduce the cost and ensure the position detection accuracy of the rotor. It is in.

  Another object of the present invention is to provide a brushless motor capable of reducing the cost and ensuring the rotational position accuracy of the rotor.

  In order to solve the above problem, the polar anisotropic ring magnet according to claim 1 has a plurality of magnetic poles having polar anisotropy and arranged to alternately repeat N pole and S pole in the circumferential direction. A concave portion that opens radially outwardly between a pair of magnetic pole switching portions that are adjacent to each other on the outer circumferential surface of the outer circumferential surface, and the portion where the concave portion is formed. The thickness in the radial direction is made thinner than the thickness in the radial direction of other portions where the concave portions are not formed.

  According to this polar anisotropic ring magnet, a concave portion that opens radially outward is formed on the outer peripheral surface thereof, whereby a concave portion is formed in the radial thickness of the portion where the concave portion is formed. It is thinner than the radial thickness of other parts that are not. Accordingly, since the magnet material can be reduced by the amount of the recess, the cost can be reduced.

  In addition, since this recess is formed between a pair of magnetic pole switching portions adjacent in the circumferential direction, it is possible to suppress this recess from affecting the change in magnetic flux accompanying the rotation of the polar anisotropic ring magnet. Can do. Thereby, even when the rotational position of the rotor is detected based on the change in magnetic flux accompanying the rotation of the polar anisotropic ring magnet, the position detection accuracy of the rotor can be ensured.

  The polar anisotropic ring magnet according to claim 2 is the polar anisotropic ring magnet according to claim 1, wherein the recess is formed between a pair of magnetic pole switching portions adjacent in the circumferential direction. It is said that.

  According to this polar anisotropic ring magnet, the recesses are respectively formed between a pair of magnetic pole switching portions adjacent in the circumferential direction (since they are formed in the same number as the plurality of magnetic pole portions). It can be reduced more.

  The polar anisotropic ring magnet according to claim 3 is the polar anisotropic ring magnet according to claim 1, wherein the concave portion is one of the N poles and the S poles of the plurality of magnetic pole portions. It is set as the structure each formed in the outer peripheral surface of a part.

  According to this polar anisotropic ring magnet, the concave portion is formed on the outer peripheral surface of each of the magnetic pole portions of either the N pole or the S pole among the plurality of magnetic pole portions. It is possible to reduce the magnet material while facilitating the manufacture.

  The polar anisotropic ring magnet according to claim 4 is the polar anisotropic ring magnet according to any one of claims 1 to 3, wherein the concave portion is in a circumferential direction of the polar anisotropic ring magnet. A pair of outer wall portions adjacent to each other, and the pair of outer wall portions are formed to be curved so as to protrude toward each other and radially outward of the polar anisotropic ring magnet. ing.

  According to this polar anisotropic ring magnet, the pair of outer wall portions constituting the concave portion are formed to be curved so as to protrude toward each other and radially outward of the polar anisotropic ring magnet. Therefore, since the pair of outer wall portions are arranged along the magnetic flux formed in a sine wave shape along the circumferential direction of the polar anisotropic ring magnet, the influence on the magnetic flux can be suppressed.

  Moreover, in order to solve the said subject, the brushless motor of Claim 5 is a rotor which has the polar anisotropy ring magnet as described in any one of Claims 1-4, and the said pole anisotropic. A stator that is arranged on the inner side in the radial direction of the conductive ring magnet, receives a supply of current to form a rotating magnetic field with respect to the polar anisotropic ring magnet, and rotates the rotor; and rotation of the polar anisotropic ring magnet And a control board that controls a current supplied to the stator based on a detection result of the magnetic flux detector.

  According to this brushless motor, since the polar anisotropic ring magnet according to any one of claims 1 to 3 is used for the rotor, the cost is reduced by reducing the cost of the polar anisotropic ring magnet. Can be reduced.

  In addition, since the rotational position of the rotor is controlled based on the change in magnetic flux accompanying the rotation of the polar anisotropic ring magnet, the rotational position accuracy of the rotor can be ensured.

  A brushless motor according to a sixth aspect is the brushless motor according to the fifth aspect, wherein the rotor has a magnet housing member that houses the polar anisotropic ring magnet, and an inner circumferential surface of the magnet housing member The convex portion that is fitted to the concave portion and fixes the polar anisotropic ring magnet is formed.

  According to this brushless motor, the polar anisotropic ring magnet can be firmly fixed to the magnet housing member by fitting the concave portion and the convex portion.

  In addition, since it is not necessary to use an adhesive to fix the ring magnet and the magnet housing member, the cost can be further reduced and the workability at the time of assembling the ring magnet and the magnet housing member is also improved. be able to.

  The brushless motor according to claim 7 is the brushless motor according to claim 6, wherein the magnet housing member is formed in a bottomed cylindrical shape having a bottom portion and a cylindrical portion, and the convex portion is connected to the bottom portion. And it is set as the structure formed in the longitudinal direction along the axial direction on the internal peripheral surface of the said cylindrical part.

  According to this brushless motor, the convex portion is connected to the bottom portion of the magnet housing member and is formed in a longitudinal shape along the axial direction on the inner peripheral surface of the cylindrical portion. Therefore, since this convex part plays the role of a reinforcing rib, the rigidity of the magnet housing member can be improved, and thereby deformation of the magnet housing member can be suppressed.

It is side surface sectional drawing of the brushless motor which concerns on one Embodiment of this invention. It is a disassembled perspective view of the rotor shown by FIG. It is a perspective view which shows the assembly | attachment state of the rotor shown by FIG. It is a top view of the ring magnet shown by FIG. It is a principal part enlarged plan view of the peripheral part of the recessed part shown by FIG. It is a top view which shows the modification of the ring magnet shown by FIG. It is a perspective view which shows the modification of the rotor shown by FIG. It is a perspective view of the fan member shown by FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a brushless motor 10 according to an embodiment of the present invention includes a motor shaft 12, a center piece 14, a stator 16, a rotor 18, and a control board 20 as main components. Yes.

  The center piece 14 includes a flat container-like main body 22 and a cylindrical support 24 that is erected at the center of the main body 22. A bearing 26 is accommodated on the distal end side of the support portion 24, and the motor shaft 12 is rotatably supported by the bearing 26.

  The stator 16 is arranged on the inner side in the radial direction of a ring magnet 40 described later, and includes a stator core 28, a plurality of windings 30, and an insulator 32. The stator core 28 is formed in an annular shape around the motor shaft 12, and is supported by the support portion 24 by fitting the front end side of the support portion 24 inside thereof. Insulators 32 are attached to the stator core 28 from both sides in the axial direction, and windings 30 are wound around the tooth portions 28 </ b> A formed on the stator core 28 via the insulators 32.

  The rotor 18 includes a magnet housing member 38 and a ring magnet 40 (polar anisotropic ring magnet). The magnet housing member 38 is provided coaxially with the stator core 28 and is formed in a bottomed cylindrical shape having a bottom portion 42 and a cylindrical portion 44. A hole portion 46 penetrating in the axial direction is formed in the central portion of the bottom portion 42, and the front end side of the motor shaft 12 is press-fitted into the hole portion 46, so that the magnet housing member 38 is integrated with the motor shaft 12. It is fixed so that it can rotate.

  As shown in FIG. 2, a plurality of convex portions 48 that are connected to the bottom portion 42 and extend in the longitudinal direction along the axial direction of the cylindrical portion 44 are formed on the inner peripheral surface of the cylindrical portion 44. The plurality of convex portions 48 are formed at intervals in the circumferential direction of the cylindrical portion 44.

  On the other hand, on the outer peripheral surface of the ring magnet 40, a plurality of concave portions 50 that are opened outward in the radial direction are formed at intervals in the circumferential direction. The plurality of recesses 50 are formed in the same number as the plurality of protrusions 48 described above. As shown in FIG. 3, the ring magnet 40 is housed inside the magnet housing member 38 and is fixed to the magnet housing member 38 by fitting the convex portion 48 with the concave portion 50. .

  More specifically, the ring magnet 40 has a plurality of magnetic pole portions 52N and 52S arranged so as to alternately repeat N and S poles in the circumferential direction, as shown in FIG. Configured. The plurality of magnetic pole portions 52N and 52S are magnetized so as to have polar anisotropy. The magnetic pole part 52N has an N pole, and the magnetic pole part 52S has an S pole.

  The plurality of recesses 50 described above are formed between the pair of magnetic pole switching portions 54 adjacent to each other in the circumferential direction, and are formed at the center in the circumferential direction on the outer peripheral surfaces of the magnetic pole portions 52N and 52S. In the ring magnet 40, the radial thickness D1 of the portion where the recess 50 is formed is the other portion where the recess 50 is not formed (that is, the portion between a pair of recesses 50 adjacent in the circumferential direction). It is thinner than the radial thickness D2.

  Further, as shown in FIG. 5, the recess 50 is configured to have a pair of outer wall portions 50 </ b> A adjacent to each other in the circumferential direction of the ring magnet 40. The pair of outer wall portions 50A are formed to be curved so as to protrude toward each other and radially outside the ring magnet 40 (that is, the arrow A1 side and the arrow a2 side).

  The control board 20 shown in FIG. 1 is fixed to the center piece 14, and a control IC, a plurality of electric elements, and the like are mounted on the front and back surfaces thereof. Further, a magnetic flux detector 56 configured by, for example, a Hall IC is mounted on the surface of the control board 20 at a position facing the above-described ring magnet 40 in the axial direction.

  In the brushless motor 10, when the rotor 18 is rotated and a change in the magnetic flux accompanying the rotation of the ring magnet 40 is detected by the magnetic flux detector 56, the control board 20 is controlled based on the detection result of the magnetic flux detector 56. The current supplied to the stator 16 is controlled by the control IC. Further, when a current is supplied, a rotating magnetic field is formed from the stator 16 to the ring magnet 40, whereby the rotor 18 is rotated.

  Next, the operation and effect of one embodiment of the present invention will be described.

  According to one embodiment of the present invention, as shown in FIG. 4, the outer peripheral surface of the ring magnet 40 is formed with a recess 50 that opens radially outward, whereby the recess 50 in the ring magnet 40 is formed. The thickness D1 in the radial direction of the part where the concave portion 50 is formed is thinner than the thickness D2 in the radial direction of the other part where the concave portion 50 is not formed. Therefore, since the magnet material can be reduced by the amount of the concave portion 50 formed, the cost of the ring magnet 40 and hence the cost of the brushless motor 10 can be reduced.

  In particular, since the recesses 50 are respectively formed between a pair of magnetic pole switching portions 54 adjacent in the circumferential direction (since they are formed in the same number as the plurality of magnetic pole portions 52N and 52S), the magnet material can be further reduced. And cost can be further reduced.

  Further, since the concave portion 50 is formed between a pair of magnetic pole switching portions 54 adjacent in the circumferential direction, it is possible to suppress the concave portion 50 from affecting the change in magnetic flux accompanying the rotation of the ring magnet 40. it can. Thereby, even when the rotational position of the rotor 18 is detected based on the change of the magnetic flux accompanying the rotation of the ring magnet 40, the position detection accuracy of the rotor 18 can be ensured, and as a result, the rotational position accuracy of the rotor 18 is ensured. be able to.

  Further, as shown in FIG. 5, the pair of outer wall portions 50A constituting the concave portion 50 are on the sides of each other and on the radially outer side of the ring magnet 40 (that is, the arrow A side that is the arrow a1 side and the arrow a2 side). It is curved to form a convex shape. Accordingly, since the pair of outer wall portions 50A are arranged along the magnetic flux M formed in a sine wave shape along the circumferential direction of the ring magnet 40, the influence on the magnetic flux M can be suppressed.

  Further, as shown in FIG. 3, the ring magnet 40 can be firmly fixed to the magnet housing member 38 by fitting the concave portion 50 and the convex portion 48 described above.

  In addition, since it is not necessary to use an adhesive to fix the ring magnet 40 and the magnet housing member 38, the cost can be further reduced and the work when the ring magnet 40 and the magnet housing member 38 are assembled. Can also be improved.

  Further, as shown in FIG. 2, the convex portion 48 is coupled to the bottom portion 42 of the magnet housing member 38 and is formed in a longitudinal shape along the axial direction on the inner peripheral surface of the cylindrical portion 44. Therefore, since this convex part 48 plays the role of a reinforcing rib, the rigidity of the magnet housing member 38 can be improved, and thereby deformation of the magnet housing member 38 can be suppressed.

  Next, a modification of one embodiment of the present invention will be described.

  In the above embodiment, the plurality of recesses 50 are respectively formed between a pair of magnetic pole switching portions 54 adjacent in the circumferential direction (although they are formed in the same number as the plurality of magnetic pole portions 52N and 52S), FIG. As shown in FIG. 5, it may be formed only on the outer peripheral surface of the magnetic pole portion 52N composed of N poles. Further, although not particularly illustrated, the plurality of concave portions 50 may be formed only on the outer peripheral surface of the magnetic pole portion 52S composed of the S pole.

  If comprised in this way, magnet material can be reduced, making manufacture of the ring magnet 40 easy.

  Further, as shown in FIGS. 7 and 8, a plurality of blades 58 are formed on the outer peripheral surface of the magnet housing member 38, and the fan member 60 is configured by the magnet housing member 38 and the plurality of blades 58. May be. That is, the above-described brushless motor 10 (see FIG. 1) may be configured as a fan motor.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and other various modifications can be made without departing from the spirit of the present invention. It is.

DESCRIPTION OF SYMBOLS 10 ... Brushless motor, 12 ... Motor shaft, 14 ... Center piece, 16 ... Stator, 18 ... Rotor, 20 ... Control board, 22 ... Main part, 24 ... Supporting part, 26 ... bearing, 28 ... stator core, 28A ... teeth part, 30 ... winding, 32 ... insulator, 38 ... magnet housing member, 40 ... ring magnet (Polar anisotropic ring magnet), 42 ... bottom, 44 ... cylindrical part, 46 ... hole, 48 ... convex part, 50 ... concave part, 50A ... outer wall part, 52N, 52S ... magnetic pole part, 54 ... magnetic pole switching part, 56 ... magnetic flux detector, 58 ... blade, 60 ... fan member

Claims (7)

  A pair of magnetic pole portions having polar anisotropy and arranged so as to alternately repeat the N pole and the S pole in the circumferential direction, and a pair of adjacent outer circumferential surfaces in the circumferential direction. A recess opening radially outward is formed between the magnetic pole switching portions, and the radial thickness of the portion where the recess is formed is larger than the radial thickness of the other portion where the recess is not formed. Thinly formed polar anisotropic ring magnet. The recesses are respectively formed between a pair of magnetic pole switching portions adjacent in the circumferential direction.
The polar anisotropic ring magnet according to claim 1. The recesses are respectively formed on the outer peripheral surface of each of the magnetic pole portions of either the N pole or the S pole among the plurality of magnetic pole portions.
The polar anisotropic ring magnet according to claim 1. The recess has a pair of outer wall portions adjacent to each other in the circumferential direction of the polar anisotropic ring magnet,
The pair of outer wall portions are formed to be curved so as to protrude toward each other and radially outward of the polar anisotropic ring magnet.
The polar anisotropic ring magnet according to any one of claims 1 to 3. A rotor having the polar anisotropic ring magnet according to any one of claims 1 to 4,
A stator that is disposed radially inward of the polar anisotropic ring magnet, receives a supply of current to form a rotating magnetic field with respect to the polar anisotropic ring magnet, and rotates the rotor;
A control board for detecting a change in magnetic flux accompanying rotation of the polar anisotropic ring magnet, and for controlling a current supplied to the stator based on a detection result of the magnetic flux detector;
Brushless motor with The rotor has a magnet housing member that houses the polar anisotropic ring magnet,
On the inner peripheral surface of the magnet housing member, a convex portion that is fitted to the concave portion and fixes the polar anisotropic ring magnet is formed.
The brushless motor according to claim 5. The magnet housing member is formed in a bottomed cylindrical shape having a bottom portion and a cylindrical portion,
The convex portion is connected to the bottom portion, and is formed in a longitudinal shape along the axial direction on the inner peripheral surface of the cylindrical portion.
The brushless motor according to claim 6.

Images