JP6530530B2 - Brushless motor - Google Patents

Description

  The present invention relates to a rotor and a brushless motor.

  Conventionally, a motor is used as a drive source of various devices and products. For example, it is employed in applications of power sources including office equipment such as printers and copiers, various home appliances, and vehicle assists such as automobiles and electric bicycles. In particular, a brushless motor may be used from the viewpoint of durability and electrical noise as a drive source for moving parts that frequently operate.

  As a type of brushless motor, an interior permanent magnet in which a permanent magnet is embedded in a rotor is known. Also, a motor is devised in which an adhesive is used to fix the permanent magnet in the hole of the rotor core (see, for example, Patent Document 1).

JP, 2005-269804, A

  However, in the above-described motor, a plurality of plates are used in addition to the adhesive in order to prevent fixation and detachment of the permanent magnet in the rotor core, and the number of parts is large and the manufacturing process is complicated.

  The present invention has been made in view of these circumstances, and an object thereof is to provide a simple and reliable technique for fixing a magnet in a rotor.

  In order to solve the above-mentioned subject, a rotor of an embodiment of the present invention is provided with a rotor core, a plurality of magnets, and an adhesive which fixes the magnets to the rotor core. The rotor core includes an annular portion around a hole into which the rotation shaft is inserted, a plurality of pole pieces radially formed from the annular portion, and a plurality of magnet accommodating portions radially disposed between adjacent pole pieces. And. The magnet is accommodated in the magnet accommodating portion such that the same magnetic poles as other adjacent magnets face each other in the circumferential direction of the rotor core. The adhesive adheres between the magnet and the two circumferential inner surfaces of the magnet housing portion to the magnet, and the first adhesive portion reaching one axial end of the magnet and one of the axial directions of the rotor core On the end face side, the end face of the rotor core and the end face in the axial direction of the magnet are adhered, and the second adhesion part connected to the first adhesion part is provided.

  According to this aspect, the two circumferential surfaces of the magnet are bonded and fixed to the inner surface of the magnet housing by the first bonding portion, and the axial movement of the magnet is further restricted by the second bonding portion. Therefore, the magnet can be firmly fixed at a predetermined position of the magnet housing without using any member other than the adhesive.

  The pole piece may be separated from the adjacent other pole piece and the outer periphery. In this case, since only the end on the central axis side of each pole piece is connected to the annular portion, the pole pieces are easily displaced. However, according to this aspect, since the pole piece and the pole piece adjacent to the pole piece are integrally fixed by the adhesive via the magnet, the displacement of each pole piece is suppressed and the rigidity of the rotor itself is reduced. It can improve.

  The magnet may have a magnetic force of 8 MGOe or more on the main surface. When such magnets are housed in the magnet housing portion such that the same magnetic poles as other adjacent magnets face each other in the circumferential direction of the rotor core, they tend to move in the axial direction of the rotor due to a large repulsive force. However, since the movement can be restricted by the second bonding portion, the magnet is fixed more firmly than in the case where only the first bonding portion is provided.

  Another aspect of the present invention is a brushless motor. The brushless motor has a rotor, a stator having a central portion with a space in which the rotor is disposed, an accommodating member for accommodating the rotor and the stator, and a rotational position of the rotor based on fluctuations of a magnetic field accompanying the rotation of the rotor. And a detection unit that detects the detected signal. The detection portion is disposed at a position opposite to the other end surface opposite to the one end surface of the rotor core where the second bonding portion is present.

  According to this aspect, since there is no second adhesion part between the end face in the axial direction of the magnet and the detection part, the second adhesion part interferes with the detection part or the second adhesion part affects the detection accuracy of the detection part Can be prevented.

  The first adhesive portion may have a coating range of 0.5 to 0.9 L in the axial direction, where L is the total length of the magnet in the axial direction. As a result, the adhesive is suppressed from protruding from the other end face of the magnet, and the adhesive can be prevented from interfering with the detection portion or affecting the detection accuracy.

  Another aspect of the invention is a rotor. The rotor comprises a rotor core, a plurality of magnets, and an adhesive for securing the magnets to the rotor core. The rotor core includes an annular portion around a hole into which the rotation shaft is inserted, a plurality of pole pieces radially formed from the annular portion, and a plurality of magnet accommodating portions radially disposed between adjacent pole pieces. And. The pole piece is separated from the adjacent other pole piece and the outer peripheral portion, and the magnet is accommodated in the magnet housing portion such that the same magnetic poles as the adjacent other magnet face each other in the circumferential direction of the rotor core, The adhesive has a bonding portion bonding between the two circumferential inner surfaces of the magnet housing and the magnet.

  According to this aspect, the magnets and the pole pieces alternately arranged in the circumferential direction of the rotor are adhered and fixed to each other over the entire circumference. Therefore, the rigidity of the entire rotor can be improved even in the rotor core in which the outer peripheral portions of the pole pieces are separated and the strength is insufficient.

  It is to be noted that arbitrary combinations of the above-described components, and those obtained by converting the expression of the present invention among parts, manufacturing methods, systems, etc. are also effective as aspects of the present invention.

  According to the present invention, it is possible to realize a simple and reliable rotor for fixing a magnet.

FIG. 1 is an overall perspective view of a brushless motor according to an embodiment of the present invention. It is a side view of the brushless motor concerning this embodiment. FIG. 2 is an exploded perspective view of the brushless motor according to the present embodiment. It is a side sectional view of a brushless motor concerning this embodiment. FIG. 5 (a) is a top view of a rotor core according to the present embodiment, and FIG. 5 (b) is a top view showing a state in which a magnet is fitted to the rotor core shown in FIG. 5 (a). FIG. 5 is a top view of a portion of the rotor as viewed in the direction of arrow X shown in FIG. 4; It is the figure which looked at the AA cross section of the rotor shown in FIG. It is BB sectional drawing of a rotor shown in FIG. It is a schematic diagram for demonstrating a part of process of the manufacturing method of the rotor which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, and overlapping descriptions will be omitted as appropriate. Further, the configurations described below are exemplifications and do not limit the scope of the present invention. Hereinafter, an inner rotor type brushless motor will be described as an example.

(Brushless motor)
FIG. 1 is an overall perspective view of a brushless motor according to the present embodiment. FIG. 2 is a side view of the brushless motor according to the present embodiment. FIG. 3 is an exploded perspective view of the brushless motor according to the present embodiment. FIG. 4 is a side sectional view of the brushless motor according to the present embodiment.

  A brushless motor (hereinafter sometimes referred to as "motor") 10 according to the present embodiment includes a columnar rotor 12 having a magnet, and a stator 14 having a space in which the rotor 12 is disposed at a central portion thereof. A front bell 16, a housing main body 18, and a power feeding unit 19 are provided.

  The front bell 16 is a plate-like member, and a hole 16a is formed in the center so that the rotary shaft 20 can penetrate, and a recess 16b for holding the bearing 22 is formed in the vicinity of the hole 16a. The front bell 16 supports a part of the rotary shaft 20 of the rotor 12 via the bearing 22. The housing body 18 is a cylindrical member, and a hole 18b is formed at the center of the base 18a, and a recess 18c for holding the bearing 24 is formed in the vicinity of the hole 18b. The housing body 18 supports the other portion of the rotary shaft 20 of the rotor 12 via the bearing 24. In the present embodiment, the front bell 16 and the housing body 18 constitute a housing member for housing the rotor 12 and the stator 14.

  The detection unit 30 shown in FIG. 4 detects a signal corresponding to the rotational position of the rotor 12 based on the variation of the magnetic field accompanying the rotation of the rotor 12. Specifically, the detection element 32 such as a Hall element, a Hall IC, and a MR (Magnetic Resistance) element is mounted on the substrate 34. The detection unit 30 according to the present embodiment includes three detection elements 32.

  The front bell 16 is formed in the center of the base portion 16c and the base portion 16c, and is integrally formed around the support portion 16d supporting the rotary shaft 20 via the bearing 22 and the support portion 16d, and the detection portion 30 is attached And a placement unit 16e. As shown in FIG. 4, the mounting portion 16 e protrudes from the base portion 16 c toward the end surface 12 a of the rotor 12 and protrudes to a position not interfering with the stator winding 43.

(Rotor)
FIG. 5 (a) is a top view of a rotor core according to the present embodiment, and FIG. 5 (b) is a top view showing a state in which a magnet is fitted to the rotor core shown in FIG. 5 (a).

  The rotor 12 includes a circular rotor core 26 and a plurality of magnets 28. At the center of the rotor core 26, a through hole 26a is formed which is fixed in a state in which the rotating shaft 20 is inserted. The rotor core 26 has an annular portion 26c around the through hole 26a into which the rotary shaft 20 is inserted, a plurality of fan-shaped magnetic pole pieces 26d formed radially from the annular portion 26c, and the magnets 28 inserted and fixed. And a plurality of magnet housing portions 26b. The magnet 28 is a plate-like member corresponding to the shape of the magnet housing portion 26 b. Further, the magnet housing portion 26b is radially disposed between two adjacent pole pieces 26d.

  And each of these members is assembled in order. Specifically, each of the plurality of (14) magnets 28 is fitted into the corresponding magnet housing portion 26 b using an adhesive described later, and the rotary shaft 20 is inserted into the through hole 26 a of the rotor core 26. The bearing 22 and the bearing 24 are attached to the rotating shaft 20.

(Rotor core)
The rotor core 26 shown in FIG. 5A is obtained by laminating a plurality of plate-like members. Each of the plurality of plate-like members is manufactured by punching out a non-oriented electromagnetic steel sheet (for example, silicon steel sheet) in a predetermined shape as shown in FIG. 5A by press processing. The magnet housing portions 26 b are radially disposed around the rotation axis of the rotor core 26. In addition to the above, the rotor core 26 can also be formed into an arbitrary shape using a powder magnetic material.

  As shown in FIG. 5B, the magnets 28 are housed in the magnet housing portion 26b such that the same magnetic poles as the adjacent magnets face each other in the circumferential direction of the rotor core 26. That is, the magnet 28 is configured such that two main surfaces 28a and 28b having a large surface area out of six surfaces of a substantially rectangular parallelepiped form an N pole and an S pole, respectively. As a result, magnetic lines of force emerging from the main surface 28 a of the magnet 28 are directed out of the rotor core 26 from the area between the two magnets 28. As a result, the rotor 12 according to the present embodiment functions as a magnet having a total of 14 poles of seven N poles and seven S poles alternately on its outer peripheral portion.

  The magnet 28 is, for example, a bonded magnet or a sintered magnet. The bonded magnet is a magnet obtained by kneading a magnetic material into rubber, resin or the like and injection molding or compression molding. On the other hand, a sintered magnet is a magnet obtained by burning a powdered magnetic material at a high temperature, and it is easier to improve the residual magnetic flux density than a bonded magnet.

(Fixing structure of magnet)
As in the rotor 12 according to the present embodiment, when the magnet 28 is housed in the magnet housing portion 26 b so that the same magnetic poles as the other adjacent magnets 28 face each other in the circumferential direction of the rotor core 26, the rotor 12 A repulsive force is generated to move away from each other in the direction of the rotation axis. In particular, when the magnetic force of the magnet 28 is high, the repulsive force is also increased, and thus, it is necessary to further fix the magnet 28.

  The rotor 12 according to the present embodiment realizes a fixing structure with an adhesive in consideration of this point. 6 is a top view of a portion of rotor 12 as viewed in the direction of arrow X shown in FIG. 7 is a view of a cross section AA of the rotor 12 shown in FIG. FIG. 8 is a cross-sectional view of the rotor 12 shown in FIG.

  As shown in FIGS. 6-8, the rotor 12 includes an adhesive 50 that secures the plurality of magnets 28 to the rotor core 26. The adhesive 50 adheres between the two inner surfaces 26 e in the circumferential direction of the magnet housing portion 26 b and the magnet 28, and reaches the first end surface 28 c (see FIG. 7) of the magnet 28 in the axial direction Ax. It has the adhesion part 50a. The adhesive 50 also has a second bonding portion 50 b that bonds the end face 26 f of the rotor core 26 and one end face 28 c of the magnet 28 in the axial direction Ax on the side of the end face 26 f in the axial direction Ax of the rotor core 26. Moreover, the 1st adhesion part 50a is connected with the 2nd adhesion part 50b.

  In the rotor 12 having such a configuration, the two principal surfaces 28a and 28b in the circumferential direction of the magnet 28 are bonded to the magnet housing portion 26b by the first bonding portion 50a, and the shaft of the magnet 28 is formed by the second bonding portion 50b. Directional movement is further restricted. Therefore, the magnet 28 can be firmly fixed at a predetermined position of the magnet housing portion 26b without using any other member than the adhesive.

  As the adhesive 50, various types of adhesives such as acrylic and epoxy can be applied, but preferably, an acrylic material may be included. This enables adhesion at a relatively low temperature, and, for example, can reduce the influence of the demagnetization of the magnet due to the heat treatment of the adhesive.

  In the pole piece 26d according to the present embodiment, the outer peripheral portion is separated from the adjacent other pole piece 26d (see FIG. 5A). In this case, since each pole piece 26d is fixed as a rotor core only by connection of the central axis side end to the annular portion 26c, the pole piece 26d is easily displaced. However, in the rotor 12 according to the present embodiment, since the pole piece 26 d adjacent to the pole piece 26 d is integrally fixed by the adhesive 50 via the magnet 28, the displacement of each pole piece 26 d is Be suppressed.

  Further, by mutually bonding the magnets 28 and the pole pieces 26d alternately arranged in the circumferential direction of the rotor over the entire circumference, the rigidity of the entire rotor 12 can be improved, and the vibration and noise of the motor can be reduced. At the same time, quality improvement and performance stabilization of the motor can be realized.

  Moreover, although the fixing method of the magnet in the rotor according to the present embodiment is applicable regardless of the magnetic force of the magnet 28, for example, the effect is remarkable when the magnetic force of the main surface is 8 MGOe or more. . As described above, when the magnets 28 having a large magnetic force are accommodated in the magnet accommodating portion 26b, they are separated from each other by a large repulsive force. The movement of the magnet 28 is mechanically fixed in the radial and circumferential directions by the shape of the rotor core 26, and as a result, it tends to move in the axial direction of the rotor. However, since the movement can be restricted by the second bonding unit 50b according to the present embodiment, the magnet 28 is firmly fixed as compared with the case where only the first bonding unit 50a is provided.

  Specifically, when a force is applied to the magnet 28 in the direction of the arrow X1 shown in FIG. 7, one end face 26f of the rotor core 26 and one end face 28c of the magnet 28 are mutually connected via the second bonding portion 50b. And restricts the movement of the magnet 28 relative to the rotor core 26. On the other hand, when a force is applied to the magnet 28 in the direction of the arrow X2 shown in FIG. 7, the second adhesive portion 50b serves as a locking portion to restrict the magnet 28 from moving relative to the rotor core 26. ing. Thus, the adhesive 50 prevents the magnet 28 from moving in the axial direction Ax also by the second bonding portion 50 b in addition to the first bonding portion 50 a.

  In particular, the second adhesive portion 50b is integrally connected to the first adhesive portion 50a, so that the movement of the magnet 28 in the axial direction Ax is particularly strongly restricted when the adhesive is cured. Is possible.

  Further, in the motor 10 according to the present embodiment, the detection unit 30 is disposed at a position opposite to the other end surface 26g opposite to the one end surface 26f of the rotor core 26 where the second bonding unit 50b exists. There is. By arranging the detection unit 30 in this manner, the second adhesion unit 50 b and the detection unit 30 do not have the second adhesion unit 50 b between the other end surface 28 d in the axial direction Ax of the magnet 28 and the detection unit 30. Interference or the influence of the second bonding unit 50b on the detection accuracy of the detection unit 30 can be prevented.

  Further, assuming that the entire length in the axial direction of the magnet of the first adhesive portion 50a is L, the coating range R in the axial direction is preferably 0.5 L or more. Thereby, a desired fixing force can be obtained in the adhesive force by the first adhesive portion 50a. On the other hand, if the application range R is 0.9 L or less, the first adhesive portion 50a is the adhesive 50 from the other end face 28d of the detection portion 30 side of the magnet 28 due to the dispersion at the time of manufacture or the adhesive exudation. Overflow is suppressed, and the adhesive 50 can be prevented from interfering with the detection unit 30 or affecting the detection accuracy.

  In addition, since the first bonding portion 50a is on both of the main surfaces 28a and 28b of the magnet 28, it is possible to prevent the magnet 28 from being displaced in the circumferential direction of the rotor inside the magnet housing portion 26b. As a result, generation of vibration and noise of the motor can be reduced.

  In the present embodiment, the configuration has been described in which the magnets 28 are arranged in an I-shape as the plurality of magnets 28 arranged radially, but the same may be applied to a configuration in which the magnets 28 are arranged in a V-shape etc. Can be said.

(How to attach the magnet)
FIG. 9 is a schematic view for illustrating a part of the process of the method of manufacturing a rotor according to the present embodiment. In the process shown in FIG. 9, the magnet 28 is fixed to the magnet housing portion 26 b of the rotor core 26 using the adhesive 50. First, a predetermined amount of adhesive 50 is potted at predetermined positions on the two inner surfaces 26e of the magnet housing portion 26b. Here, the predetermined position is an end of the desired application range R. Next, the magnet 28 is inserted from the side opposite to the application range R, and while applying the adhesive 50 at one end face 28 c of the magnet 28, the one end face 28 c is pushed to a position substantially coincident with the end face 26 f of the rotor core 26 . Thereby, the above-mentioned 1st adhesion part 50a and the 2nd adhesion part 50b are formed.

  The specifications of the brushless motor which can suitably use the present invention will be described below. The brushless motor according to the present embodiment has an outer diameter of about 30 to 140 mm, preferably about 35 to 80 mm. Further, the number of grooves (teeth) of the stator is 12, for example. The number of magnets is preferably 10 or 14. Further, the magnetic force (energy product) of the magnet is 8 MGOe or more, preferably 10 MGOe or more, and more preferably 30 MGOe or more. Moreover, as for the diameter of a rotor, about 20-70 mm is preferable.

  As mentioned above, although the present invention was explained with reference to the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment, but it is not limited to the above-mentioned embodiment. It is included in the present invention. In addition, it is also possible to appropriately change the combination and order of processing in each embodiment based on the knowledge of those skilled in the art and to add various modifications such as design changes to the embodiment, and such modifications Additional embodiments may be included within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 motor, 12 rotors, 12a end face, 18 housing main body, 20 rotary shaft, 26 rotor core, 26a through hole, 26b magnet accommodation part, 26c annular part, 26d pole piece, 26e inner surface, 26f, 26g end face, 28 magnet, 28a main Face, 28c, 28d End face, 30 detection part, 50 adhesive, 50a 1st bonded part, 50b 2nd bonded part.

Claims (7)

With the rotor,
A stator having a central portion with a space in which the rotor is disposed;
A housing member for housing the rotor and the stator;
And a detection unit that detects a signal corresponding to the rotational position of the rotor based on the variation of the magnetic field accompanying the rotation of the rotor.
The rotor is
A rotor core,
With multiple magnets,
An adhesive for fixing the magnet to the rotor core;
The rotor core is
Has multiple magnet housings,
The magnet is housed in the magnet housing portion,
The adhesive is
A first bonding portion which adheres between an inner surface of the magnet housing portion and the magnet and reaches one axial end of the magnet;
On one end face side in the axial direction of the rotor core, the end face of the rotor core is bonded to the end face in the axial direction of the magnet, and a second bonding portion connected to the first bonding portion is provided.
Wherein the detection unit includes said second one end face of the rotor core bonding portion is present is disposed on the other end face opposite to the position on the opposite side,
The first adhesive portion does not reach the other axial end of the magnet.
A brushless motor characterized by The rotor core is
An annular portion around a hole into which the rotation shaft is inserted;
A plurality of pole pieces radially formed from the annular portion;
The brushless motor according to claim 1, comprising:   The brushless motor according to claim 2, wherein the plurality of magnet housings are radially disposed between the adjacent pole pieces.   4. The brushless motor according to claim 3, wherein the magnet is housed in the magnet housing portion such that the same magnetic poles as other adjacent magnets face each other in the circumferential direction of the rotor core.   The brushless motor according to any one of claims 1 to 4, wherein the magnet is exposed at the other end in the axial direction of the magnet.   The magnet according to any one of claims 1 to 5, wherein the end face of the rotor core and the end face of the magnet in the axial direction are not bonded at the first bonding portion on the other end face side of the rotor core in the axial direction. The brushless motor according to any one of the above.   The application range in the axial direction is 0.5 to 0.9 L, where L is the total length in the axial direction of the magnet, in the first adhesive portion, any one of claims 1 to 6 characterized in that Brushless motor described.

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