JP7006103B2 - Rotor and motor - Google Patents

Description

The present invention relates to a rotor and a motor.

Conventionally, a so-called IPM type rotor in which a permanent magnet is embedded in a rotor core is known. In the IPM type rotor, a structure for obtaining reluctance torque is considered. For example, in the rotor of Patent Document 1, the permanent magnet in the rotor core is formed by forming the shape of the permanent magnet into an arc shape that curves inward in the radial direction. The volume of the part located on the outer peripheral side of the magnet is secured to improve the reluctance torque.

Japanese Unexamined Patent Publication No. 2013-143791

In recent years, motors have been miniaturized, but in small motors, how to secure magnet torque has become an issue. However, in a configuration in which the permanent magnet is simply arcuate as in the rotor of Patent Document 1, although the reluctance torque can be secured, the volume of the permanent magnet becomes small, and there is room for improvement in improving the magnet torque. was there.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotor and a motor capable of suitably securing both reluctance torque and magnet torque.

The rotors that solve the above problems include a rotating shaft, a substantially cylindrical rotor core that is integrally rotatably fixed to the rotating shaft, and a plurality of permanent rotors that are embedded inside the rotor core at intervals in the circumferential direction. A rotor provided with a magnet, wherein the permanent magnet is paired in the circumferential direction with a first radial side surface on the outer peripheral side and a second radial side surface on the inner peripheral side, which are paired in the radial direction. And a pair of circumferential side surfaces connecting the circumferential ends of the second radial side surface, the circumferential side surface having a magnetic pole boundary between the permanent magnets adjacent to each other in the axial direction in the axial direction. It forms a straight line parallel to the virtual line connecting the rotation axis, and the first radial side surface is located on the inner peripheral side of the virtual circle that passes through the outer peripheral side end of the circumferential side surface with the rotation axis as the center. It is formed so that the thickness between the circumferential side surface and the constituent surface in the direction orthogonal to the circumferential side surface becomes thicker toward the inner side in the radial direction , and follows the virtual line. The length of the circumferential side surface in the direction is set longer than the radial length from the circumferential center of the first radial side surface to the outer peripheral surface of the rotor core, and the permanent magnet is adjacent to the permanent magnet of the S pole. It has a polar polar orientation that curves so that the inside in the radial direction becomes convex toward the permanent magnet of the N pole, and has a magnetization orientation that intersects the circumferential side surface .

According to this configuration, the first radial side surface of the permanent magnet has a configuration surface located on the inner peripheral side of the virtual circle passing through the outer peripheral side end of the circumferential side surface about the rotation axis, and thus is permanent in the rotor core. The volume of the portion located on the outer peripheral side of the magnet can be secured, and as a result, the reluctance torque can be secured. Further, according to this configuration, the thickness between the circumferential side surface and the constituent surface in the direction orthogonal to the circumferential side surface is formed so as to become thicker toward the inner side in the radial direction. Therefore, it is possible to increase the volume ratio of the permanent magnet as compared with the case of using the conventional arc-shaped permanent magnet, and as a result, the magnet torque can be improved. Further, since the volume of the permanent magnet is increased in the vicinity of the circumferential end of the permanent magnet, it is possible to effectively suppress the demagnetization of the permanent magnet by an external magnetic field in the vicinity of the circumferential end, and as a result, the magnet torque. Can be effectively improved.

According to this configuration, the thickness between the circumferential side surface and the constituent surface of the first radial side surface of the permanent magnet can be increased. Therefore, it is possible to more effectively suppress the demagnetization of the permanent magnet by the external magnetic field in the vicinity of the peripheral end portion, and as a result, the magnet torque can be further improved.

According to this configuration, since the magnetic orientation of the permanent magnet intersects the circumferential side surface, in this configuration, it is easy to secure the thickness between the circumferential side surface and the constituent surface of the permanent magnet. It is possible to construct a long magnetic path that intersects with. As a result, the permeance between the circumferential side surface and the constituent surface of the permanent magnet is improved, and the demagnetization resistance in the portion is improved.
In the rotor, the constituent surface has a shape of being recessed inward in the radial direction in the axial direction.
According to this configuration, the radial thickness of the portion of the rotor core located on the outer peripheral side of the permanent magnet can be suitably secured, and as a result, the reluctance torque can be effectively improved.

A motor that solves the above problems includes the rotor described above.
According to this configuration, it is possible to provide a motor capable of suitably securing both reluctance torque and magnet torque.

According to the rotor and the motor of the present invention, it is possible to suitably secure both the reluctance torque and the magnet torque.

It is sectional drawing of the motor of an embodiment. It is a top view which shows the rotor of the same form partially. It is a top view which shows the rotor of a modification partially.

Hereinafter, an embodiment of the rotor and the motor will be described.
The motor 10 of the present embodiment shown in FIG. 1 is a brushless motor. The motor 10 includes an annular stator 12 fixed to the inner peripheral surface of the motor housing 11 and a rotor 14 arranged radially inside the stator 12 and having a rotating shaft 13.

The stator 12 has a cylindrical stator core 15, and the outer peripheral surface of the stator core 15 is fixed to the motor housing 11. A plurality of (12 in this embodiment) teeth 16 formed along the axial direction and arranged at equal pitches in the circumferential direction are formed on the inside of the stator core 15 so as to extend inward in the radial direction. ing. Each tooth 16 is a T-shaped tooth, and its radial inner peripheral surface 16a is an arc surface extending in the axial direction from a concentric arc centered on the axis of the rotating shaft 13 (rotating axis L1). be. A three-phase winding 17 is wound around each tooth 16 by a centralized winding. Then, a three-phase power supply voltage is applied to the windings 17 of each phase to form a rotating magnetic field in the stator 12, and the rotor 14 fixed to the rotation shaft 13 arranged inside the stator 12 is rotated. There is.

The rotor 14 arranged inside the stator 12 includes a cylindrical rotor core 21 integrally rotatably fixed to the rotation shaft 13, and a plurality of (8 in this embodiment) permanent rotors embedded inside the rotor core 21. It is configured as an embedded magnet type (IPM type) rotor provided with a magnet 22. The rotor core 21 is configured by laminating a plurality of electrical steel sheets in the axial direction. Further, the rotary shaft 13 is rotatably supported by the motor housing 11 via a bearing (not shown).

The plurality of permanent magnets 22 each constitute a plurality of magnetic pole portions 14p of the rotor 14 having different poles alternately in the circumferential direction. That is, the rotor 14 of this embodiment is composed of eight poles. Further, the rotor 14 is a full magnet type rotor in which all the magnetic pole portions 14p thereof are composed of a permanent magnet 22. The permanent magnets 22 have the same shape (same size) as each other, and are arranged at equal intervals (45 ° intervals in this embodiment) in the circumferential direction. It is preferable that the permanent magnet 22 is filled in the magnet accommodating hole 21a formed through the rotor core 21 along the axial direction with almost no gap.

Next, the shape of the permanent magnet 22 will be described.
As shown in FIG. 2, the permanent magnet 22 has a slightly curved shape so as to be convex inward in the radial direction in the axial direction. Further, the permanent magnet 22 is formed so as to be axisymmetric with respect to its circumferential center line L2 (a straight line orthogonal to the rotation axis L1 and passing through the circumferential center of the permanent magnet 22).

More specifically, the permanent magnet 22 has first and second radial side surfaces 31 and 32 paired in the radial direction and peripheral side surfaces 33 paired in the circumferential direction. In the pair of radial side surfaces, the outer peripheral side surface is the first radial side surface 31, and the inner peripheral side surface is the second radial side surface 32.

Each circumferential side surface 33 has a linear shape parallel to the virtual line Lv connecting the magnetic pole boundary portion Pb between the permanent magnets 22 adjacent to each other in the circumferential direction and the rotation axis L1 in the axial direction. The first radial side surface 31 is a surface connecting the outer peripheral side ends of each circumferential side surface 33, and the second radial side surface 32 is a surface connecting the inner peripheral side ends of each circumferential side surface 33. .. In other words, each circumferential side surface 33 is a surface connecting the circumferential ends of the first and second radial side surfaces 31, 32. The circumferential side surface 33 is parallel to the circumferential side surface 33 of the permanent magnets 22 adjacent to each other in the circumferential direction.

The first radial side surface 31 has a first constituent surface 31a located at an intermediate portion in the circumferential direction thereof, and a second constituent surface 31b located on both sides of the first constituent surface 31a in the circumferential direction. The first constituent surface 31a has an arc shape that is recessed inward in the radial direction in the axial direction. Further, the first constituent surface 31a is formed so as to be entirely located on the inner peripheral side of the virtual circle Cv passing through the outer peripheral side end portion of each circumferential direction side surface 33 with the rotation axis L1 as the center.

The second constituent surface 31b is located on the virtual circle Cv and is a surface connecting the peripheral end portion of the first constituent surface 31a and the outer peripheral side end portion of the circumferential side surface 33. Further, the second radial side surface 32 has a concentric arc shape with respect to the first constituent surface 31a, and is a curved surface that is recessed inward in the axial direction in the axial direction.

The permanent magnet 22 is formed so that the thickness T between the circumferential side surface 33 and the first constituent surface 31a in the direction orthogonal to the circumferential side surface 33 becomes thicker toward the inner side in the radial direction. .. Further, the length D1 of the circumferential side surface 33 in the direction along the virtual line Lv is set longer than the radial length D2 from the circumferential center 31c of the first radial side surface 31 to the outer peripheral surface of the rotor core 21. .. The distance between the first constituent surface 31a in the radial direction and the outer peripheral surface of the rotor core 21 (that is, the radial thickness of the magnet outer core portion 21b located on the outer peripheral side of the first constituent surface 31a in the rotor core 21) is , It is the longest at the center 31c in the circumferential direction. Further, in the present embodiment, the circumferential center 31c of the first constituent surface 31a coincides with the circumferential center line L2 of the permanent magnet 22.

In FIG. 2, the magnetization orientation of the permanent magnet 22 is indicated by an arrow. The magnetization orientation of the permanent magnet 22 is set to be curved so as to be convex in the radial direction from the permanent magnet 22 of the S pole toward the permanent magnet 22 of the adjacent N pole (extremely opposite orientation). .. That is, the magnetization orientation of the permanent magnet 22 is inclined toward the circumferential center line L2 side of the permanent magnet 22 toward the radial outer side (stator 12 side). Further, the magnetization orientation of the permanent magnet 22 of the present embodiment is set so as to intersect (substantially orthogonal to) the side surface 33 in the circumferential direction and to be orthogonal to the virtual line Lv.

Each permanent magnet 22 is made of, for example, a bonded magnet (plastic magnet, rubber magnet, etc.) or a sintered magnet obtained by mixing magnet powder with a resin and molding and solidifying the magnet powder. The bonded magnet has a higher degree of freedom in shape than the sintered magnet, and can be formed with high dimensional accuracy. When the permanent magnet 22 is used as a bond magnet, it is preferably composed of a rare earth magnet such as a samarium iron nitrogen (SmFeN) magnet, a samarium cobalt (SmCo) magnet, and a neodymium magnet. When the permanent magnet 22 is a sintered magnet, it is preferably composed of a ferrite magnet, a sumalium cobalt (SmCo) magnet, a neodymium magnet, or other rare earth magnet.

Next, the operation of this embodiment will be described.
When a three-phase power supply voltage is applied to the winding 17 of the stator 12 to form a rotating magnetic field, the rotor 14 rotates based on the rotating magnetic field. Specifically, the rotor 14 is rotated by a magnet torque generated by the action of the rotating magnetic field and the magnetic field of each permanent magnet 22, and a relaxation torque generated by the action of the rotating magnetic field on the rotor core 21. ..

Next, the effect of this embodiment will be described.
(1) The first radial side surface 31 of the permanent magnet 22 has a first constituent surface 31a located on the inner peripheral side of the virtual circle Cv passing through the outer peripheral side end of the circumferential side surface 33 with the rotation axis L1 as the center. .. As a result, the volume of the magnet outer core portion 21b located on the outer peripheral side of the permanent magnet 22 in the rotor core 21 can be secured, and as a result, the reluctance torque can be secured. The thickness T between the circumferential side surface 33 and the first constituent surface 31a in the direction orthogonal to the circumferential side surface 33 is formed so as to become thicker toward the inner side in the radial direction. Therefore, it is possible to increase the volume ratio of the permanent magnet 22 as compared with the case of using a conventional permanent magnet having a simple arc shape (both sides in the radial direction are parallel to each other), and as a result, the volume ratio of the permanent magnet 22 can be increased. The magnet torque can be improved. Further, since the volume of the permanent magnet 22 is increased in the vicinity of the circumferential end of the permanent magnet 22, it is possible to effectively suppress the demagnetization of the permanent magnet 22 by the external magnetic field in the vicinity of the circumferential end, and as a result. , The magnet torque can be effectively improved.

(2) The first constituent surface 31a has a shape that is recessed inward in the radial direction in the axial direction. As a result, the radial thickness of the magnet outer core portion 21b can be suitably secured, and as a result, the reluctance torque can be effectively improved.

(3) The length D1 of the circumferential side surface 33 in the direction along the virtual line Lv is set longer than the radial length D2 from the circumferential center 31c of the first radial side surface 31 to the outer peripheral surface of the rotor core 21. .. As a result, the thickness T between the circumferential side surface 33 and the first constituent surface 31a of the permanent magnet 22 can be made thicker. Therefore, it is possible to more effectively suppress the demagnetization of the permanent magnet 22 by the external magnetic field in the vicinity of the peripheral end portion, and as a result, the magnet torque can be further improved.

(4) The permanent magnet 22 has a magnetization orientation that intersects the circumferential side surface 33. That is, in this configuration in which the thickness T between the circumferential side surface 33 and the first constituent surface 31a of the permanent magnet 22 can be easily secured, the magnetic path intersecting the circumferential side surface 33 of the permanent magnet 22 can be long. As a result, the permeance between the circumferential side surface 33 of the permanent magnet 22 and the first constituent surface 31a is improved, and the demagnetization resistance in the portion is improved.

The above embodiment may be modified as follows.
-The magnetization orientation of the permanent magnet 22 in the above embodiment is an example, and may be, for example, a radial orientation or a parallel orientation other than the polar anisotropic orientation.

Further, the magnetization orientation may be as shown in FIG. As shown in the figure, the magnetization orientation of the permanent magnet 22 is set linearly, and on the extension line of the circumferential center line L2 (magnetic pole center line) of the permanent magnet 22 toward the stator 12 side (outer in the radial direction). It is set to go toward a certain point (magnetic flux concentration point F). Even with such a configuration, substantially the same effect as that of the above embodiment can be obtained.

-The dimensional setting of the permanent magnet 22 in the above embodiment is an example, and may be changed as appropriate. For example, the length D1 of the circumferential side surface 33 may be set to be the same as the radial length D2, or the length D1 of the circumferential side surface 33 may be set shorter than the radial length D2.

-In the above embodiment, the first constituent surface 31a has an arc shape that is recessed inward in the radial direction in the axial direction, but the entire first constituent surface 31a is located on the inner peripheral side of the virtual circle Cv. If so, it can be changed to a shape other than the arc shape. For example, the first constituent surface 31a may be configured by one or a plurality of planes. That is, the first constituent surface 31a may be formed in a plane shape orthogonal to the radial direction (circumferential center line L2). The second radial side surface 32 can be changed in the same manner.

In the above embodiment, the first radial side surface 31 is composed of the first constituent surface 31a and the pair of second constituent surfaces 31b, but the present invention is not limited to this, and for example, the first radial side surface 31 to the second configuration The surface 31b may be omitted, and the circumferential end of the first constituent surface 31a may be directly connected to the outer peripheral end of the circumferential side surface 33.

The number of poles of the rotor 14 and the number of slots of the stator 12 in the above embodiment are examples and can be changed as appropriate. For example, the number of poles of the rotor 14 and the number of slots may be appropriately changed so that the relationship between the number of poles of the rotor 14 and the number of slots is 2n: 3n (where n is a natural number). The relationship between the number of poles of the rotor 14 and the number of slots does not necessarily have to be 2n: 3n. For example, the relationship between the number of poles of the rotor 14 and the number of slots is configured to be 10:12, 14:12, or the like. May be good.

-In the above embodiment, it is applied to a brushless motor, but the present invention is not limited to this, and for example, it may be applied to a motor with a brush.
-The above-described embodiment and each modification may be combined as appropriate.

10 ... motor, 14 ... rotor, 13 ... rotating shaft, 21 ... rotor core, 22 ... permanent magnet, 31 ... first radial side surface, 31a ... first constituent surface (constituent surface), 32 ... second radial side surface, 33 ... Circumferential side surface, L1 ... Rotation axis, Pb ... Magnetic pole boundary, Lv ... Virtual line, Cv ... Virtual circle.

Claims (3)

The axis of rotation and
A substantially cylindrical rotor core fixed to the rotation axis so as to be integrally rotatable,
A rotor provided with a plurality of permanent magnets embedded at intervals in the circumferential direction inside the rotor core.
The permanent magnets are paired in the circumferential direction with the first radial side surface on the outer peripheral side and the second radial side surface on the inner peripheral side, which are paired in the radial direction, and the circumferential ends of the first and second radial side surfaces. Equipped with a pair of circumferential sides connecting the parts,
The circumferential side surface forms a straight line parallel to the virtual line connecting the magnetic pole boundary between the permanent magnets adjacent to each other in the circumferential direction and the rotation axis in the axial view.
The first radial side surface has a constituent surface located on the inner peripheral side of a virtual circle centered on a rotation axis and passing through an outer peripheral side end portion of the circumferential side surface.
The thickness between the circumferential side surface and the constituent surface in the direction orthogonal to the circumferential side surface is formed so as to become thicker toward the inner side in the radial direction .
The length of the circumferential side surface in the direction along the virtual line is set to be longer than the radial length from the circumferential center of the first radial side surface to the outer peripheral surface of the rotor core.
The permanent magnet has a polar anisotropic orientation that curves so that the inside in the radial direction becomes convex from the permanent magnet of the S pole toward the permanent magnet of the adjacent N pole, and is a magnetization orientation that intersects the circumferential side surface. A rotor characterized by having . In the rotor according to claim 1,
The rotor is characterized in that the constituent surface has a shape of being recessed inward in the radial direction in the axial direction. A motor comprising the rotor according to claim 1 or 2 .

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