JP2023156760A - rotor - Google Patents

Abstract

To provide a rotor that can improve the demagnetization resistance of a Halbach array magnet.SOLUTION: A permanent magnet 22 of a Halbach array magnet rotor 12 is configured such that the surface side portion of a stator 11 that is likely to receive the magnetic flux φ2 in the opposite direction, which is a cause of demagnetization of the q-axis magnet portion 22q, that is, a portion near the outer surface 22b, which is the portion close to the stator 11 side have at least a high coercive force Hc. As an example, the q-axis magnet portion 22q is configured to have a uniformly high coercive force Hc throughout itself.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to rotors with permanent magnets.

2. Description of the Related Art A motor rotor is known in which a plurality of permanent magnets are arranged on the side surface of a rotor base as a magnetic pole part. The permanent magnet is, for example, a Halbach array magnet (see, for example, Patent Document 1). By using Halbach array magnets, motor performance can be expected to improve.

Japanese Patent Application Publication No. 2020-137387

A Halbach array magnet is a magnet formed by alternately arranging in the circumferential direction d-axis magnet portions in which magnetic flux is primarily directed in the radial direction and q-axis magnet portions in which magnetic flux is primarily directed in the circumferential direction. Furthermore, the d-axis magnet sections on both sides of the q-axis magnet section have different polarities. Due to the structure of such a magnet, the magnetic flux emitted from the d-axis magnet section on one side in the circumferential direction of the q-axis magnet section passes through the stator core on the stator side, etc., and returns to the d-axis magnet section on the other side in the circumferential direction. A small loop-shaped magnetic path is formed between the permanent magnets of the rotor, which are made of Halbach array magnets, and the stator, straddling each other.

However, in this case, the magnetic flux directed in the circumferential direction on the stator side is opposite to the magnetic flux directed in the circumferential direction of the q-axis magnet portion on the rotor side. Since the q-axis magnet section that constitutes the Halbach array magnet is arranged close to the stator side, magnetic flux generated in the opposite direction on the stator side is one of the factors that demagnetizes the q-axis magnet section.

An object of the present disclosure is to provide a rotor that can improve the demagnetization resistance of Halbach array magnets.

A rotor that solves the above problem includes a rotor base (21) and a plurality of permanent magnets (22) arranged in a circumferential direction on a side surface (21a) of the rotor base, and the permanent magnets have a magnetic flux mainly in a radial direction. It is composed of Halbach array magnets in which the d-axis magnet portions (22dn, 22ds) which face the magnetic flux mainly and the q-axis magnet portions (22q, 22q1, 22q2) whose magnetic flux mainly faces the circumferential direction are arranged alternately in the circumferential direction. In the rotor (12), the q-axis magnet portion of the permanent magnet has a coercive force (Hc) of at least its surface side portion (22b) set higher than that of the d-axis magnet portion.

According to the rotor, the permanent magnets employing the Halbach array magnets have a higher coercive force at the surface side portion of the q-axis magnet portion, that is, the portion closer to the stator side than the d-axis magnet portion. For example, if the d-axis magnet part is set to have a generally assumed coercive force, the q-axis magnet part has a higher coercive force. Therefore, even if the q-axis magnet section receives magnetic flux in the opposite direction from the stator side, which is a cause of concern as a cause of demagnetization of the q-axis magnet section, the q-axis magnet section, which has a high coercive force, can exhibit the desired magnetic performance. In other words, the anti-demagnetization performance of the permanent magnet can be improved, and the permanent magnet as a whole can contribute to exhibiting desired magnetic performance.

FIG. 1 is a configuration diagram of a motor having a rotor in one embodiment. It is a perspective view of the rotor in the same embodiment. It is a partially enlarged view of the rotor in the same embodiment. It is an explanatory view for explaining the composition of the permanent magnet in the same embodiment. It is an explanatory view for explaining the composition of the permanent magnet in a modification. It is an explanatory view for explaining the composition of the permanent magnet in another modification.

An embodiment of the rotor will be described below.
(Configuration of motor 10)
As shown in FIG. 1, the motor 10 of this embodiment includes a stator 11 and a rotor 12. The stator 11 has a substantially annular shape. The stator 11 has, for example, 24 coil magnetic pole portions (not shown) in the circumferential direction. A rotor 12 is rotatably arranged inside the stator 11. The stator 11 generates a rotating magnetic field for rotationally driving the rotor 12 based on energization of its own coil magnetic pole portion. The motor 10 of this embodiment is intended to be applied to a high-speed rotation motor with a maximum rotation speed of 12,000 [rpm] or more, as an example.

(Configuration of rotor 12)
As shown in FIGS. 1 and 2, the rotor 12 of this embodiment includes a rotor base 21, a permanent magnet 22, and a scattering prevention member 23.

The rotor base 21 has a generally cylindrical shape as a whole. The rotor base 21 has a hollow structure in consideration of weight reduction and the like. An axial end portion of the rotor base portion 21 is integrally configured as an output shaft portion 21x. For example, twenty permanent magnets 22 are arranged in the circumferential direction on the outer surface 21a of the axially central portion of the rotor base 21. The outer surface 21a of the rotor base 21 of this embodiment has 20 flat surfaces corresponding to each permanent magnet 22 (see FIG. 3). The rotor 12 has 20 magnetic pole parts in the circumferential direction.

The permanent magnet 22 has a substantially rectangular shape. The inner surface 22a of the permanent magnet 22 on the inner diameter side of the rotor 12 is in contact with the outer surface 21a of the rotor base 21. The inner surface 22a of the permanent magnet 22 is a flat surface, and the flat surfaces are in contact with the outer surface 21a of the rotor base 21. The outer surface 22b of the permanent magnet 22, which is on the outer diameter side of the rotor 12, constitutes a uniform outer circumferential surface of the rotor 12 by all the permanent magnets 22 in the circumferential direction. Side end surfaces 22c on both sides of the permanent magnet 22 in the circumferential direction of the rotor 12 form flat surfaces along the radial direction of the rotor 12. In order to bring the inner surface 22a of the permanent magnet 22 into contact with the rotor base 21, the permanent magnet 22 has a gap at each side end surface 22c on both sides with respect to the permanent magnet 22 on both sides in the circumferential direction, or has a gap between only one side end surface 22c. It is in contact. In each figure, the permanent magnets 22 are drawn in contact with each other.

As shown in FIG. 3, the permanent magnet 22 is constituted by a Halbach array magnet in this embodiment. Specifically, the permanent magnet 22 is divided into three regions with different magnetization modes in the circumferential direction. Both sides of the permanent magnet 22 in the circumferential direction are d-axis magnet parts 22dn and 22ds in which the magnetic flux is mainly oriented in the radial direction. The circumferential central portion of the permanent magnet 22 is a q-axis magnet portion 22q in which the magnetic flux is mainly directed in the circumferential direction and directed toward the d-axis magnet portions 22dn and 22ds on both sides thereof. In the permanent magnet 22, the d-axis magnet parts 22dn, 22ds and the q-axis magnet part 22q are integrally formed as one magnet material.

In the d-axis magnet portion 22dn on one side in the circumferential direction, an N pole appears on the outer surface 22b of the permanent magnet 22. In the d-axis magnet section 22ds on the other side in the circumferential direction, an S pole appears on the outer surface 22b of the permanent magnet 22. The arrangement of the permanent magnets 22 in the rotor 12 in the circumferential direction is such that the d-axis magnet portions 22dn of the same polarity of the permanent magnets 22 adjacent to each other in the circumferential direction are arranged in a row. The d-axis magnet parts 22dn of the same polarity cooperate with each other to form a magnet pole part of the same polarity.

Incidentally, regarding the manner in which the permanent magnets 22 are attached to the outer surface 21a of the rotor base 21, for example, after attaching the permanent magnets 22 to every other part of the circumference or part of the circumference, the permanent magnets 22 are attached between the previously attached permanent magnets 22. A post-installed permanent magnet 22 is inserted from the radial direction. The attachment of each permanent magnet 22 is repeated over the entire circumference of the rotor 12. Further, the radially inner portion 22e of each permanent magnet 22 has sloped surfaces 22f at both corners in the circumferential direction, and has a tapered shape that can be easily inserted between the previously attached permanent magnets 22. Further, each inclined surface 22f is located at the corner of each d-axis magnet section 22dn, 22ds of the permanent magnet 22, but each d-axis magnet section 22dn, 22ds is inclined so that its own internal magnetic flux follows each inclined surface 22f. Since the permanent magnet 22 is magnetized in a manner that

Further, as shown in FIG. 4, the q-axis magnet portion 22q of each permanent magnet 22 of this embodiment is configured to have a high coercive force Hc. In this case, the q-axis magnet section 22q has a higher coercive force Hc than the d-axis magnet sections 22dn and 22ds. In other words, the d-axis magnet sections 22dn and 22ds have a relatively low coercive force Hc with respect to the q-axis magnet section 22q, but in this embodiment, the coercive force Hc is generally assumed. Further, the q-axis magnet section 22q of this embodiment is configured so that the entire body has a uniformly high coercive force Hc.

As shown in FIG. 2, the anti-scattering member 23 is attached so as to revolve around the rotor 12 along the outer surfaces 22b of the plurality of permanent magnets 22 in the circumferential direction. The scattering prevention member 23 is provided, for example, in a cylindrical shape so as to completely cover the permanent magnet 22. For example, a carbon fiber reinforced resin material (referred to as CFRP material) is used for the scattering prevention member 23. A ribbon-shaped material of CFRP material (not shown) is wound several times around the permanent magnet 22 of the rotor 12, and is wound in one layer or in multiple layers. Then, heat curing is performed to produce a cylindrical anti-scattering member 23 that fixes the permanent magnet 22 and prevents it from scattering.

(Action of this embodiment)
The operation of this embodiment will be explained.
In the rotor 12 of this embodiment, the permanent magnets 22 are configured as Halbach array magnets. As shown in FIG. 4, the magnetic flux emitted from the d-axis magnet section 22dn on one side in the circumferential direction of the q-axis magnet section 22q passes through the stator core (not shown) on the stator 11 side, etc., and reaches the d-axis magnet section on the other side in the circumferential direction. Return to section 22ds. A small loop-shaped magnetic path is formed between the permanent magnets 22 of the rotor 12 and the stator 11 so as to straddle each other. At this time, the magnetic flux φ2 directed in the circumferential direction on the stator 11 side is opposite to the magnetic flux φ1 directed in the circumferential direction of the q-axis magnet portion 22q on the rotor 12 side. Since the q-axis magnet portion 22q forming the Halbach array magnet is arranged close to the stator 11 side, the magnetic flux φ2 generated in the opposite direction on the stator 11 side becomes one of the factors that demagnetize the q-axis magnet portion 22q. It is something.

In consideration of such concerns, the permanent magnet 22 of the present embodiment is configured such that the q-axis magnet portion 22q has a high coercive force Hc to improve demagnetization resistance. Therefore, even when receiving the magnetic flux φ2 in the opposite direction generated by the stator 11, the q-axis magnet portion 22q can exhibit the desired magnetic performance, and by extension, the entire permanent magnet 22 can exhibit the desired magnetic performance.

(Effects of this embodiment)
The effects of this embodiment will be explained.
(1) In the permanent magnets 22 of the rotor 12 of this embodiment that employs Halbach array magnets, the coercive force Hc of the q-axis magnet portion 22q is set higher than that of the d-axis magnet portions 22dn and 22ds. In this embodiment, the coercive force Hc is uniformly applied to the entire q-axis magnet part 22q so as to include the surface side part of the q-axis magnet part 22q, that is, the part near the outer surface 22b which is a part close to the stator 11 side. is high. If the d-axis magnet sections 22dn and 22ds are set to, for example, a commonly assumed coercive force Hc, the q-axis magnet section 22q has a higher coercive force Hc. Therefore, even when receiving magnetic flux φ2 in the opposite direction from the stator 11 side, which is a concern as a cause of demagnetization of the q-axis magnet part 22q, the q-axis magnet part 22q, which has a high coercive force Hc, can exhibit the desired magnetic performance. I can do it. In other words, the anti-demagnetization performance of the permanent magnet 22 can be improved, and the permanent magnet 22 as a whole can contribute to exhibiting desired magnetic performance.

(2) The q-axis magnet part 22q of the permanent magnet 22 is configured to uniformly increase the coercive force Hc not only in the part near the outer surface 22b, which is the part close to the stator 11 side, but also in the whole itself. Easy to manufacture with one magnet material.

(3) The permanent magnet 22 is integrally constructed as a single magnet material with the q-axis magnet section 22q located at the center in the circumferential direction and the d-axis magnet sections 22dn and 22ds located at both sides in the circumferential direction. used. In other words, by appropriately combining the permanent magnets 22 into one magnet material, it is expected that the permanent magnets 22 can be easily attached to the rotor 12.

(Example of change)
This embodiment can be modified and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- The various numerical values described above are just examples, and may be changed as appropriate.
- The q-axis magnet part 22q of the above-mentioned permanent magnet 22 has a structure in which the coercive force Hc is uniformly increased not only in the part near the outer surface 22b which is the surface side part but also in the whole itself, but it is not limited to this. .

For example, the q-axis magnet section 22q1 shown in FIG. 5 has two parts: a front side part A1 and a back side part A2. The front side portion A1 and the back side portion A2 are made of different magnetic materials and are combined with each other. The coercive force Hc of the front side portion A1 is set higher than that of the back side portion A2 and higher than that of the d-axis magnet portions 22dn and 22ds. In other words, the back side portion A2 has a relatively lower coercive force Hc than the front side portion A1, but is set to a commonly assumed coercive force Hc, for example. In the permanent magnet 22 of this embodiment, the surface side portion A1 of the q-axis magnet portion 22q1 forming the outer surface 22b, which is a portion close to the stator 11 side, has a partially high coercive force Hc. This is an example of effectively utilizing a magnetic material having a high coercive force Hc.

Further, in the q-axis magnet portion 22q2 shown in FIG. 6, the coercive force Hc is set to be higher as it goes from the center portion B1 to the peripheral portion B2. The coercive force Hc of the peripheral portion B2 is set higher than that of the d-axis magnet portions 22dn and 22ds. In the permanent magnet 22 of this embodiment, the peripheral edge B2 of the q-axis magnet portion 22q2 forming the outer surface 22b, which is a portion close to the stator 11 side, has a partially high coercive force Hc. During the manufacturing process of the magnetic material, which includes adding, for example, dysprosium (Dy), a heavy rare earth element, to increase its own coercive force, the coercive force Hc of the peripheral portion B2 tends to become higher than that of the central portion B1. In particular, this phenomenon occurs significantly depending on the size of the magnet material, etc., and this is an example of a case where it is difficult to make the coercive force Hc uniform throughout the magnet material.

- The shape of the permanent magnet 22 is an example, and may be changed as appropriate. For example, the permanent magnet 22 does not need to be provided with the inclined surface 22f. Furthermore, the inner surface 22a of the permanent magnet 22 may be a circumferential surface. In this case, the shape of the outer surface 21a of the rotor base 21 is also changed.

- Although the anti-scattering member 23 is provided so as to cover the entire permanent magnet 22, it may be configured so that a portion of the permanent magnet 22 is exposed. Moreover, the scattering prevention member 23 may be omitted.
- In addition, the configuration of the rotor 12 may be changed as appropriate.

- Although applied to an inner rotor type in which the rotor 12 is located radially inside the stator 11, it may also be applied to an outer rotor type in which the rotor 12 is located radially outside the stator 11.
- Although the present invention has been applied to a radial type in which the rotor 12 and the stator 11 face each other in the radial direction, it may also be applied to an axial type in which the rotor and the stator face each other in the axial direction.

(Additional note)
The technical ideas that can be understood from the above embodiment and modification examples will be described.
(a) A rotor base (21) and a plurality of permanent magnets (22) arranged in the circumferential direction of the side surface (21a) of the rotor base, the permanent magnets being d-axis magnets whose magnetic flux is mainly directed in the radial direction. (22dn, 22ds) and q-axis magnet parts (22q, 22q1, 22q2) whose magnetic flux mainly points in the circumferential direction are arranged alternately in the circumferential direction. ,
A motor (10) comprising a stator (11) that generates a rotating magnetic field for rotationally driving the rotor,
The q-axis magnet portion of the permanent magnet in the rotor has a coercive force (Hc) of at least its surface side portion (22b) set higher than that of the d-axis magnet portion;
motor.

12 rotor, 21 rotor base, 21a outer surface (side surface), 22 permanent magnet, 22b outer surface (surface side part), 22dn, 22ds d-axis magnet section, 22q, 22q1, 22q2 q-axis magnet section, Hc coercive force

Claims (5)

a rotor base (21);
A plurality of permanent magnets (22) arranged in the circumferential direction of the side surface (21a) of the rotor base,
The permanent magnet has d-axis magnet parts (22dn, 22ds) whose magnetic flux mainly faces the radial direction and q-axis magnet parts (22q, 22q1, 22q2) whose magnetic flux mainly faces the circumferential direction, which are alternately arranged in the circumferential direction. A rotor (12) composed of Halbach array magnets,
The q-axis magnet portion of the permanent magnet has a coercive force (Hc) of at least its surface side portion (22b) set higher than that of the d-axis magnet portion;
Rotor. The q-axis magnet portion (22q) of the permanent magnet is configured such that the coercive force is uniformly high throughout itself;
A rotor according to claim 1. The q-axis magnet part (22q1) of the permanent magnet has two parts, a front side part (A1) and a back side part (A2), and the coercive force of the front side part is higher than that of the back side part. is set high,
A rotor according to claim 1. The q-axis magnet part (22q2) of the permanent magnet is configured such that the coercive force increases from the center part (B1) to the peripheral part (B2) of the permanent magnet.
A rotor according to claim 1. The permanent magnet is integrally constructed as a single magnet material, with the q-axis magnet section located at the center in the circumferential direction and the d-axis magnet sections located at both sides in the circumferential direction.
A rotor according to claim 1.

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