JP7172686B2 - Permanent magnet rotor - Google Patents

Description

The present disclosure relates to permanent magnet rotors used in electric motors.

Patent Document 1 discloses a permanent magnet rotor having a plurality of permanent magnets and a plurality of core pieces. The plurality of permanent magnets has a first permanent magnet arranged between the two core pieces and a second permanent magnet arranged on both sides of the two core pieces. The first permanent magnet is radially magnetized and the second permanent magnet is circumferentially magnetized. One side of the core piece on each side of the first permanent magnet is exposed to the rotor surface and the other side is in contact with the sides of the first and second permanent magnets. A contact surface between the second permanent magnet and the core piece extends in the radial direction. The core piece is formed so that the area of the contact surface in contact with the second permanent magnet is larger than the surface area of the core piece appearing on the rotor surface.

Japanese Patent No. 5194984

In the structure of the conventional permanent magnet type rotor described above, if an attempt is made to further increase the torque, the core piece contacting the second permanent magnet is required to increase the magnetic flux density on the surface of the core piece appearing on the outer peripheral surface of the rotor. It becomes necessary to increase the area of the contact surface. However, such an increase in the area of the contact surface means an increase in the radial dimension of the core pieces, so there is a problem that the weight of the rotor may increase excessively. Therefore, a technique for increasing the magnetic flux density of the rotor with a structure different from the above-described conventional technique is desired.

According to one aspect of the present disclosure, a rotor (100) of permanent magnet type is provided. This rotor comprises a hollow cylindrical rotor core (110) made of a ferromagnetic core material, and a plurality of magnetic poles (130N, 130S) held by the rotor core and forming a plurality of magnetic poles (130N, 130S) on the outer peripheral surface of the rotor. and permanent magnets (121-124). Among the plurality of permanent magnets, a permanent magnet group (120) forming one magnetic pole is composed of a first magnet (121) magnetized in the radial direction of the rotor, and a magnetic pole positioned inside the rotor core relative to the first magnet. A second magnet (122) is arranged and magnetized in the radial direction of the rotor, and is arranged on both sides of the first magnet so as to increase the magnetic flux density of the first magnet on the outer peripheral surface of the rotor. , a third magnet (123) magnetized in the circumferential direction of the rotor, and a fourth magnet (124) arranged on both sides of the second magnet and magnetized in the circumferential direction of the rotor. . The rotor core is continuous along a magnetic path from a portion between the first magnet and the second magnet to an outer peripheral surface of the rotor via a portion between the third magnet and the fourth magnet. It has a common core portion (112) that

According to this permanent magnet rotor, when receiving a magnetic field from the armature (stator), the armature magnetic flux tends to flow in the common core portion, and this armature magnetic flux causes the direction of the magnet magnetic flux to tilt and flow to the core surface. Therefore, the magnetic flux density on the outer peripheral surface of the rotor can be increased.

1 is a cross-sectional view showing the configuration of a permanent magnet motor according to a first embodiment; FIG. Partially enlarged view of the permanent magnet rotor. FIG. 4 is an explanatory diagram showing the magnetic flux of the magnetic poles in a state where there is no armature magnetic flux; Explanatory drawing which shows the magnetic flux of a magnetic pole in a state with an armature magnetic flux. FIG. 5 is an explanatory diagram showing the configuration of a permanent magnet rotor according to a second embodiment;

A. First embodiment:
As shown in FIG. 1, the permanent magnet motor 300 of the first embodiment includes a permanent magnet rotor 100 and a stator 200. As shown in FIG. Below, the permanent magnet type rotor 100 is simply referred to as "rotor 100".

The rotor 100 includes a rotor core 110 made of a ferromagnetic core material, and a permanent magnet group 120 held in the rotor core 110 and forming a plurality of magnetic poles on the outer peripheral surface of the rotor 100 . Rotor core 110 is formed by laminating a plurality of core materials formed as disc-shaped or annular core sheets, and has a hollow cylindrical shape as a whole. The core material is usually made of a soft magnetic material. Permanent magnet group 120 is held within rotor core 110 by a core material. As will be described later, the permanent magnet group 120 forming one pole includes a first magnet 121, a second magnet 122, a third magnet 123, and a fourth magnet . The multiple first magnets 121 in the rotor 100 are arranged at rotationally symmetrical positions about the central axis CX of the rotor 100 . The same applies to the other magnets 122-124. The arrangement and dimensions of the magnets 121 to 124 forming one pole will be described later.

Stator 200 is arranged across a rotor gap from the outer peripheral surface of rotor 100 and has a stay core 210 provided with a plurality of slots 220 and an electromagnetic coil 230 accommodated in each slot 220 .

In the example of FIG. 1, rotor 100 has 12 magnetic poles and stator 200 has 36 slots, but these can be set to any desired value. Further, the rotor 100 of the first embodiment is an embedded magnet type rotor in which permanent magnets are embedded in the rotor core 110, but in the present disclosure, part of the permanent magnets are exposed on the surface of the rotor core 110. It can also be applied to a surface magnet type rotor.

As shown in FIG. 2, a plurality of magnetic poles 130N and 130S are formed on the outer peripheral surface of the rotor 100. As shown in FIG. The first magnetic pole 130N is the north pole and the second magnetic pole 130S is the south pole. These magnetic poles 130N and 130S are arranged alternately.

A permanent magnet group forming one magnetic pole 130N includes a first magnet 121, a second magnet 122, a third magnet 123, and a fourth magnet . A white arrow drawn on each of the magnets 121 to 124 indicates the direction of magnetization. The first magnet 121 is magnetized in a direction parallel to the radial direction of the rotor 100 . The magnetization direction of the first magnet 121 forming the magnetic pole 130N is the direction outward from the central axis CX of the rotor 100 . The second magnets 122 are arranged inside the rotor core 110 relative to the first magnets 121 and are magnetized in the same direction as the first magnets 121 . Note that “inside the rotor core 110 relative to the first magnet 121 ” means a position closer to the central axis CX of the rotor 100 . The third magnets 123 are arranged on both sides of the first magnet 121, and are magnetized in a direction parallel to the circumferential direction of the rotor 100 so as to increase the magnetic flux density on the outer peripheral surface of the rotor 100 by the first magnets 121. It is The magnetization direction of the third magnet 123 constituting the magnetic pole 130N is the direction from the third magnet 123 to the first magnet 121 . The magnetization directions of the two third magnets 123 arranged on both sides of the first magnet 121 are opposite to each other. “Arranged on both sides of the first magnet 121 ” means arranged at positions adjacent to the first magnet 121 along the circumferential direction of the rotor 100 . The fourth magnets 124 are arranged on both sides of the second magnet 122 and are magnetized in the same second direction as the third magnet 123 . The magnetization directions of the two fourth magnets 124 provided on both sides of the second magnet 122 are also opposite to each other. A part of the fourth magnet 124 also functions as a magnet that constitutes the second magnetic pole 130S. That is, one of two portions obtained by virtually cutting the fourth magnet 124 along a plane parallel to the radial direction and the central axis direction of the rotor 100 constitutes the first magnetic pole 130N, and the other constitutes the second magnetic pole. can be considered to constitute the magnetic pole 130S of

In FIG. 2, the magnets 121 to 124 forming the second magnetic pole 130S are shown with circumferential dimensions W121 to W124 and radial dimensions H121 to H124, respectively. In this specification, the “circumferential dimension” of a certain magnet is represented by an angle [radian] when both ends of the magnet are viewed from the central axis CX of the rotor 100 . For example, if a magnet has a 1/12 toric shape, the circumferential dimension of the magnet is π/6. Also, the “radial dimension” of a certain magnet is represented by the length of that magnet measured along a radius extending radially outward from the central axis CX of the rotor 100 .

A circumferential dimension W122 of the second magnet 122 is larger than a circumferential dimension W121 of the first magnet 121 . In addition, the circumferential dimension W122 of the second magnet 122 is larger than the circumferential dimension (W121+2×W123) of the first magnet 121 and the two third magnets 123 on both sides thereof. A radial dimension H123 of the third magnet 123 is larger than a radial dimension H121 of the first magnet 121 . The sides of the first magnet 121 are respectively covered by the sides of the third magnets 123 on both sides of the first magnet 121 . This is because the third magnet 123 sufficiently increases the magnetic flux density of the first magnet 121 . Here, the “side surface” of each magnet means a surface parallel to the radial direction and the central axis direction of rotor 100 . A radial dimension H124 of the fourth magnet 124 is larger than a radial dimension H122 of the second magnet 122 . This is also for sufficiently increasing the magnetic flux density of the second magnet 122 by the fourth magnet 124 . Note that the circumferential dimension W124 of the fourth magnet 124 can be set arbitrarily. Note that the arrangement and dimensional relationships of these magnets 121 to 124 are only examples, and other arrangements and dimensions may be set.

The second magnetic pole 130S also has the same magnet structure as the first magnetic pole 130N, but the magnetization direction of each magnet is opposite to the magnetization direction of the first magnetic pole 130N described above.

Rotor core 110 extends from the portion between first magnet 121 and second magnet 122 to the outer peripheral surface of rotor 100 via the portion between third magnet 123 and fourth magnet 124 along the magnetic path. It has a continuous common core portion 112 . The portion between the third magnet 123 and the fourth magnet 124 is continuous with both sides of the portion between the first magnet 121 and the second magnet 122, respectively. Therefore, the common core portion 112 and its entire magnetic path have a substantially U-shaped bent shape. A portion of common core portion 112 between third magnet 123 and fourth magnet 124 is exposed on the outer peripheral surface of rotor 100 .

In the first embodiment, the dimensions of the common core portion 112 are also devised. Specifically, among the dimensions of the common core portion 112, the first dimension L1 of the common core portion 112 corresponding to the distance between the first magnet 121 and the second magnet 122 is greater than the second dimension L2 of the common core portion 112 corresponding to the distance between the magnets 124; The advantages of this configuration are as follows. That is, in the common core portion 112, since the magnetic flux concentrates at the bent portions of the common core portion 112, magnetic saturation is likely to occur there. As described above, if the first dimension L1 is made larger than the second dimension L2, the dimension L1 of the common core portion 112 corresponding to the distance between the first magnet 121 and the second magnet 122 is increased. , magnetic saturation can be made difficult to occur in the bent portion of the common core portion 112 . As a result, the magnetic flux density on the outer peripheral surface of rotor 100 can be increased. However, the first dimension L1 may be less than or equal to the second dimension L2.

Rotor core 110 preferably further includes an outer core portion 114 that covers the outside of first magnet 121 and third magnet 123 and an inner core portion 116 that covers the inside of second magnet 122 and fourth magnet 124 . The outer core portion 114 has a function of increasing the magnetic flux density on the outer peripheral side of the first magnet 121 . Inner peripheral core portion 116 has a function of increasing the mechanical strength of rotor 100 .

The third magnet 123 is arranged in contact with both side surfaces of the first magnet 121 . Also, the radial dimension H123 of the third magnet 123 is greater than or equal to the radial dimension H121 of the first magnet 121 . According to this configuration, the magnetic flux density of the first magnet 121 can be further increased by the third magnet 123, and a phenomenon in which the magnetic flux density of the first magnet 121 does not become sufficiently high due to magnetic saturation can be prevented. However, the third magnet 123 may be arranged without being in contact with both side surfaces of the first magnet 121 .

The fourth magnet 124 is not in contact with both side surfaces of the second magnet 122 and is spaced apart. However, it is preferable that the fourth magnet 124 is arranged in contact with both side surfaces of the second magnet 122 . At this time, the radial dimension H124 of the fourth magnet 124 is preferably equal to or greater than the radial dimension H122 of the second magnet 122 . According to this preferred configuration, the magnetic flux density of the second magnet 122 can be further increased by the fourth magnet 124, and a phenomenon in which the magnetic flux density of the second magnet 122 does not become sufficiently high due to magnetic saturation can be prevented.

As shown in FIG. 3, in the first magnetic pole 130N, when there is no armature magnetic flux, the outward magnetic flux Ψ122 from the second magnet 122 converges toward the first magnet 121 and the third magnet 123. . The term “armature magnetic flux” means magnetic flux that tends to flow when a current is applied to the electromagnetic coils 230 of the stator 200 . Magnetic flux generated by permanent magnets is called "magnet magnetic flux". A magnetic flux Ψ 124 directed from the fourth magnet 124 to the third magnet 123 is parallel to the circumferential direction or converges toward the third magnet 123 . A magnetic flux Ψ121 directed outward from the first magnet 121 is substantially parallel to the radial direction of the rotor 100 . Further, on the exposed surface of common core portion 112 exposed on the outer peripheral surface of rotor 100, no magnetic flux is generated toward the rotor gap. In this way, when there is no armature magnetic flux, the only magnetic flux directed toward the rotor gap in the first magnetic pole 130N is the magnetic flux Ψ121 caused by the first magnet 121, and the generated area of the magnetic flux directed toward the rotor gap is small. The magnetic flux density of the entire magnetic pole 130N of 1 is in a low state. This also applies to the second magnetic pole 130S. It should be noted that the fact that the area where the magnetic flux toward the rotor gap is generated is small in the absence of the armature magnetic flux also means that the no-load induced voltage can be suppressed. That is, the rotor 100 of the first embodiment also has the advantage of being able to suppress the no-load induced voltage.

As shown in FIG. 4, when the armature magnetic flux Ψac indicated by the white arrow is about to flow, the substantial magnetic flux of the first magnetic pole 130N is the armature magnetic flux Ψac and each magnet described in FIG. and the magnetic flux due to At this time, the substantial magnetic flux of the first magnetic pole 130N is generated in the direction indicated by the solid line and broken line arrows in FIG. As a result, magnetic flux is generated not only from the first magnet 121 toward the rotor gap, but also from the exposed surface of the common core portion 112 toward the rotor gap. As a result, when the armature magnetic flux is about to flow, the magnetic flux generation area toward the rotor gap increases, and the magnetic flux density of the entire first magnetic pole 130N increases. This also applies to the second magnetic pole 130S. Therefore, by providing the common core portion 112, it is possible to increase the magnetic flux density without excessively increasing the weight of the rotor. The reason why the direction of the magnetic flux from the first magnet 121 toward the rotor gap is inclined in FIG. because they try.

As described above, according to the rotor 100 of the first embodiment, when receiving the magnetic field from the armature (stator), the armature magnetic flux Ψac tends to flow in the common core portion 112, and the armature magnetic flux Ψac causes the magnet magnetic flux is tilted and tends to flow to the core surface, the magnetic flux density on the outer peripheral surface of the rotor 100 can be increased.

B. Second embodiment:
As shown in FIG. 5, the rotor 100a of the second embodiment has a configuration in which the first magnet 121, the second magnet 122, and the fourth magnet 124 of the first embodiment are each divided into two. The configuration is the same as that of the first embodiment. Note that the same reference numerals as in the first embodiment indicate the same configurations, and refer to the preceding description.

A first core portion C1 exists between the first portion 121a and the second portion 121b of the first magnet 121 divided into two. This first core portion C1 is a part of rotor core 110 . By providing the first core portion C1 between the first portion 121a and the second portion 121b of the first magnet 121, the strength of the entire rotor can be increased by the first core portion C1, and the rotor can withstand high-speed rotation. It is possible.

Similarly, a second core portion C2 exists between the first portion 122a and the second portion 122b of the second magnet 122 divided into two. This second core portion C2 is also a part of rotor core 110 . By providing the second core portion C2 between the first portion 122a and the second portion 122b of the second magnet 122, the strength of the entire rotor can be increased by the second core portion C2, and the rotor can withstand high-speed rotation. It is possible.

The dimension W2 of the second core portion C2 along the circumferential direction of the rotor 100 is preferably larger than the dimension W1 of the first core portion C1. Since the second core portion C2 is located inside the rotor core 110 relative to the first core portion C1, it has a role of holding a greater weight than the first core portion C1 when the rotor 100 rotates, and thus has a greater weight than the first core portion C1. It will take more force. Therefore, by making the circumferential dimension W2 of the second core portion C2 larger than the circumferential dimension W1 of the first core portion C1, it is possible to withstand higher-speed rotation. Further, if the circumferential dimension W1 of the first core portion C1 is made smaller, there is also an advantage that a decrease in the magnetic flux density due to division of the first magnet 121 can be suppressed.

The first portion 124a and the second portion 124b of the fourth magnet 124 are adjacent to each other along the circumferential direction of the rotor 100, and a core portion C4, which is a part of the rotor core forming the rotor core 110, exists between them. do. A first portion 124a of the fourth magnet 124 constitutes a first magnetic pole 130N, and a second portion 124b of the fourth magnet 124 constitutes a second magnetic pole 130S adjacent to the first magnetic pole 130N. According to this configuration, since the core portion C4 exists between the first portion 124a and the second portion 124b of the fourth magnet 124, when the magnetic field from the armature (stator) is received, the core portion C4 also rotates. The armature magnetic flux causes the magnetic flux of the magnet to incline and tends to flow to the core surface, so that the magnetic flux density on the outer peripheral surface of the rotor 100 can be further increased.

The rotor 100a of the second embodiment has a configuration in which the first magnet 121, the second magnet 122, and the fourth magnet 124 of the first embodiment are each divided into two. Only one or two of 121, 122, 124 may be split. Also, the number of divisions of each magnet is not limited to 2, and can be set to any number of 3 or more.

The present disclosure is not limited to the embodiments and modifications described above, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, the technical features in the embodiments and modifications corresponding to the technical features in each form described in the Summary of the Disclosure column can be used to solve some or all of the above problems, or In order to achieve some or all of the effects, it is possible to appropriately replace or combine them. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 100,100a...Permanent magnet type rotor 110...Rotor core 112...Common core part 120...Permanent magnet group 121...First magnet 121a...First part of the first magnet 121b...Second part of the first magnet , 122... Second magnet 122a... First part of second magnet 122b... Second part of second magnet 123... Third magnet 124... Fourth magnet 124a... First part of fourth magnet 124b ... the second part of the fourth magnet

Claims (8)

A permanent magnet rotor (100, 100a),
a hollow cylindrical rotor core (110) made of a ferromagnetic core material;
a plurality of permanent magnets (121 to 124) held by the rotor core and forming a plurality of magnetic poles (130N, 130S) on the outer peripheral surface of the rotor;
with
Among the plurality of permanent magnets, the permanent magnet group constituting one magnetic pole is
first magnets (121, 121a, 121b) magnetized in the radial direction of the rotor;
second magnets (122, 122a, 122b) arranged inside the rotor core relative to the first magnets and magnetized in the radial direction of the rotor;
third magnets (123) arranged on both sides of the first magnet and magnetized in the circumferential direction of the rotor so as to increase the magnetic flux density of the first magnet on the outer peripheral surface of the rotor;
fourth magnets (124, 124a, 124b) arranged on both sides of the second magnet and magnetized in the circumferential direction of the rotor;
including
The rotor core is continuous along a magnetic path from a portion between the first magnet and the second magnet to an outer peripheral surface of the rotor via a portion between the third magnet and the fourth magnet. a rotor having a common core portion (112) that A rotor according to claim 1, wherein
The third magnet is arranged in contact with both side surfaces of the first magnet,
The rotor, wherein the radial dimension (H123) of the third magnet is greater than or equal to the radial dimension (H121) of the first magnet. 3. The rotor according to claim 1 or 2,
The fourth magnet is arranged in contact with both side surfaces of the second magnet,
The rotor, wherein the radial dimension (H124) of the fourth magnet is greater than or equal to the radial dimension (H122) of the second magnet. The rotor according to any one of claims 1 to 3,
The fourth magnet is divided into a first portion (124a) and a second portion (124b) that are adjacent to each other along the circumferential direction of the rotor, and the first portion of the fourth magnet crosses the first magnetic pole. said second portion of said fourth magnet constitutes another magnetic pole adjacent to said one magnetic pole; and between said first portion and said second portion of said fourth magnet is a portion of said rotor core A rotor in which (C4) exists. The rotor according to any one of claims 1 to 4,
The first magnet is divided into a first portion (121a) and a second portion (121b) that are adjacent to each other along the circumferential direction of the rotor. and a first core portion (C1) which is part of said rotor core. The rotor according to any one of claims 1 to 5,
The second magnet is divided into a first portion (122a) and a second portion (122b) that are adjacent to each other along the circumferential direction of the rotor. and a second core portion (C2) which is part of said rotor core. A rotor according to claim 6 depending on claim 5,
A rotor, wherein the dimension (W2) of the second core portion along the circumferential direction of the rotor is greater than the dimension (W1) of the first core portion along the circumferential direction of the rotor. The rotor according to any one of claims 1 to 7,
In the common core portion, the dimension (L1) of the common core portion corresponding to the distance between the first magnet and the second magnet corresponds to the distance between the third magnet and the fourth magnet. a rotor greater than the dimension (L2) of said common core portion that

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