WO2020166574A1

WO2020166574A1 - Embedded-magnet-type rotor

Info

Publication number: WO2020166574A1
Application number: PCT/JP2020/005206
Authority: WO
Inventors: 駿竹内; 勝也藤崎
Original assignee: 株式会社デンソー
Priority date: 2019-02-15
Filing date: 2020-02-11
Publication date: 2020-08-20
Also published as: JP7024745B2; JP2020137208A

Abstract

In the present invention, a rotor core (23) has: an inside magnetic part (26) located on the radially inner side relative to a magnet insertion hole (24); a salient pole part (27) located on the radially outer side relative to the magnet insertion hole (24), the salient pole part (27) being formed so as to diverge radially inwards from the circumscribed circle of the rotor core (23) commensurately with increasing circumferential-direction distance from the magnetic pole center; and bridge parts (28) extending towards the inside-magnetic-part (26) side from both circumferential sides of the salient pole part (27). A permanent magnet (25) is in contact with the inside magnetic part (26) and is not in contact with the salient pole part (27). A circumferential-direction gap (31) is formed on both circumferential sides of the permanent magnet (25) so that the radially outer side of the permanent magnet (25) and the bridge parts (28) are not in contact. An elastic member (32) is installed in at least one of the circumferential-direction gaps (31) on the two sides of the permanent magnet (25). The elastic member (32) urges the permanent magnet (25) in the circumferential direction and secures the permanent magnet (25).

Description

Embedded magnet type rotor

Cross-reference of related applications

This application is based on the patent application No. 2019-25804 filed on February 15, 2019, and the contents of the description are incorporated herein.

The present disclosure relates to an embedded magnet type rotor.

Conventionally, an embedded magnet type rotor is known in which a permanent magnet is provided in the magnet insertion hole of the rotor core, and the permanent magnet is pressed by an elastic member against the wall surface on the radially outer side of the magnet insertion hole to be fixed. In Patent Document 1, an elastic material insertion groove is provided at a radially inner corner portion of the magnet insertion hole, and the permanent magnet is urged radially outward by the elastic material inserted into the elastic material insertion groove.

Patent No. 2000-341920

In Patent Document 1, the permanent magnet is pressed against the wall surface on the radially outer side of the magnet insertion hole with an elastic material to be fixed, whereby the permanent magnet moves in the circumferential direction at the start of rotation of the embedded magnet type rotor, and The generation of abnormal noise due to collision with the wall surface is suppressed.

However, when the magnet fixing method as described above is adopted in the rotor core in which the bridge portions are formed on both sides in the circumferential direction of the salient pole portion, in addition to the pressing force by the elastic material, the magnetic force or centrifugal force of the permanent magnet is applied to the salient pole portion. It works strongly. Therefore, there is a problem that a load is applied to the bridge portion and it is difficult to achieve high rotation.

The present disclosure has been made in view of the above points, and an object thereof is to provide an embedded magnet type rotor capable of reducing the load applied to the bridge portion while suppressing abnormal noise at the start of rotation. ..

An embedded magnet rotor of the present disclosure includes a rotor core having a magnet insertion hole, a permanent magnet provided in the magnet insertion hole, having a rectangular cross section, and having a thickness direction extending along a radial direction of the rotor core. And an elastic member that is provided in the magnet insertion hole and presses the permanent magnet against the wall surface of the magnet insertion hole.

The rotor core is located radially inward of the magnet insertion hole, and radially outward of the magnet insertion hole. The rotor core is radially inward from the circumscribed circle of the rotor core as the magnetic pole center is circumferentially separated. It has a salient pole portion formed so as to be separated from each other, and a bridge portion extending from both sides in the circumferential direction of the salient pole portion to the inner magnetic portion side. The permanent magnet is in contact with the inner magnetic portion and is not in contact with the salient pole portion. Circumferential gaps are formed on both sides of the permanent magnet in the circumferential direction so that the radial outside of the permanent magnet and the bridge portion are not in contact with each other. The elastic member is disposed in at least one of the two circumferential gaps on both sides of the permanent magnet, and biases and fixes the permanent magnet in the circumferential direction.

Due to this, the permanent magnet is magnetically stable in the inner magnetic part (that is, the side where the magnetic resistance is smaller), so the radial fixing force of the permanent magnet is not required so much. Further, since there is a gap between the permanent magnet and the salient pole portion, the magnetic force and centrifugal force of the permanent magnet acting on the salient pole portion can be suppressed. Therefore, the load applied to the bridge portion can be reduced, and the rotation speed can be easily increased.

Also, since there is a gap between the permanent magnet and the magnet insertion hole in the radial direction, the insertability of the permanent magnet into the magnet insertion hole is good. Further, since the permanent magnet is arranged inside the magnet insertion hole in the radial direction, the inertia of the embedded magnet type rotor can be reduced. Further, since the permanent magnets are fixed in the circumferential direction by the elastic member, generation of abnormal noise at the start of rotation of the embedded magnet type rotor is suppressed. Further, by providing the salient pole portions on the magnetic poles, the torque ripple and the induced voltage distortion generated by the rotor core can be reduced. Further, by providing the bridge portions on both sides in the circumferential direction of the salient pole portion, it is possible to suppress the short-circuit magnetic flux between the adjacent magnetic poles and increase the torque. Further, by making the cross-sectional shape of the permanent magnet a simple shape such as a rectangle, the processing cost of the permanent magnet can be suppressed.

The above and other objects, features and advantages of the present disclosure will become more apparent by the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is a sectional view of a rotary electric machine to which an embedded magnet type rotor according to the first embodiment is applied, 2 is a front view of the embedded magnet rotor of FIG. FIG. 3 is an enlarged view of part III of FIG. 4 is a sectional view taken along line IV-IV of FIG. FIG. 5 is a partially enlarged view of the embedded magnet type rotor according to the second embodiment and is a view corresponding to FIG. 3 of the first embodiment.

A plurality of embodiments of the embedded magnet type rotor will be described below with reference to the drawings. The configurations that are substantially the same between the embodiments are given the same reference numerals, and description thereof will be omitted.

[First Embodiment]
The embedded magnet type rotor (hereinafter, rotor) according to the first embodiment is applied to the rotary electric machine 10 shown in FIG. 1. The rotary electric machine 10 includes a housing 11, a motor shaft 12, a stator 13, and a rotor 14.

The motor shaft 12 is rotatably supported by the housing 11 via a bearing 15. The stator 13 has a stator core 21 fixed to the housing 11 and a winding wire 22 assembled to the stator core 21.

As shown in FIGS. 1 and 2, the rotor 14 is made of a magnetic material, and has a rotor core 23 fitted and fixed to the motor shaft 12, and a plurality of permanent magnets provided in magnet insertion holes 24 of the rotor core 23. 25 and.

Hereinafter, the radial direction of the rotor 14 will be simply referred to as “radial direction”, and the circumferential direction (that is, the rotational direction) of the rotor 14 will be simply referred to as “circumferential direction” or “rotational direction”. The direction is simply referred to as an “axial direction”, and the cross section of the rotor 14 is simply referred to as a “cross section”.

As shown in FIG. 3, the rotor core 23 is located radially inside the magnet insertion hole 24, and radially outside the magnet insertion hole 24. The rotor core 23 has a salient pole portion 27 formed to be radially inward from the circumscribed circle of the rotor core 23, and a bridge portion 28 extending from both circumferential sides of the salient pole portion 27 toward the inner magnetic portion 26. ing. The radius of curvature of the salient pole portion 27 is smaller than the radius of curvature of the circumscribed circle. The permanent magnet 25 has a rectangular cross section and is arranged so that the thickness direction thereof is along the radial direction.

The rotor 14 is magnetically attracted or repelled by a rotating magnetic field generated by energization of the winding wire 22 to rotate. When the rotor 14 starts rotating in this manner, the electromagnetic force in the circumferential direction from the stator 13 acts on the permanent magnet 25. At this time, if the permanent magnet 25 is not fixed to the rotor core 23, the permanent magnet 25 moves in the circumferential direction within the magnet insertion hole 24, collides with the wall surface of the magnet insertion hole 24, and abnormal noise is generated.

In the past, in order to prevent the occurrence of abnormal noise as described above, a permanent magnet was conventionally pressed against an outer wall surface of the magnet insertion hole in the radial direction by an elastic material and fixed. However, when the conventional magnet fixing method is adopted in the rotor core 23 forming the bridge portions 28 on both sides in the circumferential direction of the salient pole portion 27, in addition to the pressing force by the elastic material, the magnetic force and the centrifugal force of the permanent magnet 25 are generated. It strongly acts on the salient pole portion 27. Therefore, a load is applied to the bridge portion 28, and it becomes difficult to achieve high rotation.

On the other hand, in the first embodiment, as shown in FIG. 3, the permanent magnet 25 is in contact with the inner magnetic portion 26 and is not in contact with the salient pole portion 27. Circumferential gaps 31 are formed on both sides of the permanent magnet 25 in the circumferential direction so that the radially outer side of the permanent magnet 25 and the bridge portion 28 are not in contact with each other. An elastic member 32 is arranged in one of the two circumferential gaps 31 on both sides of the permanent magnet 25. The elastic member 32 biases and fixes the permanent magnet 25 in the circumferential direction.

In the first embodiment, the permanent magnet 25 is pressed against the protrusion 33 formed on the wall portion of the magnet insertion hole 24. The protrusion 33 is formed so as to protrude from the radially inner portion of the wall portions on both sides in the rotation direction that define the magnet insertion hole 24 toward the permanent magnet 25 side. The tip surface 34 of the protrusion 33 is flat.

The rotor core 23 is a laminated body made of a plurality of electromagnetic steel plates (not shown). 2 and 4, the rotor core 23 is illustrated as one member in order to avoid complication. Returning to FIG. 3, the bridge portion 28 has a circumferential bridge portion 35 extending in the circumferential direction from the salient pole portion 27 and a radial bridge portion 36 extending inward in the radial direction from the circumferential bridge portion 35. doing. When the thickness of the electromagnetic steel sheet is t [mm], the width of the circumferential bridge portion 35 is x [mm], and the width of the radial bridge portion 36 is w [mm], the relationship of the expression (1) is established.
0.3<x<t=w<2 (1)

The permanent magnet 25 is magnetically stable in the inner magnetic portion 26 (that is, the side having a smaller magnetic resistance) on the radially inner side of the magnet insertion hole 24. As a result, a gap (hereinafter referred to as a radially outward gap 37) is formed between the salient pole portion 27 and the permanent magnet 25. The magnet insertion hole 24 includes a void 38 that connects the circumferential void 31 and the radially outward void 37. The void 38 is a relief portion for avoiding interference with the corner portion of the permanent magnet 25.

The corner portion 41 between the circumferential bridge portion 28 and the salient pole portion 27, the inside of the circumferential bridge portion 35, and the corner portion 42 between the circumferential bridge portion 35 and the radial bridge portion 36 have a round shape. The round shape is a shape whose cross-sectional shape is a concave curve. When the radius of curvature of the corner portion 41 is R [mm], the relationship of Expression (2) is established.
0.15<R<0.4...(2)

As shown in FIGS. 3 and 4, the elastic member 32 is a spring pin made of a non-ferrous metal such as stainless steel or a non-magnetic material such as resin. The elastic member 32 has a tapered end portion in the axial direction. The axial length of the elastic member 32 is ⅓ or more of the axial length of the permanent magnet 25.

(effect)
As described above, in the first embodiment, the embedded magnet type rotor 14 is provided in the rotor core 25 having the magnet insertion hole 26 and the magnet insertion hole 24, has a rectangular cross section, and has a rotor core in the thickness direction. The permanent magnet 27 is arranged along the radial direction of 23, and the elastic member 32 is provided in the magnet insertion hole 24 and presses the permanent magnet 25 against the wall surface of the magnet insertion hole 24.

The rotor core 23 is located radially inward of the magnet insertion hole 24, and radially outward of the magnet insertion hole 24. The rotor core 23 is circumscribed from the magnetic pole center in the circumferential direction. It has a salient pole portion 27 formed so as to be separated inward in the radial direction, and a bridge portion 28 extending from both circumferential sides of the salient pole portion 27 toward the inner magnetic portion 26. The permanent magnet 25 is in contact with the inner magnetic portion 26 and is not in contact with the salient pole portion 27. Circumferential gaps 31 are formed on both sides of the permanent magnet 25 in the circumferential direction so that the radially outer side of the permanent magnet 25 and the bridge portion 28 are not in contact with each other. The elastic member 32 is arranged in at least one of the two circumferential gaps 31 on both sides of the permanent magnet 25, and biases and fixes the permanent magnet 25 in the circumferential direction.

Due to this, the permanent magnet 25 is magnetically stabilized at the inner magnetic portion 26 (that is, the side on which the magnetic resistance is smaller), so the radial fixing force of the permanent magnet 25 is not required so much. Further, since there is the radially outer gap 37 between the permanent magnet 25 and the salient pole portion 27, the magnetic force or centrifugal force of the permanent magnet 25 acting on the salient pole portion 27 can be suppressed. Therefore, the load applied to the bridge portion 28 can be reduced, and the rotation speed can be easily increased.

Moreover, since there is a gap between the permanent magnet 25 and the magnet insertion hole 24 in the radial direction, the insertability of the permanent magnet 25 into the magnet insertion hole 24 is good. Further, since the permanent magnet 25 is arranged inside the magnet insertion hole 24 in the radial direction, the inertia of the embedded magnet type rotor 14 can be reduced. Further, since the permanent magnets 25 are fixed in the circumferential direction by the elastic member 32, generation of abnormal noise at the start of rotation of the embedded magnet type rotor 14 is suppressed. Further, by providing the salient pole portion 27 on the magnetic pole, it is possible to reduce torque ripple and induced voltage distortion generated by the rotor core 23. Further, by providing the bridge portions 28 on both sides of the salient pole portion 27 in the circumferential direction, it is possible to suppress short-circuit magnetic flux between adjacent magnetic poles and increase torque. Further, by making the cross-sectional shape of the permanent magnet 25 a simple shape such as a rectangle, the processing cost of the permanent magnet 25 can be suppressed.

Further, in the first embodiment, the rotor core 23 is a laminated body made of a plurality of electromagnetic steel plates. The bridge portion 28 has a circumferential bridge portion 35 extending in the circumferential direction from the salient pole portion 27, and a radial bridge portion 36 extending inward in the radial direction from the circumferential bridge portion 35. The circumferential bridge portion 35 and the radial bridge portion 36 are formed so as to satisfy the relationship of the above expression (1). Since the width x is smaller than the thickness t and the width w in this way, the short-circuit magnetic flux path is narrowed, so that the motor torque can be improved.

In addition, in the first embodiment, the magnet insertion hole 24 includes a void 38 that connects the circumferential void portion 31 and the radially outward void 37. This makes it possible to avoid contact between the corners of the permanent magnet 25 and the rotor core 23. Therefore, even if the corners of the permanent magnet 25 are sharp, it is possible to prevent chipping during insertion. Therefore, it is not necessary to process the corners of the permanent magnet 25 into a round shape, and the processing cost of the permanent magnet 25 can be suppressed.

Further, in the first embodiment, the radius of curvature R of the corner 41 between the circumferential bridge portion 35 and the salient pole portion 27 satisfies the relationship of the above expression (2). By setting the dimensions in this way, it becomes easy to insert the permanent magnet 25 into the magnet insertion hole 24.

Also, in the first embodiment, the elastic member 32 is a spring pin made of a non-magnetic material. As a result, the permanent magnet 25 can be fixed without being affected by the magnetic force. Further, the elastic member 32 has a tapered end portion in the axial direction. As a result, the elastic member 32 is easy to press fit.

[Second Embodiment]
In the second embodiment, as shown in FIG. 5, the elastic members 32 are arranged in both of the two circumferential gaps 31 on both sides of the permanent magnet 25. As a result, the permanent magnet 25 can be arranged at the center of the magnetic pole, and the magnetic difference between the left and right with respect to the center of the magnetic pole can be eliminated.

[Other Embodiments]
In another embodiment, the elastic member is not limited to the spring pin, and may be a spring having another shape or an elastic body such as rubber. Further, a plurality of elastic members may be provided in the axial direction.

The present disclosure has been described based on the embodiments. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also includes various modifications and modifications within an equivalent range. Further, various combinations and forms, and other combinations and forms including only one element, more, or less than those are also within the scope and spirit of the present disclosure.

Claims

A rotor core (23) having a magnet insertion hole (24);
A permanent magnet (25) provided in the magnet insertion hole, having a rectangular cross section, and having a thickness direction extending along the radial direction of the rotor core;
An elastic member (32) provided in the magnet insertion hole and pressing the permanent magnet against the wall surface of the magnet insertion hole;
Equipped with
The rotor core is located on the inner side in the radial direction with respect to the magnet insertion hole, and is located on the outer side in the radial direction with respect to the magnet insertion hole. A salient pole portion (27) formed so as to separate from the circumscribed circle inward in the radial direction; ,
The permanent magnet is in contact with the inner magnetic portion and is not in contact with the salient pole portion,
Circumferential gaps (31) are formed on both sides of the permanent magnet in the circumferential direction so that the radially outer side of the permanent magnet and the bridge portion are not in contact with each other.
The embedded magnet type rotor, wherein the elastic member is disposed in at least one of the two circumferential gaps on both sides of the permanent magnet, and biases and fixes the permanent magnet in the circumferential direction.
The rotor core is a laminated body made of a plurality of electromagnetic steel plates,
The bridge portion includes a circumferential bridge portion (35) extending in the circumferential direction from the salient pole portion, and a radial bridge portion (36) extending inward in the radial direction from the circumferential bridge portion,
When the thickness of the electromagnetic steel plate is t [mm], the width of the circumferential bridge portion is x [mm], and the width of the radial bridge portion is w [mm],
0.3<x<t=w<2
2. The embedded magnet type rotor according to claim 1.
When the gap between the salient pole portion and the permanent magnet is a radial gap (37),
The embedded magnet type rotor according to claim 2, wherein the magnet insertion hole includes a space (38) connecting the circumferential space and the radially outer space.
When the radius of curvature of the corner portion (41) between the circumferential bridge portion and the salient pole portion is R [mm],
0.15<R<0.4
The embedded magnet type rotor according to claim 2 or 3.
The embedded magnet type rotor according to any one of claims 1 to 4, wherein the elastic member is a spring pin made of a non-magnetic material.
The embedded magnet rotor according to any one of claims 1 to 5, wherein the elastic member is arranged in both of the two circumferential gaps on both sides of the permanent magnet.