WO2014030547A1

WO2014030547A1 - Rotor structure and rotor manufacturing method for permanent magnet type rotating electrical machine

Info

Publication number: WO2014030547A1
Application number: PCT/JP2013/071457
Authority: WO
Inventors: 浩平室田; 徹仲田
Original assignee: 日産自動車株式会社
Priority date: 2012-08-21
Filing date: 2013-08-08
Publication date: 2014-02-27

Abstract

A rotor core is arranged inside a stator and has a center axis and rotor slots inside the rotor core parallel to the center axis. A permanent magnet composite body with notches is constructed by adjacently arranging a plurality of permanent magnet pieces inside a respective rotor slot. The permanent magnet composite body inside the rotor slot has a first surface and a second surface that is positioned further away from the stator than the first surface. The notch is arranged on the second surface to prevent a degradation in resistance to demagnetization which is due to the notch.

Description

Rotor structure of permanent magnet type rotating electrical machine and rotor manufacturing method

The present invention relates to a rotor structure using a permanent magnet for a rotating electrical machine such as a motor or a generator and a manufacturing method thereof.

As an electric vehicle motor, an embedded magnet type (IPM) motor in which a permanent magnet is embedded in a rotor slot formed in a rotor is known.

JP2009-142081A, issued by the Japan Patent Office or in 2009, cleaves a permanent magnet formed by pressure-molding magnetic powder to generate a plurality of split pieces for a permanent magnet inserted into the rotor slot of such an IPM motor. It has been proposed to obtain an eddy current suppression effect by restoring the permanent magnet by inserting the piece into the rotor slot in an adjacent state.

In this case, the coercive force required for the permanent magnet is large on the stator side, that is, on the portion close to the supply side of the external magnetic field. This is because the coercive force necessary for the permanent magnet is determined by the magnitude of the external magnetic field input to the magnet. As a result, the required coercive force of the permanent magnet is increased on the stator side, which is the source of the external magnetic field.

In the prior art, in order to break and divide a permanent magnet, a notch is formed in advance by cutting or the like at the cleaved portion. When the cleaving machine applies pressure to the permanent magnet, the permanent magnet breaks from the notch and becomes a broken piece. Regardless of the formation method of the notch, it is inevitable that the magnetic force and the coercive force are lower than those of other portions due to the destruction of the surface structure. That is, the notch is a factor that impairs the anti-demagnetization performance of the rotor.

The present invention has been made to solve the above problems, and an object thereof is to improve the anti-demagnetization performance of a rotor using a split piece permanent magnet of an IPM motor.

According to an aspect of the present invention, a rotor structure of a permanent magnet type rotating electrical machine includes a rotor core that is disposed inside a stator and includes a central axis and a rotor slot that is formed substantially parallel to the central axis. And a permanent magnet composite having a notch, which is composed of a plurality of permanent magnet pieces arranged adjacent to each other.

The permanent magnet composite in the rotor slot has a first surface and a second surface far from the first surface with respect to the stator, and the permanent magnet composite has a notch located on the second surface. Located in the rotor slot.

FIG. 1 is a perspective view of a rotor core and permanent magnet composite according to an embodiment of the present invention. FIG. 2 is a diagram illustrating stress concentration on the burr due to centrifugal force. FIG. 3 is a diagram for explaining the relationship between the direction of the magnetic flux from the stator and the direction of the notch. FIG. 4 is a cross-sectional view of the rotor core for explaining a variation regarding the arrangement of the magnets on the rotor core. FIG. 5 is a cross-sectional view of the split piece showing variations relating to the transverse shape of the split piece. FIG. 6 is a perspective view of a rotor core and a permanent magnet composite for explaining variations regarding the forming direction of the notch. FIG. 7 is a perspective view of a rotor core and a permanent magnet composite for explaining another variation regarding the forming direction of the notch.

Referring to FIG. 1, the rotor 1 of the IPM motor has four rotor slots 4 inside a rotor core 5. The rotor core 5 has an annular cross section centered on the central axis O. Four rotor slots 4 surround the central axis O and are formed at intervals of 90 degrees. Each rotor slot 4 is parallel to the central axis O. That is, each rotor slot 4 extends in the longitudinal direction.

A plurality of split pieces 2 of permanent magnets are inserted into each rotor slot 4.

In the same way as in the prior art, the split piece 2 is produced by pressing a magnetic powder to produce a permanent magnet, forming a notch 3 in the permanent magnet, and then cutting the permanent magnet from the notch 3 with a cleaving device. Generated. The notch 3 is formed by melting a predetermined portion of the notch 3 of the permanent magnet by heating. Specifically, the notch 3 is formed by irradiating a laser at a predetermined position of the notch 3 of the permanent magnet.

The split pieces 2 generated in this way are sequentially inserted into the rotor slots 4 adjacent to each other in the axial direction in a state where the split cross section is orthogonal to the central axis O. At that time, the split piece 2 is inserted into the rotor slot 4 so that the notch 3 is positioned far from the stator in the rotor slot 4, that is, the notch 3 faces the central axis O.

The permanent magnet composite 20 configured in the rotor slot 4 in this way has a first surface 20A close to the stator and a second surface 20B located farther from the first surface 20A with respect to the stator. The split piece 2 is inserted into the rotor slot 4 so that the notch 3 is positioned on the second surface 20B.

Each rotor slot 4 is embedded with a permanent magnet composite 20 configured as described above. Alternatively, the permanent magnet composite 20 may be formed by laminating and adhering the magnet pieces 2 outside the rotor slot 4 in advance, and the formed permanent magnet composite 20 may be inserted into the rotor slot 4.

A hole in the longitudinal direction is formed in the center of the rotor core 5 in advance. The rotor core 5 is fixed to a rotating shaft (not shown) that passes through the hole. A stator (not shown) is disposed so as to surround the outer periphery of the rotor core 5.

The rotor core 1 configured as described above is rotated by the magnetic force exerted on the permanent magnet composite 20 composed of the split pieces 2 embedded in the four rotor slots 4 by the magnetic field formed by the stator during operation of the IPM motor. .

All of the plurality of split pieces 2 constituting the permanent magnet composite in the four rotor slots 4 are arranged with the notch portions 3 directed toward the central axis O on the opposite side of the stator. That is, since the notch 3 does not face the stator, the rotor 1 has a structure in which the resistance to demagnetization is not easily lowered by the notch 3. This will be specifically described below.

Referring to FIG. 3A, when the cutout portion 3 is formed by local melting of the split piece 2 by laser irradiation, a heat-affected zone due to heating is generated along with the coercive force reduction portion caused by the formation of the cutout portion 3 itself. The The heat-affected zone is a layer in which so-called irreversible demagnetization occurs in which the magnetic properties change due to the heat energy generated by laser irradiation and the magnetic force before irradiation does not return even after the temperature is lowered. The heat-affected zone is formed over a wider area than the coercive force drop zone. When the notch 3 is disposed in the rotor slot 4 toward the stator, that is, when the notch 3 is formed on the first surface 20A, the rotor 1 causes the coercive force lowering portion and the heat affected layer to face the magnetic flux from the stator. In other words, a decrease in anti-demagnetization performance is inevitable.

Referring to FIG. 3B, in this rotor 1, the notch portion 3 faces the central axis O by disposing the notch portion 3 at a position away from the stator in the rotor slot 4, that is, on the second surface 20 </ b> B. As a result, the permanent magnet composite 20 composed of a plurality of adjacent split pieces 2 is in a state in which the coercive force lowering portion and the heat-affected layer are directed to the opposite side with respect to the stator. Therefore, although the rotor 1 has the notch portion 3, it is difficult to be affected by the coercive force lowering portion and the heat-affected layer with respect to the magnetic flux from the stator, and high demagnetization resistance can be maintained.

When forming the cutout portion 3 in the permanent magnet, the cutout portion 3 is formed using thermal energy, in particular, by forming the cutout portion 3 by laser irradiation, it is easy to form the cutout portion 3 in the permanent magnet. Can be done. On the other hand, such a method for forming the notch 3 inevitably generates a heat-affected layer. The disposition of the notch 3 at a position far from the stator in the rotor slot 4, that is, the second surface, is remarkable with respect to the permanent magnet composite in which the notch 3 is formed by laser irradiation or the like where formation of a heat-affected layer is unavoidable It brings about an effect.

On the other hand, the coercive force required for the rotational operation of the IPM motor is smaller on the inner side of the rotor core 5 than on the outer side of the rotor core 5 facing the stator. Therefore, by arranging the coercive force lowering portion and the heat-affected layer toward the inner side of the rotor core 5, an optimal magnet arrangement in accordance with the required coercive force is realized.

Also, burrs may occur on both sides of the notch 3 when the notch 3 is generated. Referring to FIG. 2A, when the notch 3 is arranged on the first surface 20 </ b> A on the stator side, the centrifugal force accompanying the rotation of the IPM motor increases the contact pressure between the burr and the wall surface of the rotor slot 4. As a result, the compressive stress generated in the burr increases with the length of the split piece 2 in the adjacent direction as shown in FIG. In order to prevent damage to the member due to stress concentration, it is necessary to sufficiently remove the burrs, but there are cases where the burrs cannot be completely removed.

In the rotor 1 according to the present invention, the notch 3 is arranged on the second surface 20B corresponding to a position away from the stator in the rotor slot 4 in advance, so that the notch 3 is directed to the central axis O. Therefore, the centrifugal force accompanying the rotation of the IPM motor acts on the split piece 2 in the direction of reducing the contact pressure between the burr and the wall surface of the rotor slot 4. Therefore, even if burrs remain around the notch 3 of the split piece 2, the load due to the centrifugal force does not concentrate on the burrs when the IPM motor rotates.

Referring to FIG. 4, another embodiment of the present invention relating to the arrangement of magnets on the rotor core 5 will be described.

In the embodiment of FIG. 1, four rotor slots 4 are formed in the rotor core 5 at intervals of 90 degrees, but the position and quantity of the rotor slots 4 are not limited to this.

In FIG. 4A, a slot group composed of three rotor slots 4 arranged so as to form a substantially triangular shape is arranged at intervals of 90 degrees. Each rotor slot 4 is embedded with the same split piece 2 as in the embodiment of FIG. 1 to constitute a permanent magnet composite 20. In this embodiment, the direction of the notch 3 is set as follows.

That is, with respect to the permanent magnet composite 20 embedded in the rotor slot 4 from the outermost periphery of the rotor core 5 in each slot group, the notch 3 is disposed on the second surface 20B corresponding to a position far from the stator. With respect to the split piece 2 embedded in the other rotor slot 4, any orientation of the notch 3 is possible. However, by arranging the notch 3 on the second surface 20B corresponding to a position far from the stator for these rotor slots 4 as well, a more favorable effect can be obtained with respect to maintaining the demagnetization resistance performance of the rotor 1.

FIG. 4B corresponds to a configuration in which the rotor slot 4 from the outermost periphery of each slot group is omitted from the magnet arrangement of FIG. 4A.

Also in this embodiment, the split piece 2 embedded in each rotor slot 4 is arranged so that the notch 3 comes to the second surface 20B far from the stator of the rotor slot 4.

FIG. 4C corresponds to a structure in which a smaller rotor slot 4 is formed in parallel outside the rotor slot 4 of the embodiment of FIG. In this embodiment, the notch 3 of the split piece 2 of the permanent magnet embedded in the outer rotor slot 4 is provided on the second surface 20B facing the central axis O. With respect to the split piece 2 of the permanent magnet embedded in the inner rotor slot 4, any orientation of the notch 3 is possible. However, by arranging the split piece 2 in the rotor slot 4 so that the notch 3 comes to the second surface 20B far from the stator in the inner rotor slot 4, in other words, the central axis O of the permanent magnet complex By providing the notch 3 on the surface facing, a more favorable effect can be obtained with respect to maintaining the anti-demagnetization performance of the rotor 1.

In the embodiment of FIG. 1, the shape of the transverse section of the split piece 2 cut in parallel with the split section is a rectangle. However, the cross-sectional shape of the split piece 2 is not limited to a rectangle. Various cross-sectional shapes such as a trapezoid shown in FIG. 5A and a kamaboko shape shown in FIG. 5B can be adopted.

In the embodiment of FIG. 1, the notch 3 is formed in a direction orthogonal to the central axis O. However, the rotor structure and the rotor manufacturing method according to the present invention are not limited to the direction in which the notch 3 is formed.

As shown in FIG. 6, it is possible to set the direction of the notch 3 parallel to the central axis O. Further, as shown in FIG. 7, the direction of the notch 3 can be set obliquely with respect to the central axis O.

In each of the above embodiments, the notch 3 is formed by laser irradiation, and a heat affected zone is formed in the notch 3 in addition to the coercive force lowering portion. In this way, the present invention exerts a remarkable effect in preventing the demagnetization resistance of the rotor having the notched portion 3 in which the heat affected zone is formed in addition to the coercive force lowered portion. However, even when the present invention is applied to a rotor in which a notch portion is formed by cutting or the like, a favorable effect can be obtained in preventing a decrease in the anti-demagnetization performance of the rotor caused by the coercive force reduction portion.

The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

This application claims priority based on Japanese Patent Application No. 2012-182715 filed with the Japan Patent Office on August 21, 2012, the entire contents of which are incorporated herein by reference.

Claims

In the rotor structure of a permanent magnet type rotating electrical machine, which is disposed inside the stator and has a central axis and a rotor slot formed in parallel with the central axis,
A rotor core having a central axis and a rotor slot formed in parallel with the central axis, disposed inside the stator;
A permanent magnet composite composed of a plurality of permanent magnet pieces arranged adjacent to the rotor slot,
The permanent magnet composite in the rotor slot has a first surface, a second surface farther from the stator than the first surface, and a rotor structure of a permanent magnet type rotating electrical machine having a notch portion present on the second surface. .
The rotor structure of the permanent magnet type rotating electric machine according to claim 1, wherein the notch is arranged toward the central axis.
The rotor structure of a permanent magnet type rotating electric machine according to claim 1 or 2, wherein the plurality of permanent magnet pieces are generated by cleaving a permanent magnet having a notch portion formed beforehand at the notch portion.
In a method of manufacturing a rotor of a permanent magnet type rotating electrical machine, which is disposed inside a stator and has a central axis and a rotor slot formed in parallel with the central axis,
By arranging a plurality of permanent magnet pieces adjacent to each other in the rotor slot, the permanent magnet has a first surface, a second surface farther from the stator than the first surface, and a notch portion present on the second surface. A method for manufacturing a rotor of a permanent magnet type rotating electrical machine, wherein a magnet composite is formed in a rotor slot.
The method for manufacturing a rotor of a permanent magnet type rotating electrical machine according to claim 4, wherein the plurality of permanent magnet pieces are arranged adjacent to each other in the rotor slot so that the notch portion faces the central axis.
The method for manufacturing a rotor of a permanent magnet type rotating electric machine according to claim 4, wherein a plurality of permanent magnet pieces are generated by cleaving a permanent magnet having a notch formed in advance at the notch.
The method for manufacturing a rotor of a permanent magnet type rotating electric machine according to claim 6, wherein the notch is formed by using thermal energy.
The rotor manufacturing method for a permanent magnet type rotating electrical machine according to claim 6, wherein the notch is formed by laser irradiation.