JPH09275651A - Permanent magnet rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a high-energy magnet as a permanent magnet to be mounted on a rotor. SOLUTION: This permanent magnet rotary machine has a rotor 1 which is made by mounting permanent magnets 3 on a shaft 2. In this case, the permanent magnet 3 consists of a high-energy magnet 5 located on the inner side and a heat-resisting magnet 6 located on the outer side. Due to this structure of the permanent magnet 3, when a holding ring 4 is fit by heat treatment only the heat-resisting magnet 6 is brought into direct contact with the holding ring 4 and the high-energy magnet 5 is not brought into contact with the holding ring 4 of a high temperature. Therefore, the high-energy magnet 5 is not demagnetized at the time of fit by heat treatment and so, a high-energy magnet can be used as a permanent magnet in this rotary machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet rotating electric machine including a rotor configured by attaching a permanent magnet to a shaft.

[0002]

2. Description of the Related Art For example, a permanent magnet motor is constructed such that a permanent magnet is attached to a shaft of a rotor and a cylindrical holding ring is fitted and fixed to the outer circumference of the permanent magnet. In this configuration, when the rotor rotates at high speed and a strong centrifugal force acts on the permanent magnet, the retaining ring prevents the permanent magnet from coming off the rotor.

[0003]

In the above structure, the retaining ring is fitted and fixed to the outer circumference of the permanent magnet by so-called shrink fitting. When this shrink fitting is performed, since the holding ring is heated to a high temperature state and then fitted to the outer circumference of the permanent magnet, heat is transmitted from the holding ring to the permanent magnet, and the temperature of the permanent magnet becomes considerably high. On the other hand, a permanent magnet generally has a property of decreasing magnetic energy and generated magnetic flux density, that is, a property of demagnetizing at high temperature. In this case, once demagnetized, it is divided into a magnet part that does not return to the original characteristics (irreversible demagnetization) and a magnet part that returns (reversible demagnetization) even if the temperature drops. In the step of shrink-fitting the retaining ring (because the rotor surface is exposed to the air), there is a tendency that many magnet portions that do not return are increased. Further, as shown in FIG. 10, a high-energy magnet, which is a permanent magnet having high magnetic energy and generated magnetic flux density, has poor temperature characteristics and has a characteristic of being rapidly demagnetized at high temperatures. 10 is a characteristic diagram showing the temperature dependence of the magnetization curve of the high energy magnet.

On the other hand, a permanent magnet having good temperature characteristics and being not so demagnetized even at high temperatures,
That is, a heat resistant magnet has been developed (see FIG. 11). However, if the temperature characteristics are improved, there is a problem that the magnetic energy and the generated magnetic flux density become low. On the other hand, in order to increase the output of the permanent magnet motor, it is necessary to use a permanent magnet having high magnetic energy and generated magnetic flux density. However, in practice, since the work of attaching the retaining ring by shrink fitting has to be performed, a heat-resistant magnet having low magnetic energy and generated magnetic flux density has to be used as the permanent magnet.

Therefore, an object of the present invention is to provide a permanent magnet rotating electric machine in which a high energy magnet can be used as a permanent magnet.

[0006]

A permanent magnet rotating electric machine according to the present invention is a permanent magnet rotating electric machine comprising a rotor having a shaft to which a permanent magnet is attached. It is characterized in that it is composed of an energy magnet and a heat-resistant magnet arranged outside.

According to the above construction, since the high energy magnet is arranged inside and the heat resistant magnet is arranged outside, only the heat resistant magnet becomes the high temperature holding ring when the holding ring is shrink-fitted. In direct contact, the high energy magnet no longer contacts the hot retaining ring. Therefore, the high-energy magnet is not demagnetized during shrink fitting, so that the high-energy magnet can be used as the permanent magnet.

Further, in the case of the above construction, it is preferable to provide a vibration damping member between the high energy magnet and the heat resistant magnet. Further, it is preferable that the heat resistant magnet is divided into a plurality of pieces and a yoke block is provided between the divided heat resistant magnets. Furthermore, in a configuration in which a retaining ring made of a magnetic material is fitted to the outer periphery of the permanent magnet, it is a good configuration to provide yoke blocks at both ends in the circumferential direction of the heat resistant magnet.

On the other hand, in a permanent magnet rotating electric machine comprising a rotor constituted by attaching a permanent magnet to a shaft, the permanent magnet is mainly arranged inside a magnet composition component for a high-energy magnet and at the same time a heat-resistant magnet is used. The composite magnet is preferably produced by compression-molding both the magnet composition components by a molding die so that the magnet composition components are mainly arranged on the outside, and then sintering the molded product.

In the case of this construction, it is also a good construction to disperse small piece-shaped yoke blocks in the outer layer portion composed of the magnet composition component for the heat resistant magnet when the composite magnet is manufactured. Further, in a configuration in which a retaining ring made of a magnetic material is fitted to the outer periphery of a permanent magnet, yoke blocks are provided at both ends in the circumferential direction of the outer layer portion of at least the heat-resistant magnet of the composite magnet. It is preferable to provide.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment in which the present invention is applied to a permanent magnet motor will be described below with reference to FIGS. First, in FIG. 1 showing a rotor of a permanent magnet electric motor, the rotor 1 includes a shaft 2, a plurality of permanent magnets 3 attached to the outer periphery of the shaft 2, and an outer periphery of the permanent magnets 3 fitted as described below. And a holding ring 4 having a cylindrical shape that is joined together.

As shown in FIG. 2, each of the permanent magnets 3 is formed in a substantially semi-cylindrical shape as a whole, and
The high-energy magnet 5 arranged inside and the heat-resistant magnet 6 arranged outside are bonded, for example.
Here, the high-energy magnet 5 is composed of a neodymium magnet, for example, a neodymium magnet having a trade name “NEOMAX-37” manufactured and sold by Sumitomo Special Metals Co., Ltd. This neodymium magnet has an energy product (B ×
H) is a very high permanent magnet (that is, a permanent magnet having high magnetic energy and generated magnetic flux density).

The heat-resistant magnet 6 is a rare earth cobalt magnet, for example, a samarium cobalt magnet, or a trade name "NEOMAX-" manufactured and sold by Sumitomo Special Metals Co., Ltd.
28 UH ”neodymium magnet (this magnet is a neodymium magnet that has temperature dependence of the magnetization curve as shown in FIG. 11 and is not so demagnetized even at high temperatures). Has been done. Such a permanent magnet has a lower energy product than the high-energy magnet 5, but has a good temperature characteristic (that is,
It is a permanent magnet that retains high power even at high temperatures.

Then, when the retaining ring 4 is fitted and fixed to the outer periphery of the permanent magnet 3 attached to the shaft 2, shrink fitting is performed. In this case, specifically, the holding ring 4 is heated to a high temperature state (for example, about 100 ° C.) to expand its inner diameter, and then the holding ring 4 is fitted to the outer periphery of the permanent magnet 3, After that, the retaining ring 4 is cooled and its inner diameter is reduced, so that the retaining ring 4 is firmly fixed to the outer periphery of the permanent magnet 3. By firmly fixing in this manner, even if the rotor 1 rotates at a high speed and a strong centrifugal force acts on the permanent magnet 3, the retaining ring 4 prevents the permanent magnet 3 from coming off from the rotor 1 (the shaft 2 thereof). To be done.

When the retaining ring 4 is shrink-fitted, only the heat-resistant magnet 6 arranged on the outer side of the permanent magnet 3 is in direct contact with the high temperature retaining ring 4 and the high temperature magnet arranged on the inner side. The energy magnet 5 does not contact the hot retaining ring 4.
Therefore, since the high energy magnet 5 does not reach a high temperature during the shrink fitting work, the high energy magnet 5 is not demagnetized. Therefore, the high-energy magnet 5 can be used as the permanent magnet 3, and the output (rotational force) of the permanent magnet motor can be increased accordingly.

By the way, in the above embodiment, the high energy magnet 5 and the heat resistant magnet 6 are directly bonded. Therefore, a contact interface exists between the magnets 5 and 6, and the retaining ring 4 restrains the permanent magnet 3 due to a dimensional error between the magnets 5 and 6 and a difference in coefficient of thermal expansion. It became non-uniform, and rattling and gaps sometimes occurred. And
Since the material of the permanent magnet is generally a hard material, the permanent magnet is very brittle and has a property of being easily damaged by an impact. In addition, the electric motor is likely to be impacted during operation. Therefore, it is necessary to reduce the interface between the magnets 5 and 6 as much as possible.

On the other hand, a vibration-proof member, for example, a sheet made of a vibration-proof material is provided between the high-energy magnet 5 and the heat-resistant magnet 6, and more specifically, the both magnets 5 are interposed with the sheet interposed therebetween. A configuration in which 6 is bonded is conceivable. According to this structure, since there is no rattling or gap between the magnets 5 and 6, it is possible to prevent the magnets 5 and 6 from being damaged even if an impact occurs during operation.

On the other hand, when the high-energy magnet 5 and the heat-resistant magnet 6 are bonded as in the first embodiment, the magnetic flux generated from the high-energy magnet 5 has the performance (magnetic resistance, It may be limited by the maximum allowable magnetic flux density). In this case, a part of the magnetic flux generated from the high energy magnet 5 may become a leakage magnetic flux and may not reach the surface of the rotor 1. In this case, the operating magnetic flux density (that is, the gap magnetic flux density) of the two magnets 5,
Since the value becomes lower than the combined value of 6, there is a drawback that sufficient electric motor performance cannot be obtained.

In order to eliminate such drawbacks, it is preferable to construct the second embodiment of the present invention shown in FIG. The second embodiment will be described below by referring to differences from the first embodiment. The same parts as those of the first embodiment are denoted by the same reference numerals. In the second embodiment,
The heat-resistant magnet 5 of the permanent magnet 3 is divided into a plurality of pieces, and a yoke block 8 is provided between the divided heat-resistant magnets 7, whereby a part of the heat-resistant magnet 5 is replaced with the yoke block 8. ing. The above yoke block 8
Is formed of a material having a large saturation magnetic flux density such as iron or cobalt. The configuration of the second embodiment other than the above is the same as the configuration of the first embodiment.

Therefore, also in the second embodiment, the same operational effect as in the first embodiment can be obtained. Especially,
In the second embodiment, since the yoke block 8 is arranged between the split heat-resistant magnets 7, the magnetic flux generated from the high energy magnet 5 reaches the surface of the rotor 1 through the yoke block 8. , And contributes to the rotational force of the rotor 1. Therefore, the generated magnetic flux density of the high-energy magnet 5 is not attenuated, so that sufficient electric motor performance (output) can be obtained.

Further, in each of the above embodiments, the retaining ring 4
It is a preferable configuration to form the magnetic material.
According to this configuration, the gap is effectively reduced, so that large rotational energy can be obtained. However, in the case of the above configuration, since the retaining ring 4 has a ring shape (cylindrical shape), a part of the magnetic flux flows to the adjacent magnetic pole and becomes a leakage magnetic flux, and this magnetic flux may not contribute to the rotational force. .

In order to eliminate such a problem, FIG.
The third embodiment of the present invention shown in FIG. The third embodiment will be described below by referring to differences from the first embodiment. The same parts as those of the first embodiment are denoted by the same reference numerals. In the third embodiment described above, the retaining ring 4 made of a magnetic material is fitted and fixed to the outer periphery of the permanent magnet 3 by shrink fitting, and the bar rod-like yoke blocks 9 are provided at both ends of the heat resistant magnet 6 in the circumferential direction. It is configured to be arranged. In the case of this configuration, both end portions in the circumferential direction of the heat resistant magnet 6 are configured to be shorter than both end portions in the circumferential direction of the high energy magnet 4, and recessed portions are formed at both end portions of the heat resistant magnet 6 in the recessed portions. The yoke block 9 is housed and is fixed, for example, by adhesion. The yoke block 9 is made of a material having a large saturation magnetic flux density such as iron or cobalt.

The structure of the third embodiment other than the above is the same as the structure of the first embodiment. Therefore, also in the third embodiment, it is possible to obtain the same effect as that of the first embodiment. Particularly, in the third embodiment, since the yoke blocks 9 are arranged at both ends in the circumferential direction of the heat resistant magnet 6, it is generated from the high energy magnet 5 of the two layers of magnets 5 and 6. The surplus magnetic flux is made to demagnetize by flowing through the yoke block 9 to both ends of the magnetic pole portion of the retaining ring 4 and magnetically saturating the portions. This makes it possible to prevent leakage of the magnetic flux that contributes to the rotational force.

FIGS. 5 and 6 show a fourth embodiment of the present invention, and the difference from the third embodiment will be described. The same parts as those in the third embodiment are designated by the same reference numerals. In the fourth embodiment described above, the elongated plate-shaped yoke block 10 is arranged so as to come into contact with both end surfaces of the permanent magnet 3 in the circumferential direction. In this configuration, the yoke block 10
Is in contact with both end portions of each of the heat resistant magnet 6 and the high energy magnet 5 in the circumferential direction. The yoke block 10 is made of a material having a large saturation magnetic flux density such as iron or cobalt.

According to this structure, as shown by the arrow in FIG. 6, the excess magnetic flux generated from the high energy magnet 5 flows through the yoke block 10 to both ends of the magnetic pole portion of the retaining ring 4, It is configured to demagnetize by magnetically saturating the part. The configuration of the fourth embodiment other than the above is the same as the configuration of the third embodiment. Therefore, also in the fourth embodiment, the same operation and effect as in the third embodiment can be obtained.

FIG. 7 shows a fifth embodiment of the present invention, and the difference from the first embodiment will be described. The same parts as those of the first embodiment are denoted by the same reference numerals. In the fifth embodiment, the magnet composition component 11 for the high energy magnet is mainly arranged on the inner side, and the magnet composition component 12 for the heat-resistant magnet is mainly arranged on the outer side by the molding die 13 so that the both magnet composition components are arranged. The composite magnet is manufactured by compression molding 11 and 12 and then sintering the molded product. The permanent magnet 3 of the rotor 1 is constructed from this composite magnet, and the permanent magnet 3 is attached to the shaft 2 of the rotor 1.

The composite magnet can be actually manufactured when using a magnet material capable of manufacturing the high energy magnet 5 and the heat resistant magnet 5 by adjusting the components. The molding die 13 is composed of a fixed die 13a and a movable die 13b, and these dies 13a and 13b are configured to form a cavity 13c having the same shape as that of the permanent magnet 3. And the fifth except the above
The configuration of this embodiment is the same as that of the first embodiment.

Therefore, also in the fifth embodiment, the same effect as the first embodiment can be obtained. Especially,
In the fifth embodiment, the permanent magnet of the rotor 1 is composed of the composite magnet manufactured by arranging the magnet composition component 11 for the high energy magnet mainly inside and the magnet composition component 12 for the heat resistant magnet mainly outside. Since No. 3 is configured, unlike the first embodiment in which an interface exists between the high energy magnet 5 and the heat resistant magnet 6, such an interface can be eliminated. Therefore, it is possible to further prevent the permanent magnet 3 from being damaged when a shock occurs during the operation of the electric motor.

FIGS. 8 and 9 show a sixth embodiment of the present invention, and the difference from the fifth embodiment will be described. The same parts as those in the fifth embodiment are denoted by the same reference numerals. In the sixth embodiment, when a composite magnet is manufactured, a large number of small piece-shaped yoke blocks 14 are provided in the outer layer portion composed of the magnet composition component 12 for the heat resistant magnet as shown in FIGS. 8 and 9. It is configured so as to be dispersed and arranged. After disposing the yoke block 14 in a dispersed manner, both magnet composition components 11 and 12 are compression molded, and further, the molded product is sintered to manufacture a composite magnet.
The yoke block 14 is made of a material having a large saturation magnetic flux density, such as iron and cobalt, and is formed to have a circular cross section. The configuration of the sixth embodiment other than the above is the same as the configuration of the fifth embodiment.

Therefore, also in the sixth embodiment, it is possible to obtain the same effect as that of the fifth embodiment. In particular, the sixth
In the above example, when the composite magnet for the permanent magnet 3 is manufactured, the small piece-shaped yoke blocks 14 are dispersedly arranged in the outer layer portion including the magnet composition component 12 for the heat resistant magnet. The magnetic flux generated from the high energy magnet portion of the composite magnet reaches the surface of the rotor 1 through the yoke block 14 and contributes to the rotational force of the rotor 1. Therefore, the magnetic flux density generated in the high energy magnet portion is not attenuated, so that sufficient electric motor performance can be obtained.

Further, in the sixth embodiment, since the small piece-shaped yoke block 14 is configured to have a circular cross section, when the compression molding is performed by the molding die 13 or the compression molded product is obtained, At the time of sintering, it is possible to prevent as much as possible a gap from being formed between the yoke block 14 and the magnet, and it is possible to reduce the occurrence of residual stress and thermal stress. The occurrence of cracks can be prevented as much as possible.

In the sixth embodiment, at least the heat-resistant magnet portion (that is, the outer layer portion composed of the magnet composition component for the heat-resistant magnet) of the composite magnet constituting the permanent magnet 3 is arranged in the circumferential direction. It is preferable to provide yoke blocks at both ends. With this configuration, it is possible to prevent leakage of the magnetic flux that contributes to the rotational force as much as possible. The yoke block is made of a material having a large saturation magnetic flux density such as iron or cobalt. In each of the above embodiments, the present invention is applied to the permanent magnet motor,
Instead, it may be applied to a permanent magnet generator.

[0033]

As is apparent from the above description, the present invention comprises the permanent magnet composed of the high energy magnet arranged inside and the heat resistant magnet arranged outside.
Since the high energy magnet does not demagnetize during shrink fitting,
It has an excellent effect that a high energy magnet can be used as a permanent magnet.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a rotor showing a first embodiment of the present invention.

FIG. 2 is a perspective view of a rotor before attaching a retaining ring.

FIG. 3 is a partial front view of a rotor showing a second embodiment of the present invention.

FIG. 4 is a partial front view of a rotor showing a third embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 4 showing a fourth embodiment of the present invention.

FIG. 6 is a partial front view of the rotor for explaining the operation.

FIG. 7 is a vertical sectional view of a molding die showing a fifth embodiment of the present invention.

FIG. 8 is a view corresponding to FIG. 3 showing a sixth embodiment of the present invention.

FIG. 9 is a cutaway side view of a permanent magnet and a retaining ring.

FIG. 10 is a characteristic diagram showing temperature dependence of a magnetization curve of a high energy magnet.

FIG. 11 is a characteristic diagram showing temperature dependence of a magnetization curve of a heat-resistant magnet.

[Explanation of symbols]

1 is a rotor, 2 is a shaft, 3 is a permanent magnet, 4 is a retaining ring, 5 is a high energy magnet, 6 is a heat resistant magnet, 7 is a split heat resistant magnet, 8 is a yoke block, 9 is a yoke block, 1
Reference numeral 0 is a yoke block, 11 is a magnet composition component for a high energy magnet, 12 is a magnet composition component for a heat resistant magnet, 13 is a mold, and 14 is a yoke block.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuto Sakai 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Keihin Works, Toshiba Corp. (72) Eiji Shimomura 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Stock Company Toshiba Keihin Office

Claims (7)

[Claims] 1. A permanent magnet rotating electric machine comprising a rotor configured by attaching a permanent magnet to a shaft, wherein the permanent magnet comprises a high energy magnet arranged inside and a heat resistant magnet arranged outside. A permanent magnet rotating electric machine characterized by being configured from. 2. The permanent magnet rotating electric machine according to claim 1, further comprising a vibration damping member provided between the high energy magnet and the heat resistant magnet. 3. The permanent magnet rotating electric machine according to claim 1, wherein the heat resistant magnet is divided into a plurality of pieces, and a yoke block is provided between the divided heat resistant magnets. 4. A yoke block is provided at both ends in the circumferential direction of the heat resistant magnet in a structure in which a retaining ring made of a magnetic material is fitted to the outer circumference of the permanent magnet.
4. The permanent magnet rotating electric machine according to any one of 1 to 3. 5. A permanent magnet rotating electric machine comprising a rotor having a shaft to which a permanent magnet is attached, wherein the permanent magnet is mainly arranged inside a magnet composition component for a high energy magnet, and the permanent magnet is for a heat resistant magnet. The permanent magnet is composed of a composite magnet produced by compression-molding both the magnet composition components by a molding die so that the magnet composition components of (1) are mainly arranged outside and then sintering the molded product. Rotating electric machine. 6. A small piece-shaped yoke block is dispersedly arranged in an outer layer portion composed of a magnet composition component for the heat-resistant magnet when the composite magnet is manufactured. Permanent magnet rotating electric machine. 7. A structure in which a retaining ring made of a magnetic material is fitted to the outer periphery of the permanent magnet, and both end portions in the circumferential direction of the outer layer portion of at least the magnet composition component for the heat-resistant magnet of the composite magnet. The permanent magnet rotating electric machine according to claim 5 or 6, wherein a yoke block is provided in the.