GB2089584A - Magnetic rotors for synchronous electric motors - Google Patents
Magnetic rotors for synchronous electric motors Download PDFInfo
- Publication number
- GB2089584A GB2089584A GB8135907A GB8135907A GB2089584A GB 2089584 A GB2089584 A GB 2089584A GB 8135907 A GB8135907 A GB 8135907A GB 8135907 A GB8135907 A GB 8135907A GB 2089584 A GB2089584 A GB 2089584A
- Authority
- GB
- United Kingdom
- Prior art keywords
- rotor
- permanent magnet
- anisotropy
- magnetic
- directions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/278—Surface mounted magnets; Inset magnets
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/2726—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of a single magnet or two or more axially juxtaposed single magnets
- H02K1/2733—Annular magnets
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Permanent Field Magnets Of Synchronous Machinery (AREA)
Abstract
A rotor for a synchronous motor of permanent magnet type consists of a magnetic shaft (6) with a cylindrical anisotropic permanent magnet (7) located coaxially on it. This arrangement minimises rotor diameter while giving the motor a high overload capacity. Figure 30 is a diagram showing the direction of anisotropy of the permanent magnet (7) shown in figure 3A. <IMAGE>
Description
SPECIFICATION
Magnetic rotors for synchronous electric motors
This invention relates to magnetic rotors for synchronous electric motors, in which the rotor includes a permanent magnet.
In conventional rotors for such motors, the rotor diameter is larger than we have found it needs to be, rendering the amount of inertia of the rotor higher than it need be and thus the acceleration performance of the motor worse than it need be.
According to the present invention, there is provided a rotor for a synchronous motor of permanent magnetic type comprising a cylindrical anisotropic permanent magnet located coaxially on a rotor shaft made of a magnetic material.
Preferably the directions of anisotropy of said cylindrical anisotropic permanent magnet are substantially widening in selected one of substantially parallel and parallel forms toward the centre of the rotor shaft from the centre of magnetic poles on the outer periphery of the rotor as seen in cross sectional view.
The cylindrical anisotropic permanent magnet may be of integral construction or it may be made up of a plurality of magnets assembled together.
Such a rotor construction for a synchronous motor of permanent magnet type minimises rotor diameter and gives improved overload capacity.
The present invention and its distinction from the prior art can be seen in more detail from the following description of the accompanying drawings, in which:
Figure 1 A is a cross sectional view of an example of a conventional rotor;
Figure 1 B is a diagram showing the directions of anisotropy of the permanent magnet shown in
Figure 1A; Figure 2A is a cross sectional view of an example of another conventional rotor;
Figure 2B is a diagram showing the direction of anisotropy of the permanent magnet 5 shown in
Figure 2A;
Figure 3A is a cross sectional view showing an embodiment of the present invention;
Figure 3B is a diagram showing the direction of anisotropy of the permanent magnet 7 shown in
Figure 3A;
Figure 4A is a cross sectional view of the rotor according to another embodiment of the present invention;;
Figure 4B is a diagram showing the directions of anisotropy of the permanent magnet 8 shown in Figure 4A;
Figure 5A is a cross sectional view of the rotor according to still another embodiment of the present invention; and
Figure 5B is a diagram showing the directions of anisotropy of the permanent magnet 10 shown in Figure 5A.
First a conventional rotor will be described with reference to Figures 1 and 2. In Figure 1A, reference numeral 1 designates a rotor shaft made of a magnetic material, numeral 2 a permanent magnet having an anisotropic property, and numeral 3 a magnetic pole piece. The direction of anisotropy of the permanent magnet 2 coincides with the thin lines in Figure 1 B.
In Figure 2A, numeral 4 designates a rotor shaft made of a non-magnetic material, numeral 5 a permanent magnet having an anisotropic property, numeral 6 a magnetic pole piece. The direction of anisotropy of the anisotropic permanent magnet coincides with the thin lines shown in Figure 2B.
In the conventional rotors shown in Figures 1 and 2, the space except for the rotary shaft is not fully utilised and therefore the rotor diameter is so large that the moment of inertia is undesirably great, resulting in deteriorated acceleration.
The cross sectional view of a rotor according to an embodiment of the present invention is shown in Figure 3A. Numeral 6 designates a rotor shaft made of a magnetic material, and numeral 7 a cylindrical permanent magnet of anisotropic property. The directions of anisotropy of the anisotropic permanent magnet 7 are substantially widening parallelly toward the centre of the rotor shaft from the centre of the magnetic poles on the outer periphery of the rotor as shown by the thin lines in Figure 3B. In order to meet the demand of an especially sharp acceleration and deceleration performance in practical applications, this rotor has a minimised moment of inertia and a minimised rotor diameter.Further, the current several times larger than the continuous rated current is applied to the armature winding not shown to control the acceleration and deceleration, and therefore a strong magnetomotive force is imposed in various directions on the permanent magnet of the rotor.
As a result, the thickness of the permanent magnet is required to be increased considerably as compared with the thickness of the general magnetic paths taking the magnetic reluctance only of the air gap or the like into consideration in order to improve the demagnetisation characteristic. The diagram of Figure 3 shows a construction taking this point into account, in which the permanent magnet is effectively arranged at all the parts except for the rotor shaft 6 on the one hand and the directions of anisotropy are taken into consideration on the other hand, so that magnetic fluxes to the maximum ability of the permanent magnet are obtainable, thus reducing the diameter of the rotor. Further, since the thickness of the cylindrical permanent magnet is increased, the demagnetisation characteristic is improved thereby to improve the overload capacity.
Another embodiment of the present invention is shown in Figure 4A. For the reasons of production of the permanent magnet, four pieces of permanent magnets 8 are combined to construct a rotor. Numerai 9 designates a ring for securing the permanent magnets 8. The directions of anisotropy of the permanent magnets 8 are shown
by the thin lines of Figure 4B, which are coincidental with the thin lines of Figure 3B.
Still another embodiment of the present invention is shown in Figure 5A. In this embodiment, the permanent magnets 8 of Figure 4 are replaced by permanent magnets 10 of different directions of anisotropy combined to form a rotor. The directions of anisotropy of the permanent magnets 10 are along the thin lines shown in Figure 5B. This rotor does not require any special magnet and therefore may be produced easily.
It will be understood from the foregoing description that according to the present invention the permanent magnets are arranged effectively over almost all the parts of the rotor on the one hand and the rotor is constructed taking the directions of anisotropy of the permanent magnets into consideration on the other hand, so that the magnetic fluxes are obtained to the maximum ability of the permanent magnets. As a result, it is possible to reduce the diameter of the rotor for a decreased moment of inertia, thus further improving the control of acceleration and deceleration.
Claims (5)
1. A rotor for a synchronous motor of permanent magnet type comprising a cylindrical anisotropic permanent magnet located coaxially on a rotor shaft made of a magnetic material.
2. A rotor according to claim 1, in which the directions of anisotropy of said cylindrical anisotropic permanent magnet are substantially widening in selected one of substantially parallel and parallel forms toward the centre of the rotor shaft from the centre of magnetic poles on the outer periphery of the rotor as seen in cross sectional view.
3. A rotor according to claim 2, in which the cylindrical anisotropic permanent magnet is not integral and is made up of a plurality of magnets.
4. A rotor for a synchronous motor of permanent magnet type substantially as hereinbefore described with reference to Figures 3A and 3B, 4A and 4B or 5A and 5B.
5. A synchronous electric motor including a permanent magnet type rotor according to any one of the preceding claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55168638A JPS5795169A (en) | 1980-11-29 | 1980-11-29 | Rotor for synchronous motor with permanent magnet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2089584A true GB2089584A (en) | 1982-06-23 |
| GB2089584B GB2089584B (en) | 1985-06-05 |
Family
ID=15871743
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8135907A Expired GB2089584B (en) | 1980-11-29 | 1981-11-27 | Magnetic rotors for synchronous electric motors |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5795169A (en) |
| DE (1) | DE3147102C2 (en) |
| GB (1) | GB2089584B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999012248A1 (en) * | 1997-08-28 | 1999-03-11 | Empresa Brasileira De Compressores S.A. - Embraco | An electric motor rotor |
| EP0923804A1 (en) * | 1996-09-04 | 1999-06-23 | Quantum Corporation | Methods and apparatus for improved dc motors and magnetic clutches |
| GB2333906A (en) * | 1998-01-30 | 1999-08-04 | Aisin Seiki | Austenitic/Martensitic rotor for a reluctance machine |
| US7042126B2 (en) | 2003-05-08 | 2006-05-09 | Corac Group Plc | Rotary electric machine |
| EP3451502A1 (en) * | 2017-08-30 | 2019-03-06 | Lakeview Innovation Ltd. | Multipolar rotor with loaf-shaped or pie segment permanent magnets |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5992758A (en) * | 1982-11-17 | 1984-05-29 | Toshiba Corp | Brushless motor |
| EP0386239A4 (en) * | 1988-08-19 | 1991-01-16 | Nauchno-Proizvodstvennoe Obiedinenie "Magneton" | Multipole rotor of electric machine |
| KR100301517B1 (en) * | 1999-07-23 | 2001-11-01 | 구자홍 | Rotor for brushless d.c motor |
| CN105915011A (en) * | 2016-06-27 | 2016-08-31 | 江西东江机电有限公司 | Vacuum pump brushless motor of automobile brake system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1938162U (en) * | 1966-03-10 | 1966-05-12 | Heinz Ahlswede | OXYD MAGNET RUNNER FOR OXYD RUNNER MOTORS. |
| JPS49111102A (en) * | 1973-02-27 | 1974-10-23 |
-
1980
- 1980-11-29 JP JP55168638A patent/JPS5795169A/en active Pending
-
1981
- 1981-11-27 DE DE3147102A patent/DE3147102C2/en not_active Expired
- 1981-11-27 GB GB8135907A patent/GB2089584B/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0923804A1 (en) * | 1996-09-04 | 1999-06-23 | Quantum Corporation | Methods and apparatus for improved dc motors and magnetic clutches |
| EP0923804A4 (en) * | 1996-09-04 | 2001-11-14 | Quantum Corp | Methods and apparatus for improved dc motors and magnetic clutches |
| WO1999012248A1 (en) * | 1997-08-28 | 1999-03-11 | Empresa Brasileira De Compressores S.A. - Embraco | An electric motor rotor |
| GB2333906A (en) * | 1998-01-30 | 1999-08-04 | Aisin Seiki | Austenitic/Martensitic rotor for a reluctance machine |
| US7042126B2 (en) | 2003-05-08 | 2006-05-09 | Corac Group Plc | Rotary electric machine |
| EP3451502A1 (en) * | 2017-08-30 | 2019-03-06 | Lakeview Innovation Ltd. | Multipolar rotor with loaf-shaped or pie segment permanent magnets |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3147102A1 (en) | 1982-07-22 |
| JPS5795169A (en) | 1982-06-12 |
| GB2089584B (en) | 1985-06-05 |
| DE3147102C2 (en) | 1984-07-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19921127 |