ACTIVE RADIAL MAGNETIC BEARING WITH YOKE WINDING

Abstract

A radial magnetic bearing includes an axis, a stator, and a rotor. The stator includes at least two stator assemblies axially spaced from one another. Each of the stator assemblies includes a magnetically soft core. At least one of the stator assemblies includes a magnetically soft core with several radially projecting teeth arranged distributed in a circumferential direction, and several coils likewise arranged distributed in the circumferential direction. Two respective teeth of the magnetically soft core that are successive in a circumferential direction are connected to each other by way of a connecting section of the core. A permanent magnet assembly is disposed axially between the two magnetically soft cores. The stator assembly is configured such that one of the respective connecting sections is wound with one of the respective coils. The permanent magnet assembly is part of the rotor.

Claims

1. A radial magnetic bearing comprising: an axis, a stator; and a rotor, wherein said stator includes at least two stator assemblies axially spaced from one another, where each of said stator assemblies includes a magnetically soft core; wherein at least one of said stator assemblies includes one said magnetically soft core with several radially projecting teeth arranged distributed in a circumferential direction, and several coils likewise arranged distributed in the circumferential direction, and where two respective teeth of said magnetically soft core that are successive in a circumferential direction are connected to each other by way of a connecting section of said core; wherein a permanent magnet assembly is disposed axially between said two magnetically soft cores; and the stator assembly being configured such that one of said respective connecting sections is wound with one of said respective coils wherein said permanent magnet assembly is part of said rotor.

2. The radial magnetic bearing according to claim 1, wherein all of said stator assemblies are embodied such that their magnetically soft core comprises: several radially projecting teeth arranged distributed in the circumferential direction, where two respective teeth of said magnetically soft core that are successive in the circumferential direction are connected to each other by way of a connecting section of said core, and where one respective connecting section is wound with one respective coil.

3. The radial magnetic bearing according to claim 2, wherein said rotor comprises: an outer hollow cylindrical part and an inner part, where said outer hollow cylindrical part is embodied as a magnetically soft laminated sheet package, and where said inner part of said rotor is embodied as a solid magnetically soft circuit yoke.

4. The radial magnetic bearing according to claim 1, wherein said permanent magnet assembly comprises: a continuous axially magnetized permanent magnet.

5. The radial magnetic bearing according to claim 1, wherein each of said magnetically soft cores comprises: four or six teeth each.

6. The radial magnetic bearing according to claim 1, wherein more than two stator assemblies are provided, where a permanent magnet assembly is respectively arranged between two axially successive stator assemblies.

7. The radial magnetic bearing according to claim 1, wherein said connecting sections are each configured as a ring segment.

8. The radial magnetic bearing according to claim 1, wherein said connecting sections extend rectilinear and in a tangential direction.

9. The radial magnetic bearing according to claim 1, wherein said teeth project both radially outwardly as well as radially inwardly.

10. The radial magnetic bearing according to claim 1, wherein said permanent magnet assembly is configured with a rare earth magnet.

11. The radial magnetic bearing according to claim 1, wherein said magnetically soft core consists of: a laminated sheet package or of magnetically soft composite material.

12. The radial magnetic bearing according to claim 1, wherein said rotor comprises: an outer hollow cylindrical part and an inner part, where said outer hollow cylindrical part is embodied as a magnetically soft laminated sheet package, and where said inner part of said rotor is embodied as a solid magnetically soft circuit yoke.

13. The radial magnetic bearing according to claim 12, wherein the permanent magnet assembly has a through-hole through which the outer hollow cylindrical part and the inner part pass.

14. The radial magnetic bearing according to claim 12, wherein the outer hollow cylindrical part and the inner part are each divided by the permanent magnet assembly.

15. The radial magnetic bearing according to claim 14, wherein the permanent magnet assembly is located axially between the two laminated sheet packages of the stator.

Description

[0026] Embodiments of the present invention are explained in more detail below with reference to drawings, where

[0027] FIG. 1: shows an oblique view of a radial magnetic bearing according to a first embodiment,

[0028] FIG. 2: shows a longitudinal sectional view of the radial magnetic bearing of FIG. 1 along section line II shown in FIG. 3,

[0029] FIG. 3: shows a cross sectional view through the radial magnetic bearing of FIGS. 1 and 2 along section line III shown in FIG. 2,

[0030] FIG. 4: shows a longitudinal sectional view through a radial magnetic bearing according to a second embodiment,

[0031] FIG. 5: shows a longitudinal sectional view through a radial magnetic bearing according to a third embodiment,

[0032] FIG. 6: shows a longitudinal sectional view through a radial magnetic bearing according to a fourth embodiment, and

[0033] FIG. 7: shows a longitudinal sectional view through a radial magnetic bearing according to a fifth embodiment.

[0034] It applies to the following embodiments that like parts are designated by like reference numerals. Where a figure contains reference numerals which are not explained in more detail in the associated figure description, then reference is made to preceding or subsequent figure descriptions.

[0035] FIGS. 1 to 3 show a first embodiment of a radial magnetic bearing 1 according to the invention. The magnetic bearing comprises an outer stator 3 and an inner rotor 4. Stator 3 and rotor 4 are arranged coaxially to each other. They are therefore both configured to be substantially rotationally symmetrical to a common axis 2 of the magnetic bearing.

[0036] As shown in particular in FIG. 2, stator 3 comprises two stator assemblies 5 which are axially spaced apart from one another. Each of the two stator assemblies 5 comprises a magnetically soft core 6. The magnetically soft cores are each configured as a magnetically soft laminated sheet package in the embodiment illustrated but can also be made of magnetically soft composite material. It can be seen in FIG. 1 that each of the two magnetically soft laminated sheet packages 6 comprises several teeth 7 arranged distributed in the circumferential direction. In the embodiment shown, a total of six teeth are provided for every laminated sheet package. Teeth 7 are at a uniform distance from each other in the circumferential direction and are connected to each other by way of yoke-like connecting sections 9. Connecting sections 9 are configured as ring segments and together with center parts of the teeth form a closed circular ring, from which an outer part 15 of the tooth projects radially outwardly, and an inner part 16 of the tooth projects radially inwardly at every tooth, respectively.

[0037] Each of the two stator assemblies further comprises a total of six coils 8. Coils 8 together form a stator winding which can be energized accordingly to generate a net force acting in the radial direction upon rotor 4 of the magnetic bearing. Coils 8 are shown only schematically in the illustrations and can completely fill the gap between the radially projecting parts of the teeth. They are preferably wound onto the connecting sections by use of a toroidal winding machine. With respect to the axis of the magnetic bearing, the axis of each coil extends in the circumferential direction or tangentially, respectively.

[0038] Disposed axially between the two magnetically soft laminated sheet packages 6 is a permanent magnet assembly 10 of stator 3. Permanent magnet assembly 10 consists of a total of six single block-shaped permanent magnets 11 which are magnetized in the axial direction with respect to axis 2 of the magnetic bearing. The 6 single magnets are arranged between teeth 7 of magnetically soft laminated sheet packages 6 such that single magnets 11 and teeth 7 are aligned with each other in the axial direction

[0039] FIGS. 2 and 3 show that rotor 4 of magnetic bearing 1 according to the invention consists of an outer hollow cylindrical part 12 and an inner part 13. Outer hollow cylindrical part 12 is configured as a magnetically soft laminated sheet package in order to prevent eddy currents in the outer region of the rotor. Inner part 13 of the rotor is configured as a solid magnetically soft circuit yoke to axially conduct the magnetic flow generated in the stator.

[0040] It can be seen in the cross-sectional view according to FIG. 3 that teeth 7 of the magnetically soft laminated sheet packages and single magnets 11 arranged between the two laminated sheet packages have substantially the same cross-section. In order to keep the procurement costs for the single magnets low, they are configured as simple cuboid blocks. Teeth 7 of laminated sheet packages 6 differ from the single magnets in their shape only in that they nestle with their end facing the axis against the outer circumference of the rotor. Regardless of this, there is of course a certain air gap between teeth 7 and the outer circumference of the rotor.

[0041] FIG. 4 shows a radial magnetic bearing 1 according to a further embodiment of the present invention. The illustration shows a longitudinal sectional view similar to FIG. 2. The structure in the center region of magnetic bearing 1 is basically the same as in the embodiment of FIGS. 1 to 3. The difference to the embodiment of FIGS. 1 to 3 is that two additional permanent magnet assemblies 10 are provided. The two additional permanent magnet assemblies 10 are located at the two axial ends of the magnetic bearing. The magnetic bearing at the two respective axial ends therefore terminates with a permanent magnet assembly. The rotor of the magnetic bearing must accordingly be configured to be longer. The magnetic flow is completed at the two axial ends of the magnetic bearing via the air. The embodiment shown in FIG. 4 by way of example represents a number of conceivable embodiments with an arbitrary number of stator assemblies. Because the two permanent magnet assemblies 10 can be adjoined by further stator assemblies.

[0042] FIG. 5 shows a further embodiment of a radial magnetic bearing 1 according to the invention. The illustration again shows a longitudinal sectional view similar to FIGS. 2 and 4. In contrast to the embodiment from FIGS. 1 to 3, permanent magnet assembly 10 arranged between the two stator assemblies 5 is not part of the stator but part of the rotor. It consists of a single permanent magnet ring 14 which is firmly connected to the other components of the rotor. Permanent magnet ring 14 has a through-bore through which outer and inner parts 12, 13 of the rotor shaft extend.

[0043] FIG. 6 shows a further embodiment of a radial magnetic bearing 1 according to the invention. In this embodiment, stator 3 is configured in the same way as in the embodiment of FIGS. 1 to 3. Inner part 13 and outer hollow cylindrical part 12 of rotor 4, however, are interrupted at the center by a permanent magnet ring 14 which is part of the rotor, similar to the embodiment of FIG. 5. Permanent magnet ring 14 is likewise axially magnetized and is located axially between two laminated sheet packages 6 of the stator, although the outer diameter of the permanent magnet ring is smaller than the inner diameter of hollow cylindrical laminated sheet packages 6. The outer diameter of permanent magnet ring 14 is at most equal to the outer diameter of the magnetically soft rotor parts. Disposed radially outside permanent magnet ring 14 are single magnets 11 on the stator side. The embodiment of FIG. 6 differs from the embodiment of FIGS. 1 to 3 additionally in that the rotor comprises a central shaft 17 which extends through a corresponding bore of inner part 13 of the rotor and of permanent magnet ring 14.

[0044] FIG. 7 shows a further embodiment of a radial magnetic bearing 1 according to the invention. This embodiment differs from the embodiment of FIG. 6 in that no single magnets are provided on the stator side. No permanent magnet assembly is therefore present on the stator side. The permanent magnet assembly there consists only of permanent magnet ring 14 on the rotor side. Single magnets 11 are replaced in this embodiment by magnetically soft blocks 18 which consist of stacked radially or tangentially extending magnetically soft plates or of magnetically soft composite material. Magnetically soft blocks 18 can be connected to magnetically soft cores 6 in a positive substance-fit manner. It is also possible to embody magnetically soft blocks 18 as part of at least one of magnetically soft cores 6.