DE102007036603A1 - Planar high temperature superconducting bearing for e.g. electric motor, has high temperature superconductor and permanent magnet arrangement whose front sides are set opposite to each other, and axially movable stator connected with guide - Google Patents

Abstract

The bearing has a rotor (1) mounted on a shaft (2), and a permanent magnet arrangement (3) provided at a front side of the rotor, where the magnet arrangement concentrically surrounds the shaft. A high temperature superconductor (6) is arranged in a stator (4) fixed opposite to the magnet arrangement. Planar front sides of the superconductor and the magnet arrangement are fixed opposite to each other, and distance between the superconductor and the magnet arrangement forms a magnetically active bearing gap (8). The stator is axially moved and connected with a guide (10) i.e. linear guide. An independent claim is also included for a method for compensating thermal linear expansion of a shaft of a rotor.

Description

The The present invention relates to high temperature superconductor bearings a rotor surrounded by a stator with a high temperature superconductor is, wherein the rotor by magnetic forces in one floating state is maintained.

HTS bearings are characterized by a front side in all directions self-stable non-contact operation, thereby offering a great Smooth running and low maintenance.

The Use of the levitation effect between a magnetic field (excitation by permanent magnets or current coils) and a high-temperature superconductor (HTS) to build a non-contact bearing (superconductor magnetic bearing, SMB) of linear or rotating systems known for several years.

in principle contains such a high-temperature superconductor bearing (HTS bearing) a permanent magnet arrangement as excitation system and a high-temperature superconductor, wherein the high temperature superconductor of the magnetic flux of Permanent magnet arrangement is penetrated.

Becomes now the high-temperature superconductor to a temperature below cooled to its critical temperature Tc, it becomes pervasive frozen magnetic flux. In case of a change of position Forces generated, which counteract the change in position Act. These forces can be disgusting or attractive, but in any case are directed that they are against a change in position from the cooling position Counteract out.

There the size of these forces increasing Distance from excitation system and high-temperature superconductor decreases, This distance should be as high as possible to achieve Forces are kept as small as possible.

to Increasing the magnetic flux density may be the permanent magnet arrangement be designed as a so-called collector arrangement, with between the individual permanent magnets of the permanent magnet arrangement ferromagnetic flux guide pieces, z. B. iron poles are arranged.

HTS bearings can be used for non-contact storage of rotating Systems are used. These bearings are made in principle a fixed part, the stator, and a rotating part, the rotor. Usually, the stator contains the high-temperature superconductor and the rotor is provided with the permanent magnet assembly which acts as a pathogen system. The magnetization of the permanent magnets is chosen so that the distribution of the magnetic flux remains unchanged around the axis of rotation during rotation and no forces are caused by the rotation itself.

The high-temperature superconductor is located in a cryostat or similar cooling device for cooling. For thermal insulation of the cooled elements of the stator, in particular the high-temperature superconductor, vacuum is applied to the cryostat. An example of the structure and mode of operation of HTS bearings is given in the European patent application EP 1 767 798 A1 as well as on WO 02/06688 A1 referred to, which is incorporated herein by reference.

in principle can be HTS bearings with a cylindrical or planar arrangement be differentiated.

In a cylindrical arrangement, the permanent magnets are coaxial arranged along the rotor shaft. The rotor shaft with the on it arranged permanent magnet is cylindrical of the Surrounded by high-temperature superconductor, with the cylindrical High-temperature superconductor in a likewise cylindrical Cryostat is located. The rotor shaft is located with the permanent magnet in the so-called warm bore of the cryostat. In a cylindrical Arrangement are the opposite ends the high temperature superconductor and the permanent magnet assembly curved.

In a planar arrangement is a rotor with planar end faces arranged concentrically on a rotor shaft. The front sides of the Rotors have permanent magnets concentrically around the shaft are arranged around. The stator of the bearing has high temperature superconductors and a surrounding cryostat housing with vacuum envelope on. The high-temperature superconductors are the end faces of the rotor arranged opposite to the permanent magnet arrangement and concentrically surround the rotor shaft parallel to the permanent magnets.

Of the the bearing forces determining distance, also magnetically effective Called gap between the excitation system and the high-temperature superconductor sets itself from the insulating gap in the cryostat between the inner wall of the cryostat and face of the high-temperature superconductor, the wall thickness of the cryostat and the air gap between the outer wall of the cryostat and front of the exciter system together. In today Arrangements is the dimension of the magnetically effective Gap of such a bearing assembly about 3 mm, the dimension the above-mentioned part distances each about 1 mm is.

In a plain bearing of the above ge The arrangement rotates the rotor radially about the shaft, wherein a radial deflection of the rotor is counteracted by correspondingly radial magnetization of the permanent magnets.

As a general rule it comes in bearings with a rotor mounted on a rotor shaft in operation to a thermal expansion of the rotor shaft. The Extent of length expansion depends on it other from the shaft temperature.

In a 3 meter long wave with a wave temperature of 100 to 150 ° C is the thermal expansion typically 5 to 10 mm.

This As a result, in a fixed bearing of the magnetic effective gap can be increased accordingly must be to contact the permanent magnet assembly with the outer wall of the cryostat housing. Such a drastic Magnification of the magnetically effective gap would lead to a significant reduction in specific load capacity of the camp or to increase the use of superconducting Material to maintain the carrying capacity.

It It was therefore an object of the present invention to provide a planar high-temperature superconductor bearing for To provide a simple compensation of the Length expansion of the rotor shaft allows without a Magnification of the magnetically effective gap is required.

According to the invention solved this task by putting in a planar HTS bearing the stator mounted axially displaceable on a guide is, and the stator due to the axial forces due to the axial displacement of the shaft occur, axially tracked becomes.

following the present invention with reference to the accompanying figures, which Embodiments of the invention show, closer clarified.

It shows

1 schematically a longitudinal HTS bearing according to the invention in a longitudinal section;

2 schematically an embodiment of the invention with fixed bearing / movable bearing arrangement.

This in 1 shown HTS bearing with a planar structure has a rotor 1 with planar faces on, concentric to a wave 2 is attached. The faces have permanent magnets 3 on, concentrically around the rotor 1 are arranged around, and wherein the permanent magnets 3 are arranged radially one behind the other.

According to the invention preferred the permanent magnet arrangement is designed as a collector arrangement.

The permanent magnets can have the shape of rings around the shaft 2 to run around. The rings can be one-piece. In general, however, they can be composed of curved segment pieces.

In the embodiment shown here are the permanent magnets 3 magnetized opposite, where N stands for the North Pole and S for the South Pole.

The rotor 1 with the permanent magnets 3 is from a stator 4 surrounded, which also around the wave 2 is arranged.

The stator 4 has a vacuum envelope 5 on. Inside the vacuum envelope 5 are high-temperature superconductors 6 whose planar end faces the planar end faces of the permanent magnet arrangement 3 are arranged opposite one another. The high-temperature superconductors 6 are on a support structure 7 applied.

The distance between the front of the high-temperature superconductor 6 and the end face of the respective opposite permanent magnet arrangement 3 forms the magnetic forces acting on the bearing forces 8th ,

In the bearing shown here, the magnetization of the permanent magnets is selected such that the bearing has a high radial rigidity. A possible position change of the rotor 1 in the radial direction thus generates a corresponding restoring force in the opposite direction, so that the rotor 1 securely held in its radial position. The rotation of the rotor 1 around the shaft 2 around it leads to no change of the magnetic flux, so that by the rotation itself no forces are generated, which would counteract the rotation.

In operation, there is a thermal expansion of the rotor 2 in the axial direction and as a result of this thermal expansion of the shaft 2 to an axial displacement of the rotor 1 and thus to an approximation of the end face of the permanent magnet assembly 3 to the outer wall of the vacuum envelope 5 of the stator 4 ,

Since the amount of thermal expansion is generally greater than the air gap 9 between the end face of the permanent magnet arrangement 3 and outer wall of the vacuum envelope 5 , there is a contact between the permanent magnet 3 and vacuum envelope 5 and thus to the disturbance of La gers.

An enlargement of the air gap 9 is undesirable from a practical point of view, as it would significantly affect the bearing forces. Nevertheless, sufficient bearing forces at an enlarged air gap 9 To be able to, would be used according to more superconducting material, which would lead to a significant increase in costs.

The However, magnetization of the permanent magnet arrangement leads not only with radial position change, but also at axial position change to a change the magnetic field and thus to generate corresponding restoring forces, which counteract the respective position change.

An axial displacement of the rotor 1 due to a thermal expansion of the shaft 2 thus causes the formation of a corresponding axial restoring force.

The present invention takes advantage of the fact that also the axial displacement of the rotating part to a power transmission to the stator 4 with the high-temperature superconductors leads. For this purpose, the stator 4 axially displaceable with a guide 10 connected. Due to the axial displaceability of the stator 4 The axial forces, which are associated with a displacement of the shaft, lead to an axial displacement of the stator 4 until the balance. The air gap 9 can thus be limited to the minimum necessary for manufacturing tolerances without a possibly occurring axial displacement of the rotor 1 must be taken into account.

The leadership 10 can be formed as a linear guide with ball bush as shown schematically in the figure.

2 shows an application form of a high-temperature superconductor bearing assembly according to the invention.

In the 2 shown application form has two high-temperature superconductor bearings 14 . 15 on that in the area of the opposite ends of the shaft 2 are arranged. In the embodiment shown here, the high temperature superconductor bearings are made axially on the shaft 2 alternately arranged in succession rotors 2 with permanent magnet arrangement 3 and stators 4 formed with cryostat and high temperature superconductor.

The rotors 1 In the embodiment shown here are magnetic rotors, which are formed from the permanent magnet assembly and the collector assembly.

That in the 2 High-temperature superconductor bearing shown on the left 14 is designed as a fixed bearing and is therefore not axially displaceable.

In contrast, this is in 2 right high-temperature superconductor 15 designed as a floating bearing and is axially displaceable.

The floating bearing 15 is stuck with a guide 10 connected. The leadership 10 is designed in the embodiment shown here as a linear guide and has a bearing block 11 , a wave 12 and a sliding sleeve 13 on. The sliding sleeve 13 Again, with the cryostat housing of the stators 4 connected.

Now the shaft is stretching 2 in operation in the axial direction, the length can be extended by automatic tracking of the floating bearing 15 be compensated.

Next a fixed bearing / floating bearing assembly is the present invention for movable bearings / movable bearing arrangements alike suitable.

The present invention is suitable for. B. for use in fast running electric motors, compressors, etc.

According to a further embodiment, in the intermediate space between the inner wall of the vacuum envelope 5 and surface of the high-temperature superconductor 6 one or more spacers may be provided which allow for possible bending of the vacuum envelope 5 due to the pressure differences that occur during evacuation of the cryostat, prevent.

Of the Spacer can, for example, from an airgel as ienem silicate airgel or a structure of fiber reinforced plastic, such as be formed glass or carbon reinforced plastic.

The present invention is based on the fact that an HTS bearing is a self-aligning assembly, which bearing tries to maintain the magnetically effective gap set during the cooling process 8th maintain. Ie. at one on the motor shaft 2 fixed rotor 1 which is the stator 4 with the superconductors 6 is opposite in the cooled state holds the HTS bearing according to the invention with movably constructed stator this gap 8th at. By training at least one HTS shaft bearing as a floating bearing, so that the stator 4 can align itself with the rotor fixed, compensated for the bearing assembly in the shaft 2 generated linear expansion itself.

1

rotor

2

wave

3

Permanent magnet assembly

4

stator

5

vacuum envelope

6

High temperature superconductors

7

support structure

8th

bearing gap

9

air gap

10

guide

11

bearing block the linear guide

12

wave the linear guide

13

sliding sleeve

14

fixed bearing

15

movable bearing

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1767798 A1 [0009]
• WO 02/06688 A1 [0009]

Claims (4)

High-temperature superconductor bearing with a planar arrangement, comprising a rotor ( 1 ) standing on a wave ( 2 ) and a stator ( 4 ), wherein the end faces of the rotor ( 1 ) each have a permanent magnet arrangement ( 3 ) concentrically the rotor shaft ( 2 ) and where in the stator ( 4 ), the permanent magnet arrangement ( 3 ) opposite, high temperature superconductors ( 6 ), wherein the planar end faces of the high-temperature superconductors ( 6 ) and the permanent magnet arrangement ( 3 ), and the distance between high-temperature superconductors ( 6 ) and permanent magnet arrangement ( 3 ) the magnetically active bearing gap ( 8th ), wherein the stator ( 4 ) axially displaceable and with a guide ( 10 ) connected is. High-temperature superconductor bearing according to claim 1, wherein the guide ( 10 ) is designed as a linear guide. Method for compensating the thermal expansion of a rotor shaft ( 2 ) in a planar high-temperature superconductor bearing, wherein upon axial displacement of the shaft ( 2 ) due to thermal expansion of an axially displaceable ausgestalteter stator ( 4 ) by the with the thermal expansion of the shaft ( 2 ) is displaced to compensate for axial forces, and the air gap ( 9 ) between vacuum envelope ( 5 ) of the stator ( 4 ) and permanent magnet arrangement ( 3 ) is maintained. Use of a planar high temperature superconductor bearing according to claim 1 or 2 in electric motors and compressors.