DE102007036603B4 - High temperature superconductor bearing with improved bearing tracking - 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 a floating state is held.

HTS bearings are characterized by a front side in all directions self-stable contactless Operation and thus offer a great quietness 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 Storage (superconductor magnetic bearing, SMB) of linear or rotating systems has been known for several years.

in principle contains such a high temperature superconductor bearing (HTS bearing) a permanent magnet assembly as a pathogen system and a high-temperature superconductor, wherein the High temperature superconductor of the magnetic flux of the permanent magnet assembly is penetrated. Will now the high temperature superconductor to a Temperature is cooled below its critical temperature Tc, the frozen him penetrating magnetic flux. In case of a change of position forces are generated, the change of position counteract. These forces can repulsive or attractive, but in any case are directed that they are against a change of position from the cooling position Counteract out. Because the size of these forces with increasing distance from exciter system and high temperature superconductors decreasing, this distance should be as possible to achieve high forces preferably kept small.

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

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

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 HTS bearings with cylindrical or planar arrangement distinguished become.

In a cylindrical arrangement, the permanent magnets are coaxial arranged along the rotor shaft. The rotor shaft with the on it arranged permanent magnets is cylindrical from the high temperature superconductor surrounded, wherein 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 End faces of the high temperature superconductor and the permanent magnet assembly curved.

In a planar arrangement is a rotor with flat 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 front sides of the rotor with the permanent magnet arrangement arranged opposite and surrounded concentric with the rotor, the rotor shaft parallel to the permanent magnet.

Of the the bearing forces determining distance, also called magnetically effective gap between the Excitation system and the high-temperature superconductor sits down with it 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 Cryostats and the air gap between the outer wall of the cryostat and Front side of the pathogen system together. In today's arrangements is the dimension of the magnetically effective gap of such a bearing assembly about 3 mm, the dimension of the above part distances each about 1 mm.

EP 1 767 798 A1 describes a planar bearing configuration, wherein the activation of the bearing takes place by utilizing lateral forces. To activate is a change in the positional relationship of the high-temperature superconductor and the permanent mag Netanordnung in the cooling phase against the positional relationship in the operating phase required. This change in the positional relationship takes place here by the stator is brought with the high-temperature superconductor by radial displacement in the cooling position. There is no automatic tracking of the stator components in a change in the positional relationship of the high-temperature superconductor to the permanent magnet as a result of thermal expansion of the rotor shaft during operation.

WO 2002/06688 A1 relates to a cylindrical high-temperature superconductor arrangement, wherein the high-temperature superconductor coaxially surrounds the rotor part with permanent magnet arrangement. The required for activation positional change is achieved here by the high-temperature superconducting cylinder is carried out in two half-shells, wherein the two half-shells are brought into the cooling position by being moved radially away from each other by means of an actuator. An automatic tracking of the stator components in a change of the positional relationship during operation is not provided.

DE 198 50 421 A1 also relates to a cylindrical bearing assembly wherein a cylindrical high temperature superconductor coaxially surrounds the permanent magnet assembly on the rotor shaft. The object here is an adjusting device for adjusting the axis of the rotor shaft on the geometric axis of the inner bore of a stator and for adjusting the air gap required for non-contact storage.

EP 0 858 691 B1 relates to passive magnetic bearings, which are composed of permanent magnets. As it turned out EP 0 858 691 results in a complete passive storage of a body is nothing stable. At least one degree of freedom must be blocked in another way. This "blocking" is done by means of other forces-generating components that maintain the balance. By a special arrangement of the permanent magnets is prevented that the stored object, for example due to temperature changes, is deflected from the equilibrium position. It is a conventional magnetic bearing, the deflection from an equilibrium position by providing corresponding elements is prevented.

In rotates a planar bearing of the above arrangements the rotor radially around the while, wherein a radial deflection of the Rotor by corresponding radial magnetization of the permanent magnets counteracted.

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 Linear 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 Linear expansion typically 5 to 10 mm.

This As a result, in a fixed bearing of the magnetic effective gap must be increased accordingly to one Contact the permanent magnet assembly with the outer wall of the cryostat to avoid. Such a drastic enlargement of the magnetically effective Split would to a significant reduction of the specific load capacity of the camp or to an increase the use of superconducting material for maintaining the load capacity to lead.

It It was therefore an object of the present invention to provide a planar high-temperature superconductor bearing for disposal to make that a simple compensation of the linear expansion of the rotor shaft allowed without an enlargement of the magnetically effective gap is required.

According to the invention this Problem solved by the features of claim 1. The dependent claim a preferred embodiment. Further The present invention relates to a method for compensation the thermal expansion a rotor shaft in a planar high temperature superconductor bearing.

following the present invention with reference to the accompanying figures, which embodiments of the invention show in more detail 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 but 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 the camp.

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.

However, the magnetization of the permanent magnet arrangement not only leads to a change in the radial position, but also in the axial position change to a change of 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 floating bearing / movable bearing arrangements equally 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 may for example consist of an airgel such as a silicate airgel or a structure made of fiber-reinforced Plastic, be formed as 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

Claims (3)

High temperature superconductor bearing assembly with planar bearing configuration and at least two planar magnetic bearings ( 14 . 15 ), the magnetic bearings ( 14 . 15 ) a rotor ( 1 ) mounted on a rotor shaft ( 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 to form a magnetically active bearing gap ( 8th ), and wherein a magnetic bearing as a fixed fixed bearing ( 14 ) with fixed stator components and the other magnetic bearings ( 15 ) are formed as floating bearing with movable stator components, wherein the stator components of the magnetic bearing designed as a floating bearing ( 15 ) in the operating state in the direction of the rotor shaft ( 2 ), depending on a in the direction of the rotor shaft ( 2 ) positional change of the bearing components of the rotor ( 1 ), while maintaining a constant positional relationship of the bearing components of the trained as a floating bearing magnetic bearing ( 15 ), and wherein the stator ( 4 ) designed as a floating bearing magnetic bearing ( 15 ) with a guided tour ( 10 ) connected is. High-temperature superconductor bearing assembly 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 with at least two planar magnetic bearings ( 14 . 15 ), the magnetic bearings ( 14 . 15 ) a rotor ( 1 ) mounted on a rotor shaft ( 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 ) to be ordered, so that the planar faces of the high-temperature superconductors ( 6 ) and the permanent magnet arrangement to form a magnetically active bearing gap ( 8th ), and wherein a magnetic bearing ( 14 ) as a fixed bearing with stationary stator components and the other magnetic bearing as a floating bearing ( 15 ) are formed with movable stator components, so that upon axial displacement of the rotor shaft ( 2 ) due to thermal expansion in the operating state, the stator components of the floating bearing ( 15 ) by the with the thermal expansion of the rotor shaft ( 2 ) associated axial forces while maintaining a constant positional relationship of the bearing components of the designed as a floating bearing magnetic bearing ( 15 ) are tracked.