DEVICE FOR IMPROVING THE VACUUM IN THE HOUSING OF A MACHINE

Abstract

The disclosure relates to a device for improving a vacuum in the housing of a machine, in particular a centrifugal-mass energy store, comprising a rotor, for example a shaft having a centrifugal mass arranged thereon, which rotor is supported on at least one superconducting bearing in a contactless manner and is arranged in a vacuum container. In order to maintain the operating state of the superconducting bearing, the superconducting bearing is thermally connected to a cold source cooled by a cryogenic medium. According to the invention, the vacuum in the vacuum container is improved by means of an adsorber thermally connected to a cooling apparatus. The cooling of the adsorber occurs preferably by means of evaporated cooling medium from the superconducting bearing.

Claims

1. A device for improving a vacuum in the housing of a machine, in which a rotor, which is contactlessly mounted on at least one superconducting bearing, is arranged in a vacuum container, wherein the superconducting bearing, in order to maintain its operating state, is thermally connected to a cold source cooled by a cryogenic medium, and in which there are provided means for improving the vacuum in the vacuum container, wherein an adsorber that is thermally connected to a cooling device is provided as the means for improving the vacuum.

2. The device as claimed in claim 1, wherein the cooling device comprises a heat exchanger which is thermally connected to the adsorber and which is fluidically connected to a discharge gas line for evaporated cryogenic medium from the cold source.

3. The device as claimed in claim 2, wherein the adsorber is arranged in a vacuum chamber that is fluidically connected to the vacuum container.

4. The device as claimed in claim 3, wherein the fluidic connection between the vacuum chamber and the vacuum container can be closed.

5. The device as claimed in claim 1, wherein liquid nitrogen or a liquefied noble gas is used as the cryogenic liquefied gas in the cold source.

6. The device as claimed in claim 1, wherein the rotor has a shaft and a flywheel mass mounted thereon.

7. The device as claimed in claim 1, wherein the adsorber is arranged in a vacuum chamber that is fluidically connected to the vacuum container.

8. The device as claimed in claim 7, wherein the fluidic connection between the vacuum chamber and the vacuum container can be closed.

9. The device as claimed in claim 2, wherein liquid nitrogen or a liquefied noble gas is used as the cryogenic liquefied gas in the cold source.

10. The device as claimed in claim 3, wherein liquid nitrogen or a liquefied noble gas is used as the cryogenic liquefied gas in the cold source.

11. The device as claimed in claim 4, wherein liquid nitrogen or a liquefied noble gas is used as the cryogenic liquefied gas in the cold source.

12. The device as claimed in claim 2, wherein the rotor has a shaft and a flywheel mass mounted thereon.

13. The device as claimed in claim 3, wherein the rotor has a shaft and a flywheel mass mounted thereon.

14. The device as claimed in claim 4, wherein the rotor has a shaft and a flywheel mass mounted thereon.

15. The device as claimed in claim 5, wherein the rotor has a shaft and a flywheel mass mounted thereon.

Description

[0015] There follows a more detailed description, with reference to the drawing, of an exemplary embodiment of the invention.

[0016] The single drawing (FIG. 1) shows a flywheel energy store according to the invention.

[0017] The machine shown in the drawing, in the exemplary embodiment a flywheel energy store 1, comprises a flywheel mass 3 which is accommodated in a vacuum container 2 and is secured to a vertical shaft 4. The lower end of the shaft 4 is mounted contactlessly in a superconducting bearing 5 and, for that purpose, is equipped with a magnetic rotor unit 6. The superconducting bearing 5 comprises a stator 7 in which are arranged superconducting coils (not shown here) for generating a magnetic field suitable for contactless mounting of the shaft 4. A cooling unit 8, which is cooled using a cryogenic medium, extends radially around the stator 7. In the exemplary embodiment shown here, in which the coils of the stator 7 consist of a high-temperature superconducting material, the cryogenic medium is in particular liquid nitrogen; if, by contrast, the coils are made of a conventional superconductor, the cryogenic medium used is preferably liquid helium. The cooling unit 8 comprises a reservoir 9 for the cryogenic medium which is in thermal contact with the superconducting coils of the stator 7. The term “reservoir” is to be understood here in a broad sense and can in particular encompass a container filled with coolant or a line conveying coolant. A coolant supply line 11 that is fluidically connected to the reservoir 9 serves for supplying liquid cryogenic medium; a gas discharge line 12 which, during proper operation of the flywheel energy store 1, is fluidically connected to a gas phase in the reservoir 9 serves for discharging evaporated gaseous medium. The flywheel energy store 1 also comprises a motor/generator 13 with a static stator 14 and a rotor 15 which is arranged on the shaft 4 and serves for introducing or extracting energy into or from the flywheel energy store 1. Below the motor/generator 13 there is arranged a magnetic bearing 17 with a rotor 18 arranged on the shaft 4 and a stator 18 that interacts therewith. This magnetic bearing 17, which is preferably a conventional active magnetic bearing, serves merely as a guide and as a backup bearing in the event of the superconducting bearing 5 failing as a consequence of a fault.

[0018] In order to create and maintain, within the vacuum container 2, a vacuum that is adequate for long-term operation of the flywheel mass energy store 1, the vacuum container 2 is first evacuated, by means of a vacuum pump which is not shown here, to a pressure of for example 10.sup.−3 mbar. An adsorber 20, which is arranged within a thermally well-insulated vacuum chamber 21 connected to the vacuum container 2, serves to further improve the vacuum. The adsorber 20 comprises a body with an outer or inner surface area that is as large as possible. Molecules outgassing from parts of the apparatus arranged within the vacuum container 2, or entering the vacuum container 2 from outside, are caught by the adsorber 20 and are bound for the duration of use of the flywheel energy store 1. This permits a marked improvement of the vacuum in the vacuum container 2, to a value of for example 10.sup.−4 to 10.sup.−5 mbar and below. The adsorption effect is further improved by cooling. For this reason, the adsorber 20 is thermally connected to the gas discharge line 12 via a heat exchanger 22. The cooling makes use of the fact that, even after reaching a temperature below the critical temperature of the superconducting material used in each case in the stator 7, radiation and heat conduction mean that there is a continuous, albeit minor, input of heat into the superconducting bearing 5, which causes part of the coolant present in the reservoir 9 to evaporate. The cold content of the cryogenic coolant which evaporates and is discharged via the gas discharge line 12 is at least partially used in the heat exchanger 22 for cooling the adsorber 20. Thus, the adsorber 20 is cooled without having its own cooling system.

[0019] The vacuum chamber 21 and the vacuum container 2 are fluidically connected to one another via a connecting line 23 which, when required, can be closed off using a device not shown here, thus maintaining the vacuum in the vacuum container 2. Then, the vacuum chamber 21 is opened by means of an airlock (not shown here), and the adsorber 20 can be removed. It is thus possible to replace the adsorber 20 during operation of the flywheel mass energy store 1, should this be necessary in order to regenerate the relevant adsorber.

[0020] Furthermore, the adsorber 20 can also be arranged within the vacuum container 2, this dispensing with a separate vacuum chamber. However, in this case the vacuum container 2 would have to be vented in order to be able to replace the adsorber 20.

LIST OF REFERENCE SIGNS

[0021] 1. Flywheel energy store [0022] 2. Vacuum container [0023] 3. Flywheel mass [0024] 4. Shaft [0025] 5. Superconducting bearing [0026] 6. Rotor unit [0027] 7. Stator [0028] 8. Cooling unit [0029] 9. Reservoir [0030] 10. - [0031] 11. Coolant supply line [0032] 12. Gas discharge line [0033] 13. Motor/generator [0034] 14. Stator [0035] 15. Rotor [0036] 16. - [0037] 17. Magnetic bearing [0038] 18. Rotor [0039] 19. Stator [0040] 20. Adsorber [0041] 21. Vacuum chamber [0042] 22. Heat exchanger [0043] 23. Connecting line