EP1313951A1 - Vacuum pump - Google Patents

Vacuum pump

Info

Publication number
EP1313951A1
EP1313951A1 EP01965186A EP01965186A EP1313951A1 EP 1313951 A1 EP1313951 A1 EP 1313951A1 EP 01965186 A EP01965186 A EP 01965186A EP 01965186 A EP01965186 A EP 01965186A EP 1313951 A1 EP1313951 A1 EP 1313951A1
Authority
EP
European Patent Office
Prior art keywords
rotor
vacuum pump
magnet
axial
permanent magnet
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.)
Withdrawn
Application number
EP01965186A
Other languages
German (de)
French (fr)
Inventor
Christian Beyer
Heinrich Engländer
Josef Hodapp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Leybold GmbH
Original Assignee
Leybold Vakuum GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Leybold Vakuum GmbH filed Critical Leybold Vakuum GmbH
Publication of EP1313951A1 publication Critical patent/EP1313951A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
    • F04D29/056—Bearings
    • F04D29/058—Bearings magnetic; electromagnetic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F04D19/048—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps comprising magnetic bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
    • F04D29/051—Axial thrust balancing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/047—Details of housings; Mounting of active magnetic bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0474—Active magnetic bearings for rotary movement
    • F16C32/0476—Active magnetic bearings for rotary movement with active support of one degree of freedom, e.g. axial magnetic bearings
    • F16C32/0478—Active magnetic bearings for rotary movement with active support of one degree of freedom, e.g. axial magnetic bearings with permanent magnets to support radial load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2360/00—Engines or pumps
    • F16C2360/44—Centrifugal pumps
    • F16C2360/45—Turbo-molecular pumps

Definitions

  • the invention relates to a vacuum pump with a stator on which a rotor with at least one radial magnetic bearing and one axial magnetic bearing is mounted without contact.
  • Magnetic bearings are often used to support the rotor in vacuum pumps. Magnetic bearings allow high rotor speeds and are lubricant-free, which prevents contamination of the vacuum side of the pump with lubricant.
  • a vacuum pump is known from DE 38 18 556, in which the radial bearings are each formed by permanent magnetic rings which are axially slightly offset from one another. Since the mutually repelling magnetic rings also repel each other in an axial direction due to the offset arrangement, the rotor is preloaded in an axial direction.
  • a large lifting magnet is arranged at one axial end of the rotor and has an attractive effect on a rotor disk. The solenoid is like this regulated that it holds the rotor in the axially preloaded position.
  • An axial bearing is known from EP 0 414 127, in which two rotor disks are axially magnetized, so that the stator-side magnetic coils, depending on the direction of the current flowing through them, can act on the rotor in both axial directions.
  • the rotor-side magnetic disks have an attractive effect on the yoke iron of the magnetic coil, so that considerable axial attractive forces occur in both axial directions, which pull the rotor out of its axial central position and must be compensated for by the magnetic coils.
  • the object of the invention is to improve the axial magnetic bearing of a vacuum pump.
  • a permanently axially magnetized compensation magnet is provided on the stator, which compensates for the force effect of the magnetic field of the rotor permanent magnet on the yoke.
  • the compensation magnet is arranged in opposite polarity to the rotor permanent magnet, so that the rotor permanent magnet and the compensation magnet repel each other.
  • the compensation magnet can be arranged directly opposite the rotor permanent magnet separated by an air gap, but can also be arranged elsewhere in the course of the yoke iron.
  • the compensation magnet approximately compensates for the axial attractive forces between the rotor permanent magnet and the stator yoke. This will an axial preload in the axial magnetic bearing is avoided.
  • the rotor With the magnetic coil, the rotor can therefore be held in a tension-free middle position.
  • smaller solenoids can be used to safely control the axial center position of the rotor. Because of the lower control forces to be applied to the solenoid, the heat generated by the solenoid is also considerably reduced.
  • the axial magnetic bearing is designed in a ring shape, the magnetic coil, the yoke, the permanent rotor magnet and the compensation magnet being arranged in a ring around the motor. Since the axial magnetic bearing is not arranged on one of the end faces of the rotor, but around the rotor, a vacuum pump with a short overall length is realized.
  • a plurality of magnetic coils with segment-like yokes are provided, which are arranged around the rotor in a ring. Furthermore, a plurality of distance sensors can be provided over the circumference for detecting the rotor position and connected to a control device which controls the magnetic coils to compensate for tilting movements of the rotor. In this way, tilting movements of the rotor can be compensated for. Due to the possibility of avoiding tilting movements of the rotor by appropriate control of the axial bearing magnet coils, only permanent magnets can be used for the radial bearing or bearings, which do not permit any regulation of the bearing forces.
  • the stator has an eddy current damping disk made of electrically conductive material, which is arranged axially between the permanent rotor magnet and the yoke.
  • the eddy current damping disc dampens radial movements of the rotor by means of the eddy currents induced in the damping disc during radial rotor movements. In this way, effective radial damping is realized, which can be provided as an alternative or in addition to the active damping of rotor tilting movements.
  • the axial bearing is preferably arranged approximately radially of the center of gravity of the rotor and between two radial bearings, which are each arranged axially of the rotor center of gravity.
  • the center of gravity of the rotor is located between the two radial bearings, while the axial bearing lies approximately in the transverse center of gravity.
  • the axial bearing is arranged in such a way that the axial magnetic bearings can produce a high torque to generate a corresponding rotor tilting moment.
  • the magnet coil is arranged radially on the outside or radially on the inside of the permanent magnets.
  • the magnet coil and the permanent magnets are arranged approximately in a transverse plane. In this way, the overall length of the vacuum pump is kept small.
  • the yoke is preferably inclined to the axial and / or radially offset to the rotor permanent magnet together with the compensation magnet.
  • One end of the yoke iron is preferably arranged axially and the other end of the yoke iron is arranged radially of the rotor permanent magnet.
  • the arrangement of a free yoke iron end radially on the outside or inside of the rotor permanent magnet results in a non-nested arrangement of the parts of the axial magnetic bearing.
  • the complete rotor can be axially inserted into or removed from the stator from one side. This enables simple assembly of the rotor in the stator.
  • the rotor permanent magnet and the compensation magnet are arranged axially on the outside of the magnet coil, the rotor permanent magnet and the compensation magnet can be made relatively large, so that large magnetic forces can be generated. This improves the axial mounting as well as the stabilization against tilting movements of the rotor.
  • the axial magnetic bearing is designed as an active magnetic bearing
  • the radial bearings are designed as passive magnetic bearings.
  • FIG. 1 shows a first embodiment of a vacuum pump according to the invention in longitudinal section
  • FIG. 2 shows a second embodiment of a vacuum pump according to the invention with an axial bearing with three magnetic coils
  • FIG. 3 shows the three magnetic coils with associated yokes of the axial magnetic bearing of the vacuum pump of FIG. 2,
  • Fig. 4 shows a third embodiment of a vacuum pump in which the rotor permanent magnet and the compensation magnet are arranged radially outside of the magnet coil, and
  • Fig. 5 shows a fourth embodiment of a vacuum pump according to the invention with the radially inclined magnetic gap surfaces.
  • FIGs. 1-5 each show vacuum pumps 10, which are turbomolecular vacuum pumps. Turbomolecular pumps work at high speeds of up to 80,000 revolutions per minute. Because of the high speeds and the high reliability, contactless magnetic bearings have proven useful for mounting the rotor 12 in the stator 14.
  • two passive radial magnetic bearings 16, 18 are provided, which are arranged axially spaced from the center of gravity 20 of the rotor 12 at the respective longitudinal ends of the rotor.
  • the rotor center of gravity 20 lies approximately in the middle between the two radial bearings 16, 18.
  • Both Radial magnetic bearings 16, 18 are each formed from a cylindrical concentric inner sleeve 24 and outer sleeve 22, both of which are magnetized in the axial direction and are arranged in poles with respect to one another such that they radially repel each other.
  • Each inner and outer sleeve 24, 22 consists of a package of a plurality of magnetic rings which are axially joined together.
  • the multiple magnetic rings of an outer or inner sleeve are axially separated from one another by spacers 26.
  • the outer sleeves 22 are fastened to the rotor 12 and rotate about the stator-side inner sleeves 24.
  • the two inner sleeves 24 and the two outer sleeves 22 of the two radial bearings 16, 18 are of identical design.
  • the inner sleeves 24 of the two radial bearings 16, 18 are axially adjustable by means of adjusting screws 27.
  • the two radial bearings 16, 18 bring about an unstable axial equilibrium position, i.e. the rotor 12 tends to move in one or the other axial direction.
  • catch bearing 28, 30 designed as a roller bearing.
  • the rotor 12 consists essentially of a compressor part 13 and a shaft 15.
  • An electric motor 32 is arranged axially between the compressor part 13 and the shaft radial bearing 18, by means of which the rotor 12 is driven without contact.
  • the electric motor 32 is a high-frequency motor.
  • An axial bearing 40 is arranged between the compressor part 13 and the motor 32.
  • the thrust bearing 40 is a magnetic bearing and has an annular magnetic coil 42 which generates a toroidal magnetic field and is surrounded by a yoke iron 44.
  • the yoke iron 44 consists of two rings 45, 46 in the shape of an L-section, which form a rectangular frame in cross-section, which is interrupted at the inner corner on the compressor side, that is to say open.
  • the yoke iron preferably consists of an iron composite material with a 5% plastic content.
  • An axially magnetized annular permanent magnet 50 is fastened axially opposite to the yoke iron 44 on the rotor compressor 13 and is held on the rotor compressor 13 by a sleeve 52.
  • the magnetic field generated by the magnet coil 42 has an attractive or repulsive effect on the rotor ring magnet 50 in the axial direction, depending on the polarization of the generated magnetic field, that is to say depending on the direction of current in the magnet coil 42.
  • a permanently axially magnetized annular compensating magnet 54 is fixed, which is polarized oppositely to the rotor-side magnet 50, so the rotor permanent magnet 50 and • ⁇ compensating magnet 54 that repel.
  • An active thrust bearing is implemented, which can act in both axial directions, i.e. both attracting and repelling.
  • an axial inductive distance sensor 60 is provided on the stator housing 58, which detects the exact axial position of the rotor 12 by means of an inductive distance measurement and transmits a corresponding measurement signal to a control device (not shown).
  • the control device controls a corresponding control current to the magnet coil 42 in order to correct the axial position of the rotor 12 and to hold the rotor 12 in its central position.
  • the stator has an eddy current damping disk 62 made of an electrically highly conductive material, for example made of copper.
  • the damping disk 62 is thus arranged axially between the rotor ring magnet 50 and the stator-side compensation magnet 54.
  • electrical eddy currents are induced in the damping disk 62 by the rotor ring magnet 50.
  • the mecha- African energy of the rotor 12 is inductively transferred to the damping disk 62 and converted there into heat. In this way, vibrations and vibrations of the rotor 12 are effectively damped.
  • the magnet coil 42 is insulated from the vacuum part of the vacuum pump 10 by the insulation ring 48.
  • the electrical lines of the magnetic coil 42 therefore always run outside the vacuum range of the vacuum pump 10, so that no sealing problems occur.
  • the axial bearing 140 of the vacuum pump 110 of FIG. 2 is not one, but three magnetic coils 141, 142, 143 and the like Yoke iron inner ring sections 146 1 # 146 2 , 146 3 and corresponding yoke iron outer ring sections 145 1 -145 3 are formed, as can also be seen in FIG. 3. Between the ring sections 146 x -146 3 segments 147 made of non-magnetic material are arranged, which magnetically separate the yoke iron ring sections 146 1 -146 3 from one another.
  • three distance sensors 160 are provided, which determine the axial distance of the rotor 12 from the stator 12 approximately in the transverse plane of the axial bearing 140.
  • the rotor position can be detected three-dimensionally by the three axial distance sensors 160, so that not only axial deviations from the central position but also tilting movements of the rotor 12 can be detected. Tilting movements or tilting vibrations of the rotor 12 can be compensated for by the magnet coils 141-143 which can be controlled separately by a control device.
  • a vacuum pump 210 shown in FIG.
  • the magnet coils 241-243 are arranged radially inside and the rotor ring magnet 250, the stator compensation magnet 254 and the damping disk 262 are arranged radially outside of the magnet coils 241-243. This enables larger permanent magnets, which generate a greater torque on the rotor and thus a greater stabilizing effect. The load capacity of the thrust bearing is increased by the larger permanent magnets.
  • the rotor permanent magnet 350, the stator compensation magnet 354 and the damping disk 362 and the gap formed between the damping disk 362 and the rotor permanent magnet 350 are not exactly in the transverse plane, but in arranged at an angle of approximately 15 ° to it.
  • the direction of magnetization of the magnets 350, 354 is also inclined at 15 ° to the transverse plane.
  • the magnetic forces transmitted between the stator 314 and the rotor 312 are thereby increased and have both an axial and a smaller radial component.
  • both the axial position of the rotor 312 in the stator 314 and the radial position of the rotor 312 in the stator 314 can be regulated by suitable regulation of the magnetic coils 141-143. This allows radial breakouts and vibrations of the rotor to be reduced to a minimum.
  • the rotor Due to the compensation of the attractive forces between the rotor permanent magnet and the yoke by a compensation magnet, the rotor is free of pre-tension in its central position. Thereby the center position of the rotor can be regulated with relatively small magnet coil currents. This enables small magnetic coils, causes less heat to be generated and reduces the power consumption of the thrust bearing.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)

Abstract

The vacuum pump (10) comprises a stator (14) in which a rotor (12) with radial magnetic bearings (16,19) and with an axial magnetic bearing (40) is mounted in a contactless manner. The axial magnetic bearing (40) produces an axial magnetic field by means of a magnet coil (40) with a yoke iron (44) on the stator (14).An axially magnetized permanent magnet (50) is provided on the rotor (12), located approximately axially opposite the yoke iron (44). A permanently axially magnetized compensating magnet (54) is provided on the stator (14) and arranged axially opposite the permanent magnet of the rotor (50) and polarized in the opposite direction, whereby the permanent magnet (50) of the rotor and the compensating magnet (54) repel each other. In a centre position, the rotor is bias-free by compensating the forces of attraction between the permanent magnet of the rotor and the yoke iron. As a result, the centre position of the rotor can be adjusted with relatively small magnet coil flows. This results in small magnet coils, produces less heat and reduces the required power of the axial bearing.

Description

Vakuumpumpβ Vakuumpumpβ
Die Erfindung bezieht sich auf eine Vakuumpumpe mit einem Stator, an dem ein Rotor mit mindestens einem Radial-Magnet- lager und einem Axial-Magnetlager berührungslos gelagert ist.The invention relates to a vacuum pump with a stator on which a rotor with at least one radial magnetic bearing and one axial magnetic bearing is mounted without contact.
Bei Vakuumpumpen werden zur Lagerung des Rotors häufig Magnet- lager verwendet . Magnetlager lassen hohe Rotor-Drehzahlen zu und sind schmiermittelfrei, wodurch eine Verunreinigung der Vakuumseite der Pumpe mit Schmiermittel ausgeschlossen ist. Aus DE 38 18 556 ist eine Vakuumpumpe bekannt, bei der die Radial- Lager jeweils von zueinander axial geringfügig versetzt angeordneten Permanent-Magnetringen gebildet werden. Da die sich gegenseitig abstoßenden Magnetringe durch die versetzte Anordnung sich auch in einer axialen Richtung abstoßen, ist der Rotor in einer axialen Richtung vorgespannt. An einem axialen Ende des Rotors ist ein großer Hubmagnet angeordnet, der anziehend auf eine Rotorscheibe wirkt. Der Hubmagnet ist derart geregelt, dass er den Rotor in der axial vorgespannten Position hält . Der Hubmagnet muss dabei stets die axiale Vorspannung kompensieren. Aus EP 0 414 127 ist ein Axiallager bekannt, bei dem zwei Rotorscheiben axial magnetisiert sind, so dass die statorseitigen Magnetspulen, je nach Richtung des sie durchfließenden Stromes, in beiden axialen Richtungen auf den Rotor wirken können. Die rotorseitigen Magnetscheiben wirken anziehend auf das Jocheisen der Magnetspule, so dass in beiden axialen Richtungen erhebliche axiale Anziehungskräfte auftreten, die den Rotor aus seiner axialen Mittellage ziehen und durch die Magnetspulen ausgeglichen werden müssen.Magnetic bearings are often used to support the rotor in vacuum pumps. Magnetic bearings allow high rotor speeds and are lubricant-free, which prevents contamination of the vacuum side of the pump with lubricant. A vacuum pump is known from DE 38 18 556, in which the radial bearings are each formed by permanent magnetic rings which are axially slightly offset from one another. Since the mutually repelling magnetic rings also repel each other in an axial direction due to the offset arrangement, the rotor is preloaded in an axial direction. A large lifting magnet is arranged at one axial end of the rotor and has an attractive effect on a rotor disk. The solenoid is like this regulated that it holds the rotor in the axially preloaded position. The solenoid must always compensate for the axial preload. An axial bearing is known from EP 0 414 127, in which two rotor disks are axially magnetized, so that the stator-side magnetic coils, depending on the direction of the current flowing through them, can act on the rotor in both axial directions. The rotor-side magnetic disks have an attractive effect on the yoke iron of the magnetic coil, so that considerable axial attractive forces occur in both axial directions, which pull the rotor out of its axial central position and must be compensated for by the magnetic coils.
Aufgabe der Erfindung ist es, das Axial-Magnetlager einer Vakuumpumpe zu verbessern.The object of the invention is to improve the axial magnetic bearing of a vacuum pump.
Diese Aufgabe wird erfindungsgemäß mit den Merkmalen des Anspruchs 1 gelöst .This object is achieved with the features of claim 1.
Bei dem erfindungsgemäßen Vakuumpumpen-Axiallager ist an dem Stator ein permanent axial magnetisierter Kompensationsmagnet vorgesehen, der die Kraftwirkung des Magnetfeldes des Rotor- Permanentmagneten auf das Jocheisen kompensiert. Der Kompensationsmagnet ist gegensinnig polarisiert zu dem Rotor- Permanentmagneten angeordnet, so dass sich der Rotor- Permanentmagnet und der Kompensationsmagnet gegenseitig abstoßen. Der Kompensationsmagnet kann dem Rotor-Permanentmagneten durch einen Luftspalt getrennt direkt gegenüberliegend angeordnet sein, kann jedoch auch im Verlauf des Jocheisens an anderer Stelle angeordnet sein. Der Kompensationsmagnet kompensiert annähernd die axialen Anziehungskräfte zwischen dem Rotor-Permanentmagneten und dem Stator-Jocheisen. Dadurch wird eine axiale Vorspannung in dem Axial-Magnetlager vermieden. Mit der Magnetspule kann der Rotor deshalb in einer vorspannungsfreien Mittellage gehalten werden. Durch den Wegfall der axialen Vorspannung können zur sicheren Regelung der axialen Mittellage des Rotors kleinere Magnetspulen verwendet werden. Wegen der geringeren aufzubringenden Regelungskräfte der Magnetspule wird auch die Wärmeentwicklung durch die Magnetspule erheblich reduziert.In the vacuum pump axial bearing according to the invention, a permanently axially magnetized compensation magnet is provided on the stator, which compensates for the force effect of the magnetic field of the rotor permanent magnet on the yoke. The compensation magnet is arranged in opposite polarity to the rotor permanent magnet, so that the rotor permanent magnet and the compensation magnet repel each other. The compensation magnet can be arranged directly opposite the rotor permanent magnet separated by an air gap, but can also be arranged elsewhere in the course of the yoke iron. The compensation magnet approximately compensates for the axial attractive forces between the rotor permanent magnet and the stator yoke. This will an axial preload in the axial magnetic bearing is avoided. With the magnetic coil, the rotor can therefore be held in a tension-free middle position. By eliminating the axial preload, smaller solenoids can be used to safely control the axial center position of the rotor. Because of the lower control forces to be applied to the solenoid, the heat generated by the solenoid is also considerably reduced.
Gemäß einer bevorzugten Ausgestaltung ist das Axial-Magnetlager ringförmig ausgebildet, wobei die Magnetspule, das Jocheisen, der Rotor-Permanentmagnet und der Kompensationsmagnet ringartig um den Motor herum angeordnet sind. Da das Axial-Magnetlager nicht an einer der Stirnseiten des Rotors, sondern um den Rotor herum angeordnet ist, wird eine Vakuumpumpe mit kurzer Baulänge realisiert .According to a preferred embodiment, the axial magnetic bearing is designed in a ring shape, the magnetic coil, the yoke, the permanent rotor magnet and the compensation magnet being arranged in a ring around the motor. Since the axial magnetic bearing is not arranged on one of the end faces of the rotor, but around the rotor, a vacuum pump with a short overall length is realized.
Gemäß einer bevorzugten Ausgestaltung sind mehrere Magnetspulen mit segmentartigen Jocheisen vorgesehen, die zu einem Ring zusammengesetzt um den Rotor herum angeordnet sind. Ferner können über den Umfang mehrere Abstandssensoren zur Erfassung der Rotorposition vorgesehen und mit einer Steuervorrichtung verbunden sein, die die Magnetspulen zur Kompensation von Kippbewegungen des Rotors ansteuert. Auf diese Weise können Kippbewegungen des Rotors ausgeglichen werden. Durch die Möglichkeit, Kippbewegungen des Rotores durch entsprechende Steuerung der Axiallager-Magnetspulen zu vermeiden, können ' für das bzw. die Radiallager ausschließlich Permanentmagnete verwendet werden, die keine Regelung der Lagerkräfte zulassen. Gemäß einer bevorzugten Ausgestaltung weist der Stator eine Wirbelstrom-Dämpfungsscheibe aus elektrisch leitendem Material auf, die axial zwischen dem Rotor-Permanentmagneten und dem Jocheisen angeordnet ist. Die Wirbelstrom-DämpfungsScheibe bewirkt eine Dämpfung radialer Bewegungen des Rotors durch die bei radialen Rotorbewegungen in der Dämpfungsscheibe induzierten Wirbelstrδme. Auf diese Weise wird eine wirkungsvolle radiale Dämpfung realisiert, die alternativ oder ergänzend zur aktiven Dämpfung von Rotor-Kippbewegungen vorgesehen werden kann.According to a preferred embodiment, a plurality of magnetic coils with segment-like yokes are provided, which are arranged around the rotor in a ring. Furthermore, a plurality of distance sensors can be provided over the circumference for detecting the rotor position and connected to a control device which controls the magnetic coils to compensate for tilting movements of the rotor. In this way, tilting movements of the rotor can be compensated for. Due to the possibility of avoiding tilting movements of the rotor by appropriate control of the axial bearing magnet coils, only permanent magnets can be used for the radial bearing or bearings, which do not permit any regulation of the bearing forces. According to a preferred embodiment, the stator has an eddy current damping disk made of electrically conductive material, which is arranged axially between the permanent rotor magnet and the yoke. The eddy current damping disc dampens radial movements of the rotor by means of the eddy currents induced in the damping disc during radial rotor movements. In this way, effective radial damping is realized, which can be provided as an alternative or in addition to the active damping of rotor tilting movements.
Vorzugsweise ist das Axiallager annähernd radial des Schwerpunktes des Rotors und zwischen zwei Radiallagern angeordnet, die jeweils axial des Rotorschwerpunktes angeordnet sind. Der Schwerpunkt des Rotors befindet sich zwischen den beiden Radiallagern, während das Axiallager ungefähr in der Schwerpunktquerebene liegt. Bei dieser Anordnung wird eine hohe Kippstabilität des Rotors realisiert. Gleichzeitig ist das Axiallager so angeordnet, dass die Axial-Magnetlager ein hohes Drehmoment zur Erzeugung eines entsprechenden Rotor-Kippmomentes bewirken können.The axial bearing is preferably arranged approximately radially of the center of gravity of the rotor and between two radial bearings, which are each arranged axially of the rotor center of gravity. The center of gravity of the rotor is located between the two radial bearings, while the axial bearing lies approximately in the transverse center of gravity. With this arrangement, a high tilt stability of the rotor is realized. At the same time, the axial bearing is arranged in such a way that the axial magnetic bearings can produce a high torque to generate a corresponding rotor tilting moment.
Gemäß einer bevorzugten Ausgestaltung ist die Magnetspule radial außen oder radial innen der Permanentmagnete angeordnet . Die Anordnung der Magnetspule und der Permanentmagnete erfolgt ungefähr in einer Querebene. Auf diese Weise wird die Baulänge der Vakuumpumpe klein gehalten.According to a preferred embodiment, the magnet coil is arranged radially on the outside or radially on the inside of the permanent magnets. The magnet coil and the permanent magnets are arranged approximately in a transverse plane. In this way, the overall length of the vacuum pump is kept small.
Vorzugsweise ist das Jocheise zusammen mit dem Kompensations- magneten zur Axialen geneigt und/oder radial versetzt zu dem Rotor-Permanentmagneten angeordnet. Auf diese Weise wird der Luftspalt zwischen Jocheisen und Kompensationsmagneten einerseits und Rotor-Permanentmagneten andererseits zur Querebene geneigt und in seiner Fläche vergrößert, so dass die Verwendung größerer Magneten ermöglicht und im Ergebnis die Realisierung größerer Magnetkräfte ermöglicht wird.The yoke is preferably inclined to the axial and / or radially offset to the rotor permanent magnet together with the compensation magnet. In this way the Air gap between yoke and compensation magnet on the one hand and rotor permanent magnet on the other hand inclined to the transverse plane and enlarged in area, so that the use of larger magnets is possible and, as a result, the realization of larger magnetic forces is made possible.
Vorzugsweise ist ein Ende des Jocheisens axial und das andere Ende des Jocheisens radial des Rotor-Permanentmagneten angeordnet . Durch die Anordnung eines freien Jocheisenendes radial außen oder innen des Rotor-Permanentmagneten wird eine unverschachtelte Anordnung der Teile des Axial-Magnetlagers realisiert. Der komplette Rotor kann von einer Seite aus axial in den Stator eingesetzt bzw. aus diesem herausgenommen werden. Dadurch wird eine einfache Montage des Rotors in dem Stator ermöglicht .One end of the yoke iron is preferably arranged axially and the other end of the yoke iron is arranged radially of the rotor permanent magnet. The arrangement of a free yoke iron end radially on the outside or inside of the rotor permanent magnet results in a non-nested arrangement of the parts of the axial magnetic bearing. The complete rotor can be axially inserted into or removed from the stator from one side. This enables simple assembly of the rotor in the stator.
Wenn der Rotor-Permanentmagnet und der Kompensationsmagnet axial außen der Magnetspule angeordnet sind, lassen sich Rotor- Permanentmagnet und Kompensationsmagnet relativ groß ausbilden, so dass große Magnetkräfte erzeugt werden können. Dadurch wird die axiale Lagerung, wie auch die Stabilisierung gegen Kippbewegungen des Rotors verbessert .If the rotor permanent magnet and the compensation magnet are arranged axially on the outside of the magnet coil, the rotor permanent magnet and the compensation magnet can be made relatively large, so that large magnetic forces can be generated. This improves the axial mounting as well as the stabilization against tilting movements of the rotor.
Während das Axial-Magnetlager als aktives Magnetlager ausgebildet ist, sind die Radiallager als passive Magnetlager ausgebildet.While the axial magnetic bearing is designed as an active magnetic bearing, the radial bearings are designed as passive magnetic bearings.
Im folgenden werden unter Bezugnahme auf die Zeichnungen mehrere Ausführungsbeispiele der Erfindung näher erläutert. Es zeigen :Several exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Show it :
Fig. 1 eine erste Ausführungsform einer erfindungsgemäßen Vakuumpumpe im Längsschnitt,1 shows a first embodiment of a vacuum pump according to the invention in longitudinal section,
Fig. 2 eine zweite Ausführungsform einer erfindungsgemäßen Vakuumpumpe mit einem Axiallager mit drei Magnetspulen,2 shows a second embodiment of a vacuum pump according to the invention with an axial bearing with three magnetic coils,
Fig. 3 die drei Magnetspulen mit zugehörigen Jocheisen des Axial-Magnetlagers der Vakuumpumpe der Fig. 2,3 shows the three magnetic coils with associated yokes of the axial magnetic bearing of the vacuum pump of FIG. 2,
Fig. 4 eine dritte Ausführungsform einer Vakuumpumpe, bei der der Rotor-Permanentmagnet und der Kompensationsmagnet radial außen der Magnetspule angeordnet sind, undFig. 4 shows a third embodiment of a vacuum pump in which the rotor permanent magnet and the compensation magnet are arranged radially outside of the magnet coil, and
Fig. 5 ein viertes Ausführungsbeispiel einer erfindungsgemäßen Vakuumpumpe mit zur radialen geneigten Magnetspaltflächen.Fig. 5 shows a fourth embodiment of a vacuum pump according to the invention with the radially inclined magnetic gap surfaces.
In den Fign. 1-5 sind jeweils Vakuumpumpen 10 dargestellt, bei denen es sich um Turbomolekular-Vakuumpumpen handelt. Turbo- molekular-Pumpen arbeiten mit hohen Drehzahlen von bis zu 80.000 Umdrehungen pro Minute. Wegen der hohen Drehzahlen und der hohen Zuverlässigkeit haben sich zur Lagerung des Rotors 12 in dem Stator 14 berührungslose Magnetlager bewährt.In Figs. 1-5 each show vacuum pumps 10, which are turbomolecular vacuum pumps. Turbomolecular pumps work at high speeds of up to 80,000 revolutions per minute. Because of the high speeds and the high reliability, contactless magnetic bearings have proven useful for mounting the rotor 12 in the stator 14.
Bei den Vakuumpumpen der Fign. 1-5 sind jeweils zwei passive Radial-Magnetlager 16,18 vorgesehen, die axial beabstandet zu dem Schwerpunkt 20 des Rotors 12 an den jeweiligen Rotor- Längsenden angeordnet sind. Der Rotor-Schwerpunkt 20 liegt ungefähr in der Mitte zwischen beiden Radiallagern 16,18. Beide Radial-Magnetlager 16,18 werden jeweils aus einer zylinder- förmigen konzentrischen Innenhülse 24 und Außenhülse 22 gebildet, die beide in axialer Richtung magnetisiert und derart zueinander gepolt angeordnet sind, dass sie sich radial abstoßen. Jede Innen- und Außenhülse 24, 22 besteht aus einem Paket von mehreren Magnetringen, die axial aneinander gefügt sind. Die mehreren Magnetringe einer Außen- bzw. Innenhülse sind axial durch Distanzscheiben 26 voneinander getrennt. Die Außenhülsen 22 sind an dem Rotor 12 befestigt und rotieren um die statorseitigen Innenhülsen 24. Die beiden Innenhülsen 24 und die beiden Außenhülsen 22 der beiden Radiallager 16, 18 sind identisch ausgebildet.With the vacuum pumps of FIGS. 1-5, two passive radial magnetic bearings 16, 18 are provided, which are arranged axially spaced from the center of gravity 20 of the rotor 12 at the respective longitudinal ends of the rotor. The rotor center of gravity 20 lies approximately in the middle between the two radial bearings 16, 18. Both Radial magnetic bearings 16, 18 are each formed from a cylindrical concentric inner sleeve 24 and outer sleeve 22, both of which are magnetized in the axial direction and are arranged in poles with respect to one another such that they radially repel each other. Each inner and outer sleeve 24, 22 consists of a package of a plurality of magnetic rings which are axially joined together. The multiple magnetic rings of an outer or inner sleeve are axially separated from one another by spacers 26. The outer sleeves 22 are fastened to the rotor 12 and rotate about the stator-side inner sleeves 24. The two inner sleeves 24 and the two outer sleeves 22 of the two radial bearings 16, 18 are of identical design.
Die Innenhülsen 24 der beiden Radiallager 16,18 sind durch Justierschrauben 27 axial verstellbar.The inner sleeves 24 of the two radial bearings 16, 18 are axially adjustable by means of adjusting screws 27.
Die beiden Radiallager 16,18 bewirken eine labile axiale Gleichgewichtslage, d.h. der Rotor 12 neigt dazu, in die eine oder andere axiale Richtung auszuweichen.The two radial bearings 16, 18 bring about an unstable axial equilibrium position, i.e. the rotor 12 tends to move in one or the other axial direction.
An beiden axialen Enden des Rotors 12 ist jeweils ein als Wälzlager ausgebildetes Fanglager 28,30 vorgesehen.At both axial ends of the rotor 12 there is a catch bearing 28, 30 designed as a roller bearing.
Der Rotor 12 besteht im wesentlichen aus einem Verdichterteil 13 und einer Welle 15. Axial zwischen dem Verdichterteil 13 und dem Wellen-Radiallager 18 ist ein Elektromotor 32 angeordnet, durch den der Rotor 12 berührungslos angetrieben wird. Der Elektromotor 32. ist ein Hochfrequenzmotor.The rotor 12 consists essentially of a compressor part 13 and a shaft 15. An electric motor 32 is arranged axially between the compressor part 13 and the shaft radial bearing 18, by means of which the rotor 12 is driven without contact. The electric motor 32 is a high-frequency motor.
Zwischen dem Verdichterteil 13 und dem Motor 32 ist ein Axial- lager 40 angeordnet. Das Axiallager 40 ist ein Magnetlager und weist eine ein torusformiges Magnetfeld erzeugende ringförmige Magnetspule 42 auf, die von einem Jocheisen 44 umgeben ist. Das Jocheisen 44 besteht aus zwei im Querschnitt L-förmigen Ringen 45,46, die einen im Querschnitt rechteckigen Rahmen bilden, der an der inneren verdichterseitigen Ecke unterbrochen, also offen ist. Das Jocheisen besteht vorzugsweise aus einem Eisen- Verbund-Werkstoff mit einem 5%-igen Kunststoffanteil . Dadurch wird die Induktion von Wirbelströmen geringgehalten und die Regelung des Axiallagers 40 beschleunigt. Ein zylindrischer Dichtungsring 48 schließt die Magnetspule gasdicht ab.An axial bearing 40 is arranged between the compressor part 13 and the motor 32. The thrust bearing 40 is a magnetic bearing and has an annular magnetic coil 42 which generates a toroidal magnetic field and is surrounded by a yoke iron 44. The yoke iron 44 consists of two rings 45, 46 in the shape of an L-section, which form a rectangular frame in cross-section, which is interrupted at the inner corner on the compressor side, that is to say open. The yoke iron preferably consists of an iron composite material with a 5% plastic content. As a result, the induction of eddy currents is kept low and the regulation of the axial bearing 40 is accelerated. A cylindrical sealing ring 48 closes the solenoid gas-tight.
An dem Rotorverdichter 13 ist dem Jocheisen 44 axial gegenüberliegend ein axial magnetisierter ringförmiger Permanentmagnet 50 befestigt, der von einer Hülse 52 an dem Rotorverdichter 13 gehalten wird. Das von der Magnetspule 42 erzeugte Magnetfeld wirkt auf den Rotor-Ringmagneten 50 in axialer Richtung anziehend oder abstoßend, je nach Polarisierung des erzeugten Magnetfeldes, also je nach Stromrichtung in der Magnetspule 42.An axially magnetized annular permanent magnet 50 is fastened axially opposite to the yoke iron 44 on the rotor compressor 13 and is held on the rotor compressor 13 by a sleeve 52. The magnetic field generated by the magnet coil 42 has an attractive or repulsive effect on the rotor ring magnet 50 in the axial direction, depending on the polarization of the generated magnetic field, that is to say depending on the direction of current in the magnet coil 42.
An der axialen Stirnseite des inneren Jocheisen-Ringes 46 ist ein permanent axial magnetisierter ringförmiger Kompensations- magnet 54 befestigt, der zu dem rotorseitigen Magneten 50 gegensinnig polarisiert ist, so dass sich der Rotor-Permanentmagnet 50 und • der ■ Kompensationsmagnet 54 abstoßen. Auf diese Weise werden die von dem Rotor-Ringmagneten 50 und dem inneren Jocheisenring 46 erzeugten magnetischen Anziehungskräfte annähernd durch entsprechende Abstoßungskräfte zwischen dem Rotor-Ringmagneten 50 und 'dem Kompensations-Ringmagneten 54 kompensiert . Es ist ein aktives Axiallager realisiert, das in beide axiale Richtungen wirken kann, also sowohl anziehend als auch abstoßend. Durch Vorsehen des Kompensationsmagneten 54 kann die Regelung um eine annähernd vorspannungsfreie axiale Mittellage herum erfolgen. Durch die Vorspannungsfreiheit sind zur Haltung der axialen Mittellage des Rotors 12 nur relativ kleine axiale Regelkräfte erforderlich. Hierdurch wird die Verwendung einer kleinen Magnetspule 42 ermöglicht. Durch die insgesamt verringerte erforderliche Regelleistung wird eine kleinere Magnetspule und Regelvorrichtung ermöglicht, und eine geringere Wärmeerzeugung durch die Magnetspule 42 erreicht .On the axial end side of the inner yoke iron ring 46, a permanently axially magnetized annular compensating magnet 54 is fixed, which is polarized oppositely to the rotor-side magnet 50, so the rotor permanent magnet 50 and • ■ compensating magnet 54 that repel. In this way, the magnetic attraction forces generated by the rotor ring magnet 50 and the inner yoke iron ring 46 are approximately compensated for by corresponding repulsive forces between the rotor ring magnet 50 and the compensation ring magnet 54. An active thrust bearing is implemented, which can act in both axial directions, i.e. both attracting and repelling. By providing the compensation magnet 54, the regulation can be carried out around an axially central position that is almost free of prestress. Due to the lack of prestressing, only relatively small axial control forces are required to maintain the axial central position of the rotor 12. This enables the use of a small magnetic coil 42. The overall reduced control power required enables a smaller solenoid and control device, and less heat is generated by the solenoid 42.
An dem axialen Ende der Rotorwelle 15 ist an dem Statorgehäuse 58 ein axialer induktiver Abstandssensor 60 vorgesehen, der die genaue axiale Lage des Rotors 12 durch eine induktive Abstands- messung feststellt und ein entsprechendes Messsignal an eine nicht dargestellte Steuervorrichtung überträgt . Die Steuervorrichtung steuert in Abhängigkeit von der ermittelten axialen Position, Geschwindigkeit und Beschleunigung des Rotors 12 einen entsprechenden Steuerstrom zu der Magnetspule 42, um die axiale Lage des Rotors 12 zu korrigieren, und den Rotor 12 in seiner Mittellage zu halten.At the axial end of the rotor shaft 15, an axial inductive distance sensor 60 is provided on the stator housing 58, which detects the exact axial position of the rotor 12 by means of an inductive distance measurement and transmits a corresponding measurement signal to a control device (not shown). Depending on the determined axial position, speed and acceleration of the rotor 12, the control device controls a corresponding control current to the magnet coil 42 in order to correct the axial position of the rotor 12 and to hold the rotor 12 in its central position.
Axial vor dem Kompensationsmagneten 54 weist der Stator eine Wirbelstrom-Dämpfungsscheibe 62 aus einem elektrisch gut leitendem Material, beispielsweise aus Kupfer, auf. Die Dämpfungsscheibe 62 ist also axial zwischen dem Rotor-Ringmagneten 50 und dem statorseitigen Kompensationsmagneten 54 angeordnet. Bei radialen Bewegungen bzw. Vibrationen des Rotors 12 werden durch den Rotor-Ringmagneten 50 in der Dämpfungsscheibe 62 elektrische Wirbelströme induziert. Dadurch wird die mecha- nische Energie des Rotors 12 induktiv auf die Dämpfungsscheibe 62 übertragen und dort in Wärme umgesetzt. Auf diese Weise werden Vibrationen und Schwingungen des Rotors 12 wirksam gedämpft .Axially in front of the compensation magnet 54, the stator has an eddy current damping disk 62 made of an electrically highly conductive material, for example made of copper. The damping disk 62 is thus arranged axially between the rotor ring magnet 50 and the stator-side compensation magnet 54. In the event of radial movements or vibrations of the rotor 12, electrical eddy currents are induced in the damping disk 62 by the rotor ring magnet 50. The mecha- African energy of the rotor 12 is inductively transferred to the damping disk 62 and converted there into heat. In this way, vibrations and vibrations of the rotor 12 are effectively damped.
Durch den Isolationsring 48 wird die Magnetspule 42 gegenüber dem Vakuumteil der Vakuumpumpe 10 isoliert. Die elektrischen Leitungen der Magnetspule 42 verlaufen also stets außerhalb des Vakuumbereiches der Vakuumpumpe 10, so dass keine Dichtungsprobleme auftreten.The magnet coil 42 is insulated from the vacuum part of the vacuum pump 10 by the insulation ring 48. The electrical lines of the magnetic coil 42 therefore always run outside the vacuum range of the vacuum pump 10, so that no sealing problems occur.
Bei der in der Fig. 2 dargestellten Vakuumpumpe 110 ist identisch mit der in Fig. 1 dargestellten Vakuumpumpe 10, bis auf das Axiallager 140. Das Axiallager 140 der Vakuumpumpe 110 der Fig. 2 wird nicht von einer, sondern von drei Magnetspulen 141,142,143 und entsprechenden Jocheisen-Innenring-Abschnitten 1461# 1462, 1463 und entsprechenden Jocheisen-Außenring-Abschnitten 1451-1453 gebildet, wie auch in Fig. 3 erkennbar ist. Zwischen den Ringabschnitten 146x-1463 sind Segmente 147 aus nicht magnetischem Material angeordnet, die die Jocheisen-Ringabschnitte 1461-1463 magnetisch voneinander trennen. Ferner sind drei Abstandssensoren' 160 vorgesehen, die ungefähr in der Querebene des Axiallagers 140 den axialen Abstand des Rotors 12 zum Stator 12 ermitteln. Durch die insgesamt drei axialen Abstandssensoren 160 kann die Rotorposition dreidimensional erfasst werden, so dass nicht nur axiale Abweichungen von der Mittellage, sondern auch Kippbewegungen des Rotors 12 erfasst werden können. Durch die separat durch eine Steuervorrichtung ansteuerbaren Magnetspulen 141-143 lassen sich Kippbewegungen bzw. Kippschwingungen des Rotors 12 kompensieren. Bei der in Fig. 4 dargestellten dritten Ausführungsform einer Vakuumpumpe 210 sind die Magnetspulen 241-243 radial innen und der Rotor-Ringmagnet 250, der Stator-Kompensationsmagnet 254 und die Dämpfungsscheibe 262 radial außen der Magnetspulen 241- 243 angeordnet. Hierdurch werden größere Permanentmagnete ermöglicht, die ein größeres Drehmoment auf den Rotor und damit eine größere stabilisierendere Wirkung erzeugen. Durch die größeren Permanentmagnete wird die Tragkraft des Axiallagers erhöht .2 is identical to the vacuum pump 10 shown in FIG. 1, except for the axial bearing 140. The axial bearing 140 of the vacuum pump 110 of FIG. 2 is not one, but three magnetic coils 141, 142, 143 and the like Yoke iron inner ring sections 146 1 # 146 2 , 146 3 and corresponding yoke iron outer ring sections 145 1 -145 3 are formed, as can also be seen in FIG. 3. Between the ring sections 146 x -146 3 segments 147 made of non-magnetic material are arranged, which magnetically separate the yoke iron ring sections 146 1 -146 3 from one another. Furthermore, three distance sensors 160 are provided, which determine the axial distance of the rotor 12 from the stator 12 approximately in the transverse plane of the axial bearing 140. The rotor position can be detected three-dimensionally by the three axial distance sensors 160, so that not only axial deviations from the central position but also tilting movements of the rotor 12 can be detected. Tilting movements or tilting vibrations of the rotor 12 can be compensated for by the magnet coils 141-143 which can be controlled separately by a control device. In the third embodiment of a vacuum pump 210 shown in FIG. 4, the magnet coils 241-243 are arranged radially inside and the rotor ring magnet 250, the stator compensation magnet 254 and the damping disk 262 are arranged radially outside of the magnet coils 241-243. This enables larger permanent magnets, which generate a greater torque on the rotor and thus a greater stabilizing effect. The load capacity of the thrust bearing is increased by the larger permanent magnets.
In der in Fig. 5 dargestellten vierten Ausführungsform einer Vakuumpumpe 310 ist der Rotor-Permanentmagnet 350, der Stator- Kompensationsmagnet 354 und die DämpfungsScheibe 362 und der zwischen der Dämpfungsscheibe 362 und dem Rotor-Permanentmagneten 350 gebildete Spalt nicht genau in der Querebene, sondern in einem Winkel von ungefähr 15° dazu geneigt angeordnet. Die Magnetisierungsrichtung der Magnete 350, 354 ist ebenfalls in 15° zur Querebene geneigt. Die zwischen dem Stator 314 und dem Rotor 312 übertragenen Magnetkräfte werden dadurch vergrößert, und weisen sowohl eine axiale als auch eine kleinere radiale Komponente auf. Auf diese Weise lassen sich durch eine geeignete Regelung der Magnetspulen 141-143 sowohl die axiale Lage des Rotors 312 in dem Stator 314 als auch die radiale Lage des Rotors 312 in dem Stator 314 regeln. Damit lassen sich radiale Ausbrüche und Schwingungen des Rotors auf ein Minimum reduzieren.In the fourth embodiment of a vacuum pump 310 shown in FIG. 5, the rotor permanent magnet 350, the stator compensation magnet 354 and the damping disk 362 and the gap formed between the damping disk 362 and the rotor permanent magnet 350 are not exactly in the transverse plane, but in arranged at an angle of approximately 15 ° to it. The direction of magnetization of the magnets 350, 354 is also inclined at 15 ° to the transverse plane. The magnetic forces transmitted between the stator 314 and the rotor 312 are thereby increased and have both an axial and a smaller radial component. In this way, both the axial position of the rotor 312 in the stator 314 and the radial position of the rotor 312 in the stator 314 can be regulated by suitable regulation of the magnetic coils 141-143. This allows radial breakouts and vibrations of the rotor to be reduced to a minimum.
Durch die Kompensation der Anziehungskräfte zwischen Rotor-Permanentmagneten und Jocheisen durch einen Kompensationsmagneten ist der Rotor in seiner Mittellage vorspannungsfrei. Dadurch kann die Mittellage des Rotors mit relativ kleinen Magnetspulströmen geregelt werden. Dies ermöglicht kleine Magnetspulen, bewirkt eine geringere Wärmeentwicklung und reduziert die erforderliche Leistungsaufnahme des Axiallagers. Due to the compensation of the attractive forces between the rotor permanent magnet and the yoke by a compensation magnet, the rotor is free of pre-tension in its central position. Thereby the center position of the rotor can be regulated with relatively small magnet coil currents. This enables small magnetic coils, causes less heat to be generated and reduces the power consumption of the thrust bearing.

Claims

PATENTANSPRUCHE PATENT CLAIMS
1. Vakuumpumpe mit einem Stator (14), in dem ein Rotor (12) mit einem Radial-Magnetlager (16,18) und einem Axial-Magnetlager (40) berührungslos gelagert ist, wobei1. Vacuum pump with a stator (14) in which a rotor (12) with a radial magnetic bearing (16, 18) and an axial magnetic bearing (40) is mounted without contact, wherein
das Axial-Magnetlager (40) an dem Stator (14) eine ein axiales Magnetfeld erzeugende Magnetspule (42) mit einem Jocheisen (44) , und an dem Rotor (12) einen axial magneti- sierten Permanentmagneten (50) aufweist, der dem Jocheisen (44) annähernd axial gegenüberliegt,the axial magnetic bearing (40) on the stator (14) has a magnetic coil (42) generating an axial magnetic field with a yoke iron (44), and on the rotor (12) has an axially magnetized permanent magnet (50) which is attached to the yoke iron (44) is approximately axially opposite,
d a d u r c h g e k e n n z e i c h n e t ,characterized ,
dass an dem Stator (14) ein permanent axial magnetisierter Kompensationsmagnet (54) vorgesehen ist, der das Magnetfeld des Rotor-Permanentmagneten (50) kompensiert.that a permanently axially magnetized compensation magnet (54) is provided on the stator (14), which compensates for the magnetic field of the rotor permanent magnet (50).
2. Vakuumpumpe nach Anspruch 1, dadurch gekennzeichnet, dass das Axial-Magnetlager (40) ringförmig ausgebildet ist, und die Magnetspule (42) , das Jocheisen (44) , der Rotor-Permanentmagnet (50) und der Kompensationsmagnet (54) ringartig um den Rotor (12) herum angeordnet sind.2. Vacuum pump according to claim 1, characterized in that the axial magnetic bearing (40) is ring-shaped, and the magnetic coil (42), the yoke (44), the rotor permanent magnet (50) and the compensation magnet (54) around like a ring the rotor (12) are arranged around.
3. Vakuumpumpe nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass mehrere Magnetspulen (141-143) mit Jocheisen (140) ringartig um den Rotor (112) herum angeordnet sind.3. Vacuum pump according to claim 1 or 2, characterized in that a plurality of magnetic coils (141-143) with yokes (140) are arranged in a ring around the rotor (112).
4. Vakuumpumpe nach einem der Ansprüche 1-3, dadurch gekennzeichnet, dass der Stator (14) eine Wirbelstrom-Dämpfungs- scheibe (62) aus elektrisch leitendem Material aufweist, die axial zwischen dem Rotor-Permanentmagneten (50) und dem Jocheisen (44) angeordnet ist.4. Vacuum pump according to one of claims 1-3, characterized in that the stator (14) has an eddy current damping disc (62) made of electrically conductive material, which is arranged axially between the rotor permanent magnet (50) and the yoke iron (44).
5. Vakuumpumpe nach Anspruch 3 oder 4, dadurch gekennzeichnet, dass mehrere Abstandssensoren (160) in einer einzigen Rotor-Querebene zur Erfassung der Rotorposition vorgesehen und mit einer Steuervorrichtung verbunden sind, die die Magnetspulen (141-143) zur Kompensation von Kippbewegungen des Rotors (112) ansteuert.5. Vacuum pump according to claim 3 or 4, characterized in that a plurality of distance sensors (160) are provided in a single transverse plane of the rotor for detecting the rotor position and are connected to a control device which the solenoid coils (141-143) for compensation of tilting movements of the rotor (112) controls.
6. Vakuumpumpe nach einem der Ansprüche 1-5, dadurch gekennzeichnet, dass ein freies Ende des Jocheisens (44) axial und das andere freie Ende des Jocheisens (44) radial des Rotor-Permanentmagneten (50) angeordnet ist.6. Vacuum pump according to one of claims 1-5, characterized in that a free end of the yoke iron (44) is arranged axially and the other free end of the yoke iron (44) is arranged radially of the rotor permanent magnet (50).
7. Vakuumpumpe nach einem der Ansprüche 1-6, dadurch gekennzeichnet, dass das Axiallager (40) annähernd radial des Schwerpunktes (20) des Rotors (12) und zwischen zwei Radiallagern (16,18) angeordnet ist, die jeweils axial beabstandet zu dem Rotor-Schwerpunkt (20) angeordnet sind.7. Vacuum pump according to one of claims 1-6, characterized in that the axial bearing (40) is arranged approximately radially of the center of gravity (20) of the rotor (12) and between two radial bearings (16, 18), each axially spaced from the Rotor center of gravity (20) are arranged.
8. Vakuumpumpe nach einem der Ansprüche 1-7, dadurch gekennzeichnet, dass die Magnetspule (42,-241-243) radial außen oder innen der Permanentmagnete (54; 254) angeordnet ist8. Vacuum pump according to one of claims 1-7, characterized in that the magnetic coil (42, -241-243) is arranged radially outside or inside of the permanent magnets (54; 254)
9. Vakuumpumpe nach einem der Ansprüche 1-8, dadurch gekennzeichnet, dass der Luftspalt zwischen dem Jocheisen (340) und dem Kompensationsmagneten (354) zur Querebene geneigt ist . 9. Vacuum pump according to one of claims 1-8, characterized in that the air gap between the yoke (340) and the compensation magnet (354) is inclined to the transverse plane.
0. Vakuumpumpe nach einem der Ansprüche 1-9, dadurch gekennzeichnet, dass das Radial-Magnetlager (16,18) von Permanentmagnet-Ringen (22,24) gebildet wird, die axial versatzfrei zueinander angeordnet sind. 0. Vacuum pump according to one of claims 1-9, characterized in that the radial magnetic bearing (16,18) is formed by permanent magnet rings (22,24) which are arranged axially offset from one another.
EP01965186A 2000-09-02 2001-08-10 Vacuum pump Withdrawn EP1313951A1 (en)

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US20030180162A1 (en) 2003-09-25
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US6877963B2 (en) 2005-04-12
DE10043235A1 (en) 2002-03-14

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