US20100322798A1 - Rapidly rotating vacuum pump - Google Patents

Rapidly rotating vacuum pump Download PDF

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Publication number
US20100322798A1
US20100322798A1 US12/528,192 US52819208A US2010322798A1 US 20100322798 A1 US20100322798 A1 US 20100322798A1 US 52819208 A US52819208 A US 52819208A US 2010322798 A1 US2010322798 A1 US 2010322798A1
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US
United States
Prior art keywords
vacuum pump
rotor
rotational
frequency
bending
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.)
Abandoned
Application number
US12/528,192
Inventor
Heinrich Englaender
Christian Harig
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
Oerlikon Leybold Vacuum 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 Oerlikon Leybold Vacuum GmbH filed Critical Oerlikon Leybold Vacuum GmbH
Assigned to OERLIKON LEYBOLD VACUUM GMBH reassignment OERLIKON LEYBOLD VACUUM GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ENGLAENDER, HEINRICH, HARIG, CHRISTIAN
Publication of US20100322798A1 publication Critical patent/US20100322798A1/en
Abandoned legal-status Critical Current

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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
    • 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
    • F04D19/042—Turbomolecular vacuum pumps
    • 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
    • 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
    • F04D29/00—Details, component parts, or accessories
    • F04D29/06—Lubrication
    • 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
    • F04D29/58—Cooling; Heating; Diminishing heat transfer
    • 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
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/668—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps damping or preventing mechanical vibrations

Definitions

  • Rapidly rotating vacuum pumps i.e. particularly magnetically supported turbomolecular pumps of the non-displacement type, require a reliable overspeed protection since, due to centrifugal forces, rotational speeds in the overspeed range do not only lead to destruction of the vacuum pump but may also cause considerable danger to persons.
  • the rotor is designed to the effect that its bending-critical counter-rotational resonance frequency is between 3% and a maximum of 30% above the nominal rotational frequency.
  • no active overspeed protection i.e. no direct controlling and limiting of the rotational speed which would exist in addition to the control means for the electric drive motor.
  • the process of setting the bending-critical counter-rotational resonance frequency to a frequency between 3% and a maximum of 30% above the nominal rotational frequency can be performed in various manners.
  • the mass, the geometry and the support of the rotor of the vacuum pump can be changed and adapted in such a manner that the bending-critical counter-rotational resonance frequency will be maximally 30% above the nominal rotational frequency, thus immanently preventing an overspeed.
  • the resonance vibrations at the bending-critical counter-rotational resonance frequency will consume considerable power so that a run-up to a rotational frequency at a level thereabove would be possible only with a massive power reserve.
  • the drive power of the electric drive motor has to be set in a manner allowing it to be completely consumed by the resonance vibrations at a rotational frequency in the range of the bending-critical counter-rotational resonance frequency.
  • the bending-critical frequencies are situated on relatively high frequency levels. For this reason, the bending-critical counter-rotational resonance frequency is especially suited to be utilized for immanent overspeed protection.
  • the rotor of the vacuum pump is supported by a magnetic bearing.
  • a magnetic bearing is to be understood herein as a magnetic bearing with respect to at least one radial degree of freedom.
  • the rotor of a rapidly rotating vacuum pump is magnetically supported with respect to all five degrees of freedom if a magnetic bearing is provided.
  • the magnetic bearing itself will generate radial vibrations of the rotor due to the counterbalancing control. Thereby, particularly also bending-critical vibrations are activated, and it will not be possible for the pump to pass through these vibrations as long as no suitable magnetic-support control algorithm is provided for passing through the bending-critical resonance frequencies.
  • Such a suitable control algorithm is not provided herein.
  • the magnetic-support control algorithm is configured to the effect that, on the basis of the available drive energy, the pump cannot pass through the bending-critical resonance frequencies.
  • the bending-critical counter-rotational resonance frequency is between 5% and 25% of the nominal rotational frequency, and more preferably it is in the range of 20% above the nominal rotational frequency.
  • An interval of about 20% above the nominal rotational frequency will offer sufficient safety from overshoot beyond the rotational frequency in the process of running up the rotor from standstill to the nominal rotational frequency. During run-up, it can thus be avoided that said overshoot will undesirably cause the occurrence of bending-critical counter-rotational resonance frequencies.
  • the bending-critical counter-rotational resonance frequency should be as closely as possible above the nominal rotational frequency, thus obviating the requirement of a rotor design having an unnecessary extent of stability.
  • the rapidly rotating vacuum pump is a vacuum pump of the non-displacement type, e.g. a turbomolecular vacuum pump.
  • the rotational speeds are usually in the range from 10,000 to 100,000 r/min. Rotational speeds and respectively rotational frequencies in such a high range make it especially advisable to use a magnetic bearing for supporting the rotor.
  • the FIGURE shows a so-called Campbell diagram for a rapidly rotating vacuum pump.
  • the resonance frequency f res of the rotor is plotted over the rotational frequency f rot of the rotor.
  • the rapidly rotating vacuum pump herein is a turbomolecular vacuum pump whose rotor is supported completely in a five-axial arrangement by means of a magnetic bearing.
  • the rotor is driven by an electric drive motor and is operated at a constant predetermined nominal rotational frequency f nom .
  • the bending-critical counter-rotational resonance frequency f crit for the rotor of the vacuum pump is substantially 970 Hz.
  • the nominal rotational frequency f nom of the vacuum pump and respectively of the drive motor, the drive motor control unit and the rotor is substantially 800 Hz.
  • the bending-critical counter-rotational resonance frequency f crit is substantially 21% above the nominal rotational frequency f nom of the vacuum pump.
  • the drive power of the electric motor is limited in such a manner that it will be completely consumed by the counter-rotational resonance frequencies in case that the rotational frequency of the rotor should happen to reach the bending-critical counter-rotational resonance frequency f crit .
  • the vacuum pump does not comprise any further active overspeed protection, i.e. it does not comprise a second rotational-speed control loop provided in addition to the rotational-speed control loop of the motor control.
  • the curve 16 representing the bending-critical counter-rotational resonance frequency cannot be influenced by a corresponding setting of the control parameters of the magnetic bearing of the vacuum pump.
  • the control parameters of the magnetic bearing are provided to the effect that the bending-critical resonance frequencies will be activated strongly enough to exclude that an operation with the drive energy available would allow the pump to pass through the bending-critical resonance frequencies.
  • the control parameters for the magnetic bearings should be relatively soft.

Abstract

A rapidly rotating vacuum pump includes: a magnet-mounted rotor driven by an electric drive motor with a predetermined constant nominal rotational frequency (fnom). The rotor and a rotor bearing are embodied in such a way that the bending-critical counter-rotational resonance frequency (fcrit) is between 3% and a maximum of 30% above the nominal rotational frequency (fnom), thereby preventing an overspeed.

Description

  • Rapidly rotating vacuum pumps, i.e. particularly magnetically supported turbomolecular pumps of the non-displacement type, require a reliable overspeed protection since, due to centrifugal forces, rotational speeds in the overspeed range do not only lead to destruction of the vacuum pump but may also cause considerable danger to persons.
  • In practice, overspeed protection of rapidly rotating vacuum pumps is effected by use of complex electronic assemblies which are operative to monitor the rotational speed of the rotor and respectively of the electric drive motor, and to delimit the rotational speed by electronic means. Although it is in this manner possible, by high technical expenditure and redundant hard- and software, to realize a safe active overspeed protection for rapidly rotating vacuum pumps, the resultant high technical expenditure will cause considerable costs.
  • It is an object of the invention to provide a rapidly rotating vacuum pump which is equipped with a simple and reliable overspeed protection.
  • According to the invention, the above object is achieved by the features of claim 1.
  • In the rapidly rotating vacuum pump of the invention, the rotor is designed to the effect that its bending-critical counter-rotational resonance frequency is between 3% and a maximum of 30% above the nominal rotational frequency. There is provided no active overspeed protection, i.e. no direct controlling and limiting of the rotational speed which would exist in addition to the control means for the electric drive motor.
  • The process of setting the bending-critical counter-rotational resonance frequency to a frequency between 3% and a maximum of 30% above the nominal rotational frequency can be performed in various manners. Particularly the mass, the geometry and the support of the rotor of the vacuum pump can be changed and adapted in such a manner that the bending-critical counter-rotational resonance frequency will be maximally 30% above the nominal rotational frequency, thus immanently preventing an overspeed. The resonance vibrations at the bending-critical counter-rotational resonance frequency will consume considerable power so that a run-up to a rotational frequency at a level thereabove would be possible only with a massive power reserve. The drive power of the electric drive motor has to be set in a manner allowing it to be completely consumed by the resonance vibrations at a rotational frequency in the range of the bending-critical counter-rotational resonance frequency. Thus, there is created an immanent overspeed protection by means of hardware, wherein failure is virtually excluded. The expenditure for an active overspeed protection can be omitted, allowing for a considerable reduction of the costs for overspeed protection.
  • In contrast to rigid-body-critical resonance frequencies, which are relatively low and normally can be passed through quickly and with relatively little power reserve, the bending-critical frequencies are situated on relatively high frequency levels. For this reason, the bending-critical counter-rotational resonance frequency is especially suited to be utilized for immanent overspeed protection.
  • The rotor of the vacuum pump is supported by a magnetic bearing. A magnetic bearing is to be understood herein as a magnetic bearing with respect to at least one radial degree of freedom. In practice, however, the rotor of a rapidly rotating vacuum pump is magnetically supported with respect to all five degrees of freedom if a magnetic bearing is provided. During operation, the magnetic bearing itself will generate radial vibrations of the rotor due to the counterbalancing control. Thereby, particularly also bending-critical vibrations are activated, and it will not be possible for the pump to pass through these vibrations as long as no suitable magnetic-support control algorithm is provided for passing through the bending-critical resonance frequencies. Such a suitable control algorithm is not provided herein. Instead, the magnetic-support control algorithm is configured to the effect that, on the basis of the available drive energy, the pump cannot pass through the bending-critical resonance frequencies.
  • Preferably, the bending-critical counter-rotational resonance frequency is between 5% and 25% of the nominal rotational frequency, and more preferably it is in the range of 20% above the nominal rotational frequency. An interval of about 20% above the nominal rotational frequency will offer sufficient safety from overshoot beyond the rotational frequency in the process of running up the rotor from standstill to the nominal rotational frequency. During run-up, it can thus be avoided that said overshoot will undesirably cause the occurrence of bending-critical counter-rotational resonance frequencies. On the other hand, the bending-critical counter-rotational resonance frequency should be as closely as possible above the nominal rotational frequency, thus obviating the requirement of a rotor design having an unnecessary extent of stability.
  • Preferably, the rapidly rotating vacuum pump is a vacuum pump of the non-displacement type, e.g. a turbomolecular vacuum pump. In turbomolecular vacuum pumps, the rotational speeds are usually in the range from 10,000 to 100,000 r/min. Rotational speeds and respectively rotational frequencies in such a high range make it especially advisable to use a magnetic bearing for supporting the rotor.
  • The invention will be explained in greater detail hereunder with reference to the FIGURE.
  • The FIGURE shows a so-called Campbell diagram for a rapidly rotating vacuum pump.
    •
  • In the Campbell diagram presented in the FIGURE, the resonance frequency fres of the rotor is plotted over the rotational frequency frot of the rotor.
  • The rapidly rotating vacuum pump herein is a turbomolecular vacuum pump whose rotor is supported completely in a five-axial arrangement by means of a magnetic bearing. The rotor is driven by an electric drive motor and is operated at a constant predetermined nominal rotational frequency fnom.
  • Represented in the diagram are, first, in a lower range of rotational speeds, respectively two by two rigid-body-critical resonance frequency curves 12,14. These resonance frequencies will change to a relatively slight extent along with the rotational frequency fret of the rotor. Further shown are, in a higher range of rotational speeds, a curve 16 representing the bending-critical counter-rotational resonance frequency and a curve 18 representing the bending-critical co-rotational resonance frequency. Further, represented in an interrupted line, the so-called position vector 20 is shown. At the point where the position vector 20 intersects the bending-critical counter-rotational resonance frequency curve 20, the bending-critical counter-rotational resonance frequency fcrit for the present vacuum pump can be read out.
  • In the present example, the bending-critical counter-rotational resonance frequency fcrit for the rotor of the vacuum pump is substantially 970 Hz. The nominal rotational frequency fnom of the vacuum pump and respectively of the drive motor, the drive motor control unit and the rotor is substantially 800 Hz. Thus, the bending-critical counter-rotational resonance frequency fcrit is substantially 21% above the nominal rotational frequency fnom of the vacuum pump.
  • The drive power of the electric motor is limited in such a manner that it will be completely consumed by the counter-rotational resonance frequencies in case that the rotational frequency of the rotor should happen to reach the bending-critical counter-rotational resonance frequency fcrit.
  • The vacuum pump does not comprise any further active overspeed protection, i.e. it does not comprise a second rotational-speed control loop provided in addition to the rotational-speed control loop of the motor control.
  • The curve 16 representing the bending-critical counter-rotational resonance frequency cannot be influenced by a corresponding setting of the control parameters of the magnetic bearing of the vacuum pump. However, the control parameters of the magnetic bearing are provided to the effect that the bending-critical resonance frequencies will be activated strongly enough to exclude that an operation with the drive energy available would allow the pump to pass through the bending-critical resonance frequencies. For thus purpose, the control parameters for the magnetic bearings should be relatively soft.

Claims (10)

1. A rapidly rotating vacuum pump, comprising a rotor driven by an electric drive motor and having a predetermined constant nominal rotational frequency, wherein
said rotor is supported by a magnetic bearing,
a bending-critical counter-rotational resonance frequency of the rotor is between 3% and a maximum of 30% above the predetermined nominal rotational frequency, and
no active overspeed protection is provided.
2. The rapidly rotating vacuum pump according to claim 1, wherein said vacuum pump is a non-displacing vacuum pump.
3. The rapidly rotating vacuum pump according to claim 2, wherein said vacuum pump is a turbomolecular pump.
4. The rapidly rotating vacuum pump according to claim 3, wherein the bending-critical counter-rotational resonance frequency is between 5% and 25% of the predetermined nominal rotational frequency.
5. A vacuum pump having a rotor, a stator, magnetic bearings, and a drive motor which accelerates the rotor to and rotates the rotor at a preselected nominal rotational frequency of at least 10,000 rpm, thr rotor comprising:
a mass and geometry which defines a binding-critical counter-rotational resonance frequency which is at least 3% greater than the predetermined nominal rotation frequency, such that the rotor is constrained to rotate at speeds below its bending-critical counter-rotational resonance frequency.
6. The vacuum pump according to claim 5, wherein the binding-critical counter-rotational resonance frequency is less than 30% greater than the preselected nominal rotational frequency.
7. The vacuum pump according to claim 5, wherein the drive motor and the magnetic bearings are free of electronic active overspeed protection.
8. A method of designing a vacuum pump including designing a rotor and a rotor bearing such that a bending-critical counter-rotational resonance frequency is between 3% and 30% greater than a nominal rotational frequency.
9. A rotor made by the method according to claim 8.
10. A vacuum pump made by the method of claim 8.
US12/528,192 2007-02-24 2008-02-15 Rapidly rotating vacuum pump Abandoned US20100322798A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102007009080A DE102007009080A1 (en) 2007-02-24 2007-02-24 Fast-rotating vacuum pump
DE102007009080.5 2007-02-24
PCT/EP2008/051874 WO2008101876A1 (en) 2007-02-24 2008-02-15 Rapidly rotating vacuum pump

Publications (1)

Publication Number Publication Date
US20100322798A1 true US20100322798A1 (en) 2010-12-23

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US12/528,192 Abandoned US20100322798A1 (en) 2007-02-24 2008-02-15 Rapidly rotating vacuum pump

Country Status (8)

Country Link
US (1) US20100322798A1 (en)
EP (1) EP2118492B1 (en)
JP (1) JP5498171B2 (en)
KR (1) KR20090113341A (en)
CN (1) CN101617125B (en)
AT (1) ATE488700T1 (en)
DE (2) DE102007009080A1 (en)
WO (1) WO2008101876A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2970053B1 (en) 2011-01-05 2013-01-25 Turbomeca DEVICE AND METHOD FOR MECHANICAL PROTECTION
FR2974400B1 (en) 2011-04-22 2013-05-10 Turbomeca MECHANICAL PROTECTION DEVICE
DE102020134924A1 (en) 2020-12-23 2022-06-23 Huga Kg Door leaf with flush handle fitting

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US4946345A (en) * 1988-03-18 1990-08-07 Ebara Research Co., Ltd. Turbo-molecular pump
US5541857A (en) * 1992-08-10 1996-07-30 Dow Deutschland Inc. Process and device for monitoring vibrational excitation of an axial compressor
US5833374A (en) * 1997-05-19 1998-11-10 Varian Associates, Inc. Rotatable assembly for supporting of the rotor of a vacuum pump
US20010012488A1 (en) * 1999-12-21 2001-08-09 Yoshinobu Ohtachi Vaccum pump
US6664683B1 (en) * 1999-01-29 2003-12-16 Ibiden Co., Ltd Motor and turbo-molecular pump
US6891280B2 (en) * 2000-04-05 2005-05-10 Aerodyn Engineering Gmbh Method for operating offshore wind turbine plants based on the frequency of their towers
US20090202360A1 (en) * 2004-10-07 2009-08-13 Voelker Karl-Heinrich High rotational speed vacuum pump

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JP2000073986A (en) * 1998-08-28 2000-03-07 Jeol Ltd Vibration restraining unit for turbo-molecular pump
JP2002174238A (en) * 2000-12-07 2002-06-21 Seiko Instruments Inc Magnetic bearing control device and vacuum pump using the same
JP2004116354A (en) * 2002-09-25 2004-04-15 Mitsubishi Heavy Ind Ltd Turbo molecular pump
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Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4946345A (en) * 1988-03-18 1990-08-07 Ebara Research Co., Ltd. Turbo-molecular pump
US5541857A (en) * 1992-08-10 1996-07-30 Dow Deutschland Inc. Process and device for monitoring vibrational excitation of an axial compressor
US5833374A (en) * 1997-05-19 1998-11-10 Varian Associates, Inc. Rotatable assembly for supporting of the rotor of a vacuum pump
US6664683B1 (en) * 1999-01-29 2003-12-16 Ibiden Co., Ltd Motor and turbo-molecular pump
US20010012488A1 (en) * 1999-12-21 2001-08-09 Yoshinobu Ohtachi Vaccum pump
US6575713B2 (en) * 1999-12-21 2003-06-10 Seiko Instruments Inc. Vaccum pump
US6891280B2 (en) * 2000-04-05 2005-05-10 Aerodyn Engineering Gmbh Method for operating offshore wind turbine plants based on the frequency of their towers
US20090202360A1 (en) * 2004-10-07 2009-08-13 Voelker Karl-Heinrich High rotational speed vacuum pump

Non-Patent Citations (1)

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Title
Development of Long-Life Auxiliary Bearings for Critical Service Turbomachinery and High-speed Motors by Reitsma, August 2002. *

Also Published As

Publication number Publication date
DE502008001821D1 (en) 2010-12-30
KR20090113341A (en) 2009-10-29
WO2008101876A1 (en) 2008-08-28
CN101617125A (en) 2009-12-30
EP2118492A1 (en) 2009-11-18
EP2118492B1 (en) 2010-11-17
JP5498171B2 (en) 2014-05-21
JP2010519453A (en) 2010-06-03
CN101617125B (en) 2011-06-08
DE102007009080A1 (en) 2008-08-28
ATE488700T1 (en) 2010-12-15

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AS Assignment

Owner name: OERLIKON LEYBOLD VACUUM GMBH, GERMANY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ENGLAENDER, HEINRICH;HARIG, CHRISTIAN;REEL/FRAME:023130/0264

Effective date: 20090820

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION