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

• High-speed vacuum pumps which are in particular magnetic bearing non-displaceable turbomolecular pumps, need safe overspeed protection, as overspeeds due to centrifugal forces not only lead to the destruction of the vacuum pump, but also pose a high risk to persons.
• the object of the invention is to provide a high-speed vacuum pump with a simple and reliable overspeed protection.
• the rotor is designed so that its bending-critical mating resonance frequency lies between 3% and at most 30% above the constant nominal rotational frequency.
• the adjustment of the bending-critical resonance frequency in the counterflow such that it is between 3% and at most 30% above the constant nominal rotational frequency can be carried out in many ways.
• the mass, the geometry and the bearing of the rotor of the vacuum pump can be changed and adjusted so that the bending critical resonance frequency in the opposite direction is at most 30% above the nominal rotational frequency and in this way an overspeed is prevented.
• the resonant vibrations at the bending-critical resonant frequency in the opposite direction consume a great deal of power, so that driving through to an overlying rotational frequency would only be possible with a considerable power surplus.
• the drive power of the electric drive motor must be designed so that they of the resonant vibrations at a rotational frequency in the range of bending critical Resonant frequency is completely consumed in the opposite direction. In this way an immanent hardware overspeed protection is provided whose failure is virtually eliminated. The cost of an active overspeed protection is eliminated, so that the cost of overspeed protection are significantly reduced.
• the critical bending frequencies are at relatively high frequencies. Therefore, the bending critical resonance frequency in the opposite direction is particularly suitable to be used as immanent overspeed protection.
• the rotor of the vacuum pump is supported by a magnetic bearing.
• a magnetic bearing By this is meant in the present case a magnetic bearing with respect to at least one radial degree of freedom.
• the rotor of a high-speed vacuum pump is magnetically supported with respect to all five degrees of freedom when a magnetic bearing is provided.
• the magnetic bearing generated during operation in turn by the balancing radial vibrations of the rotor.
• a suitable magnetic bearing control algorithm is used to pass through the critical bending resonance frequencies.
• Such a suitable control algorithm is not provided in the present case. Rather, the magnetic bearing control algorithm is designed so that the critical bending resonance frequencies can not be traversed with the available drive power.
• the bending-critical resonance frequency is in the opposite direction between 5% and 25% of the nominal rotational frequency, in particular in the range of about 20% above the nominal rotational frequency.
• a distance of about 20% above the nominal rotational frequency provides sufficient safety with respect to the overshoot of the rotational frequency during startup of the rotor from a standstill to the nominal rotation frequency. In this way, the accidental achievement of the critical bending resonance frequency in the opposite direction can be avoided by overshoot at startup.
• the bending-critical resonance frequency in the opposite direction should be as close as possible above the nominal rotational frequency in order not to have to interpret the rotor unnecessarily stable.
• the high-speed vacuum pump is a non-displacing vacuum pump, for example a turbomolecular vacuum pump.
• a turbomolecular vacuum pump speeds of 10,000 to 100,000 rpm are common.
• Such high speeds or rotational frequencies suggest for the storage of the rotor in particular a magnetic bearing.
• the figure shows a so-called Campbell diagram for a high-speed vacuum pump.
• the resonant frequency f res of the rotor is shown above the rotational frequency f rot of the rotor.
• the high-speed vacuum pump is a turbomolecular vacuum pump whose rotor is mounted in a five-axis configuration by means of a magnetic bearing.
• the rotor is driven by an electric drive motor and operated at a constant fixed nominal rotational frequency f nom .
• the bending-critical resonance frequency f crit is in the opposite direction for the rotor of the vacuum pump at approximately 970 Hz.
• the nominal rotation frequency f ⁇ om the vacuum pump or the drive motor, the drive motor control, and the rotor is approximately 800 Hz. This is the critical bending resonant frequency f crit in the counter run about 21% above the nominal rotational frequency f nom of the vacuum pump.
• the drive power of the electric motor is limited so that it is completely consumed by the reverse resonance vibrations when the rotor rotational frequency fro t should reach the critical bending resonance frequency f cri t in the opposite direction once.
• the vacuum pump has no further active overspeed protection, i. has no second speed control circuit, which is provided in addition to the speed control circuit of the engine control.
• the bending-critical mating resonance frequency curve 16 can not be influenced by appropriate adjustment of the control parameters of the magnetic bearing of the vacuum pump.
• the control parameters of the magnetic bearing are designed so that the bending-critical resonance frequencies are excited so strong that with the available drive energy driving through the bending-critical resonance frequencies is excluded.
• the magnetic bearing control parameters are to be interpreted relatively soft.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Thermal Sciences (AREA)
• Non-Positive Displacement Air Blowers (AREA)
• Magnetic Bearings And Hydrostatic Bearings (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
• Compressor (AREA)
• Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
• Applications Or Details Of Rotary Compressors (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39322764

Family Applications (1)

Country Status (8)

Cited By (2)

Families Citing this family (1)

Citations (5)

Family Cites Families (11)

• 2007
  • 2007-02-24 DE DE102007009080A patent/DE102007009080A1/de not_active Withdrawn
• 2008
  • 2008-02-15 KR KR1020097019677A patent/KR20090113341A/ko not_active Application Discontinuation
  • 2008-02-15 JP JP2009550267A patent/JP5498171B2/ja active Active
  • 2008-02-15 AT AT08716880T patent/ATE488700T1/de active
  • 2008-02-15 US US12/528,192 patent/US20100322798A1/en not_active Abandoned
  • 2008-02-15 CN CN2008800058397A patent/CN101617125B/zh active Active
  • 2008-02-15 DE DE502008001821T patent/DE502008001821D1/de active Active
  • 2008-02-15 WO PCT/EP2008/051874 patent/WO2008101876A1/de active Application Filing
  • 2008-02-15 EP EP08716880A patent/EP2118492B1/de active Active

Patent Citations (6)

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