Rapidly rotating vacuum pump

Abstract

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

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 .