High rotational speed vacuum pump

Abstract

A high rotational speed vacuum pump ( 10 ) includes a compressor ( 12 ), a drive motor ( 14 ) for driving said compressor ( 12 ), and a motor control unit ( 16 ) for operating said drive motor ( 14 ) at a constant nominal rotational frequency. Depending on the basic conditions, undesirably strong oscillations may occur at the compressor ( 12 ) during compressor operation at the nominal rotational frequency. These undesirably strong oscillations cause the bearings to be excessively stressed. To reduce the oscillation stress of the compressor and/or the vacuum pump, an activatable rotational frequency correction device ( 18 ) is associated with the motor control unit ( 16 ). The correction device constantly corrects the nominal frequency by a rotational frequency correction value of max. 10% of the nominal rotational frequency when the rotational frequency correction device ( 18 ) is activated. This allows the rotational frequency of the drive motor ( 14 ) to be changed in a simple manner when strong natural oscillations of the compressor ( 12 ) and/or the vacuum pump ( 10 ) occur such that resonance effects and the like can be avoided.

1 . A high rotational speed vacuum pump comprising
 a compressor,   a drive motor for driving said compressor,   a motor control unit for operating said drive motor at a constant nominal rotational frequency, and   an activatable rotational frequency correction device associated with said motor control unit, said correction device constantly correcting the nominal rotational frequency by a rotational frequency correction value of max. 10% of the nominal rotational frequency when said nominal rotational frequency correction device is activated.   
   
   
       2 . The high rotational speed vacuum pump according to  claim 1 , further including: a rotational frequency correction activator which is connectable to the rotational frequency correction device for activating the latter. 
   
   
       3 . The high rotational speed vacuum pump according to  claim 2 , wherein the rotational frequency correction activator includes an external electronic storage element which is electrically connectable to the rotational frequency correction device. 
   
   
       4 . The high rotational speed vacuum pump according to  claim 3 , wherein the rotational frequency correction activator includes a dongle which is connectable to an electric interface of the rotational frequency correction device. 
   
   
       5 . The high rotational speed vacuum pump according to  claim 1 , further including: an oscillation sensor connected with the rotational frequency correction device and associated with the compressor, wherein said rotational frequency correction device is activated when said oscillation sensor detects that a predetermined oscillation amplitude has been exceeded. 
   
   
       6 . The high rotational speed vacuum pump according to  claim 5 , wherein the rotational frequency correction device stores at least two different rotational frequency correction values. 
   
   
       7 . The high rotational speed vacuum pump according to  claim 5 , further including: a control device associated with the rotational frequency correction device, said control device controlling the motor rotational frequency and receiving the controlled variable from the vibration sensor. 
   
   
       8 . A method for operating a high rotational speed vacuum pump having a compressor, a drive motor for driving said compressor, and a motor control unit for operating the drive motor at a constant nominal rotational frequency, the method comprising the following method steps:
 determining natural oscillations of the compressor by means of an oscillation sensor,   when the natural oscillations of the compressor exceed a predetermined limit value, changing the rotational frequency of the drive motor by a value less than 10% of the nominal rotational frequency of the drive motor and,   operating the drive motor at the changed rotational frequency.   
   
   
       9 . A method for operating the high speed rotational vacuum pump of  claim 1  comprising:
 determining natural oscillations of the compressor by means of an oscillation sensor,   when the natural oscillations of the compressor exceed a predetermined limit value, changing the rotational frequency of the drive motor by a value less than 10% of the nominal rotational frequency of the drive motor and,   operating the drive motor at the changed rotational frequency.   
   
   
       10 . A high speed rotational vacuum pump comprising:
 a turbomolecular device;   a drive motor which drives the turbomolecular device;   a motor control unit which controls the drive motor to operate at a constant rotational frequency;   a rotational frequency correction device which causes the motor control lunit to decrement or increment the constant rotational frequency to inhibit the constant rotational frequency from corresponding to a resonant frequency of the turbomolecular device.   
   
   
       11 . The high speed rotational vacuum pump according to  claim 10 , further including:
 an oscillation sensor which senses oscillations indicative of operation approaching a resonant frequency, the rotational frequency correction device causing the motor control unit to decrement or increment the constant rotational frequency in response to sensed oscillations indicative of operation approaching a resonant frequency.   
   
   
       12 . The high speed rotational vacuum pump according to  claim 10 , further including:
 an electronic storage element which selectively instructs the rotational frequency correction device to cause the motor control unit to increment or decrement the constant rotational frequency.