Multi-stage friction vacuum pump

Abstract

A multi-stage vacuum pump includes at least one turbo-compressor stage ( 11 ) and is equipped with a circular compressor stage ( 33 ) on the pressure side of the turbo-compressor stage. The pump has small axial dimensions, enabling the compression to be increased without significantly increasing the space requirement.

1 . A multi-stage friction vacuum pump comprising: 
 at least one axially compressing turbo-compressor stage with a rotor rotating about its axis and having rotor discs projecting between stationary stator discs;    a radially compressing circular compressor stage arranged on the compressor side of the turbo-compressor stage, said circular compressor stage comprising a rotor having axially projecting rotor blades arranged on circular paths and a stator having axially projecting stator blades arranged on circular paths, the stator blades engaging in radial gaps between adjacent circular paths of rotor blades.    
   
   
       2 . The friction vacuum pump of  claim 1 , wherein the rotor blades of the circular compressor stage are arranged on a rotor body of the turbo-compressor stage carrying the rotor discs.  
   
   
       3 . The friction vacuum pump of  claim 1 , wherein the stator blades are arranged on a stator body of the turbo-compressor stage carrying the stator discs.  
   
   
       4 . The friction vacuum pump of  claim 1 , as a multi-inlet pump, further including: 
 at least two axially spaced, serially compressing turbo-compressor stages between which an intermediate inlet is situated, and    a circular compressor stage on the compressor side of the first turbo-compressor stage.    
   
   
       5 . The friction vacuum pump of  claim 1 , as a multi-inlet pump, further including: 
 at least two axially spaced, serially compressing turbo-compressor stages between which an intermediate inlet is situated, and    a circular compressor stage on the compressor side of the second turbo-compressor stage.    
   
   
       6 . The friction vacuum pump of  claim 1 , wherein the circular compressor stage compresses radially inward.  
   
   
       7 . The friction vacuum pump of  claim 1 , wherein in that the circular compressor stage is designed with at least two stages and alternately compresses one of radially inward and radially outward.  
   
   
       8 . The friction vacuum pump of  claim 1 , wherein the rotor blades have an axial length that tapers in a direction of compression.