Drag Vacuum Pump

Abstract

A friction vacuum pump ( 10 ) comprises a housing ( 12 ) defining a vaneless pump stator ( 30 ), a rotor drive and a rotor support which rotatably supports a pump rotor ( 16 ) provided with a vane ( 18 ). The housing ( 12 ) surrounds the overall axial length of the pump rotor ( 16 ), the rotor drive and the rotor support. Prior art housings are of multipart configuration and thus comprise seals between the housing portions. The seals are difficult to coat and may be or become locations where leaks occur. In contrast, the housing ( 12 ) is of one-piece configuration such that, in any case, the region of the housing ( 12 ) which is in contact with the vacuum gas is free of seals.

1 . A friction vacuum pump comprising:
 a housing forming a vaneless pump stator, and   a rotor drive and a rotor support which supports a pump rotor comprising a vane,   wherein said housing surrounds the overall axial length of the pump rotor, the rotor drive and the rotor support, and the housing is of one-piece configuration.   
   
   
       2 . The friction vacuum pump according to  claim 1 , characterized in that wherein the rotor support and the rotor drive are arranged in a cartridge which is supported by the housing and surrounded over its overall axial length by said housing. 
   
   
       3 . The friction vacuum pump according to  claim 2 , wherein the cartridge comprises a pot-shaped housing which is integrally formed with the friction vacuum pump housing. 
   
   
       4 . The friction vacuum pump according to  claim 2 , wherein at least 50% of the axial length of the cartridge is surrounded by the pump rotor. 
   
   
       5 . The friction vacuum pump according to  claim 2 , wherein a portion of the cartridge housing is defined by the friction vacuum pump housing. 
   
   
       6 . The friction vacuum pump according to  claim 2 , wherein the housing comprises a circular shoulder to which the cartridge is fastened. 
   
   
       7 . The friction vacuum pump according to  claim 1 , wherein the pump rotor is a screw pump rotor. 
   
   
       8 . The friction vacuum pump according to  claim 1 , the wherein a surface in a radial plane between a pump stator and a hub of the pump rotor decreases towards a discharge side. 
   
   
       9 . A friction vacuum pump comprising:
 a funnel-shaped housing which tapers from an inlet end towards a discharge end, the housing being an integral one-piece construction;   the one-piece housing including an integrally formed shoulder adjacent the discharge end, the shoulder being in a plane transverse to a central axis of the one-piece housing;   a cartridge which houses a rotor drive and a rotor support, the cartridge being supported on the integral shoulder and extending along the central axis of the one-piece housing;   a rotor having at least one vane, the rotor being supported on the rotor support and received within the housing.   
   
   
       10 . A method of assembling the friction vacuum pump of  claim 9  comprising:
 inserting the cartridge into the integral, one-piece housing from the inlet end;   attaching the cartridge to the flange;   attaching the rotor to the rotor support.