Screw vacuum pump comprising additional flow bodies

Abstract

The invention relates to a screw vacuum pump comprising two rotors ( 4, 5 ) which respectively have a hub ( 6, 7 ) and a thread ( 8, 9 ), additionally comprising a housing ( 2 ) wherein the rotors whose threads engage with each other are accommodated in such a way that they form, together with the housing, inlet cross sections ( 15, 16 ) on the inlet side thereof and form outlet cross sections ( 29 ) on the pressure side thereof causing gas to be conveyed from the inlet side to the pressure side during rotation of the rotors ( 4, 5 ). According to the invention, in order to improve inflow and outflow conditions, the rotors ( 4, 5 ) are provided on the inlet side with flow bodies ( 21, 22; 26, 27, 28; 36, 37 ) which are arranged upstream from the inlet cross sections ( 15, 16 ) in such a way that the inflow conditions of the gas to be transported to the inlet cross sections ( 15, 16 ) are improved.

1 . Screw vacuum pump comprising two rotors ( 4 ,  5 ) which respectively have a hub ( 6 ,  7 ) and a thread ( 8 ,  9 ), additionally comprising a housing ( 2 ) wherein the rotors whose threads engage with each other are accommodated in such a way that they form, together with the housing, inlet cross sections ( 15 ,  16 ) on the inlet side thereof and form outlet cross sections ( 29 ) on the pressure side thereof causing gas to be conveyed from the inlet side to the pressure side during rotation of the rotors ( 4 ,  5 ), wherein the rotors ( 4 ,  5 ) are provided on the inlet side with flow bodies ( 21 ,  22 ;  26 ,  27 ,  28 ;  36 ,  37 ) which are arranged upstream from the inlet cross sections ( 15 ,  16 ) in such a manner that the conditions for the inflow of the gases to be conveyed to the inlet cross sections ( 15 ,  16 ) are improved.  
     
     
         2 . Pump according to  claim 1 , wherein in the instance of multi-thread screws, at least one thread ridge is equipped with a flow body.  
     
     
         3 . Pump according to  claim 1 , wherein the flow body extends in the instance of a single thread screw over 90° to 180°.  
     
     
         4 . Pump according to one of the claims  1 ,  2  or  3 , wherein the flow body ( 21 ,  22 ) substantially is an extension of the ridge ( 8 ,  9 ) with reduced ridge width.  
     
     
         5 . Pump according to one of the  claims 1  to  4 , wherein there is located in the area of the respective inlet cross-sections at least one further flow body independent of thread ridge ( 8 ,  9 ), said flow body having the shape of the blade.  
     
     
         6 . Pump according to  claim 5 , wherein the blades are curved such that they extend on the pressure side approximately in the direction of the thread ridges ( 8 ,  9 ) and are designed to be steeper on the intake side.  
     
     
         7 . Pump according to one of the above claims, wherein in the area running behind the face side of the thread ridge ( 8 ,  9 ) there is present a recess ( 23 ,  24 ).  
     
     
         8 . Pump according to one of the above claims, wherein the rotor outlet is equipped with corresponding flow bodies.  
     
     
         9 . Pump according to one of the above claims, wherein the flow body/bodies ( 21 ,  22 ;  26 ,  27 ,  28 ;  31 ,  32 ,  33 ;  34 ,  35 ;  36 ,  37 ) and the corresponding hub section ( 6 ,  7 ) are fitted by way of a separate component to the face side respectively the rear side of the rotor ( 4 ,  5 ).  
     
     
         10 . Pump according to one of the above claims, wherein the flow bodies with respect to their design, arrangement and/or mass are so designed that they substantially remove the imbalance of the related rotor ( 4 ,  5 )  
     
     
         11 . Screw vacuum pump comprising two rotors ( 4 ,  5 ) which respectively have a hub ( 6 ,  7 ) and a thread ( 8 ,  9 ), additionally comprising a housing ( 2 ) wherein the rotors whose threads engage with each other are accommodated in such a way that they form, together with the housing, inlet cross sections ( 15 ,  16 ) on the inlet side thereof and form outlet cross sections ( 29 ) on the pressure side thereof causing gas to be conveyed from the inlet side to the pressure side during rotation of the rotors ( 4 ,  5 ), wherein the rotors ( 4 ,  5 ) are provided on the pressure side and/or inlet side with balancing weights ( 21 ,  22 ;  26 ,  27 ,  28 ;  31 ,  32 ,  33 ;  34 ,  35 ;  36 ,  37 ) which are designed in such a manner that they improve the conditions for the inflow (respectively outflow) of the gases to be conveyed.  
     
     
         12 . Pump according to  claim 11  wherein the balancing weights exhibit the shape of flow bodies in accordance with one of the  claims 1  to  10 .