Multi-stage vacuum pump

Abstract

A multi-stage vacuum pump includes a plurality of rotor elements ( 14, 16 ) disposed on a common shaft ( 10 ) in a pump housing ( 12 ) for configuring multiple pump stages ( 18, 24, 26 ). The shaft is driven by an electric motor ( 40 ). An inner bearing element ( 42 ) is disposed between two rotor elements ( 14, 16 ) such that a mechanically favorable bearing arrangement is implemented using a simple configuration of the bearing elements ( 42, 44 ) as roller bearings. This is possible in particular due to the separation into two rotor elements ( 14, 16 ).

1 . A multi-stage vacuum pump, comprising:
 a plurality of rotor elements arranged on a common shaft in a pump housing to form a plurality of pump stages,   a drive element for driving said shaft, and   an inner bearing element arranged between two rotor elements.   
     
     
         2 . The multi-stage vacuum pump according to  claim 1 , wherein said inner bearing element is fixed via a holding element comprising at least one throughflow opening. 
     
     
         3 . The multi-stage vacuum pump according to  claim 2 , wherein said inner bearing element is connected to the pump housing via said holding element. 
     
     
         4 . The multi-stage vacuum pump according to  claim 2 , wherein said holding element is substantially round. 
     
     
         5 . The multi-stage vacuum pump according to  claim 2 , wherein said holding element is arranged between two rotor elements. 
     
     
         6 . The multi-stage vacuum pump according  claim 1 , wherein, along the axial direction, said inner bearing element is arranged at least partially within a rotor element. 
     
     
         7 . The multi-stage vacuum pump according to  claim 1 , wherein a rotor element is arranged between said inner bearing element and an outer bearing element. 
     
     
         8 . The multi-stage vacuum pump according to  claim 7 , wherein said outer bearing element is arranged between two rotor elements. 
     
     
         9 . The multi-stage vacuum pump according to  claim 7 , wherein said inner bearing element and/or said outer bearing element are configured as rolling bearings. 
     
     
         10 . The multi-stage vacuum pump according to  claim 9 , wherein said rolling bearing is grease-lubricated. 
     
     
         11 . The multi-stage vacuum pump according to  claim 2 , wherein the holding element defines a plurality of throughflow openings which are shaped as partial ring segments. 
     
     
         12 . The multi-stage vacuum pump according to  claim 7 , wherein the rotor element is tightly connected to the shaft. 
     
     
         13 . The multi-stage vacuum pump according to  claim 8 , wherein the outer bearing element is fixed via a holding element comprising throughflow openings. 
     
     
         14 . The multi-stage vacuum pump according to  claim 9 , wherein the inner bearing element and/or the outer bearing element are roller bearings. 
     
     
         15 . A multi-stage vacuum pump comprising:
 a pump housing which defines at least a first inlet and a second inlet and an outlet;   a drive shaft;   a first rotor element mounted to the drive shaft and configured to draw gas into the housing through the first inlet;   a second rotor mounted to the drive shaft and configured to draw gas into the housing through the second inlet and to push the gas drawn into the housing through the first and second inlets out the outlet;   a first bearing mounted to the shaft on an opposite side of the first rotor element from the first inlet to rotatably support the shaft in the housing;   a second bearing mounted to the shaft on a side of the second rotor element facing the outlet to rotatably support the shaft in the housing; and   a motor mounted around the shaft between the first and second bearings to rotate the shaft and the first and second rotor elements.