Rotary piston pump

Abstract

A rotary piston pump has at least two rotors ( 8 ) with associated drive shafts ( 26 ), wherein for each rotor ( 8 ) an associated bearing tube ( 28 ) is provided, which extends into the associated rotor ( 8 ) and through which the associated drive shaft ( 26 ) passes. Between the inside ( 24 ) of each rotor ( 8 ) and the outside of the bearing tube ( 28 ) a first gap ( 64 ) is provided. In operation, the first gap ( 64 ) contains cooling fluid and is part of a cooling fluid circuit.

1 . A rotary piston pump, comprising 
 at least two rotors with associated drive shafts,    an associated bearing tube for each rotor, said bearing tube extending into the associated rotor and through which the associated drive shaft ( 26 ) passes, and    a first gap being provided between the inside of each rotor and the outside of the bearing tube,    in operations, the first gap contains cooling fluid, is part of a cooling fluid circuit and has a cooling fluid inlet and a spatially separate cooling fluid outlet.    
   
   
       2 . The rotary piston pump as claimed in  claim 1 , wherein between the inside of the bearing tube and the outside of the drive shaft a second gap is provided, which is part of the cooling fluid circuit.  
   
   
       3 . The rotary piston pump as claimed in  claim 2 , wherein the cooling fluid circuit is formed such that cooling fluid first flows into the second gap and subsequently from the second gap into the first gap.  
   
   
       4 . The rotary piston pump as claimed in  claim 3 , wherein each bearing tube has a stationarily mounted end and a free end extending into the rotor, and, at the stationarily mounted end, the second gap has an associated cooling fluid inlet and, at the axially opposite end, the second gap has a cooling fluid outlet, which is in flow connection with a cooling fluid inlet of the first gap at the free end of the bearing tube.  
   
   
       5 . The rotary piston pump as claimed in  claim 4 , wherein between the end face of the free end of the respective bearing tube and the adjoining wall of the rotor at least one connecting passage is formed between the first and second gaps.  
   
   
       6 . The rotary piston pump as claimed in  claim 1 , wherein between the respective bearing tube and the associated drive shaft at least one bearing is provided, through which the flow of cooling fluid passes.  
   
   
       7 . The rotary piston pump as claimed in  claim 1 , wherein the respective bearing tube has a stationarily mounted end and a free end extending into the rotor, and in the vicinity of the free end a bearing is provided between the bearing tube and the associated drive shaft.  
   
   
       8 . The rotary piston pump as claimed in  claim 1 , wherein between the respective bearing tube and the associated rotor at least one bearing is arranged, through which the flow of cooling fluid passes.  
   
   
       9 . The rotary piston pump as claimed in  claim 1 , wherein the respective bearing tube has a stationarily mounted end and a free end extending into the rotor, and that in the vicinity of its own end associated with the stationarily mounted end the rotor is radially supported on the bearing tube by means of a bearing.  
   
   
       10 . The rotary piston pump as claimed in  claim 1 , wherein between the respective bearing tube and the associated drive shaft at least one bearing and an associated bypass is provided, so that cooling fluid can flow past the bearing through the bypass.  
   
   
       11 . The rotary piston pump as claimed in  claim 1 , wherein the rotors are coupled to each other via a transmission and the cooling fluid circuit is not sealed towards said transmission and towards the cooling and lubricating fluid contained therein for the transmission.  
   
   
       12 . The rotary piston pump as claimed in  claim 11 , wherein the rotors are coupled to each other via a transmission accommodated in a transmission housing and the cooling and lubricating fluid of the transmission flows into the cooling fluid circuit.  
   
   
       13 . The rotary piston pump as claimed in  claim 1 , wherein the rotors are coupled to each other via a transmission accommodated in a transmission housing and in the transmission housing a cooling fluid pump is accommodated, which is driven by the transmission and delivers the cooling fluid into the gap.  
   
   
       14 . The rotary piston pump as claimed in  claim 1 , wherein it is a vacuum screw pump or a Roots pump.  
   
   
       15 . The rotary piston pump as claimed in  claim 6 , wherein bearings for supporting the rotor on the bearing tube constitute open bearings.  
   
   
       16 . The rotary piston pump as claimed in  claim 1 , wherein the bearing tube is designed without cooling passage in its wall.  
   
   
       17 . The rotary piston pump as claimed in  claim 1 , wherein the drive shaft, at least in the vicinity of its drive-side end, constitutes a shaft without cooling passage.  
   
   
       18 . The rotary piston pump as claimed in  claim 2 , including a reservoir for cooling fluid, said cooling fluid reaching at least one of said gaps via a passage located outside the drive shaft.  
   
   
       19 . The rotary piston pump as claimed in  claim 1 , wherein the cooling fluid inlet and outlet of the first gap are provided in the vicinity of the opposite ends of the bearing tube.  
   
   
       20 . The rotary piston pump as claimed in  claim 1 , wherein it is free from seal gas.  
   
   
       21 . The rotary piston pump as claimed in  claim 1 , wherein between the respective bearing tube and the associated rotor at least one bearing and an associated bypass is provided, so that cooling fluid can flow past the bearing through the bypass.  
   
   
       22 . The rotary piston pump as claimed in  claim 6 , wherein bearings for supporting the rotor on the drive shaft in the bearing tube constitute open bearings.  
   
   
       23 . The rotary piston pump as claimed in  claim 1 , wherein the drive shaft, over its entire length, constitutes a shaft without cooling passage.