Scroll pump

Abstract

A non-contacting scroll pump, the non-contacting scroll pump comprising a housing, an orbiting scroll located within the housing, and a thrust bearing assembly located within the housing for axially supporting the orbiting scroll. The thrust bearing assembly comprises a first plate fixed to the orbiting scroll, a second plate spaced apart from the first plate, a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll, and a coupling structure extending axially between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure is engaged with the second plate, and wherein the coupling structure comprises a spring arranged to push the coupling structure against the second plate.

1 . A non-contacting scroll pump, the non-contacting scroll pump comprising:
 a housing;   an orbiting scroll located within the housing; and   a thrust bearing assembly located within the housing for axially supporting the orbiting scroll, wherein the thrust bearing assembly comprises:
 a first plate fixed to the orbiting scroll; 
 a second plate spaced apart from the first plate; 
 a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll; and 
 a coupling structure extending axially between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure is engaged with the second plate, and wherein the coupling structure comprises a spring arranged to push the coupling structure against the second plate. 
   
     
     
         2 . The non-contacting scroll pump of  claim 1 , wherein the coupling structure comprises a nut, wherein the nut is arranged such that loosening the nut causes the spring to push the coupling structure towards the second plate, and tightening the nut pulls the coupling structure in a direction away from the second plate. 
     
     
         3 . The non-contacting scroll pump of  claim 1 , wherein the spring is arranged to push the coupling structure against the second plate with a force between 500 N and 2000 N. 
     
     
         4 . The non-contacting scroll pump of  claim 1 , wherein the non-contacting scroll pump comprises three thrust bearing assemblies,
 wherein each of the three thrust bearing assemblies comprises:
 a first plate fixed to the orbiting scroll; 
 a second plate spaced apart from the first plate; 
 a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll; and 
 a coupling structure extending axially between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure is engaged with the second plate, and wherein the coupling structure comprises a spring arranged to push the coupling structure against the second plate, 
   wherein the three thrust bearing assemblies are evenly angularly distributed around the rotation axis of the orbiting scroll in a triangular formation.   
     
     
         5 . The non-contacting scroll pump of  claim 1 , further comprising:
 a first ball bearing cage sandwiched between the first plate and the second plate; and   a second ball bearing cage sandwiched between the first plate and the second plate,   wherein the first and second ball bearing cages house the ball bearing to constrain movement of the ball bearing.   
     
     
         6 . The non-contacting scroll pump of  claim 5 , wherein the first ball bearing cage is fixed to the first plate and the second ball bearing cage is fixed to the second plate. 
     
     
         7 . The non-contacting scroll pump of  claim 5 - or  6 , wherein the first and second ball bearing cages each comprise a hole, the hole of the first ball bearing cage overlapping with the hole of the second ball bearing cage, and
 wherein the ball bearing is accommodated within the overlapped holes of the ball bearing cages.   
     
     
         8 . The non-contacting scroll pump of  claim 1 , wherein the coupling structure is a pin. 
     
     
         9 . The non-contacting scroll pump of  claim 1 , wherein the coupling structure is for adjusting the axial position of the orbiting scroll. 
     
     
         10 . A vacuum pumping system comprising a plurality of vacuum pumps, wherein one of the vacuum pumps is the non-contacting scroll pump of  claim 1 . 
     
     
         11 . The use of the non-contacting scroll pump of  claim 1  to pump fluid. 
     
     
         12 . A method performed by a user on the non-contacting scroll pump of  claim 1 , the method comprising:
 loosening a nut of the coupling structure to cause the spring to push a spiral wall of the orbiting scroll into contact with a fixed scroll of the non-contacting scroll pump;   tightening the nut to pull the coupling structure away from the fixed scroll, thereby causing the orbiting scroll to be moved axially away from the fixed scroll;   while tightening the nut, using a sensor to track an amount of axial distance moved; and   stopping the tightening of the nut once a desired amount of axial distance has been reached.