Machine, preferably a vacuum pump, with magnetic bearings

Abstract

The invention relates to a machine ( 1 ), comprising a stator and a rotor ( 2 ) which is mounted with radially stable and axially unstable magnetic bearings ( 3, 4 ). Said magnetic bearings ( 3, 4 ) each consist of concentrically arranged magnetic ring sets ( 5, 6; 7, 8 ) in which the stationary magnetic ring set ( 5 or 7 ) is situated inside and the rotating magnetic ring set ( 6 or 8 ) is situated outside. The machine also comprises means ( 21, 23, 24, 27 ) for regulating the axial position of the rotor ( 2 ). The aim of the invention is to simplify a machine of this type. To this end, one ( 4 ) of the two magnetic bearings ( 3, 4 ) is itself equipped with the axial regulation means and at least one coil ( 23 ) controlled by a position sensor ( 21 ) and pole components ( 24 ) surround the outer magnetic ring set ( 8 ) of the axially regulated bearing ( 4 ).

1 . Machine ( 1 ), comprising a stator and a rotor ( 2 ) which is mounted with radially stable and axially unstable magnetic bearings ( 3 ,  4 ), whereby the magnetic bearings ( 3 ,  4 ) each consist of concentrically arranged magnetic ring sets ( 5 ,  6 ;  7 ,  8 ) in which the stationary magnetic ring set ( 5  or  7 ) is situated inside and the rotating magnetic ring set ( 6  or  8 ) is situated outside as well as means ( 21 ,  23 ,  24 ,  27 ) for regulating the axial position of the rotor ( 2 ) wherein one ( 4 ) of the two magnetic bearings ( 3 ,  4 ) is itself equipped with the axial regulation means and at least one coil ( 23 ) is controlled by a position sensor ( 21 ) and pole components ( 24 ) surround the outer magnetic ring set ( 8 ) of the axially regulated bearing ( 4 ).  
     
     
         2 . Machine in accordance with  claim 1 , wherein the magnetic ring sets ( 5  to  8 ) consist of rings magnetised in the axial direction which are arranged over each other with changing poles, and where the ring sets ( 5 ,  6  resp.  7 ,  8 ) of a bearing ( 3 ,  4 ) repel each other.  
     
     
         3 . Machine in accordance with  claim 2 , wherein the cross section of the pole components ( 24 ) is designed to be U-shaped and where the face sides of the U-limbs of the pole components ( 24 ) face the outer magnetic ring set ( 8 ).  
     
     
         4 . Machine in accordance with  claim 3 , wherein the face sides of the U-limbs of the pole components ( 24 ) have a distance which corresponds approximately to the single or multiple axial distance of a magnetic ring and where the coils/yoke components are so arranged that the face sides of the U-limbs are arranged at the level of the centers of the magnetic rings.  
     
     
         5 . Machine in accordance with  claim 4  or  5 , wherein one or several coil(s) ( 23 ) with one, resp. one each U-shaped pole component ( 24 ) is/are provided.  
     
     
         6 . Machine in accordance with one of the claims  2  or  5 , wherein for n magnetic rings of the outer ring set ( 8 ) n−1 coils ( 23 ) are provided which are each encompassed by an arrangement of U-shaped pole components ( 24 ) and where the limbs of the U-shaped yoke components ( 24 ) are located approximately at the level of the centers of the magnetic rings.  
     
     
         7 . Machine in accordance with one of the above claims, wherein the number of the magnetic rings of the two ring sets of a magnetic bearing differ.  
     
     
         8 . Machine in accordance with  claim 7 , wherein the number of magnetic rings of the rotating magnetic-ring set ( 6 ,  8 ) is greater than the number of magnetic rings of the stationary pair of magnetic rings ( 5 ,  7 ).  
     
     
         9 . Machine in accordance with one of the above claims, wherein the magnetic rings of the ring sets ( 5 ,  6 ,  7 ,  8 ) are affixed in receptacles, where as the receptacle for the magnetic rings of the outer ring set ( 8 ) of the axially active bearing ( 4 ) a pipe-shaped reinforcement is employed which is affixed to a first section at the rotating system ( 2 ) and with a second section that carries the magnetic rings of the ring set ( 8 ).  
     
     
         10 . Machine in accordance with  claim 9 , wherein the reinforcement ( 14 ) also encompasses the armature ( 48 ) of a drive motor ( 46 ).  
     
     
         11 . Machine in accordance with  claim 2  and one the  claims 3  to  10 , wherein centrally arranged carriers ( 15 ,  16 ) are provided for the stationary magnetic-ring sets ( 5 ,  7 ) where one of the carriers ( 15 ,  16 ) is equipped with a central bore ( 19 ), where a shaft end ( 20 ) of the rotating system ( 2 ) penetrates the bore ( 19 ) and where an axial sensor ( 21 ) is related to the unoccupied face side of the shaft end ( 20 ).  
     
     
         12 . Machine in accordance with  claim 11 , wherein one of the carriers ( 15 ,  16 ) is axially adjustable.  
     
     
         13 . Machine in accordance with one of the above claims, wherein the diameters of the facing circumferential surfaces of the rings of a pair of ring sets ( 5 ,  6  resp.  7 ,  8 ) change in steps.  
     
     
         14 . Machine in accordance with one of the above claims, wherein at least between a part of the magnetic rings of the magnetic ring sets ( 5 ,  6 ,  7 ,  8 ) there are located spacing ring disks ( 31 ) made of a non-ferrite material.  
     
     
         15 . Machine in accordance with  claim 1 , wherein the material of the spacing disks ( 31 ) has a high electrical conductance.  
     
     
         16 . Machine in accordance with  claim 15 , wherein the circumferences of the spacing disks ( 31 ) close to the slot are reinforced.  
     
     
         17 . Machine in accordance with  claim 14 ,  15  or  16 , wherein the magnetic rings are encapsulated and where the layers of the encapsulation have the function of the spacing ring disks ( 31 ).  
     
     
         18 . Machine in accordance with  claim 14 ,  15  or  16 , wherein a sleeve ( 32 ) is assigned to the circumferential surfaces of the magnetic rings close to the slot.  
     
     
         19 . Machine in accordance with one of the above claims, wherein it is designed as a drag pump ( 1 ) and where the passive bearing ( 3 ) is located at the high-vacuum side, the axially active bearing ( 4 ) at the fore-vacuum side.  
     
     
         20 . Machine in accordance with  claim 19 , wherein a drive motor ( 46 ) with a can ( 49 ) is provided and where the can ( 49 ) penetrates the slot ( 28 ) of the axially active bearing ( 4 ).