Methods of controlling the instability in fluid film bearings

Abstract

A method of controlling the instability in fluid film bearings by using a magnetic bearing in combination with a fluid film bearing (whether it is a cylindrical journal bearing, an elliptic bearing, an offset-half bearing, a multi-lobe bearing, foil bearing or a tilting-pad bearing, does not really matter), wherein the fluid film bearing serves as the primary load carrying bearing and the magnetic bearing controls the instability of the fluid film bearing. This efficient combination results in bearings that can be used at high speeds without having neither stability nor reliability problems. An alternative method of controlling the instability in fluid film bearings is to disturb the flow in the axial direction, for example, a sleeve (journal) bearing can be manufactured such that the bearing axis is skewed with the shaft axis or a variable geometry bearing can be manufactured to allow for bearing angular misalignment.

1 . A method of controlling the instability in radial fluid film bearings, including fluid film bearings used in high speed rotor or shaft assemblies, the method comprising:
 using a magnetic bearing in combination with a radial fluid film bearing,
 wherein the radial fluid film bearing is adapted to serve as a primary load carrying bearing; and 
 wherein the magnetic bearing is adapted to serve as means for tangentially controlling the instability in the radial fluid film bearing, by withstanding tangential loads causing the instability arising from the radial fluid film bearing. 
   
   
   
       2 . The method according to  claim 1 , wherein the radial fluid film bearing is selected from the group consisting of cylindrical journal bearings, elliptic bearings, offset-half bearings, multi-lobe bearings, tilting-pad bearings, and foil bearings. 
   
   
       3 . The method according to  claim 1 , wherein the combination is in the form of two adjacent or non-adjacent bearings, one being the radial fluid film bearing and the other being the magnetic bearing. 
   
   
       4 . The method according to  claim 1 , wherein the combination is in the form of one integral bearing having the fluid film bearing within the magnetic bearing, such that a fluid for the fluid film bearing passes over a rotor of the magnetic bearing, and within a clearance between the rotor and a stator in the magnetic bearing. 
   
   
       5 - 28 . (canceled)