Thrust foil bearing

Abstract

A thrust foil bearing includes a thrust member, and a foil member mounted to an end surface of the thrust member and having a thrust bearing surface that forms a thrust bearing gap. The foil member includes a foil that integrally includes a plurality of leaves each having a free end on one side in a circumferential direction and the thrust bearing surface, and a coupling portion for coupling the plurality of leaves to each other.

The invention claimed is: 
     
       1. A thrust foil bearing comprising:
 a thrust member; and 
 a foil member mounted to an end surface of the thrust member and having a thrust bearing surface that forms a thrust bearing gap, 
 wherein the foil member comprises a plurality of foils, each of the plurality of foils integrally comprising a plurality of leaves and a coupling portion for coupling the plurality of leaves to each other, 
 wherein each of the plurality of leaves comprises a free end on one side in a circumferential direction, and the thrust bearing surface, 
 wherein each of the plurality of foils has slits formed therein to form the plurality of leaves and the coupling portion, and 
 wherein the plurality of leaves of one of the plurality of foils are inserted through the slits of another of the plurality of foils so as to arrange the plurality of leaves of the one of the plurality of foils and the plurality of leaves of the another of the plurality of foils alternately to each other in the circumferential direction. 
 
     
     
       2. The thrust foil bearing according to  claim 1 , wherein the free end of each of the plurality of leaves comprises a radially outer edge inclined radially inward to a forward side in a rotational direction of a rotary member. 
     
     
       3. The thrust foil bearing according to  claim 2 , wherein the free ends of the plurality of leaves are arranged in a spiral pattern that feeds air into the thrust bearing gap. 
     
     
       4. The thrust foil bearing according to  claim 2 , wherein the free ends of the plurality of leaves are arranged in a herringbone pattern. 
     
     
       5. The thrust foil bearing according to  claim 1 , further comprising support portions arranged to respectively support the plurality of leaves from an opposite side with respect to the thrust bearing surface. 
     
     
       6. The thrust foil bearing according to  claim 1 , further comprising a coating provided on the thrust bearing surface of each of the plurality of leaves. 
     
     
       7. The thrust foil bearing according to  claim 1 , further comprising a coating provided on a surface on an opposite side with respect to the thrust bearing surface of each of the plurality of leaves. 
     
     
       8. The thrust foil bearing according to  claim 1 , wherein the thrust foil bearing is used for supporting a rotor of a gas turbine. 
     
     
       9. The thrust foil bearing according to  claim 1 , wherein the thrust foil bearing is used for supporting a rotor of a supercharger. 
     
     
       10. A foil bearing, comprising:
 a fixed member comprising a flat end surface;   a rotary member comprising a flat end surface opposed to the flat end surface of the fixed member;   a plurality of leaf foils formed separately from each other and the fixed member, each of the plurality of leaf foils being independently attached to the flat end surface of the fixed member, the plurality of leaf foils forming an equiangular array, each of the plurality of leaf foils comprising a free end on one side thereof in a circumferential direction, and each of the plurality of leaf foils having a bearing surface opposed to the flat end surface of the rotary member; and   a plurality of thrust bearing gaps, each of the plurality of thrust bearing gaps being formed between the bearing surface of each of the plurality of leaf foils and the flat end surface of the rotary member, and   wherein the free end of each of the plurality of leaf foils comprises:
 a plurality of cutout portions; and 
 a plurality of land portions that are continuous with the bearing surface, and 
   wherein the plurality of cutout portions and the plurality of land portions alternate with respect to each other.    
     
     
       11. The foil bearing according to claim 10, wherein the plurality of cutout portions and the plurality of land portions of the free end of each of the plurality of leaf foils form a zigzag shape.  
     
     
       12. The foil bearing according to claim 10, wherein the plurality of cutout portions and the plurality of land portions of the free end of each of the plurality of leaf foils form a corrugated shape.  
     
     
       13. The foil bearing according to claim 10, further comprising a coating provided on the bearing surfaces of the plurality of leaf foils.  
     
     
       14. The foil bearing according to claim 10, further comprising a coating provided on surfaces of the plurality of leaf foils that are on an opposite side of the plurality of leaf foils with respect to the bearing surfaces.  
     
     
       15. The foil bearing according to claim 13, wherein the coating comprises any one of a DLC film, a titanium aluminum nitride film, or a molybdenum disulfide film.  
     
     
       16. The foil bearing according to claim 13, wherein each of the plurality of thrust bearing gaps comprises:
 a small gap portion formed near the free end of the bearing surface of each of the leaf foils; and   a large gap portion formed at another side in the circumferential direction with respect to the small gap portion, and   wherein, as the rotary member rotates, a part of air in the small gap portions passes toward back sides of the plurality of leaf foils through the cutout portions.    
     
     
       17. A foil bearing, comprising:
 a fixed member comprising a cylindrical inner peripheral surface;   a rotary member comprising a cylindrical outer peripheral surface opposed to the cylindrical inner peripheral surface of the fixed member;   a plurality of leaf foils formed separately from each other and the fixed member, each of the plurality of leaf foils being independently attached to the cylindrical inner peripheral surface of the fixed member, the plurality of leaf foils forming an equiangular array, each of the plurality of leaf foils comprising a free end on one side thereof in a circumferential direction, and each of the plurality of leaf foils having a bearing surface opposed to the cylindrical outer peripheral surface of the rotary member; and   a plurality of radial bearing gaps, each of the plurality of radial bearing gaps being formed between the bearing surface of each of the plurality of leaf foils and the cylindrical outer peripheral surface of the rotary member, and   wherein the free end of each of the plurality of leaf foils comprises:   a plurality of cutout portions; and   a plurality of land portions that are continuous with the bearing surface,   wherein the plurality of cutout portions and the plurality of land portions alternate with respect to each other.    
     
     
       18. The foil bearing according to claim 17, wherein each of the plurality of radial bearing gaps comprises:
 a small gap portion formed near the free end of the bearing surface of each of the leaf foils; and   a large gap portion formed at another side in the circumferential direction with respect to the small gap portion, and   wherein, as the rotary member rotates, a part of air in the small gap portions passes toward back sides of the plurality of leaf foils through the cutout portions.