Patent ID: 8360645

Claim:
A foil bearing that supports a cylindrical rotary shaft, the foil bearing comprising: (a) a hollow cylindrical outer ring supported by a fixed support surface, and that surrounds the rotary shaft with a predetermined gap therebetween; (b) a thin-film-shaped top foil that surrounds an outer surface of the rotary shaft, wherein one circumferential end of the thin-film shaped top foil is fixed to an inner surface of the outer ring; and (c) a back foil that is formed by a thin film sandwiched between the top foil and the inner surface of the outer ring, and the back foil elastically supports the top foil, wherein the back foil includes i. a support portion that comes into contact with the inner surface of the outer ring and is immovable in a circumferential direction; and ii. an elastic portion that is supported by the support portion, and the elastic portion is elastically bent in a radial direction by a surface pressure from the top foil.