Turbo type fluid machine

Abstract

A turbo type compressor of the present invention comprises a housing, a rotating shaft, and first and second impellers. The rotating shaft is supported by the housing to be rotatable around a rotational axis. A cylinder portion is provided on the rear end side of the rotating shaft. The rotating shaft is supported by a first radial foil bearing provided on the radially outer circumference of the cylinder portion and a second radial foil bearing provided on the radially inner circumference of the cylinder portion.

1 . A turbo type fluid machine comprising:
 a rotating shaft supported by a housing to be rotatable around a rotational axis; and   an impeller coupled to the rotating shaft, wherein   the turbo type fluid machine discharges fluid along with rotation of the impeller, wherein   the rotating shaft includes a cylinder portion, and   the rotating shaft is supported by a first radial foil bearing provided on a radially outer circumference of the cylinder portion and a second radial foil bearing provided on a radially inner circumference of the cylinder portion.   
     
     
         2 . The turbo type fluid machine according to  claim 1 , wherein
 the first radial foil bearing includes a first top foil and a first bump foil located on a radially outer circumference side of the first top foil and capable of elastically supporting the first top foil,   the first top foil includes, at one end, a first rotation stop portion for preventing the first top foil from rotating with respect to the housing,   the second radial foil bearing includes a second top foil and a second bump foil located on a radially inner circumference side of the second top foil and capable of elastically supporting the second top foil,   the second top foil includes, at one end, a second rotation stop portion for preventing the second top foil from rotating with respect to the housing, and   the rotational axis is arranged such that the rotational axis does not cross an imaginary straight line that connects the first rotation stop portion and the second rotation stop portion.   
     
     
         3 . The turbo type fluid machine according to  claim 1 , wherein
 the cylinder portion is provided at one end of the rotating shaft,   the housing includes a bottomed cylindrical portion and a convex portion projecting into the cylinder portion from a bottom surface of the bottomed cylindrical portion,   the first radial foil bearing is provided on a radially inner circumference of the bottomed cylindrical portion, and   the second radial foil bearing is provided on a radially outer circumference of the convex portion.   
     
     
         4 . The turbo type fluid machine according to  claim 3 , wherein
 the cylinder portion includes a disk-shaped first supported portion extending from one end of the rotating shaft in a direction orthogonal to the rotational axis and a cylindrical second supported portion extending further apart from the one end of the rotating shaft from an outer circumferential edge of the first supported portion in parallel with the rotational axis,   a first thrust foil bearing is provided on a surface of the first supported portion on the side of the rotating shaft, and   a second thrust foil bearing is provided on a surface of the first supported portion on the opposite side of the rotating shaft.