Centrifugal compressor and geared centrifugal compressor

Abstract

A centrifugal compressor includes a rotation shaft that extends along an axis; an impeller that includes a disk fixed to the rotation shaft and protruding outward in a radial direction, a plurality of blades provided in a surface facing one side in an axial direction of the disk to be separated from each other in a circumferential direction, and a cover covering the blades from the one side in the axial direction; and a casing that includes a facing inner peripheral surface facing an outer peripheral surface of the cover in the impeller and covers the impeller from an outside. The facing inner peripheral surface includes a cylindrical inner peripheral surface that extends along the axis and an enlarged inner peripheral surface that is connected to another side of the cylindrical inner peripheral surface in the axial direction and extends outward in the radial direction toward the other side.

1 . A centrifugal compressor comprising:
 a rotation shaft that extends along an axis;   an impeller that includes:
 a disk fixed to the rotation shaft and protruding outward in a radial direction; 
 a plurality of blades provided in a surface facing one side in an axial direction of the disk to be separated from each other in a circumferential direction and 
 a cover covering the blades from the one side in the axial direction; and 
   a casing that includes a facing inner peripheral surface facing an outer peripheral surface of the cover in the impeller and covers the impeller from an outside,   wherein the facing inner peripheral surface includes:
 a cylindrical inner peripheral surface that extends along the axis; and 
   an enlarged inner peripheral surface that is connected to another side of the cylindrical inner peripheral surface in the axial direction and extends outward in the radial direction toward the other side,   wherein the centrifugal compressor further comprises a sealing portion that seals a gap between the enlarged inner peripheral surface and the outer peripheral surface of the cover, and   wherein the sealing portion is disposed in an area of 90% or less of a diameter dimension of the disk with reference to the axis.   
     
     
         2 . The centrifugal compressor according to  claim 1 ,
 wherein the sealing portion includes a plurality of sealing fins that are provided in the enlarged inner peripheral surface and extend in a direction from the enlarged inner peripheral surface toward the outer peripheral surface of the cover in the impeller.   
     
     
         3 . The centrifugal compressor according to  claim 1 ,
 wherein the sealing portion includes a plurality of sealing fins that are provided in the enlarged inner peripheral surface to extend in a direction from the enlarged inner peripheral surface toward an inside in the radial direction of the axis and to be arranged in the axial direction,   wherein a protrusion portion that protrudes from the outer peripheral surface of the cover and includes a sealing surface extending parallel to the axis is provided at a position corresponding to the sealing portion in the outer peripheral surface of the cover, and   wherein the sealing surface faces the plurality of sealing fins.   
     
     
         4 . The centrifugal compressor according to  claim 1 ,
 wherein the sealing portion includes a plurality of impeller side fins that are provided in a facing cover surface facing the enlarged inner peripheral surface in the cover and extend in a direction from the facing cover surface toward the enlarged inner peripheral surface.   
     
     
         5 . The centrifugal compressor according to  claim 4 , further comprising:
 an abradable portion that is provided in the enlarged inner peripheral surface and is formed of a material abradable when brought into contact with front ends of the impeller side fins.   
     
     
         6 . (canceled) 
     
     
         7 . The centrifugal compressor according to  claim 1 , further comprising:
 a back surface sealing portion that seals a gap between a surface of the disk facing the other side in the axial direction and the casing.   
     
     
         8 . A geared centrifugal compressor comprising:
 the centrifugal compressor according to  claim 1 ; and   a speed increasing transmission portion that includes a rotation driving shaft rotationally driven by an external driving source and an accommodation portion accommodating the rotation driving shaft and communicating with an inside of the casing, and transmits a rotation of the rotation driving shaft to the rotation shaft of the centrifugal compressor.   
     
     
         9 . The geared centrifugal compressor according to  claim 8 , further comprising:
 another centrifugal compressor that is disposed at an opposite side of the rotation shaft of the centrifugal compressor with the speed increasing transmission portion interposed therebetween, and is plane symmetric with the centrifugal compressor with reference to a reference plane orthogonal to the axis.