Compressor

Abstract

A compressor is provided that can avoid fretting damage to improve fatigue strength reliability. The present invention is characterized in that a portion on the circumferential outside and radial outside of a radial outside contact end portion 9 a with a dovetail portion 4 a is removed from a wheel 7. Specifically, the wheel 7 is formed with a groove portion 10 in an area that is located on the circumferential outside of the radial outside contact end portion 9 a of a blade securing portion 15 with the dovetail portion 4 a and that includes a radial outside of the contact end portion 9 a. Rigidity on the wheel side of the contact end portion 9 a between the dovetail portion 4 a and the wheel 7 is reduced to reduce the occurrence of stress, thereby avoiding the lowering of fatigue life reliability resulting from fretting.

What is claimed is: 
     
         1 . A compressor comprising:
 a rotor blade secured to an outer circumferential side of a wheel; and   a stator blade secured to an inner circumferential side of a casing incorporating the wheel;   wherein the rotor blade includes:   a blade portion;   a platform portion joined to a root side of the blade portion and having planes parallel to a centrifugal-force load direction of the blade portion; and   a dovetail portion which merges with the platform portion, is located radially inward of the platform portion and is increased in width outwardly from the parallel planes of the platform portion, the dovetail portion being fixedly inserted into a blade securing groove formed on the outer circumferential side of the wheel, and   wherein the wheel is formed with a groove portion or a hollow portion in an area that is located on a circumferential outside of a radial outside contact end portion of the blade securing groove with the dovetail portion and that includes a radial outside of the radial outside contact end portion.   
     
     
         2 . The compressor according to  claim 1 ,
 wherein the wheel is formed with the groove portion or the hollow portion in an area including a circumferential inside of a radial inside contact end portion of the blade securing groove with the dovetail portion.   
     
     
         3 . The compressor according to  claim 1 ,
 wherein the groove portion is formed by a first straight-line part extending circumferentially outward from the radial outside contact end portion, a second straight-line part extending radially outward, and a curved part connecting the first and second straight-line parts together.   
     
     
         4 . The compressor according to  claim 1 ,
 wherein the groove portion is formed such that a distance from the parallel plane of the platform portion is gradually increased as the groove portion goes toward the radial outside from the radial outside contact end portion.   
     
     
         5 . The compressor according to  claim 1 ,
 wherein the groove portion or the hollow portion is subjected to compressive residual stress by shot peening.   
     
     
         6 . The compressor according to  claim 1 ,
 wherein the groove portion or the hollow portion has a surface subjected to surface modification by friction stir.