Impeller, rotary machine, and impeller manufacturing method

Abstract

An impeller includes: a disc having a disc shape; a plurality of blades formed on a surface facing a first side in an axial direction of the disc; and a cover surrounding the plurality of blades. The cover includes: an inner circumferential surface connected to the blades with a diameter decreasing from the second side toward a first side in the axial direction; and a distal end surface extending from an end portion of the inner circumferential surface on the first side in the axial direction toward the outside in a radial direction and facing the first side in the axial direction. A front edge portion extends from a boundary between the inner circumferential surface and the distal end surface toward the inside in the radial direction.

1 . An impeller comprising:
 a disc having a disc shape about an axis;   a plurality of blades formed on a surface facing a first side in an axial direction of the disc at intervals in a circumferential direction around the axis; and   a cover surrounding the plurality of blades from the first side in the axial direction, wherein   the cover includes:   an inner circumferential surface connected to the blades with a diameter decreasing from the second side toward a first side in the axial direction; and   a distal end surface extending from an end portion of the inner circumferential surface on the first side in the axial direction toward the outside in a radial direction and facing the first side in the axial direction, and   a front edge portion, which is an edge portion of the blade on the first side in the axial direction, extends from a boundary between the inner circumferential surface and the distal end surface toward the inside in the radial direction.   
     
     
         2 . The impeller according to  claim 1 , wherein the distal end surface has a convex curved surface disposed on the second side in the axial direction toward the inside in the radial direction. 
     
     
         3 . The impeller according to  claim 1 , wherein the front edge portion has a protruding edge portion protruding toward the first side in the axial direction on a radial outer side thereof. 
     
     
         4 . A rotary machine comprising an impeller according to  claim 1 . 
     
     
         5 . A method of manufacturing an impeller including:
 a disc having a disc shape about an axis;   a plurality of blades formed on a surface facing a first side in an axial direction of the disc at intervals in a circumferential direction around the axis; and   a cover surrounding the plurality of blades from the first side in the axial direction, wherein   the cover has:   an inner circumferential surface connected to the blade with a diameter decreasing from the second side toward the first side in the axial direction; and   a distal end surface extending from an end portion of the inner circumferential surface on the first side in the axial direction toward the outside in a radial direction and facing the first side in the axial direction, and   the method of manufacturing an impeller comprising:   a process of forming a front edge portion, which is an edge portion of the blade on the first side in the axial direction, to extend from a boundary between the inner circumferential surface and the distal end surface toward the inside in the radial direction.