Rotary machine

Abstract

A rotary machine is provided with a plurality of impellers ( 3 ) which have a disk ( 31 ) rotating with a rotary shaft ( 2 ), the impellers being arranged side by side; and a casing ( 4 ) in which a casing flow passage ( 43 ) is formed to distribute a working medium therein. An impeller ( 3 ) disposed farthest away from a second side in the axial direction is disposed in a space communicating with an upstream part of the casing flow passage ( 43 ), and a protrusion portion ( 5 ) protruding from a back side ( 311 ) of the disk ( 31 ). The protrusion portion ( 5 ) has a sealing surface ( 51 ) which is formed to be parallel to an outer surface ( 21 ) of the rotary shaft ( 2 ) to seal a gap between itself and the casing ( 4 ), and a pressure receiving surface ( 51 ) which extends from the outer surface ( 21 ) to the sealing surface ( 51 ).

1 . A rotary machine comprising:
 a rotary shaft which rotates about an axis;   a plurality of impellers which have a disk rotating with the rotary shaft, and an internal flow passage formed to discharge a working fluid, which flows in from a first side in an axial direction in which the axis extends, toward an outer side in a radial direction, the plurality of impellers being disposed side by side in the axial direction; and   a casing in which a casing flow passage is formed to flow the working fluid from an impeller disposed on the first side in the axial direction to an impeller adjacent to a second side,   wherein among the plurality of impellers, an impeller disposed nearest to the second side in the axial direction has a protrusion portion which is disposed in a space communicating with an upstream part of the casing flow passage, which protrudes from a back side facing the second side of the disk in the axial direction, and which is formed integrally with the disk,   the protrusion portion has:   a sealing surface which is formed to be parallel to an outer surface of the rotary shaft to seal a gap in a radial direction between the protrusion portion and the casing, and   a pressure-receiving surface which extends from the outer surface of the rotary shaft to the sealing surface, and   the pressure-receiving surface has:   a main pressure-receiving surface formed by being connected to a second end portion of the sealing surface in the axial direction,   a first pressure-receiving surface which vertically extends radially outward from a second end portion in the axial direction of a through-hole which is formed in the disk and into which the rotary shaft is inserted, and   a second pressure-receiving surface inclined to face the outer surface of the rotary shaft on the radially outer side of the first pressure-receiving surface and connects the first pressure-receiving surface and the main pressure-receiving surface.   
     
     
         2 . The rotary machine according to  claim 1 , wherein a suction port is formed in the casing to allow the working fluid to flow into the casing flow passage from the outside, and the suction port and the space communicate with each other. 
     
     
         3 . The rotary machine according to  claim 1 , wherein the protrusion portion has a recess portion which is recessed from the pressure-receiving surface toward the first side in the axial direction on a radially inner side of the sealing surface. 
     
     
         4 . An impeller disposed nearest to a second side of a rotary machine in an axial direction, the rotary machine including, a rotary shaft which rotates about an axis, a plurality of impellers which have a disk rotating with the rotary shaft, and an internal flow passage formed to discharge a working fluid, which flows in from a first side in the axial direction in which the axis extends, toward an outer side in a radial direction, the plurality of impellers being disposed side by side in the axial direction, and a casing in which a casing flow passage is formed to circulate the working fluid from an impeller disposed on the first side in the axial direction to an impeller adjacent to the second side, the impeller comprising:
 a protrusion portion which protrudes from a back side facing the second side of the disk in the axial direction, which is integrally formed with the disk, and which is disposed in a space communicating with an upstream side of the casing flow passage,   wherein the protrusion portion has:   a sealing surface which is formed to be parallel to an outer surface of the rotary shaft to seal a gap in the radial direction between the protrusion portion and the casing, and   a pressure-receiving surface which extends from the outer surface of the rotary shaft to the sealing surface, and   the pressure-receiving surface has:   a main pressure-receiving surface formed by being connected to a second end portion of the sealing surface in the axial direction,   a first pressure-receiving surface which vertically extends radially outward from a second end portion in the axial direction of a through-hole which is formed in the disk and into which the rotary shaft is inserted, and   a second pressure-receiving surface inclined to face the outer surface of the rotary shaft on the radially outer side of the first pressure-receiving surface and connects the first pressure-receiving surface and the main pressure-receiving surface.