WO2014098417A1

WO2014098417A1 - Impeller assembly of fluid rotary machine

Info

Publication number: WO2014098417A1
Application number: PCT/KR2013/011579
Authority: WO
Inventors: Jong Kee Ahn
Original assignee: Samsung Techwin Co., Ltd
Priority date: 2012-12-18
Filing date: 2013-12-13
Publication date: 2014-06-26
Also published as: KR20140079194A; KR101612854B1

Abstract

An impeller assembly of a fluid rotary machine includes: a rotation shaft; a base part coupled to the rotation shaft and extending in a circumferential direction; a plurality of blades extending outward from the rotation shaft in radial directions, the blades being arranged around the rotation shaft and spaced apart from each other in the circumferential direction, the blades including narrowly stepped portions formed on end portions opposite to the base part; and a plurality of shroud plates disposed between the blades adjacent to each other, the shroud plates including edges placed on the stepped portions of the blades adjacent to each other, the edges being coupled to the stepped portions by welding.

Description

IMPELLER ASSEMBLY OF FLUID ROTARY MACHINE

Embodiments relates to an impeller assembly of a fluid rotary machine, and more particularly, to an impeller assembly in which an impeller and a shroud are combined as a unit for improving the efficiency of the impeller assembly.

Compressors or pumps used to compress fluid have a rotary machine structure having a rotary part.

In general, such a rotary machine includes an impeller as a rotary part to transfer rotational kinetic energy to fluid and thus to pressurize the fluid. Such an impeller includes a plurality of blades to guide flows of fluid and transfer energy to the fluid.

In addition, a shroud is disposed outside the impeller to form fluid passages together with the blades.

Generally, as the gaps between the shroud and the blades are narrow, the efficiency of a compressor increases, and thus a technique of combining an impeller and a shroud has recently been proposed for improving the efficiency of a compressor.

In a technique for manufacturing an impeller and a shroud by coupling the shroud to the impeller, a process such as casting, brazing, or electron beam welding is used to fix blades of the impeller to the shroud.

Japanese Patent Laid-open Publication No.: 2004-353608 discloses a technique for combining a shroud and an impeller by welding. In the disclosed technique, the impeller and the shroud are fixed to each other by brining the impeller and the shroud into contact with each other and simply welding the impeller and the shroud. However, according to the disclosed technique, while the impeller and the shroud are welded, the impeller and the shroud may be markedly deformed due to an excessive amount of welding heat.

A purpose of embodiments is to provide an impeller assembly of a fluid rotary machine, the impeller assembly including an impeller and a shroud combined as a unit for improving the efficiency of the fluid rotary machine.

Another purpose of the embodiments is to provide an impeller assembly of a fluid rotary machine, the impeller assembly being improved in the welding strength between an impeller and a shroud.

According to an aspect of the present invention, there is provided an impeller assembly of a fluid rotary machine, the impeller assembly including: a rotation shaft; a base part coupled to the rotation shaft and extending in a circumferential direction; a plurality of blades extending outward from the rotation shaft in radial directions, the blades being arranged on the base part around the rotation shaft and spaced apart from each other in the circumferential direction, the blades including narrowly stepped portions formed on end portions opposite to the base part; and a plurality of shroud plates disposed between the blades adjacent to each other, the shroud plates including edges placed on the stepped portions of the blades adjacent to each other, the edges being coupled to the stepped portions by welding.

A brazing filler may be applied to a surface portion of the shroud plates facing the base part and making contact with the blades, and the blades and the surface portion of the shroud plates making contact with the blades may be connected through a brazing process.

The stepped portions of the blades may extend outward from the rotation shaft in radial directions along at least one portion of the blades.

In the impeller assembly of the fluid rotary machine, the blades and the shroud plates are fixed to each other by a welding method satisfying precise tolerance requirements, and thus the gaps between the blades and the shroud plates may be kept as precise as that required in the design of the fluid rotary machine for improving the efficiency the fluid rotary machine.

In addition, since a welding process is performed in a state that the edges of the shroud plates are stably placed on the stepped portions of the blades, a large area may be welded. Therefore, during the welding process, cracking may be minimized in the coupled interfaces between the shroud plates and the blades.

Furthermore, since a brazing process is performed on contact surfaces between the blades and the shroud plates facing the base part in a state that the shroud plates and the blades are fixed to each other by welding, the inner sides of the shroud plates and the blades may be bonded together more stably.

FIG. 1 is a perspective view schematically illustrating assembling procedures of an impeller assembly of a fluid rotary machine according to an embodiment.

FIG. 2 is a schematic sectional view of the impeller assembly illustrated in FIG. 1.

Fig. 3 is a sectional view of the impeller assembly, taken along line III-III of Fig. 1.

FIG. 4 is a sectional view illustrating the impeller assembly of FIG. 1 after a welding process.

Hereinafter, the structure and operation of an impeller assembly of a fluid rotary machine will be described in detail with reference to the accompanying drawings according to embodiments. In the following description, the term "and/or" includes any and all combinations of one or more of the associated listed items.

FIG. 1 is a perspective view schematically illustrating assembling procedures of an impeller assembly of a fluid rotary machine according to an embodiment, and FIG. 2 is a schematic sectional view of the impeller assembly illustrated in FIG. 1.

Referring to FIGS. 1 and 2, the impeller assembly 100 of the fluid rotary machine of the embodiment includes an impeller 110 and a shroud 120.

In the embodiment shown in FIGS. 1 and 2, the rotary machine may be a compressor. However, the embodiment is not limited thereto. That is, in the embodiment, the rotary machine may be any kind of rotary machine in which the pressure and velocity of fluid can be changed by rotation of the impeller assembly. For example, in the embodiment, the term "rotary machine" is used as a comprehensive meaning including a pump, an air blower, etc.

The impeller 110 includes a rotation shaft 111, a base part 112 disposed around the outer side of the rotation shaft 111 and having an radial shape with an outer diameter increasing in a downward direction, and a plurality of blades 113 arranged on the base part 112 and spaced apart from each other in a circumferential direction.

The base part 112 may be coupled to an outer side of the rotation shaft 111 and may have a radial shape with an outer diameter increasing in a downward direction. The base part 112 is designed to have an inclined curved surface forming bottom surfaces of fluid passages, so as to make flows of fluid smooth and maximize energy transfer to the fluid.

The blades 113 are placed on the base part 112 to guide flows of fluid and transfer kinetic energy of the impeller 110 to the fluid. The blades 113 may be arranged around the rotation shaft 111 and spaced apart from each other at predetermined intervals. The blades 113 may be arranged on the base part 112 in a radial shape. As the blades 113 are rotated, fluid introduced through inlets 100a is compressed by a centrifugal force and is then discharged through outlets 100b.

The shroud 120 may have an approximate cylindrical shape with an opened upper end forming the inlets 100a and a portion radially expanding in a downward direction from the opened upper end along peripheral edges of the blades 113. The shroud 120 forms top surfaces of the fluid passages. That is, the shroud 120 constitutes the fluid passages together with the base part 112 and the blades 113.

The shroud 120 includes a plurality of shroud plates 120a. The shroud plates 120a are disposed between the blades 113 adjacent to each other. As shown in FIG. 1, after placing the shroud plates 120a between the blades 113, the shroud plates 120a and the blades 113 may be coupled together by welding.

With reference to FIG. 2, a process of compressing fluid by rotation of the impeller assembly 100 will now be described. For example, if the rotation shaft 111 is rotated, the impeller 110 and the shroud 120 are rotated together with the rotation shaft 111.

Fluid introduced through the inlets 100a of the impeller assembly 100 is compressed to a high pressure by a centrifugal force generated by rotational kinetic energy of the impeller assembly 100, and is then discharged through the outlets 100b. The fluid discharged from the impeller assembly 100 through the outlets 100b may be decelerated and pressurized to a required level of pressure while passing through a diffuser (not shown).

Fig. 3 is a sectional view of the impeller assembly 100, taken along line III-III of Fig. 1, and FIG. 4 is a sectional view illustrating the impeller assembly 100 of FIG. 1 after a welding process.

Hereinafter, a method of manufacturing the impeller assembly 100 will be described according to an embodiment with reference to FIGS. 3 and 4.

As components constituting the rotary machine, the blades 113 and the shroud plates 120a are prepared. As shown in FIG. 1, the blades 113, constituting the impeller 110 together with the rotation shaft 111 and the base part 112, are mounted on the base part 112 for coupling with the shroud plates 120a. However, embodiments are not limited thereto. That is, in other embodiments, the blades 113 may be coupled to the shroud plates 120a and may then be mounted on the base part 112.

The blades 113 and the shroud plates 120a may be formed of lightweight carbon steel or nonferrous metals such as aluminum. In the embodiment, as long as the blades 113 and the shroud plates 120a are formed of metallic materials, there are no other limitations on the materials thereof.

The blades 113 include narrowly stepped portions 113a formed on end portions opposite to the base part 112. The stepped portions 113a extend along the blades 113 in radial directions away from the rotation shaft 111 (refer to FIG 1).

Edges 120b of the shroud plates 120a are placed on the stepped portions 113a of the blades 113. Therefore, the shroud plates 120a may stably be arranged between the blades 113 adjacent to each other.

As shown in FIG. 1, the thicknesses of the shroud plates 120a may be complementarily engaged with the heights of the stepped portions 113a so that the shroud 120 may be formed by assembling the shroud plates 120a. For example, the shroud plates 120a may be welded with the blades 113 therebetween, and in this case, the number of the shroud plates 120a may be equal to the number of the blades 113.

After the shroud plates 120a are placed between the blades 113, the edges 120b of the shroud plates 120a and the stepped portions 113a of the blades 113 may be welded together to firmly fix the shroud plates 120a and the blades 113 to each other.

When the shroud plates 120a and the blades 113 are fixed to each other by welding, the strength of the welding is proportional to the strength of the basic materials and the welded area. In the above-described structure of the impeller assembly 100, since a welding process is performed in a state that the edges 120b of the shroud plates 120a are placed on the stepped portions 113a of the blades 113, a large area may be welded to improve the strength of the welding.

The welding process may be a high energy density welding process such as laser welding or electron beam welding. When shroud plates and blades are brought into contact with each other and are welded using a metallic material such as aluminum, if a laser or electron beam is used to form fillets, the shroud plates or blades may be melted by high energy of the laser or electron beam. Thus, required tolerances may not be satisfied, and thus an impeller assembly may not be manufactured in a designed shape. On the other hand, if welding is performed using a low level of energy, incomplete coupling defects may be present due to insufficient melting.

However, in the above-described structure of the impeller assembly 100, since a welding process is performed in a state that the edges 120b of the shroud plates 120a are stably placed on the stepped portions 113a of the blades 113, a large area may be welded. Therefore, during the welding process, cracking may be minimized in the coupled interfaces between the shroud plates 120a and the blades 113.

Referring to FIG. 4, a brazing filler 141 may be applied to surface portions of the shroud plates 120a facing the base part 112 and making contact with the blades 113, and the blades 113 and the surface portions of the shroud plates 120a making contact with the blades 113 may be connected through a brazing process.

The brazing process may be performed after the shroud plates 120a and the blades 113 are fixed to each other by welding. Brazing is a process for bonding basic materials together without damaging the basic materials by melting a filler having a melting point lower that those of the basic materials.

In a state that the shroud plates 120a and the blades 113 are fixed to each other by welding as described above, the brazing filler 141 may be applied to contact surfaces between the blades 113 and the shroud plates 120a facing the base part 112, and heat may be applied to such a degree as that the brazing filler 141 may be melted, so as to more stably bond the inner sides of the shroud plates 120a and the blades 113 with the melted brazing filler 141.

In the above-described impeller assembly 100, the blades 113 and the shroud plates 120a are fixed to each other by welding to satisfy precise tolerance requirements, and thus the gaps between the blades 113 and the shroud plates 120a may be kept as precise as that required in the design of the fluid rotary machine for improving the efficiency of the fluid rotary machine.

The above-described structures and effects of the embodiments are for illustrative purposes only, and it will be understood by those of ordinary skill in the art that various changes and equivalent other embodiments are possible. Therefore, the scope and spirit of the present invention should be defined by the following claims.

The embodiments may be applied to impeller assemblies of fluid rotary machines.

Claims

An impeller assembly of a fluid rotary machine, the impeller assembly comprising:

a rotation shaft;

a base part coupled to the rotation shaft and extending in a circumferential direction;

a plurality of blades extending outward from the rotation shaft in radial directions, the blades being arranged on the base part around the rotation shaft and spaced apart from each other in the circumferential direction, the blades comprising narrowly stepped portions formed on end portions opposite to the base part; and

a plurality of shroud plates disposed between the blades adjacent to each other, the shroud plates comprising edges placed on the stepped portions of the blades adjacent to each other, the edges being coupled to the stepped portions by welding.
The impeller assembly of claim 1, wherein a brazing filler is applied to a surface portion of the shroud plates facing the base part and making contact with the blades, and the blades and the surface portion of the shroud plates making contact with the blades are connected through a brazing process.
The impeller assembly of claim 1, wherein the stepped portions of the blades extend outward from the rotation shaft in radial directions along at least one portion of the blades.