WO2018162660A1 - A double-stage impeller arrangement for a double-stage centrifugal turbo-compressor - Google Patents

A double-stage impeller arrangement for a double-stage centrifugal turbo-compressor Download PDF

Info

Publication number
WO2018162660A1
WO2018162660A1 PCT/EP2018/055807 EP2018055807W WO2018162660A1 WO 2018162660 A1 WO2018162660 A1 WO 2018162660A1 EP 2018055807 W EP2018055807 W EP 2018055807W WO 2018162660 A1 WO2018162660 A1 WO 2018162660A1
Authority
WO
WIPO (PCT)
Prior art keywords
impeller
double
axial
stage
impellers
Prior art date
Application number
PCT/EP2018/055807
Other languages
French (fr)
Inventor
Patrice Bonnefoi
Julien COTE
Clément MARTIGNAGO
Yves Rosson
Stan VANDESTEENE
Original Assignee
Robert Bosch Gmbh
Danfoss Commercial Compressors
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch Gmbh, Danfoss Commercial Compressors filed Critical Robert Bosch Gmbh
Publication of WO2018162660A1 publication Critical patent/WO2018162660A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D17/08—Centrifugal pumps
    • F04D17/10—Centrifugal pumps for compressing or evacuating
    • F04D17/12—Multi-stage pumps
    • F04D17/122—Multi-stage pumps the individual rotor discs being, one for each stage, on a common shaft and axially spaced, e.g. conventional centrifugal multi- stage compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/08—Sealings
    • F04D29/10—Shaft sealings
    • F04D29/102—Shaft sealings especially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
    • F04D29/284—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
    • F04D29/287—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps with adjusting means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/60—Mounting; Assembling; Disassembling
    • F04D29/62—Mounting; Assembling; Disassembling of radial or helico-centrifugal pumps
    • F04D29/622—Adjusting the clearances between rotary and stationary parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/60—Mounting; Assembling; Disassembling
    • F04D29/62—Mounting; Assembling; Disassembling of radial or helico-centrifugal pumps
    • F04D29/624—Mounting; Assembling; Disassembling of radial or helico-centrifugal pumps especially adapted for elastic fluid pumps

Definitions

  • the present invention relates to a double-stage impeller arrangement for a double-stage centrifugal turbo-compressor, and to a double-stage centrifugal turbo- compressor including such a double-stage impeller arrangement.
  • a double-stage centrifugal turbo-compressor includes:
  • a double-stage impeller arrangement including:
  • an one-piece impeller member connected to the drive shaft and including a first impeller and a second impeller, each of the first and second impellers having a front-side and a back-side, the first and second impellers being arranged in a back-to-back configuration
  • inter-stage sealing device provided between the first and second impellers, the inter-stage sealing device including two separated sealing members each having a half-disc shape and being at least partially arranged within the radial annular groove.
  • inter-stage sealing device may lead to undesirable fluid leakage particularly between the sealing members. Therefore the manufacture of the above-mentioned inter-stage sealing device requires a high level of machining accuracy in order to limit said undesirable fluid leakage. Otherwise, the control of the sealing between the two stages of the above-mentioned double-stage centrifugal turbo-compressor is difficult due to said configuration of the inter-stage sealing device.
  • inter-stage sealing device requires re- machining of the sealing members depending of the axial gaps required between the two stages of the centrifugal turbo-compressor, and particularly between the backsides of the first and second impellers and the sealing members.
  • inter-stage sealing device complicates the manufacturing of the double-stage impeller arrangement, and increases the manufacturing cost of the double-stage impeller arrangement.
  • the configuration of the one-piece impeller member and of the inter-stage sealing device complicates the assembling the double-stage centrifugal turbo-compressor.
  • the positioning of the two separated sealing members within the radial annular groove requires the use of a specific tool.
  • Such a specific tool is also used to keep the two separated sealing members concentric to the longitudinal axis of the drive shaft until the attachment of said sealing members to a stationary part of the double-stage centrifugal turbo-compressor.
  • Another object of the present invention is to provide a robust, efficient and easy to manufacture double-stage impeller arrangement.
  • such a double-stage impeller arrangement includes:
  • first impeller and second impeller each of the first and second impellers having a front-side and a back-side, the first and second impellers being configured to be connected to a drive shaft of the double-stage centrifugal turbo- compressor and being arranged in a back-to-back configuration
  • the second impeller is distinct and separated from the first impeller so as to enable an adjustment of an axial distance between the back- sides of the first and second impellers
  • the inter-stage sealing device includes a one-piece sealing member having an annular disc shape and being at least partially arranged within the radial annular groove.
  • the first and second impellers are made from two separate and distinct pieces.
  • Such a configuration of the inter-stage sealing device simplifies its manufacturing and reduces the level of machining accuracy which is needed to manufacture it, while substantially reducing undesirable fluid leakage through the inter-stage sealing device and thus facilitating the control of the sealing between the two stages of a double-stage centrifugal turbo- compressor including the double-stage impeller arrangement according to the present invention.
  • Such a configuration of the inter-stage sealing device also reduces the cost for manufacturing the double-stage impeller arrangement.
  • first and second impellers are made from two separate and distinct pieces allows an adjustment of the axial distance between the back-sides of the first and second impellers during assembly of the double-stage impeller arrangement, and thus of the axial gaps required between the back-sides of the first and second impellers and the one-piece sealing member, without requiring re-machining of the sealing member.
  • two single stage impellers are easier to machine than a one- piece double stage impeller. Furthermore a better finish can be achieved especially on the back-sides of the first and second impellers when the latter are separately manufactured. Consequently, such a configuration of the first and second impellers improves the accuracy of the double-stage impeller arrangement according to the present invention and also reduces the manufacturing cost of the latter.
  • the inter-stage sealing device is made in one-piece and that the first and second impellers are made from two separate and distinct pieces, new sealing designs are now achievable for providing a labyrinth seal between the inner peripheral surface of the sealing member and a circumferential bottom surface of the radial annular groove, and between the axial wall surfaces of the one-piece sealing member and the back-sides of the first and second impellers.
  • the double-stage impeller arrangement may also include one or more of the following features, taken alone or in combination.
  • the first and second impellers are configured to be separately and/or independently connected to the drive shaft.
  • the one-piece sealing member comprises a central annular sealing portion having a first axial wall surface and a second axial wall surface opposite to the first axial wall surface, the first axial wall surface and the back-side of the first impeller defining a first axial gap and the second axial wall surface and the back-side of the second impeller defining a second axial gap.
  • the one-piece sealing member further comprises an outer annular sealing portion, the outer annular sealing portion having a thickness higher than a thickness of the central annular sealing portion.
  • the double-stage impeller arrangement further includes a labyrinth seal configured to minimize or control fluid flow across the labyrinth seal, the labyrinth seal being at least partially formed by an inner peripheral surface of the one-piece sealing member and a circumferential bottom surface of the radial annular groove.
  • the labyrinth seal includes at least one annular sealing groove configured to extend substantially coaxially with the drive shaft and provided on an axial wall surface of the one-piece sealing member or on the back-side of one of the first and second impellers, and at least one annular sealing rib provided on the back-side of one of the first and second impellers or on said axial wall surface of the one-piece sealing member, the at least one annular sealing groove being configured to cooperate with the at least one annular sealing rib.
  • the labyrinth seal includes:
  • At least one first annular sealing groove configured to extend substantially coaxially with the drive shaft and provided on a first axial wall surface of the one-piece sealing member or on the back-side of the first impeller, and at least one first annular sealing rib provided on the back-side of the first impeller or on said first axial wall surface of the one-piece sealing member, the at least one first annular sealing groove being configured to cooperate with the at least one first annular sealing rib, and/or
  • At least one second annular sealing groove configured to extend substantially coaxially with the drive shaft and provided on a second axial wall surface of the one-piece sealing member or on the back-side of the second impeller, and at least one second annular sealing rib provided on the back-side of the second impeller or on said second axial wall surface of the one-piece sealing member, the at least one second annular sealing groove being configured to cooperate with the at least one second annular sealing rib.
  • the first impeller includes an axial bore configured to firmly receive an axial end portion of the drive shaft of the double-stage centrifugal turbo-compressor.
  • the axial bore extends along the entire axial length of the first impeller.
  • the axial bore extends along a part of the axial length of the first impeller, and is thus a blind axial bore.
  • one of the first and second impellers includes an axial mounting portion and the other of the first and second impellers includes an axial receiving hole emerging in the back-side of said other of the first and second impellers, the axial mounting portion extending at least partially within the axial receiving hole and being firmly mounted in the axial receiving hole.
  • the circumferential bottom surface of the radial annular groove is defined by the axial mounting portion.
  • the axial mounting portion partially defines the axial bore.
  • the first impeller includes the axial mounting portion and the second impeller includes the axial receiving hole, the axial mounting portion including a longitudinal hole having a first hole end emerging in the axial bore of the first impeller and a second hole end emerging in the axial receiving hole.
  • the longitudinal hole is configured to extend coaxially with the drive shaft. The provision of the longitudinal hole ensures a secure attachment of the second impeller to the first impeller, and particularly a better shrink fit between the first and second impeller, while limiting deformation of functional surfaces (blade and sealing geometry) of the second impeller. Indeed, during assembly of the axial mounting portion within the axial receiving hole of the second impeller, the longitudinal hole allows deformation of the axial mounting portion of the first impeller towards its longitudinal axis and thus limits expansion of the outer diameter of the second impeller.
  • such a longitudinal hole ensures a discharge of the air which is confined between the end portion of the drive shaft and the axial bore of first impeller during the mounting of the end portion of the drive shaft in said axial bore, and thus facilitates the attachment of the first impeller to the drive shaft.
  • the second impeller is firmly connected to the axial mounting portion of the first impeller, for example by press-fit or shrink-fit, and advantageously by heat shrink fit, i.e. by heat shrinking.
  • the axial receiving hole extends along the entire axial length of the second impeller.
  • an end portion of the axial mounting portion projects from a front end of the second impeller.
  • the end portion of the axial mounting portion is rounded.
  • the second impeller includes an axial tubular portion extending from the back-side of the second impeller and around the axial mounting portion provided on the first impeller.
  • the axial tubular portion partially defines the axial receiving hole.
  • the circumferential bottom surface of the radial annular groove is defined by the axial tubular portion.
  • the first impeller includes an axial annular groove emerging in the back-side of the first impeller, the axial tubular portion of the second impeller extending partially in the axial annular groove.
  • the first impeller includes the axial receiving hole and the second impeller includes the axial mounting portion.
  • the second impeller includes a tubular mounting portion configured to be firmly and directly connected to the drive shaft, for example by press-fit or shrink-fit.
  • the tubular mounting portion of the second impeller is configured to be firmly and directly connected to the end portion of the drive shaft.
  • the tubular mounting portion of the second impeller axially extends from the back-side of the second impeller.
  • the circumferential bottom surface of the radial annular groove is defined by the tubular mounting portion.
  • the first impeller at least partially defines an axial annular groove emerging in the back-side of the first impeller, the tubular mounting portion of the second impeller extending partially in said axial annular groove.
  • the present invention also relates to a double-stage centrifugal turbo- compressor including a drive shaft and a double-stage impeller arrangement according to any one of claims 1 to 6, the first and second impellers being connected to the drive shaft.
  • the double-stage centrifugal turbo-compressor further includes a thrust bearing arrangement configured to limit an axial movement of the drive shaft during operation.
  • the double- stage centrifugal turbo-compressor may further include a radial bearing arrangement configured to rotatably support the drive shaft.
  • the double-stage centrifugal turbo-compressor further includes a driving device configured to drive in rotation the drive shaft about a rotation axis, the thrust bearing arrangement being located between the driving device and the first impeller.
  • the radial bearing arrangement is also located between the driving device and the first impeller.
  • the present invention further relates to a method for assembling a double-stage centrifugal turbo-compressor including the following steps:
  • the present invention also relates to a method for assembling a double- stage centrifugal turbo-compressor including the following steps:
  • Figure 1 is a longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a first embodiment of the invention.
  • Figure 2 is an enlarged longitudinal sectional view of the double-stage centrifugal turbo-compressor of figure 1.
  • Figure 3 is a partial exploded perspective view of the double-stage centrifugal turbo-compressor of figure 1.
  • Figure 4 is an enlarged longitudinal sectional view of details of the double-stage centrifugal turbo-compressor of figure 1.
  • Figure 5 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a second embodiment of the invention.
  • Figure 6 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a third embodiment of the invention.
  • Figure 7 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a fourth embodiment of the invention.
  • Figure 8 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a fifth embodiment of the invention.
  • Figure 9 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a sixth embodiment of the invention.
  • Figures 10 and 11 are partial longitudinal sectional views showing various steps for assembling the double-stage centrifugal turbo-compressor according to the sixth embodiment of the invention.
  • Figure 12 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a seventh embodiment of the invention.
  • Figure 13 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a eighth embodiment of the invention.
  • Figures 1 to 4 represent a double-stage centrifugal turbo-compressor 2 according to a first embodiment of the invention.
  • the double-stage centrifugal turbo-compressor 2 includes a casing 3, and a drive shaft 4 rotatably arranged within the casing 3 and extending along a longitudinal axis A.
  • the drive shaft 4 includes a first axial end portion 5, a second axial end portion 6 opposite to the first axial end portion 5, and an intermediate portion 7 arranged between the first and second end axial portions 5, 6.
  • the double-stage centrifugal turbo-compressor 2 further includes a first compression stage 8 and a second compression stage 9 configured to compress a refrigerant.
  • the first compression stage 8 includes a fluid inlet 11 and a fluid outlet 12, while the second compression stage 9 includes a fluid inlet 13 and a fluid outlet 14, the fluid outlet 12 of the first compression stage 8 being fluidly connected to the fluid inlet 13 of the second compression stage 9.
  • the first and second compression stages 8, 9 are partially defined by a double-stage impeller arrangement 17.
  • the double-stage impeller arrangement 17 includes a first impeller 18 and a second impeller 19 which are connected to the first axial end portion 5 of the drive shaft 4 and which extend coaxially with the drive shaft 4.
  • the first impeller 18 includes an axial bore 20 emerging in the front end of the first impeller 18 and configured to firmly receive the first axial end portion 5 of the drive shaft 4.
  • the axial bore 20 of the first impeller 18 extends along the entire axial length of the first impeller 18.
  • Each of the first and second impellers 18, 19 includes a front-side 21, 22 equipped with a plurality of blades 23, 24 configured to accelerate, during rotation of the drive shaft 4, the refrigerant entering the respective one of the first and second compression stages 8, 9, and to deliver the accelerated refrigerant to a diffuser arranged at the radial outside edge of the respective one of the first and second impellers 18, 19.
  • Each of the first and second impellers 18, 19 also includes a back-side 25, 26 extending substantially perpendicularly to the drive shaft 4.
  • the first and second impellers 18, 19 are arranged in a back-to-back configuration, so that the directions of fluid flow at the flow inlet 11, 13 of the first and second compression stages 8, 9 are opposite to each other.
  • the second impeller 19 is distinct and separated from the first impeller 18 so as to enable notably an adjustment of the axial distance between the back-sides 25, 26 of the first and second impellers 18, 19 during assembly of the double-stage impeller arrangement 17.
  • the second impeller 19 includes a tubular mounting portion 27 axially extending from the back-side 26 of the second impeller 19 and firmly and directly connected to the first end portion 5 of the drive shaft 4, for example by press-fit or shrink-fit.
  • the first impeller 18 and the drive shaft 4 define an axial annular groove 28 emerging in the back-side 25 of the first impeller 18, and the tubular mounting portion 27 extends partially in the axial annular groove 28.
  • the double-stage impeller arrangement 17 also includes a radial annular groove 29 formed between the back-sides 25, 26 of the first and second impellers 18, 19.
  • the circumferential bottom surface 30 of the radial annular groove 29 is defined by the tubular mounting portion 27.
  • the double-stage impeller arrangement 17 further includes an interstage sealing device provided between the first and second impellers 18, 19.
  • the inter- stage sealing device includes a one-piece sealing member 32 extending substantially perpendicularly to the drive shaft 4 and at least partially arranged within the radial annular groove 29.
  • the one-piece sealing member 32 is stationary and has an annular disc shape.
  • the one-piece sealing member 32 has an inner peripheral surface 33 and an outer peripheral surface 34.
  • the one-piece sealing member 32 comprises a central annular sealing portion 32.1 arranged within the radial annular groove 29 and an outer annular sealing portion 32.2 extending outside the radial annular groove 29.
  • the outer annular sealing portion 32.2 may have a thickness higher than the thickness of the central annular sealing portion 32.1.
  • the central annular sealing portion 32.1 has a first axial wall surface 35 and a second axial wall surface 36 opposite to the first axial wall surface 35.
  • the first axial wall surface 35 and the back-side 25 of the first impeller 18 define a first axial gap
  • the second axial wall surface 36 and the back-side 26 of the second impeller 19 define a second axial gap.
  • the double-stage impeller arrangement 17 further includes a labyrinth seal 37 provided between the first and second compressor stages 8, 9 and in the radial annular groove 29.
  • the labyrinth seal 37 is configured to minimize or control fluid flow across the labyrinth seal 37, and particularly from the second compression stage 9 to the first compression stage 8.
  • the labyrinth seal 37 is advantageously formed by the inner peripheral surface 33 of the one-piece sealing member 32 and the circumferential bottom surface 30 of the radial annular groove 29.
  • the labyrinth seal 37 may be formed, for example, by a succession of annular stationary steps formed on the inner peripheral surface 33 of the one-piece sealing member 32, and by a succession of annular rotary steps formed on the circumferential bottom surface 30 of the radial annular groove 29.
  • the labyrinth seal 37 may also be formed by a circumferential protrusion extending from the circumferential bottom surface 30 of the radial annular groove 29, and by an annular recess provided in the inner peripheral surface 33 of the one-piece sealing member 32 and receiving the circumferential protrusion.
  • the double-stage centrifugal turbo-compressor 2 further includes an electric motor 38 configured to drive in rotation the drive shaft 4 about the longitudinal axis A.
  • the double-stage centrifugal turbo-compressor 2 further includes a thrust bearing arrangement 39, also named axial bearing arrangement, configured to limit an axial movement of the drive shaft 4 during operation.
  • the thrust bearing arrangement 39 may be a fluid thrust bearing arrangement, and for example a gas thrust bearing arrangement.
  • the thrust bearing arrangement 39 may include an annular thrust bearing member 40 arranged on the outer surface of the intermediate portion 7 of the drive shaft 4, and located between the electric motor 38 and the first compression stage 8.
  • the thrust bearing member 40 may be integrally formed with the drive shaft 4, or may be secured to the latter.
  • the double-stage centrifugal turbo-compressor 2 may also include a radial bearing arrangement configured to rotatably support the drive shaft 4.
  • the radial bearing arrangement may include a radial bearing surrounding the drive shaft 4 and configured to cooperate with the outer surface of the drive shaft 4.
  • the radial bearing may be a fluid radial bearing, and for example a gas radial bearing.
  • the radial bearing may extend along a part of the intermediate portion 7 of the drive shaft 4.
  • the radial bearing arrangement may include a plurality of radial bearings distributed along the axial length of the drive shaft 4.
  • Figure 5 represents a double-stage centrifugal turbo-compressor 2 according to a second embodiment of the invention which differs from the first embodiment shown on figures 1 to 4 notably in that the second impeller 19 includes an axial receiving hole 41, which may be blind, emerging in the back-side 26 of the second impeller 19 and in that the first impeller 18 includes an axial mounting portion 42 extending at least partially within the axial receiving hole 41 and being firmly mounted in the axial receiving hole 41.
  • the second impeller 19 is firmly connected to the axial mounting portion 42 of the first impeller 18, for example by press-fit or shrink-fit.
  • the axial mounting portion 42 includes a longitudinal hole 43 having a first hole end 43.1 emerging in the axial bore 20 of the first impeller 18 and a second hole end 43.2 emerging in the axial receiving hole 41.
  • the longitudinal hole 43 extends coaxially with the drive shaft 4.
  • the circumferential bottom surface 30 of the radial annular groove 29 is defined by the axial mounting portion 42, and the axial bore 20 of the first impeller 18 is blind and thus extends along only a part of the axial length of the first impeller 18.
  • the axial mounting portion 42 may partially define the axial bore 20.
  • Figure 6 represents a double-stage centrifugal turbo-compressor 2 according to a third embodiment of the invention which differs from the second embodiment shown on figure 5 notably in that the axial receiving hole 41 extends along the entire axial length of the second impeller 19 and in that an end portion of the axial mounting portion 42 projects from a front end 42.1 of the second impeller 19.
  • Figure 7 represents a double-stage centrifugal turbo-compressor 2 according to a fourth embodiment of the invention which differs from the second embodiment shown on figure 5 notably in that the second impeller 19 includes an axial tubular portion 44 extending from the back-side 26 of the second impeller 19 and around the axial mounting portion 42 of the first impeller 18.
  • the axial tubular portion 44 partially defines the axial receiving hole 41, and the circumferential bottom surface 30 of the radial annular groove 29 is defined by the axial tubular portion 44.
  • Figure 8 represents a double-stage centrifugal turbo-compressor 2 according to a fifth embodiment of the invention which differs from the fourth embodiment shown on figure 7 in that the first impeller 18 includes an axial annular groove 45 emerging in the back-side 25 of the first impeller 18 and in that the axial tubular portion 44 of the second impeller 19 extends partially in the axial annular groove 45.
  • Figures 9 to 11 represent a double-stage centrifugal turbo-compressor 2 according to a sixth embodiment of the invention which differs from the second embodiment shown on figure 5 notably in that the second impeller 19 includes the axial mounting portion 42 and that the first impeller 18 includes the axial receiving hole 41.
  • the axial receiving hole 41 is formed by the axial bore 20.
  • first and second impellers 18, 19 for example by heat shrink-fit (the first impeller 18 being heated up and the second impeller 19, at ambient temperature, being inserted into the axial receiving hole 41 of the first impeller 18), with the one-piece sealing member 32 in place between the first and second impellers 18, 19;
  • the method for assembling the double-stage centrifugal turbo-compressor 2 according to the sixth embodiment of the invention includes the following steps:
  • such a pre-assembly step avoids using cold shrink fit process, which is a difficult and expensive assembly process, to insert the second impeller 19 into the first impeller 18.
  • Figure 12 represents a double-stage centrifugal turbo-compressor 2 according to a seventh embodiment of the invention which differs from the first embodiment notably in that the labyrinth seal 37 is formed by a plurality of concentric annular sealing grooves 46, 47 respectively formed on the first and second axial wall surfaces 35, 36 of the one-piece sealing member 32, and by a succession of concentric annular sealing ribs 48, 49 respectively formed on the back-sides 25, 26 of the first and second impellers 18, 19.
  • Figure 13 represents a double-stage centrifugal turbo-compressor 2 according to a eighth embodiment of the invention which differs from the first embodiment notably in that the labyrinth seal 37 is formed by two concentric annular sealing grooves 51, 52 respectively formed on the back-sides 25, 26 of the first and second impellers 18, 19, and by two concentric annular sealing ribs 53, 54 respectively formed on the first and second axial wall surfaces 35, 36 of the one-piece sealing member 32.

Abstract

The double-stage impeller arrangement (17) includes a first impeller (18) and a second impeller (19), each of the first and second impellers (18, 19) having a front-side (21, 22) and a back-side (25, 26), the first and second impellers (18, 19) being configured to be connected to a drive shaft (4) of the double-stage centrifugal turbo-compressor (2) and being arranged in a back-to-back configuration; a radial annular groove formed between the back-sides (25, 26) of the first and second impellers (18, 19); and an inter-stage sealing device provided between the first and second impellers (18, 19). The second impeller (19) is distinct and separated from the first impeller (18) so as to enable an adjustment of an axial distance between the back-sides (25, 26) of the first and second impellers (18, 19), and the inter-stage sealing device includes a one-piece sealing member (32) having an annular disc shape and being at least partially arranged within the radial annular groove.

Description

Title:
A double-stage impeller arrangement for a double-stage centrifugal turbo-compressor Field of the invention
The present invention relates to a double-stage impeller arrangement for a double-stage centrifugal turbo-compressor, and to a double-stage centrifugal turbo- compressor including such a double-stage impeller arrangement.
Background of the invention
As known, a double-stage centrifugal turbo-compressor includes:
- a casing,
- a drive shaft rotatably arranged within the casing and extending along a longitudinal axis,
- a double-stage impeller arrangement including:
- an one-piece impeller member connected to the drive shaft and including a first impeller and a second impeller, each of the first and second impellers having a front-side and a back-side, the first and second impellers being arranged in a back-to-back configuration,
- a radial annular groove formed between the back-sides of the first and second impellers, and
- an inter-stage sealing device provided between the first and second impellers, the inter-stage sealing device including two separated sealing members each having a half-disc shape and being at least partially arranged within the radial annular groove.
Such a configuration of the inter-stage sealing device may lead to undesirable fluid leakage particularly between the sealing members. Therefore the manufacture of the above-mentioned inter-stage sealing device requires a high level of machining accuracy in order to limit said undesirable fluid leakage. Anyway, the control of the sealing between the two stages of the above-mentioned double-stage centrifugal turbo-compressor is difficult due to said configuration of the inter-stage sealing device.
Further such a configuration of the inter-stage sealing device requires re- machining of the sealing members depending of the axial gaps required between the two stages of the centrifugal turbo-compressor, and particularly between the backsides of the first and second impellers and the sealing members. Thus, such a configuration of the inter-stage sealing device complicates the manufacturing of the double-stage impeller arrangement, and increases the manufacturing cost of the double-stage impeller arrangement.
Moreover, the configuration of the one-piece impeller member and of the inter-stage sealing device complicates the assembling the double-stage centrifugal turbo-compressor. Particularly, the positioning of the two separated sealing members within the radial annular groove requires the use of a specific tool. Such a specific tool is also used to keep the two separated sealing members concentric to the longitudinal axis of the drive shaft until the attachment of said sealing members to a stationary part of the double-stage centrifugal turbo-compressor.
Summary of the invention
It is an object of the present invention to provide an improved double- stage impeller arrangement which can overcome the drawbacks encountered in conventional double-stage impeller arrangement.
Another object of the present invention is to provide a robust, efficient and easy to manufacture double-stage impeller arrangement.
According to the invention such a double-stage impeller arrangement includes:
- a first impeller and a second impeller, each of the first and second impellers having a front-side and a back-side, the first and second impellers being configured to be connected to a drive shaft of the double-stage centrifugal turbo- compressor and being arranged in a back-to-back configuration,
- a radial annular groove formed between the back-sides of the first and second impellers, and
- an inter-stage sealing device provided between the first and second impellers,
characterized in that the second impeller is distinct and separated from the first impeller so as to enable an adjustment of an axial distance between the back- sides of the first and second impellers, and in that the inter-stage sealing device includes a one-piece sealing member having an annular disc shape and being at least partially arranged within the radial annular groove. In other words, the first and second impellers are made from two separate and distinct pieces.
Such a configuration of the inter-stage sealing device, and particularly the fact that it is made in one-piece, simplifies its manufacturing and reduces the level of machining accuracy which is needed to manufacture it, while substantially reducing undesirable fluid leakage through the inter-stage sealing device and thus facilitating the control of the sealing between the two stages of a double-stage centrifugal turbo- compressor including the double-stage impeller arrangement according to the present invention. Such a configuration of the inter-stage sealing device also reduces the cost for manufacturing the double-stage impeller arrangement.
Further the fact that the first and second impellers are made from two separate and distinct pieces allows an adjustment of the axial distance between the back-sides of the first and second impellers during assembly of the double-stage impeller arrangement, and thus of the axial gaps required between the back-sides of the first and second impellers and the one-piece sealing member, without requiring re-machining of the sealing member.
Moreover, two single stage impellers are easier to machine than a one- piece double stage impeller. Furthermore a better finish can be achieved especially on the back-sides of the first and second impellers when the latter are separately manufactured. Consequently, such a configuration of the first and second impellers improves the accuracy of the double-stage impeller arrangement according to the present invention and also reduces the manufacturing cost of the latter.
In addition, due to the fact that the inter-stage sealing device is made in one-piece and that the first and second impellers are made from two separate and distinct pieces, new sealing designs are now achievable for providing a labyrinth seal between the inner peripheral surface of the sealing member and a circumferential bottom surface of the radial annular groove, and between the axial wall surfaces of the one-piece sealing member and the back-sides of the first and second impellers.
The double-stage impeller arrangement may also include one or more of the following features, taken alone or in combination.
According to an embodiment of the invention, the first and second impellers are configured to be separately and/or independently connected to the drive shaft.
According to an embodiment of the invention, the one-piece sealing member comprises a central annular sealing portion having a first axial wall surface and a second axial wall surface opposite to the first axial wall surface, the first axial wall surface and the back-side of the first impeller defining a first axial gap and the second axial wall surface and the back-side of the second impeller defining a second axial gap.
According to an embodiment of the invention, the one-piece sealing member further comprises an outer annular sealing portion, the outer annular sealing portion having a thickness higher than a thickness of the central annular sealing portion.
According to an embodiment of the invention, the double-stage impeller arrangement further includes a labyrinth seal configured to minimize or control fluid flow across the labyrinth seal, the labyrinth seal being at least partially formed by an inner peripheral surface of the one-piece sealing member and a circumferential bottom surface of the radial annular groove.
According to an embodiment of the invention, the labyrinth seal includes at least one annular sealing groove configured to extend substantially coaxially with the drive shaft and provided on an axial wall surface of the one-piece sealing member or on the back-side of one of the first and second impellers, and at least one annular sealing rib provided on the back-side of one of the first and second impellers or on said axial wall surface of the one-piece sealing member, the at least one annular sealing groove being configured to cooperate with the at least one annular sealing rib.
According to an embodiment of the invention, the labyrinth seal includes:
- at least one first annular sealing groove configured to extend substantially coaxially with the drive shaft and provided on a first axial wall surface of the one-piece sealing member or on the back-side of the first impeller, and at least one first annular sealing rib provided on the back-side of the first impeller or on said first axial wall surface of the one-piece sealing member, the at least one first annular sealing groove being configured to cooperate with the at least one first annular sealing rib, and/or
- at least one second annular sealing groove configured to extend substantially coaxially with the drive shaft and provided on a second axial wall surface of the one-piece sealing member or on the back-side of the second impeller, and at least one second annular sealing rib provided on the back-side of the second impeller or on said second axial wall surface of the one-piece sealing member, the at least one second annular sealing groove being configured to cooperate with the at least one second annular sealing rib.
According to an embodiment of the invention, the first impeller includes an axial bore configured to firmly receive an axial end portion of the drive shaft of the double-stage centrifugal turbo-compressor.
According to an embodiment of the invention, the axial bore extends along the entire axial length of the first impeller. According to another embodiment of the invention, the axial bore extends along a part of the axial length of the first impeller, and is thus a blind axial bore. According to an embodiment of the invention, one of the first and second impellers includes an axial mounting portion and the other of the first and second impellers includes an axial receiving hole emerging in the back-side of said other of the first and second impellers, the axial mounting portion extending at least partially within the axial receiving hole and being firmly mounted in the axial receiving hole.
According to an embodiment of the invention, the circumferential bottom surface of the radial annular groove is defined by the axial mounting portion.
According to an embodiment of the invention, the axial mounting portion partially defines the axial bore.
According to an embodiment of the invention, the first impeller includes the axial mounting portion and the second impeller includes the axial receiving hole, the axial mounting portion including a longitudinal hole having a first hole end emerging in the axial bore of the first impeller and a second hole end emerging in the axial receiving hole. According to an embodiment of the invention, the longitudinal hole is configured to extend coaxially with the drive shaft. The provision of the longitudinal hole ensures a secure attachment of the second impeller to the first impeller, and particularly a better shrink fit between the first and second impeller, while limiting deformation of functional surfaces (blade and sealing geometry) of the second impeller. Indeed, during assembly of the axial mounting portion within the axial receiving hole of the second impeller, the longitudinal hole allows deformation of the axial mounting portion of the first impeller towards its longitudinal axis and thus limits expansion of the outer diameter of the second impeller.
Further, such a longitudinal hole ensures a discharge of the air which is confined between the end portion of the drive shaft and the axial bore of first impeller during the mounting of the end portion of the drive shaft in said axial bore, and thus facilitates the attachment of the first impeller to the drive shaft.
According to an embodiment of the invention, the second impeller is firmly connected to the axial mounting portion of the first impeller, for example by press-fit or shrink-fit, and advantageously by heat shrink fit, i.e. by heat shrinking.
According to an embodiment of the invention, the axial receiving hole extends along the entire axial length of the second impeller.
According to an embodiment of the invention, an end portion of the axial mounting portion projects from a front end of the second impeller. Advantageously, the end portion of the axial mounting portion is rounded. According to an embodiment of the invention, the second impeller includes an axial tubular portion extending from the back-side of the second impeller and around the axial mounting portion provided on the first impeller.
According to an embodiment of the invention, the axial tubular portion partially defines the axial receiving hole.
According to an embodiment of the invention, the circumferential bottom surface of the radial annular groove is defined by the axial tubular portion.
According to an embodiment of the invention, the first impeller includes an axial annular groove emerging in the back-side of the first impeller, the axial tubular portion of the second impeller extending partially in the axial annular groove.
According to another embodiment of the invention, the first impeller includes the axial receiving hole and the second impeller includes the axial mounting portion.
According to an embodiment of the invention, the second impeller includes a tubular mounting portion configured to be firmly and directly connected to the drive shaft, for example by press-fit or shrink-fit.
According to an embodiment of the invention, the tubular mounting portion of the second impeller is configured to be firmly and directly connected to the end portion of the drive shaft.
According to an embodiment of the invention, the tubular mounting portion of the second impeller axially extends from the back-side of the second impeller.
According to an embodiment of the invention, the circumferential bottom surface of the radial annular groove is defined by the tubular mounting portion.
According to an embodiment of the invention, the first impeller at least partially defines an axial annular groove emerging in the back-side of the first impeller, the tubular mounting portion of the second impeller extending partially in said axial annular groove.
The present invention also relates to a double-stage centrifugal turbo- compressor including a drive shaft and a double-stage impeller arrangement according to any one of claims 1 to 6, the first and second impellers being connected to the drive shaft.
According to an embodiment of the invention, the double-stage centrifugal turbo-compressor further includes a thrust bearing arrangement configured to limit an axial movement of the drive shaft during operation. The double- stage centrifugal turbo-compressor may further include a radial bearing arrangement configured to rotatably support the drive shaft.
According to an embodiment of the invention, the double-stage centrifugal turbo-compressor further includes a driving device configured to drive in rotation the drive shaft about a rotation axis, the thrust bearing arrangement being located between the driving device and the first impeller. Advantageously, the radial bearing arrangement is also located between the driving device and the first impeller.
The present invention further relates to a method for assembling a double-stage centrifugal turbo-compressor including the following steps:
- connecting a first impeller to an axial end portion of a drive shaft of the double-stage centrifugal turbo-compressor,
- axially positioning a one-piece sealing member having an annular disc shape so as to face a back-side of the first impeller, and
- connecting a second impeller to the axial end portion of the drive shaft or to the first impeller so that a back-side of the second impeller faces the one-piece sealing member and so that the first and second impellers form a radial annular groove in which the one-piece sealing member is at least partially arranged.
The present invention also relates to a method for assembling a double- stage centrifugal turbo-compressor including the following steps:
- axially positioning a one-piece sealing member having an annular disc shape onto a first impeller so as to face a back-side of the first impeller,
- connecting, for example by shrink-fit and notably by heat shrink fit, a second impeller to the first impeller so that a back-side of the second impeller faces the one-piece sealing member and so that the first and second impellers form a radial annular groove in which the one-piece sealing member is at least partially arranged,
- connecting the first impeller to an axial end portion of a drive shaft of the double-stage centrifugal turbo-compressor.
These and other advantages will become apparent upon reading the following description in view of the drawings attached hereto representing, as non- limiting examples, embodiments of a double-stage centrifugal turbo-compressor according to the invention.
Brief description of the drawings The following detailed description of several embodiments of the invention is better understood when read in conjunction with the appended drawings being understood, however, that the invention is not limited to the specific embodiments disclosed.
Figure 1 is a longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a first embodiment of the invention.
Figure 2 is an enlarged longitudinal sectional view of the double-stage centrifugal turbo-compressor of figure 1.
Figure 3 is a partial exploded perspective view of the double-stage centrifugal turbo-compressor of figure 1.
Figure 4 is an enlarged longitudinal sectional view of details of the double-stage centrifugal turbo-compressor of figure 1.
Figure 5 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a second embodiment of the invention.
Figure 6 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a third embodiment of the invention.
Figure 7 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a fourth embodiment of the invention.
Figure 8 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a fifth embodiment of the invention.
Figure 9 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a sixth embodiment of the invention.
Figures 10 and 11 are partial longitudinal sectional views showing various steps for assembling the double-stage centrifugal turbo-compressor according to the sixth embodiment of the invention.
Figure 12 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a seventh embodiment of the invention.
Figure 13 is a partial longitudinal sectional view of a double-stage centrifugal turbo-compressor according to a eighth embodiment of the invention.
Detailed description of the invention
Figures 1 to 4 represent a double-stage centrifugal turbo-compressor 2 according to a first embodiment of the invention.
The double-stage centrifugal turbo-compressor 2 includes a casing 3, and a drive shaft 4 rotatably arranged within the casing 3 and extending along a longitudinal axis A. The drive shaft 4 includes a first axial end portion 5, a second axial end portion 6 opposite to the first axial end portion 5, and an intermediate portion 7 arranged between the first and second end axial portions 5, 6.
The double-stage centrifugal turbo-compressor 2 further includes a first compression stage 8 and a second compression stage 9 configured to compress a refrigerant. The first compression stage 8 includes a fluid inlet 11 and a fluid outlet 12, while the second compression stage 9 includes a fluid inlet 13 and a fluid outlet 14, the fluid outlet 12 of the first compression stage 8 being fluidly connected to the fluid inlet 13 of the second compression stage 9.
The first and second compression stages 8, 9 are partially defined by a double-stage impeller arrangement 17. The double-stage impeller arrangement 17 includes a first impeller 18 and a second impeller 19 which are connected to the first axial end portion 5 of the drive shaft 4 and which extend coaxially with the drive shaft 4. Particularly the first impeller 18 includes an axial bore 20 emerging in the front end of the first impeller 18 and configured to firmly receive the first axial end portion 5 of the drive shaft 4. According to the first embodiment of the invention, the axial bore 20 of the first impeller 18 extends along the entire axial length of the first impeller 18.
Each of the first and second impellers 18, 19 includes a front-side 21, 22 equipped with a plurality of blades 23, 24 configured to accelerate, during rotation of the drive shaft 4, the refrigerant entering the respective one of the first and second compression stages 8, 9, and to deliver the accelerated refrigerant to a diffuser arranged at the radial outside edge of the respective one of the first and second impellers 18, 19. Each of the first and second impellers 18, 19 also includes a back-side 25, 26 extending substantially perpendicularly to the drive shaft 4.
The first and second impellers 18, 19 are arranged in a back-to-back configuration, so that the directions of fluid flow at the flow inlet 11, 13 of the first and second compression stages 8, 9 are opposite to each other.
Advantageously, the second impeller 19 is distinct and separated from the first impeller 18 so as to enable notably an adjustment of the axial distance between the back-sides 25, 26 of the first and second impellers 18, 19 during assembly of the double-stage impeller arrangement 17. According to the first embodiment of the invention shown on figures 1 to 4, the second impeller 19 includes a tubular mounting portion 27 axially extending from the back-side 26 of the second impeller 19 and firmly and directly connected to the first end portion 5 of the drive shaft 4, for example by press-fit or shrink-fit. Further, according to the first embodiment of the invention, the first impeller 18 and the drive shaft 4 define an axial annular groove 28 emerging in the back-side 25 of the first impeller 18, and the tubular mounting portion 27 extends partially in the axial annular groove 28.
The double-stage impeller arrangement 17 also includes a radial annular groove 29 formed between the back-sides 25, 26 of the first and second impellers 18, 19. According to the first embodiment of the invention, the circumferential bottom surface 30 of the radial annular groove 29 is defined by the tubular mounting portion 27.
The double-stage impeller arrangement 17 further includes an interstage sealing device provided between the first and second impellers 18, 19. The inter- stage sealing device includes a one-piece sealing member 32 extending substantially perpendicularly to the drive shaft 4 and at least partially arranged within the radial annular groove 29. The one-piece sealing member 32 is stationary and has an annular disc shape. The one-piece sealing member 32 has an inner peripheral surface 33 and an outer peripheral surface 34.
According to the embodiment shown on the figures 1 to 4, the one-piece sealing member 32 comprises a central annular sealing portion 32.1 arranged within the radial annular groove 29 and an outer annular sealing portion 32.2 extending outside the radial annular groove 29. The outer annular sealing portion 32.2 may have a thickness higher than the thickness of the central annular sealing portion 32.1. The central annular sealing portion 32.1 has a first axial wall surface 35 and a second axial wall surface 36 opposite to the first axial wall surface 35. Advantageously, the first axial wall surface 35 and the back-side 25 of the first impeller 18 define a first axial gap and the second axial wall surface 36 and the back-side 26 of the second impeller 19 define a second axial gap.
The double-stage impeller arrangement 17 further includes a labyrinth seal 37 provided between the first and second compressor stages 8, 9 and in the radial annular groove 29. The labyrinth seal 37 is configured to minimize or control fluid flow across the labyrinth seal 37, and particularly from the second compression stage 9 to the first compression stage 8. The labyrinth seal 37 is advantageously formed by the inner peripheral surface 33 of the one-piece sealing member 32 and the circumferential bottom surface 30 of the radial annular groove 29.
The labyrinth seal 37 may be formed, for example, by a succession of annular stationary steps formed on the inner peripheral surface 33 of the one-piece sealing member 32, and by a succession of annular rotary steps formed on the circumferential bottom surface 30 of the radial annular groove 29. The labyrinth seal 37 may also be formed by a circumferential protrusion extending from the circumferential bottom surface 30 of the radial annular groove 29, and by an annular recess provided in the inner peripheral surface 33 of the one-piece sealing member 32 and receiving the circumferential protrusion.
The double-stage centrifugal turbo-compressor 2 further includes an electric motor 38 configured to drive in rotation the drive shaft 4 about the longitudinal axis A.
The double-stage centrifugal turbo-compressor 2 further includes a thrust bearing arrangement 39, also named axial bearing arrangement, configured to limit an axial movement of the drive shaft 4 during operation. The thrust bearing arrangement 39 may be a fluid thrust bearing arrangement, and for example a gas thrust bearing arrangement. The thrust bearing arrangement 39 may include an annular thrust bearing member 40 arranged on the outer surface of the intermediate portion 7 of the drive shaft 4, and located between the electric motor 38 and the first compression stage 8. The thrust bearing member 40 may be integrally formed with the drive shaft 4, or may be secured to the latter.
The double-stage centrifugal turbo-compressor 2 may also include a radial bearing arrangement configured to rotatably support the drive shaft 4. The radial bearing arrangement may include a radial bearing surrounding the drive shaft 4 and configured to cooperate with the outer surface of the drive shaft 4. The radial bearing may be a fluid radial bearing, and for example a gas radial bearing. According to an embodiment of the invention, the radial bearing may extend along a part of the intermediate portion 7 of the drive shaft 4. According to another embodiment of the invention, the radial bearing arrangement may include a plurality of radial bearings distributed along the axial length of the drive shaft 4.
Figure 5 represents a double-stage centrifugal turbo-compressor 2 according to a second embodiment of the invention which differs from the first embodiment shown on figures 1 to 4 notably in that the second impeller 19 includes an axial receiving hole 41, which may be blind, emerging in the back-side 26 of the second impeller 19 and in that the first impeller 18 includes an axial mounting portion 42 extending at least partially within the axial receiving hole 41 and being firmly mounted in the axial receiving hole 41. According to said second embodiment, the second impeller 19 is firmly connected to the axial mounting portion 42 of the first impeller 18, for example by press-fit or shrink-fit.
Advantageously, according to the second embodiment of the invention, the axial mounting portion 42 includes a longitudinal hole 43 having a first hole end 43.1 emerging in the axial bore 20 of the first impeller 18 and a second hole end 43.2 emerging in the axial receiving hole 41. Advantageously, the longitudinal hole 43 extends coaxially with the drive shaft 4.
Further, according to the second embodiment of the invention, the circumferential bottom surface 30 of the radial annular groove 29 is defined by the axial mounting portion 42, and the axial bore 20 of the first impeller 18 is blind and thus extends along only a part of the axial length of the first impeller 18. Moreover, the axial mounting portion 42 may partially define the axial bore 20.
Figure 6 represents a double-stage centrifugal turbo-compressor 2 according to a third embodiment of the invention which differs from the second embodiment shown on figure 5 notably in that the axial receiving hole 41 extends along the entire axial length of the second impeller 19 and in that an end portion of the axial mounting portion 42 projects from a front end 42.1 of the second impeller 19.
Figure 7 represents a double-stage centrifugal turbo-compressor 2 according to a fourth embodiment of the invention which differs from the second embodiment shown on figure 5 notably in that the second impeller 19 includes an axial tubular portion 44 extending from the back-side 26 of the second impeller 19 and around the axial mounting portion 42 of the first impeller 18. According to the fourth embodiment of the invention, the axial tubular portion 44 partially defines the axial receiving hole 41, and the circumferential bottom surface 30 of the radial annular groove 29 is defined by the axial tubular portion 44.
Figure 8 represents a double-stage centrifugal turbo-compressor 2 according to a fifth embodiment of the invention which differs from the fourth embodiment shown on figure 7 in that the first impeller 18 includes an axial annular groove 45 emerging in the back-side 25 of the first impeller 18 and in that the axial tubular portion 44 of the second impeller 19 extends partially in the axial annular groove 45.
Figures 9 to 11 represent a double-stage centrifugal turbo-compressor 2 according to a sixth embodiment of the invention which differs from the second embodiment shown on figure 5 notably in that the second impeller 19 includes the axial mounting portion 42 and that the first impeller 18 includes the axial receiving hole 41. According to said embodiment, the axial receiving hole 41 is formed by the axial bore 20.
According to such a configuration of the first and second impellers, instead of successively connecting the first impeller 18 to the first end portion 5 of the drive shaft 4, positioning the one-piece sealing member 32 so as to face the back-side 25 of the first impeller 18 and connecting the second impeller 19 to the first end portion 5 of the drive shaft 4 or to the first impeller 18, it is possible to:
- pre-assembly the first and second impellers 18, 19, for example by heat shrink-fit (the first impeller 18 being heated up and the second impeller 19, at ambient temperature, being inserted into the axial receiving hole 41 of the first impeller 18), with the one-piece sealing member 32 in place between the first and second impellers 18, 19;
- assembly, for example by shrink-fit, the first and second impellers 18, 19 and the one-piece sealing member 32 on the first end portion of the drive shaft 4.
For example, the method for assembling the double-stage centrifugal turbo-compressor 2 according to the sixth embodiment of the invention includes the following steps:
- axially positioning the one-piece sealing member 32 onto the first impeller 18 so as to face the back-side 25 of the first impeller 18 (see figure 10),
- connecting the second impeller 19, for example by shrink-fit and notably by heat shrink fit, to the first impeller 18 so that the back-side 26 of the second impeller 19 faces the one-piece sealing member 32 and so that the first and second impellers 18, 19 form the radial annular groove 29 in which the one-piece sealing member 32 is at least partially arranged (see figure 11), and
- connecting the first impeller 18 to the axial end portion 5 of the drive shaft 4 of the double-stage centrifugal turbo-compressor 2 (see figure 9).
Particularly, such a pre-assembly step avoids using cold shrink fit process, which is a difficult and expensive assembly process, to insert the second impeller 19 into the first impeller 18.
Figure 12 represents a double-stage centrifugal turbo-compressor 2 according to a seventh embodiment of the invention which differs from the first embodiment notably in that the labyrinth seal 37 is formed by a plurality of concentric annular sealing grooves 46, 47 respectively formed on the first and second axial wall surfaces 35, 36 of the one-piece sealing member 32, and by a succession of concentric annular sealing ribs 48, 49 respectively formed on the back-sides 25, 26 of the first and second impellers 18, 19.
Figure 13 represents a double-stage centrifugal turbo-compressor 2 according to a eighth embodiment of the invention which differs from the first embodiment notably in that the labyrinth seal 37 is formed by two concentric annular sealing grooves 51, 52 respectively formed on the back-sides 25, 26 of the first and second impellers 18, 19, and by two concentric annular sealing ribs 53, 54 respectively formed on the first and second axial wall surfaces 35, 36 of the one-piece sealing member 32.
Of course, the invention is not restricted to the embodiments described above by way of non-limiting examples, but on the contrary it encompasses all embodiments thereof.

Claims

1. A double-stage impeller arrangement (17) for a double-stage centrifugal turbo-compressor (2), the double-stage impeller arrangement (17) including:
- a first impeller (18) and a second impeller (19), each of the first and second impellers (18, 19) having a front-side (21, 22) and a back-side (25, 26), the first and second impellers (18, 19) being configured to be connected to a drive shaft (4) of the double-stage centrifugal turbo-compressor (2) and being arranged in a back-to- back configuration,
- a radial annular groove (29) formed between the back-sides (25, 26) of the first and second impellers (18, 19), and
- an inter-stage sealing device provided between the first and second impellers (18, 19),
characterized in that the second impeller (19) is distinct and separated from the first impeller (18) so as to enable an adjustment of an axial distance between the back-sides (25, 26) of the first and second impellers (18, 19), and in that the interstage sealing device includes a one-piece sealing member (32) having an annular disc shape and being at least partially arranged within the radial annular groove (29).
2. The double-stage impeller arrangement (17) according to claim 1, further including a labyrinth seal (37) configured to minimize or control fluid flow across the labyrinth seal (37), the labyrinth seal (37) being at least partially formed by an inner peripheral surface (33) of the one-piece sealing member (32) and a circumferential bottom surface (30) of the radial annular groove (29).
3. The double-stage impeller arrangement (17) according to claim 2, wherein the labyrinth seal (37) includes at least one annular sealing groove (46, 47, 51, 52) configured to extend substantially coaxially with the drive shaft (4) and provided on an axial wall surface of the one-piece sealing member (32) or on the backside of one of the first and second impellers (18, 19), and at least one annular sealing rib (48, 49, 53, 54) provided on the back-side of one of the first and second impellers (18, 19) or on said axial wall surface of the one-piece sealing member (32), the at least one annular sealing groove (46, 47, 51, 52) being configured to cooperate with the at least one annular sealing rib (48, 49, 53, 54).
4. The double-stage impeller arrangement (17) according to any one of claims 1 to 3, wherein the first impeller (18) includes an axial bore (20) configured to firmly receive an axial end portion (5) of the drive shaft (4) of the double-stage centrifugal turbo-compressor (2).
5. The double-stage impeller arrangement (17) according to any one of claims 1 to 4, wherein one of the first and second impellers (18, 19) includes an axial mounting portion (42) and the other of the first and second impellers (18, 19) includes an axial receiving hole (41) emerging in the back-side of said other of the first and second impellers (18, 19), the axial mounting portion (42) extending at least partially within the axial receiving hole (41) and being firmly mounted in the axial receiving hole (41).
6. The double-stage impeller arrangement (17) according to claim 5, wherein the first impeller (18) includes the axial mounting portion (42) and the second impeller (19) includes the axial receiving hole (41), the axial mounting portion (42) including a longitudinal hole (43) having a first hole end (43.1) emerging in the axial bore (20) of the first impeller (18) and a second hole end (43.2) emerging in the axial receiving hole (41).
7. The double-stage impeller arrangement (17) according to any one of claims 1 to 4, wherein the second impeller (19) includes a tubular mounting portion (27) configured to be firmly and directly connected to the drive shaft (4).
8. A double-stage centrifugal turbo-compressor (2) including a drive shaft
(4) and a double-stage impeller arrangement (17) according to any one of claims 1 to 7, the first and second impellers (18, 19) being connected to the drive shaft (4).
9. The double-stage centrifugal turbo-compressor (2) according to claim 8, further including a thrust bearing arrangement configured to limit an axial movement of the drive shaft (4) during operation.
10. The double-stage centrifugal turbo-compressor (2) according to claim 9, further including a driving device configured to drive in rotation the drive shaft (4) about a rotation axis, the thrust bearing arrangement being located between the driving device and the first impeller (18).
11. Method for assembling a double-stage centrifugal turbo-compressor (2) including the following steps:
- connecting a first impeller (18) to an axial end portion (5) of a drive shaft (4) of the double-stage centrifugal turbo-compressor (2),
- axially positioning a one-piece sealing member (32) having an annular disc shape so as to face a back-side (25) of the first impeller (18), and
- connecting a second impeller (19) to the axial end portion (5) of the drive shaft (4) or to the first impeller so that a back-side (26) of the second impeller (19) faces the one-piece sealing member (32) and so that the first and second impellers (18, 19) form a radial annular groove (29) in which the one-piece sealing member (32) is at least partially arranged.
12. Method for assembling a double-stage centrifugal turbo-compressor (2) including the following steps:
- axially positioning a one-piece sealing member (32) having an annular disc shape onto a first impeller (18) so as to face a back-side (25) of the first impeller (18),
- connecting a second impeller (19) to the first impeller (18) so that a back-side (26) of the second impeller (19) faces the one-piece sealing member (32) and so that the first and second impellers (18, 19) form a radial annular groove (29) in which the one-piece sealing member (32) is at least partially arranged,
- connecting the first impeller (18) to an axial end portion (5) of a drive shaft (4) of the double-stage centrifugal turbo-compressor (2).
PCT/EP2018/055807 2017-03-08 2018-03-08 A double-stage impeller arrangement for a double-stage centrifugal turbo-compressor WO2018162660A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1751909 2017-03-08
FR1751909A FR3063777A1 (en) 2017-03-08 2017-03-08 DUAL-STAGE WHEEL ARRANGEMENT FOR A DOUBLE-STAGE CENTRIFUGAL TURBOCHARGER

Publications (1)

Publication Number Publication Date
WO2018162660A1 true WO2018162660A1 (en) 2018-09-13

Family

ID=59070798

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2018/055807 WO2018162660A1 (en) 2017-03-08 2018-03-08 A double-stage impeller arrangement for a double-stage centrifugal turbo-compressor

Country Status (2)

Country Link
FR (1) FR3063777A1 (en)
WO (1) WO2018162660A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109611346A (en) * 2018-11-30 2019-04-12 中国航发湖南动力机械研究所 Centrifugal compressor and its design method
CN113586457A (en) * 2021-09-10 2021-11-02 宜兴市宙斯泵业有限公司 Centrifugal slurry pump for conveying slurry containing solid
KR20220159795A (en) 2021-05-26 2022-12-05 엘지전자 주식회사 Turbo Compressor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050005606A1 (en) * 2003-07-11 2005-01-13 Gary Vrbas Turbocharger compressor with non-axisymmetric deswirl vanes
US20070122296A1 (en) * 2005-11-30 2007-05-31 Honeywell International, Inc. Turbocharger having two-stage compressor with boreless first-stage impeller
EP3043073A1 (en) * 2015-01-08 2016-07-13 Honeywell International Inc. Multistage radial compressor baffle
FR3038665A1 (en) * 2015-07-07 2017-01-13 Danfoss Commercial Compressors

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050005606A1 (en) * 2003-07-11 2005-01-13 Gary Vrbas Turbocharger compressor with non-axisymmetric deswirl vanes
US20070122296A1 (en) * 2005-11-30 2007-05-31 Honeywell International, Inc. Turbocharger having two-stage compressor with boreless first-stage impeller
EP3043073A1 (en) * 2015-01-08 2016-07-13 Honeywell International Inc. Multistage radial compressor baffle
FR3038665A1 (en) * 2015-07-07 2017-01-13 Danfoss Commercial Compressors

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109611346A (en) * 2018-11-30 2019-04-12 中国航发湖南动力机械研究所 Centrifugal compressor and its design method
KR20220159795A (en) 2021-05-26 2022-12-05 엘지전자 주식회사 Turbo Compressor
CN113586457A (en) * 2021-09-10 2021-11-02 宜兴市宙斯泵业有限公司 Centrifugal slurry pump for conveying slurry containing solid

Also Published As

Publication number Publication date
FR3063777A1 (en) 2018-09-14

Similar Documents

Publication Publication Date Title
US10794390B2 (en) Modular turbo compressor shaft
EP3592982B1 (en) A bearing arrangement for a drive shaft of a turbo-machine, and a turbo-machine including such a bearing arrangement
EP3401549B1 (en) Turbo compressor
US8616831B2 (en) Simplified housing for a fuel cell compressor
WO2018162660A1 (en) A double-stage impeller arrangement for a double-stage centrifugal turbo-compressor
US9664055B2 (en) Impeller and rotary machine provided with the same
WO2016193002A1 (en) A centrifugal refrigeration compressor
US10619645B2 (en) Centrifugal compressor having an inter-stage sealing arrangement
EP3421816B1 (en) Centrifugal compressor
US6461123B1 (en) Turbomolecular pump
US7278822B2 (en) Turbomolecular pump
EP3613993B1 (en) A turbo compressor provided with an axial bearing cooling arrangement
US6561755B1 (en) Turbomolecular pump
CN101832272B (en) Multi-stage centrifugal pump assembly
JP3894115B2 (en) Turbo compressor
CN210660710U (en) Support assembly and ventilator
EP3592983B1 (en) A centrifugal turbo-compressor
WO2020039006A1 (en) A turbo compressor having a flexible contact area between a bearing sleeve and a fixed compressor part
EP3613992B1 (en) A turbo compressor having a bearing sleeve provided with axial end cuts
EP3557082B1 (en) Centrifugal compressor
US20130064659A1 (en) Centrifugal compressor
US20240102487A1 (en) Pump Assembly
JP2023077695A (en) Multistage compressor
CN117581024A (en) Turbine type fluid machine and refrigeration device
CN114635872A (en) Fan and cleaning equipment

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18708705

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18708705

Country of ref document: EP

Kind code of ref document: A1