WO2020039006A1 - A turbo compressor having a flexible contact area between a bearing sleeve and a fixed compressor part - Google Patents

A turbo compressor having a flexible contact area between a bearing sleeve and a fixed compressor part Download PDF

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Publication number
WO2020039006A1
WO2020039006A1 PCT/EP2019/072400 EP2019072400W WO2020039006A1 WO 2020039006 A1 WO2020039006 A1 WO 2020039006A1 EP 2019072400 W EP2019072400 W EP 2019072400W WO 2020039006 A1 WO2020039006 A1 WO 2020039006A1
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WO
WIPO (PCT)
Prior art keywords
bearing
bearing sleeve
axial
flexible contact
drive shaft
Prior art date
Application number
PCT/EP2019/072400
Other languages
French (fr)
Inventor
Patrice Bonnefoi
Yves Rosson
Stan VANDESTEENE
Julien COTE
Original Assignee
Danfoss A/S
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 Danfoss A/S filed Critical Danfoss A/S
Publication of WO2020039006A1 publication Critical patent/WO2020039006A1/en

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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
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/668—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps damping or preventing mechanical vibrations
    • 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
    • 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
    • F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
    • F04D29/056—Bearings
    • F04D29/057—Bearings hydrostatic; hydrodynamic
    • 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

  • a turbo compressor having a flexible contact area between a bearing sleeve and a fixed compressor part
  • the present invention relates to a turbo compressor, and particularly to a refrigeration turbo compressor.
  • a refrigeration turbo compressor may include:
  • a drive shaft including a first axial end portion and a second axial end portion opposite to the first axial end portion
  • At least one compression stage configured to compress a refrigerant, the at least one compression stage including at least one impeller connected to the first axial end portion of the drive shaft,
  • an electrical motor configured to drive in rotation the drive shaft about a rotation axis, the electrical motor including a stator and a rotor, the rotor being connected to the second axial end portion of the drive shaft,
  • bearing sleeve having a longitudinal axis and being located between the electrical motor and the at least one impeller, the bearing sleeve surrounding the drive shaft and being configured to rotatably support the drive shaft, the bearing sleeve including an axial end face which faces towards the at least one impeller and a contact surface which is located at the axial end face of the bearing sleeve and which is oriented perpendicularly with respect to the longitudinal axis of the bearing sleeve, the contact surface being configured to cooperate with the thrust bearing arrangement, and
  • a fixed compressor part configured to center the bearing sleeve on a predetermined axis, the fixed compressor part including a radial inner surface configured to cooperate with an outer circumferential surface of the bearing sleeve.
  • the thrust bearing arrangement particularly includes:
  • a thrust bearing member arranged on the outer surface of the drive shaft, the thrust bearing member extending radially outwardly with respect to the drive shaft, - a first axial bearing plate having an annular ring shape, the first axial bearing plate having a first surface and a second surface opposite to the first surface of the first axial bearing plate,
  • a second axial bearing plate having an annular ring shape, the second axial bearing plate having a first surface axially facing the first axial bearing plate and a second surface opposite to the first surface of the second axial bearing plate, and
  • the contact surface of the bearing sleeve abuts the second surface of the second axial bearing plate and the thrust bearing arrangement cooperates with the first surfaces of the first and second axial bearing plates in order to limit an axial movement of the drive shaft.
  • the centering of the bearing sleeve by the fixed compressor part induces radial deformations of the bearing sleeve during assembly of the turbo compressor, and thus induces deformations of the axial end face of the bearing sleeve. Further the axial end face of the bearing sleeve is also deformed due to thermal expansion gradients oriented in a radial direction occurring during operation of the turbo compressor.
  • Such a deformation of the axial end face of the bearing sleeve may induce deformations of the first and second axial bearing plates, and thus of the gas films in the thrust bearing arrangement when the latter is a gas thrust bearing arrangement.
  • the centering of the bearing sleeve by the fixed compressor part may deteriorate the parallel positioning of the first and second axial bearing plates, and may thus lead to seizure of the thrust bearing arrangement and shortened lifetime of the turbo compressor.
  • deformations of the axial end face of the bearing sleeve does not necessarily lead to a seizure but can also lead to an instability of the thrust bearing arrangement, which causes the generation of vibrations of the drive shaft and thus contacts of the latter with static parts of the turbo compressor leading to scratches or breaking of the drive shaft.
  • Another object of the present invention is to provide a turbo compressor which is reliable, and which is particularly not subjected to the above-mentioned deformations.
  • such a turbo compressor including:
  • a drive shaft including a first axial end portion and a second axial end portion opposite to the first axial end portion
  • At least one compression stage configured to compress a refrigerant, the at least one compression stage including at least one impeller connected to the first axial end portion of the drive shaft,
  • an electrical motor configured to drive in rotation the drive shaft about a rotation axis, the electrical motor including a stator and a rotor, the rotor being connected to the second axial end portion of the drive shaft,
  • bearing sleeve having a longitudinal axis and being located between the electrical motor and the at least one impeller, the bearing sleeve surrounding the drive shaft and being configured to rotatably support the drive shaft, the bearing sleeve including an axial end face which faces towards the at least one impeller and a contact surface which is located at the axial end face of the bearing sleeve and which is configured to cooperate with the thrust bearing arrangement, and
  • a fixed compressor part configured to center the bearing sleeve on a predetermined axis
  • the fixed compressor part including a radial inner surface configured to cooperate with an outer circumferential surface of the bearing sleeve, wherein a flexible contact area is formed at an interface between the outer circumferential surface of the bearing sleeve and the radial inner surface of the fixed compressor part.
  • Such a configuration of the turbo compressor allows a radial deformation of the flexible contact area between the fixed compressor part and the bearing sleeve, and thus avoids or at least strongly reduces radial deformations of the bearing sleeve and therefore deformations of the axial end face of the bearing sleeve.
  • the configuration of the turbo compressor according to the present invention avoids a seizure or an unstability of the thrust bearing arrangement, and therefore improves the reliability of the turbo compressor and increases the lifetime of the turbo compressor.
  • the turbo compressor may also include one or more of the following features, taken alone or in combination.
  • the flexible contact area is flexible at least in a radial direction.
  • the flexible contact area is configured to avoid deformation of the axial end face of the bearing sleeve due to mechanical loads from initial assembling of the turbo compressor and/or due to thermal expansion gradients oriented in a radial direction during operation of the turbo compressor.
  • the flexible contact area is provided on the bearing sleeve and/or the fixed compressor part.
  • the flexible contact area is provided on the bearing sleeve and is separated from the axial end face of the bearing sleeve.
  • the flexible contact area is formed by a flexible contact part provided on the bearing sleeve or on the fixed compressor part, the flexible contact part being substantially tubular and being substantially coaxial with the longitudinal axis of the bearing sleeve.
  • the flexible contact part is provided on the fixed compressor part and the radial inner surface of the fixed compressor part is provided on the flexible contact part. Therefore during assembly of the turbo compressor, the flexible contact part being greatly less stiff than the bearing sleeve, it will deform and thus strongly reduces the deformation of the bearing sleeve for an equivalent interference between the fixed compressor part and the bearing sleeve.
  • the flexible contact part is configured to center the bearing sleeve on the predetermined axis.
  • the flexible contact part protrudes from an axial surface of the fixed compressor part which faces towards the bearing sleeve.
  • the flexible contact part tapers radially towards the electric motor.
  • the flexible contact part is provided on the bearing sleeve and the outer circumferential surface of the bearing sleeve is at least partially provided on the flexible contact part.
  • Such a configuration of the flexible contact part allows to separate the flexible contact area from the contact surface of the bearing sleeve. Therefore, during assembly of the turbo compressor, the flexible contact part will deform, but without impacting the contact surface of the bearing sleeve and thus the thrust bearing arrangement.
  • the bearing sleeve includes an annular groove formed in the axial end face of the bearing sleeve and extending around the longitudinal axis of the bearing sleeve, the flexible contact part being internally delimited by the annular groove.
  • the flexible contact area is formed by several flexible contact members angularly distributed around the longitudinal axis of the bearing sleeve and provided on the bearing sleeve or on the fixed compressor part.
  • the flexible contact members are regularly distributed around the longitudinal axis of the bearing sleeve.
  • each flexible contact member extends substantially parallely to the longitudinal axis of the bearing sleeve.
  • each flexible contact member is a flexible contact finger.
  • the axial end face of the bearing sleeve is planar and oriented perpendicularly with respect to the longitudinal axis of the bearing sleeve.
  • the bearing sleeve includes:
  • a radial bearing part which is tubular and which is configured to rotatably support the drive shaft
  • the flexible contact part is provided on the sleeve part.
  • the flexible contact members are provided on the sleeve part.
  • the annular groove is provided on the sleeve part.
  • the radial bearing part is a radial gas bearing part.
  • the radial bearing part has an inner diameter which is larger than an outer diameter of a bearing portion of the drive shaft which is surrounded by the radial bearing part, the bearing portion and the radial bearing part defining an annular gaseous chamber when the drive shaft is rotating.
  • the radial bearing part and the sleeve part are concentrically arranged.
  • the sleeve part is connected to the radial bearing part through a connecting part which is positioned away from the axial end face of the bearing sleeve.
  • the sleeve part and the radial bearing part are made in one piece.
  • the sleeve part is shorter than the radial bearing part along the longitudinal axis of the bearing sleeve.
  • the thrust bearing arrangement is a gas thrust bearing arrangement.
  • the thrust bearing arrangement is located between the at least one compression stage and the bearing sleeve.
  • the thrust bearing arrangement includes a thrust bearing member arranged on the outer surface of the drive shaft, the thrust bearing member extending substantially radially outwardly with respect to the drive shaft.
  • the thrust bearing arrangement includes:
  • first axial bearing plate having an annular ring shape, the first axial bearing plate having a first surface and a second surface opposite to the first surface of the first axial bearing plate,
  • a second axial bearing plate having an annular ring shape
  • the second axial bearing plate having a first surface axially facing the first axial bearing plate and a second surface opposite to the first surface of the second axial bearing plate, the second surface of the second axial bearing plate abutting against the contact surface of the bearing sleeve, and - a spacer ring being clamped between the first surfaces of the first and second axial bearing plates at radial outer portions of the first and second axial bearing plates, the spacer ring defining an axial distance between the first and second axial bearing plates.
  • the first and second axial bearing plates are parallel to each other.
  • the thrust bearing member extends into a space between radial inner portions of the first surfaces of the first and second axial bearing plates.
  • the bearing sleeve includes a cooling area formed in the outer circumferential surface of the bearing sleeve, and particularly of the sleeve part, and intended for the passage of a refrigerant so as to dissipate heat from the bearing sleeve.
  • the cooling area includes at least one annular cooling channel formed in the outer circumferential surface of the bearing sleeve and extending around the longitudinal axis of the bearing sleeve.
  • the turbo compressor includes an elastic element configured to axially bias the thrust bearing arrangement, and particularly the first and second axial bearing plates and the spacer ring, with a predetermined force against the contact surface of the bearing sleeve.
  • the elastic element is arranged between the second surface of the first axial bearing plate and the fixed compressor part.
  • the elastic element is an annular spring washer, preferably of the Belleville type.
  • the at least one compression stage includes a first and a second compression stage configured to compress a refrigerant, the first and second compression stages respectively including a first and a second impeller, the first and second impellers being connected to the first axial end portion of the drive shaft.
  • each of the first and second impellers has a front-side and a back-side, the first and second impellers being arranged in a back-to-back configuration.
  • the turbo compressor includes an hermetic casing, the drive shaft being rotatably arranged within the hermetic casing.
  • the second axial end portion of the drive shaft includes a rotor attachment part including an axial bore receiving the rotor.
  • the fixed compressor part includes an abutment surface against which abuts the bearing sleeve, and for example the contact surface of the bearing sleeve.
  • the bearing sleeve is immobilized axially with respect to the fixed compressor part.
  • the turbo compressor further includes a securing member axially tightening the bearing sleeve against the fixed compressor part, and for example against the abutment surface of the fixed compressor part.
  • the bearing sleeve is a one-piece bearing sleeve.
  • Figure 1 is a longitudinal section view of a turbo compressor according to a first embodiment of the invention.
  • Figure 2 is an enlarged view of a detail of figure 1.
  • Figure 3 is a longitudinal section view of a fixed compressor part of the turbo compressor of figure 1.
  • Figure 4 is a perspective view of the fixed compressor part of figure 3.
  • Figure 5 is a longitudinal section view of a fixed compressor part of a turbo compressor according to a second embodiment of the invention.
  • Figure 6 is a perspective view of the fixed compressor part of figure 5.
  • Figure 7 is a longitudinal section view of a fixed compressor part of a turbo compressor according to a third embodiment of the invention.
  • Figure 8 is a longitudinal section view of a turbo compressor according to a fourth embodiment of the invention.
  • Figure 9 is a longitudinal section view of a bearing sleeve of the turbo compressor of figure 8.
  • Figure 10 is a perspective view of the bearing sleeve of figure 9.
  • Figures 1 to 4 represent a refrigeration turbo compressor 1 according to a first embodiment of the invention, which may be for example a two-stage refrigeration turbo compressor.
  • the turbo compressor 1 includes an hermetic casing 2 and a drive shaft 3 which is rotatably arranged within the hermetic casing 2 and which extends along a longitudinal axis A.
  • the drive shaft 3 includes a first axial end portion 4, a second axial end portion 5 opposite to the first axial end portion 4, and an intermediate portion 6 located between the first and second axial end portions 4, 5.
  • the turbo compressor 1 further includes at least one impeller 7 connected to the first axial end portion 4 of the drive shaft 3, and configured to compress a refrigerant.
  • the turbo compressor 1 may for example include two impellers 7 arranged in a back-to-back configuration.
  • the turbo compressor 1 also includes an electrical motor 8 configured to drive in rotation the drive shaft 3 about the longitudinal axis A.
  • the electrical motor 8 includes a stator 9 and a rotor 10.
  • the rotor 10 is connected to the second axial end portion 5 of the drive shaft 3.
  • the second axial end portion 5 may include an axial bore 11 within which is arranged the rotor 10.
  • the rotor 10 may for example be firmly fitted, such as press-fitted or shrink fitted, within the axial bore 11.
  • the turbo compressor 1 further includes a thrust bearing arrangement, also named axial bearing arrangement, arranged between the at least one impeller 7 and the electrical motor 8 and configured to limit an axial movement of the drive shaft 3 during operation.
  • the thrust bearing arrangement is advantageously a gas thrust bearing arrangement.
  • the thrust bearing arrangement includes a thrust bearing member 12 arranged on an outer surface of the intermediate portion 6 of the drive shaft 3 and extending radially outwardly with respect to the drive shaft 3.
  • the thrust bearing member 12 has a flat disc shape, and includes a first axial end face 12.1 and a second axial end face 12.2 opposite to the first axial end face 12.1.
  • the thrust bearing arrangement also includes a first axial bearing plate 13 and a second axial bearing plate 14 each having an annular ring shape, and being arranged in parallel.
  • the first axial bearing plate 13 has a first surface 13.1 axially facing the second axial bearing plate 14 and a second surface 13.2 opposite to the first surface 13.1, while the second axial bearing plate 14 has a first surface 14.1 axially facing the first axial bearing plate 13 and a second surface 14.2 opposite to the first surface 14.1.
  • the thrust bearing arrangement further includes a spacer ring 15 surrounding the thrust bearing member 12, and being clamped between the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 at radial outer portions of the first and second axial bearing plates 13, 14.
  • the spacer ring 15 defines an axial distance between the first and second axial bearing plates 13, 14, said axial distance being slightly greater than the width of the thrust bearing member 12.
  • the radial inner portions of the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 define a space in which extends the thrust bearing member 12.
  • the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 are respectively configured to cooperate with the first and second axial end faces 12.1, 12.2 of the thrust bearing member 12.
  • the turbo compressor 1 is configured so that gas refrigerant is introduced between the thrust bearing member 12 and the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 to form a gas thrust bearing for the drive shaft 3.
  • the turbo compressor 1 also includes a bearing sleeve 16, also named bearing housing, which extends along the intermediate portion 6 of the drive shaft 3 and which is located between the thrust bearing arrangement and the electrical motor 8.
  • the bearing sleeve 16 may be a one-piece bearing sleeve, or may be made from separated parts assembled together.
  • the bearing sleeve 16 particularly includes:
  • radial bearing part 18 which is tubular and which surrounds the intermediate portion 6 of the drive shaft 3, the radial bearing part 18 being configured to rotatably support the drive shaft 3,
  • a sleeve part 19 surrounding the radial bearing part 18 and including an axial end face 20 which is planar and which extends perpendicularly to a longitudinal axis B of the bearing sleeve 16, the axial end face 20 facing towards the thrust bearing arrangement, and
  • the radial bearing part 18 and the sleeve part 19 are concentrically arranged, and the sleeve part 19 is connected to the radial bearing part 18 through a connecting part P which is away from the axial end face 20, and which is for example positioned substantially at a center of the axial length of the radial bearing part 18.
  • the sleeve part 19 may be shorter than the radial bearing part 18 along the longitudinal axis B of the bearing sleeve 16.
  • the radial bearing part 18 includes first and second radial bearing surfaces 18.1, 18.2 located on each side of the connecting part P and configured to cooperate with the drive shaft 3.
  • Each of the first and second radial bearing surfaces 18.1, 18.2 has advantageously an inner diameter which is larger than an outer diameter of a bearing portion 22 provided on the intermediate portion 6 of the drive shaft 3 and which is surrounded by the radial bearing part 18, such that the bearing portion 22 and each of the first and second radial bearing surfaces 18.1, 18.2 define an annular gaseous chamber when the drive shaft 3 is rotating.
  • the turbo compressor 1 is particularly configured so that gas refrigerant is introduced between the bearing portion 22 of the drive shaft 3 and the inner surface of the radial bearing part 18 to form a radial gas bearing for the drive shaft 3.
  • the bearing sleeve 16 further includes a contact surface 23 located at the axial end face 20 of sleeve part 19, and the second surface 14.2 of the second axial bearing plate 14 abuts against the contact surface 23.
  • the bearing sleeve 16 is axially immobilized with respect to a fixed compressor part 25 of the turbo compressor 1.
  • the turbo compressor 1 may therefore include a securing member 26 axially tightening the bearing sleeve 16 against the fixed compressor part 25, and more particularly against an abutment surface 27 provided on an axial surface of the fixed compressor part 25.
  • the securing member 26 may be secured, for example by screwing, to the hermetic casing 2 or to the fixed compressor part 25.
  • the contact surface 23 of the bearing sleeve 16 abuts against the abutment surface 27.
  • the fixed compressor part 25 is particularly configured to center the bearing sleeve 16 on a predetermined axis which is coaxial with the rotation axis of the drive shaft 3.
  • the fixed compressor part 25 also includes a radial inner surface 28 configured to cooperate with an outer circumferential surface 29 of the bearing sleeve 16, and particularly of the sleeve part 19.
  • the fixed compressor part 25 may for example include a tubular part 30 defining an inner housing in which are received the first and second axial bearing plates 13, 14 and the spacer ring 15.
  • the turbo compressor 1 further includes an elastic element 31 arranged between the second surface 13.2 of the first axial bearing plate 13 and the fixed compressor part 25.
  • the elastic element 31 axially biases the first and second axial bearing plates 13, 14 and the spacer ring 15 with a predetermined force, for example in the range of 1000 to 2000 N, against the contact surface 23 of the bearing sleeve 16.
  • the elastic element 31 is an annular spring washer, preferably of the Belleville type, coaxially arranged with the bearing sleeve 16 and the drive shaft 3.
  • the elastic element 31 is advantageously arranged in an annular recess formed in an axial surface of the fixed compressor part 25, and is in contact with a radial outer portion of the second surface 13.2 of the first axial bearing plate 13.
  • the elastic element 31 allows, notably when a thermal expansion occurs in the turbo compressor 1, an axial sliding of the first and second axial bearing plates 13, 14 and of the spacer ring 15 with respect to the fixed compressor part 25, and thus avoids deformations of said parts which could lead to a shortened lifetime of the turbo compressor 1.
  • the bearing sleeve 16 further includes a cooling area 36 formed in the outer circumferential surface 29 of the sleeve part 19.
  • the cooling area 36 may for example include an annular cooling channel 37 formed in the outer circumferential surface 29 of the sleeve part 19 and extending around the longitudinal axis B of the bearing sleeve 16, the annular cooling channel 37 being intended for the passage of a refrigerant so as to dissipate heat from the bearing sleeve 16.
  • the turbo compressor 1 includes a flexible contact area 32 which is formed at an interface between the outer circumferential surface 29 of the bearing sleeve 16 and the radial inner surface 28 of the fixed compressor part 25, and which is flexible at least in a radial direction.
  • the flexible contact area 32 is particularly configured to avoid deformation of the axial end face 20 of the bearing sleeve 16 due to mechanical loads from initial assembling of the turbo compressor 1 and/or due to thermal expansion gradients oriented in a radial direction during operation of the turbo compressor 1.
  • the flexible contact area 32 is formed by a flexible contact part 33 which is provided on the fixed compressor part 25 and which is substantially tubular, and the radial inner surface 28 is provided on the flexible contact part 33.
  • the flexible contact part 33 is substantially coaxial with the longitudinal axis B of the bearing sleeve 16.
  • the flexible contact part 33 is configured to center the bearing sleeve 16 on the predetermined axis, and protrudes from an axial surface (for example from the abutment surface 27) of the fixed compressor part 25 which faces towards the bearing sleeve 16.
  • the flexible contact part 33 may for example taper radially towards the electric motor 8.
  • the flexible contact part 33 may be strictly tubular, or may include longitudinal slots extending until the distal end of the flexible contact part 33 in order to improve the flexibility of the flexible contact part 33.
  • Figures 5 and 6 represent a turbo compressor 1 according to a second embodiment of the invention which differs from the first embodiment essentially in that the flexible contact area 32 is formed by several flexible contact members 34 angularly distributed, and preferably regularly distributed, around the longitudinal axis B of the bearing sleeve 16 and provided on the fixed compressor part 25.
  • Each flexible contact member 34 may for example be a flexible contact finger or a flexible contact tab extending substantially parallely to the longitudinal axis B of the bearing sleeve 16.
  • the flexible contact members 34 may be provided on the bearing sleeve 16, and for example on the sleeve part 19.
  • Figure 7 represents a turbo compressor 1 according to a third embodiment of the invention which differs from the first embodiment essentially in that the fixed compressor part 25 includes a fixed compressor body 25.1 and a flexible part 25.2 distinct from the fixed compressor body 25.1 and secured to the fixed compressor body 25.1, and in that the flexible contact 33 is defined by the flexible part 25.2.
  • Figure 8 represents a turbo compressor 1 according to a fourth embodiment of the invention which differs from the first embodiment essentially in that the flexible contact part 33 is provided on the sleeve part 19 and in that the outer circumferential surface 29 of the bearing sleeve 16 is partially defined by the flexible contact part 33.
  • the bearing sleeve 16 includes an annular groove 35 formed in the axial end face 20 and extending around the longitudinal axis B of the bearing sleeve 16, and the flexible contact part 33 is internally delimited by the annular groove 35.
  • 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.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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  • Structures Of Non-Positive Displacement Pumps (AREA)
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Abstract

The turbo compressor includes a drive shaft (3); at least one impeller connected to the drive shaft (3); an electrical motor configured to drive in rotation the drive shaft (3) and having a rotor connected to the drive shaft (3); a thrust bearing arrangement configured to limit an axial movement of the drive shaft (3); a bearing sleeve (16) configured to rotatably support the drive shaft (3), the bearing sleeve (16) including an axial end face (20) which faces towards the at least one impeller and a contact surface (23) which is located at the axial end face (20) of the bearing sleeve (16) and which is configured to cooperate with the thrust bearing arrangement; and a fixed compressor part (25) configured to center the bearing sleeve (16), the fixed compressor part (25) including a radial inner surface (28) configured to cooperate with an outer circumferential surface (29) of the bearing sleeve (16). A flexible contact area (32) is formed at an interface between the outer circumferential surface (29) of the bearing sleeve (16) and the radial inner surface (28) of the fixed compressor part (25).

Description

A turbo compressor having a flexible contact area between a bearing sleeve and a fixed compressor part
Field of the invention
The present invention relates to a turbo compressor, and particularly to a refrigeration turbo compressor.
Background of the invention
As known, a refrigeration turbo compressor may include:
- a drive shaft including a first axial end portion and a second axial end portion opposite to the first axial end portion,
- at least one compression stage configured to compress a refrigerant, the at least one compression stage including at least one impeller connected to the first axial end portion of the drive shaft,
- an electrical motor configured to drive in rotation the drive shaft about a rotation axis, the electrical motor including a stator and a rotor, the rotor being connected to the second axial end portion of the drive shaft,
- a thrust bearing arrangement configured to limit an axial movement of the drive shaft during operation,
- a bearing sleeve having a longitudinal axis and being located between the electrical motor and the at least one impeller, the bearing sleeve surrounding the drive shaft and being configured to rotatably support the drive shaft, the bearing sleeve including an axial end face which faces towards the at least one impeller and a contact surface which is located at the axial end face of the bearing sleeve and which is oriented perpendicularly with respect to the longitudinal axis of the bearing sleeve, the contact surface being configured to cooperate with the thrust bearing arrangement, and
- a fixed compressor part configured to center the bearing sleeve on a predetermined axis, the fixed compressor part including a radial inner surface configured to cooperate with an outer circumferential surface of the bearing sleeve.
The thrust bearing arrangement particularly includes:
- a thrust bearing member arranged on the outer surface of the drive shaft, the thrust bearing member extending radially outwardly with respect to the drive shaft, - a first axial bearing plate having an annular ring shape, the first axial bearing plate having a first surface and a second surface opposite to the first surface of the first axial bearing plate,
- a second axial bearing plate having an annular ring shape, the second axial bearing plate having a first surface axially facing the first axial bearing plate and a second surface opposite to the first surface of the second axial bearing plate, and
- a spacer ring being clamped between the first surfaces of the first and second axial bearing plates at radial outer portions of the first and second axial bearing plates, radial inner portions of the first and second axial bearing plates defining a space in which extends the thrust bearing member.
In operation, the contact surface of the bearing sleeve abuts the second surface of the second axial bearing plate and the thrust bearing arrangement cooperates with the first surfaces of the first and second axial bearing plates in order to limit an axial movement of the drive shaft.
However the centering of the bearing sleeve by the fixed compressor part induces radial deformations of the bearing sleeve during assembly of the turbo compressor, and thus induces deformations of the axial end face of the bearing sleeve. Further the axial end face of the bearing sleeve is also deformed due to thermal expansion gradients oriented in a radial direction occurring during operation of the turbo compressor.
Such a deformation of the axial end face of the bearing sleeve may induce deformations of the first and second axial bearing plates, and thus of the gas films in the thrust bearing arrangement when the latter is a gas thrust bearing arrangement.
Consequently, the centering of the bearing sleeve by the fixed compressor part may deteriorate the parallel positioning of the first and second axial bearing plates, and may thus lead to seizure of the thrust bearing arrangement and shortened lifetime of the turbo compressor. In addition, deformations of the axial end face of the bearing sleeve does not necessarily lead to a seizure but can also lead to an instability of the thrust bearing arrangement, which causes the generation of vibrations of the drive shaft and thus contacts of the latter with static parts of the turbo compressor leading to scratches or breaking of the drive shaft.
Summary of the invention It is an object of the present invention to provide an improved turbo compressor which can overcome the drawbacks encountered in conventional turbo compressors.
Another object of the present invention is to provide a turbo compressor which is reliable, and which is particularly not subjected to the above-mentioned deformations.
According to the invention such a turbo compressor including:
- a drive shaft including a first axial end portion and a second axial end portion opposite to the first axial end portion,
- at least one compression stage configured to compress a refrigerant, the at least one compression stage including at least one impeller connected to the first axial end portion of the drive shaft,
- an electrical motor configured to drive in rotation the drive shaft about a rotation axis, the electrical motor including a stator and a rotor, the rotor being connected to the second axial end portion of the drive shaft,
- a thrust bearing arrangement configured to limit an axial movement of the drive shaft during operation,
- a bearing sleeve having a longitudinal axis and being located between the electrical motor and the at least one impeller, the bearing sleeve surrounding the drive shaft and being configured to rotatably support the drive shaft, the bearing sleeve including an axial end face which faces towards the at least one impeller and a contact surface which is located at the axial end face of the bearing sleeve and which is configured to cooperate with the thrust bearing arrangement, and
- a fixed compressor part configured to center the bearing sleeve on a predetermined axis, the fixed compressor part including a radial inner surface configured to cooperate with an outer circumferential surface of the bearing sleeve, wherein a flexible contact area is formed at an interface between the outer circumferential surface of the bearing sleeve and the radial inner surface of the fixed compressor part.
Such a configuration of the turbo compressor allows a radial deformation of the flexible contact area between the fixed compressor part and the bearing sleeve, and thus avoids or at least strongly reduces radial deformations of the bearing sleeve and therefore deformations of the axial end face of the bearing sleeve.
Consequently, the configuration of the turbo compressor according to the present invention avoids a seizure or an unstability of the thrust bearing arrangement, and therefore improves the reliability of the turbo compressor and increases the lifetime of the turbo compressor.
The turbo compressor may also include one or more of the following features, taken alone or in combination.
According to an embodiment of the invention, the flexible contact area is flexible at least in a radial direction.
According to an embodiment of the invention, the flexible contact area is configured to avoid deformation of the axial end face of the bearing sleeve due to mechanical loads from initial assembling of the turbo compressor and/or due to thermal expansion gradients oriented in a radial direction during operation of the turbo compressor.
According to an embodiment of the invention, the flexible contact area is provided on the bearing sleeve and/or the fixed compressor part.
According to an embodiment of the invention, the flexible contact area is provided on the bearing sleeve and is separated from the axial end face of the bearing sleeve.
According to an embodiment of the invention, the flexible contact area is formed by a flexible contact part provided on the bearing sleeve or on the fixed compressor part, the flexible contact part being substantially tubular and being substantially coaxial with the longitudinal axis of the bearing sleeve.
According to an embodiment of the invention, the flexible contact part is provided on the fixed compressor part and the radial inner surface of the fixed compressor part is provided on the flexible contact part. Therefore during assembly of the turbo compressor, the flexible contact part being greatly less stiff than the bearing sleeve, it will deform and thus strongly reduces the deformation of the bearing sleeve for an equivalent interference between the fixed compressor part and the bearing sleeve.
According to an embodiment of the invention, the flexible contact part is configured to center the bearing sleeve on the predetermined axis.
According to an embodiment of the invention, the flexible contact part protrudes from an axial surface of the fixed compressor part which faces towards the bearing sleeve.
According to an embodiment of the invention, the flexible contact part tapers radially towards the electric motor.
According to an embodiment of the invention, the flexible contact part is provided on the bearing sleeve and the outer circumferential surface of the bearing sleeve is at least partially provided on the flexible contact part. Such a configuration of the flexible contact part allows to separate the flexible contact area from the contact surface of the bearing sleeve. Therefore, during assembly of the turbo compressor, the flexible contact part will deform, but without impacting the contact surface of the bearing sleeve and thus the thrust bearing arrangement.
According to an embodiment of the invention, the bearing sleeve includes an annular groove formed in the axial end face of the bearing sleeve and extending around the longitudinal axis of the bearing sleeve, the flexible contact part being internally delimited by the annular groove.
According to an embodiment of the invention, the flexible contact area is formed by several flexible contact members angularly distributed around the longitudinal axis of the bearing sleeve and provided on the bearing sleeve or on the fixed compressor part.
According to an embodiment of the invention, the flexible contact members are regularly distributed around the longitudinal axis of the bearing sleeve.
According to an embodiment of the invention, each flexible contact member extends substantially parallely to the longitudinal axis of the bearing sleeve.
According to an embodiment of the invention, each flexible contact member is a flexible contact finger.
According to an embodiment of the invention, the axial end face of the bearing sleeve is planar and oriented perpendicularly with respect to the longitudinal axis of the bearing sleeve.
According to an embodiment of the invention, the bearing sleeve includes:
- a radial bearing part which is tubular and which is configured to rotatably support the drive shaft,
- a sleeve part surrounding the radial bearing part and including the axial end face of the bearing sleeve, and
- an annular gap formed between the radial bearing part and the sleeve part.
According to an embodiment of the invention, the flexible contact part is provided on the sleeve part.
According to an embodiment of the invention, the flexible contact members are provided on the sleeve part.
According to an embodiment of the invention, the annular groove is provided on the sleeve part. According to an embodiment of the invention, the radial bearing part is a radial gas bearing part.
According to an embodiment of the invention, the radial bearing part has an inner diameter which is larger than an outer diameter of a bearing portion of the drive shaft which is surrounded by the radial bearing part, the bearing portion and the radial bearing part defining an annular gaseous chamber when the drive shaft is rotating.
According to an embodiment of the invention, the radial bearing part and the sleeve part are concentrically arranged.
According to an embodiment of the invention, the sleeve part is connected to the radial bearing part through a connecting part which is positioned away from the axial end face of the bearing sleeve.
According to an embodiment of the invention, the sleeve part and the radial bearing part are made in one piece.
According to an embodiment of the invention, the sleeve part is shorter than the radial bearing part along the longitudinal axis of the bearing sleeve.
According to an embodiment of the invention, the thrust bearing arrangement is a gas thrust bearing arrangement.
According to an embodiment of the invention, the thrust bearing arrangement is located between the at least one compression stage and the bearing sleeve.
According to an embodiment of the invention, the thrust bearing arrangement includes a thrust bearing member arranged on the outer surface of the drive shaft, the thrust bearing member extending substantially radially outwardly with respect to the drive shaft.
According to an embodiment of the invention, the thrust bearing arrangement includes:
- a first axial bearing plate having an annular ring shape, the first axial bearing plate having a first surface and a second surface opposite to the first surface of the first axial bearing plate,
- a second axial bearing plate having an annular ring shape, the second axial bearing plate having a first surface axially facing the first axial bearing plate and a second surface opposite to the first surface of the second axial bearing plate, the second surface of the second axial bearing plate abutting against the contact surface of the bearing sleeve, and - a spacer ring being clamped between the first surfaces of the first and second axial bearing plates at radial outer portions of the first and second axial bearing plates, the spacer ring defining an axial distance between the first and second axial bearing plates.
According to an embodiment of the invention, the first and second axial bearing plates are parallel to each other.
According to an embodiment of the invention, the thrust bearing member extends into a space between radial inner portions of the first surfaces of the first and second axial bearing plates.
According to an embodiment of the invention, the bearing sleeve includes a cooling area formed in the outer circumferential surface of the bearing sleeve, and particularly of the sleeve part, and intended for the passage of a refrigerant so as to dissipate heat from the bearing sleeve.
According to an embodiment of the invention, the cooling area includes at least one annular cooling channel formed in the outer circumferential surface of the bearing sleeve and extending around the longitudinal axis of the bearing sleeve.
According to an embodiment of the invention, the turbo compressor includes an elastic element configured to axially bias the thrust bearing arrangement, and particularly the first and second axial bearing plates and the spacer ring, with a predetermined force against the contact surface of the bearing sleeve.
According to an embodiment of the invention, the elastic element is arranged between the second surface of the first axial bearing plate and the fixed compressor part.
According to an embodiment of the invention, the elastic element is an annular spring washer, preferably of the Belleville type.
According to an embodiment of the invention, the at least one compression stage includes a first and a second compression stage configured to compress a refrigerant, the first and second compression stages respectively including a first and a second impeller, the first and second impellers being connected to the first axial end portion of the drive shaft.
According to an embodiment of the invention, each of the first and second impellers has a front-side and a back-side, the first and second impellers being arranged in a back-to-back configuration.
According to an embodiment of the invention, the turbo compressor includes an hermetic casing, the drive shaft being rotatably arranged within the hermetic casing. According to an embodiment of the invention, the second axial end portion of the drive shaft includes a rotor attachment part including an axial bore receiving the rotor.
According to an embodiment of the invention, the fixed compressor part includes an abutment surface against which abuts the bearing sleeve, and for example the contact surface of the bearing sleeve.
According to an embodiment of the invention, the bearing sleeve is immobilized axially with respect to the fixed compressor part.
According to an embodiment of the invention, the turbo compressor further includes a securing member axially tightening the bearing sleeve against the fixed compressor part, and for example against the abutment surface of the fixed compressor part.
According to an embodiment of the invention, the bearing sleeve is a one-piece bearing sleeve.
These and other advantages will become apparent upon reading the following description in view of the drawing attached hereto representing, as non limiting examples, embodiments of a 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 section view of a turbo compressor according to a first embodiment of the invention.
Figure 2 is an enlarged view of a detail of figure 1.
Figure 3 is a longitudinal section view of a fixed compressor part of the turbo compressor of figure 1.
Figure 4 is a perspective view of the fixed compressor part of figure 3.
Figure 5 is a longitudinal section view of a fixed compressor part of a turbo compressor according to a second embodiment of the invention.
Figure 6 is a perspective view of the fixed compressor part of figure 5.
Figure 7 is a longitudinal section view of a fixed compressor part of a turbo compressor according to a third embodiment of the invention. Figure 8 is a longitudinal section view of a turbo compressor according to a fourth embodiment of the invention.
Figure 9 is a longitudinal section view of a bearing sleeve of the turbo compressor of figure 8.
Figure 10 is a perspective view of the bearing sleeve of figure 9.
Detailed description of the invention
Figures 1 to 4 represent a refrigeration turbo compressor 1 according to a first embodiment of the invention, which may be for example a two-stage refrigeration turbo compressor.
The turbo compressor 1 includes an hermetic casing 2 and a drive shaft 3 which is rotatably arranged within the hermetic casing 2 and which extends along a longitudinal axis A. The drive shaft 3 includes a first axial end portion 4, a second axial end portion 5 opposite to the first axial end portion 4, and an intermediate portion 6 located between the first and second axial end portions 4, 5.
The turbo compressor 1 further includes at least one impeller 7 connected to the first axial end portion 4 of the drive shaft 3, and configured to compress a refrigerant. The turbo compressor 1 may for example include two impellers 7 arranged in a back-to-back configuration.
The turbo compressor 1 also includes an electrical motor 8 configured to drive in rotation the drive shaft 3 about the longitudinal axis A. The electrical motor 8 includes a stator 9 and a rotor 10. Advantageously, the rotor 10 is connected to the second axial end portion 5 of the drive shaft 3. To this end, the second axial end portion 5 may include an axial bore 11 within which is arranged the rotor 10. The rotor 10 may for example be firmly fitted, such as press-fitted or shrink fitted, within the axial bore 11.
The turbo compressor 1 further includes a thrust bearing arrangement, also named axial bearing arrangement, arranged between the at least one impeller 7 and the electrical motor 8 and configured to limit an axial movement of the drive shaft 3 during operation. The thrust bearing arrangement is advantageously a gas thrust bearing arrangement.
The thrust bearing arrangement includes a thrust bearing member 12 arranged on an outer surface of the intermediate portion 6 of the drive shaft 3 and extending radially outwardly with respect to the drive shaft 3. The thrust bearing member 12 has a flat disc shape, and includes a first axial end face 12.1 and a second axial end face 12.2 opposite to the first axial end face 12.1.
The thrust bearing arrangement also includes a first axial bearing plate 13 and a second axial bearing plate 14 each having an annular ring shape, and being arranged in parallel. The first axial bearing plate 13 has a first surface 13.1 axially facing the second axial bearing plate 14 and a second surface 13.2 opposite to the first surface 13.1, while the second axial bearing plate 14 has a first surface 14.1 axially facing the first axial bearing plate 13 and a second surface 14.2 opposite to the first surface 14.1.
The thrust bearing arrangement further includes a spacer ring 15 surrounding the thrust bearing member 12, and being clamped between the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 at radial outer portions of the first and second axial bearing plates 13, 14. The spacer ring 15 defines an axial distance between the first and second axial bearing plates 13, 14, said axial distance being slightly greater than the width of the thrust bearing member 12.
The radial inner portions of the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 define a space in which extends the thrust bearing member 12. Particularly, the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 are respectively configured to cooperate with the first and second axial end faces 12.1, 12.2 of the thrust bearing member 12.
Advantageously, the turbo compressor 1 is configured so that gas refrigerant is introduced between the thrust bearing member 12 and the first surfaces 13.1, 14.1 of the first and second axial bearing plates 13, 14 to form a gas thrust bearing for the drive shaft 3.
The turbo compressor 1 also includes a bearing sleeve 16, also named bearing housing, which extends along the intermediate portion 6 of the drive shaft 3 and which is located between the thrust bearing arrangement and the electrical motor 8. The bearing sleeve 16 may be a one-piece bearing sleeve, or may be made from separated parts assembled together.
The bearing sleeve 16 particularly includes:
- a radial bearing part 18 which is tubular and which surrounds the intermediate portion 6 of the drive shaft 3, the radial bearing part 18 being configured to rotatably support the drive shaft 3,
- a sleeve part 19 surrounding the radial bearing part 18 and including an axial end face 20 which is planar and which extends perpendicularly to a longitudinal axis B of the bearing sleeve 16, the axial end face 20 facing towards the thrust bearing arrangement, and
- an annular gap 21 formed between the radial bearing part 18 and the sleeve part 19.
According to the first embodiment of the invention, the radial bearing part 18 and the sleeve part 19 are concentrically arranged, and the sleeve part 19 is connected to the radial bearing part 18 through a connecting part P which is away from the axial end face 20, and which is for example positioned substantially at a center of the axial length of the radial bearing part 18. The sleeve part 19 may be shorter than the radial bearing part 18 along the longitudinal axis B of the bearing sleeve 16.
Advantageously, the radial bearing part 18 includes first and second radial bearing surfaces 18.1, 18.2 located on each side of the connecting part P and configured to cooperate with the drive shaft 3. Each of the first and second radial bearing surfaces 18.1, 18.2 has advantageously an inner diameter which is larger than an outer diameter of a bearing portion 22 provided on the intermediate portion 6 of the drive shaft 3 and which is surrounded by the radial bearing part 18, such that the bearing portion 22 and each of the first and second radial bearing surfaces 18.1, 18.2 define an annular gaseous chamber when the drive shaft 3 is rotating. The turbo compressor 1 is particularly configured so that gas refrigerant is introduced between the bearing portion 22 of the drive shaft 3 and the inner surface of the radial bearing part 18 to form a radial gas bearing for the drive shaft 3.
The bearing sleeve 16 further includes a contact surface 23 located at the axial end face 20 of sleeve part 19, and the second surface 14.2 of the second axial bearing plate 14 abuts against the contact surface 23.
Advantageously, the bearing sleeve 16 is axially immobilized with respect to a fixed compressor part 25 of the turbo compressor 1. The turbo compressor 1 may therefore include a securing member 26 axially tightening the bearing sleeve 16 against the fixed compressor part 25, and more particularly against an abutment surface 27 provided on an axial surface of the fixed compressor part 25. The securing member 26 may be secured, for example by screwing, to the hermetic casing 2 or to the fixed compressor part 25. Particularly, the contact surface 23 of the bearing sleeve 16 abuts against the abutment surface 27.
The fixed compressor part 25 is particularly configured to center the bearing sleeve 16 on a predetermined axis which is coaxial with the rotation axis of the drive shaft 3. Thus the fixed compressor part 25 also includes a radial inner surface 28 configured to cooperate with an outer circumferential surface 29 of the bearing sleeve 16, and particularly of the sleeve part 19.
The fixed compressor part 25 may for example include a tubular part 30 defining an inner housing in which are received the first and second axial bearing plates 13, 14 and the spacer ring 15.
The turbo compressor 1 further includes an elastic element 31 arranged between the second surface 13.2 of the first axial bearing plate 13 and the fixed compressor part 25. The elastic element 31 axially biases the first and second axial bearing plates 13, 14 and the spacer ring 15 with a predetermined force, for example in the range of 1000 to 2000 N, against the contact surface 23 of the bearing sleeve 16. Advantageously, the elastic element 31 is an annular spring washer, preferably of the Belleville type, coaxially arranged with the bearing sleeve 16 and the drive shaft 3. The elastic element 31 is advantageously arranged in an annular recess formed in an axial surface of the fixed compressor part 25, and is in contact with a radial outer portion of the second surface 13.2 of the first axial bearing plate 13.
The elastic element 31 allows, notably when a thermal expansion occurs in the turbo compressor 1, an axial sliding of the first and second axial bearing plates 13, 14 and of the spacer ring 15 with respect to the fixed compressor part 25, and thus avoids deformations of said parts which could lead to a shortened lifetime of the turbo compressor 1.
The bearing sleeve 16 further includes a cooling area 36 formed in the outer circumferential surface 29 of the sleeve part 19. The cooling area 36 may for example include an annular cooling channel 37 formed in the outer circumferential surface 29 of the sleeve part 19 and extending around the longitudinal axis B of the bearing sleeve 16, the annular cooling channel 37 being intended for the passage of a refrigerant so as to dissipate heat from the bearing sleeve 16. Furthermore the turbo compressor 1 includes a flexible contact area 32 which is formed at an interface between the outer circumferential surface 29 of the bearing sleeve 16 and the radial inner surface 28 of the fixed compressor part 25, and which is flexible at least in a radial direction. The flexible contact area 32 is particularly configured to avoid deformation of the axial end face 20 of the bearing sleeve 16 due to mechanical loads from initial assembling of the turbo compressor 1 and/or due to thermal expansion gradients oriented in a radial direction during operation of the turbo compressor 1.
According to the first embodiment of the invention, the flexible contact area 32 is formed by a flexible contact part 33 which is provided on the fixed compressor part 25 and which is substantially tubular, and the radial inner surface 28 is provided on the flexible contact part 33. Advantageously, the flexible contact part 33 is substantially coaxial with the longitudinal axis B of the bearing sleeve 16.
According to the first embodiment of the invention, the flexible contact part 33 is configured to center the bearing sleeve 16 on the predetermined axis, and protrudes from an axial surface (for example from the abutment surface 27) of the fixed compressor part 25 which faces towards the bearing sleeve 16. The flexible contact part 33 may for example taper radially towards the electric motor 8.
It should be noted that the flexible contact part 33 may be strictly tubular, or may include longitudinal slots extending until the distal end of the flexible contact part 33 in order to improve the flexibility of the flexible contact part 33.
Figures 5 and 6 represent a turbo compressor 1 according to a second embodiment of the invention which differs from the first embodiment essentially in that the flexible contact area 32 is formed by several flexible contact members 34 angularly distributed, and preferably regularly distributed, around the longitudinal axis B of the bearing sleeve 16 and provided on the fixed compressor part 25. Each flexible contact member 34 may for example be a flexible contact finger or a flexible contact tab extending substantially parallely to the longitudinal axis B of the bearing sleeve 16. However, according to another embodiment of the invention, the flexible contact members 34 may be provided on the bearing sleeve 16, and for example on the sleeve part 19.
Figure 7 represents a turbo compressor 1 according to a third embodiment of the invention which differs from the first embodiment essentially in that the fixed compressor part 25 includes a fixed compressor body 25.1 and a flexible part 25.2 distinct from the fixed compressor body 25.1 and secured to the fixed compressor body 25.1, and in that the flexible contact 33 is defined by the flexible part 25.2.
Figure 8 represents a turbo compressor 1 according to a fourth embodiment of the invention which differs from the first embodiment essentially in that the flexible contact part 33 is provided on the sleeve part 19 and in that the outer circumferential surface 29 of the bearing sleeve 16 is partially defined by the flexible contact part 33.
Advantageously, the bearing sleeve 16 includes an annular groove 35 formed in the axial end face 20 and extending around the longitudinal axis B of the bearing sleeve 16, and the flexible contact part 33 is internally delimited by the annular groove 35. 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 turbo compressor (1) including:
- a drive shaft (3) including a first axial end portion (4) and a second axial end portion (5) opposite to the first axial end portion (4),
- at least one compression stage configured to compress a refrigerant, the at least one compression stage including at least one impeller (7) connected to the first axial end portion (4) of the drive shaft (3),
- an electrical motor (8) configured to drive in rotation the drive shaft (3) about a rotation axis, the electrical motor including a stator (9) and a rotor (10), the rotor (10) being connected to the second axial end portion (5) of the drive shaft (3),
- a thrust bearing arrangement configured to limit an axial movement of the drive shaft (3) during operation,
- a bearing sleeve (16) having a longitudinal axis (B) and being located between the electrical motor (8) and the at least one impeller (7), the bearing sleeve (16) surrounding the drive shaft (3) and being configured to rotatably support the drive shaft (3), the bearing sleeve (16) including an axial end face (20) which faces towards the at least one impeller (7) and a contact surface (23) which is located at the axial end face (20) of the bearing sleeve (16) and which is configured to cooperate with the thrust bearing arrangement, and
- a fixed compressor part (25) configured to center the bearing sleeve (16) on a predetermined axis, the fixed compressor part (25) including a radial inner surface (28) configured to cooperate with an outer circumferential surface (29) of the bearing sleeve (16),
wherein a flexible contact area (32) is formed at an interface between the outer circumferential surface (29) of the bearing sleeve (16) and the radial inner surface (28) of the fixed compressor part (25).
2. The turbo compressor (1) according to claim 1, wherein the flexible contact area (32) is configured to avoid deformation of the axial end face (20) of the bearing sleeve (16) due to mechanical loads from initial assembling of the turbo compressor (1) and/or due to thermal expansion gradients oriented in a radial direction during operation of the turbo compressor (1).
3. The turbo compressor (1) according to claim 1 or 2, wherein the flexible contact area (32) is provided on the bearing sleeve (16) and/or the fixed compressor part (25).
4. The turbo compressor (1) according to any one of claims 1 to 3, wherein the flexible contact area (32) is formed by a flexible contact part (33) provided on the bearing sleeve (16) or on the fixed compressor part (25), the flexible contact part (33) being substantially tubular and being substantially coaxial with the longitudinal axis (B) of the bearing sleeve (16).
5. The turbo compressor (1) according to claim 4, wherein the flexible contact part (33) is provided on the fixed compressor part (25) and the radial inner surface (28) of the fixed compressor part (25) is provided on the flexible contact part (33).
6. The turbo compressor (1) according to claim 5, wherein the flexible contact part (33) is configured to center the bearing sleeve (16) on the predetermined axis.
7. The turbo compressor (1) according to claim 5 or 6, wherein the flexible contact part (33) protrudes from an axial surface of the fixed compressor part (25) which faces towards the bearing sleeve (16).
8. The turbo compressor (1) according to claim 4, wherein the flexible contact part (33) is provided on the bearing sleeve (16) and the outer circumferential surface (29) of the bearing sleeve (16) is at least partially provided on the flexible contact part (33).
9. The turbo compressor (1) according to claim 8, wherein the bearing sleeve (16) includes an annular groove (35) formed in the axial end face (20) of the bearing sleeve (16) and extending around the longitudinal axis (B) of the bearing sleeve (16), the flexible contact part (33) being internally delimited by the annular groove (35).
10. The turbo compressor (1) according to any one of claims 1 to 3, wherein the flexible contact area (32) is formed by several flexible contact members (34) angularly distributed around the longitudinal axis (B) of the bearing sleeve (16) and provided on the bearing sleeve (16) or on the fixed compressor part (25).
11. The turbo compressor (1) according to any one of claims 1 to 10, wherein the bearing sleeve (16) includes:
- a radial bearing part (18) which is tubular and which is configured to rotatably support the drive shaft (3),
- a sleeve part (19) surrounding the radial bearing part (18) and including the axial end face (20) of the bearing sleeve (16), and
- an annular gap (21) formed between the radial bearing part (18) and the sleeve part (19).
12. The turbo compressor (1) according to any one of claims 1 to 11, wherein the thrust bearing arrangement includes a thrust bearing member (12) arranged on the outer surface of the drive shaft (3), the thrust bearing member (12) extending substantially radially outwardly with respect to the drive shaft (3).
13. The turbo compressor (1) according to any one of claims 1 to 12, wherein the thrust bearing arrangement includes:
- a first axial bearing plate (13) having an annular ring shape, the first axial bearing plate (13) having a first surface (13.1) and a second surface (13.2) opposite to the first surface (13.1) of the first axial bearing plate (13),
- a second axial bearing plate (14) having an annular ring shape, the second axial bearing plate (14) having a first surface (14.1) axially facing the first axial bearing plate (13) and a second surface (14.2) opposite to the first surface (14.1) of the second axial bearing plate (14), the second surface (14.2) of the second axial bearing plate (14) abutting against the contact surface (23) of the bearing sleeve (16), and
- a spacer ring (15) being clamped between the first surfaces (13.1, 14.1) of the first and second axial bearing plates (13, 14) at radial outer portions of the first and second axial bearing plates (13, 14), the spacer ring (15) defining an axial distance between the first and second axial bearing plates (13, 14).
14. The turbo compressor (1) according to any one of claims 1 to 13, wherein the bearing sleeve (16) includes a cooling area (36) formed in the outer circumferential surface (29) of the bearing sleeve (16) and intended for the passage of a refrigerant so as to dissipate heat from the bearing sleeve (16).
PCT/EP2019/072400 2018-08-22 2019-08-21 A turbo compressor having a flexible contact area between a bearing sleeve and a fixed compressor part WO2020039006A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1857594A FR3085187B1 (en) 2018-08-22 2018-08-22 A TURBOCHARGER HAVING A FLEXIBLE CONTACT ZONE BETWEEN A BEARING SLEEVE AND A FIXED COMPRESSOR PART.
FR1857594 2018-08-22

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WO2020039006A1 true WO2020039006A1 (en) 2020-02-27

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GB1296280A (en) * 1969-08-21 1972-11-15
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