US3756738A - Centrifugal pump with differential thermal expansion relief means - Google Patents

Centrifugal pump with differential thermal expansion relief means Download PDF

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Publication number
US3756738A
US3756738A US00191863A US3756738DA US3756738A US 3756738 A US3756738 A US 3756738A US 00191863 A US00191863 A US 00191863A US 3756738D A US3756738D A US 3756738DA US 3756738 A US3756738 A US 3756738A
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United States
Prior art keywords
shaft
hubs
impellers
hub
impeller
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Expired - Lifetime
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US00191863A
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English (en)
Inventor
W Lee
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Rexnord Industries LLC
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Clarkson Industries Inc
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Publication date
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/02—Blade-carrying members, e.g. rotors
    • F01D5/025—Fixing blade carrying members on shafts
    • 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
    • F04D29/266—Rotors specially for elastic fluids mounting compressor rotors on shafts

Definitions

  • ABSTRACT A centrifugal blower having one or more impellers mounted on a shaft for rotation therewith with the impellers and shaft being made of materials having different thermal coefficients of expansion and the impeller hubs being provided with means for relieving compressive stresses generated by differential expansion.
  • the stress relieving means comprises disk-shaped channels formed in the impeller hubs to permit the central portions of the impeller hubs to be resiliently deformed to relieve the compressive stresses, thereby avoiding shaft distortion which produces vibration of the blower.
  • This invention relates to centrifugal pumps, and more particularly, to a means for relieving axial stresses due to differential thermal expansion of the impellers of such a pump and the drive shaft on which they are mounted for rotation. While the present invention is adapted to be used in all types of centrifugal pumps including liquid pumps, centrifugal blowers, and centrifugal compressors, it will, for cnvenience, be described as applied to a typical centrifugal blower.
  • Multi-stage centrifugal blowers generally comprise a housing with inlet and outlet ports and having a drive shaft mounted for horizontal rotation in bearings supported in the housing. Mounted on and secured to the drive shaft for rotation therewith there are a series of impellers having radial passages therein which cooperate with transfer conduits formed in the housing to transfer the pumped fluid from stage to stage of the blower.
  • the hub portions of the impellers may directly abut one another or may be separated by spacer rings which maintain a predetermined spacing between the impellers.
  • the impellers, either with or without spacing rings therebetween, are locked together against axial movement relative to the drive shaft by suitable locking means such as, for example, locking nuts on the drive shaft.
  • the impellers and drive shaft may be made of steel to achieve the desired structural strength and rigidity whereas the impellers may be made of aluminum to reduce their weight.
  • the blower When in operation the blower generates heat due to compression of the gas, recirculation and disk friction. Since aluminum has a larger coefficient of thermal expansion than steel, the increased temperature during operation of the blower tends to generate a compressive stress in the hub portions of the impellers.
  • centrifugal pump including a simple and effective means for relieving compressive stresses that may be generated in the hub portions of the impellers of the pump during operation thereof.
  • a multi-stage centrifugal blower including means for eliminating vibration of the rotor thereof due to deformation of the drive shaft caused by axial stresses generated in' the hub portions of the impellers of the rotor.
  • FIG. 1 is a side view of a 3-stage centrifugal blower, partially in section, to show the arrangement of the impellers on the drive shaft and the pressure-relieving channels in the hubs of the impellers;
  • FIG. 2 is an enlarged section of one of the impeller hubs further showing the pressure relieving channel therein.
  • the numeral 10 generally designates a conventional 3-stage centrifugal blower having an inlet 12, an outlet 14 and a horizontal drive shaft 16 driven by a suitable prime mover (not shown).
  • FIG. 1 the lower portion of the blower casing is broken away to show the arrangement of the impellers and transfer conduits therein.
  • Mounted on shaft 16 are three impellers, namely, a first stage impeller 18, a second stage impeller 20 and a third stage impeller 22.
  • the impeller 18 is secured to shaft 16 for rotation therewith by a key 24.
  • Impellers 20 and 22 are similarly keyed to the shaft 16 but the keys are notshown in FIG. 1.
  • the impellers 18 to 22 have the usual radial passages 18a, 20a and 22a formed therein and hub portions 18b, 20b and 22b adjacent to the shaft 16.
  • the hubs of the impellers are separated by spacer rings which are slideably mounted on shaft 16. More particularly, there is a spacer ring 26 that abuts the left-hand or front face of the hub of impeller 22 and right-hand or rear face of the hub of impeller 20. Similarly, there is a spacer 28 that abuts the I front face of the hub of impeller 20 and the rear face of the hub of impeller l8. A third spacer ring 30 abuts at one end the front face of the hub of impeller 18 and at its other end abuts a shoulder 32 formed by an enlarged portion 34 of the shaft 16.
  • the spacers and impeller hubs are locked against axial movement in relation to shaft 16 by the shoulder 32 at one end of the space-hub assembly and by a lock nut 36 threaded onto shaft 16 at the other end of the assembly.
  • the impeller hubs are in some cases so designed that they abut one another without the intervening spacer rings.
  • the air discharged from passage 18a is conducted by a transfer conduit 38 formed in the blower casing to the inlet of radial passage 20a of impeller 20.
  • the air is further compressed as it passes through the passage 20a of second stage impeller 20 and is then conducted by transfer conduit 40 to the inlet of radial passage 22a of third stage impeller 22. After being further compressed in passage 220, the air flows through a conduit 42 to the blower output 14.
  • the shaft 16 and impellers 18, 20' and 22 are customary of different materials.
  • the shaft may be made of steel and the impellers of cast aiuminum or bronze which have different thermal expansion coefiicients.
  • heat is generated by compression of the gas and other factors.
  • axial compressive stresses are generated in the hubs which tend to distort the drive shaft and produces undesirable vibrations of the rotor assembly.
  • these stresses are relieved by making a portion of the hub of at least one of the impellers resiliently deformable.
  • FIG. 2 of the drawing which is a greatly enlarged view of the hub b of impeller 20, there is formed at the internal periphery of the hub a diskshaped channel 44 that extends radially outward into the hub 20b.
  • the channel 44 is located relatively close to the rear face 46 of the hub.
  • each of the impellers need be provided with a stress-relieving channel as indicated in FIG. 1.
  • the present invention provides a structure capable of achieving the objects set forth at the beginning of the present specification.
  • the channels 44 permit the central rear portions of the impellers to be resiliently deflected inwardly to relieve such stresses.
  • shaft distortion and the consequent undesirable vibration of the rotor are avoided.
  • the faces of the impeller hubs may not be precisely perpendicular to the axis of the shaft and stresses tending to bend the shaft may be generated as a result of these machining imperfections. Such bending stresses may occur even when there is no differential thermal expansion of the impeller assembly and shaft. Such bending stresses are also achieved by the channels formed in the impeller hubs in accordance with the present invention.
  • shaft and impellers can be made of metals other than those specifically disclosed and the present structure will provide a stress-relieving function to eliminate or substantially reduce the undesirable effects of differential thermal expansion of such other metals.
  • a centrifugal blower comprising in combination a housing, a rotatable shaft mounted in said housing, a plurality of impellers within said housing having hubs mounted on and secured to said shaft for rotation therewith and locking means for locking said impeller hubs in fixed relation to one another and holding them against axial motion in respect to said shaft, said impellers being made of a material having a greater thermal coefficient of expansion than said shaft, at least one of said impeller hubs having an internal peripheral channel formed therein adjacent to said shaft to form a resilient deformable hub portion whereby axial stresses generated by differential thermal expansion of said shaft and hubs and consequent bending stresses generated in the hub portions of the impellers are relieved.
  • a centrifugal blower comprising in combination a housing, a rotatable shaft mounted in said housing, a plurality of impellers within said housing having hubs mounted on and secured to said shaft for rotation therewith and locking means for locking said impeller hubs in fixed relation to one another and holding them against axial motion in respect to said shaft, said impellers being made of a material having a greater thermal coefficient of expansion than said shaft, said impeller hubs having front faces with inlet ports formed therein and rear faces substantially perpendicular to said shaft, at least one of said hubs having a disk-shaped internal peripheral channel formed therein close to the rear face of said hub whereby the portion of said hub between said channel and the rear face of the said hub is resiliently and axially deformed to relieve axial and bending stresses generated in the hub portions of the impellers by differential thermal expansion of said hub portions and said shaft.
  • a centrifugal blower according to claim 2 wherein said channel extends radially into said hub in a direction substantially perpendicular to the rotational axis of said shaft.
  • a centrifugal blower according to claim 2 wherein spacer rings are mounted on said shaft between said impeller hubs to maintain a predetermined spacing between said hubs.
  • a centrifugal blower comprising in combination a housing, a plurality of impellers within said housing having hubs mounted on and secured to said shaft for rotation therewith, spacer rings mounted on said shaft between said impellers for maintaining a predetermined spacing between said impeller hubs and locking means on said shaft for locking said impeller hubs and spacer rings together and holding them against axial motion in respect to said shaft, said impellers being made of a material having a greater thermal coefficient of expansion than said shaft, said impeller hubs having front faces with inlet ports formed therein and rear faces substantially perpendicular to said shaft, said hubs having internal peripheral channels formed therein close to the rear faces of said hubs, whereby the portion of said hubs between said channels and the rear faces of said hubs are resiliently and axially deformed to relieve axial and bending stresses generated in the hub portions of the impellers by differential thermal expansion of said hub portions and said shaft.
  • a centrifugal blower according to claim 2 wherein said peripheral channel extends radially into its hub to a point axially opposite the inlet port of said hub.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
US00191863A 1971-10-22 1971-10-22 Centrifugal pump with differential thermal expansion relief means Expired - Lifetime US3756738A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19186371A 1971-10-22 1971-10-22

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US3756738A true US3756738A (en) 1973-09-04

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Application Number Title Priority Date Filing Date
US00191863A Expired - Lifetime US3756738A (en) 1971-10-22 1971-10-22 Centrifugal pump with differential thermal expansion relief means

Country Status (5)

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US (1) US3756738A (it)
DE (1) DE2249626A1 (it)
FR (1) FR2157515A5 (it)
GB (1) GB1347616A (it)
IT (1) IT965255B (it)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4307995A (en) * 1980-02-01 1981-12-29 Rockwell International Corporation Vaneless multistage pump
US5290148A (en) * 1991-03-13 1994-03-01 Kabushiki Kaisha Toshiba High head pump-turbines
US5456577A (en) * 1994-07-28 1995-10-10 Ingersoll-Dresser Pump Company Centrifugal pump with resiliently biasing diffuser
US20050058539A1 (en) * 2003-09-12 2005-03-17 Siemens Westinghouse Power Corporation Turbine blade tip clearance control device
US20050058540A1 (en) * 2003-09-12 2005-03-17 Siemens Westinghouse Power Corporation Turbine engine sealing device
US6935838B1 (en) * 2003-03-19 2005-08-30 Hi-Bar Blowers, Inc. High pressure multi-stage centrifugal blower
US7748960B1 (en) * 2006-05-04 2010-07-06 Florida Turbine Technologies, Inc. Hub to shaft connection
CN1912395B (zh) * 2005-08-09 2011-01-19 海巴鼓风机有限公司 中速高压多级离心式鼓风机

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2572469B1 (fr) * 1984-10-31 1989-04-07 Creusot Loire Machine tournante a circulation de fluide.
CN102465889A (zh) * 2010-11-10 2012-05-23 湖北省风机厂有限公司 一种热风干燥离心鼓风机

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB114926A (it) *
GB175530A (en) * 1921-02-10 1922-02-23 Mather & Platt Ltd Improvements relating to centrifugal pumps
US2177924A (en) * 1937-07-24 1939-10-31 Timken Roller Bearing Co Wheel and axle assembly
US2383424A (en) * 1944-05-06 1945-08-21 Ingersoll Rand Co Pump
US2438867A (en) * 1945-06-01 1948-03-30 United Aircraft Corp Method of assembling shrouds on impellers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB114926A (it) *
GB175530A (en) * 1921-02-10 1922-02-23 Mather & Platt Ltd Improvements relating to centrifugal pumps
US2177924A (en) * 1937-07-24 1939-10-31 Timken Roller Bearing Co Wheel and axle assembly
US2383424A (en) * 1944-05-06 1945-08-21 Ingersoll Rand Co Pump
US2438867A (en) * 1945-06-01 1948-03-30 United Aircraft Corp Method of assembling shrouds on impellers

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4307995A (en) * 1980-02-01 1981-12-29 Rockwell International Corporation Vaneless multistage pump
US5290148A (en) * 1991-03-13 1994-03-01 Kabushiki Kaisha Toshiba High head pump-turbines
US5456577A (en) * 1994-07-28 1995-10-10 Ingersoll-Dresser Pump Company Centrifugal pump with resiliently biasing diffuser
US6935838B1 (en) * 2003-03-19 2005-08-30 Hi-Bar Blowers, Inc. High pressure multi-stage centrifugal blower
US20050058539A1 (en) * 2003-09-12 2005-03-17 Siemens Westinghouse Power Corporation Turbine blade tip clearance control device
US20050058540A1 (en) * 2003-09-12 2005-03-17 Siemens Westinghouse Power Corporation Turbine engine sealing device
US6896484B2 (en) 2003-09-12 2005-05-24 Siemens Westinghouse Power Corporation Turbine engine sealing device
US6926495B2 (en) 2003-09-12 2005-08-09 Siemens Westinghouse Power Corporation Turbine blade tip clearance control device
CN1912395B (zh) * 2005-08-09 2011-01-19 海巴鼓风机有限公司 中速高压多级离心式鼓风机
US7748960B1 (en) * 2006-05-04 2010-07-06 Florida Turbine Technologies, Inc. Hub to shaft connection

Also Published As

Publication number Publication date
IT965255B (it) 1974-01-31
GB1347616A (en) 1974-02-27
DE2249626A1 (de) 1973-04-26
FR2157515A5 (it) 1973-06-01

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