US3138318A - Turbo-molecular vacuum pump - Google Patents

Turbo-molecular vacuum pump Download PDF

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Publication number
US3138318A
US3138318A US189021A US18902162A US3138318A US 3138318 A US3138318 A US 3138318A US 189021 A US189021 A US 189021A US 18902162 A US18902162 A US 18902162A US 3138318 A US3138318 A US 3138318A
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United States
Prior art keywords
turbo
vacuum pump
blades
molecular
pump
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Expired - Lifetime
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US189021A
Inventor
Garnier Henri Louis
Rubet Leonide
Marchal Raymond Hippoly Firmin
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Safran Aircraft Engines SAS
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SNECMA SAS
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F04D19/042—Turbomolecular vacuum 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
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/321—Rotors specially for elastic fluids for axial flow pumps for axial flow compressors
    • F04D29/324—Blades
    • 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
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/52—Casings; Connections of working fluid for axial pumps
    • F04D29/54—Fluid-guiding means, e.g. diffusers
    • F04D29/541—Specially adapted for elastic fluid pumps
    • F04D29/542—Bladed diffusers
    • F04D29/544—Blade shapes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/70—Shape

Definitions

  • the present invention utilises this knowledge in the eld of high vacuums.
  • the cross-section of the blades is greatly simplified as compared with the cross-section of the blades normally used in turbo-compressors.
  • the problems connected with flows in the viscous and turbulent conditions are no longer encountered in the case of gases in a molecular condition.
  • the various stages of the vacuum pump are simply constituted by a series of thin discs which are alternately fixed and mobile and on the periphery of which the blades are arranged.
  • the present invention relates to a turbo-molecular vacuum pump characterised in that the blades have a triangular cross-section and comprise a sharp edge directed towards the chamber to be evacuated, whilst the opposite face to this edge is directed towards the discharge side.
  • each blade is in the form of truncated prism having a triangular base whose most acute dihedral angle is directed towards the upstream side, i.e. in the direction of the high vacuum. Consequently, the face which is opposite this dihedral angle and whose plane is perpendicular to the axis of rotation of the pump, is turned in the direction of the preliminary vacuum.
  • This arrangement enables the gases diffused from the chamber to be evacuated to penetrate easily into the ducts which are bounded by the blades and which are wide open to these gases.
  • FIG. 1 is an axial sectional View of a turbo-molecular vacuum pump.
  • FIG. 2 is a cross-section on II-II of FIG. 1.
  • FIG. 3 is a partial developed view of two successive blade systems, showing the basic feature of the present invention.
  • the pump shown in FIG. 1 is of a well-known and already old type, having been proposed by Holweck as early as 1922. Suction is effected through the inlet E, in the median plane of the casing C of the pump, the various stages being arranged symmetrically with respect to the median plane, and the outlets S at the two ends of the casing being connected by a pipe T to the suction P of a forepump (not shown) which may be an ordinary vacuum pump.
  • the shaft A of the turbo-molecular pump can be driven by a built-in motor. This shaft is fast with rotary discs R separated by fixed discs F, on the periphery of which discs the blades are arranged.
  • these blades have a triangular cross-sec- 3,138,318 Patented June 23, 1964 "ice tion having a sharp edge a pointing in the direction of the suction side (the direction of flow is designated by the arrow f, whilst the arrow r designates the direction of rotation of the mobile blade system R), so that the ducts delimited by the two neighbouring blades of one and the same disc are wide open to the molecules which are displaced in the direction f and do not encounter, in their travel from the upstream to the downstream sides any arresting transverse surface at any time and whatever the angular position of the rotor.
  • the transverse surfaces s which form the base of the triangles are directed downstream and consequently are impinged against only by the retro-diffusing molecules, which is also advantageous since it must be taken into account that retro-diilusion of gases always takes place whenever there are zones of different molecular density, this retro-diffusion being elfected from the zone of higher molecular density to the zone of lower molecular density.
  • the form and arrangement of the blades thus formed on the periphery of the discs enable the retrodiiusing molecules to be frequently made to strike against the lateral walls of the ducts and also the transverse faces s and to be re-despatched, after temporary absorption, with a component of speed which tends to send them in the downstream direction.
  • the clearances between the fixed blades and the mobile blades should remain small in order that the gases should be always in the molecular condition.
  • a rotary molecular high-vacuum pump of the kind designed to operate in series with and upstream of an ordinary vacuum backing pump comprising a succession of alternately rotary and stationary blade rings, the blades of each of said rings having a cross-section in the form of an obtuse angle triangle with a sharp rectilinear front edge and a planar transverse rear face in a plane substantially perpendicular to the rotation axis, the sharp edges of the blades being circumferentially shifted relative to the corresponding planar faces in the direction of rotation in the case of a rotary blade ring and in the opposite direction in the case of a stationary blade ring, successive rotary and stationary blade rings being mutually arranged so that the sharp edges of one blade ring are immediately adjacent the planar faces of the next preceding blade ring.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Non-Positive Displacement Air Blowers (AREA)

Description

June 23, 1964 H. GARNIER ETAL 3,138,318
TURBO-MOLECULAR vAcuun/L PUMP Filed April 20, 1962 l-NVE/Vks H. L. @ARN/1:@ l.. Rubel A). E MARC/44 L Bv Marsan (1a/1 5ml/le Msou United States Patent O 3,138,318 TURBO-MOLECULAR VACUUM PUMP Henri Louis Garnier, Courbevoie, and Lonide Rubet and Raymond Hippolyte Firmin Marchal, Paris, France, assignors to Societe Nationale dEtude et de Construction de Moteurs dAviation, Paris, France, a company of France Filed Apr. 20, 1962, Ser. No. 189,021 Claims priority, application France May 15, 1961 1 Claim. (Cl. 2310-122) The present invention derives from the principle of the turbo-compressor rotating at a high speed, such as is currently used in aircraft. Experiments, which agree in every way with the theory, have established that a distinctly higher compression rate is obtained when the turbo-compressor operates in a rareiied atmosphere.
The present invention utilises this knowledge in the eld of high vacuums.
In a vacuum pump, the cross-section of the blades is greatly simplified as compared with the cross-section of the blades normally used in turbo-compressors. In fact, the problems connected with flows in the viscous and turbulent conditions are no longer encountered in the case of gases in a molecular condition. The various stages of the vacuum pump are simply constituted by a series of thin discs which are alternately fixed and mobile and on the periphery of which the blades are arranged.
The present invention relates to a turbo-molecular vacuum pump characterised in that the blades have a triangular cross-section and comprise a sharp edge directed towards the chamber to be evacuated, whilst the opposite face to this edge is directed towards the discharge side. In other words, each blade is in the form of truncated prism having a triangular base whose most acute dihedral angle is directed towards the upstream side, i.e. in the direction of the high vacuum. Consequently, the face which is opposite this dihedral angle and whose plane is perpendicular to the axis of rotation of the pump, is turned in the direction of the preliminary vacuum.
This arrangement enables the gases diffused from the chamber to be evacuated to penetrate easily into the ducts which are bounded by the blades and which are wide open to these gases.
The following description with reference to the accompanying drawings, which are given by way of nonlirnitative example, will make it easy to understand how the invention can he carried into effect, the features brought out either from the text or from the drawings being understood to form part of the said invention.
FIG. 1 is an axial sectional View of a turbo-molecular vacuum pump.
FIG. 2 is a cross-section on II-II of FIG. 1.
FIG. 3 is a partial developed view of two successive blade systems, showing the basic feature of the present invention.
The pump shown in FIG. 1 is of a well-known and already old type, having been proposed by Holweck as early as 1922. Suction is effected through the inlet E, in the median plane of the casing C of the pump, the various stages being arranged symmetrically with respect to the median plane, and the outlets S at the two ends of the casing being connected by a pipe T to the suction P of a forepump (not shown) which may be an ordinary vacuum pump. The shaft A of the turbo-molecular pump can be driven by a built-in motor. This shaft is fast with rotary discs R separated by fixed discs F, on the periphery of which discs the blades are arranged.
According to the present invention, and as FIG. 3 shows clearly, these blades have a triangular cross-sec- 3,138,318 Patented June 23, 1964 "ice tion having a sharp edge a pointing in the direction of the suction side (the direction of flow is designated by the arrow f, whilst the arrow r designates the direction of rotation of the mobile blade system R), so that the ducts delimited by the two neighbouring blades of one and the same disc are wide open to the molecules which are displaced in the direction f and do not encounter, in their travel from the upstream to the downstream sides any arresting transverse surface at any time and whatever the angular position of the rotor.
Indeed, the transverse surfaces s which form the base of the triangles are directed downstream and consequently are impinged against only by the retro-diffusing molecules, which is also advantageous since it must be taken into account that retro-diilusion of gases always takes place whenever there are zones of different molecular density, this retro-diffusion being elfected from the zone of higher molecular density to the zone of lower molecular density.
Furthermore, in order to promote the carrying of the molecules towards the downstream blades, it is convenient to incline the axis of the ducts of one and the same fixed or mobile disc in the desired direction in accordance with the direction of rotation of the pump.
In fact, the form and arrangement of the blades thus formed on the periphery of the discs enable the retrodiiusing molecules to be frequently made to strike against the lateral walls of the ducts and also the transverse faces s and to be re-despatched, after temporary absorption, with a component of speed which tends to send them in the downstream direction.
In this way, retro-diffusion is reduced and the output and the compression rate of the pump are increased.
The clearances between the fixed blades and the mobile blades should remain small in order that the gases should be always in the molecular condition.
What is claimed is:
A rotary molecular high-vacuum pump of the kind designed to operate in series with and upstream of an ordinary vacuum backing pump, comprising a succession of alternately rotary and stationary blade rings, the blades of each of said rings having a cross-section in the form of an obtuse angle triangle with a sharp rectilinear front edge and a planar transverse rear face in a plane substantially perpendicular to the rotation axis, the sharp edges of the blades being circumferentially shifted relative to the corresponding planar faces in the direction of rotation in the case of a rotary blade ring and in the opposite direction in the case of a stationary blade ring, successive rotary and stationary blade rings being mutually arranged so that the sharp edges of one blade ring are immediately adjacent the planar faces of the next preceding blade ring.
References Cited in the le of this patent UNITED STATES PATENTS 621,030 Case et al. Mar. 14, 1899 647,856 Marburg Apr. 17, 1900 853,363 Holzwarth May 14, 1907 1,529,925 Say Mar. 17, 1925 2,435,236 Redding Feb. 3, 1948 2,579,049 Price Dec. 18, 1951 2,738,950 Price Mar. 20, 1956 2,974,927 Johnson Mar. 14, 1961 FOREIGN PATENTS 626,780 Great Britain July 21, 1949 682,418 Great Britain Nov. 12, 1952 418,198 France Sept. 21, 1910
US189021A 1961-05-15 1962-04-20 Turbo-molecular vacuum pump Expired - Lifetime US3138318A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3644051A (en) * 1969-10-27 1972-02-22 Sargent Welch Scientific Co Turbomolecular and stator pump having improved rotor construction
US4732530A (en) * 1984-07-25 1988-03-22 Hitachi, Ltd. Turbomolecular pump
US5358373A (en) * 1992-04-29 1994-10-25 Varian Associates, Inc. High performance turbomolecular vacuum pumps
US6261052B1 (en) * 1999-01-08 2001-07-17 Fantom Technologies Inc. Prandtl layer turbine
US20040091351A1 (en) * 2000-09-20 2004-05-13 Ralf Adamietz Turbomolecular vacuum pump with rows of rotor blades and rows of stator blades

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US621030A (en) * 1899-03-14 Pressure-blower
US647856A (en) * 1899-04-26 1900-04-17 Franz Marburg Jr Rotary pump or the like.
US853363A (en) * 1905-05-26 1907-05-14 Hooven Owen Rentschler Company Turbo-blower.
FR418198A (en) * 1910-07-13 1910-12-02 Paul Turlur Paul Turlur Fin with broken outlet surface for ventilator Fin with broken outlet surface for fans, centrifugal pumps, turbines or other apparatus, centrifugal pumps, turbines or other similar apparatus
US1529925A (en) * 1922-06-19 1925-03-17 Say James Turbo blower
US2435236A (en) * 1943-11-23 1948-02-03 Westinghouse Electric Corp Superacoustic compressor
GB626780A (en) * 1947-04-25 1949-07-21 Alan Arnold Griffith Improvements relating to aerofoils and aerofoil blading
US2579049A (en) * 1949-02-04 1951-12-18 Nathan C Price Rotating combustion products generator and turbine of the continuous combustion type
GB682418A (en) * 1949-05-24 1952-11-12 Onera (Off Nat Aerospatiale) Improvements in shock wave compressors, in particular for aircraft continuous flow engines
US2738950A (en) * 1945-12-13 1956-03-20 Lockheed Aircraft Corp Turbine machine having high velocity blading
US2974927A (en) * 1955-09-27 1961-03-14 Elmer G Johnson Supersonic fluid machine

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US621030A (en) * 1899-03-14 Pressure-blower
US647856A (en) * 1899-04-26 1900-04-17 Franz Marburg Jr Rotary pump or the like.
US853363A (en) * 1905-05-26 1907-05-14 Hooven Owen Rentschler Company Turbo-blower.
FR418198A (en) * 1910-07-13 1910-12-02 Paul Turlur Paul Turlur Fin with broken outlet surface for ventilator Fin with broken outlet surface for fans, centrifugal pumps, turbines or other apparatus, centrifugal pumps, turbines or other similar apparatus
US1529925A (en) * 1922-06-19 1925-03-17 Say James Turbo blower
US2435236A (en) * 1943-11-23 1948-02-03 Westinghouse Electric Corp Superacoustic compressor
US2738950A (en) * 1945-12-13 1956-03-20 Lockheed Aircraft Corp Turbine machine having high velocity blading
GB626780A (en) * 1947-04-25 1949-07-21 Alan Arnold Griffith Improvements relating to aerofoils and aerofoil blading
US2579049A (en) * 1949-02-04 1951-12-18 Nathan C Price Rotating combustion products generator and turbine of the continuous combustion type
GB682418A (en) * 1949-05-24 1952-11-12 Onera (Off Nat Aerospatiale) Improvements in shock wave compressors, in particular for aircraft continuous flow engines
US2974927A (en) * 1955-09-27 1961-03-14 Elmer G Johnson Supersonic fluid machine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3644051A (en) * 1969-10-27 1972-02-22 Sargent Welch Scientific Co Turbomolecular and stator pump having improved rotor construction
US4732530A (en) * 1984-07-25 1988-03-22 Hitachi, Ltd. Turbomolecular pump
US5358373A (en) * 1992-04-29 1994-10-25 Varian Associates, Inc. High performance turbomolecular vacuum pumps
US6261052B1 (en) * 1999-01-08 2001-07-17 Fantom Technologies Inc. Prandtl layer turbine
US20040091351A1 (en) * 2000-09-20 2004-05-13 Ralf Adamietz Turbomolecular vacuum pump with rows of rotor blades and rows of stator blades

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