US3302864A - Oil-vapor diffusion vacuum pump - Google Patents

Oil-vapor diffusion vacuum pump Download PDF

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Publication number
US3302864A
US3302864A US409265A US40926564A US3302864A US 3302864 A US3302864 A US 3302864A US 409265 A US409265 A US 409265A US 40926564 A US40926564 A US 40926564A US 3302864 A US3302864 A US 3302864A
Authority
US
United States
Prior art keywords
boiler
working fluid
vapor
oil
ejector
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US409265A
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English (en)
Inventor
Nicolas Michel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INDUSTRIELLE FRANCAISE DES TUBES ELECTRONIQUES Cie
Original Assignee
INDUSTRIELLE FRANCAISE DES TUBES ELECTRONIQUES Cie
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
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Application granted granted Critical
Publication of US3302864A publication Critical patent/US3302864A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F9/00—Diffusion pumps
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/4456—With liquid valves or liquid trap seals
    • Y10T137/4643—Liquid valves
    • Y10T137/4666—With baffle

Definitions

  • This invention relates to improvements in sea-l devices for use in vacuum pumps, operating according to the oilvapor diffusion principle, .to permit return to the boiler of the oil .condensed in the pump body while preventing any flow in the opposite direction of oil vapor generated in the boiler.
  • the vapor according to the conventional principle of operation of these vacuum pumps, will necessarily flow through the intermediate member or ejector from which this vapor is caused to diffuse into the pump body before condensing on the cooled wall of said body.
  • Such automatic units may comprise a relatively high number of working positions or stations (for example 16, 24, 30, 36 or more), each position or station having its diffusion pump, this requirement being of primary interest for combining highquality products with high pumping rates.
  • the seal thus obtained in the form of a single ring of liquid oil cannot be effective unless this ring is of relatively great height or thickness, for example of the order of one inch.
  • this dimension is acceptable in the case of relatively large diffusion pumps not limited by maximum over-all dimensions, it cannot be contemplated in the case of pumps to be mounted on automatic pumping units due to the essential requirements set forth hereinabove.
  • the magnitude of the total area of the registering metal surfaces on either side of the oil ring implies, for the ejector, a loss of heat which is proportional to said area. This loss of heat occurs as a matter of fact through the hot oil towards the cooled pump body.
  • Another feature characterizing this invention is that it permits reducing not only the heightof the ring of condensed oil but also the surface area of the ejector and pump bodies.
  • the height of the oil ring is reduced by splitting the ring into at least two rings or sub-rings, and the surface area is reduced by forming the ejector body with a splined or castellated section by machining at least three collars regularly spaced in the axial direction, these collars having different diameters so as to leave gradually increasing gaps between themselves and the inner wall of the pump body, two adjacent collars forming therebetween an annular cavity.
  • the device considered as a whole has at least two such annular cavities wherein the oil condensing along the pump body flows towards the boiler to constitute a seal in the form of said liquid rings or sub-rings.
  • the relative spacing of said collars is determined by the trial and error method so that between two adjacent collars or rings (with due consideration for the volumes occupied by these rings) there is an oil-free space, the above-defined annular cavities thus forming behind said rings what may be termed expansion chambers, whereby, throughout the height of the zone bounded by said rings, a pressure gradient is created which, in conjunction with the temperature drop produced at this levelas a I consequence of the presence of condensed oil, causes any oil vapor molecule tending to escape from the boiler along the pump body and the ejector body to be compulsori-ly condensed at least in the second cavity (as proved experimentally by observing the phenomenon in a pump provided with the deviceconstituting the subject-matter of this invention but having a glass and therefore transparent body) so that the assembly actually corresponds to the desired sealing device, the provision of a third cavity (by machining a fourth collar on the ejector body) being merely an additional safety measure; therefore, the fourth collar or ring is considered
  • the geometrical shape of the device taken as a whole is subordinate to the quantity of oil utilized.
  • the dimensions of the gaps left between each collar and the inner wall of the pump body are respectively 0.03" in the case of the fourth and third rings or collars, 0.02" in the case of the second collar, and 0.012" in the case of the first collar, the height of the zone covered by these four collars being A and, corresponding to a relative spacing of 0.20 between adjacent rings or'collars and a thickness of 0.04" for each collar, these dimensions being given by way of example, of course, without'limiting in any way the present invention.
  • the device of this invention which is easy to manufacture and maintain, is characterized by the following advantageous features:
  • FIG. 1 is a longitudinal or axial section showing a pump assembly equipped with the device constituting the subject-matter of this invention
  • FIG. 2 is another axial sectional view showing on a larger scale the pump portion constituting the aforesaid device.
  • FIG. 3 is a fragmentary enlarged View of the pump portion of FIG. 2 provided with a seal device according to the invention and illustrates the formation Of th $63 by the seal device.
  • Thepump body 1 with its cooling jacket 2 carries at its lower portion a boiler 3 and at its upper portion a flange 4 for connecting the pump to a pipe, duct or enclosure to be vacuumized and not shown.
  • a nozzle 5 permits connecting the pump to a primary pump (not shown) for priming and maintaining the preliminary vacuum.
  • An ejector 6 (with its steam deflection cones or jet means such as 7 and 8) is centered on a bottom plate 9 of the boiler 3 by means of a simple central rod arrangement 10 ermitting a convenient assembling and disassembling for maintenance purposes.
  • a heating element 11 (consisting for example of a shielded resistance of adequate configuration contacting the outer surface of boiler plate 9 by means of a fiat face increasing considerably the heat transfer from said heating element and the boiler), and a protective case 12 are both secured to theboiler by means of a screw-threaded rod 13.
  • a set of collars or rings 14 machined on the outer surface of the ejector provides in conjunction with the pump body and the ejector body three annular cavities constituting as many expansion chambers C C and C
  • the configuration of these rings or collars is shown more in detail in FIGS. 2 and 3 together with the dimension of the corresponding radial annuli or gaps d, c, b, a, formed between each collar and the inner wall of the pump body.
  • the actual values of these gaps, which, de crease towards the boiler have already been given hereinabove by way of example in the case of a specific oil grade used by the applicant, namely silicone fluids Si 703 and 704.
  • a drip rib 15 is provided at the lower end of the pump body, around the aperture thereof opening into the boiler, whereby the condensed oil will return to the boiler from this rib, that is, from the pump body, instead of from the lowermost ring of the ejector, thus avoiding, as already set forth hereinabove, the cooling of the ejector by re,- evaporation of oil in this zone and therefore further increasing the thermal efficiency of the assembly.
  • the factthat. the. ejector, due to its specific mounting, is completely independent of the pump body (as contrasted with pumps of relatively moderate overall dimensions of prior art arrangements) further improves the thermal efficiency of the assembly.
  • the pumps thus equipped are characterlzed by an improvement of the limit vacuum, this improvement being apparently ascribab-le to a kind of fractional distillation adapted to promote the separation of the gaseous molecules included in the oil used in the pump.
  • An alternate form of embodiment of this invention consists in forming the annuli on the inner wall of the pump body instead of on the outer wall of the ejector body which in this case is smooth, the same relative spacings and gaps being provided between the corresponding portions of said annuli registering with the outer wall of the ejector; however, to simplify the machining operations the preferred disposal is that described hereinabove and shown in the attached drawings.
  • the device of this invention while developed and applied herein to pumps of moderate size and therefore of moderate capacity is also applicable to largecapacity pumps.
  • an ejector comprising an inner tubular element mounted in communication with said boner for receiving vapor of the working fluid and means defining vapor jet means for developing a vacuum with said ejector in operation, an outer wall circumferentially of said inner tube extending axially of said inner tube and spaced outwardly therefrom defining an annular space in communication with said boiler for returning condensed vapor of said working fluid to said boiler, the improvement which comprises seal means in said space to preclude working fluid in a vapor phase from said boiler entering said annular space and allowing working fluid in a condensed state to return to said boiler, said seal means comprising a plurality of collars disposed axially spaced in said tubular space extending inwardly defining in said space annular gaps of different dimensions between the inner tube and said outer peripheral wall effective to entrap condensed working fluid in a liquid phase to form respective seal rings of liquid working fluid at each of said gaps,

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Jet Pumps And Other Pumps (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US409265A 1963-11-08 1964-11-05 Oil-vapor diffusion vacuum pump Expired - Lifetime US3302864A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR953126A FR1382330A (fr) 1963-11-08 1963-11-08 Perfectionnement aux pompes à diffusion à vapeur d'huile

Publications (1)

Publication Number Publication Date
US3302864A true US3302864A (en) 1967-02-07

Family

ID=8816117

Family Applications (1)

Application Number Title Priority Date Filing Date
US409265A Expired - Lifetime US3302864A (en) 1963-11-08 1964-11-05 Oil-vapor diffusion vacuum pump

Country Status (5)

Country Link
US (1) US3302864A (de)
DE (1) DE1428289A1 (de)
FR (1) FR1382330A (de)
GB (1) GB1023628A (de)
NL (1) NL6412783A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3362622A (en) * 1966-07-13 1968-01-09 Nat Res Corp Diffusion pump
US3362623A (en) * 1966-08-23 1968-01-09 Nat Res Corp Oil diffusion pump with splash boiler
US3437261A (en) * 1966-04-05 1969-04-08 Leybold Heraeus Gmbh & Co Kg Diffusion pump
WO1979000957A1 (en) * 1978-04-21 1979-11-15 Varian Associates Electric heater assembly for diffusion pumps
US4270067A (en) * 1977-10-18 1981-05-26 Trans-Canada Life-Ware Limited Electric frying pan
EP0791752A2 (de) * 1996-02-19 1997-08-27 The BOC Group plc Diffusionspumpe

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2074749A1 (en) * 1970-01-23 1971-10-08 Merlin Gerin Vacuum diffusion pump body - and process for casting it
US4373868A (en) * 1976-07-06 1983-02-15 Varian Associates, Inc. Diffusion pump for leak detector
US5137429A (en) * 1991-04-15 1992-08-11 Spectrameasure Inc. Diffusion pump

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB475062A (en) * 1936-05-12 1937-11-12 Godfrey Burrows Improvements in vapour condensation or diffusion pumps
US2404022A (en) * 1945-04-21 1946-07-16 Alexander Paul Vapor vacuum pump of the double jet type
US2585139A (en) * 1950-10-10 1952-02-12 Nat Res Corp High-vacuum pump
DE1032470B (de) * 1956-04-09 1958-06-19 Tesla Np OEldiffusionspumpe

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB475062A (en) * 1936-05-12 1937-11-12 Godfrey Burrows Improvements in vapour condensation or diffusion pumps
US2404022A (en) * 1945-04-21 1946-07-16 Alexander Paul Vapor vacuum pump of the double jet type
US2585139A (en) * 1950-10-10 1952-02-12 Nat Res Corp High-vacuum pump
DE1032470B (de) * 1956-04-09 1958-06-19 Tesla Np OEldiffusionspumpe

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3437261A (en) * 1966-04-05 1969-04-08 Leybold Heraeus Gmbh & Co Kg Diffusion pump
US3362622A (en) * 1966-07-13 1968-01-09 Nat Res Corp Diffusion pump
US3362623A (en) * 1966-08-23 1968-01-09 Nat Res Corp Oil diffusion pump with splash boiler
US4270067A (en) * 1977-10-18 1981-05-26 Trans-Canada Life-Ware Limited Electric frying pan
WO1979000957A1 (en) * 1978-04-21 1979-11-15 Varian Associates Electric heater assembly for diffusion pumps
US4251713A (en) * 1978-04-21 1981-02-17 Varian Associates, Inc. Electric heater assembly for diffusion pumps
EP0791752A2 (de) * 1996-02-19 1997-08-27 The BOC Group plc Diffusionspumpe
EP0791752A3 (de) * 1996-02-19 1998-06-17 The BOC Group plc Diffusionspumpe
US5913662A (en) * 1996-02-19 1999-06-22 The Boc Group Plc Diffusion pump with two inlets and two stage pumping capability

Also Published As

Publication number Publication date
DE1428289A1 (de) 1969-12-18
GB1023628A (en) 1966-03-23
FR1382330A (fr) 1964-12-18
NL6412783A (de) 1965-05-10

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