US3902330A - Vacuum pump - Google Patents

Vacuum pump Download PDF

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Publication number
US3902330A
US3902330A US449551A US44955174A US3902330A US 3902330 A US3902330 A US 3902330A US 449551 A US449551 A US 449551A US 44955174 A US44955174 A US 44955174A US 3902330 A US3902330 A US 3902330A
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US
United States
Prior art keywords
housing
trap
vacuum pump
vapour
support
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
US449551A
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English (en)
Inventor
Basil Dixon Power
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.)
BOC Group Ltd
Original Assignee
British Oxigen Ltd
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 British Oxigen Ltd filed Critical British Oxigen Ltd
Application granted granted Critical
Publication of US3902330A publication Critical patent/US3902330A/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
    • F04F9/06—Arrangement of vapour traps

Definitions

  • VACUUM PUMP This invention relates to a vacuum pump, and particularly to a vapour vacuum pump.
  • the present invention aims at improving the vapourtrapping efficiency by including a refrigerated trap so that incident vapour molecules become condensed or frozen on the trapping surfaces.
  • FIG. 1 is a side view, part in section and part in elevation, of one form of vapour vaccuum pump of the present invention.
  • FIG. 2 is a fragmentary view of part of the pump shown in FIG. 1, with an alternative form of heat sink.
  • the housing 2 of the vapour vacuum pump of the present invention is belled-out in the region of the upper nozzle 42 of the vapour jet assembly. This leaves a gas flow passage of sufficiently-large cross-sectional area between the adjacent part of the housing 2 and the water-cooled baffle member 10, of which most is positioned above the vapour jet assembly but which includes a water-cooled skirt 54 extending below the upper vapour nozzle 42 to function as a cold cap.
  • the belled-out portion of the housing has a cylindrical part 70 which is cooled by means of wrapped tubes 8 through which is passed a flow of cold water.
  • An annular seat or flange 72 is secured to the outer surface of the cylindrical wall 70 in a vacuum-tight manner. such as by being welded or brazed thereto.
  • the seat 72 defines a cylindrical opening into the interior of housing 2,'and also provides a substantially planar, annular seat for a thermal stand off member 74 which is able to be secured to seat 72 by several screws 76.
  • the stand-off member 74 is preferably of stainless steel or like material having a low thermal conductivity and yet sufficient mechanical strength to support a heat sink member 78 intended to be inserted into the interior of housing 2.
  • the gap between member 74 and insert 78 is evacuated when the pump is in use, so that the insert 78 is vacuum insulated thermally from housing 2.
  • the insert 78 is adapted to be refrigerated to a suita bly-low temperature by any convenient means.
  • the means shown in the drawing, but only be way of example, is to mount on the outer end of insert 78 a device 80 which is adapted to cool the outer end of the insert by using the Peltier effect, which is a phenomenon whereby heat is liberated or absorbed at ajunction between dissimilar metals when electric current is passed across the junction.
  • the current is introduced to device 80 by electrical leads (not shown) and insert 78 is in thermal contact with that junction which absorbs heat when current is passed through it.
  • the junction which liberates heat is cooled as by water or air introduced through conduits 82.
  • the rate of absorption of heat by the cold junction is designed to be sufficiently great for the trapping surfaces (to be described below in greater detail) to be cooled to a sufficientlylow temperature below that which the water-cooled baffles reach in use.
  • FIG. 2 shows in greater detail than in FIG. 1 an alternative form of Peltier-effect device, Parts already shown in FIG. 1 have been given the same references.
  • the seat 72 has secured directly to it a housing 96 containing a Peltier-effect element 98 having its hot junction in contact with a wall 100, and its cold junction in contact with the outer end of heat sink member 78.
  • the electrical conductors to element 98 have been omitted from the drawing for clarity. Mechanical compression forces on the contacting surfaces are applied by a strained frusto'conical spring 102.
  • the wall 100 is cooled by water introduced and exhausted through conduits 82.
  • the heat sink 78 is supported by a stand-off 74 which is introverted compared with that shown in FIG. I.
  • the hollow cylindrical space between stand-off 74 and heat sink 78 is preferably filled with a thermal insulant, such as cellulosic fibres. This is to insulate the heat sink 78 thermally from the water-cooled casing 2 of the pump, which casing is relatively warm compared with the temperature attained by heat sink 78 in use.
  • cooling of the insert 78 can be achieved by any other convenient means.
  • the outer end of a modified insert could be arranged to dip into a body of liquid nitrogen or other cryogenic liquid; it could be provided with internal passages along which could flow a suitable refrigerant liquid, such as that sold under the trade mark FREON, or the insert 78 could take the form of a thermodynamic engine adapted to remove heat.
  • the characterising feature of the present invention is that the refrigerated trap is in the form of at least two separable portions.
  • the insert 78 functions as the main part of one portion, while the other portion 84 provides the trapping surfaces themselves.
  • Portion 84 comprises basically a dish 86 supporting an array of three frusto-conical members 88, these members being supported by means of stands 90 having slots into which the members 88 fit, the stands 90 being intended to be positioned on the base of dish 86.
  • the stands 90 (of which only one is shown) are in good thermal contact with both the members 88 and the dish 86, being normally secured thereto by being soldered or brazed.
  • the dish 86 and the members 88 have the distinguishing characteristic that they are each able to be passed through the part of the isolation valve 12 when the valve plate 64 of the valve is removed therefrom.
  • the dish 86 and members 88 cooperate to form an optical trap which prevents there being a line-of-sight from the interior of the upper part of the vapour pump housing to any part of the isolation valve 12 or adjacent surface. Because vapour molecules tend to travel in straight lines for long distances under the high vacuum attained in the interior of the vapour pump housing.
  • the optical trap criterion ensures that no such vapour molecule is able to impinge directly on an unrefrigerated surface upstream of the trap, and the degree of cooling of the dish 86 and members 88 is such that vapour molecules incident on the dish or members become condensed or frozen thereto and are not able to impinge subsequently on any warmer surface from which the molecules might be reevaporated and enter the equipment being evacuated.
  • the mounting assembly is reversed. First the isolation valve 12 has the valve plate 64 removed and then the screws 94 are unscrewed until all the trapping surfaces can be removed as a unit through the opening so formed, together with the strip 92 and screw 94. When this has been done the screws 76 can be removed to permit insert 78 to be withdrawn from the interior of the housing 2, for repair or replacement, but mainly to give access to pump components lower down inside the pump housing 2. It will be noted that all these components are dimensioned so as to enable them to be withdrawn through the port of the isolation valve.
  • the present invention provides an improved vapour vacuum pump in which the vapour-trapping efficiency is increased by providing refrigerated surfaces so arranged that there is a high probability that any vapour molecules migrating towards the pump mouth will collide with them and thereby become immobilised.
  • a vapour vacuum pump having a housing internally of which there is a water-cooled baffle and a vapourjet assembly; a trap positioned in the gas flow path upstream of the baffle, and adapted to be cooled, the trap being in two separate portions, of which one portion is insertable through the wall of the housing. and is able to be secured thereto.
  • the said one portion having heat extraction means so that it acts as a heat sink, and of which the other portion functions as a trap, being insertable through the top of the housing and being able to be connected thermally to the said heat sink portion, said heat extraction means including a mechanical support for the said trap portion within the housing. the support extending through the housing wall to the exterior thereof and carrying means for cooling on its outer end outward of the housing for cooling the support to a temperature substantially below room temperature.
  • a vapour vacuum pump as claimed in claim I in which the said cooling means utilises a Peltier-effect device.
  • a vapour vacuum pump having a housing internally of which there is a water-cooled baffle and a vapourjet assembly; a trap positioned in the gas flow path upstream of the baffle, and adapted to be cooled, the trap being in two separate portions, of which one portion is insertable through the wall of the housing, and is able to be secured thereto, the said one portion having heat extraction means so that it acts as a heat sink. and of which the other portion functions as a trap, being insertable through the top of the housing and being able to be connected thermally to the said heat sink portion.
  • said heat extraction means including a mechanical support for the said trap portion, the support also carrying means for cooling its outer end to a temperature substantially below room temperature, the support being mechanically secured to the pump housing by means of a thermal stand-off.
  • thermo stand-off takes the form of a thinwalled tube extending in parallel with and spaced radially from, the support, the tube being connected at one end to the support in a vacuum-tight manner. and at the other end to a member adapted to be detachably connected to the pump housing.
  • a vapour vacuum pump having a housing internally of which there is a water-cooled baffle and a vapourjet assembly; a trap positioned in the gas flow path upstream of the baffle, and adapted to be cooled, the trap being in two separate portions, of which one portion is insertable through the Wall of the housing, and is able to be secured thereto.
  • the said one portion having heat extraction means so that it acts a heat sink, and of which the other portion functions as a trap, being insertable through the top of the housing and being able to be connected thermally to the said heat sink portion, said trap portion taking the form of a dish adapted to be detachably connected to the said one portion and to support an array of vertically-spaced trapping members in thermal contact with the dish.
  • each trapping member is in the form of a frustoconical member, the dish and the trapping members cooperating to form an optical trap.
  • a vapour vacuum pump as claimed in claim 9 in which the dish. the slotted stands and the trapping members are firmly secured to each other by brazing material.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US449551A 1973-03-08 1974-03-08 Vacuum pump Expired - Lifetime US3902330A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1133473A GB1448752A (en) 1973-03-08 1973-03-08 Vacuum pumping assembly

Publications (1)

Publication Number Publication Date
US3902330A true US3902330A (en) 1975-09-02

Family

ID=9984343

Family Applications (1)

Application Number Title Priority Date Filing Date
US449551A Expired - Lifetime US3902330A (en) 1973-03-08 1974-03-08 Vacuum pump

Country Status (6)

Country Link
US (1) US3902330A (enrdf_load_stackoverflow)
JP (1) JPS5047210A (enrdf_load_stackoverflow)
DE (1) DE2410672A1 (enrdf_load_stackoverflow)
FR (1) FR2220691B1 (enrdf_load_stackoverflow)
GB (1) GB1448752A (enrdf_load_stackoverflow)
IT (1) IT1007414B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4718251A (en) * 1986-03-24 1988-01-12 British Aerospace De-contaminated fluid supply apparatus and cryogenic cooling systems using such apparatus
US5548964A (en) * 1993-07-29 1996-08-27 Applied Materials, Inc. Method and apparatus for cooling a vacuum device

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2233879A5 (enrdf_load_stackoverflow) * 1973-06-15 1975-01-10 British Oxygen Co Ltd
GB9504260D0 (en) * 1995-03-03 1995-04-19 Boc Group Plc Improvements in diffusion pumps
US7194861B2 (en) 2004-11-26 2007-03-27 Bishop Lloyd E Two stroke steam-to-vacuum engine

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2934257A (en) * 1956-01-25 1960-04-26 Edwards High Vacuum Ltd Vapour vacuum pumps
US3122896A (en) * 1962-10-31 1964-03-03 Cryovac Inc Pump heat radiation shield
US3423947A (en) * 1967-07-17 1969-01-28 Yosimaro Moriya Vacuum traps utilizing electronic refrigerating elements
US3579998A (en) * 1968-08-01 1971-05-25 Air Liquide Cryogenic pumping device for the creation of very high vacua
US3635039A (en) * 1969-04-28 1972-01-18 British Oxygen Co Ltd Vapor traps
US3719052A (en) * 1971-05-04 1973-03-06 G White Vacuum system cold trap
US3785162A (en) * 1971-12-07 1974-01-15 Cit Alcatel Diffusion pump assembly

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1066971A (en) * 1963-05-30 1967-04-26 Edwards High Vacuum Int Ltd Improvements in or relating to vacuum pumps

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2934257A (en) * 1956-01-25 1960-04-26 Edwards High Vacuum Ltd Vapour vacuum pumps
US3122896A (en) * 1962-10-31 1964-03-03 Cryovac Inc Pump heat radiation shield
US3423947A (en) * 1967-07-17 1969-01-28 Yosimaro Moriya Vacuum traps utilizing electronic refrigerating elements
US3579998A (en) * 1968-08-01 1971-05-25 Air Liquide Cryogenic pumping device for the creation of very high vacua
US3635039A (en) * 1969-04-28 1972-01-18 British Oxygen Co Ltd Vapor traps
US3719052A (en) * 1971-05-04 1973-03-06 G White Vacuum system cold trap
US3785162A (en) * 1971-12-07 1974-01-15 Cit Alcatel Diffusion pump assembly

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4718251A (en) * 1986-03-24 1988-01-12 British Aerospace De-contaminated fluid supply apparatus and cryogenic cooling systems using such apparatus
US5548964A (en) * 1993-07-29 1996-08-27 Applied Materials, Inc. Method and apparatus for cooling a vacuum device

Also Published As

Publication number Publication date
JPS5047210A (enrdf_load_stackoverflow) 1975-04-26
IT1007414B (it) 1976-10-30
FR2220691A1 (enrdf_load_stackoverflow) 1974-10-04
DE2410672A1 (de) 1974-09-12
FR2220691B1 (enrdf_load_stackoverflow) 1978-02-10
GB1448752A (en) 1976-09-08

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