US3782861A - Oil diffusion vacuum pump - Google Patents

Oil diffusion vacuum pump Download PDF

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Publication number
US3782861A
US3782861A US00305938A US3782861DA US3782861A US 3782861 A US3782861 A US 3782861A US 00305938 A US00305938 A US 00305938A US 3782861D A US3782861D A US 3782861DA US 3782861 A US3782861 A US 3782861A
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United States
Prior art keywords
envelope
projections
oil
heating element
chimneys
Prior art date
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Expired - Lifetime
Application number
US00305938A
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English (en)
Inventor
T Abe
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.)
Ayumi Industry Co Ltd
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Ayumi Industry Co Ltd
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Publication date
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    • 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

Definitions

  • An diffusion pump has a of ceaxi- [5 arranged cylindrical chimneys; extending from the [58] F wk!
  • OIL DIFFUSION VACUUM PUMP This invention relates to an improved oil diffusion vacuum pump and more particularly to a diffusion pump of the fractional distillation type.
  • a conventional oil diffusion pump of this type comprises a cylindrical envelope having a flat bottom and a plurality of cylindrical distillation towers standing erect and coaxially in the envelope.
  • the upper portion of the casing is referred to as a condenser and is provided with a cooling water pipe wound thereon and the lower portion thereof is referred to as a boiler and is provided with an electric heating element attached to the bottom.
  • the boiler contains an appropriate quantity of diffusion pump oil having a lower vapor pressure.
  • an object of this invention is to provide an improved oil diffusion pump of fractional distillation type which overcomes the foregoing disadvantages by providing its boiler with a novel and improved structure which can substantially avoid a temperature difference in the oil as mentioned above.
  • the bottom of the boiler has a plurality of annular upwardly extending hollow projections arranged concentrically so as to be located respectively between the respective distillation towers, and the heating element of the boiler has a plurality of annular projections arranged concentrically to fit in the annular grooves of the hollow projections of the boiler.
  • FIG. 1 is a schematic cross-sectional view of a prior art oil diffusion pump of fractional distillation type
  • FIG. 2 is a schematic cross-sectional side view of an embodiment of an oil diffusion pump according to this invention.
  • FIG. 3 is a fragmentary cross-sectional side view of the boiler of the diffusion pump of FIG. 2;
  • FIG. 4 is a bottom view of the boiler of FIG. 3;
  • FIG. 5 is a perspective view of an embodiment of the heating element for use with the boiler of FIGS. 3 and 4;
  • FIGS. 6, 7 and 8 are diagrams illustrating the test results and the improved characteristics of the diffusion pump of this invention.
  • the prior art diffusion pump includes a cylindrical envelope 1 which may be made of glass or metal, the lower portion 2 of which the so called boiler has a flat bottom 3 which is preferably made of metal and hermetically sealed to the envelope 1.
  • the upper end of the envelope 1 is provided with a hermetically sealed metal flange 4 for coupling the pump to a chamber and constitutes an inlet port 7.
  • the cylindrical envelope 1 has a branch pipe 5 having at hermetically sealed metal flange 6 at the end which is to be coupled to a fore-pump, such as mechanical rotary vacuum pump, to constitute an output port 8.
  • chimneys In the envelope 1, three coaxial upright metal cylinders 9, l0 and I] referred to as chimneys have heights which are highest in the center and successively decrease toward the outside.
  • the chimneys 9, l0 and 11 have umbrellas 12, 13 and 14 respectively supported above them to form nozzles 15, 16 and 17 respectively therebetween.
  • holes 18, 19 and 20 are formed in diametrical alignment and on alternate sides.
  • An appropriate quantity of diffusion pump oil 21 is contained in the boiler 2.
  • a heating element 22 is positioned in intimate contact therewith.
  • the heating element 22 is made of a material having high heat conductivity, such as metal, and includes an electric heater 23 which is electrically insulated and embedded in the material.
  • a helical cooling water pipe 24 is wound on the upper portion of envelope 1 and is hereinafter referred to as a condenser.
  • the oil 21 is heated by the heating element 22 to evaporate it and the vapor flows upwardly in the distillation towers or chimneys 9, 10 and I1 and then outwardly and downwardly through nozzles I5, 16 and 17. Therefore, the gas in the envelope 1 moves downwardly with the oil vapor and is exhausted from the outlet 8 but the oil vapor cooled and condensed by the cooling pipe 24 falls into the boiler 21. During this circulation the oil 21 moves from the outside into the center passing through the holes 20, 19 and 18 and around the feet of the chimneys ll, 10 and 9 successively.
  • the bottom 3 of the boiler 2 is provided with upward hollow projections 25, 26 and 27 which are recessed from the underside. While the projection 25 is cylindrical and stands in the center of the chimney 9, the other projections 26 and 27 each have a circular' shape with a narrow portion omitted to form a gap 31 as shown in FIGS. 3 and 4 and are positioned between the chimneys 9 and 10 and 10 and 11 respectively.
  • the diffusion pump oil 21 is at a level approximately midway of the height of the projections.
  • the holes 18, 19 and 20 of the chimneys 9, 10 and 11 are formed in the same side along a radius extending in a direction opposite to the gaps 31 of the projections 26 and 27 so that the oil 21 flows excursively between the chimneys and the projections from the outside to the center as readily understood.
  • the recesses of the projections 25, 26 and 27 receive projections 28, 29 and 30 respectively which are formed integrally with the heating element 22 and shaped similarly to the projections 25, 26 and 27 so that intimate contact is established between the inner walls of the underside recesses of the projections 25, 26 and 27 and the surfaces of the projections 28, 29 and 30 as shown in further detail in FIG. 5.
  • the gap 34 corresponds to the gap 31 in FIG. 4 and numerals 32 and 33 represent terminals of the heater 23 which is insulated from and embedded in the body of the heating element 22.
  • the projections 28, 29 and 30 of the heating element 22 are preferably made of the same material as the body of the element which has a high heat conductivity.
  • the temperature difference between the surface and bottom of the oil 21 is very small and disturbance and bumping of the oil disappears completely. Moreover, decomposition of the oil due to excessive heating is prevented. Thus, the exhausting ability of the diffusion pump has been remarkably improved as will be described.
  • FIG. 6 shows the variation of the exhaust speed in percentage with reference to the highest speed at the optimum condition. As shown, this invention has increased the pumping speed of the diffusion pump by as much as 30 percent and also reduced fluctuation of the exhaust speed due to power fluctuations.
  • FIG. 7 shows the variation of the pressure in percentage with reference to the lowest pressure at each power which was measured as 2 to 3 X Torr for this invention and 4 to 5 X 10 Torr for the prior artv As shown, the pressure variation has been reduced to not less than one percent at the optimum power condition and, moreover, reduced further under a fluctuating power condition.
  • FIG. 8 shows the ultimate pressure which has beem improved remarkably by this invention.
  • the back streaming of diffusion oil was monitored for three hours and the measured value was 9 X 10 milligrams per minute per square centimeter for this invention as compared to 1.5 X 10' millimeter per minute per square centimeter for the prior art.
  • the disadvantages such as decomposition, bumping and back streaming in the prior art device could be completely removed and a very low and stable ultimate pressure could be obtained by this invention.
  • the heating element of this invention has a large heating surface area, the warmingup time has been shortened and the necessary power consumption has been reduced to one third.
  • An oil diffusion vacuum pump comprising a cylindrical envelope having a flat bottom, a plurality of chimneys coaxially arranged in said envelope, nozzle means formed on top of each of said chimneys, inlet means in said envelope upstream of said nozzles, outlet means in said envelope downstream of said nozzles and a heating element attached to the bottom of said envelope, wherein said bottom of the envelope is provided with a plurality of concentric annular hollow projections which are recessed from the underside and arranged so that said projections are located between said chimneys, and said heating element is provided with a plurality of concentric annular projections which are formed integrally with the body of said element and shaped to fit within the recesses of said hollow projections on the bottom of said envelope, said projections of the heating element being positioned in said recesses and in thermally coupled relationship thereto.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US00305938A 1972-05-10 1972-11-13 Oil diffusion vacuum pump Expired - Lifetime US3782861A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47046698A JPS496508A (en, 2012) 1972-05-10 1972-05-10

Publications (1)

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US3782861A true US3782861A (en) 1974-01-01

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US00305938A Expired - Lifetime US3782861A (en) 1972-05-10 1972-11-13 Oil diffusion vacuum pump

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US (1) US3782861A (en, 2012)
JP (1) JPS496508A (en, 2012)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2666384A1 (fr) * 1989-09-08 1992-03-06 Groshkov Anatoly Pompe a diffusion.
US20100326549A1 (en) * 2008-02-11 2010-12-30 Yadapalli Kondala Rao Vacuum Pump Suction Filter Meant for Collecting Impurities from Function

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5417863B2 (en, 2012) * 1973-03-22 1979-07-03
JPS5584425A (en) * 1978-12-18 1980-06-25 Toyo Boseki Production of high bulk processed yarn
JPS57117644A (en) * 1981-01-14 1982-07-22 Mitsubishi Rayon Co Fluid processing nozzle
JPS60215832A (ja) * 1984-04-04 1985-10-29 井沢　泰雄 滞留機能による複合形状異状糸の製造方法並びにエア−ノズル
JPS60187298U (ja) * 1984-05-21 1985-12-11 株式会社　上杉工業 シヤツタ捲上げ駆動機構の停止装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB477013A (en) * 1936-06-20 1937-12-20 Charles Sykes Improvements in condensation vacuum pumps

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB477013A (en) * 1936-06-20 1937-12-20 Charles Sykes Improvements in condensation vacuum pumps

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
H. A. Steinherz, High Vacuum Technology and Equipment, reprinted from Chemical Engineering, Aug. 20, 1962. *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2666384A1 (fr) * 1989-09-08 1992-03-06 Groshkov Anatoly Pompe a diffusion.
US20100326549A1 (en) * 2008-02-11 2010-12-30 Yadapalli Kondala Rao Vacuum Pump Suction Filter Meant for Collecting Impurities from Function
US8628607B2 (en) 2008-02-11 2014-01-14 Yadapalli Kondala Rao Vacuum pump suction filter meant for collecting impurities from function

Also Published As

Publication number Publication date
JPS496508A (en, 2012) 1974-01-21

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