US3666374A - Rotary molecular vacuum pump - Google Patents

Rotary molecular vacuum pump Download PDF

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Publication number
US3666374A
US3666374A US876250A US3666374DA US3666374A US 3666374 A US3666374 A US 3666374A US 876250 A US876250 A US 876250A US 3666374D A US3666374D A US 3666374DA US 3666374 A US3666374 A US 3666374A
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US
United States
Prior art keywords
pump
vacuum
high vacuum
gas
rotary
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
US876250A
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English (en)
Inventor
Willi Becker
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.)
ARTHUR PFEIFFER HOCHVAKUUMTECHNIK GMBH
PFEIFFER VAKUUMTECHNIK
Original Assignee
PFEIFFER VAKUUMTECHNIK
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 PFEIFFER VAKUUMTECHNIK filed Critical PFEIFFER VAKUUMTECHNIK
Application granted granted Critical
Publication of US3666374A publication Critical patent/US3666374A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00Axial-flow pumps
    • F04D19/02Multi-stage pumps
    • F04D19/04Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F04D19/042Turbomolecular vacuum pumps

Definitions

  • a rotary molecular vacuum pump having either one multistage compression set, or a pluralityof multi-stage compression sets connected in parallel, between the prevacuum side and the high vacuum side of the pump has at least one gas inlet which communicates with the multistage compression set, or with each such set, at an intermediate position between the pre-vacuum and high vacuum sides of the pump.
  • the invention relates to rotary molecular vacuum pumps, that is to say mechanical high vacuum and ultrahigh vacuum pumps.
  • the pressure ratio i.e. the ratio between the partial pressure of a gas at the pre-vacuum side and the partial pressure of the same gas at the high vacuum side, depends on the nature of the gas in the case of rotary molecular vacuum pumps.
  • the pressure ratio rises in approximately exponential manner with the root of the molecular weight of the gas.
  • Very high pressure ratios are the result for heavy gases, for example for oil vapours.
  • oil vapours are practically prevented from passing out of the bearings situated at the pre vacuum side or from the pre-vacuum pump, and from the pre-vacuum side to the high vacuum side of the pump, owing to the very high pressure ratios for such vapours.
  • a rotary molecular vacuum pump comprising a housing having pre-vacuum and high vacuum sides and at least one multistage compression set located in the housing between the pre-vacuum and high vacuum sides, the improvement which consists of a gas inlet communicating with the multi-stage compression set at an intermediate pressure stage thereof between the pre-vacuum and high vacuum sides.
  • valves may be employed as gas inlets. These valves need not be capable of being heated because they are not situated at the high vacuum side. Valves, for example valves made of plastics materials, possess seals consisting of elastomers, which can give off gases. This is immaterial however, since such gases can be given off by the valves only during operation of the pump, and can then only pass into the intermediate pressure stage.
  • the gases are then drawn off from the intermediate stage to the pre-vacuum side, without affecting the pressure at the high vacuum side of the pump. Moreover, and as when admitting gas to the pump from the prevacuum side, this occurs in a pump according to the invention during the running-down period of the pump which is considerably shortened because the rotor is decelerated by the friction of the gas fed in addition to hearing friction.
  • the drawing shows a longitudinal section through a rotary molecular vacuum pump comprising two multistage compression sets connected in parallel relative to the high pressure vacuum side of the pump.
  • a rotatable shaft carries rotor discs 6 which rotate between wheels or discs 7 fastened to a cylindrical housing 1 comprising a central suction connector 2 and two pre-vacuum connectors 3 one at each end of the housing 1.
  • the rotor discs 6 and stator discs 7 form sets of compression stages.
  • the prevacuum connectors communicate with a stub pipe 4 common thereto.
  • the discs in known manner, possess passages, not shown, which extend obliquely to the plane thereof. The pressure rise intervenes symmetrically, from the centre of the pump towards the end bearing plates 8 of the housing 1.
  • the driving system for the pump shaft 5, and the lubricating system for the bearings, are fastened on the end bearing plates 8.
  • the direction of delivery of the pump is indicated by arrows.
  • the gas inlets 9 for the gas inflow are situated at an intermediate compression stage of each set of the pressure stages, which latter are situated between the pre-vacuum and high vacuum sides of the pump. If desired, a plurality of gas inlets 9 may be associated with a plurality of intermediate compression stages of each set of compression stages.
  • the gas inlets 9 are connected by an inlet pipe 10 common thereto and which is closed, as at 11, by means of a valve, of known form, not shown and constructed of a material which does not have to Withstand high heat conditions.
  • the intermediate compression stages communicating with the gas inlets 9 are so far distant fl'om the high vacuum side of the pump, that gases passing from the elastomer seals of the valve into the intermediate stages cannot flow therefrom to the high vacuum side.
  • the intermediate stages are so far distant from the pre-vacuum side of the pump that the partial pressure of oil still prevailing at the inlet positions is so low that practically no oil vapour can be entrained to the high vacuum side upon flooding the pump. Admission of gas, up to atmospheric pressure, is possible at the full speed of rotation of the pump, so that its running-down time is reduced apprecia'bly.
  • a rotary molecular vacuum pump according to the invention may advantageously be employed to determine the gaseous atmosphere at the high vacuum side. For example, if a particular gas mixture is fed into the intermediate pressure stages in appropriate quantity during normal operation of the pump, the lighter ingredients of the gas mixture are preferentially concentrated at the high vacuum side, because the pressure ratios in rotary molecular vacuum pumps depend on the molecular weight of the gases, as stated. In this manner, a required gaseous atmosphere can be produced at the high vacuum side.
  • a rotary molecular vacuum pump comprising a housing having a pre' VaEuum" and high vacfiiim'sides and at least one multi-stage compression set located in the housing between the pre-vacuum and high vacuum sides, the improvement which consists of a gas inlet communicating with the multi-stage compression set at an intermediate compression stage thereof between the pro-vacuum and high vacuum sides.
  • a pump according toclaiml in which at least two multi-stage compressionsets are connected iir-parallel in the housing between" the pre-vacuum and high vacuum sides and a gas inlet 'commuuicates' -with each of said sets at an intermediate compression stage thereof between the prewacnum and high vacuum sides of the pump.
  • a pump according to claim 2' wherein the gas inlets are connected one with" theother by" an inlet pipe common thereto. I? 1 it 4.
  • a pump according to claim 1' wherein a'plui'a'iity of gas inlets communicate with a plurality 'of intermediate compression stages'o f th'e' multi-stage compression set 'between the pre-vacuunij and high vacuum sides of the pump.
  • a pump according" to claim 2. whcrein a plurality of gas inlets communicate with a plurality'o'fintermediate compression stages of eachv multi-stage'compression set between the pre-vacuum and high vacuum sides of the P p J 6.

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)
  • Applications Or Details Of Rotary Compressors (AREA)
US876250A 1968-11-20 1969-11-13 Rotary molecular vacuum pump Expired - Lifetime US3666374A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1809902A DE1809902C3 (de) 1968-11-20 1968-11-20 Mehrstufige Turbo Molekularhoch vakuumpumpe

Publications (1)

Publication Number Publication Date
US3666374A true US3666374A (en) 1972-05-30

Family

ID=5713816

Family Applications (1)

Application Number Title Priority Date Filing Date
US876250A Expired - Lifetime US3666374A (en) 1968-11-20 1969-11-13 Rotary molecular vacuum pump

Country Status (9)

Country Link
US (1) US3666374A (xx)
JP (1) JPS5017687B1 (xx)
AT (1) AT299585B (xx)
CA (1) CA920107A (xx)
CH (1) CH501840A (xx)
DE (1) DE1809902C3 (xx)
FR (1) FR2023691A1 (xx)
GB (1) GB1240744A (xx)
NL (1) NL6917165A (xx)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3969039A (en) * 1974-08-01 1976-07-13 American Optical Corporation Vacuum pump
US5011368A (en) * 1989-01-09 1991-04-30 Alcatel Cit Vacuum pump of the type having a Gaede channel
US6261052B1 (en) * 1999-01-08 2001-07-17 Fantom Technologies Inc. Prandtl layer turbine
US6435811B1 (en) 1998-05-14 2002-08-20 Leybold Vakuum Gmbh Friction vacuum pump with a stator and a rotor
US6464451B1 (en) * 1999-09-06 2002-10-15 Pfeiffer Vacuum Gmbh Vacuum pump
US20070020116A1 (en) * 2003-09-30 2007-01-25 Ikegami Mold Engineering Co., Ltd Vacuum pump

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3317868A1 (de) * 1983-05-17 1984-11-22 Leybold-Heraeus GmbH, 5000 Köln Reibungspumpe
DE4427153A1 (de) * 1994-08-01 1996-02-08 Balzers Pfeiffer Gmbh Fluteinrichtung für magnetisch gelagerte Vakuumpumpen
DE10111603A1 (de) * 2001-03-10 2002-09-12 Pfeiffer Vacuum Gmbh Gasreibungspumpe mit zusätzlichem Gaseinlass

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3969039A (en) * 1974-08-01 1976-07-13 American Optical Corporation Vacuum pump
US5011368A (en) * 1989-01-09 1991-04-30 Alcatel Cit Vacuum pump of the type having a Gaede channel
US6435811B1 (en) 1998-05-14 2002-08-20 Leybold Vakuum Gmbh Friction vacuum pump with a stator and a rotor
CN1115488C (zh) * 1998-05-14 2003-07-23 莱博尔德真空技术有限责任公司 有定子和转子的摩擦式真空泵
US6261052B1 (en) * 1999-01-08 2001-07-17 Fantom Technologies Inc. Prandtl layer turbine
US6464451B1 (en) * 1999-09-06 2002-10-15 Pfeiffer Vacuum Gmbh Vacuum pump
US20070020116A1 (en) * 2003-09-30 2007-01-25 Ikegami Mold Engineering Co., Ltd Vacuum pump
US7762763B2 (en) 2003-09-30 2010-07-27 Edwards Limited Vacuum pump

Also Published As

Publication number Publication date
GB1240744A (en) 1971-07-28
DE1809902C3 (de) 1973-11-15
DE1809902B2 (de) 1973-04-26
JPS5017687B1 (xx) 1975-06-23
NL6917165A (xx) 1970-05-22
FR2023691A1 (xx) 1970-08-21
CA920107A (en) 1973-01-30
CH501840A (de) 1971-01-15
DE1809902A1 (de) 1970-06-04
AT299585B (de) 1972-06-26

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