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EP0724689A1 - Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire - Google Patents

Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire

Info

Publication number
EP0724689A1
EP0724689A1 EP94924860A EP94924860A EP0724689A1 EP 0724689 A1 EP0724689 A1 EP 0724689A1 EP 94924860 A EP94924860 A EP 94924860A EP 94924860 A EP94924860 A EP 94924860A EP 0724689 A1 EP0724689 A1 EP 0724689A1
Authority
EP
European Patent Office
Prior art keywords
pump
cryopump
stage
vacuum
backing
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.)
Withdrawn
Application number
EP94924860A
Other languages
German (de)
English (en)
Inventor
Uwe Timm
Hans-Hermann Klein
Hans-Ulrich HÄFNER
Hans-Jürgen MUNDINGER
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.)
Balzers und Leybold Deutschland Holding AG
Original Assignee
Leybold AG
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 Leybold AG filed Critical Leybold AG
Publication of EP0724689A1 publication Critical patent/EP0724689A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
    • F04B37/06—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for evacuating by thermal means
    • F04B37/08—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for evacuating by thermal means by condensing or freezing, e.g. cryogenic pumps

Definitions

  • a cryopump is a vacuum pump which has surfaces cooled to a temperature of generally less than 120 K, on which gaseous substances condense or - when using cooled solid-state sorbents - adsorb.
  • Cryopumps currently available on the market for generating high and ultra-high vacuum are generally operated with a two-stage refrigerator. They have three pumping surface areas which are intended for the accumulation of different types of gas.
  • the first surface area is in good heat-conducting contact with the first stage of the refrigerator and, depending on the type and output of the refrigerator, has a temperature of approximately 80 K. These surface areas usually include a radiation shield and a baffle. These components protect the pump surfaces of lower temperature from incident heat radiation.
  • the pumping surfaces of the first stage are preferably used for the addition of relatively easily condensable gases, such as water vapor and carbon dioxide, by cryocondensation.
  • the second pump area is in heat-conducting contact with the second stage of the refrigerator.
  • This stage has a temperature of approximately 20 K or less during pump operation.
  • the second surface area is preferably used to remove gases that can only be condensed at lower temperatures, such as nitrogen, argon or the like, by cryocondensation and for trapping lighter gases such as H2 or He in a majority of the condensable gases mentioned.
  • the third pump area is also at the temperature of the second stage of the refrigerator (correspondingly lower in a refrigerator with three stages) and is covered with an adsorption material. Essentially, the cryosorption of light gases such as hydrogen, helium or the like takes place at these pumping surfaces.
  • cryopump It is also possible to operate a cryopump with a single-stage refrigerator. However, this must be equipped with an auxiliary pump if gases are present in an apparatus to be evacuated which do not condense at the operating temperature of the pump surfaces or are not sufficiently bound by trapping or adsorption.
  • a characteristic of a cryopump is the starting pressure. This means the pressure in the pump at which the cooling of the pump surfaces begins. With cryopumps of the type described, the starting pressure should not be higher than 10 -3 mbar (cf. "Theory and Practice of Vacuum Technology", Friedr. Vieweg & Sohn, 4th edition, page 365, paragraph 2 and “Cryopumping Theory and Practice” , Clarendon Press, Oxford, 1989, page 166, paragraph 3). This start pressure presupposes the use of backing pumps that reach end pressures of this magnitude. Such pumps include oil-sealed rotary displacement pumps, for example rotary vane vacuum pumps, which are also generally used.
  • a disadvantage of such vacuum pumps is that there is a risk of backflow of oil vapor into the apparatus to be evacuated consists. The risk of oil contamination in the apparatus and thus a disruption of the process running therein cannot be completely ruled out.
  • Oil-free vacuum pumps that reach final pressures of 10 -3 mbar and less are turbomolecular vacuum pumps and claw pumps. For cost reasons, these pumps are not used in combination with a cryopump and therefore as their backing pump.
  • a turbomolecular vacuum pump also requires an oil-sealed backing pump, so that the risk of contamination described is not completely eliminated.
  • the present invention is based on the object of specifying a method for operating a cryopump in which the outlay for the backing pump can be kept small and yet there is no longer a risk of oil contamination.
  • this object is achieved in that the cooling of the pump surfaces of the cryopump is started at a starting pressure greater than 1 mbar.
  • the starting pressure is expediently between 1 and 100 mbar, preferably between 1 and 20 mbar.
  • a pressure of this order of magnitude can be generated, for example, with the aid of a membrane vacuum pump.
  • the use of a - possibly cooled - sorptive or getter pump is also conceivable.
  • a diaphragm vacuum pump reaches a final pressure of about 10 mbar in a two-stage version, and a final pressure of about 4 mbar in a four-stage version.
  • a start pressure in this pressure range is sufficient to cool a conventional cryogenic pump.
  • the pumping surfaces of the first stage which are effective by condensation, are additionally equipped with a sorption surface and, during cooling, by heating the pumping surfaces of the second stage, the temperature of the pumping surfaces of the first stage is lower than the temperature of the first stage of cooling Second stage pumping surfaces. This ensures that residual gases accumulate on the pumping surfaces of the first stage, so that the pumping capacity of the second stage is not reduced.
  • the cryopump with 1 its housing with 2, the two-stage refrigerator with 3, the pump surfaces (condensation surfaces) with 5 and 6, which are in heat-conducting contact with the first stage 4 of the refrigerator 3 - radiation shield 5, baffle 6 - and the pump surfaces with 8 and 9, which are in heat-conducting contact with the second stage 7 of the refrigerator 3.
  • the external pump surfaces 8 serve to deposit the gases to be pumped out by condensation and trapping.
  • the pump surfaces 9 on the inside are formed by a layer of sorption material.
  • the pump interior 10 opens into the inlet opening 11 with the inlet flange 12.
  • a valve 13 is arranged in front of the inlet opening 11.
  • a diaphragm vacuum pump 15 is provided as the only backing pump, which is connected to the interior 10 of the pump 1 via the line 16 with the valve 17.
  • a membrane pump is relatively small. It can therefore - as in the exemplary embodiment according to FIG. 1 - be located in a housing 18, which in turn is attached to the housing 2 of the cryopump 1. In this housing 18 also further elements necessary for the operation of a cryopump - valves 17, 19, control electronics 21 etc. - can be accommodated, so that the cryopump according to the invention with its components necessary for operation including the backing pump forms a unit.
  • FIG. 1 shows an embodiment in which the cryopump 1 is equipped with means for flooding its interior 10.
  • a line 22 opens into the line 16 with the valve 19, which - further equipped with a pressure reducing valve 23 and a shut-off valve 24 - is connected to a gas supply bottle 25.
  • the interior 10 of the pump 1 can be flushed either by letting the valves 17 and 19 open with inert gas - preferably nitrogen - into the pump.
  • the gas mixture entraining the gases present in the pump interior flows out through the gas outlet 26 with the valve 27.
  • Another possibility of purging is that with the gas outlet 25 closed, the pump interior 10 is alternately flooded and evacuated with the aid of the gas supply 25 and the diaphragm pump 15.
  • An advantageous rinsing cycle can take place, for example, as follows: Flooding to 1,000 mbar. Pump down to 100 mbar;
  • the gas initially located in the pump interior 10 is diluted by a factor of about 10 ⁇ . After such a cycle, light gases with high thermal conductivity are practically no longer present in the pump interior 10.
  • the control of the cycle described takes place with the aid of the valves 17, 19.
  • the actuating devices of these valves are connected to the control electronics 21.
  • the actuating device designated by 28 for the valve 13 and the pressure measuring device 29 are also connected to the control electronics 21, so that the flood cycle can run automatically.
  • This also applies to methods for regenerating the pumping surfaces of the first and second stages, which are described below.
  • temperature sensors 31, 32 are assigned to these pump surfaces, which supply the control electronics 21 with signals corresponding to the temperature of the pump surfaces.
  • the cylindrical section of the pot-shaped housing 2 - and thus the largest part of the housing 2 - is double-walled.
  • an insulating vacuum can be maintained regardless of the pressure in the pump interior 10. Tests have shown that the final pressure of a diaphragm vacuum pump is sufficient to achieve effective thermal insulation as the starting pressure.
  • a line 34 with the valve 35 is therefore connected to the intermediate space 33 and opens into the line 16 leading to the inlet of the diaphragm pump 15.
  • the insulating vacuum can be generated and maintained via line 34.
  • that can Insulating vacuum can also be connected to the pump interior 10 via the line 16. If this occurs during operation of the pump 1 with the valve 17 closed and the valve 35 open, a high vacuum can be generated in the insulation space 33.
  • a total regeneration of the cryopump 1 according to the invention expediently takes place in that the refrigerator 3 is switched off and the heaters 37, 38 located in the area of the pump surfaces of the first and second stages are put into operation until the pump surfaces have reached a sufficiently high temperature (approx. 300 K).
  • the released gases leave the pump interior 10 through the gas outlet 26 (Fig. 1), possibly also in the liquid state.
  • the pump interior can then be evacuated with the aid of the diaphragm pump 15 and the cooling can be started.
  • one of the rinsing processes described above can also be carried out beforehand.
  • cryopump there is the possibility of only performing a regeneration of the pump surfaces 8, 9 of the second stage 7 (short-term regeneration).
  • T 200 K
  • the released gases leave the pump interior 10 again through the gas outlet 26.
  • the temperature of the pump surfaces 5, 6 of the first stage 7 through the one that is still in operation is kept below 160 K.
  • the cryopump 1 according to FIG. 2, which is equipped with an insulating vacuum 33, is particularly suitable for short-term regeneration.
  • This structure ensures that the temperature of the pump surfaces 5, 6 of the first stage 4 can be kept at a sufficiently low temperature not only during the short-term regeneration but also during a subsequent rinsing process.
  • FIG. 3 shows a modified embodiment of the embodiment according to FIG. 2.
  • the drive motor which is present in the refrigerator 3 and serves to move the cold head control valve also serves to drive the membrane in the membrane pump.
  • the common drive motor is shown symbolically and designated 41.
  • the drive connection 42 is located between the motor 41 and the diaphragm pump 15 arranged adjacent thereto. This is expediently equipped with a mechanically or magnetically operable clutch 43, so that the diaphragm pump, which need not be in constant operation, is switched on and off can.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Abstract

L'invention concerne un procédé d'exploitation d'une pompe cryogénique (1) avec des surfaces refroidissables de pompage (5, 6, 8, 9) et avec une pompe à vide préliminaire (15). Afin de réduire les coûts de génération du vide préliminaire ou de la pression de démarrage, ainsi que pour éliminer le danger de contamination avec de l'huile, on commence à refroidir les surfaces de pompage de la pompe cryogénique sous une pression de démarrage supérieure à 1 mbar générée par la pompe à vide préliminaire. La pompe à vide préliminaire est de préférence une pompe à vide à diaphragme.
EP94924860A 1993-10-22 1994-08-10 Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire Withdrawn EP0724689A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19934336035 DE4336035A1 (de) 1993-10-22 1993-10-22 Verfahren zum Betrieb einer Kryopumpe sowie Vakuumpumpensystem mit Kryopumpe und Vorpumpe
DE4336035 1993-10-22
PCT/EP1994/002648 WO1995011381A1 (fr) 1993-10-22 1994-08-10 Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire

Publications (1)

Publication Number Publication Date
EP0724689A1 true EP0724689A1 (fr) 1996-08-07

Family

ID=6500742

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94924860A Withdrawn EP0724689A1 (fr) 1993-10-22 1994-08-10 Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire

Country Status (3)

Country Link
EP (1) EP0724689A1 (fr)
DE (1) DE4336035A1 (fr)
WO (1) WO1995011381A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103900869A (zh) * 2014-03-03 2014-07-02 复旦大学 低温分子筛吸附泵装置

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69531313T2 (de) * 1994-04-28 2004-05-13 Ebara Corp. Regeneration einer Kryopumpe
DE19547030A1 (de) * 1995-12-15 1997-06-19 Leybold Ag Tieftemperatur-Refrigerator mit einem Kaltkopf sowie Verfahren zur Optimierung des Kaltkopfes für einen gewünschten Temperaturbereich
DE19632123A1 (de) * 1996-08-09 1998-02-12 Leybold Vakuum Gmbh Kryopumpe
US6327863B1 (en) 2000-05-05 2001-12-11 Helix Technology Corporation Cryopump with gate valve control
US11820583B2 (en) * 2020-12-17 2023-11-21 S. C. Johnson & Son, Inc. Double nozzle overcap assembly

Family Cites Families (13)

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Publication number Priority date Publication date Assignee Title
DE1184447B (de) * 1963-04-18 1964-12-31 Erich Becker Membran-Pumpe
FR1584067A (fr) * 1968-07-30 1969-12-12
CH621366A5 (fr) * 1977-05-09 1981-01-30 Balzers Hochvakuum
DE2949092A1 (de) * 1979-12-06 1981-06-11 Leybold-Heraeus GmbH, 5000 Köln Kryopumpe
DE3046458A1 (de) * 1980-12-10 1982-07-15 Leybold-Heraeus GmbH, 5000 Köln Refrigerator-kryostat
WO1986005240A1 (fr) * 1985-03-01 1986-09-12 Helix Technology Corporation Procede et dispositif de regeneration de cryopompes
DE3512614A1 (de) * 1985-04-06 1986-10-16 Leybold-Heraeus GmbH, 5000 Köln Verfahren zur inbetriebnahme und/oder regenerierung einer kryopumpe und fuer dieses verfahren geeignete kryopumpe
DE3690558T1 (fr) * 1985-10-31 1987-12-10
DE3680335D1 (de) * 1986-06-23 1991-08-22 Leybold Ag Kryopumpe und verfahren zum betrieb dieser kryopumpe.
US4763483A (en) * 1986-07-17 1988-08-16 Helix Technology Corporation Cryopump and method of starting the cryopump
DE4006755A1 (de) * 1990-03-03 1991-09-05 Leybold Ag Zweistufige kryopumpe
DE59101463D1 (de) * 1990-11-19 1994-05-26 Leybold Ag Verfahren zur regeneration einer kryopumpe sowie zur durchführung dieses verfahrens geeignete kryopumpe.
DE9111236U1 (de) * 1991-09-10 1992-07-09 Leybold AG, 6450 Hanau Kryopumpe

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9511381A1 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103900869A (zh) * 2014-03-03 2014-07-02 复旦大学 低温分子筛吸附泵装置

Also Published As

Publication number Publication date
DE4336035A1 (de) 1995-04-27
WO1995011381A1 (fr) 1995-04-27

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