US3802794A - Molecular pump comprising a pump cylinder equipped with a thread - Google Patents

Molecular pump comprising a pump cylinder equipped with a thread Download PDF

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Publication number
US3802794A
US3802794A US00238231A US23823172A US3802794A US 3802794 A US3802794 A US 3802794A US 00238231 A US00238231 A US 00238231A US 23823172 A US23823172 A US 23823172A US 3802794 A US3802794 A US 3802794A
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United States
Prior art keywords
molecular pump
wall
helical springs
thread
pump according
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Expired - Lifetime
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US00238231A
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English (en)
Inventor
F Gehring
K Jager
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DORNIER AG
DORNIER AG DT
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DORNIER AG
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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
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F04D19/044—Holweck-type pumps

Definitions

  • ABSTRACT This invention relates to an improvement in a molecular pump comprising a pump cylinder providedwith a thread and a structural element rotating therein, the
  • the present invention relates to a molecular pump comprising a pump cylinder provided with a thread and a structural part rotating therein, such as is used for feeding or conveying gases, for example in gas ultracentrifuges.
  • molecular pumps are made as separate threaded bushings and are inserted into the container of gas ultracentrifuges, or the molecular pump thread is integrated directly with the container.
  • the construction of such molecular pumps is determined by the required pressure ratios in the centrifuge and depends upon the gases to be conveyed. Accordingly, they are made as single-thread or multiple-thread internally threaded bushings having amore or less significant pitch and screw height, as well as generally with a square thread profile.
  • the processes of cutting and noncutting deformation or shaping as well as casting and injection molding are employed.
  • This object is attained, according to the present invention, by virtue of the fact that inserted in the molecular pump cylinder are prefabricated helical springs with a selective profile cross-section which are held at the wall of the molecular pump cylinder.
  • the contact surfaces of the profile cross-section of the helical springs which face the molecular pump cylindrical wall and are made to fit are so wide that the separating line between the courses of the thread and the wall must be considered as tight or sealing withrespect to the free length of the path of the gas molecules.
  • th helical springs are wound in multiple threads and like ones are telescopically inserted within each other.
  • the inside diameter of the helical springs is brought to the diameter required.
  • the helical springs are again taken out of the production sleeve and inserted directly into'the molecular pump cylinder or into the container.
  • a molecular pump cylinder is employed, it may be identical with the production sleeve.
  • the processing of the inside diameter of the helical springs also may be eliminated if the required tolerances are relatively great, or if, starting from the manufacture of the profile material including the winding of the springs up to the device, the smallest tolerances are maintained.
  • the selective profile crosssection of the inserted helical springs is preferably made either square, trapezoidal, triangular, or in a circular fashion.
  • a further embodiment of the present invention includes the series connection of several helical spring unitswith respectively different pitch in a sequence thermore, the helical springs are held at the wall of the molecular pump cylinder by virtue of the radiallyacting initial spring tension. Furthermore, the side of the profile cross-section of the prefabricated helical springs facing the wall extends parallel to the wall.
  • helical springs are wound from a suitable material by means of a device and have initially a lower pitch than is normally true for molecular pumps.
  • these helical springs are turned within each other, fixed in a device in equal intervals, and stretched or elongated until the required pitch of the molecular pump is obtained.
  • the helical spring thus produced is turned off at the outside thereof, in other words at the subsequent contact or abutment surface or area, to the tolerance fit of the inside diameter of the container and also the pump cylinder.
  • spiral or helical springs adapted to be selected, whereby a step molecularpump' is formed in the container or in a common molecular pump cylinder.
  • the ends of the helical springs are advantageously bent-off in the axial direction.
  • F IG. 1 illustrates a longitudinal cross-section through a five-thread molecular pump
  • FIG. 2 illustrates the molecular pump of FIG. 1 in a top plan view thereof
  • FIG. 3 schematically illustrates a molecular pump with several helical spring units having respectively different pitches.
  • the molecular pump 1' shown in FIG. 1 in a longitudinal cross-section has a five-threaded thread 2 having a square cross-section and profile 3.
  • the thread 2 proper consists of the helical springs 4, 5, 6, 7 and 8 (see also FIG. 2) which are wound, at a relatively low pitch, in a five-threaded manner and telescopically inserted within each other. They are pressed against the wall 9 of the container (which has been merely indicated in the figure) due to the radially acting initial spring stress thereof, and maintained in this position.
  • the spring profiles 3 When small tolerances are maintained during the processing of the 3 outside diameter D of the helical springs and with a correctly predetermined pitch S, the spring profiles 3 will rest flushwith the widecontact or bearing surfaces lflthereof in a manner such that the separating line between the contact or bearing surfaces 10, the threaded and helical springs 4, 5, 6, 7 and 8 and the wall 9 of the container isto be considered as tight. Since the free path length of the gas molecules in the vacuum prevailing in the container is very large, they cannot pass along the contact or bearing surface 10 from one thread and helical spring course into the other.
  • FIG. 2 Apparent from FIG. 2 is the molecular pump 1 in a top plan view with the individual five-threaded helical springs 4, 5, 6, 7 and 8, which are in each case arranged offset about 7 2. 7
  • FIG. 3 schematically illustrates a molecular pump 1 in'which the arrangement of several helical spring units 4, S, 6, 7 and 8, with respectively different pitches is apparent.
  • a molecular pump comprising a pump cylinder provided with a thread and a structural element rotat ing therein, the improvement which comprises prefabricated helical springs, having selective profile crosssections, held at the wall of the molecular pump cylinder,
  • the contact surfaces of the profile cross-sections facing the cylinder wall being sufficiently wide that the line of separation between the courses of thread and the wall with respect to the free length of path of gas molecules is tight.
  • a molecular pump according to claim 1 in which the springs are multiple chreaded wound helical springs.
  • a molecular pump according to claim 2 including similar helical springs telescopically inserted within each other.
  • a molecular pump according to claim 1 in which the helical springs are held at the wall of the molecular pump cylinder by radially-acting initial spring stress.
  • a molecular pump according to claim 1 in which the side of the 'profile cross-sections of the prefabricated helical springs facing the wall extend parallel to a sequence adaptedto be selected, connected in series.
  • a molecular pump according to claim 1 in which the ends of the helical springs are bent-off in the axial direction.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
  • Springs (AREA)
US00238231A 1971-04-17 1972-03-27 Molecular pump comprising a pump cylinder equipped with a thread Expired - Lifetime US3802794A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2118738A DE2118738C3 (de) 1971-04-17 1971-04-17 Molekularpumpe, bestehend aus einem mit Innengewinde versehenen zylindrischen Stator

Publications (1)

Publication Number Publication Date
US3802794A true US3802794A (en) 1974-04-09

Family

ID=5805019

Family Applications (1)

Application Number Title Priority Date Filing Date
US00238231A Expired - Lifetime US3802794A (en) 1971-04-17 1972-03-27 Molecular pump comprising a pump cylinder equipped with a thread

Country Status (5)

Country Link
US (1) US3802794A (enExample)
DE (1) DE2118738C3 (enExample)
FR (1) FR2134997A5 (enExample)
GB (1) GB1331012A (enExample)
NL (1) NL7202925A (enExample)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3912415A (en) * 1973-03-21 1975-10-14 Cit Alcatel Molecular pump and method therefor
US4826393A (en) * 1986-08-07 1989-05-02 Seiko Seiki Kabushiki Kaisha Turbo-molecular pump

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3728154C2 (de) * 1987-08-24 1996-04-18 Balzers Pfeiffer Gmbh Mehrstufige Molekularpumpe

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1065208A (en) * 1911-04-14 1913-06-17 Charles G Strickler Water turbine-wheel.
US1492846A (en) * 1922-05-11 1924-05-06 Mullard Radio Valve Co Ltd Vacuum pump
US2730297A (en) * 1950-04-12 1956-01-10 Hartford Nat Bank & Trust Co High-vacuum molecular pump
DE1010235B (de) * 1955-04-22 1957-06-13 Arthur Pfeiffer Fa Molekularpumpe

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1065208A (en) * 1911-04-14 1913-06-17 Charles G Strickler Water turbine-wheel.
US1492846A (en) * 1922-05-11 1924-05-06 Mullard Radio Valve Co Ltd Vacuum pump
US2730297A (en) * 1950-04-12 1956-01-10 Hartford Nat Bank & Trust Co High-vacuum molecular pump
DE1010235B (de) * 1955-04-22 1957-06-13 Arthur Pfeiffer Fa Molekularpumpe

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3912415A (en) * 1973-03-21 1975-10-14 Cit Alcatel Molecular pump and method therefor
US4826393A (en) * 1986-08-07 1989-05-02 Seiko Seiki Kabushiki Kaisha Turbo-molecular pump

Also Published As

Publication number Publication date
DE2118738B2 (enExample) 1974-04-11
GB1331012A (en) 1973-09-19
NL7202925A (enExample) 1972-10-19
DE2118738C3 (de) 1974-11-14
FR2134997A5 (enExample) 1972-12-08
DE2118738A1 (de) 1972-11-16

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