EP0408792A1 - Drag vacuum pump with at least one helical stage at the discharge end - Google Patents

Drag vacuum pump with at least one helical stage at the discharge end Download PDF

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Publication number
EP0408792A1
EP0408792A1 EP89113318A EP89113318A EP0408792A1 EP 0408792 A1 EP0408792 A1 EP 0408792A1 EP 89113318 A EP89113318 A EP 89113318A EP 89113318 A EP89113318 A EP 89113318A EP 0408792 A1 EP0408792 A1 EP 0408792A1
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EP
European Patent Office
Prior art keywords
gas
pump according
pump
inlet
delivery channel
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.)
Granted
Application number
EP89113318A
Other languages
German (de)
French (fr)
Other versions
EP0408792B1 (en
Inventor
Frank Fleischmann
Hans-Peter Dr. Kabelitz
Hans Kriechel
Martin Mühlhoff
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
Priority to EP89113318A priority Critical patent/EP0408792B1/en
Priority to DE89113318T priority patent/DE58905785D1/en
Priority to US07/554,721 priority patent/US5051060A/en
Priority to JP2190867A priority patent/JP2994005B2/en
Publication of EP0408792A1 publication Critical patent/EP0408792A1/en
Application granted granted Critical
Publication of EP0408792B1 publication Critical patent/EP0408792B1/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
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/68—Combating cavitation, whirls, noise, vibration or the like; Balancing by influencing boundary layers
    • F04D29/681—Combating cavitation, whirls, noise, vibration or the like; Balancing by influencing boundary layers especially adapted for elastic fluid pumps
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2250/00—Geometry
    • F05B2250/20—Geometry three-dimensional
    • F05B2250/25—Geometry three-dimensional helical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/60—Fluid transfer
    • F05D2260/607—Preventing clogging or obstruction of flow paths by dirt, dust, or foreign particles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S415/00—Rotary kinetic fluid motors or pumps
    • Y10S415/914—Device to control boundary layer

Definitions

  • the invention relates to a gas friction pump with at least one outlet-side thread stage with an annular gas delivery channel.
  • Friction pumps include molecular and turbomolecular vacuum pumps.
  • a moving rotor wall and a stationary stator wall are designed and spaced apart such that the impulses transmitted from the walls to gas molecules located between them have a preferred direction.
  • the rotor and / or stator wall are equipped with thread-like depressions or projections.
  • Turbomolecular pumps have interlocking rows of stator and rotor blades in the manner of a turbine. You need a backing pressure of around 10 ⁇ 2 mbar. In contrast, molecular pumps deliver pressures of up to 10 mbar and more, so that the effort required for generating the forevacuum is considerably less.
  • Friction pumps of the type mentioned at the outset are frequently used for evacuating chambers in which etching, coating or other vacuum treatment or manufacturing processes are carried out. These processes run the risk of solids getting into the pump. In some processes, there is even the possibility that such solids only occur during the compression of the gases, that is to say during the passage of the gases to be pumped out through the vacuum chamber. Examples are the formation of aluminum chloride in aluminum etching, ammonium chloride in coating processes, etc.
  • the present invention has for its object to design a gas friction vacuum pump of the type mentioned in such a way that on the one hand dust deposits in the outlet area can be eliminated and / or avoided and on the other hand the risk of contamination of the working chamber connected to the pump with oil vapors no longer is available.
  • the pump is equipped with a purge gas inlet which extends over the circumference of the gas delivery channel.
  • a flushing of the regions directed downstream with respect to the flushing gas inlet that is to say in particular the critical steps near the outlet, can be achieved by flushing in a flushing gas pulse (preferably nitrogen) of the order of 100 mbar l / s at operating speed. If this process is repeated at suitable intervals, removal of the deposited dust can be ensured.
  • a constant inlet of a few (1 to 5) mbar l / s purge gas preferably in the final pressure mode, causes a sufficient molecular flow in the conveying direction, so that the backflow portion and thus the oil backflow is avoided.
  • a sharp edge over which the flushing gas flows, forms the outlet-side boundary of the inlet opening of the flushing gas into the gas delivery channel. This creates a flow wall that effectively stops the backflow of oil and transports the oil molecules to the outlet.
  • the friction pump 1 shown in FIG. 1 has a first housing part 2. Part of this first housing part 2 is the outer cylinder 3, which is equipped with the flange 4. With the help of the flange 4, the friction pump 1 is connected either directly or via an attachment flange 5 to the recipient to be evacuated.
  • the friction pump has a second housing part 6, which serves to hold the rotor 7 and the stator of the drive motor 8.
  • the rotor 7 is bell-shaped. It comprises the hub part 9 and the cylindrical section 10.
  • the second housing part 6 projects into the space 11 formed by the bell-shaped rotor 7, in which the drive motor 8 and at least the upper bearing of the two rotor bearings 12 are also located.
  • the outside of the rotor 7 forms, together with the inside of the outer cylinder 3, the active pumping surfaces or the annular gas delivery channel 20.
  • the gases to be pumped are conveyed from the inlet 13 to the outlet 14.
  • a forevacuum pump, not shown, is connected to the outlet 14 during operation.
  • the two housing parts 2 and 6 are designed in such a way that they can be separated and joined together in a simple manner.
  • a locking ring 15 serves for mutual locking in the assembled state.
  • the rotor 7 is equipped with a central shaft 16, which is supported in the bearings 12.
  • the bearings 12 are in turn supported by annular disks 21, 22 in a cylindrical section 17 which is part of the second housing part 6.
  • the first housing part 2 has an inner cylindrical section 18 which immediately surrounds the cylindrical section 17 of the second housing part 6.
  • the cylindrical portion 17 is equipped with an edge 19 which is the upper end face of the cylindrical section 18 rests.
  • the cylindrical section 17 projects downward from the cylindrical section 18 or the first housing part 2, so that there is the possibility of locking the two housing parts 2 and 6 against one another with the aid of the clamping ring 15. After loosening the clamping ring 15, the unit consisting of the rotor 7 and the second housing part 6 can be pulled up out of the first housing part 2.
  • the cylindrical section 10 of the rotor 7 has a relatively thin wall, so that the rotating mass is small.
  • the threaded structures that produce the gases are part of the stator.
  • the two rings 52 and 53 are equipped on their inner sides with thread structures 56 and 57. Together with the outer surface of the cylinder section 10 of the rotor 7, these cause the gases to be conveyed in the direction of the outlet 14.
  • the rings 51, 52, 53 are held in their position in the assembled state. After loosening the top flange 5, the unit consisting of rotor 7 and housing part 6 and then the rings 51, 52, 53 can first be pulled out of the housing part 3.
  • the ring 51 has a smooth inner surface.
  • the structures 58 which produce the gases are provided on the rotor itself. For example, they can be designed as described in European patent application 88116749.8. These structures are designed as webs, the width and pitch of which decrease from the suction side to the pressure side. Thereby this results in an effective filling level 51, 58 with improved delivery performance.
  • the cylindrical housing 3 is equipped with a radial bore 61 to which a purge gas line, not shown, can be connected.
  • the bore 61 opens into an annular channel 62, in which the purge gas collects, so that it can be fed uniformly over the entire circumference of the gas delivery channel 20.
  • the enlarged representation of the geometry of the flushing gas inlet in FIG. 2 shows that the flushing gas is supplied between the two threaded step rings 52 and 53.
  • the collecting channel 62 is formed by an inner groove 63 in the housing part 3.
  • one of the two rings 52, 53 is provided with approximately radially directed grooves or is knurled so that there is a passage gap 65 extending over the entire circumference.
  • This passage gap 65 is followed by a volume expansion 66, which is formed by taking back the lower edge of the ring 52 and its thread structure 56. This results in an inlet opening 67 which is wider than the passage gap 65 and extends over the entire circumference of the gas delivery channel 20.
  • the delivered gas molecules move in the annular gas delivery channel 20 in the direction of arrow 68.
  • the flushing gas passes through the bore 61 into the annular channel 62 and is distributed over the circumference of the pump. It then passes through the gap 65 at high speed and reaches the volume extension 66, in which it partially calms down. Since this calming is only possible towards the inlet side, the flow velocity of the purge gas is maintained along the end face of the ring 53. This creates a "flow wall", which effectively retains oil creeping on the thread bases 69 in the direction of the inlet 70 as well as molecular backflows present in the area of the groove bases, indicated by the arrows 71. The molecules entrained by the purge gas are promoted towards the outlet.
  • a sharp-edged design of the transition 72 of the groove bases 69 to the inlet-side end face of the ring 53 promotes the desired effect.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Positive Displacement Air Blowers (AREA)

Abstract

Die Erfindung bezieht sich auf eine Gasreibungspumpe (1) mit mindestens einer auslaßseitigen Gewindestufe (10, 57) mit ringförmigem Gasförderkanal (20); um Staubablagerungen im auslaßseitigen Bereich zu vermeiden oder zu beseitigen, wird vorgeschlagen, daß die Pumpe mit einem sich über den Umfang des Gasförderkanals (20) erstreckenden Spülgaseinlaß ausgerüstet ist.The invention relates to a gas friction pump (1) with at least one threaded step (10, 57) on the outlet side with an annular gas delivery channel (20); In order to avoid or remove dust deposits in the area on the outlet side, it is proposed that the pump be equipped with a purge gas inlet which extends over the circumference of the gas delivery channel (20).

Description

Die Erfindung bezieht sich auf eine Gasreibungspumpe mit minde­stens einer auslaßseitigen Gewindestufe mit ringförmigem Gas­förderkanal.The invention relates to a gas friction pump with at least one outlet-side thread stage with an annular gas delivery channel.

Zu den Reibungspumpen gehören Molekular- und Turbomolekularvakuum­pumpen. Bei Molekularpumpen sind eine sich bewegende Rotorwand und eine ruhende Statorwand so gestaltet und beabstandet, daß die von den Wandungen auf dazwischen befindliche Gasmoleküle über­tragene Impulse eine bevorzugte Richtung haben. In der Regel sind Rotor und/oder Statorwand mit gewindeförmigen Vertiefungen oder Vorsprüngen ausgerüstet. Turbomolekularpumpen weisen nach Art einer Turbine ineinandergreifende Stator- und Rotorschaufelreihen auf. Sie benötigen einen Vorvakuumdruck von etwa 10⁻² mbar. Demgegenüber fördern Molekularpumpen bis zu Drücken von 10 mbar und mehr, so daß der für die Vorvakuumerzeugung erforderliche Aufwand wesentlich geringer ist.Friction pumps include molecular and turbomolecular vacuum pumps. In the case of molecular pumps, a moving rotor wall and a stationary stator wall are designed and spaced apart such that the impulses transmitted from the walls to gas molecules located between them have a preferred direction. As a rule, the rotor and / or stator wall are equipped with thread-like depressions or projections. Turbomolecular pumps have interlocking rows of stator and rotor blades in the manner of a turbine. You need a backing pressure of around 10⁻² mbar. In contrast, molecular pumps deliver pressures of up to 10 mbar and more, so that the effort required for generating the forevacuum is considerably less.

Reibungspumpen der eingangs erwähnten Art, wie sie beispielsweise aus dcr De-OS 37 05 912 bekannt sind, werden häufig zur Evakuie­rung von Kammern eingesetzt, in denen Ätz-, Beschichtungs- oder andere Vakuumbehandlungs- oder Herstellverfahren durchgeführt werden. Bei diesen Prozessen besteht die Gefahr, daß Feststoffe in die Pumpe gelangen. Bei einigen Prozessen besteht sogar die Möglichkeit, daß solche Feststoffe erst während der Verdichtung der Gase, also während des Durchtritts der abzupumpenden Gase durch die Vakuumkammer entstehen. Beispiele sind die Bildung von Aluminiumchlorid beim Aluminium-Ätzen, von Amoniumchlorid bei Beschichtungsverfahren usw.Friction pumps of the type mentioned at the outset, as are known, for example, from DE-OS 37 05 912, are frequently used for evacuating chambers in which etching, coating or other vacuum treatment or manufacturing processes are carried out. These processes run the risk of solids getting into the pump. In some processes, there is even the possibility that such solids only occur during the compression of the gases, that is to say during the passage of the gases to be pumped out through the vacuum chamber. Examples are the formation of aluminum chloride in aluminum etching, ammonium chloride in coating processes, etc.

Lagern sich Feststoffe dieser Art in den Gasförderkanälen der Vakuumpumpe ab, dann verringert sich der Durchmesser dieser Kanäle, was eine Reduzierung der Leistung der Vakuumpumpe zur Folge hat. Gerade bei den Reibungspumpen, die zumindest im auslaßseitigen Bereich als Molekularpumpe ausgebildet sind, hat sich herausgestellt, daß sich die unerwünschten Feststoffe in den auslaßnahen Gewindestrukturen ablagern.If solids of this type are deposited in the gas delivery channels of the vacuum pump, the diameter of these channels is reduced, which results in a reduction in the performance of the vacuum pump. Especially with the friction pumps, which are designed as molecular pumps at least in the area on the outlet side, it has been found that the undesired solids are deposited in the thread structures near the outlet.

Eine weitere Gefahr besteht darin, daß die staubförmigen Fest­stoffe in den Motorraum gelangen, in welchem sich auch die Lagerungen befinden. Üblicherweise handelt es sich um schmier­mittelversorgte Wälzlagerungen, die bei Staubanfall einem er­höhten Verschleiß unterworfen sind.Another danger is that the dust-like solids get into the engine compartment, in which the bearings are also located. Rolling bearings supplied with lubricant are usually involved and are subject to increased wear in the event of dust.

Bei Reibungspumpen, die bei den erwähnten Pumpprozessen einge­setzt werden, ist aus den geschilderten Gründen ein erhöhter Wartungsaufwand erforderlich. Die Beseitigung von Verschmutzungen aus der Gasförderkanälen und aus dem Motorraum setzt eine Demon­tage der Pumpe voraus, welche aufwendig und deshalb kostspielig ist.For friction pumps, which are used in the pumping processes mentioned, increased maintenance is required for the reasons described. The removal of dirt from the gas delivery channels and from the engine compartment requires dismantling the pump, which is complex and therefore costly.

Schließlich treten bei Gewindepumpstufen vorzugsweise im End­druckbereich Molekular- bzw. Ölrückströmungen auf. Dies ist der Fall, weil kaum noch eine Molekularströmung in Förderrichtung besteht und der optisch freie Querschnitt der Gewindekanäle relativ groß ist. Insbesondere beim Enddruckbetrieb bilden sich in den Gewindestufen Gaskreisläufe aus. Im Bereich der Rotorwand strömen die wenigen noch vorhandenen Moleküle in Förderrichtung. Im Bereich des Grundes der Gewindegänge strömen die Gase zurück und fördern dort die Ölrückströmung. Es besteht deshalb die große Gefahr, daß aus der Vorvakuumpumpe stammende Ölmoleküle in den Rezipienten gelangen und den darin ablaufenden Prozeß stören.Finally, in the case of threaded pump stages, molecular or oil backflows occur preferably in the final pressure range. This is the case because there is hardly any molecular flow in the conveying direction and the optically free cross-section of the thread channels is relatively large. Gas cycles are formed in the threaded stages, especially in the final pressure mode. In the area of the rotor wall, the few remaining molecules flow in the direction of conveyance. In the area of the bottom of the threads, the gases flow back and promote the backflow of oil. There is therefore a great danger that oil molecules originating from the fore-vacuum pump will get into the recipient and interfere with the process taking place therein.

Insbesondere bei der Herstellung von Halbleiterbauteilen sind selbst extrem kleine Öldampfkonzentrationen äußerst schädlich.Particularly in the manufacture of semiconductor components, even extremely small oil vapor concentrations are extremely harmful.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, eine Gasreibungsvakuumpumpe der eingangs erwähnten Art so zu gestal­ten, daß zum einen Staubablagerungen im auslaßseitigen Bereich beseitigt und/oder vermieden werden können und daß zum anderen die Gefahr der Kontamination der an die Pumpe angeschlossenen Arbeitskammer mit Öldämpfen nicht mehr vorhanden ist.The present invention has for its object to design a gas friction vacuum pump of the type mentioned in such a way that on the one hand dust deposits in the outlet area can be eliminated and / or avoided and on the other hand the risk of contamination of the working chamber connected to the pump with oil vapors no longer is available.

Erfindungsgemäß werden diese Ziele dadurch erreicht, daß die Pumpe mit einem sich über den Umfang des Gasförderkanals er­streckenden Spülgaseinlaß ausgerüstet ist. Bei einer in dieser Weise ausgebildeten Pumpe kann durch Einlaß eines Spülgaspulses (vorzugsweise Stickstoff) von größenordnungsmäßig 100 mbar l/s bei Betriebsdrehzahl ein kräftiges Durchspülen der in Bezug auf den Spülgaseinlaß stromabwärts gerichteten Bereiche, also insbe­sondere der kritischen auslaßnahen Stufen, erreicht werden. Wenn dieser Vorgang in geeigneten Zeitabständen wiederholt wird, kann eine Abführung des abgelagerten Staubs gewährleistet werden. Ein ständiger Einlaß von einigen wenigen (1 bis 5) mbar l/s Spülgas, vorzugsweise im Enddruckbetrieb, bewirkt einen ausreichenden molekularen Fluß in Förderrichtung, so daß der Rückströmungsan­teil und damit die Ölrückströmung vermieden wird.According to the invention, these objectives are achieved in that the pump is equipped with a purge gas inlet which extends over the circumference of the gas delivery channel. In the case of a pump designed in this way, a flushing of the regions directed downstream with respect to the flushing gas inlet, that is to say in particular the critical steps near the outlet, can be achieved by flushing in a flushing gas pulse (preferably nitrogen) of the order of 100 mbar l / s at operating speed. If this process is repeated at suitable intervals, removal of the deposited dust can be ensured. A constant inlet of a few (1 to 5) mbar l / s purge gas, preferably in the final pressure mode, causes a sufficient molecular flow in the conveying direction, so that the backflow portion and thus the oil backflow is avoided.

Besonders vorteilhaft ist es, wenn eine scharfe, vom Spülgas mit hoher Geschwindigkeit überströmte Kante die auslaßseitige Be­grenzung der Eintrittsöffnung des Spülgases in den Gasförderkanal bildet. Dadurch entsteht eine Strömungswand, die die Ölrückströ­mung wirksam stoppt und die Ölmoleküle zum Auslaß transportiert.It is particularly advantageous if a sharp edge, over which the flushing gas flows, forms the outlet-side boundary of the inlet opening of the flushing gas into the gas delivery channel. This creates a flow wall that effectively stops the backflow of oil and transports the oil molecules to the outlet.

Weitere Vorteile und Einzelheiten der Erfindung sollen anhand von in den Figuren 1 und 2 dargestellten Ausführungsbeispielen erläutert werden. Es zeigen:

  • - Figur 1 einen Schnitt durch eine Reibungspumpe nach der Erfindung und
  • - Figur 2 einen vergrößterten Schnitt durch den Spülgaseinlaß.
Further advantages and details of the invention will be explained on the basis of the exemplary embodiments illustrated in FIGS. 1 and 2. Show it:
  • - Figure 1 is a section through a friction pump according to the invention and
  • - Figure 2 is an enlarged section through the purge gas inlet.

Die in Figur 1 dagestellte Reibungspumpe 1 weist ein erstes Gehäuseteil 2 auf. Bestandteil dieses ersten Gehäuseteils 2 ist der äußere Zylinder 3, der mit dem Flansch 4 ausgerüstet ist. Mit Hilfe des Flansches 4 wird die Reibungspumpe 1 entweder unmit­telbar oder über einen Aufsatzflansch 5 an den zu evakuierenden Rezipienten angeschlossen.The friction pump 1 shown in FIG. 1 has a first housing part 2. Part of this first housing part 2 is the outer cylinder 3, which is equipped with the flange 4. With the help of the flange 4, the friction pump 1 is connected either directly or via an attachment flange 5 to the recipient to be evacuated.

Die Reibungspumpe weist einen zweiten Gehäuseteil 6 auf, der der Halterung des Rotors 7 und des Stators des Antriebsmotors 8 dient. Der Rotor 7 ist glockenförmig ausgebildet. Er umfaßt den Nabenteil 9 und den zylindrischen Abschnitt 10. Das zweite Gehäuseteil 6 ragt in den vom glockenförmigen Rotor 7 gebildeten Raum 11 hinein, in welchem sich auch der Antriebsmotor 8 und zumindest das obere Lager der beiden Rotorlagerungen 12 befindet. Die Außenseite des Rotors 7 bildet zusammen mit der Innenseite des äußeren Zylinders 3 die pumpaktiven Flächen bzw. den ring­förmigen Gasförderkanal 20. Die zu pumpenden Gase werden vom Einlaß 13 zum Auslaß 14 gefördert. An den Auslaß 14 wird während des Betriebes eine nicht dargestellte Vorvakuumpumpe angeschlos­sen.The friction pump has a second housing part 6, which serves to hold the rotor 7 and the stator of the drive motor 8. The rotor 7 is bell-shaped. It comprises the hub part 9 and the cylindrical section 10. The second housing part 6 projects into the space 11 formed by the bell-shaped rotor 7, in which the drive motor 8 and at least the upper bearing of the two rotor bearings 12 are also located. The outside of the rotor 7 forms, together with the inside of the outer cylinder 3, the active pumping surfaces or the annular gas delivery channel 20. The gases to be pumped are conveyed from the inlet 13 to the outlet 14. A forevacuum pump, not shown, is connected to the outlet 14 during operation.

Die beiden Gehäuseteile 2 und 6 sind derart gestaltet, daß sie in einfacher Weise voneinander getrennt und zusammengefügt werden können. Der gegenseitigen Arretierung im montierten Zustand dient ein Klemmring 15.The two housing parts 2 and 6 are designed in such a way that they can be separated and joined together in a simple manner. A locking ring 15 serves for mutual locking in the assembled state.

Der Rotor 7 ist mit einer zentralen Welle 16 ausgerüstet, die sich in den Lagerungen 12 abstützt. Die Lagerungen 12 ihrerseits stützen sich über Ringscheiben 21, 22 in einem zylindrischen Abschnitt 17 ab, der Bestandteil des zweiten Gehäuseteils 6 ist.The rotor 7 is equipped with a central shaft 16, which is supported in the bearings 12. The bearings 12 are in turn supported by annular disks 21, 22 in a cylindrical section 17 which is part of the second housing part 6.

Das erste Gehäuseteil 2 weist einen inneren zylindrischen Ab­schnitt 18 auf, der den zylindrischen Abschnitt 17 des zweiten Gehäuseteiles 6 unmittelbar umgibt. Der zylindrische Abschnitt 17 ist mit einem Rand 19 ausgerüstet, der der oberen Stirnseite des zylindrischen Abschnittes 18 aufliegt. Der zylindrische Abschnitt 17 ragt nach unten aus dem zylindrischen Abschnitt 18 bzw. dem ersten Gehäuseteil 2 hervor, so daß die Möglichkeit besteht, die beiden Gehäuseteile 2 und 6 mit Hilfe des Klemmringes 15 gegen­seitig zu arretieren. Nach dem Lösen des Klemmringes 15 kann die aus dem Rotor 7 und dem zweiten Gehäuseteil 6 bestehende Einheit nach oben aus dem ersten Gehäuseteil 2 herausgezogen werden.The first housing part 2 has an inner cylindrical section 18 which immediately surrounds the cylindrical section 17 of the second housing part 6. The cylindrical portion 17 is equipped with an edge 19 which is the upper end face of the cylindrical section 18 rests. The cylindrical section 17 projects downward from the cylindrical section 18 or the first housing part 2, so that there is the possibility of locking the two housing parts 2 and 6 against one another with the aid of the clamping ring 15. After loosening the clamping ring 15, the unit consisting of the rotor 7 and the second housing part 6 can be pulled up out of the first housing part 2.

Innerhalb des weitgehend nach außen abgedichteten Raumes 11, gebildet vom Rotor 7 und dem Gehäuseteil 6, befindet sich eine Schmierölversorgung für die Lager 12 der Welle 16. Die Welle 16 ragt mit einem konischen unteren Abschnitt 31 in einen Ölsumpf 32 hinein und ist mit einem zentralen Ölkanal 33 ausgerüstet. Über seitliche Bohrungen 34 und 35 gelangt das im zentralen Kanal 33 aufsteigende Öl infolge der Fliehkräfte zu den Lagern 12.Within the largely outwardly sealed space 11, formed by the rotor 7 and the housing part 6, there is a lubricating oil supply for the bearings 12 of the shaft 16. The shaft 16 projects with a conical lower section 31 into an oil sump 32 and is with a central one Oil channel 33 equipped. The oil rising in the central channel 33 reaches the bearings 12 as a result of the centrifugal forces via lateral bores 34 and 35.

Der zylindrische Abschnitt 10 des Rotors 7 weist eine relativ dünne Wandung auf, so daß die rotierende Masse klein ist. Die die Förderung der Gase bewirkenden Gewindestrukturen sind Bestandteil des Stators. Im zylindrischen Gehäuse 3 befinden sich Ringe 51, 52 und 53, die sich auf den Stufen 54 und 55 im Gehäuse 3 ab­stützen. Die beiden Ringe 52 und 53 sind auf ihren Innenseiten mit Gewindestrukturen 56 und 57 ausgerüstet. Diese bewirken zusammen mit der äußeren Oberfläche des Zylinderabschnittes 10 des Rotors 7 die Förderung der Gase in Richtung Auslaß 14. Mit Hilfe des Aufsatzflansches 5 werden die Ringe 51, 52, 53 im montierten Zustand in ihrer Lage festgehalten. Nach dem Lösen des Aufsatzflansches 5 können zunächst die aus Rotor 7 und Gehäuse­teil 6 bestehende Einheit und danach die Ringe 51, 52, 53 nach oben aus dem Gehäuseteil 3 herausgezogen werden.The cylindrical section 10 of the rotor 7 has a relatively thin wall, so that the rotating mass is small. The threaded structures that produce the gases are part of the stator. In the cylindrical housing 3 there are rings 51, 52 and 53 which are supported on the steps 54 and 55 in the housing 3. The two rings 52 and 53 are equipped on their inner sides with thread structures 56 and 57. Together with the outer surface of the cylinder section 10 of the rotor 7, these cause the gases to be conveyed in the direction of the outlet 14. With the aid of the attachment flange 5, the rings 51, 52, 53 are held in their position in the assembled state. After loosening the top flange 5, the unit consisting of rotor 7 and housing part 6 and then the rings 51, 52, 53 can first be pulled out of the housing part 3.

Der Ring 51 hat eine glatte innere Oberfläche. Die die Förderung der Gase bewirkenden Strukturen 58 sind am Rotor selbst vorgese­hen. Sie können beispielsweise so ausgebildet werden, wie es in der europäischen Patentanmeldung 88116749.8 beschrieben ist. Diese Strukturen sind als Stege ausgebildet, deren Breite und deren Steigung von der Saugseite zur Druckseite abnehmen. Dadurch ergibt sich eine wirksame Einfüllstufe 51, 58 mit verbesserter Förderleistung.The ring 51 has a smooth inner surface. The structures 58 which produce the gases are provided on the rotor itself. For example, they can be designed as described in European patent application 88116749.8. These structures are designed as webs, the width and pitch of which decrease from the suction side to the pressure side. Thereby this results in an effective filling level 51, 58 with improved delivery performance.

Das zylindrische Gehäuse 3 ist mit einer Radialbohrung 61 ausge­rüstet, an die eine nicht dargestellte Spülgasleitung anschließ­bar ist. Die Bohrung 61 mündet in einen Ringkanal 62, in dem sich das Spülgas sammelt, so daß es gleichmäßig über den gesamten Umfang des Gasförderkanals 20 zugeführt werden kann.The cylindrical housing 3 is equipped with a radial bore 61 to which a purge gas line, not shown, can be connected. The bore 61 opens into an annular channel 62, in which the purge gas collects, so that it can be fed uniformly over the entire circumference of the gas delivery channel 20.

Der vergrößerten Darstellung der Geometrie des Spülgaseinlasses in Figur 2 ist entnehmbar, daß die Spülgaszuführung zwischen den beiden Gewindestufenringen 52 und 53 erfolgt. Der Sammelkanal 62 wird von einer Innennut 63 im Gehäuseteil 3 gebildet. Im Bereich ihrer Stoßstelle 64 ist einer der beiden Ringe 52, 53 mit etwa radial gerichteten Rillen versehen oder gerändelt ausgebildet, so daß ein über den gesamten Umfang sich erstreckender Durchtritts­spalt 65 vorhanden ist. An diesen Durchtrittsspalt 65 schließt sich eine Volumenerweiterung 66 an, die durch Zurücknehmen der unteren Kante des Ringes 52 und seiner Gewindestruktur 56 gebildet ist. Dadurch ergibt sich eine gegenüber dem Durchtrittsspalt 65 erweiterte Eintrittsöffnung 67, welche sich über den gesamten Umfang des Gasförderkanals 20 erstreckt.The enlarged representation of the geometry of the flushing gas inlet in FIG. 2 shows that the flushing gas is supplied between the two threaded step rings 52 and 53. The collecting channel 62 is formed by an inner groove 63 in the housing part 3. In the area of its abutment 64, one of the two rings 52, 53 is provided with approximately radially directed grooves or is knurled so that there is a passage gap 65 extending over the entire circumference. This passage gap 65 is followed by a volume expansion 66, which is formed by taking back the lower edge of the ring 52 and its thread structure 56. This results in an inlet opening 67 which is wider than the passage gap 65 and extends over the entire circumference of the gas delivery channel 20.

Während des Betriebs einer mit dem beschriebenen Spülgaseinlaß ausgerüsteten Reibungspumpe 1 bewegen sich die geförderten Gasmoleküle im ringförmigen Gasförderkanal 20 in Richtung des Pfeiles 68. Das Spülgas tritt durch die Bohrung 61 in den Ring­kanal 62 und verteilt sich über den Umfang der Pumpe. Danach tritt es mit hoher Geschwindigkeit durch den Spalt 65 hindurch und gelangt in die Volumenerweiterung 66, in der es sich zum Teil beruhigt. Da diese Beruhigung nur zur Einlaßseite hin möglich ist, wird die Strömungsgeschwindigkeit des Spülgases entlang der Stirnseite des Ringes 53 aufrechterhalten. Dadurch entsteht eine "Strömungswand", die sowohl auf den Gewindegründen 69 in Richtung Einlaß kriechendes Öl 70 als auch im Bereich der Nutengründe vorhandene Molekularrückströmungen, angedeutet durch die Pfeile 71, wirksam zurückhält. Die vom Spülgas mitgerissenen Moleküle werden in Richtung Auslaß gefördert. Eine möglichst scharfkantige Ausbildung des Überganges 72 der Nutengründe 69 zur einlaßsei­tigen Stirnseite des Ringes 53 fördert die gewünschte Wirkung.During the operation of a friction pump 1 equipped with the flushing gas inlet described, the delivered gas molecules move in the annular gas delivery channel 20 in the direction of arrow 68. The flushing gas passes through the bore 61 into the annular channel 62 and is distributed over the circumference of the pump. It then passes through the gap 65 at high speed and reaches the volume extension 66, in which it partially calms down. Since this calming is only possible towards the inlet side, the flow velocity of the purge gas is maintained along the end face of the ring 53. This creates a "flow wall", which effectively retains oil creeping on the thread bases 69 in the direction of the inlet 70 as well as molecular backflows present in the area of the groove bases, indicated by the arrows 71. The molecules entrained by the purge gas are promoted towards the outlet. A sharp-edged design of the transition 72 of the groove bases 69 to the inlet-side end face of the ring 53 promotes the desired effect.

Claims (9)

1. Gasreibungspumpe (1) mit mindestens einer auslaßseitigen Gewindestufe (10, 57) mit ringförmigem Gasförderkanal (20), dadurch gekennzeichnet, daß sie mit einem sich über den Umfang des Gasförderkanals (20) erstreckenden Spülgaseinlaß ausgerüstet ist.1. Gas friction pump (1) with at least one outlet-side thread stage (10, 57) with an annular gas delivery channel (20), characterized in that it is equipped with a purge gas inlet extending over the circumference of the gas delivery channel (20). 2. Pumpe nach Anspruch 1, dadurch gekennzeichnet, daß eine scharfe, vom Spülgas mit hoher Geschwindigkeit überströmte Kante (72) die auslaßseitige Begrenzung der Eintrittsöffnung (67) des Spülgases in den Gasförderkanal (20) bildet.2. Pump according to claim 1, characterized in that a sharp edge (72) over which the flushing gas flows at high speed forms the outlet-side boundary of the inlet opening (67) of the flushing gas into the gas delivery channel (20). 3. Pumpe nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß ein ringförmiger Sammelkanal (62) für das Spülgas vorgesehen ist.3. Pump according to claim 1 or 2, characterized in that an annular collecting channel (62) is provided for the purge gas. 4. Pumpe nach Anspruch 3, dadurch gekennzeichnet, daß sich an den ringförmigen Sammelkanal (62) ein ringförmiger Durch­trittsspalt (65) anschließt.4. Pump according to claim 3, characterized in that an annular passage gap (65) adjoins the annular collecting channel (62). 5. Pumpe nach Anspruch 4, dadurch gekennzeichnet, daß der Durchtrittsspalt (65) in einen sich zum Einlaß der Pumpe hin erstreckenden Beruhigungsraum (66) übergeht.5. Pump according to claim 4, characterized in that the passage gap (65) merges into a calming space (66) extending towards the inlet of the pump. 6. Pumpe nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß sie mindestens zwei Gewindestufen (10, 56 und 10, 57) aufweist, und daß sich der Spülgaseinlaß zwischen diesen beiden Gewindestufen befindet.6. Pump according to one of the preceding claims, characterized in that it has at least two thread stages (10, 56 and 10, 57), and that the purge gas inlet is located between these two thread stages. 7. Pumpe nach Anspruch 6, dadurch gekennzeichnet, daß separate Ringe (52, 53) vorgesehen sind, welche die die Gasförderung bewirkenden Strukturen (56, 57) tragen.7. Pump according to claim 6, characterized in that separate rings (52, 53) are provided which carry the structures producing the gas production (56, 57). 8. Pumpe nach Anspruch 7, dadurch gekennzeichnet, daß sich der Spülgaseinlaß im Bereich der Stoßstelle (64) der beiden Ringe (52, 53) befindet.8. Pump according to claim 7, characterized in that the purge gas inlet is in the region of the joint (64) of the two rings (52, 53). 9. Pumpe nach Anspruch 8, dadurch gekennzeichnet, daß eine der im Bereich der Stoßstelle (64) befindlichen Stirnseiten der Ringe (52, 53) mit einer Rändelung oder Riffelung zur Bildung des Durchtrittsspaltes (65) ausgerüstet ist.9. Pump according to claim 8, characterized in that one of the end faces of the rings (52, 53) located in the region of the joint (64) is equipped with knurling or corrugation to form the passage gap (65).
EP89113318A 1989-07-20 1989-07-20 Drag vacuum pump with at least one helical stage at the discharge end Expired - Lifetime EP0408792B1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP89113318A EP0408792B1 (en) 1989-07-20 1989-07-20 Drag vacuum pump with at least one helical stage at the discharge end
DE89113318T DE58905785D1 (en) 1989-07-20 1989-07-20 GAS FRICTION PUMP WITH AT LEAST ONE OUTLET THREAD LEVEL.
US07/554,721 US5051060A (en) 1989-07-20 1990-07-19 Gas friction pump having an outlet-side helical stage
JP2190867A JP2994005B2 (en) 1989-07-20 1990-07-20 Gas friction pump with at least one outlet thread stage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP89113318A EP0408792B1 (en) 1989-07-20 1989-07-20 Drag vacuum pump with at least one helical stage at the discharge end

Publications (2)

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EP0408792A1 true EP0408792A1 (en) 1991-01-23
EP0408792B1 EP0408792B1 (en) 1993-09-29

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EP89113318A Expired - Lifetime EP0408792B1 (en) 1989-07-20 1989-07-20 Drag vacuum pump with at least one helical stage at the discharge end

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EP (1) EP0408792B1 (en)
JP (1) JP2994005B2 (en)
DE (1) DE58905785D1 (en)

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WO1993023672A1 (en) * 1992-05-16 1993-11-25 Leybold Aktiengesellschaft Gas friction vacuum pump
EP0731278A1 (en) * 1995-03-10 1996-09-11 Balzers-Pfeiffer GmbH Molecular vacuum pump with cooling gas device
WO1997015760A1 (en) * 1995-10-20 1997-05-01 Leybold Vakuum Gmbh Friction vacuum pump with intermediate inlet
DE19632874A1 (en) * 1996-08-16 1998-02-19 Leybold Vakuum Gmbh Friction vacuum pump
EP0985828A1 (en) * 1998-09-10 2000-03-15 Alcatel Method and device to prevent deposits in a turbomolecular pump having magnetic or gas bearings
WO2000046508A1 (en) * 1999-02-02 2000-08-10 Varian, Inc. Dual inlet vacuum pumps
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EP0731278A1 (en) * 1995-03-10 1996-09-11 Balzers-Pfeiffer GmbH Molecular vacuum pump with cooling gas device
WO1997015760A1 (en) * 1995-10-20 1997-05-01 Leybold Vakuum Gmbh Friction vacuum pump with intermediate inlet
US6030189A (en) * 1995-10-20 2000-02-29 Leybold Vakuum Gmbh Friction vacuum pump with intermediate inlet
DE19632874A1 (en) * 1996-08-16 1998-02-19 Leybold Vakuum Gmbh Friction vacuum pump
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WO2000046508A1 (en) * 1999-02-02 2000-08-10 Varian, Inc. Dual inlet vacuum pumps
US6193461B1 (en) 1999-02-02 2001-02-27 Varian Inc. Dual inlet vacuum pumps
DE19933332A1 (en) * 1999-07-16 2001-01-18 Leybold Vakuum Gmbh Friction vacuum pump for use in a pressure control system and pressure control system with a friction vacuum pump of this type
US6702544B1 (en) 1999-07-16 2004-03-09 Leybold Vakuum Gmbh Friction vacuum pump for use in a system for regulating pressure and pressure regulating system comprising a friction vacuum pump of this type

Also Published As

Publication number Publication date
JPH0357898A (en) 1991-03-13
JP2994005B2 (en) 1999-12-27
US5051060A (en) 1991-09-24
DE58905785D1 (en) 1993-11-04
EP0408792B1 (en) 1993-09-29

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