EP1240433B1 - Dry compressing vacuum pump having a gas ballast device - Google Patents

Dry compressing vacuum pump having a gas ballast device Download PDF

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Publication number
EP1240433B1
EP1240433B1 EP00951529A EP00951529A EP1240433B1 EP 1240433 B1 EP1240433 B1 EP 1240433B1 EP 00951529 A EP00951529 A EP 00951529A EP 00951529 A EP00951529 A EP 00951529A EP 1240433 B1 EP1240433 B1 EP 1240433B1
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EP
European Patent Office
Prior art keywords
vacuum pump
gas
pressure
ballast device
ballast
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
EP00951529A
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German (de)
French (fr)
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EP1240433A1 (en
Inventor
Lutz Arndt
Thomas Dreifert
Michael HÖLZEMER
Jürgen Meyer
Frank SCHÖNBORN
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.)
Leybold GmbH
Original Assignee
Leybold Vakuum GmbH
Leybold Vacuum GmbH
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Publication of EP1240433A1 publication Critical patent/EP1240433A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
    • F04C28/28—Safety arrangements; Monitoring
    • 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
    • F04B25/00—Multi-stage pumps
    • F04B25/005—Multi-stage pumps with two cylinders
    • 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
    • F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
    • F04B37/14—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use to obtain high vacuum
    • 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
    • F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
    • F04B37/18—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use for specific elastic fluids
    • F04B37/20—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use for specific elastic fluids for wet gases, e.g. wet air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
    • F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2220/00—Application
    • F04C2220/10—Vacuum
    • F04C2220/12—Dry running
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2220/00—Application
    • F04C2220/50—Pumps with means for introducing gas under pressure for ballasting

Definitions

  • the invention relates to a dry-compressing vacuum pump with continuous or stepwise internal compression and with a gas ballast device.
  • dry-compressing vacuum pump with internal compression should be understood to mean any vacuum pump whose pump chamber or pump chambers are oil-free and in which the pump chamber volume decreases continuously or stepwise from the inlet to the outlet of the pump.
  • An example of a dry compressing vacuum pump with continuously decreasing pump head volume is a screw vacuum pump with screw flights whose pitch, depth and / or width continuously decrease from the inlet to the outlet.
  • Examples of dry-compressing vacuum pumps with gradually decreasing internal compression are multi-stage claw, roots or piston vacuum pumps in which the volume of the scoop or compression spaces decreases from stage to stage. Even with screw vacuum pumps, it is known the helical flight length so that they gradually change their properties.
  • Dry-compacting vacuum pumps are typically used in applications such as semiconductor manufacturing where toxic, very expensive or even explosive gases have to be pumped.
  • gas ballast devices in dry-compressing vacuum pumps of the type mentioned in order to avoid condensations in the outlet region.
  • the gas ballast is therefore supplied to the discharge space or pumping space sections located in the outlet area.
  • Dry-compressing vacuum pumps of the type concerned here often have pressures due to their internal compression in the outlet region, which can clearly exceed not only the suction pressure but also the atmospheric pressure. This also applies to the case of using bypass valves because these valves restrict a large gas flow due to their limited cross-sections. If a vacuum pump of the type in question was operated with open gas ballast valve in this operating phase, then gases conveyed by the pump would escape from the pump chamber into the atmosphere.
  • GB-A-13 64 854 describes the equipment of an oil-sealed vacuum pump with a check valve, as already described in the book "Modern Vacuum Practice, McGraw-Hill Book Company Europe, London, (1989), page 78 of Nigel S. Harris
  • the check valve of GB-A-13 64 854 is a spring-loaded check valve.
  • the present invention is based on the object, in a vacuum pump of the type mentioned, the gas ballast device in such a way that the risk of leakage of gases no longer exists. In addition, it should be achieved that the gas ballast operation does not additionally load the drive motor of the pump.
  • part of the gas ballast device is a check valve, it can be ensured that funded by the pump gases can not get over the gas ballast device to the outside.
  • the differential pressure valve allows the ballast gas inlet only from a certain pressure difference. By this measure it can be ensured that a Gasballasteinstory is possible only at pressures in the vacuum pump, which are below the predetermined pressure by the differential pressure valve. An unnecessary load on the pump through the introduced ballast gases can be avoided.
  • the pump 1 according to FIG. 1 comprises three stages 2, 3, 4 with the suction chamber volume decreasing from the inlet 5 to the outlet 6. Between the penultimate and the last stage an inventively designed gas ballast device 8 is connected, which in a ballast gas supply line 9 - arranged in any order - a check valve 11, a check valve 12 and a differential pressure valve 13.
  • the gas ballast operation can be switched on or off in a known manner.
  • the check valve 12 is installed so as to prevent the escape of gases, which are conveyed in the pump 1, through the conduit 9.
  • the differential pressure valve 13 causes the ballast gas enters the pump 1 with the valve 11 open only when the pressure in the ballast gas inlet falls below a predetermined pressure by the differential pressure valve.
  • FIG. 2 shows an embodiment of the gas ballast device 8, which is placed directly on the housing 15 of a vacuum pump 1. It comprises the housing 16, which is fastened by means of a screw 17 on the vacuum pump 1. The screw 17 is screwed into the conduit 18 serving to supply the ballast gas and has a shaft cavity 19 in this area on, which is connected via a lateral opening 21 with the interior 22 of the housing 16 in connection. It consists of a ball 23 (for example made of an elastomer), a seat 24 (for example made of steel) and a spring 25 which acts in the direction of the closed position.
  • a ball 23 for example made of an elastomer
  • a seat 24 for example made of steel
  • the described check valve 12 also has the function of the differential pressure valve 13.
  • the desired differential pressure can be determined by the design of the closing spring 25.
  • the interior 22 of the cylindrically shaped housing 16 has lateral openings 27.
  • a rotatable sleeve 28, which encloses the housing 16, has concentric openings 29 in the illustrated position relative to the openings 27. By rotating the sleeve 28, the opening or closing of the gas ballast supply takes place.
  • FIG. 3 shows the rotors 31, 32 of a dry-compressing vacuum pump 1 according to the screw principle. Inlet and outlet are schematically indicated by arrows 34, 35.
  • the screw threads of the rotors 31, 32 have a decreasing pitch and a decreasing width of the thread ridges. Auslassnah a gas ballast supply via the gas ballast device 8 is provided.
  • Screw vacuum pumps are advantageously operated with significant internal compression, so that there is a maximum power consumption of the drive motor at an intake pressure of about 300 mbar. At this suction pressure the supply of ballast gas is not required because the then usually high pump temperatures avoid condensation. If ballast gas were nevertheless conveyed in this operating state, this would result in additional power consumption, ie an additional engine power would have to be stored. It is therefore expedient to dimension the differential pressure valve 13 so that a gas ballast supply can be made only at a relatively high pressure difference. If, for example, the opening pressure of the differential pressure valve is 900 mbar, gas ballast could only be admitted at a pressure of approximately 100 mbar (atmospheric pressure minus 900 mbar). In this mode, the full engine power is no longer needed, so that no greater engine power must be installed for the gas ballast.
  • Figures 4 and 5 show an embodiment ( Figure 4 only partially) of a dry-compressing vacuum pump, which is designed as a multi-stage piston vacuum pump.
  • housing parts 41 and 42 are the cylindrical pump chambers 43 to 46.
  • the pistons 51 to 54 are each stepped and form eight pump chambers, which are partially connected in parallel, so that the illustrated pump has four pumping stages of decreasing volume. Its inlet is 55, its outlet 56.
  • a vacuum pump of this type is described in detail.
  • the last annular pump chamber forms the last stage of the illustrated Vacuum pump. Its inlet is 57, its outlet 58.
  • the gas ballast feed takes place in the connecting line between the outlet of the penultimate pumping stage and the inlet 57 of the last pumping stage. At this connection line the gas ballast device 8 is connected.
  • the gas ballast supply takes place via the crankshaft space 47, as is known per se from DE-A-197 09 206.
  • the inlet 57 of the last stage of the pump is connected via the line 59 with the crankshaft 47 in space. It lies in the vicinity of one end face of the crankshaft housing 48.
  • the gas ballast or purge gas inlet 8 is located in the region of the opposite side of the crankshaft housing 48. Gas flowing in via the gas inlet 8 can purge the crankshaft space 47 and / or or maintain a negative pressure therein.
  • crankcase 47 In piston vacuum pumps, it is important that the pressure in the crankcase 47 match the pressure in the pump chambers. In particular, the start of a piston vacuum pump when using AC motors having a weak starting torque is difficult when in the crankcase, a high pressure (eg atmospheric pressure) and prevails in the working spaces 43 to 46, a vacuum. This case occurs when the pump is evacuated to the recipient stopped and over the open gas ballast device 8, the crankcase 47 is flooded. However, opens the gas ballast supply only when a pressure difference is exceeded, a negative pressure can be maintained even when stopping the pump in the crankcase.
  • a high pressure eg atmospheric pressure
  • the crankcase 47 is ventilated only up to a pressure of approximately 400 mbar (atmospheric pressure minus 600 mbar).

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Abstract

The invention relates to a dry compressing vacuum pump (1) having a continuous or graduated inner compression and comprising a gas ballast device (8) having an isolating valve (11); the gas ballast device (8) also comprises a non-return valve (12), which prevents the escape of gases from the pump (1) through the gas ballast device (8) to the outside.

Description

Die Erfindung bezieht sich auf eine trockenverdichtende Vakuumpumpe mit kontinuierlicher oder stufenweiser innerer Verdichtung sowie mit einer Gasballasteinrichtung.The invention relates to a dry-compressing vacuum pump with continuous or stepwise internal compression and with a gas ballast device.

Unter "trockenverdichtende Vakuumpumpe mit innerer Verdichtung" soll jede Vakuumpumpe verstanden werden, deren Schöpfraum oder Schöpfräume ölfrei ist/sind und bei denen das Schöpfraumvolumen kontinuierlich oder stufenweise vom Einlass zum Auslass der Pumpe abnimmt. Ein Beispiel für eine trockenverdichtende Vakuumpumpe mit kontinuierlich abnehmendem Schöpfraumvolumen ist eine Schraubenvakuumpumpe mit Schraubengängen, deren Steigung, Tiefe und/oder Breite kontinuierlich vom Einlass zum Auslass abnimmt. Beispiele für trockenverdichtende Vakuumpumpen mit stufenweise abnehmender innerer Verdichtung sind mehrstufige Klauen-, Roots- oder Kolbenvakuumpumpen, bei denen das Volumen der Schöpf- oder Kompressionsräume von Stufe zu Stufe abnimmt. Auch bei Schraubenvakuumpumpen ist es bekannt, die Schraubengängänge so auszubilden, dass sie ihre Eigenschaften stufenweise verändern.The term "dry-compressing vacuum pump with internal compression" should be understood to mean any vacuum pump whose pump chamber or pump chambers are oil-free and in which the pump chamber volume decreases continuously or stepwise from the inlet to the outlet of the pump. An example of a dry compressing vacuum pump with continuously decreasing pump head volume is a screw vacuum pump with screw flights whose pitch, depth and / or width continuously decrease from the inlet to the outlet. Examples of dry-compressing vacuum pumps with gradually decreasing internal compression are multi-stage claw, roots or piston vacuum pumps in which the volume of the scoop or compression spaces decreases from stage to stage. Even with screw vacuum pumps, it is known the helical flight length so that they gradually change their properties.

Trockenverdichtende Vakuumpumpen werden in der Regel bei Applikationen (z.B. bei der Halbleiter-Fertigung) eingesetzt, bei denen giftige, sehr teure oder auch explosive Gase gefördert werden müssen.Dry-compacting vacuum pumps are typically used in applications such as semiconductor manufacturing where toxic, very expensive or even explosive gases have to be pumped.

Es ist bekannt, bei trockenverdichtenden Vakuumpumpen der erwähnten Art Gasballasteinrichtungen einzusetzen, um im auslassseitigen Bereich Kondensationen zu vermeiden. Der Gasballast wird deshalb dem oder den im Auslassbereich gelegenen Schöpfräumen oder Schöpfraumabschnitten zugeführt.It is known to use gas ballast devices in dry-compressing vacuum pumps of the type mentioned in order to avoid condensations in the outlet region. The gas ballast is therefore supplied to the discharge space or pumping space sections located in the outlet area.

Trockenverdichtende Vakuumpumpen der hier betroffenen Art weisen wegen ihrer inneren Verdichtung im auslassseitigen Bereich häufig Drücke auf, die nicht nur den Ansaugdruck sondern auch den Atmosphärendruck deutlich überschreiten können. Dieses gilt auch für den Fall, dass Bypassventile eingesetzt werden, weil diese Ventile einen großen Gasstrom auf Grund ihrer begrenzten Querschnitte drosseln. Würde eine Vakuumpumpe der hier betroffenen Art in dieser Betriebsphase mit offenem Gasballastventil betrieben, dann würden von der Pumpe geförderte Gase aus dem Schöpfraum in die Atmosphäre gelangen.Dry-compressing vacuum pumps of the type concerned here often have pressures due to their internal compression in the outlet region, which can clearly exceed not only the suction pressure but also the atmospheric pressure. This also applies to the case of using bypass valves because these valves restrict a large gas flow due to their limited cross-sections. If a vacuum pump of the type in question was operated with open gas ballast valve in this operating phase, then gases conveyed by the pump would escape from the pump chamber into the atmosphere.

Aus der DE-A-197 09 206 ist eine Vakuumpumpe der hier betroffenen Art bekannt. Die GB-A-13 64 854 beschreibt die Ausrüstung einer ölgedichteten Vakuumpumpe mit einem Rückschlagventil, wie es auch bereits im Buch "Modern Vacuum Practice", McGraw-Hill Book Company Europe, London, (1989), Seite 78 von Nigel S. Harris beschrieben wird. Beim Rückschlagventil nach der GB-A-13 64 854 handelt es sich um ein federbelastetes Rückschlagventil.From DE-A-197 09 206 a vacuum pump of the type concerned is known. GB-A-13 64 854 describes the equipment of an oil-sealed vacuum pump with a check valve, as already described in the book "Modern Vacuum Practice, McGraw-Hill Book Company Europe, London, (1989), page 78 of Nigel S. Harris The check valve of GB-A-13 64 854 is a spring-loaded check valve.

Der vorliegenden Erfindung liegt die Aufgabe zu Grunde, bei einer Vakuumpumpe der eingangs genannten Art die Gasballasteinrichtung so auszubilden, dass die Gefahr des Austritts von Gasen nicht mehr besteht. Außerdem soll erreicht werden, dass der Gasballastbetrieb den Antriebsmotor der Pumpe nicht zusätzlich belastet.The present invention is based on the object, in a vacuum pump of the type mentioned, the gas ballast device in such a way that the risk of leakage of gases no longer exists. In addition, it should be achieved that the gas ballast operation does not additionally load the drive motor of the pump.

Diese Aufgabe wird durch die kennzeichnenden Merkmale der Patentansprüche gelöst.This object is solved by the characterizing features of the claims.

Dadurch, dass Bestandteil der Gasballasteinrichtung ein Rückschlagventil ist, kann sichergestellt werden, dass von der Pumpe geförderte Gase über die Gasballasteinrichtung nicht nach außen gelangen können. Das Differenzdruckventil ermöglicht den Ballastgaseinlass nur ab einer bestimmten Druckdifferenz. Durch diese Maßnahme kann sichergestellt werden, dass ein Gasballasteintritt nur bei Drücken in der Vakuumpumpe möglich ist, die unterhalb des durch das Differenzdruckventil vorgegebenen Druckes liegen. Eine unnötige Belastung der Pumpe durch die eingelassenen Ballastgase kann dadurch vermieden werden.The fact that part of the gas ballast device is a check valve, it can be ensured that funded by the pump gases can not get over the gas ballast device to the outside. The differential pressure valve allows the ballast gas inlet only from a certain pressure difference. By this measure it can be ensured that a Gasballasteintritt is possible only at pressures in the vacuum pump, which are below the predetermined pressure by the differential pressure valve. An unnecessary load on the pump through the introduced ballast gases can be avoided.

Weitere Vorteile und Einzelheiten der Erfindung sollen an Hand von in den Figuren 1 bis 5 dargestellten Ausführungsbeispielen erläutert werden. Es zeigen

  • Figur 1 eine schematisch dargestellte mehrstufige Pumpe mit der erfindungsgemäßen Gasballasteinrichtung,
  • Figur 2 eine konkrete Ausführung der Gasballasteinrichtung,
  • Figur 3 die Rotoren einer Schraubenvakuumpumpe mit innerer Verdichtung sowie
  • Figuren 4 und 5 Beispiele für mehrstufige Kolbenvakuumpumpen.
Further advantages and details of the invention will be explained with reference to embodiments illustrated in FIGS. 1 to 5. Show it
  • 1 shows a schematically illustrated multi-stage pump with the gas ballast device according to the invention,
  • FIG. 2 shows a concrete embodiment of the gas ballast device,
  • Figure 3 shows the rotors of a screw vacuum pump with internal compression and
  • Figures 4 and 5 examples of multi-stage piston vacuum pumps.

Die Pumpe 1 nach Figur 1 umfasst drei Stufen 2, 3, 4 mit vom Einlass 5 zum Auslass 6 abnehmenden Schöpfraumvolumen. Zwischen der vorletzten und der letzten Stufe ist eine erfindungsgemäß gestaltete Gasballasteinrichtung 8 angeschlossen, die in einer Ballastgaszuführungsleitung 9 - in beliebiger Reihenfolge angeordnet - ein Absperrventil 11, ein Rückschlagventil 12 und ein Differenzdruckventil 13 aufweist.The pump 1 according to FIG. 1 comprises three stages 2, 3, 4 with the suction chamber volume decreasing from the inlet 5 to the outlet 6. Between the penultimate and the last stage an inventively designed gas ballast device 8 is connected, which in a ballast gas supply line 9 - arranged in any order - a check valve 11, a check valve 12 and a differential pressure valve 13.

Mit Hilfe des Absperrventils 11 kann in bekannter Weise der Gasballastbetrieb zu- oder abgeschaltet werden. Das Rückschlagventil 12 ist so eingebaut, dass es den Austritt von Gasen, die in der Pumpe 1 gefördert werden, durch die Leitung 9 verhindert. Das Differenzdruckventil 13 bewirkt, dass das Ballastgas bei offenem Ventil 11 nur dann in die Pumpe 1 eintritt, wenn der Druck im Bereich des Ballastgaseintritts einen durch das Differenzdruckventil vorgegebenen Druck unterschreitet.With the help of the check valve 11, the gas ballast operation can be switched on or off in a known manner. The check valve 12 is installed so as to prevent the escape of gases, which are conveyed in the pump 1, through the conduit 9. The differential pressure valve 13 causes the ballast gas enters the pump 1 with the valve 11 open only when the pressure in the ballast gas inlet falls below a predetermined pressure by the differential pressure valve.

Die Figur 2 zeigt eine Ausführungsform der Gasballasteinrichtung 8, die unmittelbar auf das Gehäuse 15 einer Vakuumpumpe 1 aufgesetzt ist. Sie umfasst das Gehäuse 16, das mit Hilfe einer Schraube 17 auf der Vakuumpumpe 1 befestigt ist. Die Schraube 17 ist in den der Zuführung des Ballastgases dienenden Kanal 18 eingeschraubt und weist in diesem Bereich einen Schafthohlraum 19 auf, der über eine seitliche Öffnung 21 mit dem Innenraum 22 des Gehäuses 16 in Verbindung steht. Im Hohlraum 19 befindet sich das Rückschlagventil 12. Es besteht aus einer Kugel 23 (z.B. aus einem Elastomer), einem Sitz 24 (z.B. aus Stahl) und einer Feder 25, die in Richtung Schließstellung wirkt.FIG. 2 shows an embodiment of the gas ballast device 8, which is placed directly on the housing 15 of a vacuum pump 1. It comprises the housing 16, which is fastened by means of a screw 17 on the vacuum pump 1. The screw 17 is screwed into the conduit 18 serving to supply the ballast gas and has a shaft cavity 19 in this area on, which is connected via a lateral opening 21 with the interior 22 of the housing 16 in connection. It consists of a ball 23 (for example made of an elastomer), a seat 24 (for example made of steel) and a spring 25 which acts in the direction of the closed position.

Das beschriebene Rückschlagventil 12 hat auch die Funktion des Differenzdruckventiles 13. Der gewünschte Differenzdruck kann über die Auslegung der Schließfeder 25 bestimmt werden.The described check valve 12 also has the function of the differential pressure valve 13. The desired differential pressure can be determined by the design of the closing spring 25.

Der Innenraum 22 des zylindrisch ausgebildeten Gehäuses 16 weist seitliche Öffnungen 27 auf. Eine das Gehäuse 16 umfassende, drehbare Hülse 28 weist in der dargestellten Position zu den Öffnungen 27 konzentrische Durchbrechungen 29 auf. Durch Verdrehen der Hülse 28 erfolgt das Öffnen oder Verschließen der Gasballastzufuhr.The interior 22 of the cylindrically shaped housing 16 has lateral openings 27. A rotatable sleeve 28, which encloses the housing 16, has concentric openings 29 in the illustrated position relative to the openings 27. By rotating the sleeve 28, the opening or closing of the gas ballast supply takes place.

Figur 3 zeigt die Rotoren 31, 32 einer trockenverdichtenden Vakuumpumpe 1 nach dem Schraubenprinzip. Einlass und Auslass sind schematisch durch Pfeile 34, 35 gekennzeichnet. Die Schraubengänge der Rotoren 31, 32 haben eine abnehmende Steigung und eine abnehmende Breite der Gewindestege. Auslassnah ist eine Gasballastzufuhr über die Gasballasteinrichtung 8 vorgesehen.FIG. 3 shows the rotors 31, 32 of a dry-compressing vacuum pump 1 according to the screw principle. Inlet and outlet are schematically indicated by arrows 34, 35. The screw threads of the rotors 31, 32 have a decreasing pitch and a decreasing width of the thread ridges. Auslassnah a gas ballast supply via the gas ballast device 8 is provided.

Schraubenvakuumpumpen werden vorteilhaft mit deutlicher innerer Verdichtung betrieben, so dass sich eine maximale Leistungsaufnahme des Antriebsmotors bei einem Ansaugdruck von etwa 300 mbar ergibt. Bei diesem Ansaugdruck ist die Zufuhr von Ballastgas nicht erforderlich, weil die dann üblicherweise hohen Pumpentemperaturen eine Kondensation vermeiden. Würde dennoch in diesem Betriebszustand Ballastgas gefördert, so würde das eine zusätzliche Leistungsaufnahme zur Folge haben, d.h., dass eine zusätzliche Motorleistung bevorratet werden müsste. Es ist deshalb zweckmäßig, das Differenzdruckventil 13 so zu bemessen, dass eine Gasballastzufuhr erst bei einer relativ hohen Druckdifferenz erfolgen kann. Beträgt beispielsweise der Öffnungsdruck des Differenzdruckventils 900 mbar, könnte Gasballast erst bei einem Druck von ca. 100 mbar (Atmosphärendruck minus 900 mbar) eingelassen werden. In diesem Betriebszustand wird die volle Motorleistung nicht mehr benötigt, so dass für den Gasballast keine größere Motorleistung installiert werden muss.Screw vacuum pumps are advantageously operated with significant internal compression, so that there is a maximum power consumption of the drive motor at an intake pressure of about 300 mbar. At this suction pressure the supply of ballast gas is not required because the then usually high pump temperatures avoid condensation. If ballast gas were nevertheless conveyed in this operating state, this would result in additional power consumption, ie an additional engine power would have to be stored. It is therefore expedient to dimension the differential pressure valve 13 so that a gas ballast supply can be made only at a relatively high pressure difference. If, for example, the opening pressure of the differential pressure valve is 900 mbar, gas ballast could only be admitted at a pressure of approximately 100 mbar (atmospheric pressure minus 900 mbar). In this mode, the full engine power is no longer needed, so that no greater engine power must be installed for the gas ballast.

Die Figuren 4 und 5 zeigen eine Ausführungsform (Figur 4 nur teilweise) einer trockenverdichtenden Vakuumpumpe, die als mehrstufige Kolbenvakuumpumpe ausgebildet ist. In ihren Schöpfraumgehäuseteilen 41 und 42 befinden sich die zylindrischen Schöpfräume 43 bis 46. Zwischen den Gehäuseteilen 41, 42 befindet sich der Kurbelwellenraum 47, dessen Gehäuse mit 48 bezeichnet ist. Die Kolben 51 bis 54 sind jeweils gestuft und bilden acht Pumpenkammern, die zum Teil parallel geschaltet sind, so dass die dargestellte Pumpe vier Pumpstufen mit abnehmendem Volumen hat. Ihr Einlass ist mit 55, ihr Auslass mit 56 bezeichnet. In der älteren deutschen Patentanmeldung 196 34 519.7 ist eine Vakuumpumpe dieser Art im einzelnen beschrieben. Die letzte ringförmige Pumpkammer bildet die letzte Stufe der dargestellten Vakuumpumpe. Ihr Einlass ist mit 57, ihr Auslass mit 58 bezeichnet.Figures 4 and 5 show an embodiment (Figure 4 only partially) of a dry-compressing vacuum pump, which is designed as a multi-stage piston vacuum pump. In their pump chamber housing parts 41 and 42 are the cylindrical pump chambers 43 to 46. Between the housing parts 41, 42 is the crankshaft space 47, whose housing is designated 48. The pistons 51 to 54 are each stepped and form eight pump chambers, which are partially connected in parallel, so that the illustrated pump has four pumping stages of decreasing volume. Its inlet is 55, its outlet 56. In the older German patent application 196 34 519.7 a vacuum pump of this type is described in detail. The last annular pump chamber forms the last stage of the illustrated Vacuum pump. Its inlet is 57, its outlet 58.

Bei der Ausführung nach Figur 4 erfolgt die Gasballastzufuhr in die Verbindungsleitung zwischen dem Auslass der vorletzten Pumpstufe und dem Einlass 57 der letzten Pumpstufe. An diese Verbindungsleitung ist die Gasballasteinrichtung 8 angeschlossen.In the embodiment of Figure 4, the gas ballast feed takes place in the connecting line between the outlet of the penultimate pumping stage and the inlet 57 of the last pumping stage. At this connection line the gas ballast device 8 is connected.

Bei der Ausführung nach Figur 5 erfolgt die Gasballastzufuhr über den Kurbelwellenraum 47, wie es aus der DE-A-197 09 206 an sich bekannt ist.In the embodiment according to FIG. 5, the gas ballast supply takes place via the crankshaft space 47, as is known per se from DE-A-197 09 206.

Der Einlass 57 der letzten Stufe der Pumpe steht über die Leitung 59 mit dem Kurbelwellenraum 47 in Verbindung. Ihre Mündung bildet einen schöpfraumnahen Ballastgaseintritt 61. Sie liegt in der Nähe der einen Stirnseite des Kurbelwellengehäuses 48. Im Bereich der gegenüberliegenden Seite des Kurbelwellengehäuses 48 befindet sich der Gasballast- oder Spülgaseinlass 8. Über den Gaseinlass 8 einströmendes Gas kann der Kurbelwellenraum 47 gespült und/oder darin ein Unterdruck aufrechterhalten werden.The inlet 57 of the last stage of the pump is connected via the line 59 with the crankshaft 47 in space. It lies in the vicinity of one end face of the crankshaft housing 48. The gas ballast or purge gas inlet 8 is located in the region of the opposite side of the crankshaft housing 48. Gas flowing in via the gas inlet 8 can purge the crankshaft space 47 and / or or maintain a negative pressure therein.

In Kolbenvakuumpumpen ist es wichtig, dass der Druck im Kurbelgehäuse 47 zum Druck in den Pumpenkammern passt. Insbesondere ist der Start einer Kolbenvakuumpumpe bei der Verwendung von Wechselstrommotoren, die ein schwaches Startmoment aufweisen, schwierig, wenn im Kurbelgehäuse ein hoher Druck (z.B. Atmosphärendruck) und in den Arbeitsräumen 43 bis 46 ein Vakuum herrscht. Dieser Fall tritt auf, wenn die Pumpe bei evakuiertem Rezipienten stillgesetzt und über die geöffnete Gasballasteinrichtung 8 das Kurbelgehäuse 47 geflutet wird. Öffnet jedoch die Gasballastzufuhr erst beim Überschreiten einer Druckdifferenz, kann auch beim Stillsetzen der Pumpe im Kurbelgehäuse ein Unterdruck aufrechterhalten werden. Beträgt beispielsweise die durch das Differenzdruckventil vorgegebene Druckdifferenz 600 mbar, dann wird bei geöffneter Gasballasteinrichtung 8 das Kurbelgehäuse 47 nur bis zu einem Druck von etwa 400 mbar (Atmosphärendruck minus 600 mbar) belüftet.In piston vacuum pumps, it is important that the pressure in the crankcase 47 match the pressure in the pump chambers. In particular, the start of a piston vacuum pump when using AC motors having a weak starting torque is difficult when in the crankcase, a high pressure (eg atmospheric pressure) and prevails in the working spaces 43 to 46, a vacuum. This case occurs when the pump is evacuated to the recipient stopped and over the open gas ballast device 8, the crankcase 47 is flooded. However, opens the gas ballast supply only when a pressure difference is exceeded, a negative pressure can be maintained even when stopping the pump in the crankcase. If, for example, the pressure difference predetermined by the differential pressure valve is 600 mbar, then with the gas ballast device 8 open, the crankcase 47 is ventilated only up to a pressure of approximately 400 mbar (atmospheric pressure minus 600 mbar).

Claims (7)

  1. Dry-compressing vacuum pump (1) having continuous or graduated internal compression, having a driving motor and having a gas-ballast device (8) which comprises an isolating valve (11),
    characterised in that the gas-ballast device (8) additionally comprises a non-return valve (12) which prevents the escape of gases from the pump (1) through the gas-ballast device (8) to the outside; that the gas-ballast device (8) moreover comprises a differential-pressure valve (13) which assumes its open position only when the difference between atmospheric pressure and the pressure present at the valve (13) on the pump side exceeds a preset value; and that the opening pressure of the differential-pressure valve (13) is so rated that it is possible to supply gas ballast only when the vacuum pump (1) is in an operating state in which the full power of the driving motor is not needed.
  2. Vacuum pump according to claim 1,
    characterised in that it is a screw-type vacuum pump.
  3. Vacuum pump according to claim 2,
    characterised in that the differential-pressure valve (13) is so designed that it opens at a pressure difference of 800 to 1000 mbar, preferably at approximately 900 mbar.
  4. Vacuum pump according to claim 1,
    characterised in that it is a multi-stage piston-type vacuum pump.
  5. Vacuum pump according to claim 4,
    characterised in that a common crankshaft chamber (47) is associated with the pistons, and that the ballast gas is supplied via said crankshaft chamber (47).
  6. Vacuum pump according to claim 4 or 5,
    characterised in that the gas-ballast device (8) is connected to a line which links the outlet of the last but one stage to the inlet (57) of the last stage.
  7. Vacuum pump according to one of claims 4 to 6,
    characterised in that differential-pressure valve (13) is so designed that it opens at a pressure difference of 500 to 1000 mbar, preferably 800 mbar.
EP00951529A 1999-12-22 2000-08-23 Dry compressing vacuum pump having a gas ballast device Expired - Lifetime EP1240433B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19962445 1999-12-22
DE19962445A DE19962445A1 (en) 1999-12-22 1999-12-22 Dry compressing vacuum pump has gas ballast device with valve that only opens when difference between atmospheric pressure and pressure on pump side of valve exceeds set value
PCT/EP2000/008201 WO2001046592A1 (en) 1999-12-22 2000-08-23 Dry compressing vacuum pump having a gas ballast device

Publications (2)

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EP1240433A1 EP1240433A1 (en) 2002-09-18
EP1240433B1 true EP1240433B1 (en) 2006-07-19

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EP00951529A Expired - Lifetime EP1240433B1 (en) 1999-12-22 2000-08-23 Dry compressing vacuum pump having a gas ballast device

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US (1) US6776588B1 (en)
EP (1) EP1240433B1 (en)
JP (1) JP2003518228A (en)
AU (1) AU6443100A (en)
DE (2) DE19962445A1 (en)
TW (1) TW482875B (en)
WO (1) WO2001046592A1 (en)

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WO2001046592A1 (en) 2001-06-28
US6776588B1 (en) 2004-08-17
EP1240433A1 (en) 2002-09-18
JP2003518228A (en) 2003-06-03
DE19962445A1 (en) 2001-06-28
AU6443100A (en) 2001-07-03
TW482875B (en) 2002-04-11
DE50013201D1 (en) 2006-08-31

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