EP3638906A1 - Multi-stage rotary piston pump - Google Patents

Multi-stage rotary piston pump

Info

Publication number
EP3638906A1
EP3638906A1 EP18726990.7A EP18726990A EP3638906A1 EP 3638906 A1 EP3638906 A1 EP 3638906A1 EP 18726990 A EP18726990 A EP 18726990A EP 3638906 A1 EP3638906 A1 EP 3638906A1
Authority
EP
European Patent Office
Prior art keywords
stage
pump
pumping
roots pump
pump according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP18726990.7A
Other languages
German (de)
French (fr)
Inventor
Thomas Dreifert
Roland Müller
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 GmbH
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 GmbH filed Critical Leybold GmbH
Publication of EP3638906A1 publication Critical patent/EP3638906A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • 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
    • F04C18/126—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 radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots 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
    • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
    • F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
    • 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
    • F04C25/00—Adaptations of pumps for special use of pumps for elastic fluids
    • F04C25/02—Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
    • 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
    • F04C28/10—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by changing the positions of the inlet or outlet openings with respect to the working chamber
    • F04C28/16—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by changing the positions of the inlet or outlet openings with respect to the working chamber using lift valves
    • 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
    • F04C18/165—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 having more than two rotary pistons with parallel axes
    • 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
    • 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
    • F04C2240/00—Components
    • F04C2240/30—Casings or housings
    • 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
    • F04C2270/00—Control; Monitoring or safety arrangements
    • F04C2270/19—Temperature
    • 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
    • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • F04C29/04—Heating; Cooling; Heat insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/02—Light metals
    • F05C2201/021—Aluminium

Definitions

  • the invention relates to a multi-stage Roots pump.
  • Roots pumps usually have bidentate, arranged in a pump chamber rotary piston. Furthermore, multidentate rotary pistons with, for example, three or four teeth are known. The two rotary pistons are driven in opposite directions, so that a gas is sucked through an inlet and discharged through an outlet through the individual resulting chambers. In multi-stage Roots pumps several such rotary piston pairs are arranged one behind the other. The outlet of a pumping stage is connected to the inlet of the subsequent pumping stage.
  • Roots pumps Usually today large amounts of gas are used for pumping combinations of Roots pumps and backing pumps, which have a correspondingly high pumping speed.
  • multi-stage Roots pumps have a pumping rate of about 600 m 3 / h. Such a pumping speed, for example, the pumps from Kashiyama called SD600C on.
  • SD600C the pumps from Kashiyama
  • large screw or multi-stage Roots pumps are used as backing pumps in these pump systems.
  • the object of the invention is to provide a multi-stage Roots pump, with which the combination of Wälzkolben- and backing pump can be replaced by a Roots pump with a comparable pumping speed.
  • the multi-stage Roots pump according to the invention has two shafts arranged in a housing, each of which carries a plurality of rotary pistons.
  • the rotary pistons may also be formed integrally with the respective shaft.
  • Corresponding rotary pistons each form a rotary piston pair, wherein a plurality of rotary piston pairs are provided, each having a pumping stage form.
  • Adjacent pump stages are connected to each other via connection channels.
  • the outlet of a pumping stage is connected to the inlet of the next pumping stage via connection channels.
  • the first pumping stage in the flow direction is connected to the pump inlet.
  • the pump inlet to be evacuated lock chamber or the like is connected.
  • the pump outlet is connected to the last pumping stage in the flow direction.
  • the multi-stage Roots pump has a high built-in volume ratio.
  • the built-in volume ratio defines the delivery volume of the inlet stage to the delivery volume of the outlet stage.
  • the built-in volume ratio is at least 15, preferably at least 20 and more preferably at least 25. Due to the provision of a high built volume ratio and due to the provision of a multi-stage Roots pump, it is possible, high pumping speeds of at least 1500 m 3 / h and in particular more than 2500 m 3 / h to realize.
  • the built-in volume ratio can be achieved by varying the length of the steps as well as by varying the outer diameter of the rotary pistons and the number of teeth as well as a combination of these variations.
  • the multistage roots pump prefferably have at least three stages, in particular at least five stages.
  • the number of stages is preferably where n is the number of levels and VR is the built-in volume ratio.
  • over-compression is meant the compression of the gas to an intermediate pressure greater than the outlet pressure of the pump, i. usually everything above 1 bar is called over-compression.
  • At least the first two and in particular the first three pumping stages are connected to a discharge channel, in which in turn a corresponding relief valve is arranged. These are the first stages in the flow direction.
  • valves of the two and all other pumping stages are open.
  • the remaining pump stages run empty.
  • closing of the discharge valve connected to the second pumping stage takes place and the pumping takes place either via the remaining pumping stages or via the third pumping stage through a discharge channel connected to the third pumping stage.
  • the valves of the first and second pumping stages are closed, the valves of the third and optionally further pumping stages are open. According to the number of stages of the vacuum pump and the number of associated with the corresponding pumping stages discharge channels this can be continued accordingly.
  • the relief channels are preferably connected respectively to the environment and / or the pump outlet.
  • a connection of the pump outlets is particularly advantageous if the pumped gases can not be passed directly into the environment, since they are, for example, toxic or still need to be cleaned.
  • the pressure stages or the sizes of the pump chambers, in which the corresponding rotary piston pairs are arranged for selecting a pumping stage are designed such that the pressure difference of adjacent pump stages is less than 500 mbar.
  • the housing therefore has on its outer side cooling ribs and / or arranged in the housing walls cooling channels.
  • the cooling channels are flowed through by a cooling medium, in particular a cooling liquid.
  • the connection channels arranged in the housing, with which the pump stages are connected are arranged in the vicinity of cooling channels.
  • the connection channels may also be partially surrounded by cooling channels in order to achieve extremely effective cooling.
  • an inner surface of the pump chambers, in which the rotary pistons are arranged is as large as possible.
  • a part of the inner surface of a pump chamber which preferably has a time-averaged pressure of over 200 mbar at final pressure operation,
  • S is the highest measured suction capacity of the vacuum pump between inlet pressures at the pump inlet of 1-50 mbar and
  • VR is the volume ratio.
  • the speed ⁇ 60007min, preferably ⁇ 45007min, more preferably ⁇ 30007min.
  • the connecting channels have a z. B. by ribs enlarged surface to effectively cool the gas.
  • the gas temperature is indirectly after the last stage below 300 ° C, preferably below 250 ° C, and more preferably below 200 ° C. These temperatures are measured at an ambient temperature of about 20 ° C and a coolant inlet temperature of about 20 ° C, and at nominal cooling water flow (ie the temperature increase of the cooling water is less than 20 ° C from inlet to outlet) and operation with air.
  • the rotary pistons and preferably also the shafts carrying the rotary pistons are made of a steel alloy or of steel.
  • the combination of steel shaft and aluminum housing is advantageous because the thermal expansion coefficients are significantly different.
  • the housing preferably comprises aluminum or an aluminum alloy.
  • Another significant advantage of the multi-stage Roots pump according to the invention is that the required space can be significantly reduced.
  • the provision of backing pumps is no longer required, or at least smaller backing pumps can be used.
  • the outlet of the first pumping stage is connected to a bypass line.
  • a valve is arranged in the Umweg für a valve is arranged.
  • the bypass line is connected in particular to the inlet of the first pumping stage.
  • a drive motor can be operated here in particular for a period of 5 to 30 seconds above the rated power. In particular, it is possible to increase the power by 50%, preferably by 100% compared to the rated power.
  • Fig. 1 is a schematic sectional view of a multi-stage Roots pump according to the invention.
  • Fig. 2 is a schematic cross section of a Wälzkolbencut with two teeth.
  • a multi-stage Roots pump according to the invention has a plurality of pump stages 12, 14, 16, 18 in a pump housing 10.
  • Per pump stage two rotary pistons are provided.
  • Corresponding rotary lobe 20 designed as a bidentate rotary piston are shown schematically in FIG. 2 shown in cross section.
  • the two rotary pistons 20 rotate in opposite directions, so that gas is sucked in the direction of an arrow 22 through a gas inlet 24 and discharged through an opposite outlet 26 in the direction of an arrow 28 again.
  • a respective rotary piston of the rotary piston pairs is arranged on a common shaft 30 (FIG. 1).
  • the multi-stage Roots pump has two successive in Fig. 1 shafts 30, which are each mounted in the housing 10.
  • the drive of the waves takes place for example via gears 32.
  • the gas to be delivered is sucked in via a pump inlet 34 and discharged via a pump outlet 36.
  • the individual stages 12, 14, 16 18 are each connected via connecting channels 38 with each other.
  • Each pumping stage 12, 14, 16, 18 has an outlet 40, through which the gas to be delivered is conveyed into the connecting channel 38.
  • the outlet 42 of the last pumping stage 18 is connected to the pump outlet 36.
  • the pumping stages 14, 16, 18 each have an inlet 44 which is in each case connected to the corresponding connecting channel 38.
  • a valve 46, 48, 50 which may be, for example, a weighted ball valve, is provided at each inlet 44 . Via the valves, a connection between the inlets 44 and a discharge channel 52 can take place.
  • the first stage 12 may be further connected to a detour line, not shown.
  • Such a bypass line is connected to the outlet 40 of the first stage 12 and has a bypass line valve.
  • the bypass line is usually connected to the inlet 34 of the first stage.
  • the discharge channel 52 is connected to the pump outlet 36.
  • the pumping speed of the individual pumping stages decreases in the conveying direction.
  • the pumping speed of a subsequent pumping stage is half the pumping speed of the preceding pumping stage.
  • the pressure is usually about 1000 mbar.
  • the Roots pump can be ideally operated according to the table below, if pressure losses in valves and lines are neglected.
  • the table applies to a 2: 1 graduation ratio for each pump stage, ie. the subsequent stage has half the pumping speed of the previous pumping stage.
  • the pressure at the pump inlet 34 is insufficient.
  • the pressure Pi is the pressure prevailing at the inlet of the second stage 14
  • P 2 is the pressure prevailing at the inlet of the third stage 16
  • P3 is the pressure prevailing at the inlet of the fourth stage 18.
  • the valve Vi is the valve 46
  • the valve V 2 is the valve 48
  • the valve V3 is the valve 50.
  • "0” means that the valve is opened and “g” that the valve is closed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Rotary Pumps (AREA)

Abstract

The invention relates to a multi-stage rotary piston pump comprising two shafts in a housing, which support multiple rotary pistons. Corresponding rotary pistons form a respective rotary piston pair, wherein multiple rotary piston pairs are provided which form a respective pump stage. Neighbouring pump stages are each connected to one another via connection channels. The multi-stage rotary piston pump also comprises a pump inlet that is connected to the first pump stage, as well as a pump outlet that is connected to the last pump stage. According to the invention, the built-in volume ratio is at least 15, so that high pumping capacities of at least 1500 m3/h can be achieved.

Description

Mehrstufige Wälzkolbenpumpe  Multi-stage Roots pump
Die Erfindung betrifft eine mehrstufige Wälzkolbenpumpe. The invention relates to a multi-stage Roots pump.
Wälzkolbenpumpen weisen üblicherweise zweizähnige, in einem Pumpenraum angeordnete Drehkolben auf. Ferner sind auch mehrzähnige Drehkolben mit beispielsweise drei oder vier Zähnen bekannt. Die beiden Drehkolben werden gegenläufig angetrieben, so dass durch die einzelnen entstehenden Kammern ein Gas durch einen Einlass angesaugt und durch einen Auslass wieder ausgestoßen wird. Bei mehrstufigen Wälzkolbenpumpen sind mehrere derartige Drehkolbenpaare hintereinander angeordnet. Der Auslass einer Pumpstufe ist mit dem Einlass der nachfolgenden Pumpstufe verbunden. Roots pumps usually have bidentate, arranged in a pump chamber rotary piston. Furthermore, multidentate rotary pistons with, for example, three or four teeth are known. The two rotary pistons are driven in opposite directions, so that a gas is sucked through an inlet and discharged through an outlet through the individual resulting chambers. In multi-stage Roots pumps several such rotary piston pairs are arranged one behind the other. The outlet of a pumping stage is connected to the inlet of the subsequent pumping stage.
Zum Evakuieren großer Schleusenkammern oder anderer großer Kammern muss eine große Menge Gas gepumpt werden. Dies muss häufig in kurzen Zeiträumen erfolgen. Hierzu ist es bekannt, Wälzkolbenpumpen in Kombination mit in Reihe in Strömungsrichtung nachgeordnet geschalteten Vorvakuumpumpen vorzusehen. Derartige Systeme werden auch verwendet, wenn große Gasflüsse kontinuierlich gepumpt werden müssen, wobei dies insbesondere bei geringen Ansaugdrücken unter 20 mbar (absolut) erfolgt. To evacuate large lock chambers or other large chambers, a large amount of gas must be pumped. This often has to be done in short periods of time. For this purpose, it is known to provide Wälzkolbenpumpen in combination with downstream in series in the flow direction Vorvakuumpumpen. Such systems are also used when large gas flows have to be pumped continuously, especially at low suction pressures below 20 mbar (absolute).
Üblicherweise werden zum Pumpen großer Gasmengen heute Kombinationen von Wälzkolbenpumpen und Vorvakuumpumpen eingesetzt, die ein entsprechend hohes Saugvermögen aufweisen. Bekannte auf dem Markt befindliche mehrstufige Wälzkolbenpumpen weisen ein Saugvermögen von ca. 600 m3/h auf. Ein derartiges Saugvermögen weisen beispielsweise die Pumpen der Firma Kashiyama mit der Bezeichnung SD600C auf. Üblicherweise werden in diesen Pumpensystemen große Schrauben- oder mehrstufige Wälzkolbenpumpen als Vorvakuumpumpen eingesetzt. Usually today large amounts of gas are used for pumping combinations of Roots pumps and backing pumps, which have a correspondingly high pumping speed. Known on the market multi-stage Roots pumps have a pumping rate of about 600 m 3 / h. Such a pumping speed, for example, the pumps from Kashiyama called SD600C on. Usually, large screw or multi-stage Roots pumps are used as backing pumps in these pump systems.
Aufgabe der Erfindung ist es, eine mehrstufige Wälzkolbenpumpe zu schaffen, mit der die Kombination aus Wälzkolben- und Vorvakuumpumpe durch eine Wälzkolbenpumpe mit vergleichbarem Saugvermögen ersetzt werden kann. The object of the invention is to provide a multi-stage Roots pump, with which the combination of Wälzkolben- and backing pump can be replaced by a Roots pump with a comparable pumping speed.
Die Lösung der Aufgabe erfolgt erfindungsgemäß durch die Merkmale des Anspruchs 1. The object is achieved according to the invention by the features of claim 1.
Grundsätzlich besteht die Problematik, dass bei großen Vakuumpumpen mit entsprechend großem Saugvermögen das Verhältnis aus den internen Oberflächen zu dem Fördervolumen bzw. zur umgesetzten Leistung ungünstig ist. Dies hat zur Folge, dass in derartigen Pumpen hohe Temperaturen auftreten. Hohe Temperaturen resultieren in einer großen Wärmeausdehnung . Bei mehrstufigen Wälzkolbenpumpen erfolgt die durch die hohe Temperatur hervorgerufene Wärmeausdehnung insbesondere in axialer Richtung, so dass die Drehkolben axial, d .h. in Längsrichtung der Achse, die die Drehkolben trägt, verschoben werden . Dies führt dazu, dass die Pumpkammern, in denen die Drehkolben angeordnet sind, einen entsprechend großen Axialspalt aufweisen müssten. Dies hätte jedoch wiederum negative Auswirkungen auf die Pumpleistung und somit die Temperatur. Basically, there is the problem that in large vacuum pumps with a correspondingly high pumping speed, the ratio of the internal surfaces to the delivery volume or the converted power is unfavorable. As a result, high temperatures occur in such pumps. High temperatures result in a large thermal expansion. In multi-stage Roots pumps caused by the high temperature thermal expansion takes place in particular in the axial direction, so that the rotary pistons axially, d .h. in the longitudinal direction of the axis, which carries the rotary pistons, to be moved. This results in that the pumping chambers in which the rotary pistons are arranged, would have to have a correspondingly large axial gap. However, this would in turn have negative effects on the pump power and thus the temperature.
Die erfindungsgemäße mehrstufige Wälzkolbenpumpe weist zwei in einem Gehäuse angeordnete Wellen auf, die jeweils mehrere Drehkolben tragen. Hierbei können die Drehkolben auch einstückig mit der jeweiligen Welle ausgebildet sein. Korrespondierende Drehkolben bilden jeweils ein Drehkolbenpaar aus, wobei mehrere Drehkolbenpaare vorgesehen sind, die jeweils eine Pumpstufe ausbilden. Benachbarte Pumpstufen sind über Verbindungskanäle miteinander verbunden. Hierbei ist jeweils der Auslass einer Pumpstufe mit dem Einlass der nächsten Pumpstufe über Verbindungskanäle verbunden. Ferner ist die in Strömungsrichtung erste Pumpstufe mit dem Pumpeneinlass verbunden. Mit dem Pumpeneinlass ist die zu evakuierende Schleusenkammer oder dergleichen verbunden . Mit der in Strömungsrichtung letzten Pumpstufe ist der Pum- penauslass verbunden . The multi-stage Roots pump according to the invention has two shafts arranged in a housing, each of which carries a plurality of rotary pistons. Here, the rotary pistons may also be formed integrally with the respective shaft. Corresponding rotary pistons each form a rotary piston pair, wherein a plurality of rotary piston pairs are provided, each having a pumping stage form. Adjacent pump stages are connected to each other via connection channels. In this case, in each case the outlet of a pumping stage is connected to the inlet of the next pumping stage via connection channels. Furthermore, the first pumping stage in the flow direction is connected to the pump inlet. The pump inlet to be evacuated lock chamber or the like is connected. The pump outlet is connected to the last pumping stage in the flow direction.
Erfindungsgemäß weist die mehrstufige Wälzkolbenpumpe ein hohes eingebautes Volumenverhältnis auf. Das eingebaute Volumenverhältnis definiert das Fördervolumen der Einlassstufe zu dem Fördervolumen der Auslassstufe. Erfindungsgemäß beträgt das eingebaute Volumenverhältnis mindestens 15, vorzugsweise mindestens 20 und besonders bevorzugt mindestens 25. Aufgrund des Vorsehens eines hohen eingebauten Volumenverhältnisses und aufgrund des Vorsehens einer mehrstufigen Wälzkolbenpumpe ist es möglich, hohe Saugvermögen von insbesondere mindestens 1500 m3/h und insbesondere mehr als 2500 m3/h zu realisieren. Das eingebaute Volumenverhältnis kann durch Variation der Länge der Stufen wie auch durch Variation der Außendurchmesser der Drehkolben sowie der Zähnezahl wie auch durch eine Kombination dieser Variationen erfolgen. According to the invention, the multi-stage Roots pump has a high built-in volume ratio. The built-in volume ratio defines the delivery volume of the inlet stage to the delivery volume of the outlet stage. According to the invention, the built-in volume ratio is at least 15, preferably at least 20 and more preferably at least 25. Due to the provision of a high built volume ratio and due to the provision of a multi-stage Roots pump, it is possible, high pumping speeds of at least 1500 m 3 / h and in particular more than 2500 m 3 / h to realize. The built-in volume ratio can be achieved by varying the length of the steps as well as by varying the outer diameter of the rotary pistons and the number of teeth as well as a combination of these variations.
Besonders bevorzugt ist es zur Erzielung besonders hoher Saugvermögen, dass die mehrstufige Wälzkolbenpumpe mindestens drei Stufen, insbesondere mindestens fünf Stufen aufweist. To achieve particularly high pumping speeds, it is particularly preferred for the multistage roots pump to have at least three stages, in particular at least five stages.
Für die Anzahl der Stufen gilt vorzugsweise wobei n die Anzahl der Stufen und VR das eingebaute Volumenverhältnis ist. The number of stages is preferably where n is the number of levels and VR is the built-in volume ratio.
Ferner ist es bevorzugt, zur Verminderung von Überkompression mindestens eine der Pumpstufen mit einem Entlastungskanal zu verbinden, wobei in dem Entlastungskanal bzw. zwischen Pumpstufe und Entlastungskanal ein Entlastungsventil angeordnet ist. Unter Überkompression versteht man die Verdichtung des Gases auf einen Zwischendruck, der größer als der Auslassdruck der Pumpe ist, d.h. in der Regel wird alles oberhalb von 1 bar als Überkompression bezeichnet. Durch Verringerung der Überkompression wird die maximal benötigte Motorleistung reduziert.  Further, it is preferable to connect to reduce over-compression at least one of the pumping stages with a discharge channel, wherein in the discharge channel or between the pumping stage and discharge channel a relief valve is arranged. By over-compression is meant the compression of the gas to an intermediate pressure greater than the outlet pressure of the pump, i. usually everything above 1 bar is called over-compression. By reducing the over-compression, the maximum required engine power is reduced.
Besonders bevorzugt ist es, dass zumindest die ersten beiden und insbesondere die ersten drei Pumpstufen mit einem Entlastungskanal, in dem wiederum ein entsprechendes Entlastungsventil angeordnet ist, verbunden sind. Hierbei handelt es sich um die ersten Stufen in Strömungsrichtung . It is particularly preferred that at least the first two and in particular the first three pumping stages are connected to a discharge channel, in which in turn a corresponding relief valve is arranged. These are the first stages in the flow direction.
Durch Vorsehen derartiger Entlastungskanäle ist es möglich, in den einzelnen aufeinanderfolgenden Pumpstufen unterschiedliche Saugvermögen zu realisieren. Ist das Saugvermögen einer zweiten Stufe geringer als das einer ersten Stufe, so kann insbesondere zu Beginn einer Abpumpphase ein Teil des gepumpten Gases unmittelbar über den Entlastungskanal ausgestoßen werden. Entsprechend ist dies je nach Phase der Abpumpung bei unterschiedlichen Saugvermögen zwischen den in Strömungsrichtung nachgeordneten Stufen möglich. By providing such relief channels, it is possible to realize different pumping speeds in the individual successive pumping stages. If the pumping speed of a second stage is lower than that of a first stage, then, in particular at the beginning of a pumping-off phase, part of the pumped gas can be expelled directly via the discharge channel. Accordingly, this is possible depending on the phase of the pumping at different pumping speeds between the downstream in the flow direction stages.
Die erfindungsgemäße mehrstufige Wälzkolbenpumpe kann daher insbesondere derart betrieben werden, dass bei einem anfangs hohen Druck von beispielsweise 1000 mbar die erste Pumpstufe das zu pumpende Gas insbesondere vollständig über den Entlastungskanal ausstößt. Zu Beginn des Abpumpvorgangs ist insbesondere das Ventil der ersten Stufe geöffnet. Die übrigen Pumpstufen laufen in dieser Pumpphase leer, d .h. sie fördern geringe Mengen an Gas. Auch derartige "leerlaufende" Stufen fördern Gas, durch die Entlas- tungsventile bauen sie allerdings keinen Druck auf. Zu einem späteren Zeitpunkt, wenn der Druck entsprechend gesunken ist, d .h. beispielsweise 500 mbar beträgt, schließt das mit der ersten Pumpstufe verbundene Entlüftungsventil, und das gepumpte Gas wird insbesondere vollständig über den mit der zweiten Pumpstufe verbundenen Entlastungskanal ausgestoßen. Die Ventile der zwei und aller weiteren Pumpstufen sind offen. Die übrigen Pumpstufen laufen leer. Zu einem späteren Zeitpunkt bei einem wiederum niedrigen Druck von beispielsweise 250 mbar erfolgt ein Schließen des mit der zweiten Pumpstufe verbundenen Entlastungsventils, und das Pumpen erfolgt entweder über die restlichen Pumpstufen oder über die dritte Pumpstufe durch einen mit der dritten Pumpstufe verbundenen Entlastungskanal. Die Ventile der ersten und zweiten Pumpstufe sind geschlossen, die Ventile der dritten und ggf. weiterer Pumpstufen sind offen. Nach Anzahl der Stufen der Vakuumpumpe und nach Anzahl der mit den entsprechenden Pumpstufen verbundenen Entlastungskanäle kann dies entsprechend fortgesetzt werden. The multi-stage Roots pump according to the invention can therefore be operated in particular such that at an initially high pressure of, for example, 1000 mbar, the first pumping stage discharges the gas to be pumped in particular completely via the discharge channel. At the beginning of the Abpumpvorgangs particular the valve of the first stage is open. The remaining pump stages run empty in this pumping phase, ie. they produce small amounts of gas. Even such "idle" stages promote gas, through the discharge However, they do not create any pressure. At a later time, when the pressure has fallen accordingly, ie. For example, is 500 mbar, the venting valve connected to the first pumping stage closes, and the pumped gas is in particular completely discharged via the discharge channel connected to the second pumping stage. The valves of the two and all other pumping stages are open. The remaining pump stages run empty. At a later time at a low pressure of, for example 250 mbar, closing of the discharge valve connected to the second pumping stage takes place and the pumping takes place either via the remaining pumping stages or via the third pumping stage through a discharge channel connected to the third pumping stage. The valves of the first and second pumping stages are closed, the valves of the third and optionally further pumping stages are open. According to the number of stages of the vacuum pump and the number of associated with the corresponding pumping stages discharge channels this can be continued accordingly.
Die Entlastungskanäle sind vorzugsweise jeweils mit der Umgebung und/oder dem Pumpenauslass verbunden. Eine Verbindung der Pumpenauslässe ist insbesondere dann vorteilhaft, wenn die gepumpten Gase nicht unmittelbar in die Umgebung geleitet werden können, da sie beispielsweise toxisch sind oder noch gereinigt werden müssen. The relief channels are preferably connected respectively to the environment and / or the pump outlet. A connection of the pump outlets is particularly advantageous if the pumped gases can not be passed directly into the environment, since they are, for example, toxic or still need to be cleaned.
Über eine weitere bevorzugte Ausführungsform sind die Druckstufen bzw. die Größen der Pumpräume, in denen die korrespondierenden Drehkolbenpaare zur Auswahl einer Pumpstufe angeordnet sind, derart ausgebildet, dass die Druckdifferenz benachbarter Pumpstufen kleiner als 500 mbar ist. Hierdurch kann auch eine Reduzierung der Maximaltemperatur erreicht werden, so dass insbesondere aufgrund der vorgesehenen Vielzahl an Pumpstufen für die gesamte mehrstufige Wälzkolbenpumpe ein sehr hohes Saugvermögen erzielt werden kann. Desweiteren ist es zur Erzielung eines insbesondere hohen Saugvermögens vorteilhaft, eine gute Kühlung vorzusehen. In bevorzugter Ausführungsform weist das Gehäuse daher an seiner Außenseite Kühlrippen und/oder in den Gehäusewänden angeordnete Kühlkanäle auf. Die Kühlkanäle sind von einem Kühlmedium, insbesondere einer Kühlflüssigkeit, durchströmt. Desweiteren ist es bevorzugt, dass die in dem Gehäuse angeordneten Verbindungskanäle, mit denen die Pumpstufen verbunden sind, in der Nähe von Kühlkanälen angeordnet sind. Beispielsweise können die Verbindungskanäle auch teilweise von Kühlkanälen umgeben sein, um eine äußerst effektive Kühlung zu erzielen. By way of a further preferred embodiment, the pressure stages or the sizes of the pump chambers, in which the corresponding rotary piston pairs are arranged for selecting a pumping stage, are designed such that the pressure difference of adjacent pump stages is less than 500 mbar. In this way, a reduction of the maximum temperature can be achieved, so that in particular due to the intended number of pump stages for the entire multi-stage Roots pump, a very high pumping speed can be achieved. Furthermore, to achieve a particularly high pumping speed, it is advantageous to provide good cooling. In a preferred embodiment, the housing therefore has on its outer side cooling ribs and / or arranged in the housing walls cooling channels. The cooling channels are flowed through by a cooling medium, in particular a cooling liquid. Furthermore, it is preferred that the connection channels arranged in the housing, with which the pump stages are connected, are arranged in the vicinity of cooling channels. For example, the connection channels may also be partially surrounded by cooling channels in order to achieve extremely effective cooling.
Hinsichtlich der Kühlung ist es desweiteren besonders bevorzugt, dass eine innere Oberfläche der Pumpräume, in denen die Drehkolben angeordnet sind, möglichst groß ist. Insbesondere gilt: With regard to the cooling, it is furthermore particularly preferred that an inner surface of the pump chambers, in which the rotary pistons are arranged, is as large as possible. In particular:
A>400 mm2/(m3/h)*S/VR, wobei A> 400 mm 2 / (m 3 / h) * S / VR, where at
A Teil der inneren Oberfläche eines Pumpraums, der bei Enddruckbetrieb vorzugsweise einen zeitlich gemittelten Druck von über 200 mbar aufweist, A part of the inner surface of a pump chamber, which preferably has a time-averaged pressure of over 200 mbar at final pressure operation,
S das höchste gemessene Saugvermögen der Vakuumpumpe zwischen Eintrittsdrücken am Pumpeneinlass von 1-50 mbar und S is the highest measured suction capacity of the vacuum pump between inlet pressures at the pump inlet of 1-50 mbar and
VR das Volumenverhältnis ist. Um entsprechend große Oberflächen bei gegebenem Fördervolumen zu realisieren, sind moderate Drehzahlen der Rotoren vorteilhaft. Insbesondere ist die Drehzahl < 60007min, bevorzugt < 45007min, besonders bevorzugt < 30007min. VR is the volume ratio. In order to realize correspondingly large surfaces for a given delivery volume, moderate rotational speeds of the rotors are advantageous. In particular, the speed <60007min, preferably <45007min, more preferably <30007min.
Weiterhin ist bevorzugt, dass die Verbindungskanäle eine z. B. durch Rippen vergrößerte Oberfläche aufweisen, um das Gas effektiv zu kühlen. Furthermore, it is preferred that the connecting channels have a z. B. by ribs enlarged surface to effectively cool the gas.
Bei einer besonders bevorzugten Weiterbildung der Erfindung liegt bei Betreiben der mehrstufigen Wälzkolbenpumpe im Enddruck die Gastemperatur un- mittelbar nach der letzten Stufe unter 300°C, vorzugsweise unter 250°C, und besonders bevorzugt unter 200°C. Gemessen werden diese Temperaturen bei einer Umgebungstemperatur von ca. 20°C und einer Kühlmitteleintrittstemperatur von ca. 20°C, sowie bei nominellem Kühlwasserfluss (d.h. die Temperaturerhöhung des Kühlwassers ist kleiner als 20°C von Eintritt zu Austritt) und Betrieb mit Luft. In a particularly preferred development of the invention, when the multi-stage Roots pump is operated at the final pressure, the gas temperature is indirectly after the last stage below 300 ° C, preferably below 250 ° C, and more preferably below 200 ° C. These temperatures are measured at an ambient temperature of about 20 ° C and a coolant inlet temperature of about 20 ° C, and at nominal cooling water flow (ie the temperature increase of the cooling water is less than 20 ° C from inlet to outlet) and operation with air.
Desweiteren ist es bevorzugt, dass die Drehkolben und vorzugsweise auch die die Drehkolben tragenden Wellen aus einer Stahllegierung bzw. aus Stahl hergestellt sind. Insbesondere ist die Kombination aus Stahlwelle und Aluminiumgehäuse vorteilhaft, da die Wärmeausdehnungskoeffizienten deutlich unterschiedlich sind . Furthermore, it is preferred that the rotary pistons and preferably also the shafts carrying the rotary pistons are made of a steel alloy or of steel. In particular, the combination of steel shaft and aluminum housing is advantageous because the thermal expansion coefficients are significantly different.
Das Gehäuse weist vorzugsweise Aluminium oder eine Aluminiumlegierung auf. The housing preferably comprises aluminum or an aluminum alloy.
Besonders bevorzugt sind die Kombinationen der vorstehenden Merkmale, da hierdurch ein besonders gutes Saugvermögen erzielt werden kann. Particularly preferred are the combinations of the above features, as a result, a particularly good pumping speed can be achieved.
Ein weiterer wesentlicher Vorteil der erfindungsgemäßen mehrstufigen Wälzkolbenpumpe besteht darin, dass der erforderliche Bauraum deutlich reduziert werden kann. Das Vorsehen von Vorvakuumpumpen ist nicht mehr erforderlich, oder es können zumindest kleinere Vorvakuumpumpen eingesetzt werden. Another significant advantage of the multi-stage Roots pump according to the invention is that the required space can be significantly reduced. The provision of backing pumps is no longer required, or at least smaller backing pumps can be used.
Bei einer weiteren bevorzugten Ausführungsform ist der Auslass der ersten Pumpstufe mit einer Umwegleitung verbunden. In der Umwegleitung ist ein Ventil angeordnet. Die Umwegleitung ist insbesondere mit dem Einlass der ersten Pumpstufe verbunden. Durch das Vorsehen einer derartigen Umwegleitung kann eine Entlastung der ersten Stufe erfolgen. Ferner ist hierdurch sichergestellt, dass die Druckerhöhung in der ersten Pumpstufe begrenzt wird . Des weiteren ist es erfindungsgemäß möglich, den Antriebsmotor kurzzeitig über Nennleistung zu betreiben. Hierdurch kann die Effektivität der Pumpe weiter verbessert werden. Ein Antriebsmotor kann hierbei insbesondere für einen Zeitraum von 5 bis zu 30 Sekunden über der Nennleistung betrieben werden. Insbesondere ist es möglich, die Leistung um 50%, vorzugsweise um 100% gegenüber der Nennleistung zu erhöhen. In a further preferred embodiment, the outlet of the first pumping stage is connected to a bypass line. In the Umwegleitung a valve is arranged. The bypass line is connected in particular to the inlet of the first pumping stage. By providing such a detour line, a relief of the first stage can take place. Furthermore, this ensures that the pressure increase in the first pumping stage is limited. Furthermore, it is possible according to the invention to operate the drive motor for a short time over rated power. As a result, the effectiveness of the pump can be further improved. A drive motor can be operated here in particular for a period of 5 to 30 seconds above the rated power. In particular, it is possible to increase the power by 50%, preferably by 100% compared to the rated power.
Nachfolgend wird die Erfindung anhand einer bevorzugten Ausführungsform anhand der anliegenden Zeichnungen näher erläutert. The invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying drawings.
Es zeigen : Show it :
Fig. 1 eine schematische Schnittansicht einer erfindungsgemäßen mehrstufigen Wälzkolbenpumpe und Fig. 1 is a schematic sectional view of a multi-stage Roots pump according to the invention and
Fig. 2 einen schematischen Querschnitt einer Wälzkolbenstufe mit zwei Zähnen. Fig. 2 is a schematic cross section of a Wälzkolbenstufe with two teeth.
Eine erfindungsgemäße mehrstufige Wälzkolbenpumpe weist in einem Pumpengehäuse 10 mehrere Pumpstufen 12, 14, 16, 18 auf. Je Pumpstufe sind zwei Drehkolben vorgesehen. Entsprechende als zweizähnige Drehkolben ausgebildete Drehkolben 20 sind schematisch in Fig . 2 im Querschnitt dargestellt. Die beiden Drehkolben 20 drehen sich gegensinnig, so dass Gas in Richtung eines Pfeils 22 durch einen Gaseinlass 24 eingesaugt und durch einen gegenüberliegenden Auslass 26 in Richtung eines Pfeils 28 wieder ausgestoßen wird . A multi-stage Roots pump according to the invention has a plurality of pump stages 12, 14, 16, 18 in a pump housing 10. Per pump stage two rotary pistons are provided. Corresponding rotary lobe 20 designed as a bidentate rotary piston are shown schematically in FIG. 2 shown in cross section. The two rotary pistons 20 rotate in opposite directions, so that gas is sucked in the direction of an arrow 22 through a gas inlet 24 and discharged through an opposite outlet 26 in the direction of an arrow 28 again.
Je ein Drehkolben der Drehkolbenpaare ist auf einer gemeinsamen Welle 30 (Fig. 1) angeordnet. Insofern weist die mehrstufige Wälzkolbenpumpe zwei in Fig. 1 hintereinanderliegende Wellen 30 auf, die jeweils in dem Gehäuse 10 gelagert sind. Der Antrieb der Wellen erfolgt beispielsweise über Zahnräder 32. Das zu fördernde Gas wird über einen Pumpeneinlass 34 angesaugt und über einen Pumpenauslass 36 ausgestoßen. Die einzelnen Stufen 12, 14, 16 18 sind jeweils über Verbindungskanäle 38 miteinander verbunden. Dabei weist jede Pumpstufe 12, 14, 16, 18 einen Auslass 40 auf, durch den das zu fördernde Gas in den Verbindungskanal 38 gefördert wird . Der Auslass 42 der letzten Pumpstufe 18 ist mit dem Pumpenauslass 36 verbunden . Des Weiteren weisen die Pumpstufen 14, 16, 18 jeweils einen Einlass 44 auf, der jeweils mit dem entsprechenden Verbindungskanal 38 verbunden ist. An jedem Einlass 44 ist ein Ventil 46, 48, 50 bei dem es sich beispielsweise um ein gewichtsbelastetes Kugelventil handeln kann, vorgesehen. Über die Ventile kann eine Verbindung zwischen den Einlassen 44 und einem Entlastungskanal 52 erfolgen. Die erste Stufe 12 kann ferner mit einer nicht dargestellten Umwegleitung verbunden sein. Eine derartige Umwegleitung ist mit dem Auslass 40 der ersten Stufe 12 verbunden und weist ein Umwegleitungsventil auf. Die Umwegleitung ist üblicherweise mit dem Einlass 34 der ersten Stufe verbunden. Der Entlastungkanal 52 ist mit dem Pumpenauslass 36 verbunden . A respective rotary piston of the rotary piston pairs is arranged on a common shaft 30 (FIG. 1). In this respect, the multi-stage Roots pump has two successive in Fig. 1 shafts 30, which are each mounted in the housing 10. The drive of the waves takes place for example via gears 32. The gas to be delivered is sucked in via a pump inlet 34 and discharged via a pump outlet 36. The individual stages 12, 14, 16 18 are each connected via connecting channels 38 with each other. Each pumping stage 12, 14, 16, 18 has an outlet 40, through which the gas to be delivered is conveyed into the connecting channel 38. The outlet 42 of the last pumping stage 18 is connected to the pump outlet 36. Furthermore, the pumping stages 14, 16, 18 each have an inlet 44 which is in each case connected to the corresponding connecting channel 38. At each inlet 44 is a valve 46, 48, 50, which may be, for example, a weighted ball valve, is provided. Via the valves, a connection between the inlets 44 and a discharge channel 52 can take place. The first stage 12 may be further connected to a detour line, not shown. Such a bypass line is connected to the outlet 40 of the first stage 12 and has a bypass line valve. The bypass line is usually connected to the inlet 34 of the first stage. The discharge channel 52 is connected to the pump outlet 36.
Bevorzugt ist es, dass das Saugvermögen der einzelnen Pumpstufen in Förderrichtung abnimmt. Insbesondere beträgt das Saugvermögen einer nachfolgenden Pumpstufe die Hälfte des Saugvermögens der vorangegangenen Pumpstufe. It is preferred that the pumping speed of the individual pumping stages decreases in the conveying direction. In particular, the pumping speed of a subsequent pumping stage is half the pumping speed of the preceding pumping stage.
Am Pumpenauslass 36 beträgt der Druck üblicherweise ca. 1000 mbar. At the pump outlet 36, the pressure is usually about 1000 mbar.
Die Wälzkolbenpumpe kann idealisiert entsprechend der nachstehenden Tabelle betrieben werden, wenn Druckverluste in Ventilen und Leitungen vernachlässigt werden. The Roots pump can be ideally operated according to the table below, if pressure losses in valves and lines are neglected.
Die Tabelle gilt für ein Abstufungsverhältnis von 2 : 1 für jede Pumpstufe, d .h. die nachfolgende Stufe weist das halbe Saugvermögen der vorherigen Pumpstufe auf. The table applies to a 2: 1 graduation ratio for each pump stage, ie. the subsequent stage has half the pumping speed of the previous pumping stage.
Hierbei ist Pein der am Pumpeneinlass 34 herrschende Druck. Der Druck Pi ist der am Einlass der zweiten Stufe 14, P2 der am Einlass der dritten Stufe 16 und P3 der am Einlass der vierten Stufe 18 herrschende Druck. In this case, the pressure at the pump inlet 34 is insufficient. The pressure Pi is the pressure prevailing at the inlet of the second stage 14, P 2 is the pressure prevailing at the inlet of the third stage 16, and P3 is the pressure prevailing at the inlet of the fourth stage 18.
Die angegebenen Drücke verstehen sich in mbar. The stated pressures are in mbar.
Das Ventil Vi ist das Ventil 46, das Ventil V2 das Ventil 48 und das Ventil V3 das Ventil 50. "0" bedeutet, dass das Ventil geöffnet und "g", dass das Ventil geschlossen ist. The valve Vi is the valve 46, the valve V 2 is the valve 48 and the valve V3 is the valve 50. "0" means that the valve is opened and "g" that the valve is closed.
Die vorstehenden in der Tabelle genannten Werte stellen nur ein Beispiel dar. Relevant ist, dass sich die Drücke je nachdem, welche Ventile geöffnet sind, von einer zur nächsten Stufe jeweils halbieren. Eine Halbierung des Drucks erfolgt somit stets dann, wenn das entsprechende Ventil in der Stufe geschlossen ist, da die Stufe nur bei geschlossenem Ventil arbeitet. The above values listed in the table are only an example. It is relevant that the pressures halve from one stage to the next, depending on which valves are open. A halving of the pressure thus always takes place when the corresponding valve is closed in the stage, since the stage operates only when the valve is closed.

Claims

Ansprüche claims
Mehrstufige Wälzkolbenpumpe, mit zwei in einem Gehäuse (10) angeordneten, mehrere Drehkolben (20) tragenden Wellen, wobei korrespondierende Drehkolben (20) ein Drehkolbenpaar ausbilden und mehrere jeweils eine Pumpenstufe (12, 14, 16, 18) ausbildende Drehkolbenpaare vorgesehen sind, mehreren jeweils benachbarte Pumpstufen miteinander verbindenden Verbindungskanälen (38), einem mit der ersten Pumpstufe verbundenen Pumpeneinlass (34) und einem mit der letzten Pumpstufe verbundenen Pumpenauslass (36), dadurch gekennzeichnet, dass das eingebaute Volumenverhältnis (VR) mindestens 15, vorzugsweise mindestens 20 und besonders bevorzugt mindestens 25 beträgt. Multi-stage Roots pump, with two in a housing (10) arranged, a plurality of rotary piston (20) supporting waves, with corresponding rotary piston (20) form a rotary piston pair and a plurality of each pump stage (12, 14, 16, 18) forming rotary piston pairs are provided, a plurality respectively adjacent pumping stages connecting connecting channels (38), one connected to the first pumping stage pump inlet (34) and one connected to the last pump stage pump outlet (36), characterized in that the built-in volume ratio (VR) at least 15, preferably at least 20 and especially preferably at least 25.
Mehrstufige Wälzkolbenpumpe nach Anspruch 1, dadurch gekennzeichnet, dass die Anzahl (n) der Stufen mindestens drei, insbesondere mindestens fünf beträgt. Multi-stage Roots pump according to claim 1, characterized in that the number (n) of the stages is at least three, in particular at least five.
3. Mehrstufige Wälzkolbenpumpe nach Anspruch 2, dadurch gekennzeichnet, dass für die Anzahl (n) der Stufen gilt: n > /VR - I . 3. Multi-stage Roots pump according to claim 2, characterized in that for the number (n) of the stages applies: n> / VR - I.
4. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass zur Vermeidung von Überkompression zumindest eine der Pumpstufen mit einem Entlastungskanal (52) verbunden ist, in dem ein Entlastungsventil (46, 48, 50) angeordnet ist. 4. Multi-stage Roots pump according to one of claims 1 to 3, characterized in that to avoid over-compression at least one of the pumping stages is connected to a discharge channel (52) in which a relief valve (46, 48, 50) is arranged.
5. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass zumindest die zweite und dritte, insbesondere auch die vierte Pumpstufe mit einem Entlastungskanal (52) verbunden ist. 5. Multi-stage Roots pump according to one of claims 1 to 4, characterized in that at least the second and third, in particular the fourth pumping stage with a discharge channel (52) is connected.
6. Mehrstufige Wälzkolbenpumpe nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass die Entlastungskanäle (52) mit der Umgebung und/oder dem Pumpenauslass verbunden sind. 6. Multi-stage Roots pump according to claim 4 or 5, characterized in that the discharge channels (52) are connected to the environment and / or the pump outlet.
7. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Druckdifferenz benachbarter Pumpstufen kleiner als 500 mbar ist. 7. Multi-stage Roots pump according to one of claims 1 to 6, characterized in that the pressure difference of adjacent pump stages is less than 500 mbar.
8. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass das Gehäuse (10) an einer Außenseite Kühlrippen und/oder in Gehäusewänden angeordnete Kühlkanäle aufweist. 8. Multi-stage Roots pump according to one of claims 1 to 7, characterized in that the housing (10) on an outer side cooling ribs and / or arranged in housing walls has cooling channels.
9. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die Verbindungskanäle (38) im Gehäuse (10) insbesondere nahe der Kühlkanäle angeordnet sind. 9. Multi-stage Roots pump according to one of claims 1 to 8, characterized in that the connecting channels (38) in the housing (10) are arranged in particular near the cooling channels.
10. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass das Saugvermögen der gesamten Wälzkolbenpumpe mindestes 1500 m3/h, insbesondere mindestens 2500 m3/h beträgt. 10. Multi-stage Roots pump according to one of claims 1 to 9, characterized in that the pumping speed of the entire Roots pump is at least 1500 m 3 / h, in particular at least 2500 m 3 / h.
11. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, dass für eine Oberfläche (A) eines Pumpraums, in dem ein Drehkolbenpaar (20) angeordnet ist, der einen zeitlich gemittelten Druck von über 200 mbar aufweist, gilt: 11. Multi-stage Roots pump according to one of claims 1 to 10, characterized in that for a surface (A) of a pump chamber, in which a rotary piston pair (20) is arranged, which has a time-averaged pressure of over 200 mbar, the following applies:
A>400 mm2/(m3/h)*S/VR, wobei A> 400 mm 2 / (m 3 / h) * S / VR, where at
S das höchste gemessene Saugvolumen der Pumpe zwischen Enddrücken von 1-50 mbar und S is the highest measured suction volume of the pump between final pressures of 1-50 mbar and
VR das innere Volumenverhältnis ist. VR is the inner volume ratio.
12. Mehrstufige Wälzkolbenpumpe nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, dass im Enddruckbetrieb eine unmittelbar nach der letzten Stufe gemessene Gastemperatur weniger als 300°C, insbesondere weniger als 250°C und besonders bevorzugt weniger als 200°C beträgt. 12. Multi-stage Roots pump according to one of claims 1 to 11, characterized in that in the final pressure operation measured immediately after the last stage gas temperature is less than 300 ° C, in particular less than 250 ° C and more preferably less than 200 ° C.
EP18726990.7A 2017-06-17 2018-05-23 Multi-stage rotary piston pump Withdrawn EP3638906A1 (en)

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US (1) US20210140430A1 (en)
EP (1) EP3638906A1 (en)
JP (1) JP2020524236A (en)
KR (1) KR102581752B1 (en)
CN (1) CN110770444B (en)
DE (1) DE202017003212U1 (en)
TW (1) TWI770196B (en)
WO (1) WO2018228784A1 (en)

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JP2023116194A (en) * 2022-02-09 2023-08-22 株式会社荏原製作所 Vacuum pump

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CN110770444B (en) 2021-10-08
TW201907091A (en) 2019-02-16
CN110770444A (en) 2020-02-07
KR20200019620A (en) 2020-02-24
JP2020524236A (en) 2020-08-13
DE202017003212U1 (en) 2018-09-18
KR102581752B1 (en) 2023-09-21
WO2018228784A1 (en) 2018-12-20
TWI770196B (en) 2022-07-11
US20210140430A1 (en) 2021-05-13

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