EP3441617A1 - Method for heating a rotor of a vacuum pump - Google Patents

Method for heating a rotor of a vacuum pump Download PDF

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Publication number
EP3441617A1
EP3441617A1 EP17185534.9A EP17185534A EP3441617A1 EP 3441617 A1 EP3441617 A1 EP 3441617A1 EP 17185534 A EP17185534 A EP 17185534A EP 3441617 A1 EP3441617 A1 EP 3441617A1
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EP
European Patent Office
Prior art keywords
rotor
heating
electric motor
vacuum pump
temperature
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Granted
Application number
EP17185534.9A
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German (de)
French (fr)
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EP3441617B1 (en
Inventor
Tobias Stoll
Michael Schweighöfer
Martin Lohse
Jan Hofmann
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Pfeiffer Vacuum GmbH
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Pfeiffer Vacuum GmbH
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Priority to EP17185534.9A priority Critical patent/EP3441617B1/en
Priority to JP2018120626A priority patent/JP6770024B2/en
Publication of EP3441617A1 publication Critical patent/EP3441617A1/en
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Publication of EP3441617B1 publication Critical patent/EP3441617B1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/58—Cooling; Heating; Diminishing heat transfer
    • F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
    • F04D29/584—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps cooling or heating the machine

Definitions

  • the present invention relates to a method for heating a rotor of a vacuum pump, in particular a turbomolecular pump, wherein the rotor is drivable by means of an electric motor.
  • an ultra-high vacuum is present in a recipient, ie a pressure of less than 10 -10 mbar.
  • the recipient and also a flange and optionally a housing of a vacuum pump connected to the recipient must be baked to remove water molecules for reducing the residual gas pressure in the recipient from the inside surfaces of the recipient and the flange Vacuum pump to remove.
  • the rotor of a vacuum pump Due to its mounting, for example a magnetic bearing, the rotor of a vacuum pump is usually thermally insulated from corresponding stator parts of the vacuum pump and thus with respect to the pump flange and the recipient. Heating elements, which are provided for heating the recipient and the pump flange, therefore can not heat the rotor.
  • the rotor When the rotor heats up during operation of the vacuum pump, for example, in an application requiring a gas load or an increased backing pressure, the rotor will outgas due to its lack of bakeout. As a result, the pressure in the recipient rises due to the heating of the rotor. This can have the consequence that the desired final pressure in the recipient, for example a pressure in the ultra-high vacuum range, not or only with great difficulty can be achieved.
  • the rotor of the vacuum pump should therefore also be heated during the evacuation of the recipient.
  • such an approach is time consuming and therefore incurs additional costs.
  • the electromagnetic properties of the rotor are changed, for example, directly by means of a magnetic field or indirectly by a manipulation of the control of the electric motor.
  • the heating of the rotor thus requires no additional gas load, so that neither a device for the additional gas inlet is necessary, nor there is the risk of contamination by additional gas. Since the eddy currents within the rotor can be generated directly by changing the electromagnetic properties of the rotor, the temperature required for heating the rotor can be reached faster than in a method in which the heating of the rotor takes place by means of additional gas friction due to a gas load.
  • the inventive method can also be carried out simultaneously with the conventional heating of a recipient and a housing of the vacuum pump described above.
  • the simultaneous heating of the recipient and the housing as well as the rotor of the vacuum pump reduces the likelihood that molecules released from the surfaces of the rotor due to heating will re-attach to surfaces of the recipient or static parts of the vacuum pump and vice versa. As a result, a lower end pressure in the recipient can be achieved, and the time is shortened until this final pressure is reached.
  • the eddy currents are generated by an efficiency reduction of the electric motor.
  • the electric motor is temporarily operated at a reduced efficiency in driving the rotor. This contributes to a simple and cost-effective heating of the rotor, in which it requires no additional components compared to the normal operation of the vacuum pump, but only a special control of existing components.
  • the eddy currents are preferably generated by a change in the power supply for the electric motor, in particular by a change, preferably displacement, a commutation for a stator of the electric motor.
  • a change in the power supply for the electric motor in particular by a change, preferably displacement, a commutation for a stator of the electric motor.
  • One part of a commutation phase can be used, for example, to accelerate the electric motor, while in another part of the commutation phase, a deceleration of the electric motor takes place.
  • electronics for controlling the vacuum pump therefore, only a separate setting mode is required for heating the rotor, which leads to the displacement of the commutation for the stator of the electric motor compared to the normal operation of the vacuum pump. The heating of the rotor can thus be carried out with a particularly low cost.
  • the eddy currents can be generated by an external magnetic field.
  • This has the advantage that optimum control of the electric motor for driving the rotor during heating or heating of the rotor can be maintained. Furthermore, no change or expansion of the electronics for driving the vacuum pump or the electric motor for the drive is required because the external magnetic field is generated by a separate device.
  • the temperature of the rotor is measured by means of a temperature sensor and kept at the desired temperature for a predetermined period of time.
  • the temperature sensor can be ensured that the desired temperature of the rotor is actually achieved and the desired temperature for the predetermined period of time is maintained.
  • the predetermined period of time can be determined empirically, for example, on the basis of the pressure rise during the heating of the rotor.
  • the desired temperature is preferably a temperature at which outgassing of the rotor occurs, and is in particular in a range between 90 ° C and 120 ° C.
  • the desired temperature is thus a compromise between a minimum temperature at which, for example, water molecules and other impurities still separate from the rotor, and a temperature of well above 120 ° C, which would be more suitable for heating the rotor, but the operation of the rotor and thus the vacuum pump would affect overall.
  • the time period should be selected such that impairment of the operability of the vacuum pump is precluded.
  • the generation of the eddy currents for heating the rotor is stopped when a predetermined pressure at an inlet of the vacuum pump is exceeded.
  • the heating of the rotor can thus be additionally controlled by means of a measurement of the pressure in the high-vacuum or ultra-high vacuum range.
  • the predetermined pressure is then undershot when the outgassing of the rotor stops and the rotor is sufficiently baked. By stopping the heating of the rotor falls below the predetermined pressure, the generation of the eddy currents to an effective period of time limited. This can reduce the energy consumption and the cost of heating the rotor.
  • the invention further relates to a vacuum pump, in particular a turbomolecular pump having a rotor, an electric motor for driving the rotor and a control device for the electric motor, which is designed to carry out one of the methods described above.
  • Fig. 1 schematically shows an arrangement with which a method according to the invention for heating or heating a rotor of a vacuum pump can be performed.
  • this is a turbomolecular pump 11, more precisely a so-called split-flow pump, which operates between a not shown inlet and an outlet 12 of the pump has a total of six ports H1 to H6 at which the pressure can be measured and via which a gas inlet into the pump is possible.
  • ports H1 to H6 are in Fig. 1 only ports H1, H3 and H5 are shown.
  • the turbomolecular pump 11 has a turbomolecular pumping stage 13 and a Holweckpumptreatment 15 and a rotor 17 for both pumping stages 13, 15 which is drivable by means of an electric motor 19. Further, a control device 21 is provided, which includes a power supply and an electronics for controlling the electric motor 19 and is connected by means of connecting lines 23 to the electric motor 19 of the turbomolecular pump 11.
  • an ultra-high vacuum can be generated, ie a pressure in the range of less than 10 -10 mbar.
  • the turbomolecular pump 11 has, within the turbomolecular pumping stage 13, a port H1 at which the pressure in the vicinity of the inlet can be measured, and a port H3 at which the pressure in a central region of the turbomolecular pumping stage 13 can be measured. Further, the turbomolecular pump 11 within the Holweckpumpch 17 a port H5, which is intended to measure the pressure in the vicinity of the outlet of the pump and for the admission of a gas load.
  • the outlet 12 of the turbomolecular pump 11 is connected by means of a vacuum line 25 to a backing pump 27.
  • the arrangement comprises a device 29 for generating an external magnetic field.
  • a temperature sensor 28 is provided, through which the temperature of the rotor 17 can be measured and which is arranged for example on a lower part of the turbomolecular pump 11.
  • a first operating phase is provided which corresponds to a normal operation of the turbomolecular pump 11 and in which the temperature of the rotor 17 is in the range of the ambient temperature.
  • the electric motor 19 is controlled during the first phase of operation such that leakage currents, such as eddy currents, are minimized in the rotor 17.
  • a warning threshold for the signal of the temperature sensor 28 is also provided, which corresponds to a predetermined temperature of the rotor 17, above which the turbomolecular pump 11 should not be operated in the first phase of operation. Consequently, if the signal of the temperature sensor 28 during the first operating phase exceeds the warning threshold, a warning is issued to the control device 21.
  • a changed control of the electric motor 19 is provided in comparison to normal operation. Specifically, a commutation for a stator of the electric motor 19 is shifted compared to the normal operation during the second operating phase, so that eddy currents in the rotor 17 arise. These eddy currents lead to a heating of the rotor 17 and thus to outgassing the same, without an additional gas load, for example via the port H5, is admitted into the turbomolecular pump 11.
  • the warning threshold of the temperature sensor 28, ie for the temperature of the rotor 17, is further increased or deactivated in order to avoid unintentional termination of the heating and of the heating of the rotor 17.
  • the signal of the temperature sensor 28 is used in the second phase of operation not only for control purposes, but it is used to control the temperature of the rotor 17 to a desired temperature, which is for example in a range between 90 ° C and 120 ° C.
  • the temperature of the Rotor 17 may also be raised above 120 ° C for a limited, comparatively short, period of time to improve the efficiency of bakeout. Since the temperature sensor 28 is already present in the turbomolecular pump 11 anyway, the method according to the invention thus requires no additional device for regulating the temperature of the rotor 17, but merely an adaptation of the control device 21 which is likewise present.
  • the second operating phase can be ended when a predetermined pressure at an inlet of the turbomolecular pump 11 is exceeded, because the outgassing of the rotor 17 has stopped and the rotor 17 is thus sufficiently baked.
  • the turbomolecular pump 11 is then operated again under the conditions of the first operating phase described above.
  • the device 29 generates an external magnetic field in the region of the rotor 17, which also generates eddy currents in the rotor 17.
  • the rotor 17 can also be heated and baked by means of the external magnetic field generating device 29.
  • Turbomolekularpumpe 11 admitted that at the outlet 12 each had approximately the same pressure as the upper curves 31 and 41 in Fig. 2 or 3 show.
  • the increased pressure due to the additional gas led to an increased gas friction in the rotor 17 and thereby to its heating, which in turn a degassing of the rotor 17 was triggered.
  • Fig. 2 and 3 is the pressure at various positions of a vacuum system, such as schematically in Fig. 1 is illustrated over time.
  • the pressure measurement was carried out in each case at the outlet 12 of the turbomolecular pump 11, ie in the fore-vacuum region (curves 31 and 41), at the port H5 (cf. Fig. 1 , Curve 42 in Fig. 3 ), at port H3 (curves 33 and 43), at port H1 (curves 35 and 45) and at the inlet of the turbomolecular pump 11, ie in the ultra-high vacuum range (curves 37, 39, 47 and 49).
  • the pressure measurement in the ultra-high vacuum range was carried out at two different positions in the region of the inlet of the turbomolecular pump 11.
  • the pressure in the ultra-high vacuum region of the assembly increased due to the outgassing of the previously not heated rotor 17 of about 10 -10 mbar to almost 10 -9 mbar, ie by about one order of magnitude. Further, operation over several hours with additional gas load was required until the ultra high vacuum pressure of the assembly did not increase and a saturation pressure was reached. Besides, it was even after several hours the operation with additional gas load no further drop in pressure to observe, which would have indicated a reduction in the outgassing of the rotor 17.
  • the test result of Fig. 3 shows thus that the rotor 17 was efficiently heated and baked by the method according to the invention and the pressure increase in the ultra-high vacuum despite additional gas load in Vorvakuum Society was at least an order of magnitude lower than without previous heating of the rotor 17.
  • the curves 47 and 49 of Fig. 3 in that the rotor 17 was able to sufficiently outgas beforehand by the method according to the invention, so that even with additional gas load and the resulting additional heating of the rotor 17 in comparison with the curves 37 and 39 of FIG Fig. 2 only a slight increase in pressure occurred in the ultra-high vacuum range.
  • the successful heating of the rotor 17 by means of the method according to the invention can also be recognized from the fact that the pressure increase in the curves 47 and 49 of FIG Fig. 3 after a short time reached the saturation value below 10 -10 mbar.

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

Abstract

Es ist ein Verfahren zum Erwärmen eines Rotors einer Vakuumpumpe, insbesondere einer Turbomolekularpumpe, vorgesehen. Die Vakuumpumpe weist einen mittels eines Elektromotors antreibbaren Rotor auf, dessen Temperatur während einer ersten Betriebsphase der Vakuumpumpe im Bereich einer Umgebungstemperatur liegt. Gemäß dem Verfahren werden während einer zweiten Betriebsphase Wirbelströme innerhalb des Rotors erzeugt, die eine Erwärmung des Rotors auf eine gewünschte Temperatur oberhalb der Umgebungstemperatur bewirken.A method is provided for heating a rotor of a vacuum pump, in particular a turbomolecular pump. The vacuum pump has a rotor drivable by means of an electric motor, the temperature of which is in the range of an ambient temperature during a first operating phase of the vacuum pump. According to the method, eddy currents are generated within the rotor during a second operating phase, which cause heating of the rotor to a desired temperature above the ambient temperature.

Description

Die vorliegende Erfindung betrifft ein Verfahren zum Erwärmen eines Rotors einer Vakuumpumpe, insbesondere einer Turbomolekularpumpe, wobei der Rotor mittels eines Elektromotors antreibbar ist.The present invention relates to a method for heating a rotor of a vacuum pump, in particular a turbomolecular pump, wherein the rotor is drivable by means of an electric motor.

Bei manchen wissenschaftlichen Untersuchungen und Herstellungsverfahren, beispielsweise in der Halbleitertechnik, ist es erforderlich, dass in einem Rezipienten ein Ultrahochvakuum vorliegt, d.h. ein Druck kleiner als 10-10 mbar. Um einen solchen Druck im Rezipienten zu erreichen, müssen der Rezipient und auch ein Flansch sowie gegebenenfalls ein Gehäuse einer Vakuumpumpe, die mit dem Rezipienten verbunden ist, ausgeheizt werden, um Wassermoleküle zur Verringerung des Restgasdrucks im Rezipienten von den Innenflächen des Rezipienten und des Flansches der Vakuumpumpe zu entfernen.In some scientific studies and manufacturing processes, for example in semiconductor technology, it is necessary that an ultra-high vacuum is present in a recipient, ie a pressure of less than 10 -10 mbar. In order to achieve such a pressure in the recipient, the recipient and also a flange and optionally a housing of a vacuum pump connected to the recipient must be baked to remove water molecules for reducing the residual gas pressure in the recipient from the inside surfaces of the recipient and the flange Vacuum pump to remove.

Der Rotor einer Vakuumpumpe ist aufgrund seiner Lagerung, beispielsweise einer Magnetlagerung, üblicherweise gegenüber entsprechenden Statorteilen der Vakuumpumpe und somit gegenüber dem Pumpenflansch und dem Rezipienten thermisch isoliert. Heizelemente, die zum Ausheizen des Rezipienten und des Pumpenflansches vorgesehen sind, können den Rotor folglich nicht ausheizen.Due to its mounting, for example a magnetic bearing, the rotor of a vacuum pump is usually thermally insulated from corresponding stator parts of the vacuum pump and thus with respect to the pump flange and the recipient. Heating elements, which are provided for heating the recipient and the pump flange, therefore can not heat the rotor.

Wenn sich der Rotor währen des Betriebs der Vakuumpumpe erwärmt, beispielsweise bei einer Anwendung, die eine Gaslast oder einen erhöhten Vorvakuumdruck erfordert, gast der Rotor aufgrund seines fehlenden Ausheizens aus. Dadurch steigt der Druck im Rezipienten aufgrund der Erwärmung des Rotors an. Dies kann zur Folge haben, dass der gewünschte Enddruck im Rezipienten, beispielsweise ein Druck im Ultrahochvakuumbereich, nicht oder nur sehr schwer erreicht werden kann.When the rotor heats up during operation of the vacuum pump, for example, in an application requiring a gas load or an increased backing pressure, the rotor will outgas due to its lack of bakeout. As a result, the pressure in the recipient rises due to the heating of the rotor. This can have the consequence that the desired final pressure in the recipient, for example a pressure in the ultra-high vacuum range, not or only with great difficulty can be achieved.

Der Rotor der Vakuumpumpe sollte bei der Evakuierung des Rezipienten somit ebenfalls ausgeheizt werden. Zu diesem Zweck wurde vorgeschlagen, die Gasreibung innerhalb des Rotors zu erhöhen, indem entweder der Vorvakuumdruck erhöht wird oder eine zusätzliche Gaslast in der Nähe des Auslasses der Vakuumpumpe vorgesehen wird. Aufgrund der erhöhten Gasreibung steigt die Temperatur des Rotors, wodurch dieser ausgeheizt wird. Eine solche Vorgehensweise ist jedoch zeitintensiv und daher mit zusätzlichen Kosten verbunden.The rotor of the vacuum pump should therefore also be heated during the evacuation of the recipient. For this purpose, it has been proposed to increase the gas friction within the rotor by either increasing the fore-vacuum pressure or providing an additional gas load near the outlet of the vacuum pump. Due to the increased gas friction, the temperature of the rotor increases, causing it to heat up. However, such an approach is time consuming and therefore incurs additional costs.

Aufgrund des begrenzten Saugvermögens der Vakuumpumpe erfolgt darüber hinaus beim Einlassen von zusätzlichem Gas am Auslass der Vakuumpumpe eine unvermeidbare Rückströmung in Richtung ihres Einlasses und in den Rezipienten hinein. Moleküle des eingelassenen Gases können sich daher zusätzlich an den Innenflächen des Rezipienten anlagern. Dadurch kann sich der maximal realisierbare Enddruck im Rezipienten derart erhöhen, dass der Ultrahochvakuumbereich möglicherweise nicht mehr erreicht wird. Zumindest wird durch den zusätzlichen Gaseinlass die Zeit verlängert, bis ein akzeptabler Enddruck im Rezipienten erreicht ist. Ferner ist das Einlassen von zusätzlichem Gas in den Hochvakuum- bzw. Ultrahochvakuumbereich einer Vakuumanlage insofern problematisch, als über das zusätzliche Gas Verunreinigungen in den Rezipienten gelangen können.In addition, due to the limited pumping speed of the vacuum pump, when additional gas is admitted at the outlet of the vacuum pump, an unavoidable backflow takes place in the direction of its inlet and into the recipient. Molecules of the admitted gas can therefore additionally accumulate on the inner surfaces of the recipient. As a result, the maximum realizable end pressure in the recipient can increase in such a way that the ultra-high vacuum region may no longer be reached. At least, the additional gas inlet increases the time until an acceptable final pressure in the recipient is achieved. Furthermore, the admission of additional gas in the high vacuum or ultra-high vacuum range of a vacuum system is problematic insofar as impurities can enter the recipient via the additional gas.

Daher besteht eine Aufgabe der Erfindung darin, ein Verfahren zum Erwärmen eines Rotors einer Vakuumpumpe zu schaffen, mit welchem der Rotor auf eine zum Ausheizen ausreichende Temperatur erwärmt werden kann, ohne dass zusätzliches Gas in die Vakuumanlage eingebracht werden muss.Therefore, it is an object of the invention to provide a method for heating a rotor of a vacuum pump, with which the rotor can be heated to a temperature sufficient for heating, without additional gas must be introduced into the vacuum system.

Diese Aufgabe wird durch ein Verfahren mit den Merkmalen des Anspruchs 1 gelöst und insbesondere dadurch, dass innerhalb des Rotors einer Vakuumpumpe, der mittels eines Elektromotors antreibbar ist und dessen Temperatur während einer ersten Betriebsphase der Vakuumpumpe im Bereich einer Umgebungstemperatur liegt, während einer zweiten Betriebsphase Wirbelströme erzeugt werden, die eine Erwärmung des Rotors auf eine gewünschte Temperatur oberhalb der Umgebungstemperatur bewirken.This object is achieved by a method having the features of claim 1 and in particular by virtue of the fact that, within the rotor of a vacuum pump, which is drivable by means of an electric motor and whose temperature during a first operating phase of the vacuum pump is in the range of an ambient temperature, during a second operating phase eddy currents are generated, which cause heating of the rotor to a desired temperature above ambient temperature.

Zur Erzeugung der Wirbelströme werden die elektromagnetischen Eigenschaften des Rotors verändert, beispielsweise direkt mittels eines Magnetfelds oder indirekt durch eine Manipulation der Ansteuerung des Elektromotors. Die Erwärmung des Rotors erfordert somit keine zusätzliche Gaslast, so dass weder eine Vorrichtung für den zusätzlichen Gaseinlass notwendig ist, noch die Gefahr einer Verunreinigung durch zusätzliches Gas besteht. Da die Wirbelströme innerhalb des Rotors durch Veränderung der elektromagnetischen Eigenschaften des Rotors auf unmittelbare Weise erzeugt werden können, lässt sich die zum Ausheizen des Rotors erforderliche Temperatur schneller erreichen als bei einem Verfahren, bei welchem die Erwärmung des Rotors mittels zusätzlicher Gasreibung aufgrund einer Gaslast erfolgt.To generate the eddy currents, the electromagnetic properties of the rotor are changed, for example, directly by means of a magnetic field or indirectly by a manipulation of the control of the electric motor. The heating of the rotor thus requires no additional gas load, so that neither a device for the additional gas inlet is necessary, nor there is the risk of contamination by additional gas. Since the eddy currents within the rotor can be generated directly by changing the electromagnetic properties of the rotor, the temperature required for heating the rotor can be reached faster than in a method in which the heating of the rotor takes place by means of additional gas friction due to a gas load.

Das erfindungsgemäße Verfahren kann ferner gleichzeitig mit dem eingangs beschriebenen herkömmlichen Ausheizen eines Rezipienten und eines Gehäuses der Vakuumpumpe ausgeführt werden. Durch das gleichzeitige Ausheizen des Rezipienten und des Gehäuses sowie des Rotors der Vakuumpumpe wird die Wahrscheinlichkeit verringert, dass sich Moleküle, die sich aufgrund der Erwärmung von den Oberflächen des Rotors lösen, wieder an Oberflächen des Rezipienten oder von statischen Teilen der Vakuumpumpe anlagern und umgekehrt. Dadurch ist ein geringerer Enddruck im Rezipienten erreichbar, und es wird die Zeit verkürzt, bis dieser Enddruck erreicht ist.The inventive method can also be carried out simultaneously with the conventional heating of a recipient and a housing of the vacuum pump described above. The simultaneous heating of the recipient and the housing as well as the rotor of the vacuum pump reduces the likelihood that molecules released from the surfaces of the rotor due to heating will re-attach to surfaces of the recipient or static parts of the vacuum pump and vice versa. As a result, a lower end pressure in the recipient can be achieved, and the time is shortened until this final pressure is reached.

Vorteilhafte Ausführungsformen der Erfindung sind in den Unteransprüchen, der Beschreibung und in den Figuren angegeben.Advantageous embodiments of the invention are set forth in the subclaims, the description and in the figures.

Gemäß einer Ausführungsform werden die Wirbelströme durch eine Effizienzreduzierung des Elektromotors erzeugt. Im Vergleich zu einem Normalbetrieb, bei dem Wirbelstromverluste im Rotor unerwünscht sind, wird der Elektromotor beim Antreiben des Rotors vorübergehend mit einem verringerten Wirkungsgrad betrieben. Dies trägt zu einer einfachen und kostengünstigen Erwärmung des Rotors bei, in dem es im Vergleich zum Normalbetrieb der Vakuumpumpe keine zusätzlichen Komponenten erfordert, sondern lediglich eine spezielle Ansteuerung vorhandener Komponenten.According to one embodiment, the eddy currents are generated by an efficiency reduction of the electric motor. Compared to a normal operation in which eddy current losses in the rotor are undesirable, the electric motor is temporarily operated at a reduced efficiency in driving the rotor. This contributes to a simple and cost-effective heating of the rotor, in which it requires no additional components compared to the normal operation of the vacuum pump, but only a special control of existing components.

Die Wirbelströme werden bevorzugt durch eine Veränderung der Stromzufuhr für den Elektromotor erzeugt, und zwar insbesondere durch eine Veränderung, bevorzugt Verschiebung, einer Kommutierung für einen Stator des Elektromotors. Ein Teil einer Kommutierungsphase kann beispielsweise zum Beschleunigen des Elektromotors genutzt werden, während in einem anderen Teil der Kommutierungsphase ein Abbremsen des Elektromotors erfolgt. In einer Elektronik zur Ansteuerung der Vakuumpumpe ist für das Erwärmen des Rotors folglich lediglich ein gesonderter Einstellungsmodus erforderlich, der im Vergleich zum Normalbetrieb der Vakuumpumpe zur Verschiebung der Kommutierung für den Stator des Elektromotors führt. Das Erwärmen des Rotors kann folglich mit einem besonders geringen Aufwand ausgeführt werden.The eddy currents are preferably generated by a change in the power supply for the electric motor, in particular by a change, preferably displacement, a commutation for a stator of the electric motor. One part of a commutation phase can be used, for example, to accelerate the electric motor, while in another part of the commutation phase, a deceleration of the electric motor takes place. In electronics for controlling the vacuum pump, therefore, only a separate setting mode is required for heating the rotor, which leads to the displacement of the commutation for the stator of the electric motor compared to the normal operation of the vacuum pump. The heating of the rotor can thus be carried out with a particularly low cost.

Alternativ oder zusätzlich können die Wirbelströme durch ein externes Magnetfeld erzeugt werden. Dies hat den Vorteil, dass eine optimale Ansteuerung des Elektromotors zum Antreiben des Rotors während des Erwärmens bzw. Ausheizens des Rotors beibehalten werden kann. Ferner ist keine Veränderung bzw. Erweiterung der Elektronik zum Ansteuern der Vakuumpumpe bzw. des Elektromotors für deren Antrieb erforderlich, da das externe Magnetfeld durch eine separate Vorrichtung erzeugt wird.Alternatively or additionally, the eddy currents can be generated by an external magnetic field. This has the advantage that optimum control of the electric motor for driving the rotor during heating or heating of the rotor can be maintained. Furthermore, no change or expansion of the electronics for driving the vacuum pump or the electric motor for the drive is required because the external magnetic field is generated by a separate device.

Vorteilhafterweise wird die Temperatur des Rotors mittels eines Temperatursensors gemessen und für eine vorbestimmte Zeitspanne auf der gewünschten Temperatur gehalten. Mittels des Temperatursensors kann sichergestellt werden, dass die gewünschte Temperatur des Rotors tatsächlich erreicht wird und die gewünschte Temperatur für die vorbestimmte Zeitspanne beibehalten wird. Die vorbestimmte Zeitspanne kann beispielsweise anhand des Druckanstiegs während der Erwärmung des Rotors empirisch ermittelt werden.Advantageously, the temperature of the rotor is measured by means of a temperature sensor and kept at the desired temperature for a predetermined period of time. By means of the temperature sensor can be ensured that the desired temperature of the rotor is actually achieved and the desired temperature for the predetermined period of time is maintained. The predetermined period of time can be determined empirically, for example, on the basis of the pressure rise during the heating of the rotor.

Die gewünschte Temperatur ist bevorzugt eine Temperatur, bei welcher ein Ausgasen des Rotors erfolgt, und liegt insbesondere in einem Bereich zwischen 90°C und 120°C. Die gewünschte Temperatur ist somit ein Kompromiss zwischen einer minimalen Temperatur, bei welcher sich beispielsweise Wassermoleküle und andere Verunreinigungen noch vom Rotor lösen, und einer Temperatur von deutlich oberhalb 120°C, welche zum Ausheizen des Rotors geeigneter wäre, aber den Betrieb des Rotors und somit der Vakuumpumpe insgesamt beeinträchtigen würde. Grundsätzlich ist es jedoch auch denkbar, die Temperatur des Rotors für eine begrenzte, vergleichsweise kurze, Zeitdauer über 120°C zu erhöhen. Dadurch kann die Wirksamkeit des Ausheizens verbessert werden. Die Zeitdauer sollte jedoch derart gewählt sein, dass eine Beeinträchtigung der Betriebsfähigkeit der Vakuumpumpe ausgeschlossen ist.The desired temperature is preferably a temperature at which outgassing of the rotor occurs, and is in particular in a range between 90 ° C and 120 ° C. The desired temperature is thus a compromise between a minimum temperature at which, for example, water molecules and other impurities still separate from the rotor, and a temperature of well above 120 ° C, which would be more suitable for heating the rotor, but the operation of the rotor and thus the vacuum pump would affect overall. In principle, however, it is also conceivable to increase the temperature of the rotor for a limited, comparatively short, period of time above 120.degree. This can improve the effectiveness of bakeout. However, the time period should be selected such that impairment of the operability of the vacuum pump is precluded.

Gemäß einer weiteren Ausführungsform wird das Erzeugen der Wirbelströme zum Erwärmen des Rotors beendet, wenn ein vorbestimmter Druck an einem Einlass der Vakuumpumpe unterschritten wird. Das Ausheizen des Rotors kann somit zusätzlich mittels einer Messung des Drucks im Hochvakuum- bzw. Ultrahochvakuumbereich gesteuert werden. Der vorbestimmte Druck wird dann unterschritten, wenn das Ausgasen des Rotors aufhört und der Rotor ausreichend ausgeheizt ist. Durch das Beenden des Ausheizens des Rotors bei Unterschreiten des vorbestimmten Drucks wird das Erzeugen der Wirbelströme auf einen wirksamen Zeitraum begrenzt. Dadurch können der Energieverbrauch und die Kosten für das Ausheizen des Rotors verringert werden.According to a further embodiment, the generation of the eddy currents for heating the rotor is stopped when a predetermined pressure at an inlet of the vacuum pump is exceeded. The heating of the rotor can thus be additionally controlled by means of a measurement of the pressure in the high-vacuum or ultra-high vacuum range. The predetermined pressure is then undershot when the outgassing of the rotor stops and the rotor is sufficiently baked. By stopping the heating of the rotor falls below the predetermined pressure, the generation of the eddy currents to an effective period of time limited. This can reduce the energy consumption and the cost of heating the rotor.

Die Erfindung betrifft ferner eine Vakuumpumpe, insbesondere eine Turbomolekularpumpe, die einen Rotor, einen Elektromotor zum Antreiben des Rotors und eine Steuereinrichtung für den Elektromotor aufweist, welche dazu ausgebildet ist, eines der vorstehend beschriebenen Verfahren auszuführen.The invention further relates to a vacuum pump, in particular a turbomolecular pump having a rotor, an electric motor for driving the rotor and a control device for the electric motor, which is designed to carry out one of the methods described above.

Die Erfindung wird nachfolgend rein beispielhaft anhand möglicher Ausführungsformen der Erfindung unter Bezugnahme auf die beigefügten Figuren erläutert. Es zeigen:

Fig. 1
eine schematische Darstellung einer Anordnung zum erfindungsgemäßen Erwärmen eines Rotors einer Vakuumpumpe,
Fig. 2
zeitliche Verläufe des Drucks an verschiedenen Positionen einer Vakuumanlage, bei welcher ein Rotor einer Vakuumpumpe nicht mit dem erfindungsgemäßen Verfahren erwärmt wurde, und
Fig. 3
zeitliche Verläufe des Drucks an verschiedenen Positionen einer Vakuumanlage, bei welcher der Rotor der Vakuumpumpe zuvor mit dem erfindungsgemäßen Verfahren erwärmt wurde.
The invention is explained below purely by way of example with reference to possible embodiments of the invention with reference to the accompanying figures. Show it:
Fig. 1
a schematic representation of an arrangement for heating according to the invention of a rotor of a vacuum pump,
Fig. 2
time profiles of the pressure at various positions of a vacuum system in which a rotor of a vacuum pump has not been heated by the method according to the invention, and
Fig. 3
time profiles of the pressure at various positions of a vacuum system, in which the rotor of the vacuum pump was previously heated by the method according to the invention.

Fig. 1 zeigt schematisch eine Anordnung, mit der ein erfindungsgemäßes Verfahren zum Erwärmen bzw. Ausheizen eines Rotors einer Vakuumpumpe ausgeführt werden kann. Bei der Vakuumpumpe handelt es sich hier um eine Turbomolekularpumpe 11, genauer gesagt um eine sogenannte Splitflow-Pumpe, die zwischen einem nicht dargestellten Einlass und einem Auslass 12 der Pumpe insgesamt sechs Ports H1 bis H6 aufweist, an denen der Druck gemessen werden kann und über die ein Gaseinlass in die Pumpe hinein möglich ist. Von diesen Ports H1 bis H6 sind in Fig. 1 nur die Ports H1, H3 und H5 dargestellt. Fig. 1 schematically shows an arrangement with which a method according to the invention for heating or heating a rotor of a vacuum pump can be performed. In the case of the vacuum pump, this is a turbomolecular pump 11, more precisely a so-called split-flow pump, which operates between a not shown inlet and an outlet 12 of the pump has a total of six ports H1 to H6 at which the pressure can be measured and via which a gas inlet into the pump is possible. Of these ports H1 to H6 are in Fig. 1 only ports H1, H3 and H5 are shown.

Die Turbomolekularpumpe 11 weist eine Turbomolekularpumpstufe 13 und eine Holweckpumpstufe 15 sowie einen Rotor 17 für beide Pumpstufen 13, 15 auf, der mittels eines Elektromotors 19 antreibbar ist. Ferner ist eine Steuereinrichtung 21 vorgesehen, die eine Stromversorgung und eine Elektronik zum Steuern des Elektromotors 19 beinhaltet und mittels Verbindungsleitungen 23 mit dem Elektromotor 19 der Turbomolekularpumpe 11 verbunden ist.The turbomolecular pump 11 has a turbomolecular pumping stage 13 and a Holweckpumpstufe 15 and a rotor 17 for both pumping stages 13, 15 which is drivable by means of an electric motor 19. Further, a control device 21 is provided, which includes a power supply and an electronics for controlling the electric motor 19 and is connected by means of connecting lines 23 to the electric motor 19 of the turbomolecular pump 11.

Am Einlass der Turbomolekularpumpe 11 kann ein Ultrahochvakuum erzeugt werden, d.h. ein Druck im Bereich kleiner 10-10 mbar. Die Turbomolekularpumpe 11 weist innerhalb der Turbomolekularpumpstufe 13 einen Port H1, an welchem der Druck in der Nähe des Einlasses gemessen werden kann, und einen Port H3 auf, an welchem der Druck in einem mittleren Bereich der Turbomolekularpumpstufe 13 gemessen werden kann. Ferner weist die Turbomolekularpumpe 11 innerhalb der Holweckpumpstufe 17 einen Port H5 auf, der zur Messung des Drucks in der Nähe des Auslasses der Pumpe und für das Einlassen einer Gaslast vorgesehen ist.At the inlet of the turbomolecular pump 11, an ultra-high vacuum can be generated, ie a pressure in the range of less than 10 -10 mbar. The turbomolecular pump 11 has, within the turbomolecular pumping stage 13, a port H1 at which the pressure in the vicinity of the inlet can be measured, and a port H3 at which the pressure in a central region of the turbomolecular pumping stage 13 can be measured. Further, the turbomolecular pump 11 within the Holweckpumpstufe 17 a port H5, which is intended to measure the pressure in the vicinity of the outlet of the pump and for the admission of a gas load.

Der Auslass 12 der Turbomolekularpumpe 11 ist mittels einer Vakuumleitung 25 mit einer Vorvakuumpumpe 27 verbunden.The outlet 12 of the turbomolecular pump 11 is connected by means of a vacuum line 25 to a backing pump 27.

Ferner umfasst die Anordnung eine Vorrichtung 29 zur Erzeugung eines externen Magnetfelds. Außerdem ist ein Temperatursensor 28 vorgesehen, durch den die Temperatur des Rotors 17 gemessen werden kann und der beispielsweise an einem Unterteil der Turbomolekularpumpe 11 angeordnet ist.Furthermore, the arrangement comprises a device 29 for generating an external magnetic field. In addition, a temperature sensor 28 is provided, through which the temperature of the rotor 17 can be measured and which is arranged for example on a lower part of the turbomolecular pump 11.

Für den Betrieb der Anordnung ist eine erste Betriebsphase vorgesehen, die einem Normalbetrieb der Turbomolekularpumpe 11 entspricht und in der die Temperatur des Rotors 17 im Bereich der Umgebungstemperatur liegt. Der Elektromotor 19 wird während der ersten Betriebsphase derart angesteuert, dass Verlustströme, wie beispielsweise Wirbelströme, im Rotor 17 minimiert sind.For the operation of the arrangement, a first operating phase is provided which corresponds to a normal operation of the turbomolecular pump 11 and in which the temperature of the rotor 17 is in the range of the ambient temperature. The electric motor 19 is controlled during the first phase of operation such that leakage currents, such as eddy currents, are minimized in the rotor 17.

Für die erste Betriebsphase ist ferner eine Warnschwelle für das Signal des Temperatursensors 28 vorgesehen, welche einer vorbestimmten Temperatur des Rotors 17 entspricht, oberhalb derer die Turbomolekularpumpe 11 in der ersten Betriebsphase nicht betrieben werden sollte. Wenn das Signal des Temperatursensors 28 während der ersten Betriebsphase die Warnschwelle überschreitet, wird folglich eine Warnung an der Steuereinrichtung 21 ausgegeben.For the first operating phase, a warning threshold for the signal of the temperature sensor 28 is also provided, which corresponds to a predetermined temperature of the rotor 17, above which the turbomolecular pump 11 should not be operated in the first phase of operation. Consequently, if the signal of the temperature sensor 28 during the first operating phase exceeds the warning threshold, a warning is issued to the control device 21.

Während einer zweiten Betriebsphase der Turbomolekularpumpe 11, die auch als "Ausheizphase" bezeichnet werden kann, ist hingegen eine veränderte Ansteuerung des Elektromotors 19 im Vergleich zum Normalbetrieb vorgesehen. Konkret ist während der zweiten Betriebsphase eine Kommutierung für einen Stator des Elektromotors 19 im Vergleich zum Normalbetrieb verschoben, so dass Wirbelströme im Rotor 17 entstehen. Diese Wirbelströme führen zu einer Erwärmung des Rotors 17 und somit zu einem Ausgasen desselben, ohne dass eine zusätzliche Gaslast, beispielsweise über den Port H5, in die Turbomolekularpumpe 11 eingelassen wird.During a second operating phase of the turbomolecular pump 11, which may also be referred to as a "bake-out phase", a changed control of the electric motor 19 is provided in comparison to normal operation. Specifically, a commutation for a stator of the electric motor 19 is shifted compared to the normal operation during the second operating phase, so that eddy currents in the rotor 17 arise. These eddy currents lead to a heating of the rotor 17 and thus to outgassing the same, without an additional gas load, for example via the port H5, is admitted into the turbomolecular pump 11.

Während der zweiten Betriebsphase wird ferner die Warnschwelle des Temperatursensors 28, d.h. für die Temperatur des Rotors 17, erhöht oder deaktiviert, um einen unbeabsichtigten Abbruch der Erwärmung und des Ausheizen des Rotors 17 zu vermeiden. Das Signal des Temperatursensors 28 wird in der zweiten Betriebsphase nicht nur zu Kontrollzwecken verwendet, sondern es dient zur Regelung der Temperatur des Rotors 17 auf eine gewünschte Temperatur, die beispielsweise in einem Bereich zwischen 90°C und 120°C liegt. Die Temperatur des Rotors 17 kann ferner für eine begrenzte, vergleichsweise kurze, Zeitdauer über 120°C erhöht werden, um die Wirksamkeit des Ausheizens zu verbessern. Da der Temperatursensor 28 in der Turbomolekularpumpe 11 ohnehin schon vorhanden ist, benötigt das erfindungsgemäße Verfahren somit keine zusätzliche Vorrichtung zur Regelung der Temperatur des Rotors 17, sondern lediglich eine Anpassung der ebenfalls vorhandenen Steuereinrichtung 21.During the second operating phase, the warning threshold of the temperature sensor 28, ie for the temperature of the rotor 17, is further increased or deactivated in order to avoid unintentional termination of the heating and of the heating of the rotor 17. The signal of the temperature sensor 28 is used in the second phase of operation not only for control purposes, but it is used to control the temperature of the rotor 17 to a desired temperature, which is for example in a range between 90 ° C and 120 ° C. The temperature of the Rotor 17 may also be raised above 120 ° C for a limited, comparatively short, period of time to improve the efficiency of bakeout. Since the temperature sensor 28 is already present in the turbomolecular pump 11 anyway, the method according to the invention thus requires no additional device for regulating the temperature of the rotor 17, but merely an adaptation of the control device 21 which is likewise present.

Die zweite Betriebsphase kann beendet werden, wenn ein vorbestimmter Druck an einem Einlass der Turbomolekularpumpe 11 unterschritten wird, weil das Ausgasen des Rotors 17 aufhört hat und der Rotor 17 somit ausreichend ausgeheizt ist. Die Turbomolekularpumpe 11 wird anschließend wieder unter den Bedingungen der vorstehend beschriebenen ersten Betriebsphase betrieben.The second operating phase can be ended when a predetermined pressure at an inlet of the turbomolecular pump 11 is exceeded, because the outgassing of the rotor 17 has stopped and the rotor 17 is thus sufficiently baked. The turbomolecular pump 11 is then operated again under the conditions of the first operating phase described above.

Alternativ oder zusätzlich zur Veränderung der Kommutierung des Elektromotors 19 erzeugt die Vorrichtung 29 ein externes Magnetfeld im Bereich des Rotors 17, welches ebenso Wirbelströme im Rotor 17 erzeugt. Somit kann der Rotor 17 auch mittels der Vorrichtung 29 zur Erzeugung des externen Magnetfelds erwärmt und ausgeheizt werden.Alternatively, or in addition to changing the commutation of the electric motor 19, the device 29 generates an external magnetic field in the region of the rotor 17, which also generates eddy currents in the rotor 17. Thus, the rotor 17 can also be heated and baked by means of the external magnetic field generating device 29.

Um das Ausheizen des Rotors der Turbomolekularpumpe 11 mittels des erfindungsgemäßen Verfahrens unter Verwendung der Anordnung von Fig. 1 zu demonstrieren, wurden Druckmessungen an der Turbomolekularpumpe 11 mit zwei unterschiedlichen Vorbedingungen durchgeführt. Die Ergebnisse der Druckmessungen sind in Fig. 2 und 3 dargestellt. Bei den Kurven von Fig. 2 wurde der Rotor 17 der Turbomolekularpumpe 11 zuvor nicht erwärmt bzw. ausgeheizt, während bei den Kurven von Fig. 3 zuvor das erfindungsgemäße Verfahren zum Erwärmen und Ausheizen des Rotors 17 verwendet wurde.In order to heat the rotor of the turbomolecular pump 11 by means of the method according to the invention using the arrangement of Fig. 1 To demonstrate, pressure measurements were made on the turbomolecular pump 11 with two different preconditions. The results of the pressure measurements are in Fig. 2 and 3 shown. At the curves of Fig. 2 was the rotor 17 of the turbomolecular pump 11 previously not heated or annealed, while in the curves of Fig. 3 previously the inventive method for heating and heating of the rotor 17 was used.

Ferner wurde zu Testzwecken sowohl bei den Druckmessungen von Fig. 2 als auch bei denjenigen von Fig. 3 derart ein Gas im Bereich den Auslasses 12 derFurthermore, for test purposes both the pressure measurements of Fig. 2 as well as those of Fig. 3 such a gas in the area of the outlet 12 of the

Turbomolekularpumpe 11 eingelassen, dass am Auslass 12 jeweils ungefähr der gleiche Druck vorlag, wie dies die oberen Kurven 31 und 41 in Fig. 2 bzw. 3 zeigen. Der erhöhte Druck aufgrund des zusätzlichen Gases führte zu einer erhöhten Gasreibung im Rotor 17 und dadurch zu dessen Erwärmung, wodurch wiederum ein Ausgasen des Rotors 17 ausgelöst wurde.Turbomolekularpumpe 11 admitted that at the outlet 12 each had approximately the same pressure as the upper curves 31 and 41 in Fig. 2 or 3 show. The increased pressure due to the additional gas led to an increased gas friction in the rotor 17 and thereby to its heating, which in turn a degassing of the rotor 17 was triggered.

In Fig. 2 und 3 ist der Druck an verschiedenen Positionen einer Vakuumanlage, wie sie beispielsweise schematisch in Fig. 1 veranschaulicht ist, über der Zeit dargestellt. Die Druckmessung erfolgte jeweils am Auslass 12 der Turbomolekularpumpe 11, d.h. im Vorvakuumbereich (Kurven 31 und 41), am Port H5 (vgl. Fig. 1, Kurve 42 in Fig. 3), am Port H3 (Kurven 33 und 43), am Port H1 (Kurven 35 und 45) sowie am Einlass der Turbomolekularpumpe 11, d.h. im Ultrahochvakuumbereich (Kurven 37, 39, 47 und 49). Zur Verbesserung der Messsicherheit wurde die Druckmessung im Ultrahochvakuumbereich an zwei unterschiedlichen Positionen im Bereich des Einlasses der Turbomolekularpumpe 11 durchgeführt.In Fig. 2 and 3 is the pressure at various positions of a vacuum system, such as schematically in Fig. 1 is illustrated over time. The pressure measurement was carried out in each case at the outlet 12 of the turbomolecular pump 11, ie in the fore-vacuum region (curves 31 and 41), at the port H5 (cf. Fig. 1 , Curve 42 in Fig. 3 ), at port H3 (curves 33 and 43), at port H1 (curves 35 and 45) and at the inlet of the turbomolecular pump 11, ie in the ultra-high vacuum range (curves 37, 39, 47 and 49). To improve the measurement reliability, the pressure measurement in the ultra-high vacuum range was carried out at two different positions in the region of the inlet of the turbomolecular pump 11.

Sowohl bei der Druckmessung von Fig. 2 als auch bei der Druckmessung von Fig. 3 wurde der Druck im Vorvakuumbereich der Anordnung im Vergleich zum Normalbetrieb durch Einlassen eines Gases mittels des Ports H5 auf etwa 3 mbar erhöht (vgl. die Kurven 31 bzw. 41 in Fig. 2 bzw. 3). Dadurch trat ein Druckanstieg an den Ports H3 und H1 sowie auch im Ultrahochvakuumbereich am Einlass der Turbomolekularpumpe 11 auf. Der Druckanstieg ist am deutlichsten in Fig. 2 im zeitlichen Verlauf der Kurven 31, 33 und 35 zu erkennen.Both in the pressure measurement of Fig. 2 as well as in the pressure measurement of Fig. 3 For example, the pressure in the pre-vacuum region of the assembly was increased to about 3 mbar by introducing a gas via port H5 as compared to normal operation (see curves 31 and 41 in FIG Fig. 2 or 3). As a result, an increase in pressure occurred at the ports H3 and H1 as well as in the ultra-high vacuum region at the inlet of the turbomolecular pump 11. The pressure increase is most evident in Fig. 2 in the time course of the curves 31, 33 and 35 can be seen.

Wie ferner in Fig. 2 zu erkennen ist, stieg der Druck im Ultrahochvakuumbereich der Anordnung aufgrund des Ausgasens des zuvor nicht ausgeheizten Rotors 17 von etwa 10-10 mbar auf nahezu 10-9 mbar an, d.h. um etwa eine Größenordnung. Ferner war ein Betrieb über mehrere Stunden mit zusätzlicher Gaslast erforderlich, bis der Druck im Ultrahochvakuumbereich der Anordnung nicht mehr anstieg und ein Sättigungsdruck erreicht wurde. Außerdem war sogar nach mehreren Stunden des Betriebs mit zusätzlicher Gaslast kein erneuter Abfall des Drucks zu beobachten, welcher auf eine Verringerung des Ausgasens des Rotors 17 hingedeutet hätte.As further in Fig. 2 can be seen, the pressure in the ultra-high vacuum region of the assembly increased due to the outgassing of the previously not heated rotor 17 of about 10 -10 mbar to almost 10 -9 mbar, ie by about one order of magnitude. Further, operation over several hours with additional gas load was required until the ultra high vacuum pressure of the assembly did not increase and a saturation pressure was reached. Besides, it was even after several hours the operation with additional gas load no further drop in pressure to observe, which would have indicated a reduction in the outgassing of the rotor 17.

Wenn der Rotor 17 der Turbomolekularpumpe 11 jedoch zuvor mittels des erfindungsgemäßen Verfahrens erwärmt und ausgeheizt wurde (siehe Fig. 3), trat zwar im Betrieb mit zusätzlicher Gaslast zunächst ebenfalls ein Druckanstieg im Ultrahochvakuumbereich der Anordnung auf, der jedoch nach erheblich kürzerer Zeit einen Sättigungswert erreichte, welcher noch dazu deutlich unterhalb von 10-10 mbar lag (vgl. die Kurven 47 und 49 in Fig. 3). Selbst mit einer zusätzlichen Gaslast im Vorvakuumbereich der Anordnung lag der Druck im Rezipienten somit immer noch im gewünschten Ultrahochvakuumbereich. Dabei resultiert ein vergleichsweise geringer Druckanstieg in den Kurven 47 und 49 vor allem aus einer unvermeidlichen Rückströmung des zusätzlich eingelassenen Gases in Richtung des Einlasses der Turbomolekularpumpe 11, d.h. in den Ultrahochvakuumbereich hinein, und weniger aus einem Ausgasen des Rotors 17.However, when the rotor 17 of the turbomolecular pump 11 has previously been heated and baked by the method according to the invention (see Fig. 3 ), although in operation with additional gas load initially likewise an increase in pressure in the ultra-high vacuum region of the arrangement occurred, but after a much shorter time reached a saturation value, which was still well below 10 -10 mbar (see the curves 47 and 49 in Fig. 3 ). Even with an additional gas load in the pre-vacuum region of the arrangement, the pressure in the recipient was thus still within the desired ultra-high vacuum range. In this case, a comparatively small rise in pressure in the curves 47 and 49 results above all from an unavoidable backflow of the additionally admitted gas in the direction of the inlet of the turbomolecular pump 11, ie into the ultra-high vacuum range, and less from outgassing of the rotor 17.

Das Testergebnis von Fig. 3 zeigt somit, dass der Rotor 17 mittels des erfindungsgemäßen Verfahrens effizient erwärmt und ausgeheizt wurde und der Druckanstieg im Ultrahochvakuumbereich trotz zusätzlicher Gaslast im Vorvakuumbereich um mindestens eine Größenordnung geringer war als ohne vorheriges Ausheizen des Rotors 17. Mit anderen Worten zeigen die Kurven 47 und 49 von Fig. 3, dass der Rotor 17 zuvor durch das erfindungsgemäße Verfahren ausreichend ausgasen konnte, so dass selbst mit zusätzlicher Gaslast und daraus resultierender zusätzlicher Erwärmung des Rotors 17 im Vergleich zu den Kurven 37 und 39 von Fig. 2 nur ein geringer Druckanstieg im Ultrahochvakuumbereich auftrat. Das erfolgreiche Ausheizen des Rotors 17 mittels des erfindungsgemäßen Verfahrens ist auch daran zu erkennen, dass der Druckanstieg in den Kurven 47 und 49 von Fig. 3 schon nach kurzer Zeit den Sättigungswert unterhalb von 10-10 mbar erreichte.The test result of Fig. 3 shows thus that the rotor 17 was efficiently heated and baked by the method according to the invention and the pressure increase in the ultra-high vacuum despite additional gas load in Vorvakuumbereich was at least an order of magnitude lower than without previous heating of the rotor 17. In other words, the curves 47 and 49 of Fig. 3 in that the rotor 17 was able to sufficiently outgas beforehand by the method according to the invention, so that even with additional gas load and the resulting additional heating of the rotor 17 in comparison with the curves 37 and 39 of FIG Fig. 2 only a slight increase in pressure occurred in the ultra-high vacuum range. The successful heating of the rotor 17 by means of the method according to the invention can also be recognized from the fact that the pressure increase in the curves 47 and 49 of FIG Fig. 3 after a short time reached the saturation value below 10 -10 mbar.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

1111
TurbomolekularpumpeTurbo molecular pump
1212
Auslassoutlet
1313
TurbomolekularpumpstufeTurbo molecular pump stage
1515
HolweckpumpstufeHolweckpumpstufe
1717
Rotorrotor
1919
Elektromotorelectric motor
2121
Steuereinrichtungcontrol device
2323
Verbindungsleitungeninterconnectors
2525
Vakuumleitungvacuum line
2727
Vorvakuumpumpebacking pump
2828
Temperatursensortemperature sensor
2929
Vorrichtung zur Erzeugung eines externen MagnetfeldsDevice for generating an external magnetic field
H1H1
Port im Bereich des PumpeneinlassesPort in the area of the pump inlet
H3H3
Port im mittleren Bereich der TurbomolekularpumpstufePort in the middle area of the turbomolecular pumping stage
H5H5
Port im Bereich der HolweckpumpstufePort in the area of Holweckpumpstufe
31,4131.41
Vorvakuumdruckbacking pressure
4242
Druck am Port H5Pressure at port H5
33, 4333, 43
Druck am Port H3Pressure at port H3
35,4535.45
Druck am Port H1Pressure at port H1
37, 47, 39, 4937, 47, 39, 49
Druck im UltrahochvakuumbereichPressure in the ultra-high vacuum range

Claims (10)

Verfahren zum Erwärmen eines Rotors (17) einer Vakuumpumpe (11), insbesondere einer Turbomolekularpumpe (11), welche einen mittels eines Elektromotors (19) antreibbaren Rotor (17) aufweist, dessen Temperatur während einer ersten Betriebsphase der Vakuumpumpe (11) im Bereich einer Umgebungstemperatur liegt,
dadurch gekennzeichnet, dass
während einer zweiten Betriebsphase Wirbelströme innerhalb des Rotors (17) erzeugt werden, die eine Erwärmung des Rotors (17) auf eine gewünschte Temperatur oberhalb der Umgebungstemperatur bewirken.Method for heating a rotor (17) of a vacuum pump (11), in particular a turbomolecular pump (11), which has a rotor (17) which can be driven by means of an electric motor (19) whose temperature is within the range of a first operating phase of the vacuum pump (11) Ambient temperature is,
characterized in that
during a second phase of operation eddy currents are generated within the rotor (17), which cause a heating of the rotor (17) to a desired temperature above the ambient temperature. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
die Wirbelströme durch eine Effizienzreduzierung des Elektromotors (19) erzeugt werden.Method according to claim 1,
characterized in that
the eddy currents are generated by an efficiency reduction of the electric motor (19). Verfahren nach Anspruch 1 oder 2,
die Wirbelströme durch eine Veränderung der Stromzufuhr zu dem Elektromotor (19) erzeugt werden.Method according to claim 1 or 2,
the eddy currents are generated by a change in the power supply to the electric motor (19). Verfahren nach Anspruch 3,
dadurch gekennzeichnet, dass
die Wirbelströme durch eine Veränderung, insbesondere Verschiebung, einer Kommutierung für einen Stator des Elektromotors (19) erzeugt werden.Method according to claim 3,
characterized in that
the eddy currents are generated by a change, in particular displacement, of a commutation for a stator of the electric motor (19). Verfahren nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet, dass
die Wirbelströme durch ein externes Magnetfeld erzeugt werden.Method according to one of the preceding claims,
characterized in that
the eddy currents are generated by an external magnetic field. Verfahren nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet, dass
die Temperatur des Rotors (17) mittels eines Temperatursensors (28) gemessen und für eine vorbestimmte Zeitspanne auf der gewünschten Temperatur gehalten wird.Method according to one of the preceding claims,
characterized in that
the temperature of the rotor (17) is measured by means of a temperature sensor (28) and maintained at the desired temperature for a predetermined period of time. Verfahren nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet, dass
die gewünschte Temperatur eine Temperatur ist, bei welcher ein Ausgasen des Rotors (17) erfolgt.Method according to one of the preceding claims,
characterized in that
the desired temperature is a temperature at which outgassing of the rotor (17) occurs. Verfahren nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet, dass
die gewünschte Temperatur in einem Bereich zwischen 90°C und 120°C liegt.Method according to one of the preceding claims,
characterized in that
the desired temperature is in a range between 90 ° C and 120 ° C. Verfahren nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet, dass
das Erzeugen der Wirbelströme zum Erwärmen des Rotors (17) beendet wird, wenn ein vorbestimmter Druck an einem Einlass der Vakuumpumpe (11) unterschritten wird.Method according to one of the preceding claims,
characterized in that
the generation of the eddy currents for heating the rotor (17) is stopped when a predetermined pressure at an inlet of the vacuum pump (11) is exceeded. Vakuumpumpe (11), insbesondere Turbomolekularpumpe (11), mit: einem Rotor (17), einem Elektromotor (19) zum Antreiben des Rotors (17) und einer Steuereinrichtung (21) für den Elektromotor (19), welche dazu ausgebildet ist, ein Verfahren nach einem der vorstehenden Ansprüche auszuführen. Vacuum pump (11), in particular turbomolecular pump (11), with: a rotor (17), an electric motor (19) for driving the rotor (17) and a control device (21) for the electric motor (19), which is designed to carry out a method according to one of the preceding claims.
EP17185534.9A 2017-08-09 2017-08-09 Method for heating a rotor of a vacuum pump Active EP3441617B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP17185534.9A EP3441617B1 (en) 2017-08-09 2017-08-09 Method for heating a rotor of a vacuum pump
JP2018120626A JP6770024B2 (en) 2017-08-09 2018-06-26 How to heat the rotor of a vacuum pump

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP17185534.9A EP3441617B1 (en) 2017-08-09 2017-08-09 Method for heating a rotor of a vacuum pump

Publications (2)

Publication Number Publication Date
EP3441617A1 true EP3441617A1 (en) 2019-02-13
EP3441617B1 EP3441617B1 (en) 2019-12-25

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ID=59579485

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EP17185534.9A Active EP3441617B1 (en) 2017-08-09 2017-08-09 Method for heating a rotor of a vacuum pump

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JP (1) JP6770024B2 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2023000891A (en) 2021-06-18 2023-01-04 エドワーズ株式会社 Vacuum pump
EP3926174B1 (en) * 2021-06-29 2023-06-14 Pfeiffer Vacuum Technology AG Vacuum pump

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2313175A (en) * 1941-03-20 1943-03-09 Carbide & Carbon Chem Corp Vacuum distillation process and apparatus
DE3216404A1 (en) * 1982-05-03 1983-11-10 Arthur Pfeiffer Vakuumtechnik Wetzlar Gmbh, 6334 Asslar HEATING FOR A TURBO MOLECULAR PUMP
JPH04112996A (en) * 1990-08-30 1992-04-14 Shimadzu Corp Turbo molecular pump
EP3112688A1 (en) * 2015-07-01 2017-01-04 Pfeiffer Vacuum GmbH Split flow vacuum pump and vacuum system with a split flow vacuum pump

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6508631B1 (en) * 1999-11-18 2003-01-21 Mks Instruments, Inc. Radial flow turbomolecular vacuum pump
JP2002285992A (en) * 2001-03-27 2002-10-03 Boc Edwards Technologies Ltd Vacuum pump
JP2013079602A (en) * 2011-10-04 2013-05-02 Shimadzu Corp Turbo-molecular pump

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2313175A (en) * 1941-03-20 1943-03-09 Carbide & Carbon Chem Corp Vacuum distillation process and apparatus
DE3216404A1 (en) * 1982-05-03 1983-11-10 Arthur Pfeiffer Vakuumtechnik Wetzlar Gmbh, 6334 Asslar HEATING FOR A TURBO MOLECULAR PUMP
JPH04112996A (en) * 1990-08-30 1992-04-14 Shimadzu Corp Turbo molecular pump
EP3112688A1 (en) * 2015-07-01 2017-01-04 Pfeiffer Vacuum GmbH Split flow vacuum pump and vacuum system with a split flow vacuum pump

Also Published As

Publication number Publication date
JP6770024B2 (en) 2020-10-14
JP2019031969A (en) 2019-02-28
EP3441617B1 (en) 2019-12-25

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