EP3499039B1 - Screw vacuum pump - Google Patents

Screw vacuum pump Download PDF

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Publication number
EP3499039B1
EP3499039B1 EP17207576.4A EP17207576A EP3499039B1 EP 3499039 B1 EP3499039 B1 EP 3499039B1 EP 17207576 A EP17207576 A EP 17207576A EP 3499039 B1 EP3499039 B1 EP 3499039B1
Authority
EP
European Patent Office
Prior art keywords
screw
vacuum pump
pump
accordance
screw vacuum
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.)
Active
Application number
EP17207576.4A
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German (de)
French (fr)
Other versions
EP3499039A1 (en
Inventor
Peter Huber
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.)
Pfeiffer Vacuum GmbH
Original Assignee
Pfeiffer Vacuum 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 Pfeiffer Vacuum GmbH filed Critical Pfeiffer Vacuum GmbH
Priority to EP17207576.4A priority Critical patent/EP3499039B1/en
Priority to JP2018232381A priority patent/JP7221672B2/en
Publication of EP3499039A1 publication Critical patent/EP3499039A1/en
Application granted granted Critical
Publication of EP3499039B1 publication Critical patent/EP3499039B1/en
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C25/00Adaptations of pumps for special use of pumps for elastic fluids
    • F04C25/02Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08Rotary-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
    • F04C18/12Rotary-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
    • F04C18/14Rotary-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
    • F04C18/16Rotary-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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C29/00Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • F04C29/04Heating; Cooling; Heat insulation
    • F04C29/045Heating; Cooling; Heat insulation of the electric motor in hermetic pumps
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00Components
    • F04C2240/40Electric motor
    • F04C2240/403Electric motor with inverter for speed control

Definitions

  • the present invention relates to a screw vacuum pump with a housing, two screw rotors arranged in the housing and engaging with one another which, for conveying a process gas in cooperation with the housing, repeatedly form closed conveying volumes of the process gas and convey them in the direction of an outlet.
  • the vacuum performance of screw vacuum pumps is to a large extent dependent on the size and number of gaps in the active pumping area, in particular between screw rotors that are in engagement and between a respective screw rotor and an enclosing housing wall. These gaps change during operation or in comparison to standstill due to heat-dependent changes in shape, in particular expansion, of the components involved.
  • By controlling the generation of heat and limiting or reducing high temperatures in the screw pump the influence of the temperature on gaps and thus on the vacuum performance of the screw pump can be improved.
  • heat basically corresponds to losses, so that a reduction in heat production can improve the efficiency of the screw vacuum pump.
  • a screw vacuum pump according to the preamble of claim 1 disclose DE 197 45 615 A1 , the DE 197 45 616 A1 and the DE 101 56 179 A1 .
  • a screw vacuum pump with a housing, two screw rotors arranged in the housing and engaging with one another, which repeatedly form closed delivery volumes of the process gas in cooperation with the housing for delivering a process gas and deliver in the direction of an outlet, the screw vacuum pump at least one of the features described below.
  • a motor can be provided which is designed as a direct drive for one of the screw rotors. Since the motor is designed as a direct drive, there is no need to provide a coupling between the motor and the relevant screw rotor. Since a clutch generally generates heat during operation, a heat source is completely avoided. In addition, the corresponding mechanical losses in the coupling are avoided, which improves the energy efficiency of the pump.
  • Active liquid cooling can be provided.
  • the term “active cooling” relates to externally operated cooling, that is to say in particular liquid cooling with a pump.
  • a separate pump can be provided or a water pressure that is already provided on a house connection can be used.
  • the active cooling can include water cooling. The active cooling ensures rapid heat dissipation and thus helps to limit the temperatures in the screw pump
  • Active liquid cooling can be provided both for the screw rotors and for the motor.
  • the temperatures are limited both in the area of the motor and in the area of the screw rotors, i.e. on Locations in the pump where particularly high levels of heat are expected.
  • the term “for” encompasses both active cooling in the area of the element in question, that is to say, for example, in the area of the screw rotors or the motor, as well as an implementation directly in the element in question.
  • active liquid cooling can be provided in or on the housing for the screw rotors in an area, in particular an axial area, in which the screw rotors are arranged.
  • a single active liquid cooling system can be provided both for the motor and for the screw rotors, or several active liquid cooling systems can also be provided.
  • the directly driven screw rotor forms a rotor of the motor. This means that no additional storage is required for a screw rotor, which further reduces mechanical losses and corresponding heat production.
  • the motor can be designed, for example, as a permanent magnet synchronous machine, in particular with internal magnets or as an IPMSM. In this way, the efficiency can be increased further, especially since a particularly high degree of efficiency can be achieved with an IPMSM.
  • an, in particular external, frequency converter is provided for the motor.
  • this also helps to reduce mechanical losses.
  • no transmission gear has to be provided between the motor and the relevant screw rotor. Since a transmission gear always generates heat during operation, another heat source is completely avoided.
  • the corresponding mechanical losses in the transmission gear are avoided, as a result of which the energy efficiency of the pump is further improved.
  • a synchronization gear can be provided between the screw rotors, for example.
  • the screw rotors each have at least two adjacent sections along the screw axis, the screw rotors each having an at least substantially constant or increasing gradient in a first section closer to an inlet and a lower gradient than in a second section in the first section, and wherein, with respect to the screw axis, the first section is longer than a closed delivery volume in the first section, in particular longer than 360 ° or one revolution of the screw profile.
  • a gap length between a compressing area and an inlet of the pump is increased, as a result of which the corresponding sealing effect is improved.
  • the pump can thus be made more efficient.
  • a necessary processing quality of a closing surface for the screw rotors in the inlet area can be reduced as a result. This reduces the manufacturing cost of the pump.
  • a pressure relief valve is provided in the area of an internal compression of the pump, which is connected to an outlet of the pump or forms an outlet.
  • the pressure in this area which is in any case not useful, can be released if it exceeds the pressure prevailing at the outlet, that is to say usually atmospheric pressure.
  • the internal compression is thus limited to atmospheric pressure, which makes the drive power necessary for further compression unnecessary and accordingly avoids further compression heat. This leads to a decrease in temperature.
  • the pump can have a control device which is designed and / or set up to operate the pump at least in a normal operating mode at a rotor speed of approximately 120 Hz or less, in particular of approximately 120 Hz or less and of approximately 80 Hz or more .
  • a control device which is designed and / or set up to operate the pump at least in a normal operating mode at a rotor speed of approximately 120 Hz or less, in particular of approximately 120 Hz or less and of approximately 80 Hz or more .
  • a control device which is designed and / or set up to operate the pump at least in a normal operating mode at a rotor speed of approximately 120 Hz or less, in particular of approximately 120 Hz or less and of approximately 80 Hz or more .
  • the rotor and housing temperature as well as the outlet gas temperature are kept low.
  • control device is designed and / or set up to operate the pump temporarily at least in a boost operating mode in which the rotor speed is higher than in the normal operating mode.
  • boost operating mode in which the rotor speed is higher than in the normal operating mode.
  • the power can then be selectively increased if necessary, while, however, the low power consumption or the low heat production continues to be maintained in the normal operating mode.
  • An overall efficient pump is thus made available, which can, however, be used flexibly.
  • This embodiment is, for example, particularly advantageous for use with, in particular frequently, repeated evacuation, since here power can be switched on as required at the beginning of the evacuation, with the power consumption and heat production remaining relatively low on average.
  • a small motor can be sufficient to operate the screw vacuum pump.
  • a further development is characterized in that a contactless seal, in particular a piston ring, is provided for at least one of the screw rotors.
  • a lubricant discharge device for example a deflector, particularly adjacent to a seal, may be provided.
  • This can support a seal for a screw rotor in that a particularly large part of the lubricant, e.g. oil, does not even reach the seal, but is drained away beforehand. In particular, this can improve the sealing effect of a contactless seal.
  • the screw rotors can be coupled, for example, via a synchronization gear, the synchronization gear having straight teeth. When engaged, this has a small contact area, in particular in comparison to helical teeth. The heat production in the area of engagement of an appropriately designed gear is correspondingly low.
  • the pump is designed in such a way that at least one heat source, such as, for example, an internal compression, a motor or a gearbox, is arranged in the vicinity of at least one heat sink, such as, for example, a liquid cooling system. This ensures particularly effective heat dissipation.
  • at least one heat source such as, for example, an internal compression, a motor or a gearbox
  • the pump is designed in such a way that a shield is arranged between at least one heat source and at least one heat-sensitive area, for example a heat-sensitive component and / or an oil-lubricated area.
  • the shield is formed by a waist of the housing.
  • the waist limits a possible heat flow and thus ensures effective insulation. At the same time, a waist can be easily produced and, in particular, no additional insulation is necessary.
  • the waist acts to a certain extent as a heat collection point for the active cooling, so that the heat essentially does not or hardly passes through the waist, but is largely supplied to the active cooling.
  • the shield can in particular be provided between an outlet and a bearing section for the screw rotors.
  • a lubricant provided in the bearing section can be protected from high heat input from the outlet area, since lubricants are often temperature-sensitive or are more expensive to purchase for higher temperatures.
  • the shield can also be designed as insulation, for example as an insulation layer, in particular with a poorly thermally conductive material, for example a foamed material or a gas such as air.
  • a bearing section in particular a bearing plate, can be designed as a sandwich component, in particular with an insulation layer.
  • the liquid cooling is designed in such a way that it forms a turbulent flow in the area of a heat source. This ensures particularly good heat transfer in this area.
  • it can be advantageous to have a small volume, that is to say in particular Provide a small line cross-section and / or a small total amount of liquid for a cooling circuit and / or a high flow rate of the cooling fluid. This allows particularly good heat transfer, in particular due to the formation of turbulent flow conditions. Turbulence can also be generated, for example, by local narrowing of a cooling line or by abrupt changes in its inner surfaces.
  • cooling lines for active cooling can comprise aluminum or another material of high thermal conductivity, can be formed in a cast aluminum body and / or can be formed as cooling lines, in particular, pressed into housing grooves. Cooling lines are arranged in particular close to a heat source and / or follow their contour at the smallest possible distance.
  • cooling circuits can also be divided up and / or suitably connected to cool different heat sources.
  • a section of the cooling circuit can be provided completely for a particularly warm or heat-sensitive area, in particular a particularly warm or heat-sensitive component, while, for example, other sections of the cooling circuit for other areas or components that are less sensitive or produce less heat, in Can be connected in series.
  • heat sources in the pump in a group, adjacent and / or close to one another.
  • local cooling can be sufficient to cool several heat sources together. Heat generated in a concentrated manner can be dissipated particularly well.
  • the outlet in particular represents a heat source itself.
  • the heat can be dissipated particularly effectively locally here.
  • an immersion cooler can be provided, which in particular comprises aluminum.
  • the immersion cooler can be arranged, for example, in a bath of a lubricant of the vacuum pump, in particular a synchronization gear, in particular an oil bath.
  • a lubricant of the vacuum pump in particular a synchronization gear, in particular an oil bath.
  • the temperature of a sensitive lubricant can be controlled particularly well or local cooling can be provided in this temperature-sensitive area, while other areas may have to be cooled less strongly.
  • the screw rotors of the screw vacuum pump can in particular be formed by a cycloid profile or have such a profile and / or be designed with two threads.
  • a screw pitch of the screw rotors can, for example, be constant in sections, i.e. the pitch changes along a screw axis only in transition areas between the sections, with one transition area being in particular smaller than one section, in particular all transition areas being smaller than all sections.
  • an outlet of the pump can be directed downwards.
  • an inlet of the pump can be directed upwards.
  • the screw vacuum pump can, for example, have an internal compression with a compression ratio of less than 5 to 1, in particular less than 4 to 1, in particular less than 3.5 to 1, and / or greater than 2 to 1, in particular greater than 3 to 1.
  • a respective screw profile can, for example, simultaneously form or convey more than 7, in particular more than 10, in particular more than 12, in particular 13 closed conveying volumes.
  • a respective screw rotor can in particular have a ratio of the length of its screw profile to its Have a diameter of at least 2.0, in particular at least 2.5, in particular at least 3.0 and / or at most 5.0, in particular at most 4.0.
  • a vacuum chamber is evacuated repeatedly, in particular frequently, in particular several times a day, in particular several times an hour, in particular a Roots pump connected upstream of the screw pump is provided, wherein in particular the Roots pump has a pumping speed which is at most three times, in particular at most or approximately twice, as great as a pumping speed of the screw vacuum pump.
  • the aforementioned advantageous pumping speed ratio and / or a low compression ratio means that only a low compression output is applied must and only a small amount of compression heat is generated, which is easy to dissipate. This enables particularly efficient operation of the vacuum system.
  • a vacuum chamber is operated essentially permanently at a final pressure, in particular a Roots pump connected upstream of the screw pump being provided, the Roots pump in particular having a pumping speed which is at least five times, in particular at least seven times, as great as a pumping speed of the screw vacuum pump.
  • a screw vacuum pump 10 which has a motor 12, a gear box 14, a housing 16, a bearing plate 18 and a cover 20.
  • the screw vacuum pump 10 conveys a process gas from an inlet 22 to a downwardly directed, in Fig. 3 visible outlet 24.
  • Active liquid cooling which emerges from a housing of the motor 12, is provided for the motor 12.
  • active liquid cooling is also provided, which has two cooling lines which are shown in FIG Fig. 1 are not shown, but their course is indicated by corresponding grooves 32 of the housing 16 into which the cooling lines are pressed.
  • active liquid cooling systems are provided in the gear box 14 and in the cover 20 and are each designed here as an immersion cooler 34, which are shown below with reference to FIG Fig. 5 are explained in more detail.
  • the housing 16 of the screw vacuum pump 10 has a waist 36.
  • the waist 36 is arranged in the area of the outlet 24.
  • Fig. 4 the screw vacuum pump 10 is shown in a sectional view, the sectional plane of the line AA in FIG Fig. 3 corresponds to.
  • Two screw rotors 28 and 30 are visible, each having two-thread, interlocking screw profiles 38 and 40, which are generated with the aid of a cycloid profile and have a cylindrical envelope contour and a cylindrical basic shape of the screw base.
  • the screw profiles 38 and 40 in cooperation with the housing 16, form an active pumping area of the screw vacuum pump 10 and repeatedly convey closed volumes of the process gas from the inlet 22 to the outlet 24, in Fig. 4 so from left to right.
  • the pumping power of the screw vacuum pump 10 depends on the size and shape of various gaps in the active pumping area, which are unavoidable due to the relative movement of rotors 28, 30 and housing 16, but must be kept small and as constant as possible for the purpose of good pumping power. Changes in temperature in the components involved lead to their shape change. The measures described herein for avoiding, dissipating and generally controlling heat in the pump 10 thus result in the smallest possible change in shape and consequently the most manageable gaps possible. The gaps can therefore be designed more precisely, which improves the pump performance and its efficiency.
  • the screw rotor 28 is driven directly by the motor 12, that is to say without an interposed coupling.
  • the screw rotor 30, is driven via a synchronization gear 42 with gears 43 in a defined angular relationship to the screw rotor 28.
  • the motor 12 comprises a housing 44, which is made, for example, of aluminum and in which cooling lines 26 are formed for active liquid cooling.
  • the motor 12 also comprises a wound stator 46 which, together with a magnet carrier 48 attached to a shaft end of the screw rotor 28, forms an electric motor and a direct drive for the screw rotor 28.
  • the screw rotor 28 forms a rotor of the motor 12.
  • the magnet carrier 48 comprises a plurality of permanent magnets.
  • the motor 12 thus forms a permanent magnet synchronous machine with internal magnets, which is also referred to as IPMSM.
  • the stator 46 is arranged in a potting body 50, which insulates electrical conductors (not shown in greater detail) at the stator 46 and leads them to a circuit board 52 in an insulated manner.
  • the potting body 50 forms here, in conjunction with the circuit board 52, a vacuum-tight connection of the motor 12 to a connection which is atmospheric in an area Control electronics provided for pressure.
  • an external frequency converter can be provided for the motor 12.
  • at least part of an electronic control system for the motor 12 can be provided on the circuit board 52.
  • the synchronization gear 42 is arranged in the gear box 14.
  • oil is also provided as a lubricant, which is distributed by splash disks 54 via the synchronization gear 42 and adjacent bearings 56.
  • the waist 36 forms a shield or a thermal barrier, in particular for heat that is produced in the area of the screw rotors 28, 30 during the pumping operation. Because a small material cross-section remains, and because a heat path is lengthened as a result of the change in shape, the heat from the screw rotor, which otherwise spreads in the housing 16, is prevented from reaching the areas on the other side. In particular, the oil in the gear box 14 and the bearings 56 are protected from excessively high temperatures.
  • the immersion cooler 34 arranged in the gear box 14 also contributes to the temperature reduction. This is arranged in an oil bath, not shown, of the gear box 14 and thus cools the oil directly.
  • a lubricant discharge device designed as a deflector 58 is provided adjacent to the bearings 56, which here form a fixed bearing.
  • a respective deflector 58 forms a barrier for the oil in the gear box so that it does not get into a pump-active area or a vacuum area, here in particular an outlet area.
  • the deflector 58 comprises a throw-off edge, not shown in detail, for the oil. Opposite the throwing-off edge, a drainage groove is formed in the housing 16, which takes up thrown-off oil and returns it in the gear box 14 or in an oil bath there. The oil, which is conveyed or distributed by the splash disks 54 to the gears 42 and bearings 56, is thus carried away again from the rotors 28 and 30 by the deflectors 58.
  • Piston rings are provided on a piston ring carrier 60 as a dynamic fluid seal. These form a contactless seal and thus avoid frictional heat.
  • the deflectors 58 return as much oil as possible to the gear box 14 so that as little oil as possible is already present on the piston rings. In this way, an overall reliable sealing effect is achieved with particularly low heat production.
  • the screw rotors 28 and 30 have three sections of different pitch in their respective screw profile 38 and 40, respectively.
  • the first section 62 is longer in relation to a screw axis 63, which runs along a respective rotor 28 or 30, than a closed delivery volume in the first section.
  • a second section 64 has a plurality of subsections, which are not referenced in any more detail, with different but constant slopes in the screw profile 38 or 40, the slopes being lower than in the first section.
  • the second section 64 here forms the longest section.
  • a third section 66 with an even lower slope forms an ejection section. In the third section there is again a constant slope.
  • the reduced slope along the pumping direction brings about an internal compression that compresses the process gas even before it is ejected.
  • the rotors 28, 30 or the screw profiles 38, 40 can be designed and manufactured particularly easily by providing the constant sections. How it is based on Fig. 4 As can be seen, an elongated first section 62 leads to correspondingly elongated gaps between the screw profiles 28, 30 and the Housing 16, so that the path or the gap from the inner compression at the transition of the sections 62 and 64 to a suction chamber or suction area 67 is longer. The sealing effect of the gaps is correspondingly increased, which leads to an improved sealing of the inner compression with respect to the suction area 67, particularly at high differential pressures.
  • the screw vacuum pump 10 thus has an internal compression.
  • the size of a delivery volume is determined by a cross section of a screw profile 38, 40 and its pitch.
  • the size of a delivery volume on the inlet side or in section 62 determines a theoretical pumping speed of the screw pump 10.
  • the slope of the screw profile 38, 40 is constant on the inlet side over section 62 so that the delivery volume is only compressed after completion by the internal compression. If a respective rotor 28, 30 closes a respective delivery volume too early or too late or the internal compression begins too early, the theoretical pumping speed of the pump drops.
  • the size of a respective delivery volume on the outlet side or in section 66 determines the power consumption of the pump during operation at an achievable final pressure.
  • the ratio of the sizes of the delivery volume on the inlet side and outlet side or in sections 62 and 66 corresponds to the ratio of the internal compression of the pump.
  • section 66 the slope is constant over several revolutions of the screw profile 38, 40.
  • the slope corresponds approximately to the minimum of the slope that can be achieved by a specific machining tool and is therefore, in particular under cost consideration, due to manufacturing technology. Because several revolutions, that is to say several closed delivery volumes, are provided in section 66, a backflow due to a pressure difference between the gaps is compensated for.
  • the entire gradient along the rotors 28, 30 and the size of the gaps formed between the rotors 28, 30 and between rotors 28, 30 and the housing 16 determine the vacuum performance data of the pump, i.e. in particular the pumping speed and an achievable final pressure.
  • the screw profiles 38, 40 have a particularly low imbalance due to their two-thread design. For example, no compensation elements, such as compensation weights, which require additional installation space, and / or compensation bores in which material can be deposited are necessary.
  • the pump can be operated with the double-thread cycloid screw profiles 38, 40 in a wide speed range, in particular with speed control, and / or, for example, in a stand-by mode.
  • the compression of the process gas generally generates heat which, in the case of the screw pump 10, is primarily dissipated by a liquid cooling system.
  • a liquid cooling system In Fig. 4 the grooves 32 provided for this purpose are visible. Cooling lines of the liquid cooling extend here and preferably in the longitudinal direction over a wide area of the screw profiles, in particular over at least half the length of the screw profiles. In particular, the liquid cooling is arranged in the area or in the vicinity of an internal compression.
  • the end shield 18 is attached to an inlet-side end of the housing 16. This carries, among other things, a further bearing with bearings 68, which form a floating bearing.
  • a further bearing with bearings 68 which form a floating bearing.
  • the bearing plate 68 is formed as a separate component, but can also be formed integrally.
  • injection disks 54, deflectors 58 and a piston ring carrier 60 with a plurality of piston rings are also provided, which operate in accordance with the arrangement on the outlet side.
  • a further, separately designed oil bath is provided in the cover 20.
  • An immersion cooler 34 is also provided for this oil bath.
  • a cooling line can also be provided, in particular encapsulated, in a wall of the bearing plate 14 and / or the cover 20
  • the pressure at the inlet 22 is usually essentially the same as at the outlet. During the pumping-out, however, the pressure at the inlet 22 drops to an end pressure which is essentially zero in terms of the resulting forces.
  • the pressure at the outlet 24 thus exerts a force on the rotors 28, 30 that is different than at the beginning of the pumping-out process.
  • a pretensioning device in particular a spring, can be provided, for example, which is provided in particular in the case of a floating bearing of the rotor and / or on the inlet side.
  • the preloading device can, for example, also absorb forces acting on the rotors by means of helically toothed gears and / or generally guarantee a design-appropriate preloading of the bearings regardless of the operating state with changing pressures or pressure conditions.
  • FIG. 5 an immersion cooler 34 is shown as it is arranged in the gear box 14 or in the cover 20 of the screw vacuum pump 10.
  • the immersion coolers 34 are designed identically, which leads to a low number of parts and low manufacturing costs.
  • the immersion cooler 34 has a cooling line 72 which runs through a heat sink 74.
  • the heat sink has a structure to increase the surface area of the heat sink in order to optimize the heat transfer.
  • the immersion cooler 34 also has a flange 76 with which the immersion cooler 34 is fastened.

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

Description

Die vorliegende Erfindung betrifft eine Schraubenvakuumpumpe mit einem Gehäuse, zwei in dem Gehäuse angeordneten und miteinander in Eingriff stehenden Schraubenrotoren, die zum Fördern eines Prozessgases in Zusammenwirkung mit dem Gehäuse wiederholt abgeschlossene Fördervolumina des Prozessgases bilden und in Richtung eines Auslasses fördern.The present invention relates to a screw vacuum pump with a housing, two screw rotors arranged in the housing and engaging with one another which, for conveying a process gas in cooperation with the housing, repeatedly form closed conveying volumes of the process gas and convey them in the direction of an outlet.

Die vakuumtechnische Leistung von Schraubenvakuumpumpen ist in hohem Maße abhängig von der Größe und Zahl von Spalten im pumpaktiven Bereich, insbesondere zwischen miteinander in Eingriff befindlichen Schraubenrotoren und zwischen einem jeweiligen Schraubenrotor und einer umschließenden Gehäusewand. Diese Spalte verändern sich im Betrieb bzw. im Vergleich zum Stillstand durch wärmeabhängige Formänderungen, insbesondere Ausdehnungen, der beteiligten Komponenten. Durch Kontrolle von Wärmeentwicklung und Begrenzung bzw. Verminderung von hohen Temperaturen in der Schraubenpumpe kann der Einfluss der Temperatur auf Spalte und damit auf die vakuumtechnische Leistung der Schraubenpumpe verbessert werden.The vacuum performance of screw vacuum pumps is to a large extent dependent on the size and number of gaps in the active pumping area, in particular between screw rotors that are in engagement and between a respective screw rotor and an enclosing housing wall. These gaps change during operation or in comparison to standstill due to heat-dependent changes in shape, in particular expansion, of the components involved. By controlling the generation of heat and limiting or reducing high temperatures in the screw pump, the influence of the temperature on gaps and thus on the vacuum performance of the screw pump can be improved.

Darüber hinaus entspricht Wärme auch, sofern sie nicht mancherorts erwünscht ist, grundsätzlich Verlusten, sodass eine Reduzierung von Wärmeproduktion die Effizienz der Schraubenvakuumpumpe verbessern kann. Es besteht ein enger Zusammenhang zwischen der Leistungsaufnahme der Pumpe und der resultierenden Wärme, wobei eine hohe Leistungsdichte eine effektive Wärmeabfuhr erforderlich macht.In addition, if it is not desired in some places, heat basically corresponds to losses, so that a reduction in heat production can improve the efficiency of the screw vacuum pump. There is a close relationship between the power consumption of the pump and the resulting heat, with a high power density making effective heat dissipation necessary.

Eine Schraubenvakuumpumpe nach dem Oberbegriff des Anspruchs 1 offenbaren die DE 197 45 615 A1 , die DE 197 45 616 A1 und die DE 101 56 179 A1 .A screw vacuum pump according to the preamble of claim 1 disclose DE 197 45 615 A1 , the DE 197 45 616 A1 and the DE 101 56 179 A1 .

Es ist eine Aufgabe der Erfindung, den Temperaturhaushalt einer Schraubenvakuumpumpe der eingangs genannten Art zu verbessern.It is an object of the invention to improve the temperature balance of a screw vacuum pump of the type mentioned at the beginning.

Diese Aufgabe wird durch die Merkmale des Anspruchs 1 gelöst.This object is achieved by the features of claim 1.

Offenbart wird außerdem eine Schraubenvakuumpumpe mit einem Gehäuse, zwei in dem Gehäuse angeordneten und miteinander in Eingriff stehenden Schraubenrotoren, die zum Fördern eines Prozessgases in Zusammenwirkung mit dem Gehäuse wiederholt abgeschlossene Fördervolumina des Prozessgases bilden und in Richtung eines Auslasses fördern, wobei die Schraubenvakuumpumpe zumindest eines der im Folgenden beschriebenen Merkmale aufweist.Also disclosed is a screw vacuum pump with a housing, two screw rotors arranged in the housing and engaging with one another, which repeatedly form closed delivery volumes of the process gas in cooperation with the housing for delivering a process gas and deliver in the direction of an outlet, the screw vacuum pump at least one of the features described below.

Es kann ein Motor vorgesehen sein, der als Direktantrieb für einen der Schraubenrotoren ausgebildet ist. Da der Motor als Direktantrieb ausgebildet ist, muss keine Kupplung zwischen dem Motor und dem betreffenden Schraubenrotor vorgesehen werden. Da eine Kupplung im Betrieb grundsätzlich Wärme erzeugt, wird somit eine Wärmequelle vollständig vermieden. Außerdem werden so die entsprechenden mechanischen Verluste in der Kupplung vermieden, wodurch die Energieeffizienz der Pumpe verbessert wird.A motor can be provided which is designed as a direct drive for one of the screw rotors. Since the motor is designed as a direct drive, there is no need to provide a coupling between the motor and the relevant screw rotor. Since a clutch generally generates heat during operation, a heat source is completely avoided. In addition, the corresponding mechanical losses in the coupling are avoided, which improves the energy efficiency of the pump.

Es kann eine aktive Flüssigkeitskühlung vorgesehen sein. Der Begriff "aktive Kühlung" bezieht sich auf eine fremdbetätigte Kühlung, also insbesondere eine Flüssigkeitskühlung mit einer Pumpe. Dabei kann z.B. eine separate Pumpe vorgesehen werden oder ein an einer Hausanschlussleitung ohnehin vorgesehener Wasserdruck ausgenutzt werden. Zum Beispiel kann die aktive Kühlung eine Wasserkühlung umfassen. Die aktive Kühlung sorgt für einen schnellen Wärmeabtransport und hilft so dabei, die Temperaturen in der Schraubenpumpe zu begrenzenActive liquid cooling can be provided. The term “active cooling” relates to externally operated cooling, that is to say in particular liquid cooling with a pump. For example, a separate pump can be provided or a water pressure that is already provided on a house connection can be used. For example, the active cooling can include water cooling. The active cooling ensures rapid heat dissipation and thus helps to limit the temperatures in the screw pump

Es kann die aktive Flüssigkeitskühlung sowohl für die Schraubenrotoren als auch für den Motor vorgesehen sein. Somit werden die Temperaturen sowohl im Bereich des Motors als auch im Bereich der Schraubenrotoren begrenzt, also an Orten in der Pumpe, an denen eine besonders hohe Wärmeentwicklung erwartet wird. Der Begriff "für" umfasst sowohl eine aktive Kühlung im Bereich des betreffenden Elements, also z.B. im Bereich der Schraubenrotoren bzw. des Motors, als auch eine Ausführung unmittelbar in dem betreffenden Element. So kann beispielsweise im Rahmen der Erfindung eine aktive Flüssigkeitskühlung in oder an dem Gehäuse für die Schraubenrotoren in einem, insbesondere axialen Bereich vorgesehen sein, in dem die Schraubenrotoren angeordnet sind. Grundsätzlich kann eine einzige aktive Flüssigkeitskühlung sowohl für den Motor als auch für die Schraubenrotoren vorgesehen sein oder es können auch mehrere aktive Flüssigkeitskühlungen vorgesehen sein.Active liquid cooling can be provided both for the screw rotors and for the motor. Thus, the temperatures are limited both in the area of the motor and in the area of the screw rotors, i.e. on Locations in the pump where particularly high levels of heat are expected. The term “for” encompasses both active cooling in the area of the element in question, that is to say, for example, in the area of the screw rotors or the motor, as well as an implementation directly in the element in question. For example, within the scope of the invention, active liquid cooling can be provided in or on the housing for the screw rotors in an area, in particular an axial area, in which the screw rotors are arranged. In principle, a single active liquid cooling system can be provided both for the motor and for the screw rotors, or several active liquid cooling systems can also be provided.

Insbesondere bildet der direkt angetriebene Schraubenrotor einen Läufer des Motors. Somit ist keine zusätzliche Lagerung für einen Schraubenrotor nötig, was mechanische Verluste und entsprechende Wärmeproduktion noch weiter verringert.In particular, the directly driven screw rotor forms a rotor of the motor. This means that no additional storage is required for a screw rotor, which further reduces mechanical losses and corresponding heat production.

Der Motor kann z.B. als Permanentmagnetsynchronmaschine, insbesondere mit innenliegenden Magneten bzw. als IPMSM, ausgebildet sein. So lässt sich die Effizienz weiter steigern, insbesondere da sich durch einen IPMSM ein besonders hoher Wirkungsgrad erreichen lässt.The motor can be designed, for example, as a permanent magnet synchronous machine, in particular with internal magnets or as an IPMSM. In this way, the efficiency can be increased further, especially since a particularly high degree of efficiency can be achieved with an IPMSM.

Gemäß einer Ausführungsform ist ein, insbesondere externer, Frequenzumrichter für den Motor vorgesehen. Insbesondere mangels beweglicher Teile trägt dieser ebenfalls zur Verringerung mechanischer Verluste bei. So muss z.B. kein Übersetzungsgetriebe zwischen dem Motor und dem betreffenden Schraubenrotor vorgesehen werden. Da ein Übersetzungsgetriebe im Betrieb grundsätzlich Wärme erzeugt, wird somit eine weitere Wärmequelle vollständig vermieden. Außerdem werden so die entsprechenden mechanischen Verluste in dem Übersetzungsgetriebe vermieden, wodurch die Energieeffizienz der Pumpe weiter verbessert wird. Abgesehen davon, dass kein Übersetzungsgetriebe zwischen dem Motor und dem entsprechenden Schraubenrotor notwendig ist, kann jedoch z.B. ein Synchronisierungsgetriebe zwischen den Schraubenrotoren vorgesehen sein.According to one embodiment, an, in particular external, frequency converter is provided for the motor. In particular, due to the lack of moving parts, this also helps to reduce mechanical losses. For example, no transmission gear has to be provided between the motor and the relevant screw rotor. Since a transmission gear always generates heat during operation, another heat source is completely avoided. In addition, the corresponding mechanical losses in the transmission gear are avoided, as a result of which the energy efficiency of the pump is further improved. Apart from the fact that there is no transmission gear between the motor and the corresponding screw rotor is necessary, however, a synchronization gear can be provided between the screw rotors, for example.

Bei einer weiteren Ausführungsform ist vorgesehen, dass die Schraubenrotoren jeweils zumindest zwei entlang der Schraubenachse benachbarte Abschnitte aufweisen, wobei die Schraubenrotoren jeweils in einem näher an einem Einlass gelegenen ersten Abschnitt eine zumindest im Wesentlichen konstante oder zunehmende Steigung und in einem zweiten Abschnitt eine niedrigere Steigung als im ersten Abschnitt aufweisen, und wobei in Bezug auf die Schraubenachse der erste Abschnitt länger ist als ein abgeschlossenes Fördervolumen im ersten Abschnitt, insbesondere länger als 360° bzw. eine Umdrehung des Schraubenprofils. Hierdurch wird eine Spaltlänge zwischen einem verdichtenden Bereich und einem Einlass der Pumpe vergrößert, wodurch die entsprechende Dichtwirkung verbessert wird. Die Pumpe kann somit effizienter ausgeführt werden. Außerdem lässt sich hierdurch eine notwendige Bearbeitungsgüte einer Abschlussfläche für die Schraubenrotoren im Einlassbereich verringern. Dies verringert die Herstellungskosten der Pumpe.In a further embodiment it is provided that the screw rotors each have at least two adjacent sections along the screw axis, the screw rotors each having an at least substantially constant or increasing gradient in a first section closer to an inlet and a lower gradient than in a second section in the first section, and wherein, with respect to the screw axis, the first section is longer than a closed delivery volume in the first section, in particular longer than 360 ° or one revolution of the screw profile. As a result, a gap length between a compressing area and an inlet of the pump is increased, as a result of which the corresponding sealing effect is improved. The pump can thus be made more efficient. In addition, a necessary processing quality of a closing surface for the screw rotors in the inlet area can be reduced as a result. This reduces the manufacturing cost of the pump.

Bei einer Weiterbildung ist im Bereich einer inneren Verdichtung der Pumpe ein Überdruckventil vorgesehen, welches mit einem Auslass der Pumpe verbunden ist oder einen Auslass bildet. Hierdurch kann der, insbesondere ohnehin nicht nützliche, Druck in diesem Bereich abgelassen werden, wenn er den am Auslass herrschenden Druck, also üblicherweise atmosphärischen Druck, übersteigt. Die innere Verdichtung wird somit auf atmosphärischen Druck begrenzt, was die für eine weitere Verdichtung nötige Antriebsleistung entbehrlich macht und entsprechend weitere Kompressionswärme vermeidet. Dies führt zu einer Verringerung der Temperatur.In a further development, a pressure relief valve is provided in the area of an internal compression of the pump, which is connected to an outlet of the pump or forms an outlet. As a result, the pressure in this area, which is in any case not useful, can be released if it exceeds the pressure prevailing at the outlet, that is to say usually atmospheric pressure. The internal compression is thus limited to atmospheric pressure, which makes the drive power necessary for further compression unnecessary and accordingly avoids further compression heat. This leads to a decrease in temperature.

Beispielsweise kann die Pumpe eine Steuereinrichtung aufweisen, die dazu ausgebildet und/oder eingerichtet ist, die Pumpe zumindest in einem Normalbetriebsmodus bei einer Rotordrehzahl von etwa 120 Hz oder weniger, insbesondere von etwa 120 Hz oder weniger und von etwa 80 Hz oder mehr, zu betreiben. Hierdurch werden eine entsprechend niedrige Leistungsaufnahme bzw. entsprechend niedrige mechanische Verluste erreicht. Dies gilt insbesondere im Bereich einer ausstoßenden Pumpstufe. Hier bzw. in einem Auslassbereich werden Rotor- und Gehäusetemperatur sowie Auslassgastemperatur niedrig gehalten.For example, the pump can have a control device which is designed and / or set up to operate the pump at least in a normal operating mode at a rotor speed of approximately 120 Hz or less, in particular of approximately 120 Hz or less and of approximately 80 Hz or more . This results in a correspondingly low power consumption or correspondingly low mechanical losses. This applies in particular in the area of an ejecting pump stage. Here or in an outlet area, the rotor and housing temperature as well as the outlet gas temperature are kept low.

Gemäß einer weiteren Ausführungsform ist die Steuereinrichtung dazu ausgebildet und/oder eingerichtet, die Pumpe zeitweise zumindest in einem Verstärkungsbetriebsmodus zu betreiben, bei dem die Rotordrehzahl höher ist als im Normalbetriebsmodus. Hierdurch kann die Leistung dann selektiv erhöht werden, wenn es nötig ist, während jedoch im Normalbetriebsmodus weiterhin die niedrige Leistungsaufnahme bzw. die niedrige Wärmeproduktion beibehalten werden. Es wird also eine insgesamt effiziente Pumpe zur Verfügung gestellt, die jedoch flexibel einsetzbar ist. Diese Ausführungsform ist beispielsweise besonders für Anwendung mit, insbesondere häufig, wiederholter Evakuierung vorteilhaft, da hier jeweils zum Beginn der Evakuierung bedarfsweise Leistung hinzugeschaltet werden kann, wobei die Leistungsaufnahme und Wärmeproduktion im Mittel relativ gering bleibt. Insbesondere kann es möglich sein, den flüssigkeitsgekühlten Motor kurzzeitig zu überlasten. So kann ein klein dimensionierter Motor zum Betrieb der Schraubenvakuumpumpe ausreichen.According to a further embodiment, the control device is designed and / or set up to operate the pump temporarily at least in a boost operating mode in which the rotor speed is higher than in the normal operating mode. As a result, the power can then be selectively increased if necessary, while, however, the low power consumption or the low heat production continues to be maintained in the normal operating mode. An overall efficient pump is thus made available, which can, however, be used flexibly. This embodiment is, for example, particularly advantageous for use with, in particular frequently, repeated evacuation, since here power can be switched on as required at the beginning of the evacuation, with the power consumption and heat production remaining relatively low on average. In particular, it may be possible to briefly overload the liquid-cooled motor. A small motor can be sufficient to operate the screw vacuum pump.

Eine Weiterbildung zeichnet sich dadurch aus, dass für zumindest einen der Schraubenrotoren eine berührungslose Dichtung, insbesondere ein Kolbenring, vorgesehen ist. Die Wärmeproduktion lässt sich hierdurch weiter reduzieren, insbesondere im Vergleich zu einer Pumpe mit Radialwellendichtringen.A further development is characterized in that a contactless seal, in particular a piston ring, is provided for at least one of the screw rotors. As a result, the heat production can be further reduced, especially in comparison to a pump with radial shaft sealing rings.

Es kann eine Schmiermittel-Abführeinrichtung, z.B. ein Deflektor, insbesondere benachbart zu einer Dichtung, vorgesehen sein. Diese kann eine Dichtung für einen Schraubenrotor unterstützen, indem ein insbesondere großer Teil des Schmiermittels, z.B. Öl, bereits gar nicht die Dichtung erreicht, sondern zuvor abgeführt wird. Dies kann insbesondere eine berührungslose Dichtung in ihrer Dichtwirkung verbessern.A lubricant discharge device, for example a deflector, particularly adjacent to a seal, may be provided. This can support a seal for a screw rotor in that a particularly large part of the lubricant, e.g. oil, does not even reach the seal, but is drained away beforehand. In particular, this can improve the sealing effect of a contactless seal.

Die Schraubenrotoren können zum Beispiel über ein Synchronisierungsgetriebe gekoppelt sein, wobei das Synchronisierungsgetriebe eine gerade Verzahnung aufweist. Dieses weist im Eingriff eine kleine Berührungsfläche, insbesondere im Vergleich zu einer Schrägverzahnung, auf. Entsprechend gering ist die Wärmeproduktion im Eingriffsbereich eines entsprechend ausgelegten Getriebes.The screw rotors can be coupled, for example, via a synchronization gear, the synchronization gear having straight teeth. When engaged, this has a small contact area, in particular in comparison to helical teeth. The heat production in the area of engagement of an appropriately designed gear is correspondingly low.

Wärmetechnisch vorteilhaft ist es außerdem, wenn wenig Schmiermittel, z.B. Öl, für das Synchronisierungsgetriebe eingesetzt wird, wobei natürlich ausreichend Schmiermittel vorhanden sein muss, um die Schmierung zu gewährleisten. Die geringe Schmiermittelmenge führt zu geringen mechanischen Verlusten im Schmiermittel selbst, wie z.B. durch Planschen von Öl.From a thermal point of view, it is also advantageous if little lubricant, e.g. oil, is used for the synchronization gear, although sufficient lubricant must of course be available to ensure lubrication. The small amount of lubricant leads to low mechanical losses in the lubricant itself, e.g. through splashing of oil.

Es kann außerdem vorgesehen sein, dass die Pumpe derart ausgebildet ist, dass zumindest eine Wärmequelle, wie z.B. eine innere Verdichtung, ein Motor oder ein Getriebe, in der Nähe zumindest einer Wärmesenke, wie z.B. einer Flüssigkeitskühlung, angeordnet ist. Hierdurch wird eine besonders effektive Wärmeabfuhr gewährleistet.It can also be provided that the pump is designed in such a way that at least one heat source, such as, for example, an internal compression, a motor or a gearbox, is arranged in the vicinity of at least one heat sink, such as, for example, a liquid cooling system. This ensures particularly effective heat dissipation.

Erfindungsgemäß ist die Pumpe derart ausgebildet, dass zwischen zumindest einer Wärmequelle und zumindest einem wärmeempfindlichen Bereich, z.B. einem wärmeempfindlichen Bauteil und/oder einem ölgeschmierten Bereich, eine Abschirmung angeordnet ist.According to the invention, the pump is designed in such a way that a shield is arranged between at least one heat source and at least one heat-sensitive area, for example a heat-sensitive component and / or an oil-lubricated area.

Die Abschirmung ist durch eine Taillierung des Gehäuses gebildet. Die Taillierung begrenzt einen möglichen Wärmestrom und sorgt so für eine wirksame Isolation. Gleichzeitig lässt sich eine Taillierung einfach herstellen und es sind insbesondere keine zusätzlichen Isolierungen notwendig.The shield is formed by a waist of the housing. The waist limits a possible heat flow and thus ensures effective insulation. At the same time, a waist can be easily produced and, in particular, no additional insulation is necessary.

Insbesondere im Bereich einer Taillierung ist es vorteilhaft, eine aktive Kühlung vorzusehen. So lässt sich ein Wärmestau in diesem Bereich effektiv abführen. Die Taillierung wirkt dabei gewissermaßen wie eine Wärmesammelstelle für die aktive Kühlung, sodass die Wärme im Wesentlichen nicht oder kaum die Taillierung passiert, jedoch zu einem großen Teil der aktiven Kühlung zugeführt wird.In particular in the area of a waist it is advantageous to provide active cooling. This way, heat build-up in this area can be effectively dissipated. The waist acts to a certain extent as a heat collection point for the active cooling, so that the heat essentially does not or hardly passes through the waist, but is largely supplied to the active cooling.

Die Abschirmung kann insbesondere zwischen einem Auslass und einem Lagerabschnitt für die Schraubenrotoren vorgesehen sein. So kann insbesondere ein im Lagerabschnitt vorgesehenes Schmiermittel vor hohem Wärmeeintrag vom Auslassbereich geschützt werden, da Schmiermittel häufig temperaturempfindlich sind bzw. für höhere Temperaturen teurer in der Anschaffung sind.The shield can in particular be provided between an outlet and a bearing section for the screw rotors. In particular, a lubricant provided in the bearing section can be protected from high heat input from the outlet area, since lubricants are often temperature-sensitive or are more expensive to purchase for higher temperatures.

Die Abschirmung kann auch als Isolation, beispielsweise als eine Isolationsschicht, insbesondere mit einem schlecht wärmeleitenden Material, beispielsweise einem geschäumten Material oder einem Gas, wie z.B. Luft, ausgebildet sein. Beispielsweise kann ein Lagerabschnitt, insbesondere ein Lagerschild, als Sandwich-Bauteil, insbesondere mit einer Isolationsschicht, ausgebildet sein. Hierdurch kann der Wärmeübergang von einem pumpaktiven Bereich zum Lagerbereich weiter verringert werden.The shield can also be designed as insulation, for example as an insulation layer, in particular with a poorly thermally conductive material, for example a foamed material or a gas such as air. For example, a bearing section, in particular a bearing plate, can be designed as a sandwich component, in particular with an insulation layer. As a result, the heat transfer from an active pumping area to the storage area can be further reduced.

Bei einer weiteren Ausführungsform ist die Flüssigkeitskühlung derart ausgebildet, dass sie im Bereich einer Wärmequelle eine turbulente Strömung ausbildet. Hierdurch wird in diesem Bereich eine besonders guter Wärmeübergang gewährleistet. Grundsätzlich kann es von Vorteil sein, ein geringes Volumen, also insbesondere einen kleinen Leitungsquerschnitt und/oder eine geringe Gesamtflüssigkeitsmenge, für einen Kühlkreis und/oder eine hohe Strömungsgeschwindigkeit des Kühlfluids vorzusehen. Dies erlaubt einen besonders guten Wärmeübergang, insbesondere durch Ausbildung turbulenter Strömungsverhältnisse. Turbulenzen lassen sich beispielsweise auch durch lokale Verengungen einer Kühlleitung bzw. durch abrupte Änderungen ihrer Innenflächen erzeugen.In a further embodiment, the liquid cooling is designed in such a way that it forms a turbulent flow in the area of a heat source. This ensures particularly good heat transfer in this area. In principle, it can be advantageous to have a small volume, that is to say in particular Provide a small line cross-section and / or a small total amount of liquid for a cooling circuit and / or a high flow rate of the cooling fluid. This allows particularly good heat transfer, in particular due to the formation of turbulent flow conditions. Turbulence can also be generated, for example, by local narrowing of a cooling line or by abrupt changes in its inner surfaces.

Generell kann vorgesehen sein, eine effiziente Kühlung, insbesondere durch eine schnelle lokale Wärmeabfuhr, insbesondere direkt oder möglichst nah an einer Wärmequelle zu gewährleisten. Hierfür können beispielsweise Kühlleitungen der aktiven Kühlung Aluminium oder einen anderen Werkstoff hoher Wärmeleitfähigkeit umfassen, in einem Aluminiumgusskörper ausgebildet sein und/oder als, insbesondere in Gehäusenuten, eingepresste Kühlleitungen ausgebildet sein. Kühlleitungen sind insbesondere nah an einer Wärmequelle angeordnet und/oder folgen ihrer Kontur in möglichst geringem Abstand. Generell können Kühlkreise auch zur Kühlung verschiedener Wärmequellen aufgeteilt werden und/oder geeignet verschaltet werden. Dabei kann beispielsweise ein Abschnitt des Kühlkreises komplett für einen besonders warmen oder wärmeempflindlichen Bereich, insbesondere ein besonders warmes oder wärmeempfindliches Bauteil, vorgesehen sein, während beispielsweise andere Abschnitte des Kühlkreises für andere Bereich bzw. Bauteile, die weniger empfindlich sind oder weniger Wärme produzieren, in Reihe geschaltet werden können.In general, provision can be made to ensure efficient cooling, in particular by means of rapid local heat dissipation, in particular directly or as close as possible to a heat source. For this purpose, for example, cooling lines for active cooling can comprise aluminum or another material of high thermal conductivity, can be formed in a cast aluminum body and / or can be formed as cooling lines, in particular, pressed into housing grooves. Cooling lines are arranged in particular close to a heat source and / or follow their contour at the smallest possible distance. In general, cooling circuits can also be divided up and / or suitably connected to cool different heat sources. For example, a section of the cooling circuit can be provided completely for a particularly warm or heat-sensitive area, in particular a particularly warm or heat-sensitive component, while, for example, other sections of the cooling circuit for other areas or components that are less sensitive or produce less heat, in Can be connected in series.

Zur Verbesserung der Kühlleistung ist es außerdem vorteilhaft, Wärmequellen in der Pumpe gruppiert, benachbart und/oder in der Nähe voneinander anzuordnen. Hierdurch kann bereits eine lokale Kühlung ausreichen, um mehrere Wärmequellen gemeinsam zu kühlen. Konzentriert erzeugte Wärme lässt sich besonders gut abführen.In order to improve the cooling performance, it is also advantageous to arrange heat sources in the pump in a group, adjacent and / or close to one another. As a result, local cooling can be sufficient to cool several heat sources together. Heat generated in a concentrated manner can be dissipated particularly well.

Insbesondere kann es vorteilhaft sein, unvermeidbare Wärmequellen in der Nähe des Auslasses anzuordnen. Der Auslass stellt dabei insbesondere selbst eine Wärmequelle dar. Die Wärme ist hier lokal besonders effektiv abführbar.In particular, it can be advantageous to arrange unavoidable heat sources in the vicinity of the outlet. The outlet in particular represents a heat source itself. The heat can be dissipated particularly effectively locally here.

Es kann z.B. ein Tauchkühler vorgesehen sein, der insbesondere Aluminium umfasst. Der Tauchkühler kann beispielsweise in einem Bad eines Schmiermittels der Vakuumpumpe, insbesondere eines Sychnronisierungsgetriebes, insbesondere einem Ölbad, angeordnet sein. Hierdurch lässt sich die Temperatur eines empfindlichen Schmiermittels besonders gut kontrollieren bzw. kann in diesem temperaturempfindlichen Bereich für eine lokale Kühlung gesorgt werden, während andere Bereiche gegebenenfalls weniger stark gekühlt werden müssen.For example, an immersion cooler can be provided, which in particular comprises aluminum. The immersion cooler can be arranged, for example, in a bath of a lubricant of the vacuum pump, in particular a synchronization gear, in particular an oil bath. In this way, the temperature of a sensitive lubricant can be controlled particularly well or local cooling can be provided in this temperature-sensitive area, while other areas may have to be cooled less strongly.

Die Schraubenrotoren der Schraubenvakuumpumpe können insbesondere durch ein Zykloidenprofil gebildet sein bzw. ein solches aufweisen und/oder zweigängig ausgebildet sein. Eine Schraubensteigung der Schraubenrotoren kann beispielsweise abschnittsweise konstant ausgebildet sein, d.h. die Steigung verändert sich entlang einer Schraubenachse lediglich in Übergangsbereichen zwischen den Abschnitten, wobei ein Übergangsbereich insbesondere kleiner als ein Abschnitt ist, insbesondere alle Übergangsbereiche kleiner als alle Abschnitte sind.The screw rotors of the screw vacuum pump can in particular be formed by a cycloid profile or have such a profile and / or be designed with two threads. A screw pitch of the screw rotors can, for example, be constant in sections, i.e. the pitch changes along a screw axis only in transition areas between the sections, with one transition area being in particular smaller than one section, in particular all transition areas being smaller than all sections.

Ein Auslass der Pumpe kann zum Beispiel nach unten hin ausgerichtet sein. Ein Einlass der Pumpe kann zum Beispiel nach oben hin ausgerichtet sein.For example, an outlet of the pump can be directed downwards. For example, an inlet of the pump can be directed upwards.

Die Schraubenvakuumpumpe kann beispielsweise eine innere Verdichtung mit einem Verdichtungsverhältnis kleiner als 5 zu 1, inbesondere kleiner als 4 zu 1, insbesondere kleiner als 3,5 zu 1, und/oder größer als 2 zu 1, insbesondere größer als 3 zu 1, aufweisen. Ein jeweiliges Schraubenprofil kann z.B. mehr als 7, insbesondere mehr als 10, insbesondere mehr als 12, insbesondere 13 abgeschlossene Fördervolumina gleichzeitig bilden bzw fördern. Ein jeweiliger Schraubenrotor kann insbesondere ein Verhältnis der Länge seines Schraubenprofils zu dessen Durchmesser von wenigstens 2,0, insbesondere wenigstens 2,5, insbesondere wenigstens 3,0 und/oder höchstens 5,0, insbesondere höchstens 4,0, aufweisen.The screw vacuum pump can, for example, have an internal compression with a compression ratio of less than 5 to 1, in particular less than 4 to 1, in particular less than 3.5 to 1, and / or greater than 2 to 1, in particular greater than 3 to 1. A respective screw profile can, for example, simultaneously form or convey more than 7, in particular more than 10, in particular more than 12, in particular 13 closed conveying volumes. A respective screw rotor can in particular have a ratio of the length of its screw profile to its Have a diameter of at least 2.0, in particular at least 2.5, in particular at least 3.0 and / or at most 5.0, in particular at most 4.0.

Bei einem beispielhaften Verfahren zum Betrieb eines Vakuumsystems mit einer Schraubenvakuumpumpe, insbesondere gemäß einer hierin beschriebenen Art, wird eine Vakuumkammer, insbesondere häufig, insbesondere mehrmals am Tag, insbesondere mehrmals in der Stunde, wiederholt evakuiert, wobei insbesondere eine der Schraubenpumpe vorgeschaltete Wälzkolbenpumpe vorgesehen ist, wobei insbesondere die Wälzkolbenpumpe ein Saugvermögen aufweist, welches höchstens dreimal, insbesondere höchstens oder etwa doppelt, so groß ist wie ein Saugvermögen der Schraubenvakuumpumpe.In an exemplary method for operating a vacuum system with a screw vacuum pump, in particular according to a type described herein, a vacuum chamber is evacuated repeatedly, in particular frequently, in particular several times a day, in particular several times an hour, in particular a Roots pump connected upstream of the screw pump is provided, wherein in particular the Roots pump has a pumping speed which is at most three times, in particular at most or approximately twice, as great as a pumping speed of the screw vacuum pump.

Da bei wiederholten Evakuierungen, die auch als Load-Lock-Anwendungen bezeichnet werden, häufig bzw. insgesamt relativ lange bei hohen Drücken nahe Atmosphäre gearbeitet wird, führt das genannte vorteilhafte Saugvermögensverhältnis und/oder ein geringes Verdichtungsverhältnis dazu, dass nur eine geringe Verdichtungsleistung aufgebracht werden muss und nur eine geringe Verdichtungswärme entsteht, die hierdurch leicht abzuführen ist. Somit wird ein besonders effizienter Betrieb des Vakuumsystems ermöglicht.Since repeated evacuations, which are also referred to as load-lock applications, work frequently or for a relatively long time at high pressures close to the atmosphere, the aforementioned advantageous pumping speed ratio and / or a low compression ratio means that only a low compression output is applied must and only a small amount of compression heat is generated, which is easy to dissipate. This enables particularly efficient operation of the vacuum system.

Bei einem weiteren beispielhaften Verfahren zum Betrieb eines Vakuumsystems mit einer Schraubenvakuumpumpe, insbesondere gemäß einer hierin beschriebenen Art, wird eine Vakuumkammer bei einem Enddruck im Wesentlichen dauerhaft betrieben, wobei insbesondere eine der Schraubenpumpe vorgeschaltete Wälzkolbenpumpe vorgesehen ist, wobei insbesondere die Wälzkolbenpumpe ein Saugvermögen aufweist, welches wenigstens fünfmal, insbesondere wenigstens siebenmal, so groß ist wie ein Saugvermögen der Schraubenvakuumpumpe.In a further exemplary method for operating a vacuum system with a screw vacuum pump, in particular according to a type described herein, a vacuum chamber is operated essentially permanently at a final pressure, in particular a Roots pump connected upstream of the screw pump being provided, the Roots pump in particular having a pumping speed which is at least five times, in particular at least seven times, as great as a pumping speed of the screw vacuum pump.

Bei vornehmlichem Betrieb im Enddruck führt das genannte vorteilhafte Saugvermögensverhältnis und/oder ein hohes Verdichtungsverhältnis nicht zu den oben geschilderten Nachteilen. Vielmehr lässt sich hierdurch eine klein dimensionierte Schraubenvakuumpumpe einsetzen, was kostentechnisch vorteilhaft ist.In the case of primarily operation at final pressure, the aforementioned advantageous pumping speed ratio and / or a high compression ratio do not lead to the above disadvantages described. Rather, a small-dimensioned screw vacuum pump can be used as a result, which is advantageous in terms of costs.

Falls sowohl eine wiederholte Evakuierung als auch ein relativ langer Betrieb im Enddruck notwendig sind oder ermöglich werden sollen, kann es vorteilhaft sein, das Saugvermögensverhältnis und/oder das Verdichtungsverhältnis so auszulegen, dass ein geeigneter Kompromiss erzielt wird.If both repeated evacuation and relatively long operation at the final pressure are necessary or should be made possible, it can be advantageous to design the pumping speed ratio and / or the compression ratio so that a suitable compromise is achieved.

Die hierin beschriebenen Pumpen, Pumpsysteme und Verfahren lassen sich im Sinne aller hierin beschriebenen Merkmale bzw. Maßnahmen für Pumpen, Pumpsysteme und Verfahren weiterbilden.The pumps, pump systems and methods described herein can be developed further in the sense of all the features or measures described herein for pumps, pump systems and methods.

Die Erfindung wird nachfolgend lediglich beispielhaft anhand der schematischen Zeichnung erläutert.

Fig. 1
zeigt eine Schraubenvakuumpumpe in perspektivischer Ansicht.
Fig. 2
zeigt die Schraubenvakuumpumpe der Fig. 1 in einer Draufsicht.
Fig. 3
zeigt die Schraubenvakuumpumpe der Fig. 1 und 2 in einer Seitenansicht.
Fig. 4
zeigt eine Schnittansicht der Schraubenvakuumpumpe entlang einer in Fig. 3 angedeuteten Schnittebene A-A.
Fig. 5
zeigt einen Tauchkühler der Schraubenvakuumpumpe der Fig. 1 bis 4.
The invention is explained below by way of example only with reference to the schematic drawing.
Fig. 1
shows a screw vacuum pump in a perspective view.
Fig. 2
shows the screw vacuum pump of the Fig. 1 in a top view.
Fig. 3
shows the screw vacuum pump of the Fig. 1 and 2 in a side view.
Fig. 4
FIG. 13 shows a sectional view of the screw vacuum pump along a line in FIG Fig. 3 indicated section plane AA.
Fig. 5
shows an immersion cooler of the screw vacuum pump of Figs. 1 to 4 .

In den Fig. 1 bis 3 ist eine Schraubenvakuumpumpe 10 gezeigt, die einen Motor 12, einen Getriebekasten 14, ein Gehäuse 16, einen Lagerschild 18 sowie einen Deckel 20 aufweist. Die Schraubenvakuumpumpe 10 fördert ein Prozessgas von einem Einlass 22 zu einem nach unten gerichteten, in Fig. 3 sichtbaren Auslass 24.In the Figs. 1 to 3 a screw vacuum pump 10 is shown, which has a motor 12, a gear box 14, a housing 16, a bearing plate 18 and a cover 20. The screw vacuum pump 10 conveys a process gas from an inlet 22 to a downwardly directed, in Fig. 3 visible outlet 24.

Für den Motor 12 ist eine aktive Flüssigkeitskühlung vorgesehen, die aus einem Gehäuse des Motors 12 austritt. Für im Inneren des Gehäuses 16 angeordnete und in Fig. 4 sichtbare Schraubenrotoren 28 und 30 ist ebenfalls eine aktive Flüssigkeitskühlung vorgesehen, die zwei Kühlleitungen aufweist, welche in Fig. 1 nicht dargestellt sind, deren Verlauf aber durch entsprechende Nuten 32 des Gehäuses 16 angedeutet ist, in die die Kühlleitungen eingepresst werden. Des Weiteren sind aktive Flüssigkeitskühlungen im Getriebekasten 14 und im Deckel 20 vorgesehen und hier jeweils als Tauchkühler 34 ausgebildet, die unten anhand von Fig. 5 näher erläutert werden.Active liquid cooling, which emerges from a housing of the motor 12, is provided for the motor 12. For arranged inside the housing 16 and in Fig. 4 Visible screw rotors 28 and 30, active liquid cooling is also provided, which has two cooling lines which are shown in FIG Fig. 1 are not shown, but their course is indicated by corresponding grooves 32 of the housing 16 into which the cooling lines are pressed. Furthermore, active liquid cooling systems are provided in the gear box 14 and in the cover 20 and are each designed here as an immersion cooler 34, which are shown below with reference to FIG Fig. 5 are explained in more detail.

Wie es in den Fig. 1 bis 4 ersichtlich ist, weist das Gehäuse 16 der Schraubenvakuumpumpe 10 eine Taillierung 36 auf. Die Taillierung 36 ist im Bereich des Auslasses 24 angeordnet.Like it in the Figs. 1 to 4 As can be seen, the housing 16 of the screw vacuum pump 10 has a waist 36. The waist 36 is arranged in the area of the outlet 24.

In Fig. 4 ist die Schraubenvakuumpumpe 10 in einer Schnittansicht gezeigt, deren Schnittebene der Linie A-A in Fig. 3 entspricht. Es sind zwei Schraubenrotoren 28 und 30 sichtbar, die jeweils zweigängige, ineinandergreifende Schraubenprofile 38 und 40 aufweisen, die mit Hilfe eines Zykloidenprofil generiert sind und eine zylindrische Hüllkontur sowie eine zylindrische Grundform des Schraubengrundes aufweisen. Die Schraubenprofile 38 und 40 bilden in Zusammenwirkung mit dem Gehäuse 16 einen pumpaktiven Bereich der Schraubenvakuumpumpe 10 und fördern wiederholt abgeschlossene Fördervolumina des Prozessgases vom Einlass 22 zum Auslass 24, in Fig. 4 also von links nach rechts.In Fig. 4 the screw vacuum pump 10 is shown in a sectional view, the sectional plane of the line AA in FIG Fig. 3 corresponds to. Two screw rotors 28 and 30 are visible, each having two-thread, interlocking screw profiles 38 and 40, which are generated with the aid of a cycloid profile and have a cylindrical envelope contour and a cylindrical basic shape of the screw base. The screw profiles 38 and 40, in cooperation with the housing 16, form an active pumping area of the screw vacuum pump 10 and repeatedly convey closed volumes of the process gas from the inlet 22 to the outlet 24, in Fig. 4 so from left to right.

Die Pumpleistung der Schraubenvakuumpumpe 10 hängt von Größe und Gestalt verschiedener Spalte im pumpaktiven Bereich ab, die aufgrund der Relativbewegung von Rotoren 28, 30 und Gehäuse 16 zwar unvermeidbar sind, jedoch zwecks guter Pumpleistung klein und möglichst konstant zu halten sind. Temperaturänderungen in den beteiligten Bauteilen führen zu deren Formänderung. Die hierin beschriebenen Maßnahmen zur Vermeidung, Abführung und im Allgemeinen Beherrschung von Wärme in der Pumpe 10 bewirken somit eine möglichst geringe Formänderung und in der Folge möglichst beherrschbare Spalte. Die Spalte können also präziser ausgelegt werden, was die Pumpleistung bzw. ihre Effizienz verbessert.The pumping power of the screw vacuum pump 10 depends on the size and shape of various gaps in the active pumping area, which are unavoidable due to the relative movement of rotors 28, 30 and housing 16, but must be kept small and as constant as possible for the purpose of good pumping power. Changes in temperature in the components involved lead to their shape change. The measures described herein for avoiding, dissipating and generally controlling heat in the pump 10 thus result in the smallest possible change in shape and consequently the most manageable gaps possible. The gaps can therefore be designed more precisely, which improves the pump performance and its efficiency.

Der Schraubenrotor 28 wird direkt, also ohne zwischengeschaltete Kupplung, von dem Motor 12 angetrieben. Der Schraubenrotor 30 wird dagegen über ein Synchronisierungsgetriebe 42 mit Zahnrädern 43 in einem definierten Winkelverhältnis zum Schraubenrotor 28 angetrieben.The screw rotor 28 is driven directly by the motor 12, that is to say without an interposed coupling. The screw rotor 30, on the other hand, is driven via a synchronization gear 42 with gears 43 in a defined angular relationship to the screw rotor 28.

Der Motor 12 umfasst ein Gehäuse 44, welches zum Beispiel aus Aluminium hergestellt ist und in welchem Kühlleitungen 26 für die aktive Flüssigkeitskühlung ausgebildet sind. Der Motor 12 umfasst außerdem einen gewickelten Stator 46, der zusammen mit einem auf einem Wellenende des Schraubenrotors 28 angebrachten Magnetträger 48 einen elektrischen Motor und einen Direktantrieb für den Schraubenrotor 28 bildet. Der Schraubenrotor 28 bildet einen Läufer des Motors 12. Der Magnetträger 48 umfasst eine Mehrzahl an Permanentmagneten. Der Motor 12 bildet also eine Permanentmagnetsynchronmaschine mit innenliegenden Magneten, welche auch als IPMSM bezeichnet wird.The motor 12 comprises a housing 44, which is made, for example, of aluminum and in which cooling lines 26 are formed for active liquid cooling. The motor 12 also comprises a wound stator 46 which, together with a magnet carrier 48 attached to a shaft end of the screw rotor 28, forms an electric motor and a direct drive for the screw rotor 28. The screw rotor 28 forms a rotor of the motor 12. The magnet carrier 48 comprises a plurality of permanent magnets. The motor 12 thus forms a permanent magnet synchronous machine with internal magnets, which is also referred to as IPMSM.

Der Stator 46 ist in einem Vergusskörper 50 angeordnet, welcher nicht näher dargestellte elektrische Leiter beim Stator 46 isoliert und diese isoliert zu einer Platine 52 führt. Der Vergusskörper 50 bildet hier in Verbindung mit der Platine 52 einen vakuumdichten Anschluss des Motors 12 an eine in einem Bereich atmosphärischen Drucks vorgesehene Steuerungselektronik. Es kann z.B. ein externer Frequenzumrichter für den Motor 12 vorgesehen sein. Alternativ oder zusätzlich kann auf der Platine 52 zumindest ein Teil einer Steuerungselektronik für den Motor 12 vorgesehen sein.The stator 46 is arranged in a potting body 50, which insulates electrical conductors (not shown in greater detail) at the stator 46 and leads them to a circuit board 52 in an insulated manner. The potting body 50 forms here, in conjunction with the circuit board 52, a vacuum-tight connection of the motor 12 to a connection which is atmospheric in an area Control electronics provided for pressure. For example, an external frequency converter can be provided for the motor 12. As an alternative or in addition, at least part of an electronic control system for the motor 12 can be provided on the circuit board 52.

In dem Getriebekasten 14 ist das Synchronisierungsgetriebe 42 angeordnet. Im Getriebekasten 14 ist außerdem Öl als Schmiermittel vorgesehen, welches durch Spritzscheiben 54 über das Synchronisierungsgetriebe 42 und benachbarte Lager 56 verteilt wird.The synchronization gear 42 is arranged in the gear box 14. In the gear box 14, oil is also provided as a lubricant, which is distributed by splash disks 54 via the synchronization gear 42 and adjacent bearings 56.

Die Tailllierung 36 bildet eine Abschirmung bzw. eine Wärmebarriere, und zwar insbesondere für Wärme, die im Bereich der Schraubenrotoren 28, 30 während des Pumpbetriebs produziert wird. Dadurch, dass ein geringer Materialquerschnitt verbleibt, und dadurch, dass durch die Formänderung ein Wärmepfad verlängert ist, wird die Wärme vom Schraubenrotor, die sich ansonsten im Gehäuse 16 ausbreitet, daran gehindert, in jenseitige Bereiche zu gelangen. So werden insbesondere das Öl im Getriebekasten 14 und die Lager 56 vor zu hohen Temperaturen geschützt. Der im Getriebekasten 14 angeordnete Tauchkühler 34 trägt ebenfalls zur Temperaturreduzierung bei. Dieser ist in einem nicht dargestellten Ölbad des Getriebekastens 14 angeordnet und kühlt somit das Öl direkt.The waist 36 forms a shield or a thermal barrier, in particular for heat that is produced in the area of the screw rotors 28, 30 during the pumping operation. Because a small material cross-section remains, and because a heat path is lengthened as a result of the change in shape, the heat from the screw rotor, which otherwise spreads in the housing 16, is prevented from reaching the areas on the other side. In particular, the oil in the gear box 14 and the bearings 56 are protected from excessively high temperatures. The immersion cooler 34 arranged in the gear box 14 also contributes to the temperature reduction. This is arranged in an oil bath, not shown, of the gear box 14 and thus cools the oil directly.

Für einen jeweiligen Schraubenrotor 28 bzw. 30 ist benachbart zu den Lagern 56, die hier eine Festlagerung bilden, eine als Deflektor 58 ausgebildete Schmiermittel-Abführeinrichtung vorgesehen. Ein jeweiliger Deflektor 58 bildet eine Barriere für das Öl im Getriebekasten, damit es nicht in einen pumpaktiven Bereich oder einen Vakuumbereich, hier insbesondere einen Auslassbereich, gelangt. Der Deflektor 58 umfasst eine nicht näher veranschaulichte Abschleuderkante für das Öl. Gegenüber der Abschleuderkante ist im Gehäuse 16 eine Ablaufnut ausgebildet, die abgeschleudertes Öl aufnimmt und dieses zurück in den Getriebekasten 14 bzw. in ein dortiges Ölbad leitet. Das Öl, welches durch die Spritzscheiben 54 auf Getriebe 42 und Lager 56 gefördert bzw. verteilt wird, wird somit durch die Deflektoren 58 wieder von den Rotoren 28 bzw. 30 abgeführt.For a respective screw rotor 28 or 30, a lubricant discharge device designed as a deflector 58 is provided adjacent to the bearings 56, which here form a fixed bearing. A respective deflector 58 forms a barrier for the oil in the gear box so that it does not get into a pump-active area or a vacuum area, here in particular an outlet area. The deflector 58 comprises a throw-off edge, not shown in detail, for the oil. Opposite the throwing-off edge, a drainage groove is formed in the housing 16, which takes up thrown-off oil and returns it in the gear box 14 or in an oil bath there. The oil, which is conveyed or distributed by the splash disks 54 to the gears 42 and bearings 56, is thus carried away again from the rotors 28 and 30 by the deflectors 58.

Als dynamische Fluiddichtung sind Kolbenringe auf einem Kolbenringträger 60 vorgesehen. Diese bilden eine berührungslose Dichtung und vermeiden somit Reibungswärme. Die Deflektoren 58 führen möglichst viel Öl zum Getriebekasten 14 zurück, sodass bereits möglichst wenig Öl an den Kolbenringen ansteht. So wird eine insgesamt zuverlässige Dichtwirkung bei besonders geringer Wärmeproduktion erreicht.Piston rings are provided on a piston ring carrier 60 as a dynamic fluid seal. These form a contactless seal and thus avoid frictional heat. The deflectors 58 return as much oil as possible to the gear box 14 so that as little oil as possible is already present on the piston rings. In this way, an overall reliable sealing effect is achieved with particularly low heat production.

Die Schraubenrotoren 28 und 30 weisen in ihrem jeweiligen Schraubenprofil 38 bzw. 40 drei Abschnitte unterschiedlicher Steigung auf. Ein in Pumprichtung erster Abschnitt 62, in Fig. 4 links, bildet einen Ansaugabschnitt und weist eine konstante und die größte Steigung unter den drei Abschnitten auf. Der erste Abschnitt 62 ist in Bezug auf eine Schraubenachse 63, die entlang eines jeweiligen Rotors 28 bzw. 30 verläuft, länger als ein abschlossenes Fördervolumen im ersten Abschnitt. Ein zweiter Abschnitt 64 weist mehrere Unterabschnitte, die nicht näher referenziert sind, mit verschiedenen aber jeweils konstanten Steigungen im Schraubenprofil 38 bzw. 40 auf, wobei die Steigungen niedriger sind, als im ersten Abschnitt. Der zweite Abschnitt 64 bildet hier den längsten Abschnitt. Ein dritter Abschnitt 66 mit noch niedrigerer Steigung bildet einen Ausstoßabschnitt. Im dritten Abschnitt liegt wiederum eine konstante Steigung vor. Durch die entlang der Pumprichtung verminderte Steigung wird eine innere Verdichtung bewirkt, die das Prozessgas schon vor dem Ausstoßen verdichtet.The screw rotors 28 and 30 have three sections of different pitch in their respective screw profile 38 and 40, respectively. A first section 62 in the pumping direction in Fig. 4 left, forms a suction section and has a constant and the greatest slope among the three sections. The first section 62 is longer in relation to a screw axis 63, which runs along a respective rotor 28 or 30, than a closed delivery volume in the first section. A second section 64 has a plurality of subsections, which are not referenced in any more detail, with different but constant slopes in the screw profile 38 or 40, the slopes being lower than in the first section. The second section 64 here forms the longest section. A third section 66 with an even lower slope forms an ejection section. In the third section there is again a constant slope. The reduced slope along the pumping direction brings about an internal compression that compresses the process gas even before it is ejected.

Die Rotoren 28, 30 bzw. die Schraubenprofile 38, 40 lassen sich durch das Vorsehen der konstanten Abschnitte besonders einfach auslegen und fertigen. Wie es anhand von Fig. 4 ersichtlich ist, führt ein verlängerter erster Abschnitt 62 zu entsprechend verlängerten Spalten zwischen den Schraubenprofilen 28, 30 und dem Gehäuse 16, sodass der Weg bzw. die Spalte von der inneren Verdichtung am Übergang der Abschnitte 62 und 64 hin zu einem Schöpfraum oder Ansaugbereich 67 länger ist. Entsprechend erhöht ist also die Dichtwirkung der Spalte, was insbesondere bei hohen Differenzdrücken zu einer verbesserten Abdichtung der inneren Verdichtung gegenüber dem Ansaugbereich 67 führt.The rotors 28, 30 or the screw profiles 38, 40 can be designed and manufactured particularly easily by providing the constant sections. How it is based on Fig. 4 As can be seen, an elongated first section 62 leads to correspondingly elongated gaps between the screw profiles 28, 30 and the Housing 16, so that the path or the gap from the inner compression at the transition of the sections 62 and 64 to a suction chamber or suction area 67 is longer. The sealing effect of the gaps is correspondingly increased, which leads to an improved sealing of the inner compression with respect to the suction area 67, particularly at high differential pressures.

Die Schraubenvakuumpumpe 10 weist also eine innere Verdichtung auf. Die Schraubenrotoren 28, 30 der Pumpe 10 schließen in Zusammenwirkung mit dem Gehäuse 16 wiederholt abgeschlossene Fördervolumina ein. Deren Größe ist an einem einlassseitigen Ende bzw. im Abschnitt 62 größer als an einem auslassseitigen Ende bzw. im Abschnitt 62. Die Größe eines Fördervolumens wird durch einen Querschnitt eines Schraubenprofils 38, 40 und dessen Steigung bestimmt.The screw vacuum pump 10 thus has an internal compression. The screw rotors 28, 30 of the pump 10, in cooperation with the housing 16, repeatedly enclose closed delivery volumes. Their size is larger at an inlet-side end or in section 62 than at an outlet-side end or in section 62. The size of a delivery volume is determined by a cross section of a screw profile 38, 40 and its pitch.

Die Größe eines Fördervolumens auf der Einlassseite bzw. im Abschnitt 62 bestimmt ein theoretisches Saugvermögen der Schraubenpumpe 10. Die Steigung des Schraubenprofils 38, 40 ist einlassseitig über Abschnitt 62 konstant, damit das Fördervolumen erst nach Abschluss durch die innere Verdichtung komprimiert wird. Schließt ein jeweiliger Rotor 28, 30 ein jeweiliges Fördervolumen zu früh oder zu spät bzw. beginnt die innere Verdichtung zu früh, sinkt das theoretische Saugvermögen der Pumpe.The size of a delivery volume on the inlet side or in section 62 determines a theoretical pumping speed of the screw pump 10. The slope of the screw profile 38, 40 is constant on the inlet side over section 62 so that the delivery volume is only compressed after completion by the internal compression. If a respective rotor 28, 30 closes a respective delivery volume too early or too late or the internal compression begins too early, the theoretical pumping speed of the pump drops.

Die Größe eines jeweiligen Fördervolumens auf der Auslassseite bzw. im Abschnitt 66 bestimmt die Leistungsaufnahme der Pumpe im Betrieb bei einem erreichbaren Enddruck. Das Verhältnis der Größen des Fördervolumens an Einlassseite und Auslasseite bzw. in den Abschnitten 62 und 66 entspricht dem Verhältnis der inneren Verdichtung der Pumpe.The size of a respective delivery volume on the outlet side or in section 66 determines the power consumption of the pump during operation at an achievable final pressure. The ratio of the sizes of the delivery volume on the inlet side and outlet side or in sections 62 and 66 corresponds to the ratio of the internal compression of the pump.

In Abschnitt 66 ist die Steigung über mehrere Umdrehungen des Schraubenprofils 38, 40 konstant. Die Steigung entspricht dabei in etwa dem Minimum der durch ein bestimmtes Bearbeitungswerkzeug erreichbaren Steigung und ist somit, insbesondere unter Kostenabwägung, fertigungstechnisch bedingt. Dadurch, dass mehrere Umdrehungen, also mehrere abgeschlossene Fördervolumina, im Abschnitt 66 vorgesehen sind, wird eine Rückströmung infolge einer Druckdifferenz zwischen den Spalten ausgeglichen. Insgesamt bestimmen insbesondere der gesamte Steigungsverlauf entlang der Rotoren 28, 30 und die Größe der sich zwischen den Rotoren 28, 30 und zwischen Rotoren 28, 30 und dem Gehäuse 16 ausbildenden Spalte die vakuumtechnischen Leistungsdaten der Pumpe, also insbesondere das Saugvermögen und einen erreichbaren Enddruck.In section 66 the slope is constant over several revolutions of the screw profile 38, 40. The slope corresponds approximately to the minimum of the slope that can be achieved by a specific machining tool and is therefore, in particular under cost consideration, due to manufacturing technology. Because several revolutions, that is to say several closed delivery volumes, are provided in section 66, a backflow due to a pressure difference between the gaps is compensated for. Overall, the entire gradient along the rotors 28, 30 and the size of the gaps formed between the rotors 28, 30 and between rotors 28, 30 and the housing 16 determine the vacuum performance data of the pump, i.e. in particular the pumping speed and an achievable final pressure.

Die Schraubenprofile 38, 40 weisen durch ihre zweigängige Ausgestaltung eine besonders geringe Unwucht auf. Es sind also beispielsweise keine Ausgleichselemente, wie z.B. Ausgleichsmassen, die zusätzlichen Bauraum erfordern, und/oder Ausgleichsbohrungen, in denen sich Material ablagern kann, notwendig. Die Pumpe kann mit den zweigängigen Zykloidenschraubenprofilen 38, 40 in einem weiten Drehzahlbereich, insbesondere mit Drehzahlregelung, und/oder beispielsweise in einer Stand-By-Betriebsart betrieben werden.The screw profiles 38, 40 have a particularly low imbalance due to their two-thread design. For example, no compensation elements, such as compensation weights, which require additional installation space, and / or compensation bores in which material can be deposited are necessary. The pump can be operated with the double-thread cycloid screw profiles 38, 40 in a wide speed range, in particular with speed control, and / or, for example, in a stand-by mode.

Die Verdichtung des Prozessgases im Allgemeinen erzeugt Wärme, die bei der Schraubenpumpe 10 vornehmlich durch eine Flüssigkeitskühlung abgeführt wird. In Fig. 4 sind die hierfür vorgesehenen Nuten 32 sichtbar. Kühlleitungen der Flüssigkeitskühlung erstrecken sich hier und vorzugsweise in Längsrichtung über einen weiten Bereich der Schraubenprofile, insbesondere über wenigstens die Hälfte der Länge der Schraubenprofile. Insbesondere ist die Flüssigkeitskühlung im Bereich oder in der Nähe einer inneren Verdichtung angeordnet.The compression of the process gas generally generates heat which, in the case of the screw pump 10, is primarily dissipated by a liquid cooling system. In Fig. 4 the grooves 32 provided for this purpose are visible. Cooling lines of the liquid cooling extend here and preferably in the longitudinal direction over a wide area of the screw profiles, in particular over at least half the length of the screw profiles. In particular, the liquid cooling is arranged in the area or in the vicinity of an internal compression.

An einem einlassseitigen Ende des Gehäuses 16 ist der Lagerschild 18 befestigt. Dieser trägt unter anderem eine weitere Lagerung mit Lagern 68, die eine Loslagerung bilden. Im Gegensatz zu einem gegenüberliegenden, an einem auslassseitigen Gehäuseende angeordneten Lagerschild 70, der integral mit dem Gehäuse 16 ausgebildet ist aber auch separat ausgebildet sein kann, ist der Lagerschild 68 als separates Bauteil ausgebildet, kann jedoch auch integral ausgebildet sein.The end shield 18 is attached to an inlet-side end of the housing 16. This carries, among other things, a further bearing with bearings 68, which form a floating bearing. In contrast to an opposite end shield 70, which is arranged at an outlet-side end of the housing and is integral with the housing 16 is formed but can also be formed separately, the bearing plate 68 is formed as a separate component, but can also be formed integrally.

Einlassseitig sind ebenfalls Spritzscheiben 54, Deflektoren 58 und ein Kolbenringträger 60 mit mehreren Kolbenringen vorgesehen, die entsprechend der auslassseitigen Anordung arbeiten. Einlassseitig ist ein weiteres, separat ausgeführtes Ölbad im Deckel 20 vorgesehen. Auch für dieses Ölbad ist ein Tauchkühler 34 vorgesehen. Alternativ oder zusätzlich kann auch beispielsweise eine Kühlleitung in einer Wand des Lagerschildes 14 und/oder des Deckels 20 vorgesehen, insbesondere vergossen seinOn the inlet side, injection disks 54, deflectors 58 and a piston ring carrier 60 with a plurality of piston rings are also provided, which operate in accordance with the arrangement on the outlet side. On the inlet side, a further, separately designed oil bath is provided in the cover 20. An immersion cooler 34 is also provided for this oil bath. Alternatively or additionally, for example, a cooling line can also be provided, in particular encapsulated, in a wall of the bearing plate 14 and / or the cover 20

Am Anfang eines Abpumpvorganges durch die Pumpe 10 herrscht gewöhnlich am Einlass 22 im Wesentlichen der gleiche Druck wie am Auslass. Während des Abpumpens sinkt dagegen der Druck am Einlass 22 bis hin zu einem Enddruck, der hinsichtlich resultierender Kräfte im Wesentlichen Null ist. Somit übt der Druck am Auslass 24 eine Kraft auf die Rotoren 28, 30 aus, die anders ist als am Anfang des Abpumpvorgangs. Um diese Kraft auszugleichen kann z.B. eine Vorspanneinrichtung, insbesondere eine Feder, vorgesehen sein, die insbesondere bei einem Loslager des Rotors und/oder einlassseitig vorgesehen ist. Die Vorspanneinrichtung kann beispielsweise auch durch schräg verzahnte Zahnräder auf die Rotoren wirkende Kräfte aufnehmen und/oder generell eine auslegungsgerechte Vorspannung der Lager unabhängig vom Betriebszustand bei sich verändernden Drücken bzw. Druckverhältnissen gewährleisten.At the beginning of a pumping process by the pump 10, the pressure at the inlet 22 is usually essentially the same as at the outlet. During the pumping-out, however, the pressure at the inlet 22 drops to an end pressure which is essentially zero in terms of the resulting forces. The pressure at the outlet 24 thus exerts a force on the rotors 28, 30 that is different than at the beginning of the pumping-out process. To compensate for this force, a pretensioning device, in particular a spring, can be provided, for example, which is provided in particular in the case of a floating bearing of the rotor and / or on the inlet side. The preloading device can, for example, also absorb forces acting on the rotors by means of helically toothed gears and / or generally guarantee a design-appropriate preloading of the bearings regardless of the operating state with changing pressures or pressure conditions.

In Fig. 5 ist ein Tauchkühler 34 dargestellt, wie er im Getriebekasten 14 bzw. im Deckel 20 der Schraubenvakuumpumpe 10 angeordnet ist. In dieser Ausführungsform sind die Tauchkühler 34 also identisch ausgebildet, was zu einer geringen Teilevielfalt und geringen Herstellungskosten führt.In Fig. 5 an immersion cooler 34 is shown as it is arranged in the gear box 14 or in the cover 20 of the screw vacuum pump 10. In this embodiment, the immersion coolers 34 are designed identically, which leads to a low number of parts and low manufacturing costs.

Der Tauchkühler 34 weist eine Kühlleitung 72 auf, die durch einen Kühlkörper 74 verläuft. Der Kühlkörper weist eine Strukturierung zur Erhöhung der Oberfläche des Kühlkörpers auf, um die Wärmeübertragung zu optimieren. Der Tauchkühler 34 weist außerdem einen Flansch 76 auf, mit dem der Tauchkühler 34 befestigt wird.The immersion cooler 34 has a cooling line 72 which runs through a heat sink 74. The heat sink has a structure to increase the surface area of the heat sink in order to optimize the heat transfer. The immersion cooler 34 also has a flange 76 with which the immersion cooler 34 is fastened.

BezugszeichenlisteList of reference symbols

1010
SchraubenvakuumpumpeScrew vacuum pump
1212th
Motorengine
1414th
GetriebekastenGear box
1616
Gehäusecasing
1818th
LagerschildBearing shield
2020th
Deckelcover
2222nd
Einlassinlet
2424
AuslassOutlet
2626th
KühlleitungCooling pipe
2828
SchraubenrotorScrew rotor
3030th
SchraubenrotorScrew rotor
3232
NutGroove
3434
TauchkühlerImmersion cooler
3636
TaillierungSidecut
3838
SchraubenprofilScrew profile
4040
SchraubenprofilScrew profile
4242
SynchronisierungsgetriebeSynchronization gear
4343
Zahnradgear
4444
Gehäusecasing
4646
Statorstator
4848
MagnetträgerMagnet carrier
5050
VergusskörperPotting body
5252
Platinecircuit board
5454
SpritzscheibeSplash screen
5656
Lagerwarehouse
5858
DeflektorDeflector
6060
KolbenringträgerPiston ring carrier
6262
erster Abschnittfirst section
6363
SchraubenachseScrew axis
6464
zweiter Abschnittsecond part
6666
dritter Abschnittthird section
6767
AnsaugbereichSuction area
6868
Lagerwarehouse
7070
LagerschildBearing shield
7272
KühlleitungCooling pipe
7474
KühlkörperHeat sink
7676
Flanschflange

Claims (14)

  1. A screw vacuum pump (10) comprising
    a housing (16);
    two screw rotors (28, 30) which are arranged in the housing (16), which are in engagement with one another and which, for the conveying of a process gas, repeatedly form closed conveying volumes of the process gas in cooperation with the housing (16) and convey them in the direction of an outlet (24); and
    a motor (12) which is configured as a direct drive for one of the screw rotors (28),
    wherein an active liquid cooling is provided both for the screw rotors (28, 30) and for the motor (12),
    characterized in that
    a shield which is formed as a waisting (36) of the housing is arranged between at least one heat source and a heat-sensitive region.
  2. A screw vacuum pump (10) in accordance with claim 1,
    characterized in that
    the directly driven screw rotor (28) forms a rotor of the motor (12).
  3. A screw vacuum pump (10) in accordance with claim 1 or claim 2,
    characterized in that
    the motor (12) is configured as a permanent magnet synchronous machine, in particular comprising inwardly disposed magnets.
  4. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    a frequency converter is provided for the motor (12).
  5. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the screw rotors (28, 30) each have at least two sections (62, 64) which are adjacent along the screw axis (63),
    with the screw rotors (28, 30) each having an at least substantially constant pitch in a first section (62) disposed closer to an inlet (22) and a lower pitch in a second section (64) than in the first section (62), and
    with the first section (62) being longer with respect to the screw axis (63) than a closed conveying volume in the first section (62).
  6. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    a pressure relief valve is provided in the region of an inner compression of the pump (10) and is connected to an outlet (24) of the pump (10) or forms an outlet (24).
  7. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the pump (10) has a control device which is configured and/or adapted to operate the pump (10) at least in a normal operating mode at a rotor rotary speed of approximately 120 Hz or less, in particular of approximately 120 Hz or less and of approximately 80 Hz or more.
  8. A screw vacuum pump (10) in accordance with claim 7,
    characterized in that
    the control device is configured and/or adapted to operate the pump (10) at times at least in an amplifying operating mode in which the rotor rotary speed is higher than in the normal operating mode.
  9. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    a contactless seal, in particular at least one piston ring, is provided for at least one of the screw rotors (28, 30).
  10. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the screw rotors (28, 30) are coupled via a synchronization gear (42), with the synchronization gear (42) having a straight tooth arrangement.
  11. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the pump (10) is configured such that at least one heat source is arranged in the vicinity of at least one heat sink.
  12. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the waisting (36) is provided between an outlet (24) and a bearing section (58) for the screw rotors (28, 30).
  13. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the liquid cooling is configured such that it forms a turbulent flow in the region of a heat source.
  14. A screw vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the screw rotors are formed by a cycloidal profile, in particular a two-start cycloidal profile.
EP17207576.4A 2017-12-15 2017-12-15 Screw vacuum pump Active EP3499039B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP17207576.4A EP3499039B1 (en) 2017-12-15 2017-12-15 Screw vacuum pump
JP2018232381A JP7221672B2 (en) 2017-12-15 2018-12-12 screw vacuum pump

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP17207576.4A EP3499039B1 (en) 2017-12-15 2017-12-15 Screw vacuum pump

Publications (2)

Publication Number Publication Date
EP3499039A1 EP3499039A1 (en) 2019-06-19
EP3499039B1 true EP3499039B1 (en) 2021-03-31

Family

ID=60673648

Family Applications (1)

Application Number Title Priority Date Filing Date
EP17207576.4A Active EP3499039B1 (en) 2017-12-15 2017-12-15 Screw vacuum pump

Country Status (2)

Country Link
EP (1) EP3499039B1 (en)
JP (1) JP7221672B2 (en)

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09308183A (en) * 1996-05-16 1997-11-28 Matsushita Electric Ind Co Ltd Liquid-cooled motor frame
DE19745616A1 (en) 1997-10-10 1999-04-15 Leybold Vakuum Gmbh Cooling system for helical vacuum pump
DE19745615A1 (en) * 1997-10-10 1999-04-15 Leybold Vakuum Gmbh Screw vacuum pump with rotors
DE10156179A1 (en) 2001-11-15 2003-05-28 Leybold Vakuum Gmbh Cooling a screw vacuum pump
JP2004350466A (en) 2003-05-26 2004-12-09 Kobe Steel Ltd Liquid-cooled motor
GB0502149D0 (en) * 2005-02-02 2005-03-09 Boc Group Inc Method of operating a pumping system
JP2008038764A (en) * 2006-08-07 2008-02-21 Shimadzu Corp Turbo-molecular pump and power source device therefor
DE102010061202A1 (en) * 2010-12-14 2012-06-14 Gebr. Becker Gmbh vacuum pump
DE202016005209U1 (en) * 2016-08-30 2017-12-01 Leybold Gmbh Screw vacuum pump

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
EP3499039A1 (en) 2019-06-19
JP7221672B2 (en) 2023-02-14
JP2019113064A (en) 2019-07-11

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