EP4212730A1 - Pompe à vide avec étage de pompage de holward optimisé pour compenser la perte de performance liée à la température - Google Patents

Pompe à vide avec étage de pompage de holward optimisé pour compenser la perte de performance liée à la température Download PDF

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Publication number
EP4212730A1
EP4212730A1 EP23175631.3A EP23175631A EP4212730A1 EP 4212730 A1 EP4212730 A1 EP 4212730A1 EP 23175631 A EP23175631 A EP 23175631A EP 4212730 A1 EP4212730 A1 EP 4212730A1
Authority
EP
European Patent Office
Prior art keywords
holweck
stator sleeve
sleeve
vacuum pump
free end
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.)
Pending
Application number
EP23175631.3A
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German (de)
English (en)
Inventor
Erfindernennung liegt noch nicht vor Die
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 Technology AG
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Pfeiffer Vacuum Technology AG
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Filing date
Publication date
Application filed by Pfeiffer Vacuum Technology AG filed Critical Pfeiffer Vacuum Technology AG
Publication of EP4212730A1 publication Critical patent/EP4212730A1/fr
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/52—Casings; Connections of working fluid for axial pumps
    • F04D29/54—Fluid-guiding means, e.g. diffusers
    • F04D29/541—Specially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F04D19/044—Holweck-type pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/60—Mounting; Assembling; Disassembling
    • F04D29/64—Mounting; Assembling; Disassembling of axial pumps
    • F04D29/642—Mounting; Assembling; Disassembling of axial pumps by adjusting the clearances between rotary and stationary parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/20—Three-dimensional
    • F05D2250/29—Three-dimensional machined; miscellaneous
    • F05D2250/292—Three-dimensional machined; miscellaneous tapered

Definitions

  • the present invention relates to a vacuum pump, also referred to here only as a pump, in particular a turbomolecular pump, according to the preamble of claim 1 with at least one Holweck pump stage, which comprises a Holweck rotor and a Holweck stator, the Holweck rotor having a rotor shaft a hub provided thereon and at least one Holweck rotor sleeve provided on the hub, which concentrically surrounds the rotor shaft, and wherein the Holweck stator comprises a Holweck stator sleeve arranged concentrically to the Holweck rotor sleeve, which has a fixed housing section of the vacuum pump fixed end, a free end axially opposite to the fixed end, and an inner surface having internal threads formed thereon and an outer surface having external threads formed thereon.
  • Vacuum pumps are used in various areas of technology. Depending on the requirements, the vacuum pumps have one or more pump stages.
  • Holweck pump stages belong to the category of molecular vacuum pumps and, by rotating a Holweck rotor relative to a stationary Holweck stator, generate a molecular flow which leads to heating of the vacuum pump during operation.
  • a vacuum pump can comprise one or more Holweck stages, it being possible for a number of Holweck stages to be operated both in series and in parallel with one another.
  • Holweck stages are used in turbomolecular vacuum pumps used and one or more turbomolecular pump stages downstream in the direction of flow.
  • a Holweck stage comprises a Holweck rotor and a Holweck stator, the Holweck rotor having a rotor shaft to which one or more Holweck rotor sleeves are concentrically attached by means of a Holweck hub, for example in the form of a disk.
  • the Holweck stator is provided with a single or multi-start Holweck thread. The gas molecules to be pumped are pumped by the rotating movement of the Holweck rotor relative to the Holweck stator along the thread turns from an inlet to an outlet of the respective Holweck pump stage.
  • a thread includes a helically circumferential Holweck channel delimited by the walls of a web, in which the gas molecules are conveyed when the rotor sleeve rotates relative to the stator sleeve.
  • the width of the radial Holweck gap between the web or thread tips and the rotor sleeve should be kept as small as possible.
  • Holweck arrangements in which several Holweck stages are nested concentrically one inside the other, so that the pumping directions of Holweck stages that follow one another radially are opposite to one another.
  • Two Holweck stages that follow one another in the flow direction, a (radially) outer Holweck stage and a (radially) inner Holweck stage can thus comprise a common Holweck stator, which is provided with a Holweck thread on both sides and is located between two rotor sleeves .
  • the Holweck stator comprises a fixed end attached to a stationary housing section of the vacuum pump, for example by a press fit, a free end opposite the fixed end in the axial direction near the A rotor hub and an inner surface having internal threads formed thereon and an outer surface having external threads formed thereon. Due to the small cross-sectional area of the Holweck stator, a comparatively high temperature difference is required within the Holweck stator in order to dissipate the amount of heat introduced. This creates a temperature profile with the highest temperature at the free end.
  • the heating of the Holweck stator sleeve results in the Holweck stator sleeve increasingly expanding in the radial direction towards its free end, so that the Holweck gap, starting from the fixed end towards the free end of the Holweck stator sleeve, increasingly deviates from its target - or nominal diameter deviates. This in turn has the consequence that the pumping speed and thus the pumping capacity of the vacuum pump decreases in an undesired manner during pumping operation.
  • the invention is therefore based on the object of specifying a solution to the problem described above, according to which the pumping capacity of a vacuum pump with a Holweck pump stage decreases due to temperature-related deformations of the Holweck stator or the Holweck stator sleeve.
  • the invention is intended to ensure that the pumping speed of a vacuum pump, for which it is designed, is also achieved under operating conditions at elevated temperatures.
  • a vacuum pump having the features of claim 1 and in particular in that when the vacuum pump is cold at room temperature the internal thread at the free end of the Holweck stator sleeve has a smaller nominal internal diameter than at the free end of the Holweck stator sleeve and that in a corresponding Also point out the external thread in the cold condition of the vacuum pump at room temperature at the free end of the Holweck stator sleeve has a smaller nominal outside diameter than at the fixed end of the Holweck stator sleeve.
  • the vacuum pump is in a cold state
  • this is to be understood as meaning the temperature of the vacuum pump which it has in the permanently switched-off operating state at a room temperature of around 20°C.
  • the vacuum pump and in particular the Holweck stator sleeve has a temperature of the order of about 20°C.
  • the vacuum pump is in a stationary state at operating temperature or in a thermally steady state, this state refers to a temperature of the vacuum pump that it achieves when it is continuously operated at its rated speed.
  • the Holweck stator sleeve in the manner according to the invention has a nominal inside or nominal outside diameter at its free end - measured between the web or thread tips of the internal thread or the external thread - and thus the Holweck stator sleeve at its free end has smaller inner and outer circumferences than at its fixed end, the Holweck stator sleeve can thus expand in the radial direction during operation at the free end due to temperature until the inner and/or outer Holweck gap has the desired shape.
  • the Holweck stator sleeve thus has a shape in the cold state that deviates from the desired shape of the Holweck stator sleeve to achieve a desired Holweck gap.
  • the Holweck stator sleeve can thus deform due to temperature in such a way that in the desired Holweck gap is set when the vacuum pump is stationary at operating temperature.
  • the hub is fastened to the rotor shaft and the Holweck rotor sleeve is fastened to the hub.
  • the hub and the rotor shaft are therefore parts that can be handled separately and are connected to one another in a detachable or non-detachable manner during assembly of the vacuum pump.
  • the hub and the Holweck rotor sleeve are parts that can be handled separately and are only connected to one another in a detachable or non-detachable manner during assembly of the vacuum pump.
  • the hub is formed integrally with the rotor shaft, whereas the Holweck rotor sleeve is attached to the hub, or that the Holweck rotor sleeve is formed integrally with the hub and the hub on the rotor shaft is attached.
  • the Holweck stator is designed as a double-sided Holweck stator with an internally and externally threaded Holweck stator sleeve
  • the Holweck rotor consequently has an inner and an outer Holweck rotor sleeve, both of which concentrically surround the rotor shaft, with the outer Holweck rotor sleeve concentrically surrounds the Holweck stator sleeve and the Holweck stator sleeve concentrically surrounds the inner Holweck rotor sleeve.
  • the inner Holweck rotor sleeve thus forms, together with the internal thread of the Holweck stator sleeve, a inner Holweck pumping stage, whereas the outer Holweck rotor sleeve together with the external thread of the Holweck stator sleeve forms an outer Holweck pumping stage.
  • the shape of the Holweck gap of both the inner Holweck pump stage and the outer Holweck pump stage deviates from the desired shape of the respective Holweck gap.
  • the Holweck stator sleeve can expand in the radial direction during operation of the vacuum pump at its free end due to temperature, so that both the inside and the outer Holweck pump stage also has a Holweck gap in the thermally steady state, which at least comes close to the desired shape.
  • the inside diameter of the internal thread of the Holweck stator sleeve can gradually decrease in the direction of its free end; According to a preferred embodiment, however, it can be provided that when the vacuum pump is cold, the nominal inside diameter of the internal thread of the Holweck stator sleeve decreases continuously or steadily in the direction of its free end.
  • the nominal inside diameter of the internal threads may decrease linearly or according to a concave curvature function as it approaches the free end of the Holweck stator sleeve.
  • the nominal outside diameter of the external thread of the Holweck stator sleeve can decrease in steps or continuously in the direction of its free end, with the latter case the nominal outside diameter linearly or according to a function with increasing approach to the free end of the Holweck stator sleeve convex curvature can decrease.
  • the nominal inside diameter and the nominal outside diameter decrease progressively or monotonically in the direction of the free end of the Holweck stator sleeve, which means that the Holweck stator sleeve at its free end has the smallest nominal inner and outer diameter.
  • the Holweck stator has the highest temperature at its free end for operational reasons, which is why the greatest thermally induced expansion is present there. Accordingly, the free end of the Holweck stator sleeve has both the smallest nominal inside diameter and the smallest nominal outside diameter, as a result of which the temperature-related deformation of the Holweck stator can be compensated for to a certain extent.
  • the nominal outside diameter of the external thread of the Holweck stator sleeve decreases in the direction of the free end of the Holweck stator sleeve in such a way that when the vacuum pump is at operating temperature and stationary, there is a radial Holweck gap between of the Holweck rotor sleeve and the external thread and in particular the thread crests of the external thread which has a substantially constant width between the fixed end and the free end of the Holweck stator sleeve.
  • the nominal inner diameter of the internal thread of the Holweck stator sleeve decreases in the direction of the free end of the Holweck stator sleeve in such a way that in the stationary state at operating temperature or in the thermally settled state State of the vacuum pump, a radial Holweck gap between the Holweck rotor sleeve and the internal thread, in particular the thread crests of the internal thread, which has a substantially constant width between the fixed end and the free end of the Holweck stator sleeve.
  • both the nominal inside diameter and the nominal outside diameter of the inside and outside threads of the Holweck stator sleeve are in the previously decrease steadily in the manner described in the direction of the free end of the Holweck stator sleeve.
  • the temperature of the Holweck stator sleeve also increases steadily during operation in the direction of its free end, with the highest temperature being at its free end.
  • the decrease in the nominal inside and nominal outside diameters in the direction of the free end of the Holweck stator sleeve thus follows the temperature profile of the Holweck stator sleeve in the direction of its free end, so to speak, whereby the temperature-related expansion of the Holweck stator sleeve can be compensated for in a targeted manner in such a way that the Holweck gap both the inner and the outer Holweck pump stage has a substantially constant size in the stationary state at operating temperature.
  • the internal thread of the Holweck stator sleeve has a constant thread depth between its fixed end and its free end when the vacuum pump is cold, and that the internal surface of the Holweck stator sleeve, which forms the groove base of the internal thread, defines a core inner diameter of the internal thread, which decreases in the cold state of the vacuum pump in the direction of the free end of the Holweck stator sleeve.
  • the external thread of the Holweck stator sleeve has a constant thread depth between its fixed end and its free end when the vacuum pump is cold and that the outer surface of the Holweck stator sleeve, which is the root of the thread of the External thread forms, defines a core outer diameter of the external thread, which decreases in the cold state of the vacuum pump in the direction of the free end of the Holweck stator sleeve.
  • the Holweck stator sleeve has a wall thickness that is constant between the fixed end and the free end of the Holweck stator sleeve, provided that the inner and outer core diameters of the inner and .Take off the male threads equally or at the same rate towards the free end of the Holweck stator sleeve.
  • the Holweck stator sleeve can have a wall thickness which decreases in the direction of the free end of the Holweck stator sleeve, for example continuously or stepwise, in which case either the outer core diameter is greater than the inner core diameter in the direction of the free end of the Holweck Stator sleeve decreases or the core outer diameter decreases more than the core inner diameter towards the free end of the Holweck stator sleeve.
  • the inner surface of the Holweck stator sleeve defines a core inner diameter of the internal thread, which in the cold state of the vacuum pump is between the fixed end and the free end end of the Holweck stator sleeve is constant, in which case the internal thread has a thread depth which increases towards the free end of the Holweck stator sleeve, which means that the inner diameter of the internal thread towards the free end of the Holweck stator sleeve in the desired way decreases.
  • the outer surface of the Holweck stator sleeve defines a core outer diameter of the external thread which, in the cold state of the vacuum pump, is between the fixed end and the free end of the Holweck stator sleeve is constant, in which case the external thread has a thread depth which decreases towards the free end of the Holweck stator sleeve, so that the outer diameter of the external thread towards the free end of the Holweck stator sleeve decreases in the desired way.
  • the turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a recipient, not shown, can be connected in a manner known per se.
  • the gas from the recipient can be sucked out of the recipient via the pump inlet 115 and conveyed through the pump to a pump outlet 117 to which a backing pump, such as a rotary vane pump, can be connected.
  • the inlet flange 113 forms when the vacuum pump is aligned according to FIG 1 the upper end of the housing 119 of the vacuum pump 111.
  • the housing 119 comprises a lower part 121 on which an electronics housing 123 is arranged laterally. Electrical and/or electronic components of the vacuum pump 111 are accommodated in the electronics housing 123, for example for operating an electric motor 125 arranged in the vacuum pump (cf. also 3 ). Several connections 127 for accessories are provided on the electronics housing 123 .
  • a data interface 129 for example according to the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.
  • turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.
  • a flood inlet 133 in particular in the form of a flood valve, is provided on the housing 119 of the turbomolecular pump 111, via which the vacuum pump 111 can be flooded.
  • a sealing gas connection 135, which is also referred to as a flushing gas connection through which flushing gas to protect the electric motor 125 (see e.g 3 ) before the pumped gas in the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111, can be admitted.
  • Two coolant connections 139 are also arranged in the lower part 121, one of the coolant connections being provided as an inlet and the other coolant connection being provided as an outlet for coolant, which can be conducted into the vacuum pump for cooling purposes.
  • Other existing turbomolecular vacuum pumps (not shown) operate solely on air cooling.
  • the lower side 141 of the vacuum pump can serve as a standing surface, so that the vacuum pump 111 can be operated standing on the underside 141 .
  • the vacuum pump 111 can also have the inlet flange 113 on one Recipients are attached and are thus operated to a certain extent suspended.
  • the vacuum pump 111 can be designed in such a way that it can also be operated when it is oriented in a different way than in FIG 1 is shown. It is also possible to realize embodiments of the vacuum pump in which the underside 141 cannot be arranged facing downwards but to the side or directed upwards. In principle, any angles are possible.
  • various screws 143 are also arranged, by means of which components of the vacuum pump that are not further specified here are fastened to one another.
  • a bearing cap 145 is attached to the underside 141 .
  • Attachment bores 147 are also arranged on the underside 141, via which the pump 111 can be attached to a support surface, for example. This is not possible with other existing turbomolecular vacuum pumps (not shown), which in particular are larger than the pump shown here.
  • a coolant line 148 is shown, in which the coolant fed in and out via the coolant connections 139 can circulate.
  • the vacuum pump comprises several process gas pump stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.
  • a rotor 149 is arranged in the housing 119 and has a rotor shaft 153 which can be rotated about an axis of rotation 151 .
  • the turbomolecular pump 111 comprises a plurality of turbomolecular pumping stages connected in series with one another in a pumping manner, with a plurality of radial rotor disks 155 fastened to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119.
  • a rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular pump stage.
  • the stator discs 157 are held at a desired axial distance from one another by spacer rings 159 .
  • the vacuum pump also comprises Holweck pump stages which are arranged one inside the other in the radial direction and are connected in series with one another for pumping purposes. There are other turbomolecular vacuum pumps (not shown) that do not have Holweck pumping stages.
  • the rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two Holweck rotor sleeves 163, 165 in the shape of a cylinder jacket, fastened to the rotor hub 161 and carried by it, which are oriented coaxially to the axis of rotation 151 and are nested in one another in the radial direction. Also provided are two cylinder jacket-shaped Holweck stator sleeves 167, 169, which are also oriented coaxially with respect to the axis of rotation 151 and are nested in one another when viewed in the radial direction.
  • the active pumping surfaces of the Holweck pump stages are formed by the lateral surfaces, ie by the radial inner and/or outer surfaces, of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169.
  • the radially inner surface of the outer Holweck stator sleeve 167 abuts the radially outer surface of the outer Holweck rotor sleeve 163 forming a radial Holweck gap 171 and forms the first Holweck pump stage following the turbomolecular pumps.
  • the radially inner surface of the outer Holweck rotor sleeve 163 faces the radially outer surface of the inner Holweck stator sleeve 169 to form a radial Holweck gap 173 and therewith forms a second Holweck pumping stage.
  • the radially inner surface of the inner Holweck stator sleeve 169 faces the radially outer surface of the inner Holweck rotor sleeve 165 to form a radial Holweck gap 175 and therewith forms the third Holweck pumping stage.
  • a radially running channel can be provided, via which the radially outer Holweck gap 171 is connected to the middle Holweck gap 173.
  • a radially extending channel can be provided at the upper end of the inner Holweck stator sleeve 169, via which the middle Holweck gap 173 is connected to the radially inner Holweck gap 175.
  • a connecting channel 179 to the outlet 117 can be provided at the lower end of the radially inner Holweck rotor sleeve 165 .
  • the above-mentioned pumping-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves running in a spiral shape around the axis of rotation 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and the gas for operating the Advance vacuum pump 111 in the Holweck grooves.
  • a roller bearing 181 in the region of the pump outlet 117 and a permanent magnet bearing 183 in the region of the pump inlet 115 are provided for the rotatable mounting of the rotor shaft 153 .
  • a conical injection nut 185 is provided on the rotor shaft 153 with an outer diameter that increases toward the roller bearing 181 .
  • the injection nut 185 is in sliding contact with at least one stripper of an operating fluid store.
  • an injection screw may be provided instead of an injection nut. Since different designs are thus possible, the term "spray tip" is also used in this context.
  • the resource reservoir comprises a plurality of absorbent disks 187 stacked on top of one another, which are impregnated with a resource for the roller bearing 181, e.g. with a lubricant.
  • the operating fluid is transferred by capillary action from the operating fluid reservoir via the scraper to the rotating spray nut 185 and, as a result of the centrifugal force, is conveyed along the spray nut 185 in the direction of the increasing outer diameter of the spray nut 185 to the roller bearing 181, where it e.g. fulfills a lubricating function.
  • the roller bearing 181 and the operating fluid reservoir are surrounded by a trough-shaped insert 189 and the bearing cover 145 in the vacuum pump.
  • the permanent magnet bearing 183 comprises a bearing half 191 on the rotor side and a bearing half 193 on the stator side, which each comprise a ring stack of a plurality of permanent magnetic rings 195, 197 stacked on top of one another in the axial direction.
  • the ring magnets 195, 197 lie opposite one another, forming a radial bearing gap 199, the ring magnets 195 on the rotor side being arranged radially on the outside and the ring magnets 197 on the stator side being arranged radially on the inside.
  • the magnetic field present in the bearing gap 199 causes magnetic repulsion forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be supported radially.
  • the rotor-side ring magnets 195 are carried by a support portion 201 of the rotor shaft 153, which Ring magnets 195 surrounds radially on the outside.
  • the ring magnets 197 on the stator side are carried by a support section 203 on the stator side, which extends through the ring magnets 197 and is suspended on radial struts 205 of the housing 119 .
  • the ring magnets 195 on the rotor side are fixed parallel to the axis of rotation 151 by a cover element 207 coupled to the carrier section 201 .
  • the ring magnets 197 on the stator side are fixed parallel to the axis of rotation 151 in one direction by a fastening ring 209 connected to the support section 203 and a fastening ring 211 connected to the support section 203 .
  • a disc spring 213 can also be provided between the fastening ring 211 and the ring magnet 197 .
  • An emergency or safety bearing 215 is provided within the magnetic bearing, which runs idle without contact during normal operation of the vacuum pump 111 and only engages in the event of an excessive radial deflection of the rotor 149 relative to the stator, in order to create a radial stop for the rotor 149 to form, so that a collision of the rotor-side structures is prevented with the stator-side structures.
  • the backup bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and/or the stator, which causes the backup bearing 215 to be disengaged during normal pumping operation.
  • the radial deflection at which the backup bearing 215 engages is dimensioned large enough so that the backup bearing 215 does not engage during normal operation of the vacuum pump, and at the same time small enough so that the rotor-side structures collide with the stator-side structures under all circumstances is prevented.
  • the vacuum pump 111 includes the electric motor 125 for rotating the rotor 149.
  • the armature of the electric motor 125 is formed by the rotor 149, whose rotor shaft 153 extends through the motor stator 217 therethrough.
  • On the through the motor stator 217 extending portion of the Rotor shaft 153 can be arranged radially on the outside or embedded in a permanent magnet arrangement.
  • the motor stator 217 is fixed in the housing inside the motor room 137 provided for the electric motor 125 .
  • a sealing gas which is also referred to as flushing gas and which can be air or nitrogen, for example, can reach the engine compartment 137 via the sealing gas connection 135 .
  • the sealing gas can protect the electric motor 125 from process gas, e.g. from corrosive components of the process gas.
  • the engine compartment 137 can also be evacuated via the pump outlet 117, i.e. the vacuum pressure produced by the backing pump connected to the pump outlet 117 prevails in the engine compartment 137 at least approximately.
  • a labyrinth seal 223, known per se, can also be provided between the rotor hub 161 and a wall 221 delimiting the motor compartment 137, in particular in order to achieve better sealing of the motor compartment 217 in relation to the Holweck pump stages located radially outside.
  • Holweck pump stages 10 designed according to the invention are described, which can be installed in the turbomolecular vacuum pump 111 instead of the previously described Holweck pump stage, although the rest of the structure of the turbomolecular vacuum pump 111 and also the basic structure of the Holweck pump stage with three nested Pump stages, which are hereinafter also referred to generically as a single "Holweck pump stage", can be retained.
  • the Holweck pump stage 10 shown there has essentially the same structure as the Holweck pump stage with reference to FIG Figures 1 to 5 described vacuum pump 111.
  • the Holweck pump stage 10 also has a rotor hub 161 arranged on the rotor shaft 153 and two rotor sleeves 163, 165 in the shape of a cylinder jacket which are fastened to the rotor hub 161 and carried by it, which are oriented coaxially to the axis of rotation 151 and are nested in one another in the radial direction.
  • two cylinder jacket-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and are nested in one another as seen in the radial direction.
  • the outer Holweck stator sleeve 167 together with the outer Holweck rotor sleeve 163 thus forms a first or outer Holweck pump stage.
  • the structure shown is consistent with that as previously referred to with reference to the Figures 3 to 5 was described.
  • Holweck stator sleeves 167, 169 of 6 a plurality of Holweck grooves running spirally around the axis of rotation 151 in the axial direction.
  • these grooves are formed by webs 16 formed both on the inner surface 12 and on the outer surface 14 of the stator sleeve 169, which run spirally around the axis of rotation 151 and are indicated here only extremely schematically.
  • the respective nominal inner or Formed nominal outer diameter of the respective thread, whereas the inner and outer surfaces 12, 14 correspond to the core inner or core outer diameter dki, dka of the respective thread 18, 20. Since the respective Holweck gap refers to the distance between the tips of the webs 16 and the pumping surface of the rotor sleeves 163, 165, the envelope surrounding the web or thread tips is shown here and assigned the reference symbol "26". is.
  • the internal thread 18 at the free end 22 of the Holweck stator sleeve 169 has a smaller nominal internal diameter dni than at the fixed end 24 of Holweck stator sleeve 169.
  • the external thread 20 in the cold state also has a smaller nominal outside diameter dna at the free end 22 than at the fixed end 24 of the Holweck stator sleeve 169, to which it is attached to a stationary housing section of the vacuum pump 111.
  • the inner and outer surfaces 12, 14 of the stator sleeve 169, on which the inner and outer threads 18, 20 are formed have a conical shape and in particular in the direction of the free end 22 of the Holweck stator sleeve 169 taper steadily.
  • the thread depth of the internal and external threads 18, 20 and the radial dimension of the webs 16 between the fixed end 24 and the free end 22 of the stator sleeve 169 is constant.
  • the Holweck stator sleeve 169 has a wall thickness which is constant between the fixed end 24 and the free end 22 of the Holweck stator sleeve 169 .
  • the Holweck stator sleeve 169 can have a wall thickness which decreases in the direction of the free end 22 of the Holweck stator sleeve 169, although in this case it can also be provided for the thread height of the internal thread to be 18 in Increases in the direction of the free end 22 and/or the thread height of the external thread 20 decreases in the direction of the free end 22 in order to be able to ensure that the internal and external threads at the free end 22 of the Holweck stator sleeve 169 have a smaller nominal inside or nominal outside diameter dni , dna than at the fixed end 24 of the Holweck stator sleeve 169 .
  • the Holweck stator sleeve 169 can thus expand radially during operation of the vacuum pump 111 due to temperature, as is shown in FIG figure 5 is indicated with a dashed line.
  • an internal Holweck gap 175 can thus form between the inner Holweck rotor sleeve 165 and the double-sided Holweck stator sleeve 169, which gap between the fixed end 24 and the free end 22 has a substantially constant size or width. width.
  • an external Holweck gap 173 can occur between the Holweck stator sleeve 169 and the outer rotor sleeve 163, which gap between the fixed end 24 and the free end 22 has a substantially constant size or width.
  • the Holweck stator sleeve 169 does not taper conically towards its free end 22 on the inside and outside; rather it is in the embodiment of 7 provided that the Holweck stator sleeve 169 and in particular its inner and Outer surfaces 12, 14 have a substantially cylindrical shape.
  • the internal and external threads 18, 22 have a smaller nominal internal or nominal external diameter dni, dna than at the fixed end 24, it is in the embodiment of 7 provided that the internal thread 18 has a thread depth which increases in the direction of the free end 22 of the Holweck stator sleeve 169, whereas the external thread 20 has a thread depth which decreases in the direction of the free end 22 of the Holweck stator sleeve 169.
  • the envelope 26 of the Holweck stator sleeve 169 tapers both on the inside and on the outside in the direction of the free end 22 .
  • the stator sleeve 169 can thus expand during operation of the vacuum pump 111 due to the temperature, so that in the thermally steady state, internal and external Holweck gaps 173, 175 can appear, which are between the fixed end 24 and the free end 22 of the Holweck stator sleeve 169 have a substantially constant size.
  • the wall thickness of the Holweck stator sleeve 169 is constant, although it tapers in stages in the direction of the free end 22 of the stator sleeve 169.
  • the thread depth of the internal thread 18 increases in the direction of the free end 22 over the individual stages, before abruptly decreasing at the transition to the next stage.
  • the thread depth of the external thread in the area of the respective step decreases in the direction of the free end 22 before it suddenly increases at the transition to the next step, so that overall the nominal outside diameter dna decreases in the direction of the free end 22 in the desired manner.
  • the embodiments according to the Figures 6, 7 and 8 can also be combined with one another, whereby it can additionally be provided that the wall thickness of the Holweck stator sleeve 169 is not constant without deviating from the concept according to the invention, consequently the nominal inside and nominal outside diameters of the internal and external threads at the free end 22 of the stator sleeve 169 are less than at the fixed end 24 thereof, for which purpose the thread depth of the internal and external threads 18, 20 can vary in the axial direction of the stator sleeve 169 in order to ensure that the envelope 26 regardless of the shape of the inner and outer surfaces 12, 14 both inside and outside to the free end 22 tapers conically.
  • the hub 161 and the rotor shaft 153 are parts that can be handled separately and are only connected to one another in a detachable or non-detachable manner during the assembly of the vacuum pump 111 .
  • the hub 161 and the Holweck rotor sleeves 163, 165 are parts that can be handled separately and are only connected to one another in a detachable or non-detachable manner during assembly of the vacuum pump. This design is particularly suitable for use with medium and large turbomolecular vacuum pumps.
  • the hub 161 is formed integrally with the rotor shaft 153 and that the Holweck rotor sleeves 163, 165 are formed integrally with the hub 161.
  • the Holweck rotor is therefore a single or one-piece part.
  • the rotor shaft 153 is designed integrally with the hub 161, whereas the hub 161 and the Holweck rotor sleeves 163, 165 are parts that can be handled separately and can only be detached from one another during assembly of the vacuum pump or inextricably linked.
  • This embodiment is particularly suitable for use in smaller turbomolecular vacuum pumps.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
EP23175631.3A 2023-01-31 2023-05-26 Pompe à vide avec étage de pompage de holward optimisé pour compenser la perte de performance liée à la température Pending EP4212730A1 (fr)

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EP23154256 2023-01-31

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4273405A1 (fr) * 2023-09-20 2023-11-08 Pfeiffer Vacuum Technology AG Pompe à vide avec un étage de pompage de type holweck avec une géométrie holweck variable

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2730297A (en) * 1950-04-12 1956-01-10 Hartford Nat Bank & Trust Co High-vacuum molecular pump
US20030103842A1 (en) * 2001-12-04 2003-06-05 Manabu Nonaka Vacuum pump
JP2011080407A (ja) * 2009-10-07 2011-04-21 Shimadzu Corp 真空ポンプ
EP2594803A1 (fr) * 2011-11-16 2013-05-22 Pfeiffer Vacuum Gmbh Pompe à vide à friction
EP3657021B1 (fr) * 2018-11-21 2020-11-11 Pfeiffer Vacuum Gmbh Pompe à vide

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2730297A (en) * 1950-04-12 1956-01-10 Hartford Nat Bank & Trust Co High-vacuum molecular pump
US20030103842A1 (en) * 2001-12-04 2003-06-05 Manabu Nonaka Vacuum pump
JP2011080407A (ja) * 2009-10-07 2011-04-21 Shimadzu Corp 真空ポンプ
EP2594803A1 (fr) * 2011-11-16 2013-05-22 Pfeiffer Vacuum Gmbh Pompe à vide à friction
EP3657021B1 (fr) * 2018-11-21 2020-11-11 Pfeiffer Vacuum Gmbh Pompe à vide

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4273405A1 (fr) * 2023-09-20 2023-11-08 Pfeiffer Vacuum Technology AG Pompe à vide avec un étage de pompage de type holweck avec une géométrie holweck variable

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