EP4108930A1 - Pompe à vide dotée d'un support d'aimants réglable dans une direction axiale - Google Patents

Pompe à vide dotée d'un support d'aimants réglable dans une direction axiale Download PDF

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Publication number
EP4108930A1
EP4108930A1 EP22193059.7A EP22193059A EP4108930A1 EP 4108930 A1 EP4108930 A1 EP 4108930A1 EP 22193059 A EP22193059 A EP 22193059A EP 4108930 A1 EP4108930 A1 EP 4108930A1
Authority
EP
European Patent Office
Prior art keywords
holder
magnet carrier
stator
rotor
vacuum pump
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
EP22193059.7A
Other languages
German (de)
English (en)
Inventor
Niklas Wirth
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
Original Assignee
Pfeiffer Vacuum Technology AG
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 Technology AG filed Critical Pfeiffer Vacuum Technology AG
Priority to EP22193059.7A priority Critical patent/EP4108930A1/fr
Publication of EP4108930A1 publication Critical patent/EP4108930A1/fr
Priority to JP2023048032A priority patent/JP2024035041A/ja
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
    • 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
    • F04D19/042—Turbomolecular vacuum 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
    • F04D19/048—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps comprising magnetic bearings
    • 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
    • F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
    • F04D29/056—Bearings
    • F04D29/058—Bearings magnetic; electromagnetic
    • 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
    • F04D29/644—Mounting; Assembling; Disassembling of axial pumps especially adapted for elastic fluid pumps
    • 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
    • F05D2240/00—Components
    • F05D2240/50—Bearings
    • F05D2240/51—Magnetic
    • F05D2240/511—Magnetic with permanent magnets
    • 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
    • F05D2260/00—Function
    • F05D2260/30—Retaining components in desired mutual position

Definitions

  • the invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, with at least one pump stage, which comprises a stator and a rotor which rotates about an axis of rotation relative to the stator during operation, and at least one magnetic bearing for the rotor, in particular for an end region of the rotor near the inlet, which has a magnetic bearing rotor and a magnetic bearing stator cooperating therewith, each having a stack of a plurality of permanent magnet rings, the magnetic bearing rotor being attached to the rotor and the magnetic bearing stator being attached to a holder of the stator.
  • the invention also relates to a method for assembling, attaching and adjusting a magnetic bearing of such a vacuum pump.
  • turbomolecular vacuum pumps are of particular importance.
  • the pumping effect is based on an arrangement of stator blades assigned to the stator and rotor blades that are connected to the rotor.
  • the axis of rotation of the rotor runs parallel to the pumping direction, which runs from a suction side of the pump, also known as the high-vacuum side, which is provided with a pump inlet, to the outlet side of the pump, also known as the fore-vacuum side.
  • turbo pump stage This arrangement of stator blades and rotor blades is also referred to as a turbo pump stage, ie a turbo molecular vacuum pump has one or more such turbo pump stages.
  • Turbomolecular vacuum pumps typically also have one or more Holweck pump stages, which follow the at least one turbo pump stage in the pumping direction.
  • a Holweck pump stage consists of one or more cylindrical Holweck sleeves, which rotate during operation and are attached to a separate rotor or to a common rotor of turbo pump stage(s) and Holweck pump stage(s), as well as a Holweck stator.
  • the stator of a vacuum pump ie the stator blades of the turbo pump stages and the Holweck stators of the Holweck pump stages in a typical turbomolecular vacuum pump, are in practice usually separate components which are arranged in a rotationally fixed manner inside a pump housing. In principle, it is also possible to form at least some of the stators in one piece with the pump housing. In this respect, the pump housing can also be regarded as part of the stator of a vacuum pump.
  • the rotor of a turbomolecular vacuum pump is typically supported by a so-called hybrid bearing.
  • a so-called hybrid bearing On the high-vacuum side, i.e. on the inlet side, there is the already mentioned magnetic bearing between the rotor and the stator.
  • the rotor On the fore-vacuum side, that is to say on the outlet side, the rotor is mounted by means of a roller bearing, in particular a ball bearing.
  • a roller bearing in particular a ball bearing.
  • there are also purely magnetically levitated rotors which are each borne by a magnetic bearing both at their end near the inlet and at their end far from the inlet.
  • the invention is particularly advantageous for the magnetic bearing of a rotor of a turbomolecular pump stage near the inlet.
  • the invention can be used for any vacuum pumps in which there is a magnetic bearing between a rotor carrying any pump-active components and a stator having corresponding pump-active components which interact with the rotating pump-active components Has permanent magnet rings.
  • the magnetic bearing stator and the magnetic bearing rotor must be brought into an exact axial relative position in relation to the axis of rotation when assembling the vacuum pump. It must be taken into account here that the rotor has a certain axial play due to its bearing at the end remote from the inlet, ie it can be moved to a small extent in the axial direction. Therefore, when adjusting the magnetic bearing, which takes place during pump assembly, the individual permanent magnet rings are first pre-assembled on a component of the stator. This component is typically a pin which protrudes into the pump housing and is formed on a stator component which is arranged in the region of the pump inlet and has a star-shaped structure and is therefore also referred to as a stator star.
  • the pin for the magnetic bearing stator is cylindrical and arranged concentrically to the axis of rotation of the rotor. At the free end of the pin there is a set of disk springs, with the permanent magnet rings being arranged between this set of disk springs and an adjusting ring which is screwed onto the pin.
  • the permanent magnet rings can be pressed together against the restoring force of the plate spring assembly and adjusted together to adjust their axial position relative to the pin, in order to adjust the axial position of the magnetic bearing stator on the stator in this way.
  • the correct setting is achieved when the rotor, which has the mentioned small axial play, abruptly performs a small jump in the axial direction due to the interaction of the permanent magnet ring stack of stator and rotor relative to one another when setting axially.
  • the rotational position of the magnetic bearing stator on the journal at which this effect occurs is also referred to as the tilt angle.
  • This setting of the magnetic bearing is typically done in practice when the vacuum pump is lying, i.e. when the axis of rotation of the rotor is horizontal.
  • the adjustment ring is only accessible from the inlet side of the pump via elongated holes in the shape of a circular arc, with the result that the adjustment tool used to turn the adjustment ring has to be repositioned several times, since the restriction by the elongated holes means that it can only be adjusted by a comparatively small one angle can be rotated. This makes it more difficult or practically impossible to automate the adjustment process, which is still carried out manually in practice.
  • Another problem is that the spring characteristic of the plate springs is not linear. Due to thermal expansion, individual disc springs can "fold over", as a result of which the permanent ring stack is no longer sufficiently prestressed.
  • the object of the invention is therefore to simplify the assembly and adjustment of a magnetic bearing for the rotor of a vacuum pump.
  • a separate magnet carrier is provided for the magnetic bearing stator, on which the permanent magnet rings can be fully assembled independently of the holder and which can be attached to the holder together with the fully assembled permanent magnet rings as a unit, with the axial position of the magnet carrier being at the holder is adjustable.
  • the invention represents a departure from the previous practice of arranging the permanent magnet rings of the magnetic bearing stator individually directly on the stator of the vacuum pump and only then compressing them and simultaneously moving them against the restoring force of a spring in order to set the axial position required in each case. So while in the prior art explained at the outset, the compression of the permanent magnet rings and the adjustment of the axial position take place more or less simultaneously, i.e. basically no distinction can be made between the compression and the adjustment, which leads to the problems explained above, the invention is completely different Path.
  • the separate magnet carrier created by the invention enables the permanent magnet rings to be preassembled independently of the stator of the vacuum pump.
  • the permanent magnet rings can be mounted easily and in particular by machine on these separate magnet carriers, ie they can be pressed together in abutting fashion. This enables automation.
  • the unit consisting of the magnet carrier and permanent magnet rings can be manufactured and assembled in large numbers as a result.
  • the fully assembled units can each be handled completely independently of the rest of the vacuum pump and, in particular, can be manufactured externally as a purchased part will. During the final assembly of the vacuum pump, this unit can be attached to the stator as a whole. Since the permanent magnet rings are already fully assembled, the only thing left to do during assembly on the vacuum pump stator is to adjust the axial position by adjusting the axial position of the magnet carrier and thus of the permanently assembled permanent magnet stack on the stator holder.
  • Another advantage is that if the magnetic bearing or magnetic bearing stator needs to be replaced during use of the vacuum pump in the field, the individual permanent magnet rings of the magnetic bearing stator or the stator or the housing no longer have to be replaced in whole or in part, but only the unit that can be handled as a whole needs to be exchanged from magnet carrier and permanent magnet ring stack.
  • the holder has a passage running parallel to the axis of rotation, through which the magnet carrier can be inserted, starting from the inlet side of the pump, for a manual or mechanically manageable adjustment tool for adjusting the axial position of the magnet carrier is accessible.
  • the magnet carrier has an actuating section for the adjustment tool on a side facing the inlet side of the pump and aligned with the passage.
  • the adjustment tool can in particular be an Allen key that can be operated manually or by means of an automatically operating machine.
  • the actuation section of the magnet carrier then includes a corresponding hexagonal profile for this tool.
  • the magnet carrier is attached to the holder and the axial position of the magnet carrier is adjusted on the holder by screwing the magnet carrier to the holder.
  • the holder can comprise a retaining pin extending parallel to the axis of rotation, the retaining pin and the magnet carrier being arranged so as to overlap one another in the axial direction.
  • the retaining pin protrudes into the stack of permanent magnet rings mounted on the magnet carrier of the magnetic bearing stator.
  • the attachment of the magnet carrier on the retaining pin can be done in that the magnet carrier in a recess formed in the retaining pin, in particular into a passage running parallel to the axis of rotation. Alternatively, it can be attached by screwing the magnet carrier onto an outside of the holding pin.
  • the holder to which the magnet carrier can be attached is arranged in particular in the area of the pump inlet.
  • the holder can be star-shaped and can comprise an outer section, in particular an annular one, connected to a pump housing, a central section having the retaining pin and a plurality of web sections distributed in the circumferential direction, through which the central section is connected to the outer section.
  • the holder can be a one-piece, separate component that is inserted into the pump housing on the inlet side and is arranged in a rotationally fixed manner.
  • the holder can be a so-called stator star, as has already been mentioned at the outset.
  • the magnet carrier can comprise a centering sleeve, on which the permanent magnet rings are seated radially on the outside, and two abutments for the permanent magnet rings which are spaced apart from one another in the axial direction. It can be provided in particular that the centering sleeve and the holder, in particular a retaining pin of the holder, overlap one another in the axial direction.
  • the permanent magnet rings are clamped between these abutments, i.e. they are pressed together on impact.
  • one abutment in particular the abutment remote from the inlet, is formed in one piece with the centering sleeve and the other, in particular the abutment near the inlet, is a separate component which is firmly connected to the centering sleeve.
  • This separate abutment can be pressed with the centering sleeve or be screwed in order to produce the fully assembled state in this way.
  • the magnet carrier comprises a central section which is arranged concentrically to the centering sleeve and has a reduced diameter compared to the centering sleeve.
  • This central section can be designed in particular in the form of a peg.
  • the centering sleeve and the central section can be connected to one another by a connecting section located below the retaining pin of the holder.
  • the centering sleeve and the central section can be connected to one another in one piece.
  • the central section can be designed differently and fulfill different functions.
  • the central section and the centering sleeve can be arranged so that they overlap one another in the axial direction. Alternatively or additionally, the central section can protrude beyond the end of the centering sleeve that is remote from the inlet.
  • the centering sleeve can not only serve as a seat for the permanent magnet rings.
  • the magnet carrier can be screwed by means of the centering sleeve onto a retaining pin of the holder that extends parallel to the axis of rotation.
  • the centering sleeve is used to attach the magnet carrier to the holder of the stator of the vacuum pump.
  • the magnet carrier can be attached by means of a central section connected to the centering sleeve by screwing it to a holding pin of the holder, which extends parallel to the axis of rotation.
  • the central section of the magnet carrier can be screwed into a recess formed in the holding pin. This recess can in particular be a passage running parallel to the axis of rotation.
  • the central section can consequently be a threaded pin with an actuating section for an adjustment tool, which is screwed into the passage of the retaining pin and is thus accessible for the adjustment tool, starting from the inlet side.
  • one of two mutually associated bearing parts of a safety or emergency bearing for the rotor having the other bearing part can be arranged on a free end region of the magnet carrier that is remote from the inlet.
  • the provision of catch or emergency bearings for magnetically levitated rotors of vacuum pumps is known in principle.
  • the magnet carrier can be used at the same time as a component of such a catch or emergency store.
  • the corresponding bearing part for this catch or emergency bearing can be arranged in particular on a central section of the magnet carrier that is connected to a centering sleeve.
  • a clamping device which is effective in the axial direction between the magnet carrier and the holder to be provided.
  • a set axial relative position between magnet carrier and holder can be secured in this way. This is particularly advantageous when the magnet carrier and the holder are screwed together, since the clamping device eliminates the thread play. Furthermore, a sufficient self-locking of the thread can be achieved by such a clamping device. As a result, the clamping device ensures a very high degree of protection against rotation and thus secures the axial position of the magnet carrier that is set in each case.
  • the tensioning device can be a spring, for example.
  • the spring can, for example, comprise a compression spring or a wave spring.
  • the spring can be effective between a connecting section, which connects a central section and a centering sleeve of the magnet carrier to one another, and the end region, remote from the inlet, of a retaining pin of the holder that extends parallel to the axis of rotation.
  • a spring serving as a tensioning device can surround a retaining pin of the holder and be effective between a shoulder area at the transition between retaining pin and holder on the one hand and the end area of the magnet carrier near the inlet on the other.
  • the tensioning device can comprise a screw.
  • the screw can be designed as a grub screw, for example.
  • a screw serving as a tensioning device can be screwed to the holder and act on the magnet carrier in the axial direction. It can be provided, in particular, that the screw serving as a clamping device is screwed into a passage that is formed in a retaining pin of the holder that extends parallel to the axis of rotation.
  • At least one depression acting as a chip pocket can be formed in at least one of two contact surfaces of the holder and the magnet carrier that touch one another and move relative to one another when the magnet carrier is attached and adjusted.
  • the indentation can be, for example, an annular groove running around the axis of rotation.
  • One or more depressions acting as a chip pocket can be formed, for example, on the inside of the centering sleeve.
  • one or more indentations can also be formed on the outside of a retaining pin of the holder. The concept of the indentations acting as chip pockets is independent of the manner in which the magnet carrier is attached to the stator.
  • the concept of the recess(es) acting as a chip pocket(s) being provided on at least one of the contact surfaces between the centering sleeve and the retaining pin.
  • a central section of the magnet carrier can be designed as a pin with an external thread and can thus be used to screw the magnet carrier to a passage formed in a retaining pin of the holder, with the central section simultaneously having a bearing part of a catch or Notlagers may have, but this is not mandatory.
  • This also applies analogously to other components explained in connection with different developments.
  • 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 be fastened to a recipient via the inlet flange 113 and can thus be operated in a suspended manner, as it were.
  • 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 .
  • fastening bores 147 are arranged on the underside 141, via which the pump 111 can be fastened, for example, to a support surface. This is with other existing turbomolecular vacuum pumps (Not shown), which are in particular larger than the pump shown here, is not possible.
  • 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.
  • Other turbomolecular vacuum pumps (not shown) exist 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 and coaxial with the axis of rotation 151 oriented and 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 pumping-active 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 radial inner surface of the outer Holweck stator sleeve 167 lies opposite the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171 and forming with it 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 spray nut 185 is provided on the rotor shaft 153 with an outer diameter that increases towards 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 discs 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 eg 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 produces magnetic repulsive forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be supported radially.
  • the ring magnets 195 on the rotor side are carried by a support section 201 of the rotor shaft 153, which radially surrounds the ring magnets 195 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 stator-side ring magnets 197 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 structures on the rotor side prevent the structures on the stator from colliding under all circumstances will.
  • 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, the rotor shaft 153 of which extends through the motor stator 217.
  • a permanent magnet arrangement can be arranged radially on the outside or embedded on the section of the rotor shaft 153 that extends through the motor stator 217 .
  • 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 get into 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 so-called labyrinth seal 223 be provided, in particular in order to achieve better sealing of the motor compartment 217 in relation to the Holweck pump stages lying radially outside.
  • the turbomolecular vacuum pumps shown each have a pump housing 33 in which there are two pump stages, namely a turbo pump stage 11 located closer to the inlet of the pump and a Holweck pump stage 13 which is connected thereto in the pumping direction.
  • the individual stator blades 11a form the stator of the turbo pump stage 11.
  • the Holweck pump stage 13 has a stator 13a which, seen in the radial direction, is arranged between two Holweck sleeves 13b, which are attached to a common rotor 15 of the turbo pump stage 11 and the Holweck pump stage 13 in a rotationally fixed manner.
  • the stator blades 11a of the turbo pump stage 11 interact with rotor blades 11b which, like the Holweck sleeves 13b, are connected to the rotor 15 in a torque-proof manner.
  • the magnetic bearing 17 comprises a magnetic bearing rotor 19 and a magnetic bearing stator 21 (cf. Figure 6b , 7b , 8b and 9b ), each of which has a stack of permanent magnet rings 19a (magnetic bearing rotor) or 21a (magnetic bearing stator) arranged one above the other in the axial direction.
  • the axial direction here refers to the axis of rotation 14 of the rotor 15.
  • the permanent magnet rings 19a of the magnetic bearing rotor 19 are pushed together by means of an abutment 61, for example a pressed-in or screwed-in ring, and are thus attached to the rotor 15 in an axially defined position and in a rotationally fixed manner.
  • an abutment 61 for example a pressed-in or screwed-in ring
  • the magnetic bearing stator 21 is part of a structural unit which can be handled as a whole and separately from the rest of the vacuum pump and which additionally comprises a magnet carrier 25 .
  • the magnet carrier 25 is attached to a retaining pin 31, which is formed in one piece on a so-called stator star 23, which has an annular outer part 35, a central section 37 provided with the retaining pin 31, and a plurality of web sections 39 distributed in the circumferential direction that connects the central portion 37 to the outer portion 35 .
  • This stator star is a one-piece, separate component that is inserted into the pump housing 33 on the inlet side in a torque-proof manner.
  • the magnet carrier 25 is a one-piece component that can be made of metal, for example.
  • a passage 27 is formed in the cylindrical retaining pin 31 arranged concentrically to the axis of rotation 14 , which passage opens out at the free end region of the retaining pin 31 on an end face remote from the inlet.
  • the function of the retaining pin 31 and its passage 27 will be discussed in more detail below.
  • the magnet carrier 25 comprises a cylindrical centering sleeve 41 on which the permanent magnet rings 21a sit radially on the outside. At its end remote from the inlet, the centering sleeve 41 is provided with a radially outwardly projecting shoulder, which serves as an abutment 45 for the permanent magnet ring stack 21a. Furthermore, the centering sleeve 41 is connected to a peg-shaped central section 47 via an annular connecting section 49 . On its side facing the inlet, the central section 47 is provided with an actuating section 29 in the form of a Allen key (Allen key) provided. Starting from the inlet side of the pump, this actuating section 29 is accessible via the passage 27 formed in the retaining pin 31 for an adjustment tool (not shown), which is used to rotate the magnet carrier 25 about the axis of rotation 14 .
  • an adjustment tool not shown
  • the central section 37 carries a bearing part 51 of an emergency or safety bearing for the rotor 15, the other bearing part 53 being arranged on the rotor 15 (cf Figure 6b , 7b , 8b and 9b ).
  • the permanent magnet rings 21a of the magnetic bearing stator 21 are pushed together by means of an abutment 43, i.e. the stack of permanent magnet rings 21a is clamped between the two abutments 43, 45 on the magnet carrier 25 and is thus fully assembled on the magnet carrier 25.
  • the abutment 43 is designed as a clamping ring, which is pressed or screwed onto the centering sleeve 41 of the magnet carrier 25 during assembly of the magnet bearing stator 21 on the magnet carrier 25 - depending on the specific configuration.
  • the unit consisting of the magnet carrier 25 and the magnet bearing stator 21 fully assembled on this is a separate subassembly that can be handled as a whole and manufactured and assembled independently of the rest of the vacuum pump.
  • the exemplary embodiments described here differ in particular with regard to the way in which the magnet carrier 25 is attached to the retaining pin 31 of the stator star 23 and with regard to the way in which a clamping device is used between the stator star 23 and the magnet carrier 25.
  • the magnet carrier 25 together with the fully assembled magnetic bearing stator 21 is screwed onto the retaining pin 31 with the centering sleeve 41 .
  • a screw thread 63 is used for this purpose, ie in this area the Inside of the centering sleeve 41 with an internal thread and the outside of the retaining pin 31 with an external thread.
  • the screwing takes place by turning the magnet carrier 25 by means of the adjustment tool already mentioned, which interacts with the actuating section 29 formed on the central section 47 .
  • a recess 59 designed as a circumferential groove is provided on the outside of the retaining pin 31 and serves as a pocket for chips.
  • the tensioning device mentioned here comprises a compression spring 57 which is arranged between the end face remote from the inlet at the free end of the holding pin 31 and the side of the central section 47 pointing towards the inlet.
  • the compression spring 57 eliminates the play in the thread 63 and at the same time ensures that this thread 63 is sufficiently self-locking. As a result, the magnet carrier 25 is reliably secured against unintentional twisting.
  • FIG. 7a and 7b differs from the exemplary embodiment described above in that a grub screw 57 is provided as the clamping device, which is screwed into the passage 27 in the retaining pin 31 provided with a corresponding internal thread.
  • this clamping screw 57 acts on the central section 47 on a counter surface 57b surrounding the actuating section 29 with a corresponding cone angle.
  • the grub screw 57 can be turned by means of a tool (not shown), for example an Allen key, which interacts with a corresponding profile (not shown) formed on the side of the tightening screw 57 pointing towards the inlet.
  • Figure 8a and 8b combines the two variants according to the clamping device Figure 6a and 6b on the one hand and Figure 7a and 7b on the other hand.
  • the bracing and thus the anti-twist device is carried out here both by a compression spring 57 according to FIG Figure 6a and 6b as well as by a grub screw 57 according to Figure 7a and 7b .
  • a particularly high degree of security against rotation for the magnet carrier 25 is achieved.
  • the clamping by means of the grub screw 57 only takes place when the required axial position of the magnet carrier 25 has been reached by turning.
  • a wave spring 57 is provided as a tensioning device.
  • the wave spring 57 is arranged at the base of the retaining pin 31 , ie the wave spring 57 surrounds the retaining pin 31 and is supported with its side pointing towards the inlet on a shoulder area at the transition between the retaining pin 31 and the central section 37 of the stator spider 23 . With its other end, the wave spring 57 acts on the assembly consisting of the magnet carrier 25 and the magnetic bearing stator 21.
  • the magnet carrier 25 is not attached to the retaining pin 31 by screwing it using the centering sleeve 41 of the magnet carrier 25.
  • the central section 47 of the magnet carrier 25 extends from the connecting section 49 to the inlet side of the pump, i.e. into the centering sleeve 51 and thus in the direction of the Holding pin 31.
  • the length of this pin-shaped part of the central section 47 is dimensioned such that the central section 47 can be screwed into the passage 27 of the holding pin 31.
  • a screw thread 63 is provided for this purpose, which comprises an external thread on the central section 47 and an internal thread of the retaining pin 31 formed in the passage 27 .
  • the screwing of the magnet carrier 25 to the holding pin 31 is in turn effected by actuating the central section 47 on the operating section 29 which is formed on the pin-shaped section of the central section 47 which is screwed into the holding pin 31 .
  • a clamping device which is arranged here as a compression spring 57 between the front end of the retaining pin 31 and the connecting section 49 of the magnet carrier 25, serves to eliminate play and self-locking of the thread 73 and thus to prevent the magnet carrier 25 from rotating.
  • One or more indentations can be provided on at least one of the contact surfaces between holding section 31 and centering sleeve 41, which, as in the other exemplary embodiments, serve as chip pockets.
  • a bore 67 is formed in the connecting section 49, through which it is avoided that a so-called dead volume is present within the centering sleeve 41 when the magnet carrier 25 is mounted.
  • the bore 67 allows this space to be evacuated during operation of the vacuum pump.
  • One or more corresponding evacuation openings, such as bore 67, can also be provided in the other exemplary embodiments.
  • the fit between the permanent magnet rings 21a and the outside of the centering sleeve 41 is a loose fit in all of the exemplary embodiments. This also applies to the fit between the outside of the retaining pin 31 and the inside of the centering sleeve 41 in the embodiment of FIG 10 , in which the screw connection does not take place between the retaining pin 31 and the centering sleeve 41.
  • the magnetic bearing stator 21 can first be preassembled on the magnet carrier 25 independently of the assembly of a respective vacuum pump.
  • the permanent magnet rings 21a can therefore be completely independent of the rest of the vacuum pump and in particular arranged independently of the retaining pin 31 of the stator star 23 on the centering sleeve 41 and finally by means of the abutment 43, for example a press-on or screw-on ring, pressed against the other abutment 45 and thus compressed with impact and thus fully assembled.
  • This prefabricated assembly is then screwed to the retaining pin 31 in the manner described above, with the compression or wave spring 57 serving as a tensioning device being interposed if necessary.
  • the correct relative axial position of the magnetic bearing stator 21 can be set immediately afterwards or at a later point in time by adjusting the axial position of the magnet carrier 25 by turning it, as has been described in the introductory part.
  • a grub screw which also serves as a tensioning device, is used as a tensioning device (cf. Figure 7a , 7b and Figure 8a , 8b ), then, after setting the correct axial position, the grub screw 57 is tightened in order to eliminate the thread play between the retaining pin 31 and the centering sleeve 41 and to ensure the self-locking of this screw thread, which ensures a high degree of security against torsion.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
EP22193059.7A 2022-08-31 2022-08-31 Pompe à vide dotée d'un support d'aimants réglable dans une direction axiale Pending EP4108930A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP22193059.7A EP4108930A1 (fr) 2022-08-31 2022-08-31 Pompe à vide dotée d'un support d'aimants réglable dans une direction axiale
JP2023048032A JP2024035041A (ja) 2022-08-31 2023-03-24 真空ポンプ

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22193059.7A EP4108930A1 (fr) 2022-08-31 2022-08-31 Pompe à vide dotée d'un support d'aimants réglable dans une direction axiale

Publications (1)

Publication Number Publication Date
EP4108930A1 true EP4108930A1 (fr) 2022-12-28

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP22193059.7A Pending EP4108930A1 (fr) 2022-08-31 2022-08-31 Pompe à vide dotée d'un support d'aimants réglable dans une direction axiale

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EP (1) EP4108930A1 (fr)
JP (1) JP2024035041A (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030155830A1 (en) * 2000-05-06 2003-08-21 Christian Beyer Magnetic bearing with damping
EP2933496A2 (fr) * 2014-04-17 2015-10-21 Pfeiffer Vacuum GmbH Pompe à vide
EP3018373A1 (fr) * 2014-11-07 2016-05-11 Pfeiffer Vacuum GmbH Pompe à vide
EP3106668A1 (fr) * 2015-06-17 2016-12-21 Pfeiffer Vacuum Gmbh Pompe à vide
US20190368499A1 (en) * 2016-11-25 2019-12-05 Edwards Limited Pump bearing holders
EP3683447A1 (fr) * 2019-12-19 2020-07-22 Pfeiffer Vacuum GmbH Pompe à vide

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030155830A1 (en) * 2000-05-06 2003-08-21 Christian Beyer Magnetic bearing with damping
EP2933496A2 (fr) * 2014-04-17 2015-10-21 Pfeiffer Vacuum GmbH Pompe à vide
EP3018373A1 (fr) * 2014-11-07 2016-05-11 Pfeiffer Vacuum GmbH Pompe à vide
EP3106668A1 (fr) * 2015-06-17 2016-12-21 Pfeiffer Vacuum Gmbh Pompe à vide
US20190368499A1 (en) * 2016-11-25 2019-12-05 Edwards Limited Pump bearing holders
EP3683447A1 (fr) * 2019-12-19 2020-07-22 Pfeiffer Vacuum GmbH Pompe à vide

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