EP4549740A2 - Pompe à vide optimisée en termes de technique d'écoulement et de température - Google Patents

Pompe à vide optimisée en termes de technique d'écoulement et de température Download PDF

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Publication number
EP4549740A2
EP4549740A2 EP25164817.6A EP25164817A EP4549740A2 EP 4549740 A2 EP4549740 A2 EP 4549740A2 EP 25164817 A EP25164817 A EP 25164817A EP 4549740 A2 EP4549740 A2 EP 4549740A2
Authority
EP
European Patent Office
Prior art keywords
holweck
rotor
vacuum pump
sleeve
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
EP25164817.6A
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German (de)
English (en)
Other versions
EP4549740A3 (fr
Inventor
Jan Hofmann
Maximilian Birkenfeld
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 EP25164817.6A priority Critical patent/EP4549740A3/fr
Publication of EP4549740A2 publication Critical patent/EP4549740A2/fr
Publication of EP4549740A3 publication Critical patent/EP4549740A3/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
    • 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
    • F04D19/044—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
    • 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
    • F04D19/046—Combinations of two or more different types of pumps

Definitions

  • the present invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, with at least one Holweck pumping stage, wherein the vacuum pump and in particular its Holweck pumping stage is optimized in terms of fluid dynamics and/or thermal aspects.
  • Vacuum pumps are used in many areas of industry and research. The basic design of such vacuum pumps is well known, which is why we will refer to the EP 4 108 931 A1 is referred to.
  • turbomolecular vacuum pumps with an integrated Holweck pumping stage are technically sophisticated devices that fulfill their purpose, there is nevertheless a continuing need to optimize such turbomolecular vacuum pumps in terms of fluid dynamics and/or thermal aspects.
  • the invention is therefore based on the object of providing a vacuum pump and in particular a turbomolecular vacuum pump which meets the previously described need.
  • this object is achieved with a vacuum pump, in particular with a turbomolecular vacuum pump, which is characterized by the features of claim 1 and in particular in that the diameter of the radially outer Holweck rotor sleeve or the second diameter is at least 30% and preferably at least 35% larger than the diameter of the radially inner Holweck rotor sleeve or the first diameter.
  • the radially outer Holweck rotor sleeve thus has a significantly larger diameter than the radially inner Holweck rotor sleeve.
  • the core wall thickness which in the context of this application is also referred to simply as the wall thickness for the sake of simplicity, refers here to the pure wall thickness of the stator sleeve between the inner surface and the outer surface, where the internal and external threads are formed.
  • the invention proposes for the first time to make the diameter of the radially outer Holweck rotor sleeve significantly larger than the diameter of the radially inner Holweck rotor sleeve in order to create more space between the two Holweck rotor sleeves for a correspondingly thicker Holweck stator sleeve, which then has a lower thermal resistance due to its greater wall thickness, which allows the heat to be better conducted from the free end of the Holweck stator sleeve towards the fixed end of the Holweck stator sleeve or to the stationary housing section.
  • the Holweck stator sleeve due to the significantly larger diameter of the outer Holweck rotor sleeve compared to the diameter of the inner Holweck rotor sleeve, it is possible according to the invention to form the Holweck stator sleeve with a core wall thickness that is greater than 5 mm, preferably greater than 6 mm, and particularly preferably greater than 7 mm, essentially over its entire axial extent between its fixed end and its free end.
  • the Holweck stator sleeve has a certain core wall thickness "essentially" over its entire axial extent, this means that an axial region of the Holweck stator sleeve located near the free end can be excluded from this, which is defined by the last two turns, preferably by the last turn of the internal or external thread, as will be explained in more detail below.
  • At least two concentric and axially extending annular webs are formed at the free end of the Holweck stator sleeve, and at least two concentric and axially extending annular webs are also formed on the hub of the Holweck rotor, which are nested with the annular webs located at the free end of the Holweck stator sleeve. Any accumulated heat that builds up in the rotor hub can thus be transferred via the nested annular webs to the Holweck stator sleeve, which, due to its reduced thermal resistance, can then dissipate this heat into the housing base or the stationary housing section.
  • the Holweck stator sleeve is penetrated in the radial direction near its free end by a plurality of gas flow bores which are evenly spaced from one another in the circumferential direction, so that the process gas to be pumped can flow through these between the radially outer and the radially inner Holweck gap.
  • the underlying object is further achieved with a vacuum pump, in particular with a turbomolecular vacuum pump, which is characterized by the features of claim 6 and in particular in that the radially inner Holweck rotor sleeve has an axial extent which is 30% to 70%, preferably 40% to 60%, in particular 45% to 55%, of the axial extent of the outer Holweck rotor sleeve.
  • the Holweck stator sleeve has a base ring section attached to the stationary housing section and a cantilever ring section which extends from an end face of the base ring section facing the rotor hub in the axial direction to the free end of the Holweck stator sleeve in the annular space between the inner Holweck rotor sleeve and the outer Holweck rotor sleeve.
  • the cantilever ring section and the base ring section preferably have the same outer diameter, which allows the external thread of the Holweck stator sleeve to be formed on both the outer surface of the base ring section and the cantilever ring section.
  • the cantilever ring section can have a cylindrical inner surface with an internal thread formed thereon, in which case it can preferably be provided that the number of threads of the internal thread corresponds to the number of threads of the external thread.
  • the design of the Holweck stator sleeve with the relatively massive base ring section proves to be advantageous, since in this case the base ring section can support the motor stator of the electric motor driving the rotor shaft.
  • the base ring section forms an annular inner surface that supports the motor stator.
  • a further embodiment can provide for the base ring section to be penetrated in the axial direction by a plurality of gas flow bores, preferably evenly spaced from one another in the circumferential direction. From a fluidic point of view, it can prove advantageous for the gas flow bores in question to also extend in the circumferential direction and/or in the radial direction. Likewise, from a fluidic point of view, it can also prove advantageous for the gas flow bores to each have an elongated hole cross-section when viewed in the axial direction, in order to reduce flow resistance.
  • gas flow holes in the same number as the threads of the internal thread of the cantilever section, so that the process gas flowing out of a respective thread can flow directly into a gas flow hole assigned to it.
  • the annular grooves in question can also be formed in the axial continuation of the radially inner Holweck rotor sleeve in the end face of the stationary housing section.
  • the annular grooves in question are thus located where the process gas is deflected around the free end of the respective Holweck rotor sleeve and thus in an area in which friction-related temperature peaks can arise due to the gas deflection.
  • the annular grooves in question serve, to a certain extent, as cooling fins through which the process gas is cooled, thereby preventing undesirable temperature peaks.
  • the object underlying the same is further achieved with a vacuum pump, in particular with a turbomolecular vacuum pump, which is characterized by the features of claim 13.
  • a vacuum pump in particular with a turbomolecular vacuum pump, which is characterized by the features of claim 13.
  • the internal and external threads or the end faces in question have a defined offset to each other in the circumferential direction, thus, the gas flowing out of the external thread at the free end of the Holweck stator sleeve can flow into the corresponding threads of the internal thread without major flow losses, without friction-related flow losses occurring at the end face or at the free end of the Holweck stator sleeve, which would otherwise reduce the pump's suction capacity and result in increased power consumption of the pump.
  • the number of first thread lands can be equal to the number of second thread lands, so that each thread groove of the external thread is assigned, so to speak, exactly one corresponding thread groove of the internal thread.
  • a gas flowing out of a thread groove of the external thread can thus flow directly into a corresponding thread groove of the internal thread without causing undesirable gas turbulence when flowing around the free end of the Holweck stator sleeve.
  • a further embodiment can provide several evenly spaced flow contours in the circumferential direction at the free end of the Holweck stator sleeve, in the same number as the first and second thread lands. Each of these flow contours defines a defined thread flow path between a thread groove of the internal thread and a thread groove of the external thread, so that no undesirable gas turbulence occurs at the free end of the Holweck stator sleeve.
  • the flow contours in question may, for example, be guide vanes that extend between the end faces of the first thread lands and the end faces of the second thread lands.
  • Guide vanes thus represent, in a sense, a continuation of the threaded webs at the free end or at the end face of the Holweck stator sleeve.
  • first and second end faces In addition to or as an alternative to the circumferential offset d of the first and second end faces relative to one another, it can further be provided that the first end faces and/or the second end faces enclose an acute angle with a plane in which the free end of the Holweck stator sleeve lies, which angle is in particular between 10° and 40°, preferably between 20° and 30°.
  • the process gas After flowing around the free end of the Holweck stator sleeve, the process gas therefore does not directly impact the first end face of the thread lands of the internal thread when flowing into the internal thread of the Holweck stator sleeve; rather, the process gas is slightly deflected by the slightly inclined first end faces before subsequently flowing into the thread grooves of the internal thread.
  • Corresponding considerations apply to the case of a vacuum pump with a Holweck pumping stage, in which the process gas first flows through the internal thread and then the external thread of the Holweck stator sleeve.
  • the Holweck stator sleeve in addition to or as an alternative to the design with end faces offset from one another in the circumferential direction and the acute-angled alignment of the end faces, it may be appropriate to design the Holweck stator sleeve such that it has a core wall thickness that decreases towards the free end of the Holweck stator.
  • the Holweck stator sleeve has a substantially constant core wall thickness over its axial extent; the decrease in the core wall thickness, however, is limited only to a region defined by the first two turns of the internal thread and/or the external thread closest to the free end of the Holweck stator sleeve, preferably only by the first turn of the internal thread and/or the external thread.
  • the core wall thickness therefore decreases towards the free end of the Holweck stator sleeve only in a very limited area, which is defined by a type of internal and/or external chamfer of the Holweck stator sleeve is formed at its free end, whereby this chamfer can have a linear, convex, round or parabolic contour.
  • the thread depth of the internal and/or external thread increases towards the free end of the Holweck stator sleeve and, at the same time, the thickness reduction at the free end of the stator sleeve creates an optimized flow geometry that enables flow around the free end of the Holweck stator sleeve with fewer losses.
  • the object underlying the same is further achieved with a vacuum pump, in particular with a turbomolecular pump stage, which is characterized by the features of claim 20 and in particular in that a flow profile with a concave cross section is provided on the rotor hub of the Holweck rotor between the two Holweck rotor sleeves, which flow profile concentrically surrounds the rotor shaft.
  • the flow profile in question can be a separate part attached to the hub. This flow profile also ensures turbulence-free flow around the free end of the Holweck stator sleeve, which in turn has a positive effect on the pump's suction capacity and power consumption.
  • the following section discusses further design options for the vacuum pump according to the four aspects explained above.
  • the design options explained below which are also referred to as variations, relate in particular to a special design of the Holweck pump stage. the vacuum pump of the four aspects explained above and in particular on the design of the rotor hub of the Holweck pumping stage.
  • Variation 2 concerns the vacuum pump according to Variation 1, wherein the rotor hub carries at least two mutually concentric Holweck rotor sleeves, wherein the at least two mutually concentric annular webs are provided radially inside the at least two Holweck rotor sleeves.
  • Variation 3 concerns the vacuum pump according to Variation 1 or 2, wherein the at least one balancing area is located on the outer circumference of the rotor hub between two adjacent pump blades.
  • Variation 4 relates to the vacuum pump according to one of the variations 1 to 3, wherein the pump blades provided along the outer circumference of the rotor hub are spaced apart from one another in the circumferential direction without overlapping, wherein the at least one balancing region is located in the non-overlapping region between two adjacent pump blades.
  • Variation 5 relates to the vacuum pump according to any one of variations 2 to 4, wherein the at least one balancing region is located between the at least two Holweck rotor sleeves.
  • Variation 6 relates to the vacuum pump according to any one of variations 1 to 5, wherein the rotor hub forms an annular retaining web for each Holweck rotor sleeve, each of which carries a Holweck rotor sleeve, wherein at least one radially outermost retaining web has a radially outer exposed annular surface.
  • Variation 7 concerns the vacuum pump according to Variation 6, wherein the at least one balancing region is located on the radially outer exposed annular surface of the radially outermost retaining web.
  • Variation 8 relates to the vacuum pump according to one of variations 1 to 7, wherein the rotor hub forms at least one balancing ring concentric with the at least one Holweck rotor sleeve, on which the at least one balancing region is located.
  • Variation 9 concerns the vacuum pump according to Variation 8, wherein the balancing ring is located in the radial direction between two Holweck rotor sleeves, in particular on the side of the rotor hub opposite the Holweck rotor sleeves.
  • Variation 10 relates to the vacuum pump according to any one of variations 1 to 9, wherein the vacuum pump further comprises at least one surface-treated portion on the rotor hub and at least one sensor device with which a temperature of the at least one surface-treated portion of the Rotor hub can be determined without contact by measuring the heat radiation emitted by the section.
  • Variation 11 concerns the vacuum pump according to Variation 10, wherein the sensor device comprises an infrared sensor.
  • Variation 12 concerns the vacuum pump according to Variation 10 or 11, wherein the section of the rotor hub is roughened or structured, in particular wherein the section of the rotor hub is roughened or structured such that it has an average roughness Ra of 5 to 25 ⁇ m and/or an average roughness depth Rz of 40 to 100 ⁇ m and/or that the section has surface structures in the range 15 to 50 ⁇ m.
  • Variation 13 relates to the vacuum pump according to any one of variations 10 to 12, wherein the surface-treated portion consists essentially of a material of the rotor hub in the region of the portion.
  • Variation 14 relates to the vacuum pump according to any one of variations 10 to 13, wherein the portion has a coating.
  • 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 housed in the electronics housing 123, e.g., for operating an electric motor 125 arranged in the vacuum pump (see also Fig. 3 ).
  • Several connectors 127 for accessories are provided on the electronics housing 123.
  • a data interface 129 e.g., according to the RS485 standard, and a power supply connector 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 flooding inlet 133 On the housing 119 of the turbomolecular pump 111, a flooding inlet 133, in particular in the form of a flooding valve, is provided, via which the vacuum pump 111 can be flooded.
  • a Sealing gas connection 135, which is also referred to as purge gas connection is arranged, via which purge gas is supplied to protect the electric motor 125 (see e.g. Fig. 3 ) can be admitted into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111, before the gas delivered by the pump.
  • coolant connections 139 are arranged in the lower part 121, one of which serves as an inlet and the other as an outlet for coolant, which can be fed into the vacuum pump for cooling purposes.
  • Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.
  • the lower side 141 of the vacuum pump can serve as a base, so that the vacuum pump 111 can be operated standing on the underside 141.
  • the vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and thus operated in a suspended position.
  • the vacuum pump 111 can be designed so that it can also be operated when oriented in a different way than in Fig. 1 As shown.
  • Embodiments of the vacuum pump can also be realized in which the underside 141 is arranged facing sideways or upwards rather than downwards. In principle, any angle is possible.
  • Mounting holes 147 are also arranged on the underside 141, via which the pump 111 can be attached, for example, to a support surface. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here.
  • a coolant line 148 is shown in which the coolant introduced and discharged via the coolant connections 139 can circulate.
  • the vacuum pump comprises several process gas pumping 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 rotatable about a rotation axis 151.
  • the turbomolecular pump 111 comprises several turbomolecular pumping stages connected in series for pumping purposes, with several radial rotor disks 155 attached to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and secured in the housing 119.
  • a rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular pumping stage.
  • the stator disks 157 are held at a desired axial distance from one another by spacer rings 159.
  • the vacuum pump also includes Holweck pump stages arranged radially one inside the other and connected in series for pumping efficiency.
  • Other turbomolecular vacuum pumps exist that do not have Holweck pump stages.
  • the rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical-shell-shaped Holweck rotor sleeves 163, 165 attached to and supported by the rotor hub 161, which are oriented coaxially to the rotation axis 151 and nested within one another in the radial direction. Furthermore, two cylindrical-shell-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the rotation axis 151 and nested within one another in the radial direction.
  • the pumping surfaces of the Holweck pump stages are formed by the lateral surfaces, i.e., 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 together with the latter forms the first Holweck pump stage following the turbomolecular pumps.
  • the radial inner surface of the outer Holweck rotor sleeve 163 lies opposite the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together with the latter forms a second Holweck pump stage.
  • the radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175 and together forming the third Holweck pumping stage.
  • a radially extending channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173.
  • a radially extending channel can be provided, via which the central Holweck gap 173 is connected to the radially inner Holweck gap 175.
  • the nested Holweck pump stages are connected in series with one another.
  • a connecting channel 179 to the outlet 117 can also be provided in the internal Holweck rotor sleeve 165.
  • the above-mentioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves extending spirally around the rotation axis 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and propel the gas in the Holweck grooves for operating the vacuum pump 111.
  • a rolling bearing 181 is provided in the area of the pump outlet 117 and a permanent magnet bearing 183 is provided in the area of the pump inlet 115.
  • a conical spray nut 185 with an outer diameter increasing toward the rolling bearing 181 is provided on the rotor shaft 153.
  • the spray nut 185 is in sliding contact with at least one wiper of a fluid reservoir.
  • a spray screw can be provided instead of a spray nut. Since different designs are thus possible, the term "spray tip" is also used in this context.
  • the operating fluid reservoir comprises several stacked absorbent discs 187 which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.
  • the operating fluid is transferred by capillary action from the operating fluid reservoir via the wiper to the rotating injection nut 185 and, as a result of the centrifugal force, is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 to the rolling bearing 181, where it fulfills a lubricating function, for example.
  • the rolling bearing 181 and the operating fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.
  • the permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each comprising a ring stack of several permanent magnetic rings 195, 197 stacked one on top of the other in the axial direction.
  • the ring magnets 195, 197 lie opposite one another, forming a radial bearing gap 199, with the rotor-side ring magnets 195 being arranged radially on the outside and the stator-side ring magnets 197 being arranged radially on the inside.
  • the magnetic field present in the bearing gap 199 creates magnetic repulsion forces between the ring magnets 195, 197, which effect a radial bearing of the rotor shaft 153.
  • the rotor-side ring magnets 195 are carried by a support section 201 of the rotor shaft 153, which surrounds the ring magnets 195 on the radial outside.
  • the stator-side ring magnets 197 are supported by a stator-side support section 203, which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119.
  • the rotor-side ring magnets 195 are secured parallel to the rotation axis 151 by a cover element 207 coupled to the support section 201.
  • the stator-side ring magnets 197 are secured parallel to the rotation axis 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 magnets 197.
  • an emergency or safety bearing 215 which runs idle without contact during normal operation of the vacuum pump 111 and only engages upon excessive radial deflection of the rotor 149 relative to the stator, forming a radial stop for the rotor 149 to prevent a collision of the rotor-side structures with the stator-side structures.
  • the safety 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 disengage during normal pumping operation.
  • the radial deflection at which the backup bearing 215 engages is 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 a collision of the rotor-side structures with the stator-side structures is prevented under all circumstances.
  • the vacuum pump 111 comprises 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.
  • a permanent magnet arrangement can be arranged radially on the outside or embedded in the portion of the rotor shaft 153 extending through the motor stator 217.
  • an intermediate space 219 is arranged, which comprises a radial motor gap, via which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.
  • the motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125.
  • a seal gas also referred to as purge gas, which can be, for example, air or nitrogen, can enter the motor compartment 137 via the seal gas connection 135.
  • the seal gas can be used to protect the electric motor 125 from process gas, e.g., from corrosive components of the process gas.
  • the motor compartment 137 can also be evacuated via the pump outlet 117, i.e., the vacuum pressure in the motor compartment 137 is at least approximately the vacuum pressure generated by the backing pump connected to the pump outlet 117.
  • a so-called labyrinth seal 223, which is known per se, can be provided between the rotor hub 161 and a wall 221 delimiting the motor compartment 137, in particular in order to achieve a better sealing of the motor compartment 217 with respect to the Holweck pump stages located radially outside.
  • the Fig. 6 shows an enlarged section of the Fig. 4 in particular to explain the first aspect of the present invention, according to which the outer rotor sleeve 163 has a significantly larger diameter than the inner rotor sleeve 165, which according to the invention makes it possible to provide a significantly thicker Holweck stator sleeve 169 between the two rotor sleeves 163, 165.
  • the radially outer Holweck rotor sleeve 163 has a diameter that is at least 30%, preferably at least 35%, larger than the diameter of the radially inner Holweck rotor sleeve 165.
  • the stator sleeve is usually a relatively delicate component whose core wall thickness is not much greater than the wall thickness of the rotor sleeves; see, for example, the Fig. 3 and 4 .
  • the diameter of the radially outer rotor sleeve 163 is now selected to be significantly larger than the diameter of the radially inner rotor sleeve 165, a stator sleeve 169 with a significantly greater core wall thickness can now be used between the two rotor sleeves 163, 165, which is greater than 5 mm, preferably greater than 6 mm and particularly preferably greater than 7 mm.
  • the core wall thickness which for the sake of simplicity is also referred to here as the wall thickness, is measured from the groove base 302 of the external thread 304 to the groove base 302 of the internal thread 308 and thus represents the thickness of the stator sleeve 169 less the height of the thread lands 306, 310 of the external thread 304 and the internal thread 308. Due to the significantly thicker design of the stator sleeve 169, it has a lower thermal resistance, so that hardly any heat builds up at the free end 322 of the stator sleeve 169, since this can be continuously dissipated in the direction of the housing base or the stationary housing section 121.
  • a plurality of mutually concentric annular webs 324 are formed, which are nested with corresponding annular webs 326 extending axially from the rotor hub 161.
  • the nested annular webs 324, 326 act, in a sense, as a type of heat exchanger, via which heat can be dissipated from the rotor hub 161 to the stator sleeve 169 and from there to the stationary housing section 121 in the manner explained above.
  • stator sleeve 169 is penetrated in the radial direction near its free end 322 by a plurality of gas flow bores 328 through which the process gas can flow in the desired manner from the outer Holweck gap or from the external thread 304 into the inner Holweck gap or into the internal thread 308.
  • a plurality of mutually concentric annular grooves 330 are formed in the housing lower part 121. These are located in the embodiment of the Fig. 6 in the lower part 121 radially outside the Holweck stator sleeve 169, whereby additionally or alternatively it can be provided that corresponding annular grooves are also located radially inside the Holweck stator sleeve 169 in the lower part 121 and thus in continuation of the inner rotor sleeve 165.
  • annular grooves 330 in the lower part 121 act as cooling fins, which cool the process gas flowing over them in the desired manner, so that friction-related heating of the stator sleeve 169 in the region of the free end 322 thereof cannot even occur.
  • corresponding annular grooves 330 can be provided in the lower housing part 121 of the pump 111.
  • the inner Holweck rotor sleeve 165 has a significantly shorter axial extension than the radially outer Holweck rotor sleeve 163.
  • the axial extension of the inner Holweck rotor sleeve 165 is only about 45% to 55% of the axial extension the radially outer Holweck rotor sleeve 163.
  • the stator sleeve 169 is composed of a base ring portion 332, which is attached to the housing lower part 121, and a collar ring portion 434 extending axially from the base ring portion 332.
  • the collar ring portion 334 extends from the end face of the base ring portion 332 facing the rotor hub 161 and thus extends into the annular space between the shorter inner rotor sleeve 165 and the longer outer rotor sleeve 163.
  • the external thread 304 of the stator sleeve 169 extends axially over the entire common outer surface 354 of the base ring portion 332 and the collar portion 334, whereas the internal thread 308 is provided only over the axial extent of the collar portion 334 on its inner side.
  • the motor stator 217 of the electric motor 125 driving the rotor shaft 153 can be attached directly to the annular inner surface 336 of the base ring section 332.
  • the base ring section 332 is penetrated in the axial direction by a plurality of gas flow bores 338, which are preferably present in the same number as the threads of the internal thread. As shown, these can be aligned obliquely to the rotation axis 151 and thus also extend partially in the radial direction. the gas flow holes 338 may also extend at least partially in the circumferential direction, even if this is not shown in the illustration of the Fig. 7 is not recognizable.
  • the previously described temperature problem which results in undesirably strong heating of the stator sleeve 169 in the area of its free end 322, is due, among other things, to the undesirable swirling of the process gas as it flows from the external thread 304 over the free end 322 into the internal thread 308.
  • This is particularly the case because, in conventional Holweck pump stages, there is no specific assignment of the thread grooves of the external thread 304 to the thread grooves of the internal thread 308. In other words, this means that a gas flowing out of a thread groove of the external thread 304 is distributed between two or more thread grooves of the internal thread 304.
  • the invention proposes for the first time to align the external thread 304 and the internal thread 308 rotationally relative to one another in the circumferential direction in such a way that process gas flowing out of a thread groove of the external thread 304, after flowing around the free end 322, flows as far as possible only into a single thread groove of the internal thread 308.
  • the end faces 304 which form the thread webs 306 of the external thread 304 at the free end 322 of the Holweck stator sleeve 169, have an offset d in the circumferential direction compared to the end faces 344, which form the thread webs 310 of the internal thread 308 at the free end 322 of the stator sleeve 169, see the Fig. 8 .
  • process gas flowing out of a thread groove of the external thread 304 flows diagonally over the free end 322 of the stator sleeve 169 in a targeted manner, in order to then flow into exactly one thread groove of the internal thread 308 on the inside of the stator sleeve 169, which of course requires that the number of thread lands 306 of the external thread 304 is the same as the number of thread lands 310 of the internal thread 308.
  • the end faces 344 of the threaded webs 310 of the internal thread 308 enclose an acute angle ⁇ with the plane in which the free end 322 of the Holweck stator sleeve 169 lies, which angle is preferably between 10 and 40°, in particular preferably between 20 and 30°.
  • the core wall thickness decreases towards the free end 322 of the Holweck stator sleeve 169, since this corresponds to an increase in the height of the threaded webs 306, 310 at the free end 322 of the stator sleeve 169.
  • the inflow cross-section into the threaded grooves of the internal thread 308 is increased, which facilitates the flow of the process gas into the threaded grooves of the internal thread 308.
  • the wall thickness can taper towards the free end 322 in the sense of a chamfer 346, which is preferably formed only on the inside of the free end 322 of the stator sleeve 169.
  • the chamfer 346 has a straight or linear contour; however, as shown, the chamfer 346 can also be provided on the outside and have a convex, round or parabolic contour, as shown in dashed lines.
  • the chamfer 346 extends only over the first turn of the internal thread 308; however, as shown in dash-dotted lines, the chamfer 346 can also extend over an area defined by the two turns of the internal thread 308 closest to the free end 322.
  • a flow profile 356 with a concave cross-section is provided on the rotor hub 161 of the Holweck rotor between the two Holweck rotor sleeves 163, 165, which concentrically surrounds the rotor shaft 153.
  • the flow profile 356 is a part that can be handled separately from the hub 161 and is attached to the hub 161. This flow profile 356 also ensures a turbulence-free flow around the free end 322 of the Holweck stator sleeve 169, which in turn has a positive effect on the pump's suction capacity and its power consumption.
  • the Holweck stator sleeve 169 has at its free end 322 a plurality of flow contours 348 evenly spaced from one another in the circumferential direction, each flow contour 348 defining a defined flow path between a thread groove of the external thread 304 and a single thread groove of the internal thread 308, as is illustrated by the flow arrow S.
  • the flow contours 348 can be guide vanes 350 formed on the free end 322 of the stator sleeve 169, each extending between an end face 340 of the external thread 304 and an end face 344 of the internal thread 308. Contrary to the embodiment shown, these can be curved, in particular concave or convex, in order to guide the process gas over the free end 322 of the stator sleeve 169 with as little turbulence as possible.
  • the Fig. 11 shows an enlarged section of the Fig. 4 to explain the pump blades 230 provided on the outer circumference of the rotor hub 161.
  • the rotor shaft 153 of the rotor can be seen, which supports the rotor hub 161, to which the two concentric Holweck rotor sleeves 163, 165 are fastened, which can preferably be made of a CFRP material.
  • the Holweck stator sleeves 167, 169 are not shown here for the sake of clarity.
  • the rotor hub 161 has a plurality of pump blades 230 along its outer circumference, which are spaced apart from one another evenly in the circumferential direction. are spaced apart. Between these pump blades 230, material can be removed from the outer circumference of the rotor hub 161 in a balancing area 234 by means of laser ablation in order to compensate for any imbalances in the rotor.
  • the pump blades 230 can be spaced apart from one another in the circumferential direction without overlap. This offers the possibility of locating the balancing area 234 in the non-overlapping area between two adjacent pump blades and thus performing the material removal precisely where the pump blades 230 do not overlap in the circumferential direction.
  • the balancing area 234 can also be located between the two Holweck rotor sleeves 163, 165.
  • the rotor hub 161 carries the two concentric Holweck rotor sleeves 163, 165. Specifically, the rotor hub 161 forms two annular retaining webs 236, 238, each of which carries a Holweck rotor sleeve 163, 165. As the Fig. 11 can be easily removed, the radially outermost retaining web 236 has a radially outer exposed annular surface 242 on which the rotor or the rotor hub 161 can be balanced, as can be seen from the balancing area 234 shown.
  • the rotor hub 161 forms, on the side of the rotor hub 161 opposite the Holweck rotor sleeves 163, 165, a balancing ring 240 which is concentric with the Holweck rotor sleeves 163, 165 and on which a balancing area 234 is located.
  • the Fig. 12 shows an enlarged section of the Fig. 4 . It includes, like the Fig. 11 the same area near the labyrinth seal 223.
  • the rotor hub 161 has a Fig. 11 recognizable surface section 225, which has undergone a surface treatment in order to locally increase the emissivity. In the In the present embodiment, it is arranged in the radial direction between the labyrinth seal 223 and the Holweck rotor sleeve 165.
  • the surface section 225 may have been treated with at least one of the methods described above and/or may have a coating.
  • the coating if provided—may itself have an emissivity-enhancing effect and/or protect a roughening or structuring of the section 225.
  • the thermal radiation was measured by a Fig. 12 visible infrared sensor 227, but also which is arranged on the cap-like wall 221. In the Fig. 11 There was no representation of the infrared sensor 227, although it is also present there.
  • Section 225 is a flat, annular surface area extending in a plane substantially perpendicular to a rotation axis 151 of rotor 149.
  • sensor 227 statically arranged with wall 221, continuously receives a portion of the thermal radiation emitted by section 225, allowing continuous temperature measurement. In a thermal equilibrium state, the measured signal should exhibit only minor fluctuations.
  • the section 225 can comprise separate subsections, which in particular are evenly distributed circumferentially to minimize the imbalance they generate.
  • the section 225 is arranged downstream of the pumping stage formed by the rotor disks 155 and stator disks 157 in the pumping direction in order to minimize the effects of any outgassing that could occur due to the surface treatment.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
EP25164817.6A 2025-03-19 2025-03-19 Pompe à vide optimisée en termes de technique d'écoulement et de température Pending EP4549740A3 (fr)

Priority Applications (1)

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EP25164817.6A EP4549740A3 (fr) 2025-03-19 2025-03-19 Pompe à vide optimisée en termes de technique d'écoulement et de température

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EP25164817.6A EP4549740A3 (fr) 2025-03-19 2025-03-19 Pompe à vide optimisée en termes de technique d'écoulement et de température

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4108931A1 (fr) 2022-09-01 2022-12-28 Pfeiffer Vacuum Technology AG Pompe à vide moléculaire à puissance d'aspiration améliorée, ainsi que procédé permettant de faire fonctionner une pompe à vide moléculaire pour obtenir une puissance d'aspiration améliorée

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Publication number Priority date Publication date Assignee Title
NL8602052A (nl) * 1986-08-12 1988-03-01 Ultra Centrifuge Nederland Nv Hoogvacuumpomp.
JP3792318B2 (ja) * 1996-10-18 2006-07-05 株式会社大阪真空機器製作所 真空ポンプ
DE102011112689B4 (de) * 2011-09-05 2024-03-21 Pfeiffer Vacuum Gmbh Vakuumpumpe
DE102013209614A1 (de) * 2013-05-23 2014-11-27 Pfeiffer Vacuum Gmbh Verfahren zur Herstellung eines strukturierten Bauteils
DE202013008470U1 (de) * 2013-09-24 2015-01-08 Oerlikon Leybold Vacuum Gmbh Vakuumpumpe
DE202013009462U1 (de) * 2013-10-28 2015-01-29 Oerlikon Leybold Vacuum Gmbh Trägerelement für Rohrelemente einer Holweckstufe
DE102014105582A1 (de) * 2014-04-17 2015-10-22 Pfeiffer Vacuum Gmbh Vakuumpumpe
DE102014118881A1 (de) * 2014-12-17 2016-06-23 Pfeiffer Vacuum Gmbh Vakuumpumpe
GB2601313A (en) * 2020-11-25 2022-06-01 Edwards Ltd Drag pumping mechanism for a turbomolecular pump
EP3907406B1 (fr) * 2021-04-16 2023-05-03 Pfeiffer Vacuum Technology AG Pompe à vide
GB2607339A (en) * 2021-06-04 2022-12-07 Edwards Ltd Holweck drag pump

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4108931A1 (fr) 2022-09-01 2022-12-28 Pfeiffer Vacuum Technology AG Pompe à vide moléculaire à puissance d'aspiration améliorée, ainsi que procédé permettant de faire fonctionner une pompe à vide moléculaire pour obtenir une puissance d'aspiration améliorée

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