Vacuum pump with a holweck pumping stage with a varying holweck geometry

Abstract

The present invention relates to a vacuum pump with at least one Holweck pumping stage, comprising a Holweck stator and a Holweck rotor. The Holweck stator comprises a stator sleeve having a fixed end attached to a stationary housing section of the vacuum pump and a free end axially opposite the fixed end. The Holweck rotor comprises a rotor sleeve that surrounds the stator sleeve, forming a Holweck gap. According to the invention, the stator sleeve is formed in multiple parts.

Description

[0001] The present invention relates to a vacuum pump, also referred to here only as a pump, in particular a turbomolecular vacuum pump, according to the preamble of claim 1 with an internal Holweck pumping stage.

[0002] A vacuum pump of this type is essentially disclosed in EP 2 933 497 A2. A vacuum pump of essentially comparable type is also disclosed in EP 4 212 730 A1, although there the inner or internal stator sleeve is not formed in multiple parts. Further prior art is also disclosed in the publications EP 2 594 803 A1 and WO 2011 / 070 856 A1.

[0003] Vacuum pumps are used in various fields of technology. Depending on the requirements, vacuum pumps can have one or more pumping stages. Holweck pumping stages generally belong to the class of molecular vacuum pumps and generate a molecular flow by rotating a Holweck rotor relative to a stationary Holweck stator. In principle, a vacuum pump can comprise one or more Holweck pumping stages, with several Holweck pumping stages being able to be operated both in series and in parallel. Holweck pumping stages are typically used in turbomolecular vacuum pumps, where they are arranged downstream of one or more turbomolecular pumping stages in the direction of flow.

[0004] A Holweck pump typically comprises a Holweck rotor and a Holweck stator, with the Holweck rotor having a rotor shaft on which one or more Holweck rotor sleeves are concentrically mounted by means of a disc-shaped Holweck hub, for example. The Holweck hub and the Holweck rotor sleeve can be integral or one-piece; alternatively, the Holweck hub and the Holweck rotor sleeve can initially be separately manufactured parts that are subsequently joined together, for example by welding. A Holweck stator sleeve associated with the respective Holweck rotor sleeve is provided with a single- or multi-start Holweck thread and forms a Holweck gap with the respective Holweck rotor sleeve.The gas molecules to be pumped are conveyed by the rotating movement of the Holweck rotor relative to the Holweck stator along the threads from an inlet to an outlet of the respective Holweck pump stage. A thread comprises a spiral Holweck channel in the form of a thread groove, defined by the walls of a web, in which the gas molecules are conveyed when the rotor sleeve rotates relative to the stator sleeve.

[0005] Furthermore, so-called "folded" Holweck arrangements are known, in which several Holweck pump stages are arranged concentrically to one another and nested within one another, so that the pumping direction of radially immediately successive Holweck pump stages is opposite to one another. Two Holweck pump stages following one another in the direction of flow—a radially outer Holweck pump stage and a radially inner Holweck pump stage—can thus comprise a common Holweck stator sleeve, each provided with a Holweck thread on both sides and located radially between two rotor sleeves. The radially outer rotor sleeve can, in turn, be surrounded by an outer stator sleeve to form another Holweck pump stage together with the outer rotor sleeve.In contrast to the stator sleeve located radially outside the outer rotor sleeve, the stator sleeve located radially inside the outer rotor sleeve is consistently referred to as the inner stator sleeve in this context, even if it may not itself surround an inner rotor sleeve.

[0006] In principle, the Holweck geometry, and in particular the design of the Holweck thread, influences the parameters of the respective Holweck pump stage, such as its suction and / or compression capacity, as well as the power consumption of the pump motor. However, since the Holweck geometry typically does not change across the axial extent of a Holweck stator sleeve, these parameters can only be adjusted to a limited extent during pump design.

[0007] The invention is therefore based on the object of providing a vacuum pump of this type with greater design flexibility in pump design with regard to parameters such as suction and / or compression capacity and power consumption.

[0008] This object is achieved with a vacuum pump having the features of claim 1.

[0009] The stator sleeve can therefore be composed of several sleeve sections that can be handled separately during production and are arranged axially one behind the other or directly adjacent to each other. The individual sleeve sections can differ, for example, in the number of webs or the number of threads formed by the webs, allowing the relevant parameters to be specifically influenced.

[0010] Specifically, the inner or internal stator sleeve comprises a first sleeve portion having a first end and a second end opposite the first end, and at least one second sleeve portion, also having a first end and a second end opposite the first end. The first end of the first sleeve portion is attached to the stationary housing portion of the vacuum pump and thus forms the fixed end of the stator sleeve. The first end of the second sleeve portion, in contrast, is attached to the second end of the first sleeve portion. Thus, the second end of the second sleeve portion forms the free end of the stator sleeve, provided that no further sleeve portion is attached to the second end of the second sleeve portion.

[0011] Because the stator sleeve is composed of multiple sleeve sections, the first sleeve section, for example, can be characterized by a thread geometry that differs from the thread geometry of the second sleeve section. Sleeve sections with a wide variety of thread geometries can thus be kept in stock, which can then be combined to form a Holweck stator as required, in order to specifically model the suction and / or compression capacity of the Holweck pump stage. It is also possible, for example, to replace the first and / or second sleeve section with another sleeve section with a different thread geometry, thereby modifying the characteristics of an existing vacuum pump.

[0012] If different thread geometries are mentioned above, this refers to the external thread and any internal thread of the stator sleeve, which is formed by a plurality of thread grooves delimited by webs formed on the stator sleeve and by a groove base formed by the stator sleeve. The external thread of the first sleeve section can differ from the external thread of the second sleeve section in at least one thread parameter, wherein the at least one thread parameter is selected from the group of thread parameters consisting of the number of webs, the thread pitch, the width of the thread grooves, the width of the webs, and the height of the webs above the groove base.

[0013] In order to be able to interchange the individual sleeve sections or replace them with other sleeve sections, it is provided according to the invention that the first end of the first sleeve section has a first end contour and the first end of the second sleeve section has a first end contour that corresponds to the first end contour of the first sleeve section. Additionally or alternatively, it is provided that the second end of the first sleeve section has a second end contour and the second end of the second sleeve section can have a second end contour that corresponds to the second end contour of the first sleeve section. In other words, the first end contours can each be shaped essentially identically and the second end contours can also each be shaped essentially identically.Therefore, if the first sleeve section is attached with its first end to the stationary housing section, the second sleeve section can also be attached with its first end contour to the stationary housing section if necessary due to the fact that the first end contour of the second sleeve section corresponds to the first end contour of the first sleeve section.

[0014] To further promote the interchangeability of the individual sleeve sections, according to a further embodiment, it can further be provided that the first end of the first sleeve section has a first end contour and the second end of the second sleeve section has a second end contour that is complementary to the first end contour of the first sleeve section. Likewise, the first end of the second sleeve section can have a first end contour and the second end of the first sleeve section can have a second end contour that is complementary to the first end contour of the second sleeve section. The respective first end contour of one sleeve section thus matches the respective second end contour of the other sleeve section, so that the two sleeve sections can be combined to form a uniform stator sleeve.

[0015] Since the first end contour of the first sleeve section is formed complementarily to the second end contour of the second sleeve section, in the event that, instead of the first sleeve section, the second sleeve section is attached with its first end contour to the stationary housing section in the manner described above, the first sleeve section can be attached with its first end contour to the second end contour of the second sleeve section.Although in the initial state of the vacuum pump the first sleeve section is attached to the stationary housing section of the vacuum pump and the second sleeve section is attached to the second end of the first sleeve section, the two sleeve sections can thus be exchanged such that the second sleeve section is attached with its first end contour to the stationary housing section and the first sleeve section is attached with its first end contour to the second end contour of the second sleeve section.

[0016] According to a further embodiment, it can be provided that the respective first end contour has a first annular end face and a second annular end face, which is set back in the axial direction relative to the first annular end face. Likewise, the respective second end contour can have a first annular end face and a second annular end face, which is set back in the axial direction relative to the first annular end face. The annular first and second end faces are arranged coaxially to one another and thus each form a stepped end contour.

[0017] In the event that the first annular end face surrounds the second annular end face at the first end contour, the second end face surrounds the first end face at the second end contour due to the fact that the first end contour is complementary to the second end contour. This also means that the distance between the first end face of the first end contour and the second end face of the second end contour corresponds to the distance between the second end face of the first end contour and the first end face of the second end contour.

[0018] As already explained above, the respective second end face can be set back in the axial direction relative to the first end face of the respective end contour. However, since the first end face surrounds the second end face at the first end contour, whereas the second end face surrounds the first end face at the second end contour, this means that the first end face of the first end contour is connected to the second end face of the first end contour via an inner cylinder surface, and that the first end face of the second end contour is connected to the second end face of the second end contour via an outer cylinder surface.

[0019] Although the complementary shape of the respective end contours allows the individual sleeve sections to be precisely connected to one another in the manner described above, according to a preferred embodiment, the outer cylinder surface of the second end contour can also have a slightly larger diameter than the outer cylinder surface of the first end contour. The two sleeves can thus be connected to one another via a press fit along the outer cylinder surface of the second end contour and the inner cylinder surface of the first end contour.

[0020] Alternatively, it would be equally possible to provide an internal thread along the cylinder inner surface in question and an external thread along the cylinder outer surface in question, which mates with the aforementioned internal thread in order to be able to screw the individual sleeve sections together.

[0021] The invention is described below by way of example using advantageous embodiments with reference to the attached figures. They show, schematically: Fig. 1a perspective view of a turbomolecular pump, Fig. 2a view of the underside of the turbomolecular pump of Fig. 1 , Fig. 3 a cross-section of the turbomolecular pump along the Fig. 2 shown section line AA, Fig. 4 a cross-sectional view of the turbomolecular pump along the Fig. 2 shown section line BB, Fig. 5 a cross-sectional view of the turbomolecular pump along the Fig. 2 shown section line CC, and Fig. 6 a schematic cross-sectional view to explain the inventive design of the inner Holweck stator sleeve.

[0022] The Fig. 1The 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.

[0023] 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. In addition, a data interface 129, e.g., according to the RS485 standard, and a power supply connector 131 are arranged on the electronics housing 123.

[0024] There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

[0025] 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. In the area of ​​the lower part 121, a sealing gas connection 135, which is also referred to as a purge gas connection, is also 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. Furthermore, two 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.

[0026] 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. However, the vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and thus operated in a suspended position. Furthermore, 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.

[0027] Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in an upright position.

[0028] On the underside 141, which is Fig. 2As shown, various screws 143 are arranged, by means of which components of the vacuum pump (not further specified here) are fastened together. For example, a bearing cover 145 is attached to the underside 141.

[0029] 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.

[0030] In the Figures 2 to 5 a coolant line 148 is shown in which the coolant introduced and discharged via the coolant connections 139 can circulate.

[0031] As the sectional views of the Figures 3 to 5 show, 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.

[0032] A rotor 149 is arranged in the housing 119 and has a rotor shaft 153 rotatable about a rotation axis 151.

[0033] 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.

[0034] 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 (not shown) exist that do not have Holweck pump stages.

[0035] 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.

[0036] 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.

[0037] At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. Furthermore, at the upper end of the inner Holweck stator sleeve 169, a radially extending channel can be provided, via which the central Holweck gap 173 is connected to the radially inner Holweck gap 175. This connects the nested Holweck pump stages in series. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0038] 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.

[0039] For the rotatable mounting of the rotor shaft 153, 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.

[0040] In the area of ​​the rolling bearing 181, 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. In other existing turbomolecular vacuum pumps (not shown), 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.

[0041] The operating fluid storage comprises several stacked absorbent discs 187 which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

[0042] During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the operating fluid reservoir via the wiper to the rotating injection nut 185. As a result of centrifugal force, it 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.

[0043] 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 outward and the stator-side ring magnets 197 being arranged radially inward. 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 radially outward.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.

[0044] Within the magnetic bearing, an emergency or backup bearing 215 is provided, 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 collision of the rotor-side structures 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, causing the backup bearing 215 to be disengaged 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 collision of the rotor-side structures with the stator-side structures is prevented under all circumstances.

[0045] 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. Between the motor stator 217 and the portion of the rotor 149 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.

[0046] 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.

[0047] Furthermore, 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.

[0048] In the following, with reference to the Fig. 6 an inner Holweck stator sleeve 10 designed according to the invention is explained, which can be installed in the turbomolecular vacuum pump 111 instead of the stator sleeve 169 shown, wherein, however, the other structure of the turbomolecular vacuum pump 111 as well as the basic structure of the Holweck pump stage with three nested pump stages can be retained.

[0049] At the Fig. 6 In the embodiment shown, the inner stator sleeve 10 has a substantially hollow cylindrical shape with a free end 16 and an axially opposite fixed end 14, which is fastened here to a stationary housing section 12 of the vacuum pump 111, for example by means of a press-fit connection. Even if this is not the case here in the Fig. 6not shown, the stator sleeve 10 is concentrically surrounded by a rotor sleeve forming a Holweck gap, which means that the stator sleeve 10 is an internal or inner stator sleeve 10.

[0050] As the representation of the Fig. 6can be easily removed, the stator sleeve 10 is designed in several parts or in a modular manner and, in the embodiment shown here, is composed of a first hollow cylindrical sleeve section 18 and a second hollow cylindrical sleeve section 20, although it can also be provided that the stator sleeve 10 is composed of more than two, for example three, four or even more sleeve sections. Even if this is not shown here, the individual sleeve sections 18, 20 each have an external thread, wherein the external thread of the first sleeve section 18 differs from the external thread of the second sleeve section 20 in at least one thread parameter. In addition, the two sleeve sections 18, 20 can each have a different axial length.The thread parameters in question may be, for example, the number of lands forming the individual thread grooves, the thread pitch, the width of the thread grooves, the width of the lands and / or the height of the lands above the groove base or the outer surface of the respective sleeve section 18, 20.

[0051] The first sleeve section 18 has a first end 22 and a second end 24 opposite the first end 22. Correspondingly, the second sleeve section 20 has a first end 26 and a second end 28 opposite the first end 26. The first end 22 of the first sleeve section 18 is the end of the first sleeve section 18 that is attached to the stationary housing section 12 and thus corresponds to the fixed end 14 of the stator sleeve 10. In contrast, the first end 26 of the second sleeve section 20 is the end of the second sleeve section 20 via which the second sleeve section 20 is attached to the second end 24 of the first sleeve section 20. Accordingly, the second end 28 of the second sleeve portion 20 forms the free end 16 of the stator sleeve 10, provided that no further sleeve portion adjoins the second sleeve portion 20 in the axial direction.

[0052] Again Fig. 6 As can further be seen, the first ends 22, 26 of the first and second sleeve sections 18, 20 each form a first stepped end contour 30, wherein the first end contour 30 of the first sleeve section 18 is identical to the first end contour 30 of the second sleeve section 20. In a corresponding manner, the second ends 24, 28 of the first and second sleeve sections 18, 20 each form a second stepped end contour 32, wherein the second end contour 32 of the first sleeve section 18 is identical to the second end contour 32 of the second sleeve section 20. Apart from the design of the respective external threads and, if applicable, the axial length extension, the two sleeve sections 18, 20 are thus essentially identical.

[0053] In order to be able to attach the second sleeve portion 20 to the first sleeve portion 18, the first end contour 30 of the second sleeve portion 20 is configured to be substantially complementary to the second end contour 32 of the first sleeve portion 18. The first end 26 of the second sleeve portion 20 thus fits substantially positively with the second end 24 of the first sleeve portion 18.

[0054] In order to be able to interchange the arrangement of the two sleeve sections 18, 20 if necessary, the first end contour 30 of the first sleeve section 18 is designed to be substantially complementary to the second end contour 32 of the second sleeve section 20. The second sleeve section 20 can thus be attached to the stationary housing section 12 via its first end contour 30, whereas the first sleeve section 18 can then be attached with its first end contour 30 to the second end contour 32 of the second sleeve section 20.

[0055] As already mentioned, the two end contours 30, 32 are stepped and each have a first annular end face 34 and a second annular end face 36, which is set back in the axial direction relative to the first annular end face 34. The second annular end face 36 is the end face of the respective end contour 30, 32 which is set back in the axial direction relative to the first end face 36. However, at the first end contour 30, the first annular end face 34 surrounds the second annular end face 36, whereas at the second end contour 32, the second annular end face 36 surrounds the first annular end face.

[0056] Due to the fact that the radial position of the two end faces 34, 36 at the opposite ends of the respective sleeve section 18, 20 is swapped, the distance at the respective sleeve section 18, 20 between the first end face 34 of the first end contour 30 and the second end face 36 of the second end contour 32 is in each case the same size as the distance between the second end face 36 of the first end contour 30 and the first end face 34 of the second end contour 32.

[0057] Due to the previously explained stepped design of the respective end contours 30, 32, a cylinder inner surface 38 extends between the first end face 34 of the first end contour 30 and the second end face 36 of the first end contour 30, whereas a cylinder outer surface 40 extends between the first end face 34 of the second end contour 32 and the second end face 36 of the second end contour 32.

[0058] In this case, the respective cylinder outer surface 40 can have a certain radial oversize relative to the respective cylinder inner surface 38 in order to be able to connect the sleeve sections 18, 20 to one another by means of a press-fit connection effective along the two cylinder surfaces 38, 40. Alternatively, it can be provided to form an internal thread on the respective cylinder inner surface 38 and an external thread matching the internal thread on the respective cylinder outer surface 40 in order to be able to screw the sleeve sections 18, 20 together.

[0059] Due to the identical or complementary design of the sleeve sections 18, 20 with regard to the respective end contours 30, 32, these can be interchanged with one another if necessary or replaced by appropriately designed sleeve sections with a possibly different Holweck thread geometry, which provides greater design flexibility in the pump design with regard to parameters such as the suction and / or compression capacity as well as the power consumption. List of reference symbols

[0060] 10 Stator sleeve 12 Stationary housing section 14 Fixed end 16 Free end 18 First sleeve section 20 Second sleeve section 22 First end of 18 24 Second end of 18 26 First end of 20 28 Second end of 20 30 First end contour 32 Second end contour 34 First end face (circular) 36 Second end face (circular) 38 Cylinder inner surface 40 Cylinder outer surface 111 Turbomolecular pump 113 Inlet flange 115 Pump inlet 117 Pump outlet 119 Housing 121 Base 123 Electronics housing 125 Electric motor 127 Accessory connection 129 Data interface 131 Power supply connection 133 Vent inlet 135 Seal gas connection 137Engine compartment 139Coolant connection 141Underside 143Screw 145Bearing cover 147Mounting hole 148Coolant line 149Rotor 151Rotation axis 153Rotor shaft 155Rotor disc 157Stator disc 159Spacer ring 161Rotor hub 163Holweck rotor sleeve 165Holweck rotor sleeve 167Holweck stator sleeve 169Holweck stator sleeve 171Holweck gap 173Holweck gap 175Holweck gap 179Connecting channel181Rolling bearing 183Permanent magnetic bearing 185Injection nut 187Disk 189Insert 191Rotor-side bearing half 193Stator-side bearing half 195Ring magnet 197Ring magnet 199Bearing gap 201Support section 203Support section 205Radial strut 207Cover element 209Support ring 211Fastening ring 213Disc spring 215Emergency or safety bearing 217Motor stator 219Gap 221Wall 223Labyrinth seal

Claims

1. A vacuum pump (111), in particular a turbomolecular vacuum pump (111), comprising at least one Holweck pump stage which comprises a Holweck stator and a Holweck rotor; wherein the Holweck stator comprises a stator sleeve (10, 169) which is formed in multiple parts and which has a fixed end (14) attached to a stationary housing section (12) of the vacuum pump (111) and a free end (16) disposed opposite the fixed end (14) in the axial direction; wherein the Holweck rotor comprises a rotor sleeve (163) which surrounds the stator sleeve (10, 169) while forming a Holweck gap (173), characterized in that the stator sleeve (10, 169) comprises a first sleeve section (18), which has a first end (22) and a second end (24) disposed opposite the first end (22), and at least a second sleeve section (20), which has a first end (26) and a second end (28) disposed opposite the first end (26), wherein the first end (22) of the first sleeve section (18) is attached to the stationary housing section (12) and the first end (26) of the second sleeve section (20) is attached to the second end (24) of the first sleeve section (18); and further characterized in that the first end (22) of the first sleeve section (18) has a first end contour (30) and the first end of the second sleeve section (20) has a first end contour (30) which corresponds to the first end contour (30) of the first sleeve section (18); and / or in that the second end (24) of the first sleeve section (18) has a second end contour (32) and the second end (28) of the second sleeve section (20) has a second end contour (32) which corresponds to the second end contour (32) of the first sleeve section (18).

2. A vacuum pump (111) according to claim 1, characterized in that the first end (22) of the first sleeve section (18) has a first end contour (30) and the second end of the second sleeve section (20) has a second end contour (32) which is formed in a complementary manner to the first end contour (30) of the first sleeve section (18); and / or the first end (26) of the second sleeve section (20) has a first end contour (30) and the second end of the first sleeve section (18) has a second end contour (32) which is formed in a complementary manner to the first end contour (30) of the second sleeve section (20).

3. A vacuum pump (111) according to claim 1 or 2, characterized in that the respective first end contour (30) has a first end face (34) and a second end face (36) which is set back in the axial direction with respect to the first end face (34); and / or the respective second end contour (32) has a first end face (34) and a second end face (36) which is set back in the axial direction with respect to the first end face (34).

4. A vacuum pump (111) according to claim 3, characterized in that the spacing between the first end face (34) of the first end contour (30) and the second end face (36) of the second end contour (32) corresponds to the spacing between the second end face (36) of the first end contour (30) and the first end face (34) of the second end contour (32).

5. A vacuum pump (111) according to claim 3 or 4, characterized in that the first end face (34) of the first end contour (30) is connected to the second end face (36) of the first end contour (30) via an inner cylinder surface (38) and the first end face (34) of the second end contour (32) is connected to the second end face (36) of the second end contour (32) via an outer cylinder surface (40) which has a larger diameter than the inner cylinder surface (38) of the first end contour (30).

6. A vacuum pump (111) according to any one of the preceding claims, characterized in that an external thread having a plurality of thread grooves is formed at the stator sleeve (10, 169), which thread grooves are bounded by webs formed at the stator sleeve (10, 169) and by a groove base formed by the stator sleeve (10, 169), with the external thread of the first sleeve section (18) differing in at least one thread parameter from the external thread of the second sleeve section (20), with the at least one thread parameter being selected from the group of thread parameters that consists of the number of webs, the thread pitch, the width of the thread grooves, the width of the webs and the height of the webs above the groove base.

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