Adjusting ring

Abstract

The invention relates to an adjusting ring with an adjusting section for the axial alignment of a radially inner first bearing section of a bearing of a vacuum pump, in particular a turbomolecular pump, in the direction of a longitudinal central axis of the bearing relative to a radially outer second bearing section of the bearing of the vacuum pump, characterized in that a circumferential collar extends from the adjusting section of the adjusting ring, which has a radially outwardly extending radial collar section. Furthermore, the invention relates to a bearing for a vacuum pump with such a bearing and to a vacuum pump with such a bearing.

Description

[0001] The present invention relates to an adjusting ring with an adjusting section for the axial alignment of a radially inner first bearing section of a bearing of a vacuum pump, in particular a turbomolecular pump, in the direction of a longitudinal center axis of the bearing relative to a radially outer second bearing section of the bearing of the vacuum pump.

[0002] Such an adjusting ring for a bearing of a vacuum pump is generally known. For example, an adjusting ring with the features of the preamble of claim 1 is disclosed in EP 3 018 373 A1. Furthermore, JP S64 45032 U also teaches an adjusting ring for a bearing of a vacuum pump. DE 20 2009 013 629 U1 discloses a vacuum pump in which a retaining sleeve has a radially extending shoulder and several axially extending extensions. EP 3 106 668 A1 and DE 10 2013 218 220 A1 each relate to a vacuum pump with an adjusting ring for a bearing.

[0003] The bearing serves to support a vacuum pump rotor that rotates around a rotational axis relative to a stator. It typically consists of two bearing sections, one of which is arranged radially inside the other. One bearing section is assigned to the stator, and the other to the rotor. Radially between the bearing sections is a space, also known as the bearing gap.

[0004] Over time, unwanted foreign bodies, such as particles, can enter the gap and settle there, which can lead to increased friction between the bearing sections and, as a result, higher power consumption, as well as premature wear of the bearing and, in the worst case, to a total failure of the vacuum pump.

[0005] For high-vacuum applications, lubricant-free bearings, such as magnetic bearings, are primarily used to support the rotor on the vacuum side to prevent lubricant contamination of the vacuum chamber. A magnetic bearing comprises at least one pair of magnets, in particular permanent magnets, with the stator-side bearing section and the rotor-side bearing section each comprising one magnet of the magnet pair.

[0006] The magnets of the magnetic bearing generate a static magnetic stray field both when the vacuum pump is idle and a dynamic, i.e., time-varying, magnetic stray field during operation, which additionally superimposes the static magnetic stray field. The dynamic magnetic stray field is essentially emitted at the rotor's rotational frequency and is due to unavoidable, manufacturing-related local variations in the magnetic field strength and field orientation of the magnets in the rotor-side bearing section.

[0007] The static and / or dynamic stray magnetic field can affect highly sensitive applications, for example, by deflecting an electron beam of an electron microscope due to the Lorentz force, which can lead to imaging errors or a reduction in the resolving power of the electron microscope. The stray magnetic field can also affect the magnetization of a highly sensitive magnetic thin film deposited under vacuum.

[0008] During operation of the vacuum pump in an environment with, particularly strong, magnetic field sources, eddy currents can be induced in the rotating rotor. These eddy currents lead to a deceleration of the rotor, so that an increased power requirement is necessary to maintain a certain rotor speed. Furthermore, the eddy currents cause the rotor to heat up, which can noticeably reduce the bearing gap due to thermal expansion. In the worst case, the thermal expansion of the rotor can be so severe that the rotor, especially if the bearing gap is small, comes into contact with the stator and is consequently decelerated. This can cause the vacuum pump to come to a complete standstill or even be damaged. One object of the invention is to provide a method for protecting a bearing gap from contamination and to provide magnetic field shielding.

[0009] The object is achieved by an adjusting ring having the features of claim 1 and in particular in that a circumferential collar emerges from the adjusting section of the adjusting ring, which has a radial collar section extending radially outward, wherein an axial collar section emerges at an angle from the radial collar section.

[0010] The invention is based on the general idea of expanding an already existing adjusting ring for the axial alignment of a first bearing section with respect to a second bearing section of a bearing to include a protective function for a bearing gap between the bearing sections against contamination, i.e., against the deposition of foreign bodies, by providing the adjusting ring with a circumferential collar which emerges from an adjusting section of the adjusting ring and which has a radially outwardly extending radial collar section. As a result, at most a minimal, in particular harmless, amount of foreign bodies enters the bearing gap; at best, the penetration of foreign bodies into the bearing gap is completely prevented.This results in the advantage of a longer bearing service life and lower power consumption, as less friction occurs due to the reduced number of foreign bodies between the bearing sections. A further advantage is that the radial collar section of the adjusting ring enables at least partial, and ideally complete, magnetic shielding of the rotor from external magnetic fields and / or, conversely, protection of magnetically sensitive applications from the stray magnetic field of a magnetic bearing used for support.

[0011] In this context, the axial alignment of one bearing section with respect to the other bearing section refers to the alignment of the two bearing sections relative to each other in the direction of the longitudinal center axis of the bearing. In particular, the longitudinal center axis of the bearing can correspond to the rotational axis of the rotor.

[0012] It should be noted that the adjusting ring is not limited to use in vacuum pumps, but can basically be used anywhere where axial alignment of two bearing sections of a bearing is required and protection against contamination or shielding from magnetic fields is desirable.

[0013] Advantageous embodiments of the invention can be found in the dependent claims, the description and the drawings.

[0014] The adjusting ring can have an at least approximately circular circumferential profile and be manufactured from a round steel bar, in particular a round steel bar made of stainless steel, by a machining process such as turning or milling. The adjusting ring is preferably manufactured from a single piece, so that the adjusting section and collar of the adjusting ring are formed integrally. However, it is also conceivable for the adjusting section and the collar to be separate components that are joined together to form the adjusting ring, for example by shrinking, gluing, soldering, welding, or the like. Furthermore, it is also conceivable for the adjusting section and the radial collar section to be separate components that are joined together to form the adjusting ring.

[0015] The adjustment ring can have not only an at least approximately circular circumferential profile, but also any other circumferential profile, such as a polygonal circumferential profile. A hexagonal circumferential profile can be particularly advantageous, as it allows the adjustment ring to be rotated particularly easily using a tool, in particular an open-end wrench.

[0016] It is understood that the adjusting ring can be made not only from round steel, but also from any other metallic material or another suitable material, such as a plastic or ceramic. Furthermore, the adjusting section and the collar can be made of different materials. Furthermore, it is also conceivable that the adjusting section and / or the radial collar section can be made of different materials.

[0017] For even better magnetic shielding of the rotor against external magnetic fields and / or the environment of the vacuum pump against a magnetic stray field or magnetic field generated by a magnetic bearing for supporting the rotor, it is advantageous if the adjusting ring comprises at least in sections a ferromagnetic, in particular soft magnetic, and / or electrically conductive material.

[0018] With the help of the ferromagnetic material, both static and dynamic magnetic fields can be reliably shielded. The ferromagnetic material is characterized by a relative magnetic permeability that is significantly greater than 1. The ferromagnetic material preferably comprises at least one of the metals iron (Fe), nickel (Ni), cobalt (Co), or an alloy of at least two of these metals. Alloys of aluminum / nickel / cobalt (Al / Ni / Co) or samarium / cobalt (Sm / Co) are also conceivable. Instead of the ferromagnetic material, however, a ferrimagnetic ceramic material, such as ferrite, can also be used. In general, the higher the magnetic permeability of the material from which the adjustment ring is made, the better the magnetic shielding.

[0019] Additionally or alternatively, the adjusting ring may comprise an electrically conductive, in particular a diamagnetic or paramagnetic, material, such as copper, aluminum, non-ferromagnetic alloys of copper and / or aluminum or non-ferromagnetic steels.

[0020] The advantage of using an electrically conductive, particularly non-ferromagnetic, material is that it allows for particularly effective shielding of the dynamic magnetic fields generated by the rotating rotor, which are primarily disruptive to magnetically sensitive applications. Magnetic shielding is based on induction effects induced in the electrically conductive material by the alternating magnetic field. These effects depend on the frequency of the dynamic magnetic field or alternating magnetic field, as well as on the specific internal electrical resistance of the electrically conductive material. A further advantage of using electrically conductive, particularly non-ferromagnetic, materials is that, compared to ferromagnetic materials, more and / or more cost-effective and / or more resistant materials to the gases to be pumped away are available.

[0021] Furthermore, it should be noted that the magnetic shielding effect of the adjustment ring means that, at best, additional magnetic shielding can be dispensed with, so that the number of components can be reduced and / or material and manufacturing costs can be saved.

[0022] To improve the protective function against contamination and / or the shielding against magnetic fields, the adjusting ring according to the invention further comprises an axial collar section, which protrudes at an angle from the radial collar section. In principle, the adjusting section and / or the radial collar section and / or the axial collar section can be made of different materials. It is understood that the adjusting section and the radial and axial collar sections can also be formed integrally with one another. Alternatively, the adjusting section and / or the radial collar section and / or the axial collar section can be separate components joined together to form the adjusting ring.

[0023] Preferably, the axial collar section emerges from the radial collar section at a radially outer edge region of the latter.

[0024] In order to preload and / or fix the stator-side bearing section in the axial direction, a spring element can be arranged between the adjustment section of the adjustment ring and the stator-side bearing section of the bearing, as viewed in the axial direction. It is also conceivable for the adjustment section to comprise a plurality of components stacked one above the other in the axial direction for the purpose of axial preload and / or fixation of the stator-side bearing section, wherein, as viewed in the axial direction, at least one spring element can be arranged between at least two components of the stack of components forming the adjustment section. It is understood that the radial collar section can emerge from one of the components of the stack.

[0025] If the adjusting section comprises at least two components stacked axially one above the other and the radial collar section emerges from one of the components, the or each component of the adjusting section without a radial collar section and the component with a radial collar section can be rotated relative to one another. In this case, the radial collar section can have at least one bore penetrating the radial collar section, so that the or each component of the adjusting section without a radial collar section is freely accessible. As a result, the or each component of the adjusting section without a radial collar section can be rotated relative to the component with a radial collar section, for example with the aid of a tool, in order to align the stator-side bearing section in the axial direction with respect to the rotor-side bearing section by rotating the or each component without a collar section.In principle, the components of the adjustment section with and without a radial collar section can also be connected to one another, in particular connected to one another in a rotationally secure manner, in such a way that a rotation of the radial and / or axial collar section causes a rotation of the or each component of the adjustment section without a radial collar section.

[0026] The protective function against contamination and / or the shielding against magnetic fields can be further improved if the adjusting ring has, in addition to the radial collar section and / or axial collar section just described, further radial and / or axial collar sections. Preferably, at least one further radial collar section and / or one further axial collar section emerges from the aforementioned radial or axial collar section. Advantageously, several radial and axial collar sections alternate. Several radial and axial collar sections can alternate in such a way that the entirety of the collar sections has a rectangular modulation when viewed in cross-section. A step-like modulation of several radial and axial collar sections is also conceivable.Furthermore, two axial collar sections can emerge from a radial collar section at an angle such that the two axial collar sections point in opposite directions, i.e. the radial collar section and the two axial sections essentially correspond to a T or Y tilted by approximately 90°. In a corresponding manner, two radial collar sections can also emerge from one axial collar section. In particular, the adjusting ring can have a circumferential collar which emerges from an adjusting section of the adjusting ring, wherein the circumferential collar has a first radial collar section extending radially outwards and, emerging therefrom, an angled axial collar section and a second radial collar section which extends the first radial collar section radially outwards. Such an adjusting ring has, in a sense, a T-shaped collar.The advantage of an adjusting ring designed in this way is stronger magnetic shielding by the first and second radial collar sections and better protection against contamination by the axial and first radial collar sections.

[0027] According to an advantageous embodiment, the radial collar section has a smaller axial dimension than the adjustment section, i.e. the radial collar section is thinner than the adjustment section when viewed in the direction of the longitudinal center axis of the bearing. Additionally or alternatively, the axial collar section and the adjustment section can have at least approximately the same axial dimensions, or in other words, the adjustment section and the axial collar section are at least approximately the same length when viewed in the direction of the longitudinal center axis of the bearing. It is understood that the adjustment section and the axial section can in principle also have different axial dimensions. If the adjustment ring comprises a plurality of radial and / or axial collar sections, the axial dimensions of all radial collar sections and / or all axial collar sections can be at least approximately the same.It is understood, however, that at least two radial and / or two axial collar sections may have different axial dimensions.

[0028] The invention also relates to a bearing for a vacuum pump, in particular a turbomolecular pump, having a radially inner first bearing section, a radially outer second bearing section, and an adjusting ring which serves to axially align the first bearing section relative to the second bearing section in the direction of the longitudinal center axis of the bearing. The bearing according to the invention is characterized in that the radially extending collar section spans the second bearing section in the radial direction. If the adjusting ring has an axial collar section, the second bearing section is arranged between the adjusting section and the axial collar section of the adjusting ring, viewed in the radial direction.

[0029] A particularly good protective effect against undesired deposition of foreign bodies in the bearing gap can be achieved if the axial collar section partially overlaps axially with the second bearing section.

[0030] According to an advantageous embodiment, the bearing comprises a locking ring for locking the second bearing section, which, viewed in the radial direction, is arranged at least in sections between the adjustment section and the axial collar section.

[0031] The protective effect of the adjusting ring can be further enhanced if the locking ring and the adjusting ring define an annular gap with a multi-angled cross-section. The annular gap forms a labyrinth in which foreign objects can become trapped before reaching the bearing gap.

[0032] At this point, it should be noted that the or each radial collar section and / or the or each axial collar section of the adjusting ring can be configured such that, together with the adjusting ring or the second bearing section spanned in the radial direction by a radial section, a pumping effect is achieved. For example, at least one of the collar sections can have groove-like, in particular spiral-groove-like, structures, which, together with the locking ring or the second bearing section spanned by the adjusting ring, form a pumping system based on the Holweck and / or Siegbahn pumping principle.Preferably, the pumping action of such a pumping system is such that the gas conveying direction is directed away from the bearing gap in order to counteract an undesired foreign body with a counterflow, so that the foreign body cannot enter the bearing gap or at least the penetration of the foreign body into the bearing gap is made more difficult.

[0033] According to a preferred embodiment, the bearing is a magnetic bearing, wherein the first and second bearing sections each comprise at least one magnet. The magnet can be a permanent magnet, in particular a monolithic permanent magnet.

[0034] Furthermore, the invention is directed to a vacuum pump having a rotor rotatably mounted relative to a stator and a bearing for mounting the rotor on the stator, wherein the stator is preferably arranged radially inside the rotor.

[0035] For axial alignment of the stator-side bearing section with respect to the rotor-side bearing section, the adjusting ring can be threadedly engaged with the stator, allowing the stator-side bearing section to be axially aligned with respect to the rotor-side bearing section by rotating the adjusting ring around the longitudinal center axis of the bearing. For this purpose, the stator and the adjusting ring have a complementary thread, whereby a particularly precise alignment of the stator-side and rotor-side bearing sections can be achieved through a fine thread.

[0036] The invention is described below purely by way of example using a possible embodiment with reference to the accompanying drawings. They show: Fig. 1 is a cross-sectional view of a turbomolecular pump with an adjusting ring not according to the invention; and Fig. 2 is a detailed view of the turbomolecular pump of Fig. 1with an adjustment ring according to the invention.

[0037] The Fig. 1 The turbomolecular pump 10 shown comprises a pump inlet 14 surrounded by an inlet flange 12 and a plurality of pump stages for conveying the gas present at the pump inlet 14 to a Fig. 1 Pump outlet (not shown). Arranged in a housing 16 of the turbomolecular pump 10 is a rotor 18 rotatable relative to a stator 17, with a rotor shaft 22 mounted rotatably about a rotation axis 20, the stator 17 being located radially within the rotor 18.

[0038] To generate a pumping effect, the turbomolecular pump 10 comprises a plurality of turbomolecular pump stages connected in series with one another for pumping purposes, with a plurality of rotor disks 24 fastened to the rotor shaft 22 and stator disks 26 arranged in the axial direction between the rotor disks 24. The stator disks 26 are held at a desired axial distance from one another by spacer rings 28.

[0039] Furthermore, three Holweck pump stages are provided, arranged radially one inside the other and connected in series for pumping purposes. The rotor-side part of the Holweck pump stages comprises a rotor hub 30 connected to the rotor shaft 22 and two cylindrical-shell-shaped Holweck rotor sleeves 32, 34 fastened to and supported by the rotor hub 30, which are oriented coaxially to the rotational axis 20 and nested one inside the other in the radial direction. Furthermore, two cylindrical-shell-shaped Holweck stator sleeves 36, 38 are provided, which are also oriented coaxially to the rotational axis 20 and nested one inside the other in the radial direction.

[0040] The pumping surfaces of the Holweck pump stages are each formed by the radial lateral surfaces of a Holweck rotor sleeve 32, 34 and a Holweck stator sleeve 36, 38, which are opposite one another to form a narrow radial Holweck gap. In each case, one of the pumping surfaces is smooth—predominantly that of the Holweck rotor sleeve 32, 34—and the opposite pumping surface of the Holweck stator sleeve 36, 38 has a structure with helical grooves extending in the axial direction around the rotation axis 20, in which grooves the gas is propelled and thus pumped during the rotation of the rotor 18.

[0041] The rotatable mounting of the rotor shaft 22 is effected by a rolling bearing 40 in the region of the pump outlet and in the region of the pump inlet 14 by a bearing 42, which in the illustrated embodiment is designed as a permanent magnet bearing 42.

[0042] The permanent magnet bearing 42 comprises a rotor-side bearing section 44 and a stator-side bearing section 46, each comprising a ring stack of a plurality of permanent magnet rings 48, 50 stacked one upon another in the axial direction, i.e., in the direction of a longitudinal center axis 47 of the permanent magnet bearing 42. The magnetic rings 48, 50 are opposite one another, forming a radial bearing gap 52. As can be seen from the figures, the longitudinal center axis 47 of the permanent magnet bearing 42 and the rotational axis 20 of the rotor 18 coincide.

[0043] The stator-side bearing section 46 forms a first bearing section 46 of the bearing 42, which is arranged radially inside the rotor-side bearing section 44 (second bearing section 44). For the axial alignment of the stator-side bearing section 46 with respect to the rotor-side bearing section 44, an adjusting ring 53 is provided which is in threaded engagement with the stator 17. The stator-side bearing section 46 can be axially aligned with respect to the rotor-side bearing section 44 by rotating the adjusting ring 53 about the rotation axis 20. Fig. 1 The adjusting ring 53 shown is a conventional adjusting ring 53, which according to the invention is replaced by an adjusting ring 84, as shown in Fig. 2 will be described later.

[0044] A rotation of the adjusting ring 53 such that the stator-side bearing section 46 is axially displaced toward the roller bearing 40 located in the area of the pump outlet causes an axial displacement of the stator-side bearing section 46 counter to the restoring force of a spring element 51, which here is formed by several disc springs stacked one above the other. However, the spring element 51 can also be, for example, a helical compression spring or any other spring element, which, upon the described rotation of the adjusting ring 53, counteracts a restoring force on the stator-side bearing section 46, which is thereby axially displaced toward the roller bearing 40.

[0045] The rotor-side bearing section 44 is held on the rotor 18 by a locking ring 55. The locking ring 55 has a holding section 57a for holding the magnetic rings 50 of the rotor-side bearing section 44 on the rotor 18. The holding section 57a is connected by means of a radially outwardly extending intermediate section 57b to a radially outwardly extending fastening section 57c of the locking ring 55. The fastening section 57c is, viewed in the circumferential direction, penetrated by a plurality of radially extending bores 59 which serve to receive locking screws (not shown here) for fastening the locking ring 55 to the rotor 18. Unlike in the Fig. 1 The locking ring 55 shown in Fig. 2The locking ring 55 shown has an intermediate section 57b which emerges from the holding section 57a and extends radially outwards and is axially angled in the direction of the rolling bearing 40, which in turn merges into the radially outwards extending fastening section 57c.

[0046] Coming back to Fig. 1 Within the magnetic bearing 42, an emergency or safety bearing 54 is provided. This bearing is designed as an unlubricated roller bearing and runs idle without contact during normal operation of the turbomolecular pump 10. It only engages upon excessive radial deflection of the rotor 18 relative to the stator, forming a radial stop for the rotor 18 that prevents a collision between the rotor-side structures and the stator-side structures. The emergency bearing 54 thus defines the maximum radial deflection of the rotor 18.

[0047] In the area of the rolling bearing 40, a conical injection nut 56 with an outer diameter increasing toward the rolling bearing 40 is provided on the rotor shaft 22. The injection nut 56 is in sliding contact with at least one wiper of a fluid reservoir comprising several stacked absorbent discs 58, which are impregnated with an operating fluid, such as a lubricant for the rolling bearing 40.

[0048] During operation of the turbomolecular pump 10, the operating fluid is transferred by capillary action from the operating fluid reservoir via the wiper to the rotating injection nut 56 and, as a result of the centrifugal force, is conveyed along the injection nut in the direction of the increasing outer diameter of the injection nut 56 to the rolling bearing 40, where it fulfills, for example, a lubricating function.

[0049] The turbomolecular pump 10 comprises a motor chamber 60 into which the rotor shaft 22 extends. The motor chamber 60 is sealed from a working or suction chamber of the turbomolecular pump 10 by a Siegbahn stage 62 in the area of the inlet of the rotor shaft 22. A sealing gas inlet 64 allows the supply of a sealing gas into the motor chamber 60.

[0050] In the motor compartment 60, a drive motor 66 is arranged, which serves to drive the rotor 18 in rotation. The drive motor 66 comprises a motor stator 68 with a core 70 and with a plurality of Fig. 1 only schematically illustrated coils 72, which are fixed in slots provided on the radial inside of the core 70. The core 70 consists of a laminated core with several laminated discs made of a soft magnetic material stacked one on top of the other in the axial direction.

[0051] The rotor of the drive motor 77, also referred to as the armature, is formed by the rotor shaft 22, which extends through the motor stator 68. A permanent magnet arrangement 74 is fixed radially outwardly on the portion of the rotor shaft 22 extending through the motor stator 68. A radial motor gap 76 is formed between the motor stator 68 and the portion of the rotor shaft 22 extending through the motor stator 68, via which the motor stator 68 and the permanent magnet arrangement 74 magnetically influence each other to transmit the drive torque.

[0052] The permanent magnet arrangement 74 is fixed to the rotor shaft 22 by means of gluing, shrinking, and / or pressing. The permanent magnet arrangement 74 comprises a soft magnetic return path 75a made of iron sheets or solid iron, as well as a permanent magnet 75b. An encapsulation 80, designed as a CFRP or stainless steel sleeve, surrounds the permanent magnet arrangement 74 on its radial outer side and seals it against the motor gap 76. Furthermore, a balancing ring 78 is attached to the rotor shaft 22 by means of gluing, shrinking, and / or pressing. The balancing ring 78 has threaded holes for receiving balancing weights. The balancing ring 78 has no direct mechanical connection to the permanent magnet arrangement 74 in order to prevent any axial constraining forces from being transferred to the permanent magnet arrangement 74.

[0053] A control and power supply unit 82 is configured to supply the drive motor 66 with electrical energy during operation of the turbomolecular pump 10.

[0054] Fig. 2 shows the adjustment ring 84 according to the invention, which can be used in functional terms instead of the conventional adjustment ring 53 described above.

[0055] The adjusting ring 84 according to the invention comprises an adjusting section 86 for the axial alignment of the stator-side bearing section 46 relative to the rotor-side bearing section 44. A radially circumferential collar 88 emerges from the adjusting section 86, which collar has a radially outwardly extending radial collar section 90 and an angled axial collar section 94 emerging from this at a radially outer edge region 92 of the radial collar section 90. In the illustrated embodiment, the adjusting section 86, the radial collar section 90 and the axial collar section 94 are formed in one piece. It is understood that the adjusting ring 84, in addition to the Fig. 2 illustrated radial and axial collar section 90, 94 may also have at least one further radial and / or axial collar section.

[0056] Viewed in the direction of the longitudinal center axis 47 of the permanent magnet bearing 42, the radial collar portion 90 has a smaller axial dimension than the adjustment portion 86. Moreover, the axial dimensions of the axial collar portion 94 and the adjustment portion 86 are at least approximately equal.

[0057] In the illustrated embodiment, the axial dimensions of the adjustment section 86 and the axial collar section 94 of the adjustment ring 84 are between 2 and 10 mm, preferably between 3 and 7 mm, and particularly preferably between 4 and 6 mm. The radial collar section 90 is dimensioned such that its axial dimension is between 0.5 and 2.5 mm, preferably between 0.7 and 2.0 mm, and particularly preferably between 0.8 and 1.5 mm. Furthermore, the adjustment ring 84 has an outer diameter of 45 to 55 mm, preferably from 47 to 53 mm, and particularly preferably from 49 to 50 mm. An adjustment ring 84 dimensioned in this way is used in a turbomolecular pump 10 with a rotor 18 whose outer diameter is approximately 160 mm. It is understood that the dimensions of the adjusting ring 84 may differ from the above-mentioned dimensions of the adjusting ring 84 depending on the size of the turbomolecular pump 10 or the rotor outer diameter.

[0058] For magnetic shielding of the rotor 18 from external magnetic fields and for protecting a recipient to be evacuated (not shown) from a magnetic field generated by the permanent magnet bearing 42, the adjusting ring 84 has at least one ferromagnetic, in particular soft magnetic, and / or an electrically conductive material.

[0059] As shown by Fig. 2As can be seen, the radial collar section 90 of the collar 88 spans the second bearing section 44 in the radial direction, whereas the axial collar section 94 of the collar 88 partially overlaps the second bearing section 44 in the axial direction. Specifically, the radial collar section 90 of the collar 88 spans the holding section 57a and the radially aligned component of the intermediate section 57b of the locking ring 55 provided for fastening the second bearing section 44 in the radial direction, whereas the axial collar section 94 of the collar 88 overlaps the axially angled component of the intermediate section 57b of the locking ring 55, so that the locking ring 55 is arranged in sections between the axial collar section 94 and the adjusting section 86 of the adjusting ring 84.More specifically, the holding portion 57a and the intermediate portion 57b of the locking ring 55 are arranged between the axial collar portion 94 and the adjusting portion 86 of the adjusting ring 84.

[0060] The above-described design of the collar 88 of the adjusting ring 84 allows for magnetic shielding where the magnetic field is generated by the permanent magnet bearing 42 or where shielding of the rotor 18 from external magnetic fields is relevant. At the same time, the adjusting ring 84 leaves the pumping-active area of the turbomolecular pump 10 formed by the rotor disks 24 and stator disks 26 free, so that the pumping action of the turbomolecular pump 10 is not impaired or only slightly impaired.

[0061] The adjustment ring 84 according to the invention eliminates the need for an additional magnetic shielding device, which would typically completely or almost completely cover the pump inlet 14 in the form of a grid. Thus, the adjustment ring 84 is more easily accessible for adjustment purposes via the pump inlet 14, which significantly simplifies the handling of the turbomolecular pump 10.

[0062] It is also possible to use Fig. 2It can be seen that the radial collar section 90 of the collar 88 and the radial component of the intermediate section 57b of the locking ring 55 as well as the axial collar section 94 of the collar 88 and the axial component of the intermediate section 57b of the locking ring 55 are arranged at least approximately parallel to one another, wherein the respective sections of the adjusting ring 84 are spaced from the corresponding sections of the locking ring 55, so that ultimately a labyrinth-like annular gap 96 with a multiply angled cross-section is formed between the adjusting ring 84 and the locking ring 55. Foreign bodies can become caught in the labyrinth-like annular gap 96 before they reach the bearing gap 52, so that the bearing gap 52 is particularly effectively protected against contamination by foreign bodies.

[0063] According to an advantageous development of the adjustment ring 84 (not shown), the circumferential collar 88 has a first radial collar section 90 extending from the adjustment section 86 and an axial collar section 94 extending at an angle therefrom. A second radial collar section also extends from the first radial collar section 90, so that the first radial collar section 90 is located radially inside the second radial collar section. As a result, the collar 88 of the adjustment ring 84 has a larger diameter, which can increase the magnetic shielding effect of the adjustment ring 84.

[0064] Preferably, an outer edge of the second radial collar portion is at least approximately aligned, viewed in the axial direction, with an origin 98 of the first rotor disk 24 facing the pump inlet 14. The origin 98 refers to that thickened portion of the rotor disk 24 which serves to mount the rotor disk 24 on the rotor 18 and from which rotor vanes 100 of the rotor disk 24 extend radially outward in a tapered manner.

[0065] As can be seen particularly from Fig. 2As can be seen, there is a rounded or beveled intermediate region 102 between the origin 98 of the rotor disk 24 and a rotor blade 100 of the rotor disk 24. If the bevel of the intermediate region 102 is conceptually continued in the direction of the pump inlet 14, the bevel can also define the outer edge of the second radial collar section of the collar 88 if the bevel and the second radial collar section are at least approximately at the same axial height. Accordingly, the outer edge of the second radial collar section delimits the collar 88 of the adjusting ring 84 in a region which is located radially between the intermediate region 102 of the rotor disk 24 and the intermediate section 57b of the locking ring 55.

[0066] Furthermore, it is also conceivable that the axial collar section 94 is not aligned parallel to the rotational axis 20 of the rotor 18, but can also extend obliquely thereto, i.e., the axial collar section 94 does not protrude orthogonally from the radial collar section 90, but rather at an angle other than 90°. Furthermore, it is also conceivable that the collar 88 of the adjusting ring 84 has a plurality of radial and axial collar sections, so that the collar 88 continues in a stepped manner in the direction of the first rotor disk 24 facing the pump inlet 14.

[0067] To further improve the protection against contamination, the radial collar section 90 and / or the axial collar section 94 of the adjusting ring 84 and / or the locking ring 55 can have structures (not shown), in particular groove-like and preferably spiral groove-like structures, which face the labyrinth-like annular gap 96 and by means of which a pumping system based on the Holweck and / or Siegbahn pumping principle is formed. Preferably, the pumping action of such a pumping system is such that the gas conveying direction is directed away from the bearing gap 52 in order to counteract an unwanted foreign body with a counterflow, so that the foreign body cannot enter the bearing gap 52 or at least the penetration of the foreign body into the bearing gap 52 is made more difficult. List of reference symbols

[0068] 10Turbomolecular pump 12Inlet flange 14Pump inlet 16Housing 17Stator 18Rotor 20Rotation axis 22Rotor shaft 24Rotor disk 26, 26a, 26bStator disk 28Spacer ring 30Rotor hub 32Holweck rotor sleeve 34Holweck rotor sleeve 36, 38Holweck stator sleeve 40Rolling bearing 42Permanent magnet bearing 43Bearing gap 44Rotor-side bearing section 46Stator-side bearing section 47Longitudinal center axis 48Magnet ring 50Magnet ring 51Spring element 52Bearing gap 53Adjusting ring 54Safety bearing 55Locking ring 56Injection nut 57aRetaining section 57bIntermediate section 57cFastening section 58Absorbent disk 59 Bore 60 Motor compartment 62 Siegbahn stage 64 Sealing gas inlet 66 Drive motor 68 Motor stator 70 Core 72 Coil 74 Permanent magnet arrangement 75a Soft magnetic return path 75b Permanent magnet 76 Motor gap 78 Balancing ring 80 Encapsulation 82 Control and power supply unit 84 Adjustment ring 86 Adjustment section 88 Collar 90 Radial collar section 92 Edge area 94 Axial collar section 96 Annular gap 98 Origin 100 Rotor blade 102 Intermediate area

Claims

1. An adjustment ring (84) comprising an adjustment section (86) for the axial alignment of a radially inwardly disposed first bearing section (46) of a bearing (42) of a vacuum pump (10), in particular a turbomolecular pump (10), in the direction of a longitudinal center axis (47) of the bearing (42) relative to a radially outwardly disposed second bearing section (44) of the bearing (42) of the vacuum pump (10), wherein a circumferential collar (88) emerges from the adjustment section (86) of the adjustment ring (84) and has a radially outwardly extending radial collar section (90), characterized in that an axial collar section (94) emerges in an angled manner from the radial collar section (90).

2. An adjustment ring (84) according to claim 1, characterized in that the axial collar section (94) emerges from the radial collar section (90) at a radially outwardly disposed edge region (92) of the radial collar section (90).

3. An adjustment ring (84) according to claim 1 or 2, characterized by at least one further radial collar section which in particular emerges from the radial collar section (90) or the axial collar section (94), and / or at least one further axial collar section which in particular emerges from the radial collar section (90) or the axial collar section (94).

4. An adjustment ring (84) according to at least one of the claims 1 to 3, characterized in that the or each radial collar section (90) has a smaller axial dimension than the adjustment section (86) and / or the or each axial collar section (94) and the adjustment section (86) have at least approximately the same axial dimensions.

5. An adjustment ring (84) according to at least one of the claims 1 to 4, characterized in that the adjustment ring (84) at least sectionally has a ferromagnetic material, in particular a soft magnetic material, and / or an electrically conductive material.

6. A bearing (42) for a vacuum pump (10), in particular a turbomolecular pump (10), comprising a radially inwardly disposed first bearing section (46), a radially outwardly disposed second bearing section (44) and an adjustment ring (84) according to at least one of the claims 1 to 5 for the axial alignment of the first bearing section (46) relative to the second bearing section (44) in the direction of a longitudinal center axis (47) of the bearing (42), characterized in that the radially extending collar section (90) spans the second bearing section (44) in the radial direction and the axial collar section (94) partly axially overlaps with the second bearing section (44).

7. A bearing (42) according to claim 6, characterized by a locking ring (55) for locking the second bearing section (44) which is at least sectionally arranged between the adjustment section (56) and the axial collar section (94), viewed in the radial direction.

8. A bearing (42) according to claim 7, characterized in that the locking ring (55) together with the adjustment ring (84) defines an annular gap (96) having a cross-section angled a multiple of times.

9. A bearing (42) according to at least one of the claims 6 to 8, characterized in that the bearing (42) is a magnetic bearing (42) and the first and second bearing section (46, 44) each comprise at least one magnet (48, 50).

10. A vacuum pump (10), in particular a turbomolecular pump (10), comprising a rotor (18) rotatably supported relative to a stator (17) and a bearing (42) according to at least one of the claims 6 to 9 for supporting the rotor (18) at the stator (17).

11. A vacuum pump (10) according to claim 10, characterized in that the stator (17) is arranged radially within the rotor (18).

12. A vacuum pump (10) according to claim 10 or 11, characterized in that the adjustment ring (84) is in threaded engagement with the stator (17).

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