EP3460249A1 - Split flow vacuum pump - Google Patents

Abstract

The invention relates to a split-flow vacuum pump (1) having at least two radial inlets (23-27), the vacuum pump having stator disks and rotor disks (21, 22, 24) arranged on a shaft (13). Furthermore, the shaft (13) comprises at least one sleeve (59). The sleeve (59) makes it possible to reduce the weight of the shaft (13) with constant rigidity, for example by a constriction (102) or a bore (109). The arrangement of the sleeve (59) can further change the natural vibration frequencies of the rotor and reduce the bearing forces. Furthermore, the sleeve (59) can have a bore (83) through which enclosed cavities (102, 109) can be evacuated. The sleeve (59) can also be used in the region of the motor magnet (101) or serve to connect two separate shaft elements (107, 108).

Description

The invention relates to a vacuum pump in the design of a split flow pump.

So-called split-flow vacuum pumps are used in practice to simultaneously evacuate a plurality of chambers, for example a mass spectrometer system. The split-flow vacuum pumps make it possible to dispense with a pump system consisting of several individual pumps and to carry out the evacuation of several chambers with a single pump.

Split-flow vacuum pumps have the advantage that they only have a small space requirement for the vacuum system. The split-flow vacuum pumps are not only used in analytical instruments, but also, for example, in leak detectors whose analysis principle is also based on mass spectrometry.

From the prior art ( DE 43 31 589 A1 ) a turbomolecular pump is known, which has a plurality of suction ports, which is in each case connected to one of the vacuum chambers of a device, for example a mass spectrometer. The suction ports deliver gas to various axially spaced locations of the rotor. Along the rotor axis several so-called rotor-stator packages are arranged, each compressing gas. A high vacuum side stator pack creates a pressure ratio between its inlet and outlet. The inlet is connected to a first vacuum chamber. The outlet is connected to the inlet of the next rotor-stator pack. In addition, this area is connected between two rotor-stator packages with a second vacuum chamber. Due to the pressure ratio generated by the first rotor-stator pack and the poor conductance between the vacuum chambers, the pressure in the two vacuum chambers is different. By a corresponding number of rotor-stator packets more vacuum chambers can be evacuated to different pressures, each suction port is assigned a rotor-stator package. It turns out that compared to the diameter very long rotors are difficult to handle, since the rotors are operated at speeds in the range of some 10,000 revolutions per minute.

Another variant for evacuating an arrangement with several vacuum pumps is to provide each vacuum pump with its own flange. Then this will a suitable for the pressure range vacuum pump connected. This approach is unpopular due to the high cost of the plurality of vacuum pumps. There is also a need for compact devices. However, these can not be realized with a large number of vacuum pumps.

In a variety of applications, multiple vacuum chambers are arranged in series and interconnected by low conductance holes. From one to the other end of the row decreases the pressure prevailing within the vacuum chamber gas pressure. The bores are designed so that a particle beam can pass through them and thus through the row of vacuum chambers. The vacuum chamber with the lowest pressure often contains an analyzer, such as a mass spectrometer.

From practice, split-flow vacuum pumps are known, which have three or four radial inlets and which have at least four pumping stages. Pumping stages are usually turbomolecular pumping stages. These are often combined with other pumping stages, for example Holweckpumpstufen or Gaedepumpstufen.

The length and rotor speed of the known from practice split-flow vacuum pumps is limited, inter alia, due to the natural oscillations of the rotors. A rotor can not be operated permanently in the range of a natural vibration frequency. The limiting element may on the one hand be the motor end, in which a cost due to a stiffener by larger shaft diameter, that is, larger drive magnets and motor stators, not target leader. On the other hand, the modal behavior of the rotor and in particular the rotor shaft can be critical for very long lengths.

The technical problem underlying the invention is to provide a split-flow vacuum pump in which the weight of the shaft is reduced while maintaining rigidity, in order to be able to form long split-flow vacuum pumps with long shafts. In addition, a split-flow vacuum pump is to be specified, which has a rotor shaft with at least one shaft end, which has the desired stiffening cost.

This technical problem is solved by a split-flow vacuum pump with the features according to claim 1 or by a split-flow vacuum pump with the features according to claim 10.

For longer split-flow vacuum pumps with multiple inlets, the modal behavior of the rotor, and rotor shaft in particular, can be critical. Therefore, it must be attempted to reduce the mass and thus also the weight of the shaft while maintaining rigidity, especially in the radial direction.

The invention provides a split-flow vacuum pump with at least two radial inlets, the vacuum pump having stator disks and rotor disks arranged on a shaft, wherein at least one disk package is arranged on the shaft, which is characterized in that at least one sleeve is arranged on the shaft ,

By arranging a sleeve on the shaft, the natural vibration frequencies of the rotor can be changed, so that the rotor does not have to be operated in the range of a natural vibration frequency. This also reduces the bearing forces.

In addition, it is possible to produce large rigid outer diameter without increasing the starting material of the rotor shaft, which in turn cost savings is possible.

An advantageous embodiment of the invention provides that the sleeve has a ring on at least one end. Through the ring, the sleeve can be arranged for example on a tapered shaft end. In principle, however, it is also possible to arrange the sleeve accurately on the shaft, for example, on a constant outer diameter of the shaft.

According to an advantageous embodiment of the invention, a sleeve is arranged on the shaft at least in the region of the grooves and / or holes and / or the at least one constriction. The arrangement of the sleeve in the region of the grooves and / or holes and / or the at least one constriction increases the stability of the rotor shaft. In particular, a constriction leads to a loss of rigidity of the shaft, which can be compensated by the sleeve.

A further advantageous embodiment of the invention provides that at least one sleeve is arranged on at least one shaft end in the region of a taper.

The shaft ends usually taper to be placed in bearings, such as ball bearings or magnetic bearings.

The sleeve contributes to increasing the rigidity of the shaft.

According to a preferred embodiment of the invention it is provided that the at least one sleeve is mounted on one side on the shaft and on an opposite side on at least one support ring. If, for example, the shaft has a step-shaped longitudinal section, that is to say it tapers stepwise, the sleeve can be arranged in the region of two adjacent steps. At the stage with the larger diameter, the sleeve can rest directly on the shaft. At the stage with the smaller diameter, the sleeve rests on the at least one support ring.

A particularly preferred embodiment of the invention provides that at least one magnetic ring of a magnetic bearing is arranged between a region of the shaft carrying the sleeve and the at least one support ring. This makes it possible to stiffen the shaft at the shaft end and yet to provide magnetic rings, which are arranged on the smaller diameter of the shaft and thus less expensive.

Another advantageous embodiment of the invention provides that the at least one sleeve is arranged on a region of the shaft with solid material. By this embodiment, it is possible to change the natural vibration frequency of the rotor so that the rotor is not operated in the range of natural vibration frequency.

A modified advantageous embodiment of the invention provides that the at least one sleeve is arranged in a region without a rotor shaft between shaft elements. In this case, the shaft is formed as a split shaft and the sleeve connects the shaft elements. As a result, the weight of the rotor shaft is significantly reduced, which has an advantageous effect on the modal behavior of the shaft.

A further advantageous embodiment of the invention provides that at least one bore is arranged in the sleeve. The bore is advantageously arranged in the region of the grooves and / or bores and / or constrictions. In the area of a vacuum pump, no gas-filled cavities should be present during the evacuation, since these gas-filled cavities degas during the evacuation process and thereby does not reach the actually achievable final pressure of the pump.

The at least one sleeve is advantageously made of metal. As metal, aluminum, titanium or stainless steel can be selected. The at least one sleeve may also consist of a composite material with carbon fiber, for example carbon fiber reinforced plastic. It is also possible to use a combination of the materials of metal and the composite material with carbon fibers.

Advantageously, the axial extent of the sleeve is greater than its outer diameter. According to this embodiment, the sleeve contributes optimally to improving the rigidity of the shaft.

At the motor end of the rotor, the at least one sleeve can be designed such that it is fastened in front of and behind the motor magnet on the rotor shaft. This makes it possible to design the magnetic rings with a small diameter and thus perform cost-effective. Direction high vacuum, the at least one sleeve can be applied to the rotor shaft and are connected in the direction of bearing end, for example by a ring with the shaft.

If the rotor is to be stiffened between two disk packages, a sleeve according to the invention can likewise be provided here. This sleeve can be arranged on the solid shaft. The connection between the solid shaft and the sleeve can be made for example by shrinking, pressing and / or gluing or other types of fastening.

Furthermore, it is possible to arrange the sleeve in a region of the shaft with at least one constriction or at least one recess and / or grooves and / or holes. Due to the reduced mass, which contributes little to the stiffness on the small diameter of the rotor, the natural frequency of the rotor through the sleeve can be increased. It is also positive that the support forces are reduced in this way and, for example, when using a permanent magnet bearing possibly ring magnet pairs can be saved to reduce costs.

Are rotor disks applied in the mounting direction in front of the at least one sleeve, the fit of fit of the rotor disks may be provided on a smaller outer diameter than the outer diameter of the sleeve. This is advantageous if otherwise the coil of the rotor disk, around which the rotor blades are arranged, would become too weak if the diameter of the adapter were too large, as a result of which the rotor disk would no longer be securely seated on the rotor during operation.

In addition, it is possible to produce large rigid outer diameter without having to increase the starting material of the rotor shaft, whereby a cost saving is possible.

According to a preferred embodiment of the invention, a pump structure is additionally applied to the sleeve on the outer lateral surface. Pump structures may be, for example, a turbo structure, a cross channel structure, a thread structure or a Holweck structure or a combination of these structures.

If at least one ring is arranged on the sleeve, then the at least one ring can be arranged on one side or on both sides preferably at the end of the sleeve. The ring can be fixedly arranged on the sleeve. It is also possible to form the at least one ring in one piece with the sleeve. The ring is formed as an inner ring on the sleeve.

The sleeve serves to increase the stability. In particular, in the region of a constriction, that is, a region in which the shaft has a smaller diameter than the diameter, are arranged on the rotor disks and / or rotor packages, may be provided to increase the stability of a sleeve. In the sleeve bores may be provided to degas from the sleeve covered cavities in the shaft can.

The sleeve is advantageously made of a material which has a quotient of modulus of elasticity and density which is greater than the quotient of elastic modulus and density of the shaft.

Another embodiment of the invention provides a split-flow vacuum pump having at least two radial inlets, wherein the vacuum pump has stator disks and rotor disks arranged on a shaft, wherein at least one disk package is arranged on the shaft characterized in that the shaft has an inner bore arranged along a longitudinal axis.

By this measure, the weight of the shaft is significantly reduced. Nevertheless, the rigidity remains, especially in the radial direction. This measure significantly improves the modal behavior of the rotor.

According to a further particularly preferred embodiment of the invention, it is provided that a shaft end, in which the inner bore is arranged, is cup-shaped in cross-section without inner bearing journal. By omitting the inner journal, it is possible to arrange the inner bore in said shaft end.

An advantageous development of the split flow vacuum pump according to the invention with at least three radial inlets and at least four pumping stages, wherein at least one pumping stage is designed as Turbomolekularpumpstufe, wherein the at least three inlets are designed as main inlets, which are arranged in the axial direction between the pumping stages, provides in that additionally at least one radial secondary inlet is provided which is arranged in the region of at least one turbomolecular pumping stage.

This advantageous embodiment of the vacuum pump, it is possible to provide at least one secondary inlet in addition to the main inlets. The main inlets are located between the pumping stages as known in the art. According to the advantageous embodiment, at least one further inlet is provided which is arranged in the region of at least one turbomolecular pumping stage. This means that a so-called tap, that is, the inlet is not between the turbomolecular pumping stages but that the tap leads radially into a disk pack of the at least one turbomolecular pumping stage.

This results in significantly more taps, ie inlets with a single pump on a given axial length. By the invention it is possible to evacuate as many chambers of a multi-chamber system on a short axial length.

According to an advantageous embodiment of the invention, the at least one secondary inlet has a central axis and the central axis is arranged between a first and a last slice of the at least one turbomolecular pumping stage.

This means that the secondary inlet actually leads between the disks of the disk package of the at least one turbomolecular pumping stage. As a result, in addition to the state of the art inlets located between the pumping stages, additional inlets are provided so that a larger number of vacuum chambers can be evacuated.

According to a further advantageous embodiment of the invention, it is provided that the at least one secondary inlet is arranged between two stator disks and / or between two rotor disks and / or between a stator disk and a rotor disk of at least one turbomolecular pumping stage.

This means that the secondary inlet is arranged between the disks of a stator pack, while a main inlet is arranged between the stator packs.

According to a further advantageous embodiment of the invention, the at least one secondary inlet is arranged between two adjacent stator disks and / or between adjacent rotor disks and / or between a stator disk and an adjacent rotor disk of at least one turbomolecular pumping stage. This means that the secondary inlets are chosen to be relatively small in diameter and arranged between the discs.

It is advantageously provided that a pumping speed of the at least one secondary inlet is less than the suction capacity of a main inlet.

The secondary inlets serve to increase the number of taps of a multi-chamber system to be evacuated.

Between the individual pumping stages, that is to say between the individual disk packages or other pumping stages, for example Gaede or Holweck pumping stages, there is a relatively large amount of space, so that the main inlets can have a relatively large cross section. The secondary inlets lead between disks of turbomolecular pumping stages and therefore have only a relatively small cross-section.

In accordance with a further advantageous embodiment of the invention, it is provided that n-1 secondary inlets are provided in the case of n disks.

This means that the number of secondary inlets is less than the number of slices. If a disk pack of the turbomolecular pumping stage is formed from two disks, a secondary inlet can be provided between these two disks.

However, it is also possible to provide a plurality of radial secondary inlets in the region of a turbomolecular pumping stage. Likewise, it is also possible to provide one or more secondary inlets at multiple turbomolecular pumping stages in each of these turbomolecular pumping stages. Various turbomolecular pumping stages may be formed with and without secondary inlets.

It is advantageously provided that, in addition to the at least one turbomolecular pumping stage, at least one Holweck pumping stage and / or one Siegbahn pumping stage and / or one Gaedepumpstufe and / or a Seitenkanalpumpstufe and / or a Gewindepumpstufe is provided.

Split-flow vacuum pumps usually consist of one or more turbomolecular pumping stages and at least one other of said pumping stages.

By combining different pumping stages, the pressure conditions in the chambers to be evacuated can be adjusted accordingly.

For example, it is possible to provide a main inlet between the pumping stages, for example between two turbomolecular pumping stages, and for example additionally to arrange a Holweck pumping stage. According to the invention, at least one further secondary inlet is additionally arranged in the region of the at least one turbomolecular pumping stage.

According to a further advantageous embodiment of the invention, it is provided that a turbomolecular pump stage is formed from one or more rotor disks and / or from one or more stator disks.

A pumping stage usually consists of at least one stator disk and at least one rotor disk. Often, a plurality of stator disks and a plurality of rotor disks, which engage alternately, are provided. According to the invention, it is advantageously provided that n-1 secondary inlets are provided for n disks. For example, if a stator disk and a rotor disk are provided which form a turbomolecular pump stage, the inlet is arranged between these disks.

A further advantageous embodiment of the invention provides that a stator disk and an adjacent rotor disk of a turbomolecular pumping stage define an axial length L, and that a distance between two turbomolecular pumping stages is at least as great as this length L.

As a result, it is defined that at least one stator disk and / or one rotor disk form at least one turbomolecular pumping stage. If the distance between adjacent stator disks and / or adjacent rotor disks is so great that the length L is exceeded, a new turbomolecular pumping stage commences according to the invention. An inlet in this area between the turbomolecular pumping stages is considered to be the main inlet. An inlet in the area of the turbomolecular pumping stage itself is considered as a secondary inlet.

According to a further embodiment of the invention, it is provided that a turbomolecular pump stage is formed from at least one rotor disk.

The embodiment according to the invention with regard to the inlets can in principle also be used in a turbomolecular pump.

Advantageously, a pumping stage consists of at least one rotor disk and at least one stator disk. In this case, the secondary inlet is arranged between the rotor disk and the stator disk.

Another advantageous embodiment of the split-flow vacuum pump according to the invention with at least two radial inlets, wherein the vacuum pump has stator disks and rotor disks arranged on a shaft, wherein at least two disk packages are arranged on the shaft, wherein the shaft has at least two different outer diameters and the disk packages to the Having outer diameter adapted inner diameter, provides that the shaft has in addition to a region with a largest diameter in the axial direction on both sides in each case at least two areas with smaller diameters.

The embodiment of the invention allows a large number of individual disc packs on the shaft. According to this embodiment, it is possible to arrange four or more disk packs on the rotor.

Characterized in that the shaft in addition to a region having a largest diameter in the axial direction on both sides in each case at least two regions having smaller diameters, in each case at least one disc package can be arranged in these areas. This makes it possible to use the area with the largest diameter as a stop and to arrange in the axial direction on the adjoining area with a slightly smaller diameter on both sides of the area with the largest diameter in each case at least one disc pack. On the adjoining areas with again one slightly smaller diameter can be arranged in each case at least one further disc package. The larger diameter areas each serve as a stop for the disk packs mounted on the areas of slightly smaller diameters. In the case described, two packets are respectively pushed onto the shaft from the left and from the right, so that four packages with only two diameters are arranged, which has the advantage that a great many identical parts can be used with respect to the rotor disks and the disk packages.

In the construction of a split-flow vacuum pump, it is necessary to maintain a very high accuracy during assembly. Since the Statorscheibenpakete are arranged at a distance from each other and thus the rotor disk packages are spaced from each other, it makes sense to work on the shaft with stops. The more stops are present, the less tolerances are required for the discs and the gaps between the stator and rotor discs can be made smaller.

If the stops are missing, the rotor disks have to be manufactured with sufficient precision, which means a high manufacturing outlay, or the distance between the rotor and stator disks must be selected to be large enough so that the manufacturing tolerance does not lead to a collision between the stator and rotor disks.

The at least one disk package is advantageously mounted against a stop when the stop is not formed by a sleeve.

According to a particularly preferred embodiment of the invention it is provided that the areas with the smaller diameters on both sides of the area with the largest diameter in pairs have the same diameter. This makes it possible, on the first smaller diameters on both sides of the area with the largest diameter same disc packs, that is to assemble disc packs with the same diameter. The same applies to the areas adjacent to these areas with a further reduced diameter. As a result, it is possible to mount four disc packages, which must have only two diameters from the manufacturing forth. As a result, many identical parts can be pre-assembled, which significantly reduces the manufacturing costs.

According to a further advantageous embodiment of the invention, it is provided that transitions between the regions with different diameters are designed as a stop for the disk packs. These stops ensure that the disk packages of the rotor disks are positioned exactly between the stator disks and that manufacturing tolerances of the individual disk packages do not add up over the entire length of the shaft.

According to a further advantageous embodiment of the invention it is provided that the shaft provides a pyramidal symmetrical structure. In this case, both sides of the shaft can each be equipped with the same disc packs. In principle, it is possible to execute the wave in a stepped manner. It is also possible to form the shaft at least partially conically tapered.

The different geometries, that is, the stepped and conical geometry of the shaft can also be combined.

A further advantageous embodiment of the split-flow vacuum pump according to the invention with a housing, a shaft rotatably mounted in the housing, are arranged on the rotor disks and disposed on the housing stator disks, provides that the housing has at least two housing portions which are formed thermally decoupled or between which a reduced thermal coupling is formed. With vacuum pumps, it is often desirable to heat one side of the pump to achieve a better evacuation of the recipient. The opposite side of the pump, which is in most cases the side in which the bearings are arranged should, if possible, not be heated, or this page is even cooled if possible, to achieve a trouble-free support of the shaft.

This means that one part of the vacuum pump is exposed to very high temperatures, while the opposite part of the vacuum pump has to have relatively low temperatures.

For this reason, it is provided to achieve a thermal restriction between the at least two housing areas.

According to an advantageous embodiment of the invention, it is provided that the at least two housing areas are connected by a housing section with a wall thickness reduced in relation to the wall thickness of the two housing areas.

This means that a wall area between the two housing areas has a thinner cross-section than the rest of the housing. For example, the housing has a constriction for this purpose.

According to a further advantageous embodiment of the invention it is provided that in the region of the housing portion, a reinforcement made of a material having a lower thermal conductivity than the thermal conductivity of the housing is arranged. In particular, in a region with a constriction, such a reinforcement can be arranged advantageously.

A further advantageous embodiment of the invention provides that the at least two housing regions are formed from two separate housing components and that at least one thermal seal is arranged between the housing components. The seal advantageously has a lower thermal conductivity than the housing. Advantageously, the seal may be formed of glass and / or ceramic and / or plastic. This seal ensures that there is no heat transfer from the heated part of the housing to the cooled part of the housing.

It is advantageously provided that in the housing at least one bore and / or at least one groove is arranged, in which heating elements and / or coils for heating the housing and / or cooling elements are arranged. Through these devices, it is possible to heat the areas of the housing, which are to have a correspondingly high temperature, and to cool the areas of the housing, which are to be cooled.

According to a further advantageous embodiment of the invention, a vacuum system with at least one vacuum pump and at least one recipient is provided, in which a releasable connection is provided between the vacuum pump and the recipient, wherein for sealing the connection at least one elastomeric seal toward the atmosphere side and at least one gap seal in the direction of the vacuum side, wherein at least one suction channel and / or at least one suction opening are provided between the elastomeric seal and the gap seal.

This embodiment has the advantage that an elastomeric seal is used at the sealing points on the atmosphere side. This is advantageously designed as an O-ring. At least one gap seal is used as the second sealing element between the elastomer seal and the, for example, ultra-high vacuum connection. The surfaces of the recipient (chamber) and a surface of the pump housing are pressed against each other.

The vacuum pump according to the invention can have grooves and / or bores and / or constrictions in the rotor shaft. At least one sleeve may be arranged on at least one end of the rotor shaft. It is also possible to arrange at least one sleeve in front of or between the rotor disk packages and / or the rotor disks. The at least one sleeve can be arranged in the region of solid material of the rotor shaft. The at least one sleeve may be formed covering at least one constriction and / or the grooves and / or the holes. The sleeve can also be arranged in a rotor shaft-free area. In this case, the rotor shaft is formed as a split shaft and the at least one sleeve supports and covers the rotor shaft free area. The shaft may also be formed as a shaft with an internal bore along the longitudinal axis of the shaft. These embodiments can be used individually or in any combination in a split-flow vacuum pump.

Fig. 1

einen Längsschnitt durch eine Anordnung mit einer nicht von der Erfindung umfassten Vakuumpumpe;

Fig. 2

einen Rotor mit Hülse am Wellenende im Längsschnitt;

Fig. 3

eine Einzelheit der Fig. 2;

Fig. 4

einen Rotor mit Hülse zwischen Scheibenpaketen im Längsschnitt;

Fig. 5

einen Rotor mit Hülse zwischen Scheibenpaketen gemäß einem geänderten Ausführungsbeispiel im Längsschnitt;

Fig. 6

einen Rotor mit Einschnürung im Längsschnitt;

Fig. 7

einen Rotor mit Hülse zwischen Scheibenpaketen und geteilter Rotorwelle im Längsschnitt;

Fig. 8

einen Querschnitt durch eine Rotorwelle;

Fig. 9

einen Längsschnitt durch ein geändertes Ausführungsbeispiel einer Welle.

Fig. 10

ein Wellenende eines Rotors mit Innenbohrung im Längsschnitt;

Fig. 11

eine schematische Darstellung eines Rotors mit Scheibenpaketen mit Haupt- und Nebeneinlässen;

Fig. 12

eine Splitflow-Vakuumpumpe im Längsschnitt;

Fig. 13

eine Prinzipskizze eines Rotors mit auf dem Rotor angeordneten Rotorscheiben;

Fig. 14

einen Längsschnitt durch eine Welle mit aufgepressten Rotorscheiben;

Fig. 15

eine Prinzipskizze eines Rotors einer Splitflow-Vakuumpumpe gemäß dem Stand der Technik;

Fig. 16

ein geändertes Ausführungsbeispiel;

Fig. 17

eine Vakuumpumpe in perspektivischer Ansicht mit Vakuumanschluss;

Fig. 18

eine Hülse mit pumpaktiven Strukturen im Querschnitt;

Fig. 19

ein geändertes Ausführungsbeispiel einer Hülse mit pumpaktiven Strukturen im Querschnitt.

Further features and advantages of the invention will become apparent from the accompanying drawings, in which several embodiments of a vacuum pump according to the invention are shown by way of example only. In the drawing show:

Fig. 1

a longitudinal section through an arrangement with a not included in the invention vacuum pump;

Fig. 2

a rotor with sleeve at the shaft end in longitudinal section;

Fig. 3

a detail of Fig. 2 ;

Fig. 4

a rotor with sleeve between disk packages in longitudinal section;

Fig. 5

a rotor with sleeve between disc packages according to a modified embodiment in longitudinal section;

Fig. 6

a rotor with constriction in longitudinal section;

Fig. 7

a rotor with sleeve between disk packages and split rotor shaft in longitudinal section;

Fig. 8

a cross section through a rotor shaft;

Fig. 9

a longitudinal section through a modified embodiment of a shaft.

Fig. 10

a shaft end of a rotor with an internal bore in longitudinal section;

Fig. 11

a schematic representation of a rotor with disk packages with main and secondary inlets;

Fig. 12

a split-flow vacuum pump in longitudinal section;

Fig. 13

a schematic diagram of a rotor with arranged on the rotor rotor discs;

Fig. 14

a longitudinal section through a shaft with pressed-rotor discs;

Fig. 15

a schematic diagram of a rotor of a split-flow vacuum pump according to the prior art;

Fig. 16

a modified embodiment;

Fig. 17

a vacuum pump in perspective view with vacuum connection;

Fig. 18

a sleeve with pump-active structures in cross section;

Fig. 19

a modified embodiment of a sleeve with pump-active structures in cross section.

Fig. 1 shows a vacuum pump 1, which is designed as a so-called split-flow vacuum pump. The vacuum pump 1 is connected to a multi-chamber vacuum system 2. The multi-vacuum system 2 has four chambers 3, 4, 5, 6, the to be evacuated from the vacuum pump 1. The gas pressure in the chambers 3, 4, 5, 6 is increasing in this order. The chambers 3, 4, 5, 6 are separated by partitions 7, 8, 9, wherein holes 9, 10, 11 establish a connection. These bores 9, 10, 11 are, for example, arranged and dimensioned such that a particle beam can pass through all the chambers 3, 4, 5, 6. In particular, the first partition 7 separates the first chamber 3 and the second chamber 4, while the second partition 8 separates the second chamber 4 from the third chamber 5 and the third partition 9 separates the third chamber 5 from the fourth chamber 6. The dashed arrows in the Fig. 1 illustrate the gas flow.

The vacuum pump 1 has a shaft 13 which carries rotor disks 14 to 19. The rotor disks 14 to 19 are in engagement with stator disks 20. The rotor disks 14, 15, 16 form a first disk package 21 and the rotor disks 17 to 19 form a second disk package 22. The disk package 22 forms a high-vacuum-side rotor stator package with the stators 20. The disk package 21 forms with the stator 20 a Zwischenvakuumseitiges rotor stator. The blades in both packages are, as known in the art, both stator and rotor side attached to support rings or integrally formed with this. A first gas inlet 23 is located in front of the high-vacuum-side rotor stator packet, and a second gas inlet 24 is located in front of the forward-vacuum-side rotor stator packet.

From the multi-chamber vacuum system, a first main inlet 23 leads into the vacuum pump 1. From the second chamber 4, a second main inlet 24 leads into the vacuum pump 1. From the vacuum chamber 5, another main inlet 25 leads the vacuum pump 1 and the vacuum chamber 6, another main inlet 26 leads into the vacuum pump. 1

The main inlets 23, 24, 25, 26 are arranged between the turbomolecular pumping stages 21, 22.

In the region of the turbomolecular pumping stage 22, a first secondary inlet is arranged which leads from the vacuum chamber 5 into the vacuum pump 1. In addition, a further secondary inlet 28 leads from the vacuum chamber 6 in the region of the turbomolecular pumping stage 21 into the vacuum pump 1.

Thus, the number of inlets through the secondary inlets 27, 28 is increased. The secondary inlets 27, 28 are arranged in the region of the turbomolecular pumping stages 21, 22.

The rotor shaft 13 has areas with different diameters.

A first region 29 is a region with the largest diameter. On both sides of the shaft 13, two areas 30, 31 with smaller diameters join. This is in turn followed by regions 32, 33 with an even smaller diameter of the shaft 13. In the region 29 of the largest diameter of the shaft 13, no rotor disks are arranged. In the area 30, the rotor disk 16 is arranged, which is determined by a stop 34, which formed by the step-shaped shoulder between the region 29 and the region 30, locally unique.

The same applies to the rotor disk 15, which is determined by a stop 35 between the areas 30, 32.

The same applies to the rotor disk 17 which is fixed by a stop 36 on the shaft 13 and the rotor disk 18, which is fixed by a stop 37 on the shaft 13. Between the rotor disks 14, 15 and the rotor disks 18, 19, a spacer sleeve 38 is arranged in each case. By means of the stops 34 to 37, the rotor disks 14 to 19 are exactly placed on the shaft 13, so that narrow gaps can be formed between the rotor disks 14 to 19 and the stator disks 20.

Another advantage of the invention is that the rotor disks 14 to 19 are placed exactly on the shaft, whereby very small gaps can be formed. This increases the pumping power of the vacuum pump 1. By using many identical parts, the pump is inexpensive to manufacture. In the present embodiment, in each case two rotor disk packs each having the same inner diameter are arranged on the two sides of the region 29 of the shaft 13 with the largest diameter.

A further advantageous embodiment of the invention is an embodiment in which in the region of the largest diameter 29 grooves 39, 40 are arranged, which reduce the mass of the shaft. Since the split-flow vacuum pumps have a very long length, the modal behavior of the rotor and in particular of the rotor shaft is critical. For this reason, according to the invention, the mass and thus the weight of the shaft is reduced while maintaining rigidity.

The vacuum pump 1 has a housing 41. In order to reduce thermal transitions between the high-vacuum side and the fore-vacuum side in the housing 41, the housing 41 has a constriction 42. This constriction reduces the thermal conductivity. It is possible, in the region of the constriction 42 in addition to a not shown Provide reinforcement. The housing may also be designed to be divided in the region of the constriction 42, and a thermal seal may be arranged between the two parts of the housing.

The shaft 13 is supported by a magnetic bearing 43 on one side. In a holder 43 a only schematically shown abutment 43 b are arranged. On the other side, the bearing is not shown. For example, during storage on the side not shown, it may be an oil-lubricated ball bearing.

In Fig. 1 only turbomolecular pumping stages 21, 22 are shown.

It is also possible, in addition to the turbomolecular pumping stages, to provide a Holweck pumping stage and / or a Siegbahn pumping stage and / or a Gaedepump stage and / or a side channel pumping stage and / or a threaded pumping stage.

The rotor disk 15 and the stator disk 20 have an axial length L as viewed in the axial direction. The distance between the turbomolecular pump stages 21, 22 is greater than the length L.

Fig. 2 and in Fig. 3 show a rotor shaft 13 on which rotor disk packages 21, 22, 44 are arranged. The rotor shaft 13 is stepped, so that the rotor disk packs 21, 22, 44 respectively abut against a step and are thus accurately positioned.

At one end 104 of the rotor shaft 13, a sleeve 59 is arranged, which is supported with one end 105 on the shaft 13 and with its other end 106 on a support ring 103. The support ring 103 is in turn supported on the rotor shaft 13.

The sleeve is thus mounted in front of and behind a motor magnet 101 on the rotor shaft 13. By the sleeve 59, the rigidity of the rotor, in particular at the strongly tapered end 104 is significantly increased. At the same time, the motor magnets 101, that is, the magnetic rings can be made with the usual, relatively small diameter, which has a cost effect. Would the shaft 13 is improved by a shaft end 104 of larger diameter in terms of stiffness, the motor magnets would also have to be built larger, which would adversely affect the cost.

Fig. 4 shows a modified embodiment. According to Fig. 4 the rotor shaft 13 is stiffened by a sleeve 59 between the disk packs 21, 22. The sleeve 59 is arranged on the solid shaft 13. It may be secured to the shaft 13 by shrinking, pressing or gluing. The sleeve 59 fills the gap between the disc packs 21, 22 completely or almost completely. If it completely fills the distance between the disk packs 21, 22, it simultaneously performs the function of a spacer sleeve like the sleeves 38 in FIG Fig. 1 ,

Fig. 5 shows a modified embodiment in which the sleeve 59 is disposed on the rotor shaft 13 between the disk packs 21, 22. The sleeve 59 is arranged at a distance from the disk pack 21. The sleeve 59 is mounted on the shaft 13 of solid material and stiffened the rotor shaft thirteenth

Fig. 6 shows the rotor shaft 13 having a constriction 102. In the region of the constriction 102 is the sleeve 59 arranged. The sleeve 59 has bores 83, through which the constriction 102 can be degassed. If a recipient is evacuated by the vacuum pump, cavities in the area of the vacuum pump, such as constriction 102, must be evacuated at the same time, otherwise the cavities 102 degas during the evacuation process and thus the final pressure of the vacuum pump can not be achieved.

Fig. 7 shows the rotor shaft 13, which is formed as a divided rotor shaft with shaft elements 107, 108. The shaft members 107, 108 are interconnected by the sleeve 59. By this embodiment, the natural vibration frequencies of the rotor are changed so that a durable and reliable operation is possible. The sleeve 59 in turn has bores 83, through which a cavity 109 between the shaft elements 107, 108 can be evacuated.

In the Fig. 2 to 7 the same parts are provided with the same reference numerals.

Fig. 8 shows various ways in which the grooves 39, 40 may be formed.

In Fig. 8 13 different embodiments of grooves are shown in the shaft. The grooves can be arranged with the same cross sections rotationally symmetrical in the shaft 13. In the Fig. 8 Illustrated embodiments are exemplary only. In practice, an embodiment is selected and arranged rotationally symmetrical in the shaft.

In Fig. 8 a groove 53 is shown which has a rectangular cross-section. A groove 54 is according to a second embodiment in the direction of the central axis M is tapered conically.

Holes 55 are formed such that they form through holes 13 in the shaft. The holes 55 converge at a point 56. A groove 57 has a stepped cross-section. A groove 58 is formed widening conically in the direction of the central axis. This embodiment has the advantage that the shaft 13 retains a high rigidity. The material at the outer radius of the shaft 13 contributes more to the modal rigidity than the material at the inner radius. For this reason, the groove 58 is a particularly advantageous embodiment.

In addition to the grooves, a sleeve 59 may be provided. The sleeve 59 should be formed of a rigid material but have a low mass.

The sleeve 59 advantageously has bores 83 in the region of the grooves. These holes serve to allow the grooves 53, 54, 57, 58 and / or bores 55 to be evacuated so that they do not degas during the evacuation of the recipient.

Fig. 9 shows the shaft 13 with grooves 39, 40. The grooves 39, 40 are arranged in the axial direction at a height, that is, they form a ring in the shaft 13. In addition, in a further area in which no rotor disks 14th , 15, further grooves 63, 64 are provided, which are also arranged in the axial direction corresponding to each other and form a second ring of grooves. In addition, two sleeves 59 which cover the grooves 39, 40, 63, 64. The sleeves 59 have holes 83 in order to evacuate the grooves 39, 40, 63, 64 can.

Fig. 10 shows a shaft end 110 of the rotor shaft 13. The shaft 13 is supported by a magnetic bearing 111. The magnetic rings 112 of the magnetic bearing 111 are arranged on the shaft 13. Magnetic rings 113 of the magnetic bearing 111 are arranged on a housing 114.

In addition, a ball bearing 114 is provided, which is designed as an emergency. The ball bearing 114 is biased by a spring 115. In the shaft 13, an inner bore 116 is arranged. As a result, the weight of the shaft is significantly reduced, so that the modal behavior of the rotor is changed.

Fig. 11 shows the shaft 13 with rotor disk packages 44, 45, 46 which form turbomolecular pumping stages 44, 45, 46 with stator disk packages (not shown). The gas flow is shown by an arrow 47.

Arrows 48 represent the gas flow which is supplied from two main inlets 24, 25 to the turbomolecular pumping stages 45, 46. The arrows 49 indicate the gas flow which is supplied from two secondary inlets 27, 28 in the region of the turbomolecular pumping stages 44, 45 to the pumping system.

The secondary inlets 27, 28 are arranged in the region of the turbomolecular pumping stages 44, 45, while the main inlets 24, 25 have their supply between the turbomolecular pumping stages 44, 45 and 46.

Fig. 12 shows vacuum pump 1 with the once again clarified, the turbomolecular pumping stages 44, 45, 46, 49 has. The turbomolecular pump stages 44, 45, 46, 49 consist of rotor disks and stator disks, which are arranged intermeshing. In addition, main inlets 23, 24, 25, 26, which are arranged in front of the pumping stage 44 or between the pumping stages 44, 45, 46, 49.

The shaft 13 is supported by means of a magnetic bearing 43 and a ball bearing 50. The ball bearing 50 is an oil lubricated ball bearing. The shaft 13 is driven by a motor 51.

In the area of the turbomolecular pumping stage 44, a secondary inlet 27 is provided. A secondary inlet 28 is provided in the region of the turbomolecular pumping stage 45, and a secondary inlet 52 is provided in the region of the turbomolecular pumping stage 46.

By this embodiment, the number of inlets from the four main inlets 23, 24, 25, 26 to a total of seven inlets, namely plus the three side inlets 27, 28, 52 increases.

Fig. 13 shows a partial section through the shaft 13. The shaft 13 has the in Fig. 1 shown areas 29 having the largest diameter, the adjoining areas 30, 31 with a smaller diameter and in turn adjoining areas 32, 33 with a further reduced diameter. In the areas 30, 31, the rotor disks 16, 17 are arranged. In the areas 32, 33, the rotor disks 15, 18, 19 are arranged. The rotor disks 15, 18, 19 all have the same inner diameter. The rotor disks 16, 17 also have the same inner diameter. This makes it possible to build a low-cost pump by a large number of identical parts.

The difference in diameter between the areas 29, 30 forms the stop 34. Between the areas 29, 31 of the stopper 36 is provided. Between the areas 30, 32 of the stop 35 is arranged and between the areas 31, 33 of the stop 37 is provided.

The mounting direction of the discs 15, 16 is indicated by the arrow A. The mounting direction of the rotor disks 17, 18, 19 is indicated by the arrow B. M denotes a central axis of the shaft 13. The shaft 13 and the rotor disks 15, 16, 17, 18, 19 are constructed rotationally symmetrically about the center axis M.

Fig. 14 shows the shaft 13 with turbomolecular pumping stages 21, 22. The shaft 13 has grooves 39, 40 in a region in which no rotor disks 14, 15, 16, 17, 18, 19 are arranged.

The formation of a groove having a greater extent in the axial direction than in the circumferential direction of the shaft 13, the mass of the shaft is reduced, so that the modal behavior of the rotor significantly improved.

Fig. 15 shows a shaft 13 with two turbomolecular pumping stages 21, 22, which are arranged in a housing 41 of a split flow pump. The housing 41 has an inlet 24.

This prior art embodiment shows that a customer housing 60 has an inlet 61 formed radially offset from the inlet 24. The axial length of the pump and the customer chamber 60 do not match.

According to Fig. 16 a solution is shown how nevertheless the highest possible conductance can be achieved. For this purpose, the housing 41 has a web 62 in the region of the inlet 24. Due to the design of the web on which the stator disks (not shown) can be attached, one obtains a larger cross section and thus a higher conductance in the region of the inlet 24.

Fig. 17 shows a vacuum pump 1 with vacuum ports 72, 73, 75. The vacuum port 72 has an elastomeric seal 76 and a gap seal 77 on. Between the elastomeric seal 76 and the gap seal 77, a suction channel 78 is arranged, are arranged in the Zwischenabsaugungen 79. In the vacuum port 75, a suction opening 80 is arranged. The Zwischenabsaugungen 79 lead into a feedthrough bore 81, which is guided to the intermediate stage 73. For a seal arrangement of the vacuum connection 75, a connection channel 82 is provided, so that the vacuum connection 75 is also evacuated via the suction opening 80 via the feed-through bore 82.

Fig. 18 shows the sleeve 59, which has a carrier 117 which is formed as a substantially cylinder jacket-shaped base portion. On the radial outer side of the carrier 14, a structuring with a plurality of structural elements 118 is provided, which are formed in the present illustrative embodiment as in the direction of the longitudinal axis of the sleeve 59 elongated straight webs. The structural elements 118 may be designed as Holweck or Kreuzkanalpumpstufe. The structural elements 118 may also have other pumping stage structures.

Fig. 19 shows the shaft 13, on which the sleeve 59 is arranged. The sleeve 59 carries a turbomolecular pumping structure, which consists of discs 119, 120. Adjacent to the sleeve 59, the rotor disk 14 is provided.

Stator disks 121, 122, 123 engage in the turbomolecular pumping structure of the sleeve 59, formed by the disks 119, 120.

The discs 14, 119 to 120 are shown only schematically.

reference numerals

1

vacuum pump

2

Multi-chamber vacuum pump system

3

chamber

4

chamber

5

chamber

6

chamber

7

partitions

8th

partitions

9

partitions

10

drilling

11

drilling

12

drilling

13

wave

14

rotor discs

15

rotor discs

16

rotor discs

17

rotor discs

18

rotor discs

19

rotor discs

20

stator

21

Turbomolecular pumping stage with disc package

22

Turbomolecular pumping stage with disc package

23

main inlet

24

main inlet

25

main inlet

26

main inlet

27

Besides inlet

28

Besides inlet

29

Area of the shaft 13 with the largest diameter

30

Area of the shaft 13 with a smaller diameter

31

Area of the shaft 13 with a smaller diameter

32

Area of the shaft 13 with the smallest diameter

33

Area of the shaft 13 with the smallest diameter

34

attack

35

attack

36

attack

37

attack

38

shell

39

groove

40

groove

41

casing

42

constriction

43

magnetic bearings

43a

holder

43b

thrust bearing

44

Turbomolecular pump stage with rotor disk packages

45

Turbomolecular pump stage with rotor disk packages

46

Turbomolecular pump stage with rotor disk packages

47

Arrow gas flow

48

Arrow gas flow

49

Turbo molecular pump stage

50

ball-bearing

51

engine

52

Besides inlet

53

groove

54

groove

55

drilling

56

intersection

57

groove

58

groove

59

shell

60

casing

61

inlet

62

web

72

vacuum connections

73

vacuum connections

75

vacuum connections

76

elastomer seal

77

gap seals

78

suction

79

Zwischenabsaugungen

80

suction

81

By guide bore

82

connection

83

drilling

101

motor magnet

102

Constriction shaft

103

ring

104

End rotor shaft 13

105

End sleeve 59

106

End sleeve 59

107

shaft member

108

shaft member

109

cavity

110

shaft end

111

magnetic bearings

112

magnetic rings

113

magnetic rings

114

ball-bearing

115

feather

116

internal bore

117

carrier

118

structural elements

119

rotor disc

120

rotor disc

121

stator

122

stator

123

stator

A

arrow

B

arrow

L

axial length

M

central axis

Claims (11)

Split-flow vacuum pump with at least two radial inlets, the vacuum pump having stator disks and rotor disks arranged on a shaft, wherein at least one disk package is arranged on the shaft, characterized in that at least one sleeve (59) is arranged on the shaft (13). Vacuum pump according to claim 1, characterized in that the sleeve (59) has a ring (103) at at least one end (106). Vacuum pump according to one of the preceding claims, characterized in that on the shaft (13) at least in the region of the grooves (39, 40, 53, 54, 57, 58, 63, 64) and / or holes and / or the at least one constriction a sleeve (59) is arranged. Vacuum pump according to one of claims 1 to 3, characterized in that at least one sleeve (59) is arranged on at least one shaft end (104) in the region of a taper. Vacuum pump according to claim 4, characterized in that the at least one sleeve (59) is mounted on one side (105) on the shaft (13) and on an opposite side (106) on at least one support ring (103). Vacuum pump according to claim 5, characterized in that between a sleeve (59) carrying the region of the shaft (13) and the at least one support ring (103) at least a magnetic ring (101) of a magnetic bearing is arranged. Vacuum pump according to one of the preceding claims, characterized in that the at least one sleeve (59) is arranged on a region of the shaft (13) with solid material. Vacuum pump according to one of the preceding claims, characterized in that the at least one sleeve (59) is arranged in a region without rotor shaft between two shaft elements (107, 108). Vacuum pump according to one of the preceding claims, characterized in that in the sleeve (59) at least one bore (83) is arranged. Split-flow vacuum pump with at least two radial inlets, the vacuum pump having stator disks and rotor disks arranged on a shaft, wherein at least one disk package is arranged on the shaft, characterized in that the shaft (13) has an inner bore (116) arranged along a longitudinal axis , Vacuum pump according to claim 10, characterized in that a shaft end (110), in which the inner bore (116) is arranged, is cup-shaped in cross-section without inner bearing pin.

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