EP3845764A2 - Vacuum pump and vacuum pump system - Google Patents

Abstract

The invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, with an inlet, an outlet, a housing that encloses a pump space for a gas to be pumped from the inlet to the outlet in one pumping direction, and at least one Holweck pump stage that includes at least one Holweck stator and comprises at least one Holweck rotor which rotates around an axis of rotation during operation and delimits a Holweck pump area together with the Holweck stator, the Holweck pump area having an axial length with a first axial end and a second axial end in relation to the axis of rotation, wherein at least one further inlet for gas to be pumped is provided, which leads via an inlet channel to an opening formed in the Holweck stator of the further inlet into the Holweck pumping area, the opening in the axial direction between the first axial end and the second axial end of the Holweck pumping area is located, and wherein the inlet channel at the at least one mouth section, which is formed in the Holweck stator and leads to the mouth in the Holweck pumping area.

Description

The invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, with an inlet, an outlet, a housing that encloses a pump space for a gas to be pumped from the inlet to the outlet in one pumping direction, and at least one Holweck pump stage, the at least one Holweck stator and comprises at least one Holweck rotor which rotates around an axis of rotation during operation and delimits a Holweck pump area together with the Holweck stator, the Holweck pump area having an axial length with a first axial end and a second axial end in relation to the axis of rotation, and wherein at least one further inlet is provided for gas to be pumped, which leads via an inlet channel to an opening formed in the Holweck stator of the further inlet into the Holweck pumping area.

Vacuum pumps with several inlets are known in principle and are also referred to as split-flow vacuum pumps. The terms "SplitFlow" and "SPLIT-FLOW" are registered trademarks of Pfeiffer Vacuum GmbH. Other names for such a vacuum pump are also multi-inlet vacuum pump and multi-inlet vacuum pump.

Split-flow vacuum pumps are used in particular for pumping several chambers (recipients) with different pressures, especially those arranged in series one behind the other. Typically, split-flow vacuum pumps include two to six inlets that are spaced along an axis of the pump. The split-flow vacuum pumps usually comprise a stack, that is to say a series arrangement, of pump stages connected in series within of the pump room. These pump stages typically include one or more turbo-molecular pump stages and one or more molecular pump stages, in particular one or more Holweck pump stages. In a typical application, the highest pumping speed and the lowest pressure range are available at the first inlet, ie at the inlet connected upstream of all other inlets. The downstream inlets are located in higher pressure ranges according to their sequence and deliver lower pumping speeds. However, split-flow vacuum pumps are also known in which the highest pumping speed or the highest pumping speed is available at an inlet which is arranged between two further inlets. The specific design of a respective split-flow pump depends in particular on the respective application.

As far as the mentioned Holweck pump stages are concerned, they belong - as mentioned - to the genus of molecular vacuum pumps and each generate a molecular flow by rotating a Holweck rotor relative to one or more Holweck stators. A vacuum pump can comprise one or more Holweck pump stages, wherein several Holweck pump stages can pump both in series and in parallel with one another. Typically, but not necessarily, Holweck pump stages are used in turbo-molecular vacuum pumps and are then usually connected downstream of one or more turbo-molecular pump stages in the pumping direction.

A Holweck pumping stage comprises a Holweck rotor and a Holweck stator, the Holweck rotor having a rotor shaft to which one or more Holweck sleeves (which are sometimes also referred to as rotor sleeves) are concentrically attached by means of a, for example, disk-shaped Holweck hub are. The Holweck stator has a single or multiple Holweck thread. The gas molecules to be conveyed are caused by the rotating movement of the Holweck rotor relative to the Holweck stator along the threads of promoted an inlet to an outlet. A thread turn comprises a circumferential Holweck channel (groove) which is delimited by the walls of a web and in which the gas molecules are conveyed when the rotor sleeve rotates relative to the stator. In order to minimize backflow losses, the width of the radial gap (Holweck gap) between the top of the web, i.e. the web tip, and the rotor sleeve is kept small.

In Holweck pump stages, the Holweck stator can be either radially outside or radially inside the rotor sleeve, ie both a (radially) outer and a (radially) inner stator can be connected to the corresponding side, i.e. the outside or the inside, of the rotor sleeve form a pumping active Holweck pumping area. A Holweck rotor can therefore work together with two Holweck stators at the same time, and conversely, a Holweck stator can also work together with two Holweck rotors at the same time.

So-called "folded" Holweck arrangements are also known, in which several Holweck pump stages are arranged concentrically one inside the other and are connected in series in a pumping effective manner, i.e. follow one another directly as seen in the pumping direction, so that the gas to be pumped is pumped through the successive Holweck pump areas and the pumping directions of Holweck pumping stages which are radially directly following one another are opposite to one another. Two directly successive Holweck pump stages, i.e. a (radially) outer Holweck pump stage and a (radially) inner Holweck pump stage, can comprise a common Holweck stator provided on both sides with a Holweck thread (also referred to as "double-sided"), which is located between two rotor sleeves.

In principle, it is also known to provide so-called “conical” Holweck pump stages, in which the Holweck stator is designed in such a way that the web height decreases in the pumping direction. This can be especially with a constant Bar tip diameter can be achieved in that the so-called groove base diameter increases in the pumping direction. Such Holweck pump stages can have improved pump properties.

The inlets of the split-flow vacuum pumps are often referred to as taps. If a split-flow vacuum pump is not only provided with one or more turbo-molecular pump stages - i.e. generally a turbo area - but also has one or more Holweck pump stages - generally a Holweck range - then it is generally known that such split flow -Vacuum pumps can not only have taps in the turbo area, but also in the Holweck area.

If the Holweck area has a so-called "folded" Holweck arrangement with at least two Holweck pump stages connected in series, then it is also known to provide a tap in the transition area of two directly consecutive Holweck pump stages. The advantage of such a tap is that the inlet provided for this tap, which is also referred to as the port and the opening into the transition area, can in most cases be implemented in a particularly simple manner.

It is disadvantageous that the previously known definition of the tap in the transition area of two directly successive Holweck pump stages does not open up any possibilities for variation.

The object of the invention is therefore to eliminate this disadvantage and to create a vacuum pump with several inlets and at least one Holweck pump stage, which can be adapted to different requirements.

This problem is solved in each case by the features of the independent claims.

In the vacuum pump according to the invention it is provided that the opening into the Holweck pump area is located in the axial direction between the first axial end and the second axial end of the Holweck pump area, and that the inlet channel comprises at least one opening section which is formed in the Holweck stator is and leads to the mouth in the Holweck pumping area.

According to the invention, the tap into the Holweck area does not take place at a transition between two directly successive Holweck pump stages, but at a point on the Holweck stator between the two axial ends of the Holweck pump area. As a result, on the one hand, the vacuum pump according to the invention is not dependent on the presence of a transition between two directly successive Holweck pump stages. According to the invention, a tap into the Holweck area can consequently also take place when there is only one Holweck pump stage or several Holweck pump stages that do not follow one another directly. On the other hand, the axial position of the mouth in the Holweck pumping area can in principle be chosen as desired. This has the advantage that the pressure at the tap can be selected comparatively freely as a function of this axial position of the mouth.

Surprisingly, it has been shown that if the inlet channel does not open into the Holweck pump area at a transition area between directly successive Holweck pump stages, very good pumping results can be achieved with a multiple-inlet vacuum pump.

The invention also relates to a vacuum pump system with a vacuum pump, in particular a turbo-molecular vacuum pump, of the type disclosed herein and with at least one device to be evacuated or at least one device which comprises at least one vacuum chamber to be evacuated. In particular, it is provided in this vacuum pump system that the device to several comprises evacuating vacuum chambers which are arranged one behind the other and each have a gas outlet which is in flow connection with an inlet of the vacuum pump during pumping operation.

Advantageous developments of the invention are also given in the dependent claims, the description and the drawing.

In some exemplary embodiments of the invention it can be provided that several pump stages connected in series in the pumping direction between the inlet and the outlet are provided, which include the Holweck pumping stage and at least one turbo-molecular pumping stage, which is arranged upstream of the Holweck pumping stage in the pumping direction.

The invention can thus also be implemented on multi-inlet or split-flow vacuum pumps that have different types of pump stages, in particular one or more turbo-molecular pump stages and one or more Holweck pump stages that are connected in series in the pumping direction.

Furthermore, according to some developments of the invention it can be provided that in addition to the Holweck pump stage, at least one further Holweck pump stage is provided, these at least two Holweck pump stages being arranged concentrically and successively in the pumping direction with respect to the axis of rotation forming a common axis of rotation and at least comprise two Holweck stators, one of which is arranged radially inside the other and wherein the mouth and the mouth section extending up to the mouth are formed in the radially inner Holweck stator.

With such an arrangement of Holweck pump stages, also referred to as "folded", according to the invention, the opening of the further inlet into the Holweck pumping area formed on the radially inner Holweck stator. An advantage of this embodiment is shown when the inner Holweck stator has a comparatively thick wall thickness in the radial direction, in particular in comparison to the outer Holweck stator. It has been shown that relatively large conductance values can be achieved due to this comparatively thick wall thickness.

In a typical pumping direction in connection with "folded" Holweck arrangements, the gas to be pumped is first pumped through the radially outer Holweck pump area and then - after passing the transition between the two Holweck pump stages - through the radially inner Holweck pump area. If, according to the exemplary embodiment in question, the opening of the further inlet is formed in the Holweck stator of the radially inner Holweck pumping area, then the invention can be referred to as a relocation of the tap in the downstream direction, based on the pumping direction, compared to the known tap at the transition area become.

In general, according to some exemplary embodiments of the invention, it can therefore be provided that the opening of the further inlet into the Holweck pumping area is located downstream of a transition area between two directly successive Holweck pumping stages in relation to the pumping direction.

Furthermore, according to some exemplary embodiments of the invention, it can be provided that the mouth section has at least two channel sections that do not run parallel to one another.

This results in a high degree of flexibility with regard to the course of the inlet channel within the Holweck stator provided with the mouth. According to some exemplary embodiments, it can be provided that the mouth section comprises a channel section formed in the Holweck stator, which extends from a base side of the Holweck stator. In particular, the base side of the Holweck stator is the side that faces away from a turbo-molecular pumping stage - if one is present.

This channel section formed on the Holweck stator can, according to further exemplary embodiments of the invention, extend from the base side in the axial direction parallel to the axis of rotation in the Holweck stator. Such a channel section can be produced in a particularly advantageous manner by drilling or milling.

Furthermore, according to some exemplary embodiments of the invention, it can be provided that the mouth section comprises a channel section formed in the Holweck stator, which ends at the mouth and runs in the radial direction perpendicular to the axis of rotation. Such a channel section can also be produced in a particularly advantageous manner by drilling or milling.

Furthermore, according to some exemplary embodiments, it can be provided that the inlet channel has an inlet section, which is located between the further inlet and the Holweck stator and in an adjoining the Holweck stator, which is formed in one piece with the Holweck stator or is supported by the Holweck stator. Stator is designed as a separate component of the vacuum pump. This component can in particular be a so-called lower part of the vacuum pump or an intermediate component.

According to some embodiments of the invention, the inlet section can merge directly into the mouth section of the inlet channel formed in the Holweck stator and leading to the mouth.

Such a course of the inlet channel between the further inlet and opening into the Holweck pump area can be provided in particular when the Holweck stator and another component, in particular a lower part or an intermediate component of the vacuum pump, are in direct contact with one another, such a direct contact. Concern does not exclude that one or more sealing elements are arranged between Holweck stator and component or lower part or intermediate component.

The invention is not restricted to the fact that the further inlet opens into the Holweck pump area at only one point. In some exemplary embodiments of the invention, the inlet channel can consequently, proceeding from the further inlet, lead to a plurality of openings into the Holweck pump area.

According to some exemplary embodiments of the invention, it can accordingly be provided that the inlet channel comprises a plurality of mouth sections formed in the Holweck stator, each of which leads to at least one, preferably to exactly one, of the plurality of mouths.

Here, according to some embodiments of the invention, it can be provided that the inlet channel has an inlet section which is located between the further inlet and the Holweck stator and is designed as a collecting section or comprises at least one collecting section that has a plurality of orifices, preferably with all mouths, is in flow connection.

By providing such a collecting section, it is consequently not necessary for each opening to have its own inlet channel which leads from the further inlet to the respective opening.

The collecting section can in particular be formed in a component of the vacuum pump adjoining the Holweck stator, formed in one piece with the Holweck stator or separate from the Holweck stator, i.e. in a component as has already been described elsewhere. This component for the collecting section can in turn be a so-called lower part or an intermediate component of the vacuum pump.

According to further possible embodiments of the invention, it can be provided that the Holweck stator is provided with a Holweck thread and the groove base diameter varies in the pumping direction. As already explained at the beginning, such so-called "conical" Holweck pump stages are known in principle. According to the invention it can therefore be provided that the further inlet opens into the Holweck pumping area of such a conical Holweck pumping stage.

In a preferred embodiment of the invention, this conical Holweck pump stage is part of a so-called "folded" Holweck arrangement, ie in addition to the Holweck pump stage with the mouth according to the invention, at least one further Holweck pump stage is provided, this having at least two Holweck pump stages are arranged concentrically and successively in the pumping direction with respect to the axis of rotation forming a common axis of rotation, i.e. connected in series, and comprise at least two Holweck stators, one of which is arranged radially inside the other, and wherein the mouth and the mouth section extending up to the mouth are formed in the radially inner Holweck stator. The radially outer Holweck pump stage can also be a conical Holweck pump stage. However, it is provided in particular that the groove base diameter decreases in the pumping direction.

It can be provided for the radially inner Holweck pump stage and / or for the radially outer Holweck pump stage that the web height of the Holweck thread decreases in the pumping direction.

Different configurations of Holweck pump stages with a conical configuration can consequently be combined with one another as required in a vacuum pump according to the invention. It has been found to be advantageous if the opening of the further inlet is formed on the radially inner Holweck stator, that is, the tapping into the Holweck area takes place on the radially inner Holweck pumping stage.

Fig. 1

eine perspektivische Ansicht einer Turbomolekularpumpe,

Fig. 2

eine Ansicht der Unterseite der Turbomolekularpumpe von Fig. 1,

Fig. 3

einen Querschnitt der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie A-A,

Fig. 4

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie B-B,

Fig. 5

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie C-C,

Fig. 6

ein bekannte Vakuumpumpsystem mit einer Splitflow-Vakuumpumpe, die erfindungsgemäß ausgebildet sein kann, und mit einer zu evakuierenden Einrichtung, und

Fig. 7

schematisch einen Teil einer erfindungsgemäßen Vakuumpumpe.

The invention is described below by way of example with reference to the drawing. Show it:

Fig. 1

a perspective view of a turbo molecular pump,

Fig. 2

a view of the underside of the turbo molecular pump of FIG Fig. 1 ,

Fig. 3

a cross section of the turbo molecular pump along the in Fig. 2 shown section line AA,

Fig. 4

a cross-sectional view of the turbo molecular pump along the line in FIG Fig. 2 shown section line BB,

Fig. 5

a cross-sectional view of the turbo molecular pump along the line in FIG Fig. 2 shown section line CC,

Fig. 6

a known vacuum pump system with a split-flow vacuum pump, which can be designed according to the invention, and with a device to be evacuated, and

Fig. 7

schematically part of a vacuum pump according to the invention.

In the Fig. 1 The turbo molecular pump 111 shown comprises a pump inlet 115 which is surrounded by an inlet flange 113 and to which a recipient (not shown) can be connected in a manner known per se. The gas from the recipient can be sucked out of the recipient via the pump inlet 115 and conveyed through the pump to a pump outlet 117 to which a backing pump, such as a rotary vane pump, can be connected.

In the orientation of the vacuum pump, the inlet flange 113 forms according to FIG Fig. 1 the upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121 on which an electronics housing 123 is arranged laterally. Electrical and / or electronic components of the vacuum pump 111 are accommodated in the electronics housing 123, for example for operating an electric motor 125 arranged in the vacuum pump (see also FIG Fig. 3 ). A plurality of connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, for example in accordance with the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.

There are also turbo-molecular pumps that do not have an electronic housing attached in this way, but are connected to external drive electronics.

A flood inlet 133, in particular in the form of a flood valve, is provided on the housing 119 of the turbo molecular pump 111, via which the vacuum pump 111 can be flooded. In the area of the lower part 121, a sealing gas connection 135, which is also referred to as a purging gas connection, is also arranged above which purge gas to protect the electric motor 125 (see e.g. Fig. 3 ) can be admitted into the engine compartment 137, in which the electric motor 125 in the vacuum pump 111 is accommodated, before the gas conveyed by the pump. Two coolant connections 139 are also arranged in the lower part 121, one of the coolant connections being provided as an inlet and the other coolant connection being provided as an outlet for coolant, which can be passed into the vacuum pump for cooling purposes. Other existing turbo-molecular vacuum pumps (not shown) are operated exclusively with air cooling.

The lower side 141 of the vacuum pump can serve as a standing surface, so that the vacuum pump 111 can be operated standing on the lower side 141. The vacuum pump 111 can, however, also be attached to a recipient via the inlet flange 113 and can thus be operated in a suspended manner, as it were. In addition, the vacuum pump 111 can be designed in such a way that it can also be put into operation when it is oriented in a different way than in FIG Fig. 1 is shown. Embodiments of the vacuum pump can also be implemented in which the underside 141 cannot be arranged facing downwards, but facing to the side or facing upwards. In principle, any angle is possible.

Other existing turbo-molecular vacuum pumps (not shown), which are in particular larger than the pump shown here, cannot be operated in an upright position.

At the bottom 141, which in Fig. 2 is shown, various screws 143 are also arranged by means of which components of the vacuum pump not specified here are attached to one another. For example, a bearing cap 145 is attached to the underside 141.

Fastening bores 147 are also arranged on the underside 141, via which the pump 111 can be fastened to a support surface, for example. This is not possible with other existing turbo molecular vacuum pumps (not shown), which are in particular larger than the pump shown here.

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

Like the sectional views of the Figures 3 to 5 show, the vacuum pump comprises several process gas pump stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.

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

The turbo-molecular pump 111 comprises several turbo-molecular pump stages connected in series with one another with several radial rotor disks 155 fastened to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119. A rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular one Pumping stage. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

The vacuum pump also comprises Holweck pump stages which are arranged one inside the other in the radial direction and are connected in series with one another for effective pumping. There are other turbo-molecular vacuum pumps (not shown) that do not have Holweck pump stages.

The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylinder-jacket-shaped Holweck rotor sleeves 163, 165 which are attached to the rotor hub 161 and carried by the latter, which are oriented coaxially to the axis of rotation 151 and nested in one another in the radial direction. Furthermore, two cylinder jacket-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and, viewed in the radial direction, are nested inside one another.

The active pumping surfaces of the Holweck pump stages are formed by the jacket surfaces, that is to say by the radial inner and / or outer surfaces, of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radial inner surface of the outer Holweck stator sleeve 167 lies opposite the radial outer surface of the outer Holweck rotor sleeve 163 with the formation of a radial Holweck gap 171 and with this forms the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169 with the formation of a radial Holweck gap 173 and forms with this a second Holweck pumping stage. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165 with the formation of a radial Holweck gap 175 and with this forms the third Holweck pumping stage.

At the lower end of the Holweck rotor sleeve 163, a radially running channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. In addition, a radially running channel can be provided at the upper end of the inner Holweck stator sleeve 169, via which the middle Holweck gap 173 is connected to the radially inner Holweck gap 175. As a result, the nested Holweck pump stages are connected in series with one another. At the lower end of the radially inner Holweck rotor sleeve 165 can furthermore be provided with a connection channel 179 to outlet 117.

The aforementioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves running helically around the axis of rotation 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and the gas for operating the Drive vacuum pump 111 in the Holweck grooves.

For the rotatable mounting of the rotor shaft 153, a roller bearing 181 is provided in the area of the pump outlet 117 and a permanent magnetic bearing 183 in the area of the pump inlet 115.

In the area of the roller bearing 181, a conical injection molded nut 185 is provided on the rotor shaft 153 with an outer diameter that increases towards the roller bearing 181. The injection-molded nut 185 is in sliding contact with at least one stripper of an operating medium reservoir. In other existing turbo-molecular vacuum pumps (not shown), an injection screw can be provided instead of an injection nut. Since different designs are thus possible, the term "spray tip" is also used in this context.

The operating medium reservoir comprises several absorbent disks 187 stacked on top of one another, which are impregnated with an operating medium for the roller bearing 181, e.g. with a lubricant.

During operation of the vacuum pump 111, the operating medium is transferred by capillary action from the operating medium reservoir via the scraper to the rotating injection nut 185 and, as a result of the centrifugal force, is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 to the roller bearing 181, where it eg fulfills a lubricating function. The roller bearing 181 and the operating medium store are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

The permanent magnetic bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each of which comprises a ring stack of several permanent magnetic rings 195, 197 stacked on top of one another in the axial direction. The ring magnets 195, 197 are opposite one another with the formation of a radial bearing gap 199, the rotor-side ring magnets 195 being arranged radially on the outside and the stator-side ring magnets 197 being arranged radially on the inside. The magnetic field present in the bearing gap 199 causes magnetic repulsive forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be supported radially. The rotor-side ring magnets 195 are carried by a carrier section 201 of the rotor shaft 153 which surrounds the ring magnets 195 radially on the outside. The stator-side ring magnets 197 are carried by a stator-side support section 203 which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119. The ring magnets 195 on the rotor side are fixed parallel to the axis of rotation 151 by a cover element 207 coupled to the carrier section 201. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 151 in one direction by a fastening ring 209 connected to the carrier section 203 and a fastening ring 211 connected to the carrier section 203. A plate spring 213 can also be provided between the fastening ring 211 and the ring magnet 197.

An emergency or retainer bearing 215 is provided within the magnetic bearing, which runs empty during normal operation of the vacuum pump 111 without contact and only comes into engagement with an excessive radial deflection of the rotor 149 relative to the stator to create a radial stop for the rotor 149 to form so that a collision of the rotor-side structures with the stator-side structures is prevented becomes. The backup bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and / or the stator, which has the effect that the backup bearing 215 is disengaged during normal pumping operation. The radial deflection at which the backup bearing 215 engages is dimensioned large enough that the backup bearing 215 does not come into engagement during normal operation of the vacuum pump, and at the same time small enough that a collision of the rotor-side structures with the stator-side structures under all circumstances is prevented.

The vacuum pump 111 comprises the electric motor 125 for rotatingly driving the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, the rotor shaft 153 of which extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded on the section of the rotor shaft 153 extending through the motor stator 217. Between the motor stator 217 and the section of the rotor 149 extending through the motor stator 217 there is an intermediate space 219 which comprises a radial motor gap via which the motor stator 217 and the permanent magnet arrangement for transmitting the drive torque can magnetically influence each other.

The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A sealing gas, which is also referred to as a flushing gas and which can be air or nitrogen, for example, can enter the engine compartment 137 via the sealing gas connection 135. The electric motor 125 can be protected from process gas, for example from corrosive components of the process gas, via the sealing gas. The engine compartment 137 can also be evacuated via the pump outlet 117, ie in the engine compartment 137 there is at least approximately the vacuum pressure produced by the backing pump connected to the pump outlet 117.

A so-called and known labyrinth seal 223 can also be provided between the rotor hub 161 and a wall 221 delimiting the engine compartment 137, in particular to achieve better sealing of the motor compartment 217 from the Holweck pump stages located radially outside.

The turbo-molecular vacuum pump described above and known from the prior art is not a split-flow vacuum pump. The structure and mode of operation of this turbo-molecular vacuum pump also apply in principle to the vacuum pump according to the invention.

Fig. 6 shows a possible vacuum system according to the invention with a split-flow vacuum pump 10 according to the invention and a device 12 to be evacuated by means of this vacuum pump 10.

In this exemplary embodiment, the device 12 comprises three vacuum chambers 14 arranged one behind the other, with gas entering the lowermost chamber 14 being able to pass into the respective subsequent chamber 14, as indicated by the arrows. Each chamber has a gas outlet 16 which leads to an inlet 11 or 33 of the vacuum pump 10, also referred to as a port. The inlet 33 of the vacuum pump 10, which corresponds to the gas outlet 16 of the lowermost chamber 14, is a further inlet in the sense of the invention, which - as will be described in more detail elsewhere - leads to a Holweck area of the vacuum pump 10.

The split-flow vacuum pump 10, shown here only schematically, has a housing 15 and within the housing 15 in a pump chamber 17 a rotor shaft 18 which rotates during operation and thus sets rotating components of the individual pump stages attached to it in rotation, namely by one Axis of rotation A, which is defined by the rotor shaft 18.

In the example shown here, these pump stages are turbo-molecular pump stages 47, which are followed in a pumping direction P in the pump chamber 17 by a Holweck area with two Holweck pump stages 19, 21.

From this Holweck area 19, 21 is in Fig. 6 a Holweck rotor 31 is only shown schematically, which comprises a Holweck sleeve 32 and a Holweck hub 30, via which the Holweck sleeve 32 is attached to the rotor shaft 18. This Holweck rotor 31 belongs to both Holweck pump stages 19, 21, as will be described below in connection with Fig. 7 is explained in more detail.

Gas to be pumped thus enters the pump chamber 17 of the split-flow vacuum pump 10 from the device 12 to be evacuated via its outlets 16 of the individual chambers 14 at different points via the inlets 11, 33 and is released by means of the individual pump stages 47, 19, 21 mentioned is pumped in the pumping direction P to an outlet 13, via which the gas leaves the vacuum pump 10. The basic structure explained above and its functionality is known in principle and can - as also mentioned in the introductory part - be varied in many ways, in particular with regard to the number and arrangement of the chambers 14 to be evacuated of the device 12 to be evacuated and with regard to the number, arrangement and configuration of the individual pump stages of the split-flow vacuum pump 10.

The in Fig. 7 schematically illustrated area of a split-flow vacuum pump 10 according to the invention would be in the in Fig. 6 vacuum pump 10 shown are located approximately (apart from the position of a pump lower part) at the point that is shown in Fig. 6 is indicated by a dashed square V, i.e. to the left of the in Fig. 7 Rotation axis A, not shown, at the lower end of the Holweck sleeve 32 of the Holweck rotor 31 pointing towards the outlet 13.

In Fig. 7 the housing 15, a lower part 51, an outer Holweck stator 23, an inner Holweck stator 25 and the Holweck sleeve 32 of the Holweck rotor 31 are partially shown.

The Holweck stators 23, 25 are each provided with a Holweck thread on their active pumping side facing the Holweck sleeve 32. In Fig. 7 a Holweck groove 55 is shown for each Holweck stator 23, 25, which is delimited by a web 53. These are conical Holweck stators 23, 25, in which the groove base diameter varies, the height of the webs 53 also varying and the web tip diameter and thus the radial distance between the webs 53 and the Holweck sleeve 32 being constant in the axial direction.

The Holweck sleeve 32 and the radially outer Holweck stator 23 thus form a radially outer Holweck pump area 27 and the Holweck sleeve 32 and the radially inner Holweck stator 25 form a radially inner Holweck pump area 29.

The two Holweck pump areas 27, 29 merge into one another in a transition area 43. In relation to the pumping direction P indicated by an arrow, the height of the webs 53 in the pumping direction P decreases in both Holweck pumping areas 27, 29, with the groove base diameter decreasing in the pumping direction P in the radially outer Holweck pumping stage 19, whereas in the radially inner Holweck -Pump stage 21 the groove base diameter increases in pumping direction P.

As mentioned in the introductory part, it is known in the prior art to provide a tap into the Holweck area 27, 29 at the transition area 43 via an inlet of the split-flow vacuum pump. According to the invention, however, the tap is relocated downstream in relation to the pumping direction P and thus in relation to the direction of the flow of the gas to be pumped, the tap taking place laterally in the inner Holweck stator 23.

According to the invention, an inlet channel 35 extends from a further inlet 33 of the vacuum pump to an opening 37 in the radially inner Holweck pump area 29, the opening 37 being formed in the groove 55 of the radially inner Holweck stator 25.

In the exemplary embodiment shown here, the inlet channel 35 consists of an inlet section 49 which initially runs in the radial direction and which, like the further inlet 33, is also formed in the lower pump part 51. The inlet section 49 extends in an axial direction - based on the axis of rotation A, not shown here (cf. Fig. 6 ) - extending section in the lower part 51, which is immediately followed by an axial channel section 39, which is formed in the radially inner Holweck stator 25. This axial channel section 39 merges into a radial channel section 41 of the inner Holweck stator 25, which leads to the mouth 37.

The inlet channel 35 extending from the further inlet 33 to the mouth 37 thus has an inlet section 49 formed in the lower part 51, which begins at the further inlet 33, and one formed in the radially inner Holweck stator 25 and formed by the two mentioned channel sections 39, 41 Muzzle section which ends at the mouth 37.

Since the radially inner Holweck stator 25 has a comparatively large wall thickness - measured in the radial direction - the axial duct section 39 and the radial duct section 41 can be provided with a comparatively large diameter, whereby relatively large conductance values can be achieved. The two channel sections 39, 41 can be produced by drilling or milling.

As already mentioned in the introductory part, a different axial position for the mouth 37 can also be selected depending on the respective requirement. The length of the axial channel section 39 must then be varied accordingly. The radial bore or radial milling 41 can in principle be carried out at any desired axial position in order to reach the bore which starts from the base side 45 of the radially inner Holweck stator 25 facing the lower part 51 and forms the axial channel section 39.

Furthermore, as also already mentioned in the introductory part, several channels can also open into the radially inner Holweck pumping area 29, ie several openings 37 can be provided, which differ with regard to their axial position and / or with regard to their circumferential position - each based on the Axis of rotation A (cf. Fig. 6 ) - differ from each other.

In principle, according to the invention, it is also possible to provide one or more taps in the radially outer Holweck pumping area 27, ie to form one or more openings in the radially outer Holweck stator 23 and to connect them to the further inlet 33 or via a suitable channel to be connected to another inlet for gas to be pumped.

In other pumps according to the invention, the inlet channel can be formed in another component separate from the outer Holweck stator, in particular in an intermediate component which is also referred to as an intermediate piece. Gas routing for tapping via the further inlet 33 does not therefore have to be carried out as in the exemplary embodiment in FIG Fig. 7 through the lower pump part 51, but can also be done in other ways. As mentioned elsewhere, the gas can be routed through a section of the pump which is formed in one piece with the Holweck stator.

List of reference symbols

111

Turbo molecular pump

113

Inlet flange

115

Pump inlet

117

Pump outlet

119

casing

121

Lower part

123

Electronics housing

125

Electric motor

127

Accessory connection

129

Data interface

131

Power supply connection

133

Flood inlet

135

Sealing gas connection

137

Engine compartment

139

Coolant connection

141

bottom

143

screw

145

Bearing cap

147

Mounting hole

148

Coolant line

149

rotor

151

Axis of rotation

153

Rotor shaft

155

Rotor disk

157

Stator disc

159

Spacer ring

161

Rotor hub

163

Holweck rotor sleeve

165

Holweck rotor sleeve

167

Holweck stator sleeve

169

Holweck stator sleeve

171

Holweck gap

173

Holweck gap

175

Holweck gap

179

Connection channel

181

roller bearing

183

Permanent magnet bearings

185

Injection nut

187

disc

189

commitment

191

bearing half on the rotor side

193

stator-side bearing half

195

Ring magnet

197

Ring magnet

199

Bearing gap

201

Beam section

203

Beam section

205

radial strut

207

Cover element

209

Support ring

211

Fastening ring

213

Disc spring

215

Emergency or fishing camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

10

Vacuum pump

11

inlet

12th

facility to be evacuated

13th

Outlet

14th

Vacuum chamber

15th

casing

16

Gas outlet

17th

Pump room

18th

Rotor shaft

19th

outer Holweck pumping stage

21

inner Holweck pump stage

23

outer Holweck stator

25th

inner Holweck stator

27

outer Holweck pumping area

29

inner Holweck pumping area

30th

Holweck hub

31

Holweck rotor

32

Holweck sleeve

33

further admission

35

Inlet port

37

mouth

39

axial channel section

41

radial channel section

43

Transition area

45

Base page

47

Turbo molecular pumping stage

49

Inlet section

51

Component

53

web

55

Groove

P.

Pumping direction

A.

Axis of rotation

Claims (15)

Vacuum pump, in particular turbo-molecular vacuum pump, with - an inlet (11), - an outlet (13), - A housing (15) which encloses a pump space (17) for a gas to be pumped from the inlet (11) to the outlet (13) in a pumping direction (P), and - At least one Holweck pump stage (19, 21), the at least one Holweck stator (23, 25) and at least one rotating during operation about an axis of rotation (A), together with the Holweck stator (23, 25) a Holweck Holweck rotor (31) delimiting the pump area (27, 29), wherein the Holweck pump region (27, 29) has an axial length with a first axial end and a second axial end with respect to the axis of rotation (A), and
wherein at least one further inlet (33) is provided for gas to be pumped, which via an inlet channel (35) to an opening (37) of the further inlet (33) formed in the Holweck stator (25) into the Holweck pumping area (29) leads,
characterized,
that the mouth (37) is located in the axial direction between the first axial end and the second axial end of the Holweck pump region (29), and
that the inlet channel (35) comprises at least one mouth section (39, 41) which is formed in the Holweck stator (25) and leads to the mouth (37) in the Holweck pumping area (29). Vacuum pump according to claim 1, wherein a plurality of pump stages connected one behind the other in the pumping direction (P) between the inlet (11) and the outlet (13) are provided in the pump chamber (17), which pump the Holweck pump stage (19, 21) and at least one turbo-molecular Include pump stage (47), which is arranged in the pumping direction (P) in front of the Holweck pump stage (19, 21). Vacuum pump according to claim 1 or 2, wherein in addition to the Holweck pump stage (21) at least one further Holweck pump stage (19) is provided, this at least two Holweck pump stages (19, 21) with respect to the axis of rotation (A) forming a common axis of rotation ) are arranged concentrically and successively in the pumping direction (P) and comprise at least two Holweck stators (23, 25), one of which is arranged radially inside the other, and wherein the mouth (37) and the one up to the mouth (37) extending mouth portion (39, 41) are formed in the radially inner Holweck stator (25). Vacuum pump according to one of the preceding claims, the orifice (37) being located downstream of a transition region (43) between two directly successive Holweck pump stages (19, 21) with respect to the pumping direction (P). Vacuum pump according to one of the preceding claims, wherein the mouth section has at least two channel sections (39, 41) which do not run parallel to one another. Vacuum pump according to one of the preceding claims, wherein the mouth section comprises a channel section (39) formed in the Holweck stator (25) which extends from a base side (45) of the Holweck stator (25) starts, in particular with the base side (45) facing away from a turbo-molecular pump stage (47) of the vacuum pump. Vacuum pump according to Claim 6, the channel section (39) extending from the base side (45) in the axial direction parallel to the axis of rotation (A). Vacuum pump according to one of the preceding claims, wherein the mouth section comprises a channel section (41) formed in the Holweck stator (25) which ends at the mouth (37) and runs in the radial direction perpendicular to the axis of rotation (A). Vacuum pump according to one of the preceding claims, wherein the inlet channel (35) has an inlet section (49) which is located between the further inlet (33) and the Holweck stator (25) and in one adjacent to the Holweck stator (25) , with the Holweck stator (25) formed in one piece or from the Holweck stator (25) separate component (51) of the vacuum pump, in particular wherein the component (51) is a lower part or an intermediate component, in particular an intermediate piece, of the vacuum pump . Vacuum pump according to claim 9, wherein the inlet section (49) merges directly into the mouth section (39, 41). Vacuum pump according to one of the preceding claims, wherein in the Holweck stator (25) several openings (37) into the Holweck pump area (29), each located in the axial direction between the first axial end and the second axial end of the Holweck pump area (29) ) are formed, which are based on their position in relation to the axis of rotation (A) differ from one another in the axial direction and / or in the circumferential direction. Vacuum pump according to claim 11, wherein the inlet channel (35) comprises a plurality of mouth sections (39, 41) formed in the Holweck stator (25), each of which leads to at least one, preferably exactly one, of the plurality of mouths (37). Vacuum pump according to claim 11 or 12, wherein the inlet channel (35) has an inlet section (49) which is located between the further inlet (33) and the Holweck stator (25) and is designed as a collecting section or comprises at least one collecting section, which is in flow connection with a plurality of the orifices (37), preferably with all of the orifices (37). Vacuum pump according to one of the preceding claims, wherein the Holweck stator (25) is provided with a Holweck thread and the groove base diameter varies, in particular increases, in the pumping direction (P), and / or wherein in addition to the Holweck pumping stage (21) at least one further Holweck pump stage (19) is provided, these at least two Holweck pump stages (19, 21) being arranged concentrically and in pumping direction (P) with respect to the axis of rotation (A) forming a common axis of rotation, and at least two Holweck stators (23 , 25), of which one is arranged radially inside the other, and wherein the mouth (37) and the mouth section (39, 41) extending up to the mouth (37) are formed in the radially inner Holweck stator (25) , which is provided with a Holweck thread and whose groove base diameter varies, in particular increases, in the pumping direction (P). Vacuum pump system with at least one vacuum pump (10), in particular turbo-molecular vacuum pump, according to one of the preceding claims and with at least one device (12) to be evacuated or at least one device (12) which comprises at least one vacuum chamber (14) to be evacuated, in particular wherein the device (12) comprises several vacuum chambers (14) to be evacuated, which are arranged one behind the other and each have a gas outlet (16) which is in flow connection with an inlet (11, 33) of the vacuum pump (10) during pumping operation.

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