EP3693610A1 - Molecular vacuum pump - Google Patents

Abstract

The invention relates to a molecular vacuum pump with at least one molecular pumping stage, by means of which a gas can be conveyed from an inlet to an outlet of the molecular vacuum pump, the pumping stage having a pumping direction and a passage cross-section transverse to the pumping direction; and an intermediate connection which is arranged downstream within the pumping stage or the pumping stage, with an, in particular static, blocking element being arranged upstream of the intermediate connection in the pumping direction, by means of which the passage cross section is locally reduced.

Description

The present invention relates to a molecular vacuum pump with at least one molecular pumping stage, by means of which a gas can be conveyed from an inlet to an outlet of the molecular vacuum pump, the pumping stage having a pumping direction and a passage cross-section transverse to the pumping direction; and with an intermediate connection which is arranged downstream within the pump stage or the pump stage.

A flow cross section is the open area within a pumping stage in cross section measured at a selected point along the pumping direction. The passage cross-section is thus in particular formed by the sum of the openings in the relevant cross-section through which the gas particles to be conveyed can pass. In the case of a rotor-operated molecular vacuum pump, the passage cross section relates in particular to a cross section at a selected point along the rotor axis, the cutting plane running in particular perpendicular to the rotor axis.

It is an object of the invention in such a vacuum pump to improve the pumping off of gas present at the intermediate connection and / or to reduce a backflow of gas starting from the intermediate connection counter to the pumping direction.

This object is achieved by a molecular vacuum pump with the features according to claim 1, and in particular in that a preferably static blocking element is arranged in front of the intermediate connection in the pumping direction, by means of which the passage cross section is locally reduced.

The blocking element reduces, in a structurally simple manner, a backflow of gas starting from the intermediate connection counter to the pumping direction or into an area upstream of the intermediate connection in the pumping direction, and the pumping action for the gas at the intermediate connection is improved. In particular, it proves to be advantageous if the blocking element is a static element and / or is arranged on a stator of the pump, since, in particular, due to dynamic forces on the rotor, its structural change would generally be significantly more complex. The invention can thus be implemented by modifying an existing pump without having to change its rotor. In principle, however, a blocking element can also be arranged on the rotor, for example.

The blocking element is arranged in particular directly in front of the intermediate connection. Thus, the blocking element can have an advantageous conduction effect and / or screen effect for the gas or for the particles and / or give the particles a preferred direction which runs with at least one component in the pumping direction. In general, the blocking element can form, for example, a guide and / or diaphragm element.

The passage cross-section of the pump stage is defined in particular by one or more stator elements, in the case of a turbo-molecular pump stage in particular stator disks, namely in particular one or more stator elements which are arranged upstream of the blocking element in the pumping direction. The pump stage can basically have a variable passage cross section along its axial extent. The local reduction before the intermediate connection is decisive.

The local reduction or downsizing of the passage cross section is designed in particular in such a way that the compression of the pumping stage before the intermediate connection is locally increased. The pumping speed can be reduced locally in this area. At least for certain applications, however, this is justifiable in view of the improved pumping effect for the gas present at the intermediate connection. In general, the invention is particularly suitable for compression-critical applications which in particular do not require a particularly high pumping speed at the main inlet, such as, for example, in a leak detector.

According to the invention, the passage cross section is merely reduced by the blocking element, but not completely blocked. The blocking element can therefore cover part of the passage cross section, for example. It is therefore still possible to convey gas through the pumping stage past the blocking element and to the next pumping stage. The reduced passage cross-section thus in particular connects the pump stage with the axial region of the intermediate connection and / or with a further pump stage which is arranged downstream of the intermediate connection and / or the pump stage, in particular in series connection.

In general, the intermediate connection can be arranged, for example, in particular axially, within the pump stage between a first section of the pump stage and a second section of the pump stage arranged downstream. Alternatively, the intermediate connection can e.g. be arranged downstream of the pumping stage, in particular axially, and upstream of a second pumping stage, in particular axially, downstream in series. The pump stages or sections of pump stages can therefore generally be connected in series in particular. The pump stages or sections have, in particular, rotors or rotor sections which are arranged on a common rotor shaft.

The passage cross section is formed in particular by the open area of a cross section through a rotor of the pump in the area of the pumping stage. In the case of a turbomolecular pump or pump stage, a passage cross section of a turbostator disk is, for example, radially outward through a radially outer one Limitation of the turbostator blades limited. Inwardly, the passage cross section is limited by a radially inner limitation of the turbostator blades, namely by a so-called blade base. The passage cross-section has open sections separated by the blades in the circumferential direction. The same applies to a turbo rotor or a turbo rotor disk. In the case of a Holweck pump, the passage cross-section is limited to the outside or to the inside by a respective base of several Holweck grooves. In the opposite direction, i.e. inwards or outwards, the passage cross-section is limited by a Holweck rotor. The passage cross-section has open sections separated by webs in the circumferential direction, the webs separating the Holweck grooves. In general, the passage cross-section in a Holweck pumping stage corresponds in particular essentially to the sum of the cross-sections of the Holweck grooves.

In particular, the passage cross-section through the blocking element can be reduced by at least 20%, in particular at least 30%, in particular based on the cross-sectional area of the passage cross-section of the pump stage before and / or after the intermediate connection, in the case of a turbo-molecular pump, in particular an upstream stator disk.

An intermediate connection of a multistage molecular pump is also referred to, for example, as an “interstage port” and a molecular pump with such an intermediate connection is also referred to as a “split-flow vacuum pump”.

In particular, the passage cross-section through the blocking element can be locally asymmetrical, in particular with respect to a rotor axis of the pump stage. For example, the blocking element can be arranged such that on a side of a rotor shaft of the pump stage facing the intermediate connection the blocking element blocks a larger proportion of the passage cross section than on a side of the rotor facing away from the intermediate connection. Generally preferred the blocking element can be arranged on a side of the rotor shaft facing the intermediate connection. For example, the blocking element can only be arranged in a partial angular region with respect to the rotor axis, which is in particular assigned to the intermediate connection. The blocking element can block the passage cross-section in particular in an area that lies radially between the rotor axis and the intermediate connection. In general, the arrangement of the blocking element at the intermediate connection causes, in addition to a reduced return flow from the intermediate connection, also a reduction in the probability that gas molecules will escape from the upstream pump stage through the intermediate connection.

For example, it can be provided that the blocking element is made impermeable at least in a peripheral section assigned to the intermediate connection, in particular essentially only in this peripheral section. A region radially opposite the intermediate connection can in particular be free of the blocking element or the passage cross section can be open here. In the area radially opposite the intermediate connection, the stator can in particular be designed to be permeable and generally like a “normal” stator. Generally preferred, the blocking element can extend over a circumferential area which corresponds at least to the angular area of the intermediate connection and / or at most 180 °. In this circumferential section, the passage cross section can be completely or, in particular radially, partially blocked by the blocking element.

The geometry of the blocking element can, for example, be changeable. Depending on the geometry selected, a different performance can be set with regard to the return flow from the intermediate connection and also with regard to the pumping stage in the pumping direction.

According to one embodiment it is provided that the blocking element is designed as a wall and / or as a continuous surface element and / or extends transversely to the pumping direction. This forms a structurally simple way of achieving the advantages according to the invention. The blocking element can in particular extend perpendicular and / or transversely to the pumping direction and / or to the rotor axis. A surface element or a wall can be arranged, for example, parallel to a delimitation of the intermediate connection and / or obliquely or perpendicularly with respect to the rotor axis.

In some embodiments, the blocking element extends in the radial direction only over part of the passage cross section of the pumping stage, in particular with respect to the adjacent, in particular upstream and / or downstream passage cross section before or after the local reduction. In particular, the blocking element can, for example, only extend over a radial part of the passage cross-section with less compression than the respective other part. A radial area left free by the blocking element has, in particular, high compression, but possibly low suction capacity. The high compression favors a low backflow, otherwise the blocking element also reduces the backflow. In particular, the blocking element can cover a radially inner part and / or not cover a radially outer part. For example, a combination with a blocking element or a section of the same blocking element in a different circumferential area extending over the entire radial width is also possible.

According to one embodiment, the pump stage is a turbo molecular pump stage. The turbo-molecular pump stage can for example have one or more turbo rotor disks and / or one or more turbo stator disks. The intermediate connection can, for example, be the turbo molecular pumping stage, in particular a last turbo stator or turbo rotor disk of the pumping stage in the pumping direction, be subordinate. Alternatively, the intermediate connection can be arranged, for example, at the axial height of a turbo rotor disk or open at such a disk, that is to say generally arranged within the pump stage.

According to one embodiment it is provided that the blocking element is designed as part of a turbostator disk. In principle, the blocking element can, for example, be directly connected to a stator disk, in particular a partial stator disk, and / or be axially assigned to such a disk. Axially assigned means that the blocking element is arranged at least partially in the same axial area as the stator disk or partial stator disk. In particular, the blocking element can replace a section of the turbostator disk facing the intermediate connection. Viewed in cross section and at the axial height of the blocking element, stator blades can be provided on one side of the rotor shaft, in particular facing away from the intermediate connection, while the blocking element and in particular no stator blades are provided on another side of the rotor shaft facing the intermediate connection.

According to a structurally simple exemplary embodiment, the blocking element can be designed as a sheet metal. Turbostator disks are often also designed as sheet metal parts and the blocking element can generally be produced or configured in a manner similar to a turbostator disk, but in particular no separate blades are provided.

In a development, it is provided that the blocking element defines a, in particular radially inner, blade base for some or all of the stator blades of a turbostator disk. In particular, a blade base diameter defined by the blocking element can be greater than the blade base diameter of an upstream rotor and / or stator disk; in particular larger by at least 20%.

The blocking element can, for example, be shell-shaped and / or funnel-shaped, in particular part-ring, part-shell and / or part-funnel-shaped, the term "partial" particularly referring to an angular range around the rotor axis. Such a blocking element can in particular be arranged between two spaced-apart disk packs and / or pump stages.

Another embodiment provides that the pump stage is a Holweck pump stage.

The blocking element can preferably be designed as a transverse wall in at least one Holweck groove or a Holweck channel. In general, the blocking element can for example extend perpendicular to the groove or to the channel, to the pumping direction or to the rotor axis. In the following, for the sake of simplicity, reference is only made to a Holweck groove, it being understood that the respective features are also generally valid with regard to a Holweck canal.

According to a further development, it is provided that at least one web, which laterally delimits a Holweck groove, has a clearance with respect to the intermediate connection in an area downstream of the intermediate connection in the pumping direction. In particular, the web does not extend as far as the intermediate connection in the opposite direction to the pumping direction, at least not with its full radial height, but rather the web end is spaced from it. The clearance facilitates the gas inlet from the intermediate connection into the section of the Holweck pumping stage downstream of the intermediate connection in the pumping direction by providing a better conductance for the gas.

In another development, it is provided that at least one web, which laterally delimits a Holweck groove, is exposed to the blocking element in an area upstream of the blocking element in the pumping direction having. This release enables gas particles to be conveyed to pass along the blocking element from one to the next Holwecknut. Thus, the Holwecknut, which has the blocking element, is not blocked in the pumping direction in the sense of a dead end, but the pumping action of the Holwecknut in the area upstream of the blocking element can still be used, in that the particles pass through the opening into the next Holwecknut and are pumped further there can. Thus, in particular, the probability that a particular particle will pass between the blocking element and the Holweck rotor from the relevant Holweck groove to the intermediate connection is reduced, whereby a cross flow from the main inlet or from the Holweck groove to the intermediate connection is avoided. The clearance connects in particular a blocked groove with a next groove in the direction of rotation of the Holweck rotor, this also being able to have a corresponding clearance for the next groove, and so on, until a groove passing through the intermediate connection is reached.

In principle, the intermediate connection with its delimitation can extend over several Holweck grooves and / or be assigned to several Holweck grooves. In an advantageous embodiment, the boundary of the intermediate connection is only assigned to one Holweck groove. An assignment is seen in the fact that the intermediate connection opens into the relevant Holweck groove. An intermediate connection is basically formed on the Holweck stator in that the groove base is open there. The groove base of that Holweck groove to which the intermediate connection is assigned is open. If an intermediate connection is assigned multiple times, the opening extends over several Holweck grooves, in the case of a single assignment only within a Holweck groove. The delimitation of the intermediate connection can in particular only be provided within a Holweck groove. In principle, however, it is also conceivable that the delimitation extends into a web area and / or that the web has a lateral recess defining the delimitation.

Alternatively or additionally, the intermediate connection can, for example, be aligned with at least one delimitation and / or a longitudinal extension parallel to a Holweck groove. In principle, the intermediate connection can also be aligned perpendicular and / or parallel to the rotor axis with at least one delimitation.

A preferred embodiment provides that the intermediate connection with its delimitation is assigned to at least one first Holwecknut and at least one of the next Holwecknut in the direction of rotation of a Holweck rotor is not assigned, a web between the first and the second Holwecknut having a recess that includes the intermediate connection the second Holwecknut connects. The recess can in particular be arranged adjacent to the intermediate connection and / or in the axial region of the intermediate connection. For example, the blocking element can be designed as a transverse wall in the first Holwecknut. In particular, the particles can enter the first Holweck groove freely from the intermediate connection in the pumping direction. In particular, the blocking element blocks the entry of particles into the first Holweck groove against the pumping direction. Through the recess, the particles can in particular freely enter the second Holweck groove, in particular with at least one movement component in the pumping direction.

The first Holweck groove or generally one of the Holweck grooves to which the intermediate connection is assigned with its delimitation can generally preferably be separated from a Holweck groove next to the direction of rotation of the Holweck rotor, in particular a third Holweck groove, in particular by a web, at least in an axial area of the intermediate connection.

In general, several intermediate connections can also be made on one pump stage or between or on several pump stages, in particular Holweck and / or Turbomolecular pumping stages may be provided. In general, the pump can have several, in particular different, pump stages, which are preferably connected in series.

More generally, the pump can e.g. have a pumping-active rotor section upstream of the intermediate connection with respect to the pumping direction and a pumping-active rotor section downstream with respect to the pumping direction, wherein in particular both rotor sections can be connected to the same rotor shaft and / or connected in series. In general, the vacuum pump can, for example, have only one rotor shaft, wherein in particular all pump stages and pump stage sections can be driven by the rotor shaft and / or can be connected in series.

In general, the intermediate connection can preferably open into an axial region, in particular in a pump housing, via which the pump stage or pump stage section upstream of the intermediate connection is connected in series with a pump stage or pump stage section downstream of the intermediate connection. This axial area can be, for example, an intermediate stage area or an axial area within a pump stage, for example an axial area of a turbo rotor disk. In general, gas can be conveyed in particular over the axial region into which the intermediate connection opens and / or over the intermediate stage region. In particular, the blocking element is passed by the gas through the remaining passage cross section in the pumping direction.

According to a further embodiment, it is provided that the blocking element and / or a stator element which is arranged on the intermediate connection and which has the blocking element is produced by means of a generative manufacturing process, in particular 3D printing. This enables a largely free and targeted design of the blocking element with regard to its blocking effect, so that the advantages according to the invention can be effectively achieved with simple means. Generative manufacturing processes are understood to mean the manufacture or shaping of a component by joining volume elements such as layers. The generative manufacturing method preferably comprises that the component is manufactured according to at least one of the methods stereolithography, laser melting, laser sintering, selective laser sintering, layer laminate method, extrusion, fused deposition modeling, laminated object modeling or 3D printing.

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

eine Turbomolekularpumpe des Standes der Technik mit einem Zwischenanschluss,

Fig. 7

einen Distanzring für eine Turbomolekularpumpe,

Fig. 8

eine Turbomolekularpumpe gemäß einer Ausführungsform der Erfindung,

Fig. 9

eine Turbomolekularpumpe gemäß einer weiteren Ausführungsform,

Fig. 10

eine übliche Turbostatorscheibe in einer Draufsicht,

Fig. 11

ein Blockierelement für eine Turbomolekularpumpstufe in einer Draufsicht,

Fig. 12

eine Auftragung der Kompression einer Turbostatorscheibe in Abhängigkeit von einer radialen Position,

Fig. 13

eine Ausführungsform eines Blockierelements,

Fig. 14

einen Stator einer bekannten Holweckpumpstufe,

Fig. 15

einen Stator einer Holweckpumpstufe gemäß einer Ausführungsform der Erfindung,

Fig. 16

einen Stator eine Holweckpumpstufe gemäß einer weiteren Ausführungsform.

The invention is described below by way of example on the basis of advantageous embodiments with reference to the accompanying figures. They show, each schematically:

Fig. 1

a perspective view of a turbo molecular pump,

Fig. 2

a view of the underside of the turbo molecular pump of 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 prior art turbo molecular pump with an intermediate connection,

Fig. 7

a spacer ring for a turbo molecular pump,

Fig. 8

a turbo molecular pump according to an embodiment of the invention,

Fig. 9

a turbo molecular pump according to a further embodiment,

Fig. 10

a conventional turbostator disk in a top view,

Fig. 11

a blocking element for a turbo molecular pumping stage in a plan view,

Fig. 12

a plot of the compression of a turbostator disk as a function of a radial position,

Fig. 13

an embodiment of a blocking element,

Fig. 14

a stator of a well-known Holweck pump stage,

Fig. 15

a stator of a Holweck pump stage according to an embodiment of the invention,

Fig. 16

a stator a Holweck pump stage according to a further embodiment.

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. 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.

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 there is also a sealing gas connection 135, which is also referred to as a purge gas connection, via which purge gas is used to protect the electric motor 125 (see e.g. Fig. 3 ) can be brought 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.

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 so that it also operates can be taken if it is oriented in a different way than in 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.

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.

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 turbomolecular pump 111 comprises several turbomolecular pump stages connected in series with one another with a plurality of 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 one turbomolecular pumping stage. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

The vacuum pump also includes Holweck pump stages which are arranged one inside the other in the radial direction and are connected in series with one another for effective pumping. The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical-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 forms with this 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. Also, at the top of the In the inner Holweck stator sleeve 169, a radially running channel can be provided, 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, a connection channel 179 to the outlet 117 can also be provided.

The aforementioned pump-active surfaces of the Holweck stator sleeves 163, 165 each have a plurality of Holweck grooves running spirally 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 magnet bearing 183 in the area of the pump inlet 115.

In the area of the roller bearing 181, a conical injection 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. The operating medium storage comprises a plurality of absorbent disks 187 stacked on top of one another, which are provided 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 reservoir 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 carrier 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 203. 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 idle 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, since 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 so that a collision of the structures on the rotor side with the structures on the stator side 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 portion 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 influence each other magnetically.

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 the vacuum pressure produced by the backing pump connected to the pump outlet 117 prevails in the engine compartment 137 at least approximately.

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 in order to achieve better sealing of the motor compartment 217 from the radially outside Holweck pump stages.

Some of the pumps and systems described below are shown in a highly schematic and simplified manner. For the purpose of practical implementation, they can advantageously be implemented with one or more features of the pump described above.

In Fig. 6 a vacuum pump 20 is shown, which is designed as a turbomolecular vacuum pump. The schematic illustration shows a rotor shaft 22 to which a plurality of turbo rotor disks 24 are connected and which, during operation, rotates together with the turbo rotor disks 24 about a rotor axis that is perpendicular here. Turbostator disks 26 are provided between the turbo rotor disks 24. Together they cause a gas to be conveyed along a pumping direction 28 indicated here by an arrow.

The vacuum pump 20 comprises an intermediate connection 30, which is indicated here in a simplified manner as an arrow. The intermediate connection 30 is arranged approximately at the axial height of one of the turbo rotor disks 24, that is to say opens into its axial or effective area.

In Fig. 6 no turbo stator disks 26 are shown downstream of the intermediate connection 30 in the pumping direction. It goes without saying, however, that turbostator disks 26 can also be provided there.

A known stator disk 24 is arranged upstream of the intermediate connection 30 in the pumping direction 28. Although the pump 20 delivers in the pumping direction 28, it is possible to a certain extent that particles of one at the intermediate connection 30 pending gas move against the pumping direction 28 after entering the vacuum pump 20. The particles can also pass through the turbostator disk 26 arranged upstream of the intermediate connection 30 and, in principle, also through further turbo rotor disks 24 and turbostator disks 26. There is thus a certain return flow 32, which is indicated here by an arrow.

Fig. 7 shows a spacer ring 34, which can be provided, for example, for the spaced mounting of two turbostator disks 26. The spacer ring 34 has a recess 36 which defines a delimitation for an intermediate inlet, for example the intermediate inlet 30 or one of the intermediate inlets described below.

It is an object of the invention to reduce backflow 32. In general, the gas should be pumped out as well as possible from the intermediate connection 30 and / or should not flow back. In particular, a structural change to the rotor, in particular the turbo rotor disks 24, can be undesirable. If possible, it should be possible to retain an existing rotor construction. In particular, the invention pursues the approach of increasing the internal compression between the intermediate connection and the main inlet, that is to say the first inlet in the pumping direction, and of making a structural change, in particular on static components.

Evaluations of measurements have shown that the inflow distribution has a great influence on the further return flow. With the type of intermediate connections discussed here, the gas usually flows radially onto a rotor disk, as shown in FIG Fig. 6 the case is. If, for example, the upstream stator disk is covered in the angular area assigned to the intermediate connection by a blocking element, for example a partial shell, in particular a half-shell, or a partial ring, in particular a half ring, significantly less gas can flow back and is guided more downstream in the turbo disk package. One such approach is in the Figs. 8,9 and 11 illustrated.

In Fig. 8 is a vacuum pump 20 designed as a turbo molecular pump in one of the Fig. 6 Similar representation shown, the reference numerals being used accordingly. A blocking element 38 is provided upstream of the intermediate connection 30 in the pumping direction 28. This is designed, for example, as a continuous surface or wall and extends only around a partial angular range of the rotor shaft 22. A turbostator disk 26 is provided in the remaining partial angular region of the relevant axial region.

The blocking element 38 prevents a backflow 32, as shown in FIG Fig. 6 is indicated. The movement of the particles is indicated here by an arrow 40. Such particles which initially move counter to the pumping direction 28 from the intermediate connection 30 strike the blocking element 38 and cannot move any further counter to the pumping direction 28. After desorption from the blocking element 38, a respective particle has a fundamentally statistically distributed direction of movement, which, however, runs in the pumping direction 28 with at least one component in particular. The blocking element 38 thus reduces the probability that a particular particle will move in the vacuum pump 20 against the pumping direction 28.

The turbostator disks 26 are axially permeable, that is, in the pumping direction 28, although not in such a way that the particles can fly exactly axially, but in such a way that the gas can be conveyed axially between the positioned stator blades. The turbostator disks 26 therefore have a passage cross section. The passage cross-section of the turbostator disks 26 is constant over the axial extent of the only turbomolecular pump stage 41 here, but with the exception of that axial region in which the blocking element 38 is arranged. The blocking element 38 is impermeable and / or closed and therefore reduces the passage cross section of the pump stage in a locally limited axial area, namely in the pumping direction 28 directly in front of the intermediate connection 30.

It should be noted that the blocking element 28 is shown here significantly thicker than the turbo stator disks 26. However, this is only used for distinguishing the illustration. In fact, the blocking element 38 can be designed as, in particular thin, sheet metal, and in particular even thinner than the stator disks 26.

The vacuum pump 20 of the Fig. 9 has two axially spaced disk packs which form a first turbo-molecular pump stage 42 and a second turbo-molecular pump stage 44. Between the pump stages 42 and 44 there is an intermediate stage region 46 into which the intermediate connection 30 opens. Unlike in Fig. 8 The intermediate connection 30 does not open onto a turbo rotor disk 24, for example, but into a free space between the pump stages 42 and 44. This is advantageous with regard to the conductance and the pumping speed at the intermediate connection 30 and can be used in particular when a large effective Pumping speed is desired and / or the conductance in the area of the intermediate connection 30 should be large.

A blocking element 38 can, for example, be oriented obliquely to the rotor axis or rotor shaft 22 and / or to the pumping direction 28 in relation to a longitudinal section. In principle, the blocking element 38 can act as a guide element, in particular it can be designed as a guide plate. The particles can thus be guided particularly advantageously in the pumping direction 28.

A blocking element 38, for example according to Fig. 8 or Fig. 9 , can be designed, for example, as a partial ring, in particular a half ring, which is located on a side of the rotor axis or the rotor shaft 22 facing the intermediate connection 30 arranged and / or can be arranged in an angular range associated with the intermediate connection 30 in relation to the rotor axis.

In Fig. 10 a typical turbostator disk 26 is shown, for example, shown in FIGS Figures 8 and 9 one of the upper two turbostator disks 26 or in Fig. 6 one of the three illustrated turbostator disks 26 can accordingly. The turbostator disk 26 of the Fig. 10 is shown in a top view, the viewing direction running parallel to the pumping direction and to the rotor axis. The turbostator disk 26 comprises a plurality of turbostator blades 48 distributed over its circumference, between which the particles of the gas to be conveyed can pass. The gaps between the turbostator blades 48 thus form a passage cross-section, however the gaps are not only formed by the free areas between the stator blades 48 that are visible here, but also partially extend below or above the stator blades 48 due to the angle of incidence of the stator blades 48 which is not visible here Stator blades 48.

In Fig. 11 is one of those who Fig. 10 A similar perspective is chosen, a turbostator disk 26 being visible, which here only fills a partial angular range. The remaining partial angular range is covered by a blocking element 38. An intermediate connection 30 is indicated, the blocking element 38 being provided upstream of the intermediate connection 30 in the pumping direction. The pumping direction runs towards the viewer here.

The blocking element 38 is designed as a continuous surface element, for example as sheet metal. In this embodiment it forms a partial ring, which here extends, for example, over approximately 180 ° around the rotor axis.

The blocking element 38 itself does not have a passage cross section or is embodied to be impermeable. The passage cross section of the pumping stage is therefore local reduced in the axial area shown here, namely by way of example to that angular area in which the blocking element 38 is not arranged or which the blocking element 38 does not cover.

As with Fig. 11 It is easy to see that the passage cross-section is here in particular locally asymmetrical with respect to the rotor axis. On a side of the rotor axis facing the intermediate connection 30, the blocking element 38 blocks a larger proportion of the passage cross section than on a side of the rotor facing away from the intermediate connection 30. The angular area which the blocking element 38 covers is arranged in particular such that the intermediate connection 30 is arranged at least essentially in the middle of the angular area.

The blocking element 38 according to Fig. 11 can for example in relation to a longitudinal section according to Fig. 8 or Fig. 9 be trained. In particular, the blocking element 38 can be designed, for example, as a flat surface element and / or extend perpendicular to the rotor axis. Alternatively, the blocking element 38 can taper, for example be designed in the form of a part funnel and / or part shell, in particular as a half funnel or half shell. In general, the blocking element 38 can in particular be designed in the form of a partial ring.

In principle, the blocking element 38 can, for example, simply be a normal turbostator disk, such as that of the Fig. 10 , cover or replace the corresponding cross-sectional area. In the latter case, a partial stator disk 26 is provided, in particular, which is connected in particular to the blocking element 38 and / or is axially assigned to it.

Another approach to reducing the return flow is to use a stator disk in the relevant section, which has a particularly high compression and thus a blocking effect. In Fig. 12 is qualitatively the The course of the compression for a typical turbostator disk is plotted along the radial extent of a respective turbostator blade. The horizontal axis shows the radius R of a radial position and the vertical axis shows the compression K. The curve, which is shown here in simplified form as a straight line, illustrates that the compression K is greatest in a radially outer region 49.

For example, only the radially outer region 49 of a stator disk can be used. Only particles with a very large momentum pass through the rotor disk into this area; it is an area with high compression. In contrast, the radially inner area has a lower compression, in particular because of the lower peripheral speed. Thus, only a high level of compression is preferably permitted by utilizing a specific radial area.

The in Fig. 12 illustrated context uses the embodiment of Fig. 13 out. Here, a blocking element 38 covers a radially inner region of the rotor blades 48 if it is assumed that the stator disk 26 is otherwise like that of the Fig. 10 is constructed. In principle, however, the stator blades 48 do not have to extend into the radial region of the blocking element 38. Rather, it is intended to illustrate that the blocking element 38 advantageously reduces the passage cross section locally to a passage cross section that has a larger inside diameter than the other passage cross section of the pumping stage or than the passage cross section of an upstream turbo rotor or turbostator disk. In this embodiment, the blocking element 38 thus effectively defines the inside diameter of the passage cross section and the respective blade bottoms 51 between the turbostator blades 48.

This embodiment also reduces a backflow of gas particles from the intermediate connection 30. While in the Figs. 8,9 and 11 a blocking element 38 is arranged in particular "in the path" of the particles in order to reduce a backflow, a passage cross-section with low compression is covered or only a passage cross-section with high compression is left, even if it extends directly above the intermediate connection. The high compression itself ensures a low probability that a particle will pass through the passage cross-section against the pumping direction. A region with less compression, namely the radially inner region, would have a relatively high probability of a particle passing through, but is covered by the blocking element 38.

Typically, the blade bases of the individual turbo rotor and turbostator disks of a pump stage and / or of a pair of rotor disks and stator disks assigned to one another are of comparable diameters. In particular, a blade base diameter is therefore essentially the same or similar. In principle, the passage cross-sections within a pumping stage are often similar. This is particularly useful so that the discs have approximately the same suction capacity. For applications in which only or primarily high compression and / or only low pumping speed are required, only the radially outer area 49 of the stator disks can preferably be used. This is exemplary in the embodiment of FIG Fig. 13 the case. In principle, it is possible for this purpose to use existing stator disks, for example as in FIG Fig. 10 illustrated, easy to cover. Alternatively, a stator disk can be provided, the stator blades of which only extend over the desired radial area. In general, the, in particular effective, blade base diameter of the stator disk upstream of the intermediate connection 30 can differ, preferably clearly, from that of another stator and / or rotor disk, in particular the stator disk upstream of this stator disk.

In Fig. 14 a Holweck pumping stage 50 is shown in such a simplified manner that a Holweck stator 52 is conceptually developed and shown as a flat surface. The Holweck stator 52 comprises several Holweck grooves 54 which are laterally bounded by webs 56 and separated from one another. A Holweck rotor (not shown here, in particular a Holweck sleeve) rotates relative to the Holweck stator 52 in a direction of rotation 58 indicated by an arrow. The Holweck rotor therefore moves from right to left over the stator 52 in this idealized view. This creates a pumping effect along a pumping direction 28.

An intermediate connection 30 is provided within the Holweck pump stage 50, which is designed as a recess, in particular as a milled elongated hole, in the Holweck stator 52. The intermediate connection 30 is arranged downstream of a first section of the Holweck pump stage 50 in the pumping direction 28 and upstream of a second section of the pump stage 50 in the pumping direction 28.

Although the Holweck pumping stage 50 effects a delivery of gas along the pumping direction 28, a movement of gas particles starting from the intermediate connection 30 into the first section of the Holweck pumping stage 50 and thus against the pumping direction 28 is basically possible. The pumping stage 50 of the Fig. 14 thus points - similar to that of Fig. 6 - The risk of a backflow 32, which should be avoided.

For this purpose, the Holweck pump stage 50 has the Fig. 15 a blocking element 38. Otherwise, the similarly represented elements are constructed accordingly with the same reference numerals. The pumping direction 28 and the direction of rotation 58 run according to the arrows in FIG Fig. 14 .

The blocking element 38 is designed here as a transverse wall which blocks several Holweck grooves 54, namely those with which the intermediate connection 30 is connected associated with its limitation. Particle movement starting from the intermediate connection 30 counter to the pumping direction 28 and into the sections of the Holweck grooves 54 upstream of the intermediate connection 30 is thus effectively restricted.

In principle, the blocking element 38 can be designed, for example, as a horizontal web and / or block the Holweck grooves 54 directly adjoining the intermediate connection 30 with respect to the intermediate connection.

Due to the blocking element 38, there is a significantly reduced probability for particles to flow back directly from the intermediate connection 30 against the pumping direction 28. In particular and in general, a turbo-molecular pump stage can be provided upstream of a Holweck pump stage 50. Thus, the blocking element 38 in the Holweck pumping stage 50 reduces the risk of a backflow to the turbo molecular pumping stage. One of the effects is, for example, an increase in the pressure ratio between the intermediate connection and the connection or port that is next opposite to the pumping direction 28. This can, for example, be an intermediate connection on or after a turbo-molecular pump stage or, in principle, also a main inlet.

A passage cross section of the pump stage 50 is formed for a given axial area by the sum of the cross sections of the Holweck grooves 54. Some of the Holweck grooves 54 or their cross-sections are blocked by the blocking element 38. The other Holweck grooves 54, however, remain open. In this context it should be mentioned that Figures 14 to 16 show the unwound Holweck stator 52 in particular only partially and that further Holweck grooves 54 and webs 56 are preferably provided. Rather, the illustrations concentrate on the area of the intermediate connection 30, which in particular does not have to extend around almost the entire Holweck stator 52.

The blocking element 38 blocks the passage cross section, in particular in an angular range associated with the intermediate connection 30 with respect to the rotor axis.

In this embodiment, the intermediate connection 30 is aligned with at least one of its boundaries and with its longitudinal extension perpendicular to the rotor axis. Other orientations, for example perpendicular to the webs 56, are also possible.

In an area 60 downstream of the intermediate connection 30 in the pumping direction 28, several webs 56 are exposed to the intermediate connection 30, i.e. do not extend to the intermediate connection 30, but end at a certain distance from the intermediate connection 30, which corresponds to the width of the area 60 identified here . The clearances or the free area 60 allow the gas to flow more easily from the intermediate connection 30 into the downstream sections of the Holweck grooves 54, in that the conductance is increased. This also improves the pumping action and the risk of backflow and is advantageously supplemented with the action of the blocking element 38.

In the area 60, the Holweck webs in particular are specifically removed directly below the intermediate connection. As a result, the pumping speed to be achieved there is increased in that the inflow area into the section of the Holweck pump stage 50 downstream of the intermediate connection is increased.

Several of the webs 56 also have a clearance 62 with respect to the blocking element 38 in an area upstream of the blocking element 38. The webs 56 therefore do not extend in the pumping direction 28 to the blocking element 38 or end at a certain distance therefrom. The clearances 62 form a connection between a Holwecknut 54 and blocked by the blocking element 38 a Holweck groove 54 that is closest in the direction of rotation 58 of the Holweck rotor 52.

The blocking element 38 extends here over several Holweck grooves 54 and so many clearances 62 are provided that all Holweck grooves 54 blocked by the blocking element 38 are connected to a non-blocked or free Holweck groove 54. The Holweck grooves 54, which are blocked by the blocking element 38, therefore do not form a dead end, but the particles conveyed by them can flow off to a continuous Holweck groove 54 and be pumped further there. In this way, in particular the loss of pumping speed resulting from the blocking element 38 can be at least partially compensated for.

Particularly in combination, the blocking element 38, the clearances in the area 60 and the clearances 62 lead to a particularly strong reduction in the return flow from the intermediate connection 30 in the direction of the high vacuum side, i.e. against the pumping direction 28, with a simultaneous increase in the pumping speed at the intermediate connection 30.

Fig. 16 shows a further embodiment of a Holweck pump stage 50 with several Holweck grooves 54 which are laterally limited or separated by webs 56. The pumping direction 28 and the direction of rotation 58 of the Holweck rotor, not shown here, are indicated by arrows and run according to the Figures 14 and 15 .

The embodiment of the Fig. 16 comprises two intermediate connections 30, which are arranged and designed similarly, which is why the following explanations are limited to the left one of the intermediate connections 30 shown here. It goes without saying, however, that in principle one or more such intermediate connections 30 can be provided and the number selected here is an example.

In this embodiment, the intermediate connection 30 is assigned to only one Holweck groove 54. Its delimitation therefore does not extend over several Holweck grooves 54. The intermediate connection 30 is advantageously arranged with its delimitation essentially parallel to this Holweck groove 54.

Arranged upstream of the intermediate connection 30 in the pumping direction 28, a blocking element 38 is provided which restricts a backflow along the relevant Holweck groove 54. The Holweck groove 54 in question is connected to the next Holweck groove 54 in the direction of rotation 58 via an opening 62 of a web 56 laterally delimiting the groove 54, so that gas particles from the Holweck groove 54, which is blocked by the blocking element 38 and to which the intermediate connection 30 is assigned, are not get into a dead end, but are pumped out through the next Holwecknut 54.

The movement of the gas particles is indicated here schematically by dotted arrows. From the intermediate connection 30, the particles can flow, on the one hand, into a section of the Holweck groove 54 downstream of the intermediate connection 30, to which the intermediate connection 30 is assigned. The web 56, which is arranged between the relevant Holweck groove 54 and the next Holweck groove 54 in the direction of rotation 58, has a recess 64 which connects the Holweck grooves 54 to one another. On the other hand, a respective particle can also get from the intermediate connection 30 into the next Holweck groove 54 in the direction of rotation 58. The intermediate connection 30 is thus opposed to a low conductance, so that an inflow of gas into the Holweck pump stage 50 is facilitated.

In principle, the goal in particular is to reduce the probability of entry and again immediate exit through the same intermediate connection 30. The more obliquely the intermediate connections 30 are arranged, the lower the probability that a particle will leave the intermediate connection 30 again directly after hitting the rotating Holweck sleeve, since the horizontal width of the duct is lower than with an intermediate connection according to Fig. 14 or 15 . In addition to the inclined position of the intermediate connection, it is advantageous that the webs have been removed in the direction of the desired conveying direction. In the left half of the Fig. 16 can be seen from the arrows that the majority of the particles decide for the path in the pumping direction. The particles move either directly into the associated Holweck groove 54 or through the preferred direction after hitting the Holweck sleeve into the neighboring Holweck groove 54. To the right and above the respective intermediate connection 30, the blocking element 38 prevents a particle from being transported in the direction of the high vacuum side. The exposure 62 advantageously serves to ensure that particles from the Holweck groove 54 blocked by the blocking element 38 get into the neighboring Holweck groove 54, and that the conveyance in the pumping direction can thus be maintained.

In general, it is possible to make the geometry of a blocking element 38 changeable, in particular in order to achieve an optionally different performance with regard to backflow.

In particular, the Holweck stators 52 of Fig. 15 and 16 have a very complex geometry and can therefore preferably be produced in a particularly simple manner by means of 3D printing or generally by a generative manufacturing process. In principle, the other stators and / or blocking elements presented here can also be produced by means of a generative process, such as, for example, 3D printing.

Reference list

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 disc

157

Stator disk

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

rotor-side bearing half

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

20th

Vacuum pump

22nd

Rotor shaft

24

Turbo rotor disk

26th

Turbo stator disc

28

Pumping direction

30th

Intermediate connection

32

Backflow

34

Intermediate connection

36

Recess / limitation

38

Blocking element

40

Particle motion

41

Turbo molecular pumping stage

42

first pumping stage

44

second pumping stage

46

Intermediate level area

48

Turbostator blade

49

Area

50

Holweck pumping stage

51

Shovel bottom

52

Holweck stator

54

Holwecknut

56

web

58

Direction of rotation

60

Area / exemption

62

exemption

Claims (15)

Molecular vacuum pump (20) with
at least one molecular pumping stage (41, 42, 50) by means of which a gas can be conveyed from an inlet to an outlet of the molecular vacuum pump (20),
wherein the pumping stage (41, 42, 50) has a pumping direction (28) and transversely to the pumping direction (28) has a passage cross section; and
an intermediate connection (30) which is arranged downstream within the pump stage (41, 50) or the pump stage (42),
an in particular static blocking element (38), by means of which the passage cross section is locally reduced, is arranged in front of the intermediate connection (30) in the pumping direction (28). Molecular vacuum pump (20) according to claim 1,
wherein the blocking element (38) is arranged on a side of a rotor shaft (22) of the pump stage facing the intermediate connection (30); and / or wherein the geometry of the blocking element (38) can be changed. Molecular vacuum pump (20) according to claim 1 or 2,
wherein the blocking element (38) is designed as a wall and / or as a continuous surface element and / or wherein the blocking element (38) extends transversely to the pumping direction (28). Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the blocking element (38) extends in the radial direction only over a part of the passage cross section of the pump stage. Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the pumping stage (41, 42) is a turbo-molecular pumping stage. Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the blocking element (38) is designed as part of a turbostator disk (26), is directly connected to a turbostator disk (26) and / or is axially assigned to a turbostator disk (26), in particular a partial stator disk;
and / or wherein the blocking element (38) is designed as a sheet metal. Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the blocking element (38) defines a blade base (51) for some or for all stator blades (48) of a turbostator disk (26). Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the blocking element (38) is partially shell-shaped and / or partially funnel-shaped. Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the pumping stage (50) is a Holweck pumping stage. Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the blocking element (38) is designed as a transverse wall in at least one Holwecknut (54). Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein at least one web (56), which laterally delimits a Holweck groove (54) and / or separates adjacent Holweck grooves (54) from one another, in an area (60) downstream of the intermediate connection (30) in the pumping direction (28), an area (60) with respect to the intermediate connection ( 30). Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein at least one web (56) which laterally delimits a Holweck groove (54) and / or separates adjacent Holweck grooves (54) from one another, in an area upstream of the blocking element (38) in the pumping direction (28), a clearance (62) with respect to the blocking element ( 38). Molecular vacuum pump (20) according to at least one of the preceding claims,
the intermediate connection (30) with its delimitation being assigned to only one Holwecknut (54);
and / or wherein the intermediate connection (30) is aligned with at least one delimitation and / or a longitudinal extension at least substantially parallel to a Holweck groove (54). Molecular vacuum pump (20) according to at least one of the preceding claims,
The intermediate connection (30) with its boundary is assigned to at least one first Holweck groove (54) and at least one of the next Holweck groove (54) in the direction of rotation of a Holweck rotor is not assigned, a web (56) between the first and the second Holweck groove being a recess which connects the intermediate connection (30) to the second Holwecknut (54). Molecular vacuum pump (20) according to at least one of the preceding claims,
wherein the blocking element (38) and / or a stator element (26, 52) which is arranged on the intermediate connection (30) and which has the blocking element (38) is produced by means of a generative manufacturing process, in particular 3D printing.

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