EP3734078A2 - Turbomolecular pump and method of manufacturing a stator disc for such a pump - Google Patents

Abstract

The invention relates to a turbomolecular pump comprising: a rotor with a plurality of rotor blades distributed over its circumference, which can be driven to rotate about an axis of rotation in order to generate a pumping effect, and at least one stator disk, which has a plurality of rotor blades distributed over its circumference Having stator blades and with which the rotor cooperates to generate the pumping action; wherein the stator blades of the stator disk are oriented obliquely with respect to a disk plane which runs perpendicular to the axis of rotation of the rotor, wherein the stator disk is made of sheet metal, and wherein at least one stator blade has a flattening at one axial end.

Description

The present invention relates to a turbomolecular pump comprising: a rotor with a plurality of rotor blades distributed over its circumference, which can be driven to rotate about an axis of rotation in order to generate a pumping effect, and at least one stator disk which distributes a plurality of over its circumference having arranged stator blades and with which the rotor cooperates to generate the pumping action, the stator blades of the stator disk being oriented obliquely with respect to a disk plane which runs perpendicular to the axis of rotation of the rotor.

The invention also relates to a method for producing a stator disk with a plurality of stator blades distributed over its circumference for a turbo molecular pump.

Stator disks for turbo-molecular pumps are usually either machined from a solid material, e.g. milled or sawn, or made from sheet metal. When manufactured from sheet metal, the stator blades are typically punched out and then aligned obliquely with respect to a disk plane by bending. The plane of the disk is one which, when the pump is assembled, is perpendicular to the axis of rotation of the rotor, and is e.g. defined by at least one collar of the stator disk.

The production of stator disks from sheet metal is particularly cost-effective, but has the disadvantage that, with comparable performance, more axial installation space is necessary for stator disks made from sheet metal than for stator disks produced by machining. The reason for this is that the different manufacturing processes lead to different geometries of the stator blades.

It is an object of the invention to reduce the axial installation space of a stator disk made of sheet metal, in particular without restricting the vacuum performance.

One approach that is obvious in this context would be to simply align the stator blades “less obliquely”, that is to say to reduce their angle with respect to the disk plane. However, this has considerable effects on the pumping action of the stator disk and thus on the vacuum performance.

Rather, the object is achieved by a turbomolecular pump with the features according to claim 1, and in particular in that at least one stator blade has a flattening at at least one axial end.

As a result, the material of the stator blade is flattened in particular exactly where it defines the axial installation space of the stator blade on the one hand and plays a relatively minor role in relation to the pumping performance, in particular has at least essentially no active pumping effect, on the other. In addition, such a flattening can be produced with simple means, so that the invention enables the installation space to be optimized with at least essentially constant pumping performance with means that are particularly simple in construction.

The flattening can be produced by removing material or by displacing it. This is discussed in more detail elsewhere.

The term "axial" generally refers to the axis of rotation of the rotor or a direction parallel to it. The axial end is thus located axially on highest or lowest point of the stator vane in an upright pump. A pumping direction is typically also at least substantially parallel to the axis of rotation, so that the axial ends of the stator disk in particular form an upstream end and a downstream end.

The at least one stator vane can e.g. have a flattening only at one axial end or it can e.g. a flattening can be provided at two opposite axial ends.

According to one embodiment it is provided that the flattening comprises an at least essentially flat surface. Such a surface can be produced with simple means and thus enables a relatively large amount of space to be saved in a simple manner.

The surface can preferably run at least essentially parallel to the plane of the pane. This enables a particularly large saving in installation space.

More preferably, the flattening can extend over the entire length of the stator blade. The length of the stator blade corresponds to its extension in at least an essentially radial direction, the term "radial" referring to the axis of rotation of the rotor.

In general, the axial end can be an upstream end or a downstream end of the stator blade. However, it is also possible for both an upstream end and a downstream end of the stator blade to have a flattening. In this case, the space saving can be achieved twice.

Preferably, several or all of the stator blades of the stator disk can have a flattening, in particular at the corresponding axial end, that is to say all at the upstream and / or at the downstream end. A turbo molecular pump often has several stator disks. It is particularly advantageous here if several or all of the stator disks have flattened stator blades.

The object of the invention is also achieved by a method for producing a stator disk according to the independent claim directed thereto. This is used to produce a stator disk with a plurality of stator blades distributed over its circumference for a turbomolecular pump, in particular one of the type described above, and includes that the stator disk is made of sheet metal, the stator blades of the stator disk in relation to a plane of extension of the sheet metal be aligned obliquely, and that at least one stator blade is flattened at at least one end with respect to a normal to the plane of extension of the sheet metal. In general, the invention also comprises a corresponding manufacturing method for a turbo molecular pump with a stator disk manufactured in this way.

The plane of extension of the sheet metal preferably corresponds to a disk plane which, in particular when the pump is assembled, is perpendicular to the axis of rotation. In particular, when aligning the stator blade, a collar, which carries the stator blade, remains in the plane of extent of the sheet metal. In this case, reference can be made to the federal level. The normal is in particular aligned parallel to the axis of rotation of the rotor when the pump is assembled.

According to a further development it is provided that the flattening comprises a forming, in particular cold forming and / or pressing. In particular, the stator blade is not bent flat, but is essentially compressed in the cross section of the stator disk. In general, in particular, the material is deformed in a flowing manner and / or by extrusion. The material is generally preferred pushed onto the stator blade, in particular so that it rises up in an area adjacent to the axial end. In principle, for flattening, for example, a forming and / or pressing force can be applied to the stator blade or to the end, at least substantially parallel to the normal or axis of rotation of the rotor. During the flattening, the stator blade can preferably be supported on a flat side facing away from the flattening, preferably flat.

Alternatively or additionally it is e.g. also possible to machine or manufacture the flattening, for example by grinding.

In general, the flattening can take place in particular at a corner of a cross section of the stator blade. In general, a section of material is preferably removed from its position at the relevant corner, either displaced by reshaping or, for example by cutting, separated from the stator blade. The section of material to be removed is preferably at least substantially triangular in cross section. The above-mentioned surface of the flattening defines, in particular, one side of this triangle, namely in particular one which, based on the cross section of the stator blade, faces a centroid of the same.

In general, the stator blade can in particular have a first flat side which points in the same direction with respect to the normal as the flattened end, and / or a second flat side which points opposite to this direction. With regard to the pumping direction, these are in particular an upper or first side in the pumping direction and a lower or second side in the pumping direction. It goes without saying that the flat sides are generally aligned obliquely, but face one of the two opposite directions along the normal, that is, they point in the corresponding direction.

According to one embodiment, it is provided that the flattening includes that a material of the stator blade, in particular mainly, is shifted, in particular flowing, in the direction of the first flat side. With reference to the turbo-molecular pump described above, this means in particular that the stator blade has an accumulation of material on a first flat side which points in the same direction with respect to the axis of rotation of the rotor as the flattened end. This can in particular form a projection and / or a bead and / or in particular be arranged directly next to the flattening. The first flat side is in particular an upper side of the blade in the upright pump and / or an upstream flat side, in particular the relevant end being an upstream end. For example, however, the downstream end can also be flattened, in particular with an accumulation of material being generated on the downstream flat side.

In general, for example, stator blades can be formed by stamping and / or aligned obliquely by bending. The flattening can e.g. be an additional process step or part of an additional process step or, in principle, also be provided in a process step with the shaping and / or alignment. Basically, the flattening can take place in particular before, during and / or after the punching and / or bending.

A further aspect of the invention proposes a turbo molecular pump according to claim 11. This can for example be designed and / or manufactured or manufactured according to the type described above and comprises a rotor with a plurality of rotor blades distributed over its circumference, which can be driven to rotate around an axis of rotation in order to generate a pumping effect, and at least one stator disk which has a plurality of stator blades distributed over its circumference and with which the rotor interacts to generate the pumping effect. The stator blades of the stator disk are in relation to a disk plane which is perpendicular to the axis of rotation of the rotor, oriented obliquely, the stator blades being carried by at least one collar, in particular an inner and / or outer collar. The collar is arranged axially eccentrically with respect to at least one stator blade. In particular, the collar can be arranged axially eccentrically with respect to all stator blades of the stator disk.

The collar is therefore in particular not arranged at the level of the axial center of the blade, but is axially offset to it. The off-center arrangement enables the assembly and, in particular, the disassembly of the pump to be simplified. The eccentric arrangement of the collar makes it easier to remove the stator disk from the pump.

In particular in such an arrangement, in which the stator disk is led out radially between two rotor disks for the purpose of dismantling or is introduced for the purpose of assembly - the stator disk has in particular at least two separable ring segments - the axial side to which the collar is offset is hereby shifted , the risk of collision with another stator element, in particular a spacer ring, is reduced because the stator blades there are then axially shorter. Although this would theoretically increase the risk of collision on the other axial side, a certain assembly sequence usually allows no such element, in particular a spacer ring, to be arranged on this other axial side when the stator disk in question is "the turn" for removal.

It can preferably be provided that the collar, a connection point between the collar and the respective stator blade and / or an axial center of the collar are arranged before or after the axial center of the stator blade in relation to a pumping direction. With an upright pump, this corresponds in particular to an arrangement above or below the axial center of the stator blade.

A stator disk can e.g. have an outer collar and / or an inner collar. In principle, an outer and an inner collar of the stator disk can be arranged at the same or different axial height. The terms “outside” and “inside” relate here to the axis of rotation of the rotor, that is to say radially outside and radially inside.

In some embodiments, the collar is arranged axially eccentrically with respect to several, in particular all, stator blades. This preferably applies to the entire collar and / or to an outer and / or inner collar. In general, the stator blades can in particular be arranged at the same axial height.

In principle, a collar can be designed, for example, ring-shaped, in particular continuously ring-shaped or with several ring segments. E.g. An inner collar can be formed in a continuous ring shape and an outer collar with several ring segments. It should be noted that the stator disk itself can preferably be made from ring segments, i.e. “Continuous” then refers to the relevant ring segment of the stator disk.

A stator disk can generally preferably be produced from sheet metal, in particular by means of stamping and / or bending. In general, a stator disk can be composed, for example, of at least two partial rings, in particular half-rings.

It goes without saying that the turbomolecular pumps and manufacturing processes described here can advantageously be developed individually and in combination by means of the embodiments and individual features of the respective other turbomolecular pumps or manufacturing processes described here.

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 spanend aus Vollmaterial hergestellte Statorschaufel des Standes der Technik im Querschnitt mit Schnittebene quer zur Erstreckungsrichtung der Statorschaufel,

Fig. 7

eine aus Blech hergestellte Statorschaufel des Standes der Technik im Querschnitt,

Fig. 8

eine aus Blech hergestellte Statorschaufel im Querschnitt mit Kennzeichnung von überschüssigem Material,

Fig. 9

die Statorschaufel der Fig. 8 nach einem Abplatten,

Fig. 10

eine Statorscheibe des Standes der Technik in einer stark vereinfachten Seitenansicht,

Fig. 11

eine Statorscheibe mit außermittig in Bezug auf die Statorschaufeln angeordnetem Bund in einer derjenigen der Fig. 10 entsprechenden Ansicht.

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 bottom 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 state-of-the-art stator blade made of solid material in cross section with a cutting plane transverse to the direction of extent of the stator blade,

Fig. 7

a stator vane made of sheet metal of the prior art in cross section,

Fig. 8

a stator blade made of sheet metal in cross section with marking of excess material,

Fig. 9

the stator vane of the Fig. 8 after a flattening,

Fig. 10

a stator disk of the prior art in a greatly simplified side view,

Fig. 11

a stator disk with a collar arranged eccentrically with respect to the stator blades in one of those of FIG Fig. 10 corresponding view.

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 ). Several 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 turbomolecular 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 there is also a sealing gas connection 135, which is also referred to as a purging gas connection, via which purging 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 each other. 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 attached 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. It there are other turbomolecular 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, forming a radial Holweck gap 171 and with this forms the first Holweck pumping stage following the turbo molecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 is opposite 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 pump stage. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165 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 with the radially inner Holweck gap 175 is connected. 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 167, 169 each have a plurality of Holweck grooves running helically around the axis of rotation 151 in the axial direction, while the opposing 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 store. 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 storage comprises a plurality of absorbent disks 187 stacked on top of one another, which are provided with 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 stripper to the rotating injection nut 185 and as a result of the centrifugal force along the injection nut 185 in In the direction of the increasing outer diameter of the injection nut 185 to the roller bearing 181, where it fulfills a lubricating function, for example. 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 idle during normal operation of the vacuum pump 111 without contact and only when the rotor 149 is excessively deflected radially relative to the stator comes into engagement to form a radial stop for the rotor 149, so that a collision of the rotor-side structures with the stator-side structures is prevented. 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 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 in 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 labyrinth seal 223, known per se, can also be provided between the rotor hub 161 and a wall 221 delimiting the engine compartment 137, in particular in order to achieve a better sealing of the motor compartment 217 from the Holweck pump stages located radially outside.

The Figures 6 to 11 show stator blades or stator disks in a highly schematic representation. The stator disks 157 of the turbo molecular pump 111 of FIG Figs. 1 to 5 can be designed according to the invention, ie the invention can be used in a turbo-molecular pump, as it is based on Figs. 1 to 5 has been described.

The Figures 6 and 7 serve to illustrate the state of the art. Both show a stator blade 20 in a cross section, namely with a sectional plane transverse to a direction of extent of the stator blade. This direction of extension runs radially in the pump with respect to the axis of rotation of the rotor. The axis of rotation of the rotor is in the Figures 6 to 11 indicated by the dashed line 21. The cutting plane of the cross section shown here thus runs parallel to the axis of rotation 21 of the rotor, not shown here, which runs vertically here and in the other figures. Consequently, the blades 20 are inclined with respect to a plane (not shown) which runs perpendicular to the axis of rotation 21 and which runs horizontally in the cross section shown. You look into the Figures 6 and 7 (and also in the Figures 8 and 9 ) In particular, in each case on the radially outwardly pointing cut surface of the blade 20, which is inclined with respect to the horizontal. In other words, this applies to all of them Figures 6 to 11 one looks, so to speak, in the radial direction along the flat sides of a respective blade 20, wherein Figures 10 and 11 are simplified in particular in that they show a development with respect to the axis of rotation 21 of the rotor.

Often the stator disks in turbo molecular pumps are milled from the solid. The stator blade 20 of the Fig. 6 is machined, for example by milling and / or sawing. Typically, a flat disk made of solid material is sawn or milled radially in such a way that the several blades remain. As a result of this manufacturing process, the stator blade 20 has flat ends 22 and 24 which run perpendicular to the axis of rotation 21 and thus horizontally and are axial with respect to the axis of rotation 21. These result in particular from the usually flat end faces of the disk before the milling or sawing process.

For reasons of cost, it can be advantageous to manufacture the stator disks from sheet metal in a stamping process. Fig. 7 illustrates a known stator blade 20 made of sheet metal, which is typically first formed from a flat sheet metal by punching and then brought into the oblique orientation shown here by bending. In particular, from this manufacturing method it results that the ends 22 and 24 which are axial with respect to the axis of rotation 21 are not flat, as is the case with the stator blade 20 of FIG Fig. 6 is the case, but essentially angular. The stator blade 20 of the Fig. 7 namely, in particular has a substantially rectangular cross section, the corners of the rectangle forming the axial ends 22, 24 of the stator blade 20.

Consequently, the cross-sectional shape of the individual blades differs depending on the manufacturing process: The milled or sawn blade 20 of the Fig. 6 is parallelogram-shaped in cross-section. The stamped from sheet metal blade 20 of the Fig. 7 is rectangular in cross section.

Due to the different cross-sectional shapes, the blade 20 has Fig. 7 a larger axial installation space with the same pumping effect than that of the Fig. 6 . In other words, with the same axial gaps or with the same axial gaps Overall height the effective pump height of the blade 20 or the stator disk of the Fig. 7 smaller.

In particular, if the aim is to replace stator disks in existing pumps, that is to say to improve existing pump designs in accordance with the object of the invention, only a certain amount of space is available axially. The ultimate goal is to change the contour of the stator blade made of sheet metal so that it is as close as possible to the milled contour - especially as in Fig. 6 - comes up.

For example, by means of a further forming step, in particular in the punching process, the material triangle of the rectangular cross-section protruding from the axial end (in particular irrelevant in terms of vacuum technology) is flattened so that the blade contour now approximates the parallelogram shape. As a result, less installation space is wasted axially without impairing the pumping effect. This is illustrated in more detail below.

In Fig. 8 is a further stator vane 20 with a rectangular cross-section compared to FIG Fig. 7 shown enlarged. The axial end 22 can preferably be an upstream end and the axial end 24 can be a downstream end of the stator blade 20.

A region 26 of the illustrated cross section is marked which is essentially triangular. The material of the stator blade 20 in this area 26 is largely irrelevant for the pumping action of the stator blade 20 or the stator disk, that is to say superfluous. For clarity, the pumping direction 28 is marked here by an arrow. The pumping direction 28 runs in particular parallel to the axis of rotation 21 of the rotor, not shown here.

Rather, what is decisive for the pumping effect is the flat side 30 of the stator blade 20 on the downstream side and here the lower one. As for example in FIG Fig. 8 As can be seen, the region 26 thus takes up axial installation space without developing an active pumping effect.

The stator blade 20 of the Fig. 9 therefore has a flattening 32 according to the invention at the axial end 22. As a result of this, the area 26 with excess material is significantly smaller and, in particular, the overall axial height of the stator blade 20 and of the relevant stator disk is reduced.

The flattening 32 is embodied here as an at least essentially flat surface in relation to the three-dimensional extension of the stator blade 20. In particular, the flattening 32 or the surface runs over the entire radial extent, that is to say over the entire radial length, of the stator blade 20. In this embodiment, the surface of the flattening 32 runs perpendicular to the axis of rotation 21 of the rotor of the turbo-molecular pump. The axial gain in installation space corresponds to the axial distance between the surface and the upper tip of the triangle in Fig. 8 , When it is in Fig. 9 is projected. This triangle is in Fig. 9 indicated by dashed lines and its upstream tip is denoted by 22 '.

The flattening 32 can be produced in different ways. For example, the axial end 22 can be ground off. In Fig. 9 the stator vane 20 is illustrated as one that is flattened not by grinding, but rather by forming, namely extrusion. A deformation force was in particular essentially perpendicular to the disk plane or parallel to the axis of rotation 21 of the rotor, in Fig. 9 from top to bottom, applied. The material of the area 26 or of the stator blade 20 is reshaped in such a way that it extends in an area that extends over the in Fig. 8 Area 26 marked as a triangle goes out laterally, namely laterally next to the flattened area 32 in such a way that the axial overall height of the stator blade 20 is in spite of this resulting bead 34 is not enlarged. During the deformation process, the stator blade 20 was preferably supported flat on the flat side 30.

The bead 34 is arranged on a flat side 36, which here is the upstream flat side and which points in the same axial direction as the end 22. In addition, the bead 34 is arranged directly adjacent to the flattening 32.

The bead 34 is arranged at least essentially in such a way that it does not influence the pumping action of the stator blade 20. This is because the pumping effect is essentially determined by the flat side 30 on the downstream side. However, a comparison shows that in Fig. 9 the area 26 with excess material is axially significantly smaller than that of the Fig. 8 . Thus, the flattening 32 allows the axial installation space of the stator blade 20 or of the stator disk to be reduced in a simple manner, to be precise without any negative effects on the pump performance.

When the stator blade 20 of the Fig. 9 the excess material or that of the area 26 is ultimately pressed into an area where it no longer interferes, namely not interfering with the axial installation space and the pumping effect. The material is preferably pressed against the fluidic rear side, as here against the flat side 36, where it no longer interferes. The gain from the flattening is greater, the flatter the blade angle. At blade angles of approx. 10 °, as can be provided for example in the fore-vacuum area, the excess or disturbing triangle can make up to 1/3 of the total height.

It is understood that in particular in the Figures 8 and 9 the proportions of the stator blades 20 are not true to scale, but are adapted for the purpose of illustration. In particular, the length of the rectangular cross-section is in an actual stator blade 20, that is to say the width of the flat sides 30 and 36, is significantly larger in relation to the flattening than shown.

In principle, the downstream end 24 can also have a flattening, but this is not shown. In this respect, it is also possible to press away the interfering triangle on the underside of the disk or blade 20.

In Fig. 10 a stator disk 38 is shown in simplified form, which comprises a collar 40 and a plurality of stator blades 20 connected to the collar 40. The collar 40 can be an inner and / or outer collar, for example.

The collar 40 is arranged axially centrally with respect to the stator blades 20, as is customary in the prior art.

Fig. 11 illustrates a stator disk 38 according to the invention, in which the collar 40 is arranged axially eccentrically with respect to the stator blades 20. With respect to a pumping direction 28 shown in Fig. 11 runs from top to bottom by way of example, the collar 40 is arranged as a whole and with its axial center towards or downstream of the axial center of the stator blade. A connection point between the collar 40 and the stator blade 20 is located at the axial height of the collar 40 and is thus also arranged after the axial center of the stator blade 20.

The blade plane, that is to say the plane of the axial blade center points, is consequently not positioned centrally with respect to the collar 40, but is axially displaced and thus asymmetrical. This makes it easier to remove the disk 38 again during dismantling, since the probability of a collision of the in Fig. 11 lower blade sections is reduced with other components.

The stator disks 38 of the Figures 10 and 11 can for example be made of sheet metal and are shown here with pointed axial ends 22 and 24, similar to FIG Figures 7 and 8 . In the Figures 10 and 11 the axial direction or the axis of rotation 21 again runs vertically, as in FIG Figures 6 to 9 . Consequently, here too the blades 20 are inclined with respect to a disk plane (not shown) running perpendicular to the axis of rotation 21, in which the collar 40 lies and which consequently runs horizontally. One looks in Figures 10 and 11 - different than in the Figures 6 to 9 - Not on a cut surface of the blades 20, but on the radially outwardly facing side of the collar 40, if this is an outer collar.

It goes without saying that the axial ends 22 and / or 24 can also have a flattening, for example such as in FIG Fig. 9 shown, in particular to save axial space.

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

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 Catch camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

20th

Stator blade

21st

Axis of rotation

22nd

axial end

24

axial end

26th

Area

28

Pumping direction

30th

Flat side

32

Flattening

34

bead

36

Flat side

38

Stator disc

40

Federation

Claims (15)

A turbo molecular pump (111) comprising: a rotor (149) with a plurality of rotor blades distributed over its circumference, which rotor blades can be driven to rotate about an axis of rotation (21, 151) in order to generate a pumping effect, and at least one stator disk (38, 157), which has a plurality of stator blades (20) distributed over its circumference and with which the rotor (149) cooperates to generate the pumping action, wherein the stator blades (20) of the stator disk (38, 157) are oriented obliquely with respect to a disk plane which runs perpendicular to the axis of rotation (21, 151) of the rotor (149), wherein the stator disk (38, 157) is made of sheet metal, and wherein at least one stator blade (20) has a flattening (32) at at least one axial end (22, 24). Turbo molecular pump (111) according to claim 1,
wherein the flattening (32) comprises an at least substantially flat surface. Turbo molecular pump (111) according to Claim 1 or 2,
wherein the surface runs at least substantially parallel to the plane of the disk. Turbomolecular pump (111) according to at least one of the preceding claims,
wherein the flattening (32) extends over the entire length of the stator blade (20). Turbomolecular pump (111) according to at least one of the preceding claims,
wherein the axial end is an upstream end (22) or a downstream end (24) of the stator blade (20), or wherein both an upstream end (22) and a downstream end (24) of the stator blade (20) have a flattening (32 ) exhibit. Turbomolecular pump (111) according to at least one of the preceding claims,
wherein all of the stator blades (20) of the stator disk (38, 157) have at least one flattening (32). Method for producing a stator disk (38, 157) with a plurality of stator blades (20) distributed over its circumference for a turbo molecular pump (111), in particular one according to one of the preceding claims;
wherein the stator disc (38, 157) is made of sheet metal,
wherein the stator blades (20) of the stator disk (38, 157) are aligned obliquely with respect to a plane of extension of the sheet metal, and
wherein at least one stator blade (20) is flattened at at least one end (22, 24) with respect to a normal to the plane of extension of the sheet metal. Method according to claim 7,
wherein the flattening comprises reshaping, in particular pressing. Method according to claim 7 or 8,
wherein the stator vane (20) has a first flat side (36) facing in the same direction with respect to the normal as the flattened end (22), and wherein the flattening comprises that a material of the stator vane (20) in the direction of the first flat side (36) is moved. Method according to at least one of claims 7 to 9,
wherein the stator blades (20) are formed by punching and / or aligned obliquely by bending, and wherein the flattening is an additional method step or part of an additional method step. Turbomolecular pump (111), in particular according to one of Claims 1 to 6 and / or with a stator disk, which is or can be produced by a method according to one of Claims 7 to 10, comprising: a rotor (149) with a plurality of rotor blades distributed over its circumference, which rotor blades can be driven to rotate about an axis of rotation (21, 151) in order to generate a pumping effect, and at least one stator disk (38, 157), which has a plurality of stator blades (20) distributed over its circumference and with which the rotor (149) cooperates to generate the pumping action, wherein the stator blades (20) of the stator disk (38, 157) are oriented obliquely with respect to a disk plane which runs perpendicular to the axis of rotation (21, 151) of the rotor (149), the stator blades (20) being carried by at least one collar (40), in particular an inner and / or outer collar, wherein the collar (40) is arranged axially eccentrically with respect to at least one stator blade (20), in particular to all stator blades (20) of the stator disk (38, 157). Turbo molecular pump (111) according to claim 11,
wherein the collar (40), a connection point between the collar (40) and the respective stator blade (20) and / or an axial center of the collar (40) before or after the axial center of the stator blade (20) in relation to a pumping direction (28) are arranged. Turbomolecular pump (111) according to claim 11 or 12,
wherein an outer and an inner collar (40) of the stator disk (38, 157) are arranged at the same or different axial height. Turbomolecular pump (111) according to at least one of claims 11 to 13,
wherein the collar (40), in particular an entire inner and / or outer collar, is arranged eccentrically with respect to several, in particular all, stator blades (20). Turbomolecular pump (111) according to at least one of claims 11 to 14,
wherein the collar (40) is formed continuously ring-shaped or with several ring segments.

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