EP3608545A1 - Vacuum pump - Google Patents

Abstract

The invention relates to a vacuum pump with a stator with a plurality of stator disks which follow one another in the direction of an axis of rotation, each having a pump-active structure, and with a rotor which is rotatably mounted about the axis of rotation relative to the stator and which has a rotor shaft and a plurality of axially arranged on the rotor shaft Comes in the direction of successive rotor disks arranged between the stator disks, each having a pump-active structure, at least one rotor disk and / or at least one rotor disk delimiting a radial sealing gap formed between the rotor disk and the stator, and wherein the sealing gap extends at least in sections obliquely to the axis of rotation.

Description

The present invention relates to a vacuum pump, in particular a turbomolecular pump.

Vacuum pumps such as Turbomolecular pumps are used in different areas of technology in order to create a vacuum necessary for a particular process. Turbomolecular pumps comprise a stator with a plurality of stator disks which follow one another in the direction of an axis of rotation, each of which has a pump-active structure, and a rotor which is rotatably mounted about the axis of rotation relative to the stator and which has a rotor shaft and a plurality of axially arranged and on the rotor shaft which are arranged successively in the axial direction and between them Stator disks arranged rotor disks each having a pump-active structure.

Due to its design, such a vacuum pump has dynamic sealing areas, for example sealing gaps between the radial outer ends of the rotor disks and the stator or between the radial inner ends of the stator disks and the rotor, which, because of their inadequate tightness, enable undesired backflow of the gas against the direction of flow , which reduces the suction power and the compression of the vacuum pump. A reduction in the gap widths of existing sealing gaps to reduce the backflow is only possible to a limited extent, since if the gap widths are too small, there is a risk of a collision between the rotor and the stator during operation of the vacuum pump and the effort required to manufacture the vacuum pump as a result of the higher demands on the Component tolerances are increasing.

Out DE 20 2010 011 796 U1 A turbomolecular pump is known in which a diaphragm element is provided between at least one stator element and at least one adjacent rotor element to reduce the gas backflow, which is formed in one piece with the stator element and is arranged between the stator element and the rotor element following the stator element in the conveying direction. This is intended to reduce backflow through the radial sealing gap formed between the radial outside of the upstream rotor element and the stator. The gas is to be deflected inward in the radial direction by the diaphragm element, so that it cannot pass through the radially outer sealing gap between the upstream rotor element and the stator.

A backflow nevertheless takes place through this sealing gap, since the gas flowing back flows on the way through the stator disk in a radial direction to the outside and can thus reach the area of the radial sealing gap of the upstream rotor disk. In addition, the diaphragm elements increase the axial overall height of the vacuum pump and must be provided as additional elements and attached to the stator elements, which increases the effort for the provision of the vacuum pump.

The object of the invention is therefore to provide a vacuum pump which has improved pump performance, in particular a high pumping speed and a high compression, and can be provided with little effort.

The object is achieved by a vacuum pump with the features of claim 1.

The vacuum pump, which is in particular a turbomolecular pump, comprises a stator with a plurality of stator disks which follow one another in the direction of an axis of rotation, each of which has a pump-active structure, and a rotor which is rotatably mounted about the axis of rotation relative to the stator and which has one rotor shaft and a plurality arranged on the rotor shaft , Comprising in the axial direction successive and arranged between the stator disks, each having a pump-active structure. At least one rotor disk delimits a radial sealing gap formed between the rotor disk and the stator. At least one stator-side sealing section is provided, which at least partially covers the sealing gap when viewed in the axial direction against the conveying direction and is arranged in relation to the conveying direction before and / or next to the pump-active structure of the stator disk following the rotor disk in the conveying direction.

The sealing section covers the sealing gap in the axial direction and thus represents an obstacle to axial backflow of the gas passing through the sealing gap. Since the sealing section is arranged in front of and / or next to the pump-active structure of the downstream stator disk, the sealing section prevents it that in the region of the pump-active structure of the stator disk, the back-flowing gas on its way back through the stator disk flows in the radial direction towards the sealing gap of the upstream rotor disk and consequently can pass into the sealing gap after passing through the stator disk and can flow back through the sealing gap. Instead, the gas can flow back through the stator disk at most in a region distant from the sealing gap and is therefore, after any backflow through the stator disk, detected by the pump-active structure of the upstream rotor disk, which redirects the gas in the conveying direction again. The sealing section thus reduces the backflow and increases the pump performance.

Advantageous embodiments of the invention are described in the subclaims, the description and the figures.

According to an advantageous embodiment, the sealing section covers the sealing gap over its entire radial gap width. This achieves a particularly effective seal, which ensures high pumping speed and high compression of the vacuum pump. The rotor disk can engage behind the sealing section in the radial direction, in particular to ensure that the sealing gap is covered by the sealing section over the entire gap width of the sealing gap.

The sealing section is preferably annular. The sealing section can cover the sealing gap over at least approximately the entire circumference of the rotor disk.

According to an advantageous embodiment, the stator disk has a ring, in particular an outer ring, which carries the pump-active structure of the stator disk, the sealing section being formed by the ring of the stator disk. By designing a ring of the stator disk carrying the pump-active structure as a sealing section, an additional outlay for the provision of the sealing section and an additional space requirement for the sealing section are largely avoided. To form the sealing section, for example, a stator disk with an outer ring can easily be used, which has a relatively large radial width and covers the radial sealing gap of the preceding rotor disk.

A further embodiment provides that the sealing section is formed by a spacer ring, which holds two stator disks successively in the axial direction at an axial distance from one another. Such spacer rings are cheap anyway, by a predetermined axial distance between the stator disks maintain, and can be easily modified so that they form a sealing portion for covering the radial sealing gap of the upstream rotor disk. The radial sealing gap can be delimited by a section of the spacer ring and the sealing section can be formed by a section of the spacer ring that protrudes in the radial direction relative to the section of the spacer ring that delimits the sealing gap and in particular forms a shoulder of the spacer ring.

The formation of the sealing section by means of a spacer ring is particularly advantageous if the stator disk following the rotor disk in the conveying direction does not have a ring arranged in the area of the sealing gap, that is to say, for example, no outer ring. Such a stator disc can, for example, be machined from a solid body by material removal, while a stator disc with an outer ring e.g. can be designed as a laminated stator disk, i.e. as a stator disk, which is produced by deforming a base body formed by a sheet metal.

According to an advantageous embodiment, the sealing section of the spacer ring delimits a groove which extends into the spacer ring in the radial direction. The rotor disk can engage in the groove, preferably in the radial direction. The radial sealing gap can be limited by the rotor disk and by the groove base. The side walls of the groove preferably cover the sealing gap in the axial direction. This embodiment has the advantage that the sealing gap is covered not only on one side but also on both sides, that is to say both in the downstream direction and in the upstream direction, in each case by a side wall of the groove. The side walls of the groove can each delimit one of two axial sealing gaps adjoining the radial sealing gap on both sides. A particularly effective sealing of the radial sealing gap is thereby achieved.

According to an advantageous embodiment, the spacer ring is divided in the radial direction in such a way that the spacer ring and the rotor disk can be assembled in the axial direction. This is particularly advantageous if the spacer ring, as described above, has a radial groove in which the rotor disk engages radially. In this case, the spacer ring can be divided in the radial direction in the region of the groove in order to enable axial assembly. The possibility of axial assembly considerably reduces the effort required to manufacture the vacuum pump.

According to a preferred embodiment, the rotor disk has at least one radial extension which preferably projects in the radial direction from the pump-active structure of the rotor disk, the radial sealing gap being delimited at least in sections by the extension. Such an extension can be adapted to ensure a particularly good seal of the sealing gap, so that a backflow is avoided particularly reliably. The extension is preferably gas-tight throughout to ensure the best possible seal. It is preferred if the rotor disk engages with the extension in a radial groove of a spacer ring as described above. For example, the extension can be ring-shaped and / or extend over at least approximately the entire circumference of the rotor disk. The pump-active structure can have a plurality of pump-active elements, in particular blades, wherein a radial extension, in particular extending over the entire circumference of the rotor disk, can be carried by a plurality of pump-active elements and / or a plurality of separate radial extensions of the type described, which can be provided by different pump-active elements stand out. The radial extension can also be designed as a radial extension of the blades in the region of the groove.

The extension preferably extends only over part of the axial extent of the pump-active structure of the rotor disk. This can result in additional material costs and the additional weight of the rotor disk formed by the extension can be kept low and nevertheless a targeted and extremely effective sealing of the sealing gap can be achieved. If, as described above, the sealing section is formed by a spacer ring with a groove into which the extension engages, the groove preferably also extends only over part of the axial extent of the pump-active elements of the rotor disk. It can thereby be achieved that the groove walls closely surround the extension on all sides, so that the radial sealing gap is preferably only accessible via axial gaps, as a result of which the backflow is further reduced.

Another object of the invention is a vacuum pump with the features of claim 8.

The vacuum pump comprises a stator with a plurality of stator disks which follow one another in the direction of an axis of rotation, each of which has a pump-active structure, and a rotor which is rotatably mounted relative to the stator about the axis of rotation and which has a rotor shaft and a plurality of axially arranged and on the rotor shaft which are arranged one after the other in the axial direction comprises rotor disks arranged in the stator disks, each having a pump-active structure. At least one stator disk and / or at least one rotor disk delimits a radial sealing gap formed between the stator and the rotor. The sealing gap extends at least in sections at an angle to the axis of rotation.

The fact that the sealing gap extends at least in sections and in particular over its entire length obliquely to the axis of rotation increases the length of the sealing gap and improves its tightness. As explained in detail below, such an oblique sealing gap can also be realized particularly easily, for example by the sealing gap being delimited, at least in sections, by a foot section or collar section of the rotor disk, which runs obliquely to the axis of rotation. The oblique sealing gap or one or each oblique section of the sealing gap can have a straight or curved shape or extend in a step-like manner in a direction oblique to the axis of rotation.

Surfaces delimiting the sealing gap lie opposite one another in the radial direction and are preferably at least approximately parallel to one another. The gap preferably has an at least approximately constant gap width.

Advantageous embodiments of the vacuum pump according to claim 8 are described below. This vacuum pump can also be designed as a vacuum pump according to claim 1. The advantages and advantageous embodiments described herein in relation to the vacuum pump according to claim 1 are accordingly also advantages and advantageous embodiments of the vacuum pump according to claim 8.

The vacuum pump is preferably a turbomolecular pump. The vacuum pump can also be a side channel pump.

According to an advantageous embodiment, a stator disc delimiting the sealing gap and / or a rotor disc delimiting the sealing gap has a ring, in particular an inner ring, which carries the pump-active structure of the respective disc, at least a portion of the sealing gap which runs obliquely to the axis of rotation, is limited by the ring of the stator disk and / or is limited by the ring of the rotor disk. As a result, a sealing gap with advantageous properties can be created without additional elements. The ring of the rotor disk is preferably arranged on the rotor shaft in order to connect the rotor disk to the rotor shaft.

According to one embodiment, a ring of the rotor disk, in particular an inner ring, which delimits the sealing gap has a collar section which projects in the axial direction, at least a section of the sealing gap which runs obliquely to the axis of rotation being delimited by the collar section. The collar section is preferably connected to the rotor shaft and can therefore also serve, within the scope of the invention, to connect the rotor disk to the rotor shaft and to create the sealing gap which is oblique to the axis of rotation.

The collar section can either be formed in one piece with the shaft or can be designed as a separate part and connected to the shaft.

The collar section can have a shape that widens in the radial direction toward the rotor shaft, as a result of which a mechanically particularly good connection of the rotor disk to the rotor shaft can be created. A surface of the collar section that is present in the area of the widening can serve to limit at least one section of the sealing gap that is oblique to the axis of rotation. The oblique section of the sealing gap can run in the axial direction from the rotor disk to the stator disk in the radial direction towards the rotor shaft. Because the gap between the widening collar section and the stator is designed as an oblique sealing gap or sealing gap section, a good sealing effect is achieved in this area and the problem is avoided that the widening shape of the collar section creates an extensive gap between the rotor and the stator, which allows excessive backflow.

According to an advantageous embodiment, a ring delimiting the sealing gap, in particular the stator disk, has an extension projecting in the radial direction, at least a section of the sealing gap which extends obliquely to the axis of rotation being delimited by the extension. An extension of the stator disk preferably delimits the inclined section of the sealing gap together with a collar section of the rotor disk as described above. As described above, the configuration of the intermediate space between the collar section and the stator as a sealing gap or sealing gap section prevents a high backflow in the region of the widening collar section. The stator disk with the ring and the extension is preferably formed in one piece by a single body.

According to an advantageous embodiment, the sealing gap has at least two sections which run obliquely to the axis of rotation and at an angle to one another, preferably both sections being delimited in each case by a stator disk on the one hand and in each case one of two rotor disks adjacent to the stator disk on the other. The two sections can form a V-shaped sealing gap. Both sections can be delimited by a radially protruding extension of the stator disk on the one hand and a collar section of the respective rotor disk on the other hand. The two sections of the sealing gap can run in the axial direction from the respective rotor disk to the stator disk in the radial direction inwards, or the apex of the V-shape of the sealing gap can point towards the rotor shaft.

Another object of the invention is a vacuum pump with the features of claim 13.

The vacuum pump comprises a stator with a plurality of stator disks which follow one another in the direction of an axis of rotation, each of which has a pump-active structure, and a rotor which is rotatably mounted relative to the stator about the axis of rotation and which has a rotor shaft and a plurality of axially arranged and arranged on the rotor shaft, which are successive in the axial direction comprises rotor disks arranged in the stator disks, each having a pump-active structure. The pump-active structures of the stator disks and rotor disks are designed to provide a pumping action oriented in a conveying direction for a gas present in a scooping area. There is a sealing area adjacent to the scoop area, which is at least partially delimited by a stator disk and a rotor disk adjacent to the stator disk. Opposing and delimiting the sealing area surfaces of the rotor and the stator form at least one pump stage for providing a pumping action for the gas present in the sealing area, which counteracts a backflow of the gas through the sealing area.

In the context of the present description, the scoop area is generally understood to mean the area in which the pump-active structures of the stator disks and rotor disks provide a pumping action oriented in a conveying direction for the gas present there. A sealing area is understood to mean an area which adjoins the scooping area and through which, in principle, a backflow of the gas directed against the conveying direction can take place.

Because opposing surfaces of the rotor and the stator delimiting the sealing area form at least one pump stage for providing a pumping action for the gas present in the sealing area, which counteracts a backflow of the gas through the sealing area, the backflow is reduced and the pumping capacity of the vacuum pump improved.

In a possible development, it is provided that at least one of the surfaces forming the pump stage runs obliquely to the axis of rotation.

Advantageous embodiments of the vacuum pump according to claim 13 are described below. This vacuum pump can simultaneously be designed as a vacuum pump according to claim 1 and / or as a vacuum pump according to claim 8. The advantages and advantageous embodiments described herein in relation to the vacuum pumps according to claim 1 and claim 8 are accordingly also advantages and advantageous embodiments of the vacuum pump according to claim 13.

The vacuum pump is preferably a turbomolecular pump. The vacuum pump can also be a side channel pump.

The surfaces forming the pump stage are preferably formed by the stator disk and the adjacent rotor disk. The pump stage can thus be implemented simply by correspondingly adapting the surfaces of the stator disk and the rotor disk.

According to an advantageous embodiment, the stator disk has a ring, in particular an inner ring, which bears the pump-active structure of the stator disk, and the rotor disk has a ring, in particular an inner ring, which bears the pump-active structure of the rotor disk, which form the pump stage Surfaces are formed by the rings of the stator disk and the rotor disk. These surfaces are particularly suitable for realizing a pump stage that reduces the backflow.

The surfaces forming the pump stage preferably lie opposite one another in the axial direction. The surfaces can limit an axial sealing gap, which is part of the sealing area.

The sealing area can comprise a radial sealing gap between the rotor and the stator and two axial sealing gaps adjoining the radial sealing gap on both sides. The axial sealing gaps are preferably delimited by the same stator or rotor disk and in each case one of two rotor or stator disks adjacent to the stator or rotor disk or by rings of the stator and rotor disks which carry the pump-active structures of the stator and rotor disks. Two pump stages are preferably provided, each of which is formed by the surfaces which delimit one of the axial sealing gaps and which counteract a backflow.

The pump stage is preferably a Siegbahn pump stage. Such a pump stage is simple to implement and effectively counteracts a backflow. For example, one of the surfaces forming the pump stage can be smooth and the opposite surface can have at least one helical or helical groove in which the pumped gas is guided. Several and in particular two Siegbahn pump stages can also be provided, which, as described above, are each assigned to an axial sealing gap of the sealing area.

Advantages and advantageous embodiments of all vacuum pumps described in the present description are described below.

In all pumps of the present description, the rotor disks and the stator disks are preferably arranged alternately in the axial direction.

The rotor can be formed in one part or in several parts. In the case of a multi-part rotor, the rotor shaft on the one hand and the rotor disks connected to the rotor shaft on the other hand can be designed as separate parts. The stator can also be constructed in several parts. In particular, the stator can be a housing, a plurality of parts connected to the housing and separated from the housing trained rotor disks and preferably have a plurality of spacer rings connected to the housing and formed as parts separate from the housing and the rotor disks.

The stator disks, rotor disks and / or spacer rings can each have an essentially circular basic shape and / or can be formed in one part or in several parts. A multi-part stator or rotor disk or a multi-part spacer ring can in particular comprise several and in particular two part-circular parts which together form the respective disk or the spacer ring.

The vacuum pump can be designed as a turbomolecular pump. The stator disks and rotor disks can accordingly be designed as turbomolecular stator and rotor disks with a turbomolecular pump-active structure. The pump-active structures of the rotor disks and the stator disks preferably have a plurality of pump-active elements designed as blades, which are preferably carried by an outer ring and / or by an inner ring of the respective disk. The blades can have an inclined position relative to the axial direction, which serves to deflect the gas molecules that come into contact with the blades in the conveying direction, the inclined position of the blades of the stator disks and the rotor disks preferably being mirror images of one another.

In the case of a side channel pump, the rotor disks, as a pump-active structure, preferably have rotor blades in the region of their radial outer side, which rotate in a side channel formed by the stator disks, which is widened compared to the rotor blades. The pump-active structures of the stator disks are formed by sections of the stator disks delimiting the side channel. A side channel can be separated by two successive ones in the axial direction Stator disks may be limited, between which a rotor disk with rotor blades is arranged.

In the context of the present description, a gap or sealing gap is understood to mean an intermediate space which is narrow in a predetermined direction and has a greater extent in the other directions. A gap or sealing gap can in principle have an at least approximately constant gap width within the scope of the invention.

Fig. 1

eine Vakuumpumpe gemäß einer Ausführungsform der Erfindung in einer geschnittenen Darstellung,

Fig. 2

den Bereich A der in Fig. 1 gezeigten Vakuumpumpe,

Fig. 3

eine Statorscheibe der in Fig. 1 gezeigten Vakuumpumpe in Draufsicht in einem unfertigen Herstellungszustand,

Fig. 4

einen Ausschnitt der in Fig. 3 gezeigten Statorscheibe,

Fig. 5

die in Fig. 3 und 4 gezeigte Statorscheibe im fertigen Zustand in perspektivischer Darstellung,

Fig. 6

den Bereich B der in Fig. 1 gezeigten Vakuumpumpe,

Fig. 7

den Bereich C der in Fig. 1 gezeigten Vakuumpumpe,

Fig. 8

einen Ausschnitt einer Vakuumpumpe gemäß einer weiteren Ausführungsform der Erfindung in einer geschnittenen Darstellung, und

Fig. 9

den Bereich D der in Fig. 7 gezeigten Vakuumpumpe.

The invention is described below by way of example using advantageous embodiments with reference to the accompanying figures. Show it:

Fig. 1

a vacuum pump according to an embodiment of the invention in a sectional view,

Fig. 2

area A of in Fig. 1 shown vacuum pump,

Fig. 3

a stator disk of the in Fig. 1 shown vacuum pump in top view in an unfinished state of manufacture,

Fig. 4

a section of the in Fig. 3 stator disc shown,

Fig. 5

in the Fig. 3 and 4 shown stator disk in the finished state in a perspective view,

Fig. 6

area B of the in Fig. 1 shown vacuum pump,

Fig. 7

the area C of the in Fig. 1 shown vacuum pump,

Fig. 8

a section of a vacuum pump according to another embodiment of the invention in a sectional view, and

Fig. 9

the area D of the in Fig. 7 shown vacuum pump.

In the Fig. 1 The vacuum pump shown comprises a pump inlet 70 surrounded by an inlet flange 68 and a plurality of pump stages for conveying the gas present at the pump inlet 70 to an in Fig. 1 Pump outlet, not shown. The vacuum pump comprises a stator with a static housing 72 and a rotor arranged in the housing 72 with a rotor shaft 12 rotatably mounted about an axis of rotation 14.

The vacuum pump is designed as a turbomolecular pump and comprises a plurality of turbomolecular pump stages, which are connected to one another in series with effective pumping, with a plurality of turbomolecular rotor disks 16 connected to the rotor shaft 12 and a plurality of turbomolecular stator disks 26 arranged in the axial direction between the rotor disks 16 and fixed in the housing 72, by spacer rings 36 are kept at a desired axial distance from each other. The rotor disks 16 and stator disks 26 provide an axial pumping action in the scoop area 50 in the direction of the arrow 58.

The vacuum pump also comprises three Holweck pump stages, which are arranged one inside the other in the radial direction and are pump-connected in series. The rotor-side part of the Holweck pump stages comprises a rotor hub 74 connected to the rotor shaft 12 and two cylindrical jacket-shaped Holweck rotor sleeves 76, 78 fastened to and supported by the rotor hub 74, which are oriented coaxially to the axis of rotation 14 and are nested one inside the other in the radial direction. Furthermore, two cylindrical jacket-shaped Holweck stator sleeves 80, 82 are provided, which are also oriented coaxially to the axis of rotation 14 and in a radial direction Are nested in one another. The pump-active surfaces of the Holweck pump stages are each formed by the radial jacket surfaces opposite each other, forming a narrow radial Holweck gap, each of a Holweck rotor sleeve 76, 78 and a Holweck stator sleeve 80, 82. One of the pump-active surfaces is smooth in each case - in the present case that of the Holweck rotor sleeve 76 or 78 - and the opposite pump-active surface of the Holweck stator sleeve 80, 82 has a structure with grooves running helically around the axis of rotation 14 in the axial direction, in which the gas is propelled by the rotation of the rotor and thereby pumped.

The rotatable mounting of the rotor shaft 12 is effected by a roller bearing 84 in the area of the pump outlet and a permanent magnet bearing 86 in the area of the pump inlet 70.

The permanent magnet bearing 86 comprises a rotor-side bearing half 88 and a stator-side bearing half 90, each of which comprises an annular stack of a plurality of permanent magnetic rings 92, 94 stacked one on top of the other in the axial direction, the magnetic rings 92, 94 lying opposite one another to form a radial bearing gap 96.

An emergency or catch bearing 98 is provided within the magnetic bearing 86, which is designed as an unlubricated rolling bearing and runs empty without contact during normal operation of the vacuum pump and only comes into engagement with an radial radial deflection of the rotor relative to the stator in order to make a radial stop to form for the rotor, which prevents a collision of the rotor-side structures with the stator-side structures.

In the area of the roller bearing 84, a conical spray nut 100 is provided on the rotor shaft 12 with an outer diameter increasing toward the roller bearing 84, which is in sliding contact with at least one scraper of an operating medium store comprising several absorbent disks 102 soaked with an operating medium, such as a lubricant. In operation, the operating medium is transferred by capillary action from the operating medium storage via the wiper to the rotating injection nut 100 and, as a result of the centrifugal force along the injection nut 100, is conveyed in the direction of the increasing outer diameter of the injection nut 100 to the roller bearing 84, where it lubricates, for example Function fulfilled.

The vacuum pump comprises a drive motor 104 for rotatingly driving the rotor, the rotor of which is formed by the rotor shaft 12. A control unit 106 controls the motor 104.

The turbomolecular pump stages provide a pumping action in the direction of arrow 58 in the scoop area 50. Below are based on the 2 to 7 in the vacuum pump from Fig. 1 implemented measures to prevent backflow of the gas against the conveying direction are described. In principle, corresponding components are designated in all figures with the same reference symbols.

Fig. 2 shows the in Fig. 1 area designated with the reference symbol A with a rotor disk 16 and two adjacent stator disks 26 in detail.

Each rotor disk 16 has a plurality of blades 22, which run from one in Fig. 2 not shown inner ring of the rotor disc 16 are worn. A radial sealing gap 42 is formed between the outer radial ends of the blades 22 and the spacer rings 36 opposite each other in the radial direction.

The stator disk 26 has a plurality of blades 32, which are composed of an outer ring 30 and an inner ring Fig. 2 inner ring, not shown, are worn. The outer ring 30 of the stator disk 26 extends so far inward in the radial direction that it covers the sealing gap 42 of the rotor disk 16 preceding in relation to the conveying direction, viewed in the axial direction, and thus prevents backflow through the sealing gap 42. The area of the outer ring 30 covering the sealing gap 42 thus forms a sealing section 34 for the sealing gap 42. The sealing section 34 is arranged in relation to the conveying direction next to the pump-active structure of the stator disk 26 formed by the blades 32 and thus prevents that in the area of the pump-active structure Existing gas flows in the radial direction outwards to the sealing gap 42 preceding in the conveying direction and flows further back through the sealing gap 42 against the conveying direction.

Instead, the gas is deflected inward in the radial direction by the sealing section 34, so that after any backflow through the stator disk 26 it hits the pump-active structure formed by the blades 22 of the upstream rotor disk 16 and is pumped through it again in the conveying direction.

3 to 5 show the in Fig. 2 shown stator disc 26 in detail. In the present exemplary embodiment, the stator disk 26 consists of two semicircular parts 26a, 26b.

It is a laminated, that is to say a stator disk 26 produced or to be produced from a sheet-metal base body by deforming the base body. The blades 32 of the stator disk are between the inner ring 28 and the outer ring 30 of the stator disk 26 by punching and slitting the sheet-metal base body 26 formed. Fig. 3 and 4 show the stator disk 26 in an unfinished state in that the stator disk 26 is still in its undeformed flat state and the blades 32 have not yet been brought into their inclined position by bending the base body.

Fig. 5 shows the finished stator disc 26 after moving the blades 32 into their inclined position.

The outer ring 30 of the stator disk 26 with the sealing section 34 forms a continuously closed annular surface which covers the sealing gap 42 of the rotor disk 16 preceding in the conveying direction, preferably over the entire circumference of the rotor disk 16.

Fig. 6 shows the in Fig. 1 with the reference symbol B designated the area in Fig. 1 shown vacuum pump in detail. The rotor disk 16 has an extension 20 arranged at the outer radial ends of its blades 22 and projecting in the radial direction, which extends into a radial groove 38 of the spacer ring 36 which is adjacent to the rotor disk 16 in the radial direction and consists of the two parts 36a, 36b extends into it.

A radial sealing gap 44 is delimited by the extension 20 and the spacer ring 36, which is adjoined on both sides by an axial sealing gap 45 delimited by the extension 20 and the spacer ring 36. The lower part 36b of the spacer ring 36 forms a sealing section 40, which covers the radial sealing gap 44 and reduces a backflow directed through the sealing gap 42. In the present exemplary embodiment, the extension 20 is designed as a closed ring that runs around the entire circumference of the rotor disk 16 and is carried by the blades 22 of the rotor disk 16. The radial division of the spacer ring 36 into the two parts 36a, 36b makes it possible to assemble the rotor disk 26 and the spacer ring 36 in the axial direction despite the axial undercut formed by the engagement of the extension 20 in the groove 38.

Fig. 7 shows the in Fig. 1 with the reference number C designated the area in Fig. 1 shown vacuum pump in detail. The blades 22 of the rotor disks 16 and the blades 32 of the stator disk arranged between the rotor disks 16 26 provide a pumping action for a gas present in the scoop area 50 in the direction of arrow 58, while the inner ring 28 of the stator disk 26 with the inner rings 18 of the rotor disks 16 delimits a sealing area which comprises a radial sealing gap 46 and two axial sealing gaps 48.

Those opposite surfaces of the inner rings 18 of the rotor disks 16 and the inner ring 28 of the stator disk 26, which each delimit one of the axial sealing gaps 48, each form a Siegbahn pump stage, which provides a pumping action that counteracts a backflow of the gas through the sealing area. For this purpose, the surfaces of the inner ring 28 of the stator disk 26 each have a structuring with a spiral line-shaped groove 52 running in the radial direction, in which the propelled gas is guided. The opposite surfaces of the inner rings 18 of the rotor disks 16 are smooth. A backflow through the radial sealing gap 46 and the axial sealing gap 48 in the opposite direction to the pumping action of the Siegbahn pumping stages prevents the gas from flowing back past the blades 32 of the stator disk 26 through the sealing area, so that the pumping performance of the vacuum pump is improved.

Fig. 8 shows a section of a vacuum pump according to another embodiment of the invention in a sectional view. Fig. 9 shows the in Fig. 8 area designated by the reference symbol D in detail. In the 8 and 9 Apart from the special features described below, the vacuum pump shown corresponds to that in Fig. 1 described vacuum pump.

The rotor disks 16 of the in 8 and 9 The vacuum pump shown each comprise an inner ring 18 with a collar section 24 which widens in the radial direction towards the rotor shaft 12 and via which the rotor disks 16 are connected to the rotor shaft 12. The stator disk 26 has an inner ring 28 which has an extension 35 projecting in the radial direction. Together, the inner ring 28 of the stator disk 26 and the inner rings 18 of the rotor disks 16 delimit two axial sealing gaps 49. The extension 35 of the inner ring 28 of the stator disk 26 and the collar sections 24 also delimit a radial sealing gap 47, which connects the axial sealing gaps 49 and is V-shaped is formed and comprises two sections 47a, 47b inclined to the axis of rotation 14. In comparison to an embodiment which has no radial extension 35 and no radial sealing gap 46 which is delimited by the extension 35 and which instead extends obliquely to the axis of rotation 14, but instead has an extensive space between the collar portions 24 and the inner ring 28, the backflow is in the in 8 and 9 vacuum pump shown significantly reduced and the achievable pump capacity increased.

LIST OF REFERENCE NUMBERS

12

rotor shaft

14

axis of rotation

16

rotor disc

18

inner ring

20

extension

22

shovel

24

collar portion

26

stator

26a, 26b

Part of a stator disc

28

inner ring

30

outer ring

32

shovel

34

sealing portion

35

extension

36

spacer

36a, 36b

Part of a spacer ring

38

groove

40

sealing portion

42, 44, 46, 47

radial sealing gap

46a, 46b

Sealing gap section

45, 48, 49

axial sealing gap

50

adding area

52

groove

58

arrow

68

inlet flange

70

pump inlet

72

casing

74

rotor hub

76, 78

Holweck rotor sleeve

80, 82

Holweck stator

84

roller bearing

86

Permanent magnetic bearings

88

half of the bearing on the rotor side

90

stator side bearing half

92, 94

permanent magnetic ring

96

radial bearing gap

98

safety bearing

100

spray mother

102

absorbent disc

104

drive motor

106

control unit

Claims (15)

Vacuum pump, especially turbomolecular pump, - With a stator with a plurality of stator disks (26) which follow one another in the direction of an axis of rotation (14) and each have a pump-active structure (32), and - With a rotor rotatably mounted relative to the stator about the axis of rotation (14), which comprises a rotor shaft (12) and a plurality of rotor disks (16) arranged on the rotor shaft (12), arranged in the axial direction one after the other and between the stator disks (26) , each of which has a pump-active structure (22), at least one stator disk (26) and / or at least one rotor disk (16) delimiting a radial sealing gap (47) formed between the stator and the rotor, and
wherein the sealing gap (47) extends at least in sections obliquely to the axis of rotation (14). Vacuum pump according to claim 1,
characterized in that
Surfaces delimiting the sealing gap (47) lie opposite one another in the radial direction and are at least approximately parallel to one another. Vacuum pump according to claim 1 or 2,
characterized in that
the sealing gap (47) has an at least approximately constant gap width. Vacuum pump according to one of the preceding claims,
characterized in that
a stator disc (26) delimiting the sealing gap (47) and / or a rotor disc (16) delimiting the sealing gap (47) has a ring, in particular an inner ring (18, 28), which has the pump-active structure (22, 32) of the respective Disk (16, 26) carries, at least a portion (47a, 47b) of the sealing gap (47), which extends obliquely to the axis of rotation (14), is delimited by the ring (28) of the stator disk (26) and / or by the ring (18) of the rotor disc (16) is limited. Vacuum pump according to claim 4,
characterized in that
the ring (18) of the rotor disk (16) is arranged on the rotor shaft (12) in order to connect the rotor disk (16) to the rotor shaft (12). Vacuum pump according to claim 4 or 5,
characterized in that
a ring delimiting the sealing gap (47), in particular an inner ring (18), the rotor disk (16) has a collar section (24) projecting in the axial direction, at least one section (47a, 47b) of the sealing gap (47) being inclined the axis of rotation (14) runs through which the collar section (24) is limited. Vacuum pump according to claim 6,
characterized in that
the collar section (24) is connected to the rotor shaft (12). Vacuum pump according to claim 6 or 7,
characterized in that
the collar section (24) has a shape that widens in the radial direction towards the rotor shaft (12). Vacuum pump according to claim 8,
characterized in that
a surface of the collar section (24) present in the area of the widening serves to delimit at least one section of the sealing gap (47) which is inclined to the axis of rotation, the inclined section of the sealing gap (47) in particular being in the axial direction from the rotor disk (16) to the stator disk (26) seen in the radial direction towards the rotor shaft (12). Vacuum pump according to one of claims 4 to 9,
characterized in that
a ring (28) delimiting the sealing gap (47), in particular the stator disk (26), has an extension (35) projecting in the radial direction, at least one section (47a, 47b) of the sealing gap (47) being oblique to the axis of rotation (14) runs through the extension (35) is limited. Vacuum pump according to one of the preceding claims,
characterized in that
the sealing gap (47) has at least two sections (47a, 47b) which run obliquely to the axis of rotation (14) and at an angle to one another. Vacuum pump according to claim 11,
characterized in that
both sections (47a, 47b) are each delimited by a stator disk (26) on the one hand and one of two rotor disks (16) adjacent to the stator disk (26) on the other. Vacuum pump according to claim 11 or 12,
characterized in that
the two sections (47a, 47b) form a V-shaped sealing gap (47). Vacuum pump according to claim 13,
characterized in that
the apex of the V-shape of the sealing gap (47) points towards the rotor shaft (12). Vacuum pump according to one of claims 11 to 14,
characterized in that
the two sections (47a, 47b) of the sealing gap (47) run in the axial direction from the respective rotor disc (16) to the stator disc (26) in the radial direction inwards.

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