EP3032106B1 - Vacuum pump - Google Patents

Description

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

An exemplary turbomolecular vacuum pump comprises a rotor with a rotor shaft on which a plurality of rotor disks are arranged axially offset. Each rotor disk has a plurality of rotor blades arranged distributed in the circumferential direction. In addition, the exemplary turbomolecular pump comprises a stator with a plurality of stator disks, each of which comprises a plurality of stator blades arranged distributed in the circumferential direction. In this exemplary turbomolecular vacuum pump, the rotor disks and the stator disks are arranged alternately in the axial direction.

The exemplary turbomolecular pump has certain vacuum performance values, such as Pumping speed and compression ratio, which are set at a target speed of the rotor. However, customer requirements regarding vacuum performance values can vary widely. In practice, therefore, many different vacuum pump models are kept available for different requirements, or a vacuum pump is complexly adapted to special requirements or even specifically developed accordingly.

From the EP 1 850 011 A2 a vacuum pump according to the preamble of claim 1 is known.

Furthermore describes the WO 2005/033521 A1 a vacuum pump which has a second inlet or a lateral tap in the area of a helical element of a rotor.

It is an object of the invention to easily meet different requirements for a vacuum pump.

This object is achieved by a vacuum pump according to claim 1 and claim 5, and in particular in that at least one pure rotor area is provided in an axial area of the rotor, into which no lateral tap opens, in which at least two rotor sections follow one another without an intermediate stator section, or at least a pure stator area is provided, in which at least two stator sections follow one another without an intermediate rotor section. According to the invention, an axial distance is provided between the two rotor sections of the pure rotor area or between the two stator sections of the pure stator area.

In each case, one or more rotor sections and / or stator sections are therefore missing compared to the usual structure of a vacuum pump, in which the rotor and stator sections are arranged alternately in the axial direction.

In other words, according to the invention, e.g. compared to a pump structure not according to the invention, one or more stator or rotor sections are deliberately omitted.

The rotor and stator sections are, in particular, so-called rotor or stator disks, each of which has a plurality of rotor or stator blades arranged distributed in the circumferential direction and have a disk shape insofar as they have a height measured in the axial direction, which is smaller and in particular much smaller than their diameter. The rotor and stator sections are in particular stacked one above the other, alternately in the prior art, ie on a stator disk follows a rotor disc and vice versa. In contrast, in an embodiment according to the invention it can be provided that in a pure rotor area at least two rotor disks follow one another without an interposed stator disk, while in a pure stator area at least two stator disks follow one another without an interposed rotor disk.

For further clarification, an exemplary turbomolecular pump with alternately arranged rotor and stator sections is assumed, as is known per se in the prior art. This turbomolecular pump has certain vacuum performance values. If there are now demands on the turbomolecular pump which differ from the vacuum performance values of the pump, for example lower, only one or more rotor and / or stator sections are removed or omitted during assembly. As a result, the performance values of the pump that are possible within the framework of the construction of the turbomolecular pump are changed, e.g. reduced. However, this allows the requirements to be met in a very simple manner, while the pump does not have to be changed in construction. This makes it possible not only to offer a specific performance characteristic with a single pump model, but also to implement a large number of different performance characteristics with the same pump model. As a result, fewer different pump models have to be kept in stock and fewer design adaptations of the pumps to customer requirements have to be carried out, while a wide variety of customer requirements can still be served.

If a stator section in the vacuum pump also fulfills structural tasks in addition to its vacuum function, the stator section can be replaced by a replacement piece for the structural tasks, such as a spacer, in the pure rotor area. In general, and in particular regardless of the presence or absence of a replacement part, the invention is An axial distance is therefore provided between the two rotor sections of the pure rotor area.

It goes without saying that the above and the following further developments, which are only described for one or more pure rotor areas, can be used correspondingly for pure stator areas. This further improves the variety.

In one embodiment, the vacuum pump has at least one side tap. The side tap is different from an inlet and an outlet of the vacuum pump. In this embodiment, the invention can be used in a targeted manner in order to individually set the vacuum performance values of pump areas in front of and behind the tap. In particular, the achievable pressure in a chamber connected to the side tap, in which e.g. a larger amount of residual gas is permitted or desired, can be set specifically. A complex design change of the vacuum pump is not necessary.

The lateral tap can be provided in at least one area of the rotor. Alternatively or additionally, the lateral tap can be arranged between an inlet and an outlet of the vacuum pump. As an alternative or in addition, the pure rotor region can be arranged in the axial direction directly in front of or behind the side tap or close to a side tap. Alternatively, the vacuum pump can also have no side tap.

In one embodiment, a stator section is arranged in the axial direction between the first rotor section in the pumping direction and the second rotor section in the pumping direction. As a result, good vacuum performance values are still achieved, while the pump can be adapted to different requirements.

In a further embodiment, the rotor sections are each formed by a rotor disk which is produced separately from the rotor shaft and is fastened to the rotor shaft. In other words, it can be a disk rotor. Alternatively, a full rotor can be provided, in which the rotor sections are connected in one piece to the rotor shaft.

Further embodiments are specified in the dependent claims, the description and the figures.

Fig. 1

zeigt eine Turbomolekularpumpe mit einem reinen Rotorbereich und einem reinen Statorbereich.

Fig. 2

zeigt eine Turbomolekularpumpe mit einer seitlichen Anzapfung und einem reinen Rotorbereich.

Fig. 3

zeigt eine weitere Turbomolekularpumpe mit einer seitlichen Anzapfung und einem reinen Rotorbereich.

The invention is explained below by way of example only with reference to the drawing.

Fig. 1

shows a turbomolecular pump with a pure rotor area and a pure stator area.

Fig. 2

shows a turbomolecular pump with a side tap and a pure rotor area.

Fig. 3

shows another turbomolecular pump with a side tap and a pure rotor area.

In the Fig. 1 The vacuum pump shown as a turbomolecular pump 10 comprises an inlet 30 surrounded by an inlet flange 31 and a plurality of pump stages for conveying the gas present at the inlet 30 to an outlet. The outlet is in Fig. 1 not shown (see, for example, the outlet 32 of Fig. 2 pump shown). The turbomolecular pump 10 has no lateral tapping. The turbomolecular pump 10 comprises a stator with a static housing 36 and a rotor 12 arranged in the housing 36 with a rotor shaft 14 which is rotatably mounted about an axis of rotation R.

The turbomolecular pump 10 comprises a plurality of turbomolecular pump stages, which are connected to one another in series with effective pumping, with a plurality of rotor sections connected to the rotor shaft 14, designed as turbomolecular rotor disks 16, and with a plurality of stator sections arranged in the axial direction between the rotor disks 16 and fixed in the housing 36 and designed as a turbomolecular stator disks 22 by spacer rings 40 in a desired axial distance from each other. The rotor disks 16 and stator disks 22 provide an axial pumping action directed in the pumping direction P in a scoop area.

The turbomolecular pump 10 also comprises three Holweck pump stages which are arranged one inside the other in the radial direction and have a pumping effect and are connected in series with one another. The rotor-side part of the Holweck pump stages comprises two Holweck rotor sleeves 46, 48 fastened to and supported by the rotor shaft 14, which are oriented coaxially to the axis of rotation R and nested one inside the other. Furthermore, two cylindrical jacket-shaped Holweck stator sleeves 50, 52 are provided, which are also oriented coaxially to the axis of rotation R and are nested one inside the other. The pump-active surfaces of the Holweck pump stages are each formed by the radial lateral surfaces opposite one another with the formation of a narrow radial Holweck gap, namely a Holweck rotor sleeve 46, 48 and a Holweck stator sleeve 50, 52, respectively. In each case, one of the pump-active surfaces is smooth, in the present case, for example, that of the Holweck rotor sleeve 46 or 48, the opposite pump-active surface of the respective Holweck stator sleeve 50 or 52 being structured with a helix around the axis of rotation R in the axial direction has extending grooves in which the gas is propelled by the rotation of the rotor 12 and thereby pumped.

The rotatable mounting of the rotor shaft 14 is effected by a roller bearing 54 in the area of the outlet and a permanent magnet bearing 56 in the area of the inlet 30.

The permanent magnet bearing 56 comprises a rotor-side bearing half 60 and a stator-side bearing half 58, each of which comprises an annular stack of a plurality of permanent magnetic rings stacked on one another in the axial direction, wherein the magnetic rings face each other, forming a radial bearing gap.

Within the permanent magnet bearing 56, an emergency or catch bearing 62 is provided, which is designed as an unlubricated roller 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 12 with respect to the stator in order to make a radial stop to form for the rotor 12, which prevents a collision of the rotor-side structures with the stator-side structures.

In the area of the roller bearing 54, a conical injection nut 64 with an external diameter increasing towards the roller bearing 54 is provided on the rotor shaft 14, which is connected to one scraper by a plurality of devices, such as a lubricant, impregnated absorbent discs 66 comprising operating fluid storage is in sliding contact. In operation, the operating medium is transferred by capillary action from the operating medium storage via the wiper to the rotating injection nut 64 and, as a result of the centrifugal force along the injection nut 64, is conveyed in the direction of the increasing outer diameter of the injection nut 64 to the roller bearing 54, where it is e.g. fulfills a lubricating function.

The turbomolecular pump 10 comprises a drive motor 68 for rotatingly driving the rotor, the rotor of which is formed by the rotor shaft 14. A control unit (not shown) controls the drive motor 68.

The turbomolecular group 10 of the Fig. 1 comprises a pure rotor region 28 and a pure stator region 29. In the pure rotor region 28, two rotor disks 16 follow one another without an interposed stator disk 22. A stator disk 22 is therefore missing between the rotor disks 16. Two stator disks 22 without a rotor disk in between follow in the pure stator area 29 16 on top of each other. A rotor disk 16 between the stator disks 22 is accordingly missing here. The two rotor disks 16 in the pure rotor area 28 and the two stator disks 22 in the pure stator area 29 are each arranged at an axial distance from one another.

A respective stator disk 22 is designed in the form of two half rings which can be placed between the rotor disks 16 from the side, that is to say in the radial direction. The stator disks 22 are placed on the spacer rings 40 and carried by them. Individual stator disks 22 can thereby be removed or omitted particularly easily in order to adapt the turbomolecular pump 10 in terms of its vacuum performance values to specific requirements.

In Fig. 2 A further turbomolecular pump 10 is shown which, however, has a lateral tap 26. The side tap 26 is provided for connecting an additional vacuum chamber, not shown, in which a vacuum of a different quality is to be set than is the case in a chamber connected to the inlet 30. The lateral tap 26 defines a tap region 34 of the rotor 12, into which the lateral tap 26 opens. No stator disks 22 are arranged in the tapping area 34. A large axial distance is provided between the rotor disks 16, which delimit the tapping area, which essentially corresponds to the axial extent of the tapping area 34. The tapping area 34 is therefore kept free of pump-active elements.

Gas entering the pump via the side tap 26 becomes P - in in the pumping direction Fig. 2 So down - pumped on and finally arrives at an outlet 32.

Outside the tapping area 34, a pure rotor area 28 is provided in an axial area of the rotor 12, into which no lateral tapping opens. The pure rotor area 28 here comprises three successive rotor disks 16 without stator disks 22 lying between them. The pure rotor area 28 is arranged directly in front of the tapping area 34 in the pumping direction P. In addition, a stator disk 22 is arranged in the pumping direction P between the first rotor disk 16 and the second rotor disk 16. In the pump direction P directly behind the tapping area 34, the turbomolecular pump 10 has rotor disks 16 and stator disks 22 arranged alternately in the axial direction.

In Fig. 3 Another turbomolecular pump 10 is shown with a side tap. However, the side tap is not visible in the view shown. The lateral tap defines a tap area 34, in which no stator disks 22 are arranged. In the pumping direction, directly before the tapping area 34, a pure rotor area 28 is provided, in which no stator disks 22 are likewise arranged. In contrast, a stator disk 22 is arranged between the first pair of rotor disks 16 in the pumping direction. Immediately behind the tapping area 34, rotor disks 16 and stator disks 22 are provided in the alternating arrangement known per se.

LIST OF REFERENCE NUMBERS

10

Turbo molecular pump

12

rotor

14

rotor shaft

16

rotor disc

18

rotor blade

22

stator

24

stator

26

side tap

28

pure rotor area

29

pure stator area

30

inlet

31

inlet flange

32

outlet

34

tapping range

36

casing

40

spacer

46

Holweck rotor sleeve

48

Holweck rotor sleeve

50

Holweck stator

52

Holweck stator

54

roller bearing

56

Permanent magnetic bearings

58

permanent magnet bearing half on the stator side

60

rotor-side permanent magnet bearing half

62

safety bearing

64

spray mother

66

absorbent disc

68

drive motor

P

pumping direction

R

axis of rotation

Claims (9)

1. A vacuum pump (10), in particular a turbomolecular pump, comprising

   at least one rotor (12) which has a rotor shaft (14) and at least one rotor section (16) which is arranged at the rotor shaft (14) and which comprises a plurality of rotor blades (18) arranged distributed in the peripheral direction; and

   at least one stator which is associated with the rotor (12) and which has at least one stator section (22) which follows a rotor section (16) in the axial direction and which comprises a plurality of stator blades (24) arranged distributed in the peripheral direction,

   wherein at least one pure rotor region (28), in which at least two rotor sections (16) follow one another without a stator section (22) disposed therebetween, is provided in an axial region of the rotor (12) into which no lateral tap (26) opens,
   characterized in that
   an axial spacing is provided between the two rotor sections (16) of the pure rotor region (28).
2. A vacuum pump (10) in accordance with claim 1,
   characterized in that
   at least one pure stator region (29) is provided in which at least two stator sections (22) follow one another without a rotor section (16) disposed therebetween; and in that an axial spacing is provided between the two stator sections (22) of the pure stator region (29).
3. A vacuum pump (10) in accordance with claim 1 or claim 2,
   characterized in that
   the rotor sections (16) are each formed by a rotor disk manufactured separately from the rotor shaft (14) and fastened to the rotor shaft (14).
4. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   the pure rotor region (28) is arranged directly in front of or behind a lateral tap (26) or near a lateral tap (26) in the axial direction.
5. A vacuum pump (10), in particular a turbomolecular pump, comprising

   at least one rotor (12) which has a rotor shaft (14) and at least one rotor section (16) which is arranged at the rotor shaft (14) and which comprises a plurality of rotor blades (18) arranged distributed in the peripheral direction; and

   at least one stator which is associated with the rotor (12) and which has at least one stator section (22) which follows a rotor section (16) in the axial direction and which comprises a plurality of stator blades (24) arranged distributed in the peripheral direction,

   wherein at least one pure stator region (29), in which at least two stator sections (22) follow one another without a rotor section (16) disposed therebetween, is provided in an axial region of the rotor (12) into which no lateral tap (26) opens,
   characterized in that
   an axial spacing is provided between the two stator sections (22) of the pure stator region (29).
6. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   a lateral tap (26) is provided in at least one region of the rotor.
7. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   a lateral tap (26) is arranged between an inlet (30) and an outlet (32) of the vacuum pump (10).
8. A vacuum pump (10) in accordance with at least one of the claims 1 to 5,
   characterized in that
   the vacuum pump (10) does not have a lateral tap.
9. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   a stator section (22) is arranged in the axial direction between the rotor section (16) which is the first rotor section in the pump direction (P) and the rotor section (16) which is the second rotor section in the pump direction (P).

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