EP3051145B1 - Vacuum pump - Google Patents

Description

The present invention relates to a vacuum pump, in particular a turbomolecular pump, with a housing, a rotatably mounted shaft for at least one pump stage and a holder for a bearing for supporting the shaft, which is located in a suction area of the vacuum pump.

Vacuum pumps are used in various technical fields, for example in semiconductor production, in order to create a vacuum required for a particular process.

Basically, there is the problem that particles - for example small chips or chips - are sucked out of the space to be evacuated and get into the vacuum pump. There you may cause considerable damage. The penetration of particles is particularly problematic in the case of turbomolecular pumps, which as a rule have at least one pump stage with very rapidly rotating components. If an aspirated particle hits one of these components, it can cause serious damage to the pump or even destroy it.

It is known to provide a protective grille in an area upstream of an inlet flange of the vacuum pump, which grille catches potentially dangerous particles before they enter the pump. Such a protective grid is conventionally integrated in a centering ring, which is used when the pump is connected to the device to be evacuated (cf. EP 1 669 608 A2 ). Often, however, are on the devices Flange types are provided for connecting the pump to which no centering ring can be attached. This means that no protective grille can be installed to protect the vacuum pump.

It is therefore an object of the present invention to provide a vacuum pump which is protected in a simple and efficient manner against damage caused by particles sucked in.

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

It is provided according to the invention to provide a protective device which prevents the penetration of objects or particles into the suction area of the vacuum pump and which is attached to the holder for the bearing of the shaft. In other words, the already existing holder is used to reliably fix a protective grille protecting the pump in the suction area of the vacuum pump. The integration of the protective grille into the pump eliminates the need to maintain and install a separate protective grille component. Furthermore, the problem described at the beginning that conventional protective grilles which are integrated in a centering grille cannot be used with many flange types is eliminated.

Further embodiments of the invention are specified in the description, the claims and the accompanying drawings.

According to one embodiment, the holder comprises a central section receiving the bearing and a plurality of struts which extend at least substantially in the radial direction. The struts connect the central section with a housing ring connected to the housing. The In this embodiment, the protective device is attached to at least one of the struts, the central section and / or the housing ring.

If the protective device is arranged on the side of the holder assigned to the suction side of the vacuum pump, it simultaneously protects the holder.

The protective device preferably comprises a grid. The structure of the grid can in principle be constructed in any way. For example, the grid has a honeycomb structure. The structure can also be constructed from square and / or round elements / cells.

The protective device can have at least one reinforced area which is more stable than other areas of the protective device. For example, the reinforced area is opaque. It can be generated, for example, by applying additional material to the grid. However, it is also possible to form the reinforced area in one piece with the grid.

The reinforced region can comprise at least one reinforcement segment which is arranged in the region of the housing ring. In particular, the reinforcement segment surrounds the protective device in the circumferential direction. In other words, the reinforcement segment is arranged in a radial outer edge region of the protective device. It can limit this at least in sections or even completely surround it in a radial direction towards the outside.

Additionally or alternatively, the reinforced area can comprise a reinforcing element that extends at least in sections in the radial direction. In particular, the reinforcing element is arranged in the region of at least one of the struts, in particular wherein the reinforcing element at least partially, preferably completely, covers the struts in the axial direction of view. For example the geometry of the reinforcing element essentially corresponds to an axial projection of the at least one strut. By adapting the geometry of the reinforcement element to that of the strut, it is ensured that the protective device receives the greatest possible stability without creating additional flow resistance in the suction area of the vacuum pump, which would reduce its efficiency.

The same applies to a reinforcement section, which can optionally be additionally or alternatively provided. This can be arranged in the area of the central section. In particular, the reinforcement section at least partially, preferably completely, covers the central section in the axial viewing direction.

As already mentioned, it is possible to form the reinforced area in one piece. The grid can be connected in one piece, in particular continuously, to at least part of the reinforced area of the protective device. The reinforced area - or at least parts thereof - can also initially be manufactured as separate components and then connected to the grid.

According to one embodiment, the reinforced area of the protective device, the at least one strut, the housing ring and / or the central section have at least one fastening section for fastening the protective device to the holder. For example, the fastening section comprises a bore. For example, a through opening can be provided in the reinforced area, which is at least partially surrounded by the reinforcement. A corresponding bore can be provided in the strut, the housing ring and / or the central section, which is provided, for example, with an internal thread. As a result, the protective device can be attached to the holder in a simple manner by means of screws. However, it is also conceivable to provide clamping elements with which the protective device is clamped on the holder. The Clamping elements can be separate components or can be provided on the protective device and / or the holder.

In principle, every type of fastening is conceivable. In addition to a non-positive connection, for example by means of suitable clamping elements, or a positive connection, for example by screwing, a material connection can also be provided, for example by welding, soldering and / or gluing. The types of fastening can also be combined.

The protective device can be designed such that it interacts with the geometry of the holder in order to enable the protective device to be positioned as simply and reliably as possible. For example, the housing ring and / or the central section have a recess for receiving at least a section of the protective device. The recess can be a ring step, for example.

The protective device is preferably designed such that it conforms to the geometry of the holder. With a corresponding design of the holder, the protective device can therefore span a three-dimensional surface which essentially corresponds to a geometry of the surface of the holder facing the protective device. In particular, the protective device forms a truncated cone in sections. In other words, the protective device does not necessarily have to be an essentially flat element which is placed on the holder. In the case of a more complex geometry of the holder, it is advisable to adapt the geometry of the protective device accordingly in order to be able to reliably fix it to the holder.

Fig. 1

eine Vakuumpumpe in einem Querschnitt,

Fig. 2 bis 5

verschiedene Ausführungsformen einer Schutzeinrichtung einer erfindungsgemäßen Vakuumpumpe,

Fig. 6

eine weitere Ausführungsform der Schutzeinrichtung in einem Querschnitt und

Fig. 7 und 8

eine Ausführungsform einer Halterung der erfindungsgemäßen Vakuumpumpe in einer Draufsicht bzw. einer teilweisen Schnittansicht.

The present invention is explained below purely by way of example on the basis of advantageous embodiments and with reference to the accompanying drawings. Show it:

Fig. 1

a cross section of a vacuum pump,

2 to 5

different embodiments of a protective device of a vacuum pump according to the invention,

Fig. 6

a further embodiment of the protective device in a cross section and

7 and 8

an embodiment of a holder of the vacuum pump according to the invention in a plan view or a partial sectional view.

Fig. 1 shows a vacuum pump 10. It comprises a pump inlet 14 surrounded by an inlet flange 12 and a pump outlet 16, as well as several process gas pump stages for conveying the process gas present at the pump inlet 14 to the pump outlet 16. The vacuum pump 10 comprises a housing 18 and one arranged in the housing 18 Rotor 20 with a rotor shaft 24 rotatably mounted about an axis of rotation 22.

In the present exemplary embodiment, the pump 10 is designed as a turbomolecular pump and comprises a plurality of turbomolecular pump stages connected in series with one another with effective pumping, with a plurality of radial rotor disks 26 fastened to the rotor shaft 24 and stator disks 28 arranged between the rotor disks 26 and fixed in the housing 18, a rotor disk 26 and an adjacent stator disk 28 each form a turbomolecular pump stage. The stator disks 28 are held at a desired axial distance from one another by spacer rings 30.

The vacuum pump also comprises four Holweck pump stages, which are arranged one inside the other in the radial direction and have a pumping effect and are connected in series, but the construction of which will not be discussed in more detail below.

For the rotatable mounting of the rotor shaft 24, a roller bearing 32 in the area of the pump outlet 16 and a permanent magnet bearing 34 in the area of the pump inlet 14 are provided.

The permanent magnet bearing 34 is held by a holder 36 which comprises a central section 38 which is connected to a housing ring 42 via struts 40 (in FIG Fig. 1 only one strut 40 can be seen in a longitudinal section). The struts 40 are formed in one piece with the housing ring 42. The housing ring 42 is in turn an integral part of the housing 18 and also forms the inlet flange 12. In contrast to the embodiment shown, the housing ring 42 can also be detachably connected to the housing 18. According to an embodiment not shown, the central section 38 is formed in one piece with the struts 40.

When the pump 10 is in operation, the rotor disks 26 rotate at a very high speed in order to achieve the desired pump output. A particle sucked into the pump inlet 14 would collide with the first rotor disk 26 and damage it. Due to their high rotational speed, comparatively minor damage to the disk 26 can result in considerable damage to other components of the pump 10.

Fig. 2 shows an embodiment of a protective grille 44 which is placed on the holder 36 from above and fixed thereon in order to prevent particles from entering the pump 10. The protective grille 44 is essentially planar and has a reinforcing ring 46 on its outside in order to increase the stability of the protective grille 44.

The protective grille 44 has holes 48 which are used to attach the protective grille 44 to the holder 36, e.g. serve on the housing ring 42 and / or the struts 40. Holes 48 are each surrounded by an annular reinforcement 50 to facilitate attachment, e.g. by means of screws.

Fig. 3 shows an embodiment 44a of the protective grille, which is also provided with a reinforcing ring 46. In contrast to the embodiment according to Fig. 2 the part of the grating 44a which retains the harmful particles does not have a square grating structure. This makes it clear that the lattice structure can be chosen arbitrarily with regard to the geometry of the individual meshes of the lattice and / or their size, in order to provide the protective effect suitable for the respective application.

In addition to the radially outer reinforcing ring 46, the protective grid 44a has a radially inner reinforcing ring 46 'which delimits a central free space 52. In the installed position, the free space 52 is covered by the central section 38 from below. Holes 48, which are surrounded by annular reinforcements 50, are also provided for fastening the protective grid 44a to the holder 36. Notwithstanding the in Fig. 2 In the embodiment shown, however, the holes 48 are arranged in a radially inner region in the vicinity of the reinforcement ring 46 '. The holes 48 enable the protective screen 44a to be fastened to the struts 40 and / or the central section 38. It goes without saying that, in addition or as an alternative, holes 48 can also be provided on the radially outer edge of the protective screen 44a, as is the case with the protective screen 44 in FIG Fig. 2 the case is.

Reinforcing webs 54, which extend in the radial direction from the holes 48 to the reinforcing ring 46, provide an additional reinforcement of the stability of the protective grid 44a. The reinforcing webs 54 preferably run in an angular position which the struts 40 also assume. That is to say, the webs 54 run essentially "on the struts 40, viewed in the axial direction of view, so that the webs 54 do not increase the flow resistance caused by the protective grid 44a. In other words, the webs 54 - provided they are not wider than the struts 40 - An increase in the stability of the protective grid 44a is achieved without adversely affecting the efficiency of the vacuum pump 10.

It is pointed out that the relative position of the holes 48 and the webs 54 can in principle be chosen freely. For example, it can be provided that the webs 54 each extend in an angular range between the holes 48 in the radial direction from the inside to the outside.

Fig. 4 shows a further embodiment 44b of the protective grille. The lattice structure of the protective lattice 44b differs from the respective lattice structure shown in FIGS Figures 2 and 3 shown protective grille 44, 44a. Although the protective grille 44b is provided with reinforcement rings 46, 46 ', similar to the grille 44a, the reinforcement webs 54 are designed to be significantly wider than in the case of the protective grille 44a, so that the fastening holes 48 can be made directly therein. There is therefore no need for any additional annular reinforcements 50, as are provided, for example, in the protective grids 44, 44a.

Fig. 5 shows a further embodiment 44c of the protective grille. It has no free space 52. The webs 54 converge in a central area of the protective grid 44c, but not necessarily in the middle. The webs 54 have holes 48, similar to the protective grid 44b. A hole 48 in the connection point of the three webs 54 enables the protective grid 44c to be fixed to the central section 38.

Fig. 6 clarifies that the protective grille does not necessarily have to have a planar shape. The embodiment 44d shown conforms to the geometry of the holder 36 facing the suction region of the pump 10. Since the central section 38 is set back in the axial direction relative to the inlet flange 12 and the side of the housing ring 42 facing the suction area, the surface of the struts 40 facing the suction side of the vacuum pump 10 runs obliquely to the axis of rotation 22. The geometry of the protective grid 44d is of this design Calculation, so that it has the geometry of a truncated cone in sections. In the central region, the protective grid 44d has holes 48 which are aligned with bores 56 in the central section 38, so that it can be fastened to the holder 36 by means of screws. Additional attachment points can be provided on the struts 40 and / or the housing ring 42 if necessary.

Fig. 7 shows a plan view of an embodiment of the holder 36, which is provided with a plurality of holes 56 in order to enable the fastening of a correspondingly designed protective grille. As in Fig. 8 can be seen, the housing ring 42 - in the present case, for example, a component separate from the housing 18 - has a ring step 58, so that the corresponding protective grille can be inserted in the holder 36 in the correct position. A ring step can also be provided in the area of the central section 38 in order to enable the coaxial positioning of the protective grille to be precise. Such a ring step on the central section 38 is formed, for example, by a flat cylindrical centering section 60 which is shown in FIG Fig. 7 is shown in dashed lines. It can extend into a free space of the protective grille, as it is, for example, based on the embodiments 44a, 44b (cf. free space 52 in FIG Fig. 3 or 4) was described. If the protective grille is to be attached to the holder 36 in a predefined angular position, it can be helpful to design the centering section 60 in cross-section not polygonally but possibly also asymmetrically.

In order to create a protective grille that is optimally suitable for the respective application, the position and the number of fastening holes 48 can be freely selected. The same applies to the design of the reinforcing components 46, 46 ', 50, 54. Instead of screw connections between the protective grille and the holder, alternative fastening concepts can also be used. For example, the protective grille and / or the holder can be provided with components that enable a clamp connection. Additionally or alternatively, a material connection - for example welded connection, soldered connection and / or adhesive connection - can also be provided.

LIST OF REFERENCE NUMBERS

10

vacuum pump

12

inlet flange

14

pump inlet

16

pump outlet

18

casing

20

rotor

22

axis of rotation

24

rotor shaft

26

rotor disc

28

stator

30

spacer ring

32

roller bearing

34

Permanent magnetic bearings

36

bracket

38

Central section

40

strut

42

housing ring

44, 44a, 44b, 44c, 44d, 44e

guard

46.46 '

reinforcement ring

48

hole

50

annular reinforcement

52

free space

54

strengthening web

56

drilling

58

annular step

60

centering

Claims (15)

1. A vacuum pump, in particular a turbomolecular pump, comprising
   a housing (18);
   a rotatably supported shaft (24) for at least one pump stage;
   a holder (36) for a bearing (34) for supporting the shaft (24), said holder (36) being disposed in a suction region (14) of the vacuum pump; and a protective device (44, 44a, 44b, 44c, 44d, 44e) preventing the penetration of objects into the suction region (14),
   characterized in that
   the protective device (44, 44a, 44b, 44c, 44d, 44e) is fastened to the holder (36).
2. A vacuum pump in accordance with claim 1,
   characterized in that
   the holder (36) comprises a central section (38) receiving the bearing (34); and a plurality of struts (40) which extend at least substantially in the radial direction and which connect the central section (38) to a housing ring (42) connected to the housing (18), with the protective device (44, 44a, 44b, 44c, 44d, 44e) being fastened to at least one of the struts (40), to the central section (38) and/or to the housing ring (42).
3. A vacuum pump in accordance with claim 1 or claim 2,
   characterized in that
   the protective device (44, 44a, 44b, 44c, 44d, 44e) is arranged at the side of the holder (36) facing the suction side of the vacuum pump.
4. A vacuum pump in accordance with at least one of the preceding claims,
   characterized in that
   the protective device (44, 44a, 44b, 44c, 44d, 44e) has a grid.
5. A vacuum pump in accordance with at least one of the preceding claims,
   characterized in that
   the protective device (44, 44a, 44b, 44c, 44d, 44e) has at least one reinforced region (46, 46', 50, 54) which has a higher stability in comparison with other regions of the protective device (44, 44a, 44b, 44c, 44d, 44e).
6. A vacuum pump in accordance with claim 5 together with claim 2,
   characterized in that
   the reinforced region comprises at least one reinforcement segment (46) which is arranged in the region of the housing ring (42).
7. A vacuum pump in accordance with claim 6,
   characterized in that
   the reinforcement segment (46) surrounds the protective device (44, 44a, 44b, 44c, 44d, 44e) at least sectionally, in particular completely, in the peripheral direction.
8. A vacuum pump in accordance with at least one of the claims 5 to 7,
   characterized in that
   the reinforced region comprises a reinforcement element (54) which extends at least sectionally in the radial direction.
9. A vacuum pump in accordance with claim 8,
   characterized in that
   the reinforcement element (54) is arranged in the region of at least one of the struts (40), in particular with the reinforcement element (54) at least partly, preferably completely, covering the strut (40) in the axial direction of view.
10. A vacuum pump in accordance with at least one of the claims 5 to 9,
    characterized in that
    the reinforced region comprises a reinforcement section (46') which is arranged in the region of the central section (38), in particular with the reinforcement section at least partly, preferably completely, covering the central section (38) in the axial direction of view.
11. A vacuum pump in accordance with at least one of the claims 5 to 10,
    characterized in that
    the reinforced region (46, 46', 50, 54) is formed in one piece.
12. A vacuum pump in accordance with at least one of the claims 5 to 11 together with claim 4,
    characterized in that
    the grid is integrally connected, in particular in a continuous structure, to at least one part of the reinforced region (46, 46', 50, 54) of the protective device (44, 44a, 44b, 44c, 44d, 44e).
13. A vacuum pump in accordance with at least one of the claims 5 to 12 together with claim 2,
    characterized in that
    the reinforced region (46, 46', 50, 54) of the protective device (44, 44a, 44b, 44c, 44d, 44e), the strut (40), the housing ring (42) and/or the central section (38) has/have at least one fastening section (48) for fastening the protective device (44, 44a, 44b, 44c, 44d, 44e) to the holder (36), in particular with the fastening section being designed as a bore (56).
14. A vacuum pump in accordance with any one of the claims 3 to 13 together with claim 2,
    characterized in that
    the housing ring (42) and/or the central section (38) has/have a recess for receiving at least one section of the protective device (44, 44a, 44b, 44c, 44d, 44e), in particular with the recess forming a ring stage (58).
15. A vacuum pump in accordance with at least one of the preceding claims,
    characterized in that
    the protective device (44e) spans a three-dimensional surface which in particular sectionally forms a truncated cone and which substantially corresponds to a geometry of the surface of the holder (36) facing the protective device (44e).

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