US20140356146A1

US20140356146A1 - Vacuum pump

Info

Publication number: US20140356146A1
Application number: US14/288,534
Authority: US
Inventors: Mirko Mekota; Peter Vorwerk; Bernd Hofmann; Johannes Schnarr
Original assignee: Pfeiffer Vacuum GmbH
Current assignee: Pfeiffer Vacuum GmbH
Priority date: 2013-05-29
Filing date: 2014-05-28
Publication date: 2014-12-04
Also published as: CN104214112B; JP2014231835A; DE102013210109A1; EP2808549A1; JP6162644B2; EP2808549B1; CN104214112A

Abstract

A vacuum pump includes a rotor and a rotary bearing, which is to be supplied with an operating medium, for the rotatable support of the rotor, wherein the rotor has a conveying section, in particular a conical conveying section, for supplying the operating medium to the rotary agent. A conveying pump is provided for conveying the operating medium and/or an operating medium store is provided having an absorbent storage means for the operating medium. Further, at least one wick is provided which is in contact with the conveying section to transfer the operating medium provided from the conveying pump and/or from the absorbent storage means to the conveying section in a desired quantity.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a vacuum pump, in particular to a turbomolecular pump, having a rotor and having a rotary bearing for the rotatable support of the rotor.
2. Description of the Prior Art
Such vacuum pumps typically comprise an apparatus for supplying the rotary bearing with an operating medium, said apparatus comprising a conical section of the rotor to which the operating medium is transferred. The operating medium is conveyed by the centrifugal and capillary forces acting in the operation of the vacuum pump to the rotary bearing via the conical section.
Vacuum pumps are known which comprise an operating medium store for the operating medium having an absorbent storage means which is saturated with the operating medium and which has one or more wipers which are in contact with the conveying section and via which the operating medium is transferred to the conveying section. Vacuum pumps are furthermore known in which an operating medium provided in a storage tank is transferred to the conveying section via a wick. In addition, vacuum pumps are known which comprise a conveying pump for the operating medium, wherein the operating medium provided by the conveying pump is trickled onto the conveying section.
No continuous supply of the rotary bearing with a precisely defined quantity of the operating medium can be achieved using the described apparatus. The apparatus having an operating medium store and the apparatus having a wick fed from a storage tank each in particular result in too small a quantity of conveyed operating medium, whereas the embodiment with an oil pump provides too high an operating medium quantity.
It is therefore an object of the invention to provide a vacuum pump which ensures a continuous supply of a rotary bearing of the vacuum pump with a desired quantity of an operating medium.

SUMMARY OF THE INVENTION

The object of the invention is achieved by a vacuum pump, in particular a turbomolecular pump, that comprises a rotor and a rotary bearing, which is to be supplied with an operating medium, for the rotatable support of the rotor, wherein the rotor has a conveying section, in particular a conical conveying section, for supplying the operating medium to the rotary agent. A conveying pump is furthermore provided for conveying the operating medium and/or an operating medium store is provided having an absorbent storage means for the operating medium. In addition, at least one wick is provided which is in contact with the conveying section to transfer the operating medium provided from the conveying pump and/or from the absorbent storage means to the conveying section.
It was recognized within the framework of the invention that a continuous supply of the rotary bearing with an exactly predefinable quantity of an operating medium provided from a conveying pump or from an operating medium store is achieved by the use of a wick for transferring the operating medium to the conveying section of the rotor. The wick effects a regulation of the operating medium quantity which is transferred to the conveying section and consequently reaches the rotary bearing.
Advantageous embodiments of the invention are described in the dependent claims, in the description and in the Figures.
In accordance with an advantageous embodiment, an outlet for the operating medium is provided and can be supplied with the operating medium from the conveying pump, wherein the wick is arranged such that the wick closes the outlet. It is thereby ensured that the operating medium provided at the outlet is substantially only conveyed onward via the wick so that an effective regulation of the transferred quantity of operating medium is achieved and the transfer of too great a quantity of operating medium is reliably avoided substantially independently of the quantity of operating medium conveyed by the conveying pump.
A further embodiment provides that an outlet for the operating medium is provided which can be supplied with the operating medium from the conveying pump, with the wick extending lengthways through the outlet. A good transfer of the operating medium provided at the outlet to the wick can thereby be achieved. The wick can close the outlet such that substantially the total quantity of operating medium exiting via the outlet is conveyed through the wick and consequently a particularly effective regulation of the conveyed quantity of operating medium takes place. The wick can be clamped in the outlet and can thereby be fixed in its position, in particular such that it is kept in contact with the conveying section.
The outlet is preferably formed by an open end of a conveying passage for the operating medium. The wick can extend through the outlet into the passage so that the wick is arranged over part of its length in the passage.
The wick can substantially fill the complete passage cross-section at least over a part of its length arranged in the passage. A particularly effective transfer of the provided operating medium to the wick is thereby achieved, with it being reliably ensured that the operating medium is only conveyed through the outlet via the wick. At the same time, an effective fixing of the wick in the passage is achieved.
In accordance with an advantageous embodiment, the conveying pump has means for setting the conveying performance of the conveying pump. The value of the quantity of operating medium continuously supplied to the rotary bearing can consequently be set flexibly. The means for setting the conveying performance can comprise a means for inputting a desired value for the conveying performance by a user. The means for setting the conveying performance can comprise electronic means to detect a desired value, in particular a desired value set by a user, for the conveying performance.
A preferred further development provides that the wick is at least regionally in contact with the storage means of the operating medium store. A direct transfer of the operating medium provided in the operating medium store to the wick is thereby achieved. The wick improves the transfer of the operating medium from the operating medium store to the conveying section in comparison with a direct contacting of the conveying section by the operating medium store and ensures a continuous transfer of the desired operating medium quantity to the conveying section.
An advantageous embodiment provides that the wick is wound around the operating medium store. The wick can be wound around the operating medium store at least once or a multiple of times. In this respect, at least a part of the section of the wick wound around the operating medium store can be in direct contact with the storage means. A close contact of the wick with the storage means over a wide area is thereby achieved with a simultaneously simple manufacturing capability of the arrangement.
In accordance with a further advantageous embodiment, the wick is fastened to the operating store, preferably by a fastening means extending at least partly through the wick and the storage means. The wick can thereby be fixed such that it is held in contact with the conveying section of the rotor. The fastening means can e.g. be configured in needle form and can be pushed into the wick and the storage means.
The operating medium store can have an opening into which the conveying section of the rotor shaft can project. A section of the wick can pass across the opening at least partly and in particular completely and can in so doing preferably be in contact with the conveying section. When the wick is fastened to the operating medium store at both sides of the opening, the wick is reliably held in its position contacting the conveying section. The operating medium store can, for example, extend in ring form around the conveying section and can have an at least approximately annular base shape.
The wick can extend at least once and preferably a multiple of times completely across the opening. For example, the wick can extend completely across the opening at least twice, with the conveying section being arranged between the two sections of the wick extending across the opening.
The storage means is preferably formed at least regionally by a material absorbent for the operating medium, e.g. by a felt or by a comparable absorbent material, in particular a textile and/or porous absorbent material.
The storage means can comprise a plurality of disks which are preferably stacked on one another. For example, the disks can each have an annular base shape and can be stacked on one another such that their base surfaces substantially overlap. Such an operating medium store can be manufactured simply, with a desired storage capacity and a desired shape of the operating medium store, for example a substantially annular base shape, being able to be achieved with a small effort.
The wick can be in contact with the conveying section over its longitudinal side. Alternatively or additionally, the wick can have an open end and can be in contact with the conveying section via the open end. In both cases, a metered transfer of the operating medium to the conveying section is ensured.
The conveying section preferably has an external diameter which becomes larger toward the rotary bearing. The operating medium transferred to the conveying section can be conveyed to the rotary bearing in this embodiment without any additional effort by the centrifugal force and the capillary action acting in the operation of the vacuum pump.
The vacuum pump is preferably configured such that the operating medium can be conveyed in a circuit during the operation of the vacuum pump. The operating medium is in this respect transferred, for example, from the conveying pump and/or from the operating medium store to the wick, is transferred from the wick to the conveying section, is conveyed via the conveying section to the rotary bearing, where it satisfies its function required for the operation of the rotary bearing, and is finally conveyed from the rotary bearing via the circuit back to the conveying pump and/or to the operating medium store. A conveying means arranged between the rotary bearing and the conveying pump or a conveying means arranged between the rotary bearing and the operating medium store can be provided for the return of the operating medium from the rotary bearing to the conveying pump and/or to the operating medium store. The conveying means can be a capillary conveying means such as a wick or a section of a wick.
The conveyed quantity of operating medium can be set to a desired value by a corresponding selection of the material of the wick and/or of the cross-section of the wick. To be able to withstand the thermal conditions prevailing in the operation of the vacuum pump, the wick is preferably formed from a temperature-resistant material.
The rotary bearing is preferably formed as a roller element bearing, in particular as a ball bearing. The operating medium can be a lubricant for the rotary bearing or for the roller element bearing which lubricant can in particular comprise an oil.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in the following by way of example with reference to advantageous embodiments and to the enclosed drawings. The drawings show:

FIG. 1 a schematic view of a vacuum pump in accordance with an embodiment of the invention; and

FIGS. 2 to 5 respectively, a plan view of an operating medium store having a wick for a vacuum pump in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The vacuum pump shown schematically in FIG. 1 comprises a rotor 10 which is rotatably supported about an axis of rotation 32 by a roller element bearing 12. The rotor 10 comprises a rotor shaft shown only schematically in FIG. 1 and a plurality of turbomolecular rotor disks 30 arranged at the rotor shaft and likewise only shown schematically in FIG. 1. The rotor disks 30 extending radially to the rotor shaft are each disposed opposite one of a plurality of stator disks which are not shown in FIG. 1 and which are arranged between the rotor disks 30, the rotor disks forming a turbomolecular pump stage of the turbomolecular pump with the stator disks.
At the end of the rotor shaft remote from the rotor disks 30, a conical conveying section 14 is provided which is rotationally fixedly connected to the rotor shaft, which is coaxial to the axis of rotation 32 and which has an external diameter increasing in size toward the rotary bearing 12.
A conveying pump 16 is provided for supplying the rotary bearing 12 with an operating medium and conveys the operating medium provided at its inlet into a conveying passage 24 which extends in the direction of the conveying section 14. The end of the passage 24 facing the conveying section 14 forms an outlet 22 for the operating medium. This outlet 22 is closed by a wick 20 which extends through the outlet 22 into the conveying passage 24 and is arranged over a substantial part of its length within the conveying passage 24.
A section of the wick 20 arranged outside the conveying passage 24 extends from the outlet 22 to the conveying section 14 and contacts the conveying section 14 such that the operating medium conveyed in the wick 20 is transferred to the conveying section 14 by capillary action.
In the operation of the vacuum pump, an operating medium is introduced into the conveying passage 24 by the conveying pump 16 and is conveyed in the direction of the outlet 22 where it is transferred to the wick 20. The operating medium is transferred from there to the conveying section 14 as a result of the sliding contact between the wick 20 and the conveying section 14.
The operating medium is conveyed by the centrifugal force and by the capillary action acting on the rotation of the conveying section 14 in the direction of the external diameter of the conveying section 14 increasing in size and consequently toward the rotary bearing 12 in which it satisfies its function, in particular its lubricating function, required for the operation of the rotary bearing 12. As shown by arrows in FIG. 1, the vacuum pump comprises a device for conveying the operating medium from the rotary bearing 12 back to the conveying pump 16 so that the operating medium is conveyed in a closed circuit 28.
FIG. 2 shows an operating medium store 18 and a wick 20 for a vacuum pump in a plan view, i.e. in the direction of the axis of rotation of the vacuum pump.
The operating medium store 18 has an annular base shape and is formed by a plurality of disks which are stacked on one another in the direction of view, which are saturated with an operating medium and which are composed of an absorbent material such as felt. The interior of the annular disks forms an opening of the operating medium store 18 into which the conveying section 14 of the vacuum pump indicated by dashed lines in FIG. 2 extends.
The operating medium store 18 is wound around by the wick 20 several times along its outer periphery, with the outer periphery of the operating medium store 18 and the wick 20 contacting one another directly so that the operating medium provided in the operating medium store 18 is transferred to the wick 20.
The wick 20 comprises a section extending across the opening of the operating medium store 18. The wick 20 is fixed to the operating medium store 18 at both sides of this section in each case via a needle-like fastening means 26. In the state installed in the vacuum pump, the longitudinal side of the wick 20 tangentially contacts the conveying section 14 so that the operating medium conveyed in the wick 20 is transferred to the conveying section 14 by capillary action.
The arrangement shown in FIG. 3 substantially corresponds to the arrangement shown in FIG. 2. In the arrangement shown in FIG. 3, the wick 20 extends twice across the opening of the operating medium store 18. In the state installed in the vacuum pump, the conveying section 14 is arranged between the two sections of the wick 20 extending across the opening of the operating medium store 18 so that the conveying section 14 is contacted by the wick 20 at both sides, whereby the quantity of operating medium transferred to the conveying section 14 is increased.
The arrangement shown in FIG. 4 substantially corresponds to the arrangements shown in FIGS. 2 and 3, with the wick 20 shown in FIG. 4 having an open end and being in contact with the conveying section 14 via the open end. A region of the wick 20 adjacent to the open end is led through a cuff 34 which is fastened to the operating medium store 18 together with the wick 20, whereby the wick 20 is held in its position contacting the conveying section 14.
The arrangement shown in FIG. 5 substantially corresponds to the arrangement shown in FIG. 4, with the wick 20 shown in FIG. 5 having two open ends via which the wick 20 is respectively in contact with the conveying section 14 so that the quantity of operating medium transferred to the conveying section 14 is increased with respect to the arrangement shown in FIG. 4.

Claims

What is claimed is:

1. A vacuum pump having a rotor (10) and having a rotary bearing (12), which is to be supplied with an operating medium, for the rotatable support of the rotor (10), wherein the rotor (10) has a conveying section (14) for conveying the operating medium to the rotary bearing (12);

further having at least one of a conveying pump (16) for conveying the operating medium and an operating medium store (18) with an absorbent storage means for the operating medium;

and further comprising at least one wick (20), the wick being in contact with the conveying section (14) to transfer the operating medium provided from the at least one of the conveying pump (16) and the absorbent storage means to the conveying section (14).

2. The vacuum pump in accordance with claim 1, wherein the vacuum pump is a turbomolecular pump.

3. The vacuum pump in accordance with claim 1, wherein the conveying section is a conical conveying section.

4. The vacuum pump in accordance with claim 1, further comprising an outlet (22) for the operating medium, wherein the outlet can be supplied with the operating medium from the conveying pump (16), with the wick (20) being arranged such that the wick (20) closes the outlet (22).

5. The vacuum pump in accordance with claim 1, further comprising an outlet (22) for the operating medium, wherein the outlet can be supplied with the operating medium from the conveying pump (20), with the wick (20) extending lengthways through the outlet (22).

6. The vacuum pump in accordance with claim 4, wherein the outlet (22) is formed by an open end of a conveying passage (24) for the operating medium.

7. The vacuum pump in accordance with claim 5, wherein the outlet (22) is formed by an open end of a conveying passage (24) for the operating medium.

8. The vacuum pump in accordance with claim 1, wherein the conveying pump (16) has means for setting the conveying performance of the conveying pump (16).

9. The vacuum pump in accordance with claim 1, wherein the wick (20) is at least regionally in contact with the storage means of the operating medium store (18).

10. The vacuum pump in accordance with claim 1, wherein the wick (20) is wound around the operating medium store (18).

11. The vacuum pump in accordance with claim 1, wherein the wick (20) is fastened to the operating medium store (18).

12. The vacuum pump in accordance with claim 10, wherein the wick (20) is fastened to the operating medium store (18) by a fastening means (26) extending at least partly through the wick (20) and the storage means.

13. The vacuum pump in accordance with claim 1, wherein the storage means is at least regionally formed by a felt.

14. The vacuum pump in accordance with claim 1, wherein the storage means comprises a plurality of disks which are preferably stacked on one another.

15. The vacuum pump in accordance with claim 1, wherein the wick (20) is in contact with the conveying section (14) over its longitudinal side.

16. The vacuum pump in accordance with claim 1, wherein the wick (20) has an open end and is in contact with the conveying section (14) via the open end.

17. The vacuum pump in accordance with claim 1, wherein the conveying section (14) has an external diameter becoming larger toward the rotary bearing (12).

18. The vacuum pump in accordance with claim 1, wherein the vacuum pump is configured such that the operating medium can be conveyed in a circuit during the operation of the vacuum pump.