WO2012110378A1

WO2012110378A1 - Stator element and high-vacuum pump

Info

Publication number: WO2012110378A1
Application number: PCT/EP2012/052122
Authority: WO
Inventors: Heinrich Engländer; Michael Richter
Original assignee: Oerlikon Leybold Vacuum Gmbh
Priority date: 2011-02-17
Filing date: 2012-02-08
Publication date: 2012-08-23
Also published as: EP2676034A1; CN103380301B; CN103380301A; JP2014505833A; DE202011002809U1

Abstract

A stator element for a high-vacuum pump is arranged downstream of the last rotor element in the pumping direction (26). The stator element has a housing element (28), which is connected to a housing (12) of the high-vacuum pump. A plurality of stator webs (32), which are distributed regularly in the circumferential direction, are arranged on an inner surface (30) of the housing element (28).

Description

Stator element and high vacuum pump

The invention relates to a stator for a high vacuum pump and a high vacuum pump.

Many high-vacuum pumps today are constructed in two stages, wherein the first stage is formed by a Turbomoieku! Arpumpe, which is followed in the conveying direction by a molecular or gas friction pump. A turbomolecular pump has a plurality of rotor elements arranged in a housing, wherein each rotor element has a plurality of rotor blades. Between the individual rotor elements fixedly connected to the stator stator elements are arranged, which have a plurality of stator vanes. By way of example, a Holweck stage is provided as the molecular or gas friction pump adjoining the turbomolecular pump. The Holweck stage has, for example, a cylinder connected to the last rotor element in the direction of flow. The cylinder is surrounded by one or more threads. The delivery cross sections of a molecular or gas friction pump are in this case smaller than the mean free path of the gases to be delivered, this has the consequence that the Gasteiichen essentially but against the walls do not meet against each other. Such a Holweck stage is described for example in DE 19 632 375, wherein this Holweck stage has a plurality of concentric with each other fixedly connected to the last rotor element cylindrical elements. Between these non-rotating elements are arranged with threads, so that by rotation of the cylindrical elements, a gas transport takes place in the threads. The introduction of the pumped gas in the Holweck stage takes place here through openings in the last rotor element or a perforated disc which is connected to the rotor and carries the cylindrical elements of the Holweck stage. Since the gas thus passes through the holes in the disk tn the Holweck stage, flow losses occur, which entail a reduction in throughput.

The object of the invention is to provide a stator for a high vacuum pump and a high vacuum pump, with which a flow rate improvement can be achieved.

The object is achieved according to the invention by a stator element according to claim 1 or by a high vacuum pump according to claim 11.

The stator element according to the invention is arranged immediately downstream in the axial conveying direction of the last rotor element of a high-vacuum pump, in particular a turbomolecular pump. In this case, a molecular or gas friction pump can in turn be arranged downstream of the stator element according to the invention in the conveying direction. The stator element according to the invention has a housing element which is connected to the housing of the high-vacuum pump, in particular the turbomolecular pump. Instead of a housing element itself, it can also be a carrier element connected to the housing or surrounded by a further housing. Stator bars are arranged on the inside of this housing or carrier element. In this case, the stator webs preferably extend only over the stator vanes of the individual stator elements arranged between the rotor elements total effective width of the rotor elements, and project from the inside of the housing element inwardly to a particular cylindrical rotor extension. Preferably, in contrast to conventional stator vanes arranged between rotor elements, the stator webs are open inwards. Furthermore, the stator webs are preferably arranged obliquely or teii-spirally corresponding to a web of a thread. As a result, an active pumping action of the stator webs can be realized, which counteracts a backflow, as occurs in conventional stator blades, and also supports the conveying effect.

Already by such an arrangement and configuration of Statorfiügel a throughput improvement can be achieved. In this case, it is particularly preferred that, when the stator element is mounted, the stator web surround a cylindrical rotor extension, wherein the cylindrical rotor attachment is preferably connected to the last rotor element and thus likewise rotates.

In a preferred embodiment, an essential aspect of the invention is that the configuration of the Statorfiügel is selected such that the interaction at Holweck stages between the opposite threaded walls and the cylindrical member is reduced, or even avoided. According to the invention, a large delivery cross-section is preferably provided in the thread, which supports the pumping action, in particular in the region close to the inner rotor attachment.

Preferably, the stator webs extend in the circumferential direction along the inside of the housing element. In this case, each individual stator web is preferably a partial thread, which, however, only extends around part of the circumference. In the circumferential direction, the stator webs preferably have a length of at least one sixth, in particular at least one fifth and more preferably at least a quarter of the entire circumference. However, the stator webs always have a length which is less than half, in particular smaller than one third of the total volume. The stator webs in this case have an inclination to the longitudinal or conveying direction of the pump.

Preferably, the stator webs have a radial depth that is greater than the mean free path of the Gasteiichen to be funded, in particular, the radial depth is at least 1.2 times, preferably 1.5 times and in particular at least 2.5 Fache the average free Wegiänge of Gasteiichen to be promoted. As a result, the throughput can be further improved. In a preferred embodiment, the radial depth of the stator webs is thus at least 10 mm, in particular at least 15 mm and particularly preferably at least 20 mm. The maximum radial depth is in this case a maximum of 40 mm, in particular a maximum of 30 mm and particularly preferably a maximum of 20 mm.

For further increase in throughput, the passage height or the distance between two adjacent stator webs is selected to be large and is preferably 30 to 60%, in particular 45 to 55% of the chord depth.

Furthermore, it is preferred that adjacent stator webs overlap in the circumferential direction by at least 10 to 70%, preferably 20 to 70% and particularly preferably 30 to 60%.

Furthermore, it is preferred that the stator element is designed such that all, provided between two adjacent stator webs inlet openings lie in the same entrance level. The gas particles emerging from the last stator element of the turbomolecule pump therefore enter directly into one of the inlet openings of the stator webs. The preferably located in an entrance level inlet openings in the circumferential direction preferably have an opening width of at least 10 to 15% of the circumference. In the circumferential direction, preferably at least four, in particular six and particularly preferably eight stator bars are provided. Furthermore, it is preferred that the stator webs extend radially inwardly have decreasing depth. In the conveying direction, the depth in the stator webs thus preferably decreases. In this case, the stator webs preferably have the same inner diameter, so that a constant small distance from the cylindrical rotor extension is realized.

All of the above-described preferred embodiments of the stator element bring about an improvement in the throughput, in particular in the case of different combinations of these features.

Furthermore, the invention relates to a high vacuum pump, which in particular has a turbomolecular pump, wherein the last rotor element in the conveying direction, a stator with stator bars, as described above, is arranged downstream. It is particularly preferred in this case that the stator directly adjoins the last rotor element, wherein in particular between the last rotor element and the stator according to the invention no conventional stator of a turbomolecular pump is provided. Furthermore, it is preferred that a cylindrical rotor extension is connected to the last rotor element, which is surrounded by the stator element or the individual stator webs of the stator element. This co-rotating cylindrical rotor lug serves to seal the insides of the individual stator webs in order to minimize the amount of backflowing gas and to support the conveying mechanism in the region close to the cylinder.

The invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying drawings.

Show it :

Fig. 1: A schematic sectional view of an inventive

High vacuum pump. 2 shows a schematic perspective sectional view of a preferred embodiment of the stator element according to the invention.

In the illustrated embodiment, the high vacuum pump has a turbomolecular pump 10. This has in a housing 12 on a bearing 14 arranged on a rotor 16. The rotor 16 has a plurality of rotor elements 18, each having a plurality Rotorflugi. Between the rotor elements 18, stator elements 20 are arranged which are fixed in the housing 12 via stator rings 22. With the aid of the turbomolecular pump 10, the gas is conveyed through a pump inlet 24 in the conveying direction 26.

With the housing 12 of the turbomolecular pump 10, a housing member 28 is connected. The housing element 28 has on its inner side 30 stator webs 32. The stator webs 32 are arranged directly adjacent to the last rotor element in the conveying direction 26, so that no further intermediate element, in particular no stator element, is provided between the last rotor element 18 and the stator webs 32.

With the last rotor element 18, a cylindrically shaped rotor lug 38 is firmly connected, so that the rotor lug 38 rotates together with the rotor 16. The stator webs 32 surround the rotor extension 38.

In the illustrated embodiment, the housing member 28 has a flange 34, via which the housing member 28 is connected by means of screws 36 with the housing 12 of the turbomolecular pump.

In the illustrated Ausführungsbeispie! On the inside 30 of the housing element 28, six stator bars (FIG. 2) are distributed regularly. The stator webs 32, which are inclined in accordance with a partial thread, each extend over approximately one quarter to one third of the total Perimeter, with adjacent Statorstege 32 each overlap by about 55%.

The stator webs 32 have a radial depth t (FIG. 1) which is greater than the mean free path length of the gas paths to be conveyed. In the illustrated Ausführungsbetspiel the depth t is 10 to 20 mm. In the illustrated preferred embodiment, the depth t decreases in the conveying direction. Thus, the depth ti of the region of the stator webs 32 immediately adjacent to the set rotor element is deeper than the depth t ₂ in a region farther away therefrom. The inclination or orientation of the individual stator webs 32 relative to one another is selected such that a passage height h (FIG. 2) of two adjacent startor wings 32 amounts to at least 30 to 60% of the blade depth t.

Between two adjacent stator webs in each case an inlet opening 40 is formed. Preferably, all inlet openings 40 are located in a common entry plane which adjoins directly the lower wing plane of the last rotor element 18 in the conveying direction 26. In the circumferential direction, the inlet openings 40 have an opening width of 10 to 15% of the entire circumference.

Claims

claims

1. Statorelement for a high vacuum pump, which is arranged downstream of the in the conveying direction (26) last rotor element (18) with a housing (12) of the high vacuum pump (10) connectable housing element (28) and on an inner side (30) of the housing element ( 28) arranged Statorstegen (32).

2. Stator element according to claim 1, characterized in that the stator webs (32) extend in the circumferential direction along the inner side (30) and preferably a length of at least one sixth, in particular at least one fifth and more preferably at least a quarter but preferably less than half , in particular less than one third of the entire circumference.

3. Stator element according to claim 1 or 2, characterized in that the stator webs (32) have a radial depth (t) which is greater than the mean free path of the gas particles to be conveyed, wherein the radial depth (t) in particular by at least the 1.2 times, preferably 1.5 times and more preferably 2.5 times greater than the mean free path of the gases to be delivered is.

4. Statorelement according to one of claims 1 to 3, characterized in that the Statorstege (32) have a radial depth (t) of at least 10 mm, preferably at least 15 mm and more preferably at least 20 mm, wherein the maximum radial depth (t ) is less than 40 mm, preferably less than 30 mm, and more preferably less than 20 mm.

5. Statoreiement according to one of claims 1 to 4, characterized in that a passage height (h) between two adjacent stator webs (32) 30 to 60%, preferably 45 to 55% of the chord (t) is.

6. stator element according to one of claims 1 to 5, characterized in that adjacent stator webs (32) in the circumferential direction by 10 to 70%, preferably 20 to 70% and more preferably overlap 30 to 60%.

7. stator element according to one of claims 1 to 6, characterized in that all between adjacent stator webs (32) provided inlet openings (40) lie in the same entrance level.

8. stator element according to one of claims 1 to 7, characterized in that in the circumferential direction at least four, preferably at least six and more preferably at least eight stator webs (32) are provided.

9. stator element according to one of claims 1 to 8, characterized in that between the Statorstegen (32) provided inlet openings (40) in the circumferential direction have an opening width of at least 10 to 15% of the entire circumference.

10. stator element according to one of claims 1 to 9, characterized in that the radial depth (t) of the stator webs (32) reduces radially in the conveying direction.

11. High vacuum pump, in particular turbomolecular pump, with a rotor elements (16) having a plurality of rotor elements (18) and a stator element downstream of the last rotor element (18) in the conveying direction (26) according to one of claims 1 to 10,

12. High vacuum pump according to claim 11, characterized in that the stator element, in particular the stator webs (32) directly adjacent to the last rotor element (18).

13. High vacuum pump according to claim 11 or 12, characterized in that in the conveying direction (26) last Rotoreiement (18) with a cylindrical rotor extension (38) is connected, which is surrounded by the stator in particular the Statorstegen (32).