EP3034881A1 - Vacuum pump - Google Patents

Abstract

Vacuum pump (1) having a pump housing (2) which has a mounting flange (9) for connection to a recipient (21), in which a screen housing (3) is provided, which at least partially surrounds the pump housing (2) and the mounting flange (9 ) is formed almost completely or completely enclosing. Furthermore, the shield housing (3) comprises a mounting flange (8). The shield housing (3) essentially serves to shield the vacuum pump (1) and its components from strong external magnetic fields, e.g. in mass spectroscopy, which can generate a induced by eddy current effects braking torque on the rapidly rotating rotor, thus increasing the power consumption of the vacuum pump (1). The shield housing (3) is made of a magnetic field shielding material, preferably made of a ferromagnetic material.

Description

The invention relates to a vacuum pump with a pump housing.

Vacuum pumps are used in various technical processes, for example in semiconductor production, to remove a gas to be pumped, which is also referred to as pumping gas, from a volume to be evacuated and to generate a vacuum necessary for the respective technical process. Particular importance is given to turbomolecular pumps, which are operated at high speeds and are able to produce a vacuum with high purity.

For example, turbomolecular pumps in particular are used in high-resolution mass spectrometry. High-resolution mass spectrometry is widely used in the detection and identification of molecular structures and in the study of chemical and physical processes. A variety of different techniques for generating a mass spectrum using various collection and detection techniques are known. One such technique is, for example, a Fourier transform mass spectrometer.

The spectrometers generate very large magnetic fields with a magnetic flux density of, for example, 10 to 20 Tesla.

The vacuum pumps arranged in the vicinity of these mass spectrometers are likewise exposed to large magnetic fields. These magnetic fields can have a magnetic flux density of several hundred millitesla.

Due to the external magnetic field, a braking torque is generated in the vacuum pump with the rapidly rotating rotor due to eddy current effects, which results in an increase in power of the engine, since the engine is designed such that a predetermined speed is maintained. The power increase of the engine results in a heat increase in the vacuum pump. Due to the increase in heat, it is more difficult to generate low pressures, as the increase in heat causes increased molecular motion. In the worst case, malfunctions or even damage to the vacuum pump can occur as a result of rapid heating.

The technical problem underlying the invention is to provide a vacuum pump that can work even in applications with high magnetic field strengths without the described eddy current effects.

This technical problem is solved by a vacuum pump having the features according to claim 1.

The vacuum pump according to the invention with a pump housing, which has a connection flange for connection to a recipient, is characterized in that a screen housing is provided which at least partially and the connecting flange is formed almost completely or completely enclosing the pump housing.

The shield housing encloses the pump housing at least partially and the connection flange almost completely or completely in the axial direction. Almost completely means that the shield housing encloses the connection flange more than 75%, preferably more than 90%. The shield housing encloses the pump housing advantageously at least partially and the connection flange completely in the radial direction.

The pump according to the invention can be used in applications with high magnetic field strengths, since a shield of the vacuum pump is generated, in which no eddy current effects on the rotor lead to a thermal overload of the pump. The pump housing itself is usually made of materials with poor or absent shielding properties. The shielding is achieved by the shield housing provided according to the invention, which is formed at least partially and the connecting flange almost completely or completely enclosing the pump housing.

The vacuum pump according to the invention has the advantage that the screen housing, by virtue of the fact that it almost completely or completely encloses the fastening flange, can be formed abutting the recipient or with a distance of only a few millimeters, that is to say essentially up to the recipient's custom housing. so that the shield is effective up to the recipient and no weak point is created in the flange mounting.

According to a further advantageous embodiment of the invention, the shield housing has a mounting flange for connection to the recipient. This ensures that the shield housing is arranged directly on the recipient and thus no gaps in the shield arise, through which the external magnetic field can penetrate and cause eddy current effects on the rotor.

According to a further advantageous embodiment of the invention it is provided that the shield housing for connection to the recipient blind holes and / or through holes. These holes can be thread-free or formed with an internal thread.

Characterized in that the shield housing has the mounting flange for attachment to the recipient with the corresponding blind holes and / or through holes, the shield housing has an outer diameter in the region of the mounting flange, which corresponds to the usual outer diameter of the mounting flange of the pump housing.

This ensures that the size of the vacuum pump with pump housing and shield housing is not larger than the pump housing belonging to the prior art. This embodiment has the advantage that the screen housing does not lead to an increase in the installation space and thus not to collisions in the system.

The shield is thus designed according to the invention such that in the shield housing, the attachment function of the housing flange is integrated.

According to an advantageous embodiment of the invention, the shield housing on the recipient side has a flange. This mounting flange is, as already stated, advantageous to connect the shield housing and not the pump housing to the recipient.

According to a further advantageous embodiment of the invention it is provided that the pump housing has a housing portion in which at least one rotor of the vacuum pump is arranged and that the housing portion is arranged completely in the shield housing.

This embodiment according to the invention has the advantage that not only the mounting flange of the pump housing is enclosed by the screen housing, but also that the entire area of the pump housing, which accommodates the rotor, is enclosed by the screen housing. This in turn means that the entire rotor is indirectly enclosed by the screen housing, so that the described eddy current effects on the rotor do not occur. Indirect means that the shield housing encloses the pump housing and the pump housing encloses the rotor.

According to a further advantageous embodiment of the invention it is provided that the shield housing is constructed in one piece or in several parts. The shield housing can be built in one piece and the vacuum pump is connected to the Pump housing inserted into the shield housing. The shielding housing may also be formed divided along one or more generatrices, so that the shielding housing can be arranged around the pump housing, for example also in the region of connection flanges.

A further advantageous embodiment of the invention provides that at least one O-ring is arranged between the shield housing and the pump housing.

The O-ring can have a sealing effect. In the first place, however, it is provided that the at least one O-ring serves for the mechanical stabilization, that is to say the damping. The O-ring acts primarily tolerance-compensating.

According to a further advantageous embodiment of the invention it is provided that at least one CF seal is provided for sealing the pump housing and / or the screen housing relative to the recipient. A CF seal is characterized by the fact that both flange partners are made of stainless steel, that between the flanges a copper ring seal is arranged, that both flanges have a (stainless steel) cutting edge, which press into the copper ring and thus form the seal ,

This seal, which can be arranged in the high vacuum region, without outgassing, serves to seal the connection area between the pump housing and the recipient and / or between the shield housing and the recipient in order to ensure a vacuum-tight connection.

According to a particularly preferred embodiment of the invention, the flange of the screen housing is a standard flange educated. This means that the outer dimension of the mounting flange of the screen housing, for example, a standard flange attachment, such as ISO-F or ISO CF corresponds, which due to the high wall thickness of the shield, the use of the pump in very high magnetic field strengths without significant impact on the temperature behavior of the pump becomes possible.

If the shielding were to be additionally arranged around the standard flange of a pump housing, very large and thus more expensive output parts for the shielding would result.

Advantageously, a shield with ISO-F flange mounting to an ISO-K housing, similar to an ISO-F-Überwurfflansch adapted. This makes it possible to retrofit a pump with standard ISO-K flange with a shield housing according to the invention and then to assemble with an ISO-F flange connection.

The shield housing according to the invention can be made of a pipe material with a suitable inner and outer diameter with little effort.

According to a further advantageous embodiment of the invention, the shield housing is at least partially formed of a magnetic field shielding material. It is advantageously provided that the shield housing is at least partially formed of ferromagnetic material.

For example, soft iron, nickel or cobalt can be used as the material, with iron being the least expensive material and thus being used with preference.

For example, it is possible to manufacture the shield housing from inexpensive structural steel.

According to a further advantageous embodiment of the invention, it is provided that a housing section is provided, in which an electronics and / or a motor is / are arranged, and that the housing section is at least partially disposed in the screen housing and / or in a further screen housing.

This embodiment has the advantage that the motor and / or the electronics are shielded from an externally applied magnetic field, which also has an advantageous effect on the operation of the vacuum pump.

According to a particularly preferred embodiment, the vacuum pump is designed as a turbomolecular pump. These pumps operate at particularly high speeds. These pumps are operated at speeds up to 90,000 revolutions per minute and the shielding according to the invention has been found to be particularly advantageous in these pumps.

The use of the screen housing according to the invention is also possible with vacuum pumps with additional taps (split-flow pumps). The shield housing has corresponding openings for these taps. However, these openings are not detrimental to a suitable dimensioning for the shielding effect.

The shielding housing must basically have no sealing function, whereby the demands on the surface quality are only small. Since the shield has no contact with the vacuum area, materials can be used be otherwise unsuitable for the vacuum technology, but which are inexpensive.

However, it is not excluded that the shield housing has a sealing function.

Since the shield surrounds at least the entire area of the rotor which is equipped with rotor disks, the shield housing contributes to housing safety. The pump housing can therefore be made thin-walled or from a smaller output part, whereby a significant cost savings in the manufacture of the vacuum pumps occurs.

Also by the fact that the mounting flange is formed for connection to the recipient of the shield housing, the flange of the pump housing can be formed with a significantly smaller diameter, whereby the pump housing can be made of an output member with a much smaller diameter. Since the starting component (blank) has a significantly smaller diameter, the cost of this component compared to the prior art components for the vacuum pumps are significantly reduced.

Due to the mass of the shield, the vibration behavior of the vacuum pump can be positively influenced. In addition, the connection between the shield housing and the pump housing can be designed such that it has a damping effect.

Fig. 1

eine Vakuumpumpe mit Schirmgehäuse in perspektivischer Ansicht;

Fig. 2

einen Längsschnitt durch die Pumpe gemäß Fig. 1;

Fig. 3

einen Teilschnitt durch die Pumpe gemäß Fig. 1;

Fig. 4

ein zweites Ausführungsbeispiel einer Vakuumpumpe mit Schirmgehäuse in perspektivischer Ansicht;

Fig. 5

einen Längsschnitt der Pumpe gemäß Fig. 4;

Fig. 6

einen Teilschnitt der Pumpe gemäß Fig. 4;

Fig. 7

einen Längsschnitt durch einen ISO-KF-Flansch mit Pratzen;

Fig. 8

einen Längsschnitt durch einen ISO-KF-Flansch mit ISO-F-Überwurfring;

Fig. 9

einen Längsschnitt durch einen ISO-F-Flansch;

Fig. 10

einen Längsschnitt durch einen CF-Flansch;

Fig. 11

ein geändertes Ausführungsbeispiel.

Further features and advantages of the invention will become apparent from the accompanying drawings, in which several embodiments of a vacuum pump according to the invention are shown by way of example only. In the drawing show:

Fig. 1

a vacuum pump with screen housing in perspective view;

Fig. 2

a longitudinal section through the pump according to Fig. 1 ;

Fig. 3

a partial section through the pump according to Fig. 1 ;

Fig. 4

a second embodiment of a vacuum pump with screen housing in a perspective view;

Fig. 5

a longitudinal section of the pump according to Fig. 4 ;

Fig. 6

a partial section of the pump according to Fig. 4 ;

Fig. 7

a longitudinal section through an ISO-KF flange with claws;

Fig. 8

a longitudinal section through an ISO-KF flange with ISO-F-coupling ring;

Fig. 9

a longitudinal section through an ISO-F flange;

Fig. 10

a longitudinal section through a CF flange;

Fig. 11

a modified embodiment.

The Fig. 1 to 3 show a turbomolecular pump 1, which has a pump housing 2 and a screen housing 3.

In a separate housing 4 electronics is housed. The engine (not shown) is disposed in a motor housing 33. The vacuum pump 1 has a turbomolecular pumping stage 5 and a Holweckpumpstufe 6. The pumping stages are only in Fig. 3 shown.

The shielding housing 3 has an axial longitudinal extent, such that the Holweckpumpstufe 6 and the turbomolecular pumping stage 5 including the flange 9 of the vacuum pump 1 are completely enclosed in the axial direction of the screen housing 3. This ensures that, when the vacuum pump 1 is used in the region of high magnetic field strengths, there is a shielding of the rotor 7, eddy current effects on the rotor 7, which can lead to thermal overloading of the vacuum pump 1, are avoided.

The rotor 7 consists of a shaft 10 which carries rotor blades 11 in the region of the turbomolecular pump stage 5. The rotor blades 11 engage in stator blades 12, which are fastened to the pump housing 2. The Holweckpumpstufen 6 have rotating, arranged on the shaft 10 pump-active structures 13 and disposed on the stator pump-active structures 14.

The shield housing 3 takes over with the flange 8, the attachment function to the recipient. For this purpose, the shield housing 3 has the flange 8, which is designed as an ISO standard flange.

In the present case, the flange 8 is designed as an ISO-F flange.

The in the Fig. 1 to 3 illustrated vacuum pump 1 has a mounting flange 9 which is formed as arranged within the screen housing 3 flange 9. The attachment to the recipient is done by the ISO-F flange on the shield housing 3. The connection of the shield housing 3 to the pump flange is carried out as in the ISO-F-Überwurfflansch. The outer diameter of the screen housing 3 is constant over the entire axial length.

Between the pump housing 2 and the screen housing 3, an O-ring 30 is provided. The O-ring 30 has no sealing function, but serves primarily as a tolerance-compensating and for damping between the pump housing 2 and the screen housing. 3

In the 4 to 6 a vacuum pump 1 is shown, which has a pump housing 2 and a screen housing 3. The shielding housing 3 has a flange 8, in which fastening screws 16 can be arranged in holes 17 provided for this purpose. For sealing against a recipient beyond a CF seal 18 is provided.

The vacuum pump 1 also has an unshielded electronics housing 4.

The vacuum pump 1 has an inlet 19 and an outlet 20. The inlet 19 is connected to a recipient, not shown.

In the 4 to 6 For better clarity, the pump structure consisting of rotor and stator is not shown. However, it may have the same or similar construction as it has in the Fig. 1 to 3 is shown.

Also in the 4 to 6 illustrated vacuum pump 1 realized via the mounting flange of the screen housing the attachment to the recipient. The cutting edge of the CF seal 18 is arranged on the pump housing 2.

As in Fig. 5 shown, the screen housing 3 has an outer diameter A, while the pump housing 2 has an outer diameter B. If, as in the prior art, the mounting flange of the pump housing 2 is designed as a standard flange, the pump housing 2 has an outer diameter A in order to be able to be connected to a standardized standard connection of a recipient. This means that the blank, from which the pump housing 2 is manufactured, must have a diameter A. The pump housing 2 is rotated, for example, from the blank. The blank must have an outer diameter corresponding to the largest diameter of the finished pump housing 2.

Because the fastening function according to the invention is taken over by the shielding housing 3, the shielding housing 3 now has an outer diameter A, while the pump housing has a maximum outer diameter B. As a result, a blank can be used which has an outer diameter B. Since the pump housing 2 is usually made of stainless steel, a reduction in the outer diameter of the blank to a considerable extent saves costs.

Since the shield housing 3 usually has no sealing function, the requirements for the surface quality are only small. At the same time relatively inexpensive material can be used for the screen housing 3, since only the magnetic field shielding effect be given got to. This effect meets, for example, simple structural steel, since this is ferromagnetic.

Fig. 7 shows a recipient 21, which is secured to the screen housing 3 with an ISO-K flange with claws. About screws 23, which engage in threaded holes 17 of the screen housing 3, a flange 24 of the recipient 21 with the flange 8 of the screen housing 3 is releasably firmly connected.

For sealing, an O-ring seal 25 is provided between the flange 9 of the pump housing 2 and the flange 24 of the recipient. Advantageously, a centering ring 31 with O-ring 25 is used for this purpose. In addition, an O-ring seal 34 is provided between the shield housing 3 and the pump housing 2.

Fig. 8 shows a further mounting option with a coupling ring 26 (ISO-F). The coupling ring is arranged on the flange 24 of the recipient 21. Screws 23 engage through the coupling ring 26 in holes 17 of the flange 8 of the screen housing 3 and thus connect the pump housing 2 with the recipient 21. Between the flange 9 of the pump housing 2 and the flange 24 of the recipient is an O-ring seal, such as Example, a centering ring 31 with O-ring seal 25 is arranged.

In addition, an O-ring seal 34 is provided between the shield housing 3 and the pump housing 2.

Fig. 9 shows an ISO-F flange 27 which is disposed on a recipient 21. The ISO-F flange 27 is fastened with screws 23 on the screen housing 3, which engage in holes 17. The holes 17 are arranged in the flange 8. In the shield housing 3, the pump housing 2 arranged. Between the pump housing 2 and the screen housing 3, an O-ring seal 34 is provided. Between the ISO-F flange 27 and the pump housing 2, a centering ring 31 and an O-ring seal 25 are arranged.

Fig. 10 shows a CF flange 28 which is disposed on the recipient 21. The shield housing 3 has the flange 8 with holes 17. In the threaded holes 17 engage screws 23 which connect the CF flange 28 with the screen housing 3. Between the flange 9 of the pump housing 2 and the CF flange, a CF seal 18 is arranged.

The shield housing 3 is advantageously designed such that the shield housing 3 takes over the attachment function of the housing flange. The outer dimensions in the flange area may correspond to those of a standard flange mounting such as ISO-F or ISO-CF. It is possible to adapt an ISO F flange mount shield housing 3 to an ISO K housing, similar to an ISO F male flange. In this way it is possible to retrofit standard ISO-K pumps with a screen housing 3 according to the invention and to mount them with an ISO-F flange connection.

Fig. 11 shows the vacuum pump 1, as in Fig. 2 is shown. The same parts are provided with the same reference numbers. Opposite the Fig. 2 an electronics housing 4 is additionally arranged in a shield housing 29 in order to achieve additional shielding of the electronics. Alternatively or additionally, it is also possible to arrange a motor housing 33 within a screen housing 32.

reference numerals

1

Turbo molecular pump

2

pump housing

3

screen housing

4

motor housing

5

Turbo molecular pump stage

6

Holweckpumpstufe

7

rotor

8th

Flange of the screen housing 3

9

Flange of the pump housing 2

10

wave

11

rotor blades

12

stator

13

Pump-active structures of Holweckpumpstufe

14

Pump-active structures of Holweckpumpstufe

16

mounting screws

17

drilling

18

CF seal

19

inlet

20

outlet

21

recipient

22

claws

23

screw

24

flange

25

O-ring seal

26

Coupling ring

27

ISO-F flange

28

CF flange

29

screen housing

30

O-ring

31

centering

32

screen housing

33

motor housing

34

O-ring seal

A

outer diameter

B

outer diameter

Claims (13)

Vacuum pump with a pump housing, which has a fastening flange for connection to a recipient,
characterized in that a screen housing (3) is provided, which at least partially and the mounting flange (9) is formed almost completely or completely enclosing the pump housing (2). Vacuum pump according to claim 1, characterized in that the screen housing (3) has a fastening flange (8) for connection to the recipient (21). Vacuum pump according to claim 1 or 2, characterized in that the screen housing (3) for connection to the recipient (21) blind holes and / or through holes (17). Vacuum pump according to claim 3, characterized in that the bores (17) are formed thread-free or with internal thread. Vacuum pump according to one of the preceding claims, characterized in that the pump housing (2) has a housing portion in which at least one rotor (7) of the vacuum pump (1) is arranged, and in that the housing portion is arranged completely in the screen housing (3). Vacuum pump according to one of the preceding claims, characterized in that the screen housing (3) is constructed in one piece or in several parts. Vacuum pump according to one of the preceding claims, characterized in that between the screen housing (3) and the pump housing (2) at least one O-ring (30) is arranged. Vacuum pump according to one of the preceding claims, characterized in that at least one CF seal for sealing the pump housing (2) and / or the screen housing (3) relative to the recipient (21) is provided. Vacuum pump according to one of the preceding claims, characterized in that the flange (8) of the screen housing (3) is designed as a standard flange attachment. Vacuum pump according to one of the preceding claims, characterized in that the screen housing (3) is at least partially formed from a magnetic field shielding material. Vacuum pump according to one of the preceding claims, characterized in that the screen housing (3) is at least partially formed from a ferromagnetic material. Vacuum pump according to one of the preceding claims, characterized in that a housing section (4) is provided in which an electronics and / or a motor is / are arranged, and that the housing section (4) at least partially in the shield housing (3) and / / or in a further shield housing (29) is arranged. Vacuum pump according to one of the preceding claims, characterized in that the vacuum pump (1) is designed as a turbomolecular pump.

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