DE2249985A1 - TURBOMOLECULAR PUMP - Google Patents

Description

LEYBOLD-HERAEUS GMBH. & CO.KG. Cologne-Bayental

Turbo molecular pump

The invention relates to a turbomolecular pump with a stator connected to the pump housing and with a Pumpenrofor, whose electric drive motor is located directly on the multiple bearing rotor shaft.

Turbomolecular pumps are already known for generating a vacuum or high vacuum, in which the pump rotor provided with blade rings is driven at a high speed in a stator also having blades. When the pump rotor runs up to the operating speed, which can be around 20,000 to 50,000 revolutions / MIn ₀ , vibration phenomena result, the occurrence of which is dampened by providing additional damping elements in the form of spring assemblies or the like at the bearing points in a known manner are. These allow self-centering of the rotor shaft to a certain extent.

When using a turbo molecular pump in connection with vibration- _{sensitive apparatus, such as Z 0} B ₀ electron microscopes, the damping of the vibrations due to the elastic mounting of the rotor shaft appears to be insufficient. To avoid foundation separations and special connections between the turbo molecular pump and the apparatus, it is therefore necessary to further suppress the vibrations triggered by the high speeds.

The object set is achieved according to the invention in that that the housing of the drive motor is in a flange part of the

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Pump housing is elastically mounted. This generally results in a double-elastic storage, since the Bearing points of the rotor shaft with advantageous damping spring packages or the like. Are provided. Such a turbo molecular pump generates only extremely low vibrations on the foundation.

In a further embodiment of the invention, it can be expedient be, the exact; utb drive motor in a recess of the Flange part with the help of rubber-elastic sealing elements to store, which form a vacuum seal «As the electric drive motor of the turbo molecular pump is advantageous forms a self-contained unit, the separation point between the motor housing appears in the area of the lower one Housing end and a recess in the flange of the pump housing as particularly useful. The sealing elements O-rings that are sealed in several planes can be advantageous.

In another expedient embodiment that can The housing of the drive motor is additionally or exclusively resiliently supported in a recess in the flange part be. An advantageous constructive solution for producing the resilient support can be constructed in this way be that the housing of the drive motor against mirror symmetry inclined pressure springs evenly distributed around the circumference is supported and with a rubber-elastic Seal lies in a recess of the flange part such a design results in a particularly soft suspension of the drive motor.

In an alternatively expedient design of the bearing, the housing of the drive motor can be in the form of a circular ring disk Membrane be connected to the flange part. Such a connection can also be made vacuum-tight.

Because the pressure difference between the interior of the pump housing and the ambient atmosphere a bias on the

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Depicts storage of the drive motor, it appears if necessary expediently to dispense with a seal between the drive motor and the flange part and this thereby to achieve that the protruding through the flange part of the pump housing to the side facing away from the rotor part of the Drive motor is covered with a cap, which is sealed with its edge part against the flange part of the pump housing is.

At. the formation of the elastic mounting of the drive motor In general, care should be taken to ensure that in each permissible The deflection of the pump rotor relative to the stator is free remains movable. It therefore appears expedient to deflect the housing of the drive motor in the elastic mounting of the flange part.

Such a turbo molecular pump offers the advantage of extremely low amplification of vibrations as well as transmission to associated with it Components »

Exemplary embodiments of the invention are shown schematically in the drawing shown, from which further features of the invention result; show it:

FIG. 1 shows a longitudinal section through a turbomolecular pump according to the invention;

FIG. 2 shows a detail view with an alternative engine mount;

FIG. 3 shows a further detail illustration with compression spring support; the drive motor;

FIG. 4 shows a detail view with a membrane suspension of the drive motor.

In the embodiment according to FIG. 1, a turbo molecular pump can be seen, the pump housing 1 of which is closed by a flange part 2. Inside the pump housing 1 there is a stator 3. A rotor M- is via a multi-bearing rotor shaft 5 with an electric drive motor δ

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tied together. The bearings of the rotor shaft 5 are ball bearings 7, which have a certain radial displaceability due to elastic spring assemblies 8, whereby a self-centering of the Rotor and the rotor shaft and a certain suppression of the amplification of vibrations is achieved.

In a central recess 9 of the flange part 2 is a Housing 10 of the drive motor 6 in rubber-elastic sealing rings 11, 12 mounted by these elastic sealing rings 11, 12 is at the same time a vacuum-tight barrier between the forevacuum-side pump interior and the Ambient atmosphere achieved. An annular extension 13 and a threaded ring 14 are used to fasten the housing, which is screwed onto a threaded section 15 of the housing 10 is. The width of the gap opening a is dimensioned such that the rotor 4 also with a maximum deflection with respect to the stator 3 remained freely movable

In the embodiment of FIG. 2, the mounting of the housing 10 in the flange part 2 of the pump housing 1 is therefore an alternative designed that three rubber-elastic O-rings 16, 17, arranged in corresponding groove recesses 19, 20, 21 which are responsible for the elastic mounting and the vacuum seal ο The other components that are not explained in detail correspond to the embodiment according to FIG. 1.

While the embodiments described above, a seal of the interior of the pump housing by the Achieve mounting of the motor housing on the flange part is a vacuum-tight in the embodiments of Figures 3 and 4 Blocking off at the storage location is not provided. This results in the possibility of a softer design of the engine suspension.

Figure 3 shows the use of mirror-symmetrically inclined springs 22, 23 evenly distributed on the circumference, the in corresponding inclined blind holes 24, 2S

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and which rest against an inclined surface on an attachment part 26 and on an inclined ring 27. In the area of a central cylindrical plate 28 of the housing 10 there is a rubber-elastic O-ring 17 in the groove recess 20, corresponding to the design according to FIG The required vacuum seal is the protruding part of the drive motor 6 on the side facing away from the rotor covered with a cap 29, which is sealed with its edge part 30 by a rubber-elastic seal 31 with respect to the flange part 1 of the pump housing 1. In this embodiment, the suspension of the motor housing is relieved of the differential pressure and can - as already explained - be made softer.

Another, also pressure-relieved suspension is shown in Figure ¹ K Here - between the housing 10 of the drive motor and the flange part 2 there is a circular disk-shaped membrane 32, which is connected to the housing 10 of the drive motor and to the flange part 2 via threaded clamping rings 33, 3m, A larger threaded ring 35 can be set to limit the maximum deflectability in the area of the suspension of the motor Edge part 30 and the rubber-elastic seal brings about a seal with respect to the flange part 2,

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Claims (1)

- ⁶ - 22A9PB E> PROTECTION APPROACH ο J turbo molecular pump with one connected to the pump housing Stator and a pump rotor, whose electric drive motor is directly on the multiple mounted rotor shaft, characterized in that the housing. (10) of the drive motor (6) in a flange part (2) of the pump housing (1) is elastically mounted 2 "Turbo molecular pump according to claim 1, characterized marked, that the housing (10) of the drive motor (6; in a Recess (9) of the flange part (2) with. With the help of rubber-elastic sealing elements (Ii, 12, 16, 17, ιδ) stored which form a vacuum seal. 3. Turbo molecular pump according to claim 2, characterized in that the sealing elements are sealing in several planes O-rings (16, 17, 18) are * 4. Turbo molecular pump according to claim 1, characterized in that that the housing (10) of the drive motor (6) is resiliently supported in a recess (9) in the flange part (2) is. 5. Turbo molecular pump according to claim 4, characterized in that that the housing (10) of the drive motor (6) against mirror-symmetrical inclined, evenly distributed on the circumference Compression springs (22, 23) is supported and with a rubber elastic Seal (17) is inserted into a recess (9) in the flange part (2). 6. Turbo molecular pump according to claim 1, characterized in that the housing (10) of the drive motor (6) has a circular disk-shaped membrane (32) with the flange (2) of the pump housing (1) is connected = 0 98 1 6/0 1 8 8 BATH ORIGINAL 22A9985 7. turbo molecular pump according to one of claims 4, 5 or 6, characterized in that the pump housing (1) through the flange part (2) to the side facing away from the rotor protruding parts of the drive motor (6) is covered with a cap (.29), which with its edge part (30) opposite the flange part (2) of the pump housing (1) is sealed. 8. Turbomolecular pump according to claim 1, characterized in that that the articulation of the housing (10) of the drive motor (6) in the elastic bearing opposite the flange part (2) d * B pin housing (1) is limited in such a way that the pump rotor (* O remains freely rotatable in the stator (3). BATH ORIGINAL 409816/0188 Blank page