EP3786457B1 - Rotor arrangement for a vacuum pump, vacuum pump and method for manufacturing the same - Google Patents

Description

The invention relates to a rotor arrangement for a vacuum pump, in particular for a turbomolecular pump, a vacuum pump and a method for producing such a rotor arrangement.

Vacuum pumps, such as turbomolecular pumps, are used in various areas of technology, such as in semiconductor production, to create a vacuum that is necessary for the respective process. A turbomolecular pump generally comprises a rotor arrangement which, during operation of the turbomolecular pump, rotates at a very high speed, which is typically above 10,000 revolutions per minute, in relation to a stator or a housing of the turbomolecular pump.

Since the rotor arrangement thus has a very high kinetic energy during operation of the turbomolecular pump, in the event of a so-called "rotor crash", in which the rotor arrangement blocks for a short time, for example, an extremely high torque can act on the housing of the turbomolecular pump and, via this, on to the entire vacuum system be transferred, in which the turbomolecular pump is located. In the event of a rotor crash, there is consequently a considerable risk of destruction and injury in the vicinity of the turbomolecular pump.

This problem is particularly relevant in the case of magnetically levitated turbomolecular pumps if they have a bell-shaped rotor arrangement in order to accommodate the magnetic bearing and possibly also a drive motor of the rotor arrangement in a cavity within the bell-shaped rotor arrangement. In the event of a rotor crash, such a bell-shaped rotor arrangement can suddenly break apart into a few parts, each of which has a very high kinetic energy. Such a breaking apart of the rotor assembly is also referred to as a "burst".

From the JP 2012 145043 A a rotor arrangement with the features according to the respective preamble of claim 1 or 3 and a method with the features according to the respective preamble of claim 9 or 11 are known.

the DE 20 2013 006 436 U1 describes a rotor arrangement for a vacuum pump with a rotor body which is wrapped with an armoring tape on its outer circumference.

In the EP 3 085 964 A1 describes a rotor assembly for a vacuum pump in which a rotor body has reinforcement rings attached thereto by a cross-press connection.

An object of the invention is to provide a rotor assembly for a vacuum pump, a vacuum pump and a method of manufacturing a rotor assembly, in which improved strength of the rotor assembly against breakage is easily achieved. Furthermore, the hazard in the vicinity of the vacuum pump should also be reduced in the event of the rotor arrangement breaking apart.

This object is solved by the subject matter of the independent claims.

A rotor arrangement according to the invention for a vacuum pump, in particular for a turbomolecular pump, has a rotor body which is wrapped at least once completely around the axis of rotation with an armoring strip on its outer circumference.

The presence of the armor band on the outer circumference of the rotor body improves the resistance of the rotor assembly to breaking apart. This reduces the risk of danger in the vicinity of the vacuum pump.

In the event of the rotor assembly breaking apart or "bursting", the armor strip ensures that the individual parts of the rotor assembly are still held together for a certain period of time and the burst is thus extended over a longer period of time. As a result, the kinetic energy of the rotor arrangement or a corresponding torque is also transmitted to a housing of the vacuum pump over a longer period of time, which reduces the total torque exerted on the vacuum pump and reduces the risk of the vacuum pump tearing off, for example pump flange exists. Overall, therefore, the risk of destruction and injury in the area surrounding the vacuum pump is reduced by the armor strip, even in the event of a rotor crash or burst.

In addition, the wrapping of the rotor body with the armoring strip can be applied to the outer circumference of the rotor body in a simple manner, and no prefabricated tubes or rings have to be produced, which are shrunk onto the rotor body, for example, as armor. The reinforcement of the rotor body can thus be achieved in a cost-effective manner by means of the reinforcement strip.

The rotor assembly includes at least two pumping stages spaced along the axis of rotation and each having active pumping elements located on the outer periphery of the rotor body. The rotor body is also at least once completely circumferential on its outer circumference at a plurality of positions which are different from one another in the axial direction, with respective wrapped in armor strips. The number of windings of the respective armoring tapes is different. This applies generally, ie regardless of whether the armor strips are arranged in different intermediate spaces between individual pumping stages or generally at a number of different axial positions.

Furthermore, the rotor body is bell-shaped and has an inner space, the cross section of which increases perpendicularly to the axis of rotation in the axial direction, starting from a high-vacuum side of the rotor arrangement. Since the cross section of the inner space of such a bell-shaped rotor body increases in the axial direction, the outer circumference of the rotor body also increases in the same direction. The wrapping by means of an armoring strip to produce an armoring of the rotor body is particularly advantageous in such a bell-shaped rotor, since otherwise when using armoring tubes or armoring rings, a large number of armorings with different diameters would first have to be produced. When the armoring tape is wrapped around, the outlay for producing the armoring is consequently reduced in the case of bell-shaped rotor bodies. In this case, the rotor body is wrapped with an armoring strip in each case in one or more intermediate spaces between pump stages which are furthest away from the high-vacuum side of the rotor arrangement.

Alternatively, the rotor assembly includes more than two pumping stages spaced along the axis of rotation and each having pumping active elements located on the outer periphery of the rotor body. In each case one armoring strip is arranged in at least two intermediate spaces, which extend in the axial direction between the two pumping stages, and is wound around the rotor body.

By wrapping the rotor body with the armoring tape in several spaces between the pumping stages, the strength of the rotor assembly can be improved in an efficient manner, since the rotor assembly can initially be manufactured without armoring tape and the spaces between the pumping stages are then accessible for wrapping with the armoring tape. The number of spaces in which the rotor body is to be wrapped with the armoring tape is selected based on a rated speed of the rotor assembly. The reinforcement of the rotor body can thus be flexibly adapted to the conditions during operation of the vacuum pump by wrapping it in a number of intermediate spaces between the pump stages. Furthermore, the number of windings of a respective armoring strip is selected on the basis of the nominal speed of the rotor arrangement.

The number of windings or layers of the armoring strip can thus be increased at those points along the outer circumference of the rotor body that are considered to be particularly critical for a burst of the rotor body or when such a burst occurs, for example at points with a large outer circumference of the rotor body or larger Dimensions. The entire thickness of the reinforcement can thus be flexibly varied along the outer circumference of the rotor body or in the axial direction along the axis of rotation and adapted to the expected risk of a burst.

Advantageous developments of the invention are specified in the dependent claims, the description and the drawings.

The armoring strip can include a carbon fiber reinforced plastic (CFRP). The carbon fibers or carbon fibers of the CFRP are embedded in a plastic matrix, which can include, for example, epoxy resin, duroplastics or thermoplastics. The fibers can be integrated into the plastic matrix in such a way that a flexible reinforcement band is present overall. which can be unrolled in a similar way to packing tape when the armoring tape is wrapped around the rotor body. The carbon fiber reinforced plastic (CFRP) has a low mass despite high rigidity. The strength of the rotor body and the rotor arrangement can be improved overall by integrating the CFRP into the armoring strip.

The armoring strip can also be wound at least once around the outer circumference of the rotor body in a plurality of layers and/or next to one another at a plurality of positions which differ from one another in the axial direction. Different axial positions can be dictated by different clearances between pump stages. But this is not mandatory. A plurality of armoring strips can also be arranged in a single space between two immediately consecutive pumping stages on different axial pumping stages or on a rotor body without pumping stages or on a region of a rotor body comprising no pumping stages.

In addition, it can be provided that the rotor body is wrapped helically or helically with one or more layers of the armoring strip in one or more axial areas. An armoring strip does not therefore have to be in just one axial position.

In addition, the rotor body can be designed in one piece. With such a rotor body, the wrapping with the armoring strip is a simple and cost-effective way of actually attaching an armoring to the rotor body. For example, fitting armor tubes or rings in the spaces between pumping stages of a one-piece rotor is extremely difficult, if not impossible.

According to a further embodiment, the armoring strip can be self-adhesive and/or, after being wrapped around it, can be connected to the rotor body by exposure to an elevated temperature that is greater than the ambient temperature. In the case of a self-adhesive armoring strip, the wrapping of the rotor body involves particularly little effort, since no connecting means, such as adhesive, have to be used between the armoring strip and the rotor body. A particularly strong connection between the armoring strip and the rotor body can also be produced by the effect of an increased temperature, for example by "baking" of the armoring strip with the rotor body in an oven. The type of connection - e.g. self-adhesive or "baking" - can depend on the respective design of the armoring strip.

The invention also relates to a vacuum pump, which is in particular a turbomolecular pump and which has a rotor arrangement as described above.

A further object of the invention is a method for producing a rotor arrangement for a vacuum pump, in which the outer circumference of the rotor body is wrapped at least once completely around the axis of rotation with an armoring strip.

Furthermore, the outer circumference of the rotor body is wrapped at least once completely around the circumference at a plurality of positions which differ from one another in the axial direction with respective armoring strips. The number of windings of the respective armoring tapes is different.

Alternatively or additionally, a number of windings of a respective armoring strip is selected depending on a nominal speed of the rotor arrangement. The strength of the reinforcement is thus adapted to the rated speed of the rotor arrangement, so that on the one hand the reinforcement is strong enough and on the other hand no unnecessary additional mass is applied to the rotor body by too strong a reinforcement.

If the rotor arrangement comprises more than two pump stages, an armoring strip is wound around the rotor body in at least two and in particular in all intermediate spaces which extend in the axial direction between the pump stages.

With such a method, reinforcement can be produced on the rotor body in a simple and cost-effective manner, so that its resistance to a burst is improved. The effort involved in producing the reinforcement is reduced when the reinforcement tape is wrapped around it, in particular in comparison to reinforcement tubes or reinforcement rings because the diameter of such reinforcement tubes or reinforcement rings has to be precisely adapted to the diameter of the rotor body, and such an adjustment is not necessary when the reinforcement tape is wrapped around it . The advantages mentioned above and the disclosure, which are described for the rotor arrangement according to the invention and its embodiments, also apply mutatis mutandis to the method according to the invention.

The armoring strip preferably comprises a carbon fiber reinforced plastic (CFRP).

In one embodiment of the method, the armoring strip can be wound at least once around the outer circumference of the rotor body in a plurality of layers and/or next to one another at a plurality of positions that differ from one another in the axial direction. The wrapping of the rotor body with several layers and/or at different points in the axial direction along the rotor body enables flexible adaptation of the reinforcement with regard to its position and thickness to the operating properties of the rotor arrangement and the vacuum pump.

According to a further embodiment of the method, the armoring strip can be wrapped around the rotor body as a self-adhesive strip and/or, after wrapping, can be connected to the rotor body by exposure to an elevated temperature that is greater than the ambient temperature. If the armoring strip is self-adhesive, there is no additional effort to connect the armoring strip to the rotor body, for example by means of adhesive, while the connection between the armoring strip and the rotor body can be made alternatively or additionally strengthened after the wrapping by the effect of an increased temperature.

Fig. 1A

eine erfindungsgemäße Rotoranordnung und

Fig. 1B

einen Ausschnitt der in Fig. 1A gezeigten Rotoranordnung.

The invention is described below by way of example using an advantageous embodiment with reference to the attached figures. They show, each schematically:

Figure 1A

a rotor arrangement according to the invention and

Figure 1B

a section of the in Figure 1A shown rotor assembly.

Figure 1A shows a possible example of a rotor arrangement 11 according to the invention for a turbomolecular pump. During operation of the turbomolecular pump, the rotor assembly 11 rotates at a speed that is greater than 10,000 revolutions per minute, for example, about an axis of rotation 13. The rotor assembly 11 has a rotor body 15, which is bell-shaped, so that the rotor assembly 11 includes an interior 17 , whose cross section perpendicular to the axis of rotation 13 in the axial direction starting from a high-vacuum side of the rotor assembly 11 - in Figure 1A so from top to bottom - increases. The high-vacuum side of the turbomolecular pump, for which the rotor assembly 11 is intended, is located in Figure 1A above. Due to the bell-shaped design of the rotor body 15, the rotor assembly 11 is also referred to as a bell-shaped rotor.

On the outside of the rotor body 15, the rotor arrangement 11 comprises a plurality of pump stages 19, which comprise rotor disks 21 as active pumping elements. The rotor disks 21 together with the respective stator disks (not shown) form a respective pumping stage of the turbomolecular pump for which the rotor arrangement 11 is provided. Between the rotor disks 21 there is in each case an intermediate space 23 in which a stator disk is present in each case after the rotor arrangement 11 has been installed in the turbomolecular pump.

A reinforcement 27 is attached to an outer circumference 25 of the rotor body 15 in the intermediate space 23 between the two lowest rotor disks 21 . The reinforcement 27 comprises three layers of a reinforcement strip 29 which is wound around the outer circumference 25 of the rotor body 15 three times completely around the axis of rotation 13 .

Figure 1B shows an enlarged section of Figure 1A , in which the three layers of the armoring strip 29 in the intermediate space 23 between the two lowest rotor disks 21 can be seen. In the present embodiment the three layers of the armoring strip 29 form the armoring 27 on the outer circumference 25 of the rotor body 15 between those two rotor disks 21 which are furthest away from the high-vacuum side of the rotor arrangement 11 and in their intermediate space 23 the outer diameter of the rotor body 15 is larger than in all other intermediate spaces 23 is. The reinforcement 27 is thus located in a region of the rotor body 15 in which it has a greater moment of inertia in relation to the other intermediate spaces 23 . It is advantageous to provide the reinforcement 27 between the two lowest rotor discs 21, since the reinforcement 27 at this point improves the strength of the rotor body 15 against breaking apart or a burst the most.

While the reinforcement 27 in the embodiment of Figures 1A and 1B shown only between the two lowest rotor disks 21, the reinforcement 27 can also be arranged in further intermediate spaces 23 between the rotor disks 21 by winding one or more layers of the armoring strip 29 in the respective intermediate space 23 around the outer circumference 25 of the rotor body 15. It is also possible for a respective reinforcement 27 with at least one layer of the reinforcement strip 29 to be attached in all the intermediate spaces 23 between the rotor disks 21 .

The reinforcement tape 29 consists of a flexible plastic material that is self-adhesive and is unrolled in a manner similar to a package adhesive tape. The armoring strip 29 comprises a carbon fiber reinforced plastic (CFRP) in which fibers are embedded in a plastic matrix in order to increase the strength of the armoring strip 29 . To produce the reinforcement 27 , the CFRP reinforcement strip 29 is wound three times completely around the axis of rotation 13 around the outer circumference 25 of the rotor body 15 . The strength of the rotor arrangement 11 is improved by the reinforcement 27 by means of the reinforcement strip 29, and there is less elongation under the centrifugal force at high speeds. As a result, the rotor arrangement 11 can achieve a higher nominal speed than a corresponding rotor arrangement without the reinforcement 27 .

If a rotor crash with the rotor body 15 breaking apart or a burst should nevertheless occur during operation of the turbomolecular pump, the fragments of the rotor body 15 are held together by the reinforcement 27 for a certain period of time, so that the entire period of time is extended over which the kinetic Energy or the torque of the rotor assembly 11 is transmitted to a housing of the turbomolecular pump or to the environment of the rotor assembly 11 and the turbomolecular pump. As a result, the torque that acts on the stator and the housing of the turbomolecular pump as a whole in the event of a rotor crash is reduced. The risk of injury and destruction in the event of a rotor crash is thus reduced by the reinforcement 27 by means of the reinforcement strip 29 .

Reference List

11

rotor arrangement

13

axis of rotation

15

rotor body

17

inner space

19

pump stage

21

rotor disk

23

space

25

outer perimeter

27

reinforcement

29

armor tape

Claims (14)

1. A rotor arrangement (11) for a vacuum pump, in particular for a turbomolecular pump, comprising a rotor body (15) which rotates about an axis of rotation (13) in the operation of the vacuum pump,

   wherein the rotor body (15) is bell-shaped and has an inner space (17) whose cross-section increases at a right angle to the axis of rotation (13) in the axial direction, starting from a high vacuum side of the rotor arrangement (11),

   wherein the rotor arrangement (11) comprises at least two pump stages (19) which are arranged spaced apart along the axis of rotation (13) and which each comprise pump-active elements (21) which are located at an outer periphery (25) of the rotor body (15), and

   wherein the rotor body (15) is wrapped around at the outer periphery (25), at a plurality of positions which differ from one another in the axial direction, by respective reinforcement bands (29) revolving at least once completely about the axis of rotation (13),

   characterized in that

   the rotor body (15) is wrapped around by a respective reinforcement band (29) in one or more intermediate spaces (23) between the pump stages which are the furthest away from the high vacuum side of the rotor arrangement (11), and

   the number of windings of the respective reinforcement bands (29) is different.
2. An rotor arrangement (11) in accordance with claim 1, wherein
   the number of windings of the respective reinforcement band (29) is selected in dependence on a nominal rotational speed of the rotor arrangement (11).
3. A rotor arrangement (11) for a vacuum pump, in particular for a turbomolecular pump, comprising a rotor body (15) which rotates about an axis of rotation (13) in the operation of the vacuum pump,

   wherein the rotor body (15) is wrapped around at its outer periphery by a reinforcement band (29) revolving at least once completely about the axis of rotation (13), and

   wherein the rotor arrangement (11) comprises more than two pump stages (19) which are arranged spaced apart along the axis of rotation (13) and which each comprise pump-active elements (21) which are located at the outer periphery (25) of the rotor body (15),

   characterized in that

   a respective reinforcement band (29) is wrapped around the rotor body (15) in at least two intermediate spaces (23) which extend in the axial direction between the pump stages (19),

   a number of windings of the respective reinforcement band (29) is selected in dependence on a nominal rotational speed of the rotor arrangement (11), and

   the number of intermediate spaces (23) in which the rotor body (15) is in each case wrapped around by the reinforcement band (29) is selected on the basis of the nominal rotational speed.
4. A rotor arrangement (11) in accordance with claim 3, wherein
   the rotor body (15) is bell-shaped and has an inner space (17) whose cross-section increases at a right angle to the axis of rotation (13) in the axial direction, starting from a high vacuum side of the rotor arrangement (11).
5. A rotor arrangement (11) in accordance with any one of the preceding claims, wherein
   a respective reinforcement band (29) is wrapped around the rotor body (15) in all the intermediate spaces (23).
6. A rotor arrangement (11) in accordance with any one of the preceding claims, wherein
   the respective reinforcement bands (29) are wrapped around the outer periphery (25) of the rotor body (15), in each case revolving completely at least once, in a plurality of layers and/or next to one another at a plurality of positions which differ from one another in the axial direction.
7. A rotor arrangement (11) in accordance with any one of the preceding claims, wherein
   the respective reinforcement band (29) is self-adhesive and/or is connected to the rotor body (15) after the winding around by an exposure to an increased temperature which is greater than the environmental temperature.
8. A vacuum pump, in particular a turbomolecular pump, comprising a rotor arrangement (11) in accordance with any one of the preceding claims.
9. A method of producing a rotor arrangement (11), in particular configured in accordance with any one of the claims 1 to 7, for a vacuum pump, in particular for a turbomolecular pump,

   wherein the rotor arrangement (11) has a rotor body (15) which rotates about an axis of rotation (13) in the operation of the vacuum pump,

   wherein the rotor body (15) is bell-shaped and has an inner space (17) whose cross-section increases at a right angle to the axis of rotation (13) in the axial direction, starting from a high vacuum side of the rotor arrangement (11), and

   wherein the rotor arrangement (11) comprises at least two pump stages (19) which are arranged spaced apart along the axis of rotation (13) and which each comprise pump-active elements (21) which are located at an outer periphery (25) of the rotor body (15),
   wherein the method comprises the rotor body (15) being wrapped around at the outer periphery (25), at a plurality of positions which differ from one another in the axial direction, by respective reinforcement bands (29) revolving completely at least once,

   characterized in that

   the rotor body (15) is wrapped around by a respective reinforcement band (29) in one or more intermediate spaces (23) between pump stages which are the furthest away from the high vacuum side of the rotor arrangement (11), and

   the number of windings of the respective reinforcement bands (29) is different.
10. A method in accordance with claim 9, wherein
    the number of windings of a respective reinforcement band (29) is selected in dependence on a nominal rotational speed of the rotor arrangement (11).
11. A method of producing a rotor arrangement (11), in particular configured in accordance with any one of the claims 1 to 7, for a vacuum pump, in particular for a turbomolecular pump,

    wherein the rotor arrangement (11) has a rotor body (15) which rotates about an axis of rotation (13) in the operation of the vacuum pump, and

    wherein the rotor arrangement (11) comprises more than two pump stages (19) which are arranged spaced apart along the axis of rotation (13) and which each comprise pump-active elements (21) which are arranged at the outer periphery (25) of the rotor body (15),
    wherein the method comprises

    the rotor body (15) being wrapped around at its outer periphery (25) by a reinforcement band (29) revolving at least once completely about the axis of rotation (13),

    characterized in that

    a respective reinforcement band (29) is wrapped around the rotor body (15) in at least two intermediate spaces (23) which extend in the axial direction between the pump stages (19),

    a number of windings of the reinforcement band (29) is selected in dependence on a nominal rotational speed of the rotor arrangement (11), and

    the number of intermediate spaces (23) in which the rotor body (15) is in each case wrapped around by the reinforcement band (29) is selected on the basis of the nominal rotational speed.
12. A method in accordance with any one of the claims 9 to 11, wherein the respective reinforcement bands (29) are wrapped around the outer periphery (25) of the rotor body (15), in each case revolving completely at least once, in a plurality of layers and/or next to one another at a plurality of positions which differ from one another in the axial direction.
13. A method in accordance with any one of the claims 9 to 12, wherein a respective reinforcement band (29) is wrapped around the rotor body (15) in all the intermediate spaces (23).
14. A method in accordance with any one of the claims 9 to 13, wherein the respective reinforcement band (29) is wrapped around the rotor body (15) as a self-adhesive tape and/or is connected to the rotor body (15) after the winding around by an exposure to an increased temperature which is greater than the environmental temperature.

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