This application claims priority to German Patent Application No. 10 2015 217 670.3 filed on Sep. 15, 2015, the entirety of which is incorporated by reference herein.
The invention relates to a sealing element, a sealing system for a turbomachine, a turbomachine with a sealing system and a method for manufacturing a sealing element.
What is known from EP 1 114 241 B1 is a sealing element for a rotating fluid seal, wherein the sealing element has a sealing lip. A rubbing element is arranged in at least one location of the sealing lip in such a manner that the rubbing element projects radially and on one or two sides axially beyond the outer contour of the sealing lip. The rubbing element is a preformed element that is connected to the sealing lip in a form-fit and/or firmly bonded manner.
US 2007/0110562 A1 discloses a sealing element for a labyrinth seal that comprises a sealing lip and a plurality of U-shaped staples. The staples are arranged inside recesses at the sealing lip of the sealing element, so that they at least partially project beyond the outer contour of the sealing lip and form rubbing elements. Here, too, the rubbing elements are preformed elements that are connected to the sealing lip.
If installed in a sealing system according to the intended use, the sealing elements can come into contact at least partially with a run-in coating and therefore be subjected to high loads. These can be thermal loads as well as mechanical loads.
Especially a sealing lip of a sealing element is subject to these high loads. Excessive thermal and/or mechanical loads may result in the formation of cracks in the sealing lip.
It is therefore necessary to protect the sealing element, in particular the sealing lip, from these loads. This may for example be achieved by avoiding any large-area contact of the sealing lip with the run-in coating. In the state of the art, this is realized by arranging at least one rubbing element at the sealing lip, which facilitates broaching the run-in coating.
By broaching the run-in coating with the at least one rubbing element, the load on the entire sealing lip is reduced. It is mainly the rubbing element that comes into contact with the run-in coating; the sealing lip itself does not, for the most part. In this way, especially the rubbing element is subjected to high loads.
The rubbing elements that are known from the state of the art are arranged at the sealing lip in order to create a maximally effective abrasion effect if the sealing element is used in a sealing system and comes into contact with a run-in coating. Here, the abrasion effect is mainly created by the geometrical outer contour of the rubbing elements. Moreover, the rubbing elements have to be present in a prefabricated form before they can be connected to the sealing lip.
The present invention is based on the objective to provide a sealing element, a sealing system for a turbomachine, a turbomachine with a sealing system and a method for manufacturing a sealing element which are easy to manufacture and easy to use.
According to the invention, this objective is achieved through a sealing element with the features as described herein, a sealing system for a turbomachine with the features as described herein, a turbomachine with a sealing system with the features as described herein, and a method for manufacturing a sealing element with the features as described herein.
If installed in the sealing system of the turbomachine according to the intended use, the sealing element can be rotated around a rotational axis of the turbomachine. Here, the sealing element comprises a ring-shaped sealing lip, which can for example be configured in a circular manner. The ring-shaped sealing lip has a central point through which the rotational axis of the turbomachine extends if the sealing element is installed in the sealing system according to the intended use. Thus, the sealing element can rotate around the rotational axis of the turbomachine.
At least one recess is introduced into the sealing lip, with the at least one rubbing element being arranged therein. The rubbing element can for example be formed at the sealing lip itself. Here, the at least one rubbing element projects at least partially beyond the outer contour of the sealing lip, and namely in the axial direction, that is, along the rotational axis and/or in the radial direction, that is, perpendicular to the rotational axis of the turbomachine. The at least one rubbing element further has a plurality of layers of a rubbing material that comprises at least one basic material and abrasion particles. The abrasion particles are intermixed with the basic material. The abrasion particles and the basic material can have an increased thermal and mechanical resistance as compared to the rest of the material of the sealing element.
Further, the layers of the at least one rubbing element are configured at least partially in such a manner that the axial extension of the layers decreases with growing distance from the central point of the sealing lip. Thus, the at least one rubbing element at least in certain sections has an outer contour which tapers off in a cross-section in a convergent manner perpendicular to the circumferential direction of the sealing element. The layers project axially beyond the outer contour of the sealing lip, so that the layers form a contour at the exterior side. This structure can have an abrasive effect, for example.
In this way, it is possible to arrange the rubbing material at the sealing lip and thus form at least one rubbing element in a simple manner. The at least one rubbing element does not have to be present in the form of a prefabricated structural component, but can be formed at the sealing lip. In addition, the abrasion effect of the at least one rubbing element is increased through the composition of the rubbing material, comprising the basic material which is provided with abrasion particles. The surface of the at least one rubbing element does not undergo any further processing following the arrangement at the sealing lip. In this manner, a rough surface is created, in particular due to the layered configuration of the at least one rubbing element and/or due to the composition of the rubbing material.
As has already been described in the beginning, the sealing element—if installed according to the intended use in a sealing system—can come into contact at least partially with a static run-in coating and therefore be subjected to high loads. Through this rubbing element, these loads on the sealing lip of the sealing element can be reduced, since the contact surface of the sealing lip and the static run-in coating is reduced, for example by means of broaching the static run-in coating with the rubbing element. An increased abrasion effect of the rubbing element can facilitate the broaching of the static run-in coating.
What is understood by an abrasion effect is that—if the sealing element is installed according to the intended use in the sealing system—the at least one rubbing element creates abrasion in the static run-in coating that is arranged opposite to the sealing element in the radial direction. In this way, the static run-in coating is at least partially broached and the load on the other areas of the sealing element is reduced.
It is possible that the sealing lip has at least one recess, which is for example formed by a milling groove of the sealing lip, in order to receive the at least one rubbing element that is formed in a layered manner at least partially or completely inside the recess.
In another embodiment variant, the extension of at least some layers decreases along the circumferential direction with growing distance from the central point. In this manner, a convergent outer contour of the at least one rubbing element is created at least in certain sections in a cross-section perpendicular to the rotational axis.
In a further development, the at least one rubbing element has a separation layer for connecting to the sealing lip in order to facilitate a separation of the rubbing element from the sealing lip. In this way, a decoupling of the two elements can be achieved.
According to further embodiment variants, the at least one rubbing element can have a varying height along the circumferential direction of the sealing lip and/or can project at least partially beyond an outer contour of the sealing lip at least partially only on one side of the sealing lip along the axial direction.
In a further embodiment it is possible that the at least one rubbing element projects at least partially beyond the outer contour of the sealing lip in the axial direction only on one side of the sealing lip. Additionally or alternatively it is also possible that the surface of the at least one rubbing element is not subjected to any further processing following the arrangement at the sealing lip.
These configurations of the at least one rubbing element can increase the abrasion effect of the at least one rubbing element. In one embodiment variant, the abrasion effect can also be controlled in a targeted manner by means of the geometrical configuration of the rubbing element. In this way, it is possible to not only adjust the strength of the abrasion effect of the at least one rubbing element, but also the shape of the broached area of the run-in coating, such as for example the depth and/or the spatial orientation of the abrasion.
In a further embodiment, the rubbing material is arranged at the sealing lip by means of laser deposition welding (DLD, direct laser deposition). The laser deposition welding makes it possible to create local melting areas, for example in the sealing lip, into which the rubbing material can be introduced, for example in powder form, in order to connect the rubbing material with the sealing lip in a firmly bonded manner. It is also possible to create local melting areas in areas of the sealing element, in which rubbing material has already been arranged at the sealing lip, and to connect additional rubbing material in a firmly bonded to the already present rubbing material and thus to the sealing lip.
In one embodiment, the basic material of the rubbing material is the same as the material of the sealing lip either to a substantial percentage or completely. In particular, the basic material as well as the material of the sealing lip can be formed from a nickel-based alloy either to a substantial percentage or completely. In this manner, the arrangement of the rubbing material at the sealing lip can be facilitated. In one embodiment variant, the basic material can contain Inco718, Inco718+, Udimet, Waspaloy and/or RR1000, or can be comprised completely of these materials.
Further, the basic material can contain a nickel-based alloy, in particular 720Li, or can be comprised completely thereof. Details on such an 720Li alloy can be gathered from the following document: “Tensile Properties of Ni-Based Superalloy 720Li: Temperature and Strain Rate Effects” by K. Gopinath et al., Metallurgical and Materials Transactions A, Volume 39, No. 10, pages 2340-2350, DOI: 10.1007/s11661-008-9585-3.
In one embodiment variant, the abrasion particles are formed in a sharp-edged manner and/or have an increased hardness as compared to the basic material, in particular the abrasion particles can comprise materials of metal, ceramics and/or carbide. Thus, in a further development, the abrasion particles comprise cBN and/or TiC particles, for example.
The sharp-edged and/or hard abrasion particles facilitate broaching of the run-in coating.
In a further embodiment, the sealing lip can have multiple rubbing elements, which are for example arranged in a symmetrical manner along the circumference of the sealing lip. Thus, for example three rubbing elements can be arranged along the circumference of the sealing lip in such a manner that they are offset by respectively 120°, or four rubbing elements can be arranged along the circumference of the sealing lip in such a manner that they are offset by respectively 90°.
In one embodiment, the sealing lip can also have at least one groove at is circumference that is arranged at least in a substantially radial manner, in particular with grooves in the form of micro-slits having a width of between 50 μm and 300 μm. These grooves particularly serve the purpose of reducing thermal stress.
The objective is also achieved by a sealing system for a turbomachine with the features as described herein.
One embodiment of the sealing system has a static run-in coating, which is arranged opposite the at least one sealing element in the radial direction. Here, the at least one rubbing element of the at least one sealing element comes into contact with the static run-in coating during operation of the sealing system. Here, the at least one rubbing element broaches the static run-in coating at least partially. It is possible that the rubbing element comes into contact with the run-in coating as the first or as the only element of the sealing system.
In one embodiment variant, the sealing system can be formed as a labyrinth seal, in particular for an aircraft engine.
The objective is also achieved through a turbomachine, in particular an aircraft engine with the features as described herein.
The objective is also achieved through a method with the features as described herein, wherein the method comprises the following steps:
Exemplary embodiments are explained based on the following description and the Figures.
If the sealing element is installed in a sealing system of a turbomachine according to the intended use, the rotational axis of the turbomachine extends through the central point M perpendicular with respect to the image plane. Here, the rotational axis defines an axial direction. The radial direction extends perpendicularly with respect to the rotational axis. In the following, all directional specifications refer to an installation of the sealing element in a sealing system of a turbomachine according to the intended use.
What is further defined is a circumferential direction U that extends in a counterclockwise manner along the movement direction of the sealing element 1, in the case of installation in the sealing system according to the intended use and during operation of the sealing system. In principle, it is also possible for the rotational direction to be defined in the opposite direction.
In the embodiment according to
In the embodiment according to
In exemplary embodiments that are not shown here, also two or more than four rubbing elements 11 can be arranged at the sealing lip 10, wherein the arrangement can be rotationally symmetrical or asymmetrical.
In
Here, the rubbing element 11 is arranged inside a recess 100 of the sealing lip 10. The rubbing element 11 projects at least partially beyond the outer contour of the sealing lip 10, radially as well as on both sides axially.
In the cross-section perpendicular to the circumferential direction U, the sealing lip 10 has an isosceles, symmetrical, trapezoid-shaped contour, wherein the two side legs 10a, 10b taper off in the radial direction with growing distance from the central point M, that is, they form a convergent outer contour.
The bottom side of the sealing lip 10 is formed by the base 12 of the sealing element 1, wherein the base 12 with its rectangular cross-section has a larger extension in the axial direction than the sealing lip 10. The top side 10c of the sealing lip 10 extends in parallel to the base 12.
The recess 100 is formed as a milling groove of the sealing lip 10. It removes a part of the sealing lip material, but does not extend all the way up to the base 12 of the sealing element 1. All of the following exemplary embodiments also have the same structure of the sealing lip and the base, and the recesses 100 are also formed just like in this exemplary embodiment. However, in principle also other geometrical arrangements are possible.
The rubbing element 11 has multiple layers 110 made of rubbing material, wherein the rubbing material has a basic material G that is provided with abrasion particles P.
The first layer of the rubbing element 11, which is connected to the sealing lip 10, can form a separation layer 111. The separation layer 111 can decouple the rubbing element 11 from the sealing lip 10.
This separation layer 111 is followed by multiple layers 110, which become smaller in their axial extension with increasing radial distance from the central point M. What is created in this manner is a trapezoid outer contour of the rubbing element 11 that tapers off at least in certain sections.
Here, the layers 110, 111 of the rubbing element 11 axially project beyond the outer contour of the sealing lip 10 on both sides. In the radial direction, the rubbing element 11 has such a number of layers 110 of a corresponding thickness that at least one layer projects partially beyond the outer contour of the sealing lip 10 in the radial direction.
In some exemplary embodiments, the first layer of the rubbing element 11 can be formed identically to the further layers 110 of the rubbing element 11.
The layers 110, 111 of the rubbing element 11 are firmly bonded to each other and to the sealing lip 10 by means of laser deposition welding of the rubbing material. Unless otherwise specified, this also applies to all other exemplary embodiments with a layered structure of the rubbing element 11.
Since the surface of the rubbing element 11 has not been subjected to any further processing following the arrangement at the sealing lip 10 inside the recess 100, it has a roughness which in particular results from the layered structure and the abrasion particles P. None of the irregularities at the surface of the rubbing element 11, which result from the arrangement of the rubbing element 11 at the sealing lip 10, are subsequently corrected.
The abrasion particles P are sharp-edged particles that have an increased hardness as compared to the basic material G. Abrasion particles P can comprise cBN particles and/or TiC particles, for example.
Here and also in the following, the abrasion particles P are shown only in a symbolic manner and can take diverse regular as well as irregular shapes, in particular arbitrary geometrical shapes. It can also be assumed that in the following exemplary embodiments the rubbing element 11 has never undergone any post-processing, in particular of its surface, after it has been arrangement at the sealing lip 10.
Here, the basic material can consist of the same material as the sealing lip 10. The basic material G may contain a nickel-based alloy, such as for example Inco718, Inco718+, Udimet, Waspaloy and/or RR1000, or can consist completely of these alloys.
The composition of the rubbing material from a basic material that is intermixed with abrasion particles P may result in an increased abrasion effect of the rubbing element 11, especially due to the abrasion particles P. The rough areas on the surface of the rubbing element 11, which are created during the arrangement of the rubbing element 11 at the sealing lip 10, can also lead to an increased abrasion effect.
Due to the fact that the rubbing element 11 projects at least partially beyond the outer contour of the sealing lip 10, a run-in coating (which is not shown here) can be at least partially broached by the rubbing element 11 if the sealing element is installed in a sealing system according to the intended use, so that the sealing lip 10 itself hardly comes into contact or even does not come into contact at all with the run-in coating.
The rubbing element 11 projects beyond the outer contour of the sealing lip 10 in the axial as well as in the radial direction.
A difference to the embodiment variant according to
Another difference is that the layers 110 of the rubbing element 11 have a varying extension along the circumferential direction U also in the axial direction. Thus, the axial extension of the layers 110 decreases within each layer 110 along the circumferential direction U.
Also, the axial extension of the different layers 110 decreases from layer to layer in a manner analogous to the previous embodiment variant of
In
In this embodiment variant, the finished rubbing element 11 is formed in a layered manner inside the recess 100 of the sealing lip 10. The sealing lip 10 is connected to a base 12 of the sealing element 1.
What is shown in
The layers of the rubbing element 11 are formed by layer-wise laser deposition welding of the rubbing material inside the recess 100. Here, the rubbing material comprises a basic material that is intermixed with abrasion particles P.
In a further embodiment that is not shown here, the rubbing element 11, which is formed layer-by-layer from the rubbing material, can also be formed inside a recess 100 that extends all the way up to the base 12 of the sealing element 1. Thus, the rubbing element 11 can also be connected directly to the base 12, since no material of the sealing lip 10 remains in the area of the recess 100.
In
In
In
In
In
A recess 6 is arranged at the base area of the groove 5, which can be configured as a bore, for example. In this way, a propagation of cracks can be prevented or minimized, among other things.
In the shown embodiment, the groove 5 is arranged in parallel to the rotational axis of the seal. In alternative embodiments, the orientation of the grooves 5 can also be configured so as to be tilted with respect to the rotational axis.
With a view to simplicity, only a single groove 5 is shown here, wherein in principle a plurality of such grooves 5 can be used. Here, the grooves 5 can be distributed along the circumference in a regular or also in an irregular manner.
It should be noted that the features of the individual described exemplary embodiments of the invention can be combined with each other.
1 sealing element
5 groove, micro-slit
6 recess at the groove
10 sealing lip
10
a side leg of the sealing lip
10
b further side leg of the sealing lip
10
c top side of the sealing lip
100 recess inside the sealing lip
11 rubbing element
110 layers of the rubbing element
111 separation layer
12 base
U circumferential direction
G basic material
P abrasion particles
M central point of the sealing lip
Number | Date | Country | Kind |
---|---|---|---|
10 2015 217 670.3 | Sep 2015 | DE | national |