Patent Application
20220034365
This application claims priority to German patent application no. 10 2020 209 677.5 filed on Jul. 31, 2020, the contents of which are fully incorporated herein by reference.
The present disclosure relates to a bearing assembly configured for improved sealing.
In bearing assemblies, for example, in large bearings, seals are used in order to seal the bearing inwardly and outwardly. In this way, for example, a leakage of lubricant can be prevented. In order to achieve a good seal tightness, a slip surface of the seal, i.e., a surface of the inner or outer ring on which the seal or a seal lip of the seal slips, is processed to make it as smooth as possible, for example, by grinding.
With large bearing diameters, weight-optimized housings are often used that lead to an elasticity of the entire system. This elasticity can lead to deformations of the entire system and thus to deformations of the seal, which deformations result in a serpentine contact path between the seal and the slip surface. Deformations of the seal in the contact region of the seal to the slip surface can thus arise that are locally larger than the bearing experiences on average. These deformations can be relatively long due to the large seal diameter and reduce the sealing capacity of the seal.
It is therefore an aspect of the present disclosure to provide a bearing assembly that compensates for reductions of seal capacity caused by deformations.
The disclosed bearing assembly includes at least one inner ring and at least one outer ring, between which at least one circumferential seal is disposed that slips on a circumferential slip surface of the inner ring or the outer ring. The bearing assembly can in particular be a large bearing assembly having an outer diameter of more than 2 m, in particular more than 4 m. The bearing assembly can be configured as a rolling-element bearing, for example, as a ball bearing or roller bearing, but also as a plain bearing.
As explained above, the sealing ability can be reduced by the deformation of the seal. In order to compensate for this reduced sealing ability, according to the bearing assembly proposed here it is provided to actively pump, inwardly or outwardly, a medium to be sealed against that could move through the seal due to the reduced sealing capacity. For this purpose, in the bearing assembly proposed here guide channels, in particular having constant, controlled orientation, are formed on the slip surface of the bearing ring. Alternatively in the bearing assembly proposed here, guide channels, in particular having constant, controlled orientation, are formed on the circumferential seal, preferably on a circumferential seal lip of the bearing assembly.
In contrast to known slip surfaces, which are formed as smooth as possible in order to minimize the wear of the slipping seal lip, here controlled guide channels are introduced into the slip surface. Due to these guide channels, it can be achieved that the medium to be sealed against is pumped inward or outward, depending on the desired seal effect in the bearing assembly. Here the guide channels have a magnitude that exceeds the local deformations of the seal, or of a seal lip of the seal, and in operation thus generates a pumping effect relative to the seal lip.
The medium to be sealed against can be a lubricant that is pumped through the guide channels into the bearing interior. Alternatively, for example, water, but also superfluous lubricant, can be pumped out from the bearing interior through the guide channels. The direction of the pumping effect can be changed by a changing of the rotational direction of the bearing assembly.
The guide channels can be configured as a plurality of recesses in the slip surface. Alternatively the guide channels can be defined by spaces between ribs that are formed on the slip surface. Depending on the requirement, the guide channels and their pitch can be configured with different widths or slopes, wherein preferably the width of the guide channels is constant over the circumference of the slip surface. The guide channels can be configured as a plurality of recesses in the circumferential seal. Alternatively a seal lip can have a constant pitch circumferentially, and thus, in the manner of a thread of a screw, a circumferential screw-like recess between the circumferential passages of the seal lip. Thus the guide channels are formed having constant pitch between the circumferential seal lips. Alternatively a plurality of seal lips can also be formed circumferentially in the manner of a multiply threaded screw, and guide channels form between them.
The guide channels are preferably distributed uniformly circumferentially. Due to the uniform distribution, the desired constant pitch can be ensured over the entire slip surface of the seal.
According to a further embodiment, the guide channels have a separation defining the pitch of greater than or equal to 0.5 mm, in particular greater than or equal to 1 mm, and preferably greater than or equal to 4 mm per rotation. Here the separation of a guide channel defines the offset of the guide channel in the circumferential direction.
As already explained above, in operation due to a large deformation of the entire structure, for example, of a turbine structure in use in a wind turbine, locally different angular misalignments of the seal lips can result. In these cases the seal effect between the seal and the slip surface is reduced locally in the short term. This can be compensated for by the particularly high separation of the guide channels, as is provided here.
The angular misalignments of the seal lip lead to an elastic deformation of the seal lip, which in turn leads to a wave shape of the seal lip on the slip surface. The division of the guide channels, which division produces the pitch, is chosen such that it is larger than the largest usually occurring pitches of the wave shape of the seal lip. It can thus be ensured that the pitch of the wave shape of the seal lip and the pitch of the guide channels do not match, and thus the seal lip does not extend in a guide channel. The desired pumping effect is thus ensured over the entire seal diameter, since the guide channels are not blocked by the seal lip.
A distance between the guide channels can in particular be smaller than the division. This has the advantage that a particularly finely structured surface is thereby achieved. It can thereby be ensured that a plurality of guide channels producing the pumping effect are always provided below the seal lip on the slip surface. A distance between the guide channels is preferably less than or equal to 0.1 mm.
According to a further embodiment, the slip surface has a surface roughness Ra that is less than or equal to 0.4 μm, in particular less than or equal to 0.2 μm, preferably less than or equal to 0.1 μm. Due to this surface roughness, the guide channels form a very smooth slip surface for the seal, which ensures the desired low seal wear. In comparison to conventional smooth slip surfaces, the friction of the seal is thereby not substantially increased, and thus the wear is not increased.
The slip surface can be a radial surface, a planar axial surface, or an oblique surface. Depending on the seal used, a corresponding slip surface can thus be equipped with guide channels.
According to a further embodiment, two circumferential seals are disposed between the inner ring and the outer ring, which seals each slip on a circumferential slip surface. For example, a corresponding seal having a corresponding slip surface can be provided on both axial sides of the bearing assembly. The two slip surfaces can preferably include opposing obliquely oriented guide channels such that, depending on the rotational direction of the bearing assembly, there is an inward or outward pumping effect.
Further advantages and advantageous embodiments are specified in the description, the drawings, and the claims. Here in particular the combinations of features specified in the description and in the drawings are purely exemplary, so that the features can also be present individually or combined in other ways.
In the following the invention is described in more detail using the exemplary embodiments depicted in the drawings. Here the exemplary embodiments and the combinations shown in the exemplary embodiments are purely exemplary and are not intended to define the scope of the invention. This scope is defined solely by the pending claims.
In the following, identical or functionally equivalent elements are designated by the same reference numbers.
In order to seal the bearing assembly 1, a seal 12 is provided that is, for example, attached to a housing 8. The seal 12 includes a seal lip 14 that slips on a slip surface 10 of the inner ring 2. Alternatively the seal 12 can also be attached to the inner ring 4, and in this case the seal lip 14 slips on a slip surface that is provided on the outer ring 2.
In the example shown in
The rotating part of the bearing assembly 1 can either be the part that includes the slip surface 10 or the part that holds the seal 12. The seal slip surface 10 can thus be disposed on a rotating outer ring 2 or a rotating inner ring 4 in the bearing assembly 1.
As is shown in
In comparison to previous slip surfaces that usually do not have surface textures, a slip surface 10 is provided here that makes possible guide channels 18 having a high pitch angle for the targeted pumping of media to be sealed against toward the bearing intermediate space or out of the bearing 1. Due to the guide channels 18, a better control of the medium to be sealed against can thus be achieved.
γ=arctan(P/D).
The pitch of the ribs 16 is preferably larger than the distance A between the guide channels 18.
The slope angle γ of the guide channels 18 is chosen such that the slope of the guide channels 18 is larger than the largest normally occurring slopes S of the wave shape 20 of the seal lip 14. It can thus be ensured that the slope S and the slope of the guide channels 18 do not match, and thus the seal lip 14 does not extend in a guide channel 18.
Despite the curved seal track 20, due to the guide channels 18 and the ribs 16, a pumping effect is always ensured between the slip surface 10 and the seal 12 over the circumference of the slip surface 10.
As is shown in
Due to the opposing arrangement of the ribs 16 or of the guide channels 18, an inward pumping effect, for example, into the bearing intermediate space 22, is achieved in order to seal the bearing interior against the loss of lubricant. In this way lubricant that is pressed outward by a rotation of the bearing assembly 1 can be pumped back into the bearing intermediate space 22 by the guide channels 18. Alternatively another medium, for example, water, but also superfluous lubricant, can be pumped out of the bearing intermediate space 22 by the guide channels 18. The direction of the pumping effect can be changed by a changing of the rotational direction of the bearing assembly 1.
In summary, due to the guide channels provided with a controlled, particularly large separation or pitch, an improved seal effect of the bearing assembly is achieved by the bearing assembly proposed here.
Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved bearing assemblies.
Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.
All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020209677.5 | Jul 2020 | DE | national |
