Seal of non-hermetic design

Details Seal of non-hermetic design Seal of non-hermetic design

2001-04-03

2004-06-01

Knight, Anthony (Department: 3676)

Seal for a joint or juncture

Seal between relatively movable parts

Close proximity seal

C277S411000, C277S500000, C277S355000

Reexamination Certificate

active

06742782

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a seal of non-hermetic design for installation between two components which can move relative to each other, in particular between a rotor and a stator of a turbo-engine, having a multiplicity of flexurally elastic sealing elements which each have an end connected fixedly to a seal-bearing arrangement and a free, angled end with the point directed toward the surface of the one component.
BACKGROUND INFORMATION
A seal of this type is described, for example, in German Published Patent Application No. 196 18 475. The flexurally elastic sealing elements are designed as angled bristles, i.e., this seal is a special design of a brush seal. This design has the advantage that given sufficient elasticity of the bristles, i.e., sufficient bending length, particularly small seal dimensions can be realized in the direction of the angled bristle sections. In the case of a shaft seal having bristle ends angled radially toward the shaft axis, the overall radial height and therefore the diameter of the seal can be made to be extremely small. This criterion may, for example, be decisive if the brush seal is to be installed as a structural replacement for a labyrinth seal where sufficient axial, but little radial, constructional space is available. In the case of an end-face seal, the angled bristle ends are orientated axially, in which case the required bending length can be accommodated in the radial direction. The advantages with regard to a minimum space requirement in one direction, i.e., axially, are apparent. However, the manufacture of such “hook-type brush seals” is relatively complicated and expensive. This is primarily because a multiplicity of angled bristles, for example several hundred bristles, have to be orientated in a defined manner on a bearing arrangement and attached permanently, in which case a multiplicity of bristle layers above or next to one another is generally also required. In addition, the fine, angled, generally metallic bristles are very sensitive and can easily be permanently deformed or broken off.
German Published Patent Application No. 44 03 605 describes the use of flexurally elastic lamellae having a relatively large width transversely to the direction of movement of the component as sealing elements. The lamellae slide in the manner of an obliquely positioned spatula over the surface of the component or over a gas cushion produced dynamically. A shaft seal designed in accordance with this principle has a high leakage rate, since the axial gaps correspond in respect of size and number approximately to the lamellae. The arrangement of a plurality of lamella rings, which are optionally offset angularly, axially one behind another, can only provide a partial remedy. It would therefore also not be possible for this design to be more successful than the brush seal.
In view of the foregoing and the disadvantages thereof, it is an object of the present invention to provide a seal of non-hermetic design having a multiplicity of flexurally elastic, angled sealing elements, which seal is simpler and less expensive to produce and more robust in operation in relation to a conventional brush seal.
The above and other beneficial objects of the present invention are achieved by providing a seal as described herein. Instead of bristles, thin-walled, angled spring leaves are used which are arranged in at least two layers one above the other with alternate overlapping. This arrangement considerably reduces the number of sealing elements. With precise manufacturing of the sealing elements and of the seal-bearing arrangement, the integration of these parts results in the desired seal geometry. Misorientation of sealing elements, as in the case of “hook-type bristles”, is virtually eliminated. The outlay on refinishing work is considerably lower. It is also to be expected that the “spring-leaf” sealing elements, in handling, for example in installation and removal of the seal, and in operation, are substantially less sensitive with regard to plastic deformation and fracture than bristles and therefore also withstand higher differential pressures.


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patent: 5934687 (1999-08-01), Bagepalli et al.
patent: 44 03 605 (1995-11-01), None
patent: 196 18 475 (1997-11-01), None
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patent: 0 933 567 (1999-08-01), None

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