Seal for a joint or juncture – Seal between relatively movable parts – Brush seal
Reexamination Certificate
1999-12-03
2001-12-11
Browne, Lynne H. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Brush seal
Reexamination Certificate
active
06328311
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the leaktightness between two chambers or volumes that are subjected to different pressures and located around an axis or a revolving shaft. The invention particularly relates to aeronautical turbine engines that very often use the type of leaktight seal called a brush seal.
DISCUSSION OF THE BACKGROUND
Brush seals are bundles of wires, fibers or strands that can be metal, organic or synthetic. The material is chosen according to the environmental and operational conditions of the brush seal, i.e. according to the type of fluids to be kept leaktight, the temperatures and pressures present on either side of the seal.
Referring to
FIG. 1
, a joint of this type is used to separate two volumes or two chambers A and B that surround a revolving shaft
1
. Preferably, the bundle of wires
2
is positioned radially relative to revolving shaft
1
and the end
2
E of the bundle of wires touches the outer surface of revolving shaft
1
. The bundle of wires
2
is fitted into a fixed support
3
that constitutes the seal support. If we consider the direction of air that flows through the seal and that is indicated by arrow F, an upstream ring
5
is preferably used that is located upstream of bundle of wires
2
and that is positioned using a fastening ring
7
, said fastening ring being fastened in seal support
3
. A downstream ring
6
is also used, said ring being fastened downstream of bundle of wires
2
and positioned to bear against a rib
4
of seal support
3
. It should be noted that the inner diameter of downstream ring
6
is smaller than that of upstream ring
5
. In other words, the bundle of wires
2
is born over a greater distance by the downstream ring than by upstream ring
5
. End
2
E of bundle
2
has a certain degree of freedom, particularly on the upstream end i.e. of the upstream ring
5
. The seal thus separates two zones in which different pressures may be present.
Referring to
FIG. 2
, French patent application 2 607 893 discloses a brush seal that comprises several bundles, and more particularly three bundles in the example shown. The three bundles of wires
12
are fastened perpendicularly to revolving shaft
1
in relation to which they are used to separate several zones, particularly upstream zone A and downstream zone B that are positioned on either side of the assembly of three bundles of wires
12
. The bundles of wires
12
are held by upstream ring
15
and downstream ring
16
and are positioned relative to a seal support
13
using a rib
14
of said seal support.
The technical detail of all these types of brush seals are well known. On the other hand, it is not always easy to produce high quality brush seals.
Brush seals can also be positioned axially, for example in semi-static applications or to equip a slaved axial seal. In this event, it is impossible to implement the standard techniques used in the design of metal radial seals.
SUMMARY OF THE INVENTION
The aim of this invention is to propose a design of axial brush seals with a double leaktight wall. This design can also be applied to radial seals even though they may be more complicated to assemble.
In order to achieve this aim, the invention mainly relates to an axial or radial dual-contact brush seal to ensure leaktightness between two chambers subjected to different pressures and positioned around a shaft that is either revolving or fixed, comprising the following:
two flexible leaktight bundles that are parallel to each other and each end of which is in contact with the surface of the revolving or fixed shaft; and
a support body in which the two flexible leaktight bundles are fastened.
According to a main characteristic of the invention the two flexible leaktight bundles are constituted by a single, flexible, U-shaped strip the central section of which is fastened in the support body.
In the preferred embodiment the support body comprises two crowns: an inner crown and an outer crown, both of which are U-shaped and overlap each other.
Preferably, the arms of the two U-shaped crowns are not the same length such that the end of each leaktight bundle is only in contact with a single crown.
Preferably, in the event of a radial application, polarizing means are used to ensure the two crowns are assembled in the correct direction.
REFERENCES:
patent: 885032 (1908-04-01), Ferranti
patent: 5066024 (1991-11-01), Reisinger et al.
patent: 5114159 (1992-05-01), Baird et al.
patent: 5794938 (1998-08-01), Hofner et al.
patent: 0 211 275 (1987-02-01), None
patent: 2 607 893 (1988-06-01), None
Plona Daniel Georges
Thore Monique Andrée
Browne Lynne H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Peavey E.
Societe Nationale d'Etude et de Construction de Moteurs d&a
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