Brush seal

Details Brush seal Brush seal

2002-09-27

2004-05-11

Pickard, Alison K. (Department: 3676)

Seal for a joint or juncture

Seal between relatively movable parts

Brush seal

C277S415000, C277S547000

Reexamination Certificate

active

06733014

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a strip-like brush seal having a plurality of thin plates each of which is processed to have thin, cantilever beams at its one end and to a brush seal device, for sealing between a rotational shaft and a mating component movable relatively, for example in an aircraft and a gas turbine.
More particularly, the present invention relates to a technical field of a brush seal having thin beams that are protected from having scratches or damages.
2. Description of the Related Art
As shown in
FIG. 8
, there exists a brush seal device
100
as a prior art of the present invention.
FIG. 8
is a sectional view of a brush seal device
100
mounted between a rotational shaft
120
and a casing
110
through which the rotational shaft
120
passes. The casing
110
is a component of a steam turbine or gas turbine. The brush seal device
100
seals fluid by separating the casing
110
and the rotational shaft
120
.
In
FIG. 8
, the brush seal device
100
is formed in a ring shape and attached to a channel section
112
of the casing
110
. Main components of the brush seal device
100
are a brush seal
109
, a back plate
102
and a retaining plate
103
. In the brush seal
109
, a number of bristles
101
are formed into a bundle, which is in turn arranged circumferentially in the form of a wall. The bristles
101
are welded together at their outer ends to form an attachment section
104
. The free end face
105
as the other end of the brush seal
109
faces the rotational shaft
120
.
The diameter of each bristle
101
used in general is 0.02 to 0.5 mm. However, its sealing ability is poor because the bristle
101
is linear. In order to overcome such a drawback the thickness of the bundle of bristles
101
must be increased and thus tens of thousands or hundreds of thousands of bristles are necessarily used.
For such a brush seal
109
as described, countless number of these bristles
101
must be cut to has uniform length and then aligned circumferentially. it is therefore difficult to align them precisely. Further, it is also difficult to assemble with uniform accuracy in mass production. This causes defects.
An annular back plate
102
is disposed on one side face of the brush seal
109
with its side face
108
contacting the one side face of the brush seal
109
and bears the bristles
101
against the action of the sealed fluid pressure. A retaining plate
103
formed as a ring plate is disposed integrally on the other side face of the brush seal
109
to sandwich, in cooperation with the back plate
102
, the brush seal
109
on its attachment section
104
side. The retaining ring
103
has a small thickness in its radial direction so that the brush seal
109
is exposed to allow to deform itself, corresponding to the contact of the rotational shaft
120
therewith.
The back plate
102
, the attachment section
104
of the brush seal
109
and the retaining plate
103
are welded, with the attachment section
104
being located between the others, to form a connecting section
106
. The welded components are thermally deformed due to different materials among them and then some rework will be required, resulting in the increase of processing cost.
FIG. 9
is a partial front view, showing a state that the brush seal
109
fits normally without oscillation of the rotational shaft
120
, as shown by an actual line in FIG.
8
. The bristles
101
fit and extend straight, while incline in the rotating direction with respect to the radial direction of the rotational shaft
120
. Accordingly, after completion as a brush seal
109
, the fitting surface of the free end
105
is precisely finished so as to fit the rotational shaft
120
normally, as shown
FIG. 11
, which is a perspective view of the brush seal
109
, seen from the inner circumferential side thereof.
It is also difficult to process the free end
105
because the number of bristles in the form of a bundle is extremely large, such as several ten thousands and they are apt to deform. Furthermore, when the brush seal
109
having a finished free end
105
is, for example mounted, each bristle is deformed easily if it contacts or strikes any other parts. Such deformation will adversely affect on the sealing ability.
When the rotational shaft
120
contacts the free end
105
of the brush seal
109
as shown in
FIG. 10
, the brush seal
109
is pressed against the rotational shaft
120
, while its tilt angle is increased. During this state, the contact of the brush seal
109
with the rotational shaft
120
will be facilitated if there is some defective deformation at the free end
105
of each bristle
101
, resulting in its rapid wear.
In this state, as shown in
FIG. 8
, if the pressure of the sealed fluid is a high pressure P
1
, the differential pressure (P
1
-P
2
) between P
1
and a low pressure P
2
is increased and the sealing ability is worsened due to the deformation and wear on the free end
105
.
In the brush seal
2
constituted as described, each bristle
101
is a thin wire and its free end
105
is therefore apt to deform. During fabrication of the brush seal
2
, the free end
105
of the bristle may be deformed. Further, if it were not deformed during fabrication then the free end
105
might be bent when the brush seal
2
is installed on the casing
130
.
Also, it is difficult to finish exactly the end face of the free end
105
of the brush seal
2
so as to fit the rotational shaft
120
, resulting in the increase of processing cost.
Additionally, it is also difficult to weld the attachment section while the inner diameter formed by the end face of the free end
105
is made uniform. Because several ten thousands of bristles
101
are required to constitute a brush seal.
The present invention has been made in consideration of the problems as mentioned above, and technical problems of the invention are to allow to fabricate a brush seal unit without damages on the brush section of the brush seal and also allow to pile the brush seal units without damages and bent thereon.
Further technical problems of the present invention are to allow to provide a thin elastic wire capable of elastically deforming, corresponding to the contact of the brush seal with the rotational shaft and also allow to assemble the brush seal unit without damages on the brush section, even if thin wires are employed. Further yet technical problems are to improve the yield of material for fabricating the brush seals and to increase processing accuracy thereof.
Still other technical problems are to provide a brush seal with good ability of the brush seal to follow in response to the relative displacement between the brush seal and the outer circumference of the rotational shaft for improving the sealing ability and to improve the sealing ability of the contact or proximity between the brush seal and the rotational shaft.
SUMMARY OF THE INVENTION
The present invention has been made to solve the problems as mentioned above, and technical means for solving the problems are constituted as below.
A brush seal of first preferred embodiment according to the present invention is a brush seal mounted on one of two components that are relatively rotated, for sealing the clearance given between the two components, comprising: a plurality of the brush seal units, each having a strip-like brush section on the side facing the other component and having a base plate section on the side opposing the brush section side, the brush section being formed with thin beams each of which is between two slits, and the base plate section being fixed to the one component; the brush seal unit having, at the free end of the brush section, an ablative plate section integrally formed therewith and having a thin groove at the boundary between the brush section and the ablative plate section; wherein the ablative plate section is broken off at the groove before mounting the brush seal to be placed between the two components.
In the brush seal of the present invention, an ablative

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