Brush seal device

Details Brush seal device Brush seal device

2002-06-14

2003-11-18

Knight, Anthony (Department: 3676)

Seal for a joint or juncture

Seal between relatively movable parts

Brush seal

Reexamination Certificate

active

06648334

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brush seal device for sealing a clearance between a rotary shaft and a mating component that are relatively movable. More particularly, the present invention relates to a brush seal device that is disposed between two components relatively movable in, for example a gas turbine and an airplane and seals the clearance in away that a brush seal is deformed to follow the change in the movement of one component even if the one component changes slightly its movement relative to the other component.
2. Description of the Related Art
As a related art to the present invention there exists a brush seal device
100
, as shown in FIG.
9
.
FIG. 9
is a sectional view of a brush seal device
100
mounted between a rotary shaft
120
and a casing
110
through which the rotary shaft
120
passes. The casing
110
is a fixed component of, for example, a steam turbine or a gas turbine. The brush seal device
100
attached to the casing
110
seals fluid to be sealed between the casing
110
and the rotary shaft
120
.
In
FIG. 9
, the brush seal device
100
is formed in the shape of a ring and its attachment section
104
on its outer circumference is attached to a channel portion
112
of the casing
110
. Main components of the brush seal device
100
are a brush seal
109
, a backing plate
102
, and a support plate
103
. In the brush seal
109
, bristles
101
are arranged around a circular circumference to form a wall having a certain width and with their outer ends being coupled to form an attachment section
104
. The free end
105
on the inner circumference side of the brush seal
109
faces the rotary shaft
120
. The diameter of a bristle
101
generally used is 0.20 mm or more.
An annular backing plate
102
is disposed on a side face of the brush seal
109
with its side face
108
being in contact with the brush seal
109
, supporting the bristles
101
against the action due to the pressure of the sealed fluid.
A support plate
103
formed as a ring plate is disposed on the other side face of the brush seal
109
to sandwich, in cooperation with the backing plate
102
, the brush seal
109
on its attachment section
104
side, thereby to couples them in a body. The inside diameter of the support plate
103
is made large so that the sealed fluid can effect on the side face of the brush seal
109
. The brush seal
109
is exposed at its free end
105
.
Outer circumference sides of the backing plate
102
, the attachment section
104
of the brush seal
109
, and the support plate
103
are welded to form a connecting section
106
.
FIG. 10
is a front view of the brush seal
109
. The brush seal
109
in
FIG. 10
is in a state that the brush seal
109
and the rotary shaft
120
are normally fitted without oscillation, such that the bristles
101
extend straight and oriented to incline relative to the radial direction of the rotary shaft
120
. In the normal state of the brush seal
109
, the rotary shaft
120
is in contact with or close to the free end
105
, as shown by the solid line in FIG.
9
.
Another related art is also shown in FIG.
11
. In the drawing, a connecting section
106
of a brush seal
109
is contained within an attachment section
131
of a brush holder
130
and is allowed to move in the radial direction. A plate spring
132
urges the connecting section
106
to bear in the radial direction of the rotary shaft
120
.
When the rotary shaft
120
eccentrically presses against the brush seal, it becomes complex to calculate two spring constant, one corresponding to the resilient deformation of bristles, and the other to the resilient deformation of the plate spring
132
, due to the involvement of the complexity in friction generated from its mounting structure. Since those two spring constants and other frictions are the elements for the design of the device, it is extremely difficult to achieve optimum design or improvement in consideration of the pressure generated by the displacement of the rotary shaft
120
. Thus, the ability of the bristles
101
to follow the displacement of the rotary shaft
120
is not fully performed and it results in quick abrasion of the free end
105
of bristles.
In addition, the ability of the bristles
101
having a larger diameter to follow is poor when the bristles contact the rotary shaft
120
. Moreover, as the thickness of a bundle of bristles becomes larger, the ability to follow becomes poorer. Accordingly, it is limited to make the thickness of the bundle of bristles large. Thus, the sealing ability is necessarily reduced.
In the brush seal device
100
configured as above, while the brush seal
109
is pressed against the rotary shaft
120
as shown in
FIG. 12
, when eccentricity or vibration causes the rotary shaft
120
to contact the brush seal
109
, its tilt angle is further increased.
In this condition, if the pressure of the sealed fluid is high pressure (P
1
), since the differential pressure (P
1
-P
2
) between the high pressure (P
1
) and the low pressure (P
2
) becomes large as shown in
FIG. 9
, the entire straight bristles of the brush seal
109
are pressed against the backing plate
102
and then it becomes difficult for them to deflect in response to the contact with the rotary shaft
120
, that is, the ability to follow in response to the rotary shaft
120
is worsened. Also, when the sealed fluid flows into spaces between bristles
101
, each bristle
101
is easily pushed apart and thus the tilted bristles
101
tend to displace at its side pushed apart such that tilt angle becomes smaller, thereby to form clearances among the bristles
101
. Then the bristles
101
, each of which was pushed apart and has a small tilt angle transit to the state that their length in the radial direction are longer. Accordingly, pressure exerted by the rotary shaft
120
is further increased to wear the bristles.
In routing such behaviors as describe, the clearance C that is given between the free end
105
of the bristles
101
on the side diametrically opposite to the side where the brush seal
101
is pressed against the rotary shaft
120
, as shown in
FIG. 12
, is extended as shown in
FIG. 13
, causing leakage of the sealed fluid out of the clearance C.
The present invention has been made in consideration of the problems as mentioned above and the technical problems to be solved are: to reduce the resilient force exerted on the brush seal caused by the pressure of the rotary shaft so that abrasion of the brush seal by the rotary shaft can be reduced; to improve the ability of the brush seal to follow in response to the change of the rotary shaft for increasing the sealing ability; and to achieve to obtain a brush seal in the shape of a rectangular strip so as to allow resilient deformation and increase the sealing ability.
SUMMARY OF THE INVENTION
The present invention has been made to solve the problems as described above, and technical means for solving them are constituted as below.
A brush seal device of a preferred embodiment according to the present invention is one which is mounted to one of two components rotatable each other with a clearance there between, and seals the clearance, comprising: a brush seal having an attachment section for fixing one end of a row of bristles arranged in the shape of a wall and having a free end facing the surface of the other component, wherein each of the bristles in the brush seal has a bending portion in the middle for facilitating resilient buckling deformation of the bristle.
In the brush seal device of a preferred embodiment according to the present invention, in the middle of a bristle of a brush seal is defined a bending portion for facilitating resilient deformation, and the flexible bending portion can be deformed resiliently when action force from a rotary shaft exerts on the free ends of the bristles, to follow the circumference of the rotary shaft, and the sealing ability will fully perform. The brash seal may be in the shape of shape of rectangular strips, as

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