Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
1999-10-29
2001-11-13
Sandy, Robert J. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S581000, C277S589000
Reexamination Certificate
active
06315301
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seal device for effecting a gas seal in a rotating machine of a gas turbine and the like in which a high temperature gas flows.
2. Description of the Prior Art
FIG. 7
is a cross sectional view of a related portion of a prior art gas turbine. In
FIG. 7
, numeral
1
designates a turbine disc, which is fixed to a rotating shaft. Numeral
10
designates a moving blade, which is implanted in an outer circumferential portion of the turbine disc
1
and numeral
11
designates a stationary blade. A cooling air cavity
14
is formed between the turbine discs
1
,
1
of mutually adjacent stages and a labyrinth seal
15
is provided on an inner circumferential surface of the stationary blade
11
for effecting a gas seal between a gas path
12
and the cooling air cavity
14
. Numeral
13
designates a cooling air passage for leading therethrough a cooling fluid into the cooling air cavity
14
.
Numeral
2
designates a seal plate provided in the turbine discs
1
,
1
on an inner side of the labyrinth seal
15
. As shown in
FIG. 8
, the seal plate
2
is a thin metal ring, which is divided into plural pieces (two pieces in this example) in the circumferential direction. A divided part
2
c
has its upper and lower divided surfaces formed in stepped shapes, respectively, so as to be gas tight when they are mated with each other. The seal plate
2
is assembled into grooves
1
a
(see
FIG. 2
) provided in the mutually adjacent turbine discs
1
,
1
. While in operation, the seal plate
2
is pressed against outer circumferential wall surfaces
1
b
of the grooves
1
a
by the centrifugal force of the seal plate
2
itself due to a high speed rotation of the turbine discs
1
,
1
, so that the cooling fluids is prevented from leaking into the gas path
12
side by a differential pressure between the gas path
12
and the cooling air cavity
14
.
In the gas turbine using the mentioned prior art seal plate, the seal plate
2
is divided into plural pieces in the circumferential direction and so the fluid intrudes easily into the divided part
2
c
. Also, as the seal plate
2
is pressed against the outer circumferential wall surfaces
1
b
of the grooves
1
a
of the turbine discs
1
,
1
only by its own centrifugal force, the pressing force is small and self-induced vibration of the seal plate
2
is liable to occur when the fluid so intrudes. Thus, in the prior art seal structure as mentioned above, there is often caused abrasion or thinning of the seal plate
2
by the self-induced vibration, which results in the problem of deterioration of the sealing performance.
SUMMARY OF THE INVENTION
In view of the problem in the prior art, therefore, it is an object of the present invention to provide a rotating machine seal device in which a seal plate is fitted to a turbine disc securely by a large fitting force, thereby to reduce self-induced vibration of the seal plate and also to prevent abrasion or thinning of the seal plate caused by the self-induced vibration, as well as to prevent deterioration of the sealing performance associated therewith.
In order to achieve the object, the present invention provides as a first embodiment a rotating machine seal device having a seal plate inserted into a groove provided in a disc portion driven rotationally, the seal device being for sealing fluid between a fluid passage on an outer circumferential side of the groove and a fluid passage on an inner circumferential side of the groove. The seal plate is divided into plural pieces along a circumferential direction thereof to be inserted into the groove of the disc portion, and a spring plate is disposed on an inner circumferential side of the seal plate so that the seal plate is pressed against a seal surface of the groove by a spring force of the spring plate.
According to the mentioned embodiment, while the rotating machine is in operation, the seal plate receives not only its own centrifugal force but also the spring force and the centrifugal force of the spring plate to be pressed against the seal surfaces of the grooves by the combined force thereof, thus the seal of the fluid on the seal surfaces can be effected securely. Also, the combined force is strong enough for pressing the seal plate against the seal surfaces of the grooves of the disc portion such that even if the fluid intrudes into the divided part of the seal plate, self-induced vibration is reduced relative to such a self-induced vibration as in the prior art case, which results in the prevention of abrasion or thinning of the seal plate due to the self-induced vibration.
The present invention provides as a second embodiment a rotating machine seal device of the first embodiment, characterized in that the seal plate is made from a plurality of seal plates lapped one on another to be inserted into the groove, and the spring plate is disposed on an inner circumferential side of the plurality of seal plates.
According to the second embodiment, because the seal plate is made from the plurality of seal plates lapped one on another, the centrifugal force of the seal plate itself increases and the seal plate can be pressed against the seal surfaces of the grooves by a larger pressing force, which results in the further enhancement of the sealing performance. Also, by the effect of friction on the contact surfaces of the plurality of seal plates, the self-induced vibration can be reduced further.
As a third embodiment, the present invention provides a rotating machine seal device having a seal plate inserted into a groove provided in a disc portion driven rotationally, wherein the seal device is for sealing fluid between a fluid passage on an outer circumferential side of the groove and a fluid passage on an inner circumferential side of the groove. The seal plate is divided into plural pieces along a circumferential direction thereof and one piece of the seal plate in a divided part has a projection formed thereon, while the other piece thereof in the divided part has a groove formed therein so that the projection is inserted into the groove with a predetermined space remaining in the circumferential direction of the seal plate.
According to the third embodiment, the plural pieces of the divided seal plate are connected to each other in the circumferential direction with the projection and the groove of the respective seal plate pieces being mated with each other with the space therebetween, thereby the assembling work of the seal plate can be facilitated and the circumferential directional stress of the seal plate can be reduced.
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patent: 4251083 (1981-02-01), Montes
patent: 4537024 (1985-08-01), Grosjean
patent: 5221096 (1993-06-01), Heldreth et al.
patent: 5865600 (1999-02-01), Mori et al.
patent: 5997247 (1999-12-01), Arraitz et al.
patent: 58-96105 (1983-06-01), None
patent: 3-141804 (1991-06-01), None
patent: 09133005 (1997-05-01), None
patent: 09242505 (1997-09-01), None
patent: 10-2203 (1998-01-01), None
Akagi Koichi
Kubota Jun
Ono Masaki
Umemura Sunao
Mitsubishi Heavy Industries Ltd.
Sandy Robert J.
Schwing Karlena D.
Wenderoth , Lind & Ponack, L.L.P.
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