Seal for a joint or juncture – Seal between relatively movable parts – Brush seal
Reexamination Certificate
2000-01-25
2001-12-18
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Brush seal
Reexamination Certificate
active
06331006
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to brush seals and more particularly to a resilient mounting for brush seals between a rotating component and a component fixed against rotation which facilitates installation of the seal.
Brush seals are commonly used to minimize leakage through a gap between a rotating component and a component fixed against rotation. For example, brush seals are commonly used in rotating machinery such as steam turbines and gas turbines used for power generation. Typically, in a steam turbine, the brush seals minimize leakage of steam and in a gas turbine, minimize leakage of compressed air or combustion gases.
Brush seals are normally formed in arcuate segments, generally conforming to the circumference of the components to be sealed. Each segment typically includes a pair of plates with a plurality of brush bristles disposed between the plates. The plates and ends of the brush bristles between the plates are typically welded to one another, forming a completed brush seal segment. Opposite ends of the bristles project from between the plates and form a seal with the other component, typically the rotating component. One of the plates may be formed with an axially extending hook or flange for mating in a corresponding groove typically on the component fixed against rotation. The brush seals are radially positioned by the close fit between the projecting hook on the brush seal segment and the mating groove of the fixed component, close radial positioning being required for satisfactory functioning of the seal. That close radial positioning, however, requires tight tolerances between the brush seal hook and the groove of the fixed component, resulting in costly parts and potential for installation difficulty. Consequently, there has developed a need for a brush seal installation which can minimize or eliminate the heretofore need for tight tolerances between the brush seal's projecting hook and the corresponding groove whereby the potential for installation problems can be minimized or eliminated.
BRIEF SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention, there is provided a brush seal segment having projecting bristles for forming a seal between a rotary component and a component fixed against rotation. The latter component typically carries the brush seal segment. For example, the brush seal segment in accordance with a preferred form of the present invention may be mounted in a spill strip ring having labyrinth teeth spaced axially from the brush seal segment for forming a combined labyrinth/brush seal with covers of the rotating buckets. To facilitate the installation of the brush seal segment in the spill strip ring or other components fixed against rotation, generous clearances may be provided between the radial height of the brush seal hook and the groove receiving the flange. Particularly, the brush seal segment may be formed of a pair of plates, i.e., a front plate and a back plate, with brush bristles disposed between the plates, the plates and ends of the bristles being welded along an arcuate face of the brush seal segment. The brush seal bristles, of course, extend from the opposite arcuate edge of the brush seal segment for sealing engagement with the other component.
A spring is disposed between the arcuate face of the brush seal segment and the base of the groove in which the segment resides. Preferably, the spring is a flat leaf spring. In order to preclude circumferential movement of the spring relative to the brush seal segment, the spring is fixed against circumferential movement to the segment. To accomplish this, and in accordance with a preferred form of the present invention, the spring has at least one and preferably a pair of tabs projecting toward the arcuate face of the brush seal segment. The segment has at least one and preferably a pair of radial recesses for receiving the tabs. In this manner, with the tab or tabs received in the recess or recesses, movement of the spring in a circumferential direction is precluded. It will be appreciated that if a single tab is employed to couple the spring and brush seal segment to one another, the tab and recessed arrangement must be spaced from the weld between the plates and the bristles. Otherwise, a break in the weld to accommodate a tab on the spring would locally remove the bristles secured to the segment by the weld. Consequently, in accordance with a preferred form of the present invention, the tab and recess combination lies on one side of the weld or if a pair of tabs and recesses are employed, the tabs and recesses straddle the weld whereby the bristles in the brush seal segment remain intact and secured to the segment. While arcuate sealing segments backed by springs and typically mounting labyrinth seal teeth have been previously employed, backing a brush seal with a spring to bias the seal toward the opposite component has not heretofore to our knowledge been accomplished.
In a preferred embodiment according to the present invention, there is provided a brush seal and spring combination for disposition between a first rotatable component and a second component fixed against rotation, comprising an arcuate brush seal segment for disposition between the first component and the second component and including a pair of arcuate plates, a plurality of brush bristles projecting therefrom having free ends for sealing with the first rotatable component and a weld along the outer face of the plates securing the plates and bristles to one another, and an elongated leaf spring for disposition between the brush seal segment and the second component for biasing the brush seal segment toward the rotating component.
In a further preferred embodiment according to the present invention, there is provided a brush seal and spring combination for disposition between a first rotatable component and a second component fixed against rotation, comprising an arcuate brush seal segment for disposition between the first component and the second component and including a pair of arcuate plates, a plurality of brush bristles projecting therefrom having free ends for sealing with the first rotatable component and a weld along the outer face of the plates securing the plates and bristles to one another, one of the plates having a recess along a radially outer face thereof, and an elongated leaf spring for disposition between the brush seal segment and the second component and having a radially inwardly directed tab for engaging in the recess, the recess and tab being spaced from the weld.
In a still further preferred embodiment according to the present invention, there is provided a brush seal assembly comprising a first rotatable component having an axis of rotation, a second component fixed against rotation about the axis and radially outwardly of the radial component, the fixed component having an axially opening groove, an arcuate brush seal between the rotatable component and the fixed component and including an axial projecting hook for reception in the groove, the brush seal having a support mounting a plurality of bristles projecting therefrom and having free ends in sealing relation with the rotary component, the support having an arcuate radial outer face, a spring between the fixed component and the outer face for biasing the brush seal for movement in a generally radially inward direction, the outer face having at least one recess and the spring having a projecting tab received in the recess.
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patent: 1895930 (193
Baily Frederick G.
Rentz Lawrence E.
Retzlaff Klaus M.
Turnquist Norman A.
Beres John L.
General Electric Company
Knight Anthony
Nixon & Vanderhye
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