Brush seal

This application is a continuation application of co-pending U.S. patent application Ser. No. 12/898,952, filed 6 Oct. 2010, which is hereby incorporated herein.

Embodiments of the invention relate generally to brush seals and, more particularly, to segmented brush seals having a plurality of brush bristles angled with respect to an end of a backplate. Such an arrangement improves pressure balance and backplate support for the brush bristles, thereby preventing or reducing damage to brush bristles adjacent ends of the brush seal segments. Such an arrangement also reduces leakage through segment gaps to improve performance of the brush seal.

Known segmented brush seals may include segments having radially-oriented or angled brush bristles. The backplates of such segments typically have ends parallel to the brush bristles. Gaps will generally exist where segment ends meet to avoid arch-binding the segments in operation, resulting in increased brush seal radial clearance. As a consequence, there will be direct leakage paths through the gaps between brush seal segments, resulting in more leakage and a decrease in seal efficiency. In addition, brush bristles adjacent a segment end may fall into the gap and get damaged from lack of support and less pressure balancing and/or from rotor excursion, which both increases leakage and causes instability of nearby brush bristles, further decreasing the efficiency of the brush seal and inducing extensive bristle damage.

A brush seal and brush seal segment for use in a rotary device are provided.

In one embodiment, the invention provides a brush seal comprising: a plurality of brush seal segments, each segment including: an arcuate fence; an arcuate backplate substantially circumferentially coextensive with the arcuate fence, the arcuate backplate including a first end and a second end; and a plurality of brush seal bristles between the arcuate backplate and the arcuate fence, the plurality of brush seal bristles being angled with respect to a radial axis of the arcuate backplate and at least one of the first end and the second end of the arcuate backplate; and a static member to which at least one of the plurality of brush seal segments is affixed.

In another embodiment, the invention provides a brush seal segment comprising: an arcuate fence; an arcuate backplate substantially circumferentially coextensive with the arcuate fence, the arcuate backplate including a first end and a second end; and a plurality of brush seal bristles between the arcuate backplate and the arcuate fence, the plurality of brush seal bristles being angled with respect to a radial axis of the arcuate backplate and at least one of the first end and the second end of the arcuate backplate.

These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:

FIG. 1 shows a cross-sectional view of a rotary device having a brush seal and a rotor.

FIG. 2 shows portions of a brush seal segment according to an embodiment of the invention.

FIG. 3 shows a brush seal segment according to an embodiment of the invention.

FIG. 4 shows a portion of a brush seal according to an embodiment of the invention.

FIG. 5 shows a portion of a brush seal according to another embodiment of the invention.

FIG. 6 shows a portion of a brush seal according to yet another embodiment of the invention.

FIG. 7 shows a brush seal segment according to still another embodiment of the invention.

It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements among the drawings.

Turning now to the drawings, FIG. 1 shows a cross-sectional view of a rotary device 100 (e.g., gas turbine, steam turbine, generator, etc.) comprising a rotor 10 surrounded by a substantially circular static member 20 and a brush seal 90 therebetween. Brush seal 90 includes a plurality of segments 30 A, 30 B, 30 C, 30 D, 30 E, 30 F, one or more of which may be affixed to static member 20 . Such a brush seal may include any number of segments, typically between two and 12 segments. For the sake of brevity, the segments will be described further with respect only to segment 30 A.

Each segment 30 A includes an arcuate fence 40 A, an arcuate backplate (shown in subsequent figures and described further below), and a plurality of brush bristles 70 A. The plurality of brush bristles 70 A are disposed between fence 40 A and the backplate, and extend beyond an inner arcuate edge 46 A of fence 40 A, such that brush bristles 70 A may seal against rotor 10 as it rotates along path A.

As can be seen in FIG. 1 , brush bristles 70 A are angled at an angle α relative to a radial axis R of rotor 10 , segment 30 A, and static member 20 . Similarly, a first end 42 A and second end 44 A of fence 40 A are angled at an angle β and an angle γ, respectively, with respect to radial axis R. Although not essential, angles β and γ are typically the same, but they can be different from the bristles angle α. Such angles generally range, for example, from about 1° to about 60° with respect to radial axis R. As one skilled in the art will recognize, of course, in order for adjacent segments of brush seal 90 to properly align and provide a functional seal, a first end (e.g., 42 A) of a first fence (e.g., 40 A) must have an angle substantially the same as an angle of a second end (e.g., 44 F) of an adjacent second fence (e.g., 40 F).

FIG. 2 shows a fence 40 A, brush bristles 70 A, and arcuate backplate 50 A according to one embodiment of the invention. Arcuate backplate 50 A is shown circumferentially coextensive with fence 40 A. Brush bristles 70 A, first end 42 A, and second end 44 A are angled, α, β, and γ, respectively, relative to radial axes R 1 and R 2 . A first end 72 A and second end 74 A of bristles 70 A are angled substantially at the same angle α. As shown in FIG. 2 , angles β and γ are substantially the same. Backplate 50 A includes a first end 52 A and second end 54 A, each of which is substantially parallel to a radial axis R 1 , R 2 , respectively.

FIG. 3 shows backplate 50 A in place behind fence 40 A and brush bristles 70 A to form segment 30 A. As can be seen in FIG. 2 , a portion 51 A of backplate 50 A extends beyond second end 74 A of the bristle pack. Portion 51 A serves to support a portion of the brush bristles of an adjacent segment. Such an arrangement is shown in FIG. 4 , where an extending portion 71 B of brush bristles 70 B is disposed in front of portion 51 A of backplate 50 A when segments 30 A and 30 B are in place. This stepped gap design is made possible by the angled ends 72 A, 74 A of bristles 70 A combined with substantially radial ends 52 A, 54 A of backplate 50 A.

Other embodiments incorporating a stepped gap design are possible, of course. For example, FIG. 5 shows an embodiment of the invention wherein portion 151 A of backplate 150 A extends beyond first end 142 A of arcuate fence 140 A, rather than beyond second end 144 A, as would be the case in the embodiment shown in FIGS. 2-4 .

In another embodiment of the invention, such as that shown in FIG. 6 , first end 252 A, second end 254 A, or both, of backplate 250 A may be angled δ relative to radial axes R 1 , R 2 , respectively. Typically, angle δ would be to a side of a radial axis opposite that of angle α. That is, angle α will typically be “positive” (as defined in the direction of rotor rotation) and angle δ “negative,” (as against the rotor rotational direction), such that the “negative” angle δ increases portion 251 A of backplate 250 A extending beyond first end 272 A of bristles 270 A. As used herein, “positive” and “negative” are meant merely to illustrate opposite sides of a radial axis rather than any value of an angle relative to such an axis. Angle δ may have a value similar to that of angle α, i.e., between about 1° and about 60°, while β and γ may be the same as either bristle angle α or backplate end angle δ. For manufacturing reasons, the fence may have the same angle as the bristles and be aligned with the bristle pack along the segment ends.

FIG. 7 shows a brush seal segment 330 A according to another embodiment of the invention, wherein first end 342 A and second end 344 A of fence 340 A are substantially parallel to radial axes R 1 and R 2 , respectively, as are the ends of the backplate (not shown). That is, only brush bristles 370 A are angled α with respect to radial axes R 1 and R 2 . Such an arrangement forms a pair of voids 362 A, 364 A between fence 340 A and the backplate, into which brush bristles from an adjacent segment may be inserted during assembly of the brush seal.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any related or incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.