Abstract:
A front plate and brush seal assembly for providing a seal between a high pressure area and a low pressure area. An embodiment of a front plate includes a front plate body. The front plate body includes an inner peripheral edge and an outer peripheral edge. A plurality of cuts or slots are provided in the front plate body and extend from the outer peripheral edge of the front plate body toward the inner peripheral edge of the front plate body, such that the plurality of cuts or slots do not extend to the inner peripheral edge, and the plurality of cuts or slots define a plurality of fingers in the front plate body. In an embodiment of a brush seal assembly, the assembly includes a retaining plate that is connected to a front plate.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to shaft seals, such as those used in connection with gas turbine engines. 
       BACKGROUND 
       [0002]    Brush seals have been employed as a means for sealing high pressure gas or fluid areas from low pressure gas or fluid areas. For example, brush seals may be used in connection with gas turbine engines. Brush seals commonly inhibit flow of gas or liquid along a shaft. Conventional brush seals typically include an annular retaining plate, an annular back plate, and a plurality of flexible bristles (or a bristle pack) that are secured between the retaining plate and back plate. When a brush seal is used to provide a seal with respect to a shaft, the tips of the bristles generally contact or run near the shaft to seal a system pressure from a discharge pressure. 
         [0003]    Some conventional brush seals provide a recessed back plate and a flexible front plate that is concentric with the bristle pack. The front plate may be provided on the high pressure side of the bristle pack. A plurality of fingers may be provided to sandwich the bristle pack between the front plate and a rigid back plate. An example of a brush seal with a flexible front plate is disclosed in U.S. Pat. No. 5,884,918 to Basu et al. 
       SUMMARY 
       [0004]    A front plate and brush seal assembly for providing a seal between a high pressure area and a low pressure area. An embodiment of a front plate includes a front plate body. The front plate body includes an inner peripheral edge and an outer peripheral edge. A plurality of cuts or slots are provided in the front plate body and extend from the outer peripheral edge of the front plate body toward the inner peripheral edge of the front plate body, such that the plurality of cuts or slots do not extend to the inner peripheral edge, and the plurality of cuts or slots define a plurality of fingers in the front plate body. In an embodiment of a brush seal assembly, the assembly includes a retaining plate that is connected to a front plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein: 
           [0006]      FIG. 1  is partial front view of an embodiment of a front plate in accordance with teachings of the invention; 
           [0007]      FIG. 2  is a partial front view of another embodiment of a front plate in accordance with teachings of the invention; 
           [0008]      FIG. 3A  is side cross sectional view of a front plate-retainer plate assembly according to an embodiment of the invention; 
           [0009]      FIG. 3B  is a front view of a portion of the assembly illustrated in  FIG. 3A ; 
           [0010]      FIGS. 4 ,  5 , and  6  are side cross sectional views of embodiments of front plate-retainer plate assemblies according to other embodiments of the invention; 
           [0011]      FIG. 7  generally illustrates a partial front view of a double-groove embodiment of the invention with a plurality of slots provided in the associated land region; and 
           [0012]      FIGS. 8 ,  9 , and  10  are partial front views of embodiments of front plate-retainer plate assemblies according to yet other embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Reference will now be made in detail to embodiments of the present invention, examples of which are described herein and illustrated in the accompanying drawings. While the invention will be described in conjunction with embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0014]      FIGS. 1 and 2  illustrate embodiments of front plates  10  shown in accordance with teachings of the present invention.  FIG. 1  generally depicts a portion of a front plate  10  (also referred to as a “front plate body”) including slots  12  (or sometimes also referred to as “cuts”)—in this instance radial slots—that define a plurality of fingers  14 .  FIG. 2  also generally illustrates a front plate  10  that includes slots  12 . However, the slots  12  included in the front plate  10  are angled and serve to define angled fingers  14  in the front plate  10 . 
         [0015]    In embodiments, for example as illustrated in  FIGS. 1 and 2 , slots  12  extend from an outer peripheral edge  40  of the front plate toward an inner peripheral edge  50 . However, it is noted that the slots  12  shown in the illustrated embodiments do not extend up to (or through) the inner diameter, i.e., that is the slots  12  do not extend all the way up the inner peripheral edge  50 . The slot-finger configurations may take on a variety of types and forms, including radial slots (see, e.g.,  FIG. 1 ) and angled slots (see, e.g.,  FIG. 2 ). Without limitation, in an embodiment the slots  12  are within the range of from about 3 mils to about 15 mils wide. However, the invention is not limited to a single configuration, and the numbers, sizes, and/or patterns of slots may vary. 
         [0016]    In embodiments, to help maintain a desired amount of axial flexibility, the outer diameter of the flexible front plate  10  should be permitted to move or translate to some degree in the radial direction. This may be contrary to certain retention objectives associated with some prior seal configurations, which often prevent the front plate from shifting radially—for example, where tack or spot welding is employed to secure the front plate to a retaining plate. With embodiments of the invention, the front plate  10  is restrained at a portion adjacent or near the inner diameter (or inner peripheral edge). However, not all welding and similar restraining techniques are desirable as some techniques can introduce undesirable axial stiffness into the movement of the flexible front plate  10  by restricting radial movement of the front plate  10 . With embodiments of the invention, features can be introduced that allow welding (e.g., spot welding) of the flexible front plate  10  to a retaining plate without unduly impacting axial stiffness. 
         [0017]    In embodiments of the invention, the flexible front plate  10  will be retained at or about a portion near the outer diameter. For embodiments of the invention, the front plate  10  will be restrained in the circumferential direction, but some radial movement (e.g., substantially symmetrical radial movement at the front plate outer diameter) may be permitted. This manner of restraint or retention can be accomplished by employing various techniques. 
         [0018]    For instance, in an embodiment, a feature or portion  16  of the front plate  10  may be “trapped,” or retained or restrained, in a corresponding or mating feature associated with a retainer, e.g., a retaining plate.  FIGS. 3A and 3B  generally illustrate an embodiment of an assembly  20  that includes a flexible front plate  10  and an associated retaining plate  30 . In the illustrated embodiment, flexible front plate  10  includes a portion  16  (e.g., a lip) that may be trapped or restrained (e.g., in a sliding interface or arrangement) by or within a portion of a formation  32  (e.g., a groove or recess) associated with the retaining plate  30 . In other embodiments, trapping or retention of a portion of the front plate  10 , i.e., at or about the outer diameter portion thereof, can also be provided by placing the flexible front plate  10  in a groove machined in the retaining plate  30 . With such configurations, the flexible front plate  10  can be captured or retained between a bristle pack and a retaining plate. 
         [0019]    In another embodiment, a welding-type technique, e.g., spot welding—can be employed at specific or select locations toward the end of the flexible front plate  10  closer in proximity to the outer diameter of the front plate  10 . For such embodiments, it is generally desirable to weld portions of the front plate  10  at only a few locations (e.g., locations  40  generally illustrated in  FIGS. 4 and 5 ) so as not to substantially or unduly increase the axial stiffness of the front plate  10 . 
         [0020]      FIGS. 5 and 6  generally illustrate another embodiment of the assembly  20 . In this embodiment, a plurality of grooves—which may comprise a double-groove—may be provided (e.g., machined) in a retaining plate  30 . Flexible front plate  10  may be welded (e.g., spot welded) at specific locations (such as generally illustrated as locations  50  in  FIG. 6 ) that correspond to portions of a land region  60  (see, e.g.,  FIG. 7 ) that are provided between the grooves in the retaining plate  30 . 
         [0021]    In embodiments of the assembly that employ a double-groove, a portion of a land region (or “beam”) can effectively be provided that can, itself, deflect in the radial direction. If desired, to further weaken the beam kerfs or slots can be provided in the land region. For example and without limitation, as generally illustrated in  FIG. 7 , a plurality of slots can be cut at select angles in the land regions. 
         [0022]      FIG. 8  generally illustrates an embodiment of the invention in which cuts or kerfs  12  are provided in a flexible front plate  10 . In the illustrated embodiment, the cuts or kerfs  12  are not straight, but are turned or angled before breaking continuing on to the outer diameter OD of the front plate  10 . This type of configuration can provide a cantilever-type beam in connection with a front plate  10 . In an embodiment one or more weld locations (e.g., spot weld locations)  80 , or other forms of connecting techniques, may be utilized to connect front plate  10  to retaining plate  30 . The one or more weld locations  80  may be provided in a cantilever beam section (generally designated as section  90  in  FIG. 8 ) of front plate  10 . Such a configuration can permit some flexibility of the front plate  10  in the radial direction when axial deflection of the front plate  10  occurs. 
         [0023]    A further non-limiting example of a connection configuration between a flexible front plate  10  and a retaining plate  30  is shown in  FIG. 9 . As generally illustrated, a separate or independent cantilever beam section  90  may be provided (e.g., cut) in the flexible front plate  10 . In such an embodiment, the cantilever beam section  90  is not part of the cuts or slots  12  between the defined fingers  14 . In an embodiment, and as generally shown in  FIG. 9 , one or more weld locations  80  may be provided to weld (or connect) the flexible front plate  10  to the retainer plate  30 . This can offer a measure of radial motion flexibility with respect to the front plate  10 . 
         [0024]    With further reference to  FIGS. 8 and 9 , a distance D is generally illustrated. The distance D generally represents a distance from the innermost radial portion of a cut or slot  12  and the inner diameter ID of the flexible front plate  10 . By way of example, and without limitation as to the embodiments illustrated in  FIGS. 8 and 9 , distance D may range from about 0.025 inches to about 0.075 inches. 
         [0025]      FIG. 10  illustrates yet another embodiment of a connection configuration between a flexible front plate  10  and a retaining plate  30 . In the illustrated embodiment, a separate end-supported beam  100  is provided in a defined finger  14  of the flexible front plate  10  near the outer diameter OD of the finger  14 . For example, without limitation, the end-supported beam  100  may be provided within about 0.025 inches to about 0.100 inches from the outer diameter OD. In the illustrated embodiment, a single weld location  80  is provided at or about a midpoint of the beam section  90  (which is provided between the end-supported beam  100  and the outer diameter OD of the finger  14 ). 
         [0026]    It is noted that while some exemplary connection or weld locations (such as those identified as elements  80 ) are illustrated in connection with several depicted embodiments, the weld locations can be provided in connection with every finger location, or instead only at a few locations. Also while multiple weld locations  80  may be shown, if desired, welding may instead be provided in as little as one location to hold the front plate  10  and the retaining plate  30  in position. Moreover, various combinations of connection configurations and methods may be employed. For instance, a front plate could be captured within a groove in the retaining plate, and a single spot weld could be used to weld portions of the two components together. 
         [0027]    The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and various modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to explain the principles of the invention and its practical application, to thereby enable others skilled in the art to utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.