Patent Publication Number: US-11649733-B1

Title: Flexible seal assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 16/005,044, filed Jun. 11, 2018, which claims priority to U.S. Provisional Application No. 62/518,487, filed Jun. 12, 2017, the entirety of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present application relates to flexible seal assemblies, and more specifically, flexible seal assemblies having a relatively low torsional rigidity and high longitudinal flexure to thereby allow the flexible seal assembly to flex between adjacent components and maintain a seal, even when movement between adjacent components occurs. 
     BACKGROUND 
     In many industrial applications, such as gas turbines and aerospace turbines, several components are assembled together in a circular and/or segmented fashion. These arrangements typically result in the creation of gaps between adjacent segments. Such gaps are generally undesirable, as they create paths for air and gas leaks that, if not filled or closed, decrease operation efficiency. 
     Historically, these gaps have been filled using cloth seals or laminate seals. However, both solutions provide limitations in one or more of flexure, durability, sealing, and temperature resistance. For example, problems associated with previously known seals used to fill gaps between adjacent components include leakage along the longitudinal axis, lack of durability (e.g., brittleness), increased number of potential leak paths, wear issues, lack of compliancy, and limited resiliency. 
     Accordingly, a need exists for improved sealing assemblies that reduce or eliminate some or all of these limitations. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary, and the foregoing Background, is not intended to identify key aspects or essential steps of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     Described herein are various embodiments of a flexible seal assembly suitable for use in applications such as gas turbines or aerospace turbines where a flat seal between adjacent components is required in order to improve operating efficiency. In some embodiments, the flexible seal assembly comprises one or more layers of a metal matrix sheet material, and a metal casing fully or partially encapsulating the one or more layers of the metal matrix sheet material. The metal matrix sheet material can be made from a plurality of segments of thin wire arranged in a random fashion to create a sheet structure, and which are then sintered together to form a semi-rigid sheet. The metal casing can be made of a metal alloy. 
     This composite structure provides a flexible seal assembly that has a relatively low torsional rigidity and high longitudinal flexure to thereby allow the flexible seal assembly to flex between adjacent components and maintain a seal, even when movement between adjacent components occurs. The low torsional rigidity/high longitudinal flexure also reduces wear to the components that come into contact with the seal assembly that can be caused by previously known rigid seal assemblies. Additionally, the casing protects the interior metal matrix sheet material to thereby improve the operational lifetime of the seal assembly, but without sacrificing the flexibility of the seal assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the disclosed flexible sealing assembly, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views, uncles otherwise specified. 
         FIGS.  1 A and  1 B  illustrate top, cross-sectional, and side views of two versions of a multi-layered flexible seal assembly according to various embodiments described herein; 
         FIG.  2    illustrates a flexible seal assembly according to embodiments described herein inserted in a slot provided in a component to be sealed according to various embodiments described herein; 
         FIG.  3    illustrates top, cross-sectional and side views of a multi-layered flexible seal assembly having an S-shaped casing according to various embodiments described herein; 
         FIG.  4    illustrates top, cross-sectional and side views of a multi-layered flexible seal assembly according to various embodiments described herein; and 
         FIGS.  5 A- 5 I  illustrate top, cross-sectional and side view of various flexible seal assemblies according to various embodiments described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are described herein more fully below with reference to the accompanying Figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, the embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following Detailed Description is, therefore, not to be taken in a limiting sense. 
     With reference to  FIG.  1 A , a flexible seal assembly  100  according to various embodiments described herein is illustrated. The flexible seal assembly  100  of  FIG.  1 A  includes three layers of metal matrix sheet material  110   a ,  110   b ,  110   c  stacked one on top of the other and sandwiched between a metal casing  120 , which includes an upper metal casing  120   a  and a lower metal casing  120   b . The layers of metal matrix sheet material  110   a ,  110   b ,  110   c  can have the same dimensions and shape such that edges of the layers of metal matrix sheet material  110   a ,  110   b ,  110   c  can be aligned when stacked together. The metal casing  120  provides a protective barrier on the top and bottom of the three layers of metal matrix sheet material  110   a ,  110   b ,  110   c , while the ends of the layers of metal matrix sheet material  110   a ,  110   b ,  110   c  are left exposed (see, e.g., Detail AD, which is an end view of the seal assembly  100 ). The sides of the layers of metal matrix sheet material  110   a ,  110   b ,  110   c  are also exposed (see, e.g., Detail AD), but the upper metal casing  120   a  and the bottom  120   b  do each include slanted overhangs  122   a ,  122   b  that partially protect the sides of the layers of metal matrix sheet material  110   a ,  110   b ,  110   c.    
     Each metal matrix sheet material layer  110   a ,  110   b ,  110   c  is generally comprised of multiple segments of thin wire arranged at random and sintered together to form a semi-rigid sheet material. The material of the thin wire used to create the shorter segments can generally be any suitable type of metal material and will typically have a diameter of less than 0.010 inches. The thin wire is cut into short segments, such as segments having an aspect ratio of around 20. For example, when the diameter of the thin wire is 0.010 inches, the length of the individual segments cut from the wire is typically in the range of 0.200 inches. 
     The thickness of a layer of the metal matrix sheet material is generally not limited, and may be as thin as approximately the two times the diameter of the wire segments used. The thickness of the metal matrix sheet material can be increased by using more segments piled on top of each other when the segments are randomly arranged to form the sheet structure. 
     The randomly arranged segments are sintered in order to bond together segments that contact one another. Sintering is generally carried out by using a heat-treating process. Any temperature can be used for the sintering step provided that the temperature is sufficient to bond together the metal segments without destroying the structural integrity of the wires. Similarly, the sintering can be carried out for any period of time provided that the bonding together of metal segments occurs. Other processing steps can also be used in the creation of the sheets, such as additional sintering steps and/or calendaring steps. Such additional processing steps can be used to achieve, for example, desired density, tensile strength, thickness and permeability. 
     The overall dimensions (x, y and z directions) of the metal matrix sheet material are generally not limited and may be selected based on the specific application in which the seal assembly will be used. In some embodiments, 3 feet by 3 feet sheets of metal matrix sheet material are prepared (with any suitable thickness), and smaller sections are cut from the larger sheets in order to provide the layers of metal matrix sheet material used in the seal assembly. 
     The upper casing  120   a  and the lower casing  120   b  of the casing  120  are generally formed of any suitable metal alloy. Metal alloys are suitable for use because they do not overly restrict the flexibility of the seal assembly while still providing sufficient protection to the metal matrix material layers  110   a ,  110   b ,  110   c . As discussed above, the sealing assembly  100  shown in  FIG.  1 A  provides an upper protective barrier and a lower protective barrier for the upper and lower surfaces of the stack of metal matrix material layers  110   a ,  110   b ,  110   c . The ends of the stack may be exposed while the sides are partially exposed. As shown in  FIG.  1 A , the sides of the upper and lower casings  120   a ,  120   b  may include inwardly slanted overhangs  122   a ,  122   b  to partially protect the sides of the metal matrix material layers. The angle of these slanted overhangs  122   a ,  122   b  is generally not limited, and may be from about 5° (i.e., practically parallel with the rest of the casing  120 ) to about 90° (i.e., at a right angle to the rest of the casing  120 ). In some embodiments, the slanted overhangs  122   a ,  122   b  are at an about 45° angle. 
     In some embodiments, the casings  120   a  and  120   b  are attached to the metal matrix material sheets  110   a ,  110   b ,  110   c  in order to create the final seal assembly  110  and keep the separate metal matrix material sheet layers of the seal assembly  100  together. Any manner of attaching the metal matrix material sheet layers can be used. In some embodiments, the attachment is via a mechanical fastening mechanism, such as a clip or vice. In some embodiments, the attachment is via a welding, fusion, brazing or sintering process. As shown in  FIG.  1 A , a series of spot welds  130  are used in order to attach together the upper casing  120   a , the metal matrix material layers  110   a ,  110   b ,  110   c  and the lower casing  120   b.    
     The sealing assembly  100  shown in  FIG.  1 B  is similar to the sealing assembly  100  shown in  FIG.  1 A , save for the use of only two metal matrix material layers  110   a ,  110   b . While  FIGS.  1 A and  1 B  show three layer and two layer structures, respectively, any number of metal matrix material layers can be used including one layer or more than three layers. 
       FIG.  2    illustrates the manner in which a seal assembly as described herein may be used in conjunction with components requiring sealing therebetween. A component of a turbine  200  is shown including a slot  201 . The seal assembly  100  from, for example,  FIG.  1 A or  1 B , can be inserted into the slot  201 . A second component (not shown) to be positioned adjacent component  200  includes a similar slot that receives the other side of the seal assembly  100 . In this manner, the seal assembly  100  blocks any gap that might exist or be formed between the adjacent components, which consequently improves operating performance of the, for example, turbine. The seal assembly  100  has a low torsional rigidity and high flexibility, and can therefore accommodate any movement of the components while still maintaining an effective seal and without damaging the components. 
     With reference to  FIG.  3   , an alternate embodiment of a seal assembly  300  is shown wherein the casing  310  is in the form of an S-shape such that an intermediate metal layer  310   a  is provided between the layers of metal matrix material  320   a ,  320   b . The material of the metal matrix material layers  320   a ,  320   b  and the casing  310  can be similar or identical to the material described above with respect to metal matrix material layers  110   a ,  110   b ,  110   c , and casing  120 . 
     Each metal matrix material layer  320   a ,  320   b  is provided within either the top or bottom portion of the S-shaped casing  310  and is retained within the casing  310  by angled end portions  311  of the S-shaped casing  310 . In such an embodiment, there may be no requirement for additional securement means, as the assembly stays together by virtue of the metal matrix material layers  320   a ,  320   b  being tucked within the upper and lower portion of the S-shaped casing  310  and the angled portion  311  maintaining the metal matrix material layers  320   a ,  320   b  within the upper and lower portions of the S-shaped casing. 
     While not required based on the self-retaining configuration of the embodiment shown in  FIG.  3   , the seal assembly  300  can further include means for attaching together the metal matrix layers  320   a ,  320   b  and the casing  310 , such as via a mechanical fastening mechanism (e.g., a clip or vice), welding, fusion, brazing or sintering process. 
     With reference to  FIG.  4   , another alternate embodiment of a sealing assembly  400  is shown wherein the metal matrix material layers  420   a  and  420  are formed with a protrusion and recess, respectively, to help mechanically link the two layers together. The material of the metal matrix material layers  420   a ,  420   b  and the casing  410  can be similar or identical to the material described above with respect to metal matrix material layers  120   a ,  120   b ,  120   c , and casing  110 . 
     In the embodiment shown in  FIG.  4   , metal matrix material layer  420   a  includes a protrusion  420   a - 1 , which can be made of locally accumulated segments of thin wire sintered together. Similarly, metal matrix material layer  420   b  includes a recess  420   b - 1  that is arranged and sized to receive the protrusion  420   a - 1  and thereby mechanically maintain the two layers together in at least a longitudinal direction. In other words, the protrusion  420   a - 1  and recess  420   b - 1  can prevent longitudinal sliding of the two layers away from each other. The seal assembly  400  also includes an upper casing  410   a  and lower casing  410   b.    
     While not required based on the self-retaining configuration of the embodiment shown in  FIG.  4   , the seal assembly  400  can further include means for attaching together the metal matrix layers  420   a ,  420   b  and the casing  410 , such as via a mechanical fastening mechanism (e.g., a clip or vice), welding, fusion, brazing or sintering process. 
       FIG.  5 A  illustrates another embodiment of a seal assembly wherein the metal matrix material layer  510  is a single layer. Additionally, the upper metal casing  520   a  and the lower metal casing  520   b  of the metal casing  520  includes slanted overhangs  522   a ,  522   b  as in  FIGS.  1 A and  1 B , but the metal matrix material layer  510  contacts the slanted overhangs  522   a ,  522   b  such that the metal matrix material layer  510  extends to the ends of the slanted overhangs  522   a ,  522   b , rather than providing a gap between the slanted overhangs as in  FIGS.  1 A and  1 B . 
     The seal assemblies shown in  FIGS.  5 B- 5 I  have a similar configuration to  FIG.  5 A , but further include a series of slits  501  formed through the seal assembly. As described in greater detail below, the slits  501  can be vertical or angled, and can have various sizes, shapes and geometries. The various slits  501  are provided to alter the rigidity of the sealing assembly and allow for more flexibility and torsional movement such that the seal assembly is able to move with the components with which the seal assembly is used. 
       FIG.  5 B  shows several rows of a series of straight line slits  501  aligned in a direction parallel with the longitudinal axis of the seal assembly. The slits  501  extend vertically into the seal assembly. 
       FIG.  5 C  shows a single continuous wave-like slit  501  formed across the length of the seal assembly. The slit  501  extends vertically into the seal assembly. 
       FIG.  5 D  is similar to  FIG.  5 C , but the single continuous wave-like slit  501  is formed at an angle into the seal assembly. 
       FIG.  5 E  shows a series of S-shaped slits  501  formed across the length of the seal assembly. The slits  501  extend vertically into the seal assembly. 
       FIG.  5 F  shoes a single continuous right-angle wave-like slit formed across the length of the seal assembly. The slit  501  extends vertically into the seal assembly. 
       FIG.  5 G  is similar to  FIG.  5 F , but the single continuous right-angle wave-like slit  501  is formed at an angle into the seal assembly. 
       FIG.  5 H  shows a series of slits  501  formed in a direction perpendicular to the longitudinal axis of the seal assembly and extending towards the center of the seal assembly from both sides of the seal assembly. Each slit  501  extending from one side of the seal assembly is aligned with a corresponding slit  501  extending from the opposite side of the seal assembly. Aligned slits  501  extending from opposite sides seal assembly do not contact each other or overlap. 
       FIG.  5 I  shows a series of slits  501  formed in a direction perpendicular to the longitudinal axis of the seal assembly and extending towards the center of the seal assembly form both sides of the seal assembly. Each slit  501  extending from one side of the seal assembly is offset from slits  501  extending from the opposite side of the seal assembly. The slits  501  extending from opposite sides of the seal assembly overlap but do not contact each other. 
     While shown separately from the seal assembly embodiments of  FIGS.  1 - 4   , any of the slits configurations shown in  FIGS.  5 B- 5 I  can be used in conjunction with any of the seal assembly embodiments shown in  FIGS.  1 - 4   . 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the scope of the invention. Accordingly, the invention is not limited except as by the appended claims. 
     Although the technology has been described in language that is specific to certain structures and materials, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific structures and materials described. Rather, the specific aspects are described as forms of implementing the claimed invention. Because many embodiments of the invention can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. 
     Unless otherwise indicated, all numbers or expressions, such as those expressing dimensions, physical characteristics, etc., used in the specification (other than the claims) are understood as modified in all instances by the term “approximately”. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each numerical parameter recited in the specification or claims which is modified by the term “approximately” should at least be construed in light of the number of recited significant digits and by applying rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass and provide support for claims that recite any and all sub-ranges or any and all individual values subsumed therein. For example, a stated range of 1 to 10 should be considered to include and provide support for claims that recite any and all sub-ranges or individual values that are between and/or inclusive of the minimum value of 1 and the maximum value of 10; that is, all sub-ranges beginning with a minimum value of 1 or more or ending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, and so forth) or any values from 1 to 10 (e.g., 3, 5.8, 9.9994, and so forth).