Abstract:
A seal includes a main body portion having fingers that extend outward to seal against the sides of one or more flexible conduit sections. The seal embodies several features that minimize the effect of compressing the seal over extended use. In one embodiment, the seal include a tab that isolates compression forces from the fingers. Other embodiments, include a recessed hinge point between the fingers and the main body. Still other embodiments, incorporate a material that fills the region between the fingers.

Description:
TECHNICAL FIELD 
       [0001]    The present invention pertains to bleed air systems for turbine engines, and more particularly, to seals used in conduit conveying bleed air to various components. 
       BACKGROUND OF THE INVENTION 
       [0002]    A large percentage of aircraft today, both commercial and military, utilize turbine propulsion units powered by two or more engines. Such aircraft divert air from the engines to supply various systems on the aircraft, like for example environmental control systems, which require a continuous supply of conditioned air. In other instances, bleed air is used to cool onboard equipment. Air bled from the engines can also be used to de-ice the leading edge of the wings. Still other systems on the aircraft can use air drawn from the engines in difference ways. 
         [0003]    To transport air bled from the engines to other areas of the aircraft, a conduit is used typically assembled from multiple tubular sections constructed from metal or other lightweight material. Air pressure in the conduit can reach up to and extend beyond 500 psig, with temperatures exceeding 1000° F. However, under typical operating conditions, nominal air pressure resides at about 50 psig and the temperature of the air is closer to 250° F. The conduit ranges in diameter from 1.00″ to 4.00″. 
         [0004]    The bleed air conduit requires specialized seals at various points in the system. Such points are typically marked by the interface between two or more adjacent conduit sections and/or where a component is connected to a section of the conduit. In aircraft, the conduit interface or conduit coupling is characterized by its ability to flex, which is important for bleed air systems in order to compensate for misalignments of the ductwork, elongation or contraction brought about by temperature changes, and/or movements of the engine or the aircraft structure during flight. 
         [0005]    In the current state of the art, conduit seals as shown in  FIG. 3 , encircle the conduit at the coupling. The intended use of seal  50  is to seal off the area between juxtaposed conduit sections. The seal  50  includes arms  51  that extend from a spine  53  contiguously formed into a ring, the configuration of which creates a concave region. The arms  51  angle away from a centerline axis C pa  for engaging the respective surfaces of the conduit sections. A spring  55  is included for added biasing of the arms  51  against the conduit surfaces. When compressed or preloaded and installed into the conduit, the seal  50  inhibits the flow of pressurized air through the coupling. 
         [0006]    During operation, vibration and movement between conduit sections contort and compress the seal  50  causing wear and fatigue. Compression force is focused on at least one particular area of the prior art seal  50 , namely the spine  53 . Repeated compression weakens the material and reduces the ability of the seal  50  to expand against the conduit surfaces. Even more critically, compression forces imposed on the seal  50  translate to the spring  55  and the arms  51 . As the conduit sections deflect to their extremities, the spring  55  may be over-compressed and deformed thereby reducing its ability or rendering it inoperative to energize the arms  51 . Spring failure often results. 
         [0007]    Accordingly, bleed air conduit seals  50  breakdown after so many hours of use. Technicians and flight mechanics routinely inspect and replace such seals  50 . The operating life of the seal  50  is generally shorter than the surrounding components, namely the various conduit sections circuitously routed throughout the craft. Considerable labor is devoted to the inspection and replacement of the seals. It would therefore be beneficial to incorporate a seal distinguished by an extended operating life cycle, and more particularly to a seal that isolates compression forces to a specific region. A primary purpose of the present invention is to provide such a device with its various attendant advantages. 
       BRIEF SUMMARY 
       [0008]    The embodiments of the present invention pertain to a device that isolates the critical components of the seal from force imposed from the surrounding structure, which may be flexible air conduit. More specifically, a cushion may be provided and installed between surfaces of the conduit that absorbs a majority of the impinging force, directing it away from the body of the seal and from the sealing projecting edges. 
         [0009]    In one embodiment, a seal for an air conduit coupling having first and second coupling portions includes a body portion, at least a first projecting edge extending from the body portion for substantially preventing the passage of air through the associated air conduit coupling, and means for isolating compression forces between the first and second coupling portions from impinging on the at least a first projecting edge. 
         [0010]    In one aspect of the embodiments of the subject invention, the means for isolating comprises a tab for absorbing compression forces between the first and second coupling portions thereby minimizing said compression forces from impinging on the at least a first projecting edge. 
         [0011]    In another aspect of the embodiments of the subject invention, the seal includes a biasing device operatively disposed to bias the at least a first projecting edge into sealing engagement with the air conduit coupling, wherein the biasing device may be a spring and more specifically a leaf spring constructed from metal, polymers and/or fibrous materials. 
         [0012]    In another aspect of the embodiments of the subject invention, the means for isolating is integrally fashioned with respect to the body portion. 
         [0013]    In yet another aspect of the embodiments of the subject invention, the at least a first projecting edge extends from the body portion in a first direction, and wherein the means for isolating comprises a tab extending from the body portion in a second or opposite direction. 
         [0014]    In still another aspect of the embodiments of the subject invention, the at least a first projecting edge is in resiliently deflectable connection with respect to the body portion. 
         [0015]    In even another aspect of the embodiments of the subject invention, the seal is comprised of material containing at least 5% graphite. 
         [0016]    In another aspect of the embodiments of the subject invention, the seal may include a depression or recess disposed between the at least a first projecting edge and the body portion defining a hinge point that isolates compression forces between the at least a first and second conduit portions from impinging on the at least a first projecting edge. 
         [0017]    In still yet another aspect of the embodiments of the subject invention, the seal includes a material disposed between the at least a first and second projecting edges, wherein the material at least partially encapsulates the biasing device. 
         [0018]    In another embodiment of the subject invention, a seal for an air conduit coupling having first and second coupling portions includes a body portion, at least a first projecting edge extending from the body portion for substantially preventing the passage of air through the associated air conduit coupling, a biasing device operatively connected to bias the at least a first projecting edge in sealing engagement with the air conduit coupling, and a recessed hinge point positioned between the at least a first projecting edge and the body portion for isolating compression forces between the first and second coupling portions from impinging on the biasing device. 
         [0019]    In one aspect of the embodiments of the subject invention, the body portion and the at least a first projecting edge are contiguously formed, and a hinge point comprises a recess formed at the interface of the body portion and the at least a first projecting edge. 
         [0020]    In another embodiment of the subject invention, a seal for an air conduit coupling having first and second coupling portions comprises a body portion, a first and at least a second projecting edge extending from the body portion for substantially preventing the passage of air through the associated air conduit coupling, a biasing device operatively connected to bias the first and the at least a second projecting edges in sealing engagement with the air conduit coupling, and a material disposed between the first and at least a second projecting edges, wherein the material at least partially encapsulates the biasing device. 
         [0021]    In another aspect of the embodiments of the subject invention, the material disposed between the first and at least a second projecting edges is resiliently deformable for energizing the first and the at least a second projecting edges into sealing engagement with the first and second coupling portions respectively, and may include at least in part Silicon. 
         [0022]    In another embodiment of the subject invention, an aircraft air bleed conduit includes at least a first conduit portion having a first conduit end defining an inner circumference, a second conduit portion having a second end received at least partially within the inner circumference of the first conduit end of the at least a first conduit portion, and a seal disposed between the at least a first conduit portion and the second conduit portion, wherein the seal comprises: a body portion, a first and at least a second projecting edge extending from the body portion for substantially preventing the passage of air between the at least a first and the second conduit portions, a biasing device operatively connected to bias the first and at least a second projecting edge in sealing engagement with the at least a first and the second conduit portions respectively, and a tab extending from the body portion and between the at least a first conduit portion and the second conduit portion for cushioning impact forces impinging on the biasing device. 
         [0023]    In another aspect of the embodiments of the subject invention, the seal further comprises: a resiliently deformable material disposed between the first and the at least a second projecting edges substantially encapsulating the biasing device. 
         [0024]    In still another aspect of the embodiments of the subject invention, the seal further comprises: at least a first hinge point disposed between either or both of the first projecting edge and the at least a second projecting and the body portion, and the position of the at least a first hinge point isolates compression forces between the at least a first and second conduit portions from impinging on the biasing device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a top silhouette view of an aircraft having turbine engines that bleed air for use in other areas of the aircraft according to the embodiments of the present invention. 
           [0026]      FIG. 2  is partial cutaway side view of bleed air conduit sections mounted within a bleed air system according to the embodiments of the present invention. 
           [0027]      FIG. 3  is a cutaway side view of a prior art seal used in the bleed air system of an aircraft. 
           [0028]      FIG. 4  is a cutaway side view of a seal mounted between first and second conduit sections according to the embodiments of the present invention. 
           [0029]      FIG. 4   a  is a cutaway side view of a seal mounted between first and second conduit sections according to the embodiments of the present invention. 
           [0030]      FIG. 5  is cutaway side view of a seal for use in a conduit channeling pressurized air according to the embodiments of the present invention. 
           [0031]      FIG. 5   a  is perspective view of a seal for use in a conduit channeling pressurized air according to the embodiments of the present invention. 
           [0032]      FIG. 6  is cutaway side view of another embodiment of a seal for use in a conduit channeling pressurized air according to the embodiments of the present invention. 
           [0033]      FIG. 6   a  is cutaway side view of yet another embodiment of a seal for use in a conduit channeling pressurized air according to the embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Referring now to the drawings wherein the showings are for purposes of illustrating embodiments of the invention only and not for purposes of limiting the same,  FIGS. 4 and 5  shows a seal, depicted generally at  10 . The seal  10  functions to substantially prevent the flow of air between components, and may be used in pumps, compressors, fuel controls, food processing equipment, and the like. In one exemplary embodiment, the seal  10  may be installed in the bleed air system  16  of a turbine engine aircraft  12 , as referenced in  FIGS. 1 and 2 . The system  16  may incorporate one or more conduits  17  originating from within the wings  11  of the aircraft  12  and/or from the fuselage  15 . The conduits  17  channel air bled from the engine  14  to other parts of the aircraft  12  in a manner similar to that described above. The seal  10  resides at the interface between components of the system  16 , in this case between multiple conduit sections. More specifically, the seal  10  may be installed between the outer surface of a first conduit section  21  and one or more inner surfaces of a second conduit section  22 . The seal  10  may also include a back up ring  8  designed to support the seal  10 . The back up ring  8  may be fabricated from a different material or from the same material as that of the seal  10  itself, which will be discussed further in a subsequent paragraph. It will be appreciated that the concentric configuration of conduit sections presently described and the positioning of the seal  10  relative thereto are exemplary in nature. Other configurations, of the conduit sections, the conduit interface and the seal  10 , will be contemplated without departing from the intended scope of coverage of the embodiments of the subject invention. It is emphasized here that the seal  10  is not limited to use only in bleed air systems. Rather, the novel aspects of the seal  10  can be used in a diversity of pressurized systems. 
         [0035]    With reference to  FIG. 2 , the first conduit section  21  has a substantially cylindrically shaped end  25  that is received within the circumference of a second substantially cylindrical conduit section  22 . As such, end  25  of the first conduit section  21  may be smaller than matching end  26  of the second conduit section  22 . End  26  of the second conduit section  22  may be fashioned with pockets or recesses  23  contoured to receive the seal  10 . Recess  23  defines an inner surface  24  of the second conduit section  22 . In one embodiment, the second conduit section  22  may include a retaining wall  29  that, at least in part, holds the seal  10  in place during use. It will of course be recognized that the retaining wall  29  functions to prevent axial movement of the seal  10  with respect to the conduit section  22 . 
         [0036]    With reference again to  FIG. 4 , during operation of certain systems, like for example bleed air systems on airplanes, the conduit sections  21 ,  22  move with respect to one another. In fact, certain aviation regulations may require that one conduit section move in relation to another throughout a range of movement. For example, one conduit section  21  may deflect axially with respect to another conduit section  22 . That is to say that a centerline axis of conduit section  21  may be skewed at different angles with respect to the centerline axis of conduit section  22 . In some instances, the conduit sections  21 ,  22  may deflect up to 3°. The conduit sections  21 ,  22  may also reciprocate one inside the other, and additionally may rotate with respect to each other. The seal  10  functions to substantially prevent the passage of air between the conduit sections despite being compressed and contorted. 
         [0037]    With reference now to  FIGS. 5 and 5   a,  a novel and inventive seal  10  is shown. In one embodiment, the seal  10  comprises a body portion  31 .  FIG. 5   a  is a perspective view that shows one configuration of the body portion  31 , which is annularly shaped. Fingers  33  extend from the body portion  31  in a first direction. In an exemplary, two fingers  33  are shown extending from the same side of the body portion  31 . A first finger  33   a  angles upward with respect to a centerline axis C and a second finger  33   b  angles in the opposite direction, or downward. At their extremities, the fingers  33  turn inward to form a retaining ledge  34 . While the figures depict the fingers  33  to be generally symmetrical about the centerline C, it is to be construed that any shape, length and angularity of the fingers  33  may be chosen as is appropriate for use with the embodiments of the subject invention. This includes symmetrical and asymmetrical configurations of the fingers  33  extending from the seal  10 . 
         [0038]    As depicted in the cross-sectional view of  FIG. 5 , the body portion  31  and the fingers  33  form a generally concave region  36 . In one embodiment, the fingers  33  may be constructed from an elastomeric material, which will be discussed further below. In this manner, the fingers  33  are resiliently deflectable, or resiliently deformable, with respect to the body portion  31 . That is to say that the material of the fingers  33  have memory wherein when deflected the fingers  33  have a tendency to return to their original position and shape. The fingers  33  therefore comprise projecting edges extending from the body portion  31  in a first direction for substantially preventing the passage of air through the region between one or more conduit sections, also termed conduit coupling. A biasing device  38  may be installed in the concave region  36  for use in energizing the fingers  33  into sealing engagement with the conduit surfaces. The biasing device  38  may incorporate a spring-like member, or spring  38   a.  The spring  38   a  may be constructed from metal or metal alloy. However, other substances may be utilized that have elastic properties suitable for energizing the fingers  33 , including but not limited to polymer materials and/or fibrous materials. In a manner similar to the annular configuration of the body portion  31 , the biasing device  38  may be contiguously formed around the entire circumference of the seal  10 . It will be appreciated by persons of ordinary skill in the art that any manner of installing the biasing device  38  into the seal  10  may be chosen with sound engineering judgment. This may include the manual assembly of individual components, as well as over molding processes. 
         [0039]    With reference to  FIG. 5   a,  in one embodiment, the seal  10  may be fashioned as a unitary article having a closed circumference. More specifically, the seal  10  may be circular in configuration. However, the seal  10  may also have an elliptical shape or alternatively a polygonal shape. In fact, the circumference of the seal  10  may have any configuration as is appropriate for sealing the region between various conduit sections. Additionally, the seal  10  may be constructed from one or more polymer materials. In an exemplary manner, the seal  10  may be constructed from moldable polymers or thermoplastics, and more specifically elastomers. One such polymer may include PTFE-based compounds (polytetrafluoroethylene). Other materials may include PEEK-based compounds (polyetheretherketone). Still, any polymer material may be used that is appropriate for constructing a seal used in a pressurized system having elevated temperatures. Accordingly, the seal  10  may be injection molded. Although, any molding process may be utilized as chosen with sound engineering judgment. It is noted here that additives or filler materials may also be incorporated into the seal  10 . One type of additive may include graphite. In one embodiment, as much as 10% graphite may be incorporated. Although, the amount of graphite may range from between substantially 0% to 25%. Still, any type and/or quantity of additive may be included that is suitable for use with the embodiments of the subject invention. 
         [0040]    With reference once again to  FIGS. 4 through 5   a,  a tab  40  may be extended from the body portion  31 . By way of example, the tab  40  may extend axially away from the body portion  31 . More specifically, the tab  40  may extend in the opposite direction from that of the fingers  33 . The tab  40  may be positioned substantially towards one side of the body portion  31 . As shown in the Figures, the tab  40  is positioned so as to extend between the outer surface of the first conduit section  21  and the retaining wall  29  of the second conduit section  22 . It will be appreciated that the tab  40  may be positioned at any location respective of the body portion  31  that is conducive to filling the region between the first and second conduit sections  21 ,  22 . It will also be understood that the particular shape of the tab  40  may follow the contour of the surfaces comprising conduit sections  21 ,  22  and retaining wall  29 , which may include angular and/or curved surfaces. In fact, any shape of the tab  40  may be chosen as is appropriate for use with the embodiments of the subject invention. 
         [0041]    Referring now to a cross section of the seal  10  shown in  FIG. 4   a,  the tab  40  may have a thickness T tab . As mentioned above, the tab  40  extends into the region between the outer surface of the first conduit section  21  and the end of retaining wall  29 . The difference between the thickness T tab  and the distance between the first conduit section  21  and the retaining wall  29  define a tab gap  63 . The thickness T tab  may be generally smaller than the nominal distance between the first conduit section  21  and the retaining wall  29 . In other words, the tab  40  has a slip fit with respect to the first and second conduit sections  21 ,  22 . Additionally, the body portion  31  has a thickness T body . The body portion  31  may reside between the outer surface of the first conduit section  21  and the inner surface of the second conduit section  22 , or the recess  23 . A body gap  65  is defined as the difference between the thickness T body  of the body portion  31  and the distance between the first and second conduit sections  21 ,  22 . The tab gap  63  may be smaller than the body gap  65 . In one embodiment, the tab gap  63  may be smaller than the body gap  65  through a range extending from substantially zero to 0.100 inch. More specifically, the tab gap  63  may be smaller than the body gap  65  by substantially 0.050 inch. It is noted here that the difference in gaps  63 ,  65  may depend on the composition of the seal material. Accordingly, the range of differences in gaps  63 ,  65  may exceed 0.100 inch. Still, any difference between the gaps  63 ,  65  may be chosen with sound engineering judgment. Persons of ordinary skill in the art will understand that the thickness T tab  of the tab  40  will be sized so as not to inhibit the ability of the fingers  33  to sealingly engage the respective surfaces of the first and second conduit sections  21 ,  22 . 
         [0042]    In operation, the tab  40 , in relation to the body portion  31 , functions as a cushion to isolate compression forces imposed on the seal  10 . That is to say that when, in a particular region around the circumference of the coupling, the distance between the first and second conduit section  21 ,  22  narrows, due to movement in the system  16 , the tab  40  is compressed before the body portion  31 . It may be the case that the body portion  31  is still be compressed. However, as the tab  40  is compressed further and further, resistance to the narrowing conduit sections will increase and as a result the majority of the impinging force will be imposed onto the tab  40 . Accordingly, the body portion  31  and the region proximal to the fingers  33 , also known as the hinge point, will be compressed fewer times and with lesser magnitude. In this manner, as the elasticity of the tab  40  deteriorates, the material of the body portion  31  remains largely unaffected by repeated compression. 
         [0043]    With reference now to  FIG. 6 , another embodiment of the subject invention will now be discussed. As noted above, force from compression of the body portion  31  indirectly translates to the fingers  33  and to the biasing device  38 . Force impacts the fingers  33  most when the fingers  33  extend directly from the upper and lower planes of the body portion  31 . To reduce the effect of the compression forces, the connection points of the fingers  33  with respect to the body portion may be moved respectively closer to the centerline axis C of the seal  10 . Stating it another way, the hinge points  70  of the fingers  33  are moved closer to the centerline axis C of the seal  10 . This effectively creates region devoid of material, i.e. a recess or trough  73 , in the upper and lower surfaces of the seal  10 . It is noted that any lateral position of the fingers  33  with respect to the centerline axis C of the seal  10  may be chosen as is appropriate for use with the embodiments of the subject invention. It is also noted that placement of the fingers  33  may not be symmetrical with to the centerline axis C of the seal  10 . In fact, the fingers  33 , either separately or together, may be positioned at any location on the side of the body portion  31 . 
         [0044]    With reference to  FIG. 6   a,  another embodiment of the subject invention will now be discussed. As described above, the configuration of the body portion  31  and the fingers  33  defines an interior region or concave region  36 , into which the biasing device  38  may be disposed. The concave region  36  may be filled with a material  78  that encapsulates the biasing device  38 . In an exemplary manner, the concave region  36  may be substantially filled with an elastomeric substance. One example of an elastomeric substance may include Silicon. Alternatively, the encapsulating material  78  may have the same composition as that the body portion  31  and/or fingers  33 . The encapsulating material  78  may be applied after insertion of the biasing device  38 . Overmolding techniques may be used to construct the seal  10 . Still, any manner of fashioning a seal  10  with encapsulating material  78  may be chosen with sound engineering judgment. The encapsulating material  78  may function as an additional energizer to the fingers  33 . When compressed, the encapsulating material  78  will have a tendency to spring back further assisting to bias the fingers  33  into sealing engagement with the conduit surfaces. It is noteworthy to mention that should the biasing device  38  breakdown and fragment, the encapsulating material  78  will prevent the pieces from being introduced into the air stream. 
         [0045]    The invention has been described herein with reference to the disclosed embodiments. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalence thereof.