Abstract:
A roll-up door seal that may be monolithically formed from a single material of uniform density. The seal is sized and adapted to assemble to a standard roll-up door frame without a separate or dedicated frame structure. The seal provides redundant sealing surfaces, positioned to cooperate with both the door and door frame, which ensure an effective and durable fluid tight seal between the cargo space enclosed by the roll-up door and the ambient environment. The seal may be produced by extrusion from a flexible, weather resistant material such as EPDM, thereby providing a low cost solution for sealing roll-up doors having industry standard door frame constructions. The seal is firmly engageable with the door frame, such that the seal may be installed with little or no secondary fixation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit under Title 35, U.S.C. Section 119(e) of U.S. Provisional Patent Application Ser. No. 61/779,336, filed Mar. 13, 2013 and entitled ROLL-UP DOOR SEAL, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/697,937, filed Sep. 7, 2012 and entitled ROLL-UP DOOR SEAL, the entire disclosures of which are hereby expressly incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to seals, and in particular, to seals that are adapted to seal roll-up type doors, such as cargo vehicle doors, garage and cargo bay doors, etc. 
         [0004]    2. Description of the Related Art 
         [0005]    Cargo trucks are sometimes provided with “roll-up” type cargo doors which raise and lower to selectively provide access to the cargo space of the truck. Such roll-up doors typically include a series of horizontal door panels hingedly connected to one another such that each panel is pivotable with the respect to the next adjacent panel about a horizontal hinge axis. As the roll-up door is raised, the panels progressively shift from a vertical orientation to a substantially horizontal orientation as the panels move inwardly away from the top of the door frame. To facilitate this function, rollers attached to the roll-up door typically ride within tracks disposed at each side of the door frame, with the tracks running vertically along the sides of the door frame and curving away from the top of the door frame to extend inwardly. 
         [0006]    Seals may be provided along either side of roll-up door assemblies to inhibit ingress of water, smoke, particulates, or the like into the cargo space when the roll-up door is closed. In some cases, such seals are affixed to the door frame via fasteners, which may be coupled directly to the body of the seal or to a frame structure built around the seal. These seal arrangements hold a flexible portion of the seal against the outer surface of the roll-up door when the door is in a closed position. 
         [0007]    Other roll-up door seals utilize specially designed door frames which accommodate custom-made, correspondingly shaped seal structures. These special seals may fit within the specially designed door frame structure to retain the seal at a desired position and orientation, but are not compatible with standard roll-up door frames or with other custom door frames. 
         [0008]    Still other seals utilize multi-density cross-sectional profiles, including a relatively high density seal portion that can be press fit into a seal receiving area of a frame, and a lower density seal portion that is more flexible and bear against the roll-up door when the door is in the closed position. Such seals are typically made from polyvinyl chloride (PVC) with differing durometer values among the different seal portions. 
         [0009]    While known roll-up door seals may be effective, it is desirable to minimize the cost and complexity of a roll-up door seal design, while also providing a reliable, long-lasting and fluid-tight seal between the roll-up door and the surrounding environment. 
       SUMMARY 
       [0010]    The present disclosure provides a roll-up door seal that may be monolithically formed from a single material of uniform density. The seal is sized and adapted to assemble to a standard roll-up door frame without a separate or dedicated frame structure. The seal provides redundant sealing surfaces, positioned to cooperate with both the door and door frame, which ensure an effective and durable fluid tight seal between the cargo space enclosed by the roll-up door and the ambient environment. The seal may be produced by extrusion from a flexible, weather resistant material such as EPDM, thereby providing a low cost solution for sealing roll-up doors having industry standard door frame constructions. The seal is firmly engageable with the door frame, such that the seal may be installed with little or no use of secondary fixation. 
         [0011]    In one form thereof, the present disclosure provides a seal for use in conjunction with a roll-up door and door frame, the seal including a coupling body having a seating surface and an exposed surface opposite the seating surface, a pair of opposed side surfaces extending between the seating surface and the exposed surface, a longitudinal body axis extending from the seating surface to the exposed surface between the pair of opposed side surfaces; and a plurality of securement ribs extending from each of the side surfaces, the plurality of securement ribs having a longitudinal extent defining a longitudinal rib axis, the longitudinal rib axis defining an acute angle with the longitudinal body axis, the acute angle opening toward the exposed surface. The seal further includes a main sealing lobe extending from the exposed surface of the coupling body, the main sealing lobe having an arcuate cross-sectional profile defining a concave inner surface and an opposing convex outer surface such that the main sealing lobe is adapted to bias against an adjacent door surface; and a secondary sealing lobe extending from an outwardly facing surface of the main sealing lobe, such that the secondary sealing lobe is positioned to bias against a frame surface opposing the adjacent door surface. 
         [0012]    In another form thereof, the present disclosure provides a seal arrangement including: a seal including a coupling body defining a longitudinal body axis and having a plurality of securement ribs extending from the coupling body, the plurality of securement ribs having a longitudinal extent defining a longitudinal rib axis, the longitudinal rib axis defining an acute angle with the longitudinal body axis; a main sealing lobe extending from the coupling body, the main sealing lobe having an arcuate cross-sectional profile defining a concave inner surface and an opposing convex outer surface; and a secondary sealing lobe extending from the convex outer surface of the main sealing lobe. The seal arrangement also includes a door frame having a seal receiving space defining a seal receiving space width, the coupling body of the seal defining a coupling body width which cooperates with the plurality of securement ribs to define an interference fit with the seal receiving space width, such that the seal is securely receivable in the door frame with the main sealing lobe and the secondary sealing lobe protruding outwardly from the seal receiving space; a roller track fixed to the door frame; and a roll-up door including rollers received in the roller track and operable to facilitate movement of the roll-up door between an open position and a closed position, the roll-up door having an outer surface. The main sealing lobe is in contact with the outer surface of the roll-up door when the roll-up door is in the closed position, such that the main sealing lobe is resiliently deformed to bias against the outer surface. The secondary sealing lobe is resiliently deformed to biasing against a surface of the door frame opposite the outer surface of the roll-up door when the main sealing lobe is resiliently deformed. 
         [0013]    In yet another form thereof, the present disclosure provides a method of installing a seal into a door frame of a roll-up door, the method including: advancing a body of the seal along a lateral direction, toward a sidewall of a roll-up door frame disposed along a lateral edge of the roll-up door; and pressing the body of the seal along the lateral direction into a seal receiving space formed in the roll-up door frame, such that the body of the seal is captured in the seal receiving space formed in the roll-up door frame. A first sealing lobe protrudes outwardly from the seal receiving space after the step of pressing the body of the seal, and a second sealing lobe protrudes outwardly from an outer surface of the first sealing lobe. The first sealing lobe is curved toward an outer surface of the roll-up door such that the first sealing lobe resiliently deforms to bias against the outer surface of the roll-up door when the roll-up door is placed in a closed position. The second sealing lobe extends toward a flange formed in the roll-up door frame opposite the outer surface of the roll-up door, such that the second sealing lobe resiliently deforms to bias against the flange when the roll-up door is placed in the closed position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a rear perspective view of a cargo truck including a roll-up door fitted with seals made in accordance with the present disclosure; 
           [0016]      FIG. 2  is a cross-sectional view of an exemplary seal made in accordance with the present disclosure; 
           [0017]      FIG. 3  is a plan, cross-sectional view of the seal shown in  FIG. 2 , illustrating assembly of the seal to a roll-up door frame; 
           [0018]      FIG. 4  is a plan, cross-sectional view, taken along line  3 - 3  of  FIG. 1 , illustrating the seal of  FIG. 3  after assembly to the roll-up door frame; 
           [0019]      FIG. 5  is a plan, cross-sectional view, taken along line  4 - 4  of  FIG. 1 , illustrating the seal of  FIG. 2  when the roll-up door is in the closed position; 
           [0020]      FIG. 6  is a cross-sectional view of another exemplary seal made in accordance with the present disclosure; and 
           [0021]      FIG. 7  is a plan, cross-sectional view of the seal shown in  FIG. 6 , taken along line  4 - 4  of  FIG. 1 , illustrating the seal configuration when the roll-up door is in the closed position. 
           [0022]      FIG. 8  is a cross-sectional view of yet another exemplary seal made in accordance with the present disclosure; 
           [0023]      FIG. 9  is a plan, cross-sectional view of the seal shown in  FIG. 8 , taken along line  4 - 4  of  FIG. 1 , illustrating the seal configuration when the roll-up door is in the closed position; and 
           [0024]      FIG. 10  is an elevation view of a portion of a roll-up door frame including a seal made in accordance with the present disclosure. 
       
    
    
       [0025]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an exemplary embodiment of the invention, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION 
       [0026]    Turning now to  FIG. 1 , seals  10  are shown installed at either side of roll-up door frame  12 , which is positioned at the rear of cargo box  22  mounted to truck  14 . Seals  10  may be identical structures, but are arranged as mirror images of one another so as to have main sealing lobes  40  extending inwardly toward cargo space  20 , as described in further detail below. Roll-up door  16  includes a plurality of door panels  18  hingedly connected to one another such that each door panel  18  is pivotable about a horizontal axis. In the illustrated embodiment of  FIG. 1 , roll-up door  16  is shown in a partially closed configuration, with seals  10  partially deformed into a sealing configuration in the area where roll-up door  16  is closed. 
         [0027]    When door  16  is open, cargo space  20  is accessible through the aperture defined by door frame  12 , and door panels  18  are disposed within cargo box  22  such that door panels  18  are all substantially parallel to the roof of cargo box  22 . In the closed configuration, door panels  18  of roll-up door  16  are vertically oriented (as shown in  FIG. 1  with respect to some of the panels  18 ), such that roll-up door  16  blocks access to cargo space  20  from outside cargo box  22 . As described in detail below, seals  10  bear against outer surfaces  50  of door panels  18  to provide a fluid tight seal between cargo space  20  of cargo box  22  and the surrounding environment. 
         [0028]      FIG. 2  illustrates a cross-sectional profile of seal  10  in an uncompressed state, after manufacture and prior to installation within door frame  12  ( FIG. 3 ). Seal  10  includes coupling body  24  defining longitudinal axis A 1 , which may also be an axis of symmetry for coupling body  24 . Axis A 1  extends along insertion direction D I , shown in  FIG. 3 , which is the direction of assembly of seal  10  to door frame  12 , as described in further detail below. Coupling body  24  tapers along axis A 1  from exposed surface  26  toward seating surface  28 , such that side surfaces  30 ,  32  define angle θ therebetween. As illustrated, angle θ is measured without taking into account securement ribs  34 , which extending outwardly from each of side surfaces  30 ,  32 . In an exemplary embodiment, angle θ may be as little as zero, 5 or 10 degrees or may be as large as 20, 25 or 30 degrees, or may be any value within any range defined by any of the foregoing values. In one particular exemplary embodiment, angle θ is about 4 degrees. 
         [0029]    Seating surface  28  has a generally rounded profile, as shown in  FIG. 2 , to further facilitate initial insertion of coupling body  24  into seal receiving space  36 . Exposed surface  26 , disposed opposite seating surface  28 , is substantially flat (i.e., planar) to facilitate flush mounting with the adjacent edge of a flange  58  of roller track  56 , as shown in  FIGS. 4 and 5  and described in further detail below. 
         [0030]    Securement ribs  34  are elongate structures as viewed in the cross section of  FIG. 2 , and therefore each define a longitudinal axis A 2 . Each axis A 2  forms an acute angle α with respect to axis A 1  of coupling body  24 , with each of securement ribs  34  configured such that angle α opens away from insertion direction D I  and toward exposed surface  26  of coupling body  24 . As described in further detail below, this configuration allows securement ribs  34  to easily deform when coupling body  24  is seated within seal receiving space  36  ( FIGS. 3 and 4 ), while also resisting removal of coupling body from seal receiving space  36 . In the interest of drawing clarity, the longitudinal axis A 2  of securement ribs  34  is shown for only one of securement ribs  34  on each of side surfaces  30 ,  32 , it being understood that the other securement ribs  34  also define respective axes A 2  forming angle α with respect to the longitudinal axis A 1  of coupling body  24 . In an exemplary embodiment, angle α may be as little as 45, 55 or 65 degrees or may be as large as 75, 85 or 90 degrees, or may be any value within any range defined by any of the foregoing values. In one particular exemplary embodiment, angle α is about 67 degrees. 
         [0031]    In the illustrated embodiment of  FIG. 2 , three securement ribs  34  are provided on each of side surfaces  30 ,  32 . However, it is contemplated that a larger or smaller number of ribs  34  may be provided to decrease or increase the securement of coupling body  24  within seal receiving space  36 , respectively, as required or desired for a particular application. In an exemplary embodiment, securement ribs  34  are sized and spaced from one another such that each of securement ribs can deform or “fold” down, in the direction of exposed surface  26  of coupling body  24 ) to abut the adjacent side surface  30  or  32  upon installation of seal  10 . Aperture  38  may also be formed within coupling body  24  to facilitate deformation thereof during installation of seal  10 , as also described below. 
         [0032]    Extending away from exposed surface  26  is main sealing lobe  40 , as best seen in  FIG. 2 . As illustrated, main sealing lobe  40  has a generally arcuate profile in cross-section, with an inner surface  42  forming an arcuate continuation of side surface  30 . When seal  10  is assembled to door frame  12 , side surface  30  is the inwardly facing surface of coupling body  24 , i.e., the surface facing toward the enclosed cargo space  20  of cargo box  22 . Thus, the illustrated position and arrangement of main sealing lobe  40  near inward side surface  30  biases sealing lobe  40  toward door panels  18  when roll-up door  16  is positioned closed, as shown in  FIG. 5  and further described below. 
         [0033]    Opposite inwardly facing surface  42  of main sealing lobe  40  is outwardly facing surface  44 , which has secondary sealing lobe  46  protruding therefrom. In the illustrative embodiment of  FIG. 2 , main sealing lobe  40  has a substantially constant thickness T M  throughout its arcuate extent, while secondary sealing lobe  46  has a generally triangular profile with a steadily decreasing thickness from the wide base of sealing lobe  46  (at its intersection with main sealing lobe  40 ) to the narrower tip  48  of secondary sealing lobe  46  (i.e., the point on sealing lobe  46  furthest from outer surface  44  of main sealing lobe  40 ). 
         [0034]    Assembly of seal  10  to door frame  12  is illustrated in  FIG. 3 . Seal  10  is received within seal receiving space  36  such that main sealing lobe  40  is positioned to bear against door panel  18  while secondary sealing lobe  46  bears against an inner surface  54  of flange  52  of door frame  12 . Seal receiving space  36  is a generally rectangular void (as viewed in the plan cross-sectional view of  FIG. 3 ), bounded on three sides by structures of door frame  12  and open on the fourth side. Opposite the open end of seal receiving space  36 , sidewall  62  of door frame  12  forms the “bottom” or base of seal receiving space  36 , against which seating surface  28  bears upon assembly of seal  10  to door frame  12  ( FIG. 4 ). Flange  58  of roller track  56  forms an inward wall of seal receiving space  36 , while flange  52  of door frame  12  forming the opposing outward wall. 
         [0035]    In certain exemplary embodiments, roller track  56  is fixedly attached to door frame  12 , such as by welding, riveting or other fixed attachment, such that a plurality of rollers  64  connected to door panels  18  via axles  70  ride within roller track  56  as door  16  is raised and lowered ( FIG. 1 ). Door frame  12  may be provided in a standard size and arrangement with roller track  56  affixed thereto in a standard configuration to accommodate mass produced roll-up doors  16  and rollers  64 . 
         [0036]    Seal receiving space  36  defines width W 1  between outwardly facing surface  60  of track flange  58  and the opposing inwardly facing surface  54  of frame flange  52 . In an exemplary embodiment in the context of roll-up cargo truck doors (such as door  16  shown in  FIG. 1 ), width W 1  may be between 0.5 inches and 1 inch. For other applications in other contexts, the overall profile shown and described herein may be scaled up or down to provide seals usable for other door frame sizes. In one exemplary embodiment, door frame  12  defines width W 1  of 0.88 inches, and the corresponding width of body  24  of seal  10  is about 0.74 inches wide at seating surface  28  and 0.82 inches wide at exposed surface  26 . In this exemplary embodiment, securement ribs are each between 0.06 inches and 0.1 inches wide, and are about 0.25 inches long as measured along axis A 2 . In this exemplary embodiment, the overall length of seal  10  (corresponding to the height of the sides of door frame  12  and shown in  FIG. 1 ) may be about 110 inches. 
         [0037]    As noted below, seal  10  may be provided in one or more standard sizes to accommodate various industry standard geometries for door frame  12 . More particularly, body  24  of seal  10  may be sized and configured to be received within a standard size seal receiving space  36 , while main sealing lobe  40  and secondary sealing lobe  46  are sized and configured to occupy the space between frame flange  52  and door panels  18 . As further described below, lobes  40 ,  46  may be specifically arranged to fill in a gap having width W 2  between outer surface  50  of door panel  18  and inwardly facing surface  54  of frame flange  52 , while providing a secure sealing arrangement therewithin. 
         [0038]    Assembly of seal  10  to door frame  12  along insertion direction D I  ( FIG. 3 ) can be accomplished quickly and efficiently. In an exemplary assembly method, body  24  of seal  10  is advanced along insertion direction D I  such that seating surface  28  of body  24  forms the leading edge of seal  10  advancing into seal receiving space  36 . The rounded outer profile of seating surface  28  facilitates initial insertion between flange  58  of roller track  56  and flange  52  of door frame  12 . As coupling body  24  is further advanced along insertion direction D I , the first pair of securement ribs  34  (i.e., those securement ribs  34  which are closest to seating surface  28 ) deflect toward side surfaces  30 ,  32 , respectively. This initial deflection is facilitated by the tapered profile of side surfaces  30 ,  32 , which cooperate to define angle θ ( FIG. 3 ) therebetween. 
         [0039]    Further advancement of coupling body  24  along direction D I  into seal receiving space  36  deflects the remaining securement ribs  34  as respective pairs of ribs  34  come into contact with frame flange  52  and track flange  58 . As the width between side surfaces  30 ,  32  increases along the tapered outer profile of body  24 , body  24  is more and more tightly received within seal receiving space  36 . To accommodate the eventual interference fit between such wider body portions and seal receiving space  36 , aperture  38  may compress from a circular to ellipsoid configuration as shown in  FIG. 4 . 
         [0040]    In one exemplary embodiment, width W 1  is equal to about 0.88 inches. As noted above, the corresponding width of body  24  for this exemplary embodiment is about 0.74 inches at seating surface  28 , excluding the adjacent securement ribs  34 , which facilitates initial insertion of body  24  into seal receiving space  36 . However, the final width of body  24  adjacent exposed surface  26  is about 0.82 inches, which cooperates with the about 0.1 inch thick securement ribs  34  to create an interference fit. Thus, the material of body  24  must be deformed to fully seat body  24  within seal receiving space  36 . When body  24  is fully received within seal receiving space  36 , seating surface  28  contacts sidewall  62  of door frame  12 , all of securement ribs  34  are deflected toward their respective side surfaces  30 ,  32 , coupling body  24  is slightly compressed such that aperture  38  is slightly deformed, and exposed surface  26  is substantially flush with the edge of track flange  58 . This fully assembled configuration is illustrated in  FIG. 4 . 
         [0041]    Although body  24  may be easily received within seal receiving space  36 , a much greater force is required to remove body  24  therefrom. This insertion/removal force differential results from the orientation of securement ribs  34  with respect to longitudinal axis A 1  of coupling body  24 , and therefore with respect to insertion direction D I  ( FIG. 3 ). 
         [0042]    More particularly, as noted above, securement ribs  34  each define acute angle α with respect to longitudinal axis A 1 , such that angle α opens away from seating surface  28  and toward exposed surface  26 . Upon insertion of coupling body  24  into seal receiving space  36 , this angular arrangement allows securement ribs  34  to deflect toward exposed surface  26  easily and with minimal frictional resistance. However, if coupling body  24  is pulled along a removal direction opposite insertion direction D I , securement ribs  34  bear against inwardly facing surface  54  of frame flange  52  and outwardly facing surface  60  of track flange  58 , respectively. Along this removal direction, angle α defined by securement ribs  34  serves to urge securement ribs  34  to expand away from side surfaces  30 ,  32 , respectively, rather than urging ribs  34  toward contact therewith. This expansion effectively increases the overall width of coupling body  24 , thereby increasing the level of friction between coupling body  24  and surfaces  54 ,  60  of flanges  52 ,  58 , respectively. 
         [0043]    Thus, the force required to remove coupling body  24  from seal receiving space  36  is substantially higher than the force required to insert coupling body  24  into seal receiving space  36  along insertion direction D I . This force differential allows seal  10  to be effectively used in conjunction with door frame  12  with little or no use of adhesives, fasteners, or other secondary fixation. Using only the material of coupling body  24 , firm securement of seal  10  to door frame  12  can be effected by pushing the coupling body  24  into the seal receiving space  36 . In the exemplary embodiment shown in  FIG. 10 , for example, only the top portion of seal  10  (i.e., the portion near the curved portion of roller track  56 ) is secured within door frame  12  by secondary fixation, such as adhesive. The remainder of seal  10  extending downwardly below such curved portion may be secured only by interaction between coupling body  24  and seal receiving space  36 . 
         [0044]    In one exemplary embodiment, seal  10  is monolithically formed from EPDM (ethylene propylene diene monomer) rubber having durometer  55 . In other exemplary embodiments, the durometer of the seal material may be as little as 40, 50 or 60 or may be as large as 65, 75 or 85, or may be any value within any range defined by any of the foregoing values. EPDM rubber is highly resistant to degradation from weather and sun, while also being sufficiently soft and pliable to create an effective seal between cargo space  20  of cargo box  22  and the surrounding ambient environment. Accordingly, this material has proven ideal for use with roll-up doors used in cargo trucks and other demanding outdoor environments. 
         [0045]    In the installed configuration of  FIG. 4 , main sealing lobe  40  and secondary sealing lobe  46  remain in their undeformed state due to the absence of roll-up door  16  at the location of the  FIG. 4  cross-section (as shown in  FIG. 1 ). As roll-up door  16  is advanced from the open to closed position, sealing lobes  40 ,  46  are progressively deformed into a sealing configuration along the extent of seal  10 . In an exemplary embodiment shown in  FIG. 10 , roll-up door frame  12  includes extension  72 , which abuts and aligns with outwardly facing surface  50  of roller track  56  to extend seal receiving space  36  upwardly past the point where track flange  58  of roller track  56  begins its inward bend into cargo space  20 . This effective lengthening of seal receiving space  36  allows seal  10  to be made longer and to extend substantially above the initial inward bend of roller track  56 , such that the first point of contact between the leading edge of door panel  18  and main sealing lobe  40  is substantially spaced away from the end of seal  10 . This in turn prevents sealing lobe  40  from “folding over” upon first contact by panel  18  of door  16 , and promotes proper deformation of lobe  40  into its sealing configuration as described in further detail below. 
         [0046]    After initial deformation of sealing lobe  40 , outer surfaces  50  of door panels  18  successively come into contact with tip  66  of main sealing lobe  40  further and further down the length of seal  10 . This “zipper” effect progressively forces lobe  40  outwardly (i.e., in a direction away from cargo space  20  of cargo box  22 ), which in turn advances tip  48  of secondary sealing lobe  46  into contact with inwardly facing surface  54  of frame flange  52  as illustrated in  FIG. 5 . Lobes  40 ,  46  are sized and configured to occupy a space between door panel  18  and frame flange  52  that is slightly larger than width W 2 , such that slight compression and deformation of lobes  40  and  46  occurs. This compression forms a pair of firm, fluid-tight seals between cargo space  20  and the ambient environment around cargo box  22 . 
         [0047]    Because lobes  40 ,  46  are forcibly deformed into their sealing configurations shown in  FIG. 5 , the resiliency of the material of seal  10  serves to bias tips  66 ,  48  of lobes  40 ,  46  toward contact with their respective sealing surfaces  50 ,  54 . This spring-like bias force maintains the redundant pair of fluid-tight seals formed by seal  10 , even if movement or vibration of door panels  18  and/or door frame  12  occurs (such as while truck  14  is moving). Moreover, the deformation of main sealing lobe  40  serves to “push” secondary sealing lobe  46  into its sealing arrangement, which in turn “pushes back” against main sealing lobe  40 . In this way, sealing lobes  40 ,  46  act as mutually opposed biasing elements urging one another into sealing contact with their mutually opposed sealing surfaces  50 ,  54  respectively. Such biased contact between lobes  40 ,  46  and the adjacent sealing surfaces  50 ,  54  ensures that a lasting, durable fluid-tight seal will form even as the material of seal  10  becomes weathered over time. 
         [0048]    The amount of bias force provided by main sealing lobe  40  toward outer surface  50  of door panel  18  can be raised or lowered by changing the size and geometry of lobe  40 . For example, thickness T M  ( FIG. 2 ) may be increased to elevate the biasing force, or decreased to reduce the biasing force. In an exemplary embodiment designed for a seal receiving space  36  having width W 1  of 0.88 inches and a door frame arrangement defining width W 2  of 0.688 inches (with a tolerance of +/−0.063 inches), thickness T M  is 0.19 inches. 
         [0049]    Another variable affecting the biasing force is the undeformed radius of curvature R defined by lobe  40  (shown in  FIG. 2  as radius R at inwardly facing surface  42 ). If radius R is increased, the biasing force will decrease because the amount of material deformation will be reduced. Conversely, a decrease in radius R will cause an increase in material deformation and a concomitant increase in biasing force. As biasing force increases, sealing deformation and the ability of lobe  40  to span width W 2  increases. In the exemplary embodiment discussed above, radius R is about 0.5 inches. In the exemplary embodiments shown in  FIGS. 6-9  and described in detail below, radii R 100 , R 200  are 2.3 about inches. For larger or smaller seal arrangements, such as those having larger or smaller width W 2 , the overall size of lobe  40  will increase accordingly. However, the overall thickness of lobe  40  may remain substantially constant. 
         [0050]    Similarly, secondary sealing lobe  46  may be changed in size and thickness to provide greater or lesser biasing force against inwardly facing surface  54  of frame flange  52 . In the exemplary embodiment referenced above for a width W 1  of 0.88 inches for seal receiving space  36  and width W 2  of 0.688 to 0.748 inches, lobe  46  may extend an appropriate distance away from outwardly facing surface  44  of lobe  40 , measured as the shortest distance from the extrapolated outer surface  44  to the end of tip  48  of lobe  46 . In the case of seal  10 , this distance may be about 0.5 inches. Lobe  46  may also define an overall width at the base thereof equal to about 0.38 inches. The overall length and/or width dimensions can be increased to increase the biasing force provided by lobe  46 , or may be decreased to decrease such biasing force. Although lobe  46  is shown as being made of solid material in  FIGS. 2-5 , an aperture may be provided therein to reduce the biasing force provided by lobe  46 . 
         [0051]    In an exemplary embodiment, lobes  40  and  46  of seal  10  are designed to provide a high enough level of biasing force against their respective sealing surfaces  50 ,  54  to create a reliably fluid-tight seal, while being low enough to prevent undue friction against door panels  18 . In this embodiment, the appropriate level of biasing force can be calculated within a range of forces that both a) reliably creates a fluid-tight seal and b) results in a friction force sufficiently low to allow the user of roll-up door  16  to manually open and close roll-up door  16 . 
         [0052]    As illustrated in  FIG. 5 , when door  16  is in the closed position tip  66  extends laterally toward the middle of door panel  18  by a substantial distance, i.e., the distance between exposed surface  26  and tip  66  of lobe  40 . In the exemplary embodiment described above adapted for use with a seal receiving space  36  having width W 1  of 0.88 inches, this lateral distance may be about 1.5 inches or more. This allows seal  10  to reliably bias against outer surface  50  of door panel  18 , even if lateral edge  68  ( FIG. 5 ) of door panels  18  of door  16  are variably spaced from sidewall  62  of door frame  12 . For example, in some standard roll-up door designs, axle  70  of rollers  64  may be longer or shorter than in other standard designs, thereby changing the lateral position of edge  68  of door panels  18 . In other cases, rollers  64  (and therefore door panels  18 ) are allowed to shift laterally within roller track  56  as the roll-up door  16  opens or closes. Such lateral shifting may be significant, such as up to 0.5 inches in either lateral direction. Seal  10 , with its long sealing lobe  40 , is usable on all such standard door frame designs despite variations in the exact size and configuration, and potential lateral shift of the corresponding roll-up door. 
         [0053]    As described above, seal  10  may be installed quickly and efficiently without tools, and with little or no use of adhesives or other secondary fixation structures. Coupling body  24  is simply advanced laterally, i.e., along direction D I  ( FIG. 3 ) such that the installer standing near cargo box  22  passes seal  10  toward sidewall  62  of frame  12 . This lateral advancement is complete when coupling body  24  is fully received within seal receiving space  36 . When so installed, coupling body  24  is captured within seal receiving space  36 , as discussed in detail above, and sealing lobes  40 ,  46  protruded outwardly from seal receiving space  36 . In one exemplary embodiment, such installation may be effected without fasteners or adhesives. In another exemplary embodiment, a minimal amount of such auxiliary coupling aids is used, such as at the top or seal  12  as described above. Seal  10  is installed along its length such that the sides of door frame  12  are completely sealed. 
         [0054]    To uninstall seal  10 , seal  10  can be simply grasped (e.g., by sealing lobe  40 ) and pulled free from seal receiving space  36  and door frame  12 . Although seal  10  requires an elevated amount of force to remove from seal receiving space  36 , such force can be marshaled by a maintenance person when needed to uninstall and replace seal  10 . Such uninstallation is simplified by the minimal use (or lack of) fasteners and adhesives used in the initial installation. Thus, seal  10  may be readily replaced whenever such replacement becomes necessary. Moreover, because seal  10  can be made from a single, monolithic extruded material as detailed above, replacement seals  10  can be produced in large quantities for a minimal cost. 
         [0055]    Turning now to  FIG. 6 , a cross-sectional profile of alternative seal  110  is shown. Seal  110  is similar to seal  10  described above, with reference numerals of seal  110  analogous to corresponding reference numerals used in seal  10 , except with 100 added thereto. Structures of seal  110  correspond to similar structures denoted by corresponding reference numerals of seal  10  except as otherwise noted, and seal  110  is installed to door frame  12  in a similar fashion as described above (and as shown in  FIG. 7 ). 
         [0056]    However, coupling body  124 , main sealing lobe  140  and secondary sealing lobe  146  of seal  110  have unique geometries which provide seal  110  with unique sealing characteristics. Coupling body  124  has a narrower overall narrower profile but with longer securement ribs  134  extending therefrom. This arrangement allows for more pronounced deformation of securement ribs  134  upon assembly into seal receiving space  36  (as shown in  FIG. 7 ), and obviates the need for aperture  38  used in seal  10  ( FIG. 2 ). Also, as most clearly illustrated by a comparison of  FIGS. 5 and 7 , the overall length of seal  110  is also substantially longer than that of seal  10 . In an exemplary embodiment, the largest cross-sectional dimension of seal  110  in the undeformed state of  FIG. 6  is about 2.73 inches. The overall undeformed width W S  of coupling body  124  is about 0.71 inches, such that seal  110  is suitable for use in door frame  12  having a width W 1  of seal receiving space  36  ( FIG. 3 ) equal to 0.5 inches. 
         [0057]    Main sealing lobe  140  has a substantially reduced curvature in its at-rest, undeformed state as shown in  FIG. 6 . Accordingly, radius R 100  defined by the concave cross-sectional profile of inner surface  142  of lobe  140  is substantially larger than radius R of lobe  40  of seal  10 . As noted above, such a reduction in the curvature of lobe  140  as compared to lobe  40  produces less biasing force against outer surface  50  of door panels  18  when seal  110  is in its sealing, deformed state ( FIG. 2 ). Concomitantly, less friction is produced at the area of contact between tip  166  and outer surfaces  50  of respective door panels  18  of roll-up door  16 . For certain exemplary embodiments, such as roll-up doors commonly found on the rear enclosures of cargo trucks, the large-radius arrangement shown in  FIG. 6  has been found to provide a firm, liquid-tight seal while preventing undue friction. 
         [0058]    Main sealing lobe  140  also lacks the constant thickness T M  found in lobe  40  of seal  10  ( FIG. 2 ). Instead, lobe  140  defines a relatively constant thickness T M100  ( FIG. 6 ) between exposed surface  126  and secondary sealing lobe  146 , then a tapering thickness between secondary sealing lobe  146  and tip  166  (where tip  166  is at the end of the longitudinal extent of lobe  140 , opposite exposed surface  126  as shown in  FIG. 6 ). Stated another way, the shortest distance between concave inner surface  142  and the opposing, convex outer surface  144  of sealing lobe  140  steadily decreases as one traverses the longitudinal extent of main sealing lobe  140  from secondary sealing lobe  146  to tip  166 . 
         [0059]    Secondary sealing lobe  146  retains the generally triangular profile found in secondary sealing lobe  46  of seal  10 , but is more nearly equilateral in overall shape and has aperture  147  formed therein. As shown in  FIG. 7 , when seal  10  enters its sealing configuration with respect to door panel  18 , secondary sealing lobe  146  substantially deforms to create a liquid-tight seal with inwardly facing surface  54  of flange  52  of door frame  12 . More particularly, a first lobe wall  146 A, extending from toward tip  166  of main sealing lobe  140 , resiliently deforms into a “buckled” configuration, as shown in  FIG. 7 , when tip  148  of lobe  146  (i.e., the point on sealing lobe  146  furthest from outer surface  144  of main sealing lobe  140 ) is urged into contact with inwardly facing surface  54 . This buckling causes first lobe wall  146 A to protrude into aperture  147  as illustrated, so that tip  148  of secondary sealing lobe  146  deflects in an opposite direction to that of tip  166  of main sealing lobe  140 . 
         [0060]    The resiliency of the material of first lobe wall  146 A, i.e., the tendency of first lobe wall  146 A to return to its undeformed configuration, provides a constant biasing force urging main sealing lobe  140  toward outer surface of door panel  18 . This force biases lobe tip  166  into sealing engagement with surface  50 , in similar fashion as described above with respect to seal  10 . Meanwhile second lobe wall  146 B, which is located opposite first lobe wall  146 A and extends toward coupling body  124  as shown, is urged into sealing contact with inner surface  54  of flange  52  by the resilient deformation of main sealing lobe  140 , such that lobes  140 ,  146  bias each other into sealing engagement. In addition, the extended sealing contact of second lobe wall  146 B across a substantial portion of second lobe wall  146 B, such as about half of its cross sectional extent as illustrated, providing a reliably liquid-tight seal at surface  54 . In an exemplary embodiment, the above-described sealing action can be achieved with a lobe wall thickness TL ( FIG. 6 ) of about 0.07 inches. 
         [0061]    Turning to  FIGS. 8 and 9 , a cross-sectional profile of another alternative seal  210  is shown. Seal  210  is similar to seals  10 ,  110  described above, with reference numerals of seal  210  analogous to corresponding reference numerals used in seal  10 ,  110 , except with 100 or 200 added thereto respectively. Structures of seal  210  correspond to similar structures denoted by corresponding reference numerals of seals  10 ,  110  except as otherwise noted, and seal  210  is installed to door frame  12  in a similar fashion as described above (and as shown in  FIG. 9 ). 
         [0062]    In an exemplary embodiment, seal  220  is identical to seal  120  except at the junction between main sealing lobe  240  and coupling body  224 . More particularly, seal  220  lacks the constant-thickness section found main sealing lobe  140  (i.e., that portion of sealing lobe  140  having thickness T M100 ) and instead has a steadily increasing thickness toward coupling body  224 . As above, this thickness is measured as the shortest distance from concave inner surface  242  to convex outer surface  244 , taken along any point along the longitudinal extent of the illustrated cross-section of sealing lobe  240 . As illustrated, this arrangement eliminates any analog to exposed surfaces  26 ,  126  in seal  210 , with convex outer surface  244  of main sealing lobe  240  instead blending smoothly with side surfaces  232  of coupling body  224 . This profile enhances the strength of the connection between lobe  240  and coupling body  224 , and provides some additional biasing force to tip  266  of lobe  240 . 
         [0063]    Referring back to  FIG. 1 , bottom seal  74  and/or top seal  76  may also be provided as needed to complete liquid-tight seal around roll-up door  16 . Bottom and/or top seals  74 ,  76  may be used in a known configuration, except that the ends of bottom seal  74  may be trimmed as necessary to accommodate seals  10 ,  110  or  210  on either side of door  16 . 
         [0064]    While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.