Abstract:
A loading dock seal for around a doorway of a building includes a vertically movable side seal and a relatively fixed head seal that are adapted to seal against the rear of a truck. As the truck is loaded or unloaded of its cargo, the resulting weight change on the truck&#39;s suspension can cause the truck to raise and lower a few inches. To minimize the truck abrading the side seal, a movable coupling allows the side seal to move with the truck&#39;s vertical movement. In some embodiments, the coupling includes antifriction elements, such as rollers and bearing pads, which smoothen the motion of the side seal. Although the head seal is relatively fixed to ensure a positive seal against the face of the building, the head seal is designed to readily deform in response to the truck&#39;s vertical movement.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The subject invention generally pertains to loading dock seals and more specifically one that is vertically movable. 
   2. Description of Related Art 
   When an exterior doorway of a building is used as a loading dock for vehicles, especially trucks, the perimeter of the doorway often includes a dock seal. Dock seals close off gaps that would otherwise exist between the exterior face of the building and the back end of the truck. This allows cargo from the rear of the truck to be loaded or unloaded while dockworkers and the cargo are protected from the weather. Usually two side seals run vertically along the lateral edges of the doorway, and a top or head seal runs horizontally along the doorway&#39;s upper edge. 
   A typical dock seal comprises a resiliently compressible foam core protected by a fabric outer cover. Sealing is provided by backing the truck up against the seal, so that the seal compressively conforms to the rear shape of the truck. The foam core provides the necessary compliance and resilience to repeatedly conform to the shape of various trucks, while the outer cover protects the foam core from dirt, water and wear. 
   The greatest wear on the outer cover often occurs during the loading and unloading of a truck parked against the dock seal. Adding or removing cargo and/or driving a forklift on and off the truck bed may cause the rear of the truck to rise or lower a few inches, due to the truck&#39;s suspension. The rear of the truck rubbing tightly against the pad can tear the pad&#39;s cover or at least shorten its life significantly. 
   To address this problem, various dock seals have been developed with some success. For example, the Kinnear division of the Harsco Corporation of Columbus, Ohio has provided a compressible dock seal that moves vertically with vertical movement of the truck, thus minimizing abrasive rubbing between the two. With the Kinnear design, two side seals and the head seal are mounted to the face of a building by way of a track that allows the seals to move vertically with the truck, as the truck is being loaded or unloaded. However, since the head curtain is fixed relative to the side seals (and thus moves with the side seals), it appears that a clearance between the head seal and the building wall needs to be sealed or sheltered in some way. Otherwise, rainwater running down the wall could possibly seep behind the head seal and leak into the building. Moreover, since the head seal is between the two side seals, rather than extending over the top of them, gaps may exist between the ends of the head seal and the two side seals. To seal such gaps, and to seal the clearance between the head seal and the wall, apparently an additional cover or curtain is installed to overhang and cover the head seal and both side seals. 
   U.S. Pat. No. 4,015,380 discloses another dock seal that moves in response to vertical movement of the back of a vehicle. Here, the side seals include a corrugated sealing surface that is able to collapse and fold in the direction of the vehicle&#39;s movement. However, much of the seal&#39;s vehicle-responsive movement is provided by shifting of the sealing surface itself. Thus, it appears that much of the abrasive wear would still be concentrated at the sealing surface. 
   Other dock seals having a vertically movable head seal are disclosed in U.S. Pat. Nos. 5,775,044; 4,494,341 and 3,230,675. In each of these examples, however, the side seals appear to be fixed relative to the building wall. 
   SUMMARY OF THE INVENTION 
   In order to provide a dock seal that moves with vertical movement of a vehicle pressed against the seal, a dock seal includes a side seal and a head seal, wherein movement of the side seal is provided by a movable coupling, and movement of the head seal is provide by its ability to readily deform. 
   In some embodiments, the head seal extends out over the upper ends of the side seals with a gap therebetween to allow the side seals to move vertically. 
   In some embodiments, a fabric curtain covers the gap between the head seal and the upper ends of the side seals. 
   In some embodiments, the side seals move vertically with the vehicle to avoid damaging the seal&#39;s fabric cover, as the vehicle presses deeply into a foam core of the seal. 
   In some embodiments, the movable coupling includes a roller to reduce friction within the coupling. 
   In some embodiments, the movable coupling includes a wear pad to reduce friction within the coupling. 
   In some embodiments, the movable coupling is made of a material that is tougher or more wear resistant than the seal&#39;s fabric cover. 
   In some embodiments, the vertically movable side seal is biased towards its lower travel limit to maximize the side seals range of upward travel from its standby position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a vehicle approaching one embodiment of a dock seal in a standby mode. 
       FIG. 2  is a partial cut-away side view of the dock seal of FIG.  1 . 
       FIG. 3  is a cross-sectional view taken along line  3 — 3  of FIG.  1 . 
       FIG. 4  is a cross-sectional view taken along line  4 — 4  of FIG.  1 . 
       FIG. 5  is a cross-sectional view taken along line  5 — 5  of FIG.  1 . 
       FIG. 6  is similar to  FIG. 2 , but with a vehicle engaging the seal to place the seal in a sealing mode. 
       FIG. 7  is similar to  FIG. 6 , but showing the vehicle having risen from its position of FIG.  6 . 
       FIG. 8  is similar to  FIG. 5 , but of another embodiment. 
       FIG. 9  is similar to  FIG. 5 , but of yet another embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a vehicle  10 , such as a trailer of a truck, backing up to a loading dock  12 . Loading dock  12  is basically a doorway  14  or an opening in a wall  16  of a building, and may be associated with a dock leveler, bumpers  20 , and other items that facilitate loading and unloading of the vehicle&#39;s cargo. One such item in particular, which is the subject of this application, is a dock seal  22 . 
   When vehicle  10  is backed against dock seal  22 , seal  22  helps seal the air gap that might otherwise exist between the outer face of wall  16  and an upper  24  and lateral edges  26  of the rear of vehicle  10 . Much of the gap between the doorway and a lower rear edge  28  of vehicle  10  can be blocked off by a conventional dock leveler  18  which usually has a retractable lip  30  that can extend outward to bridge the gap. However, the gap at the upper and lateral edges of vehicle  11  typically requires additional sealing, and the shape of the gap in these areas can be quite unpredictable. Therefore, in one exemplary embodiment, dock seal  22  includes a head seal  32  (upper-sealing member) and two side seals  34  (side-sealing member), with head seal  32  sealing along upper edge  24  of vehicle  10  and side seals  34  sealing along lateral edges  6 . 
   Referring to  FIGS. 2-5 , side seal  34  includes a core  36  that provides the desired properties of resilience and compressibility. Compressibility allows seal  34  to conform to the contour of the vehicle&#39;s back surface to effectively seal against outside air, and resilience allows seal  34  to substantially recover its original decompressed shape. In one embodiment, core  36  consists of a resilient, compressible foamed polyurethane or foamed polyester, such as, for example, an L24 open-cell polyurethane foam provided by Leggett &amp; Platt of Carthage, Mo. However, it should be appreciated by those skilled in the art that a wide variety of other synthetic or natural foams may also work well. Moreover, mechanical springs or bellows may also accomplish the desired functions otherwise provided by foam. 
   Since the inherent porosity of foam tends to absorb moisture, hold dirt, and make core  36  less wear resistant, a tough, flexible, water-resistant protective cover  38  covers the most exposed areas of core  36 . One example such a cover would be a 3022_MFRLPC_DC7 material provided by the Seaman Corporation of Wooster, Ohio. Other examples of cover materials would include, but not be limited to, HYPALON, canvas duck, rubber impregnated fabric and coated nylon fabric. For some embodiments, cover  38  wraps around core  36 , and self-tapping screws  40  fasten cover  38  to side flanges  42  of a backer  44  made of sheet metal or some other appropriate material. Although screws  40  are used in a preferred embodiment, cover  38  can be held in place using any appropriate fastener or means for attaching, such as hooks, screws that are not self-tapping, adhesive, touch-and-hold fastener (e.g., VELCRO), sewing, snaps, etc. 
   To minimize abrasion between cover  38  and the rear of vehicle  10 , a movable coupling  46  attaches side seal  34  to wall  16 , so that side seal  34  can move vertically with vehicle  10 , as vehicle  10  is being loaded or unloaded of its cargo. Such a coupling can be provided by a variety of structures of which coupling  46  represents a currently preferred embodiment. In this example, coupling  46  includes a shoulder screw  48  that attaches backer  44  to a base plate  50 , which in turn is fastened to wall  16  by way of anchor screws  52 . Screws  48  extend through vertically elongated slots  54  in side flanges  56  of base plate  50  and screw into side flanges  58  of backer  44 . In this case, each screw  40  actually screws into a rivet-nut  60 , which is an internally threaded fastener that is pressed into flanges  58 . A sliding fit between screws  48  and slots  54  allows backer  44  to move a few inches vertically relative to base plate  50 . Thus, cover  38  and foam core  36  can also move a few inches vertically, as backer  44  carries these items. Although backer  44 , screws  48  and base plate  50  are each made of metal, making one or more of these items of a different material is well within the scope of the invention. 
   To smoothen the sliding action between backer  44  and base plate  50 , several things can be done. For example, an anti-friction wear pad, such as a wear strip  62  can be placed between backer  44  and base plate  50 . Wear strip  62  can be made of UHMW (ultra high molecular weight polyethylene) or some other low friction, wear resistant material that is distinguishable from the material of backer  44  and/or base plate  50 . In some cases, strip  62  can be adhesively attached to backer  44 . To avoid friction and wear between flanges  56  and the adjacent portion of cover  38 , the heads of screws  40  provide a standoff that help keep flanges  56  and cover  38  from rubbing against each other. Also, a washer  64  installed around screws  48  and situated between flanges  56  and  58  helps keep cover  38  and flanges  56  separated. 
   To seal along upper edge  24  of vehicle  10 , head seal  32  runs horizontally above doorway  14  and extends over upper ends  66  of side seals  34 . Similar to side seals  34 , head seal  32  includes a resiliently compressible foam core  36 ′ protected by a cover  38 ′ that is held to a backer  70  by screws  68 . Backer  70  is mounted to wall  16  just a few inches above ends  66  to provide a gap  72  that allows side seals  34  some vertical movement. A fabric cover  74 , attached to head seal  32  and extending below the upper ends  66  of side seals  34 , helps cover gap  72 . 
   In operation, vehicle  10  begins backing toward dock seal  22 , which is in a standby mode, as shown in  FIGS. 1-3 . In the standby mode, vehicle  10  has not yet engaged dock seal  22 , and side seals  34  are at their lower limit of travel. In this case, the lower limit is determined by backer  44  resting atop an angle  76  that is fixed relative to base plate  50 . However, it should be appreciated by those skilled in the art that a wide variety of other stops could be used to limit the lower travel of side seals  34 . For example, screw  48  reaching the lower end of slot  54  could also determine the lower limit of travel for side seals  34 . 
   As vehicle  10  presses into side seals  34  and head seal  32 , dock seal  22  compresses into its sealing mode (i.e., engaging vehicle  10 ), as shown in FIG.  6 . Subsequent upper movement  78  of vehicle  10  can raise side seals  34  and distort head seal  32 , while dock seal  22  remains in its sealing mode. In  FIG. 7 , side seals  34  are shown to have risen about halfway between their lower limit of FIG.  6  and an upper limit. The upper travel limit of side seals  34  can be provided in a number of ways including, but not limited to, screws  48  reaching the end of their upper travel within slots  50 , or upper end  66  of side seals  34  abutting the underside of head seal  32 . 
   Having backer  70  of head seal  32  fixed relative to wall  16  simplifies the design of dock seal  22  by reducing the number of moving parts that might otherwise be required. Moreover, such a design can make it easier to seal the area between backer  70  and the face of wall  16 , as the sealed area does not have to allow for any sliding motion between backer  70  and wall  16 . Nonetheless, the distortion of head seal  32  accommodates ample movement of vehicle  10  without excessive force, because cover  38 ′ can readily bend along various horizontal axes (e.g., lines  80  and  82 ) upon moving from its position of  FIG. 6  to that of FIG.  7 . The distortional movement of the cross-section shape of cover  38 ′ as viewed in  FIG. 6  is comparable to the freedom of movement found in a typical four-bar linkage. In contrast, the shape of cover  38  on side seals  34  provides large generally planar surfaces  39  (e.g., the surface of cover  38  that is viewable in  FIG. 2 ) that resist vertical deflection of a sealing face  41  of side seal  34  relative to backer  44 . Thus, firmly affixing head seal  32  to wall  16  while providing side seals  34  with a movable coupling  46  provides a dock seal  22  with desirable sealing and wear resistant features. 
   In another embodiment, shown in  FIG. 8 , a side seal  84  includes a movable coupling  86  with a roller  88  for reducing friction. Roller  88  represents any rolling element including, but not limited to solid round rods, balls, and cylinders. A base plate  50 , is the same as the one used for side seals  34 ; however, seal  84  has an inverted backer  90  with flanges  92  that are pinned to flanges  56  by way of rod  94 . In some embodiments, rod  94  feeds through the center of roller  88  (having a tubular shape), to maintain roller  88  in rolling contact with backer  90  and base plate  50 . Washers  96  and a conventional fastener  98  (e.g., E-clips, C-clips, cotter pins, nuts, etc.) can be used to help hold rod  94  within slots  54  of flanges  56  and the holes of flanges  92 . 
   In yet another embodiment, shown in  FIG. 9 , a side seal  100  provides a movable coupling  102  by having a backer  104  with flanges  106  that are captured within flanges  108  of a base plate  110 . A sliding fit between flanges  106  and  108  allows side seal  100  to move vertically with vehicle  10 . To reduce sliding friction, antifriction element  62  can be inserted between flanges  106  and base plate  110 . 
   Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those skilled in the art. Therefore, the scope of the invention is to be determined by reference to the claims, which follow.