Abstract:
In order to provide a loading dock shelter with an effective seal, the shelter is provided with a side curtain that is semi-rigid. The relative stiffness of the curtain allows it to be supported along a vertical edge, while a distal vertical edge of the curtain can be cantilevered for sealing against the side of a truck. The curtain has sufficient flexibility and resilience to at least partially seal against the truck without having to rely on compressible foam. In some cases, the semi-rigid curtain is attached to a side frame by way of a sliding connection that allows for differences in thermal expansion between the curtain and the frame. A relatively pliable corner seal helps seal a gap between the side curtain and an adjacent head curtain.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The subject invention generally pertains to loading dock shelters and more specifically to an enhanced sealing member for such a shelter.  
           [0003]    2. Description of Related Art  
           [0004]    Trucks and other vehicles typically back up against a loading dock or doorway of a building to facilitate loading and unloading of the vehicle&#39;s cargo. Often a dock shelter is installed around the doorway to help shelter the area between the perimeter of the doorway and the rear of the vehicle. If left unsheltered, air gaps between the outer wall of the building and the back of the vehicle might allow the outside weather to increase the building&#39;s heating or cooling load, allow rain and snow to enter the interior of the building, or simply subject the inside dock workers to an uncomfortable draft while they service the vehicle.  
           [0005]    Dock shelters usually include a framework that extends one to three feet outward from the face of the building wall. In some cases, pliable curtains hang from the framework and are situated to drape over the top and either side of a vehicle parked under the shelter. Such curtains are generally not self-supporting and tend to be rather limp, which can create a poor appearance. Lateral reinforcement of such curtains may be provided by including stays or other stiffeners. While this may improve appearance and/or sealing characteristics, it also requires additional components and labor to assemble. Further, while shelters may be adequate in milder climates, additional or alternate sealing may be required where weather conditions are more severe.  
           [0006]    Thus, some loading docks are provided with dock seals made of a resiliently compressible foam pad. As a truck backs into the dock and against the seal, the foam pad compresses to conform to the contour of the rear edges of the truck. Although effective, such seals can be expensive, as they comprise an assembly of components. The foam pad usually needs a tough outer cover to protect the pad from wear and to prevent the pad from absorbing water and dirt. A cover should be tough to resist wear, yet pliable to allow the foam pad to compress. Unfortunately, some of the toughest materials are not very pliable, and vise versa. So, a compromise is often needed in selecting a cover with an optimum combination of toughness and pliability.  
           [0007]    Consequently, a need exists for a dock shelter that provides a more positive seal than current shelters, yet is more economical than conventional dock seals.  
         SUMMARY OF THE INVENTION  
         [0008]    In order to provide a dock shelter with a more effective seal, a dock shelter is provided with a side curtain that is semi-rigid. The relative stiffness of the curtain allows it to be supported along a vertical edge, while a distal vertical edge of the curtain can be cantilevered for sealing against the side of a truck. The curtain has sufficient flexibility and resilience to at least partially seal against the side of a truck without having to rely on compressible foam. In some cases, the semi-rigid curtain is attached to a side frame by way of a sliding connection that allows for differences in thermal expansion between the curtain and the frame.  
           [0009]    In some embodiments, a dock shelter is provided with a head curtain attached to a head frame by way of a sliding connection that allows for differences in thermal expansion between the head frame and the head curtain.  
           [0010]    In some embodiments, a corner curtain covers the gap between a side curtain and a head curtain with the corner curtain being more pliable than the side curtain or the head curtain.  
           [0011]    In some embodiments, a sliding connection between a side curtain and a side frame is created by providing the curtain with vertical slots used for anchoring the curtain to the frame.  
           [0012]    In some embodiments, the dock shelter includes a vertically elongated side curtain of sufficient rigidity to be cantilevered from an anchored vertical edge out to a distal vertical edge.  
           [0013]    In some embodiments, the distal vertical edge of a side curtain is curved about a vertical axis to help prevent the edge from catching on a vehicle as the vehicle leaves the dock shelter.  
           [0014]    In some embodiments, metal stays provide a plastic side curtain with greater rigidity and resilience. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a front view of one embodiment of a dock shelter with a semi-rigid side curtain.  
         [0016]    [0016]FIG. 2 is a side view of the dock shelter of FIG. 1 showing a vehicle backing into the shelter.  
         [0017]    [0017]FIG. 3 is the same as FIG. 2, but showing the vehicle having already backed into the shelter.  
         [0018]    [0018]FIG. 4 is a cross-sectional view taken along line  4 - 4  of FIG. 3.  
         [0019]    [0019]FIG. 5 is a cross-sectional view taken along line  5 - 5  of FIG. 3.  
         [0020]    [0020]FIG. 6 is a cross-sectional view taken along line  6 - 6  of FIG. 1.  
         [0021]    [0021]FIG. 7 is a cross-sectional view taken along line  7 - 7  of FIG. 6.  
         [0022]    [0022]FIG. 8 is a cross-sectional view similar to FIG. 6, but of another embodiment.  
         [0023]    [0023]FIG. 9 is a cross-sectional view similar to FIG. 6, but of another embodiment.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    Referring to FIGS.  1 - 3 , a dock shelter  10  installed around a doorway  12  of a loading dock  14  includes semi-rigid side curtains  16  and  18  that help provide a weather seal between the rear sides of a vehicle  20  and a wall  22  of a building. To help seal along a rear upper surface of vehicle  20 , a head curtain  24  (similar to side curtains  16  and  18  or of another design) can be installed along an upper portion of dock shelter  10 .  
         [0025]    To support the curtains, shelter  10  includes a frame  26  comprising a head frame  28 , a right side frame  30  and a left side frame  32  that respectively support curtains  16 ,  18  and  24 . Frame  26  attaches to wall  22  and supports the curtains in an offset relationship to the face of wall  22 . The offset relationship allows vehicle  20  to back into shelter  10  and underneath head frame  28 . As vehicle  20  backs into shelter  10  and against bumpers  30  (i.e., moves from the position of FIGS. 2 and 4 to that of FIGS. 3 and 5), the sides and top of vehicle  20 , being larger than the inner dimensions of shelter  10 , deflect the inner edges of curtains  16 ,  18  and  24  backward and inward. The inner edges of the curtains thus provide a sliding seal against the rear sides and roof of vehicle  20 .  
         [0026]    To create the sliding seal, curtains  16 ,  18  and  24  can be moved from their standby positions of FIGS. 1, 2 and  4  to their operative sealing positions of FIGS. 3 and 5, as vehicle  20  backs into shelter  10 . Although such curtain movement can be provided by using hinges to attach the curtains to frame  26 , a preferred approach is to make curtains  16 ,  18  and  24  of a material having sufficient flexibility to resiliently bend without the use of hinges. However, the curtain material preferably still has sufficient rigidity to allow left side curtain  16  to be cantilevered from a proximal edge  36  (attached to side frame  32 ) to a distal edge  38  (adapted to slidingly engage vehicle  20 ). The same applies to right side curtain  18 . Head curtain  24 , as mentioned earlier, can be of a similar construction or of another design entirely. For the sake of simplicity, dock shelter  10  will be described primarily with reference to left side curtain  16 , with right side curtain  18  and head curtain  24  having similar features.  
         [0027]    In some embodiments, side curtain  16  is made of ⅛-inch thick high molecular weight polyethylene. Although other materials and thickness can be used, this material in particular provides several benefits. The relatively high density and other properties of high molecular weight polyethylene makes it more resistant to water, dirt and abrasion than many foam materials, and thus the material does not require a protective cover. The rigidity of polyethylene not only provides a neat, sag-free appearance, but also allows side curtain  16  to be cantilevered from proximal edge  36 , rather than being suspended from its top edge. Supporting curtain  16  from the side allows distal edge  38  more freedom of movement, especially near the top of curtain  16 , thus distal edge  38  can effectively seal against vehicle  20  over a broader range of curtain deflection.  
         [0028]    A curtain made of polyethylene alone may have sufficient resilience to return from its operative position to its standby position, especially if gravity urges the curtain to its standby position, as is the case with head curtain  24 . Nonetheless, side curtain  16  may include several spring-steel stays  40  that improve the curtain&#39;s overall resilience. Stays  40  can be attached to side curtain  16  by any one of a variety of fasteners  42  including, but not limited to, screws or rivets. Fasteners  42  are preferably attached at opposite ends of each stay  40  to allow a central portion of stay  40  to bend away from the plastic portion of curtain  16  as curtain  16  deflects about a vertical axis  44  (FIG. 5).  
         [0029]    To smoothed the movement of side curtain  16  as a departing vehicle allows curtain  16  to return to its standby position, distal edge  38  is curved about a vertical axis  46 , as shown in FIG. 4. With distal edge  38  being curved rather than sharp and straight, distal edge  38  is less likely to catch on the side of vehicle  20  as vehicle  20  moves out from within dock shelter  10 .  
         [0030]    In some cases, side frame  32  and side curtain  16  have different coefficients of thermal expansion. For instance, curtain  16  being made of polyethylene has a greater coefficient of thermal expansion than a side frame being made of wood. To accommodate this difference, a sliding connection  48  can be used to attach side curtain  16  to side frame  32 , as shown in FIGS. 1, 6 and  7 . For example, sliding connection  48  can be provided by screws  50  protruding through elongated slots  52  in curtain  16  and screwing into side frame  32 . The shank of screws  50  form vertically fixed posts which extend into the elongated slots  52 . One will appreciate that other vertically fixed posts could achieve the same function—such as posts formed in the side frame or otherwise affixed thereto. In the case of screws  50 , they serve the additional advantageous function of limiting movement of the curtain away from the wall due to the presence of the screw heads. A stand-off bushing  54  can be added to help prevent the head of screw  50  from being over tightened against curtain  16 . If bushing  54  is used, the shank of screw  50  fits through bushing  54 , and the bushing is a part of the vertically fixed post as a sliding fit is provided between an outer diameter of bushing  54  and the width of slot  52 . For the illustrated dock shelter, side curtain  16  includes one point of attachment  56  that is relatively fixed, rather than being a sliding connection. The fixed point ensures that any expansion of side curtain  16  will be from that point. In other words, with point  56  being near the top of side curtain  16 , the bottom of curtain  16  will move more than the top, as curtain  16  expands and contracts vertically. Alternatively, the curtain adjacent point  56  could have a slot as well, but having a smaller vertical extent than the other slots and positioned such that the screw or vertically fixed post would normally be disposed at the top of that slot.  
         [0031]    [0031]FIG. 8 illustrates another example of a sliding connection  48 ′. Here, a sliding fit exists between slot  52  and screw  50 ; however, an angle member  58  attached to a side frame  32 ′ prevents the head of screw  50  from being tightened against curtain  16 . Thus, bushing  54  can be eliminated.  
         [0032]    In another example of a sliding connection  48 ″, shown in FIG. 9, a side curtain  16 ′ includes a ridge  60  running along a proximal edge  36 ′ of curtain  16 ′. An angle member  62  with an added lip  64  then captures ridge  60  to limit the curtain&#39;s sideways movement (i.e., perpendicular to the length of proximal edge  36 ′). Thus, ridge  60  and angle member  62  inhibit curtain  16  from completely separating from a side frame  32 ″ and member  62 . However, angle member  62  provides ridge  60  with enough clearance to allow some sliding movement between curtain  16 ′ and frame  32 ″ for thermal expansion in a direction parallel to ridge  60 . Ridge  60  can be an integral extension of curtain  16 ′ or can be an added piece attached using an adhesive or a mechanical fastener. A mechanical stop, such as a fastener or some other obstruction, may be added to limit how far ridge  60  can slide within angle member  62 .  
         [0033]    To help cover a gap  64  between side curtain  16  and head curtain  24 , a corner curtain  66  can be installed at each upper corner of dock shelter  10 . Comer curtain  66  can be especially useful, as gap  64  increases in size as the other curtains deflect from their standby positions to their operative positions. As gap  64  widens, its shape changes significantly with its defining edges being distorted three-dimensionally. To maintain gap  64  covered under such distortion, corner seal  66  overlaps both head curtain  24  and side curtain  16 . Also, corner curtain  66  is preferably more pliable than curtains  16  and  24  to effectively conform to the changing shape of gap  64 . In some embodiments, corner curtain  66  is a relatively lightweight vinyl attached to frame  26 , such that corner curtain  66  is in front of side curtain  16  and behind head curtain  24 , or conversely, in front of head curtain  24  and behind side curtain  16 .  
         [0034]    Although the invention is described with reference to a presently preferred embodiment, it should be appreciated by those skilled in the art that various modifications are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the claims that follow.