Abstract:
Head curtains for dock shelters or dock seals are disclosed. An example head curtain assembly for a vehicle loading dock includes a retractable curtain stiffened by a resiliently compressible foam panel that is more flexible about a horizontal axis than about a vertical axis. The difference in directional flexibility can be created by sewing the foam panel to a pliable cover using a series of parallel horizontal thread lines. The thread lines create in the foam a series of compressed indentations that run horizontally across the curtain so that the curtain tends to bend more easily along those lines. The relative stiffness in the horizontal direction enables the curtain to exert an appreciable sealing force against two lateral dock seal members, and the vertical flexibility makes the curtain easy to retract to accommodate vehicles of various heights. Touch-and-hold fasteners make many of the individual components of the head curtain readily replaceable.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The subject disclosure generally pertains to loading dock shelters and dock seal systems, and more specifically, to head curtains for such systems. 
       BACKGROUND 
       [0002]    Trucks having open rear cargo bays are typically backed into alignment with a loading dock or other doorway of a building to facilitate loading and unloading of the vehicle. A significant gap is usually created between the rear of the truck and the face of the building, which exposes the interiors of the building and the truck to the outside environment during loading and unloading. Such gaps can be at least partially sealed by installing either a loading dock shelter or a loading dock seal around the perimeter of the doorway. 
         [0003]    To seal or shelter the vehicle&#39;s rear vertical edges, dock shelters and dock seals usually have some type of lateral weather barrier installed along the side edges of the doorway. For dock shelters, the weather barrier usually shelters or seals against the vertical sides of the vehicle&#39;s trailer. An example of such an approach is shown in U.S. Pat. No. 3,322,132. Dock seals, on the other hand, usually have lateral weather barriers that are resiliently compressible for conformingly sealing against the vertical rear edges of the vehicle. An example of such an approach is shown in U.S. Pat. No. 5,125,196. Regardless of the structural design of the lateral weather barrier, the upper rear edge of the vehicle is often sealed or sheltered by a head curtain that drapes down onto the top of the vehicle as the vehicle backs into the dock. 
         [0004]    If the head curtain is extra long to accommodate a broad range of vehicle heights, the dock shelter or dock seal might include means for vertically retracting the curtain so that the curtain length is appropriate for the height of the particular vehicle at the dock. Thus, the curtain needs to be flexible not only for deflecting in reaction to the vehicle backing into the dock, but also for enabling the curtain to be retracted. Such flexibility or compliance, however, can weaken or hinder the curtain&#39;s ability to forcibly seal against the rear upper edge of the vehicle. Thus, instead of the curtain applying sealingly tight pressure against the upper edge of the vehicle, a pliable curtain readily deflects backwards toward the doorway of the dock. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a perspective view of an example dock apparatus described herein. 
           [0006]      FIG. 2  is an exploded perspective view of the example dock apparatus of  FIG. 1 . 
           [0007]      FIG. 3  is a cross-sectional view of the example dock apparatus of  FIG. 1  taken along line  3 - 3  of  FIG. 1 . 
           [0008]      FIG. 4  is a cross-sectional view similar to  FIG. 3  but showing a vehicle engaging the dock apparatus of  FIGS. 1 ,  2 , and  3 . 
           [0009]      FIG. 5  is a cross-sectional view of the example dock apparatus of  FIG. 1  taken along line  5 - 5  of  FIG. 1 . 
           [0010]      FIG. 6  is a cross-sectional view similar to  FIG. 5  but showing a head curtain assembly of the dock apparatus of  FIGS. 1-5  in a retracted position. 
           [0011]      FIG. 7  is a cross-sectional view similar to  FIG. 5  but showing another example dock apparatus described herein. 
           [0012]      FIG. 8  is a cross-sectional view of the example dock apparatus of  FIG. 7  with a vehicle engaging the example dock apparatus. 
           [0013]      FIG. 9  is a cross-sectional view similar to  FIG. 8  but showing a head curtain assembly of the example dock apparatus of  FIGS. 7 and 8  in a retracted position. 
           [0014]      FIG. 10  is a cross-section view similar to  FIG. 3  but showing another example dock apparatus described herein. 
           [0015]      FIG. 11  is a cross-section view similar to  FIG. 10  but showing a vehicle engaging the example dock apparatus of  FIG. 10 . 
           [0016]      FIG. 12  is a cross-sectional view similar to  FIG. 10  but showing another example dock apparatus described herein. 
           [0017]      FIG. 13  is a cross-sectional view of the example of  FIG. 12  but showing a vehicle engaging the example dock apparatus of  FIG. 12 . 
           [0018]      FIG. 14  is a cross-sectional view similar to  FIG. 10  but showing yet another example dock apparatus described herein. 
           [0019]      FIG. 15  is a cross-sectional view of the example of  FIG. 14  but showing a vehicle engaging the example dock apparatus of  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIGS. 1-6  show a loading dock apparatus  10  that helps seal and/or shelter the rear access opening of a truck/trailer vehicle  12  at a loading dock  14 . Dock  14  includes a doorway  16  in a wall  18  of a building. The dock apparatus  10  provides a barrier to weather and other elements as the vehicle&#39;s cargo is being loaded or unloaded at the doorway. To accommodate vehicles of various heights, dock apparatus  10  includes a head curtain assembly  20  with a retractable curtain  22  that seals along the vehicle&#39;s upper rear edge. 
         [0021]    To seal or shelter the vehicle&#39;s rear side edges, an upper sealing assembly illustratively in the form of a head curtain assembly  20  could be used with a dock shelter that includes lateral weather barriers or side panels that are relatively rigid and incompressible. Head curtain assembly  20 , however, is particularly suited for a dock seal  24  having lateral weather barriers in the form of resiliently compressible side pads  26 , thus assembly  20  will be described and illustrated with reference to dock seal  24 . 
         [0022]    Lateral edges  28  of curtain  22  preferably seal against the inner surfaces of side pads  26  (as shown in  FIG. 3 ) and/or seal against an inner surface  30  of a pair of flexible boots  32  that protect the upper ends of side pads  26 . A touch-and-hold fastener  27  (e.g., a fabric hook-and-loop fastener such as VELCRO™) can help seal edges  28  to surface  30 . As an alternative to conventional windstraps, an inner flexible panel  29  on boot  32  is coupled to wall  18  to help prevent vehicle  12  from pulling curtain assembly  20  away from wall  18  as vehicle  12  departs dock  14 . The connection  27  between edges  28  and surface  30  also helps prevent curtain assembly  20  from uncontrolled movement in strong winds when not engaged by a vehicle. To minimize wear, side pads  26  may include one or more cavities  31  ( FIG. 2 ) that reduce the compressive forces in certain localized areas, such as in the area behind boots  32 . 
         [0023]    When side pads  26  are compressed by the rear end of vehicle  12 , as shown in  FIG. 4 , pads  26  tend to bulge and push inward against the lateral edges  28 . To maintain a positive seal at edges  28 , a resiliently compressible foam panel  34  (covered by item  38 ) may be included to increase the rigidity or stiffness (e.g., horizontal rigidity) to curtain  22 . In addition to improved sealing at edges  28 , the curtain&#39;s increased horizontal stiffness in conjunction with pads  26  bulging inward firmly retains curtain  22  between pads  26 , and the bulging sections forcibly hold curtain  22  sealingly tight against the rear upper edge of vehicle  12 . 
         [0024]    To ensure that the horizontal stiffness does not hinder the curtain&#39;s ability to retract vertically from the position of  FIG. 5  to that of  FIG. 6 , foam panel  34  includes a series of compressed indentations  36  or bending creases that render panel  34  more flexible about a horizontal axis than about a vertical axis. Indentations  36  can be created or formed by sewing panel  34  to a pliable cover  38 , in which the sewing process produces a plurality of stitches  40  that holds the indentations in compression. Other methods of producing compressed indentations  36  include, but are not limited to, localized ultrasonic or heat sealing of cover  38  to foam panel  34  or localized ultrasonic or heat sealing of foam panel  34  to itself. Regardless of how indentations  36  are formed, maintaining foam panel  34  as a unitary piece, as opposed to a plurality of segments, simplifies manufacturability and provides a neat, clean appearance. 
         [0025]    The assembly of dock apparatus  10  is perhaps best understood with reference to  FIGS. 2 and 5 . Side pads  26  can be attached to wall  18  using any suitable means including, but not limited to, methods that are well known to those of ordinary skill in the art. To support foam panel  34 , curtain  22 , and an upper sheet  42  extending from curtain  22 , the head curtain assembly  20  of the illustrated example includes a resiliently crushable support panel  44  atop side pads  26 . In some examples, support panel  44  comprises a semi-rigid polymeric sheet  46  (e.g., polyethylene, polypropylene, fiberglass, etc.) encased within a pliable cover  48 . The semi-rigidity panel  44  makes it more impactable and durable than other conventional frameworks that are substantially rigid and readily damaged by vehicular impact. Panel  44  may be designed so that it could be impacted by a vehicle and compressed all the way to the loading dock wall without damage—a function not found in a conventional rigid frame. 
         [0026]    A touch-and-hold fastener  50  (e.g., a fabric hook-and-loop fastener such as VELCRO™) can be used to contain sheet  46  within cover  48 . A resiliently flexible horizontal elongate polymeric stay  52  (e.g., rod, bar, tube, etc. made of polyethylene, polypropylene, fiberglass, etc.) can be attached to panel  44  to provide support panel  44  with additional stiffness. Stay  52  can be held within a sleeve illustratively depicted as a loop of material  54  so that stay  52  can be readily replaced if necessary. A tube  56  or bar anchored to wall  18  via a series of fasteners  58  can be used for attaching an upper flange of support panel  44  to wall  18 . 
         [0027]    To provide head curtain assembly  20  with various components that can be readily replaced individually, touch-and-hold fasteners can be used throughout the assembly. A touch-and-hold fastener  60 , for example, can attach an upper end of the creased foam panel&#39;s cover  38  to upper sheet  42 , and another touch-and-hold fastener  62  can connect the lower end of cover  38  to a lip  64  extending from curtain  22 , thereby removably attaching foam panel  34  to curtain  22 . An additional touch-and-hold fastener  66  can removably attach cover  38  to support panel  44 . Other touch-and-hold fasteners  68  and/or  70  can fasten upper sheet  42  to support panel  44  and/or to a flap  72  anchored to wall  18 . Flexible boots  32  that help protect the upper ends of side pads  26  can also be removably attached using a touch-and-hold fastener  74  so that boots  32  are readily replaceable. 
         [0028]    A resiliently flexible horizontal polymeric stay  76  (e.g., rod, bar, tube, etc. made of polyethylene, polypropylene, fiberglass, etc.) can be attached to the lower end of curtain  22  to provide curtain  22  with additional horizontal stiffness. Stay  76  can be held within a loop of material  78  so that stay  76  can be readily replaced if necessary. Stay  76  with or without additional weight can also help hold curtain  22  taut (e.g., vertically taut) so that curtain  22  can lie relatively flat when fully extended, as shown in  FIG. 5 . 
         [0029]    To raise curtain  22  from its position of  FIG. 5  to that of  FIG. 6 , a pull cord  80  (i.e., any pliable elongate member, such as a rope, strap, chain, etc.) attached to a lower end of curtain  22  can be threaded through a series of pulleys or eyelets  82  with one end  84  of cord  80  available for an operator (e.g., a manual operator or a mechanical operator)) to pull cord  80  so as to raise curtain  22 . If cord  80  is manually pulled, curtain  22  can be held at a raised position by temporarily securing cord  80  to a cleat  86  anchored to wall  18 , as shown in  FIG. 6 . 
         [0030]    In another example,  FIGS. 7 ,  8  and  9  illustrate another example dock apparatus  88  having a head curtain assembly  90 . In this example, dock apparatus  88  comprises a front curtain  92  suspended between two lateral weather barriers  26 . To accommodate vehicles of various heights, a pliable elongate member  94  (e.g., a pull cord, rope, strap, chain, etc.) is coupled to a distal end  96  of front curtain  92  to selectively position distal end  96  between a lowered position ( FIG. 7 ) and a raised position ( FIG. 9 ). To adjust the height of curtain  92 , elongate member  94  can be actuated by a motorized hoist  98  or manually pulled and released. 
         [0031]    To ensure that front curtain  92  seals firmly against the rear of vehicle  12 , a stiffener  100  is installed behind front curtain  92 . Stiffener  100  is less flexible than front curtain  92  and is a horizontally elongate member that extends between the two lateral weather barriers  26  such that stiffener  100  becomes compressed horizontally between the two lateral weather barriers  26  as the lateral weather barriers are compressed by vehicle  12 . Although the actual structure of stiffener  100  may vary, in some cases, stiffener  100  comprises a resilient foam cylinder  102  reinforced by a plastic tube  104 . For additional stiffness, a resiliently flexible rod  106  can be attached to distal end  96  of front curtain  92 . 
         [0032]    In some examples, curtain assembly  90  includes a rear curtain  108  that helps contain and protect stiffener  100  and a lower section of elongate member  94 . The lower end of rear curtain  108  connects to distal end  96  of front curtain  92 . An upper end  110  of rear curtain  108  connects to the back side of front curtain  92  with one or more openings  112  for feeding elongate member  94  from the interior space between curtains  92  and  108  and externally mounted hoist  98  or cleat  86  ( FIG. 5 ). 
         [0033]    To help prevent stiffener  100  from escaping between curtains  92  and  108 , a pliable retention member  114  may be used to attach stiffener  100  to an upper or lower end of curtain  92  and/or curtain  108 . In some cases, retention member  114  is a sheet of pliable material that extends about the full length of stiffener  100 . 
         [0034]    Operation of dock apparatus  88  could begin with apparatus  88  in the lowered position, as shown in  FIG. 7 . Vehicle  12  backs into the dock and compresses the two lateral weather barriers  26 , as shown in  FIG. 8 . In this position, lateral weather barriers  26  bulge inward toward each other (similar to  FIG. 4 ), thereby holding stiffener  100  firmly up against the rear of vehicle  12 . To prevent front curtain  92  from obstructing the rear access opening of vehicle  12 , pliable elongate member  94  can be shorted to pull distal end  96  upward to the raised position of  FIG. 9 . As pliable elongate member  94  lifts distal end  96 , front curtain  92  cradles and lifts stiffener  100 , and rear curtain  108  folds over onto itself. 
         [0035]    Once in the configuration of  FIG. 9 , bulging sections of lateral weather barriers  26  pressing stiffener  100  up against vehicle  12  holds curtain assembly  90  in the raised position, perhaps even if elongate member  100  is released (e.g., disengaged from a cleat or released by winch  98 ). However, when vehicle  12  departs while elongate member  94  is slack, curtain assembly  90  can freely and automatically fall back to the lowered position of  FIG. 7 . 
         [0036]    If hoist  98  is used for raising curtain assembly  90  (as opposed to the manual option of  FIGS. 5 and 6 ), the electrical current drawn by the hoist  98  can be sensed and used as a means for automatically stopping the lift of curtain  92 . Lifting stiffener  100  from the lowered position of  FIG. 8  to the raised position of  FIG. 9  generally requires less current than it takes to lift stiffener  100  up and over the upper rear edge of vehicle  12 , i.e., above and beyond the stiffener&#39;s position of  FIG. 9 . Such increase in current drawn by the hoist  98  could be used as a signal for stopping hoist  98  when stiffener  100  reaches its properly raised position. The operation of hoist  98  could also be controlled in concert with other dock-related equipment including, but not limited to, vehicle restraints, dock levelers, doors, vehicle sensors, etc. 
         [0037]    To enhance a lateral weather barrier&#39;s ability to firmly hold a head curtain (e.g., including, but not limited to curtain or curtain assemblies  20 ,  90  or  120 ) up against the rear of vehicle  12 , a lateral weather barrier can be provided with a flexible inner surface that is shaped such that the surface bulges in a particularly advantageous manner. Examples of such surfaces are illustrated in  FIGS. 10-15 . The surfaces in these examples are part of a boot, wherein the boot is considered as being part of a lateral weather barrier (i.e., the lateral weather barrier includes the boot). Such functionality was not possible in previous systems that did not have adequate lateral stiffness to be held in place by the inwardly-bulging lateral weather barriers  26 . 
         [0038]    In  FIGS. 10 and 11 , two inner surfaces  116  of the boots of lateral weather barriers  118  allow some lateral clearance or light interference with curtain  120  when vehicle  12  is spaced apart from weather barriers  118 , as shown in  FIG. 10 . Under compression by vehicle  12 , however, surfaces  116  bulge toward each other to hold curtain  120  firmly against vehicle  12 , as shown in  FIG. 11 . Surfaces  116  can be provided by a resiliently flexible panel similar to panel  29  of  FIG. 2 . 
         [0039]    In  FIGS. 12 and 13 , two inner surfaces  122  of the boots of lateral weather barriers  118  allow some lateral clearance or light interference with curtain  120  when vehicle  12  is spaced apart from weather barriers  118 , as shown in  FIG. 12 . Under compression by vehicle  12 , however, surfaces  122  bulge toward each other to hold curtain  120  firmly against vehicle  12 , as shown in  FIG. 13 . Surfaces  122  can be provided by a resiliently flexible panel sewn or otherwise attached to a panel similar to panel  29  of  FIG. 2 . 
         [0040]    In  FIGS. 14 and 15 , two inner surfaces  124  of the boots of lateral weather barriers  118  allow some lateral clearance or light interference with curtain  120  when vehicle  12  is spaced apart from weather barriers  118 , as shown in  FIG. 14 . Under compression by vehicle  12 , however, surfaces  124  bulge toward each other to hold curtain  120  firmly against vehicle  12 , as shown in  FIG. 15 . Surfaces  124  can be provided by a resiliently flexible panel sewn or otherwise attached to a panel similar to panel  29  of  FIG. 2 . 
         [0041]    It should be noted that existing dock seals with a compressible foam head pad can be retrofitted with the head curtain assemblies disclosed herein. In replacing an existing head pad, however, it may be beneficial to add a short vertical extension onto the existing side pads so that the new head curtain assembly is at sufficient height properly service vehicles of varying heights. Such an extension could be made similar to lateral weather barrier  26 , only significantly shorter. The extension can include cavity  31  to reduce compressive forces at the boot. 
         [0042]    At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following: 
         [0043]    In some examples, a dock apparatus includes a retractable head curtain that is more flexible about a horizontal axis than a vertical one. 
         [0044]    In some examples, the head curtain is supported by a resiliently compressible, creased foam panel. 
         [0045]    In some examples, the creases in the foam panel are created by sewing the foam panel to a pliable cover using a series of horizontal stitch lines. 
         [0046]    In some examples, the foam panel is removably attached to the head curtain. 
         [0047]    In some examples, the head curtain is removably attached to a support panel. 
         [0048]    In some examples, the support panel is stiffened by a readily replaceable fiberglass stay. 
         [0049]    In some examples, the lower end of the head curtain is stiffened by a readily replaceable fiberglass stay. 
         [0050]    In some examples, the dock apparatus includes a pair of protective boots that are readily replaceable. 
         [0051]    Although certain example methods, apparatus, and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.