Patent Publication Number: US-8113265-B2

Title: Washdown door

Description:
FIELD OF THE DISCLOSURE 
     This patent generally pertains to doors and, more specifically, to doors that can be periodically washed down to kill bacteria and other microorganisms. 
     BACKGROUND 
     General-purpose, vertically operating doors often have a flexible curtain that opens by rising from a vertical set of tracks installed alongside a doorway. Upon rising, the curtain transfers from the vertical tracks over to an overhead storage system. The actual design of the storage system may vary depending on the available space above the doorway and other considerations. An overhead storage system, for example, can be in the form of a take-up roller that draws in the curtain to open the door, or the storage system can be a set of horizontal, vertical, inclined, or coiled tracks that lead to the set of vertical tracks alongside the doorway. 
     Some vertically operating doors also include some type of protective breakaway feature that allows the curtain to temporarily separate from its guide tracks in the event of a collision such as, for example, the door&#39;s curtain being accidentally struck by a forklift passing through the doorway while door is only partially open. 
     Due to a vertically operating door&#39;s numerous intricate parts such as the door&#39;s vertical tracks; seals; overhead storage system; breakaway feature; and even the curtain itself, which can be comprised of multiple interconnected sheets and perhaps a window, such doors can be difficult to keep clean in environments that demand cleanliness. Many doors in the food and drug industry, for instance, need to be periodically washed down and sanitized in order to prevent product contamination. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of one example of a washdown door shown in a closed position. 
         FIG. 2  is a front view of  FIG. 1  but showing the door partially open. 
         FIG. 3  is a front view of  FIG. 1  but showing the door fully open. 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 1 . 
         FIG. 5  is a cross-sectional view similar to  FIG. 4  but with a different storage track. 
         FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 4 . 
         FIG. 7  is a cross-sectional view similar to  FIG. 6  but showing the storage track being machined. 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 1 . 
         FIG. 9  is a cross-sectional view similar to  FIG. 8  but some parts removed. 
         FIG. 10  is a cross-sectional view similar to  FIG. 4  without the removed parts of  FIG. 9 . 
         FIG. 11  is a cross-sectional view taken along line  11 - 11  of  FIG. 1 . 
         FIG. 12  is a cross-sectional view taken along line  12 - 12  of  FIG. 1 . 
         FIG. 13  is a front view similar to  FIG. 1  but showing a different door example. 
         FIG. 14  is a cross-sectional view taken along line  14 - 14  of  FIG. 13 . 
         FIG. 15  is a front view similar to  FIGS. 1 and 13  but showing another door example. 
         FIG. 16  is a cross-sectional view taken along line  16 - 16  of  FIG. 15 . 
         FIG. 17  is a front view similar to  FIGS. 1 ,  13  and  15  but showing yet another door example. 
         FIG. 18  is a cross-sectional view taken along line  18 - 18  of  FIG. 17 . 
         FIG. 19  is an exploded perspective view showing one example of a curtain&#39;s lower edge assembly. 
         FIG. 20  is a perspective view showing the example curtain&#39;s lower edge assembled. 
     
    
    
     DETAILED DESCRIPTION 
     Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify the same or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. Additionally, several examples have been described throughout this specification. Any features from any examples may be included with, a replacement for, or otherwise combined with other features from other examples. 
     Vertically operating doors include numerous intricate parts such as the doors&#39; vertical tracks; seals; overhead storage system; breakaway features; and even the curtain itself, which can be comprised of multiple interconnected sheets and perhaps a window. As a result, these doors can be difficult to keep clean in environments that demand cleanliness. Simpler doors might be easier to washdown; however, such doors lack the benefits of the otherwise preferred doors that have more features. 
       FIGS. 1-4  show an example a door  10  with various washdown features that make door  10  particularly suited for use in environments that demand cleanliness. Door  10 , for example, is useful in the food and drug industry where products and processes are regulated to ensure quality control. To prevent product contamination, such as bacteria and other microorganisms, some example features of door  10  include a solid block curtain storage track  12  with a spiral groove  14 , a combination ventilated side frame  16  and a pair of tracks  18  with a removable seal  20 , and various curtain seams (e.g., seams  22  and  24 ) that promote and direct liquid runoff to avoid water-holding pockets and surfaces. It should be noted, however, that door  10  can be used in any application and not just those with high cleanliness requirements. 
     Although the actual design details and operation may vary, door  10  is shown comprising a curtain  26  that moves vertically along tracks  18  to open and close the door  10 .  FIGS. 1 and 4  show door  10  closed,  FIG. 2  shows door  10  partially open, and  FIG. 3  shows door  10  fully open to expose a doorway  28 . Doorway  28  is defined by an upper edge  30  and two lateral edges  32  of a wall  34 . In the closed position, curtain  26  is held across doorway  28  between the pair of tracks  18 . In the open position, curtain  26  can be stored above doorway  28  and supported by various means including, but not limited to, coiling by virtue of being guided in storage track  12  ( FIGS. 4 and 6 ), wrapped upon an overhead roller, or supported by a generally linear storage track  36  ( FIG. 5 ). For the example of  FIGS. 1-4 , a transition piece  38  with a series of rollers  40  guides the transfer of curtain  26  between track  18  and storage track  12 . In the alternative example of a horizontally moving door (not shown), the curtain could be stored off to the side of the doorway. 
     In the illustrated example, curtain  26  is powered open and closed by a drive motor  42  that rotates a horizontal shaft  44 . At either end of horizontal shaft  44 , a cogged drive wheel  46  meshes with a series of protrusions  48  on lateral edges  50  of curtain  26 . Depending on the cogged drive wheel&#39;s  46  rotational direction, cogged drive wheel  46  pushes curtain  26  up to open door  10  or down to close the door  10 . Alternatively, the cogged drive wheel  46  could have protrusions (not shown) that mesh with a series of matching holes (not shown) in the lateral edges  50  of the curtain  26 . Many other ways of powering a door open and closed are certainly within the scope of this disclosure. 
     Referring to  FIGS. 4 ,  6  and  7  to avoid creating pockets of stagnant water in which bacteria may grow, storage track  12  preferably is machined as a seamless, unitary block of plastic with appropriate drainage at key locations. Storage track  12 , for example, includes a face surface  52  into which is milled a continuous spiral groove  14  by way of at least one shaped end mill  54 . A resulting cross-sectional area  56  of spiral groove  14  has a relatively narrow curtain-receiving mouth  58  and a deeper wider area  60 . As can be seen in  FIGS. 6 and 7 , the relatively narrow curtain-receiving mouth  58  is adjacent to face surface  52  and leads to the deeper wider area  60 . Such cross-sectional area  56  enables storage track  12  to capture and hold the curtain&#39;s protrusions  48  within spiral groove  14  while enabling curtain  26  to slide along the spiral groove&#39;s  14  relatively narrow curtain-receiving mouth  58 . 
     To avoid retaining stagnant water or other liquids and to enable drainage of any low-lying pockets, the inside lower surfaces of spiral groove  14  preferably are curved or inclined with a drain passageway  62  of some sort leading from those surfaces. Drain passageway  62 , for example, can be a drilled hole  64  leading to a lowermost point  66  of wider area  60 , and/or drain passageway  62  may include an opening  68  ( FIG. 4 ) where curtain  26  enters spiral groove  14 .  FIG. 7  shows a drill bit  70  creating drain passageway  62  by drilling the substantially cylindrical, linear hole  64  that leads to a plurality of discrete points  66 ′ or low-lying pockets in spiral groove  14 . As an alternative to a single drilled hole, multiple holes could be drilled from a backside  72  of storage track  12 , wherein each hole leads to a discrete point  66 ′. Another alternative would be to mill a slot in backside  72 , wherein the slot would extend into spiral groove  14 , break out through a bottom edge  74  of storage track  12 , and connect points  66  and  66 ′ in fluid communication with each other. 
     Referring to  FIGS. 8-10 , to help prevent water and other liquids from collecting on track  18  and to make the track  18  area easier to washdown and sanitize, door  10  includes removable seal  20  and/or removable track  18 , and also includes a plurality of standoffs  76  that create ventilating air gaps  78  between side frame  16  (e.g., track-supporting side frame) and a mounting surface  80  of wall  34 . In this example, each standoff  76  may be a U-shaped, stainless steel channel that can be attached to a backside of side frame  16  by way of a screw  82 , welding, or other means. Side frame  16  and standoffs  76  can then be attached to wall  34  by way of a conventional anchor bolt, welding (if mounting surface  80  can be welded), or by other attachment means. Side frame  16  preferably is made of a stainless steel to resist corrosion and to provide sturdy support for door  10  overall. 
     To seal off air currents  84  that might otherwise leak past through ventilating air gaps  78 , removable seal  20  extends between track  18  and wall  34 , as shown in the example, and/or removable seal  20  extends between side frame  16  and wall  34 . In either case, removable seal  20  is removably coupled to side frame  16 . The term, “removably” means the part is intentionally constructed such that it can be detached and later reattached without appreciable damage, wherein detaching is by way of disassembly as opposed to cutting, breaking or melting apart. Although track  18  and side frame  16  are shown as two separable pieces, which provides an important benefit, track  18  and side frame  16  could be a unitary piece, whereby side frame  16  would integrally include track  18 . Whether side frame  16  and track  18  are separable or a single piece, track  18  is still referred to as being “disposed on” side frame  16 . 
     By having track  18  and side frame  16  being separate pieces, as shown, side frame  16  can be heavy and strong for supporting door  10 , while track  18  can be of a plastic material that is lightweight and readily removable. Removing track  18  and removable seal  20  opens up ventilating air gaps  78  between wall  34  and side frame  16  so that those now-open areas can be washed periodically, and the removed parts can be washed separately. To facilitate frequent washings, track  18  preferably is “hand-removable,” which means that track  18  can be removed manually without using tools. To render track  18  hand-removable, track  18  is fastened to side frame  16  by way of a knurled nut  86  or wing nut that screws onto a screw  88  having a head  90  held within track  18 . 
     Although track  18  and removable seal  20  can be removed as a unit, the two pieces  18  and  20  preferably are a three-part assembly comprising a track case  18   a , a track liner  18   b , and removable seal  20 . By having three individual parts  18   a ,  18   b  and  20 , each piece  18   a ,  18   b  and  20  can be made of a material that is particularly suited for its intended purpose. Track case  18   a , for instance, can be made of polycarbonate because this plastic exhibits high impactability, broad temperature stability, is inherently non-corrosive, and can be flexed repeatedly and resiliently. The resilient flexibility enables the curtain&#39;s  26  lateral edges  50  and protrusions  48  to be forcibly yet restorably pulled out from within track  18  in the event of a forklift-curtain impact, thereby avoiding damage to door  10 . Track liner  18   b  can be made of UHMW (ultra high molecular weight polyethylene) for its excellent wear resistance. Removable seal  20  can be made of a neoprene, latex, silicone or similar rubbery material that can readily conform to the surface of wall  34 . All three parts  18   a ,  18   b  and  20  preferably are made of polymeric materials so that the three-part assembly together is sufficiently lightweight (e.g., less than 50 lbs.) for hand-removal. For the illustrated example, track  18  includes a flange  92  that press-fits into a slot  93  in removable seal  20 , thus removable seal  20  is hand-removable from track  18 . 
     In  FIG. 10 , it should be noted that U-shaped channel standoffs  95 , similar to standoffs  76 , are interposed between wall  34  and the backside of storage track  12  and transition piece  38 , thereby providing spaced-apart ventilation in those areas as well. 
     Returning to  FIG. 1  with further reference to  FIGS. 11 and 12 , curtain  26  includes inclined, moisture-guiding seam  22  that promotes and directs liquid runoff toward one or more of the curtain&#39;s  26  lateral edges  50 . The term, “seam” means a joint. Further, the “seam” or joint may result from two ends of fabric butting up against each other, but may also include overlapping joints. Such overlapping joints may be preferable here, as they yield “free” fabric edges that serve as collection and runoff paths for liquids, especially when inclined as described below. The joint, for example, can be glued, sewn, taped, thermally welded, ultrasonically welded, intermolecularly bonded, etc. The term, “incline” means that the seam is sloped and is thus neither perfectly vertical nor perfectly horizontal. The seam  22  being at an appreciable incline avoids creating water-holding surfaces on curtain  26  itself and directs drips off to the side of doorway  28 , thereby minimizing the possibility of liquid dripping onto products passing directly underneath curtain  26 . Seams  22  and  24  preferably are at a slope of at least 0.033 and preferably at least 0.050 with the slope values being in terms of vertical rise over horizontal run. Seams at shallower inclines are certainly possible and well within the scope of this disclosure. 
     For sake of example,  FIG. 11  shows seam  22  being a lap joint  97  between an upper pliable sheet  94  of curtain  26  and a lower pliable sheet  96  of curtain  26 . On one side of curtain  26 , lap joint  97  provides an upward-facing ledge  98  along which liquid may flow away from the center of doorway  28 . On the opposite side of curtain  26 , lap joint  97  provides a downward-facing ledge  100 . By dispersive adhesion, water can cling to downward-facing ledge  100  and run along that downward-facing ledge  100  toward the curtain&#39;s  26  lateral edge  50 . 
       FIG. 12  shows seam  24  disposed along an outer periphery of a window  102 . Curtain  26  and a transparent sheet  104  of window  102  can each be considered as either an upper pliable sheet or a lower pliable sheet, depending on their relative positions. In this example, seam  24  is created by an intermediate sheet  106  coupling transparent sheet  104  to curtain  26 . An upward-facing ledge  108  of seam  24  is sloped to convey water off to either lateral edge of window  102 . A downward-facing ledge  110  of seam  24 , lying along an incline, relies on dispersive adhesion to also direct water off to the side. A pair of upward-facing ledges  112  of seam  24  slope downward toward the center of window  102  to direct water down through a gap  114  between the two upward-facing ledges  112  and between curtain  26  and transparent sheet  104 . Liquid draining down through gap  114  and down around window  102  can be captured by the lower seam  22 , which then directs the liquid off to the curtain&#39;s  26  lateral edge  50 . 
       FIGS. 13 and 14  show a moisture-guiding seam  116  similar to seam  22 . In this example, moisture-guiding seam  116  is at a joint between slightly modified upper and lower pliable sheets  94   a  and  96   a . Moisture-guiding seam  116  peaks near the center of doorway  28  and slopes downward in either direction to direct water toward both lateral edges  50  of a curtain  26   a . A window  102   a  is in a diamond shape to create inclined water-conveying ledges but is otherwise similar in construction to that of window  102 . Window  102   a  has a gap  114   a  similar to gap  114  of window  102 . 
       FIGS. 15 and 16  show an inclined moisture-guiding seam  118  provided by an intermediate sheet  120  joining an upper pliable sheet  94   b  of a curtain  26   b  to a lower pliable sheet  96   b  of curtain  26   b . In this example, inclined moisture-guiding seam  118  includes two upward-facing ledges  122  and  124  that can direct water off to the curtain&#39;s  26   b  lateral edge  50 . A window  102   b  is generally round to create downward-curving, water-conveying ledges but is otherwise similar in construction to that of windows  102  and  102   a . Window  102   b  has a gap  114   b  similar to gap  114  of window  102 . 
       FIGS. 17 and 18  show a curtain  26   c  with two add-on sheets  126  that provide moisture-guiding seams  128 . Each moisture-guiding seam  128  has an upward-facing ledge  132  that lies at an incline to direct water off to the curtain&#39;s  26   c  lateral edge  50 . In this example, curtain  26   c  is a continuous, unitary sheet. Although curtain  26   c  comprises an upper pliable sheet  26   c ′ and a lower pliable sheet  26   c ″, sheets  26   c ′ and  26   c ″ are an integral extension of each other, so moisture-guiding seam  128  does not join sheets  26   c ′ and  26   c ″, but rather each moisture-guiding seam  128  is created by add-on sheet  126  being joined to the face of curtain  26   c.    
       FIG. 17  also shows a window  102   c  in the shape of a parallelogram to create inclined upper and lower water-conveying ledges but is otherwise similar in construction to that of window  102 . Window  102   c  has a gap  114   c  similar to gap  114  of window  102 . 
     To avoid or minimize water dripping near the center of the doorway (e.g., doorway  28 ) from a lower edge  134  of curtain  26  and to seal off perhaps a rough cut edge  136  at the bottom of curtain  26 , lower edge  134  can be finished as shown in  FIGS. 19 and 20 . In this example, a finishing sheet  138  begins as a generally rectangular sheet that is folded at a diagonal to create two moisture-guiding seams  140  and  142  with upward-facing ledges  132  that, on opposite faces of curtain  26 , slope downward in opposite directions toward either lateral edge  50  of curtain  26 . The slope angle of moisture-guiding seams  140  and  142  preferably are similar to the other example moister-guiding seams disclosed herein. Finishing sheet  138  can be attached to curtain  26  by various means including, but not limited to, adhesively taping, gluing, welding, sewing, etc. In some examples, joining finishing sheet  138  to curtain  26  preferably is done with adhesive tape, which provides additional thickness for the upward-facing ledges  132  of moisture-guiding seams  140  and  142 . Finishing sheet  138  preferably overlies lateral edges  50 ; however, lateral edges  50  overlying finishing sheet  138  is also well within the scope of this disclosure. 
     In some examples of the moisture-guiding seams  140  and  142  and ledges  100  and/or  132  (e.g., water-conveying ledges), it may be beneficial to have certain surfaces more water repellant than adjacent surfaces. The expression, “more water repellant,” as used herein means a surface having less strength of adhesion to water, thus water will tend to cling to surfaces that are less water repellant than to surfaces that are more water repellant. In the example of  FIG. 18 , making add-on sheet  126  more water repellant than the adjacent surface of curtain  26   c  will urge water to cling more to curtain  26   c  instead of running straight down off of upper-facing ledge  132 . In the example of  FIG. 11 , water may have a greater tendency to cling to the downward-facing ledge  100  if the adjoining surface of lower pliable sheet  96  is more water repellant than the downward-facing surface of downward-facing ledge  100 . The water repellency of a sheet can be set or established by the sheet&#39;s material composition, surface coating, and/or the sheet&#39;s surface roughness. 
     At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following: 
     In some examples, a door with a pliable curtain includes an inclined seam that not only joins two component sheets of the curtain together but also provides a moisture-guiding ledge that directs curtain drainage toward a lateral edge of the curtain. 
     In some examples, a downward-facing ledge directs water along a downward slope off to a lateral edge of a door curtain. 
     In some examples, a door includes a curtain with a window, wherein water drains through a gap between a face of the curtain and a transparent sheet of the window. 
     In some examples, a door curtain has an inclined lowermost edge that is sufficiently pliable to lie flat against the floor when the door is closed. 
     In some examples, a door with a pliable curtain includes a seamless storage track machined from a single block of plastic, wherein the storage track includes a spiral groove with liquid drainage at all the low areas of the groove. 
     In some examples, a door includes a curtain guided by a vertical track, wherein the track is disposed on a side frame. A series of standoffs provides a washdown air gap between the side frame and the wall to which the frame is mounted. When not being washed down, a removable seal is installed to block off the air gap. 
     In some examples, a door includes a curtain guide assembly comprised of four main parts: a side frame, track case, track liner, and a seal, wherein each of the four parts are made of a different material. 
     In some examples, the curtain guide assembly is readily disassembled and reassembled without the need for tools. 
     Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of the 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.