Patent Publication Number: US-6988528-B2

Title: Overhead door assembly

Description:
This application claims benefit to U.S. Provisional application No. 60/442,909 filed Jan. 28, 2003. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed to an overhead door assembly and more specifically to an overhead door assembly comprised of light weight insulated plastic panels having inter-fitting complementary top and bottom connecting portions extending the entire length of the panel. Moulded end caps are secured to opposite ends of each panel and include plastic brush material extending outwardly therefrom for sliding engagement in vertically extending tracks secured to opposite door jambs 
     The overhead door assembly according to the present invention is designed primarily for loading dock doors which are frequently subjected to collisions with forklift trucks or loads carried by fork lift trucks operating within the warehouse. For years the common thought has been that the best way to prevent damage to the overhead door panels is to make them thicker and stronger, sometimes including metal reinforcement plates or bars to make the doors more resistant to damage. However the increased weight necessitated the need for much larger and more powerful counter balance systems to raise the doors. Thus the overall expense of manufacturing and maintaining overhead doors has risen substantially over the years. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved overhead door construction comprising a plurality of interlocking elongated panels of insulated plastic material. A brush assembly is secured to each end of the panel and extends the entire height of the panel. The brush assembly fits within a channel of a track member mounted on the door frame so that the panels will become disengaged from the track should they be severely impacted by a forklift truck or the like. Thus the individual door panels remain substantially undamaged by the impact and can be easily reassembled with the brushes in the opposed tracks. In view of the extremely light weight construction of the overhead door only a small counterweight is necessary and can be guided in a bore extending the length of the track member. The counterweight is connected to the top of the door by a strap trained over a self aligning pulley. The door construction is so light that the overhead door can be raised and lowered by hand or by a small electric motor. Due to its light weight, the amount of energy that is transferred from impact is minimized, thus greatly reducing damage. Suitable weather seals are provided along the length of the top and bottom panels and the density of the brush materials enables the brushes to act as a weather seal along the opposite sides of the door. 
     The specific nature of the invention, as well as advantages thereof, will clearly appear form the following description and from the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an inside view of an overhead door assembly. 
         FIG. 2  is a perspective view of the inside of an overhead door panel with brush holding end caps attached thereto. 
         FIG. 3  is an end view of two interconnected door panels without the end caps. 
         FIG. 4  is an enlarged detail of the area designated by a circle B in FIG.  1 . 
         FIG. 5  is a perspective view of an end cap without the brush. 
         FIG. 6  is an end view of an end cap for the uppermost door panel of an overhead door assembly with one end of a weather strip mounted thereon for engagement with a door frame. 
         FIG. 7  is an end view of a door cap for a lowermost door panel with one end of a weather strip secured thereto for engagement with the floor of a structure. 
         FIG. 8  is a top plan view of a track member with a channel for receiving a brush assembly on a door panel and a counterweight passage with a counterweight disposed adjacent a magnet assembly. 
         FIG. 9  is a perspective view of the magnet assembly per se. 
         FIG. 10  is a perspective view of a side track member with the counterweight passage cover removed. 
         FIG. 11  is a perspective view of the counterweight passage cover per se. 
         FIG. 12  is a perspective view of a portion of the side track member showing the passages for reintroduction of the brush material of a door panel. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is an inside view of an overhead door assembly according to the present invention. A pair of parallel track members  20  are mounted on an interior wall of a structure on opposite sides of a door opening which is not visible in  FIG. 1  since the door is in the closed position relative to the door opening. Each track member  20  is provided with a channel  22  which is open and facing the other channel for the reception of a brush, not shown, mounted on opposite ends of each door panel  24 . Each track member  20  is further provided with a counterweight passage  26  for reception of a counterweight assembly  28  connected to the uppermost door panel  24  by means of a strap or cable  30  which extends over a pulley  32 . 
     Each door panel  24  as shown in  FIG. 3  is comprised of a hollow, light weight extruded plastic member having integral reinforcement panels  34  and  38  to maintain shape of each panel. Each panel is provided with an elongated rounded top portion  36  and a complementary rounded recess  40  along the bottom edge of the panel. Due to the complementary shape of the top projection  36  and the bottom recess  40 , adjacent panels can be rotatably connected relative to each other only by longitudinal insertion of the rounded portion  36  into the rounded recess  40  as best seen in FIG.  3 . The interior surface  42  of each panel  24  has an integrally moulded recess  44  adjacent the lower edge which defines a finger gripping portion  46  for raising and lowering the overhead door assembly. 
     Each door panel is flexible and will bend in a direction transverse to the length of the panel to absorb impacts and prevent damage to the panel. If the force of the blow is large enough the rounded portion  36  will separate from the recess  44  to limit any damage to the panel. The panels will return to their original shape and can be reassembled as mentioned above. 
     Each door panel  24  is provided with end caps  50  which are secured to opposite ends by means of rivets  52  or any other suitable means. Each end cap has a brush  54  comprised of a plurality of relatively stiff bristles secured in a channel  56  by an adhesive or any other suitable means. 
     An end cap  50  without the brush is shown in FIG.  5 . The end cap is provided with an end plate  58  having a shape which is complementary to the hollow interior of a door panel for closing the hollow interior when the end cap is secured to the end of the door panel. A pair of spaced apart elongate walls  60  are secured to the end surface  58  by welding or the like to define a channel  62  for the reception of a brush  54 . A plurality of reinforcing plates  64  are connected to the walls  60  and the end surface  58  to stabilize the walls  60 . A pair of parallel flanges are provided along opposite sides of the main panel  58  and have holes  68  for the reception of rivets or the like to connect the end cap  50  to the end of a door panel. The end cap  50  is also provided with a recess  44 ′ complimentary to the recess  44  in the door panel. The end cap is also provided with a rounded top portion  70  and a complimentary rounded recess  72  at opposite ends of the end cap which are complimentary to the projection  36  and the recess  40  on each panel.  FIG. 4  is an enlarged view showing the door panels  24  with the end caps  50  mounted thereon with brushes  54  disposed within the channels on the end caps. The brushes  54  are disposed within the channel of each track member  20 . 
       FIG. 6  is an end view of the top most door panel  24  of a door assembly. An elongated piece of weather stripping  74  is mounted in a bracket  76  which in turn is secured to an upper surface of the door panel by any suitable means such as rivets or the like. The weather stripping  74  extends the entire length of the door panel and is adapted to engage the interior surface of a door frame, not shown, when the overhead door assembly is in the closed position.  FIG. 7  is an end view of the lowermost door panel  24  of an overhead door assembly. An elongated piece of weather stripping  78  is secured in a bracket  80  which is secured in the rounded recess  36  of the lowermost door panel by any suitable means. Thus, the weather stripping  78  will extend the entire length of the lowermost door panel for engagement with the floor  82  of the structure as shown in FIG.  1 . The piece of weather stripping  74  or  78  may be a piece of flexible material such as rubber of a brush assembly. 
       FIG. 8  is a top plan view of a track assembly  20  as shown in FIG.  1 . The track member  20  is adapted to be mounted on an interior surface of a door frame, not shown, by means of a bracket  84  comprised of two L-shaped members  86  and  88  which are connected to each other by welding, fasteners or the like. The members  86  and  88  are extruded vinyl material and extend the entire length of the door opening. The member  88  which is to be mounted on a wall or a door frame is provided with a co-extruded piece of a vinyl weather stripping  87  extending the entire length of the member  88 . The track members  20  are each comprised of a main channel having three walls  90 ,  92  and  94  formed of one piece of metal material and disposed at right angles to each other as shown in FIG.  8 . The free ends of the walls  90  and  94  are provided with protrusions  96  and  98 , respectively, which define a channel for the reception of opposite edges of a curved channel cover  100 . A perspective of the track  20 , per se, without the cover  100  is shown in  FIG. 10 and a  perspective view of the cover  100  is shown in FIG.  11 . 
     A pair of parallel walls  102  and  104  protrude from the side wall  94  to define a channel  106  extending the length of the track member for the reception of the brushes  54 . As shown in  FIG. 8 , a counterweight  28  is movable up and down the channel in the track  20  by means of the cable  22  connected to the overhead door. A magnet assembly  110  is mounted in the channel adjacent the top thereof so that the counterweight will be disposed adjacent the magnetic assembly when the overhead door is in the closed position as shown in FIG.  1 . The magnet assembly  110  is comprised of a pair of mounting plates  112  and  114  mounted on the walls  94  and  92 , respectively of the channel, by any suitable means such as rivets or welding. A pair of parallel spaced apart plates  116  and  118  are connected to the mounting plates  112  and  114 , respectively, by hinge member  120  and  122 . A plurality of magnets  124 ,  126  and  128  are mounted between the two plates  116  and  118  by any suitable means such as an adhesive or the like. The lower edges of the plates  116  and  118  are beveled at  130  and  132 , respectively, so that when the counterweight  28  approaches the magnet assembly it will engage the beveled surfaces  130  and  132  and move to one side of the channel so that it can move into aligned relationship with the magnets  124 ,  126  and  128  without damaging the magnet assembly  110 . The magnets should be mounted in the magnet assembly with opposite poles adjacent to each other and the counterweight should be of magnetic material. The attractive force of the magnets will tend to hold the counterweight in the raised position thereby effectively reducing the weight of the counterweight which would tend to open the door in an undesirable manner. When the door is positively moved to an open position manually or otherwise the weight of the counterweight will be sufficient to overcome the magnetic force and the counterweight will descend within the channel to assist in the raising of the overhead door. 
     The upper portion of the guide track for the brushes defined by the parallel plates  102  and  104  is shown in  FIG. 12. A  pair of slots  140  and  142  are provided in the outside plate  102  and the inside plate  104 , respectively, to allow for the reinsertion of the brushes should one or more brushes on one or more door panels become disengaged from the track upon impact on the door from the inside of the door. The openings  142  in the inside panel  104  are shown in  FIG. 4  in conjunction with the door panels  24  and the brushes at each end of the door panels. The brushes would not ordinarily be damaged if they are forced from the guide tracks due to an impact on the door panels. But if the brushes are damaged in any way or become worn the brushes can be readily replaced. 
     The overhead door assembly according to the present invention provides an extremely lightweight assembly which can be raised and lowered manually. However a small electric motor could be associated with the cable for the automatic raising and lowering of the overhead door assembly upon operation of a switch. The panels can be filled with a light weight insulating material if desired. The provision of insulation material would not adversely affect the operation of the overhead door assembly. While the door assembly is provided with two vertically extending tracks  20  as shown in  FIG. 1  in a warehouse environment where sufficient clearance would be available it is also possible to provide curved tracks similar to those in conventional overhead door assemblies for residential garages. Since the individual door panels are pivotally articulated with respect to each other the door would readily adapt to such a curved track arrangement. 
     While the preferred embodiment has been described, variations thereto will occur to those skilled in the art within the scope of the present invention concepts.