Patent Publication Number: US-2005126720-A1

Title: Chain driven articulated door

Description:
FIELD OF THE INVENTION  
      The present invention relates to an articulated or rolling door and a drive system for opening and closing the door.  
     BACKGROUND OF THE INVENTION  
      Articulated doors are formed from a plurality of panels hingedly connected to one another. These types of doors are becoming more and more popular for many different uses. They are for example used to cover large openings to garages and warehouse spacing etc. They are further used as rear truck doors on large truck trailers.  
      In the past, articulated doors were typically made from wood or lightweight steel materials. More recently there have been developments with respect to plastic panels which have become particularly suitable for use in rolling door applications.  
      A conventional rolling door is provided with cables to opposite sides of the door. These cables are used to raise and lower the door. In many garage type setups an automatic control in the form of a bar secured to the roof of the garage and extending to the upper end of the door is used to provide automatic opening and closing of the door. These garage door controllers are further able to hold or lock the garage door in its closed position.  
      It is not known in the trucking industry to use the conventional automatic door opener for a truck trailer door. This is because of the overhead space limitations of the trailer. A conventional roll up truck trailer door is therefore manually operated and necessitates a door lock for securing the door in its closed position.  
     SUMMARY OF THE PRESENT INVENTION  
      The present invention provides a door system based on a chain drive for opening and closing an articulated door. The system of the present invention is one which has numerous different applications including truck trailer applications. In these particular applications the truck trailer door can be opened and closed using a power drive without having space limitation concerns.  
      In particular, a door assembly of the present invention comprises an articulated door formed from a plurality of preferably plastic panels hingedly connected to one another. Each of the panels has an end fitting. The end fitting of the panels are pivotally linked with one another to form a chain to the side of the articulated door.  
      The assembly further includes a rotatable toothed gear which engages the chain formed by the end fittings for opening and closing the articulated. The toothed gear may be a power driven gear. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above as well as other advantages and features of the present invention will be described in greater detail according to the preferred embodiments of the present invention in which;  
       FIG. 1  is a perspective view of the rear of a truck trailer provided with an articulated door according to a preferred embodiment of the present invention;  
       FIG. 2  is a perspective view of the ends of two connected panels from the door of  FIG. 1 ;  
       FIG. 3  is an exploded perspective view of one of the panel ends of  FIG. 2  fitted with a chain forming end fitting according to a preferred embodiment of the present invention;  
       FIG. 4  is an exploded perspective view of the drive system for engaging the panel end fitting of  FIG. 3 ; and  
       FIG. 5  is a side view showing operation of the drive system of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION ACCORDING TO THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION IN WHICH  
       FIG. 1  shows a truck trailer  1  provided with a roll up articulated door generally indicated at  3 . This door is formed from a plurality of door panels  5 .  
      A pair of these panels secured to one another are shown in  FIG. 2  of the drawings. As will be seen according to this preferred embodiment each of the panels comprises a resin wall  6  surrounding an interior region of the panel. When the panels are initially formed this interior region is hollow and then preferably filled with a foam material  9 .  
      The panels are all identical in construction with one another. Each panel includes a curved tail  11  at one end of the panel and a correspondingly shaped slot  13  at the other end of the panel. The tail of one panel fits into the slot of an adjacent panel to form a hinged joint between panels.  
       FIG. 3  of the drawings shows an end fitting generally indicated at  15  which fits into the open end  7  of each of the panels  5 . Preferably, there is an end fitting at each end of each panel.  
      End fitting  15  comprises a link part  17  provided with internal lugs  19  and spaces between the lugs. A roller  21  is rotatably trapped to one end of the link as shown in  FIG. 3 .  
      Provided on the outside surface of link  17  is a cover plate  23  with a plug part  25  projecting from plate  23 .  
      Like panel  5  end fitting  15  preferably has a resin base construction. The end fitting may be injection molded from a relatively hard durable plastic material such as nylon or the like. The panel on the other hand is preferably made in an extrusion or even a pultrusion process. Foam material  9  may be introduced to the interior of panel  5  as the panel is being formed. The pultrusion process lends itself particularly well to formation of the panel while simultaneously injecting the foam into the interior of the panel.  
      End fitting  15  is mounted to panel  5  by pushing plug part  25  of the end fitting into the open end  7  of the panel. The plug portion will then embed itself into the foam material to secure the fitting with the panel end. Adhesives may also be used to assist in securing the panel and the fittings to one another.  
      As an alternative method of securing the fitting with the panel, the plug part  25  of the fitting can be pushed into the open end of the panel before foaming. The injected foam will then fill the hollow interior of plug part  25 . The foam hardens within the plug part to secure the end fitting with the panel.  
       FIGS. 4 and 5  of the drawings shows how a chain is formed by connecting end-to-end end fittings between the side by side connected panels of door  3 . These figures also show how the chain engages with and is driven by a power drive system for opening and closing articulated door  3 .  
      In  FIG. 4  it will seen that a plurality of end fittings  15  are pivotally connected at the rollers  21  to one another. The rollers align with the pivotal connections between the panels. The links  17  of these end fittings form a length of chain. Each of the end fittings is plug fitted into an aligned one of the panels  5  to secure the chain along the edge of the door.  
      A drive system generally indicated at  35  operates in conjunction with the chain formed by the end fittings to raise and lower door  3 . This drive system comprises a rotary gear  39  having teeth  40 . Teeth  40  and more particularly the gaps between teeth  40  engage the lugs  19  of the chain links  17 .  
      Rotary gear  39  is attached to a second rotary gear  41  having teeth  42 . The teeth  42  of gear  41  engage with correspondingly shaped teeth of a transfer gear  43 . Transfer gear  43  is rotated by a power driven gear  45 .  
      The chain formed by the panel end fittings is guided in its up and down travel by means of a track  31  mounted to the interior of the truck.  
       FIG. 5  of the drawings shows the drive system as including a cable  51  having its one end  53  attached to gear  39 . The other end of cable  51  is attached at  55  to load biasing spring  57  secured at  59  to an inside surface of the truck body. The bias provided by spring  57  at the different up and down positions of the door is set to substantially offset weight of the door. As such the power required to drive system  35  is minimal e.g., simply enough to overcome inertia in starting the door to move from a stopped position.  
      As earlier noted the door assembly of the present invention will typically include a power drive system as described immediately above to both sides of the door for a balanced opening and closing of the door.  
      A further benefit provided by the power drive system is that when the main drive gear  45  is not in operation it is locked against rotation. This in turn locks up the rest of the assembly which eliminates the need for any type of an external lock on the door. As can be seen with respect in  FIG. 1  door  3  does not include an external door lock.  
      Although various preferred embodiments of the present invention have been described in detail, it will be appreciated by those skilled in the art that variations may be made without departing from the spirit of the invention or the scope of the appended claims.