Patent Publication Number: US-6336248-B1

Title: Suspension system for sliding door

Description:
TECHNICAL FIELD 
     This invention relates to suspension systems for sliding doors and particularly to suspension systems for sliding doors that are used in opening and closing doorways that provide ingress and egress from refrigerated spaces. 
     BACKGROUND OF THE INVENTION 
     Today most commercial kitchens, restaurants and supermarkets use swing doors to close and open space access doorways rather than sliding doors. This is primarily due to their lower cost. Swing doors however are ill suited for use in refrigerated spaces such as walk-in coolers since they must swing freely and thus have clearance with the doorway bounding jamb or wall. Such clearance of course permits air to flow between the refrigerated space and ambience beneath the door even though it is closed. Swing doors also require substantial swing space on each side of the wall. In effect this prevents the spaces along the walls from being used as corridors. They also pose the risk of striking people accidently when doors suddenly swing open. Conversely, sliding door systems have been devised that can seal a doorway. These systems have sealing gaskets either on the door jamb or the door. The sliding doors are suspended by systems that have been quite costly and complex. This complexity and cost has been driven by the need for the door to travel laterally over the doorway and yet towards and away from it as it is brought into sealing engagement with the door jamb gaskets. 
     Their suspension systems have included ramps which drive the door towards and away from the doorway and adjacent wall in sealing it. They have also included floor mounted guides which typically have had to be mounted atop or inset in concrete. These have been obstacles that have been hazardous to kitchen workers who often carry heavily loaded trays through the doorway. Floor mounted tracks also collect dirt and grime which is unsanitary. Their trolley systems have been complex with numerous parts as shown, for example, in U.S. Pat. No. 4,651,469. This type system is prevalent in Europe where it is known as the Fermod system. Swing doors, especially in smaller man access sizes, cannot readily be replaced with them, or retrofitted, because of their high cost, complexity and need for floor mounted guides and tracks. With larger sizes the high cost of conventional sliding doors is simply accepted as a necessity since a swing door could take up a whole room. They also require auxiliary jambs or sub-frames to support the weight of their suspension system. They also typically have a bulky industrial appearance. 
     Accordingly, it is seen that a need exists for a sliding door suspension system of simpler and less expensive structure that can be used effectively in opening and sealing a doorway such as one to a refrigerated space. It is to the provision of such that the present invention is primarily directed. 
     SUMMARY OF THE INVENTION 
     In a preferred form of the invention, a suspension system is provided for a sliding door that closes a doorway in a wall that is bounded by sealing gaskets. It is of relatively simple and light weight construction so that it can be mounted directly to the wall without the need for a sub-frame. The suspension system has an upper support rail from which the door is suspended by hangers and a lower guide rail along which the door is guided. The two rails are spaced from the wall at distances to have the door slide at a tilted angle over and out of contact with the sealing gaskets except at a doorway closed, sealing position where a spring biases the door firmly against the gaskets. By attaching the hangers inboard of the center of mass of the door, the weight of the door assists in effecting a good seal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a front view of a sliding door that is mounted with a suspension system that embodies principles of the invention in its preferred form. 
     FIG. 2 is a perspective view of one of the door hangers with a hanger roller riding along an upper support rail, shown with the covers removed. 
     FIG. 3 is an end view of the door showing how it travels at a tilt over the doorway gaskets. 
     FIG. 4 is a perspective view of a system guide mechanism that is mounted to the door in engagement with the lower guide rail. 
     FIG. 5 is an inverted rear view of the guide mechanism of FIG.  4 . 
     FIG. 6 is a top view of the guide mechanism of FIG.  4 . 
     FIG. 7 is an inverted end view of the guide mechanism of FIG.  4 . 
     FIG. 8A is a top view showing the guide mechanism about to reach an end portion of the lower guide rail while 
     FIG. 8B shows the mechanism at the end portion with the door in sealing engagement with the doorway gaskets. 
    
    
     DETAILED DESCRIPTION 
     With reference next in more detail to the drawing, there is shown in FIG. 1 a wall  10  having a doorway  9  that is bounded along its top and sides by resilient sealing gaskets  12 . The wall and doorway extended upwardly from a floor  13  such as one made of concrete. A sliding door  15  with handle  46  is mounted to the wall  10  for sliding movement between a closed position sealing the doorway closed and a doorway open position. Typically the doorway provides for access to a refrigerated space such as a commercial walk-in cooler. 
     The door is mounted by a suspension system that includes an upper support rail  16  that is covered by a cover  17 . The upper support rail is mounted to the wall over and to each side of the doorway  9 . The door  15  is movably suspended from the rail by means of two hangers  18  to which a hanger roller  19  is journaled. As shown in FIG. 2 the roller  19  has a curved bearing surface and travels along upper and lower curved bearing surfaces  20  of the upper support rail. These surfaces  20  are slightly wider than the curved bearing surfaces of the roller which permit the rollers to cock or tilt slightly as they it ride the rails. The center line of the rail bearing surface  20  is spaced from the wall mounted surface  21  at a selected distance. Adjustment means is provided to enable the door to be mounted at various heights. 
     With continued reference to the drawing the sliding door suspension system is further seen to include a lower guide rail  25 . As best shown in FIGS. 8A and 8B, the guide rail  25  has a long, linear portion  26  that merges with an inturned, end portion  27  that has a mounted flange  28  bolted to the wall  10 . The upright rail linear portion is mounted parallel with the wall  10  with its inside bearing surface that faces the wall being located a distance from the wall with respect to the selected distance that the centerline of the bearing surface of the upper rail is so mounted to cause the door to move at a tilt along the linear portion as shown in FIG.  3  and is hereinafter further explained. 
     The door is guided along the lower guide rail by a guide mechanism  30  that is shown in FIGS. 4-8. The mechanism is mounted to the edge  15 ′ of the door  15  by mounting a flange  31  of a bracket  32  flush thereto. A guide roller  33  and a guide pin  34  are rotatably mounted atop the bracket. A U-shaped swing arm  35  is pivotal mounted to the bracket by pivot pins  36 . The swing arm carried a push roller  38 . One end of a spring  40  is mounted to the push roller axle  39 . The other end of the spring is mounted to a mounting pin  42  that is mounted to the bracket  32 . The pin  42  is located relative to the roller axle  39  and swing arm pivot pin  36  such that rotation of the swing arm can cause the spring to become over centered and bias the push roller  38  and the swing arm to which it is mounted. The mechanism is mounted to the lower guide rail  26  so that the roller and pin straddle it with the push roller  38  in contact with the inside face of the rail it as shown best in FIGS. 8A and 8B. The mechanism is covered by a cover  44 . 
     Once mounted with the just described suspension system the door  15  may travel along the linear portion of the lower guide rail  27 , suspended from the upper support rail  16  with its bottom tilted away from the wall  10  as shown in FIG.  3 . Thus the plane of the door geometrically intersects the plane of the wall face and of the gaskets above them. As it travels in this orientation it is seen not to engage the doorway gaskets  12  by means of the relative location of the upper and lower rails. Also, a bottom gasket  45  on the bottom of the door is raised off the floor. Thus the door can glide easily unencumbered by gasket friction. Also the push roller  38  rolls free of the guide or in slightly rolling contact with it as shown in FIG.  8 A. The roller  33  and pin  34  maintain the rigid door in its tilted position since they straddle the rail  25 . 
     As the door approaches its closed position the roller  33  and pin  34  move off of the long linear position of the lower rail  26  and onto its inturned end portion  27 . This in turn causes the lower portion of the door to move towards the wall  10  and the angle of door tilt to decrease. Movement of the bracket  32  towards the wall also occurs as shown in FIG.  8 B. The spring  40  is brought to an over centered position as shown in FIG. 6 which causes it to bias the push roller  38  away from the wall  10  and against the rail  26 . As the door becomes upright its bottom gasket is also swung into engagement with the floor at the doorway. In this manner the doorway may become sealing closed virtually airtight. 
     It thus is seen that a suspension system is now provided for a sliding door that enables the door to be easily moved to and from an open position and yet which provides for a firm closing of a doorway. Where the doorway is bounded by sealing gaskets which is commonly for accesses to refrigerated spaces, the door may be slid open and closed without contact with the gaskets. Yet when the door is moved to a doorway closing position it is brought into firm sealing engagement with the gaskets. 
     Though the suspension system is principally designed for a door and doorway with peripheral sealing gaskets, it is useful too for doorways without such gaskets or for situations where sealing gaskets are mounted to the door instead. It can be mounted directly to a wall or wall panels since it is of such simple and lightweight construction. It presents a low profile appearance rendering it suitable for kitchen use. 
     While the system has been shown and described in its preferred form, it should be understood that many modifications, additions and deletions may be made thereto without departure from the spirit and scope of the invention as set forth in the following claims.