Abstract:
An elevator door panel for closing the opening to an elevator shaft comprising a generally planar steel sheet reinforced on the shaft side by a perimeter framework and intermediate vertical stiffening members. At its lower edge the panel includes a resilient seal member supported on a structural steel construction that is generally symmetrical about a vertical plane at a mid-section of the panel thickness.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to elevator door construction and, in particular, to the type of freight elevator doors that open and close with vertical motion.  
         SUMMARY OF THE INVENTION  
         [0002]    Freight elevators, sometimes referred to as cargo lifts or goods lifts, typically have vertically operating doors at their landings or floors. The doors can be of several different styles, one of the more common being a bi-parting unit. Various other known door styles in which the door construction has a panel that opens vertically upwardly is adaptable to the present invention. To protect personnel and property, the lower edge of the upwardly opening panel is typically fitted with a resilient astragal. The resilient astragal reduces impact forces when the lower edge of the upper panel contacts a person or object.  
           [0003]    Traditionally, the panels making up the landing doors are fabricated with a rigid frame made up of structural elements such as angle iron. Sheet steel is attached to the structural framework, typically by welding.  
           [0004]    It is important that the resilient astragal, besides serving to cushion impacts, serves to work as a fire stop in the event of a fire and continues to seal against a surface for a minimum period of time. The performance of the astragal is dependent not only on its construction, but also on the ability of the structural part of the door to which it is attached to maintain its integrity and shape. In the event of a fire, structural door elements can distort by bending out of their original plane and may make it difficult or impossible for an astragal to maintain its seal against the surface with which it seats.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention provides a door panel for a freight elevator with an astragal assembly that affords improved seal performance in a fire and that can be manufactured more economically than certain prior art designs.  
           [0006]    As disclosed, the door panel is fabricated primarily of steel sheet stock. At a lower edge of the panel, a resilient astragal hangs supported from a unique structural steel assembly. The astragal supporting structure has been found, surprisingly, to resist bending and excessive buckling of the door assembly to a greater extent than is experienced with prior art designs that involve more massive structures. The result is a door panel that has less material content and labor cost-but which resists heat distortion to a greater extent than a door panel construction it replaces. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is an elevational view from the shaft side of a flush-type upper panel of an elevator door;  
         [0008]    [0008]FIG. 2 is a horizontal sectional view of the panel of FIG. 1 taken in the plane  2 - 2  indicated in FIG. 1;  
         [0009]    [0009]FIG. 2A is an enlarged fragmentary view of a portion of FIG. 2;  
         [0010]    [0010]FIG. 3 is a vertical sectional view of the panel of FIG. 1; and  
         [0011]    [0011]FIG. 4 is an enlarged fragmentary view of a portion of FIG. 3 at the location of a lower edge and a resilient astragal of the panel.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]    Referring now to the figures, an elevator door panel or assembly is designated by the numeral  10 . The panel or assembly  10  in the illustrated example is an upper panel of a regular bi-parting style door. As will be understood by those skilled in the art, the invention can be applied to other door panel configurations including extended, pass and compound bi-parting door panels. The panel  10 , thus, is representative of any of a variety of other vertically sliding landing doors for closing the opening in a room to an elevator shaft and to a freight elevator car. The panel  10  is primarily a steel weldment comprising a rectangular, planar steel sheet or plate  11  reinforced by peripheral stiffening members  12 ,  13  and  14  at its upper horizontal edge  16 , vertical side edges  17 , and bottom horizontal edge  18 , respectively, and by intermediate vertical steel stiffening members  19  in its mid-section. The stiffening members  12 ,  13 ,  14  and  19  are all disposed on a side of the panel sheet  11  facing the elevator shaft. The various stiffening members  12 ,  13 ,  14  and  19  are suitably welded together at their intersections and at zones of contact with the sheet  11 . The sheet  11  depending on service conditions and/or size, can be 14 or 12 gauge stock, for example. The upper member  12  is, for instance, a 2½″×2″×{fraction (3/16)}″ steel angle. Alternatively, by way of example, the upper edge stiffening member can be a 2½″×2″×1″ Z-bracket (shown in phantom at  21  in FIG. 3).  
         [0013]    The side stiffening members  13  are, for example, 2″×2″×{fraction (3/16)}″ steel angle. The intermediate stiffening members  19  are, for instance 6″×1⅝″ channels which have a hat-shaped cross section, as shown in FIG. 2A, fabricated from 14 gauge steel. Angled toe, guards  22  of 12 gauge steel sheet material, for example, are welded between the upper ends of adjacent stiffener members  13 ,  19 . The width of the panel  10  can range from about 6′ to about 25′ as required by a particular application. A shoe bar angle  23  is bolted to each of the stiffener side angles  13 . A pair of slotted guide shoes  24  are bolted to each of the shoe bars  23 . The guide shoes  24  on each side of the panel  10  receive parallel vertical guide rails fixed to the elevator shaft for limiting movement of the panel to a vertical plane.  
         [0014]    The lower or bottom edge  18  of the panel  10  is stiffened by an astragal assembly  14 . The assembly  14  comprises several elongated structural steel members  26 ,  27  and  28  and a pair of fire-resistant, resilient sheets  31 ,  32  folded into U-shapes with one  31  nested within the other  32 . The structural steel members include an elongated flat, for instance, ¼″ to 1″ thick, depending upon application, by 2″ wide. Below the flat  26  is a major inverted channel  27  and a minor inverted channel  28  nested within the major channel. The major channel  27  is welded to the flat  26  at points  33  spaced along their lengths. The minor channel  28  is plug welded as typically shown in FIG. 4 at  34  at locations spaced along their length. The width of the minor channel  28  is such that when it is centered in the major channel  27 , there is space indicated at  36  between each of its flanges and an adjacent flange  38  of the minor channel  28  sufficient to receive the two layers of the sheets  31 ,  32 . Adjacent each end of the panel  10 , a bumper assembly of a short steel flat  39  and a short half-round steel bar  41  are welded in place, the half-round to the flat and the flat to the inner channel flanges  38 . The bumper assemblies, designated  40 , serve to limit the compression of the resilient astragal sheet material when the panel  10  is closed against a mating lower panel (or sill). The resilient astragal sheets  31 ,  32 , are retained by carriage bolts  42  spaced along the length of the panel  10  at suitable centers of, for example, 8″. Grommet nuts  43  are used to hold the bolts  42  in place. The astragal sheets  31 ,  32  are preferably formed of a neoprene-coated pyroglas, with the inner layer being about {fraction (1/16)}″ thick and having a weight of about 5 lbs. per square yard and the outer layer being about ⅛″ thick and weighing about 6.3 lbs. per square yard.  
         [0015]    With reference to FIG. 3, counterweights  47  can be used in a known manner to balance the door panel  10  with a lower panel. An opening in the wall of a building is represented at  48 ; a lintel of the opening is shown at  49 .  
         [0016]    It has been found that, unexpectedly, the disclosed astragal assembly, while having less mass and less section modulus about a vertical mid-plane than prior art structures performs more satisfactorily in fire tests than prior art designs and by virtue of its reduced mass and simpler geometry reduces material and labor costs. While this phenomena is not fully understood, it is believed to be due, at least in part, by the symmetry of the astragal parts about a central vertical plane. As an alternative design, a 2″×1″ steel angle  46  of relatively light gauge stock (e.g. 7 GA.) can be employed across the full width of the panel  10  and suitably welded between the stiffener  19  and flat  39 .  
         [0017]    It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.