Patent Publication Number: US-10774578-B2

Title: Door with supplementary hinge-side engagement

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to hinged closures such as doors and windows and, in particular, it concerns a hinged closure with supplementary engagement at the hinge-side of the panel. 
     In a wide range of applications, it is desirable to provide hinged closures with reinforcement. For example, in security doors, it is known to provide a number of pins projecting from the door which engage corresponding holes in the hinge jamb, thereby providing enhanced resistance to forces trying to force the panel away from the frame. 
     Such pins generally project within the plane of the panel, such that they do not oppose forces that would tend to pull the panel away from the hinge jamb within the plane of the door frame. Such forces may occur under a range of circumstances, such as when a panel becomes bowed under an impact or blast. 
     SUMMARY OF THE INVENTION 
     The present invention provides various embodiments of a hinged closure with supplementary engagement at the hinge-side of the panel. 
     According to the teachings of an embodiment of the present invention there is provided, an apparatus comprising: (a) an opening bounded by a frame including a hinge jamb, the frame defining a plane of closure; (b) a panel; (c) a hinge arrangement associated with the panel and the hinge jamb and configured to hang the panel relative to the opening so as to be swingable between an open position removed from the opening and a closed position in which the panel is aligned parallel to the plane of closure within the opening; and (d) an engagement configuration comprising: (i) a ledge located in fixed relation to the hinge jamb, and (ii) a flange rigidly associated with the panel, the engagement configuration being configured such that the panel swings freely between the open position and the closed position, and such that, when the panel assumes the closed position, the flange is brought into facing relation with the ledge such that force directed to displace the panel within the plane of closure away from the hinge jamb acts to bring the flange into engagement with the ledge. 
     According to a further feature of an embodiment of the present invention, the flange is part of a closed profile forming at least part of the panel. 
     According to a further feature of an embodiment of the present invention, the closed profile is formed from at least one layer of sheet metal bent to form the flange and the closed profile. 
     According to a further feature of an embodiment of the present invention, the closed profile is formed from a single piece of sheet material bent so as to form the flange and the closed profile. 
     According to a further feature of an embodiment of the present invention, the closed profile is an extruded profile. 
     According to a further feature of an embodiment of the present invention, the panel is formed from at least two sheets of metal each extending substantially an entire width of the panel. 
     According to a further feature of an embodiment of the present invention, the closed profile includes an elongated recess, and wherein the panel includes a sheet of metal formed with a lateral folded lip, the elongated recess and the lateral folded lip being configured for sliding interengagement. 
     According to a further feature of an embodiment of the present invention, the closed profile further comprises a shoulder, and wherein the hinge jamb further comprises an abutment surface, the shoulder and the abutment surface being deployed such that, when the panel assumes the closed position, the shoulder and the abutment surface are brought into facing relation such that force directed to displace the panel within the plane of closure towards the hinge jamb acts to bring the shoulder into engagement with the abutment surface. 
     According to a further feature of an embodiment of the present invention, the flange and the shoulder are in facing relation defining between them an elongated recess of the closed profile, and wherein the ledge and the abutment surface are integrated into a projecting ridge of the hinge jamb, the projecting ridge coming into engagement with the elongated recess when the panel assumes the closed position. 
     According to a further feature of an embodiment of the present invention, the hinge jamb further comprises an abutment surface, the abutment surface being in facing relation with the ledge so as to define therebetween an elongated hinge-jamb recess, the flange being deployed to engage the elongated hinge jamb recess when the panel assumes the closed position with the flange in facing relation with the abutment surface such that force directed to displace the panel within the plane of closure towards the hinge jamb acts to bring the flange into engagement with the abutment surface. 
     According to a further feature of an embodiment of the present invention, the flange is part of a flange-extension rigidly attached to the panel. 
     According to a further feature of an embodiment of the present invention, the flange extension is bolted to the panel. 
     According to a further feature of an embodiment of the present invention, the flange extension is geometrically interlocked with the panel. 
     According to a further feature of an embodiment of the present invention, the flange extension extends along a majority of a dimension of the panel parallel to the hinge jamb. 
     According to a further feature of an embodiment of the present invention, the hinge arrangement includes a hinge support strip fixedly attached to the hinge jamb and extending along a majority of a length of the hinge jamb, and wherein the ledge is provided by an internal face of a slot formed in and extending along, the hinge support strip. 
     According to a further feature of an embodiment of the present invention, the hinge support strip supports a plurality of hinge pin elements spaced along the hinge jamb, wherein a sum total length of the hinge pin elements is less than a sum total length of the ledge. 
     According to a further feature of an embodiment of the present invention, the engagement configuration is configured such that contact between the flange and the ledge occurs only on application of sufficient force to cause damage to the hinge arrangement. 
     According to a further feature of an embodiment of the present invention, the frame further comprises a strike jamb, and wherein the panel further comprises a lock mechanism having a locking element displaceable to engage the strike jamb. 
     According to a further feature of an embodiment of the present invention, the locking element is a hook element configured to engage the strike jamb so as, to oppose forces directed to pull the panel away from the strike jamb. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a front view of a door assembly, constructed an operative according to an embodiment of the present invention, including a panel closing a doorway; 
         FIG. 2  is a schematic isometric view of the door assembly of  FIG. 1  with the surrounding wall cut-away, the door assembly shown with the panel partially open; 
         FIGS. 3A and 3B  are enlarged schematic isometric views of a region of the panel of  FIG. 1  illustrating a locking element in a retracted and a deployed state, respectively; 
         FIGS. 4A and 4B  are enlarged isometric views of the door assembly of  FIG. 1  illustrating an engagement configuration of the door assembly, shown with the panel in a closed and a partially-open state, respectively; 
         FIGS. 5A-5C  are partial horizontal cross-sectional views taken through the door assembly of  FIG. 1  showing the region of the hinge jamb with the engagement configuration with the panel in a closed state, partially-open state and fully-open state, respectively; 
         FIG. 5D  is a view similar to  FIG. 5B  taken at a different height such that it does not intersect the a pin element of the hinge; 
         FIGS. 5E and 5F  are partial enlarged views of two variant implementations of an engagement configuration shown in  FIG. 5A ; 
         FIG. 6  is a partial, cut-away isometric view of the door assembly of  FIG. 1  illustrating a variant implementation of an engagement configuration, constructed and operative according to an embodiment of the present invention, shown with the panel in a closed state; 
         FIG. 7A  is a horizontal cross-sectional view taken through the embodiment of  FIG. 6  with the panel in a closed state, the cross-section being taken in a region of a hinge pin, element; 
         FIGS. 7B-7D  are horizontal cross-sectional views taken through the embodiment of  FIG. 6  not passing through a hinge pin element, shown with the panel in a closed state, a partially-open state and a further-open state, respectively; 
         FIG. 8  is a partial, cut-away isometric view of the door assembly of  FIG. 1  illustrating a further variant implementation of an engagement configuration, constructed and operative according to an embodiment of the present invention, shown with the panel in a partially-open state; 
         FIGS. 9A and 9B  are horizontal cross-sectional views taken through the embodiment of  FIG. 8 , shown with the panel in a closed state and a partially-open state, respectively; 
         FIG. 10  is a partial, cut-away isometric view of the door assembly of  FIG. 1  illustrating a further variant implementation of an engagement configuration, constructed and operative according to an embodiment of the present invention, shown with the panel in a closed state; 
         FIGS. 11A and 11B  are horizontal cross-sectional views taken through the embodiment of  FIG. 10 , shown with the panel in a closed state and a partially-open state, respectively; 
         FIG. 12  is a partial, cut-away isometric view of the door assembly of  FIG. 1  illustrating a further variant implementation of an engagement configuration implemented with a panel including a closed profile formed from a single sheet of material, constructed and operative according to an embodiment of the present invention, shown with the panel in a closed state; 
         FIGS. 13A and 13B  are partial, horizontal cross-sectional views taken through the door assembly of  FIG. 12 , shown with the panel in a closed state and a partially-open state, respectively; 
         FIG. 14  is a partial, cut-away isometric view of the door assembly of  FIG. 1  illustrating a further variant implementation of an engagement configuration implemented with a panel including a closed profile formed from two sheets of material, constructed and operative according to an embodiment of the present invention, shown with the panel in a closed state; 
         FIGS. 15A and 15B  are partial, horizontal cross-sectional views taken through the door assembly of  FIG. 14 , shown with the panel in a closed state and a partially-open state, respectively; 
         FIG. 16  is a partial, cut-away isometric view of the door assembly of  FIG. 1  illustrating a further variant implementation of an engagement configuration implemented with a panel including an extruded closed profile, constructed and operative according to an embodiment of the present invention, shown with the panel in a closed state; 
         FIGS. 17A and 17B  are partial, horizontal cross-sectional views taken through the door assembly of  FIG. 16 , shown with the panel in a closed state and a partially-open state, respectively; and 
         FIGS. 18A and 18B  are partial, horizontal cross-sectional views taken through further variant implementations of an engagement configuration, constructed and operative according to an embodiment of the present invention, shown in a closed state of the panel, modified for a thick panel implementation and a thin panel implementation, respectively. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is an apparatus that provides a closure to a doorway or other opening. 
     The principles and operation of apparatus according to the present invention may be better understood with reference to the drawings and the accompanying description. 
     By way of introduction, it should be noted that reference is made herein to “doors” and “doorways” as non-limiting typical examples, but that the corresponding description should be understood to apply equally to other types of openings, such as for example windows. 
     Referring now to the drawings,  FIGS. 1-5D  illustrate an apparatus constructed and operative according to an embodiment of the present invention. Generally speaking, the apparatus includes an opening  10  hounded by a frame including a hinge jamb  12 , typically in combination with a strike jamb  14  and a lintel  16 . The frame defines a “plane of closure”, which is intuitively defined as the plane of the opening to be closed by a closure (panel), typically corresponding to a plane intersecting with the frame around an entire periphery of the frame. 
     The apparatus also includes a panel  18  which is hung on (i.e., mounted to) hinge jamb  12  via a hinge arrangement  20  so as to be swingable between an open position removed from opening  10  and a closed position in which panel  18  is aligned parallel to the plane of closure within opening  10 . 
     It is a particular feature of certain preferred embodiments of the present invention that the apparatus is also provided with an engagement configuration including a ledge  22  located in fixed relation to hinge jamb  12 , and a flange  24  rigidly associated with panel  18 . The engagement configuration is configured such that it does not obstruct free swinging of the panel between the open position ( FIGS. 5B and 5C ) and the closed position ( FIG. 5A ), and such that, when the panel assumes the closed position, the flange is brought into facing relation with the ledge such that force directed to displace panel  18  within the plane of closure away from hinge jamb  12  acts to bring flange  24  into engagement with ledge  22 . 
     Certain preferred embodiments of the present invention thus provide greatly enhanced anchoring of panel  18  to hinge jamb  12 . Specifically, under conditions of high strain, such as from a blast wave or from a heavy mechanical impact, a panel may be subjected to forces sufficient to damage and compromise support of panel  18  via pin elements of hinge arrangement  20 . The engagement configuration illustrated here is highly effective even when forces act to try to separate panel  18  from hinge jamb  12  within the plane of closure, such as may occur on bowing of panel  18 . The engagement configuration of flange  24  and ledge  22 , which may advantageously extend along a greater portion of the height of the hinge jamb  12  than the extent of the hinge pin elements, and most preferably, along a majority of the height dimension of hinge jamb  12 , provides highly effective retention of panel  18  against separation from hinge jamb  12 , even under in-plane forces. 
     A further feature of certain embodiments of the present invention as illustrated here is that hinge arrangement  20  includes a hinge support strip  26  fixedly attached to an outward facing surface of hinge jamb  12  and extending along a majority of a length of the hinge jamb. In this case, ledge  22  is preferably provided by an internal face of a slot  28  formed in, and extending along, hinge support strip  26 . The use of hinge support strip  26  fixed to an outward facing surface of hinge jamb  12  renders this configuration of the present invention highly suitable for retrofit adaptation of a conventional doorframe. Since attachment is over a large area, for example via a series of spaced-apart bolts  30  (see  FIG. 1 ), hinge support strip  26  can be strongly anchored to hinge jamb  12  to withstand forces up to required specifications for a wide range of applications. 
     It should be noted that the principles of the present invention are applicable both to inward-opening and outward-opening panels. In cases in which a panel is outward-opening, the hinge support strip  26  may be rendered tamper-resistant by use of countersunk bolts with drilled-out heads, or by using through-the-wall anchoring elements which are secured from the inside of a building (not shown). In some cases, configurations in which the components forming the engagement configuration are completely concealed from view, such as those of  FIGS. 8-11B , described below, may be preferred for outward-opening panels. 
     According to one non-limiting preferred example illustrated here, the hinge axis  32  provided by hinge support strip  26  is located set-in from the edge of the panel, such that flange  24  which projects from the extremity of the door undergoes motion with an outward component at the end of the closing motion of the door, thereby engaging slot  28 . The hinge axis position is also outside the plane of the panel. In other words, if the main body of panel  18  is viewed as bounded by two planes, at the front and back surfaces of the panel, hinge axis  32  is, located outside the space bounded by those planes, and slightly spaced therefrom. This configuration also facilitates a large angle of motion of panel  18 , for example, in excess of 160°, and in some cases approximately 180°, as illustrated in  FIG. 5C . 
     As mentioned above, the hinge pin elements defining hinge axis  32  support panel  18  for normal hinged motion, but are not the primary load-bearing elements in case of extreme loading. For this reason, in certain preferred implementations, hinge support strip  26  supports a plurality of hinge pin elements spaced along hinge jamb  12 , where a sum total length of the hinge pin elements is less than a sum total length of ledge  22 . Typically, the engagement configuration is configured with a clearance space between the facing surfaces such that contact between flange  24  and ledge  22  occurs only on application of sufficient force to cause damage to hinge arrangement  20 . 
     The orientations of the facing surfaces of flange  24  (when the panel is closed) and ledge  22  as illustrated here are perpendicular to the plane of closure and run parallel to the length of hinge jamb  12 . Optionally, a slight undercut angle may be provided ( FIG. 5E ) so that, under a load, flange  24  and ledge  22  lock against each other and cannot be released without pushing the panel back towards the hinge jamb. Conversely, implementations with a slight release angle ( FIG. 5F ) also fall within the scope of the present invention, and this may provide additional design freedom for implementation of the engagement configuration so that it does not impinge on the freedom of swinging motion of the panel. Any such release angle should be sufficiently small that frictional engagement between surfaces of flange  24  and ledge  22  negates any tendency to slide across each other and release engagement under an applied load. 
     It should be appreciated that the hinge-side reinforcements of the present invention may be used to advantage with any and all types, of panels and locking mechanisms. In many cases, panel  118  features a lock mechanism having one or more locking elements  34  displaceable to engage the strike jamb. The lock mechanism may be any conventional lock mechanism, and for conciseness, will not be described here in detail. In certain particularly preferred implementations, some or all of locking elements  34  are hook elements ( FIGS. 3A and 3B ) configured to engage the strike jamb  14  so as to oppose forces directed to pull the panel away from the strike jamb. This engagement complements the supplementary hinge jamb side engagement so as to provide highly effective retention of panel  18  within the opening under a wide range of loading conditions. 
     Turning now to  FIGS. 6 and 7A-70 , these illustrate a variant implementation of hinge support strip  26  and flange  24 . In this case, hinge axis  32  is located to the side of panel  18  (not set in, from the edge as above), and the engagement configuration is formed by two complementary profiles. A first profile, integrated with hinge support strip  26 , extends outwards from hinge jamb  12  and bends over to provide ledge  22 . A second profile, bolted or otherwise fixed to (or integrally formed with) panel  18 , has a U-shaped profile which provides flange  24 . These profiles preferably extend along a majority of a height of the hinge jamb and panel, interrupted at a number of locations by a conventional hinge structure (see  FIG. 7A ). The resulting engagement configuration is structurally and functionally equivalent to that of  FIGS. 1-5D  described above, and will not be described here in further detail. 
     Turning now to  FIGS. 8-18B , these illustrate alternative configurations of the hinge side engagement of the present invention which require a modified (i.e., non-standard) hinge jamb structure. Specifically, in these cases, ledge  22  is formed as a ledge internal to hinge jamb  12 , within an internal recess  36  within hinge jamb  12 . This ensures that the engagement configuration is tamperproof when closed, and facilitates implementations for bearing particularly large loads. 
     In  FIGS. 8-11B , flange  24  as illustrated here is part of a flange-extension  38  rigidly attached to panel  18 . In the example of  FIGS. 8-9B , flange extension  38  is bolted to the panel by a set of spaced-apart bolts  40  anchoring the flange extension to the main part of panel  18 . Flange extension  38  preferably extends along a majority, and most preferably the entirety, of a dimension of panel  18 . In this case, the engagement configuration is spaced from the hinge arrangement  20  such that the engagement configuration can be continuous, or near continuous, along the height of panel  18 . 
     The example of  FIGS. 10-11B  is structurally and functionally equivalent to that of  FIGS. 8-9B , except that flange extension  38  is in this case geometrically interlocked with the panel  18 . The geometrical interlocking may be achieved by any suitable interlocking configuration such as, for example, a dovetail joint or a T-rail joint interconnection. Attachment of flange extension  38  may be performed by sliding the parts together prior to mounting of panel  18  on hinge jamb  12 . 
     Turning now to  FIGS. 12-18B , these illustrate a number of further implementations of the present invention in which flange  24  is part of a closed profile  50  forming at least part of panel  18 . In this context, the term “closed profile” is used to refer to a structural element formed from material with a wall thickness less than the overall dimension of the profile, and where the shape of the profile in cross-section is closed, or substantially closed, thereby giving the element enhanced structural strength. The profile may have openings in certain cross-sections corresponding to localized holes for venting, filling, attachment to other elements, or for any other reason. The profile typically has an enclosed volume, which may be empty (or contain air) to form a hollow profile, or may be filed with foam or other filler with desired structural, acoustic or other properties. Depending upon the manufacturing technique used, the profile may be formed open at its ends, and is typically plugged at one or both of its ends by a suitable cap, typically incorporated into a transverse element extending along the top and/or bottom edge of the panel knot shown). 
     In the examples of  FIGS. 12-13B and 14-15B , closed profile  50  is formed from at least one layer of sheet material, typically sheet metal, bent to form flange  24  and the closed profile. In the examples of  FIGS. 16-17B , an extruded profile is used to anchor a sheet-metal panel element. The use of sheet metal in the construction of panels, such as for doors, provides a range of advantages. Such panels are typically relatively low in cost to produce via processes such as roll-forming or press-forming, and provide considerable mechanical strength. In security and blast-protection applications, sheet metal can withstand high loads for a given weight by acting as a diaphragm across the opening. However, such properties are only exhibited if the sheet metal is reliably anchored at its periphery. The various embodiments of the present invention illustrated herein provide effective solutions for such anchoring at the hinge side of the panel. Analogous closed-profile structures (not shown) are preferably used also at the strike jamb side of the panel in combination with a suitable locking mechanism, such as the mechanism illustrated above with reference to  FIGS. 3A and 38 . 
     In the case of  FIGS. 12-138 , closed profile  50  is formed from a single piece of sheet material  52  bent so as to form flange  24  and closed profile  50 . Most preferably, the same single piece of sheet material also extends across a majority of the panel width, and typically also forms a closed profile at the opposite (strike jamb) side of the panel. Flange  24  is preferably formed by a part of the sheet folded back on itself to form a double-thickness flange. Optionally, the two thicknesses of the sheet forming flange  24  may be bonded together, for example, by spot welding or riveting. In order to provide enhanced rigidity, the folded edge of the sheet is preferably bonded to the part of the sheet against which it closes at bond  54  to form the closed profile. This bonding may be achieved by welding or any other suitable joining technique known for joining sheet metal. The bond  54  is preferably continuous, or at multiple locations sufficiently closely spaced as to provide rigidity similar to that which would be achieved by a continuous joint. 
     Turning now to  FIGS. 14-15B , these illustrate an alternative embodiment in which panel  18  is formed primarily from two layers  56   a ,  56   b  of sheet material which cooperate to form a closed profile exhibiting a projecting flange  24 . The two layers may meet and be joined at additional regions across the width of the panel, or may be joined only at the two edges. The panel is typically filled with, a suitable filler material (not shown). 
     Turning now to  FIGS. 16-17B , these illustrate a further embodiment of the present invention according to which closed profile  50  is implemented as an extruded profile. The extruded profile may be formed from any extrudable material suitable for forming part of a door or window panel. Particularly preferred examples include aluminum and aluminum alloys, as well as carbon fiber-reinforced polymers. 
     In the example illustrated here, the closed profile is configured for mounting and retaining a sheet  58  of material, typically sheet metal, which forms a structural part of the panel. To this end, closed profile  50  here includes an elongated recess  60  which has an opening of dimension to receive a single thickness of sheet  58  and a shaped internal channel. Sheet  58  is formed with a lateral folded lip  62 , which may be an L-shaped folded lip, or may be bent back on itself to form a doubled-over edge as shown here. Elongated recess  60  and lateral folded lip  62  are configured for sliding interengagement such that the folded lip can be slid into engagement with the shaped internal channel of recess  60  and is retained thereby against tension applied within the plane of the sheet. The hinge jamb engagement configuration provided by flange  24  and ledge  22  together with the anchoring of sheet  58  within recess  60  provides highly effective retention of sheet  58  on the hinge-jamb side of the panel. By using similar retention of sheet  58  in a strike jamb-side profile (not shown), and a suitable locking, mechanism for retaining the strike jamb-side profile to the strike jamb (such as that illustrated above with reference to  FIGS. 3A and 3B ), highly effective retention of sheet  58  is achieved, providing the aforementioned load-bearing properties of a diaphragm stretched across the opening in a light-weight and low-cost structure. 
     Turning now to a further preferred feature of certain embodiments of the present invention, it has been found that, depending upon the structure of the strike jamb-side locking mechanism and/or dependent upon circumstances in which a load is applied to try to pry the door away from the strike jamb, forces applied to the panel may sometimes include a large force within the plane of the closure towards the hinge jamb. 
     In the context of the particular ledge and flange interlocking of embodiments of the present invention, certain preferred embodiments of the present invention, have the hinge-side extremity of the panel located within a recess within hinge jamb  12 . Accordingly, certain particularly preferred embodiments of the present invention provide surfaces deployed to provide effective support to oppose forces acting to displace the panel towards the hinge jamb. 
     Specifically, referring by way of a non-limiting example to the embodiments formed with a closed profile  50 , the closed profile preferably features a shoulder  64 , and hinge jamb  12  preferably features an abutment surface  66 . Shoulder  64  and abutment surface  66  are deployed such that, when panel  18  assumes its closed position, shoulder  64  and abutment surface  66  are brought into facing relation such that force directed to displace panel  18  within the plane of closure towards hinge jamb  12  acts to bring shoulder  64  into engagement with abutment surface  66 . 
     In the particularly preferred examples of  FIGS. 12-18A , flange  24  and shoulder  64  are in facing relation, defining between them an elongated recess of closed profile  50 . Ledge  22  and abutment surface  66  are then advantageously integrated into a projecting ridge  68  of hinge jamb  12  that is deployed so that it comes into engagement with the elongated recess of profile  50  when panel  18  assumes its closed position. It will be noted in the geometrical arrangement of  FIGS. 12-18A  that a certain clearance is required between flange  24  and ledge  22  to allow the required relative motion under rotation about hinge axis  32  to the closed position of the panel. Shoulder  64  and abutment surface  66 , on the other hand, are preferably brought into close facing relation, typically with a clearance of no more than a few millimeters therebetween, and may in some cases be brought into direct contact, in the closed state of the panel. 
     Although illustrated here as being surfaces perpendicular to the plane of closure, it should be noted that shoulder  64  and abutment surface  66  may also be implemented with a range of different angles, analogous to the variant implementations of ledge  22  and flange  24  discussed above with reference to  FIG. 5A . 
     Turning finally to  FIGS. 18A and 18B , these illustrate how the abutment surfaces may need to be varied in order to provide bidirectional support against in-plane forces for a range of different panel thicknesses. In the case of  FIG. 18A , the form of closed profile  50  is essentially similar to that of  FIG. 17A , except that the profile is here shown schematically with a generic thick panel structure  68 . The aforementioned structure of an elongated recess between flange  24  and shoulder  64  is very suitable for providing the aforementioned bidirectional support. 
       FIG. 18B , on the other band, shows an implementation for use with a thin panel structure  70 , and where it is desired to employ a correspondingly thin structure for closed profile  50 . In this case, hinge jamb  12  is preferably implemented with an abutment surface  66  in facing relation With ledge  22  so as to define therebetween an elongated hinge-jamb recess. Flange  24  is deployed to engage this elongated hinge-jamb recess when the panel is in its closed position with a surface of flange  24  in facing relation with abutment surface  66  such that force directed to displace panel  18  within the plane of closure towards hinge jamb  12  acts to bring flange  24  into engagement with abutment surface  66 . 
     It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the scope of the present invention as defined in the appended claims.