Abstract:
An apparatus for increasing the ability of a &#34;double-door&#34; door assembly to withstand stresses caused by high winds and flying debris associated therewith. The door assembly includes first and second doors. The first door has a first pivot stile for pivotally coupling with the first door jamb, and a first meeting stile. The second door has a second pivot stile for pivotally coupling with the second door jamb, and a second meeting stile. The first meeting stile has a greater depth, measured in a plane normal to the plane of the first door, than the remainder of the first door. Similarly, the second meeting stile has a greater depth, measured in a plane normal to the plane of the second door, than the remainder of the second door.

Description:
FIELD OF THE INVENTION 
     The present invention pertains to door assemblies and, more particularly, but not by way of limitation, to improved apparatus and methods for increasing the ability of a &#34;double-door&#34;, aluminum door assembly to withstand stresses caused by high winds and flying debris. 
     HISTORY OF THE RELATED ART 
     The prior art is replete with various external door assemblies having a variety of designs, constructed from a variety of materials, and for use in either commercial or residential applications. One conventional door assembly, which is typically used for commercial applications, is an external aluminum door assembly. Such external aluminum door assemblies typically comprise a single door having an aluminum body surrounding a central glass panel, or two mating doors, each having an aluminum body surrounding a central glass panel, that open at the middle. It is highly desirable for such aluminum door assemblies to provide a weather seal when closed; to have sufficient structural integrity to withstand normal opening and closing; to be capable of being used safely; and to present a pleasing aesthetic appearance. 
     One conventional aluminum door assembly is shown in FIGS. 1 and 2. Referring first to FIG. 1, aluminum door assembly 10 has two doors 12 and 14. Door 12 has a parallel pivot stile 16a and a meeting stile 18a fixedly coupled to a parallel top rail 20a and a bottom rail 22a. Pivot stile 16a, meeting stile 18a, top rail 20a, and bottom rail 22a support a panel member 24a. Panel member 24a is typically constructed from building glass, polycarbonate, or other conventional glazing material. 
     Similarly, door 14 has a parallel pivot stile 16b and a meeting stile 18b fixedly coupled to a parallel top rail 20b and a bottom rail 22b. Pivot stile 16b, meeting stile 18b, top rail 20b, and bottom rail 22b support a panel member 24b. Panel member 24b is typically constructed from building glass, polycarbonate, or other conventional glazing material. 
     Doors 12 and 14 are pivotally mounted in a frame 26. Frame 26 typically comprises parallel door jambs 28a and 28b fixedly coupled to a parallel transom 30 and a threshold 32. Pivot stiles 16a and 16b are pivotally mounted to jambs 28a and 28b, respectively, by conventional means, such as hinges. Such conventional hinges are preferably mounted at points 34 as shown in FIG. 1 so as to insure the structural integrity of the coupling between pivot stile 16a and jamb 28a and pivot stile 16b and jamb 28b. Although not shown in FIG. 1, doors 12 and 14 may each comprise a handle to facilitate the opening and closing of the door. Such handles may be located on meeting stiles 18a and 18b, or such handles may span across panel member 24a between pivot stile 16a and meeting stile 18a and across panel member 24b between pivot stile 16b and meeting stile 18b. In addition, door 12 may have locking pins at points 150a and 152a on meeting stile 18a that mate with corresponding holes on transom 30 and threshold 32, respectively, and door 14 may have locking pins at points 150b and 152b on meeting stile 18b that mate with corresponding holes on transom 30 and threshold 32, respectively. 
     Referring now to FIG. 2, a cross-sectional view of meeting stiles 18a and 18b along line 2--2 of FIG. 1 is shown. Meeting stile 18a comprises substantially parallel webs 36 and 38 fixedly coupled to parallel webs 40 and 42. Web 36 has tongues 44a, 46a, and 48a on its exterior surface, and web 38 has a generally convex geometry for interfacing with meeting stile 18b. Meeting stile 18a further comprises a glazing stop 50a. Glazing stop 50a has resilient legs 52, 54, 56, and 58 that engage tongues 44a, 46a, and 48a, respectively. Resilient legs 52, 54, 56, and 58 may be disengaged from tongues 44a, 46a, and 48a in order to replace panel member 24a. Glazing stop 50a also includes grooves 60 and 62. Panel member 24a is removably and frictionally supported by glazing stop 50a via resilient gaskets 64a and 66a. Resilient gaskets 64a and 66a each have tongues that engage grooves 60 and 62 of glazing stop 50a, respectively. Although not shown in FIGS. 1 and 2, panel member 24a is preferably supported within pivot stile 16a, top rail 20a, and bottom rail 22a using similar structure to glazing stop 50a and resilient gaskets 64a and 66a. As shown in FIG. 2, the center line of panel member 24a is preferably located a distance &#34;a&#34; from a rear surface 90a of door 12. 
     Meeting stile 18b comprises substantially parallel webs 68 and 70 fixedly coupled to parallel webs 72 and 74. Web 70 has tongues 44b, 46b, and 48b on its exterior surface, and web 68 has a region 76 that protrudes toward stile 18a. Meeting stile 18b also comprises a glazing stop 50b. Glazing stop 50b preferably has a substantially identical structure to glazing stop 50a of meeting stile 18a. Glazing stop 50b thus cooperates with resilient gaskets 64b and 66b to removably and frictionally support panel member 24b. Although not shown in FIGS. 1 and 2, panel member 24b is similarly supported within pivot stile 16b, top rail 20b, and bottom rail 22b using similar structure to glazing stop 50b and resilient gaskets 64b and 66b. As shown in FIG. 2, the centerline of panel member 24b is preferably located a distance &#34;a&#34; from a rear surface 90b of door 14. 
     Meeting stile 18b further comprises a sealing member 78 that is movably coupled to region 76 of web 68 via a screw 80 and a hole (not shown) in region 76 for receiving screw 80. A leaf spring 82 biases sealing member 78 away from region 76. Sealing member 78 has a generally convex surface for interfacing with web 38 of meeting stile 18a, and sealing member 78 also has grooves 84 for receiving weather stripping 86. The movement of sealing member 78 along the x-axis toward web 68 is limited by the exterior surface of grooves 84 abutting web 68. As may be appreciated by one skilled in the art, when doors 12 and 14 are closed, sealing member 78 moves along the x-axis so as to create a weather seal between weather stripping 86 and web 38 of meeting stile 18a. 
     Referring now to FIGS. 1, 2, and 4, rear surface 90a of door 12 is preferably planar and is preferably composed of the rear surfaces of pivot stile 16a, top rail 20a, bottom rail 22a, and meeting stile 18a. Similarly, rear surface 90b of door 14 is preferably planar and is preferably composed of the rear surfaces of pivot stile 16b, top rail 20b, bottom rail 22b, and meeting stile 18b. Transom 30 preferably has a weather stripping 79 for interfacing with the top of pivot stile 16a, top rail 20a, meeting stile 18a, meeting stile 18b, top rail 20b, and pivot stile 16b at rear surfaces 90a and 90b. 
     In addition, as shown FIG. 2, when door assembly 10 is closed, rear surfaces 90a and 90b are preferably coplanar with a door jamb line 92. Door jamb line 92 is coplanar with and intersects a line in the y-z plane of jambs 28a and 28b along which pivot stiles 16a and 16b are hinged. 
     Conventional aluminum door assembly 10 is available in a variety of industry standard depths, measured along the z-axis, such as 1.75 inches and 2 inches. In environments subject to high winds, such as those present in a hurricane or similar storm, it is conventional to utilize door assemblies 10 having a 2 inch or greater depth, as the strength and stiffness of door assembly 10 generally increases with increasing depth. However, increasing the depth of door assembly 10 results in a heavier door, substantially increases material and manufacturing costs, and, in some cases, requires a custom frame for supporting the door. Therefore, a need exists in the industry for improved apparatus and methods of increasing the strength and stiffness of aluminum door assembly 10 that are not subject to the above-described limitations. 
     SUMMARY OF THE INVENTION 
     The present invention relates to improved apparatus and methods for increasing the ability of a &#34;double-door&#34; door assembly to withstand stresses caused by high winds and flying debris. More particularly, one aspect of the present invention comprises a door assembly having a first door and a second door. The first door has a pivot stile for pivotally coupling with a first door jam, and a first meeting stile. The second door has a second pivot stile for pivotally coupling with a second door jam, and second meeting stile. The first meeting stile has a greater depth, measured in a plane normal to a plane of the first door, than the remainder of the first door. Similarly, the second meeting stile has a greater depth, measured in a plane normal to a plane of the second door, than the remainder of the second door. 
     In another aspect, the present invention comprises a method of increasing the strength and stiffness of a door assembly. The door assembly includes a first door having a first pivot stile for pivotally coupling with a first door jamb, and a first meeting stile. The door assembly further includes a second door having a second pivot stile for pivotally coupling with a second door jamb, and a second meeting stile. A depth of the first meeting stile, measured in a plane normal to a plane of the first door, is increased relative to a remainder of the first door. Similarly, a depth of the second meeting stile, measured in a plane normal to the plane of the second door, is increased relative to a remainder of the second door. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, and for further objects and advantages thereof, reference is made to the following description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a schematic, front elevational view of a conventional, &#34;double-door&#34; door assembly; 
     FIG. 2 is a cross-sectional view of the conventional door assembly of FIG. 1 along line 2--2; 
     FIG. 3 is a cross-sectional view of a door assembly similar to the conventional door assembly of FIG. 1 along line 2--2 but incorporating modified meeting stiles according to a preferred embodiment of the present invention; and 
     FIG. 4 is a cross-sectional view of the conventional door assembly of FIG. 1 along line 4--4 illustrating a weather seal created along a rear surface of the doors. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention and its advantages are best understood by referring to FIGS. 1-4 of the drawings, like numerals being used for like and corresponding parts of the various drawings. 
     Referring first to FIG. 3, modified meeting stiles 100a and 100b according to a preferred embodiment of the present invention are illustrated. Meeting stiles 100a and 100b replace meeting stiles 18a and 18b, respectively, in conventional aluminum door assembly 10 of FIGS. 1 and 2. Meeting stile 100a comprises substantially parallel webs 102 and 104 fixedly coupled to parallel webs 106 and 108. Web 102 has tongues 44a, 46a, and 48a on its exterior surface for engaging glazing stop 50a, and web 104 has a generally convex geometry for interfacing with meeting stile 100b. Meeting stile 100b comprises substantially parallel webs 110 and 112 fixedly coupled to parallel webs 114 and 116. Web 112 has tongues 44b, 46b, and 48b on its exterior surface for engaging glazing stop 50b, and web 110 has a region 76 for engaging sealing member 78. As may be appreciated from a comparison of FIGS. 2 and 3, glazing stop 50a, resilient gasket 64a, and resilient gasket 66a are preferably identical in meeting stile 100a and in conventional meeting stile 18a. Similarly, glazing stop 50b, resilient gasket 64b, resilient gasket 66b, and sealing member 78 are preferably identical in meeting stile 100b and in conventional meeting stile 18b. 
     Meeting stiles 100a and 100b differ from conventional meeting stiles 18a and 18b in several, critical structural aspects that provide significant advantages. As may be appreciated by one skilled in the art from a comparison of FIGS. 2 and 3, the strength and stiffness of meeting stiles 100a and 100b has been increased from that of conventional meeting stiles 18a and 18b, respectively. As shown in FIG. 3, this increase in strength and stiffness is preferably obtained by increasing the thickness of webs 106 and 108 of meeting stile 100a and of webs 114 and 116 of meeting stile 100b along the z axis in a direction toward the exterior of doors 12 and 14. This increase in the thickness of the webs results in an increase in the overall depth &#34;t 2  &#34; of meeting stiles 100a and 100b, so that &#34;t 2  &#34; is greater than the overall depth &#34;t 1  &#34; of conventional meeting stiles 18a and 18b. However, the only change in the exterior dimensions of meeting stiles 100a and 100b, relative to conventional meeting stiles 18a and 18b, is a protrusion &#34;b&#34; along the front, or exterior, surface of the stiles. Therefore, although the thickness of the webs has been increased, rear surfaces 90a and 90b of doors 12 and 14 at meeting stiles 100a and 100b remain planar with the remainder of rear surfaces 90a and 90b, allowing the weather seal created by weather stripping 79 to remain intact. In addition, the center line of panel members 24a and 24b remains supported a distance &#34;a&#34; from rear surfaces 90a and 90b, respectively, so that the position of panel members 24a and 24b along the z axis in doors 12 and 14 does not change. Furthermore, pivot stiles 16a and 16b, top rails 20a and 20b, and bottom rails 22a and 22b all preferably still have a depth of &#34;t 1  &#34; along the z axis. In short, meeting stiles 100a and 100b may be incorporated into conventional door assembly 10 without any modification to pivot stiles 16a and 16b, top rails 20a and 20b, bottom rails 22a and 22b, glazing stops 50a and 50b, panel members 24a and 24b, or frame 26. 
     As will be understood by one skilled in the art, the strength and stiffness of meeting stiles 100a and 100b may be increased in several alternative, or additional, ways other than increasing the thickness of webs 106 and 108 of meeting stile 100a and of webs 114 and 116 of meeting stile 100b along the z axis in a direction toward the exterior of doors 12 and 14, as shown in FIG. 3. For example, the thickness of webs 106 and 114 may be increased along the z axis in a direction toward the exterior of doors 12 and 14 by a greater amount than shown in FIG. 3. As another example, the thickness of webs 108 and 116 may be increased along the z axis in a direction toward the exterior of doors 12 and 14, or in a direction toward the interior of doors 12 and 14, by a greater amount than shown in FIG. 3. As a further example, the thickness of web 102 may be increased along the x axis in a direction toward meeting stile 100b, and the thickness of web 110 may be increased along the x axis in a direction toward the interior of meeting stile 100b. As a final example, the thickness of web 104 may be increased along the x-axis in a direction toward the interior of meeting stile 100a, and the thickness of web 112 may be increased along the x axis in a direction toward meeting stile 100a. 
     These alternative, or additional, increases in thickness cause no change in the exterior dimensions of meeting stiles 100a and 100b, relative to conventional meeting stiles 18a and 18b, with the possible exception of a lengthening of protrusion &#34;b&#34; along the z-axis in a direction toward the exterior of doors 12 and 14. Of course, these increases in thickness will also increase the weight of doors 12 and 14 at their meeting stiles, and this factor should be taken into account in determining the optimum amount of any such increases in thickness. In addition, as shown in FIG. 3, minimum interior dimensions &#34;l&#34; and &#34;m&#34; may be required in meeting stile 100b due to space constraints imposed by operating hardware such as door locks and lock systems. Such space constraints may impose a practical limit on the amount that the thicknesses of webs 110 and 112 may be increased along the x axis in a direction toward the interior of meeting stile 100b, and on the amount that the thickness of webs 114 and 116 may be increased along the z axis in a direction toward the interior of meeting stile 100b. 
     The following example illustrates the preferred dimensions for meeting stiles 100a and 100b incorporated into a conventional aluminum door assembly 10 having an industry standard depth of 1.75 inches. In such a door assembly 10, pivot rails 16a and 16b, top rails 20a and 20b, and bottom rails 22a and 22b all have about a 1.75 inch depth &#34;t 1  &#34; along the z axis. Meeting stiles 100a and 100b have about a 2.0 inch depth &#34;t 2  &#34; along the z axis. Panel members 24a and 24b have about a 0.25 inch thickness along the z axis, and panel members 24a and 24b are supported within pivot rails 16a and 16b, top rails 20a and 20b, bottom rails 22a and 22b, and meeting stiles 100a and 100b, respectively, so that a centerline of panel members 24a and 24b is located about 0.875 inches from rear surfaces 90a and 90b. Webs 106, 108, 114, and 116 have a general thickness of about 0.25 inches along the z axis. Webs 102, 104, 110, and 112 have a general thickness of about 0.125 inches along the x axis, and protrusion &#34;b&#34; is about 0.25 inches. 
     Having described the structure of door assembly 10, the operation of the door assembly in heavy winds and flying debris associated therewith will now be described in more detail. Referring to FIGS. 1-2, when doors 12 and 14 of conventional door assembly 10 are closed, and a strong wind is blowing against doors 12 and 14 in a direction generally along the z axis, the portions of door assembly 10 most likely to deflect, and possibly cause failure of door assembly 10, are meeting stiles 18a and 18b. This failure mode is most prevalent because pivot stiles 16a and 16b are hinged to jambs 28a and 28b at points 34, and top rails 20a and 20b and bottom rails 22a and 22b have a relatively short length as compared to the length of meeting stiles 18a and 18b. 
     Referring to FIG. 3, by replacing conventional meeting stiles 18a and 18b with the stronger, more stiff meeting stiles 100a and 100b of the present invention, the overall strength and stiffness of door assembly 10 is significantly increased, and the modified door assembly 10 will be able to withstand higher winds. In addition, as the depth of the pivot stiles, the top rails, and the bottom rails of modified door assembly 10 remain the same as in conventional door assembly 10, the weight of door assembly 10 and the material and manufacturing costs of door assembly 10 are not substantially increased. Furthermore, these advantages may be obtained with only minimal structural modifications to an industry standard door assembly and an industry standard frame. Significantly, meeting stiles 100a and 100b can be incorporated into a conventional door assembly 10 without any modifications to pivot stiles 16a and 16b, top rails 20a and 20b, bottom rails 22a and 22b, glazing stops 50a and 50b, panel members 24a and 24b, or frame 26. 
     The present invention is illustrated herein by example, and various modifications may be made by a person of ordinary skill in the art. For example, numerous geometries and/or relative dimensions could be altered to accommodate specific applications of the modified meeting stiles of the present invention in a variety of door assemblies. As another example, although the present invention has been described in connection with aluminum door assemblies, it is equally applicable to fire rated door assemblies and door assemblies made from other conventional building materials, such as metals other than aluminum, wood, plastics, or composite materials. 
     It is thus believed that the operation and construction of the present invention will be apparent from the foregoing description. While the method and apparatus shown or described have been characterized as being preferred it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the following claims.