Patent Publication Number: US-6711860-B2

Title: Construction panel interconnection system

Description:
FIELD OF THE INVENTION 
     The present invention relates to the fields of residential or commercial structures, and models, toys, and play equipment. More specifically, it relates to the interconnection of panels for modular structures. 
     BACKGROUND OF THE INVENTION 
     The building industry today is dominated by conventional designs and construction practices. Conventional building techniques are very time-consuming, generally requiring a substantial amount of field labor. Moreover, mobilizing fabrication resources to the field is expensive. Conventional construction is also dominated by volumetric spaces bounded by rectangular or mixed rectangular-trapezoidal shapes. 
     Departures from conventional designs such as the “habitat” presented at the 1967 Montreal Expo, or a more geometrically sophisticated modular construction system as disclosed in U.S. Pat. No. 6,173,538 entitled “Modular Construction System” issued to Fleishman, which patent is hereby incorporated by reference as if fully set forth herein, attempts to simplify building construction while providing versatility and functionality. These modular construction designs often make use of standardized prefabricated units, commonly planar in configuration as to be used for walls, baseboards or ceilings, to simplify construction. Some modular designs call for interconnecting two planar units, while others call for interconnecting three planar units. 
     Construction using these standardized, prefabricated units or panels, however, continues to suffer from substantial limitations. Commonly, interconnecting these prefabricated units require the cumbersome step of aligning the long edges of the panels or walls, temporality holding them in place, and permanently securing the panels together using braces, screws, bolts or other fastening devices. Other times, a separate interconnecting part, providing grooves for the panels to fit into, is used to interconnect the prefabricated units. However, using these separate interconnecting parts still require more parts than the panels being interconnected and adds to the inventory of parts needed for a construction project. For a modular structure requiring interconnection of three panels, the assembly is even more cumbersome and costly as greater labor and number of parts are needed. 
     Accordingly, with the growing sophistication in modular design, there is a need for an improved assembly and method for joining or interconnecting two or three prefabricated units simply and effectively. 
     SUMMARY OF THE INVENTION 
     In a first separate aspect of the present invention, a system for interconnecting panels includes a hybrid connector, receptor connector, and locking connector. The hybrid connector has a tab that mates with an aperture of the receptor connector. The locking connector has a tab that mates with an aperture of the hybrid connector. As the connectors may be adapted to panels, mating the connectors interconnects the panels. 
     In a second separate aspect of the invention, the system for interconnecting panels of the first aspect of the invention further includes an extension tab lying orthogonal to the tab of the hybrid connector and/or the locking connector. The extension tab engages with the aperture of the corresponding connector so as to provide an additional locking action for interconnecting panels having panel connectors. 
     In a third separate aspect of the invention, a system for interconnecting panels includes hybrid, receptor and locking connectors having stiffening portions. The stiffening portions form interfitting profiles that fill the spaces between the three connectors which advantageously reduces the need to insulate the interconnection, assists in repelling foreign matter entry, and resists relative panel connector rotation where panel rotation is not needed during panel interconnection. 
     In a fourth separate aspect of the invention, a modular construction system includes panels having hybrid, receptor or locking connectors. The panels are interconnected such that a modular construction can be erected without the use of fastening devices. 
     In a fifth separate aspect of the present invention, a method for interconnecting panels for modular construction includes selecting panels having panel connectors, mating the hybrid connector to the receptor connector, and then mating the locking connector to the hybrid connector/receptor connector sub-assembly to interconnect the connectors attached to panels. 
     A sixth separate aspect of the present invention includes the combination of the foregoing aspects. 
     Other advantages will appear. The invention resides not only in the interconnection systems and methods to interconnect, but also in the construction of structures described and illustrated. The features shown with one embodiment may also be used with other embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a modular construction structure. 
     FIG. 2 is a perspective view of an assembled three-panel interconnection. 
     FIG. 3 is an exploded perspective view of the three-panel interconnection of FIG.  2 . 
     FIG. 4 is a front view of a panel including a hybrid connector. 
     FIG. 5 is an expanded front view of a hybrid connector element of the hybrid connector of FIG.  4 . 
     FIG. 6 is a front view of a panel including a receptor connector. 
     FIG. 7A is an expanded front view of a receptor element of the receptor connector of FIG.  6 . 
     FIG. 7B is an end view of the receptor element of FIG.  7 A. 
     FIG. 8 is a front view of a panel including a locking connector. 
     FIG. 9A is an expanded front view of a locking element of the locking connector of FIG.  8 . 
     FIG. 9B is an expanded front view of a locking element having a base edge offset from the panel perimeter. 
     FIG. 10A is a perspective view of a first panel having a hybrid connector mated with a second panel having a receptor connector. 
     FIG. 10B is a perspective view of a third panel having a locking connector mated with the first and second panels of FIG.  10 A. 
     FIG. 10C is a cross sectional view of a third panel having a locking connector mated with the first and second panels of FIG.  10 A. 
     FIG. 11A is a cross sectional view of a three-panel interconnection. 
     FIG. 11B is a cross sectional view of a three-panel interconnection, wherein the hybrid connector has an enlarged aperture. 
     FIG. 11C is a cross sectional view of a three-panel interconnection, wherein the receptor connector has an enlarged aperture. 
     FIG. 12 is a cross sectional view of a three-panel interconnection, wherein the inner profile of the receptor aperture has a beveled edge. 
     FIG. 13A is a plan view of a stand-alone hybrid connector. 
     FIG. 13B is a plan view of a stand-alone receptor connector. 
     FIG. 13C is a plan view of a stand-alone locking connector. 
     FIG. 14 is a perspective view of an assembled two-panel interconnection utilizing a stand-alone locking connector. 
     FIG. 15A is a plan view of an enhanced hybrid connector element. 
     FIG. 15B is a plan view of an alternate enhanced hybrid connector element configuration. 
     FIG. 15C is a plan view of an enhanced locking element. 
     FIG. 15D is a plan view of an alternate enhanced locking element configuration. 
     FIG. 16A is a cross-sectional view of a connection wherein an enhanced locking element is mated with the hybrid connector/receptor connector sub-assembly prior to engaging. 
     FIG. 16B is a cross-sectional view of the connection of FIG. 16A, wherein the enhanced locking element is engaged with the hybrid connector protruding tab. 
     FIG. 17A is a view of an enhanced locking element having a tapered configuration. 
     FIG. 17B is a schematic view of an enhanced locking element having a contoured configuration. 
     FIG. 18A is a schematic perspective view of an assembled three-panel interconnection of stiffened panel connectors. 
     FIG. 18B is an exploded perspective view of the three-panel interconnection of FIG.  18 A. 
     FIG. 19 is a cross sectional view of a stiffened hybrid connector. 
     FIG. 20 is a cross sectional view of a stiffened receptor connector. 
     FIG. 21 is a cross sectional view of a stiffened locking connector. 
     FIG. 22 is a cross sectional view of a three-panel interconnection of stiffened panel connectors having asymmetrical stiffeners. 
     FIG. 23 is a cross sectional view of panels with stiffeners having an alternate intermitting profile configuration. 
     FIG. 24 is an exploded perspective view of a modular structure. 
     FIG. 25A is a plan view of a first construction panel having an artistic impression. 
     FIG. 25B is a plan view of a second construction panel having an alternate artistic impression. 
     FIG. 26 is a cross sectional view of a three-panel interconnection of panel connectors adapted to thicker panels. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Turning now in detail to the drawings, a system for interconnecting modular construction panels is disclosed. FIG. 1 shows a representative modular structure  10  comprising of a collection of modules  11 , where each module  11  includes an interconnection of panels  12  by employing two-panel interconnections  14  and three-panel interconnections  16  according to the present invention to assemble the modular structure  10 . 
     FIG. 2 shows an enlarged view of an assembled three-panel interconnection  16  according to the present invention. Referring to FIG. 3, an exploded view of the three-panel interconnection  16  shows more clearly a first embodiment of the present invention comprising a first panel  18  that includes a hybrid connector  20 , where the hybrid connector  20  has hybrid connector element  22 ; a second panel  24  that includes a receptor connector  26 , where the receptor connector  26  has a receptor element  28 ; and a third panel  30  that includes a locking connector  32 , where the locking connector  32  has a locking element  34 . 
     Throughout the specification, the hybrid connector  20 , receptor connector  26 , and locking connector  32  will generally and collectively be referred to as “panel connectors.” Panel connectors may or may not be adapted to a construction panel. Panel connectors adapted to a segment and not to a panel, as will be described in more detail below, will generally and collectively be referred to as “stand-alone panel connectors.” Finally, a hybrid connector element  22 , receptor element  28  and locking element  34 , as will be described in more detail below, will generally and collectively be referred to as “connector elements.” 
     Referring to FIG. 4, a front view of the first panel  18  shows a hybrid connector  20  adapted to the panel along a panel perimeter. The hybrid connector  20  includes at least one hybrid connector element  22 . In the arrangement shown, the hybrid connector  20  has two hybrid connector elements  22 . 
     FIG. 5 is an expanded view of an exemplary hybrid connector element  22 . The hybrid connector element  22  has a base edge  36 , a protruding tab  38  and an aperture  40 . The protruding tab  38  is preferably rectangular in shape, having an outer edge  42  and side edges  44 . The outer edge  42  is substantially parallel to and offset from the base edge  36 . The side edges  44  are substantially orthogonal to the base edge  36 . 
     A hybrid connector aperture  40  is defined within the protruding tab  38 . The aperture  40  is preferably rectangular in shape, having long edges  46  and short edges  48 . The long edges  46  are substantially parallel to and offset from the base edge  36 . The short edges  48  are substantially orthogonal to the base edge  36 . 
     Referring to FIG. 6, a front view of the second panel  24  shows two receptor connectors  26  adapted to opposing perimeters on the second panel. The receptor connector  26  includes at least one receptor element  28 . In the arrangement shown, each receptor connector  26  has two receptor elements  28 . 
     FIG. 7A shows an expanded front view and FIG. 7B shows the end view of a receptor element  28 . The receptor element  28  as shown has a base edge  50 , an aperture  52 , a first side  54  and a second side  56 . The receptor aperture  52  is preferably rectangular in shape and includes long edges  58  and short edges  60 . The long edges  58  are substantially parallel to and offset from the base edge  50 . The short edges  60  are substantially orthogonal to the base edge  50 . The receptor aperture  52  is sized such that the hybrid connector protruding tab  38  can be inserted into the receptor aperture  52  from the first side  54 , and fit sufficiently through the receptor aperture  52  such that the hybrid connector aperture  40  is accessible from the second side  56  of the receptor connector  26 . 
     Referring to FIG. 8, a front view of the third panel  30  shows the locking connector  32  adapted to a perimeter of the third panel  30 . The locking connector  32  includes at least one locking element  34 . In the arrangement shown, the locking connector  32  has two locking elements  34 . 
     FIG. 9A shows an expanded view of a locking element  34 . The locking element  34  has a base edge  62  and a protruding tab  64 . The protruding tab  64  is preferably rectangular in shape, having an outer edge  66  and side edges  68 . The outer edge  66  is substantially parallel to and offset from the base edge  62 . The side edges  68  are substantially orthogonal to the base edge  62 . The protruding tab  64  of the locking connector  32  is sized such that it may fit sufficiently into and through the hybrid connector aperture  40 . 
     In a first method of interconnecting the three panels, the first panel  18  having the hybrid connector  20  is mated with the second panel  24  having the receptor connector  26  by inserting the hybrid connector protruding tab  38  into the receptor aperture  52  as shown in FIG.  10 A. To properly mate, the hybrid connector protruding tab entering from the first side  54  of the receptor connector  26  must be positioned through receptor aperture  52  such that the hybrid connector aperture  40  is accessible from the second side  56  of the receptor connector  26 . Referring now to FIGS. 10B and 11A, the third panel  30  having the locking connector  32  is then mated with the first panel/second panel sub-assembly by inserting the locking protruding tab  64  into the hybrid aperture  40  from the second side  56  of the receptor connector  26 , thereby interconnecting the three panels. 
     In a second method of interconnecting the three panels, the first panel  18  is mated with the second panel  24  as described above and shown in FIG.  10 A. However, the hybrid connector protruding tab entering from the first side  54  of the receptor connector  26  is positioned such that the hybrid connector aperture  40  is accessible from the first side  54 . FIG. 10C illustrates a cross sectional view of an interconnection according to the second method where the third panel  30  having the locking connector  32  is then mated with the first panel/second panel sub-assembly by inserting the locking protruding tab  64  into the hybrid aperture  40  from the first side  54  of the receptor  26 , thereby interconnecting the three panels. 
     Each panel connector described thus far have included two connector elements. However, a panel connector may have less or more connector elements for interconnecting purposes to accommodate small or large panels, or to achieve the desired panel interconnection stiffness. Additionally, though the connector elements are illustrated having a simple rectangular configuration, any shape suitable for mating as described above may be employed to practice the present invention. For example, as would be evident to those skilled in the art, an elliptical or oval shaped tab or aperture may be used to practice the invention. The simple rectangular configuration, however, advantageously reduces the cost to manufacture while effectively practicing the present invention. 
     Moreover, though the base edge  36 ,  50 ,  62  of the connector elements are shown lying common to the perimeter edge of the panels, a base edge may lie separately from the perimeter edge. For example, as illustrated in FIG. 9B, the base edge  62  of the locking element  34  may be offset from the perimeter edge  63  of the third panel  30 . Finally, a panel may have any combination of panel connector types adapted to its perimeters to practice the invention. 
     FIG. 11A illustrates a cross sectional view of an interconnection of a first panel  18  having a hybrid connector  20 ; a second panel  24  having a receptor connector  26 ; and a third panel  30  having a locking connector  32 . The angular orientation between the first panel  18  and third panel  30  is approximately 90°. The angular orientation between the second panel  24  and the first panel  18 , and between second panel  24  and the third panel  30 , is approximately 135°. The relative angular orientation between the three panels, however, may be varied by adjusting the size of the hybrid connector aperture short edge  48  and/or the receptor aperture short edge  60 , relative to the thickness of the hybrid connector protruding tab  38  and locking tab  64 . 
     For example, a system of panels may have a hybrid element and locking element protruding tab thickness of T. Where the short edge  48  of the hybrid connector aperture  40  is T, plus a small amount for clearance, the angular orientation between the first and third panel when mated is approximately 90° as shown in FIG.  11 A. To increase the range of angular orientation between the first and third panels, the hybrid connector aperture short edge  48  may be increased. As shown in FIG. 11B, increasing the short edge  48  permits the possible angular orientation between the first and third panel to a value greater than 90°. 
     Similarly, the angular position of the first and third panels relative to the second panel  24  can be varied by adjusting the short edge  60  of the receptor aperture  52 . Referring to FIG. 11A, a receptor aperture short edge value of 2.414 times T provides a symmetrical 135° orientation about the second panel. To increase the range of angular orientation, the short edge  60  may be increased. As shown in FIG. 11C, increasing the short edge  60  increases the possible angular orientation between the second and first panel, or between the second and third panel, to a value greater than 135°. As would be evident to those skilled in the art, increasing the size of both aperture short edges will provide even greater angular orientation range. 
     Referring now to FIG. 12, adding a bevel edge  61  to the inner profile of the aperture  52  can advantageously reduce the short edge value needed to acquire the same angular orientation. For example, by providing a bevel 0.207 times T along the internal edge of the receptor aperture  52 , the short edge  60  of the receptor aperture  52  can be reduced to 2 times T while still providing the symmetrical 135° orientation about the second panel  24 . Adding the bevel edge improves the durability of the inner profile by removing the sharp edge corner. Also, by reducing the short edge  60 , less material is removed from the receptor connector element  28  and, consequently, the stiffness and strength of the connector element is better retained. 
     With the configuration as above described, three panels may be interconnected without the use of fastening hardware or separate interconnecting devices. Additionally with the configuration as above described, the range of relative panel angles may be achieved by selectively sizing one or both short edges of the connector apertures. Furthermore, where either or both of receptor connector aperture  52  or hybrid connector aperture  40  is enlarged, clearance is provided where either the hybrid connector element  22  or the locking connector element  34  can be inserted into the corresponding aperture and then be rotated into place. This rotational flexibility advantageously assists during the panel interconnection process, especially where space is limited. 
     Moreover, where interconnection of two panels is desired, a stand-alone panel connector, i.e. a panel connector that is not adapted to a panel or other construction units, may be used. FIGS. 13A,  13 B and  13 C illustrate stand-alone hybrid connector  72 , stand-alone receptor connector  74 , and stand-alone locking connector  76 , respectively. FIG. 14 illustrates a two-panel interconnection comprising a first panel  18  including a hybrid connector  20 , a second panel  24  including a receptor connector  26 , and stand-alone locking connector  76 . 
     A second embodiment of the present invention comprises a system for interconnecting panels of the first embodiment including an enhanced hybrid connector  21 , and/or an enhanced locking connector  77  in place of the standard hybrid connector  20  and/or the standard locking connector  32 . 
     The enhanced hybrid connector  21  includes an enhanced hybrid connector element  23  as shown in FIG.  15 A. The enhanced hybrid connector element  23  has a base edge  25 , protruding tab  27 , aperture  29  and an extension tab  31 . The protruding tab  27  and extension tab  31  are preferably rectangular in shape. The protruding tab  27  protrudes from the base edge  25  and includes an outer edge  33  and side edges  35 . The outer edge  33  is substantially parallel to and offset from the base edge  25 . The side edges  35  are substantially orthogonal to the base edge  25 . The extension tab  31  extends from the protruding tab  27  substantially parallel to and offset from the base edge  25 . 
     Similarly, the enhanced locking connector  77  includes an enhanced locking element  78  as shown in FIG.  15 C. The enhanced locking element  78  has a base edge  80 , protruding tab  82  and an extension tab  84 . The protruding tab  82  and extension tab  84  are preferably rectangular in shape. The protruding tab  82  protrudes from the base edge  80  and includes an outer edge  86  and side edges  88 . The outer edge  86  is substantially parallel to and offset from the base edge  80 . The side edges  88  are substantially orthogonal to the base edge  80 . The extension tab  84  extends from the protruding tab  82  substantially parallel to and offset from the base edge  80 . 
     The system for interconnecting panels according to the second embodiment comprises of a set of panel connectors that may include both enhanced hybrid connector and enhanced locking connector, or only one of the enhanced connectors in place of the standard panel connectors. To illustrate, an interconnection of panels utilizing a standard receptor connector  26 , a standard hybrid connector  20 , and an enhanced locking connector  77  will now be described. The mating of the hybrid connector with the receptor connector is as previously described for the first embodiment. The enhanced locking connector  77  then mates with the hybrid connector/receptor connector sub-assembly by orienting the protruding tab  82  and extension tab  84  into and through the hybrid connector aperture  40  such that the extension tab  84  is beyond the thickness of the hybrid connector protruding tab  38  as shown in FIG.  16 A. The enhanced locking connector  77  is then laterally displaced such that the extension tab  84  engages with the hybrid connector protruding tab  38  as shown in FIG.  16 B. With the configuration as described, engaging the extension tab  84  provides an additional locking action between the hybrid connector  20  and the locking connector  77  for interconnecting the panel connectors. 
     Where an enhanced hybrid connector  21  is used, the extension tab  31  is engaged to the receptor connector  26  in the same manner as described above for engaging the extension tab  84  of the enhanced locking tab  77  to the hybrid connector  20 . 
     Referring to FIG. 15A, the enhanced hybrid connector element  23  shown has the extension tab edge farthest from its base edge  25  sharing a common edge with the outer edge  33  of the enhanced hybrid connector protruding tab  27 . Similarly, referring to FIG. 15C, the enhanced locking element  78  shown has the extension tab edge farthest from the base edge  80  sharing a common edge with the outer edge  86  of the locking connector protruding tab  82 . The extension tabs  31 ,  84  are also shown being rectangular and co-planar with the protruding tab of the connector element. The additional locking action capability of the enhanced panel connector however is not limited to a single co-planar, orthogonal, rectangular extension tab. Although a single extension tab  31 ,  84  has been disclosed, the enhanced connector elements  23 ,  78  may have multiple extension tabs as shown in FIGS. 15B and 15D. Also, while a simple rectangular extension tab advantageously reduces the cost to manufacture, a tapered extension tab as shown in FIG. 17A or a contoured tab as shown in FIG. 17B, shown only in the context of an enhanced locking element but also applicable to enhanced hybrid element, can provide the locking action between the enhanced panel connector and the corresponding connector. Similarly, as would be recognized by those skilled in the art, the extension tab thickness is governed by the design strength, and may be thinner or thicker than the protruding tab. 
     FIG. 18A illustrates an assembled view of a third separate embodiment of a system for interconnecting panels that includes a stiffened hybrid connector  90 , stiffened receptor connector  92  and stiffened locking connector  94 . FIG. 18B is an exploded view of the stiffened panel connector system of FIG.  18 A. 
     A stiffened hybrid connector  90  includes a hybrid connector element  22 , and a hybrid stiffener  96  as seen in FIG.  19 . The hybrid connector element  22  has a base edge  36 , a protruding tab  38 , and an aperture  40  as previously disclosed above. Here, the hybrid stiffener  96  is arranged on both sides of the hybrid connector element  22  and includes a first and second interfitting profiles  98 ,  100  for fitting into corresponding profiles of the stiffened receptor connector  92 . 
     The stiffened receptor connector  92  includes a receptor connector element  28 , a receptor stiffener  102 , and spline  104  as seen in FIG.  20 . The receptor connector element  28  includes a base edge  50  and an aperture  52  as previously discussed. Here, the receptor stiffener  102  is arranged on both sides of the receptor connector element  28  and includes third and fourth interfitting profiles  106 ,  108 . The spline  104  positioned centrally and attached to the base edge  50  includes fifth and sixth interfitting profiles  110  and  112  as shown in FIG.  20 . In the arrangement illustrated in FIG. 20, the first and second interfitting profiles  98  and  100  of the stiffened hybrid connector  90  fits with the third and fifth interfitting profiles  106  and  110 . The fourth and sixth interfitting profiles  108  and  112  of the stiffened receptor connector  92  fit into corresponding profiles of the stiffened locking connector  94 . 
     The stiffened locking connector  94  includes a locking connector element  34  and a locking stiffener  114  as seen in FIG.  21 . The locking connector element  34  has a base edge  62  and a protruding tab  64  as previously disclosed above. Here, the locking stiffener  114  is arranged on both sides of the locking connector element  34  and includes a seventh and eighth interfitting profiles  116 ,  118  for fitting into corresponding fourth and sixth interfitting profiles  108 ,  112  of the stiffened receptor connector  92 . 
     Referring again to FIG. 18A the stiffened panel connectors are shown interconnected according to the present invention. The mating sequence is as previously disclosed. The stiffened hybrid connector  90  is mated with the stiffened receptor connector  92  such that the hybrid connector aperture  40  is accessible from the second side of the receptor element. This first mating step also fits the first and second interfitting profiles  98 ,  100  with the third and fifth interfitting profiles  106 ,  110 . The stiffened locking connector  94  is then mated with the sub-assembly by inserting the locking tab  64  into the hybrid connector aperture  40 . This second mating step also fits the seventh and eighth interfitting profiles  116 ,  118  with the fourth and sixth interfitting profiles  108 ,  112 . As illustrated in FIG. 18A, once mated, the panel connector elements interconnect the stiffened panel connectors together and the interfitted profiles fill the spaces between the panel connectors. The space filling feature of the interfitted profiles advantageously reduces the need to insulate the interconnection, assists in repelling foreign matter from crossing from one side of the panel to another, and resists relative panel connector rotation where rotation is not needed during panel interconnection. 
     The panel stiffener may be integrally cast or formed with the connector element or machined from common stock as will be evident to those skilled in the art. Alternatively, the panel stiffener may be a separate layer of material secured to the connector element by adhesive or standard fasteners known in the art such as, for example, nails, screws, or staples. The stiffened locking connector  94  may also be comprised of an enhanced locking element  76  in place of the standard locking element  34 . The assembly of the stiffened locking connector  94  having the enhanced locking connector  76  is according to the sequence as previously described. 
     Furthermore, though the preferred stiffener portions  96 ,  102 ,  114  shown has the connector element centrally located about two interfitting profiles, a single interfitting profile may be provided on one side of the connector element as shown in FIG.  22  and still provide effective insulation or resistance to contamination at the interconnection. Also, though the preferred interfitting profile is bevel-shaped as shown in FIGS. 18A and 18B, those skilled in the art will recognize other matching interfitting shapes, such as an orthogonal slot and groove as shown in FIG. 23, may be used. The simple bevel shape, however, advantageously reduces the cost of manufacture while effectively practicing the present invention. 
     A modular structure in accordance with the present invention will now be disclosed. A representative fully assembled module  119 , which may itself be deemed a modular structure, is illustrated in FIG.  1 . FIG. 24 is an exploded view of the modular structure  119  that includes a bottom panel  120 , side panels  122 ,  124 ,  126 ,  128 , top panel  130 , and expansion panel  132 . Though not every perimeter needs to have a panel connector, where an interconnection is to be made, a panel connector must be provided. 
     The construction of the modular structure of FIG. 24 will now be described. The bottom panel  120  may be configured with a hybrid connector  20  such as shown in FIG. 4 on every perimeter. A first side panel  122  is selected having a locking connector  32  such as shown in FIG. 8 along the panel edge that is to interconnect with the bottom panel  120 . The first side panel  122  is then interconnected to the bottom panel  120  using a stand-alone receptor connector (not shown) according to the present invention already discussed. It should be noted that the panel connectors adapted to the bottom panel, side panel and standing connector are arbitrary. This first interconnection may easily be accomplished by alternatively using a bottom panel having a receptor connector, a side panel having a locking connector and a stand-alone hybrid connector. 
     Next, a second side panel  124  is selected having suitable panel connector to interconnect to the first side panel  122  and the bottom panel  120 . As these interconnections are two-panel interconnections, an appropriate stand-alone connector may be used. Hence, by selecting panels with appropriate connectors and systematically interconnecting panels as described above, a modular structure may be assembled. Note that in circumstances where relative panel displacement is unlikely, a stand-alone connector may not be necessary to provide a secure two-panel interconnection. For example, in circumstances where a side panel having an enhanced locking connector is interconnected to a side panel having a hybrid connector, use of a stand-alone receptor connector may not be needed if the extension tab engagement may be sufficient to secure the two panels in place. 
     Interconnection of separate modular structures can be accomplished by employing a three-panel interconnection. Referring again to FIGS. 1 and 24, the three-panel interconnection of panels  124 ,  126  and  132  provides panel  132  as a starting panel for a second module  121  that is interconnected to the first module  119 . 
     Although rectangular panels have been illustrated to describe the details of the present invention, those skilled in the art will recognize that the panel interconnection system of the present invention is not limited to a particular panel geometry. The panel connectors of the present invention may be adapted to any panel shape such as, but not limited to rhombuses, trapezoids, parallelograms, circles, triangles or hexagons. Hence, with the myriad of panel shapes that are available in addition to the various angular orientation the panel connectors can accommodate, the present invention provides the capacity to construct complex space filling geometries. 
     Additionally, the panel may have cutouts for windows, doors, screens or other functional qualities, such as the rounded cutout  133  shown in FIG.  24 . Also, the panels may have artistic impressions, patterns or other aesthetic qualities as shown in FIGS. 25A and 25B. Furthermore, the panel thickness may vary from the connector elements. For example, as shown in FIG. 26, panels adapted to the connector elements may be thickened with insulation or other materials. 
     The embodiments disclosed according to the present invention are applicable for various purposes. As directed to play equipment, toys or models, the stiffened and non-stiffened panel connectors may be fabricated from durable plastic, wood or other suitable materials or combination of materials known in the art. As directed to habitable or commercial structures, the panel connector may be cast or machined metal, wood, plastic composites or a combination of these or similarly available materials known in the art. In either application, the panel connector may be a free standing unit, integral to a panel or separable and attached to the panel by adhesive or other securing means known in the art. 
     The panel to which the panel connector of the present invention may be adapted or attached, may be composed of a single layer made of wood, drywall, plastic, composite, or other material suitable for construction purposes. The panel may also be composed of multiple layers of materials such as wood, insulation, drywall, plastic, composite, or any combination of these or other suitable materials known in the art. 
     Thus, novel panel interconnection systems and methods, and structures comprising the system have been shown and described. Various modifications may, of course, be made, without departing from the spirit and scope of the invention. The invention, therefore, should not be limited, except by the following claims and their equivalents.