A portable toilet shelter that is more stackable and easier to assemble and disassemble. The portable toilet shelter includes a loop enclosure that is mountable to a base, and that is adapted to receive a roof. The loop enclosure includes opposed end walls each having opposed edges. Opposed side walls are positioned between the opposed end walls, with each of the side walls also having opposed edges. Flexible hinges connect the edges of the side walls to respective adjacent edges of the end walls to complete the loop enclosure. The portable toilet shelter is partially disassembled when collapsed to a height of about the thickness of two walls, wherein the end walls fold respectively toward and overlay the side walls. The portable toilet shelter is partially erected when the end walls are unfolded respectively away from the side walls to maintain an upright and self-supporting position.

CROSS-REFERENCES TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         REFERENCE TO A MICROFICHE APPENDIX  
         [0003]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    The present invention generally relates to portable building structures. More specifically, this invention is directed to a collapsible and stackable portable toilet shelter that is easier to fold flatter, transport, and assemble than prior art toilet shelters, such that assembly time and shipping costs are reduced.  
           [0006]    2. Description of the Related Art  
           [0007]    Portable toilet shelters are widely used throughout the world for various uses such as at construction sites, festivals, and other point of use having large gatherings of people. Portable toilet shelters are shipped from a provider to a point of use in many ways including as fully assembled in one piece, completely disassembled into individual components, or partially assembled.  
           [0008]    First, there are disadvantages with shipping a fully assembled portable toilet shelter. Very few such units can be transported at a time. For example, a bed of a pickup truck will accommodate only two fully assembled units. Such a small payload of units is not cost effective to ship to a customer.  
           [0009]    Second, many prior art portable toilet shelters are shipped in a completely disassembled state. Unfortunately, this is also a problem since it takes such a long time to assemble each unit, and often requires two people to assemble each unit, resulting in excessive labor cost. For example, it can take up to an hour for two people to assemble just one completely disassembled unit. This is a particularly significant problem for deliveries of dozens of units that require many hours of labor for assembly and disassembly. Such a labor-intensive solution to the fully assembled shelter is not cost effective for shipping toilet shelters to a customer.  
           [0010]    Another approach is to ship the portable toilet shelters in sub-assembly form. This approach is taught by U.S. Pat. No. 4,493,118 to Braxton, the inventor hereof. Braxton discloses a collapsible portable toilet shelter having a base member, a roof panel, and a foldably collapsible rectangular enclosure therebetween. Basically, the toilet shelter is assembled by placing the base member on a surface, unfolding the rectangular enclosure, fitting the bottom of the rectangular enclosure to the base member, placing the roof panel to the top of the rectangular enclosure, and fastening the parts of the toilet shelter together. Uniquely, the rectangular enclosure includes a front wall, a back wall, and bi-fold side walls. Each bi-fold side wall is composed of forward and rearward panels connected by continuous hinge members. The rectangular enclosure collapses when the side panels are swung inwardly such that the forward and rearward panels fold toward each other so that the front wall and back wall collapse together toward one another. Therefore, the Braxton '118 solution provides a portable toilet shelter that assembles and disassembles easily and that can be shipped cost effectively to a customer.  
           [0011]    One drawback with the Braxton '118 solution, however, is that the stacking and assembly of each portable toilet shelter is not optimized. The rectangular enclosure folds so that the front and back walls are parallel, or are aligned, with one another. Thus, the rectangular enclosure necessarily collapses to a stack height equal to at least four times the thickness of a wall, counting the front wall, forward and rearward panels of each side wall, and the back wall. Whether the units are transported in a vertical stack or a horizontal stack, the more each unit can be collapsed, the more units can be shipped on the same size truck to save on shipping costs. Similarly, the easier it is to assemble each unit, the less labor hours are required to save on labor costs. Ultimately, a more efficient portable toilet design would translate into cost savings and convenience to the public.  
           [0012]    From the above, it can be appreciated that portable toilet shelters of the prior art are not fully optimized to improve the stackability and assembly characteristics thereof and thereby reduce the costs associated therewith. Therefore, what is needed is a more efficiently stackable, less costly to transport, and easier to assemble portable toilet shelter.  
         BRIEF SUMMARY OF THE INVENTION  
         [0013]    According to the preferred embodiment of the present invention, there is provided a portable toilet shelter having a loop enclosure that is mountable to a base, and adapted to receive a roof. The loop enclosure includes opposed end walls each having opposed edges, and further includes opposed side walls positioned between the opposed end walls with each of the side walls having opposed edges. The loop enclosure also includes flexible hinges for connecting the edges of the side walls to respective adjacent edges of the end walls such that the end walls and side walls complete the loop enclosure.  
           [0014]    The portable toilet shelter is partially disassembled when the roof is removed, the loop enclosure is lifted away from the base, and the loop enclosure is collapsed wherein the end walls fold respectively toward the side walls, such that each of the end walls overlays a respective one of the side walls. Accordingly, the overall height of the collapsed portable toilet shelter is roughly equivalent to the thickness of two walls. Conversely, the portable toilet shelter is partially erected when the end walls are unfolded respectively away from the side walls. In this position, the walls are unfolded to position the side walls substantially parallel to one another and the end walls substantially parallel to one another, wherein the side walls are substantially respectively transverse to the end walls to form an enclosure. Accordingly, the loop enclosure is unfoldable to be capable of maintaining an upright and self-supporting position. Thus, the present invention is capable of providing a portable toilet shelter that is more compact, more stackable, and easier to assemble and disassemble than any prior art shelter, and is therefore more cost effective.  
           [0015]    It is an object of the present invention to provide a more stackable toilet shelter compared to those of the prior art. Approximately 150 portable toilet shelters of the present invention can be shipped on an standard 53 foot long semi-truck trailer, which is eight times the number of fully assembled shelters and two times the number of foldable prior art shelters that can be shipped on the same size truck trailer.  
           [0016]    It is another object that the present invention is capable of disassembly by one person and is easier to assemble and disassemble than prior art collapsible toilet shelters. Fully disassembled prior art toilet shelters require about a half an hour to assemble and disassemble, and the folding prior art shelters require about ten minutes to assemble and disassemble. In contrast, the portable toilet shelter of the present invention requires only about five minutes to assemble and disassemble by one person.  
           [0017]    It is still another object that the present invention will save on shipping costs and labor costs due to the improved stackability and assembly of the portable toilet shelter.  
           [0018]    These objects and other features, aspects, and advantages of this invention will be more apparent after a reading of the following detailed description, appended claims, and accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a perspective view of the portable toilet shelter according to the preferred embodiment of the present invention;  
         [0020]    [0020]FIG. 2 is an enlarged view of a corner of the portable toilet shelter of FIG. 1;  
         [0021]    [0021]FIG. 3 is a partially cutaway perspective view of the portable toilet shelter of FIG. 1;  
         [0022]    [0022]FIG. 4 is an enlarged perspective view of a support as used in the portable toilet shelter of FIG. 3;  
         [0023]    [0023]FIG. 5 is a perspective view of a toilet unit as used in the portable toilet shelter of FIG. 3;  
         [0024]    [0024]FIG. 6 is a partially cutaway perspective view of a portable toilet shelter according to an alternative embodiment of the present invention;  
         [0025]    [0025]FIG. 7 is a top view of the portable toilet shelter according to the preferred embodiment, not showing the toilet unit;  
         [0026]    [0026]FIG. 8 is a top view of a loop enclosure of the portable toilet shelter of FIG. 1, wherein the loop enclosure is being collapsed;  
         [0027]    [0027]FIG. 9 is a top view of the loop enclosure of FIG. 8 as fully collapsed; and  
         [0028]    [0028]FIG. 9A is a top view of a loop enclosure of the portable toilet shelter of FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    Referring now in detail to the Figures, there is shown in FIG. 1 a portable toilet shelter  10  that is constructed in accordance with the present invention. Uniquely, the portable toilet shelter is hinged along each of its four corners  12  with flexible hinge strips  14 . Preferably, as shown in FIG. 2, the flexible hinge strips  14  are fastened to the portable toilet shelter  10  with rivets  16 , but may also be integrally fastened thereto using any other method including thermoforming or heat lamination techniques. The novel and unobvious aspects of the present invention apply not only to toilet shelters, but also apply to any other types of portable shelters. Other types of portable shelters include but are not limited to changing rooms, hand wash stations, first aid buildings, and the like.  
         [0030]    Preferably, and as better shown in FIG. 3, the toilet shelter generally includes a base  18 , a commode, tank, or toilet unit  20  mounted to the base  18 , a loop enclosure  22  circumscribing the base, and a roof  24  mounted to the loop enclosure  22 . The base  18  is preferably constructed of wood, such as from a standard square pallet. The base  18  also preferably includes a non-skid floor material as a sanitary top surface of the base  18 . Alternatively, the base  18  can be produced from plastic or any other cost-effective material. A toilet seat  26  is mounted to the toilet unit  20  and a urinal  28  is mounted either to a portion of the loop enclosure  22  or is mounted directly to the toilet unit  20  itself. Nonetheless, the urinal  28  drains to the toilet tank  20  as is well known in the art, such as with a flexible tube. A stackpipe  20 A extends upward from the toilet unit  20  and out of the roof of the toilet shelter. Such base  18  and toilet unit  20  construction is well-known in the art and is consistent with Porta-John® brand portable toilets. Alternatively, it is possible to not use the base  18  at all, or rather, use level ground as the base  18 .  
         [0031]    Circumscribing the base  18 , the loop enclosure  22  is preferably constructed of a loop of walls including a front end wall  30 , a back end wall  32 , and left and right side walls  34  and  36  connected therebetween. The term loop is not limited herein to only circular or closed loop structures. Those skilled in the art will appreciate that each of the individual walls are preferably made of polyethylene, but can alternatively be made from wood or any other cost effective material. As is well known, the front end wall  30  includes a door  38  to permit access to the interior of the portable toilet shelter  10  through the front end wall  30 . Located between the base  18  and the loop enclosure  22  at each of the four corners  12  are four angled supports  40 , as also shown in FIGS. 4 and 7. The angled supports  40  are preferably fastened to the inside of the loop enclosure  22  with a hook and loop fastener material  40 A, as shown in the enlarged view of FIG. 4. Accordingly, the angled supports  40  act as gussets to help rigidify the inside of the loop enclosure  22  at the corners  12  thereof. Additionally, the angled supports  40  snugly locate the base  18  within the loop enclosure  22 .  
         [0032]    [0032]FIG. 5 illustrates another aspect of the present invention wherein the toilet unit  20  includes a tank portion  42  having a lid  44  pivotably connected thereto by hinges  46 . This fliptop arrangement facilitates improved waste removal from the tank portion  42  and enables storing the urinal  28  within the tank portion  42  for better transportability of the portable toilet shelter  10 .  
         [0033]    [0033]FIG. 6 illustrates a portable toilet shelter  110  according to an alternative embodiment of the present invention wherein the roof  24  and a floor  48  are hingedly connected to the loop enclosure  22  with flexible hinge strips  14 . The hinged roof  24  and floor  48  facilitate assembly and disassembly, and increase the strength of the portable toilet shelter  110  by integrating the components thereof. The floor  48  also provides an improved barrier against entry by vermin such as small mice and rats that can squeeze through spaces between the base and walls of prior art structures.  
         [0034]    As best shown between FIGS. 6 and 7, the front end wall  30  of the loop enclosure  22  further includes top and bottom longitudinal ends  30 A and  30 B, an inward surface  30 C, and left and right vertical edges  30 D and  30 E. Similarly, the back end  32  wall includes top and bottom longitudinal ends  32 A and  32 B, an inward surface  32 C and left and right vertical edges  32 D and  32 E. The left side wall  34  also includes top and bottom longitudinal ends  34 A and  34 B, an inward surface  34 C, and front and rear vertical edges  34 D and  34 E. Finally, the right side wall  36  includes top and bottom longitudinal ends  36 A and  36 B, an inward surface  36 C, and front and rear vertical edges  36 D and  36 E. As shown, the right vertical edge  30 E of the front end wall  30  extends longitudinally parallel with and transversely normal to the front vertical edge  36 D of the right side wall  36 , and the rear vertical edge  36 E of the right side wall  36  extends longitudinally parallel with and transversely normal to with the right vertical edge  32 E of the back end wall  32 . Similarly, the left vertical edge  32 D of the back end wall  32  extends longitudinally parallel with and transversely normal to the rear vertical edge  34 E of the left side wall  34 , and the front vertical edge  34 D of the left side wall  34  extends longitudinally parallel with and transversely normal to with the left vertical edge  30 D of the front end wall  30  to establish the loop.  
         [0035]    To close the loop, the walls  30 ,  32 ,  34 , and  36  are interconnected by the flexible hinge strips  14 , which are preferably composed of fabric woven from any durable and flexible material such as nylon. Alternatively, the flexible hinge strips  14  could be constructed in any other cost effective manner, such as with sheet material, wire, some types of metal hinges, or any other flexible material. It is contemplated that the loop enclosure  22  not always be fixedly closed by the flexible hinge strips  14 . In other words, it is possible to have one of the flexible hinge strips  14  be easily removably attached to one of the four walls  30 ,  32 ,  34 , and  36 , to permit the loop enclosure  22  to be completely unfurled to a flat state. At the bottom of the loop enclosure  22 , the bottom longitudinal ends  30 B,  32 B,  34 B, and  36 B of each of the walls  30 ,  32 ,  34 , and  36  together define a bottom end  50  of the loop enclosure  22 , circumscribe the base  18 , and can be fastened to the base  18  by any well known method such as using screws, X-tree fasteners, and the like. However, when using the angled supports  40  it is not necessary to fasten the loop enclosure  22  to the base  18 , since the angled supports  40  frictionally interpose the loop enclosure  22  and the base  18  to provide sufficient stability for the portable toilet shelter  10 .  
         [0036]    Likewise, the roof  24  mounts to the loop enclosure  22  either independently or hingedly to complete the portable toilet shelter  10 . The top longitudinal ends  30 A,  32 A,  34 A, and  36 A of each of the walls  30 ,  32 ,  34 , and  36  together define a top end  52  of the loop enclosure  22 . The roof  24  is mounted to the top end  52  of the loop enclosure  22 , preferably circumscribing the top end  52  as shown and being fastened with screws, X-tree fasteners, or the like. The roof  24  is a substantially square piece, preferably formed from polyethylene and includes a stackpipe vent  24 A.  
         [0037]    Disassembly and assembly of the portable toilet shelter  10  is easier than prior art structures and requires only about five minutes by an experienced service person. The portable toilet shelter  10  is more easily disassembled than the toilet shelters of the prior art. The roof  24  is removed by unscrewing or shearing off the fasteners, lifting the roof  24  off the top end  42  of the loop enclosure  22 , and loading the roof  24  to a truck. Alternatively, according to the portable toilet shelter  110  of FIG. 6, the roof  24  can be pivotably lifted off the top longitudinal end  52  of the loop enclosure  22 .  
         [0038]    Then, the loop enclosure  22  is lifted away from the base  18  and is placed on its side permitting it to automatically fold flat on the ground, as depicted by FIGS. 8 and 9. As shown in FIG. 9, when the loop enclosure is placed on its side and permitted to collapse, the front and back end walls  30  and  32  fold relatively toward respective side walls  34  and  36 . In other words, the walls  30 ,  32 ,  34 , and  36  collapse toward one another such that the inside surface  30 C of the front end wall  30  overlays one of the inside surfaces  34 C or  36 C of one of the side walls  34  or  36 , while the inside surface  32 C of the back end wall  32  overlays the other of the inside surfaces  34 C or  36 C of the side walls  34  or  36 . Additionally and alternatively according to the collapsed portable toilet shelter  110  of FIG. 9A, the roof  24  and floor  48  can be collapsed and folded together with the loop enclosure  22 .  
         [0039]    Finally, once the loop enclosure  22  is set aside or loaded to a truck, the emptied toilet unit  20  is removed from the base  18  and loaded to a truck and the base  18  is then lifted from the ground and loaded to a truck. Accordingly, the compact collapsed loop enclosure  22  can be stacked in any convenient manner to maximize the number of units transportable by a truck. As used herein, the term overlay is synonymous with superimpose and is not limited herein to exact matching alignment of one wall over another. Rather, the term means that one wall substantially covers another with surface area misalignment permissible.  
         [0040]    The portable toilet shelter  10  is also easier to assemble than toilet shelters of the prior art. First, the base  18  is positioned on level ground. Then the toilet unit  20  is mounted atop the base  18 . Next, the loop enclosure  22  is easily opened from its collapsed condition a shown in FIG. 9 to a self-supporting condition by spreading the walls away from one another. Consequently, the side walls  34  and  36  are positioned substantially parallel to one another, the end walls  30  and  32  positioned substantially parallel to one another, and thus the side walls  34  and  36  are substantially transverse to the end walls  30  and  32 . The angled supports  40  are removably fastened to the inside of corners  12  of the bottom end  50  of the loop enclosure  22  for rigidity. From this self-supporting position, the loop enclosure  22  is lifted over the toilet unit  20  and the bottom end  50  is easily aligned with the perimeter of the base  18  such that the bottom end  50  of the loop enclosure  22  circumscribes the base  18  and angled supports  40 . Thus, it is not necessary to struggle with prior art bi-fold side walls, by trying to keep the bi-fold sides fully open and straight so as to align with the perimeter of the base. As such, the present invention is easier to assemble and therefore takes less time to do so. Once the loop enclosure  22  is firmly in place, the roof  24  is placed to the top end  52  of the loop enclosure  22  and is fastened thereto. Finally, the stackpipe  20 A is attached to the toilet unit  20 .  
         [0041]    According to the alternative embodiment of FIGS. 6 and 9A, the portable toilet enclosure  110  is assembled first by opening the loop enclosure  22  such that the walls are substantially square to one another. The floor  48  is then flipped into place at the bottom end  50  of the loop enclosure  22 . Then the angled supports  40  are removably fastened to the inside of corners  12  at the bottom end  50  of the loop enclosure  22 . The base  18  is then inserted into the loop enclosure  22  through the door  38  and placed on the floor  48  inside of the angled supports  40 . The toilet unit  20  is then dropped into the loop enclosure  22  either through the open top end  52  or through the door  38 . The roof  24  is then flipped over into place such that it circumscribes the top end  52  of the loop enclosure  22 . Finally, the stackpipe  20 A is attached to the toilet unit  20 .  
         [0042]    While the present invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. In other words, the teachings of the present invention encompass any reasonable substitutions or equivalents of claim limitations. For example, the structure, materials, sizes, and shapes of the individual components could be modified, or substituted with other similar structure, materials, sizes, and shapes. One specific example includes using a tri-fold design, or other geometry, instead of the quad-fold design disclosed herein. Those skilled in the art will appreciate that other applications, including those outside of the portable toilet shelter industry, are possible with this invention. Accordingly, the present invention is not limited to only portable toilet shelters and the scope of the present invention is to be limited only by the following claims.