Abstract:
A fire pit designed to be stored and shipped in a flat configuration, and assembled without tools in a matter of minutes into a freestanding, durable structure capable of functioning as well or better than a non-collapsible fire pit. The fire pit comprises an essentially flat base with a unique slot and flange structure adapted to receive and support side panels. The side panels include female sides with vertical corner members on their side edges that allow flat male sides to mate securely with the female sides, and with the intersecting edges of the sides both covered and reinforced for a neat appearance and robust structure. A top includes a slot and flange structure that fits over and unifies and hides the upper edges of the sides, completing the assembly.

Description:
RELATED APPLICATIONS/PRIORITY BENEFIT CLAIM 
       [0001]    None. 
       FIELD 
       [0002]    The subject matter of the present application is in the field of portable fire pits and propane tank storage containers. 
       BACKGROUND 
       [0003]    Portable fire pits made from iron, steel, aluminum, ceramic and other fireproof materials are widely used for outdoor fire containment on lawns, on patios, on decks, in backyards, on beaches, and generally anywhere it is desired to enjoy an open fire without marring the landscape or platform. Fire pits can also reduce the worry associated with having an uncontained fire in such locations. 
         [0004]    Quality fire pits are generally bulky and heavy, and can be difficult and expensive to ship from a manufacturer or seller. While it is known to make campfire “rings” collapsible for portability or shipping, they tend to be light but not very durable or long-lasting, and they lack a bottom plate for lawn and patio use. Heavier-duty fire “pits” with substantial bottom plates or bowls are suitable for long-term lawn and patio use, but are not made to be packed flat for shipping, and they can be difficult to assemble, requiring tools and special fasteners. 
         [0005]    Fire pits typically burn wood, charcoal, and other combustibles, but gas-burning fire pits are becoming more common, in which a gas fire insert or burner, often fueled from a portable propane tank, is installed in the fire pit and supplied with gas from the tank. A problem with gas fire pits, gas grills, and other propane-fueled devices is the unsightly nature of portable propane tanks. Common attempts to hide such propane tanks include homemade solutions such as garbage cans with holes cut in the sides for fuel hoses, and cabinets built into grills, but these tend to be unsightly, and at a minimum they are bulky and thus difficult to store or ship. 
       BRIEF SUMMARY 
       [0006]    I have invented a box-shaped, heavy-duty fire pit that can be made from thick metal plate such as steel for sustained lawn and patio use, that can be assembled/disassembled easily and quickly without tools, and that packs flat for cost-effective shipping. 
         [0007]    “Box-shaped” is used herein to include any multi-sided (polygonal) shape with three or more substantially flat sidewalls. “Lawn and patio” is used herein to mean any location where a fire pit needs a bottom to protect the underlying platform or ground from burning or scarring. 
         [0008]    My fire pit uses a unique joinery between the sides and the bottom and the top to achieve this functionality. The fire pit has a base comprising a substantially flat polygonal bottom panel, with raised peripheral side edges defining a preferably continuous side edge, and raised interior flanges generally parallel to and spaced inwardly from each of the side edges to define receiving slots between the side edges and the flanges. The raised interior flanges are preferably discontinuous relative to the continuous side edge, preferably extending only partway between the corners of their respective sides and centered on their edges, to facilitate ease of assembly and re-assembly after burning. 
         [0009]    The fire pit has at least three sides, each side comprising a substantially flat side panel, with at least two of the sides preferably comprising at least one angled vertical outer corner piece connected to a side edge of the side panel and generally parallel to and spaced outwardly from and covering the associated side edge, the vertical outer corner piece optionally having a vertical gap or slot between the side edge of the panel and the corner. In a preferred, rectangular form, the fire pit comprises two female sides each with two corner pieces, and two male sides with no corner pieces. The two male sides each comprise a substantially flat side panel with two male side edges adapted to fit the corner pieces on the female sides. 
         [0010]    The fire pit also has a substantially flat top plate with a top opening, and a preferably continuous inner vertical locking frame offset outwardly from the inner edge and extending downwardly from an inside surface of the top plate around the opening in a polygonal array corresponding to the base and the upper edges of the assembled sides. The top further includes preferably discontinuous interior vertical locking flanges generally parallel to and spaced inwardly from the inner locking frame and spaced outwardly from the inner edge to define joining slots between the inner locking frame and the inner edge. 
         [0011]    The base, the sides, and the top plate are substantially flat, and they pack substantially flat for shipping. For assembly, the female sides fit vertically into some of the receiving slots in the base, and the male sides (or those sides with one or more free edges) fit vertically into the other receiving slots in the base and behind the outer corner pieces of the female sides. The joining slots in the top fit vertically over upper edges of the upright assembled sides to lock the sides in place. 
         [0012]    All edges of the top, bottom, and side panels are hidden from view, and framed, by the corner pieces and by the vertical edge and flange structures. This gives the assembled fire pit a consistent, tool-finished look, and also reinforces the fire pit structurally. 
         [0013]    My fire pit construction is also useful for providing sturdy, protective, decorative storage for portable propane fuel tanks of the type commonly used to fuel grills and gas-burning fire pits. By closing or covering the top plate opening and/or providing a door in either the top or a side plate, and by using an existing opening or providing a dedicated hose port, the fire pit alternately functions for propane tank storage. I will refer to this use as a “fire pit accessory”. Alternately, the same fire pit used for holding fires in-season can be used for propane tank storage off-season. 
         [0014]    These and other features and advantages of the invention will become apparent from the detailed description below, in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of a fire pit according to the invention, disassembled and packed flat for shipping. 
           [0016]      FIG. 2  is a perspective view of the base from  FIG. 1  separated from the remaining disassembled/stacked pieces. 
           [0017]      FIG. 3  is a perspective view of the female side plates from  FIG. 1  being assembled to the base plate. 
           [0018]      FIG. 4  is a perspective view of the male side plates from  FIG. 1  being assembled to the base plate and female side plates. 
           [0019]      FIG. 5  is a top plan view of the partially assembled fire pit of  FIG. 4 , with the male and female side plates assembled to the base plate. 
           [0020]      FIG. 6  is a perspective view of the top of the fire pit from  FIG. 1  being assembled to the upper edges of the side plates. 
           [0021]      FIG. 7  is a perspective view of the fully assembled fire pit of  FIG. 1 . 
           [0022]      FIG. 8  is a perspective view of the fire pit of  FIG. 7 , modified for propane tank storage. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Referring first to  FIG. 1 , a disassembled fire pit  10  is shown in exemplary form in order to teach how to make and use the claimed invention. Fire pit  10  includes a substantially flat base  12 , substantially flat female sides  14 , substantially flat male sides  16 , and a substantially flat top  20 . The illustrated fire pit  10  is rectangular when assembled, specifically square, with four square side panels and square top and base plates. It will be understood, however, that non-rectangular fire pits with three or more substantially flat sides, are possible. It will also be understood that although the outside edge geometry of the base  12  and top  20  preferably match the polygonal shape defined by the assembled flat sides  14  and  16 , they may take other shapes provided they connect the assembled flat sides in the requisite polygonal shape. 
         [0024]    The illustrated fire pit  10  is made from heavy-gauge sheet or plate steel, although other fireproof metals or non-metals or combinations thereof could be used. 
         [0025]    Still referring to  FIG. 1 , base  12 , sides  14  and  16 , and top  20  pack essentially flat for shipping, portability, and storage. Female sides  14  each include corner pieces  15  on their edges  14   b  that are aligned vertically for assembly, and in the square panel embodiment illustrated, the free upper and lower edges  14   c  and  14   e  (best seen in  FIG. 3 ) of each female side  14  nest or mate within the corner pieces  15  on the other of the two female sides, due to the outward spacing of the corner pieces from the edges of the flat panel portions  14   a , to further reduce the volume of the disassembled and flat-packed fire pit  10 . Corner pieces  15  extend less than the full length of sides  14   b , leaving exposed portions of edges  14   b  extending beyond each end of each corner piece. 
         [0026]      FIG. 2  shows base  12  removed from the stack of disassembled fire pit parts and laid flat with its inner side facing up. Base  12  includes a flat bottom plate  12   a , raised side edges  12   b  defining a continuous raised peripheral outer flange, and interior locking flanges  12   c  generally parallel to and spaced inwardly from the side edges  12   b . In the illustrated example, interior locking flanges  12   c  are formed from L-shaped angle iron welded or otherwise secured to the inner face of bottom plate  12   a . Locking flanges  12   c  define assembly slots  13  between the flanges and the raised side edges  12   b . In the illustrated example, flanges  12   c  are discontinuous relative to side edge  12   b , only extending partway along their respective side edges, for example being centered relative to each side edge  12   b  of base  12  and spaced from each end (corner) of each side edge  12   b.    
         [0027]    Base  12  may include other features, including but not limited to one or more holes P for ash removal or use as a fuel hose port, and removable feet/legs and associated structure for attaching the feet/legs. 
         [0028]      FIG. 3  shows the female side plates  14  being assembled to base  12 . Free edges  14   c  are inserted into slots  13  defined between locking flanges  12   c  and raised side edges  12   b . Slots  13  are sized to receive and hold side plates  14  in an upright, freestanding manner without the need for tools or fasteners. 
         [0029]    Female side plates  14  include flat panel portions  14   a  and optional (but preferred) corner-forming pieces  15  running along their vertical side edges  14   b . In the illustrated embodiment, corner pieces  15  are angle iron with one leg  15   a  welded or otherwise secured to the outer faces of the side plates, and the other leg  15   b  free. Corners  15   c  are preferably spaced from edges  14   b , creating a gap for receiving the edge of a mating male side. While the structural integrity of the assembled fire pit is assured by the locking flange connections between base  12  and top  20  and the top and bottom edges of the sides  14  and  16 , corners  15  can provide some structural reinforcement if toleranced with a close enough fit to the male side edges, and enhance the finished look of the fire pit. 
         [0030]      FIG. 4  shows male sides  16  as flat panels dimensionally identical to panel portions  14   a  of female sides  14 , although the “front” panel is illustrated with an optional decorative or functional opening or cutout  16   d . The lower edges  16   a  of male side plates  16  fit the remaining slots  13  in base  12 , and their side edges  16   b  fit behind the free legs  15   b  of corner pieces  15 . In the illustrated example, best shown in  FIG. 5 , side edges  16   b  are spaced from corners  15   c , shown as gap  17 , to provide some assembly tolerance and to accommodate warping and ash build-up, and to ensure easy nesting of the free sides  14   c  and  14   e  of each female side  14  between the corner pieces  15  of the other female side  14  when packed flat as shown in  FIG. 1 . 
         [0031]      FIG. 5  shows a preferred joined relationship of female sides  14  and male sides  16  once they are assembled into the slots  13  in base  12 , and their edges/corners are engaged with one another in a unified structure. Optional additional corner pieces  115  can be added to the interior side edges of male sides  16  as illustrated in phantom lines. Optional additional corner pieces  115  would form a structural slot and reinforcement for the corner-supporting side edges  14   b  of the female sides  14  when the male sides  16  are joined with the female sides, and would make the entire fire pit more solid when fully assembled. 
         [0032]      FIG. 6  shows top plate  20  with a square outer frame  20   a  having inner edges  20   b  in a square shape defining a square opening  20   e  matching the arrangement of the upper edges of the assembled sidewalls  14  and  16 . A vertical inner locking frame  20   d  extends downwardly from the interior surface of frame  20   a , spaced outwardly from inner edges  20   b  of opening  20   e  and defining a continuous peripheral flange around the opening on the underside of the top plate matching the square shape of the assembled sides  14  and  16 , and overlying and hiding the upper edges of the sides  14  and  16  when assembled. 
         [0033]    Discontinuous interior locking flanges  20   c  (similar to locking flanges  12   c  in base  12 ) are spaced outwardly of inner frame edges  20   b  and inwardly of vertical framing flanges  20   d  to define partial-length joining slots  21  between them, preferably centered with respect to each side. Fire/smoke opening  20   e  is defined by inner edges  20   b , for example matching the square shape of the assembled sidewalls, although the shape of opening  20   e  can vary, like the shape of the outer frame portion  20   a  of top plate  20 . Top  20  is placed over the upper edges  14   e  and  16   e  of previously assembled sides  14  and  16 , with upper edges  14   e  and  16   e  inserted in slots  21 , to securely lock the assembled sides together. 
         [0034]      FIG. 7  shows the assembled fire pit  10 , and how all edges of sides  14  and  16  are hidden behind the flanges  12   b  and  20   d  and corner pieces  15 . The appearance of fire pit  10  is accordingly uniform and neat, and gives the impression of a non-collapsible fire pit. The resulting structure is also sturdy, with very little play between the assembled pieces despite the lack of fasteners, and allows the use of thick steel or other plate material for the base, sides, and top for durability and longevity.  FIG. 7  also shows an optional recessed “shelf” formed by inner edges  20   b  when inner edges  20   b  are created by angle iron used for vertical frame  20   d . The horizontal legs of the angle iron that form inner edges  20   b  extend beyond the inner edge  20   b ′ defined by the opening cutout in top plate  20 , in a plane below that of the upper surface of top plate  20 , such that a decorative or functional cover such as a glass or metal plate (see  FIG. 8 ) can be fitted securely onto the shelf formed by angle iron legs  20   b  to close opening  20   e.    
         [0035]    Disassembly of the fire pit is simply done in reverse of the operations shown in  FIGS. 1-6 . Top  20  is removed first, followed by male sides  16 , followed by female sides  14 , until the fire pit is stacked flat again for storage or shipping, as in  FIG. 1 . 
         [0036]      FIG. 8  shows the collapsible fire pit modified with a cover  38 , a side panel door  40  in “front” side  16  in place of the decorative cutout, and an additional dedicated hose port P in side  14  to make the fire pit more useful for storing a propane tank, for example a 20-lb propane tank of the type commonly used for barbecue grills, although the size may vary. The basic flat panel structure  12 ,  14 ,  16 , and  20  is essentially unchanged, and still stacks flat as shown in  FIG. 1  and assembles and disassembles without tools or fasteners as shown in  FIGS. 2 through 6 . It will be understood that although both a top cover  38  and side door  40  are shown, one of these two access features would be sufficient for inserting or removing the illustrated propane tank. It will also be understood that the modifications of  FIG. 8  could be originally manufactured into the fire pit structure to make it a dedicated propane tank holder, or they could be added-on to a fire pit used for burning in some seasons and then used for propane tank storage in other seasons. It will be further understood that the illustrated propane tank holder of  FIG. 8  could also be used as a fire pit, without modification, when not used for tank storage. 
         [0037]    A further advantage of using the same structure for both fire pit and propane tank storage uses is that two such devices could be used side by side on a patio, etc., one as a fire pit and the other as a propane tank holder, while providing an aesthetically matching look. 
         [0038]    In the preceding description, various aspects and examples and configurations of making and using the invention as defined by the claimed subject matter (the “invention”) have been described, for purposes of explanation, to provide a thorough understanding of the invention, and to enable those skilled in the art to make and use the invention. It will be understood that the disclosed embodiments are representative of presently preferred forms of the invention, but are intended to be explanatory rather than limiting of the scope of the invention as defined by the claims below. Variations and modifications of the invention as disclosed in the foregoing written specification and drawings are possible without departing from the scope of the invention as defined in the claims below. It should further be understood that the use of the term “invention” in this written specification is not to be construed as a limiting term as to number of inventions or discoveries or the scope of any invention or discovery, but as a descriptive term which has been used conveniently to describe advances in science and the useful arts. The scope of the invention is accordingly defined by the following claims.