US 20010015137 A1
A removable firebox for use in a portable, collapsible barbecue grill including retractable heating grate on top of the firebox and a retractable mid-level cooking grill for providing high-temperature cooking. A lower main grill is disposed in a base cavity of the barbecue grill for providing moderate temperature cooking. The firebox rests in the base cavity of the grill housing and provides heat to a cooking area defined by the base cavity, an upper lid of the housing and a pair of side walls extending upward from the base cavity. The firebox and/or the upper lid includes insulation and/or cooling baffles to protect users from heated surfaces. Venting is provided from the sides and rear of the grill housing. When collapsed, the grate and grills fold onto or are retracted within the firebox, and the entire firebox assembly is stowed in a sealed grill housing. The top and bottom portions of the grill housing mate to form a sealed container-like structure for convenient transportability or storage. The barbecue grill also includes foldable legs which lock into extend position, when deployed.
1. A removable firebox having a retractable heating grate and a retractable cooking grill for providing heat to a cooking area formed by a base cavity and extended side walls of a collapsible barbecue grill, said barbecue grill also having a top cavity that mates with said bottom cavity and said bottom cavity is constructed to carry said firebox during stowing, said firebox comprising:
a generally vertically disposed container for holding a source of fuel, said container having an open top and a lower confine defining a bottom, opposed confines defining front and rear segments, and opposed confines defining side segments,
said front segment being constructed to permit radiation of heat from said source of fuel,
said firebox including supports for pivotally supporting a mid-level cooking grill between retracted and extended positions and for supporting said mid-level cooking grill in a generally horizontal position between the top and bottom of said firebox, and
said firebox further including supports for engaging and supporting a heating grate, which supports a pot or kettle directly over said source of fuel.
2. A barbecue grill comprising:
a base cavity that mates with said lid,
a pair of sidewalls each being pivotably supported on one of said lid and said bottom cavity, said sidewalls extending upwardly from said base cavity when deployed thereby to further define a cooking area between said side walls,
a firebox comprising a generally vertical enclosure that holds a source of heat, said enclosure including an open top, a bottom, a front, a rear, and opposed sides wherein said front is substantially planar and permits radiation of heat from said source of heat,
said base cavity of barbecue grill including a support mechanism that supports said firebox in a generally upright position near a rear portion of said base cavity, and
at least one cooking grill connected with said firebox and adapted for movement between extended and retracted positions.
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11. A removable firebox for use in a vertical hearth barbecue grill, said firebox comprising:
an enclosure that holds a source of heat and including an open top, a bottom, a front, a rear, and opposed sides wherein said front is substantially planar and permits radiation of heat from said source of heat, and
at least one cooking grill pivotably connected with said firebox and adapted for movement between extended and retracted positions.
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 Outdoor cooking and barbecuing have become significant activities, but traditional barbecue grills have remained unchanged for quite a while. However, grills with vertical hearths have been known in the art for some time. See, for example, U.S. Pat. Nos. 3,999,472 to Einto, 3,783,855 to Newinger, 3,611,912 to Choc, 3,550,525 to Rabello, 3,175,549 to Bergsten, as well as that art mentioned in commonly-owned related U.S. Pat. No. 5,823,174 to Andress. It is believed that vertical grills have not been significantly utilized because prior models lacked convenience, practicality and efficiency.
 For example, the vertical grill disclosed by commonly-owned U.S. Pat. No. 5,823,174 advantageously provided a vertical hearth that extended below a main cooking grill whereby convective and radiant heat from a heat source covered a relatively larger cooking area. Coupled with sidewalls, this grill design increased the amount of main grilling surface that was usable for grilling, roasting or baking. Also, prior vertical grills neither provided multiple cooking temperatures at plural cooking levels nor did they provide kettle rack in combination with other grilling surfaces. In addition, prior grills did not provide deployable or extendable grate or grill members that facilitated portability and stowing. Rotisserie rods were used in the past, but not in combination with multiple multi-temperature grilling surfaces. Also lacking in prior models was a removable firebox that accommodated these features. The present invention, however, overcomes many of these as well as other drawbacks and disadvantages.
 It is therefore an objective of the present invention to provide a rapidly deployable, portable and/or stationary barbecue grill having a removable firebox that co-acts with a cooking chamber to provide multi-temperature cooking.
 It is another objective of the present invention to allow such rapid deployment by providing collapsible barbecue grill components, such as folding legs and fold-out side walls, and at least one deployable cooking grid pivotally attached to a firebox.
 It is another objective of the present invention to provide a firebox construction that supports at least one deployable and retractable heating grate and/or cooking grill.
 It is a further objective of the present invention to provide a firebox-barbecue grill combination where the two, when deployed, act together to create multiple heating surfaces at multiple cooking temperatures to permit simultaneous cooking of varied food items.
 It is yet another objective of the present invention to provide a firebox-barbecue grill housing combination wherein, upon deployment, airflow is provided at the rear and/or lower portions of the firebox thereby minimizing cooler air draft within or about the cooking chamber.
 It is yet a further objective of the present invention to provide radiant-reflective surfaces in and/or about the firebox receptacle thereby confining and directing heat to a main cooking chamber of the barbecue grill.
 It is yet a further objective of the present invention to provide a barbecue grill that supports rotisserie rod, including manual, mechanical or electro-mechanical drive means for the rotisserie rod.
 It is another objective of the present invention to provide a firebox-barbecue grill housing construction that permits efficient cooling of housing parts.
 It is another objective of the present invention to provide a barbecue grill with a large amount of grilling surface without substantially increasing the overall weight of the barbecue grill.
 It is yet another objective of the present invention to provide sufficient heat beneath a main cooking grill thereby increasing the available cooking area of the main cooking grill.
 It is also an objective of the present invention to provide a fixed, deployed barbecue grill having the above-specified objectives, wherein various components thereof (legs, grates, firebox, grills, sidewalls, etc.) may be secured or fastened in a fixed position rather than being retracted.
 It is another objective of the present invention to provide a barbecue grill construction that is conveniently manufactured, either using sheet metal or aluminum casted housing parts.
 It is a further objection of the present invention to provide a durable anti-warping firebox construction that resists warping when heated.
 It is yet a further objective of the present invention to provide a firebox-grill housing combination that facilitates cooling and heat shielding of grill housing parts during fuel oxidation by providing insulation within and/or upon said grill housing and/or providing cooling baffles upon said firebox and/or grill housing.
 In accordance with the invention, a firebox having at least one deployable cooking grill provides heat to a cooking area generally defined by a base cavity and extended side walls of the barbecue grill is provided with a fixed or collapsible barbecue grill. The firebox generally comprises a vertically disposed enclosure having an open top, a bottom confine, opposed front and rear confines, and opposed side confines for restricting a source of fuel within boundaries. The front confine, which may comprise a grate, wire mesh, or expanded metal, permits radiation of heat from a fuel source, e.g., charcoal briquettes, wood chips, lava rocks. The firebox also includes supports for supporting a mid-level cooking grill in a substantially horizontal position between the top and bottom of said firebox. In a refinement of the invention, the firebox includes a pivoting mid-level cooking grill for high-temperature cooking and a deployable kettle rack directly over the burning fuel for heating a pot or kettle.
 In another aspect of the invention, the firebox, with or without a deployable grate or grill, forms the vertical hearth of a barbecue grill and is storable in the base cavity when not in use. When fully deployed, however, the firebox stands upright in spaced relation to a rear housing wall or lid thereby facilitating cooling of (or reducing heat transfer to) the outer grill housing.
 These and other multiple objectives, advantages, and aspects of the invention will become more readily apparent in view of the description of illustrative embodiments and the accompanying drawings. The invention, though, is pointed out with particularity by the appended claims.
FIG. 1A is a perspective view of a removable firebox having deployable grills according to one aspect of the present invention.
FIG. 1B is also a perspective view of the embodiment of FIG. 1A without deployable grills.
FIG. 1C is a perspective view of another embodiment of a removable firebox according to another aspect of the present invention.
FIG. 1B., 1E., 1F, 1G, and 1H are conceptual illustrations of a firebox according to various other aspects of the present invention.
FIG. 2A is a perspective view of a fully deployed barbecue grill including a vertical hearth in accordance with an aspect of the present invention.
 FIG. FIG. 2B depicts support flanges for a main grill within the base cavity of the barbecue grill.
FIG. 2C shows a pivoting support structure for side walls attached to the upper portion of a barbecue grill housing.
FIG. 2D depicts a support flange for sustaining a mid-level grill in a horizontal position according to an aspect of the present invention.
FIG. 3 depicts an exemplary supporting structure for a rotisserie rod between side walls of a barbecue grill constructed according to an aspect of the present invention.
FIG. 4A shows folding legs together with supporting structure on the underside-of the lower portion of the barbecue grill housing according to an aspect of the present invention.
FIG. 4B illustrates further details of the supporting structure of FIG. 4A.
FIG. 4C depicts yet further details of the supporting structure of FIG. 4B.
FIG. 5 shows folding legs of the barbecue grill in a retracted position.
FIG. 6A shows a sealed barbecue housing of sheet metal construction according to an aspect of the present convention.
FIG. 6B shows construction details of the upper housing for a barbecue grill according to a sheet metal construction.
FIG. 6C illustrates attachment details of the structure of FIG. 6B.
FIG. 6D and 6E illustrate rotational attachment between a side wall and the upper housing of a barbecue grill according to one aspect of the present invention.
FIG. 7A depicts a side view of the sheet metal version of a barbecue grill including a removable firebox according to one aspect of the present invention.
FIG. 7B is a front view of the barbecue grill of FIG. 7A.
FIGS. 8A and 8B are conceptual drawings of a collapsible barbecue grill according to yet another aspect of the invention.
FIG. 8C is a conceptual drawing of a removable firebox for the barbecue grill of FIGS. 8A and 8B.
 As indicated above, objectives of the invention include providing a firebox separate and apart from a barbecue grill whereby to provide, among other things, convenient cleanup after use, protection of barbecue grill housing from extreme heat, self-contained storage of grill components, transportability, collapsibility and rapid deployment of barbecue grill and grill components. These objectives are provided, in part, by, for example, a removable firebox 10 illustrated in FIGS. 1A and 1B. In the illustrated embodiments, the firebox 10 provides a vertical hearth for a barbecue grill and comprises a generally vertical enclosure having an open top 11 and confines for holding fuel such as charcoal, briquettes, wood chips and the like. A source of fuel may also include a source of gas, a gas burner, and lava rocks within the firebox. The firebox 10 has at least one planar surface in front and is generally shown to have a rectangular cross-sectional structure, but in practice, may take on a variety of forms or shapes. As illustrated in FIGS. 1A and 1B, however, the confines include side walls 12 a and 12 b, a rear wall 20, the bottom confine 16, and a front confine comprising a grill 26. Although illustrated in sheet metal construction, the firebox may also include a steel or cast iron frame in order to provide strength to prevent warping of the firebox when exposed to the extreme heat of burning fuel. Stiffening ribs may be stamped into the sheet metal in order to improve warping resistance to heat. Alternatively, portions of or all surfaces of the firebox may be constructed of a wire mesh, expanded metal, steel rods, or other materials.
 The bottom portion of the firebox 10 includes a raised flange 18 having a plurality of air vents 24, which assist in maintaining an air draft that supplies the fuel during oxidation thereof. Additional groups of vents 22 a and 22 b are provided in the bottom portion of the sides 12 a and 12 b of the firebox. The firebox 10 also includes a pair of tabs 28 a and 28 b for providing pivot points for a rod 31 of a mid-level 30, a pair of flanges 27 a and 27 b for supporting a grate grill as a front confine of the firebox, and a pair of protruding flanges 34 a and 34 b, which provide pivot points for rod 33 of kettle rack 32, i.e., a heating grate, for supporting a kettle or pot directly above burning fuel. In a deployed position, the mid-level grill 30 may be supported in a horizontal position by anchors (not shown) located on side walls of the grill housing, or alternatively, by a stop mechanism that interacts with the mid-level grill 30 and any portion of the firebox 10, such as side walls 12. The heating grate 32, when folded over onto the top of the firebox 10, may rest directly on top of the front grill 26 or on any other portion of the firebox in order to sustain the heating grate 32 in a horizontal position.
 Firebox 10 may also include cooling baffles on the sides and/or rear confines thereof in order to reduce heat transfer to the outer casing of the grill housing. Such baffles may take on a variety of constructions, from single to multi-layer sheet metal. Insulating material may also be employed to reduce heat transfer, and air flow may also be induced in the rear portion of the grill housing to facilitate cooling. Such flow may be provided by vents within and/or spacing between parts of the barbecue housing, as shown, for example, in FIG. 6A and 7A. When positioned in the base cavity of the grill housing, firebox 10 is displaced from the rear casing by at least a couple to a few centimeters in order to reduce heat transfer to the grill housing.
FIG. 1C depicts one of many alternative embodiments of a firebox. Here, firebox 10 provides a horizontal supporting mechanism for both the mid-level grill 30 and the heating grate 32. In addition, the firebox includes a mechanism for fully retracting both the mid-level grill 30 and the heating grate 32. The front of the firebox, at the lower portion, has a beveled cross-sectional shape which provides obstruction clearance during rotational movement of the firebox towards the base cavity of the barbecue grill. In particular, studs 36 a (not shown) and 36 b co-act with pivot supports in the base cavity of the barbecue grill so that the firebox may be folded downwardly into the base cavity. When so folded, cooking grill 30 retracts to a position parallel to the front of the firebox and heating grate 32 folds upward and then retracts downwardly into the firebox.
 A deployment and retraction mechanism for the mid-level grill 30 includes extension arms 41 a and 41 b of mid-level grill 30, which co-act with flanges 38 a 38 b located on side walls 12 a and 12 b of the firebox and with friction studs 40 a and 40 b, which lock the mid-level grill 30 in a horizontal position upon rotation along path 39. A rod 43 of the front confine of the firebox, extending horizontally along the front of the firebox, provides an axis of rotation for mid-level grill 30. Grill 30 includes extended members 47 a and 47 b for grasping and/or encircling the support rod 43. Preferably, grill 30 comprises stainless-steel, porcelain coated steel or other material for providing easy cleaning and a nonstick surface.
 Although termed a mid-level grill, its horizontal position may lie at any vertical position between the top and bottom of the firebox 10, depending upon the required heat application. A higher placement provides greater heat. To meet certain other objectives of the invention, the mid-level grill should be sufficiently high enough from the bottom of the firebox to permit higher temperature cooking than that provided by a main cooking grill, which extends horizontally and perpendicular along a lower portion of the firebox. Also, it is important that at least a portion of the firebox extends below the main cooking grill in order to permit sufficient radiation and convection of heat from the fuel source into a heating area or chamber generally defined in a base cavity of the barbecue grill. These components are subsequently described in conjunction with the description of the combination of the firebox and the barbecue grill.
 Still referring to FIG. 1C, the heating grate 32 may also be retracted when rotated upwardly generally along path 50, and then displaced downwardly along path 51 when guided by slot pairs 42 a (not shown) and 42 b disposed in side walls of the firebox. Heating grate 32 includes protruding studs 49 a (not shown) and 49 b that guide the rotational and displacement motion of the heating grate 32 during retraction and deployment. The width of heating grate 32 is slightly smaller than the inside width of the firebox 10 in order to permit storage of the grate 32 inside firebox 10. Heating grate 32 may be constructed of steel, iron, or may even comprise a solid heating plate or other support structure for a pot or kettle.
FIGS. 1D, 1E, 1F, 1G, and 1H show various extension/retraction configurations of firebox grates and grills. FIG. 1D, for example, depicts a firebox 10 having a retractable heating grate 32, a retracted mid-level grill 30 and a retracted main grill 52, each being pivotally attached and supported by the firebox. FIG. 1E shows a firebox having a retractable heating grate 32 and a retracted mid-level grill 30. FIG. 1F depicts the firebox of FIG. 1E when the heating grate 32 and the mid-level grill 30 are in a deployed, extended position. FIG. 1G is a conceptual perspective diagram of a firebox 10 having deployed heating grate 32, mid-level grill 30, and main grill 52. FIG. 1H shows the firebox in relation to a barbecue grill having a lower portion 62 and upper portion 64. The firebox rests on pivot supports 66 located within the base cavity 60 of the barbecue grill. Support 66 helps to maintain the firebox 10 in a vertical position so that the mid-level grill 30 and main grill 52 may rest in horizontal positions. The barbecue grill of FIG. 1H is collapsible in the sense that the top portion 64 may fold over and mate with the lower portion 62 to provide a sealed container, which prevents ashes, fuel, cooking residue and the like from spilling when stowed or transported. The lower portion 62 of the barbecue grill provides a cradle for the collapsed firebox 10 with retracted grill members 52, 30 and 32.
FIG. 2A is a perspective view of a barbecue grill utilizing a firebox 10 as a vertical hearth. The collapsible barbecue grill shown in the illustration includes a lower portion 62 having a base cavity 60, an upper portion 64 that is adapted to pivot on hinges to mate with lower portion 62, side walls 68 a and 68 b that may be either hinged to the upper portion 64 or hinged to the lower portion 62 and adapted to be folded outward or upward, as the case may be, to define a heating area therebetween. Instead of hinging, these components may be releasably fastened together. In a stationary grill, these parts may be welded. Side walls 68 a and 68 b also include punchouts 69 a and 69 b, which provide tabs 70 a (not shown) and 70 b (FIG. 2B) for supporting mid-level grill 30 in a horizontal position. Side walls 68 a and 68 b also include rotisserie rod supports 76 a and 76 b for accepting a rotisserie rod and/or rod turning mechanism. The rotisserie rod and turning mechanism may be a standard off-the-shelf item, such as that available from Char-Broil (W. C. Bradley Co.) or other barbecue parts supplier. The base cavity 60 of the lower portion 62 of the barbecue grill include flanges 61 and 63 (FIG. 2B) for supporting the main grill 52. The base portion 62 of the barbecue grill assembly also includes foldable leg pairs 72 a and 72 b, each including respective cross-member braces 74 a and 74 b.
FIG. 2C illustrates a possible hinging mechanism between side wall 68 b and an upper portion 64 of a barbecue grill. As shown, the side wall 68 b includes studs 78 and 79 located on protruding flanges that mate with protruding flanges 80 and 81 of the upper housing lid 64 of the barbecue grill in order to provide a pivot support mechanism.
 The barbecue grill may also include insulation material in various parts thereof to protect users from extreme heat generated by oxidizing fuel in the firebox 10. Insulation may comprise a double-wall construction of lid 64 including insulating spacers, e.g., ceramic, between inner and outer walls thereof. The double-wall structure may include insulating material, such as high-temperature fiberglass or other non-combustible material. Thermal insulating material may also be place on the outside surface of lid 64 to minimize or prevent touching hot metal parts wherein the inside wall is even thermally insulated along the periphery of the double wall seal. Sidewalls 68 a and 68 b may also be coated with insulating material. Cooling baffles may be placed on the rear portion of the firebox 10 or on the inside surface of lid 64 to further reduce heat transfer to the outer housing.
FIG. 3 shows a relationship between a rotisserie rod 82 and side walls 68 a and 68 b of the barbecue grill. Rotisserie rod 82 extends through a pair of supports 85 and 87, each of which is positioned generally equidistant from a generally (but not necessarily) planar surface of the firebox. Rotisserie rod 82 also may be repositioned to a location closer to the firebox simply by utilizing support pairs 86 and 88. Side walls 68 a and 68 b may have additional sets or pairs of rotisserie rod supports. Also, a driving mechanism 84 may be attached to either side wall in order to rotate the rotisserie rod. The driving mechanism may be an electrically operated motor or a coil spring motor providing constant force or other rotation; or the rod may be manually turned during cooking. A conventional constant force coil spring motor is available from Ming Tai Industrial Co., Ltd. of Taiwan, and such a driving mechanism would include gearing, ratcheting, locking/release mechanism and spindles in a conventional way, as known in the art. To assist in circumferentially positioning a manually operated rotisserie rod, slot 87 may co-act with a generally polygon cross-sectional rotisserie rod, i.e., square, hexagonal, etc., to provide circumferential positioning when rod is lifted, rotated and re-inserted into slot 87.
FIG. 4A shows further details of folding leg pairs 90 a and 90 b on the bottom portion 62 of the barbecue grill. Each leg pair includes a flat cross member brace 92 a and 92 b, which is located on complementary inner and outer sides of the folding legs so that the leg pairs retract substantially into the same plane. FIG. 4B shows a hinging and locking mechanism for each of the folded legs. Flanges 94 and 96 support an axial pin (not shown) over which leg 98 rotates. At least one of the flange portions 96 includes a locking mechanism 97 to lock the legs in an extended position when the grill is deployed. These flanges 94 and 96 may be cast directly in the body of the grill to save labor cost during manufacturing or may comprise sheet metal flanges that are spot welded to the base 62 of the barbecue grill. Other attachment means may also be employed. FIG. 4C depicts the geometric configuration of an inset for supporting leg 98 in an extended position. In particular, a top surface 99 of leg 98 mates with a flat portion 100 that is recessed within the bottom portion 62 of the barbecue grill housing. A curved portion 102 of the recess provides clearing for rotation of leg 98 about an axis 104 (FIG. 4B) to a retracted position.
FIG. 5 shows a sheet metal construction for the retractable leg assembly. An inner leg pair 114 and 116 are attached to the base portion of the barbecue grill via flange assemblies 118 and 120, and are tied together by a flat flange 108. Flange assembly 118 and 120 provide pivoting support and a locking mechanism for the leg pair when moved from a retracted to a deployed position. An outer leg pair 110 and 112 are also supported by flange assembly 122 and 124, and are tied together by a flat flange member 106. This construction provides retraction of all legs 110, 112, 114, and 116 into substantially the same plane. Rather than having inner and outer leg pairs, the legs in each pair may be staggered over one another so that one leg lies in the inner position and the other leg lies in the outer position relative to the periphery of the base portion 62 of the barbecue grill.
FIG. 6A is a perspective view of the sheet metal constructed barbecue grill showing a mating relationship between the upper and lower housings 62 and 64. Also shown are stiffening ribs 130, 131, 132, 133 and 134, which may be die-stamped into the upper lid housing 64 of the barbecue grill. A series of air vents may also be provided in the top portion to assist in cooling. A handle 136 and locking mechanisms 138 and 139 are also provided. FIG. 6B illustrates possible construction details of the upper lid portion 64 of the barbecue grill wherein a die-stamped side member 140 may be attached by welding or other fastening to a generally con-caved structure 64. FIG. 6C depicts fastening by conventional spot welding of sheet metal portions of the upper portion 64 and side flange 140. FIGS. 6D and 6E depict an alternative hinging mechanism between a side wall 68 and upper portion 64 of the barbecue grill.
FIGS. 7A and 7B show a side view of the barbecue grill made according to a sheet metal design. As indicated earlier, the major component to the barbecue grill may also be cast using aluminum metal. Sand or shell casting is preferred using high temperature aluminum alloys selected from the group called AL 380, AL 356 and AL 142. Other metals or alloys may also be used. According to another illustrative design, a top portion 64 is hinged to bottom portion 62 by piano hinge 142. Parts of the grill housing may be cast iron to provide heat durability.
 Firebox 10 is supported by a pivot support plate 144 that is fastened to a wall within base portion 62. Pivot support plate 144 is positioned to allow the firebox to rotate downwardly into the base portion 62 to a stowed position, and to permit a portion of the firebox 10 to extend below a main grill 52 when deployed vertically. Instead of pivoting, the firebox may rest in a receptacle or cradle comprising stops, tabs, flanges, etc. fixedly attached within the cavity 60 of base 62. Importantly, the firebox 10 should extend below the main grill 52 so as to provide radiant and convective heat to a larger area underneath grill 52.
 Also shown is a buffering space 148 between the rear of the firebox 10 and grill housing 64. This helps to reduce heat transfer to the outer lid housing 64 during fuel oxidation. Housing 64 may also have a double wall construction with internal insulation, similar to an oven door, in order to shield the outer wall of the housing 64 from heat. Side walls 68 may have a similar construction. Furthermore, gaps 150 and 152 provide airflow openings to sustain an air draft for oxidizing fuel in the firebox. Such venting may also exist along the area of piano hinge 142 or within portions of the upper and lower housings 62 and 64 spanning firebox 10. Airflow through and/or about the rear and side portions of the barbecue grill may be received by corresponding air vents in the side and rear of the firebox 10, which reduces the amount of any downward draft through the main grill 52, to oxidize fuel. Such downdrafts tends to cool the heating chamber thereby reducing cooking temperatures.
 Side walls 68 include a flange assembly 146 having protruding ends that mate with tab 148 (FIG. 1C) in order to hold the firebox 10 in a vertical position commonly-owned related U.S. Pat. No. 5,823,174 and U.S. application Ser. No. 09/190118, incorporated herein, in which case a burner would be added, or the invention may be used simply with charcoal, briquettes, wood chips and the like.
 The appended claims are to be given their broadest reasonable interpretation within the limits of the prior art, and no part of the foregoing description should be viewed as limiting their construction. Unless expressly restricted by definition in the written description of the invention, words used in the appended claims are to be given their ordinary meaning.
 We claim: when deployed. The grill housing of the sheet metal embodiment of the invention is preferably power coated with baked enamel. Sheet metal of about 18 gage is believed to be satisfactory for housing construction, and where strength is required, plates may be added or stiffening ribs may be stamped therein. To reduce overall weight without reducing overall dimensions of the grill, a thinner metal, i.e., 20 gage sheet metal, and stiffening ribs may be used. A basic unit of the barbecue grill measures approximately 18″ by 24″ by 8″ but these dimensions may vary. The aluminum shell or sand casted models will have a wall thickness between approximately one-eight to one-quarter inches. Larger units of both the sheet metal and casted versions may include wheels attached to at least one pair of folding legs so that, when collapsed, the unit may be transported in a manner similar to a luggage cart. A smaller tabletop unit need not have legs, but may include insulating table mounts on the underside to shield heat. A drip pan (not shown), such as a disposable aluminum pan, may be used in the base cavity to catch grease and/or ash drippings.
FIGS. 8A, 8B and 8C are conceptual renditions of a barbecue grill assembly for receiving and supporting a removable firebox. FIG. 8A illustrates an arrangement of tabs, stops and flanges within the base cavity 60 of the lower portion 62 of the barbecue grill. FIG. 8B shows an enclosure design provided by the barbecue grill. FIG. 8C is a conceptual rendition of a removable firebox having deployed grate and cooking grill members.
 The above illustrative embodiments of the invention defined by the appended claim, and the written description and drawings are not intended to limit the subject matter of the invention. According to the teachings hereof, materials may be substituted, shapes may be altered, and the construction of grill parts may be changed without departing from the general nature and character of the invention. For example, instead of hinging and/or pivoting, any of the components mentioned above may be releasably or permanently fastened together. Rather than have a rectangular cross-sectional shape, the firebox may take on a variety of other forms, including circular, elliptical, oval, etc.. The invention may be used with lava rocks and include a gas source, as described in