with reference now to fig1 - 6 of the drawings , an illustrative embodiment of the invention is shown by numeral 10 . an enclosure 12 is provided having a thin - walled flat surfaced structure constructed of metal such as porcelain steel or aluminum . it is characterized by front wall 14 and back wall 16 which are connected by opposing side walls 18 . the walls incline upwardly from a bottom peripheral edge 20 and merge with a top wall 22 . the front wall may include an optional door and / or glass viewing means 13 . as shown , a glass door 15 is used over front wall opening 17 . the door pivots about hinges 19 , 19 with handle 21 and permits easy access to the enclosure interior . a function of the enclosure is to capture hot gases from an external heat source . it is contemplated that a likely source would be the heating means f of a conventional gas barbecue unit common to most households . as such , peripheral bottom edge 20 most preferably defines an open bottom that will overlie and cover at least a major portion of the barbecue housing open top . since most barbecue housings have a rectangular - shaped open top , bottom edge 20 should likewise define a rectangular - shaped open bottom . other shapes may also be used . with reference to fig2 it is expected that enclosure bottom edge 20 will rest upon grating g which is set over the open top of housing h of a typical gas barbecue unit . the interior cooking assembly , shown generally by reference 23 , will also be supported by the grating . the barbecue housing and enclosure cooperate to entirely enclose the assembly during the cooking operation . the interior cooking assembly illustrated in fig1 - 6 and 10 comprises a base 34 having a partition 24 upstanding from each opposing end thereof . the base length is less than the enclosure length to provide open flue areas 26 between each partition and respective side wall . base width would approximate the enclosure width so that most all hot gases from the underlying heat source f will be deflected into the flue areas . base 34 is constructed of material that is only semi - conductive of heat . this inhibits localized hot spotting from the underlying heat source . thickened plates of marble or ceramic material are preferred because they also provide a durable non - oxidizing surface suitable for direct contact with food items such as pizza crusts . partitions 24 , 24 are preferably coextensive with the base width and span the enclosure between front wall 14 and back wall 16 . it is desirable to center the base over barbecue housing h so that the partitions are equidistant from respective side walls 18 , 18 . in this way , the flue areas will be equal and permit a balanced flow of hot gases about both sides of the enclosure . as shown in the fig1 - 6 embodiment , the partitions may include opposing side flanges 27 , 27 . these help facilitate partition juncture with the front and back walls . such juncture may be a fixed attachment whereby assembly 23 will be part of the enclosure . alternatively , the interior assembly may be a separate entity for use with a separate enclosure or within existing barbecue cover and housing units as shown in fig8 - 10 and 14 - 16 . in such case , the partitions may be without side flanges 27 , 27 as depicted in fig1 . each partition terminates at an upper edge 25 . the upper edges are spaced - apart from top wall 22 a predetermined distance to form open areas . such areas function as hot gas inlets 28 to direct gases from the flues into a cooking chamber 36 . the cooking chamber is defined as the area above base 34 between the partitions and between the front and back walls . the lower portion of each partition further includes a base support means shown as inwardly directed base flange 29 . in the simplest construction , opposing ends of base 34 will rest by gravity upon a respective base flange of each partition . optionally , the base support means may include a clamping device or permanent attachment means such as bolt fasteners . in this way the partition and base would be a unitary assembly . also located in the lower portion of each partition are vent means shown as a cool gas outlet 30 . the outlet is adjacent base 34 and functions to permit cooled gases to exhaust the cooking chamber . in the fig1 - 6 embodiment , ducts 31 are used to carry the gases across the open flue areas to an enclosure outlet 32 . as best seen by the arrows in fig4 the above - described cooking assembly provides for convection flow of hot gases over the food item p being cooked . the gases cool and become denser as they flow through the chamber and across the item . the outlets , being located adjacent base 34 , allow the lower cooled gases to exit the chamber to create a natural circulatory gas flow . simultaneous with the above convection flow , the heat semi - conductive nature of base 34 readily deflects the underflow of hot gases while slowly conducting only a portion of the gaseous thermal energy . the resultant temperature gradient across the base thickness is significant and functions to eliminate unwanted hot spots at the base cooking surface . it does allow , however , the attainment of an effective base surface cooking temperature . this is especially advantageous for foodstuffs with crusts such as pizzas . with the above system , hot gases continuously flow over the pizza top to melt the cheese particles while a cooler base surface allows for cooking of the underlying crust without burning or dryness . the invention contemplates variations of the enclosure and also the interior cooking assembly to accomodate different sizes and models of barbecue units . it has been found that most commonly available barbecue units vary in length ( side wall to side wall ) rather than width . as such , fig7 illustrates enclosure 12 &# 39 ; which has wall adjustment means shown as adjustable side walls 18 &# 39 ;. side wall slot and wingnut combinations 39 allow the side walls to move in or out , as shown by arrows a , to overlie different lengths of barbecue housings . with the above variation , vent means shown as exhaust outlets 41 may be used in place of the vent ducts . such outlets extend through back wall 16 &# 39 ; adjacent base 34 . alternatively , fig1 - 13 illustrate a different wall adjustment means shown as sliding baffle 44 . the baffle is used to overlie portions of a barbecue grate not covered by the enclosure . in this embodiment , fasteners 45 extend through baffle slots 46 and adjustably secure the baffle to spaced - apart bosses 47 on side wall 18 . the baffles may be on either or both of the opposing side walls . they move laterally as shown by arrows b in fig1 to prevent heat loss and deflect the hot gases into the flues 26 . although not specifically shown , it will be appreciated that both of the above - described wall adjustment means could be used with back wall 16 . this would allow the enclosure to accommodate variations in barbecue width . with reference to fig8 and 9 , a modified interior cooking assembly 23 &# 39 ; is illustrated for use with barbecue units having a profiled housing h &# 39 ;. as shown , such housings typically include an open top with a front cut - out portion 50 . enclosures 12 &# 34 ; for the above housings commonly have back wall vent systems shown as offset vent opening 52 . to position the base adjacent the vent opening , a rear lip flange 54 is used to support the base back end portion on the barbecue housing back edge . a front pedestal flange 56 supports the base front end portion upon grating g . the pedestal flange has sufficient height to support the base in a level manner between partitions 24 &# 39 ;. for convenience , the partitions may include handle means shown as hand openings 58 . to facilitate an even distribution of hot gases and a controlled exit of cooled gases , a back partition 60 may be used . the back partition connects with side partitions 24 &# 39 ; to form a 3 - sided cooking chamber 36 . it includes exhaust outlets 41 &# 39 ; which are adjacent base 34 . the outlets communicate with the offset vent opening 52 for exiting the cooled gases in a natural convection fashion . fig1 - 16 illustrate a cooking assembly 23 &# 34 ; similar to the fig8 - 9 embodiment , but with additional venting means . base 34 is supported horizontally by rear lip flange 54 &# 39 ; and front pedestal flange 56 &# 39 ;. as before , the lip flange engages the housing back edge and the pedestal flange is supported by grating g . the back partition 60 &# 39 ; forms a 3 - sided cooking chamber with side partitions 24 &# 34 ;. the venting means include exhaust outlets 41 &# 34 ; which extend through the back partition and communicate with offset vent opening 52 &# 39 ; of enclosure 12 &# 39 ;&# 34 ;. the side partitions also include venting means shown as vent apertures 62 . such apertures extend through the lower portion of each side partition adjacent the base . they open into a side duct 64 which overlies the apertures on the outside of each partition . the ducts form enclosed passageways which communicate with vent openings 52 &# 39 ; for exhausting the cooled gases from cooking chamber 36 . the above arrangement may be useful for larger capacity cooking assemblies or where greater circulation of gases are desired . of course in the above and all other embodiments , temperature and gas flow is also controllable by regulation of the heat source . while the invention has been described with respect to preferred embodiments , it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention . accordingly , it is to be understood that the invention is not to be limited by the specific illustrative embodiments , but only by the scope of the appended claims .
the cooking assembly directs initial hot gases from a heat source against a heat semiconductive base . it then guides the gases to flues behind partitions that define sides of a cooking chamber . the gases flow over the partitions , down past food to be cooked , and then out vents . a uniform temperature distribution is achieved in the cooking chamber . the cooking assembly can be a barbecue cooker .