Patent Abstract:
A rotisserie convection oven including a rotatable drum assembly which allows cooking of food items therein without added cooking oils is disclosed. The present oven is designed for cooking of pre-prepared or frozen foods with minimal ingestion of cooking oils and residual oil byproducts of concern to the health-conscious consumer. The present oven provides a countertop appliance having an enclosed cooking chamber with tubular heating elements wherein a rotatable drum containing foodstuffs is coupled to a rotisserie drive assembly. An integrated control chamber protects electrical components and encloses a convection fan assembly which is disposed in air transfer communication with the cooking chamber to enable circulation of air across the heating elements and through the rotatable drum during the cooking cycle. In one embodiment the rotatable drum is constructed of wire mesh to permit the continuous circulation of heated air therein to reduce cooking temperatures and shorten the cooking cycle.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to household appliances and, more particularly, to a rotisserie convection oven including a rotatable cooking drum and method of use, which allows cooking of pre-prepared and frozen foods within such cooking drum with minimal ingestion of cooking oils and cooking oil byproducts in the food items, which is of concern to the health-conscious consumer. 
         [0002]    Portable kitchen countertop ovens with rotisserie mechanisms for cooking food items such as chicken, turkey, roasts and other foodstuffs are known in the prior art. However, such ovens typically utilize a gear driven bar and spit assembly having sharp spit rods whereon the food item is skewered and then placed in the oven for cooking. Such prior art countertop ovens are known to provide rotary cooking containers comprising a housing which is mounted on the rotisserie spit rods to support and rotate the container. Such prior art ovens often utilize tubular heating elements mounted within the cooking chamber of the oven for cooking. Tubular heating elements are constructed from metallic tubing wherein an electrical resistance heating wire is enclosed, which function to radiate heat for cooking within the cooking chamber. The tubular heating elements are normally disposed on the back and/or bottom walls of the cooking chamber and may provide Low and High heat settings for cooking. 
         [0003]    Such a rotary drum for attachment to a prior art rotisserie mechanism has numerous disadvantages. Initially, mounting the rotating drum on a gear driven rotisserie mechanism commonly requires adapting the rotary drum to existing spit rod hardware which necessitates the fabrication of additional components and increased manufacturing complexity and costs. 
         [0004]    In addition, such a prior art rotisserie oven typically includes a rotating basket or an enclosed rotary housing wherein the food items are disposed with added cooking oil and seasonings to effectively baste and stir fry the food items which become saturated with oil during the cooking process thereby adding to the heated cooking oil byproducts ingested by the user. 
         [0005]    Further, such a prior art rotisserie oven typically provides only a single, enclosed cooking chamber wherein the food items are rotated in proximity to a radiant heating element without circulating heated air within the cooking chamber by convection to ensure a more uniform and efficient cooking process of shorter duration. 
         [0006]    Thus, the rotisserie convection oven with a rotatable cooking drum of the present invention has been developed to solve these problems and other shortcomings of the prior art. 
       DESCRIPTION OF THE PRIOR ART 
       [0007]    U.S. Pat. No. 8,017,167 issued on Sep. 12, 2011, entitled Food Cooking Basket for A Rotisserie Oven discloses a portable oven with a rotisserie mechanism that accommodates a food basket and/or a rotary cooking container. Such cooking container is mounted on the rotisserie spit rod assembly to support and rotate the cooking container, which is a solid-walled (i.e. non-perforated) container designed to retain cooking oils and marinade for cooking food items. This oven utilizes an array of tubular heating rods mounted at the back wall of the cooking chamber of the oven, which can be selectively energized for radiant heating only. This rotisserie oven does not provide a perforated, rotating drum for circulation of heated air by convection through the rotating drum to ensure a uniform cooking process. 
         [0008]    U.S. Pat. No. 7,973,264 issued on Jul. 5, 2011, entitled Toaster Oven with Low-Profile Heating Elements, by the same inventor named herein, discloses an optional rotisserie mechanism and a convection fan to reduce cooking temperature and to shorten cooking cycles. However, this patent does not disclose a rotatable cooking drum of perforated construction wherein foodstuffs are contained for cooking. 
         [0009]    While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not disclose the portable convection oven of the present invention including a rotating drum wherein heated air circulates to enhance the cooking process. 
       SUMMARY OF THE INVENTION 
       [0010]    Accordingly, the present invention is a rotisserie convection oven including a rotatable cooking drum which allows cooking of food items at lower cooking temperatures and shorter cooking cycles thereby eliminating the need for added cooking oils and marinades. The present oven is designed for cooking of pre-prepared or frozen foods such as French fries, fish sticks, chicken nuggets and other foodstuffs resulting in minimal ingestion of cooking oils, grease and cooking derived byproducts of concern to the health-conscious consumer. 
         [0011]    The present rotisserie convection oven provides a kitchen countertop appliance which features an enclosed cooking chamber wherein a rotatable drum is detachably engaged with a rotisserie drive mechanism. The rotisserie drive motor and a convection fan are positioned in a protected control chamber disposed in air transfer communication with the cooking chamber to enable the circulation of heated air within the cooking chamber, which circulates through the rotating drum during the cooking cycle. 
         [0012]    The present rotisserie convection oven provides a rotatable cooking drum which features both end-loading and side-loading of foodstuffs in alternative embodiments for the convenience of the user. The present rotatable cooking drum comprises a food container having a perforated cylindrical wall and/or perforated end caps permitting the circulation of heated air by the convection fan through the rotating drum to maximize cooking efficiency. A plurality of tubular heating elements disposed at predetermined locations within the cooking chamber can be selectively energized and cycled On and Off during the cooking cycle. An interior weir bar or baffle interrupts the continuous tumbling of food items in operation for maximum exposure to the heating elements. The present invention also provides a tool for removing the rotatable drum from the hot oven for the user&#39;s convenience. 
         [0013]    There has thus been outlined, rather broadly, the important features of the present invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
         [0014]    Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
         [0015]    Other features and technical advantages of the present invention will become apparent from a study of the following description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The novel features of the present invention are set forth in the appended claims. The invention itself, however, as well as other features and advantages thereof will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures, wherein: 
           [0017]      FIG. 1  is a perspective view of the rotisserie convection oven of the present invention; 
           [0018]      FIG. 2A  is a perspective view of the present oven wherein the front door thereof is in an open position showing further details thereof; 
           [0019]      FIG. 2B  is a right side elevation view of the present oven wherein the outer wall has been removed for clarification; 
           [0020]      FIG. 3  is a longitudinal cross-section taken along the section line  3 - 3  of  FIG. 2A  of the present oven showing further details thereof; 
           [0021]      FIG. 4  is a perspective view of the cooking chamber of the present oven wherein the outer housing and door have been removed for clarification; 
           [0022]      FIG. 5  is an exploded perspective view of the components within the present cooking chamber showing further details thereof; 
           [0023]      FIG. 6A  is an exploded perspective view of one embodiment of the rotatable drum of the present invention designed for end-loading; 
           [0024]      FIG. 6B  is an exploded perspective view of another embodiment of the rotatable drum of the present invention designed for side-loading; 
           [0025]      FIG. 7A  is a perspective view of another embodiment of the rotatable drum of the present invention designed for end-loading; 
           [0026]      FIG. 7B  is a perspective view of another embodiment of the rotatable drum of the present invention designed for side-loading; 
           [0027]      FIG. 8A  is a perspective view of a drum removal tool of the present invention; 
           [0028]      FIG. 8B  is a perspective view of a drum removal tool engaged with the rotatable drum illustrated in  FIG. 6A ; and 
           [0029]      FIG. 9  is a schematic representation of the electrical components and circuitry of the present rotisserie convection oven. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    With further reference to the drawings there is shown therein an embodiment of a rotisserie convection oven with a rotatable cooking drum in accordance with the present invention, indicated generally at  10  and illustrated in  FIG. 1 , although it will be appreciated that the present invention is not limited in scope to this embodiment. The present oven  10  is comprised of an outer housing, indicated generally at  20 , including a front door assembly, indicated generally at  25 , which further includes a viewing window  36  and a door handle  27  for opening and closing door. 
         [0031]    More particularly, outer housing  20  further comprises a front panel  21 , top side  23 , base  24 , side walls  26 ,  28  and back wall  22  ( FIG. 2A ). The base  24  of housing  20  is provided with a plurality of feet  32  ( FIG. 2B ), which support the present oven  10  on a kitchen countertop or other working surface. 
         [0032]    A temperature control selector switch  17   a,  a function control selector switch  18   a  and a timer control switch  19   a  are disposed on panel  21  of housing  20  to operate the respective heating controller  17 , function controller  18  and timer  19  components and circuitry ( FIG. 2B ) to regulate the functions of the oven  10 . An indicator light  15  on the front panel  21  is provided for the user&#39;s safety and convenience signaling that a cooking cycle is in progress.  FIG. 2B  also shows the position of the rotisserie drive assembly, indicated generally at  60  and the convection fan assembly, indicated generally at  70  as described hereinafter in further detail. 
         [0033]    In an alternative embodiment of the present oven, a digital control panel (not illustrated) including a touch-screen interface with an integrated control circuit board, which is known in the prior art can be utilized to regulate the functions of the oven. 
         [0034]    As further illustrated in  FIGS. 3 and 4 , a cooking chamber  40  comprises opposite sidewalls  41 ,  42 , back wall  22 , and top surface  45  wherein a rotatable drum assembly, indicated generally at  75 , is detachably engaged. Chamber sidewalls  41 ,  42  are disposed in parallel to housing sidewalls  26 ,  28 . Chamber top surface  45  is disposed in parallel to housing base  24  and top side  23  of housing  20  respectively. In the embodiment shown housing back wall  22  defines both the back of housing  20  and also the back of chamber  40  to simplify construction. Similarly, an upper surface of housing base  24  defines both the bottom of housing  20  and the bottom of cooking chamber  40  to simplify construction. 
         [0035]    Housing sidewall  28 , top wall  23 , base  24 , sidewall  42  and a portion of housing back wall  22  including vents  22   a  define a control chamber, indicated generally at  90  ( FIG. 3 ). Control chamber  90  encloses the rotisserie drive assembly  60  including a rotisserie motor  68  including electrical circuitry, driveshaft  63 , coupling  59  and stub axle  58 , which engages and rotates drum assembly  75 . It can be seen that control chamber  90  also encloses convection fan assembly  70  including a fan impeller  65 , fan motor  62  including electrical circuitry and fan housing  61 . 
         [0036]    Still referring to  FIG. 3  it will be appreciated the present oven  10  includes three pairs of horizontally disposed heating elements  52 ,  54 ,  56  which are arranged as shown within the cooking chamber  40 . In this embodiment heating elements  52 ,  54 ,  56  are mounted in close proximity to back  22 , base  24  and top surface  45  of chamber  40  ( FIG. 4 ) in parallel relation and positioned in spaced-apart relation thereto. 
         [0037]    In the embodiment shown in  FIGS. 3 and 4 , heating elements  52 ,  54 ,  56  are tubular type heating elements such as those manufactured under the trade name, CAL-ROD® or other suitable heating elements for this application. CALROD® heating elements  52 ,  54 ,  56  are typically comprised of stainless steel tubing, which encloses a resistance heating wire (not shown). Such CALROD heating elements  52 ,  54 ,  56  are well known in the appliance industry and further detailed description thereof is not deemed necessary. 
         [0038]    Heating elements  52 ,  54 ,  56  are electrically interconnected to the temperature controller  17 , function controller  18  and timer  19  ( FIG. 2B ) to regulate the cooking functions of the oven  10 . Heating elements  52 ,  54 ,  56  can be selectively energized by using temperature controller knob  17   a  and function controller knob  18   a  to activate each pair of heating elements separately or in combination to achieve the desired cooking temperature. Function controller  18  provides variable operating modes of the convection motor  62  and rotisserie motor  68  in conjunction with the heating elements  52 ,  54 ,  56  corresponding to “Broil, Convection, Bake, Rotisserie and Fryer” as illustrated in the electrical schematic in  FIG. 9 . 
         [0039]    In a method of the present invention, cooking by convection occurs when the convection function is selected using controller  18  and heated air within oven  10  is forced into the cooking chamber  40  by fan impeller  65  on its output side via outlet vents  64 ,  66  ( FIG. 5 ) and is circulated about the cooking chamber. As illustrated in  FIG. 3 , fan impeller  65  draws heated air (on its suction side) from cooking chamber  40 , which passes through perforations  77  ( FIG. 5 ) formed in the end caps  75   a,    75   b  of the rotating drum  75  as shown by directional arrows  80 . Drawn by fan impeller  65  heated air passes through rotating drum  75  heating food items contained therein and exits via end cap  75   b  ( FIG. 6A ) passing into air duct  67  via intake vent  69  ( FIG. 5 ). 
         [0040]    Fan impeller  65  (from its output side) continuously redirects the flow of heated air from duct  67  back into the cooking chamber  40  via outlet vents  64 ,  66  as shown in  FIG. 3  by directional arrows  85 . Air is circulated around heating elements  52 ,  54 ,  56  where it is reheated and again passes through the rotating drum  75  via perforations  77  ( FIG. 5 ) and is drawn into inlet vents  69  on the suction side of the fan impeller  65 . By continuously circulating heated air over a tumbling food item positioned within rotatable drum  75 , the present oven  10  can operate at a lower temperature and cook food items more quickly than a comparable prior art rotisserie oven without convection heating. 
         [0041]    In one embodiment shown in  FIG. 6A , a drum assembly  75  of the end-loading type comprises a generally cylindrical body member  76  being fabricated of sheet metal whereon end caps  75   a  ( FIG. 5 ),  75   b  having a plurality of perforations  77  are attached. At least one of such end caps  75   b  is removable from the body member  76  by use of operated clamps  86  in order to load pre-prepared or frozen foods such as French fries, fish sticks, chicken nuggets and other similar foodstuffs into the drum assembly  75  for cooking. 
         [0042]    In an alternative embodiment a drum assembly  75 ′ of the side-loading type shown in  FIG. 6B  comprises a hinged body  76 ′ including upper and lower semi-cylindrical halves  76   a ′,  76   b ′. End caps  75   a ′,  75   b ′ each having a plurality of perforations  77  formed therein are permanently attached to lower body half  76   b ′ by weldment. Body halves  76   a ′,  76   b ′ are connected by a section of piano hinge  71  along the adjacent back edges thereof. The opposite front edge of body halves  76   a ′,  76   b ′ are secured in place by use of friction latches  96  integrated with a handle  97  (as more clearly shown in  FIG. 7B ). Latches  96  engage mating catches  96   a  installed on the front edge of lower body half  76   b ′ and are opened by manual pressure in order to load pre-prepared or frozen foods and other similar foodstuffs in the drum assembly  75 ′ for cooking. 
         [0043]    Referring to  FIG. 7A  there is shown another embodiment of rotatable drum assembly  75 ″ of the end-loading type comprising a generally cylindrical body member  76 ″ being fabricated of wire mesh or expanded sheet metal whereon end caps  75   a ″,  75   b ″ having a plurality of perforations  77  are attached by weldment. Similarly, at least one of such end caps  75   b ″ is removable from the body member  76 ″ by use of clamps  86  in order to load foodstuffs into the drum assembly  75 ″ for cooking. 
         [0044]    Another alternative embodiment of a rotatable drum assembly  75 ′ of the side-loading type shown in  FIG. 7B  comprises a hinged body  76 ′″ including upper and lower semi-cylindrical halves  76   a ′″,  76   b ′″ fabricated of air permeable, wire mesh or expanded sheet metal. End caps  75   a ′″,  75   b ′″ each having a plurality of perforations  77  formed therein are permanently attached to lower body half  76   b ′″ by weldment. Body halves  76   a ′″,  76   b ′″ are connected by a section of piano hinge  71  along the adjacent back edges thereof and secured by weldment. The opposite front edge of body halves  76   a ′″,  76   b ′″ are secured in place by use of friction latches  96  integrated with a handle  97 . It can be seen that body halves  76   a ′″,  76   b ′″ each includes at least one reinforcing strip  79  fabricated of sheet metal to provide structural support for handle  97 , latches  96  and mating catches  96   a  and to shield the edges off the wire mesh material. Latches  96  engage mating catches  96   a  installed on the front edge of lower body half  76   b ′″ and are opened by manual pressure in order to load pre-prepared or frozen foods and other similar foodstuffs in the drum  75 ′″ for cooking. 
         [0045]    It can be seen that each drum assembly  75 ,  75 ′,  75 ″,  75 ′″ includes an interior weir bar or baffle  74  that is permanently attached to and extends the length thereof in parallel relation to axis—A—( FIG. 6A ). Baffle  74  is designed to briefly hold a food item in position as such food item rotates past a given pair of heating elements  52 ,  54 ,  56 . That is, baffle  74  momentarily interrupts or delays the continuous tumbling of foodstuffs during rotation of a drum assembly  75 ,  75 ′,  75 ″,  75 ′″ in the rotisserie mode. Such an interruption in the normal tumbling of foodstuffs within a rotating drum assembly  75 ,  75 ′,  75 ″,  75 ′″ has been observed to provide maximum exposure of food items to heating elements  52 ,  54 ,  56  in operation enabling more efficient cooking and shorter cooking cycles. 
         [0046]    As seen in  FIG. 6A  a stub axle  58  having a square cross-section projects from mating coupling  59  ( FIG. 5 ) through a hole  55  formed in cooking chamber side wall  42 . Coupling  59  ( FIG. 5 ) includes a square coaxial opening  59   a  that is dimensioned to a slip fit condition with stub axle  58 . At an opposite end coupling  59  engages mating driveshaft  63  ( FIG. 3 ) extending from the rotisserie motor  68 . Stub axle  58  is received in a mating receptacle in the end cap  75   b  to drive the drum assembly  75  during operation in the rotisserie mode. 
         [0047]    An opposite end cap  75   a  of drum assembly  75  receives an extension shaft  78  having a round cross-section ( FIG. 6 ). Extension shaft  78  is received at its proximal end in a mating receptacle (not shown) in the end cap  75   b  to enable rotation of drum assembly  75  in operation. A distal end of extension shaft  78  includes a groove  79 , which engages a mating bracket  47  having a slot  47   a  adapted to receive groove  79  on the extension shaft ( FIG. 5 ). Bracket  47  is mounted with a fastener (not shown) on a side wall  41  of the cooking chamber  40  ( FIG. 3 ) in alignment with axis—A—of drum assembly  75  and rotisserie drive assembly  60  to ensure rotation with minimal friction. 
         [0048]    Both stub axle  58  and extension shaft  78  include a tool groove  58   a,    78   a  respectively for engagement of drum removal tool, indicated generally at  100 , ( FIGS. 8A-8B ) which allows the user to remove drum assemblies  75 ,  75 ′,  75 ″,  75 ′″ after a cooking cycle has been completed. Tool  100  is a generally U-shaped in configuration being fabricated from a heavy gauge wire or other suitable material. Tool  100  comprises a cross-member  105  having integrally formed, perpendicular arm members  102 ,  103 . The distal ends of each arm member  102 ,  103  are bent into J-shaped hook portions  102   a,    103   a  as shown in  FIG. 8A . A handle  103  for tool  100  is fabricated from a heat-resistant material and is fixedly attached to a midpoint of cross-member  105  for the user&#39;s convenience. It will be appreciated that cross-member  105  and arm members  102 ,  103  are configured such that hook portions  102   a,    103   a  engage tool groves  58   a,    79   a  formed in the stub axle  58  and shaft  78  respectively as illustrated in  FIG. 8B . Thus, tool  100  enables the user to lift and remove a loaded drum assembly  75 ,  75 ′,  75 ″  75 ′″ from oven  10  when the drum assembly is too hot for direct manual contact by the user. 
         [0049]    The electrical functions of rotisserie oven  10  can be carried out by the standard electromechanical controls as described hereinabove. Alternatively, the electrical functions of the rotisserie convection oven may be carried out by an electronic control panel (not shown) having a touch-based interface with an integrated control circuit board. 
         [0050]    Referring to  FIG. 9  there is shown therein a schematic representation of the electrical components and circuitry of the present rotisserie convection oven  10 . Function controller  18  is electrically interconnected with timer  19 , temperature controller  17 , convection fan motor  62 , rotisserie drive motor  68  and heating elements  52 ,  54  and  56 . Function controller  18  provides variable operating modes of the convection motor  62  and rotisserie motor  68  in conjunction with the heating elements  52 ,  54 ,  56 . 
         [0051]    Heating elements  52 ,  54 ,  56  can be selectively energized by using temperature control selector switch  17   a  and function control selector switch  18   a  to activate each pair of heating elements separately or in combination to achieve a desired cooking mode (i.e. Broil, Convection, Bake, Rotisserie and Fryer modes) as understood by reference to the schematic drawing of  FIG. 9 . 
         [0052]    With reference to electrical specifications, the wattage rating for the present rotisserie convection oven  10  can vary up to 1800 watts depending upon the selected function of the oven. 
         [0053]    The present oven  10  is designed for use with standard residential electrical systems. An electrical cord and plug (not shown) are also provided to connect the present rotisserie convection oven  10  with a standard electrical outlet. 
         [0054]    In accordance with the present invention the drum assemblies  75 ,  75 ′,  75 ″,  75 ′″ can be configured to fit various common sizes of commercially available rotisserie ovens and are suitable for retrofitting to such prior art rotisserie ovens to permanently replace conventional rotating baskets and rotisserie bar and spit assemblies. 
         [0055]    Although not specifically illustrated in the drawings, it should be understood that additional equipment and structural components will be provided as necessary and that all of the components described above are arranged and supported in an appropriate fashion to form a complete and operative Rotisserie Convection Oven with Rotatable Drum incorporating features of the present invention. 
         [0056]    Moreover, although illustrative embodiments of the invention have been described, a latitude of modification, change, and substitution is intended in the foregoing disclosure, and in certain instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of invention.

Technology Classification (CPC): 0