Abstract:
An electric oven includes a cabinet within which is arranged an oven cavity. Arranged below a bottom portion of the oven cavity is a combination convection/radiant bake cooking system adapted to derive heat energy from a single heat source. The oven preferably includes a central opening in the bottom portion within which is arranged a glass panel. Arranged about a periphery of the central opening are a plurality of vented openings adapted to introduce a convective airflow into the oven cavity. The glass panel provides both a conductive heat surface transmitting radiant heat energy into the oven cavity and a viewing surface allowing a consumer to view the operation of the heat source.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of cooking appliances and, more particularly, to an electric oven having a combination radiant/convection cooking system employing a common heat source located outside an oven cavity. 
     2. Discussion of the Prior Art 
     In general, electric ovens utilizing combination convection and radiant heat systems to perform a cooking process are well known in the art. In a typical arrangement, the convection system includes a fan assembly and an electric heat source arranged within a housing mounted either behind or above an oven cavity. In addition, a separate, radiant bake element is generally located in a lower region of the oven cavity. In order to achieve a combination radiant/convection cooking process, two distinct heating systems are employed to deliver heat into the oven cavity. 
     While utilizing two distinct systems to perform a cooking process has proven effective, there are several, associated disadvantages. Foremost, separate heating systems add to the overall complexity and cost of the oven. Increasing the number of heating elements increases the number of potential failure points in the system. Additionally, locating the systems in different regions of the electric oven requires routing supply and control wiring throughout substantial portions of the appliance. Separate heating systems also require additional space for ducting which, with modern systems, can limit the potential for adding other advantageous features to the oven. In the highly competitive field of household appliances, lowering production/sale costs, reducing the frequency of repair, and providing space for additional features will increase the attractiveness of the appliance to a consumer. 
     Finally, positioning the radiant bake element in the lower region of the oven cavity raises several other concerns. Mounting the bake element in an exposed portion of the oven cavity may lead to breakage caused by exposure to falling pans, dishes or the like. Additionally, food by-products released from cooking food items can accumulate on exterior surfaces of the element and, as a result, shorten the overall operational life of the element. Other problems arise when the element is mounted below a panel or false bottom in the oven cavity. Without being able to view the element in operation, i.e., see the element glow, a consumer may not be aware that the element has failed. When two distinct systems are in use, the consumer may mistakenly believe that the cooking process is being performed with heat derived from both systems when, in actuality, the heat is being supplied solely from one system or the other. If this was to occur, the quality of the cooking process would be reduced and, left unaware, the consumer may not know that a repair was necessary. 
     Based on the above, there exists a need in the art for a combination radiant/convection electric oven which utilizes a single heat source for both radiant and convection cooking. Moreover, there exists a need for an oven that positions the heat source in a manner which protects the heat source from exposure to a harsh oven environment, while enabling the consumer to view the heat source in operation. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a combination radiant/convection electric oven including a cabinet within which is arranged an oven cavity. Specifically, the oven includes a combination convection/radiant bake cooking system having an electric heating element and a convection fan or blower assembly arranged below a bottom wall of the oven cavity. More specifically, the electric heating element includes a central portion within which is positioned the convection fan. With this arrangement, the electric heating element serves as both a radiant heat source and as a convective heat source for the cooking system. 
     In accordance with a preferred embodiment, the cooking system is positioned below a central opening formed in the bottom wall of the oven cavity. A glass panel is positioned in the central opening. A plurality of convection air vents are also provided in the bottom wall to direct a convective airflow from the cooking system to the oven cavity. In the most preferred embodiment, the glass panel is formed from CERAN glass which enables at least a portion of the heat energy generated by the electric heating element to be introduced into the oven cavity in the form of radiant heat which combines with the convection heat flow to perform an overall cooking process. In further accordance with this preferred embodiment, the CERAN glass constitutes a window through which a consumer can view the heating element in operation. 
     Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an oven range incorporating a combination radiant/convection cooking system constructed in accordance with the present invention; and 
     FIG. 2 is a partial cross-sectional view of the oven range of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to FIG. 1, a cooking appliance  2 , generally taking the form of a free-standing oven range, includes a cabinet  4  provided with a cooktop  7 . As illustrated, appliance  2  constitutes an electric oven such that cooktop  7  is provided with a plurality of electric heating elements  10 - 13 . At this point, it should be noted that although appliance  2  is shown to constitute a free standing electric range, the present invention is equally applicable to various other types of types of electric ovens, including slide-in ranges, wall ovens and the like. 
     In a manner known in the art, cooking appliance  2  includes a control panel  16 , an interior oven cavity  19  having a door  21  associated therewith, and a lower drawer or bin  24 . More specifically, drawer or bin  24  is adapted to be slid into and out of cabinet  4 , in order to access an interior storage compartment (not shown) arranged therein. Door  21  is adapted to pivot at a lower portion  27  to enable selective access to within oven cavity  19 . In a manner also known in the art, door  21  is provided with a transparent zone  38  for viewing oven cavity  19  while door  21  is closed. In the embodiment shown, oven cavity  19  includes at least a top panel  31 , a bottom panel  32 , opposing side panels  33  and  34 , and a rear panel  35  (see FIG.  2 ). Arranged on side panels  33  and  34  are a plurality of vertically spaced and fore-to-aft extending baking rack support elements  37  for slidably receiving a food support rack (not shown). 
     A plurality of control knobs  42 - 45 , for use in selectively activating and deactivating heating elements  10 - 13  respectively, are arranged on a front face portion  48  of cabinet  4 . The heating of oven cavity  19  is preferably, electronically controlled, with control panel  16  including a display zone  51 , as well as a set of control buttons  54 - 57  which enable a consumer to select a desired cooking operation, e.g., bake, convection bake, broil, or keep warm operations. In addition, an operational mode cancel button  58 , a light activation button  59 , and a self-clean button  60  are provided on one side of display zone  51 . On the opposing side of display zone  51 , there is provided an operating set button  62 , a timer button  63 , cook and stop time buttons  64  and  65 , a clock button  66 , and a numeric pad  68 . 
     In general, the structure described above with respect to cooking appliance  2  is already known in the art and does not constitute part of the present invention. Therefore, this structure has only been described for the sake of completeness. Instead, the present invention is particularly directed to a combination radiant/convection cooking system adapted to establish a heated cooking environment within oven cavity  19 . 
     Referring to FIGS. 1 and 2, bottom panel  32  of oven cavity  19  includes a central opening  80 . In the embodiment shown, central opening  80  is defined by an interior ledge portion  82  which supports a removable glass panel  86 . More specifically, glass panel  86  is formed from a heat resistant, substantially transparent material, preferably a high temperature ceramic material such as CERAN. However, other materials having similar qualities are equally acceptable. Although the actual size and shape of opening  80  could vary, the preferred embodiment provides for a 12 inch×12 inch (approximately 30.5 cm×30.5 cm) opening  80 . 
     Along a front peripheral portion of central opening  80 , bottom panel  32  includes a downward and forward sloping portion  95  that leads to an upward and forward sloping portion  96 . With this construction, a front depression (not separately labeled) is defined forward of central opening  80 . Arranged in this front depression, specifically along sloping portion  96 , are a plurality of front vent openings generally indicated at  98 . Similarly, extending along a rear peripheral portion of central opening  80  is a downward and rearward sloping portion  103  that leads to an upward and rearward sloping portion  104 . In a manner similar to that illustrated for sloping portion  95 , a rear depression (not separately labeled) is formed in bottom panel  32  and a plurality of rear vent openings  106  are provided in sloping portion  104 . 
     As best shown in FIG. 2, a heating chamber  120 , having at least a bottom wall portion  125  and opposing front and rear wall portions  127  and  128 , is secured to bottom panel  32  of oven cavity  19  through attachment flanges  132  and  133 . Positioned within heating chamber  120  is a heating system  135  which, when activated, generates heat to be delivered into oven cavity  19 . In the embodiment shown, heating system  135  includes a single electric heat source  140  having a lower portion  141  mounted on bottom wall portion  125  of heating chamber  120 , and an upper portion  142  extending to bottom panel  32  of oven cavity  19 . Lower portion  141  and upper portion  142  combine to define an interior central cavity or zone  144  having a plurality of laterally spaced, front and rear exit ports  145  and  146  respectively. In a preferred form of the invention, electric heat source  140  constitutes a high wattage heat block. However, other types of heaters, including standard sheathed electric resistance elements, as well as quartz elements of various wattage levels, could be employed. In accordance with this preferred embodiment, electric heat source  140  serves as both a source of radiant heat energy and, as will be detailed more fully below, a source of convective heat energy. 
     As indicated above, heating system  135  of cooking appliance  2  also includes a convective cooking system  146  which can be activated to perform a portion of an overall cooking process. As shown, convective cooking system  146  includes a fan motor  148  operatively connected to a blower  149  through a motor shaft  150 . Fan motor  148  is positioned within an air intake plenum  160  defined by a basin  162  affixed to bottom wall portion  125 . Air intake plenum  160 , which includes a plurality of air inlet ports generally indicated at  165 and  166 , enables an incoming airflow to be directed into heating chamber  120  through a heating chamber inlet openings  170  arranged adjacent blower  149 . 
     Having described a preferred construction of cooking appliance  2 , a preferred method of operation will now be described. Assuming a combination bake/convection cooking operation is selected through control panel  68 , electrical current is supplied to electric heat source  140 . Upon activation, the temperature of electric heat source  140  begins to rise, resulting in a glowing effect which is visible through glass panel  86 . As the temperature of heat source  140  rises, heat energy, generally indicated at B, is radiated into oven cavity  19  through bottom panel  32  and glass panel  86 , thereby establishing a heated environment suitable to perform the desired cooking process. 
     Simultaneously, electrical energy is supplied to fan motor  148 , thereby rotating blower  149  which develops convective air streams generally indicated at A. In addition to the radiant heat energy, electric heat source  140  supplies convective heat energy to convective air streams A. More specifically, as fan motor  148  operates, an incoming airflow C is drawn into intake air plenum  160  through the plurality of inlet ports  165  and  166 . The incoming airflow C is subsequently drawn into interior portion  144  of electric heat source  140  through intake openings  170  where heat energy from electric heat source  140  is transferred, through a convective heat process, to the incoming airflow C to establish convective air streams A. At the same time, blower  149  drives convective air streams A from interior cavity  144  of electric heat source  140  through the plurality of exit ports  145  and  146 . The convective air streams A travel into heating chamber  120  and, finally, into oven cavity  19  through front and rear inlet vent openings  98  and  106 . In this manner, food item(s) placed in oven cavity  19  will be subjected to a combination radiant bake and convection cooking process. By employing both the radiant and convective heat operations, a uniform cooking environment is established and the cooking process can be performed in less time. Due to the locating of inlet vent openings  98  and  106  on sloping portions  96  and  104  respectively, the convection airflow is directed upward and centrally in oven cavity  19  in a manner which enhances the overall convection cooking process. 
     Although described with reference to a preferred embodiment of the present invention, it should be readily apparent to one of ordinary skill in the art that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, while the convective air inlet vent openings are shown extending adjacent front and rear portions of the glass panel, other arrangements, including having the vents extend entirely about or through the glass panel, could be employed. For instance, it would be possible to have substantially the entire bottom wall of the oven cavity defined by a glass plate with vent openings therein. In addition to radiant and convection cooking, a microwave system could be added to further reduce the overall time required to perform the cooking operation or to simply add additional versatility to cooking appliance  2 . In general, the invention is only intended to be limited to the scope of the following claims.