Abstract:
A cooking structure which provide for two or more side-by-side ovens separated by vertical, movable, hinged partition(s) whereby the oven structure may function as one large oven or as two or more smaller independent ovens, wherein for each oven a tangential fan blows air substantially evenly over upper electrical heating elements strung generally from side-to-side of the oven, wherein a flow director (baffle) structure functions as a radiant heat shield which is operator movable to either expose to or occlude from the oven cooking chamber the direct radiation from its heating elements, depending on the need to roast, bake, or broil the food product. Also provided are lower electrical heating elements positioned below a ceramic cooking surface for ensuring evenness of radiant heat transfer therefrom. Also provided is operator controlled top vs. bottom heating using a slide control that reciprocally affects the duty cycle of the top and bottom electrical heating elements, further allowing precision baking control.

Description:
This application is a Continuation-in-Part of Applicant&#39;s application Ser. No. 11/347,982 filed Feb. 6, 2006 now abandoned and titled “COOKING OVEN”, and Applicant claims priority under 35 U.S.C. 119(e)(1) based on Applicants Provisional U.S. Patent Application Ser. No. 60/661,618 filed Mar. 14, 2005 and titled “CONCEPT DESIGN FOR COMMERCIAL STYLE HOME BAKING DEVICE/OVEN”, on Provisional 60/693,882 filed Jun. 24, 2005 titled “CONCEPT OVEN DESIGN”, and on Provisional 60/839,643 filed Aug. 23, 2006 and titled “COOKING OVEN”. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field 
     The present invention is directed to electrically heated convection baking ovens and the like and particularly concerns, in preferred embodiments, operator control of radiant heat emanating from heating elements and directed down into the oven cooking chamber, specially constructed and functional heated air circulating means for providing more uniform heat transfer throughout the cooking chamber, an upper heating element and a lower heating element with a ceramic or metal heat sink, specially designed partition or divider means for quickly and easily converting the oven cooking chamber from a single chamber to multiple chambers and vise versa, and in a most preferred embodiment uniquely functional electrical control means is provided for regulating heat output of the upper and lower heating elements in a reciprocal manner so as to accurately regulate the temperature of a particular are—sweet spot—within the oven cooking chamber which is most desirable for a particular product. 
     2. Prior Art 
     Conventional home ovens for the past 100 years have retained the basic cube configuration for the oven cooking chamber which is typically provided with horizontal interposed cooking racks. Other than the addition of “convection” provided by fan means and the substitution of electronic for electromechanical controls, little has changed. This basic configuration leaves considerable room for improvement. 
     Much oven usage involves baking, roasting or broiling of smaller size or number of food products whereby utilization of the large standard oven cavity becomes energy inefficient. Attempts at simultaneous precision baking on multiple racks is usually futile because of the unevenness in heat transfer excepting perhaps for ovens with “pure” or “European style” convection. Simply spoken, most ovens have one “sweet spot” or area that cooks with evenness and consistency for a specific product. Attempts have been made to “fine tune” this “sweet spot” by placing the racks at different heights, however, many conventional ovens still have a tendency to over cook or over brown the food product at the rear of the oven. This can be due to excessive air leaks in the oven door, excessive airflow over the product next to fan intake, or even opening the oven door multiple times to check on the product being baked. 
     SUMMARY OF THE INVENTION 
     The present invention, in one of its most preferred embodiments comprises an oven structure which provides for an oven unit comprising a single or multiple (any number) side by side ovens, wherein the multiple ovens are independently operable and are separated by generally vertical, hinged partition(s) whereby upon swinging one or more partitions back to adjacent the rear of one or more adjacent ovens the oven structure may then function as one or more large ovens, and which further provides for highly controlled heating of each cooking chamber by means of a tangential fan for each chamber with air flow therefrom directed over upper electrical heating elements by means of flow director structure ensuring laminar flow and evenness of heat transfers, wherein the flow director also functions as a radiant heat shield or occluder which is operator movable to either expose or occlude the radiant heat to each cooking chamber from the upper elements depending on the need to roast, bake, or broil the food product. Also provided are lower electrical heating elements positioned below ceramic cooking surfaces for ensuring evenness of radiant heat transfer therefrom. Also provided for is operator controlled top vs. bottom heating using a slide control that reciprocally affects the duty cycle of the top and bottom electrical heating elements, further allowing precision baking control. 
     The present oven structure design addresses the aforementioned prior difficulties and in addition, the design concept extends the side walls of the oven and diminishes the vertical oven height, and provides a hinged moveable vertical partition to enable the operator to vary the cooking chamber size for smaller or larger products. This allows for the oven to be employed as a single larger oven or as two or more smaller ovens. Also, independent controls for these partitioned cooking chambers enable the user to perform independent cooking tasks in each separate cooking chamber. 
     An even heat transfer is the hall mark of precision baking and is probably more important than the method of transfer (radiant, convective, conductive). This issue is addressed through the present invention by a number of changes or departures from the standard. For example, with the present invention, convective heat is provided by a tangential fan positioned in the rear top of the oven that blows air along its entire length. The inlet air is ducted to the fan from the bottom of the back wall of the cooking chamber and the outflow air is controlled by a flow director that channels the heated air along the top of the oven over the heating elements and down into the cooking chamber resulting in an even laminar air flow. 
     The flow director is constructed to function also as a radiant heat occluder to either block or expose the cooking product to direct radiant heat from the upper heating elements depending on the cooking task desired. For example, the air flow director can serve as a radiant shield for the top elements, thereby ensuring evenest in heating but can be repositioned to expose the top heating elements to the food product as would be necessary, for example for broiling. Bottom heat is provided by heating elements preferably beneath a large ceramic plate which forms the floor or bottom wall of the oven cooking chamber on which plate the food product may be placed either directly as with bread or indirectly as in a cooking vessel. The ceramic or metal plate functions as a heat sink and radiates heat evenly. A ceramic plate is preferred since it is a poor heat conductor and thus prevents burning of the bottom of the food product. 
     All of the above features of the present invention, in combination, ensure an even heat distribution to the food product. Also, the ultimate in precision baking is the ability to reciprocally adjust the heat delivery from upper and lower heating elements of each oven. This is accomplished by the present invention by means of, e.g., a slide switch (variable resistor) and an appropriate electrical circuit that increases or decreases the cycle time to the upper and lower heating elements in a reciprocal fashion. For example, adjusting the switch upwardly would concomitantly increase the duty cycle of the upper elements and decrease the duty cycle of the lower elements. Preset temperature would be maintained thereby but the top of the product would be exposed to more heat, much like moving the conventional oven rack up or down. Examples would be cooking a steak with the slide switch in the full up position with the heat being generated exclusively by the upper elements such as to effect broiling. In cooking a pizza for example, the switch would be far down to effectively brown the crust. 
     The present ovens can be mounted under shelf, or over the stove cooking surface with appropriate venting provided, or over the counter top. This makes the baking process more convenient in minimizing bending or stooping and allows the user to more easily produce the exact “brownness” of the cooked products especially breads, particularly where the provision of a large glass door enhances visualization. In this regard, ease of visualization is provided by the oven being just below eye level and by large transparent doors. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be understood further from the following description and drawings wherein certain structures are shown in exaggerated dimensions for purposes of clarity, wherein the figures are not in structural proportion to each other, wherein their structural appearance in the drawings does not, in any way, restrict their methods of manufacture, and wherein: 
         FIG. 1  is a frontal isometric view of the present oven with the oven divider or partition and front access door removed for clarity; 
         FIG. 2  is a cross-sectional view of a double oven taken along line  2 - 2  in  FIG. 1  with the oven partition means in place; 
         FIG. 2A  is a cross-section of an alternative mounting for the heat sink plate; 
         FIG. 3  is a cross-sectional view taken alone line  3 - 3  in  FIG. 2 ; 
         FIG. 3A  is an enlarged cross-sectional view of the dotted area in  FIG. 3 ; 
         FIG. 4  is an isometric cross-sectional view taken along line  4 - 4  of  FIG. 1  but rotated clockwise about 40°; 
         FIG. 4A  is a longitudinal cross-sectional view of a typical tangential fan; 
         FIG. 5  is a cross-sectional taken along line  5 - 5  in  FIG. 3  depicting circulating air flow paths and a non-blocking position of a portion of the occluder slide plate; 
         FIG. 6  is a cross-sectional view taken along line  6 - 6  in  FIG. 3 ; 
         FIG. 6A  is a view as in  FIG. 6  but showing air inlet  19 B positioned at the lower front portion of the oven; 
         FIG. 6B  is a top view of the heat sink plate of  FIG. 6A ; 
         FIG. 7  is an isometric plan view of the heat radiation shielding or blocking occluder slide plate of  FIGS. 5 and 6 ; 
         FIG. 8  is a cross-sectional view taken along the axis of a portion of the upper heating cavity and the axis of the two circulating fans showing a coaxial drive mechanism for selectively operating the separate fans; 
         FIG. 9  is a cross-sectional view as in  FIG. 8  showing a clutch type of driving means for the separate fans; 
         FIG. 10  is a variation of the clutch engaging faces of  FIG. 9 ; and 
         FIGS. 11 and 12  are schematic electrical circuits for operating the present oven structure by reciprocating balance of the heat output of the upper and lower heating elements. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings which represent the preferred and best mode for practicing the present invention, the various wall structures are shown as monolithic, however, fabrication in sections of these structures in conventional manner can be employed. As shown, the present cooking oven structure comprises a single ( FIG. 1 ) or side by side multiple ovens ( FIGS. 2-10 ), wherein each oven comprises spaced inner  10  and outer  12  metal housings formed respectively by first wall means  11  and second wall means  13 . First wall means  11  provides the structural elements of a ceiling  14 , a floor  18 , opposing side walls  22 ,  24 , a back wall  30 , and front wall portions  34  provided with a hinged access door  38 . 
     For each oven, the combination of an upper heating cavity  45  communicating with a circulating air feed channel generally designated  39  is formed (for oven “C” see  FIGS. 3 and 6 ) by side walls  22  and  24 , back wall  30  and ceiling  14  of first wall means  11 , by third wall means  41  having a generally horizontal upper section  43  spaced inwardly downwardly from ceiling  14  and having a generally vertical rear section  49  spaced inwardly forwardly from said back wall  30 , and by portion  103  of heat sink plate  44 . It is noted that the terms generally horizontal or generally vertical or the like as used herein are to be given wide latitude since the structures can be slanted or the like depending on design needs. 
     Similarly, for oven “D” with portion  103  ( FIG. 6 ) of heat sink plate  44  removed, channel  39  is formed by wall portions or sections  22 ,  24 ,  30 ,  49  and floor  18 . Similarly for the oven of  FIG. 6A , channel  39  is formed by wall portions or sections  22 ,  24 ,  30 ,  49  and then also by floor  18 . 
     The heat sink ceramic or steel plate means  44  is adapted to provide a predeterminable heat supply and is spaced upwardly from floor  18  and forms with wall means  11  a lower heating cavity  16 . Rear section  49  in oven “C” ( FIG. 3 ) is spaced upwardly from plate means  44 , e.g., 0.5-2.0 in. to provide a circulating air outlet  19  to channel  39 . In oven “D”, air outlet  19 A to channel  39  is preferably provided by removing the inner portion  103  ( FIG. 6 ) of plate  44  in order to allow partition  79  to swing to its full open position adjacent wall  41  to form a single enlarged oven without impeding air flow into channel  39 . These structural elements of the inner housing, third wall means  41  and ceramic heat sink plate define the cooking chambers  40 . 
     In  FIG. 6A , circulating air outlet  19 B to channel  39  being positioned at the front portion of all ovens in the group, e.g., “C” and “D”, allows the air to circulate all the way to the front of the cooking chambers as well as over the lower heating elements thereby diminishing typical, cold spots near the oven front and whereby air flow is in contact with both upper and lower heating elements which thereby further improves heat transfer and heating efficiency. Such outlet  19 B can be provided by simply removing a lateral front portion, e.g., 0.5-2.0 in. of plate  44 , or by slotting the plate, e.g., 0.5-2.0 in. wide, substantially all the way across a front portion of the plate as shown in  FIG. 6B , both alternatives as well as outlets  19  and  19 A and other equivalent structures being designated as a gap means. 
     The outer housing  12  and second wall means  13  comprises a top or ceiling  91 , end (side) walls  92 ,  93 , floor  94  back wall  95 , and front wall portions  34  common with portions  34  of first wall means  11  which interconnect the front perimeter portions of the inner and outer housings. A typical set of approximate dimensions for the present oven structure for an expanded oven from dual ovens where the partition means has been hinged back against the rear section  49  are as follows: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 (a) oven structure outside width 
                 36.0″ 
               
               
                   
                 (b) oven structure outside depth 
                 17.2″ 
               
               
                   
                 (c) oven structure outside height 
                 12.0″ 
               
               
                   
                 (d) oven structure interior width 
                 30.0″ 
               
               
                   
                 (e) oven structure interior depth 
                 14.0″ 
               
               
                   
                 (f) oven structure interior height 
                 9.0″ 
               
               
                   
                   
               
             
          
         
       
     
     The center partition means  79  hinges back against the rear wall section  49  to create an enlarged cooking chamber approximately 30 in. wide, 14 in. deep and 9 in. high. Heat insulation material  42  such as glass wool is positioned between said housings in conventional manner. 
     A first electrical resistance heating means such as elements  46  for plate means  44  is positioned under the plate within lower heating cavity  16 . A second electrical resistance heating means such as elements  48  is positioned under ceiling  14  within upper heating cavity  45 . Heat radiation shielding means generally designated  50  is positioned between heating means  48  and upper section  43  of said third wall means. This shielding means  50  in a preferred structure comprises base or support ledges  51  formed from grooves  52  in the side walls  22 , 24 , and a slide plate  53  having inner and outer ends  105  and  106  respectively, with push-pull tab  104 , and formed to provide air flow slots  54  therethrough bordered by shielding lands  55  and having slot ends  107 . Plate  53  is slidably supported on the ledges  51  and is operator slidable with respect to heating coils or the like elements  48  between a heat radiation blocking position  56  ( FIG. 3 ) and a heat radiation non-blocking position  58  ( FIG. 3 ) with respect to cooking chamber  40 . Operator access to tabs  104  is provided by, e.g., a small hinged  108  door  109 , preferably spring urged to closed position, such as  108  mounted on front wall portion  34  of each oven. 
     An air flow circulating fan  60  communicating with the cooking chamber  40  and the upper heating cavity  45  is adapted to cycle (circulate) air from the cooking chamber thru outlet  19 ,  19 A or  19 B into the air feed channel  39 , into upper heating cavity  45 , over the heating elements  48 , down thru slots  54  into the cooking chamber  40  and across plate means  44  and then back thru said outlet to complete the circulation cycle. 
     The housings  10  and  12  are of conventional construction such as, e.g., 14-26 gauge sheet steel which can be ceramic glazed or otherwise coated with high temperature resistant paint or the like material. In the drawings the structures appear as thick monolithic castings for purposes of clarity, however the sheet metal joints can be made by conventional techniques of welding, brazing, metal interlocking crimping, rivets, sheet metal screws or the like. 
     A steam injection system such as shown and described in U.S. Pat. No. 6,860,261 B2 is preferably used with the present invention and is shown in  FIG. 6  as a water inlet tube  96  extending between walls  11  and  13  and connected to a steam generating tube  97  containing stainless steel balls  98 . A conventional oven light  99  is set into the oven side wall. 
     As shown in  FIG. 2 , metal spacers  15  or an equivalent structure can be placed and fixed strategically to the inner and outer housings to maintain a rigid spacing and connection between the two housings and for providing dimensioned spaces for containing the insulation material  42 . Side walls  22  and  24  and center support  100  (part of first wall means  11 ) are shown as grooved as at  52  for supporting slide plate  53 , and these elements are further grooved at  25  for supporting heat sink plate means  44 , however other structures such as elongated metal or ceramic angle members such as  26  welded or riveted to first wall means  11  as shown in  FIG. 2A  may be employed. 
     Referring to  FIG. 4 , the ceramic plate rear support  20  comprises a lateral ledge such as  27  at the back of the cooking chamber and  28  at the front thereof. It is noted that the shallow ledge  28  allows the plate to be slid into grooves  25  if there is sufficient looseness in the fit of the plate therein such as to accommodate the small drop down  29 . This structure locks the plate horizontally in place. The ceramic plate preferably consists of Silica based comminuted material and has a thickness of from about 0.3 to about 1.5 in., most preferably from about 0.5 to about 0.75 in. 
     It is preferred to provide some type of gripping structure such as metal or ceramic tab  104  on the front of each slide plate  53  to allow the chef to easily slide the plates in or out with respect to heating elements  48 . 
     Each heating means  46  and  48  and thermocouple sensors therefor can be selected from any commercially available types including the finned or tubular heaters and thermocouples as described in the 1999-2005 Watlow Electric Manufacturing Company brochures from WATLOW, 5710 Kenoshat Street, Richmond, Ill. 10071. The doors and handles can be selected, for example, from those shown in the Jun. 23, 2005 brochures of Mills Products, Incorporated, 219 Ward Circle, Suite 2, Brentwood, Tenn. 37027. 
     The air circulating fan  60  most preferably is a cross flow or tangential blower type as described in the Jun. 23, 2005 brochure of EUCANIA International, Inc. Such fans give an even laminar air flow from back to front substantially completely across (side to side) of the present oven which greatly facilitates temperature control by the present invention throughout the oven cooking chamber. 
     An example of these fans for use in the present invention, referring to  FIGS. 3 ,  4 ,  4 A and  5 , comprises a plurality, e.g., 10-30 elongated blades  21  of about 18 in. length and about ⅜-¼ in. width as shown in  FIG. 5  and having a radiused curvature and fixed in a circle of about 1.6 in. OD at one end into a disc  31  having a shaft  32  which is rotatably mounted in a bearing housing  33 . The other end of the blades are fixed into a disc  35  having a shaft  36  which is rotatably mounted in a bearing housing  37 . Shaft  36  comprises, e.g., the output shaft of an electrical motor  57 . Bearing housing  33  and  37  are attached to and fixed in position relative to each other by wall means  11  such as portions  59  thereof into which shafts  32  and  36  are respectively mounted. It is noted that where the oven dimensions require long, e.g., 18 in. tangential fans, supporting discs preferably are used to support the blades and fix them in position relative to each other in the middle or other intermediate positions of their length. In order for the fan to have its maximum efficiency, the most preferred configuration for upper wall section  43  is shown in  FIG. 5  wherein the fan outlet side is adjacent a vortex tongue portion of  43  delineated “VTP”. 
     Referring to  FIG. 8  which is semi-exploded view for clarity, two tangential fans  62 , 64  are used for the two oven chambers  66  and  68  respectively. The drive motor  70  for fan  64  has a tubular drive shaft  72  fixed to the fan disc ends  72 ′ and rotatably mounted in bearings  74  fixed in first wall means  11 . The drive motor  76  for fan  62  has drive shaft  78  fixed to the fan disc ends  62 ′ and rotatably mounted thru the bore  80  of shaft  72 . 
     Referring to  FIGS. 9 and 10  the separate fans of separate ovens are clutch driven by clutches of  FIG. 9  or  FIG. 10  or any other conventional clutch faces. In this embodiment equivalent structures to those of  FIGS. 3 ,  4 ,  4 A and  5  are numbered the same. 
     In  FIG. 9 , the adjacent ends of the drive shafts are provided one with a friction clutch disc  82  and the other with, e.g., a smooth steel faced disc  84 . In this fan drive version, a thrust bearing  86  is provided to reduce endwise friction when the clutch is engaged. A compression spring  61  and thrust bearing  63  are provided to ensure release of the clutch when only on fan is to be operated. The clutch is actuated to drive both fans by means of a lever  69  pivotally mounted at  71  to a stationary portion of the oven and at  73  to thrust bearing  63 . Lever  69  may be connected to the armature  75  of a solenoid  77  incorporated, e.g., into the electronic control system for the oven. Alternatively, the lever may extend outwardly thru the oven front for manual operation. 
     Referring to  FIGS. 2 and 3 , a partition means generally designated  79  providing aforesaid side walls  24  is mounted on back wall  30  by hinges  81  of any convenient type such that it can be swung back against wall  30  by a user when it is desired to use a single larger cooking chamber. This partition means preferably is hollow core as shown containing heat insulation material  42 . Strips  83  of firm heat insulation adhesive material can be used along the top, bottom, front and rear of the partition to assist in isolation of the two chambers as desired. The strips can also be held in place by conventional mechanical means. 
     Referring to  FIG. 3A  the oven doors  38  most preferred comprise a frame  85  surrounding and fixed to an outer glass panel  87 , a middle glass panel  88 , and an inner glass panel  89 . The cavity  90  is vented to protect against excessive heat generated air pressure. A heat insulating—sealing strip such as  83  can be affixed to one or both doors where desired. Conventional hinge means and latching means for the door are employed. 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications will be effected with the spirit and scope of the invention.