Abstract:
A combined rotisserie and convection oven includes a cooking chamber having a first end and a second end. A fan is in fluid communication with the cooking chamber for creating an airflow in the cooking chamber, and a removable spit is rotatably suspended between the first and second ends of the cooking chamber. A heating element for providing the cooking temperature is provided in the cooking chamber, and is movable to a plurality of positions within the cooking chamber.

Description:
[0001]    The present invention generally relates to ovens, and more particularly to an oven that functions both as a rotisserie oven and a convection oven.  
         BACKGROUND  
         [0002]    Ovens that have both rotisserie and convection cooking features are known. These ovens typically include a rotating spit and a heating element for rotisserie cooking, and a fan for circulating hot air within the oven to facilitate convection cooking, in conjunction with or independently of rotisserie cooking. The ovens may have a dedicated heating element for rotisserie cooking and a separate heating element for convection cooking, or they may employ the same heating element for both rotisserie and convection cooking. Typically, though, the known ovens generally have a rectangular shaped cooking chamber and a fan located either on the top or the back of the cooking chamber. These arrangements generally do not allow airflow to closely travel around or surround the food item, and also creates “dead zones,” particularly in the corners where airflow is restricted, resulting in temperature and airflow variations in the cooking chamber. Thus, desired uniform cooking is difficult to attain in these ovens.  
           [0003]    Another feature that is common to known ovens is a stationary heating element. Typically, the heating element(s) is located in the cooking chamber at a location generally above the food. While this arrangement may be useful in the type of cooking where direct radiant heat source is required, as in broiling or roasting, for example, it is not ideal for baking, in which direct radiant heat is generally not desirable.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed to a combined rotisserie and convection oven which includes a cooking chamber having a first end and a second end. A fan is in fluid communication with the cooking chamber for creating an airflow in the cooking chamber, and a removable spit is rotatably suspended between the first and second ends of the cooking chamber. A heating element for providing the cooking temperature is provided in the cooking chamber, and is movable to a plurality of positions within the cooking chamber. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a perspective view of an oven in accordance with one embodiment of the invention;  
         [0006]    [0006]FIG. 2 is an exploded perspective view of the oven of FIG. 1;  
         [0007]    [0007]FIG. 3 is a sectional view of the oven of FIG. 1, generally along line  3 - 3 ;  
         [0008]    [0008]FIG. 4 is a partial sectional view of the oven of FIG. 1, generally along line  4 - 4 ;  
         [0009]    [0009]FIG. 5 shows a device for rotating a heating element in accordance with one embodiment of the present invention;  
         [0010]    [0010]FIG. 6 shows the rotating device of FIG. 5 connected to a motor for driving the rotating device in accordance with one embodiment of the invention;  
         [0011]    [0011]FIG. 7 is a side view of the oven of FIG. 1;  
         [0012]    [0012]FIG. 8 shows another embodiment of a device for rotating the heating element in accordance with another embodiment of the present invention;  
         [0013]    [0013]FIG. 9 shows another embodiment of a control panel for operating the oven of the invention; and  
         [0014]    [0014]FIG. 10 is a diagram illustrating a cyclonical airflow created in the cooking chamber of the oven of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    Turning now to FIGS.  1 - 2 , the oven in accordance with one embodiment of the invention is designated generally at  10 , and includes, a cooking chamber  12  provided between a pair of end housings  14 ,  16 . A leg  18  attached to the bottom of the end housings  14  and a leg  20  attached to the bottom of the end housing  16  support the oven  10  off the surface on which the oven is placed. A door  22  is hinged to the end housing  14  and allows access to the cooking chamber  12  when opened by a handle  24  on the opposite side of the door proximate the end housing  16 . The door  22  includes preferably a clear heat-resistant glass panel  26  to enable the user to view into the cooking chamber  12 .  
         [0016]    Handles  28 ,  30  are formed in the end housings  14 ,  16 , respectively, to allow the user to grasp and lift the oven  10 . The handles  28 ,  30  are spaced respectively from side walls  32 ,  34  of the cooking chamber  12  (best shown in FIG. 2), to insulate the handles from the cooking chamber. On the end housing  16  (shown on the right in FIG. 1), a control panel  35  is provided and includes a timer switch  36  for setting the desired cooking time, and a temperature switch  38  for setting the desired temperature in the cooking chamber  12 . A removable liner pan  40  rest on a bottom  42  of the cooking chamber  12  (best shown in FIGS. 2 and 3) for catching any liquid or particles that may come off the food (not shown) being cooked.  
         [0017]    Turning now to FIG. 3, the heat source for the oven  10  is provided by a heating element  44 , which is preferably a ceramic coated infrared heater. The heating element  44  generally resembles a letter “m” on its side and extends substantially the width of the cooking chamber  12 . A reflection board  46  may be provided between the heating element  44  and a cylindrical wall  48  of the cooking chamber  12  to reflect heat towards the center of the cooking chamber.  
         [0018]    A plurality of elongated metal brackets  50  (two shown) are provided on the side wall  32  at various heights, and corresponding brackets  52  are provided at the same height on the opposite side wall  34 . The brackets  50 ,  52  extend generally horizontally along the side walls  32 ,  34 , but not completely to the cylindrical wall  48  (best shown in FIG. 4). The corresponding pairs of brackets  50 ,  52  are configured to have a generally planar cooking rack  54  placed thereon for holding food. The rack  54  may be a pan or a grill, and may be placed on any one of the pairs of brackets  50 ,  52  as desired by the user.  
         [0019]    In accordance with an embodiment of the present invention, the end housing  16  includes a spit rotating motor  56  which is attached generally centrally to the side wall  34 . The spit  58  extends between the side walls  32 ,  34 , and rests rotatably and removably at one end on a support  60  (best shown in FIG. 4), which is located generally at the center of the side wall  32 , and rotatably engages the motor  56  through the side wall  34  at the other end. The motor  56  is a gear reduced type including a gear transmission box (not separately shown) to reduce the rpm to the rotating spit  58 . The final speed of roation will be around 2-3 rpm. A light source  61  is also provided in the end housing  16  and illuminates the cooking chamber  12  through an opening  62  in the side wall  34 . A glass cover  63  is installed in the opening  62 , and separates the light source  61  from the cooking chamber  12 . The light source is an incandescent light bulb and is connected to an on-off switch (not shown).  
         [0020]    A blower fan  64  is also provided in the end housing  16 , and is exposed to the cooking chamber  12  through an opening or recess  65 . The blower fan  64  is made of aluminum or other heat resistant material to provide convection hot airflow inside the cooking chamber  12 . The fan  64  is attached to a C-frame motor  66 , which is activated to rotate the fan  64 . A fan case  67  separates the blower fan  64  from the other areas of the end housing  16 , to prevent hot air from getting into the end housing. In front of the fan  64 , there are multiple openings or a protection grill  68  to prevent food particles from entering the fan case  67 . A cooling fan  69  is operatively connected to the drive shaft of the motor  66  on the opposite end from the blower fan  64  for cooling the inside of the end housing  16 . When energized, air (shown as curved arrows) is pulled in from the outside of the oven  10 , through a plurality of air inlets  70  formed on the end housing  16  (best shown in FIG. 2), and circulated within the end housing to cool the end housing.  
         [0021]    In the other end housing  14 , a heating element rotating motor  71  is attached to the side wall  32  proximate the leg  18 . The motor  71  rotatably drives a shaft  72  connected to a drive gear  74 , which extends into the cooking chamber  12  through the side wall  32 . The drive gear  74  is adapted and configured to engage a generally “D” shaped wheel  76  (best shown in FIG. 5) for positioning the heating element  44  at various locations within the cooking chamber  12 . A selector switch  78  (also shown in FIG. 7) controlled by the user sets the positions of the heating element  44  via the motor  71 . Preferably, the motor  71  is a gear reduced type including a gear transmission box (not separately shown) to reduce the rpm to the drive gear  74 . The selector switch  78  is operatively connected to a control box  79 , which controls the motor  71  for moving the heating element  44  to the desired position corresponding to the selector switch positions. The selector switch  78  also controls the spit rotating motor  56  via the control box  79 , so that the spit  54  is rotated to coincide with a predetermined position of the heating element  44 . For example, the spit rotating motor  56  is energized to rotate the spit  58  when the selector switch  78  is rotated to a position to move the heating element  44  to facilitate rotisserie cooking. The motor  56  is not energized when the switch  78  is rotated to move the heating element  44  to facilitate the type of cooking which does not require direct radiant heat such as baking.  
         [0022]    Turning now to FIGS.  4 - 7 , the heating element  44  is adapted to be located at a top position A (shown in phantom) and rotated around to a position B underneath the rack  54  along the path indicated by arrows C. In this manner, the heating element  44  can be positioned at the locations best suited for the type of cooking desired by the user. The rotation of the heating element  44  is made possible through the D-shaped wheel  76  (best shown in FIG. 5). As shown in FIGS. 5 and 6, the heating element  44  is attached to and extends perpendicularly out of the flat surface  75  of the wheel  76  at approximately the midpoint in the curved portion of the wheel. The wheel  76  is rotatably attached to the side wall  32  at point D on the straight portion of the wheel and at approximately the center of the side wall. The wheel  76  includes teeth  80  which are configured to engage teeth  82  that are formed on the drive gear  74  connected to the heating element rotating motor  70 . As the drive gear  74  is driven by the motor  71 , the wheel  76  rotates about point D.  
         [0023]    Turning now to FIG. 8, and in accordance with another embodiment of the invention, a D-shaped wheel  76 ′ for rotating the heating element  44  is connected directly to the selector switch  78 . In this arrangement, the wheel  76  is rotated manually by the user by turning the switch  78 . As such, the motor  71  and the gear  74  are unnecessary, and accordingly, the teeth  80  formed on the wheel  76  (best shown in FIG. 5) are also not required. The selector switch  78  is electrically connected to the spit rotating motor  56  to energize the motor when the heating element  44  is rotated to a position that facilitates rotisserie cooking (Position A in FIG. 4).  
         [0024]    In operation, food (not shown) is placed on the cooking rack  54 , and the heating element  44  is located at position B (best shown in FIG. 4) for cooking food on the top of the rack  54 . In this manner, the oven  10  functions as a convection oven. To operate the oven  10  as a rotisserie oven, food is skewered through the spit  58  (best shown in FIG. 3) and the heating element  44  is located at position A (best shown in FIG. 4), so that direct radiant heat is applied to the food.  
         [0025]    Regardless of the type of cooking, the desired cooking temperature is set using the temperature switch  38 , and the cooking time is set by the timer switch  36  (best shown in FIG. 1). The timer switch  36  activates the motor  66  for driving the fan  64  for creating the convection airflow in the cooking chamber  12 , and the fan  69  for generating cooling air in the end housing  16 . The timer switch  36  also energizes the heating element  44  to bring the temperature inside the cooking chamber  12  to the level set by the temperature switch  38 . The spit rotating motor  56  is activated coincident with the position of the selector switch  78  that facilitates rotisserie cooking, i.e., when the heating element  44  is set to position A (best shown in FIG. 4).  
         [0026]    Turing now to FIG. 9, and in accordance with another embodiment of the invention, a digital key pad  84  is provided on the control panel  35  for operating the oven  10 . The key pad  84  is used to enter at least the the cooking temperature, the time and a start/stop signal. Data entered through the key pad  84  is process by a micro-processor or controller (not shown) provided behind the key pad  84 . A display panel  86  shows the data entered through the key pad  84  and the remaining cooking time, for example.  
         [0027]    The key pad  84  also includes a “Frozen Food” key, which when activated, automatically sets the temperature in the cooking chamber  12  to a predetermined temperature for a percentage of the set cooking time to defrost the food. The predetermined temperature is typically lower than the set cooking temperature, so that the surface of the food does not get burned. In operation, when the “Frozen Food” key is depressed, the temperature is automatically set to, for example, approximately 180° C. for 50% of the cooking time entered by the user. In this manner, the time involved in cooking frozen food is reduced, and the occurrence of food contamination during a defrost process is prevented.  
         [0028]    Turning now to FIG. 10, and in accordance with another embodiment of the invention, the cooking chamber  12  is generally cylindrically shaped and the fan  64  for generating airflow inside the cooling chamber  12  is provided at the side wall  34  at the end housing  16 . This arrangement causes the airflow to originate from the side of the cylindrical cooking chamber  12 , thereby eliminating dead zones and creating a cyclonical airflow (as shown by arrows) in the cooking chamber. As a result, a more consistent temperature is generated and flows around the food, resulting in a more uniformly cooked food.  
         [0029]    From the foregoing description, it should be understood that an improved oven has been shown and described which has many desirable attributes and advantages. The oven includes a movable heating element, and a cylindrical cooking chamber with a fan provided at the end of the chamber, which creates a cyclonical airflow for generating a uniform cooking temperature.  
         [0030]    While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims.  
         [0031]    Various features of the invention are set forth in the appended claims.