Abstract:
An airflow system of a cooking appliance having an oven cavity includes an intake portion, an exhaust portion and a diverter portion. The intake portion introduces an airflow into the cooking appliance that diverges into first and second airstreams. The first airstream enters the oven cavity and picks up moisture from food items being cooked, while the second airstream circulates outside the oven cavity. The diverter member guides the second airstream to mix with the first airstream at a predetermined region outside the oven cavity to transport the moisture through the exhaust portion and away from the cooking appliance. Preferably, the diverter member extends fore-to-aft below the oven cavity and includes a plurality of openings.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/554,367 filed Mar. 19, 2004. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention pertains to the art of cooking appliances and, more particularly, to an airflow system designed to eliminate potential moisture condensation associated with operation of a microwave cooking appliance. 
   2. Discussion of the Prior Art 
   During a typical cooking operation, a food item is placed into an oven cavity to be subjected to cooking temperatures. The cooking temperatures cause moisture contained in food items to be released into the oven cavity. This is particularly true in the case of microwave cooking. A microwave cooking operation is performed by directing microwave energy fields into an oven cavity, with the energy fields reflecting about and impinging upon a food item. As the microwave energy fields impinge upon the food item, the energy fields are converted into heat through two mechanisms. The first or ionic mechanism is caused by the linear acceleration of ions, generally in the form of salts present within the food item. The second is the molecular excitation of polar molecules, primarily water, present within the food item. 
   The excitation of polar molecules causes the water or moisture to be released into the oven cavity. The moisture can either condense within the oven cavity or be carried by air currents circulating in the oven cavity to a point outside the oven cavity. If the air currents are not sufficient enough to carry the moisture from the appliance, the moisture exiting from the oven cavity could condense on ducting or other structure employed to guide the air currents from the appliance. Moisture building up within the ducting or other structure will ultimately find a path that leads from the appliance. Obviously, developed moisture could cause damage to surrounding cabinetry or to control components of the overall appliance. This is particularly true in connection with a double wall oven incorporating control components directly below an oven cavity. 
   Several attempts to address this problem are found in the prior art. In one example, contained in U.S. Pat. No. 5,945,023, a number of holes are formed in a lower portion of a side wall of an oven cavity. The holes allow moisture to escape from the oven cavity and be directed through a bottom portion of the appliance. In another example proposed in U.S. Pat. No. 4,123,643, a first air current is directed past a magnetron before being introduced into the oven cavity to mix with a second air current. The combined air currents absorb moisture and are then directed out of a front portion of the oven cavity. 
   Despite the existence of the prior art arrangements, there still exists a need for an airflow system that will carry moisture away from a microwave cooking appliance in a manner that will assure that surrounding structure will not be negatively affected by the moisture. Specifically, there exists a need for an airflow system that will transport moisture laden air outside the oven cavity so that the moisture does not build-up, condense and drip on surrounding cabinetry or other appliance structure. 
   SUMMARY OF THE INVENTION 
   The present invention is directed an airflow system for a microwave cooking appliance. The cooking appliance includes a frame that supports an oven cavity. The airflow system is designed to direct an airflow both into and about the oven cavity. Toward that end, the airflow system includes an intake portion for introducing an ambient airflow into the cooking appliance. After entering through the intake portion, the ambient airflow diverges into a first airstream that is directed into the oven cavity and a second airstream that is directed at least beneath the oven cavity. The first airstream picks up moisture that is released by one or more food items during a cooking operation. The first airstream then exits the oven cavity to define an exhaust airstream that is directed to a lower portion of the cooking appliance. 
   The second airstream is directed beneath the oven cavity in order to cool components of the cooking system, such as a turntable motor. In accordance with the invention, a diverter is employed to assure that the second airstream is directed to merge with the first airstream at a predetermined region outside the oven cavity. With this arrangement, the second airstream mixes with the first airstream to carry the moisture away from the predetermined location and out of the appliance. 
   In accordance with the most preferred form of the invention, the diverter is positioned below the oven cavity and extends generally fore-to-aft across the frame. More specifically, the diverter includes a first end, positioned at a front section of the frame, that extends, through an intermediate portion, to a second end positioned at a rear section of the frame. The first end of the diverter is provided with a passage zone that allows the second airstream to enter and mix with the first airstream at the predetermined region. The passage is preferably formed by one or more openings, with or without louvers, that guide the second airstream toward the predetermined region beneath the oven cavity. With this arrangement, the second airstream combines with the first airstream to carry moisture, picked-up by the first airstream from the oven cavity, to exhaust outlets and away from the cooking appliance. Therefore, the moisture will not be able to condense into water droplets that can cause damage to surrounding cabinetry or other cooking appliance structure. 
   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 partial perspective view of a dual oven cooking appliance having an upper microwave oven constructed in accordance with the present invention and a lower radiant-type oven; 
       FIG. 2  is a partial perspective view of the cooking appliance of  FIG. 1 , with a door for the upper microwave oven shown in an open position; 
       FIG. 3  is a bottom plan view of the upper microwave oven of  FIGS. 1 and 2 , with a lower panel removed; 
       FIG. 4  is an enlarged, partial view of an underside of the upper microwave oven of  FIG. 1 , illustrating an airflow diverter plate including a plurality of round openings constructed in accordance with a first embodiment of the present invention; 
       FIG. 5  is an enlarged, partial view of an underside of the upper microwave oven of  FIG. 1  illustrating an airflow diverter plate including a plurality of louvered openings constructed in accordance with a second embodiment of the present invention; and 
       FIG. 6  is a partial cross-sectional view of the louvers of FIG.  5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With initial reference to  FIG. 1 , a cooking appliance constructed in accordance with the present invention is generally indicated at  2 . As depicted, cooking appliance  2  constitutes a double wall oven. However, as will become more readily apparent below, the present invention is not limited to this model type and can be incorporated into other oven configurations. In any event, in the embodiment shown, cooking appliance  2  constitutes a double wall oven including an upper oven  4  having an upper oven cavity  6  and a lower oven  8  having a lower oven cavity  10 . Cooking appliance  2  includes a frontal frame, part of which is indicated at  12 , to which both upper and lower oven cavities  6  and  10  are connected. 
   A door  14  is provided to selectively access upper oven cavity  6 . As shown, door  14  includes an elongated handle  15  at an upper portion  16 . Door  14  is adapted to pivot at a lower portion  18  to enable selective access to within oven cavity  6 . Door  14  is provided with a transparent zone or window  22  for viewing the contents of oven cavity  6  while door  14  is closed. In accordance with the invention, upper oven  4  constitutes a microwave oven. To this end, window  22  preferably incorporates a microwave choke screen portion  23 . In a corresponding manner, a door  24 , including an elongated handle  25  and a transparent zone or window  26 , is provided to selectively access lower oven cavity  10 . In the preferred embodiment, lower oven  8  constitutes a radiant or conbination radiant/convection oven. 
   As further shown in  FIG. 1 , cooking appliance  2  includes an upper control panel  36  and a lower control panel  38 . Upper control panel  36  is provided with a plurality of control elements generally indicated at  40 , a numeric keypad  42  and a display  44 . In general, control elements  40 , keypad  42  and display  44  enable a user to establish desired cooking operations for upper oven  4 . In a similar manner, lower control panel  38  is provided with a plurality of control elements  46 , a numeric keypad  48  and a display  49  for establishing desired cooking operations within lower oven  8 . Since the particular manner in which upper and lower ovens  4  and  8  are programmed does not constitute part of the present invention, further details thereof will not be discussed herein. Finally, cooking appliance  2  is shown to include a plurality of exhaust outlets, one of which is labeled  52 , arranged between door  14  and lower control panel  38 . 
   As indicated above, upper oven  4  in accordance with the invention constitutes a microwave oven. With particular reference to  FIG. 2 , oven cavity  6  of upper or microwave oven  4  is defined by a bottom wall  59 , a rear wall  60 , opposing side walls  61  and  62 , and a top wall (not shown). Bottom wall  59  is constituted by a substantially flat, smooth surface to enhance cleanability of oven cavity  6 . However, oven cavity  6  is shown to include a rotatable platter or turntable  66  provided across a portion of bottom wall  59 , with turntable  66  being rotatably driven by a motor  69  arranged beneath upper oven cavity  6  (see FIG.  3 ). As also depicted in  FIG. 2 , upper oven  4  further defines at least one side panel  76  and a rear panel  78 . As indicated in  FIG. 2 , rear panel  78  is provided with a plurality of openings  80  that define an intake zone for introducing a stream of ambient air employed in connection with operation of upper oven  4 . As will be detailed more fully below, the air stream entering intake openings  80  diverges into a first air stream that is directed into upper oven cavity  6  through inlet openings  85  provided in side wall  61  and a second air stream that is directed beneath upper oven cavity  6 . 
   More specifically, with further reference to  FIG. 2 , the ambient air flow introduced through intake openings  80  is divided into a first air stream A that flows over certain power control components, such as a transformer  90  and then flows through a magnetron  95  into upper oven cavity  6  through inlet openings  85 , and a second air stream B. First air stream A then flows within upper oven cavity  6  and is led to outlet openings  100  provided in side wall  62  of upper oven cavity  6 . First air stream A is then directed between side wall  62  and a side panel  104  of cooking appliance  2  to a position beneath upper oven cavity  6 . 
   Due to the operation of upper oven  4 , first air stream A will pickup moisture within upper oven cavity  6  during a cooking operation. If left unchecked, the moisture in first air stream A could condense, particularly adjacent the lower front left corner of door  14 . As lower control panel  38  is located directly below door  14 , any condensation in this region could have an adverse effect on the associated electronics. In accordance with the present invention, this potential concern is addressed by assuring that the moisture-laden first air stream A is mixed with second air stream B prior to reaching exhaust outlets  52  as will be detailed fully below. 
   With particular reference to  FIGS. 3 and 4 , second air stream B is directed beneath upper oven cavity  6  and across motor  69  for turntable  66 . Instead of simply being able to freely flow out exhaust outlets  52 , second air stream B encounters a diverter  115 . In the most preferred form of the invention, diverter  115  includes a first end portion  117  positioned at a frontal section  120  of cooking appliance  2 , an intermediate portion  123  and a second end portion  125  positioned at a rear section (not labeled) of cooking appliance  2 . Diverter  115  is preferably constituted by a plate which is solid throughout intermediate portion  123  and second end portion  125 . However, first end portion  117  is provided with a plurality of openings  128  that define a passage zone. In accordance with the most preferred embodiment of the invention, first end portion  117  is actually angled relative to intermediate portion  123  and second end portion  125  as clearly shown in these figures. In any case, given that only first end portion  117  is provided with openings  128 , at least a portion of second air stream B is forced to exit from beneath upper oven cavity  6  at the lower front left corner, generally indicated  130 , of upper oven  4 . First air stream A exiting upper oven cavity  6  through outlet openings  100  must also flow through lower front left corner region  130 . Therefore, second air stream B will mix with first air stream A at predetermined region, i.e., the lower front left corner in the preferred embodiment disclosed, thereby forming mixed air stream C outside upper oven cavity  6 . The mixing of second air stream B with first air stream A in this manner assures that the moisture originally present in first air stream A will be directed through at least one of exhaust outlets  52  and away from cooking appliance  2 . 
   Based on the above, it should be readily apparent that the inclusion of diverter  115  controls the flow of second air stream B which, in turn, alters the flow of first air stream A. This arrangement has been found to eliminate any moisture build-up that could condense and drip onto lower control panel  38 . Of course, the exact positioning and structure of diverter  115  will depend upon the exhaust path for first air stream A and the positioning of exhaust outlets  52  for cooking appliance  2 . In accordance with the invention, openings  128  in diverter  115  can take various forms, including a plurality of circular holes  132  as shown in the embodiment of  FIG. 3 , and slotted openings  134  having associated louvers  136  as shown in the embodiment of  FIGS. 4 and 5 . In any case, openings  128  assure that first and second air streams A and B will mix at a predetermined region in order to prevent undesirable condensation of moisture leaving upper oven cavity  6  during cooking operations. 
   Although described with reference to preferred embodiments 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, although the mixing of the first and second air streams have been disclosed to particularly prevent condensation from forming on the lower control panel, the invention is applicable in other types of cooking appliances and can be used to protect cabinetry or other structure adjacent the appliance. In general, the invention is only intended to be limited by the scope of the following claims.