Abstract:
Improved cooling is achieved in a cooking appliance including a burner box having at least one burner assembly disposed therein. A control box containing control electronics is spaced below the burner box so that a gap is created between the burner box and the control box. A plurality of fins is formed on at least one wall of the control box for cooling the control electronics by natural convection.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to cooking appliances such as cooktops and ranges and more particularly to cooling the control electronics in such appliances. 
     Modern cooking appliances increasingly incorporate electronic control systems for controlling operation of the appliance. These control electronics are ordinarily contained in a separate control box located in close proximity to the heating elements of the cooking appliance. In many cases, these control electronics need to be protected from the high temperatures generated by the cooking appliance. The control electronics are also typically cooled in some manner to protect them from the heat generated by the control electronics themselves, particularly the portion of the electronics involved in power control. 
     In many conventional cooking appliances, the control electronics are cooled by forced convection, typically a fan arranged to blow cooling air over the control electronics. However, the use of a fan is often undesirable because of the noise associated with a running fan. Furthermore, fans can add to the overall cost of the appliance and typically carry a relatively high service call rate. 
     Accordingly, it is desirable to provide a cooking appliance in which the control electronics are cooled by means other than forced convection. 
     BRIEF SUMMARY OF THE INVENTION 
     The above-mentioned need is met by the present invention, which provides a cooking appliance including a burner box having at least one burner assembly disposed therein and a control box containing control electronics. The control box is spaced below the burner box so that a gap is created between the burner box and the control box, and a plurality of fins is formed on at least one wall of the control box for cooling the control electronics by natural convection. 
     The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the concluding part of the specification. The invention, however, may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
     FIG. 1 is a perspective view of a cooking appliance having a burner box and a control box. 
     FIG. 2 is a side view of the cooking appliance of FIG.  1 . 
     FIG. 3 is a perspective view of one wall of the control box of FIG.  1 . 
     FIG. 4 is another perspective view of the control box wall shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views, FIG. 1 shows a cooking appliance  10  having a housing or burner box  12  and a glass-ceramic plate  14  disposed on top of the burner box  12  to provide a cooking surface. Located directly underneath the plate  14  is a number (typically, but not necessarily, four) of burner assemblies (not shown). Circular patterns  16  formed on the cooking surface of the plate  14  identify the position of each burner assembly. A control box  18  is located below the burner box  12 . The control box  18  contains control electronics (not shown), which are generally known in the art and control the operation of the appliance  10 . A control panel  20  is provided on the plate  14 . As is known in the field, the control panel  20  includes touch pads, knobs or the like that allow a user of the appliance  10  to interface with the control electronics and individually control the temperature of the burner assemblies. 
     The control electronics can be any type known in the art. Cooking appliances generally include a power source (typically a standard 240 volt, 60 Hz AC power source) that is coupled to the heating elements of the burner assemblies for supplying power thereto. A power source control means such as a triac is provided for each burner assembly to regulate the level of power delivered to the corresponding heating element. A triac is a conventional semiconductor device capable of conducting current in either direction across its main terminals when triggered by either a positive or negative voltage applied to its gate terminal. An electronic controller supplies the gate signal. The controller controls the power applied to the heating element by controlling the rate at which gate signals are applied to the triac gate terminal. The gate signal pulse rate is dictated by the power setting selections for the burner assembly entered by user actuation of the control panel  20 . 
     The cooking appliance  10  shown in FIG. 1 is the type of cooking appliance, commonly referred to as a cooktop, that is designed to be mounted into a countertop. However, it should be noted that the present invention is not limited to cooktops, but is also applicable to other types of cooking appliances such as ranges. Furthermore, the present invention is not limited to glass-ceramic cooking appliances, as it is equally applicable to cooking appliances without glass-ceramic surfaces. 
     Referring now to FIG. 2, it is seen that the control box  18  is spaced below the burner box  12  such that an air gap  22  is created between the bottom of the burner box  12  and the top of the control box  18 . The air gap  22  acts as a thermal barrier between the burner box  12  and the control box  18  that impedes heat transfer from the burner box  12  to the control box  18 , and thus to the control electronics. Optionally, a layer of thermal insulation could be placed in the air gap  22  to further resist heat transfer. The control electronics in the control box  18  are electrically connected to the appropriate components in the burner box  12  by suitable wiring, represented collectively in FIG. 2 by a cable  24 . 
     The control box  18  includes a plurality of exterior fins  26  for dissipating heat generated by the control electronics themselves. In one embodiment, the fins  26  are formed on one of the six walls of the control box  18 , which wall is referred to herein as the heat sink wall and identified by reference numeral  28 . As best seen in FIGS. 3 and 4, the heat sink wall  28  has an interior side  30  and an exterior side  32 , on which the fins  26  are formed. The heat sink wall  28  is a relatively thick piece made of a material, such as aluminum, that has a high thermal conductivity. Thus, the heat sink wall  28  has a large capacity to absorb heat from the control electronics in the control box  18 . In one preferred embodiment, the heat sink wall  28  is thicker than the other walls of the control box  18 . For example, the heat sink wall  28  can have a thickness on the order of about 0.25-0.50 inches (0.635-1.27 cm). 
     The fins  26  formed on the exterior side  32  of the heat sink wall  28  promote dissipation of the absorbed heat to the ambient by natural convection. The fins  26  can be integrally formed on the heat sink wall  28 ; that is, the fins  26  and the heat sink wall  28  comprise a single piece of material having a high thermal conductivity. The open space above the control box  18  due to the air gap  22  provides sufficient room for air to circulate through the fins  26 . Furthermore, the control box  18  is located with respect to the burner box  12  such that the fins  26  extend laterally beyond the side of the burner box  12 , as seen best in FIG.  2 . The fins  26  are preferably, but not necessarily, arranged vertically to further promote air circulation. 
     To enhance heat transfer from the control electronics to the heat sink wall  28 , the control electronics can be directly mounted to the interior side  30 . For example, FIG. 3 shows a plurality triacs  34  (i.e., the power control electronics) mounted to the interior side  30  of the heat sink wall  28 . Thus, heat generated by the triacs  34  during operation will be transferred to the heat sink wall  28  by conduction. 
     The foregoing has described a cooking appliance in which the control electronics are disposed in a finned control box that is spaced below the appliance&#39;s burner box. Thus, the control electronics are located away from the heat generated by the cooking appliance, and the heat generated by the control electronics themselves is dissipated using natural convection. This avoids the cost and noise associated with forced convection cooling. 
     While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention as defined in the appended claims.