Abstract:
Improved cooling is achieved in a cooking appliance having a burner box including an air inlet and at least one burner assembly disposed therein. A control box containing control electronics is located adjacent to the burner box. The control box is provided with an air inlet and an air outlet for permitting a flow of cooling air therethrough. Also provided is a fan for causing cooling air to pass through the control box. The burner box air inlet is positioned so that cooling air exiting the control box via the control box outlet enters the burner box via the burner box inlet. In one preferred embodiment, an inner box is disposed in the burner box so as to define a compartment into which the cooling air flows.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to cooking appliances such as cooktops and ranges and more particularly to cooling various electronic components 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 heated elements of the cooking appliance. Because the control electronics cannot survive the elevated temperatures generated by the cooking appliance, cooling air is blown through the control box for cooling the electronics therein. The spent cooling air is discharged outside of the appliance. To enhance the functionality of the electronic control system, various sensors and other electronics are also being utilized. These additional components are often placed in close proximity to the heated elements of the cooking appliance. 
     Extensive use of electronics is particularly common in cooking appliances having a glass-ceramic plate as the cooking surface. The glass-ceramic plate presents a pleasing appearance and is easily cleaned in that its smooth, continuous surface lacks seams or recesses in which debris can accumulate. The glass-ceramic plate also prevents spillovers from falling onto the heating elements below. Such cooking appliances typically include a number of heating units mounted under a smooth glass-ceramic plate. A utensil placed on the glass-ceramic plate is directly heated by energy radiated from the appropriate heating unit. Alternatively, the glass-ceramic plate is sufficiently heated by the heating unit so that the utensil is heated by conduction from the heated glass-ceramic plate. 
     In either case, provision should be made to avoid overheating the glass-ceramic plate. For most glass-ceramic materials, the operating temperature should not exceed 600-700° C. for any prolonged period. Under normal operating conditions, the temperature of the glass-ceramic plate will generally remain below this limit. However, conditions can occur that can cause this temperature limit to be exceeded. Commonly occurring examples include operating the appliance with a small load or no load (i.e., no utensil) on the cooking surface, using badly warped utensils that make uneven contact with the cooking surface, and operating the appliance with a shiny and/or empty utensil. 
     To protect the glass-ceramic plate from extreme temperatures, glass-ceramic cooktop appliances ordinarily have some sort of temperature sensor for monitoring the temperature of the glass-ceramic plate. If the glass-ceramic plate approaches its maximum temperature, the power supplied to the heating unit is reduced to prevent overheating. In addition to providing thermal protection, such temperature sensors can be used to provide temperature-based control of the cooking surface and to provide a hot surface indication, such as a warning light, after a burner has been turned off. 
     It is common to locate a temperature sensor beneath each heating unit. The temperature sensors are thus subject to the high temperatures generated in the appliance. Other types of sensors provided to enhance the functionality of the electronic control system are typically located in the hot regions of the appliance. Such sensors include sensors for detecting characteristics, such as the temperature, size or type, of a utensil placed on the cooking surface, sensors for detecting the presence or absence of a utensil, and sensors for detecting properties such as boiling state of the utensil contents. 
     These sensors are susceptible to failure because of the high temperatures they are exposed to. Accordingly, it is desirable to provide a cooking appliance in which temperature and other sensors are cooled to prolong their life. 
     BRIEF SUMMARY OF THE INVENTION 
     The above-mentioned need is met by the present invention, which provides a cooking appliance comprising a burner box having an air inlet and at least one burner assembly disposed therein. A control box containing control electronics is located adjacent to the burner box. The control box is provided with an air inlet and an air outlet for permitting a flow of cooling air therethrough. Also provided are means for causing cooling air to pass through the control box. The burner box air inlet is positioned so that cooling air exiting the control box via the control box outlet enters the burner box via the burner box inlet. In one preferred embodiment, an inner box is disposed in the burner box so as to define a compartment into which the cooling air flows. 
     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. 
     FIG. 2 is an exploded perspective view of the cooking appliance of FIG. 1 with the cooking surface removed. 
     FIG. 3 is a sectional view taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a sectional view taken along line  4 — 4  of FIG.  3 . 
     FIG. 5 is top sectional view of a second embodiment of a cooking appliance. 
     FIG. 6 is a sectional view taken along line  6 — 6  of FIG.  5 . 
     FIG. 7 is a schematic view of a third embodiment of a cooking appliance. 
    
    
     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 in FIG.  1 ). 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 adjacent to the burner box  12  and under the plate  14 . As is known in the art, the control box  18  contains control electronics (not shown) that 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 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 FIGS. 2-4, it is seen that the burner box  12  has a generally rectangular configuration except for a recess  22  set in one corner thereof into which the control box  18  fits. Thus, the burner box  12  comprises a primary section  24  and a smaller secondary section  26 . The secondary section  26  extends laterally from the primary section  24  and has a smaller front-to-back dimension than the primary section  24  so as to define the recess  22 . It should be noted that this recessed configuration is just one possible embodiment of the burner box  12  and that other configurations could be used as alternatives. 
     A plurality of burner assemblies  30  is disposed within the primary section  24  of the burner box  12 , directly underneath the plate  14  (which is not shown in FIG. 2 for illustration purposes). Each burner assembly  30  includes a controllable energy source such as an open coil electrical resistance element  32 . The heating element  32  is secured to a burner casing  34  that is supported under the glass-ceramic plate  14  in a conventional manner. A temperature sensor  36  is provided to sense the temperature of the glass-ceramic plate  14 . The temperature sensor  36  is an optical device, such as an infrared thermometer or the like, although other types of temperature sensors could be used. The optical temperature sensor  36  is mounted in the burner casing  34 , at the center of the coiled heating element  32 , and is oriented so as to receive radiation from the portion of the glass-ceramic plate  14  directly above the burner assembly  30 . In response to this radiation, the optical temperature sensor  36  generates a signal that corresponds to the temperature of the glass-ceramic plate  14 . The temperature signal is supplied to the control electronics and used in the control of the cooking appliance  10 . The body of the temperature sensor  36 , which may be a cylinder of a high thermally conductive material that can function as a heat sink, extends downward from the burner assembly  30 . 
     The secondary section  26  of the burner box  12  can contain other components that contribute to the control of the appliance  10 . For example, an accelerometer  38  can be mounted in the secondary section  26 . 
     The accelerometer  38 , which measures vibrations, is able to provide an indication of when the contents of a utensil on the appliance  10  are boiling. User interface electronics  40  can also be located in the secondary section  26 . Various other components could also be housed in the secondary section  26 . 
     An inner box  42  having approximately the same width and length dimensions as the inner box primary section  24  is disposed in the upper portion of the primary section  24 . As best seen in FIG. 3, the inner box  42  has a smaller depth than the burner box  12  so that a compartment  44  is defined between the base of the inner box  42  and the base of the burner box  12  in the primary section  24 . The inner box  42  encloses the burner assemblies  30  so as to separate them from the compartment  44 . However, the bodies of the temperature sensors  36  extend through the base of the inner box  42  into the compartment  44 . The compartment  44  is in fluid communication with the interior of the secondary section  26 . 
     The control box  18  has an air inlet  46  formed in one side thereof and an air outlet  48  formed in an opposite side. A fan  50  is located at the air inlet  46  for blowing ambient cooling air into the control box  18  via the air inlet  46 . The cooling air passes through the control box  18 , thereby cooling the control electronics therein, and exits the control box  18  via the air outlet  48 . 
     The temperature of the cooling air exiting the air outlet  48  will be elevated above ambient temperature because it has removed heat from the control electronics. However, this air still has cooling capacity. Thus, instead of simply discarding this air by discharging it back to the ambient, it is used to cool components in the burner box  12 . Specifically, an air inlet  52  is formed in the wall of the burner box  12  that forms the recess  22  and is adjacent to the control box air outlet  48 . The burner box air inlet  52  is positioned in the wall so as to provide ingress to the compartment  44 . A connector duct  54  extending between the control box air outlet  48  and the burner box air inlet  52  directs the air exiting the outlet  48  into the compartment  44 . This air circulates in the compartment  44  and also flows into the secondary section  26 . 
     As mentioned above, a portion of each temperature sensor  36  extends into the compartment  44 . Thus, the temperature sensors  36  are cooled by the air circulating in the compartment  44 . Similarly, the accelerometer  38  and the user interface electronics  40  are cooled by the air passing into the secondary section  26 . Exhaust vents  56  are formed at various locations in the burner box  12  to exhaust the cooling air. Exhaust vents  56  are positioned about the primary section  24  such that cooling air will flow past each of the temperature sensors  36 . Another exhaust vent  56  is formed in the secondary section  26 , on the wall opposite the primary section  24 , to insure a flow of cooling air through the secondary section  26  and past the accelerometer  38  and interface electronics  40 . 
     It should be noted that the fan  50  can alternatively be located in the connector duct  54  between the control box  18  and the burner box  12 , instead of at the control box air inlet  46 . Thus, cooling air will be drawn into the control box  18  and across the control electronics and then blown into the compartment  44 . 
     Turning now to FIGS. 5 and 6, an alternative embodiment is shown. In this case, a duct  58  is placed in the burner box  12 , under the inner box  42 , for directing cooling air therethrough instead of allowing the air to freely circulate through the compartment  44  and the secondary section  26 . The duct  58  is a three-sided structure that combines with the base of the burner box  12  to define an enclosed passageway. This passageway extends through the burner box  12  in a substantially U-shaped path that passes under each of the burner assemblies  30 . The duct  58  thus directs cooling air past each of the temperature sensors  36 , which extend through the top of the duct  58  into the passageway. The duct  58  also extends past the accelerometer  38  and the interface electronics  40  in the second section  26 . A first end of the duct  58  is in aligned with the burner box air inlet  52 , and the second end of the duct  58  is aligned with an exhaust vent  56  formed in the wall of the secondary section  26  that is opposite the primary section  24 . Thus, cooling air exiting the control box  18  enters the duct  58  through the burner box air inlet  52 , flows through the duct  58  and cools the temperature sensors  36 , accelerometer  38  and interface electronics  40 , and exits the duct  58  and the appliance  10  via the exhaust vent  56 . In this embodiment, only the one exhaust vent  56  is used. 
     As best seen in FIG. 6, the duct height is such that an air gap  60  is formed between the bottom of the inner box  42  and the top of the duct  58 . The air gap  60  provides some insulation between the duct  58  and the hot inner box  42 , thereby preserving the cooling capacity of the air in the duct  58 . 
     The present invention is not limited to cooking appliances in which the control box is located on the side of the burner box. FIG. 7 schematically shows another embodiment of a cooking appliance  10  in which the control box  18  is located below the burner box  12 . In this case, the burner box air inlet  52  is located in the base of the burner box  12 , aligned with the control box air outlet  48  formed in the top of the control box  18 . Thus, air exiting the control box  18  flows into the compartment  44  defined between the base of the inner box  42  and the base of the burner box  12  via the burner box air inlet  52 . Although FIG. 7 shows the air freely circulating in the compartment  44 , this embodiment could also use a duct  58  for directing the cooling air through the compartment. 
     The foregoing has described a cooking appliance in which air used to cool the control electronics is used to cool other components in the burner box. 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.