Abstract:
A control system for a cooking appliance enables a consumer to perform a complete cooking operation regardless of whether food is placed into an oven after a preheating operation or from a cold start. In general, under circumstances wherein the consumer does not intend to allow the oven to be properly preheated prior to inserting the food to be cooked therein, an initial programming operation is followed by an additional control sequence by the user to establish a cold start cooking operation wherein the lack of preheating is automatically compensated for, preferably by causing the oven to reach a peak temperature for the oven which is well above a temperature set by the user for the overall cooking operation. After the peak temperature is reached, the oven temperature is allowed to gradually reduce to the preprogrammed cooking temperature.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention pertains to the art of cooking and, more particularly, to a control system for a cooking appliance which enables the appliance to be selectively operated in a cold start cooking mode.  
           [0003]    2. Discussion of the Prior Art  
           [0004]    Conventional cooking appliances generally perform cooking operations through radiant heat developed from bake and/or broil heating elements. Such types of cooking appliances can take various forms, mainly ranges and wall ovens. When utilizing a conventional cooking appliance, the oven is initially controlled to proceed through a preheat cycle in order to establish a desired cooking temperature. Oftentimes, a signal is provided to a user when the preheat cycle is complete in order to indicate when the food to be cooked can be placed in the oven. In some cases, both the bake and the broil elements are actuated during the preheat cycle. In addition, it is also known to incorporate an internal fan in an oven for more evenly distributing developed heat. Convection systems are actually quite prevalent in microwave and other types of ovens which do not require preheating. However, utilizing convection systems in cooking appliances employing bake and broil elements is also known.  
           [0005]    Regardless of the type of overall heating system utilized, it is not uncommon for a consumer to place food into an oven for a predetermined cook time without first enabling the oven to reach a preheat temperature. Since cooking times set forth in recipes or other cooking instructions are established based on an oven being preheated, failure to preheat the oven directly affects the overall food preparation. Under such circumstances, the user must either mentally determine a supplemental cooking time period for the food item or, if the cook time is not altered, the food will be at least slightly undercooked.  
           [0006]    Based on the above, there exists a need in the art for a system which will enable a consumer to readily alter an established cooking operation when it is known that an oven is not going to be allowed to reach a preheat temperature prior to placing food in the oven. In other words, under conditions wherein a cold start cooking operation is to be performed, it would be beneficial to enable the consumer to easily alter a programmed cooking operation to automatically compensate for the lack of a preheat cycle.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to a control system for a cooking appliance which enables a consumer to perform a complete cooking operation regardless of whether food is placed into an oven after a preheating operation or from a cold start. In general, the invention enables a consumer to program a cooking appliance through a control panel in a conventional manner based on established cooking times and temperatures in accordance with recipes or other cooking instructions. However, under circumstances wherein the consumer does not intend to allow the oven to be properly preheated prior to inserting the food to be cooked therein, an additional control sequence can be performed by the user, such as the selection of a cold start feature. Thereafter, the control system for the cooking appliance will automatically alter the overall cooking operation to compensate for the lack of a preheat stage.  
           [0008]    In accordance with the most preferred form of the invention, an additional button is provided on a programming pad of the control panel for the cooking appliance, wherein the consumer need only press the additional button when a cold start cooking operation is to be employed. In one embodiment, when a cold start cooking operation is selected, the control system of the cooking appliance establishes a peak temperature for the oven which is well above a temperature set by the user for the overall cooking operation. After the peak temperature is reached, the oven temperature is allowed to gradually reduce, with a lattermost portion of the established cooking time actually operating the oven at the preprogrammed cooking temperature.  
           [0009]    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  
       [0010]    [0010]FIG. 1 is a partial perspective view of an electric range incorporating a cold start cooking system according to the invention;  
         [0011]    [0011]FIG. 2 is a front view of a control panel, forming part of the range shown in FIG. 1, including a schematic illustration of a control arrangement that forms part of the cold start cooking system; and  
         [0012]    [0012]FIG. 3 is a graphical representation of the temperature of the oven cavity when heated in accordance with the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    With initial reference to FIG. 1, the invention is illustrated for use in connection with an electric range, generally indicated at  2 . In the embodiment shown, electric range  2  includes a cabinet  5  within which is arranged an oven cavity  8  having an associated lower heating element  9  and a door  10 , shown in an open condition wherein access to oven cavity  8  is permitted. The following description assumes that heating element  9  is of a conventional electric heating element design, but it is considered within the scope of this invention that heating element  9  may be a gas heating element or of any other conventional design. This figure also illustrates the presence of a viewing window  11  in door  10 . Furthermore, within oven cavity  8 , a fan  12  and an upper, broil heating element, a part of which is shown at  14 , are provided. In a manner known in the art, cabinet  5  is provided with a light switch  16  which functions to turn on a light (not shown in FIG. 1 but indicated at  17  in FIG. 2) to illuminate oven cavity  8  upon the opening of door  10 .  
         [0014]    Cabinet  5  is also provided with an associated range top  18  which supports various spaced surface heating elements  20 - 23  in a manner known in the art. At an upper rear portion, cabinet  5  is provided with a control panel  28 . Control panel  28  includes a plurality of knobs  36 - 39  for use in selectively activating and deactivating surface heating elements  20 - 23  respectively. In addition, control panel  28  is shown to include a central display  44 , such as an LED or LCD display unit (also see FIG. 2). Furthermore, control panel  28  is provided with a number pad, generally indicated at  46 , having buttons for the numbers zero ( 0 ) through nine ( 9 ), with the zero ( 0 ) button also functioning as a reset control button.  
         [0015]    Although the particular features incorporated into electric range  2  could vary greatly within the scope of the present invention, for the sake of completeness in describing a preferred form of the invention, control panel  28  of range  2  is also shown to include a lower row of control buttons, generally indicated at  48 , which are provided to select various operational modes for range  2 . For instance, the row of control buttons  48  can be used to select bake, broil and clean modes for range  2  through respective buttons  49 - 51 . In the particular embodiment shown, an additional convection baking mode, which is essentially defined by a baking mode with the further activation of fan  12 , can also be selected through button  53 .  
         [0016]    In another form of the invention, the user may program the operation of range  2  through the use of the lower row of control buttons  48 , control button  53  and numeric pad  46 , as well as timer buttons  62  and  63 . Furthermore, buttons  66  and  67  are provided to enable a consumer to set desired countdown and clock times, in combination with numeric pad  46 , respectively. Button  68  performs a stop or clear control function, while button  69  enables a consumer to turn on light  17  without opening door  10  such that oven cavity  8  can be selectively viewed through window  11 . Button  70  is provided to initiate the cold start function in accordance with this invention as will be described below. Finally, an Auto Set button  72  is provided and can be used to perform various programming functions as will also be discussed below. Of course, although various buttons are described for use on control panel  28 , other types of control members, including a wide range of switches, could equally be employed. In addition, although the invention is being described with reference to range  2 , it should be recognized that the invention is applicable to various types of cooking appliances, including wall ovens and the like.  
         [0017]    [0017]FIG. 2 shows control panel  28  including an associated CPU  75  for controlling fan  12  and the heat sources of range  2 , i.e., at least illustrated heating elements  9 ,  14  and  20 - 23 . CPU  75  also includes cold start circuit  78  which is activated through button  70  as will be more fully discussed below. The operation of light  17  and heating elements  20 - 23  is performed in a manner known in the art, does not constitute part of the present invention and therefore will not be discussed further here. However, it will be mentioned that Auto Set button  72  can be used to assist the user in programming a cooking operation for range  2 . For example, if bake button  49  is selected, the operating temperature can be set directly through number pad  46  or by pressing Auto Set button  72  once for a certain starting temperature, e.g. 350° F. (177° C.), and subsequently for adding a set temperature value, e.g. 25° F., upon each further depression of button  72 . If a broil operation is selected through button  50 , Auto Set button  72  can be used to toggle between “Hi” and “Low” settings for heating element  14 . In any event, this operation is known in the art and only provided for the sake of completeness. Instead, the present invention is particularly directed to the manner in which CPU  75  is programmed to cause heating of oven cavity  8  upon the selection of the cold start feature by a user through button  70 . More particularly, cold start circuit  78  of CPU  75  operates in accordance with the present invention to assure that a complete cooking operation is performed on a food item placed within oven cavity  8  even though oven cavity  8  is not properly preheated.  
         [0018]    In using range  2 , a consumer may select a desired cooking function or operational mode through control buttons  49 ,  50  and  53 , while also establishing an operating time period for the respective heat source utilizing numeric pad  46  and timer buttons  62  and  63 . Again, numeric pad  46  or Auto Set button  72  can be used to set certain operating parameters as well. In one embodiment, the selected operation will be shown by illuminating key words or symbols in central display  44 . The preceding description is similar to the structure described in U.S. Pat. No. 6,153,858, the entire disclosure of which is herein incorporated by reference.  
         [0019]    It is preferable to employ some type of audible or visual indicator to the consumer when certain time periods have expired or certain temperatures have been reached. This function is performed by incorporating a piezoelectric buzzer or the like as indicated in FIG. 2 at  80 . For instance, as with a conventional cooking appliance, buzzer  80  is preferably used to indicate the end of a cooking operation. In addition, when range  2  is used in a more conventional mode wherein oven cavity  8  is permitted to preheat prior to the placing of food therein for cooking, buzzer  80  can signal a user at the end of the preheat stage.  
         [0020]    Of course, as indicated above, it is not uncommon for a consumer to place food into an oven for a predetermined cook time without first enabling the oven to reach a preheat temperature. Since cooking times set forth in recipes or other cooking instructions are established based on an oven being preheated, failure to preheat the oven directly affects the overall food preparation. However, in accordance with the present invention, the user need only press button  70  after programming a cooking operation wherein the user is not going to allow oven cavity  8  to preheat. Therefore, a signal is sent to CPU  75  that cold start circuit  78  is to be utilized in connection with the selected cooking operation. In general, when a cold start mode is selected, an actual cook time is calculated to arrive at an equivalent temperature and cook time associated with a preheat start. That is, cold start circuit  78  incorporates a control algorithm which functions to determine the required cold start time based on the cook time and temperature set by the user. This cold start time is then added to the cook time to arrive at an overall cooking operation time.  
         [0021]    As an example, if biscuits are recommended to be cooked at 475° F. for 12 minutes and the cold start selector button  70  is pressed, CPU  75  would operate one or more of heat sources  9  and  14 , perhaps even with fan  12 , in a cold start mode for an extended period of time, such as 15 minutes. This additional time would compensate for the user placing the food in oven cavity  8  and initiating the cooking operation without allowing oven cavity  8  to reach its preheat temperature. Ultimately, the total cooking time is reduced by eliminating the preheat stage.  
         [0022]    Certainly, there are various ways in which the invention can accomplish the goal of allowing a user to readily select a cold start control feature, thereby establishing an intelligent, easy and efficient use of range  2 . Of course, the actual preheat time for oven cavity  8  will be determined by the food load placed therein. That is, the more food placed in oven cavity  8 , the longer a requisite preheat time. Correspondingly, when a cold start operation is selected, the amount of time added to the preprogrammed cooking time should effectively vary with the food load. In accordance with the most preferred form of the invention, the actual time added based on a cold start is established based on an integration of the area under a set temperature and above a preheat curve.  
         [0023]    To this end, FIG. 3 represents a time/temperature curve associated with the use of oven cavity  8  in cooking a food item for 60 minutes at 350° F. That is, the food has already been placed in oven cavity  8  and a cooking operation for 350° F. for 60 minutes has been programmed. Depending on the food load, oven cavity  8  will reach the set temperature in a certain period of time, say 15 minutes. CPU  75 , in combination with cold start circuit  78 , would then establish a peak temperature to be reached in oven cavity  8 . In the example shown, this peak or overshoot temperature equals 50° F. above the 350° F., i.e., 400° F. The cooking operation would then proceed to reduce this temperature down to the programmed temperature over a portion of the overall cooking operation, with this portion being equal to ¼ or 15 minutes in the example provided. The remaining time in the overall cooking operation would be at the programmed 350° F. temperature. Of course, due to the activation/deactivation periods of the heat source(s)  9 ,  14 , the actual temperature in oven cavity will fluctuate about this set temperature as clearly represented in FIG. 3.  
         [0024]    Although described with reference to a preferred embodiment of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, even though the invention has been described as employing a special button on the control panel for the cooking appliance to establish the cold start cooking sequence, other control arrangements could be equally employed, including the activation of two or more other buttons simultaneously. In addition, although the invention has been described in connection with an electric cooking appliance, the invention could be employed in a wide range of cooking appliances, including gas and/or convection ovens, including those also incorporating microwave or other heat sources. Of course, control panel  28  can take various forms and configurations in accordance with the invention. Furthermore, it should be recognized that the line in FIG. 3 only represents a typical temperature progression in accordance with the invention, and that a variety of other graphs may result. In general, the invention is only intended to be limited by the scope of the following claims.