Abstract:
A method of operating a refrigerated oven to cook a food item therein comprises the steps of A) determining the temperature of the cooking chamber in the refrigerated oven, B) producing cooled air in the refrigeration unit of the refrigerator oven for a first period of time if the temperature of the cooking chamber is below a predetermined threshold temperature and delaying production of cooled air in the refrigeration unit if the temperature of the cooking chamber is not below the predetermined threshold temperature, C) circulating the cooled air through a refrigerated air path to the cooking chamber to prevent spoilage of the food item, and, D) heating the cooking chamber to cook the food item in the cooking chamber by cycling the heating element for a second time period.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     While previous refrigerated ovens attempt to address the problem of preventing the food from spoiling before the initiation of the bake cycle, they do not address the problem of maintaining the cooked food at a temperature suitable for serving after the completion of the Time-Bake cycle, which can result in the need to warm the cooked food if the user does not remove and serve the food immediately at the completion of the bake cycle, such as when the user unexpectedly had to work late or was delayed in arriving home. 
     2. Description of the Related Art 
     Ovens for cooking or baking foods are ubiquitous. While various ovens may have a variety of different features and cooking cycles, almost every contemporary oven includes a cooking chamber for receiving the food to be cooked and a heat source for heating the cooking chamber to a user-selected cooking temperature for a user-selected time-period. The heat source is normally one or more electric or gas heating elements positioned within the cooking chamber. Some ovens use a magnetron to generate microwaves as the heat source. A variety of controllers, including user input devices and displays, enable the user to input the preferred cooking temperature and cooking time. 
     A common cooking cycle is a Time-Bake cycle where the user can control the start time and stop time of the cooking cycle. A common application for the Time-Bake cycle is for cooking food while the user is away from the home, such as at work, and the cooking of the food will be completed at the anticipated arrival of the user at home, such as when the user returns home from work. The advantage of a Time-Bake cycle is that the user can cook the food without being present and have the food ready upon the user&#39;s anticipated time of arrival. 
     A disadvantage of the use of a Time-Bake cycle with an oven lies in that the cooking time for most food is substantially less than the amount of time the user is away, necessitating that the food be placed in the cooking chamber several hours before the start time of the cooking cycle. For example, most foods are cooked within 2-3 hours while most users work a traditional 8-hour day, excluding commute time, which requires that the food be placed in the cooking chamber at least five hours prior to the start time of the Time-Bake cycle. Not all food can be placed in the oven for long time periods without spoiling. Many types of food suitable for cooking in the oven require continuous refrigeration prior to cooking. These foods can spoil prior to the initiation of the start time of the Time-Bake cycle. 
     An attempt to solve the problem of food spoiling while placed in the cooking chamber during the delay prior to the start of the Time-Bake cycle included the addition of a refrigeration unit with the oven to cool the cooking chamber prior to the initiation of the bake cycle. Such a combination refrigerator oven is disclosed in U.S. Pat. No. 4,884,626 to Filipowski. 
     While previous refrigerated ovens attempt to address the problem of preventing the food from spoiling before the initiation of the bake cycle, they do not address the problem of maintaining the cooked food at a temperature suitable for serving after the completion of the Time-Bake cycle, which can result in the need to warm the cooked food if the user does not remove and serve the food immediately at the completion of the bake cycle, such as when the user unexpectedly had to work late or was delayed in arriving home. The Filipowski patent addresses the spoilage of the cooked food after the completion of the time-bake by starting a cooling cycle to refrigerate the cooked food upon the passing of a predetermined time from the completion of the time-bake as long as the oven door was not opened. However, the Filipowski patent does not address maintaining the cooked food at a temperature suitable for serving upon completion of the bake cycle. 
     There is an unfilled need for a refrigerated oven that not only protects the food from spoiling, both before and after the bake cycle, but also maintains the cooked food at a temperature suitable for serving after the completion of the bake cycle. 
     In addition to the shortcomings associated with the various cooking cycles, prior refrigerated ovens have structural shortcomings related to the inherent difficulties of combining a traditional refrigeration system with a traditional oven, which have antithetical functions: one heats and one cools. These problems can vary and most notably include: the difficulty of transferring the chilled air from the refrigeration unit into the cooking chamber, finding sufficient space in the standard-size oven for the refrigeration unit, and providing easy access to the refrigeration unit for maintenance. 
     An especially difficult problem related to incorporating a refrigeration unit with an oven is protecting the refrigeration system and its components from the high heat generated by the oven. This problem is exacerbated by the high temperatures attained during an oven cleaning cycle; these temperatures are approximately 850° F. Such heat creates an environment capable of damaging or negatively impacting the performance of a traditional refrigeration unit. For example, the temperature surrounding the refrigeration unit can be sufficiently great enough to negatively impact a traditional refrigeration system, which greatly reduces the life of the refrigeration unit or may cause the system to prematurely fail. Thus, the refrigeration unit must be capable of functioning properly when placed in close proximity to the self-cleaning oven. 
     SUMMARY OF THE INVENTION 
     The invention relates to a method of operating a refrigerated oven to cook a food item placed therein. The refrigerated oven is comprised of several components such as a cooking chamber having a heating element for heating the cooking chamber, a refrigeration unit for cooling the cooking chamber, a temperature sensor for sensing the temperature of the cooking chamber, a data input device for inputting user-selected cooking cycle parameters, and a controller operably coupling and controlling the components of the refrigerated oven to selectively actuate heating element and the refrigeration unit in response to the sensed temperature to thereby implement the method as defined by the cooking cycle parameters. 
     The method comprises the steps of: A) cooling the cooking chamber to prevent the spoiling of the food item in the cooking chamber by cycling the refrigeration unit for a first time period; B) heating the cooking chamber to cook the food item in the cooking chamber by cycling the heating element for a second time period; and C) delaying the initiation of step A until the temperature of the cooking chamber cavity is below a predetermined threshold temperature. Preferably, the predetermined threshold temperature is about 170 degrees F. 
     The operation of the refrigerated oven is preferably terminated if the initiation of step A is delayed beyond the predetermined time. Preferably, during the cooling of the cooking chamber, the temperature is maintained at a first predetermined temperature, which is preferably set by the controller. During the cooking of the food item, the temperature of the cooking chamber is maintained at a second predetermined temperature, which is preferably inputed by the user. 
     After the completion of cooking step B, the cooking chamber is heated to maintain the food item at a temperature suitable for serving upon removal from the cooking chamber by cycling the heating element for a third time period. During this warming of the food item, the cooking chamber is preferably maintained at a third predetermined temperature, which is preferably set by the controller. Preferably, the warning step is automatically initiated at the end of the cooking step and is terminated upon the opening of the oven door. 
     The first time period can be determined based on at least one cooking cycle parameter inputted by a user. Preferably, two cooking cycle parameters are inputted, an End Time, corresponding to the time that the bake cycle is to be completed, and a Bake Time, corresponding to the length of time for cooking the food item. The first time period is determined by subtracting the Bake Time from the End Time. The second time period is preferably set equal to the Bake Time. 
     The cooling step can include several sub-steps. For example, if the temperature of the cooking chamber does not cool down to a predetermined threshold within a predetermined time period, the cooling step can be terminated. 
     An optional second cooling step can follow the warming step. The second cooling step preferably is initiated after the warming step and then activated for a predetermined time period. The second cooling step can be terminated upon the opening of the oven door. 
     In a second embodiment, the invention relates to a method of operating a refrigerated oven to cook a food item therein. The refrigerated oven comprises a cooking chamber having a heating element for heating the cooking chamber in combination with a refrigeration unit for cooling the cooking chamber. A temperature sensor is provided for sensing the temperature of the cooking chamber. A data input device is provided for inputting user-selected cooking cycle parameters. A controller operably couples the heating element, refrigeration unit, temperature sensor, and the data input device to selectively actuate the heating element and the refrigeration unit in response to the sensed temperature to implement the method as defined by the cooking cycle parameters. 
     The method includes the steps of: A) cooling the cooking chamber to prevent the spoiling of the food item in the cooking chamber by cycling the refrigeration unit for a first time period; B) heating the cooking chamber to cook the food item in the cooking chamber by cycling the heating element for a second time period; and C) terminating step A if the cooking chamber does not reach a predetermined threshold temperature within a predetermined time period. Preferably, the predetermined threshold temperature is 40° F. 
     The method can further include after the completion of step B, a step D comprising the heating the cooking chamber to maintain the food item at a temperature suitable for serving upon removal from the cooking chamber by cycling heating element for a third time period. Step D is preferably automatically initiated after step B and terminates upon the opening of the oven door. An optional cooling step E can follow the warming step D. The cooling cycle step E is preferably automatically initiated after step D and terminates upon the opening of the oven door. 
     In yet another embodiment, the invention relates to a time-bake cooking cycle for a refrigerated oven used to cook food items therein. The refrigerated oven comprises several components such as a cooking chamber having a heating element for heating the cooking chamber, a refrigeration unit for cooling the cooking chamber, a temperature sensor for sensing the temperature of the cooking chamber, a data input device for inputting user-selected cooking cycle parameters, and a controller operably coupling and controlling the components of the refrigerated oven to selectively actuate heating element and the refrigeration unit in response to the sensed temperature to thereby implement the time-bake cooking cycle as defined by the cooking cycle parameters. 
     The time-bake cooking cycle comprises: a cool cycle, a bake cycle, and a warm cycle. During the cool cycle, the temperature of the cooking chamber is maintained at a first predetermined temperature to prevent the spoiling of the food item in the cooking chamber. The bake cycle maintains the temperature of the cooking chamber at a temperature sufficient to cook the food item in the cooking chamber. During the warm cycle, the temperature of the cooking chamber is maintained a temperature suitable for serving the food item upon removal therefrom and is terminated upon the opening of the oven door. 
     The cool cycle, bake cycle and warm cycle are preferably sequentially initiated. The bake cycle can be automatically initiated after the completion of the cool cycle. The warm cycle can be automatically initiated after the completion of the bake cycle. An optional second cool cycle can follow the warm cycle, and can be terminated upon the opening of the oven door. Similarly, the warm cycle can also be terminated upon the opening of the other door. 
     A data input cycle is preferably provided to permit user-defined operating parameters to be stored in the controller. Preferably, the user-defined operating parameters comprise an End Time, representing the time of day that the cooking of the food is to be completed, and a Bake Time, representing the length of time to cook the food. The bake cycle is preferably initiated at the time of day corresponding to the End Time minus the Bake Time. 
     The initiation of the cool cycle can be delayed as long as the temperature of the cooking chamber is above the predetermined threshold temperature. Preferably, the time-bake cooking cycle is aborted if the temperature of the cooking chamber remains above the predetermined threshold temperature for a predetermined time period. The cool cycle can also be terminated if the temperature of the cooking chamber does not fall below a predetermined threshold temperature after a predetermined time period. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of the refrigerated oven according to the invention and illustrates the chassis or frame of the oven in which are formed a cooking chamber and a refrigeration unit chamber, with a door (shown in phantom) for closing the cooking chamber shown in an open position, a modular refrigeration unit partially inserted within the refrigeration unit chamber, and a cover for the refrigeration unit chamber. 
         FIG. 2  is a perspective view of the chassis with the modular refrigeration unit inserted within the refrigeration unit chamber. 
         FIG. 3  is a perspective view identical to  FIG. 2  except the modular refrigeration unit is not shown to better illustrate cold air and return ducts fluidly connecting the cooking chamber and the refrigeration unit chamber. 
         FIG. 4  is a sectional view taken along line  4 — 4  of  FIG. 3  illustrating the cold air and return ducts. 
         FIG. 5  is an exploded view of the modular refrigeration unit shown in FIG.  1  and illustrating the components of the modular refrigeration unit mounted to a base. 
         FIG. 6  is a right-front perspective view of the assembled modular refrigeration unit with an insulation cover placed over an evaporator assembly. 
         FIG. 7  is a left-rear perspective view of the assembled modular refrigeration unit and illustrates the cold air and return air openings in the insulation cover. 
         FIG. 8  is identical to  FIG. 6 , except that the insulation cover is removed to illustrate the evaporator assembly, including an insulation pad. 
         FIG. 9  is a perspective view of the base of the modular refrigeration unit with an integrally formed evaporator pan. 
         FIG. 10  is a perspective view of the insulation pad for insulating an evaporator from a base of the modular refrigeration unit, with the insulation pad forming a condensation catch pan and a drain channel. 
         FIG. 11  is a schematic of a generic controller for controlling the operation of the oven heating element and refrigeration unit in response to temperature sensor input and user-selected input received by the controller from an input/display device. 
         FIG. 12  is a schematic of a preferred main cycle of operation for the refrigerated oven comprising the cycles or steps of Data_Input, Cool_Cycle, Bake_Cycle, and then Warm_Cycle, followed by an optional Cool_Cycle. 
         FIG. 13  is a schematic of a Data_Input step for setting the parameters of the preferred Time_Bake_Cycle. 
         FIG. 14  is a schematic of the steps or cycles for the Cool_Cycle, which includes a Cooking Chamber Temp. Check, a Refrigeration System Check, and a Cooling_Cycle. 
         FIG. 15  is a schematic of Cooking Chamber Temp. Check for determining whether the temperature of the cooking chamber is within the operational range prior to the initiation of the modular refrigeration unit. 
         FIG. 16  is a schematic of Refrigeration System Check for determining if the refrigeration unit is functioning properly during the initiation of the Cooling_Cycle. 
         FIG. 17  is a schematic of the Cooling_Cycle for maintaining the temperature of the cooking chamber at a predetermined cooling temperature. 
         FIG. 18  is a schematic of the Bake_Cycle for baking food placed in the cooking chamber. 
         FIG. 19  is a schematic of a Warm_Cycle for maintaining cooked food at a temperature suitable for serving for a predetermined time after the completion of the Bake_Cycle. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1-3  illustrate the refrigerated oven  10  according to the invention and comprising a chassis or frame  12  that defines a cooking chamber  14  and a refrigeration unit chamber  16 , which are arranged in a stacked configuration with the refrigeration unit chamber  16  positioned below the cooking chamber  14 . An external skin or cabinet  18  is mounted to the frame  12  and forms a decorative exterior for the refrigerated oven  10 . A modular refrigeration unit  20  is slidably received within the refrigeration unit chamber  16 . 
     The frame  12  functionally comprises a front  24 , rear  26 , top  28 , bottom  30 , and opposing sides  32 ,  34 . The cooking chamber  14  and the refrigeration unit chamber  16  both have open faces  38 ,  40 , respectively, which open onto the front  24  of the frame  12 . 
     The cabinet  18  preferably comprises decorative side panels  42 ,  44  and top panel  46 , which overlay the corresponding sides  32 ,  34  and top  28  of the frame  12 , respectively. The rear  26  and bottom  30  of the frame  12  are not typically covered by a decorative panel. A rear panel  48  typically overlies and covers the rear  26  of the frame  12 . While not germane to the invention, a series of burners  50  are disposed on the top  28  of the frame  12  and extend through corresponding openings in the top panel  46 . The burners collectively form a cooktop. 
     An oven door  56  (shown in phantom in an open position) is hingedly mounted to the front  24  the frame  12  and is movable between an open and a closed position. In the open position, the door  56  is removed from the open face  38  of the cooking chamber  14  and provides access to the interior of the cooking chamber  14 . In the closed position, the door  56  overlies the open face  38  and blocks access to the interior of the cooking chamber  14 . A door position sensor  58 , illustrated as a spring-biased, push-button switch, is provided on the front  24  of the frame. When the door is in the closed position, the push-button switch is depressed to indicate the door is closed. 
     A cover  60  for the refrigeration unit chamber  16  is removably mounted to the front  24  of the frame  12  and closes the open face  40  of the refrigeration unit chamber when mounted to the frame  12 . The cover  60  can be removed to gain access to the modular refrigeration unit contained within the interior of the refrigeration unit chamber  16 . 
     The cooking chamber  14  comprises opposing side walls  64 ,  66  that are connected along their upper and lower edges by an upper wall  68  and lower wall  70 , respectively. A rear wall  72  closes the rear of the cooking chamber  14  opposite the open face  38 . A series of shelf supports  74  are formed in each of the side walls  64 ,  66  and are used in pairs to support one or more shelves (not shown) mounted within the cooking chamber  14 . 
     A heating element  75 , illustrated as gas heating element, is positioned within the cooking chamber  38  adjacent the bottom wall  70 . The type of heating element is not germane to the invention. Any type of heating element can be used, including electric or gas heating elements, for example. There can also be multiple heating elements positioned within the cooking chamber  38 . If multiple heating elements are used, traditionally, one is placed adjacent the lower wall  70  and the other is place adjacent the upper wall  68 . A temperature sensor  77  ( FIGS. 2 and 10 ) is also positioned within the cooking chamber  38  for monitoring the temperature therein. 
     The refrigeration unit chamber  16  functionally has the same configuration as the cooking chamber  14  in that the frame functionally defines side walls  76 ,  78 , whose upper edges are connected by a top wall  80 , and whose rear edges are connected by a rear wall  82  to thereby form a chamber with an open face  40  and an open bottom  84 . Typically, the top wall  80  of the refrigeration unit chamber  16  is spaced from the lower wall  70  of the cooking chamber  14  and the heating element  75  is disposed therebetween. 
     Referring to  FIGS. 3 and 4 , the cooking chamber  14  and refrigeration unit chamber  16  are fluidly connected by a cold air duct  90  and a return duct  92 . An inlet  94  for the cold air duct  90  is located on the side wall  76 . An outlet  96  for the cold air duct  90  is located on the side wall  64  of the cooking chamber  14  at an upper portion thereof and at the junction of the side wall  64  with both the rear wall  72  and the top wall  68 . An inlet  98  for the return duct  92  is located at a lower portion of the rear wall  72  for the cooking chamber  14  at the junction of the rear wall  72  with the side wall  64  and the bottom wall  70 . An outlet  100  for the return air duct  92  is located in the rear wall  82  of the refrigeration unit chamber  16 . 
     The location of the cold air duct  90  and the return duct  92  and their corresponding inlets and outlets result in an air flow circulation path, hereinafter referred to also as a “refrigerated air path,” identified by the flow lines A. Assuming the air flow began at the inlet to the cold air duct  90 , the air flow circulation path A will proceed (in a clockwise motion as viewed in  FIG. 3 ) through the cold air duct  90  and enter the cooking chamber  14  through the cold air duct outlet  96  where it is directed toward the opposing side wall  66 . Ultimately, the cold air entering the cooking chamber  14  through the cold air duct outlet  96  will enter the inlet  98  to the return air duct  92  and exit the return air duct outlet  100 , where the air is once again chilled by the modular refrigeration unit  20  and re-circulated. 
     The location of the cold air duct outlet  96  and the return duct inlet  98  enhances the circulation of the cold air around the cooking chamber  14 . First, the force of the cold air exiting the cold air outlet  96  will inherently direct the cold air toward the opposing side wall  66  where, upon contact with the side wall  66 , the cold air will be deflected back towards the side walls  64  and the return air duct inlet  98 . Second, the cold air exiting the cold air duct outlet  96  is typically colder and more dense than the air in the cooking chamber  14 , the denser cold air will inherently fall towards the bottom wall  70  of the cooking chamber  14 . Since the cold air duct outlet  96  is located at the top of the cooking chamber  14 , the naturally denser cold air exiting the cold air duct outlet  96  will automatically generate circulation from the top toward the bottom of the cooking chamber  14 . Third, the modular refrigeration unit  20  forms a relatively low pressure in the return duct  92 , which naturally draws the already redirected and falling cold air toward and into the return duct inlet  98 . 
     The return duct outlet  100  has a generally rectangular shape and faces the open face  40  of the refrigeration unit chamber  16 . The cold air inlet  94  is generally orthogonal to the open face  40 . A side portion  108  of the cold air duct  90  is movably mounted to the remainder of the duct. The side portion  108  is preferably hingedly mounted to the cold air duct  90  by any suitable method. For example, the side portion  108  could be a separate piece of material having an upper end that is taped to the cold air duct. Alternatively, since the cold air duct is preferably made from thin metal such as sheet metal, the side portion  108  could be an elongated tab cut from cold air duct  90  and the hinge is formed by bending the tab relative to the rest of the duct. 
     Referring to  FIGS. 5-8 , the modular refrigeration unit  20  comprises a base  120  on which are mounted a compressor  122 , condenser assembly  124 , an evaporator assembly  126 , and a dual-blade fan  128 , which is shared by the condenser assembly  124  and evaporator assembly  126 . Since all of the components for the modular refrigeration unit  20  are mounted on the base  120 , the modular refrigeration unit  20  is easily slid into and out of the refrigeration unit chamber  16  to simplify the installation and maintenance of the modular refrigeration unit  20 . 
     The dual-blade fan  128  includes a motor  129  with a shaft  133 . A compressor blade  130  and an evaporator blade  132 , each mount on the shaft  133 . A thermally non-conductive spacer  135  separates the motor  129  from the evaporator assembly  126  to thermally isolate the evaporator assembly from the fan motor  129 . Although not shown as such in  FIG. 5 , the evaporator blade  132  is received within the evaporator assembly  126  when assembled. 
     Referring to  FIG. 9  specifically and to  FIGS. 5-8  generally, the base  120  is preferably made from a thermally conductive material, such as stainless steel, for example. An evaporator pan  134  is formed in the base  120 . The evaporator pan  134  is preferably a depression formed in the base  120 , such as by a press. However, the evaporator pan  134  could be a separate piece mounted to the base  120 , including mounted to a corresponding opening in the base  120 . Compressor mounting fingers  136  extend upwardly from the base  120  and cooperate with the compressor  122  to mount the compressor to the base  120 . 
     As illustrated, the compressor mounting fingers  136  are formed by cutting and bending portions of the base. Is also contemplated that separate fingers  136  can be affixed to the base if and when it is not desirable to have openings in the base, such as when it is desired to use the entire base as the evaporator pan  134 . The outer edges of the base  120  turn upwardly to form a peripheral rim about the base  120  to aid in retaining any liquid overflow from the evaporator pan  134 . 
     Referring to  FIGS. 5-8 , the compressor  122  is a traditional compressor and any suitable compressor can be used for the invention. A suitable compressor is a hermetic reciprocating compressor manufactured by Embraco, model EM65. The compressor sets on a mounting bracket  138  that has openings for receiving the compressor mounting fingers  136  to thereby secure the compressor  122  to the base  120 . 
     The condenser assembly  124  comprises a condenser  142  and fan shield  144 , which includes a fan opening  148  through which passes the condenser fan blade  130 . Both of the condenser  142  and fan shield  144  are mounted to the base  120  by heat conductive spacers, such as aluminum spacers  146 , which conduct the heat from the condenser  142  to the base  120 . Since the condenser  142  rejects a substantial amount of heat during the refrigeration cycle, the heat is immediately conducted to the base  120 , including the evaporator pan  134 , to aid in the evaporation of any water in the evaporator pan  134 . The use of the conducted condenser heat to evaporate the liquid in the evaporator pan  134  is enhanced by the evaporator pan being made from a thermally conductive material. 
     The evaporator assembly  126  comprises an evaporator  150  and a fan shield  152 , which includes a fan opening  154  through which the fan blade  132  is received. A mount  158  thermally isolates and connects the evaporator  150  and the fan shield  152  to the base  120 . A housing  160 , comprising opposing side portions  162 ,  164  and top wall  166 , overlies the evaporator  150  and the fan shield  152  and rests on the mount  158  to enclose the evaporator  150  and fan shield  152 . An insulation box  168  overlies the housing  160  and comprises complementary halves  170 ,  172 , which are slidably coupled to encase the housing  160 . 
     The mount  158  is preferably thermally non-conductive to prevent the heat of the base  120  from being conducted to the evaporator  150 . The mount  158  preferably comprises an insulation pad  176  and spacers  178 , which are received within openings or recesses in the insulation pad  176 . The spacers  178  are arranged in two triangular sets. The innermost spacers of each set connect the evaporator  150  to the base and the remaining spacers connect the side portions  162 ,  164  to the base the  20 . The spacers are preferably made from Nylon and the insulation pad  176  is preferably made from expandable foam. 
     Referring specifically to FIG.  10  and generally to  FIGS. 5-8 , the insulation pad  176  comprises several topographical features that perform important functions for the invention. A recess forming a catch pan  182  is formed in the upper surface of the insulation pad  176  at a location below where coils for the evaporator  150  will be located when the evaporator  150  is mounted. Thus, any condensation dripping from the coils of the evaporator will fall into the catch pan  182 . An open-top channel  184  extends from the catch pan  182  through a peripheral edge of the insulation pad  176 . The channel  184  slopes downwardly from the catch pan  182  to the peripheral edge and carries away any liquid collecting in the catch pan  182  and directs it to the evaporator pan  134 . 
     Advantageously, the insulation pad  176  is mounted to the base  120  such that the channel  184  extends between the fan blades  130 ,  132 . The airflow generated by the fan blades  130  passes below the insulation pad and aids in evaporating any liquid in the evaporator pan sump  134 . The condenser fan blade  130  is especially helpful in evaporating water in the evaporator pan  134  since the condenser fan blade  130  draws the warm air from the condenser across the evaporator pan  134 . 
     The side portions  162 ,  164  of the housing  160  each include an opening  188 ,  190 , through which is inserted a peripheral flange  192 ,  194 , respectively. A peripheral seal  196  and peripheral gasket  198  encircle the flanges  192 ,  194 , respectively. The peripheral flanges  192 ,  194  are adapted to mate with the cold air duct inlet  94  and the return outlet  100 , respectively, to fluidly couple the interior of the housing  160  with the cold air duct  90  and return duct  92 . 
     The seal  196  and gasket  198  are located on the flanges  192 ,  194  such that they fluidly seal the evaporator housing  160  with respect to the cold air duct  90  and return duct  92  upon the sliding insertion of the modular refrigeration unit  20  within the refrigeration unit chamber  16 . Specifically, the peripheral flange  194  is received within the outlet  100  of the return air duct  92  and the gasket  198  is compressed between the housing side wall  164  and the duct  92  to form a fluid seal therebetween. The seal  196  is slidably received within the open side edge of the cold air duct  90  formed by the hinged movement of the side portion  108  to an open position. When the modular refrigeration unit is completely received within the refrigeration unit chamber  16 , the seal  196  abuts the inner edge of the inlet  94 . The side portion  108  is then hinged to a closed position where it overlies the seal  196  and the side portion  108  is then secured to the return duct  192 , preferably by a suitable fastener such as a pop in rivet or a screw. 
     The side portion  164  includes a fan shaft opening  195  that is sized to receive the shaft  133  from the fan  128 . A thermally non-conductive spacer  135  is positioned between the side portion  164  and the fan  128  to minimize the fan  128  from conducting heat to the side portion  164  and thereby prevent the heat from negatively impacting the performance of the evaporator  150 . 
     The peripheral flange  194  and its corresponding opening  190  are positioned within the side portion  164  such that they are upstream of the airflow generated by the evaporator fan blade  132 . Correspondingly, the flange  192  and its corresponding opening  188  are positioned in the side portion  162  such that they are downstream of the airflow generated by the evaporator fan blade  132 . Therefore, the evaporator assembly  126  in combination with the cold air duct  90 , return duct  92 , and cooking chamber  14  define a chilled airflow path along previously described flow lines. Thus, the air flow generated by the evaporator fan blade  132  that passes through the evaporator  150 , the cold air duct  90 , the cooking chamber  14 , the return duct  92 , and back to the evaporator assembly  126 . 
     In a traditional manner, the output-side of the condenser  130  is connected to the input-side of the evaporator  150  through a capillary tube  197  to permit the build up of pressure in the condenser  130  so that the condenser  130  can convert the refrigerant gas into a liquid. Also, the output-side of the evaporator  150  is connected by a conduit  199  to the input-side of the compressor  122 . The output-side of the compressor is connected to the input-side of the condenser through a conduit  200 . The connection and operation of the compressor  122 , condenser  130 , and evaporator  150  of the modular refrigeration unit  20  are traditional and well-known, they will not be described in further detail. 
     The opposing halves  170 ,  172  of the insulation box  168  are preferably shaped to conform to the shape of the housing  160  while having appropriate openings to permit the passage of the various connectors for the compressor  122 , condenser  130 , and evaporator  150 . The insulation half  170  comprises a partial cold air duct opening  201  and partial fan opening  202 . Similarly, the insulation half  172  comprises corresponding partial cold air duct opening  204  and partial fan opening  206 , along with return duct opening  208 . When the insulation halves  170 ,  172  are assembled over the housing  160 , the partial cold air duct openings  200 ,  202  cooperate to encircle the peripheral flange  192  associated with the cold air duct  90 , the openings  202 ,  206  cooperate to encircle the fan  128 , and the return duct opening  208  encircles the peripheral flange  194  associated with the return duct  92 . 
     An advantage of the two-half insulation box  168  is that it is easily assembled over the housing  160  and can be unassembled as needed for maintenance. 
     The modular refrigeration unit  20  has a variety of features whose function enables the useful operation of the modular refrigeration unit  20  in the high temperature environment associated with the refrigerated oven  10 . One general category of features relate to the thermal isolation of the evaporator assembly  126  from the other components of the modular refrigeration unit  20  and from the rest of the refrigerated oven  10 . The features include the thermally non-conductive mount  176  that physically separates and thermally isolates the evaporator assembly  126  generally and the evaporator  150  specifically from the base  120 , which is advantageously used as a heat exchanger to dissipate heat from the condenser. The fan spacer  135  also functions to thermally isolate the evaporator assembly  126  from any heat that could be conducted through the fan  128  if it were to contact of the side portion  164  of the housing  160 . Additionally, the insulation box  168  thermally isolates all but the bottom of the evaporator assembly  126  from the rest of the refrigerated oven  10 , including the modular refrigeration unit  20 . The collective thermally-isolating effect of all of these structural features permit the useful operation of the modular refrigeration unit  20  and the high temperature environment of an oven. Without the thermally-isolating features, the performance of the evaporator  150  could be substantially impaired in the high temperature environment. 
     In addition to the thermally isolating features, the invention also addresses the higher than normal condensation that can exist when a refrigeration unit is used in a high temperature environment. Even though the evaporator  130  is insulated from the surrounding heat, the insulation cannot stop all heat reaching the evaporator. The generally higher ambient temperature surrounding the evaporator will increase the amount of condensation that must be removed. To handle the increased condensation, the catch pan  182  and channel  184  of the insulation pan  176  direct the liquid condensate from the evaporator directly onto the base  120  for evaporation. Since the base  120  functions as a heat exchanger, the additional heat carried by the base  120  in performing the heat-exchanging function also advantageously increases the rate of evaporation for the liquid condensate carried on the evaporation pan  134  of the base  120 . The location of the condenser fan blade  130  with respect to the insulation pan  176  and base  120  also aids in evaporating the liquid condensate on the base  120  and the air flow created by the condenser fan  130  is drawn below the evaporator pan  134  from the condenser  130 . This particular air flow path will result in an increased rate of evaporation for the liquid condensate in or the evaporator pan  134 . 
     To the extent the additional heat can be reduced, the resulting consequences described above will be minimized. Thus, the modular refrigeration unit  20  also includes several special features that relate to the dissipation of heat. The condenser  130  is directly connected to the thermally-conductive base  120  by thermally-conductive spacers  146  to aid in distributing the heat from the condenser to the base  120 , which functions as a heat exchanger. The thermally conductive spacers  146  improve the rate of conduction from the condenser to the base. And, the size of the base improves the dissipation of the conducted heat. Collectively, these features dissipate the heat from the condenser relatively quickly to reduce the heat convected to the surrounding air. 
     The many structures of the modular refrigeration unit  20  that permit it to thermally isolate the evaporator from the surrounding high temperature environment, to remove the generated condensation, and to dissipate the condenser heat, make the modular refrigeration unit  20  uniquely suited for the environment found in a refrigerated oven. 
       FIG. 11  illustrates one possible controller  220  for controlling the operation of the refrigerated oven  10  in accordance with a preferred cycle. The controller  220  preferably is a microprocessor-based controller that has programmable read-only memory in addition to the programmable memory of the microprocessor. The controller  220  typically will include an oscillator or other device that can be used as a clock to monitor the time of any aspect of the operation of the refrigerated oven  10 . 
     An input/display device  222  is provided and functions as a user interface for the user to input operational parameters for the refrigerated oven  10  as needed. The input/display device  222  also contains a display whereby the controller  220  can display to the user information or data necessary to operate the refrigerated oven  10  and all of the parameters needed to perform a particular cycle or function. The input/display device  222  can be any suitable such device. One of ordinary skill in the oven art is aware of many mechanical, electrical, or electro-mechanical input/display devices that can be used for the invention. Such input/display devices can range from simple manually-operated knobs or dials having information, such as time or temperature imprinted thereon, and which are set relative to a reference point to a catch-panel input device in combination with an LCD or other type of display. 
     The particular structure or type of controller  220  and input/display device  222  are not germane to the invention and therefore will not be described in greater detail. 
     The controller  220  is operably connected to the heating element  75  contained in the cooking chamber  14  of the modular refrigeration unit  20 . The controller is also connected to the temperature sensor  77  and the door sensor  58 . The controller  220  selectively cycles the heating elements and the modular refrigeration unit in response to the selected operating cycle as defined by the operational parameters stored in the memory of the controller or input and by the user through the input/display device  222  and further in response to the temperature sensed by the temperature sensor. 
       FIGS. 11-19  illustrate a preferred operating cycle  300  for use with the previously described refrigerated oven  10 . For purposes of this description the preferred operating cycle is in the genre of Time-Bake cycles. Also for purposes of this description, all of the operating parameters, whether stored in the memory of the controller or entered by the user, are generically referred to as predetermined, indicating a value is set or has been set for the parameter, even if the value is variable or dynamic. 
     The major steps or cycles of the preferred Time-Bake cycle for the refrigerated oven  10  begin with a Data_Input step  302  in which any necessary user-defined data is input to the controller  220 . The Data_Input step  302  is followed by the Cool_Cycle  304  where the modular refrigeration unit  20  is cycled to maintain the cooking chamber  14  at a temperature sufficient to prevent any food placed therein from spoiling before the initiation of the Bake_Cycle  306 , which follows the Cool_Cycle  304 . The Bake_Cycle  306  can be any type of Bake_Cycle. A preferred Bake_Cycle  306  is disclosed in U.S. patent application Ser. No. 09/838,447, the disclosure of which is incorporated by reference. The Bake_Cycle  306  is followed by a Warm_Cycle  308  that maintains the cooked food at a temperature suitable for serving upon removal from the cooking chamber  14 . An optional Cool_Cycle  310 , preferably substantially similar to the Cool_Cycle  304 , can follow the Warm_Cycle  308 . 
     Referring to  FIG. 12 , the preferred operating cycle  300  is in the form of a Time_Bake cycle where the food is placed in the cooking chamber  14  well before it is desired to begin the cooking of the food. In other words, the preferred operating cycle  300  includes a delay from the time the food is placed in the cooking chamber  14  until the desired time for the cooking cycle to begin. The delay can be caused by many different reasons. A typical example of such a situation is when the user desires to have food prepared and ready for dinner upon arrival at home after work but must place the food in the cooking chamber  14  in the morning before leaving for work. This example will be used to describe the operation of the preferred cycle  300 . 
     Referring to  FIG. 13 , the Data_Input step  302  begins at step  320  by requesting the user to enter the user-defined operating parameters for the preferred cycle  300 . The particular user-defined parameters will vary depending on the manner in which the preferred operating cycle  300  is implemented. However, under most implementations, a user will enter the time at which the cooking of the food is to be completed (the “End Time”), the length of time needed to cook the food (the “Cook Time”), and a temperature at which the food should the cooked (the “Bake Temp”). The user-defined data is then stored in the memory of the microprocessor. 
     The controller  220  at step  322  uses the user-defined End Time and the Cook Time to calculate the time at which the Bake_Cycle  306  should be started (the “Bake Start Time”) to complete the cooking of the food by the End Time. The calculation of the Bake Start Time is easily accomplished with the microprocessor of the controller  220 , which then stores the calculated Bake Start Time to initiate the cooking of the food for the Bake_Cycle  306 . Program control is then returned at step  324  to the preferred cycle  300 , which automatically advances to start the Cool_Cycle  304 . 
     It is worth noting that there are many ways to implement the operating parameters of the preferred cycle  306  and the invention does not rely on or need any particular method. For example, instead of requiring the user to enter the End Time and Bake Time, the user could have been asked to enter the Bake Start Time and End Time, effectively making the user, instead of the controller  220 , to perform the math to determine the Bake Start Time based on a given Cook Time. Also, the Cool_Cycle  304  does not have to automatically start at the completion of the Data_Input step  302 , which is based on the logic that the user will put the food in the cooking chamber  14  just before or shortly after initiating the preferred cycle. The preferred cycle  306  can require that the user input a start time for the Cool_Cycle  304  based on the logic that the user might initiate the preferred cycle well before the food is placed in the cooking chamber  14 . 
     In some cases, it may not even be necessary to have the user input the Bake Time. The Data_Input step  302  could prompt for information related to the food (type of food: cake, meat, etc.; physical characteristics: weight, frozen, thawed, etc.; cooking preference: well done, medium, rare) and determine the Cook Time therefrom. Many of the physical properties can be determined by sensors as it is well know in the art to do so. 
     It is also not even necessary to use times of the day in setting the operation parameters. Absolute times can be used in combination with a reference time, say, for example, the End Time is 8 hours from the initiation of the preferred cycle  300 . 
     Since there are many ways to implement the parameters for the preferred cycle  300 , the exact method is not germane to the invention. What is relevant to the invention is that the parameters provided enable the preferred cycle to know when to start and stop each of the cycles used: Cool_cycle  304 , Bake_Cycle  306 , Warm_Cycle  308 , and, if used, the optional Cool_Cycle  310 . 
     Returning now to the Cool_Cycle  304 ,  FIG. 14  illustrates the sub-steps and cycles for the Cool_Cycle  304 . The Cool_Cycle  304  begins at step  330  by checking the initial temperature of the cooking chamber  14  to determine if the cooking chamber  14  temperature (CCT) is less than a initiation temperature threshold (ITT), which is a temperature sufficiently low enough to begin operation of the modular refrigeration unit  20  without damaging the various components of the modular refrigeration unit  20  or substantially negatively impacting its operating performance. Upon confirming that the CCT is below the ITT, the modular refrigeration unit  20  is checked at step  332  to make sure that it is functioning properly, preferably by monitoring the CCT to determine if it drops below a threshold cooling temperature (TCT) for at least a predetermined time period, with both the TCT and the time period preferably set by the controller. After it is determined that the modular refrigeration unit  20  is working properly, the Cool_Cycle  304  advances to a Cooling_Cycle  334  that maintains the CCT at a temperature (Warm Temp.) sufficient to keep the food placed in the cooking chamber  14  from spoiling. 
     Looking at the sub-steps and cycles for the Cool_Cycle  304  greater detail,  FIG. 15  illustrates the details of the initial temperature check step  330 , which first begins by setting a timer  340 . The timer  340  is then compared against a predetermined initial temperature Cutoff Time  342 , which is preferably set by the controller. If the Cutoff Time  342  is not exceeded, the CCT is compared against the ITT  344 . If the CCT is less than the ITT, the modular refrigeration unit  20  can be safely started without damage or undue performance degradation and the Cool_Cycle  304  then advances to the check of the refrigeration system step  332 . However, if the CTT exceeds the ITT, then the initial temperature check  330  continues to monitor the CCT until either the CCT drops below the ITT or the Cutoff Time  342  is exceeded. If the Cutoff Time  342  is exceeded, it is assumed that the heating element of the refrigerated is still turned on or some other factor is adversely affecting the temperature of the cooking chamber  14 , and the cycle is aborted at step  346 . 
     If the CCT is below the ITT  344  within the Cutoff Time  342 , then control is passed to the check refrigeration system  332 , which is shown in detail in FIG.  16 . Upon entry into the check of the refrigeration system step  332 , the modular refrigeration unit  20  is turned on at step  350  and a Timer  352  for the check refrigeration system step  332  is started. The Timer  352  is then compared against a predetermined Cool Down Time  354 , which is preferably a parameter set by the controller  220 . If the Cool Down Time  354  is not exceeded, the temperature of the cooking chamber  14  is compared against the threshold cooling temperature (TCT)  356 , which is preferably a parameter set by the controller  220  and indicative of a temperature that is sufficiently low enough to prevent the food in the cooking chamber  14  from spoiling. If the CCT is less than the TCT  356 , then it is assumed that the modular refrigeration unit  20  is functioning properly and the refrigerator is turned off at  358  and control is then returned to the Cooling_Cycle  334 . 
     However, if the CCT is not less than the TCT  356 , the check refrigeration system step  332  continues to monitor the CCT until either the CCT is less than the TCT  356  or the Cool Down Time  354  is exceeded. If the Cool Down Time  354  is exceeded, it is assumed that the modular refrigeration unit  20  is not functioning properly and the cycle is aborted at step  346 . 
     Upon the successful completion of the check refrigeration step  332 , control then passes to the Cooling_Cycle  334  shown in FIG.  17 . The Cooling_Cycle  334  monitors the CCT at step  360  and turns the modular refrigeration unit  20  off at  362  if the CCT is less than the TCT or turns the modular refrigeration unit  20  on at step  364  if the CCT is greater than the TCT. The cycling on/off of the modular refrigeration unit  20  is continued as long as the Current Time (time of day) does not exceed the Bake Start Time, which is tested at step  366 . If the Current Time does exceed the Bake Start Time, then the Cool_Cycle  304  is completed and control passes back to the Bake_Cycle  306 . 
     It is worthy of a brief comment to note that the check refrigeration system step  332  and the Cooling_Cycle  334  could easily be combined. Since the Cooling_Cycle  334  and the check refrigeration system step  332  compare the CCT against the TCT, the check of the refrigeration system at step  332  could be easily accomplished by performing the time monitoring function of the check refrigeration step  332  during the Cooling_Cycle  334 . It is also within the scope of the invention that the value of the TCT may not be the same for the refrigeration system check  332  and the Cooling_Cycle  334 . 
     Although not illustrated in  FIG. 17 , under certain circumstances it will be desirable for the Cooling_Cycle  334  to be terminated before the Bake Start Time to permit the CCT to rise naturally based on the ambient room temperature. The termination of the Cooling_Cycle  334  prior to the Bake Start Time will reduce the amount of time needed to preheat the cooking chamber to the Bake Temp as part of the Bake_Cycle  306 . If such an early termination of the Cooling_Cycle  334  is used, it is contemplated that the corresponding time period will be a controller  220  selected parameter but could be user defined. 
     Upon the successful completion of the Cooling_Cycle  304 , the Bake Cycle  306  illustrated in  FIG. 18  is initiated. It should be noted that the Bake_Cycle  306  is a generic Bake_Cycle and that any suitable Bake_Cycle can be used. The Bake_Cycle  306  begins by comparing the CCT against the Bake Temp at step  370  and turning on the heating element at  372  if the CCT is less than the Bake Temp or turning off the heating element at  374  if the CCT is greater than the Bake Temp. The cycling on/off of the heating element is continued as long as the Current Time does not exceed the End Time, which is tested at step  376 . If the Current Time does exceed the End Time, then the Bake_Cycle  304  is completed and control passes back to the Warm_Cycle  308  at  308 . 
     Referring to  FIG. 19 , the Warm_Cycle  308  maintains the CCT at a temperature (the Warm Temp) so that the cooked food is maintained at a temperature suitable for serving for a predetermined time (the Warm Time). The Warm_Cycle  306  begins by starting a timer  380 . The CCT is then compared against a Warm Temp at step  382  and the heating element is turned on at  384  if the CCT is less than the Warm Temp or turned off if the CCT is greater than the Warm Temp. The cycling on/off of the heating element is continued as long as the timer  380  does not exceed the Warm Time, which is tested at step  386 . If the Warm Time does exceed the time  380 , then the Warm_Cycle  304  is completed and control passes back to the optional Cool_Cycle  310 . 
     The Warm Temp and the Warm Time are preferably controller-selected parameters that are stored in the read-only memory of the controller  220 . It is within the scope of the invention for the user to set the Warm Temp and the Warm Time. The user can enter the Warm Temp and the Warm Time during the Data_Input step  302  of the preferred cycle  300 . If desirable, the Data_Input step  302  can even include an option for the user to set the Warm Temp and/or Warm Time or the controller  220  can set them. It is preferred that the Warm Temp and Warm Time parameters be limited in such a manner to prevent the cooked food from becoming dried out to the extent that it is not edible. 
     The Warm Time and Warm Temp are preferably selected to be suitable for most baked foods to simplify the process. However, it is within the scope of the invention for the Warm Time and Warm Temp to be variable and even food or environment dependent. For example, it is known to use moisture sensors in ovens that are controlled by the controller. If the rate or absolute amount of moisture is at a level indicative of the food drying out beyond an edible limit, the Warm Time can automatically terminate, resulting in a dynamic time. Also, the user can be prompted to enter the type of food during the Data_Input cycle, say for example, Cake, Casserole, Soufflé, etc., and a predetermined Warm Time and even a predetermined Warm Temp can be stored in the controller memory for each food type. The food type can even be used in combination with the moisture sensor if desired. 
     The function of the Warm_Cycle  308  is to maintain the cooked food at a temperature suitable for serving for a predetermined period of time. In that way, a user who does not make it home at the end of the Bake_Cycle  306  will still have cooked food that is immediately ready for serving upon their arrival. The Warm_Cycle  308  is a great convenience for the user and if for any reason the user is late, the food will still be maintained at a temperature suitable for serving for a predetermined period of time. 
     Since the Warm_Cycle  308  is thought to be a great convenience for the user, it is preferred that the Warm_Cycle  308  automatically start at the end of the Bake_Cycle  306 . However, it is within the scope of the invention for the Warm_Cycle to the selected by the user as part of the Data_Input step  302 . 
     One option for the Warm_Cycle  308  is that it can be terminated prior to the running of the Warm Time upon the opening of the oven door  58 , which would activate the oven door sensor coupled to the controller  220 . Under most circumstances, it is anticipated that the user will arrive home prior to the termination of the Bake_Cycle  306 . Thus, where the Warm_Cycle  308  is automatically initiated after the completion of the Bake_Cycle  306 , the opening of the oven door  58  by the user will indicate that the user is now present and the food is ready to be served, resulting in the termination of the Warm_Cycle  308 . The option of terminating the Warm_Cycle  308  in response to the opening of the oven door  58  can easily be implemented by checking the status of the oven door flag in the memory of the controller  220  before, during, or after the check of the warm time at step  388 . 
     In the circumstance where the user selects the Warm_Cycle  308  during the Data_Input step  302 , it is preferred that the opening of the of the door  58  not result in the termination of the Warm_Cycle  308  since it is presumed that the user selection of the Warm_Cycle  308  is indicative of the user&#39;s desire for the Warm_Cycle  308  to run its entire course. If the user selects the Warm_Cycle  308  and desires for it to be terminated prior to the expiration of the Warm Time, then the user can manually stop the cycle. 
     The optional Cool_Cycle  310  is substantially identical to the Cool_Cycle  304  and will not be described in detail. It is preferred that the optional Cool_Cycle  310  automatically initiate at the end of the Warm_Cycle  308 . However, unlike the Cool_Cycle  304 , it is preferred that the Cool_Cycle  310  will preferably run until manually terminated by the user since it is anticipated that the circumstances under which the Cool_Cycle  310  is initiated are when the user cannot arrive home a substantial amount of time after the end of the Bake_Cycle. 
     It is contemplated, however, that the optional Cool_Cycle  310  should not be permitted to run beyond a certain predetermined time, preferably 24 hours. Under such circumstances, the controller  220  can be programmed with a predetermined time for terminating the optional Cool_Cycle  310 . 
     Another option for terminating the optional Cool_Cycle  310  is the opening of the oven door  58  in a manner similar to the previously described termination of the Warm_Cycle  308 . If the oven door  58  is opened during a Cool_Cycle  310  that was automatically initiated by the controller  220 , then it is contemplated that the user has arrived home and is removing the food from the cooking chamber  14 , making it now appropriate to terminate the Cool_Cycle  310 . 
     As with the Warm_Cycle  308 , when the Cool_Cycle  310  is selected by the user during the Data_Input step  302 , it is assumed that the user desires to have the Cool_Cycle  310  terminate naturally and the opening of the oven door  58  will not serve to terminate the Cool_Cycle  310 . 
     The preferred Time_Bake_Cycle with warming and optional cooling according to the invention provides the user with a very convenient means for cooking food while away from home, the cooked food being ready to eat at the desired time, and with the cooked food being maintained at a temperature ready to eat if the user is late in arriving. The maintenance of the cooked food at a temperature suitable for serving upon removal from the cooking chamber  14  provides the user with a great deal of flexibility in their schedule. The optional Cool_Cycle  310  further enhances the flexibility of the user in that if for some unknown reason the user must arrive home at a time much later than ever contemplated the food will not be warmed until inedible. 
     From the above, it is apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.