Patent Publication Number: US-2021190326-A1

Title: Steam cooking appliance

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/603,361 filed on May 23, 2017 which claims the benefit of U.S. Provisional Application No. 62/341,816, filed May 26, 2016, These applications are incorporated herein by reference. 
    
    
     FIELD 
     The present invention relates generally to methods and apparatus for controlling a cooking appliance, and, more particularly, for generating steam and for regulating a temperature of air within an oven cavity of the cooking appliance during a steam cooking operation. 
     BACKGROUND 
     Cooking appliances can include structure for cooking items within an oven cavity via convection. Moreover, some cooking appliances can include structure for baking items within the oven cavity. Furthermore, some cooking appliances include structure for steam-cooking items within the oven cavity. It is desirable to have structure and methodology for controlling a cooking appliance during steam cooking, convection cooking, and/or baking operations in an efficient and effective manner. 
     SUMMARY 
     In accordance with a first aspect, a cooking appliance includes a cooking chamber that defines an oven cavity and a reservoir for holding water that is accessible from within the oven cavity. The cooking appliance further includes a convection heating system, a reservoir heating system, and a control system. The convection heating system includes a convection heating element and a fan for guiding air across the convection heating element. The reservoir heating system includes at least one reservoir heating element. The control system is configured to control the convection heating system and the reservoir heating system to perform a steam cooking operation in response to a user steam-cooking input. 
     In accordance with a second aspect, a cooking appliance includes a cooking chamber that defines an oven cavity and a reservoir for holding water. The cooking appliance further includes a convection heating system, a reservoir heating system, and a shroud. The convection heating system includes a convection heating element and a fan for guiding air across the convection heating element. The reservoir heating system is configured to heat water in the reservoir in order to generate steam. The shroud at least partially covers the reservoir and includes an opening and a door for providing selective access to the reservoir through the opening. 
     In accordance with a third aspect, a method of operating a cooking appliance includes a step of performing a steam cooking operation. The steam cooking operation includes operating a convection heating system to regulate the temperature of air within an oven cavity of the appliance. The steam cooking operation further includes operating a reservoir heating system to heat a reservoir accessible from within the oven cavity and generate steam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other aspects will become apparent to those skilled in the art to which the present examples relate upon reading the following description with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic front perspective view of an example cooking appliance; 
         FIG. 2  is a schematic cross-sectional view of the example cooking appliance taken along plane P 2  in  FIG. 1 , with the door in a closed position; 
         FIG. 3  is a schematic cross-sectional view of the example cooking appliance taken along plane P 3  in  FIG. 1 , with the door in the closed position; 
         FIG. 4  is a perspective view of a shroud to be provided within an oven cavity of the example cooking appliance; and 
         FIG. 5  is a flow chart illustrating a method of operating the example cooking appliance. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation. In the drawings, certain features may be shown in somewhat schematic form. 
     It is to be noted that the term “energized” as used herein when describing a heating system or, more specifically, a heating element of the heating system, refers to a state in which chemical or electrical energy (e.g., combustible fuel, current, etc.) is being supplied to the heating element where that energy is used to generate (i.e. is converted to) thermal energy for heat transfer. For example, an electric-resistance heating element of a heating system is energized when current is being passed through that heating element to generate heat. The term “energized” does not refer to a state in which the heating element may be dissipating or radiating heat but is not being supplied with energy. For example, the resistance heating element described above would not be in an energized state when no electrical current is flowing to the element, even though the element may continue to dissipate or radiate residual heat while there is no current. 
     An example cooking appliance  10  is shown in  FIGS. 1-3 . The appliance  10  includes a housing  12  that supports a cooking chamber  14 . The cooking chamber  14  has a bottom wall  20 , a top wall  22 , a pair of opposing side walls  24 ,  26 , and a rear wall  28  that collectively define an oven cavity  32 . The cooking appliance  10  further includes a door  34  that can provide selective access to the oven cavity  32  through an opening  36  defined at the front of the cooking chamber  14 . 
     The cooking appliance  10  includes a convection heating system  40  for heating air within the oven cavity  32  via convection. As discussed further below, the convection heating system  40  can be controlled to perform a steam cooking operation or a convection cooking operation. The convection heating system  40  can include one or more convection heating elements and one or more fans associated with the convection heating element(s) for guiding air across the convection heating element(s). For instance, in the present example the convection heating system  40  includes one convection heating element  42  and one fan  44  associated with the convection heating element  42  for guiding air across the convection heating element  42 . However, in other examples, the convection heating system  40  may have one convection heating element  42  associated with multiple fans  44 , multiple convection heating elements  42  associated with the same fan  44 , and/or multiple convection heating elements  42  that are each associated with one or more different fans  44 . The convection heating element  42  can be an electric-resistance element (e.g., coil) that generates heat via an electric current. Alternatively, the convection heating element  42  can be some other element (e.g., an induction coil or gas burner assembly) that can be energized to produce heat for transfer to the oven cavity air via convection. The fan  44  may be located downstream from the convection heating element  42  to pull (i.e., suck) air past the convection heating element  42 , or the fan  44  may be located upstream from the convection heating element  42  to push (i.e., blow) air past the convection heating element  42 . 
     The convection heating system  40  may be located within the oven cavity  32  or it may be located outside of the cooking chamber  14  and fluidly coupled with the oven cavity  32  via one or more air passageways. In some examples, the cooking chamber  14  may form part of the convection heating system  40 . In the present example, the convection heating system  40  has a housing  46  attached to the rear wall  28  of the cooking chamber  14 . The housing  46  houses the convection heating element  42  and fan  44 . The convection heating system  40  further includes a cover  48  that is attached to the rear wall  28  and covers an opening  50  in the rear wall  28 . As the fan  44  is operated, air is drawn from the oven cavity  32  into the housing  46  via one or more inlets  52  in the rear wall  28 . The air is then guided past the convection heating element  42  and blown through one or more outlets  54  in the cover  48  back into the oven cavity  32 . However, the convection heating system  40  may have a variety of configurations for guiding air past the convection heating element  42 . 
     The cooking appliance  10  further includes a reservoir  56  for holding water  58  that can be heated to generate steam for dispersal throughout the oven cavity  32 . The reservoir  56  is accessible from within the oven cavity  32  and is preferably sized to hold a maximum of about 12 cups of water, though other volumes are possible. In some examples, the reservoir  56  is disposed at a base of the cooking chamber  14  and, in particular, at least partially forms the base of the cooking chamber  14 . For instance, in the illustrated embodiment the reservoir  56  is formed at the base of the cooking chamber  14  as a recessed embossment in the bottom wall  20  of the cooking chamber  14 . In particular, the reservoir  56  comprises a sump of the cooking chamber  14 . However, the reservoir  56  may be disposed at other locations and/or may form other portions of the cooking chamber  14 . Moreover, the reservoir  56  may be a separate structure (e.g., a pan or a vessel) that is provided within the cooking chamber  14 . 
     For instance, in some examples the reservoir  56  may be a pan that rests on a rack within the cooking chamber  14 . Alternatively, the pan may hang from an underside of the rack using for example, one or more brackets, such that the pan is suspended above the bottom wall  20  of the cooking chamber  14 . In such examples, the rack can be a wire rack and the pan can be located relatively close to the rack such that steam from the pan will disperse through openings formed by the wire(s) of the rack and contact any food items or cooking vessels resting on top of the rack. The reservoir  56  may be any structure that holds water for heating to generate steam. 
     The cooking appliance  10  further includes a reservoir heating system  60  configured to heat the reservoir  56  that, as discussed further below, can be controlled to perform a steam cooking operation or a baking operation. The reservoir heating system  60  can include one or more heating elements such as, for example, a first heating element  62  and a second heating element  64 , that are located exterior of the oven cavity  32  and reservoir  56  below the bottom wall  20  of the cooking chamber  14 . However, the reservoir heating system  60  may include any number of heating elements in other examples. Moreover, one or more heating elements may be provided in other locations such as, for example, within the actual reservoir  56  or within some other portion of the oven cavity  32 . Furthermore, one or more heating elements may form a portion of the reservoir  56  itself. Each heating element can be an electric-resistance element (e.g., coil) that generates heat via an electric current, or some other element (e.g., an induction coil or gas burner assembly) that can be energized to produce heat for transfer to the water  58  within the reservoir  56  or other portions of the cooking chamber  14  (e.g., the air within the oven cavity  32 ). 
     When the reservoir heating system  60  includes more than one heating element, the reservoir heating system  60  can be configured to provide different amounts of power for each heating element. For example, in the present embodiment the first and second heating elements  62 ,  64  are heating coils that are concentrically arranged such that the first heating element  62  is surrounded by the second heating element  64 , as shown in  FIG. 3 . The reservoir heating system  60  can be configured to provide a first amount of power to the first heating element  62  when the first heating element  62  is energized and a second amount of power to the second heating element  64  when the second heating element  64  is energized. The second amount of power to the second heating element  64  may be greater than the first amount of power to the first heating element  62 , or vice versa. Alternatively, the amounts of power for the heating element  62 ,  64  may be substantially similar or equal. 
     In some examples, the reservoir  56  may be an open reservoir provided at a base of the cooking chamber  14  such that the reservoir  56  is open to the oven cavity  32  and the surface of the water  58  in the reservoir  56  is exposed to the oven cavity  32 . Moreover, the cooking appliance  10  can include a shroud  66  (shown in  FIG. 4 ) that can be arranged within the oven cavity  32  to at least partially cover the reservoir  56  and the exposed surface of the water  58 . The shroud  66  includes a panel  68  that will act as a barrier between the reservoir  56  and the oven cavity  32  to prevent food particles from falling into the reservoir  56 . In the present example, the panel  68  can be suspended above the reservoir  56  on rails provided along the walls of the cooking chamber  14 . In other examples though, the panel  68  can be suspended above the reservoir  56  using, for example, legs that sits on a floor of the reservoir  56  and hold the panel  68  above the surface of the water  58 . A variety of different structure may be used to suspend the panel  68  above the reservoir  56 . 
     In some examples, the shroud  66  includes a plurality of apertures  72  in the panel  68  for distributing steam about the oven cavity  32 . As the water  58  in the reservoir  56  is heated and vaporized to steam, the steam will rise through the plurality of apertures  72  and permeate the oven cavity  32  above the panel  68 . Some steam also may rise around one or more edges of the panel  68 . 
     In some embodiments, the shroud  66  has an opening  76  in the panel  68 . The opening  76  is preferably sized and located such that water can be poured through the opening  76  into the reservoir  56 . In such embodiments, the shroud  66  can have a door  78  that is movably coupled to the panel  68  for providing selective access to the reservoir  56  through the opening  76 . For example, the door  78  may be slidably coupled to the panel  68  or the door  78  may be pivotally coupled to the panel  68  with a hinge. In the present example, the door  78  is coupled to the panel  68  with a hinge assembly  80  that permits the door  78  to rotate between open and closed positions about a horizontal axis X that extends substantially parallel to the rear wall  28 . The door  78  has first and second major surfaces  82 ,  84  that face opposite directions. In the closed position, the door  78  will cover the opening  76  and be arranged such that the first and second major surfaces  82 ,  84  are substantially horizontal with the first major surface  82  facing upward and the second major surface  84  facing downward toward the reservoir  56 . From the closed position, the door  78  can be rotated about the horizontal axis X in a direction away from the rear wall  28  until the door  78  reaches its open position, as shown in  FIG. 4 . In the open position, the door  78  will be inclined such that the second major surface  84  faces upward and has a downslope toward the opening  76  and rear wall  28 . With this arrangement, a consumer can fill the reservoir  56  from the front of the cooking appliance  10  by pouring water onto the second major surface  84 , which will guide water downward through the opening  76  into the reservoir  56 . In some examples, the door  78  can have a pair of guide walls  88  that extend from the second major surface  84  to help guide the water as it flows down the second major surface  84 . 
     Turning now to  FIG. 5 , an example method  100  of operating the cooking appliance  10  will now be described. The method  100  includes a step of performing a steam cooking operation  102 , which can include one or more sub-steps such as a pre-heating step  104 , a temperature regulating step  106 , and a reservoir heating step  108 . The pre-heating step  104  comprises increasing the temperature of the air within the oven cavity  32  from a first temperature (e.g., room temperature) to a second temperature (e.g., a predetermined cooking temperature). The temperature regulating step  106  comprises regulating (e.g., adjusting and/or maintaining) the temperature of the air within the oven cavity  32 . For instance, the temperature regulating step  106  can include maintaining the second temperature achieved during the pre-heating step  104  for a definite or indefinite period of time. In addition or alternatively, the temperature regulating step  106  can include adjusting (e.g., increasing or decreasing) the temperature of the air within the oven cavity  32  from the second temperature to a third temperature that is different from (e.g., greater than or less than) the second temperature. The reservoir heating step  108  comprises heating the reservoir  56  to a temperature equal to or greater than the boiling point of water such that water (if present in the reservoir  56 ) is converted to steam. The steam cooking operation  102  can comprise any one or more of the pre-heating step  104 , temperature regulating step  106 , and reservoir heating step  108 . 
     The temperature regulating step  106  is preferably initiated after completion of the pre-heating step  104 . The reservoir heating step  108  can be initiated before, during, or after either of the pre-heating step  104  and the temperature regulating step  106 . Water can be added to the reservoir  56  either before or during the reservoir heating step  108 . In a preferred embodiment, water will be added to the reservoir  56  prior to the steam cooking operation  102  when the oven cavity  32  is at room temperature. The pre-heating step  104  will then be performed, followed by the temperature regulating step  106  upon completion of the pre-heating step  104 . The reservoir heating step  108  preferably will likewise be initiated after the pre-heating step  104 , thereby mitigating the amount of steam generated in oven cavity  32  during the pre-heating step  104 . By mitigating the amount of steam generated during the pre-heating step  104 , the potential for scalding to occur when a user opens the door  34  immediately after conclusion of the pre-heating step  104  can be reduced. 
     The pre-heating step  104 , temperature regulating step  106 , and reservoir heating step  108  can be performed by operating the convection system  40  and/or the reservoir heating system  60 . The convection heating system  40  typically provides more accurate control of air temperature than the reservoir heating system  60 . Accordingly, in a preferred embodiment, the pre-heating step  104  and temperature regulating step  106  will each be performed by operating the convection heating system  40  independently of the reservoir heating system  60  such that the convection heating system  40  will provide substantially 100% of the active control (relative to the reservoir heating system  60 ) for regulating (e.g., adjusting or maintaining) air temperature during the pre-heating step  104  and temperature regulating step  106 . In other words, the reservoir heating system  60  will not be operated (e.g., actively controlled) for the purposes of regulating air temperature, i.e. it will not be operated based on or in response to any measurement or sensing of the air temperature within the oven cavity  32  during the pre-heating step  104  and the temperature regulating step  106 . Rather, the air temperature within the oven cavity  32  will be regulated by operating one or more aspects of the convection heating system  40 . For example, during the pre-heating step  104  and temperature regulating step  106 , the air temperature within the oven cavity  32  can be regulated by energizing the convection heating element  42 , de-energizing the convection heating element  42 , maintaining the convection heating element  42  in an energized or de-energized state, turning on the fan  44 , turning off the fan  44 , maintaining the fan  44  in an on or off state, or some combination thereof. 
     The reservoir heating system  60  typically is more efficient at heating the reservoir  56  than the convection heating system  40 . Accordingly, in the preferred embodiment, the reservoir heating step  108  will be performed by operating the reservoir heating system  60  to heat the reservoir  56 . If the reservoir heating system  60  has multiple heating elements, the reservoir heating step  108  can include energizing one or more of the heating elements. For example, the reservoir heating step  108  can include energizing only the first heating element  62 , only the second heating element  64 , or both the first and second heating elements  62 ,  64 , Preferably, only one of the heating elements  62 ,  64  will be energized in order to conserve energy and prevent rapid water loss in the reservoir  56 . In particular, the heating element that receives the lower amount of power (of the two elements) will be energized while the heating element that receives the higher amount of power will not be energized. However, any number of heating elements can be energized in the reservoir heating step  108 . 
     As discussed above, the pre-heating step  104  and temperature regulating step  106  are preferably performed by operating the convection heating system  40  independently of the reservoir heating system  60  such that the convection heating system  40  provides substantially 100% of the active control of the air temperature in the oven cavity  32  during the pre-heating step  104  and the temperature regulating step  106 . Meanwhile, the reservoir heating step  108  is preferably performed by operating the reservoir heating system  60  to heat the reservoir  56 , solely for the purpose of generating steam. However, if the reservoir heating system  60  is operated during the pre-heating step  104  and/or temperature regulating step  106 , the reservoir heating system  60  may have some influence on the air temperature within the oven cavity  52  while it heats the reservoir  56 . To the extent that this is the case, however, it is still only the convection heating system  60  that will be actively operated to regulate the air temperature in the oven cavity  32  in response to temperature changes or fluctuations therein. More specifically, the duration and degree of energization of the reservoir heating system  60  will be determined based on one or more factors other than air temperature such as, e.g., a predetermined time interval, a detected steam level (% R.H.), sensing (or not) of a boil-dry condition in the reservoir  56 , a user command, a temperature of the reservoir  56 , a temperature of a heating element for the reservoir heating system  60 , or some combination thereof. As such, the reservoir heating system  60  will not be actively operated to achieve or maintain a particular air temperature. Accordingly, while the reservoir heating system  60  may be operated in a manner that affects air temperature, the reservoir heating system  60  will not be operated (e.g., actively controlled) or relied upon for the purposes of regulating air temperature. The result is an efficient system where the convection heating system  40  is operated to regulate air temperature while the reservoir heating system  60  is operated to heat the reservoir  56  and generate steam during a steam cooking operation  102 . 
     Although it is preferable to have the convection heating system  40  provide substantially 100% of the active control of the air temperature in the oven cavity  32  during the pre-heating step  104  and the temperature regulating step  106 , the convection heating system  40  in some embodiments may not be powerful enough to maintain or achieve certain desired temperatures (e.g., 300° F. or higher). For instance, in embodiments wherein the convection heating system  40  comprises an electric heating element  42  in an otherwise gas oven (e.g., wherein the reservoir heating system  60  comprises a gas burner), industry regulations may require that the electric heating element  42  of the convection heating system  40  have a relatively low power to prevent accidental ignition of gas being supplied to the oven. Thus, in such embodiments the convection heating system  40  and the reservoir heating system  60  may both be operated to provide control of the air temperature in the oven cavity  32  during the pre-heating step  104  and/or the temperature regulating step  106 . 
     It should be noted that in embodiments wherein the reservoir heating system  60  is operated to help control air temperature in the oven cavity  32 , the presence of water  58  within the reservoir  56  could limit the ability of the reservoir heating system  60  to facilitate control of air temperatures above the boiling point of water. More specifically, if the reservoir  56  is located at the bottom of the oven cavity  32  between the oven cavity  32  and the heating element(s)  62 ,  64  of the reservoir heating system  60 , water  58  within the reservoir  56  can act as an insulator that limits the ability of the reservoir heating system  60  to heat the air within the oven cavity  32  above the boiling point of water. In particular, since the maximum attainable temperature of water/steam is its boiling point (e.g., 212° F. at standard pressure), the highest temperature to which the reservoir heating system  60  would be able to heat the reservoir  56  (and the air above the reservoir  56 ) while the reservoir  56  contains water  58  is the water&#39;s boiling point. Thus, the reservoir heating system  60  would not be able to facilitate the maintenance or attainment of air temperatures in the oven cavity  32  above the boiling point of water. Indeed, even if the air within the oven cavity  32  were supplemented with heat from the convection heating system  40  in order to achieve a temperature above the boiling point of water, the reservoir  56  would act as a heat sink that tends to cool the air within the oven cavity  32  and can counteract the heating effect of the convection heating system  40 . Accordingly, in embodiments wherein the reservoir heating system  60  is operated to help control air temperature in the oven cavity  32 , it is preferable that 1) water is not present within the reservoir  56  while controlling air temperature with the reservoir heating system  60 ; and/or  2 ) water is provided so that it is not a barrier between the heating element(s)  62 ,  64  of the reservoir heating system  60  and the air within the oven cavity  32 . For example, the water can be provided in a pan that rests on a rack within the oven cavity, or that is suspended beneath a rack on which food being cooked rests, as described above. 
     In some examples, the method  100  also includes the step  112  of performing a baking operation. In contrast to the steam cooking operation  102 , the baking operation  112  can regulate the temperature of the air within the oven cavity  32  by operating the reservoir heating system  60  independently of the convection heating system  40 . In other words, the convection heating system  40  is not necessarily solely relied upon (e.g., controlled) for the purposes of regulating air temperature during the baking operation  112 . Rather, the reservoir heating system  60  can provide up to substantially 100% of the active control (relative to the convection heating system  40 ) for regulating air temperature. Indeed, in some examples the convection heating system  40  will not be operated (e.g., energized) to regulate air temperature or for any other purpose during the baking operation  112 . 
     During the baking operation  112 , one or more of the heating elements of the reservoir heating system  60  can be operated in order to adjust or maintain the oven air temperature. For example, the air temperature can be adjusted or maintained by energizing either or both of the first and second heating elements  62 ,  64 , de-energizing either or both of the first and second heating elements  62 ,  64 , maintaining either or both of the first and second heating elements  62 ,  64  in an energized or de-energized state, or some combination thereof. In some examples, one of the first and second heating elements  62 ,  64  can be operated (e.g., energized) to generate steam during the steam cooking operation  102 , while the other of the heating elements  62 ,  64  is operated (e.g., energized) during the baking operation  102  to regulate the oven air temperature. In particular, the heating element that receives the higher amount of power can be operated during the baking operation  102  to regulate oven air temperature. 
     As noted above, the presence of water  58  within the reservoir  56  could limit the ability of the reservoir heating system  60  to facilitate control of air temperatures in the oven cavity  32  above the boiling point of water. Accordingly, during the baking operation  112 , it is preferable that 1) water is not present within the reservoir  56 ; and/or  2 ) the water (if present to facilitate steam baking) is provided within the oven cavity  32  such that it is not a barrier between the heating element(s)  62 ,  64  of the reservoir heating system  60  and the air within the oven cavity  32 . However, it is to be appreciated that the reservoir  56  may nonetheless contain some amount of water during the baking operation  112 , particularly at the beginning of the baking operation  112  before it is boiled substantially dry. 
     In further examples, the method  100  also can include the step of performing a convection operation  114 . Preferably, the convection operation  114  can regulate the temperature of the air within the oven cavity  32  by operating the convection heating system  40  without operating the reservoir heating system  60 . In particular, the reservoir heating system  60  will not necessarily be energized during the convection operation  114 . As such, the convection heating system  40  will provide up to substantially 100% of the active control and thermal energy (relative to the reservoir heating system  60 ) for regulating air temperature in the convection operation  114 . However, in embodiments wherein the convection heating system  40  does not have sufficient power to provide 100% of control for regulating air temperature during the convection operation  114 , the reservoir heating system  60  may be operated in combination with the convection heating system  40  to regulate air temperature during the convection operation  114 . 
     The method  100  can include steps for performing the steam cooking operation  102 , the baking operation  112 , the convection operation  114 , or any combination thereof. In some embodiments, the cooking appliance  10  can include a control system  120  (shown in  FIG. 2 ) configured to automatically perform any of the method steps described above. The control system  120  includes a controller  122  that can be connected to the convection heating system  40  and/or the reservoir heating system  60 . Moreover, the control system  120  can include a user interface  124  that is connected to the controller  122  and can permit a user to selectively provide command signals to the controller  122 . Furthermore, the control system  120  can include one or more sensors connected to the controller  122  that can be used to detect various parameters of the cooking appliance  10  and send signals to the controller  122  that are indicative of the detected parameters. For example, the control system  120  can include a temperature sensor  126  that is configured to detect a temperature of the air within the oven cavity  32  or a steam sensor  128  that is configured to detect an amount of steam (e.g. % R.H.) within the oven cavity  32 . The controller  122  can be any kind of microprocessor unit that is configured to receive one or more inputs (e.g., signals) and to control the convection heating system  40  and/or the reservoir heating system  60  based on the received input(s). 
     The control system  120  can be configured to control the convection heating system  40  and the reservoir heating system  60  to automatically perform the steam cooking operation  102  described above. For example, in response to a user input (e.g., a steam-cooking start command entered using the user interface  124 ), the controller  122  can perform the pre-heating step  104  and the temperature regulating step  106  by controlling one or more aspects of the convection heating system  40  in order to adjust and/or maintain the temperature of the air within the oven cavity  32 . In particular, the controller  122  can adjust or maintain the temperature by energizing the convection heating element  42 , de-energizing the convection heating element  42 , maintaining the convection heating element  42  in an energized or de-energized state, turning on the fan  44 , turning off the fan  44 , maintaining the fan  44  in an on or off state, or some combination thereof. In embodiments wherein the convection heating system  40  does not have sufficient power to provide 100% of the control for regulating air temperature during the pre-heating step  104  and/or the temperature regulating step  106 , the controller  122  can control the reservoir heating system  60  in combination with the convection heating system  40  to perform the pre-heating step  104  and/or the temperature regulating step  106 . In particular, the controller  122  can adjust or maintain air temperature by energizing one or both the first and second heating elements  62 ,  64 , de-energizing one or both the first and second heating elements  62 ,  64 , or maintaining one or both the first and second heating elements  62 ,  64  in an energized or de-energized state. 
     During the steam cooking operation  102 , the control system  120  also can perform the reservoir heating step  108  by automatically energizing the reservoir heating system  60  to heat the reservoir  56  and the water  58  to generate steam within the oven cavity  32 . If the reservoir heating system  60  has multiple heating elements, the controller  122  can be configured to automatically energize one or more of the heating elements. For example, the controller  122  can energize only the first heating element  62 , only the second heating element  64 , or both the first and second heating elements  62 ,  64 . Preferably, only one of the heating elements  62 ,  64  will be energized in order to conserve energy and prevent rapid water loss in the reservoir  56 . In particular, the heating element that receives the lower amount of power will be energized while the heating element that receives the higher amount of power will not be energized. However, any number of heating elements can be energized by the controller  122 . 
     During the steam cooking operation  102 , the control system  120  can be configured to perform the pre-heating step  104  and the temperature regulating step  106  sequentially. Moreover, the control system  120  can be configured to initiate the reservoir heating step  108  before, during, or after the pre-heating step  104  and/or temperature regulating step  106 . For instance, in response to receiving the steam cooking start signal, the controller  122  can automatically perform the pre-heating step  104  to adjust (e.g., raise) the temperature of the air within the oven cavity  32  from a first temperature (e.g., room temperature) to a second temperature (e.g., a predetermined cooking temperature) using the convection heating system  40 . Preferably, this is performed while the reservoir heating system  60  is not energized. Following the pre-heating step  104 , the temperature sensor  124  will send a preheat-complete signal to the controller  122  indicating that the air within the oven cavity  32  has reached the second temperature. In response to the preheat-complete signal, the controller  122  can be configured to perform the temperature regulating step  106  to maintain the oven air temperature at the second temperature for an indefinite or a predetermined amount of time or to immediately adjust the temperature to another level. Moreover, in response to the preheat-complete signal, the controller  122  can automatically perform the reservoir heating step  108  by energizing the reservoir heating system  60  in order to heat the reservoir  56  and the water  58  within. As such, the reservoir heating system  60  will not be energized until the pre-heating step  104  is complete, thereby mitigating the amount of steam generated in oven cavity  32  during preheat. 
     During the steam cooking operation  102 , the controller  122  can be configured to regulate the temperature of the air within the oven cavity  32  by controlling the convection heating system  40  independently of the reservoir heating system  60  such that the convection heating system  40  will provide up to substantially 100% of the active control (relative to the reservoir heating system  60 ) for regulating air temperature. Preferably, the control system  120  will not control the reservoir heating system  60  during the steam cooking operation  102  to regulate (e.g., actively maintain or adjust) air temperature within the cooking cavity, even though the control system  120  may control the reservoir heating system  60  to heat the reservoir  56  in a manner that incidentally affects air temperature. To the extent of any such incidental effect, the control system  120  will control the convection heating system  40  to compensate. 
     In some examples, the control system  120  also can be configured to control the reservoir heating system  60  to automatically perform the separate baking operation  112  described above. For example, in response to a user input (e.g., a baking start command entered using the user interface  124 ), the controller  122  can be configured to automatically regulate the temperature of the air within the oven cavity  32  by controlling the reservoir heating system  60  independently of the convection heating system  40  such that the control system  120  does not control the convection heating system  40  to regulate the temperature of the air. As such, the reservoir heating system  60  will provide up to substantially 100% of the active control (relative to the convection heating system  40 ) for regulating air temperature during such a baking operation  112 . Indeed, in some examples the controller  122  will not control (e.g., energize) the convection heating system  40  for any purpose during the baking operation  112 . 
     During the baking operation  112 , the controller  122  can be configured to control one or more of the heating elements  62 ,  64  of the reservoir heating system  60  in order to adjust or maintain the oven air temperature. For example, the controller  122  can adjust or maintain the air temperature by energizing either or both of the first and second heating elements  62 ,  64 , de-energizing either or both of the first and second heating elements  62 ,  64 , maintaining either both of the first and second heating elements  62 ,  64  in an energized or de-energized state, or some combination thereof. In some examples, the controller  122  can be configured to energize only one of the first and second heating elements  62 ,  64  during the steam cooking operation  102 , while controlling the other the first and second heating elements  62 ,  64  during the baking operation  112  to regulate the oven air temperature. In particular, the heating element that receives the higher amount of power can be energized in the baking operation  112  to regulate oven air temperature. 
     In further examples, the control system  120  also can be configured to control the convection heating system  40  to automatically perform the convection operation  114  described above. For example, in response to a user input (e.g., a convection-cooking start command entered using the user interface  124 ), the controller  122  can be configured to automatically regulate the temperature of the air within the oven cavity  32  by preferably controlling the convection heating system  40  without controlling the reservoir heating system  60 . The reservoir heating system  60  need not be energized during the convection operation. As such, the convection heating system  40  will provide up to substantially 100% of the active control (relative to the reservoir heating system  60 ) for regulating air temperature in the convection operation  114 . However, in embodiments wherein the convection heating system  40  does not have sufficient power to provide 100% of control for regulating air temperature during the convection operation  114 , the controller  122  can control the reservoir heating system  60  in combination with the convection heating system  40  to regulate air temperature in the convection operation  114 . In particular, the controller  122  can adjust or maintain air temperature by energizing one or both the first and second heating elements  62 ,  64 , de-energizing one or both the first and second heating elements  62 ,  64 , or maintaining one or both the first and second heating elements  62 ,  64  in an energized or de-energized state. 
     The invention has been described with reference to example embodiments described above. Modifications and alterations will occur to others upon a reading and understanding of this specification. Example embodiments incorporating one or more aspects described above are intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.