Patent Publication Number: US-2018028012-A1

Title: Slow cooker appliance and method of operation

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to cooking appliances, and more particularly to slow cooker appliances. 
     BACKGROUND OF THE INVENTION 
     Slow cookers or slow cooking appliances generally include a heating element that is configured to slowing heat the contents (e.g., food items) within a ceramic pot. A lid may be positioned over the pot to trap heat and/or moisture, allowing food items within the ceramic pot to be slowly heated without becoming undesirably dry. Food items being heated within the pot often require little to no attention from a user. As a result, much of the preparation required may be performed well in advance of the time at which a user wishes to eat a given food item. 
     Although slow cooking appliances may reduce the amount of active time and effort that a user must expend, limitations still exist. For instance, although certain preparations may be done in advance of cooking or heating, most food items cannot be added until immediately before cooking operations begin. If added too soon, some food items, such as those that normally require refrigeration, may otherwise spoil. Moreover, once cooked, many food items will need to be quickly removed from the pot. From the pot, food items may be stored within a separate container and/or within a refrigerator. If left within the appliance or pot, some food items may overheat or spoil. Removal and/or storage of food items may be difficult, messy, and/or cumbersome. Although some pots are removable from the slow cooking appliance, a user&#39;s refrigerator may be unable to accommodate the pot. For instance, the pot may be too large, or the refrigerator may be otherwise full. 
     Accordingly, it would be advantageous to provide a slow cooker appliance that addressed the above concerns. In particular, it would be advantageous to provide a slow cooker appliance that included one or more features enabling food to be refrigerated or otherwise stored within the slow cooking appliance before and/or after cooking operations take place. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one aspect of the present disclosure, a slow cooker appliance is provided. The slow cooker appliance may include a casing, a heating element, a cooking utensil, and a sealed refrigeration system for circulating a refrigerant. The casing may define a utensil chamber. The heating element may be mounted within the casing proximate to the utensil chamber. The cooking utensil may be received within the utensil chamber. The sealed refrigeration system may include an evaporator and a compressor. The evaporator may be in conductive thermal engagement with the cooking utensil. The compressor may be positioned downstream from the evaporator to compress refrigerant from the evaporator. 
     In another aspect of the present disclosure, a method of operating a slow cooker appliance is provided. The slow cooker appliance may include a casing defining a utensil chamber, a heating element, a cooking utensil received within the utensil chamber, an evaporator in conductive thermal engagement with the cooking utensil, and a compressor positioned downstream from the evaporator. The method may include determining a heating condition for the cooking utensil, and activating the heating element to transmit heat to the utensil chamber in response to the determined heating condition. The method may further include determining a cooling condition for the cooking utensil, and activating the compressor to circulate refrigerant within the sealed refrigeration system in response to the determined cooling condition. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures. 
         FIG. 1  provides a perspective view of a slow cooker appliance according to an exemplary embodiment of the present disclosure. 
         FIG. 2  provides a cross-sectional view of a slow cooker appliance according to an exemplary embodiment of the present disclosure. 
         FIG. 3  provides a top perspective view of an evaporator for a slow cooker appliance according to an exemplary embodiment of the present disclosure. 
         FIG. 4  provides a cross-sectional view of the exemplary evaporator of  FIG. 3  along the line  4 - 4 . 
         FIG. 5  provides a top perspective view of an evaporator for a slow cooker appliance according to an exemplary embodiment of the present disclosure. 
         FIG. 6  provides a cross-sectional view of the exemplary evaporator of  FIG. 5  along the line  6 - 6 . 
         FIG. 7  provides a flow chart of a method of slow cooker operation according to an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Generally, a slow cooker appliance is provided in exemplary embodiments of the present disclosure. The slow cooker appliance may include a casing that houses an electric heating element. The casing may be shaped to receive a cooking utensil, such as a ceramic or aluminum pot. The cooking utensil is generally configured to hold or contain food items to be cooked. An evaporator may be placed beneath the cooking utensil as part of a sealed cooling system. During use, the electric heating element and sealed cooling system may be alternately or alternatively activated to respectively heat and cool food items within the cooking utensil. 
     Turning now to the figures,  FIGS. 1 and 2  provide an exemplary embodiment of a slow cooker appliance  10 . As illustrated, slow cooker appliance  10  generally includes a casing  12  that defines a utensil chamber  14 . A cooking utensil  16 , such as a pot, may be positioned or received at least partially within casing  12 , e.g., at utensil chamber  14 . A heating element  18  and sealed cooling system  20  may be provided to selectively heat or cool cooking utensil  16 . A lid  22  may also be provided. During use, lid  22  may be selectively placed on or over cooking utensil  16  to restrict air and/or heat passage therethrough. As will be understood, certain items, such as food, can be placed into cooking utensil  16 . When cooking utensil  16  is disposed within casing  12 , appliance  10  may heat and/or cool the provided food items, as will be described below. 
     As shown, casing  12  includes one or more unique walls  24 ,  26 ,  28 . The walls  24 ,  26 ,  28  may define utensil chamber  14 . For instance, an inner wall  26  may define at least a portion of utensil chamber  14 , e.g., in a vertical direction V defined by casing  12 . An outer wall  24  is disposed radially outward from utensil chamber  14  and inner wall  26  (i.e., outward in a radial direction R defined by casing  12 ). Inner wall  26  may be positioned radially between outer wall  24  and utensil chamber  14 . One or more of outer wall  24  or inner wall  26  may extend, e.g., substantially in the vertical direction V. In some embodiments, inner wall  26  at least partially defines utensil chamber  14  between a lower edge  30  and an upper edge  32 . An internal base wall  28  may extend across a bottom portion of utensil chamber  14 , defining utensil chamber  14 , e.g., as a lowermost vertical extreme. Bottom wall  28  may extend in the radial direction R and/or connect lower edge  30  of the inner wall  26 . Upper edge  32  of inner wall  26  may be positioned opposite of the lower edge  30  to define an opening  34 . As shown, opening  34  generally permits access to utensil chamber  14 . In certain embodiments, a top rim  36  extends radially outward from the upper edge  32 . Optionally, top rim  36  may join inner wall  26  to outer wall  24 . Additionally or alternatively, top rim  36  may support cooking utensil  16 , e.g., when cooking utensil  16  is received within utensil chamber  14 . 
     Between outer wall  24  and inner wall  26 , casing  12  may define an element chamber  38 . In some such embodiments, a heating element  18  may be mounted therein. For instance, heating element  18  may be mounted proximate to utensil chamber  14  to provide heat thereto. In certain embodiments, heating element  18  is mounted in fixed contact with inner wall  26 . Optionally, insulation (e.g., foam insulation) may be mounted within element chamber  38 . Additionally or alternatively, air may insulate the space between heating element  18  and outer wall  24 . Upon being mounted, heating element  18  may be radially spaced between inner wall  26  and outer wall  24 . Additionally or alternatively, heating element  18  may be disposed about utensil chamber  14 , e.g., such that heating element  18  substantially surrounds utensil chamber  14 . In some embodiments, heating element  18  is shaped as a single ring (either partially or fully surrounding utensil chamber  14 ). In alternative embodiments, heating element  18  is shaped as a helical coil. However, other suitable shapes may also be provided in additional or alternative embodiments. 
     In the illustrated embodiments, heating element  18  is an electric resistive heating element  18 . Although a single coiled resistive heating element  18  is shown, multiple discrete heating elements  18  may be provided in alternative embodiments. As discussed in greater detail below, each heating element  18  may be operably connected (e.g., electrically coupled) to a user interface  40  and/or controller  42  configured to control one or more elements of appliance  10 . 
     In some embodiments, casing  12  defines an enclosed chamber  43  that houses all or some of sealed cooling system  20 . For instance, enclosed chamber  43  may be defined below internal base wall  28 . One or more vent apertures  44  may be defined through casing  12 , e.g., in fluid communication with enclosed chamber  43 , to permit air exchange between the ambient environment and enclosed chamber  43 . 
     As noted above, cooking utensil  16  may be received within utensil chamber  14 . Cooking utensil  16  generally defines a food cavity  46  to hold food within appliance  10 , e.g., during heating or cooling operations. Cooking utensil  16  may be formed from one or more suitable heat-resistant materials, such as aluminum, glass, ceramic, laminates, plastics, another metal, etc. In some embodiments, cooking utensil  16  is permanently mounted to casing  12 . In alternative embodiments, cooking utensil  16  removably rests on a portion of casing  12 . For instance, a radial band  48  of cooking utensil  16  may rest upon top rim  36 . In turn, cooking utensil  16  may be selectively removed, e.g., by lifting radial band  48  off of top rim  36  and drawing the remaining portion of cooking utensil  16  away from utensil chamber  14 . 
     A sealed cooling system  20  is provided to circulate a refrigerant fluid therein. As illustrated, exemplary embodiments of sealed cooling system  20  include a compressor  50 , a condenser  52 , a throttling device  54 , and an evaporator  56 . Evaporator  56  is generally provided in conductive thermal engagement with cooking utensil  16  (e.g., at a bottom portion of cooking utensil  16 ). Compressor  50  is generally positioned downstream evaporator  56  to compress refrigerant from evaporator  56 . 
     As is generally understood, various conduits may be utilized to flow or direct refrigerant between the various components of the sealed system  20 . The compressor  50 , condenser  52 , throttling device  54 , and evaporator  56  may each be placed in fluid communication such that refrigerant generally flows downstream from the compressor  50  to the rest of the system before returning to the compressor  50 . 
     During operation, the compressor  50  motivates the refrigerant through the sealed cooling system  20  and acts to compress the refrigerant through the compressor  50 , increasing pressure and temperature of the refrigerant such that the refrigerant becomes a superheated vapor. As a superheated vapor, the refrigerant then passes to the condenser  52 , which may be positioned directly downstream from the compressor  50 . Within the condenser  52 , the refrigerant is cooled as heat is drawn therefrom. The refrigerant subsequently exits the condenser  52  as a saturated liquid and/or high quality liquid vapor mixture. Optionally, a fan  58  may be provided adjacent to the compressor  50 , in fluid isolation from the refrigerant. During operation, fan  58  may force and/or direct air (e.g., through vent apertures  44 ) across condenser  52  and accelerate heat transfer between condenser  52  and the ambient environment. 
     From the condenser  52 , the saturated liquid and/or high quality liquid vapor mixture travels through the throttling device  54 , which is configured for regulating a flow rate of refrigerant therethrough. The throttling device  54  may generally expand the refrigerant, lowering the refrigerant&#39;s pressure and temperature. As a result, a cooled form of the refrigerant passes to the evaporator  56 . While passing through the evaporator  56 , the cooled refrigerant absorbs heat transferred to evaporator  56  from cooking utensil  16  and/or any items therein. Refrigerant may exit the evaporator  56  in a gasified vapor form before passing back to the compressor  50 . Additional elements, such as an accumulator (not pictured) may be provided in some embodiments and may be configured to maintain gasification of the fluid flow as the refrigerant passes from the evaporator  56  to the compressor  50 . Upon the refrigerant reaching the compressor  50 , the cycle repeats. 
     A user interface  40  and/or controller  42  are included in exemplary appliance embodiments. User interface  40  generally includes one or more interface elements, such as a button, switch, touch screen, or display to receive user inputs and/or provide information regarding the slow cooker appliance  10 . In optional embodiments, user interface  40  is mounted to casing  12 , e.g., at outer wall  24 . Controller  42  may be operably connected to user interface  40  and configured to control or regulate the heating element  18  and/or sealed cooling system  20 . 
     Controller  42  may include memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of the slow cooker appliance  10 . The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory can be a separate component from the processor or can be included onboard within the processor. Alternatively, controller  42  may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. 
     In some embodiments, controller  42  is operably connected (e.g., electrically coupled) to heating element  18  and a portion of sealed cooling system  20 , such as the compressor  50 . Controller  42  is configured to selectively and/or separately activate heating element  18  and compressor  50  according to one or more input signals. 
     In certain embodiments, controller  42  is configured to determine a heating condition for cooking utensil  16 . Heating condition may generally correspond to a demand for heat to be generated at heating element  18 . In turn, controller  42  may activate heating element  18  in response to the determined heating condition. In optional embodiments, determination of a heating condition includes receiving a user-selected heating signal from user interface  40 . In additional or alternative embodiments, determination of a heating condition includes determining that a set timing condition has been met, e.g., according to a provided cook cycle. The timing condition for heating element  18  may be predetermined or prescribed according to a selected user input. For instance, the timing condition for heating element  18  may be a selected clock time or an elapsed time period. Heating element  18  may activate at the selected clock time or at the end of the elapsed time period. In still further additional or alternative embodiments, determination of a heating condition includes detecting a temperature threshold (e.g., temperature set point or range). 
     Upon being activated, heating element  18  may continue to operate. Operation may be subsequently ceased as dictated by controller  42 . For instance, controller  42  may determine a stop time has elapsed. The stop time of the heating element  18  may be a selected clock time or an elapsed time period. Heating element  18  may deactivate or cease to operate at the selected clock time or at the end of the elapsed time period. Additionally or alternatively, operation of heating element  18  may be ceased in response to controller  42  detecting a temperature threshold (e.g., temperature set point or range). Optionally, operation of heating element  18  may be ceased in response to determination of a cooling condition. 
     In some embodiments, controller  42  is configured to determine a cooling condition for cooking utensil  16 . Cooling condition may generally correspond to a demand to draw heat away from cooking utensil  16 , e.g., via evaporator  56 . Controller  42  may activate compressor  50  in response to the determined cooling condition. In optional embodiments, determination of a cooling condition includes receiving a user-selected refrigeration signal from user interface  40 . In additional or alternative embodiments, determination of a cooling condition includes determining that a set timing condition has been met, e.g., according to a provided cook cycle. The timing condition for compressor  50  may be predetermined or prescribed according to a selected user input. For instance, the timing condition for compressor  50  may be a selected clock time or an elapsed time period. Compressor  50  may activate at the selected clock time or at the end of the elapsed time period. In still further additional or alternative embodiments, determination of a cooling condition includes detecting a temperature threshold (e.g., temperature set point or range). For instance, compressor  50  may be activated periodically based on a set temperature threshold. 
     Upon being activated, compressor  50  may continue to operate. Operation may be subsequently ceased as dictated by controller  42 . For instance, controller  42  may determine a stop time has elapsed. The stop time of the compressor  50  may be a selected clock time or an elapsed time period. Compressor  50  may deactivate or cease to circulate refrigerant at the selected clock time or at the end of the elapsed time period. Additionally or alternatively, operation of compressor  50  may be ceased in response to controller  42  detecting a temperature threshold (e.g., temperature set point or range). Optionally, operation of compressor  50  may be ceased in response to determination of a heating condition. 
     Activation of compressor  50  may optionally occur before activation of heating element  18 . Additionally or alternatively, activation of compressor  50  may occur after activation of heating element  18 . In some embodiments, multiple unique cooking cycles are provided (e.g., within controller  42 ) to activate heating element  18  and compressor  50  separately according to discrete patterns or cycles of operation. For instance, certain cooking cycles include activating compressor  50  to chill food items within the cooking utensil  16 . After a selected cooling time, compressor  50  is deactivated and heating element  18  is activated to heat the food items. Advantageously, food items may be placed within cooking utensil  16  far in advance of when the food needs to be cooked, while still being held in a reduced preservation temperature. In additional or alternative cooking cycles, activating heating element  18  is included to heat and cook food items within cooking utensil  16 . After food is adequately cooked (e.g., after a selected cooking time), heating element  18  is deactivated and compressor  50  is activated to chill the food items. Advantageously, cooked food items may be stored for extended periods of time within cooking utensil  16 , while still being held in a reduced preservation temperature. 
     Turning now to  FIGS. 3 and 4 , an exemplary evaporator  56  embodiment is illustrated. As shown, evaporator  56  includes a conduit segment  60  to direct refrigerant therethrough. In some embodiments, a rigid conductive plate  70  is provided. When assembled, rigid conductive plate  70  may be in thermal contact with at least a portion of conduit segment  60 . Optionally conduit segment  60  may be fixed to conductive plate  70 . For example, conduit segment  60  may extend through rigid conductive plate  70  between a top surface  72  of rigid conductive plate  70  and a bottom surface  74  of rigid conductive plate  70 . At least a portion of conduit segment  60  may be defined within rigid conductive plate  70 . Additionally or alternatively, conduit segment  60  may include an arcuate and/or serpentine shape. Several passes of conduit segment  60  may be disposed within rigid conductive plate  70  and provide a distributed contact surface with rigid conductive plate  70 . 
     As illustrated in  FIG. 2 , evaporator  56 , which optionally includes rigid conductive plate  70 , may be positioned away from heating element  18 . When cooking utensil  16  is disposed within utensil chamber  14 , evaporator  56  may be positioned between internal base wall  28  and cooking utensil  16 . Top surface  72  may face cooking utensil  16  (e.g., such that bottom surface  74  is in contact with the bottom portion of cooking utensil  16 ). Bottom surface  74  may face away from cooking utensil  16 , e.g., toward internal base wall  28 . One or more conduit apertures  62  may be defined through base wall  28  to permit the passage of conduit to/from additional components of sealed cooling system  20 , e.g., compressor  50  within enclosed cavity. Advantageously, separation between heating element  18  and evaporator  56  may prevent damage to rigid conductive plate  70  and allow for lower heat tolerances in the sealed cooling system  20 . 
     Returning to  FIGS. 3 and 4 , conduit segment  60  and rigid conductive plate  70  may be formed from one or more suitable conductive materials. The materials of conduit segment  60  and rigid conductive plate  70  may be the same, or they may be discrete materials. For instance, conduit segment  60  may be formed from a first conductive material (e.g., copper, steel, or an alloy thereof) while rigid conductive plate  70  is formed from another conductive material (e.g., aluminum or an alloy thereof). In certain embodiments, rigid conductive plate  70  is formed from a suitable conductive material being poured in molten form over conduit segment  60 . Additionally or alternatively, rigid conductive plate  70  may be die cast with conduit segment  60 . 
     In some embodiments, a compressive substrate  76  at least partially supports evaporator  56  (see also  FIG. 2 ). For instance, compressive substrate  76  may be disposed on internal base wall  28 , below rigid conductive plate  70 . Compressive substrate  76  may be positioned between internal base wall  28  and rigid conductive plate  70 . In some such embodiments, bottom surface  74  of rigid conductive plate  70  is disposed on top of compressive substrate  76  (e.g., in contact within compressive substrate  76 ), while internal base wall  28  supports compressive substrate  76  below. When cooking utensil  16  is disposed within utensil chamber  14 , compressive substrate  76  may bias rigid conductive plate  70  toward the bottom portion of cooking utensil  16 , advantageously ensuring thermal contact between evaporator  56  and cooking utensil  16 . Compressive substrate  76  may include one or more suitable elastic structures, such as a foam rubber panel or compression spring, to resiliently deform and/or bias evaporator  56  toward cooking utensil  16 . 
     Turning now to  FIGS. 5 and 6 , another exemplary evaporator  56  is illustrated. As shown, evaporator  56  includes a conduit segment  60  to direct refrigerant therethrough. In some embodiments, a resilient bladder  80  is provided. At least a portion of the conduit segment  60  may extend within the resilient bladder  80 . For example, conduit segment  60  may extend within resilient bladder  80  between a top bladder surface  82  and a bottom bladder surface  84 . 
     In some embodiments, a flowable conductive material  86  may is disposed within resilient bladder  80 . The conductive material  86  may include one or more suitable liquid, fluid, or particulate (e.g., water, propylene glycol, or particulate aluminum). When assembled, the flowable conductive material  86  may surround at least a portion of the conduit segment  60  in fluid isolation from the refrigerant. For instance, in some embodiments the flowable conductive material  86  contacts conduit segment  60  in conductive thermal engagement. Refrigerant may flow through conduit segment  60  without contacting or intermingling with flowable conductive material  86 . Conduit segment  60  may include an arcuate and/or serpentine shape. Several passes of conduit segment  60  may be disposed within resilient bladder  80  and provide a distributed contact surface with flowable conductive material  86 . 
     In some embodiments, evaporator  56 , including resilient bladder  80 , may be positioned away from heating element  18  (see  FIG. 2 ). When cooking utensil  16  is disposed within utensil chamber  14 , evaporator  56  may be positioned between internal base wall  28  and cooking utensil  16 . Top bladder surface  82  may face cooking utensil  16  (e.g., such that bottom surface  74  is in contact with the bottom portion of cooking utensil  16 ). Bottom bladder surface  84  may face away from cooking utensil  16 , e.g., toward internal base wall  28 . One or more conduit apertures  62  (see  FIG. 2 ) may be defined through base wall  28  to permit the passage of conduit to/from additional components of sealed cooling system  20 , e.g., compressor  50  within enclosed cavity. Advantageously, separation between heating element  18  and evaporator  56  may prevent damage to resilient bladder  80  and allow for lower heat tolerances in the sealed cooling system  20 . 
     Resilient bladder  80  may be formed from one or more suitable flexible materials, such as silicone rubber. Conduit segment  60  may be formed from one or more suitable conductive materials (e.g., aluminum, copper, steel, or an alloy thereof). 
     Turning now to  FIG. 7 , a method  200  for operating a slow cooker appliance according to an exemplary embodiment of the present disclosure is illustrated. Method  200  may be used to operate any suitable slow cooker appliance. As an example, method  200  may be used to operate slow cooker appliance  10  (see  FIG. 1 ). Controller  42  (see  FIG. 1 ) may be programmed to implement method  200 . 
     At  210 , method  200  includes determining a heating condition for a cooking utensil. As discussed above, the heating condition may correspond to a demand for heat to be generated and/or provided to cooking utensil. The heating condition may indicate a specific temperature, relative temperature, or a general demand for heat. Determination  210  may be made, for instance, in response to a user input signal. The user input may be made according to an immediate or a delayed desired for heat (e.g., according to a predetermined program). In additional or alternative embodiments,  210  includes determining that a set timing condition has been met, e.g., according to a provided cook cycle. 
     At  220 , method  200  includes activating the heating element to transmit heat to the utensil chamber in response to the determined heating condition at  210 . The heating element may be activated continuously, or according to a predetermined pattern (e.g., a periodic pattern). After the heating element has been activated, the method  200  may provide for deactivating the heating element, as described above. 
     At  230 , method  200  includes determining a cooling condition for the cooking utensil. The cooling condition may indicate a specific temperature, relative temperature, or a general demand for heat. Determination  230  may be made, for instance, in response to a user input signal. The user input may be made according to an immediate or a delayed desired for a reduction in heat (e.g., according to a predetermined program). In additional or alternative embodiments,  230  condition includes determining that a set timing condition has been met, e.g., according to a provided cook cycle. 
     At  240 , method  200  includes activating the compressor to circulate refrigerant within the sealed refrigeration system in response to the determined cooling condition at  230 . The compressor may be activated continuously, are according to a predetermined pattern (e.g., a periodic pattern). After the compressor has been activated, the method  200  may provide for deactivating the compressor, as described above. 
     It is understood that  240  may occur before or after  220 , depending on the desired heating or cooling demands, e.g., according to a provided cook cycle. Moreover, one or more of the method steps  210 ,  220 ,  230 ,  240  may be repeated or reordered without departing from the envisioned method  200 . For example, multiple instances of step  240  may be optionally provided, including one instance of step  240  before step  220 , and another instance of step  240  after step  240  (e.g., according to a predetermined program). 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.