Refrigerator appliance having a defrost chamber

A refrigerator appliance having a defrost chamber is provided herein. The refrigerator appliance may include a cabinet defining a chilled chamber, a defrost drawer housing, and a pair of electromagnetic electrodes. The defrost drawer housing may be mounted within the chilled chamber and define the defrost chamber for the receipt of a food item. The pair of electromagnetic electrodes may be spaced apart along a vertical direction within the drawer housing. Each electromagnetic electrode may include a first heating ring and a second heating ring that is larger than the first heating ring. Each electromagnetic electrode may also include a conductive path and an electrical restrictor element. The conductive path may extend between the first heating ring and the second heating ring. The electrical restrictor element may be coupled to the conductive path and selectively permit a current therethrough.

FIELD OF THE INVENTION

The present subject matter relates generally to refrigerator appliances and more particularly to refrigerator appliances having one or more features for defrosting food items therein.

BACKGROUND OF THE INVENTION

Various methods are presently available to defrost frozen food items. However, these presently available methods to defrost food items generally suffer from certain drawbacks. As an example, frozen food items can be left on a countertop for an extended period of time in order to thaw the food items. While exposed to ambient conditions on the countertop, the food items can enter a food “danger zone” and harmful bacteria can grow within the food items. As another example, frozen food items can be heated in a microwave appliance operating a relatively high frequency [e.g., between 915 and 2450 megahertz (MHz)] in order to thaw the food items. However, heating the food items within the microwave appliance can also partially cook the food items and can negatively affect the taste or texture of the food items. As yet another example, frozen food items can be placed within a fresh food chamber of a refrigerator appliance in order to thaw the food items. Defrosting food items within the fresh food chamber can be time consuming and inconvenient.

Certain items exist for facilitating thawing within a refrigerator appliance. Generally, such items supply additional heat to a portion of the refrigerator appliance in which frozen food items are placed. This additional heat may serve to accelerate the food items. However, such systems are often inefficient. The supply of heat is not narrowly tailored to the food items to be thawed. Moreover, supplying the correct amount of heat is often difficult. Excessive heat may begin cooking the food items, negatively affecting taste or texture. Insufficient heat may fail to adequately thaw the food items, or may take an undesirably long time to completely defrost the food items. If heat is localized to an area too small for the item being defrosted, thawing may be non-uniform.

Accordingly, a refrigerator appliance having features for conveniently defrosting frozen food items would be useful. In particular, a refrigerator appliance that could selectively vary defrosting would be useful.

BRIEF DESCRIPTION OF THE INVENTION

In one exemplary aspect of the present disclosure, a refrigerator appliance is provided. The refrigerator appliance may include a cabinet defining a chilled chamber, a defrost drawer housing, and a pair of electromagnetic electrodes. The defrost drawer housing may be mounted within the chilled chamber. The defrost drawer housing may define an enclosed defrost chamber for the receipt of a food item. The pair of electromagnetic electrodes may be spaced apart along a vertical direction within the drawer housing. Each electromagnetic electrode may include a first heating ring and a second heating ring that is larger than the first heating ring. Each electromagnetic electrode may also include a conductive path and an electrical restrictor element. The conductive path may extend between the first heating ring and the second heating ring. The electrical restrictor element may be coupled to the conductive path and selectively permit a current therethrough.

In another exemplary aspect of the present disclosure, a refrigerator appliance is provided. The refrigerator appliance may include a cabinet defining a chilled chamber, a defrost drawer housing, a pair of electromagnetic electrodes, and a controller. The defrost drawer housing may be mounted within the chilled chamber. The defrost drawer housing may define an enclosed defrost chamber for the receipt of a food item. The pair of electromagnetic electrodes may be spaced apart along a vertical direction within the drawer housing. Each electromagnetic electrode may include a first heating ring and a second heating ring that is concentrically positioned about the first heating ring. The second heating ring may be larger than the first heating ring. Each electromagnetic electrode may also include a conductive path and an electrical restrictor element. The conductive path may extend between the first heating ring and the second heating ring. The electrical restrictor element may be coupled to the conductive path and selectively permit a current therethrough. The controller operably may be coupled to the pair of electromagnetic electrodes. The controller may be configured to direct the current through the electrical restrictor element based on a set heating size.

DETAILED DESCRIPTION

In order to aid understanding of this disclosure, several terms are defined below. The defined terms are understood to have meanings commonly recognized by persons of ordinary skill in the arts relevant to the present subject matter. The term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). The terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

Turning now to the figures,FIGS. 1 and 2,FIG. 1provides a perspective view of a refrigerator appliance100according to an example embodiment of the present disclosure.FIG. 2provides a perspective view of refrigerator appliance100having multiple refrigerator doors128in the open position. As shown, refrigerator appliance100includes a housing or cabinet120that extends between a top101and a bottom102along a vertical direction V. Cabinet120also extends along a lateral direction L and a transverse direction T, each of the vertical direction V, lateral direction L, and transverse direction T being mutually perpendicular to one another. In turn, vertical direction V, lateral direction L, and transverse direction T define an orthogonal direction system.

Cabinet120includes a liner121that defines chilled chambers for receipt of food items for storage. In particular, liner121defines a fresh food chamber122positioned at or adjacent top101of cabinet120and a freezer chamber124arranged at or adjacent bottom102of cabinet120. As such, refrigerator appliance100is generally referred to as a bottom mount refrigerator. It is recognized, however, that the benefits of the present disclosure apply to other types and styles of appliances such as, e.g., a top mount refrigerator appliance, a side-by-side style refrigerator appliance, or a range appliance. Consequently, the description set forth herein is for illustrative purposes only and is not intended to be limiting in any aspect to any particular refrigerator chamber configuration.

Refrigerator doors128are rotatably hinged to an edge of cabinet120for selectively accessing fresh food chamber122. In addition, a freezer door130is arranged below refrigerator doors128for selectively accessing freezer chamber124. Freezer door130is attached to a freezer drawer (not shown) slidably mounted within freezer chamber124. Refrigerator doors128and freezer door130are shown in the closed configuration inFIG. 1.

In some embodiments, refrigerator appliance100also includes a dispensing assembly140for dispensing liquid water or ice. Dispensing assembly140includes a dispenser142positioned on or mounted to an exterior portion of refrigerator appliance100(e.g., on one of refrigerator doors128). Dispenser142includes a discharging outlet144for accessing ice and liquid water. An actuating mechanism146, shown as a paddle, is mounted below discharging outlet144for operating dispenser142. In alternative exemplary embodiments, any suitable actuating mechanism may be used to operate dispenser142. For example, dispenser142can include a sensor (such as an ultrasonic sensor) or a button rather than the paddle. A user interface panel148is provided for controlling the mode of operation. For example, user interface panel148includes a plurality of user inputs (not labeled), such as a water dispensing button and an ice-dispensing button (e.g., for selecting a desired mode of operation such as crushed or non-crushed ice).

Discharging outlet144and actuating mechanism146are an external part of dispenser142and are mounted in a dispenser recess150. Dispenser recess150is positioned at a predetermined elevation convenient for a user to access ice or water and enabling the user to access ice without the need to bend-over and without the need to open refrigerator doors128.

Operation of the refrigerator appliance100can be generally controlled or regulated by a controller190. As will be described in greater detail below, controller190may include multiple modes of operation or sequences that control or regulate various portions of refrigerator appliance100according to one or more discrete criteria.

In some embodiments, controller190is operably coupled (e.g., electrically coupled or wirelessly coupled) to user interface panel148or various other components, as will be described below. User interface panel148provides selections for user manipulation of the operation of refrigerator appliance100. As an example, user interface panel148may provide for selections between whole or crushed ice, chilled water, or specific operations, such as a defrost routine. In response to one or more input signals (e.g., from user manipulation of user interface panel148or one or more sensor signals), controller190may operate various components of the refrigerator appliance100.

Controller190may include a memory (e.g., non-transitive media) and one or more 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 refrigerator appliance100. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In some embodiments, the processor executes programming instructions stored in memory. For certain embodiments, the instructions include a software package configured to operate appliance100and, for example, execute a defrost routine including the exemplary method600described below with reference toFIG. 6. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller190may 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.

Controller190, or portions thereof, may be positioned in a variety of locations throughout refrigerator appliance100. In example embodiments, controller190is located within the user interface panel148. In other embodiments, the controller190may be positioned at any suitable location within refrigerator appliance100, such as within a fresh food chamber, a freezer door, etc. In additional or alternative embodiments, controller190is formed from multiple components mounted at discrete locations within or on refrigerator appliance100. Input/output (“I/O”) signals may be routed between controller190and various operational components of refrigerator appliance100. For example, user interface panel148may be operably coupled (e.g., electrically coupled) to controller190via one or more signal lines or shared communication busses.

According to the illustrated embodiment, various storage components are mounted within fresh food chamber122to facilitate storage of food items therein as will be understood by those skilled in the art. In particular, the storage components include storage bins166, drawers168, and shelves170that are mounted within fresh food chamber122. Storage bins166, drawers168, and shelves170are configured for receipt of food items (e.g., beverages or solid food items) and may assist with organizing such food items. As an example, drawers168can receive fresh food items (e.g., vegetables, fruits, and/or cheeses) and increase the useful life of such fresh food items. As another example, one or more drawers168can be provided as part of a defrost assembly to receive frozen food items (e.g., frozen meats, soups, etc.), which is described in detail below.

Turning now toFIG. 3, an exemplary defrost assembly200is illustrated. As shown, in some embodiments, defrost assembly200includes a defrost drawer housing202for receiving items within an enclosed drawer chamber204. It is understood that defrost drawer housing202may be provided with, or in place of, a drawer (e.g., drawers168) within fresh food chamber122or freezer chamber124.

As may be seen inFIG. 3, defrost drawer housing202generally extends between a top portion206and a bottom portion208(e.g., along the vertical direction V). A top wall210of drawer housing202is positioned at or adjacent top portion206of drawer housing202, and a bottom wall212of defrost drawer housing202is positioned at or adjacent bottom portion208of defrost drawer housing202. Thus, top and bottom walls210,212of defrost drawer housing202may be spaced apart from each other (e.g., along the vertical direction V). Defrost drawer housing202also includes side walls214that extend between top and bottom walls210,212of defrost drawer housing202(e.g., along the vertical direction V). Top wall210, bottom wall212and side walls214may assist with defining defrost chamber204of defrost drawer housing202.

Defrost drawer housing202also includes a door216that permits selective access to defrost chamber204of defrost drawer housing202. For instance, door216may be provided as a slidable drawer having one or more mutually-fixed panels218defining a sub-compartment that may be positioned inside of drawer chamber204and within which one or more food items198may be placed. In turn, door216, including panels218, may slide (e.g., along the transverse direction T) between an open position permitting access to drawer chamber204and closed position restricting access to drawer chamber204. Nonetheless, it is understood that other configurations of door216may be provided (e.g., as an outward pivoting door, upward pivoting door, independently slidable door, etc.) to selectively open and close drawer chamber204.

In certain embodiments, defrost drawer housing202(e.g., top wall210, bottom wall212, and side walls214of defrost drawer housing202) is insulated such that drawer chamber204of defrost drawer housing202and food items198positioned therein may be heated (e.g., without significantly heating fresh food chamber122or freezer chamber124). As an example, top wall210, bottom wall212, or side walls214of defrost drawer housing202may include vacuum insulation panels, insulating foam, fiberglass insulation, etc. to assist with insulating defrost drawer housing202. Thus, drawer chamber204of defrost drawer housing202may be thermally isolated from fresh food chamber122or freezer chamber124within which drawer housing202is mounted. Moreover, heat transfer between drawer chamber204of defrost drawer housing202and fresh food chamber122or freezer chamber124may be limited or hindered by defrost drawer housing202.

A pair of electromagnetic electrodes (e.g., a top electrode220A and a bottom electrode220B) is generally positioned within drawer housing202. In particular, top electrode220A is spaced apart from bottom electrode220B (e.g., along the vertical direction V) within drawer chamber204. In some such embodiments, top and bottom electrodes220A,220B are supported by separate planar members. For instance, top electrode220A may be fixed to (e.g., directly on or within) an upper platen224below top wall210. Bottom electrode220B may be fixed to (e.g., directly on or within) a lower platen226above bottom wall212. Optionally, lower platen226may rest on a supporting insulator material228that fills the space between bottom wall212and lower platen226(e.g., beneath panels218). Additionally or alternatively, lower platen226may be further separated from panel by a shelf232formed of any suitable low loss dielectric material, such as a glass-ceramic material.

In some embodiments, the space (e.g., vertical space) between top electrode220A and bottom electrode220B is variable. A vertical lift232may act to move upper platen224within the drawer housing202(e.g., parallel to lower platen226) between multiple positions of varying proximity to bottom wall212or lower platen226. In the exemplary embodiments ofFIG. 3, vertical lift232is generally provided as a scissor jack. However, it is understood that any other suitable actuating assembly (e.g., linear actuator, pulley system, rack and pinion, etc.) may be provided to move upper platen224or top electrode220A along the vertical direction V.

As generally illustrated, top electrode220A and bottom electrode220B are each operably coupled (e.g., electrically coupled via one or more conductive signal lines or busses) to controller190. Together, top electrode220A and bottom electrode220B may form a radio frequency (RF) heating pair. In turn, controller190may be configured to direct an electric current [e.g., RF current between 10 and 100 megahertz (MHz)] between top electrode220A and bottom electrode220B. As is generally understood, the electric current may induce an electric field to heat or defrost food items198(e.g., consumable high loss dielectric materials) positioned between top electrode220A and bottom electrode220B.

Generally, each electromagnetic electrode220A,220B may be provided as matched or corresponding bodies. In turn, the shape or structure of top electrode220A may mirror the shape or structure of bottom electrode220B. As illustrated inFIG. 4, each electromagnetic electrode220may include multiple conductive heating rings (e.g., heating rings240,242,244) electrically connected by one or more conductive paths246,248. For instance, a first heating ring240of an electromagnetic electrode220may be surrounded (e.g., along a plane perpendicular to the vertical direction V) by a second heating ring242. In other words, the second heating ring242may be positioned radially outward from a center point C of first heating ring240. Thus, second heating ring242is larger (e.g., in diameter) than first heating ring240. Optionally, one or more additional heating rings (e.g., a third heating ring244) may be included around second heating ring242. Thus, a third heating ring244may be larger (e.g., in diameter) than second heating ring242.

Conductive heating rings (e.g., heating rings240,242,244) may be generally provided as any suitable continuous shape. As used in the context of electromagnetic electrodes, the term “ring” may indicate a generally toroidal structure (e.g., a toroidal polyhedron having a single central hole, such as that illustrated at second heating ring242) or a generally solid structure (e.g., a void-free polyhedron having no visible hole, such as that illustrated at first heating ring240). Thus, as illustrated, conductive heating rings240,242,244may be generally formed about a center point C. In some such embodiments, each conductive heating ring240,242,244of electromagnetic electrode220is mutually-concentric such that a constant radial gap is defined between the perimeters of adjacent heating rings. As used in the context of heating rings, “adjacent” is understood to indicate a heating ring that is positioned immediately and sequentially inward or outward (e.g., along the radial direction R) from another heating ring. Thus, air or an insulating material may occupy the space between an outer radial edge of one heating ring (e.g., first heating ring240) and an inner radial edge of a larger adjacent heating ring (e.g., second heating ring242). Optionally, the radial gap between each adjacent concentric ring pair may be identical or, alternatively, unique.

A conductive path generally extends (e.g., through the radial gap) between adjacent heating rings (e.g.,240and242or242and244). Thus, as shown, a first conductive path246extends radially between first heating ring240and second heating ring242; and a second conductive path248extends radially between second heating ring242and third heating ring244. Each conductive path is formed from a conductive (e.g., electrically conductive) material such that an electrical current (e.g., RF current) may be conducted between adjacent heating rings.

In some embodiments, each electromagnetic electrode220includes one or more electrical restrictor elements (e.g., restrictor elements250,252). In particular, an electrical restrictor element (e.g., restrictor element250or252) may be coupled to a corresponding conductive path (e.g., in series between adjacent heating rings240and242or242and244).

Generally, each electrical restrictor element (e.g., restrictor elements250,252) is configured to selectively permit or restrict the electrical current through the corresponding conductive path (i.e., between adjacent heating rings). Thus, electrical restrictor element250or252may alternate between an opened and closed configuration. In the opened configuration, an electrical current or signal is prevented from flowing through the restrictor element and thereby the corresponding conductive path. In the closed configuration, an electrical current or signal is permitted to flow through the restrictor element and thereby the corresponding conductive path.

In certain embodiments, electrical restrictor element250or252is a gate switch (e.g., normally open switch, normally closed switch, etc.). Controller190may selectively direct the gate switch to open or close. In other embodiments, electrical restrictor element250or252is a narrow band pass filter, which limits electric currents therethrough to those above a predetermined frequency threshold (i.e., such that only currents having a frequency above the predetermined frequency threshold may pass through electrical restrictor element250or252). In embodiments having multiple discrete electrical restrictor elements (e.g., restrictor elements250and252) coupled to separate conductive paths (e.g., conductive paths246and248), each electrical restrictor element (e.g., restrictor element250or252) may be the same or, alternatively, unique from one or more of the other electrical restrictor elements (e.g., restrictor element252or250). As an example, first restrictor element250may be a gate switch while second restrictor element252is a narrow band pass filter. Further electrical restrictor elements may be any suitable element.

As shown, a separate electrical restrictor element250or252may be coupled to each discrete conductive path246or248. For instance, a first restrictor element250may be coupled to first conductive path246while a second restrictor element252is coupled to second conductive path248. However, in alternative embodiments, certain conductive paths may not have any corresponding restrictor element and are, thus, generally unrestricted to permit an electrical current (e.g., RF current) between adjacent heating rings.

In some embodiments, controller190is configured to selectively direct a current to the pair of electromagnetic electrodes220A,220B (FIG. 3). For instance, as is understood, controller190may include an RF circuit (not pictured) to direct an RF current (e.g., between 10 MHz and 100 MHz) to top electrode220A and bottom electrode220B such that an alternating electric field heats a dielectric material (e.g., food items198) positioned between top electrode220A and bottom electrode220B. Optionally, the controller190may vary its own operations based on the size (e.g., length or width perpendicular to the vertical direction V) of food items198to be defrosted. In certain embodiments, controller190is configured to selectively direct the RF current based on a set heating size. Transmission of the RF current from controller190through the pair of electromagnetic electrodes220may thus be contingent on or influenced by the set heating size.

Referring still toFIG. 4, in exemplary embodiments, the controller190is configured to separately direct the current flow through each electrical restrictor element250,252based on the set heating size. Whether the RF current is permitted to certain heating rings (i.e., through an upstream electrical restrictor element) may be determined according to the set heating size. During use, the number of heating rings240,242,244that receive the RF current, and thus generate an electrical field, may be generally correlated to the set heating size. As the set heating size increase, so too might the number of heating rings240,242,244that receive the RF current. Advantageously, such defrost assemblies may ensure efficient defrosting and prevent or limit “runaway heat” where outer fringes of defrosting food items are overheated.

In exemplary embodiments, such as those wherein one or more electrical restrictor elements (e.g., first restrictor element250and second restrictor element252) is a gate switch, controller190may be configured to open or close the gate switch according to the set heating size. As an example, at a first heating size, controller190may transmit the RF current and direct the first restrictor element250of each electromagnetic electrode220to be opened, breaking the circuit between the corresponding first heating ring240and second heating ring242. Thus, the RF current is restricted to the first heating ring240. At a second heating size that is larger than the first heating size, controller190may transmit the RF current and direct the first restrictor element250of each electromagnetic electrode220to be closed, connecting the circuit between the corresponding first heating ring240and second heating ring242. Thus, the RF current is permitted to flow through both the first heating ring240and the second heating ring242. Controller190may direct the second restrictor element252of each electromagnetic electrode220to be opened. At a third heating size that is larger than the second heating size, controller190may transmit the RF current and direct the first restrictor element250and second restrictor element252of each electromagnetic electrode220to be closed, connecting the circuit between the corresponding first heating ring240, second heating ring242, and third heating ring244. Thus, the RF current is permitted to flow through each of the first heating ring240, the second heating ring242, and the third heating ring244.

In further exemplary embodiments, such as those wherein one or more electrical restrictor elements (e.g., first restrictor element250and second restrictor element252) is a narrow band filter, controller190may be configured to vary the frequency of the RF current according to the set heating size. In some such embodiments, the narrow bandpass filter of each first restrictor element250has a frequency threshold that is lower than the frequency threshold of the narrow bandpass filter of each second restrictor element252. As an example, at a first heating size, controller190may transmit the RF current at a first frequency (e.g., 27 MHz) that is lower than the frequency threshold of the first restrictor element250. Thus, the RF current is restricted to the first heating ring240. At a second heating size that is larger than the first heating size, controller190may transmit the RF current at a second frequency (e.g., 32 MHz) that is greater than or equal to the frequency threshold of the first restrictor element250and less than the frequency threshold of the second restrictor element252. Thus, the RF current is permitted to flow through both the first heating ring240and the second heating ring242, while being restricted from passing to the third heating ring244. At a third heating size that is larger than the second heating size, controller190may transmit the RF current at a second frequency (e.g., 43 MHz) that is greater than the frequency threshold of the first restrictor element250and that is greater than or equal to the frequency threshold of the second restrictor element252. Thus, the RF current is permitted to flow through each of the first heating ring240, the second heating ring242, and the third heating ring244.

In still further exemplary embodiments, such as those wherein at least one restrictor element (e.g., first restrictor element250) is a gate switch and at least one other restrictor element (e.g., second restrictor element252) is a narrow band filter, controller190may be configured to separately direct the current flow through each electrical restrictor element250,252based on the set heating size. As an example, at a first heating size, controller190may transmit the RF current and direct the first restrictor element250of each electromagnetic electrode220to be opened, breaking the circuit between the corresponding first heating ring240and second heating ring242. Thus, the RF current is restricted to the first heating ring240. At a second heating size that is larger than the first heating size, controller190may transmit the RF current and direct the first restrictor element250of each electromagnetic electrode220to be closed, connecting the circuit between the corresponding first heating ring240and second heating ring242. Thus, the RF current is permitted to flow through both the first heating ring240and the second heating ring242. At the second heating size, controller190may transmit the RF current at a first frequency (e.g., 27 MHz) that is lower than the frequency threshold of the narrow band pass filter of the second restrictor element252. At a third heating size that is larger than the second heating size, controller190may direct the first restrictor element250of each electromagnetic electrode220to be closed. Moreover, controller190may transmit the RF current at a second frequency (e.g., 32 MHz) that is greater than or equal to the frequency threshold of the second restrictor element252. Thus, the RF current is permitted to flow through each of the first heating ring240, the second heating ring242, and the third heating ring244.

Referring toFIGS. 3 and 5, in some embodiments, controller190is further configured to determine the set heating size based on one or more received sizing signals. The heating size specified by the user may be a general estimation of relative size (e.g., small, medium, large, etc.) or may correspond to a measured geometric dimension (e.g., length, width, height, etc.).

As an example, a user may specify a certain heating size at the inputs of user interface panel148, which may be transmitted from user interface panel148as a sizing signal. In turn, controller190may receive the sizing signal and direct the RF current accordingly.

As another example, the pair of electromagnetic electrodes (e.g., first electrode220A and second electrode220B) may detect an electric field before transmission of the RF current from controller190. In particular, one or more of the electromagnetic electrodes220A,220B may detect variations in, for example, capacitance or resistance, across the heating rings240,242,244. Such variations may be attributable to and indicative of food items198positioned between top electrode220A and bottom electrode220B (e.g., directly on top of lower platen226). Moreover, the controller190may read or receive these variations as an electrical field signal, and from the received electrical field signal, automatically determine a desirable set heating size (e.g., without further user input).

As yet another example, a secondary sizing sensor260may be provided within drawer chamber204, as illustrated inFIG. 5, and operably coupled to controller190. Generally, secondary sizing sensor260may be any suitable discrete sensor for detecting one or more geometric dimensions (e.g., length, width, height, etc.) of food items198between top electrode220A and bottom electrode220B. For example, secondary sizing sensor260may include an infrared or optical sensor mounted to defrost assembly200(e.g., on top of upper platen224to detect an image of the space therebelow). In some such embodiments, the controller190is configured to receive the sizing signal (e.g., as an image signal) from secondary sizing sensor260. Moreover, from the received sizing signal, controller190may automatically determine a desirable set heating size (e.g., without further user input).

Turning now toFIG. 6, a flow chart is provided of a method600according to exemplary embodiments of the present disclosure. Generally, the method600provides an exemplary defrost routine for any suitable refrigeration appliance, such as refrigerator appliance100(FIG. 1), described above (e.g., to defrost food items198within fresh food chamber122). The method600can be performed, for instance, by the controller190(FIG. 1). As discussed above, controller190may be operably coupled to user interface panel148. Moreover, controller190may be operably coupled to defrost assembly200at top electrode220A and bottom electrode220B, each of which includes one or more heating rings (e.g., heating rings240,242,244) and restrictor elements (e.g., restrictor elements250,252) (FIGS. 3 and 5). Optionally, controller190may also be operably coupled to defrost assembly200at secondary sizing sensor260(FIG. 5). During operations, controller190may send signals to and receive signals from user interface panel148and defrost assembly200. Controller190may further be operably coupled to other suitable components of the appliance100to facilitate operation of the appliance100generally.

FIG. 6depicts steps performed in a particular order for purpose of illustration and discussion. Those of ordinary skill in the art, using the disclosures provided herein, will understand that the steps of any of the methods disclosed herein can be modified, adapted, rearranged, omitted, or expanded in various ways without deviating from the scope of the present disclosure, except as otherwise indicated.

At610, the method600includes placing or positioning a food item within the defrost chamber of the defrost assembly. As an example, a user of the refrigerator appliance may place a frozen food item, such as chicken, soup, etc., within the defrost chamber. As discussed above, the defrost assembly is positioned or disposed within a chilled chamber, such as the fresh food chamber. Thus, a temperature of the defrost chamber may be about equal to (e.g., equal to) a temperature of the chilled chamber.

At620, the method600includes initiating a defrost operation. As an example, a user of the refrigerator appliance may initiate the defrosting operation at620with the user interface panel.

Method600may also include establishing or ascertaining a desired completion time for the defrosting operation (e.g., at or before620). For example, a user of the refrigerator appliance may utilize the user interface panel to manually input or establish the desired completion time for the defrosting operation to controller. Controller may be configured or programmed to initiate the defrosting operation at620such that the defrosting operation is complete and the food item within the defrost chamber of defrost assembly is suitably defrosted by the desired completion time for the defrosting operation (e.g., prior to a time a user of the refrigerator appliance would like to start cooking the food item within the defrost drawer chamber of drawer housing).

At630, the method600includes determining a set heating size. In some embodiments, the set heating size at630is based on one or more received sizing signals, as described above. For instance, the received sizing signal may be a user-selected input signal transmitted from the user interface. Alternatively, the sizing signal may be automatically generated without any user input or estimation. As an example, the received sizing signal may be an electrical field signal detected at, and received from, one or both of the electromagnetic electrodes. As another example, the received signal may be received from a secondary sizing sensor (e.g., as an image signal), as described above. Optionally,630may be executed in response to initiating the defrost routine such that the set heating size is determined after (e.g., directly or indirectly after)620.

At640, the method includes directing a current (e.g., RF current) to the pair of electromagnetic electrodes based on the set heating size determined at630. As described above, controller may separately direct the current flow through one or more electrical restrictor elements of each electromagnetic electrode (e.g., simultaneously). Generally,640may provide for increasing/decreasing the number of heating rings active (i.e., subject to the RF current) with the relative increase/decrease of the set heating size. As an example, if a gate switch is provided as a restrictor element,640may include selectively closing the gate switch based on the set heating size. As an additional or alternative example, if a narrow band filter is provided as a restrictor element,640may include selectively adjusting the frequency of the current based on the set heating size.

At650, the method600includes determining whether the defrosting operation is complete. As an example, the controller may determine that the defrosting operation is complete if the period of the defrosting operation has elapsed. The defrosting operation is continued until the defrosting operation is complete at step650.

When the defrosting operation is complete, the controller may alert (i.e., transmit an alert signal to) the user of refrigerator appliance at660. Generally, the user may be alerted using any suitable method or mechanism at660. As an example, the controller may present a message on display of refrigerator appliance at660to alert the user that the defrosting operation is complete. Additionally or alternatively, an audio signal or alert may be projected from a speaker at the user interface.