REFRIGERATOR APPLIANCE WITH ENHANCED ODOR CONTROL

Abstract

A refrigerator appliance includes a cabinet defining a food storage chamber. A method of operating the refrigerator appliance includes operating a fan of the refrigerator appliance at a first level during a normal mode. The first level is determined by a call for cooling based on a set temperature for the food storage chamber. The method also includes operating the fan at a second level greater than the first level during an enhanced odor control mode.

Description

FIELD OF THE INVENTION

The present subject matter relates generally to refrigerator appliances, and more particularly to systems and methods for reducing or eliminating perceptible odors in such refrigerator appliances, e.g., which may be generated by items stored therein.

BACKGROUND OF THE INVENTION

Refrigerator appliances generally include a cabinet that defines a chilled chamber. A wide variety of food items may be stored within the chilled chamber. The low temperature of the chilled chamber relative to ambient atmosphere assists with increasing a shelf life of the food items stored within the chilled chamber.

Various food items, such as produce items (e.g., fruits and vegetables), meats, cheeses, or herbs (e.g., onion or garlic), stored in a refrigerator appliance may emit user-perceptible odors. In particular, some such food items may emit user-perceptible odors, or increasing levels of user-perceptible odors, as they go through various physical and chemical changes over time, e.g., ripening fruit, aging meat or cheese, etc. The presence of such user-perceptible odors is generally not desired as the odors may be unpleasant or annoying to at least some users.

Accordingly, a refrigerator appliance with systems for improved odor management, e.g., reducing or eliminating user-perceptible odors within the refrigerator appliance, would be useful.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In an exemplary embodiment, a method of operating a refrigerator appliance is provided. The refrigerator appliance includes a cabinet defining a food storage chamber therein. The method includes operating a fan of the refrigerator appliance at a first level during a normal mode. The first level is determined by a call for cooling based on a set temperature for the food storage chamber. The method also includes operating the fan at a second level greater than the first level during an enhanced odor control mode.

In another exemplary embodiment, a refrigerator appliance is provided. The refrigerator appliance includes a cabinet defining a food storage chamber therein, a fan, and a controller. The controller is configured for operating the fan at a first level during a normal mode. The first level is determined by a call for cooling based on a set temperature for the food storage chamber. The controller is also configured for operating the fan at a second level greater than the first level during an enhanced odor control mode.

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 front view of a refrigerator appliance according to one or more exemplary embodiments of the present subject matter.

FIG. 2 provides a perspective view of the refrigerator appliance of FIG. 1.

FIG. 3 provides a front view of the refrigerator appliance of FIG. 1 with doors thereof in an open position.

FIG. 4 provides a schematic illustration of an example sealed cooling system as may be used with a refrigerator appliance in one or more exemplary embodiments of the present subject matter.

FIG. 5 is a perspective view of a portion of a sub-assembly for a refrigerator appliance according to one or more exemplary embodiments of the present subject matter which may be incorporated into a refrigerator appliance such as the exemplary refrigerator appliance of FIG. 1.

FIG. 6 is a close-up view of an air grille in the sub-assembly of FIG. 5.

FIG. 7 is a view of the air grille of FIG. 6 with a filter cover thereof in an open position.

FIG. 8 provides a flow diagram of an exemplary method for operating a refrigerator appliance according to one or more exemplary embodiments of the present subject matter.

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.

FIG. 1 is a front view of an exemplary embodiment of a refrigerator appliance 100. FIG. 2 is a perspective view of the refrigerator appliance 100. FIG. 3 is a front view of the refrigerator appliance 100 with fresh food doors 128 thereof in an open position. Refrigerator appliance 100 extends between a top 101 and a bottom 102 along a vertical direction V. Refrigerator appliance 100 also extends between a first side 105 and a second side 106 along a lateral direction L. As shown in FIG. 2, a transverse direction T may additionally be defined perpendicular to the vertical and lateral directions V and L. Refrigerator appliance 100 extends along the transverse direction T between a front portion 108 and a back portion 110.

Refrigerator appliance 100 includes a cabinet or housing 120 defining an upper fresh food chamber 122 (FIG. 3) and a lower freezer chamber or frozen food storage chamber 124 arranged below the fresh food chamber 122 along the vertical direction V. In some embodiments, an auxiliary food storage chamber (not shown) may be positioned between the fresh food chamber 122 and the frozen food storage chamber 124, e.g., along the vertical direction V. Because the frozen food storage chamber 124 is positioned below the fresh food chamber 122, refrigerator appliance 100 is generally referred to as a bottom mount refrigerator. In the exemplary embodiment, housing 120 also defines a mechanical compartment (not shown) for receipt of a sealed cooling system (not shown). Using the teachings disclosed herein, one of skill in the art will understand that the present invention can be used with other types of refrigerators (e.g., side-by-sides) as well. Consequently, the description set forth herein is for illustrative purposes only and is not intended to limit the invention in any aspect.

Refrigerator doors 128 are each rotatably hinged to an edge of housing 120 for accessing fresh food chamber 122. It should be noted that while two doors 128 in a “French door” configuration are illustrated, any suitable arrangement of doors utilizing one, two or more doors is within the scope and spirit of the present disclosure. A freezer door 130 is arranged below refrigerator doors 128 for accessing freezer chamber 124. In the exemplary embodiment, freezer door 130 is coupled to a freezer drawer (not shown) slidably mounted within freezer chamber 124. An auxiliary door 127 may be coupled to an auxiliary drawer (not shown) which is slidably mounted within the auxiliary chamber (not shown).

Operation of the refrigerator appliance 100 can be regulated by a controller 134 that is operatively coupled to a user interface panel 136. User interface panel 136 provides selections for user manipulation of the operation of refrigerator appliance 100 to modify environmental conditions therein, such as temperature selections, etc. In some embodiments, user interface panel 136 may be proximate to a dispenser assembly 132. Panel 136 provides selections for user manipulation of the operation of refrigerator appliance 100 such as, e.g., temperature selections, selection of automatic or manual override humidity control (as described in more detail below), etc. In response to user manipulation of the user interface panel 136, the controller 134 operates various components of the refrigerator appliance 100. Operation of the refrigerator appliance 100 can be regulated by the controller 134, e.g., controller 134 may regulate operation of various components of the refrigerator appliance 100 in response to programming and/or user manipulation of the user interface panel 136.

The controller 134 may include a memory 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 appliance 100. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. It should be noted that controllers 134 as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein.

The controller 134 may be positioned in a variety of locations throughout refrigerator appliance 100. In the illustrated embodiment, the controller 134 may be located within the door 128. In such an embodiment, input/output (“I/O”) signals may be routed between the controller and various operational components of refrigerator appliance 100. In one embodiment, the user interface panel 136 may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the user interface 136 may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 136 may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. For example, the user interface 136 may include a touchscreen providing both input and display functionality. The user interface 136 may be in communication with the controller via one or more signal lines or shared communication busses.

As may be seen in FIG. 3, a plurality of food storage elements, such as bins 138, shelves 142, and drawers 140 are disposed within the fresh food storage chamber 122. As will be described in more detail below, the drawers 140 may be configured for storing produce, such as fruits and vegetables, and, in particular, the refrigerator appliance may be operable to provide, and configured for providing, improved shelf life of the produce stored therein. Thus, the drawers 140 may also be referred to as produce drawers 140 or as a vegetable drawer 140 and a fruit drawer 140. For example, in some embodiments, the refrigerator appliance may include two drawers 140, e.g., as illustrated in FIG. 3.

Using the teachings disclosed herein, one of skill in the art will understand that the present subject matter can be used with other types of refrigerators such as a refrigerator/freezer combination, side-by-side, bottom mount, compact, and any other style or model of refrigerator appliance. Accordingly, other configurations of refrigerator appliance 100 could be provided, it being understood that the configurations shown in the accompanying FIGS. and the description set forth herein are by way of example for illustrative purposes only.

FIG. 4 provides a schematic view of the refrigerator appliance 100, in particular the sealed cooling system 60 thereof. As illustrated in FIG. 4, refrigerator appliance 100 includes a mechanical compartment 62 that at least partially contains components for executing a known vapor compression cycle for cooling air. The components include a compressor 64, a heat exchanger or condenser 66, an expansion device 68, and an evaporator 70 connected in series and charged with a refrigerant. Evaporator 70 is also a type of heat exchanger which transfers heat from air passing over the evaporator to a refrigerant flowing through evaporator 70 thereby causing the refrigerant to vaporize. As such, cooled air C is produced and configured to refrigerate chambers 122 and 124 of refrigerator appliance 100. The cooled air C may be directed to the food storage chambers 122 and 124 by a fan 74.

From evaporator 70, vaporized refrigerant flows to compressor 64, which operates to increase the pressure of the refrigerant. This compression of the refrigerant raises its temperature, which is lowered by passing the gaseous refrigerant through condenser 66 where heat exchange with ambient air takes place so as to cool the refrigerant. A fan 72 is used to pull air across condenser 66, as illustrated by arrows A, so as to provide forced convection for a more rapid and efficient heat exchange between the refrigerant and the ambient air.

Expansion device 68 further reduces the pressure of refrigerant leaving condenser 66 before being fed as a liquid to evaporator 70. Collectively, the vapor compression cycle components in a refrigeration circuit, associated fans, and associated compartments are sometimes referred to as a sealed refrigeration system operable to force cold air through refrigeration chambers 122 and 124. The refrigeration system 60 depicted in FIG. 4 is provided by way of example only. It is within the scope of the present invention for other configurations of the refrigeration system to be used as well. For example, fan 74 may be repositioned so as to push air across evaporator 70, dual evaporators may be used with one or more fans, and numerous other configurations may be applied as well.

FIG. 5 illustrates an exemplary sub-assembly for a refrigerator appliance, such as the exemplary refrigerator appliance 100 described above. The sub-assembly may include an internal wall, e.g., a back wall 123. The back wall 123 may be an internal wall of the refrigerator appliance 100 and, as such, may define a portion of a food storage chamber therein such as the fresh food chamber 122. A storage component such as shelf 142 may be mounted to the back wall 123 and the sub-assembly may further include a plurality of walls 210, such that the storage drawers 140 (FIG. 3) may be mounted to the sub-assembly, e.g., slidably mounted to and between the walls 210. As illustrated in FIG. 5, the storage drawers 140 (FIG. 3) are removed from the sub-assembly, and a grille 200 formed in the back wall 123 may be seen with the drawers 140 removed. In various embodiments, the grille 200 may be formed in different locations on the back wall 123 and/or in a different internal wall of the fresh food chamber 122 (or other food storage chamber in the refrigerator appliance) as well as or instead of the illustrated location. The grille 200 includes a plurality of apertures 202 which may provide fluid communication between the food storage chamber, e.g., fresh food chamber 122, and other internal components of the refrigerator appliance 100. For example, thermal insulation, e.g., foam, may be provided between the internal walls, such as back wall 123, and the cabinet 120, with ducts or other passageways or conduits also extending through the space between the internal walls and the cabinet 120, such as air ducts by which the cooled air C travels to the fresh food chamber 122 and enters the fresh food chamber 122 through the grille 200, e.g., through one or more of the apertures 202 thereof. Thus, for example, the grille 200 may provide or permit fluid communication between the sealed cooling system 60, in particular the evaporator 70, and the fresh food chamber 122, e.g., such that cooled air C flows into the fresh food chamber 122 from the evaporator 70 through the grille 200, such as the cooled air C may be urged through the grille 200 by the fan 74.

Turning now to FIGS. 6 and 7, the grille 200 may also include a filter cover 206. An air filter 204 (FIG. 7) may be removably received within the filter cover 206. Thus, when the air filter 204 is received within the filter cover 206 of the grille 200, the air filter 204 may thereby be positioned upstream of the fresh food chamber 122 with respect to the flow of cooled air C, such that air flowing into and/or circulating within the fresh food chamber 122 passes over and/or through the air filter 204, and the air filter 204 may thusly filter the air, e.g., reduce or remove odor-causing substances from the air flowing into and/or circulating within the fresh food chamber 122 (or other food storage chamber). As seen in FIG. 7 in particular, the air filter 204 may be slidable within and from the filter cover 206, e.g., along direction 1000 to remove the air filter 204, such as for maintenance, e.g., whereby the air filter 204 may be cleaned or replaced periodically as needed.

The air filter 204 may be any suitable air filter, e.g., may include one or more air filtration media, such as activated carbon, zeolite, or other similar media, including filter media with an additive or coating, such as a permanganate additive. For example, an activated carbon with a permanganate additive may advantageously promote increased adsorption of gasses having relatively smaller molecules as compared to gasses adsorbed by activated carbon alone. In various embodiments, the air filter 204 may include granular activated carbon (GAC), agglomerated activated carbon (AAC), or other carbon filter media.

Now that the construction and configuration of refrigerator appliance 100 have been presented according to an exemplary embodiment of the present subject matter, exemplary methods for operating a refrigerator appliance, such as refrigerator appliance 100, are provided. In this regard, for example, controller 134 may be configured for implementing one or more of the following exemplary methods. However, it should be appreciated that the exemplary methods are discussed herein only to describe exemplary aspects of the present subject matter, and are not intended to be limiting.

Turning now to FIG. 8, embodiments of the present disclosure may include a method 800 of operating a refrigerator appliance, such as the exemplary refrigerator appliance 100 described above. For example, the refrigerator appliance may include a controller and a cabinet defining a food storage chamber therein. Also by way of example, the refrigerator may further include a fan, e.g., an evaporator fan such as fan 74 described above, for example.

As shown in FIG. 8, method 800 may also include, at step 810, operating a fan of the refrigerator appliance at a first level during a normal mode. When the refrigerator appliance is operating in the normal mode, the operation of the fan is based on the desired temperature within the food storage chamber, such as may be indicated by or correspond to a user-determined set temperature for the food storage chamber (e.g., fresh food chamber). Thus, the first level at which the fan is operated may be determined by a call for cooling based on the set temperature for the food storage chamber. For example, when the set temperature is relatively high, the call for cooling may be less and accordingly the first level of the fan may be or include a slower speed or shorter on time, and/or other relatively low level of fan operation.

In some embodiments, the exemplary method 800 may also include a step 820 of operating the fan at a second level greater than the first level during an enhanced odor control mode. In various embodiments, the different levels of operation of the fan may include different speeds and/or different on times for the fan. For example, in some embodiments, the first level may include a first speed and the second level may include a second speed greater than the first speed. As another example, in additional embodiments, the first level may include a first on time and the second level may include a second on time longer than the first on time. The enhanced odor control mode may also be time-limited, e.g., some embodiments may include a time out setting, such as between about twenty-four hours and about forty-eight hours, after which the enhanced odor control mode is automatically terminated or suspended.

The second level greater than the first level may provide an increased air flow into and/or within the food storage chamber, such as additional air circulation within the food storage chamber to dissipate odors therein and/or additional air flow over, across, and/or through an air filter such as air filter 204 described above to remove or reduce odors via filtration. It is to be understood that “odors” as described herein refers to substances such as volatile organic compounds (VOCs) and/or other vapors, gasses, etc., which may be present in the food storage chamber in sufficiently high concentration that a user-perceptible odor is created. The “user” in the term “user-perceptible” odor is used with reference to an average adult human with no impairments to their sense of smell, e.g., a “user-perceptible” odor includes any odor which such user would readily detect or perceive when accessing the refrigerator appliance 100, such as standing in front of the refrigerator appliance 100 within arm's reach (about twenty four inches to about thirty inches or less) of the fresh food chamber 122 while at least one door 128 is open. Thus, the second level greater than the first level may help to dissipate such substances and/or increase the rate at which such substances are removed from the air by the air filter. For example, the increased fan level may also provide increased cooling of the food storage chamber. Such cooling may increase the adsorption rate of odors, e.g., VOCs, by the air filter in embodiments where an air filter is included.

In at least some embodiments, the operation level of the fan, e.g., the rotational speed and/or on time, may impact the level of cooling, e.g., the amount of cooled air C (FIG. 4), provided to the food storage chamber, such as in embodiments where the fan is an evaporator fan, such as fan 74 of FIG. 4. Thus, in some embodiments, operating the fan at the second level greater than the first level during the enhanced odor control mode may also result in lowering the temperature in the food storage chamber. For example, the temperature in the food storage chamber may be lowered during the enhanced odor control mode such that the temperature is below the desired level, e.g., is below the set temperature. In some embodiments, exemplary methods according to the present disclosure may further include, after operating the fan at the second level, measuring a temperature within the food storage chamber, e.g., an ambient temperature of the atmosphere within the food storage chamber. Such embodiments may further include comparing the measured temperature with the set temperature, and activating a heat source when the measured temperature is less than the set temperature. Additional embodiments may include lowering the set temperature, as well as or instead of activating the heat source, when the measured temperature is less than the set temperature. For example, the measurement and comparison of the temperature may be performed when the enhanced odor control mode has been active for at least a predetermined minimum time and/or the measurement and comparison of the temperature may be performed when the second level exceeds the first level by at least a predetermined threshold, e.g., a minimum percentage.

Any suitable heat source may be activated in such embodiments. For example, the heat source may include a light, such as a light which may be installed in the food storage chamber for illumination thereof, e.g., in response to a door opening. As such, the heat source may include a component which is already provided in the base design of the refrigerator appliance, such as the light or other standard refrigerator component, e.g., the exemplary method may, in such embodiments, be performed without requiring additional or specialized components dedicated to only the enhanced odor control mode. In additional embodiments, the heat source may also or instead include a heater, such as a resistance heating element or other electrical heater.

In embodiments where the fan is a fan of a sealed cooling system, such as the evaporator fan 74, and in instances when the enhanced odor control mode is activated or initiated while the cooling system, e.g., system 60, is not running, such as the compressor 64 is not motivating the refrigerant through the system 60, and in particular through the evaporator 70 thereof, then air that is introduced into and/or circulated within the food storage chamber while operating the fan at the second level greater than the first level may be at or about the same temperature as the remainder of the food storage chamber. Thus, when the cooling system is not running at the time that the enhanced odor control mode is initiated, the odor control mode is less likely to result in overcooling, such that the heat source may not be activated in such circumstances and/or the enhanced odor control mode may not be time-limited.

In some embodiments, the enhanced odor control mode may be manually activated, e.g., by a user input. For example, one or more exemplary methods according to the present disclosure may include, while operating the fan at the first level during the normal mode, receiving a user input, wherein the enhanced odor control mode is initiated in response to the user input.

As mentioned above, the enhanced odor control mode may provide odor reduction by dissipating odorous substances within the food storage chamber due to increased air circulation therein. Also as mentioned above, the enhanced odor control mode may further provide air filtration to reduce odors. For example, the refrigerator appliance may include an air filter proximate to the fan, e.g., whereby the air filter is within the flow path of air motivated by the fan, e.g., whereby the air filter is upstream or downstream of the fan, such as immediately upstream or immediately downstream of the fan, or separated from the fan only by an internal wall of the food storage chamber and the grille 200 in the wall. In such embodiments, the air filter and the fan may be positioned upstream of the food storage chamber with respect to an air flow path within the refrigerator appliance, whereby operating the fan includes and/or results in urging air across and/or through the air filter and into the food storage chamber, such as through a grille 200 (FIGS. 5 through 7) with the fan and the air filter positioned at, e.g., generally aligned with, the grille. In at least some embodiments, the air filter may be positioned within the food storage chamber (e.g., as illustrated in FIGS. 6 and 7) while the fan may be positioned on the opposite side of the grille 200 and/or on the opposite side of an internal wall such as back wall 123 with the fan positioned proximate the grille 200 and aligned with the grille 200 such that, when activated, the fan urges air, e.g., cooled air C, through the grille 200 and then through the air filter 204. In additional embodiments, the relative positions of the fan and air filter 204 may be reversed and/or the operation of the fan may be reversed, e.g., such that the air filter 204 is on the suction side (upstream) of the fan or on the pressure side (downstream) of the fan. Thus, in various embodiments, the fan may urge air across the air filter in various directions and/or through the air filter in various directions, e.g., “urging” the air may include sucking the air or blowing the air and/or the direction of air flow relative to the air filter may vary by locating the fan in various positions.

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.

Claims

1. A method of operating a refrigerator appliance, the refrigerator appliance comprising a cabinet defining a food storage chamber therein, the method comprising:

operating a fan of the refrigerator appliance at a first level during a normal mode, the first level determined by a call for cooling based on a set temperature for the food storage chamber; and

operating the fan at a second level greater than the first level during an enhanced odor control mode.

2. The method of claim 1, further comprising, after operating the fan at the second level, measuring a temperature within the food storage chamber, comparing the measured temperature with the set temperature, and activating a heat source when the measured temperature is less than the set temperature.

3. The method of claim 2, wherein the heat source comprises a light.

4. The method of claim 2, wherein the heat source comprises a heater.

5. The method of claim 1, further comprising, while operating the fan at the first level during the normal mode, receiving a user input, wherein the enhanced odor control mode is initiated in response to the user input.

6. The method of claim 1, wherein the fan is an evaporator fan.

7. The method of claim 1, wherein the refrigerator appliance further comprises an air filter proximate to the fan, the air filter and the fan upstream of the food storage chamber with respect to an air flow path within the refrigerator appliance, whereby operating the fan comprises urging air across the air filter and into the food storage chamber.

8. The method of claim 1, wherein the first level comprises a first speed and the second level comprises a second speed greater than the first speed.

9. The method of claim 1, wherein the first level comprises a first on time and the second level comprises a second on time longer than the first on time.

10. A refrigerator appliance, comprising:

a cabinet defining a food storage chamber therein;

a fan; and

a controller, wherein the controller is configured for: operating the fan at a first level during a normal mode, the first level determined by a call for cooling based on a set temperature for the food storage chamber; and operating the fan at a second level greater than the first level during an enhanced odor control mode.

11. The refrigerator appliance of claim 10, wherein the controller is further configured for, after operating the fan at the second level, measuring a temperature within the food storage chamber, comparing the measured temperature with the set temperature, and activating a heat source when the measured temperature is less than the set temperature.

12. The refrigerator appliance of claim 11, wherein the heat source comprises a light.

13. The refrigerator appliance of claim 11, wherein the heat source comprises a heater.

14. The refrigerator appliance of claim 10, wherein the controller is further configured for, while operating the fan at the first level during the normal mode, receiving a user input, and is further configured for initiating the enhanced odor control mode in response to the user input.

15. The refrigerator appliance of claim 10, wherein the fan is an evaporator fan.

16. The refrigerator appliance of claim 10, further comprising an air filter proximate to the fan, the air filter and the fan upstream of the food storage chamber with respect to an air flow path within the refrigerator appliance, whereby operating the fan comprises urging air across the air filter and into the food storage chamber.

17. The refrigerator appliance of claim 10, wherein the first level comprises a first speed and the second level comprises a second speed greater than the first speed.

18. The refrigerator appliance of claim 10, wherein the first level comprises a first on time and the second level comprises a second on time longer than the first on time.