Patent Publication Number: US-9896321-B2

Title: Auto water dispenser cutoff

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application of U.S. application Ser. No. 13/765,766, filed, Feb. 13, 2013, the entire disclosure of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present application relates generally to refrigeration appliances, and in particular to dispensing units associated with refrigeration appliances. 
     BACKGROUND OF THE INVENTION 
     Modern refrigeration appliances, such as household refrigerators for example, often include as one of their features a dispenser for dispensing content, the content typically being water and/or ice. Frequently, the dispenser is located within a recess in the exterior surface of a door of the appliance. The refrigeration appliance can take any one of a number of forms. For example, the refrigeration appliance can have freezer and fresh food compartments that are arranged side-by-side, the freezer compartment can be located above the fresh food compartment, or the freezer can be located below the fresh food compartment. In any case, separate doors can be provided for the freezer and fresh food compartments and a dispenser can be located within the recess in the exterior of at least one of the doors. 
     Conventionally, the dispenser can include at least an outlet for dispensing water and an outlet for dispensing ice. Associated with the water dispensing outlet can be a lever in the form of a cradle or other actuating device that is pivotally attached to the dispenser. In addition to a lever, the actuating device could also be used with other types of vessel detection such as optical, visual, or ultrasonic, etc. When water is to be dispensed, a receiver vessel, usually in the form of a beverage glass, is pressed against the lever thereby operating a switch or sensor so as to complete an electrical circuit between a source of electrical power and a solenoid-operated valve connected to a source of water. The completion of the electrical circuit opens the solenoid-operated valve (or even other types of valves, such as motor actuated valves, etc.) permitting the water to flow from the source of water to the water dispensing outlet. 
     BRIEF SUMMARY OF THE INVENTION 
     The following presents a simplified summary of the invention in order to provide a basic understanding of some example aspects of the invention. This summary is not an extensive overview of the invention. Moreover, this summary is not intended to identify critical elements of the invention nor delineate the scope of the invention. The sole purpose of the summary is to present some concepts of the invention in simplified form as a prelude to the more detailed description that is presented later. 
     In accordance with one aspect of the present invention, a refrigerator comprises a refrigerated compartment and a door to open and close at least a portion of the refrigerated compartment. A dispenser is positioned on the door that is configured to dispense content into a receiver vessel. The dispenser comprises a control unit, an actuation system controlled by the control unit, and a dispensing outlet through which the content flows from the dispenser and into the receiver vessel. The dispenser further comprises a trough located below the dispensing outlet for collecting overflow content from at least one of the receiver vessel and the dispensing outlet. The dispenser further comprises a sensor coupled to the trough and in electrical communication with the control unit. The sensor is configured to detect overflow content contained within the trough. 
     In accordance with another aspect of the present invention, a method for controlling the dispensing of content from a dispenser, comprising the steps of dispensing content into a receiver vessel, and measuring a sensed value in a trough located below the dispensing outlet during the dispensing of content. The sensed value representing an overflow content level contained within the trough. The method further comprises the steps of comparing the sensed value to a reference value, and terminating the dispensing of content from the dispensing outlet when the sensed value differs from the reference value by a predetermined amount. 
     It is to be understood that both the foregoing general description and the following detailed description present example and explanatory embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various example embodiments of the invention, and together with the description, serve to explain the principles and operations of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other aspects of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic front elevation view of a refrigeration appliance illustrating one example dispensing unit; 
         FIG. 2  is a detailed view of the example dispensing unit; 
         FIG. 3  is a schematic illustration of an example dispenser trough with a plurality of capacitive sensors coupled to the trough; and 
         FIG. 4  is a schematic illustration of another example dispenser trough with a pressure transducer coupled to the trough. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Example embodiments that incorporate one or more aspects of the present application are described and illustrated in the drawings. These illustrated examples are not intended to be a limitation on the present application. For example, one or more aspects of the present application can be utilized in other embodiments and even other types of devices. Moreover, certain terminology is used herein for convenience only and is not to be taken as a limitation on the present application. Still further, in the drawings, the same reference numerals are employed for designating the same elements. 
     Turning to the shown example of  FIG. 1 , a refrigeration appliance in the form of a refrigerator  10  is illustrated as a side-by-side refrigerator with freezer and fresh food compartments. Conventional refrigeration appliances, such as domestic refrigerators, typically have both a fresh food compartment and a freezer compartment or section. The fresh food compartment is where food items such as fruits, vegetables, and beverages are stored and the freezer compartment is where food items that are to be kept in a frozen condition are stored. The refrigerators are provided with a refrigeration system that maintains the fresh food compartment at temperatures above 0° C. and the freezer compartments at temperatures below 0° C. 
     The arrangement of the fresh food and freezer compartments with respect to one another in such refrigerators vary. For example, in some cases, the freezer compartment is located above the fresh food compartment (i.e., a top mount refrigerator), and in other cases the freezer compartment is located below the fresh food compartment (i.e. a bottom mount refrigerator). Additionally, many modern refrigerators have their freezer compartments and fresh food compartments arranged in a side-by-side relationship. Whatever arrangement of the freezer compartment and the fresh food compartment is employed, typically, separate access doors are provided for the compartments so that either compartment may be accessed without exposing the other compartment to the ambient air. For example, a door  12  provides access to the freezer compartment, and a door  14  provides access to the fresh food compartment of the refrigerator. Both of the doors are pivotally coupled to a cabinet of the refrigerator  10  to restrict and grant access to the fresh food and freezer compartments. 
     Located generally centrally at the surface or exterior of the door  12  is an example dispenser indicated generally at  30 . It is understood that dispenser  30  could also be located at various locations on the refrigerator door or even inside the refrigerator. As can best be seen in  FIG. 1 , the dispenser  30  is located in a recess  16  in the door  12 . The recess comprises side walls or surfaces  18  and  20  that are opposite one another, a bottom or lower wall or surface  22 , an upper or top wall or surface  24  and a back or rear wall or surface  26 . A water dispensing outlet  32  for dispensing cold water and an ice dispensing outlet  34  for dispensing ice are located at the upper surface  24  of the recess  16 . In the shown embodiment of  FIG. 1 , the dispenser  30  can include a single dispensing outlet for the water  32  and ice  34  arranged so as to substantially coincide with one another at the upper surface  24  of the recess  16 . However, in an alternative embodiment (not shown), a single dispensing outlet for water  32  and a single dispensing outlet for ice  34  can be arranged so as to be spaced apart from one another at the upper surface  24  of the recess  16  across the width of the access door  12  and not coincide with each other. The bottom surface  22  of the recess  16  can include a trough and/or drain (see  FIG. 2 ) for draining away excess water from the water dispensing outlet  32  and/or water formed from melting ice from the ice dispensing outlet  34  that comes to rest on the bottom surface  22 . 
     Turning to  FIG. 2 , at least one water line  36  extends from the water dispensing outlet  32  to a source of the water. The source of water can be, for example, a water reservoir connected to the household water supply system or the household water supply itself or such other sources as are familiar to those having ordinary skill in the art. A solenoid-operated valve  50  can be located in fluid communication with the water line  36  and can be controlled by control unit  54  that can include a microprocessor  52 , for example as discussed below. Though described as a solenoid-operated valve  50 , other types of valves can be used, such as motor actuated valves or the like. Additionally, at least one water filter can be located in fluid communication with the at least one water line  36  to purify the incoming water. 
     Keeping with the shown example of  FIG. 2 , a trough  60  can be located below the water dispensing outlet  32  and the ice dispensing outlet  34 . The trough  60  collects overflow content that is typically spilled or overflowed water or ice from the water dispensing outlet  32 , ice dispensing outlet  34 , and/or receiver vessel  42 . This overflow content is referred to herein as residual content  62 . The trough  60  can be part of the bottom surface  22  that supports the receiver vessel  42 , or even below the bottom surface  22 . The trough  60  can have a geometry configured to capture and retain the residual content  62 . In one example, the trough  60  can have a generally concave geometry so that the residual content  62  collected by the trough  60  pools generally towards a vertex or minimum  64  of the trough  60 . The geometry of the trough  60  can also be a wedge, a “V”, a “U”, a “W”, or a number of other designs with one or more local minimums. 
     The ice dispensing outlet  34  comprises essentially an opening in the upper surface  24  of the recess  16 . The opening is in communication with a source of ice such as, for example, the ice storage bin of an ice making unit (not shown) located in the fresh food or freezer compartment of the refrigerator. Typically, as is familiar to those of ordinary skill in the art, the ice is delivered from the ice storage bin to the ice dispensing outlet  34  by an auger which upon activation rotates so as to drive the ice from the storage bin to the ice dispensing outlet  34 . Activation of the auger can be accomplished by the control unit  54  that also controls the operation of a solenoid-operated valve  50  located in the water line  36 , or by other control structure. 
     At least one switch  38  can be electronically coupled to the control unit  54  and be configured to dispense either or both of water from the water dispensing outlet  32  and ice from the ice dispensing outlet  34 . Alternatively, separate switches (not shown) can be provided for each of the water dispensing outlet  32  and the ice dispensing outlet  34 . The at least one switch  38  can be a contact-style switch, or can alternatively be non-contact style switch, including other types of vessel detection such as optical, visual, or ultrasonic, etc. In addition or alternatively, at least these functions can be controlled by the microprocessor  52 , which can be appropriately programmed using information that is input by a user to a user interface  40  that is electrically connected to the microprocessor  52 . Thus, when a receiver vessel  42  such as a glass is inserted within the recess  16  and the switch  38  is activated, water and/or ice can be dispensed on-demand into the receiver vessel  42 . 
     Operation of the dispenser  30  can be controlled by a control unit  54 . The control unit  54  can be comprised of various components, including the microprocessor  52  and/or an analog to digital converter (ADC)  56 . The microprocessor  52  can be programmed in various ways to accept user inputs from a user interface  40 . Additionally, the microprocessor  52  can receive signals from the ADC  56  and/or a sensor  58  to determine the amount of residual content  62  contained within the trough  60 . Sensor  58  could include electrodes connected directly to a microcontroller, such that two separate microcontrollers could be used ( 52  and  58 ), or that the microcontroller connected directly to the electrodes (sensor  58 ) could serve both functions thus combining  52  and  58  into one. Thus, it is contemplated that the control unit  54  could be a main control unit of the appliance, or even a sub-control unit. Utilizing the residual content  62  level information with the user input data, the microprocessor  52  can determine when to dispense content and/or terminate the dispensing of content. The microprocessor  52  outputs a signal to control the solenoid-operated valves  50  of the dispenser  30 . While the various examples discussed herein include a digital microcontroller, it is contemplated that full analog, full digital, or hybrid systems can be used. In one example, the ADC  56  can receive analog signals from the sensor  58  that detects the residual content  62  level in the trough  60 . The ADC  56  can receive analog inputs (e.g., voltage, current, capacitance, and/or resistance), and convert the inputs into a corresponding digital output that is transmitted to the microprocessor  52 . Still, the sensor  58  could directly output digital signals. 
     The sensor  58  can be configured to detect overflow content in the trough  60  in various ways. In one example shown in  FIG. 3 , the sensor  58 A comprises at least one capacitive sensor  70 , such as a plurality of capacitive sensors  72 , coupled to the trough  60 A. The trough  60 A can be made from a dielectric material, such as plastic, glass, porcelain, rubber, or any other material that is a relatively poor conductor of electricity. When the trough  60 A is made from a dielectric material, residual content  76  can influence the capacitance sensed by the capacitive sensor  70  or sensors  72 . Generally, dielectric constants of liquids are greater than that of air; for example, the dielectric constant of water is 80 times that of air. This property allows for a measureable change in sensed capacitance as the level of residual content  76  changes within the trough  60 A. 
     The capacitive sensor  70  or sensors  72  generally have a limited sensing range. When the capacitive sensor  70  or sensors  72  are coupled to the trough  60 A at a fixed position and the residual content  76  level has not reached the sensing range of the capacitive sensor  70  or sensors  72 , a sensed capacitance will change little, if at all. When the residual content  76  level reaches the sensing range of the capacitive sensor  70  or sensors  72 , a dielectric effect of the residual content  76  changes a sensed capacitance detected by the capacitive sensor  70  or sensors  72 . Thus, the level of residual content  76  within the trough  60 A can be approximated by determining when the capacitive sensor  70  or sensors  72  have a change in sensed capacitance due to the level of residual content  76  rising in the trough  60 A to within the sensing range of the capacitive sensor  70  or sensors  72 . 
     In one example embodiment, only one capacitive sensor  70  is employed. This capacitive sensor  70  can be coupled to the trough  60 A at a fixed position that is a known distance with respect to another fixed element, such as a vertex or local minimum  74  of the trough  60 A. When the residual content  76  level rises to the fixed position of the capacitive sensor  70 , a sensed capacitance increases. The capacitive sensor  70 , in electrical communication with the control unit  54 , communicates a signal representing the sensed capacitance to the control unit  54 . Thus, because the distance between the capacitive sensor  70  and a fixed element such as the vertex or minimum  74  of the trough  60 A can be known, the control unit  54  can accurately estimate the depth of the residual content  76 . 
     The control unit  54  for a single capacitive sensor  70  implementation can determine the content depth and/or if an overflow condition exists in various manners. In one embodiment, the control unit  54  can determine that an overflow condition exists when the sensed capacitance at the capacitive sensor  70  changes. Any change in the sensed capacitance indicates that the residual content  76  level has reached the sensing range of the capacitive sensor  70 . 
     In another embodiment of the control unit  54  for a single capacitive sensor  70  implementation, the control unit  54  can compare the sensed capacitance to a reference capacitance, and determine that an overflow condition exists when the sensed capacitance approaches or exceeds the reference capacitance. This reference capacitance can be predetermined. In one example, the predetermined reference capacitance can be static, or in another example, the predetermined reference capacitance can be variable. For example, the control unit  54  can be configured to determine a variable reference capacitance via a signal from the capacitive sensor  70  before the dispenser  30  is activated, which can be stored by the control unit  54  as the reference capacitance. Then, while the dispenser  30  is dispensing content, the capacitive sensor  70  measures the sensed capacitance at least once, such as two or more different times, and communicates signals representing the sensed capacitance(s) to the control unit  54 . The control unit  54  can then compare the sensed capacitance(s) to the stored reference capacitance. If the sensed capacitance(s) is/are different than the reference capacitance by a predetermined amount, then the control unit  54  will determine that an overflow condition exists. The foregoing examples contemplate comparing capacitances greater and/or lower than a reference capacitance. These are just a few examples of how the control unit  54  can determine that an overflow condition exists in a single capacitive sensor implementation of the sensor  58 . 
     The control unit  54  can further be configured to output a signal to the solenoid-operated valves  50  that terminates the dispensing of content when an overflow condition exists and/or prevents the dispensing of content when the trough  60 A is determined to be full. The control unit  54  can determine that an overflow condition exists according to any of the previous examples, such as when the sensed capacitance equals or exceeds the static reference capacitance or a predetermined full-trough capacitance limit. When the control unit  54  determines that the trough  60 A is no longer full, such as when the sensed capacitance falls below the reference capacitance or full-trough limit, and/or when an overflow condition no longer exists, the dispensing of content can resume. 
     In another example shown in  FIG. 3 , a plurality of capacitive sensors  72  can be employed. The capacitive sensors  72  can be coupled to the trough  60 A in numerous arrangements, such as various linear or circular patterns along one, two, or three axes. In one example, the capacitive sensors  72  can be arranged between points near a vertex or minimum  74  of the trough  60 A and near the top  75  of the trough  60 A. When a plurality of capacitive sensors  72  are employed, sensed capacitance measurements can be taken at multiple discrete locations, allowing for greater resolution in determining the level of residual content  76  within the trough  60 A. The capacitive sensors  72 , in electrical communication with the control unit  54 , communicate one or more signals representing the sensed capacitance(s) of the various capacitive sensors  72  to the control unit  54 . As before, because the distance between each capacitive sensor  72  and a fixed element such as the vertex or minimum  74  of the trough  60 A can be known, the control unit  54  can accurately estimate the depth of the residual content  76  contained within the trough  60 A. It is understood that the control unit  54  can utilize the plurality of sensed capacitances from the capacitive sensors  72  directly to determine whether an overflow condition exists, or can utilize the plurality of sensed capacitances indirectly by converting or translating them into a depth or height of the residual content  76  within the trough  60 A. 
     The control unit  54  for an implementation of a plurality of capacitive sensors  72  can determine the content depth and/or if an overflow condition exists in various manners. In one example embodiment, the control unit  54  can determine that an overflow condition exists when the sensed capacitance exceeds a static reference capacitance by a predetermined amount. In this example, the control unit  54  can estimate the depth of the residual content  76  according to the capacitances measured by the capacitive sensors  72 , but an overflow condition will not be generated until the measured capacitance approaches or exceeds the static reference capacitance by a predetermined amount. 
     In another example embodiment, a moving reference capacitance can be used by the microprocessor  52 . This can accommodate situations where residual content  76  is already present in the trough  60 A. The amount of residual content  76  in the trough can be measured prior to dispensing content, or if no measurement is taken prior to the dispensing of content, the last known reference capacitance stored by the control unit  54  can be used. While the dispenser  30  is dispensing content, the plurality of capacitive sensors  72  can measure the sensed capacitance at least once, such as two or more different times, and transmits signals representing the sensed capacitances to the control unit  54 . The control unit  54  compares the sensed capacitances to the variable reference capacitance value. The difference between the sensed capacitances and the variable reference capacitance can be compared to determine if the change indicates the residual content  76  is increasing, and if so, the control unit  54  can determine that an overflow condition exists. 
     In another embodiment employing a plurality of capacitive sensors  72 , a determination can be made of the rate of change of the residual content  76  level over time. The rate of change of the residual content  76  can be determined based upon a determination of the rate of change of the sensed depth of the residual content  76 , or a rate of change of the sensed capacitances. The rate of change determination can be used with a static or variable reference value. While the dispenser  30  is dispensing content, the capacitive sensors  72  measure the sensed capacitance at least once, such as two or more different times, and transmit signals representing the sensed capacitances to the control unit  54 . Using the two or more sensed values, the microprocessor  52  can determine a rate of change of the capacitances over time. If a sensed rate of change exceeds the reference value by a predetermined amount, the microprocessor  52  will determine that an overflow condition exists and will output a signal to the solenoid operated valves  50  that terminates the dispensing of content. In addition or alternatively, the control unit  54  can compare the sensed capacitances to the variable reference capacitance. The difference between the sensed capacitances and the variable reference capacitance represents the change in residual content  76  level over time. If the change indicates the residual content  76  is increasing, the control unit  54  can determine that an overflow condition exists. 
     In another embodiment employing the plurality of capacitive sensors  72 , the control unit  54  can be configured to sum the capacitances of some or all of the capacitive sensors  72  instead of using data from each individual capacitive sensor. In this example, the control unit  54  can receive signals representing the sensed capacitances of each of the plurality of capacitive sensors  72 , and compare the summation of the sensed capacitances to either a static reference capacitance or a variable reference capacitance. 
     In another embodiment, the plurality of capacitive sensors  72  can be further configured to determine that the trough  60 A is full in various manners. In one embodiment employing a static reference capacitance, the control unit  54  can determine that the trough  60 A is full when the sensed capacitance differs from the static reference capacitance by a predetermined amount. In an embodiment employing a variable reference capacitance, the control unit  54  can determine that the trough  60 A is full when either the variable reference capacitance or the sensed capacitance differs from a full-trough capacitance by a predetermined amount. The variable reference capacitance can generally be determined after the dispensing of content has been terminated and before the dispensing of content has resumed. After the dispensing of content has been terminated, the depth of residual content  76  contained within the trough  60 A can potentially be at or above the sensing range of the capacitive sensor nearest the top  75  of the trough  60 A. The result is the variable reference capacitance being stored can equal the maximum detectable capacitance, making it difficult to generate future overflow conditions. To reduce this outcome, a full-trough capacitance can be predetermined and stored in the control unit  54 . When the variable reference capacitance approaches, equals, or exceeds the predetermined full-trough capacitance, the control unit  54  can determine the trough  60 A to be full. Thus, prior to the dispensing of content, the variable reference capacitance can represent at least one of an instant residual content level contained within a trough and a full-trough value. 
     As before, the control unit  54  can further be configured to output a signal to the solenoid-operated valves  50  that terminates the dispensing of content when an overflow condition exists and/or prevents the dispensing of content when the trough  60 A is determined to be full. When the control unit  54  determines that an overflow condition no longer exists, such as when the variable reference capacitance falls below the full-trough capacitance limit and/or the sensed capacitance is less than the static reference capacitance, the dispensing of content can resume. The various embodiments of the control unit  54  are not intended to be an exhaustive list of possible implementations. Furthermore, it is contemplated that the control unit  54  can combine two or more of the embodiments described herein. 
     The user can be alerted that the trough  60 A is full by an indicator light, an audible alarm, or other various methods. The alert can be displayed on the user interface  40  or dispenser  30 , for example, or on the main control of the appliance. This will prompt the user to either empty the trough  60 A, or wait until a portion of the residual content  76  has evaporated. The capacitive sensor  70  or sensors  72  can periodically measure capacitances and communicate signals representing the capacitances to the control unit  54 . The control unit  54  can then compare these measured capacitances to either a static reference capacitance and/or a predetermined full-trough capacitance limit to determine whether the trough  60 A is still full. 
     Turning now to  FIG. 4 , another example sensor  58 B,  58 C embodiment is shown. The sensor  58 B,  58 C can be a fluid pressure transducer  80 ,  80 B coupled to a trough  60 B that can be utilized to detect the fluid pressure of residual content  86  contained within the trough  60 B. The pressure transducer  80 ,  80 B is coupled to the trough  60 B by at least one capillary tube  82 , which is in fluid communication with the trough  60 B at a hole  84  located at a predetermined location, such as about a vertex or a local minimum  88  of the trough  60 B. The pressure transducer  80 ,  80 B is in fluid communication with the hole  84  via the capillary tube  82 ,  82 B and is in electrical communication with the control unit  54 . It is understood that the fluid pressure sensed by the pressure transducer can be either a liquid pressure, as shown by sensor  58 B, or can be a gas pressure as shown by sensor  58 C. One or more of the sensors  58 B,  58 C can be used alone or together. For brevity, it is understood that the discussion herein of the pressure transducer can include either of the liquid or gas pressure transducer  80 ,  80 B embodiments even if only one is mentioned. 
     The trough  60 B, located below the dispensing outlet for water  32  and/or the dispensing outlet for ice  34 , can have a generally concave geometry so that content collected by the trough  60 B pools generally towards a vertex or a minimum  88  of the trough  60 B. The geometry of the trough  60 B can also be a wedge, a “V”, a “U”, a “W”, or a number of other designs with one or more one local minimum. As shown, the hole  84  is located generally at or near the vertex or minimum  88  of the trough  60 B. One end of the capillary tube  82  is attached to the hole  84  and the other end of the capillary tube  82  is attached to the pressure transducer  80 ,  80 B. While this embodiment describes utilizing one pressure transducer  80 ,  80 B, one capillary tube  82 , and one hole  84 , it can be appreciated that the design can include multiple pressure transducers, each with one or more corresponding capillary tube(s) and hole(s) and coupled to the trough  60 B at predetermined locations. 
     Residual content  86  contained within the trough  60 B enters the capillary tube  82  and travels to the pressure transducer  80 ,  80 B, where the residual content  86  exerts a fluid pressure against the pressure transducer  80 ,  80 B. As the residual content  86  level rises, the fluid pressure exerted by the residual content  86  against the pressure transducer  80 ,  80 B increases. As noted, the fluid pressure sensed by the pressure transducer can be either a liquid pressure  58 B or a gaseous pressure  58 C. Depending on the type of pressure transducer, it may be mounted below the fluid level (see pressure transducer  80 ) so that it has liquid contact (e.g., liquid contact), or it may be mounted above the fluid level (see pressure transducer  80 B) so that the liquid is not in direct contact with the sensor, but the fluid height would compress a gas column  83  (e.g., air or other gas) which is in contact with the pressure transducer  80 B. 
     In one example, where fluid pressure increases linearly, the controlling equation for measuring pressure is P=pgh, where ρ is the density of the residual content  86  contained within the trough  60 B, g is gravity, and h is the height or level of the residual content  86  contained within the trough  60 B. The height h can be measured with respect to a fixed point, such as the location of the hole  84  (e.g., the vertex  88  or another point). The density of the residual content  86  (e.g., water) and gravity are generally constant, resulting in the pressure being a function of only the level of residual content  86  contained within the trough  60 B. Therefore, the residual content  86  level (i.e., height h) can be accurately predicted based upon the pressure detected by the pressure transducer  80 ,  80 B. The output of the pressure transducer  80 ,  80 B can be of various types, including voltage, current, or a number of other outputs. In one example, the output of the pressure transducer  80 ,  80 B is an analog voltage that can increase as the pressure exerted on the pressure transducer  80 ,  80 B increases. The analog voltage output is transmitted to the control unit  54 . Still, various analog or digital signals can be output by the pressure transducer  80 ,  80 B. It is contemplated that the control unit  54  and/or pressure transducer  80 ,  80 B can compensate for such as local temperature, barometric or meteorological characteristics of where the refrigerator is located, and make appropriate adjustments, especially where the pressure of a compressed gas column  83  (e.g., air or other gas) is used. 
     The control unit  54  can determine that an overflow condition exists in various ways, including when a sensed pressure exceeds a reference pressure by a predetermined amount. In one embodiment, the reference pressure can be a fixed reference pressure. When the dispenser  30  is dispensing content, the pressure transducer  80 ,  80 B can be configured to measure the pressure of the residual content  86  at least one, such as two or more different times, and communicate signals representing the sensed pressures to the control unit  54 . The microprocessor  52  receives signals representing the sensed pressures and compares each sensed pressure to the fixed reference pressure. If a sensed pressure differs (e.g., greater or lesser) from the fixed reference pressure by a predetermined amount, the microprocessor  52  will determine that an overflow condition exists and will output a signal to the solenoid operated valve  50  that terminates the dispensing of content. 
     In another example embodiment, a moving reference pressure can be used by the microprocessor  52 . This can accommodate situations where residual content  86  is already present in the trough  60 B. The amount of residual content  86  in the trough can be measured prior to dispensing content, or if no measurement is taken prior to the dispensing of content, the last known reference pressure stored by the control unit  54  can be used. While the dispenser  30  is dispensing content, the pressure transducer  80 ,  80 B measures the sensed pressure at least once, such as two or more different times, and transmits signals representing the sensed fluid pressure to the control unit  54 . The control unit  54  compares the sensed pressures to the variable reference pressure value. The difference between the sensed pressures and the variable reference pressure can be compared to determine if the change indicates the residual content  86  is increasing, and if so, the control unit  54  can determine that an overflow condition exists and will output a signal to the solenoid operated valves  50  that terminates the dispensing of content. 
     In another example, a determination can be made of the rate of change of the residual content  76  level over time, and an overflow condition can be generated when a rate change in pressure over time is greater than a predetermined amount. The rate of change of the residual content  86  can be determined based upon a determination of the rate of change of the sensed depth of the residual content  86 , or a rate of change of the sensed pressure. In order to determine whether there is a change in pressure, first a reference pressure can be measured (or the last known reference pressure stored by the control unit  54  can be used) before the dispenser  30  begins dispensing content. The reference pressure is communicated to the control unit  54 , and the value representing the reference pressure is stored in the microprocessor. This can allow the microprocessor  52  to accurately predict the residual content  86  level when the dispenser  30  is not dispensing content. When the dispenser  30  begins dispensing content, the pressure transducer  80 ,  80 B can measure the sensed pressure at two or more different times and communicate signals representing the sensed pressures to the control unit  54 . The microprocessor  52  then compares the sensed pressures to the previously stored moving reference pressure. Using the two or more sensed values, the microprocessor  52  can determine a rate of change of the pressure over time. If a sensed rate of change exceeds the reference value by a predetermined amount, the microprocessor  52  will determine that an overflow condition exists and will output a signal to the solenoid operated valves  50  that terminates the dispensing of content. In addition or alternatively, if a sensed pressure exceeds the moving reference pressure by a predetermined amount, the microprocessor  52  will determine that an overflow condition exists and will output a signal to the solenoid operated valves  50  that terminates the dispensing of content. 
     The microprocessor  52  can further be configured to prevent the dispensing of content when the trough  60 B is determined to be full. When a sensed pressure or a moving reference pressure equals or exceeds a predetermined maximum fill pressure, the microprocessor  52  can determine that the trough  60 B is full prevent the dispensing of content. 
     A user can be alerted that the trough  60 B is full by an indicator light, an audible alarm, or other various methods. The alert can be displayed on the user interface  40  or dispenser  30 , for example, or on the main control of the appliance. This will prompt the user to either empty the trough  60 B, or wait until at least a portion of the residual content  86  has evaporated. The pressure transducer  80 ,  80 B can periodically measure the pressure so that the microprocessor  52  can compare this measured pressure to the maximum fill pressure in order to determine when the trough  60 B is no longer full. 
     When the control unit  54  determines that the trough  60 B is no longer full, such as when the sensed pressure or moving reference pressure falls below the predetermined maximum fill pressure, the dispensing of content can resume. It is also contemplated that the control unit  54  can alter, such as increase or reduce, the flow rate of fluid provided by the dispenser. For example, if the control unit  54  determines that the amount of residual content in the trough is increasing but has not yet reached a maximum value, the control unit  54  could reduce the flow rate of the dispenser to a lower but non-zero amount. Once it is determined that the residual content has reached a maximum value for the trough, the control unit  54  can then completely terminate dispensing. Similarly, the flow rate of the dispenser could be stored in memory, and if the amount of residual content in the trough has not reduced sufficiently, a subsequent filling operation could utilize the previous low-flow filling rate. Conversely, if the trough has been reduced or emptied between filling operations, the flow rate of the dispenser could be increased. 
     It is contemplated that, in relation to sensed values by the sensor, use of the word “exceeds” (and similar words/phrases) refers to sensed values that differ to greater or lesser amount as compared to a known value. Thus, a sensed value can exceed a known value by being greater than or less than the known value by a certain amount. 
     The invention has been described with reference to the example embodiments described above. Modifications and alterations will occur to others upon a reading and understanding of this specification. Examples embodiments incorporating one or more aspects of the invention are intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.