Abstract:
A refrigerated appliance includes a power interrupt system for detecting an out-of-range temperature condition in a fresh food or freezer compartment after a power interruption. The power interrupt system includes a central processor including a memory storage module and a plurality of temperature sensors. In operation, the power interrupt system compares sensed temperature values with stored temperature variables. If, after a power interruption, a compartment temperature exceeds a stored temperature variable by a defined amount, an over-temperature flag is triggered. Preferably, a display unit flashes an indication of the highest temperature reached by each compartment intermittently with the current compartment temperatures and an indication that a power interruption has occured. In this manner, a consumer can make an informed determination whether food stored within the appliance has been exposed to temperatures high enough to cause spoilage.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of refrigerated appliances and, more particularly, to a refrigerated appliance having a system for detecting an over-temperature condition in a fresh food or freezer compartment resulting from an interruption of power to the appliance. 
     2. Discussion of the Prior Art 
     In general, refrigerated appliances include a freezer compartment for maintaining foodstuffs at or below freezing, and a fresh food compartment for maintaining foodstuffs in a temperature zone below ambient temperature but above freezing temperatures. A typical refrigerator includes an electrically powered refrigeration system having at least a compressor, a condenser, a condenser fan, an evaporator coil, evaporator fan and a plurality of temperature sensors. 
     In operation, a consumer selects a desired temperature for each of the fresh food and freezer compartments or, in the alternative, a preset temperature value is provided by the manufacturer. Once power is introduced to the appliance, the refrigeration system operates to establish and maintain the selected temperature within each of the fresh food and freezer compartments. During periods of normal use, each of the compartments is accessed several times during a typical day. Each time a compartment door is opened, the temperature inside the compartment rises due to an influx of warmer, ambient air. Sensors arranged within the compartments function to detect any rise in temperature, and in response, the refrigeration system is actuated to return the affected compartment to the selected temperature. Certainly, if the compartment is sealed, the refrigeration system will operate for a short time period in order to re-establish the selected temperature level. However, if the compartment remains open, i.e. the consumer fails to properly close a compartment door, the refrigeration system will operate continuously in order to try to maintain the proper temperature level. 
     Obviously, with the door open, no matter how efficient the refrigeration system, the temperature of the compartment will not reach the desired level. The warmer, ambient temperature will enter and raise the temperature of the unsealed compartment. Left unchecked, the temperature could rise to a level that would detrimentally affect food stored within the appliance. In addition to problems associated with open appliance doors, compartment temperatures will rise during periods of power interruption. 
     When power is interrupted to the appliance, the refrigeration system is unable to function. Despite the existence of seals about the appliance which prevent the influx of air to the compartment, over time, ambient air will leak into the appliance. The temperature of the compartment will rise, and if power is interrupted for a prolonged period, food within the appliance will spoil. When power is returned, the refrigeration system will operate normally, pulling down the compartment temperature to the selected level. Left unaware, the consumer may inadvertently consume spoiled food items. 
     Therefore, based on the above, there exists a need in the art of refrigerators for a power interrupt system that provides an indication to a consumer of an over-temperature condition developed during periods of power interruption. Specifically, to a power interrupt system which will display to the consumer the highest temperature reached during the period of the power interruption so that an informed decision can be made as to the likelihood that the food stored within the appliance has spoiled. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an power interrupt system for a refrigerated appliance. More particularly, the power interrupt system is provided to detect an out-of-range temperature condition for fresh food and freezer compartments of the refrigerated appliance after the occurrence of a power interruption. In accordance with one form of the present invention, the power interrupt system includes a control unit having a temperature selector element, a central processor including a memory storage module, and a plurality of temperature sensors arranged about the appliance. The temperature sensors, in combination with the control unit, function to monitor fresh food and freezer compartment temperatures and activate a refrigeration system upon a sensed cooling demand. In operation, the power interrupt system compares sensed temperature values with stored temperature variables. If, after a power interruption, the sensed temperatures exceed the stored temperature variables by a predetermined amount, a power interrupt or over-temperature flag is triggered. 
     In accordance with another preferred form of the invention, a first variable set, defined by an interrupt temperature for each of the fresh food and freezer compartments, is stored in the memory module. Preferably, the interrupt temperature represents the lowest possible temperature setting for the respective refrigerator compartment. A second variable set, defined by a current set point temperature for each compartment, is also stored in the memory module. Upon activation, after sensing a power interruption and subsequent re-initialization of power to the appliance, the control unit begins monitoring the post power interrupt temperatures for the compartments. Each time the control unit scans post power interrupt temperatures for the compartments, the values obtained are compared to the values stored in the first and second variable sets. If the current post power interrupt temperature exceed the corresponding value stored in the first or second variable sets, an out of temperature range flag is triggered and a visual indication to this effect is displayed to the consumer. 
     In the most preferred form of the invention, the refrigerated appliance includes an exteriorly mounted control panel having an alpha-numeric display. Once the out-of-range temperature flag is triggered, an alarm indicating the over temperature condition is activated. In the most preferred form, the display flashes the out-of-range temperature value for a particular compartment intermittently with the current compartment temperature value. More specifically, the display is continuously updated such that the highest temperature value realized by the compartment is displayed to the consumer. In addition to the out-of-range temperatures, the display will provide the consumer with an indication that a power interruption has occurred. This can take the form of a flashing display, an audible signal, or a combination thereof. In this manner, the consumer can decide if the compartment temperature was elevated to a point that would necessarily result in spoilage to the food stored within the compartment. Preferably, the display will continue to flash the alarm until a reset button is manipulated, thus ensuring that the consumer was made aware of the alarm condition. 
     Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a refrigerated appliance employing the power interrupt system of the present invention; 
     FIG. 2 is a partially exploded view showing various components of the power interrupt system of the present invention; 
     FIG. 3 is a block diagram depicting the interrelationship between components of the power interrupt system of FIG. 2; and 
     FIG. 4 is a flow diagram setting forth a preferred control algorithm for the method of operating the power interrupt system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to FIG. 1, a refrigerator having a power interrupt system constructed in accordance with the present invention is generally indicated at  2 . Refrigerator  2  is shown to include a freezer door  6  having an associated handle  7  and a fresh food door  10  having an associated handle  11 . In the embodiment shown, refrigerator  2  is of the recessed type such that, essentially, only freezer and fresh food doors  6  and  10  project forward of a wall  15 . The remainder of refrigerator  2  is recessed within wall  15  in a manner similar to a plurality of surrounding cabinets generally indicated at  18 - 23 . Refrigerator  2  also includes a plurality of peripheral trim pieces  28 - 30  to blend refrigerator  2  with cabinets  18 - 23 . One preferred embodiment employs trim pieces  28 - 30  as set forth in commonly assigned U.S. Patent Application entitled “Fastening System for Appliance Cabinet Assembly” filed on even date herewith and which is incorporated herein by reference. 
     In another preferred embodiment, refrigerator  2  is preferably designed with main components of a refrigeration system positioned behind an access panel  32  arranged directly above trim piece  29 . In one preferred form of the invention, as will be detailed more fully below, a control and display unit  34  is mounted to an upper portion of freezer door  6 . More specifically, control and display unit  34  constitutes an electronic control panel  35  having arranged thereon a plurality of control elements  36  to enter desired operating temperatures and a digital display  37  to show temperature set points and/or actual compartment temperatures. Preferably, control and display unit  34  includes consumer operated switches to change the displays from ° F to ° C and vise versa, various alarm indications, such as power interruption and door ajar indicators, service condition signals and, in models incorporating water filters, a filter change reminder. 
     As shown in FIG. 2, refrigerator  2  includes a cabinet shell  38  defining a freezer compartment  40  and a fresh food compartment  43 . For details of the overall construction of cabinet shell  38 , reference is again made to the above-identified U.S. Patent Application entitled “Fastening System for Appliance Cabinet Assembly.” Shown arranged on a rear wall  44  of fresh food compartment  43  are a plurality of elongated metal shelf rails  46 . Each shelf rail  46  is provided with a plurality of shelf support points, preferably in the form of slots  47 , adapted to accommodate a plurality of vertically adjustable, cantilevered shelves (not shown). Since the manner in which such shelves can be constructed and supported may vary and is not considered part of the present invention, the shelves have not been depicted for the sake of clarity of the drawings and will not be discussed further here. However, for purposes which will be set forth further below, it should be noted that each of rails  46  preferably extends from an upper portion, through a central portion, and down into a lower portion (each not separately labeled) of fresh food compartment  43 . 
     In the embodiment shown, mounted behind access panel  32  are various components of the refrigeration system employed for refrigerator  2 . More specifically, the refrigeration system includes at least a variable speed compressor  49 , an evaporator  52  and a condenser  61 . Preferably, each of the components is operated in an optimum manner based upon sensed cooling demand within refrigerator  2 . 
     In addition to the aforementioned components, mounted to an upper portion of fresh food compartment  43  is an air manifold  90  for use in directing a cooling airflow through fresh food compartment  43  of refrigerator  2 . More specifically, interconnected to air manifold  90  are a first recirculation duct  94  having an inlet  95  exposed in a lower portion of fresh food compartment  43 , a second recirculation duct  96  having an inlet  97  exposed at an upper portion of fresh food compartment  43 , and an intake duct  100  establishing an air path for a flow of fresh cooling air from freezer compartment  40  into manifold  90 . Arranged in fluid communication with air manifold  90  is a fresh food stirring fan  110 . Stirring fan  1   10  is adapted to receive a combined flow of air from recirculation ducts  94  and  96 , as well as intake duct  100 , and to disperse the combined flow of air into the fresh food compartment  43 . With this arrangement, stirring fan  110  draws in a flow of air, which is generally indicated by arrows A, through inlets  95  and  97  of ducts  94  and  96 , and intake duct  100 , while subsequently exhausting the combined flow of cooling air, represented by arrow B, through an outlet  125 . Most preferably, outlet  125  directs the air flow in various directions in order to generate a desired flow pattern based on the particular configuration of fresh food compartment  43  and any additional structure provided therein. The exact positioning of inlets  95  and  97  also depend on the particular structure provided. In one preferred arrangement, inlet  95  of duct  94  is located at a point behind at least one food storage bin (not shown) arranged in a bottom portion of fresh food compartment  43 . The air flow past the storage bin is provided to aid in maintaining freshness levels of food contained therein. For this purpose, an additional passage leading from freezer compartment  40  into fresh food compartment  43  can be provided as generally indicated at  128 . While not part of the present invention, the details of the storage bin are described in commonly assigned U.S. Pat. No. 6,170,276 which is hereby incorporated by reference. 
     In order to regulate the amount of cooling air drawn in from freezer compartment  40 , a multi-position damper  130  is provided either at an entrance to or within intake duct  100 . When the cooling demand within fresh food compartment  43  rises, damper  130  opens to allow cooling air to flow from freezer compartment  40  to fresh food compartment  43  and, more specifically, into intake duct  100  to manifold  90  and stirring fan  110 . A flow of air to be further cooled at evaporator  52  is lead into an intake  135  of a return duct  137 . In the embodiment shown, return duct  137  is preferably located in the upper portion of fresh food compartment  43 . For details of the overall operation and arrangement of the temperature control system of refrigerator  2 , reference is made to commonly assigned U.S. Patent Application entitled “Temperature Control System for a Refrigerated Compartment” filed on even date herewith and which is hereby incorporated by reference. 
     It should be understood that the above description is provided for the sake of completeness and that the present invention is particularly directed to a power interrupt system for refrigerator  2 . More particularly, the power interrupt system detects an over-temperature condition and provides an indication of the highest temperature reached within either freezer compartment  40  or fresh food compartment  43  after a period of power interruption to refrigerator  2 . 
     Reference will now be made to FIG. 3 depicting a preferred embodiment of the present invention. As shown, a power interrupt system  160  includes a central processor or CPU  170  having a memory storage module  173 . CPU  170  is adapted to receive input signals from control and display unit  34 , in addition to a plurality of temperature sensors, two of which are constituted by a freezer temperature sensor  180  and a fresh food temperature sensor  185  (also shown in FIG.  2 ). Power interrupt system  160  is selectively activated through one of the plurality of control elements  36  on control and display unit  34 . Upon activation, power interrupt system  160  monitors the temperature of freezer compartment  40  and fresh food compartment  43  after detecting a power interruption. Once power is restored to refrigerator  2  following a power failure, as will be detailed more fully below, power interrupt system  160  determines if the temperature of either freezer compartment  40  or fresh food compartment  43  exceeds a predetermined value. If so, power interrupt system  160  outputs to digital display  37  an indication of the highest temperature reached in each compartment until a reset button  189  is activated. 
     Having described various of the components of power interrupt system  160 , a preferred method of operation will be set forth with particular reference to FIG. 4 depicting a preferred control algorithm. Upon application of electrical power to refrigerator  2 , control and display unit  34  and power interrupt system  160  are initialized in step  195 . During the initial start-up sequence, a first variable set, defined by a value representing the respective set point temperatures for each of the freezer and fresh food compartments  40  and  43 , is established. Simultaneously, a second variable set, defined by a value representing an interrupt temperature, is also established. In accordance with this preferred embodiment, the interrupt temperature values constitute the lowest possible temperature setting for each compartment. In any event, the respective variable sets are stored in memory storage module  173 . 
     After an the initial power-up, be it through an initial application of power to the system or after a power interruption, temperature sensors  180  and  185  are polled in step  197  to determine current temperature values for both the freezer and fresh food compartments  40  and  43 . After determining the current temperature values for the respective compartments, in step  199 , a determination is made whether power interrupt system  160  is enabled. If, in step  199 , power interrupt system  160  is determined to be enabled, then, in step  201 , the current temperature value for each compartment is compared to the values stored in the first variable set. 
     If, after performing step  201 , either the freezer or fresh food compartment temperatures are found to exceed the corresponding values stored in the first variable set by more than a first predetermined amount, preferably at least 3° F., a power interrupt or over-temperature trip flag is established in step  205 . Once the over-temperature flag is enabled, the value stored in the second variable set, corresponding to the temperature values found to satisfy the requirement of step  201 , is replaced with the new values in step  206 . After the completion of step  206 , the process moves to step  207  in which digital display  37  is caused to alternately flash a power interrupt signal, the current temperature of both the freezer and fresh food compartments  40  and  43  and the new value or values stored in the second variable set. In addition, an audible warning may accompany the visible warning provided by digital display  37 . With this arrangement, the consumer is provided with an indication that a power interrupt has occurred and, additionally, the highest temperature reached by either compartment during the power interrupt, as well as current compartment temperatures. 
     Conversely, if in step  201  neither of the current temperature values sensed in step  197  exceeds the values stored in the first variable set by the predetermined value, the control algorithm moves to step  210  in which the current temperatures are compared to the values stored in the second variable set. In a manner similar to that described above, if the current temperature values exceed the values stored in the second variable set by a second predetermined amount, preferably at least 2° F., power interrupt system  160  performs steps  205 - 207 . 
     In either case, digital display will continue to perform step  207  until, in step  211 , it is determined that reset button  189 , is actuated. After reset control  189  is actuated, signaling that the consumer is made aware of the power interrupt and any resulting rise in temperature, the control algorithm moves to steps  213 - 215  before terminating at step  220 . In step  213  digital display  37  ceases to flash the warning established in step  207 . Next, the power interrupt trip flag is disabled in step  214  and, finally, in step  215 , the values stored in the second variable set are reset to the minimum set point temperatures establish at the onset of the process. 
     Although described with reference to a preferred embodiment of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, the particular location of the control and display unit is not important so long as it provides the consumer with a readily visible indication of the status of the appliance. Additionally, the particular temperature values that trigger the power interrupt system can be varied without departing from the scope of the present invention. Finally, while the refrigeration system is described as being operable with variable speeds, it should be understood that the power interrupt system of the present invention is applied to standard refrigeration systems as well. In general, the invention is only intended to be limited by the scope of the following claims.