Patent Publication Number: US-8122730-B2

Title: Method and device for managing the operating conditions of a refrigerator compartment using a single sensor

Description:
BACKGROUND OF THE INVENTION 
     Current refrigerator designs include a plurality of mechanisms for the control of different functions. For example, one mechanism controls the temperature of the refrigerator unit while a second mechanism controls the temperature of the freezer unit. In addition, there are mechanisms for the control of through-the-door ice and water dispensing and freezer defrosting cycling. 
     However, each of these mechanisms has been developed at different times and operates essentially independently. This results in inefficient operation of the total refrigerator unit while having an increased cost because of the individual components of each mechanism. 
     Hence, a device or mechanism is needed for providing efficient control of refrigerator operation with a lower cost. 
     BRIEF DESCRIPTION OF THE INVENTION 
     As described herein, the embodiments of the present invention overcome one or more of the above or other disadvantages known in the art. 
     One aspect of the present invention relates to a method for managing the operating conditions of a refrigerator unit. The method includes the steps of determining a sensor temperature of a refrigerator unit, determining which of a plurality of disjoint temperatures regions the temperature lies within, and setting an operating condition of each of a plurality of components of said refrigerator unit based on the determined temperature region. 
     Another aspect of the present invention relates to a device for managing the operating conditions of a refrigerator unit. The device includes a processor in communication with a memory, the memory including code which when accessed by the processor causes the processor to determine a sensor temperature of a refrigerator unit, to determine which of a plurality of disjoint temperatures regions the temperature lies within, and to set an operating condition of each of a plurality of components of the refrigerator unit based on the determined temperature region. 
     Yet another aspect of the present invention relates to a device for managing operating conditions of a refrigerator unit. The device includes an input means for receiving at least one single-sensor temperature reading, processing means for determining a sensor temperature from at least one single-sensor temperature reading, and determining operating conditions of each of a plurality of components of the refrigerator unit based on said determined temperature, the operating conditions being presented in a plurality of disjoint temperature regions, and output means for outputting said determined operating conditions to each of said plurality of components. 
     These and other aspects and advantages of the present invention will become apparent from the following detailed description considered n conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a block diagram of an exemplary embodiment of the invention described herein. 
         FIG. 2  is a flow chart of an exemplary process of the invention described herein. 
         FIG. 3  is a flow chart of a second exemplary process of the invention described herein. 
         FIG. 4  is a system for implementing the processing shown in  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION 
       FIG. 1  illustrates an exemplary multi-functional system  100  in accordance with the principles of the invention. Processing unit  170 , which is composed of microcontroller  175  and is in communication with temperature/encoder board  110 , dispenser board  120 , evaporator fan  130 , compressor  140 , defrost heater  150 , and switches  180 ,  185  and  190 . Switches  180 ,  185  and  190  are related to the refrigerator door of the fresh food compartment (FF Door), the refrigerator door of the freezer compartment (FZ Door) and a compressor running indication, respectively. 
     Microcontroller  175  receives information from temperature/encoder board  110  and provides setting to the temperature encoder/board  110  to maintain the refrigerator unit at a desired temperature. Similarly, microcontroller  175  receives input from dispenser board  120  to dispense water or ice, dependent upon a switch setting (not shown). Microcontroller  175 , in response, then provides signals to the dispenser board  120  to allow dispensing of water or ice, as desired. For example, microcontroller  175  may provide a signal to open a water valve when water is to be dispensed. 
     Microcontroller  175  may further sense and/or control the position of one or more of switches  176 ,  177 ,  178 ,  180 ,  185  and  190  to manage the operation of the refrigerator in an efficient manner. For example, microcontroller  175  may periodically control switch  178  to allow defrost heater  150  to provide heat to defrost the refrigerator unit (not shown) and/or the freezer unit (not shown). Similarly, microcontroller  175  may periodically control switches  176  and  177  to control evaporator fan  130  and compressor  140 , respectively. The period of controlling each switch and the duration the switch is in a first position or a second position is dependent upon the operating conditions of the refrigerator unit. These values may be set at nominal or preset values and adapted based on the operating conditions of the refrigerator unit. 
     Microcontroller  175  receives a status of switches  180 ,  185  and  190  and adapts its processing based on the status of these switches. For example, when switch  180 , which is associated with refrigerator door, indicates that the refrigerator door is open, dispensing of water or ice may be inhibited. In another example, when switch  185  indicates the freezer door is open, the compressor  140  or defrost heater  150  may be inhibited from being activated. 
     Microcontroller  175  further receives a temperature input from a temperature sensor such as a thermistor  160 . Thermistor  160  monitors and provides information regarding variations in temperature in the fresh food Compartment of the refrigerator unit. In one aspect of the invention, the thermistor  160  may read a temperature in defined periodic intervals. For example, a current temperature may be obtained every 2 minutes by polling the thermistor  160  for its current temperature value. In other aspects of the invention, the period of polling may be greater or less than the exemplary 2-minute value presented herein. 
     In accordance with the principles of the invention, the integration of the numerous functions within a single microcontroller  175  provides for efficient operation of the overall system. 
       FIG. 2  illustrates a flow chart of an exemplary process for managing the operation of the system described herein. In this exemplary process, at block  210 , a reading of thermistor  160  is performed. At block  220 , a determination is made whether the measured temperature value is valid. If the answer is negative, then processing executes a default process at block  230  and processing returns to block  210 . The default process of block  230  represents a fail-safe mode to ensure quality operation of the unit with a failed thermistor. For example, in the event of an invalid thermistor reading, the decision loop will continue to re-check the thermistor  160  for one of a specified number of re-tries, or a specified time period. If a valid reading of the thermistor  160  is not obtained within these parameters, the system will use a default “fall-back” mode to maintain quality operation. The default mode may, in one aspect, set the refrigerator components to a nominal operating condition. As would be recognized, the measured value may be a current measured value or may be a processed value that includes information regarding previously measured values. As will be explained herein, the measured value may, in one aspect of the invention, be an average value of measured values taken over a period of time. 
     At block  240 , a plurality of tests regarding the measured value read from thermistor  160  are performed; 
     if the measured value (e.g., temperature) is between a first and a second value, then a first mode of operation is selected; 
     if the measured value (e.g., temperature) is between the second and third values, then a second mode of operation is selected; 
     if the measured value (e.g., temperature) is between the third and fourth value, then a third mode of operation is selected. 
     This process is repeated for each of a plurality of disjoint value (e.g., temperature) ranges to determine which of a plurality of modes of operation is to be executed. In one exemplary embodiment of the invention, the refrigerator unit will operate in accordance with the operating conditions shown in Table 1. 
     Referring to Table 1, when the measured thermistor value is greater than 55 degrees F., the elements of the refrigerator unit operate in one mode, whereas, if the thermistor indicates an operating temperature between 40 degrees and 55 degrees F., then the refrigerator components are operated in a second mode. Similarly, if the operating temperature is between 34 and 40 degrees F., then the refrigerator components are operated in a third mode and when the temperature is below 34 degrees F., the refrigerator components are operated in a fourth mode. Although, the invention is described with regard to four (4) operating temperature ranges, it would be within the knowledge of those skilled in the art to expand or reduce the number of operating ranges and the operating conditions of each of the refrigerator components within each range. In addition, two default ranges (i.e., above 150 degrees F. and below 41 degrees F.) are shown, wherein temperatures within these ranges cause the system to operate with specific default values or operating conditions. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Exemplary Operating Conditions 
               
               
                   
               
             
            
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     Referring back to  FIG. 2 , at block  250 , a determined process is executed to place the compressor  140 , condenser fan  165 , evaporator fan  130  and other elements, which are not shown, in an appropriate mode based on the measured temperature and the characteristics in the corresponding temperature range. For example, in one mode (i.e., between 40 and 55 deg. F.), each of a compressor, evaporator and condenser may operate in a medium condition while a damper may be left open. An in another example, between 34 and 40 deg. F., compressor  140 , condenser fan  165 , evaporator fan  130  are operated in a low mode and the damper is closed. In one aspect of the invention, the operating characteristics “high,” “medium,” and “low” may represent operating ranges based on a percentage of a nominal, a desired or a rated setting of the corresponding component. For example, a high condition may represent operation of a component at 100 percent of a nominal or desired or rated operating condition, a medium condition may represent operation of a component in a range of 45 to 55 percent of a nominal or desired or rated operating condition. A low condition may represent operation of a component in a range of 25-35 percent of a nominal or desired or rated operating condition. Conventional refrigerator compressor units operate within a range of 500 to 800 BTU and, hence, the high, medium, and low operating conditions for a refrigerator compressor may be determined based on the compressor rating and the aforementioned exemplary percent ranges. Similarly, typical fans operate in a range of 1000-3000 RPM and hence, the high, medium and low operating conditions may be determined based on the fan rating and the aforementioned exemplary percent ranges. In addition, the percentage ranges may be formulated so that a minimum operating condition for a component exists. By way of example, if the compressor rating is 800 BTU, a low operating condition may be set so that the output of the compressor does not fall below a known value (e.g., 400 BTU). Thus, the aforementioned low percent range referred to above (25-35 percent) may be adjusted to be 50-60 percent to insure that the compressor output does not fall below the known value. The medium percent range would also be similarly adjusted. In addition, the exemplary ranges have be described as being disjoint and non-adjacent. However, it would be within the knowledge of those skilled in the art to adjust the ranges to be disjoint and adjacent. Also from Table 1, it can be seen that default operating conditions may be set when invalid measurement is determined. 
       FIG. 3  illustrates a flowchart of an exemplary process  300  for determining a thermistor reading at block  220 . In this exemplary process, a plurality of variables and indicators are initialized at block  310 . At block  320 , a determination is made whether a count of bad temperature readings (Bad_Therm_Count) reaches a predetermined limit. If the answer is affirmative, then the sensor temperature is deemed invalid and processing is ended. 
     If the answer at block  320  is negative, then a determination is made at block  340  whether a single-sensor reading (i.e., current reading) is not within predetermined limits. If the answer is in the affirmative, then a bad term counter (Bad_Therm_Count) is increased and process continues at block  320 . For example, a refrigerator compartment may be expected to be within a range of 32-55 degrees F., and a temperature reading outside this range may be deemed to be a bad temperature reading. However, in case the operation disclosed herein is associated with a freezer compartment, then the freezer compartment may be expected to be within a temperature range of 10-30 degrees and a temperature reading outside this range, for a freezer compartment, may be deemed to be a bad temperature reading. Accordingly, the values shown in Table 1 may be adjusted based on the context of the specific operation and/or unit being monitored. 
     If the answer at block  340  is negative (i.e., the temperature reading is within predetermined limits), then the temperature reading, in this illustrated aspect of the invention, is processed such that a known number of single sensor readings are accumulated and a rolling average of the number of sensor readings is performed at block  360 . In the illustrated example, 24 readings are averaged together in a rolling average. However, it would be recognized that this number may be increased or decreased without altering the scope of the invention. As is known in the art, a rolling average is performed by taking a number of readings over a known period of time. Older values are then removed as new values are added to the period of time. At block  370 , a determination is made whether the rolling average value is within the values shown in Table 1 (which may be referred to as a temperature grid). If the answer is negative, then processing continues at block  320 . 
     However, if the answer is in the affirmative, then the compressor  140 , the condenser fan  165  and the evaporator fan  130  are set to a run condition based on the conditions defined in the grid entry corresponding to the determined rolling average value. Processing then returns to block  320  to continue monitoring the temperature value. 
     As noted above, a Bad_Therm_Count is maintained and monitored. The Bad_Therm_Count is a variable value of a number of consecutive attempts of reading the thermistor  160  before a valid temperature reading is achieved. In one exemplary embodiment of the invention, the thermistor read value may be checked for “n” consecutive times to insure it is an invalid reading, and it wasn&#39;t just a single bad reading. The number of checks “n” may be determined based on the periodic sample rate (i.e., polling rate) and a desired time before indicating a failure has occurred. The term “Single_Sensor_Therm” refers to the current reading of the thermistor. The Single_Sensor_Therm value is then accumulated, averaged and stored as “single_sensor_therm_rolling_avg.” “Single_sensor_therm_rolling_avg” may be used as the sensor temperature in step  240  ( FIG. 2 ). A rolling average, as is known in the art, provides for the accumulation and use of a fixed number of values in determining an average value and then removal of an oldest value when a new value is obtained. The use of a rolling average is advantageous in that the system doesn&#39;t change state drastically with each new thermistor reading. An example of a rapid change in temperature may occur when a refrigerator fresh food compartment door is left open allowing a rush of warm air into the refrigerator compartment. This rapid change in temperature may instantaneously change the thermistor reading, but the effect of this change is filtered by the previously accumulated values. In one aspect of the invention, a rolling average of approximately 24 previous readings is maintained to filter out instantaneous changes, and keep smooth operation of the unit. 
     Although not shown, it would be appreciated that the polling rates described herein may dynamically be adapted based on the one or more criteria. For example, while a polling rate of 2 minutes is described above to determine a obtain a measure value, the polling rate may dynamically be altered in the case of invalid individual reading or after the determination of “n” number of invalid readings. In addition, while  FIGS. 2 and 3  appear to operate sequentially (i.e., a temperature reading at block  240  invokes the processing of  FIG. 3 ), it would be appreciated that the processing shown in  FIG. 3  may operate at one level and the processing shown in  FIG. 2  may operate at a second level. For example, the polling of the thermistor  160  to obtain current temperature readings ( FIG. 3 ) may be performed at a high rate (e.g., every 0.5 seconds), and the processing of determining the operating mode ( FIG. 2 ) may be performed at a lower rate (e.g., 2 seconds). The processing of  FIG. 2  may access the rolling average value determined in  FIG. 3 . In another aspect of the invention, the processing at block  240  may be performed, serially, by the processing shown in  FIG. 3 . 
     The above-described methods according to the preferred embodiment of invention shown herein can be realized in hardware or as software or computer code that can be stored in a recording medium such as a CD ROM, an RAM, a floppy disk, a hard disk, or a magneto-optical disk or downloaded over a network, so that the methods described herein can be rendered in such software using a general purpose computer, or a special processor or in programmable or dedicated hardware, such as an ASIC or FPGA. As would be understood in the art, the computer, the processor or the programmable hardware include memory components, e.g., RAM, ROM, Flash, etc. that may store or receive software or computer code that when accessed and executed by the computer, processor or hardware implement the processing methods described herein. 
       FIG. 4  illustrates a system  400  for implementing the principles of the invention shown herein. In this exemplary system embodiment  400 , input data is received from sources  405  over network  450  and is processed in accordance with one or more programs, either software or firmware, executed by processing system  410 . The results of processing system  410  may then be transmitted over network  470  for viewing on display  480 , reporting device  490  and/or a second processing system  495 . 
     Processing system  410  includes one or more input/output devices  440  that receive data from the illustrated sources or devices  405  over network  450 . The received data is then applied to processor  420 , which is in communication with input/output device  440  and memory  430 . Input/output devices  440 , processor  420  and memory  430  may communicate over a communication medium  425 . Communication medium  425  may represent a communication network, e.g., ISA, PCI, PCMCIA bus, one or more internal connections of a circuit, circuit card or other device, as well as portions and combinations of these and other communication media. 
     Processing system  410  and/or processor  420  may be representative of a handheld calculator, special purpose or general purpose processing system, desktop computer, laptop computer, palm computer, or personal digital assistant (PDA) device, etc., as well as portions or combinations of these and other devices that can perform the operations illustrated. 
     Processor  420  may be a central processing unit (CPU) or dedicated hardware/software, such as a PAL, ASIC, FGPA, operable to execute computer instruction code or a combination of code and logical operations. In one embodiment, processor  420  may include code which, when executed by the processor, performs the operations illustrated herein. The code may be contained in memory  430 , may be read or downloaded from a memory medium such as a CD-ROM or floppy disk, represented as  483 , may be provided by a manual input device  485 , such as a keyboard or a keypad entry, or may be read from a magnetic or optical medium (not shown) or via a second I/O device  487  when needed. Information items provided by devices  483 ,  485 ,  487  may be accessible to processor  420  through input/output device  440 , as shown. Further, the data received by input/output device  440  may be immediately accessible by processor  420  or may be stored in memory  430 . Processor  420  may further provide the results of the processing to display  480 , recording device  490  or a second processing unit  495 . 
     As one skilled in the art would recognize, the terms processor, processing system, computer or computer system may represent one or more processing units in communication with one or more memory units and other devices, e.g., peripherals, connected electronically to and communicating with the at least one processing unit. Furthermore, the devices illustrated may be electronically connected to the one or more processing units via internal busses, e.g., serial, parallel, ISA bus, Micro Channel bus, PCI bus, PCMCIA bus, USB, etc., or one or more internal connections of a circuit, circuit card or other device, as well as portions and combinations of these and other communication media, or an external network, e.g., the Internet and Intranet. In other embodiments, hardware circuitry may be used in place of, or in combination with, software instructions to implement the invention. For example, the elements illustrated herein may also be implemented as discrete hardware elements or may be integrated into a single unit. 
     As would be understood, the operations illustrated may be performed sequentially or in parallel using different processors to determine specific values. Processing system  410  may also be in two-way communication with each of the sources  405 . Processing system  410  may further receive or transmit data over one or more network connections from a server or servers over, e.g., a global computer communications network such as the Internet, Intranet, a wide area network (WAN), a metropolitan area network (MAN), a local area network (LAN), a terrestrial broadcast system, a cable network, a satellite network, a wireless network, or a telephone network (POTS), as well as portions or combinations of these and other types of networks. As will be appreciated, networks  450  and  470  may also be internal networks or one or more internal connections of a circuit, circuit card or other device, as well as portions and combinations of these and other communication media or an external network, e.g., the Internet and Intranet. 
     While there has been shown, described and pointed out fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.