Abstract:
A method for controlling a damper having a closed position and an open position for providing flow communication between a first cooled compartment and a second cooled compartment is provided. The method includes toggling the damper from an initial position of the damper to a position different from the initial position and then back to the initial position on a periodic basis.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to sealed system refrigeration devices, and more particularly, to controlling a damper in refrigerators. 
     Modern refrigerators typically include a compressor, an evaporator, and a condenser in a closed refrigeration circuit, and a number of fans that facilitate the refrigeration circuit and direct cooled air into refrigeration compartments. Conventionally, the condenser, evaporator and condenser are operated at a single speed, and a plurality of single speed fans are employed in association with the condenser, evaporator, condenser and also to direct cooled air throughout the refrigerator. Collectively, these components are sometimes referred to as a sealed system. While these single speed sealed systems have been satisfactory in the past, they are now perceived as disadvantageous in several aspects. 
     For example, such single speed systems often entail considerable temperature variation in operation of the refrigerator as the sealed system cycles on an off. Further, the refrigerator can sometimes be undesirably noisy as it cycles from an off or relatively silent condition to an on condition with the sealed system components energized. In addition, single speed systems are not as energy efficient as desired. 
     While most of these disadvantages can be addressed by using multiple speed or variable speed fans and sealed system components, use of variable speed components has caused changes in the way refrigerators are operated. For example, in variable systems the duty cycle of the compressor is nearly continuous while in single speed systems the duty cycle is much less than nearly continuous. For example, in one known single speed system the duty cycle is 50%. However, a nearly continuous duty cycle may cause undesirable ice build up. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, a method for controlling a damper having a closed position and an open position for providing flow communication between a first cooled compartment and a second cooled compartment is provided. The method includes toggling the damper from an initial position of the damper to a position different from the initial position and then back to the initial position on a periodic basis. 
     In another aspect, a cooling device includes a first compartment including a plurality of first walls and at least one first door defining a first enclosed volume of the first compartment and a second compartment including a plurality of second walls and at least one first door defining a first enclosed volume of the second compartment with one of the first walls. A damper is between the first compartment and the second compartment, the damper is movable to change an amount of flow communication between the first compartment and the second compartment. A sealed system is configured to provide cooling capacity to the first compartment and the second compartment is operationally coupled to the first compartment and to the second compartment. A temperature control system is operationally coupled to the damper and to the sealed system. The control system is configured to toggle the damper from an initial position to a position different from the initial position and then back to the initial position on a periodic basis. 
     In a further aspect, a refrigerator includes a first compartment configured to preserve food, the first compartment including a plurality of first walls and at least one first door defining a first enclosed volume of the first compartment, and a second compartment configured to preserve food coupled to one of the first walls, the second compartment including a plurality of second walls and at least one second door defining a second enclosed volume of the second compartment with one of said first walls comprising a damper movable to change an amount of flow communication between the first compartment and the second compartment. A sealed system is operationally coupled to the first and second compartments, the sealed system is configured to provide cooling capacity to the first and second compartments. A temperature control system is operationally coupled to the sealed system and to the damper. The control system is configured to maintain the first compartment at a first temperature, maintain the second compartment at a second temperature different from the first temperature, and toggle the damper from an initial position to a position different from the initial position and then back to the initial position on a periodic basis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an exemplary refrigerator. 
     FIG. 2 is a block diagram of a refrigerator controller in accordance with one embodiment of the present invention. 
     FIG. 3A is a portion of a block diagram of the main control board shown in FIG.  2 . 
     FIG. 3B is a portion of a block diagram of the main control board shown in FIG.  2 . 
     FIG. 3C portion of a block diagram of the main control board shown in FIG.  2 . 
     FIG. 4 is a block diagram of the main control board shown in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a side-by-side refrigerator  100  in which the present invention may be practiced. It is recognized, however, that the benefits of the present invention apply to other types of refrigerators, freezers, refrigeration appliances, and refrigeration devices, including climate control systems having similar control issues and considerations. Consequently, the description set forth herein is for illustrative purposes only and is not intended to limit the invention in any aspect. 
     Refrigerator  100  includes a fresh food storage compartment  102  and a freezer storage compartment  104 . Freezer compartment  104  and fresh food compartment  102  are arranged side-by-side in an outer case  106  with inner liners  108  and  110 . A space between case  106  and liners  108  and  110 , and between liners  108  and  110 , is filled with foamed-in-place insulation. Outer case  106  normally is formed by folding a sheet of a suitable material, such as pre-painted steel, into an inverted U-shape to form top and side walls of case. A bottom wall of case  106  normally is formed separately and attached to the case side walls and to a bottom frame that provides support for refrigerator  100 . 
     Inner liners  108  and  110  are molded from a suitable plastic material to form freezer compartment  104  and fresh food compartment  102 , respectively. Alternatively, liners  108 ,  110  may be formed by bending and welding a sheet of a suitable metal, such as steel. The illustrative embodiment includes two separate liners  108 ,  110  as it is a relatively large capacity unit and separate liners add strength and are easier to maintain within manufacturing tolerances. In smaller refrigerators, a single liner is formed and a mullion spans between opposite sides of the liner to divide it into a freezer compartment and a fresh food compartment. 
     A breaker strip  112  extends between a case front flange and outer front edges of liners. Breaker strip  112  is formed from a suitable resilient material, such as an extruded acrylo-butadiene-styrene based material (commonly referred to as ABS). 
     The insulation in the space between liners  108 ,  110  is covered by another strip of suitable resilient material, which also commonly is referred to as a mullion  114 . Mullion  114  also preferably is formed of an extruded ABS material. It will be understood that in a refrigerator with separate mullion dividing a unitary liner into a freezer and a fresh food compartment, a front face member of mullion corresponds to mullion  114 . Breaker strip  112  and mullion  114  form a front face, and extend completely around inner peripheral edges of case  106  and vertically between liners  108 ,  110 . Mullion  114 , insulation between compartments  102 ,  104 , and a spaced wall of liners  108 ,  110  separating compartments  102 ,  104  sometimes are collectively referred to herein as a center mullion wall  116 . 
     Shelves  118  and slide-out drawers  120  normally are provided in fresh food compartment  102  to support items being stored therein. A bottom drawer or pan  122  partly forms a quick chill and thaw system (not shown) and selectively controlled, together with other refrigerator features, by a microprocessor (not shown in FIG. 1) according to user preference via manipulation of a control interface  124  mounted in an upper region of fresh food storage compartment  102  and coupled to the microprocessor. A shelf  126  and wire baskets  128  are also provided in freezer compartment  104 . In addition, an ice maker  130  may be provided in freezer compartment  104 . 
     A freezer door  132  and a fresh food door  134  close access openings to fresh food and freezer compartments  102 ,  104 , respectively. Each door  132 ,  134  is mounted by a top hinge  136  and a bottom hinge (not shown) to rotate about its outer vertical edge between an open position, as shown in FIG. 1, and a closed position (not shown) closing the associated storage compartment. Freezer door  132  includes a plurality of storage shelves  138  and a sealing gasket  140 , and fresh food door  134  also includes a plurality of storage shelves  142  and a sealing gasket  144 . 
     In accordance with known refrigerators, refrigerator  100  also includes a machinery compartment (not shown) that at least partially contains components for executing a known vapor compression cycle for cooling air. The components include a compressor (not shown in FIG.  1 ), a condenser (not shown in FIG.  1 ), an expansion device (not shown in FIG.  1 ), and an evaporator (not shown in FIG. 1) connected in series and charged with a refrigerant. The evaporator is a type of heat exchanger which transfers heat from air passing over the evaporator to a refrigerant flowing through the evaporator, thereby causing the refrigerant to vaporize. The cooled air is used to refrigerate one or more refrigerator or freezer compartments via fans (not shown in FIG.  1 ). Collectively, the vapor compression cycle components in a refrigeration circuit, associated fans, and associated compartments are referred to herein as a sealed system. The construction of the sealed system is well known and therefore not described in detail herein, and the sealed system components are operable at varying speeds to force cold air through the refrigerator subject to the following control scheme. 
     FIG. 2 illustrates an exemplary controller  160  in accordance with one embodiment of the present invention. Controller  160  can be used, for example, in refrigerators, freezers and combinations thereof, such as, for example side-by-side refrigerator  100  (shown in FIG.  1 ). 
     Controller  160  includes a diagnostic port  162  and a human machine interface (HMI) board  164  coupled to a main control board  166  by an asynchronous interprocessor communications bus  168 . An analog to digital converter (“A/D converter”)  170  is coupled to main control board  166 . A/D converter  170  converts analog signals from a plurality of sensors including one or more fresh food compartment temperature sensors  172 , a quick chill/thaw feature pan (i.e., pan  122  shown in FIG. 1) temperature sensors  174 , freezer temperature sensors  176 , external temperature sensors (not shown in FIG.  2 ), and evaporator temperature sensors  178  into digital signals for processing by main control board  166 . 
     In an alternative embodiment (not shown), A/D converter  170  digitizes other input functions (not shown), such as a power supply current and voltage, brownout detection, compressor cycle adjustment, analog time and delay inputs (both use based and sensor based) where the analog input is coupled to an auxiliary device (e.g., clock or finger pressure activated switch), analog pressure sensing of the compressor sealed system for diagnostics and power/energy optimization. Further input functions include external communication via IR detectors or sound detectors, HMI display dimming based on ambient light, adjustment of the refrigerator to react to food loading and changing the air flow/pressure accordingly to ensure food load cooling or heating as desired, and altitude adjustment to ensure even food load cooling and enhance pull-down rate at various altitudes by changing fan speed and varying air flow. 
     Digital input and relay outputs correspond to, but are not limited to, a condenser fan speed  180 , an evaporator fan speed  182 , a crusher solenoid  184 , an auger motor  186 , personality inputs  188 , a water dispenser valve  190 , encoders  192  for set points, a compressor control  194 , a defrost heater  196 , a door detector  198 , a mullion damper  200 , feature pan air handler dampers  202 ,  204 , and a quick chill/thaw feature pan heater  206 . Main control board  166  also is coupled to a pulse width modulator  208  for controlling the operating speed of a condenser fan  210 , a fresh food compartment fan  212 , an evaporator fan  214 , and a quick chill system feature pan fan  216 . 
     FIGS. 3A,  3 B,  3 C (collectively referred to as FIG.  3 ), and  4  are more detailed block diagrams of main control board  166 . As shown in FIGS. 3 and 4, main control board  166  includes a processor  230 . Processor  230  performs temperature adjustments/dispenser communication, AC device control, signal conditioning, microprocessor hardware watchdog, and EEPROM read/write functions. In addition, processor  230  executes many control algorithms including sealed system control, evaporator fan control, defrost control, feature pan control, fresh food fan control, stepper motor damper control, water valve control, auger motor control, cube/crush solenoid control, timer control, and self-test operations. 
     Processor  230  is coupled to a power supply  232  which receives an AC power signal from a line conditioning unit  234 . Line conditioning unit  234  filters a line voltage which is, for example, a 90-265 Volts AC, 50/60 Hz signal. Processor  230  also is coupled to an EEPROM  236  and a clock circuit  238 . 
     A door switch input sensor  240  is coupled to fresh food and freezer door switches  242 , and senses a door switch state. A signal is supplied from door switch input sensor  240  to processor  230 , in digital form, indicative of the door switch state. Fresh food thermistors  244 , a freezer thermistor  246 , at least one evaporator thermistor  248 , a feature pan thermistor  250 , and an ambient thermistor  252  are coupled to processor  230  via a sensor signal conditioner  254 . Conditioner  254  receives a multiplex control signal from processor  230  and provides analog signals to processor  230  representative of the respective sensed temperatures. Processor  230  also is coupled to a dispenser board  256  and a temperature adjustment board  258  via a serial communications link  260 . Conditioner  254  also calibrates the above-described thermistors  244 ,  246 ,  248 ,  250 , and  252 . 
     Processor  230  provides control outputs to a DC fan motor control  262 , a DC stepper motor control  264 , a DC motor control  266 , and a relay watchdog  268 . Watchdog  268  is coupled to an AC device controller  270  that provides power to AC loads, such as to water valve  190 , cube/crush solenoid  184 , a compressor  272 , auger motor  186 , a feature pan heater  206 , and defrost heater  196 . DC fan motor control  266  is coupled to evaporator fan  214 , condenser fan  210 , fresh food fan  212 , and feature pan fan  216 . DC stepper motor control  266  is coupled to mullion damper  200 , and DC motor control  266  is coupled to one of more sealed system dampers. 
     Periodically, controller  160  reads fresh food compartment thermistors  244  and freezer thermistor  246  to determine respective temperatures of fresh food compartment  102  (shown in FIG. 1) and freezer compartment  104  (shown in FIG.  1 ). Based on the determined temperatures of compartments  102 ,  104 , controller  160  makes control algorithm decisions, including selection of operating speed of the various sealed system components, as described below. 
     Additionally, mullion damper  200  is toggled on a periodic basis to prevent frost buildup that may impair movement of mullion damper  200  or prevent proper operation thereof. That is, when the damper is in a closed position it is toggled to an opened position and returned to the closed position, and when the damper is in an opened position it is toggled to the closed position and returned to the open position. In an exemplary embodiment, damper  200  is toggled at thirty minute intervals. In alternative embodiments, however, damper  200  may be toggled more regularly or less regularly. For example, damper is toggled periodically with a periodicity of between approximately 10 minutes and approximately 60 minutes, with a periodicity between approximately 15 minutes and approximately 45 minutes, with a periodicity between approximately 25 minutes and approximately 35 minutes, with a periodicity between approximately 15 minutes and approximately 50 minutes, with a periodicity between approximately 20 minutes and approximately 40 minutes, or with a periodicity between approximately 25 minutes and approximately 35 minutes. Additionally, toggling may occur the same or different time that compartment temperatures are read or control parameters are adjusted. Also toggling is both done during a defrost mode in which the temperature of freezer compartment  104  is allowed to warm up, and during a cooling mode in which one or both of freezer compartment  104  and fresh food compartment  102  are being cooled. 
     By toggling damper  200  on a periodic basis, any ice that builds up on damper  200  and/or damper gears (not shown) is broken up and does not allow a substantial amount of ice build up such that damper  200  is frozen in one position and no longer moveable. Accordingly, a cost effective refrigerator is provided that is long lasting and has an improved damping system over known damping systems. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.