Patent Abstract:
A refrigerator is provided with a refrigerated compartment comprising one or more zones in thermal communication with each other and with each zone independently controlled and operated at a particular temperature. Each zone temperature is controlled by a separate evaporator or heat exchanger. A method for maintaining different temperatures in one or more zones in thermal communication with one another in a refrigerator is also provided.

Full Description:
TECHNICAL FIELD  
       [0001]     This invention relates generally to refrigerators, including refrigerators with separate temperature zones controlled by separate heat exchangers.  
       BACKGROUND  
       [0002]     Many modern refrigerators operate by sharing air flow from a single heat exchanger between a freezer compartment and a fresh food compartment to maintain each compartment at desired temperatures. In such refrigerators, colder air typically is borrowed or forced from the freezer compartment to mix with warmer air in the fresh food compartment. This colder air can be forced into the entire fresh food compartment for expedited cooling thereof, or, can be directed to certain areas of the fresh food compartment to chill certain areas more quickly. Generally, the refrigerator and freezer compartments are separated by an insulated wall, with the two compartments not being in thermal communication with each other.  
         [0003]     Some conventional refrigerators create dual temperature zones by utilizing adjustable dampers between the two compartments and a thermostat that controls the temperature required to switch off the compressor and evaporator fan. Other refrigerators employ a separate thermostat to electronically control dampers within the freezer compartment. In these refrigerators, temperature settings typically are adjusted in one compartment relative to the other compartment.  
       SUMMARY  
       [0004]     The refrigerator, as detailed herein, provides one or more temperature zones, a system for maintaining the different zones at different temperatures, a first evaporator or heat exchanger for cooling the first zone, a second evaporator or heat exchanger for cooling a separate second zone, and a system for controlling drawer temperatures within the first zone.  
         [0005]     In accordance with one embodiment, a refrigerator is provided having a cabinet with a refrigerated compartment. The refrigerated compartment comprises one or more zones in thermal communication with each other and with each zone operated at a particular temperature. In another aspect, a method for controlling the temperatures of one or more zones in a refrigerator is provided.  
         [0006]     A refrigerator as detailed herein, comprises one or more temperature zones and a system for controlling the zones at different temperatures. For a more complete understanding of the present invention, reference should be made to the following detailed description and accompanying drawings, wherein like reference numerals designate corresponding parts throughout the figures. Although the figures illustrate a refrigerator having two separate zones, the refrigerator may comprise several zones, which can be maintained at various temperatures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a diagram of a refrigerator with dual evaporators and a dual air circulation system.  
         [0008]      FIG. 2  provides a partial view of a refrigerator with first and second zones, with the first zone being in a drawer.  
         [0009]      FIG. 3  provides a partial view of a refrigerator illustrating the air ducts in the first zone.  
         [0010]      FIG. 4  provides a partial view of a refrigerator illustrating first zone air inlets and outlets.  
         [0011]      FIG. 5  provides a partial view of a refrigerator illustrating the first zone evaporator.  
         [0012]      FIG. 6  provides a partial view of a refrigerator illustrating air flow within the first zone. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Referring to  FIG. 1 , a refrigerator  5  includes a refrigeration system for cooling a first zone  10 , and a separate, second zone  100 . The second zone  100  can be, for example, a fresh food compartment, and the first zone  10  can be, for example, a chilled compartment or drawers (e.g., useful for storing meat). The refrigeration system comprises a compressor  280 , a condenser  290 , an expansion valve  300 , a first evaporator or heat exchanger  20  situated in air flow communication with the first zone  10 , and a second evaporator or heat exchanger  110  situated in air flow communication with the second zone  100 . The refrigeration system optionally can include a thermostat (not shown). The condenser typically includes a warm air exhaust fan to remove heat from the condenser. The first evaporator  20  substantially cools the first zone  10 , while the second evaporator  110  substantially cools the second zone  100 . Typically, though not necessarily, the first zone  10  is maintained about 2 to about 10° F. cooler than the second zone  100 .  
         [0014]     The first zone  10  is cooled by the circulation of air that has been passed over the first evaporator or heat exchanger  20 . A first evaporator fan  30  draws air across the first evaporator  20 , with the cooled air passing through a first duct  40 . The first evaporator fan  30  generates a first air flow  80  within the first zone  10 . Although the first duct  40  and first evaporator  20  are located behind the first zone rear wall  50  in  FIG. 1 , any number of duct configurations are possible for cooling the first zone  10 . For example, the first air flow  80  can pass through one or more ducts with one or more inlets and outlets located in various positions throughout the first zone  10 . As illustrated in  FIG. 1 , the first duct  40  is in communication with the first zone  10  by a first zone inlet  60  and a first zone outlet  70 . The first zone inlet  60  can be positioned below the first zone outlet  70 , above the first zone outlet  70 , or horizontal to the first zone outlet  70 .  
         [0015]     As provided in  FIG. 1 , the second zone  100  is cooled in manner analogous to first zone  10  by circulation of refrigerated air, which has been passed over the second evaporator or heat exchanger  110 . A second evaporator fan  120  draws air across the second evaporator  110 , typically with the cooled air passing through a second duct  130  behind the rear wall  170  of the fresh food compartment or second zone  100 . The second evaporator fan  120  generates a second air flow  200  within the second zone  100 . As illustrated in  FIG. 1 , second duct  130  is in communication with the second zone  100  by one or more second zone inlets  180  and one or more second zone outlets  190 , which can be located in any position with respect to each other. For example, the second zone inlet  180  can be positioned below the second zone outlet  190  or positioned horizontally relative to the second zone outlet  190 . Typically, the second zone inlet  180 , which admits cooled air into the second zone  100  after contact with the second evaporator  110 , is located above the second zone air outlets  190  to assist in the circulation of more dense, colder air.  
         [0016]     Although the first zone  10  is situated generally below the second zone  100 , near the bottom of the refrigerator in  FIGS. 1-5 , other arrangements are encompassed by this invention. For example, the first zone  10  can be located above the second zone  100 , between the top and bottom of the second zone  100 , beside the second zone  100 , or otherwise situated anywhere within the second zone  100 . Typically, though not necessarily, the first zone  10  is smaller than the second zone  100  and operates at a lower temperature than the second zone  100 .  
         [0017]     The elements of the refrigeration system are connected in series in a closed loop in a refrigerant flow relationship. In one aspect, the refrigerant flows in a continuous cycle through the expansion valve  300 , through the first evaporator  20 , through the second evaporator  110 , through the compressor  280 , through the condenser  290 , and returns to the expansion valve  300 . In this configuration, air in the first zone  10  passes over the first evaporator  20  and reduces the refrigerant cooling capacity before the refrigerant passes through the second evaporator  110 . Accordingly, the first zone  10  is maintained at a lower temperature than the second zone  100 , as the refrigerant continuously flows through the refrigeration system.  
         [0018]     Although one type of evaporator is shown in the Figures provided herewith, this invention is not limited to a particular type of evaporator or heat exchanger. Rather, the present invention encompasses any type of evaporator or heat exchanger known in the art. For example, an evaporator with tubes or coils in any configuration, and an evaporator with fins, plates, or similar devices attached thereto for improved heat exchange performance, and similar devices, are all encompassed by this invention. In addition, this invention also encompasses any type of compressor, condenser, and expansion device known in the art.  
         [0019]     The volume of the first evaporator  20  can be smaller than the volume of the second evaporator  110 . The internal volume of the first evaporator  20  can be decreased in several ways, for example, by decreasing the internal diameter of the evaporator coils, shortening the evaporator coils, decreasing the number of evaporator coils, or any combination thereof. Similarly, the internal volume of the second evaporator  110  can be increased in several ways, for example, by increasing the internal diameter of the evaporator coils, lengthening the evaporator coils, increasing the number of evaporator coils, or any combination thereof. For example, the first evaporator  20  can comprise coils with a smaller internal diameter than the internal diameter of the coils of the second evaporator  110 . Further, the coils of the first evaporator  20  can have an internal diameter that is about 10% to about 100% of the internal diameter of the coils of the second evaporator  110 . For example, the second evaporator  110  can comprise coils with an internal diameter of about ⅜ inch, while the first evaporator  20  can comprise coils with an internal diameter of about 3/16 inch. Here, the refrigerant would expand as it proceeded from the first evaporator  20  to the second evaporator  110 . Alternatively, the first and second evaporators can be separated by a second expansion valve through which the refrigerant further expands as it enters the first evaporator  20 .  
         [0020]     In  FIG. 1 , the first zone  10  is located below the second zone  100  and a thermally conductive wall  90  separates the two zones. The wall  90  can be formed from any material that allows the first zone  10  to be in thermal communication with the second zone  100 . The wall  90  maintains the first air flow  80  substantially independent from the second air flow  200 . In one aspect, the wall  90  is formed from metal, plastic, or glass. Typically, the wall  90  is not insulated, but could be insulated to reduce the thermal communication between the first and second zones. In other arrangements, the second zone  100  could share more than one thermally conductive common wall  90  with the first zone  10 .  
         [0021]     If desired, small gaps can be included between the rear or side walls of the refrigerator  5  and the thermally conductive wall  90  to allow air from the first and second zones to mix to a limited extent. Further, when the first zone  10  comprises one or more compartments or drawers, the first air flow  80  and the second air flow  200  generally mix during the time that the user opens the compartments or drawers. Generally, the first air flow  80  remains substantially independent from the second air flow  200 . Alternatively, the thermally conductive wall  90  can be sealed to maintain the first air flow  80  independent from the second air flow  200  when the compartments or drawers in the first zone  10  are closed.  
         [0022]     Referring now to  FIG. 2 , a front sectional view of a refrigerator  5  is shown with both the first and second evaporators or heat exchangers concealed. The evaporators or heat exchangers can be located in any position in the respective zone, as long as the first evaporator is in air flow communication with the first zone  10  and the second evaporator in air flow communication with the second zone  100 . The first evaporator can be located, for example, behind the second zone rear wall  170 , or optionally, behind the first zone rear wall (not shown). The first evaporator is in air flow communication with the first zone  10  by one or more first zone outlets (not shown) and one or more first zone inlets (not shown). The first zone inlets and outlets can be located in any position relative to each other for effective cooling of the first zone  10 . The second evaporator can also be located behind the second zone rear wall  170 . The second evaporator is in air flow communication with the second zone  100  by one or more second zone outlets  190  and one or more second zone inlets (not shown). The second zone inlets and outlets can be located in any position relative to each other for effective cooling of the second zone  100 . In  FIG. 2 , the first zone  10  is located below the second zone  100  and the two zones are separated by a thermally conductive wall  90 .  
         [0023]     As shown in  FIG. 2 , the first zone  10  can comprise a drawer  210  that abuts or is otherwise proximate the thermally conductive wall  90 . Although only one drawer is shown in  FIG. 2 , the first zone  10  can comprise multiple drawers or compartments. The first zone  10  further comprises one or more ducts for channeling air flow within the first zone  10 . For example, the first zone  10  can comprise a left duct  140 , a center duct  150 , and a right duct  160 , any combination of which can be used to circulate air through the first zone  10 . The air handling functions are separated into one or more ducts, which can function as air receiving ducts and air distributing ducts. Any of the ducts can encompass or otherwise house or conceal the first evaporator (not shown). The one or more ducts can comprise one or more inlets and outlets (not shown) for air flow communication with the first zone  10 . Further, the one or more ducts can include ribs (not shown) for channeling the air in a particular desired direction, depending on the duct and evaporator arrangement.  
         [0024]     The drawer  210  optionally has one or more openings (not shown) that correspond to inlets or outlets (not shown) in the receiving ducts or distributing ducts, for allowing air to circulate through the drawer  210 . The first zone  10  further can comprise a dial  220  or other operating means to enable a user to open or close the openings in the drawer  210 . The dial  220  can also be used in conjunction with blocking features to reduce the size of the openings in the drawer  210 . When the openings are closed, air circulates around the drawer  210 , but generally not over the thermally conductive wall  90 . When the dial is operated to open the openings in the drawer  210 , the second zone air circulates through the drawer, directly using the air flow to cool the contents of the drawer. Thus, the user can choose between two modes of operation for cooling the first zone  10 . In either mode of operation, the second air flow is maintained substantially independent from the first air flow by the thermally conductive wall  90 .  
         [0025]      FIG. 3  is a front sectional view of the refrigerator  5  illustrated in  FIG. 2  with the thermally conductive wall  90  and drawer  210  removed. Removal of the drawer  210  and wall  90  reveals the left duct  140 , right duct  160 , first zone rear wall  50 , and drawer supports  240 . As shown in  FIG. 3 , the left duct  140 , center duct  150 , and right duct  160  are not concealed behind the refrigerator walls. However, the ducts optionally can be located behind any refrigerator wall, such as the first zone rear wall  50  or the second zone rear wall  170 , in front of the refrigerator walls, or any combination thereof. Additionally, any number of ducts can be included in the first zone  10  and can be arranged in any fashion.  
         [0026]     In one aspect, the thermally conductive wall  90  rests on ledge  230 , the left duct  140 , and the right duct  160 . However, the wall  90  can be positioned in the refrigerator in any conventional manner. As illustrated in  FIG. 3 , the ledge  230  is part of the center duct  150  with the thermally conductive wall  90  abutting the center duct  150  instead of the second zone rear wall  170 . The center duct  150  and ledge  230  allow air flow from the first zone  10  into the center duct  150  through the one or more duct apertures  250  in the center duct  150  and ledge  230 . In  FIG. 3 , portions of the center duct  150  are removed to reveal the first evaporator fan  30 . The first evaporator fan  30  draws air from the first zone  10  through duct aperture  250  and over the first evaporator  20  (see  FIG. 4 ). Although the first evaporator fan is shown in the center duct in  FIG. 3 , the first evaporator fan can be located in any of the ducts for generation of air flow in the first zone.  
         [0027]     Referring now to  FIG. 4 , the refrigerator  5  from  FIG. 3  is illustrated with the left duct  140 , center duct  150 , right duct  160 , drawer supports  240 , and ledge  230  removed. Removal of the center duct  150  exposes the first zone outlet  70  and the first evaporator outlet  260 . Portions of the first evaporator  20  are visible through the first zone outlet  70  and the first evaporator outlet  260 . The first evaporator  20  is encompassed by a first evaporator duct  270 , all of which are located behind the second zone rear wall  170 . The first evaporator  20  can be located in any position in the refrigerator with corresponding ducts as long as air flow communication with the first evaporator  20  is maintained.  
         [0028]     The first evaporator fan draws air through duct aperture  250  and into the first evaporator duct  270  through the first zone outlet  70 . The air reenters the center duct  150  via the first evaporator outlet  260 , then enters the first zone  10  through any number of distributing ducts in air flow communication with the center duct  150  and the first zone  10 .  
         [0029]     In  FIG. 5 , portions of the second zone rear wall  170  are removed to reveal the first evaporator  20  as encompassed by the first evaporator duct  270 . The first evaporator duct  270  optionally can include means for channeling the air in a desired direction over the first evaporator  20 . For example, a blocking means (not shown) can be installed and can extend upwardly from the bottom of the first evaporator duct  270  to create a substantially U-shaped air flow channel in the first evaporator duct  270 . Thus, air enters the first evaporator duct  270  via the first zone outlet  70 , flows through the U-shaped channel over the first evaporator or heat exchanger  20 , and exits the first evaporator duct  270  via the first evaporator outlet  260 .  
         [0030]     In the configuration of  FIG. 6 , first air flow  80  passes through the center duct  150  and right duct  160 . The right duct  160  is in air flow communication with the first zone  10  via the first zone inlet  60 . In one aspect, the first zone inlet  60  is located near the front of the right duct  160  away from the first zone rear wall  50 . Such a configuration directs air from the front right corner of the first zone  10  to the rear left corner of the first zone  10 .  
         [0031]     The first zone typically operates at a temperature from about 4° F. to about 7° F. below the average second zone temperature. To achieve this temperature difference, the second evaporator or heat exchanger typically operates at a temperature from about 15° F. to about 20° F., which can create a second zone temperature from about 38° F. to about 43° F. The first evaporator or heat exchanger typically operates at a temperature from about −5° F. to about −10° F., which can create a first zone temperature from about 31° F. to about 34° F.  
         [0032]     Both the first and the second evaporator coils are cooled by liquid refrigerant ejected from the high pressure side of a compressor, into the corresponding low pressure evaporator coils. The condenser and condenser fans can be located in a variety of places, for example, under the compartment or on the back of the compartment, for removal of the transferred heat by exhaust or condenser fans.  
         [0033]     With respect to the above description, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art. All equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. Further, the various components of the embodiments of the present invention can be interchanged to produce further embodiments and these further embodiments are intended to be encompassed by the present invention. Various modifications can be made to the invention without departing from the scope thereof. Therefore, the foregoing is considered as illustrative only.

Technology Classification (CPC): 5