Abstract:
To allow for easier opening of a refrigerator door, a pressure relief system is provided to relieve a pressure differential or vacuum that develops due to operation and use of the refrigerator. The pressure relief system includes a check valve having an orifice with a flexible membrane. An insulation portion of the pressure relief valve, which is foamed into the cabinet, spans from the fresh food compartment to a top of the cabinet and directs air towards the rear cabinet liner for moisture condensing measures. The pressure relief assembly also includes an adapter which mounts to the cabinet top and provides a mounting surface for an air return assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of refrigerators and, more particularly, to a system for equalizing pressures between inside and outside of a refrigerator. 
     2. Discussion of the Prior Art 
     In general, a refrigerator includes a first or freezer compartment for maintaining foodstuffs at or below freezing, and a second or fresh food compartment, in fluid communication with the freezer compartment, for maintaining foodstuffs in a temperature zone between ambient and freezing temperatures. A typical refrigerator includes a refrigeration system having a compressor, a condenser, a condenser fan, an evaporator coil, and an evaporator fan. 
     In operation, temperature sensors are provided within the refrigerator to measure internal temperatures of the appliance. When a door associated with either compartment is opened, the temperature within the respective compartment will rise. When the internal temperature of the refrigerator deviates from a predetermined temperature, the refrigeration system is caused to operate such that the temperature will return to a point below a consumer selected set-point. In order to return the compartment temperature to this point, the refrigeration system is activated. 
     A supplement to compressor operation is the addition of a damper located between the evaporator and the fresh food compartment. Operation of the damper is controlled such that cool air is permitted to flow from the evaporator to the fresh food compartment. In some arrangements, a fan is mounted adjacent to the evaporator to aid in establishing the air flow. Accordingly, if the temperature of the fresh food compartment rises above the set-point, the damper is operated to allow the passage of cooling air from the evaporator compartment to the fresh food compartment. 
     In any case, due to operation of the refrigeration system or otherwise cooling of a refrigerator compartment, a temperature gradient develops between inside and outside of the refrigerator. As doors are opened and closed on a refrigerator in operation, especially in a warm, humid environment, a pressure differential can be created from outside the refrigerator to inside. This pressure differential results in the doors being hard to open. Certainly, it is desirable to maintain a fairly consistent opening force requirement. To this end, there exists a need in the art for a system to equalize pressures inside and outside a refrigerator in order to control the level of force needed to open a door of the refrigerator. Although pressure equalizing systems have been proposed in the art, the need still exists for a reliable, cost efficient, pressure relief system, particularly one which regulates a pressure controlling air flow in an effective manner. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to incorporating a pressure relief system in a refrigerator in order to allow for easier opening of a door of the refrigerator. The system serves to relieve an excessive pressure differential or vacuum condition that develops due to warm air entering the refrigerator and then cooling. In accordance with a preferred embodiment of the invention, the pressure relief system includes a check valve having an orifice with a flexible membrane attached thereto. An insulation portion of the pressure relief valve, which is foamed into the cabinet, spans from the fresh food compartment to the cabinet top. The pressure relief valve includes a portion in the fresh food compartment that directs air towards the rear cabinet liner for moisture condensing measures. The valve also includes an adapter which is secured to the cabinet top and provides a mounting surface for an air return assembly. The air return assembly is an injection molded housing which includes an opening, preferably including a flexible membrane. 
     In essence, in an effort to relieve the pressure differential, the pressure relief assembly defines a duct which serves as a pathway for pressure relief from one chamber of the refrigerator to the surrounding environment. By incorporating a check valve arrangement, the pressure relief function is performed automatically as needed. 
    
    
     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 perspective view of a refrigerator incorporating the pressure relief system of the invention; 
     FIG. 2 is a schematic view showing the various components of is the refrigerator and the pressure relief system in accordance with a preferred embodiment of the present invention; 
     FIG. 3 is a side view of the refrigerator with the pressure relief system of the invention; and 
     FIG. 4 is an exploded view of the main components of the pressure relief system according to a preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to FIG. 1, a refrigerator constructed in accordance with the present invention is generally shown 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 U.S. Patent Application entitled “Fastening System for Appliance Cabinet Assembly” is filed on even date herewith and which is incorporated herein by reference. Finally, as will be described more fully below, refrigerator  2  is preferably designed with main components of a refrigeration system positioned behind an access panel  32  arranged directly above trim piece  29 . 
     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 made to U.S. Patent Application entitled “Fastening System for Appliance Cabinet Assembly” filed on even date herewith and incorporated herein by reference. 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) in a manner known in the art. Since the structure of shelves can 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. 
     Preferably mounted behind access panel  32  are components of the refrigeration system employed for refrigerator  2 . More specifically, the refrigeration system includes a variable speed compressor  49  which is operatively connected to both an evaporator  52  through conduit  55 , and a condenser  61  through conduit  63 . Arranged adjacent to evaporator  52  is a variable speed evaporator fan  70  adapted to provide a variable airflow to evaporator  52 . Similarly, arranged adjacent to condenser  61  is a condenser fan  75  adapted to provide an airflow across condenser  61 . 
     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, 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 variable speed fresh food stirring fan  110 . Stirring fan  110  is adapted to receive a combined flow of air from recirculation ducts  94  and  95 , 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 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 embodiment, 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 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 variable position damper  130  is provided either at an entrance to or within intake duct  100 . As will be discussed more fully below, when the cooling demand within fresh food compartment  43  rises, variable position 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 . 
     This overall refrigeration system synergistically operates to both maintain the temperature within fresh food compartment  43  at a substantially uniform temperature preferably established by an operator and minimizes stratification of the temperature in fresh food compartment  43 . The particular manner in which the refrigeration system described above operates does not form part of the present invention. Instead, the operation of the refrigeration system is covered in U.S. Patent Applications entitled “Variable Speed Refrigeration System” and “Temperature Control System for a Refrigerated Compartment” filed on even date herewith and incorporated herein by reference. 
     The above description of the refrigerator  2  has basically been provided for the sake of completeness. The present invention is actually directed to the inclusion of a pressure relief system, generally indicated at  200  in this figure, in refrigerator  2 . In general, pressure relief system  200  functions to equalize a pressure differential developing between both freezer and fresh food compartments  40  and  43  and the surrounding environment. That is, due to operation of the refrigeration system, air within refrigerator  2  will be cooled which can create a vacuum, particularly within fresh food compartment  43 . For instance, when door  6  is opened, warm air enters refrigerator  2 . Thereafter, upon attempting to open fresh food door  10 , a created vacuum can increase the force needed to open door  10 . The present invention addresses this potential problem as will be detailed fully below with particular reference to FIGS. 3 and 4. 
     In accordance with the most preferred embodiment of the invention, pressure relief system  200  includes a pressure relief valve  210 , a mounting adapter  213  and an air return housing  216 . More specifically, as best shown in FIG. 4, pressure relief valve  210  includes a main body portion  220  provided with a central bore  222  and a peripheral flat  224 . At an upper portion  226  of main body portion  220  is arranged a truncated, conical port  228  leading into central bore  222 . Preferably, port  228  is formed with a flexible membrane  231  that defines a check valve. More specifically, flexible membrane  231  is connected about a significant portion of central bore  222  to automatically open an air passage defined by central bore  222  when a differential pressure develops across pressure relief valve  210  as will be discussed more fully below. At a lower portion  233  of pressure relief valve  210  is defined an air director  235  including an arcuate deflector  238  having an associated opening  240  which leads into central bore  222 . 
     As shown, mounting adapter  213  includes a peripheral flange  245  formed with a plurality of mounting apertures  248 . More particularly, peripheral flange  245  extends about an adapter housing  253 . Adapter housing  253  is preferably integrally molded of plastic and includes side wall portions  254 - 257 , with side walls  254  and  256  being generally triangular in shape so as to taper upwardly. Side wall  255  is formed with an enlarged, generally rectangular opening  259 , while a bottom  260  of adapter housing  253  is open. 
     Air return housing  216  includes a peripheral plate  263  which has extending therefrom opposing side tabs, one of which is indicated at  266 . Air return housing  216  is actually defined by an enlarged body section  271  which extends from plate  263  and leads to a tapered body section  272 . Preferably, air return housing  216  is also integrally molded of plastic and defines an internal passage generally indicated at  275 . 
     Pressure relief system  200  is preferably mounted at an upper rear portion of fresh food compartment  43  of refrigerator  2 . More specifically, through an upper right rear portion of fresh food compartment  43  and cabinet shell  38  is provided a passage  290  (see FIG. 3) within which main body portion  220  of pressure relief valve  210  is positioned prior to the injection of foam insulation for cabinet shell  38  such that pressure relief valve  210  is mounted in situ. Passage  290  is generally circular but includes a flat section (not shown) to align with peripheral flat  224  to assure proper positioning of air director  235 . In any case, pressure relief valve  210  is fixed in position with truncated conical port  228  extending above cabinet shell  38  behind access panel  32 , while arcuate deflector  238  is positioned in fresh food compartment  43 . As shown in FIG. 3, arcuate deflector  238  is actually arranged with opening  240  being exposed to rear wall  44 . On the other hand, mounting adapter  213  is secured to cabinet shell  38  with truncated conical port  28  leading to and sealing about opening  261 . That is, peripheral flange  245  of mounting adapter  213  rests upon cabinet shell  38  and is secured thereto with mechanical fasteners (not shown) extending through apertures  248  and into cabinet shell  38 . In addition, air return housing  216  is attached to mounting adapter  213 , with tabs  266  extending behind side wall  255 . Therefore, internal passage  275  is in fluid communication with bore  222  and preferably opens laterally of refrigerator  2 . 
     With this arrangement, fresh food compartment  43  will be fluidly connected to the environment surrounding refrigerator  2 , at least when check valve  231  is open. In accordance with the invention, check valve  231  will automatically open when the differential pressure between inside and outside of refrigerator  2  is greater than a sealing force associated with check valve  231 . When this occurs, an equalization process will be performed. In this way, the force needed to open either of doors  6  or  10  will be maintained substantially constant. As indicated above, air director  235  opens toward rear wall  44  against a metal liner (not labeled) of fresh food compartment  43 , which will generally be the warmest zone in refrigerator  2 , for moisture condensation purposes. In addition, internal passage  275  of air return housing  216  is preferably provided with a flexible membrane  280 , such as a MYLAR or a polymeric sheet, (see FIG. 3) adjacent opening  259  for filtering purposes. In any case, to relieve the pressure differential, pressure relief assembly  200  defines a duct which serves as a pathway for pressure relief from one chamber of refrigerator  2  to the surrounding environment. By incorporating check valve  231 , the pressure relief function is performed automatically as needed. 
     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, although the most preferred form of the invention incorporates the structure and arrangement set forth above, it would be possible to incorporate other valve structure to perform the pressure equalization function and/or reposition pressure relief assembly  200 . In any event, the invention is only intended to be limited by the scope of the following claims.