Abstract:
A storage device for the preservation of oxidizable materials is provided. The storage device includes a storage chamber enclosing a storage space where oxidizable materials may be placed, the storage chamber having at least one fluid passage therethrough from the storage space to atmosphere. At least one differentially permeable membrane is disposed within at least one of the fluid passages, the differentially permeable membrane allowing at least one selected gas to pass therethrough while inhibiting at least one other selected gas from passing therethrough. An evacuator evacuates oxygen from within the storage chamber through at least one of the fluid passages to the atmosphere such that the level of oxygen within the storage chamber is reduced relative to the level of oxygen in the atmosphere.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of, under 35 U.S.C. 119(e), U.S. Provisional Patent Application No. 60/275,397, filed Mar. 13, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to a storage device, and more specifically to a long-term storage device for oxidizable materials which controls the gaseous content of a storage volume of the device in order to prolong storage life, allow storage of currently difficult-to-store materials and to inhibit the ripening and/or deterioration of certain foods.  
         BACKGROUND OF THE INVENTION  
         [0003]    Refrigerated devices are well known and widely utilized to increase the storage life of items to be stored, such as food items. As an example, a refrigerator commonly used in most households in the United States increases the storage life of many foods by maintaining the temperature well below room temperature, thereby slowing the natural ripening and oxidation processes. However, such devices suffer from a number of disadvantages, including complexity, weight and cost.  
           [0004]    Moreover, refrigerated devices can be noisy and generate a great amount of heat, which may be undesirable in many circumstances. Furthermore, refrigeration devices are generally not energy efficient, and thus such devices are typically costly to operate and environmentally unfriendly. Furthermore, refrigeration devices may not be appropriate for storing all food items (e.g., apples may lose their taste when cold, bananas may turn black, etc.). Another problem with refrigeration devices is that they may not be appropriate for storing many non-food items (e.g., documents, stamps, coins, etc.) due to moisture problems.  
           [0005]    Another type of storage device which has been developed is a vacuum storage device, which operates by creating a vacuum within a storage volume of the device in order to remove oxygen therefrom, and extend the storage life of oxidizable materials. Although such devices obviate some of the disadvantages of refrigeration devices (i.e., the problems associated with storing certain food items in a cold environment and the moisture problems), vacuum devices do not remedy a number of the other problems. Vacuum storage devices are typically even more complex, heavy and costly to produce than refrigeration devices, which is why such vacuum devices are typically used only in industrial settings. These devices are typically large and may pose a safety problem, as it has been known that persons may become trapped within such devices, and be injured or killed because of the vacuum created therein.  
           [0006]    Furthermore, the vacuum pumps used with vacuum storage devices can be noisy and are generally not energy efficient, thereby making vacuum storage devices costly to operate and environmentally unfriendly. Moreover, vacuum storage devices suffer from a number of additional disadvantages. In addition to requiring a costly vacuum pump, the storage volume itself is also costly. This is true because, due to the vacuum created, a structurally heavy storage volume is required so as to inhibit implosion or collapsing thereof due to the vacuum formed therein. Moreover, a complex and expensive sealing means is required so that the storage volume can hold a vacuum. Moreover, despite the precautions taken, there is a very real possibility that implosion may occur and/or that a vacuum may not be held.  
           [0007]    Yet another type of storage device which has been developed is an inert gas pumping system. In these devices, an inert gas environment is artificially maintained within a storage volume by pumping an inert gas, such as nitrogen, into the storage volume, thereby displacing the normal atmospheric content (including oxygen) to maintain and prolong the storage life of oxidizable items stored therein. However, these devices are typically even more costly and complex than refrigeration and vacuum systems, and are therefore generally used only to store rare documents, stamps, coins, and/or other valuable materials. A further disadvantage of these types of systems is that it is necessary to provide, and to replace on a regular basis, cylinders of inert gas, which can be costly and burdensome, and which renders such devices appropriate only for large-scale industrial use (as opposed to home use).  
           [0008]    What is desired, therefore, is a storage device for oxidizable materials which controls the gaseous content of a storage volume of the device in order to prolong storage life, to allow storage of currently difficult-to-store materials, to allow storage of non-refrigeratable foods and to inhibit the ripening and/or deterioration of certain foods without adversely affecting flavor, which is relatively simple in design, lightweight and inexpensive to produce, which operates quietly and does not generate a great amount of heat, which is appropriate for storing substantially all oxidizable food items and non-food items, which is energy efficient and therefore relatively inexpensive to operate and environmentally friendly, which does not risk implosion, and which does not require servicing and/or the replacement of components on a regular basis.  
         SUMMARY OF THE INVENTION  
         [0009]    Accordingly, it is an object of the present invention to provide a storage device for oxidizable materials which controls the gaseous content of a storage volume of the device in order to prolong storage life, to allow storage of currently difficult-to-store materials, to allow storage of non-refrigeratable foods and to inhibit the ripening and/or deterioration of certain foods without adversely affecting flavor.  
           [0010]    Another object of the present invention is to provide a storage device for oxidizable materials having the above characteristics and which is relatively simple in design, lightweight and inexpensive to produce.  
           [0011]    A further object of the present invention is to provide a storage device for oxidizable materials having the above characteristics and which operates quietly and does not generate a great amount of heat.  
           [0012]    Still another object of the present invention is to provide a storage device for oxidizable materials having the above characteristics and which is appropriate for storing substantially all oxidizable food items and non-food items.  
           [0013]    Yet a further object of the present invention is to provide a storage device for oxidizable materials having the above characteristics and which is energy efficient and therefore relatively inexpensive to operate and environmentally friendly.  
           [0014]    Still yet a further object of the present invention is to provide a storage device for oxidizable materials having the above characteristics and which does not risk implosion.  
           [0015]    Yet another object of the present invention is to provide a storage device for oxidizable materials having the above characteristics and which does not require servicing and/or the replacement of components on a regular basis.  
           [0016]    These and other objects of the present invention are achieved by provision of a storage device for the preservation of oxidizable materials. The storage device includes a storage chamber enclosing a storage space where oxidizable materials may be placed, the storage chamber having at least one fluid passage therethrough from the storage space to atmosphere. At least one differentially permeable membrane is disposed within at least one of the fluid passages through the storage chamber, the differentially permeable membrane allowing at least one selected gas to pass therethrough while inhibiting at least one other selected gas from passing therethrough. An evacuator evacuates oxygen from within the storage chamber through at least one of the fluid passages to the atmosphere such that the level of oxygen within the storage chamber is reduced relative to the level of oxygen in the atmosphere.  
           [0017]    In one embodiment, the at least one fluid passage comprises an inlet fluid passage and an outlet fluid passage. The differentially permeable membrane is disposed within the inlet fluid passage and allows at least one gas to pass therethrough while inhibiting at least oxygen from passing therethrough. The evacuator evacuates gasses, including oxygen, from within the storage chamber through the outlet fluid passage, and gasses other than oxygen replace the gasses evacuated by the evacuator by passing through the differentially permeable membrane disposed in the inlet fluid passage until the level of oxygen within the storage chamber is greatly reduced. In this embodiment, a one-way check valve is preferably disposed within the outlet fluid passage to inhibit gasses from flowing into the storage chamber through the outlet fluid passage. Most preferably, the differentially permeable membrane allows at least nitrogen to pass therethrough while inhibiting at least oxygen from passing therethrough.  
           [0018]    In another embodiment, the at least one fluid passage comprises an outlet fluid passage. The differentially permeable membrane is disposed within the outlet fluid passage and allows at least oxygen to pass therethrough while inhibiting at least one other gas from passing therethrough. The evacuator evacuates at least oxygen from within the storage chamber through the differentially permeable membrane disposed in the outlet fluid passage. Most preferably, the differentially permeable membrane allows at least oxygen to pass therethrough while inhibiting at least nitrogen from passing therethrough.  
           [0019]    In both embodiments, the evacuator preferably comprises either a fan or a compressor. The differentially permeable membrane may take any of a number of forms, including a substantially flat sheet of material or cartridge, or a substantially cylindrical hollow fiber cartridge. Preferably, a gauge is provided for monitoring the level of oxygen within the storage chamber. Most preferably, the gauge is used to selectively switch the evacuator on or off depending upon the oxygen level within the storage chamber in order to conserve energy.  
           [0020]    The invention and its particular features and advantages will become more apparent from the following detailed description considered with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a perspective view of an embodiment of a storage device for oxidizable materials in accordance with the present invention;  
         [0022]    [0022]FIG. 2 is a cross-sectional view of the embodiment of a storage device for oxidizable materials shown in FIG. 1;  
         [0023]    [0023]FIG. 3 is a cross-sectional view of a second embodiment of a storage device for oxidizable materials in accordance with the present invention;  
         [0024]    [0024]FIG. 4 is a perspective view of a third embodiment of a storage device for oxidizable materials in accordance with the present invention; and  
         [0025]    [0025]FIG. 5 is a cross-sectional view of the embodiment of a storage device for oxidizable materials shown in FIG. 4;  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    Referring first to FIGS. 1 through 3, a storage device  10  for oxidizable materials is shown. Storage device  10  includes a plurality of outer walls  12  defining a storage chamber  14 . Storage chamber  14  may be of substantially any shape, for example, square, rectangular, cylindrical, trapezoidal, cookie jar-shaped, thermos-shaped, etc., by varying the configuration of outer walls  12 , as should be readily apparent to those skilled in the art. A rectangular shape, however, is preferred for ease of construction and use, as shown in the Figures. Storage chamber  14  provides a convenient place to store oxidizable objects.  
         [0027]    Access to the interior of storage chamber  14  is provided through door  16  utilizing hinges  18  and a handle mechanism  20  which is known in the art. Any satisfactory door and handle means may be used to access the interior portion of storage chamber  14  while providing a reasonably air tight seal between the exterior and interior. As such, and because such door and handle means are known in the art, a detailed description thereof is not presented herein. However, it should be noted that it is preferable, although not necessary, that door  16  comprise substantially an entire side of storage chamber  14  and that hinges  18  are positioned accordingly, such as is the case with a typical microwave oven. This arrangement is preferable so as to allow unrestricted access to the interior of storage chamber  14 , and to allow off-gasses (which may occur particularly when fresh fruits or vegetables are stored) to exit storage chamber  14  through door  16  when opened.  
         [0028]    An inlet opening  22  and an outlet opening  24  pass through outer walls  12  in order to create inlet fluid passage  26  and outlet fluid passage  28  respectively between storage chamber  14  and the atmosphere. Inlet opening  22  and outlet opening  24  may pass through the same outer wall  12 , or through different outer walls  12  (as shown in the Figures). Moreover inlet opening  22  and outlet opening  24  may comprise a single opening (as shown in FIG. 2 with respect to outlet opening  24 ) or a plurality of openings (as shown in FIG. 2 with respect to inlet opening  22 ).  
         [0029]    Disposed within inlet fluid passage  26  is a differentially permeable membrane  30 . Differentially permeable membrane  30  is formed from a material which allows one or more selected gases to differentially pass therethrough, while inhibiting oxygen from doing the same. As the normal atmosphere contains almost 80% nitrogen (which does not typically deleteriously affect oxidizable materials), differentially permeable membrane  30  is preferably formed from a material which allows nitrogen to differentially pass therethrough, while inhibiting oxygen from doing the same.  
         [0030]    However, it should also be noted that differentially permeable membrane  30  may be formed from a material which allows gases other than, or in addition to, nitrogen to differentially pass therethrough. For example, if carbon dioxide would not adversely affect the oxidizable materials to be stored within storage chamber  14 , differentially permeable membrane  30  may be formed from a material which allows both nitrogen and carbon dioxide to pass therethrough, while inhibiting oxygen from doing the same.  
         [0031]    It should also be noted that differentially permeable membrane  30  may take any of numerous forms. For example, FIGS. 1 and 2 show differentially permeable membrane  30  as taking the form of a substantially flat cartridge or sheet of material for the sake of simplicity. When such is the case, a membrane holder  32  may be provided which allows differentially permeable membrane  30  to be easily slid in or out, which facilitates replacement of differentially permeable membrane  30  should such be required. Membrane holder  32  includes at least one opening  34  therein for allowing air to enter therethrough to reach differentially permeable membrane  30 . However, as will be understood by those skilled in the art, differentially permeable membranes having a substantially flat configuration are not currently widely employed.  
         [0032]    Rather, and referring specifically now to FIG. 3, differentially permeable membrane  30 ′, according to currently existing technology, preferably takes the form of a cylindrical cartridge or the like. Such a cartridge typically includes an inlet  100  for receiving gasses to be differentially separated, an outlet  102  for passing through the selected gas or gasses which are allowed to pass, and a vent  104  for returning the selected gas or gasses which are not allowed to pass to the original volume of gasses (whether it be the atmosphere or the storage chamber  14 ). Located within the cartridge are a plurality of hollow fibers  106  which act to separate and direct appropriate gasses to either outlet  102  or vent  104 . Because such cartridges are known to those skilled in the art, and readily available on the market (for example, from MEDAL L.P. of Newport, Del.), a more detailed description of such cartridges is not presented herein. As should be understood by those skilled in the art, other configurations for differentially permeable membrane  30  are also possible.  
         [0033]    Disposed adjacent to outlet opening  24  within outlet fluid passage  28  is an evacuator  36 , for drawing gases out of storage chamber  14 . Evacuator  36  may take the form of, for example, a fan, a compressor or a pump. However, it should be understood that a relatively powerful compressor, such as is used in refrigeration cycle systems, is not required. It should also be understood that it is not necessary for there to be a strong vacuum maintained within storage chamber  14 . All that is necessary is an evacuator  36  powerful enough to remove gasses from storage chamber  14  and allow the selected gas or gasses (e.g., nitrogen, carbon dioxide, etc.) to differentially pass through differentially permeable membrane  30 . A housing  38  may be provided to house evacuator  36 , which housing includes at least one opening  40  passing therethrough in order to allow gasses evacuated from storage chamber  14  to be passed to the atmosphere.  
         [0034]    A gauge or oxygen meter  42  may optionally be provided to monitor the percentage of oxygen content within storage chamber  14 . Although not required, such a gauge  42  may allow a user or manufacturer to verify that the oxygen content of storage chamber  14  is within a desired range. Moreover, gauge  42  may be used to selectively switch evacuator  36  on or off depending upon the oxygen content of storage chamber  14  in order to conserve energy. For example, when the oxygen content within storage chamber  14  is above a desired value, evacuator  36  may be turned on, and when the oxygen content within storage chamber  14  is below the desired value, evacuator  36  may be turned off. Alternately, evacuator  36  may continuously run.  
         [0035]    A one-way check valve  50  may also be disposed within outlet fluid passage  28  in order to inhibit oxygen-containing air from entering storage chamber  14  therethrough. As should be understood by those skilled in the art, such a check valve  50  is particularly desirable when evacuator  36  is allowed to be turned off. However, a check valve  50  may be desirable in any event, such that in the case of a power failure or the like, the evacuator is unintentionally turned off.  
         [0036]    In operation, storage device  10  operates by removing gasses from storage chamber  14  through outlet fluid passage  28 , while allowing a selected gas or gases present in the atmosphere (e.g., nitrogen, carbon dioxide, etc.) to be drawn into storage chamber  14  through differentially permeable membrane  30  located within inlet fluid passage  26 . Thus, even if storage chamber  14  initially contains some oxygen, for example, as would be introduced when door  16  is opened to gain access to storage chamber  14 , the content of oxygen within storage chamber  14  would be gradually decreased as the gasses within storage chamber  14  (which include the oxygen) are evacuated, and replaced with substantially oxygen free gasses.  
         [0037]    By employing the above-described storage device, the atmosphere within storage chamber  14  may be controlled to replace normal atmospheric content of gas (i.e., approximately 80% nitrogen and 20% oxygen) with an atmosphere with considerably less oxygen.  
         [0038]    Because storage device  10  preferably incorporates a fan, pump or simple compressor instead of a vacuum pump or refrigeration compressor, the device is more energy efficient than known refrigeration and vacuum systems.  
         [0039]    Referring again to FIG. 3, storage device  10  may further include additional optional elements to further enhance the storage capabilities thereof. For example, if storage device is to be used to store certain items, such as certain foods which benefit from moisture, a humidifier  108  may be provided to provide moisture to the gasses within storage chamber  14 . Further, a device  110  for killing undesirable microbes, such as an ultraviolet light or an anti-microbial spray, may also be provided.  
         [0040]    Referring now to FIGS. 4 and 5, another embodiment of a storage device  10 ′ in accordance with the present invention is shown. This embodiment is similar to the embodiments discussed above, with the main exception being that a differentially permeable membrane  30 ″ which allows at least oxygen to differentially pass therethrough, while inhibiting at least one gas (preferably at least nitrogen) from doing the same. In this embodiment, no inlet passage is provided, and differentially permeable membrane  30 ″ is disposed within outlet fluid passage  28 . As with the embodiments discussed above, differentially permeable membrane  30 ″ may take numerous forms, such as a substantially flat cartridge or sheet of material, or a cylindrical cartridge. A membrane holder  32 ′ may be provided which allows differentially permeable membrane  30 ″ to be easily slid in or out, which facilitates replacement of differentially permeable membrane  30 ″ should such be required. Membrane holder  32 ′ includes at least one opening  34 ′ therein for allowing oxygen (and any other gases) passing through differentially permeable membrane  30 ″ to reach the atmosphere.  
         [0041]    In operation, this embodiment of storage device  10  operates by removing oxygen from storage chamber  14  through outlet fluid passage  28 , while inhibiting a selected gas or gases initially present within storage chamber  14  (e.g., nitrogen) to be withdrawn through differentially permeable membrane  30 ″ located within outlet fluid passage  28 . Thus, even if storage chamber  14  initially contains some oxygen, for example, as would be introduced when door  16  is opened to gain access to storage chamber  14 , the content of oxygen within storage chamber  14  would be gradually decreased as it is evacuated through differentially permeable membrane  30 ″.  
         [0042]    The present invention, therefore, provides a storage device for oxidizable materials which controls the gaseous content of a storage volume of the device in order to prolong storage life, to allow storage of currently difficult-to-store materials, to allow storage of non-refrigeratable foods and to inhibit the ripening and/or deterioration of certain foods without adversely affecting flavor, which is relatively simple in design, lightweight and inexpensive to produce, which operates quietly and does not generate a great amount of heat, which is appropriate for storing substantially all oxidizable food items and non-food items, which is energy efficient and therefore relatively inexpensive to operate and environmentally friendly, which does not risk implosion, and which does not require servicing and/or the replacement of components on a regular basis.  
         [0043]    Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.