Abstract:
A spaced saving fruit chiller is adapted to be mounted under a covered or horizontal surface or placed in a corner on a counter. The interior of the container is cooled by a forced air flow utilizing a Peltier thermoelectric device, one wall of the container forming a wall of the air flow duct system and containing both the air inlet holes to the container and the air outlet holes from the container into the duct system.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a device for chilling fresh fruit and other fresh food products and, more particularly, to an improved under-counter fruit chiller utilizing a Peltier effect thermoelectric device. 
     Thermoelectric devices operating in accordance with the well know Peltier effect have been used as cooling/heating devices for many years. Such a thermoelectric device comprises an array of semiconductor couples connected electrically in series and thermally in parallel. The semiconductor couples are sandwiched between metalized ceramic substrates. When DC electric current is applied in series to the thermoelectric device, it acts as a heat pump with heat being absorbed on the cold side, thereby cooling it, while heat is dissipated at the other side. Reversing the current causes the direction of heat flow to be reversed. Attaching a heat sink and a cold sink to the respective hot and cold sides may enhance the efficiency of the thermoelectric device. 
     Peltier effect devices have long been used to provide coolers and/or heaters for keeping foods fresh or for warming foods for serving. It has also been found and is well known to use forced-air convection to aid in heat transfer. A small electric fan is typically used to circulate air past the cold sink and into and through a container for the food, while another fan moves ambient outside air across the heat sink to dissipate heat from it. 
     Although chillers for fresh fruit and other perishable food products are well known in the art, the market success of such devices has been limited. There appear to be a number of reasons for this lack of market success. One is the cost and heat transfer efficiency of the solid state thermoelectric modules. In addition, the need to provide circulation of cool air to attain the greatest cooling efficiency has led to complex duct systems which add substantially to the cost of the containers, typically made of molded plastic materials. A long air circulation duct system also results in heat loss and pressure drop, both of which decrease the efficiency or add to the product cost. Another issue with prior fruit chillers is the utilization of counter space. Limited counter space availability in current homes can restrict the purchase of additional counter top appliances. The fruit chiller of the current invention utilizes kitchen space otherwise underutilized. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a chiller for fresh fruit or other perishable food products utilizes a construction which optimizes a cooling air flow and thus heat transfer efficiency with a container construction that is less expensive to manufacture and permitting the use of a relatively smaller thermoelectric module. Thermoelectric modules of increased efficiency, such as disclosed in U.S. Pat. No. 5,448,109, are particularly suitable for use in the fruit chiller of the subject invention. 
     In one overall embodiment, the food chiller of the present invention is mounted under a cabinet or other overhanging horizontal surface and comprises a housing for mounting a Peltier effect thermoelectric module sandwiched between a cold sink and an opposite heat sink. The housing also defines a downward facing duct system that includes a cool air supply duct in heat transfer communication with the cold sink, a return air duct, and a cool air circulation fan in the cooling duct system to circulate air therethrough. 
     A food container portion is adjacent the housing and contains enclosing sidewalls and is openable from the housing for retrieval of the food. The food container portion has therein a plurality of inlet and outlet holes in a wall that completes the duct system. 
     In one embodiment the food container is slidably attached to the housing. Sliding the food container relative to the housing allows access to the food contained therein. 
     In another embodiment the food container is pivotally mounted to the housing. Pivoting the food container away from the housing allows access to the food contained therein. 
     In another overall embodiment, the food chiller of the present invention is located on a counter surface in the corner of two intersecting walls and comprises a housing for mounting a Peltier effect thermoelectric module sandwiched between a cold sink and an opposite heat sink. The housing also defines a lateral facing duct system that includes a cool air supply duct in heat transfer communication with the cold sink, a return air duct, and a cool air circulation fan in the cooling duct system to circulate air therethrough. 
     A food container portion is adjacent the housing and contains enclosing sidewalls and is openable from the housing for retrieval of the food. The food container portion has therein a plurality of inlet and outlet holes in a wall that completes the duct system. 
     The food container portion is normally such that cooling air is continuously recirculated. In one embodiment, however, an outside ambient air supply conduit communicates with the cooling duct system and includes a metering device to admit a controlled flow of outside air to assist in purging the cooling duct system of ethylene gas and other ripening by-products of fruit. The metering device may comprise a small diameter tube connected to the duct system upstream of the fan. 
     To help maintain the interior temperature of the container, a removable insulating sleeve may be inserted into the container. The sleeve is shaped to conform to the interior of the enclosing sidewall. The removable cover may also be provided with an insulating liner. 
     Various arrangements of partitions may be placed within the container to divide the container into different temperature zones by varying the flow of cooling air through the zones. Such partitions may be vertically disposed to extend upwardly from the container bottom wall or may be horizontally disposed and attached, for example, to a central tower or to the container sidewall. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the general arrangement of the under-counter fruit chiller of the subject invention. 
     FIG. 2 is a perspective view of the fruit chiller of FIG. 1 cut vertically in half for viewing of the interior components. 
     FIG. 3 is a vertical section through the fruit chiller shown in FIG.  1 . 
     FIG. 4 is a detailed view of the section of FIG.  3 . 
     FIG. 5 is a perspective view of the food container portion of the fruit chiller of FIG.  1 . 
     FIG. 6 is a perspective view of the fruit chiller of FIG. 1 with the food container portion opened for access to the food/fruit. 
     FIG. 7 is a perspective view of an alternate embodiment of the fruit chiller cut vertically in half for viewing of the interior components. 
     FIG. 8 is a vertical sectional detail of the alternate embodiment of the fruit chiller of FIG.  7 . 
     FIG. 9 is a perspective view showing the general arrangement of an on-counter embodiment of the fruit chiller of the subject invention. 
     FIG. 10 is an additional perspective view, cut vertically in half showing the general arrangement of the fruit chiller of the subject invention. 
     FIG. 11 is a perspective view of the fruit chiller of FIG. 9 cut vertically in half for viewing of the interior components. 
     FIG. 12 is a vertical section through the fruit chiller shown in FIG.  10 . 
     FIG. 13 is a detailed view of the section of FIG.  12 . 
     FIG. 14 is a perspective view of an alternate embodiment of the fruit chiller cut vertically in half for viewing of the interior components. 
     FIG. 15 is a vertical section through the alternate embodiment of the fruit chiller of FIG.  14 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, there is shown a fruit chiller  14  in accordance with one embodiment of the present invention. The fruit chiller includes a housing  1  for mounting under a horizontal surface, such as a kitchen cupboard. There is space inside housing  1  for housing various components of the cooling system, which will be described in detail herein. A removable container  2  is adjacent the housing  1 . Access to the stored food is provided by sliding open the food container portion  2  as shown in FIG.  6 . Alternately food container  2  could be pivotally mounted to housing  1 . Referring to FIGS. 2 through 4, there are a plurality of holes  4  in container  2  for distributed flow of the cold air into the container. Holes  5  provide a return path for outlet of the air from the container. Upon passing through holes  5 , the air is again cooled and recirculated through holes  4 . Holes  4  and  5  are in upper wall  6  of food container  2  and are shown in FIG.  5 . While this is a preferred embodiment it is also possible to reverse the airflow thus using holes  5  as inlet ports to the container and holes  4  as return air ports. The housing  1  and container  2  may both be made of injection molded plastic materials. The housing  1  is preferably opaque and the container  2  transparent. 
     The housing  1  defines an ambient air chamber  16  defined generally by housing side walls  17 , housing baffle plate  13  and the underside of the cabinet or cupboard surface that the housing is mounted to. Slots  15  provide openings for entry of ambient cooling air into and out of chamber  16 . 
     The container  2  and the food products contained therein are cooled with thermoelectric module  12  utilizing the well-known Peltier effect. The thermoelectric module  12  is mounted in the base baffle plate  13  and positioned generally horizontally in the plane of baffle plate  13 . By applying a DC current to the module, heat will be absorbed at one face (in this case the lower side of  12 ), thereby cooling it. Heat will be dissipated at the other face of the module (in this case the upper side of  12 ), thereby heating it. As is also well known in the prior art, a cold sink  10  is attached to the lower face and a heat sink  11  is attached to the upper face of the module. The cold sink  10  is typically made of aluminum and includes a flat base  18  and a series of closely spaced fins  19 . Similarly, the heat sink  11  includes an aluminum base  20  and integral closely spaced fins  21 . The heat rejected by the operating thermoelectric module  12  at the heat sink  11  is dissipated by a flow of ambient air through the ambient air chamber  16 . 
     The space  8  between baffle plate  13  and the food container wall  6  contains cold sink  10  and constitutes a downward facing duct system that is in fluid communication with the container interior  24  via air inlet holes  4  and air outlet holes  5 . A fan  9  draws air in through holes  5 . As the air is exhausted from the upper portion of fan  9  it passes over cold sink  10 , into duct system  8  and reenters the container interior  24  via holes  4 . Thus the air within container interior  24  is recirculated and cooled. 
     Ripening fruit is known to emit ethylene gas and other by-products of organic decomposition. It may be desirable to exhaust these gasses by regular or periodic replacement of the cooling air recirculating within the container interior  24 . Referring particularly to FIGS. 7 and 8, an ambient air conduit  29  comprising a small diameter metering tube extends through the side wall of the food container into adjacent holes  5  where a small volume flow of ambient outside air is drawn in by the cold sink fan  9  and mixed with the recirculated cooling air. As shown, the ambient air conduit  29  opens adjacent holes  5  just upstream of the inlet to the fan  9 . It is believed, however, that the conduit could connect to the duct system at another location therein. The inflow of ambient air may be regulated with the use of an optional valve  30  at the inlet end of the conduit  29 . To provide for the corresponding exhaust of ethylene and other gaseous by-products, it is preferred to provide a small leak between the container  2  and the housing  1 , however, a manually adjustable vent slot may also be used. The slot could be located in either the wall of the housing  2  or in the housing baffle plate  13 . 
     In FIG. 9, there is shown an alternate form of the fruit chiller  114  in accordance with another embodiment of the present invention. The fruit chiller includes a housing  101  for resting on a counter in the corner of two intersecting walls. There is space inside housing  101  for various components of the cooling system, which will be described in detail herein. A container  102  is adjacent the housing  101 . Access to the stored food is provided by opening door  103 . Referring to FIGS. 10 through 13, there a plurality of inlet holes  104  in container  102  for distributed flow of the cold air into the container. Holes  105  provide a return path for the air exiting the container. Upon passing through holes  105 , the air is again cooled and discharged through holes  104 . Holes  104  and  105  are in wall of food container  102  and are shown in FIG. 12 and 13. While this is a preferred embodiment it is also possible to reverse the airflow thus using holes  105  as inlet ports and holes  104  as outlet air ports. The housing  101 , container  102  may all be made of injection molded plastic materials. The housing  101  is preferably opaque and the container  102  and door  103  transparent. 
     The housing  101  defines an ambient air chamber  116  defined generally by housing sidewalls  117 , housing top wall  118  and housing baffle plate  113 . Feet  115  of housing  101  provide an opening at the. bottom for inlet for ambient cooling air and slots  135  provide exits for the ambient cooling air out of chamber  116 . 
     The container  102  and the food products contained therein are cooled with thermoelectric module  112  utilizing the well-known Peltier effect. The thermoelectric module  112  is mounted in the base baffle  113  and positioned generally vertically in the plane of baffle  113 . By applying a DC current to the module, heat will be absorbed at one face, thereby cooling it. Heat will be dissipated at the other face of the module, thereby heating it. As is also well known in the prior art, a heat sink  111  is attached to the hot face and a cold sink  110  is attached to the cold face of the module. The cold sink  110  is typically made of aluminum and includes a flat base and a series of closely spaced fins. Similarly, the heat sink  111  includes an aluminum base and integral closely spaced fins. The heat rejected by the operating thermoelectric module  112  at the heat sink  111  is dissipated by a flow of ambient air through the ambient air chamber  116 . 
     The space  108  between baffle  113  and the food container wall  106  encloses the cold sink  110  and constitutes a laterally facing duct system that is in fluid communication with the container interior  124  via holes  104  holes  105 . A fan  109  draws air in through holes  105 . As the air is exhausted from fan  109  it passes over cold sink  110 , into duct system  108  and reenters the container interior  124  via inlet holes  104 . Thus the air within container interior  124  is recirculated and cooled. 
     Ripening fruit is known to emit ethylene gas and other by-products of organic decomposition. It may be desirable to exhaust these gasses by regular or periodic replacement of the cooling air recirculating within the container interior  124 . Referring particularly to FIGS. 14 and 15, an ambient air conduit  129  comprising a small diameter metering tube extends through the side wall of the food container into adjacent holes  105  where a small volume flow of ambient outside air is drawn in by the cold sink fan  109  and mixed with the recirculated cooling air. As shown, the ambient air conduit  129  opens adjacent holes  105  just upstream of the inlet to the fan  109 . It is believed, however, that the conduit could connect to the duct system at another location therein. The inflow of ambient air may be regulated with the use of an optional valve  130  at the inlet end of the conduit  129 . To provide for the corresponding exhaust of ethylene and other gaseous by-products, it is preferred to provide a small leak between the container  102  and the door  103 . 
     As indicated previously, the thermoelectric module  12  is normally configured so the outer face is cold while the inner face is hot. Because reversal of the polarity of the supplied current to the thermoelectric module causes the direction of heat flow to be reversed, the fruit chillers of either of the embodiments described herein may also be utilized to warm the fruit to promote or enhance ripening. In this alternate configuration the inner face of the thermoelectric module  12  is hot while the outer face is cold. 
     Certain fruits may often be purchased in a green or semi-ripe condition. One example is bananas which are often purchased in some semi-ripe condition and allowed to ripen in the open air. By reversal of the supplied current to the thermoelectric module  112 , a green or semi-ripe fruit may be ripened more quickly by warming and, when ripe, preserved for a longer time by again reversing the current to provide a cooling air supply to the container  124 . 
     In general, temperature control is an excellent, and by far the best means, of controlling ripening in fruit. As discussed above, warming may be used to enhance and promote ripening of green or semi-ripe fruit, but after the fruit has ripened, cooling is the best means available to slow the biological ripening processes and preserve the fruit for a longer period of time. 
     The direction of heat transfer of the thermoelectric module  112  can be reversed as mentioned above. The level of heating and cooling can also be controlled by control of the level of supplied current and voltage. In this manner, the user may, for example, select a set point to ripen fruits at a desirable rate or, conversely, a cooling set point to maintain ripened fruit at a temperature found to make the fruit most palatable. Other cooling or warming strategies may also be utilized, either with manual settings by the user or by using programmed microprocessor control.