Patent Publication Number: US-6698222-B2

Title: Removable food support element in a refrigerator with means for setting the temperature of the compartment in which it is positioned, and a refrigerator containing such a compartment

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a food support element in a refrigerator, in accordance with the introduction to the main claim. The term “refrigerator” used herein means both refrigerated cabinets in which the temperature is normally higher than 0° C., and freezers in which the temperature is maintained below 0° C. 
     In a refrigerator (static or forced-air) it is very important to correctly determine the temperature of each of its preservation or freezer compartments in order to obtain optimum preservation of the foods contained therein. 
     2. Description of the Related Art 
     Various devices are known for enabling said determination, these devices generally measuring said temperature in correspondence with a wall of said compartment or in correspondence with a conduit through which air is fed into the compartment (in the case of a forced-air refrigerator), or indirectly by measuring the evaporator temperature. Although enabling functional monitoring of the temperature in the refrigerator compartment, these devices do not enable the actual temperature within the compartment to be measured or to be maintained at the desired optimum value within the compartment on the basis of the foods present therein. In this respect, this temperature is set by the user by operating an appropriate control associated with a structural part of the refrigerator (compartment wall or door, for example), this setting being maintained by measuring the obtained temperature using the aforesaid known devices, this measurement never however being taken directly at a point in the interior of said compartment, i.e. between its walls where the foods are present, with obvious drawbacks (for example measurement inaccuracies or the need for complex systems for processing the temperature information obtained for example in proximity to a wall in order to define the temperature present within the compartment). 
     SUMMARY OF THE INVENTION 
     An object of the present invention is therefore to provide a removable refrigerator element of the aforesaid type which enables a temperature to be set, or enables a class of foods to be set to which a determined temperature range corresponds, and which is to be obtained and possibly maintained within the refrigerator compartment or within a particular region thereof. 
     Another object is to provide an element which is reliable and easy to use. 
     A further object is to provide an element which, in a refrigerator or in a forced-air freezer, enables a particular temperature to be maintained within that particular region of the refrigerator compartment in which the element is positioned, on the basis of the type of food positioned on the element. 
     These and further objects which will be apparent to the expert of the art are attained by an element in accordance with the accompanying claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be more apparent from the accompanying drawing, which is provided by way of non-limiting example and in which: 
     FIG. 1 shows schematically one embodiment of a shelf according to the invention inserted into a refrigerator compartment; 
     FIG. 2 is a perspective front view of the shelf of FIG. 1; and 
     FIG. 3 is a schematic diagram of an electrical/electronic circuit enabling the temperature to be set within the interior of the compartment of FIG. 1 in which several shelves according to the invention are present. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to said figures, a refrigerator is shown schematically in FIG. 1, where it is indicated by  1 . The refrigerator can be of the known static or forced-air type. 
     In the example. the refrigerator is an upright refrigerator and comprises an internal compartment  2  having opposing lateral walls  3 ,  4  and an end wall or shoulder  5 . Usual supports (not shown) are present on the lateral walls to support a shelf  6  formed in accordance with the invention. 
     The shelf  6  comprises means  10  to enable the internal temperature of the compartment  2  to be set (or a temperature range corresponding to a determined food category to be set) and possibly to be maintained. These means  10  cooperate with the control means  11  controlling the operation of the refrigerator  1 , in order. to control and regulate, on the basis of the temperature setting obtained by the setting means, the operation of a usual refrigeration circuit schematically shown in FIG.  1  and indicated by  12 . 
     More specifically, the shelf  6  comprises a body  15  presenting lateral faces  16  and  17  to face the walls  3  and  4  of the compartment  2 , a front face  18  and a rear face  19 . The shelf  6  presents a flat surface  20  for supporting foods. According to the invention, the body  15  contains the setting means  10  associated with operating means  21  positioned preferably on the aforesaid front face  18 . These means for setting the internal temperature of the compartment  2  are an electrical and/or electronic circuit  22  suitably inserted into the body  15 , and can be of active type (i.e. self powered for example by batteries) or of passive type. 
     In the figures the circuit  22  is an electrical circuit of passive type defined by an RLC resonant circuit and comprising an inductor  23  positioned in correspondence with the lateral face  16  of the body  15  of the shelf  6  and a plurality of capacitors (for example three, as in the figures where they are indicated by  26 ,  27  and  28 ) of various capacitances. Each capacitor is connected on one side to an electrical line  30  connected to one end of the inductor  23 , and on the other side to a change-over switch ( 31 ,  32  and  33  respectively) arranged to connect each capacitor to a second electrical line  35 ,  36  and  37  respectively, connected to an electrical branch  38  connected to the other end of the inductor  23 . 
     Using the operating means  21 , a different change-over switch can be activated to connect the corresponding capacitor to the inductor in such a manner as to modify the resonance frequency of the circuit  22 . 
     The operating means  21  can be defined by a plurality of pushbuttons P 1 , P 2 , P 3  and P 4  (FIG. 2) connected to the various capacitors and which, when pressed, result in the selection of a temperature suitable for preserving different foods. For this purpose, each pushbutton carries a symbol corresponding to a particular food. Alternatively, the operating means  21  can be defined by a slidable selector  39  movable along the face  18  of the body  15  of the shelf  6 , or by a slidable reed relay, in which case the selector  39  carries a magnet  40  which on sliding in front of the change-over switch defined by a relay, closes it onto the corresponding electrical line. This results in the selection of a particular capacitance for the circuit  22  and hence the selection of a particular resonance frequency. Hence a respective desired temperature within the compartment  2  can be made to correspond to each frequency variation of the circuit  22 , this temperature being selected for example via the selector  39 . 
     To enable the circuit  21  to operate, an inductor  41  is positioned in that wall  3  of the compartment  2  which faces the face  16  of the shelf body  15 , and is connected to an oscillating circuit  42  connected to the refrigerator control means  11 , for example a microprocessor circuit. On powering the oscillating circuit  42 , of which the inductor  41  forms part, the circuit  21  is activated, so that each variation in the resonance frequency of said circuit  21  (obtained in the aforesaid manner) is noted as a variation in the resonance of the circuit  42 ; this is then determined by the control circuit or means  11  which, on the basis of the variation, act on the refrigeration circuit  12 . 
     Specific reference will now be made to FIG. 3 showing a plurality of shelves  6  cooperating with an electrical/electronic circuit which determines their resonance frequency variation and on the basis thereof acts on the refrigeration circuit  12 . If the embodiment of FIG. 3 is used in a forced-air refrigerator, a particular temperature on each shelf of the refrigerator compartment  2  can be obtained by adjusting in known manner the usual members for modifying the feed of refrigerated air into the various regions of the compartment  2 . In this case the shelves  6  are constructed of thermally insulating material. 
     The use of the invention will now be described with reference to FIG.  3 . 
     It will be assumed that the uppermost shelf  6  of FIG. 3 is to be used. The other shelves will be assumed not to be in use or, if present in the compartment  2 , not to be used for setting a local temperature within the refrigerator compartment  2 . 
     As shown in FIG. 3, the control circuit  11  (for example a microprocessor) is connected to the control voltage generator or sweep generator  50 , connected to the oscillator  42  which operates with controlled voltage. This latter is connected to a switching element  53  which selects the appropriate inductor  41  for interrogating a determined shelf. 
     On powering the circuit  42 , of which the inductor  41  forms part, and varying the capacitance of the resonant circuit  21 , the resonance frequency of the oscillator undergoes, as stated, a variation which is determined by a usual signal sensor  55  (for example a dip catcher), and is therefore determined by the circuit  11 . On the basis of this determination, corresponding to the selection of a particular temperature within the compartment  2 , the circuit  21  acts on the refrigeration circuit  12  to obtain the desired temperature within the compartment  2  (in correspondence with the shelf  6 ). 
     If several shelves  6  are present and “active” within the refrigerator, for example a forced-air refrigerator, any signal variations of the corresponding inductor  41  are discriminated by the control circuit  11  which, by directly operating the switching element, is always able to recognize which inductor has been the origin of the signal generated by the oscillator  42 . On the basis of this determination, the circuit  11  can vary the temperature of that portion of the compartment  2  comprising the shelf  6  in question. 
     In a further embodiment of the invention, any deviation in the actual temperature from that set for each shelf  6  of the invention can be determined directly by the circuit  11 , as this temperature variation results in a proportional variation in the capacitance of the capacitor selected by the circuit  21  and hence a variation in the resonance frequency of said circuit (determined by the control circuit  11 ). This circuit acts on the refrigeration circuit  12  on the basis of this determination. 
     Two embodiments of the invention have been described. Others can however be devised in the light of the present invention. For example, as stated, the circuit  22  can be of active type and comprise remote connection means (for example of radio-frequency, or other type) able to dialogue with the control means  11  in order to “inform” these latter of the temperature selected by the user for the shelf  6 . Alternatively, the circuit  22  can be of the described type, but self-powered and cooperating with a device (passive, of inductor type) connected to the means  11  and not comprising the oscillator  42 , the generator  50  or the sensor  55 . Moreover, although the described examples refer to a shelf, the circuit  22  can also be provided on a food containing drawer (for example, as in the case of upright freezers).