THERMOELECTRIC REFRIGERATED SECONDARY SHELF

BACKGROUND OF THE INVENTION

The present invention relates to cooling of enclosed spaces and, more particularly, to thermoelectric cooling of structures therein. Foods that require cooling to be kept fresh are often offered for sale in food stores by displaying such foods in the interiors of glass front, cooled display cases. The food that is being offered is made visible to customers through the glass front thereof by displaying same in the interior space of the case on one or more shelves in that case. The cooling in this interior space has commonly been provided by a cyclic refrigeration system based on the vapor-compression cycle of a circulating refrigerant with the system evaporator coils positioned along shelves or overhead, or both, in the display case, and often accompanied with an air circulation fan.

More recently, thermoelectric cooling has been used with portable coolers and various electronic devices, and in other cooling arrangements. Thermoelectric cooling devices are entirely solid state devices using the Peltier effect in semiconductor or semimetal materials to convert controlled electrical currents into corresponding thermal gradients between an input surface of the device module, thermally coupled to that which is to be cooled, and an output surface thereof thermally coupled to some sort of heat sink. Such output surface coupling adds to the difficulty in providing a display case shelf remote from the display case interior space bottom which is the convenient location to provide such a heat sink structure, and therefore there is a desire for a more convenient thermoelectric cooling arrangement for a display shelf remote from the display case interior space bottom.

BRIEF SUMMARY OF THE INVENTION The present invention provides an enclosure cooling system for cooling an interior space in an enclosure having therein a first shelf with a side thereof adjacent to an evaporator coil in a cyclic refrigeration system with a second shelf positioned in the interior space apart from and on a side

of the first shelf opposite that to which the evaporator coil is adjacent. A thermoelectric cooling module is affixed and thermally coupled to the second shelf.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a cross section side view of a representation of a cooled display case embodying the present invention, and

Figure 2 shows a top view of an alternative representation of the present invention.

DETAILED DESCRIPTION A cooled display case, 10, is shown in a cross section side view in Figure 1 , and has a base or bottom shelf, 11 , for supporting cooled items offered for sale such as food displayed behind a pair of adjacent glass sheets, 12, at the front of case 10 covering the interior space thereof. Shelf 1 1 of thermally conductive material is supported in the interior of case 10 from underneath at opposite sides thereof in Figure 2 by shelf supports, 13. A companion evaporator coil, 14, as a part of the case cyclic refrigeration system, is supported on the bottom interior surface of case 10 adjacent to bottom shelf 1 1 with a fan, 15, adjacent thereto to circulate cooled air through the interior space of case 10 as is conventional. Shelf 11 relatively near the bottom of the interior space of case

10, even with cooled items thereon being offered for sale, typically leaves substantial room above such displayed items so that one or more additional shelves can be added there remote from the bottom of the interior space of case 10 and shelf 11 to provide additional display support for offering further items for sale. The cooling of such items has usually been by use of an overhead gravity evaporator coil in the case refrigeration system or just by directing some of the cooled air circulated by fan 15 over the added shelf or shelves and the items displayed thereon.

A shelf, 16, of thermally conductive material, is shown added in Figure 1 in the interior space of case 10 above shelf 11 supported on shelf supports, 17, and positioned there remote from the bottom of the interior

space of case 10 and shelf 11. A thermoelectric cooling module, 18, is shown in that figure affixed to, and thermally coupled at its input surface to, the underside surface of added shelf 16 to form a heat sink for items such as food supported thereon. Each module 18 is also appropriately interconnected to the electrical power supply and control system provided for case 10, and added shelf 16 is easily disconnected at the mating electrical plug and removed from the case 10 interior space with module 18 affixed thereto. The output surface of each thermoelectric cooling module 18 has a finned heat sink structure, 19, of a thermally conductive material affixed and thermally coupled thereto. Fan 15 circulates air cooled by evaporator coil 14 over finned heat sink structure 19 to cool same by forced convection and the output surface of module 18. Alternatively, a heat sink structure thermally coupled to the outside of a side wall of case 10, perhaps supported on supports 17, could be thermally coupled to the output surface of module 18 to provide sequential heat sinking thereto. In a case 10 with sufficient room above shelf 11 , other shelves cooled in the manner of shelf 16 could also be added.

The better thermal coupling between the items displayed and cooled on shelf 16 and the heat sink formed by that shelf and module 18 to conduct heat away from those items better preserves them along with smaller energy consumption in doing so. Further, the degree of cooling on each of shelves 11 and 16 can differ because of the different cooling source arrangements for each. The providing of such differing cooling zones can be provided to a finer degree along a shelf of the type used for shelf 16 by segmenting it into separately cooled parts such as is shown for a segmented shelf, 16N, in the top view thereof in Figure 2. That shelf is shown segmented along its length into separate parts, 16NN, each again of a thermally conductive material, by intervening thermally nonconductive spacers, 16NNN. Each of shelf parts 16NN has a theremoelectric cooling module 18 affixed and thermally coupled to the underside surface of each (shown in the center of the shelf part although this positioning need not be

the one used), and which modules can be operated at a different heat transfer rates to thereby cool the shelf part to which each is affixed to a temperature that can differ from that of the others.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.