THERMOELECTRIC HOT/COLD PANS

Abstract

A container temperature control system having an inner container and a receptacle in which the inner container can be positioned. A thermoelectric based heat transfer unit is positioned in an opening in the receptacle such that an interior portion thereof is by the inner container and an exterior portion thereof is outside with heat being selectively transferable between these interior and exterior portions.

Description

BACKGROUND OF THE INVENTION

The present invention relates to cooling or heating of nested pan structures and, more particularly, to thermoelectric cooling or heating of pans nested in receptacles.

Foods that require either cooling or heating to be most acceptable for consumption, or cooled to be kept fresh, are often presented for consumption in cold pan or hot pan arrangements. In one kind of such arrangements, an inner pan (or liner pan or insert pan) with the food to be consumed contained therein is placed in an outer pan or other receptacle that has a deeper interior than that inner pan. As a result, there is a space between the outer surface of the inner pan bottom and the inner surface of the outer pan bottom, a space which has ice placed in it for cooling of the inner pan and food or, alternatively, hot water placed in it for heating same. This forms a reasonably portable food serving arrangement for positioning on serving counters or tables while also providing some degree of temperature control of the inner pan and its food contents.

In another kind of arrangement, the cooling of the pan with the food in it is provided by a cyclic refrigeration system based on the vapor-compression cycle of a circulating refrigerant with the system evaporator coils positioned along the inner pan bottom in the space between the inner and outer pans. In yet another kind of arrangement, the heating of the pan with the food in it is provided by an electrical resistive heater with its heat emanating resistive components positioned about the outside of that pan again in the space between the inner and outer pans. These various pan heating and cooling arrangements either require considerable attention in monitoring ice levels or water temperatures, and replacing same as needed by removing the inner pan temporarily to allow refilling the space (and often to also take the inner plan to the food source to replenish same), or are noisy and expensive for use with relatively small food containing pans typically used at serving counters or tables. Thus, there is a desire for convenient and economical pan cooling and heating arrangements.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a container temperature control system for a removable container having an inner container and a receptacle in which the inner container can be positioned leaving a separation space therebetween, and from which the inner container can be removed. A thermoelectric based heat transfer unit is positioned in an opening in the receptacle such that an interior portion thereof is positioned in the separation space and that an exterior portion thereof is positioned outside of the receptacle with heat being selectively transferable between these interior and exterior portions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front cross section view of a pan arrangement embodying the present invention,

FIG. 2 shows a front cross section view of an alternative pan arrangement embodying the present invention, and

FIG. 3 shows a front cross section view of an alternative pan arrangement embodying the present invention.

DETAILED DESCRIPTION

Thermoelectric cooling and heating has been used with portable coolers and heaters. Thermoelectric cooling and heating 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 or a source of heat, and an output surface thereof thermally coupled to that which is to be heated or some sort of heat sink. Whether one of the major surfaces of a thermoelectric device is an input surface or an output surface is determined by the direction of electric current supplied therethrough.

Such thermoelectric modules provide convenient and economical heating or cooling, or both, for a portable inner pan and outer pan receptacle food serving arrangements with an easily removeable inner pan, and with better temperature control and energy efficiency. These modules are positioned and supported in the outer pan receptacle without being affixed to the inner pan, and cool or heat that inner pan either convectively or conductively so as to allow that inner pan to be easily removed from the outer pan receptacle.

FIG. 1 shows a front cross section view of such an inner pan and outer pan receptacle food serving arrangement, 10. An inner pan, 11, of a thermally conductive material is provided to, for example, receive therein food and is supported in an outer receptacle, or outer pan receptacle, 12, which is in turn supported on a stand, 13. As an alternative, inner pans of other sizes can instead be used such as the alternative deeper pan, 11N, shown in FIG. 1 in dashed line form. Receptacle 12 is formed of an outer shell, 14, typically of metal, and filled in the interior thereof with a foam insulation, 15. An opening in the bottom of receptacle 12 accommodates affixed therein to the receptacle bottom wall a thermoelectric based cooling and heating unit, 16. A portion of unit 16 is in the space between inner pan 11 and receptacle 12 on one side of the receptacle bottom wall, and another portion thereof is outside of the receptacle bottom wall in the space created by stand 13 between the receptacle bottom wall and the surface (not shown) supporting stand 13. Receptacle outer shell 14 has inner pan supports, 17, on which inner pan 11 can be placed for support and from which pan 11 can be easily removed.

Thermoelectric based cooling and heating unit 16 has a thermoelectric device module, 18, with an upper thermal transfer plate, 18N, and a lower thermal transfer plate, 18NN, with the thermoelectric device portion thereof positioned therebetween, and on either side of which is provided one of a pair of foam insulation spacers, 15N. An upper finned heat transfer structure, 19, has a plate portion thereof against upper thermal transfer plate 18N and both of foam insulation spacers 15N with fins extending upward from that plate portion as does a pedestal supporting a fan, 20. A lower finned heat transfer structure, 21, has a plate portion thereof against lower thermal transfer plate 18NN and both of foam insulation spacers 15N with fins extending downward from that plate portion as does a pedestal supporting a fan, 22.

Unit 16 is also appropriately interconnected to the electrical power supply and control system provided in and for inner pan and outer pan receptacle food serving arrangement 10. Directing electrical current in one direction through the thermoelectric device portion of thermoelectric device module 18 in thermoelectric based cooling and heating unit 16 causes upper thermal transfer plate 18N to be the module input plate drawing in heat through upper finned heat transfer structure 19 from the air in the space between inner pan 11 and receptacle 12 circulated over those fins by fan 20. Correspondingly, lower thermal transfer plate 18NN is caused to be the output plate to transfer heat to the exterior of receptacle 12 through lower finned heat transfer structure 21 into the air external to arrangement 10 circulated over those fins by fan 22. Thus, in this current direction selection, inner pan and outer pan receptacle food serving arrangement 10 is caused to be a forced convection cooler to cool items contained in pan 11 through convective transfers both in the space between pan 11 and receptacle 12 and on the outside of receptacle 12. Directing electrical current in the opposite direction through the thermoelectric device portion of thermoelectric device module 18 in thermoelectric based cooling and heating unit 16 reverses the direction of heat flow along the same path just described to cause inner pan and outer pan receptacle food serving arrangement 10 to be a forced convection heater to heat items contained in pan 11.

FIG. 2 shows a front cross section view of an alternative inner pan and outer pan receptacle food serving arrangement, 10N, in which fan 20 is not used but instead an alternative upper finned heat transfer structure, 19N, is provided in a thermoelectric based cooling and heating unit, 16N, having the fins thereof directly against the bottom of inner pan 11. Thus, rather than transferring heat by forced convection in the space between pan 11 and receptacle 12, heat is transferred to or from pan 11 by conduction depending on whether the current direction through the thermoelectric device portion of thermoelectric device module 18 in thermoelectric based cooling and heating unit 16 causes heating or cooling of that pan. Alternatively, rather than using upper finned heat transfer structure 19N, just a heat transfer plate could be used without fins with the bottom of pan 11 positioned thereagainst for heat transfer by conduction through that pan and plate.

More than one of thermoelectric based cooling and heating units 16 or 16N, or even some combination of each kind, can be used in such inner pan and outer pan receptacle food serving arrangements. This is especially desirable in larger arrangements using larger, or multiple compartment, versions of pan 11. As an example, FIG. 3 shows a front cross section view of an inner pan and outer pan receptacle food serving arrangement, 10NN, in which three of pans 11 have been welded together at the adjacent edges thereof to form a larger, three compartment pan, 11NN. Correspondingly, one of three thermoelectric based cooling and heating units 16 has been positioned across from each compartment in pan 11NN affixed in a corresponding opening in the bottom wall of a modified receptacle, 12N, in the same manner as was shown in FIG. 1, although such one-to-one correspondence between multiple compartments in one inner pan and units 16 or 16 Nisn=t necessarily required. However, there could alternatively be three separate pans in the FIG. 3 structure with added wall portions in receptacle 12N that provide separate spaces below each pan and the corresponding portion of that receptacle. In that circumstance a one-to-one correspondence between multiple inner pans and one of units 16 or 16 Nis required to provide a selected temperature for each such inner pan but each of those pans could be operated at a different selected temperature including some being heated while others are cooled.

Receptacle 12N in FIG. 3 is shown without a corresponding support stand 13 which, of course, could be provided so the outer fans in units 16 could operate without interference from the arrangement supporting surface. This omission is to indicate that such inner pan and outer pan receptacle food serving arrangements as shown in the various figures, although useable with stands for portability, can alternatively be provided as built-ins to be affixed in more permanent serving counters or tables. The receptacle is affixed in such more permanent serving counters or tables thereby still leaving the inner pan or pans easily removable for purposes of replenishment or for cleaning after use.

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.

Claims

1. A container temperature control system for a removable container, the system comprising:

an inner container,

a receptacle in which the inner container can be positioned to enclose a separation space therebetween within which air can convectively circulate, and from which receptacle the inner container can be removed, and

a thermoelectric based heat transfer unit positioned in an opening in the receptacle such that an interior portion thereof is positioned in the separation space and that an exterior portion thereof positioned outside of the receptacle with heat being selectively transferrable between these interior and exterior portions.

2. The system of claim 1 wherein the inner container is formed of thermally conductive material.

3. The system of claim 2 wherein the inner container is an arrangement for holding plural types of contents separate from one another.

4. The system of claim 3 wherein there is a plurality of thermoelectric based heat transfer units positioned in corresponding openings in the receptacle with each of the plural types of contents having heat transferred with respect thereto by at least one of the plurality of thermoelectric based heat transfer units.

5. The system of claim 1 wherein the receptacle has structures therein that are thermally insulative.

6. The system of claim 5 wherein the structures are relatively rigid walls separated by foam insulation.

7. The system of claim 6 wherein supports are provided with the rigid walls on which the inner container can be supported at or near edges thereof if positioned in the receptacle.

8. The system of claim 1 wherein the thermoelectric based heat transfer unit has a thermoelectric device portion thereof positioned between a pair of heat transfer plates.

9. The system of claim 8 wherein at least one of the heat transfer plates has a plurality of fins extending outward therefrom.

10. The system of claim 9 wherein one of the heat transfer plates extends between the thermoelectric device portion and the inner container if the inner container is positioned in the receptacle.

11. The system of claim 9 wherein the heat transfer plate with fins supports a fan that can circulate air over those fins.

12. The system of claim 9 wherein both of the heat transfer plates have a plurality of fins extending outward therefrom.

13. The system of claim 11 wherein the heat transfer plates each support a fan that can circulate air over the fins thereof.

14. The system of claim 10 wherein the heat transfer plate extending between the thermoelectric device portion and the inner container is positioned has fins and supports a fan that can circulate air over those fins.