Electric heating – Inductive heating – With heat exchange
Reexamination Certificate
2002-09-25
2003-12-30
Leung, Philip H. (Department: 3742)
Electric heating
Inductive heating
With heat exchange
62, C126S246000
Reexamination Certificate
active
06670589
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat retentive food tray, and particularly a heat retentive food tray adapted to be heated by electrical induction. More particularly, the present invention relates to a heat retentive food tray with a cover, adapted to be heated by electrical induction.
2. Description of Related Art
In environments where food is prepared and cooked in a central location and distributed and served to consumers who are remotely located, such as, in hotels, aircraft and institutional settings, e.g., hospitals and nursing homes, there is often a delay between the time that the food is prepared, cooked and subsequently placed on a plate or other serving dish, and the time that the food is eventually presented to the consumer for consumption at a remote location. Accordingly, by the time the food is presented to the consumer, the food can become cold unless special measures are taken to keep the food hot. Various approaches to such meal service problems encountered in service environments, sometimes referred to as “satelliting,” have been employed in the food service and container industries.
One particular embodiment of heat retentive servers can be designed to support dishware, which in turn holds a portion of a meal that is to be kept hot. In such circumstances, the base is commonly called a “pellet” base, and the entire system, i.e., the base, dome and plate, is referred to as a “pellet system.” When a heat sink is incorporated into a server base and the base supports a food-carrying dish, or plate, the base can be referred to as a plate warmer.
In general, heat retentive servers employ convection or conduction heating in order to either heat a food service dish or heat a heat storage battery during food service operations.
U.S. Pat. No. 3,916,872 to KREIS et al., issued Nov. 4, 1975, discloses a heat storage dish comprising a central heat storage disk and an insulating member that surrounds the heat storage dish. The heat storage dish consists of a substantially circular metallic body member that may be equipped with a central opening. The heat storage dish may, for example, be heated by subjecting it to a high frequency field, thus inductively heating the heat storage dish. U.S. Pat. No. 3,557,774, issued Jan. 26, 1971 to KREIS, discloses a heat storage dish having a heat storage plate enclosed between an interior wall and an exterior wall, secured at their edges to prevent the entry of any external substance.
U.S. Pat. No. 4,776,386 to MEIER, issued Oct. 11, 1988, discloses an apparatus for cooling, storing and reheating food, using induction heating. This system includes a tray distribution system wherein a tray, which may be adapted to support, e.g., a soup tureen, a dish for meat, a hot beverage cup, a salad plate, and/or a similar plate such as a fruit dish, as well as a trough for cutlery, may be provided. A meal, supported on such a tray, can be stored in a refrigerated environment. In this system, the refrigerated cabinet in which the trays are stored includes induction coils. In practice, prior to serving, the cooling system of the refrigerator is turned off and the induction coils are activated to supply heat to the appropriate areas in the tray. U.S. Pat. No. 4,881,590 to MEIER, issued Nov. 21, 1989, discloses a similar system.
U.S. Pat. No. 3,734,077 to MURDOUGH et al., issued May 22, 1973, discloses a server that includes a recess in order to receive a plate. The server comprises an upper shell, a lower shell, a heating pellet and a resilient pad. The pad occupies the space between the under surface of the pellet and the lower shell and performs an insulating function, in addition to directing heat from the pellet in an upward direction rather than downwardly or laterally.
Each of the forgoing systems suffers from disadvantages. For example, systems which employ convection or conduction heating to preheat a food service container prior to employing the food service container to support, e.g., a dish having a food portion which is to be kept hot, require long “lead times” prior to being capable of being effectively used. Thus, such systems require relatively long periods of time in order to preheat the convection systems or other ovens used with said systems and in order to store enough heat in a heat sink or other heat storage means before the container can be usefully employed to keep foods warm in food service environments. Such lead times are undesirable and are typically on the order of about 60 to about 90 minutes and sometimes even longer, prior to the start of delivery or serving of the food to individual consumers.
Such food service containers including heat retentive servers and the like, suffer from other disadvantages. For example, heat retentive servers possess the disadvantage that the entire server can become hot and difficult to handle safely. Additional disadvantages include the fact that heat retentive servers which act as a heat sink, e.g., which employ a heat storage mass, tend to liberate heat in all directions. However, it is preferable to direct the heat which is liberated from the heat storage mass such that the heat is liberated substantially only within the heat retentive server itself, i.e., that portion of the heat retentive server which is enclosed by the bottom portion, side walls and dome or lid of the server. To achieve such an object, it is preferable to direct the heat given up by the heat storage mass such that the heat is directed upwardly.
U.S. Pat. No. 5,786,643 to Wyatt et al. is directed to a transportable heat retentive server, which includes a disk-shaped central portion having a disk-shaped heat storage disk. The '643 Wyatt et al. server design does not have heat retention times comparable to the present invention.
The present invention is distinguished from the above-described bases because the heat storage disk is embedded within a tray on which a plate sits. The present design requires minimal storage space, has less pieces to wash and dry, the system is lighter and further, there is no need for a base dolly. Surprisingly, the heat retention performance for the present tray system is improved by about 61% when compared with conventional heat retentive bases wherein the heat storage disk is stored in the base rather than the tray according to the present invention.
SUMMARY OF THE INVENTION
The present invention provides a heat retentive tray system including a tray that is adapted to be inductively heated and to also store heat via a heat sink disposed directly within the tray so as to keep hot foods hot. Further, the heat retentive tray system includes a dome portion, which is thermally disposed about a top surface of the tray such that it completely covers a housing for a heat sink, thereby providing additional heat retention.
The present invention also provides an inductively heated heat storage member which can be rapidly heated and ready for use in serving individual hot portions to individual consumers, in such fashion that a large number of such heat retentive trays can be “charged”, and plated with food in mass production fashion, while maintaining the food at least 140° F. for more than 60 minutes.
The present invention also provides a heat retentive serving tray or the like, which can be heated by induction heating to keep selected foods hot. The serving tray includes a metal portion (i.e., a heat storage disk) that is heated to a predetermined temperature in response to electrical or electromagnetic induction, e.g., by induction heating. The metal layer is preferably centrally located and embedded within a tray and preferably circular, but can be positioned in various locations and comprise other than a circular shape. Further, the location of the disk within the tray can be such that the disk is thermally isolated from the remainder of the structure of the tray, such that heat is not conducted to the remainder of the tray, such as, by using a thermal break or insulation. For example, a thermal break is preferably incorporated as pa
Aladdin Temp-Rite, LLC
Leung Philip H.
Womble Carlyle Sandridge & Rice PLLC
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