Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1998-02-18
2001-10-30
Jeffery, John A. (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S411000, C219S438000, C099S339000, C392S416000
Reexamination Certificate
active
06310325
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a multiple function steamer and cooker oven which can cook with atmospheric steam or steam under pressure, without a separate steam generator; cook with supplemental radiant heating to enhance cooking capabilities, superheated steam, or cook without steam. As an improved feature a vacuum can be drawn within the cooking chamber to provide vacuum marination of food and subatmospheric pressure steam cooking in combination with the above cooking processes.
DESCRIPTION OF THE PRIOR ART
Combination steamer and convection ovens are well known and have been in use both commercially and to some extent domestically for many years. In addition, as is well known to those skilled in the art, cookers are available which utilize steam under pressure, or atmospheric steam. In these commercial cookers the steam is often generated in a separate steam generator and piped into the cooking vessel. While domestic and commercial pressure cookers have been in use for several years, generation of steam within the cooking chamber under pressure or at atmospheric pressure, on a commercial scale, is not available.
In cooking with steam, steam condenses on the cooler food product releasing the eat of condensation to cook the food. In conventional units the steam also condenses on he walls of the cooker and on the cooler cooking pan so that the cooking procedure is relatively inefficient. Heat of condensation then is lost to condensation on non-food structural portions of the conventional steamer oven.
It is also known that steam cooking will not caramelize or brown the outer surface of the food being cooked, and therefore in certain products it is necessary to supplement the steam with a resistance heater.
For example, in U.S. Pat. No. 4,839,502, there is described a cooker which uses steam, but also includes a black body used to emit what is described as long wave length radiation and to absorb short wave length radiation. The black body is said to initially absorb both short wave and long wave length radiation and reradiate only the long range wave length radiation to cook the foodstuff. This is described as necessary to take advantage of the penetrating ability of long wave length radiation. The patent required the use of long wave length over short wave length for cooking purposes.
In that patent there also is a teaching for stopping steam generation when the internal temperature of the foodstuff reaches a desired level and using external air to remove moisture by evaporation from the foodstuff. Further cooking is then achieved without steam to brown the product with what is described as long wave radiation which allows moisture within the foodstuff to move to the surface and evaporate.
However, contrary to the teachings of this patent short range radiation (0.76-2 um) has greater penetrating ability than medium (2-4 um) and medium range radiation has greater penetration than for long range (4-10 um ) radiation. Water in food is most susceptible to radiation at 3 um and at 6 um where 100% absorption is exhibited. The burning or browning of meat and other foods is due to short range radiation.
In terms of temperature, at 212 degrees Fahrenheit surface temperature, the I.R. peak wave length is 7.8 um with a total radiated energy from a black anodized aluminum surface of 887 Watts/sq, meter. At 350 degrees Fahrenheit surface temperature the wave length is 6.4 um with a total radiated energy of 1896 Watts/sq. meter.
The engineering data available then does not support a preference for long wave radiation for cooking purposes.
In U.S. Pat. No. 4,495,932, there is described a steamer which uses super heated steam. The device uses a first chamber to generate the steam and a second chamber to super heat the steam. The steam then flows from the chamber onto the food. The patent however does not describe a radiant heating function for the product.
Other steaming devices are described for example in U.S. Pat. Nos. 5,363,748; 4,810,856; 4,655,192; 4,430,557; 5,411,753; 5,235,903; and 5,318,792.
In U.S. Pat. No. 5,507,332, there is described an apparatus for marinating meat using a vacuum induced within the unit to facilitate the marinating process. This patent however does not describe a cooking function but is limited to the description of a pressure vessel used to vacuum marinate at room temperature.
SUMMARY OF THE INVENTION
It has been discovered however that a superior cooking device can be provided that combines the functions of marinating, steam cooking, and radiant cooking, alone, in combination, at atmospheric pressure, reduced pressure, or at an elevated pressure.
According to the device of this invention the steam chamber is manufactured from a highly conductive metal such as cast aluminum wherein the sides, base and upper portion are all cast with circumferential ribs extending outwardly from the outer surface to facilitate the structural integrity of the device. The steam chamber may have a separate decorative outer enclosure as will be subsequently described.
Steam then is generated in the base of the chamber, preferably by resistance heaters embedded in the base and ceiling of the unit or attached to the structure external to the chamber so that the interior of the chamber is heated externally by heating the surrounding walls, ceiling and base by conduction. In this manner the walls of the structure are typically maintained at a temperature higher than the cooking temperature of the food product.
By heating the walls, steam generated will condense on the food product and food containers rather than on the walls of the structure to maximize the heat of condensation delivered to the food product.
By providing heaters in a dome-shaped ceiling, the ceiling itself generates both long and mid-range length wave radiation within the structure. The long wave radiation is used, as is well known, to cook the food product either in combination with steam, or after steam has raised the internal temperature of the food product to a predetermined level. In addition, mid-range wave length radiation generated by the dome ceiling can be used to superheat steam. The domed or multi-angled ceiling then has multiple functions. The dome shape focuses radiant heat waves and reflects heat onto the food located in one or more pans in the chamber. The dome also forces condensation to roll down the sloping ceiling and the walls, back into a reservoir in the base to help eliminate condensation from the ceiling dripping downwardly onto the food. The problem of condensation dripping onto the food is typical of steamers in the prior art. By minimizing condensation on the food dripping from the ceiling, heat transfer to the food is facilitated.
The steam within the chamber also tends to roll and billow downward from the domed ceiling causing re-circulation of heated air and more efficient cooking. While the heated dome ceiling can function to super heat the steam, steam will also be super heated in any event as it collects in the ceiling from generation in the base of the unit. Steam generated in the base then travels upwardly through and around the food product to be cooked and upon encountering the dome tends to billow downwardly to re-circulate until it condenses. If desired, after steaming the heated ceiling can be used to generate long wave radiation to brown the food product and thereby assist in cooking it. As will be obvious to those skilled in the art, if desired, the heated ceiling and/or sidewalls can be used with steam, or the heated ceiling and walls can be used as a sole source of heat for cooking.
Because the device of this invention is a pressure vessel, it is possible, in one embodiment, to incorporate a vacuum pump to draw down the pressure within the vessel. Food can then be marinated by soaking it or coating it with the appropriate marinade, then pressure conditions are reduced so that when pressure is restored the sauce will be rapidly absorbed by the food product. The unit of this invention is susceptible, in this embodiment, to automatic operation whereby meat
Casdy, Esq. Donald C.
Colburn Treat, LLC.
Jeffery John A.
LandOfFree
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