Stoves and furnaces – Stoves – Cooking
Reexamination Certificate
1999-05-21
2001-05-08
Yeung, James C. (Department: 3743)
Stoves and furnaces
Stoves
Cooking
C126S01500R, C219S400000, C034S216000
Reexamination Certificate
active
06227189
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to high heat transfer rate convection ovens utilizing heated jets of air to cook food product, and more particularly an air delivery duct system for a convection oven or cooling apparatus.
BACKGROUND OF THE INVENTION
The present invention relates to a high velocity convection oven capable of cooking foods that are traditionally cooked by deep fat frying methods, without producing undesired smoke and smoke flavor in the food. More specifically, the oven of the present invention produces high velocity jets of air to cook food product while the food product is moved relative to the air jets, with the preferred method of moving food product being a conveyor assembly. High velocity convection ovens of this type are generally referred to as impingement ovens.
In sum, the oven is characterized by its production of very high transfer rates needed for cooking traditionally deep fat fried foods with air. While conventional impingement type ovens (e.g., see U.S. Pat. No. 4,338,911) have been known to produce heat transfer rates in the range of 12-15 (as measured by a heat transfer rate measurement device of the type described in U.S. Pat. No. 5,161,889), the oven of the present invention is capable of producing heat transfer rates of up to 25 and greater. At the same time, the present oven design also has features which control the amount of smoke produced in the cooking cavity, thereby reducing or eliminating the off-flavor that could be caused by the smoke.
Further, the oven includes dual cavities surrounding the cooking chamber through which room temperature air is circulated. This “cool skin” feature cools the interior walls of the cooking chamber to promote grease collection and retard smoke production. This feature also cools the exterior walls of the oven making the oven safer for use. In addition, the oven of the present invention features an improved air delivery (duct) design that produces more even distribution of temperature controlled cooking gasses to the food product and self-cleaning capabilities using pyrolytic cleaning methods.
SUMMARY OF THE INVENTION
The present invention relates to a gas delivery assembly for a heating or cooling apparatus. The system includes a blower and a duct in fluid communication with the blower (and preferably a plenum in communication with the blower and duct). The duct has a proximal end and a distal end with an inlet opening adjacent the proximal end through which temperature controlled gas enters. The duct further includes a plate extending along its length with a plurality of orifices through which the gas exits the duct. Improved evenness of distribution of gas through the orifices is achieved by the ducts design which includes a first tapered portion adjacent the proximal end and a second tapered portion adjacent the distal end, the first tapered portion having a greater angle of taper than the second tapered portion.
In a preferred embodiment, the duct is designed such that the first tapered portion extends about ¼-½ of the length of the duct.
In another preferred configuration of the duct, the first tapered portion tapers about 1 inch per 7 to 16 inches of length of the duct and the second tapered portion tapers about 1 inch per 1.5 to 3 inches of length of the duct.
In another aspect of the invention, the orifices in the duct plate comprise nozzles, preferably circular in shape and extending ⅛ inch from the plate.
REFERENCES:
patent: 4462383 (1984-07-01), Henke et al.
patent: 4591333 (1986-05-01), Henke
patent: 4960100 (1990-10-01), Pellicane
patent: 4965435 (1990-10-01), Smith et al.
patent: 5254823 (1993-10-01), McKee et al.
patent: 5423248 (1995-06-01), Smith et al.
patent: 6131559 (2000-10-01), Norris et al.
patent: 2709068 (1978-07-01), None
Cocks Josiah C.
Patentsmith Technology, Ltd.
Sidley & Austin
Yeung James C.
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