Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1999-11-23
2001-02-20
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S436000, C220S619000
Reexamination Certificate
active
06191393
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cooking utensil, and particularly, to a cooking utensil which preserves heat entrapped during cooking by having a double-layered wall structure and a method of fabricating such cooking utensil.
2. Discussion of the Related Art
Various types of cooking utensil are known and used in a kitchen. Such cooking utensil is made of one or more layers of stainless steel and has a single layer bottom. The single layer bottom is good for directly transmitting heat to the food contained in the utensil, but also causes burning of the food when carefully not attended to.
To solve the above problems, a cooking utensil having a double-layered structure has been proposed for preventing burnt food and to improve food flavor. One of such ideas is published in Korean Utility Laid-Open Publication No. 85-7307 which teaches that paraffin is injected between a space provided by a double-layered structure and an air-hole is established thereon. Instead of charging the space with paraffin, a structure into which a fluid of heat-medium is injected and sealed is disclosed in Korean Laid-Open Publication No. 97-4035. Moreover, a pot of a double-layered structure and a pot having a double-layered structure into which a working fluid is injected are taught by Japanese Laid-Open Publication No. 56-169825.
In such pots having the above-mentioned structures of the related arts, the gaps between the double-layered structure are filled with heat media to provide even-heat distribution and to save heat energy. Unfortunately, the structures of the related arts are first formed prior to injecting or filling the space formed betweeen walls with heat conductive substances. Thereafter, the outer wall is sealed or a valve is securely placed to prevent the heat conductive substances from leaking out. Such process increases manufacturing cost and decreases production yield.
The roaster of a double-layered structure, into which a heat conductive substance is injected according to the related art, generates high pressure due to internal expansion. To release the pressure safely, the roaster of the related art uses the method of installing a pressure control valve, establishing an inner shell of which shape is easily modified in accordance with the pressure, or reducing the pressure by forming a weak portion on an inner shell.
When the pressure control valve is embodied, the structure and the manufacturing process of the roaster become complicated as well as it is inconvenient to use the roaster due to the pressure control valve. Moreover, forming a weak inner shell reduces the life-span of the roaster. Also, the method of manufacturing a cooking utensil of a double-layered structure by depositing a space between the layers with a heat conduction medium and by sealing a deposit hole is troublesome and generates a leakage of the heat conduction medium due to the weak joint around the deposit hole. As a result, there is still no satisfactory method of sealing the heat conduction medium between the shells.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a roaster and a manufacturing method thereof that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.
The object of the present invention is to provide a roaster and a manufacturing method thereof which preserves heat efficiently as well as provides even heat distribution and provides a simple structure and easy to manufacture the same.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method of manufacturing a cooking utensil having outer and inner shells is described. The outer and inner shells form wall and bottom spaces between the outer and inner shells, wherein the the wall space is formed substantially along the height of the inner shell. The wall and bottom spaces contain at least partially a heat conductive medium. The cooking utensil also includes a heating coil arranged on the bottom of the outer shell for heating the outer shell of the cooking utensil.
The method of manufacturing comprises the steps of placing upright the outer shell on a concaved mold, the outer shell having a flange; placing a predetermined amount of the heat conductive medium into a space defined by the outer shell placed on the first mold; placing upright the inner shell in the outer shell so that the heat conductive medium at least partially surrounds the inner shell, the inner shell having a flange places substantially parallel to the flange of the outer shell; forming a rolled joint by curling the flanges of the outer and inner shells together a predetermined number of times to prevent the heat conductive medium from discharging from the space even when the cooking utensil is exposed to heat. The curling of the flanges of the outer and inner shells is carried out by placing at least one curling roller against the flanges while rotating the outer and inner shells with respect to the curling roller.
After the flanges of the outer and inner shells are curled for the predetermined number of times, the curling roller is pressed against at least one of the concaved and convexed molds to flatened the rolled joint. Preferably, there are two curling roller oppositely arranged to curl the flanges of the outer and inner shells.
In one aspect of the present invention, a convexed mold is placed in a space defined by the inner shell to firmly hold the inner shell with respect to the outer shell. There is also provided a controller connected to the heat coil to control amount and period of heat provided to the cooking utensil.
In another aspect of the present invention, the heat conduction medium is silicon oil. The silicon oil fills the space between the outer and inner shells about 65% by volume. Alternative to the silicon oil, the heat conduction medium may be ambient air.
Using the above described process, a cooking utensil is formed. The cooking utensil comprises an outer shell having an opening; an inner shell disposed inside the outer shell through the opening, forming wall and bottom spaces between the outer and inner shells, wherein the the wall space is formed substantially along the height of the inner shell, wherein the wall and bottom spaces contain at least partially a heat conductive medium; and a heating coil arranged on the bottom of the outer shell for heating the outer shell of the cooking utensil.
The cooking utensil includes a built-in controller arranged on outside of the outer shell and connected to the heat coil to control amount and period of heat provided to the cooking utensil. Moreover, a remote controller is provided which has a probe being coupled to the heat coil. The remote controller and the built-in controller are preferably electrically connected to exchange data signals with respect to each other.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
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Lee & Hong
Pelham Joseph
LandOfFree
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