Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-06-05
2001-05-29
Paik, Sang (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S518000
Reexamination Certificate
active
06239414
ABSTRACT:
TECHNICAL FIELD
The present invention relates to controls for stoves in general. More specifically to an automatic control mechanism that turns off the stove when liquid has boiled to the desired level.
BACKGROUND ART
Previously, many types of devices have been developed in endeavoring to provide an effective means for controlling the amount of evaporation of a liquid on a stove or other heating apparatus. In most cases the liquid is housed in a given volume container and a spring is used that is non adjustable or the adjustment must be made by experimentation. Others use pressure switches which are responsive to a predetermined weight of the container or boils the liquid into another container reducing the weight and opening an electric circuit to turn off the heat source.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however the following U.S. patents are considered related:
Patent Number
Inventor
Issue Date
4,334,955
Zoeke et al.
Jun. 15, 1982
4,164,644
Remsnyder et al.
Aug. 13, 1979
2,070,491
Park
Feb. 9, 1937
2,020,364
Lehmann
Nov. 12, 1935
Foreign Patents
FR2467-577
Santini
Oct. 23, 1979
(France)
Zoeke et al. in U.S. pat. No. 4,334,955 teaches a device for controlling evaporation of liquid using a container on a base plate supported by a leaf spring. The spring loaded plate allows the plate to move between two micro switches depending upon the amount of liquid in the container. The switches are connected to a control circuit for activating the heating element and interrupt the flow of power to the heating element when little or no liquid is present in the container.
U.S. Pat. No. 4,164,644 issued to Remsnyder et al is for a heating unit which heats the contents of a container. An electrical circuit is responsive to a pressure switch that reacts to a predetermined weight of material in the container. A pivotally mounted heating element activates a switch which interrupts the circuit in the event of overheating. The heating unit is provided with a heating element having a conical center portion surrounded by an annular flat or planar surface for receiving a container having only a predetermined shaped bottom for accommodating the particular shape heating element.
Park in U.S. pat. No. 2,070,491 discloses a heating system that passes a circuit of high amperage and low voltage power directly thorough a pan. The pan has downwardly projecting prong like contacts which firmly engage the pan to an electric power supply. The high amperage and low voltage may utilize the secondary circuit of a transformer from 110 volt lighting mains. When the heating is completed, a switch energizes a solenoid and power flows thorough to a motor magnet providing the released of the clamps.
Lehmann in U.S. pat. No. 2,020,364 teaches means for adjusting a device for receptacles or containers differing in weight to provide a varying minimum in weight of content to render the heating device ineffective. A tension spring reacts on a lever to separate electrical contacts when the weight of the container and its contents reach a predetermined minimum. The combined minimum weight can be experimentally determined by the adjustment of the spring element when the liquid in the container is just, or slightly more that sufficient to protect the container from overheating. No attention is required to protect the device from overheating since it will automatically shut off when the minimum amount of liquid in the container is reached.
Santini in French patent FR2467-577 discloses a milk bottling appliance using two vessels one taller than the other with a spout on the taller of the two overhanging the smaller vessel. The taller vessel is placed on a heating plate which has a vertical rod passing therethrough which acts as a counterweight holding the plate horizontal against a stop on the rod. When the vessel is filled the weight of the fluid overcomes the counter weight and the lever falls closing a spring contact which closes an electric circuit to the heating element. Once the liquid has boiled over into the smaller vessel the reduced weigh to the heating vessel allows the lever to rise and the spring contacts to opens the electric circuit.
DISCLOSURE OF THE INVENTION
In the past stoves for cooking rely on the user to manually control the cooking time on stove top heating. Help is sometimes used such as built in timers that indicate the lapsed time using a buzzer to warn the user that the preset time has lapsed and the cooking period is finished. While this type of warning is usually sufficient for warming foods or when the cooking time is actually known, if the heat is continued beyond this point disastrous results may occur. This problem is obvious when boiling a liquid for a time period when it is not a certainty as to the actual time it takes to accomplish the end result. In this case a timer is of little use and it is therefore expedient that the user pays strict attention to the process. It is therefore a primary object of the invention to have a system that is easy to operate and simple to control using automatic features that rely on the weight of the liquid to be boiled by presetting the system originally and then adding a small additional amount to the container, to allow for evaporation, with the stove then automatically shutting down when the original level is achieved.
An important object of the invention is the protection that is afforded by preventing the food to be ruined by overcooking or even by burning the food when the moisture content has been lowered to a point where the heat actually begins to alter the structure of the food itself.
Another object of the invention is the freedom that is afforded to the user as once the stove has been adjusted and the automatic control pre-set no further attention is required as the stove will shut itself off at the exact time.
Still another object of the invention is to eliminate the possibility of odor of burned food on the stove top that may permeate the entire kitchen and sometimes even the entire house that could have lasting effects.
Yet another object of the invention is the prevention of liquid in the container actually burning to the extent that other materials near the stove may catch on fire which may lead to catastrophic results.
A further object of the invention averts the possibility of the container to boil dry actually melting the metal and destroying the surrounding area, this anomaly is particularly apparent with aluminum containers.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 2020364 (1935-11-01), Lehmann
patent: 2070491 (1937-02-01), Park
patent: 2520788 (1950-08-01), Wales
patent: 2715176 (1955-08-01), Schoberle
patent: 3586824 (1971-06-01), Barney
patent: 4164644 (1979-08-01), Remsnyder et al.
patent: 4334955 (1982-06-01), Zoeke et al.
patent: 5823095 (1998-10-01), Walker
patent: 2467-577 (1979-10-01), None
Anderson Gordon K.
Paik Sang
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