Electric heating – Inductive heating – With heat exchange
Reexamination Certificate
2001-08-17
2003-10-07
Van, Quang T. (Department: 3742)
Electric heating
Inductive heating
With heat exchange
C219S665000
Reexamination Certificate
active
06630650
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to induction cooking. The present invention relates more particularly to an induction heating and control system and method having enhanced reliability and having advanced performance features, for induction cooking devices such as induction heating ranges. As discussed in detail below, the present invention comprises an induction heating system which integrates voltage management, power management, thermal management, digital control sensing and regulation systems, and protection systems management.
BACKGROUND OF THE INVENTION
Induction heating for use in cooking is well known. Induction ranges in particular have been designed and built by many different companies. The basic circuitry and coil design for contemporary induction ranges have concentrated on the basic electronics for making induction heating work in a fundamental way. The reliability, the performance and the user friendliness of induction ranges have been limited on contemporary ranges. Contemporary induction ranges have been particularly limited to residential use and have exhibited severe drawbacks which limit their desirability for commercial use. Moreover, the inability to provide high reliability for residential and commercial kitchen induction ranges, the inability to cook at high temperatures and various other performance drawbacks have substantially limited the usefulness of contemporary induction ranges.
For example, most contemporary induction ranges suffer from the deficiency of requiring that each range must specifically be configured so as to accommodate a single input voltage, typically such as either 208 volts or 240 volts. When subjected to a wide voltage range the result is poor voltage regulation of the 50/60 HZ auxiliary housekeeping suppliers used in typical induction ranges.
Further, contemporary induction ranges provide very coarse control of the heating provided thereby. This makes it very difficult to properly cook many food items which require precise control of the heat applied thereto during cooking.
Further, contemporary induction ranges merely react to the heat control knob and provide a given amount of power in response to the setting thereof. Therefore, different cooking results will occur due to the use of cooking utensils or containers having different magnetic properties. That is, turning the heat control knob of a contemporary induction range to a given setting e.g., the midpoint thereof, will not necessarily result in the same heating effect when different pans (typically having different iron content and thus having different magnetic properties) are utilized. Of course, this results in undesirably different and unpredictable cooking of food items when different utensils or containers are utilized.
Indeed, some cooking utensils or containers are known as “killer pans” because of their ability to over-drive an induction cooker in a manner which results in damage to the induction cooker.
Contemporary induction ranges limit the amount of power which may be applied to item being cooked. This results in undesirably lengthened cooking times. It may even result in the inability to prepare some food items which require a higher level of heat, at least during some portion of the cooking process.
One problem commonly associated with contemporary induction ranges is the leakage of spilled liquid from the cook top to internal electrical circuitry thereof in the event that the cook top become cracked or broken. Typically, such leakage results in substantial damage to the electrical components of the induction range.
Another problem with contemporary induction ranges is that there is no accurate visual indication of the amount of power being utilized in the cooking process. That is, it is not possible to merely look at the induction range and determine the degree to which a food item is being heated.
In view of the foregoing, it is desirable to provide an improved induction heating and control system and method which addresses and mitigates the problems associated with contemporary induction ranges and the like.
SUMMARY OF THE INVENTION
The present invention specifically addresses and alleviates the above-mentioned deficiencies associated with the prior art. More particularly, one aspect of the present invention comprises a method for sensing AC line voltage for an induction cooker, wherein the method comprises sensing a voltage across a secondary winding of a flyback transformer.
According to another aspect, the present invention comprises a method for generating a high resolution, variable frequency waveform, wherein the method comprises providing an oscillator which is configured such that a frequency of an output thereof depends upon a resistance value. A resistor network is digitally switched so as to vary a resistance provided thereby to the oscillator in a manner which varies the frequency of the output of the oscillator.
According to yet another aspect, the present invention comprises a method for cooking with an induction cooker, wherein the method comprises inductively applying power to a ferrous cooking container, sensing the electrical characteristics of the load (ferrous cooking container), the induction coil current of the applied power, and adjusting the power applied based upon the sensed load such that a desired amount of power is applied to the cooking container for maximum performance and protection.
According to yet another aspect, the present invention comprises a method for cooking with an induction cooker, wherein the method comprises sensing a temperature of at least one location proximate the ceramic glass top, and regulating power of the induction cooker so as to maintain a desired value for each sensed temperature for maximum performance and protection.
According to yet another aspect, the present invention comprises a temperature resistant, substantially rigid material for supporting a cooking container during induction cooking, and a temperature resistant, substantially flexible material disposed proximate the rigid material. The flexible material is configured so as to inhibit spilled liquids from undesirably contacting electrical circuitry of the induction cooker in the event that the rigid material cracks, breaks, or otherwise allows such spilled liquids to pass therethrough.
According to yet another aspect, the present invention comprises a light disposed proximate an induction coil, such as being disposed beneath the ceramic or glass cook top, wherein the light illuminates with varying intensity so as to indicate the power being provided to the cooking utensil or container.
These, as well as other advantages of the present invention, will be more apparent from the following description and drawings. It is understood that changes in the specific structure shown and described may be made within the scope of the claims without departing from the spirit of the invention.
REFERENCES:
patent: 4358654 (1982-11-01), Estes
patent: 5968398 (1999-10-01), Schmitt et al.
patent: 6153863 (2000-11-01), Snowball
Bassill Nicholas
Jamerson Clifford
Wang Dongyu
Carte Norman E.
Luxine, Inc.
Van Quang T.
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