Electric heating – Heating devices – With power supply and voltage or current regulation or...
Reexamination Certificate
1999-03-19
2001-05-22
Paschall, Mark (Department: 3742)
Electric heating
Heating devices
With power supply and voltage or current regulation or...
C219S483000, C219S501000, C219S506000, C073S587000, C099S325000
Reexamination Certificate
active
06236025
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a system for determining boil states of the contents of cooking utensils while being heated, and to a method for determining boil states. More specifically, the invention relates to an acoustic sensor system for use in determining boil states, and an associated method for determining boil states using an acoustic sensor system.
Boiling water or other fluids or foods (generically “liquids”) is a common step in cooking; for instance it is one of the most common uses for a range. It is typically desirable to closely monitor the boil phase of the liquid during such processes, i.e., to identify the pre-simmer, simmer onset, simmer and/or boil phases. In this regard, the pre-simmer phase is generally characterized by a calm liquid and the simmer onset phase is the initial, slow bubbling of the liquid characterized by the appearance of individual bubbles. During the simmer phase, bubbles appear in jets creating the effect commonly referred to as simmering. Finally, in the boil phase, the bubbling of the liquid is generalized, resulting in the familiar turbulence of a boiling liquid. These phases can be identified by experts and experienced cooks. The formation and collapse of the bubbles during the phases create an acoustic signature which changes with the size and number of the bubbles, the rate of their formation, their collapse, and the temperature gradient in the liquid. This acoustic response includes the audible component, which can be easily observed when cooking, as well as responses in various frequency bands. It is also affected by factors including the type of cooking vessel and any ingredients in the liquid.
The boil phase is monitored for a number of reasons. First, many cooking processes require that the liquid be attended to upon identification of a particular boil phase, e.g., reducing the heat after the liquid reaches a boil. In addition, the boil phase may be monitored to reduce heat upon boiling so as to prevent boil-over which can result in a burned-on mess or, in the case of gas ranges, extermination of the cooking flame. In addition, the boil phase may be monitored to reduce heat after the liquid reaches a boil, either to reduce it to a simmer for cooking purposes or to prevent boil-over. Boil-over can result in a burned on mess or, in the case of gas ranges, extermination of the cooking flame. Moreover, a liquid not monitored when boiling can boil dry, resulting in burning of the food, damaging the cooking utensil, as well as presenting potential fire hazards.
Generally, the boil phase is monitored visually. Such visual monitoring can interfere with the user's ability to prepare other foods or be otherwise disposed during heating of the liquid. Moreover, a busy or inexperienced cook may fail to accurately, or in a timely manner, identify a boil phase of interest.
Increasingly, manufacturers seek to provide, and consumers desire to have, appliances with a greater degree of automated operation and control. With the increasing affordability of integrating computing power into an appliance, there exists a potential to provide the increased levels of automated control. However, information gathering tools or devices that interact with a computer or microcontroller in monitoring or controlling the operation of the appliance must also have desirable cost and performance attributes.
For cooking appliances generally, and for electric and gas range cooktops specifically, automation or partial automation of control of the cooking process, or monitoring of cooking on a cooktop, has traditionally focused on temperature monitoring or sensing. Various temperature sensors have been proposed for sensing the temperature of a surface heating unit or a cooking utensil positioned thereon or food contents therein, and for controlling the heat input to the heating unit, based upon the sensed temperature. Such sensors have commonly been proposed for use in connection with glass-ceramic radiant cooktops, and purport to enable detection and control of cooking states. The sensors essentially measure temperatures directly, and are frequently coupled to the heating unit control system to provide feedback to the control system.
Temperature-based sensing systems for range cooktops may indirectly or inferentially provide information regarding a boil state of a liquid contained in a utensil and being heated on the cooktop. However it continues to be a problem in cook-top sensing and control to provide a method for reliably determining the boil state since the correlation between temperature and boil state depends on a number of variables including, but not limited to, type of liquid, the amount of liquid, any additives, the position of the utensil, and the utensil's warpage. For instance, it is well known that the addition of salt into water raises the boiling temperature. Environmental conditions such as elevation can also affect the temperature associated with boil states. Finally, the position of the temperature sensor and its calibration can also have a significant impact on achievable accuracy. The general need then is to develop an approach to boil state determination that is more robust to cooking modalities, vessels used, various user interactions, and other variations, or disturbances, in the equipment or environment.
BRIEF SUMMARY OF THE INVENTION
In an exemplary embodiment of the invention, a cooking range is provided with an acoustic sensing system for determining the boil state of the contents of a cooking utensil positioned on a cooking surface or otherwise being heated by a cooking appliance. The acoustic sensing system, which includes at least one acoustic sensor, is positioned on the cooking range to detect acoustic emissions in one or more specific ranges of frequencies that are characteristic of emissions resulting from the heating and boiling of water, or other liquids, in a variety of cooking utensils.
It has been determined in the development of the present invention that the various phases of boiling have distinctive acoustic signatures, and that the acoustic signatures are repeatable. Further, it has been determined that the acoustic signatures are obtained, even when cooking conditions, such as varying liquid levels, or load sizes, are changed in the presence of common disturbances, such as stirring.
Several different types of low cost acoustic sensors are suitable for incorporation into cooking ranges. By sensing the acoustic signature of a cooking utensil containing liquid, a signal can be transmitted to a cooktop controller which generates an indication signal of the boil state of the liquid in the utensil.
An exemplary embodiment of the method of the invention includes sensing an acoustic signature of a utensil containing a liquid positioned over a heating source or an induction heating coil of a cooktop, relaying a signal corresponding to the acoustical signature to a cooktop control system, and adjusting, as necessary and as determined by the cooktop control system, the heating source, the induction heating coil, or to provide feedback to the user.
The system and method thus provide a low-cost way of determining the boil states, including, but not limited to, simmer onset, boil, boil over and boil dry states, for the contents of a cooking utensil on a range cooktop. This is achieved by taking advantage of the consistent, repeatable and distinctive acoustic signatures of liquid in various cooking utensils at various boil states, sensing those signatures with one or more acoustic sensors, and processing the acoustic sensor data to efficiently control the cooking process.
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Badami Vivek Venugopal
Berkcan Ertugrul
Saulnier Emilie Thorbjorg
Song Limin
Breedlove Jill M.
General Electric Company
Paschall Mark
Thompson John F.
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