Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2003-01-27
2004-09-07
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S400000, C219S413000, C219S492000, C219S497000
Reexamination Certificate
active
06787738
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates generally to cooking ovens, and, more particularly, to control systems for self-cleaning ovens.
Cooking ovens include a cooking cavity having a number of interior walls and an access door, and one or more heating elements cook food placed into the cooking cavity. As the oven is used, the interior walls and interior portions of the cooking cavity and the door are inevitably soiled with cooking residue. Cleaning the oven of this unsightly residue can be a difficult endeavor.
Some types of ovens are operable in a self-cleaning mode wherein the oven heating elements are operated to raise the oven temperature to levels sufficient to burn soil off of the internal surfaces of the oven. Once this temperature is reached, the oven temperature is maintained for some time to satisfactorily remove the residue from the interior of the oven. The cleaning process produces a considerable amount of by-products which are exhausted from the oven cavity through a vent. See, for example, U.S. Pat. No. 4,481,404.
Typically, the self-cleaning cycle is a time-based operation that lasts up to four hours at high oven temperatures, for example, of about 900° F. Energy consumption in the self-clean cycle can therefore be substantial. In electronically controlled ovens, the oven controllers include programmed pre-determined default times for a self-clean algorithm execution. Under average use conditions, the default time is adequate to clean the oven. This approach, however, is disadvantageous in several aspects as oven soil conditions vary in use, because the self-clean cycle is executed for the duration of the default time and generally without regard to a condition of the oven.
Thus, for example, when the oven cavity is relatively clean, the default clean time tends to be excessive. That is, the self-clean cycle continues for some time after the oven is actually cleaned. Excessive self-clean cycles are inefficient from both a time and energy perspective.
In contrast, when the oven cavity is heavily soiled, the default clean time may not be long enough for the oven to be adequately cleaned. Insufficient clean times lead to unfulfilled consumer expectations and decreased customer satisfaction with the oven.
SUMMARY OF INVENTION
In one aspect, a self-cleaning oven is provided. The oven comprises an oven cavity, a gas sensor in flow communication with the oven cavity and a controller configured to select one of a plurality of self-clean cycle times based upon a peak value of an output signal from said gas sensor in a self-clean cycle.
In another aspect, a self-cleaning oven is provided. The oven comprises an oven cavity, an exhaust vent in flow communication with said cavity, a gas sensor in flow communication with said exhaust vent, and a controller configured to select one of a plurality of predetermined self-clean cycle times based upon a peak value of an output signal of said gas sensor.
In another aspect of the invention, a self-cleaning oven is provided. The oven comprises an oven cavity, an exhaust vent in flow communication with said cavity, a gas sensor in flow communication with said exhaust vent, a cooling fan, and a controller. The controller is configured to cycle said fan on and off for a predetermined number of times in a self-clean cycle, and, when said fan is off, to read a sensor output from said gas sensor. Once a predetermined number of sensor readings have been obtained, the controller is configured to identify a peak value of said readings, and, based upon said identified peak value of said readings, to select one of a plurality of predetermined self-clean cycle times based upon said identified peak value.
In another aspect, a method of controlling an oven in a self-clean cycle is provided. The oven includes an oven cavity and a gas sensor in flow communication with the oven cavity, and a controller receiving an output signal from said gas sensor and operatively coupled to an oven heating element to raise a temperature of the oven cavity. The method comprises initiating a self-clean cycle when activated by a user, operating the oven heating element to heat the oven cavity, sensing a level of gas in said oven cavity at predetermined intervals over a predetermined time period, and, based on said sensed gas levels, identifying one of a plurality of soil levels in the oven cavity and selecting a self-clean time value in response to the sensed gas levels.
In still another aspect, a method of controlling an oven in a self-clean cycle is provided. The oven includes an oven cavity and a gas sensor in flow communication with the oven cavity in an exhaust vent, a controller receiving an output signal from the gas sensor and operatively coupled to an oven heating element to raise a temperature of the oven cavity, and a cooling fan in flow communication with the controller. The method comprises initiating a self-clean cycle when activated by a user, operating the oven heating element to heat the oven cavity, establishing a reference signal from the gas sensor in a first stage of the self-clean cycle, cycling the fan on and off in a second stage of the self-clean cycle, sensing a level of gas in said exhaust vent in an off portion of each cycling of the fan to obtain a predetermined number of sensor readings, identifying a peak value of the sensor readings in the second cycle, subtracting the reference signal from the peak value to determine an absolute sensor reading, and based upon the absolute value of the sensor reading, selecting one a plurality of predetermined self-clean times.
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Cissell Robert
Haidar Omar
Horning Scott
McGonagle Michael
Odorcic Kresimir
Armstrong Teasdale LLP
General Electric Company
Houser, Esq. H. Neil
Pelham Joseph
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