Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2001-10-26
2002-07-09
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S412000, C219S494000, C219S413000
Reexamination Certificate
active
06417493
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the art of cooking appliances and, more particularly, to a method for cleaning a cooking appliance.
2. Discussion of the Prior Art
In the art of cooking appliances, it has been heretofore proposed to enable an appliance to operate in a self-cleaning mode. For example, in a conventional range having a cooking cavity which can be heated by one or more cooking elements arranged within the cooking cavity to perform at least baking and broiling functions, it is known to operate one or more of the cooking elements to perform a pyrolytic self-cleaning operation in order to cleanse the walls of the cavity from grease and other food soils developed during normal cooking operations. In such a cooking arrangement, the cooking elements used to perform the cleaning process are located entirely within the cooking cavity.
In addition, it is known to provide a catalytic self-cleaning oven. In such an arrangement, the walls of the oven are coated with a catalytic material which provides for self-cleaning of the oven cavity during cooking operations. In performing any self-cleaning function, byproducts, including smoke, gases and other odorous fumes, are inherently produced. A typical oven cavity will be vented to permit the escape of these byproducts to the ambient surroundings. In some cases, a catalytic oxidation unit is provided in the vent to react with the flowing byproducts.
In still other self-cleaning arrangements, a combination of pyrolytic and catalytic cleaning is performed. Regardless of the fact that various self-cleaning systems have been proposed in the art, there still exists a need for an improved self-cleaning system for a cooking appliance which maximizes the elimination of byproducts, while also minimizing the necessary operating time for the self-cleaning mode. Particular concerns are raised in connection with the necessary operating time and byproduct elimination in a self-cleaning convection oven which essentially relies on a heated flow of recirculating air for raising the temperature in an oven cavity. In any event, there exists a particular need for an improved self-cleaning system for a convection cooking appliance, as well as an improved cleaning method for such a cooking appliance.
SUMMARY OF THE INVENTION
The present invention is directed to a system for self-cleaning an oven cavity of a convection cooking appliance, particularly an appliance including an air channel assembly which is defined by ducting extending about portions of the oven cavity for directing a recirculating flow of air into and out of the oven cavity. The overall system utilizes various heating elements, as well as a catalyst, to enhance the pre-heating of the oven cavity, efficiently eliminate developed smoke, odor and other byproducts, and effectively reduce the necessary cleaning cycle time for the appliance.
In accordance with a preferred embodiment of the invention, the convection cooking appliance includes first, second and third heating units which are individually controlled, along with a blower unit, in performing a self-cleaning function for the appliance. The first and third heating units are disposed in the air channel assembly, while the second heating unit is positioned in the oven cavity. A controller is provided for regulating the activation and deactivation state of the various components in a manner which preheats the oven cavity in a relatively short time period, while assuring that initially developed smoke, gases and other odorous fumes inherently produced as byproducts of a self-cleaning operation are effectively eliminated.
During the preheat phase of the cleaning mode, the controller initially activates the blower element in combination with each of the first and third heating units in the air channel assembly, with the developed flow of air through the oven cavity being directed to the catalyst for elimination of the byproducts. Following the preheat phase, at least the blower and the third heating element are deactivated and the second heating unit is activated to rapidly heat the oven cavity through a radiant heating operation. A temperature sensor is linked to the controller to efficiently determine the optimum time to switch between the various heating sources for the oven cavity during the overall self-cleaning operation.
In accordance with a preferred self-cleaning method according to the invention, an initial, catalyst pre-heat stage, established mainly for smoke elimination purposes, is followed by a moderately high-temperature presoak stage to bum off various light molecular weight hydrocarbons and the like. For the main cleaning operation, a high temperature stage is initiated in combination with a high convection air flow to establish high oven surface temperatures in a minimal time frame. This timed stage is followed by a cool down period wherein both the temperature and the convection speed are reduced. Thereafter, providing an intermediate temperature heating stage with medium convective air flow, followed by a cooling stage, is provided for preset time periods. This combination of intermediate temperature heating and subsequent cooling stages is repeated until the total self-cleaning time is completed.
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Bales Michael E.
Brown John Scott
Whipple, Jr. Robert Z.
Diederiks & Whitelaw PLC
Maytag Corporation
Pelham Joseph
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