Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-08-29
2001-05-01
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C126S02100R
Reexamination Certificate
active
06225604
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 drive and support structure for a blower used in a self-cleaning convection oven.
2. Discussion of the Prior Art
Tremendous advancements have been made in the art of cooking appliances in the relatively recent past. For instance, it was not many years ago that conduction and/or radiant heat sources were almost exclusively relied upon in connection with household ranges and wall ovens. However, more recent trends are to further take advantage of convection as an additional heating system. That is, a flow of air can be circulated through an oven cavity, while being subjected to one or more heat sources, with the heated air being distributed into the oven cavity to develop substantially uniform cooking of a food product.
As with more conventional oven cooking arrangements, it is desirable to provide a self-cleaning function for the oven cavity regardless of the particular type of heating source(s) used with the convection oven. However, with such an arrangement, the air handling system can be subjected to extreme temperatures. Various components of the air handling system, such as a bearing arrangement utilized to rotatably support a blower element of the system, can be adversely affected when subjected to such high temperatures.
Based on the above, there exists a need in the art for a blower assembly used in a cooking appliance, including an oven cavity adapted to operate in at least cleaning and convection cooking modes, wherein sensitive components of the blower assembly are isolated from extreme temperatures during operation of the cooking appliance. In addition, there is a need for a blower assembly for a convection cooking appliance which is easy to assemble, reliable and cost effective, while being designed to establish a temperature gradient between its various components which assures that more temperature sensitive components are protected.
SUMMARY OF THE INVENTION
The present invention is directed to the drive and support structure for a high speed blower assembly used in a self-cleaning, convection oven. In such an environment, a blower element of the assembly can be subjected to extreme temperatures, including those reaching and exceeding 900° F. (approx. 480° C.). In accordance with the invention, the blower element is secured to the first end of a tubular section of a drive shaft which, in turn, is rotatably supported by one or more bearing units. In the most preferred form of the invention, an opposing end of the tube has secured thereto a sheeve used for rotating the blower element and drive shaft through a motor and pulley arrangement.
In accordance with the invention, it is desired to reduce the conduction of heat from the blower element, through the tube and into at least the bearings. For this purpose, the tube has fitted therein a rod which is formed of a material having a relatively high thermal conductivity as compared to the tube. In the most preferred embodiment of the invention, the tube is formed of stainless steel and an aluminum rod is pressed-fit into the tube. Most preferably, the rod extends from the second end portion of the tube, concentrically past the bearings, but terminates short of the blower element such that a thermal air break zone is defined, within the tube, between the aluminum rod and the blower element.
With this arrangement, given the relatively low coefficient of thermal conductivity of the tube, as well as its reduced cross section, the temperature gradient between the blower element and the tube is increased. The aluminum rod acts as a heat sink which functions to further reduce the temperature to which the bearings are subjected. Therefore, due to the gradient created and the function of the heat sink, the operational temperatures experienced by the shaft bearings are substantially reduced.
Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment thereof when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several view.
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Diederiks & Whitelaw PLC
Fastovsky Leonid
Maytag Corporation
Walberg Teresa
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