Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-06-14
2001-09-04
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S628000, C219S393000, C250S574000, C356S438000, C432S120000
Reexamination Certificate
active
06285290
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is broadly concerned with improved self-cleaning ovens including an assembly to control the duration of the high-temperature oven cleaning cycles. More particularly, the invention pertains to such ovens, cycle controlling assemblies and methods wherein a parameter of at least a portion of the smoke generated during an oven cleaning cycle is measured and the duration of the cleaning cycle is determined in response to such measurement.
2. Description of the Prior Art
Many household and industrial ovens are equipped with self-cleaning cycles. When an oven is soiled, the user initiates a cleaning cycle, which involves heating of the oven to a very high temperature (e.g., 800° F.) so as to sublimate the oven contaminants. Conventional cleaning cycles operate for a preset period of 2-4 hours so as to insure that all such contaminants are removed from oven surfaces. During the course of a cleaning cycle, smoke is generated as the contaminants char and are sublimated. Usually the period of greatest smoke is during the initial thirty minutes or so of a cycle. Thereafter, smoke production tails off and becomes less prevalent.
A problem with conventional self-cleaning ovens is that the cleaning cycle is conducted for a preset period, regardless of the amount of soil and contaminants in the oven. Thus, the same amount of high temperature operation is carried out for a heavily or lightly soiled oven. This not only unnecessarily takes the oven out of service for longer than may be necessary, but also wastes significant energy.
There is accordingly a need in the art for improved self-cleaning ovens which will terminate an oven cleaning cycle after different periods of heating, in a manner commensurate with the level of soil and contaminants in the oven.
SUMMARY OF THE INVENTION
The present invention overcomes the problems outlined above and provides an oven cleaning cycle time-controlling assembly for use with self-cleaning ovens. The cycle time-controlling assembly of the invention operates by measuring a parameter of at least a portion of the smoke generated during an oven cleaning cycle, and by ascertaining the appropriate cycle duration in response to such measurement.
The preferred controlling assembly of the invention includes a sensing chamber together with a delivery system (e.g., a passageway) communicating the oven interior and the sensing chamber in order to convey at least a portion of the smoke evolved during the cleaning cycle to the sensing chamber. A smoke detector is associated with the sensing chamber in order to measure the smoke parameter of interest. Advantageously, the smoke detector is a conventional infrared smoke detector which is coupled with an electronic controller, in order to measure the a parameter of smoke generated during at least a portion of the cleaning cycle.
An on-off valve may be interposed within the delivery system between the oven and chamber and is also coupled with the controller. During normal oven usage, the valve is closed so as to prevent passage of oven gas to the measuring chamber. The valve is opened during the course of the cleaning cycle to allow passage of oven gas and smoke to the measuring chamber. Also, an in-line smoke filter may be interposed in the delivery system to remove the largest smoke particles. This reduces the rate of smoke contamination of the sensor chamber and other components.
REFERENCES:
patent: 3809913 (1974-05-01), Prellwitz
patent: 4351701 (1982-09-01), Bauer
patent: 4557203 (1985-12-01), Mainord
patent: 5826520 (1998-10-01), Mainord
patent: 6046441 (2000-04-01), Daffron
Pepper Hamilton LLP
SPX Corporation
Wu Daniel J.
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