Turn-off control circuit for self-cleaning ovens
First Claim
1. A self-cleaning thermal oven and control therefor, comprising:
- a thermal cooking oven cavity;
electrically-energizable means within said oven cavity for thermally heating the interior of said cavity to a temperature at least high enough to pyrolyze cooking soil within said cavity and convert said soil to an effluent capable of flowing out of said oven cavity;
a smoke eliminator comprising a passage, extending from the interior of said oven cavity to external atmosphere;
an electrically-energizable smoke eliminator heater disposed to heat effluent which flows from said thermal oven cavity and through said passage, said smoke eliminator heater being operable to oxidize partially pyrolyzed components in the effluent produced by said oven heater means;
a reducing gas sensor fixed relative to said smoke eliminator passage at a position before the end of said passage furthest from said oven cavity and exposed to at least a portion of said effluent which flows from said oven cavity and through said passage, said reducing gas sensor producing an electrical output related to the concentration of pyrolyzed products in said effluent; and
electrical control means coupled to said oven thermal heating means for connecting and disconnecting power thereto, said reducing gas sensor being electrically coupled to said electrical control means to cause said electrical control means to disconnect power from said oven thermal heating means responsive to an output of said reducing gas sensor which is indicative of the completion of the oven cleaning process and of a pyrolyzed product concentration in said effluent which is less than a given amount.
1 Assignment
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Accused Products
Abstract
In a cooking oven which is cleaned by pyrolyzation of soil within the oven cavity and has a smoke eliminator duct extending through the oven wall, with a smoke eliminator heater disposed adjacent to the duct inlet, a reducing gas sensor is mounted either adjacent to the oven end of the smoke eliminator duct or within the smoke eliminator duct near its discharge end. An electrical relay or microcomputer control is coupled between the gas sensor and the heater to initially heat the oven interior and to later deenergize the heater when the reducing gas sensor output indicates a desired oven condition. The oven heaters are temporarily deenergized when the gas sensor output indicate a smoke eliminator overload. If the gas sensor is mounted in the smoke eliminator duct, the smoke eliminator heater may be deenergized toward the end of the cleaning cycle, so that the effluent is not affected by the smoke eliminator heater before reaching the gas sensor. Plural smoke eliminator heaters are also disclosed to enable increase of heater power during the early cleaning stages and reduction of the heater power during the later cleaning stages.
56 Citations
20 Claims
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1. A self-cleaning thermal oven and control therefor, comprising:
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a thermal cooking oven cavity; electrically-energizable means within said oven cavity for thermally heating the interior of said cavity to a temperature at least high enough to pyrolyze cooking soil within said cavity and convert said soil to an effluent capable of flowing out of said oven cavity; a smoke eliminator comprising a passage, extending from the interior of said oven cavity to external atmosphere; an electrically-energizable smoke eliminator heater disposed to heat effluent which flows from said thermal oven cavity and through said passage, said smoke eliminator heater being operable to oxidize partially pyrolyzed components in the effluent produced by said oven heater means; a reducing gas sensor fixed relative to said smoke eliminator passage at a position before the end of said passage furthest from said oven cavity and exposed to at least a portion of said effluent which flows from said oven cavity and through said passage, said reducing gas sensor producing an electrical output related to the concentration of pyrolyzed products in said effluent; and electrical control means coupled to said oven thermal heating means for connecting and disconnecting power thereto, said reducing gas sensor being electrically coupled to said electrical control means to cause said electrical control means to disconnect power from said oven thermal heating means responsive to an output of said reducing gas sensor which is indicative of the completion of the oven cleaning process and of a pyrolyzed product concentration in said effluent which is less than a given amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A process for controlling the self-cleaning of a cooking oven cavity, comprising the steps of:
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heating the interior of the oven cavity to a pyrolyzing temperature of about 900°
F.;heating a smoke eliminator heater, disposed adjacent to a smoke eliminator duct extending from the oven cavity to room atmosphere, to a pyrolyzing temperature for further pyrolyzing effluent issuing from the oven cavity and flowing through the smoke eliminator duct; providing a reducing gas sensor at a position fixed relative to the smoke eliminator passage and before the end of the passage furthest from the oven cavity; electrically measuring the partial pyrolytic product content of the effluent flowing through the duct by causing the effluent to flow over the reducing gas sensor; and electrically terminating the heating of the oven cavity when the pyrolytic content of the effluent measured by the reducing gas sensor indicates an acceptable oven-clean condition. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification