Combustion – Mixer and flame holder
Reexamination Certificate
1997-10-20
2001-10-09
Clarke, Sara (Department: 3743)
Combustion
Mixer and flame holder
C126S0390BA, C239S555000
Reexamination Certificate
active
06299436
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to sealed cooktop burners including primary and secondary air passages, preferably throughout a plurality of burner head fingers covered by a burner cap.
DESCRIPTION OF THE PRIOR ART
Many previously known cooktop burners provide a limited flame area. Typically, the burners are circular and form a ring of flame which can engage the bottom of a utensil only at a limited area. Moreover, the flame tends to spread outwardly towards the outer edges of the utensil, whereby the central portion of the utensil within the ring may be relatively cooler than the remaining surface area, and particularly, cooler than the area constantly subjected to contact with the flame. Although some previously known burners have been provided with elongated extensions in order to expose burner ports to various positions along the bottom of the cooking utensil, these previously known configured burners were exposed to leakages from the cooking utensil. Such leakages may cause blockage of burner ports and further contribute to uneven heat distribution over a burner.
Although ring burners have been covered with caps in order to avoid exposure of the burner ports to clogging, the radially expanded cap distributes the flame ring wider, and thus contributes to the heating differential at the center of the cooking utensil over the center of the burner. Moreover, while capped burners are often raised above a supporting surface so that secondary air can contribute to the flame production as the primary flow of fuel and air mixture passes through the burner ports, recent cooktop innovations have lowered the burner so as not to expose a protruding, interfering surface above the cooktop surface of the appliance. However, lowering of the burner in the cooktop interferes with the free flow of secondary air near the burner ports that receive and discharge a primary fuel and air mixture. In addition, cooktop designs that provide sealed burner openings restrict access to secondary air within the appliance and prevent its use as secondary bypass air near the burner ports.
SUMMARY OF THE INVENTION
The present invention overcomes the above-mentioned disadvantages by providing a configured, capped burner that reduces the heating differential across the bottom of a heating utensil without exposing the burner ports to clogging from leakage that may occur from a cooking utensil. In addition, the present invention provides passages for secondary air, as well as passages for primary air, and the arrangement of ports does not interfere with the sealing of the burner opening in the cooktop. Moreover, the present invention provides a low profile burner configuration for use in a sealed cooktop providing easier maintenance and more efficient heating than previously known cooktops for cooking appliances.
In general, the burner comprises a burner head, including a chamber enclosed by a peripheral wall and a plurality of burner ports communicating between the chamber and the exterior of the head. Preferably, the burner is configured with a plurality of fingers and a cap extends over the burner head covering the ports in the burner head. In addition, a burner base supports the burner in a cooktop opening, preferably in sealing engagement with the cooktop panel. A plurality of bypass ports between the burner head and at least one of the burner cap and the burner base provide secondary air flow to aid flame propagation.
In the preferred embodiment, a star-shaped burner includes five fingers, each of the fingers being provided with a plurality of burner ports covered by the cap and in fluid communication with the chamber. A venturi port in the chamber receives a venturi tube communicating below the burner with a gas supply jet. Preferably, the gas supply jet is carried by a jet holder beneath the sealed surface in an enclosure wall in the cooktop appliance. In addition, the venturi tube cooperates with adjacent structure to couple a plurality of ports at the lower end of the burner head with secondary air through a bypass passageway, preferably through openings in a mounting plate. The burner base is sealingly engaged in an opening on the cooktop to seal the low profile burner in position on the cooktop surface.
The present invention also provides low profile burners with secondary air bypass capability intended for use in sealed burner cooktops where ambient air cannot be provided in sufficient quantities to support proper flame and ignition at all burner ports throughout the configuration of the cap. In addition, the present invention provides configured burners that reduce the area of the heat gradient and permits greater control of heat application to the bottom of the cooking utensil.
REFERENCES:
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patent: 4773383 (1988-09-01), Le Monnier de Gouville et al.
patent: 5133334 (1992-07-01), Riehl
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patent: 5490778 (1996-02-01), Meijer
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EP 0 581 655 A (Europ Equip Menager) Feb. 2, 1994, 5 pages, see abstract; figure 2.
DE 93 18 510 U (Elektro Gas Armaturen; Krebsoege GmbH Sintermetall (DE)) Jul. 28, 1994, 8 pages, see p. 5, paragraph 1; figures.
FR 2 701 542 A (Soreman) Aug. 19, 1994 23 pages, see abstract.
EP 0 491 580 A (Gaz De France) Jun. 24, 1992, 7 pages.
Brooks & Kushman P.C.
BSH Home Appliances Corporation
Clarke Sara
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