Combustion – Separately supplied or controlled – physically related flame... – Coaxial
Reexamination Certificate
2001-01-26
2001-12-04
Price, Carl D. (Department: 3743)
Combustion
Separately supplied or controlled, physically related flame...
Coaxial
C431S278000, C431S354000, C431S266000, C126S0390BA, C126S0390BA, C239S562000
Reexamination Certificate
active
06325619
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to improvements made to gas burners with multiple gas rings, designed to be mounted on a top plate of a cooking appliance, in particular for domestic use, and which comprises a first, central burner having a ring for peripheral flames and at least a second, annular burner surrounding the central burner at a distance therefrom and having at least one gas ring.
Such burners are used when a high heating power is required and/or, in conjunction with respective gas supply devices for central and annular burners, if the heat output needs to be modulated in terms of where and when it is applied (for example in Asian cooking).
DESCRIPTION OF THE PRIOR ART
Multiple ring burners are known which have a central burner with a gas ring and an annular burner with an outer gas ring or with two, respectively inner and outer gas rings.
However, the structure of these burners is not conducive to securing the degree of safety currently sought, particularly when it comes to preventing the flames from extinguishing and also in terms of compactness, in particular vertical.
SUMMARY OF THE INVENTION
Accordingly, the objective of the invention is to propose a multiple-ring gas burner of an improved type, with a structure designed to impart a degree of safety in keeping with modern requirements whilst remaining simple to manufacture and involving a minimum number of component parts, and which additionally is of a relatively low vertical height making it suitable for mounting both on a conventional cooker and on a cooking hob.
To these ends, the invention proposes a burner as outlined above, which is characterised in that it comprises:
a burner body designed to be fixed to the top plate, on the bottom thereof, and comprising:
a first gas inlet and, communicating therewith, a first gas injector, the axis of which is upwardly directed,
a second gas inlet and, communicating therewith, a second gas injector having a substantially horizontal axis and disposed facing a convergent-divergent pipe forming a Venturi which extends across at least the greater part of the transverse extension of the burner body, said pipe communicating, at its end opposite the second injector, with a substantially vertical well open at the top;
an outer burner head supported, by support means inserted in a cut-out section of said top plate, by said burner body, said burner head comprising:
a substantially annular chamber provided with passages for flames at least around one side and having an opening in its base disposed facing said substantially vertical well of the burner body,
a central region having a central, vertical recess, and
ports disposed between said annular chamber and said central region,
said support means for the outer burner head being designed so that said burner head is disposed above and at a distance from the top plate, forming in conjunction therewith an annular space surrounding said central region, said support means having lateral recesses providing a communication between said central recess of the central region and said annular space;
an inner burner head designed to be centrally supported by said outer burner head facing said central recess of the central region, said inner burner head having a central well directed coaxially with the axis of said first gas injector.
Based on the adopted structure, a burner with multiple gas rings is produced in which all the primary air needed to operate the first, central burner and the second, annular burner is delivered respectively to the vicinity of the first and second gas injectors via paths located exclusively above the top plate of the cooking appliance; to this end, the primary air penetrates the annular space defined between the outer burner head and the top plate, passes through the lateral recesses of the support means of the outer burner head and penetrates the burner body, where it is mixed with the jet of gas from the first injector supplying the central burner, whilst additionally passing from said above-mentioned annular space directly via a lateral opening provided for this purpose, towards the inlet of the horizontal convergent-divergent pipe, where it is mixed with the jet of gas from the second injector to supply the outer burner.
Similarly, all the secondary air supplying the flames arrives via the top of the top plate; this secondary air is made up in part of the ambient air surrounding the burners (annular, outer ring of the second burner; central ring of the first burner), and in part by a fraction of the air penetrating the annular space defined by the outer burner head and the top plate, this fraction of air passing via said ports between the two central and annular burners and supplying the flames of the inner ring of the annular burner and, in part, the flames of the central burner.
Accordingly, the multi-ring burner has structural features designed to secure a supply of air, both primary and secondary, such that use of the subjacent parts of the cooking appliance does not affect the flames, even on a low light, in other words, prevents the flames from being extinguished, in particular on a low light, if the door of a subjacent oven is closed violently.
Furthermore, the horizontal Venturi design supplying the outer burner head and the upwardly directed Venturi made partially in a tubular design and partially in a radially horizontal design, as will be explained below, are such that a burner can be made with a relatively low height, suitable for mounting both on a cooker and on a cooking hob.
In a first possible embodiment, which has the advantage of being simple, the central well of the inner burner head is directed substantially vertically and the axis of the first injector is substantially vertical.
However, in another embodiment which is of interest because it provides a significantly longer Venturi and hence more effective mixing of the air and gas, the central well of the inner burner and the first injector substantially coaxial therewith are inclined by approximately 15 to 20° relative to the vertical.
In an example of an embodiment as applied to domestic cooking appliances, the gas burner has a single annular chamber in the outer burner head, which is provided with passages for flames on both sides and the second, annular burner has two gas rings, the burner being of the type with three gas rings.
In one structurally simple embodiment which requires a reduced number of forged parts, the support means of the outer burner head are integral with said outer burner head and are provided in the form of a skirt projecting down below the bottom of said head and a shoulder surrounding the central recess of the central region of said burner head. With the same concern in mind, the annular chamber of the outer burner head may be closed at the top by a removable annular cover placed on the lateral walls of the chamber.
Similarly, in order to provide the first, central burner with a Venturi of sufficient length, the central well of the inner burner head has, for practical purposes, a section which decreases in an upward direction, thereby forming a first, tubular Venturi section, and the top surface of the inner burner head surrounding the top orifice of the central well defines, in conjunction with a removable cover surmounting it, a radial, annular, divergent section forming a second, radial, annular Venturi section.
In one practical embodiment which enables the burner to be readily adapted to commercial requirements relating to the selling of cooking appliances, the outer burner head may be surrounded at the bottom by a downwardly inclined, peripheral skirt and said peripheral skirt is designed as a removable part.
Furthermore, to avoid increasing the number of accessories needed to operate the burner and thereby reduce the overall cost of the burner, the burner has a thermocouple to detect the presence of flames and/or an electric ignition member and said thermocouple and/or ignition member co-operate with the central burner.
Due to its structure, a burner designed as proposed by the invent
Larson & Taylor PLC
Price Carl D.
Sourdillon
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