EP1781989B1

EP1781989B1 - Gas burner with multiple flame rings

Info

Publication number: EP1781989B1
Application number: EP05773155.6A
Authority: EP
Inventors: Carlo Paesani; Girolamo Tommaso Emiliani
Original assignee: Defendi Italy SRL
Current assignee: Defendi Italy SRL
Priority date: 2004-07-09
Filing date: 2005-06-24
Publication date: 2015-12-09
Anticipated expiration: 2025-06-24
Also published as: ITVE20040031A1; CN1985126B; WO2006005428A1; BRPI0513197B1; PL1781989T3; MXPA06015017A; EG25057A; EP1781989A1; BRPI0513197A; CN1985126A; ES2564581T3

Description

The present invention relates to a burner with multiple flame rings.
With burners having several concentric flame rings controlled by a single tap, i.e. so-called double or triple ring burners, there is an increasing tendency to require high powers for more rapid cooking. At the same time these burners must maintain very small height dimensions to enable them to be used both on cookers and on modern built-in hobs of only 30-40 mm in height.
As in the case of all burners, their injector has to be replaced if converting to use a different gas, this being done from the top without opening the hob.
Another essential requirement of these burners is that the primary and secondary air required for burner operation must be withdrawn only from the outside of the appliance. This enables the hob to be sealed together with the burner, so that any food spilled from pans can in no way enter the hob, and in addition the opening and closure of doors of a cabinet or oven positioned below the hob does not prejudice proper burner operation.
To satisfy these requirements. currently available triple ring burners are substantially constructed on the radial venturi concept, as is the case with all other smaller burners, i.e. auxiliary, semi-fast and fast.
In this type of burner the venturi is formed from a vertical first frusto-conical converging portion and a horizontally extending second radial diverging portion.
This solution enables very shallow compact burners to be developed but, in the case of double or triple ring burners, the constructional characteristics limit the horizontal radial length of the venturi. This means than the developed power is relatively low, this in the case of heavy gases being a considerable limitation, especially in those markets where these burners are most used, such as Asia and the Middle East, where the requirement for high power is strongest while at the same time heavier liquid gases are very widespread.
In other solutions the gas is fed to a number of injectors combined with radial venturis to divide the gas among several venturis and hence seek to develop more power, but these solutions also have limitations.
The horizontally extending radial part, essential for burner operation, must necessarily have a certain surface which extends towards the burner interior and of necessity creates projections towards the burner interior which finish by limiting the secondary air within the internal part between the two burner portions, hence the internal burner must be of very small dimensions and with few flames.
These solutions are constructionally very complicated and costly and in no case do they attain the power target required by today's market.
US-2001/0010897 A1 discloses a gas burner with multiple gas rings comprising a burner body mountable underneath a top plate, with a cut-out section, of an appliance and incorporating a first, upwardly directed gas injector and a second gas injector followed by a horizontal tubular Venturi opening into a vertical well, an outer burner head seated on the body through the cut-out section and spaced at a distance above the plate and provided with an angular chamber open above the well and having one or two rows of orifices for flames; and an inner burner head shaped so as to have a radial divergent coaxially supplied by the first injector through a recess located at the centre of the head.
An object of the invention is to avoid the aforesaid drawbacks by providing a burner with multiple flame rings, which is of high performance and power while being of very low cost, and not requiring the use of costly special two-way valves such as dual burners, but merely a simple tap.
This and other objects which will be apparent from the ensuing description are attained according to the invention by a multiple rings gas burner with flames distributed over a substantially circular inner portion and over an outer portion as claimed in claim 1.
The present invention is further clarified hereinafter in terms of a preferred embodiment and a variant provided and described with reference to the accompanying drawings, in which:

Figure 1 is a plan view of the assembled burner without the caps,
Figure 2 is a plan view of the cup formed by the two assembled shells,
Figure 3 is a plan view of the complete burner,
Figure 4 is a section therethrough on the line IV-IV of Figure 3,
Figure 5 is a section therethrough on the line V-V of Figure 3,
Figure 6 is a plan view of the lower shell of the injector holder cup, and
Figure 7 shows a variant of a burner.

As can be seen from the figures, the burner of the invention comprises substantially an injector holder cup 1, known hereinafter simply as a cup, consisting of a lower shell 2 and an upper shell 3 joined together, and a flame divider 4.
Said cup presents a perimetral edge 9 on which the hob 12 of the cooking appliance is fixed by screws 11.
In the lower outer part a gas inlet 10 is present, connected to the burner control tap by a tube.
The inlet 10 continues internally with a conduit 15 on which the horizontally disposed injector 14 is housed: the head of the injector 14 projects into a cavity 27 open only upwards.
Opposite the injector 14 there extends a horizontal venturi conduit 26 formed from a first converging portion 16, a second more or less constant portion 17, and a third diverging portion 18.
The final diverging portion 18 of the venturi 26 leads to a conduit which branches into two sections 33 and 34 terminating in two opposing chambers 28 which extend externally towards the perimetral edge of the cup and internally towards the central region close to the venturi 28
Said chambers 28 upperly present an aperture 19 towards the outside, and an aperture 35 towards the inside.
The flame divider 4 is preferably formed as a single piece, consisting of a central circular inner portion and a more or less annular outer portion.
The outer portion presents an outer edge 30 in which a series of apertures 5 are provided for passage of the air/gas mixture, an inner edge 21 in which a series of apertures 22 are provided, and a base 13.
In the base 13 two opposing apertures 6 are present, externally to which there is a wall 23.
The burner outer portion is closed upperly by a closure element 29 or outer cap.
The circular inner portion of the flame divider presents on its lower face an edge 7 which defines a cavity 24 open centrally upwards via a hole 37 leading into a chamber 31 defined circumferentially by an outer edge 25, lowerly by a base 40, and upperly by a closure element 38 or central cap. Apertures 41 for exit of the air/gas mixture are provided in the outer edge 25.
The edge 25 of the circular inner portion continues downwards and has associated with it a flange 8, the upper face 20 of which defines, with the outer edge 25 and the edge 21 of the outer portion, an annular cavity 39.
The flange 8 of the circular inner portion is joined to the edge 21 of the outer portion by connection sectors 32, which between them define apertures 36.
The flame divider 4 is supported and centered on the cup 1 by appropriate means 44 and defines an outer annular area which, via the apertures 36, supplies the annular cavity 39 with the secondary air required for creating the flames present on the central circular inner portion of the flame divider 4 and the flames present on the inner edge 21 of the outer portion of the flame divider 4.
On its lower face the flame divider 4 presents projecting fins 49 which, when the flame divider rests in its seat on the cup 1, close the edge 45 to define an outward aperture 46 for passage of primary air 43.
The burner of the invention operates in the following manner:

From the inlet 10 the gas reaches the injector 14 and on leaving entrains primary air 43 upperly through the aperture 46. The gas/air mixture then enters the venturi 26 and at its end splits equally through the two sections 33, 34 which return it rearwards in the opposite direction.

Said mixture then reaches the opposing chambers 28, most of it then flowing through the apertures 19, which are in correspondence with and in contact with the apertures 6 of the outer portion of the flame divider 4, and into the annular outer portion thereof.
From there the mixture is distributed and emerges outwards from the apertures 5 to create the outer flame ring, and towards the burner interior from the apertures 22 to create the second flame ring.
During this stage the path of the terminal part of the venturi 18 to the two sections 33, to the chambers 28 and to the entrance of the flame divider 4 contributes to optimal mixing of the air/gas mixture. The walls 23, positioned between the apertures 6 through which the mixture enters the outer portion of the flame divider and its edge 30, prevent excessive emergence in this area, which could cause flame unbalance.
The rest of the mixture flows through the apertures 35 into the chamber 24, defined lowerly by the cup and upperly by the central portion of the flame divider 4, and then through the hole 37 to enter the chamber 31 which is upperly closed by the inner cap 38. From there, said mixture leaves through the slits 41 provided in the edge 25 of the circular inner portion of the flame divider 4, to hence create the inner flame ring of the burner.
The secondary air 42 required for combustion of the air/gas mixture leaving the slits 41 of the inner portion of the flame divider 4 and the slits 22 of its outer portion is available in the annular cavity 39 which is fed with air through the apertures 36 which connect the outer region to said annular cavity 39. In this manner the flame divider 4 rests and is centered on the cup 1 to form a seal on said cup: the result is that if liquids spill from a pan, said liquids tend to emerge outside the hob 12, as the face 20 is inclined slightly downwards. At the same time the edge 45 and the fins 49 mean that said spilt liquids do not enter the chamber 27 housing the injector 14.
In Figure 7 two linear venturis 26 are provided, each associated with an injector 14 both connected to the burner gas inlet 10, in order to further increase burner power.

Claims

A multiple rings gas burner to be installed on a hob, with flames distributed over a substantially circular inner portion and over an outer portion of a flame divider (4), the circular inner portion and the outer portion separated by an annular secondary air cavity (39),
with the following combination:
- it presents a single gas inlet in communication with at least one injector (14) disposed horizontally,

- with said at least one injector (14) there is associated a venturi conduit (26) of linear extension disposed horizontally,

- the primary air required for burner operation comes from the top external to the hob,

- the secondary air required for burner operation comes from the top external to the hob

- the air/gas mixture is supplied to both the outer and circular inner portion of the flame divider (4) via the same linear venturi conduit (26).
A burner as claimed in claim 1, characterised in that the outer portion of the flame divider (4) consists of an annular body presenting at least two series of flame slits.
A burner as claimed in claim 1, characterised in that the air/gas mixture enters the outer portion of the flame divider (4) through at least two apertures (6).
A burner as claimed in claim 1, characterised in that the flame divider (4) when resting on then cup (1) defines two separate sectors for primary air flow to the injector and for secondary air flow to the central inner part (39) of the flame divider (4).
A burner as claimed in claim 1, characterised in that the air/gas mixture reaches the central part of the flame divider (4) through an aperture (37) located at the centre of the chamber (31) of said central part.
A burner as claimed in claim 1, characterised in that the linear venturi conduit consists of a first converging portion (16), a second substantially rectilinear portion (17) and a third diverging portion (18), all lying on the same axis.
A burner as claimed in claim 1, characterised in that the flame divider (4) is in one piece.
A burner as claimed in claim 1 , characterised in that the flame divider (4) is in two pieces.
A burner as claimed in one of the preceding claims, characterised in that flame slits are also provided on the closure caps (29, 38).
A burner as claimed in claim 1, characterised in that the venturi conduit opens into an upperly open chamber in communication with both the circular inner portion and outer portion of the flame divider (4).