FIELD OF TECHNIQUE

The present invention relates to a gas burner to be mounted on a hob, preferably on a built-in hob. Furthermore, the present invention relates to an injector holder for a gas burner to be mounted on a cooktop, preferably on a built-in cooktop.

STATE OF THE ART

Known burners with multiple flame rings, of the type also called "multiring", commonly comprise an injector holder, a base positioned on the injector holder and at least one cover positioned on the base and defining with it a mixing and distribution chamber for the air-gas mixture.

The injector holder is commonly made of die-cast aluminum and is provided with means for its fastening to the hob. Two or more injectors are mounted on the bottom of the injector holder, generally with a vertical axis, which are fluidly connected to the gas feed inlet.

The base is also made of die-cast aluminum and is provided with two or more vertical axis ducts, each of which is coaxial and faces a corresponding injector mounted on the injector holder.

Furthermore, the base is configured so as to define an internal central distribution chamber and an external annular distribution chamber, which is positioned externally around the internal central distribution chamber and is separated from the latter by a substantially annular cavity. A first vertical duct opens into the internal central distribution chamber, while at least one further vertical duct opens into the external annular distribution chamber.

The base itself also acts as a flame divider and, in particular, on the edge and/or external wall of the internal central distribution chamber there are doors for the exit of a first ring of flames, while on the edge and/or external wall of the distribution chamber external annular doors are obtained for the escape of a second crown of flames. Furthermore, in some embodiments, doors are formed on the edge and/or inner wall of the outer annular distribution chamber for the release of a third ring of flames.

The lid or lids, commonly pressed in sheet metal, are placed on the base so as to close the internal central distribution chamber and the external annular distribution chamber at the top.

In particular, in known solutions, the injector holder generally has a central cavity and two lateral cavities. In more detail, in the known solutions in which the suction is provided only from above the hob, the aforementioned side cavities of the injector holder - which are then fluidically connected with the external annular distribution chamber, from which the second e/ or the third crown of flames - they are closed both on the bottom and on the sides and have particularly large dimensions, much larger than the central cavity, and this precisely to allow the intake of a quantity of primary air from above the hob sufficient to create an air-gas mixture suitable for supplying the external distribution chamber and therefore suitably feeding the second and/or third crown of flames

Furthermore, around the upper edges of the aforementioned three cavities in which the injectors are mounted, the injector holder extends radially with an enlarged crown such as to give the injector holder itself a substantially circular plan shape. Furthermore, at the external perimeter of the enlarged crown, suitable seats or means are obtained for fixing the injector holder itself to the hob.

These known solutions, although appreciated, are not fully satisfactory since the injector holder thus made is particularly heavy and cumbersome, especially in width, as well as being particularly expensive to make, both in view of the quantity of material required to make it and because, in a single molded by die-casting, it is possible to obtain only a few pieces (generally only two).

Furthermore, the large width of known injector holders also necessarily imposes installation constraints on hobs/cooking applications, thus inevitably preventing their use on hobs or cooking applications of small dimensions or where there are particular needs in terms of encumbrances.

Furthermore, in some known solutions, the profile of the edge and of the internal side wall of the annular distribution chamber is irregular, thus leading the burner to have a particular, non-traditional and not always welcome aesthetic appearance. Furthermore, in these solutions, to close the chamber at the top which has an internally irregular profile, it is not possible to use the traditional and inexpensive closing lids with a regular annular shape.

OBJECTS OF THE INVENTION

The object of the invention is to propose a gas burner to be installed on a hob which overcomes, at least in part, the drawbacks of traditional solutions.

Another object of the invention is to propose a gas burner which has a high thermal power while having an injector holder with particularly compact dimensions, particularly in width.

Another object of the invention is to propose a gas burner which can be assembled and disassembled extremely easily, quickly and safely.

Another object of the invention is to propose a gas burner which, over time and with the inevitable accumulation of dirt following use, can be assembled and disassembled extremely easily, quickly and safely. Another object of the invention is to propose a gas burner which has a particularly pleasant overall aesthetic effect.

Another object of the invention is to propose a gas burner which has a reduced number of components.

Another object of the invention is to propose a gas burner which can be obtained with extremely low production costs.

Another object of the invention is to propose a gas burner which can be mass- produced quickly and efficiently.

Another object of the invention is to propose a gas burner which has an alternative and/or improved characterization, both in constructive and functional terms, with respect to the traditional ones.

Another object of the invention is to propose a gas burner which meets high standards, both functionally and aesthetically, and at the same time has an affordable cost, thus allowing the possibility of its diffusion on a large scale.

Another object of the invention is to propose a gas burner of simple construction and low cost.

Another object of the invention is to propose an injector holder which is more compact and cheaper than the traditional ones.

Another object of the invention is to propose an injector holder which is lighter and/or has a smaller footprint than traditional ones.

Another object of the invention is to propose an injector holder which can be manufactured simply, quickly and with limited costs.

Another object of the invention is to propose a gas burner or an injector holder which can be easily installed even in hobs or cooking applications of small dimensions or, in general, where there are problems or particular requirements in terms of dimensions. SUMMARY OF THE INVENTION

All these objects, both alone and in any combination thereof, and others which will apparent from the following description are achieved, according to the invention, through a gas burner with the characteristics of claim 1 or with an injector holder with the characteristics of claim 12.

DESCRIPTION OF THE FIGURES

The present invention is hereinafter further clarified in some of its preferred embodiments shown for purely exemplifying but non-limiting purposes with reference to the enclosed sheets of drawings, in which:

Figure 1A shows an exploded perspective view of a burner according to the invention, Figure 1B shows a view of the burner of fig. 1A, in the assembled condition, and sectioned with a vertical section plane which passes through all three cavities of the nozzle holder along the direction of longest development of the nozzle holder,

Figure 1C shows a view of the burner of fig. 1A, in the assembled condition, and sectioned with a plane of vertical section which is perpendicular to that of FIG. 1 B and which only crosses the central cavity of the injector holder along the shorter direction of development of the injector holder itself,

Figure 2A is a top perspective view of only the injector holder according to the invention and used in the burner of fig. 1A,

Figure 2B is a bottom perspective view of the injector holder of fig. 2A,

Figure 3A is a top perspective view of only the base of the burner of fig. 1 A,

Figure 3B is a bottom perspective view of the base of fig. 3A,

Figure 4 is a plan view of a cooking hob with the injector holder of fig. 1 A and 2A,

Figure 5 is a plan view of the burner of fig. 1 A,

Figure 6 is a plan view of the burner of fig. 1A and with also represented the crowns of flames.

DETAILED DESCRIPTION OF THE INVENTION AND SOME PREFERRED EMBODIMENTS

As can be seen from the figures, the gas burner 2 according to the invention comprises a base 4, which can be positioned on an injector holder 6, and at least one lid 8 which can be positioned above the base 4.

Conveniently, the gas burner 2 is of the type suitable for being mounted on a hob 90, preferably on a built-in hob. Conveniently, the burner 2 is suitable for heating pans or, in general, cooking utensils (such as, for example , plates, grills, grill pans, saucepans, etc.).

Preferably, for example in the embodiments shown, the base 4 acts as a flamedivider. Conveniently, in other possible embodiments (not shown here), the division of the flames can be carried out by the covers 8 alone, or it can be carried out both by the base 4 and by the corresponding covers 8.

Conveniently, said burner 2 consists exclusively of the base 4, of the injector holder 6 and of at least one lid 8, preferably of two lids 8' and 8".

The injector holder 6 has a narrow and elongated shape. More specifically, by "elongated" shape we mean that the development/extension along an X direction (ie in length) is different and greater than the development/extension along a Y direction (ie in width) which is perpendicular to the X direction where, moreover, the X and Y directions are both perpendicular to a Z direction which completes the directions of a Cartesian triad and which corresponds to the positioning and overlapping direction of the base 4 on the injector holder 6 and also of the cover 8 on the base 4. in detail, in other words, the lid 8, the base 4 and the injector holder 6 are mutually superimposed along the direction Z. Conveniently, the direction Z corresponds to a substantially vertical direction.

The development of the injector holder 6 along the X direction is much greater than that along the Y direction and, in particular, the development of the injector holder 6 along the Y direction is equal to or less than about 1/3 of the development of the injector holder itself along the direction x.

Preferably, the maximum development of at least one of the three cavities 32', 32", 32"' (understood as the distance between the opposite edges which delimit the respective cavity) along the Y direction is equal to or less than about 1/3 of the distance between the outermost edges of the two side cavities 32" and 32'" along the X direction.

The base 4, which rests on the injector holder 6, comprises:

- an internal chamber 10 for mixing and/or distributing a mixture of air and gas, thus feeding a first ring of flames 12, and

- an external annular chamber 20 for mixing and/or distributing a mixture of air and gas, to thus feed a second crown of flames 22 and/or a third crown of flames 24.

Conveniently, the base 4 is made in one piece.

As mentioned, the burner 2 comprises at least one lid 8 for closing said inner chamber 10 and said outer annular chamber 12. Preferably, said at least one lid 8 is pressed in sheet metal. Preferably, the lid 8 is entirely enamelled or at least in correspondence with its upper face intended to be visible.

Conveniently, the outer annular chamber 20 is separated from the inner chamber 10 - which is preferably positioned at the center of the base 4 - by an inner depressed area 13 with a substantially annular development. Suitably, furthermore, the outer annular chamber 20 and the inner chamber 10 are mutually connected by radial portions 14 which thus cross the inner depressed zone 13. Preferably, the radial connection portions 14 can be provided at the bottom of the inner depressed zone 13.

Preferably, in a possible embodiment represented in the figures, the outer annular chamber 20 and the chamber 10 are not in fluid communication with each other, however in some possible embodiments not shown here there could be radial channels crossing the internal depressed area 13 to fluidically connect the outer annular chamber 20 and the chamber 10.

Conveniently, the internal chamber 10 is provided with first doors 11 for the exit of a first ring of flames 12. In particular, the first doors 11 are formed on a cylindrical wall 15 which laterally and externally delimits the internal chamber 10, preferably in correspondence of the upper edge of said cylindrical wall 15.

Preferably, the outer annular chamber 20 is provided with second doors 21 for the exit of a second ring of flames 22. In particular, the second doors 21 are formed on an outer side wall 25 which externally delimits the outer annular chamber, preferably in correspondence of the outer upper edge of said outer side wall 25.

Preferably, the outer annular chamber 20 is provided with third doors 23 for the escape of a third ring of flames 24. In particular, the third doors 23 are formed on an internal side wall 26 which internally delimits the outer annular chamber, preferably in correspondence of the outer upper edge of said inner side wall 26.

Conveniently, the flames of the first crown 12 emerge in the depressed area 13 and are directed outwards, while the flames of the third crown 24 emerge in the depressed area 13 and are directed inwards.

Preferably, the burner 2 comprises two lids, and in particular a first lid 8' of circular shape for closing the internal chamber 10 and a second lid 8" of annular shape for closing the external annular chamber 20.

Preferably, in a possible embodiment not shown here, the burner 2 can comprise a single lid with an internal circular portion for closing the internal chamber 10 and an external annular portion for closing the external annular chamber 20, and in which further the inner circular portion and the outer annular portion are connected to each other by radial portions.

Conveniently, in more detail, the internal chamber 10 is delimited laterally by a cylindrical wall 15, at the bottom by a bottom surface, while at the top it is delimited and closed by the first lid 8' (or by the central portion of a single lid 8).

Conveniently, the first gates 11 are defined on the upper edge of the cylindrical wall 15.

Conveniently, the first doors 11 can comprise respective first main slots/holes and first secondary slots/holes, having different shapes and/or sizes.

Conveniently, in some possible embodiments, the first doors 11 comprise main or secondary hollows, which are obtained on the base 4 and which are open on the upper side to be thus closed by the lid 8. Conveniently, in some possible embodiments, the first doors 11 can include small through holes, closed on all sides of the passage section, obtained solely and entirely on the base 4, or small through holes, closed on all sides of the passage section, obtained solely and entirely on the lid 8. Preferably, inside the internal chamber 10 also emerges the upper section - preferably of truncated cone shape converging upwards - of a central duct 40' of the base 4, as better described hereinafter.

Conveniently, in more detail, the outer annular chamber 20 is defined laterally between an outer side wall 25 and an inner side wall 26, at the bottom by a bottom surface which joins the aforementioned two walls 25 and 26, while at the top it is delimited and closed by the second lid 8" (or from the outer annular portion of a single lid 8). Preferably, inside the outer annular chamber 20 the upper portions also protrude - preferably each having a truncated cone shape converging upwards - of two respective lateral ducts 40" and 40"' of the base 4, as better described below .

Conveniently, the second doors 21 are defined on the upper edge of the outer side wall 25 of the base 4. Conveniently, the second doors 21 can comprise respective second main slots/holes 21 and second secondary slots/holes 21 , having shape and/or dimensions between them different.

Suitably, the third ports 23 are defined on the upper edge of the internal side wall 26 of the base 4. Suitably, the third ports 23 can comprise respective third main slots/holes 23 and third secondary slots/holes 23, having shape and/or dimensions between them different.

Suitably, in some possible embodiments, the second doors 21 and/or the third doors 23 comprise main or secondary slots, which are obtained on the base 4 and which are open on the upper side to be thus closed by the lid 8. Suitably, in some possible embodiments, the second doors 21 and/or the third doors 23 can comprise small through holes, closed on all sides of the passage section formed solely and entirely on the base 4, or small through holes, closed on all sides of the passage section, obtained solely and entirely on the cover 8.

Conveniently, the first doors 11 , the second doors 21 and/or the third doors 23 can have the same or different shape and/or dimensions.

Preferably, the development of the injector holder 6 along the X direction substantially corresponds to the diameter of the base 4, while the development of the injector holder 6 along the Y direction is smaller than the diameter of the base 4. More preferably, the development of the injector holder 6 along the Y direction it is equal to or less than half the diameter in plan view of the base 4 (and in particular substantially corresponding to the diameter of the outer side wall 25). More preferably, the development of the injector holder 6 along the Y direction is equal to or less than about 1/3 of the plan diameter of the base 4 (and in particular substantially corresponding to the diameter of the outer side wall 25). The injector holder 6 is configured for and is intended to be applied in correspondence with at least one through opening intended to be made in a cooking hob 90 . Conveniently, the injector holder 6 is intended to be constrained to the cooking hob 90 and, preferably, to a built-in cooking hob.

Preferably, the injector holder 6 is configured to adhere from below to the sheet metal of a cooking hob 90 around said at least one through opening formed in said cooking hob.

The injector holder 6 comprises three concave elements, respectively 31', 31" and 3T", each of which delimits within it a corresponding cavity - respectively 32', 32" and 32'"

- in which a corresponding injector, respectively 33', 33" and 33'". Conveniently, the injector holder 6 is made in a single piece.

In particular, the injector holder 6 comprises:

- a central concave element 3T which defines inside it a corresponding central cavity 32' in which a corresponding central injector 33' is mounted,

- two side concave elements 31" and 31'", which respectively delimit inside them the side cavities 32" and 32'", in each of which a corresponding side injector 33" and 33'" is mounted.

Preferably, the three concave elements 3T, 31" and 3T" are substantially shaped like a well or cup.

Conveniently, the three concave elements 3T, 31" and 3T" are connected to each other at their bottom by a corresponding connecting section 38.

Conveniently, the central injector 33' is interposed between the lateral injectors 33" and 33'".

Conveniently, the three injectors 33', 33" and 33'" have a substantially vertical development (i.e. along the Z direction) and, in particular, the development axes of each injector 33', 33" and 33" ' are aligned along a Z direction.

Preferably, the axes of the three injectors 33', 33" and 33'" are parallel to each other.

Preferably, the axes of the three injectors 33', 33" and 33"' are side by side along the X direction.

Preferably, the three injectors 33', 33" and 33'", although being side by side along the X direction, can be mounted inside the respective cavities so as to be all substantially at the same height/dimension along the direction Z. Conveniently, in a possible embodiment not shown, the central injector 33' can be mounted at a height/dimension along the Z direction which is different (i.e. can be higher or lower) than that of the two lateral injectors 33 " and 33'" which instead are at the same height/dimension. Conveniently, the three injectors 33', 33" and 33"' are mounted inside a corresponding cavity 32', 32" and 32'" and, in particular, at the bottom wall of the corresponding cavity. Advantageously, on the bottom wall of each cavity 32', 32" and 32'" of the injector holder 6 the corresponding injector 33', 33" and 33'" with vertical development is mounted - preferably screwed.

The injector holder 6 comprises one and only gas inlet 30 which is in fluid communication with all three injectors 33', 33" and 33'". Preferably, the gas inlet 30 is intended to be associated with a standard single outlet valve (not shown). In particular, therefore, the burner 2 is of the "multiring" type in which all the crowns of flames 12, 22 and/or 24 are fed by a single gas source and are all regulated together in the same way. In more detail, the burner 2, and in particular its injector holder 6, is provided with a single gas inlet 30 and, therefore, is not of the "dual" type and, in particular, does not have two gas inlets controlled by a "dual" valve or by two corresponding valves.

Conveniently, the injector holder 6 internally comprises a gas supply conduit 34 which is fluidically connected to the single gas inlet 30 and to the three injectors 33', 33" and 33'". Conveniently, the feed duct 34' extends longitudinally substantially along the development direction X of the injector holder 6. Preferably, the feed duct 34 is positioned below the bottom wall of each of the three cavities 32', 32" and 32". Preferably, the feed duct 34 extends horizontally or substantially horizontally at the bottom of the injector holder 6. Preferably, the feed duct 34 is open at one end at the gas inlet 30 and communicates with the three injectors 33' , 33" and 33". Preferably, the feed duct 34 has a constant or slightly converging cross-section along its longitudinal development.

Conveniently, the three cavities 32', 32" and 32"' in which the gas comes out from the respective injectors 33', 33" and 33'" are fluidically separated from each other; in other words, the injector holder 6 is configured in such a way that, downstream of each injector 33', 33" and 33'", the gas which comes out of each injector into the corresponding cavity, in which the injector itself is housed, it does not mix and/or is not in fluidic communication with what comes out in the other two cavities . Conveniently, in the injector holder 6, downstream of each injector 33', 33" and 33'", there are no ducts or sections of fluid connection between the central cavity 32' and the side cavities 32" and 32'" , or viceversa. Preferably, downstream of the respective injectors 33', 33" and 33'", the three cavities 32', 32", 32'" are spaced apart and, in particular, there is a separation space between the central cavity 32' and each of the two lateral cavities 32" and 32'". Conveniently, downstream of the respective injectors 33', 33" and 33'", the walls delimiting said three cavities 32', 32" and 32"' are separate from each other and, moreover, said walls are not shared between the central cavity 32' and the lateral cavities 32" and 32'". Advantageously, this allows to have flows of primary air, for each of the three cavities, which are suitably separated from each other, to thus prevent the respective injectors 33', 33" and 33"' from rubbing against each other; essentially, this allows to avoid fluidic interference between the injectors 33', 33" and 33'" and between the primary air flows recalled by the three injectors 33', 33" and 33'" inside the respective 32', 32" and 32" cavities.

Preferably, there are spacer walls 49 between the walls of the central cavity 32' and each of the two lateral cavities 32" and 32'". Conveniently, the spacer walls 49 extend along the X and Y axes.

Conveniently, the three cavities 32', 32" and 32'" are substantially side by side along the X direction and, in particular, the central cavity 32' is interposed between the two side cavities 32" and 32'" .

Conveniently, the axes of the three injectors 33', 33" and 33'" are mutually parallel and directed along corresponding parallel Z directions.

Preferably, the injector holder 6 is configured in such a way that, when the base 4 is positioned on the injector holder 6, the latter is substantially contained within the maximum overall dimensions in plan of the base itself, i.e. substantially it does not protrude with respect to the overall dimensions in plan outermost (substantially defined by the outer side wall 25) of said base 4.

Conveniently, in some possible embodiments, the outer annular chamber 20 can comprise two sectors 20' and 20" which are fluidically separated from each other by two passages 27 which are formed on the base 4 in diametrically opposite positions. Preferably, the two passages 27 are mutually aligned along the direction Y. Preferably, the two sectors 20' and 20" are mutually symmetrical.

Advantageously, the passages 27 define corresponding channels for transmitting the flames from the second crown 22 to the third 24 and/or first crown 12 (in the case - not shown - in which the spark plug is positioned in correspondence with the external side wall 25), or vice versa (in the case in which the spark plug 9 is positioned in correspondence with the cylindrical wall 15 or in any case in the internal depressed area 13).

Advantageously, the two diametrically opposed passages 27 facilitate the step of molding the base 4 and, in particular, facilitate the extraction of the base 4 from the mould.

Advantageously, in some possible embodiments, in addition to or instead of the passages 27 obtained on the base 4, holes can be provided - obtained on the external annular lid - for transmitting the flames from the second external crown to the first and/or third crown, or vice versa, depending on the position of the spark plug 45. Conveniently, in some possible embodiments not shown here, a single passage 27 may be provided and, therefore, the outer annular chamber 20 comprises a single and only annular sector which is interrupted only in correspondence with the passage 27.

The outer annular chamber 20 is fluidically connected to the two side cavities 32" and 32"' of the injector holder 6, while the inner chamber 10 is fluidly connected to the central cavity 32' of the injector holder 6.

The two side cavities 32" and 32'" of the injector holder 6 are configured to suck primary air 17 from below the hob 90. Conveniently, the two side cavities 32" and 32'" of the injector holder 6 can be configured to draw primary air 17 exclusively from below the cooking hob 90, or they can be configured for drawing primary air 17 from below the cooking hob 90 and also from above the cooking hob itself. Advantageously, by drawing in air (at least) from underneath the hob, the two side cavities 32" and 32'" of the injector holder 6 do not require large dimensions to increase the power of the burner.

Each lateral concave element 31" and 3T" comprises at least one opening, 50" and 50'" respectively, for the entry into the corresponding lateral cavity 32' and 32" of primary air 17 coming (at least or exclusively) from below the hob 90.

Suitably, each of the two lateral cavities 32" and 32'" is defined within a corresponding lateral concave element 31" and 3T" which comprises a bottom wall and/or a lateral wall which can/can be partially open or can/may be provided with holes to thus allow the entry of primary air 17 into the cavity (also or only) from below the cooking hob 90. Preferably, the back wall and/or the side wall are partially open (i.e. they have some missing areas) to thus allow the entry of primary air 17 into the cavity (also or only) from below the cooking hob 90.

Advantageously, as shown in the figures, each of the two side cavities 32" and 32'" comprises a side wall partially open in one or more areas, preferably in two areas facing each other, to thus allow the entry of primary air 17 inside the cavity from underneath the hob 90.

The central concave element 3T of the injector holder 6 is configured to draw primary air 17 into the central cavity 32' from above the cooking surface 90 and/or from below the cooking surface 90. Conveniently, the element central concave 3T is configured to suck primary air 17 into the central cavity 32' exclusively from above the cooking hob 90, or exclusively from below the hob 90, or again it can be configured to suck inside of the central cavity 32' primary air 17 both from below the cooking surface 90 and from above the cooking surface itself.

Conveniently, in a possible embodiment shown in the figures, the central cavity 32' is defined inside the central concave element 3T which comprises a side wall and a bottom wall which are completely closed, to thus allow the entry of primary air 17 inside the central cavity 32 only from above the cooking surface 90.

Conveniently, base 4 includes:

- a central duct 40', which internally defines a central channel 42' which at the bottom is intended to face the central injector 33' of the injector holder 6 and which opens up - preferably out - into the internal chamber 10,

- two lateral ducts, respectively 40" and 40'", each of which defines within it a corresponding lateral channel 42" and 42'" which is intended to face a respective lateral injector 33" and 33”’ below of the injector holder 6 and which opens at the top - preferably comes out - into the outer annular chamber 20.

Preferably, the central duct 40' extends along the Z direction and, at least in part, extends downwards from the bottom of the base 4.

Preferably, each side duct 40" and 40'" extends along the Z direction and, at least in part, extends downwards from the bottom of the base 4.

Preferably, each of the three ducts 40', 40" and 40'" of the base 4 has a substantially vertical development (i.e. along the Z direction) and is coaxial to a corresponding injector with a vertical axis mounted on the injector holder 6.

Conveniently, in a possible embodiment not shown, the central injector 33' is mounted inclined/angled with respect to the direction Z, and the central duct 40' of the base 4 which faces said central injector is also correspondingly inclined/angled 33'.

Conveniently, in a possible embodiment not shown, the lateral injectors 33" and 33'" are mounted inclined/angled with respect to the Z direction, and the respective lateral ducts 40" and 40' are also correspondingly inclined/angled " of the base 4 which face the corresponding side injectors 33" and 33'".

Conveniently, the two side ducts 40" and 40'" exit inside the outer annular chamber 20 in areas that are different from each other and, preferably, each of the two side ducts 40" and 40"' exits in only one of the two sectors 20' and 20" of the external annular chamber 20. Preferably, the two lateral ducts 40" and 40'" lead into the external annular chamber 20 in respective areas which are diametrically opposite each other and aligned along the direction X.

Advantageously, the duct 40', 40" and/or 40'" can define within it a linear Venturi channel, preferably with a vertical axis.

Advantageously, the central duct 40' and the internal mixing/distribution chamber 10 are configured so as to define a radial Venturi, i.e. so as to cause a radial Venturi effect. Preferably, the side ducts 40" and 40'" and the outer annular mixing/distribution chamber 20 are configured so as to define a corresponding radial Venturi, i.e. so as to cause a radial Venturi effect.

Preferably, the central duct 40' defines within it a central channel 42' which is substantially convergent (in the direction away from the injector).

Preferably, the two side ducts 40" and 40'" define inside them respective side channels 42" and 42" which have (in the direction away from the injector) a first converging section, a second section substantially constant or slightly convergent section, and a third divergent section.

Conveniently, the base 4 and the injector holder 6 are configured in such a way that the support of the base 4 on the injector holder 6 is such that the base itself is spaced from the hob 90 to such an extent as to determine with this the passages for the secondary air intended for the first 12 and/or the third ring of flames 24, i.e. for the flames which emerge inside the internal depressed zone 13 .

Suitably, the injector holder 6 comprises means for fixing it to the hob 90. Preferably, the means for fixing the injector holder 6 to the hob 90 are provided in correspondence with said lateral concave elements 31" and/or 31" ' of the injector holder itself. Advantageously, the two lateral concave elements 31" and/or 31'" of the injector holder 6 are provided with at least two fins 36 which project outwards to adhere to the hob 90 from below. Conveniently, in correspondence with the fins 36 they can two or more through holes 47 (preferably threaded) intended to be passed through by members 48 (for example screws) for fastening the injector holder 6 to the sheet metal of the cooking hob 90. Preferably, the two fins 36 extend radially towards the external by, or in correspondence with, a crown 37 which externally wraps the lateral walls of each concave element 3T, 31" and 31 '".

Advantageously, the through holes 47 are positioned laterally with respect to the gas supply conduit 34 and, in particular, the axes which develop along the Z direction and which cross the section of the through holes 47 do not intersect the supply conduit 34, to avoid so that the workings to obtain said holes can come (even inadvertently) to affect the integrity of the supply duct 34.

Conveniently, the three concave elements 3T, 31" and 31'" are connected to each other at their bottom by a corresponding connecting section 38. Preferably, the supply duct 34 crosses the connecting section 38 which is associated at the bottom of the aforementioned three concave elements.

Conveniently, in a possible embodiment (see fig. 1 C), the bottom of the base 4 and the injector holder 6 are configured in such a way that, following the support of the base on the injector holder 6, a passage is delimited between these to allow the entry into the central cavity 32' of the injector holder 6 of primary air 17 coming also or only from above the hob 90.

Conveniently, the bottom of the base 4 and the injector holder 6 are configured in such a way that, following the resting of the base on the injector holder 6, the lateral cavities 32" and 32" are sealed at the top or in any case in such a way as to prevent significant entry into said cavities 32" and 32" of primary air 17 coming from above the cooking hob 90. Advantageously, the contact between the bottom of the base 4 and the side concave elements 31" and 3T" is also such as to prevent the entry into the side cavities 32" and 32'" of cooking residues, dirt or liquids coming from above the hob which, undesirably, could block the corresponding injectors or come into contact with electronic components contained within the application itself or underneath it (for example an oven).

Preferably, in some possible embodiments not shown here, the bottom of the base 4 can be configured in such a way that, following its resting on the injector holder 6, a passage is delimited between these to allow entry into the lateral cavities 32" and 32'" of the injector holder 6 of primary air 17 also coming from above the hob 90.

Advantageously, the side wall of the central concave element 31' comprises a central support collar 35' for the base 4. Preferably, the central collar 35' extends above the crown 37 which projects outwards from the side walls of the central concave element 31' to thus adhere from below to the sheet metal of the cooking hob 90.

Advantageously, each side concave element 31" and 3T" comprises at the top a corresponding side collar 35" and 35'" for resting and supporting the base 4. Preferably, the side wall of each side concave element 31" and 31 '" is provided with a crown 37 projecting outwards to adhere from below to the sheet metal of the cooking hob 90. Furthermore, said lateral wall extends above the crown 37 defining a corresponding collar 35" and 35' " of support and support of the base 4.

Conveniently, the lateral collars 35" and 35'" of the lateral concave support bodies 31" and 3T" project upwards more than the central collar 35' of the central concave element 3T.

Advantageously, the development along the Y direction of each of the two lateral cavities 32" and 32'" is substantially equal to, or may be slightly greater or even less than, the development along the Y direction of the central cavity 32'.

Advantageously, the development along the X direction of each of the two lateral cavities 32" and 32'" is substantially equal to, or may be slightly greater or even less than, the development along the X direction of the central cavity 32'.

Advantageously, the central concave element 31' - which is fluidly connected to the internal chamber 10 for feeding the first ring of flames 12 - drawing in primary air (also or only) from above the cooking surface 90, is practically insensitive to the phenomenon of the stream and moreover it has dimensions suitable for suitably feeding (i.e. with an air- gas mixture sufficiently rich in primary air) the first crown of flames 12 which has the smallest share (equal to approximately 15 - 25%) of the total power of the burner.

The side concave elements 31" and 3T" of the injector holder 6 are particularly advantageous as they suck in the primary air from below the cooking surface 90 and therefore, even if they are small and compact, they are suitable for suitably feeding (i.e. with a gas-air mixture sufficiently rich in primary air) the second and/or third crown of flames 22 and 24 which have the greatest share (equal to about 75 - 85%) of the total power of the burner

Advantageously, the base 4 comprises lower means for supporting and coupling said base to the injector holder 6.

Furthermore, on the lower surface of the bottom of the base itself, around each side duct 40" and 40"', a corresponding contact profile 43" and 43"' is provided which is configured to abut and rest on the entire upper edge of the collars 35" and 35'" of each side concave element 31" and 3T" of the injector holder 6, thus defining a closure which can be substantially airtight or in any case such as to prevent significant entry of primary air 17 from above the hob 90 inside each lateral cavity 32" and 32" provided in the injector holder 6.

Advantageously, a shaped profile 43' can also be provided around the central duct 40' which is preferably substantially at the same level with respect to the contact profiles 43" and 43'" provided around the lateral ducts 40" and 40". However the fact that the collars 35" and 35'" of the lateral support bodies 31" and 3T" develop upwards more than the central collar 35' of the central concave element 3T causes that there is a contact and a closure between the contact profiles 43" and 43'" which can be substantially airtight or in any case such as to prevent a significant entry of primary air 17 from above the hob 90 inside of the side cavities 32" and 32'" for primary air from above the hob 90, while the shaped profile 43' remains spaced with respect to the central collar 35' so as to define a passage for entry inside of the central cavity 32' for primary air 17 from above the hob 90. Conveniently, in a possible embodiment, the central collar 35' can develop with a height equal to that of the lateral collars 35" and 35" ', thus creating a closure with the shaped profile 43' which can be substantially airtight or in any case such as to prevent a significant entry of primary air 17 from above the hob 90, while the central concave element 3T is provided with openings - equal or similar to those of the lateral concave elements - for the entry into the central cavity 32' of primary air 17 from below the cooking surface 90, thus obtaining a burner 2 which draws in primary air completely and exclusively from below the hob 90,

Furthermore, on the lower surface of the bottom of the base itself, around each duct, a section of shaped profile can be provided which rests wholly or in part on a section of counter-shaped profile provided on each concave element 31', 31" and 31" of the injector holder 6.

Advantageously, the injector holder 6 can comprise a further fin 44 for supporting a spark plug 45. Advantageously, the injector holder 6 can comprise a further fin for supporting a thermocouple (not shown). However it should be pointed out that, according to market requirements, the burner may be provided or may be without a spark plug 45 and/or a thermocouple.

Advantageously, the central concave element 3T is provided with at least two further wings 44 which project outwards. Preferably, as shown in the figures, the further fins 44 are configured to be flush with or protrude above the hob 90, or in any case so as to be visible from above the hob 90 once the injector holder 6 has been attached to the latter. Conveniently, a seat for supporting a spark plug 45 can be obtained in correspondence with a further fin 44. Preferably, the two further fins 44 extend radially outwards from, or in correspondence with, a crown 37 which wraps externally the lateral walls of the central concave element 3T.

The operation of the burner 2 according to the invention is traditional in that the gas, which arrives in the injector holder 6 from the gas inlet 30, passes through the supply duct 34 and exits from each injector 33', 33" and 33"' inside the corresponding cavity 32', 32" and 32'", from where it then enters the respective channel 42', 42" and 42'" of the base 4, dragging the primary air 17 with it ( at least or only) from below the cooking surface 90 for the side cavities 32" and 32'" and sucked in (at least or only) from above the cooking surface 90 for the central cavity 32'.

The flow of gas and primary air 17 begins to mix in the channels 42', 42" and 42'" (in particular in the case where the ducts have an internal passage section which does not define a vertical linear Venturi duct) and it then completes its mixing in the corresponding chamber 10 and 20 into which they flow, or it mixes for the most part or entirely in the channels 42', 42" and 42'" (in particular in the case in which the ducts define inside a vertical linear Venturi channel) to then flow into the corresponding chamber 10 and 20 already completely mixed or in any case mostly mixed.

In particular, the mixture of gas (which comes out of the central injector 33') and primary air 17 (which is entrained inside the central cavity 32') passes through the central channel 42' and then enters the internal chamber 10, to thus feed the first crown of flames 12 which emerges from the first doors 11. Furthermore, the gas mixture (which emerges from the two lateral injectors 33" and 33"') and the primary air 17 (which is entrained to the lateral cavities 32" and 32"') crosses the lateral channels 42" and 42"' and then enters the external annular chamber 20, thus feeding the second ring of flames 22, which comes out of the second doors 21 , and/or the third crown of flames 24, which emerges from the third doors 23.

Conveniently, it is understood that in an embodiment not shown here, the central concave element 31' can be made like the side concave elements 31" and 31'", thus allowing suction inside the central cavity 32 ' of primary air 17 coming (only or also) from below the hob.

The present invention also relates only to the injector holder 6 as described above in its essential and/or preferential features.

From what has been said it is clear that the burner according to the invention, and in particular its injector holder, is somewhat more advantageous than traditional solutions because:

- despite having an elongated development of the injector holder, it allows at the same time to generate a high heating power, in particular in correspondence with the crowns of flames which emerge uniformly and homogeneously from the external annular chamber,

- it is particularly compact, in particular the injector holder - being long and narrow - has a reduced overall width, thus allowing an important saving of space which facilitates its installation in certain applications,

- it is lighter,

- it is particularly economical as it requires the use of a smaller quantity of material and furthermore - being long and narrow - it is possible to increase the number of imprints on the die-casting mould, thus allowing for the creation of a greater number of pieces in a single molding of die casting,

- it is made up of only three pieces and thanks to the creation of the base in a single diecast piece, without recovery operations, it is quite simple and cheap to make,

- has a particularly limited height,

- the assembly of the three components (injector holder, base and lid) is particularly easy, fast and intuitive.

In particular, the burner according to the invention, and in particular its injector holder, is somewhat more advantageous than traditional solutions since it allows to generate a high heating power, while being at the same time more economical and compact than traditional solutions. The present invention has been illustrated and described in some of its preferred embodiments, but it is understood that executive variants can be applied to them in practice, without however departing from the scope of protection of the present patent for industrial invention.