EP4285054A1 - Atmospheric gas burner for cooking appliances - Google Patents

Abstract

Atmospheric gas burner (10; 110) of the partially-aerated type for a cooking appliance, comprising a lower cup (1; 101) and means for constraining it to a top (4; 104) of the cooking appliance, an intermediate body (2; 102) which is constrained to and overlaps said lower cup and which has a central deliver chamber (9b; 109b) for delivering the fuel mixture, that is provided with its own central flame spreader, and at least one perimeter delivery chamber (9a; 9c; 109a; 109c) for delivering the fuel mixture, that surrounds at least partially said central chamber and that is provided with two perimeter flame spreaders, and means (3a; 3b; 103) for the upper covering of said central chamber and of said two perimeter chambers, wherein said central chamber and said two perimeter chamber are fluidically separated from each other, and wherein each of said delivery chambers comprises at least one own mixer (8a; 8b; 8c; 108a; 108b; 108c) with radial Venturi effect supplied by a respective injector (6a; 6b; 6c; 106a; 106b; 106c) housed in said lower cup. Advantageously, said lower cup comprises a respective housing (5a; 5b; 5c; 105a; 105b; 105c) for each of said injectors, each of said housings for said injectors being fluidically separated from each of the other housings, at least when said intermediate body of the burner is constrained to said lower cup.

Description

“ATMOSPHERIC GAS BURNER FOR COOKING APPLIANCES”

FIELD OF THE INVENTION

The present invention concerns an atmospheric gas burner for cooking appliances, for example and preferably adapted for cooking in the domestic environment, of the partially-aerated type, i.e. of the type wherein the fuel mixture, that is delivered by the flame spreader or flame spreaders of the burner, is a fuel mixture generally consisting of a fuel gas, for example methane or LPG, and of a given volume of air (primary) in a non-stoichiometric quantity such as to allow the combustion of the gas, so that it is necessary to add an additional volume of atmospheric air (secondary air) present in the surrounding environment at the flame holes of the flame spreader, or flame spreaders, of the burner in order to allow the combustion of the gas itself.

KNOWN PRIOR ART

In the field of the atmospheric gas burners for cooking appliances of the type set forth above, it is known to implement a particular type of burner comprising a lower cup, that is constrained to the top of the cooking appliance, and an intermediate body, that is removably constrained above of the aforesaid lower cup and that in turn comprises a plurality of delivery chambers for delivering the fuel mixture. The delivery chambers of the intermediate body are provided with respective flame spreaders and are closed on top by appropriate covering means, such as covers for example.

In particular, it is known to implement such delivery chambers of the intermediate body of the burner in a substantially concentric way, for example by placing a central delivery chamber at least partially surrounded by one or more perimeter delivery chambers, and wherein each of them is supplied, through at least one mixer dedicated thereto, for example of the Venturi effect type, with a fuel mixture formed by gas and primary air.

For the purpose of limiting the overall dimensions of the burner and in particular the dimensions in height, burners are known wherein each mixer of every delivery chamber is a mixer of the so-named “radial Venturi effect” type, consisting of a short axial duct which is shaped such as to allow the inflow of a volume of pressurized gas and of an adapted volume of primary air at its lower entrance and that ends in a narrow section, beyond which a disc-shaped chamber, shaped such as the fluids transiting within such mixer (i.e. the fuel gas and the primary air) expand gradually in a radial direction (i.e. substantially perpendicular to the axis of the duct), opens. Whenever, through an appropriate injector, a pressurized fuel gas is injected along the axis of the axial duct, the shape of such mixer allows the generation of a Venturi effect whereby a minimum depression is established at the lower entrance of the axial duct and which, together with the dragging effect due to the flow of pressurized fuel gas, is sufficient to draw a proper quantity of primary air inside the same axial duct, and whereby the proper mixture, mainly inside the aforesaid disc-shaped chamber, of the fuel gas injected with the primary air thus drawn is achieved.

The injectors supplying the fuel gas to the respective mixers with radial Venturi effect of each delivery chamber are housed on the lower cup and can be supplied separately or together.

Although there are burners of the type set forth above, with delivery chambers connected to each other by ducts, there are some implementations of this type of burner in which the delivery chambers can be fluidically separated from each other. For example, the patent WO 2004/044490 Al in the name of the present Applicant describes a similar burner in which the delivery chamber of the central fuel mixture is surrounded by two perimeter delivery chambers fluidically separated from each other and from the central one, and in which a first mixture with radial Venturi effect supplies the central delivery chamber and two distinct mixers with radial Venturi effect supply the perimeter delivery chambers.

The delivery chambers of the fuel mixture are formed on an intermediate body of the burner that is constrained to a respective lower cup, which houses the injectors of the different mixers with radial Venturi effect. The injectors that supply the fuel gas to the mixers with radial Venturi effect described in WO 2004/044490 Al can be adjusted separately or together to one another through appropriate taps.

WO 2004/044490 Al does not describe particular shapes of the respective lower cup and further provides that the burner draws primary air through openings placed above the top of the cooking appliance. The patent application WO 2011/144630 A2, in the name of DEFENDI, describes another burner of the type set forth above that is very similar to the one of WO 2004/044490 Al, although differing from the latter for the fact that the delivery chamber of the fuel mixture, i.e. the central chamber and the two perimeter chambers that surround at least partially the central one, are fluidically connected to each other. In the burner of WO 2011/144630 A2, the merging of the fuel gas flows coming from different mixers with radial Venturi effect can cause an unbalanced delivery of such mixture from the respective flame spreaders.

The Chinese patent CN 104696963 A of MIDEA yet describes another burner very similar to the one described in WO 2004/044490 Al, wherein, however, it is provided that the lower cup constrained to the top of the cooking appliance houses the injectors, intended to emit a flow of gas in the respective mixers with radial Venturi effect, in a single compartment, such as the primary air drawn from such mixers flows to and affects these injectors contemporaneously.

The presence of a single housing compartment of the injectors formed in the lower cup of CN 104696963 A can involve an irregular primary air inflow to the individual mixers of the burner and thus an irregular formation and distribution of the fuel mixture.

The US patent application US 2007/218414 A describes an atmospheric gas burner in which the lower cup supports an intermediate body that defines a central chamber and a perimeter delivery chamber of the fuel mixture fluidically separated from each other. The lower cup of the burner of this patent comprises three housings that are, when the intermediate body is mounted on such cup, fluidically separated and that support three respective injectors intended to supply respectively a mixer with radial Venturi effect placed in the aforesaid central chamber and two mixers with axial Venturi effect, the latter both placed inside the aforesaid perimeter chamber. The delivery chambers each comprise their own flame spreader.

The fact that the two mixers of the axial Venturi effect type supply a same delivery chamber of the fuel mixture in the burner of US 2007/218414 A, involves significantly high volumes and supply flow rates (actually due to the use of mixers with axial, and not radial, Venturi effect for the perimeter delivery chamber) in addition to not protecting such burner, and in particular the perimeter delivery chamber, from the possible irregular distribution of the fuel mixture, due to different thermodynamic and fluid dynamic conditions to which different areas of the burners can be subjected.

The US patent US 2010/279238 A of the same owner of US 2007/218414 A describes a burner quite similar to the one described in this last patent application US 2007/218414 A.

An object of the present invention is to solve or mitigate the technical problems that afflict the known partially-aerated atmospheric gas burners of the type briefly described above, i.e. in summary, those gas burners provided with multiple delivery chambers for delivering the fuel mixture and intended for cooking appliances.

A further object of the present invention is thus to implement a burner of the type set forth above that is particularly efficient in terms of fluid dynamics, thus allowing a regular supply of the fuel mixture to the respective flame spreaders and that is contemporaneously both easy to make and allows optimal combustion steadiness.

BRIEF SUMMARY OF THE INVENTION

These and further objects are achieved by the atmospheric gas burner for cooking appliances according to the first independent claim. Particular embodiments of this burner are further claimed in the respective dependent claims.

According to the present invention, the atmospheric gas burner of the partially- aerated type for a cooking appliance comprises a lower cup and means for constraining it to a top of the cooking appliance, an intermediate body of the burner which is constrained to and overlaps such lower cup and which has a central delivery chamber for delivering the fuel mixture, that is provided with its own central flame spreader, and which has at least two perimeter delivery chambers for delivering the fuel mixture, that surround at least partially said central chamber and that are provided with at least one at least partially-perimeter flame spreader, as well as means for the upper covering of the central chamber and of the two perimeter chambers.

The burner according to the invention provides that the aforesaid central chamber and the at least two perimeter chambers are all fluidically separated from each other and that each of such delivery chambers comprises at least one own mixer with radial Venturi effect supplied by a respective injector housed in the lower cup.

Advantageously, the lower cup comprises a respective housing for each of said injectors, wherein each of such housings for the aforesaid injectors is substantially fluidically separated from each of the other housings, at least when the aforesaid intermediate body of the burner is constrained to the lower cup.

The practically complete fluidic separation of the flow of fuel gas and primary air flowing to the flame spreaders of the delivery chambers of the burner claimed herein, achieved through the fluidic separation not only of such delivery chambers but also of the housings of the injectors of the respective mixers with radial Venturi effect, allows to optimize the fluid dynamic efficiency of the burner, thus making the combustion more regular.

As the skilled person in the art can understand, the very low pressure differences generated by the mixers with radial Venturi effect, in addition to the aforesaid dragging effect due to the injection of a fuel gas flow and thus the fluidic flows by them produced, are easily affected by variations and turbulences of the outer environment, such as the achievement of a high fluid dynamic efficiency, as demonstrated in the burner claimed herein, is not obvious but can lead to a significant improvement of the thermodynamic conditions of the combustion.

The fact that the (at least) two perimeter chambers, for example of a substantially semi-annular shape, and the central chamber are all fluidically separated from each other, and that each of them consequently comprises at least one own mixer with radial Venturi effect, optimizes the fluidic gas and primary air flows, as well as the flow of the fuel mixture achieved by mixing them, and thus improves the fluid dynamic conditions in which the burner operates.

It should be remembered here that the mixers with radial Venturi effect, for example described in FR 1197178 A, are Venturi tubes that have, depending on the axial direction of the fluidic flow passing through them, immediately downstream of a narrow sectional zone, a disc-shaped expansion chamber inside which the fluid expands radially, after having undergone a substantially 90° deviation with respect to its direction of introduction into such Venturi tubes. In the most common mixers with axial Venturi effect, corresponding to the traditional axial Venturi tubes, the fluidic flow, after having passed through a narrow sectional zone, instead expands inside a substantially conical chamber, along substantially axial and gradually divergent directions with respect to its axial direction of introduction into such mixers.

Moreover, since the burner claimed herein can provide not only one single adjusting member for adjusting the injectors of the fuel gas, for example a single tap which contemporaneously controls the inflow of the gas to the injectors but also alternatively the presence of two or more adjusting members for adjusting the injectors, for example a tap for each injector, such as to control the inflow of the gas to the various injectors in a differentiated way and thus the flow rate of the mixture in the single delivery chambers, the solution described herein thus allows to control the distribution of heat on the surface of the burner in a very accurate way.

In a further embodiment of the present invention, the holes of each flame spreader are shaped to horizontally direct the outflowing fuel mixture, for example by prearranging the outflow section of the fuel mixture so that the respective walls are substantially vertical and extend along a substantially horizontal axis, when the intermediate body of the burner is constrained above the aforesaid lower cup.

Such solution, in combination with the solution which provides for each delivery chamber of the fuel mixture to have its own path substantially fluidically separated from the others and with the solution which consists in the use of various mixers with radial Venturi effect, leads to an improvement of the effectiveness of the burner in terms of propagation of the flame and thus of the heat delivered. The substantially horizontal outflow of the fuel mixture from the flame holes of the flame spreaders reduces possible pressure drops to which the flow of the mixture can be subjected and thus leads to an improved evenness of the distribution of the flames on each flame spreader, considering that the use of multiple mixers with radial Venturi effect involves the fact that they do not have high fluidic flow rates - due to the dimensional limitations of the burner -.

Still according to a further aspect of the present invention, as will become clearer to the skilled person in the art, the burner object of this invention can indifferently provide means for allowing a supply of primary air inside the mixers with radial Venturi effect, by both the drawing primary air from above the top of the cooking appliance and alternatively (or hypothetically also simultaneously) by the drawing primary air from under such top of the cooking appliance.

Finally, as will become clearer to the skilled person in the art, the means for covering the delivery chambers of the fuel mixture of the burner claimed herein can be individual for each delivery chamber or made in one piece for covering two or more delivery chambers contemporaneously.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

These and further aspects of the present invention will become clearer to the skilled person in the art in the following description of an embodiment of the present invention provided herein by way of example and without limitations, with reference to the accompanying figures, in which: figure 1 is a perspective view of a burner according to a first embodiment of the invention; figure 2 is a sectional view, according to the line A- A, of the burner of figure 1; figure 3 is a sectional view, according to the line B-B, of the burner of figure 1; figure 4 is a three-dimensional view of the lower cup of figure 1; figure 5 is a three-dimensional view of the flame spreader of the burner of figure 1; figure 6 is a three-dimensional view of the covers of the burner of figure 1; figure 7 is a perspective view of a burner according to a second embodiment of the invention; figure 8 is a sectional view, according to the line A- A, of the burner of figure 7; and figure 9 is a sectional view, according to the line B-B, of the burner of figure

7.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT

INVENTION With initial reference to figure 1, according to a first embodiment of the present invention an atmospheric gas burner 10 for a top of a cooking appliance comprises a lower cup 1 shaped for being fixed to a top 4 of a cooking appliance, an intermediate body 2 of the burner 10, that is provided with delivery chambers and a plurality of flame spreaders and that is shaped for being removably coupled to the lower cup 1, as well as means for the upper covering of the intermediate body 2, which specifically consist of two covers 3 a, 3b.

According to an aspect of the present invention, the lower cup 1 of the burner 10 is made in one piece, as the intermediate body 2 is made in one piece, whereas the covering means, i.e. the two covers 3a, 3b, are made in two distinct pieces. Further modes for implementing the burner can however be provided without thereby departing from the protection scope requested herein.

By examining the burner 10 more in detail with particular reference to figures 2, 3 and 4, it comprises, as stated, a lower cup 1, which preferably consists of a generally concave single body that in turn comprises, in addition to means for constraining it (not shown) to the top 4 of a cooking appliance, a generally horizontal duct 7 provided with a connection to a pipe of an outer gas distribution network (on the right in figure 2) and with three outflow openings that are in turn fluidically connected to three injectors 6a, 6b, 6c which are respectively fixed on the bottom of three housings 5a, 5b, 5c made in such lower cup 1 of the burner 10.

The supply duct 7 for supplying the fuel gas to the injectors 6a, 6b, 6c is functionally connected, according to an aspect of the present invention, to a single tap that contemporaneously adjusts the flow rate of the gas directed to such injectors 6a, 6b, 6c.

It should be observed that, although in the embodiment of the burner 10 depicted herein there is only one supply duct for supplying the fuel gas to the injectors 6a, 6b, 6c, such as a single tap adjusts the flow rate of the gas simultaneously directed to the injectors 6a, 6b, 6c, alternative embodiments of the burner 10 are obviously possible, wherein each injector 6a, 6b, 6c is supplied by its own supply duct for supplying the gas, that is adjusted by a corresponding tap, such as the flow rate of the gas directed to each injector can be adjusted independently of the other flow rates or still wherein there are a first duct, with a respective adjustment tap that adjusts the inflow of the gas to the central injector 6b, and a second duct, with a further respective adjustment tap, that contemporaneously adjusts the inflow of the gas at the two side injectors 6a, 6b, or further combinations of such solutions.

The lower cup 1, in the particular embodiment of the invention considered herein, is shaped such as to define the aforesaid housings 5a, 5b, 5c that are substantially fluidically separated from each other (in particular when the burner 10 is assembled or at least when the intermediate body 2 is coupled to the lower cup 1) and to have primary-air A inflow openings that open, when the lower cup 1 is fixed to such top 4, above the top 4 of the cooking appliance, and that are fluidically connected to such housings 5a, 5b, 5c of the injectors 6a, 6b, 6c.

As the skilled person in the art will understand, such primary-air inflow openings can be made such as to be arranged below the top 4 when the lower cup 1 is fixed to such top 4 or can be arranged partially above and partially below such top 4 of the cooking appliance.

It should be noted that the primary-air inflow openings, obtained thanks to the particular shape of the lower cup 1, are shaped such as there preferably is at least one inflow opening for each of the housings 5a, 5b, 5c of the injectors 6a, 6b, 6c that is distinct from the inflow openings for the other housings. This way, each housing 5a, 5b, 5c of the injectors 6a, 6b, 6c is supplied by its own primary air A flow that is drawn thanks to at least one own primary air opening.

In particular, as seen in figure 4, a safety thermocouple 11 and a spark plug 12, which are adjacent to flame holes of at least one flame spreader of the intermediate body 2 of the burner 10 when the burner 10 is completely assembled, are also arranged on the lower cup 1.

In the embodiment of the burner 10 depicted in figure 1, the thermocouple 11 and the spark plug 12 are arranged in the proximity of the central flame spreader of the intermediate body 2 of the burner 10.

The lower cup 1, also with reference to figure 5, is further shaped such as to be removably coupled on top to the intermediate body 2 of the burner 10, that is in turn shaped such as, when coupled to the lower cup 1, to separate the housings 5a, 5b, 5c of the same lower cup 1 from each other so that they are fluidically separated from each other, with the exception of the afore mentioned primary-air A inflow openings, which obviously fluidically connect all the housings 5a, 5b, 5c to the outer environment above and/or below the top 4 of the cooking appliance.

More in particular, the intermediate body 2 of the burner 10 comprises a central delivery chamber 9b for delivering the fuel mixture and two perimeter delivery chambers 9a, 9c for delivering the mixture that, being of semi-annular shape, surround such central chamber 9b.

Each of the central and perimeter delivery chambers 9b, 9a and 9c of the intermediate body 2, all together herein also defined as “delivery chambers,” is fluidically separated from the other delivery chambers and is provided with its own flame spreader from which the fuel mixture flows out.

It should be noted that the term “flame spreader” herein means a wall that at least partially surrounds a delivery chamber for delivering the fuel mixture and that it is provided with holes, defined as flame holes, adapted to allow the outflow of such fuel mixture for its combustion. In the embodiments of the burner according to the present invention shown herein, such flame holes of the flame spreaders are formed as slits of at least parts of the walls surrounding the respective delivery chamber for delivering the fuel mixture, which slits take the shape of a through hole, i.e. of a flame hole, thanks to the means for covering the intermediate body of the burner itself and which thus define the upper wall of such openings.

Further configurations of such openings, such as perforations, for example formed inside parts of a wall surrounding a delivery chamber for delivering the fuel mixture, are also possible.

As will become clearer hereunder, the holes of the flame spreaders of the burners represented herein are preferably shaped such as to direct the outflowing fuel mixture flow along a substantially horizontal direction.

The central and perimeter delivery chambers 9a, 9b, 9c for delivering the fuel mixture of the intermediate body 2 of the burner 10, when the intermediate body 2 is constrained on top to the lower cup 1, are placed respectively at the housings 5b, 5a and 5c of the lower cup 1 and fluidically communicate with such housings 5b, 5a, 5c thanks to respective mixers with radial Venturi effect 8b, 8a, 8c the intermediate body 2 is provided with, which actually extends respectively inside the aforesaid housings 5b, 5a, 5c.

More in detail, each of the delivery chambers 9a, 9b, 9c for delivering the fuel mixture comprises at least one own mixer with radial Venturi effect 8a, 8b, 8c that is intended to form and supply the fuel mixture, consisting of gas and primary air, to the respective delivery chamber 9a, 9b, 9c and that is in turn supplied by a respective injector 6a, 6b, 6c arranged within its own housing 5a, 5b, 5c of the lower cup 1 and by a primary air flow drawn by the same mixer with radial Venturi effect 8a, 8b, 8c.

It should be reminded that the expression “primary air” means that volume of atmospheric air that is mixed to a fuel gas, such as methane or city gas, in a proportion smaller than the stoichiometric one needed to allow the combustion of the mixture thus obtained. This way, the fuel mixture consisting of gas and primary air requires the addition of a further volume of atmospheric air named “secondary air,” so that it can be combusted. In the burners of cooking appliances, the secondary air generally consists of atmospheric air present in the proximity of the flame holes from which the fuel mixture comes out and from which the combustion flames depart, once such combustion is triggered for example by a spark plug. In the common burners for cooking appliances, both the primary air and the secondary air are not generally supplied through forced flows and do not thus require fan devices for their inflow to the burner.

It should moreover be remembered that a “mixer with radial Venturi effect” is none other than a channel or duct comprising, in succession, a preferably convergent length, a narrow section and a divergent length, wherein the preferably convergent length consists of a cylindrical tube of a preferably decreasing diameter, the narrow section is a length, or a section, of annular duct with constant area that is coaxial to the preferably convergent length, and the divergent length consists of a disc-shaped chamber that extends radially from the narrow section and along surfaces substantially orthogonal to the axis of the preferably convergent length and of the narrow section. When a flow of gas, through an injector, is injected into the preferably convergent length according to a direction coinciding with that of the axis of the same preferably convergent length, the design of this mixer with radial Venturi effect, as known, generates a depression at the inlet section of the preferably convergent length, which draws primary air and also causes, substantially at the radial divergent length where an expansion occurs with the respective recovery of the pressure of the fluids passing through it, the mixing of the primary air with the injected gas.

It is desirable at this point to note that, although a burner 10 comprising an intermediate body 2 defining three delivery chambers 9a, 9b, 9c with respective three mixers with radial Venturi effect 8a, 8b, 8c and a respective lower cup 1 with three housings 5a, 5b, 5c for three injectors 6a, 6b, 6c has been described herein, it should be underlined that also burners with four or more fluidically separated delivery chambers formed on the intermediate body and corresponding four or more housings for the injectors formed on the lower cup, are included in the protection scope requested herein.

Going back to the burner 10 of figures 1 to 6, as the skilled person in the art will have already appreciated, when the intermediate body 2 is constrained on top to the lower cup 1, even removably, three regions that are substantially fluidically separated from each other (with the exception of their fluidic communication with the outer environment for the inflow of primary air) and that consist of the delivery chambers 9a, 9b, 9c of the intermediate body and of the respective housings 5a, 5b, 5c of the lower cup 2, which are reciprocally overlapping, are formed within the burner 10. Such separated regions communicate with the outer environment, above or under the top 4 of the cooking appliance, through respective openings for the entrance of primary air A and each contain an injector 6a, 6b, 6c and a respective mixer 8a, 8b, 8c with radial Venturi effect.

Each of the mixers 8a, 8b, 8c of such separated regions, as seen for example in figures 2, 3 and 5, comprises a lower cylindrical length of axial extent with decreasing diameter, whose inlet section is crossed by the gas injected by the respective injector 6a, 6b, 6c and by the primary air drawn from the same mixer 8a, 8b, 8c by Venturi effect, a narrow section placed at the top of such lower cylindrical length, and then a disc-shaped expansion chamber of radial extent defined below by a flat annular surface 13a, 13b, 13c (figure 5) and above by the corresponding surface, facing such flat annular surface 13a, 13b, 13c, of the covering means consisting of the covers 3a, 3b in the burner 10 shown herein.

The delivery chambers 9a, 9b, 9c of the burner 10, within which the fuel mixture formed in the respective mixers 8a, 8b, 8c is diffused, are respectively provided with flame spreaders extended along at least one of their perimeter walls, and in particular, as far as the perimeter chambers 9a, 9c are concerned, such flame spreaders are preferably extended along the outer perimeter walls, such as to allow the outflow of such fuel mixture towards the outside and the propagation of the flames in substantially circular rings.

Other embodiments wherein the perimeter delivery chambers 9a, 9c for delivering the fuel mixture further comprise a flame spreader along their own inner perimeter wall, are obviously possible.

It should be observed that, between the perimeter delivery chambers 9a, 9c that substantially surround the central delivery chamber 9b, there are channels 16a, 16b that separate such perimeter chambers 9a, 9c and that allow both an inflow of secondary air to the center of the burner 10 and possibly the propagation of the flame from the inside towards the outside of the burner 10, or vice-versa.

It should be noted that the aforesaid separation of the inner space of the burner 10 into three substantially fluidically separated regions consisting of the joining of the delivery chambers 9b, 9c of the intermediate body 2 with the respective housings 5a, 5b, 5c of the lower cup 1 of the burner 10, makes the mixing of the gas with the primary air in the mixers with radial Venturi effect 8a, 8b, 8c more regular and makes the flow of the fuel mixture within the three delivery chambers 9a, 9b, 9c of the same fuel mixture more homogeneous, in addition to preventing possible turbulences, or other adverse thermodynamic or physical conditions related to one of the regions of the burners 10, from affecting the other regions, with a consequent increase of the combustion steadiness.

In particular, such solution, which provides for the making of three substantially fluidically separated regions, allows to calibrate the same injectors 106a, 106b, 106c in an optimal way such as to allow, during the designing step, an accurate balancing of the distribution of the power delivered by the burner, also thanks to the different pressures possibly present in such separated regions.

In fact, such substantially fluidically separated regions of the burner 10 define three respective burners, largely separated from each other.

According to a preferred aspect of the present invention, the flame spreaders of the burner 10 comprise flame holes defined in this specific case as slits 14 and 15 closed on top by the aforesaid covers 3a, 3b of the burner 10, which flame holes are shaped such as to direct the flow of the fuel mixture flowing out of such flame holes along a substantially horizontal direction, i.e. substantially parallel to the bottom of the respective delivery chamber and thus substantially parallel to the cooking top 4.

For example, the outflow section of the fuel mixture of such flame holes defined at least partially by the slits 14, 15 (respectively intended to create real flame holes and pilot flame holes), can be made so that the respective walls are substantially vertical and extend along a substantially horizontal axis, when the intermediate body 2 of the burner 10 is constrained on top to the aforesaid lower cup 1 of the same burner 10.

This design of the flame holes prevents undesired pressure drops from occurring during the delivery of the fuel mixture towards the outer environment and thus contributes to increasing the combustion steadiness, in addition to allowing an optimal arrangement of the flames coming out of the flame spreader.

As already mentioned above, the burner 10 depicted in figures 1 to 6 comprises, as means for the upper closing of the intermediate body 2, two covers 3a, 3b respectively intended for the upper covering of the two perimeter delivery chambers 9a, 9c for delivering the fuel gas of the intermediate body 2 and of the central delivery chamber 9b for delivering the fuel gas of the same intermediate body 2.

This solution allows to make the central delivery chamber 9b for delivering the fuel mixture in a way such as it is extended in height differently from the extent in height of the two perimeter delivery chambers 9a, 9c for delivering the fuel mixture, which perimeter delivery chambers can thus have a smaller or greater height than that of the aforesaid central chamber 9b.

Such possibility is not provided in the atmospheric gas burner 110 depicted in figures 7 to 9 which, otherwise entirely similar to the burner 10 shown in figures 1 to 6, provides that the covering means of the intermediate body 102 consist of a single cover 103 extending substantially planar.

The burner 110, substantially identical to the burner 10 described above, comprises, in addition to the cover 103 and the intermediate body 102, a lower cup 101 comprising three housings 105a, 105b, 105c for respective three injectors 106a, 106b, 106c of the fuel gas and a supply duct 107 for supplying the gas from an outer distribution network to the aforesaid three injectors 106a, 106b, 106c.

The intermediate body 102 comprises three delivery chambers for delivering the fuel mixture 109a, 109b, 109c that are fluidically separated from each other and provided with respective flame spreaders, that each comprise a respective mixer with radial Venturi effect 108a, 108b, 108c and that are intended to be coupled, when the burner 110 is assembled and thus the intermediate cup 102 is constrained on top, even removably, to the lower cup 101, respectively with the housings 105a, 105b, 105c of the same lower cup 101, such as to define regions (chambers) substantially fluidically separated from each other and each provided with at least one primary-air A inflow opening, with at least one injector 106a, 106b, 106c and with at least one respective mixer with radial Venturi effect 108a, 108b, 108c.

This way, each of such regions de facto behaves as a burner separated from the others, although the control of the flow rate of the fuel gas directed to the injectors 106a, 106b and 106c is, in the embodiment depicted herein, achieved by a single tap that determines the flow rate of the gas inside the aforesaid supply duct 107.

It should however be noted that, also in this burner 110, each of the injectors 106a, 106b, 106c of the lower cup 101 can be alternatively supplied by means of a flow of fuel gas adjusted individually by a respective tap, so that the lower cup 101 comprises several supply ducts for supplying the fuel gas to such injectors 106a, 106b, 106c.

In any case, the separation of the burner 110 into three regions that actually constitute three burners substantially fluidically separated from each other allows to calibrate the same injectors 106a, 106b, 106c in an optimal way and thus allows to balance the distribution of the power delivered by the burner in a very accurate way, and in particular the distribution of the maximum thermal power on the bottom of the cooking container placed on such burner, thanks to the fact that the pressures in such regions do not balance each other.

It should further be noted that although the primary-air A inflow openings are implemented inside the burner 110 above the top 104 of the cooking appliance, it is naturally possible to implement such openings, in whole or in part, below such top 104.

Moreover, the housings 105a, 105b, 105c of the lower cup 101 are, when the intermediate body 102 is engaged with such lower cup 101, substantially fluidically isolated from each other, such as the injection of gas and the inflow of primary air A into the respective mixers with radial Venturi effect 108a, 108b, 108c is not affected, or is very little affected, by the physical (thermodynamic) conditions occurring in the other housings of the lower cup 102 of the burner 110.

Similarly, the separation of the delivery chambers 109a, 109b, 109c of the intermediate body 102 prevents possible adverse thermodynamic conditions, that can possibly affect one of the delivery chambers, from having an effect on the other delivery chambers.

Such design of the burner 110, like that of the burner 10, thus increases the combustion steadiness.

The combustion steadiness of the burner 110 is further increased by the design of the flame holes of the flame spreaders the intermediate body 102 is provided with, which flame holes are shaped such as to direct the outflowing fuel mixture along a substantially horizontal axis.

Still, as will become clearer to the skilled person in the art, the fact that the means for covering the intermediate body 102 consist of a single cover 103 of planar extent, although imposing that the heights of the walls of the central and perimeter delivery chambers 109a, 109b, 109c are the same, simplifies the implementation of such covering means with clear savings in terms of production.

Moreover, it should then be observed that in the burner 110, unlike the burner 10 of figures 1-6, the spark plug is placed outside the outer flame ring of the burner, whereas the safety thermocouple is placed at the flame spreader of the central delivery chamber 109b for delivering the fuel mixture, as can be appreciated from the representation of figure 7. This means that the arrangement of the spark plug and the safety thermocouple is linked to design criteria and is not relevant to the protection scope of this patent.

Finally, it should be noted that, although two embodiments of an atmospheric gas burner according to preferred aspects of the present invention are depicted herein with the geometric shapes and configurations schematized in the figures, any other atmospheric gas burner that provides the solution claimed herein, independently of its geometric shape, dimensions and materials used to implement it, falls anyhow in the protection scope defined herein.

Claims

1. Atmospheric gas burner (10; 110) of the partially-aerated type for a cooking appliance, comprising a lower cup (1; 101) and means for constraining it to a top (4; 104) of the cooking appliance, an intermediate body (2; 102) which is constrained to and overlaps said lower cup (1; 101) and which has a central delivery chamber (9b; 109b) for delivering the fuel mixture, that is provided with its own central flame spreader, and at least two perimeter delivery chambers (9a; 9c; 109a; 109c) for delivering the fuel mixture, that surround at least partially said central chamber (9b; 109b), and wherein each of them is provided with at least one perimeter flame spreader, and means (3a, 3b; 103) for the upper covering of said central chamber (9b; 109b) and said at least two perimeter chambers (9a; 9c; 109a; 109c), wherein said at least two perimeter chambers (9a; 9c; 109a; 109b) and said central chamber (9b; 109b) are fluidically separated from each other, and wherein each of said at least two perimeter chambers (9a: 9b: 9c: 109a; 109b, 109c) and said central chamber (9b; 109b) comprises at least one own mixer (8a; 8b; 8c; 108a; 108b; 108c) with radial Venturi effect supplied by a respective injector (6a; 6b; 6c; 106a; 106b; 106c) housed in said lower cup (1; 101), and wherein said lower cup (1; 101) comprises a respective housing (5a; 5b; 5c; 105a; 105b; 105c) for each of said injectors (6a; 6b; 6c; 106a; 106b; 106c), each of said housings (5a; 5b; 5c; 105a; 105b; 105c) for said injectors (6a; 6b; 6c; 106a; 106b; 106c) being fluidically separated from each of the other housings (5a; 5b; 5c; 105a; 105b; 105c), at least when said intermediate body (2; 102) of the burner (10; 110) is constrained to said lower cup (1; 101).

2. Atmospheric gas burner (10; 110) according to claim 1, wherein each of said at least two perimeter delivery chambers (9a; 9c; 109a; 109c) for delivering the fuel mixture has a substantially semi-annular shape.

3. Atmospheric gas burner (10; 110) according to claim 1 or 2, characterized in that the flame holes of each flame spreader are shaped to horizontally direct the outflowing fuel mixture.

4. Atmospheric gas burner (10; 110) according to any one of the preceding claims, wherein each of said mixers (8a; 8b; 8c; 108a; 108b; 108c) with radial Venturi effect comprises a disc-shaped expansion chamber of the fuel mixture, which is at least partially defined above said means (3a, 3b; 103) for the upper covering of said delivery chambers (9a; 9b; 9c; 109a; 109b; 109c) of the intermediate body (2; 102) of the burner.

5. Atmospheric gas burner (10; 110) according to any one of the preceding claims, comprising means for supplying primary air (A) into said mixers (8a; 8b; 8c; 108a; 108b; 108c) with radial Venturi effect, said means for supplying primary air comprising primary-air inflow openings which are placed above said top (4; 104) of the cooking appliance or alternatively below said top (4; 104) of the cooking appliance.

6. Atmospheric gas burner (10; 110) according to any one of the preceding claims, wherein said means for the upper covering comprise a separate cover (3a, 3b) for at least two of said delivery chamber (9a; 9b; 9c; 109a; 109b; 109c) for delivering the fuel mixture.

7. Atmospheric gas burner (10; 110) according to any one of claims 1 to 6, wherein said means for the upper covering comprise a cover (103) made in one piece for covering said delivery chambers (9a; 9b; 9c; 109a; 109b; 109c) for delivering the fuel mixture.

8. Atmospheric gas burner (10; 110) according to any of the preceding claims, wherein at least one of said at least two perimeter delivery chambers (9a; 9c; 109a; 109c) comprises at least one flame spreader with flame holes facing outside the burner or comprises two flame spreaders, one facing said central delivery chamber, the other facing outside the burner.

9. Atmospheric gas burner (10; 110) according to any one of the preceding claims, wherein the flow rate of fuel gas inside said injectors (6a; 6b; 6c; 106a; 106b; 106c) housed in the lower cup (1; 101) are adjusted by a single gas tap or alternatively by two or more separate gas taps.