WO2012035404A1

WO2012035404A1 - Gas burner provided with flame propagation channels

Info

Publication number: WO2012035404A1
Application number: PCT/IB2011/002127
Authority: WO
Inventors: Angelo Bettinzoli
Original assignee: Sabaf S.P.A.
Priority date: 2010-09-13
Filing date: 2011-09-13
Publication date: 2012-03-22
Also published as: IT1401700B1; CN102401376A; ITMI20101662A1

Abstract

An atmospheric burner for gas cookers comprising two or more substantially concentric flame- spreaders (2, 3), separated from each other by at least one projecting body of the burner, in which each flame- spreader is equipped with a plurality of outlet openings (15, 15 " ) to feed a plurality of flames with a gas/primary air fuel mixture. The burner also comprises at least one flame propagation channel (10) obtained in the projecting body between said at least two flame- spreaders and it is characterized in that the flame propagation channel (s) with which it is equipped include at least a diverging or converging portion.

Description

"GAS BURNER PROVIDED WITH FLAME PROPAGATION CHANNELS"

* * *

FIELD OF THE INVENTION

The present invention relates to a gas burner, preferably for domestic use, of the type comprising at least two flame-spreaders separated from each other by at least one body projecting from the burner, for example, consisting of a distribution chamber for the fuel mixture, as well as one o more channels made in the projecting body for propagation of the flame between these flame-spreaders.

It should be noted that here and in the following, the term "flame- spreader" is intended as a generally, but not exclusively, annular element that has at least openings, or cuts, holes, etc. on part of its external wall that enable the discharge of the fuel mixture into the outside environment for its ignition and combustion.

BACKGROUND ART

Usually, this element (i.e. the flame-spreader) is associated with a distribution chamber for the burner's gas/primary air fuel mixture, in order to form the so-called flame crown (ring of flames) of the burner. According to the known art, a flame-spreader can be made as a separate part or instead can be made integrally with the body of the burner.

It should also be noted that here and in the following, the term "flame propagation channel" is intended as a channel that, once the fuel mixture discharged from one flame-spreader has been ignited, allows the transfer of the flame to the mixture exiting the other flame- spreaders fitted to the burner, thereby inducing its ignition.

Burners are known of the type that are fitted with multiple concentric flame-spreaders, generally two flame-spreaders, provided with one or more flame propagation channels from one flame-spreader to another.

WO2006/046922 describes a gas burner comprising a substantially annular chamber for distribution of the fuel mixture associated with an inner flame-spreader and an outer flame-spreader, respectively provided with fuel mixture outlet openings.

The burner is provided with an ignition plug and a thermocouple that, when the burner is mounted on the hob for being used, are inside the perimeter defined by the burner's annular chamber, close to at least one opening for letting out the fuel mixture for the inner flame- spreader.

When the user decides to light the burner, the ignition plug permits ignition of the fuel mixture that comes out from the openings of the inner flame-spreader.

As stated, the outer flame-spreader is not associated with an ignition plug, or similar means, and the fuel mixture coming out of the openings with which it is equipped is lit by means of three channels that permit connection between the inner flame-spreader - lit by means of an ignition plug- or an equivalent means of ignition - and the outer flame-spreader.

In other words, once the fuel mixture coming out of the inner flame- spreader is alight, the propagation ducts enable the flame to be passed to the outer flame-spreader, which is then lit.

According to WO2006/046922, the propagation channels that equip the burner are obtained inside the annular chamber for distribution of the fuel mixture associated with the inner and outer flame-spreaders and are delimited at the top by the cover placed over the annular chamber.

Burners of the type just described have some drawbacks regarding the flame transmission from the flame crown on the flame-spreader associated with means of ignition, to the fuel mixture coming out of the flame-spreader not associated with these means of ignition and separated from the aforesaid flame crown by the annular distribution chamber.

In particular, the applicant has been able to verify that the flame transmission channels of burners in the known art do not allow the flame to be effectively "transferred" through the propagation channels, with the consequent possibility of problems arising in the correct lighting of the flame-spreaders that are not equipped with an ignition plug, or similar associated means of ignition.

In fact, in the propagation channels currently used, having constant cross-sections (i.e. having a constant section along the planes transversal to the direction of flow of the fluid inside the channel), the flame, or rather a partial flow of already burning fuel mixture, might not be conveyed effectively inside the channel for its transfer to another flame-spreader not equipped with means of ignition.

Obviously, if the flame is not transferred, one or more flame crowns will not be lit, with consequent problems of the partial leakage of unburnt fuel mixture and inadequate thermal power generated by the burner. In this case, the user is obliged to turn the burner off and make one or more attempts to light it again.

The object of the present invention is to overcome the above- described problems of the burners currently available and, in particular, to make available a burner equipped with at least two mutually separate flame-spreaders in which the flame propagation between them takes place in an effective manner.

SUMMARY OF THE INVENTION

This and other objects are achieved by a gas burner in accordance with the first independent claim and the subsequent dependent claims.

The atmospheric burner for gas cookers, according to the present invention, comprises two or more substantially concentric flame- spreaders, separated from each other by at least one projecting body of the burner, in which each flame-spreader is equipped with a plurality of outlet openings to feed a plurality of flames with a gas/primary air fuel mixture.

The burner also comprises at least one flame propagation channel obtained in the projecting body between said at least two flame- spreaders and it is characterized in that the flame propagation channel(s) with which it is equipped include at least a diverging or converging portion.

It should be noted that this particular shape of the flame propagation channels between the burner's flame-spreaders induces variations in the pressure and speed conditions of the burning mixture passing within these channels, enabling the flame to be transferred between these flame-spreaders in a particularly effective manner.

More in detail, thanks to the fact that each channel does not have a constant cross-section, and therefore has at least one diverging or converging portion, the flame of the lit flame-spreader can be effectively "drawn" inside each channel for transfer to the other flame-spreaders of the burner.

In particular, the channels that equip the burner according to the present invention enable a Venturi effect to be generated inside them that amplifies and stabilizes the effect of "drawing" the flame inside the channels, permitting effective transfer of the flame between the flame-spreaders.

The applicant has been able to verify that the channels that equip the burner according to the present invention enable effective transfer of the flame, even in conditions of use with the burner at its minimum flow rate.

In addition, the burner according to the present invention comprises at least one ignition plug, or an equivalent means of ignition, which is functionally associated to one of the at least two flame-spreaders, while at least one of the flame-spreaders is without this ignition plug, or similar means.

The ignition plug ignites the mixture of the flame-spreader to which it is associated, whilst the fuel mixture coming out of the other flame- spreaders, which are without ignition plugs, is lit by means of the flame propagation channels, which transfer the flame from one flame- spreader to the other.

According to one possible embodiment of the present invention, the flame propagation channel (s) between the flame-spreaders is/are provided with at least one diverging portion, the end with the largest section of said at least one diverging portion being placed next to or facing said at least one flame-spreader without an ignition plug.

In this way, it is possible to transfer the flame from one flame-spreader to another in an effective manner by means of the "drawing" effect inside the channel or channels, an effect obtained thanks to the special shape of the cross-section of this/these flame propagation channel (s).

Obviously, the burner according to the present invention permits a reduction in the number of means of ignition, such as spark plugs for the flame-spreaders, while at the same time permitting the effective and complete lighting of the burner.

It should be noted that the diverging or converging portion that is provided for each flame propagation channel of the burner can be defined, for example, by inclining the walls of the channel. According to a preferred embodiment of this invention, the projecting body for separating the flame-spreaders of the burner from each other is a distribution chamber for the gas/primary air fuel mixture and the flame propagation channel(s) is/are obtained in this distribution chamber.

As is known, the distribution chambers of gas burners are usually delimited at the top by a cover and, in this case, the propagation channels can be formed by concave channels obtained in the distribution chamber that are closed at the top by the burner cover. The flame propagation channels can also divide the fuel mixture distribution chamber into at least two parts.

In accordance with a further possible embodiment, the burner comprises at least one central mixture distribution chamber associated with at least one central flame-spreader and at least one annular fuel mixture distribution chamber associated with at least one outer flame- spreader, and the annular chamber, in which the flame propagation channel (s) is/are obtained, is externally concentric to the central chamber.

According to the embodiment just described, an ignition plug is functionally associated with the outer flame-spreader of the annular fuel mixture distribution chamber. The central flame-spreader is lit by means of the flame propagation channels, thereby allowing a reduction in the number of ignition plugs, or means of ignition, necessary for the complete lighting of the burner.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the burner according to the present invention shall now be described, purely by way of non-limitative example and with reference to the attached figures, where:

Figure 1 is a plan view of the burner according to the present invention,

Figure 2 is a cross-section view on the E-E plane of the burner in Figure 1 , and

Figure 3 is a cross-section view on the F-F plane of the burner in Figure 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The atmospheric burner for gas cookers, according to the present invention, is equipped with a main body 1 on which at least two flame-spreaders 2 and 3 are obtained that are mutually separated by at least one projecting body of said burner.

As can be seen in the attached figures, the flame-spreaders 2 and 3 are substantially concentric and, according to a preferred embodiment, the projecting body is a distribution chamber for the gas/primary air fuel mixture.

More in detail, the burner shown here, according to a particular aspect of the present invention, is equipped with a central distribution chamber 4 to which flame-spreader 2 is associated and a peripheral annular distribution chamber 5 for the fuel mixture associated with flame-spreader 3.

In other words, the burner according to the present invention preferably comprises two flame-spreaders 2 and 3, the first of which is arranged in a central position, while the other is placed in a peripheral position, so as to define two concentric flame crowns.

It should be noted that each distribution chamber 4 and 5 is defined, at least in part, by the flame-spreader, the body of the burner and a cover (not shown in the attached figures), of a complementary shape to thqt of the upper surfaces of the relative flame-spreaders 2 and 3. In turn, the flame-spreaders 2 and 3 comprise a plurality of openings 15 and 15' for feeding a pluralify of flames wifh a gas/primary air fuel mixture, these flames forming, as is known, fhe flame crowns. The fuel mixture discharge openings 15 of fhe outer flame-spreader 3 are obtained via a plurality of through cuts, preferably radial, which cross through the flame-spreader 3. Instead, the openings 15' of the central flame-spreader 2 comprise a plurality of through holes that cross through the flame-spreader 2.

Obviously, other types and/or forms of openings for discharging the fuel mixture, known in the art, can be used wifh the burner according to fhe present invention without departing from the scope of protection applied for herein.

Furthermore, as is known in the art, the flame-spreaders 2 and 3 can be obtained from a separate element that is subsequently mounted on the body of the burner, or that can be made integral with the latter.

It should also be noted that, even if not explicitly described, nor depicted in the attached figures, a further flame-spreader can be obtained internally next to the outer annular chamber 5, so as to provide a plurality of fuel mixture outlet openings for creating a further flame crown arranged on fhe inner side wall of the annular chamber 5, inside the burner, in a position facing fhe central flame-spreader 2. The burner described here is also equipped, as is known, with at least one Venturi-effect mixing chamber 30, in which the gas/primary air fuel mixture is formed and which feeds fhe fuel mixture distribution chamber(s).

In the embodiment shown in the attached figures, the burner comprises a Venturi-effect mixing chamber of a substantially axial type, which feeds the central distribution chamber 4.

One or more ducts, preferably four radial ducts 9, enable the fluidic connection of the central distribution chamber 4 with the annular distribution chamber 5, such that the gas/primary air mixture formed can also reach the peripheral flame-spreader 3, associated with the annular chamber 5.

Obviously, even if the burner shown herein comprises only one Venturi- effect mixing chamber, it can actually be equipped with two or more Venturi-effect mixing chambers for the separate and/or joint feeding of the distribution chambers 4 and 5 and the associated flame- spreaders 2 and 3.

It should also be noted that the burner according to the present invention could be equipped with any known type of Venturi effect mixer, including radial types.

The burner according to the present invention also comprises one or more channels 10 for flame propagation between the flame- spreaders 2 and 3.

In particular, these flame propagation channels 10 are obtained in the projecting body, or in this case, in the outer annular distribution chamber 5, between the two flame-spreaders 2 and 3, and, as described in detail in the following, are equipped with at least one diverging or converging portion.

As shall become clear in the course of the description, the special shape of the flame propagation channels, and in particular the presence of cross-sections that vary so as to form at least one diverging and/or converging portion, allow the flame to "be drawn" effectively inside them, thereby improving its transfer from one flame- spreader to another.

In particular, as shall be seen in the following, the converging - segment of reduced section - diverging shape of these channels 10 or, alternatively, the simplified shape constituted by a segment of reduced section followed by a diverging segment shown herein, can advantageously induce a Venturi effect, which generates a depression downstream of the reduced-section zone, that is able to effectively draw in the burning mixture, i.e. the flame, situated close to these channels 10.

The flame propagation channels 10 thus enable the flame to be transferred from one flame-spreader to the other in an efficacious manner, preferably during the ignition transient.

When a flame-spreader is lit by conventional means of ignition known for this use, (for example, an ignition plug), the flame is transferred to another flame-spreader of the burner that is not equipped with associated means of ignition.

In fact, the burner according to the present invention comprises at least one ignition plug, not shown n the attached figures, which is functionally associated with one of the two flame-spreaders, whilst the other flame-spreader is without this ignition plug, or known similar means for this use.

According to a preferred embodiment shown in the figures, the ignition plug is associated with the outer flame-spreader 3 of the annular chamber 5 and is placed next to or nearby to at least a portion of a discharge opening 15 of the flame-spreader 3.

According to the known art, ignition of the fuel mixture leaving the opening placed close to the ignition plug allows the fuel mixture leaving the other openings of the flame-spreader to be ignited during the burner's ignition transient.

As stated, the central flame-spreader 2 is not equipped with an ignition plug, or similar means, able to ignite the fuel mixture leaving the openings of said flame-spreader.

The burner, as depicted in the attached figures, is preferably equipped with four channels 10 for propagating, at least partially, the flame obtained in the annular distribution chamber 5.

More in detail, in the embodiment shown herein, each channel 10 comprises a concave channel obtained in the annular mixture distribution chamber 5, destined to be covered, on its upper opening, by the burner cover. It follows that the flame propagation channel 10 is defined in part by the annular distribution chamber 5 and by the cover mounted over it (not shown in the figures), so as to assume a substantially tubular configuration.

Obviously, the propagation channels 10 can be made in alternative ways with respect to that described above, for example, with the ducts that pass through the mixture distribution chamber, or above or below it, etc., without however departing from the scope of protection applied for herein.

The flame propagation channels 10, according to a particular aspect of the present invention, can also subdivide the distribution chamber 5 into a number of parts and, preferentially, the four channels are arranged radially and evenly spaced out between each other so as to subdivide the distribution chamber into four annular distribution chambers of equal size (please see Figure 1 ).

It should be noted that, although having made reference to the embodiment provided with a central flame-spreader 2 associated with a central mixture distribution chamber 4 and an outer flame- spreader 3 associated with an annular distribution chamber 5, the propagation channels 10 can be used with any type of burner equipped with any number of flame-spreaders in which it is necessary to transfer the flame from one flame-spreader to another to allow the correct and complete; lighting of the burner with just one, or a reduced number, of ignition plugs. As stated, the section of the channel is not constant (with respect to the direction of flow of the fluid inside it) and is preferably shaped to form a diverging portion, the end with the largest section of which is positioned next to or facing the flame-spreader without an ignition plug.

As can be seen in the plan view in Figure 1 , the larger end of the diverging portion of each flame propagation channel is thus facing the central flame-spreader 2, which is without an ignition plug.

In doing so, when the user intends to light the burner and the ignition plug ignites the fuel mixture leaving the openings 15 of the outer flame-spreader 3, the flame is drawn inside the propagation channels

10 and transferred to the central flame-spreader 2 so that the fuel mixture leaving the openings 15' can also be lit.

Advantageously, the special shape of the propagation channels and, in particular, the presence of at least one diverging or converging portion allows the flame to be effectively "drawn in" for its transfer to the flame-spreader without means of ignition.

Preferably, a Venturi effect is generated inside the propagation channels that amplifies and stabilizes the effect of drawing the flame inside the channel for its transfer to another flame-spreader.

It should be noted that it is possible to create each propagation channel in a manner such that it includes at least a converging portion followed by at least one portion diverging in the direction of the passage of fluid inside the channel, with the largest end of the diverging portion placed next to or facing the flame-spreader to which the flame must be transferred.

Obviously, the diverging or converging portion of the flame propagation channel with which the burner according to the present invention is equipped: can be made in various ways. In the embodiment shown in the figures, the propagation channels 10 are equipped with inclined radial walls that cause the variation in cross- section of the channel, forming at least one diverging portion.

Claims

1 . An atmospheric burner for gas cookers of the type comprising at least two flame-spreaders (2, 3) substantially concentric and separated from each other by at least one projecting body of said burner, said at least two flame-spreaders comprising at least a plurality of outlet openings ( 15, 15') for feeding a plurality of flames with a gas/primary air fuel mixture, and at least one flame propagation channel ( 10) made in said at least one projecting body between said at least two flame-spreaders (2, 3), characterized in that said at least one flame propagation channel ( 10) comprises at least one diverging or converging portion.

2. The burner according to claim 1 , characterized in that said at least one propagation channel (10) generates a Venturi effect.

3. The burner according to claim 1 or 2, characterized in that it comprises at least one ignition plug, or other means of ignition, functionally associated with one of said at least two flame- spreaders (2, 3), at least one of said flame-spreaders (2, 3) being without said at least one ignition plug, or other means of ignition.

4. The burner according to any of the previous claims, wherein said at least one flame propagation channel (10) between said at least two flame-spreaders (2, 3) is equipped with at least one diverging portion.

5. The burner according to claims 3 and 4, wherein the end with the largest section of said at least one diverging portion is placed next to, or facing, said at least one flame-spreader (2, 3) without said at least one ignition plug, or other means of ignition.

6. The burner according to any of the previous claims, characterized in that said at least one projecting body is a gas/primary air fuel mixture distribution chamber (4, 5).

7. The burner according to claim 6, wherein said distribution chamber (4, 5) comprises an upper cover, characterized in that said at least one flame propagation channel (10) comprises a concave channel made in said distribution chamber (4, 5), said channel being closed at the top by the cover of said at least one distribution chamber.

8. The burner according to either of claims 6 or 7, characterized in that said at least one flame propagation channel (10) subdivides said fuel mixture distribution chamber (4, 5) into at least two parts.

9. The burner according to any of the previous claims, comprising at least one central mixture distribution chamber (4) associated with at least one central flame-spreader (2) and at least one annular fuel mixture distribution chamber (5) associated with at least one outer flame-spreader (3), said at least one annular chamber (5) being externally concentric with said at least one central chamber (4), characterized in that said at least one flame propagation channel (10) is obtained in said at least one annular distribution chamber (5).

10. The burner according to any of the previous claims, of the type comprising at least one annular fuel mixture distribution chamber (5) associated with an outer flame-spreader (3) and with an inner flame-spreader, characterized in that said at least one flame propagation channel is obtained in said at least one annular distribution chamber.

1 1. The burner according to claim 9 and/or 10, characterized in that it comprises _;an ignition plug functionally associated with said outer flame-spreader (3) of said at least one annular fuel mixture distribution chamber (5).

12. The burner according to any of the previous claims, characterized in that it comprises at least four flame propagation channels (10).

13. The burner according to any of the previous claims, wherein said at least two flame-spreaders (2, 3) and said at least one projecting body of separation have a circular development and said at least one flame propagation channel (10) has a radial development.

1 . The burner according to claim 13, characterized in that said at least one diverging or converging portion of said at least one flame propagation channel (10) is at least defined by inclined radial walls.