Abstract:
Gas burner ( 1 ) comprising a mixing chamber ( 5 ); a burner head ( 19 ) provided with a plurality of openings ( 22 ) in fluidic communication with the outside, the burner head ( 19 ) constituting part of the wall of the mixing chamber ( 5 ), the burner head ( 19 ) comprises: a central hole ( 18 ); a first zone ( 23 ) comprising openings of a dimension of between 0.8 and 1 mm; a second zone ( 25 ) surrounding the first zone ( 23 ) and comprising openings of a dimension of between 0.8 and 1.5 mm; a solid annular intermediate zone ( 31 ) situated between the first and the second zone ( 25 ); the burner head further comprising an annular shoulder ( 21 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a gas burner for a grill or kitchen recipient and a portable stove comprising the gas burner. 
       BACKGROUND 
       [0002]    According to the state of the technique, the burner comprises a mixing chamber and a mixer. A flow of a gas/air mixture is injected into the chamber by means of the mixer. 
         [0003]    The flow of the gas/air mixture exits the chamber at a burner head. The burner head constitutes a part of the wall of the chamber. A plurality of openings comprised in the burner head partitions the flow into a plurality of streams. 
         [0004]    A lighting device, provides sufficient energy for initiating a combustion of the gas/air mixture outside the chamber at the openings of the burner head. A continuous flow of gas/air mixture allows stabilizing the flame. 
         [0005]    The speed of the flow must be enough for the flame not to penetrate into the mixing chamber. In fact, if the flow speed is lower than the speed of flammability, the flame rides up the flow. The combustion must be as complete as possible in order to limit the formation of incomplete combustion products, in particular carbon monoxide. 
         [0006]    However, the length of the flame requires that the positioning of the cooking recipient should be at a distance of the order of 20 mm from the burner head. The distance is necessary for ensuring a combustion reaction producing minimum carbon monoxide. However, the cooking recipient does not entirely recover the heat produced by combustion, part of the heat being dissipated into the outside environment. 
         [0007]    In addition, the distance of the order of 20 mm between the burner head and the cooking recipient offers a windage. 
         [0008]    A device for protecting against the wind or a wind break is often required in order to limit the effect of wind gusts. Portable stoves without wind breaks are inoperative from a wind speed of the order of 3 m/s. 
       BRIEF SUMMARY 
       [0009]    The purpose of the present invention aims is to resolve all or part of the aforementioned drawbacks. 
         [0010]    To this end, the present invention relates to a gas burner comprising:
       a mixing chamber,   a burner head provided with a plurality of openings in fluid communication with the outside, the burner head constituting part of the wall of the mixing chamber,       
 
         [0013]    the gas burner being characterized in that the burner head includes:
       a central hole,   a first area with a width between 2 and 20 mm, comprising openings the dimension of which is between 0.3 and 2 mm, the distance separating the openings is between 0.5 and 3.5 mm,   a second area with a width between 2 and 20 mm, the second area surrounding the first area and comprising openings the dimension of which is between 0.3 and 2 mm, the distance separating the openings is between 0.5 and 3.5 mm,   a solid intermediate annular area, located between the first and second area, with a width between 2 and 20 mm,       
 
         [0018]    the burner head further comprising an annular shoulder. 
         [0019]    The flames generated at the burner head create a suction phenomenon. Thus, secondary air, coming from the outside, is made to move from the central hole towards the burner head. The secondary air participates in the combustion reaction and limits the production of carbon monoxide. 
         [0020]    The spatial distribution of the openings and shape of the burner head generate flames of limited length. Thus a cooking recipient may be positioned at a minimum distance in the range of 10 to 15 mm from the burner head without modifying the combustion reaction as the presence of the central hole and intermediate area allow sufficient flame oxygenation. 
         [0021]    The small distance between the cooking recipient and the burner head limits heat leakage. Thus the quantity of heat recovered by the cooking recipient is optimized with respect to the quantity of consumed gas. 
         [0022]    The small distance between the cooking recipient and the burner head also ensures that the wind does not blow out the flame. 
         [0023]    According to an aspect of the invention, the first and/or second area comprise(s) openings the dimensions of which range between 0.8 and 1.5 mm, the distance separating the openings ranging between 1.5 and 2.5 mm. 
         [0024]    It is worth noting that the size of the openings and the distance separating the openings may be different between the first area and the second area. 
         [0025]    According to an aspect of the invention, the first area has a width ranging between 3 and 15 mm. 
         [0026]    According to an aspect of the invention, the second area has a width ranging between 5 and 15 mm. 
         [0027]    According to an aspect of the invention, the intermediate area has a width ranging between 5 and 15 mm. 
         [0028]    According to an aspect of the invention, at least a part of the openings has an axis oriented according to an angle ranging between 0 and 10° with respect to an axis of the central hole. 
         [0029]    According to an aspect of the invention at least a part of the openings of the second area is disposed on an upper surface of the shoulder. 
         [0030]    According to an aspect of the invention, at least a part of the openings of the second area is disposed on an internal surface of the shoulder. 
         [0031]    The annular shoulder of the burner head has a protective role against the wind with regard to the flames generated by the openings located in the first area. 
         [0032]    According to an aspect of the invention, the periphery of the burner head has a peripheral wall forming a crown the edge of which is disposed beyond the surface of the shoulder in an extension direction of the flame. 
         [0033]    The crown protects the base of the flames from the wind. The risk of extinguishing the flames by blowing is thereby reduced. 
         [0034]    According to an aspect of the invention, the crown comprises a radial surface having openings the dimension of which ranges between 1 and 2.5 mm, the openings being in fluid communication with the outside. 
         [0035]    According to an aspect of the invention, the burner comprises a flange surrounding the radial surface of the crown. The distance separating the flange from the radial surface ranges between 0.5 and 2 mm. 
         [0036]    According to an aspect of the invention, the space located between the flange and the radial surface is an annular peripheral chamber. The annular peripheral chamber is in fluid communication with the outside through an annular slit. The annular slit adjoins the edge of the crown. 
         [0037]    According to an aspect of the invention, the flange comprises an upper rim. The upper rim defines the outer peripheral end of the slit. The rim is slanted in the direction of the edge of the crown in such a manner as to partially close the peripheral chamber. 
         [0038]    According to an aspect of the invention the width of the slit ranges between 0.7 and 1.3 mm. 
         [0039]    Part of the flow of the gas/air mixture exits the mixing chamber by the openings of the peripheral surface, transits by the peripheral chamber and reaches the outside by the annular slit. 
         [0040]    The part of the flow of the mixture ignites at the slit, causing a peripheral flame. The peripheral flame protects the flames generated at the burner head from the wind. 
         [0041]    According to an aspect of the invention, the gas burner includes three secured parts:
       a lower part of a mixer and the mixing chamber (A),       
 
         [0043]    The mixer including a tubular duct having an inlet and an outlet delimiting an area for the circulation of a flow of gas/air mixture; a Venturi effect structure is comprised in the circulation area in such a manner as to increase the speed of the flow,
       an upper part of the mixer and the mixing chamber (B),   the burner head (C).       
 
         [0046]    According to an aspect of the invention pertaining to a first embodiment, the three secured parts (A), (B) and (C) are made of deep drawn steel sheet, the burner head (C) being also punched; the three parts (A), (B) and (C) being crimped and/or welded. 
         [0047]    According to an aspect of the invention the flange is comprised in the upper part of the mixer and mixing chamber (B). 
         [0048]    According to an aspect of the invention, the mixer tangentially opens into the mixing chamber. 
         [0049]    The mixer opens onto a tangent of the mixing chamber. The flow of the gas/air mixture is distributed homogenously in the mixing chamber. Thus, the openings of the burner head are equally supplied with gas/air. 
         [0050]    According to an aspect of the invention, the mixer is tangentially connected in the mixing chamber, the tubular duct of the mixer extending inside the mixing chamber. 
         [0051]    The tangential connection of the mixer in the mixing chamber maintains the flow of gas/air mixture at sufficient speed while limiting the head losses at the connection. 
         [0052]    The extension of the tubular duct of the mixer inside the mixing chamber guides the flow in order to obtain a homogenous distribution of the gas/air mixture in the chamber. 
         [0053]    According to an aspect of the invention, a portable stove includes at least a gas burner of the type in which a cup, having a central opening surrounds the burner head. The cup includes a shoulder at the periphery of the burner head and an elevated edge with respect to the burner head around the shoulder. 
         [0054]    The shoulder has a hollow shape and collects projections coming from the cooking recipient or the outside. This disposition facilitates cleaning the portable stove. The elevated edge around the shoulder is an additional protection against the wind by limiting blowing risks. 
         [0055]    According to an aspect of the invention, the cup includes means for fixing to the portable stove alternatively allowing to secure it and detach it. 
         [0056]    The fact that the cup is dismantleable also facilitates cleaning the burner. 
         [0057]    According to an aspect of the invention the portable stove includes, a support for a cooking recipient intended for supporting a cooking recipient, the support including fins surrounding the burner. 
         [0058]    The fins are:
       convex shaped facing the burner head and concave facing the outside,   separated by openings.       
 
         [0061]    The openings and the convex shape of the fins facing the burner head facilitate the discharge of smoke produced by the combustion of the gas/air mixture. The concave shape of the external face of the fins protects the burner head from the wind. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0062]    Anyway, the invention will be better understood with the following description with reference to the accompanying schematic drawings representing, by way of non limiting example, an embodiment example of this gas burner. 
           [0063]      FIG. 1  is a perspective view of a gas burner. 
           [0064]      FIG. 2  is a perspective view of a lower part (A) and an upper part (B) of a mixer and a mixing chamber of the gas burner, according to a first embodiment. 
           [0065]      FIG. 3  is a perspective view of a lower part (A) and an upper part (B) of a mixer and a mixing chamber of the gas burner, according to a second embodiment. 
           [0066]      FIG. 4  is a perspective view of a cooking recipient and a gas burner in operation. 
           [0067]      FIG. 5  is a perspective view of a portable stove comprising the gas burner and a cup. 
           [0068]      FIG. 6  is a perspective view of a portable stove comprising the gas burner, the cup and a support for a cooking recipient. 
           [0069]      FIG. 7  is a longitudinal sectional view of the burner. 
           [0070]      FIG. 8  is a detail of the sectional view of the burner. 
       
    
    
     DETAILED DESCRIPTION 
       [0071]    According to an embodiment, a gas burner  1  includes a mixer  3  and a mixing chamber  5 . The mixer  3  includes a tubular duct  7  provided with a circulation area  9  between an inlet  11  and an outlet  15 . A Venturi effect structure  16  is disposed in the circulation area  9 . 
         [0072]    The mixing chamber  5  includes a wall forming a surface of revolution around an axis  17 . The swept surface of the surface of revolution is at a distance from the axis  17 , in such a manner that a central hole  18  crosses the mixing chamber  5 , as illustrated on  FIGS. 1 to 6 . 
         [0073]    The outlet  15  of the tubular duct  7  tangentially opens into the mixing chamber  5 , as illustrated on  FIG. 2 . 
         [0074]    According to a second embodiment, illustrated on  FIG. 3 , the tubular duct  7  penetrates tangentially and extends in the mixing chamber  5  in such a manner that the outlet  15  is in fluid communication with the inside of the chamber  5 . 
         [0075]    According to the first and second embodiment, the burner  1  comprises a lower part (A) and an upper part (B) made of deep drawn steel sheet or aluminum. A burner head  19  constitutes a part (C) of the wall of the mixing chamber  5 , as illustrated on  FIG. 1 . 
         [0076]    The burner head  19  includes a shoulder  21 . As illustrated on  FIG. 1 ; the shoulder  21  is annular and located in the periphery of the mixing chamber  5  in such manner as to define an overhang from the burner head  19  in the extension direction of the flame. 
         [0077]    The burner head  19  includes a plurality of openings  22  in fluid communication with the outside. 
         [0078]    A first area  23  of the burner head  19  surrounds the central hole  18  and comprises openings  22  the dimension of which is between 0.8 and 1.5 mm. The distance separating the openings of the first area is between 1.5 and 2.5 mm. The first area  23  is an annular surface partly comprised in a plane which is perpendicular to the axis  17  or slanted by an angle of at least 10° in such a manner as to have an overhang from the periphery of the area  23  in the extension direction of the flame. 
         [0079]    An area width is defined as the difference of length between a maximum radius of the area, and a minimum radius of the area, with respect to the axis  17 . The width of the first area D1 is between 3 and 15 mm. 
         [0080]    A second area  25  surrounds the first area  23  and comprises openings  22  the dimension of which is between 0.8 and 1.5 mm. The distance separating the openings of the second area is between 1.5 and 2.5 mm. The width of the second area D2 is between 5 and 15 mm. 
         [0081]    The second area  25  comprises an internal annular surface  27  around the axis  17 . The internal surface  27  is slanted by an angle of 30 to 60° with respect to a plane perpendicular to the axis  17  in such a manner as to have an overhang from the periphery of the internal surface  27  in the extension direction of the flame. 
         [0082]    The internal surface  27  constitutes the edge of the annular shoulder  21 . 
         [0083]    The second area  25  comprises an upper annular surface  29  surrounding the internal surface  27 . The upper surface  29  is slanted by an angle of 0 to 10° with respect to a plane which is perpendicular to the axis  17  in such a manner as to have an overhang from the periphery of the upper surface  29  in the extension direction of the flame. 
         [0084]    An intermediate area  31  is located between the first area  23  and the second area  25 . The intermediate area  31  is an annular surface according to a plane which is perpendicular to the axis or slanted by an angle of at least 10° in such a manner as to have an overhang from the periphery of the intermediate area  31  in the extension direction of the flame. 
         [0085]    The surface of the intermediate area is solid, by solid is meant without an opening. The width of the intermediate area Di being between 5 and 15 mm. 
         [0086]    The periphery of the burner head  19  has a peripheral wall forming a crown the edge  32  of which is disposed beyond the surface of the shoulder  21  in the extension direction of the flame, such as illustrated in  FIG. 1 . 
         [0087]      FIG. 8  has a detail  52  of  FIG. 7 . 
         [0088]    As illustrated on  FIG. 8 , the crown has a radial surface  53 . The upper part of the mixer and the mixing chamber (B) comprises a flange  55  surrounding the radial surface  53 . The distance separating the flange  55  from the radial surface  53  is 1.5 mm. 
         [0089]    An annular peripheral chamber  57  is located between the flange  55  and the radial surface  53 . An annular slit  59  adjoins the edge  32  of the crown. 
         [0090]    The flange  55  has an upper rim  61 . The rim  61  is slanted in the direction of the edge  32  of the crown in such a manner as to partially close the peripheral chamber  57 . The width of the slit is 0.9 mm. 
         [0091]    As illustrated on  FIGS. 7 and 8 , the radial surface  53  has round openings  63  with a diameter of 1.5 mm putting the mixing chamber  5  and the peripheral chamber  57  in fluid communication. 
         [0092]    As shown on  FIGS. 5 and 6 , the burner is included within a portable stove  33 , in such a manner that the burner head  19  is in fluid communication with the outside. 
         [0093]    A cup  35 , having a central opening surrounds the burner head, as illustrated by  FIGS. 5 and 6 . The cup  35  has a shoulder  37  in such a manner that the shoulder  37  forms a throat  39  set back with respect to the burner head  19 . The throat  39  is oriented in the opposite direction to the extension direction of the flame, as illustrated on  FIG. 5 . 
         [0094]    The throat  39  is surrounded by an elevated edge  41  with respect to the burner head  19  in the extension direction of the flame. 
         [0095]    A support for a cooking recipient  43  includes means for fixing to the portable stove  33 . The support  43  is positioned on the portable stove  33  in such a manner as to surround the burner head. 
         [0096]    The support  43  extends in the extension direction of the flame in such a manner as to have an overhang with respect to the burner head  19 . The support  43  is intended to maintain a cooking recipient  45  at a minimum distance of 10 mm from the burner head. 
         [0097]    The support  43  comprises fins  47  of convex shape facing the burner head and concave shape on the opposite face. The support has openings  48  between the fins. The fins  47  make the connection between a lower crown  49  and an upper crown  51 , the lower crown  49  and the upper crown  51  being comprised in the support  43 . 
         [0098]    The cooking recipient  45  is intended to rest on the upper crown  51  and the lower crown  49  is secured to the portable stove. 
         [0099]    The gas burner  1  according to the present invention creates flames that have a reduced length, allowing a distance of the order of 10 to 15 mm minimum between the cooking recipient  45  and the burner head  19 . 
         [0100]    A flow of a gas/air mixture is injected at the inlet  11  of the mixer  3 . The speed of the flow of the gas/air mixture increases when passing through the Venturi effect structure  16 . 
         [0101]    The flow of the gas/air mixture penetrates tangentially in the mixing chamber  5 . The flow is then distributed in the chamber  5  while forming a swirl. The flow exits the chamber  5  by the openings  22  of the burner head  19  by decomposing into a plurality of streams. 
         [0102]    The arrangement of openings  22  of the first area  23  and second area  25  conditions the formation of a plurality of flames of reduced size. 
         [0103]    The combustion reaction causing the flames is initiated by an input of intermittent energy, such as a spark. Once the reaction initiated, the flames stabilize outside the burner  1  at the openings  22 . As illustrated by  FIG. 4 , the flames move away from the burner according to the axis  17 . 
         [0104]    The speed of the streams of the gas/air mixture exiting the mixing chamber is substantially equal to the speed of flammability. Thus, the flame stabilizes at the burner head. 
         [0105]    The shoulder  21  of the burner head  19  and the fact that the intermediate area  31  is without an opening  22  promotes the addition of secondary air to the gas/air mixture coming from the chamber  5 . 
         [0106]    The secondary air comes from the outside and is suctioned through the central hole  18 . The suction is caused by the circulation of the gas/air mixture exiting the chamber  5 . 
         [0107]    The elevated edge  41  of the cup  35  has a protective role against the wind by limiting the risks of the flame from being blown out. 
         [0108]    The fins  47  of the support  43  by their convex shape facing the burner head, facilitate the discharge of the burnt gases from combustion by the openings  22 . 
         [0109]    The concave shape of the external faces of the fins  47  limits the penetration of the wind into the area delimited by the support  43 . 
         [0110]    As it is known per se, the invention is not limited to the sole embodiment of this device, described above by way of example, but on the contrary it encompasses all variants.