Patent Publication Number: US-7901205-B2

Title: Gas burner with multiple concentric flame rings

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of gas burners with multiple concentric flame rings, and it relates more specifically to improvements to those of these burners that comprise:
         a central burner with a central ring of flame orifices, an axial central gas injector for said central burner, and convergent-divergent means forming venturi interposed between the central injector and the central ring of flame orifices, and   an annular outer burner coaxially surrounding said central burner and provided with at least one annular ring of flame orifices, gas injecting means for the annular outer burner, and convergent-divergent means forming venturi interposed between the gas injecting means and the annular ring of flame orifices, and   means for supplying gas to said axial central injector and to said injecting means.       

     BACKGROUND OF THE INVENTION 
     Gas burners of the type considered are already known, in particular from document PCT/FR04/00158 in the name of the Applicant. 
     These known burners have the disadvantage that the annular burner is supplied with an air-gas mixture in a single location of its periphery, so that it does not operate to its optimum. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a gas burner of this type that is more efficient from the energy point of view, namely more powerful with substantially identical dimensions, while being structurally simple and easy to manufacture and assemble. 
     To these ends, a gas burner with multiple concentric flame rings such as mentioned in the preamble is characterized, being arranged according to the invention,
         in that said gas injecting means for the annular outer burner comprise several gas injectors positioned substantially radially around the axial central gas injector, and   in that the convergent-divergent means comprise at least two substantially radial convergent-divergent conduits forming tubular venturis with respective substantially radial spans and emerging in the annular outer burner, said conduits extending substantially coaxially respectively to said radial injectors.       

     By virtue of this arrangement, it is possible to supply a large air-gas mixture flow to the annular burner distributed in several locations of its periphery, so that its operation is optimized as compared with the former arrangement. 
     Such an arrangement allows complete freedom of choice as to the method of supplying gas. A first possibility of an assembly consists in that said means for supplying gas comprise a single tube situated centrally and connected to all the injectors. The burner is then provided with a single gas supply having a single control (single tap) simultaneously supplying the central burner and the annular outer burner. However, provision can also be made for said gas supply means to comprise a first tube connected to the axial central gas injector and a second tube connected to the lateral gas injectors. Each central burner and annular outer burner has its own gas supply with its own control (two respective taps) so that it is possible to achieve different heating at the center and at the periphery (WOK cooking). 
     In a preferred embodiment, the burner has a central base positioned coaxially to the central burner and this base comprises
         a substantially coaxial central bore emerging upward and able to receive said axial central gas injector, and   at least two substantially radial lateral bores emerging laterally while being able to receive respectively the at least two lateral gas injectors positioned substantially radially.       

     It is then possible to arrange the base according to the type of gas supply selected. In the case of a common supply to the two central and annular outer burners, provision is made for the at least two substantially radial lateral bores of the base to communicate with the central bore and for the base to include additionally a connecting bore communicating with the lower end of the central bore and adapted for receiving the end of a gas supply tube. In the case of two distinct supplies, provision is made for the base to have a first connecting bore communicating with the central bore and adapted for receiving the end of a first gas supply tube and a second connecting bore communicating with said lateral bores and adapted for receiving the end of a second gas supply tube. 
     In order to preserve a sufficiently flat general configuration for the burner, it is desirable that the convergent-divergent tubular conduits forming venturis are inclined upward in an outward direction. 
     In this case, it is advantageous for the base to have, at least in its upper part, a substantially truncated conical general shape with a conicity such that the lateral gas injectors are inclined while being substantially coaxial respectively with the convergent-divergent conduits forming tubular venturis. 
     It is desirable, in order to obtain regular operation, for the convergent-divergent conduits forming tubular venturis to be angularly distributed in a substantially equidistant manner. Advantageously, these convergent-divergent conduits forming tubular venturis are between two and five in number, and preferably in practice three in number mutually separated angularly by approximately 120°. 
     In a concrete embodiment, the annular outer burner has two annular rings of flame orifices, inner and outer respectively. 
     Also in a concrete manner, the convergent-divergent means forming venturis interposed between the central injector and the central ring of flame orifices comprise a radial annular divergent component surrounding a central well coaxial with the central injector, so that, in conjunction with the tubular convergent-divergent conduits with a radial span for supplying the annular outer burner, it is possible to produce a gas burner with multiple concentric flame rings that is relatively shallow. 
     Typically, a gas burner arranged as has just been described may have a power of the order of 7 kW, while keeping approximately the transverse dimensions of a current burner with a power of the order of 5 kW. 
     Another valuable feature of the burner arranged according to the invention lies in the possibility of preserving a structural formation similar to that of former burners with a reduced number of constituent parts, such a burner comprising:
         a lower constituent part or pot adapted for being fixed to an upper plate of a cooking appliance substantially coaxial to an opening of said upper plate,   an upper constituent part or head comprising a central part delimited peripherally by a curved lateral wall defining flame openings so as to constitute said central flame ring and an annular part substantially coaxial with said central part and delimited by at least one curved lateral wall defining flame openings so as to constitute said annular flame ring,   a central cap with a substantially discoid shape adapted for covering said central part, and   an annular cap adapted for covering said annular part.       

     In this case, the burner arranged according to the invention is characterized in that
         the pot has a central area arranged so as to support the axial injector and the radial injectors centrally, and   at least the pot and/or the head have/has at least two radiating gutters that extend from said central area or respectively said central part where they emerge and as far as the outer edge of the pot or respectively as far as the annular part with which they communicate, said gutters being closed by the head or pot respectively in the assembly position of said pot and head so as to constitute said convergent-divergent conduits forming tubular venturis with a substantially radial span.       

     In this case, according to a preferred embodiment, provision is made for:
         the pot to have at least two radiating gutters that extend from said central area and that are open respectively upward,   the head to have at least two radiating gutters that extend from said central part and that are open respectively downward, and   the gutters of the pot and the gutters of the head are superimposed pairwise, in the assembly position of said pot and head, so as to constitute said convergent-divergent conduits forming tubular venturis with a substantially radial span.       

     The design of the pot may, for its part, give rise to two possible embodiments according to the general design of the cooking appliance. 
     A first design consists in that the pot has a solid structure and in that at least the pot and/or the head have/has at least two substantially radial grooves, interposed between said gutters, which that extend while emerging between said central area and the outer edge of the pot or head respectively, these grooves being closed by the head or pot respectively in the assembly position of said pot and head in order to constitute passages with a generally radial span adapted for ensuring the supply of primary air from above the upper plate of the cooking appliance. In this case, it is advantageous to provide that:
         the pot has at least two substantially radial grooves, that are interposed between said gutters and that open substantially upward,   the head has at least two substantially radial grooves, that are interposed between said gutters and that open substantially downward,   the grooves of the pot and the grooves of the head are superimposed pairwise in the assembly position of said pot and head, so as to constitute said passages for supplying primary air.       

     Another design consists in that the pot possesses a structure that is perforated at least partially between the gutters and that is adapted for ensuring the supply of primary air from below the upper plate of the cooking appliance. 
     Advantageously in this case, the gutters of the pot extend as far as below the annular part of the head and the annular part of the head possesses a bottom that is provided with openings facing the ends situated radially toward the outside of said gutters of the pot. 
     In the case where the injectors are supported on a common base as indicated above, it is of value for the central area of the pot to have a central opening through which said base supporting the injectors is engaged from underneath the pot, with its upper truncated conical part projecting above said central area and with its lower part subjacent to the pot, said lower part being provided with the connecting bore or bores. 
     In order to facilitate mutual guiding of the pot and head when assembled, and also to ensure their mutual locking in rotation once assembled, provision is advantageously made for the pot and/or the head to have pairs of projecting fingers positioned either side of the respective gutters and adapted for receiving the corresponding gutters of the head and/or the pot respectively. 
     In the preferred concrete arrangement mentioned above, provision is made for the pot and/or the head to have three substantially radial gutters mutually separated angularly by approximately 120° and three substantially radial grooves interposed between said gutters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood on reading the following detailed description of some preferred embodiments given solely by way of non-limiting examples. In this description, reference is made to the appended drawings in which: 
         FIG. 1  is an overall view in perspective from the side of a possible embodiment of a gas burner with multiple flame rings arranged according to the invention; 
         FIG. 2  is a view in diametral section of the burner of  FIG. 1 ; 
         FIG. 3  is a sectional view of a first embodiment of a part of the burner of  FIGS. 1 and 2 ; 
         FIG. 4  is an exploded view in perspective from above of the burner of  FIGS. 1 and 2 ; 
         FIG. 5  is an exploded view in perspective from below of the burner of  FIGS. 1 and 2 ; 
         FIGS. 6A ,  68  and  6 C illustrate a second embodiment of the part of the burner shown in  FIG. 3 , respectively viewed from above and viewed in section along the lines B-B and C-C of  FIG. 6A ; and 
         FIG. 7  illustrates a variant embodiment of the pot of the burner according to the invention shown in a similar representation to that of the pot appearing in  FIG. 4 , but with a different angular orientation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first of all to  FIGS. 1 to 3 , a gas burner with multiple concentric flame rings, denoted in its entirety by the reference  1 , that is the subject of the invention substantially comprises two elementary gas burners nesting one in the other, namely a central burner  2  and an annular outer burner  3  surrounding said central burner  2  coaxially. 
     The central burner  2  comprises:
         a central burner body  4  possessing a central ring of flame orifices  5 ,   a central axial gas injector  6  positioned substantially coaxially to said central burner body  4 , and   convergent-divergent means  7  forming venturi that are interposed between the central injector  6  and the central ring of flame orifices  5 .       

     The annular outer burner  3  coaxially surrounding said central burner  2  comprises:
         an annular outer burner body  8  having at least one inner and/or outer annular ring of flame orifices  9  (in  FIGS. 1 to 5 , two flame rings are provided, an inner one  9   i  and an outer one  9   e  respectively),   gas injecting means  10  that comprise several gas injectors  11  positioned radially around the central axial gas injector  6 , and   convergent-divergent means  12  forming venturi interposed between the gas injecting means  10  and the annular ring of flame orifices  9 , the convergent-divergent means  12  comprising at least two substantially radial convergent-divergent conduits  13  forming tubular venturis with a substantially radial span and emerging in the annular outer burner body  8 , said convergent-divergent conduits  13  extending substantially coaxially with respect to said radial injectors  11 .       

     Finally, the burner  1  has means  14  for supplying gas to said central axial injector  6  and to said injecting means  10 , means  14  for supplying gas that will now be dealt with more explicitly. 
     The arrangement that has just been described leaves complete freedom of choice as to the method of supplying gas. A first assembly possibility consists of said gas supply means comprising a single tube situated substantially centrally and connected to all the injectors. The burner is then provided with a single gas supply having a single control (single tap) simultaneously supplying the central burner and the annular outer burner. However, provision may also be made for said means for supplying gas to have a first tube connected to the central axial gas injector and a second tube connected to the lateral gas injectors. Both the central burner and the annular outer burner have their own gas supply with its own control (two respective taps) so that it is possible to perform different heating at the center and the periphery (WOK cooking). 
     In this context, in order, at the same time, to simplify the structure of the burner and the assembly of its constituent parts, it is of value for the means  14  for supplying gas to have a central base  16  positioned coaxially to the central burner  2  and arranged so as to support all the gas injectors in their appropriate respective locations. To this end, provision is made for this base  14  to have, as may be seen in  FIG. 3  and in  FIGS. 6A to 6C :
         a substantially coaxial central bore  15  emerging upward and adapted for receiving said central axial gas injector  6 , and   at least two substantially radial lateral bores  18  emerging laterally while being adapted for receiving respectively the at least two lateral gas injectors  11  positioned substantially radially.       

     It is then possible to arrange the base  16  according to the type of gas supply selected. In the case of a common supply for the central burner  2  and the annular outer burner  3 , provision is made, as shown in  FIG. 3 , for all the substantially radial lateral bores  18  to communicate with the central bore  15  and for the base  16  to have additionally a connecting bore  17  communicating with the lower end of the central bore  15  and adapted for receiving the end of a gas supply tube (not shown). The central burner  2  and annular outer burner  3  are then controlled simultaneously from a single tap (not shown). Another possibility of an arrangement of the base  16  will be described hereinafter with regard to  FIGS. 6A to 6C . 
     It should be emphasized here that the base  16  is shown in  FIG. 3  in two sectional planes offset angularly so that its upper part is sectioned in the axis of a lateral bore  18  and its lower part is sectioned in the axis of the bore  17  for connecting a gas supply tube. In addition, in  FIG. 2 , a single injector  11  is shown in position on the base  16 , while the other injector is not mounted and allows the corresponding bore  18  to be seen. 
     In order to lead the air-gas mixture to the annular outer burner  8  that is situated substantially above the radial injectors  11 , it is desirable to avoid elbowed paths in order to reduce pressure losses. Under these conditions, provision may advantageously be made for the convergent-divergent conduits  13  forming tubular venturis to be inclined upward in an outward direction as may be seen in  FIG. 2 . Each conduit  13  is then substantially rectilinear. In this context, the design of the burner may be simplified by providing for the base  16  to have, at least in its upper part, a substantially truncated conical general shape with a conicity such that the lateral gas injectors  11  are inclined while being substantially coaxial respectively to the convergent-divergent conduits  13  forming tubular venturis. 
     In addition, as will be better seen in  FIG. 2 , the convergent-divergent conduits  13  reach under the annular burner body  8 , which possesses a bottom  19  that is provided with openings  20  in correspondence with the ends of the conduits for the passage of the air/gas mixture. 
     In order to obtain a uniform supply of all the annular outer burner  3 , it is desirable for the convergent-divergent conduits  13  forming tubular venturis to be angularly distributed in a substantially equidistant manner. In practice, the burner is easily designed and manufactured when the convergent-divergent conduits  13  forming tubular venturis are between two and five in number. A useful compromise consists of having the convergent-divergent conduits  13  three in number, mutually separated angularly by approximately 120°, as illustrated in the figures. 
     By virtue of the configuration adopted according to the invention, the annular outer burner  3  and the central burner  2  still function substantially independently of each other, since each of them has its own means for supplying an air-gas mixture. On account of this, the central burner  2  may be arranged in any desirable manner that is suitable for requirements. In particular, with a desire to design a shallow burner  1 , it is advantageous for the convergent-divergent means  7  forming venturis interposed between the central injector  6  and the central flame ring  5  to include a radial annular divergent component defined by a plate  21  inclined downward in an outward direction and surrounding a central well  22  coaxial with the central injector  6  and by a face  24  opposite a cap  23  covering the central burner body  4 , as may be seen in  FIG. 2 . 
     It is desirable for the burner according to the invention to retain a simple structure while being made of a minimum number of component parts. From this point of view, it is valuable for it to be made in a similar manner to the burner described in document PCT/FR04/00158 already mentioned. To this end, provision is made for the burner described above to comprise, as may be better seen in  FIGS. 3 ,  4  and  5 :
         a lower constituent part or pot  25  adapted for being fixed to an upper plate  26  of a cooking appliance substantially coaxial to an opening  27  provided in said upper plate  26 ;   an upper constituent part or head  27  comprising:
           a central part forming said central burner body  4 , delimited peripherally by a lateral wall  28  curved in  29 , so as to define, in conjunction with said central cap  23 , flame openings constituting together the abovementioned central flame ring  5 , and   an annular part substantially coaxial with said central part and forming said annular outer burner body  8 , this annular part being delimited by at least one lateral wall  30  curved in  31 , defining, in conjunction with an annular cap  32 , flame openings constituting together said annular flame ring  9  (in the example illustrated, the annular part is delimited by two lateral walls, an inner one  30   i  and an outer one  30   e  respectively, curved in  31   i  and  31   e  respectively, defining, in conjunction with the annular cap  32 , flame openings constituting respectively the two annular flame rings  9   i  and  9   e;      
           said central cap  23  with a substantially discoid shape adapted for covering said central part, and   said annular cap  32  adapted for covering said annular part.       

     In accordance with the arrangement according to the invention, provision is made as follows:
         for the pot  25  to have a central area  33  arranged so as to support the axial injector  6  and the radial injectors  11  centrally, and   for at least the pot  25  and/or the head  27  to have at least two radiating gutters  34  that extend from said central area  33  or respectively said central part forming the central burner body  4  where they emerge and as far as the outer edge of the pot  25  or respectively as far as the annular part forming the annular burner body  8  with which they communicate, said gutters  34  being closed by the head  27  or pot  25  respectively in the assembly position of said pot and head so as to constitute said convergent-divergent conduits  13  forming tubular venturis with a substantially radial span.       

     A simple way to implement the provisions that have just been described consists in that:
         the pot  25  has at least two radiating gutters  34   i  that extend from said central area  33  and that are open respectively upward,   the head  27  has at least two radiating gutters  34   s  that extend from said central part  4  and that are open respectively downward, and   the gutters  34   i  of the pot and the gutters  34   s  of the head are superimposed pairwise, in the assembly position of said pot and head, so as to constitute said convergent-divergent conduits  13  forming tubular venturis with a substantially radial span.       

     In this context, it is conceivable for the pot to be designed according to two possible embodiments leading to two different respective operating modes of the burner according to the design of the cooking appliance. 
     A first embodiment consists, as shown in  FIGS. 1 ,  2 ,  4  and  5 , in that the pot possesses a solid structure and in that:
         at least the pot  25  and/or the head  27  have/has at least two substantially radial grooves  35 , interposed between said gutters  34 , that extend while emerging between said central area  33  and the outer edge of the pot  25  or of the head  27  respectively, these grooves  35  being closed by the head  27  or the pot  25  respectively in the assembly position of said pot and head so as to constitute passages  36  with a generally radial span adapted for supplying primary air from above the upper plate  26  of the cooking appliance.       

     A burner is thus formed wherein the primary air necessary for the functioning of the two burners, a central one  2  and an annular outer one  3  respectively, is supplied from above the upper plate of the cooking appliance. 
     In the specific preferred arrangement shown in  FIGS. 1 ,  2 ,  4  and  5 , the following layouts are used:
         the pot  25  has at least two substantially radial grooves  35   i , that are interposed between said gutters  34   i  and that open substantially upward,   the head  27  has at least two substantially radial grooves  35   s  that are interposed between said gutters  34   s  and that open substantially downward, and   the grooves  35   i  of the pot and the grooves  35   s  of the head are superimposed pairwise in the assembly position of said pot and head, so as to constitute said passages  36  for supplying primary air.       

     A second embodiment consists, as illustrated in  FIG. 7  (in which the same numerical references are retained for denoting elements or parts identical to those corresponding to  FIG. 4 ), in that the pot  25  has a structure that is perforated in  41 , at least partially, between the gutters  34   i . This structure is adapted for ensuring the primary air supply of the two burners, the central burner  2  and the annular outer burner  3 , from below the upper plate of the cooking appliance. 
     Independently of the design of the pot, as is better seen in  FIGS. 2 and 4 , the gutters  34   i  of the pot  25  extend as far as under the annular part of the head  27  and the annular part of the head  27  has its bottom  19  that is provided with the above mentioned openings  20  facing the ends situated radially toward the outside of said gutters  34   i  of the pot  25 . 
     In order to mount the burners, the central area  33  of the pot  25  has, as may be seen in  FIG. 2 , a central opening  37  through which said base  16  supporting the injectors is engaged from underneath the pot  25 , with its upper truncated conical part projecting above said central area  33  and with its lower part subjacent to the pot, said lower part being provided with said bore  17  adapted for receiving the end of a gas supply tube. 
     In the concrete example of an embodiment illustrated in  FIGS. 2 ,  4  and  5 , the pot  25  and/or the head  27  have/has three substantially radial gutters,  34   i ,  34   s  respectively, mutually separated angularly by approximately 120°, and three substantially radial grooves,  35   i ,  35   s  respectively, interposed between said gutters. 
     As will be better seen in  FIGS. 4 and 5 , the implementation of the provisions that have just been described leads to a pot  25  with a solid structure, while the head  27  has a perforated structure, with the gutters  34   s  and grooves  35   s  constituting spokes mechanically connecting the central part to the annular part. 
     In order to ensure correct mutual angular positioning of the superimposed pot  25  and head  27 , provision is made for means for guiding and locking in rotation that, in the example illustrated, comprise pairs of fingers  38  carried for example by the pot  25  and projecting vertically upward, while being positioned either side of the respective gutters  34   i . When the head  27  is mounted, the gutters  34   s  are each interposed between two facing fingers  38 . An inverse arrangement could of course be adopted, with the projecting fingers carried by the head either side of the gutters  34   s.    
     It will be emphasized that an electrical ignition electrode  39  and/or a thermocouple  40  for detecting the presence of flames may, if desired, be installed in the burner  1 , in any suitable location thereof. As an example, the ignition electrode  39  and the thermocouple  40  are shown in the outer edge of the pot  25  in  FIG. 5 , while they are shown in a central position in the pot  25  and in different locations from that in  FIGS. 2 and 4 . 
     If it is desired to have two distinct supplies available for the central burner  2  and annular outer burner  3  respectively, provision is made, as shown in  FIGS. 6A to 6C , for the base  16  to have a first connecting bore  17  communicating with the central bore  15  and adapted for receiving the end of a first gas supply tube (not shown) and a second connecting bore  44  communicating with said lateral bores  18  and adapted for receiving the end of a second gas supply tube (not shown). 
     In the design of the base  16  illustrated by way of example in  FIGS. 6A to 6C , provision is made, as will be better seen in  FIG. 6B , for the axial central bore  15  receiving the axial central injector  6  of the central burner  2  to be connected by a channel  42  offset laterally to the connecting bore  17  which, here, is situated laterally at the bottom of the base  16  and is not radially extended. 
     For their part, the bores  18  of the radial injectors  11  of the annular outer burner  3  are connected by a channel  43  situated axially to a second connecting bore  44  which here also is situated laterally at the bottom of the base  16  and is extended substantially radially. 
     Thus arranged, the base  16  is a relatively complex part with many emerging perforations of which some should then be closed (stoppers  45 ) so as to constitute suitable channels.