Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
  • F23D14/04—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner
  • F23D14/08—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner with axial outlets at the burner head
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
  • F23D2900/14—Special features of gas burners
  • F23D2900/14062—Special features of gas burners for cooking ranges having multiple flame rings

Definitions

• the present invention concerns a gas burner for cooking hobs, in particular domestic cooking hobs, of the so called "flat" type, in which the flame holes, that is the outflow sections of fuel mixture, of at least one flame spreader, are substantially tilted with respect to the horizontal line of an angle comprised between 0° and 30°, so that the flames produced by such a flame spreader will leave from the latter along a substantially vertical axis.
• outflow sections substantially tilted with respect to the horizontal line of a certain angle
• outflow areas of mixture composed of fuel gas/primary air of the flame spreaders of a certain flame spreader will substantially lie on curved planes, or surfaces, with a wide curvature radius then being similar to planes inclined of the reported angle with respect to the horizontal line.
• flame hole it is meant every opening having a section of any shape, obtained in the flame spreader and designed to deliver the mixture composed of fuel gas/primary air to be ignited.
• flame holes could have any geometrical shape, for example they can have an oval or rectangular or circular shape, and preferably they have an outflow section of the fuel mixture that is substantially flat, even if the section is not necessarily obtained on a flat surface.
• Such a burner type which is usually named "flat” burner, has a flame spreader comprising at least one horizontal surface, or zones tilted of few degrees with respect to the horizontal line, on which there are the aforesaid outflow sections of the fuel mixture that, when the burner is ignited, produce a plurality of flames departing substantially vertically from the flame spreader and that are usually close one to another.
• the European Patent EP-A-1249665 in the name of WHIRPOOL teaches to implement a similar burner in which the flame spreader, being dome shaped, has a plurality of slits with a substantially horizontal outlet section composing the flame holes of the aforesaid burner.
• Such a burner type for cooking hobs usually fed through a mixer for example of the Venturi type, which feeds a mixture of fuel gas/primary air to a distribution chamber obtained in the burner body and fluidically connected to the aforesaid flame spreader, usually has the drawback that, because of the arrangement of the flames and their nearness one to another in such a burner, the inflow of secondary air to the flames, which is necessary to have the correct stoichiometric relation between the fuel gas and oxygen for the combustion, is usually not sufficient, so that the mixture combustion is not complete or sufficient and could sometime produce unacceptable amounts of noxious substances.
• the inflow of secondary air at the holes of the flame/s, which are placed in the interior on the flame spreader is usually impeded, or impaired, by the flames emanating to the outside on the same flame spreader.
• the Patent Application EP-A-2072901 in the name of CANDY describes a cooking hob provided with "flat" burners which have, in a central position with respect to the flame spreaders, an opening for feeding secondary air supplied through a forced ventilation system.
• the flow of secondary air being just a forced flow, can be accurately adjusted so that the combustion of fuel mixture in the aforesaid burners will be substantially optimal.
• such a result is obtained with a great increase of the complexity of the cooking hob and then of the final cost of such a component.
• the use of an equipment for producing a flow of forced air obviously decreases the overall reliability of the cooking hob.
• the Australian Patent AU-B-312372 in the name of MALLEYS Ltd. describes a burner provided with flame holes which have substantially horizontal outflow section, the burner having, at the upper lid of the burner, in the center of the flame holes, an opening for feeding the secondary air.
• Such an opening is connected, through a ductwork extending inside the burner body and the respective cup, to a zone beneath the burner cup, and then beneath the cooking hob, from which therefore the secondary air flows.
• a further object of the present invention is to provide a burner of the afore referred type having an effective combustion of the fuel mixture feeding it, without the need to be coupled to complex devices of forced ventilation for its operation.
• the gas burner according to the present invention comprises a burner cup provided with at least one ejection nozzle of the fuel gas, which is integral with a cooking hob or provided with means for the connection to the latter; at least one mixer of the fuel gas with primary air placed downstream of the ejector nozzle and fed with fuel gas through such a nozzle; a burner body removably coupled to the cup of the burner and comprising at least one distribution chamber for the mixture composed of fuel gas/primary air placed downstream of the mixer; and at least one flame spreader, coupled to the aforesaid distribution chamber, which is provided with flame holes having respective outflow sections lying substantially on one or more planes inclined of an angle comprised in the range 0° - 30°, that is an angle greater or equal to 0° and lower or equal to 30°, with respect to the horizontal line, and in which such a flame spreader has a preferably annular shape,
• the burner body comprises at least part of the structure of at least one inflow ductwork for the flow of the secondary air towards said central opening for the outflow of the secondary air, and such an inflow ductwork of secondary air has its own drawing section to draw secondary air which opens over the cooking hob.
• the draw of secondary air from above the cooking hob preferably in a zone sufficiently distant from the flame holes, far from being ineffective, allows a sufficient intake of secondary air to the flames of the afore described "flat" burner and then an effective combustion of the fuel mixture.
• the drawing section of the inflow ductwork of secondary air opens at a distance from the central opening for the outflow of secondary air and from the flame holes of the flame spreader and in particular, preferably, it opens at a distance greater than 10 mm from the closest flame hole.
• the burner comprises at least one inflow ductwork for the primary air, fluidically connected to the aforesaid mixer, having the drawing section to draw primary air indifferently placed over or beneath the cooking hob.
• drawing section is meant the area of that opening directly belonging, or anyway fluidically connected, to the respective ductwork, which allows the income of primary or secondary air into the same ductwork.
• drawing section will be completely or only partially obtained in the body or cup of the burner, or it will be obtained in the cooking hob or made in a body coupled to the burner, as long as fluidically connected to the respective inflow ductwork.
• the aforesaid mixer can be a mixer with Venturi effect with radial expansion or a mixer with Venturi effect with axial expansion.
• FIG. 1 shows a gas burner for cooking hobs according to a particular embodiment of the present invention seen in a top plan view;
• FIG. 2 is a side section view according to the line A-A of figure 1 of the gas burner of the preceding figure;
• FIG. 3 is a side section view according to the line B-B of the gas burner represented in figures 1 and 2;
• FIG. 4 is a perspective view of a gas burner for cooking hobs according to a different embodiment of the present invention.
• figure 5 is a side section view of the gas burner shown in figure 4.
• the gas burner 1 for cooking hobs 2 depicted in figures 1-3 comprises a cup 3 constrained and/or integral to the cooking hob 2, and extended beneath the latter, and having an ejection nozzle 4 for the fuel gas, a body 6.1, 6.2 of the burner, removably assembled on top of the cup 2 and provided with a mixer 7 of primary air I - fuel gas, fluidically placed downstream of the nozzle 4, and at least part of a distribution chamber 8 of the fuel mixture, fluidically placed downstream of the mixer 7, as well as a flame spreader 9 provided with a plurality of flame holes 18, and preferably having a substantially annular shape, placed over the body 6.1, 6.2 of the burner so that to be fluidically coupled to the distribution chamber 8.
• cup of the burner, as the person skilled in the art knows, it is generically meant the burner component intended to be fixed to the cooking hob and arranged to support at least one ejection nozzle of the fuel gas connected to the gas distribution system.
• mixer is meant that component, sometimes associated at least in part with the cup and/or with the body of the burner, and interposed between, or belonging to, such components, that is able to mix the fuel gas coming from the aforesaid nozzle and a flow of primary air coming from the outside of the burner.
• a mixer can be, and preferably is, a Venturi tube of the type with radial expansion or with axial expansion.
• burner body such a component, e.g. coupled by juxtaposing complementary parts to the top of the cup, defining at least a distribution chamber of the mixture, fluidically connected to the outlet section of the aforesaid mixer, arranged to be coupled to a flame spreader.
• flame spreader component of the burner, usually constrained to the top of the burner body and fluidically connected to the aforesaid distribution chamber, having a plurality of flame holes, i.e. holes intended to allow the fuel mixture to be delivered outwards (i.e. the mixture of fuel gas/primary air formed in the mixer), so that the combustion of such a mixture would become possible with the intake of an appropriate volume of secondary air.
• burner components that is the "cup”, the “burner body”, the “mixer” and the “flame spreader” are not necessarily composed exclusively by monolithic bodies, but they can be composed as well by several parts stably assembled or coupled one to another.
• the mixer could be indifferently obtained in the cup and/or the burner body, or else it could be a distinct body, simply coupled to such a cup and/or burner body.
• the cup 3 of the burner is provided with means for connecting to the cooking hob 2, herein not shown, but quite ordinary in burners known in the art, and for example composed of flat springs, and/or threads or bolts and/or embedments through complementary parts, and it is shaped so as to allow the coupling of the body 6.1 , 6.2 of the burner in an upper position.
• Such a cup 3 of the burner composed of an usually metallic hollow body, comprises as well an ejection nozzle 4 of the fuel gas connected, or connectable, to the domestic gas distribution system, which is arranged inside the hollow zone 5 of the cup 3 so as to have the gas ejection axis directed towards the inlet section of the mixer 7 to mix the primary air I with the fuel gas, as will become evident in the following.
• the burner body comprises a first lower component 6.1, on which at least part of a mixer 7 is obtained for mixing primary air I with fuel gas, and a second upper component 6.2 mechanically connected to the upper component, and carrying at least part of a distribution chamber 8 of the mixture of fuel gas/primary air, the chamber being placed downstream of the mixer 7 and fluidically communicating with the latter.
• the mixer 7 is a Venturi effect mixer with radial expansion - also known as "radial Venturi” - comprising, as known in the art, a vertical axis duct tapered upwardly and opening over an expansion chamber with a horizontal development, that is composed of two opposed walls closed one to another, so that the main dimensions of such a chamber lie on a substantially horizontal plane.
• radial Venturi 7 herein illustrated, the tapered duct with vertical axis, together with the lower walls of the expansion chamber, is obtained in the first lower component 6.1 of the burner body, whereas the upper walls of the expansion chamber are obtained in the second upper component 6.2 of said burner body.
• the inlet section of the tapered vertical duct of the radial Venturi 7 opens into a hollow zone 5 defined by the cup 3 so that such an ejection nozzle 4 directs its own flow of fuel gas into such a vertical tapered duct and so that the primary air I reaching the cup 3 is withdrawn, precisely thanks to the Venturi effect, into such a vertical tapered duct.
• the first lower component 6.1 of the burner body is shaped to realize, when coupled to the cup 3 and the cooking hob 2, i.e. to the upper wall of the latter, some ductworks 12.1, 12.2 having respectively a drawing section 13.1, 13.2 of the primary air I placed over the cooking hob 2 and a development, defined by the lower walls of the first component 6.1 of the burner body and by upper walls of the cooking hob 2, that leads the primary air I, withdrawn by the radial Venturi 7, into the concave zone 5 of the cup 3.
• the drawing sections 13.1, 13.2 of the primary air I are preferably placed at a certain distance from the flame spreader 9 and, in particular, from the respective flame holes 18.
• the expansion chamber of the radial Venturi 7, placed downstream of the more restricted section of the vertical tapered duct of the radial Venturi, is placed in fiuidic communication, as mentioned, with a distribution chamber 8 of the fuel mixture, having an annular shape and obtained, at least in part, in the second lower component 6.2 of the burner body.
• the flame holes 18 of the substantially flat flame spreader 9 encircle the central opening 10 intended, as mentioned, for the outflow of secondary air II into the flames giving off from the flame spreader 9.
• the central opening 10, intended to allow the outflow of secondary air II directed towards the flames coming out from the flame spreader 9, is fluidically connected to the ductworks 16.1, 16.2 that are obtained at least in part inside the body of the burner 6.1, 6.2 and respectively have drawing sections 17.1, 17.2 for the secondary air II placed over the cooking hob 2, so as to allow the inflow of secondary air II drawn from these sections 17.1, 17.2 to the central opening 10.
• the drawing sections 17.1, 17.2 of the ductworks 16.1, 16.2 for the secondary air II are placed at a distance from the central opening 10 for the outflow of secondary air II and/or from the flame holes 18 of the flame spreader 9, so as to decrease the influence of flames and the respective heat emitted therefrom on the drawn flow of secondary air II.
• drawing sections 17.1, 17.2 to draw the secondary air II are arranged at a distance greater than 10 mm from the closest flame hole and, in case wherein the burner 1 comprises also a supporting grid 14, 15 for cooking vessels, the drawing sections 17.1, 17.2 of the ductworks 16.1, 16.2 for the secondary air II can be arranged at or beyond such a supporting grid 14 with respect to the flame spreader 9.
• the drawing sections 17.1, 17.2 to draw the secondary air II are preferably arranged at a distance greater than 10 mm from the circumference of the flame holes 18 that is farthest from the central opening 10 for the outflow of the secondary air II.
• the ductworks 16.1, 16.2 for the secondary air II similarly to those 12.1, 12.2 for the primary air, have a structure made at least in part in the body of the burner 6.1, 6.2 and at least in part have a structure comprising as well at least one zone defined at least in part by the cooking hob 2, in particular in the herein represented burner 1.
• the ductworks 16.1, 16.2 for the secondary air II are respectively composed by ductwork lengths obtained in the burner body, thanks to the mutual assembly of the aforesaid first and second component 6.1, 6.2, and by ductwork lengths defined at least on bottom by walls of the cooking hob 2 and, on top, by lower walls of a supporting grid 14, 15 for cooking vessels, such as pots or pans.
• the burner 1 may comprise ductworks that, starting from one or more drawing sections to draw atmospheric air which are placed over the cooking hob 2, and commonly to such ductworks, have a branch whereby a part of these ductworks is shaped to direct the (primary) air towards the mixer 7 and another part of these ductworks is shaped to direct the (secondary) air towards the central opening 10 of the burner.
• the herein described burner 1 comprises, according to a particular aspect of the present invention, a supporting grid 14, 15 for cooking vessels, composed of a substantially annular base 14 having resting arms 15 adapted to bear the cooking vessels.
• the drawing sections 17.1, 17.2 of the ductworks 16.1, 16.2 for the secondary air II and, furthermore or alternatively, the drawing sections 13.1, 13.2 of the ductworks 12.1, 12.2 for the primary air I can be obtained in the same supporting grid 14, 15, and in particular in the base 14 of such a supporting grid.
• the burner 1 is further completed, as known in the art, by at least one ignition spark plug and a safety device, for example comprising a thermocouple, in order to avoid gas leakage in case of accidental flame blowing out, herein not represented.
• a safety device for example comprising a thermocouple
• the mixture made by the mixer 7 flows into the distribution chamber 8 obtained in the burner body 6.1, 6.2, and from here it reaches the flame holes 18 of the flame spreader 9.
• a firing for example composed of a spark generated by an ignition spark plug, allows the combustion of the fuel mixture, also due to the presence of atmospheric air constituting the secondary air II for the fuel mixture.
• a gas burner 101 is visible and comprises, similarly to the burner 1 of figures 1 to 3, a cup 103 integral with, or provided with connecting means to, a cooking hob 102 and comprising an ejection nozzle 104 of fuel gas, a mixer 107 of the fuel gas with primary air I, placed downstream of the nozzle 104 and obtained at least in part in the cup 103, a burner body 106, removably coupled to the cup 103, of the burner 101 and comprising at least part of a distribution chamber 108 of the mixture composed of fuel gas/primary air I, placed downstream of the mixer 107, as well as a flame spreader 109 coupled to the distribution chamber 108 and provided with flame holes 118 having respective outflow sections which substantially lie on one or more plane inclined with respect to the horizontal line of an angle between 0° and 30°.
• the flame spreader 109 of the burner 101 identically to the flame spreader 9 of the burner 1, comprises, in a central position, encircled by the flame holes 118, a central opening 110 designed for the outflow of secondary air II directed towards the flames of the same flame spreader 109, and surmounted by a lid 111, the latter being placed at a distance from the opening 110 itself in order to allow the flow of secondary air II.
• the burner 101 comprises as well a ductwork 116, obtained at least in part in the body 106 of the burner, for the inflow of secondary air II that has its own drawing section 117 to draw the secondary air II placed over the cooking hob 2 and connects such a drawing section 117 to the central opening 110 of the flame spreader 109.
• the ductwork 116 for the secondary air II comprises a first length obtained by coupling the body of the burner 106 with the cup 103, that is by coupling the wall belonging to such components of the burner 101, and a second length defined at least in part by the cooking hob 102, and specifically also by walls of a supporting grid 114, 115 for the cooking vessels.
• the respective drawing section 117 to draw secondary air II is realized over the cooking hob 102, between the grid 114, 115 and the upper surface of the cooking hob 2.
• the body of the burner 106 also comprises, in addition to part of the ductwork 116 for the secondary air II, part of the structure of a ductwork 112 for the primary air I, provided with a drawing section 113 to draw the same primary air I placed over the cooking hob 102 and shaped so as to allow the inflow of primary air I into a well 105 placed immediately downstream of the ejection nozzle 104 of fuel gas, defined by the cup 103.
• the ductwork 112 for the primary air I similarly to the ductwork 116 for the secondary air II, is defined in part by the coupling of the body of the burner 106 with the cup 103 and in party by the coupling of the aforesaid supporting grid 114, 115 for cooking vessels with the upper surface of the cooking hob 102.
• the possible arrangement of the drawing section 113 to draw primary air I beneath the cooking hob 102 - herein not shown - falls anyway in the requested scope of protection of the invention.
• the primary air I coming from the ductwork 116 meets the aforesaid well 105 and, downstream of the latter, the mixer 107 composed, in the herein described burner 101, of a Venturi tube with axial expansion - herein named also as axial Venturi - horizontally arranged in the cup 103 and adapted to axially receive the flow of fuel gas emitted from the ejection nozzle 104.
• Such an axial Venturi 107 is composed of a restricted inlet section, placed downstream of the well 105, and an expansion section, composed of a truncated cone duct, whose section gradually widens in the axial direction from the aforesaid restricted inlet section.
• a passage is provided at the outlet of the expansion section of the axial Venturi 107, inside which the just formed fuel mixture passes, the passage being directed to the aforesaid substantially annular distribution chamber 108 defined in part by the body of the burner 106 and in part by the same flame spreader 109, the latter limiting the chamber 108 on top.
• the flame spreader 109 has, as mentioned, a plurality of flame holes 118 having a substantially elliptical shape, communicating with the distribution chamber 118 and disposed around the central opening 110 for the outflow of secondary air II.
• the burner 110 comprises a supporting grid 114, 115 composed of a base 114, shaped to couple with the body of the burner 106 and/or with the cooking hob 2 so that to encircle the flame spreader 9, and of a plurality of resting arms 115 to support a cooking vessel, such a skillet, a pan or similar.
• the base 114 of such a supporting grid defines partially the ductworks 112, 116 for the inflow of primary air I and secondary air II in cooperation with some upper parts of the cooking hob 102.
• At least one ignition spark plug and one safety device for example of the type comprising a thermocouple, herein not represented, complete the burner 101.
• the operation of the burner 101 is completely similar to the operation of the burner 1 and to the latter reference is made.
• the use of a different mixer 107 does not modify the operation tenet of the burner 101 with respect to the afore shown burner 1, as the presence of a different number of ductworks for the primary air I and secondary air II does not modify it.
• the Applicant noticed that the presence of means for allowing the natural inflow of secondary air from the above of the cooking hob towards the center of the flat burner, of the afore defined type, i.e. without the use of devices for causing a forced flow of secondary air or without drawing secondary air from the beneath of the cooking hob, revealed to be able to allow an efficient combustion.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gas Burners (AREA)

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Citations (6)

• 2013
  • 2013-04-17 ES ES13745165T patent/ES2726542T3/es active Active
  • 2013-04-17 EP EP13745165.4A patent/EP2986913B1/en active Active
  • 2013-04-17 PL PL13745165T patent/PL2986913T3/pl unknown
  • 2013-04-17 WO PCT/IB2013/000709 patent/WO2014170707A1/en active Application Filing

Patent Citations (6)

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