MXPA96002043A - Atmospheric gas burner with minimomejor ignition - Google Patents

Abstract

The present invention relates to a gas burner comprising: a burner body having a front divided by a deflector in first and second chambers, a first set of ports formed in said burner body, the first set of ports that are fluid communication with the first chamber, a second set of ports formed in said burner body, the second set of ports that are in fluid communication with the second chamber, and means for channel conduction of a mixture of fuel and air to the first chamber. and second chamber for discharging from the first and second port assemblies during a first mode of operation, and for channeling a fuel and air mixture only to the second chamber for discharge only from the second set of ports during a second mode of operation. operation

Description

ATMOSPHERIC GAS BURNER WITH IMPROVED MINIMUM IGNITION This invention relates generally to atmospheric gas burners, particularly gas burners for domestic kitchen appliances. The invention relates, more specifically, to the improvement of the operating range of gas burners. Atmospheric gas burners are commonly used as surface units in domestic gas cooking appliances. These gas burners typically comprise a burner head having a number of holes formed therein. A mixing tube introduces a mixture of fuel and air in the head of the burner. The fuel-air mixture passes through the holes and ignites and burns. A critical design parameter for atmospheric gas burners is obtaining an adequate operating range or minimum ignition level. The minimum ignition level is of particular importance for gas burners used in gas cooking appliances, since these burners are frequently required to operate over a wide range of consumptions. Many current gas burners are unable to provide a proper simmering operation. This occurs because the minimum ignition level is limited by the minimum speed of the gas in the holes of the burner that can hold a stable flame. When the fuel supply is reduced for the simmering operation, the velocity of the gas through the orifices is lower. Eventually, the gas velocity may become so low as not to produce a flame at all or provide a flame prone to being extinguished by alterations in the environment, such as ambient air currents or knocks on the oven door. The problem is especially evident in so-called sealed gas appliances, ie, burner arrangements that lack an opening in the upper cooking surface around the burner base to prevent spills from entering the area under the cover. of the kitchen, thus facilitating the cleaning of the appliance. Accordingly, there is a need for an atmospheric gas burner capable of obtaining an extended minimum ignition level, while maintaining the appearance, feel and ease of cleaning of conventional surface burners. The aforementioned needs are covered by the present invention, which provides a gas burner comprising a burner body with a plurality of burner orifices formed therein. A deflector located inside the body of the burner divides the interior of the burner body in first and second chambers. The baffle comprises a coupled section having an inlet pipe that projects axially therefrom and a plurality of channels extending radially therefrom. Each of the channels is aligned with one of the holes individually. There are typically at least 24 holes and four channels. The burner also includes a first fuel nozzle aligned with an inlet duct, such as a venturi tube, for supplying fuel to the first chamber. A second fuel nozzle projects into the interior of the burner body and is aligned with the inlet tube of the deflector and, thereby, supplies fuel to the second chamber. During normal operation, the fuel from the first nozzle flows through all the holes, although for the simmering operation the fuel is injected by the second nozzle and flows only through the holes aligned with the channels. Since these are less than the total number of orifices, the velocity of the gas therethrough is greater, and thus a lower minimum ignition level is made possible. In addition, the second fuel nozzle has an injection orifice with a cross-sectional area of smaller size than the injection orifice of the first nozzle of gas. In another configuration, the baffle located within the burner body comprises a cupped section having an inlet pipe projecting therefrom. The outer ring of the cupped section is aligned with the holes to divide each hole into an upper section and a lower section. The lower section of each hole faces a first chamber below the cupped section, and the upper section of each hole faces a second chamber above the cupped section. Preferably, the upper section of each hole comprises approximately one-sixth to one-fourth of the total area of the hole. For normal operation, fuel is discharged from the first nozzle through both the upper and lower sections of the holes. During the simmering operation, fuel is injected into the second chamber by the second nozzle and discharged through the upper sections of the holes only. Other objects and advantages of the present invention will become apparent upon reading the following detailed description, and the appended claims, with reference to the accompanying drawings. The subject that constitutes the subject of this invention is specially indicated and specifically claimed in the conclusion of the report. However, the invention can be better understood with reference to the following description, taken in conjunction with the figures of the accompanying drawings in which t Figure 1 is a cross-sectional top view of a first configuration of a gas burner of the present invention; Figure 2 is a plan view in transverse profile of the gas burner taken along line 2-2 of Figure 1; Figure 3 is a plan view in transverse profile of the gas burner taken along line 3-3 of Figure 1; and Figure 4 is a plan view in transverse profile of a second configuration of a gas burner of the present invention. Referring to the drawings, in which like reference numerals indicate the same elements in all of the various views, Figures 1-3 illustrate an atmospheric gas burner 10 of the present invention. The gas burner 10 is attached to a support surface 12 that forms a portion of the upper face of a gas cooking appliance, such as a stove or an oven. As best seen in Figures 2 and 3, the gas burner 10 is disposed as a misnamed sealed burner. This refers to that there is no opening between the support surface 12 and the base of the burner 10. In this way, the area below the support surface is sealed to prevent spills from penetrating thereby facilitating the cleaning of the surface from the kitchen. However, it should be understood that the present invention is not limited to use in sealed burner artifacts, but is equally applicable to other types of gas cooking appliances. The gas burner 10 comprises a burner body 14 which is preferably, but not necessarily, cylindrical. The burner body 14 has a substantially cylindrical side wall 16, a lower portion 18, and an upper portion 20 defining a hollow interior. Although a type of burner is described and illustrated, the present invention is applicable to other types of burners, such as stamped aluminum burners and orifice burners mounted separately, among others. On the side wall 16 a plurality of holes of the burner 22 are formed. According to the use given herein, the term "orifice" refers to an opening of any shape from which a flame can be held. The holes 22 of the burner are distributed around the circumference of the side wall 18 at or near the upper portion 20 and are typically, although not necessarily, evenly spaced. Usually, the total number of burners 22 will be in the range of about 24-30. Although all these holes 22 are essentially identical in shape, some differ in the way they are fueled, as described below. A mixing tube 24 (illustrated in Figure 2) such as a venturi tube, has an inlet port located externally with respect to the burner body 14 and is connected to an opening in the lower portion 18 to form an inlet duct towards the interior of the burner body 14. A first fuel nozzle, or primary fuel nozzle 26, is located adjacent to the mixing tube 24 and has an injection orifice 28 aligned with the inlet mouth of the mixing tube 24 so that the fuel discharged from the injection port flows into the mixing tube 24. The primary air to sustain combustion is obtained from the ambient space around the burner 10 and is drawn by the fuel jet in a conventional manner through the open space surrounding the mouth of the inlet of the mixing tube 24. In this way, the mixing tube 24 introduces an air-fuel mixture inside the body of the burner 14. U No second fuel nozzle or simmering 30, having an injection orifice 32, is arranged to project axially through the lower portion 18 of the burner body 14 whereby the injection orifice 32 is located within the burner body 14, in ascending direction. The second fuel nozzle 30 is preferably located in the center of the lower portion 18, while the first fuel nozzle 26 is located offset from the center. The second injection port 32 has a substantially smaller cross-sectional area than that of the first orifice 28. An internal baffle 34 is disposed within the burner body 14. The baffle 34 includes a preferably cylindrical cupped section 36 located in the upper portion of the inside the burner body. The cupped section 36 is located concentrically with respect to the body of the burner 14 to divide the interior of the burner body 14 into a first chamber 38 outside the cupped section 36 and a second chamber 40 within the cupped section 36. An inlet tube 42 projects axially from the bottom of the cupped section 36. The inlet tube 42 extends towards the vicinity of the second fuel nozzle 30 so that the injection port 32 is aligned with the inlet tube 42. The unloaded fuel by the second hole injection 32 will therefore flow into the inlet tube 42, drawing air from the first chamber 38 (air enters the first chamber through the mixing tube 24). In this way, the inlet tube 24 introduces a fuel-air mixture into the second chamber 40. The deflector 34 also includes four channels 44 extending radially from the side of the cupped section 36. The channels 44 are, preferably, spaced evenly around the cupped section 36. Each of the channels 44 is aligned with one of the holes of the corresponding burner 22. In this way, the four holes aligned with the channels 44, hereinafter referred to as burner holes for simmering, are fluidly connected with the second chamber 40, while the remaining holes, hereinafter referred to as burner orifices. primary, are in direct fluid communication with the first chamber 38. In addition, the simmering burner orifices are in fluid communication with the first chamber 38 because part of the fuel-air mixture of the first chamber 38 enters the chamber. second chamber 40 by the inlet tube 42. However, the fuel-air mixture injected into the second chamber 40 from the second orifice 32 will not flow back to the first chamber 38 during operation. Therefore, the primary holes are isolated from the second chamber 40. This is how the primary orifices are in fluid communication with the first chamber 38, and isolated from the second chamber 40, and the simmering orifices are in communication fluid with both the first and the second chamber 38, 40. Although four channels 44 and, consequently, four cooking holes at low heat are illustrated and described, the present invention is not necessarily limited to four of these elements. However, the number of cooking holes at low heat will be considerably less than the number of primary orifices. Both the first fuel nozzle 26 and the second fuel nozzle 30 are connected to a gas supply source by means of a two-stage valve 48 (illustrated schematically). The valve 48 is controlled in a known manner by a corresponding control knob on the gas cooker to regulate the flow of gas from the source 46 to the fuel nozzles 26, 30. The two-way valve 48 is of a type well known in the art and has a first stage in which a variable fuel flow rate is fed to the first fuel nozzle 26 and a second stage in which a flow rate of variable flow to the second fuel nozzle 30. The operation range of the valve 48 is as follows »When it is fully open, the valve 48 lowers, the fuel pressure is reduced to a point such that a minimum pressure of first stage. After further reduction from this point, the valve 48 is converted to the second stage in which the fuel is initially supplied to the second fuel nozzle 30 at maximum pressure. The minimum ignition level of the valve 48 in the second stage reduces fluid pressure until the burner 10 is turned off. The first orifice 28 is of a suitable size to produce the maximum desired consumption volume at maximum pressure, and the second orifice 32 is sized appropriately, preferably, to produce the same maximum pressure feed volume as the first orifice 28 produces at the minimum pressure of the first stage. For this to occur, the ratio between the cross-sectional area of the first orifice with respect to the cross-sectional area of the second orifice must be approximately equal to the minimum ignition ratio for a single stage. In operation, the control knob on the gas cooking appliance corresponding to the burner desired gas 10 is actuated, thereby causing the valve 48 to supply fuel to one of the two fuel nozzles 26, 30. For normal operation, the valve 48 is adjusted to the first stage and the fuel is directed towards the first nozzle of fuel 26. This fuel is discharged from the first orifice 28, entrains air for combustion, and enters the mixing tube 24. The fuel-air mixture flows into the first chamber 38 through the mixing tube 24 and most of the The mixture is discharged through the primary burner orifices for combustion. The remainder of the fuel-air mixture of the first chamber 38 flows through the inlet tube 42 of the internal baffle 34 towards the second chamber 40 for discharge through the burner orifices for simmering. Although there is a slight additional flow restriction to the mixture passing through the baffle 34, the normal operation of the burner 10 of the present invention is essentially indistinct with respect to a conventional burner. For the practice of simmering with extended minimum ignition, the valve 48 adjusts to the second stage, directing the fuel accordingly to the second fuel nozzle 30. Then the fuel is discharged by the second orifice 32. This jet of fuel drags air from the second chamber 40, and the subsequent fuel-air mixture is directed towards the inlet tube 42 to reach the first chamber 38. From there, the fuel-air mixture flows through the channels 44 and is discharged through the holes of the burner for fire cooking. slow for combustion. A higher velocity of passage through the orifice is maintained for the same rate of supply to the burner because only the four simmering holes are open to the flow, instead of all of the 24-30 holes. A greater speed in the orifice produces a more stable flame, thus improving the overall minimum ignition level. The operation of the burner 10 is illustrated by means of an example in which the first orifice 28 has a suitable size to provide a feed coefficient of 9,600 UTB / h at a maximum pressure of 4 inches of water column and a feed coefficient of 1,200 UTB / ha at a minimum pressure of 0.0625 inches of water column. Then, if the second orifice is just sized to provide the same feed rate at the maximum pressure, what the first orifice 28 supplies at the first stage minimum pressure (i.e., has a cross-sectional area of approximately one eighth of the transverse profile of the first hole 28), that will produce a feed coefficient of 1,200 UTB / h at the maximum pressure and a Feeding coefficient of 150 UTB / h at minimum pressure. Consequently, the overall operating range of the burner 10 would be in the range of approximately 150-9,600 UTB / h. These values are given by way of example only to demonstrate the minimum possible ignition level of the burner 10 and is not intended to constitute a limit to the present invention. Figure 4 illustrates an atmospheric gas burner 110 which constitutes a second configuration of the present invention. The gas burner 110 is attached to a support surface 112 that forms a portion of the upper part of the kitchen appliance, which may be a cooker or a cooktop. The gas burner 110 comprises a preferably cylindrical burner body 114 having a substantially cylindrical side wall 116, a lower portion 118, and an upper portion 120 defining a hollow interior. A plurality of burner orifices 122 is formed in the side wall 116 at or near the upper portion 120 and are typical, although not necessarily, evenly spaced. A mixing tube 124, such as a venturi tube, has an inlet port located externally of the burner body 114 and is connected to an opening in the lower portion 118 to produce an inlet conduit into the interior of the burner body 114. A first fuel nozzle or primary nozzle 126 is located adjacent to the mixing tube 1224 and has an injection orifice 128 aligned with the inlet mouth of the mixing tube 124 so that the fuel discharged from the injection port 128 flows into the mixing tube 124 A second nozzle, or slow cook nozzle 130, having an injection orifice 132 is arranged to project axially through the lower portion 118 of the burner body 114 whereby the injection port 132 is located within the burner body 114, in ascending direction. As in the first configuration, the second injection hole 132 has a cross-sectional area considerably smaller than the transverse profile of the first hole 128. An internal baffle 134 is disposed within the burner body 114. The baffle 134 includes a section preferably in the form of a bowl 136 located in the upper portion of the interior of the burner body. The cupped section 136 is sized and positioned so that its outer edge 137 has contact with the inner surface of the burner body 114. The cupped section 136 thus divides the interior of the burner body 114 into a first chamber 138 below the section 136 and a second chamber 140 above the cupped section 136. An inlet tube 142 projects axially from the bottom of the cupped section 136. The inlet tube 142 extends towards the vicinity of the second fuel nozzle 130 so that the injection port 132 is aligned with the inlet tube 42. The baffle 134 is positioned so that the edge 137 of the cupped section 136 is aligned with the holes 122 of the burner, thereby dividing each hole 122 into upper and lower sections. The upper section of each orifice 122 comprises approximately one-sixth to one-fourth of the total area of the orifice. The lower sections of the holes 122 are in direct fluid communication with the first chamber 138, while the upper sections are in direct fluid communication with the second chamber 140. Furthermore, the upper sections are in fluid communication with the first chamber 138. because part of the fuel-air mixture of the first chamber 138 will penetrate into the second chamber 140 through the inlet tube 142. However, the fuel-air mixture injected into the second chamber 140 from the second orifice 132 will not flow back to the first chamber 138 during operation. Therefore, the lower sections are insulated from the second chamber 140. In this way, the lower sections are in fluid communication with the first chamber 138, although they are isolated from the second chamber 140, and the upper sections are in fluid communication with both the first 138 and the second chamber 140. Both the first fuel nozzle 126 and the second fuel nozzle 130 are connected to a source of gas supply 146 by means of a two-way valve 148 which regulates the gas flow from the source 146 to the two fuel nozzles 126, 130. The valve 148 is equal to the valve previously described with respect to the first configuration. Accordingly, for normal operation, the valve 148 is adjusted to its first stage and the fuel is directed to the first fuel nozzle 126. This fuel is discharged through the first orifice 128, entrains air for combustion and enters the mixing tube 124. The fuel-air mixture flows into the first chamber 138, and most of the mixture is discharged through the lower sections of the holes 122 for combustion. The remaining fuel-air mixture flows through the inlet tube 142 of the internal baffle 134 towards the second chamber 140 to discharge through the upper sections. Although there is a slight restriction of additional flow to the mixture passing through the baffle 134, the normal operation of the burner 110 of the present invention is essentially indistinct with respect to that of a conventional burner For the operation of simmering, or minimum extended ignition level, the valve 148 is adjusted to its second stage, thereby directing the fuel to the second fuel nozzle 130. A fuel-air mixture is directed to then to the inlet tube 142 to reach the first chamber 138. From there, the fuel-air mixture is discharged through the upper sections for combustion. A higher velocity is maintained in the holes for the same burner supply coefficient, since only the upper portion of each orifice is open to the fuel passage, instead of the entire orifice. A greater speed in the orifices produces a more stable flame, thus improving the minimum level of general ignition. The foregoing is the description of a gas burner with a dedicated slow cooker burner arrangement for a better minimum ignition. Although specific configurations of the present invention have been described, it will be apparent to those skilled in the art that various modifications may be made thereto without departing from the spirit and scope of the invention, as determined by the appended claims.

Claims (15)

1. - A gas burner comprising: a burner body having an interior divided into first and second chambers; a first series of holes formed in said burner body, said first series of orifices being in fluid communication with said first chamber and isolated from said second chamber; and a second series of holes formed in said burner body, said second series of orifices being in fluid communication with both said second chamber and with said second chamber.

2. The gas burner according to claim 1, wherein said first series of orifices comprises at least 20 holes and said second series of orifices comprises four orifices.

3. The gas burner according to claim 1, further comprising a first fuel nozzle having a first hole arranged to inject fluid in said first chamber and a second fuel nozzle having a second hole arranged to inject fuel in said second chamber, said second hole having a cross-sectional area smaller than that of said first hole.

4. - A gas burner comprising: a burner body; a plurality of holes formed in said burner body; a baffle located inside said burner body, said baffle comprising a cupped section consisting of an inlet pipe projecting in the axial direction therefrom and a plurality of channels extending radially therefrom, being each of said channels aligned with a single one of said plurality of holes independently; an inlet duct formed in said burner body; and a second fuel injection hole aligned with said inlet pipe.

5. The gas burner according to claim 4, wherein said burner body is substantially cylindrical.

6. The gas burner according to claim 5, wherein said cupped section is substantially cylindrical.

7. The gas burner according to claim 4, wherein said plurality of orifices comprises at least 24 holes and said plurality of channels comprises four channels.

8. - The gas burner according to claim 4, wherein said inlet conduit comprises a Venturi tube.

9. The gas burner according to claim 4, wherein said second fuel injection orifice has a cross-sectional area smaller than the transverse profile area of the first fuel injection orifice.

10. The gas burner according to claim 9, wherein said second fuel injection orifice has the indicated size to produce a supply coefficient at a maximum available pressure equal to that produced by the first fuel injection orifice. at a minimum available pressure.

11. A gas burner comprising: a burner body; a plurality of holes formed in said burner body; a deflector located inside said body of the burner, said deflector comprising a cupped section consisting of an external flange and an inlet pipe projecting therefrom, said outer flange being aligned with said holes in a manner of dividing to each hole in a top section and an interior section; an inlet duct formed in said burner body; a first fuel injection hole aligned with said inlet duct; and a second fuel injection hole aligned with said inlet pipe.

12. The gas burner according to claim 11, wherein the upper section of each orifice comprises approximately one-sixth to one-fourth of the total area of the orifice.

13. The gas burner according to claim 11, wherein said inlet conduit comprises a Venturi tube.

14. The gas burner according to claim 11, wherein said second fuel injection orifice has a cross-sectional area smaller than the cross-sectional area of the first fuel injection orifice.

15. The gas burner according to claim 14, wherein said second fuel injection orifice has the indicated size to produce a feed coefficient at a maximum possible pressure equal to that produced by the first fuel injection orifice. at a minimum available pressure. SUMMARY An atmospheric gas burner produces an improved minimum ignition level by separating a small number of burner orifices for a simmering service. The burner has an internal baffle that includes a cupped section consisting of four channels that project to the outside. Each of said channels is aligned with one of the holes independently. The burner also includes a first fuel nozzle arranged to supply c: o < fuel to all holes in conventional manner and a? a < second fuel nozzle that supplies c: o < fuel to the four holes for simmering exclusively. The second fuel nozzle has an injection orifice with a smaller cross-sectional area than the injection orifice of the first fuel nozzle. Preferably, the second orifice has the indicated size to produce the same feed coefficient at a maximum pressure that produces the first hole at minimum pressure. Using a small number of holes for the simmering function, the gas velocity as it passes through the orifices increases and an improved minimum ignition level is obtained. In another configuration, the deflector divides each hole in upper and lower sections, instead of separating some of the holes. The upper section of each orifice comprises approximately one sixth to one quarter of the total area of the orifice and is used for the simmering function.