Gas burner and heating cooker

Abstract

To enable a gas burner BN to effectively suppress the temperature rise of a backfire suppression plate, the gas burner comprising a burner body 2 comprising a distribution chamber 21 for gas to be supplied thereto via a gas introduction passage 24, a combustion plate 3 covering an open face of the burner body facing the distribution chamber, and a backfire suppression plate 4 disposed in the distribution chamber to face the combustion plate with a gap therebetween, and ejecting / burning gas having flowed through the backfire suppression plate from the combustion plate.SOLUTION: The burner body of the gas burner is constituted by joining a first part 21 provided with a combustion plate and a second part 22 provided with a backfire suppression plate. Heat insulating materials 6a, 6b of lower heat conductivity than that of the second part, are interposed in the joining section between the first part and the second part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gas burner and a cooking appliance suitable for using hydrogen gas as a fuel gas. [Background technology]

[0002] A known example of the above-mentioned gas burner is described in Patent Document 1. This burner includes a burner body having a distribution chamber to which a mixture of fuel gas and primary air is supplied via a gas inlet passage; a combustion plate covering the open surface of the burner body facing the distribution chamber; and a flashback suppression plate disposed in the distribution chamber opposite the combustion plate with a gap therebetween. The flashback suppression plate may be, for example, a sintered sheet formed by sintering a laminate of metal fibers. When the mixture gas is supplied to the distribution chamber via the gas inlet passage, the mixture gas passes through numerous minute gaps in the flashback suppression plate, which are smaller than the flashback limit hole diameter, and then ejects from the combustion plate and burns. As the mixture gas passes through the flashback suppression plate, the contact area with the room-temperature mixture gas increases, suppressing the temperature rise of the flashback suppression plate during combustion.

[0003] In the above-described conventional example, the flashback suppression plate is provided with a frame supporting it joined to a predetermined position on the burner body. Therefore, during combustion in the gas burner, the flashback suppression plate is subjected to not only radiant heat from the combustion plate but also conductive heat from the burner body. When conductive heat from the burner body is applied to the flashback suppression plate, the temperature rise of the flashback suppression plate is not effectively suppressed, resulting in a problem of reduced flame quenching effectiveness for a flame that flashes back into the gap between the combustion plate and the flashback suppression plate (hereinafter referred to as a "flashback flame"). This problem is more pronounced when hydrogen gas is used as the fuel gas because the combustion speed of hydrogen gas is very fast and the combustion near the surface of the combustion plate tends to cause the combustion plate to become very hot. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-173899 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, an object of the present invention is to provide a gas burner that can effectively suppress a temperature rise in a flashback suppression plate portion. [Means for solving the problem]

[0006] To solve the above problems, a first invention of the present application provides a gas burner comprising a burner body having a distribution chamber to which gas is supplied through a gas introduction passage, a combustion plate covering the open surface of the burner body facing the distribution chamber, and a flashback suppression plate disposed in the distribution chamber opposite the combustion plate with a gap therebetween, wherein gas passing through the flashback suppression plate is ejected from the combustion plate and combusted. In a first aspect, the burner body is configured by joining a first section provided with the combustion plate and a second section provided with the flashback suppression plate, and an insulating material having a lower thermal conductivity than the second section is interposed at the joint between the first and second sections. In a second aspect, the burner body is provided with a holding section that holds the flashback suppression plate in the distribution chamber, and an insulating material having a lower thermal conductivity than the burner body is interposed between the flashback suppression plate and the holding section. A second invention of the present application is a cooking appliance comprising the gas burner of the first invention.

[0007] According to the present invention (first invention), the heat conduction from the first part of the burner body to the flashback suppression plate through the second part, which becomes relatively hot during combustion of the gas burner, is suppressed by the heat insulating material. Therefore, the temperature rise of the flashback suppression plate is more effectively suppressed than in the above-mentioned conventional example, and as a result, the flashback flame can be more effectively extinguished.

[0008] In the first aspect of the present invention, the flashback suppression plate preferably divides the distribution chamber into a first chamber communicating with the gas introduction passage and a second chamber communicating with the combustion plate, the total volume being the spatial volume of the first chamber, the second chamber, and the gas introduction passage, the clearance volume being the spatial volume of the second chamber, and the remaining volume being the spatial volume obtained by subtracting the clearance volume from the total volume. This arrangement reduces the explosive energy of the gas even if a flashback flame enters the first chamber, thereby reducing problems such as burnout. Furthermore, providing a heat dissipation section on the surface of the flashback suppression plate facing the first chamber can more effectively suppress temperature increases in the flashback suppression plate.

[0009] In the first aspect of the present invention, the gas supplied to the distribution chamber is preferably fuel gas without primary air mixed therein, and the fuel gas is ejected from the combustion plate section for diffusion combustion. This is advantageous because even if a flashback flame penetrates the first chamber, it is prevented as much as possible from penetrating into the second chamber. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a heating cooker equipped with a gas burner according to an embodiment, with the cooking implement removed; [Figure 2] FIG. 2 is a partially enlarged cross-sectional view of the gas burner shown in FIG. [Figure 3] FIG. 2 is an exploded perspective view of the gas burner shown in FIG. [Figure 4] FIG. 10 is an exploded perspective view of a modified gas burner. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, with reference to the drawings, an embodiment of the gas burner of the first invention and the cooking appliance of the second invention will be described, where the cooking appliance is a rice cooker HC that uses a rice cooker Kt that stores rice and water, and the gas burner BN uses hydrogen gas as fuel gas and performs diffusion combustion of the fuel gas without primary air being mixed in. Note that the "hydrogen" referred to in this invention is not limited to pure hydrogen, but also includes, for example, the addition of a small amount of odorant for flavoring.

[0012] Referring to FIG. 1, a rice cooker HC according to a second embodiment of the present invention includes a rectangular parallelepiped main body 1. The main body 1 includes an upper storage chamber 12 having an opening 11 at its top through which a rice cooker Kt can be stored, and a lower storage chamber 13 that communicates with the upper storage chamber 12 and contains a gas burner BN for heating the rice cooker Kt. A bottom wall 13a, which is one of the exterior walls of the main body 1 that surrounds the lower storage chamber 13, and a peripheral wall 13b, which is the other exterior wall of the main body 1 that surrounds the lower storage chamber 13, extend below the bottom wall 13a, allowing the main body 1 to float above the floor on which it is placed. An air intake 14a is formed in the peripheral wall 13b, which is located below the bottom wall 13a, and another air intake 14b is also formed in the bottom wall 13a. The peripheral wall 13b, which is located below the bottom wall 13a, forms downwardly protruding legs Lp provided on the bottom surface of the main body 1.

[0013] The top surface of the appliance body 1 is provided with an annular protruding wall 15, which forms part of the peripheral wall of the appliance body 1 surrounding the upper storage chamber 12 and defines the opening 11. When the rice cooker Kt is inserted from above through the opening 11 of the appliance body 1, the flange Kf extending radially from the outer periphery of the rice cooker Kt rests on the top surface of the protruding wall 15, and the rice cooker Kt is supported with the portion of the rice cooker Kt below the flange Kf housed within the upper storage chamber 12. The protruding wall 15 has multiple exhaust ports 16 spaced apart in the circumferential direction, through which hydrogen combustion gas produced by the combustion of hydrogen gas is exhausted. During cooking, a lid kd is placed on the top opening of the rice cooker Kt. In addition, the peripheral wall portion 13b surrounding the lower storage chamber 13 of the appliance body 1 is provided with multiple inlet passages 17 spaced circumferentially in a plan view to introduce secondary air toward the hydrogen gas ejected from the combustion plate portion 3 of the gas burner BN.

[0014] 2 and 3, a gas burner BN according to an embodiment of the first invention comprises a burner body 2 having an annular distribution chamber 21 therein, a combustion plate 3 covering the open surface of the burner body 2 facing the distribution chamber 21, and a flashback suppression plate 4 disposed within the distribution chamber 21 opposite the combustion plate 3 with a gap Gp therebetween. The burner body 2 is made of, for example, aluminum die-cast, and is configured by joining a first portion 21 provided with the combustion plate 3 and a second portion 22 provided with the flashback suppression plate 4 in the vertical direction. The first portion 21 of the burner body 2 has an inner annular plate 211 and an outer annular plate 212 that are concentric with each other. An inner frame flange 211b is formed on the outer periphery of the inner annular plate 211, with a stepped portion 211a bending upward and projecting outward. An outer frame flange portion 212b that protrudes inward with an upwardly bent step portion 212a is formed on the inner periphery of the outer annular plate portion 212. The inner annular plate portion 211 and the outer annular plate portion 212 are connected to each other by beam plate portions 213 that connect the inner frame flange portion 211b and the outer frame flange portion 212b in the radial direction.

[0015] The combustion plate 3 is made of, for example, a porous sintered stainless steel and is formed in an annular shape so that it can be inserted from below between the stepped portion 211a of the inner annular plate 211 and the stepped portion 212a of the outer annular plate 212. After being inserted from below between the stepped portions 211a and 212a, the combustion plate 3 is attached to the first portion 21 by spot welding to the inner frame flange 211b and the outer frame flange 212b, respectively. In this embodiment, beam plate portions 213 are provided at 90-degree intervals in the circumferential direction, and four portions defined by the inner annular plate 211, the outer annular plate 212, and the beam plate portions 213 respectively constitute combustion zones 31 of the combustion plate 3. In this case, four introduction passages 17 are provided corresponding to the respective combustion zones 31. The combustion plate portion 3 is not limited to this, but can also be made of, for example, a metal fiber knit made by weaving metal fibers such as heat-resistant steel, a sintered sheet made by sintering a laminate of metal fibers or metal beads, or, for example, a stainless steel plate with a row of multiple flame holes penetrating through the plate in the thickness direction.

[0016] The second portion 22 of the burner body 2 has an annular base plate portion 221 having an opening 221a in the center, an inner cylindrical portion 222 that rises upward from the inner peripheral edge of the base plate portion 221 and on whose upper surface the inner annular plate portion 211 of the first portion 21 is seated, and an outer cylindrical portion 223 that rises upward from the outer peripheral edge of the base plate portion 221 and on whose upper surface the outer annular plate portion 212 of the first portion 21 is seated. The base plate portion 221, the inner cylindrical portion 222, and the outer cylindrical portion 223 define an annular distribution chamber 21 to which hydrogen gas is supplied, and the upper surface facing the base plate portion 221 is an open surface. When the first portion 21 is joined to the second portion 22, the open surface is covered by the combustion plate portion 3. Support legs 23, 23 are provided on the lower surface of the base plate portion 221, and the base plate portion 221 is installed on the inner surface (upper surface) of the bottom wall portion 13a via the support legs 23, 23.

[0017] A bulging portion 224 bulging outward in the radial direction is provided at one circumferential location on the outer cylinder portion 223. A gas introduction passage 24 leading to the distribution chamber 21 is formed within the bulging portion 224, and a connecting pipe 25 is connected to the gas introduction passage 24 from the radial direction. A gas pipe 27 having a gas nozzle 26 at its tip is connected to the connecting pipe 25 (see FIG. 1). Although not specifically shown or described, a valve such as an electromagnetic on-off valve or a gas cock is provided in the gas pipe 27, and hydrogen gas is supplied to the distribution chamber 21 via the gas introduction passage 24 via the valve. Since these components necessary for combustion in the gas burner BN are well known, further description will be omitted. The outer peripheral surface of the inner cylinder portion 222 bulges outward in the radial direction and is provided at predetermined intervals in the circumferential direction with inner holding portions 222a extending columnarly from the base plate portion 221. Outer holding portions 223a bulge radially inward on the inner peripheral surface of the outer cylinder portion 223, and extend columnarly from the base plate portion 221. In this embodiment, the inner holding portions 222a and the outer holding portions 223a constitute the holding portion of the burner body 2 that holds the flashback suppression plate portion 4 inside the distribution chamber 21.

[0018] The flashback suppression plate 4 is formed, for example, by a stainless steel plate with a row of numerous through-holes 41 that penetrate the plate in the thickness direction and are smaller than the flashback limit hole diameter (0.6 mm). The plate is formed in a circular ring shape that can be seated on the inner holding part 222a and the outer holding part 223a. The flashback suppression plate 4 is then attached to the second part 22 by screws, with inner and outer metal retaining rings 5a, 5b interposed between the plate and the outer holding part 223a. The flashback suppression plate 4 is not limited to this, as long as it has numerous through-holes smaller than the flashback limit hole diameter. For example, a sintered sheet formed by sintering a laminate of metal fibers or metal beads, a mesh-like metal body, or porous ceramic can be used.

[0019] When joining the first portion 21 including the combustion plate 3 and the second portion 22 including the flashback suppression plate 4, aluminum die-cast insulators 6a and 6b with lower thermal conductivity than the second portion 22 are interposed at the joint between the first portion 21 and the second portion 22—specifically, between the lower surface of the inner annular plate 211 of the first portion 21 and the upper surface of the inner cylindrical portion 222 of the second portion 22, and between the lower surface of the outer annular plate 212 of the first portion 21 and the upper surface of the outer cylindrical portion 223 of the second portion 22—and then the first portion 21 and the second portion 22 are fastened together with screws. The insulators 6a and 6b may be made of ceramic wool, such as alumina wool or silica wool. In this embodiment, the single insulators 6a and 6b also serve to ensure a seal at the joint between the first portion 21 and the second portion 22. It is also desirable to use screws that fasten the first portion 21 and the second portion 22 together using a material that has a lower thermal conductivity than the second portion 22.

[0020] When the first portion 21 and the second portion 22 are joined with the thermal insulators 6a and 6b interposed therebetween, the distribution chamber 21 is divided by the flashback suppression plate 4 into a lower first chamber 21a that communicates with the gas introduction passage 24 and an upper second chamber 21b that communicates with the combustion plate 3. Here, the spatial volume within the burner body 2, which is the sum of the first chamber 21a, the second chamber 21b, and the gas introduction passage 24, is defined as the total volume, the spatial volume of the second chamber 21b is defined as the gap volume, and the spatial volume remaining after subtracting the gap volume from the total volume is defined as the residual volume. The heights of the inner holding portion 222a and the outer holding portion 223a from the base plate 221, the thicknesses of the thermal insulators 6a and 6b, and the height of the gap Gp are appropriately set so that the flashback suppression plate 4 is positioned so that the gap volume is equal to or smaller than the residual volume. Furthermore, a known paint 42 having excellent heat dissipation and heat insulation properties is applied to the upper surface of the flashback suppression plate 4 located on the first chamber 21a side, thereby forming the heat dissipation portion of this embodiment.

[0021] Although not specifically shown or described, a control box incorporating a control board that receives power from, for example, a battery and controls the operation of the gas burner BN is provided on the outer surface of the appliance body 1 of the cooking appliance HC. A mounting plate 28 is provided on the bulging portion 224 of the outer cylinder 223, and a pair of rod electrodes 7 are attached to the mounting plate 28. When a valve disposed on the gas pipe 27 is opened, hydrogen gas is supplied to the first chamber 21a of the distribution chamber 21 in the burner body 2 through the gas inlet passage 24. The hydrogen gas passes through the through-hole 41 in the flashback suppression plate 4 and flows into the second chamber 21b of the distribution chamber 21, and is ejected from the combustion plate 3. At the same time, secondary air is introduced through the respective inlet passages 17 corresponding to the combustion zone 31. At this time, secondary air is introduced from the air intakes 14a and 14b through the inner space of the inner cylinder 222.

[0022] A high voltage is applied between the pair of rod-shaped electrodes 7 from an igniter (not shown) controlled by a control board, and the resulting pyrotechnic discharge ignites the hydrogen gas, causing it to diffuse and burn. As a result, the bottom of the rice cooker Kt is heated by the hydrogen flames generated in each combustion zone 31, and the hydrogen combustion gas generated by the combustion of the hydrogen gas is heated by the hydrogen combustion gas as it is exhausted along the outer peripheral wall of the rice cooker Kt to the exhaust port 16. In this embodiment, the exhaust port 16 is formed to straddle adjacent combustion zones 31 in a plan view so that the hydrogen combustion gas flows evenly around the rice cooker Kt.

[0023] According to the above embodiment, the heat conduction from the first portion 21 of the burner body 2 to the flashback suppression plate 4 via the second portion 22, which becomes relatively hot during combustion of the gas burner BN, is suppressed by the heat insulating materials 6a and 6b. Therefore, the temperature rise of the flashback suppression plate 4 is more effectively suppressed than in the conventional example, resulting in a more appropriate flashback extinguishing effect. Since the paint 42 is applied as a heat dissipation agent to the surface of the flashback suppression plate 4 facing the first chamber 21a, the temperature rise of the flashback suppression plate 4 is more effectively suppressed. Furthermore, even if a flashback flame penetrates the gap Gp between the combustion plate 3 and the flashback suppression plate 4 (i.e., the first chamber 21a), the explosion energy of the fuel gas can be reduced, thereby reducing problems such as burnout. Furthermore, because hydrogen gas is ejected from the combustion plate 3 and diffused and combusted, even if a flashback flame penetrates the first chamber 21a, the invading flashback flame is prevented from further penetrating into the second chamber 21b.

[0024] Although the first and second aspects of the present invention have been described above, they are not limited to these. In the above-described embodiment of the first aspect of the present invention, the heat insulating materials 6a, 6b, which also have a sealing function, are interposed between the first portion 21 and the second portion 22. However, the present invention is not limited to this, as long as the heat conductive material can suppress the heat transfer from the burner body 2 to the flashback suppression plate 4 during combustion of the gas burner BN. For example, a packing that exhibits a sealing function and the heat insulating materials 6a, 6b can be interposed in a stacked state.

[0025] Furthermore, as in the gas burner BN according to a modified example shown in FIG. 4, heat insulating materials 60a, 60b having a lower thermal conductivity than the burner body 2 can be interposed between the flashback suppression plate 4 and the inner and outer holding parts 222a, 223a. In FIG. 4, the same components and parts as those in the first embodiment of the present invention are denoted by the same reference numerals. The heat insulating materials 60a, 60b are made of, for example, stainless steel or ceramic wool. The heat insulating materials 60a, 60b are then molded to have the same contours as the inner and outer holding rings 5a, 5b, respectively, and seated on the upper surfaces of the inner and outer holding parts 222a, 223a, respectively. The flashback suppression plate 4 is then placed on top of the heat insulating materials 60a, 60b. The flashback suppression plate 4 is then attached to the second section 22 by screws, with the inner and outer holding rings 5a, 5b interposed between them. As a result, during combustion of the gas burner BN, the heat insulating materials 60a, 60b can suppress the conduction heat applied from the burner body 2 (specifically, the second portion 22) to the flashback suppression plate portion 4. In such a case, a packing having only a sealing function may be disposed at the joint between the first portion 21 and the second portion 22.

[0026] Furthermore, in the above embodiment, the heat dissipation portion is described as being composed of paint applied to the upper surface of the flashback suppression plate 4 located on the first chamber 21a side. However, the present invention is not limited to this, as long as it exhibits high heat dissipation properties in the fuel of the gas burner BN. Although not specifically illustrated or described, for example, a heat dissipation fin structure may be provided on the upper surface of the flashback suppression plate 4 located on the first chamber 21a side. Furthermore, in the above embodiment, the fuel gas supplied to the distribution chamber 21 is hydrogen gas without primary air mixed therein, which is ejected from the combustion plate 3 for diffusion combustion. However, the present invention can be widely applied to, for example, gas burners in which a mixture of fuel gas and primary air is supplied to the distribution chamber 21 and ejected from the combustion plate 3 for combustion. Furthermore, in the above embodiment, the cooking appliance is described as being a rice cooker HC. However, the present invention is not limited to this, and can be widely applied to other cooking appliances, such as gas stoves. [Explanation of symbols]

[0027] HC...rice cooker (heating cooker), BN...gas burner, 1...apparatus body, 2...burner body, 21...first part of burner body, 22...second part of burner body, 21...distribution chamber, 21a...first chamber of distribution chamber, 21b...second chamber of distribution chamber, 222a...inner holding part (holding part), 223a...outer holding part (holding part), 24...gas introduction passage, 3...combustion plate part, 4...flashback suppression plate part, 42...paint (heat dissipation part), 6a, 6b, 60a, 60b...insulating material.

Claims

1. A gas burner comprising: a burner body having a distribution chamber to which gas is supplied through a gas introduction passage; a combustion plate section covering an open surface of the burner body facing the distribution chamber; and a flashback suppression plate section disposed in the distribution chamber opposite the combustion plate section with a gap therebetween, wherein gas passing through the flashback suppression plate section is ejected from the combustion plate section and combusted, A gas burner characterized in that the burner body is constructed by joining a first part having the combustion plate portion and a second part having the flashback suppression plate portion, and an insulating material having a lower thermal conductivity than the second part is interposed at the joint between the first part and the second part.

2. A gas burner comprising: a burner body having a distribution chamber to which gas is supplied through a gas introduction passage; a combustion plate section covering an open surface of the burner body facing the distribution chamber; and a flashback suppression plate section disposed in the distribution chamber opposite the combustion plate section with a gap therebetween, wherein gas passing through the flashback suppression plate section is ejected from the combustion plate section and combusted, A gas burner characterized in that the burner body is provided with a holding portion that holds the flashback suppression plate portion within the distribution chamber, and an insulating material having a lower thermal conductivity than the burner body is interposed between the flashback suppression plate portion and the holding portion.

3. The distribution chamber is partitioned by the flashback suppression plate portion into a first chamber communicating with the gas introduction passage and a second chamber communicating with the combustion plate portion, the combined spatial volume of the first chamber, the second chamber, and the gas introduction passage is defined as a total volume, the spatial volume of the second chamber is defined as a clearance volume, and the spatial volume remaining after subtracting the clearance volume from the total volume is defined as a residual volume, 3. The gas burner according to claim 1, wherein the flashback suppression plate is disposed at a position where the gap volume is equal to or less than the residual volume.

4. 4. The gas burner according to claim 3, wherein a heat radiating portion is provided on a surface of the flashback suppression plate portion located on the first chamber side.

5. 3. A gas burner according to claim 1, wherein the gas supplied to the distribution chamber is fuel gas without primary air mixed therein, and the fuel gas is ejected from the combustion plate portion to cause diffusion combustion.

6. A cooking device comprising the gas burner according to claim 1 or 2.

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