JP2002174410A - Internal port burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal port burner which can be manufactured at a low cost and in which temperature distribution is averaged. SOLUTION: The burner head of this internal port burner 1 is constituted of a pipe absorber 3, a burner body 5, and a mixing tube 7 connecting the absorber 3 and burner body 5 to each other. The inner tube 9 of the burner head is put in the burner body 5. The inner tube 9 is formed by superimposing a plurality of tip plates upon another. The tip plates are made of a sheet metal (a), have projecting sections which become spacers (b), and are vertically superimposed upon another in a ring-like shape (c). In addition, a gas passage (tip) 10 is formed in a spiral shape toward the inside of the burner (e).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a burner used for a gas stove or the like. In particular, it relates to an internal flame burner in which the flame is provided on the inner peripheral surface of the burner.

[0002]

2. Description of the Related Art FIGS. 8A and 8B show the structure of a conventional general internal burner burner. FIG. 8A is a longitudinal sectional view, and FIG. 8B is a perspective view of a burner head. A general internal burner burner 151 includes a pipe sucker 154 and a burner body 155.
And a mixing pipe 156 connecting the pipe sucker and burner body
And a burner head inner cylinder 150 that is fitted into the burner body 155. The nozzle 15 is provided in the pipe sucker 154.
2 are arranged. The burner head inner cylinder 150 has a cylindrical shape with a central opening. The burner head inner cylinder 150 has a slit-shaped flame port 15 extending downward from the upper end.
3 are formed side by side. Combustion gas is supplied from the nozzle 152 to the pipe suction device 154, and primary air is supplied to the pipe suction device 154 from around the nozzle 152, and both gases are mixed in the mixing pipe 156. At this time, the ratio of the primary air is 70 to 100%, which is higher than that of the Bunsen-type burner.

[0003] The mixed gas passes through the mixing pipe 156 and burns at the flame 153 of the inner cylinder 150 of the burner head.
The inside of the opening is blown in from the outlet inside 53. The flame ejected inward from each flame port 153 collides at the center of the opening and moves upward. Then, it hits the center of the bottom of a cooker such as a heated pot and spreads outward along the pot bottom to heat the entire pot bottom. For this reason, the contact time between the flame and the pot bottom is prolonged, and the thermal efficiency is improved. In addition, such an internal burner burner can reduce nitrogen oxides generated by combustion by 30 to 60% as compared with a conventional burner.
Further, the radiation heat is reduced by about 30% as compared with the conventional burner.

The above-described burner head inner cylinder 150 is manufactured by forming a slit-shaped flame port in a brass or stainless steel pipe by machining. To increase the burner input, increase the length of the flame outlet,
Or, it is dealt with by increasing the number of flame outlets.

[0005]

However, such a burner head requires a high manufacturing cost when cutting a slit-shaped flame. In addition, since the length and number of the flame outlets are changed according to the burner input, the production cost is relatively high.
Further, since the temperature of the crater is 500 to 600 ° C., the durability may not be sufficient in the case of brass.

[0006] Further, in the ordinary internal flame outlet burner, since the flame is concentrated at the center of the pot bottom as described above, the temperature at the center of the pot bottom may be locally high. For this reason, an adverse effect may occur depending on the type of dish.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an internal flame burner that can be manufactured at low cost and has an average temperature distribution.

[0008]

In order to solve the above-mentioned problems, an internal flame burner according to the present invention is an internal flame burner in which a flame is provided on the inner peripheral surface of a hollow cylindrical burner head, An internal flame burner, wherein the flame is formed by stacking a plurality of the following crater plates; (a) the crater plate is made of sheet metal; and (b) a convex portion or a gas passage serving as a spacer on the surface. (C) the crater plate is ring-shaped and stacked up and down; (d) the crater plate spacer is punched by attaching it to the crater plate body in a tongue shape On the crater plate body. A spacer portion is provided on the surface of the crater plate to form a slit-shaped space via the spacer when a plurality of crater plates are stacked. This space serves as a gas passage, and an outlet inside the gas passage serves as a crater from which a flame blows out. By stacking a plurality of crater plates, a necessary crater area can be secured. Further, since the crater plate can be manufactured by sheet metal processing, the processing time can be reduced and the cost can be reduced. Furthermore, the amount of material can be reduced.

In the present invention, the crater plates may be band-shaped and may be circumferentially stacked.
Further, the crater plate may be formed with irregularities by press working. Since the uneven portion is formed by pressing, it becomes easy to process the crater into various shapes and sizes by changing the thickness and shape of the uneven portion. For this reason,
A burner head having a crater area and a crater shape corresponding to various burner inputs can be easily manufactured. In addition, if the width (depth) of the crater plate is made wider, the depth of the flame of the crater can be made deeper, making it difficult for backfire to occur and reducing the sound of fire extinguishing. Further, the material can be reduced.

[0010] Further, the spacer of the crater plate is:
If the crater plate body is tongue-shaped and punched out, it is formed by folding back on the crater plate body,
It is easy to manufacture, and it is possible to make the convex portion serving as the spacer into a sharp shape. Further, it is easy to form convex portions having various shapes.

In the present invention, it is preferable that the gas passage is formed in a spiral shape inward to the burner. Since the flame is swirled out from the crater, the temperature distribution at the bottom of the pot is averaged. Furthermore, since the flame length is shortened, Goku can be installed at a lower position,
Thermal efficiency is improved. In addition, the mixed gas flowing through the mixing tube easily flows in a spiral shape, and the flow of the combustion gas becomes smooth.

[0012] In the present invention, the crater plate comprises:
It is preferably formed in the shape of a truncated cone inclined obliquely upward toward the center of the burner head. With this shape, the gas passage of the flame outlet faces obliquely upward. For this reason,
The flame spreads outward on the burner head from diagonally above, and it is possible to prevent concentrated heating of the central part of the bottom of the pot. Further, when the burner of this aspect is used as the outer ring burner of the inner / outer two-stage burner, it is possible to prevent the flame of the outer ring burner from colliding with the flame of the inner ring burner and to prevent the flame from entering the inner ring burner. .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a structure of an internal flame port burner including a burner head according to an embodiment of the present invention,
(A) is a plan view and (B) is a longitudinal sectional view. 2A and 2B are views for explaining the structure of a burner head inner cylinder of the internal flame port burner of FIG. 1, wherein FIG. 2A is a longitudinal sectional view, FIG. 2B is a plan view of a crater plate, and FIG. It is sectional drawing.
First, the structure of the internal flame port burner will be described with reference to FIG. The internal burner burner 1 includes a pipe suction device 3, a burner body 5, and a mixing pipe 7 connecting the pipe suction device and the burner body. A nozzle 4 is arranged in the pipe sucker 3. A burner head inner cylinder 9 shown in FIG. 2 is fitted in the burner body 5. A number of craters 10 are formed in the burner head inner cylinder 9.

A combustion gas (city gas, propane gas, etc.) is supplied to the nozzle 4 from a gas supply pipe (not shown). A damper (not shown) is provided around the nozzle 4 of the pipe sucker 3, from which primary air is supplied. The supplied combustion gas and primary air are mixed in the mixing pipe 7. This mixed gas is supplied to the crater 10 of the burner body 5.
And is mixed with the secondary air and burned, and a flame is blown out from the crater 10.

The burner head inner cylinder 9 will be described with reference to FIG. The burner head inner cylinder 9 includes a cover 11
, A base 13 and a plurality of crater plates 15. The crater plates 15 are sandwiched between the cover 11 and the base 13 in a stacked state, and are fixed with screws 17.

The cover 11 is made of cast iron (one example) and has an annular shape having an opening 19 in the center. The upper surface of the cover 11 is slightly inclined outward and downward, and the lower surface is planar. An annular groove 21 is formed on the lower surface along the outer periphery, and the groove 21 is fitted in the burner body 5, and the burner head inner cylinder 9 is placed. On the lower surface, four screw holes are formed at equal intervals. As an example, cover 1
1 has an outer diameter of 94 mm and the opening 19 has a diameter of 42 mm. The base 13 is made of stainless steel (one example) and is an annular plate having an opening having the same diameter as the opening 19 of the cover 11. Four screw holes are formed in the base 13 at equal intervals.

The crater plate 15 has a flat annular plate body 23 as shown in FIG. 2 (B). The plate body 23 is made of stainless steel (one example) and is manufactured by sheet metal processing. In this example, eight substantially rhombic spacers 25 are arranged at equal intervals on the lower surface (or upper surface) of the plate body 23 and are joined by spot welding. The spacer 25 is also made of stainless steel and is manufactured by sheet metal processing.

All the spacers 25 are positioned so that the shape between adjacent spacers is oriented in the same diagonal direction (spiral shape) with respect to the radial direction of the plate body 23. As will be described later, the space between the adjacent spacers 25 becomes a gas passage and forms a crater. By making this shape oblique, the flame is spouted from each crater into the burner in a spiral shape.
Of the spacers, the spacers 25 (four in this example), which are arranged every other half, have substantially equal lengths of the outer peripheral edge and the inner peripheral edge. Along the inner periphery. Further, in every other spacer 25a (four in this example), the outer peripheral edge is longer than the inner peripheral edge. A semicircular concave portion 27 is cut from the outer peripheral edge of the plate body 23 at a portion where the long outer peripheral spacer 25 a is joined. The screw 17 is positioned in the recess 27.

As an example, the outer diameter of the plate body 23 is 6.2 mm, the inner diameter is 4.8 mm, and the thickness is 1 mm.
The length of the inner peripheral edge of the spacer 25 is 6 mm, the length of the outer peripheral edge is 6 mm, the length of the expanded outer peripheral edge is 10 mm, and the thickness is 1 mm.

Referring to FIG. 2A, the structure of the burner head inner cylinder will be further described. Tinder plate 15
In this example, 16 pieces are stacked with the surface to which the spacer 25 is joined facing downward. At this time, the crater plate 15 is overlapped so that the position of the concave portion 27 cut from the outer peripheral edge coincides with the vertical direction. The stacked crater plates 15 are sandwiched between the cover 11 and the base 13 with the position of the concave portion 27 and the position of the screw holes of the cover 11 and the base 13 matched, and are fixed with the screws 17. In this state, a space 29 with a thickness of 1 mm is formed between the stacked crater plates 15 with spacers 25 interposed therebetween. The space 29 is located at the same position in the height direction of the inner cylinder 9 of the burner head, and in this example, forms eight craters 31 (see FIG. 2B). The crater 31 faces the same oblique direction to the radial direction of the burner head inner cylinder 9.

In the internal burner burner 1 using the burner head inner cylinder 9, the flame blows out in a spiral inward direction (indicated by an arrow in the drawing) along the direction of the crater 31. Therefore, the flame can be spirally rotated, and the combustibility is improved. Although the number of spacers is eight in this example, the size of the burner head also changes depending on the size of the input of the burner, and the number and size of the spacers can be changed accordingly. Similarly, the width of the crater plate can be varied. Since all crater plates of the burner head of the present invention are manufactured by sheet metal processing,
Such processing can be easily performed.

FIGS. 3, 4 and 5 are views for explaining the shapes of various crater plates according to other embodiments of the present invention, wherein (A) is a plan view and (B) is a plan view. It is a front view. These crater plates are stacked in the same manner as the crater plate of FIG. 2 (B), sandwiched between a cover and a base, and fixed with screws for application.

FIG. 3 shows a crater plate formed by folding a spacer. The crater plate 45 in this example is
The spacer 55 is provided integrally with the plate body 53. That is, at the stage of the punching of the plate material, eight tongue-shaped protrusions extend outward from the outer peripheral edge at a position corresponding to the spacer portion of the plate body 53 in this example. In the next step of the press working, these protruding pieces are turned inward at the outer peripheral edge of the plate main body 53 and overlapped on one surface of the plate main body 53 to form the spacer 55. As in the crater plate of FIG. 2B, the shape of the protruding piece is a shape in which the space between the adjacent spacers 55 is spiral, and the tip is substantially along the inner peripheral edge of the plate body 53. Further, a through-hole is formed in a portion of the alternate protruding piece that extends over the outer peripheral edge of the plate body 53. When the protruding piece is folded, the through hole is folded substantially at the center to form a semicircular recess 57. The recess 57 is for screw positioning. In the crater plate 45 of this example, since the spacer 55 is formed integrally with the plate body 53, the manufacturing process is simplified.

FIG. 4 shows a crater plate produced by bending. The crater plate 65 of this example has a spacer portion formed on the plate body 73 by bending. That is, in this example, four protrusions 74 are formed at equal intervals along the inner peripheral edge of the flat plate-shaped plate body 73 by bending. All protrusions 74
Have the same width and length and are formed in a spiral shape.
The height of the projection 74 is about 1 mm, and this portion acts as a spacer, and four craters are formed between adjacent spacers. Four semicircular recesses 77 are formed at equal intervals along the outer peripheral edge of the plate body 73. This recess 77 is for screw positioning. The crater plate 65 of this example has a simple structure and a simple manufacturing process.
The material may be small.

FIG. 5 shows a crater plate having a plate body having an inclined shape. The crater plate 85 in this example is
The plate body 93 has a truncated cone shape formed in a truncated cone shape that is inclined obliquely upward toward the center. The angle of the plate body 93 with respect to the horizontal plane is about 10 to 20 °. The spacers 95 are joined to the upper surface of the plate body 93 by welding at regular intervals, similarly to the crater plate of FIG. A semicircular recess 97 is formed in the outer peripheral edge of every other spacer 95 and the plate body 93. The recess 97 is for screw positioning. In the crater plate 85 of this example, since the crater faces diagonally upward,
The flame rises while rotating in a spiral. For this reason, especially when used as a burner for the outer ring in a double stove described later, the flame of the outer ring burner is prevented from colliding with the flame from the burner for the inner ring.

FIGS. 6A and 6B are views for explaining the structure of a burner head inner cylinder according to another embodiment of the present invention, wherein FIG. 6A is a longitudinal sectional view, FIG. 6B is a transverse sectional view, and FIG. It is a perspective view of a crater plate. The burner head inner cylinder 99 of this example includes a cover 101, a base 103, and a plurality of crater plates 1.
05. The crater plate 105 is radially arranged in the circumferential direction of the inner cylinder 99 of the burner head, and
01 and the base 103 are fixed with screws 107.

As shown in FIG. 6C, the crater plate 105 is obtained by bending a rectangular plate body 113 in the longitudinal direction so that its cross section has a U-shape. The plate body 113 is made of stainless steel and is bent by bending. One of the side surfaces of the bent plate body 113 has an upper part on one side and a lower part on the other side.
15a and 115b are formed by bending. The protrusion 115 acts as a spacer between the adjacent plate bodies 105. The base 103 has a flat plate ring shape, and has side walls rising upward from the inner peripheral edge and the outer peripheral edge.

The plate body 105 is positioned so that the opened side faces outward, the lower end is fitted between the side walls of the base 103, and is arranged radially in the circumferential direction of the base 103. At this time, the upper and lower protrusions 115 on both sides of the plate body 105 are located in the same direction. In this example, the lower protruding portion 115b faces clockwise, and the upper protruding portion 115a faces counterclockwise. A vertically extending slit-like space 119 is formed between the plate bodies 105 via these projections 115. This space 1
19 is a gas passage, and an inner outlet of the passage acts as a crater. The crater plate 105 is sandwiched between the cover 101 and the base 103, and both are fixed with screws 107. At this time, the screw 107 passes through the U-shaped inner space of the plate body 105.

The burner head having this shape can be expected to have an advantage that a product of the same shape can be continuously press-worked and the cost can be reduced.

FIGS. 7A and 7B are views for explaining the structure of a burner according to another embodiment of the present invention. FIG. 7A is a plan view of the burner, and FIG. It is sectional drawing. This gas stove 120 is inside and outside 2
The burner is a step burner and includes an inner ring burner 121 and an outer ring burner 123.

The inner ring burner 121 has substantially the same configuration as that of the burner shown in FIG. 2, and includes a pipe suction unit 129, a burner body 131, and a mixing pipe 133 connecting the pipe suction unit and the burner body. The burner head 131 shown in FIG. 1 is mounted on the burner body 131. The cover 135 of the burner body 125 in this example is different from the cover of the burner body in FIG. 1 in that a cylindrical side wall 137 that rises upward from the edge of the central opening is formed. In the inner ring burner of the inner and outer two-stage burner, the position of the crater is lowered so that the burner body is not heated by the flame of the outer ring burner. For this reason, the distance from the bottom of the pot is increased, the flame easily comes into contact with the air, and the NOx value tends to increase. Therefore, by providing such a high side wall 137, the distance to the pot bottom is shortened to lower the NOx value. The diameter of the burner body 125 is about 48 mm.

The outer ring burner 123 includes a pipe sucker 139,
It is composed of a burner body 141 and a mixing pipe 143 connecting the pipe suction device and the burner body. The burner body 141 is a burner body 131 of the inner ring burner 121.
Larger diameter. The burner head 127 is mounted on the burner body 141. The burner head 127 has a plate body formed in a truncated cone shape as shown in FIG. The diameter of the burner head 127 is about 173 mm. A mixing plate 142 is provided at a communicating portion between the mixing pipe 143 and the burner body 141. The mixing plate is provided to further extend the mixing pipe to improve the mixing property between the combustion gas and air and the air suction performance, thereby improving the combustibility.

The inner ring burner 121 and the outer ring burner 123
Is set on the pedestal 140. At this time, the burner body 131 of the inner ring burner 121 is
In the central opening of the burner body 141, the two burner bodies 131 and 141 are arranged so as to be substantially concentric. Furthermore, the tube suckers 129, 139 of both burners are oriented in the same direction. A nozzle 140 is arranged in both pipe suction devices 129 and 139. The nozzle 140 is supplied with a combustion gas (city gas, propane gas, etc.) from a gas supply pipe. A damper (not shown) is provided around the nozzles of the two pipe suction devices, and primary air is supplied from the damper. The supplied combustion gas and primary air are mixed in both mixing tubes. This mixed gas is ignited at the flame outlets of both burner heads, and further mixed with secondary air and burned,
Flames erupt from the flame outlet.

Since the crater of the inner ring burner 121 is formed in a spiral shape, the flame is spouted inward in a spiral shape. Further, in the outer ring burner 123, since the crater plate is inclined upward toward the center, the flame is spouted obliquely upward and inward. Therefore, the flame spouted from the inner ring burner 121 hits near the center of the pot bottom and heats the same part, and the flame spouted from the outer ring burner 123 spreads outward on the burner head from diagonally above, and the central part of the pot bottom. Heat around. Further, in the case of a normal inner / outer two-stage burner, when a pot or the like is placed, an inner pressure is applied to the inner ring burner, and the combustion gas may flow backward through the inner ring burner. If the outer ring burner of this example is used, the flame of the outer ring burner is blown obliquely upward, so that such backflow can be prevented.

As shown in FIG. 7B, the outer ring burner 1
A juice tray 145 is arranged on 23 around the burner head 127 of the burner. In addition, a saucer 145
At the top is Gotoku 147. In this example, Gotoku 1
The distance from the upper surface of 47 (the bottom surface of the pot) to the upper surface of the burner head 127 of the outer ring burner 123 is 60 mm, and the distance from the upper surface of the burner head 125 of the inner ring burner 121 is 85 mm.

[0036]

As is apparent from the above description, according to the present invention, it is possible to provide an internal flame burner that can be manufactured at low cost and has an averaged temperature distribution.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a structure of an internal flame port burner including a burner head according to an embodiment of the present invention;
(A) is a plan view and (B) is a longitudinal sectional view.

FIGS. 2A and 2B are views for explaining the structure of a burner head inner cylinder of the internal flame port burner of FIG. 1, wherein FIG. 2A is a longitudinal sectional view and FIG.
2 is a plan view of the crater plate, and FIG. 3C is a cross-sectional view of the crater plate.

3A and 3B are diagrams illustrating various shapes of a crater plate according to another embodiment of the present invention, wherein FIG.
(B) is a front view.

4A and 4B are diagrams illustrating various shapes of a crater plate according to another embodiment of the present invention, wherein FIG.
(B) is a front view.

5A and 5B are diagrams for explaining various shapes of a crater plate according to another embodiment of the present invention, wherein FIG.
(B) is a front view.

FIG. 6 is a view for explaining the structure of a burner head inner cylinder according to another embodiment of the present invention, where (A) is a longitudinal sectional view,
(B) is a cross-sectional view, and (C) is a perspective view of a crater plate.

FIG. 7 is a view for explaining a structure of a burner according to another embodiment of the present invention, wherein (A) is a plan view of the burner,
(B) is a sectional view of a main part of a gas stove equipped with the burner.

8A and 8B are views showing a structure of a conventional general internal flame port burner, wherein FIG. 8A is a longitudinal sectional view and FIG. 8B is a perspective view of a burner head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal flame port burner 3 Pipe suction unit 5 Burner body 7 Mixing pipe 9, 99 Burner head inner cylinder 10 Crate 11, 101 Cover 13, 103 Base 15, 45, 65, 85, 105 Crate plate 17, 107 Screw 19 Opening 21 Grooves 23, 53, 7
3, 93 Plate body 25, 55, 95 Spacer 27, 57, 7
7, 97 recess 29, 119 space 31 crater 74 protrusion 99 burner head inner cylinder 101 cover 103 base 115 projection 120 internal flame burner 121 inner ring burner 123 outer ring burner 125 burner head 127 burner head 129 pipe absorber 131 burner body 133 mixing pipe 135 Cover 137 Side wall 139 Pipe suction device 140 Base 141 Burner body 142 Mixing plate 143 Mixing tube 145 Juice tray 147 Gotoku

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 591232233 Setagaya Manufacturing Co., Ltd. 4-2-19-1 Nozawa, Setagaya-ku, Tokyo (72) Inventor Nobuo Otake 1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd. (72) Inventor Toshinari Momose 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Osaka Gas Co., Ltd. (72) Inventor Toshimichi Ohara 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Co., Ltd. (72) Inventor Masafumi Matsubara 19-18 Sakuradacho, Atsuta-ku, Nagoya, Aichi Prefecture Inside Toho Gas Co., Ltd. (72) Inventor Hideyuki Sugihara 4-2-119 Nozawa, Setagaya-ku, Tokyo (72) Inventor Yasuo Ishikawa 4-2-19-1 Nozawa, Setagaya-ku, Tokyo F-term (reference) in Setagaya Works 3K017 AA10 AB02 AB07 AB09 AD11

Claims (5)

[Claims] 1. An internal flame burner in which a burner is provided on an inner peripheral surface of a hollow cylindrical burner head, wherein the flame is formed by stacking a plurality of the following crater plates. (A) The crater plate is made of sheet metal; (b) a convex portion serving as a spacer or a concave portion serving as a gas passage is formed on the surface; (c) the crater plate is ring-shaped and (D) The crater plate spacer is formed by folding the crater plate main body in a tongue shape and punching it out on the crater plate main body. 2. An internal flame port burner having a hollow cylindrical burner head provided with a flame port on an inner peripheral surface thereof, wherein the flame port is formed by stacking a plurality of the following crater plates. (A) The crater plate is made of sheet metal; (b) a convex portion serving as a spacer or a concave portion serving as a gas passage is formed on the surface; (c) the crater plate is ring-shaped and (E) the gas passage is formed spirally inward of the burner. 3. An internal flame port burner in which a flame port is provided on an inner peripheral surface of a hollow cylindrical burner head, wherein the flame port is formed by stacking a plurality of the following crater plates. (A) The crater plate is made of sheet metal; (b) a convex portion serving as a spacer or a concave portion serving as a gas passage is formed on the surface; (c) the crater plate is ring-shaped and (F) The crater plate is formed in the shape of a truncated cone inclined obliquely upward toward the center of the burner head. 4. An internal flame port burner in which a flame port is provided on an inner peripheral surface of a hollow cylindrical burner head, wherein the flame port is formed by stacking a plurality of the following crater plates. (A) The crater plate is made of sheet metal; (b) a convex portion serving as a spacer or a concave portion serving as a gas passage is formed on the surface; (c) the crater plate is band-shaped and has a circumference Are stacked in the direction. 5. An internal burner burner comprising an inner race burner and an outer race burner, wherein the inner race burner and the outer race burner are provided with a flame opening on an inner peripheral surface of a hollow cylindrical burner head. An internal flame port burner characterized by stacking a plurality of the following crater plates; (a) the crater plate is made of sheet metal; (b) a convex portion serving as a spacer or a concave portion serving as a gas passage is formed on the surface. (C) the crater plates are ring-shaped and are stacked up and down; (f) the crater plates of the outer ring burner are formed in a truncated conical shape inclined obliquely upward toward the center of the burner head. Have been.