Combustion equipment

Abstract

To provide a combustion device which can prevent a rear-end plate part from being excessively heated, and can further properly improve a heating effect by combustion.SOLUTION: A combustion space 20 is defined into a primary combustion chamber 21 having an input port 17 of a combustion matter on a side of a front-end plate part 15 by a first combustion promotion plate 30 having a large number of penetration holes 35, and a secondary combustion chamber 22 having an exhaust port 18 on a side of a rear-end plate part 16. The exhaust port 18 is provided at a ceiling plate part 11 of the secondary combustion chamber 22, and a second combustion promotion plate 40 which is arranged in a state of being extended downward from an inner face of the ceiling plate part 11 so as to define the exhaust port 18 and the secondary combustion chamber 22, and has a large number of penetration holes 45 is arranged. A lower end edge 47 of the second combustion promotion plate 40 is formed at a height having a necessary interval from an inner face of a bottom plate part 12, and a lower end part 46 of the second combustion promotion plate 40 is arranged while being formed into a shape which is bent to a side of the rear-end plate part 16 so as to approximate the inner face of the rear-end plate part 16.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a combustion device in which a combustion space formed by being surrounded by a top plate, a bottom plate, left and right side wall portions, a front end plate, and a rear end plate is arranged to extend downward from the inner surface of the top plate so that its lower edge is at a height that leaves a required distance from the inner surface of the bottom plate, and is partitioned by a first combustion promotion plate having a number of through holes into a primary combustion chamber having an inlet for combustion material on the front end plate side, and a secondary combustion chamber having an exhaust port on the rear end plate side. [Background technology]

[0002] The applicant has proposed a conventional combustion device in which half of the ceiling surface of the combustion chamber is constructed with a lid that can be opened and closed, providing an air supply port that also serves as an inlet for the combustion material, and the ceiling surface or side opposite the air supply port has an exhaust port to which a chimney is connected. A combustion promotion plate is suspended from the ceiling surface between the exhaust port and the air supply port, and a gap of 1 / 3 to 1 / 4 of the height of the combustion chamber is provided between the lower edge of the combustion promotion plate and the floor surface of the combustion chamber, thereby dividing the combustion chamber into a primary combustion chamber where the air supply port opens, and a secondary combustion chamber where the exhaust port opens, and the combustion promotion plate has a large number of through holes distributed throughout the plate that connect the primary combustion chamber and secondary combustion chamber (see Patent Document 1).

[0003] Furthermore, the applicant has proposed a conventional combustion device having a primary combustion chamber equipped with an inlet for the material to be combusted and an air supply inlet, and a secondary combustion chamber equipped with an exhaust port, with a combustion space separated by a combustion promotion plate which is fixed in a hanging state from the inner surface of the top plate, with its lower edge formed at a height that leaves a required distance from the inner surface of the bottom plate, and which has a number of through holes, wherein the exhaust port is provided in the top plate of the secondary combustion chamber, and at least one other combustion promotion plate which has a number of through holes equivalent to those of the combustion promotion plate is fixed in a hanging state from the inner surface of the top plate, with its lower edge formed at a height that leaves a required distance from the inner surface of the bottom plate, so as to divide the secondary combustion chamber across the opening of the exhaust port (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3066066 (Claim 1) [Patent Document 2] Patent No. 4785980 (Claim 1) Summary of the Invention [Problem to be solved by the invention]

[0005] The problems to be solved with regard to combustion devices are that, in a combustion device having a conventional combustion promotion plate, excessive combustion in the secondary combustion chamber is likely to occur, making it difficult to optimize the combustion balance between the primary and secondary combustion chambers, the rear end plate portion heats up excessively and becomes very hot, making it necessary to devise further improvements to the installation conditions, and an excessive chimney effect occurs, reducing fuel efficiency and making it difficult to further improve the heating effect.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a combustion device that can prevent the rear end plate portion from being excessively heated and more appropriately improve the heating effect of combustion. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has the following configuration. According to one aspect of the combustion device of the present invention, a combustion space defined by a top plate portion, a bottom plate portion, left and right sidewall portions, a front end plate portion, and a rear end plate portion is disposed in a state of extending downward from an inner surface of the top plate portion, and a lower end edge is disposed at a height that provides a required distance from an inner surface of the bottom plate portion. multiple a first combustion promotion plate having a through hole, which divides the combustion chamber into a primary combustion chamber having an inlet for combustion material on the side of the front end plate, and a secondary combustion chamber having an exhaust port on the side of the rear end plate, the exhaust port being provided on the top plate of the secondary combustion chamber and extending downward from the inner surface of the top plate so as to divide the exhaust port and the secondary combustion chamber; multiple The second combustion promotion plate has a through hole, and the lower edge of the second combustion promotion plate is provided at a height that provides a required distance from the inner surface of the bottom plate portion and has a lower end bent toward the rear end plate portion so as to be close to the inner surface of the rear end plate portion.

[0008] Furthermore, according to one embodiment of the combustion device of the present invention, the plate surface of the rear end plate portion, the plate surface of the first combustion promotion plate, and the plate surface of the second combustion promotion plate excluding the lower end portion are arranged in parallel.

[0009] According to one embodiment of the combustion device of the present invention, the first combustion promotion plate and the second combustion promotion plate are provided horizontally so that the portions of the first combustion promotion plate and the second combustion promotion plate excluding the lower end portions are extended substantially vertically downward. The above It can be characterized in that it is hung downward from the inner surface of the top plate portion.

[0010] Furthermore, according to one embodiment of the combustion device of the present invention, the second combustion promotion plate is extended lower than the first combustion promotion plate, and the lower end of the second combustion promotion plate is bent in an inclined shape.

[0011] According to one embodiment of the combustion device of the present invention, the first combustion promotion plate includes a frame-type combustion promotion plate portion having a cutout portion, and Frame type Promotion of combustion Shin board and a detachable combustion promotion plate portion that is detachably attached so as to overlap the cutout portion of the combustion promotion plate portion. Effect of the Invention

[0012] The combustion device of the present invention has a particularly advantageous effect of preventing the rear end plate portion from being excessively heated and more appropriately improving the heating effect of combustion. [Brief description of the drawings]

[0013] [Figure 1] 1 is a partially cutaway cross-sectional view showing an embodiment of a combustion device according to the present invention. [Diagram 2] FIG. 2 is a plan view of the embodiment of FIG. 1. [Diagram 3] FIG. 2 is a front view of the embodiment of FIG. 1 with a solid fuel inlet closed. [Figure 4] 2 is a front view of the embodiment of FIG. 1 with the solid fuel inlet open and the detachable combustion promotion plate portion removed from the frame-type combustion promotion plate portion of the first combustion promotion plate. FIG. [Diagram 5] FIG. 2 is a front view of a frame-type combustion promotion plate portion (part) of the first combustion promotion plate used in the embodiment of FIG. 1. [Figure 6] FIG. 2 is a front view of a detachable combustion promotion plate portion (part) of the first combustion promotion plate used in the embodiment of FIG. 1. [Figure 7] FIG. 7 is a plan view of the embodiment of FIG. 6. [Figure 8] 2 is a rear view of a second combustion promotion plate (part) used in the embodiment of FIG. 1. FIG. [Figure 9] FIG. 9 is a plan view of the embodiment of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] BEST MODE FOR CARRYING OUT THE DISCLOSURE Hereinafter, an embodiment of a combustion device according to the present invention will be described in detail with reference to the accompanying drawings (FIGS. 1 to 9).

[0015] In the basic form of the combustion device according to the present invention, a combustion space 20 is formed by being surrounded by a top plate 11, a bottom plate 12, left and right side walls 13, 14, a front end plate 15, and a rear end plate 16. The combustion space 20 is divided into a primary combustion chamber 21 having an inlet 17 for combustion material on the front end plate 15 side and a secondary combustion chamber 22 having an exhaust port 18 on the rear end plate 16 side by a first combustion promotion plate 30 which is arranged to extend downward from the inner surface of the top plate 11 and has a lower edge 37 at a height that provides a required distance from the inner surface of the bottom plate 12 and has a number of through holes 35. The front end plate 15 is a portion including an opening / closing door 51, which functions as a part of the front end plate 15 when closed.

[0016] It should be noted that the surrounding wall panel 10, which is composed of the top panel 11, bottom panel 12, and left and right side wall sections 13, 14, is not limited to a square tube shape as in the illustrated embodiment, and may of course be a cylinder shape, for example. In other words, when the surrounding wall panel 10 is cylindrical, the circumference can be substantially divided into four equal parts, with the upper arc of the circumference substantially corresponding to the top panel 11, the lower arc of the circumference substantially corresponding to the bottom panel 12, and the upper and lower intermediate parts substantially corresponding to the left and right side wall sections 13, 14.

[0017] In addition, in the combustion device of the present invention, an exhaust port 18 is provided in the top plate portion 11 of the secondary combustion chamber 22, and a second combustion promotion plate 40 having a number of through holes 45 is provided, the second combustion promotion plate 40 being extended downward from the inner surface (lower surface) of the top plate portion 11 so as to separate the exhaust port 18 and the secondary combustion chamber 22.

[0018] As shown in Figs. 2 to 4, the exhaust port 18 in this embodiment is located at the center of the secondary combustion chamber 22 in the left-right direction, and the chimney 50 is connected to the chimney connection tube portion 19 extending upward from this exhaust port 18 so as to extend substantially vertically upward from the top surface (the upper surface of the top plate portion 11). The secondary combustion chamber 22 in this embodiment has a width in the front-rear direction approximately equal to the diameter of the chimney 50, has a flat shape in the front-rear direction, and is smaller than the volume of the primary combustion chamber 21. The numerous through holes 35, 45 in this embodiment are basically the same diameter with the exception of a few, and are arranged in a state where they are uniformly distributed over the entire surface of the plate, but the present invention is not limited to this. They may be arranged in a staggered pattern, or their arrangement density or diameter may be changed to appropriately provide a gradient in the opening rate.

[0019] In addition, in this embodiment, the second combustion promotion plate 40 is arranged so as to cross the center of the circular exhaust port 18 from the secondary combustion chamber 22 side so as to divide the circular exhaust port 18 and the secondary combustion chamber 22 into front and rear halves, but the present invention is not limited to this, and the combustion promotion plate can be arranged appropriately. For example, in this embodiment, two combustion promotion plates 30, 40 are provided, but the number of combustion promotion plates can be increased. For example, when there are three combustion promotion plates, a third combustion promotion plate can be arranged between the first combustion promotion plate 30 and the second combustion promotion plate 40. By adding this third combustion promotion plate, the exhaust port 18 provided in the shape of a circular opening can be divided into three, and the secondary combustion chamber 22 can be divided into three. In other words, the number of combustion promotion plates is not limited to this embodiment, and may be appropriately selected and set according to the size of the exhaust port 18, etc. In addition, the combustion promotion plates 30, 40 in this embodiment are perforated partition plates formed by appropriately processing a flat metal plate, and are metal plates (steel plates or stainless steel plates in this embodiment) that promote combustion by becoming red-hot, but are not limited to this and, for example, ceramic plates can also be used.

[0020] The lower edge 47 of the second combustion promotion plate 40 is provided at a height that provides a required distance (a distance that allows the combustion air to flow appropriately) from the inner surface (inner bottom surface) of the bottom plate portion 12, and the lower end portion 46 of the second combustion promotion plate 40 is provided in a shape that is bent toward the rear end plate portion 16 so as to be close to the inner surface of the rear end plate portion 16. In this embodiment, as shown in FIG. 1, the second combustion promotion plate 40 is provided in a shape that is bent at the middle of the lower side so as to be in a V-shape. Note that the shape in which the lower end portion 46 of the second combustion promotion plate 40 is bent toward the rear end plate portion 16 is not limited to the shape of a single plate bent as in this embodiment, and it is of course possible to, for example, combine multiple members and form them into a substantially equivalent shape by fixing means such as welding.

[0021] According to the combustion device of the present invention, the rear end plate 16 is prevented from being excessively heated, and the heating effect by combustion can be improved more appropriately. That is, by providing a plurality of combustion promotion plates, namely the first combustion promotion plate 30 and the second combustion promotion plate 40, the secondary combustion chamber 22 can be heated more effectively by the favorable convection effect of the combustion air, as in the combustion device disclosed in Patent Document 2, and there is a straightening effect that makes the exhaust of the combustion air smooth, thereby improving the combustion performance. In addition, by providing the lower end 46 of the second combustion promotion plate 40 in a shape bent toward the rear end plate 16, the flow of the combustion air between the second combustion promotion plate 40 and the rear end plate 16 in the secondary combustion chamber 22 (the space 22b behind the secondary combustion chamber 22) can be restricted.

[0022] According to this, in the front space 22a of the secondary combustion chamber 22, the combustion air flows smoothly due to the chimney effect and the flow straightening effect as in the conventional case, and secondary combustion is promoted and the combustion efficiency can be improved. In the rear space 22b of the secondary combustion chamber 22, the flow of the combustion air is restricted by the lower end portion 46 of the second combustion promotion plate 40, and secondary combustion can be suppressed compared to the front space 22a of the secondary combustion chamber 22. Therefore, the rear end plate portion 16 can be prevented from being excessively heated, and the degree of freedom of installation conditions such as the installation position when installing this combustion device as a stove can be increased.

[0023] And, by suppressing the secondary combustion in the space 22b behind the secondary combustion chamber 22, excessive secondary combustion in the entire secondary combustion chamber 22 can be suppressed. Therefore, the combustion in the primary combustion chamber 21 is relatively activated, the combustion balance between the primary combustion chamber 21 and the secondary combustion chamber 22 can be more properly established, the efficiency of fuel and combustion can be improved, and the heating effect can be further improved. That is, according to the second combustion promotion plate 40 of the present invention, even when the combustion is relatively small and the flow of the combustion air is small, it can quickly glow red and promote the combustion, and when the combustion becomes relatively large, it acts to effectively suppress the flow of the combustion air and suppress the secondary combustion. Therefore, it is possible to moderately promote the combustion in the secondary combustion chamber 22 and moderately suppress the occurrence of excessive secondary combustion, and the combustion of the entire combustion device can be improved, and the heating effect can be further improved.

[0024] More specifically, as in this embodiment, the lower end edge 47 of the second combustion promotion plate 40 is provided so as to be close to the inner surface of the rear end plate portion 16 but not in contact with it, leaving a suitable distance (gap). That is, the distance between the lower end portion 46 of the second combustion promotion plate 40 and the inner surface (standing surface) of the rear end plate portion 16 in this embodiment can be provided to be, for example, about 5 to 25% of the distance between the part of the second combustion promotion plate 40 excluding the lower end portion 46 and the inner surface of the rear end plate portion 16. In this embodiment, as shown in FIG. 1, the gap between the lower end edge 47 of the second combustion promotion plate 40 and the inner surface of the rear end plate portion 16 has a width dimension (length distance) of about 15% of the distance between the part of the second combustion promotion plate 40 excluding the lower end portion 46 and the inner surface of the rear end plate portion 16, and the width dimension is about half the diameter dimension of the through holes 35, 45.

[0025] By providing the lower end 46 of the second combustion promotion plate 40 in this manner, it is possible to appropriately impede the flow of combustion air to the rear space 22b of the secondary combustion chamber 22, and to suppress secondary combustion in the rear space 22b. In addition, there is a gap between the lower end edge 47 of the second combustion promotion plate 40 and the inner surface of the rear end plate 16, and there is no direct heat conduction (heat transfer) from the second combustion promotion plate 40 to the rear end plate 16, so that overheating of the rear end plate 16 can be prevented. In other words, the plate surface of the second combustion promotion plate 40 on the side of the first combustion promotion plate 30 is heated sufficiently to act as a combustion promotion plate because secondary combustion is preferentially performed in the front space 22a, and it also acts as an overheating prevention plate for the rear end plate 16.

[0026] In this embodiment, the plate surface of the rear end plate portion 16, the plate surface of the first combustion promotion plate 30, and the plate surface of the second combustion promotion plate 40 excluding the lower end portion 46 are arranged in parallel. This allows a good balance between the shape of the combustion air passage formed between the respective plate surfaces and the directionality of the airflow due to the chimney effect of the combustion air, making the flow of the combustion air smooth and allowing efficient exhaust, thereby improving combustion efficiency.

[0027] In this embodiment, the first combustion promotion plate 30 and the second combustion promotion plate 40, except for the lower end 46, are hung downward from the inner surface of the horizontally installed top plate 11 so as to extend substantially vertically downward. This allows the direction of the combustion air passage formed between the respective plate surfaces to coincide with the direction of the ascending air current caused by the chimney effect of the combustion air, making the flow of the combustion air smooth and allowing efficient exhaust, thereby improving combustion efficiency. In this manner, in this embodiment, the plate surfaces are vertical surfaces in an upright state, so that ash can be prevented from accumulating.

[0028] In this embodiment, the second combustion promotion plate 40 extends further downward than the first combustion promotion plate 30, and the lower end 46 of the second combustion promotion plate 40 is bent in an inclined shape. This allows the second combustion promotion plate 40, which has the above-mentioned effects, to be constructed rationally and simply.

[0029] In the lower end 46 of the second combustion promotion plate 40 in this embodiment, the bending angle on the side facing the rear end plate 16 is set to be at least an obtuse angle. That is, the lower end edge 47 of the second combustion promotion plate 40 is located lower than the bent portion 41, and the lower end 46 is formed to be an inclined surface so as to approach the inner surface of the rear end plate 16. In this embodiment, the bending angle is set to 130 degrees. Since the bending angle is an obtuse angle in this way, ash can easily fall and ash accumulation can be prevented. Also, as shown in Figures 1, 8, 9, etc., 42 is a reinforcing plate portion, and three sheets are fixed by welding so that the lower end 46 of the second combustion promotion plate 40 maintains the bent shape and prevents deformation due to overheating.

[0030] In addition, the interval between the lower end edges 37, 47 of the plurality of combustion promotion plates 30, 40 and the inner surface (inner bottom surface) of the bottom plate portion 12 may be appropriately set so as to provide a gap through which the combustion air can flow appropriately. In this embodiment, as shown in FIG. 1, the interval between the lower end edge 37 of the first combustion promotion plate 30 and the inner surface of the bottom plate portion 12 is set to about 1 / 3 of the height of the combustion chamber, and the interval between the lower end edge 47 of the second combustion promotion plate 40 and the inner surface of the bottom plate portion 12 is set to about 1 / 4 of the height of the combustion chamber. The interval between the lower end edges 37, 47 and the inner surface of the bottom plate portion 12 is not limited to this embodiment, and can be appropriately and selectively set so as to generate an optimal flow of the combustion air in relation to various other conditions such as the size of the combustion chamber and the size of the numerous through holes 35, 45.

[0031] In addition, the aperture ratio of the numerous through holes 35, 45 provided in the combustion promotion plates 30, 40 in this embodiment is set to about 10%, but the present invention is not limited to this, and it is of course possible to appropriately and selectively set it in relation to various conditions so as to appropriately divide the space and to provide appropriate ventilation. The numerous through holes 35, 45 have a function of automatically correcting the balance of the flow of combustion air ventilating from the primary combustion chamber 21 to the secondary combustion chamber 22 when it becomes unbalanced, thereby realizing stable combustion.

[0032] Furthermore, in this embodiment, the first combustion promotion plate 30 is composed of a frame-type combustion promotion plate part 31 having a cutout part 32, and a detachable combustion promotion plate part 34 that is detachably attached so as to overlap the cutout part 32 of the frame-type combustion promotion plate part 31. The detachable combustion promotion plate part 34 in this embodiment has two hooks 38 (see Figs. 1 and 7) on its upper part, and two hook holes 33 (see Figs. 1 and 5) into which the two hooks 38 fit are provided on the upper part of the cutout part 32 of the frame-type combustion promotion plate part 31. The hooks 38 in this embodiment are formed by fixing bolts to the frame-type combustion promotion plate part 31, and are configured to be stably attached in a state in which they are in contact with the surface of the frame-type combustion promotion plate part 31 by their own weight when hung on the hook holes 33.

[0033] The cutout portion 32 in this embodiment is formed by cutting out a trapezoidal shape from the center of the frame-type combustion promotion plate portion 31 downward. Also, the lower edge portion 36 of the frame-type combustion promotion plate portion 31 is slightly bent backward. By bending this lower end portion 46, the rigidity can be increased and deformation due to heat can be suppressed, and the detachable combustion promotion plate portion 34 can be appropriately attached so as to overlap the frame-type combustion promotion plate portion 31, improving the ease of attachment.

[0034] According to this, the detachable combustion promotion plate part 34 can be easily and appropriately attached to the frame-type combustion promotion plate part 31 so as to fill the notch part, and the first combustion promotion plate 30 can be appropriately configured by integrally combining the detachable combustion promotion plate part 34 with the frame-type combustion promotion plate part 31. By configuring the first combustion promotion plate 30 in this way, the part of the first combustion promotion plate 30 that is most likely to be worn out by being burned when exposed to high temperatures can be easily replaced, the need for large-scale repairs can be reduced, and the plate can withstand long-term use, improving economy and reliability.

[0035] In this embodiment, an inlet 17 for materials to be burned is provided on the front end plate 15. Reference numeral 51 denotes an opening / closing door, which is formed so as to be able to open and close the inlet 17 for materials to be burned, and which is provided with a transparent window. Reference numeral 52 denotes an airtight member, which is arranged in a strip shape around the periphery of the inlet 17, and which is provided so as to prevent easy ventilation between the inlet 17 and the opening / closing door 51. Reference numeral 53 denotes a lid, which is provided so as to be able to open and close an air supply port 54. These two lids 53 and the air supply port 54 are arranged at the lower part of the front end plate 15.

[0036] Although the present invention has been described above in various preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. [Explanation of symbols]

[0037] 10 Surrounding wall panel 11 Top plate 12 Bottom plate part 13 Side wall 14 Side wall 15 Front end plate 16 Rear end plate 17 Inlet 18 Exhaust port 19 Chimney connection tube 20 Combustion space 21 Primary combustion chamber 22 Secondary combustion chamber 22a Front space 22b Rear space 30 First combustion promotion plate 31 Frame-type combustion promotion plate section 32 Notch 33 Hook hole 34 Desorption and combustion promotion plate section 35 Through hole 36 Lower edge 37 Bottom edge 38 Hook 40 Second Combustion Promotion Plate 41 Bending section 42 Reinforcement plate 45 Through hole 46 Lower end 47 Bottom edge 50 Chimney 51 Opening and closing doors 52 Airtight materials 53 Lid 54 Air supply port

Claims

1. A combustion device in which a combustion space is formed by being surrounded by a top plate, a bottom plate, left and right side walls, a front end plate, and a rear end plate, and the combustion space is partitioned into a primary combustion chamber having an inlet for combustion material on the front end plate side and a secondary combustion chamber having an exhaust port on the rear end plate side by a first combustion promotion plate which is disposed in a state of extending downward from the inner surface of the top plate so that its lower edge is at a height that leaves a required distance from the inner surface of the bottom plate and which has a plurality of through holes, The exhaust port is provided in the top plate portion of the secondary combustion chamber, and a second combustion promotion plate is disposed in a state of extending downward from an inner surface of the top plate portion so as to partition the exhaust port and the secondary combustion chamber, and the second combustion promotion plate has a plurality of through holes; A combustion device characterized in that the lower edge of the second combustion promotion plate is disposed at a height that leaves a required distance from the inner surface of the bottom plate portion, and the lower end of the second combustion promotion plate is bent toward the rear end plate portion so as to be close to the inner surface of the rear end plate portion.

2. 2. The combustion device according to claim 1, wherein the plate surface of the rear end plate portion, the plate surface of the first combustion promotion plate, and the plate surface of the second combustion promotion plate excluding the lower end portion are arranged parallel to each other.

3. 3. The combustion device according to claim 1, wherein the first combustion promotion plate and the second combustion promotion plate, except for the lower end portions, are hung downward from the lower surface of the horizontally disposed top plate portion so as to extend substantially vertically downward.

4. The combustion device according to any one of claims 1 to 3, characterized in that the second combustion promotion plate is extended further downward than the first combustion promotion plate, and the lower end of the second combustion promotion plate is bent into an inclined shape.

5. The combustion device according to any one of claims 1 to 4, characterized in that the first combustion promotion plate is composed of a frame-type combustion promotion plate portion having a cutout portion and a detachable combustion promotion plate portion that is detachable so as to overlap the cutout portion of the frame-type combustion promotion plate portion.

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