Combustion device

Abstract

This invention provides a combustion device. This suction combustion type combustion device can suppress the deterioration of the combustion state, reduce thermal efficiency, and promote cooling of the outer wall of the combustion chamber and the heat insulation plate to prevent overheating. A heat insulation plate (12) is provided on the inner surface of the combustion chamber (1), which has a combustion chamber (3) housing a burner (4). A combustion fan is positioned downstream of the flow direction of the combustion exhaust to form a suction combustion type combustion device. The heat insulation plate (12) abuts against a portion of the outer wall (6) of the combustion chamber (1), forming a closed space (15) between the outer wall (6) of the combustion chamber (1) and the heat insulation plate (12). An air inlet hole (17) for introducing air is provided in the closed space (15). An outlet opening (18) is provided to allow air from the closed space (15) to flow out into the combustion chamber (3).

Description

Technical Field

[0001] The present invention relates to a suction combustion type combustion device in which the combustion fan for supplying combustion air to the burner is arranged downstream of the flow direction of the combustion exhaust generated by the burner. Background Technology

[0002] Conventionally, a combustion device is known (for example, see Patent Document 1) in which multiple burners are arranged inside a rectangular cylindrical combustion chamber, the burners being arranged along their length in one direction and orthogonal to that length direction, and a heat insulation plate is provided on the inner surface of the outer wall of the combustion chamber with a gap between the heat insulation plate and the inner surface. In this combustion device, a combustion fan for supplying combustion air to the burners is positioned upstream of the burners.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Application No. 2016-125684 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, in addition to combustion devices where the combustion fan is located on the upstream side of the burner, there are also combustion devices with the combustion fan located on the downstream side of the burner, which are called suction combustion devices.

[0008] When the combustion fan is positioned downstream of the combustion chamber, negative pressure is applied evenly throughout the entire combustion chamber. As a result, cooling air cannot flow towards the outer wall and heat insulation of the combustion chamber, leading to insufficient cooling and overheating of these components.

[0009] Therefore, increasing the speed of the combustion fan to increase the overall air volume is considered. However, due to the excessive supply of combustion air and the large amount of air flow, the combustion state may deteriorate and the thermal efficiency may decrease.

[0010] In view of the above problems, the object of the present invention is to provide a combustion device in a suction combustion type combustion device that can suppress the deterioration of the combustion state and the reduction of thermal efficiency, and can promote the cooling of the outer wall and heat insulation plate of the combustion chamber to prevent overheating.

[0011] Methods for solving problems

[0012] To achieve the above objectives, the technical content of the suction-type combustion device of the present invention is as follows. In this combustion device, a heat insulation plate is provided on the inner surface of a combustion chamber having a combustion chamber, and a burner is housed inside the combustion chamber. A combustion fan for supplying combustion air to the burner is positioned downstream of the flow direction of the combustion exhaust generated by the burner. The combustion device is characterized by comprising:

[0013] An enclosed space is formed around a portion of the outer wall of the combustion chamber by means of the heat insulation plate; the enclosed space is formed in the portion of the outer wall of the combustion chamber between the heat insulation plate and the outer wall of the combustion chamber.

[0014] An air inlet is formed on the outer wall of the combustion chamber at the location where the enclosed space is formed, and allows air to be introduced into the enclosed space; and,

[0015] An outlet opening is formed on the heat insulation plate at the location where the enclosed space is formed, and allows air from the enclosed space to flow out to the combustion chamber.

[0016] According to the above structure, the enclosed space formed by a portion of the outer wall of the combustion chamber and the heat insulation plate allows fresh external air to pass through the interior of the enclosed space via air inlet holes and outlet openings. This external air is then used to cool the outer wall of the combustion chamber and the heat insulation plate at the location of the enclosed space.

[0017] A portion of the outer wall of the combustion chamber used to form the enclosed space can be positioned as desired. Furthermore, the enclosed space is sealed off by the contact between the outer wall of the combustion chamber and the heat insulation plate. External air, intended to achieve a high cooling effect, is introduced into this enclosed space for cooling.

[0018] Therefore, by providing enclosed spaces in areas of highest temperature, such as the heat insulation panels and the outer walls of the combustion chamber, it is possible to efficiently cool these areas with a smaller amount of external air. Thus, by introducing only a small (necessary but minimal) amount of external air to concentrate cooling on the areas most in need of cooling, the deterioration of combustion conditions and reduction in thermal efficiency caused by the introduction of external air can be minimized.

[0019] Furthermore, the combustion device of the present invention is a suction combustion device with the combustion fan located downstream of the burner, thus creating a negative pressure inside the combustion chamber during combustion. This prevents combustion exhaust from leaking out of the combustion chamber through the air inlet. Moreover, by setting the size and number of the air inlets, the desired amount of air can be accurately introduced.

[0020] As described above, according to the present invention, the effects of deterioration of combustion state and reduction of thermal efficiency can be minimized, and sufficient cooling can be achieved efficiently.

[0021] It should be noted that, as a specific method of the enclosed space, an example can be given by making the heat insulation plate corresponding to the aforementioned part of the area bulge towards the combustion chamber, and making the outer wall of the combustion chamber abut against the periphery of the bulging part.

[0022] As a more preferred embodiment, the combustion device of the present invention is characterized in that the enclosed space is formed inside the first protrusion by a first protrusion bulging outward from a portion of the outer wall of the combustion chamber and a heat insulation plate abutting against the periphery of the first protrusion of the outer wall of the combustion chamber.

[0023] The first protrusion forming the enclosed space bulges outward from the combustion chamber. Therefore, the enclosed space is formed at a position away from the flame of the burner, and is not easily affected by the heat of the burner flame.

[0024] Furthermore, the combustion device of the present invention is characterized in that the heat insulation plate has a second protrusion at a position corresponding to the first protrusion, which bulges into the interior of the enclosed space.

[0025] The second protrusion is bulging outwards into the enclosed space, thereby keeping the heat insulation plate at the location of the enclosed space away from the burner flame and further preventing the heat insulation plate from overheating.

[0026] Furthermore, the combustion device of the present invention is characterized in that the outflow opening is formed at a position downstream of the burner and downstream of the air inlet.

[0027] Therefore, the flow of external air entering the enclosed space from the air inlet and flowing to the combustion chamber from the outlet opening can follow the flow of combustion exhaust, thereby efficiently cooling the outer wall of the combustion chamber and the heat insulation plate through the smooth flow of external air.

[0028] Furthermore, the combustion device of the present invention is characterized in that the heat insulation plate has an inclined plate that is inclined from the downstream end of the outflow opening toward the upstream side of the enclosed space and toward the outer wall of the combustion chamber.

[0029] External air entering the enclosed space through the air inlet and flowing towards the outlet opening is guided by the inclined vanes and flows into the combustion chamber from the outlet opening. The inclined vanes are tilted towards the upstream side within the enclosed space and towards the outer wall of the combustion chamber. As a result, the external air guided into the combustion chamber by the inclined vanes contacts the combustion exhaust flowing within the combustion chamber at an acute angle, and after entering the combustion chamber, it also flows along the heat shield. This also cools the heat shield in the downstream area of ​​the outlet opening.

[0030] Furthermore, the combustion device of the present invention is characterized in that it also includes a cover wall panel, which is continuously disposed with the heat insulation plate and covers the inner surface of the combustion chamber at a position upstream of the enclosed space and downstream of the burner.

[0031] In a suction-type combustion device, the combustion air is drawn in by the fuel gas ejected from the burner's flame nozzle, which easily generates turbulence caused by eddies. Sometimes, the combustion exhaust can come into contact with the outer wall of the combustion chamber downstream of the burner, causing the outer wall of the combustion chamber to overheat.

[0032] According to the present invention, by providing a covering wall panel, even if turbulent flow of combustion exhaust occurs, it is possible to prevent combustion air from contacting the outer wall of the combustion chamber, thereby suppressing the temperature rise of the outer wall of the combustion chamber. Attached Figure Description

[0033] Figure 1 This is an illustrative perspective view showing the main parts of a combustion device according to an embodiment of the present invention.

[0034] Figure 2 This is an illustrative cross-sectional view of the combustion chamber and heat exchange chamber in the combustion apparatus of this embodiment.

[0035] Figure 3 This is an illustrative three-dimensional diagram showing the heat insulation panel.

[0036] Figure 4 It is an illustrative sectional view showing the enclosed space.

[0037] Figure 5 This is an illustrative perspective view showing a modified example of the second convex portion.

[0038] Symbol Explanation

[0039] 1…combustion box, 3…combustion chamber, 4…burner, 6…outer wall (outer wall of the first combustion section), 12…heat insulation plate, 14…first protrusion, 15…enclosed space section, 17…air inlet hole, 18…outlet opening, 16…second protrusion, 19…inclined plate, 20…covering wall panel. Detailed Implementation

[0040] An embodiment of the present invention will be described with reference to the accompanying drawings. The combustion device in this embodiment is used as a heat source for a water heater, such as... Figure 1 As shown, the combustion device includes a combustion chamber 1 and a heat exchange chamber 2.

[0041] like Figure 2 As shown, a combustion chamber 3 is formed inside the combustion box 1. Multiple burners 4, each having a flame opening 4a at its upper end, are disposed inside the combustion chamber 3. Each burner 4 is formed into an elongated shape that is equal to its length in one direction (the front-to-back direction in this embodiment), and these burners 4 are arranged in a direction orthogonal to the length direction (the transverse direction in this embodiment).

[0042] The heat exchanger 5, which is used to supply hot water and serves as the object to be heated, is housed inside the heat exchange box 2. A combustion fan (not shown) is connected to the upper part of the heat exchange box 2 (downstream of the flow direction of the combustion exhaust).

[0043] The combustion fan forces the exhaust gas generated by the combustion of the burner 4 to flow in the discharge direction. At this time, a negative pressure is formed in the combustion chamber 3, and combustion air is drawn in from the outside into the air supply chamber (not shown) formed below the burner 4.

[0044] Since the combustion air is supplied by suction, the combustion device in this embodiment is called a suction combustion type combustion device.

[0045] A gap is formed between each adjacent burner 4 to allow air to pass through. Air below each burner 4 is supplied to the burner 4 as secondary air as it flows through these gaps toward the combustion chamber 3.

[0046] The combustion chamber 1 is generally rectangular cylindrical in shape and has a pair of first combustion section outer walls 6 located on the front and rear sides and facing each other in the upright state, and a pair of second combustion section outer walls 7 located on the left and right sides and facing each other in the upright state. The two first combustion section outer walls 6 are located on the front and rear ends of each burner 4, and the two second combustion section outer walls 7 are located on the left and right sides of each burner 4.

[0047] like Figure 1 and Figure 2 As shown, the base end of the ignition electrode 8 that ignites the burner 4 and the base end of the flame rod 9 that detects the combustion of the burner 4 are supported by the outer wall 6 of the first combustion section.

[0048] The heat exchange box 2 is formed into a generally square cylindrical shape that is continuous with the combustion box 1, and includes: a first heat exchange section outer wall 10 that is integrally formed with the upper edge of the first combustion section outer wall 6; and a second heat exchange section outer wall 11 that is connected to the upper edge of the second combustion section outer wall 7. The front and rear ends of the second heat exchange section outer wall 11 are connected to the left and right ends of the first heat exchange section outer wall 10 to form a cylindrical shape.

[0049] like Figure 2 and Figure 3 As shown, a heat insulation plate 12 covering the inner surface of the outer wall 6 of the first combustion section and a cover wall plate 13 continuous with the heat insulation plate 12 are provided in the combustion chamber 3.

[0050] A first protrusion 14, bulging outwards, is formed in a portion of the outer wall 6 of the first combustion section of the combustion chamber 1. The first protrusion 14 is located above the burner 4 (downstream of the burner 4), and the combustion chamber 3 side of the first protrusion 14 is covered by a heat insulation plate 12. (As...) Figure 3 As shown, the first protrusion 14 is formed into a roughly quadrilateral shape.

[0051] The heat insulation plate 12 abuts against the periphery of the first protrusion 14 from the combustion chamber 3 side by covering the inner surface side of the outer wall 6 of the first combustion section. Thus, a closed space 15 is formed in the recess on the inner surface side of the outer wall 6 of the first combustion section formed by the first protrusion 14. The closed space 15 is formed to close the outer periphery of the first protrusion 14 by the heat insulation plate 12 (see reference). Figure 4 ).

[0052] A second protrusion 16, bulging toward the interior of the enclosed space 15, is formed on the heat insulation plate 12 at a position corresponding to the enclosed space 15. The second protrusion 16 is formed as a roughly quadrilateral shape, slightly smaller than the first protrusion 14. Figure 2 and Figure 3 As shown, when viewed from the combustion chamber 3 side, the second protrusion 16 is formed as a concave portion.

[0053] like Figure 1 As shown, a plurality of air inlet holes 17 are formed on the outer wall 6 of the first combustion section where the first protrusion 14 is formed. The air inlet holes 17 are provided to allow external air to pass through the outer wall 6 of the first combustion section and be introduced into the enclosed space section 15.

[0054] like Figure 3 As shown, an outlet opening 18 is formed on the heat insulation plate 12 above the second protrusion 16, covering the enclosed space 15. The outlet opening 18 is an opening provided to allow air to pass through the heat insulation plate 12 and flow out from the enclosed space 15 into the combustion chamber 3. The outlet opening 18 is located above the air inlet hole 17 (downstream of the flow direction of the combustion exhaust).

[0055] Moreover, such as Figure 4 As shown, an inclined piece 19 is provided at the upper edge of the outlet opening 18. The inclined piece 19 is formed simultaneously with the outlet opening 18 when the outlet opening 18 is cut from the heat insulation plate 12 by bending the heat insulation plate 12 at the position corresponding to the outlet opening 18 toward the inside of the closed space 15. If the outlet opening 18 is horizontally elongated, the inclined piece 19 can also be formed in a horizontally elongated shape. Therefore, the inclined piece 19 acts like a reinforcing rib, increasing the strength of the heat insulation plate 12.

[0056] The outer wall 6 of the first combustion section and the heat insulation plate 12 form a closed space section 15. External air passes through the air inlet hole 17 and the outlet opening 18 and flows through the interior of the closed space section 15 to cool the outer wall 6 of the first combustion section and the heat insulation plate 12 that form the closed space section 15. That is, the part in which the closed space section 15 is provided can be cooled in a focused manner.

[0057] As described above, the combustion device in this embodiment is a suction combustion type. When this combustion device is a suction combustion type hot water supply device, the combustion chamber 3 becomes negative pressure during combustion operation (when the combustion fan is running). Therefore, in the enclosed space 15, since a flow occurs from the air inlet 17 to the outlet opening 18, the combustion exhaust gas in the combustion chamber 3 will not leak from the air inlet 17.

[0058] Furthermore, the enclosed space 15 can be formed to an appropriate size by the first protrusion 14 and the heat insulation plate 12, and the amount of air introduced into the enclosed space 15 can be easily set according to the size and number of air inlet holes 17. Moreover, as long as the enclosed space 15 is provided at a desired position on the outer wall 6 of the first combustion section, that position can be cooled in a focused manner.

[0059] Therefore, a closed space 15 is provided in the part of the outer wall 6 of the first combustion chamber that will have the highest temperature, and the amount of air introduced from the air inlet 17 is set to the minimum amount required for cooling. By setting it in this way, the amount of air from the outside flowing into the combustion chamber 3 can be reduced, and the outer wall 6 of the first combustion chamber and the heat insulation plate 12 can be cooled efficiently.

[0060] Furthermore, when the air introduced into the enclosed space 15 flows from the outlet opening 18 toward the combustion chamber 3, it comes into contact with the inclined plate 19 provided along the upper edge of the outlet opening 18 and is guided obliquely upward. As a result, the air entering the combustion chamber 3 from the enclosed space 15 can flow in parallel with the flow of combustion exhaust gas flowing in the combustion chamber 3 between the combustion exhaust gas and the heat insulation plate 12, thereby suppressing the temperature rise of the heat insulation plate 12.

[0061] The cover plate 13 is positioned below the first protrusion 14 and above the burner 4 (upstream of the first protrusion 14 in the direction of combustion exhaust flow and downstream of the burner 4 in the direction of combustion exhaust flow).

[0062] like Figure 3 As shown, the cover plate 13 has a blocking portion 20 at its lower end that blocks the space between the cover plate 13 and the outer wall 6 of the first combustion section. The blocking portion 20 prevents air from entering between the cover plate 13 and the outer wall 6 of the first combustion section. On the other hand, the blocking portion 20 provided at the lower end of the cover plate 13 guides air between the cover plate 13 and the burner 4.

[0063] Therefore, by utilizing the air curtain effect of the air passing between the cover plate 13 and the burner 4, it is possible to prevent the flame of the burner 4 from tilting towards the cover plate 13 and the heat insulation plate 12, thereby suppressing the overheating of the cover plate 13 and the heat insulation plate 12.

[0064] It should be noted that, in this embodiment, an example is shown in which a second protrusion 16 having a generally quadrilateral flat surface opposite to the first protrusion 14 is provided on the heat insulation plate 12. However, the second protrusion of the present invention is not limited to the shape shown in this embodiment.

[0065] For example, such as Figure 5 As shown, multiple elongated grooves 21 (non-through) extending longitudinally can also be formed laterally on the generally quadrilateral surface of the second protrusion 16 of the heat insulation plate 12, wherein the multiple grooves 21 are arranged at predetermined intervals. This increases the substantial surface area of ​​the second protrusion 16 within a relatively narrow area, thereby improving the cooling effect of the heat insulation plate 12.

[0066] Furthermore, in this embodiment, a combustion device in which the combustion fan is positioned at the top so that the combustion exhaust flows from bottom to top inside the combustion chamber 3 (with a heat exchange box 2 provided at the top of the combustion box 1) is described as an example. However, the present invention can also appropriately employ a combustion device in which the combustion fan is positioned at the bottom so that the combustion exhaust flows from top to bottom inside the combustion chamber 3 (having a structure formed by inverting the structure of this embodiment vertically), and the same effect can be obtained.

Claims

1. A combustion device, which is a suction combustion type combustion device, wherein a heat insulation plate is provided on the inner surface of a combustion chamber having a combustion chamber, a burner is housed inside the combustion chamber, and a combustion fan for supplying combustion air to the burner is positioned downstream of the flow direction of the combustion exhaust generated by the burner, the combustion device being characterized in that it comprises: An enclosed space is formed around a portion of the outer wall of the combustion chamber by means of the heat insulation plate; the enclosed space is formed in the portion of the outer wall of the combustion chamber between the heat insulation plate and the outer wall of the combustion chamber. An air inlet is formed on the outer wall of the combustion chamber at the location where the enclosed space is formed, and allows air to be introduced into the enclosed space; and, An outlet opening is formed on the heat insulation plate at the location where the enclosed space is formed, allowing air from the enclosed space to flow out into the combustion chamber. The enclosed space is formed inside the first protrusion by a first protrusion bulging outward from a portion of the outer wall of the combustion chamber and a heat insulation plate abutting against the periphery of the first protrusion on the outer wall of the combustion chamber.

2. The combustion device according to claim 1, characterized in that, The heat insulation plate has a second protrusion at a position corresponding to the first protrusion, which bulges into the interior of the enclosed space.

3. The combustion device according to claim 1 or 2, characterized in that, The outflow opening is formed on a downstream side that is further downstream of the burner and further downstream of the air inlet.

4. The combustion device according to claim 1 or 2, characterized in that, The heat insulation plate has an inclined plate that is inclined from the downstream end of the outflow opening toward the upstream side of the enclosed space and toward the outer wall of the combustion chamber.

5. The combustion device according to claim 1 or 2, characterized in that, It also includes a cover panel that is continuously disposed with the heat insulation plate and covers the inner surface of the combustion chamber at a position upstream of the enclosed space and downstream of the burner.

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