Premixing device and combustion apparatus including the same

Abstract

To provide a premixing device capable of increasing a turndown ratio by means with a simple configuration and preventing adverse effects of foreign matters in the air.SOLUTION: A premixing device A includes: a premixing flow passage 3 having first and second flow passages 3a, 3b extending in the vertical height direction and disposed in parallel in the horizontal direction; first and second fuel gas outflow ports 80a, 80b; and a flapper 5. The flapper 5 is provided on the upper side of a predetermined blade part 41a and a specific flow passage region 3a' to be swingable in the vertical height direction, swings in the vertical height direction by using its own weight as lowering force and an air flow advancing in the specific flow passage region 3a' upwardly from the lower side as lifting force, and can simultaneously open / close the first fuel gas outflow port 80a and the specific flow passage region 3a' in accordance with an air flow rate of the premixing flow passage 3.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a premixing device and a combustion device provided with the same. Here, "premixing" is a process of premixing air and fuel gas in advance to generate a combustible mixture for the purpose of performing premixing combustion.

Background Art

[0002] As a specific example of a premixing device, there is one described in Patent Document 1. The premixing device described in the same document has a venturi-shaped premixing flow path with one end open to the outside and the other end connected to the intake side of a fan. When the fan is driven, outside air flows in from the opening at the one end and flows in a predetermined direction. This premixing flow path is partitioned into first and second flow paths by a partition wall portion, and first and second fuel gas outlets are provided on the inner peripheral wall surfaces of these first and second flow paths, respectively. Further, a flapper that can swing to open and close the first flow path is provided in the first flow path. The opening degree of this flapper changes in response to the air flow rate such that the opening degree is smaller when the air flow rate in the first flow path is low than when it is high.

[0003] In such a premixing device, air flows through the premixing flow path, and a negative pressure acts on the first and second fuel gas outlets. As a result, fuel gas flows out from these first and second fuel gas outlets into the premixing flow path. This fuel gas is mixed with the air to generate a mixture. On the other hand, when the air flow rate is low, the flapper closes the first flow path of the premixing flow path. Therefore, the flow velocity of air in the second flow path increases, and the negative pressure acting on the second fuel gas outlet is strengthened. As a result, even when the air flow rate is low, an appropriate amount of fuel gas can flow out from the second fuel gas outlet due to the negative pressure. Such an action is effective in increasing the turndown ratio.

[0004] However, in the prior art described above, as will be described below, there was still room for improvement.

[0005] That is, the flapper only opens and closes the first flow path, and the first fuel gas outlet remains open. For this reason, for example, even if the first flow path is switched from the open state to the closed state by the flapper, there is a possibility that fuel gas may flow out from the first fuel gas outlet for a while thereafter. Furthermore, due to the pressure fluctuation of the first flow path affected by the air flow of the second flow path, there is also a possibility that air in the first flow path may flow into (backflow) the first fuel gas outlet, or fuel gas may flow out unnecessarily from the first fuel gas outlet. In this case, it is difficult to maintain the air-fuel mixture at a desired appropriate mixing ratio.

[0006] As a means for solving this problem, there is a means of further providing an additional flapper for opening and closing the first fuel gas outlet (see Patent Document 2). However, according to such a means, since two flappers for the first flow path and the first fuel gas outlet are used, the total number of parts increases, and the manufacturing cost becomes high. On the other hand, minute foreign matters may be mixed in the air supplied to the premixing flow path. Therefore, when providing an additional flap for opening and closing the first fuel gas outlet, it is desirable to appropriately avoid malfunction or jamming of the flap caused by foreign matters in the air.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present invention has been conceived under the circumstances as described above, and an object thereof is to provide a premixing device that can increase the turndown ratio by a simple means and is less susceptible to the adverse effects of foreign substances in the air, and a combustion device equipped with the same.

MEANS FOR SOLVING THE PROBLEMS

[0009] To solve the above problems, the present invention takes the following technical means.

[0010] The premixing device provided by the first aspect of the present invention extends in the vertical height direction such that air supplied from the outside can flow from the lower side to the upper side, and a premixing flow path for mixing fuel gas with the air to generate a mixture, a partition wall portion that partitions the premixing flow path into first and second flow paths arranged in parallel in the horizontal direction, first and second fuel gas outlets that can discharge fuel gas into the first and second flow paths by utilizing the negative pressure generated by the air flow in the first and second flow paths, and a flapper provided in the first flow path. The premixing device is characterized in that it includes a blade portion located at an intermediate position in the vertical height direction of the first flow path and having the first fuel gas outlet opening upward facing the downstream side in the air flow direction, and a specific flow path region that is a part of the first flow path adjacent to both or one side in the horizontal direction of the blade portion and having openings at the upper and lower portions. The flapper is provided so as to be swingable in the vertical height direction above the blade portion and the specific flow path region, and is configured to be able to simultaneously open and close both the first fuel gas outlet and the specific flow path region according to the air flow rate of the premixing flow path.

[0011] According to such a configuration, the following effects can be obtained. That is, when the air flow rate supplied to the premixing flow path is low, the first flow path (specific flow path region) is closed by the flapper, and the fuel gas flowing out from the second fuel gas outlet is mixed with the air flowing through the second flow path. On the other hand, when the air flow rate is high, air also flows in the first flow path, and the fuel gas flowing out from the first fuel gas outlet is mixed with this air. Therefore, similar to Patent Document 1, it is possible to increase the turndown ratio. Further, the flapper can not only open and close the first flow path (specific flow path region), but also open and close the first fuel gas outlet. Therefore, when the first flow path is in the closed state, the first fuel gas outlet is also simultaneously in the closed state, and it is possible to appropriately prevent a situation where fuel gas unnecessarily flows out from the first fuel gas outlet thereafter. As a means for achieving such a thing, it is not necessary to use a total of two flappers for the first flow path and the first fuel gas outlet. Therefore, the overall configuration can be simplified and the manufacturing cost can be reduced. Furthermore, the first fuel gas outlet opened and closed by the flapper faces the downstream side in the air flow direction. For this reason, it is possible to eliminate or reduce the risk that foreign matter in the air enters the first fuel gas outlet and causes jamming with the flapper. Also, since the flapper is provided above the blade portion and the specific flow path region, for example, compared with the case where the flapper is arranged upstream of them in the air flow direction, the degree to which the whole flapper is directly exposed to the air flow can be reduced. This is preferable for suppressing problems such as a decrease in the smoothness of the swinging operation due to foreign matter adhering to the flapper.

[0012] In the present invention, preferably, the flapper is swingable in the vertical height direction with a support portion that supports the base end portion of the flapper as a fulcrum, and the support portion is located above the first fuel gas outlet and the specific flow path region, and is provided at a position avoiding the directly above regions of these first fuel gas outlet and specific flow path region.

[0013] According to such a configuration, it is further preferable in suppressing that much of the air passing through the specific flow path region directly proceeds to the support portion of the flapper, and foreign matter in the air adheres to the support portion to hinder the swinging operation of the flapper. Further, since the support portion also avoids the position directly above the first fuel gas outlet, it is possible to appropriately avoid the situation where the air flow applying a negative pressure to the first fuel gas outlet is obstructed by the support portion.

[0014] In the present invention, preferably, an upward planar seating portion including an opening peripheral edge of the first fuel gas outlet and an opening peripheral edge on the downstream side in the air flow direction of the specific flow path region is provided, and the flapper includes a plate-shaped flapper main body portion that faces and contacts the seating portion when the flapper is in the closed state, and a connecting portion continuously provided to the flapper main body portion, and is swingable about a support portion that supports the connecting portion as a fulcrum. When the flapper is in the fully open state, the flapper main body portion is configured to be positioned closer to one side portion of the first flow path and stand upright in the vertical height direction.

[0015] According to such a configuration, when the flapper is in the fully open state, the flapper main body portion does not obstruct the air flow in the first flow path, and it is possible to reduce variations in negative pressure due to the air flow. As a result, it is possible to effectively cause the negative pressure due to the air flow to act stably on the first fuel gas outlet and promote the outflow of the fuel gas.

[0016] In the present invention, preferably, when the flapper is in the fully open state, the center of gravity of the flapper is positioned closer to the center of the first flow path than directly above the swing center of the flapper, and is configured to generate a rotational force for lowering the flapper in the closing direction.

[0017] According to such a configuration, when the air flow rate flowing through the first flow path decreases when the flapper is in the fully open state, the self-weight of the flapper can be utilized to accurately operate in the closing direction.

[0018] In the present invention, preferably, the blade portion is provided in a manner bridging two opposing locations on the inner peripheral wall portion of the first flow path, and as the specific flow path region, a pair of specific flow path regions are provided on both sides thereof so as to sandwich the blade portion in the horizontal direction.

[0019] According to such a configuration, when air flows through each of the pair of specific flow path regions, this air will pass on both sides of the first fuel gas outlet. Therefore, the negative pressure action due to the air flow can be efficiently applied to the first fuel gas outlet, which is preferable for allowing the fuel gas to flow out from the first fuel gas outlet with a sufficient flow rate.

[0020] The combustion device provided by the second aspect of the present invention is a combustion device including a premixing device that generates a mixture of air and fuel gas, and a burner portion that receives the supply of the mixture from the premixing device and burns the fuel gas, characterized in that as the premixing device, the premixing device provided by the first aspect of the present invention is used.

[0021] According to such a configuration, the same effects as those described for the premixing device provided by the first aspect of the present invention can be obtained.

[0022] Other features and advantages of the present invention will become more apparent from the following description of the embodiments of the invention with reference to the accompanying drawings.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0024] Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

[0025] FIG. 1 shows a hot water device WH. This hot water device WH is a water supply device and includes a premixing device A, a combustion device B (premixed combustion device), and a heat exchanger 11. The combustion device B is configured by combining a fan 1 and a burner section 2 with the premixing device A. The fan 1 is variable in speed (variable in air volume).

[0026] Details of the premixing device A will be described later. Using this premixing device A, an air-fuel gas mixture (flammable mixture) is generated, and this mixture is supplied to the burner section 2 via the fan 1. The burner section 2 includes a porous plate 21 having a plurality of vent holes 20 (flame holes) and is housed in a case 10. The burner section 2 is provided with an ignition plug (not shown), a flame detection sensor, and the like. The above mixture passes through the plurality of vent holes 20 and burns below the porous plate 21. The combustion gas generated by the burner section 2 acts on the heat exchanger 11, and the hot and cold water passing through the heat exchanger 11 is heated. Thereby, hot water is generated, and this hot water is supplied to a desired hot water supply destination.

[0027] As clearly shown in FIGS. 2 to 6, the premixing device A includes a device main body section A0 and a flapper 5 assembled to the device main body section A0. In the figure, both the x and y directions are horizontal directions and intersect each other.

[0028] The device main body section A0 includes a premixing flow path forming member 4 and a pipe joint section 70. The premixing flow path forming member 4 includes a cylindrical section 49 that forms a venturi-shaped premixing flow path 3 inside, a flange section 48 continuously provided at the upper end of the cylindrical section 49, and a stepped pedestal section 44 protruding from the outer surface section of the cylindrical section 49. The pipe joint section 70 is attached to the pedestal section 44 using a screw member 90 such as a screw so as to sandwich a fuel gas control plate 71 described later.

[0029] As shown in Fig. 1, the premixing device A has a pipe joint part 70 connected to a gas pipe 99 and receives the supply of fuel gas from a fuel gas supply source (not shown) via a pressure equalizing valve (zero governor) V1. On the other hand, the premixing device A is directly or indirectly connected to the intake side of the fan 1 using a flange part 48. When the fan 1 is driven, external air flows into the premixing flow path forming member 4 (the premixing flow path 3 in the cylindrical part 49). Due to the negative pressure action generated by this air flow, fuel gas flows out from the first and second fuel gas outlets 80a and 80b described later, and a mixture of this fuel gas and the air is generated. This mixture is supplied to the burner part 2 via the fan 1.

[0030] As well represented in Figs. 4(b), 5(b), and 6(b), a partition wall part 40 extending in the vertical height direction, which is the air flow direction, is provided in the premixing flow path 3. As a result, a part of the premixing flow path 3 is partitioned into first and second flow paths 3a and 3b arranged in the y direction with the partition wall part 40 interposed therebetween. The partition wall part 40 is arranged offset in the y direction from the center of the cylindrical part 49, and the first flow path 3a has a larger flow cross-sectional area than the second flow path 3b. However, alternatively, the first and second flow paths 3a and 3b may have the same flow cross-sectional area.

[0031] As well represented in Figs. 4 to 7, first and second blade parts 41a and 41b (the part with a dot pattern in Figs. 7(a) and 7(c)) are provided in the first and second flow paths 3a and 3b. Among these first and second blade parts 41a and 41b, first and second fuel gas outlets 80a and 80b are provided in an upward opening shape on the upper surface part as the main surface part facing the downstream side in the air flow direction. Note that the first blade part 41a corresponds to an example of the blade part of the present invention. The first and second blade parts 41a and 41b extend in the y direction so as to horizontally cross the first and second flow paths 3a and 3b respectively, and one ends thereof are connected to the inner surface of the peripheral wall of the premixing flow path 3 (the inner surface of the peripheral wall part of the cylindrical part 49), and the other ends thereof are connected to each other with the partition wall part 40 interposed therebetween.

[0032] As well represented by FIG. 7, the first blade portion 41a divides a part of the first flow path 3a into a pair of specific flow path regions (divided flow paths) 3a' through which air can flow. As a result, in the x direction, a pair of specific flow path regions 3a' are located on both sides of the first blade portion 41a. On the other hand, the second blade portion 41b divides a part of the second flow path 3b into a pair of divided flow paths 3b' through which air can flow. As a result, in the x direction, a pair of divided flow paths 3b' are located on both sides of the second blade portion 41b.

[0033] As shown in FIGS. 4(a), 5(a), and 6(a), the pipe joint portion 70 forms a fuel gas receiving portion 81 inside that receives the supply of fuel gas from the outside. The fuel gas supplied to this fuel gas receiving portion 81 is led to the first and second fuel gas outlets 80a, 80b through the openings 71a, 71b of the fuel gas control plate 71 and the first and second fuel gas flow paths 8a, 8b.

[0034] The second fuel gas flow path 8b is provided inside the second blade portion 41b and the pedestal portion 44, while the first fuel gas flow path 8a is provided inside the first and second blade portions 41a, 41b and the pedestal portion 44. The second blade portion 41b has a greater vertical thickness than the first blade portion 41a, and inside the second blade portion 41b, the first and second fuel gas flow paths 8a, 8b overlap in the vertical height direction. According to such a configuration, the fuel gas supply structure to the first and second fuel gas outlets 80a, 80b can be simplified. Further, by overlapping the first and second fuel gas flow paths 8a, 8b in the vertical height direction, the horizontal (x direction) width of the second blade portion 41b can be prevented from becoming too large, and it becomes possible to sufficiently secure the opening area of the pair of divided flow paths 3b'.

[0035] As described above, the fuel gas control plate 71 is attached to the pedestal portion 44 and has two openings 71a and 71b facing the tip openings of the first and second fuel gas flow paths 8a and 8b. The amount of fuel gas flowing into the first and second fuel gas flow paths 8a and 8b from the fuel gas receiving portion 81 can be controlled by the opening areas of these openings 71a and 71b.

[0036] An air inlet portion 3c and an air outlet portion 3d communicating with the first and second flow paths 3a and 3b are formed in the lower and upper portions inside the cylindrical portion 49. When the fan 1 is driven, external air can flow into the air inlet portion 3c and then branch into the first and second flow paths 3a and 3b. Due to the negative pressure action generated by the air flow in the first and second flow paths 3a and 3b, as described above, fuel gas flows out from the first and second fuel gas outlets 80a and 80b to generate an air-fuel gas mixture. This mixture flows out from the air outlet portion 3d to the outside of the cylindrical portion 49.

[0037] As shown in FIGS. 4 to 6, the flapper 5 can simultaneously open and close the first flow path 3a (a pair of specific flow path regions 3a') and the first fuel gas outlet 80a. More specifically, it has the following configuration.

[0038] That is, the flapper 5 is, for example, a resin molded product. As well represented in FIG. 8, it includes a plate-shaped flapper main body portion 50, a protruding step-shaped continuous portion 51 continuously provided on a part thereof, and a pair of fin portions 55 protruding downward from the flapper main body portion 50. The base end portion 5a of the flapper 5 is the portion including the continuous portion 51. A support portion 52 is provided at the continuous portion 51 of the flapper 5. This support portion 52 is a part that supports the continuous portion 51 so as to be swingable around the center line CL extending in the x direction, and a shaft body 61 serving as a swing fulcrum of the flapper 5 is provided through the continuous portion 51, and this shaft body 61 is a part supported by a pair of auxiliary members 60 having support holes 60a as well represented in Fig. 3. The pair of auxiliary members 60 are attached to a stepped portion 43 separately provided in the first flow path 3a using a screw member 92 or the like.

[0039] The flapper 5 is arranged above (downstream side in the air flow direction) the first blade portion 41a in the first flow path 3a, and is swingable in the vertical height direction around the support portion 52 (strictly, the center line CL). Thus, a pair of specific flow path regions 3a' of the first flow path 3a and the first fuel gas outlet 80a can be opened and closed simultaneously (see Figs. 4 to 6). The swing of the flapper 5 is performed using the self - weight of the flapper 5 as the downward force and the air flow traveling upward in each specific flow path region 3a’ as the upward force. When the air flow rate in the premixing flow path 3 is small, the opening degree of the flapper 5 becomes smaller than when it is large. When the air flow rate is small, the flapper 5 lies down due to its own weight and becomes the closed state (fully closed state) shown in Fig. 4. When the air flow rate increases, the flapper 5 is lifted by the upward air flow and changes to, for example, the open state (fully open state) shown in Fig. 5. Fig. 6 shows the state when the flapper 5 changes from the closed state to the open state (small opening state with the opening degree being less than or equal to a predetermined value).

[0040] When the flapper 5 is in the fully open state as shown in Fig. 5, it is located closer to one side of the first flow path 3a and is set to have a posture standing upright in the vertical height direction (including the state where the flapper main body portion 50 is vertical and the state inclined toward the partition wall portion 40). More preferably, the flapper main body portion 50 is arranged to avoid the position directly above the first fuel gas outlet 80a. Also, when the flapper 5 is fully open, the center of gravity of the flapper 5 is located closer to the center of the first flow path 3a than directly above the swing center (center line CL) of the flapper 5, and a rotational moment for lowering the flapper 5 is generated. Therefore, when the air flow rate in the first flow path 3a decreases, the flapper 5 correspondingly descends, and its opening degree becomes smaller.

[0041] As shown in FIG. 4, the closed state of the flapper 5 is a state in which the flapper main body portion 50 is in contact with the seat portion 47 in an opposing manner. Here, the seat portion 47 is an upward-facing surface portion of the first blade portion 41a that includes the peripheral edge of the first fuel gas outlet 80a and the upper opening peripheral edge of each specific flow path region 3a' (the opening peripheral edge on the downstream side in the air flow direction).

[0042] In the closed state of the flapper 5, as shown in FIG. 4(a), the first fuel gas outlet 80a is configured to be fully closed by the flapper 5. On the other hand, in the present embodiment, as shown in FIG. 4(b), each specific flow path region 3a' is not fully closed by the flapper 5, and a part 3a" located closer to the base end portion 5a of the flapper 5 in each specific flow path region 3a' is configured to be in an open state. In the closed state of the flapper 5, an air flow from each specific flow path region 3a' to the region downstream of the flapper 5 in the air flow direction can be generated via the part 3a". This helps to suppress a large change in the air-fuel ratio when the flapper 5 changes from the closed state to the open state, as will be described later.

[0043] The support portion 52 is provided in an offset arrangement on the downstream side in the air flow direction of the flapper main body portion 50 and the first fuel gas outlet 80a and on the side of the partition wall portion 40 when the flapper 5 is in the closed state. Preferably, the support portion 52 is arranged to avoid directly above each specific flow path region 3a' and the first fuel gas outlet 80a.

[0044] The continuous part 51 of the flap 5 is arranged to be spaced above the seat part 47 when the flap 5 is in the closed state, and a first gap C1 is formed between the continuous part 51 and the seat part 47. Further, in the downward region of the continuous part 51 facing the seat part 47, an inclined surface part 51a is formed which is inclined so that the separation distance La (see Fig. 8(b)) from the seat part 47 increases as it approaches the support part 52 side from the flap main body part 50 side. A second gap C2 communicating with the first gap C1 is formed between the continuous part 51 and the partition wall part 40.

[0045] When the flap 5 changes from the closed state shown in Fig. 4 to the open state (small opening state) shown in Fig. 6, auxiliary flow paths 38a and 38b on the base end side and the tip end side are formed between the respective regions on the base end part 5a side and the tip end part 5b side of the flap and the seat part 47. As a result, an air flow is generated from each specific flow path region 3a' via these auxiliary flow paths 38a and 38b on the base end side and the tip end side to the region downstream of the flap 5 in the air flow direction, and a fuel gas outflow from the first fuel gas outlet 80a is caused by the suction negative pressure action resulting from this air flow. More specifically, when the flap 5 is in the small opening state, the fuel gas and air (mixture) that have advanced through the auxiliary flow path 38b on the tip end side pass through the third gap C3 between the tip end part 5b of the flap 5 and the inner wall part of the first flow path 3a and flow into the region downstream of the flap 5 in the air flow direction. On the other hand, the fuel gas and air (mixture) that have advanced through the auxiliary flow path 38a on the base end side pass through the second gap C2 and flow into the region downstream of the flap 5 in the air flow direction. The auxiliary flow path 38a on the base end side is formed to include the above-mentioned first gap C1.

[0046] The pair of fin portions 55 of the flapper 5 project downward from the lower surface portion of the flapper 5 in a state of facing each other in parallel with a space therebetween (see also FIG. 8). As shown in FIGS. 4 and 6, when the flapper 5 is in the closed state and when it changes from the closed state to the open state, these pair of fin portions 55 are provided so as to sandwich the left and right sides of the first fuel gas outlet 80a and the first blade portion 41a. As will be described later, when the flapper 5 changes from the closed state to the open state, these pair of fins 55 help to suppress the phenomenon that the air in the first flow path 3a flows backward into the first and second fuel gas flow paths 8a and 8b due to the negative pressure generated in the second flow path 3b from the first fuel gas outlet 80a.

[0047] Next, the operation of the premixing device A described above and the combustion device B equipped with the same will be described.

[0048] During the driving combustion of the burner portion 2 of the combustion device B, the driving speed of the fan 1 is changed, and the flow rate of the air-fuel mixture supplied from the premixing device A to the burner portion 2 is changed, whereby the control of the driving combustion thermal power of the burner portion 2 is executed. Here, when the driving speed of the fan 1 is low and the air flow rate in the premixing flow path 3 is small, as shown in FIG. 4, the flapper 5 is in the closed state, and each specific flow path region 3a' of the first flow path 3a is blocked except for a part 3a" thereof, and air flows through the second flow path 3b. Therefore, the flow of air in this second flow path 3b can be accelerated, a strong negative pressure can be applied to the second fuel gas outlet 80b, and an appropriate amount of fuel gas corresponding to the air flow rate can be made to flow out into the second flow path 3b. On the other hand, when the driving speed of the fan 1 is high, for example, as shown in FIG. 5, the flapper 5 is in the open state, air flows sufficiently through both the first and second flow paths 3a and 3b, and an appropriate amount of fuel gas corresponding to the air flow rate can be made to flow out from both the first and second fuel gas outlets 80a and 80b. From such a situation, the turndown ratio can be increased.

[0049] The flapper 5 not only opens and closes the first flow path 3a, but also opens and closes the first fuel gas outlet 80a at the same time. Therefore, for example, when the first flow path 3a is in the closed state, the first fuel gas outlet 80a is also in the closed state at the same time, so that problems such as unnecessary outflow of fuel gas from the first fuel gas outlet 80a are appropriately prevented. As a means to achieve such a thing, since two flappers for the first flow path 3a and the first fuel gas outlet 80a are not used, the overall configuration of the premixing device A can be simplified and the manufacturing cost can be reduced.

[0050] In the present embodiment, the first fuel gas outlet 80a opened and closed by the flapper 5 faces the downstream side in the air flow direction. For this reason, it is possible to eliminate or reduce the risk that foreign matter mixed in the air enters the first fuel gas outlet 80a and causes jamming with the flapper 5. Further, since the flapper 5 is provided above the first blade portion 41a and each specific flow path region 3a', it is preferable in suppressing the degree of direct exposure to the air flow and suppressing the adhesion of foreign matter to the flapper 5. In particular, since the support portion 52 of the flapper 5 is arranged to retreat from directly above the first fuel gas outlet 80a and each specific flow path region 3a', it is possible to appropriately suppress the occurrence of obstacles to the swinging operation of the flapper 5 due to the adhesion of foreign matter to the support portion 52. Furthermore, since the support portion 52 also avoids the position directly above the first fuel gas outlet 80a, it is also appropriately avoided that the air flow applying negative pressure to the first fuel gas outlet 80a is obstructed by the support portion 52.

[0051] When the flapper 5 is fully opened, the flapper main body portion 50 is located closer to one side portion of the first flow path 3a in an upright posture in the vertical height direction. For this reason, when the flapper 5 is in the fully open state, it is possible to appropriately prevent the flapper main body portion 50 from obstructing the air flow in the first flow path 3a and reduce the occurrence of variations in negative pressure due to the air flow. As a result, it is possible to effectively cause the negative pressure due to the air flow to act stably on the first fuel gas outlet 80a and promote the outflow of fuel gas.

[0052] In this embodiment, a pair of specific flow path regions 3a' are provided on both sides of the first blade portion 41a and the first fuel gas outlet 80a so as to sandwich them. Therefore, when air flows through each of the pair of specific flow path regions 3a', the negative pressure action caused by these air flows acts on the first fuel gas outlet 80a from both sides thereof. Accordingly, the suction negative pressure can be made strong, and a corresponding amount of fuel gas can be accurately discharged from the first fuel gas outlet 80a. A pair of divided flow paths 3b' are located on both sides of the second fuel gas outlet 80b. Since air flows through these portions, when air flows through the pair of divided flow paths 3b' based on the same principle as described above, the negative pressure can be accurately applied to the second fuel gas outlet 80b.

[0053] When the air flow rate in the premixing flow path 3 increases from less than a predetermined value to a value equal to or greater than the predetermined value, as described above, the flapper 5 changes from the closed state shown in FIG. 4 to the open state (small opening state) shown in FIG. 6. At this time, in this embodiment, the following operations can be obtained.

[0054] That is, auxiliary flow paths 38a and 38b on the base end side and the tip end side communicate with the second gap C2 and the third gap C3 between the regions on the base end portion 5a side and the tip end portion 5b side of the flapper 5 and the seat portion 47, respectively, to be formed. Therefore, a smooth air flow is generated from each specific flow path region 3a' of the first flow path 3a toward the region downstream of the flapper 5 in the air flow direction through these portions. Along with this, the negative pressure caused by the air flow can be applied to the first fuel gas outlet 80a to cause fuel gas outflow. Therefore, immediately after the flapper 5 changes from the closed state to the open state, the outflow amount of fuel gas to the first flow path 3a can be sufficiently ensured, and it is possible to suppress the air-fuel mixture from having an inappropriate air-fuel ratio with a fuel lean state. As a result, it is possible to make the performance of maintaining a constant air-fuel ratio excellent.

[0055] In particular, in the present embodiment, even when the flapper 5 is in the closed state shown in FIG. 4, each specific flow path region 3a' is not in a fully closed state, and a part 3a" near the base end portion 5a of the flapper 5 is in an open state, and an air flow is generated in this part. Therefore, even immediately after the flapper 5 changes to the open state, it is preferable for sufficiently securing the air flow rate in the auxiliary flow path 38a on the base end side of the flapper 5 and promoting the outflow of the fuel gas from the first fuel gas outlet 80a. When the flapper 5 changes from the closed state to the open state, as shown in FIG. 6, the flapper 5 is inclined so that the tip portion 5b side is separated from the seat portion 47 more than the base end portion 5a side. For this reason, originally, the auxiliary flow path 38a on the base end side would be a narrower flow path than the auxiliary flow path 38b on the tip side, and the air flow rate in the auxiliary flow path 38a on the base end side would tend to decrease. On the other hand, according to the above configuration of the present embodiment, it helps to eliminate such a situation.

[0056] In the present embodiment, when the flapper 5 is in the closed state, a first gap C1 is formed between the continuous portion 51 of the flapper 5 and the seat portion 47, and as well represented in FIG. 9(a), when the flapper 5 changes to the open state, the first gap C1 is included in the auxiliary flow path 38a on the base end side and forms this auxiliary flow path 38a. Therefore, it can be easily achieved to increase the overall size of the auxiliary flow path 38a on the base end side and secure the air flow rate in this part. Also, in the present embodiment, the distance Lb from the swing center of the flapper 5 to the base end 50a of the flapper main body portion 50 is taken to be relatively large. For this reason, when the flapper 5 changes to the open state, it is also possible to increase the dimensional length Lc between the base end 50a of the flapper main body portion 50 and the seat portion 47 (see the right figure in FIG. 9(a)).

[0057] Fig. 9(b) shows Comparative Example 1 with respect to the present embodiment. In this Comparative Example 1, when the flapper 5E is in the closed state shown in the left figure of this figure, a portion corresponding to the first gap C1 of the present embodiment is not formed. Further, when the flapper 5E shown in the right figure of this figure changes to the open state, the lower surface of the base end portion of the flapper 5E abuts against the seat portion 47, and a portion corresponding to the auxiliary flow path 38a on the base end side of the present embodiment is not formed. According to such a configuration, it is difficult to appropriately discharge the fuel gas from the first fuel gas outlet 80a. On the other hand, according to the present embodiment, such a problem is appropriately solved.

[0058] In the present embodiment, as shown in the right figure of Fig. 10(a), when the flapper 5 has a slightly large opening degree, a part of the air traveling from below collides with the continuous portion 51. On the other hand, an inclined surface portion 51a is formed on the continuous portion 51, and the air that has collided with the inclined surface portion 51a can be smoothly advanced obliquely upward.

[0059] Fig. 10(b) shows Comparative Example 2 with respect to the present embodiment. In this Comparative Example 2, a portion corresponding to the inclined surface portion 51a of the present invention is not provided on the flapper 5F. In this Comparative Example 2, as shown in the right figure of this figure, when air collides with the base end portion of the flapper 5F, this air becomes a turbulent flow that reflects in various directions. This inhibits the smooth outflow of the fuel gas. On the other hand, according to the present embodiment, such a problem is appropriately solved.

[0060] The first and second fuel gas flow paths 8a and 8b communicate with each other via the fuel gas receiving portion 81. Therefore, originally, when the flapper 5 changes from the closed state to the open state, the air in each specific flow path region 3a' of the first flow path 3a may flow backward into the first and second fuel gas flow paths 8a and 8b due to the negative pressure generated in the second flow path 3b. On the other hand, according to the present embodiment, as described above, by forming the auxiliary flow paths 38a and 38b on the base end side and the tip end side, the air flow to the region downstream in the air flow direction from the flapper 5 is promoted, so that the above-described backflow of air is appropriately suppressed. Further, in the present embodiment, the pair of fin portions 55 serve as resistance against the backflow, and the backflow phenomenon is more surely suppressed.

[0061] The present invention is not limited to the contents of the above-described embodiments. The specific configurations of each part of the premixing device and the combustion device according to the present invention can be variously designed and changed within the scope intended by the present invention.

[0062] The premixing flow path is preferably in a venturi shape, but is not limited thereto. The specific shapes, sizes, materials, etc. of the first and second blade portions, the flapper, etc. are not limited to the above-described embodiments. The first and second fuel gas outlets may be provided not one by one, but for example, a plurality of them may be provided. The specific flow path region is not limited to the configuration provided in a pair on both sides of the first blade portion in the x direction, and may be configured to be provided only on one side of the first blade portion.

[0063] As means for making the flapper swingable, instead of means using a shaft body made of metal or the like separate from the flapper, for example, a convex portion serving as a swing center of the flapper is provided on one of the flapper or the support member of the flapper, and a concave portion into which the convex portion is fitted is provided on the other, and the like means can be used. In the above-described embodiment, when the flapper is in the closed state, a part of the specific flow path region is in an open state and is not in a fully closed state, but the present invention is not limited thereto. In the present invention, when the flapper is in the closed state, the specific flow path region can also be configured to be fully closed.

[0064] The fuel gas is, for example, natural gas or LP gas, but its specific type is not limited. The combustion device according to the present invention is not limited to being used for a hot water device, and can also be, for example, a combustion device for other uses such as heating or incineration. Further, it is not limited to the type in which the combustion gas travels downward, and can also be, for example, a type in which the combustion gas travels upward.

Explanation of Reference Numerals

[0065] A premixing device B combustion device C1, C2 First and second gaps 1 Fan 2 Burner 3 Premixing flow path 3a, 3b First and second flow paths 3a’ Specific flow path region 4 Premixing flow path forming member 40 Partition wall portion 41a First blade portion (blade portion) 41b Second blade portion 47 Seat portion 5 Flapper 5a Base end portion (of the flapper) 5b Tip end portion (of the flapper) 50 Flapper main body portion 51 Connecting portion 51a Inclined surface portion 52 Support portion 61 Shaft body 8a, 8b First and second fuel gas flow paths 80a, 80b First and second fuel gas outlets

Claims

1. It extends in the vertical height direction so that the air supplied from the outside can flow from the lower side to the upper side, and a premixing flow path for mixing fuel gas with the air to generate a mixture, A partition wall portion that partitions this premixing flow path into first and second flow paths arranged in parallel in the horizontal direction, First and second fuel gas outlets that can discharge fuel gas into the first and second flow paths by utilizing the negative pressure generated by the air flow in the first and second flow paths, A flapper provided in the first flow path, A premixing device comprising: A blade portion that is located at a middle position in the vertical height direction of the first flow path and is provided with an opening facing upward on the upper side where the first fuel gas outlet is downstream in the air flow direction, A specific flow path region as a part of the first flow path that is open at the upper and lower parts in an arrangement adjacent to both sides or one side in the horizontal direction of the blade portion, Comprising: The flapper is provided so as to be swingable in the vertical height direction above the blade portion and the specific flow path region, and is configured to be able to simultaneously open and close both the first fuel gas outlet and the specific flow path region according to the air flow rate of the premixing flow path. A premixing device characterized by this.

2. The premixing device according to Claim 1, The flapper is swingable in the vertical height direction with a support portion that supports the base end portion of the flapper as a fulcrum, The support portion is located above the first fuel gas outlet and the specific flow path region, and is provided at a position avoiding the directly above region of these first fuel gas outlet and specific flow path region. A premixing device.

3. The premixing device according to Claim 1, It comprises an upward-facing planar seating portion including the opening peripheral edge portion of the first fuel gas outlet and the opening peripheral edge portion on the downstream side in the air flow direction of the specific flow path region, The flapper comprises a plate-shaped flapper main body portion that faces and contacts the seating portion when the flapper is in the closed state, and a connecting portion continuously provided to the flapper main body portion, and is swingable with a support portion that supports this connecting portion as a fulcrum, When the flapper is in the fully open state, the flapper main body portion is configured to be located closer to one side portion of the first flow path and stand upright in the vertical height direction. A premixing device.

4. The premixing device according to Claim 3, The pre - mixer is configured such that when in the fully - open state, the center of gravity of the flapper is located closer to the center of the first flow path than directly above the swing center of the flapper, and a rotational force is generated to lower the flapper in the closing direction.

5. The pre - mixer according to claim 1, wherein the blade portion is provided in a manner bridging two opposing locations on the inner peripheral wall portion of the first flow path, and as the specific flow path region, a pair of specific flow path regions are provided on both sides thereof so as to sandwich the blade portion in the horizontal direction.

6. A pre - mixer for generating a mixture of air and fuel gas, a burner unit that receives the supply of the mixture from the pre - mixer and burns the fuel gas, and a combustion device comprising: The combustion device is characterized in that, as the pre - mixer, the pre - mixer according to any one of claims 1 to 5 is used.

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