Premixing device and combustion device equipped with premixing device

Abstract

The present invention addresses the problem of providing a premixing device and a combustion device equipped with the premixing device, the premixing device having excellent performance for maintaining a gas mixture at an appropriate mixing ratio while improving the adjustment ratio. A premixing device includes a premixing flow path including a first flow path and a second flow path, and a first fuel gas outlet and a second fuel gas outlet, the premixing device including: a first blade portion provided in the first flow path and provided with the first fuel gas outlet; a protruding wall portion provided on the first blade portion; and a baffle plate which swings at a position closer to the downstream side of the first flow path than the first blade part in the air flow direction, and when the baffle plate is in an open state with a predetermined opening degree or less, the protruding wall part can prevent air in the first flow path from flowing to the first fuel gas outlet.

Description

Technical Field

[0001] The present invention relates to a premixing device and a combustion device equipped with the premixing device.

[0002] Here, "premixing" is a process of pre-mixing air and fuel gas to generate a combustible mixture for the purpose of premixing combustion. Background Art

[0003] As a specific example of the premixing device, there is the premixing device described in Patent Document 1.

[0004] The premixing device described in this document includes a Venturi-shaped premixing flow path. One end side of the premixing flow path opens to the outside, and the other end side is connected to the intake side of a blower. When the blower is driven, outside air flows in from the opening portion on the one end side and flows in a specified direction. The premixing flow path is partitioned into a first flow path and a second flow path by a partition wall, and a first fuel gas outlet and a second fuel gas outlet are respectively provided on the inner peripheral wall surfaces of these first and second flow paths. In addition, a baffle that can swing in a manner of opening and closing the first flow path is provided in the first flow path. The baffle changes its opening degree corresponding to the air flow rate such that the opening degree becomes smaller when the air flow rate in the first flow path is small than when the air flow rate is large.

[0005] In such a premixing device, since air flows in the premixing flow path, a negative pressure acts on the first fuel gas outlet and the second fuel gas outlet, and the fuel gas flows out from these first and second fuel gas outlets into the premixing flow path. The fuel gas is mixed with the air to generate a mixture gas. On the other hand, the baffle closes the first flow path of the premixing flow path when the air flow rate is small. Therefore, the flow velocity of the air in the second flow path is increased, and the negative pressure acting on the second fuel gas outlet is enhanced. As a result, even when the air flow rate is small, an appropriate amount of fuel gas can flow out from the second fuel gas outlet by the negative pressure. Such an action is effective in improving the turndown ratio.

[0006] However, the prior art still has room for improvement as described below.

[0007] That is, the baffle in the prior art only opens and closes the first flow path, and the first fuel gas outlet remains open. Therefore, for example, even if the first flow path is switched from the open state to the closed state by the baffle, there is a risk that fuel gas will flow out of the first fuel gas outlet for a short period thereafter. In addition, the pressure in the first flow path changes due to the air flow in the second flow path. As a result, there is also a risk that air will flow into (backflow to) the first fuel gas outlet in the first flow path or fuel gas will unnecessarily flow out of the first fuel gas outlet. In this way, it is difficult to maintain the mixture gas at a desired and appropriate mixing ratio.

[0008] As a method of eliminating these problems, there is a method of further providing an additional baffle for opening and closing the first fuel gas outlet (see Patent Document 2). However, according to such a method, a total of two baffles for the first flow path and the first fuel gas outlet are used, so the overall number of parts increases and the manufacturing cost becomes high.

[0009] Furthermore, when the baffle changes from the closed state to the open state, the effective flow path area of the pre-mixing flow path changes sharply. Therefore, affected by this, in the second flow path, there is a risk that the flow velocity of the air flow that has been generated previously will decrease sharply. In this way, the mixing ratio of the mixture gas will also change sharply, and there is a risk that the mixture gas will become an inappropriate mixing ratio with lean fuel.

[0010] [Prior Art Documents]

[0011] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Laid-Open No. 2021-99204

[0013] [Patent Document 2] U.S. Patent No. 9,677,759

[0014] [Patent Document 3] Japanese Patent No. 6,738,493 Summary of the Invention

[0015] [Problems to be Solved by the Invention]

[0016] The present invention is conceived on the basis of the above reasons, and its object is to provide a pre-mixing device capable of improving the adjustment ratio by a simple structure and having excellent performance in maintaining the mixture gas at an appropriate mixing ratio, and a combustion device equipped with the pre-mixing device.

[0017] [Technical Means for Solving the Problems]

[0018] To solve the above problems, the following technical means are adopted in the present invention.

[0019] The premixing device provided by the first aspect of the present invention includes: a premixing flow path that is supplied with air from the outside and is configured to mix fuel gas into the air to generate a mixed gas; a partition wall portion that divides the premixing flow path into a first flow path and a second flow path arranged in parallel; and a first fuel gas outlet and a second fuel gas outlet that are configured to allow fuel gas to flow out into the first flow path and the second flow path by means of the negative pressure generated by the air flow in the first flow path and the second flow path. The premixing device is characterized in that it includes: a first vane portion provided in the first flow path and having the first fuel gas outlet provided in a manner facing the downstream side in the air flow direction; a protruding wall portion provided on the first vane portion so as to protrude from the edge portion of the first fuel gas outlet toward the downstream side in the air flow direction; and a baffle that swings in a direction facing the first vane portion at a position downstream of the first vane portion in the air flow direction in the first flow path and is configured to open and close the first flow path and the first fuel gas outlet together while avoiding interference with the protruding wall portion according to the air flow rate in the premixing flow path, and is configured to suppress the air flow in the first flow path from flowing into the first fuel gas outlet through the protruding wall portion when the baffle is in an open state with a specified opening degree or less.

[0020] According to such a configuration, when the air flow rate supplied to the premixing flow path is small, the first flow path is set to a closed state by the baffle, and the fuel gas flowing out from the second fuel gas outlet is mixed into the air flowing in the second flow path. On the other hand, when the air flow rate is large, air also flows in the first flow path, and the fuel gas flowing out from the first fuel gas outlet is mixed into the air. Therefore, like in Patent Document 1, the regulation ratio can be improved. Furthermore, according to the present invention, the following effects are obtained.

[0021] First, the baffle can not only open and close the first flow path but also open and close the first fuel gas outlet. Therefore, when the first flow path is set to a closed state, the first fuel gas outlet is also simultaneously set to a closed state, thereby appropriately preventing the unnecessary outflow of fuel gas from the first fuel gas outlet thereafter. As a mechanism for achieving such a situation, it is not necessary to use a total of two baffles for the first flow path and the first fuel gas outlet, so the overall structure can be simplified and the manufacturing cost can be reduced.

[0022] Second, in the prior art, when the baffle changes from the closed state to an open state (small open state) below a specified opening degree, there is a risk that the air in the first flow path may flow backward from the first fuel gas outlet to the first fuel gas flow path and the second fuel gas flow path due to the negative pressure generated in the second flow path. In contrast, in the present invention, when the baffle changes from the closed state to the open state, the protruding wall portion suppresses the inflow of the air in the first flow path into the first fuel gas outlet, so that the backward flow of the air can be appropriately prevented or suppressed. Therefore, when the baffle changes from the closed state to the open state, the inappropriate air-fuel ratio in which the air-fuel mixture becomes fuel-lean can be appropriately suppressed.

[0023] Third, when the baffle changes from the closed state to the open state, the protruding wall portion generates air resistance in the first flow path. Therefore, when the baffle changes from the closed state to the open state, a sharp decrease in the flow velocity of the air flow previously generated in the second flow path can be avoided. As a result, the inappropriate air-fuel ratio in which the air-fuel mixture becomes fuel-lean can be appropriately suppressed.

[0024] In the present invention, preferably, as a mechanism for avoiding interference between the baffle and the protruding wall portion, a hole portion is provided in the baffle, and the protruding wall portion enters the hole portion when the baffle is in an open state below the specified opening degree.

[0025] According to such a structure, interference between the baffle and the protruding wall portion can be surely avoided by a simple structure in which only a hole portion is provided in the baffle. This is preferable in terms of suppressing an increase in manufacturing cost or weight.

[0026] In the present invention, preferably, the protruding wall portion has a height such that it comes out of the hole portion of the baffle when the baffle is in an open state greater than the specified opening degree.

[0027] According to such a structure, when the air flow rate supplied to the premixed flow path is large and the opening degree of the baffle becomes large, the air resistance of the protruding wall portion can be prevented from becoming too large.

[0028] In the present invention, preferably, the hole portion of the baffle is in the shape of a long hole extending in a specific direction from the base end portion side close to the swing center of the baffle to the front end portion, the protruding wall portion is in the shape of a rib extending in a direction corresponding to the specific direction, and a planar or curved chamfered portion is provided at a corner portion on the side of the front end portion of the protruding wall portion away from the swing center of the baffle.

[0029] According to such a structure, when the baffle swings, interference between the baffle and the corner portion of the front end portion of the protruding wall portion can be appropriately avoided by the presence of the chamfered portion. This is preferable in terms of reducing the size of the hole portion provided in the baffle.

[0030] In the present invention, preferably, the protruding wall portion extends in series along the first fuel gas outlet, and its length is substantially the same as the length of the first fuel gas outlet.

[0031] According to such a structure, the length of the protruding wall portion is not excessively short or less than the length of the first fuel gas outlet. As a result, while avoiding the adverse condition that the protruding wall portion becomes unnecessarily large and the air resistance increases, the desired effect of the present invention can be appropriately obtained, that is, the effect of suppressing the air flow in the first flow path from flowing toward the first fuel gas outlet when the baffle is in an open state below a specified opening degree (small opening state).

[0032] In the present invention, preferably, as the directions intersecting the air flow direction, there are an x direction and a y direction intersecting each other. The first vane portion divides a part of the first flow path into a pair of divided flow paths by extending along the y direction in a manner bridging between a part and another part of the inner wall of the first flow path. Moreover, in the x direction, the first vane portion and the first fuel gas outlet are located between the pair of divided flow paths. As the protruding wall portion, it includes a pair of protruding wall portions located at both edges in the x direction of the first fuel gas outlet.

[0033] According to such a structure, when the baffle is in an open state and air flows in the first flow path, the air flows in a pair of divided flow paths on both sides in the x direction of the first fuel gas outlet. Therefore, the negative pressure of the air flow can be utilized to appropriately discharge a fuel gas amount corresponding to the air flow rate from the first fuel gas outlet. On the other hand, in the case where the baffle is in an open state below a specified opening degree, the pair of protruding wall portions are provided to appropriately suppress the air from flowing separately from the pair of divided flow paths and flowing back to the first fuel gas outlet.

[0034] In the present invention, preferably, it is configured such that the protruding wall portion is not provided at both edges in the y direction of the first fuel gas outlet in the first vane portion, and when the baffle is in an open state below the specified opening degree, the air in the first flow path flows toward both edges in the y direction of the first fuel gas outlet.

[0035] According to such a structure, when the baffle is in an open state below a specified opening degree, the air in the first flow path flows near both edges in the y direction of the first fuel gas outlet, whereby the negative pressure generated by the air flow can be utilized to discharge the fuel gas from the first fuel gas outlet to the first flow path. It is possible to appropriately prevent the case where the pair of protruding wall portions provided at both edges in the x direction of the first fuel gas outlet hinder the outflow of the fuel gas from the first fuel gas outlet.

[0036] In the present invention, preferably, it further includes: a pre-mixing flow path forming member that forms the pre-mixing flow path; a second blade portion that is disposed in the second flow path such that one end portion is connected to the peripheral wall portion of the pre-mixing flow path forming member and the other end portion is connected to the first blade portion via the partition wall portion, and a second fuel gas outlet is disposed in a manner facing the downstream side of the air flow direction; a fuel gas receiving portion that is disposed on the peripheral wall portion of the pre-mixing flow path forming member and receives the supply of fuel gas from the outside; a second fuel gas flow path that is disposed in the second blade portion in a manner capable of guiding a part of the fuel gas supplied to the fuel gas receiving portion to the second fuel gas outlet; and a first fuel gas flow path that extends from inside the second blade portion to inside the first blade portion in a manner capable of guiding another part of the fuel gas supplied to the fuel gas receiving portion to the first fuel gas outlet.

[0037] According to such a structure, the fuel gas can be properly and reasonably guided from the fuel gas receiving portion provided on the outer surface portion of the pre-mixing flow path forming member to the first fuel gas outlet and the second fuel gas outlet by the first fuel gas flow path and the second fuel gas flow path provided in the first blade portion and the second blade portion. The fuel gas receiving portion may also be one part and there is no need to provide a plurality of them corresponding to each of the first fuel gas outlet and the second fuel gas outlet. Therefore, it is suitable for simplifying the overall structure and seeking to reduce the manufacturing cost, etc.

[0038] In addition, according to the structure of the second blade portion and the second fuel gas outlet provided in the second blade portion, when air flows near the second blade portion, a negative pressure can be effectively generated, and the negative pressure strongly acts on the second fuel gas outlet. Therefore, in the case where the baffle of the first flow path is in a closed state due to a small supply amount of air to the pre-mixing flow path and the fuel gas only flows out from the second fuel gas outlet, the outflow amount of the fuel gas can be sufficiently ensured and the adjustment ratio can be improved, which is more preferable in this regard.

[0039] The combustion device provided by the second aspect of the present invention includes: a blower; a pre-mixing device that is disposed on the intake side of the blower, generates a mixed gas formed by mixing air and fuel gas, and sends the mixed gas into the blower; and a burner portion that receives the supply of the mixed gas from the blower and burns the fuel gas. The combustion device is characterized in that the pre-mixing device provided by the first aspect of the present invention is used as the pre-mixing device.

[0040] According to such a structure, the same effects as those described for the pre-mixing device provided by the first aspect of the present invention can be obtained.

[0041] The description of the embodiments of the invention given below with reference to the accompanying drawings will further clarify other features and advantages of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 FIG. is a schematic explanatory view showing an example of a combustion apparatus equipped with the premixing device of the present invention.

[0043] Figure 2 is Figure 1 a perspective view of the appearance of the premixing device.

[0044] Figure 3 is Figure 2 an exploded perspective view.

[0045] Figure 4 (a) of FIG. is Figure 1 a front sectional view of the premixing device shown in FIG., Figure 4 (b) of FIG. is Figure 4 a sectional view of the premixing device at a position different from (a) of FIG., Figure 1 shown in FIG., Figure 4 (c) of FIG. is Figure 4 a sectional view taken along line IVc-IVc (main part sectional view of the right side) of (a) of FIG.

[0046] Figure 5 (a) of FIG. is a front sectional view showing a case where the baffle of the premixing device shown in (a) of FIG. is in a fully open state, Figure 4 shown in FIG., Figure 5 (b) of FIG. is Figure 5 a main part sectional view of the right side of (a) of FIG.

[0047] Figure 6 (a) of FIG. is a front sectional view showing a case where the baffle of the premixing device shown in (a) of FIG. is in an open state below a specified opening degree, Figure 4 shown in FIG., Figure 6 (b) of FIG. is Figure 6 a main part sectional view of the right side of (a) of FIG., Figure 6 (c) of FIG. is Figure 6 a partially enlarged sectional view of (b) of FIG.

[0048] Figure 7 (a) of FIG. is Figures 2 to 6 from (a) to Figure 6 a plan view of the premixing flow path forming member of the premixing device shown in (c) of FIG., Figure 7 (b) of FIG. is a partially enlarged view thereof, Figure 7 (c) of FIG. is a plan sectional view of the premixing flow path forming member.

[0049] Figure 8 is a view showing Figures 2 to 6of (a) to Figure 6 Main - part sectional view showing the relationship between the baffle plate and the protruding wall portion of the premixing device shown in (c).

[0050] [Explanation of symbols]

[0051] A: Premixing device

[0052] B: Combustion device

[0053] 1: Fan

[0054] 2: Burner section

[0055] 3: Premixing flow path

[0056] 3a, 3b: First flow path and second flow path

[0057] 4: Premixing - flow - path forming member

[0058] 40: Partition wall section

[0059] 41a, 41b: First blade section and second blade section

[0060] 45: Protruding wall portion

[0061] 45a: Corner portion

[0062] 45b: Chamfered portion

[0063] 5: Baffle plate

[0064] 55: Hole portion

[0065] 8a, 8b: First fuel - gas flow path and second fuel - gas flow path

[0066] 80a, 80b: First fuel - gas flow outlet and second fuel - gas flow outlet

[0067] 81: Fuel - gas receiving portion Detailed implementation mode

[0068] Hereinafter, with reference to the drawings, the preferred implementation modes of the present invention will be specifically described.

[0069] Figure 1 The hot - water device WH is shown. The hot - water device WH is a hot - water supply device, including a premixing device A, a combustion device B (premixed combustion device), and a heat exchanger 11. The combustion device B is composed of a fan 1 and a burner section 2 combined in the premixing device A. The fan 1 is variable - speed (the air - supply volume is variable).

[0070] Details of the premixing device A will be described later. A mixture of air and fuel gas (combustible mixture) is generated using the premixing device A, and the mixture is supplied to the burner section 2 via the blower 1. The burner section 2 includes a porous plate 21 having a plurality of ventilation holes 20 (flame holes) and is housed in the housing 10. An ignition spark plug or a flame detection sensor (not shown) is attached to the burner section 2. The mixture passes through the plurality of ventilation 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 water in the heat exchanger 11 is heated. Thereby, hot water is generated, and the hot water is supplied to a desired hot water supply destination.

[0071] As Figures 2 to 6 shown in (a) to Figure 6 shown in detail in (c) of FIG., the premixing device A includes a device main body section A0 and a baffle 5 assembled to the device main body section A0.

[0072] In addition, in the figure, the x-direction and the y-direction are mutually intersecting directions and are directions intersecting the air flow direction in the premixing flow path 3 described later. In the present embodiment, the air flow direction in the premixing flow path 3 is the vertical height direction of the premixing device A.

[0073] The device main body section A0 includes a premixing flow path forming member 4 and a pipe connection head 70.

[0074] The premixing flow path forming member 4 includes a cylindrical portion 49 forming a venturi-shaped premixing flow path 3 inside, a flange portion 48 connected to the upper end of the cylindrical portion 49, and a stepped base portion 44 protruding from the outer surface portion of the cylindrical portion 49. The pipe connection head 70 is attached to the base portion 44 using a threaded member 90 such as a screw so as to sandwich a fuel gas control plate 71 described later.

[0075] As Figure 1 shown in FIG., in the premixing device A, the pipe connection head 70 is connected to the gas pipe 99, and fuel gas is supplied from a fuel gas supply source (not shown) via a pressure equalizing valve (zero pressure valve) V1. On the other hand, the premixing device A is directly or indirectly connected to the intake side of the blower 1 using the flange portion 48. When the blower 1 is driven, external air flows into the premixing flow path forming member 4 (the premixing flow path 3 inside the cylindrical portion 49). Due to the negative pressure generated by the flow of the air, the fuel gas flows out from a first fuel gas outlet 80a and a second fuel gas outlet 80b described later, and a mixture of the fuel gas and the air is generated. The mixture is supplied to the burner section 2 via the blower 1.

[0076] As Figure 4As shown in detail in (b), a partition wall portion 40 extending in the air flow direction, i.e., the vertical height direction, is provided in the premixing flow path 3. As a result, a part of the premixing flow path 3 is partitioned by the partition wall portion 40 into a first flow path 3a and a second flow path 3b arranged in the y direction. The partition wall portion 40 is arranged to be offset from the center of the cylindrical portion 49 in the y direction, and the flow path area of the first flow path 3a is larger than that of the second flow path 3b. However, the first flow path 3a and the second flow path 3b may also be provided with the same flow path area.

[0077] As Figure 4 shown in (a) to Figure 4 shown in (c) to Figure 7 shown in (a) to Figure 7 shown in detail in (c) of (a) to (c), a first blade portion 41a and a second blade portion 41b are provided in the first flow path 3a and the second flow path 3b (in Figure 7 shown in (a) of Figure 7 shown in (c), they are dot pattern portions). The first fuel gas outlet 80a and the second fuel gas outlet 80b are provided in an upward-opening manner on the upper surface portion of the main surface portions of these first blade portion 41a and second blade portion 41b that face the downstream side in the air flow direction.

[0078] The first blade portion 41a and the second blade portion 41b extend in the y direction so as to cross the first flow path 3a and the second flow path 3b in the horizontal direction respectively, and one end portion of each of them is connected to the inner surface portion of the peripheral wall of the premixing flow path 3 (the inner surface portion of the peripheral wall portion of the cylindrical portion 49), and the other end portions of them are connected to each other via the partition wall portion 40.

[0079] As Figure 7 shown in (a) to Figure 7 shown in detail in (c) of (a) to (c), the first blade portion 41a divides a part of the first flow path 3a into a pair of divided flow paths 3a' through which air can flow. As a result, in the x direction, the first blade portion 41a and the first fuel gas outlet 80a are located between the pair of divided flow paths 3a'.

[0080] 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, and in the x direction, the second blade portion 41b and the second fuel gas outlet 80b are located between the pair of divided flow paths 3b'.

[0081] In Figure 4In (a) of [description], the tube body joint part 70 has a fuel gas receiving part 81 formed inside to receive the supply of fuel gas from the outside. The fuel gas supplied to the fuel gas receiving part 81 passes through the opening 71a, opening 71b of the fuel gas control plate 71, and the first fuel gas flow path 8a and the second fuel gas flow path 8b, and is guided to the first fuel gas outlet 80a and the second fuel gas outlet 80b.

[0082] Here, the second fuel gas flow path 8b is provided inside the second blade part 41b and the base part 44. In contrast, the first fuel gas flow path 8a is provided inside the first blade part 41a, the second blade part 41b, and the base part 44. The vertical thickness of the second blade part 41b is larger than the vertical thickness of the first blade part 41a. Inside the second blade part 41b, the first fuel gas flow path 8a and the second fuel gas flow path 8b overlap in the vertical height direction. According to such a structure, the simplification of the fuel gas supply structure to the first fuel gas outlet 80a and the second fuel gas outlet 80b can be achieved. In addition, as long as the first fuel gas flow path 8a and the second fuel gas flow path 8b overlap in the vertical height direction, it is possible to prevent the horizontal width (x-direction) of the second blade part 41b from being too large and to sufficiently ensure the opening area of the pair of divided flow paths 3b'.

[0083] As described above, the fuel gas control plate 71 is installed on the base part 44 and has two openings 71a, 71b facing the top openings of the first fuel gas flow path 8a and the second fuel gas flow path 8b. By setting the opening areas of these openings 71a, 71b to be of what kind, the inflow amount of fuel gas from the fuel gas receiving part 81 to the first fuel gas flow path 8a and the second fuel gas flow path 8b can be controlled.

[0084] An air flow inlet part 3c and an air flow outlet part 3d communicating with the first flow path 3a and the second flow path 3b are formed in the lower part and the upper part inside the cylindrical part 49. When the fan 1 is driven, the outside air can branch and flow into the first flow path 3a and the second flow path 3b after flowing into the air flow inlet part 3c. Due to the negative pressure effect generated by the air flow in the first flow path 3a and the second flow path 3b, as described above, the fuel gas flows out from the first fuel gas outlet 80a and the second fuel gas outlet 80b to generate a mixture of air and fuel gas. The mixture flows out from the air flow outlet part 3d to the outside of the cylindrical part 49.

[0085] The baffle 5 is, for example, a resin molded product, disposed on the upper side (downstream side in the air flow direction) of the first blade part 41a in the first flow path 3a, and can swing facing the upper surface part of the first blade part 41a in such a way as to simultaneously open and close the first flow path 3a (strictly speaking, a pair of divided flow paths 3a') and the first fuel gas outlet 80a (refer toFigure 4 of (a) to Figure 4 of (c) to Figure 6 of (a) to Figure 6 of (c)). More specifically, a shaft body 61 serving as a swing fulcrum (swing center) is inserted through the rear portion of the baffle 5, and the shaft body 61 is supported by a pair of left and right support members 60. In addition, the pair of support members 60 are mounted on a step portion 43 separately provided in the first flow path 3a using a screw member 92 or the like.

[0086] The baffle 5 changes its opening degree according to the air flow rate in such a manner that the opening degree is smaller when the air flow rate in the premixing flow path 3 is small than when the air flow rate is large. When the air flow rate is small, the baffle 5 topples due to its own weight and becomes Figure 4 of (a) to Figure 4 the closed state (fully closed state) shown in (c). When the air flow rate increases, the baffle 5 is lifted by the upward air flow and changes, for example, to Figure 5 the open state (fully open state) shown in (a) of Figure 5 and (b). Figure 6 of (a) to Figure 6 of (c) is a small open state where the opening degree of the baffle 5 is below a specified value.

[0087] As Figure 7 of (a) to Figure 7 shown in (c), a pair of protruding wall portions 45 are provided on the upper surface portion of the first blade portion 41a.

[0088] The pair of protruding wall portions 45 protrude upward from the upper surface portion of the first blade portion 41a and are located at the two edge portions in the x direction of the first fuel gas outlet 80a. Thus, in the x direction, the first blade portion 41a, the pair of protruding wall portions 45, and the first fuel gas outlet 80a are located between the pair of divided flow paths 3a'. Each protruding wall portion 45 is in the form of a rib extending in a string along the y direction in a manner following the first fuel gas outlet 80a, and preferably the length La of each protruding wall portion 45 in the y direction is substantially the same as the length Lb of the first fuel gas outlet 80a.

[0089] On the other hand, no protruding wall portions 45 or similar portions are provided at the two edge portions 46 in the y direction of the first fuel gas outlet 80a on the upper surface portion of the first blade portion 41a.

[0090] Regarding the baffle 5, a pair of hole portions 55 are provided as a mechanism for avoiding interference with the pair of protruding wall portions 45 during its swinging operation. The pair of hole portions 55 are provided when the baffle 5 is in Figure 4 of (a) to Figure 4 of (c) and Figure 6 of (a) toFigure 6 When in the closed state or small opening state shown in (c), a through hole into which each protruding wall portion 45 can enter. In addition, each hole portion 55 has a shape corresponding to each protruding wall portion 45 and is in the shape of a long hole extending in a specific direction from the base end portion side near the swing center of the baffle 5 to the front end portion.

[0091] The size of each protruding wall portion 45 is formed such that when the baffle 5 is in Figure 6 the specified small opening state shown in (a) to Figure 6 the (c) and there is a gap formed between the baffle 5 and the first blade portion 41a, each region between one of the pair of divided flow paths 3a' of the first flow path 3a and the first fuel gas outlet 80a can be blocked. Thus, each protruding wall portion 45 functions to suppress the air flow in the first flow path 3a from flowing toward the first fuel gas outlet 80a. In addition, the height of each protruding wall portion 45 is such a height that when the baffle 5 is in an opening state larger than the small opening state where the opening degree is not below the specified value, it can escape from the hole portion 55 of the baffle 5.

[0092] As Figure 8 shown, the side view shape of each protruding wall portion 45 is a substantially rectangular shape. Among them, a chamfered portion 45b having a curved surface shape with a radius of curvature Ra is provided at a corner portion 45a on the side of the front end portion of each protruding wall portion 45 that is far from the shaft body 61 which is the swing center of the baffle 5. This is preferable in terms of avoiding Figure 8 interference between the peripheral portion a1 on one end side of the hole portion 55 of the baffle 5 shown in moving along an arc trajectory with a radius Rb centered on the shaft body 61 and the corner portion 45a of the protruding wall portion 45. The chamfered portion 45b may also be a planar chamfered portion instead of a curved surface shape.

[0093] Next, the functions of the pre - mixing device A and the combustion device B equipped with the pre - mixing device A will be described.

[0094] At the start of the driving combustion of the burner portion 2 of the combustion device B or during the subsequent normal driving combustion, the driving speed of the blower 1 is changed. Thereby, the flow rate of the mixed gas supplied from the pre - mixing device A to the burner portion 2 is also changed, so that the driving combustion firepower of the burner portion 2 can be controlled.

[0095] Here, when the driving speed of the blower 1 is low and the air flow rate in the pre - mixing flow path 3 is small, as Figure 4 shown in (a) to Figure 4As shown in (c), the baffle 5 is in the closed state, and no air flows in the first flow path 3a. In this case, only air flows in the second flow path 3b. Therefore, by increasing the flow speed of the air in the second flow path 3b and applying a strong negative pressure to the second fuel gas outlet 80b, 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 blower 1 is high, for example, as shown in Figure 5 of (a), Figure 5 of (b), the baffle 5 is in the open state. In this case, air flows in both the first flow path 3a and the second flow path 3b, and an appropriate amount of fuel gas corresponding to the air flow rate can flow out from both the first fuel gas outlet 80a and the second fuel gas outlet 80b. Therefore, the regulation ratio can be increased.

[0096] The baffle 5 not only opens and closes the first flow path 3a but also opens and closes the first fuel gas outlet 80a. Therefore, for example, when the first flow path 3a is set to the closed state, the first fuel gas outlet 80a also simultaneously becomes the closed state, thus appropriately preventing an abnormal situation where fuel gas unnecessarily flows out from the first fuel gas outlet 80a thereafter. As a mechanism for achieving such an object, a total of two baffles for the first flow path 3a and the first fuel gas outlet 80a are not used, so the overall structure of the premixing device A can be simplified and the manufacturing cost can be reduced.

[0097] The first fuel gas flow path 8a and the second fuel gas flow path 8b communicate with each other via the fuel gas receiving portion 81. Therefore, originally, when the baffle 5 changes from the closed state to Figure 6 the small open state shown in (a) to Figure 6 the (c) shown, there is a risk of air backflow in which the air in the first flow path 3a flows toward the fuel gas outlet 80a due to the negative pressure generated in the second flow path 3b. However, according to the present embodiment, a pair of protruding wall portions 45 obstruct the flow of the air. Therefore, the air backflow phenomenon is suppressed, and an inappropriate mixing ratio in which the mixture becomes fuel-lean can be appropriately prevented.

[0098] Although a pair of protruding wall portions 45 are provided at both edges in the x direction of the peripheral portion of the first fuel gas outlet 80a, protruding wall portions 45 and similar portions are not provided at both edges 46 in the y direction (refer to Figure 7 of (a), Figure 7(b)). Therefore, when the baffle 5 is in the small opening state, the air in the first flow path 3a can flow toward the two edge portions 46 in the y direction of the first fuel gas outlet 80a and travel downstream of the first flow path 3a. As a result, the negative pressure generated by the air flow can be utilized to appropriately discharge the fuel gas from the first fuel gas outlet 80a into the first flow path 3a. It is possible to appropriately avoid the situation where the fuel gas outflow amount tends to be insufficient when the baffle 5 is in the small opening state due to the presence of the pair of protruding wall portions 45.

[0099] Furthermore, when the baffle 5 changes from the closed state to the open state, the effective flow path area of the premixing flow path 3 changes rapidly (rapidly expands). Therefore, originally, there is a risk that the flow velocity of the air flow in the second flow path 3b decreases rapidly and the air-fuel mixture changes rapidly to a fuel-lean mixture ratio. However, in the present embodiment, when the baffle 5 changes from the closed state to the open state, the pair of protruding wall portions 45 generates air resistance in the first flow path 3a. As a result, when the baffle 5 changes from the closed state to the open state, it is possible to avoid a rapid decrease in the flow velocity of the air flow that has been generated in the second flow path 3b. As a result, it is possible to more appropriately suppress the air-fuel mixture ratio from becoming an inappropriate fuel-lean mixture ratio.

[0100] On the other hand, the size of the pair of protruding wall portions 45 is such that when the baffle 5 is in a specified small opening state, it can enter the hole portion 55 of the baffle 5, but when the opening degree of the baffle 5 is greater than the specified small opening state, it can escape from the hole portion 55. Therefore, when the opening degree of the baffle 5 is large, it is possible to appropriately avoid the air resistance of the pair of protruding wall portions 45 from becoming too large, thereby reducing the pressure loss.

[0101] The present invention is not limited to the content of the above-described embodiment. Various design changes can be freely made to the specific structures of the respective parts of the premixing device and the combustion device of the present invention within the range intended to be achieved by the present invention.

[0102] The premixing flow path is preferably in the shape of a Venturi, but is not limited thereto.

[0103] The specific shapes, sizes, materials, etc. of the first blade portion, the second blade portion, the baffle, the protruding wall portion, etc. are not limited to the above-described embodiment. The first fuel gas outlet and the second fuel gas outlet may not be provided one each, but may be provided, for example, a plurality each. The shape, size, number, arrangement, etc. of the protruding wall portion can be appropriately changed corresponding to the specific structure of the first fuel gas outlet. The protruding wall portion may be provided with at least one in a manner located between the first flow path and the first fuel gas outlet, and may not necessarily be provided in a pair.

[0104] The hole portion for avoiding interference between the baffle and the protruding wall portion may not be a through-hole shape. For example, it may be configured as a concave portion (non-through-hole shape) having a depth greater than the height of the protruding wall portion and capable of allowing the protruding wall portion to enter. In the present invention, it is only necessary that the baffle and the protruding wall portion are in a relationship that can avoid interference with each other when the baffle is in an open state below a specified opening degree, and there is no limitation on the specific means for this purpose.

[0105] As a method for enabling the baffle to swing, for example, the following method can be used instead of using a shaft body made of metal or the like of a different individual from the baffle: a convex portion that functions as a swing center of the baffle is provided in one of the baffle or the support member of the baffle, and a concave portion or the like for embedding the convex portion is provided in the other. Furthermore, it can also be configured such that, for example, the baffle is swung by the driving force of a motor.

[0106] The fuel gas is, for example, natural gas or liquefied petroleum (LP) gas, but the specific type is not limited. The combustion device of the present invention is not limited to being used for a hot water device. For example, it can also be used as a combustion device for other purposes such as heating or incineration. In addition, it is not limited to the type in which the combustion gas travels downward, and it can also be configured such that the combustion gas travels upward, for example.

Claims

1. A premixing device comprising: a premixing flow path to which air is supplied from the outside and for mixing fuel gas with the air to generate a mixed gas; a partition wall portion that divides the premixing flow path into a first flow path and a second flow path that are arranged in parallel; and The first fuel gas outflow port and the second fuel gas outflow port can use the negative pressure generated by the air flow in the first flow path and the second flow path to make the fuel gas flow out to the first flow path and the second flow path. The premixing device is characterized in that it comprises: a first blade portion provided in the first flow path and provided with the first fuel gas outflow port in a manner facing the downstream side in the air flow direction; a protruding wall portion provided on the first blade portion so as to protrude from an edge of the first fuel gas outflow port toward a downstream side in the air flow direction; and The baffle is located at a position in the first flow path that is more downstream than the first blade portion in the air flow direction, and is swung in a direction opposite to the first blade portion, and is capable of opening and closing the first flow path and the first fuel gas outlet together according to the air flow rate of the premixing flow path while avoiding interference with the protruding wall portion, and is configured as follows: When the damper is in an open state with an opening degree equal to or less than a predetermined degree, the protruding wall portion can suppress the air in the first flow path from flowing toward the first fuel gas outflow port.

2. The premixing device according to claim 1, wherein As a mechanism for avoiding interference between the shutter and the protruding wall, the shutter is provided with a hole into which the protruding wall enters when the shutter is in an open state with an opening degree equal to or less than the predetermined degree.

3. The premixing device according to claim 2, wherein The protruding wall portion has a height such that the protruding wall portion protrudes from the hole portion of the shutter when the shutter is in an open state larger than the predetermined opening degree.

4. The premixing device according to claim 3, wherein The hole portion of the baffle is in the shape of a long hole extending in a specific direction from the base end side close to the swing center of the baffle to the front end side. The protruding wall portion is in a rib shape extending in a direction corresponding to the specific direction, and a planar or curved chamfered portion is provided at a corner of a front end portion of the protruding wall portion on a side away from a swing center of the baffle.

5. The premixing device according to claim 1, wherein The protruding wall portion extends in a series along the first fuel gas outflow port, and has a length substantially the same as that of the first fuel gas outflow port.

6. The premixing device according to claim 1, wherein As directions intersecting the air flow direction, there are x-direction and y-direction intersecting with each other. The first blade portion extends in the y direction in a manner spanning between a portion and another portion of the inner wall of the first flow path, thereby dividing a portion of the first flow path into a pair of divided flow paths, and in the x direction, the first blade portion and the first fuel gas outlet are located between the pair of divided flow paths. The protruding wall portion includes a pair of protruding wall portions located at both edge portions of the first fuel gas outflow port in the x direction.

7. The premixing device according to claim 6, comprising: The protruding wall portion may not be provided at both edges of the first fuel gas outlet in the first blade portion in the y direction, and when the damper is in an open state below the predetermined opening degree, the air in the first flow path flows toward both edges of the first fuel gas outlet in the y direction.

8. The premixing device according to claim 1, further comprising: a premixing flow path forming member, forming the premixing flow path; a second blade portion, one end of which is connected to the peripheral wall portion of the premixing flow path forming member and the other end of which is connected to the first blade portion via the partition wall portion, and is provided in the second flow path, and the second fuel gas outflow port is provided toward the downstream side of the air flow direction; a fuel gas receiving portion provided on the peripheral wall portion of the premixing flow path forming member and receiving a supply of fuel gas from the outside; a second fuel gas flow path provided in the second blade portion so as to guide a part of the fuel gas supplied to the fuel gas receiving portion to the second fuel gas outflow port; and The first fuel gas flow path is extended from the second blade portion into the first blade portion so as to guide another part of the fuel gas supplied to the fuel gas receiving portion to the first fuel gas outflow port.

9. A combustion device, comprising: Fan; A premixing device is provided on the air inlet side of the blower and generates a mixed gas by mixing air and fuel gas and sends the mixed gas to the blower; as well as a burner unit that receives the mixed gas from the blower and burns the fuel gas, The combustion device is characterized in that As the premixing device, the premixing device according to any one of claims 1 to 8 is used.

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