PREMIXING DEVICE AND COMBUSTION DEVICE INCLUDING THE SAME

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serial no. 2024-010830, filed on Jan. 29, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The invention relates to a premixing device and a combustion device including the same. Here, “premixing” refers to a process of mixing air and a fuel gas in advance to generate a combustible gas mixture for the purpose of performing premixing combustion.

Description of Related Art

Patent Document 1 discloses as a specific example of a premixing device. The premixing device disclosed in the same document includes a premixing flow path forming member. The premixing flow path forming member allows air to flow from an end side toward the other end side and forms a premixing flow path for mixing a fuel gas with the air. A base part to which a pipe joint part for connecting a gas pipe is attached is provided in the premixing flow path forming member. The fuel gas supplied from the gas pipe to the pipe joint part passes through a predetermined fuel gas flow path and arrives at a fuel gas outlet as a terminal thereof, and flows to the premixing flow path. Accordingly, a gas mixture of the fuel gas and air is generated in the premixing flow path and supplied to the downstream side of the premixing device.

The fuel gas includes, for example, two types, i.e., natural gas and LP gas. Since the two types of fuel gas have different components and heating values, it is necessary for the premixing device to correspond to the type of fuel gas. That is, assuming that the negative pressure generated in the premixing flow path is the same, it is necessary to set the outflow rate from the fuel gas outlet to the premixing flow path to be higher for a fuel gas with a smaller heating value than a fuel gas with a greater heating value.

Therefore, in Patent Document 1, a predetermined flow path adjustment member is directly or indirectly attached to the premixing flow path forming member, a flow path resistance of the fuel gas flow path is changed by changing the attachment mode, and the flow path resistance can be set appropriately according to the type of fuel gas. With such configuration, it is possible to suitably cope with multiple types of fuel gas.

However, in the conventional technology, there is still room for improvement as described below.

That is, there is a demand to perform, as soon and as easily as possible, the process of changing the flow path adjustment member in accordance with the type of fuel gas. Since the process may be performed on-site at where a hot water supply device including the premixing device is disposed, the demand is even stronger. Therefore, compared with Patent Document 1, it is desired to further improve the operability of the process for coping with the type of the fuel gas. Of course, care must be taken so that suitable sealing properties are secured and undue fuel gas leakage must not occur.

PRIOR ART DOCUMENT(S)

Patent Document(s)

• [Patent Document 1] Japanese Patent No. 7385804
• [Patent Document 2] Japanese Patent No. 5373671
• [Patent Document 3] Japanese Patent No. 2857352
• [Patent Document 4] Japanese Patent Application Laid-open No. S52-159434
  The invention provides a premixing device and a combustion device including the same, which are able to easily, quickly, and appropriately cope with the types of fuel gas.

SUMMARY

A premixing device provided according to a first aspect of the invention includes: a premixing flow path forming member, forming a premixing flow path for causing air to flow from an end side to an other end side and mixing a fuel gas with the air; a base part, provided at the premixing flow path forming member, and provided to be attached by a pipe joint part with which a gas pipe is connected, the gas pipe being provided for supply of the fuel gas; a fuel gas flow path, in which a terminal part is formed as a fuel gas outlet for the fuel gas to flow out to the premixing flow path and which is provided to guide the fuel gas having been supplied to the pipe joint part to the fuel gas outlet; a flow path adjustment member, having an opening part forming a portion of the fuel gas flow path, the opening part being set with an opening area corresponding to a type of the fuel gas; and a seal member, provided to seal an attachment position of the flow path adjustment member. In the premixing device, as a portion opposite to the flow path adjustment member, a first wall surface of the fuel gas flow path in which a portion is open is provided at the base part, the flow path adjustment member has, on a second wall surface part on a rear surface side of the flow path adjustment member, a claw part able to hold the seal member, and the pipe joint part is able to be attached to the base part in a state in which the flow path adjustment part is sandwiched, so that the seal member is sandwiched and pressurized by the first wall surface part and the second wall surface part.

A combustion device provided by the second aspect of the invention includes the premixing device provided by the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an example of a combustion device including a premixing device according to the invention.

FIG. 2 is a perspective view illustrating the appearance of the premixing device of FIG. 1.

FIG. 3 is an exploded perspective view of FIG. 2.

FIG. 4A is a front cross-sectional view illustrating the premixing device shown in FIG. 2, and FIG. 4B is an exploded cross-sectional view thereof.

FIG. 5A is a plan cross-sectional view illustrating main components of the premixing device as shown in FIG. 2, and FIG. 5B is an exploded cross-sectional view thereof.

FIG. 6A is a cross-sectional view illustrating the premixing device shown in FIG. 2 at a position different from FIG. 4A, and FIG. 6B is a cross-sectional view taken along a line VIb-VIb of FIG. 6A.

FIG. 7A is a plan view of the premixing flow path forming member of the premixing device shown in FIG. 2, FIG. 7B is an enlarged view of main components, and FIG. 7C is a plan cross-sectional view of FIG. 7A.

FIG. 8A is a perspective view illustrating an assembly in which a flow path adjustment member and a seal member of the premixing device shown in FIG. 2 are assembled, and FIG. 8B is an exploded perspective view of FIG. 8A.

FIG. 9A is a perspective view illustrating the assembly shown in FIG. 8A from a different perspective, and FIG. 9B is an exploded perspective view of FIG. 9A.

FIG. 10A is a plan cross-sectional view of the assembly shown in FIGS. 8A to 9B, and FIG. 10B is an exploded cross-sectional view of FIG. 10A.

FIG. 11A is a longitudinal cross-sectional view of the assembly shown in FIGS. 8A to 9B, and FIG. 11B is an exploded cross-sectional view of FIG. 11A.

FIG. 12A is a schematic front view illustrating a base part and a pipe joint part of the premixing flow path forming member shown in FIGS. 2 and 3, and FIG. 12B and FIG. 12C are schematic front views illustrating a state where the pipe joint part is attached to the base part.

FIG. 13 is a cross-sectional view of main components, which illustrates an example of a solution for a case where a seal member is stuck to the base part of the premixing flow path forming member shown in FIGS. 2 and 3.

FIG. 14A is a plan cross-sectional view illustrating another example of the assembled product of the flow path adjustment member and the seal member of the premixing device, and FIG. 14B is a longitudinal cross-sectional view of FIG. 14A.

FIG. 15 is an exploded perspective view illustrating another example of the flow path adjustment member and the seal member of the premixing device.

DESCRIPTION OF THE EMBODIMENTS

A premixing device provided according to a first aspect of the invention includes: a premixing flow path forming member, forming a premixing flow path for causing air to flow from an end side to an other end side and mixing a fuel gas with the air; a base part, provided at the premixing flow path forming member, and provided to be attached by a pipe joint part with which a gas pipe is connected, the gas pipe being provided for supply of the fuel gas; a fuel gas flow path, in which a terminal part is formed as a fuel gas outlet for the fuel gas to flow out to the premixing flow path and which is provided to guide the fuel gas having been supplied to the pipe joint part to the fuel gas outlet; a flow path adjustment member, having an opening part forming a portion of the fuel gas flow path, the opening part being set with an opening area corresponding to a type of the fuel gas; and a seal member, provided to seal an attachment position of the flow path adjustment member. In the premixing device, as a portion opposite to the flow path adjustment member, a first wall surface of the fuel gas flow path in which a portion is open is provided at the base part, the flow path adjustment member has, on a second wall surface part on a rear surface side of the flow path adjustment member, a claw part able to hold the seal member, and the pipe joint part is able to be attached to the base part in a state in which the flow path adjustment part is sandwiched, so that the seal member is sandwiched and pressurized by the first wall surface part and the second wall surface part.

According to the configuration, as the flow path adjustment member, by using the flow path adjustment member in which the opening part with the opening area corresponding to the type of the fuel gas is provided, the flow path resistance of the fuel gas flow path can be adapted to the fuel gas. In addition to such effect, effects as follows can be further attained.

That is, in the attached state of the flow path adjustment member, the seal member is sandwiched and pressurized by the predetermined first wall surface part of the base part and the second wall surface part on the rear surface side of the flow path adjustment member, and excellent seal properties are attained for such portion. Therefore, the reliability in terms of preventing fuel gas leakage can be increased.

Since it is possible to hold the seal member by using the claw part of the flow path adjustment member, the seal member and the flow path adjustment member can be handled as a single unit, and the process of attaching and removing the components to and from the premixing flow path forming member is simplified.

The attachment of the flow path adjustment member to the premixing flow path member can be performed by sandwiching the flow path adjustment member therebetween when the pipe joint part is attached to the base part of the premixing flow path forming member. Therefore, the process of attaching the flow path adjustment member is further simplified, and, likewise, the removal process is further simplified as well.

In the invention, it may also be that the flow path adjustment member includes: a body member, including a tubular wall part and the claw part. An inner region of the tubular wall part forms a portion of the fuel gas flow path, and the claw part is protrusively provided on an end side of the tubular wall part; and an auxiliary member, overlapped with the end side of the tubular wall part and having the opening part, the second wall surface part, and a hole part or a notch part through which the claw part is inserted, and the seal member is overlapped with the second wall surface part of the auxiliary member so as to sandwich the auxiliary member with the body member, and is engaged with an engagement part provided at a tip end side of the claw part.

According to such configuration, effects as follows are obtained.

That is, by combining the components in the state in which the auxiliary member, the seal member, and the body member of the flow path adjustment member are overlapped, it is possible to handle the components as a single unit, and it is possible to improve the attachment and removal operability. Here, for example, in an inappropriately assembled state in which only one of the auxiliary member and the seal member is overlapped with the body member and the other is not overlapped, the one of the auxiliary member and the seal member is not fixed to the body member. Therefore, the operator intending to attaching the flow path adjustment member and the seal member is able to easily detect such issue, and the concern that the flow path adjustment member is attached to the base part while the seal member remains missing is resolved.

In the invention, it may also be that the flow path adjustment member includes a tubular wall part in which an inner region forms a portion of the fuel gas flow path, and the second wall surface part on which the opening part is provided and the claw part are integrally formed on the tubular wall part.

According to such configuration, when compared with a component formed by two components, such as the body member and the auxiliary member, the number of parts of the flow path adjustment member can be decreased. Therefore, in addition to further simplifying the handling, it is also possible to reduce the manufacturing cost.

In the invention, it may also be that a first concave part having an opening shape on a front surface is provided at the base part, and the flow path adjustment member is able to be set to a state in which a rear side portion thereof is fit in the first concave part, and in a state in which the pipe joint part is removed from the base part, a front side portion of the flow path adjustment member is configured to protrude outwardly toward a front side of the base part.

According to the configuration, at the time of attaching the flow path adjustment member to the base part, the rear side portion of the flow path adjustment member can enter the first concave part to be supported. Therefore, in the state, it suffices as long as the pipe joint part is attached to the base part. Accordingly, the process of attaching the flow path adjustment member and the pipe joint part is further simplified. In addition, in the state in which the flow path adjustment member and the pipe joint part are attached to the base part, the front side portion of the flow path adjustment member protrudes outwardly toward the front side of the base part. Therefore, by grasping such protrusion part, the entirety of the flow path adjustment member can be easily pulled out from the first concave part.

In the invention, it may also be that a second concave part into which the claw part is able enter is provided on the first wall surface part of the base part.

According to the configuration, in the attached state of the flow path adjustment member, the inappropriate interference between the claw part thereof and the base part of the first wall surface part can be avoided, and it is easily made possible that the claw part does not become an obstacle when the seal member is brought into contact with the first wall surface part. In addition, as described with reference to FIG. 13 in the following, in the case where the seal member is stuck to the first wall surface part, the second concave part can be used as a concave part with which the tool for peeling off the seal member is inserted.

In the invention, it may also be that the premixing device further includes a partition wall part, partitioning the premixing flow path into first and second flow paths into parallel arrangement, and the fuel gas flow path is branched into a first fuel gas flow path and a second fuel gas flow path, and the first fuel gas flow path and the second fuel gas flow path are provided with, as the fuel gas outlet, a first fuel gas outlet and a second fuel gas outlet through which the fuel gas is able to flow to the first flow path and the second flow path, and as the opening part of the flow path adjustment member, a first opening part and a second opening part corresponding to the first fuel gas flow path and the second fuel gas flow path are provided.

According to the configuration, it is possible for both of the first fuel gas path and the second fuel gas path for supplying fuel gas to the first flow path and the second flow path of the premixing flow path to appropriately cope with the types of fuel gas.

In the invention, it may also be that the flow path adjustment member includes a tubular wall part in which an inner region forms a portion of the fuel gas flow path, and as the opening part of the flow path adjustment member, a third opening part located upstream of the first opening part and the second opening part in a fuel gas flow direction, and the fuel gas passing through the third opening part is configured to travel to the first opening part and the second opening part.

According to the configuration, the respective flow path resistances of the first flow path and the second flow path can be further controlled by the third opening part in addition the first opening part and the second opening part of the flow path adjustment member. Therefore, it is possible to exert control more precisely.

A combustion device provided by the second aspect of the invention includes the premixing device provided by the first aspect of the invention.

Other features and advantages of the invention will become more apparent from the description of the embodiments of the invention to be given below with reference to the attached drawings.

The following describes exemplary embodiments of the invention with reference to the drawings.

FIG. 1 shows a hot water apparatus WH. The hot water apparatus WH is a hot water supply apparatus, and includes a premixing device A, a combustion device B (premixing combustion device), and a heat exchanger 11. The combustion device B is configured by combining a fan 1 and a burner part 12 in the premixing device A. The fan 1 is variable in speed (variable in air flow rate).

The details of the premixing device A will be described later. However, a gas mixture (combustible gas mixture) of air and a fuel gas is generated by using the premixing device A, and the gas mixture is supplied to the burner part 12 via the fan 1. The burner part 12 includes a porous plate 12a having multiple air holes 12b (flame holes) and is accommodated in a case 10. The burner part 12 is provided with accessories such as an ignition plug and a flame detection sensor, which are not shown. The gas mixture passes through the air holes 12b and causes combustion below the porous plate 12a. The combustion gas generated by the burner part 12 acts on the heat exchanger 11, and the water passing through the heat exchanger 11 is heated. As a result, hot water is generated, and the hot water is supplied to the desired hot water supply destination.

As well shown in FIG. 2 to FIG. 6B, the premixing device A includes a device body part A0 and a flapper 5, a flow path adjustment member 2, and a seal member 7 attached to the device body part A0.

In the figures, x and y directions intersect each other, and also intersect the air flow direction (upward) in the premixing flow path 3 to be described afterwards.

The device body part A0 includes a premixing flow path forming member 4 and a pipe joint part 9.

The premixing flow path forming member 4 includes a tubular part 49, an attachment flange part 48, a base part 44, and a fuel gas flow path 8. A venturi-shaped premixing flow path 3 is formed inside the tubular part 49. The attachment flange part 48 is connected to the upper end of the tubular part 49.

The pipe joint part 9 is a portion connected with a gas pipe 99 (see FIG. 1) and receives the supply of the fuel gas. The pipe joint part 9 includes a tubular part 94 and an attachment flange part 95. In the tubular part 94, a hollow part that serves as the initial part of the fuel gas flow path 8 is formed. The attachment flange part 95 is connected with the proximal end of the tubular part 94.

The base part 44 is a portion to which the pipe joint part 9 is attached, and has a pedestal shape or a shape similar thereto integrally provided on the outer peripheral part of the tubular part 49. The base part 44 includes a flange part 44a corresponding to the flange part 95 of the pipe joint part 9. In a state where the flange parts 95, 44a are opposite to and in contact with each other, the attachment of the pipe joint part 9 to the base part 44 can be achieved by fastening the components by using a screw member 90 such as a screw.

Gas type display parts 98a, 98b indicating the types of fuel gas supplied to the premixing device A are provided on the flange part 44a of the base part 44. The gas type display parts 98a, 98b are, for example, the text “NG” and “LP”, respectively, the former indicating natural gas and the latter indicating LP gas.

The flange part 95 of the pipe joint part 9 is in a non-circular shape when viewed in a front view, and, as will be described in the following, the flange part 95 can be set to selectively hide one of the gas type display parts 98a, 98b and not hide the other.

That is, the pipe joint part 9 and the base part 44 are configured as shown in FIG. 12A when viewed in the front view. When the pipe joint part 9 is attached to the base part 44 in the orientation shown in the same figure, as shown in FIG. 12B, the text “LP” of the gas type display part 98b is hidden by the pipe joint part 9 and the text “NG” of the gas type display part 98a is not hidden. In the case where the fuel gas is natural gas, such state may be set. Differing from this, when the pipe joint part 9 is reversed up-side-down from the above, as shown in FIG. 12C, the text “NG” of the gas type display part 98a is hidden by the pipe joint part 9 and the text “LP” of the gas type display part 98b is not hidden. In the case where the fuel gas is LP gas, such state may be set.

As shown in FIG. 1, in the premixing device A, the pipe joint part 9 is connected to the gas pipe 99, and the premixing device A receives the supply of fuel gas from a fuel gas supply source (not shown) via a pressure-equalizing (zero governor) valve V1. On the other hand, the premixing device A is directly or indirectly connected to the intake side of the fan 1 by using the 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 inside the tubular part 49). Due to the negative pressure effect generated by the flow of the air, the fuel gas flows out from the first and second fuel gas outlets 80a, 80b to be described later, and a gas mixture of the fuel gas and the air is generated. The gas mixture is supplied to the burner part 12 via the fan 1.

As well shown in FIG. 6A and FIGS. 7A to 7C, a partition wall part 40 extending in the upper-lower height direction along the air flow direction is provided in the premixing flow path 3. As a result, a portion of the premixing flow path 3 is divided into first and second flow paths 3a, 3b arranged in the y direction by sandwiching the partition wall part 40.

As well shown in FIG. 4A to FIG. 7C, first and second blade parts 41a, 41b (shown as dotted pattern portions in FIGS. 7A and 7C) are provided in the first and second flow paths 3a, 3b. On the upper surface parts facing the downstream side in the air flow direction in the first and second blade parts 41a, 41b, first and second fuel gas outlets 80a, 80b are provided as upward-facing openings.

The first and second blade parts 41a, 41b extend in the y direction to traversely cross the first and second flow paths 3a, 3b in the horizontal direction, respectively. An end of each of the first and second blade parts 41a, 41b is connected to a peripheral wall inner surface part of the premixing flow path 3 (the inner surface part of the peripheral wall part of the tubular part 49), and the other ends of the first and second blade parts 41a, 41b are connected to each other by sandwiching the partition wall part 40.

As well shown in FIGS. 7A to 7C, a portion of the first flow path 3a is divided into a pair of regions 3a sandwiching the first blade part 41a in the x direction. A portion of the second flow part 3b is divided into a pair of regions 3b sandwiching the second blade part 41b in the x direction.

The fuel gas flow path 8 is a flow path in which the inside of the tubular part 94 of the pipe joint part 9 serves as the initial part and the first and second fuel gas outlets 80a, 80b serve as the end part. In the fuel gas flow path 8, first and second opening parts 22a, 22b, which will be described in the following, of the flow path adjustment member 2 are set as a branching part, and the portion downstream thereof is branched into first and second fuel gas flow paths 8a, 8b. The first and second fuel gas flow paths 8a, 9b are formed inside the base part 44 and inside the first and second blade parts 41a, 41b.

The fuel gas supplied to the pipe joint part 9 is guided to the first and second fuel gas outlets 80a, 80b through the first and second opening parts 22a, 22b of the flow path adjustment member 2 and the first and second fuel gas flow paths 8a, 8b.

In the lower and upper parts inside the tubular part 49, an air inlet part 3c and an air outlet part 3d are formed. The air inlet part 3d and the air outlet part 3d are in communication with the first and second flow paths 3a, 3b. When the fan 1 is driven, the air from the outside can flow into the air inlet part 3c and then be branched and flow into the first and second flow paths 3a, 3b. Due to the negative pressure effect generated by the air flow in the first and second flow paths 3a, 3b, fuel gas flows out from the first and second fuel gas outlets 80a, 80b, and a gas mixture of air and fuel gas is generated. The gas mixture flows out from the air outlet part 3d to the outside of the tubular part 49.

As shown in FIG. 4A to FIG. 6B, the flapper 5 is capable of simultaneously opening and closing the first flow path 3a (the pair of regions 3a′) and the first fuel gas outlet 80a. The flapper 5 is a resin molded product, for example, the proximal end of the flapper 5 is supported by a support part 52 using a shaft body 61, and the flapper 5 is able to swing in the upper-lower height direction by using a center line CL thereof. As well shown in FIG. 3, the shaft body 61 is a portion supported by a pair of auxiliary members 60 having support hole parts 60a. The pair of auxiliary members 60 are attached to a step part 43 provided separately in the first flow path 3a by using screw members 92, etc.

The flapper 5 swings by using the self-weight as a downward force and the upward air flow through the first flow path 3a as an upward force. In the case where the air flow rate of the premixing flow path 3 is low, the opening degree decreases. In the case where the air flow rate is low, the flapper 5 lies down horizontally due to the self-weight and becomes closed, and when the air flow rate increases, the flapper 5 is held upward due to the upward air flow and becomes open. In the flapper 5, a pair of fins 55 are protrusively provided as appropriate. The pair of fins 55 are located to sandwich the first blade part 41a when the flapper 5 is in the closed state.

The flow path adjustment member 2 is a member that controls the flow path resistance of each of the first and second fuel gas flow paths 8a, 8b and controls, to a flow rate corresponding to the type of fuel gas, the fuel gas flow rate toward the first and second fuel gas outlets 80a and 80b.

As well shown in FIG. 8A to 11b, the flow path adjustment member 2 is a component combining a body member 2a and an auxiliary member 2b.

The body member 2a includes a tubular wall part 20a, a third opening part 22c, and a pair of claw parts 23. An inner region of the tubular wall part 20a forms a portion of the fuel gas flow path 8. The third opening part 22c is provided on a front wall part 20b of the tubular wall part 20a. The pair of claw parts 23 are protrusively provided at an end part (rear wall part side) of the tubular wall part 20a. The tip end of each of the claw parts 23 is in a hook shape or a shape similar thereto, and is an engagement part 23a for holding the seal member 7.

The auxiliary member 2b includes tubular parts 24a, 24b that are short and a plate part 25. The tubular parts 24a, 24b have the first and second openings 22a, 22b. The plate part 25 is connected with the tubular parts 24a, 24b. The rear surface part of the plate part 25 is a second wall surface part S2 corresponding to a first wall surface part S1 of the base part 44 to be described afterwards. A pair of hole parts 26 to be inserted by the pair of claw parts 23 are provided on the plate part 25.

The first and second opening parts 22a, 22b of the auxiliary member 2b are portions that individually control the respective flow path resistances of the first and second fuel flow gas flow paths 8a, 8b. Comparatively, the third opening part 22c is a portion that is located upstream of the first and second opening parts 22a, 22b and controls the overall flow path resistances of the first and second fuel gas flow paths 8a, 8b. It is considered that the opening areas of all of the first to third opening parts 22a to 22c are set as areas appropriately corresponding to the types of fuel gas supplied to the premixing device A, and the flow rates of the fuel gases passing through the opening parts 22a to 22c become appropriate flow rates.

The seal member 7 is a sheet-like packing having suitable elasticity. Hole parts 74a, 74b through which the tubular parts 24a, 24b of the auxiliary member 2b are inserted and a pair of hole parts 76 through which the pair of claw parts 23 are inserted are provided on the seal member 7.

When the flow path adjustment member 2 is assembled in a state in which the auxiliary member 2b is overlapped with an end side of the body member 2a and the seal member 7 is further overlapped with the side of the second wall surface part S2 that is the rear surface part of the auxiliary member 2b, the engagement parts 23a of the pair of claw parts 23 are engaged with the peripheral parts of the hole parts 76 of the seal member 7. Accordingly, the assembled state of the body member 2a and the auxiliary member 2b of the flow path adjustment member 2 and the seal member 7 is maintained, and a flow path adjustment assembly AS in which these components are unified is prepared.

As shown in FIG. 4A to FIG. 5B, a first concave part 45a with an opening shape on the front surface (opening shape on the left side in FIGS. 4A to 5B) is provided at the base part 44 of the premixing flow path forming member 4. The first concave part 45a is a portion with which a rear side portion of the flow path adjustment assembly AS is fit. The wall surface part on the back side of the first concave part 45a (the wall surface part on the central side of the premixing flow path forming member 4) is the first wall surface part S1 to come into contact with the seal member 7 when the assembly AS is fit with the first concave part 45a. As well shown in FIG. 5B, a pair of second concave parts 45b which the pair of claw parts 23 are able to enter are provided on the first wall surface part S1, and inappropriate interference between each claw part 23 and the first wall surface part S1 is avoided.

In the state in which the rear side portion of the flow path adjustment assembly AS is fit with the first concave part 45, the front side portion of the assembly AS protrudes forward of the first concave part 45a. Comparatively, the pipe joint part 9 has a third concave part 9a with which the front side portion of the assembly AS is able to fit. As well shown in FIGS. 4A and 5A, in the state in which the pipe joint part 9 is attached to the base part 44, the flow path adjustment assembly AS is fixed and attached to the base part by being sandwiched between the pipe joint part 9 and the base part 44. In the attached state, the third opening part 22c is in communication with the inside of the pipe joint part 9. In addition, the tubular parts 24a, 24b forming the first and second opening parts 22a, 22b are in a state of entering the tip opening portions of the first and second fuel gas flow paths 8a, 8b. The seal member 7 is sandwiched and pressurized by the first wall surface part S1 and the second wall surface part S2 opposite to each other.

Then, the operation of the premixing device A and the combustion device B including the premixing device A will be described.

In the premixing device A, the flow path adjustment assembly AS in which the flow path adjustment member 2 and the seal member 7 are assembled is provided. The first to third opening parts 22a to 22c of the assembly AS are set with opening areas corresponding to the types of fuel gas actually supplied to the premixing device A. Therefore, it is possible to adapt the fuel gas flow rate of the fuel gas flow path 8 to the type of fuel gas by controlling the flow path resistance of the fuel gas flow path 8 (the first and second fuel gas flow paths 8a, 8b). Therefore, it is possible to set the air-fuel ratio of the gas mixture to a ratio adapted in correspondence with the type of fuel gas, and the combustion properties of the burner part 12 can be favorable. In addition to such effect, effects as follows can be further attained.

That is, in the attached state of the flow path adjustment assembly AS, the seal member 7 is sandwiched and pressurized by the first wall surface part S1 of the base part 44 and the second wall surface part S2 of the flow path adjustment member 2, and excellent seal properties are attained for such portion. Therefore, it is possible to increase the reliability in terms of preventing fuel gas leakage.

The flow path adjustment member 2 and the seal member 7 can be handled in a unified state as the flow path adjustment assembly AS, and the attachment process to the base part 44 or the removal process of the premixing flow path forming member can be performed at once. Differing from the embodiment, when the flow path adjustment member 2 and the seal member 7 remain separated, for example, it is necessary to attach the components to the base part 44 in order, and the process becomes complicated. Comparatively, according to the embodiment, the process is convenient without such complexity.

For assembling the flow path adjustment member 2 and the seal member 7 as the assembly AS, it suffices as long as the three components, i.e., the body member 2a and the auxiliary member 2b of the flow path adjustment member 2 and the seal member 7 are overlapped, and the process is also easy. Although it is necessary to respectively insert the pair of claw parts 23 into the hole parts 26 of the auxiliary member 2b and the hole parts 76 of the seal member when the three components are overlapped, such process is also easy. In addition, at the time of performing such process, the engagement parts 23a of the pair of claw parts 23 are automatically engaged with the seal member 7, and the assembled state of the three components is maintained. Since the three components are not easy to separate, it is possible to further improve the handling properties of the assembly AS.

For example, in the case where the three components are not appropriately overlapped, such as that the seal member 7 is not appropriately overlapped, due to the operator's negligence, for example, the assembly As of the flow path adjustment member 2 is not produced appropriately, and the body member 2a and the auxiliary member 2b of the flow path adjustment member 2 are merely brought close in a disjointed state. That is, in the case where the three components are not appropriately assembled, the three components are not neatly overlapped. Therefore, it is easy for the operator to notice such issue, and the concern of being attached to the base part 44 when the flow path adjustment member 2 or the seal member 7 remain inappropriate or, for example, the seal member 7 remains missing can be resolved.

In the case where the flow path adjustment assembly AS is attached to the base part 44 of the premixing flow path forming member 4, it is not necessary to screw the assembly AS to the base part 44 alone, and the attachment of the assembly AS can be completed at the same time through the process of attaching the pipe joint part 9 to the base part 44. Therefore, the process of attaching the flow path adjustment assembly AS to the base part 44 and the removal process thereof can be performed efficiently.

At the time of attaching the assembly AS to the base part 44, it suffices as long as the rear side portion of the assembly AS is fit with the first concave part 45a and held temporarily, and the pipe joint part 9 is attached to the base part 44, so the process is further simplified. In the case of removing the assembly AS from the base part 44, if the pipe joint part 9 is previously removed from the base part 44, the front side portion of the assembly AS protrudes toward the front thereof from the first concave part 45a of the base part 44. Therefore, it is possible to grasp the protruding portion and easily take out the assembly AS from the first concave part 45a.

In the case where the premixing device A is actually used, the type of fuel gas may be changed to a fuel gas different from the fuel gas set originally. In such case, in the field where the premixing device A is set, for example, it is necessary to replace the flow path adjustment member 2 to a different flow path adjustment member corresponding to the fuel gas after change. Comparatively, in the embodiment, as described above, it is easy to attach and remove the flow path adjustment member 2. Therefore, the embodiment is also suitable for such case.

The seal member 7 is a member firmly pressed to and brought into contact with the first wall surface part S1 of the base part 44. Therefore, as shown in FIG. 13, even if the body member 2a or the auxiliary member 2b of the flow path adjustment member 2 is removed from the base part 44, the seal member 7 may remain in close contact with the first wall surface S1. In such case, it suffice as long as a tool 87 for peeling off the seal member 7 is inserted into the second concave part 45b from the hole part 76 to contact the opening peripheral part on the back side of the hole part 76 of the seal member 7 and peel off the seal member 7. The second concave part 45 can also be used for such purpose.

In the premixing device A, in the case where the driving speed of the fan 1 is low and the air flow rate in the premixing flow path 3 is low, as shown in FIGS. 4A to 4B, the flapper 5 is in the closed state, and the air flows toward the second flow path 3b with the first flow path 3a in the blocked state. Therefore, the air flow in the second flow path 3b can be accelerated, a strong negative pressure acts on the second fuel gas outlet 80b, and an appropriate amount of fuel gas corresponding to the air flow rate can be discharged to the second flow path 3b. Meanwhile, when the driving speed of the fan 1 is high, the flapper 5 is in the open state, the air flows sufficiently into both the first and second flow paths 3a, 3b, and an appropriate amount of fuel gas corresponding to the air flow rate can be discharged from both the first and second fuel gas outlets 80a, 80b. As a result, the turndown ratio can be increased.

FIGS. 14A, 14B and 15 illustrate other embodiments of the invention. In the drawings, elements that are the same as or similar to those in the above embodiment are assigned the same reference numerals as those in the above embodiment, and repeated descriptions will be omitted.

A flow path adjustment member 2A in the embodiment shown in FIGS. 14A and 14B includes a tubular wall part 20a in which the inner region forms a portion of the fuel gas flow path 8, and the third opening part 22c is provided at a front wall part 20b of the tubular wall part 20a. In addition, at a rear wall part 25a of the tubular wall part 20a, tubular parts 24a, 24b forming the first and second opening parts 22a, 22b are provided, and a flange part 25b having the second wall surface part S2 is provided. In addition, the pair of claw parts 23 are provided at the flow path adjustment member 2.

The flow path adjustment member 2A is equivalent to the configuration in which the body member 2a and the auxiliary member 2b of the flow path adjustment member 2 of the above embodiment are integrated.

According to such configuration, the total number of parts decrease, so the cost can be reduced. In addition, the handling properties can be further improved.

In a flow path adjustment member 2B shown in FIG. 15, a notch part 26a is provided at the auxiliary member 2b, and the claw part 23 can be inserted into the notch part 26a. For the seal member 7 as well, a notch part 76a through which the claw part 23 can be inserted is provided. The notch parts 26a, 76a are components in place of the hole parts 26, 76 provided at the auxiliary member 2b and the seal member 7 of the above embodiment. In the invention, it is also possible to adopt a configuration like that of the embodiment.

The invention is not limited to the contents of the above embodiment. The specific configuration of each part of the premixing device and combustion device related to the invention can be freely modified in design within the intended scope of the invention.

In the above embodiments, it is configured that the premixing flow path is divided into the first and second flow paths, and the flapper is provided at the first flow path. However, the invention is not limited thereto. In the invention, for example, it is also possible to configure a premixing device of a type in which a flapper is not provided and the premixing flow path is not divided into multiple flow paths, as shown in Patent Document 1.

The specific shape, size, material, etc., of the flow path adjustment member can be changed in various ways. Instead of providing a pair of claw parts, it is also possible to provide a configuration with one claw part only or three or more claw parts. In addition, regarding the opening part corresponding to the type of fuel gas of the fuel gas flow path (corresponding to the first to third opening parts), it suffices as long as at least one opening part is provided. Although the opening part of the flow path adjustment member is set to an opening area corresponding to the type of fuel gas, the specific value thereof is not limited.

As the type of fuel gas, examples may include natural gas and LP gas as representative examples. However, the invention is not limited thereto, and other types of fuel gas may also be applicable. The combustion device related to the invention is not limited to a device for a hot water device, but may also be a combustion device used for other purposes such as for heating or incineration. Furthermore, it is not limited to the type where the combustion gas travels downward, but may also be of a type where the combustion gas travels upward, for example.