Gas manifold

Abstract

To simplify the production process of a gas manifold capable of adjusting the flow rate of fuel gas distributed to each of nozzle groups.SOLUTION: A body 32 formed by casting comprises a plurality of nozzles erected on the surface facing a plurality of burners, with the plurality of nozzles divided into a plurality of nozzle groups, and the opposite side surface relative to the nozzles is covered with a lid plate 40. A plurality of distribution passages 51 branched from a fuel gas supply passage to guide the fuel gas to each nozzle group are formed between the body and the lid plate. Each of the distribution passages communicates with the supply passage via an introduction port and is provided with a plurality of on-off valve opening / closing each introduction port. Each of the plurality of introduction ports is formed to have an approximately the same opening area, and at least one of the distribution passages comprises a narrowed segment 52 to regulate the flow rate of the fuel gas according to the number of nozzles included in the corresponding nozzle group. The narrowed segment is formed by a barrier 37 provided integrally with at least either of the main body and the lid plate.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a gas manifold having a plurality of nozzles that eject fuel gas toward a plurality of burners of a combustion device, the plurality of nozzles being divided into a plurality of nozzle groups, and distributing the fuel gas to each nozzle group. [Background technology]

[0002] Some combustion devices, such as water heaters, are equipped with multiple burners, and the amount of heat generated (hot water supply capacity) can be changed by switching the number of burners that burn the fuel gas. These combustion devices have multiple nozzles that spray fuel gas toward the multiple burners, and these multiple nozzles are divided into multiple nozzle groups and equipped with a gas manifold that distributes the fuel gas to each nozzle group.

[0003] A known gas manifold structure includes a cast main body with multiple nozzles protruding from a surface facing multiple burners, and a cover plate covering the surface of the main body opposite the nozzles, fastened together with a packing interposed between them. Between the main body and the cover plate, multiple distribution passages are formed, branching from a supply passage through which fuel gas is supplied and directing the fuel gas to each nozzle group. Each distribution passage communicates with the supply passage through an inlet formed in the main body, and multiple on-off valves are provided corresponding to each of the multiple distribution passages for opening and closing the inlet. Controlling the opening and closing of these on-off valves allows switching between the distribution passages (nozzle groups) that supply fuel gas from the supply passage. Furthermore, when the number of nozzles included in each nozzle group varies for each distribution passage, the flow rate of fuel gas distributed to each distribution passage (nozzle group) can be adjusted by varying the diameter of the inlet depending on the number of nozzles (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-41108 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the inlet ports in the main body of the gas manifold are generally formed by drilling after the main body has been cast, and since it is necessary to change the drill for each inlet with a different diameter, there is a problem that the manufacturing process of the gas manifold becomes complicated.

[0006] The present invention has been made in response to the above-mentioned problems in the conventional technology, and aims to provide a technology that is capable of adjusting the flow rate of fuel gas distributed to each nozzle group while simplifying the manufacturing process of a gas manifold. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the gas manifold of the present invention employs the following configuration: <First aspect> A gas manifold having a plurality of nozzles for ejecting fuel gas toward a plurality of burners of a combustion device, the plurality of nozzles being divided into a plurality of nozzle groups, the gas manifold distributing the fuel gas to each of the plurality of nozzle groups, a main body formed by casting and having the plurality of nozzles protruding from a surface facing the plurality of burners; a cover plate that covers a surface of the main body opposite to a side from which the nozzle protrudes and is fastened to the main body; a plurality of distribution passages formed between the main body and the cover plate, the distribution passages branching from a supply passage through which the fuel gas is supplied and directing the fuel gas to each of the plurality of nozzle groups; a plurality of inlets formed in the main body corresponding to the plurality of distribution passages, the inlets introducing the fuel gas from the supply passage into the plurality of distribution passages; a plurality of on-off valves that open and close each of the plurality of inlets; Equipped with regardless of the number of nozzles included in the nozzle group corresponding to each of the plurality of distribution passages, the plurality of introduction ports are all formed to have substantially the same opening area, At least one of the plurality of distribution passages has a narrowed portion that regulates the flow rate of the fuel gas in accordance with the number of the nozzles included in the corresponding nozzle group, The narrowed portion is formed by a barrier portion integrally provided on at least one of the main body and the cover plate. It is characterized by:

[0008] In the gas manifold of the first aspect, the opening areas (diameters) of the multiple inlets are substantially the same, eliminating the need to change drills when forming the multiple inlets by drilling. Furthermore, the barrier portion that forms the narrowed portion of the distribution passage can be integrally formed on at least one of the main body and the cover plate according to the number of nozzles included in the corresponding nozzle group. In particular, when the barrier portion is provided on the main body side, it can be integrally formed by casting. Furthermore, when the cover plate is formed by casting, it is possible to integrally form the barrier portion on the cover plate side by casting. This makes it possible to simplify the manufacturing process of the gas manifold while adjusting the flow rate of fuel gas distributed to each nozzle group.

[0009] <Second aspect> In the gas manifold of the first aspect, a passage wall portion that forms the plurality of distribution passages is protruded from a surface of the main body that faces the cover plate, An elastic packing is interposed between the passage wall portion of the main body and the cover plate, At the location of the distribution passage where the barrier portion is provided, the main body side and the cover plate side are in direct contact with each other without the intermediation of the packing. It is characterized by:

[0010] In the gas manifold of the second aspect, the opening area of ​​the narrowed portion formed by the direct contact between the main body side and the cover plate side at the location where the barrier portion is provided does not depend on the amount of compression of the packing. Therefore, the dimensional accuracy of the opening area of ​​the narrowed portion can be improved, making it possible to supply an appropriate flow rate of fuel gas to each nozzle group.

[0011] <Third aspect> In the gas manifold of the second embodiment, the barrier portion is provided upright on a surface of the main body facing the cover plate, The barrier portion is provided so as to protrude toward the cover plate side beyond the passage wall portion. It is characterized by:

[0012] In the gas manifold of the third aspect, even if a packing is interposed between the passage wall portion of the main body and the cover plate, the barrier portion in the narrowed portion can be directly abutted against the cover plate, so that the packing ensures the airtightness of each distribution passage while improving the dimensional accuracy of the opening area in the narrowed portion. Also, the compression amount of the packing sandwiched between the passage wall portion and the cover plate can be adjusted (kept constant) by the protrusion amount of the barrier portion. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram showing an example of a combustion device 2 mounted on a water heater 1. FIG. [Figure 2] FIG. 2 is a perspective view of the gas manifold 30 of the present embodiment as seen from the burner 10 side. [Figure 3] FIG. 2 is a perspective view showing a gas manifold 30 in an exploded state. [Figure 4] 2 is a cross-sectional view of the gas manifold 30 cut along a plane parallel to the burner 10. FIG. [Figure 5] FIG. 2 is a perspective view showing the configuration of a main body 32 in the gas manifold 30 of the present embodiment. [Figure 6] 3 is a cross-sectional view of a fourth distribution passage 51d in the gas manifold 30 of the present embodiment, taken along a plane perpendicular to the fuel gas supply direction. FIG. [Figure 7] 10 is a cross-sectional view showing another example of a barrier portion 37 erected from the bottom surface of a recess 34 in a state separate from a rib 33. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1 is an explanatory diagram showing an example of a combustion device 2 mounted on a water heater 1. The combustion device 2 has a plurality of burners 10 (19 in the illustrated example) housed in a combustion chamber 3. Furthermore, a plurality of nozzles 31 that spray fuel gas toward the burners 10 protrude from the combustion chamber 3, and is also provided with a gas manifold 30 that distributes the fuel gas to each nozzle 31, a combustion fan 5 that sends combustion air to the burners 10 from below, an ignition plug 6 that generates a spark on the burners 10 by discharging a high voltage, and a flame rod 7 that detects the flame (ignition) of the burners 10. Details of the burners 10 and the gas manifold 30 will be described later using separate drawings.

[0015] A gas passage 15 that supplies fuel gas to the gas manifold 30 is provided with a main valve 16 that opens and closes the gas passage 15, and a proportional valve 17 that adjusts the flow rate of fuel gas supplied to the gas manifold 30 downstream of the main valve 16. In the illustrated example, the multiple (19) burners 10 are divided into four burner groups, and correspondingly, as will be described later, in the gas manifold 30, four distribution passages branch off from a supply passage 50 connected to the gas passage 15 to guide fuel gas to each burner group, and the supply and cut-off of fuel gas to each distribution passage can be switched by four selector valves. That is, the gas manifold 30 is equipped with a first switching valve 18a that opens and closes the first distribution passage 51a corresponding to the first burner group 10a consisting of five burners 10, a second switching valve 18b that opens and closes the second distribution passage 51b corresponding to the second burner group 10b consisting of three burners 10, a third switching valve 18c that opens and closes the third distribution passage 51c corresponding to the third burner group 10c consisting of seven burners 10, and a fourth switching valve 18d that opens and closes the fourth distribution passage 51d corresponding to the fourth burner group 10d consisting of four burners 10.

[0016] In the combustion device 2, the amount of heat generated (hot water supply capacity) can be changed by controlling the opening and closing of four selector valves 18a, 18b, 18c, and 18d and selecting a burner group to supply fuel gas from among the four burner groups 10a, 10b, 10c, and 10d. For example, when the required amount of heat is minimal, only the second selector valve 18b corresponding to the second burner group 10b, which has the fewest number of burners 10, is opened. On the other hand, when the required amount of heat is maximum, all four selector valves 18a, 18b, 18c, and 18d are opened. When an intermediate amount of heat is required, one to three of the four selector valves 18a, 18b, 18c, and 18d are selected and opened as appropriate.

[0017] A heat exchanger 20 is provided above the combustion chamber 3. One end of the heat exchanger 20 is connected to a water supply passage 21, and the other end of the heat exchanger 20 is connected to a hot water supply passage 22. The clean water supplied through the water supply passage 21 is heated in the heat exchanger 20 by heat exchange with the combustion exhaust gas from the burner 10, and then flows out into the hot water supply passage 22 as hot water. A flow rate sensor 23 that detects the flow rate of the clean water flowing through the water supply passage 21 is provided in the water supply passage 21. When a user of the water heater 1 supplies clean water to the heat exchanger 20 by, for example, opening a faucet 24 provided in the hot water supply passage 22, the flow rate sensor 23 detects that the flow of clean water is greater than a predetermined flow rate, and combustion in the burner 10 begins.

[0018] Furthermore, an exhaust port 25 is provided above heat exchanger 20. The combustion exhaust gas generated by combustion in burner 10 is sent upward by the air blown by combustion fan 5, passes through heat exchanger 20, and is then discharged to the outside of water heater 1 from exhaust port 25.

[0019] 2 is a perspective view of the gas manifold 30 of this embodiment, viewed from the burner 10 side. As shown in the figure, the gas manifold 30 has a plurality of nozzles 31 protruding therefrom that spray fuel gas toward the burners 10. These nozzles 31 are provided in upper and lower pairs, the same number as the burners 10 (19 pairs in this embodiment). The nozzles 31 are also divided into four nozzle groups corresponding to the burners 10 being divided into four burner groups 10a, 10b, 10c, and 10d. That is, a first nozzle group 31a consisting of five sets of ten nozzles 31 corresponds to the first burner group 10a; a second nozzle group 31b consisting of three sets of six nozzles 31 corresponds to the second burner group 10b; a third nozzle group 31c consisting of seven sets of 14 nozzles 31 corresponds to the third burner group 10c; and a fourth nozzle group 31d consisting of four sets of eight nozzles 31 corresponds to the fourth burner group 10d.

[0020] Additionally, the four switching valves 18a, 18b, 18c, and 18d are provided below the four nozzle groups 31a, 31b, 31c, and 31d. As will be described in detail later, the first switching valve 18a corresponds to the first nozzle group 31a, the second switching valve 18b corresponds to the second nozzle group 31b, the third switching valve 18c corresponds to the third nozzle group 31c, and the fourth switching valve 18d corresponds to the fourth nozzle group 31d.

[0021] The burner 10 of this embodiment is formed by facing a pair of plate-like members formed by sheet metal processing, and has a flat shape. This burner 10 has a pair of upper and lower gas inlets 11 at the end on the gas manifold 30 side and a plurality of flame ports 12 at the upper end, and the gas inlets 11 and the flame ports 12 are connected by a mixing passage 13 formed between the pair of plate-like members. When the gas manifold 30 and the burner 10 are installed in the combustion device 2, the pair of upper and lower nozzles 31 of the gas manifold 30 and the pair of upper and lower gas inlets 11 of the burner 10 are arranged to face each other. Note that only one burner 10 is illustrated in FIG. 2, and the other burners 10 are not shown, but a burner 10 is installed corresponding to each pair of upper and lower nozzles 31.

[0022] 3 is a perspective view showing an exploded state of the gas manifold 30. The gas manifold 30 includes a main body 32 having a plurality of nozzles 31 protruding toward the burner 10, a cover plate 40 covering the surface of the main body 32 opposite to the side facing the burner 10, and a packing 45 sandwiched between the main body 32 and the cover plate 40.

[0023] The main body 32 is die-cast using a metal material such as an aluminum alloy, and is provided with multiple sets (19 sets in this embodiment) of upper and lower pairs of nozzles 31 protruding from the surface facing the burner 10 (the surface at the back in the drawing). As described above, these multiple sets of nozzles 31 are divided into four nozzle groups 31a, 31b, 31c, and 31d. Correspondingly, four recesses defined by protruding ribs 33 are formed on the surface of the main body 32 opposite the side from which the nozzles 31 protrude (the surface facing the cover plate 40), and the inner surfaces of the nozzles 31 communicate with the bottom surfaces of the recesses. That is, it has a first recess 34a connected to five sets of nozzles 31 included in the first nozzle group 31a, a second recess 34b connected to three sets of nozzles 31 included in the second nozzle group 31b, a third recess 34c connected to seven sets of nozzles 31 included in the third nozzle group 31c, and a fourth recess 34d connected to four sets of nozzles 31 included in the fourth nozzle group 31d.

[0024] Further, below the four recesses 34a, 34b, 34c, and 34d in the main body 32, a supply passage groove 35 into which the fuel gas supplied through the gas passage 15 flows is formed. The supply passage groove 35 and the first recess 34a communicate with each other via a first inlet 36a, the supply passage groove 35 and the second recess 34b communicate with each other via a second inlet 36b, the supply passage groove 35 and the third recess 34c communicate with each other via a third inlet 36c, and the supply passage groove 35 and the fourth recess 34d communicate with each other via a fourth inlet 36d.

[0025] The cover plate 40 is formed by sheet metal processing using a flat metal plate such as stainless steel, and is provided with a downward protrusion 41 that protrudes on the opposite side from the main body 32 at a portion facing the supply passage groove 35 of the main body 32. Similarly, the cover plate 40 is provided with a first protrusion 42a facing the first recess 34a, a second protrusion 42b facing the second recess 34b, a third protrusion 42c facing the third recess 34c, and a fourth protrusion 42d facing the fourth recess 34d, which protrude on the opposite side from the main body 32.

[0026] Packing 45 is formed in a sheet shape using an elastic material such as rubber, and portions thereof that face supply passage groove 35 and four recesses 34a, 34b, 34c, and 34d of main body 32 are cut out, forming a shape that surrounds supply passage groove 35 and four recesses 34a, 34b, 34c, and 34d. When assembling gas manifold 30, multiple screws 46 are used to fasten cover plate 40 so that packing 45 is pressed against main body 32.

[0027] 4 is a cross-sectional view of the gas manifold 30 taken along a plane parallel to the burner 10. FIG. 4 illustrates an example in which the gas manifold 30 is taken along the line parallel to the burner 10, where the gas manifold 30 is cut at the position of the nozzle 31 included in the third nozzle group 31c. As shown in the figure, between the main body 32 of the gas manifold 30 and the cover plate 40, a supply passage 50 is formed by the supply passage groove 35 and the downward protrusion 41, and a third distribution passage 51c is formed by the third recess 34c and the third protrusion 42c. Although not shown in detail, a first distribution passage 51a is formed by the first recess 34a and the cover plate 40 (first protrusion 42a), a second distribution passage 51b is formed by the second recess 34b and the cover plate 40 (second protrusion 42b), and a fourth distribution passage 51d is formed by the fourth recess 34d and the cover plate 40 (fourth protrusion 42d) (see FIG. 1).

[0028] The supply passage 50 is connected to the gas passage 15, and when the main valve 16 is opened, fuel gas flows into the supply passage 50. The third distribution passage 51c is connected to the supply passage 50 via a third inlet 36c, and the third switching valve 18c opens and closes the third inlet 36c. Therefore, by controlling the opening and closing of the third switching valve 18c, it is possible to switch between supplying and cutting off fuel gas to the third distribution passage 51c.

[0029] Each nozzle 31 of the third nozzle group 31c is connected to a third distribution passage 51c, and when the third switching valve 18c is opened, the fuel gas flowing in from the third inlet 36c is guided through the third distribution passage 51c to each nozzle 31 of the third nozzle group 31c. When the fuel gas is ejected from the nozzle 31, it draws in surrounding air due to the ejector effect and flows into the gas inlet 11 of the burner 10, and the mixed gas of fuel gas and air passes through the mixing passage 13 and is supplied to the flame port 12 at the upper end, whereby the mixed gas is combusted in the third burner group 10c.

[0030] Similarly, first switching valve 18a opens and closes first inlet 36a corresponding to first distribution passage 51a, second switching valve 18b opens and closes second inlet 36b corresponding to second distribution passage 51b, and fourth switching valve 18d opens and closes fourth inlet 36d corresponding to fourth distribution passage 51d. Therefore, in the combustion device 2 of this embodiment, the opening and closing of four switching valves 18a, 18b, 18c, and 18d is controlled, and depending on which of the four distribution passages 51a, 51b, 51c, and 51d fuel gas is supplied to, switching among four burner groups 10a, 10b, 10c, and 10d to perform combustion, it is possible to change the amount of heat generated (hot water supply capacity). Note that switching valves 18a, 18b, 18c, and 18d of this embodiment correspond to the "on-off valves" of the present invention.

[0031] In the combustion device 2 described above, all of the multiple burners 10 have the same specifications, and in order to manage the amount of heat generated (hot water supply capacity) in the combustion device 2 by the number of burners 10 to be combusted (selection of the burner group to be combusted from among the burner groups 10a, 10b, 10c, and 10d), it is necessary to uniformize the combustion amount in each burner 10 during combustion. In other words, it is necessary to uniform the flow rate of fuel gas ejected from each of the multiple nozzles 31 of the gas manifold 30, regardless of which nozzle group 31a, 31b, 31c, or 31d the nozzle belongs to. In the gas manifold 30, since the number of nozzles 31 included in the nozzle groups 31a, 31b, 31c, 31d corresponding to each distribution passage 51a, 51b, 51c, 51d varies, by varying the opening area (diameter) of the inlets 36a, 36b, 36c, 36d according to the number of nozzles 31, it is possible to change the resistance to the passage of the fuel gas and adjust the flow rate of the fuel gas distributed to each distribution passage 51a, 51b, 51c, 51d (each nozzle group 31a, 31b, 31c, 31d), and as a result, it is possible to uniform the flow rate of the combustion gas ejected from each nozzle 31.

[0032] However, when the main body 32 is cast by a die casting method or the like, a thin film may remain at the positions of the inlets 36a, 36b, 36c, and 36d. Therefore, it is common to form the inlets 36a, 36b, 36c, and 36d by drilling after the main body 32 is cast. In this case, the drill must be changed for each of the inlets 36a, 36b, 36c, and 36d with different diameters, which complicates the manufacturing process of the gas manifold 30. Therefore, the gas manifold 30 of this embodiment employs the following configuration to simplify the manufacturing process while still being able to adjust the flow rate of fuel gas distributed to each of the nozzle groups 31a, 31b, 31c, and 31d.

[0033] 5 is a perspective view showing the configuration of the main body 32 in the gas manifold 30 of this embodiment. First, FIG. 5(a) shows the surface of the main body 32 facing the cover plate 40. As described above, the surface of the main body 32 facing the cover plate 40 is partitioned into four recesses 34 by protruding ribs 33, and each recess 34a, 34b, 34c, and 34d communicates with the supply passage groove 35 via the corresponding inlet 36a, 36b, 36c, and 36d. In the gas manifold 30 of this embodiment, although the number of nozzles 31 included in the nozzle groups 31a, 31b, 31c, and 31d corresponding to the recesses 34a, 34b, 34c, and 34d (each distribution passage 51a, 51b, 51c, and 51d) is different, the four inlet 36a, 36b, 36c, and 36d are all formed to have approximately the same opening area (diameter).

[0034] Furthermore, except for the third recess 34c corresponding to the third nozzle group 31c having the largest number of nozzles 31, the other three recesses 34a, 34b, and 34d have barrier portions erected therein that cross the fuel gas supply direction. That is, the first recess 34a has a first barrier portion 37a that crosses the fuel gas supply direction from the first inlet 36a toward the first nozzle group 31a, the second recess 34b has a second barrier portion 37b that crosses the fuel gas supply direction from the second inlet 36b toward the second nozzle group 31b, and the fourth recess 34d has a fourth barrier portion 37d that crosses the fuel gas supply direction from the fourth inlet 36d toward the fourth nozzle group 31d.

[0035] FIG. 5(b) shows an enlarged example of a fourth barrier portion 37d provided in the fourth recess 34d. FIG. 5(b) illustrates the fourth barrier portion 37d as viewed from the fourth inlet 36d side. As shown, the fourth barrier portion 37d extends from the bottom surface of the fourth recess 34d and protrudes toward the cover plate 40 (upward in the figure) beyond the rib 33. The fourth barrier portion 37d has a generally rectangular fourth notch 38d, recessed from the cover plate 40 side, located approximately in the center. The first barrier portion 37a provided in the first recess 34a and the second barrier portion 37b provided in the second recess 34b are also basically formed in the same manner as the fourth barrier portion 37d.

[0036] FIG. 6 is a cross-sectional view of the fourth distribution passage 51d in the gas manifold 30 of this embodiment, taken along a plane perpendicular to the fuel gas supply direction. First, FIG. 6(a) shows a cross-section of the fourth distribution passage 51d taken along a position where the fourth barrier portion 37d is not provided. As described above, the ribs 33 protrude from the main body 32 side of the gas manifold 30, and the fourth recess 34d is defined between the ribs 33. When the main body 32 and the cover plate 40 are fastened with screws 46, the fourth recess 34d and the cover plate 40 form the fourth distribution passage 51d. The presence of the packing 45 between the ribs 33 and the cover plate 40 ensures airtightness of the fourth distribution passage 51d. The ribs 33 in this embodiment correspond to the "passage wall portion" of the present invention. Similarly, the first recess 34a and the cover plate 40 form a first distribution passage 51a, and the second recess 34b and the cover plate 40 form a second distribution passage 51b.

[0037] 6(b) shows a cross section of the fourth distribution passage 51d taken at the position of the fourth barrier portion 37d. In this embodiment, the fourth barrier portion 37d is erected between the ribs 33 so as to cross the fuel gas supply direction (front-to-back direction in the figure), and a fourth notch 38d is formed in the center portion from the cover plate 40 side. The fourth barrier portion 37d protrudes toward the cover plate 40 beyond the ribs 33, so that it directly contacts the cover plate 40 without the intermediary of the packing 45. The fourth notch 38d and the cover plate 40 form a fourth narrowed portion 52d that narrows the passage area of ​​the fourth distribution passage 51d. Although both end portions of the fourth barrier portion 37d near the ribs 33 do not contact the cover plate 40, the width of the packing 45 is wider than the width of the ribs 33, so that the packing 45 fills the gaps at both ends of the fourth barrier portion 37d.

[0038] By providing the fourth narrowed portion 52d in the fourth distribution passage 51d in this manner, the flow rate of fuel gas in the fourth distribution passage 51d can be regulated. Similarly, in the first distribution passage 51a, the flow rate of fuel gas can be regulated by the first narrowed portion 52a formed by the first notch 38a of the first barrier portion 37a and the cover plate 40, and in the second distribution passage 51b, the flow rate of fuel gas can be regulated by the second narrowed portion 52b formed by the second notch 38b of the second barrier portion 37b and the cover plate 40. Furthermore, since the first distribution passage 51a, the second distribution passage 51b, and the fourth distribution passage 51d each include a different number of nozzles 31 in the corresponding nozzle groups 31a, 31b, and 31d, it is possible to change the opening area of ​​the narrowed sections 52a, 52b, and 52d (at least one of the width and depth of the notches 38a, 38b, and 38d) according to the number of nozzles 31, thereby changing the resistance to the passage of the fuel gas and adjusting the flow rate of the fuel gas distributed to each of the nozzle groups 31a, 31b, and 31d.

[0039] In the gas manifold 30 of this embodiment, a barrier portion is not provided in the third recess 34c corresponding to the third nozzle group 31c, which has the largest number of nozzles 31. Therefore, the third distribution passage 51c does not have a narrowed portion. This is because the opening area (diameter) of the third inlet 36c is set according to the flow rate of fuel gas supplied to the third nozzle group 31c through the third distribution passage 51c. The first inlet 36a, the second inlet 36b, and the fourth inlet 36d are also formed to have approximately the same opening area as the third inlet 36c. However, if the opening area common to the four inlets 36a, 36b, 36c, and 36d is to be further increased, a third barrier portion 37c may also be provided in the third recess 34c, thereby forming a third narrowed portion 52c in the third distribution passage 51c.

[0040] As described above, in the gas manifold 30 of this embodiment, the four inlets 36a, 36b, 36c, and 36d are all formed with approximately the same opening area (diameter) regardless of the number of nozzles 31 included in the nozzle groups 31a, 31b, 31c, and 31d corresponding to the four distribution passages 51a, 51b, 51c, and 51d. Instead, the distribution passages 51a, 51b, and 51d have narrowed portions 52a, 52b, and 52d that regulate the flow rate of fuel gas according to the number of nozzles 31 included in the corresponding nozzle groups 31a, 31b, and 31d. These narrowed portions 52a, 52b, and 52d are formed by the cover plate 40 and notches 38a, 38b, and 38d of the barrier portions 37a, 37b, and 37c that are integrally formed on the main body 32.

[0041] In the manufacturing process of the gas manifold 30 of this embodiment, the opening areas (diameters) of the four inlets 36a, 36b, 36c, and 36d are substantially the same, so there is no need to change drills when drilling these inlets. Furthermore, the barrier portions 37a, 37b, and 37d (notches 38a, 38b, and 38d) that form the narrowed portions 52a, 52b, and 52d of the distribution passages 51a, 51b, and 51d can be integrally formed with the main body 32 by casting in accordance with the number of nozzles 31 included in the corresponding nozzle groups 31a, 31b, and 31d. Therefore, the manufacturing process of the gas manifold 30 can be simplified while adjusting the flow rate of the fuel gas distributed to each of the nozzle groups 31a, 31b, 31c, and 31d.

[0042] Furthermore, in the gas manifold 30 of this embodiment, ribs 33 that define four recesses 34a, 34b, 34c, and 34d are protrudingly provided on the surface of the main body 32 that faces the cover plate 40, and packing 45 is interposed between the cover plate 40 and the ribs 33, thereby ensuring airtightness of each distribution passage 51a, 51b, 51c, and 51d. In contrast, barrier portions 37a, 37b, and 37d provided in the recesses 34a, 34b, and 34d of the main body 32 are in direct contact with the cover plate 40 without the packing 45 interposed therebetween. In this way, the opening area of ​​the narrowed portions 52a, 52b, 52d formed by the notches 38a, 38b, 38d of the barrier portions 37a, 37b, 37d and the cover plate 40 does not depend on the compression amount of the packing 45, so that the dimensional accuracy of the opening area of ​​the narrowed portions 52a, 52b, 52d can be improved, making it possible to supply an appropriate flow rate of fuel gas to each nozzle group 31a, 31b, 31d.

[0043] In particular, in the gas manifold 30 of this embodiment, the barrier portions 37a, 37b, and 37d extending from the bottom surfaces of the recesses 34a, 34b, and 34d in the main body 32 protrude toward the cover plate 40 beyond the rib 33. Therefore, even if the packing 45 is interposed between the rib 33 and the cover plate 40, the barrier portions 37a, 37b, and 37d in the narrowed portions 52a, 52b, and 52d can be brought into direct contact with the cover plate 40. This ensures airtightness of the distribution passages 51a, 51b, 51c, and 51d while improving the dimensional accuracy of the opening areas of the narrowed portions 52a, 52b, and 52d. Furthermore, the compression amount of the packing 45 sandwiched between the rib 33 and the cover plate 40 can be adjusted (kept constant) by adjusting the protrusion amount of the barrier portions 37a, 37b, and 37d.

[0044] The gas manifold 30 of this embodiment has been described above, but the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention.

[0045] For example, in the embodiment described above, barrier portions 37a, 37b, 37d are erected between ribs 33, and notches 38a, 38b, 38d are cut out in the center from the cover plate 40 side, so that when barrier portions 37a, 37b, 37d directly contact cover plate 40, narrowed portions 52a, 52b, 52d are formed by notches 38a, 38b, 38d and cover plate 40 (see FIG. 6(b)). However, as shown in FIG. 7, barrier portions 37a, 37b, 37d may be erected from the bottom surfaces of recesses 34a, 34b, 34d separately from ribs 33, and may be located approximately midway between ribs 33. In this case, even if notches 38a, 38b, 38d are not provided in the barrier portions 37a, 37b, 37d, the barrier portions 37a, 37b, 37d are in direct contact with the cover plate 40, so that a pair of narrowed portions 52a, 52b, 52d sandwiched between the barrier portions 37a, 37b, 37d and the rib 33 is formed between the bottom surfaces of the recesses 34a, 34b, 34d and the cover plate 40. The opening area of ​​the narrowed portions 52a, 52b, 52d can be changed by changing at least one of the width and height of the barrier portions 37a, 37b, 37d, and therefore the flow rate of the fuel gas can be adjusted according to the number of nozzles 31 included in the corresponding nozzle groups 31a, 31b, 31d.

[0046] In the above-described embodiment, the barrier portions 37a, 37b, 37d that form the narrowed portions 52a, 52b, 52d are provided on the main body 32 side. However, the barrier portions 37a, 37b, 37d are not limited to being provided on the main body 32 side. When the cover plate 40 is cast by die casting or the like, the barrier portions 37a, 37b, 37d may be provided on the cover plate 40 side. Furthermore, the barrier portions 37a, 37b, 37d may be provided on both the main body 32 side and the cover plate 40 side, so that the narrowed portions 52a, 52b, 52d are formed by direct contact between the barrier portions 37a, 37b, 37d on the main body 32 side and the barrier portions 37a, 37b, 37d on the cover plate 40 side. In this case, notches 38a, 38b, 38d may be provided in at least one of the barrier portions 37a, 37b, 37d on the main body 32 side and the barrier portions 37a, 37b, 37d on the cover plate 40 side.

[0047] In the above-described embodiment, the barrier portions 37a, 37b, and 37d on the main body 32 are in direct contact with the cover plate 40 without the use of the packing 45. However, the packing 45 may be interposed between the barrier portions 37a, 37b, and 37d and the cover plate 40. In this case, a portion where the main body 32 and the cover plate 40 are in direct contact with each other (for example, a protrusion provided on the main body 32 that contacts the cover plate 40) may be separately provided so that the amount of compression of the packing 45 is constant. However, if the barrier portions 37a, 37b, and 37d are in direct contact with the cover plate 40 as in the above-described embodiment, there is no need to separately provide a protrusion, and the dimensional accuracy of the opening area of ​​the narrowed portions 52a, 52b, and 52d can be improved regardless of the amount of compression of the packing 45.

[0048] In the above-described embodiment, the nozzles 31 constituting each of the nozzle groups 31a, 31b, 31c, and 31d are provided in pairs, one above the other. However, the nozzles 31 do not have to be in pairs, and fuel gas may be ejected from a single nozzle 31 toward the corresponding burner 10. That is, the same number of single nozzles 31 as the number of burners 10 (19) may be provided, with five nozzles 31 constituting the first nozzle group 31a, three nozzles 31 constituting the second nozzle group 31b, seven nozzles 31 constituting the third nozzle group 31c, and four nozzles 31 constituting the fourth nozzle group 31d. [Explanation of symbols]

[0049] 1...water heater, 2...combustion device, 3...combustion chamber, 5...Combustion fan, 6...Spark plug, 7...Flame rod, 10... burner, 10a... first burner group, 10b... second burner group, 10c...third burner group, 10d...fourth burner group, 11...gas inlet, 12...flame nozzle; 13...mixing passage; 15...gas passage; 16...Main valve, 17...Proportional valve, 18a...First switching valve, 18b...second switching valve, 18c...third switching valve, 18d...fourth switching valve, 20... heat exchanger, 21... water supply passage, 22... hot water supply passage, 23...flow rate sensor, 24...faucet, 25...exhaust port, 30...gas manifold, 31...nozzle, 31a...first nozzle group, 31b...second nozzle group, 31c...third nozzle group, 31d...fourth nozzle group, 32...main body, 33...rib, 34a...first recess, 34b...second recess, 34c...third recess, 34d...fourth recess, 35...supply passage groove, 36a...first introduction port, 36b...second introduction port, 36c...third inlet, 36d...fourth inlet, 37a...first barrier portion, 37b...second barrier portion, 37d...fourth barrier portion, 38a...first notch, 38b...Second notch, 38d...Fourth notch, 40...Lid plate, 41...Downward raised part, 42a...First raised part, 42b...Second raised part, 42c...third raised portion, 42d...fourth raised portion, 45...packing, 46...Screw, 50...Supply passage, 51a...First distribution passage, 51b...Second distribution passage, 51c...Third distribution passage, 51d...Fourth distribution passage, 52a...first constriction section, 52b...second constriction section, 52d...fourth constriction section.

Claims

1. A gas manifold having a plurality of nozzles for ejecting fuel gas toward a plurality of burners of a combustion device, the plurality of nozzles being divided into a plurality of nozzle groups, the gas manifold distributing the fuel gas to each of the plurality of nozzle groups, a main body formed by casting and having the plurality of nozzles protruding from a surface facing the plurality of burners; a cover plate that covers a surface of the main body opposite to a side from which the nozzle protrudes and is fastened to the main body; a plurality of distribution passages formed between the main body and the cover plate, the distribution passages branching from a supply passage through which the fuel gas is supplied and directing the fuel gas to each of the plurality of nozzle groups; a plurality of inlets formed in the main body corresponding to the plurality of distribution passages, the inlets introducing the fuel gas from the supply passage into the plurality of distribution passages; a plurality of on-off valves that open and close each of the plurality of inlets; Equipped with regardless of the number of nozzles included in the nozzle group corresponding to each of the plurality of distribution passages, the plurality of introduction ports are all formed to have substantially the same opening area, At least one of the plurality of distribution passages has a narrowed portion that regulates the flow rate of the fuel gas in accordance with the number of nozzles included in the corresponding nozzle group, The narrowed portion is formed by a barrier portion integrally provided on at least one of the main body and the cover plate. A gas manifold characterized by:

2. 2. The gas manifold of claim 1, a passage wall portion that forms the plurality of distribution passages is protruded from a surface of the main body that faces the cover plate, An elastic packing is interposed between the passage wall portion of the main body and the cover plate, At the location of the distribution passage where the barrier portion is provided, the main body side and the cover plate side are in direct contact with each other without the intermediation of the packing. A gas manifold characterized by:

3. 3. The gas manifold of claim 2, the barrier portion is provided upright on a surface of the main body facing the cover plate, The barrier portion is provided so as to protrude toward the cover plate side beyond the passage wall portion. A gas manifold characterized by:

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